SemaExprCXX.cpp

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//===--- SemaExprCXX.cpp - Semantic Analysis for Expressions --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Implements semantic analysis for C++ expressions.
///
//===----------------------------------------------------------------------===//
 
#include "clang/Sema/Template.h"
#include "clang/Sema/SemaInternal.h"
#include "TreeTransform.h"
#include "TypeLocBuilder.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/AlignedAllocation.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaLambda.h"
#include "clang/Sema/TemplateDeduction.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;
using namespace sema;
 
/// Handle the result of the special case name lookup for inheriting
/// constructor declarations. 'NS::X::X' and 'NS::X<...>::X' are treated as
/// constructor names in member using declarations, even if 'X' is not the
/// name of the corresponding type.
ParsedType Sema::getInheritingConstructorName(CXXScopeSpec &SS,
                                              SourceLocation NameLoc,
                                              IdentifierInfo &Name) {
  NestedNameSpecifier *NNS = SS.getScopeRep();
 
  // Convert the nested-name-specifier into a type.
  QualType Type;
  switch (NNS->getKind()) {
  case NestedNameSpecifier::TypeSpec:
  case NestedNameSpecifier::TypeSpecWithTemplate:
    Type = QualType(NNS->getAsType(), 0);
    break;
 
  case NestedNameSpecifier::Identifier:
    // Strip off the last layer of the nested-name-specifier and build a
    // typename type for it.
    assert(NNS->getAsIdentifier() == &Name && "not a constructor name");
    Type = Context.getDependentNameType(ETK_None, NNS->getPrefix(),
                                        NNS->getAsIdentifier());
    break;
 
  case NestedNameSpecifier::Global:
  case NestedNameSpecifier::Super:
  case NestedNameSpecifier::Namespace:
  case NestedNameSpecifier::NamespaceAlias:
    llvm_unreachable("Nested name specifier is not a type for inheriting ctor");
  }
 
  // This reference to the type is located entirely at the location of the
  // final identifier in the qualified-id.
  return CreateParsedType(Type,
                          Context.getTrivialTypeSourceInfo(Type, NameLoc));
}
 
ParsedType Sema::getConstructorName(IdentifierInfo &II,
                                    SourceLocation NameLoc,
                                    Scope *S, CXXScopeSpec &SS,
                                    bool EnteringContext) {
  CXXRecordDecl *CurClass = getCurrentClass(S, &SS);
  assert(CurClass && &II == CurClass->getIdentifier() &&
         "not a constructor name");
 
  // When naming a constructor as a member of a dependent context (eg, in a
  // friend declaration or an inherited constructor declaration), form an
  // unresolved "typename" type.
  if (CurClass->isDependentContext() && !EnteringContext && SS.getScopeRep()) {
    QualType T = Context.getDependentNameType(ETK_None, SS.getScopeRep(), &II);
    return ParsedType::make(T);
  }
 
  if (SS.isNotEmpty() && RequireCompleteDeclContext(SS, CurClass))
    return ParsedType();
 
  // Find the injected-class-name declaration. Note that we make no attempt to
  // diagnose cases where the injected-class-name is shadowed: the only
  // declaration that can validly shadow the injected-class-name is a
  // non-static data member, and if the class contains both a non-static data
  // member and a constructor then it is ill-formed (we check that in
  // CheckCompletedCXXClass).
  CXXRecordDecl *InjectedClassName = nullptr;
  for (NamedDecl *ND : CurClass->lookup(&II)) {
    auto *RD = dyn_cast<CXXRecordDecl>(ND);
    if (RD && RD->isInjectedClassName()) {
      InjectedClassName = RD;
      break;
    }
  }
  if (!InjectedClassName) {
    if (!CurClass->isInvalidDecl()) {
      // FIXME: RequireCompleteDeclContext doesn't check dependent contexts
      // properly. Work around it here for now.
      Diag(SS.getLastQualifierNameLoc(),
           diag::err_incomplete_nested_name_spec) << CurClass << SS.getRange();
    }
    return ParsedType();
  }
 
  QualType T = Context.getTypeDeclType(InjectedClassName);
  DiagnoseUseOfDecl(InjectedClassName, NameLoc);
  MarkAnyDeclReferenced(NameLoc, InjectedClassName, /*OdrUse=*/false);
 
  return ParsedType::make(T);
}
 
ParsedType Sema::getDestructorName(SourceLocation TildeLoc,
                                   IdentifierInfo &II,
                                   SourceLocation NameLoc,
                                   Scope *S, CXXScopeSpec &SS,
                                   ParsedType ObjectTypePtr,
                                   bool EnteringContext) {
  // Determine where to perform name lookup.
 
  // FIXME: This area of the standard is very messy, and the current
  // wording is rather unclear about which scopes we search for the
  // destructor name; see core issues 399 and 555. Issue 399 in
  // particular shows where the current description of destructor name
  // lookup is completely out of line with existing practice, e.g.,
  // this appears to be ill-formed:
  //
  //   namespace N {
  //     template <typename T> struct S {
  //       ~S();
  //     };
  //   }
  //
  //   void f(N::S<int>* s) {
  //     s->N::S<int>::~S();
  //   }
  //
  // See also PR6358 and PR6359.
  //
  // For now, we accept all the cases in which the name given could plausibly
  // be interpreted as a correct destructor name, issuing off-by-default
  // extension diagnostics on the cases that don't strictly conform to the
  // C++20 rules. This basically means we always consider looking in the
  // nested-name-specifier prefix, the complete nested-name-specifier, and
  // the scope, and accept if we find the expected type in any of the three
  // places.
 
  if (SS.isInvalid())
    return nullptr;
 
  // Whether we've failed with a diagnostic already.
  bool Failed = false;
 
  llvm::SmallVector<NamedDecl*, 8> FoundDecls;
  llvm::SmallPtrSet<CanonicalDeclPtr<Decl>, 8> FoundDeclSet;
 
  // If we have an object type, it's because we are in a
  // pseudo-destructor-expression or a member access expression, and
  // we know what type we're looking for.
  QualType SearchType =
      ObjectTypePtr ? GetTypeFromParser(ObjectTypePtr) : QualType();
 
  auto CheckLookupResult = [&](LookupResult &Found) -> ParsedType {
    auto IsAcceptableResult = [&](NamedDecl *D) -> bool {
      auto *Type = dyn_cast<TypeDecl>(D->getUnderlyingDecl());
      if (!Type)
        return false;
 
      if (SearchType.isNull() || SearchType->isDependentType())
        return true;
 
      QualType T = Context.getTypeDeclType(Type);
      return Context.hasSameUnqualifiedType(T, SearchType);
    };
 
    unsigned NumAcceptableResults = 0;
    for (NamedDecl *D : Found) {
      if (IsAcceptableResult(D))
        ++NumAcceptableResults;
 
      // Don't list a class twice in the lookup failure diagnostic if it's
      // found by both its injected-class-name and by the name in the enclosing
      // scope.
      if (auto *RD = dyn_cast<CXXRecordDecl>(D))
        if (RD->isInjectedClassName())
          D = cast<NamedDecl>(RD->getParent());
 
      if (FoundDeclSet.insert(D).second)
        FoundDecls.push_back(D);
    }
 
    // As an extension, attempt to "fix" an ambiguity by erasing all non-type
    // results, and all non-matching results if we have a search type. It's not
    // clear what the right behavior is if destructor lookup hits an ambiguity,
    // but other compilers do generally accept at least some kinds of
    // ambiguity.
    if (Found.isAmbiguous() && NumAcceptableResults == 1) {
      Diag(NameLoc, diag::ext_dtor_name_ambiguous);
      LookupResult::Filter F = Found.makeFilter();
      while (F.hasNext()) {
        NamedDecl *D = F.next();
        if (auto *TD = dyn_cast<TypeDecl>(D->getUnderlyingDecl()))
          Diag(D->getLocation(), diag::note_destructor_type_here)
              << Context.getTypeDeclType(TD);
        else
          Diag(D->getLocation(), diag::note_destructor_nontype_here);
 
        if (!IsAcceptableResult(D))
          F.erase();
      }
      F.done();
    }
 
    if (Found.isAmbiguous())
      Failed = true;
 
    if (TypeDecl *Type = Found.getAsSingle<TypeDecl>()) {
      if (IsAcceptableResult(Type)) {
        QualType T = Context.getTypeDeclType(Type);
        MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
        return CreateParsedType(T,
                                Context.getTrivialTypeSourceInfo(T, NameLoc));
      }
    }
 
    return nullptr;
  };
 
  bool IsDependent = false;
 
  auto LookupInObjectType = [&]() -> ParsedType {
    if (Failed || SearchType.isNull())
      return nullptr;
 
    IsDependent |= SearchType->isDependentType();
 
    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
    DeclContext *LookupCtx = computeDeclContext(SearchType);
    if (!LookupCtx)
      return nullptr;
    LookupQualifiedName(Found, LookupCtx);
    return CheckLookupResult(Found);
  };
 
  auto LookupInNestedNameSpec = [&](CXXScopeSpec &LookupSS) -> ParsedType {
    if (Failed)
      return nullptr;
 
    IsDependent |= isDependentScopeSpecifier(LookupSS);
    DeclContext *LookupCtx = computeDeclContext(LookupSS, EnteringContext);
    if (!LookupCtx)
      return nullptr;
 
    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
    if (RequireCompleteDeclContext(LookupSS, LookupCtx)) {
      Failed = true;
      return nullptr;
    }
    LookupQualifiedName(Found, LookupCtx);
    return CheckLookupResult(Found);
  };
 
  auto LookupInScope = [&]() -> ParsedType {
    if (Failed || !S)
      return nullptr;
 
    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
    LookupName(Found, S);
    return CheckLookupResult(Found);
  };
 
  // C++2a [basic.lookup.qual]p6:
  //   In a qualified-id of the form
  //
  //     nested-name-specifier[opt] type-name :: ~ type-name
  //
  //   the second type-name is looked up in the same scope as the first.
  //
  // We interpret this as meaning that if you do a dual-scope lookup for the
  // first name, you also do a dual-scope lookup for the second name, per
  // C++ [basic.lookup.classref]p4:
  //
  //   If the id-expression in a class member access is a qualified-id of the
  //   form
  //
  //     class-name-or-namespace-name :: ...
  //
  //   the class-name-or-namespace-name following the . or -> is first looked
  //   up in the class of the object expression and the name, if found, is used.
  //   Otherwise, it is looked up in the context of the entire
  //   postfix-expression.
  //
  // This looks in the same scopes as for an unqualified destructor name:
  //
  // C++ [basic.lookup.classref]p3:
  //   If the unqualified-id is ~ type-name, the type-name is looked up
  //   in the context of the entire postfix-expression. If the type T
  //   of the object expression is of a class type C, the type-name is
  //   also looked up in the scope of class C. At least one of the
  //   lookups shall find a name that refers to cv T.
  //
  // FIXME: The intent is unclear here. Should type-name::~type-name look in
  // the scope anyway if it finds a non-matching name declared in the class?
  // If both lookups succeed and find a dependent result, which result should
  // we retain? (Same question for p->~type-name().)
 
  if (NestedNameSpecifier *Prefix =
      SS.isSet() ? SS.getScopeRep()->getPrefix() : nullptr) {
    // This is
    //
    //   nested-name-specifier type-name :: ~ type-name
    //
    // Look for the second type-name in the nested-name-specifier.
    CXXScopeSpec PrefixSS;
    PrefixSS.Adopt(NestedNameSpecifierLoc(Prefix, SS.location_data()));
    if (ParsedType T = LookupInNestedNameSpec(PrefixSS))
      return T;
  } else {
    // This is one of
    //
    //   type-name :: ~ type-name
    //   ~ type-name
    //
    // Look in the scope and (if any) the object type.
    if (ParsedType T = LookupInScope())
      return T;
    if (ParsedType T = LookupInObjectType())
      return T;
  }
 
  if (Failed)
    return nullptr;
 
  if (IsDependent) {
    // We didn't find our type, but that's OK: it's dependent anyway.
 
    // FIXME: What if we have no nested-name-specifier?
    QualType T = CheckTypenameType(ETK_None, SourceLocation(),
                                   SS.getWithLocInContext(Context),
                                   II, NameLoc);
    return ParsedType::make(T);
  }
 
  // The remaining cases are all non-standard extensions imitating the behavior
  // of various other compilers.
  unsigned NumNonExtensionDecls = FoundDecls.size();
 
  if (SS.isSet()) {
    // For compatibility with older broken C++ rules and existing code,
    //
    //   nested-name-specifier :: ~ type-name
    //
    // also looks for type-name within the nested-name-specifier.
    if (ParsedType T = LookupInNestedNameSpec(SS)) {
      Diag(SS.getEndLoc(), diag::ext_dtor_named_in_wrong_scope)
          << SS.getRange()
          << FixItHint::CreateInsertion(SS.getEndLoc(),
                                        ("::" + II.getName()).str());
      return T;
    }
 
    // For compatibility with other compilers and older versions of Clang,
    //
    //   nested-name-specifier type-name :: ~ type-name
    //
    // also looks for type-name in the scope. Unfortunately, we can't
    // reasonably apply this fallback for dependent nested-name-specifiers.
    if (SS.getScopeRep()->getPrefix()) {
      if (ParsedType T = LookupInScope()) {
        Diag(SS.getEndLoc(), diag::ext_qualified_dtor_named_in_lexical_scope)
            << FixItHint::CreateRemoval(SS.getRange());
        Diag(FoundDecls.back()->getLocation(), diag::note_destructor_type_here)
            << GetTypeFromParser(T);
        return T;
      }
    }
  }
 
  // We didn't find anything matching; tell the user what we did find (if
  // anything).
 
