/usr/src/gnu/usr.bin/clang/libclangSema/../../../llvm/clang/lib/Sema/SemaOverload.cpp

Bug Summary

File:	src/gnu/usr.bin/clang/libclangSema/../../../llvm/clang/lib/Sema/SemaOverload.cpp
Warning:	line 9808, column 44 Called C++ object pointer is null
Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name SemaOverload.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangSema/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libclangSema/obj/../include/clang/Sema -I /usr/src/gnu/usr.bin/clang/libclangSema/../../../llvm/clang/include -I /usr/src/gnu/usr.bin/clang/libclangSema/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libclangSema/../include -I /usr/src/gnu/usr.bin/clang/libclangSema/obj -I /usr/src/gnu/usr.bin/clang/libclangSema/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangSema/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libclangSema/../../../llvm/clang/lib/Sema/SemaOverload.cpp
1//===--- SemaOverload.cpp - C++ Overloading -------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides Sema routines for C++ overloading.
10//
11//===----------------------------------------------------------------------===//

13#include "clang/AST/ASTContext.h"
14#include "clang/AST/CXXInheritance.h"
15#include "clang/AST/DeclObjC.h"
16#include "clang/AST/DependenceFlags.h"
17#include "clang/AST/Expr.h"
18#include "clang/AST/ExprCXX.h"
19#include "clang/AST/ExprObjC.h"
20#include "clang/AST/TypeOrdering.h"
21#include "clang/Basic/Diagnostic.h"
22#include "clang/Basic/DiagnosticOptions.h"
23#include "clang/Basic/PartialDiagnostic.h"
24#include "clang/Basic/SourceManager.h"
25#include "clang/Basic/TargetInfo.h"
26#include "clang/Sema/Initialization.h"
27#include "clang/Sema/Lookup.h"
28#include "clang/Sema/Overload.h"
29#include "clang/Sema/SemaInternal.h"
30#include "clang/Sema/Template.h"
31#include "clang/Sema/TemplateDeduction.h"
32#include "llvm/ADT/DenseSet.h"
33#include "llvm/ADT/Optional.h"
34#include "llvm/ADT/STLExtras.h"
35#include "llvm/ADT/SmallPtrSet.h"
36#include "llvm/ADT/SmallString.h"
37#include <algorithm>
38#include <cstdlib>

40using namespace clang;
41using namespace sema;

43using AllowedExplicit = Sema::AllowedExplicit;

45static bool functionHasPassObjectSizeParams(const FunctionDecl *FD) {
return llvm::any_of(FD->parameters(), [](const ParmVarDecl *P) {
  return P->hasAttr<PassObjectSizeAttr>();
});
49}

51/// A convenience routine for creating a decayed reference to a function.
52static ExprResult
53CreateFunctionRefExpr(Sema &S, FunctionDecl *Fn, NamedDecl *FoundDecl,
                    const Expr *Base, bool HadMultipleCandidates,
                    SourceLocation Loc = SourceLocation(),
                    const DeclarationNameLoc &LocInfo = DeclarationNameLoc()){
if (S.DiagnoseUseOfDecl(FoundDecl, Loc))
  return ExprError();
// If FoundDecl is different from Fn (such as if one is a template
// and the other a specialization), make sure DiagnoseUseOfDecl is
// called on both.
// FIXME: This would be more comprehensively addressed by modifying
// DiagnoseUseOfDecl to accept both the FoundDecl and the decl
// being used.
if (FoundDecl != Fn && S.DiagnoseUseOfDecl(Fn, Loc))
  return ExprError();
DeclRefExpr *DRE = new (S.Context)
    DeclRefExpr(S.Context, Fn, false, Fn->getType(), VK_LValue, Loc, LocInfo);
if (HadMultipleCandidates)
  DRE->setHadMultipleCandidates(true);

S.MarkDeclRefReferenced(DRE, Base);
if (auto *FPT = DRE->getType()->getAs<FunctionProtoType>()) {
  if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
    S.ResolveExceptionSpec(Loc, FPT);
    DRE->setType(Fn->getType());
  }
}
return S.ImpCastExprToType(DRE, S.Context.getPointerType(DRE->getType()),
                           CK_FunctionToPointerDecay);
81}

83static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
                               bool InOverloadResolution,
                               StandardConversionSequence &SCS,
                               bool CStyle,
                               bool AllowObjCWritebackConversion);

89static bool IsTransparentUnionStandardConversion(Sema &S, Expr* From,
                                               QualType &ToType,
                                               bool InOverloadResolution,
                                               StandardConversionSequence &SCS,
                                               bool CStyle);
94static OverloadingResult
95IsUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
                      UserDefinedConversionSequence& User,
                      OverloadCandidateSet& Conversions,
                      AllowedExplicit AllowExplicit,
                      bool AllowObjCConversionOnExplicit);

101static ImplicitConversionSequence::CompareKind
102CompareStandardConversionSequences(Sema &S, SourceLocation Loc,
                                 const StandardConversionSequence& SCS1,
                                 const StandardConversionSequence& SCS2);

106static ImplicitConversionSequence::CompareKind
107CompareQualificationConversions(Sema &S,
                              const StandardConversionSequence& SCS1,
                              const StandardConversionSequence& SCS2);

111static ImplicitConversionSequence::CompareKind
112CompareDerivedToBaseConversions(Sema &S, SourceLocation Loc,
                              const StandardConversionSequence& SCS1,
                              const StandardConversionSequence& SCS2);

116/// GetConversionRank - Retrieve the implicit conversion rank
117/// corresponding to the given implicit conversion kind.
118ImplicitConversionRank clang::GetConversionRank(ImplicitConversionKind Kind) {
static const ImplicitConversionRank
  Rank[(int)ICK_Num_Conversion_Kinds] = {
  ICR_Exact_Match,
  ICR_Exact_Match,
  ICR_Exact_Match,
  ICR_Exact_Match,
  ICR_Exact_Match,
  ICR_Exact_Match,
  ICR_Promotion,
  ICR_Promotion,
  ICR_Promotion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_OCL_Scalar_Widening,
  ICR_Complex_Real_Conversion,
  ICR_Conversion,
  ICR_Conversion,
  ICR_Writeback_Conversion,
  ICR_Exact_Match, // NOTE(gbiv): This may not be completely right --
                   // it was omitted by the patch that added
                   // ICK_Zero_Event_Conversion
  ICR_C_Conversion,
  ICR_C_Conversion_Extension
};
return Rank[(int)Kind];
153}

155/// GetImplicitConversionName - Return the name of this kind of
156/// implicit conversion.
157static const char* GetImplicitConversionName(ImplicitConversionKind Kind) {
static const char* const Name[(int)ICK_Num_Conversion_Kinds] = {
  "No conversion",
  "Lvalue-to-rvalue",
  "Array-to-pointer",
  "Function-to-pointer",
  "Function pointer conversion",
  "Qualification",
  "Integral promotion",
  "Floating point promotion",
  "Complex promotion",
  "Integral conversion",
  "Floating conversion",
  "Complex conversion",
  "Floating-integral conversion",
  "Pointer conversion",
  "Pointer-to-member conversion",
  "Boolean conversion",
  "Compatible-types conversion",
  "Derived-to-base conversion",
  "Vector conversion",
  "SVE Vector conversion",
  "Vector splat",
  "Complex-real conversion",
  "Block Pointer conversion",
  "Transparent Union Conversion",
  "Writeback conversion",
  "OpenCL Zero Event Conversion",
  "C specific type conversion",
  "Incompatible pointer conversion"
};
return Name[Kind];
189}

191/// StandardConversionSequence - Set the standard conversion
192/// sequence to the identity conversion.
193void StandardConversionSequence::setAsIdentityConversion() {
First = ICK_Identity;
Second = ICK_Identity;
Third = ICK_Identity;
DeprecatedStringLiteralToCharPtr = false;
QualificationIncludesObjCLifetime = false;
ReferenceBinding = false;
DirectBinding = false;
IsLvalueReference = true;
BindsToFunctionLvalue = false;
BindsToRvalue = false;
BindsImplicitObjectArgumentWithoutRefQualifier = false;
ObjCLifetimeConversionBinding = false;
CopyConstructor = nullptr;
207}

209/// getRank - Retrieve the rank of this standard conversion sequence
210/// (C++ 13.3.3.1.1p3). The rank is the largest rank of each of the
211/// implicit conversions.
212ImplicitConversionRank StandardConversionSequence::getRank() const {
ImplicitConversionRank Rank = ICR_Exact_Match;
if  (GetConversionRank(First) > Rank)
  Rank = GetConversionRank(First);
if  (GetConversionRank(Second) > Rank)
  Rank = GetConversionRank(Second);
if  (GetConversionRank(Third) > Rank)
  Rank = GetConversionRank(Third);
return Rank;
221}

223/// isPointerConversionToBool - Determines whether this conversion is
224/// a conversion of a pointer or pointer-to-member to bool. This is
225/// used as part of the ranking of standard conversion sequences
226/// (C++ 13.3.3.2p4).
227bool StandardConversionSequence::isPointerConversionToBool() const {
// Note that FromType has not necessarily been transformed by the
// array-to-pointer or function-to-pointer implicit conversions, so
// check for their presence as well as checking whether FromType is
// a pointer.
if (getToType(1)->isBooleanType() &&
    (getFromType()->isPointerType() ||
     getFromType()->isMemberPointerType() ||
     getFromType()->isObjCObjectPointerType() ||
     getFromType()->isBlockPointerType() ||
     First == ICK_Array_To_Pointer || First == ICK_Function_To_Pointer))
  return true;

return false;
241}

243/// isPointerConversionToVoidPointer - Determines whether this
244/// conversion is a conversion of a pointer to a void pointer. This is
245/// used as part of the ranking of standard conversion sequences (C++
246/// 13.3.3.2p4).
247bool
248StandardConversionSequence::
249isPointerConversionToVoidPointer(ASTContext& Context) const {
QualType FromType = getFromType();
QualType ToType = getToType(1);

// Note that FromType has not necessarily been transformed by the
// array-to-pointer implicit conversion, so check for its presence
// and redo the conversion to get a pointer.
if (First == ICK_Array_To_Pointer)
  FromType = Context.getArrayDecayedType(FromType);

if (Second == ICK_Pointer_Conversion && FromType->isAnyPointerType())
  if (const PointerType* ToPtrType = ToType->getAs<PointerType>())
    return ToPtrType->getPointeeType()->isVoidType();

return false;
264}

266/// Skip any implicit casts which could be either part of a narrowing conversion
267/// or after one in an implicit conversion.
268static const Expr *IgnoreNarrowingConversion(ASTContext &Ctx,
                                           const Expr *Converted) {
// We can have cleanups wrapping the converted expression; these need to be
// preserved so that destructors run if necessary.
if (auto *EWC = dyn_cast<ExprWithCleanups>(Converted)) {
  Expr *Inner =
      const_cast<Expr *>(IgnoreNarrowingConversion(Ctx, EWC->getSubExpr()));
  return ExprWithCleanups::Create(Ctx, Inner, EWC->cleanupsHaveSideEffects(),
                                  EWC->getObjects());
}

while (auto *ICE = dyn_cast<ImplicitCastExpr>(Converted)) {
  switch (ICE->getCastKind()) {
  case CK_NoOp:
  case CK_IntegralCast:
  case CK_IntegralToBoolean:
  case CK_IntegralToFloating:
  case CK_BooleanToSignedIntegral:
  case CK_FloatingToIntegral:
  case CK_FloatingToBoolean:
  case CK_FloatingCast:
    Converted = ICE->getSubExpr();
    continue;

  default:
    return Converted;
  }
}

return Converted;
298}

300/// Check if this standard conversion sequence represents a narrowing
301/// conversion, according to C++11 [dcl.init.list]p7.
302///
303/// \param Ctx  The AST context.
304/// \param Converted  The result of applying this standard conversion sequence.
305/// \param ConstantValue  If this is an NK_Constant_Narrowing conversion, the
306///        value of the expression prior to the narrowing conversion.
307/// \param ConstantType  If this is an NK_Constant_Narrowing conversion, the
308///        type of the expression prior to the narrowing conversion.
309/// \param IgnoreFloatToIntegralConversion If true type-narrowing conversions
310///        from floating point types to integral types should be ignored.
311NarrowingKind StandardConversionSequence::getNarrowingKind(
  ASTContext &Ctx, const Expr *Converted, APValue &ConstantValue,
  QualType &ConstantType, bool IgnoreFloatToIntegralConversion) const {
assert(Ctx.getLangOpts().CPlusPlus && "narrowing check outside C++")((void)0);

// C++11 [dcl.init.list]p7:
//   A narrowing conversion is an implicit conversion ...
QualType FromType = getToType(0);
QualType ToType = getToType(1);

// A conversion to an enumeration type is narrowing if the conversion to
// the underlying type is narrowing. This only arises for expressions of
// the form 'Enum{init}'.
if (auto *ET = ToType->getAs<EnumType>())
  ToType = ET->getDecl()->getIntegerType();

switch (Second) {
// 'bool' is an integral type; dispatch to the right place to handle it.
case ICK_Boolean_Conversion:
  if (FromType->isRealFloatingType())
    goto FloatingIntegralConversion;
  if (FromType->isIntegralOrUnscopedEnumerationType())
    goto IntegralConversion;
  // -- from a pointer type or pointer-to-member type to bool, or
  return NK_Type_Narrowing;

// -- from a floating-point type to an integer type, or
//
// -- from an integer type or unscoped enumeration type to a floating-point
//    type, except where the source is a constant expression and the actual
//    value after conversion will fit into the target type and will produce
//    the original value when converted back to the original type, or
case ICK_Floating_Integral:
FloatingIntegralConversion:
  if (FromType->isRealFloatingType() && ToType->isIntegralType(Ctx)) {
    return NK_Type_Narrowing;
  } else if (FromType->isIntegralOrUnscopedEnumerationType() &&
             ToType->isRealFloatingType()) {
    if (IgnoreFloatToIntegralConversion)
      return NK_Not_Narrowing;
    const Expr *Initializer = IgnoreNarrowingConversion(Ctx, Converted);
    assert(Initializer && "Unknown conversion expression")((void)0);

    // If it's value-dependent, we can't tell whether it's narrowing.
    if (Initializer->isValueDependent())
      return NK_Dependent_Narrowing;

    if (Optional<llvm::APSInt> IntConstantValue =
            Initializer->getIntegerConstantExpr(Ctx)) {
      // Convert the integer to the floating type.
      llvm::APFloat Result(Ctx.getFloatTypeSemantics(ToType));
      Result.convertFromAPInt(*IntConstantValue, IntConstantValue->isSigned(),
                              llvm::APFloat::rmNearestTiesToEven);
      // And back.
      llvm::APSInt ConvertedValue = *IntConstantValue;
      bool ignored;
      Result.convertToInteger(ConvertedValue,
                              llvm::APFloat::rmTowardZero, &ignored);
      // If the resulting value is different, this was a narrowing conversion.
      if (*IntConstantValue != ConvertedValue) {
        ConstantValue = APValue(*IntConstantValue);
        ConstantType = Initializer->getType();
        return NK_Constant_Narrowing;
      }
    } else {
      // Variables are always narrowings.
      return NK_Variable_Narrowing;
    }
  }
  return NK_Not_Narrowing;

// -- from long double to double or float, or from double to float, except
//    where the source is a constant expression and the actual value after
//    conversion is within the range of values that can be represented (even
//    if it cannot be represented exactly), or
case ICK_Floating_Conversion:
  if (FromType->isRealFloatingType() && ToType->isRealFloatingType() &&
      Ctx.getFloatingTypeOrder(FromType, ToType) == 1) {
    // FromType is larger than ToType.
    const Expr *Initializer = IgnoreNarrowingConversion(Ctx, Converted);

    // If it's value-dependent, we can't tell whether it's narrowing.
    if (Initializer->isValueDependent())
      return NK_Dependent_Narrowing;

    if (Initializer->isCXX11ConstantExpr(Ctx, &ConstantValue)) {
      // Constant!
      assert(ConstantValue.isFloat())((void)0);
      llvm::APFloat FloatVal = ConstantValue.getFloat();
      // Convert the source value into the target type.
      bool ignored;
      llvm::APFloat::opStatus ConvertStatus = FloatVal.convert(
        Ctx.getFloatTypeSemantics(ToType),
        llvm::APFloat::rmNearestTiesToEven, &ignored);
      // If there was no overflow, the source value is within the range of
      // values that can be represented.
      if (ConvertStatus & llvm::APFloat::opOverflow) {
        ConstantType = Initializer->getType();
        return NK_Constant_Narrowing;
      }
    } else {
      return NK_Variable_Narrowing;
    }
  }
  return NK_Not_Narrowing;

// -- from an integer type or unscoped enumeration type to an integer type
//    that cannot represent all the values of the original type, except where
//    the source is a constant expression and the actual value after
//    conversion will fit into the target type and will produce the original
//    value when converted back to the original type.
case ICK_Integral_Conversion:
IntegralConversion: {
  assert(FromType->isIntegralOrUnscopedEnumerationType())((void)0);
  assert(ToType->isIntegralOrUnscopedEnumerationType())((void)0);
  const bool FromSigned = FromType->isSignedIntegerOrEnumerationType();
  const unsigned FromWidth = Ctx.getIntWidth(FromType);
  const bool ToSigned = ToType->isSignedIntegerOrEnumerationType();
  const unsigned ToWidth = Ctx.getIntWidth(ToType);

  if (FromWidth > ToWidth ||
      (FromWidth == ToWidth && FromSigned != ToSigned) ||
      (FromSigned && !ToSigned)) {
    // Not all values of FromType can be represented in ToType.
    const Expr *Initializer = IgnoreNarrowingConversion(Ctx, Converted);

    // If it's value-dependent, we can't tell whether it's narrowing.
    if (Initializer->isValueDependent())
      return NK_Dependent_Narrowing;

    Optional<llvm::APSInt> OptInitializerValue;
    if (!(OptInitializerValue = Initializer->getIntegerConstantExpr(Ctx))) {
      // Such conversions on variables are always narrowing.
      return NK_Variable_Narrowing;
    }
    llvm::APSInt &InitializerValue = *OptInitializerValue;
    bool Narrowing = false;
    if (FromWidth < ToWidth) {
      // Negative -> unsigned is narrowing. Otherwise, more bits is never
      // narrowing.
      if (InitializerValue.isSigned() && InitializerValue.isNegative())
        Narrowing = true;
    } else {
      // Add a bit to the InitializerValue so we don't have to worry about
      // signed vs. unsigned comparisons.
      InitializerValue = InitializerValue.extend(
        InitializerValue.getBitWidth() + 1);
      // Convert the initializer to and from the target width and signed-ness.
      llvm::APSInt ConvertedValue = InitializerValue;
      ConvertedValue = ConvertedValue.trunc(ToWidth);
      ConvertedValue.setIsSigned(ToSigned);
      ConvertedValue = ConvertedValue.extend(InitializerValue.getBitWidth());
      ConvertedValue.setIsSigned(InitializerValue.isSigned());
      // If the result is different, this was a narrowing conversion.
      if (ConvertedValue != InitializerValue)
        Narrowing = true;
    }
    if (Narrowing) {
      ConstantType = Initializer->getType();
      ConstantValue = APValue(InitializerValue);
      return NK_Constant_Narrowing;
    }
  }
  return NK_Not_Narrowing;
}

default:
  // Other kinds of conversions are not narrowings.
  return NK_Not_Narrowing;
}
481}

483/// dump - Print this standard conversion sequence to standard
484/// error. Useful for debugging overloading issues.
485LLVM_DUMP_METHOD__attribute__((noinline)) void StandardConversionSequence::dump() const {
raw_ostream &OS = llvm::errs();
bool PrintedSomething = false;
if (First != ICK_Identity) {
  OS << GetImplicitConversionName(First);
  PrintedSomething = true;
}

if (Second != ICK_Identity) {
  if (PrintedSomething) {
    OS << " -> ";
  }
  OS << GetImplicitConversionName(Second);

  if (CopyConstructor) {
    OS << " (by copy constructor)";
  } else if (DirectBinding) {
    OS << " (direct reference binding)";
  } else if (ReferenceBinding) {
    OS << " (reference binding)";
  }
  PrintedSomething = true;
}

if (Third != ICK_Identity) {
  if (PrintedSomething) {
    OS << " -> ";
  }
  OS << GetImplicitConversionName(Third);
  PrintedSomething = true;
}

if (!PrintedSomething) {
  OS << "No conversions required";
}
520}

522/// dump - Print this user-defined conversion sequence to standard
523/// error. Useful for debugging overloading issues.
524void UserDefinedConversionSequence::dump() const {
raw_ostream &OS = llvm::errs();
if (Before.First || Before.Second || Before.Third) {
  Before.dump();
  OS << " -> ";
}
if (ConversionFunction)
  OS << '\'' << *ConversionFunction << '\'';
else
  OS << "aggregate initialization";
if (After.First || After.Second || After.Third) {
  OS << " -> ";
  After.dump();
}
538}

540/// dump - Print this implicit conversion sequence to standard
541/// error. Useful for debugging overloading issues.
542void ImplicitConversionSequence::dump() const {
raw_ostream &OS = llvm::errs();
if (isStdInitializerListElement())
  OS << "Worst std::initializer_list element conversion: ";
switch (ConversionKind) {
case StandardConversion:
  OS << "Standard conversion: ";
  Standard.dump();
  break;
case UserDefinedConversion:
  OS << "User-defined conversion: ";
  UserDefined.dump();
  break;
case EllipsisConversion:
  OS << "Ellipsis conversion";
  break;
case AmbiguousConversion:
  OS << "Ambiguous conversion";
  break;
case BadConversion:
  OS << "Bad conversion";
  break;
}

OS << "\n";
567}

569void AmbiguousConversionSequence::construct() {
new (&conversions()) ConversionSet();
571}

573void AmbiguousConversionSequence::destruct() {
conversions().~ConversionSet();
575}

577void
578AmbiguousConversionSequence::copyFrom(const AmbiguousConversionSequence &O) {
FromTypePtr = O.FromTypePtr;
ToTypePtr = O.ToTypePtr;
new (&conversions()) ConversionSet(O.conversions());
582}

584namespace {
// Structure used by DeductionFailureInfo to store
// template argument information.
struct DFIArguments {
  TemplateArgument FirstArg;
  TemplateArgument SecondArg;
};
// Structure used by DeductionFailureInfo to store
// template parameter and template argument information.
struct DFIParamWithArguments : DFIArguments {
  TemplateParameter Param;
};
// Structure used by DeductionFailureInfo to store template argument
// information and the index of the problematic call argument.
struct DFIDeducedMismatchArgs : DFIArguments {
  TemplateArgumentList *TemplateArgs;
  unsigned CallArgIndex;
};
// Structure used by DeductionFailureInfo to store information about
// unsatisfied constraints.
struct CNSInfo {
  TemplateArgumentList *TemplateArgs;
  ConstraintSatisfaction Satisfaction;
};
608}

610/// Convert from Sema's representation of template deduction information
611/// to the form used in overload-candidate information.
612DeductionFailureInfo
613clang::MakeDeductionFailureInfo(ASTContext &Context,
                              Sema::TemplateDeductionResult TDK,
                              TemplateDeductionInfo &Info) {
DeductionFailureInfo Result;
Result.Result = static_cast<unsigned>(TDK);
Result.HasDiagnostic = false;
switch (TDK) {
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_MiscellaneousDeductionFailure:
case Sema::TDK_CUDATargetMismatch:
  Result.Data = nullptr;
  break;

case Sema::TDK_Incomplete:
case Sema::TDK_InvalidExplicitArguments:
  Result.Data = Info.Param.getOpaqueValue();
  break;

case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested: {
  // FIXME: Should allocate from normal heap so that we can free this later.
  auto *Saved = new (Context) DFIDeducedMismatchArgs;
  Saved->FirstArg = Info.FirstArg;
  Saved->SecondArg = Info.SecondArg;
  Saved->TemplateArgs = Info.take();
  Saved->CallArgIndex = Info.CallArgIndex;
  Result.Data = Saved;
  break;
}

case Sema::TDK_NonDeducedMismatch: {
  // FIXME: Should allocate from normal heap so that we can free this later.
  DFIArguments *Saved = new (Context) DFIArguments;
  Saved->FirstArg = Info.FirstArg;
  Saved->SecondArg = Info.SecondArg;
  Result.Data = Saved;
  break;
}

case Sema::TDK_IncompletePack:
  // FIXME: It's slightly wasteful to allocate two TemplateArguments for this.
case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified: {
  // FIXME: Should allocate from normal heap so that we can free this later.
  DFIParamWithArguments *Saved = new (Context) DFIParamWithArguments;
  Saved->Param = Info.Param;
  Saved->FirstArg = Info.FirstArg;
  Saved->SecondArg = Info.SecondArg;
  Result.Data = Saved;
  break;
}

case Sema::TDK_SubstitutionFailure:
  Result.Data = Info.take();
  if (Info.hasSFINAEDiagnostic()) {
    PartialDiagnosticAt *Diag = new (Result.Diagnostic) PartialDiagnosticAt(
        SourceLocation(), PartialDiagnostic::NullDiagnostic());
    Info.takeSFINAEDiagnostic(*Diag);
    Result.HasDiagnostic = true;
  }
  break;

case Sema::TDK_ConstraintsNotSatisfied: {
  CNSInfo *Saved = new (Context) CNSInfo;
  Saved->TemplateArgs = Info.take();
  Saved->Satisfaction = Info.AssociatedConstraintsSatisfaction;
  Result.Data = Saved;
  break;
}

case Sema::TDK_Success:
case Sema::TDK_NonDependentConversionFailure:
  llvm_unreachable("not a deduction failure")__builtin_unreachable();
}

return Result;
692}

694void DeductionFailureInfo::Destroy() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_Success:
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_Incomplete:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_InvalidExplicitArguments:
case Sema::TDK_CUDATargetMismatch:
case Sema::TDK_NonDependentConversionFailure:
  break;

case Sema::TDK_IncompletePack:
case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified:
case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
case Sema::TDK_NonDeducedMismatch:
  // FIXME: Destroy the data?
  Data = nullptr;
  break;

case Sema::TDK_SubstitutionFailure:
  // FIXME: Destroy the template argument list?
  Data = nullptr;
  if (PartialDiagnosticAt *Diag = getSFINAEDiagnostic()) {
    Diag->~PartialDiagnosticAt();
    HasDiagnostic = false;
  }
  break;

case Sema::TDK_ConstraintsNotSatisfied:
  // FIXME: Destroy the template argument list?
  Data = nullptr;
  if (PartialDiagnosticAt *Diag = getSFINAEDiagnostic()) {
    Diag->~PartialDiagnosticAt();
    HasDiagnostic = false;
  }
  break;

// Unhandled
case Sema::TDK_MiscellaneousDeductionFailure:
  break;
}
739}

741PartialDiagnosticAt *DeductionFailureInfo::getSFINAEDiagnostic() {
if (HasDiagnostic)
  return static_cast<PartialDiagnosticAt*>(static_cast<void*>(Diagnostic));
return nullptr;
745}

747TemplateParameter DeductionFailureInfo::getTemplateParameter() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_Success:
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_SubstitutionFailure:
case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
case Sema::TDK_NonDeducedMismatch:
case Sema::TDK_CUDATargetMismatch:
case Sema::TDK_NonDependentConversionFailure:
case Sema::TDK_ConstraintsNotSatisfied:
  return TemplateParameter();

case Sema::TDK_Incomplete:
case Sema::TDK_InvalidExplicitArguments:
  return TemplateParameter::getFromOpaqueValue(Data);

case Sema::TDK_IncompletePack:
case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified:
  return static_cast<DFIParamWithArguments*>(Data)->Param;

// Unhandled
case Sema::TDK_MiscellaneousDeductionFailure:
  break;
}

return TemplateParameter();
778}

780TemplateArgumentList *DeductionFailureInfo::getTemplateArgumentList() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_Success:
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_Incomplete:
case Sema::TDK_IncompletePack:
case Sema::TDK_InvalidExplicitArguments:
case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified:
case Sema::TDK_NonDeducedMismatch:
case Sema::TDK_CUDATargetMismatch:
case Sema::TDK_NonDependentConversionFailure:
  return nullptr;

case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
  return static_cast<DFIDeducedMismatchArgs*>(Data)->TemplateArgs;

case Sema::TDK_SubstitutionFailure:
  return static_cast<TemplateArgumentList*>(Data);

case Sema::TDK_ConstraintsNotSatisfied:
  return static_cast<CNSInfo*>(Data)->TemplateArgs;

// Unhandled
case Sema::TDK_MiscellaneousDeductionFailure:
  break;
}

return nullptr;
813}

815const TemplateArgument *DeductionFailureInfo::getFirstArg() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_Success:
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_Incomplete:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_InvalidExplicitArguments:
case Sema::TDK_SubstitutionFailure:
case Sema::TDK_CUDATargetMismatch:
case Sema::TDK_NonDependentConversionFailure:
case Sema::TDK_ConstraintsNotSatisfied:
  return nullptr;

case Sema::TDK_IncompletePack:
case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified:
case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
case Sema::TDK_NonDeducedMismatch:
  return &static_cast<DFIArguments*>(Data)->FirstArg;

// Unhandled
case Sema::TDK_MiscellaneousDeductionFailure:
  break;
}

return nullptr;
844}

846const TemplateArgument *DeductionFailureInfo::getSecondArg() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_Success:
case Sema::TDK_Invalid:
case Sema::TDK_InstantiationDepth:
case Sema::TDK_Incomplete:
case Sema::TDK_IncompletePack:
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
case Sema::TDK_InvalidExplicitArguments:
case Sema::TDK_SubstitutionFailure:
case Sema::TDK_CUDATargetMismatch:
case Sema::TDK_NonDependentConversionFailure:
case Sema::TDK_ConstraintsNotSatisfied:
  return nullptr;

case Sema::TDK_Inconsistent:
case Sema::TDK_Underqualified:
case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
case Sema::TDK_NonDeducedMismatch:
  return &static_cast<DFIArguments*>(Data)->SecondArg;

// Unhandled
case Sema::TDK_MiscellaneousDeductionFailure:
  break;
}

return nullptr;
875}

877llvm::Optional<unsigned> DeductionFailureInfo::getCallArgIndex() {
switch (static_cast<Sema::TemplateDeductionResult>(Result)) {
case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested:
  return static_cast<DFIDeducedMismatchArgs*>(Data)->CallArgIndex;

default:
  return llvm::None;
}
886}

888bool OverloadCandidateSet::OperatorRewriteInfo::shouldAddReversed(
  OverloadedOperatorKind Op) {
if (!AllowRewrittenCandidates)
  return false;
return Op == OO_EqualEqual || Op == OO_Spaceship;
893}

895bool OverloadCandidateSet::OperatorRewriteInfo::shouldAddReversed(
  ASTContext &Ctx, const FunctionDecl *FD) {
if (!shouldAddReversed(FD->getDeclName().getCXXOverloadedOperator()))
  return false;
// Don't bother adding a reversed candidate that can never be a better
// match than the non-reversed version.
return FD->getNumParams() != 2 ||
       !Ctx.hasSameUnqualifiedType(FD->getParamDecl(0)->getType(),
                                   FD->getParamDecl(1)->getType()) ||
       FD->hasAttr<EnableIfAttr>();
905}

907void OverloadCandidateSet::destroyCandidates() {
for (iterator i = begin(), e = end(); i != e; ++i) {
  for (auto &C : i->Conversions)
    C.~ImplicitConversionSequence();
  if (!i->Viable && i->FailureKind == ovl_fail_bad_deduction)
    i->DeductionFailure.Destroy();
}
914}

916void OverloadCandidateSet::clear(CandidateSetKind CSK) {
destroyCandidates();
SlabAllocator.Reset();
NumInlineBytesUsed = 0;
Candidates.clear();
Functions.clear();
Kind = CSK;
923}

925namespace {
class UnbridgedCastsSet {
  struct Entry {
    Expr **Addr;
    Expr *Saved;
  };
  SmallVector<Entry, 2> Entries;

public:
  void save(Sema &S, Expr *&E) {
    assert(E->hasPlaceholderType(BuiltinType::ARCUnbridgedCast))((void)0);
    Entry entry = { &E, E };
    Entries.push_back(entry);
    E = S.stripARCUnbridgedCast(E);
  }

  void restore() {
    for (SmallVectorImpl<Entry>::iterator
           i = Entries.begin(), e = Entries.end(); i != e; ++i)
      *i->Addr = i->Saved;
  }
};
947}

949/// checkPlaceholderForOverload - Do any interesting placeholder-like
950/// preprocessing on the given expression.
951///
952/// \param unbridgedCasts a collection to which to add unbridged casts;
953///   without this, they will be immediately diagnosed as errors
954///
955/// Return true on unrecoverable error.
956static bool
957checkPlaceholderForOverload(Sema &S, Expr *&E,
                          UnbridgedCastsSet *unbridgedCasts = nullptr) {
if (const BuiltinType *placeholder =  E->getType()->getAsPlaceholderType()) {
  // We can't handle overloaded expressions here because overload
  // resolution might reasonably tweak them.
  if (placeholder->getKind() == BuiltinType::Overload) return false;

  // If the context potentially accepts unbridged ARC casts, strip
  // the unbridged cast and add it to the collection for later restoration.
  if (placeholder->getKind() == BuiltinType::ARCUnbridgedCast &&
      unbridgedCasts) {
    unbridgedCasts->save(S, E);
    return false;
  }

  // Go ahead and check everything else.
  ExprResult result = S.CheckPlaceholderExpr(E);
  if (result.isInvalid())
    return true;

  E = result.get();
  return false;
}

// Nothing to do.
return false;
983}

985/// checkArgPlaceholdersForOverload - Check a set of call operands for
986/// placeholders.
987static bool checkArgPlaceholdersForOverload(Sema &S,
                                          MultiExprArg Args,
                                          UnbridgedCastsSet &unbridged) {
for (unsigned i = 0, e = Args.size(); i != e; ++i)
  if (checkPlaceholderForOverload(S, Args[i], &unbridged))
    return true;

return false;
995}

997/// Determine whether the given New declaration is an overload of the
998/// declarations in Old. This routine returns Ovl_Match or Ovl_NonFunction if
999/// New and Old cannot be overloaded, e.g., if New has the same signature as
1000/// some function in Old (C++ 1.3.10) or if the Old declarations aren't
1001/// functions (or function templates) at all. When it does return Ovl_Match or
1002/// Ovl_NonFunction, MatchedDecl will point to the decl that New cannot be
1003/// overloaded with. This decl may be a UsingShadowDecl on top of the underlying
1004/// declaration.
1005///
1006/// Example: Given the following input:
1007///
1008///   void f(int, float); // #1
1009///   void f(int, int); // #2
1010///   int f(int, int); // #3
1011///
1012/// When we process #1, there is no previous declaration of "f", so IsOverload
1013/// will not be used.
1014///
1015/// When we process #2, Old contains only the FunctionDecl for #1. By comparing
1016/// the parameter types, we see that #1 and #2 are overloaded (since they have
1017/// different signatures), so this routine returns Ovl_Overload; MatchedDecl is
1018/// unchanged.
1019///
1020/// When we process #3, Old is an overload set containing #1 and #2. We compare
1021/// the signatures of #3 to #1 (they're overloaded, so we do nothing) and then
1022/// #3 to #2. Since the signatures of #3 and #2 are identical (return types of
1023/// functions are not part of the signature), IsOverload returns Ovl_Match and
1024/// MatchedDecl will be set to point to the FunctionDecl for #2.
1025///
1026/// 'NewIsUsingShadowDecl' indicates that 'New' is being introduced into a class
1027/// by a using declaration. The rules for whether to hide shadow declarations
1028/// ignore some properties which otherwise figure into a function template's
1029/// signature.
1030Sema::OverloadKind
1031Sema::CheckOverload(Scope *S, FunctionDecl *New, const LookupResult &Old,
                  NamedDecl *&Match, bool NewIsUsingDecl) {
for (LookupResult::iterator I = Old.begin(), E = Old.end();
       I != E; ++I) {
  NamedDecl *OldD = *I;

  bool OldIsUsingDecl = false;
  if (isa<UsingShadowDecl>(OldD)) {
    OldIsUsingDecl = true;

    // We can always introduce two using declarations into the same
    // context, even if they have identical signatures.
    if (NewIsUsingDecl) continue;

    OldD = cast<UsingShadowDecl>(OldD)->getTargetDecl();
  }

  // A using-declaration does not conflict with another declaration
  // if one of them is hidden.
  if ((OldIsUsingDecl || NewIsUsingDecl) && !isVisible(*I))
    continue;

  // If either declaration was introduced by a using declaration,
  // we'll need to use slightly different rules for matching.
  // Essentially, these rules are the normal rules, except that
  // function templates hide function templates with different
  // return types or template parameter lists.
  bool UseMemberUsingDeclRules =
    (OldIsUsingDecl || NewIsUsingDecl) && CurContext->isRecord() &&
    !New->getFriendObjectKind();

  if (FunctionDecl *OldF = OldD->getAsFunction()) {
    if (!IsOverload(New, OldF, UseMemberUsingDeclRules)) {
      if (UseMemberUsingDeclRules && OldIsUsingDecl) {
        HideUsingShadowDecl(S, cast<UsingShadowDecl>(*I));
        continue;
      }

      if (!isa<FunctionTemplateDecl>(OldD) &&
          !shouldLinkPossiblyHiddenDecl(*I, New))
        continue;

      Match = *I;
      return Ovl_Match;
    }

    // Builtins that have custom typechecking or have a reference should
    // not be overloadable or redeclarable.
    if (!getASTContext().canBuiltinBeRedeclared(OldF)) {
      Match = *I;
      return Ovl_NonFunction;
    }
  } else if (isa<UsingDecl>(OldD) || isa<UsingPackDecl>(OldD)) {
    // We can overload with these, which can show up when doing
    // redeclaration checks for UsingDecls.
    assert(Old.getLookupKind() == LookupUsingDeclName)((void)0);
  } else if (isa<TagDecl>(OldD)) {
    // We can always overload with tags by hiding them.
  } else if (auto *UUD = dyn_cast<UnresolvedUsingValueDecl>(OldD)) {
    // Optimistically assume that an unresolved using decl will
    // overload; if it doesn't, we'll have to diagnose during
    // template instantiation.
    //
    // Exception: if the scope is dependent and this is not a class
    // member, the using declaration can only introduce an enumerator.
    if (UUD->getQualifier()->isDependent() && !UUD->isCXXClassMember()) {
      Match = *I;
      return Ovl_NonFunction;
    }
  } else {
    // (C++ 13p1):
    //   Only function declarations can be overloaded; object and type
    //   declarations cannot be overloaded.
    Match = *I;
    return Ovl_NonFunction;
  }
}

// C++ [temp.friend]p1:
//   For a friend function declaration that is not a template declaration:
//    -- if the name of the friend is a qualified or unqualified template-id,
//       [...], otherwise
//    -- if the name of the friend is a qualified-id and a matching
//       non-template function is found in the specified class or namespace,
//       the friend declaration refers to that function, otherwise,
//    -- if the name of the friend is a qualified-id and a matching function
//       template is found in the specified class or namespace, the friend
//       declaration refers to the deduced specialization of that function
//       template, otherwise
//    -- the name shall be an unqualified-id [...]
// If we get here for a qualified friend declaration, we've just reached the
// third bullet. If the type of the friend is dependent, skip this lookup
// until instantiation.
if (New->getFriendObjectKind() && New->getQualifier() &&
    !New->getDescribedFunctionTemplate() &&
    !New->getDependentSpecializationInfo() &&
    !New->getType()->isDependentType()) {
  LookupResult TemplateSpecResult(LookupResult::Temporary, Old);
  TemplateSpecResult.addAllDecls(Old);
  if (CheckFunctionTemplateSpecialization(New, nullptr, TemplateSpecResult,
                                          /*QualifiedFriend*/true)) {
    New->setInvalidDecl();
    return Ovl_Overload;
  }

  Match = TemplateSpecResult.getAsSingle<FunctionDecl>();
  return Ovl_Match;
}

return Ovl_Overload;
1141}

1143bool Sema::IsOverload(FunctionDecl *New, FunctionDecl *Old,
                    bool UseMemberUsingDeclRules, bool ConsiderCudaAttrs,
                    bool ConsiderRequiresClauses) {
// C++ [basic.start.main]p2: This function shall not be overloaded.
if (New->isMain())
  return false;

// MSVCRT user defined entry points cannot be overloaded.
if (New->isMSVCRTEntryPoint())
  return false;

FunctionTemplateDecl *OldTemplate = Old->getDescribedFunctionTemplate();
FunctionTemplateDecl *NewTemplate = New->getDescribedFunctionTemplate();

// C++ [temp.fct]p2:
//   A function template can be overloaded with other function templates
//   and with normal (non-template) functions.
if ((OldTemplate == nullptr) != (NewTemplate == nullptr))
  return true;

// Is the function New an overload of the function Old?
QualType OldQType = Context.getCanonicalType(Old->getType());
QualType NewQType = Context.getCanonicalType(New->getType());

// Compare the signatures (C++ 1.3.10) of the two functions to
// determine whether they are overloads. If we find any mismatch
// in the signature, they are overloads.

// If either of these functions is a K&R-style function (no
// prototype), then we consider them to have matching signatures.
if (isa<FunctionNoProtoType>(OldQType.getTypePtr()) ||
    isa<FunctionNoProtoType>(NewQType.getTypePtr()))
  return false;

const FunctionProtoType *OldType = cast<FunctionProtoType>(OldQType);
const FunctionProtoType *NewType = cast<FunctionProtoType>(NewQType);

// The signature of a function includes the types of its
// parameters (C++ 1.3.10), which includes the presence or absence
// of the ellipsis; see C++ DR 357).
if (OldQType != NewQType &&
    (OldType->getNumParams() != NewType->getNumParams() ||
     OldType->isVariadic() != NewType->isVariadic() ||
     !FunctionParamTypesAreEqual(OldType, NewType)))
  return true;

// C++ [temp.over.link]p4:
//   The signature of a function template consists of its function
//   signature, its return type and its template parameter list. The names
//   of the template parameters are significant only for establishing the
//   relationship between the template parameters and the rest of the
//   signature.
//
// We check the return type and template parameter lists for function
// templates first; the remaining checks follow.
//
// However, we don't consider either of these when deciding whether
// a member introduced by a shadow declaration is hidden.
if (!UseMemberUsingDeclRules && NewTemplate &&
    (!TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
                                     OldTemplate->getTemplateParameters(),
                                     false, TPL_TemplateMatch) ||
     !Context.hasSameType(Old->getDeclaredReturnType(),
                          New->getDeclaredReturnType())))
  return true;

// If the function is a class member, its signature includes the
// cv-qualifiers (if any) and ref-qualifier (if any) on the function itself.
//
// As part of this, also check whether one of the member functions
// is static, in which case they are not overloads (C++
// 13.1p2). While not part of the definition of the signature,
// this check is important to determine whether these functions
// can be overloaded.
CXXMethodDecl *OldMethod = dyn_cast<CXXMethodDecl>(Old);
CXXMethodDecl *NewMethod = dyn_cast<CXXMethodDecl>(New);
if (OldMethod && NewMethod &&
    !OldMethod->isStatic() && !NewMethod->isStatic()) {
  if (OldMethod->getRefQualifier() != NewMethod->getRefQualifier()) {
    if (!UseMemberUsingDeclRules &&
        (OldMethod->getRefQualifier() == RQ_None ||
         NewMethod->getRefQualifier() == RQ_None)) {
      // C++0x [over.load]p2:
      //   - Member function declarations with the same name and the same
      //     parameter-type-list as well as member function template
      //     declarations with the same name, the same parameter-type-list, and
      //     the same template parameter lists cannot be overloaded if any of
      //     them, but not all, have a ref-qualifier (8.3.5).
      Diag(NewMethod->getLocation(), diag::err_ref_qualifier_overload)
        << NewMethod->getRefQualifier() << OldMethod->getRefQualifier();
      Diag(OldMethod->getLocation(), diag::note_previous_declaration);
    }
    return true;
  }

  // We may not have applied the implicit const for a constexpr member
  // function yet (because we haven't yet resolved whether this is a static
  // or non-static member function). Add it now, on the assumption that this
  // is a redeclaration of OldMethod.
  auto OldQuals = OldMethod->getMethodQualifiers();
  auto NewQuals = NewMethod->getMethodQualifiers();
  if (!getLangOpts().CPlusPlus14 && NewMethod->isConstexpr() &&
      !isa<CXXConstructorDecl>(NewMethod))
    NewQuals.addConst();
  // We do not allow overloading based off of '__restrict'.
  OldQuals.removeRestrict();
  NewQuals.removeRestrict();
  if (OldQuals != NewQuals)
    return true;
}

// Though pass_object_size is placed on parameters and takes an argument, we
// consider it to be a function-level modifier for the sake of function
// identity. Either the function has one or more parameters with
// pass_object_size or it doesn't.
if (functionHasPassObjectSizeParams(New) !=
    functionHasPassObjectSizeParams(Old))
  return true;

// enable_if attributes are an order-sensitive part of the signature.
for (specific_attr_iterator<EnableIfAttr>
       NewI = New->specific_attr_begin<EnableIfAttr>(),
       NewE = New->specific_attr_end<EnableIfAttr>(),
       OldI = Old->specific_attr_begin<EnableIfAttr>(),
       OldE = Old->specific_attr_end<EnableIfAttr>();
     NewI != NewE || OldI != OldE; ++NewI, ++OldI) {
  if (NewI == NewE || OldI == OldE)
    return true;
  llvm::FoldingSetNodeID NewID, OldID;
  NewI->getCond()->Profile(NewID, Context, true);
  OldI->getCond()->Profile(OldID, Context, true);
  if (NewID != OldID)
    return true;
}

if (getLangOpts().CUDA && ConsiderCudaAttrs) {
  // Don't allow overloading of destructors.  (In theory we could, but it
  // would be a giant change to clang.)
  if (!isa<CXXDestructorDecl>(New)) {
    CUDAFunctionTarget NewTarget = IdentifyCUDATarget(New),
                       OldTarget = IdentifyCUDATarget(Old);
    if (NewTarget != CFT_InvalidTarget) {
      assert((OldTarget != CFT_InvalidTarget) &&((void)0)
             "Unexpected invalid target.")((void)0);

      // Allow overloading of functions with same signature and different CUDA
      // target attributes.
      if (NewTarget != OldTarget)
        return true;
    }
  }
}

if (ConsiderRequiresClauses) {
  Expr *NewRC = New->getTrailingRequiresClause(),
       *OldRC = Old->getTrailingRequiresClause();
  if ((NewRC != nullptr) != (OldRC != nullptr))
    // RC are most certainly different - these are overloads.
    return true;

  if (NewRC) {
    llvm::FoldingSetNodeID NewID, OldID;
    NewRC->Profile(NewID, Context, /*Canonical=*/true);
    OldRC->Profile(OldID, Context, /*Canonical=*/true);
    if (NewID != OldID)
      // RCs are not equivalent - these are overloads.
      return true;
  }
}

// The signatures match; this is not an overload.
return false;
1315}

1317/// Tries a user-defined conversion from From to ToType.
1318///
1319/// Produces an implicit conversion sequence for when a standard conversion
1320/// is not an option. See TryImplicitConversion for more information.
1321static ImplicitConversionSequence
1322TryUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
                       bool SuppressUserConversions,
                       AllowedExplicit AllowExplicit,
                       bool InOverloadResolution,
                       bool CStyle,
                       bool AllowObjCWritebackConversion,
                       bool AllowObjCConversionOnExplicit) {
ImplicitConversionSequence ICS;

if (SuppressUserConversions) {
  // We're not in the case above, so there is no conversion that
  // we can perform.
  ICS.setBad(BadConversionSequence::no_conversion, From, ToType);
  return ICS;
}

// Attempt user-defined conversion.
OverloadCandidateSet Conversions(From->getExprLoc(),
                                 OverloadCandidateSet::CSK_Normal);
switch (IsUserDefinedConversion(S, From, ToType, ICS.UserDefined,
                                Conversions, AllowExplicit,
                                AllowObjCConversionOnExplicit)) {
case OR_Success:
case OR_Deleted:
  ICS.setUserDefined();
  // C++ [over.ics.user]p4:
  //   A conversion of an expression of class type to the same class
  //   type is given Exact Match rank, and a conversion of an
  //   expression of class type to a base class of that type is
  //   given Conversion rank, in spite of the fact that a copy
  //   constructor (i.e., a user-defined conversion function) is
  //   called for those cases.
  if (CXXConstructorDecl *Constructor
        = dyn_cast<CXXConstructorDecl>(ICS.UserDefined.ConversionFunction)) {
    QualType FromCanon
      = S.Context.getCanonicalType(From->getType().getUnqualifiedType());
    QualType ToCanon
      = S.Context.getCanonicalType(ToType).getUnqualifiedType();
    if (Constructor->isCopyConstructor() &&
        (FromCanon == ToCanon ||
         S.IsDerivedFrom(From->getBeginLoc(), FromCanon, ToCanon))) {
      // Turn this into a "standard" conversion sequence, so that it
      // gets ranked with standard conversion sequences.
      DeclAccessPair Found = ICS.UserDefined.FoundConversionFunction;
      ICS.setStandard();
      ICS.Standard.setAsIdentityConversion();
      ICS.Standard.setFromType(From->getType());
      ICS.Standard.setAllToTypes(ToType);
      ICS.Standard.CopyConstructor = Constructor;
      ICS.Standard.FoundCopyConstructor = Found;
      if (ToCanon != FromCanon)
        ICS.Standard.Second = ICK_Derived_To_Base;
    }
  }
  break;

case OR_Ambiguous:
  ICS.setAmbiguous();
  ICS.Ambiguous.setFromType(From->getType());
  ICS.Ambiguous.setToType(ToType);
  for (OverloadCandidateSet::iterator Cand = Conversions.begin();
       Cand != Conversions.end(); ++Cand)
    if (Cand->Best)
      ICS.Ambiguous.addConversion(Cand->FoundDecl, Cand->Function);
  break;

  // Fall through.
case OR_No_Viable_Function:
  ICS.setBad(BadConversionSequence::no_conversion, From, ToType);
  break;
}

return ICS;
1395}

1397/// TryImplicitConversion - Attempt to perform an implicit conversion
1398/// from the given expression (Expr) to the given type (ToType). This
1399/// function returns an implicit conversion sequence that can be used
1400/// to perform the initialization. Given
1401///
1402///   void f(float f);
1403///   void g(int i) { f(i); }
1404///
1405/// this routine would produce an implicit conversion sequence to
1406/// describe the initialization of f from i, which will be a standard
1407/// conversion sequence containing an lvalue-to-rvalue conversion (C++
1408/// 4.1) followed by a floating-integral conversion (C++ 4.9).
1409//
1410/// Note that this routine only determines how the conversion can be
1411/// performed; it does not actually perform the conversion. As such,
1412/// it will not produce any diagnostics if no conversion is available,
1413/// but will instead return an implicit conversion sequence of kind
1414/// "BadConversion".
1415///
1416/// If @p SuppressUserConversions, then user-defined conversions are
1417/// not permitted.
1418/// If @p AllowExplicit, then explicit user-defined conversions are
1419/// permitted.
1420///
1421/// \param AllowObjCWritebackConversion Whether we allow the Objective-C
1422/// writeback conversion, which allows __autoreleasing id* parameters to
1423/// be initialized with __strong id* or __weak id* arguments.
1424static ImplicitConversionSequence
1425TryImplicitConversion(Sema &S, Expr *From, QualType ToType,
                    bool SuppressUserConversions,
                    AllowedExplicit AllowExplicit,
                    bool InOverloadResolution,
                    bool CStyle,
                    bool AllowObjCWritebackConversion,
                    bool AllowObjCConversionOnExplicit) {
ImplicitConversionSequence ICS;
if (IsStandardConversion(S, From, ToType, InOverloadResolution,
                         ICS.Standard, CStyle, AllowObjCWritebackConversion)){
  ICS.setStandard();
  return ICS;
}

if (!S.getLangOpts().CPlusPlus) {
  ICS.setBad(BadConversionSequence::no_conversion, From, ToType);
  return ICS;
}

// C++ [over.ics.user]p4:
//   A conversion of an expression of class type to the same class
//   type is given Exact Match rank, and a conversion of an
//   expression of class type to a base class of that type is
//   given Conversion rank, in spite of the fact that a copy/move
//   constructor (i.e., a user-defined conversion function) is
//   called for those cases.
QualType FromType = From->getType();
if (ToType->getAs<RecordType>() && FromType->getAs<RecordType>() &&
    (S.Context.hasSameUnqualifiedType(FromType, ToType) ||
     S.IsDerivedFrom(From->getBeginLoc(), FromType, ToType))) {
  ICS.setStandard();
  ICS.Standard.setAsIdentityConversion();
  ICS.Standard.setFromType(FromType);
  ICS.Standard.setAllToTypes(ToType);

  // We don't actually check at this point whether there is a valid
  // copy/move constructor, since overloading just assumes that it
  // exists. When we actually perform initialization, we'll find the
  // appropriate constructor to copy the returned object, if needed.
  ICS.Standard.CopyConstructor = nullptr;

  // Determine whether this is considered a derived-to-base conversion.
  if (!S.Context.hasSameUnqualifiedType(FromType, ToType))
    ICS.Standard.Second = ICK_Derived_To_Base;

  return ICS;
}

return TryUserDefinedConversion(S, From, ToType, SuppressUserConversions,
                                AllowExplicit, InOverloadResolution, CStyle,
                                AllowObjCWritebackConversion,
                                AllowObjCConversionOnExplicit);
1477}

1479ImplicitConversionSequence
1480Sema::TryImplicitConversion(Expr *From, QualType ToType,
                          bool SuppressUserConversions,
                          AllowedExplicit AllowExplicit,
                          bool InOverloadResolution,
                          bool CStyle,
                          bool AllowObjCWritebackConversion) {
return ::TryImplicitConversion(*this, From, ToType, SuppressUserConversions,
                               AllowExplicit, InOverloadResolution, CStyle,
                               AllowObjCWritebackConversion,
                               /*AllowObjCConversionOnExplicit=*/false);
1490}

1492/// PerformImplicitConversion - Perform an implicit conversion of the
1493/// expression From to the type ToType. Returns the
1494/// converted expression. Flavor is the kind of conversion we're
1495/// performing, used in the error message. If @p AllowExplicit,
1496/// explicit user-defined conversions are permitted.
1497ExprResult Sema::PerformImplicitConversion(Expr *From, QualType ToType,
                                         AssignmentAction Action,
                                         bool AllowExplicit) {
if (checkPlaceholderForOverload(*this, From))
  return ExprError();

// Objective-C ARC: Determine whether we will allow the writeback conversion.
bool AllowObjCWritebackConversion
  = getLangOpts().ObjCAutoRefCount &&
    (Action == AA_Passing || Action == AA_Sending);
if (getLangOpts().ObjC)
  CheckObjCBridgeRelatedConversions(From->getBeginLoc(), ToType,
                                    From->getType(), From);
ImplicitConversionSequence ICS = ::TryImplicitConversion(
    *this, From, ToType,
    /*SuppressUserConversions=*/false,
    AllowExplicit ? AllowedExplicit::All : AllowedExplicit::None,
    /*InOverloadResolution=*/false,
    /*CStyle=*/false, AllowObjCWritebackConversion,
    /*AllowObjCConversionOnExplicit=*/false);
return PerformImplicitConversion(From, ToType, ICS, Action);
1518}

1520/// Determine whether the conversion from FromType to ToType is a valid
1521/// conversion that strips "noexcept" or "noreturn" off the nested function
1522/// type.
1523bool Sema::IsFunctionConversion(QualType FromType, QualType ToType,
                              QualType &ResultTy) {
if (Context.hasSameUnqualifiedType(FromType, ToType))
  return false;

// Permit the conversion F(t __attribute__((noreturn))) -> F(t)
//                    or F(t noexcept) -> F(t)
// where F adds one of the following at most once:
//   - a pointer
//   - a member pointer
//   - a block pointer
// Changes here need matching changes in FindCompositePointerType.
CanQualType CanTo = Context.getCanonicalType(ToType);
CanQualType CanFrom = Context.getCanonicalType(FromType);
Type::TypeClass TyClass = CanTo->getTypeClass();
if (TyClass != CanFrom->getTypeClass()) return false;
if (TyClass != Type::FunctionProto && TyClass != Type::FunctionNoProto) {
  if (TyClass == Type::Pointer) {
    CanTo = CanTo.castAs<PointerType>()->getPointeeType();
    CanFrom = CanFrom.castAs<PointerType>()->getPointeeType();
  } else if (TyClass == Type::BlockPointer) {
    CanTo = CanTo.castAs<BlockPointerType>()->getPointeeType();
    CanFrom = CanFrom.castAs<BlockPointerType>()->getPointeeType();
  } else if (TyClass == Type::MemberPointer) {
    auto ToMPT = CanTo.castAs<MemberPointerType>();
    auto FromMPT = CanFrom.castAs<MemberPointerType>();
    // A function pointer conversion cannot change the class of the function.
    if (ToMPT->getClass() != FromMPT->getClass())
      return false;
    CanTo = ToMPT->getPointeeType();
    CanFrom = FromMPT->getPointeeType();
  } else {
    return false;
  }

  TyClass = CanTo->getTypeClass();
  if (TyClass != CanFrom->getTypeClass()) return false;
  if (TyClass != Type::FunctionProto && TyClass != Type::FunctionNoProto)
    return false;
}

const auto *FromFn = cast<FunctionType>(CanFrom);
FunctionType::ExtInfo FromEInfo = FromFn->getExtInfo();

const auto *ToFn = cast<FunctionType>(CanTo);
FunctionType::ExtInfo ToEInfo = ToFn->getExtInfo();

bool Changed = false;

// Drop 'noreturn' if not present in target type.
if (FromEInfo.getNoReturn() && !ToEInfo.getNoReturn()) {
  FromFn = Context.adjustFunctionType(FromFn, FromEInfo.withNoReturn(false));
  Changed = true;
}

// Drop 'noexcept' if not present in target type.
if (const auto *FromFPT = dyn_cast<FunctionProtoType>(FromFn)) {
  const auto *ToFPT = cast<FunctionProtoType>(ToFn);
  if (FromFPT->isNothrow() && !ToFPT->isNothrow()) {
    FromFn = cast<FunctionType>(
        Context.getFunctionTypeWithExceptionSpec(QualType(FromFPT, 0),
                                                 EST_None)
               .getTypePtr());
    Changed = true;
  }

  // Convert FromFPT's ExtParameterInfo if necessary. The conversion is valid
  // only if the ExtParameterInfo lists of the two function prototypes can be
  // merged and the merged list is identical to ToFPT's ExtParameterInfo list.
  SmallVector<FunctionProtoType::ExtParameterInfo, 4> NewParamInfos;
  bool CanUseToFPT, CanUseFromFPT;
  if (Context.mergeExtParameterInfo(ToFPT, FromFPT, CanUseToFPT,
                                    CanUseFromFPT, NewParamInfos) &&
      CanUseToFPT && !CanUseFromFPT) {
    FunctionProtoType::ExtProtoInfo ExtInfo = FromFPT->getExtProtoInfo();
    ExtInfo.ExtParameterInfos =
        NewParamInfos.empty() ? nullptr : NewParamInfos.data();
    QualType QT = Context.getFunctionType(FromFPT->getReturnType(),
                                          FromFPT->getParamTypes(), ExtInfo);
    FromFn = QT->getAs<FunctionType>();
    Changed = true;
  }
}

if (!Changed)
  return false;

assert(QualType(FromFn, 0).isCanonical())((void)0);
if (QualType(FromFn, 0) != CanTo) return false;

ResultTy = ToType;
return true;
1615}

1617/// Determine whether the conversion from FromType to ToType is a valid
1618/// vector conversion.
1619///
1620/// \param ICK Will be set to the vector conversion kind, if this is a vector
1621/// conversion.
1622static bool IsVectorConversion(Sema &S, QualType FromType,
                             QualType ToType, ImplicitConversionKind &ICK) {
// We need at least one of these types to be a vector type to have a vector
// conversion.
if (!ToType->isVectorType() && !FromType->isVectorType())
  return false;

// Identical types require no conversions.
if (S.Context.hasSameUnqualifiedType(FromType, ToType))
  return false;

// There are no conversions between extended vector types, only identity.
if (ToType->isExtVectorType()) {
  // There are no conversions between extended vector types other than the
  // identity conversion.
  if (FromType->isExtVectorType())
    return false;

  // Vector splat from any arithmetic type to a vector.
  if (FromType->isArithmeticType()) {
    ICK = ICK_Vector_Splat;
    return true;
  }
}

if (ToType->isSizelessBuiltinType() || FromType->isSizelessBuiltinType())
  if (S.Context.areCompatibleSveTypes(FromType, ToType) ||
      S.Context.areLaxCompatibleSveTypes(FromType, ToType)) {
    ICK = ICK_SVE_Vector_Conversion;
    return true;
  }

// We can perform the conversion between vector types in the following cases:
// 1)vector types are equivalent AltiVec and GCC vector types
// 2)lax vector conversions are permitted and the vector types are of the
//   same size
// 3)the destination type does not have the ARM MVE strict-polymorphism
//   attribute, which inhibits lax vector conversion for overload resolution
//   only
if (ToType->isVectorType() && FromType->isVectorType()) {
  if (S.Context.areCompatibleVectorTypes(FromType, ToType) ||
      (S.isLaxVectorConversion(FromType, ToType) &&
       !ToType->hasAttr(attr::ArmMveStrictPolymorphism))) {
    ICK = ICK_Vector_Conversion;
    return true;
  }
}

return false;
1671}

1673static bool tryAtomicConversion(Sema &S, Expr *From, QualType ToType,
                              bool InOverloadResolution,
                              StandardConversionSequence &SCS,
                              bool CStyle);

1678/// IsStandardConversion - Determines whether there is a standard
1679/// conversion sequence (C++ [conv], C++ [over.ics.scs]) from the
1680/// expression From to the type ToType. Standard conversion sequences
1681/// only consider non-class types; for conversions that involve class
1682/// types, use TryImplicitConversion. If a conversion exists, SCS will
1683/// contain the standard conversion sequence required to perform this
1684/// conversion and this routine will return true. Otherwise, this
1685/// routine will return false and the value of SCS is unspecified.
1686static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
                               bool InOverloadResolution,
                               StandardConversionSequence &SCS,
                               bool CStyle,
                               bool AllowObjCWritebackConversion) {
QualType FromType = From->getType();

// Standard conversions (C++ [conv])
SCS.setAsIdentityConversion();
SCS.IncompatibleObjC = false;
SCS.setFromType(FromType);
SCS.CopyConstructor = nullptr;

// There are no standard conversions for class types in C++, so
// abort early. When overloading in C, however, we do permit them.
if (S.getLangOpts().CPlusPlus &&
    (FromType->isRecordType() || ToType->isRecordType()))
  return false;

// The first conversion can be an lvalue-to-rvalue conversion,
// array-to-pointer conversion, or function-to-pointer conversion
// (C++ 4p1).

if (FromType == S.Context.OverloadTy) {
  DeclAccessPair AccessPair;
  if (FunctionDecl *Fn
        = S.ResolveAddressOfOverloadedFunction(From, ToType, false,
                                               AccessPair)) {
    // We were able to resolve the address of the overloaded function,
    // so we can convert to the type of that function.
    FromType = Fn->getType();
    SCS.setFromType(FromType);

    // we can sometimes resolve &foo<int> regardless of ToType, so check
    // if the type matches (identity) or we are converting to bool
    if (!S.Context.hasSameUnqualifiedType(
                    S.ExtractUnqualifiedFunctionType(ToType), FromType)) {
      QualType resultTy;
      // if the function type matches except for [[noreturn]], it's ok
      if (!S.IsFunctionConversion(FromType,
            S.ExtractUnqualifiedFunctionType(ToType), resultTy))
        // otherwise, only a boolean conversion is standard
        if (!ToType->isBooleanType())
          return false;
    }

    // Check if the "from" expression is taking the address of an overloaded
    // function and recompute the FromType accordingly. Take advantage of the
    // fact that non-static member functions *must* have such an address-of
    // expression.
    CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn);
    if (Method && !Method->isStatic()) {
      assert(isa<UnaryOperator>(From->IgnoreParens()) &&((void)0)
             "Non-unary operator on non-static member address")((void)0);
      assert(cast<UnaryOperator>(From->IgnoreParens())->getOpcode()((void)0)
             == UO_AddrOf &&((void)0)
             "Non-address-of operator on non-static member address")((void)0);
      const Type *ClassType
        = S.Context.getTypeDeclType(Method->getParent()).getTypePtr();
      FromType = S.Context.getMemberPointerType(FromType, ClassType);
    } else if (isa<UnaryOperator>(From->IgnoreParens())) {
      assert(cast<UnaryOperator>(From->IgnoreParens())->getOpcode() ==((void)0)
             UO_AddrOf &&((void)0)
             "Non-address-of operator for overloaded function expression")((void)0);
      FromType = S.Context.getPointerType(FromType);
    }

    // Check that we've computed the proper type after overload resolution.
    // FIXME: FixOverloadedFunctionReference has side-effects; we shouldn't
    // be calling it from within an NDEBUG block.
    assert(S.Context.hasSameType(((void)0)
      FromType,((void)0)
      S.FixOverloadedFunctionReference(From, AccessPair, Fn)->getType()))((void)0);
  } else {
    return false;
  }
}
// Lvalue-to-rvalue conversion (C++11 4.1):
//   A glvalue (3.10) of a non-function, non-array type T can
//   be converted to a prvalue.
bool argIsLValue = From->isGLValue();
if (argIsLValue &&
    !FromType->isFunctionType() && !FromType->isArrayType() &&
    S.Context.getCanonicalType(FromType) != S.Context.OverloadTy) {
  SCS.First = ICK_Lvalue_To_Rvalue;

  // C11 6.3.2.1p2:
  //   ... if the lvalue has atomic type, the value has the non-atomic version
  //   of the type of the lvalue ...
  if (const AtomicType *Atomic = FromType->getAs<AtomicType>())
    FromType = Atomic->getValueType();

  // If T is a non-class type, the type of the rvalue is the
  // cv-unqualified version of T. Otherwise, the type of the rvalue
  // is T (C++ 4.1p1). C++ can't get here with class types; in C, we
  // just strip the qualifiers because they don't matter.
  FromType = FromType.getUnqualifiedType();
} else if (FromType->isArrayType()) {
  // Array-to-pointer conversion (C++ 4.2)
  SCS.First = ICK_Array_To_Pointer;

  // An lvalue or rvalue of type "array of N T" or "array of unknown
  // bound of T" can be converted to an rvalue of type "pointer to
  // T" (C++ 4.2p1).
  FromType = S.Context.getArrayDecayedType(FromType);

  if (S.IsStringLiteralToNonConstPointerConversion(From, ToType)) {
    // This conversion is deprecated in C++03 (D.4)
    SCS.DeprecatedStringLiteralToCharPtr = true;

    // For the purpose of ranking in overload resolution
    // (13.3.3.1.1), this conversion is considered an
    // array-to-pointer conversion followed by a qualification
    // conversion (4.4). (C++ 4.2p2)
    SCS.Second = ICK_Identity;
    SCS.Third = ICK_Qualification;
    SCS.QualificationIncludesObjCLifetime = false;
    SCS.setAllToTypes(FromType);
    return true;
  }
} else if (FromType->isFunctionType() && argIsLValue) {
  // Function-to-pointer conversion (C++ 4.3).
  SCS.First = ICK_Function_To_Pointer;

  if (auto *DRE = dyn_cast<DeclRefExpr>(From->IgnoreParenCasts()))
    if (auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl()))
      if (!S.checkAddressOfFunctionIsAvailable(FD))
        return false;

  // An lvalue of function type T can be converted to an rvalue of
  // type "pointer to T." The result is a pointer to the
  // function. (C++ 4.3p1).
  FromType = S.Context.getPointerType(FromType);
} else {
  // We don't require any conversions for the first step.
  SCS.First = ICK_Identity;
}
SCS.setToType(0, FromType);

// The second conversion can be an integral promotion, floating
// point promotion, integral conversion, floating point conversion,
// floating-integral conversion, pointer conversion,
// pointer-to-member conversion, or boolean conversion (C++ 4p1).
// For overloading in C, this can also be a "compatible-type"
// conversion.
bool IncompatibleObjC = false;
ImplicitConversionKind SecondICK = ICK_Identity;
if (S.Context.hasSameUnqualifiedType(FromType, ToType)) {
  // The unqualified versions of the types are the same: there's no
  // conversion to do.
  SCS.Second = ICK_Identity;
} else if (S.IsIntegralPromotion(From, FromType, ToType)) {
  // Integral promotion (C++ 4.5).
  SCS.Second = ICK_Integral_Promotion;
  FromType = ToType.getUnqualifiedType();
} else if (S.IsFloatingPointPromotion(FromType, ToType)) {
  // Floating point promotion (C++ 4.6).
  SCS.Second = ICK_Floating_Promotion;
  FromType = ToType.getUnqualifiedType();
} else if (S.IsComplexPromotion(FromType, ToType)) {
  // Complex promotion (Clang extension)
  SCS.Second = ICK_Complex_Promotion;
  FromType = ToType.getUnqualifiedType();
} else if (ToType->isBooleanType() &&
           (FromType->isArithmeticType() ||
            FromType->isAnyPointerType() ||
            FromType->isBlockPointerType() ||
            FromType->isMemberPointerType())) {
  // Boolean conversions (C++ 4.12).
  SCS.Second = ICK_Boolean_Conversion;
  FromType = S.Context.BoolTy;
} else if (FromType->isIntegralOrUnscopedEnumerationType() &&
           ToType->isIntegralType(S.Context)) {
  // Integral conversions (C++ 4.7).
  SCS.Second = ICK_Integral_Conversion;
  FromType = ToType.getUnqualifiedType();
} else if (FromType->isAnyComplexType() && ToType->isAnyComplexType()) {
  // Complex conversions (C99 6.3.1.6)
  SCS.Second = ICK_Complex_Conversion;
  FromType = ToType.getUnqualifiedType();
} else if ((FromType->isAnyComplexType() && ToType->isArithmeticType()) ||
           (ToType->isAnyComplexType() && FromType->isArithmeticType())) {
  // Complex-real conversions (C99 6.3.1.7)
  SCS.Second = ICK_Complex_Real;
  FromType = ToType.getUnqualifiedType();
} else if (FromType->isRealFloatingType() && ToType->isRealFloatingType()) {
  // FIXME: disable conversions between long double and __float128 if
  // their representation is different until there is back end support
  // We of course allow this conversion if long double is really double.

