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

Bug Summary

File:	src/gnu/usr.bin/clang/libclangSema/../../../llvm/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
Warning:	line 6189, column 13 Called C++ object pointer is null
Annotated Source Code

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

→
1//===--- SemaTemplateInstantiateDecl.cpp - C++ Template Decl Instantiation ===/
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//  This file implements C++ template instantiation for declarations.
9//
10//===----------------------------------------------------------------------===/

12#include "TreeTransform.h"
13#include "clang/AST/ASTConsumer.h"
14#include "clang/AST/ASTContext.h"
15#include "clang/AST/ASTMutationListener.h"
16#include "clang/AST/DeclTemplate.h"
17#include "clang/AST/DeclVisitor.h"
18#include "clang/AST/DependentDiagnostic.h"
19#include "clang/AST/Expr.h"
20#include "clang/AST/ExprCXX.h"
21#include "clang/AST/PrettyDeclStackTrace.h"
22#include "clang/AST/TypeLoc.h"
23#include "clang/Basic/SourceManager.h"
24#include "clang/Basic/TargetInfo.h"
25#include "clang/Sema/Initialization.h"
26#include "clang/Sema/Lookup.h"
27#include "clang/Sema/ScopeInfo.h"
28#include "clang/Sema/SemaInternal.h"
29#include "clang/Sema/Template.h"
30#include "clang/Sema/TemplateInstCallback.h"
31#include "llvm/Support/TimeProfiler.h"

33using namespace clang;

35static bool isDeclWithinFunction(const Decl *D) {
const DeclContext *DC = D->getDeclContext();
if (DC->isFunctionOrMethod())
  return true;

if (DC->isRecord())
  return cast<CXXRecordDecl>(DC)->isLocalClass();

return false;
44}

46template<typename DeclT>
47static bool SubstQualifier(Sema &SemaRef, const DeclT *OldDecl, DeclT *NewDecl,
                         const MultiLevelTemplateArgumentList &TemplateArgs) {
if (!OldDecl->getQualifierLoc())
  return false;

assert((NewDecl->getFriendObjectKind() ||((void)0)
        !OldDecl->getLexicalDeclContext()->isDependentContext()) &&((void)0)
       "non-friend with qualified name defined in dependent context")((void)0);
Sema::ContextRAII SavedContext(
    SemaRef,
    const_cast<DeclContext *>(NewDecl->getFriendObjectKind()
                                  ? NewDecl->getLexicalDeclContext()
                                  : OldDecl->getLexicalDeclContext()));

NestedNameSpecifierLoc NewQualifierLoc
    = SemaRef.SubstNestedNameSpecifierLoc(OldDecl->getQualifierLoc(),
                                          TemplateArgs);

if (!NewQualifierLoc)
  return true;

NewDecl->setQualifierInfo(NewQualifierLoc);
return false;
70}

72bool TemplateDeclInstantiator::SubstQualifier(const DeclaratorDecl *OldDecl,
                                            DeclaratorDecl *NewDecl) {
return ::SubstQualifier(SemaRef, OldDecl, NewDecl, TemplateArgs);
75}

77bool TemplateDeclInstantiator::SubstQualifier(const TagDecl *OldDecl,
                                            TagDecl *NewDecl) {
return ::SubstQualifier(SemaRef, OldDecl, NewDecl, TemplateArgs);
80}

82// Include attribute instantiation code.
83#include "clang/Sema/AttrTemplateInstantiate.inc"

85static void instantiateDependentAlignedAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AlignedAttr *Aligned, Decl *New, bool IsPackExpansion) {
if (Aligned->isAlignmentExpr()) {
  // The alignment expression is a constant expression.
  EnterExpressionEvaluationContext Unevaluated(
      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
  ExprResult Result = S.SubstExpr(Aligned->getAlignmentExpr(), TemplateArgs);
  if (!Result.isInvalid())
    S.AddAlignedAttr(New, *Aligned, Result.getAs<Expr>(), IsPackExpansion);
} else {
  TypeSourceInfo *Result = S.SubstType(Aligned->getAlignmentType(),
                                       TemplateArgs, Aligned->getLocation(),
                                       DeclarationName());
  if (Result)
    S.AddAlignedAttr(New, *Aligned, Result, IsPackExpansion);
}
102}

104static void instantiateDependentAlignedAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AlignedAttr *Aligned, Decl *New) {
if (!Aligned->isPackExpansion()) {
  instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, false);
  return;
}

SmallVector<UnexpandedParameterPack, 2> Unexpanded;
if (Aligned->isAlignmentExpr())
  S.collectUnexpandedParameterPacks(Aligned->getAlignmentExpr(),
                                    Unexpanded);
else
  S.collectUnexpandedParameterPacks(Aligned->getAlignmentType()->getTypeLoc(),
                                    Unexpanded);
assert(!Unexpanded.empty() && "Pack expansion without parameter packs?")((void)0);

// Determine whether we can expand this attribute pack yet.
bool Expand = true, RetainExpansion = false;
Optional<unsigned> NumExpansions;
// FIXME: Use the actual location of the ellipsis.
SourceLocation EllipsisLoc = Aligned->getLocation();
if (S.CheckParameterPacksForExpansion(EllipsisLoc, Aligned->getRange(),
                                      Unexpanded, TemplateArgs, Expand,
                                      RetainExpansion, NumExpansions))
  return;

if (!Expand) {
  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(S, -1);
  instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, true);
} else {
  for (unsigned I = 0; I != *NumExpansions; ++I) {
    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(S, I);
    instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, false);
  }
}
140}

142static void instantiateDependentAssumeAlignedAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AssumeAlignedAttr *Aligned, Decl *New) {
// The alignment expression is a constant expression.
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);

Expr *E, *OE = nullptr;
ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
if (Result.isInvalid())
  return;
E = Result.getAs<Expr>();

if (Aligned->getOffset()) {
  Result = S.SubstExpr(Aligned->getOffset(), TemplateArgs);
  if (Result.isInvalid())
    return;
  OE = Result.getAs<Expr>();
}

S.AddAssumeAlignedAttr(New, *Aligned, E, OE);
163}

165static void instantiateDependentAlignValueAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AlignValueAttr *Aligned, Decl *New) {
// The alignment expression is a constant expression.
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
if (!Result.isInvalid())
  S.AddAlignValueAttr(New, *Aligned, Result.getAs<Expr>());
174}

176static void instantiateDependentAllocAlignAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AllocAlignAttr *Align, Decl *New) {
Expr *Param = IntegerLiteral::Create(
    S.getASTContext(),
    llvm::APInt(64, Align->getParamIndex().getSourceIndex()),
    S.getASTContext().UnsignedLongLongTy, Align->getLocation());
S.AddAllocAlignAttr(New, *Align, Param);
184}

186static void instantiateDependentAnnotationAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AnnotateAttr *Attr, Decl *New) {
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
SmallVector<Expr *, 4> Args;
Args.reserve(Attr->args_size());
for (auto *E : Attr->args()) {
  ExprResult Result = S.SubstExpr(E, TemplateArgs);
  if (!Result.isUsable())
    return;
  Args.push_back(Result.get());
}
S.AddAnnotationAttr(New, *Attr, Attr->getAnnotation(), Args);
200}

202static Expr *instantiateDependentFunctionAttrCondition(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const Attr *A, Expr *OldCond, const Decl *Tmpl, FunctionDecl *New) {
Expr *Cond = nullptr;
{
  Sema::ContextRAII SwitchContext(S, New);
  EnterExpressionEvaluationContext Unevaluated(
      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
  ExprResult Result = S.SubstExpr(OldCond, TemplateArgs);
  if (Result.isInvalid())
    return nullptr;
  Cond = Result.getAs<Expr>();
}
if (!Cond->isTypeDependent()) {
  ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
  if (Converted.isInvalid())
    return nullptr;
  Cond = Converted.get();
}

SmallVector<PartialDiagnosticAt, 8> Diags;
if (OldCond->isValueDependent() && !Cond->isValueDependent() &&
    !Expr::isPotentialConstantExprUnevaluated(Cond, New, Diags)) {
  S.Diag(A->getLocation(), diag::err_attr_cond_never_constant_expr) << A;
  for (const auto &P : Diags)
    S.Diag(P.first, P.second);
  return nullptr;
}
return Cond;
231}

233static void instantiateDependentEnableIfAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const EnableIfAttr *EIA, const Decl *Tmpl, FunctionDecl *New) {
Expr *Cond = instantiateDependentFunctionAttrCondition(
    S, TemplateArgs, EIA, EIA->getCond(), Tmpl, New);

if (Cond)
  New->addAttr(new (S.getASTContext()) EnableIfAttr(S.getASTContext(), *EIA,
                                                    Cond, EIA->getMessage()));
242}

244static void instantiateDependentDiagnoseIfAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const DiagnoseIfAttr *DIA, const Decl *Tmpl, FunctionDecl *New) {
Expr *Cond = instantiateDependentFunctionAttrCondition(
    S, TemplateArgs, DIA, DIA->getCond(), Tmpl, New);

if (Cond)
  New->addAttr(new (S.getASTContext()) DiagnoseIfAttr(
      S.getASTContext(), *DIA, Cond, DIA->getMessage(),
      DIA->getDiagnosticType(), DIA->getArgDependent(), New));
254}

256// Constructs and adds to New a new instance of CUDALaunchBoundsAttr using
257// template A as the base and arguments from TemplateArgs.
258static void instantiateDependentCUDALaunchBoundsAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const CUDALaunchBoundsAttr &Attr, Decl *New) {
// The alignment expression is a constant expression.
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);

ExprResult Result = S.SubstExpr(Attr.getMaxThreads(), TemplateArgs);
if (Result.isInvalid())
  return;
Expr *MaxThreads = Result.getAs<Expr>();

Expr *MinBlocks = nullptr;
if (Attr.getMinBlocks()) {
  Result = S.SubstExpr(Attr.getMinBlocks(), TemplateArgs);
  if (Result.isInvalid())
    return;
  MinBlocks = Result.getAs<Expr>();
}

S.AddLaunchBoundsAttr(New, Attr, MaxThreads, MinBlocks);
279}

281static void
282instantiateDependentModeAttr(Sema &S,
                           const MultiLevelTemplateArgumentList &TemplateArgs,
                           const ModeAttr &Attr, Decl *New) {
S.AddModeAttr(New, Attr, Attr.getMode(),
              /*InInstantiation=*/true);
287}

289/// Instantiation of 'declare simd' attribute and its arguments.
290static void instantiateOMPDeclareSimdDeclAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const OMPDeclareSimdDeclAttr &Attr, Decl *New) {
// Allow 'this' in clauses with varlists.
if (auto *FTD = dyn_cast<FunctionTemplateDecl>(New))
  New = FTD->getTemplatedDecl();
auto *FD = cast<FunctionDecl>(New);
auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(FD->getDeclContext());
SmallVector<Expr *, 4> Uniforms, Aligneds, Alignments, Linears, Steps;
SmallVector<unsigned, 4> LinModifiers;

auto SubstExpr = [&](Expr *E) -> ExprResult {
  if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
    if (auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
      Sema::ContextRAII SavedContext(S, FD);
      LocalInstantiationScope Local(S);
      if (FD->getNumParams() > PVD->getFunctionScopeIndex())
        Local.InstantiatedLocal(
            PVD, FD->getParamDecl(PVD->getFunctionScopeIndex()));
      return S.SubstExpr(E, TemplateArgs);
    }
  Sema::CXXThisScopeRAII ThisScope(S, ThisContext, Qualifiers(),
                                   FD->isCXXInstanceMember());
  return S.SubstExpr(E, TemplateArgs);
};

// Substitute a single OpenMP clause, which is a potentially-evaluated
// full-expression.
auto Subst = [&](Expr *E) -> ExprResult {
  EnterExpressionEvaluationContext Evaluated(
      S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
  ExprResult Res = SubstExpr(E);
  if (Res.isInvalid())
    return Res;
  return S.ActOnFinishFullExpr(Res.get(), false);
};

ExprResult Simdlen;
if (auto *E = Attr.getSimdlen())
  Simdlen = Subst(E);

if (Attr.uniforms_size() > 0) {
  for(auto *E : Attr.uniforms()) {
    ExprResult Inst = Subst(E);
    if (Inst.isInvalid())
      continue;
    Uniforms.push_back(Inst.get());
  }
}

auto AI = Attr.alignments_begin();
for (auto *E : Attr.aligneds()) {
  ExprResult Inst = Subst(E);
  if (Inst.isInvalid())
    continue;
  Aligneds.push_back(Inst.get());
  Inst = ExprEmpty();
  if (*AI)
    Inst = S.SubstExpr(*AI, TemplateArgs);
  Alignments.push_back(Inst.get());
  ++AI;
}

auto SI = Attr.steps_begin();
for (auto *E : Attr.linears()) {
  ExprResult Inst = Subst(E);
  if (Inst.isInvalid())
    continue;
  Linears.push_back(Inst.get());
  Inst = ExprEmpty();
  if (*SI)
    Inst = S.SubstExpr(*SI, TemplateArgs);
  Steps.push_back(Inst.get());
  ++SI;
}
LinModifiers.append(Attr.modifiers_begin(), Attr.modifiers_end());
(void)S.ActOnOpenMPDeclareSimdDirective(
    S.ConvertDeclToDeclGroup(New), Attr.getBranchState(), Simdlen.get(),
    Uniforms, Aligneds, Alignments, Linears, LinModifiers, Steps,
    Attr.getRange());
370}

372/// Instantiation of 'declare variant' attribute and its arguments.
373static void instantiateOMPDeclareVariantAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const OMPDeclareVariantAttr &Attr, Decl *New) {
// Allow 'this' in clauses with varlists.
if (auto *FTD = dyn_cast<FunctionTemplateDecl>(New))
  New = FTD->getTemplatedDecl();
auto *FD = cast<FunctionDecl>(New);
auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(FD->getDeclContext());

auto &&SubstExpr = [FD, ThisContext, &S, &TemplateArgs](Expr *E) {
  if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
    if (auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
      Sema::ContextRAII SavedContext(S, FD);
      LocalInstantiationScope Local(S);
      if (FD->getNumParams() > PVD->getFunctionScopeIndex())
        Local.InstantiatedLocal(
            PVD, FD->getParamDecl(PVD->getFunctionScopeIndex()));
      return S.SubstExpr(E, TemplateArgs);
    }
  Sema::CXXThisScopeRAII ThisScope(S, ThisContext, Qualifiers(),
                                   FD->isCXXInstanceMember());
  return S.SubstExpr(E, TemplateArgs);
};

// Substitute a single OpenMP clause, which is a potentially-evaluated
// full-expression.
auto &&Subst = [&SubstExpr, &S](Expr *E) {
  EnterExpressionEvaluationContext Evaluated(
      S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
  ExprResult Res = SubstExpr(E);
  if (Res.isInvalid())
    return Res;
  return S.ActOnFinishFullExpr(Res.get(), false);
};

ExprResult VariantFuncRef;
if (Expr *E = Attr.getVariantFuncRef()) {
  // Do not mark function as is used to prevent its emission if this is the
  // only place where it is used.
  EnterExpressionEvaluationContext Unevaluated(
      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
  VariantFuncRef = Subst(E);
}

// Copy the template version of the OMPTraitInfo and run substitute on all
// score and condition expressiosn.
OMPTraitInfo &TI = S.getASTContext().getNewOMPTraitInfo();
TI = *Attr.getTraitInfos();

// Try to substitute template parameters in score and condition expressions.
auto SubstScoreOrConditionExpr = [&S, Subst](Expr *&E, bool) {
  if (E) {
    EnterExpressionEvaluationContext Unevaluated(
        S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
    ExprResult ER = Subst(E);
    if (ER.isUsable())
      E = ER.get();
    else
      return true;
  }
  return false;
};
if (TI.anyScoreOrCondition(SubstScoreOrConditionExpr))
  return;

Expr *E = VariantFuncRef.get();
// Check function/variant ref for `omp declare variant` but not for `omp
// begin declare variant` (which use implicit attributes).
Optional<std::pair<FunctionDecl *, Expr *>> DeclVarData =
    S.checkOpenMPDeclareVariantFunction(S.ConvertDeclToDeclGroup(New),
                                        VariantFuncRef.get(), TI,
                                        Attr.getRange());

if (!DeclVarData)
  return;

E = DeclVarData.getValue().second;
FD = DeclVarData.getValue().first;

if (auto *VariantDRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) {
  if (auto *VariantFD = dyn_cast<FunctionDecl>(VariantDRE->getDecl())) {
    if (auto *VariantFTD = VariantFD->getDescribedFunctionTemplate()) {
      if (!VariantFTD->isThisDeclarationADefinition())
        return;
      Sema::TentativeAnalysisScope Trap(S);
      const TemplateArgumentList *TAL = TemplateArgumentList::CreateCopy(
          S.Context, TemplateArgs.getInnermost());

      auto *SubstFD = S.InstantiateFunctionDeclaration(VariantFTD, TAL,
                                                       New->getLocation());
      if (!SubstFD)
        return;
      QualType NewType = S.Context.mergeFunctionTypes(
          SubstFD->getType(), FD->getType(),
          /* OfBlockPointer */ false,
          /* Unqualified */ false, /* AllowCXX */ true);
      if (NewType.isNull())
        return;
      S.InstantiateFunctionDefinition(
          New->getLocation(), SubstFD, /* Recursive */ true,
          /* DefinitionRequired */ false, /* AtEndOfTU */ false);
      SubstFD->setInstantiationIsPending(!SubstFD->isDefined());
      E = DeclRefExpr::Create(S.Context, NestedNameSpecifierLoc(),
                              SourceLocation(), SubstFD,
                              /* RefersToEnclosingVariableOrCapture */ false,
                              /* NameLoc */ SubstFD->getLocation(),
                              SubstFD->getType(), ExprValueKind::VK_PRValue);
    }
  }
}

S.ActOnOpenMPDeclareVariantDirective(FD, E, TI, Attr.getRange());
485}

487static void instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AMDGPUFlatWorkGroupSizeAttr &Attr, Decl *New) {
// Both min and max expression are constant expressions.
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);

ExprResult Result = S.SubstExpr(Attr.getMin(), TemplateArgs);
if (Result.isInvalid())
  return;
Expr *MinExpr = Result.getAs<Expr>();

Result = S.SubstExpr(Attr.getMax(), TemplateArgs);
if (Result.isInvalid())
  return;
Expr *MaxExpr = Result.getAs<Expr>();

S.addAMDGPUFlatWorkGroupSizeAttr(New, Attr, MinExpr, MaxExpr);
505}

507static ExplicitSpecifier
508instantiateExplicitSpecifier(Sema &S,
                           const MultiLevelTemplateArgumentList &TemplateArgs,
                           ExplicitSpecifier ES, FunctionDecl *New) {
if (!ES.getExpr())
  return ES;
Expr *OldCond = ES.getExpr();
Expr *Cond = nullptr;
{
  EnterExpressionEvaluationContext Unevaluated(
      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
  ExprResult SubstResult = S.SubstExpr(OldCond, TemplateArgs);
  if (SubstResult.isInvalid()) {
    return ExplicitSpecifier::Invalid();
  }
  Cond = SubstResult.get();
}
ExplicitSpecifier Result(Cond, ES.getKind());
if (!Cond->isTypeDependent())
  S.tryResolveExplicitSpecifier(Result);
return Result;
528}

530static void instantiateDependentAMDGPUWavesPerEUAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const AMDGPUWavesPerEUAttr &Attr, Decl *New) {
// Both min and max expression are constant expressions.
EnterExpressionEvaluationContext Unevaluated(
    S, Sema::ExpressionEvaluationContext::ConstantEvaluated);

ExprResult Result = S.SubstExpr(Attr.getMin(), TemplateArgs);
if (Result.isInvalid())
  return;
Expr *MinExpr = Result.getAs<Expr>();

Expr *MaxExpr = nullptr;
if (auto Max = Attr.getMax()) {
  Result = S.SubstExpr(Max, TemplateArgs);
  if (Result.isInvalid())
    return;
  MaxExpr = Result.getAs<Expr>();
}

S.addAMDGPUWavesPerEUAttr(New, Attr, MinExpr, MaxExpr);
551}

553// This doesn't take any template parameters, but we have a custom action that
554// needs to happen when the kernel itself is instantiated. We need to run the
555// ItaniumMangler to mark the names required to name this kernel.
556static void instantiateDependentSYCLKernelAttr(
  Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
  const SYCLKernelAttr &Attr, Decl *New) {
// Functions cannot be partially specialized, so if we are being instantiated,
// we are obviously a complete specialization. Since this attribute is only
// valid on function template declarations, we know that this is a full
// instantiation of a kernel.
S.AddSYCLKernelLambda(cast<FunctionDecl>(New));

// Evaluate whether this would change any of the already evaluated
// __builtin_sycl_unique_stable_name values.
for (auto &Itr : S.Context.SYCLUniqueStableNameEvaluatedValues) {
  const std::string &CurName = Itr.first->ComputeName(S.Context);
  if (Itr.second != CurName) {
    S.Diag(New->getLocation(),
           diag::err_kernel_invalidates_sycl_unique_stable_name);
    S.Diag(Itr.first->getLocation(),
           diag::note_sycl_unique_stable_name_evaluated_here);
    // Update this so future diagnostics work correctly.
    Itr.second = CurName;
  }
}

New->addAttr(Attr.clone(S.getASTContext()));
580}

582/// Determine whether the attribute A might be relevent to the declaration D.
583/// If not, we can skip instantiating it. The attribute may or may not have
584/// been instantiated yet.
585static bool isRelevantAttr(Sema &S, const Decl *D, const Attr *A) {
// 'preferred_name' is only relevant to the matching specialization of the
// template.
if (const auto *PNA = dyn_cast<PreferredNameAttr>(A)) {
  QualType T = PNA->getTypedefType();
  const auto *RD = cast<CXXRecordDecl>(D);
  if (!T->isDependentType() && !RD->isDependentContext() &&
      !declaresSameEntity(T->getAsCXXRecordDecl(), RD))
    return false;
  for (const auto *ExistingPNA : D->specific_attrs<PreferredNameAttr>())
    if (S.Context.hasSameType(ExistingPNA->getTypedefType(),
                              PNA->getTypedefType()))
      return false;
  return true;
}

return true;
602}

604void Sema::InstantiateAttrsForDecl(
  const MultiLevelTemplateArgumentList &TemplateArgs, const Decl *Tmpl,
  Decl *New, LateInstantiatedAttrVec *LateAttrs,
  LocalInstantiationScope *OuterMostScope) {
if (NamedDecl *ND = dyn_cast<NamedDecl>(New)) {
  // FIXME: This function is called multiple times for the same template
  // specialization. We should only instantiate attributes that were added
  // since the previous instantiation.
  for (const auto *TmplAttr : Tmpl->attrs()) {
    if (!isRelevantAttr(*this, New, TmplAttr))
      continue;

    // FIXME: If any of the special case versions from InstantiateAttrs become
    // applicable to template declaration, we'll need to add them here.
    CXXThisScopeRAII ThisScope(
        *this, dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext()),
        Qualifiers(), ND->isCXXInstanceMember());

    Attr *NewAttr = sema::instantiateTemplateAttributeForDecl(
        TmplAttr, Context, *this, TemplateArgs);
    if (NewAttr && isRelevantAttr(*this, New, NewAttr))
      New->addAttr(NewAttr);
  }
}
628}

630static Sema::RetainOwnershipKind
631attrToRetainOwnershipKind(const Attr *A) {
switch (A->getKind()) {
case clang::attr::CFConsumed:
  return Sema::RetainOwnershipKind::CF;
case clang::attr::OSConsumed:
  return Sema::RetainOwnershipKind::OS;
case clang::attr::NSConsumed:
  return Sema::RetainOwnershipKind::NS;
default:
  llvm_unreachable("Wrong argument supplied")__builtin_unreachable();
}
642}

644void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
                          const Decl *Tmpl, Decl *New,
                          LateInstantiatedAttrVec *LateAttrs,
                          LocalInstantiationScope *OuterMostScope) {
for (const auto *TmplAttr : Tmpl->attrs()) {
  if (!isRelevantAttr(*this, New, TmplAttr))
    continue;

  // FIXME: This should be generalized to more than just the AlignedAttr.
  const AlignedAttr *Aligned = dyn_cast<AlignedAttr>(TmplAttr);
  if (Aligned && Aligned->isAlignmentDependent()) {
    instantiateDependentAlignedAttr(*this, TemplateArgs, Aligned, New);
    continue;
  }

  if (const auto *AssumeAligned = dyn_cast<AssumeAlignedAttr>(TmplAttr)) {
    instantiateDependentAssumeAlignedAttr(*this, TemplateArgs, AssumeAligned, New);
    continue;
  }

  if (const auto *AlignValue = dyn_cast<AlignValueAttr>(TmplAttr)) {
    instantiateDependentAlignValueAttr(*this, TemplateArgs, AlignValue, New);
    continue;
  }

  if (const auto *AllocAlign = dyn_cast<AllocAlignAttr>(TmplAttr)) {
    instantiateDependentAllocAlignAttr(*this, TemplateArgs, AllocAlign, New);
    continue;
  }

  if (const auto *Annotate = dyn_cast<AnnotateAttr>(TmplAttr)) {
    instantiateDependentAnnotationAttr(*this, TemplateArgs, Annotate, New);
    continue;
  }

  if (const auto *EnableIf = dyn_cast<EnableIfAttr>(TmplAttr)) {
    instantiateDependentEnableIfAttr(*this, TemplateArgs, EnableIf, Tmpl,
                                     cast<FunctionDecl>(New));
    continue;
  }

  if (const auto *DiagnoseIf = dyn_cast<DiagnoseIfAttr>(TmplAttr)) {
    instantiateDependentDiagnoseIfAttr(*this, TemplateArgs, DiagnoseIf, Tmpl,
                                       cast<FunctionDecl>(New));
    continue;
  }

  if (const auto *CUDALaunchBounds =
          dyn_cast<CUDALaunchBoundsAttr>(TmplAttr)) {
    instantiateDependentCUDALaunchBoundsAttr(*this, TemplateArgs,
                                             *CUDALaunchBounds, New);
    continue;
  }

  if (const auto *Mode = dyn_cast<ModeAttr>(TmplAttr)) {
    instantiateDependentModeAttr(*this, TemplateArgs, *Mode, New);
    continue;
  }

  if (const auto *OMPAttr = dyn_cast<OMPDeclareSimdDeclAttr>(TmplAttr)) {
    instantiateOMPDeclareSimdDeclAttr(*this, TemplateArgs, *OMPAttr, New);
    continue;
  }

  if (const auto *OMPAttr = dyn_cast<OMPDeclareVariantAttr>(TmplAttr)) {
    instantiateOMPDeclareVariantAttr(*this, TemplateArgs, *OMPAttr, New);
    continue;
  }

  if (const auto *AMDGPUFlatWorkGroupSize =
          dyn_cast<AMDGPUFlatWorkGroupSizeAttr>(TmplAttr)) {
    instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
        *this, TemplateArgs, *AMDGPUFlatWorkGroupSize, New);
  }

  if (const auto *AMDGPUFlatWorkGroupSize =
          dyn_cast<AMDGPUWavesPerEUAttr>(TmplAttr)) {
    instantiateDependentAMDGPUWavesPerEUAttr(*this, TemplateArgs,
                                             *AMDGPUFlatWorkGroupSize, New);
  }

  // Existing DLL attribute on the instantiation takes precedence.
  if (TmplAttr->getKind() == attr::DLLExport ||
      TmplAttr->getKind() == attr::DLLImport) {
    if (New->hasAttr<DLLExportAttr>() || New->hasAttr<DLLImportAttr>()) {
      continue;
    }
  }

  if (const auto *ABIAttr = dyn_cast<ParameterABIAttr>(TmplAttr)) {
    AddParameterABIAttr(New, *ABIAttr, ABIAttr->getABI());
    continue;
  }

  if (isa<NSConsumedAttr>(TmplAttr) || isa<OSConsumedAttr>(TmplAttr) ||
      isa<CFConsumedAttr>(TmplAttr)) {
    AddXConsumedAttr(New, *TmplAttr, attrToRetainOwnershipKind(TmplAttr),
                     /*template instantiation=*/true);
    continue;
  }

  if (auto *A = dyn_cast<PointerAttr>(TmplAttr)) {
    if (!New->hasAttr<PointerAttr>())
      New->addAttr(A->clone(Context));
    continue;
  }

  if (auto *A = dyn_cast<OwnerAttr>(TmplAttr)) {
    if (!New->hasAttr<OwnerAttr>())
      New->addAttr(A->clone(Context));
    continue;
  }

  if (auto *A = dyn_cast<SYCLKernelAttr>(TmplAttr)) {
    instantiateDependentSYCLKernelAttr(*this, TemplateArgs, *A, New);
    continue;
  }

  assert(!TmplAttr->isPackExpansion())((void)0);
  if (TmplAttr->isLateParsed() && LateAttrs) {
    // Late parsed attributes must be instantiated and attached after the
    // enclosing class has been instantiated.  See Sema::InstantiateClass.
    LocalInstantiationScope *Saved = nullptr;
    if (CurrentInstantiationScope)
      Saved = CurrentInstantiationScope->cloneScopes(OuterMostScope);
    LateAttrs->push_back(LateInstantiatedAttribute(TmplAttr, Saved, New));
  } else {
    // Allow 'this' within late-parsed attributes.
    auto *ND = cast<NamedDecl>(New);
    auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext());
    CXXThisScopeRAII ThisScope(*this, ThisContext, Qualifiers(),
                               ND->isCXXInstanceMember());

    Attr *NewAttr = sema::instantiateTemplateAttribute(TmplAttr, Context,
                                                       *this, TemplateArgs);
    if (NewAttr && isRelevantAttr(*this, New, TmplAttr))
      New->addAttr(NewAttr);
  }
}
783}