  // Don't tell the user about declarations we shouldn't have found.
  FoundDecls.resize(NumNonExtensionDecls);
 
  // List types before non-types.
  std::stable_sort(FoundDecls.begin(), FoundDecls.end(),
                   [](NamedDecl *A, NamedDecl *B) {
                     return isa<TypeDecl>(A->getUnderlyingDecl()) >
                            isa<TypeDecl>(B->getUnderlyingDecl());
                   });
 
  // Suggest a fixit to properly name the destroyed type.
  auto MakeFixItHint = [&]{
    const CXXRecordDecl *Destroyed = nullptr;
    // FIXME: If we have a scope specifier, suggest its last component?
    if (!SearchType.isNull())
      Destroyed = SearchType->getAsCXXRecordDecl();
    else if (S)
      Destroyed = dyn_cast_or_null<CXXRecordDecl>(S->getEntity());
    if (Destroyed)
      return FixItHint::CreateReplacement(SourceRange(NameLoc),
                                          Destroyed->getNameAsString());
    return FixItHint();
  };
 
  if (FoundDecls.empty()) {
    // FIXME: Attempt typo-correction?
    Diag(NameLoc, diag::err_undeclared_destructor_name)
      << &II << MakeFixItHint();
  } else if (!SearchType.isNull() && FoundDecls.size() == 1) {
    if (auto *TD = dyn_cast<TypeDecl>(FoundDecls[0]->getUnderlyingDecl())) {
      assert(!SearchType.isNull() &&
             "should only reject a type result if we have a search type");
      QualType T = Context.getTypeDeclType(TD);
      Diag(NameLoc, diag::err_destructor_expr_type_mismatch)
          << T << SearchType << MakeFixItHint();
    } else {
      Diag(NameLoc, diag::err_destructor_expr_nontype)
          << &II << MakeFixItHint();
    }
  } else {
    Diag(NameLoc, SearchType.isNull() ? diag::err_destructor_name_nontype
                                      : diag::err_destructor_expr_mismatch)
        << &II << SearchType << MakeFixItHint();
  }
 
  for (NamedDecl *FoundD : FoundDecls) {
    if (auto *TD = dyn_cast<TypeDecl>(FoundD->getUnderlyingDecl()))
      Diag(FoundD->getLocation(), diag::note_destructor_type_here)
          << Context.getTypeDeclType(TD);
    else
      Diag(FoundD->getLocation(), diag::note_destructor_nontype_here)
          << FoundD;
  }
 
  return nullptr;
}
 
ParsedType Sema::getDestructorTypeForDecltype(const DeclSpec &DS,
                                              ParsedType ObjectType) {
  if (DS.getTypeSpecType() == DeclSpec::TST_error)
    return nullptr;
 
  if (DS.getTypeSpecType() == DeclSpec::TST_decltype_auto) {
    Diag(DS.getTypeSpecTypeLoc(), diag::err_decltype_auto_invalid);
    return nullptr;
  }
 
  assert(DS.getTypeSpecType() == DeclSpec::TST_decltype &&
         "unexpected type in getDestructorType");
  QualType T = BuildDecltypeType(DS.getRepAsExpr());
 
  // If we know the type of the object, check that the correct destructor
  // type was named now; we can give better diagnostics this way.
  QualType SearchType = GetTypeFromParser(ObjectType);
  if (!SearchType.isNull() && !SearchType->isDependentType() &&
      !Context.hasSameUnqualifiedType(T, SearchType)) {
    Diag(DS.getTypeSpecTypeLoc(), diag::err_destructor_expr_type_mismatch)
      << T << SearchType;
    return nullptr;
  }
 
  return ParsedType::make(T);
}
 
bool Sema::checkLiteralOperatorId(const CXXScopeSpec &SS,
                                  const UnqualifiedId &Name, bool IsUDSuffix) {
  assert(Name.getKind() == UnqualifiedIdKind::IK_LiteralOperatorId);
  if (!IsUDSuffix) {
    // [over.literal] p8
    //
    // double operator""_Bq(long double);  // OK: not a reserved identifier
    // double operator"" _Bq(long double); // ill-formed, no diagnostic required
    IdentifierInfo *II = Name.Identifier;
    ReservedIdentifierStatus Status = II->isReserved(PP.getLangOpts());
    SourceLocation Loc = Name.getEndLoc();
    if (isReservedInAllContexts(Status) &&
        !PP.getSourceManager().isInSystemHeader(Loc)) {
      Diag(Loc, diag::warn_reserved_extern_symbol)
          << II << static_cast<int>(Status)
          << FixItHint::CreateReplacement(
                 Name.getSourceRange(),
                 (StringRef("operator\"\"") + II->getName()).str());
    }
  }
 
  if (!SS.isValid())
    return false;
 
  switch (SS.getScopeRep()->getKind()) {
  case NestedNameSpecifier::Identifier:
  case NestedNameSpecifier::TypeSpec:
  case NestedNameSpecifier::TypeSpecWithTemplate:
    // Per C++11 [over.literal]p2, literal operators can only be declared at
    // namespace scope. Therefore, this unqualified-id cannot name anything.
    // Reject it early, because we have no AST representation for this in the
    // case where the scope is dependent.
    Diag(Name.getBeginLoc(), diag::err_literal_operator_id_outside_namespace)
        << SS.getScopeRep();
    return true;
 
  case NestedNameSpecifier::Global:
  case NestedNameSpecifier::Super:
  case NestedNameSpecifier::Namespace:
  case NestedNameSpecifier::NamespaceAlias:
    return false;
  }
 
  llvm_unreachable("unknown nested name specifier kind");
}
 
/// Build a C++ typeid expression with a type operand.
ExprResult Sema::BuildCXXTypeId(QualType TypeInfoType,
                                SourceLocation TypeidLoc,
                                TypeSourceInfo *Operand,
                                SourceLocation RParenLoc) {
  // C++ [expr.typeid]p4:
  //   The top-level cv-qualifiers of the lvalue expression or the type-id
  //   that is the operand of typeid are always ignored.
  //   If the type of the type-id is a class type or a reference to a class
  //   type, the class shall be completely-defined.
  Qualifiers Quals;
  QualType T
    = Context.getUnqualifiedArrayType(Operand->getType().getNonReferenceType(),
                                      Quals);
  if (T->getAs<RecordType>() &&
      RequireCompleteType(TypeidLoc, T, diag::err_incomplete_typeid))
    return ExprError();
 
  if (T->isVariablyModifiedType())
    return ExprError(Diag(TypeidLoc, diag::err_variably_modified_typeid) << T);
 
  if (CheckQualifiedFunctionForTypeId(T, TypeidLoc))
    return ExprError();
 
  return new (Context) CXXTypeidExpr(TypeInfoType.withConst(), Operand,
                                     SourceRange(TypeidLoc, RParenLoc));
}
 
/// Build a C++ typeid expression with an expression operand.
ExprResult Sema::BuildCXXTypeId(QualType TypeInfoType,
                                SourceLocation TypeidLoc,
                                Expr *E,
                                SourceLocation RParenLoc) {
  bool WasEvaluated = false;
  if (E && !E->isTypeDependent()) {
    if (E->getType()->isPlaceholderType()) {
      ExprResult result = CheckPlaceholderExpr(E);
      if (result.isInvalid()) return ExprError();
      E = result.get();
    }
 
    QualType T = E->getType();
    if (const RecordType *RecordT = T->getAs<RecordType>()) {
      CXXRecordDecl *RecordD = cast<CXXRecordDecl>(RecordT->getDecl());
      // C++ [expr.typeid]p3:
      //   [...] If the type of the expression is a class type, the class
      //   shall be completely-defined.
      if (RequireCompleteType(TypeidLoc, T, diag::err_incomplete_typeid))
        return ExprError();
 
      // C++ [expr.typeid]p3:
      //   When typeid is applied to an expression other than an glvalue of a
      //   polymorphic class type [...] [the] expression is an unevaluated
      //   operand. [...]
      if (RecordD->isPolymorphic() && E->isGLValue()) {
        if (isUnevaluatedContext()) {
          // The operand was processed in unevaluated context, switch the
          // context and recheck the subexpression.
          ExprResult Result = TransformToPotentiallyEvaluated(E);
          if (Result.isInvalid())
            return ExprError();
          E = Result.get();
        }
 
        // We require a vtable to query the type at run time.
        MarkVTableUsed(TypeidLoc, RecordD);
        WasEvaluated = true;
      }
    }
 
    ExprResult Result = CheckUnevaluatedOperand(E);
    if (Result.isInvalid())
      return ExprError();
    E = Result.get();
 
    // C++ [expr.typeid]p4:
    //   [...] If the type of the type-id is a reference to a possibly
    //   cv-qualified type, the result of the typeid expression refers to a
    //   std::type_info object representing the cv-unqualified referenced
    //   type.
    Qualifiers Quals;
    QualType UnqualT = Context.getUnqualifiedArrayType(T, Quals);
    if (!Context.hasSameType(T, UnqualT)) {
      T = UnqualT;
      E = ImpCastExprToType(E, UnqualT, CK_NoOp, E->getValueKind()).get();
    }
  }
 
  if (E->getType()->isVariablyModifiedType())
    return ExprError(Diag(TypeidLoc, diag::err_variably_modified_typeid)
                     << E->getType());
  else if (!inTemplateInstantiation() &&
           E->HasSideEffects(Context, WasEvaluated)) {
    // The expression operand for typeid is in an unevaluated expression
    // context, so side effects could result in unintended consequences.
    Diag(E->getExprLoc(), WasEvaluated
                              ? diag::warn_side_effects_typeid
                              : diag::warn_side_effects_unevaluated_context);
  }
 
  return new (Context) CXXTypeidExpr(TypeInfoType.withConst(), E,
                                     SourceRange(TypeidLoc, RParenLoc));
}
 
/// ActOnCXXTypeidOfType - Parse typeid( type-id ) or typeid (expression);
ExprResult
Sema::ActOnCXXTypeid(SourceLocation OpLoc, SourceLocation LParenLoc,
                     bool isType, void *TyOrExpr, SourceLocation RParenLoc) {
  // typeid is not supported in OpenCL.
  if (getLangOpts().OpenCLCPlusPlus) {
    return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported)
                     << "typeid");
  }
 
  // Find the std::type_info type.
  if (!getStdNamespace())
    return ExprError(Diag(OpLoc, diag::err_need_header_before_typeid));
 
  if (!CXXTypeInfoDecl) {
    IdentifierInfo *TypeInfoII = &PP.getIdentifierTable().get("type_info");
    LookupResult R(*this, TypeInfoII, SourceLocation(), LookupTagName);
    LookupQualifiedName(R, getStdNamespace());
    CXXTypeInfoDecl = R.getAsSingle<RecordDecl>();
    // Microsoft's typeinfo doesn't have type_info in std but in the global
    // namespace if _HAS_EXCEPTIONS is defined to 0. See PR13153.
    if (!CXXTypeInfoDecl && LangOpts.MSVCCompat) {
      LookupQualifiedName(R, Context.getTranslationUnitDecl());
      CXXTypeInfoDecl = R.getAsSingle<RecordDecl>();
    }
    if (!CXXTypeInfoDecl)
      return ExprError(Diag(OpLoc, diag::err_need_header_before_typeid));
  }
 
  if (!getLangOpts().RTTI) {
    return ExprError(Diag(OpLoc, diag::err_no_typeid_with_fno_rtti));
  }
 
  QualType TypeInfoType = Context.getTypeDeclType(CXXTypeInfoDecl);
 
  if (isType) {
    // The operand is a type; handle it as such.
    TypeSourceInfo *TInfo = nullptr;
    QualType T = GetTypeFromParser(ParsedType::getFromOpaquePtr(TyOrExpr),
                                   &TInfo);
    if (T.isNull())
      return ExprError();
 
    if (!TInfo)
      TInfo = Context.getTrivialTypeSourceInfo(T, OpLoc);
 
    return BuildCXXTypeId(TypeInfoType, OpLoc, TInfo, RParenLoc);
  }
 
  // The operand is an expression.
  ExprResult Result =
      BuildCXXTypeId(TypeInfoType, OpLoc, (Expr *)TyOrExpr, RParenLoc);
 
  if (!getLangOpts().RTTIData && !Result.isInvalid())
    if (auto *CTE = dyn_cast<CXXTypeidExpr>(Result.get()))
      if (CTE->isPotentiallyEvaluated() && !CTE->isMostDerived(Context))
        Diag(OpLoc, diag::warn_no_typeid_with_rtti_disabled)
            << (getDiagnostics().getDiagnosticOptions().getFormat() ==
                DiagnosticOptions::MSVC);
  return Result;
}
 
/// Grabs __declspec(uuid()) off a type, or returns 0 if we cannot resolve to
/// a single GUID.
static void
getUuidAttrOfType(Sema &SemaRef, QualType QT,
                  llvm::SmallSetVector<const UuidAttr *, 1> &UuidAttrs) {
  // Optionally remove one level of pointer, reference or array indirection.
  const Type *Ty = QT.getTypePtr();
  if (QT->isPointerType() || QT->isReferenceType())
    Ty = QT->getPointeeType().getTypePtr();
  else if (QT->isArrayType())
    Ty = Ty->getBaseElementTypeUnsafe();
 
  const auto *TD = Ty->getAsTagDecl();
  if (!TD)
    return;
 
  if (const auto *Uuid = TD->getMostRecentDecl()->getAttr<UuidAttr>()) {
    UuidAttrs.insert(Uuid);
    return;
  }
 
  // __uuidof can grab UUIDs from template arguments.
  if (const auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(TD)) {
    const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
    for (const TemplateArgument &TA : TAL.asArray()) {
      const UuidAttr *UuidForTA = nullptr;
      if (TA.getKind() == TemplateArgument::Type)
        getUuidAttrOfType(SemaRef, TA.getAsType(), UuidAttrs);
      else if (TA.getKind() == TemplateArgument::Declaration)
        getUuidAttrOfType(SemaRef, TA.getAsDecl()->getType(), UuidAttrs);
 
      if (UuidForTA)
        UuidAttrs.insert(UuidForTA);
    }
  }
}
 
/// Build a Microsoft __uuidof expression with a type operand.
ExprResult Sema::BuildCXXUuidof(QualType Type,
                                SourceLocation TypeidLoc,
                                TypeSourceInfo *Operand,
                                SourceLocation RParenLoc) {
  MSGuidDecl *Guid = nullptr;
  if (!Operand->getType()->isDependentType()) {
    llvm::SmallSetVector<const UuidAttr *, 1> UuidAttrs;
    getUuidAttrOfType(*this, Operand->getType(), UuidAttrs);
    if (UuidAttrs.empty())
      return ExprError(Diag(TypeidLoc, diag::err_uuidof_without_guid));
    if (UuidAttrs.size() > 1)
      return ExprError(Diag(TypeidLoc, diag::err_uuidof_with_multiple_guids));
    Guid = UuidAttrs.back()->getGuidDecl();
  }
 
  return new (Context)
      CXXUuidofExpr(Type, Operand, Guid, SourceRange(TypeidLoc, RParenLoc));
}
 