  // Conversions between bfloat and other floats are not permitted.
  if (FromType == S.Context.BFloat16Ty || ToType == S.Context.BFloat16Ty)
    return false;
  if (&S.Context.getFloatTypeSemantics(FromType) !=
      &S.Context.getFloatTypeSemantics(ToType)) {
    bool Float128AndLongDouble = ((FromType == S.Context.Float128Ty &&
                                  ToType == S.Context.LongDoubleTy) ||
                                 (FromType == S.Context.LongDoubleTy &&
                                  ToType == S.Context.Float128Ty));
    if (Float128AndLongDouble &&
        (&S.Context.getFloatTypeSemantics(S.Context.LongDoubleTy) ==
         &llvm::APFloat::PPCDoubleDouble()))
      return false;
  }
  // Floating point conversions (C++ 4.8).
  SCS.Second = ICK_Floating_Conversion;
  FromType = ToType.getUnqualifiedType();
} else if ((FromType->isRealFloatingType() &&
            ToType->isIntegralType(S.Context)) ||
           (FromType->isIntegralOrUnscopedEnumerationType() &&
            ToType->isRealFloatingType())) {
  // Conversions between bfloat and int are not permitted.
  if (FromType->isBFloat16Type() || ToType->isBFloat16Type())
    return false;

  // Floating-integral conversions (C++ 4.9).
  SCS.Second = ICK_Floating_Integral;
  FromType = ToType.getUnqualifiedType();
} else if (S.IsBlockPointerConversion(FromType, ToType, FromType)) {
  SCS.Second = ICK_Block_Pointer_Conversion;
} else if (AllowObjCWritebackConversion &&
           S.isObjCWritebackConversion(FromType, ToType, FromType)) {
  SCS.Second = ICK_Writeback_Conversion;
} else if (S.IsPointerConversion(From, FromType, ToType, InOverloadResolution,
                                 FromType, IncompatibleObjC)) {
  // Pointer conversions (C++ 4.10).
  SCS.Second = ICK_Pointer_Conversion;
  SCS.IncompatibleObjC = IncompatibleObjC;
  FromType = FromType.getUnqualifiedType();
} else if (S.IsMemberPointerConversion(From, FromType, ToType,
                                       InOverloadResolution, FromType)) {
  // Pointer to member conversions (4.11).
  SCS.Second = ICK_Pointer_Member;
} else if (IsVectorConversion(S, FromType, ToType, SecondICK)) {
  SCS.Second = SecondICK;
  FromType = ToType.getUnqualifiedType();
} else if (!S.getLangOpts().CPlusPlus &&
           S.Context.typesAreCompatible(ToType, FromType)) {
  // Compatible conversions (Clang extension for C function overloading)
  SCS.Second = ICK_Compatible_Conversion;
  FromType = ToType.getUnqualifiedType();
} else if (IsTransparentUnionStandardConversion(S, From, ToType,
                                           InOverloadResolution,
                                           SCS, CStyle)) {
  SCS.Second = ICK_TransparentUnionConversion;
  FromType = ToType;
} else if (tryAtomicConversion(S, From, ToType, InOverloadResolution, SCS,
                               CStyle)) {
  // tryAtomicConversion has updated the standard conversion sequence
  // appropriately.
  return true;
} else if (ToType->isEventT() &&
           From->isIntegerConstantExpr(S.getASTContext()) &&
           From->EvaluateKnownConstInt(S.getASTContext()) == 0) {
  SCS.Second = ICK_Zero_Event_Conversion;
  FromType = ToType;
} else if (ToType->isQueueT() &&
           From->isIntegerConstantExpr(S.getASTContext()) &&
           (From->EvaluateKnownConstInt(S.getASTContext()) == 0)) {
  SCS.Second = ICK_Zero_Queue_Conversion;
  FromType = ToType;
} else if (ToType->isSamplerT() &&
           From->isIntegerConstantExpr(S.getASTContext())) {
  SCS.Second = ICK_Compatible_Conversion;
  FromType = ToType;
} else {
  // No second conversion required.
  SCS.Second = ICK_Identity;
}
SCS.setToType(1, FromType);

// The third conversion can be a function pointer conversion or a
// qualification conversion (C++ [conv.fctptr], [conv.qual]).
bool ObjCLifetimeConversion;
if (S.IsFunctionConversion(FromType, ToType, FromType)) {
  // Function pointer conversions (removing 'noexcept') including removal of
  // 'noreturn' (Clang extension).
  SCS.Third = ICK_Function_Conversion;
} else if (S.IsQualificationConversion(FromType, ToType, CStyle,
                                       ObjCLifetimeConversion)) {
  SCS.Third = ICK_Qualification;
  SCS.QualificationIncludesObjCLifetime = ObjCLifetimeConversion;
  FromType = ToType;
} else {
  // No conversion required
  SCS.Third = ICK_Identity;
}

// C++ [over.best.ics]p6:
//   [...] Any difference in top-level cv-qualification is
//   subsumed by the initialization itself and does not constitute
//   a conversion. [...]
QualType CanonFrom = S.Context.getCanonicalType(FromType);
QualType CanonTo = S.Context.getCanonicalType(ToType);
if (CanonFrom.getLocalUnqualifiedType()
                                   == CanonTo.getLocalUnqualifiedType() &&
    CanonFrom.getLocalQualifiers() != CanonTo.getLocalQualifiers()) {
  FromType = ToType;
  CanonFrom = CanonTo;
}

SCS.setToType(2, FromType);

if (CanonFrom == CanonTo)
  return true;

// If we have not converted the argument type to the parameter type,
// this is a bad conversion sequence, unless we're resolving an overload in C.
if (S.getLangOpts().CPlusPlus || !InOverloadResolution)
  return false;

ExprResult ER = ExprResult{From};
Sema::AssignConvertType Conv =
    S.CheckSingleAssignmentConstraints(ToType, ER,
                                       /*Diagnose=*/false,
                                       /*DiagnoseCFAudited=*/false,
                                       /*ConvertRHS=*/false);
ImplicitConversionKind SecondConv;
switch (Conv) {
case Sema::Compatible:
  SecondConv = ICK_C_Only_Conversion;
  break;
// For our purposes, discarding qualifiers is just as bad as using an
// incompatible pointer. Note that an IncompatiblePointer conversion can drop
// qualifiers, as well.
case Sema::CompatiblePointerDiscardsQualifiers:
case Sema::IncompatiblePointer:
case Sema::IncompatiblePointerSign:
  SecondConv = ICK_Incompatible_Pointer_Conversion;
  break;
default:
  return false;
}

// First can only be an lvalue conversion, so we pretend that this was the
// second conversion. First should already be valid from earlier in the
// function.
SCS.Second = SecondConv;
SCS.setToType(1, ToType);

// Third is Identity, because Second should rank us worse than any other
// conversion. This could also be ICK_Qualification, but it's simpler to just
// lump everything in with the second conversion, and we don't gain anything
// from making this ICK_Qualification.
SCS.Third = ICK_Identity;
SCS.setToType(2, ToType);
return true;
2033}

2035static bool
2036IsTransparentUnionStandardConversion(Sema &S, Expr* From,
                                   QualType &ToType,
                                   bool InOverloadResolution,
                                   StandardConversionSequence &SCS,
                                   bool CStyle) {

const RecordType *UT = ToType->getAsUnionType();
if (!UT || !UT->getDecl()->hasAttr<TransparentUnionAttr>())
  return false;
// The field to initialize within the transparent union.
RecordDecl *UD = UT->getDecl();
// It's compatible if the expression matches any of the fields.
for (const auto *it : UD->fields()) {
  if (IsStandardConversion(S, From, it->getType(), InOverloadResolution, SCS,
                           CStyle, /*AllowObjCWritebackConversion=*/false)) {
    ToType = it->getType();
    return true;
  }
}
return false;
2056}

2058/// IsIntegralPromotion - Determines whether the conversion from the
2059/// expression From (whose potentially-adjusted type is FromType) to
2060/// ToType is an integral promotion (C++ 4.5). If so, returns true and
2061/// sets PromotedType to the promoted type.
2062bool Sema::IsIntegralPromotion(Expr *From, QualType FromType, QualType ToType) {
const BuiltinType *To = ToType->getAs<BuiltinType>();
// All integers are built-in.
if (!To) {
  return false;
}

// An rvalue of type char, signed char, unsigned char, short int, or
// unsigned short int can be converted to an rvalue of type int if
// int can represent all the values of the source type; otherwise,
// the source rvalue can be converted to an rvalue of type unsigned
// int (C++ 4.5p1).
if (FromType->isPromotableIntegerType() && !FromType->isBooleanType() &&
    !FromType->isEnumeralType()) {
  if (// We can promote any signed, promotable integer type to an int
      (FromType->isSignedIntegerType() ||
       // We can promote any unsigned integer type whose size is
       // less than int to an int.
       Context.getTypeSize(FromType) < Context.getTypeSize(ToType))) {
    return To->getKind() == BuiltinType::Int;
  }

  return To->getKind() == BuiltinType::UInt;
}

// C++11 [conv.prom]p3:
//   A prvalue of an unscoped enumeration type whose underlying type is not
//   fixed (7.2) can be converted to an rvalue a prvalue of the first of the
//   following types that can represent all the values of the enumeration
//   (i.e., the values in the range bmin to bmax as described in 7.2): int,
//   unsigned int, long int, unsigned long int, long long int, or unsigned
//   long long int. If none of the types in that list can represent all the
//   values of the enumeration, an rvalue a prvalue of an unscoped enumeration
//   type can be converted to an rvalue a prvalue of the extended integer type
//   with lowest integer conversion rank (4.13) greater than the rank of long
//   long in which all the values of the enumeration can be represented. If
//   there are two such extended types, the signed one is chosen.
// C++11 [conv.prom]p4:
//   A prvalue of an unscoped enumeration type whose underlying type is fixed
//   can be converted to a prvalue of its underlying type. Moreover, if
//   integral promotion can be applied to its underlying type, a prvalue of an
//   unscoped enumeration type whose underlying type is fixed can also be
//   converted to a prvalue of the promoted underlying type.
if (const EnumType *FromEnumType = FromType->getAs<EnumType>()) {
  // C++0x 7.2p9: Note that this implicit enum to int conversion is not
  // provided for a scoped enumeration.
  if (FromEnumType->getDecl()->isScoped())
    return false;

  // We can perform an integral promotion to the underlying type of the enum,
  // even if that's not the promoted type. Note that the check for promoting
  // the underlying type is based on the type alone, and does not consider
  // the bitfield-ness of the actual source expression.
  if (FromEnumType->getDecl()->isFixed()) {
    QualType Underlying = FromEnumType->getDecl()->getIntegerType();
    return Context.hasSameUnqualifiedType(Underlying, ToType) ||
           IsIntegralPromotion(nullptr, Underlying, ToType);
  }

  // We have already pre-calculated the promotion type, so this is trivial.
  if (ToType->isIntegerType() &&
      isCompleteType(From->getBeginLoc(), FromType))
    return Context.hasSameUnqualifiedType(
        ToType, FromEnumType->getDecl()->getPromotionType());

  // C++ [conv.prom]p5:
  //   If the bit-field has an enumerated type, it is treated as any other
  //   value of that type for promotion purposes.
  //
  // ... so do not fall through into the bit-field checks below in C++.
  if (getLangOpts().CPlusPlus)
    return false;
}

// C++0x [conv.prom]p2:
//   A prvalue of type char16_t, char32_t, or wchar_t (3.9.1) can be converted
//   to an rvalue a prvalue of the first of the following types that can
//   represent all the values of its underlying type: int, unsigned int,
//   long int, unsigned long int, long long int, or unsigned long long int.
//   If none of the types in that list can represent all the values of its
//   underlying type, an rvalue a prvalue of type char16_t, char32_t,
//   or wchar_t can be converted to an rvalue a prvalue of its underlying
//   type.
if (FromType->isAnyCharacterType() && !FromType->isCharType() &&
    ToType->isIntegerType()) {
  // Determine whether the type we're converting from is signed or
  // unsigned.
  bool FromIsSigned = FromType->isSignedIntegerType();
  uint64_t FromSize = Context.getTypeSize(FromType);

  // The types we'll try to promote to, in the appropriate
  // order. Try each of these types.
  QualType PromoteTypes[6] = {
    Context.IntTy, Context.UnsignedIntTy,
    Context.LongTy, Context.UnsignedLongTy ,
    Context.LongLongTy, Context.UnsignedLongLongTy
  };
  for (int Idx = 0; Idx < 6; ++Idx) {
    uint64_t ToSize = Context.getTypeSize(PromoteTypes[Idx]);
    if (FromSize < ToSize ||
        (FromSize == ToSize &&
         FromIsSigned == PromoteTypes[Idx]->isSignedIntegerType())) {
      // We found the type that we can promote to. If this is the
      // type we wanted, we have a promotion. Otherwise, no
      // promotion.
      return Context.hasSameUnqualifiedType(ToType, PromoteTypes[Idx]);
    }
  }
}

// An rvalue for an integral bit-field (9.6) can be converted to an
// rvalue of type int if int can represent all the values of the
// bit-field; otherwise, it can be converted to unsigned int if
// unsigned int can represent all the values of the bit-field. If
// the bit-field is larger yet, no integral promotion applies to
// it. If the bit-field has an enumerated type, it is treated as any
// other value of that type for promotion purposes (C++ 4.5p3).
// FIXME: We should delay checking of bit-fields until we actually perform the
// conversion.
//
// FIXME: In C, only bit-fields of types _Bool, int, or unsigned int may be
// promoted, per C11 6.3.1.1/2. We promote all bit-fields (including enum
// bit-fields and those whose underlying type is larger than int) for GCC
// compatibility.
if (From) {
  if (FieldDecl *MemberDecl = From->getSourceBitField()) {
    Optional<llvm::APSInt> BitWidth;
    if (FromType->isIntegralType(Context) &&
        (BitWidth =
             MemberDecl->getBitWidth()->getIntegerConstantExpr(Context))) {
      llvm::APSInt ToSize(BitWidth->getBitWidth(), BitWidth->isUnsigned());
      ToSize = Context.getTypeSize(ToType);

      // Are we promoting to an int from a bitfield that fits in an int?
      if (*BitWidth < ToSize ||
          (FromType->isSignedIntegerType() && *BitWidth <= ToSize)) {
        return To->getKind() == BuiltinType::Int;
      }

      // Are we promoting to an unsigned int from an unsigned bitfield
      // that fits into an unsigned int?
      if (FromType->isUnsignedIntegerType() && *BitWidth <= ToSize) {
        return To->getKind() == BuiltinType::UInt;
      }

      return false;
    }
  }
}

// An rvalue of type bool can be converted to an rvalue of type int,
// with false becoming zero and true becoming one (C++ 4.5p4).
if (FromType->isBooleanType() && To->getKind() == BuiltinType::Int) {
  return true;
}

return false;
2219}

2221/// IsFloatingPointPromotion - Determines whether the conversion from
2222/// FromType to ToType is a floating point promotion (C++ 4.6). If so,
2223/// returns true and sets PromotedType to the promoted type.
2224bool Sema::IsFloatingPointPromotion(QualType FromType, QualType ToType) {
if (const BuiltinType *FromBuiltin = FromType->getAs<BuiltinType>())
  if (const BuiltinType *ToBuiltin = ToType->getAs<BuiltinType>()) {
    /// An rvalue of type float can be converted to an rvalue of type
    /// double. (C++ 4.6p1).
    if (FromBuiltin->getKind() == BuiltinType::Float &&
        ToBuiltin->getKind() == BuiltinType::Double)
      return true;

    // C99 6.3.1.5p1:
    //   When a float is promoted to double or long double, or a
    //   double is promoted to long double [...].
    if (!getLangOpts().CPlusPlus &&
        (FromBuiltin->getKind() == BuiltinType::Float ||
         FromBuiltin->getKind() == BuiltinType::Double) &&
        (ToBuiltin->getKind() == BuiltinType::LongDouble ||
         ToBuiltin->getKind() == BuiltinType::Float128))
      return true;

    // Half can be promoted to float.
    if (!getLangOpts().NativeHalfType &&
         FromBuiltin->getKind() == BuiltinType::Half &&
        ToBuiltin->getKind() == BuiltinType::Float)
      return true;
  }

return false;
2251}

2253/// Determine if a conversion is a complex promotion.
2254///
2255/// A complex promotion is defined as a complex -> complex conversion
2256/// where the conversion between the underlying real types is a
2257/// floating-point or integral promotion.
2258bool Sema::IsComplexPromotion(QualType FromType, QualType ToType) {
const ComplexType *FromComplex = FromType->getAs<ComplexType>();
if (!FromComplex)
  return false;

const ComplexType *ToComplex = ToType->getAs<ComplexType>();
if (!ToComplex)
  return false;

return IsFloatingPointPromotion(FromComplex->getElementType(),
                                ToComplex->getElementType()) ||
  IsIntegralPromotion(nullptr, FromComplex->getElementType(),
                      ToComplex->getElementType());
2271}

2273/// BuildSimilarlyQualifiedPointerType - In a pointer conversion from
2274/// the pointer type FromPtr to a pointer to type ToPointee, with the
2275/// same type qualifiers as FromPtr has on its pointee type. ToType,
2276/// if non-empty, will be a pointer to ToType that may or may not have
2277/// the right set of qualifiers on its pointee.
2278///
2279static QualType
2280BuildSimilarlyQualifiedPointerType(const Type *FromPtr,
                                 QualType ToPointee, QualType ToType,
                                 ASTContext &Context,
                                 bool StripObjCLifetime = false) {
assert((FromPtr->getTypeClass() == Type::Pointer ||((void)0)
        FromPtr->getTypeClass() == Type::ObjCObjectPointer) &&((void)0)
       "Invalid similarly-qualified pointer type")((void)0);

/// Conversions to 'id' subsume cv-qualifier conversions.
if (ToType->isObjCIdType() || ToType->isObjCQualifiedIdType())
  return ToType.getUnqualifiedType();

QualType CanonFromPointee
  = Context.getCanonicalType(FromPtr->getPointeeType());
QualType CanonToPointee = Context.getCanonicalType(ToPointee);
Qualifiers Quals = CanonFromPointee.getQualifiers();

if (StripObjCLifetime)
  Quals.removeObjCLifetime();

// Exact qualifier match -> return the pointer type we're converting to.
if (CanonToPointee.getLocalQualifiers() == Quals) {
  // ToType is exactly what we need. Return it.
  if (!ToType.isNull())
    return ToType.getUnqualifiedType();

  // Build a pointer to ToPointee. It has the right qualifiers
  // already.
  if (isa<ObjCObjectPointerType>(ToType))
    return Context.getObjCObjectPointerType(ToPointee);
  return Context.getPointerType(ToPointee);
}

// Just build a canonical type that has the right qualifiers.
QualType QualifiedCanonToPointee
  = Context.getQualifiedType(CanonToPointee.getLocalUnqualifiedType(), Quals);

if (isa<ObjCObjectPointerType>(ToType))
  return Context.getObjCObjectPointerType(QualifiedCanonToPointee);
return Context.getPointerType(QualifiedCanonToPointee);
2320}

2322static bool isNullPointerConstantForConversion(Expr *Expr,
                                             bool InOverloadResolution,
                                             ASTContext &Context) {
// Handle value-dependent integral null pointer constants correctly.
// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#903
if (Expr->isValueDependent() && !Expr->isTypeDependent() &&
    Expr->getType()->isIntegerType() && !Expr->getType()->isEnumeralType())
  return !InOverloadResolution;

return Expr->isNullPointerConstant(Context,
                  InOverloadResolution? Expr::NPC_ValueDependentIsNotNull
                                      : Expr::NPC_ValueDependentIsNull);
2334}

2336/// IsPointerConversion - Determines whether the conversion of the
2337/// expression From, which has the (possibly adjusted) type FromType,
2338/// can be converted to the type ToType via a pointer conversion (C++
2339/// 4.10). If so, returns true and places the converted type (that
2340/// might differ from ToType in its cv-qualifiers at some level) into
2341/// ConvertedType.
2342///
2343/// This routine also supports conversions to and from block pointers
2344/// and conversions with Objective-C's 'id', 'id<protocols...>', and
2345/// pointers to interfaces. FIXME: Once we've determined the
2346/// appropriate overloading rules for Objective-C, we may want to
2347/// split the Objective-C checks into a different routine; however,
2348/// GCC seems to consider all of these conversions to be pointer
2349/// conversions, so for now they live here. IncompatibleObjC will be
2350/// set if the conversion is an allowed Objective-C conversion that
2351/// should result in a warning.
2352bool Sema::IsPointerConversion(Expr *From, QualType FromType, QualType ToType,
                             bool InOverloadResolution,
                             QualType& ConvertedType,
                             bool &IncompatibleObjC) {
IncompatibleObjC = false;
if (isObjCPointerConversion(FromType, ToType, ConvertedType,
                            IncompatibleObjC))
  return true;

// Conversion from a null pointer constant to any Objective-C pointer type.
if (ToType->isObjCObjectPointerType() &&
    isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

// Blocks: Block pointers can be converted to void*.
if (FromType->isBlockPointerType() && ToType->isPointerType() &&
    ToType->castAs<PointerType>()->getPointeeType()->isVoidType()) {
  ConvertedType = ToType;
  return true;
}
// Blocks: A null pointer constant can be converted to a block
// pointer type.
if (ToType->isBlockPointerType() &&
    isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

// If the left-hand-side is nullptr_t, the right side can be a null
// pointer constant.
if (ToType->isNullPtrType() &&
    isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

const PointerType* ToTypePtr = ToType->getAs<PointerType>();
if (!ToTypePtr)
  return false;

// A null pointer constant can be converted to a pointer type (C++ 4.10p1).
if (isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

// Beyond this point, both types need to be pointers
// , including objective-c pointers.
QualType ToPointeeType = ToTypePtr->getPointeeType();
if (FromType->isObjCObjectPointerType() && ToPointeeType->isVoidType() &&
    !getLangOpts().ObjCAutoRefCount) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(
                                    FromType->getAs<ObjCObjectPointerType>(),
                                                     ToPointeeType,
                                                     ToType, Context);
  return true;
}
const PointerType *FromTypePtr = FromType->getAs<PointerType>();
if (!FromTypePtr)
  return false;

QualType FromPointeeType = FromTypePtr->getPointeeType();

// If the unqualified pointee types are the same, this can't be a
// pointer conversion, so don't do all of the work below.
if (Context.hasSameUnqualifiedType(FromPointeeType, ToPointeeType))
  return false;

// An rvalue of type "pointer to cv T," where T is an object type,
// can be converted to an rvalue of type "pointer to cv void" (C++
// 4.10p2).
if (FromPointeeType->isIncompleteOrObjectType() &&
    ToPointeeType->isVoidType()) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(FromTypePtr,
                                                     ToPointeeType,
                                                     ToType, Context,
                                                 /*StripObjCLifetime=*/true);
  return true;
}

// MSVC allows implicit function to void* type conversion.
if (getLangOpts().MSVCCompat && FromPointeeType->isFunctionType() &&
    ToPointeeType->isVoidType()) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(FromTypePtr,
                                                     ToPointeeType,
                                                     ToType, Context);
  return true;
}

// When we're overloading in C, we allow a special kind of pointer
// conversion for compatible-but-not-identical pointee types.
if (!getLangOpts().CPlusPlus &&
    Context.typesAreCompatible(FromPointeeType, ToPointeeType)) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(FromTypePtr,
                                                     ToPointeeType,
                                                     ToType, Context);
  return true;
}

// C++ [conv.ptr]p3:
//
//   An rvalue of type "pointer to cv D," where D is a class type,
//   can be converted to an rvalue of type "pointer to cv B," where
//   B is a base class (clause 10) of D. If B is an inaccessible
//   (clause 11) or ambiguous (10.2) base class of D, a program that
//   necessitates this conversion is ill-formed. The result of the
//   conversion is a pointer to the base class sub-object of the
//   derived class object. The null pointer value is converted to
//   the null pointer value of the destination type.
//
// Note that we do not check for ambiguity or inaccessibility
// here. That is handled by CheckPointerConversion.
if (getLangOpts().CPlusPlus && FromPointeeType->isRecordType() &&
    ToPointeeType->isRecordType() &&
    !Context.hasSameUnqualifiedType(FromPointeeType, ToPointeeType) &&
    IsDerivedFrom(From->getBeginLoc(), FromPointeeType, ToPointeeType)) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(FromTypePtr,
                                                     ToPointeeType,
                                                     ToType, Context);
  return true;
}

if (FromPointeeType->isVectorType() && ToPointeeType->isVectorType() &&
    Context.areCompatibleVectorTypes(FromPointeeType, ToPointeeType)) {
  ConvertedType = BuildSimilarlyQualifiedPointerType(FromTypePtr,
                                                     ToPointeeType,
                                                     ToType, Context);
  return true;
}

return false;
2485}

2487/// Adopt the given qualifiers for the given type.
2488static QualType AdoptQualifiers(ASTContext &Context, QualType T, Qualifiers Qs){
Qualifiers TQs = T.getQualifiers();

// Check whether qualifiers already match.
if (TQs == Qs)
  return T;

if (Qs.compatiblyIncludes(TQs))
  return Context.getQualifiedType(T, Qs);

return Context.getQualifiedType(T.getUnqualifiedType(), Qs);
2499}

2501/// isObjCPointerConversion - Determines whether this is an
2502/// Objective-C pointer conversion. Subroutine of IsPointerConversion,
2503/// with the same arguments and return values.
2504bool Sema::isObjCPointerConversion(QualType FromType, QualType ToType,
                                 QualType& ConvertedType,
                                 bool &IncompatibleObjC) {
if (!getLangOpts().ObjC)
  return false;

// The set of qualifiers on the type we're converting from.
Qualifiers FromQualifiers = FromType.getQualifiers();

// First, we handle all conversions on ObjC object pointer types.
const ObjCObjectPointerType* ToObjCPtr =
  ToType->getAs<ObjCObjectPointerType>();
const ObjCObjectPointerType *FromObjCPtr =
  FromType->getAs<ObjCObjectPointerType>();

if (ToObjCPtr && FromObjCPtr) {
  // If the pointee types are the same (ignoring qualifications),
  // then this is not a pointer conversion.
  if (Context.hasSameUnqualifiedType(ToObjCPtr->getPointeeType(),
                                     FromObjCPtr->getPointeeType()))
    return false;

  // Conversion between Objective-C pointers.
  if (Context.canAssignObjCInterfaces(ToObjCPtr, FromObjCPtr)) {
    const ObjCInterfaceType* LHS = ToObjCPtr->getInterfaceType();
    const ObjCInterfaceType* RHS = FromObjCPtr->getInterfaceType();
    if (getLangOpts().CPlusPlus && LHS && RHS &&
        !ToObjCPtr->getPointeeType().isAtLeastAsQualifiedAs(
                                              FromObjCPtr->getPointeeType()))
      return false;
    ConvertedType = BuildSimilarlyQualifiedPointerType(FromObjCPtr,
                                                 ToObjCPtr->getPointeeType(),
                                                       ToType, Context);
    ConvertedType = AdoptQualifiers(Context, ConvertedType, FromQualifiers);
    return true;
  }

  if (Context.canAssignObjCInterfaces(FromObjCPtr, ToObjCPtr)) {
    // Okay: this is some kind of implicit downcast of Objective-C
    // interfaces, which is permitted. However, we're going to
    // complain about it.
    IncompatibleObjC = true;
    ConvertedType = BuildSimilarlyQualifiedPointerType(FromObjCPtr,
                                                 ToObjCPtr->getPointeeType(),
                                                       ToType, Context);
    ConvertedType = AdoptQualifiers(Context, ConvertedType, FromQualifiers);
    return true;
  }
}
// Beyond this point, both types need to be C pointers or block pointers.
QualType ToPointeeType;
if (const PointerType *ToCPtr = ToType->getAs<PointerType>())
  ToPointeeType = ToCPtr->getPointeeType();
else if (const BlockPointerType *ToBlockPtr =
          ToType->getAs<BlockPointerType>()) {
  // Objective C++: We're able to convert from a pointer to any object
  // to a block pointer type.
  if (FromObjCPtr && FromObjCPtr->isObjCBuiltinType()) {
    ConvertedType = AdoptQualifiers(Context, ToType, FromQualifiers);
    return true;
  }
  ToPointeeType = ToBlockPtr->getPointeeType();
}
else if (FromType->getAs<BlockPointerType>() &&
         ToObjCPtr && ToObjCPtr->isObjCBuiltinType()) {
  // Objective C++: We're able to convert from a block pointer type to a
  // pointer to any object.
  ConvertedType = AdoptQualifiers(Context, ToType, FromQualifiers);
  return true;
}
else
  return false;

QualType FromPointeeType;
if (const PointerType *FromCPtr = FromType->getAs<PointerType>())
  FromPointeeType = FromCPtr->getPointeeType();
else if (const BlockPointerType *FromBlockPtr =
         FromType->getAs<BlockPointerType>())
  FromPointeeType = FromBlockPtr->getPointeeType();
else
  return false;

// If we have pointers to pointers, recursively check whether this
// is an Objective-C conversion.
if (FromPointeeType->isPointerType() && ToPointeeType->isPointerType() &&
    isObjCPointerConversion(FromPointeeType, ToPointeeType, ConvertedType,
                            IncompatibleObjC)) {
  // We always complain about this conversion.
  IncompatibleObjC = true;
  ConvertedType = Context.getPointerType(ConvertedType);
  ConvertedType = AdoptQualifiers(Context, ConvertedType, FromQualifiers);
  return true;
}
// Allow conversion of pointee being objective-c pointer to another one;
// as in I* to id.
if (FromPointeeType->getAs<ObjCObjectPointerType>() &&
    ToPointeeType->getAs<ObjCObjectPointerType>() &&
    isObjCPointerConversion(FromPointeeType, ToPointeeType, ConvertedType,
                            IncompatibleObjC)) {

  ConvertedType = Context.getPointerType(ConvertedType);
  ConvertedType = AdoptQualifiers(Context, ConvertedType, FromQualifiers);
  return true;
}

// If we have pointers to functions or blocks, check whether the only
// differences in the argument and result types are in Objective-C
// pointer conversions. If so, we permit the conversion (but
// complain about it).
const FunctionProtoType *FromFunctionType
  = FromPointeeType->getAs<FunctionProtoType>();
const FunctionProtoType *ToFunctionType
  = ToPointeeType->getAs<FunctionProtoType>();
if (FromFunctionType && ToFunctionType) {
  // If the function types are exactly the same, this isn't an
  // Objective-C pointer conversion.
  if (Context.getCanonicalType(FromPointeeType)
        == Context.getCanonicalType(ToPointeeType))
    return false;

  // Perform the quick checks that will tell us whether these
  // function types are obviously different.
  if (FromFunctionType->getNumParams() != ToFunctionType->getNumParams() ||
      FromFunctionType->isVariadic() != ToFunctionType->isVariadic() ||
      FromFunctionType->getMethodQuals() != ToFunctionType->getMethodQuals())
    return false;

  bool HasObjCConversion = false;
  if (Context.getCanonicalType(FromFunctionType->getReturnType()) ==
      Context.getCanonicalType(ToFunctionType->getReturnType())) {
    // Okay, the types match exactly. Nothing to do.
  } else if (isObjCPointerConversion(FromFunctionType->getReturnType(),
                                     ToFunctionType->getReturnType(),
                                     ConvertedType, IncompatibleObjC)) {
    // Okay, we have an Objective-C pointer conversion.
    HasObjCConversion = true;
  } else {
    // Function types are too different. Abort.
    return false;
  }

  // Check argument types.
  for (unsigned ArgIdx = 0, NumArgs = FromFunctionType->getNumParams();
       ArgIdx != NumArgs; ++ArgIdx) {
    QualType FromArgType = FromFunctionType->getParamType(ArgIdx);
    QualType ToArgType = ToFunctionType->getParamType(ArgIdx);
    if (Context.getCanonicalType(FromArgType)
          == Context.getCanonicalType(ToArgType)) {
      // Okay, the types match exactly. Nothing to do.
    } else if (isObjCPointerConversion(FromArgType, ToArgType,
                                       ConvertedType, IncompatibleObjC)) {
      // Okay, we have an Objective-C pointer conversion.
      HasObjCConversion = true;
    } else {
      // Argument types are too different. Abort.
      return false;
    }
  }

  if (HasObjCConversion) {
    // We had an Objective-C conversion. Allow this pointer
    // conversion, but complain about it.
    ConvertedType = AdoptQualifiers(Context, ToType, FromQualifiers);
    IncompatibleObjC = true;
    return true;
  }
}

return false;
2673}

2675/// Determine whether this is an Objective-C writeback conversion,
2676/// used for parameter passing when performing automatic reference counting.
2677///
2678/// \param FromType The type we're converting form.
2679///
2680/// \param ToType The type we're converting to.
2681///
2682/// \param ConvertedType The type that will be produced after applying
2683/// this conversion.
2684bool Sema::isObjCWritebackConversion(QualType FromType, QualType ToType,
                                   QualType &ConvertedType) {
if (!getLangOpts().ObjCAutoRefCount ||
    Context.hasSameUnqualifiedType(FromType, ToType))
  return false;

// Parameter must be a pointer to __autoreleasing (with no other qualifiers).
QualType ToPointee;
if (const PointerType *ToPointer = ToType->getAs<PointerType>())
  ToPointee = ToPointer->getPointeeType();
else
  return false;

Qualifiers ToQuals = ToPointee.getQualifiers();
if (!ToPointee->isObjCLifetimeType() ||
    ToQuals.getObjCLifetime() != Qualifiers::OCL_Autoreleasing ||
    !ToQuals.withoutObjCLifetime().empty())
  return false;

// Argument must be a pointer to __strong to __weak.
QualType FromPointee;
if (const PointerType *FromPointer = FromType->getAs<PointerType>())
  FromPointee = FromPointer->getPointeeType();
else
  return false;

Qualifiers FromQuals = FromPointee.getQualifiers();
if (!FromPointee->isObjCLifetimeType() ||
    (FromQuals.getObjCLifetime() != Qualifiers::OCL_Strong &&
     FromQuals.getObjCLifetime() != Qualifiers::OCL_Weak))
  return false;

// Make sure that we have compatible qualifiers.
FromQuals.setObjCLifetime(Qualifiers::OCL_Autoreleasing);
if (!ToQuals.compatiblyIncludes(FromQuals))
  return false;

// Remove qualifiers from the pointee type we're converting from; they
// aren't used in the compatibility check belong, and we'll be adding back
// qualifiers (with __autoreleasing) if the compatibility check succeeds.
FromPointee = FromPointee.getUnqualifiedType();

// The unqualified form of the pointee types must be compatible.
ToPointee = ToPointee.getUnqualifiedType();
bool IncompatibleObjC;
if (Context.typesAreCompatible(FromPointee, ToPointee))
  FromPointee = ToPointee;
else if (!isObjCPointerConversion(FromPointee, ToPointee, FromPointee,
                                  IncompatibleObjC))
  return false;

/// Construct the type we're converting to, which is a pointer to
/// __autoreleasing pointee.
FromPointee = Context.getQualifiedType(FromPointee, FromQuals);
ConvertedType = Context.getPointerType(FromPointee);
return true;
2740}

2742bool Sema::IsBlockPointerConversion(QualType FromType, QualType ToType,
                                  QualType& ConvertedType) {
QualType ToPointeeType;
if (const BlockPointerType *ToBlockPtr =
      ToType->getAs<BlockPointerType>())
  ToPointeeType = ToBlockPtr->getPointeeType();
else
  return false;

QualType FromPointeeType;
if (const BlockPointerType *FromBlockPtr =
    FromType->getAs<BlockPointerType>())
  FromPointeeType = FromBlockPtr->getPointeeType();
else
  return false;
// We have pointer to blocks, check whether the only
// differences in the argument and result types are in Objective-C
// pointer conversions. If so, we permit the conversion.

const FunctionProtoType *FromFunctionType
  = FromPointeeType->getAs<FunctionProtoType>();
const FunctionProtoType *ToFunctionType
  = ToPointeeType->getAs<FunctionProtoType>();

if (!FromFunctionType || !ToFunctionType)
  return false;

if (Context.hasSameType(FromPointeeType, ToPointeeType))
  return true;

// Perform the quick checks that will tell us whether these
// function types are obviously different.
if (FromFunctionType->getNumParams() != ToFunctionType->getNumParams() ||
    FromFunctionType->isVariadic() != ToFunctionType->isVariadic())
  return false;

FunctionType::ExtInfo FromEInfo = FromFunctionType->getExtInfo();
FunctionType::ExtInfo ToEInfo = ToFunctionType->getExtInfo();
if (FromEInfo != ToEInfo)
  return false;

bool IncompatibleObjC = false;
if (Context.hasSameType(FromFunctionType->getReturnType(),
                        ToFunctionType->getReturnType())) {
  // Okay, the types match exactly. Nothing to do.
} else {
  QualType RHS = FromFunctionType->getReturnType();
  QualType LHS = ToFunctionType->getReturnType();
  if ((!getLangOpts().CPlusPlus || !RHS->isRecordType()) &&
      !RHS.hasQualifiers() && LHS.hasQualifiers())
     LHS = LHS.getUnqualifiedType();

   if (Context.hasSameType(RHS,LHS)) {
     // OK exact match.
   } else if (isObjCPointerConversion(RHS, LHS,
                                      ConvertedType, IncompatibleObjC)) {
   if (IncompatibleObjC)
     return false;
   // Okay, we have an Objective-C pointer conversion.
   }
   else
     return false;
 }

 // Check argument types.
 for (unsigned ArgIdx = 0, NumArgs = FromFunctionType->getNumParams();
      ArgIdx != NumArgs; ++ArgIdx) {
   IncompatibleObjC = false;
   QualType FromArgType = FromFunctionType->getParamType(ArgIdx);
   QualType ToArgType = ToFunctionType->getParamType(ArgIdx);
   if (Context.hasSameType(FromArgType, ToArgType)) {
     // Okay, the types match exactly. Nothing to do.
   } else if (isObjCPointerConversion(ToArgType, FromArgType,
                                      ConvertedType, IncompatibleObjC)) {
     if (IncompatibleObjC)
       return false;
     // Okay, we have an Objective-C pointer conversion.
   } else
     // Argument types are too different. Abort.
     return false;
 }

 SmallVector<FunctionProtoType::ExtParameterInfo, 4> NewParamInfos;
 bool CanUseToFPT, CanUseFromFPT;
 if (!Context.mergeExtParameterInfo(ToFunctionType, FromFunctionType,
                                    CanUseToFPT, CanUseFromFPT,
                                    NewParamInfos))
   return false;

 ConvertedType = ToType;
 return true;
2833}

2835enum {
ft_default,
ft_different_class,
ft_parameter_arity,
ft_parameter_mismatch,
ft_return_type,
ft_qualifer_mismatch,
ft_noexcept
2843};

2845/// Attempts to get the FunctionProtoType from a Type. Handles
2846/// MemberFunctionPointers properly.
2847static const FunctionProtoType *tryGetFunctionProtoType(QualType FromType) {
if (auto *FPT = FromType->getAs<FunctionProtoType>())
  return FPT;

if (auto *MPT = FromType->getAs<MemberPointerType>())
  return MPT->getPointeeType()->getAs<FunctionProtoType>();

return nullptr;
2855}

2857/// HandleFunctionTypeMismatch - Gives diagnostic information for differeing
2858/// function types.  Catches different number of parameter, mismatch in
2859/// parameter types, and different return types.
2860void Sema::HandleFunctionTypeMismatch(PartialDiagnostic &PDiag,
                                    QualType FromType, QualType ToType) {
// If either type is not valid, include no extra info.
if (FromType.isNull() || ToType.isNull()) {
  PDiag << ft_default;
  return;
}

// Get the function type from the pointers.
if (FromType->isMemberPointerType() && ToType->isMemberPointerType()) {
  const auto *FromMember = FromType->castAs<MemberPointerType>(),
             *ToMember = ToType->castAs<MemberPointerType>();
  if (!Context.hasSameType(FromMember->getClass(), ToMember->getClass())) {
    PDiag << ft_different_class << QualType(ToMember->getClass(), 0)
          << QualType(FromMember->getClass(), 0);
    return;
  }
  FromType = FromMember->getPointeeType();
  ToType = ToMember->getPointeeType();
}

if (FromType->isPointerType())
  FromType = FromType->getPointeeType();
if (ToType->isPointerType())
  ToType = ToType->getPointeeType();

// Remove references.
FromType = FromType.getNonReferenceType();
ToType = ToType.getNonReferenceType();

// Don't print extra info for non-specialized template functions.
if (FromType->isInstantiationDependentType() &&
    !FromType->getAs<TemplateSpecializationType>()) {
  PDiag << ft_default;
  return;
}

// No extra info for same types.
if (Context.hasSameType(FromType, ToType)) {
  PDiag << ft_default;
  return;
}

const FunctionProtoType *FromFunction = tryGetFunctionProtoType(FromType),
                        *ToFunction = tryGetFunctionProtoType(ToType);

// Both types need to be function types.
if (!FromFunction || !ToFunction) {
  PDiag << ft_default;
  return;
}

if (FromFunction->getNumParams() != ToFunction->getNumParams()) {
  PDiag << ft_parameter_arity << ToFunction->getNumParams()
        << FromFunction->getNumParams();
  return;
}

// Handle different parameter types.
unsigned ArgPos;
if (!FunctionParamTypesAreEqual(FromFunction, ToFunction, &ArgPos)) {
  PDiag << ft_parameter_mismatch << ArgPos + 1
        << ToFunction->getParamType(ArgPos)
        << FromFunction->getParamType(ArgPos);
  return;
}

// Handle different return type.
if (!Context.hasSameType(FromFunction->getReturnType(),
                         ToFunction->getReturnType())) {
  PDiag << ft_return_type << ToFunction->getReturnType()
        << FromFunction->getReturnType();
  return;
}

if (FromFunction->getMethodQuals() != ToFunction->getMethodQuals()) {
  PDiag << ft_qualifer_mismatch << ToFunction->getMethodQuals()
        << FromFunction->getMethodQuals();
  return;
}

// Handle exception specification differences on canonical type (in C++17
// onwards).
if (cast<FunctionProtoType>(FromFunction->getCanonicalTypeUnqualified())
        ->isNothrow() !=
    cast<FunctionProtoType>(ToFunction->getCanonicalTypeUnqualified())
        ->isNothrow()) {
  PDiag << ft_noexcept;
  return;
}

// Unable to find a difference, so add no extra info.
PDiag << ft_default;
2953}

2955/// FunctionParamTypesAreEqual - This routine checks two function proto types
2956/// for equality of their argument types. Caller has already checked that
2957/// they have same number of arguments.  If the parameters are different,
2958/// ArgPos will have the parameter index of the first different parameter.
2959bool Sema::FunctionParamTypesAreEqual(const FunctionProtoType *OldType,
                                    const FunctionProtoType *NewType,
                                    unsigned *ArgPos) {
for (FunctionProtoType::param_type_iterator O = OldType->param_type_begin(),
                                            N = NewType->param_type_begin(),
                                            E = OldType->param_type_end();
     O && (O != E); ++O, ++N) {
  // Ignore address spaces in pointee type. This is to disallow overloading
  // on __ptr32/__ptr64 address spaces.
  QualType Old = Context.removePtrSizeAddrSpace(O->getUnqualifiedType());
  QualType New = Context.removePtrSizeAddrSpace(N->getUnqualifiedType());

  if (!Context.hasSameType(Old, New)) {
    if (ArgPos)
      *ArgPos = O - OldType->param_type_begin();
    return false;
  }
}
return true;
2978}

2980/// CheckPointerConversion - Check the pointer conversion from the
2981/// expression From to the type ToType. This routine checks for
2982/// ambiguous or inaccessible derived-to-base pointer
2983/// conversions for which IsPointerConversion has already returned
2984/// true. It returns true and produces a diagnostic if there was an
2985/// error, or returns false otherwise.
2986bool Sema::CheckPointerConversion(Expr *From, QualType ToType,
                                CastKind &Kind,
                                CXXCastPath& BasePath,
                                bool IgnoreBaseAccess,
                                bool Diagnose) {
QualType FromType = From->getType();
bool IsCStyleOrFunctionalCast = IgnoreBaseAccess;

Kind = CK_BitCast;

if (Diagnose && !IsCStyleOrFunctionalCast && !FromType->isAnyPointerType() &&
    From->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull) ==
        Expr::NPCK_ZeroExpression) {
  if (Context.hasSameUnqualifiedType(From->getType(), Context.BoolTy))
    DiagRuntimeBehavior(From->getExprLoc(), From,
                        PDiag(diag::warn_impcast_bool_to_null_pointer)
                          << ToType << From->getSourceRange());
  else if (!isUnevaluatedContext())
    Diag(From->getExprLoc(), diag::warn_non_literal_null_pointer)
      << ToType << From->getSourceRange();
}
if (const PointerType *ToPtrType = ToType->getAs<PointerType>()) {
  if (const PointerType *FromPtrType = FromType->getAs<PointerType>()) {
    QualType FromPointeeType = FromPtrType->getPointeeType(),
             ToPointeeType   = ToPtrType->getPointeeType();

    if (FromPointeeType->isRecordType() && ToPointeeType->isRecordType() &&
        !Context.hasSameUnqualifiedType(FromPointeeType, ToPointeeType)) {
      // We must have a derived-to-base conversion. Check an
      // ambiguous or inaccessible conversion.
      unsigned InaccessibleID = 0;
      unsigned AmbiguousID = 0;
      if (Diagnose) {
        InaccessibleID = diag::err_upcast_to_inaccessible_base;
        AmbiguousID = diag::err_ambiguous_derived_to_base_conv;
      }
      if (CheckDerivedToBaseConversion(
              FromPointeeType, ToPointeeType, InaccessibleID, AmbiguousID,
              From->getExprLoc(), From->getSourceRange(), DeclarationName(),
              &BasePath, IgnoreBaseAccess))
        return true;

      // The conversion was successful.
      Kind = CK_DerivedToBase;
    }

    if (Diagnose && !IsCStyleOrFunctionalCast &&
        FromPointeeType->isFunctionType() && ToPointeeType->isVoidType()) {
      assert(getLangOpts().MSVCCompat &&((void)0)
             "this should only be possible with MSVCCompat!")((void)0);
      Diag(From->getExprLoc(), diag::ext_ms_impcast_fn_obj)
          << From->getSourceRange();
    }
  }
} else if (const ObjCObjectPointerType *ToPtrType =
             ToType->getAs<ObjCObjectPointerType>()) {
  if (const ObjCObjectPointerType *FromPtrType =
        FromType->getAs<ObjCObjectPointerType>()) {
    // Objective-C++ conversions are always okay.
    // FIXME: We should have a different class of conversions for the
    // Objective-C++ implicit conversions.
    if (FromPtrType->isObjCBuiltinType() || ToPtrType->isObjCBuiltinType())
      return false;
  } else if (FromType->isBlockPointerType()) {
    Kind = CK_BlockPointerToObjCPointerCast;
  } else {
    Kind = CK_CPointerToObjCPointerCast;
  }
} else if (ToType->isBlockPointerType()) {
  if (!FromType->isBlockPointerType())
    Kind = CK_AnyPointerToBlockPointerCast;
}

// We shouldn't fall into this case unless it's valid for other
// reasons.
if (From->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull))
  Kind = CK_NullToPointer;

return false;
3065}

3067/// IsMemberPointerConversion - Determines whether the conversion of the
3068/// expression From, which has the (possibly adjusted) type FromType, can be
3069/// converted to the type ToType via a member pointer conversion (C++ 4.11).
3070/// If so, returns true and places the converted type (that might differ from
3071/// ToType in its cv-qualifiers at some level) into ConvertedType.
3072bool Sema::IsMemberPointerConversion(Expr *From, QualType FromType,
                                   QualType ToType,
                                   bool InOverloadResolution,
                                   QualType &ConvertedType) {
const MemberPointerType *ToTypePtr = ToType->getAs<MemberPointerType>();
if (!ToTypePtr)
  return false;

// A null pointer constant can be converted to a member pointer (C++ 4.11p1)
if (From->isNullPointerConstant(Context,
                  InOverloadResolution? Expr::NPC_ValueDependentIsNotNull
                                      : Expr::NPC_ValueDependentIsNull)) {
  ConvertedType = ToType;
  return true;
}

// Otherwise, both types have to be member pointers.
const MemberPointerType *FromTypePtr = FromType->getAs<MemberPointerType>();
if (!FromTypePtr)
  return false;

// A pointer to member of B can be converted to a pointer to member of D,
// where D is derived from B (C++ 4.11p2).
QualType FromClass(FromTypePtr->getClass(), 0);
QualType ToClass(ToTypePtr->getClass(), 0);

if (!Context.hasSameUnqualifiedType(FromClass, ToClass) &&
    IsDerivedFrom(From->getBeginLoc(), ToClass, FromClass)) {
  ConvertedType = Context.getMemberPointerType(FromTypePtr->getPointeeType(),
                                               ToClass.getTypePtr());
  return true;
}

return false;
3106}

3108/// CheckMemberPointerConversion - Check the member pointer conversion from the
3109/// expression From to the type ToType. This routine checks for ambiguous or
3110/// virtual or inaccessible base-to-derived member pointer conversions
3111/// for which IsMemberPointerConversion has already returned true. It returns
3112/// true and produces a diagnostic if there was an error, or returns false
3113/// otherwise.
3114bool Sema::CheckMemberPointerConversion(Expr *From, QualType ToType,
                                      CastKind &Kind,
                                      CXXCastPath &BasePath,
                                      bool IgnoreBaseAccess) {
QualType FromType = From->getType();
const MemberPointerType *FromPtrType = FromType->getAs<MemberPointerType>();
if (!FromPtrType) {
  // This must be a null pointer to member pointer conversion
  assert(From->isNullPointerConstant(Context,((void)0)
                                     Expr::NPC_ValueDependentIsNull) &&((void)0)
         "Expr must be null pointer constant!")((void)0);
  Kind = CK_NullToMemberPointer;
  return false;
}

const MemberPointerType *ToPtrType = ToType->getAs<MemberPointerType>();
assert(ToPtrType && "No member pointer cast has a target type "((void)0)
                    "that is not a member pointer.")((void)0);

QualType FromClass = QualType(FromPtrType->getClass(), 0);
QualType ToClass   = QualType(ToPtrType->getClass(), 0);

// FIXME: What about dependent types?
assert(FromClass->isRecordType() && "Pointer into non-class.")((void)0);
assert(ToClass->isRecordType() && "Pointer into non-class.")((void)0);

CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
                   /*DetectVirtual=*/true);
bool DerivationOkay =
    IsDerivedFrom(From->getBeginLoc(), ToClass, FromClass, Paths);
assert(DerivationOkay &&((void)0)
       "Should not have been called if derivation isn't OK.")((void)0);
(void)DerivationOkay;

if (Paths.isAmbiguous(Context.getCanonicalType(FromClass).
                                getUnqualifiedType())) {
  std::string PathDisplayStr = getAmbiguousPathsDisplayString(Paths);
  Diag(From->getExprLoc(), diag::err_ambiguous_memptr_conv)
    << 0 << FromClass << ToClass << PathDisplayStr << From->getSourceRange();
  return true;
}

if (const RecordType *VBase = Paths.getDetectedVirtual()) {
  Diag(From->getExprLoc(), diag::err_memptr_conv_via_virtual)
    << FromClass << ToClass << QualType(VBase, 0)
    << From->getSourceRange();
  return true;
}

if (!IgnoreBaseAccess)
  CheckBaseClassAccess(From->getExprLoc(), FromClass, ToClass,
                       Paths.front(),
                       diag::err_downcast_from_inaccessible_base);

// Must be a base to derived member conversion.
BuildBasePathArray(Paths, BasePath);
Kind = CK_BaseToDerivedMemberPointer;
return false;
3172}

3174/// Determine whether the lifetime conversion between the two given
3175/// qualifiers sets is nontrivial.
3176static bool isNonTrivialObjCLifetimeConversion(Qualifiers FromQuals,
                                             Qualifiers ToQuals) {
// Converting anything to const __unsafe_unretained is trivial.
if (ToQuals.hasConst() &&
    ToQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone)
  return false;

return true;
3184}

3186/// Perform a single iteration of the loop for checking if a qualification
3187/// conversion is valid.
3188///
3189/// Specifically, check whether any change between the qualifiers of \p
3190/// FromType and \p ToType is permissible, given knowledge about whether every
3191/// outer layer is const-qualified.
3192static bool isQualificationConversionStep(QualType FromType, QualType ToType,
                                        bool CStyle, bool IsTopLevel,
                                        bool &PreviousToQualsIncludeConst,
                                        bool &ObjCLifetimeConversion) {
Qualifiers FromQuals = FromType.getQualifiers();
Qualifiers ToQuals = ToType.getQualifiers();

// Ignore __unaligned qualifier if this type is void.
if (ToType.getUnqualifiedType()->isVoidType())
  FromQuals.removeUnaligned();

// Objective-C ARC:
//   Check Objective-C lifetime conversions.
if (FromQuals.getObjCLifetime() != ToQuals.getObjCLifetime()) {
  if (ToQuals.compatiblyIncludesObjCLifetime(FromQuals)) {
    if (isNonTrivialObjCLifetimeConversion(FromQuals, ToQuals))
      ObjCLifetimeConversion = true;
    FromQuals.removeObjCLifetime();
    ToQuals.removeObjCLifetime();
  } else {
    // Qualification conversions cannot cast between different
    // Objective-C lifetime qualifiers.
    return false;
  }
}

// Allow addition/removal of GC attributes but not changing GC attributes.
if (FromQuals.getObjCGCAttr() != ToQuals.getObjCGCAttr() &&
    (!FromQuals.hasObjCGCAttr() || !ToQuals.hasObjCGCAttr())) {
  FromQuals.removeObjCGCAttr();
  ToQuals.removeObjCGCAttr();
}

//   -- for every j > 0, if const is in cv 1,j then const is in cv
//      2,j, and similarly for volatile.
if (!CStyle && !ToQuals.compatiblyIncludes(FromQuals))
  return false;

// If address spaces mismatch:
//  - in top level it is only valid to convert to addr space that is a
//    superset in all cases apart from C-style casts where we allow
//    conversions between overlapping address spaces.
//  - in non-top levels it is not a valid conversion.
if (ToQuals.getAddressSpace() != FromQuals.getAddressSpace() &&
    (!IsTopLevel ||
     !(ToQuals.isAddressSpaceSupersetOf(FromQuals) ||
       (CStyle && FromQuals.isAddressSpaceSupersetOf(ToQuals)))))
  return false;

//   -- if the cv 1,j and cv 2,j are different, then const is in
//      every cv for 0 < k < j.
if (!CStyle && FromQuals.getCVRQualifiers() != ToQuals.getCVRQualifiers() &&
    !PreviousToQualsIncludeConst)
  return false;

// Keep track of whether all prior cv-qualifiers in the "to" type
// include const.
PreviousToQualsIncludeConst =
    PreviousToQualsIncludeConst && ToQuals.hasConst();
return true;
3252}

3254/// IsQualificationConversion - Determines whether the conversion from
3255/// an rvalue of type FromType to ToType is a qualification conversion
3256/// (C++ 4.4).
3257///
3258/// \param ObjCLifetimeConversion Output parameter that will be set to indicate
3259/// when the qualification conversion involves a change in the Objective-C
3260/// object lifetime.
3261bool
3262Sema::IsQualificationConversion(QualType FromType, QualType ToType,
                              bool CStyle, bool &ObjCLifetimeConversion) {
FromType = Context.getCanonicalType(FromType);
ToType = Context.getCanonicalType(ToType);
ObjCLifetimeConversion = false;

// If FromType and ToType are the same type, this is not a
// qualification conversion.
if (FromType.getUnqualifiedType() == ToType.getUnqualifiedType())
  return false;

// (C++ 4.4p4):
//   A conversion can add cv-qualifiers at levels other than the first
//   in multi-level pointers, subject to the following rules: [...]
bool PreviousToQualsIncludeConst = true;
bool UnwrappedAnyPointer = false;
while (Context.UnwrapSimilarTypes(FromType, ToType)) {
  if (!isQualificationConversionStep(
          FromType, ToType, CStyle, !UnwrappedAnyPointer,
          PreviousToQualsIncludeConst, ObjCLifetimeConversion))
    return false;
  UnwrappedAnyPointer = true;
}

// We are left with FromType and ToType being the pointee types
// after unwrapping the original FromType and ToType the same number
// of times. If we unwrapped any pointers, and if FromType and
// ToType have the same unqualified type (since we checked
// qualifiers above), then this is a qualification conversion.
return UnwrappedAnyPointer && Context.hasSameUnqualifiedType(FromType,ToType);
3292}

3294/// - Determine whether this is a conversion from a scalar type to an
3295/// atomic type.
3296///
3297/// If successful, updates \c SCS's second and third steps in the conversion
3298/// sequence to finish the conversion.
3299static bool tryAtomicConversion(Sema &S, Expr *From, QualType ToType,
                              bool InOverloadResolution,
                              StandardConversionSequence &SCS,
                              bool CStyle) {
const AtomicType *ToAtomic = ToType->getAs<AtomicType>();
if (!ToAtomic)
  return false;

StandardConversionSequence InnerSCS;
if (!IsStandardConversion(S, From, ToAtomic->getValueType(),
                          InOverloadResolution, InnerSCS,
                          CStyle, /*AllowObjCWritebackConversion=*/false))
  return false;

SCS.Second = InnerSCS.Second;
SCS.setToType(1, InnerSCS.getToType(1));
SCS.Third = InnerSCS.Third;
SCS.QualificationIncludesObjCLifetime
  = InnerSCS.QualificationIncludesObjCLifetime;
SCS.setToType(2, InnerSCS.getToType(2));
return true;
3320}

3322static bool isFirstArgumentCompatibleWithType(ASTContext &Context,
                                            CXXConstructorDecl *Constructor,
                                            QualType Type) {
const auto *CtorType = Constructor->getType()->castAs<FunctionProtoType>();
if (CtorType->getNumParams() > 0) {
  QualType FirstArg = CtorType->getParamType(0);
  if (Context.hasSameUnqualifiedType(Type, FirstArg.getNonReferenceType()))
    return true;
}
return false;
3332}

3334static OverloadingResult
3335IsInitializerListConstructorConversion(Sema &S, Expr *From, QualType ToType,
                                     CXXRecordDecl *To,
                                     UserDefinedConversionSequence &User,
                                     OverloadCandidateSet &CandidateSet,
                                     bool AllowExplicit) {
CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
for (auto *D : S.LookupConstructors(To)) {
  auto Info = getConstructorInfo(D);
  if (!Info)
    continue;

  bool Usable = !Info.Constructor->isInvalidDecl() &&
                S.isInitListConstructor(Info.Constructor);
  if (Usable) {
    bool SuppressUserConversions = false;
    if (Info.ConstructorTmpl)
      S.AddTemplateOverloadCandidate(Info.ConstructorTmpl, Info.FoundDecl,
                                     /*ExplicitArgs*/ nullptr, From,
                                     CandidateSet, SuppressUserConversions,
                                     /*PartialOverloading*/ false,
                                     AllowExplicit);
    else
      S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl, From,
                             CandidateSet, SuppressUserConversions,
                             /*PartialOverloading*/ false, AllowExplicit);
  }
}

bool HadMultipleCandidates = (CandidateSet.size() > 1);

OverloadCandidateSet::iterator Best;
switch (auto Result =
            CandidateSet.BestViableFunction(S, From->getBeginLoc(), Best)) {
case OR_Deleted:
case OR_Success: {
  // Record the standard conversion we used and the conversion function.
  CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(Best->Function);
  QualType ThisType = Constructor->getThisType();
  // Initializer lists don't have conversions as such.
  User.Before.setAsIdentityConversion();
  User.HadMultipleCandidates = HadMultipleCandidates;
  User.ConversionFunction = Constructor;
  User.FoundConversionFunction = Best->FoundDecl;
  User.After.setAsIdentityConversion();
  User.After.setFromType(ThisType->castAs<PointerType>()->getPointeeType());
  User.After.setAllToTypes(ToType);
  return Result;
}

case OR_No_Viable_Function:
  return OR_No_Viable_Function;
case OR_Ambiguous:
  return OR_Ambiguous;
}

llvm_unreachable("Invalid OverloadResult!")__builtin_unreachable();
3391}

3393/// Determines whether there is a user-defined conversion sequence
3394/// (C++ [over.ics.user]) that converts expression From to the type
3395/// ToType. If such a conversion exists, User will contain the
3396/// user-defined conversion sequence that performs such a conversion
3397/// and this routine will return true. Otherwise, this routine returns
3398/// false and User is unspecified.
3399///
3400/// \param AllowExplicit  true if the conversion should consider C++0x
3401/// "explicit" conversion functions as well as non-explicit conversion
3402/// functions (C++0x [class.conv.fct]p2).
3403///
3404/// \param AllowObjCConversionOnExplicit true if the conversion should
3405/// allow an extra Objective-C pointer conversion on uses of explicit
3406/// constructors. Requires \c AllowExplicit to also be set.
3407static OverloadingResult
3408IsUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
                      UserDefinedConversionSequence &User,
                      OverloadCandidateSet &CandidateSet,
                      AllowedExplicit AllowExplicit,
                      bool AllowObjCConversionOnExplicit) {
assert(AllowExplicit != AllowedExplicit::None ||((void)0)
       !AllowObjCConversionOnExplicit)((void)0);
CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);

// Whether we will only visit constructors.
bool ConstructorsOnly = false;

// If the type we are conversion to is a class type, enumerate its
// constructors.
if (const RecordType *ToRecordType = ToType->getAs<RecordType>()) {
  // C++ [over.match.ctor]p1:
  //   When objects of class type are direct-initialized (8.5), or
  //   copy-initialized from an expression of the same or a
  //   derived class type (8.5), overload resolution selects the
  //   constructor. [...] For copy-initialization, the candidate
  //   functions are all the converting constructors (12.3.1) of
  //   that class. The argument list is the expression-list within
  //   the parentheses of the initializer.
  if (S.Context.hasSameUnqualifiedType(ToType, From->getType()) ||
      (From->getType()->getAs<RecordType>() &&
       S.IsDerivedFrom(From->getBeginLoc(), From->getType(), ToType)))
    ConstructorsOnly = true;

  if (!S.isCompleteType(From->getExprLoc(), ToType)) {
    // We're not going to find any constructors.
  } else if (CXXRecordDecl *ToRecordDecl
               = dyn_cast<CXXRecordDecl>(ToRecordType->getDecl())) {

    Expr **Args = &From;
    unsigned NumArgs = 1;
    bool ListInitializing = false;
    if (InitListExpr *InitList = dyn_cast<InitListExpr>(From)) {
      // But first, see if there is an init-list-constructor that will work.
      OverloadingResult Result = IsInitializerListConstructorConversion(
          S, From, ToType, ToRecordDecl, User, CandidateSet,
          AllowExplicit == AllowedExplicit::All);
      if (Result != OR_No_Viable_Function)
        return Result;
      // Never mind.
      CandidateSet.clear(
          OverloadCandidateSet::CSK_InitByUserDefinedConversion);

      // If we're list-initializing, we pass the individual elements as
      // arguments, not the entire list.
      Args = InitList->getInits();
      NumArgs = InitList->getNumInits();
      ListInitializing = true;
    }

    for (auto *D : S.LookupConstructors(ToRecordDecl)) {
      auto Info = getConstructorInfo(D);
      if (!Info)
        continue;

      bool Usable = !Info.Constructor->isInvalidDecl();
      if (!ListInitializing)
        Usable = Usable && Info.Constructor->isConvertingConstructor(
                               /*AllowExplicit*/ true);
      if (Usable) {
        bool SuppressUserConversions = !ConstructorsOnly;
        // C++20 [over.best.ics.general]/4.5:
        //   if the target is the first parameter of a constructor [of class
        //   X] and the constructor [...] is a candidate by [...] the second
        //   phase of [over.match.list] when the initializer list has exactly
        //   one element that is itself an initializer list, [...] and the
        //   conversion is to X or reference to cv X, user-defined conversion
        //   sequences are not cnosidered.
        if (SuppressUserConversions && ListInitializing) {
          SuppressUserConversions =
              NumArgs == 1 && isa<InitListExpr>(Args[0]) &&
              isFirstArgumentCompatibleWithType(S.Context, Info.Constructor,
                                                ToType);
        }
        if (Info.ConstructorTmpl)
          S.AddTemplateOverloadCandidate(
              Info.ConstructorTmpl, Info.FoundDecl,
              /*ExplicitArgs*/ nullptr, llvm::makeArrayRef(Args, NumArgs),
              CandidateSet, SuppressUserConversions,
              /*PartialOverloading*/ false,
              AllowExplicit == AllowedExplicit::All);
        else
          // Allow one user-defined conversion when user specifies a
          // From->ToType conversion via an static cast (c-style, etc).
          S.AddOverloadCandidate(Info.Constructor, Info.FoundDecl,
                                 llvm::makeArrayRef(Args, NumArgs),
                                 CandidateSet, SuppressUserConversions,
                                 /*PartialOverloading*/ false,
                                 AllowExplicit == AllowedExplicit::All);
      }
    }
  }
}

// Enumerate conversion functions, if we're allowed to.
if (ConstructorsOnly || isa<InitListExpr>(From)) {
} else if (!S.isCompleteType(From->getBeginLoc(), From->getType())) {
  // No conversion functions from incomplete types.
} else if (const RecordType *FromRecordType =
               From->getType()->getAs<RecordType>()) {
  if (CXXRecordDecl *FromRecordDecl
       = dyn_cast<CXXRecordDecl>(FromRecordType->getDecl())) {
    // Add all of the conversion functions as candidates.
    const auto &Conversions = FromRecordDecl->getVisibleConversionFunctions();
    for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
      DeclAccessPair FoundDecl = I.getPair();
      NamedDecl *D = FoundDecl.getDecl();
      CXXRecordDecl *ActingContext = cast<CXXRecordDecl>(D->getDeclContext());
      if (isa<UsingShadowDecl>(D))
        D = cast<UsingShadowDecl>(D)->getTargetDecl();

      CXXConversionDecl *Conv;
      FunctionTemplateDecl *ConvTemplate;
      if ((ConvTemplate = dyn_cast<FunctionTemplateDecl>(D)))
        Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
      else
        Conv = cast<CXXConversionDecl>(D);

      if (ConvTemplate)
        S.AddTemplateConversionCandidate(
            ConvTemplate, FoundDecl, ActingContext, From, ToType,
            CandidateSet, AllowObjCConversionOnExplicit,
            AllowExplicit != AllowedExplicit::None);
      else
        S.AddConversionCandidate(Conv, FoundDecl, ActingContext, From, ToType,
                                 CandidateSet, AllowObjCConversionOnExplicit,
                                 AllowExplicit != AllowedExplicit::None);
    }
  }
}

bool HadMultipleCandidates = (CandidateSet.size() > 1);

OverloadCandidateSet::iterator Best;
switch (auto Result =
            CandidateSet.BestViableFunction(S, From->getBeginLoc(), Best)) {
case OR_Success:
case OR_Deleted:
  // Record the standard conversion we used and the conversion function.
  if (CXXConstructorDecl *Constructor
        = dyn_cast<CXXConstructorDecl>(Best->Function)) {
    // C++ [over.ics.user]p1:
    //   If the user-defined conversion is specified by a
    //   constructor (12.3.1), the initial standard conversion
    //   sequence converts the source type to the type required by
    //   the argument of the constructor.
    //
    QualType ThisType = Constructor->getThisType();
    if (isa<InitListExpr>(From)) {
      // Initializer lists don't have conversions as such.
      User.Before.setAsIdentityConversion();
    } else {
      if (Best->Conversions[0].isEllipsis())
        User.EllipsisConversion = true;
      else {
        User.Before = Best->Conversions[0].Standard;
        User.EllipsisConversion = false;
      }
    }
    User.HadMultipleCandidates = HadMultipleCandidates;
    User.ConversionFunction = Constructor;
    User.FoundConversionFunction = Best->FoundDecl;
    User.After.setAsIdentityConversion();
    User.After.setFromType(ThisType->castAs<PointerType>()->getPointeeType());
    User.After.setAllToTypes(ToType);
    return Result;
  }
  if (CXXConversionDecl *Conversion
               = dyn_cast<CXXConversionDecl>(Best->Function)) {
    // C++ [over.ics.user]p1:
    //
    //   [...] If the user-defined conversion is specified by a
    //   conversion function (12.3.2), the initial standard
    //   conversion sequence converts the source type to the
    //   implicit object parameter of the conversion function.
    User.Before = Best->Conversions[0].Standard;
    User.HadMultipleCandidates = HadMultipleCandidates;
    User.ConversionFunction = Conversion;
    User.FoundConversionFunction = Best->FoundDecl;
    User.EllipsisConversion = false;

    // C++ [over.ics.user]p2:
    //   The second standard conversion sequence converts the
    //   result of the user-defined conversion to the target type
    //   for the sequence. Since an implicit conversion sequence
    //   is an initialization, the special rules for
    //   initialization by user-defined conversion apply when
    //   selecting the best user-defined conversion for a
    //   user-defined conversion sequence (see 13.3.3 and
    //   13.3.3.1).
    User.After = Best->FinalConversion;
    return Result;
  }
  llvm_unreachable("Not a constructor or conversion function?")__builtin_unreachable();

case OR_No_Viable_Function:
  return OR_No_Viable_Function;

case OR_Ambiguous:
  return OR_Ambiguous;
}

llvm_unreachable("Invalid OverloadResult!")__builtin_unreachable();
3615}

3617bool
3618Sema::DiagnoseMultipleUserDefinedConversion(Expr *From, QualType ToType) {
ImplicitConversionSequence ICS;
OverloadCandidateSet CandidateSet(From->getExprLoc(),
                                  OverloadCandidateSet::CSK_Normal);
OverloadingResult OvResult =
  IsUserDefinedConversion(*this, From, ToType, ICS.UserDefined,
                          CandidateSet, AllowedExplicit::None, false);

if (!(OvResult == OR_Ambiguous ||
      (OvResult == OR_No_Viable_Function && !CandidateSet.empty())))
  return false;

auto Cands = CandidateSet.CompleteCandidates(
    *this,
    OvResult == OR_Ambiguous ? OCD_AmbiguousCandidates : OCD_AllCandidates,
    From);
if (OvResult == OR_Ambiguous)
  Diag(From->getBeginLoc(), diag::err_typecheck_ambiguous_condition)
      << From->getType() << ToType << From->getSourceRange();
else { // OR_No_Viable_Function && !CandidateSet.empty()
  if (!RequireCompleteType(From->getBeginLoc(), ToType,
                           diag::err_typecheck_nonviable_condition_incomplete,
                           From->getType(), From->getSourceRange()))
    Diag(From->getBeginLoc(), diag::err_typecheck_nonviable_condition)
        << false << From->getType() << From->getSourceRange() << ToType;
}

CandidateSet.NoteCandidates(
                            *this, From, Cands);
return true;
3648}

3650// Helper for compareConversionFunctions that gets the FunctionType that the
3651// conversion-operator return  value 'points' to, or nullptr.
3652static const FunctionType *
3653getConversionOpReturnTyAsFunction(CXXConversionDecl *Conv) {
const FunctionType *ConvFuncTy = Conv->getType()->castAs<FunctionType>();
const PointerType *RetPtrTy =
    ConvFuncTy->getReturnType()->getAs<PointerType>();

if (!RetPtrTy)
  return nullptr;

return RetPtrTy->getPointeeType()->getAs<FunctionType>();
3662}

3664/// Compare the user-defined conversion functions or constructors
3665/// of two user-defined conversion sequences to determine whether any ordering
3666/// is possible.
3667static ImplicitConversionSequence::CompareKind
3668compareConversionFunctions(Sema &S, FunctionDecl *Function1,
                         FunctionDecl *Function2) {
CXXConversionDecl *Conv1 = dyn_cast_or_null<CXXConversionDecl>(Function1);
CXXConversionDecl *Conv2 = dyn_cast_or_null<CXXConversionDecl>(Function2);
if (!Conv1 || !Conv2)
  return ImplicitConversionSequence::Indistinguishable;

if (!Conv1->getParent()->isLambda() || !Conv2->getParent()->isLambda())
  return ImplicitConversionSequence::Indistinguishable;

// Objective-C++:
//   If both conversion functions are implicitly-declared conversions from
//   a lambda closure type to a function pointer and a block pointer,
//   respectively, always prefer the conversion to a function pointer,
//   because the function pointer is more lightweight and is more likely
//   to keep code working.
if (S.getLangOpts().ObjC && S.getLangOpts().CPlusPlus11) {
  bool Block1 = Conv1->getConversionType()->isBlockPointerType();
  bool Block2 = Conv2->getConversionType()->isBlockPointerType();
  if (Block1 != Block2)
    return Block1 ? ImplicitConversionSequence::Worse
                  : ImplicitConversionSequence::Better;
}

// In order to support multiple calling conventions for the lambda conversion
// operator (such as when the free and member function calling convention is
// different), prefer the 'free' mechanism, followed by the calling-convention
// of operator(). The latter is in place to support the MSVC-like solution of
// defining ALL of the possible conversions in regards to calling-convention.
const FunctionType *Conv1FuncRet = getConversionOpReturnTyAsFunction(Conv1);
const FunctionType *Conv2FuncRet = getConversionOpReturnTyAsFunction(Conv2);

if (Conv1FuncRet && Conv2FuncRet &&
    Conv1FuncRet->getCallConv() != Conv2FuncRet->getCallConv()) {
  CallingConv Conv1CC = Conv1FuncRet->getCallConv();
  CallingConv Conv2CC = Conv2FuncRet->getCallConv();

  CXXMethodDecl *CallOp = Conv2->getParent()->getLambdaCallOperator();
  const FunctionProtoType *CallOpProto =
      CallOp->getType()->getAs<FunctionProtoType>();

  CallingConv CallOpCC =
      CallOp->getType()->castAs<FunctionType>()->getCallConv();
  CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
      CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
  CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
      CallOpProto->isVariadic(), /*IsCXXMethod=*/true);

  CallingConv PrefOrder[] = {DefaultFree, DefaultMember, CallOpCC};
  for (CallingConv CC : PrefOrder) {
    if (Conv1CC == CC)
      return ImplicitConversionSequence::Better;
    if (Conv2CC == CC)
      return ImplicitConversionSequence::Worse;
  }
}

return ImplicitConversionSequence::Indistinguishable;
3726}

3728static bool hasDeprecatedStringLiteralToCharPtrConversion(
  const ImplicitConversionSequence &ICS) {
return (ICS.isStandard() && ICS.Standard.DeprecatedStringLiteralToCharPtr) ||
       (ICS.isUserDefined() &&
        ICS.UserDefined.Before.DeprecatedStringLiteralToCharPtr);
3733}

3735/// CompareImplicitConversionSequences - Compare two implicit
3736/// conversion sequences to determine whether one is better than the
3737/// other or if they are indistinguishable (C++ 13.3.3.2).
3738static ImplicitConversionSequence::CompareKind
3739CompareImplicitConversionSequences(Sema &S, SourceLocation Loc,
                                 const ImplicitConversionSequence& ICS1,
                                 const ImplicitConversionSequence& ICS2)
3742{
// (C++ 13.3.3.2p2): When comparing the basic forms of implicit
// conversion sequences (as defined in 13.3.3.1)
//   -- a standard conversion sequence (13.3.3.1.1) is a better
//      conversion sequence than a user-defined conversion sequence or
//      an ellipsis conversion sequence, and
//   -- a user-defined conversion sequence (13.3.3.1.2) is a better
//      conversion sequence than an ellipsis conversion sequence
//      (13.3.3.1.3).
//
// C++0x [over.best.ics]p10:
//   For the purpose of ranking implicit conversion sequences as
//   described in 13.3.3.2, the ambiguous conversion sequence is
//   treated as a user-defined sequence that is indistinguishable
//   from any other user-defined conversion sequence.

