/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 2293, column 32 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
/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 &&
1
Assuming field 'CPlusPlus' is 0→
    (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) {
2
←
Taking false branch→
  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 (argIsLValue2.1
'argIsLValue' is false
1
'argIsLValue' is false
 &&
3
←
Taking false branch→
    !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()) {
4
←
Taking false branch→
  // 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)) {
5
←
Assuming the condition is false→
6
←
Taking false branch→
  // 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)) {
7
←
Taking false branch→
  // Integral promotion (C++ 4.5).
  SCS.Second = ICK_Integral_Promotion;
  FromType = ToType.getUnqualifiedType();
} else if (S.IsFloatingPointPromotion(FromType, ToType)) {
8
←
Taking false branch→
  // Floating point promotion (C++ 4.6).
  SCS.Second = ICK_Floating_Promotion;
  FromType = ToType.getUnqualifiedType();
} else if (S.IsComplexPromotion(FromType, ToType)) {
9
←
Taking false branch→
  // 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() &&
10
←
Assuming the condition is false→
           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()) {
11
←
Assuming the condition is false→
  // 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() &&
12
←
Assuming the condition is false→
            ToType->isIntegralType(S.Context)) ||
           (FromType->isIntegralOrUnscopedEnumerationType() &&
13
←
Assuming the condition is false→
            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)) {
14
←
Taking false branch→
  SCS.Second = ICK_Block_Pointer_Conversion;
} else if (AllowObjCWritebackConversion &&
15
←
Assuming 'AllowObjCWritebackConversion' is false→
           S.isObjCWritebackConversion(FromType, ToType, FromType)) {
  SCS.Second = ICK_Writeback_Conversion;
} else if (S.IsPointerConversion(From, FromType, ToType, InOverloadResolution,
16
←
Calling 'Sema::IsPointerConversion'→
                                 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())
77
←
Calling 'Type::isObjCIdType'→
81
←
Returning from 'Type::isObjCIdType'→
82
←
Calling 'Type::isObjCQualifiedIdType'→
86
←
Returning from 'Type::isObjCQualifiedIdType'→
87
←
Taking false branch→
  return ToType.getUnqualifiedType();

QualType CanonFromPointee
  = Context.getCanonicalType(FromPtr->getPointeeType());
88
←
Called C++ object pointer is null
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() &&
51
←
Assuming the condition is false→
52
←
Taking false branch→
    Expr->getType()->isIntegerType() && !Expr->getType()->isEnumeralType())
  return !InOverloadResolution;

return Expr->isNullPointerConstant(Context,
55
←
Returning value, which participates in a condition later→
                  InOverloadResolution? Expr::NPC_ValueDependentIsNotNull
53
←
Assuming 'InOverloadResolution' is false→
54
←
'?' condition is false→
                                      : 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,
17
←
Calling 'Sema::isObjCPointerConversion'→
28
←
Returning from 'Sema::isObjCPointerConversion'→
29
←
Taking false branch→
                            IncompatibleObjC))
  return true;

// Conversion from a null pointer constant to any Objective-C pointer type.
if (ToType->isObjCObjectPointerType() &&
30
←
Calling 'Type::isObjCObjectPointerType'→
33
←
Returning from 'Type::isObjCObjectPointerType'→
    isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

// Blocks: Block pointers can be converted to void*.
if (FromType->isBlockPointerType() && ToType->isPointerType() &&
34
←
Taking false branch→
    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() &&
35
←
Calling 'Type::isBlockPointerType'→
38
←
Returning from 'Type::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() &&
39
←
Calling 'Type::isNullPtrType'→
46
←
Returning from 'Type::isNullPtrType'→
    isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
  ConvertedType = ToType;
  return true;
}

const PointerType* ToTypePtr = ToType->getAs<PointerType>();
47
←
Assuming the object is a 'PointerType'→
if (!ToTypePtr)
48
←
Assuming 'ToTypePtr' is non-null→
49
←
Taking false branch→
  return false;

// A null pointer constant can be converted to a pointer type (C++ 4.10p1).
if (isNullPointerConstantForConversion(From, InOverloadResolution, Context)) {
50
←
Calling 'isNullPointerConstantForConversion'→
56
←
Returning from 'isNullPointerConstantForConversion'→
57
←
Assuming the condition is false→
58
←
Taking false branch→
  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() &&
59
←
Calling 'Type::isObjCObjectPointerType'→
62
←
Returning from 'Type::isObjCObjectPointerType'→
63
←
Calling 'Type::isVoidType'→
71
←
Returning from 'Type::isVoidType'→
73
←
Taking true branch→
    !getLangOpts().ObjCAutoRefCount) {
72
←
Assuming field 'ObjCAutoRefCount' is 0→
  ConvertedType = BuildSimilarlyQualifiedPointerType(
76
←
Calling 'BuildSimilarlyQualifiedPointerType'→
                                    FromType->getAs<ObjCObjectPointerType>(),
74
←
Assuming the object is not a 'ObjCObjectPointerType'→
75
←
Passing null pointer value via 1st parameter 'FromPtr'→
                                                     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)
18
←
Assuming field 'ObjC' is not equal to 0→
19
←
Taking false branch→
  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>();
20
←
Assuming the object is not a 'ObjCObjectPointerType'→
const ObjCObjectPointerType *FromObjCPtr =
  FromType->getAs<ObjCObjectPointerType>();
21
←
Assuming the object is not a 'ObjCObjectPointerType'→

if (ToObjCPtr21.1
'ToObjCPtr' is null
1
'ToObjCPtr' is null
 && 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 *ToCPtr22.1
'ToCPtr' is null
1
'ToCPtr' is null
 = ToType->getAs<PointerType>())
22
←
Assuming the object is not a 'PointerType'→
23
←
Taking false branch→
  ToPointeeType = ToCPtr->getPointeeType();
else if (const BlockPointerType *ToBlockPtr24.1
'ToBlockPtr' is null
1
'ToBlockPtr' is null
 =
25
←
Taking false branch→
          ToType->getAs<BlockPointerType>()) {
24
←
Assuming the object is not a '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>() &&
26
←
Assuming the object is not a '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;
27
←
Returning zero, which participates in a condition later→

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}