785/// In the MS ABI, we need to instantiate default arguments of dllexported
786/// default constructors along with the constructor definition. This allows IR
787/// gen to emit a constructor closure which calls the default constructor with
788/// its default arguments.
789void Sema::InstantiateDefaultCtorDefaultArgs(CXXConstructorDecl *Ctor) {
assert(Context.getTargetInfo().getCXXABI().isMicrosoft() &&((void)0)
       Ctor->isDefaultConstructor())((void)0);
unsigned NumParams = Ctor->getNumParams();
if (NumParams == 0)
  return;
DLLExportAttr *Attr = Ctor->getAttr<DLLExportAttr>();
if (!Attr)
  return;
for (unsigned I = 0; I != NumParams; ++I) {
  (void)CheckCXXDefaultArgExpr(Attr->getLocation(), Ctor,
                                 Ctor->getParamDecl(I));
  DiscardCleanupsInEvaluationContext();
}
803}

805/// Get the previous declaration of a declaration for the purposes of template
806/// instantiation. If this finds a previous declaration, then the previous
807/// declaration of the instantiation of D should be an instantiation of the
808/// result of this function.
809template<typename DeclT>
810static DeclT *getPreviousDeclForInstantiation(DeclT *D) {
DeclT *Result = D->getPreviousDecl();

// If the declaration is within a class, and the previous declaration was
// merged from a different definition of that class, then we don't have a
// previous declaration for the purpose of template instantiation.
if (Result && isa<CXXRecordDecl>(D->getDeclContext()) &&
    D->getLexicalDeclContext() != Result->getLexicalDeclContext())
  return nullptr;

return Result;
821}

823Decl *
824TemplateDeclInstantiator::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
llvm_unreachable("Translation units cannot be instantiated")__builtin_unreachable();
826}

828Decl *
829TemplateDeclInstantiator::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
llvm_unreachable("pragma comment cannot be instantiated")__builtin_unreachable();
831}

833Decl *TemplateDeclInstantiator::VisitPragmaDetectMismatchDecl(
  PragmaDetectMismatchDecl *D) {
llvm_unreachable("pragma comment cannot be instantiated")__builtin_unreachable();
836}

838Decl *
839TemplateDeclInstantiator::VisitExternCContextDecl(ExternCContextDecl *D) {
llvm_unreachable("extern \"C\" context cannot be instantiated")__builtin_unreachable();
841}

843Decl *TemplateDeclInstantiator::VisitMSGuidDecl(MSGuidDecl *D) {
llvm_unreachable("GUID declaration cannot be instantiated")__builtin_unreachable();
845}

847Decl *TemplateDeclInstantiator::VisitTemplateParamObjectDecl(
  TemplateParamObjectDecl *D) {
llvm_unreachable("template parameter objects cannot be instantiated")__builtin_unreachable();
850}

852Decl *
853TemplateDeclInstantiator::VisitLabelDecl(LabelDecl *D) {
LabelDecl *Inst = LabelDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                    D->getIdentifier());
Owner->addDecl(Inst);
return Inst;
858}

860Decl *
861TemplateDeclInstantiator::VisitNamespaceDecl(NamespaceDecl *D) {
llvm_unreachable("Namespaces cannot be instantiated")__builtin_unreachable();
863}

865Decl *
866TemplateDeclInstantiator::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
NamespaceAliasDecl *Inst
  = NamespaceAliasDecl::Create(SemaRef.Context, Owner,
                               D->getNamespaceLoc(),
                               D->getAliasLoc(),
                               D->getIdentifier(),
                               D->getQualifierLoc(),
                               D->getTargetNameLoc(),
                               D->getNamespace());
Owner->addDecl(Inst);
return Inst;
877}

879Decl *TemplateDeclInstantiator::InstantiateTypedefNameDecl(TypedefNameDecl *D,
                                                         bool IsTypeAlias) {
bool Invalid = false;
TypeSourceInfo *DI = D->getTypeSourceInfo();
if (DI->getType()->isInstantiationDependentType() ||
    DI->getType()->isVariablyModifiedType()) {
  DI = SemaRef.SubstType(DI, TemplateArgs,
                         D->getLocation(), D->getDeclName());
  if (!DI) {
    Invalid = true;
    DI = SemaRef.Context.getTrivialTypeSourceInfo(SemaRef.Context.IntTy);
  }
} else {
  SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
}

// HACK: 2012-10-23 g++ has a bug where it gets the value kind of ?: wrong.
// libstdc++ relies upon this bug in its implementation of common_type.  If we
// happen to be processing that implementation, fake up the g++ ?:
// semantics. See LWG issue 2141 for more information on the bug.  The bugs
// are fixed in g++ and libstdc++ 4.9.0 (2014-04-22).
const DecltypeType *DT = DI->getType()->getAs<DecltypeType>();
CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
if (DT && RD && isa<ConditionalOperator>(DT->getUnderlyingExpr()) &&
    DT->isReferenceType() &&
    RD->getEnclosingNamespaceContext() == SemaRef.getStdNamespace() &&
    RD->getIdentifier() && RD->getIdentifier()->isStr("common_type") &&
    D->getIdentifier() && D->getIdentifier()->isStr("type") &&
    SemaRef.getSourceManager().isInSystemHeader(D->getBeginLoc()))
  // Fold it to the (non-reference) type which g++ would have produced.
  DI = SemaRef.Context.getTrivialTypeSourceInfo(
    DI->getType().getNonReferenceType());

// Create the new typedef
TypedefNameDecl *Typedef;
if (IsTypeAlias)
  Typedef = TypeAliasDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                                  D->getLocation(), D->getIdentifier(), DI);
else
  Typedef = TypedefDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                                D->getLocation(), D->getIdentifier(), DI);
if (Invalid)
  Typedef->setInvalidDecl();

// If the old typedef was the name for linkage purposes of an anonymous
// tag decl, re-establish that relationship for the new typedef.
if (const TagType *oldTagType = D->getUnderlyingType()->getAs<TagType>()) {
  TagDecl *oldTag = oldTagType->getDecl();
  if (oldTag->getTypedefNameForAnonDecl() == D && !Invalid) {
    TagDecl *newTag = DI->getType()->castAs<TagType>()->getDecl();
    assert(!newTag->hasNameForLinkage())((void)0);
    newTag->setTypedefNameForAnonDecl(Typedef);
  }
}

if (TypedefNameDecl *Prev = getPreviousDeclForInstantiation(D)) {
  NamedDecl *InstPrev = SemaRef.FindInstantiatedDecl(D->getLocation(), Prev,
                                                     TemplateArgs);
  if (!InstPrev)
    return nullptr;

  TypedefNameDecl *InstPrevTypedef = cast<TypedefNameDecl>(InstPrev);

  // If the typedef types are not identical, reject them.
  SemaRef.isIncompatibleTypedef(InstPrevTypedef, Typedef);

  Typedef->setPreviousDecl(InstPrevTypedef);
}

SemaRef.InstantiateAttrs(TemplateArgs, D, Typedef);

if (D->getUnderlyingType()->getAs<DependentNameType>())
  SemaRef.inferGslPointerAttribute(Typedef);

Typedef->setAccess(D->getAccess());

return Typedef;
956}

958Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
Decl *Typedef = InstantiateTypedefNameDecl(D, /*IsTypeAlias=*/false);
if (Typedef)
  Owner->addDecl(Typedef);
return Typedef;
963}

965Decl *TemplateDeclInstantiator::VisitTypeAliasDecl(TypeAliasDecl *D) {
Decl *Typedef = InstantiateTypedefNameDecl(D, /*IsTypeAlias=*/true);
if (Typedef)
  Owner->addDecl(Typedef);
return Typedef;
970}

972Decl *
973TemplateDeclInstantiator::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
// Create a local instantiation scope for this type alias template, which
// will contain the instantiations of the template parameters.
LocalInstantiationScope Scope(SemaRef);

TemplateParameterList *TempParams = D->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

TypeAliasDecl *Pattern = D->getTemplatedDecl();

TypeAliasTemplateDecl *PrevAliasTemplate = nullptr;
if (getPreviousDeclForInstantiation<TypedefNameDecl>(Pattern)) {
  DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
  if (!Found.empty()) {
    PrevAliasTemplate = dyn_cast<TypeAliasTemplateDecl>(Found.front());
  }
}

TypeAliasDecl *AliasInst = cast_or_null<TypeAliasDecl>(
  InstantiateTypedefNameDecl(Pattern, /*IsTypeAlias=*/true));
if (!AliasInst)
  return nullptr;

TypeAliasTemplateDecl *Inst
  = TypeAliasTemplateDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                  D->getDeclName(), InstParams, AliasInst);
AliasInst->setDescribedAliasTemplate(Inst);
if (PrevAliasTemplate)
  Inst->setPreviousDecl(PrevAliasTemplate);

Inst->setAccess(D->getAccess());

if (!PrevAliasTemplate)
  Inst->setInstantiatedFromMemberTemplate(D);

Owner->addDecl(Inst);

return Inst;
1013}

1015Decl *TemplateDeclInstantiator::VisitBindingDecl(BindingDecl *D) {
auto *NewBD = BindingDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                  D->getIdentifier());
NewBD->setReferenced(D->isReferenced());
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewBD);
return NewBD;
1021}

1023Decl *TemplateDeclInstantiator::VisitDecompositionDecl(DecompositionDecl *D) {
// Transform the bindings first.
SmallVector<BindingDecl*, 16> NewBindings;
for (auto *OldBD : D->bindings())
  NewBindings.push_back(cast<BindingDecl>(VisitBindingDecl(OldBD)));
ArrayRef<BindingDecl*> NewBindingArray = NewBindings;

auto *NewDD = cast_or_null<DecompositionDecl>(
    VisitVarDecl(D, /*InstantiatingVarTemplate=*/false, &NewBindingArray));

if (!NewDD || NewDD->isInvalidDecl())
  for (auto *NewBD : NewBindings)
    NewBD->setInvalidDecl();

return NewDD;
1038}

1040Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
return VisitVarDecl(D, /*InstantiatingVarTemplate=*/false);
1042}

1044Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D,
                                           bool InstantiatingVarTemplate,
                                           ArrayRef<BindingDecl*> *Bindings) {

// Do substitution on the type of the declaration
TypeSourceInfo *DI = SemaRef.SubstType(
    D->getTypeSourceInfo(), TemplateArgs, D->getTypeSpecStartLoc(),
    D->getDeclName(), /*AllowDeducedTST*/true);
if (!DI)
  return nullptr;

if (DI->getType()->isFunctionType()) {
  SemaRef.Diag(D->getLocation(), diag::err_variable_instantiates_to_function)
    << D->isStaticDataMember() << DI->getType();
  return nullptr;
}

DeclContext *DC = Owner;
if (D->isLocalExternDecl())
  SemaRef.adjustContextForLocalExternDecl(DC);

// Build the instantiated declaration.
VarDecl *Var;
if (Bindings)
  Var = DecompositionDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
                                  D->getLocation(), DI->getType(), DI,
                                  D->getStorageClass(), *Bindings);
else
  Var = VarDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
                        D->getLocation(), D->getIdentifier(), DI->getType(),
                        DI, D->getStorageClass());

// In ARC, infer 'retaining' for variables of retainable type.
if (SemaRef.getLangOpts().ObjCAutoRefCount &&
    SemaRef.inferObjCARCLifetime(Var))
  Var->setInvalidDecl();

if (SemaRef.getLangOpts().OpenCL)
  SemaRef.deduceOpenCLAddressSpace(Var);

// Substitute the nested name specifier, if any.
if (SubstQualifier(D, Var))
  return nullptr;

SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
                                   StartingScope, InstantiatingVarTemplate);
if (D->isNRVOVariable() && !Var->isInvalidDecl()) {
  QualType RT;
  if (auto *F = dyn_cast<FunctionDecl>(DC))
    RT = F->getReturnType();
  else if (isa<BlockDecl>(DC))
    RT = cast<FunctionType>(SemaRef.getCurBlock()->FunctionType)
             ->getReturnType();
  else
    llvm_unreachable("Unknown context type")__builtin_unreachable();

  // This is the last chance we have of checking copy elision eligibility
  // for functions in dependent contexts. The sema actions for building
  // the return statement during template instantiation will have no effect
  // regarding copy elision, since NRVO propagation runs on the scope exit
  // actions, and these are not run on instantiation.
  // This might run through some VarDecls which were returned from non-taken
  // 'if constexpr' branches, and these will end up being constructed on the
  // return slot even if they will never be returned, as a sort of accidental
  // 'optimization'. Notably, functions with 'auto' return types won't have it
  // deduced by this point. Coupled with the limitation described
  // previously, this makes it very hard to support copy elision for these.
  Sema::NamedReturnInfo Info = SemaRef.getNamedReturnInfo(Var);
  bool NRVO = SemaRef.getCopyElisionCandidate(Info, RT) != nullptr;
  Var->setNRVOVariable(NRVO);
}

Var->setImplicit(D->isImplicit());

if (Var->isStaticLocal())
  SemaRef.CheckStaticLocalForDllExport(Var);

return Var;
1122}

1124Decl *TemplateDeclInstantiator::VisitAccessSpecDecl(AccessSpecDecl *D) {
AccessSpecDecl* AD
  = AccessSpecDecl::Create(SemaRef.Context, D->getAccess(), Owner,
                           D->getAccessSpecifierLoc(), D->getColonLoc());
Owner->addHiddenDecl(AD);
return AD;
1130}

1132Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
bool Invalid = false;
TypeSourceInfo *DI = D->getTypeSourceInfo();
if (DI->getType()->isInstantiationDependentType() ||
    DI->getType()->isVariablyModifiedType())  {
  DI = SemaRef.SubstType(DI, TemplateArgs,
                         D->getLocation(), D->getDeclName());
  if (!DI) {
    DI = D->getTypeSourceInfo();
    Invalid = true;
  } else if (DI->getType()->isFunctionType()) {
    // C++ [temp.arg.type]p3:
    //   If a declaration acquires a function type through a type
    //   dependent on a template-parameter and this causes a
    //   declaration that does not use the syntactic form of a
    //   function declarator to have function type, the program is
    //   ill-formed.
    SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
      << DI->getType();
    Invalid = true;
  }
} else {
  SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
}

Expr *BitWidth = D->getBitWidth();
if (Invalid)
  BitWidth = nullptr;
else if (BitWidth) {
  // The bit-width expression is a constant expression.
  EnterExpressionEvaluationContext Unevaluated(
      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);

  ExprResult InstantiatedBitWidth
    = SemaRef.SubstExpr(BitWidth, TemplateArgs);
  if (InstantiatedBitWidth.isInvalid()) {
    Invalid = true;
    BitWidth = nullptr;
  } else
    BitWidth = InstantiatedBitWidth.getAs<Expr>();
}

FieldDecl *Field = SemaRef.CheckFieldDecl(D->getDeclName(),
                                          DI->getType(), DI,
                                          cast<RecordDecl>(Owner),
                                          D->getLocation(),
                                          D->isMutable(),
                                          BitWidth,
                                          D->getInClassInitStyle(),
                                          D->getInnerLocStart(),
                                          D->getAccess(),
                                          nullptr);
if (!Field) {
  cast<Decl>(Owner)->setInvalidDecl();
  return nullptr;
}

SemaRef.InstantiateAttrs(TemplateArgs, D, Field, LateAttrs, StartingScope);

if (Field->hasAttrs())
  SemaRef.CheckAlignasUnderalignment(Field);

if (Invalid)
  Field->setInvalidDecl();

if (!Field->getDeclName()) {
  // Keep track of where this decl came from.
  SemaRef.Context.setInstantiatedFromUnnamedFieldDecl(Field, D);
}
if (CXXRecordDecl *Parent= dyn_cast<CXXRecordDecl>(Field->getDeclContext())) {
  if (Parent->isAnonymousStructOrUnion() &&
      Parent->getRedeclContext()->isFunctionOrMethod())
    SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Field);
}

Field->setImplicit(D->isImplicit());
Field->setAccess(D->getAccess());
Owner->addDecl(Field);

return Field;
1212}

1214Decl *TemplateDeclInstantiator::VisitMSPropertyDecl(MSPropertyDecl *D) {
bool Invalid = false;
TypeSourceInfo *DI = D->getTypeSourceInfo();

if (DI->getType()->isVariablyModifiedType()) {
  SemaRef.Diag(D->getLocation(), diag::err_property_is_variably_modified)
    << D;
  Invalid = true;
} else if (DI->getType()->isInstantiationDependentType())  {
  DI = SemaRef.SubstType(DI, TemplateArgs,
                         D->getLocation(), D->getDeclName());
  if (!DI) {
    DI = D->getTypeSourceInfo();
    Invalid = true;
  } else if (DI->getType()->isFunctionType()) {
    // C++ [temp.arg.type]p3:
    //   If a declaration acquires a function type through a type
    //   dependent on a template-parameter and this causes a
    //   declaration that does not use the syntactic form of a
    //   function declarator to have function type, the program is
    //   ill-formed.
    SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
    << DI->getType();
    Invalid = true;
  }
} else {
  SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
}

MSPropertyDecl *Property = MSPropertyDecl::Create(
    SemaRef.Context, Owner, D->getLocation(), D->getDeclName(), DI->getType(),
    DI, D->getBeginLoc(), D->getGetterId(), D->getSetterId());

SemaRef.InstantiateAttrs(TemplateArgs, D, Property, LateAttrs,
                         StartingScope);

if (Invalid)
  Property->setInvalidDecl();

Property->setAccess(D->getAccess());
Owner->addDecl(Property);

return Property;
1257}

1259Decl *TemplateDeclInstantiator::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
NamedDecl **NamedChain =
  new (SemaRef.Context)NamedDecl*[D->getChainingSize()];

int i = 0;
for (auto *PI : D->chain()) {
  NamedDecl *Next = SemaRef.FindInstantiatedDecl(D->getLocation(), PI,
                                            TemplateArgs);
  if (!Next)
    return nullptr;

  NamedChain[i++] = Next;
}

QualType T = cast<FieldDecl>(NamedChain[i-1])->getType();
IndirectFieldDecl *IndirectField = IndirectFieldDecl::Create(
    SemaRef.Context, Owner, D->getLocation(), D->getIdentifier(), T,
    {NamedChain, D->getChainingSize()});

for (const auto *Attr : D->attrs())
  IndirectField->addAttr(Attr->clone(SemaRef.Context));

IndirectField->setImplicit(D->isImplicit());
IndirectField->setAccess(D->getAccess());
Owner->addDecl(IndirectField);
return IndirectField;
1285}

1287Decl *TemplateDeclInstantiator::VisitFriendDecl(FriendDecl *D) {
// Handle friend type expressions by simply substituting template
// parameters into the pattern type and checking the result.
if (TypeSourceInfo *Ty = D->getFriendType()) {
  TypeSourceInfo *InstTy;
  // If this is an unsupported friend, don't bother substituting template
  // arguments into it. The actual type referred to won't be used by any
  // parts of Clang, and may not be valid for instantiating. Just use the
  // same info for the instantiated friend.
  if (D->isUnsupportedFriend()) {
    InstTy = Ty;
  } else {
    InstTy = SemaRef.SubstType(Ty, TemplateArgs,
                               D->getLocation(), DeclarationName());
  }
  if (!InstTy)
    return nullptr;

  FriendDecl *FD = SemaRef.CheckFriendTypeDecl(D->getBeginLoc(),
                                               D->getFriendLoc(), InstTy);
  if (!FD)
    return nullptr;

  FD->setAccess(AS_public);
  FD->setUnsupportedFriend(D->isUnsupportedFriend());
  Owner->addDecl(FD);
  return FD;
}

NamedDecl *ND = D->getFriendDecl();
assert(ND && "friend decl must be a decl or a type!")((void)0);

// All of the Visit implementations for the various potential friend
// declarations have to be carefully written to work for friend
// objects, with the most important detail being that the target
// decl should almost certainly not be placed in Owner.
Decl *NewND = Visit(ND);
if (!NewND) return nullptr;

FriendDecl *FD =
  FriendDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                     cast<NamedDecl>(NewND), D->getFriendLoc());
FD->setAccess(AS_public);
FD->setUnsupportedFriend(D->isUnsupportedFriend());
Owner->addDecl(FD);
return FD;
1333}

1335Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
Expr *AssertExpr = D->getAssertExpr();

// The expression in a static assertion is a constant expression.
EnterExpressionEvaluationContext Unevaluated(
    SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);

ExprResult InstantiatedAssertExpr
  = SemaRef.SubstExpr(AssertExpr, TemplateArgs);
if (InstantiatedAssertExpr.isInvalid())
  return nullptr;

return SemaRef.BuildStaticAssertDeclaration(D->getLocation(),
                                            InstantiatedAssertExpr.get(),
                                            D->getMessage(),
                                            D->getRParenLoc(),
                                            D->isFailed());
1352}

1354Decl *TemplateDeclInstantiator::VisitEnumDecl(EnumDecl *D) {
EnumDecl *PrevDecl = nullptr;
if (EnumDecl *PatternPrev = getPreviousDeclForInstantiation(D)) {
  NamedDecl *Prev = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                 PatternPrev,
                                                 TemplateArgs);
  if (!Prev) return nullptr;
  PrevDecl = cast<EnumDecl>(Prev);
}

EnumDecl *Enum =
    EnumDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                     D->getLocation(), D->getIdentifier(), PrevDecl,
                     D->isScoped(), D->isScopedUsingClassTag(), D->isFixed());
if (D->isFixed()) {
  if (TypeSourceInfo *TI = D->getIntegerTypeSourceInfo()) {
    // If we have type source information for the underlying type, it means it
    // has been explicitly set by the user. Perform substitution on it before
    // moving on.
    SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
    TypeSourceInfo *NewTI = SemaRef.SubstType(TI, TemplateArgs, UnderlyingLoc,
                                              DeclarationName());
    if (!NewTI || SemaRef.CheckEnumUnderlyingType(NewTI))
      Enum->setIntegerType(SemaRef.Context.IntTy);
    else
      Enum->setIntegerTypeSourceInfo(NewTI);
  } else {
    assert(!D->getIntegerType()->isDependentType()((void)0)
           && "Dependent type without type source info")((void)0);
    Enum->setIntegerType(D->getIntegerType());
  }
}

SemaRef.InstantiateAttrs(TemplateArgs, D, Enum);

Enum->setInstantiationOfMemberEnum(D, TSK_ImplicitInstantiation);
Enum->setAccess(D->getAccess());
// Forward the mangling number from the template to the instantiated decl.
SemaRef.Context.setManglingNumber(Enum, SemaRef.Context.getManglingNumber(D));
// See if the old tag was defined along with a declarator.
// If it did, mark the new tag as being associated with that declarator.
if (DeclaratorDecl *DD = SemaRef.Context.getDeclaratorForUnnamedTagDecl(D))
  SemaRef.Context.addDeclaratorForUnnamedTagDecl(Enum, DD);
// See if the old tag was defined along with a typedef.
// If it did, mark the new tag as being associated with that typedef.
if (TypedefNameDecl *TND = SemaRef.Context.getTypedefNameForUnnamedTagDecl(D))
  SemaRef.Context.addTypedefNameForUnnamedTagDecl(Enum, TND);
if (SubstQualifier(D, Enum)) return nullptr;
Owner->addDecl(Enum);

EnumDecl *Def = D->getDefinition();
if (Def && Def != D) {
  // If this is an out-of-line definition of an enum member template, check
  // that the underlying types match in the instantiation of both
  // declarations.
  if (TypeSourceInfo *TI = Def->getIntegerTypeSourceInfo()) {
    SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
    QualType DefnUnderlying =
      SemaRef.SubstType(TI->getType(), TemplateArgs,
                        UnderlyingLoc, DeclarationName());
    SemaRef.CheckEnumRedeclaration(Def->getLocation(), Def->isScoped(),
                                   DefnUnderlying, /*IsFixed=*/true, Enum);
  }
}

// C++11 [temp.inst]p1: The implicit instantiation of a class template
// specialization causes the implicit instantiation of the declarations, but
// not the definitions of scoped member enumerations.
//
// DR1484 clarifies that enumeration definitions inside of a template
// declaration aren't considered entities that can be separately instantiated
// from the rest of the entity they are declared inside of.
if (isDeclWithinFunction(D) ? D == Def : Def && !Enum->isScoped()) {
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Enum);
  InstantiateEnumDefinition(Enum, Def);
}

return Enum;
1432}

1434void TemplateDeclInstantiator::InstantiateEnumDefinition(
  EnumDecl *Enum, EnumDecl *Pattern) {
Enum->startDefinition();

// Update the location to refer to the definition.
Enum->setLocation(Pattern->getLocation());

SmallVector<Decl*, 4> Enumerators;

EnumConstantDecl *LastEnumConst = nullptr;
for (auto *EC : Pattern->enumerators()) {
  // The specified value for the enumerator.
  ExprResult Value((Expr *)nullptr);
  if (Expr *UninstValue = EC->getInitExpr()) {
    // The enumerator's value expression is a constant expression.
    EnterExpressionEvaluationContext Unevaluated(
        SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);

    Value = SemaRef.SubstExpr(UninstValue, TemplateArgs);
  }

  // Drop the initial value and continue.
  bool isInvalid = false;
  if (Value.isInvalid()) {
    Value = nullptr;
    isInvalid = true;
  }

  EnumConstantDecl *EnumConst
    = SemaRef.CheckEnumConstant(Enum, LastEnumConst,
                                EC->getLocation(), EC->getIdentifier(),
                                Value.get());

  if (isInvalid) {
    if (EnumConst)
      EnumConst->setInvalidDecl();
    Enum->setInvalidDecl();
  }

  if (EnumConst) {
    SemaRef.InstantiateAttrs(TemplateArgs, EC, EnumConst);

    EnumConst->setAccess(Enum->getAccess());
    Enum->addDecl(EnumConst);
    Enumerators.push_back(EnumConst);
    LastEnumConst = EnumConst;

    if (Pattern->getDeclContext()->isFunctionOrMethod() &&
        !Enum->isScoped()) {
      // If the enumeration is within a function or method, record the enum
      // constant as a local.
      SemaRef.CurrentInstantiationScope->InstantiatedLocal(EC, EnumConst);
    }
  }
}

SemaRef.ActOnEnumBody(Enum->getLocation(), Enum->getBraceRange(), Enum,
                      Enumerators, nullptr, ParsedAttributesView());
1492}

1494Decl *TemplateDeclInstantiator::VisitEnumConstantDecl(EnumConstantDecl *D) {
llvm_unreachable("EnumConstantDecls can only occur within EnumDecls.")__builtin_unreachable();
1496}

1498Decl *
1499TemplateDeclInstantiator::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
llvm_unreachable("BuiltinTemplateDecls cannot be instantiated.")__builtin_unreachable();
1501}

1503Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
bool isFriend = (D->getFriendObjectKind() != Decl::FOK_None);

// Create a local instantiation scope for this class template, which
// will contain the instantiations of the template parameters.
LocalInstantiationScope Scope(SemaRef);
TemplateParameterList *TempParams = D->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

CXXRecordDecl *Pattern = D->getTemplatedDecl();

// Instantiate the qualifier.  We have to do this first in case
// we're a friend declaration, because if we are then we need to put
// the new declaration in the appropriate context.
NestedNameSpecifierLoc QualifierLoc = Pattern->getQualifierLoc();
if (QualifierLoc) {
  QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                                     TemplateArgs);
  if (!QualifierLoc)
    return nullptr;
}

CXXRecordDecl *PrevDecl = nullptr;
ClassTemplateDecl *PrevClassTemplate = nullptr;

if (!isFriend && getPreviousDeclForInstantiation(Pattern)) {
  DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
  if (!Found.empty()) {
    PrevClassTemplate = dyn_cast<ClassTemplateDecl>(Found.front());
    if (PrevClassTemplate)
      PrevDecl = PrevClassTemplate->getTemplatedDecl();
  }
}

// If this isn't a friend, then it's a member template, in which
// case we just want to build the instantiation in the
// specialization.  If it is a friend, we want to build it in
// the appropriate context.
DeclContext *DC = Owner;
if (isFriend) {
  if (QualifierLoc) {
    CXXScopeSpec SS;
    SS.Adopt(QualifierLoc);
    DC = SemaRef.computeDeclContext(SS);
    if (!DC) return nullptr;
  } else {
    DC = SemaRef.FindInstantiatedContext(Pattern->getLocation(),
                                         Pattern->getDeclContext(),
                                         TemplateArgs);
  }

  // Look for a previous declaration of the template in the owning
  // context.
  LookupResult R(SemaRef, Pattern->getDeclName(), Pattern->getLocation(),
                 Sema::LookupOrdinaryName,
                 SemaRef.forRedeclarationInCurContext());
  SemaRef.LookupQualifiedName(R, DC);

  if (R.isSingleResult()) {
    PrevClassTemplate = R.getAsSingle<ClassTemplateDecl>();
    if (PrevClassTemplate)
      PrevDecl = PrevClassTemplate->getTemplatedDecl();
  }

  if (!PrevClassTemplate && QualifierLoc) {
    SemaRef.Diag(Pattern->getLocation(), diag::err_not_tag_in_scope)
      << D->getTemplatedDecl()->getTagKind() << Pattern->getDeclName() << DC
      << QualifierLoc.getSourceRange();
    return nullptr;
  }

  if (PrevClassTemplate) {
    TemplateParameterList *PrevParams
      = PrevClassTemplate->getMostRecentDecl()->getTemplateParameters();

    // Make sure the parameter lists match.
    if (!SemaRef.TemplateParameterListsAreEqual(InstParams, PrevParams, true,
                                                Sema::TPL_TemplateMatch))
      return nullptr;

    // Do some additional validation, then merge default arguments
    // from the existing declarations.
    if (SemaRef.CheckTemplateParameterList(InstParams, PrevParams,
                                           Sema::TPC_ClassTemplate))
      return nullptr;
  }
}

CXXRecordDecl *RecordInst = CXXRecordDecl::Create(
    SemaRef.Context, Pattern->getTagKind(), DC, Pattern->getBeginLoc(),
    Pattern->getLocation(), Pattern->getIdentifier(), PrevDecl,
    /*DelayTypeCreation=*/true);

if (QualifierLoc)
  RecordInst->setQualifierInfo(QualifierLoc);