// String literal to 'char *' conversion has been deprecated in C++03. It has
// been removed from C++11. We still accept this conversion, if it happens at
// the best viable function. Otherwise, this conversion is considered worse
// than ellipsis conversion. Consider this as an extension; this is not in the
// standard. For example:
//
// int &f(...);    // #1
// void f(char*);  // #2
// void g() { int &r = f("foo"); }
//
// In C++03, we pick #2 as the best viable function.
// In C++11, we pick #1 as the best viable function, because ellipsis
// conversion is better than string-literal to char* conversion (since there
// is no such conversion in C++11). If there was no #1 at all or #1 couldn't
// convert arguments, #2 would be the best viable function in C++11.
// If the best viable function has this conversion, a warning will be issued
// in C++03, or an ExtWarn (+SFINAE failure) will be issued in C++11.

if (S.getLangOpts().CPlusPlus11 && !S.getLangOpts().WritableStrings &&
    hasDeprecatedStringLiteralToCharPtrConversion(ICS1) !=
    hasDeprecatedStringLiteralToCharPtrConversion(ICS2))
  return hasDeprecatedStringLiteralToCharPtrConversion(ICS1)
             ? ImplicitConversionSequence::Worse
             : ImplicitConversionSequence::Better;

if (ICS1.getKindRank() < ICS2.getKindRank())
  return ImplicitConversionSequence::Better;
if (ICS2.getKindRank() < ICS1.getKindRank())
  return ImplicitConversionSequence::Worse;

// The following checks require both conversion sequences to be of
// the same kind.
if (ICS1.getKind() != ICS2.getKind())
  return ImplicitConversionSequence::Indistinguishable;

ImplicitConversionSequence::CompareKind Result =
    ImplicitConversionSequence::Indistinguishable;

// Two implicit conversion sequences of the same form are
// indistinguishable conversion sequences unless one of the
// following rules apply: (C++ 13.3.3.2p3):

// List-initialization sequence L1 is a better conversion sequence than
// list-initialization sequence L2 if:
// - L1 converts to std::initializer_list<X> for some X and L2 does not, or,
//   if not that,
// - L1 converts to type "array of N1 T", L2 converts to type "array of N2 T",
//   and N1 is smaller than N2.,
// even if one of the other rules in this paragraph would otherwise apply.
if (!ICS1.isBad()) {
  if (ICS1.isStdInitializerListElement() &&
      !ICS2.isStdInitializerListElement())
    return ImplicitConversionSequence::Better;
  if (!ICS1.isStdInitializerListElement() &&
      ICS2.isStdInitializerListElement())
    return ImplicitConversionSequence::Worse;
}

if (ICS1.isStandard())
  // Standard conversion sequence S1 is a better conversion sequence than
  // standard conversion sequence S2 if [...]
  Result = CompareStandardConversionSequences(S, Loc,
                                              ICS1.Standard, ICS2.Standard);
else if (ICS1.isUserDefined()) {
  // User-defined conversion sequence U1 is a better conversion
  // sequence than another user-defined conversion sequence U2 if
  // they contain the same user-defined conversion function or
  // constructor and if the second standard conversion sequence of
  // U1 is better than the second standard conversion sequence of
  // U2 (C++ 13.3.3.2p3).
  if (ICS1.UserDefined.ConversionFunction ==
        ICS2.UserDefined.ConversionFunction)
    Result = CompareStandardConversionSequences(S, Loc,
                                                ICS1.UserDefined.After,
                                                ICS2.UserDefined.After);
  else
    Result = compareConversionFunctions(S,
                                        ICS1.UserDefined.ConversionFunction,
                                        ICS2.UserDefined.ConversionFunction);
}

return Result;
3840}

3842// Per 13.3.3.2p3, compare the given standard conversion sequences to
3843// determine if one is a proper subset of the other.
3844static ImplicitConversionSequence::CompareKind
3845compareStandardConversionSubsets(ASTContext &Context,
                               const StandardConversionSequence& SCS1,
                               const StandardConversionSequence& SCS2) {
ImplicitConversionSequence::CompareKind Result
  = ImplicitConversionSequence::Indistinguishable;

// the identity conversion sequence is considered to be a subsequence of
// any non-identity conversion sequence
if (SCS1.isIdentityConversion() && !SCS2.isIdentityConversion())
  return ImplicitConversionSequence::Better;
else if (!SCS1.isIdentityConversion() && SCS2.isIdentityConversion())
  return ImplicitConversionSequence::Worse;

if (SCS1.Second != SCS2.Second) {
  if (SCS1.Second == ICK_Identity)
    Result = ImplicitConversionSequence::Better;
  else if (SCS2.Second == ICK_Identity)
    Result = ImplicitConversionSequence::Worse;
  else
    return ImplicitConversionSequence::Indistinguishable;
} else if (!Context.hasSimilarType(SCS1.getToType(1), SCS2.getToType(1)))
  return ImplicitConversionSequence::Indistinguishable;

if (SCS1.Third == SCS2.Third) {
  return Context.hasSameType(SCS1.getToType(2), SCS2.getToType(2))? Result
                           : ImplicitConversionSequence::Indistinguishable;
}

if (SCS1.Third == ICK_Identity)
  return Result == ImplicitConversionSequence::Worse
           ? ImplicitConversionSequence::Indistinguishable
           : ImplicitConversionSequence::Better;

if (SCS2.Third == ICK_Identity)
  return Result == ImplicitConversionSequence::Better
           ? ImplicitConversionSequence::Indistinguishable
           : ImplicitConversionSequence::Worse;

return ImplicitConversionSequence::Indistinguishable;
3884}

3886/// Determine whether one of the given reference bindings is better
3887/// than the other based on what kind of bindings they are.
3888static bool
3889isBetterReferenceBindingKind(const StandardConversionSequence &SCS1,
                           const StandardConversionSequence &SCS2) {
// C++0x [over.ics.rank]p3b4:
//   -- S1 and S2 are reference bindings (8.5.3) and neither refers to an
//      implicit object parameter of a non-static member function declared
//      without a ref-qualifier, and *either* S1 binds an rvalue reference
//      to an rvalue and S2 binds an lvalue reference *or S1 binds an
//      lvalue reference to a function lvalue and S2 binds an rvalue
//      reference*.
//
// FIXME: Rvalue references. We're going rogue with the above edits,
// because the semantics in the current C++0x working paper (N3225 at the
// time of this writing) break the standard definition of std::forward
// and std::reference_wrapper when dealing with references to functions.
// Proposed wording changes submitted to CWG for consideration.
if (SCS1.BindsImplicitObjectArgumentWithoutRefQualifier ||
    SCS2.BindsImplicitObjectArgumentWithoutRefQualifier)
  return false;

return (!SCS1.IsLvalueReference && SCS1.BindsToRvalue &&
        SCS2.IsLvalueReference) ||
       (SCS1.IsLvalueReference && SCS1.BindsToFunctionLvalue &&
        !SCS2.IsLvalueReference && SCS2.BindsToFunctionLvalue);
3912}

3914enum class FixedEnumPromotion {
None,
ToUnderlyingType,
ToPromotedUnderlyingType
3918};

3920/// Returns kind of fixed enum promotion the \a SCS uses.
3921static FixedEnumPromotion
3922getFixedEnumPromtion(Sema &S, const StandardConversionSequence &SCS) {

if (SCS.Second != ICK_Integral_Promotion)
  return FixedEnumPromotion::None;

QualType FromType = SCS.getFromType();
if (!FromType->isEnumeralType())
  return FixedEnumPromotion::None;

EnumDecl *Enum = FromType->castAs<EnumType>()->getDecl();
if (!Enum->isFixed())
  return FixedEnumPromotion::None;

QualType UnderlyingType = Enum->getIntegerType();
if (S.Context.hasSameType(SCS.getToType(1), UnderlyingType))
  return FixedEnumPromotion::ToUnderlyingType;

return FixedEnumPromotion::ToPromotedUnderlyingType;
3940}

3942/// CompareStandardConversionSequences - Compare two standard
3943/// conversion sequences to determine whether one is better than the
3944/// other or if they are indistinguishable (C++ 13.3.3.2p3).
3945static ImplicitConversionSequence::CompareKind
3946CompareStandardConversionSequences(Sema &S, SourceLocation Loc,
                                 const StandardConversionSequence& SCS1,
                                 const StandardConversionSequence& SCS2)
3949{
// Standard conversion sequence S1 is a better conversion sequence
// than standard conversion sequence S2 if (C++ 13.3.3.2p3):

//  -- S1 is a proper subsequence of S2 (comparing the conversion
//     sequences in the canonical form defined by 13.3.3.1.1,
//     excluding any Lvalue Transformation; the identity conversion
//     sequence is considered to be a subsequence of any
//     non-identity conversion sequence) or, if not that,
if (ImplicitConversionSequence::CompareKind CK
      = compareStandardConversionSubsets(S.Context, SCS1, SCS2))
  return CK;

//  -- the rank of S1 is better than the rank of S2 (by the rules
//     defined below), or, if not that,
ImplicitConversionRank Rank1 = SCS1.getRank();
ImplicitConversionRank Rank2 = SCS2.getRank();
if (Rank1 < Rank2)
  return ImplicitConversionSequence::Better;
else if (Rank2 < Rank1)
  return ImplicitConversionSequence::Worse;

// (C++ 13.3.3.2p4): Two conversion sequences with the same rank
// are indistinguishable unless one of the following rules
// applies:

//   A conversion that is not a conversion of a pointer, or
//   pointer to member, to bool is better than another conversion
//   that is such a conversion.
if (SCS1.isPointerConversionToBool() != SCS2.isPointerConversionToBool())
  return SCS2.isPointerConversionToBool()
           ? ImplicitConversionSequence::Better
           : ImplicitConversionSequence::Worse;

// C++14 [over.ics.rank]p4b2:
// This is retroactively applied to C++11 by CWG 1601.
//
//   A conversion that promotes an enumeration whose underlying type is fixed
//   to its underlying type is better than one that promotes to the promoted
//   underlying type, if the two are different.
FixedEnumPromotion FEP1 = getFixedEnumPromtion(S, SCS1);
FixedEnumPromotion FEP2 = getFixedEnumPromtion(S, SCS2);
if (FEP1 != FixedEnumPromotion::None && FEP2 != FixedEnumPromotion::None &&
    FEP1 != FEP2)
  return FEP1 == FixedEnumPromotion::ToUnderlyingType
             ? ImplicitConversionSequence::Better
             : ImplicitConversionSequence::Worse;

// C++ [over.ics.rank]p4b2:
//
//   If class B is derived directly or indirectly from class A,
//   conversion of B* to A* is better than conversion of B* to
//   void*, and conversion of A* to void* is better than conversion
//   of B* to void*.
bool SCS1ConvertsToVoid
  = SCS1.isPointerConversionToVoidPointer(S.Context);
bool SCS2ConvertsToVoid
  = SCS2.isPointerConversionToVoidPointer(S.Context);
if (SCS1ConvertsToVoid != SCS2ConvertsToVoid) {
  // Exactly one of the conversion sequences is a conversion to
  // a void pointer; it's the worse conversion.
  return SCS2ConvertsToVoid ? ImplicitConversionSequence::Better
                            : ImplicitConversionSequence::Worse;
} else if (!SCS1ConvertsToVoid && !SCS2ConvertsToVoid) {
  // Neither conversion sequence converts to a void pointer; compare
  // their derived-to-base conversions.
  if (ImplicitConversionSequence::CompareKind DerivedCK
        = CompareDerivedToBaseConversions(S, Loc, SCS1, SCS2))
    return DerivedCK;
} else if (SCS1ConvertsToVoid && SCS2ConvertsToVoid &&
           !S.Context.hasSameType(SCS1.getFromType(), SCS2.getFromType())) {
  // Both conversion sequences are conversions to void
  // pointers. Compare the source types to determine if there's an
  // inheritance relationship in their sources.
  QualType FromType1 = SCS1.getFromType();
  QualType FromType2 = SCS2.getFromType();

  // Adjust the types we're converting from via the array-to-pointer
  // conversion, if we need to.
  if (SCS1.First == ICK_Array_To_Pointer)
    FromType1 = S.Context.getArrayDecayedType(FromType1);
  if (SCS2.First == ICK_Array_To_Pointer)
    FromType2 = S.Context.getArrayDecayedType(FromType2);

  QualType FromPointee1 = FromType1->getPointeeType().getUnqualifiedType();
  QualType FromPointee2 = FromType2->getPointeeType().getUnqualifiedType();

  if (S.IsDerivedFrom(Loc, FromPointee2, FromPointee1))
    return ImplicitConversionSequence::Better;
  else if (S.IsDerivedFrom(Loc, FromPointee1, FromPointee2))
    return ImplicitConversionSequence::Worse;

  // Objective-C++: If one interface is more specific than the
  // other, it is the better one.
  const ObjCObjectPointerType* FromObjCPtr1
    = FromType1->getAs<ObjCObjectPointerType>();
  const ObjCObjectPointerType* FromObjCPtr2
    = FromType2->getAs<ObjCObjectPointerType>();
  if (FromObjCPtr1 && FromObjCPtr2) {
    bool AssignLeft = S.Context.canAssignObjCInterfaces(FromObjCPtr1,
                                                        FromObjCPtr2);
    bool AssignRight = S.Context.canAssignObjCInterfaces(FromObjCPtr2,
                                                         FromObjCPtr1);
    if (AssignLeft != AssignRight) {
      return AssignLeft? ImplicitConversionSequence::Better
                       : ImplicitConversionSequence::Worse;
    }
  }
}

if (SCS1.ReferenceBinding && SCS2.ReferenceBinding) {
  // Check for a better reference binding based on the kind of bindings.
  if (isBetterReferenceBindingKind(SCS1, SCS2))
    return ImplicitConversionSequence::Better;
  else if (isBetterReferenceBindingKind(SCS2, SCS1))
    return ImplicitConversionSequence::Worse;
}

// Compare based on qualification conversions (C++ 13.3.3.2p3,
// bullet 3).
if (ImplicitConversionSequence::CompareKind QualCK
      = CompareQualificationConversions(S, SCS1, SCS2))
  return QualCK;

if (SCS1.ReferenceBinding && SCS2.ReferenceBinding) {
  // C++ [over.ics.rank]p3b4:
  //   -- S1 and S2 are reference bindings (8.5.3), and the types to
  //      which the references refer are the same type except for
  //      top-level cv-qualifiers, and the type to which the reference
  //      initialized by S2 refers is more cv-qualified than the type
  //      to which the reference initialized by S1 refers.
  QualType T1 = SCS1.getToType(2);
  QualType T2 = SCS2.getToType(2);
  T1 = S.Context.getCanonicalType(T1);
  T2 = S.Context.getCanonicalType(T2);
  Qualifiers T1Quals, T2Quals;
  QualType UnqualT1 = S.Context.getUnqualifiedArrayType(T1, T1Quals);
  QualType UnqualT2 = S.Context.getUnqualifiedArrayType(T2, T2Quals);
  if (UnqualT1 == UnqualT2) {
    // Objective-C++ ARC: If the references refer to objects with different
    // lifetimes, prefer bindings that don't change lifetime.
    if (SCS1.ObjCLifetimeConversionBinding !=
                                        SCS2.ObjCLifetimeConversionBinding) {
      return SCS1.ObjCLifetimeConversionBinding
                                         ? ImplicitConversionSequence::Worse
                                         : ImplicitConversionSequence::Better;
    }

    // If the type is an array type, promote the element qualifiers to the
    // type for comparison.
    if (isa<ArrayType>(T1) && T1Quals)
      T1 = S.Context.getQualifiedType(UnqualT1, T1Quals);
    if (isa<ArrayType>(T2) && T2Quals)
      T2 = S.Context.getQualifiedType(UnqualT2, T2Quals);
    if (T2.isMoreQualifiedThan(T1))
      return ImplicitConversionSequence::Better;
    if (T1.isMoreQualifiedThan(T2))
      return ImplicitConversionSequence::Worse;
  }
}

// In Microsoft mode (below 19.28), prefer an integral conversion to a
// floating-to-integral conversion if the integral conversion
// is between types of the same size.
// For example:
// void f(float);
// void f(int);
// int main {
//    long a;
//    f(a);
// }
// Here, MSVC will call f(int) instead of generating a compile error
// as clang will do in standard mode.
if (S.getLangOpts().MSVCCompat &&
    !S.getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2019_8) &&
    SCS1.Second == ICK_Integral_Conversion &&
    SCS2.Second == ICK_Floating_Integral &&
    S.Context.getTypeSize(SCS1.getFromType()) ==
        S.Context.getTypeSize(SCS1.getToType(2)))
  return ImplicitConversionSequence::Better;

// Prefer a compatible vector conversion over a lax vector conversion
// For example:
//
// typedef float __v4sf __attribute__((__vector_size__(16)));
// void f(vector float);
// void f(vector signed int);
// int main() {
//   __v4sf a;
//   f(a);
// }
// Here, we'd like to choose f(vector float) and not
// report an ambiguous call error
if (SCS1.Second == ICK_Vector_Conversion &&
    SCS2.Second == ICK_Vector_Conversion) {
  bool SCS1IsCompatibleVectorConversion = S.Context.areCompatibleVectorTypes(
      SCS1.getFromType(), SCS1.getToType(2));
  bool SCS2IsCompatibleVectorConversion = S.Context.areCompatibleVectorTypes(
      SCS2.getFromType(), SCS2.getToType(2));

  if (SCS1IsCompatibleVectorConversion != SCS2IsCompatibleVectorConversion)
    return SCS1IsCompatibleVectorConversion
               ? ImplicitConversionSequence::Better
               : ImplicitConversionSequence::Worse;
}

if (SCS1.Second == ICK_SVE_Vector_Conversion &&
    SCS2.Second == ICK_SVE_Vector_Conversion) {
  bool SCS1IsCompatibleSVEVectorConversion =
      S.Context.areCompatibleSveTypes(SCS1.getFromType(), SCS1.getToType(2));
  bool SCS2IsCompatibleSVEVectorConversion =
      S.Context.areCompatibleSveTypes(SCS2.getFromType(), SCS2.getToType(2));

  if (SCS1IsCompatibleSVEVectorConversion !=
      SCS2IsCompatibleSVEVectorConversion)
    return SCS1IsCompatibleSVEVectorConversion
               ? ImplicitConversionSequence::Better
               : ImplicitConversionSequence::Worse;
}

return ImplicitConversionSequence::Indistinguishable;
4170}

4172/// CompareQualificationConversions - Compares two standard conversion
4173/// sequences to determine whether they can be ranked based on their
4174/// qualification conversions (C++ 13.3.3.2p3 bullet 3).
4175static ImplicitConversionSequence::CompareKind
4176CompareQualificationConversions(Sema &S,
                              const StandardConversionSequence& SCS1,
                              const StandardConversionSequence& SCS2) {
// C++ 13.3.3.2p3:
//  -- S1 and S2 differ only in their qualification conversion and
//     yield similar types T1 and T2 (C++ 4.4), respectively, and the
//     cv-qualification signature of type T1 is a proper subset of
//     the cv-qualification signature of type T2, and S1 is not the
//     deprecated string literal array-to-pointer conversion (4.2).
if (SCS1.First != SCS2.First || SCS1.Second != SCS2.Second ||
    SCS1.Third != SCS2.Third || SCS1.Third != ICK_Qualification)
  return ImplicitConversionSequence::Indistinguishable;

// FIXME: the example in the standard doesn't use a qualification
// conversion (!)
QualType T1 = SCS1.getToType(2);
QualType T2 = SCS2.getToType(2);
T1 = S.Context.getCanonicalType(T1);
T2 = S.Context.getCanonicalType(T2);
assert(!T1->isReferenceType() && !T2->isReferenceType())((void)0);
Qualifiers T1Quals, T2Quals;
QualType UnqualT1 = S.Context.getUnqualifiedArrayType(T1, T1Quals);
QualType UnqualT2 = S.Context.getUnqualifiedArrayType(T2, T2Quals);

// If the types are the same, we won't learn anything by unwrapping
// them.
if (UnqualT1 == UnqualT2)
  return ImplicitConversionSequence::Indistinguishable;

ImplicitConversionSequence::CompareKind Result
  = ImplicitConversionSequence::Indistinguishable;

// Objective-C++ ARC:
//   Prefer qualification conversions not involving a change in lifetime
//   to qualification conversions that do not change lifetime.
if (SCS1.QualificationIncludesObjCLifetime !=
                                    SCS2.QualificationIncludesObjCLifetime) {
  Result = SCS1.QualificationIncludesObjCLifetime
             ? ImplicitConversionSequence::Worse
             : ImplicitConversionSequence::Better;
}

while (S.Context.UnwrapSimilarTypes(T1, T2)) {
  // Within each iteration of the loop, we check the qualifiers to
  // determine if this still looks like a qualification
  // conversion. Then, if all is well, we unwrap one more level of
  // pointers or pointers-to-members and do it all again
  // until there are no more pointers or pointers-to-members left
  // to unwrap. This essentially mimics what
  // IsQualificationConversion does, but here we're checking for a
  // strict subset of qualifiers.
  if (T1.getQualifiers().withoutObjCLifetime() ==
      T2.getQualifiers().withoutObjCLifetime())
    // The qualifiers are the same, so this doesn't tell us anything
    // about how the sequences rank.
    // ObjC ownership quals are omitted above as they interfere with
    // the ARC overload rule.
    ;
  else if (T2.isMoreQualifiedThan(T1)) {
    // T1 has fewer qualifiers, so it could be the better sequence.
    if (Result == ImplicitConversionSequence::Worse)
      // Neither has qualifiers that are a subset of the other's
      // qualifiers.
      return ImplicitConversionSequence::Indistinguishable;

    Result = ImplicitConversionSequence::Better;
  } else if (T1.isMoreQualifiedThan(T2)) {
    // T2 has fewer qualifiers, so it could be the better sequence.
    if (Result == ImplicitConversionSequence::Better)
      // Neither has qualifiers that are a subset of the other's
      // qualifiers.
      return ImplicitConversionSequence::Indistinguishable;

    Result = ImplicitConversionSequence::Worse;
  } else {
    // Qualifiers are disjoint.
    return ImplicitConversionSequence::Indistinguishable;
  }

  // If the types after this point are equivalent, we're done.
  if (S.Context.hasSameUnqualifiedType(T1, T2))
    break;
}

// Check that the winning standard conversion sequence isn't using
// the deprecated string literal array to pointer conversion.
switch (Result) {
case ImplicitConversionSequence::Better:
  if (SCS1.DeprecatedStringLiteralToCharPtr)
    Result = ImplicitConversionSequence::Indistinguishable;
  break;

case ImplicitConversionSequence::Indistinguishable:
  break;

case ImplicitConversionSequence::Worse:
  if (SCS2.DeprecatedStringLiteralToCharPtr)
    Result = ImplicitConversionSequence::Indistinguishable;
  break;
}

return Result;
4278}

4280/// CompareDerivedToBaseConversions - Compares two standard conversion
4281/// sequences to determine whether they can be ranked based on their
4282/// various kinds of derived-to-base conversions (C++
4283/// [over.ics.rank]p4b3).  As part of these checks, we also look at
4284/// conversions between Objective-C interface types.
4285static ImplicitConversionSequence::CompareKind
4286CompareDerivedToBaseConversions(Sema &S, SourceLocation Loc,
                              const StandardConversionSequence& SCS1,
                              const StandardConversionSequence& SCS2) {
QualType FromType1 = SCS1.getFromType();
QualType ToType1 = SCS1.getToType(1);
QualType FromType2 = SCS2.getFromType();
QualType ToType2 = SCS2.getToType(1);

// Adjust the types we're converting from via the array-to-pointer
// conversion, if we need to.
if (SCS1.First == ICK_Array_To_Pointer)
  FromType1 = S.Context.getArrayDecayedType(FromType1);
if (SCS2.First == ICK_Array_To_Pointer)
  FromType2 = S.Context.getArrayDecayedType(FromType2);

// Canonicalize all of the types.
FromType1 = S.Context.getCanonicalType(FromType1);
ToType1 = S.Context.getCanonicalType(ToType1);
FromType2 = S.Context.getCanonicalType(FromType2);
ToType2 = S.Context.getCanonicalType(ToType2);

// C++ [over.ics.rank]p4b3:
//
//   If class B is derived directly or indirectly from class A and
//   class C is derived directly or indirectly from B,
//
// Compare based on pointer conversions.
if (SCS1.Second == ICK_Pointer_Conversion &&
    SCS2.Second == ICK_Pointer_Conversion &&
    /*FIXME: Remove if Objective-C id conversions get their own rank*/
    FromType1->isPointerType() && FromType2->isPointerType() &&
    ToType1->isPointerType() && ToType2->isPointerType()) {
  QualType FromPointee1 =
      FromType1->castAs<PointerType>()->getPointeeType().getUnqualifiedType();
  QualType ToPointee1 =
      ToType1->castAs<PointerType>()->getPointeeType().getUnqualifiedType();
  QualType FromPointee2 =
      FromType2->castAs<PointerType>()->getPointeeType().getUnqualifiedType();
  QualType ToPointee2 =
      ToType2->castAs<PointerType>()->getPointeeType().getUnqualifiedType();

  //   -- conversion of C* to B* is better than conversion of C* to A*,
  if (FromPointee1 == FromPointee2 && ToPointee1 != ToPointee2) {
    if (S.IsDerivedFrom(Loc, ToPointee1, ToPointee2))
      return ImplicitConversionSequence::Better;
    else if (S.IsDerivedFrom(Loc, ToPointee2, ToPointee1))
      return ImplicitConversionSequence::Worse;
  }

  //   -- conversion of B* to A* is better than conversion of C* to A*,
  if (FromPointee1 != FromPointee2 && ToPointee1 == ToPointee2) {
    if (S.IsDerivedFrom(Loc, FromPointee2, FromPointee1))
      return ImplicitConversionSequence::Better;
    else if (S.IsDerivedFrom(Loc, FromPointee1, FromPointee2))
      return ImplicitConversionSequence::Worse;
  }
} else if (SCS1.Second == ICK_Pointer_Conversion &&
           SCS2.Second == ICK_Pointer_Conversion) {
  const ObjCObjectPointerType *FromPtr1
    = FromType1->getAs<ObjCObjectPointerType>();
  const ObjCObjectPointerType *FromPtr2
    = FromType2->getAs<ObjCObjectPointerType>();
  const ObjCObjectPointerType *ToPtr1
    = ToType1->getAs<ObjCObjectPointerType>();
  const ObjCObjectPointerType *ToPtr2
    = ToType2->getAs<ObjCObjectPointerType>();

  if (FromPtr1 && FromPtr2 && ToPtr1 && ToPtr2) {
    // Apply the same conversion ranking rules for Objective-C pointer types
    // that we do for C++ pointers to class types. However, we employ the
    // Objective-C pseudo-subtyping relationship used for assignment of
    // Objective-C pointer types.
    bool FromAssignLeft
      = S.Context.canAssignObjCInterfaces(FromPtr1, FromPtr2);
    bool FromAssignRight
      = S.Context.canAssignObjCInterfaces(FromPtr2, FromPtr1);
    bool ToAssignLeft
      = S.Context.canAssignObjCInterfaces(ToPtr1, ToPtr2);
    bool ToAssignRight
      = S.Context.canAssignObjCInterfaces(ToPtr2, ToPtr1);

    // A conversion to an a non-id object pointer type or qualified 'id'
    // type is better than a conversion to 'id'.
    if (ToPtr1->isObjCIdType() &&
        (ToPtr2->isObjCQualifiedIdType() || ToPtr2->getInterfaceDecl()))
      return ImplicitConversionSequence::Worse;
    if (ToPtr2->isObjCIdType() &&
        (ToPtr1->isObjCQualifiedIdType() || ToPtr1->getInterfaceDecl()))
      return ImplicitConversionSequence::Better;

    // A conversion to a non-id object pointer type is better than a
    // conversion to a qualified 'id' type
    if (ToPtr1->isObjCQualifiedIdType() && ToPtr2->getInterfaceDecl())
      return ImplicitConversionSequence::Worse;
    if (ToPtr2->isObjCQualifiedIdType() && ToPtr1->getInterfaceDecl())
      return ImplicitConversionSequence::Better;

    // A conversion to an a non-Class object pointer type or qualified 'Class'
    // type is better than a conversion to 'Class'.
    if (ToPtr1->isObjCClassType() &&
        (ToPtr2->isObjCQualifiedClassType() || ToPtr2->getInterfaceDecl()))
      return ImplicitConversionSequence::Worse;
    if (ToPtr2->isObjCClassType() &&
        (ToPtr1->isObjCQualifiedClassType() || ToPtr1->getInterfaceDecl()))
      return ImplicitConversionSequence::Better;

    // A conversion to a non-Class object pointer type is better than a
    // conversion to a qualified 'Class' type.
    if (ToPtr1->isObjCQualifiedClassType() && ToPtr2->getInterfaceDecl())
      return ImplicitConversionSequence::Worse;
    if (ToPtr2->isObjCQualifiedClassType() && ToPtr1->getInterfaceDecl())
      return ImplicitConversionSequence::Better;

    //   -- "conversion of C* to B* is better than conversion of C* to A*,"
    if (S.Context.hasSameType(FromType1, FromType2) &&
        !FromPtr1->isObjCIdType() && !FromPtr1->isObjCClassType() &&
        (ToAssignLeft != ToAssignRight)) {
      if (FromPtr1->isSpecialized()) {
        // "conversion of B<A> * to B * is better than conversion of B * to
        // C *.
        bool IsFirstSame =
            FromPtr1->getInterfaceDecl() == ToPtr1->getInterfaceDecl();
        bool IsSecondSame =
            FromPtr1->getInterfaceDecl() == ToPtr2->getInterfaceDecl();
        if (IsFirstSame) {
          if (!IsSecondSame)
            return ImplicitConversionSequence::Better;
        } else if (IsSecondSame)
          return ImplicitConversionSequence::Worse;
      }
      return ToAssignLeft? ImplicitConversionSequence::Worse
                         : ImplicitConversionSequence::Better;
    }

    //   -- "conversion of B* to A* is better than conversion of C* to A*,"
    if (S.Context.hasSameUnqualifiedType(ToType1, ToType2) &&
        (FromAssignLeft != FromAssignRight))
      return FromAssignLeft? ImplicitConversionSequence::Better
      : ImplicitConversionSequence::Worse;
  }
}

// Ranking of member-pointer types.
if (SCS1.Second == ICK_Pointer_Member && SCS2.Second == ICK_Pointer_Member &&
    FromType1->isMemberPointerType() && FromType2->isMemberPointerType() &&
    ToType1->isMemberPointerType() && ToType2->isMemberPointerType()) {
  const auto *FromMemPointer1 = FromType1->castAs<MemberPointerType>();
  const auto *ToMemPointer1 = ToType1->castAs<MemberPointerType>();
  const auto *FromMemPointer2 = FromType2->castAs<MemberPointerType>();
  const auto *ToMemPointer2 = ToType2->castAs<MemberPointerType>();
  const Type *FromPointeeType1 = FromMemPointer1->getClass();
  const Type *ToPointeeType1 = ToMemPointer1->getClass();
  const Type *FromPointeeType2 = FromMemPointer2->getClass();
  const Type *ToPointeeType2 = ToMemPointer2->getClass();
  QualType FromPointee1 = QualType(FromPointeeType1, 0).getUnqualifiedType();
  QualType ToPointee1 = QualType(ToPointeeType1, 0).getUnqualifiedType();
  QualType FromPointee2 = QualType(FromPointeeType2, 0).getUnqualifiedType();
  QualType ToPointee2 = QualType(ToPointeeType2, 0).getUnqualifiedType();
  // conversion of A::* to B::* is better than conversion of A::* to C::*,
  if (FromPointee1 == FromPointee2 && ToPointee1 != ToPointee2) {
    if (S.IsDerivedFrom(Loc, ToPointee1, ToPointee2))
      return ImplicitConversionSequence::Worse;
    else if (S.IsDerivedFrom(Loc, ToPointee2, ToPointee1))
      return ImplicitConversionSequence::Better;
  }
  // conversion of B::* to C::* is better than conversion of A::* to C::*
  if (ToPointee1 == ToPointee2 && FromPointee1 != FromPointee2) {
    if (S.IsDerivedFrom(Loc, FromPointee1, FromPointee2))
      return ImplicitConversionSequence::Better;
    else if (S.IsDerivedFrom(Loc, FromPointee2, FromPointee1))
      return ImplicitConversionSequence::Worse;
  }
}

if (SCS1.Second == ICK_Derived_To_Base) {
  //   -- conversion of C to B is better than conversion of C to A,
  //   -- binding of an expression of type C to a reference of type
  //      B& is better than binding an expression of type C to a
  //      reference of type A&,
  if (S.Context.hasSameUnqualifiedType(FromType1, FromType2) &&
      !S.Context.hasSameUnqualifiedType(ToType1, ToType2)) {
    if (S.IsDerivedFrom(Loc, ToType1, ToType2))
      return ImplicitConversionSequence::Better;
    else if (S.IsDerivedFrom(Loc, ToType2, ToType1))
      return ImplicitConversionSequence::Worse;
  }

  //   -- conversion of B to A is better than conversion of C to A.
  //   -- binding of an expression of type B to a reference of type
  //      A& is better than binding an expression of type C to a
  //      reference of type A&,
  if (!S.Context.hasSameUnqualifiedType(FromType1, FromType2) &&
      S.Context.hasSameUnqualifiedType(ToType1, ToType2)) {
    if (S.IsDerivedFrom(Loc, FromType2, FromType1))
      return ImplicitConversionSequence::Better;
    else if (S.IsDerivedFrom(Loc, FromType1, FromType2))
      return ImplicitConversionSequence::Worse;
  }
}

return ImplicitConversionSequence::Indistinguishable;
4487}

4489/// Determine whether the given type is valid, e.g., it is not an invalid
4490/// C++ class.
4491static bool isTypeValid(QualType T) {
if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
  return !Record->isInvalidDecl();

return true;
4496}

4498static QualType withoutUnaligned(ASTContext &Ctx, QualType T) {
if (!T.getQualifiers().hasUnaligned())
  return T;

Qualifiers Q;
T = Ctx.getUnqualifiedArrayType(T, Q);
Q.removeUnaligned();
return Ctx.getQualifiedType(T, Q);
4506}

4508/// CompareReferenceRelationship - Compare the two types T1 and T2 to
4509/// determine whether they are reference-compatible,
4510/// reference-related, or incompatible, for use in C++ initialization by
4511/// reference (C++ [dcl.ref.init]p4). Neither type can be a reference
4512/// type, and the first type (T1) is the pointee type of the reference
4513/// type being initialized.
4514Sema::ReferenceCompareResult
4515Sema::CompareReferenceRelationship(SourceLocation Loc,
                                 QualType OrigT1, QualType OrigT2,
                                 ReferenceConversions *ConvOut) {
assert(!OrigT1->isReferenceType() &&((void)0)
  "T1 must be the pointee type of the reference type")((void)0);
assert(!OrigT2->isReferenceType() && "T2 cannot be a reference type")((void)0);

QualType T1 = Context.getCanonicalType(OrigT1);
QualType T2 = Context.getCanonicalType(OrigT2);
Qualifiers T1Quals, T2Quals;
QualType UnqualT1 = Context.getUnqualifiedArrayType(T1, T1Quals);
QualType UnqualT2 = Context.getUnqualifiedArrayType(T2, T2Quals);

ReferenceConversions ConvTmp;
ReferenceConversions &Conv = ConvOut ? *ConvOut : ConvTmp;
Conv = ReferenceConversions();

// C++2a [dcl.init.ref]p4:
//   Given types "cv1 T1" and "cv2 T2," "cv1 T1" is
//   reference-related to "cv2 T2" if T1 is similar to T2, or
//   T1 is a base class of T2.
//   "cv1 T1" is reference-compatible with "cv2 T2" if
//   a prvalue of type "pointer to cv2 T2" can be converted to the type
//   "pointer to cv1 T1" via a standard conversion sequence.

// Check for standard conversions we can apply to pointers: derived-to-base
// conversions, ObjC pointer conversions, and function pointer conversions.
// (Qualification conversions are checked last.)
QualType ConvertedT2;
if (UnqualT1 == UnqualT2) {
  // Nothing to do.
} else if (isCompleteType(Loc, OrigT2) &&
           isTypeValid(UnqualT1) && isTypeValid(UnqualT2) &&
           IsDerivedFrom(Loc, UnqualT2, UnqualT1))
  Conv |= ReferenceConversions::DerivedToBase;
else if (UnqualT1->isObjCObjectOrInterfaceType() &&
         UnqualT2->isObjCObjectOrInterfaceType() &&
         Context.canBindObjCObjectType(UnqualT1, UnqualT2))
  Conv |= ReferenceConversions::ObjC;
else if (UnqualT2->isFunctionType() &&
         IsFunctionConversion(UnqualT2, UnqualT1, ConvertedT2)) {
  Conv |= ReferenceConversions::Function;
  // No need to check qualifiers; function types don't have them.
  return Ref_Compatible;
}
bool ConvertedReferent = Conv != 0;

// We can have a qualification conversion. Compute whether the types are
// similar at the same time.
bool PreviousToQualsIncludeConst = true;
bool TopLevel = true;
do {
  if (T1 == T2)
    break;

  // We will need a qualification conversion.
  Conv |= ReferenceConversions::Qualification;

  // Track whether we performed a qualification conversion anywhere other
  // than the top level. This matters for ranking reference bindings in
  // overload resolution.
  if (!TopLevel)
    Conv |= ReferenceConversions::NestedQualification;

  // MS compiler ignores __unaligned qualifier for references; do the same.
  T1 = withoutUnaligned(Context, T1);
  T2 = withoutUnaligned(Context, T2);

  // If we find a qualifier mismatch, the types are not reference-compatible,
  // but are still be reference-related if they're similar.
  bool ObjCLifetimeConversion = false;
  if (!isQualificationConversionStep(T2, T1, /*CStyle=*/false, TopLevel,
                                     PreviousToQualsIncludeConst,
                                     ObjCLifetimeConversion))
    return (ConvertedReferent || Context.hasSimilarType(T1, T2))
               ? Ref_Related
               : Ref_Incompatible;

  // FIXME: Should we track this for any level other than the first?
  if (ObjCLifetimeConversion)
    Conv |= ReferenceConversions::ObjCLifetime;

  TopLevel = false;
} while (Context.UnwrapSimilarTypes(T1, T2));

// At this point, if the types are reference-related, we must either have the
// same inner type (ignoring qualifiers), or must have already worked out how
// to convert the referent.
return (ConvertedReferent || Context.hasSameUnqualifiedType(T1, T2))
           ? Ref_Compatible
           : Ref_Incompatible;
4606}

4608/// Look for a user-defined conversion to a value reference-compatible
4609///        with DeclType. Return true if something definite is found.
4610static bool
4611FindConversionForRefInit(Sema &S, ImplicitConversionSequence &ICS,
                       QualType DeclType, SourceLocation DeclLoc,
                       Expr *Init, QualType T2, bool AllowRvalues,
                       bool AllowExplicit) {
assert(T2->isRecordType() && "Can only find conversions of record types.")((void)0);
auto *T2RecordDecl = cast<CXXRecordDecl>(T2->castAs<RecordType>()->getDecl());

OverloadCandidateSet CandidateSet(
    DeclLoc, OverloadCandidateSet::CSK_InitByUserDefinedConversion);
const auto &Conversions = T2RecordDecl->getVisibleConversionFunctions();
for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
  NamedDecl *D = *I;
  CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
  if (isa<UsingShadowDecl>(D))
    D = cast<UsingShadowDecl>(D)->getTargetDecl();

  FunctionTemplateDecl *ConvTemplate
    = dyn_cast<FunctionTemplateDecl>(D);
  CXXConversionDecl *Conv;
  if (ConvTemplate)
    Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
  else
    Conv = cast<CXXConversionDecl>(D);

  if (AllowRvalues) {
    // If we are initializing an rvalue reference, don't permit conversion
    // functions that return lvalues.
    if (!ConvTemplate && DeclType->isRValueReferenceType()) {
      const ReferenceType *RefType
        = Conv->getConversionType()->getAs<LValueReferenceType>();
      if (RefType && !RefType->getPointeeType()->isFunctionType())
        continue;
    }

    if (!ConvTemplate &&
        S.CompareReferenceRelationship(
            DeclLoc,
            Conv->getConversionType()
                .getNonReferenceType()
                .getUnqualifiedType(),
            DeclType.getNonReferenceType().getUnqualifiedType()) ==
            Sema::Ref_Incompatible)
      continue;
  } else {
    // If the conversion function doesn't return a reference type,
    // it can't be considered for this conversion. An rvalue reference
    // is only acceptable if its referencee is a function type.

    const ReferenceType *RefType =
      Conv->getConversionType()->getAs<ReferenceType>();
    if (!RefType ||
        (!RefType->isLValueReferenceType() &&
         !RefType->getPointeeType()->isFunctionType()))
      continue;
  }

  if (ConvTemplate)
    S.AddTemplateConversionCandidate(
        ConvTemplate, I.getPair(), ActingDC, Init, DeclType, CandidateSet,
        /*AllowObjCConversionOnExplicit=*/false, AllowExplicit);
  else
    S.AddConversionCandidate(
        Conv, I.getPair(), ActingDC, Init, DeclType, CandidateSet,
        /*AllowObjCConversionOnExplicit=*/false, AllowExplicit);
}

bool HadMultipleCandidates = (CandidateSet.size() > 1);

OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(S, DeclLoc, Best)) {
case OR_Success:
  // C++ [over.ics.ref]p1:
  //
  //   [...] If the parameter binds directly to the result of
  //   applying a conversion function to the argument
  //   expression, the implicit conversion sequence is a
  //   user-defined conversion sequence (13.3.3.1.2), with the
  //   second standard conversion sequence either an identity
  //   conversion or, if the conversion function returns an
  //   entity of a type that is a derived class of the parameter
  //   type, a derived-to-base Conversion.
  if (!Best->FinalConversion.DirectBinding)
    return false;

  ICS.setUserDefined();
  ICS.UserDefined.Before = Best->Conversions[0].Standard;
  ICS.UserDefined.After = Best->FinalConversion;
  ICS.UserDefined.HadMultipleCandidates = HadMultipleCandidates;
  ICS.UserDefined.ConversionFunction = Best->Function;
  ICS.UserDefined.FoundConversionFunction = Best->FoundDecl;
  ICS.UserDefined.EllipsisConversion = false;
  assert(ICS.UserDefined.After.ReferenceBinding &&((void)0)
         ICS.UserDefined.After.DirectBinding &&((void)0)
         "Expected a direct reference binding!")((void)0);
  return true;

case OR_Ambiguous:
  ICS.setAmbiguous();
  for (OverloadCandidateSet::iterator Cand = CandidateSet.begin();
       Cand != CandidateSet.end(); ++Cand)
    if (Cand->Best)
      ICS.Ambiguous.addConversion(Cand->FoundDecl, Cand->Function);
  return true;

case OR_No_Viable_Function:
case OR_Deleted:
  // There was no suitable conversion, or we found a deleted
  // conversion; continue with other checks.
  return false;
}

llvm_unreachable("Invalid OverloadResult!")__builtin_unreachable();
4723}

4725/// Compute an implicit conversion sequence for reference
4726/// initialization.
4727static ImplicitConversionSequence
4728TryReferenceInit(Sema &S, Expr *Init, QualType DeclType,
               SourceLocation DeclLoc,
               bool SuppressUserConversions,
               bool AllowExplicit) {
assert(DeclType->isReferenceType() && "Reference init needs a reference")((void)0);

// Most paths end in a failed conversion.
ImplicitConversionSequence ICS;
ICS.setBad(BadConversionSequence::no_conversion, Init, DeclType);

QualType T1 = DeclType->castAs<ReferenceType>()->getPointeeType();
QualType T2 = Init->getType();

// If the initializer is the address of an overloaded function, try
// to resolve the overloaded function. If all goes well, T2 is the
// type of the resulting function.
if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy) {
  DeclAccessPair Found;
  if (FunctionDecl *Fn = S.ResolveAddressOfOverloadedFunction(Init, DeclType,
                                                              false, Found))
    T2 = Fn->getType();
}

// Compute some basic properties of the types and the initializer.
bool isRValRef = DeclType->isRValueReferenceType();
Expr::Classification InitCategory = Init->Classify(S.Context);

Sema::ReferenceConversions RefConv;
Sema::ReferenceCompareResult RefRelationship =
    S.CompareReferenceRelationship(DeclLoc, T1, T2, &RefConv);

auto SetAsReferenceBinding = [&](bool BindsDirectly) {
  ICS.setStandard();
  ICS.Standard.First = ICK_Identity;
  // FIXME: A reference binding can be a function conversion too. We should
  // consider that when ordering reference-to-function bindings.
  ICS.Standard.Second = (RefConv & Sema::ReferenceConversions::DerivedToBase)
                            ? ICK_Derived_To_Base
                            : (RefConv & Sema::ReferenceConversions::ObjC)
                                  ? ICK_Compatible_Conversion
                                  : ICK_Identity;
  // FIXME: As a speculative fix to a defect introduced by CWG2352, we rank
  // a reference binding that performs a non-top-level qualification
  // conversion as a qualification conversion, not as an identity conversion.
  ICS.Standard.Third = (RefConv &
                            Sema::ReferenceConversions::NestedQualification)
                           ? ICK_Qualification
                           : ICK_Identity;
  ICS.Standard.setFromType(T2);
  ICS.Standard.setToType(0, T2);
  ICS.Standard.setToType(1, T1);
  ICS.Standard.setToType(2, T1);
  ICS.Standard.ReferenceBinding = true;
  ICS.Standard.DirectBinding = BindsDirectly;
  ICS.Standard.IsLvalueReference = !isRValRef;
  ICS.Standard.BindsToFunctionLvalue = T2->isFunctionType();
  ICS.Standard.BindsToRvalue = InitCategory.isRValue();
  ICS.Standard.BindsImplicitObjectArgumentWithoutRefQualifier = false;
  ICS.Standard.ObjCLifetimeConversionBinding =
      (RefConv & Sema::ReferenceConversions::ObjCLifetime) != 0;
  ICS.Standard.CopyConstructor = nullptr;
  ICS.Standard.DeprecatedStringLiteralToCharPtr = false;
};

// C++0x [dcl.init.ref]p5:
//   A reference to type "cv1 T1" is initialized by an expression
//   of type "cv2 T2" as follows:

//     -- If reference is an lvalue reference and the initializer expression
if (!isRValRef) {
  //     -- is an lvalue (but is not a bit-field), and "cv1 T1" is
  //        reference-compatible with "cv2 T2," or
  //
  // Per C++ [over.ics.ref]p4, we don't check the bit-field property here.
  if (InitCategory.isLValue() && RefRelationship == Sema::Ref_Compatible) {
    // C++ [over.ics.ref]p1:
    //   When a parameter of reference type binds directly (8.5.3)
    //   to an argument expression, the implicit conversion sequence
    //   is the identity conversion, unless the argument expression
    //   has a type that is a derived class of the parameter type,
    //   in which case the implicit conversion sequence is a
    //   derived-to-base Conversion (13.3.3.1).
    SetAsReferenceBinding(/*BindsDirectly=*/true);

    // Nothing more to do: the inaccessibility/ambiguity check for
    // derived-to-base conversions is suppressed when we're
    // computing the implicit conversion sequence (C++
    // [over.best.ics]p2).
    return ICS;
  }

  //       -- has a class type (i.e., T2 is a class type), where T1 is
  //          not reference-related to T2, and can be implicitly
  //          converted to an lvalue of type "cv3 T3," where "cv1 T1"
  //          is reference-compatible with "cv3 T3" 92) (this
  //          conversion is selected by enumerating the applicable
  //          conversion functions (13.3.1.6) and choosing the best
  //          one through overload resolution (13.3)),
  if (!SuppressUserConversions && T2->isRecordType() &&
      S.isCompleteType(DeclLoc, T2) &&
      RefRelationship == Sema::Ref_Incompatible) {
    if (FindConversionForRefInit(S, ICS, DeclType, DeclLoc,
                                 Init, T2, /*AllowRvalues=*/false,
                                 AllowExplicit))
      return ICS;
  }
}

//     -- Otherwise, the reference shall be an lvalue reference to a
//        non-volatile const type (i.e., cv1 shall be const), or the reference
//        shall be an rvalue reference.
if (!isRValRef && (!T1.isConstQualified() || T1.isVolatileQualified())) {
  if (InitCategory.isRValue() && RefRelationship != Sema::Ref_Incompatible)
    ICS.setBad(BadConversionSequence::lvalue_ref_to_rvalue, Init, DeclType);
  return ICS;
}

//       -- If the initializer expression
//
//            -- is an xvalue, class prvalue, array prvalue or function
//               lvalue and "cv1 T1" is reference-compatible with "cv2 T2", or
if (RefRelationship == Sema::Ref_Compatible &&
    (InitCategory.isXValue() ||
     (InitCategory.isPRValue() &&
        (T2->isRecordType() || T2->isArrayType())) ||
     (InitCategory.isLValue() && T2->isFunctionType()))) {
  // In C++11, this is always a direct binding. In C++98/03, it's a direct
  // binding unless we're binding to a class prvalue.
  // Note: Although xvalues wouldn't normally show up in C++98/03 code, we
  // allow the use of rvalue references in C++98/03 for the benefit of
  // standard library implementors; therefore, we need the xvalue check here.
  SetAsReferenceBinding(/*BindsDirectly=*/S.getLangOpts().CPlusPlus11 ||
                        !(InitCategory.isPRValue() || T2->isRecordType()));
  return ICS;
}

//            -- has a class type (i.e., T2 is a class type), where T1 is not
//               reference-related to T2, and can be implicitly converted to
//               an xvalue, class prvalue, or function lvalue of type
//               "cv3 T3", where "cv1 T1" is reference-compatible with
//               "cv3 T3",
//
//          then the reference is bound to the value of the initializer
//          expression in the first case and to the result of the conversion
//          in the second case (or, in either case, to an appropriate base
//          class subobject).
if (!SuppressUserConversions && RefRelationship == Sema::Ref_Incompatible &&
    T2->isRecordType() && S.isCompleteType(DeclLoc, T2) &&
    FindConversionForRefInit(S, ICS, DeclType, DeclLoc,
                             Init, T2, /*AllowRvalues=*/true,
                             AllowExplicit)) {
  // In the second case, if the reference is an rvalue reference
  // and the second standard conversion sequence of the
  // user-defined conversion sequence includes an lvalue-to-rvalue
  // conversion, the program is ill-formed.
  if (ICS.isUserDefined() && isRValRef &&
      ICS.UserDefined.After.First == ICK_Lvalue_To_Rvalue)
    ICS.setBad(BadConversionSequence::no_conversion, Init, DeclType);

  return ICS;
}

// A temporary of function type cannot be created; don't even try.
if (T1->isFunctionType())
  return ICS;

//       -- Otherwise, a temporary of type "cv1 T1" is created and
//          initialized from the initializer expression using the
//          rules for a non-reference copy initialization (8.5). The
//          reference is then bound to the temporary. If T1 is
//          reference-related to T2, cv1 must be the same
//          cv-qualification as, or greater cv-qualification than,
//          cv2; otherwise, the program is ill-formed.
if (RefRelationship == Sema::Ref_Related) {
  // If cv1 == cv2 or cv1 is a greater cv-qualified than cv2, then
  // we would be reference-compatible or reference-compatible with
  // added qualification. But that wasn't the case, so the reference
  // initialization fails.
  //
  // Note that we only want to check address spaces and cvr-qualifiers here.
  // ObjC GC, lifetime and unaligned qualifiers aren't important.
  Qualifiers T1Quals = T1.getQualifiers();
  Qualifiers T2Quals = T2.getQualifiers();
  T1Quals.removeObjCGCAttr();
  T1Quals.removeObjCLifetime();
  T2Quals.removeObjCGCAttr();
  T2Quals.removeObjCLifetime();
  // MS compiler ignores __unaligned qualifier for references; do the same.
  T1Quals.removeUnaligned();
  T2Quals.removeUnaligned();
  if (!T1Quals.compatiblyIncludes(T2Quals))
    return ICS;
}

// If at least one of the types is a class type, the types are not
// related, and we aren't allowed any user conversions, the
// reference binding fails. This case is important for breaking
// recursion, since TryImplicitConversion below will attempt to
// create a temporary through the use of a copy constructor.
if (SuppressUserConversions && RefRelationship == Sema::Ref_Incompatible &&
    (T1->isRecordType() || T2->isRecordType()))
  return ICS;

// If T1 is reference-related to T2 and the reference is an rvalue
// reference, the initializer expression shall not be an lvalue.
if (RefRelationship >= Sema::Ref_Related && isRValRef &&
    Init->Classify(S.Context).isLValue()) {
  ICS.setBad(BadConversionSequence::rvalue_ref_to_lvalue, Init, DeclType);
  return ICS;
}

// C++ [over.ics.ref]p2:
//   When a parameter of reference type is not bound directly to
//   an argument expression, the conversion sequence is the one
//   required to convert the argument expression to the
//   underlying type of the reference according to
//   13.3.3.1. Conceptually, this conversion sequence corresponds
//   to copy-initializing a temporary of the underlying type with
//   the argument expression. Any difference in top-level
//   cv-qualification is subsumed by the initialization itself
//   and does not constitute a conversion.
ICS = TryImplicitConversion(S, Init, T1, SuppressUserConversions,
                            AllowedExplicit::None,
                            /*InOverloadResolution=*/false,
                            /*CStyle=*/false,
                            /*AllowObjCWritebackConversion=*/false,
                            /*AllowObjCConversionOnExplicit=*/false);

// Of course, that's still a reference binding.
if (ICS.isStandard()) {
  ICS.Standard.ReferenceBinding = true;
  ICS.Standard.IsLvalueReference = !isRValRef;
  ICS.Standard.BindsToFunctionLvalue = false;
  ICS.Standard.BindsToRvalue = true;
  ICS.Standard.BindsImplicitObjectArgumentWithoutRefQualifier = false;
  ICS.Standard.ObjCLifetimeConversionBinding = false;
} else if (ICS.isUserDefined()) {
  const ReferenceType *LValRefType =
      ICS.UserDefined.ConversionFunction->getReturnType()
          ->getAs<LValueReferenceType>();

  // C++ [over.ics.ref]p3:
  //   Except for an implicit object parameter, for which see 13.3.1, a
  //   standard conversion sequence cannot be formed if it requires [...]
  //   binding an rvalue reference to an lvalue other than a function
  //   lvalue.
  // Note that the function case is not possible here.
  if (isRValRef && LValRefType) {
    ICS.setBad(BadConversionSequence::no_conversion, Init, DeclType);
    return ICS;
  }

  ICS.UserDefined.After.ReferenceBinding = true;
  ICS.UserDefined.After.IsLvalueReference = !isRValRef;
  ICS.UserDefined.After.BindsToFunctionLvalue = false;
  ICS.UserDefined.After.BindsToRvalue = !LValRefType;
  ICS.UserDefined.After.BindsImplicitObjectArgumentWithoutRefQualifier = false;
  ICS.UserDefined.After.ObjCLifetimeConversionBinding = false;
}

return ICS;
4989}

4991static ImplicitConversionSequence
4992TryCopyInitialization(Sema &S, Expr *From, QualType ToType,
                    bool SuppressUserConversions,
                    bool InOverloadResolution,
                    bool AllowObjCWritebackConversion,
                    bool AllowExplicit = false);

4998/// TryListConversion - Try to copy-initialize a value of type ToType from the
4999/// initializer list From.
5000static ImplicitConversionSequence
5001TryListConversion(Sema &S, InitListExpr *From, QualType ToType,
                bool SuppressUserConversions,
                bool InOverloadResolution,
                bool AllowObjCWritebackConversion) {
// C++11 [over.ics.list]p1:
//   When an argument is an initializer list, it is not an expression and
//   special rules apply for converting it to a parameter type.

ImplicitConversionSequence Result;
Result.setBad(BadConversionSequence::no_conversion, From, ToType);

// We need a complete type for what follows. Incomplete types can never be
// initialized from init lists.
if (!S.isCompleteType(From->getBeginLoc(), ToType))
  return Result;

// Per DR1467:
//   If the parameter type is a class X and the initializer list has a single
//   element of type cv U, where U is X or a class derived from X, the
//   implicit conversion sequence is the one required to convert the element
//   to the parameter type.
//
//   Otherwise, if the parameter type is a character array [... ]
//   and the initializer list has a single element that is an
//   appropriately-typed string literal (8.5.2 [dcl.init.string]), the
//   implicit conversion sequence is the identity conversion.
if (From->getNumInits() == 1) {
  if (ToType->isRecordType()) {
    QualType InitType = From->getInit(0)->getType();
    if (S.Context.hasSameUnqualifiedType(InitType, ToType) ||
        S.IsDerivedFrom(From->getBeginLoc(), InitType, ToType))
      return TryCopyInitialization(S, From->getInit(0), ToType,
                                   SuppressUserConversions,
                                   InOverloadResolution,
                                   AllowObjCWritebackConversion);
  }

  if (const auto *AT = S.Context.getAsArrayType(ToType)) {
    if (S.IsStringInit(From->getInit(0), AT)) {
      InitializedEntity Entity =
        InitializedEntity::InitializeParameter(S.Context, ToType,
                                               /*Consumed=*/false);
      if (S.CanPerformCopyInitialization(Entity, From)) {
        Result.setStandard();
        Result.Standard.setAsIdentityConversion();
        Result.Standard.setFromType(ToType);
        Result.Standard.setAllToTypes(ToType);
        return Result;
      }
    }
  }
}

// C++14 [over.ics.list]p2: Otherwise, if the parameter type [...] (below).
// C++11 [over.ics.list]p2:
//   If the parameter type is std::initializer_list<X> or "array of X" and
//   all the elements can be implicitly converted to X, the implicit
//   conversion sequence is the worst conversion necessary to convert an
//   element of the list to X.
//
// C++14 [over.ics.list]p3:
//   Otherwise, if the parameter type is "array of N X", if the initializer
//   list has exactly N elements or if it has fewer than N elements and X is
//   default-constructible, and if all the elements of the initializer list
//   can be implicitly converted to X, the implicit conversion sequence is
//   the worst conversion necessary to convert an element of the list to X.
//
// FIXME: We're missing a lot of these checks.
bool toStdInitializerList = false;
QualType X;
if (ToType->isArrayType())
  X = S.Context.getAsArrayType(ToType)->getElementType();
else
  toStdInitializerList = S.isStdInitializerList(ToType, &X);
if (!X.isNull()) {
  for (unsigned i = 0, e = From->getNumInits(); i < e; ++i) {
    Expr *Init = From->getInit(i);
    ImplicitConversionSequence ICS =
        TryCopyInitialization(S, Init, X, SuppressUserConversions,
                              InOverloadResolution,
                              AllowObjCWritebackConversion);
    // If a single element isn't convertible, fail.
    if (ICS.isBad()) {
      Result = ICS;
      break;
    }
    // Otherwise, look for the worst conversion.
    if (Result.isBad() || CompareImplicitConversionSequences(
                              S, From->getBeginLoc(), ICS, Result) ==
                              ImplicitConversionSequence::Worse)
      Result = ICS;
  }

  // For an empty list, we won't have computed any conversion sequence.
  // Introduce the identity conversion sequence.
  if (From->getNumInits() == 0) {
    Result.setStandard();
    Result.Standard.setAsIdentityConversion();
    Result.Standard.setFromType(ToType);
    Result.Standard.setAllToTypes(ToType);
  }

  Result.setStdInitializerListElement(toStdInitializerList);
  return Result;
}

// C++14 [over.ics.list]p4:
// C++11 [over.ics.list]p3:
//   Otherwise, if the parameter is a non-aggregate class X and overload
//   resolution chooses a single best constructor [...] the implicit
//   conversion sequence is a user-defined conversion sequence. If multiple
//   constructors are viable but none is better than the others, the
//   implicit conversion sequence is a user-defined conversion sequence.
if (ToType->isRecordType() && !ToType->isAggregateType()) {
  // This function can deal with initializer lists.
  return TryUserDefinedConversion(S, From, ToType, SuppressUserConversions,
                                  AllowedExplicit::None,
                                  InOverloadResolution, /*CStyle=*/false,
                                  AllowObjCWritebackConversion,
                                  /*AllowObjCConversionOnExplicit=*/false);
}

// C++14 [over.ics.list]p5:
// C++11 [over.ics.list]p4:
//   Otherwise, if the parameter has an aggregate type which can be
//   initialized from the initializer list [...] the implicit conversion
//   sequence is a user-defined conversion sequence.
if (ToType->isAggregateType()) {
  // Type is an aggregate, argument is an init list. At this point it comes
  // down to checking whether the initialization works.
  // FIXME: Find out whether this parameter is consumed or not.
  InitializedEntity Entity =
      InitializedEntity::InitializeParameter(S.Context, ToType,
                                             /*Consumed=*/false);
  if (S.CanPerformAggregateInitializationForOverloadResolution(Entity,
                                                               From)) {
    Result.setUserDefined();
    Result.UserDefined.Before.setAsIdentityConversion();
    // Initializer lists don't have a type.
    Result.UserDefined.Before.setFromType(QualType());
    Result.UserDefined.Before.setAllToTypes(QualType());

    Result.UserDefined.After.setAsIdentityConversion();
    Result.UserDefined.After.setFromType(ToType);
    Result.UserDefined.After.setAllToTypes(ToType);
    Result.UserDefined.ConversionFunction = nullptr;
  }
  return Result;
}

// C++14 [over.ics.list]p6:
// C++11 [over.ics.list]p5:
//   Otherwise, if the parameter is a reference, see 13.3.3.1.4.
if (ToType->isReferenceType()) {
  // The standard is notoriously unclear here, since 13.3.3.1.4 doesn't
  // mention initializer lists in any way. So we go by what list-
  // initialization would do and try to extrapolate from that.

  QualType T1 = ToType->castAs<ReferenceType>()->getPointeeType();

  // If the initializer list has a single element that is reference-related
  // to the parameter type, we initialize the reference from that.
  if (From->getNumInits() == 1) {
    Expr *Init = From->getInit(0);

    QualType T2 = Init->getType();

    // If the initializer is the address of an overloaded function, try
    // to resolve the overloaded function. If all goes well, T2 is the
    // type of the resulting function.
    if (S.Context.getCanonicalType(T2) == S.Context.OverloadTy) {
      DeclAccessPair Found;
      if (FunctionDecl *Fn = S.ResolveAddressOfOverloadedFunction(
                                 Init, ToType, false, Found))
        T2 = Fn->getType();
    }

    // Compute some basic properties of the types and the initializer.
    Sema::ReferenceCompareResult RefRelationship =
        S.CompareReferenceRelationship(From->getBeginLoc(), T1, T2);

    if (RefRelationship >= Sema::Ref_Related) {
      return TryReferenceInit(S, Init, ToType, /*FIXME*/ From->getBeginLoc(),
                              SuppressUserConversions,
                              /*AllowExplicit=*/false);
    }
  }

  // Otherwise, we bind the reference to a temporary created from the
  // initializer list.
  Result = TryListConversion(S, From, T1, SuppressUserConversions,
                             InOverloadResolution,
                             AllowObjCWritebackConversion);
  if (Result.isFailure())
    return Result;
  assert(!Result.isEllipsis() &&((void)0)
         "Sub-initialization cannot result in ellipsis conversion.")((void)0);

  // Can we even bind to a temporary?
  if (ToType->isRValueReferenceType() ||
      (T1.isConstQualified() && !T1.isVolatileQualified())) {
    StandardConversionSequence &SCS = Result.isStandard() ? Result.Standard :
                                          Result.UserDefined.After;
    SCS.ReferenceBinding = true;
    SCS.IsLvalueReference = ToType->isLValueReferenceType();
    SCS.BindsToRvalue = true;
    SCS.BindsToFunctionLvalue = false;
    SCS.BindsImplicitObjectArgumentWithoutRefQualifier = false;
    SCS.ObjCLifetimeConversionBinding = false;
  } else
    Result.setBad(BadConversionSequence::lvalue_ref_to_rvalue,
                  From, ToType);
  return Result;
}

// C++14 [over.ics.list]p7:
// C++11 [over.ics.list]p6:
//   Otherwise, if the parameter type is not a class:
if (!ToType->isRecordType()) {
  //    - if the initializer list has one element that is not itself an
  //      initializer list, the implicit conversion sequence is the one
  //      required to convert the element to the parameter type.
  unsigned NumInits = From->getNumInits();
  if (NumInits == 1 && !isa<InitListExpr>(From->getInit(0)))
    Result = TryCopyInitialization(S, From->getInit(0), ToType,
                                   SuppressUserConversions,
                                   InOverloadResolution,
                                   AllowObjCWritebackConversion);
  //    - if the initializer list has no elements, the implicit conversion
  //      sequence is the identity conversion.
  else if (NumInits == 0) {
    Result.setStandard();
    Result.Standard.setAsIdentityConversion();
    Result.Standard.setFromType(ToType);
    Result.Standard.setAllToTypes(ToType);
  }
  return Result;
}

// C++14 [over.ics.list]p8:
// C++11 [over.ics.list]p7:
//   In all cases other than those enumerated above, no conversion is possible
return Result;
5244}

5246/// TryCopyInitialization - Try to copy-initialize a value of type
5247/// ToType from the expression From. Return the implicit conversion
5248/// sequence required to pass this argument, which may be a bad
5249/// conversion sequence (meaning that the argument cannot be passed to
5250/// a parameter of this type). If @p SuppressUserConversions, then we
5251/// do not permit any user-defined conversion sequences.
5252static ImplicitConversionSequence
5253TryCopyInitialization(Sema &S, Expr *From, QualType ToType,
                    bool SuppressUserConversions,
                    bool InOverloadResolution,
                    bool AllowObjCWritebackConversion,
                    bool AllowExplicit) {
if (InitListExpr *FromInitList = dyn_cast<InitListExpr>(From))
  return TryListConversion(S, FromInitList, ToType, SuppressUserConversions,
                           InOverloadResolution,AllowObjCWritebackConversion);

if (ToType->isReferenceType())
  return TryReferenceInit(S, From, ToType,
                          /*FIXME:*/ From->getBeginLoc(),
                          SuppressUserConversions, AllowExplicit);

return TryImplicitConversion(S, From, ToType,
                             SuppressUserConversions,
                             AllowedExplicit::None,
                             InOverloadResolution,
                             /*CStyle=*/false,
                             AllowObjCWritebackConversion,
                             /*AllowObjCConversionOnExplicit=*/false);
5274}

5276static bool TryCopyInitialization(const CanQualType FromQTy,
                                const CanQualType ToQTy,
                                Sema &S,
                                SourceLocation Loc,
                                ExprValueKind FromVK) {
OpaqueValueExpr TmpExpr(Loc, FromQTy, FromVK);
ImplicitConversionSequence ICS =
  TryCopyInitialization(S, &TmpExpr, ToQTy, true, true, false);

return !ICS.isBad();
5286}

5288/// TryObjectArgumentInitialization - Try to initialize the object
5289/// parameter of the given member function (@c Method) from the
5290/// expression @p From.
5291static ImplicitConversionSequence
5292TryObjectArgumentInitialization(Sema &S, SourceLocation Loc, QualType FromType,
                              Expr::Classification FromClassification,
                              CXXMethodDecl *Method,
                              CXXRecordDecl *ActingContext) {
QualType ClassType = S.Context.getTypeDeclType(ActingContext);
// [class.dtor]p2: A destructor can be invoked for a const, volatile or
//                 const volatile object.
Qualifiers Quals = Method->getMethodQualifiers();
if (isa<CXXDestructorDecl>(Method)) {
  Quals.addConst();
  Quals.addVolatile();
}

QualType ImplicitParamType = S.Context.getQualifiedType(ClassType, Quals);

// Set up the conversion sequence as a "bad" conversion, to allow us
// to exit early.
ImplicitConversionSequence ICS;

// We need to have an object of class type.
if (const PointerType *PT = FromType->getAs<PointerType>()) {
  FromType = PT->getPointeeType();

  // When we had a pointer, it's implicitly dereferenced, so we
  // better have an lvalue.
  assert(FromClassification.isLValue())((void)0);
}

assert(FromType->isRecordType())((void)0);

// C++0x [over.match.funcs]p4:
//   For non-static member functions, the type of the implicit object
//   parameter is
//
//     - "lvalue reference to cv X" for functions declared without a
//        ref-qualifier or with the & ref-qualifier
//     - "rvalue reference to cv X" for functions declared with the &&
//        ref-qualifier
//
// where X is the class of which the function is a member and cv is the
// cv-qualification on the member function declaration.
//
// However, when finding an implicit conversion sequence for the argument, we
// are not allowed to perform user-defined conversions
// (C++ [over.match.funcs]p5). We perform a simplified version of
// reference binding here, that allows class rvalues to bind to
// non-constant references.