/// Build a Microsoft __uuidof expression with an expression operand.
ExprResult Sema::BuildCXXUuidof(QualType Type, SourceLocation TypeidLoc,
                                Expr *E, SourceLocation RParenLoc) {
  MSGuidDecl *Guid = nullptr;
  if (!E->getType()->isDependentType()) {
    if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull)) {
      // A null pointer results in {00000000-0000-0000-0000-000000000000}.
      Guid = Context.getMSGuidDecl(MSGuidDecl::Parts{});
    } else {
      llvm::SmallSetVector<const UuidAttr *, 1> UuidAttrs;
      getUuidAttrOfType(*this, E->getType(), UuidAttrs);
      if (UuidAttrs.empty())
        return ExprError(Diag(TypeidLoc, diag::err_uuidof_without_guid));
      if (UuidAttrs.size() > 1)
        return ExprError(Diag(TypeidLoc, diag::err_uuidof_with_multiple_guids));
      Guid = UuidAttrs.back()->getGuidDecl();
    }
  }
 
  return new (Context)
      CXXUuidofExpr(Type, E, Guid, SourceRange(TypeidLoc, RParenLoc));
}
 
/// ActOnCXXUuidof - Parse __uuidof( type-id ) or __uuidof (expression);
ExprResult
Sema::ActOnCXXUuidof(SourceLocation OpLoc, SourceLocation LParenLoc,
                     bool isType, void *TyOrExpr, SourceLocation RParenLoc) {
  QualType GuidType = Context.getMSGuidType();
  GuidType.addConst();
 
  if (isType) {
    // The operand is a type; handle it as such.
    TypeSourceInfo *TInfo = nullptr;
    QualType T = GetTypeFromParser(ParsedType::getFromOpaquePtr(TyOrExpr),
                                   &TInfo);
    if (T.isNull())
      return ExprError();
 
    if (!TInfo)
      TInfo = Context.getTrivialTypeSourceInfo(T, OpLoc);
 
    return BuildCXXUuidof(GuidType, OpLoc, TInfo, RParenLoc);
  }
 
  // The operand is an expression.
  return BuildCXXUuidof(GuidType, OpLoc, (Expr*)TyOrExpr, RParenLoc);
}
 
/// ActOnCXXBoolLiteral - Parse {true,false} literals.
ExprResult
Sema::ActOnCXXBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind) {
  assert((Kind == tok::kw_true || Kind == tok::kw_false) &&
         "Unknown C++ Boolean value!");
  return new (Context)
      CXXBoolLiteralExpr(Kind == tok::kw_true, Context.BoolTy, OpLoc);
}
 
/// ActOnCXXNullPtrLiteral - Parse 'nullptr'.
ExprResult
Sema::ActOnCXXNullPtrLiteral(SourceLocation Loc) {
  return new (Context) CXXNullPtrLiteralExpr(Context.NullPtrTy, Loc);
}
 
/// ActOnCXXThrow - Parse throw expressions.
ExprResult
Sema::ActOnCXXThrow(Scope *S, SourceLocation OpLoc, Expr *Ex) {
  bool IsThrownVarInScope = false;
  if (Ex) {
    // C++0x [class.copymove]p31:
    //   When certain criteria are met, an implementation is allowed to omit the
    //   copy/move construction of a class object [...]
    //
    //     - in a throw-expression, when the operand is the name of a
    //       non-volatile automatic object (other than a function or catch-
    //       clause parameter) whose scope does not extend beyond the end of the
    //       innermost enclosing try-block (if there is one), the copy/move
    //       operation from the operand to the exception object (15.1) can be
    //       omitted by constructing the automatic object directly into the
    //       exception object
    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Ex->IgnoreParens()))
      if (VarDecl *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
        if (Var->hasLocalStorage() && !Var->getType().isVolatileQualified()) {
          for( ; S; S = S->getParent()) {
            if (S->isDeclScope(Var)) {
              IsThrownVarInScope = true;
              break;
            }
 
            if (S->getFlags() &
                (Scope::FnScope | Scope::ClassScope | Scope::BlockScope |
                 Scope::FunctionPrototypeScope | Scope::ObjCMethodScope |
                 Scope::TryScope))
              break;
          }
        }
      }
  }
 
  return BuildCXXThrow(OpLoc, Ex, IsThrownVarInScope);
}
 
ExprResult Sema::BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
                               bool IsThrownVarInScope) {
  // Don't report an error if 'throw' is used in system headers.
  if (!getLangOpts().CXXExceptions &&
      !getSourceManager().isInSystemHeader(OpLoc) && !getLangOpts().CUDA) {
    // Delay error emission for the OpenMP device code.
    targetDiag(OpLoc, diag::err_exceptions_disabled) << "throw";
  }
 
  // Exceptions aren't allowed in CUDA device code.
  if (getLangOpts().CUDA)
    CUDADiagIfDeviceCode(OpLoc, diag::err_cuda_device_exceptions)
        << "throw" << CurrentCUDATarget();
 
  if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope())
    Diag(OpLoc, diag::err_omp_simd_region_cannot_use_stmt) << "throw";
 
  if (Ex && !Ex->isTypeDependent()) {
    // Initialize the exception result.  This implicitly weeds out
    // abstract types or types with inaccessible copy constructors.
 
    // C++0x [class.copymove]p31:
    //   When certain criteria are met, an implementation is allowed to omit the
    //   copy/move construction of a class object [...]
    //
    //     - in a throw-expression, when the operand is the name of a
    //       non-volatile automatic object (other than a function or
    //       catch-clause
    //       parameter) whose scope does not extend beyond the end of the
    //       innermost enclosing try-block (if there is one), the copy/move
    //       operation from the operand to the exception object (15.1) can be
    //       omitted by constructing the automatic object directly into the
    //       exception object
    NamedReturnInfo NRInfo =
        IsThrownVarInScope ? getNamedReturnInfo(Ex) : NamedReturnInfo();
 
    QualType ExceptionObjectTy = Context.getExceptionObjectType(Ex->getType());
    if (CheckCXXThrowOperand(OpLoc, ExceptionObjectTy, Ex))
      return ExprError();
 
    InitializedEntity Entity =
        InitializedEntity::InitializeException(OpLoc, ExceptionObjectTy);
    ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRInfo, Ex);
    if (Res.isInvalid())
      return ExprError();
    Ex = Res.get();
  }
 
  // PPC MMA non-pointer types are not allowed as throw expr types.
  if (Ex && Context.getTargetInfo().getTriple().isPPC64())
    CheckPPCMMAType(Ex->getType(), Ex->getBeginLoc());
 
  return new (Context)
      CXXThrowExpr(Ex, Context.VoidTy, OpLoc, IsThrownVarInScope);
}
 
static void
collectPublicBases(CXXRecordDecl *RD,
                   llvm::DenseMap<CXXRecordDecl *, unsigned> &SubobjectsSeen,
                   llvm::SmallPtrSetImpl<CXXRecordDecl *> &VBases,
                   llvm::SetVector<CXXRecordDecl *> &PublicSubobjectsSeen,
                   bool ParentIsPublic) {
  for (const CXXBaseSpecifier &BS : RD->bases()) {
    CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
    bool NewSubobject;
    // Virtual bases constitute the same subobject.  Non-virtual bases are
    // always distinct subobjects.
    if (BS.isVirtual())
      NewSubobject = VBases.insert(BaseDecl).second;
    else
      NewSubobject = true;
 
    if (NewSubobject)
      ++SubobjectsSeen[BaseDecl];
 
    // Only add subobjects which have public access throughout the entire chain.
    bool PublicPath = ParentIsPublic && BS.getAccessSpecifier() == AS_public;
    if (PublicPath)
      PublicSubobjectsSeen.insert(BaseDecl);
 
    // Recurse on to each base subobject.
    collectPublicBases(BaseDecl, SubobjectsSeen, VBases, PublicSubobjectsSeen,
                       PublicPath);
  }
}
 
static void getUnambiguousPublicSubobjects(
    CXXRecordDecl *RD, llvm::SmallVectorImpl<CXXRecordDecl *> &Objects) {
  llvm::DenseMap<CXXRecordDecl *, unsigned> SubobjectsSeen;
  llvm::SmallSet<CXXRecordDecl *, 2> VBases;
  llvm::SetVector<CXXRecordDecl *> PublicSubobjectsSeen;
  SubobjectsSeen[RD] = 1;
  PublicSubobjectsSeen.insert(RD);
  collectPublicBases(RD, SubobjectsSeen, VBases, PublicSubobjectsSeen,
                     /*ParentIsPublic=*/true);
 
  for (CXXRecordDecl *PublicSubobject : PublicSubobjectsSeen) {
    // Skip ambiguous objects.
    if (SubobjectsSeen[PublicSubobject] > 1)
      continue;
 
    Objects.push_back(PublicSubobject);
  }
}
 
/// CheckCXXThrowOperand - Validate the operand of a throw.
bool Sema::CheckCXXThrowOperand(SourceLocation ThrowLoc,
                                QualType ExceptionObjectTy, Expr *E) {
  //   If the type of the exception would be an incomplete type or a pointer
  //   to an incomplete type other than (cv) void the program is ill-formed.
  QualType Ty = ExceptionObjectTy;
  bool isPointer = false;
  if (const PointerType* Ptr = Ty->getAs<PointerType>()) {
    Ty = Ptr->getPointeeType();
    isPointer = true;
  }
  if (!isPointer || !Ty->isVoidType()) {
    if (RequireCompleteType(ThrowLoc, Ty,
                            isPointer ? diag::err_throw_incomplete_ptr
                                      : diag::err_throw_incomplete,
                            E->getSourceRange()))
      return true;
 
    if (!isPointer && Ty->isSizelessType()) {
      Diag(ThrowLoc, diag::err_throw_sizeless) << Ty << E->getSourceRange();
      return true;
    }
 
    if (RequireNonAbstractType(ThrowLoc, ExceptionObjectTy,
                               diag::err_throw_abstract_type, E))
      return true;
  }
 
  // If the exception has class type, we need additional handling.
  CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
  if (!RD)
    return false;
 
  // If we are throwing a polymorphic class type or pointer thereof,
  // exception handling will make use of the vtable.
  MarkVTableUsed(ThrowLoc, RD);
 
  // If a pointer is thrown, the referenced object will not be destroyed.
  if (isPointer)
    return false;
 
  // If the class has a destructor, we must be able to call it.
  if (!RD->hasIrrelevantDestructor()) {
    if (CXXDestructorDecl *Destructor = LookupDestructor(RD)) {
      MarkFunctionReferenced(E->getExprLoc(), Destructor);
      CheckDestructorAccess(E->getExprLoc(), Destructor,
                            PDiag(diag::err_access_dtor_exception) << Ty);
      if (DiagnoseUseOfDecl(Destructor, E->getExprLoc()))
        return true;
    }
  }
 
  // The MSVC ABI creates a list of all types which can catch the exception
  // object.  This list also references the appropriate copy constructor to call
  // if the object is caught by value and has a non-trivial copy constructor.
  if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
    // We are only interested in the public, unambiguous bases contained within
    // the exception object.  Bases which are ambiguous or otherwise
    // inaccessible are not catchable types.
    llvm::SmallVector<CXXRecordDecl *, 2> UnambiguousPublicSubobjects;
    getUnambiguousPublicSubobjects(RD, UnambiguousPublicSubobjects);
 
    for (CXXRecordDecl *Subobject : UnambiguousPublicSubobjects) {
      // Attempt to lookup the copy constructor.  Various pieces of machinery
      // will spring into action, like template instantiation, which means this
      // cannot be a simple walk of the class's decls.  Instead, we must perform
      // lookup and overload resolution.
      CXXConstructorDecl *CD = LookupCopyingConstructor(Subobject, 0);
      if (!CD || CD->isDeleted())
        continue;
 
      // Mark the constructor referenced as it is used by this throw expression.
      MarkFunctionReferenced(E->getExprLoc(), CD);
 
      // Skip this copy constructor if it is trivial, we don't need to record it
      // in the catchable type data.
      if (CD->isTrivial())
        continue;
 
      // The copy constructor is non-trivial, create a mapping from this class
      // type to this constructor.
      // N.B.  The selection of copy constructor is not sensitive to this
      // particular throw-site.  Lookup will be performed at the catch-site to
      // ensure that the copy constructor is, in fact, accessible (via
      // friendship or any other means).
      Context.addCopyConstructorForExceptionObject(Subobject, CD);
 
      // We don't keep the instantiated default argument expressions around so
      // we must rebuild them here.
      for (unsigned I = 1, E = CD->getNumParams(); I != E; ++I) {
        if (CheckCXXDefaultArgExpr(ThrowLoc, CD, CD->getParamDecl(I)))
          return true;
      }
    }
  }
 
  // Under the Itanium C++ ABI, memory for the exception object is allocated by
  // the runtime with no ability for the compiler to request additional
  // alignment. Warn if the exception type requires alignment beyond the minimum
  // guaranteed by the target C++ runtime.
  if (Context.getTargetInfo().getCXXABI().isItaniumFamily()) {
    CharUnits TypeAlign = Context.getTypeAlignInChars(Ty);
    CharUnits ExnObjAlign = Context.getExnObjectAlignment();
    if (ExnObjAlign < TypeAlign) {
      Diag(ThrowLoc, diag::warn_throw_underaligned_obj);
      Diag(ThrowLoc, diag::note_throw_underaligned_obj)
          << Ty << (unsigned)TypeAlign.getQuantity()
          << (unsigned)ExnObjAlign.getQuantity();
    }
  }
 
  return false;
}
 
static QualType adjustCVQualifiersForCXXThisWithinLambda(
    ArrayRef<FunctionScopeInfo *> FunctionScopes, QualType ThisTy,
    DeclContext *CurSemaContext, ASTContext &ASTCtx) {
 
  QualType ClassType = ThisTy->getPointeeType();
  LambdaScopeInfo *CurLSI = nullptr;
  DeclContext *CurDC = CurSemaContext;
 
  // Iterate through the stack of lambdas starting from the innermost lambda to
  // the outermost lambda, checking if '*this' is ever captured by copy - since
  // that could change the cv-qualifiers of the '*this' object.
  // The object referred to by '*this' starts out with the cv-qualifiers of its
  // member function.  We then start with the innermost lambda and iterate
  // outward checking to see if any lambda performs a by-copy capture of '*this'
  // - and if so, any nested lambda must respect the 'constness' of that
  // capturing lamdbda's call operator.
  //
 
  // Since the FunctionScopeInfo stack is representative of the lexical
  // nesting of the lambda expressions during initial parsing (and is the best
  // place for querying information about captures about lambdas that are
  // partially processed) and perhaps during instantiation of function templates
  // that contain lambda expressions that need to be transformed BUT not
  // necessarily during instantiation of a nested generic lambda's function call
  // operator (which might even be instantiated at the end of the TU) - at which
  // time the DeclContext tree is mature enough to query capture information
  // reliably - we use a two pronged approach to walk through all the lexically
  // enclosing lambda expressions:
  //
  //  1) Climb down the FunctionScopeInfo stack as long as each item represents
  //  a Lambda (i.e. LambdaScopeInfo) AND each LSI's 'closure-type' is lexically
  //  enclosed by the call-operator of the LSI below it on the stack (while
  //  tracking the enclosing DC for step 2 if needed).  Note the topmost LSI on
  //  the stack represents the innermost lambda.
  //
  //  2) If we run out of enclosing LSI's, check if the enclosing DeclContext
  //  represents a lambda's call operator.  If it does, we must be instantiating
  //  a generic lambda's call operator (represented by the Current LSI, and
  //  should be the only scenario where an inconsistency between the LSI and the
  //  DeclContext should occur), so climb out the DeclContexts if they
  //  represent lambdas, while querying the corresponding closure types
  //  regarding capture information.
 