SemaRef.InstantiateAttrsForDecl(TemplateArgs, Pattern, RecordInst, LateAttrs,
                                                            StartingScope);

ClassTemplateDecl *Inst
  = ClassTemplateDecl::Create(SemaRef.Context, DC, D->getLocation(),
                              D->getIdentifier(), InstParams, RecordInst);
assert(!(isFriend && Owner->isDependentContext()))((void)0);
Inst->setPreviousDecl(PrevClassTemplate);

RecordInst->setDescribedClassTemplate(Inst);

if (isFriend) {
  if (PrevClassTemplate)
    Inst->setAccess(PrevClassTemplate->getAccess());
  else
    Inst->setAccess(D->getAccess());

  Inst->setObjectOfFriendDecl();
  // TODO: do we want to track the instantiation progeny of this
  // friend target decl?
} else {
  Inst->setAccess(D->getAccess());
  if (!PrevClassTemplate)
    Inst->setInstantiatedFromMemberTemplate(D);
}

// Trigger creation of the type for the instantiation.
SemaRef.Context.getInjectedClassNameType(RecordInst,
                                  Inst->getInjectedClassNameSpecialization());

// Finish handling of friends.
if (isFriend) {
  DC->makeDeclVisibleInContext(Inst);
  Inst->setLexicalDeclContext(Owner);
  RecordInst->setLexicalDeclContext(Owner);
  return Inst;
}

if (D->isOutOfLine()) {
  Inst->setLexicalDeclContext(D->getLexicalDeclContext());
  RecordInst->setLexicalDeclContext(D->getLexicalDeclContext());
}

Owner->addDecl(Inst);

if (!PrevClassTemplate) {
  // Queue up any out-of-line partial specializations of this member
  // class template; the client will force their instantiation once
  // the enclosing class has been instantiated.
  SmallVector<ClassTemplatePartialSpecializationDecl *, 4> PartialSpecs;
  D->getPartialSpecializations(PartialSpecs);
  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I)
    if (PartialSpecs[I]->getFirstDecl()->isOutOfLine())
      OutOfLinePartialSpecs.push_back(std::make_pair(Inst, PartialSpecs[I]));
}

return Inst;
1658}

1660Decl *
1661TemplateDeclInstantiator::VisitClassTemplatePartialSpecializationDecl(
                                 ClassTemplatePartialSpecializationDecl *D) {
ClassTemplateDecl *ClassTemplate = D->getSpecializedTemplate();

// Lookup the already-instantiated declaration in the instantiation
// of the class template and return that.
DeclContext::lookup_result Found
  = Owner->lookup(ClassTemplate->getDeclName());
if (Found.empty())
  return nullptr;

ClassTemplateDecl *InstClassTemplate
  = dyn_cast<ClassTemplateDecl>(Found.front());
if (!InstClassTemplate)
  return nullptr;

if (ClassTemplatePartialSpecializationDecl *Result
      = InstClassTemplate->findPartialSpecInstantiatedFromMember(D))
  return Result;

return InstantiateClassTemplatePartialSpecialization(InstClassTemplate, D);
1682}

1684Decl *TemplateDeclInstantiator::VisitVarTemplateDecl(VarTemplateDecl *D) {
assert(D->getTemplatedDecl()->isStaticDataMember() &&((void)0)
       "Only static data member templates are allowed.")((void)0);

// Create a local instantiation scope for this variable template, which
// will contain the instantiations of the template parameters.
LocalInstantiationScope Scope(SemaRef);
TemplateParameterList *TempParams = D->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

VarDecl *Pattern = D->getTemplatedDecl();
VarTemplateDecl *PrevVarTemplate = nullptr;

if (getPreviousDeclForInstantiation(Pattern)) {
  DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
  if (!Found.empty())
    PrevVarTemplate = dyn_cast<VarTemplateDecl>(Found.front());
}

VarDecl *VarInst =
    cast_or_null<VarDecl>(VisitVarDecl(Pattern,
                                       /*InstantiatingVarTemplate=*/true));
if (!VarInst) return nullptr;

DeclContext *DC = Owner;

VarTemplateDecl *Inst = VarTemplateDecl::Create(
    SemaRef.Context, DC, D->getLocation(), D->getIdentifier(), InstParams,
    VarInst);
VarInst->setDescribedVarTemplate(Inst);
Inst->setPreviousDecl(PrevVarTemplate);

Inst->setAccess(D->getAccess());
if (!PrevVarTemplate)
  Inst->setInstantiatedFromMemberTemplate(D);

if (D->isOutOfLine()) {
  Inst->setLexicalDeclContext(D->getLexicalDeclContext());
  VarInst->setLexicalDeclContext(D->getLexicalDeclContext());
}

Owner->addDecl(Inst);

if (!PrevVarTemplate) {
  // Queue up any out-of-line partial specializations of this member
  // variable template; the client will force their instantiation once
  // the enclosing class has been instantiated.
  SmallVector<VarTemplatePartialSpecializationDecl *, 4> PartialSpecs;
  D->getPartialSpecializations(PartialSpecs);
  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I)
    if (PartialSpecs[I]->getFirstDecl()->isOutOfLine())
      OutOfLineVarPartialSpecs.push_back(
          std::make_pair(Inst, PartialSpecs[I]));
}

return Inst;
1742}

1744Decl *TemplateDeclInstantiator::VisitVarTemplatePartialSpecializationDecl(
  VarTemplatePartialSpecializationDecl *D) {
assert(D->isStaticDataMember() &&((void)0)
       "Only static data member templates are allowed.")((void)0);

VarTemplateDecl *VarTemplate = D->getSpecializedTemplate();

// Lookup the already-instantiated declaration and return that.
DeclContext::lookup_result Found = Owner->lookup(VarTemplate->getDeclName());
assert(!Found.empty() && "Instantiation found nothing?")((void)0);

VarTemplateDecl *InstVarTemplate = dyn_cast<VarTemplateDecl>(Found.front());
assert(InstVarTemplate && "Instantiation did not find a variable template?")((void)0);

if (VarTemplatePartialSpecializationDecl *Result =
        InstVarTemplate->findPartialSpecInstantiatedFromMember(D))
  return Result;

return InstantiateVarTemplatePartialSpecialization(InstVarTemplate, D);
1763}

1765Decl *
1766TemplateDeclInstantiator::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
// Create a local instantiation scope for this function template, which
// will contain the instantiations of the template parameters and then get
// merged with the local instantiation scope for the function template
// itself.
LocalInstantiationScope Scope(SemaRef);

TemplateParameterList *TempParams = D->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

FunctionDecl *Instantiated = nullptr;
if (CXXMethodDecl *DMethod = dyn_cast<CXXMethodDecl>(D->getTemplatedDecl()))
  Instantiated = cast_or_null<FunctionDecl>(VisitCXXMethodDecl(DMethod,
                                                               InstParams));
else
  Instantiated = cast_or_null<FunctionDecl>(VisitFunctionDecl(
                                                        D->getTemplatedDecl(),
                                                              InstParams));

if (!Instantiated)
  return nullptr;

// Link the instantiated function template declaration to the function
// template from which it was instantiated.
FunctionTemplateDecl *InstTemplate
  = Instantiated->getDescribedFunctionTemplate();
InstTemplate->setAccess(D->getAccess());
assert(InstTemplate &&((void)0)
       "VisitFunctionDecl/CXXMethodDecl didn't create a template!")((void)0);

bool isFriend = (InstTemplate->getFriendObjectKind() != Decl::FOK_None);

// Link the instantiation back to the pattern *unless* this is a
// non-definition friend declaration.
if (!InstTemplate->getInstantiatedFromMemberTemplate() &&
    !(isFriend && !D->getTemplatedDecl()->isThisDeclarationADefinition()))
  InstTemplate->setInstantiatedFromMemberTemplate(D);

// Make declarations visible in the appropriate context.
if (!isFriend) {
  Owner->addDecl(InstTemplate);
} else if (InstTemplate->getDeclContext()->isRecord() &&
           !getPreviousDeclForInstantiation(D)) {
  SemaRef.CheckFriendAccess(InstTemplate);
}

return InstTemplate;
1815}

1817Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
CXXRecordDecl *PrevDecl = nullptr;
if (D->isInjectedClassName())
  PrevDecl = cast<CXXRecordDecl>(Owner);
else if (CXXRecordDecl *PatternPrev = getPreviousDeclForInstantiation(D)) {
  NamedDecl *Prev = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                 PatternPrev,
                                                 TemplateArgs);
  if (!Prev) return nullptr;
  PrevDecl = cast<CXXRecordDecl>(Prev);
}

CXXRecordDecl *Record = nullptr;
if (D->isLambda())
  Record = CXXRecordDecl::CreateLambda(
      SemaRef.Context, Owner, D->getLambdaTypeInfo(), D->getLocation(),
      D->isDependentLambda(), D->isGenericLambda(),
      D->getLambdaCaptureDefault());
else
  Record = CXXRecordDecl::Create(SemaRef.Context, D->getTagKind(), Owner,
                                 D->getBeginLoc(), D->getLocation(),
                                 D->getIdentifier(), PrevDecl);

// Substitute the nested name specifier, if any.
if (SubstQualifier(D, Record))
  return nullptr;

SemaRef.InstantiateAttrsForDecl(TemplateArgs, D, Record, LateAttrs,
                                                            StartingScope);

Record->setImplicit(D->isImplicit());
// FIXME: Check against AS_none is an ugly hack to work around the issue that
// the tag decls introduced by friend class declarations don't have an access
// specifier. Remove once this area of the code gets sorted out.
if (D->getAccess() != AS_none)
  Record->setAccess(D->getAccess());
if (!D->isInjectedClassName())
  Record->setInstantiationOfMemberClass(D, TSK_ImplicitInstantiation);

// If the original function was part of a friend declaration,
// inherit its namespace state.
if (D->getFriendObjectKind())
  Record->setObjectOfFriendDecl();

// Make sure that anonymous structs and unions are recorded.
if (D->isAnonymousStructOrUnion())
  Record->setAnonymousStructOrUnion(true);

if (D->isLocalClass())
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Record);

// Forward the mangling number from the template to the instantiated decl.
SemaRef.Context.setManglingNumber(Record,
                                  SemaRef.Context.getManglingNumber(D));

// See if the old tag was defined along with a declarator.
// If it did, mark the new tag as being associated with that declarator.
if (DeclaratorDecl *DD = SemaRef.Context.getDeclaratorForUnnamedTagDecl(D))
  SemaRef.Context.addDeclaratorForUnnamedTagDecl(Record, DD);

// See if the old tag was defined along with a typedef.
// If it did, mark the new tag as being associated with that typedef.
if (TypedefNameDecl *TND = SemaRef.Context.getTypedefNameForUnnamedTagDecl(D))
  SemaRef.Context.addTypedefNameForUnnamedTagDecl(Record, TND);

Owner->addDecl(Record);

// DR1484 clarifies that the members of a local class are instantiated as part
// of the instantiation of their enclosing entity.
if (D->isCompleteDefinition() && D->isLocalClass()) {
  Sema::LocalEagerInstantiationScope LocalInstantiations(SemaRef);

  SemaRef.InstantiateClass(D->getLocation(), Record, D, TemplateArgs,
                           TSK_ImplicitInstantiation,
                           /*Complain=*/true);

  // For nested local classes, we will instantiate the members when we
  // reach the end of the outermost (non-nested) local class.
  if (!D->isCXXClassMember())
    SemaRef.InstantiateClassMembers(D->getLocation(), Record, TemplateArgs,
                                    TSK_ImplicitInstantiation);

  // This class may have local implicit instantiations that need to be
  // performed within this scope.
  LocalInstantiations.perform();
}

SemaRef.DiagnoseUnusedNestedTypedefs(Record);

return Record;
1907}

1909/// Adjust the given function type for an instantiation of the
1910/// given declaration, to cope with modifications to the function's type that
1911/// aren't reflected in the type-source information.
1912///
1913/// \param D The declaration we're instantiating.
1914/// \param TInfo The already-instantiated type.
1915static QualType adjustFunctionTypeForInstantiation(ASTContext &Context,
                                                 FunctionDecl *D,
                                                 TypeSourceInfo *TInfo) {
const FunctionProtoType *OrigFunc
  = D->getType()->castAs<FunctionProtoType>();
const FunctionProtoType *NewFunc
  = TInfo->getType()->castAs<FunctionProtoType>();
if (OrigFunc->getExtInfo() == NewFunc->getExtInfo())
  return TInfo->getType();

FunctionProtoType::ExtProtoInfo NewEPI = NewFunc->getExtProtoInfo();
NewEPI.ExtInfo = OrigFunc->getExtInfo();
return Context.getFunctionType(NewFunc->getReturnType(),
                               NewFunc->getParamTypes(), NewEPI);
1929}

1931/// Normal class members are of more specific types and therefore
1932/// don't make it here.  This function serves three purposes:
1933///   1) instantiating function templates
1934///   2) substituting friend declarations
1935///   3) substituting deduction guide declarations for nested class templates
1936Decl *TemplateDeclInstantiator::VisitFunctionDecl(
  FunctionDecl *D, TemplateParameterList *TemplateParams,
  RewriteKind FunctionRewriteKind) {
// Check whether there is already a function template specialization for
// this declaration.
FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
if (FunctionTemplate && !TemplateParams) {
  ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();

  void *InsertPos = nullptr;
  FunctionDecl *SpecFunc
    = FunctionTemplate->findSpecialization(Innermost, InsertPos);

  // If we already have a function template specialization, return it.
  if (SpecFunc)
    return SpecFunc;
}

bool isFriend;
if (FunctionTemplate)
  isFriend = (FunctionTemplate->getFriendObjectKind() != Decl::FOK_None);
else
  isFriend = (D->getFriendObjectKind() != Decl::FOK_None);

bool MergeWithParentScope = (TemplateParams != nullptr) ||
  Owner->isFunctionOrMethod() ||
  !(isa<Decl>(Owner) &&
    cast<Decl>(Owner)->isDefinedOutsideFunctionOrMethod());
LocalInstantiationScope Scope(SemaRef, MergeWithParentScope);

ExplicitSpecifier InstantiatedExplicitSpecifier;
if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D)) {
  InstantiatedExplicitSpecifier = instantiateExplicitSpecifier(
      SemaRef, TemplateArgs, DGuide->getExplicitSpecifier(), DGuide);
  if (InstantiatedExplicitSpecifier.isInvalid())
    return nullptr;
}

SmallVector<ParmVarDecl *, 4> Params;
TypeSourceInfo *TInfo = SubstFunctionType(D, Params);
if (!TInfo)
  return nullptr;
QualType T = adjustFunctionTypeForInstantiation(SemaRef.Context, D, TInfo);

if (TemplateParams && TemplateParams->size()) {
  auto *LastParam =
      dyn_cast<TemplateTypeParmDecl>(TemplateParams->asArray().back());
  if (LastParam && LastParam->isImplicit() &&
      LastParam->hasTypeConstraint()) {
    // In abbreviated templates, the type-constraints of invented template
    // type parameters are instantiated with the function type, invalidating
    // the TemplateParameterList which relied on the template type parameter
    // not having a type constraint. Recreate the TemplateParameterList with
    // the updated parameter list.
    TemplateParams = TemplateParameterList::Create(
        SemaRef.Context, TemplateParams->getTemplateLoc(),
        TemplateParams->getLAngleLoc(), TemplateParams->asArray(),
        TemplateParams->getRAngleLoc(), TemplateParams->getRequiresClause());
  }
}

NestedNameSpecifierLoc QualifierLoc = D->getQualifierLoc();
if (QualifierLoc) {
  QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                                     TemplateArgs);
  if (!QualifierLoc)
    return nullptr;
}

// FIXME: Concepts: Do not substitute into constraint expressions
Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
if (TrailingRequiresClause) {
  EnterExpressionEvaluationContext ConstantEvaluated(
      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
  ExprResult SubstRC = SemaRef.SubstExpr(TrailingRequiresClause,
                                         TemplateArgs);
  if (SubstRC.isInvalid())
    return nullptr;
  TrailingRequiresClause = SubstRC.get();
  if (!SemaRef.CheckConstraintExpression(TrailingRequiresClause))
    return nullptr;
}

// If we're instantiating a local function declaration, put the result
// in the enclosing namespace; otherwise we need to find the instantiated
// context.
DeclContext *DC;
if (D->isLocalExternDecl()) {
  DC = Owner;
  SemaRef.adjustContextForLocalExternDecl(DC);
} else if (isFriend && QualifierLoc) {
  CXXScopeSpec SS;
  SS.Adopt(QualifierLoc);
  DC = SemaRef.computeDeclContext(SS);
  if (!DC) return nullptr;
} else {
  DC = SemaRef.FindInstantiatedContext(D->getLocation(), D->getDeclContext(),
                                       TemplateArgs);
}

DeclarationNameInfo NameInfo
  = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);

if (FunctionRewriteKind != RewriteKind::None)
  adjustForRewrite(FunctionRewriteKind, D, T, TInfo, NameInfo);

FunctionDecl *Function;
if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D)) {
  Function = CXXDeductionGuideDecl::Create(
      SemaRef.Context, DC, D->getInnerLocStart(),
      InstantiatedExplicitSpecifier, NameInfo, T, TInfo,
      D->getSourceRange().getEnd());
  if (DGuide->isCopyDeductionCandidate())
    cast<CXXDeductionGuideDecl>(Function)->setIsCopyDeductionCandidate();
  Function->setAccess(D->getAccess());
} else {
  Function = FunctionDecl::Create(
      SemaRef.Context, DC, D->getInnerLocStart(), NameInfo, T, TInfo,
      D->getCanonicalDecl()->getStorageClass(), D->isInlineSpecified(),
      D->hasWrittenPrototype(), D->getConstexprKind(),
      TrailingRequiresClause);
  Function->setRangeEnd(D->getSourceRange().getEnd());
}

if (D->isInlined())
  Function->setImplicitlyInline();

if (QualifierLoc)
  Function->setQualifierInfo(QualifierLoc);

if (D->isLocalExternDecl())
  Function->setLocalExternDecl();

DeclContext *LexicalDC = Owner;
if (!isFriend && D->isOutOfLine() && !D->isLocalExternDecl()) {
  assert(D->getDeclContext()->isFileContext())((void)0);
  LexicalDC = D->getDeclContext();
}

Function->setLexicalDeclContext(LexicalDC);

// Attach the parameters
for (unsigned P = 0; P < Params.size(); ++P)
  if (Params[P])
    Params[P]->setOwningFunction(Function);
Function->setParams(Params);

if (TrailingRequiresClause)
  Function->setTrailingRequiresClause(TrailingRequiresClause);

if (TemplateParams) {
  // Our resulting instantiation is actually a function template, since we
  // are substituting only the outer template parameters. For example, given
  //
  //   template<typename T>
  //   struct X {
  //     template<typename U> friend void f(T, U);
  //   };
  //
  //   X<int> x;
  //
  // We are instantiating the friend function template "f" within X<int>,
  // which means substituting int for T, but leaving "f" as a friend function
  // template.
  // Build the function template itself.
  FunctionTemplate = FunctionTemplateDecl::Create(SemaRef.Context, DC,
                                                  Function->getLocation(),
                                                  Function->getDeclName(),
                                                  TemplateParams, Function);
  Function->setDescribedFunctionTemplate(FunctionTemplate);

  FunctionTemplate->setLexicalDeclContext(LexicalDC);

  if (isFriend && D->isThisDeclarationADefinition()) {
    FunctionTemplate->setInstantiatedFromMemberTemplate(
                                         D->getDescribedFunctionTemplate());
  }
} else if (FunctionTemplate) {
  // Record this function template specialization.
  ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
  Function->setFunctionTemplateSpecialization(FunctionTemplate,
                          TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                           Innermost),
                                              /*InsertPos=*/nullptr);
} else if (isFriend && D->isThisDeclarationADefinition()) {
  // Do not connect the friend to the template unless it's actually a
  // definition. We don't want non-template functions to be marked as being
  // template instantiations.
  Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
}

if (isFriend) {
  Function->setObjectOfFriendDecl();
  if (FunctionTemplateDecl *FT = Function->getDescribedFunctionTemplate())
    FT->setObjectOfFriendDecl();
}

if (InitFunctionInstantiation(Function, D))
  Function->setInvalidDecl();

bool IsExplicitSpecialization = false;

LookupResult Previous(
    SemaRef, Function->getDeclName(), SourceLocation(),
    D->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
                           : Sema::LookupOrdinaryName,
    D->isLocalExternDecl() ? Sema::ForExternalRedeclaration
                           : SemaRef.forRedeclarationInCurContext());

if (DependentFunctionTemplateSpecializationInfo *Info
      = D->getDependentSpecializationInfo()) {
  assert(isFriend && "non-friend has dependent specialization info?")((void)0);

  // Instantiate the explicit template arguments.
  TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                        Info->getRAngleLoc());
  if (SemaRef.Subst(Info->getTemplateArgs(), Info->getNumTemplateArgs(),
                    ExplicitArgs, TemplateArgs))
    return nullptr;

  // Map the candidate templates to their instantiations.
  for (unsigned I = 0, E = Info->getNumTemplates(); I != E; ++I) {
    Decl *Temp = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                              Info->getTemplate(I),
                                              TemplateArgs);
    if (!Temp) return nullptr;

    Previous.addDecl(cast<FunctionTemplateDecl>(Temp));
  }

  if (SemaRef.CheckFunctionTemplateSpecialization(Function,
                                                  &ExplicitArgs,
                                                  Previous))
    Function->setInvalidDecl();

  IsExplicitSpecialization = true;
} else if (const ASTTemplateArgumentListInfo *Info =
               D->getTemplateSpecializationArgsAsWritten()) {
  // The name of this function was written as a template-id.
  SemaRef.LookupQualifiedName(Previous, DC);

  // Instantiate the explicit template arguments.
  TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                        Info->getRAngleLoc());
  if (SemaRef.Subst(Info->getTemplateArgs(), Info->getNumTemplateArgs(),
                    ExplicitArgs, TemplateArgs))
    return nullptr;

  if (SemaRef.CheckFunctionTemplateSpecialization(Function,
                                                  &ExplicitArgs,
                                                  Previous))
    Function->setInvalidDecl();

  IsExplicitSpecialization = true;
} else if (TemplateParams || !FunctionTemplate) {
  // Look only into the namespace where the friend would be declared to
  // find a previous declaration. This is the innermost enclosing namespace,
  // as described in ActOnFriendFunctionDecl.
  SemaRef.LookupQualifiedName(Previous, DC->getRedeclContext());

  // In C++, the previous declaration we find might be a tag type
  // (class or enum). In this case, the new declaration will hide the
  // tag type. Note that this does does not apply if we're declaring a
  // typedef (C++ [dcl.typedef]p4).
  if (Previous.isSingleTagDecl())
    Previous.clear();

  // Filter out previous declarations that don't match the scope. The only
  // effect this has is to remove declarations found in inline namespaces
  // for friend declarations with unqualified names.
  SemaRef.FilterLookupForScope(Previous, DC, /*Scope*/ nullptr,
                               /*ConsiderLinkage*/ true,
                               QualifierLoc.hasQualifier());
}

SemaRef.CheckFunctionDeclaration(/*Scope*/ nullptr, Function, Previous,
                                 IsExplicitSpecialization);

// Check the template parameter list against the previous declaration. The
// goal here is to pick up default arguments added since the friend was
// declared; we know the template parameter lists match, since otherwise
// we would not have picked this template as the previous declaration.
if (isFriend && TemplateParams && FunctionTemplate->getPreviousDecl()) {
  SemaRef.CheckTemplateParameterList(
      TemplateParams,
      FunctionTemplate->getPreviousDecl()->getTemplateParameters(),
      Function->isThisDeclarationADefinition()
          ? Sema::TPC_FriendFunctionTemplateDefinition
          : Sema::TPC_FriendFunctionTemplate);
}

// If we're introducing a friend definition after the first use, trigger
// instantiation.
// FIXME: If this is a friend function template definition, we should check
// to see if any specializations have been used.
if (isFriend && D->isThisDeclarationADefinition() && Function->isUsed(false)) {
  if (MemberSpecializationInfo *MSInfo =
          Function->getMemberSpecializationInfo()) {
    if (MSInfo->getPointOfInstantiation().isInvalid()) {
      SourceLocation Loc = D->getLocation(); // FIXME
      MSInfo->setPointOfInstantiation(Loc);
      SemaRef.PendingLocalImplicitInstantiations.push_back(
          std::make_pair(Function, Loc));
    }
  }
}

if (D->isExplicitlyDefaulted()) {
  if (SubstDefaultedFunction(Function, D))
    return nullptr;
}
if (D->isDeleted())
  SemaRef.SetDeclDeleted(Function, D->getLocation());

NamedDecl *PrincipalDecl =
    (TemplateParams ? cast<NamedDecl>(FunctionTemplate) : Function);

// If this declaration lives in a different context from its lexical context,
// add it to the corresponding lookup table.
if (isFriend ||
    (Function->isLocalExternDecl() && !Function->getPreviousDecl()))
  DC->makeDeclVisibleInContext(PrincipalDecl);

if (Function->isOverloadedOperator() && !DC->isRecord() &&
    PrincipalDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
  PrincipalDecl->setNonMemberOperator();

return Function;
2264}

2266Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
  CXXMethodDecl *D, TemplateParameterList *TemplateParams,
  Optional<const ASTTemplateArgumentListInfo *> ClassScopeSpecializationArgs,
  RewriteKind FunctionRewriteKind) {
FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
if (FunctionTemplate && !TemplateParams) {
  // We are creating a function template specialization from a function
  // template. Check whether there is already a function template
  // specialization for this particular set of template arguments.
  ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();

  void *InsertPos = nullptr;
  FunctionDecl *SpecFunc
    = FunctionTemplate->findSpecialization(Innermost, InsertPos);

  // If we already have a function template specialization, return it.
  if (SpecFunc)
    return SpecFunc;
}

bool isFriend;
if (FunctionTemplate)
  isFriend = (FunctionTemplate->getFriendObjectKind() != Decl::FOK_None);
else
  isFriend = (D->getFriendObjectKind() != Decl::FOK_None);

bool MergeWithParentScope = (TemplateParams != nullptr) ||
  !(isa<Decl>(Owner) &&
    cast<Decl>(Owner)->isDefinedOutsideFunctionOrMethod());
LocalInstantiationScope Scope(SemaRef, MergeWithParentScope);

// Instantiate enclosing template arguments for friends.
SmallVector<TemplateParameterList *, 4> TempParamLists;
unsigned NumTempParamLists = 0;
if (isFriend && (NumTempParamLists = D->getNumTemplateParameterLists())) {
  TempParamLists.resize(NumTempParamLists);
  for (unsigned I = 0; I != NumTempParamLists; ++I) {
    TemplateParameterList *TempParams = D->getTemplateParameterList(I);
    TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
    if (!InstParams)
      return nullptr;
    TempParamLists[I] = InstParams;
  }
}

ExplicitSpecifier InstantiatedExplicitSpecifier =
    instantiateExplicitSpecifier(SemaRef, TemplateArgs,
                                 ExplicitSpecifier::getFromDecl(D), D);
if (InstantiatedExplicitSpecifier.isInvalid())
  return nullptr;

// Implicit destructors/constructors created for local classes in
// DeclareImplicit* (see SemaDeclCXX.cpp) might not have an associated TSI.
// Unfortunately there isn't enough context in those functions to
// conditionally populate the TSI without breaking non-template related use
// cases. Populate TSIs prior to calling SubstFunctionType to make sure we get
// a proper transformation.
if (cast<CXXRecordDecl>(D->getParent())->isLambda() &&
    !D->getTypeSourceInfo() &&
    isa<CXXConstructorDecl, CXXDestructorDecl>(D)) {
  TypeSourceInfo *TSI =
      SemaRef.Context.getTrivialTypeSourceInfo(D->getType());
  D->setTypeSourceInfo(TSI);
}

SmallVector<ParmVarDecl *, 4> Params;
TypeSourceInfo *TInfo = SubstFunctionType(D, Params);
if (!TInfo)
  return nullptr;
QualType T = adjustFunctionTypeForInstantiation(SemaRef.Context, D, TInfo);

if (TemplateParams && TemplateParams->size()) {
  auto *LastParam =
      dyn_cast<TemplateTypeParmDecl>(TemplateParams->asArray().back());
  if (LastParam && LastParam->isImplicit() &&
      LastParam->hasTypeConstraint()) {
    // In abbreviated templates, the type-constraints of invented template
    // type parameters are instantiated with the function type, invalidating
    // the TemplateParameterList which relied on the template type parameter
    // not having a type constraint. Recreate the TemplateParameterList with
    // the updated parameter list.
    TemplateParams = TemplateParameterList::Create(
        SemaRef.Context, TemplateParams->getTemplateLoc(),
        TemplateParams->getLAngleLoc(), TemplateParams->asArray(),
        TemplateParams->getRAngleLoc(), TemplateParams->getRequiresClause());
  }
}

NestedNameSpecifierLoc QualifierLoc = D->getQualifierLoc();
if (QualifierLoc) {
  QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                               TemplateArgs);
  if (!QualifierLoc)
    return nullptr;
}

// FIXME: Concepts: Do not substitute into constraint expressions
Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
if (TrailingRequiresClause) {
  EnterExpressionEvaluationContext ConstantEvaluated(
      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
  auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(Owner);
  Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext,
                                   D->getMethodQualifiers(), ThisContext);
  ExprResult SubstRC = SemaRef.SubstExpr(TrailingRequiresClause,
                                         TemplateArgs);
  if (SubstRC.isInvalid())
    return nullptr;
  TrailingRequiresClause = SubstRC.get();
  if (!SemaRef.CheckConstraintExpression(TrailingRequiresClause))
    return nullptr;
}

DeclContext *DC = Owner;
if (isFriend) {
  if (QualifierLoc) {
    CXXScopeSpec SS;
    SS.Adopt(QualifierLoc);
    DC = SemaRef.computeDeclContext(SS);

    if (DC && SemaRef.RequireCompleteDeclContext(SS, DC))
      return nullptr;
  } else {
    DC = SemaRef.FindInstantiatedContext(D->getLocation(),
                                         D->getDeclContext(),
                                         TemplateArgs);
  }
  if (!DC) return nullptr;
}