// First check the qualifiers.
QualType FromTypeCanon = S.Context.getCanonicalType(FromType);
if (ImplicitParamType.getCVRQualifiers()
                                  != FromTypeCanon.getLocalCVRQualifiers() &&
    !ImplicitParamType.isAtLeastAsQualifiedAs(FromTypeCanon)) {
  ICS.setBad(BadConversionSequence::bad_qualifiers,
             FromType, ImplicitParamType);
  return ICS;
}

if (FromTypeCanon.hasAddressSpace()) {
  Qualifiers QualsImplicitParamType = ImplicitParamType.getQualifiers();
  Qualifiers QualsFromType = FromTypeCanon.getQualifiers();
  if (!QualsImplicitParamType.isAddressSpaceSupersetOf(QualsFromType)) {
    ICS.setBad(BadConversionSequence::bad_qualifiers,
               FromType, ImplicitParamType);
    return ICS;
  }
}

// Check that we have either the same type or a derived type. It
// affects the conversion rank.
QualType ClassTypeCanon = S.Context.getCanonicalType(ClassType);
ImplicitConversionKind SecondKind;
if (ClassTypeCanon == FromTypeCanon.getLocalUnqualifiedType()) {
  SecondKind = ICK_Identity;
} else if (S.IsDerivedFrom(Loc, FromType, ClassType))
  SecondKind = ICK_Derived_To_Base;
else {
  ICS.setBad(BadConversionSequence::unrelated_class,
             FromType, ImplicitParamType);
  return ICS;
}

// Check the ref-qualifier.
switch (Method->getRefQualifier()) {
case RQ_None:
  // Do nothing; we don't care about lvalueness or rvalueness.
  break;

case RQ_LValue:
  if (!FromClassification.isLValue() && !Quals.hasOnlyConst()) {
    // non-const lvalue reference cannot bind to an rvalue
    ICS.setBad(BadConversionSequence::lvalue_ref_to_rvalue, FromType,
               ImplicitParamType);
    return ICS;
  }
  break;

case RQ_RValue:
  if (!FromClassification.isRValue()) {
    // rvalue reference cannot bind to an lvalue
    ICS.setBad(BadConversionSequence::rvalue_ref_to_lvalue, FromType,
               ImplicitParamType);
    return ICS;
  }
  break;
}

// Success. Mark this as a reference binding.
ICS.setStandard();
ICS.Standard.setAsIdentityConversion();
ICS.Standard.Second = SecondKind;
ICS.Standard.setFromType(FromType);
ICS.Standard.setAllToTypes(ImplicitParamType);
ICS.Standard.ReferenceBinding = true;
ICS.Standard.DirectBinding = true;
ICS.Standard.IsLvalueReference = Method->getRefQualifier() != RQ_RValue;
ICS.Standard.BindsToFunctionLvalue = false;
ICS.Standard.BindsToRvalue = FromClassification.isRValue();
ICS.Standard.BindsImplicitObjectArgumentWithoutRefQualifier
  = (Method->getRefQualifier() == RQ_None);
return ICS;
5413}

5415/// PerformObjectArgumentInitialization - Perform initialization of
5416/// the implicit object parameter for the given Method with the given
5417/// expression.
5418ExprResult
5419Sema::PerformObjectArgumentInitialization(Expr *From,
                                        NestedNameSpecifier *Qualifier,
                                        NamedDecl *FoundDecl,
                                        CXXMethodDecl *Method) {
QualType FromRecordType, DestType;
QualType ImplicitParamRecordType  =
  Method->getThisType()->castAs<PointerType>()->getPointeeType();

Expr::Classification FromClassification;
if (const PointerType *PT = From->getType()->getAs<PointerType>()) {
  FromRecordType = PT->getPointeeType();
  DestType = Method->getThisType();
  FromClassification = Expr::Classification::makeSimpleLValue();
} else {
  FromRecordType = From->getType();
  DestType = ImplicitParamRecordType;
  FromClassification = From->Classify(Context);

  // When performing member access on a prvalue, materialize a temporary.
  if (From->isPRValue()) {
    From = CreateMaterializeTemporaryExpr(FromRecordType, From,
                                          Method->getRefQualifier() !=
                                              RefQualifierKind::RQ_RValue);
  }
}

// Note that we always use the true parent context when performing
// the actual argument initialization.
ImplicitConversionSequence ICS = TryObjectArgumentInitialization(
    *this, From->getBeginLoc(), From->getType(), FromClassification, Method,
    Method->getParent());
if (ICS.isBad()) {
  switch (ICS.Bad.Kind) {
  case BadConversionSequence::bad_qualifiers: {
    Qualifiers FromQs = FromRecordType.getQualifiers();
    Qualifiers ToQs = DestType.getQualifiers();
    unsigned CVR = FromQs.getCVRQualifiers() & ~ToQs.getCVRQualifiers();
    if (CVR) {
      Diag(From->getBeginLoc(), diag::err_member_function_call_bad_cvr)
          << Method->getDeclName() << FromRecordType << (CVR - 1)
          << From->getSourceRange();
      Diag(Method->getLocation(), diag::note_previous_decl)
        << Method->getDeclName();
      return ExprError();
    }
    break;
  }

  case BadConversionSequence::lvalue_ref_to_rvalue:
  case BadConversionSequence::rvalue_ref_to_lvalue: {
    bool IsRValueQualified =
      Method->getRefQualifier() == RefQualifierKind::RQ_RValue;
    Diag(From->getBeginLoc(), diag::err_member_function_call_bad_ref)
        << Method->getDeclName() << FromClassification.isRValue()
        << IsRValueQualified;
    Diag(Method->getLocation(), diag::note_previous_decl)
      << Method->getDeclName();
    return ExprError();
  }

  case BadConversionSequence::no_conversion:
  case BadConversionSequence::unrelated_class:
    break;
  }

  return Diag(From->getBeginLoc(), diag::err_member_function_call_bad_type)
         << ImplicitParamRecordType << FromRecordType
         << From->getSourceRange();
}

if (ICS.Standard.Second == ICK_Derived_To_Base) {
  ExprResult FromRes =
    PerformObjectMemberConversion(From, Qualifier, FoundDecl, Method);
  if (FromRes.isInvalid())
    return ExprError();
  From = FromRes.get();
}

if (!Context.hasSameType(From->getType(), DestType)) {
  CastKind CK;
  QualType PteeTy = DestType->getPointeeType();
  LangAS DestAS =
      PteeTy.isNull() ? DestType.getAddressSpace() : PteeTy.getAddressSpace();
  if (FromRecordType.getAddressSpace() != DestAS)
    CK = CK_AddressSpaceConversion;
  else
    CK = CK_NoOp;
  From = ImpCastExprToType(From, DestType, CK, From->getValueKind()).get();
}
return From;
5509}

5511/// TryContextuallyConvertToBool - Attempt to contextually convert the
5512/// expression From to bool (C++0x [conv]p3).
5513static ImplicitConversionSequence
5514TryContextuallyConvertToBool(Sema &S, Expr *From) {
// C++ [dcl.init]/17.8:
//   - Otherwise, if the initialization is direct-initialization, the source
//     type is std::nullptr_t, and the destination type is bool, the initial
//     value of the object being initialized is false.
if (From->getType()->isNullPtrType())
  return ImplicitConversionSequence::getNullptrToBool(From->getType(),
                                                      S.Context.BoolTy,
                                                      From->isGLValue());

// All other direct-initialization of bool is equivalent to an implicit
// conversion to bool in which explicit conversions are permitted.
return TryImplicitConversion(S, From, S.Context.BoolTy,
                             /*SuppressUserConversions=*/false,
                             AllowedExplicit::Conversions,
                             /*InOverloadResolution=*/false,
                             /*CStyle=*/false,
                             /*AllowObjCWritebackConversion=*/false,
                             /*AllowObjCConversionOnExplicit=*/false);
5533}

5535/// PerformContextuallyConvertToBool - Perform a contextual conversion
5536/// of the expression From to bool (C++0x [conv]p3).
5537ExprResult Sema::PerformContextuallyConvertToBool(Expr *From) {
if (checkPlaceholderForOverload(*this, From))
  return ExprError();

ImplicitConversionSequence ICS = TryContextuallyConvertToBool(*this, From);
if (!ICS.isBad())
  return PerformImplicitConversion(From, Context.BoolTy, ICS, AA_Converting);

if (!DiagnoseMultipleUserDefinedConversion(From, Context.BoolTy))
  return Diag(From->getBeginLoc(), diag::err_typecheck_bool_condition)
         << From->getType() << From->getSourceRange();
return ExprError();
5549}

5551/// Check that the specified conversion is permitted in a converted constant
5552/// expression, according to C++11 [expr.const]p3. Return true if the conversion
5553/// is acceptable.
5554static bool CheckConvertedConstantConversions(Sema &S,
                                            StandardConversionSequence &SCS) {
// Since we know that the target type is an integral or unscoped enumeration
// type, most conversion kinds are impossible. All possible First and Third
// conversions are fine.
switch (SCS.Second) {
case ICK_Identity:
case ICK_Integral_Promotion:
case ICK_Integral_Conversion: // Narrowing conversions are checked elsewhere.
case ICK_Zero_Queue_Conversion:
  return true;

case ICK_Boolean_Conversion:
  // Conversion from an integral or unscoped enumeration type to bool is
  // classified as ICK_Boolean_Conversion, but it's also arguably an integral
  // conversion, so we allow it in a converted constant expression.
  //
  // FIXME: Per core issue 1407, we should not allow this, but that breaks
  // a lot of popular code. We should at least add a warning for this
  // (non-conforming) extension.
  return SCS.getFromType()->isIntegralOrUnscopedEnumerationType() &&
         SCS.getToType(2)->isBooleanType();

case ICK_Pointer_Conversion:
case ICK_Pointer_Member:
  // C++1z: null pointer conversions and null member pointer conversions are
  // only permitted if the source type is std::nullptr_t.
  return SCS.getFromType()->isNullPtrType();

case ICK_Floating_Promotion:
case ICK_Complex_Promotion:
case ICK_Floating_Conversion:
case ICK_Complex_Conversion:
case ICK_Floating_Integral:
case ICK_Compatible_Conversion:
case ICK_Derived_To_Base:
case ICK_Vector_Conversion:
case ICK_SVE_Vector_Conversion:
case ICK_Vector_Splat:
case ICK_Complex_Real:
case ICK_Block_Pointer_Conversion:
case ICK_TransparentUnionConversion:
case ICK_Writeback_Conversion:
case ICK_Zero_Event_Conversion:
case ICK_C_Only_Conversion:
case ICK_Incompatible_Pointer_Conversion:
  return false;

case ICK_Lvalue_To_Rvalue:
case ICK_Array_To_Pointer:
case ICK_Function_To_Pointer:
  llvm_unreachable("found a first conversion kind in Second")__builtin_unreachable();

case ICK_Function_Conversion:
case ICK_Qualification:
  llvm_unreachable("found a third conversion kind in Second")__builtin_unreachable();

case ICK_Num_Conversion_Kinds:
  break;
}

llvm_unreachable("unknown conversion kind")__builtin_unreachable();
5616}

5618/// CheckConvertedConstantExpression - Check that the expression From is a
5619/// converted constant expression of type T, perform the conversion and produce
5620/// the converted expression, per C++11 [expr.const]p3.
5621static ExprResult CheckConvertedConstantExpression(Sema &S, Expr *From,
                                                 QualType T, APValue &Value,
                                                 Sema::CCEKind CCE,
                                                 bool RequireInt,
                                                 NamedDecl *Dest) {
assert(S.getLangOpts().CPlusPlus11 &&((void)0)
       "converted constant expression outside C++11")((void)0);

if (checkPlaceholderForOverload(S, From))
  return ExprError();

// C++1z [expr.const]p3:
//  A converted constant expression of type T is an expression,
//  implicitly converted to type T, where the converted
//  expression is a constant expression and the implicit conversion
//  sequence contains only [... list of conversions ...].
ImplicitConversionSequence ICS =
    CCE == Sema::CCEK_ExplicitBool
        ? TryContextuallyConvertToBool(S, From)
        : TryCopyInitialization(S, From, T,
                                /*SuppressUserConversions=*/false,
                                /*InOverloadResolution=*/false,
                                /*AllowObjCWritebackConversion=*/false,
                                /*AllowExplicit=*/false);
StandardConversionSequence *SCS = nullptr;
switch (ICS.getKind()) {
case ImplicitConversionSequence::StandardConversion:
  SCS = &ICS.Standard;
  break;
case ImplicitConversionSequence::UserDefinedConversion:
  if (T->isRecordType())
    SCS = &ICS.UserDefined.Before;
  else
    SCS = &ICS.UserDefined.After;
  break;
case ImplicitConversionSequence::AmbiguousConversion:
case ImplicitConversionSequence::BadConversion:
  if (!S.DiagnoseMultipleUserDefinedConversion(From, T))
    return S.Diag(From->getBeginLoc(),
                  diag::err_typecheck_converted_constant_expression)
           << From->getType() << From->getSourceRange() << T;
  return ExprError();

case ImplicitConversionSequence::EllipsisConversion:
  llvm_unreachable("ellipsis conversion in converted constant expression")__builtin_unreachable();
}

// Check that we would only use permitted conversions.
if (!CheckConvertedConstantConversions(S, *SCS)) {
  return S.Diag(From->getBeginLoc(),
                diag::err_typecheck_converted_constant_expression_disallowed)
         << From->getType() << From->getSourceRange() << T;
}
// [...] and where the reference binding (if any) binds directly.
if (SCS->ReferenceBinding && !SCS->DirectBinding) {
  return S.Diag(From->getBeginLoc(),
                diag::err_typecheck_converted_constant_expression_indirect)
         << From->getType() << From->getSourceRange() << T;
}

// Usually we can simply apply the ImplicitConversionSequence we formed
// earlier, but that's not guaranteed to work when initializing an object of
// class type.
ExprResult Result;
if (T->isRecordType()) {
  assert(CCE == Sema::CCEK_TemplateArg &&((void)0)
         "unexpected class type converted constant expr")((void)0);
  Result = S.PerformCopyInitialization(
      InitializedEntity::InitializeTemplateParameter(
          T, cast<NonTypeTemplateParmDecl>(Dest)),
      SourceLocation(), From);
} else {
  Result = S.PerformImplicitConversion(From, T, ICS, Sema::AA_Converting);
}
if (Result.isInvalid())
  return Result;

// C++2a [intro.execution]p5:
//   A full-expression is [...] a constant-expression [...]
Result =
    S.ActOnFinishFullExpr(Result.get(), From->getExprLoc(),
                          /*DiscardedValue=*/false, /*IsConstexpr=*/true);
if (Result.isInvalid())
  return Result;

// Check for a narrowing implicit conversion.
bool ReturnPreNarrowingValue = false;
APValue PreNarrowingValue;
QualType PreNarrowingType;
switch (SCS->getNarrowingKind(S.Context, Result.get(), PreNarrowingValue,
                              PreNarrowingType)) {
case NK_Dependent_Narrowing:
  // Implicit conversion to a narrower type, but the expression is
  // value-dependent so we can't tell whether it's actually narrowing.
case NK_Variable_Narrowing:
  // Implicit conversion to a narrower type, and the value is not a constant
  // expression. We'll diagnose this in a moment.
case NK_Not_Narrowing:
  break;

case NK_Constant_Narrowing:
  if (CCE == Sema::CCEK_ArrayBound &&
      PreNarrowingType->isIntegralOrEnumerationType() &&
      PreNarrowingValue.isInt()) {
    // Don't diagnose array bound narrowing here; we produce more precise
    // errors by allowing the un-narrowed value through.
    ReturnPreNarrowingValue = true;
    break;
  }
  S.Diag(From->getBeginLoc(), diag::ext_cce_narrowing)
      << CCE << /*Constant*/ 1
      << PreNarrowingValue.getAsString(S.Context, PreNarrowingType) << T;
  break;

case NK_Type_Narrowing:
  // FIXME: It would be better to diagnose that the expression is not a
  // constant expression.
  S.Diag(From->getBeginLoc(), diag::ext_cce_narrowing)
      << CCE << /*Constant*/ 0 << From->getType() << T;
  break;
}

if (Result.get()->isValueDependent()) {
  Value = APValue();
  return Result;
}

// Check the expression is a constant expression.
SmallVector<PartialDiagnosticAt, 8> Notes;
Expr::EvalResult Eval;
Eval.Diag = &Notes;

ConstantExprKind Kind;
if (CCE == Sema::CCEK_TemplateArg && T->isRecordType())
  Kind = ConstantExprKind::ClassTemplateArgument;
else if (CCE == Sema::CCEK_TemplateArg)
  Kind = ConstantExprKind::NonClassTemplateArgument;
else
  Kind = ConstantExprKind::Normal;

if (!Result.get()->EvaluateAsConstantExpr(Eval, S.Context, Kind) ||
    (RequireInt && !Eval.Val.isInt())) {
  // The expression can't be folded, so we can't keep it at this position in
  // the AST.
  Result = ExprError();
} else {
  Value = Eval.Val;

  if (Notes.empty()) {
    // It's a constant expression.
    Expr *E = ConstantExpr::Create(S.Context, Result.get(), Value);
    if (ReturnPreNarrowingValue)
      Value = std::move(PreNarrowingValue);
    return E;
  }
}

// It's not a constant expression. Produce an appropriate diagnostic.
if (Notes.size() == 1 &&
    Notes[0].second.getDiagID() == diag::note_invalid_subexpr_in_const_expr) {
  S.Diag(Notes[0].first, diag::err_expr_not_cce) << CCE;
} else if (!Notes.empty() && Notes[0].second.getDiagID() ==
                                 diag::note_constexpr_invalid_template_arg) {
  Notes[0].second.setDiagID(diag::err_constexpr_invalid_template_arg);
  for (unsigned I = 0; I < Notes.size(); ++I)
    S.Diag(Notes[I].first, Notes[I].second);
} else {
  S.Diag(From->getBeginLoc(), diag::err_expr_not_cce)
      << CCE << From->getSourceRange();
  for (unsigned I = 0; I < Notes.size(); ++I)
    S.Diag(Notes[I].first, Notes[I].second);
}
return ExprError();
5794}

5796ExprResult Sema::CheckConvertedConstantExpression(Expr *From, QualType T,
                                                APValue &Value, CCEKind CCE,
                                                NamedDecl *Dest) {
return ::CheckConvertedConstantExpression(*this, From, T, Value, CCE, false,
                                          Dest);
5801}

5803ExprResult Sema::CheckConvertedConstantExpression(Expr *From, QualType T,
                                                llvm::APSInt &Value,
                                                CCEKind CCE) {
assert(T->isIntegralOrEnumerationType() && "unexpected converted const type")((void)0);

APValue V;
auto R = ::CheckConvertedConstantExpression(*this, From, T, V, CCE, true,
                                            /*Dest=*/nullptr);
if (!R.isInvalid() && !R.get()->isValueDependent())
  Value = V.getInt();
return R;
5814}


5817/// dropPointerConversions - If the given standard conversion sequence
5818/// involves any pointer conversions, remove them.  This may change
5819/// the result type of the conversion sequence.
5820static void dropPointerConversion(StandardConversionSequence &SCS) {
if (SCS.Second == ICK_Pointer_Conversion) {
  SCS.Second = ICK_Identity;
  SCS.Third = ICK_Identity;
  SCS.ToTypePtrs[2] = SCS.ToTypePtrs[1] = SCS.ToTypePtrs[0];
}
5826}

5828/// TryContextuallyConvertToObjCPointer - Attempt to contextually
5829/// convert the expression From to an Objective-C pointer type.
5830static ImplicitConversionSequence
5831TryContextuallyConvertToObjCPointer(Sema &S, Expr *From) {
// Do an implicit conversion to 'id'.
QualType Ty = S.Context.getObjCIdType();
ImplicitConversionSequence ICS
  = TryImplicitConversion(S, From, Ty,
                          // FIXME: Are these flags correct?
                          /*SuppressUserConversions=*/false,
                          AllowedExplicit::Conversions,
                          /*InOverloadResolution=*/false,
                          /*CStyle=*/false,
                          /*AllowObjCWritebackConversion=*/false,
                          /*AllowObjCConversionOnExplicit=*/true);

// Strip off any final conversions to 'id'.
switch (ICS.getKind()) {
case ImplicitConversionSequence::BadConversion:
case ImplicitConversionSequence::AmbiguousConversion:
case ImplicitConversionSequence::EllipsisConversion:
  break;

case ImplicitConversionSequence::UserDefinedConversion:
  dropPointerConversion(ICS.UserDefined.After);
  break;

case ImplicitConversionSequence::StandardConversion:
  dropPointerConversion(ICS.Standard);
  break;
}

return ICS;
5861}

5863/// PerformContextuallyConvertToObjCPointer - Perform a contextual
5864/// conversion of the expression From to an Objective-C pointer type.
5865/// Returns a valid but null ExprResult if no conversion sequence exists.
5866ExprResult Sema::PerformContextuallyConvertToObjCPointer(Expr *From) {
if (checkPlaceholderForOverload(*this, From))
  return ExprError();

QualType Ty = Context.getObjCIdType();
ImplicitConversionSequence ICS =
  TryContextuallyConvertToObjCPointer(*this, From);
if (!ICS.isBad())
  return PerformImplicitConversion(From, Ty, ICS, AA_Converting);
return ExprResult();
5876}

5878/// Determine whether the provided type is an integral type, or an enumeration
5879/// type of a permitted flavor.
5880bool Sema::ICEConvertDiagnoser::match(QualType T) {
return AllowScopedEnumerations ? T->isIntegralOrEnumerationType()
                               : T->isIntegralOrUnscopedEnumerationType();
5883}

5885static ExprResult
5886diagnoseAmbiguousConversion(Sema &SemaRef, SourceLocation Loc, Expr *From,
                          Sema::ContextualImplicitConverter &Converter,
                          QualType T, UnresolvedSetImpl &ViableConversions) {

if (Converter.Suppress)
  return ExprError();

Converter.diagnoseAmbiguous(SemaRef, Loc, T) << From->getSourceRange();
for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
  CXXConversionDecl *Conv =
      cast<CXXConversionDecl>(ViableConversions[I]->getUnderlyingDecl());
  QualType ConvTy = Conv->getConversionType().getNonReferenceType();
  Converter.noteAmbiguous(SemaRef, Conv, ConvTy);
}
return From;
5901}

5903static bool
5904diagnoseNoViableConversion(Sema &SemaRef, SourceLocation Loc, Expr *&From,
                         Sema::ContextualImplicitConverter &Converter,
                         QualType T, bool HadMultipleCandidates,
                         UnresolvedSetImpl &ExplicitConversions) {
if (ExplicitConversions.size() == 1 && !Converter.Suppress) {
  DeclAccessPair Found = ExplicitConversions[0];
  CXXConversionDecl *Conversion =
      cast<CXXConversionDecl>(Found->getUnderlyingDecl());

  // The user probably meant to invoke the given explicit
  // conversion; use it.
  QualType ConvTy = Conversion->getConversionType().getNonReferenceType();
  std::string TypeStr;
  ConvTy.getAsStringInternal(TypeStr, SemaRef.getPrintingPolicy());

  Converter.diagnoseExplicitConv(SemaRef, Loc, T, ConvTy)
      << FixItHint::CreateInsertion(From->getBeginLoc(),
                                    "static_cast<" + TypeStr + ">(")
      << FixItHint::CreateInsertion(
             SemaRef.getLocForEndOfToken(From->getEndLoc()), ")");
  Converter.noteExplicitConv(SemaRef, Conversion, ConvTy);

  // If we aren't in a SFINAE context, build a call to the
  // explicit conversion function.
  if (SemaRef.isSFINAEContext())
    return true;

  SemaRef.CheckMemberOperatorAccess(From->getExprLoc(), From, nullptr, Found);
  ExprResult Result = SemaRef.BuildCXXMemberCallExpr(From, Found, Conversion,
                                                     HadMultipleCandidates);
  if (Result.isInvalid())
    return true;
  // Record usage of conversion in an implicit cast.
  From = ImplicitCastExpr::Create(SemaRef.Context, Result.get()->getType(),
                                  CK_UserDefinedConversion, Result.get(),
                                  nullptr, Result.get()->getValueKind(),
                                  SemaRef.CurFPFeatureOverrides());
}
return false;
5943}

5945static bool recordConversion(Sema &SemaRef, SourceLocation Loc, Expr *&From,
                           Sema::ContextualImplicitConverter &Converter,
                           QualType T, bool HadMultipleCandidates,
                           DeclAccessPair &Found) {
CXXConversionDecl *Conversion =
    cast<CXXConversionDecl>(Found->getUnderlyingDecl());
SemaRef.CheckMemberOperatorAccess(From->getExprLoc(), From, nullptr, Found);

QualType ToType = Conversion->getConversionType().getNonReferenceType();
if (!Converter.SuppressConversion) {
  if (SemaRef.isSFINAEContext())
    return true;

  Converter.diagnoseConversion(SemaRef, Loc, T, ToType)
      << From->getSourceRange();
}

ExprResult Result = SemaRef.BuildCXXMemberCallExpr(From, Found, Conversion,
                                                   HadMultipleCandidates);
if (Result.isInvalid())
  return true;
// Record usage of conversion in an implicit cast.
From = ImplicitCastExpr::Create(SemaRef.Context, Result.get()->getType(),
                                CK_UserDefinedConversion, Result.get(),
                                nullptr, Result.get()->getValueKind(),
                                SemaRef.CurFPFeatureOverrides());
return false;
5972}

5974static ExprResult finishContextualImplicitConversion(
  Sema &SemaRef, SourceLocation Loc, Expr *From,
  Sema::ContextualImplicitConverter &Converter) {
if (!Converter.match(From->getType()) && !Converter.Suppress)
  Converter.diagnoseNoMatch(SemaRef, Loc, From->getType())
      << From->getSourceRange();

return SemaRef.DefaultLvalueConversion(From);
5982}

5984static void
5985collectViableConversionCandidates(Sema &SemaRef, Expr *From, QualType ToType,
                                UnresolvedSetImpl &ViableConversions,
                                OverloadCandidateSet &CandidateSet) {
for (unsigned I = 0, N = ViableConversions.size(); I != N; ++I) {
  DeclAccessPair FoundDecl = ViableConversions[I];
  NamedDecl *D = FoundDecl.getDecl();
  CXXRecordDecl *ActingContext = cast<CXXRecordDecl>(D->getDeclContext());
  if (isa<UsingShadowDecl>(D))
    D = cast<UsingShadowDecl>(D)->getTargetDecl();

  CXXConversionDecl *Conv;
  FunctionTemplateDecl *ConvTemplate;
  if ((ConvTemplate = dyn_cast<FunctionTemplateDecl>(D)))
    Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
  else
    Conv = cast<CXXConversionDecl>(D);

  if (ConvTemplate)
    SemaRef.AddTemplateConversionCandidate(
        ConvTemplate, FoundDecl, ActingContext, From, ToType, CandidateSet,
        /*AllowObjCConversionOnExplicit=*/false, /*AllowExplicit*/ true);
  else
    SemaRef.AddConversionCandidate(Conv, FoundDecl, ActingContext, From,
                                   ToType, CandidateSet,
                                   /*AllowObjCConversionOnExplicit=*/false,
                                   /*AllowExplicit*/ true);
}
6012}

6014/// Attempt to convert the given expression to a type which is accepted
6015/// by the given converter.
6016///
6017/// This routine will attempt to convert an expression of class type to a
6018/// type accepted by the specified converter. In C++11 and before, the class
6019/// must have a single non-explicit conversion function converting to a matching
6020/// type. In C++1y, there can be multiple such conversion functions, but only
6021/// one target type.
6022///
6023/// \param Loc The source location of the construct that requires the
6024/// conversion.
6025///
6026/// \param From The expression we're converting from.
6027///
6028/// \param Converter Used to control and diagnose the conversion process.
6029///
6030/// \returns The expression, converted to an integral or enumeration type if
6031/// successful.
6032ExprResult Sema::PerformContextualImplicitConversion(
  SourceLocation Loc, Expr *From, ContextualImplicitConverter &Converter) {
// We can't perform any more checking for type-dependent expressions.
if (From->isTypeDependent())
  return From;

// Process placeholders immediately.
if (From->hasPlaceholderType()) {
  ExprResult result = CheckPlaceholderExpr(From);
  if (result.isInvalid())
    return result;
  From = result.get();
}

// If the expression already has a matching type, we're golden.
QualType T = From->getType();
if (Converter.match(T))
  return DefaultLvalueConversion(From);

// FIXME: Check for missing '()' if T is a function type?

// We can only perform contextual implicit conversions on objects of class
// type.
const RecordType *RecordTy = T->getAs<RecordType>();
if (!RecordTy || !getLangOpts().CPlusPlus) {
  if (!Converter.Suppress)
    Converter.diagnoseNoMatch(*this, Loc, T) << From->getSourceRange();
  return From;
}

// We must have a complete class type.
struct TypeDiagnoserPartialDiag : TypeDiagnoser {
  ContextualImplicitConverter &Converter;
  Expr *From;

  TypeDiagnoserPartialDiag(ContextualImplicitConverter &Converter, Expr *From)
      : Converter(Converter), From(From) {}

  void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
    Converter.diagnoseIncomplete(S, Loc, T) << From->getSourceRange();
  }
} IncompleteDiagnoser(Converter, From);

if (Converter.Suppress ? !isCompleteType(Loc, T)
                       : RequireCompleteType(Loc, T, IncompleteDiagnoser))
  return From;

// Look for a conversion to an integral or enumeration type.
UnresolvedSet<4>
    ViableConversions; // These are *potentially* viable in C++1y.
UnresolvedSet<4> ExplicitConversions;
const auto &Conversions =
    cast<CXXRecordDecl>(RecordTy->getDecl())->getVisibleConversionFunctions();

bool HadMultipleCandidates =
    (std::distance(Conversions.begin(), Conversions.end()) > 1);

// To check that there is only one target type, in C++1y:
QualType ToType;
bool HasUniqueTargetType = true;

// Collect explicit or viable (potentially in C++1y) conversions.
for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
  NamedDecl *D = (*I)->getUnderlyingDecl();
  CXXConversionDecl *Conversion;
  FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
  if (ConvTemplate) {
    if (getLangOpts().CPlusPlus14)
      Conversion = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
    else
      continue; // C++11 does not consider conversion operator templates(?).
  } else
    Conversion = cast<CXXConversionDecl>(D);

  assert((!ConvTemplate || getLangOpts().CPlusPlus14) &&((void)0)
         "Conversion operator templates are considered potentially "((void)0)
         "viable in C++1y")((void)0);

  QualType CurToType = Conversion->getConversionType().getNonReferenceType();
  if (Converter.match(CurToType) || ConvTemplate) {

    if (Conversion->isExplicit()) {
      // FIXME: For C++1y, do we need this restriction?
      // cf. diagnoseNoViableConversion()
      if (!ConvTemplate)
        ExplicitConversions.addDecl(I.getDecl(), I.getAccess());
    } else {
      if (!ConvTemplate && getLangOpts().CPlusPlus14) {
        if (ToType.isNull())
          ToType = CurToType.getUnqualifiedType();
        else if (HasUniqueTargetType &&
                 (CurToType.getUnqualifiedType() != ToType))
          HasUniqueTargetType = false;
      }
      ViableConversions.addDecl(I.getDecl(), I.getAccess());
    }
  }
}

if (getLangOpts().CPlusPlus14) {
  // C++1y [conv]p6:
  // ... An expression e of class type E appearing in such a context
  // is said to be contextually implicitly converted to a specified
  // type T and is well-formed if and only if e can be implicitly
  // converted to a type T that is determined as follows: E is searched
  // for conversion functions whose return type is cv T or reference to
  // cv T such that T is allowed by the context. There shall be
  // exactly one such T.

  // If no unique T is found:
  if (ToType.isNull()) {
    if (diagnoseNoViableConversion(*this, Loc, From, Converter, T,
                                   HadMultipleCandidates,
                                   ExplicitConversions))
      return ExprError();
    return finishContextualImplicitConversion(*this, Loc, From, Converter);
  }

  // If more than one unique Ts are found:
  if (!HasUniqueTargetType)
    return diagnoseAmbiguousConversion(*this, Loc, From, Converter, T,
                                       ViableConversions);

  // If one unique T is found:
  // First, build a candidate set from the previously recorded
  // potentially viable conversions.
  OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
  collectViableConversionCandidates(*this, From, ToType, ViableConversions,
                                    CandidateSet);

  // Then, perform overload resolution over the candidate set.
  OverloadCandidateSet::iterator Best;
  switch (CandidateSet.BestViableFunction(*this, Loc, Best)) {
  case OR_Success: {
    // Apply this conversion.
    DeclAccessPair Found =
        DeclAccessPair::make(Best->Function, Best->FoundDecl.getAccess());
    if (recordConversion(*this, Loc, From, Converter, T,
                         HadMultipleCandidates, Found))
      return ExprError();
    break;
  }
  case OR_Ambiguous:
    return diagnoseAmbiguousConversion(*this, Loc, From, Converter, T,
                                       ViableConversions);
  case OR_No_Viable_Function:
    if (diagnoseNoViableConversion(*this, Loc, From, Converter, T,
                                   HadMultipleCandidates,
                                   ExplicitConversions))
      return ExprError();
    LLVM_FALLTHROUGH[[gnu::fallthrough]];
  case OR_Deleted:
    // We'll complain below about a non-integral condition type.
    break;
  }
} else {
  switch (ViableConversions.size()) {
  case 0: {
    if (diagnoseNoViableConversion(*this, Loc, From, Converter, T,
                                   HadMultipleCandidates,
                                   ExplicitConversions))
      return ExprError();

    // We'll complain below about a non-integral condition type.
    break;
  }
  case 1: {
    // Apply this conversion.
    DeclAccessPair Found = ViableConversions[0];
    if (recordConversion(*this, Loc, From, Converter, T,
                         HadMultipleCandidates, Found))
      return ExprError();
    break;
  }
  default:
    return diagnoseAmbiguousConversion(*this, Loc, From, Converter, T,
                                       ViableConversions);
  }
}

return finishContextualImplicitConversion(*this, Loc, From, Converter);
6213}

6215/// IsAcceptableNonMemberOperatorCandidate - Determine whether Fn is
6216/// an acceptable non-member overloaded operator for a call whose
6217/// arguments have types T1 (and, if non-empty, T2). This routine
6218/// implements the check in C++ [over.match.oper]p3b2 concerning
6219/// enumeration types.
6220static bool IsAcceptableNonMemberOperatorCandidate(ASTContext &Context,
                                                 FunctionDecl *Fn,
                                                 ArrayRef<Expr *> Args) {
QualType T1 = Args[0]->getType();
QualType T2 = Args.size() > 1 ? Args[1]->getType() : QualType();

if (T1->isDependentType() || (!T2.isNull() && T2->isDependentType()))
  return true;

if (T1->isRecordType() || (!T2.isNull() && T2->isRecordType()))
  return true;

const auto *Proto = Fn->getType()->castAs<FunctionProtoType>();
if (Proto->getNumParams() < 1)
  return false;

if (T1->isEnumeralType()) {
  QualType ArgType = Proto->getParamType(0).getNonReferenceType();
  if (Context.hasSameUnqualifiedType(T1, ArgType))
    return true;
}

if (Proto->getNumParams() < 2)
  return false;

if (!T2.isNull() && T2->isEnumeralType()) {
  QualType ArgType = Proto->getParamType(1).getNonReferenceType();
  if (Context.hasSameUnqualifiedType(T2, ArgType))
    return true;
}

return false;
6252}

6254/// AddOverloadCandidate - Adds the given function to the set of
6255/// candidate functions, using the given function call arguments.  If
6256/// @p SuppressUserConversions, then don't allow user-defined
6257/// conversions via constructors or conversion operators.
6258///
6259/// \param PartialOverloading true if we are performing "partial" overloading
6260/// based on an incomplete set of function arguments. This feature is used by
6261/// code completion.
6262void Sema::AddOverloadCandidate(
  FunctionDecl *Function, DeclAccessPair FoundDecl, ArrayRef<Expr *> Args,
  OverloadCandidateSet &CandidateSet, bool SuppressUserConversions,
  bool PartialOverloading, bool AllowExplicit, bool AllowExplicitConversions,
  ADLCallKind IsADLCandidate, ConversionSequenceList EarlyConversions,
  OverloadCandidateParamOrder PO) {
const FunctionProtoType *Proto
  = dyn_cast<FunctionProtoType>(Function->getType()->getAs<FunctionType>());
assert(Proto && "Functions without a prototype cannot be overloaded")((void)0);
assert(!Function->getDescribedFunctionTemplate() &&((void)0)
       "Use AddTemplateOverloadCandidate for function templates")((void)0);

if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
  if (!isa<CXXConstructorDecl>(Method)) {
    // If we get here, it's because we're calling a member function
    // that is named without a member access expression (e.g.,
    // "this->f") that was either written explicitly or created
    // implicitly. This can happen with a qualified call to a member
    // function, e.g., X::f(). We use an empty type for the implied
    // object argument (C++ [over.call.func]p3), and the acting context
    // is irrelevant.
    AddMethodCandidate(Method, FoundDecl, Method->getParent(), QualType(),
                       Expr::Classification::makeSimpleLValue(), Args,
                       CandidateSet, SuppressUserConversions,
                       PartialOverloading, EarlyConversions, PO);
    return;
  }
  // We treat a constructor like a non-member function, since its object
  // argument doesn't participate in overload resolution.
}

if (!CandidateSet.isNewCandidate(Function, PO))
  return;

// C++11 [class.copy]p11: [DR1402]
//   A defaulted move constructor that is defined as deleted is ignored by
//   overload resolution.
CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(Function);
if (Constructor && Constructor->isDefaulted() && Constructor->isDeleted() &&
    Constructor->isMoveConstructor())
  return;

// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

// C++ [over.match.oper]p3:
//   if no operand has a class type, only those non-member functions in the
//   lookup set that have a first parameter of type T1 or "reference to
//   (possibly cv-qualified) T1", when T1 is an enumeration type, or (if there
//   is a right operand) a second parameter of type T2 or "reference to
//   (possibly cv-qualified) T2", when T2 is an enumeration type, are
//   candidate functions.
if (CandidateSet.getKind() == OverloadCandidateSet::CSK_Operator &&
    !IsAcceptableNonMemberOperatorCandidate(Context, Function, Args))
  return;

// Add this candidate
OverloadCandidate &Candidate =
    CandidateSet.addCandidate(Args.size(), EarlyConversions);
Candidate.FoundDecl = FoundDecl;
Candidate.Function = Function;
Candidate.Viable = true;
Candidate.RewriteKind =
    CandidateSet.getRewriteInfo().getRewriteKind(Function, PO);
Candidate.IsSurrogate = false;
Candidate.IsADLCandidate = IsADLCandidate;
Candidate.IgnoreObjectArgument = false;
Candidate.ExplicitCallArguments = Args.size();

// Explicit functions are not actually candidates at all if we're not
// allowing them in this context, but keep them around so we can point
// to them in diagnostics.
if (!AllowExplicit && ExplicitSpecifier::getFromDecl(Function).isExplicit()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_explicit;
  return;
}

if (Function->isMultiVersion() && Function->hasAttr<TargetAttr>() &&
    !Function->getAttr<TargetAttr>()->isDefaultVersion()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_non_default_multiversion_function;
  return;
}

if (Constructor) {
  // C++ [class.copy]p3:
  //   A member function template is never instantiated to perform the copy
  //   of a class object to an object of its class type.
  QualType ClassType = Context.getTypeDeclType(Constructor->getParent());
  if (Args.size() == 1 && Constructor->isSpecializationCopyingObject() &&
      (Context.hasSameUnqualifiedType(ClassType, Args[0]->getType()) ||
       IsDerivedFrom(Args[0]->getBeginLoc(), Args[0]->getType(),
                     ClassType))) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_illegal_constructor;
    return;
  }

  // C++ [over.match.funcs]p8: (proposed DR resolution)
  //   A constructor inherited from class type C that has a first parameter
  //   of type "reference to P" (including such a constructor instantiated
  //   from a template) is excluded from the set of candidate functions when
  //   constructing an object of type cv D if the argument list has exactly
  //   one argument and D is reference-related to P and P is reference-related
  //   to C.
  auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(FoundDecl.getDecl());
  if (Shadow && Args.size() == 1 && Constructor->getNumParams() >= 1 &&
      Constructor->getParamDecl(0)->getType()->isReferenceType()) {
    QualType P = Constructor->getParamDecl(0)->getType()->getPointeeType();
    QualType C = Context.getRecordType(Constructor->getParent());
    QualType D = Context.getRecordType(Shadow->getParent());
    SourceLocation Loc = Args.front()->getExprLoc();
    if ((Context.hasSameUnqualifiedType(P, C) || IsDerivedFrom(Loc, P, C)) &&
        (Context.hasSameUnqualifiedType(D, P) || IsDerivedFrom(Loc, D, P))) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_inhctor_slice;
      return;
    }
  }

  // Check that the constructor is capable of constructing an object in the
  // destination address space.
  if (!Qualifiers::isAddressSpaceSupersetOf(
          Constructor->getMethodQualifiers().getAddressSpace(),
          CandidateSet.getDestAS())) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_object_addrspace_mismatch;
  }
}

unsigned NumParams = Proto->getNumParams();

// (C++ 13.3.2p2): A candidate function having fewer than m
// parameters is viable only if it has an ellipsis in its parameter
// list (8.3.5).
if (TooManyArguments(NumParams, Args.size(), PartialOverloading) &&
    !Proto->isVariadic()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_many_arguments;
  return;
}

// (C++ 13.3.2p2): A candidate function having more than m parameters
// is viable only if the (m+1)st parameter has a default argument
// (8.3.6). For the purposes of overload resolution, the
// parameter list is truncated on the right, so that there are
// exactly m parameters.
unsigned MinRequiredArgs = Function->getMinRequiredArguments();
if (Args.size() < MinRequiredArgs && !PartialOverloading) {
  // Not enough arguments.
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_few_arguments;
  return;
}

// (CUDA B.1): Check for invalid calls between targets.
if (getLangOpts().CUDA)
  if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext))
    // Skip the check for callers that are implicit members, because in this
    // case we may not yet know what the member's target is; the target is
    // inferred for the member automatically, based on the bases and fields of
    // the class.
    if (!Caller->isImplicit() && !IsAllowedCUDACall(Caller, Function)) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_bad_target;
      return;
    }

if (Function->getTrailingRequiresClause()) {
  ConstraintSatisfaction Satisfaction;
  if (CheckFunctionConstraints(Function, Satisfaction) ||
      !Satisfaction.IsSatisfied) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_constraints_not_satisfied;
    return;
  }
}

// Determine the implicit conversion sequences for each of the
// arguments.
for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
  unsigned ConvIdx =
      PO == OverloadCandidateParamOrder::Reversed ? 1 - ArgIdx : ArgIdx;
  if (Candidate.Conversions[ConvIdx].isInitialized()) {
    // We already formed a conversion sequence for this parameter during
    // template argument deduction.
  } else if (ArgIdx < NumParams) {
    // (C++ 13.3.2p3): for F to be a viable function, there shall
    // exist for each argument an implicit conversion sequence
    // (13.3.3.1) that converts that argument to the corresponding
    // parameter of F.
    QualType ParamType = Proto->getParamType(ArgIdx);
    Candidate.Conversions[ConvIdx] = TryCopyInitialization(
        *this, Args[ArgIdx], ParamType, SuppressUserConversions,
        /*InOverloadResolution=*/true,
        /*AllowObjCWritebackConversion=*/
        getLangOpts().ObjCAutoRefCount, AllowExplicitConversions);
    if (Candidate.Conversions[ConvIdx].isBad()) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_bad_conversion;
      return;
    }
  } else {
    // (C++ 13.3.2p2): For the purposes of overload resolution, any
    // argument for which there is no corresponding parameter is
    // considered to ""match the ellipsis" (C+ 13.3.3.1.3).
    Candidate.Conversions[ConvIdx].setEllipsis();
  }
}

if (EnableIfAttr *FailedAttr =
        CheckEnableIf(Function, CandidateSet.getLocation(), Args)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_enable_if;
  Candidate.DeductionFailure.Data = FailedAttr;
  return;
}
6481}

6483ObjCMethodDecl *
6484Sema::SelectBestMethod(Selector Sel, MultiExprArg Args, bool IsInstance,
                     SmallVectorImpl<ObjCMethodDecl *> &Methods) {
if (Methods.size() <= 1)
  return nullptr;

for (unsigned b = 0, e = Methods.size(); b < e; b++) {
  bool Match = true;
  ObjCMethodDecl *Method = Methods[b];
  unsigned NumNamedArgs = Sel.getNumArgs();
  // Method might have more arguments than selector indicates. This is due
  // to addition of c-style arguments in method.
  if (Method->param_size() > NumNamedArgs)
    NumNamedArgs = Method->param_size();
  if (Args.size() < NumNamedArgs)
    continue;

  for (unsigned i = 0; i < NumNamedArgs; i++) {
    // We can't do any type-checking on a type-dependent argument.
    if (Args[i]->isTypeDependent()) {
      Match = false;
      break;
    }

    ParmVarDecl *param = Method->parameters()[i];
    Expr *argExpr = Args[i];
    assert(argExpr && "SelectBestMethod(): missing expression")((void)0);

    // Strip the unbridged-cast placeholder expression off unless it's
    // a consumed argument.
    if (argExpr->hasPlaceholderType(BuiltinType::ARCUnbridgedCast) &&
        !param->hasAttr<CFConsumedAttr>())
      argExpr = stripARCUnbridgedCast(argExpr);

    // If the parameter is __unknown_anytype, move on to the next method.
    if (param->getType() == Context.UnknownAnyTy) {
      Match = false;
      break;
    }

    ImplicitConversionSequence ConversionState
      = TryCopyInitialization(*this, argExpr, param->getType(),
                              /*SuppressUserConversions*/false,
                              /*InOverloadResolution=*/true,
                              /*AllowObjCWritebackConversion=*/
                              getLangOpts().ObjCAutoRefCount,
                              /*AllowExplicit*/false);
    // This function looks for a reasonably-exact match, so we consider
    // incompatible pointer conversions to be a failure here.
    if (ConversionState.isBad() ||
        (ConversionState.isStandard() &&
         ConversionState.Standard.Second ==
             ICK_Incompatible_Pointer_Conversion)) {
      Match = false;
      break;
    }
  }
  // Promote additional arguments to variadic methods.
  if (Match && Method->isVariadic()) {
    for (unsigned i = NumNamedArgs, e = Args.size(); i < e; ++i) {
      if (Args[i]->isTypeDependent()) {
        Match = false;
        break;
      }
      ExprResult Arg = DefaultVariadicArgumentPromotion(Args[i], VariadicMethod,
                                                        nullptr);
      if (Arg.isInvalid()) {
        Match = false;
        break;
      }
    }
  } else {
    // Check for extra arguments to non-variadic methods.
    if (Args.size() != NumNamedArgs)
      Match = false;
    else if (Match && NumNamedArgs == 0 && Methods.size() > 1) {
      // Special case when selectors have no argument. In this case, select
      // one with the most general result type of 'id'.
      for (unsigned b = 0, e = Methods.size(); b < e; b++) {
        QualType ReturnT = Methods[b]->getReturnType();
        if (ReturnT->isObjCIdType())
          return Methods[b];
      }
    }
  }

  if (Match)
    return Method;
}
return nullptr;
6573}

6575static bool convertArgsForAvailabilityChecks(
  Sema &S, FunctionDecl *Function, Expr *ThisArg, SourceLocation CallLoc,
  ArrayRef<Expr *> Args, Sema::SFINAETrap &Trap, bool MissingImplicitThis,
  Expr *&ConvertedThis, SmallVectorImpl<Expr *> &ConvertedArgs) {
if (ThisArg) {
  CXXMethodDecl *Method = cast<CXXMethodDecl>(Function);
  assert(!isa<CXXConstructorDecl>(Method) &&((void)0)
         "Shouldn't have `this` for ctors!")((void)0);
  assert(!Method->isStatic() && "Shouldn't have `this` for static methods!")((void)0);
  ExprResult R = S.PerformObjectArgumentInitialization(
      ThisArg, /*Qualifier=*/nullptr, Method, Method);
  if (R.isInvalid())
    return false;
  ConvertedThis = R.get();
} else {
  if (auto *MD = dyn_cast<CXXMethodDecl>(Function)) {
    (void)MD;
    assert((MissingImplicitThis || MD->isStatic() ||((void)0)
            isa<CXXConstructorDecl>(MD)) &&((void)0)
           "Expected `this` for non-ctor instance methods")((void)0);
  }
  ConvertedThis = nullptr;
}

// Ignore any variadic arguments. Converting them is pointless, since the
// user can't refer to them in the function condition.
unsigned ArgSizeNoVarargs = std::min(Function->param_size(), Args.size());

// Convert the arguments.
for (unsigned I = 0; I != ArgSizeNoVarargs; ++I) {
  ExprResult R;
  R = S.PerformCopyInitialization(InitializedEntity::InitializeParameter(
                                      S.Context, Function->getParamDecl(I)),
                                  SourceLocation(), Args[I]);

  if (R.isInvalid())
    return false;

  ConvertedArgs.push_back(R.get());
}

if (Trap.hasErrorOccurred())
  return false;

// Push default arguments if needed.
if (!Function->isVariadic() && Args.size() < Function->getNumParams()) {
  for (unsigned i = Args.size(), e = Function->getNumParams(); i != e; ++i) {
    ParmVarDecl *P = Function->getParamDecl(i);
    if (!P->hasDefaultArg())
      return false;
    ExprResult R = S.BuildCXXDefaultArgExpr(CallLoc, Function, P);
    if (R.isInvalid())
      return false;
    ConvertedArgs.push_back(R.get());
  }

  if (Trap.hasErrorOccurred())
    return false;
}
return true;
6635}

6637EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function,
                                SourceLocation CallLoc,
                                ArrayRef<Expr *> Args,
                                bool MissingImplicitThis) {
auto EnableIfAttrs = Function->specific_attrs<EnableIfAttr>();
if (EnableIfAttrs.begin() == EnableIfAttrs.end())
  return nullptr;

SFINAETrap Trap(*this);
SmallVector<Expr *, 16> ConvertedArgs;
// FIXME: We should look into making enable_if late-parsed.
Expr *DiscardedThis;
if (!convertArgsForAvailabilityChecks(
        *this, Function, /*ThisArg=*/nullptr, CallLoc, Args, Trap,
        /*MissingImplicitThis=*/true, DiscardedThis, ConvertedArgs))
  return *EnableIfAttrs.begin();

for (auto *EIA : EnableIfAttrs) {
  APValue Result;
  // FIXME: This doesn't consider value-dependent cases, because doing so is
  // very difficult. Ideally, we should handle them more gracefully.
  if (EIA->getCond()->isValueDependent() ||
      !EIA->getCond()->EvaluateWithSubstitution(
          Result, Context, Function, llvm::makeArrayRef(ConvertedArgs)))
    return EIA;

  if (!Result.isInt() || !Result.getInt().getBoolValue())
    return EIA;
}
return nullptr;
6667}

6669template <typename CheckFn>
6670static bool diagnoseDiagnoseIfAttrsWith(Sema &S, const NamedDecl *ND,
                                      bool ArgDependent, SourceLocation Loc,
                                      CheckFn &&IsSuccessful) {
SmallVector<const DiagnoseIfAttr *, 8> Attrs;
for (const auto *DIA : ND->specific_attrs<DiagnoseIfAttr>()) {
  if (ArgDependent == DIA->getArgDependent())
    Attrs.push_back(DIA);
}

// Common case: No diagnose_if attributes, so we can quit early.
if (Attrs.empty())
  return false;

auto WarningBegin = std::stable_partition(
    Attrs.begin(), Attrs.end(),
    [](const DiagnoseIfAttr *DIA) { return DIA->isError(); });

// Note that diagnose_if attributes are late-parsed, so they appear in the
// correct order (unlike enable_if attributes).
auto ErrAttr = llvm::find_if(llvm::make_range(Attrs.begin(), WarningBegin),
                             IsSuccessful);
if (ErrAttr != WarningBegin) {
  const DiagnoseIfAttr *DIA = *ErrAttr;
  S.Diag(Loc, diag::err_diagnose_if_succeeded) << DIA->getMessage();
  S.Diag(DIA->getLocation(), diag::note_from_diagnose_if)
      << DIA->getParent() << DIA->getCond()->getSourceRange();
  return true;
}

for (const auto *DIA : llvm::make_range(WarningBegin, Attrs.end()))
  if (IsSuccessful(DIA)) {
    S.Diag(Loc, diag::warn_diagnose_if_succeeded) << DIA->getMessage();
    S.Diag(DIA->getLocation(), diag::note_from_diagnose_if)
        << DIA->getParent() << DIA->getCond()->getSourceRange();
  }

return false;
6707}

6709bool Sema::diagnoseArgDependentDiagnoseIfAttrs(const FunctionDecl *Function,
                                             const Expr *ThisArg,
                                             ArrayRef<const Expr *> Args,
                                             SourceLocation Loc) {
return diagnoseDiagnoseIfAttrsWith(
    *this, Function, /*ArgDependent=*/true, Loc,
    [&](const DiagnoseIfAttr *DIA) {
      APValue Result;
      // It's sane to use the same Args for any redecl of this function, since
      // EvaluateWithSubstitution only cares about the position of each
      // argument in the arg list, not the ParmVarDecl* it maps to.
      if (!DIA->getCond()->EvaluateWithSubstitution(
              Result, Context, cast<FunctionDecl>(DIA->getParent()), Args, ThisArg))
        return false;
      return Result.isInt() && Result.getInt().getBoolValue();
    });
6725}

6727bool Sema::diagnoseArgIndependentDiagnoseIfAttrs(const NamedDecl *ND,
                                               SourceLocation Loc) {
return diagnoseDiagnoseIfAttrsWith(
    *this, ND, /*ArgDependent=*/false, Loc,
    [&](const DiagnoseIfAttr *DIA) {
      bool Result;
      return DIA->getCond()->EvaluateAsBooleanCondition(Result, Context) &&
             Result;
    });
6736}

6738/// Add all of the function declarations in the given function set to
6739/// the overload candidate set.
6740void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
                               ArrayRef<Expr *> Args,
                               OverloadCandidateSet &CandidateSet,
                               TemplateArgumentListInfo *ExplicitTemplateArgs,
                               bool SuppressUserConversions,
                               bool PartialOverloading,
                               bool FirstArgumentIsBase) {
for (UnresolvedSetIterator F = Fns.begin(), E = Fns.end(); F != E; ++F) {
  NamedDecl *D = F.getDecl()->getUnderlyingDecl();
  ArrayRef<Expr *> FunctionArgs = Args;

  FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D);
  FunctionDecl *FD =
      FunTmpl ? FunTmpl->getTemplatedDecl() : cast<FunctionDecl>(D);

  if (isa<CXXMethodDecl>(FD) && !cast<CXXMethodDecl>(FD)->isStatic()) {
    QualType ObjectType;
    Expr::Classification ObjectClassification;
    if (Args.size() > 0) {
      if (Expr *E = Args[0]) {
        // Use the explicit base to restrict the lookup:
        ObjectType = E->getType();
        // Pointers in the object arguments are implicitly dereferenced, so we
        // always classify them as l-values.
        if (!ObjectType.isNull() && ObjectType->isPointerType())
          ObjectClassification = Expr::Classification::makeSimpleLValue();
        else
          ObjectClassification = E->Classify(Context);
      } // .. else there is an implicit base.
      FunctionArgs = Args.slice(1);
    }
    if (FunTmpl) {
      AddMethodTemplateCandidate(
          FunTmpl, F.getPair(),
          cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
          ExplicitTemplateArgs, ObjectType, ObjectClassification,
          FunctionArgs, CandidateSet, SuppressUserConversions,
          PartialOverloading);
    } else {
      AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
                         cast<CXXMethodDecl>(FD)->getParent(), ObjectType,
                         ObjectClassification, FunctionArgs, CandidateSet,
                         SuppressUserConversions, PartialOverloading);
    }
  } else {
    // This branch handles both standalone functions and static methods.

    // Slice the first argument (which is the base) when we access
    // static method as non-static.
    if (Args.size() > 0 &&
        (!Args[0] || (FirstArgumentIsBase && isa<CXXMethodDecl>(FD) &&
                      !isa<CXXConstructorDecl>(FD)))) {
      assert(cast<CXXMethodDecl>(FD)->isStatic())((void)0);
      FunctionArgs = Args.slice(1);
    }
    if (FunTmpl) {
      AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
                                   ExplicitTemplateArgs, FunctionArgs,
                                   CandidateSet, SuppressUserConversions,
                                   PartialOverloading);
    } else {
      AddOverloadCandidate(FD, F.getPair(), FunctionArgs, CandidateSet,
                           SuppressUserConversions, PartialOverloading);
    }
  }
}
6806}

6808/// AddMethodCandidate - Adds a named decl (which is some kind of
6809/// method) as a method candidate to the given overload set.
6810void Sema::AddMethodCandidate(DeclAccessPair FoundDecl, QualType ObjectType,
                            Expr::Classification ObjectClassification,
                            ArrayRef<Expr *> Args,
                            OverloadCandidateSet &CandidateSet,
                            bool SuppressUserConversions,
                            OverloadCandidateParamOrder PO) {
NamedDecl *Decl = FoundDecl.getDecl();
CXXRecordDecl *ActingContext = cast<CXXRecordDecl>(Decl->getDeclContext());

if (isa<UsingShadowDecl>(Decl))
  Decl = cast<UsingShadowDecl>(Decl)->getTargetDecl();

if (FunctionTemplateDecl *TD = dyn_cast<FunctionTemplateDecl>(Decl)) {
  assert(isa<CXXMethodDecl>(TD->getTemplatedDecl()) &&((void)0)
         "Expected a member function template")((void)0);
  AddMethodTemplateCandidate(TD, FoundDecl, ActingContext,
                             /*ExplicitArgs*/ nullptr, ObjectType,
                             ObjectClassification, Args, CandidateSet,
                             SuppressUserConversions, false, PO);
} else {
  AddMethodCandidate(cast<CXXMethodDecl>(Decl), FoundDecl, ActingContext,
                     ObjectType, ObjectClassification, Args, CandidateSet,
                     SuppressUserConversions, false, None, PO);
}
6834}

6836/// AddMethodCandidate - Adds the given C++ member function to the set
6837/// of candidate functions, using the given function call arguments
6838/// and the object argument (@c Object). For example, in a call
6839/// @c o.f(a1,a2), @c Object will contain @c o and @c Args will contain
6840/// both @c a1 and @c a2. If @p SuppressUserConversions, then don't
6841/// allow user-defined conversions via constructors or conversion
6842/// operators.
6843void
6844Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
                       CXXRecordDecl *ActingContext, QualType ObjectType,
                       Expr::Classification ObjectClassification,
                       ArrayRef<Expr *> Args,
                       OverloadCandidateSet &CandidateSet,
                       bool SuppressUserConversions,
                       bool PartialOverloading,
                       ConversionSequenceList EarlyConversions,
                       OverloadCandidateParamOrder PO) {
const FunctionProtoType *Proto
  = dyn_cast<FunctionProtoType>(Method->getType()->getAs<FunctionType>());
assert(Proto && "Methods without a prototype cannot be overloaded")((void)0);
assert(!isa<CXXConstructorDecl>(Method) &&((void)0)
       "Use AddOverloadCandidate for constructors")((void)0);

if (!CandidateSet.isNewCandidate(Method, PO))
  return;

// C++11 [class.copy]p23: [DR1402]
//   A defaulted move assignment operator that is defined as deleted is
//   ignored by overload resolution.
if (Method->isDefaulted() && Method->isDeleted() &&
    Method->isMoveAssignmentOperator())
  return;

// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

// Add this candidate
OverloadCandidate &Candidate =
    CandidateSet.addCandidate(Args.size() + 1, EarlyConversions);
Candidate.FoundDecl = FoundDecl;
Candidate.Function = Method;
Candidate.RewriteKind =
    CandidateSet.getRewriteInfo().getRewriteKind(Method, PO);
Candidate.IsSurrogate = false;
Candidate.IgnoreObjectArgument = false;
Candidate.ExplicitCallArguments = Args.size();

unsigned NumParams = Proto->getNumParams();

// (C++ 13.3.2p2): A candidate function having fewer than m
// parameters is viable only if it has an ellipsis in its parameter
// list (8.3.5).
if (TooManyArguments(NumParams, Args.size(), PartialOverloading) &&
    !Proto->isVariadic()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_many_arguments;
  return;
}

// (C++ 13.3.2p2): A candidate function having more than m parameters
// is viable only if the (m+1)st parameter has a default argument
// (8.3.6). For the purposes of overload resolution, the
// parameter list is truncated on the right, so that there are
// exactly m parameters.
unsigned MinRequiredArgs = Method->getMinRequiredArguments();
if (Args.size() < MinRequiredArgs && !PartialOverloading) {
  // Not enough arguments.
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_few_arguments;
  return;
}

Candidate.Viable = true;

if (Method->isStatic() || ObjectType.isNull())
  // The implicit object argument is ignored.
  Candidate.IgnoreObjectArgument = true;
else {
  unsigned ConvIdx = PO == OverloadCandidateParamOrder::Reversed ? 1 : 0;
  // Determine the implicit conversion sequence for the object
  // parameter.
  Candidate.Conversions[ConvIdx] = TryObjectArgumentInitialization(
      *this, CandidateSet.getLocation(), ObjectType, ObjectClassification,
      Method, ActingContext);
  if (Candidate.Conversions[ConvIdx].isBad()) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_bad_conversion;
    return;
  }
}

// (CUDA B.1): Check for invalid calls between targets.
if (getLangOpts().CUDA)
  if (const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext))
    if (!IsAllowedCUDACall(Caller, Method)) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_bad_target;
      return;
    }

if (Method->getTrailingRequiresClause()) {
  ConstraintSatisfaction Satisfaction;
  if (CheckFunctionConstraints(Method, Satisfaction) ||
      !Satisfaction.IsSatisfied) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_constraints_not_satisfied;
    return;
  }
}

// Determine the implicit conversion sequences for each of the
// arguments.
for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
  unsigned ConvIdx =
      PO == OverloadCandidateParamOrder::Reversed ? 0 : (ArgIdx + 1);
  if (Candidate.Conversions[ConvIdx].isInitialized()) {
    // We already formed a conversion sequence for this parameter during
    // template argument deduction.
  } else if (ArgIdx < NumParams) {
    // (C++ 13.3.2p3): for F to be a viable function, there shall
    // exist for each argument an implicit conversion sequence
    // (13.3.3.1) that converts that argument to the corresponding
    // parameter of F.
    QualType ParamType = Proto->getParamType(ArgIdx);
    Candidate.Conversions[ConvIdx]
      = TryCopyInitialization(*this, Args[ArgIdx], ParamType,
                              SuppressUserConversions,
                              /*InOverloadResolution=*/true,
                              /*AllowObjCWritebackConversion=*/
                                getLangOpts().ObjCAutoRefCount);
    if (Candidate.Conversions[ConvIdx].isBad()) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_bad_conversion;
      return;
    }
  } else {
    // (C++ 13.3.2p2): For the purposes of overload resolution, any
    // argument for which there is no corresponding parameter is
    // considered to "match the ellipsis" (C+ 13.3.3.1.3).
    Candidate.Conversions[ConvIdx].setEllipsis();
  }
}

if (EnableIfAttr *FailedAttr =
        CheckEnableIf(Method, CandidateSet.getLocation(), Args, true)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_enable_if;
  Candidate.DeductionFailure.Data = FailedAttr;
  return;
}

if (Method->isMultiVersion() && Method->hasAttr<TargetAttr>() &&
    !Method->getAttr<TargetAttr>()->isDefaultVersion()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_non_default_multiversion_function;
}
6993}

6995/// Add a C++ member function template as a candidate to the candidate
6996/// set, using template argument deduction to produce an appropriate member
6997/// function template specialization.
6998void Sema::AddMethodTemplateCandidate(
  FunctionTemplateDecl *MethodTmpl, DeclAccessPair FoundDecl,
  CXXRecordDecl *ActingContext,
  TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ObjectType,
  Expr::Classification ObjectClassification, ArrayRef<Expr *> Args,
  OverloadCandidateSet &CandidateSet, bool SuppressUserConversions,
  bool PartialOverloading, OverloadCandidateParamOrder PO) {
if (!CandidateSet.isNewCandidate(MethodTmpl, PO))
  return;

// C++ [over.match.funcs]p7:
//   In each case where a candidate is a function template, candidate
//   function template specializations are generated using template argument
//   deduction (14.8.3, 14.8.2). Those candidates are then handled as
//   candidate functions in the usual way.113) A given name can refer to one
//   or more function templates and also to a set of overloaded non-template
//   functions. In such a case, the candidate functions generated from each
//   function template are combined with the set of non-template candidate
//   functions.
TemplateDeductionInfo Info(CandidateSet.getLocation());
FunctionDecl *Specialization = nullptr;
ConversionSequenceList Conversions;
if (TemplateDeductionResult Result = DeduceTemplateArguments(
        MethodTmpl, ExplicitTemplateArgs, Args, Specialization, Info,
        PartialOverloading, [&](ArrayRef<QualType> ParamTypes) {
          return CheckNonDependentConversions(
              MethodTmpl, ParamTypes, Args, CandidateSet, Conversions,
              SuppressUserConversions, ActingContext, ObjectType,
              ObjectClassification, PO);
        })) {
  OverloadCandidate &Candidate =
      CandidateSet.addCandidate(Conversions.size(), Conversions);
  Candidate.FoundDecl = FoundDecl;
  Candidate.Function = MethodTmpl->getTemplatedDecl();
  Candidate.Viable = false;
  Candidate.RewriteKind =
    CandidateSet.getRewriteInfo().getRewriteKind(Candidate.Function, PO);
  Candidate.IsSurrogate = false;
  Candidate.IgnoreObjectArgument =
      cast<CXXMethodDecl>(Candidate.Function)->isStatic() ||
      ObjectType.isNull();
  Candidate.ExplicitCallArguments = Args.size();
  if (Result == TDK_NonDependentConversionFailure)
    Candidate.FailureKind = ovl_fail_bad_conversion;
  else {
    Candidate.FailureKind = ovl_fail_bad_deduction;
    Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
                                                          Info);
  }
  return;
}

// Add the function template specialization produced by template argument
// deduction as a candidate.
assert(Specialization && "Missing member function template specialization?")((void)0);
assert(isa<CXXMethodDecl>(Specialization) &&((void)0)
       "Specialization is not a member function?")((void)0);
AddMethodCandidate(cast<CXXMethodDecl>(Specialization), FoundDecl,
                   ActingContext, ObjectType, ObjectClassification, Args,
                   CandidateSet, SuppressUserConversions, PartialOverloading,
                   Conversions, PO);
7059}

7061/// Determine whether a given function template has a simple explicit specifier
7062/// or a non-value-dependent explicit-specification that evaluates to true.
7063static bool isNonDependentlyExplicit(FunctionTemplateDecl *FTD) {
return ExplicitSpecifier::getFromDecl(FTD->getTemplatedDecl()).isExplicit();
7065}

7067/// Add a C++ function template specialization as a candidate
7068/// in the candidate set, using template argument deduction to produce
7069/// an appropriate function template specialization.
7070void Sema::AddTemplateOverloadCandidate(
  FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
  TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
  OverloadCandidateSet &CandidateSet, bool SuppressUserConversions,
  bool PartialOverloading, bool AllowExplicit, ADLCallKind IsADLCandidate,
  OverloadCandidateParamOrder PO) {
if (!CandidateSet.isNewCandidate(FunctionTemplate, PO))
  return;

// If the function template has a non-dependent explicit specification,
// exclude it now if appropriate; we are not permitted to perform deduction
// and substitution in this case.
if (!AllowExplicit && isNonDependentlyExplicit(FunctionTemplate)) {
  OverloadCandidate &Candidate = CandidateSet.addCandidate();
  Candidate.FoundDecl = FoundDecl;
  Candidate.Function = FunctionTemplate->getTemplatedDecl();
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_explicit;
  return;
}

// C++ [over.match.funcs]p7:
//   In each case where a candidate is a function template, candidate
//   function template specializations are generated using template argument
//   deduction (14.8.3, 14.8.2). Those candidates are then handled as
//   candidate functions in the usual way.113) A given name can refer to one
//   or more function templates and also to a set of overloaded non-template
//   functions. In such a case, the candidate functions generated from each
//   function template are combined with the set of non-template candidate
//   functions.
TemplateDeductionInfo Info(CandidateSet.getLocation());
FunctionDecl *Specialization = nullptr;
ConversionSequenceList Conversions;
if (TemplateDeductionResult Result = DeduceTemplateArguments(
        FunctionTemplate, ExplicitTemplateArgs, Args, Specialization, Info,
        PartialOverloading, [&](ArrayRef<QualType> ParamTypes) {
          return CheckNonDependentConversions(
              FunctionTemplate, ParamTypes, Args, CandidateSet, Conversions,
              SuppressUserConversions, nullptr, QualType(), {}, PO);
        })) {
  OverloadCandidate &Candidate =
      CandidateSet.addCandidate(Conversions.size(), Conversions);
  Candidate.FoundDecl = FoundDecl;
  Candidate.Function = FunctionTemplate->getTemplatedDecl();
  Candidate.Viable = false;
  Candidate.RewriteKind =
    CandidateSet.getRewriteInfo().getRewriteKind(Candidate.Function, PO);
  Candidate.IsSurrogate = false;
  Candidate.IsADLCandidate = IsADLCandidate;
  // Ignore the object argument if there is one, since we don't have an object
  // type.
  Candidate.IgnoreObjectArgument =
      isa<CXXMethodDecl>(Candidate.Function) &&
      !isa<CXXConstructorDecl>(Candidate.Function);
  Candidate.ExplicitCallArguments = Args.size();
  if (Result == TDK_NonDependentConversionFailure)
    Candidate.FailureKind = ovl_fail_bad_conversion;
  else {
    Candidate.FailureKind = ovl_fail_bad_deduction;
    Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
                                                          Info);
  }
  return;
}

// Add the function template specialization produced by template argument
// deduction as a candidate.
assert(Specialization && "Missing function template specialization?")((void)0);
AddOverloadCandidate(
    Specialization, FoundDecl, Args, CandidateSet, SuppressUserConversions,
    PartialOverloading, AllowExplicit,
    /*AllowExplicitConversions*/ false, IsADLCandidate, Conversions, PO);
7142}

7144/// Check that implicit conversion sequences can be formed for each argument
7145/// whose corresponding parameter has a non-dependent type, per DR1391's
7146/// [temp.deduct.call]p10.
7147bool Sema::CheckNonDependentConversions(
  FunctionTemplateDecl *FunctionTemplate, ArrayRef<QualType> ParamTypes,
  ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet,
  ConversionSequenceList &Conversions, bool SuppressUserConversions,
  CXXRecordDecl *ActingContext, QualType ObjectType,
  Expr::Classification ObjectClassification, OverloadCandidateParamOrder PO) {
// FIXME: The cases in which we allow explicit conversions for constructor
// arguments never consider calling a constructor template. It's not clear
// that is correct.
const bool AllowExplicit = false;

auto *FD = FunctionTemplate->getTemplatedDecl();
auto *Method = dyn_cast<CXXMethodDecl>(FD);
bool HasThisConversion = Method && !isa<CXXConstructorDecl>(Method);
unsigned ThisConversions = HasThisConversion ? 1 : 0;

Conversions =
    CandidateSet.allocateConversionSequences(ThisConversions + Args.size());

// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

// For a method call, check the 'this' conversion here too. DR1391 doesn't
// require that, but this check should never result in a hard error, and
// overload resolution is permitted to sidestep instantiations.
if (HasThisConversion && !cast<CXXMethodDecl>(FD)->isStatic() &&
    !ObjectType.isNull()) {
  unsigned ConvIdx = PO == OverloadCandidateParamOrder::Reversed ? 1 : 0;
  Conversions[ConvIdx] = TryObjectArgumentInitialization(
      *this, CandidateSet.getLocation(), ObjectType, ObjectClassification,
      Method, ActingContext);
  if (Conversions[ConvIdx].isBad())
    return true;
}

for (unsigned I = 0, N = std::min(ParamTypes.size(), Args.size()); I != N;
     ++I) {
  QualType ParamType = ParamTypes[I];
  if (!ParamType->isDependentType()) {
    unsigned ConvIdx = PO == OverloadCandidateParamOrder::Reversed
                           ? 0
                           : (ThisConversions + I);
    Conversions[ConvIdx]
      = TryCopyInitialization(*this, Args[I], ParamType,
                              SuppressUserConversions,
                              /*InOverloadResolution=*/true,
                              /*AllowObjCWritebackConversion=*/
                                getLangOpts().ObjCAutoRefCount,
                              AllowExplicit);
    if (Conversions[ConvIdx].isBad())
      return true;
  }
}

return false;
7203}

7205/// Determine whether this is an allowable conversion from the result
7206/// of an explicit conversion operator to the expected type, per C++
7207/// [over.match.conv]p1 and [over.match.ref]p1.
7208///
7209/// \param ConvType The return type of the conversion function.
7210///
7211/// \param ToType The type we are converting to.
7212///
7213/// \param AllowObjCPointerConversion Allow a conversion from one
7214/// Objective-C pointer to another.
7215///
7216/// \returns true if the conversion is allowable, false otherwise.
7217static bool isAllowableExplicitConversion(Sema &S,
                                        QualType ConvType, QualType ToType,
                                        bool AllowObjCPointerConversion) {
QualType ToNonRefType = ToType.getNonReferenceType();

// Easy case: the types are the same.
if (S.Context.hasSameUnqualifiedType(ConvType, ToNonRefType))
  return true;

// Allow qualification conversions.
bool ObjCLifetimeConversion;
if (S.IsQualificationConversion(ConvType, ToNonRefType, /*CStyle*/false,
                                ObjCLifetimeConversion))
  return true;

// If we're not allowed to consider Objective-C pointer conversions,
// we're done.
if (!AllowObjCPointerConversion)
  return false;

// Is this an Objective-C pointer conversion?
bool IncompatibleObjC = false;
QualType ConvertedType;
return S.isObjCPointerConversion(ConvType, ToNonRefType, ConvertedType,
                                 IncompatibleObjC);
7242}

7244/// AddConversionCandidate - Add a C++ conversion function as a
7245/// candidate in the candidate set (C++ [over.match.conv],
7246/// C++ [over.match.copy]). From is the expression we're converting from,
7247/// and ToType is the type that we're eventually trying to convert to
7248/// (which may or may not be the same type as the type that the
7249/// conversion function produces).
7250void Sema::AddConversionCandidate(
  CXXConversionDecl *Conversion, DeclAccessPair FoundDecl,
  CXXRecordDecl *ActingContext, Expr *From, QualType ToType,
  OverloadCandidateSet &CandidateSet, bool AllowObjCConversionOnExplicit,
  bool AllowExplicit, bool AllowResultConversion) {
assert(!Conversion->getDescribedFunctionTemplate() &&((void)0)
       "Conversion function templates use AddTemplateConversionCandidate")((void)0);
QualType ConvType = Conversion->getConversionType().getNonReferenceType();
if (!CandidateSet.isNewCandidate(Conversion))
  return;

// If the conversion function has an undeduced return type, trigger its
// deduction now.
if (getLangOpts().CPlusPlus14 && ConvType->isUndeducedType()) {
  if (DeduceReturnType(Conversion, From->getExprLoc()))
    return;
  ConvType = Conversion->getConversionType().getNonReferenceType();
}

// If we don't allow any conversion of the result type, ignore conversion
// functions that don't convert to exactly (possibly cv-qualified) T.
if (!AllowResultConversion &&
    !Context.hasSameUnqualifiedType(Conversion->getConversionType(), ToType))
  return;

// Per C++ [over.match.conv]p1, [over.match.ref]p1, an explicit conversion
// operator is only a candidate if its return type is the target type or
// can be converted to the target type with a qualification conversion.
//
// FIXME: Include such functions in the candidate list and explain why we
// can't select them.
if (Conversion->isExplicit() &&
    !isAllowableExplicitConversion(*this, ConvType, ToType,
                                   AllowObjCConversionOnExplicit))
  return;

// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

// Add this candidate
OverloadCandidate &Candidate = CandidateSet.addCandidate(1);
Candidate.FoundDecl = FoundDecl;
Candidate.Function = Conversion;
Candidate.IsSurrogate = false;
Candidate.IgnoreObjectArgument = false;
Candidate.FinalConversion.setAsIdentityConversion();
Candidate.FinalConversion.setFromType(ConvType);
Candidate.FinalConversion.setAllToTypes(ToType);
Candidate.Viable = true;
Candidate.ExplicitCallArguments = 1;

// Explicit functions are not actually candidates at all if we're not
// allowing them in this context, but keep them around so we can point
// to them in diagnostics.
if (!AllowExplicit && Conversion->isExplicit()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_explicit;
  return;
}

// C++ [over.match.funcs]p4:
//   For conversion functions, the function is considered to be a member of
//   the class of the implicit implied object argument for the purpose of
//   defining the type of the implicit object parameter.
//
// Determine the implicit conversion sequence for the implicit
// object parameter.
QualType ImplicitParamType = From->getType();
if (const PointerType *FromPtrType = ImplicitParamType->getAs<PointerType>())
  ImplicitParamType = FromPtrType->getPointeeType();
CXXRecordDecl *ConversionContext
  = cast<CXXRecordDecl>(ImplicitParamType->castAs<RecordType>()->getDecl());

Candidate.Conversions[0] = TryObjectArgumentInitialization(
    *this, CandidateSet.getLocation(), From->getType(),
    From->Classify(Context), Conversion, ConversionContext);

if (Candidate.Conversions[0].isBad()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_bad_conversion;
  return;
}

if (Conversion->getTrailingRequiresClause()) {
  ConstraintSatisfaction Satisfaction;
  if (CheckFunctionConstraints(Conversion, Satisfaction) ||
      !Satisfaction.IsSatisfied) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_constraints_not_satisfied;
    return;
  }
}

// We won't go through a user-defined type conversion function to convert a
// derived to base as such conversions are given Conversion Rank. They only
// go through a copy constructor. 13.3.3.1.2-p4 [over.ics.user]
QualType FromCanon
  = Context.getCanonicalType(From->getType().getUnqualifiedType());
QualType ToCanon = Context.getCanonicalType(ToType).getUnqualifiedType();
if (FromCanon == ToCanon ||
    IsDerivedFrom(CandidateSet.getLocation(), FromCanon, ToCanon)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_trivial_conversion;
  return;
}

// To determine what the conversion from the result of calling the
// conversion function to the type we're eventually trying to
// convert to (ToType), we need to synthesize a call to the
// conversion function and attempt copy initialization from it. This
// makes sure that we get the right semantics with respect to
// lvalues/rvalues and the type. Fortunately, we can allocate this
// call on the stack and we don't need its arguments to be
// well-formed.
DeclRefExpr ConversionRef(Context, Conversion, false, Conversion->getType(),
                          VK_LValue, From->getBeginLoc());
ImplicitCastExpr ConversionFn(ImplicitCastExpr::OnStack,
                              Context.getPointerType(Conversion->getType()),
                              CK_FunctionToPointerDecay, &ConversionRef,
                              VK_PRValue, FPOptionsOverride());

QualType ConversionType = Conversion->getConversionType();
if (!isCompleteType(From->getBeginLoc(), ConversionType)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_bad_final_conversion;
  return;
}

ExprValueKind VK = Expr::getValueKindForType(ConversionType);

// Note that it is safe to allocate CallExpr on the stack here because
// there are 0 arguments (i.e., nothing is allocated using ASTContext's
// allocator).
QualType CallResultType = ConversionType.getNonLValueExprType(Context);

alignas(CallExpr) char Buffer[sizeof(CallExpr) + sizeof(Stmt *)];
CallExpr *TheTemporaryCall = CallExpr::CreateTemporary(
    Buffer, &ConversionFn, CallResultType, VK, From->getBeginLoc());

ImplicitConversionSequence ICS =
    TryCopyInitialization(*this, TheTemporaryCall, ToType,
                          /*SuppressUserConversions=*/true,
                          /*InOverloadResolution=*/false,
                          /*AllowObjCWritebackConversion=*/false);

switch (ICS.getKind()) {
case ImplicitConversionSequence::StandardConversion:
  Candidate.FinalConversion = ICS.Standard;

  // C++ [over.ics.user]p3:
  //   If the user-defined conversion is specified by a specialization of a
  //   conversion function template, the second standard conversion sequence
  //   shall have exact match rank.
  if (Conversion->getPrimaryTemplate() &&
      GetConversionRank(ICS.Standard.Second) != ICR_Exact_Match) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_final_conversion_not_exact;
    return;
  }

  // C++0x [dcl.init.ref]p5:
  //    In the second case, if the reference is an rvalue reference and
  //    the second standard conversion sequence of the user-defined
  //    conversion sequence includes an lvalue-to-rvalue conversion, the
  //    program is ill-formed.
  if (ToType->isRValueReferenceType() &&
      ICS.Standard.First == ICK_Lvalue_To_Rvalue) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_bad_final_conversion;
    return;
  }
  break;

case ImplicitConversionSequence::BadConversion:
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_bad_final_conversion;
  return;

default:
  llvm_unreachable(__builtin_unreachable()
         "Can only end up with a standard conversion sequence or failure")__builtin_unreachable();
}

if (EnableIfAttr *FailedAttr =
        CheckEnableIf(Conversion, CandidateSet.getLocation(), None)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_enable_if;
  Candidate.DeductionFailure.Data = FailedAttr;
  return;
}

if (Conversion->isMultiVersion() && Conversion->hasAttr<TargetAttr>() &&
    !Conversion->getAttr<TargetAttr>()->isDefaultVersion()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_non_default_multiversion_function;
}
7447}

7449/// Adds a conversion function template specialization
7450/// candidate to the overload set, using template argument deduction
7451/// to deduce the template arguments of the conversion function
7452/// template from the type that we are converting to (C++
7453/// [temp.deduct.conv]).
7454void Sema::AddTemplateConversionCandidate(
  FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
  CXXRecordDecl *ActingDC, Expr *From, QualType ToType,
  OverloadCandidateSet &CandidateSet, bool AllowObjCConversionOnExplicit,
  bool AllowExplicit, bool AllowResultConversion) {
assert(isa<CXXConversionDecl>(FunctionTemplate->getTemplatedDecl()) &&((void)0)
       "Only conversion function templates permitted here")((void)0);

if (!CandidateSet.isNewCandidate(FunctionTemplate))
  return;

// If the function template has a non-dependent explicit specification,
// exclude it now if appropriate; we are not permitted to perform deduction
// and substitution in this case.
if (!AllowExplicit && isNonDependentlyExplicit(FunctionTemplate)) {
  OverloadCandidate &Candidate = CandidateSet.addCandidate();
  Candidate.FoundDecl = FoundDecl;
  Candidate.Function = FunctionTemplate->getTemplatedDecl();
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_explicit;
  return;
}

TemplateDeductionInfo Info(CandidateSet.getLocation());
CXXConversionDecl *Specialization = nullptr;
if (TemplateDeductionResult Result
      = DeduceTemplateArguments(FunctionTemplate, ToType,
                                Specialization, Info)) {
  OverloadCandidate &Candidate = CandidateSet.addCandidate();
  Candidate.FoundDecl = FoundDecl;
  Candidate.Function = FunctionTemplate->getTemplatedDecl();
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_bad_deduction;
  Candidate.IsSurrogate = false;
  Candidate.IgnoreObjectArgument = false;
  Candidate.ExplicitCallArguments = 1;
  Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
                                                        Info);
  return;
}

// Add the conversion function template specialization produced by
// template argument deduction as a candidate.
assert(Specialization && "Missing function template specialization?")((void)0);
AddConversionCandidate(Specialization, FoundDecl, ActingDC, From, ToType,
                       CandidateSet, AllowObjCConversionOnExplicit,
                       AllowExplicit, AllowResultConversion);
7501}

7503/// AddSurrogateCandidate - Adds a "surrogate" candidate function that
7504/// converts the given @c Object to a function pointer via the
7505/// conversion function @c Conversion, and then attempts to call it
7506/// with the given arguments (C++ [over.call.object]p2-4). Proto is
7507/// the type of function that we'll eventually be calling.
7508void Sema::AddSurrogateCandidate(CXXConversionDecl *Conversion,
                               DeclAccessPair FoundDecl,
                               CXXRecordDecl *ActingContext,
                               const FunctionProtoType *Proto,
                               Expr *Object,
                               ArrayRef<Expr *> Args,
                               OverloadCandidateSet& CandidateSet) {
if (!CandidateSet.isNewCandidate(Conversion))
  return;

// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size() + 1);
Candidate.FoundDecl = FoundDecl;
Candidate.Function = nullptr;
Candidate.Surrogate = Conversion;
Candidate.Viable = true;
Candidate.IsSurrogate = true;
Candidate.IgnoreObjectArgument = false;
Candidate.ExplicitCallArguments = Args.size();

// Determine the implicit conversion sequence for the implicit
// object parameter.
ImplicitConversionSequence ObjectInit = TryObjectArgumentInitialization(
    *this, CandidateSet.getLocation(), Object->getType(),
    Object->Classify(Context), Conversion, ActingContext);
if (ObjectInit.isBad()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_bad_conversion;
  Candidate.Conversions[0] = ObjectInit;
  return;
}

// The first conversion is actually a user-defined conversion whose
// first conversion is ObjectInit's standard conversion (which is
// effectively a reference binding). Record it as such.
Candidate.Conversions[0].setUserDefined();
Candidate.Conversions[0].UserDefined.Before = ObjectInit.Standard;
Candidate.Conversions[0].UserDefined.EllipsisConversion = false;
Candidate.Conversions[0].UserDefined.HadMultipleCandidates = false;
Candidate.Conversions[0].UserDefined.ConversionFunction = Conversion;
Candidate.Conversions[0].UserDefined.FoundConversionFunction = FoundDecl;
Candidate.Conversions[0].UserDefined.After
  = Candidate.Conversions[0].UserDefined.Before;
Candidate.Conversions[0].UserDefined.After.setAsIdentityConversion();

// Find the
unsigned NumParams = Proto->getNumParams();

// (C++ 13.3.2p2): A candidate function having fewer than m
// parameters is viable only if it has an ellipsis in its parameter
// list (8.3.5).
if (Args.size() > NumParams && !Proto->isVariadic()) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_many_arguments;
  return;
}

// Function types don't have any default arguments, so just check if
// we have enough arguments.
if (Args.size() < NumParams) {
  // Not enough arguments.
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_too_few_arguments;
  return;
}