  // 1) Climb down the function scope info stack.
  for (int I = FunctionScopes.size();
       I-- && isa<LambdaScopeInfo>(FunctionScopes[I]) &&
       (!CurLSI || !CurLSI->Lambda || CurLSI->Lambda->getDeclContext() ==
                       cast<LambdaScopeInfo>(FunctionScopes[I])->CallOperator);
       CurDC = getLambdaAwareParentOfDeclContext(CurDC)) {
    CurLSI = cast<LambdaScopeInfo>(FunctionScopes[I]);
 
    if (!CurLSI->isCXXThisCaptured())
        continue;
 
    auto C = CurLSI->getCXXThisCapture();
 
    if (C.isCopyCapture()) {
      ClassType.removeLocalCVRQualifiers(Qualifiers::CVRMask);
      if (CurLSI->CallOperator->isConst())
        ClassType.addConst();
      return ASTCtx.getPointerType(ClassType);
    }
  }
 
  // 2) We've run out of ScopeInfos but check 1. if CurDC is a lambda (which
  //    can happen during instantiation of its nested generic lambda call
  //    operator); 2. if we're in a lambda scope (lambda body).
  if (CurLSI && isLambdaCallOperator(CurDC)) {
    assert(isGenericLambdaCallOperatorSpecialization(CurLSI->CallOperator) &&
           "While computing 'this' capture-type for a generic lambda, when we "
           "run out of enclosing LSI's, yet the enclosing DC is a "
           "lambda-call-operator we must be (i.e. Current LSI) in a generic "
           "lambda call oeprator");
    assert(CurDC == getLambdaAwareParentOfDeclContext(CurLSI->CallOperator));
 
    auto IsThisCaptured =
        [](CXXRecordDecl *Closure, bool &IsByCopy, bool &IsConst) {
      IsConst = false;
      IsByCopy = false;
      for (auto &&C : Closure->captures()) {
        if (C.capturesThis()) {
          if (C.getCaptureKind() == LCK_StarThis)
            IsByCopy = true;
          if (Closure->getLambdaCallOperator()->isConst())
            IsConst = true;
          return true;
        }
      }
      return false;
    };
 
    bool IsByCopyCapture = false;
    bool IsConstCapture = false;
    CXXRecordDecl *Closure = cast<CXXRecordDecl>(CurDC->getParent());
    while (Closure &&
           IsThisCaptured(Closure, IsByCopyCapture, IsConstCapture)) {
      if (IsByCopyCapture) {
        ClassType.removeLocalCVRQualifiers(Qualifiers::CVRMask);
        if (IsConstCapture)
          ClassType.addConst();
        return ASTCtx.getPointerType(ClassType);
      }
      Closure = isLambdaCallOperator(Closure->getParent())
                    ? cast<CXXRecordDecl>(Closure->getParent()->getParent())
                    : nullptr;
    }
  }
  return ASTCtx.getPointerType(ClassType);
}
 
QualType Sema::getCurrentThisType() {
  DeclContext *DC = getFunctionLevelDeclContext();
  QualType ThisTy = CXXThisTypeOverride;
 
  if (CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(DC)) {
    if (method && method->isInstance())
      ThisTy = method->getThisType();
  }
 
  if (ThisTy.isNull() && isLambdaCallOperator(CurContext) &&
      inTemplateInstantiation() && isa<CXXRecordDecl>(DC)) {
 
    // This is a lambda call operator that is being instantiated as a default
    // initializer. DC must point to the enclosing class type, so we can recover
    // the 'this' type from it.
    QualType ClassTy = Context.getTypeDeclType(cast<CXXRecordDecl>(DC));
    // There are no cv-qualifiers for 'this' within default initializers,
    // per [expr.prim.general]p4.
    ThisTy = Context.getPointerType(ClassTy);
  }
 
  // If we are within a lambda's call operator, the cv-qualifiers of 'this'
  // might need to be adjusted if the lambda or any of its enclosing lambda's
  // captures '*this' by copy.
  if (!ThisTy.isNull() && isLambdaCallOperator(CurContext))
    return adjustCVQualifiersForCXXThisWithinLambda(FunctionScopes, ThisTy,
                                                    CurContext, Context);
  return ThisTy;
}
 
Sema::CXXThisScopeRAII::CXXThisScopeRAII(Sema &S,
                                         Decl *ContextDecl,
                                         Qualifiers CXXThisTypeQuals,
                                         bool Enabled)
  : S(S), OldCXXThisTypeOverride(S.CXXThisTypeOverride), Enabled(false)
{
  if (!Enabled || !ContextDecl)
    return;
 
  CXXRecordDecl *Record = nullptr;
  if (ClassTemplateDecl *Template = dyn_cast<ClassTemplateDecl>(ContextDecl))
    Record = Template->getTemplatedDecl();
  else
    Record = cast<CXXRecordDecl>(ContextDecl);
 
  QualType T = S.Context.getRecordType(Record);
  T = S.getASTContext().getQualifiedType(T, CXXThisTypeQuals);
 
  S.CXXThisTypeOverride = S.Context.getPointerType(T);
 
  this->Enabled = true;
}
 
 
Sema::CXXThisScopeRAII::~CXXThisScopeRAII() {
  if (Enabled) {
    S.CXXThisTypeOverride = OldCXXThisTypeOverride;
  }
}
 
static void buildLambdaThisCaptureFixit(Sema &Sema, LambdaScopeInfo *LSI) {
  SourceLocation DiagLoc = LSI->IntroducerRange.getEnd();
  assert(!LSI->isCXXThisCaptured());
  //  [=, this] {};   // until C++20: Error: this when = is the default
  if (LSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByval &&
      !Sema.getLangOpts().CPlusPlus20)
    return;
  Sema.Diag(DiagLoc, diag::note_lambda_this_capture_fixit)
      << FixItHint::CreateInsertion(
             DiagLoc, LSI->NumExplicitCaptures > 0 ? ", this" : "this");
}
 
bool Sema::CheckCXXThisCapture(SourceLocation Loc, const bool Explicit,
    bool BuildAndDiagnose, const unsigned *const FunctionScopeIndexToStopAt,
    const bool ByCopy) {
  // We don't need to capture this in an unevaluated context.
  if (isUnevaluatedContext() && !Explicit)
    return true;
 
  assert((!ByCopy || Explicit) && "cannot implicitly capture *this by value");
 
  const int MaxFunctionScopesIndex = FunctionScopeIndexToStopAt
                                         ? *FunctionScopeIndexToStopAt
                                         : FunctionScopes.size() - 1;
 
  // Check that we can capture the *enclosing object* (referred to by '*this')
  // by the capturing-entity/closure (lambda/block/etc) at
  // MaxFunctionScopesIndex-deep on the FunctionScopes stack.
 
  // Note: The *enclosing object* can only be captured by-value by a
  // closure that is a lambda, using the explicit notation:
  //    [*this] { ... }.
  // Every other capture of the *enclosing object* results in its by-reference
  // capture.
 
  // For a closure 'L' (at MaxFunctionScopesIndex in the FunctionScopes
  // stack), we can capture the *enclosing object* only if:
  // - 'L' has an explicit byref or byval capture of the *enclosing object*
  // -  or, 'L' has an implicit capture.
  // AND
  //   -- there is no enclosing closure
  //   -- or, there is some enclosing closure 'E' that has already captured the
  //      *enclosing object*, and every intervening closure (if any) between 'E'
  //      and 'L' can implicitly capture the *enclosing object*.
  //   -- or, every enclosing closure can implicitly capture the
  //      *enclosing object*
 
 
  unsigned NumCapturingClosures = 0;
  for (int idx = MaxFunctionScopesIndex; idx >= 0; idx--) {
    if (CapturingScopeInfo *CSI =
            dyn_cast<CapturingScopeInfo>(FunctionScopes[idx])) {
      if (CSI->CXXThisCaptureIndex != 0) {
        // 'this' is already being captured; there isn't anything more to do.
        CSI->Captures[CSI->CXXThisCaptureIndex - 1].markUsed(BuildAndDiagnose);
        break;
      }
      LambdaScopeInfo *LSI = dyn_cast<LambdaScopeInfo>(CSI);
      if (LSI && isGenericLambdaCallOperatorSpecialization(LSI->CallOperator)) {
        // This context can't implicitly capture 'this'; fail out.
        if (BuildAndDiagnose) {
          Diag(Loc, diag::err_this_capture)
              << (Explicit && idx == MaxFunctionScopesIndex);
          if (!Explicit)
            buildLambdaThisCaptureFixit(*this, LSI);
        }
        return true;
      }
      if (CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByref ||
          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByval ||
          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_Block ||
          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_CapturedRegion ||
          (Explicit && idx == MaxFunctionScopesIndex)) {
        // Regarding (Explicit && idx == MaxFunctionScopesIndex): only the first
        // iteration through can be an explicit capture, all enclosing closures,
        // if any, must perform implicit captures.
 
        // This closure can capture 'this'; continue looking upwards.
        NumCapturingClosures++;
        continue;
      }
      // This context can't implicitly capture 'this'; fail out.
      if (BuildAndDiagnose)
        Diag(Loc, diag::err_this_capture)
            << (Explicit && idx == MaxFunctionScopesIndex);
 
      if (!Explicit)
        buildLambdaThisCaptureFixit(*this, LSI);
      return true;
    }
    break;
  }
  if (!BuildAndDiagnose) return false;
 
  // If we got here, then the closure at MaxFunctionScopesIndex on the
  // FunctionScopes stack, can capture the *enclosing object*, so capture it
  // (including implicit by-reference captures in any enclosing closures).
 
  // In the loop below, respect the ByCopy flag only for the closure requesting
  // the capture (i.e. first iteration through the loop below).  Ignore it for
  // all enclosing closure's up to NumCapturingClosures (since they must be
  // implicitly capturing the *enclosing  object* by reference (see loop
  // above)).
  assert((!ByCopy ||
          dyn_cast<LambdaScopeInfo>(FunctionScopes[MaxFunctionScopesIndex])) &&
         "Only a lambda can capture the enclosing object (referred to by "
         "*this) by copy");
  QualType ThisTy = getCurrentThisType();
  for (int idx = MaxFunctionScopesIndex; NumCapturingClosures;
       --idx, --NumCapturingClosures) {
    CapturingScopeInfo *CSI = cast<CapturingScopeInfo>(FunctionScopes[idx]);
 
    // The type of the corresponding data member (not a 'this' pointer if 'by
    // copy').
    QualType CaptureType = ThisTy;
    if (ByCopy) {
      // If we are capturing the object referred to by '*this' by copy, ignore
      // any cv qualifiers inherited from the type of the member function for
      // the type of the closure-type's corresponding data member and any use
      // of 'this'.
      CaptureType = ThisTy->getPointeeType();
      CaptureType.removeLocalCVRQualifiers(Qualifiers::CVRMask);
    }
 
    bool isNested = NumCapturingClosures > 1;
    CSI->addThisCapture(isNested, Loc, CaptureType, ByCopy);
  }
  return false;
}
 
ExprResult Sema::ActOnCXXThis(SourceLocation Loc) {
  /// C++ 9.3.2: In the body of a non-static member function, the keyword this
  /// is a non-lvalue expression whose value is the address of the object for
  /// which the function is called.
 