DeclarationNameInfo NameInfo
  = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);

if (FunctionRewriteKind != RewriteKind::None)
  adjustForRewrite(FunctionRewriteKind, D, T, TInfo, NameInfo);

// Build the instantiated method declaration.
CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
CXXMethodDecl *Method = nullptr;

SourceLocation StartLoc = D->getInnerLocStart();
if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(D)) {
  Method = CXXConstructorDecl::Create(
      SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
      InstantiatedExplicitSpecifier, Constructor->isInlineSpecified(), false,
      Constructor->getConstexprKind(), InheritedConstructor(),
      TrailingRequiresClause);
  Method->setRangeEnd(Constructor->getEndLoc());
} else if (CXXDestructorDecl *Destructor = dyn_cast<CXXDestructorDecl>(D)) {
  Method = CXXDestructorDecl::Create(
      SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
      Destructor->isInlineSpecified(), false, Destructor->getConstexprKind(),
      TrailingRequiresClause);
  Method->setRangeEnd(Destructor->getEndLoc());
  Method->setDeclName(SemaRef.Context.DeclarationNames.getCXXDestructorName(
      SemaRef.Context.getCanonicalType(
          SemaRef.Context.getTypeDeclType(Record))));
} else if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(D)) {
  Method = CXXConversionDecl::Create(
      SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
      Conversion->isInlineSpecified(), InstantiatedExplicitSpecifier,
      Conversion->getConstexprKind(), Conversion->getEndLoc(),
      TrailingRequiresClause);
} else {
  StorageClass SC = D->isStatic() ? SC_Static : SC_None;
  Method = CXXMethodDecl::Create(SemaRef.Context, Record, StartLoc, NameInfo,
                                 T, TInfo, SC, D->isInlineSpecified(),
                                 D->getConstexprKind(), D->getEndLoc(),
                                 TrailingRequiresClause);
}

if (D->isInlined())
  Method->setImplicitlyInline();

if (QualifierLoc)
  Method->setQualifierInfo(QualifierLoc);

if (TemplateParams) {
  // Our resulting instantiation is actually a function template, since we
  // are substituting only the outer template parameters. For example, given
  //
  //   template<typename T>
  //   struct X {
  //     template<typename U> void f(T, U);
  //   };
  //
  //   X<int> x;
  //
  // We are instantiating the member template "f" within X<int>, which means
  // substituting int for T, but leaving "f" as a member function template.
  // Build the function template itself.
  FunctionTemplate = FunctionTemplateDecl::Create(SemaRef.Context, Record,
                                                  Method->getLocation(),
                                                  Method->getDeclName(),
                                                  TemplateParams, Method);
  if (isFriend) {
    FunctionTemplate->setLexicalDeclContext(Owner);
    FunctionTemplate->setObjectOfFriendDecl();
  } else if (D->isOutOfLine())
    FunctionTemplate->setLexicalDeclContext(D->getLexicalDeclContext());
  Method->setDescribedFunctionTemplate(FunctionTemplate);
} else if (FunctionTemplate) {
  // Record this function template specialization.
  ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
  Method->setFunctionTemplateSpecialization(FunctionTemplate,
                       TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                        Innermost),
                                            /*InsertPos=*/nullptr);
} else if (!isFriend) {
  // Record that this is an instantiation of a member function.
  Method->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
}

// If we are instantiating a member function defined
// out-of-line, the instantiation will have the same lexical
// context (which will be a namespace scope) as the template.
if (isFriend) {
  if (NumTempParamLists)
    Method->setTemplateParameterListsInfo(
        SemaRef.Context,
        llvm::makeArrayRef(TempParamLists.data(), NumTempParamLists));

  Method->setLexicalDeclContext(Owner);
  Method->setObjectOfFriendDecl();
} else if (D->isOutOfLine())
  Method->setLexicalDeclContext(D->getLexicalDeclContext());

// Attach the parameters
for (unsigned P = 0; P < Params.size(); ++P)
  Params[P]->setOwningFunction(Method);
Method->setParams(Params);

if (InitMethodInstantiation(Method, D))
  Method->setInvalidDecl();

LookupResult Previous(SemaRef, NameInfo, Sema::LookupOrdinaryName,
                      Sema::ForExternalRedeclaration);

bool IsExplicitSpecialization = false;

// If the name of this function was written as a template-id, instantiate
// the explicit template arguments.
if (DependentFunctionTemplateSpecializationInfo *Info
      = D->getDependentSpecializationInfo()) {
  assert(isFriend && "non-friend has dependent specialization info?")((void)0);

  // Instantiate the explicit template arguments.
  TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                        Info->getRAngleLoc());
  if (SemaRef.Subst(Info->getTemplateArgs(), Info->getNumTemplateArgs(),
                    ExplicitArgs, TemplateArgs))
    return nullptr;

  // Map the candidate templates to their instantiations.
  for (unsigned I = 0, E = Info->getNumTemplates(); I != E; ++I) {
    Decl *Temp = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                              Info->getTemplate(I),
                                              TemplateArgs);
    if (!Temp) return nullptr;

    Previous.addDecl(cast<FunctionTemplateDecl>(Temp));
  }

  if (SemaRef.CheckFunctionTemplateSpecialization(Method,
                                                  &ExplicitArgs,
                                                  Previous))
    Method->setInvalidDecl();

  IsExplicitSpecialization = true;
} else if (const ASTTemplateArgumentListInfo *Info =
               ClassScopeSpecializationArgs.getValueOr(
                   D->getTemplateSpecializationArgsAsWritten())) {
  SemaRef.LookupQualifiedName(Previous, DC);

  TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                        Info->getRAngleLoc());
  if (SemaRef.Subst(Info->getTemplateArgs(), Info->getNumTemplateArgs(),
                    ExplicitArgs, TemplateArgs))
    return nullptr;

  if (SemaRef.CheckFunctionTemplateSpecialization(Method,
                                                  &ExplicitArgs,
                                                  Previous))
    Method->setInvalidDecl();

  IsExplicitSpecialization = true;
} else if (ClassScopeSpecializationArgs) {
  // Class-scope explicit specialization written without explicit template
  // arguments.
  SemaRef.LookupQualifiedName(Previous, DC);
  if (SemaRef.CheckFunctionTemplateSpecialization(Method, nullptr, Previous))
    Method->setInvalidDecl();

  IsExplicitSpecialization = true;
} else if (!FunctionTemplate || TemplateParams || isFriend) {
  SemaRef.LookupQualifiedName(Previous, Record);

  // In C++, the previous declaration we find might be a tag type
  // (class or enum). In this case, the new declaration will hide the
  // tag type. Note that this does does not apply if we're declaring a
  // typedef (C++ [dcl.typedef]p4).
  if (Previous.isSingleTagDecl())
    Previous.clear();
}

SemaRef.CheckFunctionDeclaration(nullptr, Method, Previous,
                                 IsExplicitSpecialization);

if (D->isPure())
  SemaRef.CheckPureMethod(Method, SourceRange());

// Propagate access.  For a non-friend declaration, the access is
// whatever we're propagating from.  For a friend, it should be the
// previous declaration we just found.
if (isFriend && Method->getPreviousDecl())
  Method->setAccess(Method->getPreviousDecl()->getAccess());
else
  Method->setAccess(D->getAccess());
if (FunctionTemplate)
  FunctionTemplate->setAccess(Method->getAccess());

SemaRef.CheckOverrideControl(Method);

// If a function is defined as defaulted or deleted, mark it as such now.
if (D->isExplicitlyDefaulted()) {
  if (SubstDefaultedFunction(Method, D))
    return nullptr;
}
if (D->isDeletedAsWritten())
  SemaRef.SetDeclDeleted(Method, Method->getLocation());

// If this is an explicit specialization, mark the implicitly-instantiated
// template specialization as being an explicit specialization too.
// FIXME: Is this necessary?
if (IsExplicitSpecialization && !isFriend)
  SemaRef.CompleteMemberSpecialization(Method, Previous);

// If there's a function template, let our caller handle it.
if (FunctionTemplate) {
  // do nothing

// Don't hide a (potentially) valid declaration with an invalid one.
} else if (Method->isInvalidDecl() && !Previous.empty()) {
  // do nothing

// Otherwise, check access to friends and make them visible.
} else if (isFriend) {
  // We only need to re-check access for methods which we didn't
  // manage to match during parsing.
  if (!D->getPreviousDecl())
    SemaRef.CheckFriendAccess(Method);

  Record->makeDeclVisibleInContext(Method);

// Otherwise, add the declaration.  We don't need to do this for
// class-scope specializations because we'll have matched them with
// the appropriate template.
} else {
  Owner->addDecl(Method);
}

// PR17480: Honor the used attribute to instantiate member function
// definitions
if (Method->hasAttr<UsedAttr>()) {
  if (const auto *A = dyn_cast<CXXRecordDecl>(Owner)) {
    SourceLocation Loc;
    if (const MemberSpecializationInfo *MSInfo =
            A->getMemberSpecializationInfo())
      Loc = MSInfo->getPointOfInstantiation();
    else if (const auto *Spec = dyn_cast<ClassTemplateSpecializationDecl>(A))
      Loc = Spec->getPointOfInstantiation();
    SemaRef.MarkFunctionReferenced(Loc, Method);
  }
}

return Method;
2642}

2644Decl *TemplateDeclInstantiator::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
return VisitCXXMethodDecl(D);
2646}

2648Decl *TemplateDeclInstantiator::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
return VisitCXXMethodDecl(D);
2650}

2652Decl *TemplateDeclInstantiator::VisitCXXConversionDecl(CXXConversionDecl *D) {
return VisitCXXMethodDecl(D);
2654}

2656Decl *TemplateDeclInstantiator::VisitParmVarDecl(ParmVarDecl *D) {
return SemaRef.SubstParmVarDecl(D, TemplateArgs, /*indexAdjustment*/ 0, None,
                                /*ExpectParameterPack=*/ false);
2659}

2661Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
                                                  TemplateTypeParmDecl *D) {
assert(D->getTypeForDecl()->isTemplateTypeParmType())((void)0);

Optional<unsigned> NumExpanded;

if (const TypeConstraint *TC = D->getTypeConstraint()) {
  if (D->isPackExpansion() && !D->isExpandedParameterPack()) {
    assert(TC->getTemplateArgsAsWritten() &&((void)0)
           "type parameter can only be an expansion when explicit arguments "((void)0)
           "are specified")((void)0);
    // The template type parameter pack's type is a pack expansion of types.
    // Determine whether we need to expand this parameter pack into separate
    // types.
    SmallVector<UnexpandedParameterPack, 2> Unexpanded;
    for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
      SemaRef.collectUnexpandedParameterPacks(ArgLoc, Unexpanded);

    // Determine whether the set of unexpanded parameter packs can and should
    // be expanded.
    bool Expand = true;
    bool RetainExpansion = false;
    if (SemaRef.CheckParameterPacksForExpansion(
            cast<CXXFoldExpr>(TC->getImmediatelyDeclaredConstraint())
                ->getEllipsisLoc(),
            SourceRange(TC->getConceptNameLoc(),
                        TC->hasExplicitTemplateArgs() ?
                        TC->getTemplateArgsAsWritten()->getRAngleLoc() :
                        TC->getConceptNameInfo().getEndLoc()),
            Unexpanded, TemplateArgs, Expand, RetainExpansion, NumExpanded))
      return nullptr;
  }
}

TemplateTypeParmDecl *Inst = TemplateTypeParmDecl::Create(
    SemaRef.Context, Owner, D->getBeginLoc(), D->getLocation(),
    D->getDepth() - TemplateArgs.getNumSubstitutedLevels(), D->getIndex(),
    D->getIdentifier(), D->wasDeclaredWithTypename(), D->isParameterPack(),
    D->hasTypeConstraint(), NumExpanded);

Inst->setAccess(AS_public);
Inst->setImplicit(D->isImplicit());
if (auto *TC = D->getTypeConstraint()) {
  if (!D->isImplicit()) {
    // Invented template parameter type constraints will be instantiated with
    // the corresponding auto-typed parameter as it might reference other
    // parameters.

    // TODO: Concepts: do not instantiate the constraint (delayed constraint
    // substitution)
    const ASTTemplateArgumentListInfo *TemplArgInfo
      = TC->getTemplateArgsAsWritten();
    TemplateArgumentListInfo InstArgs;

    if (TemplArgInfo) {
      InstArgs.setLAngleLoc(TemplArgInfo->LAngleLoc);
      InstArgs.setRAngleLoc(TemplArgInfo->RAngleLoc);
      if (SemaRef.Subst(TemplArgInfo->getTemplateArgs(),
                        TemplArgInfo->NumTemplateArgs,
                        InstArgs, TemplateArgs))
        return nullptr;
    }
    if (SemaRef.AttachTypeConstraint(
            TC->getNestedNameSpecifierLoc(), TC->getConceptNameInfo(),
            TC->getNamedConcept(), &InstArgs, Inst,
            D->isParameterPack()
                ? cast<CXXFoldExpr>(TC->getImmediatelyDeclaredConstraint())
                    ->getEllipsisLoc()
                : SourceLocation()))
      return nullptr;
  }
}
if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
  TypeSourceInfo *InstantiatedDefaultArg =
      SemaRef.SubstType(D->getDefaultArgumentInfo(), TemplateArgs,
                        D->getDefaultArgumentLoc(), D->getDeclName());
  if (InstantiatedDefaultArg)
    Inst->setDefaultArgument(InstantiatedDefaultArg);
}

// Introduce this template parameter's instantiation into the instantiation
// scope.
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Inst);

return Inst;
2746}

2748Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
                                               NonTypeTemplateParmDecl *D) {
// Substitute into the type of the non-type template parameter.
TypeLoc TL = D->getTypeSourceInfo()->getTypeLoc();
SmallVector<TypeSourceInfo *, 4> ExpandedParameterPackTypesAsWritten;
SmallVector<QualType, 4> ExpandedParameterPackTypes;
bool IsExpandedParameterPack = false;
TypeSourceInfo *DI;
QualType T;
bool Invalid = false;

if (D->isExpandedParameterPack()) {
  // The non-type template parameter pack is an already-expanded pack
  // expansion of types. Substitute into each of the expanded types.
  ExpandedParameterPackTypes.reserve(D->getNumExpansionTypes());
  ExpandedParameterPackTypesAsWritten.reserve(D->getNumExpansionTypes());
  for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
    TypeSourceInfo *NewDI =
        SemaRef.SubstType(D->getExpansionTypeSourceInfo(I), TemplateArgs,
                          D->getLocation(), D->getDeclName());
    if (!NewDI)
      return nullptr;

    QualType NewT =
        SemaRef.CheckNonTypeTemplateParameterType(NewDI, D->getLocation());
    if (NewT.isNull())
      return nullptr;

    ExpandedParameterPackTypesAsWritten.push_back(NewDI);
    ExpandedParameterPackTypes.push_back(NewT);
  }

  IsExpandedParameterPack = true;
  DI = D->getTypeSourceInfo();
  T = DI->getType();
} else if (D->isPackExpansion()) {
  // The non-type template parameter pack's type is a pack expansion of types.
  // Determine whether we need to expand this parameter pack into separate
  // types.
  PackExpansionTypeLoc Expansion = TL.castAs<PackExpansionTypeLoc>();
  TypeLoc Pattern = Expansion.getPatternLoc();
  SmallVector<UnexpandedParameterPack, 2> Unexpanded;
  SemaRef.collectUnexpandedParameterPacks(Pattern, Unexpanded);

  // Determine whether the set of unexpanded parameter packs can and should
  // be expanded.
  bool Expand = true;
  bool RetainExpansion = false;
  Optional<unsigned> OrigNumExpansions
    = Expansion.getTypePtr()->getNumExpansions();
  Optional<unsigned> NumExpansions = OrigNumExpansions;
  if (SemaRef.CheckParameterPacksForExpansion(Expansion.getEllipsisLoc(),
                                              Pattern.getSourceRange(),
                                              Unexpanded,
                                              TemplateArgs,
                                              Expand, RetainExpansion,
                                              NumExpansions))
    return nullptr;

  if (Expand) {
    for (unsigned I = 0; I != *NumExpansions; ++I) {
      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
      TypeSourceInfo *NewDI = SemaRef.SubstType(Pattern, TemplateArgs,
                                                D->getLocation(),
                                                D->getDeclName());
      if (!NewDI)
        return nullptr;

      QualType NewT =
          SemaRef.CheckNonTypeTemplateParameterType(NewDI, D->getLocation());
      if (NewT.isNull())
        return nullptr;

      ExpandedParameterPackTypesAsWritten.push_back(NewDI);
      ExpandedParameterPackTypes.push_back(NewT);
    }

    // Note that we have an expanded parameter pack. The "type" of this
    // expanded parameter pack is the original expansion type, but callers
    // will end up using the expanded parameter pack types for type-checking.
    IsExpandedParameterPack = true;
    DI = D->getTypeSourceInfo();
    T = DI->getType();
  } else {
    // We cannot fully expand the pack expansion now, so substitute into the
    // pattern and create a new pack expansion type.
    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
    TypeSourceInfo *NewPattern = SemaRef.SubstType(Pattern, TemplateArgs,
                                                   D->getLocation(),
                                                   D->getDeclName());
    if (!NewPattern)
      return nullptr;

    SemaRef.CheckNonTypeTemplateParameterType(NewPattern, D->getLocation());
    DI = SemaRef.CheckPackExpansion(NewPattern, Expansion.getEllipsisLoc(),
                                    NumExpansions);
    if (!DI)
      return nullptr;

    T = DI->getType();
  }
} else {
  // Simple case: substitution into a parameter that is not a parameter pack.
  DI = SemaRef.SubstType(D->getTypeSourceInfo(), TemplateArgs,
                         D->getLocation(), D->getDeclName());
  if (!DI)
    return nullptr;

  // Check that this type is acceptable for a non-type template parameter.
  T = SemaRef.CheckNonTypeTemplateParameterType(DI, D->getLocation());
  if (T.isNull()) {
    T = SemaRef.Context.IntTy;
    Invalid = true;
  }
}

NonTypeTemplateParmDecl *Param;
if (IsExpandedParameterPack)
  Param = NonTypeTemplateParmDecl::Create(
      SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
      D->getPosition(), D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
      ExpandedParameterPackTypesAsWritten);
else
  Param = NonTypeTemplateParmDecl::Create(
      SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
      D->getPosition(), D->getIdentifier(), T, D->isParameterPack(), DI);

if (AutoTypeLoc AutoLoc = DI->getTypeLoc().getContainedAutoTypeLoc())
  if (AutoLoc.isConstrained())
    if (SemaRef.AttachTypeConstraint(
            AutoLoc, Param,
            IsExpandedParameterPack
              ? DI->getTypeLoc().getAs<PackExpansionTypeLoc>()
                  .getEllipsisLoc()
              : SourceLocation()))
      Invalid = true;

Param->setAccess(AS_public);
Param->setImplicit(D->isImplicit());
if (Invalid)
  Param->setInvalidDecl();

if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
  EnterExpressionEvaluationContext ConstantEvaluated(
      SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
  ExprResult Value = SemaRef.SubstExpr(D->getDefaultArgument(), TemplateArgs);
  if (!Value.isInvalid())
    Param->setDefaultArgument(Value.get());
}

// Introduce this template parameter's instantiation into the instantiation
// scope.
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
return Param;
2904}

2906static void collectUnexpandedParameterPacks(
  Sema &S,
  TemplateParameterList *Params,
  SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
for (const auto &P : *Params) {
  if (P->isTemplateParameterPack())
    continue;
  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P))
    S.collectUnexpandedParameterPacks(NTTP->getTypeSourceInfo()->getTypeLoc(),
                                      Unexpanded);
  if (TemplateTemplateParmDecl *TTP = dyn_cast<TemplateTemplateParmDecl>(P))
    collectUnexpandedParameterPacks(S, TTP->getTemplateParameters(),
                                    Unexpanded);
}
2920}

2922Decl *
2923TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
                                                TemplateTemplateParmDecl *D) {
// Instantiate the template parameter list of the template template parameter.
TemplateParameterList *TempParams = D->getTemplateParameters();
TemplateParameterList *InstParams;
SmallVector<TemplateParameterList*, 8> ExpandedParams;

bool IsExpandedParameterPack = false;

if (D->isExpandedParameterPack()) {
  // The template template parameter pack is an already-expanded pack
  // expansion of template parameters. Substitute into each of the expanded
  // parameters.
  ExpandedParams.reserve(D->getNumExpansionTemplateParameters());
  for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
       I != N; ++I) {
    LocalInstantiationScope Scope(SemaRef);
    TemplateParameterList *Expansion =
      SubstTemplateParams(D->getExpansionTemplateParameters(I));
    if (!Expansion)
      return nullptr;
    ExpandedParams.push_back(Expansion);
  }

  IsExpandedParameterPack = true;
  InstParams = TempParams;
} else if (D->isPackExpansion()) {
  // The template template parameter pack expands to a pack of template
  // template parameters. Determine whether we need to expand this parameter
  // pack into separate parameters.
  SmallVector<UnexpandedParameterPack, 2> Unexpanded;
  collectUnexpandedParameterPacks(SemaRef, D->getTemplateParameters(),
                                  Unexpanded);

  // Determine whether the set of unexpanded parameter packs can and should
  // be expanded.
  bool Expand = true;
  bool RetainExpansion = false;
  Optional<unsigned> NumExpansions;
  if (SemaRef.CheckParameterPacksForExpansion(D->getLocation(),
                                              TempParams->getSourceRange(),
                                              Unexpanded,
                                              TemplateArgs,
                                              Expand, RetainExpansion,
                                              NumExpansions))
    return nullptr;

  if (Expand) {
    for (unsigned I = 0; I != *NumExpansions; ++I) {
      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
      LocalInstantiationScope Scope(SemaRef);
      TemplateParameterList *Expansion = SubstTemplateParams(TempParams);
      if (!Expansion)
        return nullptr;
      ExpandedParams.push_back(Expansion);
    }

    // Note that we have an expanded parameter pack. The "type" of this
    // expanded parameter pack is the original expansion type, but callers
    // will end up using the expanded parameter pack types for type-checking.
    IsExpandedParameterPack = true;
    InstParams = TempParams;
  } else {
    // We cannot fully expand the pack expansion now, so just substitute
    // into the pattern.
    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);

    LocalInstantiationScope Scope(SemaRef);
    InstParams = SubstTemplateParams(TempParams);
    if (!InstParams)
      return nullptr;
  }
} else {
  // Perform the actual substitution of template parameters within a new,
  // local instantiation scope.
  LocalInstantiationScope Scope(SemaRef);
  InstParams = SubstTemplateParams(TempParams);
  if (!InstParams)
    return nullptr;
}

// Build the template template parameter.
TemplateTemplateParmDecl *Param;
if (IsExpandedParameterPack)
  Param = TemplateTemplateParmDecl::Create(
      SemaRef.Context, Owner, D->getLocation(),
      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
      D->getPosition(), D->getIdentifier(), InstParams, ExpandedParams);
else
  Param = TemplateTemplateParmDecl::Create(
      SemaRef.Context, Owner, D->getLocation(),
      D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
      D->getPosition(), D->isParameterPack(), D->getIdentifier(), InstParams);
if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
  NestedNameSpecifierLoc QualifierLoc =
      D->getDefaultArgument().getTemplateQualifierLoc();
  QualifierLoc =
      SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgs);
  TemplateName TName = SemaRef.SubstTemplateName(
      QualifierLoc, D->getDefaultArgument().getArgument().getAsTemplate(),
      D->getDefaultArgument().getTemplateNameLoc(), TemplateArgs);
  if (!TName.isNull())
    Param->setDefaultArgument(
        SemaRef.Context,
        TemplateArgumentLoc(SemaRef.Context, TemplateArgument(TName),
                            D->getDefaultArgument().getTemplateQualifierLoc(),
                            D->getDefaultArgument().getTemplateNameLoc()));
}
Param->setAccess(AS_public);
Param->setImplicit(D->isImplicit());

// Introduce this template parameter's instantiation into the instantiation
// scope.
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);

return Param;
3039}

3041Decl *TemplateDeclInstantiator::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
// Using directives are never dependent (and never contain any types or
// expressions), so they require no explicit instantiation work.

UsingDirectiveDecl *Inst
  = UsingDirectiveDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                               D->getNamespaceKeyLocation(),
                               D->getQualifierLoc(),
                               D->getIdentLocation(),
                               D->getNominatedNamespace(),
                               D->getCommonAncestor());

// Add the using directive to its declaration context
// only if this is not a function or method.
if (!Owner->isFunctionOrMethod())
  Owner->addDecl(Inst);

return Inst;
3059}

3061Decl *TemplateDeclInstantiator::VisitBaseUsingDecls(BaseUsingDecl *D,
                                                  BaseUsingDecl *Inst,
                                                  LookupResult *Lookup) {

bool isFunctionScope = Owner->isFunctionOrMethod();

for (auto *Shadow : D->shadows()) {
  // FIXME: UsingShadowDecl doesn't preserve its immediate target, so
  // reconstruct it in the case where it matters. Hm, can we extract it from
  // the DeclSpec when parsing and save it in the UsingDecl itself?
  NamedDecl *OldTarget = Shadow->getTargetDecl();
  if (auto *CUSD = dyn_cast<ConstructorUsingShadowDecl>(Shadow))
    if (auto *BaseShadow = CUSD->getNominatedBaseClassShadowDecl())
      OldTarget = BaseShadow;

  NamedDecl *InstTarget = nullptr;
  if (auto *EmptyD =
          dyn_cast<UnresolvedUsingIfExistsDecl>(Shadow->getTargetDecl())) {
    InstTarget = UnresolvedUsingIfExistsDecl::Create(
        SemaRef.Context, Owner, EmptyD->getLocation(), EmptyD->getDeclName());
  } else {
    InstTarget = cast_or_null<NamedDecl>(SemaRef.FindInstantiatedDecl(
        Shadow->getLocation(), OldTarget, TemplateArgs));
  }
  if (!InstTarget)
    return nullptr;

  UsingShadowDecl *PrevDecl = nullptr;
  if (Lookup &&
      SemaRef.CheckUsingShadowDecl(Inst, InstTarget, *Lookup, PrevDecl))
    continue;

  if (UsingShadowDecl *OldPrev = getPreviousDeclForInstantiation(Shadow))
    PrevDecl = cast_or_null<UsingShadowDecl>(SemaRef.FindInstantiatedDecl(
        Shadow->getLocation(), OldPrev, TemplateArgs));

  UsingShadowDecl *InstShadow = SemaRef.BuildUsingShadowDecl(
      /*Scope*/ nullptr, Inst, InstTarget, PrevDecl);
  SemaRef.Context.setInstantiatedFromUsingShadowDecl(InstShadow, Shadow);

  if (isFunctionScope)
    SemaRef.CurrentInstantiationScope->InstantiatedLocal(Shadow, InstShadow);
}

return Inst;
3106}

3108Decl *TemplateDeclInstantiator::VisitUsingDecl(UsingDecl *D) {

// The nested name specifier may be dependent, for example
//     template <typename T> struct t {
//       struct s1 { T f1(); };
//       struct s2 : s1 { using s1::f1; };
//     };
//     template struct t<int>;
// Here, in using s1::f1, s1 refers to t<T>::s1;
// we need to substitute for t<int>::s1.
NestedNameSpecifierLoc QualifierLoc
  = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(),
                                        TemplateArgs);
if (!QualifierLoc)
  return nullptr;

// For an inheriting constructor declaration, the name of the using
// declaration is the name of a constructor in this class, not in the
// base class.
DeclarationNameInfo NameInfo = D->getNameInfo();
if (NameInfo.getName().getNameKind() == DeclarationName::CXXConstructorName)
  if (auto *RD = dyn_cast<CXXRecordDecl>(SemaRef.CurContext))
    NameInfo.setName(SemaRef.Context.DeclarationNames.getCXXConstructorName(
        SemaRef.Context.getCanonicalType(SemaRef.Context.getRecordType(RD))));

// We only need to do redeclaration lookups if we're in a class scope (in
// fact, it's not really even possible in non-class scopes).
bool CheckRedeclaration = Owner->isRecord();
LookupResult Prev(SemaRef, NameInfo, Sema::LookupUsingDeclName,
                  Sema::ForVisibleRedeclaration);

UsingDecl *NewUD = UsingDecl::Create(SemaRef.Context, Owner,
                                     D->getUsingLoc(),
                                     QualifierLoc,
                                     NameInfo,
                                     D->hasTypename());

CXXScopeSpec SS;
SS.Adopt(QualifierLoc);
if (CheckRedeclaration) {
  Prev.setHideTags(false);
  SemaRef.LookupQualifiedName(Prev, Owner);

  // Check for invalid redeclarations.
  if (SemaRef.CheckUsingDeclRedeclaration(D->getUsingLoc(),
                                          D->hasTypename(), SS,
                                          D->getLocation(), Prev))
    NewUD->setInvalidDecl();
}

if (!NewUD->isInvalidDecl() &&
    SemaRef.CheckUsingDeclQualifier(D->getUsingLoc(), D->hasTypename(), SS,
                                    NameInfo, D->getLocation(), nullptr, D))
  NewUD->setInvalidDecl();

SemaRef.Context.setInstantiatedFromUsingDecl(NewUD, D);
NewUD->setAccess(D->getAccess());
Owner->addDecl(NewUD);

// Don't process the shadow decls for an invalid decl.
if (NewUD->isInvalidDecl())
  return NewUD;

// If the using scope was dependent, or we had dependent bases, we need to
// recheck the inheritance
if (NameInfo.getName().getNameKind() == DeclarationName::CXXConstructorName)
  SemaRef.CheckInheritingConstructorUsingDecl(NewUD);

return VisitBaseUsingDecls(D, NewUD, CheckRedeclaration ? &Prev : nullptr);
3177}