// Determine the implicit conversion sequences for each of the
// arguments.
for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
  if (ArgIdx < NumParams) {
    // (C++ 13.3.2p3): for F to be a viable function, there shall
    // exist for each argument an implicit conversion sequence
    // (13.3.3.1) that converts that argument to the corresponding
    // parameter of F.
    QualType ParamType = Proto->getParamType(ArgIdx);
    Candidate.Conversions[ArgIdx + 1]
      = TryCopyInitialization(*this, Args[ArgIdx], ParamType,
                              /*SuppressUserConversions=*/false,
                              /*InOverloadResolution=*/false,
                              /*AllowObjCWritebackConversion=*/
                                getLangOpts().ObjCAutoRefCount);
    if (Candidate.Conversions[ArgIdx + 1].isBad()) {
      Candidate.Viable = false;
      Candidate.FailureKind = ovl_fail_bad_conversion;
      return;
    }
  } else {
    // (C++ 13.3.2p2): For the purposes of overload resolution, any
    // argument for which there is no corresponding parameter is
    // considered to ""match the ellipsis" (C+ 13.3.3.1.3).
    Candidate.Conversions[ArgIdx + 1].setEllipsis();
  }
}

if (EnableIfAttr *FailedAttr =
        CheckEnableIf(Conversion, CandidateSet.getLocation(), None)) {
  Candidate.Viable = false;
  Candidate.FailureKind = ovl_fail_enable_if;
  Candidate.DeductionFailure.Data = FailedAttr;
  return;
}
7612}

7614/// Add all of the non-member operator function declarations in the given
7615/// function set to the overload candidate set.
7616void Sema::AddNonMemberOperatorCandidates(
  const UnresolvedSetImpl &Fns, ArrayRef<Expr *> Args,
  OverloadCandidateSet &CandidateSet,
  TemplateArgumentListInfo *ExplicitTemplateArgs) {
for (UnresolvedSetIterator F = Fns.begin(), E = Fns.end(); F != E; ++F) {
  NamedDecl *D = F.getDecl()->getUnderlyingDecl();
  ArrayRef<Expr *> FunctionArgs = Args;

  FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D);
  FunctionDecl *FD =
      FunTmpl ? FunTmpl->getTemplatedDecl() : cast<FunctionDecl>(D);

  // Don't consider rewritten functions if we're not rewriting.
  if (!CandidateSet.getRewriteInfo().isAcceptableCandidate(FD))
    continue;

  assert(!isa<CXXMethodDecl>(FD) &&((void)0)
         "unqualified operator lookup found a member function")((void)0);

  if (FunTmpl) {
    AddTemplateOverloadCandidate(FunTmpl, F.getPair(), ExplicitTemplateArgs,
                                 FunctionArgs, CandidateSet);
    if (CandidateSet.getRewriteInfo().shouldAddReversed(Context, FD))
      AddTemplateOverloadCandidate(
          FunTmpl, F.getPair(), ExplicitTemplateArgs,
          {FunctionArgs[1], FunctionArgs[0]}, CandidateSet, false, false,
          true, ADLCallKind::NotADL, OverloadCandidateParamOrder::Reversed);
  } else {
    if (ExplicitTemplateArgs)
      continue;
    AddOverloadCandidate(FD, F.getPair(), FunctionArgs, CandidateSet);
    if (CandidateSet.getRewriteInfo().shouldAddReversed(Context, FD))
      AddOverloadCandidate(FD, F.getPair(),
                           {FunctionArgs[1], FunctionArgs[0]}, CandidateSet,
                           false, false, true, false, ADLCallKind::NotADL,
                           None, OverloadCandidateParamOrder::Reversed);
  }
}
7654}

7656/// Add overload candidates for overloaded operators that are
7657/// member functions.
7658///
7659/// Add the overloaded operator candidates that are member functions
7660/// for the operator Op that was used in an operator expression such
7661/// as "x Op y". , Args/NumArgs provides the operator arguments, and
7662/// CandidateSet will store the added overload candidates. (C++
7663/// [over.match.oper]).
7664void Sema::AddMemberOperatorCandidates(OverloadedOperatorKind Op,
                                     SourceLocation OpLoc,
                                     ArrayRef<Expr *> Args,
                                     OverloadCandidateSet &CandidateSet,
                                     OverloadCandidateParamOrder PO) {
DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);

// C++ [over.match.oper]p3:
//   For a unary operator @ with an operand of a type whose
//   cv-unqualified version is T1, and for a binary operator @ with
//   a left operand of a type whose cv-unqualified version is T1 and
//   a right operand of a type whose cv-unqualified version is T2,
//   three sets of candidate functions, designated member
//   candidates, non-member candidates and built-in candidates, are
//   constructed as follows:
QualType T1 = Args[0]->getType();

//     -- If T1 is a complete class type or a class currently being
//        defined, the set of member candidates is the result of the
//        qualified lookup of T1::operator@ (13.3.1.1.1); otherwise,
//        the set of member candidates is empty.
if (const RecordType *T1Rec = T1->getAs<RecordType>()) {
  // Complete the type if it can be completed.
  if (!isCompleteType(OpLoc, T1) && !T1Rec->isBeingDefined())
    return;
  // If the type is neither complete nor being defined, bail out now.
  if (!T1Rec->getDecl()->getDefinition())
    return;

  LookupResult Operators(*this, OpName, OpLoc, LookupOrdinaryName);
  LookupQualifiedName(Operators, T1Rec->getDecl());
  Operators.suppressDiagnostics();

  for (LookupResult::iterator Oper = Operators.begin(),
                           OperEnd = Operators.end();
       Oper != OperEnd;
       ++Oper)
    AddMethodCandidate(Oper.getPair(), Args[0]->getType(),
                       Args[0]->Classify(Context), Args.slice(1),
                       CandidateSet, /*SuppressUserConversion=*/false, PO);
}
7705}

7707/// AddBuiltinCandidate - Add a candidate for a built-in
7708/// operator. ResultTy and ParamTys are the result and parameter types
7709/// of the built-in candidate, respectively. Args and NumArgs are the
7710/// arguments being passed to the candidate. IsAssignmentOperator
7711/// should be true when this built-in candidate is an assignment
7712/// operator. NumContextualBoolArguments is the number of arguments
7713/// (at the beginning of the argument list) that will be contextually
7714/// converted to bool.
7715void Sema::AddBuiltinCandidate(QualType *ParamTys, ArrayRef<Expr *> Args,
                             OverloadCandidateSet& CandidateSet,
                             bool IsAssignmentOperator,
                             unsigned NumContextualBoolArguments) {
// Overload resolution is always an unevaluated context.
EnterExpressionEvaluationContext Unevaluated(
    *this, Sema::ExpressionEvaluationContext::Unevaluated);

// Add this candidate
OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size());
Candidate.FoundDecl = DeclAccessPair::make(nullptr, AS_none);
Candidate.Function = nullptr;
Candidate.IsSurrogate = false;
Candidate.IgnoreObjectArgument = false;
std::copy(ParamTys, ParamTys + Args.size(), Candidate.BuiltinParamTypes);

// Determine the implicit conversion sequences for each of the
// arguments.
Candidate.Viable = true;
Candidate.ExplicitCallArguments = Args.size();
for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
  // C++ [over.match.oper]p4:
  //   For the built-in assignment operators, conversions of the
  //   left operand are restricted as follows:
  //     -- no temporaries are introduced to hold the left operand, and
  //     -- no user-defined conversions are applied to the left
  //        operand to achieve a type match with the left-most
  //        parameter of a built-in candidate.
  //
  // We block these conversions by turning off user-defined
  // conversions, since that is the only way that initialization of
  // a reference to a non-class type can occur from something that
  // is not of the same type.
  if (ArgIdx < NumContextualBoolArguments) {
    assert(ParamTys[ArgIdx] == Context.BoolTy &&((void)0)
           "Contextual conversion to bool requires bool type")((void)0);
    Candidate.Conversions[ArgIdx]
      = TryContextuallyConvertToBool(*this, Args[ArgIdx]);
  } else {
    Candidate.Conversions[ArgIdx]
      = TryCopyInitialization(*this, Args[ArgIdx], ParamTys[ArgIdx],
                              ArgIdx == 0 && IsAssignmentOperator,
                              /*InOverloadResolution=*/false,
                              /*AllowObjCWritebackConversion=*/
                                getLangOpts().ObjCAutoRefCount);
  }
  if (Candidate.Conversions[ArgIdx].isBad()) {
    Candidate.Viable = false;
    Candidate.FailureKind = ovl_fail_bad_conversion;
    break;
  }
}
7767}

7769namespace {

7771/// BuiltinCandidateTypeSet - A set of types that will be used for the
7772/// candidate operator functions for built-in operators (C++
7773/// [over.built]). The types are separated into pointer types and
7774/// enumeration types.
7775class BuiltinCandidateTypeSet  {
/// TypeSet - A set of types.
typedef llvm::SetVector<QualType, SmallVector<QualType, 8>,
                        llvm::SmallPtrSet<QualType, 8>> TypeSet;

/// PointerTypes - The set of pointer types that will be used in the
/// built-in candidates.
TypeSet PointerTypes;

/// MemberPointerTypes - The set of member pointer types that will be
/// used in the built-in candidates.
TypeSet MemberPointerTypes;

/// EnumerationTypes - The set of enumeration types that will be
/// used in the built-in candidates.
TypeSet EnumerationTypes;

/// The set of vector types that will be used in the built-in
/// candidates.
TypeSet VectorTypes;

/// The set of matrix types that will be used in the built-in
/// candidates.
TypeSet MatrixTypes;

/// A flag indicating non-record types are viable candidates
bool HasNonRecordTypes;

/// A flag indicating whether either arithmetic or enumeration types
/// were present in the candidate set.
bool HasArithmeticOrEnumeralTypes;

/// A flag indicating whether the nullptr type was present in the
/// candidate set.
bool HasNullPtrType;

/// Sema - The semantic analysis instance where we are building the
/// candidate type set.
Sema &SemaRef;

/// Context - The AST context in which we will build the type sets.
ASTContext &Context;

bool AddPointerWithMoreQualifiedTypeVariants(QualType Ty,
                                             const Qualifiers &VisibleQuals);
bool AddMemberPointerWithMoreQualifiedTypeVariants(QualType Ty);

7822public:
/// iterator - Iterates through the types that are part of the set.
typedef TypeSet::iterator iterator;

BuiltinCandidateTypeSet(Sema &SemaRef)
  : HasNonRecordTypes(false),
    HasArithmeticOrEnumeralTypes(false),
    HasNullPtrType(false),
    SemaRef(SemaRef),
    Context(SemaRef.Context) { }

void AddTypesConvertedFrom(QualType Ty,
                           SourceLocation Loc,
                           bool AllowUserConversions,
                           bool AllowExplicitConversions,
                           const Qualifiers &VisibleTypeConversionsQuals);

llvm::iterator_range<iterator> pointer_types() { return PointerTypes; }
llvm::iterator_range<iterator> member_pointer_types() {
  return MemberPointerTypes;
}
llvm::iterator_range<iterator> enumeration_types() {
  return EnumerationTypes;
}
llvm::iterator_range<iterator> vector_types() { return VectorTypes; }
llvm::iterator_range<iterator> matrix_types() { return MatrixTypes; }

bool containsMatrixType(QualType Ty) const { return MatrixTypes.count(Ty); }
bool hasNonRecordTypes() { return HasNonRecordTypes; }
bool hasArithmeticOrEnumeralTypes() { return HasArithmeticOrEnumeralTypes; }
bool hasNullPtrType() const { return HasNullPtrType; }
7853};

7855} // end anonymous namespace

7857/// AddPointerWithMoreQualifiedTypeVariants - Add the pointer type @p Ty to
7858/// the set of pointer types along with any more-qualified variants of
7859/// that type. For example, if @p Ty is "int const *", this routine
7860/// will add "int const *", "int const volatile *", "int const
7861/// restrict *", and "int const volatile restrict *" to the set of
7862/// pointer types. Returns true if the add of @p Ty itself succeeded,
7863/// false otherwise.
7864///
7865/// FIXME: what to do about extended qualifiers?
7866bool
7867BuiltinCandidateTypeSet::AddPointerWithMoreQualifiedTypeVariants(QualType Ty,
                                           const Qualifiers &VisibleQuals) {

// Insert this type.
if (!PointerTypes.insert(Ty))
  return false;

QualType PointeeTy;
const PointerType *PointerTy = Ty->getAs<PointerType>();
bool buildObjCPtr = false;
if (!PointerTy) {
  const ObjCObjectPointerType *PTy = Ty->castAs<ObjCObjectPointerType>();
  PointeeTy = PTy->getPointeeType();
  buildObjCPtr = true;
} else {
  PointeeTy = PointerTy->getPointeeType();
}

// Don't add qualified variants of arrays. For one, they're not allowed
// (the qualifier would sink to the element type), and for another, the
// only overload situation where it matters is subscript or pointer +- int,
// and those shouldn't have qualifier variants anyway.
if (PointeeTy->isArrayType())
  return true;

unsigned BaseCVR = PointeeTy.getCVRQualifiers();
bool hasVolatile = VisibleQuals.hasVolatile();
bool hasRestrict = VisibleQuals.hasRestrict();

// Iterate through all strict supersets of BaseCVR.
for (unsigned CVR = BaseCVR+1; CVR <= Qualifiers::CVRMask; ++CVR) {
  if ((CVR | BaseCVR) != CVR) continue;
  // Skip over volatile if no volatile found anywhere in the types.
  if ((CVR & Qualifiers::Volatile) && !hasVolatile) continue;

  // Skip over restrict if no restrict found anywhere in the types, or if
  // the type cannot be restrict-qualified.
  if ((CVR & Qualifiers::Restrict) &&
      (!hasRestrict ||
       (!(PointeeTy->isAnyPointerType() || PointeeTy->isReferenceType()))))
    continue;

  // Build qualified pointee type.
  QualType QPointeeTy = Context.getCVRQualifiedType(PointeeTy, CVR);

  // Build qualified pointer type.
  QualType QPointerTy;
  if (!buildObjCPtr)
    QPointerTy = Context.getPointerType(QPointeeTy);
  else
    QPointerTy = Context.getObjCObjectPointerType(QPointeeTy);

  // Insert qualified pointer type.
  PointerTypes.insert(QPointerTy);
}

return true;
7924}

7926/// AddMemberPointerWithMoreQualifiedTypeVariants - Add the pointer type @p Ty
7927/// to the set of pointer types along with any more-qualified variants of
7928/// that type. For example, if @p Ty is "int const *", this routine
7929/// will add "int const *", "int const volatile *", "int const
7930/// restrict *", and "int const volatile restrict *" to the set of
7931/// pointer types. Returns true if the add of @p Ty itself succeeded,
7932/// false otherwise.
7933///
7934/// FIXME: what to do about extended qualifiers?
7935bool
7936BuiltinCandidateTypeSet::AddMemberPointerWithMoreQualifiedTypeVariants(
  QualType Ty) {
// Insert this type.
if (!MemberPointerTypes.insert(Ty))
  return false;

const MemberPointerType *PointerTy = Ty->getAs<MemberPointerType>();
assert(PointerTy && "type was not a member pointer type!")((void)0);

QualType PointeeTy = PointerTy->getPointeeType();
// Don't add qualified variants of arrays. For one, they're not allowed
// (the qualifier would sink to the element type), and for another, the
// only overload situation where it matters is subscript or pointer +- int,
// and those shouldn't have qualifier variants anyway.
if (PointeeTy->isArrayType())
  return true;
const Type *ClassTy = PointerTy->getClass();

// Iterate through all strict supersets of the pointee type's CVR
// qualifiers.
unsigned BaseCVR = PointeeTy.getCVRQualifiers();
for (unsigned CVR = BaseCVR+1; CVR <= Qualifiers::CVRMask; ++CVR) {
  if ((CVR | BaseCVR) != CVR) continue;

  QualType QPointeeTy = Context.getCVRQualifiedType(PointeeTy, CVR);
  MemberPointerTypes.insert(
    Context.getMemberPointerType(QPointeeTy, ClassTy));
}

return true;
7966}

7968/// AddTypesConvertedFrom - Add each of the types to which the type @p
7969/// Ty can be implicit converted to the given set of @p Types. We're
7970/// primarily interested in pointer types and enumeration types. We also
7971/// take member pointer types, for the conditional operator.
7972/// AllowUserConversions is true if we should look at the conversion
7973/// functions of a class type, and AllowExplicitConversions if we
7974/// should also include the explicit conversion functions of a class
7975/// type.
7976void
7977BuiltinCandidateTypeSet::AddTypesConvertedFrom(QualType Ty,
                                             SourceLocation Loc,
                                             bool AllowUserConversions,
                                             bool AllowExplicitConversions,
                                             const Qualifiers &VisibleQuals) {
// Only deal with canonical types.
Ty = Context.getCanonicalType(Ty);

// Look through reference types; they aren't part of the type of an
// expression for the purposes of conversions.
if (const ReferenceType *RefTy = Ty->getAs<ReferenceType>())
  Ty = RefTy->getPointeeType();

// If we're dealing with an array type, decay to the pointer.
if (Ty->isArrayType())
  Ty = SemaRef.Context.getArrayDecayedType(Ty);

// Otherwise, we don't care about qualifiers on the type.
Ty = Ty.getLocalUnqualifiedType();

// Flag if we ever add a non-record type.
const RecordType *TyRec = Ty->getAs<RecordType>();
HasNonRecordTypes = HasNonRecordTypes || !TyRec;

// Flag if we encounter an arithmetic type.
HasArithmeticOrEnumeralTypes =
  HasArithmeticOrEnumeralTypes || Ty->isArithmeticType();

if (Ty->isObjCIdType() || Ty->isObjCClassType())
  PointerTypes.insert(Ty);
else if (Ty->getAs<PointerType>() || Ty->getAs<ObjCObjectPointerType>()) {
  // Insert our type, and its more-qualified variants, into the set
  // of types.
  if (!AddPointerWithMoreQualifiedTypeVariants(Ty, VisibleQuals))
    return;
} else if (Ty->isMemberPointerType()) {
  // Member pointers are far easier, since the pointee can't be converted.
  if (!AddMemberPointerWithMoreQualifiedTypeVariants(Ty))
    return;
} else if (Ty->isEnumeralType()) {
  HasArithmeticOrEnumeralTypes = true;
  EnumerationTypes.insert(Ty);
} else if (Ty->isVectorType()) {
  // We treat vector types as arithmetic types in many contexts as an
  // extension.
  HasArithmeticOrEnumeralTypes = true;
  VectorTypes.insert(Ty);
} else if (Ty->isMatrixType()) {
  // Similar to vector types, we treat vector types as arithmetic types in
  // many contexts as an extension.
  HasArithmeticOrEnumeralTypes = true;
  MatrixTypes.insert(Ty);
} else if (Ty->isNullPtrType()) {
  HasNullPtrType = true;
} else if (AllowUserConversions && TyRec) {
  // No conversion functions in incomplete types.
  if (!SemaRef.isCompleteType(Loc, Ty))
    return;

  CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(TyRec->getDecl());
  for (NamedDecl *D : ClassDecl->getVisibleConversionFunctions()) {
    if (isa<UsingShadowDecl>(D))
      D = cast<UsingShadowDecl>(D)->getTargetDecl();

    // Skip conversion function templates; they don't tell us anything
    // about which builtin types we can convert to.
    if (isa<FunctionTemplateDecl>(D))
      continue;

    CXXConversionDecl *Conv = cast<CXXConversionDecl>(D);
    if (AllowExplicitConversions || !Conv->isExplicit()) {
      AddTypesConvertedFrom(Conv->getConversionType(), Loc, false, false,
                            VisibleQuals);
    }
  }
}
8053}
8054/// Helper function for adjusting address spaces for the pointer or reference
8055/// operands of builtin operators depending on the argument.
8056static QualType AdjustAddressSpaceForBuiltinOperandType(Sema &S, QualType T,
                                                      Expr *Arg) {
return S.Context.getAddrSpaceQualType(T, Arg->getType().getAddressSpace());
8059}

8061/// Helper function for AddBuiltinOperatorCandidates() that adds
8062/// the volatile- and non-volatile-qualified assignment operators for the
8063/// given type to the candidate set.
8064static void AddBuiltinAssignmentOperatorCandidates(Sema &S,
                                                 QualType T,
                                                 ArrayRef<Expr *> Args,
                                  OverloadCandidateSet &CandidateSet) {
QualType ParamTypes[2];

// T& operator=(T&, T)
ParamTypes[0] = S.Context.getLValueReferenceType(
    AdjustAddressSpaceForBuiltinOperandType(S, T, Args[0]));
ParamTypes[1] = T;
S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                      /*IsAssignmentOperator=*/true);

if (!S.Context.getCanonicalType(T).isVolatileQualified()) {
  // volatile T& operator=(volatile T&, T)
  ParamTypes[0] = S.Context.getLValueReferenceType(
      AdjustAddressSpaceForBuiltinOperandType(S, S.Context.getVolatileType(T),
                                              Args[0]));
  ParamTypes[1] = T;
  S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                        /*IsAssignmentOperator=*/true);
}
8086}

8088/// CollectVRQualifiers - This routine returns Volatile/Restrict qualifiers,
8089/// if any, found in visible type conversion functions found in ArgExpr's type.
8090static  Qualifiers CollectVRQualifiers(ASTContext &Context, Expr* ArgExpr) {
  Qualifiers VRQuals;
  const RecordType *TyRec;
  if (const MemberPointerType *RHSMPType =
      ArgExpr->getType()->getAs<MemberPointerType>())
    TyRec = RHSMPType->getClass()->getAs<RecordType>();
  else
    TyRec = ArgExpr->getType()->getAs<RecordType>();
  if (!TyRec) {
    // Just to be safe, assume the worst case.
    VRQuals.addVolatile();
    VRQuals.addRestrict();
    return VRQuals;
  }

  CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(TyRec->getDecl());
  if (!ClassDecl->hasDefinition())
    return VRQuals;

  for (NamedDecl *D : ClassDecl->getVisibleConversionFunctions()) {
    if (isa<UsingShadowDecl>(D))
      D = cast<UsingShadowDecl>(D)->getTargetDecl();
    if (CXXConversionDecl *Conv = dyn_cast<CXXConversionDecl>(D)) {
      QualType CanTy = Context.getCanonicalType(Conv->getConversionType());
      if (const ReferenceType *ResTypeRef = CanTy->getAs<ReferenceType>())
        CanTy = ResTypeRef->getPointeeType();
      // Need to go down the pointer/mempointer chain and add qualifiers
      // as see them.
      bool done = false;
      while (!done) {
        if (CanTy.isRestrictQualified())
          VRQuals.addRestrict();
        if (const PointerType *ResTypePtr = CanTy->getAs<PointerType>())
          CanTy = ResTypePtr->getPointeeType();
        else if (const MemberPointerType *ResTypeMPtr =
              CanTy->getAs<MemberPointerType>())
          CanTy = ResTypeMPtr->getPointeeType();
        else
          done = true;
        if (CanTy.isVolatileQualified())
          VRQuals.addVolatile();
        if (VRQuals.hasRestrict() && VRQuals.hasVolatile())
          return VRQuals;
      }
    }
  }
  return VRQuals;
8137}

8139namespace {

8141/// Helper class to manage the addition of builtin operator overload
8142/// candidates. It provides shared state and utility methods used throughout
8143/// the process, as well as a helper method to add each group of builtin
8144/// operator overloads from the standard to a candidate set.
8145class BuiltinOperatorOverloadBuilder {
// Common instance state available to all overload candidate addition methods.
Sema &S;
ArrayRef<Expr *> Args;
Qualifiers VisibleTypeConversionsQuals;
bool HasArithmeticOrEnumeralCandidateType;
SmallVectorImpl<BuiltinCandidateTypeSet> &CandidateTypes;
OverloadCandidateSet &CandidateSet;

static constexpr int ArithmeticTypesCap = 24;
SmallVector<CanQualType, ArithmeticTypesCap> ArithmeticTypes;

// Define some indices used to iterate over the arithmetic types in
// ArithmeticTypes.  The "promoted arithmetic types" are the arithmetic
// types are that preserved by promotion (C++ [over.built]p2).
unsigned FirstIntegralType,
         LastIntegralType;
unsigned FirstPromotedIntegralType,
         LastPromotedIntegralType;
unsigned FirstPromotedArithmeticType,
         LastPromotedArithmeticType;
unsigned NumArithmeticTypes;

void InitArithmeticTypes() {
  // Start of promoted types.
  FirstPromotedArithmeticType = 0;
  ArithmeticTypes.push_back(S.Context.FloatTy);
  ArithmeticTypes.push_back(S.Context.DoubleTy);
  ArithmeticTypes.push_back(S.Context.LongDoubleTy);
  if (S.Context.getTargetInfo().hasFloat128Type())
    ArithmeticTypes.push_back(S.Context.Float128Ty);

  // Start of integral types.
  FirstIntegralType = ArithmeticTypes.size();
  FirstPromotedIntegralType = ArithmeticTypes.size();
  ArithmeticTypes.push_back(S.Context.IntTy);
  ArithmeticTypes.push_back(S.Context.LongTy);
  ArithmeticTypes.push_back(S.Context.LongLongTy);
  if (S.Context.getTargetInfo().hasInt128Type() ||
      (S.Context.getAuxTargetInfo() &&
       S.Context.getAuxTargetInfo()->hasInt128Type()))
    ArithmeticTypes.push_back(S.Context.Int128Ty);
  ArithmeticTypes.push_back(S.Context.UnsignedIntTy);
  ArithmeticTypes.push_back(S.Context.UnsignedLongTy);
  ArithmeticTypes.push_back(S.Context.UnsignedLongLongTy);
  if (S.Context.getTargetInfo().hasInt128Type() ||
      (S.Context.getAuxTargetInfo() &&
       S.Context.getAuxTargetInfo()->hasInt128Type()))
    ArithmeticTypes.push_back(S.Context.UnsignedInt128Ty);
  LastPromotedIntegralType = ArithmeticTypes.size();
  LastPromotedArithmeticType = ArithmeticTypes.size();
  // End of promoted types.

  ArithmeticTypes.push_back(S.Context.BoolTy);
  ArithmeticTypes.push_back(S.Context.CharTy);
  ArithmeticTypes.push_back(S.Context.WCharTy);
  if (S.Context.getLangOpts().Char8)
    ArithmeticTypes.push_back(S.Context.Char8Ty);
  ArithmeticTypes.push_back(S.Context.Char16Ty);
  ArithmeticTypes.push_back(S.Context.Char32Ty);
  ArithmeticTypes.push_back(S.Context.SignedCharTy);
  ArithmeticTypes.push_back(S.Context.ShortTy);
  ArithmeticTypes.push_back(S.Context.UnsignedCharTy);
  ArithmeticTypes.push_back(S.Context.UnsignedShortTy);
  LastIntegralType = ArithmeticTypes.size();
  NumArithmeticTypes = ArithmeticTypes.size();
  // End of integral types.
  // FIXME: What about complex? What about half?

  assert(ArithmeticTypes.size() <= ArithmeticTypesCap &&((void)0)
         "Enough inline storage for all arithmetic types.")((void)0);
}

/// Helper method to factor out the common pattern of adding overloads
/// for '++' and '--' builtin operators.
void addPlusPlusMinusMinusStyleOverloads(QualType CandidateTy,
                                         bool HasVolatile,
                                         bool HasRestrict) {
  QualType ParamTypes[2] = {
    S.Context.getLValueReferenceType(CandidateTy),
    S.Context.IntTy
  };

  // Non-volatile version.
  S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);

  // Use a heuristic to reduce number of builtin candidates in the set:
  // add volatile version only if there are conversions to a volatile type.
  if (HasVolatile) {
    ParamTypes[0] =
      S.Context.getLValueReferenceType(
        S.Context.getVolatileType(CandidateTy));
    S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
  }

  // Add restrict version only if there are conversions to a restrict type
  // and our candidate type is a non-restrict-qualified pointer.
  if (HasRestrict && CandidateTy->isAnyPointerType() &&
      !CandidateTy.isRestrictQualified()) {
    ParamTypes[0]
      = S.Context.getLValueReferenceType(
          S.Context.getCVRQualifiedType(CandidateTy, Qualifiers::Restrict));
    S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);

    if (HasVolatile) {
      ParamTypes[0]
        = S.Context.getLValueReferenceType(
            S.Context.getCVRQualifiedType(CandidateTy,
                                          (Qualifiers::Volatile |
                                           Qualifiers::Restrict)));
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }
  }

}

/// Helper to add an overload candidate for a binary builtin with types \p L
/// and \p R.
void AddCandidate(QualType L, QualType R) {
  QualType LandR[2] = {L, R};
  S.AddBuiltinCandidate(LandR, Args, CandidateSet);
}

8268public:
BuiltinOperatorOverloadBuilder(
  Sema &S, ArrayRef<Expr *> Args,
  Qualifiers VisibleTypeConversionsQuals,
  bool HasArithmeticOrEnumeralCandidateType,
  SmallVectorImpl<BuiltinCandidateTypeSet> &CandidateTypes,
  OverloadCandidateSet &CandidateSet)
  : S(S), Args(Args),
    VisibleTypeConversionsQuals(VisibleTypeConversionsQuals),
    HasArithmeticOrEnumeralCandidateType(
      HasArithmeticOrEnumeralCandidateType),
    CandidateTypes(CandidateTypes),
    CandidateSet(CandidateSet) {

  InitArithmeticTypes();
}

// Increment is deprecated for bool since C++17.
//
// C++ [over.built]p3:
//
//   For every pair (T, VQ), where T is an arithmetic type other
//   than bool, and VQ is either volatile or empty, there exist
//   candidate operator functions of the form
//
//       VQ T&      operator++(VQ T&);
//       T          operator++(VQ T&, int);
//
// C++ [over.built]p4:
//
//   For every pair (T, VQ), where T is an arithmetic type other
//   than bool, and VQ is either volatile or empty, there exist
//   candidate operator functions of the form
//
//       VQ T&      operator--(VQ T&);
//       T          operator--(VQ T&, int);
void addPlusPlusMinusMinusArithmeticOverloads(OverloadedOperatorKind Op) {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Arith = 0; Arith < NumArithmeticTypes; ++Arith) {
    const auto TypeOfT = ArithmeticTypes[Arith];
    if (TypeOfT == S.Context.BoolTy) {
      if (Op == OO_MinusMinus)
        continue;
      if (Op == OO_PlusPlus && S.getLangOpts().CPlusPlus17)
        continue;
    }
    addPlusPlusMinusMinusStyleOverloads(
      TypeOfT,
      VisibleTypeConversionsQuals.hasVolatile(),
      VisibleTypeConversionsQuals.hasRestrict());
  }
}

// C++ [over.built]p5:
//
//   For every pair (T, VQ), where T is a cv-qualified or
//   cv-unqualified object type, and VQ is either volatile or
//   empty, there exist candidate operator functions of the form
//
//       T*VQ&      operator++(T*VQ&);
//       T*VQ&      operator--(T*VQ&);
//       T*         operator++(T*VQ&, int);
//       T*         operator--(T*VQ&, int);
void addPlusPlusMinusMinusPointerOverloads() {
  for (QualType PtrTy : CandidateTypes[0].pointer_types()) {
    // Skip pointer types that aren't pointers to object types.
    if (!PtrTy->getPointeeType()->isObjectType())
      continue;

    addPlusPlusMinusMinusStyleOverloads(
        PtrTy,
        (!PtrTy.isVolatileQualified() &&
         VisibleTypeConversionsQuals.hasVolatile()),
        (!PtrTy.isRestrictQualified() &&
         VisibleTypeConversionsQuals.hasRestrict()));
  }
}

// C++ [over.built]p6:
//   For every cv-qualified or cv-unqualified object type T, there
//   exist candidate operator functions of the form
//
//       T&         operator*(T*);
//
// C++ [over.built]p7:
//   For every function type T that does not have cv-qualifiers or a
//   ref-qualifier, there exist candidate operator functions of the form
//       T&         operator*(T*);
void addUnaryStarPointerOverloads() {
  for (QualType ParamTy : CandidateTypes[0].pointer_types()) {
    QualType PointeeTy = ParamTy->getPointeeType();
    if (!PointeeTy->isObjectType() && !PointeeTy->isFunctionType())
      continue;

    if (const FunctionProtoType *Proto =PointeeTy->getAs<FunctionProtoType>())
      if (Proto->getMethodQuals() || Proto->getRefQualifier())
        continue;

    S.AddBuiltinCandidate(&ParamTy, Args, CandidateSet);
  }
}

// C++ [over.built]p9:
//  For every promoted arithmetic type T, there exist candidate
//  operator functions of the form
//
//       T         operator+(T);
//       T         operator-(T);
void addUnaryPlusOrMinusArithmeticOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Arith = FirstPromotedArithmeticType;
       Arith < LastPromotedArithmeticType; ++Arith) {
    QualType ArithTy = ArithmeticTypes[Arith];
    S.AddBuiltinCandidate(&ArithTy, Args, CandidateSet);
  }

  // Extension: We also add these operators for vector types.
  for (QualType VecTy : CandidateTypes[0].vector_types())
    S.AddBuiltinCandidate(&VecTy, Args, CandidateSet);
}

// C++ [over.built]p8:
//   For every type T, there exist candidate operator functions of
//   the form
//
//       T*         operator+(T*);
void addUnaryPlusPointerOverloads() {
  for (QualType ParamTy : CandidateTypes[0].pointer_types())
    S.AddBuiltinCandidate(&ParamTy, Args, CandidateSet);
}

// C++ [over.built]p10:
//   For every promoted integral type T, there exist candidate
//   operator functions of the form
//
//        T         operator~(T);
void addUnaryTildePromotedIntegralOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Int = FirstPromotedIntegralType;
       Int < LastPromotedIntegralType; ++Int) {
    QualType IntTy = ArithmeticTypes[Int];
    S.AddBuiltinCandidate(&IntTy, Args, CandidateSet);
  }

  // Extension: We also add this operator for vector types.
  for (QualType VecTy : CandidateTypes[0].vector_types())
    S.AddBuiltinCandidate(&VecTy, Args, CandidateSet);
}

// C++ [over.match.oper]p16:
//   For every pointer to member type T or type std::nullptr_t, there
//   exist candidate operator functions of the form
//
//        bool operator==(T,T);
//        bool operator!=(T,T);
void addEqualEqualOrNotEqualMemberPointerOrNullptrOverloads() {
  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
    for (QualType MemPtrTy : CandidateTypes[ArgIdx].member_pointer_types()) {
      // Don't add the same builtin candidate twice.
      if (!AddedTypes.insert(S.Context.getCanonicalType(MemPtrTy)).second)
        continue;

      QualType ParamTypes[2] = {MemPtrTy, MemPtrTy};
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }

    if (CandidateTypes[ArgIdx].hasNullPtrType()) {
      CanQualType NullPtrTy = S.Context.getCanonicalType(S.Context.NullPtrTy);
      if (AddedTypes.insert(NullPtrTy).second) {
        QualType ParamTypes[2] = { NullPtrTy, NullPtrTy };
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
      }
    }
  }
}

// C++ [over.built]p15:
//
//   For every T, where T is an enumeration type or a pointer type,
//   there exist candidate operator functions of the form
//
//        bool       operator<(T, T);
//        bool       operator>(T, T);
//        bool       operator<=(T, T);
//        bool       operator>=(T, T);
//        bool       operator==(T, T);
//        bool       operator!=(T, T);
//           R       operator<=>(T, T)
void addGenericBinaryPointerOrEnumeralOverloads(bool IsSpaceship) {
  // C++ [over.match.oper]p3:
  //   [...]the built-in candidates include all of the candidate operator
  //   functions defined in 13.6 that, compared to the given operator, [...]
  //   do not have the same parameter-type-list as any non-template non-member
  //   candidate.
  //
  // Note that in practice, this only affects enumeration types because there
  // aren't any built-in candidates of record type, and a user-defined operator
  // must have an operand of record or enumeration type. Also, the only other
  // overloaded operator with enumeration arguments, operator=,
  // cannot be overloaded for enumeration types, so this is the only place
  // where we must suppress candidates like this.
  llvm::DenseSet<std::pair<CanQualType, CanQualType> >
    UserDefinedBinaryOperators;

  for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
    if (!CandidateTypes[ArgIdx].enumeration_types().empty()) {
      for (OverloadCandidateSet::iterator C = CandidateSet.begin(),
                                       CEnd = CandidateSet.end();
           C != CEnd; ++C) {
        if (!C->Viable || !C->Function || C->Function->getNumParams() != 2)
          continue;

        if (C->Function->isFunctionTemplateSpecialization())
          continue;

        // We interpret "same parameter-type-list" as applying to the
        // "synthesized candidate, with the order of the two parameters
        // reversed", not to the original function.
        bool Reversed = C->isReversed();
        QualType FirstParamType = C->Function->getParamDecl(Reversed ? 1 : 0)
                                      ->getType()
                                      .getUnqualifiedType();
        QualType SecondParamType = C->Function->getParamDecl(Reversed ? 0 : 1)
                                       ->getType()
                                       .getUnqualifiedType();

        // Skip if either parameter isn't of enumeral type.
        if (!FirstParamType->isEnumeralType() ||
            !SecondParamType->isEnumeralType())
          continue;

        // Add this operator to the set of known user-defined operators.
        UserDefinedBinaryOperators.insert(
          std::make_pair(S.Context.getCanonicalType(FirstParamType),
                         S.Context.getCanonicalType(SecondParamType)));
      }
    }
  }

  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
    for (QualType PtrTy : CandidateTypes[ArgIdx].pointer_types()) {
      // Don't add the same builtin candidate twice.
      if (!AddedTypes.insert(S.Context.getCanonicalType(PtrTy)).second)
        continue;
      if (IsSpaceship && PtrTy->isFunctionPointerType())
        continue;

      QualType ParamTypes[2] = {PtrTy, PtrTy};
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }
    for (QualType EnumTy : CandidateTypes[ArgIdx].enumeration_types()) {
      CanQualType CanonType = S.Context.getCanonicalType(EnumTy);

      // Don't add the same builtin candidate twice, or if a user defined
      // candidate exists.
      if (!AddedTypes.insert(CanonType).second ||
          UserDefinedBinaryOperators.count(std::make_pair(CanonType,
                                                          CanonType)))
        continue;
      QualType ParamTypes[2] = {EnumTy, EnumTy};
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }
  }
}

// C++ [over.built]p13:
//
//   For every cv-qualified or cv-unqualified object type T
//   there exist candidate operator functions of the form
//
//      T*         operator+(T*, ptrdiff_t);
//      T&         operator[](T*, ptrdiff_t);    [BELOW]
//      T*         operator-(T*, ptrdiff_t);
//      T*         operator+(ptrdiff_t, T*);
//      T&         operator[](ptrdiff_t, T*);    [BELOW]
//
// C++ [over.built]p14:
//
//   For every T, where T is a pointer to object type, there
//   exist candidate operator functions of the form
//
//      ptrdiff_t  operator-(T, T);
void addBinaryPlusOrMinusPointerOverloads(OverloadedOperatorKind Op) {
  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (int Arg = 0; Arg < 2; ++Arg) {
    QualType AsymmetricParamTypes[2] = {
      S.Context.getPointerDiffType(),
      S.Context.getPointerDiffType(),
    };
    for (QualType PtrTy : CandidateTypes[Arg].pointer_types()) {
      QualType PointeeTy = PtrTy->getPointeeType();
      if (!PointeeTy->isObjectType())
        continue;

      AsymmetricParamTypes[Arg] = PtrTy;
      if (Arg == 0 || Op == OO_Plus) {
        // operator+(T*, ptrdiff_t) or operator-(T*, ptrdiff_t)
        // T* operator+(ptrdiff_t, T*);
        S.AddBuiltinCandidate(AsymmetricParamTypes, Args, CandidateSet);
      }
      if (Op == OO_Minus) {
        // ptrdiff_t operator-(T, T);
        if (!AddedTypes.insert(S.Context.getCanonicalType(PtrTy)).second)
          continue;

        QualType ParamTypes[2] = {PtrTy, PtrTy};
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
      }
    }
  }
}

// C++ [over.built]p12:
//
//   For every pair of promoted arithmetic types L and R, there
//   exist candidate operator functions of the form
//
//        LR         operator*(L, R);
//        LR         operator/(L, R);
//        LR         operator+(L, R);
//        LR         operator-(L, R);
//        bool       operator<(L, R);
//        bool       operator>(L, R);
//        bool       operator<=(L, R);
//        bool       operator>=(L, R);
//        bool       operator==(L, R);
//        bool       operator!=(L, R);
//
//   where LR is the result of the usual arithmetic conversions
//   between types L and R.
//
// C++ [over.built]p24:
//
//   For every pair of promoted arithmetic types L and R, there exist
//   candidate operator functions of the form
//
//        LR       operator?(bool, L, R);
//
//   where LR is the result of the usual arithmetic conversions
//   between types L and R.
// Our candidates ignore the first parameter.
void addGenericBinaryArithmeticOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Left = FirstPromotedArithmeticType;
       Left < LastPromotedArithmeticType; ++Left) {
    for (unsigned Right = FirstPromotedArithmeticType;
         Right < LastPromotedArithmeticType; ++Right) {
      QualType LandR[2] = { ArithmeticTypes[Left],
                            ArithmeticTypes[Right] };
      S.AddBuiltinCandidate(LandR, Args, CandidateSet);
    }
  }

  // Extension: Add the binary operators ==, !=, <, <=, >=, >, *, /, and the
  // conditional operator for vector types.
  for (QualType Vec1Ty : CandidateTypes[0].vector_types())
    for (QualType Vec2Ty : CandidateTypes[1].vector_types()) {
      QualType LandR[2] = {Vec1Ty, Vec2Ty};
      S.AddBuiltinCandidate(LandR, Args, CandidateSet);
    }
}

/// Add binary operator overloads for each candidate matrix type M1, M2:
///  * (M1, M1) -> M1
///  * (M1, M1.getElementType()) -> M1
///  * (M2.getElementType(), M2) -> M2
///  * (M2, M2) -> M2 // Only if M2 is not part of CandidateTypes[0].
void addMatrixBinaryArithmeticOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (QualType M1 : CandidateTypes[0].matrix_types()) {
    AddCandidate(M1, cast<MatrixType>(M1)->getElementType());
    AddCandidate(M1, M1);
  }

  for (QualType M2 : CandidateTypes[1].matrix_types()) {
    AddCandidate(cast<MatrixType>(M2)->getElementType(), M2);
    if (!CandidateTypes[0].containsMatrixType(M2))
      AddCandidate(M2, M2);
  }
}

// C++2a [over.built]p14:
//
//   For every integral type T there exists a candidate operator function
//   of the form
//
//        std::strong_ordering operator<=>(T, T)
//
// C++2a [over.built]p15:
//
//   For every pair of floating-point types L and R, there exists a candidate
//   operator function of the form
//
//       std::partial_ordering operator<=>(L, R);
//
// FIXME: The current specification for integral types doesn't play nice with
// the direction of p0946r0, which allows mixed integral and unscoped-enum
// comparisons. Under the current spec this can lead to ambiguity during
// overload resolution. For example:
//
//   enum A : int {a};
//   auto x = (a <=> (long)42);
//
//   error: call is ambiguous for arguments 'A' and 'long'.
//   note: candidate operator<=>(int, int)
//   note: candidate operator<=>(long, long)
//
// To avoid this error, this function deviates from the specification and adds
// the mixed overloads `operator<=>(L, R)` where L and R are promoted
// arithmetic types (the same as the generic relational overloads).
//
// For now this function acts as a placeholder.
void addThreeWayArithmeticOverloads() {
  addGenericBinaryArithmeticOverloads();
}

// C++ [over.built]p17:
//
//   For every pair of promoted integral types L and R, there
//   exist candidate operator functions of the form
//
//      LR         operator%(L, R);
//      LR         operator&(L, R);
//      LR         operator^(L, R);
//      LR         operator|(L, R);
//      L          operator<<(L, R);
//      L          operator>>(L, R);
//
//   where LR is the result of the usual arithmetic conversions
//   between types L and R.
void addBinaryBitwiseArithmeticOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Left = FirstPromotedIntegralType;
       Left < LastPromotedIntegralType; ++Left) {
    for (unsigned Right = FirstPromotedIntegralType;
         Right < LastPromotedIntegralType; ++Right) {
      QualType LandR[2] = { ArithmeticTypes[Left],
                            ArithmeticTypes[Right] };
      S.AddBuiltinCandidate(LandR, Args, CandidateSet);
    }
  }
}

// C++ [over.built]p20:
//
//   For every pair (T, VQ), where T is an enumeration or
//   pointer to member type and VQ is either volatile or
//   empty, there exist candidate operator functions of the form
//
//        VQ T&      operator=(VQ T&, T);
void addAssignmentMemberPointerOrEnumeralOverloads() {
  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (unsigned ArgIdx = 0; ArgIdx < 2; ++ArgIdx) {
    for (QualType EnumTy : CandidateTypes[ArgIdx].enumeration_types()) {
      if (!AddedTypes.insert(S.Context.getCanonicalType(EnumTy)).second)
        continue;

      AddBuiltinAssignmentOperatorCandidates(S, EnumTy, Args, CandidateSet);
    }

    for (QualType MemPtrTy : CandidateTypes[ArgIdx].member_pointer_types()) {
      if (!AddedTypes.insert(S.Context.getCanonicalType(MemPtrTy)).second)
        continue;

      AddBuiltinAssignmentOperatorCandidates(S, MemPtrTy, Args, CandidateSet);
    }
  }
}

// C++ [over.built]p19:
//
//   For every pair (T, VQ), where T is any type and VQ is either
//   volatile or empty, there exist candidate operator functions
//   of the form
//
//        T*VQ&      operator=(T*VQ&, T*);
//
// C++ [over.built]p21:
//
//   For every pair (T, VQ), where T is a cv-qualified or
//   cv-unqualified object type and VQ is either volatile or
//   empty, there exist candidate operator functions of the form
//
//        T*VQ&      operator+=(T*VQ&, ptrdiff_t);
//        T*VQ&      operator-=(T*VQ&, ptrdiff_t);
void addAssignmentPointerOverloads(bool isEqualOp) {
  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (QualType PtrTy : CandidateTypes[0].pointer_types()) {
    // If this is operator=, keep track of the builtin candidates we added.
    if (isEqualOp)
      AddedTypes.insert(S.Context.getCanonicalType(PtrTy));
    else if (!PtrTy->getPointeeType()->isObjectType())
      continue;

    // non-volatile version
    QualType ParamTypes[2] = {
        S.Context.getLValueReferenceType(PtrTy),
        isEqualOp ? PtrTy : S.Context.getPointerDiffType(),
    };
    S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                          /*IsAssignmentOperator=*/ isEqualOp);

    bool NeedVolatile = !PtrTy.isVolatileQualified() &&
                        VisibleTypeConversionsQuals.hasVolatile();
    if (NeedVolatile) {
      // volatile version
      ParamTypes[0] =
          S.Context.getLValueReferenceType(S.Context.getVolatileType(PtrTy));
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                            /*IsAssignmentOperator=*/isEqualOp);
    }

    if (!PtrTy.isRestrictQualified() &&
        VisibleTypeConversionsQuals.hasRestrict()) {
      // restrict version
      ParamTypes[0] =
          S.Context.getLValueReferenceType(S.Context.getRestrictType(PtrTy));
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                            /*IsAssignmentOperator=*/isEqualOp);

      if (NeedVolatile) {
        // volatile restrict version
        ParamTypes[0] =
            S.Context.getLValueReferenceType(S.Context.getCVRQualifiedType(
                PtrTy, (Qualifiers::Volatile | Qualifiers::Restrict)));
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                              /*IsAssignmentOperator=*/isEqualOp);
      }
    }
  }

  if (isEqualOp) {
    for (QualType PtrTy : CandidateTypes[1].pointer_types()) {
      // Make sure we don't add the same candidate twice.
      if (!AddedTypes.insert(S.Context.getCanonicalType(PtrTy)).second)
        continue;

      QualType ParamTypes[2] = {
          S.Context.getLValueReferenceType(PtrTy),
          PtrTy,
      };

      // non-volatile version
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                            /*IsAssignmentOperator=*/true);

      bool NeedVolatile = !PtrTy.isVolatileQualified() &&
                          VisibleTypeConversionsQuals.hasVolatile();
      if (NeedVolatile) {
        // volatile version
        ParamTypes[0] = S.Context.getLValueReferenceType(
            S.Context.getVolatileType(PtrTy));
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                              /*IsAssignmentOperator=*/true);
      }

      if (!PtrTy.isRestrictQualified() &&
          VisibleTypeConversionsQuals.hasRestrict()) {
        // restrict version
        ParamTypes[0] = S.Context.getLValueReferenceType(
            S.Context.getRestrictType(PtrTy));
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                              /*IsAssignmentOperator=*/true);

        if (NeedVolatile) {
          // volatile restrict version
          ParamTypes[0] =
              S.Context.getLValueReferenceType(S.Context.getCVRQualifiedType(
                  PtrTy, (Qualifiers::Volatile | Qualifiers::Restrict)));
          S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                                /*IsAssignmentOperator=*/true);
        }
      }
    }
  }
}

// C++ [over.built]p18:
//
//   For every triple (L, VQ, R), where L is an arithmetic type,
//   VQ is either volatile or empty, and R is a promoted
//   arithmetic type, there exist candidate operator functions of
//   the form
//
//        VQ L&      operator=(VQ L&, R);
//        VQ L&      operator*=(VQ L&, R);
//        VQ L&      operator/=(VQ L&, R);
//        VQ L&      operator+=(VQ L&, R);
//        VQ L&      operator-=(VQ L&, R);
void addAssignmentArithmeticOverloads(bool isEqualOp) {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Left = 0; Left < NumArithmeticTypes; ++Left) {
    for (unsigned Right = FirstPromotedArithmeticType;
         Right < LastPromotedArithmeticType; ++Right) {
      QualType ParamTypes[2];
      ParamTypes[1] = ArithmeticTypes[Right];
      auto LeftBaseTy = AdjustAddressSpaceForBuiltinOperandType(
          S, ArithmeticTypes[Left], Args[0]);
      // Add this built-in operator as a candidate (VQ is empty).
      ParamTypes[0] = S.Context.getLValueReferenceType(LeftBaseTy);
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                            /*IsAssignmentOperator=*/isEqualOp);

      // Add this built-in operator as a candidate (VQ is 'volatile').
      if (VisibleTypeConversionsQuals.hasVolatile()) {
        ParamTypes[0] = S.Context.getVolatileType(LeftBaseTy);
        ParamTypes[0] = S.Context.getLValueReferenceType(ParamTypes[0]);
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                              /*IsAssignmentOperator=*/isEqualOp);
      }
    }
  }

  // Extension: Add the binary operators =, +=, -=, *=, /= for vector types.
  for (QualType Vec1Ty : CandidateTypes[0].vector_types())
    for (QualType Vec2Ty : CandidateTypes[0].vector_types()) {
      QualType ParamTypes[2];
      ParamTypes[1] = Vec2Ty;
      // Add this built-in operator as a candidate (VQ is empty).
      ParamTypes[0] = S.Context.getLValueReferenceType(Vec1Ty);
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                            /*IsAssignmentOperator=*/isEqualOp);

      // Add this built-in operator as a candidate (VQ is 'volatile').
      if (VisibleTypeConversionsQuals.hasVolatile()) {
        ParamTypes[0] = S.Context.getVolatileType(Vec1Ty);
        ParamTypes[0] = S.Context.getLValueReferenceType(ParamTypes[0]);
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                              /*IsAssignmentOperator=*/isEqualOp);
      }
    }
}

// C++ [over.built]p22:
//
//   For every triple (L, VQ, R), where L is an integral type, VQ
//   is either volatile or empty, and R is a promoted integral
//   type, there exist candidate operator functions of the form
//
//        VQ L&       operator%=(VQ L&, R);
//        VQ L&       operator<<=(VQ L&, R);
//        VQ L&       operator>>=(VQ L&, R);
//        VQ L&       operator&=(VQ L&, R);
//        VQ L&       operator^=(VQ L&, R);
//        VQ L&       operator|=(VQ L&, R);
void addAssignmentIntegralOverloads() {
  if (!HasArithmeticOrEnumeralCandidateType)
    return;

  for (unsigned Left = FirstIntegralType; Left < LastIntegralType; ++Left) {
    for (unsigned Right = FirstPromotedIntegralType;
         Right < LastPromotedIntegralType; ++Right) {
      QualType ParamTypes[2];
      ParamTypes[1] = ArithmeticTypes[Right];
      auto LeftBaseTy = AdjustAddressSpaceForBuiltinOperandType(
          S, ArithmeticTypes[Left], Args[0]);
      // Add this built-in operator as a candidate (VQ is empty).
      ParamTypes[0] = S.Context.getLValueReferenceType(LeftBaseTy);
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
      if (VisibleTypeConversionsQuals.hasVolatile()) {
        // Add this built-in operator as a candidate (VQ is 'volatile').
        ParamTypes[0] = LeftBaseTy;
        ParamTypes[0] = S.Context.getVolatileType(ParamTypes[0]);
        ParamTypes[0] = S.Context.getLValueReferenceType(ParamTypes[0]);
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
      }
    }
  }
}

// C++ [over.operator]p23:
//
//   There also exist candidate operator functions of the form
//
//        bool        operator!(bool);
//        bool        operator&&(bool, bool);
//        bool        operator||(bool, bool);
void addExclaimOverload() {
  QualType ParamTy = S.Context.BoolTy;
  S.AddBuiltinCandidate(&ParamTy, Args, CandidateSet,
                        /*IsAssignmentOperator=*/false,
                        /*NumContextualBoolArguments=*/1);
}
void addAmpAmpOrPipePipeOverload() {
  QualType ParamTypes[2] = { S.Context.BoolTy, S.Context.BoolTy };
  S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet,
                        /*IsAssignmentOperator=*/false,
                        /*NumContextualBoolArguments=*/2);
}

// C++ [over.built]p13:
//
//   For every cv-qualified or cv-unqualified object type T there
//   exist candidate operator functions of the form
//
//        T*         operator+(T*, ptrdiff_t);     [ABOVE]
//        T&         operator[](T*, ptrdiff_t);
//        T*         operator-(T*, ptrdiff_t);     [ABOVE]
//        T*         operator+(ptrdiff_t, T*);     [ABOVE]
//        T&         operator[](ptrdiff_t, T*);
void addSubscriptOverloads() {
  for (QualType PtrTy : CandidateTypes[0].pointer_types()) {
    QualType ParamTypes[2] = {PtrTy, S.Context.getPointerDiffType()};
    QualType PointeeType = PtrTy->getPointeeType();
    if (!PointeeType->isObjectType())
      continue;

    // T& operator[](T*, ptrdiff_t)
    S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
  }

  for (QualType PtrTy : CandidateTypes[1].pointer_types()) {
    QualType ParamTypes[2] = {S.Context.getPointerDiffType(), PtrTy};
    QualType PointeeType = PtrTy->getPointeeType();
    if (!PointeeType->isObjectType())
      continue;

    // T& operator[](ptrdiff_t, T*)
    S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
  }
}

// C++ [over.built]p11:
//    For every quintuple (C1, C2, T, CV1, CV2), where C2 is a class type,
//    C1 is the same type as C2 or is a derived class of C2, T is an object
//    type or a function type, and CV1 and CV2 are cv-qualifier-seqs,
//    there exist candidate operator functions of the form
//
//      CV12 T& operator->*(CV1 C1*, CV2 T C2::*);
//
//    where CV12 is the union of CV1 and CV2.
void addArrowStarOverloads() {
  for (QualType PtrTy : CandidateTypes[0].pointer_types()) {
    QualType C1Ty = PtrTy;
    QualType C1;
    QualifierCollector Q1;
    C1 = QualType(Q1.strip(C1Ty->getPointeeType()), 0);
    if (!isa<RecordType>(C1))
      continue;
    // heuristic to reduce number of builtin candidates in the set.
    // Add volatile/restrict version only if there are conversions to a
    // volatile/restrict type.
    if (!VisibleTypeConversionsQuals.hasVolatile() && Q1.hasVolatile())
      continue;
    if (!VisibleTypeConversionsQuals.hasRestrict() && Q1.hasRestrict())
      continue;
    for (QualType MemPtrTy : CandidateTypes[1].member_pointer_types()) {
      const MemberPointerType *mptr = cast<MemberPointerType>(MemPtrTy);
      QualType C2 = QualType(mptr->getClass(), 0);
      C2 = C2.getUnqualifiedType();
      if (C1 != C2 && !S.IsDerivedFrom(CandidateSet.getLocation(), C1, C2))
        break;
      QualType ParamTypes[2] = {PtrTy, MemPtrTy};
      // build CV12 T&
      QualType T = mptr->getPointeeType();
      if (!VisibleTypeConversionsQuals.hasVolatile() &&
          T.isVolatileQualified())
        continue;
      if (!VisibleTypeConversionsQuals.hasRestrict() &&
          T.isRestrictQualified())
        continue;
      T = Q1.apply(S.Context, T);
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }
  }
}

// Note that we don't consider the first argument, since it has been
// contextually converted to bool long ago. The candidates below are
// therefore added as binary.
//
// C++ [over.built]p25:
//   For every type T, where T is a pointer, pointer-to-member, or scoped
//   enumeration type, there exist candidate operator functions of the form
//
//        T        operator?(bool, T, T);
//
void addConditionalOperatorOverloads() {
  /// Set of (canonical) types that we've already handled.
  llvm::SmallPtrSet<QualType, 8> AddedTypes;

  for (unsigned ArgIdx = 0; ArgIdx < 2; ++ArgIdx) {
    for (QualType PtrTy : CandidateTypes[ArgIdx].pointer_types()) {
      if (!AddedTypes.insert(S.Context.getCanonicalType(PtrTy)).second)
        continue;

      QualType ParamTypes[2] = {PtrTy, PtrTy};
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }

    for (QualType MemPtrTy : CandidateTypes[ArgIdx].member_pointer_types()) {
      if (!AddedTypes.insert(S.Context.getCanonicalType(MemPtrTy)).second)
        continue;

      QualType ParamTypes[2] = {MemPtrTy, MemPtrTy};
      S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
    }

    if (S.getLangOpts().CPlusPlus11) {
      for (QualType EnumTy : CandidateTypes[ArgIdx].enumeration_types()) {
        if (!EnumTy->castAs<EnumType>()->getDecl()->isScoped())
          continue;

        if (!AddedTypes.insert(S.Context.getCanonicalType(EnumTy)).second)
          continue;

        QualType ParamTypes[2] = {EnumTy, EnumTy};
        S.AddBuiltinCandidate(ParamTypes, Args, CandidateSet);
      }
    }
  }
}
9106};

9108} // end anonymous namespace

9110/// AddBuiltinOperatorCandidates - Add the appropriate built-in
9111/// operator overloads to the candidate set (C++ [over.built]), based
9112/// on the operator @p Op and the arguments given. For example, if the
9113/// operator is a binary '+', this routine might add "int
9114/// operator+(int, int)" to cover integer addition.
9115void Sema::AddBuiltinOperatorCandidates(OverloadedOperatorKind Op,
                                      SourceLocation OpLoc,
                                      ArrayRef<Expr *> Args,
                                      OverloadCandidateSet &CandidateSet) {
// Find all of the types that the arguments can convert to, but only
// if the operator we're looking at has built-in operator candidates
// that make use of these types. Also record whether we encounter non-record
// candidate types or either arithmetic or enumeral candidate types.
Qualifiers VisibleTypeConversionsQuals;
VisibleTypeConversionsQuals.addConst();
for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx)
  VisibleTypeConversionsQuals += CollectVRQualifiers(Context, Args[ArgIdx]);

bool HasNonRecordCandidateType = false;
bool HasArithmeticOrEnumeralCandidateType = false;
SmallVector<BuiltinCandidateTypeSet, 2> CandidateTypes;
for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
  CandidateTypes.emplace_back(*this);
  CandidateTypes[ArgIdx].AddTypesConvertedFrom(Args[ArgIdx]->getType(),
                                               OpLoc,
                                               true,
                                               (Op == OO_Exclaim ||
                                                Op == OO_AmpAmp ||
                                                Op == OO_PipePipe),
                                               VisibleTypeConversionsQuals);
  HasNonRecordCandidateType = HasNonRecordCandidateType ||
      CandidateTypes[ArgIdx].hasNonRecordTypes();
  HasArithmeticOrEnumeralCandidateType =
      HasArithmeticOrEnumeralCandidateType ||
      CandidateTypes[ArgIdx].hasArithmeticOrEnumeralTypes();
}

// Exit early when no non-record types have been added to the candidate set
// for any of the arguments to the operator.
//
// We can't exit early for !, ||, or &&, since there we have always have
// 'bool' overloads.
if (!HasNonRecordCandidateType &&
    !(Op == OO_Exclaim || Op == OO_AmpAmp || Op == OO_PipePipe))
  return;

// Setup an object to manage the common state for building overloads.
BuiltinOperatorOverloadBuilder OpBuilder(*this, Args,
                                         VisibleTypeConversionsQuals,
                                         HasArithmeticOrEnumeralCandidateType,
                                         CandidateTypes, CandidateSet);

// Dispatch over the operation to add in only those overloads which apply.
switch (Op) {
case OO_None:
case NUM_OVERLOADED_OPERATORS:
  llvm_unreachable("Expected an overloaded operator")__builtin_unreachable();

case OO_New:
case OO_Delete:
case OO_Array_New:
case OO_Array_Delete:
case OO_Call:
  llvm_unreachable(__builtin_unreachable()
                  "Special operators don't use AddBuiltinOperatorCandidates")__builtin_unreachable();

case OO_Comma:
case OO_Arrow:
case OO_Coawait:
  // C++ [over.match.oper]p3:
  //   -- For the operator ',', the unary operator '&', the
  //      operator '->', or the operator 'co_await', the
  //      built-in candidates set is empty.
  break;

case OO_Plus: // '+' is either unary or binary
  if (Args.size() == 1)
    OpBuilder.addUnaryPlusPointerOverloads();
  LLVM_FALLTHROUGH[[gnu::fallthrough]];

case OO_Minus: // '-' is either unary or binary
  if (Args.size() == 1) {
    OpBuilder.addUnaryPlusOrMinusArithmeticOverloads();
  } else {
    OpBuilder.addBinaryPlusOrMinusPointerOverloads(Op);
    OpBuilder.addGenericBinaryArithmeticOverloads();
    OpBuilder.addMatrixBinaryArithmeticOverloads();
  }
  break;

case OO_Star: // '*' is either unary or binary
  if (Args.size() == 1)
    OpBuilder.addUnaryStarPointerOverloads();
  else {
    OpBuilder.addGenericBinaryArithmeticOverloads();
    OpBuilder.addMatrixBinaryArithmeticOverloads();
  }
  break;

case OO_Slash:
  OpBuilder.addGenericBinaryArithmeticOverloads();
  break;

case OO_PlusPlus:
case OO_MinusMinus:
  OpBuilder.addPlusPlusMinusMinusArithmeticOverloads(Op);
  OpBuilder.addPlusPlusMinusMinusPointerOverloads();
  break;

case OO_EqualEqual:
case OO_ExclaimEqual:
  OpBuilder.addEqualEqualOrNotEqualMemberPointerOrNullptrOverloads();
  OpBuilder.addGenericBinaryPointerOrEnumeralOverloads(/*IsSpaceship=*/false);
  OpBuilder.addGenericBinaryArithmeticOverloads();
  break;

case OO_Less:
case OO_Greater:
case OO_LessEqual:
case OO_GreaterEqual:
  OpBuilder.addGenericBinaryPointerOrEnumeralOverloads(/*IsSpaceship=*/false);
  OpBuilder.addGenericBinaryArithmeticOverloads();
  break;

case OO_Spaceship:
  OpBuilder.addGenericBinaryPointerOrEnumeralOverloads(/*IsSpaceship=*/true);
  OpBuilder.addThreeWayArithmeticOverloads();
  break;

case OO_Percent:
case OO_Caret:
case OO_Pipe:
case OO_LessLess:
case OO_GreaterGreater:
  OpBuilder.addBinaryBitwiseArithmeticOverloads();
  break;

case OO_Amp: // '&' is either unary or binary
  if (Args.size() == 1)
    // C++ [over.match.oper]p3:
    //   -- For the operator ',', the unary operator '&', or the
    //      operator '->', the built-in candidates set is empty.
    break;

  OpBuilder.addBinaryBitwiseArithmeticOverloads();
  break;

case OO_Tilde:
  OpBuilder.addUnaryTildePromotedIntegralOverloads();
  break;

case OO_Equal:
  OpBuilder.addAssignmentMemberPointerOrEnumeralOverloads();
  LLVM_FALLTHROUGH[[gnu::fallthrough]];

case OO_PlusEqual:
case OO_MinusEqual:
  OpBuilder.addAssignmentPointerOverloads(Op == OO_Equal);
  LLVM_FALLTHROUGH[[gnu::fallthrough]];

case OO_StarEqual:
case OO_SlashEqual:
  OpBuilder.addAssignmentArithmeticOverloads(Op == OO_Equal);
  break;

case OO_PercentEqual:
case OO_LessLessEqual:
case OO_GreaterGreaterEqual:
case OO_AmpEqual:
case OO_CaretEqual:
case OO_PipeEqual:
  OpBuilder.addAssignmentIntegralOverloads();
  break;

case OO_Exclaim:
  OpBuilder.addExclaimOverload();
  break;

case OO_AmpAmp:
case OO_PipePipe:
  OpBuilder.addAmpAmpOrPipePipeOverload();
  break;

case OO_Subscript:
  OpBuilder.addSubscriptOverloads();
  break;

case OO_ArrowStar:
  OpBuilder.addArrowStarOverloads();
  break;

case OO_Conditional:
  OpBuilder.addConditionalOperatorOverloads();
  OpBuilder.addGenericBinaryArithmeticOverloads();
  break;
}
9306}

9308/// Add function candidates found via argument-dependent lookup
9309/// to the set of overloading candidates.
9310///
9311/// This routine performs argument-dependent name lookup based on the
9312/// given function name (which may also be an operator name) and adds
9313/// all of the overload candidates found by ADL to the overload
9314/// candidate set (C++ [basic.lookup.argdep]).
9315void
9316Sema::AddArgumentDependentLookupCandidates(DeclarationName Name,
                                         SourceLocation Loc,
                                         ArrayRef<Expr *> Args,
                               TemplateArgumentListInfo *ExplicitTemplateArgs,
                                         OverloadCandidateSet& CandidateSet,
                                         bool PartialOverloading) {
ADLResult Fns;

// FIXME: This approach for uniquing ADL results (and removing
// redundant candidates from the set) relies on pointer-equality,
// which means we need to key off the canonical decl.  However,
// always going back to the canonical decl might not get us the
// right set of default arguments.  What default arguments are
// we supposed to consider on ADL candidates, anyway?