  QualType ThisTy = getCurrentThisType();
  if (ThisTy.isNull())
    return Diag(Loc, diag::err_invalid_this_use);
  return BuildCXXThisExpr(Loc, ThisTy, /*IsImplicit=*/false);
}
 
Expr *Sema::BuildCXXThisExpr(SourceLocation Loc, QualType Type,
                             bool IsImplicit) {
  auto *This = new (Context) CXXThisExpr(Loc, Type, IsImplicit);
  MarkThisReferenced(This);
  return This;
}
 
void Sema::MarkThisReferenced(CXXThisExpr *This) {
  CheckCXXThisCapture(This->getExprLoc());
}
 
bool Sema::isThisOutsideMemberFunctionBody(QualType BaseType) {
  // If we're outside the body of a member function, then we'll have a specified
  // type for 'this'.
  if (CXXThisTypeOverride.isNull())
    return false;
 
  // Determine whether we're looking into a class that's currently being
  // defined.
  CXXRecordDecl *Class = BaseType->getAsCXXRecordDecl();
  return Class && Class->isBeingDefined();
}
 
/// Parse construction of a specified type.
/// Can be interpreted either as function-style casting ("int(x)")
/// or class type construction ("ClassType(x,y,z)")
/// or creation of a value-initialized type ("int()").
ExprResult
Sema::ActOnCXXTypeConstructExpr(ParsedType TypeRep,
                                SourceLocation LParenOrBraceLoc,
                                MultiExprArg exprs,
                                SourceLocation RParenOrBraceLoc,
                                bool ListInitialization) {
  if (!TypeRep)
    return ExprError();
 
  TypeSourceInfo *TInfo;
  QualType Ty = GetTypeFromParser(TypeRep, &TInfo);
  if (!TInfo)
    TInfo = Context.getTrivialTypeSourceInfo(Ty, SourceLocation());
 
  auto Result = BuildCXXTypeConstructExpr(TInfo, LParenOrBraceLoc, exprs,
                                          RParenOrBraceLoc, ListInitialization);
  // Avoid creating a non-type-dependent expression that contains typos.
  // Non-type-dependent expressions are liable to be discarded without
  // checking for embedded typos.
  if (!Result.isInvalid() && Result.get()->isInstantiationDependent() &&
      !Result.get()->isTypeDependent())
    Result = CorrectDelayedTyposInExpr(Result.get());
  else if (Result.isInvalid())
    Result = CreateRecoveryExpr(TInfo->getTypeLoc().getBeginLoc(),
                                RParenOrBraceLoc, exprs, Ty);
  return Result;
}
 
ExprResult
Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
                                SourceLocation LParenOrBraceLoc,
                                MultiExprArg Exprs,
                                SourceLocation RParenOrBraceLoc,
                                bool ListInitialization) {
  QualType Ty = TInfo->getType();
  SourceLocation TyBeginLoc = TInfo->getTypeLoc().getBeginLoc();
 
  assert((!ListInitialization ||
          (Exprs.size() == 1 && isa<InitListExpr>(Exprs[0]))) &&
         "List initialization must have initializer list as expression.");
  SourceRange FullRange = SourceRange(TyBeginLoc, RParenOrBraceLoc);
 
  InitializedEntity Entity =
      InitializedEntity::InitializeTemporary(Context, TInfo);
  InitializationKind Kind =
      Exprs.size()
          ? ListInitialization
                ? InitializationKind::CreateDirectList(
                      TyBeginLoc, LParenOrBraceLoc, RParenOrBraceLoc)
                : InitializationKind::CreateDirect(TyBeginLoc, LParenOrBraceLoc,
                                                   RParenOrBraceLoc)
          : InitializationKind::CreateValue(TyBeginLoc, LParenOrBraceLoc,
                                            RParenOrBraceLoc);
 
  // C++1z [expr.type.conv]p1:
  //   If the type is a placeholder for a deduced class type, [...perform class
  //   template argument deduction...]
  DeducedType *Deduced = Ty->getContainedDeducedType();
  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
    Ty = DeduceTemplateSpecializationFromInitializer(TInfo, Entity,
                                                     Kind, Exprs);
    if (Ty.isNull())
      return ExprError();
    Entity = InitializedEntity::InitializeTemporary(TInfo, Ty);
  }
 
  if (Ty->isDependentType() || CallExpr::hasAnyTypeDependentArguments(Exprs)) {
    // FIXME: CXXUnresolvedConstructExpr does not model list-initialization
    // directly. We work around this by dropping the locations of the braces.
    SourceRange Locs = ListInitialization
                           ? SourceRange()
                           : SourceRange(LParenOrBraceLoc, RParenOrBraceLoc);
    return CXXUnresolvedConstructExpr::Create(Context, Ty.getNonReferenceType(),
                                              TInfo, Locs.getBegin(), Exprs,
                                              Locs.getEnd());
  }
 
  // C++ [expr.type.conv]p1:
  // If the expression list is a parenthesized single expression, the type
  // conversion expression is equivalent (in definedness, and if defined in
  // meaning) to the corresponding cast expression.
  if (Exprs.size() == 1 && !ListInitialization &&
      !isa<InitListExpr>(Exprs[0])) {
    Expr *Arg = Exprs[0];
    return BuildCXXFunctionalCastExpr(TInfo, Ty, LParenOrBraceLoc, Arg,
                                      RParenOrBraceLoc);
  }
 
  //   For an expression of the form T(), T shall not be an array type.
  QualType ElemTy = Ty;
  if (Ty->isArrayType()) {
    if (!ListInitialization)
      return ExprError(Diag(TyBeginLoc, diag::err_value_init_for_array_type)
                         << FullRange);
    ElemTy = Context.getBaseElementType(Ty);
  }
 
  // Only construct objects with object types.
  // The standard doesn't explicitly forbid function types here, but that's an
  // obvious oversight, as there's no way to dynamically construct a function
  // in general.
  if (Ty->isFunctionType())
    return ExprError(Diag(TyBeginLoc, diag::err_init_for_function_type)
                       << Ty << FullRange);
 
  // C++17 [expr.type.conv]p2:
  //   If the type is cv void and the initializer is (), the expression is a
  //   prvalue of the specified type that performs no initialization.
  if (!Ty->isVoidType() &&
      RequireCompleteType(TyBeginLoc, ElemTy,
                          diag::err_invalid_incomplete_type_use, FullRange))
    return ExprError();
 
  //   Otherwise, the expression is a prvalue of the specified type whose
  //   result object is direct-initialized (11.6) with the initializer.
  InitializationSequence InitSeq(*this, Entity, Kind, Exprs);
  ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Exprs);
 
  if (Result.isInvalid())
    return Result;
 
  Expr *Inner = Result.get();
  if (CXXBindTemporaryExpr *BTE = dyn_cast_or_null<CXXBindTemporaryExpr>(Inner))
    Inner = BTE->getSubExpr();
  if (!isa<CXXTemporaryObjectExpr>(Inner) &&
      !isa<CXXScalarValueInitExpr>(Inner)) {
    // If we created a CXXTemporaryObjectExpr, that node also represents the
    // functional cast. Otherwise, create an explicit cast to represent
    // the syntactic form of a functional-style cast that was used here.
    //
    // FIXME: Creating a CXXFunctionalCastExpr around a CXXConstructExpr
    // would give a more consistent AST representation than using a
    // CXXTemporaryObjectExpr. It's also weird that the functional cast
    // is sometimes handled by initialization and sometimes not.
    QualType ResultType = Result.get()->getType();
    SourceRange Locs = ListInitialization
                           ? SourceRange()
                           : SourceRange(LParenOrBraceLoc, RParenOrBraceLoc);
    Result = CXXFunctionalCastExpr::Create(
        Context, ResultType, Expr::getValueKindForType(Ty), TInfo, CK_NoOp,
        Result.get(), /*Path=*/nullptr, CurFPFeatureOverrides(),
        Locs.getBegin(), Locs.getEnd());
  }
 
  return Result;
}
 
bool Sema::isUsualDeallocationFunction(const CXXMethodDecl *Method) {
  // [CUDA] Ignore this function, if we can't call it.
  const FunctionDecl *Caller = dyn_cast<FunctionDecl>(CurContext);
  if (getLangOpts().CUDA) {
    auto CallPreference = IdentifyCUDAPreference(Caller, Method);
    // If it's not callable at all, it's not the right function.
    if (CallPreference < CFP_WrongSide)
      return false;
    if (CallPreference == CFP_WrongSide) {
      // Maybe. We have to check if there are better alternatives.
      DeclContext::lookup_result R =
          Method->getDeclContext()->lookup(Method->getDeclName());
      for (const auto *D : R) {
        if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
          if (IdentifyCUDAPreference(Caller, FD) > CFP_WrongSide)
            return false;
        }
      }
      // We've found no better variants.
    }
  }
 
  SmallVector<const FunctionDecl*, 4> PreventedBy;
  bool Result = Method->isUsualDeallocationFunction(PreventedBy);
 
  if (Result || !getLangOpts().CUDA || PreventedBy.empty())
    return Result;
 
  // In case of CUDA, return true if none of the 1-argument deallocator
  // functions are actually callable.
  return llvm::none_of(PreventedBy, [&](const FunctionDecl *FD) {
    assert(FD->getNumParams() == 1 &&
           "Only single-operand functions should be in PreventedBy");
    return IdentifyCUDAPreference(Caller, FD) >= CFP_HostDevice;
  });
}
 
/// Determine whether the given function is a non-placement
/// deallocation function.
static bool isNonPlacementDeallocationFunction(Sema &S, FunctionDecl *FD) {
  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FD))
    return S.isUsualDeallocationFunction(Method);
 
  if (FD->getOverloadedOperator() != OO_Delete &&
      FD->getOverloadedOperator() != OO_Array_Delete)
    return false;
 
  unsigned UsualParams = 1;
 
  if (S.getLangOpts().SizedDeallocation && UsualParams < FD->getNumParams() &&
      S.Context.hasSameUnqualifiedType(
          FD->getParamDecl(UsualParams)->getType(),
          S.Context.getSizeType()))
    ++UsualParams;
 
  if (S.getLangOpts().AlignedAllocation && UsualParams < FD->getNumParams() &&
      S.Context.hasSameUnqualifiedType(
          FD->getParamDecl(UsualParams)->getType(),
          S.Context.getTypeDeclType(S.getStdAlignValT())))
    ++UsualParams;
 
  return UsualParams == FD->getNumParams();
}
 
namespace {
  struct UsualDeallocFnInfo {
    UsualDeallocFnInfo() : Found(), FD(nullptr) {}
    UsualDeallocFnInfo(Sema &S, DeclAccessPair Found)
        : Found(Found), FD(dyn_cast<FunctionDecl>(Found->getUnderlyingDecl())),
          Destroying(false), HasSizeT(false), HasAlignValT(false),
          CUDAPref(Sema::CFP_Native) {
      // A function template declaration is never a usual deallocation function.
      if (!FD)
        return;
      unsigned NumBaseParams = 1;
      if (FD->isDestroyingOperatorDelete()) {
        Destroying = true;
        ++NumBaseParams;
      }
 
      if (NumBaseParams < FD->getNumParams() &&
          S.Context.hasSameUnqualifiedType(
              FD->getParamDecl(NumBaseParams)->getType(),
              S.Context.getSizeType())) {
        ++NumBaseParams;
        HasSizeT = true;
      }
 
      if (NumBaseParams < FD->getNumParams() &&
          FD->getParamDecl(NumBaseParams)->getType()->isAlignValT()) {
        ++NumBaseParams;
        HasAlignValT = true;
      }
 
      // In CUDA, determine how much we'd like / dislike to call this.
      if (S.getLangOpts().CUDA)
        if (auto *Caller = dyn_cast<FunctionDecl>(S.CurContext))
          CUDAPref = S.IdentifyCUDAPreference(Caller, FD);
    }
 
    explicit operator bool() const { return FD; }
 
    bool isBetterThan(const UsualDeallocFnInfo &Other, bool WantSize,
                      bool WantAlign) const {
      // C++ P0722:
      //   A destroying operator delete is preferred over a non-destroying
      //   operator delete.
      if (Destroying != Other.Destroying)
        return Destroying;
 
      // C++17 [expr.delete]p10:
      //   If the type has new-extended alignment, a function with a parameter
      //   of type std::align_val_t is preferred; otherwise a function without
      //   such a parameter is preferred
      if (HasAlignValT != Other.HasAlignValT)
        return HasAlignValT == WantAlign;
 
      if (HasSizeT != Other.HasSizeT)
        return HasSizeT == WantSize;
 
      // Use CUDA call preference as a tiebreaker.
      return CUDAPref > Other.CUDAPref;
    }
 
    DeclAccessPair Found;
    FunctionDecl *FD;
    bool Destroying, HasSizeT, HasAlignValT;
    Sema::CUDAFunctionPreference CUDAPref;
  };
}
 
/// Determine whether a type has new-extended alignment. This may be called when
/// the type is incomplete (for a delete-expression with an incomplete pointee
/// type), in which case it will conservatively return false if the alignment is
/// not known.
static bool hasNewExtendedAlignment(Sema &S, QualType AllocType) {
  return S.getLangOpts().AlignedAllocation &&
         S.getASTContext().getTypeAlignIfKnown(AllocType) >
             S.getASTContext().getTargetInfo().getNewAlign();
}
 
/// Select the correct "usual" deallocation function to use from a selection of
/// deallocation functions (either global or class-scope).
static UsualDeallocFnInfo resolveDeallocationOverload(
    Sema &S, LookupResult &R, bool WantSize, bool WantAlign,
    llvm::SmallVectorImpl<UsualDeallocFnInfo> *BestFns = nullptr) {
  UsualDeallocFnInfo Best;
 
  for (auto I = R.begin(), E = R.end(); I != E; ++I) {
    UsualDeallocFnInfo Info(S, I.getPair());
    if (!Info || !isNonPlacementDeallocationFunction(S, Info.FD) ||
        Info.CUDAPref == Sema::CFP_Never)
      continue;
 
    if (!Best) {
      Best = Info;
      if (BestFns)
        BestFns->push_back(Info);
      continue;
    }
 
    if (Best.isBetterThan(Info, WantSize, WantAlign))
      continue;
 
    //   If more than one preferred function is found, all non-preferred
    //   functions are eliminated from further consideration.
    if (BestFns && Info.isBetterThan(Best, WantSize, WantAlign))
      BestFns->clear();
 
    Best = Info;
    if (BestFns)
      BestFns->push_back(Info);
  }
 
  return Best;
}
 
/// Determine whether a given type is a class for which 'delete[]' would call
/// a member 'operator delete[]' with a 'size_t' parameter. This implies that
/// we need to store the array size (even if the type is
/// trivially-destructible).
static bool doesUsualArrayDeleteWantSize(Sema &S, SourceLocation loc,
                                         QualType allocType) {
  const RecordType *record =
    allocType->getBaseElementTypeUnsafe()->getAs<RecordType>();
  if (!record) return false;
 
  // Try to find an operator delete[] in class scope.
 