3179Decl *TemplateDeclInstantiator::VisitUsingEnumDecl(UsingEnumDecl *D) {
// Cannot be a dependent type, but still could be an instantiation
EnumDecl *EnumD = cast_or_null<EnumDecl>(SemaRef.FindInstantiatedDecl(
    D->getLocation(), D->getEnumDecl(), TemplateArgs));

if (SemaRef.RequireCompleteEnumDecl(EnumD, EnumD->getLocation()))
  return nullptr;

UsingEnumDecl *NewUD =
    UsingEnumDecl::Create(SemaRef.Context, Owner, D->getUsingLoc(),
                          D->getEnumLoc(), D->getLocation(), EnumD);

SemaRef.Context.setInstantiatedFromUsingEnumDecl(NewUD, D);
NewUD->setAccess(D->getAccess());
Owner->addDecl(NewUD);

// Don't process the shadow decls for an invalid decl.
if (NewUD->isInvalidDecl())
  return NewUD;

// We don't have to recheck for duplication of the UsingEnumDecl itself, as it
// cannot be dependent, and will therefore have been checked during template
// definition.

return VisitBaseUsingDecls(D, NewUD, nullptr);
3204}

3206Decl *TemplateDeclInstantiator::VisitUsingShadowDecl(UsingShadowDecl *D) {
// Ignore these;  we handle them in bulk when processing the UsingDecl.
return nullptr;
3209}

3211Decl *TemplateDeclInstantiator::VisitConstructorUsingShadowDecl(
  ConstructorUsingShadowDecl *D) {
// Ignore these;  we handle them in bulk when processing the UsingDecl.
return nullptr;
3215}

3217template <typename T>
3218Decl *TemplateDeclInstantiator::instantiateUnresolvedUsingDecl(
  T *D, bool InstantiatingPackElement) {
// If this is a pack expansion, expand it now.
if (D->isPackExpansion() && !InstantiatingPackElement) {
  SmallVector<UnexpandedParameterPack, 2> Unexpanded;
  SemaRef.collectUnexpandedParameterPacks(D->getQualifierLoc(), Unexpanded);
  SemaRef.collectUnexpandedParameterPacks(D->getNameInfo(), Unexpanded);

  // Determine whether the set of unexpanded parameter packs can and should
  // be expanded.
  bool Expand = true;
  bool RetainExpansion = false;
  Optional<unsigned> NumExpansions;
  if (SemaRef.CheckParameterPacksForExpansion(
        D->getEllipsisLoc(), D->getSourceRange(), Unexpanded, TemplateArgs,
          Expand, RetainExpansion, NumExpansions))
    return nullptr;

  // This declaration cannot appear within a function template signature,
  // so we can't have a partial argument list for a parameter pack.
  assert(!RetainExpansion &&((void)0)
         "should never need to retain an expansion for UsingPackDecl")((void)0);

  if (!Expand) {
    // We cannot fully expand the pack expansion now, so substitute into the
    // pattern and create a new pack expansion.
    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
    return instantiateUnresolvedUsingDecl(D, true);
  }

  // Within a function, we don't have any normal way to check for conflicts
  // between shadow declarations from different using declarations in the
  // same pack expansion, but this is always ill-formed because all expansions
  // must produce (conflicting) enumerators.
  //
  // Sadly we can't just reject this in the template definition because it
  // could be valid if the pack is empty or has exactly one expansion.
  if (D->getDeclContext()->isFunctionOrMethod() && *NumExpansions > 1) {
    SemaRef.Diag(D->getEllipsisLoc(),
                 diag::err_using_decl_redeclaration_expansion);
    return nullptr;
  }

  // Instantiate the slices of this pack and build a UsingPackDecl.
  SmallVector<NamedDecl*, 8> Expansions;
  for (unsigned I = 0; I != *NumExpansions; ++I) {
    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
    Decl *Slice = instantiateUnresolvedUsingDecl(D, true);
    if (!Slice)
      return nullptr;
    // Note that we can still get unresolved using declarations here, if we
    // had arguments for all packs but the pattern also contained other
    // template arguments (this only happens during partial substitution, eg
    // into the body of a generic lambda in a function template).
    Expansions.push_back(cast<NamedDecl>(Slice));
  }

  auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
  if (isDeclWithinFunction(D))
    SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
  return NewD;
}

UnresolvedUsingTypenameDecl *TD = dyn_cast<UnresolvedUsingTypenameDecl>(D);
SourceLocation TypenameLoc = TD ? TD->getTypenameLoc() : SourceLocation();

NestedNameSpecifierLoc QualifierLoc
  = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(),
                                        TemplateArgs);
if (!QualifierLoc)
  return nullptr;

CXXScopeSpec SS;
SS.Adopt(QualifierLoc);

DeclarationNameInfo NameInfo
  = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);

// Produce a pack expansion only if we're not instantiating a particular
// slice of a pack expansion.
bool InstantiatingSlice = D->getEllipsisLoc().isValid() &&
                          SemaRef.ArgumentPackSubstitutionIndex != -1;
SourceLocation EllipsisLoc =
    InstantiatingSlice ? SourceLocation() : D->getEllipsisLoc();

bool IsUsingIfExists = D->template hasAttr<UsingIfExistsAttr>();
NamedDecl *UD = SemaRef.BuildUsingDeclaration(
    /*Scope*/ nullptr, D->getAccess(), D->getUsingLoc(),
    /*HasTypename*/ TD, TypenameLoc, SS, NameInfo, EllipsisLoc,
    ParsedAttributesView(),
    /*IsInstantiation*/ true, IsUsingIfExists);
if (UD) {
  SemaRef.InstantiateAttrs(TemplateArgs, D, UD);
  SemaRef.Context.setInstantiatedFromUsingDecl(UD, D);
}

return UD;
3315}

3317Decl *TemplateDeclInstantiator::VisitUnresolvedUsingTypenameDecl(
  UnresolvedUsingTypenameDecl *D) {
return instantiateUnresolvedUsingDecl(D);
3320}

3322Decl *TemplateDeclInstantiator::VisitUnresolvedUsingValueDecl(
  UnresolvedUsingValueDecl *D) {
return instantiateUnresolvedUsingDecl(D);
3325}

3327Decl *TemplateDeclInstantiator::VisitUnresolvedUsingIfExistsDecl(
  UnresolvedUsingIfExistsDecl *D) {
llvm_unreachable("referring to unresolved decl out of UsingShadowDecl")__builtin_unreachable();
3330}

3332Decl *TemplateDeclInstantiator::VisitUsingPackDecl(UsingPackDecl *D) {
SmallVector<NamedDecl*, 8> Expansions;
for (auto *UD : D->expansions()) {
  if (NamedDecl *NewUD =
          SemaRef.FindInstantiatedDecl(D->getLocation(), UD, TemplateArgs))
    Expansions.push_back(NewUD);
  else
    return nullptr;
}

auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
if (isDeclWithinFunction(D))
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
return NewD;
3346}

3348Decl *TemplateDeclInstantiator::VisitClassScopeFunctionSpecializationDecl(
  ClassScopeFunctionSpecializationDecl *Decl) {
CXXMethodDecl *OldFD = Decl->getSpecialization();
return cast_or_null<CXXMethodDecl>(
    VisitCXXMethodDecl(OldFD, nullptr, Decl->getTemplateArgsAsWritten()));
3353}

3355Decl *TemplateDeclInstantiator::VisitOMPThreadPrivateDecl(
                                   OMPThreadPrivateDecl *D) {
SmallVector<Expr *, 5> Vars;
for (auto *I : D->varlists()) {
  Expr *Var = SemaRef.SubstExpr(I, TemplateArgs).get();
  assert(isa<DeclRefExpr>(Var) && "threadprivate arg is not a DeclRefExpr")((void)0);
  Vars.push_back(Var);
}

OMPThreadPrivateDecl *TD =
  SemaRef.CheckOMPThreadPrivateDecl(D->getLocation(), Vars);

TD->setAccess(AS_public);
Owner->addDecl(TD);

return TD;
3371}

3373Decl *TemplateDeclInstantiator::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
SmallVector<Expr *, 5> Vars;
for (auto *I : D->varlists()) {
  Expr *Var = SemaRef.SubstExpr(I, TemplateArgs).get();
  assert(isa<DeclRefExpr>(Var) && "allocate arg is not a DeclRefExpr")((void)0);
  Vars.push_back(Var);
}
SmallVector<OMPClause *, 4> Clauses;
// Copy map clauses from the original mapper.
for (OMPClause *C : D->clauselists()) {
  auto *AC = cast<OMPAllocatorClause>(C);
  ExprResult NewE = SemaRef.SubstExpr(AC->getAllocator(), TemplateArgs);
  if (!NewE.isUsable())
    continue;
  OMPClause *IC = SemaRef.ActOnOpenMPAllocatorClause(
      NewE.get(), AC->getBeginLoc(), AC->getLParenLoc(), AC->getEndLoc());
  Clauses.push_back(IC);
}

Sema::DeclGroupPtrTy Res = SemaRef.ActOnOpenMPAllocateDirective(
    D->getLocation(), Vars, Clauses, Owner);
if (Res.get().isNull())
  return nullptr;
return Res.get().getSingleDecl();
3397}

3399Decl *TemplateDeclInstantiator::VisitOMPRequiresDecl(OMPRequiresDecl *D) {
llvm_unreachable(__builtin_unreachable()
    "Requires directive cannot be instantiated within a dependent context")__builtin_unreachable();
3402}

3404Decl *TemplateDeclInstantiator::VisitOMPDeclareReductionDecl(
  OMPDeclareReductionDecl *D) {
// Instantiate type and check if it is allowed.
const bool RequiresInstantiation =
    D->getType()->isDependentType() ||
    D->getType()->isInstantiationDependentType() ||
    D->getType()->containsUnexpandedParameterPack();
QualType SubstReductionType;
if (RequiresInstantiation) {
  SubstReductionType = SemaRef.ActOnOpenMPDeclareReductionType(
      D->getLocation(),
      ParsedType::make(SemaRef.SubstType(
          D->getType(), TemplateArgs, D->getLocation(), DeclarationName())));
} else {
  SubstReductionType = D->getType();
}
if (SubstReductionType.isNull())
  return nullptr;
Expr *Combiner = D->getCombiner();
Expr *Init = D->getInitializer();
bool IsCorrect = true;
// Create instantiated copy.
std::pair<QualType, SourceLocation> ReductionTypes[] = {
    std::make_pair(SubstReductionType, D->getLocation())};
auto *PrevDeclInScope = D->getPrevDeclInScope();
if (PrevDeclInScope && !PrevDeclInScope->isInvalidDecl()) {
  PrevDeclInScope = cast<OMPDeclareReductionDecl>(
      SemaRef.CurrentInstantiationScope->findInstantiationOf(PrevDeclInScope)
          ->get<Decl *>());
}
auto DRD = SemaRef.ActOnOpenMPDeclareReductionDirectiveStart(
    /*S=*/nullptr, Owner, D->getDeclName(), ReductionTypes, D->getAccess(),
    PrevDeclInScope);
auto *NewDRD = cast<OMPDeclareReductionDecl>(DRD.get().getSingleDecl());
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewDRD);
Expr *SubstCombiner = nullptr;
Expr *SubstInitializer = nullptr;
// Combiners instantiation sequence.
if (Combiner) {
  SemaRef.ActOnOpenMPDeclareReductionCombinerStart(
      /*S=*/nullptr, NewDRD);
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(
      cast<DeclRefExpr>(D->getCombinerIn())->getDecl(),
      cast<DeclRefExpr>(NewDRD->getCombinerIn())->getDecl());
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(
      cast<DeclRefExpr>(D->getCombinerOut())->getDecl(),
      cast<DeclRefExpr>(NewDRD->getCombinerOut())->getDecl());
  auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(Owner);
  Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext, Qualifiers(),
                                   ThisContext);
  SubstCombiner = SemaRef.SubstExpr(Combiner, TemplateArgs).get();
  SemaRef.ActOnOpenMPDeclareReductionCombinerEnd(NewDRD, SubstCombiner);
}
// Initializers instantiation sequence.
if (Init) {
  VarDecl *OmpPrivParm = SemaRef.ActOnOpenMPDeclareReductionInitializerStart(
      /*S=*/nullptr, NewDRD);
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(
      cast<DeclRefExpr>(D->getInitOrig())->getDecl(),
      cast<DeclRefExpr>(NewDRD->getInitOrig())->getDecl());
  SemaRef.CurrentInstantiationScope->InstantiatedLocal(
      cast<DeclRefExpr>(D->getInitPriv())->getDecl(),
      cast<DeclRefExpr>(NewDRD->getInitPriv())->getDecl());
  if (D->getInitializerKind() == OMPDeclareReductionDecl::CallInit) {
    SubstInitializer = SemaRef.SubstExpr(Init, TemplateArgs).get();
  } else {
    auto *OldPrivParm =
        cast<VarDecl>(cast<DeclRefExpr>(D->getInitPriv())->getDecl());
    IsCorrect = IsCorrect && OldPrivParm->hasInit();
    if (IsCorrect)
      SemaRef.InstantiateVariableInitializer(OmpPrivParm, OldPrivParm,
                                             TemplateArgs);
  }
  SemaRef.ActOnOpenMPDeclareReductionInitializerEnd(NewDRD, SubstInitializer,
                                                    OmpPrivParm);
}
IsCorrect = IsCorrect && SubstCombiner &&
            (!Init ||
             (D->getInitializerKind() == OMPDeclareReductionDecl::CallInit &&
              SubstInitializer) ||
             (D->getInitializerKind() != OMPDeclareReductionDecl::CallInit &&
              !SubstInitializer));

(void)SemaRef.ActOnOpenMPDeclareReductionDirectiveEnd(
    /*S=*/nullptr, DRD, IsCorrect && !D->isInvalidDecl());

return NewDRD;
3491}

3493Decl *
3494TemplateDeclInstantiator::VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D) {
// Instantiate type and check if it is allowed.
const bool RequiresInstantiation =
    D->getType()->isDependentType() ||
    D->getType()->isInstantiationDependentType() ||
    D->getType()->containsUnexpandedParameterPack();
QualType SubstMapperTy;
DeclarationName VN = D->getVarName();
if (RequiresInstantiation) {
  SubstMapperTy = SemaRef.ActOnOpenMPDeclareMapperType(
      D->getLocation(),
      ParsedType::make(SemaRef.SubstType(D->getType(), TemplateArgs,
                                         D->getLocation(), VN)));
} else {
  SubstMapperTy = D->getType();
}
if (SubstMapperTy.isNull())
  return nullptr;
// Create an instantiated copy of mapper.
auto *PrevDeclInScope = D->getPrevDeclInScope();
if (PrevDeclInScope && !PrevDeclInScope->isInvalidDecl()) {
  PrevDeclInScope = cast<OMPDeclareMapperDecl>(
      SemaRef.CurrentInstantiationScope->findInstantiationOf(PrevDeclInScope)
          ->get<Decl *>());
}
bool IsCorrect = true;
SmallVector<OMPClause *, 6> Clauses;
// Instantiate the mapper variable.
DeclarationNameInfo DirName;
SemaRef.StartOpenMPDSABlock(llvm::omp::OMPD_declare_mapper, DirName,
                            /*S=*/nullptr,
                            (*D->clauselist_begin())->getBeginLoc());
ExprResult MapperVarRef = SemaRef.ActOnOpenMPDeclareMapperDirectiveVarDecl(
    /*S=*/nullptr, SubstMapperTy, D->getLocation(), VN);
SemaRef.CurrentInstantiationScope->InstantiatedLocal(
    cast<DeclRefExpr>(D->getMapperVarRef())->getDecl(),
    cast<DeclRefExpr>(MapperVarRef.get())->getDecl());
auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(Owner);
Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext, Qualifiers(),
                                 ThisContext);
// Instantiate map clauses.
for (OMPClause *C : D->clauselists()) {
  auto *OldC = cast<OMPMapClause>(C);
  SmallVector<Expr *, 4> NewVars;
  for (Expr *OE : OldC->varlists()) {
    Expr *NE = SemaRef.SubstExpr(OE, TemplateArgs).get();
    if (!NE) {
      IsCorrect = false;
      break;
    }
    NewVars.push_back(NE);
  }
  if (!IsCorrect)
    break;
  NestedNameSpecifierLoc NewQualifierLoc =
      SemaRef.SubstNestedNameSpecifierLoc(OldC->getMapperQualifierLoc(),
                                          TemplateArgs);
  CXXScopeSpec SS;
  SS.Adopt(NewQualifierLoc);
  DeclarationNameInfo NewNameInfo =
      SemaRef.SubstDeclarationNameInfo(OldC->getMapperIdInfo(), TemplateArgs);
  OMPVarListLocTy Locs(OldC->getBeginLoc(), OldC->getLParenLoc(),
                       OldC->getEndLoc());
  OMPClause *NewC = SemaRef.ActOnOpenMPMapClause(
      OldC->getMapTypeModifiers(), OldC->getMapTypeModifiersLoc(), SS,
      NewNameInfo, OldC->getMapType(), OldC->isImplicitMapType(),
      OldC->getMapLoc(), OldC->getColonLoc(), NewVars, Locs);
  Clauses.push_back(NewC);
}
SemaRef.EndOpenMPDSABlock(nullptr);
if (!IsCorrect)
  return nullptr;
Sema::DeclGroupPtrTy DG = SemaRef.ActOnOpenMPDeclareMapperDirective(
    /*S=*/nullptr, Owner, D->getDeclName(), SubstMapperTy, D->getLocation(),
    VN, D->getAccess(), MapperVarRef.get(), Clauses, PrevDeclInScope);
Decl *NewDMD = DG.get().getSingleDecl();
SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewDMD);
return NewDMD;
3572}

3574Decl *TemplateDeclInstantiator::VisitOMPCapturedExprDecl(
  OMPCapturedExprDecl * /*D*/) {
llvm_unreachable("Should not be met in templates")__builtin_unreachable();
3577}

3579Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D) {
return VisitFunctionDecl(D, nullptr);
3581}

3583Decl *
3584TemplateDeclInstantiator::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
Decl *Inst = VisitFunctionDecl(D, nullptr);
if (Inst && !D->getDescribedFunctionTemplate())
  Owner->addDecl(Inst);
return Inst;
3589}

3591Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D) {
return VisitCXXMethodDecl(D, nullptr);
3593}

3595Decl *TemplateDeclInstantiator::VisitRecordDecl(RecordDecl *D) {
llvm_unreachable("There are only CXXRecordDecls in C++")__builtin_unreachable();
3597}

3599Decl *
3600TemplateDeclInstantiator::VisitClassTemplateSpecializationDecl(
  ClassTemplateSpecializationDecl *D) {
// As a MS extension, we permit class-scope explicit specialization
// of member class templates.
ClassTemplateDecl *ClassTemplate = D->getSpecializedTemplate();
assert(ClassTemplate->getDeclContext()->isRecord() &&((void)0)
       D->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&((void)0)
       "can only instantiate an explicit specialization "((void)0)
       "for a member class template")((void)0);

// Lookup the already-instantiated declaration in the instantiation
// of the class template.
ClassTemplateDecl *InstClassTemplate =
    cast_or_null<ClassTemplateDecl>(SemaRef.FindInstantiatedDecl(
        D->getLocation(), ClassTemplate, TemplateArgs));
if (!InstClassTemplate)
  return nullptr;

// Substitute into the template arguments of the class template explicit
// specialization.
TemplateSpecializationTypeLoc Loc = D->getTypeAsWritten()->getTypeLoc().
                                      castAs<TemplateSpecializationTypeLoc>();
TemplateArgumentListInfo InstTemplateArgs(Loc.getLAngleLoc(),
                                          Loc.getRAngleLoc());
SmallVector<TemplateArgumentLoc, 4> ArgLocs;
for (unsigned I = 0; I != Loc.getNumArgs(); ++I)
  ArgLocs.push_back(Loc.getArgLoc(I));
if (SemaRef.Subst(ArgLocs.data(), ArgLocs.size(),
                  InstTemplateArgs, TemplateArgs))
  return nullptr;

// Check that the template argument list is well-formed for this
// class template.
SmallVector<TemplateArgument, 4> Converted;
if (SemaRef.CheckTemplateArgumentList(InstClassTemplate,
                                      D->getLocation(),
                                      InstTemplateArgs,
                                      false,
                                      Converted,
                                      /*UpdateArgsWithConversion=*/true))
  return nullptr;

// Figure out where to insert this class template explicit specialization
// in the member template's set of class template explicit specializations.
void *InsertPos = nullptr;
ClassTemplateSpecializationDecl *PrevDecl =
    InstClassTemplate->findSpecialization(Converted, InsertPos);

// Check whether we've already seen a conflicting instantiation of this
// declaration (for instance, if there was a prior implicit instantiation).
bool Ignored;
if (PrevDecl &&
    SemaRef.CheckSpecializationInstantiationRedecl(D->getLocation(),
                                                   D->getSpecializationKind(),
                                                   PrevDecl,
                                                   PrevDecl->getSpecializationKind(),
                                                   PrevDecl->getPointOfInstantiation(),
                                                   Ignored))
  return nullptr;

// If PrevDecl was a definition and D is also a definition, diagnose.
// This happens in cases like:
//
//   template<typename T, typename U>
//   struct Outer {
//     template<typename X> struct Inner;
//     template<> struct Inner<T> {};
//     template<> struct Inner<U> {};
//   };
//
//   Outer<int, int> outer; // error: the explicit specializations of Inner
//                          // have the same signature.
if (PrevDecl && PrevDecl->getDefinition() &&
    D->isThisDeclarationADefinition()) {
  SemaRef.Diag(D->getLocation(), diag::err_redefinition) << PrevDecl;
  SemaRef.Diag(PrevDecl->getDefinition()->getLocation(),
               diag::note_previous_definition);
  return nullptr;
}

// Create the class template partial specialization declaration.
ClassTemplateSpecializationDecl *InstD =
    ClassTemplateSpecializationDecl::Create(
        SemaRef.Context, D->getTagKind(), Owner, D->getBeginLoc(),
        D->getLocation(), InstClassTemplate, Converted, PrevDecl);

// Add this partial specialization to the set of class template partial
// specializations.
if (!PrevDecl)
  InstClassTemplate->AddSpecialization(InstD, InsertPos);

// Substitute the nested name specifier, if any.
if (SubstQualifier(D, InstD))
  return nullptr;

// Build the canonical type that describes the converted template
// arguments of the class template explicit specialization.
QualType CanonType = SemaRef.Context.getTemplateSpecializationType(
    TemplateName(InstClassTemplate), Converted,
    SemaRef.Context.getRecordType(InstD));

// Build the fully-sugared type for this class template
// specialization as the user wrote in the specialization
// itself. This means that we'll pretty-print the type retrieved
// from the specialization's declaration the way that the user
// actually wrote the specialization, rather than formatting the
// name based on the "canonical" representation used to store the
// template arguments in the specialization.
TypeSourceInfo *WrittenTy = SemaRef.Context.getTemplateSpecializationTypeInfo(
    TemplateName(InstClassTemplate), D->getLocation(), InstTemplateArgs,
    CanonType);

InstD->setAccess(D->getAccess());
InstD->setInstantiationOfMemberClass(D, TSK_ImplicitInstantiation);
InstD->setSpecializationKind(D->getSpecializationKind());
InstD->setTypeAsWritten(WrittenTy);
InstD->setExternLoc(D->getExternLoc());
InstD->setTemplateKeywordLoc(D->getTemplateKeywordLoc());

Owner->addDecl(InstD);

// Instantiate the members of the class-scope explicit specialization eagerly.
// We don't have support for lazy instantiation of an explicit specialization
// yet, and MSVC eagerly instantiates in this case.
// FIXME: This is wrong in standard C++.
if (D->isThisDeclarationADefinition() &&
    SemaRef.InstantiateClass(D->getLocation(), InstD, D, TemplateArgs,
                             TSK_ImplicitInstantiation,
                             /*Complain=*/true))
  return nullptr;

return InstD;
3732}

3734Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
  VarTemplateSpecializationDecl *D) {

TemplateArgumentListInfo VarTemplateArgsInfo;
VarTemplateDecl *VarTemplate = D->getSpecializedTemplate();
assert(VarTemplate &&((void)0)
       "A template specialization without specialized template?")((void)0);

VarTemplateDecl *InstVarTemplate =
    cast_or_null<VarTemplateDecl>(SemaRef.FindInstantiatedDecl(
        D->getLocation(), VarTemplate, TemplateArgs));
if (!InstVarTemplate)
  return nullptr;

// Substitute the current template arguments.
const TemplateArgumentListInfo &TemplateArgsInfo = D->getTemplateArgsInfo();
VarTemplateArgsInfo.setLAngleLoc(TemplateArgsInfo.getLAngleLoc());
VarTemplateArgsInfo.setRAngleLoc(TemplateArgsInfo.getRAngleLoc());

if (SemaRef.Subst(TemplateArgsInfo.getArgumentArray(),
                  TemplateArgsInfo.size(), VarTemplateArgsInfo, TemplateArgs))
  return nullptr;

// Check that the template argument list is well-formed for this template.
SmallVector<TemplateArgument, 4> Converted;
if (SemaRef.CheckTemplateArgumentList(InstVarTemplate, D->getLocation(),
                                      VarTemplateArgsInfo, false, Converted,
                                      /*UpdateArgsWithConversion=*/true))
  return nullptr;

// Check whether we've already seen a declaration of this specialization.
void *InsertPos = nullptr;
VarTemplateSpecializationDecl *PrevDecl =
    InstVarTemplate->findSpecialization(Converted, InsertPos);

// Check whether we've already seen a conflicting instantiation of this
// declaration (for instance, if there was a prior implicit instantiation).
bool Ignored;
if (PrevDecl && SemaRef.CheckSpecializationInstantiationRedecl(
                    D->getLocation(), D->getSpecializationKind(), PrevDecl,
                    PrevDecl->getSpecializationKind(),
                    PrevDecl->getPointOfInstantiation(), Ignored))
  return nullptr;

return VisitVarTemplateSpecializationDecl(
    InstVarTemplate, D, VarTemplateArgsInfo, Converted, PrevDecl);
3780}

3782Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
  VarTemplateDecl *VarTemplate, VarDecl *D,
  const TemplateArgumentListInfo &TemplateArgsInfo,
  ArrayRef<TemplateArgument> Converted,
  VarTemplateSpecializationDecl *PrevDecl) {

// Do substitution on the type of the declaration
TypeSourceInfo *DI =
    SemaRef.SubstType(D->getTypeSourceInfo(), TemplateArgs,
                      D->getTypeSpecStartLoc(), D->getDeclName());
if (!DI)
  return nullptr;

if (DI->getType()->isFunctionType()) {
  SemaRef.Diag(D->getLocation(), diag::err_variable_instantiates_to_function)
      << D->isStaticDataMember() << DI->getType();
  return nullptr;
}

// Build the instantiated declaration
VarTemplateSpecializationDecl *Var = VarTemplateSpecializationDecl::Create(
    SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
    VarTemplate, DI->getType(), DI, D->getStorageClass(), Converted);
Var->setTemplateArgsInfo(TemplateArgsInfo);
if (!PrevDecl) {
  void *InsertPos = nullptr;
  VarTemplate->findSpecialization(Converted, InsertPos);
  VarTemplate->AddSpecialization(Var, InsertPos);
}

if (SemaRef.getLangOpts().OpenCL)
  SemaRef.deduceOpenCLAddressSpace(Var);

// Substitute the nested name specifier, if any.
if (SubstQualifier(D, Var))
  return nullptr;

SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
                                   StartingScope, false, PrevDecl);

return Var;
3823}

3825Decl *TemplateDeclInstantiator::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D) {
llvm_unreachable("@defs is not supported in Objective-C++")__builtin_unreachable();
3827}

3829Decl *TemplateDeclInstantiator::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
// FIXME: We need to be able to instantiate FriendTemplateDecls.
unsigned DiagID = SemaRef.getDiagnostics().getCustomDiagID(
                                             DiagnosticsEngine::Error,
                                             "cannot instantiate %0 yet");
SemaRef.Diag(D->getLocation(), DiagID)
  << D->getDeclKindName();

return nullptr;
3838}

3840Decl *TemplateDeclInstantiator::VisitConceptDecl(ConceptDecl *D) {
llvm_unreachable("Concept definitions cannot reside inside a template")__builtin_unreachable();
3842}

3844Decl *
3845TemplateDeclInstantiator::VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D) {
return RequiresExprBodyDecl::Create(SemaRef.Context, D->getDeclContext(),
                                    D->getBeginLoc());
3848}

3850Decl *TemplateDeclInstantiator::VisitDecl(Decl *D) {
llvm_unreachable("Unexpected decl")__builtin_unreachable();
3852}

3854Decl *Sema::SubstDecl(Decl *D, DeclContext *Owner,
                    const MultiLevelTemplateArgumentList &TemplateArgs) {
TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
if (D->isInvalidDecl())
  return nullptr;

Decl *SubstD;
runWithSufficientStackSpace(D->getLocation(), [&] {
  SubstD = Instantiator.Visit(D);
});
return SubstD;
3865}

3867void TemplateDeclInstantiator::adjustForRewrite(RewriteKind RK,
                                              FunctionDecl *Orig, QualType &T,
                                              TypeSourceInfo *&TInfo,
                                              DeclarationNameInfo &NameInfo) {
assert(RK == RewriteKind::RewriteSpaceshipAsEqualEqual)((void)0);

// C++2a [class.compare.default]p3:
//   the return type is replaced with bool
auto *FPT = T->castAs<FunctionProtoType>();
T = SemaRef.Context.getFunctionType(
    SemaRef.Context.BoolTy, FPT->getParamTypes(), FPT->getExtProtoInfo());

// Update the return type in the source info too. The most straightforward
// way is to create new TypeSourceInfo for the new type. Use the location of
// the '= default' as the location of the new type.
//
// FIXME: Set the correct return type when we initially transform the type,
// rather than delaying it to now.
TypeSourceInfo *NewTInfo =
    SemaRef.Context.getTrivialTypeSourceInfo(T, Orig->getEndLoc());
auto OldLoc = TInfo->getTypeLoc().getAsAdjusted<FunctionProtoTypeLoc>();
assert(OldLoc && "type of function is not a function type?")((void)0);
auto NewLoc = NewTInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>();
for (unsigned I = 0, N = OldLoc.getNumParams(); I != N; ++I)
  NewLoc.setParam(I, OldLoc.getParam(I));
TInfo = NewTInfo;