// FIXME: Pass in the explicit template arguments?
ArgumentDependentLookup(Name, Loc, Args, Fns);

// Erase all of the candidates we already knew about.
for (OverloadCandidateSet::iterator Cand = CandidateSet.begin(),
                                 CandEnd = CandidateSet.end();
     Cand != CandEnd; ++Cand)
  if (Cand->Function) {
    Fns.erase(Cand->Function);
    if (FunctionTemplateDecl *FunTmpl = Cand->Function->getPrimaryTemplate())
      Fns.erase(FunTmpl);
  }

// For each of the ADL candidates we found, add it to the overload
// set.
for (ADLResult::iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
  DeclAccessPair FoundDecl = DeclAccessPair::make(*I, AS_none);

  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
    if (ExplicitTemplateArgs)
      continue;

    AddOverloadCandidate(
        FD, FoundDecl, Args, CandidateSet, /*SuppressUserConversions=*/false,
        PartialOverloading, /*AllowExplicit=*/true,
        /*AllowExplicitConversions=*/false, ADLCallKind::UsesADL);
    if (CandidateSet.getRewriteInfo().shouldAddReversed(Context, FD)) {
      AddOverloadCandidate(
          FD, FoundDecl, {Args[1], Args[0]}, CandidateSet,
          /*SuppressUserConversions=*/false, PartialOverloading,
          /*AllowExplicit=*/true, /*AllowExplicitConversions=*/false,
          ADLCallKind::UsesADL, None, OverloadCandidateParamOrder::Reversed);
    }
  } else {
    auto *FTD = cast<FunctionTemplateDecl>(*I);
    AddTemplateOverloadCandidate(
        FTD, FoundDecl, ExplicitTemplateArgs, Args, CandidateSet,
        /*SuppressUserConversions=*/false, PartialOverloading,
        /*AllowExplicit=*/true, ADLCallKind::UsesADL);
    if (CandidateSet.getRewriteInfo().shouldAddReversed(
            Context, FTD->getTemplatedDecl())) {
      AddTemplateOverloadCandidate(
          FTD, FoundDecl, ExplicitTemplateArgs, {Args[1], Args[0]},
          CandidateSet, /*SuppressUserConversions=*/false, PartialOverloading,
          /*AllowExplicit=*/true, ADLCallKind::UsesADL,
          OverloadCandidateParamOrder::Reversed);
    }
  }
}
9380}

9382namespace {
9383enum class Comparison { Equal, Better, Worse };
9384}

9386/// Compares the enable_if attributes of two FunctionDecls, for the purposes of
9387/// overload resolution.
9388///
9389/// Cand1's set of enable_if attributes are said to be "better" than Cand2's iff
9390/// Cand1's first N enable_if attributes have precisely the same conditions as
9391/// Cand2's first N enable_if attributes (where N = the number of enable_if
9392/// attributes on Cand2), and Cand1 has more than N enable_if attributes.
9393///
9394/// Note that you can have a pair of candidates such that Cand1's enable_if
9395/// attributes are worse than Cand2's, and Cand2's enable_if attributes are
9396/// worse than Cand1's.
9397static Comparison compareEnableIfAttrs(const Sema &S, const FunctionDecl *Cand1,
                                     const FunctionDecl *Cand2) {
// Common case: One (or both) decls don't have enable_if attrs.
bool Cand1Attr = Cand1->hasAttr<EnableIfAttr>();
bool Cand2Attr = Cand2->hasAttr<EnableIfAttr>();
if (!Cand1Attr || !Cand2Attr) {
  if (Cand1Attr == Cand2Attr)
    return Comparison::Equal;
  return Cand1Attr ? Comparison::Better : Comparison::Worse;
}

auto Cand1Attrs = Cand1->specific_attrs<EnableIfAttr>();
auto Cand2Attrs = Cand2->specific_attrs<EnableIfAttr>();

llvm::FoldingSetNodeID Cand1ID, Cand2ID;
for (auto Pair : zip_longest(Cand1Attrs, Cand2Attrs)) {
  Optional<EnableIfAttr *> Cand1A = std::get<0>(Pair);
  Optional<EnableIfAttr *> Cand2A = std::get<1>(Pair);

  // It's impossible for Cand1 to be better than (or equal to) Cand2 if Cand1
  // has fewer enable_if attributes than Cand2, and vice versa.
  if (!Cand1A)
    return Comparison::Worse;
  if (!Cand2A)
    return Comparison::Better;

  Cand1ID.clear();
  Cand2ID.clear();

  (*Cand1A)->getCond()->Profile(Cand1ID, S.getASTContext(), true);
  (*Cand2A)->getCond()->Profile(Cand2ID, S.getASTContext(), true);
  if (Cand1ID != Cand2ID)
    return Comparison::Worse;
}

return Comparison::Equal;
9433}

9435static Comparison
9436isBetterMultiversionCandidate(const OverloadCandidate &Cand1,
                            const OverloadCandidate &Cand2) {
if (!Cand1.Function || !Cand1.Function->isMultiVersion() || !Cand2.Function ||
    !Cand2.Function->isMultiVersion())
  return Comparison::Equal;

// If both are invalid, they are equal. If one of them is invalid, the other
// is better.
if (Cand1.Function->isInvalidDecl()) {
  if (Cand2.Function->isInvalidDecl())
    return Comparison::Equal;
  return Comparison::Worse;
}
if (Cand2.Function->isInvalidDecl())
  return Comparison::Better;

// If this is a cpu_dispatch/cpu_specific multiversion situation, prefer
// cpu_dispatch, else arbitrarily based on the identifiers.
bool Cand1CPUDisp = Cand1.Function->hasAttr<CPUDispatchAttr>();
bool Cand2CPUDisp = Cand2.Function->hasAttr<CPUDispatchAttr>();
const auto *Cand1CPUSpec = Cand1.Function->getAttr<CPUSpecificAttr>();
const auto *Cand2CPUSpec = Cand2.Function->getAttr<CPUSpecificAttr>();

if (!Cand1CPUDisp && !Cand2CPUDisp && !Cand1CPUSpec && !Cand2CPUSpec)
  return Comparison::Equal;

if (Cand1CPUDisp && !Cand2CPUDisp)
  return Comparison::Better;
if (Cand2CPUDisp && !Cand1CPUDisp)
  return Comparison::Worse;

if (Cand1CPUSpec && Cand2CPUSpec) {
  if (Cand1CPUSpec->cpus_size() != Cand2CPUSpec->cpus_size())
    return Cand1CPUSpec->cpus_size() < Cand2CPUSpec->cpus_size()
               ? Comparison::Better
               : Comparison::Worse;

  std::pair<CPUSpecificAttr::cpus_iterator, CPUSpecificAttr::cpus_iterator>
      FirstDiff = std::mismatch(
          Cand1CPUSpec->cpus_begin(), Cand1CPUSpec->cpus_end(),
          Cand2CPUSpec->cpus_begin(),
          [](const IdentifierInfo *LHS, const IdentifierInfo *RHS) {
            return LHS->getName() == RHS->getName();
          });

  assert(FirstDiff.first != Cand1CPUSpec->cpus_end() &&((void)0)
         "Two different cpu-specific versions should not have the same "((void)0)
         "identifier list, otherwise they'd be the same decl!")((void)0);
  return (*FirstDiff.first)->getName() < (*FirstDiff.second)->getName()
             ? Comparison::Better
             : Comparison::Worse;
}
llvm_unreachable("No way to get here unless both had cpu_dispatch")__builtin_unreachable();
9489}

9491/// Compute the type of the implicit object parameter for the given function,
9492/// if any. Returns None if there is no implicit object parameter, and a null
9493/// QualType if there is a 'matches anything' implicit object parameter.
9494static Optional<QualType> getImplicitObjectParamType(ASTContext &Context,
                                                   const FunctionDecl *F) {
if (!isa<CXXMethodDecl>(F) || isa<CXXConstructorDecl>(F))
  return llvm::None;

auto *M = cast<CXXMethodDecl>(F);
// Static member functions' object parameters match all types.
if (M->isStatic())
  return QualType();

QualType T = M->getThisObjectType();
if (M->getRefQualifier() == RQ_RValue)
  return Context.getRValueReferenceType(T);
return Context.getLValueReferenceType(T);
9508}

9510static bool haveSameParameterTypes(ASTContext &Context, const FunctionDecl *F1,
                                 const FunctionDecl *F2, unsigned NumParams) {
if (declaresSameEntity(F1, F2))
  return true;

auto NextParam = [&](const FunctionDecl *F, unsigned &I, bool First) {
  if (First) {
    if (Optional<QualType> T = getImplicitObjectParamType(Context, F))
      return *T;
  }
  assert(I < F->getNumParams())((void)0);
  return F->getParamDecl(I++)->getType();
};

unsigned I1 = 0, I2 = 0;
for (unsigned I = 0; I != NumParams; ++I) {
  QualType T1 = NextParam(F1, I1, I == 0);
  QualType T2 = NextParam(F2, I2, I == 0);
  if (!T1.isNull() && !T1.isNull() && !Context.hasSameUnqualifiedType(T1, T2))
    return false;
}
return true;
9532}

9534/// isBetterOverloadCandidate - Determines whether the first overload
9535/// candidate is a better candidate than the second (C++ 13.3.3p1).
9536bool clang::isBetterOverloadCandidate(
  Sema &S, const OverloadCandidate &Cand1, const OverloadCandidate &Cand2,
  SourceLocation Loc, OverloadCandidateSet::CandidateSetKind Kind) {
// Define viable functions to be better candidates than non-viable
// functions.
if (!Cand2.Viable)
1
Assuming field 'Viable' is true→
2
←
Taking false branch→
  return Cand1.Viable;
else if (!Cand1.Viable)
3
←
Assuming field 'Viable' is true→
4
←
Taking false branch→
  return false;

// [CUDA] A function with 'never' preference is marked not viable, therefore
// is never shown up here. The worst preference shown up here is 'wrong side',
// e.g. an H function called by a HD function in device compilation. This is
// valid AST as long as the HD function is not emitted, e.g. it is an inline
// function which is called only by an H function. A deferred diagnostic will
// be triggered if it is emitted. However a wrong-sided function is still
// a viable candidate here.
//
// If Cand1 can be emitted and Cand2 cannot be emitted in the current
// context, Cand1 is better than Cand2. If Cand1 can not be emitted and Cand2
// can be emitted, Cand1 is not better than Cand2. This rule should have
// precedence over other rules.
//
// If both Cand1 and Cand2 can be emitted, or neither can be emitted, then
// other rules should be used to determine which is better. This is because
// host/device based overloading resolution is mostly for determining
// viability of a function. If two functions are both viable, other factors
// should take precedence in preference, e.g. the standard-defined preferences
// like argument conversion ranks or enable_if partial-ordering. The
// preference for pass-object-size parameters is probably most similar to a
// type-based-overloading decision and so should take priority.
//
// If other rules cannot determine which is better, CUDA preference will be
// used again to determine which is better.
//
// TODO: Currently IdentifyCUDAPreference does not return correct values
// for functions called in global variable initializers due to missing
// correct context about device/host. Therefore we can only enforce this
// rule when there is a caller. We should enforce this rule for functions
// in global variable initializers once proper context is added.
//
// TODO: We can only enable the hostness based overloading resolution when
// -fgpu-exclude-wrong-side-overloads is on since this requires deferring
// overloading resolution diagnostics.
if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function &&
5
←
Assuming field 'CUDA' is 0→
    S.getLangOpts().GPUExcludeWrongSideOverloads) {
  if (FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext)) {
    bool IsCallerImplicitHD = Sema::isCUDAImplicitHostDeviceFunction(Caller);
    bool IsCand1ImplicitHD =
        Sema::isCUDAImplicitHostDeviceFunction(Cand1.Function);
    bool IsCand2ImplicitHD =
        Sema::isCUDAImplicitHostDeviceFunction(Cand2.Function);
    auto P1 = S.IdentifyCUDAPreference(Caller, Cand1.Function);
    auto P2 = S.IdentifyCUDAPreference(Caller, Cand2.Function);
    assert(P1 != Sema::CFP_Never && P2 != Sema::CFP_Never)((void)0);
    // The implicit HD function may be a function in a system header which
    // is forced by pragma. In device compilation, if we prefer HD candidates
    // over wrong-sided candidates, overloading resolution may change, which
    // may result in non-deferrable diagnostics. As a workaround, we let
    // implicit HD candidates take equal preference as wrong-sided candidates.
    // This will preserve the overloading resolution.
    // TODO: We still need special handling of implicit HD functions since
    // they may incur other diagnostics to be deferred. We should make all
    // host/device related diagnostics deferrable and remove special handling
    // of implicit HD functions.
    auto EmitThreshold =
        (S.getLangOpts().CUDAIsDevice && IsCallerImplicitHD &&
         (IsCand1ImplicitHD || IsCand2ImplicitHD))
            ? Sema::CFP_Never
            : Sema::CFP_WrongSide;
    auto Cand1Emittable = P1 > EmitThreshold;
    auto Cand2Emittable = P2 > EmitThreshold;
    if (Cand1Emittable && !Cand2Emittable)
      return true;
    if (!Cand1Emittable && Cand2Emittable)
      return false;
  }
}

// C++ [over.match.best]p1:
//
//   -- if F is a static member function, ICS1(F) is defined such
//      that ICS1(F) is neither better nor worse than ICS1(G) for
//      any function G, and, symmetrically, ICS1(G) is neither
//      better nor worse than ICS1(F).
unsigned StartArg = 0;
if (Cand1.IgnoreObjectArgument || Cand2.IgnoreObjectArgument)
6
←
Assuming field 'IgnoreObjectArgument' is false→
7
←
Assuming field 'IgnoreObjectArgument' is false→
8
←
Taking false branch→
  StartArg = 1;

auto IsIllFormedConversion = [&](const ImplicitConversionSequence &ICS) {
  // We don't allow incompatible pointer conversions in C++.
  if (!S.getLangOpts().CPlusPlus)
    return ICS.isStandard() &&
           ICS.Standard.Second == ICK_Incompatible_Pointer_Conversion;

  // The only ill-formed conversion we allow in C++ is the string literal to
  // char* conversion, which is only considered ill-formed after C++11.
  return S.getLangOpts().CPlusPlus11 && !S.getLangOpts().WritableStrings &&
         hasDeprecatedStringLiteralToCharPtrConversion(ICS);
};

// Define functions that don't require ill-formed conversions for a given
// argument to be better candidates than functions that do.
unsigned NumArgs = Cand1.Conversions.size();
assert(Cand2.Conversions.size() == NumArgs && "Overload candidate mismatch")((void)0);
bool HasBetterConversion = false;
for (unsigned ArgIdx = StartArg; ArgIdx < NumArgs; ++ArgIdx) {
9
←
Assuming 'ArgIdx' is >= 'NumArgs'→
10
←
Loop condition is false. Execution continues on line 9652→
  bool Cand1Bad = IsIllFormedConversion(Cand1.Conversions[ArgIdx]);
  bool Cand2Bad = IsIllFormedConversion(Cand2.Conversions[ArgIdx]);
  if (Cand1Bad != Cand2Bad) {
    if (Cand1Bad)
      return false;
    HasBetterConversion = true;
  }
}

if (HasBetterConversion10.1
'HasBetterConversion' is false
)
11
←
Taking false branch→
  return true;

// C++ [over.match.best]p1:
//   A viable function F1 is defined to be a better function than another
//   viable function F2 if for all arguments i, ICSi(F1) is not a worse
//   conversion sequence than ICSi(F2), and then...
bool HasWorseConversion = false;
for (unsigned ArgIdx = StartArg; ArgIdx < NumArgs; ++ArgIdx) {
12
←
Loop condition is false. Execution continues on line 9701→
  switch (CompareImplicitConversionSequences(S, Loc,
                                             Cand1.Conversions[ArgIdx],
                                             Cand2.Conversions[ArgIdx])) {
  case ImplicitConversionSequence::Better:
    // Cand1 has a better conversion sequence.
    HasBetterConversion = true;
    break;

  case ImplicitConversionSequence::Worse:
    if (Cand1.Function && Cand2.Function &&
        Cand1.isReversed() != Cand2.isReversed() &&
        haveSameParameterTypes(S.Context, Cand1.Function, Cand2.Function,
                               NumArgs)) {
      // Work around large-scale breakage caused by considering reversed
      // forms of operator== in C++20:
      //
      // When comparing a function against a reversed function with the same
      // parameter types, if we have a better conversion for one argument and
      // a worse conversion for the other, the implicit conversion sequences
      // are treated as being equally good.
      //
      // This prevents a comparison function from being considered ambiguous
      // with a reversed form that is written in the same way.
      //
      // We diagnose this as an extension from CreateOverloadedBinOp.
      HasWorseConversion = true;
      break;
    }

    // Cand1 can't be better than Cand2.
    return false;

  case ImplicitConversionSequence::Indistinguishable:
    // Do nothing.
    break;
  }
}

//    -- for some argument j, ICSj(F1) is a better conversion sequence than
//       ICSj(F2), or, if not that,
if (HasBetterConversion12.1
'HasBetterConversion' is false
 && !HasWorseConversion)
  return true;

//   -- the context is an initialization by user-defined conversion
//      (see 8.5, 13.3.1.5) and the standard conversion sequence
//      from the return type of F1 to the destination type (i.e.,
//      the type of the entity being initialized) is a better
//      conversion sequence than the standard conversion sequence
//      from the return type of F2 to the destination type.
if (Kind == OverloadCandidateSet::CSK_InitByUserDefinedConversion &&
13
←
Assuming 'Kind' is not equal to CSK_InitByUserDefinedConversion→
    Cand1.Function && Cand2.Function &&
    isa<CXXConversionDecl>(Cand1.Function) &&
    isa<CXXConversionDecl>(Cand2.Function)) {
  // First check whether we prefer one of the conversion functions over the
  // other. This only distinguishes the results in non-standard, extension
  // cases such as the conversion from a lambda closure type to a function
  // pointer or block.
  ImplicitConversionSequence::CompareKind Result =
      compareConversionFunctions(S, Cand1.Function, Cand2.Function);
  if (Result == ImplicitConversionSequence::Indistinguishable)
    Result = CompareStandardConversionSequences(S, Loc,
                                                Cand1.FinalConversion,
                                                Cand2.FinalConversion);

  if (Result != ImplicitConversionSequence::Indistinguishable)
    return Result == ImplicitConversionSequence::Better;

  // FIXME: Compare kind of reference binding if conversion functions
  // convert to a reference type used in direct reference binding, per
  // C++14 [over.match.best]p1 section 2 bullet 3.
}

// FIXME: Work around a defect in the C++17 guaranteed copy elision wording,
// as combined with the resolution to CWG issue 243.
//
// When the context is initialization by constructor ([over.match.ctor] or
// either phase of [over.match.list]), a constructor is preferred over
// a conversion function.
if (Kind == OverloadCandidateSet::CSK_InitByConstructor && NumArgs == 1 &&
14
←
Assuming 'Kind' is not equal to CSK_InitByConstructor→
    Cand1.Function && Cand2.Function &&
    isa<CXXConstructorDecl>(Cand1.Function) !=
        isa<CXXConstructorDecl>(Cand2.Function))
  return isa<CXXConstructorDecl>(Cand1.Function);

//    -- F1 is a non-template function and F2 is a function template
//       specialization, or, if not that,
bool Cand1IsSpecialization = Cand1.Function &&
15
←
Assuming field 'Function' is null→
                             Cand1.Function->getPrimaryTemplate();
bool Cand2IsSpecialization = Cand2.Function &&
16
←
Assuming field 'Function' is null→
                             Cand2.Function->getPrimaryTemplate();
if (Cand1IsSpecialization16.1
'Cand1IsSpecialization' is equal to 'Cand2IsSpecialization'
 != Cand2IsSpecialization)
17
←
Taking false branch→
  return Cand2IsSpecialization;

//   -- F1 and F2 are function template specializations, and the function
//      template for F1 is more specialized than the template for F2
//      according to the partial ordering rules described in 14.5.5.2, or,
//      if not that,
if (Cand1IsSpecialization17.1
'Cand1IsSpecialization' is false
 && Cand2IsSpecialization) {
  if (FunctionTemplateDecl *BetterTemplate = S.getMoreSpecializedTemplate(
          Cand1.Function->getPrimaryTemplate(),
          Cand2.Function->getPrimaryTemplate(), Loc,
          isa<CXXConversionDecl>(Cand1.Function) ? TPOC_Conversion
                                                 : TPOC_Call,
          Cand1.ExplicitCallArguments, Cand2.ExplicitCallArguments,
          Cand1.isReversed() ^ Cand2.isReversed()))
    return BetterTemplate == Cand1.Function->getPrimaryTemplate();
}

//   -— F1 and F2 are non-template functions with the same
//      parameter-type-lists, and F1 is more constrained than F2 [...],
if (Cand1.Function17.2
Field 'Function' is null
 && Cand2.Function && !Cand1IsSpecialization &&
    !Cand2IsSpecialization && Cand1.Function->hasPrototype() &&
    Cand2.Function->hasPrototype()) {
  auto *PT1 = cast<FunctionProtoType>(Cand1.Function->getFunctionType());
  auto *PT2 = cast<FunctionProtoType>(Cand2.Function->getFunctionType());
  if (PT1->getNumParams() == PT2->getNumParams() &&
      PT1->isVariadic() == PT2->isVariadic() &&
      S.FunctionParamTypesAreEqual(PT1, PT2)) {
    Expr *RC1 = Cand1.Function->getTrailingRequiresClause();
    Expr *RC2 = Cand2.Function->getTrailingRequiresClause();
    if (RC1 && RC2) {
      bool AtLeastAsConstrained1, AtLeastAsConstrained2;
      if (S.IsAtLeastAsConstrained(Cand1.Function, {RC1}, Cand2.Function,
                                   {RC2}, AtLeastAsConstrained1) ||
          S.IsAtLeastAsConstrained(Cand2.Function, {RC2}, Cand1.Function,
                                   {RC1}, AtLeastAsConstrained2))
        return false;
      if (AtLeastAsConstrained1 != AtLeastAsConstrained2)
        return AtLeastAsConstrained1;
    } else if (RC1 || RC2) {
      return RC1 != nullptr;
    }
  }
}

//   -- F1 is a constructor for a class D, F2 is a constructor for a base
//      class B of D, and for all arguments the corresponding parameters of
//      F1 and F2 have the same type.
// FIXME: Implement the "all parameters have the same type" check.
bool Cand1IsInherited =
    dyn_cast_or_null<ConstructorUsingShadowDecl>(Cand1.FoundDecl.getDecl());
18
←
Assuming the object is a 'ConstructorUsingShadowDecl'→
bool Cand2IsInherited =
    dyn_cast_or_null<ConstructorUsingShadowDecl>(Cand2.FoundDecl.getDecl());
19
←
Assuming the object is a 'ConstructorUsingShadowDecl'→
if (Cand1IsInherited != Cand2IsInherited)
20
←
Assuming 'Cand1IsInherited' is equal to 'Cand2IsInherited'→
21
←
Taking false branch→
  return Cand2IsInherited;
else if (Cand1IsInherited) {
22
←
Assuming 'Cand1IsInherited' is true→
23
←
Taking true branch→
  assert(Cand2IsInherited)((void)0);
  auto *Cand1Class = cast<CXXRecordDecl>(Cand1.Function->getDeclContext());
24
←
Called C++ object pointer is null
  auto *Cand2Class = cast<CXXRecordDecl>(Cand2.Function->getDeclContext());
  if (Cand1Class->isDerivedFrom(Cand2Class))
    return true;
  if (Cand2Class->isDerivedFrom(Cand1Class))
    return false;
  // Inherited from sibling base classes: still ambiguous.
}

//   -- F2 is a rewritten candidate (12.4.1.2) and F1 is not
//   -- F1 and F2 are rewritten candidates, and F2 is a synthesized candidate
//      with reversed order of parameters and F1 is not
//
// We rank reversed + different operator as worse than just reversed, but
// that comparison can never happen, because we only consider reversing for
// the maximally-rewritten operator (== or <=>).
if (Cand1.RewriteKind != Cand2.RewriteKind)
  return Cand1.RewriteKind < Cand2.RewriteKind;

// Check C++17 tie-breakers for deduction guides.
{
  auto *Guide1 = dyn_cast_or_null<CXXDeductionGuideDecl>(Cand1.Function);
  auto *Guide2 = dyn_cast_or_null<CXXDeductionGuideDecl>(Cand2.Function);
  if (Guide1 && Guide2) {
    //  -- F1 is generated from a deduction-guide and F2 is not
    if (Guide1->isImplicit() != Guide2->isImplicit())
      return Guide2->isImplicit();

    //  -- F1 is the copy deduction candidate(16.3.1.8) and F2 is not
    if (Guide1->isCopyDeductionCandidate())
      return true;
  }
}

// Check for enable_if value-based overload resolution.
if (Cand1.Function && Cand2.Function) {
  Comparison Cmp = compareEnableIfAttrs(S, Cand1.Function, Cand2.Function);
  if (Cmp != Comparison::Equal)
    return Cmp == Comparison::Better;
}

bool HasPS1 = Cand1.Function != nullptr &&
              functionHasPassObjectSizeParams(Cand1.Function);
bool HasPS2 = Cand2.Function != nullptr &&
              functionHasPassObjectSizeParams(Cand2.Function);
if (HasPS1 != HasPS2 && HasPS1)
  return true;

auto MV = isBetterMultiversionCandidate(Cand1, Cand2);
if (MV == Comparison::Better)
  return true;
if (MV == Comparison::Worse)
  return false;

// If other rules cannot determine which is better, CUDA preference is used
// to determine which is better.
if (S.getLangOpts().CUDA && Cand1.Function && Cand2.Function) {
  FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext);
  return S.IdentifyCUDAPreference(Caller, Cand1.Function) >
         S.IdentifyCUDAPreference(Caller, Cand2.Function);
}

// General member function overloading is handled above, so this only handles
// constructors with address spaces.
// This only handles address spaces since C++ has no other
// qualifier that can be used with constructors.
const auto *CD1 = dyn_cast_or_null<CXXConstructorDecl>(Cand1.Function);
const auto *CD2 = dyn_cast_or_null<CXXConstructorDecl>(Cand2.Function);
if (CD1 && CD2) {
  LangAS AS1 = CD1->getMethodQualifiers().getAddressSpace();
  LangAS AS2 = CD2->getMethodQualifiers().getAddressSpace();
  if (AS1 != AS2) {
    if (Qualifiers::isAddressSpaceSupersetOf(AS2, AS1))
      return true;
    if (Qualifiers::isAddressSpaceSupersetOf(AS2, AS1))
      return false;
  }
}

return false;
9888}

9890/// Determine whether two declarations are "equivalent" for the purposes of
9891/// name lookup and overload resolution. This applies when the same internal/no
9892/// linkage entity is defined by two modules (probably by textually including
9893/// the same header). In such a case, we don't consider the declarations to
9894/// declare the same entity, but we also don't want lookups with both
9895/// declarations visible to be ambiguous in some cases (this happens when using
9896/// a modularized libstdc++).
9897bool Sema::isEquivalentInternalLinkageDeclaration(const NamedDecl *A,
                                                const NamedDecl *B) {
auto *VA = dyn_cast_or_null<ValueDecl>(A);
auto *VB = dyn_cast_or_null<ValueDecl>(B);
if (!VA || !VB)
  return false;

// The declarations must be declaring the same name as an internal linkage
// entity in different modules.
if (!VA->getDeclContext()->getRedeclContext()->Equals(
        VB->getDeclContext()->getRedeclContext()) ||
    getOwningModule(VA) == getOwningModule(VB) ||
    VA->isExternallyVisible() || VB->isExternallyVisible())
  return false;

// Check that the declarations appear to be equivalent.
//
// FIXME: Checking the type isn't really enough to resolve the ambiguity.
// For constants and functions, we should check the initializer or body is
// the same. For non-constant variables, we shouldn't allow it at all.
if (Context.hasSameType(VA->getType(), VB->getType()))
  return true;

// Enum constants within unnamed enumerations will have different types, but
// may still be similar enough to be interchangeable for our purposes.
if (auto *EA = dyn_cast<EnumConstantDecl>(VA)) {
  if (auto *EB = dyn_cast<EnumConstantDecl>(VB)) {
    // Only handle anonymous enums. If the enumerations were named and
    // equivalent, they would have been merged to the same type.
    auto *EnumA = cast<EnumDecl>(EA->getDeclContext());
    auto *EnumB = cast<EnumDecl>(EB->getDeclContext());
    if (EnumA->hasNameForLinkage() || EnumB->hasNameForLinkage() ||
        !Context.hasSameType(EnumA->getIntegerType(),
                             EnumB->getIntegerType()))
      return false;
    // Allow this only if the value is the same for both enumerators.
    return llvm::APSInt::isSameValue(EA->getInitVal(), EB->getInitVal());
  }
}

// Nothing else is sufficiently similar.
return false;
9939}

9941void Sema::diagnoseEquivalentInternalLinkageDeclarations(
  SourceLocation Loc, const NamedDecl *D, ArrayRef<const NamedDecl *> Equiv) {
assert(D && "Unknown declaration")((void)0);
Diag(Loc, diag::ext_equivalent_internal_linkage_decl_in_modules) << D;

Module *M = getOwningModule(D);
Diag(D->getLocation(), diag::note_equivalent_internal_linkage_decl)
    << !M << (M ? M->getFullModuleName() : "");

for (auto *E : Equiv) {
  Module *M = getOwningModule(E);
  Diag(E->getLocation(), diag::note_equivalent_internal_linkage_decl)
      << !M << (M ? M->getFullModuleName() : "");
}
9955}

9957/// Computes the best viable function (C++ 13.3.3)
9958/// within an overload candidate set.
9959///
9960/// \param Loc The location of the function name (or operator symbol) for
9961/// which overload resolution occurs.
9962///
9963/// \param Best If overload resolution was successful or found a deleted
9964/// function, \p Best points to the candidate function found.
9965///
9966/// \returns The result of overload resolution.
9967OverloadingResult
9968OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc,
                                       iterator &Best) {
llvm::SmallVector<OverloadCandidate *, 16> Candidates;
std::transform(begin(), end(), std::back_inserter(Candidates),
               [](OverloadCandidate &Cand) { return &Cand; });

// [CUDA] HD->H or HD->D calls are technically not allowed by CUDA but
// are accepted by both clang and NVCC. However, during a particular
// compilation mode only one call variant is viable. We need to
// exclude non-viable overload candidates from consideration based
// only on their host/device attributes. Specifically, if one
// candidate call is WrongSide and the other is SameSide, we ignore
// the WrongSide candidate.
// We only need to remove wrong-sided candidates here if
// -fgpu-exclude-wrong-side-overloads is off. When
// -fgpu-exclude-wrong-side-overloads is on, all candidates are compared
// uniformly in isBetterOverloadCandidate.
if (S.getLangOpts().CUDA && !S.getLangOpts().GPUExcludeWrongSideOverloads) {
  const FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext);
  bool ContainsSameSideCandidate =
      llvm::any_of(Candidates, [&](OverloadCandidate *Cand) {
        // Check viable function only.
        return Cand->Viable && Cand->Function &&
               S.IdentifyCUDAPreference(Caller, Cand->Function) ==
                   Sema::CFP_SameSide;
      });
  if (ContainsSameSideCandidate) {
    auto IsWrongSideCandidate = [&](OverloadCandidate *Cand) {
      // Check viable function only to avoid unnecessary data copying/moving.
      return Cand->Viable && Cand->Function &&
             S.IdentifyCUDAPreference(Caller, Cand->Function) ==
                 Sema::CFP_WrongSide;
    };
    llvm::erase_if(Candidates, IsWrongSideCandidate);
  }
}

// Find the best viable function.
Best = end();
for (auto *Cand : Candidates) {
  Cand->Best = false;
  if (Cand->Viable)
    if (Best == end() ||
        isBetterOverloadCandidate(S, *Cand, *Best, Loc, Kind))
      Best = Cand;
}

// If we didn't find any viable functions, abort.
if (Best == end())
  return OR_No_Viable_Function;

llvm::SmallVector<const NamedDecl *, 4> EquivalentCands;

llvm::SmallVector<OverloadCandidate*, 4> PendingBest;
PendingBest.push_back(&*Best);
Best->Best = true;

// Make sure that this function is better than every other viable
// function. If not, we have an ambiguity.
while (!PendingBest.empty()) {
  auto *Curr = PendingBest.pop_back_val();
  for (auto *Cand : Candidates) {
    if (Cand->Viable && !Cand->Best &&
        !isBetterOverloadCandidate(S, *Curr, *Cand, Loc, Kind)) {
      PendingBest.push_back(Cand);
      Cand->Best = true;

      if (S.isEquivalentInternalLinkageDeclaration(Cand->Function,
                                                   Curr->Function))
        EquivalentCands.push_back(Cand->Function);
      else
        Best = end();
    }
  }
}

// If we found more than one best candidate, this is ambiguous.
if (Best == end())
  return OR_Ambiguous;

// Best is the best viable function.
if (Best->Function && Best->Function->isDeleted())
  return OR_Deleted;

if (!EquivalentCands.empty())
  S.diagnoseEquivalentInternalLinkageDeclarations(Loc, Best->Function,
                                                  EquivalentCands);

return OR_Success;
10057}

10059namespace {

10061enum OverloadCandidateKind {
oc_function,
oc_method,
oc_reversed_binary_operator,
oc_constructor,
oc_implicit_default_constructor,
oc_implicit_copy_constructor,
oc_implicit_move_constructor,
oc_implicit_copy_assignment,
oc_implicit_move_assignment,
oc_implicit_equality_comparison,
oc_inherited_constructor
10073};

10075enum OverloadCandidateSelect {
ocs_non_template,
ocs_template,
ocs_described_template,
10079};

10081static std::pair<OverloadCandidateKind, OverloadCandidateSelect>
10082ClassifyOverloadCandidate(Sema &S, NamedDecl *Found, FunctionDecl *Fn,
                        OverloadCandidateRewriteKind CRK,
                        std::string &Description) {

bool isTemplate = Fn->isTemplateDecl() || Found->isTemplateDecl();
if (FunctionTemplateDecl *FunTmpl = Fn->getPrimaryTemplate()) {
  isTemplate = true;
  Description = S.getTemplateArgumentBindingsText(
      FunTmpl->getTemplateParameters(), *Fn->getTemplateSpecializationArgs());
}

OverloadCandidateSelect Select = [&]() {
  if (!Description.empty())
    return ocs_described_template;
  return isTemplate ? ocs_template : ocs_non_template;
}();

OverloadCandidateKind Kind = [&]() {
  if (Fn->isImplicit() && Fn->getOverloadedOperator() == OO_EqualEqual)
    return oc_implicit_equality_comparison;

  if (CRK & CRK_Reversed)
    return oc_reversed_binary_operator;

  if (CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(Fn)) {
    if (!Ctor->isImplicit()) {
      if (isa<ConstructorUsingShadowDecl>(Found))
        return oc_inherited_constructor;
      else
        return oc_constructor;
    }

    if (Ctor->isDefaultConstructor())
      return oc_implicit_default_constructor;

    if (Ctor->isMoveConstructor())
      return oc_implicit_move_constructor;

    assert(Ctor->isCopyConstructor() &&((void)0)
           "unexpected sort of implicit constructor")((void)0);
    return oc_implicit_copy_constructor;
  }

  if (CXXMethodDecl *Meth = dyn_cast<CXXMethodDecl>(Fn)) {
    // This actually gets spelled 'candidate function' for now, but
    // it doesn't hurt to split it out.
    if (!Meth->isImplicit())
      return oc_method;

    if (Meth->isMoveAssignmentOperator())
      return oc_implicit_move_assignment;

    if (Meth->isCopyAssignmentOperator())
      return oc_implicit_copy_assignment;

    assert(isa<CXXConversionDecl>(Meth) && "expected conversion")((void)0);
    return oc_method;
  }

  return oc_function;
}();

return std::make_pair(Kind, Select);
10145}

10147void MaybeEmitInheritedConstructorNote(Sema &S, Decl *FoundDecl) {
// FIXME: It'd be nice to only emit a note once per using-decl per overload
// set.
if (auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(FoundDecl))
  S.Diag(FoundDecl->getLocation(),
         diag::note_ovl_candidate_inherited_constructor)
    << Shadow->getNominatedBaseClass();
10154}

10156} // end anonymous namespace

10158static bool isFunctionAlwaysEnabled(const ASTContext &Ctx,
                                  const FunctionDecl *FD) {
for (auto *EnableIf : FD->specific_attrs<EnableIfAttr>()) {
  bool AlwaysTrue;
  if (EnableIf->getCond()->isValueDependent() ||
      !EnableIf->getCond()->EvaluateAsBooleanCondition(AlwaysTrue, Ctx))
    return false;
  if (!AlwaysTrue)
    return false;
}
return true;
10169}

10171/// Returns true if we can take the address of the function.
10172///
10173/// \param Complain - If true, we'll emit a diagnostic
10174/// \param InOverloadResolution - For the purposes of emitting a diagnostic, are
10175///   we in overload resolution?
10176/// \param Loc - The location of the statement we're complaining about. Ignored
10177///   if we're not complaining, or if we're in overload resolution.
10178static bool checkAddressOfFunctionIsAvailable(Sema &S, const FunctionDecl *FD,
                                            bool Complain,
                                            bool InOverloadResolution,
                                            SourceLocation Loc) {
if (!isFunctionAlwaysEnabled(S.Context, FD)) {
  if (Complain) {
    if (InOverloadResolution)
      S.Diag(FD->getBeginLoc(),
             diag::note_addrof_ovl_candidate_disabled_by_enable_if_attr);
    else
      S.Diag(Loc, diag::err_addrof_function_disabled_by_enable_if_attr) << FD;
  }
  return false;
}

if (FD->getTrailingRequiresClause()) {
  ConstraintSatisfaction Satisfaction;
  if (S.CheckFunctionConstraints(FD, Satisfaction, Loc))
    return false;
  if (!Satisfaction.IsSatisfied) {
    if (Complain) {
      if (InOverloadResolution)
        S.Diag(FD->getBeginLoc(),
               diag::note_ovl_candidate_unsatisfied_constraints);
      else
        S.Diag(Loc, diag::err_addrof_function_constraints_not_satisfied)
            << FD;
      S.DiagnoseUnsatisfiedConstraint(Satisfaction);
    }
    return false;
  }
}

auto I = llvm::find_if(FD->parameters(), [](const ParmVarDecl *P) {
  return P->hasAttr<PassObjectSizeAttr>();
});
if (I == FD->param_end())
  return true;

if (Complain) {
  // Add one to ParamNo because it's user-facing
  unsigned ParamNo = std::distance(FD->param_begin(), I) + 1;
  if (InOverloadResolution)
    S.Diag(FD->getLocation(),
           diag::note_ovl_candidate_has_pass_object_size_params)
        << ParamNo;
  else
    S.Diag(Loc, diag::err_address_of_function_with_pass_object_size_params)
        << FD << ParamNo;
}
return false;
10229}

10231static bool checkAddressOfCandidateIsAvailable(Sema &S,
                                             const FunctionDecl *FD) {
return checkAddressOfFunctionIsAvailable(S, FD, /*Complain=*/true,
                                         /*InOverloadResolution=*/true,
                                         /*Loc=*/SourceLocation());
10236}

10238bool Sema::checkAddressOfFunctionIsAvailable(const FunctionDecl *Function,
                                           bool Complain,
                                           SourceLocation Loc) {
return ::checkAddressOfFunctionIsAvailable(*this, Function, Complain,
                                           /*InOverloadResolution=*/false,
                                           Loc);
10244}

10246// Don't print candidates other than the one that matches the calling
10247// convention of the call operator, since that is guaranteed to exist.
10248static bool shouldSkipNotingLambdaConversionDecl(FunctionDecl *Fn) {
const auto *ConvD = dyn_cast<CXXConversionDecl>(Fn);

if (!ConvD)
  return false;
const auto *RD = cast<CXXRecordDecl>(Fn->getParent());
if (!RD->isLambda())
  return false;

CXXMethodDecl *CallOp = RD->getLambdaCallOperator();
CallingConv CallOpCC =
    CallOp->getType()->castAs<FunctionType>()->getCallConv();
QualType ConvRTy = ConvD->getType()->castAs<FunctionType>()->getReturnType();
CallingConv ConvToCC =
    ConvRTy->getPointeeType()->castAs<FunctionType>()->getCallConv();

return ConvToCC != CallOpCC;
10265}

10267// Notes the location of an overload candidate.
10268void Sema::NoteOverloadCandidate(NamedDecl *Found, FunctionDecl *Fn,
                               OverloadCandidateRewriteKind RewriteKind,
                               QualType DestType, bool TakingAddress) {
if (TakingAddress && !checkAddressOfCandidateIsAvailable(*this, Fn))
  return;
if (Fn->isMultiVersion() && Fn->hasAttr<TargetAttr>() &&
    !Fn->getAttr<TargetAttr>()->isDefaultVersion())
  return;
if (shouldSkipNotingLambdaConversionDecl(Fn))
  return;

std::string FnDesc;
std::pair<OverloadCandidateKind, OverloadCandidateSelect> KSPair =
    ClassifyOverloadCandidate(*this, Found, Fn, RewriteKind, FnDesc);
PartialDiagnostic PD = PDiag(diag::note_ovl_candidate)
                       << (unsigned)KSPair.first << (unsigned)KSPair.second
                       << Fn << FnDesc;

HandleFunctionTypeMismatch(PD, Fn->getType(), DestType);
Diag(Fn->getLocation(), PD);
MaybeEmitInheritedConstructorNote(*this, Found);
10289}

10291static void
10292MaybeDiagnoseAmbiguousConstraints(Sema &S, ArrayRef<OverloadCandidate> Cands) {
// Perhaps the ambiguity was caused by two atomic constraints that are
// 'identical' but not equivalent:
//
// void foo() requires (sizeof(T) > 4) { } // #1
// void foo() requires (sizeof(T) > 4) && T::value { } // #2
//
// The 'sizeof(T) > 4' constraints are seemingly equivalent and should cause
// #2 to subsume #1, but these constraint are not considered equivalent
// according to the subsumption rules because they are not the same
// source-level construct. This behavior is quite confusing and we should try
// to help the user figure out what happened.

SmallVector<const Expr *, 3> FirstAC, SecondAC;
FunctionDecl *FirstCand = nullptr, *SecondCand = nullptr;
for (auto I = Cands.begin(), E = Cands.end(); I != E; ++I) {
  if (!I->Function)
    continue;
  SmallVector<const Expr *, 3> AC;
  if (auto *Template = I->Function->getPrimaryTemplate())
    Template->getAssociatedConstraints(AC);
  else
    I->Function->getAssociatedConstraints(AC);
  if (AC.empty())
    continue;
  if (FirstCand == nullptr) {
    FirstCand = I->Function;
    FirstAC = AC;
  } else if (SecondCand == nullptr) {
    SecondCand = I->Function;
    SecondAC = AC;
  } else {
    // We have more than one pair of constrained functions - this check is
    // expensive and we'd rather not try to diagnose it.
    return;
  }
}
if (!SecondCand)
  return;
// The diagnostic can only happen if there are associated constraints on
// both sides (there needs to be some identical atomic constraint).
if (S.MaybeEmitAmbiguousAtomicConstraintsDiagnostic(FirstCand, FirstAC,
                                                    SecondCand, SecondAC))
  // Just show the user one diagnostic, they'll probably figure it out
  // from here.
  return;
10338}

10340// Notes the location of all overload candidates designated through
10341// OverloadedExpr
10342void Sema::NoteAllOverloadCandidates(Expr *OverloadedExpr, QualType DestType,
                                   bool TakingAddress) {
assert(OverloadedExpr->getType() == Context.OverloadTy)((void)0);

OverloadExpr::FindResult Ovl = OverloadExpr::find(OverloadedExpr);
OverloadExpr *OvlExpr = Ovl.Expression;

for (UnresolvedSetIterator I = OvlExpr->decls_begin(),
                          IEnd = OvlExpr->decls_end();
     I != IEnd; ++I) {
  if (FunctionTemplateDecl *FunTmpl =
              dyn_cast<FunctionTemplateDecl>((*I)->getUnderlyingDecl()) ) {
    NoteOverloadCandidate(*I, FunTmpl->getTemplatedDecl(), CRK_None, DestType,
                          TakingAddress);
  } else if (FunctionDecl *Fun
                    = dyn_cast<FunctionDecl>((*I)->getUnderlyingDecl()) ) {
    NoteOverloadCandidate(*I, Fun, CRK_None, DestType, TakingAddress);
  }
}
10361}

10363/// Diagnoses an ambiguous conversion.  The partial diagnostic is the
10364/// "lead" diagnostic; it will be given two arguments, the source and
10365/// target types of the conversion.
10366void ImplicitConversionSequence::DiagnoseAmbiguousConversion(
                               Sema &S,
                               SourceLocation CaretLoc,
                               const PartialDiagnostic &PDiag) const {
S.Diag(CaretLoc, PDiag)
  << Ambiguous.getFromType() << Ambiguous.getToType();
unsigned CandsShown = 0;
AmbiguousConversionSequence::const_iterator I, E;
for (I = Ambiguous.begin(), E = Ambiguous.end(); I != E; ++I) {
  if (CandsShown >= S.Diags.getNumOverloadCandidatesToShow())
    break;
  ++CandsShown;
  S.NoteOverloadCandidate(I->first, I->second);
}
S.Diags.overloadCandidatesShown(CandsShown);
if (I != E)
  S.Diag(SourceLocation(), diag::note_ovl_too_many_candidates) << int(E - I);
10383}

10385static void DiagnoseBadConversion(Sema &S, OverloadCandidate *Cand,
                                unsigned I, bool TakingCandidateAddress) {
const ImplicitConversionSequence &Conv = Cand->Conversions[I];
assert(Conv.isBad())((void)0);
assert(Cand->Function && "for now, candidate must be a function")((void)0);
FunctionDecl *Fn = Cand->Function;

// There's a conversion slot for the object argument if this is a
// non-constructor method.  Note that 'I' corresponds the
// conversion-slot index.
bool isObjectArgument = false;
if (isa<CXXMethodDecl>(Fn) && !isa<CXXConstructorDecl>(Fn)) {
  if (I == 0)
    isObjectArgument = true;
  else
    I--;
}

std::string FnDesc;
std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
    ClassifyOverloadCandidate(S, Cand->FoundDecl, Fn, Cand->getRewriteKind(),
                              FnDesc);

Expr *FromExpr = Conv.Bad.FromExpr;
QualType FromTy = Conv.Bad.getFromType();
QualType ToTy = Conv.Bad.getToType();

if (FromTy == S.Context.OverloadTy) {
  assert(FromExpr && "overload set argument came from implicit argument?")((void)0);
  Expr *E = FromExpr->IgnoreParens();
  if (isa<UnaryOperator>(E))
    E = cast<UnaryOperator>(E)->getSubExpr()->IgnoreParens();
  DeclarationName Name = cast<OverloadExpr>(E)->getName();

  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_overload)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << ToTy
      << Name << I + 1;
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

// Do some hand-waving analysis to see if the non-viability is due
// to a qualifier mismatch.
CanQualType CFromTy = S.Context.getCanonicalType(FromTy);
CanQualType CToTy = S.Context.getCanonicalType(ToTy);
if (CanQual<ReferenceType> RT = CToTy->getAs<ReferenceType>())
  CToTy = RT->getPointeeType();
else {
  // TODO: detect and diagnose the full richness of const mismatches.
  if (CanQual<PointerType> FromPT = CFromTy->getAs<PointerType>())
    if (CanQual<PointerType> ToPT = CToTy->getAs<PointerType>()) {
      CFromTy = FromPT->getPointeeType();
      CToTy = ToPT->getPointeeType();
    }
}

if (CToTy.getUnqualifiedType() == CFromTy.getUnqualifiedType() &&
    !CToTy.isAtLeastAsQualifiedAs(CFromTy)) {
  Qualifiers FromQs = CFromTy.getQualifiers();
  Qualifiers ToQs = CToTy.getQualifiers();

  if (FromQs.getAddressSpace() != ToQs.getAddressSpace()) {
    if (isObjectArgument)
      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_addrspace_this)
          << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
          << FnDesc << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
          << FromQs.getAddressSpace() << ToQs.getAddressSpace();
    else
      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_addrspace)
          << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
          << FnDesc << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
          << FromQs.getAddressSpace() << ToQs.getAddressSpace()
          << ToTy->isReferenceType() << I + 1;
    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
    return;
  }

  if (FromQs.getObjCLifetime() != ToQs.getObjCLifetime()) {
    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_ownership)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
        << FromQs.getObjCLifetime() << ToQs.getObjCLifetime()
        << (unsigned)isObjectArgument << I + 1;
    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
    return;
  }

  if (FromQs.getObjCGCAttr() != ToQs.getObjCGCAttr()) {
    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_gc)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
        << FromQs.getObjCGCAttr() << ToQs.getObjCGCAttr()
        << (unsigned)isObjectArgument << I + 1;
    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
    return;
  }

  if (FromQs.hasUnaligned() != ToQs.hasUnaligned()) {
    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_unaligned)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
        << FromQs.hasUnaligned() << I + 1;
    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
    return;
  }

  unsigned CVR = FromQs.getCVRQualifiers() & ~ToQs.getCVRQualifiers();
  assert(CVR && "expected qualifiers mismatch")((void)0);

  if (isObjectArgument) {
    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_cvr_this)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
        << (CVR - 1);
  } else {
    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_cvr)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
        << (CVR - 1) << I + 1;
  }
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

if (Conv.Bad.Kind == BadConversionSequence::lvalue_ref_to_rvalue ||
    Conv.Bad.Kind == BadConversionSequence::rvalue_ref_to_lvalue) {
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_value_category)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (unsigned)isObjectArgument << I + 1
      << (Conv.Bad.Kind == BadConversionSequence::rvalue_ref_to_lvalue)
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange());
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

// Special diagnostic for failure to convert an initializer list, since
// telling the user that it has type void is not useful.
if (FromExpr && isa<InitListExpr>(FromExpr)) {
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_list_argument)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
      << ToTy << (unsigned)isObjectArgument << I + 1;
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

// Diagnose references or pointers to incomplete types differently,
// since it's far from impossible that the incompleteness triggered
// the failure.
QualType TempFromTy = FromTy.getNonReferenceType();
if (const PointerType *PTy = TempFromTy->getAs<PointerType>())
  TempFromTy = PTy->getPointeeType();
if (TempFromTy->isIncompleteType()) {
  // Emit the generic diagnostic and, optionally, add the hints to it.
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_conv_incomplete)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
      << ToTy << (unsigned)isObjectArgument << I + 1
      << (unsigned)(Cand->Fix.Kind);

  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

// Diagnose base -> derived pointer conversions.
unsigned BaseToDerivedConversion = 0;
if (const PointerType *FromPtrTy = FromTy->getAs<PointerType>()) {
  if (const PointerType *ToPtrTy = ToTy->getAs<PointerType>()) {
    if (ToPtrTy->getPointeeType().isAtLeastAsQualifiedAs(
                                             FromPtrTy->getPointeeType()) &&
        !FromPtrTy->getPointeeType()->isIncompleteType() &&
        !ToPtrTy->getPointeeType()->isIncompleteType() &&
        S.IsDerivedFrom(SourceLocation(), ToPtrTy->getPointeeType(),
                        FromPtrTy->getPointeeType()))
      BaseToDerivedConversion = 1;
  }
} else if (const ObjCObjectPointerType *FromPtrTy
                                  = FromTy->getAs<ObjCObjectPointerType>()) {
  if (const ObjCObjectPointerType *ToPtrTy
                                      = ToTy->getAs<ObjCObjectPointerType>())
    if (const ObjCInterfaceDecl *FromIface = FromPtrTy->getInterfaceDecl())
      if (const ObjCInterfaceDecl *ToIface = ToPtrTy->getInterfaceDecl())
        if (ToPtrTy->getPointeeType().isAtLeastAsQualifiedAs(
                                              FromPtrTy->getPointeeType()) &&
            FromIface->isSuperClassOf(ToIface))
          BaseToDerivedConversion = 2;
} else if (const ReferenceType *ToRefTy = ToTy->getAs<ReferenceType>()) {
  if (ToRefTy->getPointeeType().isAtLeastAsQualifiedAs(FromTy) &&
      !FromTy->isIncompleteType() &&
      !ToRefTy->getPointeeType()->isIncompleteType() &&
      S.IsDerivedFrom(SourceLocation(), ToRefTy->getPointeeType(), FromTy)) {
    BaseToDerivedConversion = 3;
  }
}

if (BaseToDerivedConversion) {
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_base_to_derived_conv)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
      << (BaseToDerivedConversion - 1) << FromTy << ToTy << I + 1;
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

if (isa<ObjCObjectPointerType>(CFromTy) &&
    isa<PointerType>(CToTy)) {
    Qualifiers FromQs = CFromTy.getQualifiers();
    Qualifiers ToQs = CToTy.getQualifiers();
    if (FromQs.getObjCLifetime() != ToQs.getObjCLifetime()) {
      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_bad_arc_conv)
          << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
          << FnDesc << (FromExpr ? FromExpr->getSourceRange() : SourceRange())
          << FromTy << ToTy << (unsigned)isObjectArgument << I + 1;
      MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
      return;
    }
}

if (TakingCandidateAddress &&
    !checkAddressOfCandidateIsAvailable(S, Cand->Function))
  return;

// Emit the generic diagnostic and, optionally, add the hints to it.
PartialDiagnostic FDiag = S.PDiag(diag::note_ovl_candidate_bad_conv);
FDiag << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
      << (FromExpr ? FromExpr->getSourceRange() : SourceRange()) << FromTy
      << ToTy << (unsigned)isObjectArgument << I + 1
      << (unsigned)(Cand->Fix.Kind);

// If we can fix the conversion, suggest the FixIts.
for (std::vector<FixItHint>::iterator HI = Cand->Fix.Hints.begin(),
     HE = Cand->Fix.Hints.end(); HI != HE; ++HI)
  FDiag << *HI;
S.Diag(Fn->getLocation(), FDiag);

MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
10622}

10624/// Additional arity mismatch diagnosis specific to a function overload
10625/// candidates. This is not covered by the more general DiagnoseArityMismatch()
10626/// over a candidate in any candidate set.
10627static bool CheckArityMismatch(Sema &S, OverloadCandidate *Cand,
                             unsigned NumArgs) {
FunctionDecl *Fn = Cand->Function;
unsigned MinParams = Fn->getMinRequiredArguments();

// With invalid overloaded operators, it's possible that we think we
// have an arity mismatch when in fact it looks like we have the
// right number of arguments, because only overloaded operators have
// the weird behavior of overloading member and non-member functions.
// Just don't report anything.
if (Fn->isInvalidDecl() &&
    Fn->getDeclName().getNameKind() == DeclarationName::CXXOperatorName)
  return true;

if (NumArgs < MinParams) {
  assert((Cand->FailureKind == ovl_fail_too_few_arguments) ||((void)0)
         (Cand->FailureKind == ovl_fail_bad_deduction &&((void)0)
          Cand->DeductionFailure.Result == Sema::TDK_TooFewArguments))((void)0);
} else {
  assert((Cand->FailureKind == ovl_fail_too_many_arguments) ||((void)0)
         (Cand->FailureKind == ovl_fail_bad_deduction &&((void)0)
          Cand->DeductionFailure.Result == Sema::TDK_TooManyArguments))((void)0);
}

return false;
10652}

10654/// General arity mismatch diagnosis over a candidate in a candidate set.
10655static void DiagnoseArityMismatch(Sema &S, NamedDecl *Found, Decl *D,
                                unsigned NumFormalArgs) {
assert(isa<FunctionDecl>(D) &&((void)0)
    "The templated declaration should at least be a function"((void)0)
    " when diagnosing bad template argument deduction due to too many"((void)0)
    " or too few arguments")((void)0);

FunctionDecl *Fn = cast<FunctionDecl>(D);

// TODO: treat calls to a missing default constructor as a special case
const auto *FnTy = Fn->getType()->castAs<FunctionProtoType>();
unsigned MinParams = Fn->getMinRequiredArguments();

// at least / at most / exactly
unsigned mode, modeCount;
if (NumFormalArgs < MinParams) {
  if (MinParams != FnTy->getNumParams() || FnTy->isVariadic() ||
      FnTy->isTemplateVariadic())
    mode = 0; // "at least"
  else
    mode = 2; // "exactly"
  modeCount = MinParams;
} else {
  if (MinParams != FnTy->getNumParams())
    mode = 1; // "at most"
  else
    mode = 2; // "exactly"
  modeCount = FnTy->getNumParams();
}

std::string Description;
std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
    ClassifyOverloadCandidate(S, Found, Fn, CRK_None, Description);

if (modeCount == 1 && Fn->getParamDecl(0)->getDeclName())
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_arity_one)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
      << Description << mode << Fn->getParamDecl(0) << NumFormalArgs;
else
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_arity)
      << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second
      << Description << mode << modeCount << NumFormalArgs;

MaybeEmitInheritedConstructorNote(S, Found);
10699}

10701/// Arity mismatch diagnosis specific to a function overload candidate.
10702static void DiagnoseArityMismatch(Sema &S, OverloadCandidate *Cand,
                                unsigned NumFormalArgs) {
if (!CheckArityMismatch(S, Cand, NumFormalArgs))
  DiagnoseArityMismatch(S, Cand->FoundDecl, Cand->Function, NumFormalArgs);
10706}

10708static TemplateDecl *getDescribedTemplate(Decl *Templated) {
if (TemplateDecl *TD = Templated->getDescribedTemplate())
  return TD;
llvm_unreachable("Unsupported: Getting the described template declaration"__builtin_unreachable()
                 " for bad deduction diagnosis")__builtin_unreachable();
10713}

10715/// Diagnose a failed template-argument deduction.
10716static void DiagnoseBadDeduction(Sema &S, NamedDecl *Found, Decl *Templated,
                               DeductionFailureInfo &DeductionFailure,
                               unsigned NumArgs,
                               bool TakingCandidateAddress) {
TemplateParameter Param = DeductionFailure.getTemplateParameter();
NamedDecl *ParamD;
(ParamD = Param.dyn_cast<TemplateTypeParmDecl*>()) ||
(ParamD = Param.dyn_cast<NonTypeTemplateParmDecl*>()) ||
(ParamD = Param.dyn_cast<TemplateTemplateParmDecl*>());
switch (DeductionFailure.Result) {
case Sema::TDK_Success:
  llvm_unreachable("TDK_success while diagnosing bad deduction")__builtin_unreachable();

case Sema::TDK_Incomplete: {
  assert(ParamD && "no parameter found for incomplete deduction result")((void)0);
  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_incomplete_deduction)
      << ParamD->getDeclName();
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
}

case Sema::TDK_IncompletePack: {
  assert(ParamD && "no parameter found for incomplete deduction result")((void)0);
  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_incomplete_deduction_pack)
      << ParamD->getDeclName()
      << (DeductionFailure.getFirstArg()->pack_size() + 1)
      << *DeductionFailure.getFirstArg();
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
}

case Sema::TDK_Underqualified: {
  assert(ParamD && "no parameter found for bad qualifiers deduction result")((void)0);
  TemplateTypeParmDecl *TParam = cast<TemplateTypeParmDecl>(ParamD);

  QualType Param = DeductionFailure.getFirstArg()->getAsType();

  // Param will have been canonicalized, but it should just be a
  // qualified version of ParamD, so move the qualifiers to that.
  QualifierCollector Qs;
  Qs.strip(Param);
  QualType NonCanonParam = Qs.apply(S.Context, TParam->getTypeForDecl());
  assert(S.Context.hasSameType(Param, NonCanonParam))((void)0);

  // Arg has also been canonicalized, but there's nothing we can do
  // about that.  It also doesn't matter as much, because it won't
  // have any template parameters in it (because deduction isn't
  // done on dependent types).
  QualType Arg = DeductionFailure.getSecondArg()->getAsType();

  S.Diag(Templated->getLocation(), diag::note_ovl_candidate_underqualified)
      << ParamD->getDeclName() << Arg << NonCanonParam;
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
}

case Sema::TDK_Inconsistent: {
  assert(ParamD && "no parameter found for inconsistent deduction result")((void)0);
  int which = 0;
  if (isa<TemplateTypeParmDecl>(ParamD))
    which = 0;
  else if (isa<NonTypeTemplateParmDecl>(ParamD)) {
    // Deduction might have failed because we deduced arguments of two
    // different types for a non-type template parameter.
    // FIXME: Use a different TDK value for this.
    QualType T1 =
        DeductionFailure.getFirstArg()->getNonTypeTemplateArgumentType();
    QualType T2 =
        DeductionFailure.getSecondArg()->getNonTypeTemplateArgumentType();
    if (!T1.isNull() && !T2.isNull() && !S.Context.hasSameType(T1, T2)) {
      S.Diag(Templated->getLocation(),
             diag::note_ovl_candidate_inconsistent_deduction_types)
        << ParamD->getDeclName() << *DeductionFailure.getFirstArg() << T1
        << *DeductionFailure.getSecondArg() << T2;
      MaybeEmitInheritedConstructorNote(S, Found);
      return;
    }

    which = 1;
  } else {
    which = 2;
  }

  // Tweak the diagnostic if the problem is that we deduced packs of
  // different arities. We'll print the actual packs anyway in case that
  // includes additional useful information.
  if (DeductionFailure.getFirstArg()->getKind() == TemplateArgument::Pack &&
      DeductionFailure.getSecondArg()->getKind() == TemplateArgument::Pack &&
      DeductionFailure.getFirstArg()->pack_size() !=
          DeductionFailure.getSecondArg()->pack_size()) {
    which = 3;
  }

  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_inconsistent_deduction)
      << which << ParamD->getDeclName() << *DeductionFailure.getFirstArg()
      << *DeductionFailure.getSecondArg();
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
}

case Sema::TDK_InvalidExplicitArguments:
  assert(ParamD && "no parameter found for invalid explicit arguments")((void)0);
  if (ParamD->getDeclName())
    S.Diag(Templated->getLocation(),
           diag::note_ovl_candidate_explicit_arg_mismatch_named)
        << ParamD->getDeclName();
  else {
    int index = 0;
    if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(ParamD))
      index = TTP->getIndex();
    else if (NonTypeTemplateParmDecl *NTTP
                                = dyn_cast<NonTypeTemplateParmDecl>(ParamD))
      index = NTTP->getIndex();
    else
      index = cast<TemplateTemplateParmDecl>(ParamD)->getIndex();
    S.Diag(Templated->getLocation(),
           diag::note_ovl_candidate_explicit_arg_mismatch_unnamed)
        << (index + 1);
  }
  MaybeEmitInheritedConstructorNote(S, Found);
  return;

case Sema::TDK_ConstraintsNotSatisfied: {
  // Format the template argument list into the argument string.
  SmallString<128> TemplateArgString;
  TemplateArgumentList *Args = DeductionFailure.getTemplateArgumentList();
  TemplateArgString = " ";
  TemplateArgString += S.getTemplateArgumentBindingsText(
      getDescribedTemplate(Templated)->getTemplateParameters(), *Args);
  if (TemplateArgString.size() == 1)
    TemplateArgString.clear();
  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_unsatisfied_constraints)
      << TemplateArgString;

  S.DiagnoseUnsatisfiedConstraint(
      static_cast<CNSInfo*>(DeductionFailure.Data)->Satisfaction);
  return;
}
case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
  DiagnoseArityMismatch(S, Found, Templated, NumArgs);
  return;

case Sema::TDK_InstantiationDepth:
  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_instantiation_depth);
  MaybeEmitInheritedConstructorNote(S, Found);
  return;

case Sema::TDK_SubstitutionFailure: {
  // Format the template argument list into the argument string.
  SmallString<128> TemplateArgString;
  if (TemplateArgumentList *Args =
          DeductionFailure.getTemplateArgumentList()) {
    TemplateArgString = " ";
    TemplateArgString += S.getTemplateArgumentBindingsText(
        getDescribedTemplate(Templated)->getTemplateParameters(), *Args);
    if (TemplateArgString.size() == 1)
      TemplateArgString.clear();
  }

  // If this candidate was disabled by enable_if, say so.
  PartialDiagnosticAt *PDiag = DeductionFailure.getSFINAEDiagnostic();
  if (PDiag && PDiag->second.getDiagID() ==
        diag::err_typename_nested_not_found_enable_if) {
    // FIXME: Use the source range of the condition, and the fully-qualified
    //        name of the enable_if template. These are both present in PDiag.
    S.Diag(PDiag->first, diag::note_ovl_candidate_disabled_by_enable_if)
      << "'enable_if'" << TemplateArgString;
    return;
  }

  // We found a specific requirement that disabled the enable_if.
  if (PDiag && PDiag->second.getDiagID() ==
      diag::err_typename_nested_not_found_requirement) {
    S.Diag(Templated->getLocation(),
           diag::note_ovl_candidate_disabled_by_requirement)
      << PDiag->second.getStringArg(0) << TemplateArgString;
    return;
  }

  // Format the SFINAE diagnostic into the argument string.
  // FIXME: Add a general mechanism to include a PartialDiagnostic *'s
  //        formatted message in another diagnostic.
  SmallString<128> SFINAEArgString;
  SourceRange R;
  if (PDiag) {
    SFINAEArgString = ": ";
    R = SourceRange(PDiag->first, PDiag->first);
    PDiag->second.EmitToString(S.getDiagnostics(), SFINAEArgString);
  }

  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_substitution_failure)
      << TemplateArgString << SFINAEArgString << R;
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
}

case Sema::TDK_DeducedMismatch:
case Sema::TDK_DeducedMismatchNested: {
  // Format the template argument list into the argument string.
  SmallString<128> TemplateArgString;
  if (TemplateArgumentList *Args =
          DeductionFailure.getTemplateArgumentList()) {
    TemplateArgString = " ";
    TemplateArgString += S.getTemplateArgumentBindingsText(
        getDescribedTemplate(Templated)->getTemplateParameters(), *Args);
    if (TemplateArgString.size() == 1)
      TemplateArgString.clear();
  }

  S.Diag(Templated->getLocation(), diag::note_ovl_candidate_deduced_mismatch)
      << (*DeductionFailure.getCallArgIndex() + 1)
      << *DeductionFailure.getFirstArg() << *DeductionFailure.getSecondArg()
      << TemplateArgString
      << (DeductionFailure.Result == Sema::TDK_DeducedMismatchNested);
  break;
}

case Sema::TDK_NonDeducedMismatch: {
  // FIXME: Provide a source location to indicate what we couldn't match.
  TemplateArgument FirstTA = *DeductionFailure.getFirstArg();
  TemplateArgument SecondTA = *DeductionFailure.getSecondArg();
  if (FirstTA.getKind() == TemplateArgument::Template &&
      SecondTA.getKind() == TemplateArgument::Template) {
    TemplateName FirstTN = FirstTA.getAsTemplate();
    TemplateName SecondTN = SecondTA.getAsTemplate();
    if (FirstTN.getKind() == TemplateName::Template &&
        SecondTN.getKind() == TemplateName::Template) {
      if (FirstTN.getAsTemplateDecl()->getName() ==
          SecondTN.getAsTemplateDecl()->getName()) {
        // FIXME: This fixes a bad diagnostic where both templates are named
        // the same.  This particular case is a bit difficult since:
        // 1) It is passed as a string to the diagnostic printer.
        // 2) The diagnostic printer only attempts to find a better
        //    name for types, not decls.
        // Ideally, this should folded into the diagnostic printer.
        S.Diag(Templated->getLocation(),
               diag::note_ovl_candidate_non_deduced_mismatch_qualified)
            << FirstTN.getAsTemplateDecl() << SecondTN.getAsTemplateDecl();
        return;
      }
    }
  }

  if (TakingCandidateAddress && isa<FunctionDecl>(Templated) &&
      !checkAddressOfCandidateIsAvailable(S, cast<FunctionDecl>(Templated)))
    return;

  // FIXME: For generic lambda parameters, check if the function is a lambda
  // call operator, and if so, emit a prettier and more informative
  // diagnostic that mentions 'auto' and lambda in addition to
  // (or instead of?) the canonical template type parameters.
  S.Diag(Templated->getLocation(),
         diag::note_ovl_candidate_non_deduced_mismatch)
      << FirstTA << SecondTA;
  return;
}
// TODO: diagnose these individually, then kill off
// note_ovl_candidate_bad_deduction, which is uselessly vague.
case Sema::TDK_MiscellaneousDeductionFailure:
  S.Diag(Templated->getLocation(), diag::note_ovl_candidate_bad_deduction);
  MaybeEmitInheritedConstructorNote(S, Found);
  return;
case Sema::TDK_CUDATargetMismatch:
  S.Diag(Templated->getLocation(),
         diag::note_cuda_ovl_candidate_target_mismatch);
  return;
}
10990}

10992/// Diagnose a failed template-argument deduction, for function calls.
10993static void DiagnoseBadDeduction(Sema &S, OverloadCandidate *Cand,
                               unsigned NumArgs,
                               bool TakingCandidateAddress) {
unsigned TDK = Cand->DeductionFailure.Result;
if (TDK == Sema::TDK_TooFewArguments || TDK == Sema::TDK_TooManyArguments) {
  if (CheckArityMismatch(S, Cand, NumArgs))
    return;
}
DiagnoseBadDeduction(S, Cand->FoundDecl, Cand->Function, // pattern
                     Cand->DeductionFailure, NumArgs, TakingCandidateAddress);
11003}

11005/// CUDA: diagnose an invalid call across targets.
11006static void DiagnoseBadTarget(Sema &S, OverloadCandidate *Cand) {
FunctionDecl *Caller = cast<FunctionDecl>(S.CurContext);
FunctionDecl *Callee = Cand->Function;

Sema::CUDAFunctionTarget CallerTarget = S.IdentifyCUDATarget(Caller),
                         CalleeTarget = S.IdentifyCUDATarget(Callee);

std::string FnDesc;
std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
    ClassifyOverloadCandidate(S, Cand->FoundDecl, Callee,
                              Cand->getRewriteKind(), FnDesc);

S.Diag(Callee->getLocation(), diag::note_ovl_candidate_bad_target)
    << (unsigned)FnKindPair.first << (unsigned)ocs_non_template
    << FnDesc /* Ignored */
    << CalleeTarget << CallerTarget;

// This could be an implicit constructor for which we could not infer the
// target due to a collsion. Diagnose that case.
CXXMethodDecl *Meth = dyn_cast<CXXMethodDecl>(Callee);
if (Meth != nullptr && Meth->isImplicit()) {
  CXXRecordDecl *ParentClass = Meth->getParent();
  Sema::CXXSpecialMember CSM;

  switch (FnKindPair.first) {
  default:
    return;
  case oc_implicit_default_constructor:
    CSM = Sema::CXXDefaultConstructor;
    break;
  case oc_implicit_copy_constructor:
    CSM = Sema::CXXCopyConstructor;
    break;
  case oc_implicit_move_constructor:
    CSM = Sema::CXXMoveConstructor;
    break;
  case oc_implicit_copy_assignment:
    CSM = Sema::CXXCopyAssignment;
    break;
  case oc_implicit_move_assignment:
    CSM = Sema::CXXMoveAssignment;
    break;
  };

  bool ConstRHS = false;
  if (Meth->getNumParams()) {
    if (const ReferenceType *RT =
            Meth->getParamDecl(0)->getType()->getAs<ReferenceType>()) {
      ConstRHS = RT->getPointeeType().isConstQualified();
    }
  }

  S.inferCUDATargetForImplicitSpecialMember(ParentClass, CSM, Meth,
                                            /* ConstRHS */ ConstRHS,
                                            /* Diagnose */ true);
}
11062}

11064static void DiagnoseFailedEnableIfAttr(Sema &S, OverloadCandidate *Cand) {
FunctionDecl *Callee = Cand->Function;
EnableIfAttr *Attr = static_cast<EnableIfAttr*>(Cand->DeductionFailure.Data);

S.Diag(Callee->getLocation(),
       diag::note_ovl_candidate_disabled_by_function_cond_attr)
    << Attr->getCond()->getSourceRange() << Attr->getMessage();
11071}

11073static void DiagnoseFailedExplicitSpec(Sema &S, OverloadCandidate *Cand) {
ExplicitSpecifier ES = ExplicitSpecifier::getFromDecl(Cand->Function);
assert(ES.isExplicit() && "not an explicit candidate")((void)0);

unsigned Kind;
switch (Cand->Function->getDeclKind()) {
case Decl::Kind::CXXConstructor:
  Kind = 0;
  break;
case Decl::Kind::CXXConversion:
  Kind = 1;
  break;
case Decl::Kind::CXXDeductionGuide:
  Kind = Cand->Function->isImplicit() ? 0 : 2;
  break;
default:
  llvm_unreachable("invalid Decl")__builtin_unreachable();
}

// Note the location of the first (in-class) declaration; a redeclaration
// (particularly an out-of-class definition) will typically lack the
// 'explicit' specifier.
// FIXME: This is probably a good thing to do for all 'candidate' notes.
FunctionDecl *First = Cand->Function->getFirstDecl();
if (FunctionDecl *Pattern = First->getTemplateInstantiationPattern())
  First = Pattern->getFirstDecl();

S.Diag(First->getLocation(),
       diag::note_ovl_candidate_explicit)
    << Kind << (ES.getExpr() ? 1 : 0)
    << (ES.getExpr() ? ES.getExpr()->getSourceRange() : SourceRange());
11104}

11106/// Generates a 'note' diagnostic for an overload candidate.  We've
11107/// already generated a primary error at the call site.
11108///
11109/// It really does need to be a single diagnostic with its caret
11110/// pointed at the candidate declaration.  Yes, this creates some
11111/// major challenges of technical writing.  Yes, this makes pointing
11112/// out problems with specific arguments quite awkward.  It's still
11113/// better than generating twenty screens of text for every failed
11114/// overload.
11115///
11116/// It would be great to be able to express per-candidate problems
11117/// more richly for those diagnostic clients that cared, but we'd
11118/// still have to be just as careful with the default diagnostics.
11119/// \param CtorDestAS Addr space of object being constructed (for ctor
11120/// candidates only).
11121static void NoteFunctionCandidate(Sema &S, OverloadCandidate *Cand,
                                unsigned NumArgs,
                                bool TakingCandidateAddress,
                                LangAS CtorDestAS = LangAS::Default) {
FunctionDecl *Fn = Cand->Function;
if (shouldSkipNotingLambdaConversionDecl(Fn))
  return;

// Note deleted candidates, but only if they're viable.
if (Cand->Viable) {
  if (Fn->isDeleted()) {
    std::string FnDesc;
    std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
        ClassifyOverloadCandidate(S, Cand->FoundDecl, Fn,
                                  Cand->getRewriteKind(), FnDesc);

    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_deleted)
        << (unsigned)FnKindPair.first << (unsigned)FnKindPair.second << FnDesc
        << (Fn->isDeleted() ? (Fn->isDeletedAsWritten() ? 1 : 2) : 0);
    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
    return;
  }

  // We don't really have anything else to say about viable candidates.
  S.NoteOverloadCandidate(Cand->FoundDecl, Fn, Cand->getRewriteKind());
  return;
}

switch (Cand->FailureKind) {
case ovl_fail_too_many_arguments:
case ovl_fail_too_few_arguments:
  return DiagnoseArityMismatch(S, Cand, NumArgs);

case ovl_fail_bad_deduction:
  return DiagnoseBadDeduction(S, Cand, NumArgs,
                              TakingCandidateAddress);

case ovl_fail_illegal_constructor: {
  S.Diag(Fn->getLocation(), diag::note_ovl_candidate_illegal_constructor)
    << (Fn->getPrimaryTemplate() ? 1 : 0);
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

case ovl_fail_object_addrspace_mismatch: {
  Qualifiers QualsForPrinting;
  QualsForPrinting.setAddressSpace(CtorDestAS);
  S.Diag(Fn->getLocation(),
         diag::note_ovl_candidate_illegal_constructor_adrspace_mismatch)
      << QualsForPrinting;
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;
}

case ovl_fail_trivial_conversion:
case ovl_fail_bad_final_conversion:
case ovl_fail_final_conversion_not_exact:
  return S.NoteOverloadCandidate(Cand->FoundDecl, Fn, Cand->getRewriteKind());

case ovl_fail_bad_conversion: {
  unsigned I = (Cand->IgnoreObjectArgument ? 1 : 0);
  for (unsigned N = Cand->Conversions.size(); I != N; ++I)
    if (Cand->Conversions[I].isBad())
      return DiagnoseBadConversion(S, Cand, I, TakingCandidateAddress);

  // FIXME: this currently happens when we're called from SemaInit
  // when user-conversion overload fails.  Figure out how to handle
  // those conditions and diagnose them well.
  return S.NoteOverloadCandidate(Cand->FoundDecl, Fn, Cand->getRewriteKind());
}

case ovl_fail_bad_target:
  return DiagnoseBadTarget(S, Cand);

case ovl_fail_enable_if:
  return DiagnoseFailedEnableIfAttr(S, Cand);

case ovl_fail_explicit:
  return DiagnoseFailedExplicitSpec(S, Cand);

case ovl_fail_inhctor_slice:
  // It's generally not interesting to note copy/move constructors here.
  if (cast<CXXConstructorDecl>(Fn)->isCopyOrMoveConstructor())
    return;
  S.Diag(Fn->getLocation(),
         diag::note_ovl_candidate_inherited_constructor_slice)
    << (Fn->getPrimaryTemplate() ? 1 : 0)
    << Fn->getParamDecl(0)->getType()->isRValueReferenceType();
  MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
  return;

case ovl_fail_addr_not_available: {
  bool Available = checkAddressOfCandidateIsAvailable(S, Cand->Function);
  (void)Available;
  assert(!Available)((void)0);
  break;
}
case ovl_non_default_multiversion_function:
  // Do nothing, these should simply be ignored.
  break;

case ovl_fail_constraints_not_satisfied: {
  std::string FnDesc;
  std::pair<OverloadCandidateKind, OverloadCandidateSelect> FnKindPair =
      ClassifyOverloadCandidate(S, Cand->FoundDecl, Fn,
                                Cand->getRewriteKind(), FnDesc);

  S.Diag(Fn->getLocation(),
         diag::note_ovl_candidate_constraints_not_satisfied)
      << (unsigned)FnKindPair.first << (unsigned)ocs_non_template
      << FnDesc /* Ignored */;
  ConstraintSatisfaction Satisfaction;
  if (S.CheckFunctionConstraints(Fn, Satisfaction))
    break;
  S.DiagnoseUnsatisfiedConstraint(Satisfaction);
}
}
11238}

11240static void NoteSurrogateCandidate(Sema &S, OverloadCandidate *Cand) {
if (shouldSkipNotingLambdaConversionDecl(Cand->Surrogate))
  return;

// Desugar the type of the surrogate down to a function type,
// retaining as many typedefs as possible while still showing
// the function type (and, therefore, its parameter types).
QualType FnType = Cand->Surrogate->getConversionType();
bool isLValueReference = false;
bool isRValueReference = false;
bool isPointer = false;
if (const LValueReferenceType *FnTypeRef =
      FnType->getAs<LValueReferenceType>()) {
  FnType = FnTypeRef->getPointeeType();
  isLValueReference = true;
} else if (const RValueReferenceType *FnTypeRef =
             FnType->getAs<RValueReferenceType>()) {
  FnType = FnTypeRef->getPointeeType();
  isRValueReference = true;
}
if (const PointerType *FnTypePtr = FnType->getAs<PointerType>()) {
  FnType = FnTypePtr->getPointeeType();
  isPointer = true;
}
// Desugar down to a function type.
FnType = QualType(FnType->getAs<FunctionType>(), 0);
// Reconstruct the pointer/reference as appropriate.
if (isPointer) FnType = S.Context.getPointerType(FnType);
if (isRValueReference) FnType = S.Context.getRValueReferenceType(FnType);
if (isLValueReference) FnType = S.Context.getLValueReferenceType(FnType);

S.Diag(Cand->Surrogate->getLocation(), diag::note_ovl_surrogate_cand)
  << FnType;
11273}

11275static void NoteBuiltinOperatorCandidate(Sema &S, StringRef Opc,
                                       SourceLocation OpLoc,
                                       OverloadCandidate *Cand) {
assert(Cand->Conversions.size() <= 2 && "builtin operator is not binary")((void)0);
std::string TypeStr("operator");
TypeStr += Opc;
TypeStr += "(";
TypeStr += Cand->BuiltinParamTypes[0].getAsString();
if (Cand->Conversions.size() == 1) {
  TypeStr += ")";
  S.Diag(OpLoc, diag::note_ovl_builtin_candidate) << TypeStr;
} else {
  TypeStr += ", ";
  TypeStr += Cand->BuiltinParamTypes[1].getAsString();
  TypeStr += ")";
  S.Diag(OpLoc, diag::note_ovl_builtin_candidate) << TypeStr;
}
11292}

11294static void NoteAmbiguousUserConversions(Sema &S, SourceLocation OpLoc,
                                       OverloadCandidate *Cand) {
for (const ImplicitConversionSequence &ICS : Cand->Conversions) {
  if (ICS.isBad()) break; // all meaningless after first invalid
  if (!ICS.isAmbiguous()) continue;

  ICS.DiagnoseAmbiguousConversion(
      S, OpLoc, S.PDiag(diag::note_ambiguous_type_conversion));
}
11303}

11305static SourceLocation GetLocationForCandidate(const OverloadCandidate *Cand) {
if (Cand->Function)
  return Cand->Function->getLocation();
if (Cand->IsSurrogate)
  return Cand->Surrogate->getLocation();
return SourceLocation();
11311}

11313static unsigned RankDeductionFailure(const DeductionFailureInfo &DFI) {
switch ((Sema::TemplateDeductionResult)DFI.Result) {
case Sema::TDK_Success:
case Sema::TDK_NonDependentConversionFailure:
  llvm_unreachable("non-deduction failure while diagnosing bad deduction")__builtin_unreachable();

case Sema::TDK_Invalid:
case Sema::TDK_Incomplete:
case Sema::TDK_IncompletePack:
  return 1;

case Sema::TDK_Underqualified:
case Sema::TDK_Inconsistent:
  return 2;

case Sema::TDK_SubstitutionFailure:
case Sema::TDK_DeducedMismatch:
case Sema::TDK_ConstraintsNotSatisfied:
case Sema::TDK_DeducedMismatchNested:
case Sema::TDK_NonDeducedMismatch:
case Sema::TDK_MiscellaneousDeductionFailure:
case Sema::TDK_CUDATargetMismatch:
  return 3;

case Sema::TDK_InstantiationDepth:
  return 4;

case Sema::TDK_InvalidExplicitArguments:
  return 5;

case Sema::TDK_TooManyArguments:
case Sema::TDK_TooFewArguments:
  return 6;
}
llvm_unreachable("Unhandled deduction result")__builtin_unreachable();
11348}

11350namespace {
11351struct CompareOverloadCandidatesForDisplay {
Sema &S;
SourceLocation Loc;
size_t NumArgs;
OverloadCandidateSet::CandidateSetKind CSK;

CompareOverloadCandidatesForDisplay(
    Sema &S, SourceLocation Loc, size_t NArgs,
    OverloadCandidateSet::CandidateSetKind CSK)
    : S(S), NumArgs(NArgs), CSK(CSK) {}

OverloadFailureKind EffectiveFailureKind(const OverloadCandidate *C) const {
  // If there are too many or too few arguments, that's the high-order bit we
  // want to sort by, even if the immediate failure kind was something else.
  if (C->FailureKind == ovl_fail_too_many_arguments ||
      C->FailureKind == ovl_fail_too_few_arguments)
    return static_cast<OverloadFailureKind>(C->FailureKind);

  if (C->Function) {
    if (NumArgs > C->Function->getNumParams() && !C->Function->isVariadic())
      return ovl_fail_too_many_arguments;
    if (NumArgs < C->Function->getMinRequiredArguments())
      return ovl_fail_too_few_arguments;
  }

  return static_cast<OverloadFailureKind>(C->FailureKind);
}

bool operator()(const OverloadCandidate *L,
                const OverloadCandidate *R) {
  // Fast-path this check.
  if (L == R) return false;

  // Order first by viability.
  if (L->Viable) {
    if (!R->Viable) return true;