  DeclarationName deleteName =
    S.Context.DeclarationNames.getCXXOperatorName(OO_Array_Delete);
  LookupResult ops(S, deleteName, loc, Sema::LookupOrdinaryName);
  S.LookupQualifiedName(ops, record->getDecl());
 
  // We're just doing this for information.
  ops.suppressDiagnostics();
 
  // Very likely: there's no operator delete[].
  if (ops.empty()) return false;
 
  // If it's ambiguous, it should be illegal to call operator delete[]
  // on this thing, so it doesn't matter if we allocate extra space or not.
  if (ops.isAmbiguous()) return false;
 
  // C++17 [expr.delete]p10:
  //   If the deallocation functions have class scope, the one without a
  //   parameter of type std::size_t is selected.
  auto Best = resolveDeallocationOverload(
      S, ops, /*WantSize*/false,
      /*WantAlign*/hasNewExtendedAlignment(S, allocType));
  return Best && Best.HasSizeT;
}
 
/// Parsed a C++ 'new' expression (C++ 5.3.4).
///
/// E.g.:
/// @code new (memory) int[size][4] @endcode
/// or
/// @code ::new Foo(23, "hello") @endcode
///
/// \param StartLoc The first location of the expression.
/// \param UseGlobal True if 'new' was prefixed with '::'.
/// \param PlacementLParen Opening paren of the placement arguments.
/// \param PlacementArgs Placement new arguments.
/// \param PlacementRParen Closing paren of the placement arguments.
/// \param TypeIdParens If the type is in parens, the source range.
/// \param D The type to be allocated, as well as array dimensions.
/// \param Initializer The initializing expression or initializer-list, or null
///   if there is none.
ExprResult
Sema::ActOnCXXNew(SourceLocation StartLoc, bool UseGlobal,
                  SourceLocation PlacementLParen, MultiExprArg PlacementArgs,
                  SourceLocation PlacementRParen, SourceRange TypeIdParens,
                  Declarator &D, Expr *Initializer) {
  Optional<Expr *> ArraySize;
  // If the specified type is an array, unwrap it and save the expression.
  if (D.getNumTypeObjects() > 0 &&
      D.getTypeObject(0).Kind == DeclaratorChunk::Array) {
    DeclaratorChunk &Chunk = D.getTypeObject(0);
    if (D.getDeclSpec().hasAutoTypeSpec())
      return ExprError(Diag(Chunk.Loc, diag::err_new_array_of_auto)
        << D.getSourceRange());
    if (Chunk.Arr.hasStatic)
      return ExprError(Diag(Chunk.Loc, diag::err_static_illegal_in_new)
        << D.getSourceRange());
    if (!Chunk.Arr.NumElts && !Initializer)
      return ExprError(Diag(Chunk.Loc, diag::err_array_new_needs_size)
        << D.getSourceRange());
 
    ArraySize = static_cast<Expr*>(Chunk.Arr.NumElts);
    D.DropFirstTypeObject();
  }
 
  // Every dimension shall be of constant size.
  if (ArraySize) {
    for (unsigned I = 0, N = D.getNumTypeObjects(); I < N; ++I) {
      if (D.getTypeObject(I).Kind != DeclaratorChunk::Array)
        break;
 
      DeclaratorChunk::ArrayTypeInfo &Array = D.getTypeObject(I).Arr;
      if (Expr *NumElts = (Expr *)Array.NumElts) {
        if (!NumElts->isTypeDependent() && !NumElts->isValueDependent()) {
          // FIXME: GCC permits constant folding here. We should either do so consistently
          // or not do so at all, rather than changing behavior in C++14 onwards.
          if (getLangOpts().CPlusPlus14) {
            // C++1y [expr.new]p6: Every constant-expression in a noptr-new-declarator
            //   shall be a converted constant expression (5.19) of type std::size_t
            //   and shall evaluate to a strictly positive value.
            llvm::APSInt Value(Context.getIntWidth(Context.getSizeType()));
            Array.NumElts
             = CheckConvertedConstantExpression(NumElts, Context.getSizeType(), Value,
                                                CCEK_ArrayBound)
                 .get();
          } else {
            Array.NumElts =
                VerifyIntegerConstantExpression(
                    NumElts, nullptr, diag::err_new_array_nonconst, AllowFold)
                    .get();
          }
          if (!Array.NumElts)
            return ExprError();
        }
      }
    }
  }
 
  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, /*Scope=*/nullptr);
  QualType AllocType = TInfo->getType();
  if (D.isInvalidType())
    return ExprError();
 
  SourceRange DirectInitRange;
  if (ParenListExpr *List = dyn_cast_or_null<ParenListExpr>(Initializer))
    DirectInitRange = List->getSourceRange();
 
  return BuildCXXNew(SourceRange(StartLoc, D.getEndLoc()), UseGlobal,
                     PlacementLParen, PlacementArgs, PlacementRParen,
                     TypeIdParens, AllocType, TInfo, ArraySize, DirectInitRange,
                     Initializer);
}
 
static bool isLegalArrayNewInitializer(CXXNewExpr::InitializationStyle Style,
                                       Expr *Init) {
  if (!Init)
    return true;
  if (ParenListExpr *PLE = dyn_cast<ParenListExpr>(Init))
    return PLE->getNumExprs() == 0;
  if (isa<ImplicitValueInitExpr>(Init))
    return true;
  else if (CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Init))
    return !CCE->isListInitialization() &&
           CCE->getConstructor()->isDefaultConstructor();
  else if (Style == CXXNewExpr::ListInit) {
    assert(isa<InitListExpr>(Init) &&
           "Shouldn't create list CXXConstructExprs for arrays.");
    return true;
  }
  return false;
}
 
bool
Sema::isUnavailableAlignedAllocationFunction(const FunctionDecl &FD) const {
  if (!getLangOpts().AlignedAllocationUnavailable)
    return false;
  if (FD.isDefined())
    return false;
  Optional<unsigned> AlignmentParam;
  if (FD.isReplaceableGlobalAllocationFunction(&AlignmentParam) &&
      AlignmentParam.hasValue())
    return true;
  return false;
}
 
// Emit a diagnostic if an aligned allocation/deallocation function that is not
// implemented in the standard library is selected.
void Sema::diagnoseUnavailableAlignedAllocation(const FunctionDecl &FD,
                                                SourceLocation Loc) {
  if (isUnavailableAlignedAllocationFunction(FD)) {
    const llvm::Triple &T = getASTContext().getTargetInfo().getTriple();
    StringRef OSName = AvailabilityAttr::getPlatformNameSourceSpelling(
        getASTContext().getTargetInfo().getPlatformName());
    VersionTuple OSVersion = alignedAllocMinVersion(T.getOS());
 
    OverloadedOperatorKind Kind = FD.getDeclName().getCXXOverloadedOperator();
    bool IsDelete = Kind == OO_Delete || Kind == OO_Array_Delete;
    Diag(Loc, diag::err_aligned_allocation_unavailable)
        << IsDelete << FD.getType().getAsString() << OSName
        << OSVersion.getAsString() << OSVersion.empty();
    Diag(Loc, diag::note_silence_aligned_allocation_unavailable);
  }
}
 
ExprResult
Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
                  SourceLocation PlacementLParen,
                  MultiExprArg PlacementArgs,
                  SourceLocation PlacementRParen,
                  SourceRange TypeIdParens,
                  QualType AllocType,
                  TypeSourceInfo *AllocTypeInfo,
                  Optional<Expr *> ArraySize,
                  SourceRange DirectInitRange,
                  Expr *Initializer) {
  SourceRange TypeRange = AllocTypeInfo->getTypeLoc().getSourceRange();
  SourceLocation StartLoc = Range.getBegin();
 
  CXXNewExpr::InitializationStyle initStyle;
  if (DirectInitRange.isValid()) {
    assert(Initializer && "Have parens but no initializer.");
    initStyle = CXXNewExpr::CallInit;
  } else if (Initializer && isa<InitListExpr>(Initializer))
    initStyle = CXXNewExpr::ListInit;
  else {
    assert((!Initializer || isa<ImplicitValueInitExpr>(Initializer) ||
            isa<CXXConstructExpr>(Initializer)) &&
           "Initializer expression that cannot have been implicitly created.");
    initStyle = CXXNewExpr::NoInit;
  }
 
  Expr **Inits = &Initializer;
  unsigned NumInits = Initializer ? 1 : 0;
  if (ParenListExpr *List = dyn_cast_or_null<ParenListExpr>(Initializer)) {
    assert(initStyle == CXXNewExpr::CallInit && "paren init for non-call init");
    Inits = List->getExprs();
    NumInits = List->getNumExprs();
  }
 
  // C++11 [expr.new]p15:
  //   A new-expression that creates an object of type T initializes that
  //   object as follows:
  InitializationKind Kind
      //     - If the new-initializer is omitted, the object is default-
      //       initialized (8.5); if no initialization is performed,
      //       the object has indeterminate value
      = initStyle == CXXNewExpr::NoInit
            ? InitializationKind::CreateDefault(TypeRange.getBegin())
            //     - Otherwise, the new-initializer is interpreted according to
            //     the
            //       initialization rules of 8.5 for direct-initialization.
            : initStyle == CXXNewExpr::ListInit
                  ? InitializationKind::CreateDirectList(
                        TypeRange.getBegin(), Initializer->getBeginLoc(),
                        Initializer->getEndLoc())
                  : InitializationKind::CreateDirect(TypeRange.getBegin(),
                                                     DirectInitRange.getBegin(),
                                                     DirectInitRange.getEnd());
 
  // C++11 [dcl.spec.auto]p6. Deduce the type which 'auto' stands in for.
  auto *Deduced = AllocType->getContainedDeducedType();
  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
    if (ArraySize)
      return ExprError(
          Diag(*ArraySize ? (*ArraySize)->getExprLoc() : TypeRange.getBegin(),
               diag::err_deduced_class_template_compound_type)
          << /*array*/ 2
          << (*ArraySize ? (*ArraySize)->getSourceRange() : TypeRange));
 
    InitializedEntity Entity
      = InitializedEntity::InitializeNew(StartLoc, AllocType);
    AllocType = DeduceTemplateSpecializationFromInitializer(
        AllocTypeInfo, Entity, Kind, MultiExprArg(Inits, NumInits));
    if (AllocType.isNull())
      return ExprError();
  } else if (Deduced) {
    bool Braced = (initStyle == CXXNewExpr::ListInit);
    if (NumInits == 1) {
      if (auto p = dyn_cast_or_null<InitListExpr>(Inits[0])) {
        Inits = p->getInits();
        NumInits = p->getNumInits();
        Braced = true;
      }
    }
 
    if (initStyle == CXXNewExpr::NoInit || NumInits == 0)
      return ExprError(Diag(StartLoc, diag::err_auto_new_requires_ctor_arg)
                       << AllocType << TypeRange);
    if (NumInits > 1) {
      Expr *FirstBad = Inits[1];
      return ExprError(Diag(FirstBad->getBeginLoc(),
                            diag::err_auto_new_ctor_multiple_expressions)
                       << AllocType << TypeRange);
    }
    if (Braced && !getLangOpts().CPlusPlus17)
      Diag(Initializer->getBeginLoc(), diag::ext_auto_new_list_init)
          << AllocType << TypeRange;
    Expr *Deduce = Inits[0];
    QualType DeducedType;
    if (DeduceAutoType(AllocTypeInfo, Deduce, DeducedType) == DAR_Failed)
      return ExprError(Diag(StartLoc, diag::err_auto_new_deduction_failure)
                       << AllocType << Deduce->getType()
                       << TypeRange << Deduce->getSourceRange());
    if (DeducedType.isNull())
      return ExprError();
    AllocType = DeducedType;
  }
 
  // Per C++0x [expr.new]p5, the type being constructed may be a
  // typedef of an array type.
  if (!ArraySize) {
    if (const ConstantArrayType *Array
                              = Context.getAsConstantArrayType(AllocType)) {
      ArraySize = IntegerLiteral::Create(Context, Array->getSize(),
                                         Context.getSizeType(),
                                         TypeRange.getEnd());
      AllocType = Array->getElementType();
    }
  }
 
  if (CheckAllocatedType(AllocType, TypeRange.getBegin(), TypeRange))
    return ExprError();
 
  // In ARC, infer 'retaining' for the allocated
  if (getLangOpts().ObjCAutoRefCount &&
      AllocType.getObjCLifetime() == Qualifiers::OCL_None &&
      AllocType->isObjCLifetimeType()) {
    AllocType = Context.getLifetimeQualifiedType(AllocType,
                                    AllocType->getObjCARCImplicitLifetime());
  }
 
  QualType ResultType = Context.getPointerType(AllocType);
 
  if (ArraySize && *ArraySize &&
      (*ArraySize)->getType()->isNonOverloadPlaceholderType()) {
    ExprResult result = CheckPlaceholderExpr(*ArraySize);
    if (result.isInvalid()) return ExprError();
    ArraySize = result.get();
  }
  // C++98 5.3.4p6: "The expression in a direct-new-declarator shall have
  //   integral or enumeration type with a non-negative value."
  // C++11 [expr.new]p6: The expression [...] shall be of integral or unscoped
  //   enumeration type, or a class type for which a single non-explicit
  //   conversion function to integral or unscoped enumeration type exists.
  // C++1y [expr.new]p6: The expression [...] is implicitly converted to
  //   std::size_t.
  llvm::Optional<uint64_t> KnownArraySize;
  if (ArraySize && *ArraySize && !(*ArraySize)->isTypeDependent()) {
    ExprResult ConvertedSize;
    if (getLangOpts().CPlusPlus14) {
      assert(Context.getTargetInfo().getIntWidth() && "Builtin type of size 0?");
 
      ConvertedSize = PerformImplicitConversion(*ArraySize, Context.getSizeType(),
                                                AA_Converting);
 
      if (!ConvertedSize.isInvalid() &&
          (*ArraySize)->getType()->getAs<RecordType>())
        // Diagnose the compatibility of this conversion.
        Diag(StartLoc, diag::warn_cxx98_compat_array_size_conversion)
          << (*ArraySize)->getType() << 0 << "'size_t'";
    } else {
      class SizeConvertDiagnoser : public ICEConvertDiagnoser {
      protected:
        Expr *ArraySize;
 
      public:
        SizeConvertDiagnoser(Expr *ArraySize)
            : ICEConvertDiagnoser(/*AllowScopedEnumerations*/false, false, false),
              ArraySize(ArraySize) {}
 
        SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
                                             QualType T) override {
          return S.Diag(Loc, diag::err_array_size_not_integral)
                   << S.getLangOpts().CPlusPlus11 << T;
        }
 