//   and the declarator-id is replaced with operator==
NameInfo.setName(
    SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_EqualEqual));
3897}

3899FunctionDecl *Sema::SubstSpaceshipAsEqualEqual(CXXRecordDecl *RD,
                                             FunctionDecl *Spaceship) {
if (Spaceship->isInvalidDecl())
  return nullptr;

// C++2a [class.compare.default]p3:
//   an == operator function is declared implicitly [...] with the same
//   access and function-definition and in the same class scope as the
//   three-way comparison operator function
MultiLevelTemplateArgumentList NoTemplateArgs;
NoTemplateArgs.setKind(TemplateSubstitutionKind::Rewrite);
NoTemplateArgs.addOuterRetainedLevels(RD->getTemplateDepth());
TemplateDeclInstantiator Instantiator(*this, RD, NoTemplateArgs);
Decl *R;
if (auto *MD = dyn_cast<CXXMethodDecl>(Spaceship)) {
  R = Instantiator.VisitCXXMethodDecl(
      MD, nullptr, None,
      TemplateDeclInstantiator::RewriteKind::RewriteSpaceshipAsEqualEqual);
} else {
  assert(Spaceship->getFriendObjectKind() &&((void)0)
         "defaulted spaceship is neither a member nor a friend")((void)0);

  R = Instantiator.VisitFunctionDecl(
      Spaceship, nullptr,
      TemplateDeclInstantiator::RewriteKind::RewriteSpaceshipAsEqualEqual);
  if (!R)
    return nullptr;

  FriendDecl *FD =
      FriendDecl::Create(Context, RD, Spaceship->getLocation(),
                         cast<NamedDecl>(R), Spaceship->getBeginLoc());
  FD->setAccess(AS_public);
  RD->addDecl(FD);
}
return cast_or_null<FunctionDecl>(R);
3934}

3936/// Instantiates a nested template parameter list in the current
3937/// instantiation context.
3938///
3939/// \param L The parameter list to instantiate
3940///
3941/// \returns NULL if there was an error
3942TemplateParameterList *
3943TemplateDeclInstantiator::SubstTemplateParams(TemplateParameterList *L) {
// Get errors for all the parameters before bailing out.
bool Invalid = false;

unsigned N = L->size();
typedef SmallVector<NamedDecl *, 8> ParamVector;
ParamVector Params;
Params.reserve(N);
for (auto &P : *L) {
  NamedDecl *D = cast_or_null<NamedDecl>(Visit(P));
  Params.push_back(D);
  Invalid = Invalid || !D || D->isInvalidDecl();
}

// Clean up if we had an error.
if (Invalid)
  return nullptr;

// FIXME: Concepts: Substitution into requires clause should only happen when
// checking satisfaction.
Expr *InstRequiresClause = nullptr;
if (Expr *E = L->getRequiresClause()) {
  EnterExpressionEvaluationContext ConstantEvaluated(
      SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
  ExprResult Res = SemaRef.SubstExpr(E, TemplateArgs);
  if (Res.isInvalid() || !Res.isUsable()) {
    return nullptr;
  }
  InstRequiresClause = Res.get();
}

TemplateParameterList *InstL
  = TemplateParameterList::Create(SemaRef.Context, L->getTemplateLoc(),
                                  L->getLAngleLoc(), Params,
                                  L->getRAngleLoc(), InstRequiresClause);
return InstL;
3979}

3981TemplateParameterList *
3982Sema::SubstTemplateParams(TemplateParameterList *Params, DeclContext *Owner,
                        const MultiLevelTemplateArgumentList &TemplateArgs) {
TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
return Instantiator.SubstTemplateParams(Params);
3986}

3988/// Instantiate the declaration of a class template partial
3989/// specialization.
3990///
3991/// \param ClassTemplate the (instantiated) class template that is partially
3992// specialized by the instantiation of \p PartialSpec.
3993///
3994/// \param PartialSpec the (uninstantiated) class template partial
3995/// specialization that we are instantiating.
3996///
3997/// \returns The instantiated partial specialization, if successful; otherwise,
3998/// NULL to indicate an error.
3999ClassTemplatePartialSpecializationDecl *
4000TemplateDeclInstantiator::InstantiateClassTemplatePartialSpecialization(
                                          ClassTemplateDecl *ClassTemplate,
                        ClassTemplatePartialSpecializationDecl *PartialSpec) {
// Create a local instantiation scope for this class template partial
// specialization, which will contain the instantiations of the template
// parameters.
LocalInstantiationScope Scope(SemaRef);

// Substitute into the template parameters of the class template partial
// specialization.
TemplateParameterList *TempParams = PartialSpec->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

// Substitute into the template arguments of the class template partial
// specialization.
const ASTTemplateArgumentListInfo *TemplArgInfo
  = PartialSpec->getTemplateArgsAsWritten();
TemplateArgumentListInfo InstTemplateArgs(TemplArgInfo->LAngleLoc,
                                          TemplArgInfo->RAngleLoc);
if (SemaRef.Subst(TemplArgInfo->getTemplateArgs(),
                  TemplArgInfo->NumTemplateArgs,
                  InstTemplateArgs, TemplateArgs))
  return nullptr;

// Check that the template argument list is well-formed for this
// class template.
SmallVector<TemplateArgument, 4> Converted;
if (SemaRef.CheckTemplateArgumentList(ClassTemplate,
                                      PartialSpec->getLocation(),
                                      InstTemplateArgs,
                                      false,
                                      Converted))
  return nullptr;

// Check these arguments are valid for a template partial specialization.
if (SemaRef.CheckTemplatePartialSpecializationArgs(
        PartialSpec->getLocation(), ClassTemplate, InstTemplateArgs.size(),
        Converted))
  return nullptr;

// Figure out where to insert this class template partial specialization
// in the member template's set of class template partial specializations.
void *InsertPos = nullptr;
ClassTemplateSpecializationDecl *PrevDecl
  = ClassTemplate->findPartialSpecialization(Converted, InstParams,
                                             InsertPos);

// Build the canonical type that describes the converted template
// arguments of the class template partial specialization.
QualType CanonType
  = SemaRef.Context.getTemplateSpecializationType(TemplateName(ClassTemplate),
                                                  Converted);

// Build the fully-sugared type for this class template
// specialization as the user wrote in the specialization
// itself. This means that we'll pretty-print the type retrieved
// from the specialization's declaration the way that the user
// actually wrote the specialization, rather than formatting the
// name based on the "canonical" representation used to store the
// template arguments in the specialization.
TypeSourceInfo *WrittenTy
  = SemaRef.Context.getTemplateSpecializationTypeInfo(
                                                  TemplateName(ClassTemplate),
                                                  PartialSpec->getLocation(),
                                                  InstTemplateArgs,
                                                  CanonType);

if (PrevDecl) {
  // We've already seen a partial specialization with the same template
  // parameters and template arguments. This can happen, for example, when
  // substituting the outer template arguments ends up causing two
  // class template partial specializations of a member class template
  // to have identical forms, e.g.,
  //
  //   template<typename T, typename U>
  //   struct Outer {
  //     template<typename X, typename Y> struct Inner;
  //     template<typename Y> struct Inner<T, Y>;
  //     template<typename Y> struct Inner<U, Y>;
  //   };
  //
  //   Outer<int, int> outer; // error: the partial specializations of Inner
  //                          // have the same signature.
  SemaRef.Diag(PartialSpec->getLocation(), diag::err_partial_spec_redeclared)
    << WrittenTy->getType();
  SemaRef.Diag(PrevDecl->getLocation(), diag::note_prev_partial_spec_here)
    << SemaRef.Context.getTypeDeclType(PrevDecl);
  return nullptr;
}


// Create the class template partial specialization declaration.
ClassTemplatePartialSpecializationDecl *InstPartialSpec =
    ClassTemplatePartialSpecializationDecl::Create(
        SemaRef.Context, PartialSpec->getTagKind(), Owner,
        PartialSpec->getBeginLoc(), PartialSpec->getLocation(), InstParams,
        ClassTemplate, Converted, InstTemplateArgs, CanonType, nullptr);
// Substitute the nested name specifier, if any.
if (SubstQualifier(PartialSpec, InstPartialSpec))
  return nullptr;

InstPartialSpec->setInstantiatedFromMember(PartialSpec);
InstPartialSpec->setTypeAsWritten(WrittenTy);

// Check the completed partial specialization.
SemaRef.CheckTemplatePartialSpecialization(InstPartialSpec);

// Add this partial specialization to the set of class template partial
// specializations.
ClassTemplate->AddPartialSpecialization(InstPartialSpec,
                                        /*InsertPos=*/nullptr);
return InstPartialSpec;
4114}

4116/// Instantiate the declaration of a variable template partial
4117/// specialization.
4118///
4119/// \param VarTemplate the (instantiated) variable template that is partially
4120/// specialized by the instantiation of \p PartialSpec.
4121///
4122/// \param PartialSpec the (uninstantiated) variable template partial
4123/// specialization that we are instantiating.
4124///
4125/// \returns The instantiated partial specialization, if successful; otherwise,
4126/// NULL to indicate an error.
4127VarTemplatePartialSpecializationDecl *
4128TemplateDeclInstantiator::InstantiateVarTemplatePartialSpecialization(
  VarTemplateDecl *VarTemplate,
  VarTemplatePartialSpecializationDecl *PartialSpec) {
// Create a local instantiation scope for this variable template partial
// specialization, which will contain the instantiations of the template
// parameters.
LocalInstantiationScope Scope(SemaRef);

// Substitute into the template parameters of the variable template partial
// specialization.
TemplateParameterList *TempParams = PartialSpec->getTemplateParameters();
TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
if (!InstParams)
  return nullptr;

// Substitute into the template arguments of the variable template partial
// specialization.
const ASTTemplateArgumentListInfo *TemplArgInfo
  = PartialSpec->getTemplateArgsAsWritten();
TemplateArgumentListInfo InstTemplateArgs(TemplArgInfo->LAngleLoc,
                                          TemplArgInfo->RAngleLoc);
if (SemaRef.Subst(TemplArgInfo->getTemplateArgs(),
                  TemplArgInfo->NumTemplateArgs,
                  InstTemplateArgs, TemplateArgs))
  return nullptr;

// Check that the template argument list is well-formed for this
// class template.
SmallVector<TemplateArgument, 4> Converted;
if (SemaRef.CheckTemplateArgumentList(VarTemplate, PartialSpec->getLocation(),
                                      InstTemplateArgs, false, Converted))
  return nullptr;

// Check these arguments are valid for a template partial specialization.
if (SemaRef.CheckTemplatePartialSpecializationArgs(
        PartialSpec->getLocation(), VarTemplate, InstTemplateArgs.size(),
        Converted))
  return nullptr;

// Figure out where to insert this variable template partial specialization
// in the member template's set of variable template partial specializations.
void *InsertPos = nullptr;
VarTemplateSpecializationDecl *PrevDecl =
    VarTemplate->findPartialSpecialization(Converted, InstParams, InsertPos);

// Build the canonical type that describes the converted template
// arguments of the variable template partial specialization.
QualType CanonType = SemaRef.Context.getTemplateSpecializationType(
    TemplateName(VarTemplate), Converted);

// Build the fully-sugared type for this variable template
// specialization as the user wrote in the specialization
// itself. This means that we'll pretty-print the type retrieved
// from the specialization's declaration the way that the user
// actually wrote the specialization, rather than formatting the
// name based on the "canonical" representation used to store the
// template arguments in the specialization.
TypeSourceInfo *WrittenTy = SemaRef.Context.getTemplateSpecializationTypeInfo(
    TemplateName(VarTemplate), PartialSpec->getLocation(), InstTemplateArgs,
    CanonType);

if (PrevDecl) {
  // We've already seen a partial specialization with the same template
  // parameters and template arguments. This can happen, for example, when
  // substituting the outer template arguments ends up causing two
  // variable template partial specializations of a member variable template
  // to have identical forms, e.g.,
  //
  //   template<typename T, typename U>
  //   struct Outer {
  //     template<typename X, typename Y> pair<X,Y> p;
  //     template<typename Y> pair<T, Y> p;
  //     template<typename Y> pair<U, Y> p;
  //   };
  //
  //   Outer<int, int> outer; // error: the partial specializations of Inner
  //                          // have the same signature.
  SemaRef.Diag(PartialSpec->getLocation(),
               diag::err_var_partial_spec_redeclared)
      << WrittenTy->getType();
  SemaRef.Diag(PrevDecl->getLocation(),
               diag::note_var_prev_partial_spec_here);
  return nullptr;
}

// Do substitution on the type of the declaration
TypeSourceInfo *DI = SemaRef.SubstType(
    PartialSpec->getTypeSourceInfo(), TemplateArgs,
    PartialSpec->getTypeSpecStartLoc(), PartialSpec->getDeclName());
if (!DI)
  return nullptr;

if (DI->getType()->isFunctionType()) {
  SemaRef.Diag(PartialSpec->getLocation(),
               diag::err_variable_instantiates_to_function)
      << PartialSpec->isStaticDataMember() << DI->getType();
  return nullptr;
}

// Create the variable template partial specialization declaration.
VarTemplatePartialSpecializationDecl *InstPartialSpec =
    VarTemplatePartialSpecializationDecl::Create(
        SemaRef.Context, Owner, PartialSpec->getInnerLocStart(),
        PartialSpec->getLocation(), InstParams, VarTemplate, DI->getType(),
        DI, PartialSpec->getStorageClass(), Converted, InstTemplateArgs);

// Substitute the nested name specifier, if any.
if (SubstQualifier(PartialSpec, InstPartialSpec))
  return nullptr;

InstPartialSpec->setInstantiatedFromMember(PartialSpec);
InstPartialSpec->setTypeAsWritten(WrittenTy);

// Check the completed partial specialization.
SemaRef.CheckTemplatePartialSpecialization(InstPartialSpec);

// Add this partial specialization to the set of variable template partial
// specializations. The instantiation of the initializer is not necessary.
VarTemplate->AddPartialSpecialization(InstPartialSpec, /*InsertPos=*/nullptr);

SemaRef.BuildVariableInstantiation(InstPartialSpec, PartialSpec, TemplateArgs,
                                   LateAttrs, Owner, StartingScope);

return InstPartialSpec;
4252}

4254TypeSourceInfo*
4255TemplateDeclInstantiator::SubstFunctionType(FunctionDecl *D,
                            SmallVectorImpl<ParmVarDecl *> &Params) {
TypeSourceInfo *OldTInfo = D->getTypeSourceInfo();
assert(OldTInfo && "substituting function without type source info")((void)0);
assert(Params.empty() && "parameter vector is non-empty at start")((void)0);

CXXRecordDecl *ThisContext = nullptr;
Qualifiers ThisTypeQuals;
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
  ThisContext = cast<CXXRecordDecl>(Owner);
  ThisTypeQuals = Method->getMethodQualifiers();
}

TypeSourceInfo *NewTInfo
  = SemaRef.SubstFunctionDeclType(OldTInfo, TemplateArgs,
                                  D->getTypeSpecStartLoc(),
                                  D->getDeclName(),
                                  ThisContext, ThisTypeQuals);
if (!NewTInfo)
  return nullptr;

TypeLoc OldTL = OldTInfo->getTypeLoc().IgnoreParens();
if (FunctionProtoTypeLoc OldProtoLoc = OldTL.getAs<FunctionProtoTypeLoc>()) {
  if (NewTInfo != OldTInfo) {
    // Get parameters from the new type info.
    TypeLoc NewTL = NewTInfo->getTypeLoc().IgnoreParens();
    FunctionProtoTypeLoc NewProtoLoc = NewTL.castAs<FunctionProtoTypeLoc>();
    unsigned NewIdx = 0;
    for (unsigned OldIdx = 0, NumOldParams = OldProtoLoc.getNumParams();
         OldIdx != NumOldParams; ++OldIdx) {
      ParmVarDecl *OldParam = OldProtoLoc.getParam(OldIdx);
      if (!OldParam)
        return nullptr;

      LocalInstantiationScope *Scope = SemaRef.CurrentInstantiationScope;

      Optional<unsigned> NumArgumentsInExpansion;
      if (OldParam->isParameterPack())
        NumArgumentsInExpansion =
            SemaRef.getNumArgumentsInExpansion(OldParam->getType(),
                                               TemplateArgs);
      if (!NumArgumentsInExpansion) {
        // Simple case: normal parameter, or a parameter pack that's
        // instantiated to a (still-dependent) parameter pack.
        ParmVarDecl *NewParam = NewProtoLoc.getParam(NewIdx++);
        Params.push_back(NewParam);
        Scope->InstantiatedLocal(OldParam, NewParam);
      } else {
        // Parameter pack expansion: make the instantiation an argument pack.
        Scope->MakeInstantiatedLocalArgPack(OldParam);
        for (unsigned I = 0; I != *NumArgumentsInExpansion; ++I) {
          ParmVarDecl *NewParam = NewProtoLoc.getParam(NewIdx++);
          Params.push_back(NewParam);
          Scope->InstantiatedLocalPackArg(OldParam, NewParam);
        }
      }
    }
  } else {
    // The function type itself was not dependent and therefore no
    // substitution occurred. However, we still need to instantiate
    // the function parameters themselves.
    const FunctionProtoType *OldProto =
        cast<FunctionProtoType>(OldProtoLoc.getType());
    for (unsigned i = 0, i_end = OldProtoLoc.getNumParams(); i != i_end;
         ++i) {
      ParmVarDecl *OldParam = OldProtoLoc.getParam(i);
      if (!OldParam) {
        Params.push_back(SemaRef.BuildParmVarDeclForTypedef(
            D, D->getLocation(), OldProto->getParamType(i)));
        continue;
      }

      ParmVarDecl *Parm =
          cast_or_null<ParmVarDecl>(VisitParmVarDecl(OldParam));
      if (!Parm)
        return nullptr;
      Params.push_back(Parm);
    }
  }
} else {
  // If the type of this function, after ignoring parentheses, is not
  // *directly* a function type, then we're instantiating a function that
  // was declared via a typedef or with attributes, e.g.,
  //
  //   typedef int functype(int, int);
  //   functype func;
  //   int __cdecl meth(int, int);
  //
  // In this case, we'll just go instantiate the ParmVarDecls that we
  // synthesized in the method declaration.
  SmallVector<QualType, 4> ParamTypes;
  Sema::ExtParameterInfoBuilder ExtParamInfos;
  if (SemaRef.SubstParmTypes(D->getLocation(), D->parameters(), nullptr,
                             TemplateArgs, ParamTypes, &Params,
                             ExtParamInfos))
    return nullptr;
}

return NewTInfo;
4354}

4356/// Introduce the instantiated function parameters into the local
4357/// instantiation scope, and set the parameter names to those used
4358/// in the template.
4359static bool addInstantiatedParametersToScope(Sema &S, FunctionDecl *Function,
                                           const FunctionDecl *PatternDecl,
                                           LocalInstantiationScope &Scope,
                         const MultiLevelTemplateArgumentList &TemplateArgs) {
unsigned FParamIdx = 0;
for (unsigned I = 0, N = PatternDecl->getNumParams(); I != N; ++I) {
  const ParmVarDecl *PatternParam = PatternDecl->getParamDecl(I);
  if (!PatternParam->isParameterPack()) {
    // Simple case: not a parameter pack.
    assert(FParamIdx < Function->getNumParams())((void)0);
    ParmVarDecl *FunctionParam = Function->getParamDecl(FParamIdx);
    FunctionParam->setDeclName(PatternParam->getDeclName());
    // If the parameter's type is not dependent, update it to match the type
    // in the pattern. They can differ in top-level cv-qualifiers, and we want
    // the pattern's type here. If the type is dependent, they can't differ,
    // per core issue 1668. Substitute into the type from the pattern, in case
    // it's instantiation-dependent.
    // FIXME: Updating the type to work around this is at best fragile.
    if (!PatternDecl->getType()->isDependentType()) {
      QualType T = S.SubstType(PatternParam->getType(), TemplateArgs,
                               FunctionParam->getLocation(),
                               FunctionParam->getDeclName());
      if (T.isNull())
        return true;
      FunctionParam->setType(T);
    }

    Scope.InstantiatedLocal(PatternParam, FunctionParam);
    ++FParamIdx;
    continue;
  }

  // Expand the parameter pack.
  Scope.MakeInstantiatedLocalArgPack(PatternParam);
  Optional<unsigned> NumArgumentsInExpansion
    = S.getNumArgumentsInExpansion(PatternParam->getType(), TemplateArgs);
  if (NumArgumentsInExpansion) {
    QualType PatternType =
        PatternParam->getType()->castAs<PackExpansionType>()->getPattern();
    for (unsigned Arg = 0; Arg < *NumArgumentsInExpansion; ++Arg) {
      ParmVarDecl *FunctionParam = Function->getParamDecl(FParamIdx);
      FunctionParam->setDeclName(PatternParam->getDeclName());
      if (!PatternDecl->getType()->isDependentType()) {
        Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(S, Arg);
        QualType T = S.SubstType(PatternType, TemplateArgs,
                                 FunctionParam->getLocation(),
                                 FunctionParam->getDeclName());
        if (T.isNull())
          return true;
        FunctionParam->setType(T);
      }

      Scope.InstantiatedLocalPackArg(PatternParam, FunctionParam);
      ++FParamIdx;
    }
  }
}

return false;
4418}

4420bool Sema::InstantiateDefaultArgument(SourceLocation CallLoc, FunctionDecl *FD,
                                    ParmVarDecl *Param) {
assert(Param->hasUninstantiatedDefaultArg())((void)0);
Expr *UninstExpr = Param->getUninstantiatedDefaultArg();

EnterExpressionEvaluationContext EvalContext(
    *this, ExpressionEvaluationContext::PotentiallyEvaluated, Param);

// Instantiate the expression.
//
// FIXME: Pass in a correct Pattern argument, otherwise
// getTemplateInstantiationArgs uses the lexical context of FD, e.g.
//
// template<typename T>
// struct A {
//   static int FooImpl();
//
//   template<typename Tp>
//   // bug: default argument A<T>::FooImpl() is evaluated with 2-level
//   // template argument list [[T], [Tp]], should be [[Tp]].
//   friend A<Tp> Foo(int a);
// };
//
// template<typename T>
// A<T> Foo(int a = A<T>::FooImpl());
MultiLevelTemplateArgumentList TemplateArgs
  = getTemplateInstantiationArgs(FD, nullptr, /*RelativeToPrimary=*/true);

InstantiatingTemplate Inst(*this, CallLoc, Param,
                           TemplateArgs.getInnermost());
if (Inst.isInvalid())
  return true;
if (Inst.isAlreadyInstantiating()) {
  Diag(Param->getBeginLoc(), diag::err_recursive_default_argument) << FD;
  Param->setInvalidDecl();
  return true;
}

ExprResult Result;
{
  // C++ [dcl.fct.default]p5:
  //   The names in the [default argument] expression are bound, and
  //   the semantic constraints are checked, at the point where the
  //   default argument expression appears.
  ContextRAII SavedContext(*this, FD);
  LocalInstantiationScope Local(*this);

  FunctionDecl *Pattern = FD->getTemplateInstantiationPattern(
      /*ForDefinition*/ false);
  if (addInstantiatedParametersToScope(*this, FD, Pattern, Local,
                                       TemplateArgs))
    return true;

  runWithSufficientStackSpace(CallLoc, [&] {
    Result = SubstInitializer(UninstExpr, TemplateArgs,
                              /*DirectInit*/false);
  });
}
if (Result.isInvalid())
  return true;

// Check the expression as an initializer for the parameter.
InitializedEntity Entity
  = InitializedEntity::InitializeParameter(Context, Param);
InitializationKind Kind = InitializationKind::CreateCopy(
    Param->getLocation(),
    /*FIXME:EqualLoc*/ UninstExpr->getBeginLoc());
Expr *ResultE = Result.getAs<Expr>();

InitializationSequence InitSeq(*this, Entity, Kind, ResultE);
Result = InitSeq.Perform(*this, Entity, Kind, ResultE);
if (Result.isInvalid())
  return true;

Result =
    ActOnFinishFullExpr(Result.getAs<Expr>(), Param->getOuterLocStart(),
                        /*DiscardedValue*/ false);
if (Result.isInvalid())
  return true;

// Remember the instantiated default argument.
Param->setDefaultArg(Result.getAs<Expr>());
if (ASTMutationListener *L = getASTMutationListener())
  L->DefaultArgumentInstantiated(Param);

return false;
4506}

4508void Sema::InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
                                  FunctionDecl *Decl) {
const FunctionProtoType *Proto = Decl->getType()->castAs<FunctionProtoType>();
if (Proto->getExceptionSpecType() != EST_Uninstantiated)
  return;

InstantiatingTemplate Inst(*this, PointOfInstantiation, Decl,
                           InstantiatingTemplate::ExceptionSpecification());
if (Inst.isInvalid()) {
  // We hit the instantiation depth limit. Clear the exception specification
  // so that our callers don't have to cope with EST_Uninstantiated.
  UpdateExceptionSpec(Decl, EST_None);
  return;
}
if (Inst.isAlreadyInstantiating()) {
  // This exception specification indirectly depends on itself. Reject.
  // FIXME: Corresponding rule in the standard?
  Diag(PointOfInstantiation, diag::err_exception_spec_cycle) << Decl;
  UpdateExceptionSpec(Decl, EST_None);
  return;
}

// Enter the scope of this instantiation. We don't use
// PushDeclContext because we don't have a scope.
Sema::ContextRAII savedContext(*this, Decl);
LocalInstantiationScope Scope(*this);

MultiLevelTemplateArgumentList TemplateArgs =
  getTemplateInstantiationArgs(Decl, nullptr, /*RelativeToPrimary*/true);

// FIXME: We can't use getTemplateInstantiationPattern(false) in general
// here, because for a non-defining friend declaration in a class template,
// we don't store enough information to map back to the friend declaration in
// the template.
FunctionDecl *Template = Proto->getExceptionSpecTemplate();
if (addInstantiatedParametersToScope(*this, Decl, Template, Scope,
                                     TemplateArgs)) {
  UpdateExceptionSpec(Decl, EST_None);
  return;
}

SubstExceptionSpec(Decl, Template->getType()->castAs<FunctionProtoType>(),
                   TemplateArgs);
4551}

4553bool Sema::CheckInstantiatedFunctionTemplateConstraints(
  SourceLocation PointOfInstantiation, FunctionDecl *Decl,
  ArrayRef<TemplateArgument> TemplateArgs,
  ConstraintSatisfaction &Satisfaction) {
// In most cases we're not going to have constraints, so check for that first.
FunctionTemplateDecl *Template = Decl->getPrimaryTemplate();
// Note - code synthesis context for the constraints check is created
// inside CheckConstraintsSatisfaction.
SmallVector<const Expr *, 3> TemplateAC;
Template->getAssociatedConstraints(TemplateAC);
if (TemplateAC.empty()) {
  Satisfaction.IsSatisfied = true;
  return false;
}

// Enter the scope of this instantiation. We don't use
// PushDeclContext because we don't have a scope.
Sema::ContextRAII savedContext(*this, Decl);
LocalInstantiationScope Scope(*this);

// If this is not an explicit specialization - we need to get the instantiated
// version of the template arguments and add them to scope for the
// substitution.
if (Decl->isTemplateInstantiation()) {
  InstantiatingTemplate Inst(*this, Decl->getPointOfInstantiation(),
      InstantiatingTemplate::ConstraintsCheck{}, Decl->getPrimaryTemplate(),
      TemplateArgs, SourceRange());
  if (Inst.isInvalid())
    return true;
  MultiLevelTemplateArgumentList MLTAL(
      *Decl->getTemplateSpecializationArgs());
  if (addInstantiatedParametersToScope(
          *this, Decl, Decl->getPrimaryTemplate()->getTemplatedDecl(),
          Scope, MLTAL))
    return true;
}
Qualifiers ThisQuals;
CXXRecordDecl *Record = nullptr;
if (auto *Method = dyn_cast<CXXMethodDecl>(Decl)) {
  ThisQuals = Method->getMethodQualifiers();
  Record = Method->getParent();
}
CXXThisScopeRAII ThisScope(*this, Record, ThisQuals, Record != nullptr);
return CheckConstraintSatisfaction(Template, TemplateAC, TemplateArgs,
                                   PointOfInstantiation, Satisfaction);
4598}

4600/// Initializes the common fields of an instantiation function
4601/// declaration (New) from the corresponding fields of its template (Tmpl).
4602///
4603/// \returns true if there was an error
4604bool
4605TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
                                                  FunctionDecl *Tmpl) {
New->setImplicit(Tmpl->isImplicit());

// Forward the mangling number from the template to the instantiated decl.
SemaRef.Context.setManglingNumber(New,
                                  SemaRef.Context.getManglingNumber(Tmpl));

// If we are performing substituting explicitly-specified template arguments
// or deduced template arguments into a function template and we reach this
// point, we are now past the point where SFINAE applies and have committed
// to keeping the new function template specialization. We therefore
// convert the active template instantiation for the function template
// into a template instantiation for this specific function template
// specialization, which is not a SFINAE context, so that we diagnose any
// further errors in the declaration itself.
//
// FIXME: This is a hack.
typedef Sema::CodeSynthesisContext ActiveInstType;
ActiveInstType &ActiveInst = SemaRef.CodeSynthesisContexts.back();
if (ActiveInst.Kind == ActiveInstType::ExplicitTemplateArgumentSubstitution ||
    ActiveInst.Kind == ActiveInstType::DeducedTemplateArgumentSubstitution) {
  if (FunctionTemplateDecl *FunTmpl
        = dyn_cast<FunctionTemplateDecl>(ActiveInst.Entity)) {
    assert(FunTmpl->getTemplatedDecl() == Tmpl &&((void)0)
           "Deduction from the wrong function template?")((void)0);
    (void) FunTmpl;
    SemaRef.InstantiatingSpecializations.erase(
        {ActiveInst.Entity->getCanonicalDecl(), ActiveInst.Kind});
    atTemplateEnd(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
    ActiveInst.Kind = ActiveInstType::TemplateInstantiation;
    ActiveInst.Entity = New;
    atTemplateBegin(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
  }
}

const FunctionProtoType *Proto = Tmpl->getType()->getAs<FunctionProtoType>();
assert(Proto && "Function template without prototype?")((void)0);

if (Proto->hasExceptionSpec() || Proto->getNoReturnAttr()) {
  FunctionProtoType::ExtProtoInfo EPI = Proto->getExtProtoInfo();