    // TODO: introduce a tri-valued comparison for overload
    // candidates.  Would be more worthwhile if we had a sort
    // that could exploit it.
    if (isBetterOverloadCandidate(S, *L, *R, SourceLocation(), CSK))
      return true;
    if (isBetterOverloadCandidate(S, *R, *L, SourceLocation(), CSK))
      return false;
  } else if (R->Viable)
    return false;

  assert(L->Viable == R->Viable)((void)0);

  // Criteria by which we can sort non-viable candidates:
  if (!L->Viable) {
    OverloadFailureKind LFailureKind = EffectiveFailureKind(L);
    OverloadFailureKind RFailureKind = EffectiveFailureKind(R);

    // 1. Arity mismatches come after other candidates.
    if (LFailureKind == ovl_fail_too_many_arguments ||
        LFailureKind == ovl_fail_too_few_arguments) {
      if (RFailureKind == ovl_fail_too_many_arguments ||
          RFailureKind == ovl_fail_too_few_arguments) {
        int LDist = std::abs((int)L->getNumParams() - (int)NumArgs);
        int RDist = std::abs((int)R->getNumParams() - (int)NumArgs);
        if (LDist == RDist) {
          if (LFailureKind == RFailureKind)
            // Sort non-surrogates before surrogates.
            return !L->IsSurrogate && R->IsSurrogate;
          // Sort candidates requiring fewer parameters than there were
          // arguments given after candidates requiring more parameters
          // than there were arguments given.
          return LFailureKind == ovl_fail_too_many_arguments;
        }
        return LDist < RDist;
      }
      return false;
    }
    if (RFailureKind == ovl_fail_too_many_arguments ||
        RFailureKind == ovl_fail_too_few_arguments)
      return true;

    // 2. Bad conversions come first and are ordered by the number
    // of bad conversions and quality of good conversions.
    if (LFailureKind == ovl_fail_bad_conversion) {
      if (RFailureKind != ovl_fail_bad_conversion)
        return true;

      // The conversion that can be fixed with a smaller number of changes,
      // comes first.
      unsigned numLFixes = L->Fix.NumConversionsFixed;
      unsigned numRFixes = R->Fix.NumConversionsFixed;
      numLFixes = (numLFixes == 0) ? UINT_MAX(2147483647 *2U +1U) : numLFixes;
      numRFixes = (numRFixes == 0) ? UINT_MAX(2147483647 *2U +1U) : numRFixes;
      if (numLFixes != numRFixes) {
        return numLFixes < numRFixes;
      }

      // If there's any ordering between the defined conversions...
      // FIXME: this might not be transitive.
      assert(L->Conversions.size() == R->Conversions.size())((void)0);

      int leftBetter = 0;
      unsigned I = (L->IgnoreObjectArgument || R->IgnoreObjectArgument);
      for (unsigned E = L->Conversions.size(); I != E; ++I) {
        switch (CompareImplicitConversionSequences(S, Loc,
                                                   L->Conversions[I],
                                                   R->Conversions[I])) {
        case ImplicitConversionSequence::Better:
          leftBetter++;
          break;

        case ImplicitConversionSequence::Worse:
          leftBetter--;
          break;

        case ImplicitConversionSequence::Indistinguishable:
          break;
        }
      }
      if (leftBetter > 0) return true;
      if (leftBetter < 0) return false;

    } else if (RFailureKind == ovl_fail_bad_conversion)
      return false;

    if (LFailureKind == ovl_fail_bad_deduction) {
      if (RFailureKind != ovl_fail_bad_deduction)
        return true;

      if (L->DeductionFailure.Result != R->DeductionFailure.Result)
        return RankDeductionFailure(L->DeductionFailure)
             < RankDeductionFailure(R->DeductionFailure);
    } else if (RFailureKind == ovl_fail_bad_deduction)
      return false;

    // TODO: others?
  }

  // Sort everything else by location.
  SourceLocation LLoc = GetLocationForCandidate(L);
  SourceLocation RLoc = GetLocationForCandidate(R);

  // Put candidates without locations (e.g. builtins) at the end.
  if (LLoc.isInvalid()) return false;
  if (RLoc.isInvalid()) return true;

  return S.SourceMgr.isBeforeInTranslationUnit(LLoc, RLoc);
}
11496};
11497}

11499/// CompleteNonViableCandidate - Normally, overload resolution only
11500/// computes up to the first bad conversion. Produces the FixIt set if
11501/// possible.
11502static void
11503CompleteNonViableCandidate(Sema &S, OverloadCandidate *Cand,
                         ArrayRef<Expr *> Args,
                         OverloadCandidateSet::CandidateSetKind CSK) {
assert(!Cand->Viable)((void)0);

// Don't do anything on failures other than bad conversion.
if (Cand->FailureKind != ovl_fail_bad_conversion)
  return;

// We only want the FixIts if all the arguments can be corrected.
bool Unfixable = false;
// Use a implicit copy initialization to check conversion fixes.
Cand->Fix.setConversionChecker(TryCopyInitialization);

// Attempt to fix the bad conversion.
unsigned ConvCount = Cand->Conversions.size();
for (unsigned ConvIdx = (Cand->IgnoreObjectArgument ? 1 : 0); /**/;
     ++ConvIdx) {
  assert(ConvIdx != ConvCount && "no bad conversion in candidate")((void)0);
  if (Cand->Conversions[ConvIdx].isInitialized() &&
      Cand->Conversions[ConvIdx].isBad()) {
    Unfixable = !Cand->TryToFixBadConversion(ConvIdx, S);
    break;
  }
}

// FIXME: this should probably be preserved from the overload
// operation somehow.
bool SuppressUserConversions = false;

unsigned ConvIdx = 0;
unsigned ArgIdx = 0;
ArrayRef<QualType> ParamTypes;
bool Reversed = Cand->isReversed();

if (Cand->IsSurrogate) {
  QualType ConvType
    = Cand->Surrogate->getConversionType().getNonReferenceType();
  if (const PointerType *ConvPtrType = ConvType->getAs<PointerType>())
    ConvType = ConvPtrType->getPointeeType();
  ParamTypes = ConvType->castAs<FunctionProtoType>()->getParamTypes();
  // Conversion 0 is 'this', which doesn't have a corresponding parameter.
  ConvIdx = 1;
} else if (Cand->Function) {
  ParamTypes =
      Cand->Function->getType()->castAs<FunctionProtoType>()->getParamTypes();
  if (isa<CXXMethodDecl>(Cand->Function) &&
      !isa<CXXConstructorDecl>(Cand->Function) && !Reversed) {
    // Conversion 0 is 'this', which doesn't have a corresponding parameter.
    ConvIdx = 1;
    if (CSK == OverloadCandidateSet::CSK_Operator &&
        Cand->Function->getDeclName().getCXXOverloadedOperator() != OO_Call)
      // Argument 0 is 'this', which doesn't have a corresponding parameter.
      ArgIdx = 1;
  }
} else {
  // Builtin operator.
  assert(ConvCount <= 3)((void)0);
  ParamTypes = Cand->BuiltinParamTypes;
}

// Fill in the rest of the conversions.
for (unsigned ParamIdx = Reversed ? ParamTypes.size() - 1 : 0;
     ConvIdx != ConvCount;
     ++ConvIdx, ++ArgIdx, ParamIdx += (Reversed ? -1 : 1)) {
  assert(ArgIdx < Args.size() && "no argument for this arg conversion")((void)0);
  if (Cand->Conversions[ConvIdx].isInitialized()) {
    // We've already checked this conversion.
  } else if (ParamIdx < ParamTypes.size()) {
    if (ParamTypes[ParamIdx]->isDependentType())
      Cand->Conversions[ConvIdx].setAsIdentityConversion(
          Args[ArgIdx]->getType());
    else {
      Cand->Conversions[ConvIdx] =
          TryCopyInitialization(S, Args[ArgIdx], ParamTypes[ParamIdx],
                                SuppressUserConversions,
                                /*InOverloadResolution=*/true,
                                /*AllowObjCWritebackConversion=*/
                                S.getLangOpts().ObjCAutoRefCount);
      // Store the FixIt in the candidate if it exists.
      if (!Unfixable && Cand->Conversions[ConvIdx].isBad())
        Unfixable = !Cand->TryToFixBadConversion(ConvIdx, S);
    }
  } else
    Cand->Conversions[ConvIdx].setEllipsis();
}
11589}

11591SmallVector<OverloadCandidate *, 32> OverloadCandidateSet::CompleteCandidates(
  Sema &S, OverloadCandidateDisplayKind OCD, ArrayRef<Expr *> Args,
  SourceLocation OpLoc,
  llvm::function_ref<bool(OverloadCandidate &)> Filter) {
// Sort the candidates by viability and position.  Sorting directly would
// be prohibitive, so we make a set of pointers and sort those.
SmallVector<OverloadCandidate*, 32> Cands;
if (OCD == OCD_AllCandidates) Cands.reserve(size());
for (iterator Cand = begin(), LastCand = end(); Cand != LastCand; ++Cand) {
  if (!Filter(*Cand))
    continue;
  switch (OCD) {
  case OCD_AllCandidates:
    if (!Cand->Viable) {
      if (!Cand->Function && !Cand->IsSurrogate) {
        // This a non-viable builtin candidate.  We do not, in general,
        // want to list every possible builtin candidate.
        continue;
      }
      CompleteNonViableCandidate(S, Cand, Args, Kind);
    }
    break;

  case OCD_ViableCandidates:
    if (!Cand->Viable)
      continue;
    break;

  case OCD_AmbiguousCandidates:
    if (!Cand->Best)
      continue;
    break;
  }

  Cands.push_back(Cand);
}

llvm::stable_sort(
    Cands, CompareOverloadCandidatesForDisplay(S, OpLoc, Args.size(), Kind));

return Cands;
11632}

11634bool OverloadCandidateSet::shouldDeferDiags(Sema &S, ArrayRef<Expr *> Args,
                                          SourceLocation OpLoc) {
bool DeferHint = false;
if (S.getLangOpts().CUDA && S.getLangOpts().GPUDeferDiag) {
  // Defer diagnostic for CUDA/HIP if there are wrong-sided candidates or
  // host device candidates.
  auto WrongSidedCands =
      CompleteCandidates(S, OCD_AllCandidates, Args, OpLoc, [](auto &Cand) {
        return (Cand.Viable == false &&
                Cand.FailureKind == ovl_fail_bad_target) ||
               (Cand.Function &&
                Cand.Function->template hasAttr<CUDAHostAttr>() &&
                Cand.Function->template hasAttr<CUDADeviceAttr>());
      });
  DeferHint = !WrongSidedCands.empty();
}
return DeferHint;
11651}

11653/// When overload resolution fails, prints diagnostic messages containing the
11654/// candidates in the candidate set.
11655void OverloadCandidateSet::NoteCandidates(
  PartialDiagnosticAt PD, Sema &S, OverloadCandidateDisplayKind OCD,
  ArrayRef<Expr *> Args, StringRef Opc, SourceLocation OpLoc,
  llvm::function_ref<bool(OverloadCandidate &)> Filter) {

auto Cands = CompleteCandidates(S, OCD, Args, OpLoc, Filter);

S.Diag(PD.first, PD.second, shouldDeferDiags(S, Args, OpLoc));

NoteCandidates(S, Args, Cands, Opc, OpLoc);

if (OCD == OCD_AmbiguousCandidates)
  MaybeDiagnoseAmbiguousConstraints(S, {begin(), end()});
11668}

11670void OverloadCandidateSet::NoteCandidates(Sema &S, ArrayRef<Expr *> Args,
                                        ArrayRef<OverloadCandidate *> Cands,
                                        StringRef Opc, SourceLocation OpLoc) {
bool ReportedAmbiguousConversions = false;

const OverloadsShown ShowOverloads = S.Diags.getShowOverloads();
unsigned CandsShown = 0;
auto I = Cands.begin(), E = Cands.end();
for (; I != E; ++I) {
  OverloadCandidate *Cand = *I;

  if (CandsShown >= S.Diags.getNumOverloadCandidatesToShow() &&
      ShowOverloads == Ovl_Best) {
    break;
  }
  ++CandsShown;

  if (Cand->Function)
    NoteFunctionCandidate(S, Cand, Args.size(),
                          /*TakingCandidateAddress=*/false, DestAS);
  else if (Cand->IsSurrogate)
    NoteSurrogateCandidate(S, Cand);
  else {
    assert(Cand->Viable &&((void)0)
           "Non-viable built-in candidates are not added to Cands.")((void)0);
    // Generally we only see ambiguities including viable builtin
    // operators if overload resolution got screwed up by an
    // ambiguous user-defined conversion.
    //
    // FIXME: It's quite possible for different conversions to see
    // different ambiguities, though.
    if (!ReportedAmbiguousConversions) {
      NoteAmbiguousUserConversions(S, OpLoc, Cand);
      ReportedAmbiguousConversions = true;
    }

    // If this is a viable builtin, print it.
    NoteBuiltinOperatorCandidate(S, Opc, OpLoc, Cand);
  }
}

// Inform S.Diags that we've shown an overload set with N elements.  This may
// inform the future value of S.Diags.getNumOverloadCandidatesToShow().
S.Diags.overloadCandidatesShown(CandsShown);

if (I != E)
  S.Diag(OpLoc, diag::note_ovl_too_many_candidates,
         shouldDeferDiags(S, Args, OpLoc))
      << int(E - I);
11719}

11721static SourceLocation
11722GetLocationForCandidate(const TemplateSpecCandidate *Cand) {
return Cand->Specialization ? Cand->Specialization->getLocation()
                            : SourceLocation();
11725}

11727namespace {
11728struct CompareTemplateSpecCandidatesForDisplay {
Sema &S;
CompareTemplateSpecCandidatesForDisplay(Sema &S) : S(S) {}

bool operator()(const TemplateSpecCandidate *L,
                const TemplateSpecCandidate *R) {
  // Fast-path this check.
  if (L == R)
    return false;

  // Assuming that both candidates are not matches...

  // Sort by the ranking of deduction failures.
  if (L->DeductionFailure.Result != R->DeductionFailure.Result)
    return RankDeductionFailure(L->DeductionFailure) <
           RankDeductionFailure(R->DeductionFailure);

  // Sort everything else by location.
  SourceLocation LLoc = GetLocationForCandidate(L);
  SourceLocation RLoc = GetLocationForCandidate(R);

  // Put candidates without locations (e.g. builtins) at the end.
  if (LLoc.isInvalid())
    return false;
  if (RLoc.isInvalid())
    return true;

  return S.SourceMgr.isBeforeInTranslationUnit(LLoc, RLoc);
}
11757};
11758}

11760/// Diagnose a template argument deduction failure.
11761/// We are treating these failures as overload failures due to bad
11762/// deductions.
11763void TemplateSpecCandidate::NoteDeductionFailure(Sema &S,
                                               bool ForTakingAddress) {
DiagnoseBadDeduction(S, FoundDecl, Specialization, // pattern
                     DeductionFailure, /*NumArgs=*/0, ForTakingAddress);
11767}

11769void TemplateSpecCandidateSet::destroyCandidates() {
for (iterator i = begin(), e = end(); i != e; ++i) {
  i->DeductionFailure.Destroy();
}
11773}

11775void TemplateSpecCandidateSet::clear() {
destroyCandidates();
Candidates.clear();
11778}

11780/// NoteCandidates - When no template specialization match is found, prints
11781/// diagnostic messages containing the non-matching specializations that form
11782/// the candidate set.
11783/// This is analoguous to OverloadCandidateSet::NoteCandidates() with
11784/// OCD == OCD_AllCandidates and Cand->Viable == false.
11785void TemplateSpecCandidateSet::NoteCandidates(Sema &S, SourceLocation Loc) {
// Sort the candidates by position (assuming no candidate is a match).
// Sorting directly would be prohibitive, so we make a set of pointers
// and sort those.
SmallVector<TemplateSpecCandidate *, 32> Cands;
Cands.reserve(size());
for (iterator Cand = begin(), LastCand = end(); Cand != LastCand; ++Cand) {
  if (Cand->Specialization)
    Cands.push_back(Cand);
  // Otherwise, this is a non-matching builtin candidate.  We do not,
  // in general, want to list every possible builtin candidate.
}

llvm::sort(Cands, CompareTemplateSpecCandidatesForDisplay(S));

// FIXME: Perhaps rename OverloadsShown and getShowOverloads()
// for generalization purposes (?).
const OverloadsShown ShowOverloads = S.Diags.getShowOverloads();

SmallVectorImpl<TemplateSpecCandidate *>::iterator I, E;
unsigned CandsShown = 0;
for (I = Cands.begin(), E = Cands.end(); I != E; ++I) {
  TemplateSpecCandidate *Cand = *I;

  // Set an arbitrary limit on the number of candidates we'll spam
  // the user with.  FIXME: This limit should depend on details of the
  // candidate list.
  if (CandsShown >= 4 && ShowOverloads == Ovl_Best)
    break;
  ++CandsShown;

  assert(Cand->Specialization &&((void)0)
         "Non-matching built-in candidates are not added to Cands.")((void)0);
  Cand->NoteDeductionFailure(S, ForTakingAddress);
}

if (I != E)
  S.Diag(Loc, diag::note_ovl_too_many_candidates) << int(E - I);
11823}

11825// [PossiblyAFunctionType]  -->   [Return]
11826// NonFunctionType --> NonFunctionType
11827// R (A) --> R(A)
11828// R (*)(A) --> R (A)
11829// R (&)(A) --> R (A)
11830// R (S::*)(A) --> R (A)
11831QualType Sema::ExtractUnqualifiedFunctionType(QualType PossiblyAFunctionType) {
QualType Ret = PossiblyAFunctionType;
if (const PointerType *ToTypePtr =
  PossiblyAFunctionType->getAs<PointerType>())
  Ret = ToTypePtr->getPointeeType();
else if (const ReferenceType *ToTypeRef =
  PossiblyAFunctionType->getAs<ReferenceType>())
  Ret = ToTypeRef->getPointeeType();
else if (const MemberPointerType *MemTypePtr =
  PossiblyAFunctionType->getAs<MemberPointerType>())
  Ret = MemTypePtr->getPointeeType();
Ret =
  Context.getCanonicalType(Ret).getUnqualifiedType();
return Ret;
11845}

11847static bool completeFunctionType(Sema &S, FunctionDecl *FD, SourceLocation Loc,
                               bool Complain = true) {
if (S.getLangOpts().CPlusPlus14 && FD->getReturnType()->isUndeducedType() &&
    S.DeduceReturnType(FD, Loc, Complain))
  return true;

auto *FPT = FD->getType()->castAs<FunctionProtoType>();
if (S.getLangOpts().CPlusPlus17 &&
    isUnresolvedExceptionSpec(FPT->getExceptionSpecType()) &&
    !S.ResolveExceptionSpec(Loc, FPT))
  return true;

return false;
11860}

11862namespace {
11863// A helper class to help with address of function resolution
11864// - allows us to avoid passing around all those ugly parameters
11865class AddressOfFunctionResolver {
Sema& S;
Expr* SourceExpr;
const QualType& TargetType;
QualType TargetFunctionType; // Extracted function type from target type

bool Complain;
//DeclAccessPair& ResultFunctionAccessPair;
ASTContext& Context;

bool TargetTypeIsNonStaticMemberFunction;
bool FoundNonTemplateFunction;
bool StaticMemberFunctionFromBoundPointer;
bool HasComplained;

OverloadExpr::FindResult OvlExprInfo;
OverloadExpr *OvlExpr;
TemplateArgumentListInfo OvlExplicitTemplateArgs;
SmallVector<std::pair<DeclAccessPair, FunctionDecl*>, 4> Matches;
TemplateSpecCandidateSet FailedCandidates;

11886public:
AddressOfFunctionResolver(Sema &S, Expr *SourceExpr,
                          const QualType &TargetType, bool Complain)
    : S(S), SourceExpr(SourceExpr), TargetType(TargetType),
      Complain(Complain), Context(S.getASTContext()),
      TargetTypeIsNonStaticMemberFunction(
          !!TargetType->getAs<MemberPointerType>()),
      FoundNonTemplateFunction(false),
      StaticMemberFunctionFromBoundPointer(false),
      HasComplained(false),
      OvlExprInfo(OverloadExpr::find(SourceExpr)),
      OvlExpr(OvlExprInfo.Expression),
      FailedCandidates(OvlExpr->getNameLoc(), /*ForTakingAddress=*/true) {
  ExtractUnqualifiedFunctionTypeFromTargetType();

  if (TargetFunctionType->isFunctionType()) {
    if (UnresolvedMemberExpr *UME = dyn_cast<UnresolvedMemberExpr>(OvlExpr))
      if (!UME->isImplicitAccess() &&
          !S.ResolveSingleFunctionTemplateSpecialization(UME))
        StaticMemberFunctionFromBoundPointer = true;
  } else if (OvlExpr->hasExplicitTemplateArgs()) {
    DeclAccessPair dap;
    if (FunctionDecl *Fn = S.ResolveSingleFunctionTemplateSpecialization(
            OvlExpr, false, &dap)) {
      if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
        if (!Method->isStatic()) {
          // If the target type is a non-function type and the function found
          // is a non-static member function, pretend as if that was the
          // target, it's the only possible type to end up with.
          TargetTypeIsNonStaticMemberFunction = true;

          // And skip adding the function if its not in the proper form.
          // We'll diagnose this due to an empty set of functions.
          if (!OvlExprInfo.HasFormOfMemberPointer)
            return;
        }

      Matches.push_back(std::make_pair(dap, Fn));
    }
    return;
  }

  if (OvlExpr->hasExplicitTemplateArgs())
    OvlExpr->copyTemplateArgumentsInto(OvlExplicitTemplateArgs);

  if (FindAllFunctionsThatMatchTargetTypeExactly()) {
    // C++ [over.over]p4:
    //   If more than one function is selected, [...]
    if (Matches.size() > 1 && !eliminiateSuboptimalOverloadCandidates()) {
      if (FoundNonTemplateFunction)
        EliminateAllTemplateMatches();
      else
        EliminateAllExceptMostSpecializedTemplate();
    }
  }

  if (S.getLangOpts().CUDA && Matches.size() > 1)
    EliminateSuboptimalCudaMatches();
}

bool hasComplained() const { return HasComplained; }

11948private:
bool candidateHasExactlyCorrectType(const FunctionDecl *FD) {
  QualType Discard;
  return Context.hasSameUnqualifiedType(TargetFunctionType, FD->getType()) ||
         S.IsFunctionConversion(FD->getType(), TargetFunctionType, Discard);
}

/// \return true if A is considered a better overload candidate for the
/// desired type than B.
bool isBetterCandidate(const FunctionDecl *A, const FunctionDecl *B) {
  // If A doesn't have exactly the correct type, we don't want to classify it
  // as "better" than anything else. This way, the user is required to
  // disambiguate for us if there are multiple candidates and no exact match.
  return candidateHasExactlyCorrectType(A) &&
         (!candidateHasExactlyCorrectType(B) ||
          compareEnableIfAttrs(S, A, B) == Comparison::Better);
}

/// \return true if we were able to eliminate all but one overload candidate,
/// false otherwise.
bool eliminiateSuboptimalOverloadCandidates() {
  // Same algorithm as overload resolution -- one pass to pick the "best",
  // another pass to be sure that nothing is better than the best.
  auto Best = Matches.begin();
  for (auto I = Matches.begin()+1, E = Matches.end(); I != E; ++I)
    if (isBetterCandidate(I->second, Best->second))
      Best = I;

  const FunctionDecl *BestFn = Best->second;
  auto IsBestOrInferiorToBest = [this, BestFn](
      const std::pair<DeclAccessPair, FunctionDecl *> &Pair) {
    return BestFn == Pair.second || isBetterCandidate(BestFn, Pair.second);
  };

  // Note: We explicitly leave Matches unmodified if there isn't a clear best
  // option, so we can potentially give the user a better error
  if (!llvm::all_of(Matches, IsBestOrInferiorToBest))
    return false;
  Matches[0] = *Best;
  Matches.resize(1);
  return true;
}

bool isTargetTypeAFunction() const {
  return TargetFunctionType->isFunctionType();
}

// [ToType]     [Return]

// R (*)(A) --> R (A), IsNonStaticMemberFunction = false
// R (&)(A) --> R (A), IsNonStaticMemberFunction = false
// R (S::*)(A) --> R (A), IsNonStaticMemberFunction = true
void inline ExtractUnqualifiedFunctionTypeFromTargetType() {
  TargetFunctionType = S.ExtractUnqualifiedFunctionType(TargetType);
}

// return true if any matching specializations were found
bool AddMatchingTemplateFunction(FunctionTemplateDecl* FunctionTemplate,
                                 const DeclAccessPair& CurAccessFunPair) {
  if (CXXMethodDecl *Method
            = dyn_cast<CXXMethodDecl>(FunctionTemplate->getTemplatedDecl())) {
    // Skip non-static function templates when converting to pointer, and
    // static when converting to member pointer.
    if (Method->isStatic() == TargetTypeIsNonStaticMemberFunction)
      return false;
  }
  else if (TargetTypeIsNonStaticMemberFunction)
    return false;

  // C++ [over.over]p2:
  //   If the name is a function template, template argument deduction is
  //   done (14.8.2.2), and if the argument deduction succeeds, the
  //   resulting template argument list is used to generate a single
  //   function template specialization, which is added to the set of
  //   overloaded functions considered.
  FunctionDecl *Specialization = nullptr;
  TemplateDeductionInfo Info(FailedCandidates.getLocation());
  if (Sema::TemplateDeductionResult Result
        = S.DeduceTemplateArguments(FunctionTemplate,
                                    &OvlExplicitTemplateArgs,
                                    TargetFunctionType, Specialization,
                                    Info, /*IsAddressOfFunction*/true)) {
    // Make a note of the failed deduction for diagnostics.
    FailedCandidates.addCandidate()
        .set(CurAccessFunPair, FunctionTemplate->getTemplatedDecl(),
             MakeDeductionFailureInfo(Context, Result, Info));
    return false;
  }

  // Template argument deduction ensures that we have an exact match or
  // compatible pointer-to-function arguments that would be adjusted by ICS.
  // This function template specicalization works.
  assert(S.isSameOrCompatibleFunctionType(((void)0)
            Context.getCanonicalType(Specialization->getType()),((void)0)
            Context.getCanonicalType(TargetFunctionType)))((void)0);

  if (!S.checkAddressOfFunctionIsAvailable(Specialization))
    return false;

  Matches.push_back(std::make_pair(CurAccessFunPair, Specialization));
  return true;
}

bool AddMatchingNonTemplateFunction(NamedDecl* Fn,
                                    const DeclAccessPair& CurAccessFunPair) {
  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn)) {
    // Skip non-static functions when converting to pointer, and static
    // when converting to member pointer.
    if (Method->isStatic() == TargetTypeIsNonStaticMemberFunction)
      return false;
  }
  else if (TargetTypeIsNonStaticMemberFunction)
    return false;

  if (FunctionDecl *FunDecl = dyn_cast<FunctionDecl>(Fn)) {
    if (S.getLangOpts().CUDA)
      if (FunctionDecl *Caller = dyn_cast<FunctionDecl>(S.CurContext))
        if (!Caller->isImplicit() && !S.IsAllowedCUDACall(Caller, FunDecl))
          return false;
    if (FunDecl->isMultiVersion()) {
      const auto *TA = FunDecl->getAttr<TargetAttr>();
      if (TA && !TA->isDefaultVersion())
        return false;
    }

    // If any candidate has a placeholder return type, trigger its deduction
    // now.
    if (completeFunctionType(S, FunDecl, SourceExpr->getBeginLoc(),
                             Complain)) {
      HasComplained |= Complain;
      return false;
    }

    if (!S.checkAddressOfFunctionIsAvailable(FunDecl))
      return false;

    // If we're in C, we need to support types that aren't exactly identical.
    if (!S.getLangOpts().CPlusPlus ||
        candidateHasExactlyCorrectType(FunDecl)) {
      Matches.push_back(std::make_pair(
          CurAccessFunPair, cast<FunctionDecl>(FunDecl->getCanonicalDecl())));
      FoundNonTemplateFunction = true;
      return true;
    }
  }

  return false;
}

bool FindAllFunctionsThatMatchTargetTypeExactly() {
  bool Ret = false;

  // If the overload expression doesn't have the form of a pointer to
  // member, don't try to convert it to a pointer-to-member type.
  if (IsInvalidFormOfPointerToMemberFunction())
    return false;

  for (UnresolvedSetIterator I = OvlExpr->decls_begin(),
                             E = OvlExpr->decls_end();
       I != E; ++I) {
    // Look through any using declarations to find the underlying function.
    NamedDecl *Fn = (*I)->getUnderlyingDecl();

    // C++ [over.over]p3:
    //   Non-member functions and static member functions match
    //   targets of type "pointer-to-function" or "reference-to-function."
    //   Nonstatic member functions match targets of
    //   type "pointer-to-member-function."
    // Note that according to DR 247, the containing class does not matter.
    if (FunctionTemplateDecl *FunctionTemplate
                                      = dyn_cast<FunctionTemplateDecl>(Fn)) {
      if (AddMatchingTemplateFunction(FunctionTemplate, I.getPair()))
        Ret = true;
    }
    // If we have explicit template arguments supplied, skip non-templates.
    else if (!OvlExpr->hasExplicitTemplateArgs() &&
             AddMatchingNonTemplateFunction(Fn, I.getPair()))
      Ret = true;
  }
  assert(Ret || Matches.empty())((void)0);
  return Ret;
}

void EliminateAllExceptMostSpecializedTemplate() {
  //   [...] and any given function template specialization F1 is
  //   eliminated if the set contains a second function template
  //   specialization whose function template is more specialized
  //   than the function template of F1 according to the partial
  //   ordering rules of 14.5.5.2.

  // The algorithm specified above is quadratic. We instead use a
  // two-pass algorithm (similar to the one used to identify the
  // best viable function in an overload set) that identifies the
  // best function template (if it exists).

  UnresolvedSet<4> MatchesCopy; // TODO: avoid!
  for (unsigned I = 0, E = Matches.size(); I != E; ++I)
    MatchesCopy.addDecl(Matches[I].second, Matches[I].first.getAccess());

  // TODO: It looks like FailedCandidates does not serve much purpose
  // here, since the no_viable diagnostic has index 0.
  UnresolvedSetIterator Result = S.getMostSpecialized(
      MatchesCopy.begin(), MatchesCopy.end(), FailedCandidates,
      SourceExpr->getBeginLoc(), S.PDiag(),
      S.PDiag(diag::err_addr_ovl_ambiguous)
          << Matches[0].second->getDeclName(),
      S.PDiag(diag::note_ovl_candidate)
          << (unsigned)oc_function << (unsigned)ocs_described_template,
      Complain, TargetFunctionType);

  if (Result != MatchesCopy.end()) {
    // Make it the first and only element
    Matches[0].first = Matches[Result - MatchesCopy.begin()].first;
    Matches[0].second = cast<FunctionDecl>(*Result);
    Matches.resize(1);
  } else
    HasComplained |= Complain;
}

void EliminateAllTemplateMatches() {
  //   [...] any function template specializations in the set are
  //   eliminated if the set also contains a non-template function, [...]
  for (unsigned I = 0, N = Matches.size(); I != N; ) {
    if (Matches[I].second->getPrimaryTemplate() == nullptr)
      ++I;
    else {
      Matches[I] = Matches[--N];
      Matches.resize(N);
    }
  }
}

void EliminateSuboptimalCudaMatches() {
  S.EraseUnwantedCUDAMatches(dyn_cast<FunctionDecl>(S.CurContext), Matches);
}

12184public:
void ComplainNoMatchesFound() const {
  assert(Matches.empty())((void)0);
  S.Diag(OvlExpr->getBeginLoc(), diag::err_addr_ovl_no_viable)
      << OvlExpr->getName() << TargetFunctionType
      << OvlExpr->getSourceRange();
  if (FailedCandidates.empty())
    S.NoteAllOverloadCandidates(OvlExpr, TargetFunctionType,
                                /*TakingAddress=*/true);
  else {
    // We have some deduction failure messages. Use them to diagnose
    // the function templates, and diagnose the non-template candidates
    // normally.
    for (UnresolvedSetIterator I = OvlExpr->decls_begin(),
                               IEnd = OvlExpr->decls_end();
         I != IEnd; ++I)
      if (FunctionDecl *Fun =
              dyn_cast<FunctionDecl>((*I)->getUnderlyingDecl()))
        if (!functionHasPassObjectSizeParams(Fun))
          S.NoteOverloadCandidate(*I, Fun, CRK_None, TargetFunctionType,
                                  /*TakingAddress=*/true);
    FailedCandidates.NoteCandidates(S, OvlExpr->getBeginLoc());
  }
}

bool IsInvalidFormOfPointerToMemberFunction() const {
  return TargetTypeIsNonStaticMemberFunction &&
    !OvlExprInfo.HasFormOfMemberPointer;
}

void ComplainIsInvalidFormOfPointerToMemberFunction() const {
    // TODO: Should we condition this on whether any functions might
    // have matched, or is it more appropriate to do that in callers?
    // TODO: a fixit wouldn't hurt.
    S.Diag(OvlExpr->getNameLoc(), diag::err_addr_ovl_no_qualifier)
      << TargetType << OvlExpr->getSourceRange();
}

bool IsStaticMemberFunctionFromBoundPointer() const {
  return StaticMemberFunctionFromBoundPointer;
}

void ComplainIsStaticMemberFunctionFromBoundPointer() const {
  S.Diag(OvlExpr->getBeginLoc(),
         diag::err_invalid_form_pointer_member_function)
      << OvlExpr->getSourceRange();
}

void ComplainOfInvalidConversion() const {
  S.Diag(OvlExpr->getBeginLoc(), diag::err_addr_ovl_not_func_ptrref)
      << OvlExpr->getName() << TargetType;
}

void ComplainMultipleMatchesFound() const {
  assert(Matches.size() > 1)((void)0);
  S.Diag(OvlExpr->getBeginLoc(), diag::err_addr_ovl_ambiguous)
      << OvlExpr->getName() << OvlExpr->getSourceRange();
  S.NoteAllOverloadCandidates(OvlExpr, TargetFunctionType,
                              /*TakingAddress=*/true);
}

bool hadMultipleCandidates() const { return (OvlExpr->getNumDecls() > 1); }

int getNumMatches() const { return Matches.size(); }

FunctionDecl* getMatchingFunctionDecl() const {
  if (Matches.size() != 1) return nullptr;
  return Matches[0].second;
}

const DeclAccessPair* getMatchingFunctionAccessPair() const {
  if (Matches.size() != 1) return nullptr;
  return &Matches[0].first;
}
12258};
12259}

12261/// ResolveAddressOfOverloadedFunction - Try to resolve the address of
12262/// an overloaded function (C++ [over.over]), where @p From is an
12263/// expression with overloaded function type and @p ToType is the type
12264/// we're trying to resolve to. For example:
12265///
12266/// @code
12267/// int f(double);
12268/// int f(int);
12269///
12270/// int (*pfd)(double) = f; // selects f(double)
12271/// @endcode
12272///
12273/// This routine returns the resulting FunctionDecl if it could be
12274/// resolved, and NULL otherwise. When @p Complain is true, this
12275/// routine will emit diagnostics if there is an error.
12276FunctionDecl *
12277Sema::ResolveAddressOfOverloadedFunction(Expr *AddressOfExpr,
                                       QualType TargetType,
                                       bool Complain,
                                       DeclAccessPair &FoundResult,
                                       bool *pHadMultipleCandidates) {
assert(AddressOfExpr->getType() == Context.OverloadTy)((void)0);

AddressOfFunctionResolver Resolver(*this, AddressOfExpr, TargetType,
                                   Complain);
int NumMatches = Resolver.getNumMatches();
FunctionDecl *Fn = nullptr;
bool ShouldComplain = Complain && !Resolver.hasComplained();
if (NumMatches == 0 && ShouldComplain) {
  if (Resolver.IsInvalidFormOfPointerToMemberFunction())
    Resolver.ComplainIsInvalidFormOfPointerToMemberFunction();
  else
    Resolver.ComplainNoMatchesFound();
}
else if (NumMatches > 1 && ShouldComplain)
  Resolver.ComplainMultipleMatchesFound();
else if (NumMatches == 1) {
  Fn = Resolver.getMatchingFunctionDecl();
  assert(Fn)((void)0);
  if (auto *FPT = Fn->getType()->getAs<FunctionProtoType>())
    ResolveExceptionSpec(AddressOfExpr->getExprLoc(), FPT);
  FoundResult = *Resolver.getMatchingFunctionAccessPair();
  if (Complain) {
    if (Resolver.IsStaticMemberFunctionFromBoundPointer())
      Resolver.ComplainIsStaticMemberFunctionFromBoundPointer();
    else
      CheckAddressOfMemberAccess(AddressOfExpr, FoundResult);
  }
}

if (pHadMultipleCandidates)
  *pHadMultipleCandidates = Resolver.hadMultipleCandidates();
return Fn;
12314}

12316/// Given an expression that refers to an overloaded function, try to
12317/// resolve that function to a single function that can have its address taken.
12318/// This will modify `Pair` iff it returns non-null.
12319///
12320/// This routine can only succeed if from all of the candidates in the overload
12321/// set for SrcExpr that can have their addresses taken, there is one candidate
12322/// that is more constrained than the rest.
12323FunctionDecl *
12324Sema::resolveAddressOfSingleOverloadCandidate(Expr *E, DeclAccessPair &Pair) {
OverloadExpr::FindResult R = OverloadExpr::find(E);
OverloadExpr *Ovl = R.Expression;
bool IsResultAmbiguous = false;
FunctionDecl *Result = nullptr;
DeclAccessPair DAP;
SmallVector<FunctionDecl *, 2> AmbiguousDecls;

auto CheckMoreConstrained =
    [&] (FunctionDecl *FD1, FunctionDecl *FD2) -> Optional<bool> {
      SmallVector<const Expr *, 1> AC1, AC2;
      FD1->getAssociatedConstraints(AC1);
      FD2->getAssociatedConstraints(AC2);
      bool AtLeastAsConstrained1, AtLeastAsConstrained2;
      if (IsAtLeastAsConstrained(FD1, AC1, FD2, AC2, AtLeastAsConstrained1))
        return None;
      if (IsAtLeastAsConstrained(FD2, AC2, FD1, AC1, AtLeastAsConstrained2))
        return None;
      if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
        return None;
      return AtLeastAsConstrained1;
    };

// Don't use the AddressOfResolver because we're specifically looking for
// cases where we have one overload candidate that lacks
// enable_if/pass_object_size/...
for (auto I = Ovl->decls_begin(), E = Ovl->decls_end(); I != E; ++I) {
  auto *FD = dyn_cast<FunctionDecl>(I->getUnderlyingDecl());
  if (!FD)
    return nullptr;

  if (!checkAddressOfFunctionIsAvailable(FD))
    continue;

  // We have more than one result - see if it is more constrained than the
  // previous one.
  if (Result) {
    Optional<bool> MoreConstrainedThanPrevious = CheckMoreConstrained(FD,
                                                                      Result);
    if (!MoreConstrainedThanPrevious) {
      IsResultAmbiguous = true;
      AmbiguousDecls.push_back(FD);
      continue;
    }
    if (!*MoreConstrainedThanPrevious)
      continue;
    // FD is more constrained - replace Result with it.
  }
  IsResultAmbiguous = false;
  DAP = I.getPair();
  Result = FD;
}

if (IsResultAmbiguous)
  return nullptr;

if (Result) {
  SmallVector<const Expr *, 1> ResultAC;
  // We skipped over some ambiguous declarations which might be ambiguous with
  // the selected result.
  for (FunctionDecl *Skipped : AmbiguousDecls)
    if (!CheckMoreConstrained(Skipped, Result).hasValue())
      return nullptr;
  Pair = DAP;
}
return Result;
12390}

12392/// Given an overloaded function, tries to turn it into a non-overloaded
12393/// function reference using resolveAddressOfSingleOverloadCandidate. This
12394/// will perform access checks, diagnose the use of the resultant decl, and, if
12395/// requested, potentially perform a function-to-pointer decay.
12396///
12397/// Returns false if resolveAddressOfSingleOverloadCandidate fails.
12398/// Otherwise, returns true. This may emit diagnostics and return true.
12399bool Sema::resolveAndFixAddressOfSingleOverloadCandidate(
  ExprResult &SrcExpr, bool DoFunctionPointerConverion) {
Expr *E = SrcExpr.get();
assert(E->getType() == Context.OverloadTy && "SrcExpr must be an overload")((void)0);

DeclAccessPair DAP;
FunctionDecl *Found = resolveAddressOfSingleOverloadCandidate(E, DAP);
if (!Found || Found->isCPUDispatchMultiVersion() ||
    Found->isCPUSpecificMultiVersion())
  return false;

// Emitting multiple diagnostics for a function that is both inaccessible and
// unavailable is consistent with our behavior elsewhere. So, always check
// for both.
DiagnoseUseOfDecl(Found, E->getExprLoc());
CheckAddressOfMemberAccess(E, DAP);
Expr *Fixed = FixOverloadedFunctionReference(E, DAP, Found);
if (DoFunctionPointerConverion && Fixed->getType()->isFunctionType())
  SrcExpr = DefaultFunctionArrayConversion(Fixed, /*Diagnose=*/false);
else
  SrcExpr = Fixed;
return true;
12421}

12423/// Given an expression that refers to an overloaded function, try to
12424/// resolve that overloaded function expression down to a single function.
12425///
12426/// This routine can only resolve template-ids that refer to a single function
12427/// template, where that template-id refers to a single template whose template
12428/// arguments are either provided by the template-id or have defaults,
12429/// as described in C++0x [temp.arg.explicit]p3.
12430///
12431/// If no template-ids are found, no diagnostics are emitted and NULL is
12432/// returned.
12433FunctionDecl *
12434Sema::ResolveSingleFunctionTemplateSpecialization(OverloadExpr *ovl,
                                                bool Complain,
                                                DeclAccessPair *FoundResult) {
// C++ [over.over]p1:
//   [...] [Note: any redundant set of parentheses surrounding the
//   overloaded function name is ignored (5.1). ]
// C++ [over.over]p1:
//   [...] The overloaded function name can be preceded by the &
//   operator.

// If we didn't actually find any template-ids, we're done.
if (!ovl->hasExplicitTemplateArgs())
  return nullptr;

TemplateArgumentListInfo ExplicitTemplateArgs;
ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
TemplateSpecCandidateSet FailedCandidates(ovl->getNameLoc());

// Look through all of the overloaded functions, searching for one
// whose type matches exactly.
FunctionDecl *Matched = nullptr;
for (UnresolvedSetIterator I = ovl->decls_begin(),
       E = ovl->decls_end(); I != E; ++I) {
  // C++0x [temp.arg.explicit]p3:
  //   [...] In contexts where deduction is done and fails, or in contexts
  //   where deduction is not done, if a template argument list is
  //   specified and it, along with any default template arguments,
  //   identifies a single function template specialization, then the
  //   template-id is an lvalue for the function template specialization.
  FunctionTemplateDecl *FunctionTemplate
    = cast<FunctionTemplateDecl>((*I)->getUnderlyingDecl());

  // C++ [over.over]p2:
  //   If the name is a function template, template argument deduction is
  //   done (14.8.2.2), and if the argument deduction succeeds, the
  //   resulting template argument list is used to generate a single
  //   function template specialization, which is added to the set of
  //   overloaded functions considered.
  FunctionDecl *Specialization = nullptr;
  TemplateDeductionInfo Info(FailedCandidates.getLocation());
  if (TemplateDeductionResult Result
        = DeduceTemplateArguments(FunctionTemplate, &ExplicitTemplateArgs,
                                  Specialization, Info,
                                  /*IsAddressOfFunction*/true)) {
    // Make a note of the failed deduction for diagnostics.
    // TODO: Actually use the failed-deduction info?
    FailedCandidates.addCandidate()
        .set(I.getPair(), FunctionTemplate->getTemplatedDecl(),
             MakeDeductionFailureInfo(Context, Result, Info));
    continue;
  }

  assert(Specialization && "no specialization and no error?")((void)0);

  // Multiple matches; we can't resolve to a single declaration.
  if (Matched) {
    if (Complain) {
      Diag(ovl->getExprLoc(), diag::err_addr_ovl_ambiguous)
        << ovl->getName();
      NoteAllOverloadCandidates(ovl);
    }
    return nullptr;
  }

  Matched = Specialization;
  if (FoundResult) *FoundResult = I.getPair();
}

if (Matched &&
    completeFunctionType(*this, Matched, ovl->getExprLoc(), Complain))
  return nullptr;

return Matched;
12507}

12509// Resolve and fix an overloaded expression that can be resolved
12510// because it identifies a single function template specialization.
12511//
12512// Last three arguments should only be supplied if Complain = true
12513//
12514// Return true if it was logically possible to so resolve the
12515// expression, regardless of whether or not it succeeded.  Always
12516// returns true if 'complain' is set.
12517bool Sema::ResolveAndFixSingleFunctionTemplateSpecialization(
                    ExprResult &SrcExpr, bool doFunctionPointerConverion,
                    bool complain, SourceRange OpRangeForComplaining,
                                         QualType DestTypeForComplaining,
                                          unsigned DiagIDForComplaining) {
assert(SrcExpr.get()->getType() == Context.OverloadTy)((void)0);

OverloadExpr::FindResult ovl = OverloadExpr::find(SrcExpr.get());

DeclAccessPair found;
ExprResult SingleFunctionExpression;
if (FunctionDecl *fn = ResolveSingleFunctionTemplateSpecialization(
                         ovl.Expression, /*complain*/ false, &found)) {
  if (DiagnoseUseOfDecl(fn, SrcExpr.get()->getBeginLoc())) {
    SrcExpr = ExprError();
    return true;
  }

  // It is only correct to resolve to an instance method if we're
  // resolving a form that's permitted to be a pointer to member.
  // Otherwise we'll end up making a bound member expression, which
  // is illegal in all the contexts we resolve like this.
  if (!ovl.HasFormOfMemberPointer &&
      isa<CXXMethodDecl>(fn) &&
      cast<CXXMethodDecl>(fn)->isInstance()) {
    if (!complain) return false;

    Diag(ovl.Expression->getExprLoc(),
         diag::err_bound_member_function)
      << 0 << ovl.Expression->getSourceRange();

    // TODO: I believe we only end up here if there's a mix of
    // static and non-static candidates (otherwise the expression
    // would have 'bound member' type, not 'overload' type).
    // Ideally we would note which candidate was chosen and why
    // the static candidates were rejected.
    SrcExpr = ExprError();
    return true;
  }

  // Fix the expression to refer to 'fn'.
  SingleFunctionExpression =
      FixOverloadedFunctionReference(SrcExpr.get(), found, fn);

  // If desired, do function-to-pointer decay.
  if (doFunctionPointerConverion) {
    SingleFunctionExpression =
      DefaultFunctionArrayLvalueConversion(SingleFunctionExpression.get());
    if (SingleFunctionExpression.isInvalid()) {
      SrcExpr = ExprError();
      return true;
    }
  }
}

if (!SingleFunctionExpression.isUsable()) {
  if (complain) {
    Diag(OpRangeForComplaining.getBegin(), DiagIDForComplaining)
      << ovl.Expression->getName()
      << DestTypeForComplaining
      << OpRangeForComplaining
      << ovl.Expression->getQualifierLoc().getSourceRange();
    NoteAllOverloadCandidates(SrcExpr.get());

    SrcExpr = ExprError();
    return true;
  }

  return false;
}

SrcExpr = SingleFunctionExpression;
return true;
12590}

12592/// Add a single candidate to the overload set.
12593static void AddOverloadedCallCandidate(Sema &S,
                                     DeclAccessPair FoundDecl,
                               TemplateArgumentListInfo *ExplicitTemplateArgs,
                                     ArrayRef<Expr *> Args,
                                     OverloadCandidateSet &CandidateSet,
                                     bool PartialOverloading,
                                     bool KnownValid) {
NamedDecl *Callee = FoundDecl.getDecl();
if (isa<UsingShadowDecl>(Callee))
  Callee = cast<UsingShadowDecl>(Callee)->getTargetDecl();

if (FunctionDecl *Func = dyn_cast<FunctionDecl>(Callee)) {
  if (ExplicitTemplateArgs) {
    assert(!KnownValid && "Explicit template arguments?")((void)0);
    return;
  }
  // Prevent ill-formed function decls to be added as overload candidates.
  if (!dyn_cast<FunctionProtoType>(Func->getType()->getAs<FunctionType>()))
    return;

  S.AddOverloadCandidate(Func, FoundDecl, Args, CandidateSet,
                         /*SuppressUserConversions=*/false,
                         PartialOverloading);
  return;
}

if (FunctionTemplateDecl *FuncTemplate
    = dyn_cast<FunctionTemplateDecl>(Callee)) {
  S.AddTemplateOverloadCandidate(FuncTemplate, FoundDecl,
                                 ExplicitTemplateArgs, Args, CandidateSet,
                                 /*SuppressUserConversions=*/false,
                                 PartialOverloading);
  return;
}

assert(!KnownValid && "unhandled case in overloaded call candidate")((void)0);
12629}

12631/// Add the overload candidates named by callee and/or found by argument
12632/// dependent lookup to the given overload set.
12633void Sema::AddOverloadedCallCandidates(UnresolvedLookupExpr *ULE,
                                     ArrayRef<Expr *> Args,
                                     OverloadCandidateSet &CandidateSet,
                                     bool PartialOverloading) {

12638#ifndef NDEBUG1
// Verify that ArgumentDependentLookup is consistent with the rules
// in C++0x [basic.lookup.argdep]p3:
//
//   Let X be the lookup set produced by unqualified lookup (3.4.1)
//   and let Y be the lookup set produced by argument dependent
//   lookup (defined as follows). If X contains
//
//     -- a declaration of a class member, or
//
//     -- a block-scope function declaration that is not a
//        using-declaration, or
//
//     -- a declaration that is neither a function or a function
//        template
//
//   then Y is empty.

if (ULE->requiresADL()) {
  for (UnresolvedLookupExpr::decls_iterator I = ULE->decls_begin(),
         E = ULE->decls_end(); I != E; ++I) {
    assert(!(*I)->getDeclContext()->isRecord())((void)0);
    assert(isa<UsingShadowDecl>(*I) ||((void)0)
           !(*I)->getDeclContext()->isFunctionOrMethod())((void)0);
    assert((*I)->getUnderlyingDecl()->isFunctionOrFunctionTemplate())((void)0);
  }
}
12665#endif

// It would be nice to avoid this copy.
TemplateArgumentListInfo TABuffer;
TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr;
if (ULE->hasExplicitTemplateArgs()) {
  ULE->copyTemplateArgumentsInto(TABuffer);
  ExplicitTemplateArgs = &TABuffer;
}

for (UnresolvedLookupExpr::decls_iterator I = ULE->decls_begin(),
       E = ULE->decls_end(); I != E; ++I)
  AddOverloadedCallCandidate(*this, I.getPair(), ExplicitTemplateArgs, Args,
                             CandidateSet, PartialOverloading,
                             /*KnownValid*/ true);

if (ULE->requiresADL())
  AddArgumentDependentLookupCandidates(ULE->getName(), ULE->getExprLoc(),
                                       Args, ExplicitTemplateArgs,
                                       CandidateSet, PartialOverloading);
12685}

12687/// Add the call candidates from the given set of lookup results to the given
12688/// overload set. Non-function lookup results are ignored.
12689void Sema::AddOverloadedCallCandidates(
  LookupResult &R, TemplateArgumentListInfo *ExplicitTemplateArgs,
  ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet) {
for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I)
  AddOverloadedCallCandidate(*this, I.getPair(), ExplicitTemplateArgs, Args,
                             CandidateSet, false, /*KnownValid*/ false);
12695}

12697/// Determine whether a declaration with the specified name could be moved into
12698/// a different namespace.
12699static bool canBeDeclaredInNamespace(const DeclarationName &Name) {
switch (Name.getCXXOverloadedOperator()) {
case OO_New: case OO_Array_New:
case OO_Delete: case OO_Array_Delete:
  return false;

default:
  return true;
}
12708}

12710/// Attempt to recover from an ill-formed use of a non-dependent name in a
12711/// template, where the non-dependent name was declared after the template
12712/// was defined. This is common in code written for a compilers which do not
12713/// correctly implement two-stage name lookup.
12714///
12715/// Returns true if a viable candidate was found and a diagnostic was issued.
12716static bool DiagnoseTwoPhaseLookup(
  Sema &SemaRef, SourceLocation FnLoc, const CXXScopeSpec &SS,
  LookupResult &R, OverloadCandidateSet::CandidateSetKind CSK,
  TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
  CXXRecordDecl **FoundInClass = nullptr) {
if (!SemaRef.inTemplateInstantiation() || !SS.isEmpty())
  return false;

for (DeclContext *DC = SemaRef.CurContext; DC; DC = DC->getParent()) {
  if (DC->isTransparentContext())
    continue;

  SemaRef.LookupQualifiedName(R, DC);

  if (!R.empty()) {
    R.suppressDiagnostics();

    OverloadCandidateSet Candidates(FnLoc, CSK);
    SemaRef.AddOverloadedCallCandidates(R, ExplicitTemplateArgs, Args,
                                        Candidates);

    OverloadCandidateSet::iterator Best;
    OverloadingResult OR =
        Candidates.BestViableFunction(SemaRef, FnLoc, Best);

    if (auto *RD = dyn_cast<CXXRecordDecl>(DC)) {
      // We either found non-function declarations or a best viable function
      // at class scope. A class-scope lookup result disables ADL. Don't
      // look past this, but let the caller know that we found something that
      // either is, or might be, usable in this class.
      if (FoundInClass) {
        *FoundInClass = RD;
        if (OR == OR_Success) {
          R.clear();
          R.addDecl(Best->FoundDecl.getDecl(), Best->FoundDecl.getAccess());
          R.resolveKind();
        }
      }
      return false;
    }

    if (OR != OR_Success) {
      // There wasn't a unique best function or function template.
      return false;
    }

    // Find the namespaces where ADL would have looked, and suggest
    // declaring the function there instead.
    Sema::AssociatedNamespaceSet AssociatedNamespaces;
    Sema::AssociatedClassSet AssociatedClasses;
    SemaRef.FindAssociatedClassesAndNamespaces(FnLoc, Args,
                                               AssociatedNamespaces,
                                               AssociatedClasses);
    Sema::AssociatedNamespaceSet SuggestedNamespaces;
    if (canBeDeclaredInNamespace(R.getLookupName())) {
      DeclContext *Std = SemaRef.getStdNamespace();
      for (Sema::AssociatedNamespaceSet::iterator
             it = AssociatedNamespaces.begin(),
             end = AssociatedNamespaces.end(); it != end; ++it) {
        // Never suggest declaring a function within namespace 'std'.
        if (Std && Std->Encloses(*it))
          continue;

        // Never suggest declaring a function within a namespace with a
        // reserved name, like __gnu_cxx.
        NamespaceDecl *NS = dyn_cast<NamespaceDecl>(*it);
        if (NS &&
            NS->getQualifiedNameAsString().find("__") != std::string::npos)
          continue;

        SuggestedNamespaces.insert(*it);
      }
    }

    SemaRef.Diag(R.getNameLoc(), diag::err_not_found_by_two_phase_lookup)
      << R.getLookupName();
    if (SuggestedNamespaces.empty()) {
      SemaRef.Diag(Best->Function->getLocation(),
                   diag::note_not_found_by_two_phase_lookup)
        << R.getLookupName() << 0;
    } else if (SuggestedNamespaces.size() == 1) {
      SemaRef.Diag(Best->Function->getLocation(),
                   diag::note_not_found_by_two_phase_lookup)
        << R.getLookupName() << 1 << *SuggestedNamespaces.begin();
    } else {
      // FIXME: It would be useful to list the associated namespaces here,
      // but the diagnostics infrastructure doesn't provide a way to produce
      // a localized representation of a list of items.
      SemaRef.Diag(Best->Function->getLocation(),
                   diag::note_not_found_by_two_phase_lookup)
        << R.getLookupName() << 2;
    }

    // Try to recover by calling this function.
    return true;
  }

  R.clear();
}

return false;
12817}

12819/// Attempt to recover from ill-formed use of a non-dependent operator in a
12820/// template, where the non-dependent operator was declared after the template
12821/// was defined.
12822///
12823/// Returns true if a viable candidate was found and a diagnostic was issued.
12824static bool
12825DiagnoseTwoPhaseOperatorLookup(Sema &SemaRef, OverloadedOperatorKind Op,
                             SourceLocation OpLoc,
                             ArrayRef<Expr *> Args) {
DeclarationName OpName =
  SemaRef.Context.DeclarationNames.getCXXOperatorName(Op);
LookupResult R(SemaRef, OpName, OpLoc, Sema::LookupOperatorName);
return DiagnoseTwoPhaseLookup(SemaRef, OpLoc, CXXScopeSpec(), R,
                              OverloadCandidateSet::CSK_Operator,
                              /*ExplicitTemplateArgs=*/nullptr, Args);
12834}

12836namespace {
12837class BuildRecoveryCallExprRAII {
Sema &SemaRef;
12839public:
BuildRecoveryCallExprRAII(Sema &S) : SemaRef(S) {
  assert(SemaRef.IsBuildingRecoveryCallExpr == false)((void)0);
  SemaRef.IsBuildingRecoveryCallExpr = true;
}

~BuildRecoveryCallExprRAII() {
  SemaRef.IsBuildingRecoveryCallExpr = false;
}
12848};

12850}

12852/// Attempts to recover from a call where no functions were found.
12853///
12854/// This function will do one of three things:
12855///  * Diagnose, recover, and return a recovery expression.
12856///  * Diagnose, fail to recover, and return ExprError().
12857///  * Do not diagnose, do not recover, and return ExprResult(). The caller is
12858///    expected to diagnose as appropriate.
12859static ExprResult
12860BuildRecoveryCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
                    UnresolvedLookupExpr *ULE,
                    SourceLocation LParenLoc,
                    MutableArrayRef<Expr *> Args,
                    SourceLocation RParenLoc,
                    bool EmptyLookup, bool AllowTypoCorrection) {
// Do not try to recover if it is already building a recovery call.
// This stops infinite loops for template instantiations like
//
// template <typename T> auto foo(T t) -> decltype(foo(t)) {}
// template <typename T> auto foo(T t) -> decltype(foo(&t)) {}
if (SemaRef.IsBuildingRecoveryCallExpr)
  return ExprResult();
BuildRecoveryCallExprRAII RCE(SemaRef);

CXXScopeSpec SS;
SS.Adopt(ULE->getQualifierLoc());
SourceLocation TemplateKWLoc = ULE->getTemplateKeywordLoc();

TemplateArgumentListInfo TABuffer;
TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr;
if (ULE->hasExplicitTemplateArgs()) {
  ULE->copyTemplateArgumentsInto(TABuffer);
  ExplicitTemplateArgs = &TABuffer;
}

LookupResult R(SemaRef, ULE->getName(), ULE->getNameLoc(),
               Sema::LookupOrdinaryName);
CXXRecordDecl *FoundInClass = nullptr;
if (DiagnoseTwoPhaseLookup(SemaRef, Fn->getExprLoc(), SS, R,
                           OverloadCandidateSet::CSK_Normal,
                           ExplicitTemplateArgs, Args, &FoundInClass)) {
  // OK, diagnosed a two-phase lookup issue.
} else if (EmptyLookup) {
  // Try to recover from an empty lookup with typo correction.
  R.clear();
  NoTypoCorrectionCCC NoTypoValidator{};
  FunctionCallFilterCCC FunctionCallValidator(SemaRef, Args.size(),
                                              ExplicitTemplateArgs != nullptr,
                                              dyn_cast<MemberExpr>(Fn));
  CorrectionCandidateCallback &Validator =
      AllowTypoCorrection
          ? static_cast<CorrectionCandidateCallback &>(FunctionCallValidator)
          : static_cast<CorrectionCandidateCallback &>(NoTypoValidator);
  if (SemaRef.DiagnoseEmptyLookup(S, SS, R, Validator, ExplicitTemplateArgs,
                                  Args))
    return ExprError();
} else if (FoundInClass && SemaRef.getLangOpts().MSVCCompat) {
  // We found a usable declaration of the name in a dependent base of some
  // enclosing class.
  // FIXME: We should also explain why the candidates found by name lookup
  // were not viable.
  if (SemaRef.DiagnoseDependentMemberLookup(R))
    return ExprError();
} else {
  // We had viable candidates and couldn't recover; let the caller diagnose
  // this.
  return ExprResult();
}

// If we get here, we should have issued a diagnostic and formed a recovery
// lookup result.
assert(!R.empty() && "lookup results empty despite recovery")((void)0);

// If recovery created an ambiguity, just bail out.
if (R.isAmbiguous()) {
  R.suppressDiagnostics();
  return ExprError();
}

// Build an implicit member call if appropriate.  Just drop the
// casts and such from the call, we don't really care.
ExprResult NewFn = ExprError();
if ((*R.begin())->isCXXClassMember())
  NewFn = SemaRef.BuildPossibleImplicitMemberExpr(SS, TemplateKWLoc, R,
                                                  ExplicitTemplateArgs, S);
else if (ExplicitTemplateArgs || TemplateKWLoc.isValid())
  NewFn = SemaRef.BuildTemplateIdExpr(SS, TemplateKWLoc, R, false,
                                      ExplicitTemplateArgs);
else
  NewFn = SemaRef.BuildDeclarationNameExpr(SS, R, false);

if (NewFn.isInvalid())
  return ExprError();

// This shouldn't cause an infinite loop because we're giving it
// an expression with viable lookup results, which should never
// end up here.
return SemaRef.BuildCallExpr(/*Scope*/ nullptr, NewFn.get(), LParenLoc,
                             MultiExprArg(Args.data(), Args.size()),
                             RParenLoc);
12951}

12953/// Constructs and populates an OverloadedCandidateSet from
12954/// the given function.
12955/// \returns true when an the ExprResult output parameter has been set.
12956bool Sema::buildOverloadedCallSet(Scope *S, Expr *Fn,
                                UnresolvedLookupExpr *ULE,
                                MultiExprArg Args,
                                SourceLocation RParenLoc,
                                OverloadCandidateSet *CandidateSet,
                                ExprResult *Result) {
12962#ifndef NDEBUG1
if (ULE->requiresADL()) {
  // To do ADL, we must have found an unqualified name.
  assert(!ULE->getQualifier() && "qualified name with ADL")((void)0);

  // We don't perform ADL for implicit declarations of builtins.
  // Verify that this was correctly set up.
  FunctionDecl *F;
  if (ULE->decls_begin() != ULE->decls_end() &&
      ULE->decls_begin() + 1 == ULE->decls_end() &&
      (F = dyn_cast<FunctionDecl>(*ULE->decls_begin())) &&
      F->getBuiltinID() && F->isImplicit())
    llvm_unreachable("performing ADL for builtin")__builtin_unreachable();

  // We don't perform ADL in C.
  assert(getLangOpts().CPlusPlus && "ADL enabled in C")((void)0);
}
12979#endif

UnbridgedCastsSet UnbridgedCasts;
if (checkArgPlaceholdersForOverload(*this, Args, UnbridgedCasts)) {
  *Result = ExprError();
  return true;
}

// Add the functions denoted by the callee to the set of candidate
// functions, including those from argument-dependent lookup.
AddOverloadedCallCandidates(ULE, Args, *CandidateSet);

if (getLangOpts().MSVCCompat &&
    CurContext->isDependentContext() && !isSFINAEContext() &&
    (isa<FunctionDecl>(CurContext) || isa<CXXRecordDecl>(CurContext))) {

  OverloadCandidateSet::iterator Best;
  if (CandidateSet->empty() ||
      CandidateSet->BestViableFunction(*this, Fn->getBeginLoc(), Best) ==
          OR_No_Viable_Function) {
    // In Microsoft mode, if we are inside a template class member function
    // then create a type dependent CallExpr. The goal is to postpone name
    // lookup to instantiation time to be able to search into type dependent
    // base classes.
    CallExpr *CE =
        CallExpr::Create(Context, Fn, Args, Context.DependentTy, VK_PRValue,
                         RParenLoc, CurFPFeatureOverrides());
    CE->markDependentForPostponedNameLookup();
    *Result = CE;
    return true;
  }
}

if (CandidateSet->empty())
  return false;

UnbridgedCasts.restore();
return false;
13017}

13019// Guess at what the return type for an unresolvable overload should be.
13020static QualType chooseRecoveryType(OverloadCandidateSet &CS,
                                 OverloadCandidateSet::iterator *Best) {
llvm::Optional<QualType> Result;
// Adjust Type after seeing a candidate.
auto ConsiderCandidate = [&](const OverloadCandidate &Candidate) {
  if (!Candidate.Function)
    return;
  if (Candidate.Function->isInvalidDecl())
    return;
  QualType T = Candidate.Function->getReturnType();
  if (T.isNull())
    return;
  if (!Result)
    Result = T;
  else if (Result != T)
    Result = QualType();
};

// Look for an unambiguous type from a progressively larger subset.
// e.g. if types disagree, but all *viable* overloads return int, choose int.
//
// First, consider only the best candidate.
if (Best && *Best != CS.end())
  ConsiderCandidate(**Best);
// Next, consider only viable candidates.
if (!Result)
  for (const auto &C : CS)
    if (C.Viable)
      ConsiderCandidate(C);
// Finally, consider all candidates.
if (!Result)
  for (const auto &C : CS)
    ConsiderCandidate(C);

if (!Result)
  return QualType();
auto Value = Result.getValue();
if (Value.isNull() || Value->isUndeducedType())
  return QualType();
return Value;
13060}

13062/// FinishOverloadedCallExpr - given an OverloadCandidateSet, builds and returns
13063/// the completed call expression. If overload resolution fails, emits
13064/// diagnostics and returns ExprError()
13065static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
                                         UnresolvedLookupExpr *ULE,
                                         SourceLocation LParenLoc,
                                         MultiExprArg Args,
                                         SourceLocation RParenLoc,
                                         Expr *ExecConfig,
                                         OverloadCandidateSet *CandidateSet,
                                         OverloadCandidateSet::iterator *Best,
                                         OverloadingResult OverloadResult,
                                         bool AllowTypoCorrection) {
switch (OverloadResult) {
case OR_Success: {
  FunctionDecl *FDecl = (*Best)->Function;
  SemaRef.CheckUnresolvedLookupAccess(ULE, (*Best)->FoundDecl);
  if (SemaRef.DiagnoseUseOfDecl(FDecl, ULE->getNameLoc()))
    return ExprError();
  Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
  return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
                                       ExecConfig, /*IsExecConfig=*/false,
                                       (*Best)->IsADLCandidate);
}

case OR_No_Viable_Function: {
  // Try to recover by looking for viable functions which the user might
  // have meant to call.
  ExprResult Recovery = BuildRecoveryCallExpr(SemaRef, S, Fn, ULE, LParenLoc,
                                              Args, RParenLoc,
                                              CandidateSet->empty(),
                                              AllowTypoCorrection);
  if (Recovery.isInvalid() || Recovery.isUsable())
    return Recovery;

  // If the user passes in a function that we can't take the address of, we
  // generally end up emitting really bad error messages. Here, we attempt to
  // emit better ones.
  for (const Expr *Arg : Args) {
    if (!Arg->getType()->isFunctionType())
      continue;
    if (auto *DRE = dyn_cast<DeclRefExpr>(Arg->IgnoreParenImpCasts())) {
      auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
      if (FD &&
          !SemaRef.checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
                                                     Arg->getExprLoc()))
        return ExprError();
    }
  }

  CandidateSet->NoteCandidates(
      PartialDiagnosticAt(
          Fn->getBeginLoc(),
          SemaRef.PDiag(diag::err_ovl_no_viable_function_in_call)
              << ULE->getName() << Fn->getSourceRange()),
      SemaRef, OCD_AllCandidates, Args);
  break;
}

case OR_Ambiguous:
  CandidateSet->NoteCandidates(
      PartialDiagnosticAt(Fn->getBeginLoc(),
                          SemaRef.PDiag(diag::err_ovl_ambiguous_call)
                              << ULE->getName() << Fn->getSourceRange()),
      SemaRef, OCD_AmbiguousCandidates, Args);
  break;

case OR_Deleted: {
  CandidateSet->NoteCandidates(
      PartialDiagnosticAt(Fn->getBeginLoc(),
                          SemaRef.PDiag(diag::err_ovl_deleted_call)
                              << ULE->getName() << Fn->getSourceRange()),
      SemaRef, OCD_AllCandidates, Args);

  // We emitted an error for the unavailable/deleted function call but keep
  // the call in the AST.
  FunctionDecl *FDecl = (*Best)->Function;
  Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
  return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
                                       ExecConfig, /*IsExecConfig=*/false,
                                       (*Best)->IsADLCandidate);
}
}

// Overload resolution failed, try to recover.
SmallVector<Expr *, 8> SubExprs = {Fn};
SubExprs.append(Args.begin(), Args.end());
return SemaRef.CreateRecoveryExpr(Fn->getBeginLoc(), RParenLoc, SubExprs,
                                  chooseRecoveryType(*CandidateSet, Best));
13151}

13153static void markUnaddressableCandidatesUnviable(Sema &S,
                                              OverloadCandidateSet &CS) {
for (auto I = CS.begin(), E = CS.end(); I != E; ++I) {
  if (I->Viable &&
      !S.checkAddressOfFunctionIsAvailable(I->Function, /*Complain=*/false)) {
    I->Viable = false;
    I->FailureKind = ovl_fail_addr_not_available;
  }
}
13162}

13164/// BuildOverloadedCallExpr - Given the call expression that calls Fn
13165/// (which eventually refers to the declaration Func) and the call
13166/// arguments Args/NumArgs, attempt to resolve the function call down
13167/// to a specific function. If overload resolution succeeds, returns
13168/// the call expression produced by overload resolution.
13169/// Otherwise, emits diagnostics and returns ExprError.
13170ExprResult Sema::BuildOverloadedCallExpr(Scope *S, Expr *Fn,
                                       UnresolvedLookupExpr *ULE,
                                       SourceLocation LParenLoc,
                                       MultiExprArg Args,
                                       SourceLocation RParenLoc,
                                       Expr *ExecConfig,
                                       bool AllowTypoCorrection,
                                       bool CalleesAddressIsTaken) {
OverloadCandidateSet CandidateSet(Fn->getExprLoc(),
                                  OverloadCandidateSet::CSK_Normal);
ExprResult result;

if (buildOverloadedCallSet(S, Fn, ULE, Args, LParenLoc, &CandidateSet,
                           &result))
  return result;

// If the user handed us something like `(&Foo)(Bar)`, we need to ensure that
// functions that aren't addressible are considered unviable.
if (CalleesAddressIsTaken)
  markUnaddressableCandidatesUnviable(*this, CandidateSet);

OverloadCandidateSet::iterator Best;
OverloadingResult OverloadResult =
    CandidateSet.BestViableFunction(*this, Fn->getBeginLoc(), Best);

return FinishOverloadedCallExpr(*this, S, Fn, ULE, LParenLoc, Args, RParenLoc,
                                ExecConfig, &CandidateSet, &Best,
                                OverloadResult, AllowTypoCorrection);
13198}

13200static bool IsOverloaded(const UnresolvedSetImpl &Functions) {
return Functions.size() > 1 ||
       (Functions.size() == 1 &&
        isa<FunctionTemplateDecl>((*Functions.begin())->getUnderlyingDecl()));
13204}

13206ExprResult Sema::CreateUnresolvedLookupExpr(CXXRecordDecl *NamingClass,
                                          NestedNameSpecifierLoc NNSLoc,
                                          DeclarationNameInfo DNI,
                                          const UnresolvedSetImpl &Fns,
                                          bool PerformADL) {
return UnresolvedLookupExpr::Create(Context, NamingClass, NNSLoc, DNI,
                                    PerformADL, IsOverloaded(Fns),
                                    Fns.begin(), Fns.end());
13214}

13216/// Create a unary operation that may resolve to an overloaded
13217/// operator.
13218///
13219/// \param OpLoc The location of the operator itself (e.g., '*').
13220///
13221/// \param Opc The UnaryOperatorKind that describes this operator.
13222///
13223/// \param Fns The set of non-member functions that will be
13224/// considered by overload resolution. The caller needs to build this
13225/// set based on the context using, e.g.,
13226/// LookupOverloadedOperatorName() and ArgumentDependentLookup(). This
13227/// set should not contain any member functions; those will be added
13228/// by CreateOverloadedUnaryOp().
13229///
13230/// \param Input The input argument.
13231ExprResult
13232Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
                            const UnresolvedSetImpl &Fns,
                            Expr *Input, bool PerformADL) {
OverloadedOperatorKind Op = UnaryOperator::getOverloadedOperator(Opc);
assert(Op != OO_None && "Invalid opcode for overloaded unary operator")((void)0);
DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
// TODO: provide better source location info.
DeclarationNameInfo OpNameInfo(OpName, OpLoc);

if (checkPlaceholderForOverload(*this, Input))
  return ExprError();

Expr *Args[2] = { Input, nullptr };
unsigned NumArgs = 1;

// For post-increment and post-decrement, add the implicit '0' as
// the second argument, so that we know this is a post-increment or
// post-decrement.
if (Opc == UO_PostInc || Opc == UO_PostDec) {
  llvm::APSInt Zero(Context.getTypeSize(Context.IntTy), false);
  Args[1] = IntegerLiteral::Create(Context, Zero, Context.IntTy,
                                   SourceLocation());
  NumArgs = 2;
}

ArrayRef<Expr *> ArgsArray(Args, NumArgs);

if (Input->isTypeDependent()) {
  if (Fns.empty())
    return UnaryOperator::Create(Context, Input, Opc, Context.DependentTy,
                                 VK_PRValue, OK_Ordinary, OpLoc, false,
                                 CurFPFeatureOverrides());

  CXXRecordDecl *NamingClass = nullptr; // lookup ignores member operators
  ExprResult Fn = CreateUnresolvedLookupExpr(
      NamingClass, NestedNameSpecifierLoc(), OpNameInfo, Fns);
  if (Fn.isInvalid())
    return ExprError();
  return CXXOperatorCallExpr::Create(Context, Op, Fn.get(), ArgsArray,
                                     Context.DependentTy, VK_PRValue, OpLoc,
                                     CurFPFeatureOverrides());
}

// Build an empty overload set.
OverloadCandidateSet CandidateSet(OpLoc, OverloadCandidateSet::CSK_Operator);

// Add the candidates from the given function set.
AddNonMemberOperatorCandidates(Fns, ArgsArray, CandidateSet);

// Add operator candidates that are member functions.
AddMemberOperatorCandidates(Op, OpLoc, ArgsArray, CandidateSet);

// Add candidates from ADL.
if (PerformADL) {
  AddArgumentDependentLookupCandidates(OpName, OpLoc, ArgsArray,
                                       /*ExplicitTemplateArgs*/nullptr,
                                       CandidateSet);
}

// Add builtin operator candidates.
AddBuiltinOperatorCandidates(Op, OpLoc, ArgsArray, CandidateSet);

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, OpLoc, Best)) {
case OR_Success: {
  // We found a built-in operator or an overloaded operator.
  FunctionDecl *FnDecl = Best->Function;

  if (FnDecl) {
    Expr *Base = nullptr;
    // We matched an overloaded operator. Build a call to that
    // operator.