        SemaDiagnosticBuilder diagnoseIncomplete(
            Sema &S, SourceLocation Loc, QualType T) override {
          return S.Diag(Loc, diag::err_array_size_incomplete_type)
                   << T << ArraySize->getSourceRange();
        }
 
        SemaDiagnosticBuilder diagnoseExplicitConv(
            Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
          return S.Diag(Loc, diag::err_array_size_explicit_conversion) << T << ConvTy;
        }
 
        SemaDiagnosticBuilder noteExplicitConv(
            Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
          return S.Diag(Conv->getLocation(), diag::note_array_size_conversion)
                   << ConvTy->isEnumeralType() << ConvTy;
        }
 
        SemaDiagnosticBuilder diagnoseAmbiguous(
            Sema &S, SourceLocation Loc, QualType T) override {
          return S.Diag(Loc, diag::err_array_size_ambiguous_conversion) << T;
        }
 
        SemaDiagnosticBuilder noteAmbiguous(
            Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
          return S.Diag(Conv->getLocation(), diag::note_array_size_conversion)
                   << ConvTy->isEnumeralType() << ConvTy;
        }
 
        SemaDiagnosticBuilder diagnoseConversion(Sema &S, SourceLocation Loc,
                                                 QualType T,
                                                 QualType ConvTy) override {
          return S.Diag(Loc,
                        S.getLangOpts().CPlusPlus11
                          ? diag::warn_cxx98_compat_array_size_conversion
                          : diag::ext_array_size_conversion)
                   << T << ConvTy->isEnumeralType() << ConvTy;
        }
      } SizeDiagnoser(*ArraySize);
 
      ConvertedSize = PerformContextualImplicitConversion(StartLoc, *ArraySize,
                                                          SizeDiagnoser);
    }
    if (ConvertedSize.isInvalid())
      return ExprError();
 
    ArraySize = ConvertedSize.get();
    QualType SizeType = (*ArraySize)->getType();
 
    if (!SizeType->isIntegralOrUnscopedEnumerationType())
      return ExprError();
 
    // C++98 [expr.new]p7:
    //   The expression in a direct-new-declarator shall have integral type
    //   with a non-negative value.
    //
    // Let's see if this is a constant < 0. If so, we reject it out of hand,
    // per CWG1464. Otherwise, if it's not a constant, we must have an
    // unparenthesized array type.
 
    // We've already performed any required implicit conversion to integer or
    // unscoped enumeration type.
    // FIXME: Per CWG1464, we are required to check the value prior to
    // converting to size_t. This will never find a negative array size in
    // C++14 onwards, because Value is always unsigned here!
    if (Optional<llvm::APSInt> Value =
            (*ArraySize)->getIntegerConstantExpr(Context)) {
      if (Value->isSigned() && Value->isNegative()) {
        return ExprError(Diag((*ArraySize)->getBeginLoc(),
                              diag::err_typecheck_negative_array_size)
                         << (*ArraySize)->getSourceRange());
      }
 
      if (!AllocType->isDependentType()) {
        unsigned ActiveSizeBits =
            ConstantArrayType::getNumAddressingBits(Context, AllocType, *Value);
        if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context))
          return ExprError(
              Diag((*ArraySize)->getBeginLoc(), diag::err_array_too_large)
              << toString(*Value, 10) << (*ArraySize)->getSourceRange());
      }
 
      KnownArraySize = Value->getZExtValue();
    } else if (TypeIdParens.isValid()) {
      // Can't have dynamic array size when the type-id is in parentheses.
      Diag((*ArraySize)->getBeginLoc(), diag::ext_new_paren_array_nonconst)
          << (*ArraySize)->getSourceRange()
          << FixItHint::CreateRemoval(TypeIdParens.getBegin())
          << FixItHint::CreateRemoval(TypeIdParens.getEnd());
 
      TypeIdParens = SourceRange();
    }
 
    // Note that we do *not* convert the argument in any way.  It can
    // be signed, larger than size_t, whatever.
  }
 
  FunctionDecl *OperatorNew = nullptr;
  FunctionDecl *OperatorDelete = nullptr;
  unsigned Alignment =
      AllocType->isDependentType() ? 0 : Context.getTypeAlign(AllocType);
  unsigned NewAlignment = Context.getTargetInfo().getNewAlign();
  bool PassAlignment = getLangOpts().AlignedAllocation &&
                       Alignment > NewAlignment;
 
  AllocationFunctionScope Scope = UseGlobal ? AFS_Global : AFS_Both;
  if (!AllocType->isDependentType() &&
      !Expr::hasAnyTypeDependentArguments(PlacementArgs) &&
      FindAllocationFunctions(
          StartLoc, SourceRange(PlacementLParen, PlacementRParen), Scope, Scope,
          AllocType, ArraySize.hasValue(), PassAlignment, PlacementArgs,
          OperatorNew, OperatorDelete))
    return ExprError();
 
  // If this is an array allocation, compute whether the usual array
  // deallocation function for the type has a size_t parameter.
  bool UsualArrayDeleteWantsSize = false;
  if (ArraySize && !AllocType->isDependentType())
    UsualArrayDeleteWantsSize =
        doesUsualArrayDeleteWantSize(*this, StartLoc, AllocType);
 
  SmallVector<Expr *, 8> AllPlaceArgs;
  if (OperatorNew) {
    auto *Proto = OperatorNew->getType()->castAs<FunctionProtoType>();
    VariadicCallType CallType = Proto->isVariadic() ? VariadicFunction
                                                    : VariadicDoesNotApply;
 
    // We've already converted the placement args, just fill in any default
    // arguments. Skip the first parameter because we don't have a corresponding
    // argument. Skip the second parameter too if we're passing in the
    // alignment; we've already filled it in.
    unsigned NumImplicitArgs = PassAlignment ? 2 : 1;
    if (GatherArgumentsForCall(PlacementLParen, OperatorNew, Proto,
                               NumImplicitArgs, PlacementArgs, AllPlaceArgs,
                               CallType))
      return ExprError();
 
    if (!AllPlaceArgs.empty())
      PlacementArgs = AllPlaceArgs;
 
    // We would like to perform some checking on the given `operator new` call,
    // but the PlacementArgs does not contain the implicit arguments,
    // namely allocation size and maybe allocation alignment,
    // so we need to conjure them.
 
    QualType SizeTy = Context.getSizeType();
    unsigned SizeTyWidth = Context.getTypeSize(SizeTy);
 
    llvm::APInt SingleEltSize(
        SizeTyWidth, Context.getTypeSizeInChars(AllocType).getQuantity());
 
    // How many bytes do we want to allocate here?
    llvm::Optional<llvm::APInt> AllocationSize;
    if (!ArraySize.hasValue() && !AllocType->isDependentType()) {
      // For non-array operator new, we only want to allocate one element.
      AllocationSize = SingleEltSize;
    } else if (KnownArraySize.hasValue() && !AllocType->isDependentType()) {
      // For array operator new, only deal with static array size case.
      bool Overflow;
      AllocationSize = llvm::APInt(SizeTyWidth, *KnownArraySize)
                           .umul_ov(SingleEltSize, Overflow);
      (void)Overflow;
      assert(
          !Overflow &&
          "Expected that all the overflows would have been handled already.");
    }
 
    IntegerLiteral AllocationSizeLiteral(
        Context, AllocationSize.getValueOr(llvm::APInt::getZero(SizeTyWidth)),
        SizeTy, SourceLocation());
    // Otherwise, if we failed to constant-fold the allocation size, we'll
    // just give up and pass-in something opaque, that isn't a null pointer.
    OpaqueValueExpr OpaqueAllocationSize(SourceLocation(), SizeTy, VK_PRValue,
                                         OK_Ordinary, /*SourceExpr=*/nullptr);
 
    // Let's synthesize the alignment argument in case we will need it.
    // Since we *really* want to allocate these on stack, this is slightly ugly
    // because there might not be a `std::align_val_t` type.
    EnumDecl *StdAlignValT = getStdAlignValT();
    QualType AlignValT =
        StdAlignValT ? Context.getTypeDeclType(StdAlignValT) : SizeTy;
    IntegerLiteral AlignmentLiteral(
        Context,
        llvm::APInt(Context.getTypeSize(SizeTy),
                    Alignment / Context.getCharWidth()),
        SizeTy, SourceLocation());
    ImplicitCastExpr DesiredAlignment(ImplicitCastExpr::OnStack, AlignValT,
                                      CK_IntegralCast, &AlignmentLiteral,
                                      VK_PRValue, FPOptionsOverride());
 
    // Adjust placement args by prepending conjured size and alignment exprs.
    llvm::SmallVector<Expr *, 8> CallArgs;
    CallArgs.reserve(NumImplicitArgs + PlacementArgs.size());
    CallArgs.emplace_back(AllocationSize.hasValue()
                              ? static_cast<Expr *>(&AllocationSizeLiteral)
                              : &OpaqueAllocationSize);
    if (PassAlignment)
      CallArgs.emplace_back(&DesiredAlignment);
    CallArgs.insert(CallArgs.end(), PlacementArgs.begin(), PlacementArgs.end());
 
    DiagnoseSentinelCalls(OperatorNew, PlacementLParen, CallArgs);
 
    checkCall(OperatorNew, Proto, /*ThisArg=*/nullptr, CallArgs,
              /*IsMemberFunction=*/false, StartLoc, Range, CallType);
 
    // Warn if the type is over-aligned and is being allocated by (unaligned)
    // global operator new.
    if (PlacementArgs.empty() && !PassAlignment &&
        (OperatorNew->isImplicit() ||
         (OperatorNew->getBeginLoc().isValid() &&
          getSourceManager().isInSystemHeader(OperatorNew->getBeginLoc())))) {
      if (Alignment > NewAlignment)
        Diag(StartLoc, diag::warn_overaligned_type)
            << AllocType
            << unsigned(Alignment / Context.getCharWidth())
            << unsigned(NewAlignment / Context.getCharWidth());
    }
  }
 
  // Array 'new' can't have any initializers except empty parentheses.
  // Initializer lists are also allowed, in C++11. Rely on the parser for the
  // dialect distinction.
  if (ArraySize && !isLegalArrayNewInitializer(initStyle, Initializer)) {
    SourceRange InitRange(Inits[0]->getBeginLoc(),
                          Inits[NumInits - 1]->getEndLoc());
    Diag(StartLoc, diag::err_new_array_init_args) << InitRange;
    return ExprError();
  }
 
  // If we can perform the initialization, and we've not already done so,
  // do it now.
  if (!AllocType->isDependentType() &&
      !Expr::hasAnyTypeDependentArguments(
          llvm::makeArrayRef(Inits, NumInits))) {
    // The type we initialize is the complete type, including the array bound.
    QualType InitType;
    if (KnownArraySize)
      InitType = Context.getConstantArrayType(
          AllocType,
          llvm::APInt(Context.getTypeSize(Context.getSizeType()),
                      *KnownArraySize),
          *ArraySize, ArrayType::Normal, 0);
    else if (ArraySize)
      InitType =
          Context.getIncompleteArrayType(AllocType, ArrayType::Normal, 0);
    else
      InitType = AllocType;
 
    InitializedEntity Entity
      = InitializedEntity::InitializeNew(StartLoc, InitType);
    InitializationSequence InitSeq(*this, Entity, Kind,
                                   MultiExprArg(Inits, NumInits));
    ExprResult FullInit = InitSeq.Perform(*this, Entity, Kind,
                                          MultiExprArg(Inits, NumInits));
    if (FullInit.isInvalid())
      return ExprError();
 
    // FullInit is our initializer; strip off CXXBindTemporaryExprs, because
    // we don't want the initialized object to be destructed.
    // FIXME: We should not create these in the first place.
    if (CXXBindTemporaryExpr *Binder =
            dyn_cast_or_null<CXXBindTemporaryExpr>(FullInit.get()))
      FullInit = Binder->getSubExpr();
 
    Initializer = FullInit.get();
 
    // FIXME: If we have a KnownArraySize, check that the array bound of the
    // initializer is no greater than that constant value.
 
    if (ArraySize && !*ArraySize) {
      auto *CAT = Context.getAsConstantArrayType(Initializer->getType());
      if (CAT) {
        // FIXME: Track that the array size was inferred rather than explicitly
        // specified.
        ArraySize = IntegerLiteral::Create(
            Context, CAT->getSize(), Context.getSizeType(), TypeRange.getEnd());
      } else {
        Diag(TypeRange.getEnd(), diag::err_new_array_size_unknown_from_init)
            << Initializer->getSourceRange();
      }
    }
  }
 
  // Mark the new and delete operators as referenced.
  if (OperatorNew) {
    if (DiagnoseUseOfDecl(OperatorNew, StartLoc))
      return ExprError();
    MarkFunctionReferenced(StartLoc, OperatorNew);
  }
  if (OperatorDelete) {
    if (DiagnoseUseOfDecl(OperatorDelete, StartLoc))
      return ExprError();
    MarkFunctionReferenced(StartLoc, OperatorDelete);
  }
 
  return CXXNewExpr::Create(Context, UseGlobal, OperatorNew, OperatorDelete,
                            PassAlignment, UsualArrayDeleteWantsSize,
                            PlacementArgs, TypeIdParens, ArraySize, initStyle,
                            Initializer, ResultType, AllocTypeInfo, Range,
                            DirectInitRange);
}
 