  // DR1330: In C++11, defer instantiation of a non-trivial
  // exception specification.
  // DR1484: Local classes and their members are instantiated along with the
  // containing function.
  if (SemaRef.getLangOpts().CPlusPlus11 &&
      EPI.ExceptionSpec.Type != EST_None &&
      EPI.ExceptionSpec.Type != EST_DynamicNone &&
      EPI.ExceptionSpec.Type != EST_BasicNoexcept &&
      !Tmpl->isInLocalScopeForInstantiation()) {
    FunctionDecl *ExceptionSpecTemplate = Tmpl;
    if (EPI.ExceptionSpec.Type == EST_Uninstantiated)
      ExceptionSpecTemplate = EPI.ExceptionSpec.SourceTemplate;
    ExceptionSpecificationType NewEST = EST_Uninstantiated;
    if (EPI.ExceptionSpec.Type == EST_Unevaluated)
      NewEST = EST_Unevaluated;

    // Mark the function has having an uninstantiated exception specification.
    const FunctionProtoType *NewProto
      = New->getType()->getAs<FunctionProtoType>();
    assert(NewProto && "Template instantiation without function prototype?")((void)0);
    EPI = NewProto->getExtProtoInfo();
    EPI.ExceptionSpec.Type = NewEST;
    EPI.ExceptionSpec.SourceDecl = New;
    EPI.ExceptionSpec.SourceTemplate = ExceptionSpecTemplate;
    New->setType(SemaRef.Context.getFunctionType(
        NewProto->getReturnType(), NewProto->getParamTypes(), EPI));
  } else {
    Sema::ContextRAII SwitchContext(SemaRef, New);
    SemaRef.SubstExceptionSpec(New, Proto, TemplateArgs);
  }
}

// Get the definition. Leaves the variable unchanged if undefined.
const FunctionDecl *Definition = Tmpl;
Tmpl->isDefined(Definition);

SemaRef.InstantiateAttrs(TemplateArgs, Definition, New,
                         LateAttrs, StartingScope);

return false;
4687}

4689/// Initializes common fields of an instantiated method
4690/// declaration (New) from the corresponding fields of its template
4691/// (Tmpl).
4692///
4693/// \returns true if there was an error
4694bool
4695TemplateDeclInstantiator::InitMethodInstantiation(CXXMethodDecl *New,
                                                CXXMethodDecl *Tmpl) {
if (InitFunctionInstantiation(New, Tmpl))
  return true;

if (isa<CXXDestructorDecl>(New) && SemaRef.getLangOpts().CPlusPlus11)
  SemaRef.AdjustDestructorExceptionSpec(cast<CXXDestructorDecl>(New));

New->setAccess(Tmpl->getAccess());
if (Tmpl->isVirtualAsWritten())
  New->setVirtualAsWritten(true);

// FIXME: New needs a pointer to Tmpl
return false;
4709}

4711bool TemplateDeclInstantiator::SubstDefaultedFunction(FunctionDecl *New,
                                                    FunctionDecl *Tmpl) {
// Transfer across any unqualified lookups.
if (auto *DFI = Tmpl->getDefaultedFunctionInfo()) {
  SmallVector<DeclAccessPair, 32> Lookups;
  Lookups.reserve(DFI->getUnqualifiedLookups().size());
  bool AnyChanged = false;
  for (DeclAccessPair DA : DFI->getUnqualifiedLookups()) {
    NamedDecl *D = SemaRef.FindInstantiatedDecl(New->getLocation(),
                                                DA.getDecl(), TemplateArgs);
    if (!D)
      return true;
    AnyChanged |= (D != DA.getDecl());
    Lookups.push_back(DeclAccessPair::make(D, DA.getAccess()));
  }

  // It's unlikely that substitution will change any declarations. Don't
  // store an unnecessary copy in that case.
  New->setDefaultedFunctionInfo(
      AnyChanged ? FunctionDecl::DefaultedFunctionInfo::Create(
                       SemaRef.Context, Lookups)
                 : DFI);
}

SemaRef.SetDeclDefaulted(New, Tmpl->getLocation());
return false;
4737}

4739/// Instantiate (or find existing instantiation of) a function template with a
4740/// given set of template arguments.
4741///
4742/// Usually this should not be used, and template argument deduction should be
4743/// used in its place.
4744FunctionDecl *
4745Sema::InstantiateFunctionDeclaration(FunctionTemplateDecl *FTD,
                                   const TemplateArgumentList *Args,
                                   SourceLocation Loc) {
FunctionDecl *FD = FTD->getTemplatedDecl();

sema::TemplateDeductionInfo Info(Loc);
InstantiatingTemplate Inst(
    *this, Loc, FTD, Args->asArray(),
    CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
if (Inst.isInvalid())
  return nullptr;

ContextRAII SavedContext(*this, FD);
MultiLevelTemplateArgumentList MArgs(*Args);

return cast_or_null<FunctionDecl>(SubstDecl(FD, FD->getParent(), MArgs));
4761}

4763/// Instantiate the definition of the given function from its
4764/// template.
4765///
4766/// \param PointOfInstantiation the point at which the instantiation was
4767/// required. Note that this is not precisely a "point of instantiation"
4768/// for the function, but it's close.
4769///
4770/// \param Function the already-instantiated declaration of a
4771/// function template specialization or member function of a class template
4772/// specialization.
4773///
4774/// \param Recursive if true, recursively instantiates any functions that
4775/// are required by this instantiation.
4776///
4777/// \param DefinitionRequired if true, then we are performing an explicit
4778/// instantiation where the body of the function is required. Complain if
4779/// there is no such body.
4780void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
                                       FunctionDecl *Function,
                                       bool Recursive,
                                       bool DefinitionRequired,
                                       bool AtEndOfTU) {
if (Function->isInvalidDecl() || isa<CXXDeductionGuideDecl>(Function))
  return;

// Never instantiate an explicit specialization except if it is a class scope
// explicit specialization.
TemplateSpecializationKind TSK =
    Function->getTemplateSpecializationKindForInstantiation();
if (TSK == TSK_ExplicitSpecialization)
  return;

// Don't instantiate a definition if we already have one.
const FunctionDecl *ExistingDefn = nullptr;
if (Function->isDefined(ExistingDefn,
                        /*CheckForPendingFriendDefinition=*/true)) {
  if (ExistingDefn->isThisDeclarationADefinition())
    return;

  // If we're asked to instantiate a function whose body comes from an
  // instantiated friend declaration, attach the instantiated body to the
  // corresponding declaration of the function.
  assert(ExistingDefn->isThisDeclarationInstantiatedFromAFriendDefinition())((void)0);
  Function = const_cast<FunctionDecl*>(ExistingDefn);
}

// Find the function body that we'll be substituting.
const FunctionDecl *PatternDecl = Function->getTemplateInstantiationPattern();
assert(PatternDecl && "instantiating a non-template")((void)0);

const FunctionDecl *PatternDef = PatternDecl->getDefinition();
Stmt *Pattern = nullptr;
if (PatternDef) {
  Pattern = PatternDef->getBody(PatternDef);
  PatternDecl = PatternDef;
  if (PatternDef->willHaveBody())
    PatternDef = nullptr;
}

// FIXME: We need to track the instantiation stack in order to know which
// definitions should be visible within this instantiation.
if (DiagnoseUninstantiableTemplate(PointOfInstantiation, Function,
                              Function->getInstantiatedFromMemberFunction(),
                                   PatternDecl, PatternDef, TSK,
                                   /*Complain*/DefinitionRequired)) {
  if (DefinitionRequired)
    Function->setInvalidDecl();
  else if (TSK == TSK_ExplicitInstantiationDefinition) {
    // Try again at the end of the translation unit (at which point a
    // definition will be required).
    assert(!Recursive)((void)0);
    Function->setInstantiationIsPending(true);
    PendingInstantiations.push_back(
      std::make_pair(Function, PointOfInstantiation));
  } else if (TSK == TSK_ImplicitInstantiation) {
    if (AtEndOfTU && !getDiagnostics().hasErrorOccurred() &&
        !getSourceManager().isInSystemHeader(PatternDecl->getBeginLoc())) {
      Diag(PointOfInstantiation, diag::warn_func_template_missing)
        << Function;
      Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
      if (getLangOpts().CPlusPlus11)
        Diag(PointOfInstantiation, diag::note_inst_declaration_hint)
          << Function;
    }
  }

  return;
}

// Postpone late parsed template instantiations.
if (PatternDecl->isLateTemplateParsed() &&
    !LateTemplateParser) {
  Function->setInstantiationIsPending(true);
  LateParsedInstantiations.push_back(
      std::make_pair(Function, PointOfInstantiation));
  return;
}

llvm::TimeTraceScope TimeScope("InstantiateFunction", [&]() {
  std::string Name;
  llvm::raw_string_ostream OS(Name);
  Function->getNameForDiagnostic(OS, getPrintingPolicy(),
                                 /*Qualified=*/true);
  return Name;
});

// If we're performing recursive template instantiation, create our own
// queue of pending implicit instantiations that we will instantiate later,
// while we're still within our own instantiation context.
// This has to happen before LateTemplateParser below is called, so that
// it marks vtables used in late parsed templates as used.
GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                   /*Enabled=*/Recursive);
LocalEagerInstantiationScope LocalInstantiations(*this);

// Call the LateTemplateParser callback if there is a need to late parse
// a templated function definition.
if (!Pattern && PatternDecl->isLateTemplateParsed() &&
    LateTemplateParser) {
  // FIXME: Optimize to allow individual templates to be deserialized.
  if (PatternDecl->isFromASTFile())
    ExternalSource->ReadLateParsedTemplates(LateParsedTemplateMap);

  auto LPTIter = LateParsedTemplateMap.find(PatternDecl);
  assert(LPTIter != LateParsedTemplateMap.end() &&((void)0)
         "missing LateParsedTemplate")((void)0);
  LateTemplateParser(OpaqueParser, *LPTIter->second);
  Pattern = PatternDecl->getBody(PatternDecl);
}

// Note, we should never try to instantiate a deleted function template.
assert((Pattern || PatternDecl->isDefaulted() ||((void)0)
        PatternDecl->hasSkippedBody()) &&((void)0)
       "unexpected kind of function template definition")((void)0);

// C++1y [temp.explicit]p10:
//   Except for inline functions, declarations with types deduced from their
//   initializer or return value, and class template specializations, other
//   explicit instantiation declarations have the effect of suppressing the
//   implicit instantiation of the entity to which they refer.
if (TSK == TSK_ExplicitInstantiationDeclaration &&
    !PatternDecl->isInlined() &&
    !PatternDecl->getReturnType()->getContainedAutoType())
  return;

if (PatternDecl->isInlined()) {
  // Function, and all later redeclarations of it (from imported modules,
  // for instance), are now implicitly inline.
  for (auto *D = Function->getMostRecentDecl(); /**/;
       D = D->getPreviousDecl()) {
    D->setImplicitlyInline();
    if (D == Function)
      break;
  }
}

InstantiatingTemplate Inst(*this, PointOfInstantiation, Function);
if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
  return;
PrettyDeclStackTraceEntry CrashInfo(Context, Function, SourceLocation(),
                                    "instantiating function definition");

// The instantiation is visible here, even if it was first declared in an
// unimported module.
Function->setVisibleDespiteOwningModule();

// Copy the inner loc start from the pattern.
Function->setInnerLocStart(PatternDecl->getInnerLocStart());

EnterExpressionEvaluationContext EvalContext(
    *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);

// Introduce a new scope where local variable instantiations will be
// recorded, unless we're actually a member function within a local
// class, in which case we need to merge our results with the parent
// scope (of the enclosing function). The exception is instantiating
// a function template specialization, since the template to be
// instantiated already has references to locals properly substituted.
bool MergeWithParentScope = false;
if (CXXRecordDecl *Rec = dyn_cast<CXXRecordDecl>(Function->getDeclContext()))
  MergeWithParentScope =
      Rec->isLocalClass() && !Function->isFunctionTemplateSpecialization();

LocalInstantiationScope Scope(*this, MergeWithParentScope);
auto RebuildTypeSourceInfoForDefaultSpecialMembers = [&]() {
  // Special members might get their TypeSourceInfo set up w.r.t the
  // PatternDecl context, in which case parameters could still be pointing
  // back to the original class, make sure arguments are bound to the
  // instantiated record instead.
  assert(PatternDecl->isDefaulted() &&((void)0)
         "Special member needs to be defaulted")((void)0);
  auto PatternSM = getDefaultedFunctionKind(PatternDecl).asSpecialMember();
  if (!(PatternSM == Sema::CXXCopyConstructor ||
        PatternSM == Sema::CXXCopyAssignment ||
        PatternSM == Sema::CXXMoveConstructor ||
        PatternSM == Sema::CXXMoveAssignment))
    return;

  auto *NewRec = dyn_cast<CXXRecordDecl>(Function->getDeclContext());
  const auto *PatternRec =
      dyn_cast<CXXRecordDecl>(PatternDecl->getDeclContext());
  if (!NewRec || !PatternRec)
    return;
  if (!PatternRec->isLambda())
    return;

  struct SpecialMemberTypeInfoRebuilder
      : TreeTransform<SpecialMemberTypeInfoRebuilder> {
    using Base = TreeTransform<SpecialMemberTypeInfoRebuilder>;
    const CXXRecordDecl *OldDecl;
    CXXRecordDecl *NewDecl;

    SpecialMemberTypeInfoRebuilder(Sema &SemaRef, const CXXRecordDecl *O,
                                   CXXRecordDecl *N)
        : TreeTransform(SemaRef), OldDecl(O), NewDecl(N) {}

    bool TransformExceptionSpec(SourceLocation Loc,
                                FunctionProtoType::ExceptionSpecInfo &ESI,
                                SmallVectorImpl<QualType> &Exceptions,
                                bool &Changed) {
      return false;
    }

    QualType TransformRecordType(TypeLocBuilder &TLB, RecordTypeLoc TL) {
      const RecordType *T = TL.getTypePtr();
      RecordDecl *Record = cast_or_null<RecordDecl>(
          getDerived().TransformDecl(TL.getNameLoc(), T->getDecl()));
      if (Record != OldDecl)
        return Base::TransformRecordType(TLB, TL);

      QualType Result = getDerived().RebuildRecordType(NewDecl);
      if (Result.isNull())
        return QualType();

      RecordTypeLoc NewTL = TLB.push<RecordTypeLoc>(Result);
      NewTL.setNameLoc(TL.getNameLoc());
      return Result;
    }
  } IR{*this, PatternRec, NewRec};

  TypeSourceInfo *NewSI = IR.TransformType(Function->getTypeSourceInfo());
  Function->setType(NewSI->getType());
  Function->setTypeSourceInfo(NewSI);

  ParmVarDecl *Parm = Function->getParamDecl(0);
  TypeSourceInfo *NewParmSI = IR.TransformType(Parm->getTypeSourceInfo());
  Parm->setType(NewParmSI->getType());
  Parm->setTypeSourceInfo(NewParmSI);
};

if (PatternDecl->isDefaulted()) {
  RebuildTypeSourceInfoForDefaultSpecialMembers();
  SetDeclDefaulted(Function, PatternDecl->getLocation());
} else {
  MultiLevelTemplateArgumentList TemplateArgs =
    getTemplateInstantiationArgs(Function, nullptr, false, PatternDecl);

  // Substitute into the qualifier; we can get a substitution failure here
  // through evil use of alias templates.
  // FIXME: Is CurContext correct for this? Should we go to the (instantiation
  // of the) lexical context of the pattern?
  SubstQualifier(*this, PatternDecl, Function, TemplateArgs);

  ActOnStartOfFunctionDef(nullptr, Function);

  // Enter the scope of this instantiation. We don't use
  // PushDeclContext because we don't have a scope.
  Sema::ContextRAII savedContext(*this, Function);

  if (addInstantiatedParametersToScope(*this, Function, PatternDecl, Scope,
                                       TemplateArgs))
    return;

  StmtResult Body;
  if (PatternDecl->hasSkippedBody()) {
    ActOnSkippedFunctionBody(Function);
    Body = nullptr;
  } else {
    if (CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(Function)) {
      // If this is a constructor, instantiate the member initializers.
      InstantiateMemInitializers(Ctor, cast<CXXConstructorDecl>(PatternDecl),
                                 TemplateArgs);

      // If this is an MS ABI dllexport default constructor, instantiate any
      // default arguments.
      if (Context.getTargetInfo().getCXXABI().isMicrosoft() &&
          Ctor->isDefaultConstructor()) {
        InstantiateDefaultCtorDefaultArgs(Ctor);
      }
    }

    // Instantiate the function body.
    Body = SubstStmt(Pattern, TemplateArgs);

    if (Body.isInvalid())
      Function->setInvalidDecl();
  }
  // FIXME: finishing the function body while in an expression evaluation
  // context seems wrong. Investigate more.
  ActOnFinishFunctionBody(Function, Body.get(), /*IsInstantiation=*/true);

  PerformDependentDiagnostics(PatternDecl, TemplateArgs);

  if (auto *Listener = getASTMutationListener())
    Listener->FunctionDefinitionInstantiated(Function);

  savedContext.pop();
}

DeclGroupRef DG(Function);
Consumer.HandleTopLevelDecl(DG);

// This class may have local implicit instantiations that need to be
// instantiation within this scope.
LocalInstantiations.perform();
Scope.Exit();
GlobalInstantiations.perform();
5080}

5082VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
  VarTemplateDecl *VarTemplate, VarDecl *FromVar,
  const TemplateArgumentList &TemplateArgList,
  const TemplateArgumentListInfo &TemplateArgsInfo,
  SmallVectorImpl<TemplateArgument> &Converted,
  SourceLocation PointOfInstantiation,
  LateInstantiatedAttrVec *LateAttrs,
  LocalInstantiationScope *StartingScope) {
if (FromVar->isInvalidDecl())
  return nullptr;

InstantiatingTemplate Inst(*this, PointOfInstantiation, FromVar);
if (Inst.isInvalid())
  return nullptr;

MultiLevelTemplateArgumentList TemplateArgLists;
TemplateArgLists.addOuterTemplateArguments(&TemplateArgList);

// Instantiate the first declaration of the variable template: for a partial
// specialization of a static data member template, the first declaration may
// or may not be the declaration in the class; if it's in the class, we want
// to instantiate a member in the class (a declaration), and if it's outside,
// we want to instantiate a definition.
//
// If we're instantiating an explicitly-specialized member template or member
// partial specialization, don't do this. The member specialization completely
// replaces the original declaration in this case.
bool IsMemberSpec = false;
if (VarTemplatePartialSpecializationDecl *PartialSpec =
        dyn_cast<VarTemplatePartialSpecializationDecl>(FromVar))
  IsMemberSpec = PartialSpec->isMemberSpecialization();
else if (VarTemplateDecl *FromTemplate = FromVar->getDescribedVarTemplate())
  IsMemberSpec = FromTemplate->isMemberSpecialization();
if (!IsMemberSpec)
  FromVar = FromVar->getFirstDecl();

MultiLevelTemplateArgumentList MultiLevelList(TemplateArgList);
TemplateDeclInstantiator Instantiator(*this, FromVar->getDeclContext(),
                                      MultiLevelList);

// TODO: Set LateAttrs and StartingScope ...

return cast_or_null<VarTemplateSpecializationDecl>(
    Instantiator.VisitVarTemplateSpecializationDecl(
        VarTemplate, FromVar, TemplateArgsInfo, Converted));
5127}

5129/// Instantiates a variable template specialization by completing it
5130/// with appropriate type information and initializer.
5131VarTemplateSpecializationDecl *Sema::CompleteVarTemplateSpecializationDecl(
  VarTemplateSpecializationDecl *VarSpec, VarDecl *PatternDecl,
  const MultiLevelTemplateArgumentList &TemplateArgs) {
assert(PatternDecl->isThisDeclarationADefinition() &&((void)0)
       "don't have a definition to instantiate from")((void)0);

// Do substitution on the type of the declaration
TypeSourceInfo *DI =
    SubstType(PatternDecl->getTypeSourceInfo(), TemplateArgs,
              PatternDecl->getTypeSpecStartLoc(), PatternDecl->getDeclName());
if (!DI)
  return nullptr;

// Update the type of this variable template specialization.
VarSpec->setType(DI->getType());

// Convert the declaration into a definition now.
VarSpec->setCompleteDefinition();

// Instantiate the initializer.
InstantiateVariableInitializer(VarSpec, PatternDecl, TemplateArgs);

if (getLangOpts().OpenCL)
  deduceOpenCLAddressSpace(VarSpec);

return VarSpec;
5157}

5159/// BuildVariableInstantiation - Used after a new variable has been created.
5160/// Sets basic variable data and decides whether to postpone the
5161/// variable instantiation.
5162void Sema::BuildVariableInstantiation(
  VarDecl *NewVar, VarDecl *OldVar,
  const MultiLevelTemplateArgumentList &TemplateArgs,
  LateInstantiatedAttrVec *LateAttrs, DeclContext *Owner,
  LocalInstantiationScope *StartingScope,
  bool InstantiatingVarTemplate,
  VarTemplateSpecializationDecl *PrevDeclForVarTemplateSpecialization) {
// Instantiating a partial specialization to produce a partial
// specialization.
bool InstantiatingVarTemplatePartialSpec =
    isa<VarTemplatePartialSpecializationDecl>(OldVar) &&
    isa<VarTemplatePartialSpecializationDecl>(NewVar);
// Instantiating from a variable template (or partial specialization) to
// produce a variable template specialization.
bool InstantiatingSpecFromTemplate =
    isa<VarTemplateSpecializationDecl>(NewVar) &&
    (OldVar->getDescribedVarTemplate() ||
     isa<VarTemplatePartialSpecializationDecl>(OldVar));

// If we are instantiating a local extern declaration, the
// instantiation belongs lexically to the containing function.
// If we are instantiating a static data member defined
// out-of-line, the instantiation will have the same lexical
// context (which will be a namespace scope) as the template.
if (OldVar->isLocalExternDecl()) {
  NewVar->setLocalExternDecl();
  NewVar->setLexicalDeclContext(Owner);
} else if (OldVar->isOutOfLine())
  NewVar->setLexicalDeclContext(OldVar->getLexicalDeclContext());
NewVar->setTSCSpec(OldVar->getTSCSpec());
NewVar->setInitStyle(OldVar->getInitStyle());
NewVar->setCXXForRangeDecl(OldVar->isCXXForRangeDecl());
NewVar->setObjCForDecl(OldVar->isObjCForDecl());
NewVar->setConstexpr(OldVar->isConstexpr());
NewVar->setInitCapture(OldVar->isInitCapture());
NewVar->setPreviousDeclInSameBlockScope(
    OldVar->isPreviousDeclInSameBlockScope());
NewVar->setAccess(OldVar->getAccess());

if (!OldVar->isStaticDataMember()) {
  if (OldVar->isUsed(false))
    NewVar->setIsUsed();
  NewVar->setReferenced(OldVar->isReferenced());
}

InstantiateAttrs(TemplateArgs, OldVar, NewVar, LateAttrs, StartingScope);

LookupResult Previous(
    *this, NewVar->getDeclName(), NewVar->getLocation(),
    NewVar->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
                                : Sema::LookupOrdinaryName,
    NewVar->isLocalExternDecl() ? Sema::ForExternalRedeclaration
                                : forRedeclarationInCurContext());

if (NewVar->isLocalExternDecl() && OldVar->getPreviousDecl() &&
    (!OldVar->getPreviousDecl()->getDeclContext()->isDependentContext() ||
     OldVar->getPreviousDecl()->getDeclContext()==OldVar->getDeclContext())) {
  // We have a previous declaration. Use that one, so we merge with the
  // right type.
  if (NamedDecl *NewPrev = FindInstantiatedDecl(
          NewVar->getLocation(), OldVar->getPreviousDecl(), TemplateArgs))
    Previous.addDecl(NewPrev);
} else if (!isa<VarTemplateSpecializationDecl>(NewVar) &&
           OldVar->hasLinkage()) {
  LookupQualifiedName(Previous, NewVar->getDeclContext(), false);
} else if (PrevDeclForVarTemplateSpecialization) {
  Previous.addDecl(PrevDeclForVarTemplateSpecialization);
}
CheckVariableDeclaration(NewVar, Previous);

if (!InstantiatingVarTemplate) {
  NewVar->getLexicalDeclContext()->addHiddenDecl(NewVar);
  if (!NewVar->isLocalExternDecl() || !NewVar->getPreviousDecl())
    NewVar->getDeclContext()->makeDeclVisibleInContext(NewVar);
}

if (!OldVar->isOutOfLine()) {
  if (NewVar->getDeclContext()->isFunctionOrMethod())
    CurrentInstantiationScope->InstantiatedLocal(OldVar, NewVar);
}

// Link instantiations of static data members back to the template from
// which they were instantiated.
//
// Don't do this when instantiating a template (we link the template itself
// back in that case) nor when instantiating a static data member template
// (that's not a member specialization).
if (NewVar->isStaticDataMember() && !InstantiatingVarTemplate &&
    !InstantiatingSpecFromTemplate)
  NewVar->setInstantiationOfStaticDataMember(OldVar,
                                             TSK_ImplicitInstantiation);

// If the pattern is an (in-class) explicit specialization, then the result
// is also an explicit specialization.
if (VarTemplateSpecializationDecl *OldVTSD =
        dyn_cast<VarTemplateSpecializationDecl>(OldVar)) {
  if (OldVTSD->getSpecializationKind() == TSK_ExplicitSpecialization &&
      !isa<VarTemplatePartialSpecializationDecl>(OldVTSD))
    cast<VarTemplateSpecializationDecl>(NewVar)->setSpecializationKind(
        TSK_ExplicitSpecialization);
}

// Forward the mangling number from the template to the instantiated decl.
Context.setManglingNumber(NewVar, Context.getManglingNumber(OldVar));
Context.setStaticLocalNumber(NewVar, Context.getStaticLocalNumber(OldVar));

// Figure out whether to eagerly instantiate the initializer.
if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
  // We're producing a template. Don't instantiate the initializer yet.
} else if (NewVar->getType()->isUndeducedType()) {
  // We need the type to complete the declaration of the variable.
  InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
} else if (InstantiatingSpecFromTemplate ||
           (OldVar->isInline() && OldVar->isThisDeclarationADefinition() &&
            !NewVar->isThisDeclarationADefinition())) {
  // Delay instantiation of the initializer for variable template
  // specializations or inline static data members until a definition of the
  // variable is needed.
} else {
  InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
}

// Diagnose unused local variables with dependent types, where the diagnostic
// will have been deferred.
if (!NewVar->isInvalidDecl() &&
    NewVar->getDeclContext()->isFunctionOrMethod() &&
    OldVar->getType()->isDependentType())
  DiagnoseUnusedDecl(NewVar);
5290}

5292/// Instantiate the initializer of a variable.
5293void Sema::InstantiateVariableInitializer(
  VarDecl *Var, VarDecl *OldVar,
  const MultiLevelTemplateArgumentList &TemplateArgs) {
if (ASTMutationListener *L = getASTContext().getASTMutationListener())
  L->VariableDefinitionInstantiated(Var);

// We propagate the 'inline' flag with the initializer, because it
// would otherwise imply that the variable is a definition for a
// non-static data member.
if (OldVar->isInlineSpecified())
  Var->setInlineSpecified();
else if (OldVar->isInline())
  Var->setImplicitlyInline();

if (OldVar->getInit()) {
  EnterExpressionEvaluationContext Evaluated(
      *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated, Var);

  // Instantiate the initializer.
  ExprResult Init;

  {
    ContextRAII SwitchContext(*this, Var->getDeclContext());
    Init = SubstInitializer(OldVar->getInit(), TemplateArgs,
                            OldVar->getInitStyle() == VarDecl::CallInit);
  }

  if (!Init.isInvalid()) {
    Expr *InitExpr = Init.get();

    if (Var->hasAttr<DLLImportAttr>() &&
        (!InitExpr ||
         !InitExpr->isConstantInitializer(getASTContext(), false))) {
      // Do not dynamically initialize dllimport variables.
    } else if (InitExpr) {
      bool DirectInit = OldVar->isDirectInit();
      AddInitializerToDecl(Var, InitExpr, DirectInit);
    } else
      ActOnUninitializedDecl(Var);
  } else {
    // FIXME: Not too happy about invalidating the declaration
    // because of a bogus initializer.
    Var->setInvalidDecl();
  }
} else {
  // `inline` variables are a definition and declaration all in one; we won't
  // pick up an initializer from anywhere else.
  if (Var->isStaticDataMember() && !Var->isInline()) {
    if (!Var->isOutOfLine())
      return;

    // If the declaration inside the class had an initializer, don't add
    // another one to the out-of-line definition.
    if (OldVar->getFirstDecl()->hasInit())
      return;
  }

  // We'll add an initializer to a for-range declaration later.
  if (Var->isCXXForRangeDecl() || Var->isObjCForDecl())
    return;

  ActOnUninitializedDecl(Var);
}

if (getLangOpts().CUDA)
  checkAllowedCUDAInitializer(Var);
5359}

5361/// Instantiate the definition of the given variable from its
5362/// template.
5363///
5364/// \param PointOfInstantiation the point at which the instantiation was
5365/// required. Note that this is not precisely a "point of instantiation"
5366/// for the variable, but it's close.
5367///
5368/// \param Var the already-instantiated declaration of a templated variable.
5369///
5370/// \param Recursive if true, recursively instantiates any functions that
5371/// are required by this instantiation.
5372///
5373/// \param DefinitionRequired if true, then we are performing an explicit
5374/// instantiation where a definition of the variable is required. Complain
5375/// if there is no such definition.
5376void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
                                       VarDecl *Var, bool Recursive,
                                    bool DefinitionRequired, bool AtEndOfTU) {
if (Var->isInvalidDecl())
  return;