    // Convert the arguments.
    if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
      CheckMemberOperatorAccess(OpLoc, Args[0], nullptr, Best->FoundDecl);

      ExprResult InputRes =
        PerformObjectArgumentInitialization(Input, /*Qualifier=*/nullptr,
                                            Best->FoundDecl, Method);
      if (InputRes.isInvalid())
        return ExprError();
      Base = Input = InputRes.get();
    } else {
      // Convert the arguments.
      ExprResult InputInit
        = PerformCopyInitialization(InitializedEntity::InitializeParameter(
                                                    Context,
                                                    FnDecl->getParamDecl(0)),
                                    SourceLocation(),
                                    Input);
      if (InputInit.isInvalid())
        return ExprError();
      Input = InputInit.get();
    }

    // Build the actual expression node.
    ExprResult FnExpr = CreateFunctionRefExpr(*this, FnDecl, Best->FoundDecl,
                                              Base, HadMultipleCandidates,
                                              OpLoc);
    if (FnExpr.isInvalid())
      return ExprError();

    // Determine the result type.
    QualType ResultTy = FnDecl->getReturnType();
    ExprValueKind VK = Expr::getValueKindForType(ResultTy);
    ResultTy = ResultTy.getNonLValueExprType(Context);

    Args[0] = Input;
    CallExpr *TheCall = CXXOperatorCallExpr::Create(
        Context, Op, FnExpr.get(), ArgsArray, ResultTy, VK, OpLoc,
        CurFPFeatureOverrides(), Best->IsADLCandidate);

    if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall, FnDecl))
      return ExprError();

    if (CheckFunctionCall(FnDecl, TheCall,
                          FnDecl->getType()->castAs<FunctionProtoType>()))
      return ExprError();
    return CheckForImmediateInvocation(MaybeBindToTemporary(TheCall), FnDecl);
  } else {
    // We matched a built-in operator. Convert the arguments, then
    // break out so that we will build the appropriate built-in
    // operator node.
    ExprResult InputRes = PerformImplicitConversion(
        Input, Best->BuiltinParamTypes[0], Best->Conversions[0], AA_Passing,
        CCK_ForBuiltinOverloadedOp);
    if (InputRes.isInvalid())
      return ExprError();
    Input = InputRes.get();
    break;
  }
}

case OR_No_Viable_Function:
  // This is an erroneous use of an operator which can be overloaded by
  // a non-member function. Check for non-member operators which were
  // defined too late to be candidates.
  if (DiagnoseTwoPhaseOperatorLookup(*this, Op, OpLoc, ArgsArray))
    // FIXME: Recover by calling the found function.
    return ExprError();

  // No viable function; fall through to handling this as a
  // built-in operator, which will produce an error message for us.
  break;

case OR_Ambiguous:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(OpLoc,
                          PDiag(diag::err_ovl_ambiguous_oper_unary)
                              << UnaryOperator::getOpcodeStr(Opc)
                              << Input->getType() << Input->getSourceRange()),
      *this, OCD_AmbiguousCandidates, ArgsArray,
      UnaryOperator::getOpcodeStr(Opc), OpLoc);
  return ExprError();

case OR_Deleted:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(OpLoc, PDiag(diag::err_ovl_deleted_oper)
                                     << UnaryOperator::getOpcodeStr(Opc)
                                     << Input->getSourceRange()),
      *this, OCD_AllCandidates, ArgsArray, UnaryOperator::getOpcodeStr(Opc),
      OpLoc);
  return ExprError();
}

// Either we found no viable overloaded operator or we matched a
// built-in operator. In either case, fall through to trying to
// build a built-in operation.
return CreateBuiltinUnaryOp(OpLoc, Opc, Input);
13405}

13407/// Perform lookup for an overloaded binary operator.
13408void Sema::LookupOverloadedBinOp(OverloadCandidateSet &CandidateSet,
                               OverloadedOperatorKind Op,
                               const UnresolvedSetImpl &Fns,
                               ArrayRef<Expr *> Args, bool PerformADL) {
SourceLocation OpLoc = CandidateSet.getLocation();

OverloadedOperatorKind ExtraOp =
    CandidateSet.getRewriteInfo().AllowRewrittenCandidates
        ? getRewrittenOverloadedOperator(Op)
        : OO_None;

// Add the candidates from the given function set. This also adds the
// rewritten candidates using these functions if necessary.
AddNonMemberOperatorCandidates(Fns, Args, CandidateSet);

// Add operator candidates that are member functions.
AddMemberOperatorCandidates(Op, OpLoc, Args, CandidateSet);
if (CandidateSet.getRewriteInfo().shouldAddReversed(Op))
  AddMemberOperatorCandidates(Op, OpLoc, {Args[1], Args[0]}, CandidateSet,
                              OverloadCandidateParamOrder::Reversed);

// In C++20, also add any rewritten member candidates.
if (ExtraOp) {
  AddMemberOperatorCandidates(ExtraOp, OpLoc, Args, CandidateSet);
  if (CandidateSet.getRewriteInfo().shouldAddReversed(ExtraOp))
    AddMemberOperatorCandidates(ExtraOp, OpLoc, {Args[1], Args[0]},
                                CandidateSet,
                                OverloadCandidateParamOrder::Reversed);
}

// Add candidates from ADL. Per [over.match.oper]p2, this lookup is not
// performed for an assignment operator (nor for operator[] nor operator->,
// which don't get here).
if (Op != OO_Equal && PerformADL) {
  DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
  AddArgumentDependentLookupCandidates(OpName, OpLoc, Args,
                                       /*ExplicitTemplateArgs*/ nullptr,
                                       CandidateSet);
  if (ExtraOp) {
    DeclarationName ExtraOpName =
        Context.DeclarationNames.getCXXOperatorName(ExtraOp);
    AddArgumentDependentLookupCandidates(ExtraOpName, OpLoc, Args,
                                         /*ExplicitTemplateArgs*/ nullptr,
                                         CandidateSet);
  }
}

// Add builtin operator candidates.
//
// FIXME: We don't add any rewritten candidates here. This is strictly
// incorrect; a builtin candidate could be hidden by a non-viable candidate,
// resulting in our selecting a rewritten builtin candidate. For example:
//
//   enum class E { e };
//   bool operator!=(E, E) requires false;
//   bool k = E::e != E::e;
//
// ... should select the rewritten builtin candidate 'operator==(E, E)'. But
// it seems unreasonable to consider rewritten builtin candidates. A core
// issue has been filed proposing to removed this requirement.
AddBuiltinOperatorCandidates(Op, OpLoc, Args, CandidateSet);
13469}

13471/// Create a binary operation that may resolve to an overloaded
13472/// operator.
13473///
13474/// \param OpLoc The location of the operator itself (e.g., '+').
13475///
13476/// \param Opc The BinaryOperatorKind that describes this operator.
13477///
13478/// \param Fns The set of non-member functions that will be
13479/// considered by overload resolution. The caller needs to build this
13480/// set based on the context using, e.g.,
13481/// LookupOverloadedOperatorName() and ArgumentDependentLookup(). This
13482/// set should not contain any member functions; those will be added
13483/// by CreateOverloadedBinOp().
13484///
13485/// \param LHS Left-hand argument.
13486/// \param RHS Right-hand argument.
13487/// \param PerformADL Whether to consider operator candidates found by ADL.
13488/// \param AllowRewrittenCandidates Whether to consider candidates found by
13489///        C++20 operator rewrites.
13490/// \param DefaultedFn If we are synthesizing a defaulted operator function,
13491///        the function in question. Such a function is never a candidate in
13492///        our overload resolution. This also enables synthesizing a three-way
13493///        comparison from < and == as described in C++20 [class.spaceship]p1.
13494ExprResult Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
                                     BinaryOperatorKind Opc,
                                     const UnresolvedSetImpl &Fns, Expr *LHS,
                                     Expr *RHS, bool PerformADL,
                                     bool AllowRewrittenCandidates,
                                     FunctionDecl *DefaultedFn) {
Expr *Args[2] = { LHS, RHS };
LHS=RHS=nullptr; // Please use only Args instead of LHS/RHS couple

if (!getLangOpts().CPlusPlus20)
  AllowRewrittenCandidates = false;

OverloadedOperatorKind Op = BinaryOperator::getOverloadedOperator(Opc);

// If either side is type-dependent, create an appropriate dependent
// expression.
if (Args[0]->isTypeDependent() || Args[1]->isTypeDependent()) {
  if (Fns.empty()) {
    // If there are no functions to store, just build a dependent
    // BinaryOperator or CompoundAssignment.
    if (BinaryOperator::isCompoundAssignmentOp(Opc))
      return CompoundAssignOperator::Create(
          Context, Args[0], Args[1], Opc, Context.DependentTy, VK_LValue,
          OK_Ordinary, OpLoc, CurFPFeatureOverrides(), Context.DependentTy,
          Context.DependentTy);
    return BinaryOperator::Create(
        Context, Args[0], Args[1], Opc, Context.DependentTy, VK_PRValue,
        OK_Ordinary, OpLoc, CurFPFeatureOverrides());
  }

  // FIXME: save results of ADL from here?
  CXXRecordDecl *NamingClass = nullptr; // lookup ignores member operators
  // TODO: provide better source location info in DNLoc component.
  DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(Op);
  DeclarationNameInfo OpNameInfo(OpName, OpLoc);
  ExprResult Fn = CreateUnresolvedLookupExpr(
      NamingClass, NestedNameSpecifierLoc(), OpNameInfo, Fns, PerformADL);
  if (Fn.isInvalid())
    return ExprError();
  return CXXOperatorCallExpr::Create(Context, Op, Fn.get(), Args,
                                     Context.DependentTy, VK_PRValue, OpLoc,
                                     CurFPFeatureOverrides());
}

// Always do placeholder-like conversions on the RHS.
if (checkPlaceholderForOverload(*this, Args[1]))
  return ExprError();

// Do placeholder-like conversion on the LHS; note that we should
// not get here with a PseudoObject LHS.
assert(Args[0]->getObjectKind() != OK_ObjCProperty)((void)0);
if (checkPlaceholderForOverload(*this, Args[0]))
  return ExprError();

// If this is the assignment operator, we only perform overload resolution
// if the left-hand side is a class or enumeration type. This is actually
// a hack. The standard requires that we do overload resolution between the
// various built-in candidates, but as DR507 points out, this can lead to
// problems. So we do it this way, which pretty much follows what GCC does.
// Note that we go the traditional code path for compound assignment forms.
if (Opc == BO_Assign && !Args[0]->getType()->isOverloadableType())
  return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);

// If this is the .* operator, which is not overloadable, just
// create a built-in binary operator.
if (Opc == BO_PtrMemD)
  return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);

// Build the overload set.
OverloadCandidateSet CandidateSet(
    OpLoc, OverloadCandidateSet::CSK_Operator,
    OverloadCandidateSet::OperatorRewriteInfo(Op, AllowRewrittenCandidates));
if (DefaultedFn)
  CandidateSet.exclude(DefaultedFn);
LookupOverloadedBinOp(CandidateSet, Op, Fns, Args, PerformADL);

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, OpLoc, Best)) {
  case OR_Success: {
    // We found a built-in operator or an overloaded operator.
    FunctionDecl *FnDecl = Best->Function;

    bool IsReversed = Best->isReversed();
    if (IsReversed)
      std::swap(Args[0], Args[1]);

    if (FnDecl) {
      Expr *Base = nullptr;
      // We matched an overloaded operator. Build a call to that
      // operator.

      OverloadedOperatorKind ChosenOp =
          FnDecl->getDeclName().getCXXOverloadedOperator();

      // C++2a [over.match.oper]p9:
      //   If a rewritten operator== candidate is selected by overload
      //   resolution for an operator@, its return type shall be cv bool
      if (Best->RewriteKind && ChosenOp == OO_EqualEqual &&
          !FnDecl->getReturnType()->isBooleanType()) {
        bool IsExtension =
            FnDecl->getReturnType()->isIntegralOrUnscopedEnumerationType();
        Diag(OpLoc, IsExtension ? diag::ext_ovl_rewrite_equalequal_not_bool
                                : diag::err_ovl_rewrite_equalequal_not_bool)
            << FnDecl->getReturnType() << BinaryOperator::getOpcodeStr(Opc)
            << Args[0]->getSourceRange() << Args[1]->getSourceRange();
        Diag(FnDecl->getLocation(), diag::note_declared_at);
        if (!IsExtension)
          return ExprError();
      }

      if (AllowRewrittenCandidates && !IsReversed &&
          CandidateSet.getRewriteInfo().isReversible()) {
        // We could have reversed this operator, but didn't. Check if some
        // reversed form was a viable candidate, and if so, if it had a
        // better conversion for either parameter. If so, this call is
        // formally ambiguous, and allowing it is an extension.
        llvm::SmallVector<FunctionDecl*, 4> AmbiguousWith;
        for (OverloadCandidate &Cand : CandidateSet) {
          if (Cand.Viable && Cand.Function && Cand.isReversed() &&
              haveSameParameterTypes(Context, Cand.Function, FnDecl, 2)) {
            for (unsigned ArgIdx = 0; ArgIdx < 2; ++ArgIdx) {
              if (CompareImplicitConversionSequences(
                      *this, OpLoc, Cand.Conversions[ArgIdx],
                      Best->Conversions[ArgIdx]) ==
                  ImplicitConversionSequence::Better) {
                AmbiguousWith.push_back(Cand.Function);
                break;
              }
            }
          }
        }

        if (!AmbiguousWith.empty()) {
          bool AmbiguousWithSelf =
              AmbiguousWith.size() == 1 &&
              declaresSameEntity(AmbiguousWith.front(), FnDecl);
          Diag(OpLoc, diag::ext_ovl_ambiguous_oper_binary_reversed)
              << BinaryOperator::getOpcodeStr(Opc)
              << Args[0]->getType() << Args[1]->getType() << AmbiguousWithSelf
              << Args[0]->getSourceRange() << Args[1]->getSourceRange();
          if (AmbiguousWithSelf) {
            Diag(FnDecl->getLocation(),
                 diag::note_ovl_ambiguous_oper_binary_reversed_self);
          } else {
            Diag(FnDecl->getLocation(),
                 diag::note_ovl_ambiguous_oper_binary_selected_candidate);
            for (auto *F : AmbiguousWith)
              Diag(F->getLocation(),
                   diag::note_ovl_ambiguous_oper_binary_reversed_candidate);
          }
        }
      }

      // Convert the arguments.
      if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FnDecl)) {
        // Best->Access is only meaningful for class members.
        CheckMemberOperatorAccess(OpLoc, Args[0], Args[1], Best->FoundDecl);

        ExprResult Arg1 =
          PerformCopyInitialization(
            InitializedEntity::InitializeParameter(Context,
                                                   FnDecl->getParamDecl(0)),
            SourceLocation(), Args[1]);
        if (Arg1.isInvalid())
          return ExprError();

        ExprResult Arg0 =
          PerformObjectArgumentInitialization(Args[0], /*Qualifier=*/nullptr,
                                              Best->FoundDecl, Method);
        if (Arg0.isInvalid())
          return ExprError();
        Base = Args[0] = Arg0.getAs<Expr>();
        Args[1] = RHS = Arg1.getAs<Expr>();
      } else {
        // Convert the arguments.
        ExprResult Arg0 = PerformCopyInitialization(
          InitializedEntity::InitializeParameter(Context,
                                                 FnDecl->getParamDecl(0)),
          SourceLocation(), Args[0]);
        if (Arg0.isInvalid())
          return ExprError();

        ExprResult Arg1 =
          PerformCopyInitialization(
            InitializedEntity::InitializeParameter(Context,
                                                   FnDecl->getParamDecl(1)),
            SourceLocation(), Args[1]);
        if (Arg1.isInvalid())
          return ExprError();
        Args[0] = LHS = Arg0.getAs<Expr>();
        Args[1] = RHS = Arg1.getAs<Expr>();
      }

      // Build the actual expression node.
      ExprResult FnExpr = CreateFunctionRefExpr(*this, FnDecl,
                                                Best->FoundDecl, Base,
                                                HadMultipleCandidates, OpLoc);
      if (FnExpr.isInvalid())
        return ExprError();

      // Determine the result type.
      QualType ResultTy = FnDecl->getReturnType();
      ExprValueKind VK = Expr::getValueKindForType(ResultTy);
      ResultTy = ResultTy.getNonLValueExprType(Context);

      CXXOperatorCallExpr *TheCall = CXXOperatorCallExpr::Create(
          Context, ChosenOp, FnExpr.get(), Args, ResultTy, VK, OpLoc,
          CurFPFeatureOverrides(), Best->IsADLCandidate);

      if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall,
                              FnDecl))
        return ExprError();

      ArrayRef<const Expr *> ArgsArray(Args, 2);
      const Expr *ImplicitThis = nullptr;
      // Cut off the implicit 'this'.
      if (isa<CXXMethodDecl>(FnDecl)) {
        ImplicitThis = ArgsArray[0];
        ArgsArray = ArgsArray.slice(1);
      }

      // Check for a self move.
      if (Op == OO_Equal)
        DiagnoseSelfMove(Args[0], Args[1], OpLoc);

      if (ImplicitThis) {
        QualType ThisType = Context.getPointerType(ImplicitThis->getType());
        QualType ThisTypeFromDecl = Context.getPointerType(
            cast<CXXMethodDecl>(FnDecl)->getThisObjectType());

        CheckArgAlignment(OpLoc, FnDecl, "'this'", ThisType,
                          ThisTypeFromDecl);
      }

      checkCall(FnDecl, nullptr, ImplicitThis, ArgsArray,
                isa<CXXMethodDecl>(FnDecl), OpLoc, TheCall->getSourceRange(),
                VariadicDoesNotApply);

      ExprResult R = MaybeBindToTemporary(TheCall);
      if (R.isInvalid())
        return ExprError();

      R = CheckForImmediateInvocation(R, FnDecl);
      if (R.isInvalid())
        return ExprError();

      // For a rewritten candidate, we've already reversed the arguments
      // if needed. Perform the rest of the rewrite now.
      if ((Best->RewriteKind & CRK_DifferentOperator) ||
          (Op == OO_Spaceship && IsReversed)) {
        if (Op == OO_ExclaimEqual) {
          assert(ChosenOp == OO_EqualEqual && "unexpected operator name")((void)0);
          R = CreateBuiltinUnaryOp(OpLoc, UO_LNot, R.get());
        } else {
          assert(ChosenOp == OO_Spaceship && "unexpected operator name")((void)0);
          llvm::APSInt Zero(Context.getTypeSize(Context.IntTy), false);
          Expr *ZeroLiteral =
              IntegerLiteral::Create(Context, Zero, Context.IntTy, OpLoc);

          Sema::CodeSynthesisContext Ctx;
          Ctx.Kind = Sema::CodeSynthesisContext::RewritingOperatorAsSpaceship;
          Ctx.Entity = FnDecl;
          pushCodeSynthesisContext(Ctx);

          R = CreateOverloadedBinOp(
              OpLoc, Opc, Fns, IsReversed ? ZeroLiteral : R.get(),
              IsReversed ? R.get() : ZeroLiteral, PerformADL,
              /*AllowRewrittenCandidates=*/false);

          popCodeSynthesisContext();
        }
        if (R.isInvalid())
          return ExprError();
      } else {
        assert(ChosenOp == Op && "unexpected operator name")((void)0);
      }

      // Make a note in the AST if we did any rewriting.
      if (Best->RewriteKind != CRK_None)
        R = new (Context) CXXRewrittenBinaryOperator(R.get(), IsReversed);

      return R;
    } else {
      // We matched a built-in operator. Convert the arguments, then
      // break out so that we will build the appropriate built-in
      // operator node.
      ExprResult ArgsRes0 = PerformImplicitConversion(
          Args[0], Best->BuiltinParamTypes[0], Best->Conversions[0],
          AA_Passing, CCK_ForBuiltinOverloadedOp);
      if (ArgsRes0.isInvalid())
        return ExprError();
      Args[0] = ArgsRes0.get();

      ExprResult ArgsRes1 = PerformImplicitConversion(
          Args[1], Best->BuiltinParamTypes[1], Best->Conversions[1],
          AA_Passing, CCK_ForBuiltinOverloadedOp);
      if (ArgsRes1.isInvalid())
        return ExprError();
      Args[1] = ArgsRes1.get();
      break;
    }
  }

  case OR_No_Viable_Function: {
    // C++ [over.match.oper]p9:
    //   If the operator is the operator , [...] and there are no
    //   viable functions, then the operator is assumed to be the
    //   built-in operator and interpreted according to clause 5.
    if (Opc == BO_Comma)
      break;

    // When defaulting an 'operator<=>', we can try to synthesize a three-way
    // compare result using '==' and '<'.
    if (DefaultedFn && Opc == BO_Cmp) {
      ExprResult E = BuildSynthesizedThreeWayComparison(OpLoc, Fns, Args[0],
                                                        Args[1], DefaultedFn);
      if (E.isInvalid() || E.isUsable())
        return E;
    }

    // For class as left operand for assignment or compound assignment
    // operator do not fall through to handling in built-in, but report that
    // no overloaded assignment operator found
    ExprResult Result = ExprError();
    StringRef OpcStr = BinaryOperator::getOpcodeStr(Opc);
    auto Cands = CandidateSet.CompleteCandidates(*this, OCD_AllCandidates,
                                                 Args, OpLoc);
    DeferDiagsRAII DDR(*this,
                       CandidateSet.shouldDeferDiags(*this, Args, OpLoc));
    if (Args[0]->getType()->isRecordType() &&
        Opc >= BO_Assign && Opc <= BO_OrAssign) {
      Diag(OpLoc,  diag::err_ovl_no_viable_oper)
           << BinaryOperator::getOpcodeStr(Opc)
           << Args[0]->getSourceRange() << Args[1]->getSourceRange();
      if (Args[0]->getType()->isIncompleteType()) {
        Diag(OpLoc, diag::note_assign_lhs_incomplete)
          << Args[0]->getType()
          << Args[0]->getSourceRange() << Args[1]->getSourceRange();
      }
    } else {
      // This is an erroneous use of an operator which can be overloaded by
      // a non-member function. Check for non-member operators which were
      // defined too late to be candidates.
      if (DiagnoseTwoPhaseOperatorLookup(*this, Op, OpLoc, Args))
        // FIXME: Recover by calling the found function.
        return ExprError();

      // No viable function; try to create a built-in operation, which will
      // produce an error. Then, show the non-viable candidates.
      Result = CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);
    }
    assert(Result.isInvalid() &&((void)0)
           "C++ binary operator overloading is missing candidates!")((void)0);
    CandidateSet.NoteCandidates(*this, Args, Cands, OpcStr, OpLoc);
    return Result;
  }

  case OR_Ambiguous:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(OpLoc, PDiag(diag::err_ovl_ambiguous_oper_binary)
                                       << BinaryOperator::getOpcodeStr(Opc)
                                       << Args[0]->getType()
                                       << Args[1]->getType()
                                       << Args[0]->getSourceRange()
                                       << Args[1]->getSourceRange()),
        *this, OCD_AmbiguousCandidates, Args, BinaryOperator::getOpcodeStr(Opc),
        OpLoc);
    return ExprError();

  case OR_Deleted:
    if (isImplicitlyDeleted(Best->Function)) {
      FunctionDecl *DeletedFD = Best->Function;
      DefaultedFunctionKind DFK = getDefaultedFunctionKind(DeletedFD);
      if (DFK.isSpecialMember()) {
        Diag(OpLoc, diag::err_ovl_deleted_special_oper)
          << Args[0]->getType() << DFK.asSpecialMember();
      } else {
        assert(DFK.isComparison())((void)0);
        Diag(OpLoc, diag::err_ovl_deleted_comparison)
          << Args[0]->getType() << DeletedFD;
      }

      // The user probably meant to call this special member. Just
      // explain why it's deleted.
      NoteDeletedFunction(DeletedFD);
      return ExprError();
    }
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(
            OpLoc, PDiag(diag::err_ovl_deleted_oper)
                       << getOperatorSpelling(Best->Function->getDeclName()
                                                  .getCXXOverloadedOperator())
                       << Args[0]->getSourceRange()
                       << Args[1]->getSourceRange()),
        *this, OCD_AllCandidates, Args, BinaryOperator::getOpcodeStr(Opc),
        OpLoc);
    return ExprError();
}

// We matched a built-in operator; build it.
return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);
13898}

13900ExprResult Sema::BuildSynthesizedThreeWayComparison(
  SourceLocation OpLoc, const UnresolvedSetImpl &Fns, Expr *LHS, Expr *RHS,
  FunctionDecl *DefaultedFn) {
const ComparisonCategoryInfo *Info =
    Context.CompCategories.lookupInfoForType(DefaultedFn->getReturnType());
// If we're not producing a known comparison category type, we can't
// synthesize a three-way comparison. Let the caller diagnose this.
if (!Info)
  return ExprResult((Expr*)nullptr);

// If we ever want to perform this synthesis more generally, we will need to
// apply the temporary materialization conversion to the operands.
assert(LHS->isGLValue() && RHS->isGLValue() &&((void)0)
       "cannot use prvalue expressions more than once")((void)0);
Expr *OrigLHS = LHS;
Expr *OrigRHS = RHS;

// Replace the LHS and RHS with OpaqueValueExprs; we're going to refer to
// each of them multiple times below.
LHS = new (Context)
    OpaqueValueExpr(LHS->getExprLoc(), LHS->getType(), LHS->getValueKind(),
                    LHS->getObjectKind(), LHS);
RHS = new (Context)
    OpaqueValueExpr(RHS->getExprLoc(), RHS->getType(), RHS->getValueKind(),
                    RHS->getObjectKind(), RHS);

ExprResult Eq = CreateOverloadedBinOp(OpLoc, BO_EQ, Fns, LHS, RHS, true, true,
                                      DefaultedFn);
if (Eq.isInvalid())
  return ExprError();

ExprResult Less = CreateOverloadedBinOp(OpLoc, BO_LT, Fns, LHS, RHS, true,
                                        true, DefaultedFn);
if (Less.isInvalid())
  return ExprError();

ExprResult Greater;
if (Info->isPartial()) {
  Greater = CreateOverloadedBinOp(OpLoc, BO_LT, Fns, RHS, LHS, true, true,
                                  DefaultedFn);
  if (Greater.isInvalid())
    return ExprError();
}

// Form the list of comparisons we're going to perform.
struct Comparison {
  ExprResult Cmp;
  ComparisonCategoryResult Result;
} Comparisons[4] =
{ {Eq, Info->isStrong() ? ComparisonCategoryResult::Equal
                        : ComparisonCategoryResult::Equivalent},
  {Less, ComparisonCategoryResult::Less},
  {Greater, ComparisonCategoryResult::Greater},
  {ExprResult(), ComparisonCategoryResult::Unordered},
};

int I = Info->isPartial() ? 3 : 2;

// Combine the comparisons with suitable conditional expressions.
ExprResult Result;
for (; I >= 0; --I) {
  // Build a reference to the comparison category constant.
  auto *VI = Info->lookupValueInfo(Comparisons[I].Result);
  // FIXME: Missing a constant for a comparison category. Diagnose this?
  if (!VI)
    return ExprResult((Expr*)nullptr);
  ExprResult ThisResult =
      BuildDeclarationNameExpr(CXXScopeSpec(), DeclarationNameInfo(), VI->VD);
  if (ThisResult.isInvalid())
    return ExprError();

  // Build a conditional unless this is the final case.
  if (Result.get()) {
    Result = ActOnConditionalOp(OpLoc, OpLoc, Comparisons[I].Cmp.get(),
                                ThisResult.get(), Result.get());
    if (Result.isInvalid())
      return ExprError();
  } else {
    Result = ThisResult;
  }
}

// Build a PseudoObjectExpr to model the rewriting of an <=> operator, and to
// bind the OpaqueValueExprs before they're (repeatedly) used.
Expr *SyntacticForm = BinaryOperator::Create(
    Context, OrigLHS, OrigRHS, BO_Cmp, Result.get()->getType(),
    Result.get()->getValueKind(), Result.get()->getObjectKind(), OpLoc,
    CurFPFeatureOverrides());
Expr *SemanticForm[] = {LHS, RHS, Result.get()};
return PseudoObjectExpr::Create(Context, SyntacticForm, SemanticForm, 2);
13990}

13992ExprResult
13993Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
                                       SourceLocation RLoc,
                                       Expr *Base, Expr *Idx) {
Expr *Args[2] = { Base, Idx };
DeclarationName OpName =
    Context.DeclarationNames.getCXXOperatorName(OO_Subscript);

// If either side is type-dependent, create an appropriate dependent
// expression.
if (Args[0]->isTypeDependent() || Args[1]->isTypeDependent()) {

  CXXRecordDecl *NamingClass = nullptr; // lookup ignores member operators
  // CHECKME: no 'operator' keyword?
  DeclarationNameInfo OpNameInfo(OpName, LLoc);
  OpNameInfo.setCXXOperatorNameRange(SourceRange(LLoc, RLoc));
  ExprResult Fn = CreateUnresolvedLookupExpr(
      NamingClass, NestedNameSpecifierLoc(), OpNameInfo, UnresolvedSet<0>());
  if (Fn.isInvalid())
    return ExprError();
  // Can't add any actual overloads yet

  return CXXOperatorCallExpr::Create(Context, OO_Subscript, Fn.get(), Args,
                                     Context.DependentTy, VK_PRValue, RLoc,
                                     CurFPFeatureOverrides());
}

// Handle placeholders on both operands.
if (checkPlaceholderForOverload(*this, Args[0]))
  return ExprError();
if (checkPlaceholderForOverload(*this, Args[1]))
  return ExprError();

// Build an empty overload set.
OverloadCandidateSet CandidateSet(LLoc, OverloadCandidateSet::CSK_Operator);

// Subscript can only be overloaded as a member function.

// Add operator candidates that are member functions.
AddMemberOperatorCandidates(OO_Subscript, LLoc, Args, CandidateSet);

// Add builtin operator candidates.
AddBuiltinOperatorCandidates(OO_Subscript, LLoc, Args, CandidateSet);

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, LLoc, Best)) {
  case OR_Success: {
    // We found a built-in operator or an overloaded operator.
    FunctionDecl *FnDecl = Best->Function;

    if (FnDecl) {
      // We matched an overloaded operator. Build a call to that
      // operator.

      CheckMemberOperatorAccess(LLoc, Args[0], Args[1], Best->FoundDecl);

      // Convert the arguments.
      CXXMethodDecl *Method = cast<CXXMethodDecl>(FnDecl);
      ExprResult Arg0 =
        PerformObjectArgumentInitialization(Args[0], /*Qualifier=*/nullptr,
                                            Best->FoundDecl, Method);
      if (Arg0.isInvalid())
        return ExprError();
      Args[0] = Arg0.get();

      // Convert the arguments.
      ExprResult InputInit
        = PerformCopyInitialization(InitializedEntity::InitializeParameter(
                                                    Context,
                                                    FnDecl->getParamDecl(0)),
                                    SourceLocation(),
                                    Args[1]);
      if (InputInit.isInvalid())
        return ExprError();

      Args[1] = InputInit.getAs<Expr>();

      // Build the actual expression node.
      DeclarationNameInfo OpLocInfo(OpName, LLoc);
      OpLocInfo.setCXXOperatorNameRange(SourceRange(LLoc, RLoc));
      ExprResult FnExpr = CreateFunctionRefExpr(*this, FnDecl,
                                                Best->FoundDecl,
                                                Base,
                                                HadMultipleCandidates,
                                                OpLocInfo.getLoc(),
                                                OpLocInfo.getInfo());
      if (FnExpr.isInvalid())
        return ExprError();

      // Determine the result type
      QualType ResultTy = FnDecl->getReturnType();
      ExprValueKind VK = Expr::getValueKindForType(ResultTy);
      ResultTy = ResultTy.getNonLValueExprType(Context);

      CXXOperatorCallExpr *TheCall = CXXOperatorCallExpr::Create(
          Context, OO_Subscript, FnExpr.get(), Args, ResultTy, VK, RLoc,
          CurFPFeatureOverrides());
      if (CheckCallReturnType(FnDecl->getReturnType(), LLoc, TheCall, FnDecl))
        return ExprError();

      if (CheckFunctionCall(Method, TheCall,
                            Method->getType()->castAs<FunctionProtoType>()))
        return ExprError();

      return MaybeBindToTemporary(TheCall);
    } else {
      // We matched a built-in operator. Convert the arguments, then
      // break out so that we will build the appropriate built-in
      // operator node.
      ExprResult ArgsRes0 = PerformImplicitConversion(
          Args[0], Best->BuiltinParamTypes[0], Best->Conversions[0],
          AA_Passing, CCK_ForBuiltinOverloadedOp);
      if (ArgsRes0.isInvalid())
        return ExprError();
      Args[0] = ArgsRes0.get();

      ExprResult ArgsRes1 = PerformImplicitConversion(
          Args[1], Best->BuiltinParamTypes[1], Best->Conversions[1],
          AA_Passing, CCK_ForBuiltinOverloadedOp);
      if (ArgsRes1.isInvalid())
        return ExprError();
      Args[1] = ArgsRes1.get();

      break;
    }
  }

  case OR_No_Viable_Function: {
    PartialDiagnostic PD = CandidateSet.empty()
        ? (PDiag(diag::err_ovl_no_oper)
           << Args[0]->getType() << /*subscript*/ 0
           << Args[0]->getSourceRange() << Args[1]->getSourceRange())
        : (PDiag(diag::err_ovl_no_viable_subscript)
           << Args[0]->getType() << Args[0]->getSourceRange()
           << Args[1]->getSourceRange());
    CandidateSet.NoteCandidates(PartialDiagnosticAt(LLoc, PD), *this,
                                OCD_AllCandidates, Args, "[]", LLoc);
    return ExprError();
  }

  case OR_Ambiguous:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(LLoc, PDiag(diag::err_ovl_ambiguous_oper_binary)
                                      << "[]" << Args[0]->getType()
                                      << Args[1]->getType()
                                      << Args[0]->getSourceRange()
                                      << Args[1]->getSourceRange()),
        *this, OCD_AmbiguousCandidates, Args, "[]", LLoc);
    return ExprError();

  case OR_Deleted:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(LLoc, PDiag(diag::err_ovl_deleted_oper)
                                      << "[]" << Args[0]->getSourceRange()
                                      << Args[1]->getSourceRange()),
        *this, OCD_AllCandidates, Args, "[]", LLoc);
    return ExprError();
  }

// We matched a built-in operator; build it.
return CreateBuiltinArraySubscriptExpr(Args[0], LLoc, Args[1], RLoc);
14156}

14158/// BuildCallToMemberFunction - Build a call to a member
14159/// function. MemExpr is the expression that refers to the member
14160/// function (and includes the object parameter), Args/NumArgs are the
14161/// arguments to the function call (not including the object
14162/// parameter). The caller needs to validate that the member
14163/// expression refers to a non-static member function or an overloaded
14164/// member function.
14165ExprResult Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
                                         SourceLocation LParenLoc,
                                         MultiExprArg Args,
                                         SourceLocation RParenLoc,
                                         bool AllowRecovery) {
assert(MemExprE->getType() == Context.BoundMemberTy ||((void)0)
       MemExprE->getType() == Context.OverloadTy)((void)0);

// Dig out the member expression. This holds both the object
// argument and the member function we're referring to.
Expr *NakedMemExpr = MemExprE->IgnoreParens();

// Determine whether this is a call to a pointer-to-member function.
if (BinaryOperator *op = dyn_cast<BinaryOperator>(NakedMemExpr)) {
  assert(op->getType() == Context.BoundMemberTy)((void)0);
  assert(op->getOpcode() == BO_PtrMemD || op->getOpcode() == BO_PtrMemI)((void)0);

  QualType fnType =
    op->getRHS()->getType()->castAs<MemberPointerType>()->getPointeeType();

  const FunctionProtoType *proto = fnType->castAs<FunctionProtoType>();
  QualType resultType = proto->getCallResultType(Context);
  ExprValueKind valueKind = Expr::getValueKindForType(proto->getReturnType());

  // Check that the object type isn't more qualified than the
  // member function we're calling.
  Qualifiers funcQuals = proto->getMethodQuals();

  QualType objectType = op->getLHS()->getType();
  if (op->getOpcode() == BO_PtrMemI)
    objectType = objectType->castAs<PointerType>()->getPointeeType();
  Qualifiers objectQuals = objectType.getQualifiers();

  Qualifiers difference = objectQuals - funcQuals;
  difference.removeObjCGCAttr();
  difference.removeAddressSpace();
  if (difference) {
    std::string qualsString = difference.getAsString();
    Diag(LParenLoc, diag::err_pointer_to_member_call_drops_quals)
      << fnType.getUnqualifiedType()
      << qualsString
      << (qualsString.find(' ') == std::string::npos ? 1 : 2);
  }

  CXXMemberCallExpr *call = CXXMemberCallExpr::Create(
      Context, MemExprE, Args, resultType, valueKind, RParenLoc,
      CurFPFeatureOverrides(), proto->getNumParams());

  if (CheckCallReturnType(proto->getReturnType(), op->getRHS()->getBeginLoc(),
                          call, nullptr))
    return ExprError();

  if (ConvertArgumentsForCall(call, op, nullptr, proto, Args, RParenLoc))
    return ExprError();

  if (CheckOtherCall(call, proto))
    return ExprError();

  return MaybeBindToTemporary(call);
}

// We only try to build a recovery expr at this level if we can preserve
// the return type, otherwise we return ExprError() and let the caller
// recover.
auto BuildRecoveryExpr = [&](QualType Type) {
  if (!AllowRecovery)
    return ExprError();
  std::vector<Expr *> SubExprs = {MemExprE};
  llvm::for_each(Args, [&SubExprs](Expr *E) { SubExprs.push_back(E); });
  return CreateRecoveryExpr(MemExprE->getBeginLoc(), RParenLoc, SubExprs,
                            Type);
};
if (isa<CXXPseudoDestructorExpr>(NakedMemExpr))
  return CallExpr::Create(Context, MemExprE, Args, Context.VoidTy, VK_PRValue,
                          RParenLoc, CurFPFeatureOverrides());

UnbridgedCastsSet UnbridgedCasts;
if (checkArgPlaceholdersForOverload(*this, Args, UnbridgedCasts))
  return ExprError();

MemberExpr *MemExpr;
CXXMethodDecl *Method = nullptr;
DeclAccessPair FoundDecl = DeclAccessPair::make(nullptr, AS_public);
NestedNameSpecifier *Qualifier = nullptr;
if (isa<MemberExpr>(NakedMemExpr)) {
  MemExpr = cast<MemberExpr>(NakedMemExpr);
  Method = cast<CXXMethodDecl>(MemExpr->getMemberDecl());
  FoundDecl = MemExpr->getFoundDecl();
  Qualifier = MemExpr->getQualifier();
  UnbridgedCasts.restore();
} else {
  UnresolvedMemberExpr *UnresExpr = cast<UnresolvedMemberExpr>(NakedMemExpr);
  Qualifier = UnresExpr->getQualifier();

  QualType ObjectType = UnresExpr->getBaseType();
  Expr::Classification ObjectClassification
    = UnresExpr->isArrow()? Expr::Classification::makeSimpleLValue()
                          : UnresExpr->getBase()->Classify(Context);

  // Add overload candidates
  OverloadCandidateSet CandidateSet(UnresExpr->getMemberLoc(),
                                    OverloadCandidateSet::CSK_Normal);

  // FIXME: avoid copy.
  TemplateArgumentListInfo TemplateArgsBuffer, *TemplateArgs = nullptr;
  if (UnresExpr->hasExplicitTemplateArgs()) {
    UnresExpr->copyTemplateArgumentsInto(TemplateArgsBuffer);
    TemplateArgs = &TemplateArgsBuffer;
  }

  for (UnresolvedMemberExpr::decls_iterator I = UnresExpr->decls_begin(),
         E = UnresExpr->decls_end(); I != E; ++I) {

    NamedDecl *Func = *I;
    CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(Func->getDeclContext());
    if (isa<UsingShadowDecl>(Func))
      Func = cast<UsingShadowDecl>(Func)->getTargetDecl();


    // Microsoft supports direct constructor calls.
    if (getLangOpts().MicrosoftExt && isa<CXXConstructorDecl>(Func)) {
      AddOverloadCandidate(cast<CXXConstructorDecl>(Func), I.getPair(), Args,
                           CandidateSet,
                           /*SuppressUserConversions*/ false);
    } else if ((Method = dyn_cast<CXXMethodDecl>(Func))) {
      // If explicit template arguments were provided, we can't call a
      // non-template member function.
      if (TemplateArgs)
        continue;

      AddMethodCandidate(Method, I.getPair(), ActingDC, ObjectType,
                         ObjectClassification, Args, CandidateSet,
                         /*SuppressUserConversions=*/false);
    } else {
      AddMethodTemplateCandidate(
          cast<FunctionTemplateDecl>(Func), I.getPair(), ActingDC,
          TemplateArgs, ObjectType, ObjectClassification, Args, CandidateSet,
          /*SuppressUserConversions=*/false);
    }
  }

  DeclarationName DeclName = UnresExpr->getMemberName();

  UnbridgedCasts.restore();

  OverloadCandidateSet::iterator Best;
  bool Succeeded = false;
  switch (CandidateSet.BestViableFunction(*this, UnresExpr->getBeginLoc(),
                                          Best)) {
  case OR_Success:
    Method = cast<CXXMethodDecl>(Best->Function);
    FoundDecl = Best->FoundDecl;
    CheckUnresolvedMemberAccess(UnresExpr, Best->FoundDecl);
    if (DiagnoseUseOfDecl(Best->FoundDecl, UnresExpr->getNameLoc()))
      break;
    // If FoundDecl is different from Method (such as if one is a template
    // and the other a specialization), make sure DiagnoseUseOfDecl is
    // called on both.
    // FIXME: This would be more comprehensively addressed by modifying
    // DiagnoseUseOfDecl to accept both the FoundDecl and the decl
    // being used.
    if (Method != FoundDecl.getDecl() &&
                    DiagnoseUseOfDecl(Method, UnresExpr->getNameLoc()))
      break;
    Succeeded = true;
    break;

  case OR_No_Viable_Function:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(
            UnresExpr->getMemberLoc(),
            PDiag(diag::err_ovl_no_viable_member_function_in_call)
                << DeclName << MemExprE->getSourceRange()),
        *this, OCD_AllCandidates, Args);
    break;
  case OR_Ambiguous:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(UnresExpr->getMemberLoc(),
                            PDiag(diag::err_ovl_ambiguous_member_call)
                                << DeclName << MemExprE->getSourceRange()),
        *this, OCD_AmbiguousCandidates, Args);
    break;
  case OR_Deleted:
    CandidateSet.NoteCandidates(
        PartialDiagnosticAt(UnresExpr->getMemberLoc(),
                            PDiag(diag::err_ovl_deleted_member_call)
                                << DeclName << MemExprE->getSourceRange()),
        *this, OCD_AllCandidates, Args);
    break;
  }
  // Overload resolution fails, try to recover.
  if (!Succeeded)
    return BuildRecoveryExpr(chooseRecoveryType(CandidateSet, &Best));

  MemExprE = FixOverloadedFunctionReference(MemExprE, FoundDecl, Method);

  // If overload resolution picked a static member, build a
  // non-member call based on that function.
  if (Method->isStatic()) {
    return BuildResolvedCallExpr(MemExprE, Method, LParenLoc, Args,
                                 RParenLoc);
  }

  MemExpr = cast<MemberExpr>(MemExprE->IgnoreParens());
}

QualType ResultType = Method->getReturnType();
ExprValueKind VK = Expr::getValueKindForType(ResultType);
ResultType = ResultType.getNonLValueExprType(Context);

assert(Method && "Member call to something that isn't a method?")((void)0);
const auto *Proto = Method->getType()->castAs<FunctionProtoType>();
CXXMemberCallExpr *TheCall = CXXMemberCallExpr::Create(
    Context, MemExprE, Args, ResultType, VK, RParenLoc,
    CurFPFeatureOverrides(), Proto->getNumParams());

// Check for a valid return type.
if (CheckCallReturnType(Method->getReturnType(), MemExpr->getMemberLoc(),
                        TheCall, Method))
  return BuildRecoveryExpr(ResultType);

// Convert the object argument (for a non-static member function call).
// We only need to do this if there was actually an overload; otherwise
// it was done at lookup.
if (!Method->isStatic()) {
  ExprResult ObjectArg =
    PerformObjectArgumentInitialization(MemExpr->getBase(), Qualifier,
                                        FoundDecl, Method);
  if (ObjectArg.isInvalid())
    return ExprError();
  MemExpr->setBase(ObjectArg.get());
}

// Convert the rest of the arguments
if (ConvertArgumentsForCall(TheCall, MemExpr, Method, Proto, Args,
                            RParenLoc))
  return BuildRecoveryExpr(ResultType);

DiagnoseSentinelCalls(Method, LParenLoc, Args);

if (CheckFunctionCall(Method, TheCall, Proto))
  return ExprError();

// In the case the method to call was not selected by the overloading
// resolution process, we still need to handle the enable_if attribute. Do
// that here, so it will not hide previous -- and more relevant -- errors.
if (auto *MemE = dyn_cast<MemberExpr>(NakedMemExpr)) {
  if (const EnableIfAttr *Attr =
          CheckEnableIf(Method, LParenLoc, Args, true)) {
    Diag(MemE->getMemberLoc(),
         diag::err_ovl_no_viable_member_function_in_call)
        << Method << Method->getSourceRange();
    Diag(Method->getLocation(),
         diag::note_ovl_candidate_disabled_by_function_cond_attr)
        << Attr->getCond()->getSourceRange() << Attr->getMessage();
    return ExprError();
  }
}

if ((isa<CXXConstructorDecl>(CurContext) ||
     isa<CXXDestructorDecl>(CurContext)) &&
    TheCall->getMethodDecl()->isPure()) {
  const CXXMethodDecl *MD = TheCall->getMethodDecl();

  if (isa<CXXThisExpr>(MemExpr->getBase()->IgnoreParenCasts()) &&
      MemExpr->performsVirtualDispatch(getLangOpts())) {
    Diag(MemExpr->getBeginLoc(),
         diag::warn_call_to_pure_virtual_member_function_from_ctor_dtor)
        << MD->getDeclName() << isa<CXXDestructorDecl>(CurContext)
        << MD->getParent();

    Diag(MD->getBeginLoc(), diag::note_previous_decl) << MD->getDeclName();
    if (getLangOpts().AppleKext)
      Diag(MemExpr->getBeginLoc(), diag::note_pure_qualified_call_kext)
          << MD->getParent() << MD->getDeclName();
  }
}

if (CXXDestructorDecl *DD =
        dyn_cast<CXXDestructorDecl>(TheCall->getMethodDecl())) {
  // a->A::f() doesn't go through the vtable, except in AppleKext mode.
  bool CallCanBeVirtual = !MemExpr->hasQualifier() || getLangOpts().AppleKext;
  CheckVirtualDtorCall(DD, MemExpr->getBeginLoc(), /*IsDelete=*/false,
                       CallCanBeVirtual, /*WarnOnNonAbstractTypes=*/true,
                       MemExpr->getMemberLoc());
}

return CheckForImmediateInvocation(MaybeBindToTemporary(TheCall),
                                   TheCall->getMethodDecl());
14454}

14456/// BuildCallToObjectOfClassType - Build a call to an object of class
14457/// type (C++ [over.call.object]), which can end up invoking an
14458/// overloaded function call operator (@c operator()) or performing a
14459/// user-defined conversion on the object argument.
14460ExprResult
14461Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
                                 SourceLocation LParenLoc,
                                 MultiExprArg Args,
                                 SourceLocation RParenLoc) {
if (checkPlaceholderForOverload(*this, Obj))
  return ExprError();
ExprResult Object = Obj;

UnbridgedCastsSet UnbridgedCasts;
if (checkArgPlaceholdersForOverload(*this, Args, UnbridgedCasts))
  return ExprError();

assert(Object.get()->getType()->isRecordType() &&((void)0)
       "Requires object type argument")((void)0);

// C++ [over.call.object]p1:
//  If the primary-expression E in the function call syntax
//  evaluates to a class object of type "cv T", then the set of
//  candidate functions includes at least the function call
//  operators of T. The function call operators of T are obtained by
//  ordinary lookup of the name operator() in the context of
//  (E).operator().
OverloadCandidateSet CandidateSet(LParenLoc,
                                  OverloadCandidateSet::CSK_Operator);
DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(OO_Call);

if (RequireCompleteType(LParenLoc, Object.get()->getType(),
                        diag::err_incomplete_object_call, Object.get()))
  return true;

const auto *Record = Object.get()->getType()->castAs<RecordType>();
LookupResult R(*this, OpName, LParenLoc, LookupOrdinaryName);
LookupQualifiedName(R, Record->getDecl());
R.suppressDiagnostics();

for (LookupResult::iterator Oper = R.begin(), OperEnd = R.end();
     Oper != OperEnd; ++Oper) {
  AddMethodCandidate(Oper.getPair(), Object.get()->getType(),
                     Object.get()->Classify(Context), Args, CandidateSet,
                     /*SuppressUserConversion=*/false);
}

// C++ [over.call.object]p2:
//   In addition, for each (non-explicit in C++0x) conversion function
//   declared in T of the form
//
//        operator conversion-type-id () cv-qualifier;
//
//   where cv-qualifier is the same cv-qualification as, or a
//   greater cv-qualification than, cv, and where conversion-type-id
//   denotes the type "pointer to function of (P1,...,Pn) returning
//   R", or the type "reference to pointer to function of
//   (P1,...,Pn) returning R", or the type "reference to function
//   of (P1,...,Pn) returning R", a surrogate call function [...]
//   is also considered as a candidate function. Similarly,
//   surrogate call functions are added to the set of candidate
//   functions for each conversion function declared in an
//   accessible base class provided the function is not hidden
//   within T by another intervening declaration.
const auto &Conversions =
    cast<CXXRecordDecl>(Record->getDecl())->getVisibleConversionFunctions();
for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
  NamedDecl *D = *I;
  CXXRecordDecl *ActingContext = cast<CXXRecordDecl>(D->getDeclContext());
  if (isa<UsingShadowDecl>(D))
    D = cast<UsingShadowDecl>(D)->getTargetDecl();

  // Skip over templated conversion functions; they aren't
  // surrogates.
  if (isa<FunctionTemplateDecl>(D))
    continue;

  CXXConversionDecl *Conv = cast<CXXConversionDecl>(D);
  if (!Conv->isExplicit()) {
    // Strip the reference type (if any) and then the pointer type (if
    // any) to get down to what might be a function type.
    QualType ConvType = Conv->getConversionType().getNonReferenceType();
    if (const PointerType *ConvPtrType = ConvType->getAs<PointerType>())
      ConvType = ConvPtrType->getPointeeType();

    if (const FunctionProtoType *Proto = ConvType->getAs<FunctionProtoType>())
    {
      AddSurrogateCandidate(Conv, I.getPair(), ActingContext, Proto,
                            Object.get(), Args, CandidateSet);
    }
  }
}

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, Object.get()->getBeginLoc(),
                                        Best)) {
case OR_Success:
  // Overload resolution succeeded; we'll build the appropriate call
  // below.
  break;

case OR_No_Viable_Function: {
  PartialDiagnostic PD =
      CandidateSet.empty()
          ? (PDiag(diag::err_ovl_no_oper)
             << Object.get()->getType() << /*call*/ 1
             << Object.get()->getSourceRange())
          : (PDiag(diag::err_ovl_no_viable_object_call)
             << Object.get()->getType() << Object.get()->getSourceRange());
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(Object.get()->getBeginLoc(), PD), *this,
      OCD_AllCandidates, Args);
  break;
}
case OR_Ambiguous:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(Object.get()->getBeginLoc(),
                          PDiag(diag::err_ovl_ambiguous_object_call)
                              << Object.get()->getType()
                              << Object.get()->getSourceRange()),
      *this, OCD_AmbiguousCandidates, Args);
  break;

case OR_Deleted:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(Object.get()->getBeginLoc(),
                          PDiag(diag::err_ovl_deleted_object_call)
                              << Object.get()->getType()
                              << Object.get()->getSourceRange()),
      *this, OCD_AllCandidates, Args);
  break;
}

if (Best == CandidateSet.end())
  return true;

UnbridgedCasts.restore();

if (Best->Function == nullptr) {
  // Since there is no function declaration, this is one of the
  // surrogate candidates. Dig out the conversion function.
  CXXConversionDecl *Conv
    = cast<CXXConversionDecl>(
                       Best->Conversions[0].UserDefined.ConversionFunction);

  CheckMemberOperatorAccess(LParenLoc, Object.get(), nullptr,
                            Best->FoundDecl);
  if (DiagnoseUseOfDecl(Best->FoundDecl, LParenLoc))
    return ExprError();
  assert(Conv == Best->FoundDecl.getDecl() &&((void)0)
           "Found Decl & conversion-to-functionptr should be same, right?!")((void)0);
  // We selected one of the surrogate functions that converts the
  // object parameter to a function pointer. Perform the conversion
  // on the object argument, then let BuildCallExpr finish the job.

  // Create an implicit member expr to refer to the conversion operator.
  // and then call it.
  ExprResult Call = BuildCXXMemberCallExpr(Object.get(), Best->FoundDecl,
                                           Conv, HadMultipleCandidates);
  if (Call.isInvalid())
    return ExprError();
  // Record usage of conversion in an implicit cast.
  Call = ImplicitCastExpr::Create(
      Context, Call.get()->getType(), CK_UserDefinedConversion, Call.get(),
      nullptr, VK_PRValue, CurFPFeatureOverrides());

  return BuildCallExpr(S, Call.get(), LParenLoc, Args, RParenLoc);
}

CheckMemberOperatorAccess(LParenLoc, Object.get(), nullptr, Best->FoundDecl);

// We found an overloaded operator(). Build a CXXOperatorCallExpr
// that calls this method, using Object for the implicit object
// parameter and passing along the remaining arguments.
CXXMethodDecl *Method = cast<CXXMethodDecl>(Best->Function);

// An error diagnostic has already been printed when parsing the declaration.
if (Method->isInvalidDecl())
  return ExprError();

const auto *Proto = Method->getType()->castAs<FunctionProtoType>();
unsigned NumParams = Proto->getNumParams();

DeclarationNameInfo OpLocInfo(
             Context.DeclarationNames.getCXXOperatorName(OO_Call), LParenLoc);
OpLocInfo.setCXXOperatorNameRange(SourceRange(LParenLoc, RParenLoc));
ExprResult NewFn = CreateFunctionRefExpr(*this, Method, Best->FoundDecl,
                                         Obj, HadMultipleCandidates,
                                         OpLocInfo.getLoc(),
                                         OpLocInfo.getInfo());
if (NewFn.isInvalid())
  return true;

// The number of argument slots to allocate in the call. If we have default
// arguments we need to allocate space for them as well. We additionally
// need one more slot for the object parameter.
unsigned NumArgsSlots = 1 + std::max<unsigned>(Args.size(), NumParams);

// Build the full argument list for the method call (the implicit object
// parameter is placed at the beginning of the list).
SmallVector<Expr *, 8> MethodArgs(NumArgsSlots);

bool IsError = false;

// Initialize the implicit object parameter.
ExprResult ObjRes =
  PerformObjectArgumentInitialization(Object.get(), /*Qualifier=*/nullptr,
                                      Best->FoundDecl, Method);
if (ObjRes.isInvalid())
  IsError = true;
else
  Object = ObjRes;
MethodArgs[0] = Object.get();

// Check the argument types.
for (unsigned i = 0; i != NumParams; i++) {
  Expr *Arg;
  if (i < Args.size()) {
    Arg = Args[i];

    // Pass the argument.

    ExprResult InputInit
      = PerformCopyInitialization(InitializedEntity::InitializeParameter(
                                                  Context,
                                                  Method->getParamDecl(i)),
                                  SourceLocation(), Arg);

    IsError |= InputInit.isInvalid();
    Arg = InputInit.getAs<Expr>();
  } else {
    ExprResult DefArg
      = BuildCXXDefaultArgExpr(LParenLoc, Method, Method->getParamDecl(i));
    if (DefArg.isInvalid()) {
      IsError = true;
      break;
    }

    Arg = DefArg.getAs<Expr>();
  }

  MethodArgs[i + 1] = Arg;
}

// If this is a variadic call, handle args passed through "...".
if (Proto->isVariadic()) {
  // Promote the arguments (C99 6.5.2.2p7).
  for (unsigned i = NumParams, e = Args.size(); i < e; i++) {
    ExprResult Arg = DefaultVariadicArgumentPromotion(Args[i], VariadicMethod,
                                                      nullptr);
    IsError |= Arg.isInvalid();
    MethodArgs[i + 1] = Arg.get();
  }
}

if (IsError)
  return true;

DiagnoseSentinelCalls(Method, LParenLoc, Args);

// Once we've built TheCall, all of the expressions are properly owned.
QualType ResultTy = Method->getReturnType();
ExprValueKind VK = Expr::getValueKindForType(ResultTy);
ResultTy = ResultTy.getNonLValueExprType(Context);

CXXOperatorCallExpr *TheCall = CXXOperatorCallExpr::Create(
    Context, OO_Call, NewFn.get(), MethodArgs, ResultTy, VK, RParenLoc,
    CurFPFeatureOverrides());

if (CheckCallReturnType(Method->getReturnType(), LParenLoc, TheCall, Method))
  return true;

if (CheckFunctionCall(Method, TheCall, Proto))
  return true;

return CheckForImmediateInvocation(MaybeBindToTemporary(TheCall), Method);
14735}

14737/// BuildOverloadedArrowExpr - Build a call to an overloaded @c operator->
14738///  (if one exists), where @c Base is an expression of class type and
14739/// @c Member is the name of the member we're trying to find.
14740ExprResult
14741Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
                             bool *NoArrowOperatorFound) {
assert(Base->getType()->isRecordType() &&((void)0)
       "left-hand side must have class type")((void)0);

if (checkPlaceholderForOverload(*this, Base))
  return ExprError();

SourceLocation Loc = Base->getExprLoc();

// C++ [over.ref]p1:
//
//   [...] An expression x->m is interpreted as (x.operator->())->m
//   for a class object x of type T if T::operator->() exists and if
//   the operator is selected as the best match function by the
//   overload resolution mechanism (13.3).
DeclarationName OpName =
  Context.DeclarationNames.getCXXOperatorName(OO_Arrow);
OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Operator);

if (RequireCompleteType(Loc, Base->getType(),
                        diag::err_typecheck_incomplete_tag, Base))
  return ExprError();

LookupResult R(*this, OpName, OpLoc, LookupOrdinaryName);
LookupQualifiedName(R, Base->getType()->castAs<RecordType>()->getDecl());
R.suppressDiagnostics();

for (LookupResult::iterator Oper = R.begin(), OperEnd = R.end();
     Oper != OperEnd; ++Oper) {
  AddMethodCandidate(Oper.getPair(), Base->getType(), Base->Classify(Context),
                     None, CandidateSet, /*SuppressUserConversion=*/false);
}

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, OpLoc, Best)) {
case OR_Success:
  // Overload resolution succeeded; we'll build the call below.
  break;

case OR_No_Viable_Function: {
  auto Cands = CandidateSet.CompleteCandidates(*this, OCD_AllCandidates, Base);
  if (CandidateSet.empty()) {
    QualType BaseType = Base->getType();
    if (NoArrowOperatorFound) {
      // Report this specific error to the caller instead of emitting a
      // diagnostic, as requested.
      *NoArrowOperatorFound = true;
      return ExprError();
    }
    Diag(OpLoc, diag::err_typecheck_member_reference_arrow)
      << BaseType << Base->getSourceRange();
    if (BaseType->isRecordType() && !BaseType->isPointerType()) {
      Diag(OpLoc, diag::note_typecheck_member_reference_suggestion)
        << FixItHint::CreateReplacement(OpLoc, ".");
    }
  } else
    Diag(OpLoc, diag::err_ovl_no_viable_oper)
      << "operator->" << Base->getSourceRange();
  CandidateSet.NoteCandidates(*this, Base, Cands);
  return ExprError();
}
case OR_Ambiguous:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(OpLoc, PDiag(diag::err_ovl_ambiguous_oper_unary)
                                     << "->" << Base->getType()
                                     << Base->getSourceRange()),
      *this, OCD_AmbiguousCandidates, Base);
  return ExprError();

case OR_Deleted:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(OpLoc, PDiag(diag::err_ovl_deleted_oper)
                                     << "->" << Base->getSourceRange()),
      *this, OCD_AllCandidates, Base);
  return ExprError();
}

CheckMemberOperatorAccess(OpLoc, Base, nullptr, Best->FoundDecl);

// Convert the object parameter.
CXXMethodDecl *Method = cast<CXXMethodDecl>(Best->Function);
ExprResult BaseResult =
  PerformObjectArgumentInitialization(Base, /*Qualifier=*/nullptr,
                                      Best->FoundDecl, Method);
if (BaseResult.isInvalid())
  return ExprError();
Base = BaseResult.get();

// Build the operator call.
ExprResult FnExpr = CreateFunctionRefExpr(*this, Method, Best->FoundDecl,
                                          Base, HadMultipleCandidates, OpLoc);
if (FnExpr.isInvalid())
  return ExprError();

QualType ResultTy = Method->getReturnType();
ExprValueKind VK = Expr::getValueKindForType(ResultTy);
ResultTy = ResultTy.getNonLValueExprType(Context);
CXXOperatorCallExpr *TheCall =
    CXXOperatorCallExpr::Create(Context, OO_Arrow, FnExpr.get(), Base,
                                ResultTy, VK, OpLoc, CurFPFeatureOverrides());

if (CheckCallReturnType(Method->getReturnType(), OpLoc, TheCall, Method))
  return ExprError();

if (CheckFunctionCall(Method, TheCall,
                      Method->getType()->castAs<FunctionProtoType>()))
  return ExprError();

return MaybeBindToTemporary(TheCall);
14854}

14856/// BuildLiteralOperatorCall - Build a UserDefinedLiteral by creating a call to
14857/// a literal operator described by the provided lookup results.
14858ExprResult Sema::BuildLiteralOperatorCall(LookupResult &R,
                                        DeclarationNameInfo &SuffixInfo,
                                        ArrayRef<Expr*> Args,
                                        SourceLocation LitEndLoc,
                                     TemplateArgumentListInfo *TemplateArgs) {
SourceLocation UDSuffixLoc = SuffixInfo.getCXXLiteralOperatorNameLoc();

OverloadCandidateSet CandidateSet(UDSuffixLoc,
                                  OverloadCandidateSet::CSK_Normal);
AddNonMemberOperatorCandidates(R.asUnresolvedSet(), Args, CandidateSet,
                               TemplateArgs);

bool HadMultipleCandidates = (CandidateSet.size() > 1);

// Perform overload resolution. This will usually be trivial, but might need
// to perform substitutions for a literal operator template.
OverloadCandidateSet::iterator Best;
switch (CandidateSet.BestViableFunction(*this, UDSuffixLoc, Best)) {
case OR_Success:
case OR_Deleted:
  break;

case OR_No_Viable_Function:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(UDSuffixLoc,
                          PDiag(diag::err_ovl_no_viable_function_in_call)
                              << R.getLookupName()),
      *this, OCD_AllCandidates, Args);
  return ExprError();

case OR_Ambiguous:
  CandidateSet.NoteCandidates(
      PartialDiagnosticAt(R.getNameLoc(), PDiag(diag::err_ovl_ambiguous_call)
                                              << R.getLookupName()),
      *this, OCD_AmbiguousCandidates, Args);
  return ExprError();
}

FunctionDecl *FD = Best->Function;
ExprResult Fn = CreateFunctionRefExpr(*this, FD, Best->FoundDecl,
                                      nullptr, HadMultipleCandidates,
                                      SuffixInfo.getLoc(),
                                      SuffixInfo.getInfo());
if (Fn.isInvalid())
  return true;

// Check the argument types. This should almost always be a no-op, except
// that array-to-pointer decay is applied to string literals.
Expr *ConvArgs[2];
for (unsigned ArgIdx = 0, N = Args.size(); ArgIdx != N; ++ArgIdx) {
  ExprResult InputInit = PerformCopyInitialization(
    InitializedEntity::InitializeParameter(Context, FD->getParamDecl(ArgIdx)),
    SourceLocation(), Args[ArgIdx]);
  if (InputInit.isInvalid())
    return true;
  ConvArgs[ArgIdx] = InputInit.get();
}

QualType ResultTy = FD->getReturnType();
ExprValueKind VK = Expr::getValueKindForType(ResultTy);
ResultTy = ResultTy.getNonLValueExprType(Context);

UserDefinedLiteral *UDL = UserDefinedLiteral::Create(
    Context, Fn.get(), llvm::makeArrayRef(ConvArgs, Args.size()), ResultTy,
    VK, LitEndLoc, UDSuffixLoc, CurFPFeatureOverrides());

if (CheckCallReturnType(FD->getReturnType(), UDSuffixLoc, UDL, FD))
  return ExprError();

if (CheckFunctionCall(FD, UDL, nullptr))
  return ExprError();

return CheckForImmediateInvocation(MaybeBindToTemporary(UDL), FD);
14931}

14933/// Build a call to 'begin' or 'end' for a C++11 for-range statement. If the
14934/// given LookupResult is non-empty, it is assumed to describe a member which
14935/// will be invoked. Otherwise, the function will be found via argument
14936/// dependent lookup.
14937/// CallExpr is set to a valid expression and FRS_Success returned on success,
14938/// otherwise CallExpr is set to ExprError() and some non-success value
14939/// is returned.
14940Sema::ForRangeStatus
14941Sema::BuildForRangeBeginEndCall(SourceLocation Loc,
                              SourceLocation RangeLoc,
                              const DeclarationNameInfo &NameInfo,
                              LookupResult &MemberLookup,
                              OverloadCandidateSet *CandidateSet,
                              Expr *Range, ExprResult *CallExpr) {
Scope *S = nullptr;

CandidateSet->clear(OverloadCandidateSet::CSK_Normal);
if (!MemberLookup.empty()) {
  ExprResult MemberRef =
      BuildMemberReferenceExpr(Range, Range->getType(), Loc,
                               /*IsPtr=*/false, CXXScopeSpec(),
                               /*TemplateKWLoc=*/SourceLocation(),
                               /*FirstQualifierInScope=*/nullptr,
                               MemberLookup,
                               /*TemplateArgs=*/nullptr, S);
  if (MemberRef.isInvalid()) {
    *CallExpr = ExprError();
    return FRS_DiagnosticIssued;
  }
  *CallExpr = BuildCallExpr(S, MemberRef.get(), Loc, None, Loc, nullptr);
  if (CallExpr->isInvalid()) {
    *CallExpr = ExprError();
    return FRS_DiagnosticIssued;
  }
} else {
  ExprResult FnR = CreateUnresolvedLookupExpr(/*NamingClass=*/nullptr,
                                              NestedNameSpecifierLoc(),
                                              NameInfo, UnresolvedSet<0>());
  if (FnR.isInvalid())
    return FRS_DiagnosticIssued;
  UnresolvedLookupExpr *Fn = cast<UnresolvedLookupExpr>(FnR.get());

  bool CandidateSetError = buildOverloadedCallSet(S, Fn, Fn, Range, Loc,
                                                  CandidateSet, CallExpr);
  if (CandidateSet->empty() || CandidateSetError) {
    *CallExpr = ExprError();
    return FRS_NoViableFunction;
  }
  OverloadCandidateSet::iterator Best;
  OverloadingResult OverloadResult =
      CandidateSet->BestViableFunction(*this, Fn->getBeginLoc(), Best);

  if (OverloadResult == OR_No_Viable_Function) {
    *CallExpr = ExprError();
    return FRS_NoViableFunction;
  }
  *CallExpr = FinishOverloadedCallExpr(*this, S, Fn, Fn, Loc, Range,
                                       Loc, nullptr, CandidateSet, &Best,
                                       OverloadResult,
                                       /*AllowTypoCorrection=*/false);
  if (CallExpr->isInvalid() || OverloadResult != OR_Success) {
    *CallExpr = ExprError();
    return FRS_DiagnosticIssued;
  }
}
return FRS_Success;
14999}


15002/// FixOverloadedFunctionReference - E is an expression that refers to
15003/// a C++ overloaded function (possibly with some parentheses and
15004/// perhaps a '&' around it). We have resolved the overloaded function
15005/// to the function declaration Fn, so patch up the expression E to
15006/// refer (possibly indirectly) to Fn. Returns the new expr.
15007Expr *Sema::FixOverloadedFunctionReference(Expr *E, DeclAccessPair Found,
                                         FunctionDecl *Fn) {
if (ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
  Expr *SubExpr = FixOverloadedFunctionReference(PE->getSubExpr(),
                                                 Found, Fn);
  if (SubExpr == PE->getSubExpr())
    return PE;

  return new (Context) ParenExpr(PE->getLParen(), PE->getRParen(), SubExpr);
}

if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
  Expr *SubExpr = FixOverloadedFunctionReference(ICE->getSubExpr(),
                                                 Found, Fn);
  assert(Context.hasSameType(ICE->getSubExpr()->getType(),((void)0)
                             SubExpr->getType()) &&((void)0)
         "Implicit cast type cannot be determined from overload")((void)0);
  assert(ICE->path_empty() && "fixing up hierarchy conversion?")((void)0);
  if (SubExpr == ICE->getSubExpr())
    return ICE;

  return ImplicitCastExpr::Create(Context, ICE->getType(), ICE->getCastKind(),
                                  SubExpr, nullptr, ICE->getValueKind(),
                                  CurFPFeatureOverrides());
}

if (auto *GSE = dyn_cast<GenericSelectionExpr>(E)) {
  if (!GSE->isResultDependent()) {
    Expr *SubExpr =
        FixOverloadedFunctionReference(GSE->getResultExpr(), Found, Fn);
    if (SubExpr == GSE->getResultExpr())
      return GSE;

    // Replace the resulting type information before rebuilding the generic
    // selection expression.
    ArrayRef<Expr *> A = GSE->getAssocExprs();
    SmallVector<Expr *, 4> AssocExprs(A.begin(), A.end());
    unsigned ResultIdx = GSE->getResultIndex();
    AssocExprs[ResultIdx] = SubExpr;

    return GenericSelectionExpr::Create(
        Context, GSE->getGenericLoc(), GSE->getControllingExpr(),
        GSE->getAssocTypeSourceInfos(), AssocExprs, GSE->getDefaultLoc(),
        GSE->getRParenLoc(), GSE->containsUnexpandedParameterPack(),
        ResultIdx);
  }
  // Rather than fall through to the unreachable, return the original generic
  // selection expression.
  return GSE;
}

if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(E)) {
  assert(UnOp->getOpcode() == UO_AddrOf &&((void)0)
         "Can only take the address of an overloaded function")((void)0);
  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn)) {
    if (Method->isStatic()) {
      // Do nothing: static member functions aren't any different
      // from non-member functions.
    } else {
      // Fix the subexpression, which really has to be an
      // UnresolvedLookupExpr holding an overloaded member function
      // or template.
      Expr *SubExpr = FixOverloadedFunctionReference(UnOp->getSubExpr(),
                                                     Found, Fn);
      if (SubExpr == UnOp->getSubExpr())
        return UnOp;

      assert(isa<DeclRefExpr>(SubExpr)((void)0)
             && "fixed to something other than a decl ref")((void)0);
      assert(cast<DeclRefExpr>(SubExpr)->getQualifier()((void)0)
             && "fixed to a member ref with no nested name qualifier")((void)0);

      // We have taken the address of a pointer to member
      // function. Perform the computation here so that we get the
      // appropriate pointer to member type.
      QualType ClassType
        = Context.getTypeDeclType(cast<RecordDecl>(Method->getDeclContext()));
      QualType MemPtrType
        = Context.getMemberPointerType(Fn->getType(), ClassType.getTypePtr());
      // Under the MS ABI, lock down the inheritance model now.
      if (Context.getTargetInfo().getCXXABI().isMicrosoft())
        (void)isCompleteType(UnOp->getOperatorLoc(), MemPtrType);

      return UnaryOperator::Create(
          Context, SubExpr, UO_AddrOf, MemPtrType, VK_PRValue, OK_Ordinary,
          UnOp->getOperatorLoc(), false, CurFPFeatureOverrides());
    }
  }
  Expr *SubExpr = FixOverloadedFunctionReference(UnOp->getSubExpr(),
                                                 Found, Fn);
  if (SubExpr == UnOp->getSubExpr())
    return UnOp;

  return UnaryOperator::Create(
      Context, SubExpr, UO_AddrOf, Context.getPointerType(SubExpr->getType()),
      VK_PRValue, OK_Ordinary, UnOp->getOperatorLoc(), false,
      CurFPFeatureOverrides());
}

if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(E)) {
  // FIXME: avoid copy.
  TemplateArgumentListInfo TemplateArgsBuffer, *TemplateArgs = nullptr;
  if (ULE->hasExplicitTemplateArgs()) {
    ULE->copyTemplateArgumentsInto(TemplateArgsBuffer);
    TemplateArgs = &TemplateArgsBuffer;
  }

  DeclRefExpr *DRE =
      BuildDeclRefExpr(Fn, Fn->getType(), VK_LValue, ULE->getNameInfo(),
                       ULE->getQualifierLoc(), Found.getDecl(),
                       ULE->getTemplateKeywordLoc(), TemplateArgs);
  DRE->setHadMultipleCandidates(ULE->getNumDecls() > 1);
  return DRE;
}

if (UnresolvedMemberExpr *MemExpr = dyn_cast<UnresolvedMemberExpr>(E)) {
  // FIXME: avoid copy.
  TemplateArgumentListInfo TemplateArgsBuffer, *TemplateArgs = nullptr;
  if (MemExpr->hasExplicitTemplateArgs()) {
    MemExpr->copyTemplateArgumentsInto(TemplateArgsBuffer);
    TemplateArgs = &TemplateArgsBuffer;
  }

  Expr *Base;

  // If we're filling in a static method where we used to have an
  // implicit member access, rewrite to a simple decl ref.
  if (MemExpr->isImplicitAccess()) {
    if (cast<CXXMethodDecl>(Fn)->isStatic()) {
      DeclRefExpr *DRE = BuildDeclRefExpr(
          Fn, Fn->getType(), VK_LValue, MemExpr->getNameInfo(),
          MemExpr->getQualifierLoc(), Found.getDecl(),
          MemExpr->getTemplateKeywordLoc(), TemplateArgs);
      DRE->setHadMultipleCandidates(MemExpr->getNumDecls() > 1);
      return DRE;
    } else {
      SourceLocation Loc = MemExpr->getMemberLoc();
      if (MemExpr->getQualifier())
        Loc = MemExpr->getQualifierLoc().getBeginLoc();
      Base =
          BuildCXXThisExpr(Loc, MemExpr->getBaseType(), /*IsImplicit=*/true);
    }
  } else
    Base = MemExpr->getBase();

  ExprValueKind valueKind;
  QualType type;
  if (cast<CXXMethodDecl>(Fn)->isStatic()) {
    valueKind = VK_LValue;
    type = Fn->getType();
  } else {
    valueKind = VK_PRValue;
    type = Context.BoundMemberTy;
  }

  return BuildMemberExpr(
      Base, MemExpr->isArrow(), MemExpr->getOperatorLoc(),
      MemExpr->getQualifierLoc(), MemExpr->getTemplateKeywordLoc(), Fn, Found,
      /*HadMultipleCandidates=*/true, MemExpr->getMemberNameInfo(),
      type, valueKind, OK_Ordinary, TemplateArgs);
}

llvm_unreachable("Invalid reference to overloaded function")__builtin_unreachable();
15170}

15172ExprResult Sema::FixOverloadedFunctionReference(ExprResult E,
                                              DeclAccessPair Found,
                                              FunctionDecl *Fn) {
return FixOverloadedFunctionReference(E.get(), Found, Fn);
15176}