// Never instantiate an explicitly-specialized entity.
TemplateSpecializationKind TSK =
    Var->getTemplateSpecializationKindForInstantiation();
if (TSK == TSK_ExplicitSpecialization)
  return;

// Find the pattern and the arguments to substitute into it.
VarDecl *PatternDecl = Var->getTemplateInstantiationPattern();
assert(PatternDecl && "no pattern for templated variable")((void)0);
MultiLevelTemplateArgumentList TemplateArgs =
    getTemplateInstantiationArgs(Var);

VarTemplateSpecializationDecl *VarSpec =
    dyn_cast<VarTemplateSpecializationDecl>(Var);
if (VarSpec) {
  // If this is a static data member template, there might be an
  // uninstantiated initializer on the declaration. If so, instantiate
  // it now.
  //
  // FIXME: This largely duplicates what we would do below. The difference
  // is that along this path we may instantiate an initializer from an
  // in-class declaration of the template and instantiate the definition
  // from a separate out-of-class definition.
  if (PatternDecl->isStaticDataMember() &&
      (PatternDecl = PatternDecl->getFirstDecl())->hasInit() &&
      !Var->hasInit()) {
    // FIXME: Factor out the duplicated instantiation context setup/tear down
    // code here.
    InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
    if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
      return;
    PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                        "instantiating variable initializer");

    // The instantiation is visible here, even if it was first declared in an
    // unimported module.
    Var->setVisibleDespiteOwningModule();

    // If we're performing recursive template instantiation, create our own
    // queue of pending implicit instantiations that we will instantiate
    // later, while we're still within our own instantiation context.
    GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                       /*Enabled=*/Recursive);
    LocalInstantiationScope Local(*this);
    LocalEagerInstantiationScope LocalInstantiations(*this);

    // Enter the scope of this instantiation. We don't use
    // PushDeclContext because we don't have a scope.
    ContextRAII PreviousContext(*this, Var->getDeclContext());
    InstantiateVariableInitializer(Var, PatternDecl, TemplateArgs);
    PreviousContext.pop();

    // This variable may have local implicit instantiations that need to be
    // instantiated within this scope.
    LocalInstantiations.perform();
    Local.Exit();
    GlobalInstantiations.perform();
  }
} else {
  assert(Var->isStaticDataMember() && PatternDecl->isStaticDataMember() &&((void)0)
         "not a static data member?")((void)0);
}

VarDecl *Def = PatternDecl->getDefinition(getASTContext());

// If we don't have a definition of the variable template, we won't perform
// any instantiation. Rather, we rely on the user to instantiate this
// definition (or provide a specialization for it) in another translation
// unit.
if (!Def && !DefinitionRequired) {
  if (TSK == TSK_ExplicitInstantiationDefinition) {
    PendingInstantiations.push_back(
      std::make_pair(Var, PointOfInstantiation));
  } else if (TSK == TSK_ImplicitInstantiation) {
    // Warn about missing definition at the end of translation unit.
    if (AtEndOfTU && !getDiagnostics().hasErrorOccurred() &&
        !getSourceManager().isInSystemHeader(PatternDecl->getBeginLoc())) {
      Diag(PointOfInstantiation, diag::warn_var_template_missing)
        << Var;
      Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
      if (getLangOpts().CPlusPlus11)
        Diag(PointOfInstantiation, diag::note_inst_declaration_hint) << Var;
    }
    return;
  }
}

// FIXME: We need to track the instantiation stack in order to know which
// definitions should be visible within this instantiation.
// FIXME: Produce diagnostics when Var->getInstantiatedFromStaticDataMember().
if (DiagnoseUninstantiableTemplate(PointOfInstantiation, Var,
                                   /*InstantiatedFromMember*/false,
                                   PatternDecl, Def, TSK,
                                   /*Complain*/DefinitionRequired))
  return;

// C++11 [temp.explicit]p10:
//   Except for inline functions, const variables of literal types, variables
//   of reference types, [...] explicit instantiation declarations
//   have the effect of suppressing the implicit instantiation of the entity
//   to which they refer.
//
// FIXME: That's not exactly the same as "might be usable in constant
// expressions", which only allows constexpr variables and const integral
// types, not arbitrary const literal types.
if (TSK == TSK_ExplicitInstantiationDeclaration &&
    !Var->mightBeUsableInConstantExpressions(getASTContext()))
  return;

// Make sure to pass the instantiated variable to the consumer at the end.
struct PassToConsumerRAII {
  ASTConsumer &Consumer;
  VarDecl *Var;

  PassToConsumerRAII(ASTConsumer &Consumer, VarDecl *Var)
    : Consumer(Consumer), Var(Var) { }

  ~PassToConsumerRAII() {
    Consumer.HandleCXXStaticMemberVarInstantiation(Var);
  }
} PassToConsumerRAII(Consumer, Var);

// If we already have a definition, we're done.
if (VarDecl *Def = Var->getDefinition()) {
  // We may be explicitly instantiating something we've already implicitly
  // instantiated.
  Def->setTemplateSpecializationKind(Var->getTemplateSpecializationKind(),
                                     PointOfInstantiation);
  return;
}

InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
  return;
PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                    "instantiating variable definition");

// If we're performing recursive template instantiation, create our own
// queue of pending implicit instantiations that we will instantiate later,
// while we're still within our own instantiation context.
GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                   /*Enabled=*/Recursive);

// Enter the scope of this instantiation. We don't use
// PushDeclContext because we don't have a scope.
ContextRAII PreviousContext(*this, Var->getDeclContext());
LocalInstantiationScope Local(*this);

LocalEagerInstantiationScope LocalInstantiations(*this);

VarDecl *OldVar = Var;
if (Def->isStaticDataMember() && !Def->isOutOfLine()) {
  // We're instantiating an inline static data member whose definition was
  // provided inside the class.
  InstantiateVariableInitializer(Var, Def, TemplateArgs);
} else if (!VarSpec) {
  Var = cast_or_null<VarDecl>(SubstDecl(Def, Var->getDeclContext(),
                                        TemplateArgs));
} else if (Var->isStaticDataMember() &&
           Var->getLexicalDeclContext()->isRecord()) {
  // We need to instantiate the definition of a static data member template,
  // and all we have is the in-class declaration of it. Instantiate a separate
  // declaration of the definition.
  TemplateDeclInstantiator Instantiator(*this, Var->getDeclContext(),
                                        TemplateArgs);
  Var = cast_or_null<VarDecl>(Instantiator.VisitVarTemplateSpecializationDecl(
      VarSpec->getSpecializedTemplate(), Def, VarSpec->getTemplateArgsInfo(),
      VarSpec->getTemplateArgs().asArray(), VarSpec));
  if (Var) {
    llvm::PointerUnion<VarTemplateDecl *,
                       VarTemplatePartialSpecializationDecl *> PatternPtr =
        VarSpec->getSpecializedTemplateOrPartial();
    if (VarTemplatePartialSpecializationDecl *Partial =
        PatternPtr.dyn_cast<VarTemplatePartialSpecializationDecl *>())
      cast<VarTemplateSpecializationDecl>(Var)->setInstantiationOf(
          Partial, &VarSpec->getTemplateInstantiationArgs());

    // Attach the initializer.
    InstantiateVariableInitializer(Var, Def, TemplateArgs);
  }
} else
  // Complete the existing variable's definition with an appropriately
  // substituted type and initializer.
  Var = CompleteVarTemplateSpecializationDecl(VarSpec, Def, TemplateArgs);

PreviousContext.pop();

if (Var) {
  PassToConsumerRAII.Var = Var;
  Var->setTemplateSpecializationKind(OldVar->getTemplateSpecializationKind(),
                                     OldVar->getPointOfInstantiation());
}

// This variable may have local implicit instantiations that need to be
// instantiated within this scope.
LocalInstantiations.perform();
Local.Exit();
GlobalInstantiations.perform();
5580}

5582void
5583Sema::InstantiateMemInitializers(CXXConstructorDecl *New,
                               const CXXConstructorDecl *Tmpl,
                         const MultiLevelTemplateArgumentList &TemplateArgs) {

SmallVector<CXXCtorInitializer*, 4> NewInits;
bool AnyErrors = Tmpl->isInvalidDecl();

// Instantiate all the initializers.
for (const auto *Init : Tmpl->inits()) {
  // Only instantiate written initializers, let Sema re-construct implicit
  // ones.
  if (!Init->isWritten())
    continue;

  SourceLocation EllipsisLoc;

  if (Init->isPackExpansion()) {
    // This is a pack expansion. We should expand it now.
    TypeLoc BaseTL = Init->getTypeSourceInfo()->getTypeLoc();
    SmallVector<UnexpandedParameterPack, 4> Unexpanded;
    collectUnexpandedParameterPacks(BaseTL, Unexpanded);
    collectUnexpandedParameterPacks(Init->getInit(), Unexpanded);
    bool ShouldExpand = false;
    bool RetainExpansion = false;
    Optional<unsigned> NumExpansions;
    if (CheckParameterPacksForExpansion(Init->getEllipsisLoc(),
                                        BaseTL.getSourceRange(),
                                        Unexpanded,
                                        TemplateArgs, ShouldExpand,
                                        RetainExpansion,
                                        NumExpansions)) {
      AnyErrors = true;
      New->setInvalidDecl();
      continue;
    }
    assert(ShouldExpand && "Partial instantiation of base initializer?")((void)0);

    // Loop over all of the arguments in the argument pack(s),
    for (unsigned I = 0; I != *NumExpansions; ++I) {
      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, I);

      // Instantiate the initializer.
      ExprResult TempInit = SubstInitializer(Init->getInit(), TemplateArgs,
                                             /*CXXDirectInit=*/true);
      if (TempInit.isInvalid()) {
        AnyErrors = true;
        break;
      }

      // Instantiate the base type.
      TypeSourceInfo *BaseTInfo = SubstType(Init->getTypeSourceInfo(),
                                            TemplateArgs,
                                            Init->getSourceLocation(),
                                            New->getDeclName());
      if (!BaseTInfo) {
        AnyErrors = true;
        break;
      }

      // Build the initializer.
      MemInitResult NewInit = BuildBaseInitializer(BaseTInfo->getType(),
                                                   BaseTInfo, TempInit.get(),
                                                   New->getParent(),
                                                   SourceLocation());
      if (NewInit.isInvalid()) {
        AnyErrors = true;
        break;
      }

      NewInits.push_back(NewInit.get());
    }

    continue;
  }

  // Instantiate the initializer.
  ExprResult TempInit = SubstInitializer(Init->getInit(), TemplateArgs,
                                         /*CXXDirectInit=*/true);
  if (TempInit.isInvalid()) {
    AnyErrors = true;
    continue;
  }

  MemInitResult NewInit;
  if (Init->isDelegatingInitializer() || Init->isBaseInitializer()) {
    TypeSourceInfo *TInfo = SubstType(Init->getTypeSourceInfo(),
                                      TemplateArgs,
                                      Init->getSourceLocation(),
                                      New->getDeclName());
    if (!TInfo) {
      AnyErrors = true;
      New->setInvalidDecl();
      continue;
    }

    if (Init->isBaseInitializer())
      NewInit = BuildBaseInitializer(TInfo->getType(), TInfo, TempInit.get(),
                                     New->getParent(), EllipsisLoc);
    else
      NewInit = BuildDelegatingInitializer(TInfo, TempInit.get(),
                                cast<CXXRecordDecl>(CurContext->getParent()));
  } else if (Init->isMemberInitializer()) {
    FieldDecl *Member = cast_or_null<FieldDecl>(FindInstantiatedDecl(
                                                   Init->getMemberLocation(),
                                                   Init->getMember(),
                                                   TemplateArgs));
    if (!Member) {
      AnyErrors = true;
      New->setInvalidDecl();
      continue;
    }

    NewInit = BuildMemberInitializer(Member, TempInit.get(),
                                     Init->getSourceLocation());
  } else if (Init->isIndirectMemberInitializer()) {
    IndirectFieldDecl *IndirectMember =
       cast_or_null<IndirectFieldDecl>(FindInstantiatedDecl(
                               Init->getMemberLocation(),
                               Init->getIndirectMember(), TemplateArgs));

    if (!IndirectMember) {
      AnyErrors = true;
      New->setInvalidDecl();
      continue;
    }

    NewInit = BuildMemberInitializer(IndirectMember, TempInit.get(),
                                     Init->getSourceLocation());
  }

  if (NewInit.isInvalid()) {
    AnyErrors = true;
    New->setInvalidDecl();
  } else {
    NewInits.push_back(NewInit.get());
  }
}

// Assign all the initializers to the new constructor.
ActOnMemInitializers(New,
                     /*FIXME: ColonLoc */
                     SourceLocation(),
                     NewInits,
                     AnyErrors);
5727}

5729// TODO: this could be templated if the various decl types used the
5730// same method name.
5731static bool isInstantiationOf(ClassTemplateDecl *Pattern,
                            ClassTemplateDecl *Instance) {
Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromMemberTemplate();
} while (Instance);

return false;
5742}

5744static bool isInstantiationOf(FunctionTemplateDecl *Pattern,
                            FunctionTemplateDecl *Instance) {
Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromMemberTemplate();
} while (Instance);

return false;
5755}

5757static bool
5758isInstantiationOf(ClassTemplatePartialSpecializationDecl *Pattern,
                ClassTemplatePartialSpecializationDecl *Instance) {
Pattern
  = cast<ClassTemplatePartialSpecializationDecl>(Pattern->getCanonicalDecl());
do {
  Instance = cast<ClassTemplatePartialSpecializationDecl>(
                                              Instance->getCanonicalDecl());
  if (Pattern == Instance)
    return true;
  Instance = Instance->getInstantiatedFromMember();
} while (Instance);

return false;
5771}

5773static bool isInstantiationOf(CXXRecordDecl *Pattern,
                            CXXRecordDecl *Instance) {
Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromMemberClass();
} while (Instance);

return false;
5784}

5786static bool isInstantiationOf(FunctionDecl *Pattern,
                            FunctionDecl *Instance) {
Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromMemberFunction();
} while (Instance);

return false;
5797}

5799static bool isInstantiationOf(EnumDecl *Pattern,
                            EnumDecl *Instance) {
Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromMemberEnum();
} while (Instance);

return false;
5810}

5812static bool isInstantiationOf(UsingShadowDecl *Pattern,
                            UsingShadowDecl *Instance,
                            ASTContext &C) {
return declaresSameEntity(C.getInstantiatedFromUsingShadowDecl(Instance),
                          Pattern);
5817}

5819static bool isInstantiationOf(UsingDecl *Pattern, UsingDecl *Instance,
                            ASTContext &C) {
return declaresSameEntity(C.getInstantiatedFromUsingDecl(Instance), Pattern);
5822}

5824template<typename T>
5825static bool isInstantiationOfUnresolvedUsingDecl(T *Pattern, Decl *Other,
                                               ASTContext &Ctx) {
// An unresolved using declaration can instantiate to an unresolved using
// declaration, or to a using declaration or a using declaration pack.
//
// Multiple declarations can claim to be instantiated from an unresolved
// using declaration if it's a pack expansion. We want the UsingPackDecl
// in that case, not the individual UsingDecls within the pack.
bool OtherIsPackExpansion;
NamedDecl *OtherFrom;
if (auto *OtherUUD = dyn_cast<T>(Other)) {
  OtherIsPackExpansion = OtherUUD->isPackExpansion();
  OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUUD);
} else if (auto *OtherUPD = dyn_cast<UsingPackDecl>(Other)) {
  OtherIsPackExpansion = true;
  OtherFrom = OtherUPD->getInstantiatedFromUsingDecl();
} else if (auto *OtherUD = dyn_cast<UsingDecl>(Other)) {
  OtherIsPackExpansion = false;
  OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUD);
} else {
  return false;
}
return Pattern->isPackExpansion() == OtherIsPackExpansion &&
       declaresSameEntity(OtherFrom, Pattern);
5849}

5851static bool isInstantiationOfStaticDataMember(VarDecl *Pattern,
                                            VarDecl *Instance) {
assert(Instance->isStaticDataMember())((void)0);

Pattern = Pattern->getCanonicalDecl();

do {
  Instance = Instance->getCanonicalDecl();
  if (Pattern == Instance) return true;
  Instance = Instance->getInstantiatedFromStaticDataMember();
} while (Instance);

return false;
5864}

5866// Other is the prospective instantiation
5867// D is the prospective pattern
5868static bool isInstantiationOf(ASTContext &Ctx, NamedDecl *D, Decl *Other) {
if (auto *UUD = dyn_cast<UnresolvedUsingTypenameDecl>(D))
  return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);

if (auto *UUD = dyn_cast<UnresolvedUsingValueDecl>(D))
  return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);

if (D->getKind() != Other->getKind())
  return false;

if (auto *Record = dyn_cast<CXXRecordDecl>(Other))
  return isInstantiationOf(cast<CXXRecordDecl>(D), Record);

if (auto *Function = dyn_cast<FunctionDecl>(Other))
  return isInstantiationOf(cast<FunctionDecl>(D), Function);

if (auto *Enum = dyn_cast<EnumDecl>(Other))
  return isInstantiationOf(cast<EnumDecl>(D), Enum);

if (auto *Var = dyn_cast<VarDecl>(Other))
  if (Var->isStaticDataMember())
    return isInstantiationOfStaticDataMember(cast<VarDecl>(D), Var);

if (auto *Temp = dyn_cast<ClassTemplateDecl>(Other))
  return isInstantiationOf(cast<ClassTemplateDecl>(D), Temp);

if (auto *Temp = dyn_cast<FunctionTemplateDecl>(Other))
  return isInstantiationOf(cast<FunctionTemplateDecl>(D), Temp);

if (auto *PartialSpec =
        dyn_cast<ClassTemplatePartialSpecializationDecl>(Other))
  return isInstantiationOf(cast<ClassTemplatePartialSpecializationDecl>(D),
                           PartialSpec);

if (auto *Field = dyn_cast<FieldDecl>(Other)) {
  if (!Field->getDeclName()) {
    // This is an unnamed field.
    return declaresSameEntity(Ctx.getInstantiatedFromUnnamedFieldDecl(Field),
                              cast<FieldDecl>(D));
  }
}

if (auto *Using = dyn_cast<UsingDecl>(Other))
  return isInstantiationOf(cast<UsingDecl>(D), Using, Ctx);

if (auto *Shadow = dyn_cast<UsingShadowDecl>(Other))
  return isInstantiationOf(cast<UsingShadowDecl>(D), Shadow, Ctx);

return D->getDeclName() &&
       D->getDeclName() == cast<NamedDecl>(Other)->getDeclName();
5918}

5920template<typename ForwardIterator>
5921static NamedDecl *findInstantiationOf(ASTContext &Ctx,
                                    NamedDecl *D,
                                    ForwardIterator first,
                                    ForwardIterator last) {
for (; first != last; ++first)
  if (isInstantiationOf(Ctx, D, *first))
    return cast<NamedDecl>(*first);

return nullptr;
5930}

5932/// Finds the instantiation of the given declaration context
5933/// within the current instantiation.
5934///
5935/// \returns NULL if there was an error
5936DeclContext *Sema::FindInstantiatedContext(SourceLocation Loc, DeclContext* DC,
                        const MultiLevelTemplateArgumentList &TemplateArgs) {
if (NamedDecl *D39.1
'D' is null
1
'D' is null
1
'D' is null
 = dyn_cast<NamedDecl>(DC)) {
39
←
Assuming 'DC' is not a 'NamedDecl'→
40
←
Taking false branch→
  Decl* ID = FindInstantiatedDecl(Loc, D, TemplateArgs, true);
  return cast_or_null<DeclContext>(ID);
} else return DC;
41
←
Returning pointer (loaded from 'DC'), which participates in a condition later→
5942}

5944/// Determine whether the given context is dependent on template parameters at
5945/// level \p Level or below.
5946///
5947/// Sometimes we only substitute an inner set of template arguments and leave
5948/// the outer templates alone. In such cases, contexts dependent only on the
5949/// outer levels are not effectively dependent.
5950static bool isDependentContextAtLevel(DeclContext *DC, unsigned Level) {
if (!DC->isDependentContext())
13
←
Assuming the condition is false→
14
←
Taking false branch→
  return false;
if (!Level)
15
←
Assuming 'Level' is not equal to 0, which participates in a condition later→
16
←
Taking false branch→
  return true;
return cast<Decl>(DC)->getTemplateDepth() > Level;
17
←
'DC' is a 'Decl'→
18
←
Assuming the condition is true→
19
←
Returning the value 1, which participates in a condition later→
5956}

5958/// Find the instantiation of the given declaration within the
5959/// current instantiation.
5960///
5961/// This routine is intended to be used when \p D is a declaration
5962/// referenced from within a template, that needs to mapped into the
5963/// corresponding declaration within an instantiation. For example,
5964/// given:
5965///
5966/// \code
5967/// template<typename T>
5968/// struct X {
5969///   enum Kind {
5970///     KnownValue = sizeof(T)
5971///   };
5972///
5973///   bool getKind() const { return KnownValue; }
5974/// };
5975///
5976/// template struct X<int>;
5977/// \endcode
5978///
5979/// In the instantiation of X<int>::getKind(), we need to map the \p
5980/// EnumConstantDecl for \p KnownValue (which refers to
5981/// X<T>::<Kind>::KnownValue) to its instantiation (X<int>::<Kind>::KnownValue).
5982/// \p FindInstantiatedDecl performs this mapping from within the instantiation
5983/// of X<int>.
5984NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
                        const MultiLevelTemplateArgumentList &TemplateArgs,
                        bool FindingInstantiatedContext) {
DeclContext *ParentDC = D->getDeclContext();
1
Calling 'Decl::getDeclContext'→
11
←
Returning from 'Decl::getDeclContext'→
// Determine whether our parent context depends on any of the tempalte
// arguments we're currently substituting.
bool ParentDependsOnArgs = isDependentContextAtLevel(
12
←
Calling 'isDependentContextAtLevel'→
20
←
Returning from 'isDependentContextAtLevel'→
    ParentDC, TemplateArgs.getNumRetainedOuterLevels());
// FIXME: Parmeters of pointer to functions (y below) that are themselves
// parameters (p below) can have their ParentDC set to the translation-unit
// - thus we can not consistently check if the ParentDC of such a parameter
// is Dependent or/and a FunctionOrMethod.
// For e.g. this code, during Template argument deduction tries to
// find an instantiated decl for (T y) when the ParentDC for y is
// the translation unit.
//   e.g. template <class T> void Foo(auto (*p)(T y) -> decltype(y())) {}
//   float baz(float(*)()) { return 0.0; }
//   Foo(baz);
// The better fix here is perhaps to ensure that a ParmVarDecl, by the time
// it gets here, always has a FunctionOrMethod as its ParentDC??
// For now:
//  - as long as we have a ParmVarDecl whose parent is non-dependent and
//    whose type is not instantiation dependent, do nothing to the decl
//  - otherwise find its instantiated decl.
if (isa<ParmVarDecl>(D) && !ParentDependsOnArgs &&
21
←
Assuming 'D' is not a 'ParmVarDecl'→
22
←
Taking false branch→
    !cast<ParmVarDecl>(D)->getType()->isInstantiationDependentType())
  return D;
if (isa<ParmVarDecl>(D) || isa<NonTypeTemplateParmDecl>(D) ||
23
←
Assuming 'D' is not a 'ParmVarDecl'→
24
←
Assuming 'D' is not a 'NonTypeTemplateParmDecl'→
    isa<TemplateTypeParmDecl>(D) || isa<TemplateTemplateParmDecl>(D) ||
25
←
Assuming 'D' is not a 'TemplateTypeParmDecl'→
26
←
Assuming 'D' is not a 'TemplateTemplateParmDecl'→
    (ParentDependsOnArgs26.1
'ParentDependsOnArgs' is true
1
'ParentDependsOnArgs' is true
1
'ParentDependsOnArgs' is true
 && (ParentDC->isFunctionOrMethod() ||
27
←
Calling 'DeclContext::isFunctionOrMethod'→
31
←
Returning from 'DeclContext::isFunctionOrMethod'→
                             isa<OMPDeclareReductionDecl>(ParentDC) ||
32
←
Assuming 'ParentDC' is not a 'OMPDeclareReductionDecl'→
                             isa<OMPDeclareMapperDecl>(ParentDC))) ||
33
←
Assuming 'ParentDC' is not a 'OMPDeclareMapperDecl'→
    (isa<CXXRecordDecl>(D) && cast<CXXRecordDecl>(D)->isLambda())) {
34
←
Assuming 'D' is not a 'CXXRecordDecl'→
  // D is a local of some kind. Look into the map of local
  // declarations to their instantiations.
  if (CurrentInstantiationScope) {
    if (auto Found = CurrentInstantiationScope->findInstantiationOf(D)) {
      if (Decl *FD = Found->dyn_cast<Decl *>())
        return cast<NamedDecl>(FD);

      int PackIdx = ArgumentPackSubstitutionIndex;
      assert(PackIdx != -1 &&((void)0)
             "found declaration pack but not pack expanding")((void)0);
      typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
      return cast<NamedDecl>((*Found->get<DeclArgumentPack *>())[PackIdx]);
    }
  }

  // If we're performing a partial substitution during template argument
  // deduction, we may not have values for template parameters yet. They
  // just map to themselves.
  if (isa<NonTypeTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
      isa<TemplateTemplateParmDecl>(D))
    return D;

  if (D->isInvalidDecl())
    return nullptr;

  // Normally this function only searches for already instantiated declaration
  // however we have to make an exclusion for local types used before
  // definition as in the code:
  //
  //   template<typename T> void f1() {
  //     void g1(struct x1);
  //     struct x1 {};
  //   }
  //
  // In this case instantiation of the type of 'g1' requires definition of
  // 'x1', which is defined later. Error recovery may produce an enum used
  // before definition. In these cases we need to instantiate relevant
  // declarations here.
  bool NeedInstantiate = false;
  if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D))
    NeedInstantiate = RD->isLocalClass();
  else if (isa<TypedefNameDecl>(D) &&
           isa<CXXDeductionGuideDecl>(D->getDeclContext()))
    NeedInstantiate = true;
  else
    NeedInstantiate = isa<EnumDecl>(D);
  if (NeedInstantiate) {
    Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
    CurrentInstantiationScope->InstantiatedLocal(D, Inst);
    return cast<TypeDecl>(Inst);
  }

  // If we didn't find the decl, then we must have a label decl that hasn't
  // been found yet.  Lazily instantiate it and return it now.
  assert(isa<LabelDecl>(D))((void)0);

  Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
  assert(Inst && "Failed to instantiate label??")((void)0);

  CurrentInstantiationScope->InstantiatedLocal(D, Inst);
  return cast<LabelDecl>(Inst);
}

if (CXXRecordDecl *Record35.1
'Record' is null
1
'Record' is null
1
'Record' is null
 = dyn_cast<CXXRecordDecl>(D)) {
35
←
Assuming 'D' is not a 'CXXRecordDecl'→
36
←
Taking false branch→
  if (!Record->isDependentContext())
    return D;

  // Determine whether this record is the "templated" declaration describing
  // a class template or class template partial specialization.
  ClassTemplateDecl *ClassTemplate = Record->getDescribedClassTemplate();
  if (ClassTemplate)
    ClassTemplate = ClassTemplate->getCanonicalDecl();
  else if (ClassTemplatePartialSpecializationDecl *PartialSpec
             = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record))
    ClassTemplate = PartialSpec->getSpecializedTemplate()->getCanonicalDecl();

  // Walk the current context to find either the record or an instantiation of
  // it.
  DeclContext *DC = CurContext;
  while (!DC->isFileContext()) {
    // If we're performing substitution while we're inside the template
    // definition, we'll find our own context. We're done.
    if (DC->Equals(Record))
      return Record;

    if (CXXRecordDecl *InstRecord = dyn_cast<CXXRecordDecl>(DC)) {
      // Check whether we're in the process of instantiating a class template
      // specialization of the template we're mapping.
      if (ClassTemplateSpecializationDecl *InstSpec
                    = dyn_cast<ClassTemplateSpecializationDecl>(InstRecord)){
        ClassTemplateDecl *SpecTemplate = InstSpec->getSpecializedTemplate();
        if (ClassTemplate && isInstantiationOf(ClassTemplate, SpecTemplate))
          return InstRecord;
      }

      // Check whether we're in the process of instantiating a member class.
      if (isInstantiationOf(Record, InstRecord))
        return InstRecord;
    }

    // Move to the outer template scope.
    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(DC)) {
      if (FD->getFriendObjectKind() && FD->getDeclContext()->isFileContext()){
        DC = FD->getLexicalDeclContext();
        continue;
      }
      // An implicit deduction guide acts as if it's within the class template
      // specialization described by its name and first N template params.
      auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FD);
      if (Guide && Guide->isImplicit()) {
        TemplateDecl *TD = Guide->getDeducedTemplate();
        // Convert the arguments to an "as-written" list.
        TemplateArgumentListInfo Args(Loc, Loc);
        for (TemplateArgument Arg : TemplateArgs.getInnermost().take_front(
                                      TD->getTemplateParameters()->size())) {
          ArrayRef<TemplateArgument> Unpacked(Arg);
          if (Arg.getKind() == TemplateArgument::Pack)
            Unpacked = Arg.pack_elements();
          for (TemplateArgument UnpackedArg : Unpacked)
            Args.addArgument(
                getTrivialTemplateArgumentLoc(UnpackedArg, QualType(), Loc));
        }
        QualType T = CheckTemplateIdType(TemplateName(TD), Loc, Args);
        if (T.isNull())
          return nullptr;
        auto *SubstRecord = T->getAsCXXRecordDecl();
        assert(SubstRecord && "class template id not a class type?")((void)0);
        // Check that this template-id names the primary template and not a
        