/// Checks that a type is suitable as the allocated type
/// in a new-expression.
bool Sema::CheckAllocatedType(QualType AllocType, SourceLocation Loc,
                              SourceRange R) {
  // C++ 5.3.4p1: "[The] type shall be a complete object type, but not an
  //   abstract class type or array thereof.
  if (AllocType->isFunctionType())
    return Diag(Loc, diag::err_bad_new_type)
      << AllocType << 0 << R;
  else if (AllocType->isReferenceType())
    return Diag(Loc, diag::err_bad_new_type)
      << AllocType << 1 << R;
  else if (!AllocType->isDependentType() &&
           RequireCompleteSizedType(
               Loc, AllocType, diag::err_new_incomplete_or_sizeless_type, R))
    return true;
  else if (RequireNonAbstractType(Loc, AllocType,
                                  diag::err_allocation_of_abstract_type))
    return true;
  else if (AllocType->isVariablyModifiedType())
    return Diag(Loc, diag::err_variably_modified_new_type)
             << AllocType;
  else if (AllocType.getAddressSpace() != LangAS::Default &&
           !getLangOpts().OpenCLCPlusPlus)
    return Diag(Loc, diag::err_address_space_qualified_new)
      << AllocType.getUnqualifiedType()
      << AllocType.getQualifiers().getAddressSpaceAttributePrintValue();
  else if (getLangOpts().ObjCAutoRefCount) {
    if (const ArrayType *AT = Context.getAsArrayType(AllocType)) {
      QualType BaseAllocType = Context.getBaseElementType(AT);
      if (BaseAllocType.getObjCLifetime() == Qualifiers::OCL_None &&
          BaseAllocType->isObjCLifetimeType())
        return Diag(Loc, diag::err_arc_new_array_without_ownership)
          << BaseAllocType;
    }
  }
 
  return false;
}
 
static bool resolveAllocationOverload(
    Sema &S, LookupResult &R, SourceRange Range, SmallVectorImpl<Expr *> &Args,
    bool &PassAlignment, FunctionDecl *&Operator,
    OverloadCandidateSet *AlignedCandidates, Expr *AlignArg, bool Diagnose) {
  OverloadCandidateSet Candidates(R.getNameLoc(),
                                  OverloadCandidateSet::CSK_Normal);
  for (LookupResult::iterator Alloc = R.begin(), AllocEnd = R.end();
       Alloc != AllocEnd; ++Alloc) {
    // Even member operator new/delete are implicitly treated as
    // static, so don't use AddMemberCandidate.
    NamedDecl *D = (*Alloc)->getUnderlyingDecl();
 
    if (FunctionTemplateDecl *FnTemplate = dyn_cast<FunctionTemplateDecl>(D)) {
      S.AddTemplateOverloadCandidate(FnTemplate, Alloc.getPair(),
                                     /*ExplicitTemplateArgs=*/nullptr, Args,
                                     Candidates,
                                     /*SuppressUserConversions=*/false);
      continue;
    }
 
    FunctionDecl *Fn = cast<FunctionDecl>(D);
    S.AddOverloadCandidate(Fn, Alloc.getPair(), Args, Candidates,
                           /*SuppressUserConversions=*/false);
  }
 
  // Do the resolution.
  OverloadCandidateSet::iterator Best;
  switch (Candidates.BestViableFunction(S, R.getNameLoc(), Best)) {
  case OR_Success: {
    // Got one!
    FunctionDecl *FnDecl = Best->Function;
    if (S.CheckAllocationAccess(R.getNameLoc(), Range, R.getNamingClass(),
                                Best->FoundDecl) == Sema::AR_inaccessible)
      return true;
 
    Operator = FnDecl;
    return false;
  }
 
  case OR_No_Viable_Function:
    // C++17 [expr.new]p13:
    //   If no matching function is found and the allocated object type has
    //   new-extended alignment, the alignment argument is removed from the
    //   argument list, and overload resolution is performed again.
    if (PassAlignment) {
      PassAlignment = false;
      AlignArg = Args[1];
      Args.erase(Args.begin() + 1);
      return resolveAllocationOverload(S, R, Range, Args, PassAlignment,
                                       Operator, &Candidates, AlignArg,
                                       Diagnose);
    }
 
    // MSVC will fall back on trying to find a matching global operator new
    // if operator new[] cannot be found.  Also, MSVC will leak by not
    // generating a call to operator delete or operator delete[], but we
    // will not replicate that bug.
    // FIXME: Find out how this interacts with the std::align_val_t fallback
    // once MSVC implements it.
    if (R.getLookupName().getCXXOverloadedOperator() == OO_Array_New &&
        S.Context.getLangOpts().MSVCCompat) {
      R.clear();
      R.setLookupName(S.Context.DeclarationNames.getCXXOperatorName(OO_New));
      S.LookupQualifiedName(R, S.Context.getTranslationUnitDecl());
      // FIXME: This will give bad diagnostics pointing at the wrong functions.
      return resolveAllocationOverload(S, R, Range, Args, PassAlignment,
                                       Operator, /*Candidates=*/nullptr,
                                       /*AlignArg=*/nullptr, Diagnose);
    }
 
    if (Diagnose) {
      // If this is an allocation of the form 'new (p) X' for some object
      // pointer p (or an expression that will decay to such a pointer),
      // diagnose the missing inclusion of <new>.
      if (!R.isClassLookup() && Args.size() == 2 &&
          (Args[1]->getType()->isObjectPointerType() ||
           Args[1]->getType()->isArrayType())) {
        S.Diag(R.getNameLoc(), diag::err_need_header_before_placement_new)
            << R.getLookupName() << Range;
        // Listing the candidates is unlikely to be useful; skip it.
        return true;
      }
 
      // Finish checking all candidates before we note any. This checking can
      // produce additional diagnostics so can't be interleaved with our
      // emission of notes.
      //
      // For an aligned allocation, separately check the aligned and unaligned
      // candidates with their respective argument lists.
      SmallVector<OverloadCandidate*, 32> Cands;
      SmallVector<OverloadCandidate*, 32> AlignedCands;
      llvm::SmallVector<Expr*, 4> AlignedArgs;
      if (AlignedCandidates) {
        auto IsAligned = [](OverloadCandidate &C) {
          return C.Function->getNumParams() > 1 &&
                 C.Function->getParamDecl(1)->getType()->isAlignValT();
        };
        auto IsUnaligned = [&](OverloadCandidate &C) { return !IsAligned(C); };
 
        AlignedArgs.reserve(Args.size() + 1);
        AlignedArgs.push_back(Args[0]);
        AlignedArgs.push_back(AlignArg);
        AlignedArgs.append(Args.begin() + 1, Args.end());
        AlignedCands = AlignedCandidates->CompleteCandidates(
            S, OCD_AllCandidates, AlignedArgs, R.getNameLoc(), IsAligned);
 
        Cands = Candidates.CompleteCandidates(S, OCD_AllCandidates, Args,
                                              R.getNameLoc(), IsUnaligned);
      } else {
        Cands = Candidates.CompleteCandidates(S, OCD_AllCandidates, Args,
                                              R.getNameLoc());
      }
 
      S.Diag(R.getNameLoc(), diag::err_ovl_no_viable_function_in_call)
          << R.getLookupName() << Range;
      if (AlignedCandidates)
        AlignedCandidates->NoteCandidates(S, AlignedArgs, AlignedCands, "",
                                          R.getNameLoc());
      Candidates.NoteCandidates(S, Args, Cands, "", R.getNameLoc());
    }
    return true;
 
  case OR_Ambiguous:
    if (Diagnose) {
      Candidates.NoteCandidates(
          PartialDiagnosticAt(R.getNameLoc(),
                              S.PDiag(diag::err_ovl_ambiguous_call)
                                  << R.getLookupName() << Range),
          S, OCD_AmbiguousCandidates, Args);
    }
    return true;
 
  case OR_Deleted: {
    if (Diagnose) {
      Candidates.NoteCandidates(
          PartialDiagnosticAt(R.getNameLoc(),
                              S.PDiag(diag::err_ovl_deleted_call)
                                  << R.getLookupName() << Range),
          S, OCD_AllCandidates, Args);
    }
    return true;
  }
  }
  llvm_unreachable("Unreachable, bad result from BestViableFunction");
}
 
bool Sema::FindAllocationFunctions(SourceLocation StartLoc, SourceRange Range,
                                   AllocationFunctionScope NewScope,
                                   AllocationFunctionScope DeleteScope,
                                   QualType AllocType, bool IsArray,
                                   bool &PassAlignment, MultiExprArg PlaceArgs,
                                   FunctionDecl *&OperatorNew,
                                   FunctionDecl *&OperatorDelete,
                                   bool Diagnose) {
  // --- Choosing an allocation function ---
  // C++ 5.3.4p8 - 14 & 18
  // 1) If looking in AFS_Global scope for allocation functions, only look in
  //    the global scope. Else, if AFS_Class, only look in the scope of the
  //    allocated class. If AFS_Both, look in both.
  // 2) If an array size is given, look for operator new[], else look for
  //   operator new.
  // 3) The first argument is always size_t. Append the arguments from the
  //   placement form.
 
  SmallVector<Expr*, 8> AllocArgs;
  AllocArgs.reserve((PassAlignment ? 2 : 1) + PlaceArgs.size());
 
  // We don't care about the actual value of these arguments.
  // FIXME: Should the Sema create the expression and embed it in the syntax
  // tree? Or should the consumer just recalculate the value?
  // FIXME: Using a dummy value will interact poorly with attribute enable_if.
  IntegerLiteral Size(
      Context, llvm::APInt::getZero(Context.getTargetInfo().getPointerWidth(0)),
      Context.getSizeType(), SourceLocation());
  AllocArgs.push_back(&Size);
 
  QualType AlignValT = Context.VoidTy;
  if (PassAlignment) {
    DeclareGlobalNewDelete();
    AlignValT = Context.getTypeDeclType(getStdAlignValT());
  }
  CXXScalarValueInitExpr Align(AlignValT, nullptr, SourceLocation());
  if (PassAlignment)
    AllocArgs.push_back(&Align);
 
  AllocArgs.insert(AllocArgs.end(), PlaceArgs.begin(), PlaceArgs.end());
 
  // C++ [expr.new]p8:
  //   If the allocated type is a non-array type, the allocation
  //   function's name is operator new and the deallocation function's
  //   name is operator delete. If the allocated type is an array
  //   type, the allocation function's name is operator new[] and the
  //   deallocation function's name is operator delete[].
  DeclarationName NewName = Context.DeclarationNames.getCXXOperatorName(
      IsArray ? OO_Array_New : OO_New);
 
  QualType AllocElemType = Context.getBaseElementType(AllocType);
 
  // Find the allocation function.
  {
    LookupResult R(*this, NewName, StartLoc, LookupOrdinaryName);
 
    // C++1z [expr.new]p9:
    //   If the new-expression begins with a unary :: operator, the allocation
    //   function's name is looked up in the global scope. Otherwise, if the
    //   allocated type is a class type T or array thereof, the allocation
    //   function's name is looked up in the scope of T.
    if (AllocElemType->isRecordType() && NewScope != AFS_Global)
      LookupQualifiedName(R, AllocElemType->getAsCXXRecordDecl());
 
    // We can see ambiguity here if the allocation function is found in
    // multiple base classes.
    if (R.isAmbiguous())
      return true;
 
    //   If this lookup fails to find the name, or if the allocated type is not
    //   a class type, the allocation function's name is looked up in the
    //   global scope.
    if (R.empty()) {
      if (NewScope == AFS_Class)
        return true;
 
      LookupQualifiedName(R, Context.getTranslationUnitDecl());
    }
 
    if (getLangOpts().OpenCLCPlusPlus && R.empty()) {
      if (PlaceArgs.empty()) {
        Diag(StartLoc, diag::err_openclcxx_not_supported) << "default new";
      } else {
        Diag(StartLoc, diag::err_openclcxx_placement_new);
      }
      return true;
    }
 
    assert(!R.empty() && "implicitly declared allocation functions not found");
    assert(!R.isAmbiguous() && "global allocation functions are ambiguous");
 
    // We do our own custom access checks below.
    R.suppressDiagnostics();
 
    if (resolveAllocationOverload(*this, R, Range, AllocArgs, PassAlignment,
                                  OperatorNew, /*Candidates=*/nullptr,
                                  /*AlignArg=*/nullptr, Diagnose))
      return true;
  }
 
  // We don't need an operator delete if we're running under -fno-exceptions.
  if (!getLangOpts().Exceptions) {
    OperatorDelete = nullptr;
    return false;
  }
 
  // Note, the name of OperatorNew might have been changed from array to
  // non-array by resolveAllocationOverload.
  DeclarationName DeleteName = Context.DeclarationNames.getCXXOperatorName(
      OperatorNew->getDeclName().getCXXOverloadedOperator() == OO_Array_New
          ? OO_Array_Delete
          : OO_Delete);
 
  // C++ [expr.new]p19:
  //
  //   If the new-expression begins with a unary :: operator, the
  //   deallocation function's name is looked up in the global
  //   scope. Otherwise, if the allocated type is a class type T or an
  //   array thereof, the deallocation function's name is looked up in
  //   the scope of T. If this lookup fails to find the name, or if
  //   the allocated type is not a class type or array thereof, the
  //   deallocation function's name is looked up in the global scope.
  LookupResult FoundDelete(*this, DeleteName, StartLoc, LookupOrdinaryName);
  if (AllocElemType->isRecordType() && DeleteScope != AFS_Global) {
    auto *RD =
        cast<CXXRecordDecl>(AllocElemType->castAs<RecordType>()->getDecl());
    LookupQualifiedName(FoundDelete, RD);
  }
  if (FoundDelete.isAmbiguous())
    return true; // FIXME: clean up expressions?
 
  // Filter out any destroying operator deletes. We can't possibly call such a
  // function in this context, because we're handling the case where the object
  // was not successfully constructed.
  // FIXME: This is not covered by the language rules yet.
  {
    LookupResult::Filter Filter = FoundDelete.makeFilter();
    while (Filter.hasNext()) {
      auto *FD = dyn_cast<FunctionDecl>(Filter.next()->getUnderlyingDecl());
      if (FD && FD->isDestroyingOperatorDelete())
        Filter.erase();
    }
    Filter.done();
  }
 
  bool FoundGlobalDelete = FoundDelete.empty();
  if (FoundDelete.empty()) {
    FoundDelete.clear(LookupOrdinaryName);
 
    if (DeleteScope == AFS_Class)
      return true;
 
    DeclareGlobalNewDelete();
    LookupQualifiedName(FoundDelete, Context.getTranslationUnitDecl());
  }
 
  FoundDelete.suppressDiagnostics();
 
  SmallVector<std::pair<DeclAccessPair,FunctionDecl*>, 2> Matches;
 
  // Whether we're looking for a placement operator delete is dictated
  // by whether we selected a placement operator new, not by whether
  // we had explicit placement arguments.  This matters for things like
  //   struct A { void *operator new(size_t, int = 0); ... };
  //   A *a = new A()
  //
  // We don't have any definition for what a "placement allocation function"
  // is, but we assume it's any allocation function whose
  // parameter-declaration-clause is anything other than (size_t).
  //
  // FIXME: Should (size_t, std::align_val_t) also be considered non-placement?
  // This affects whether an exception from the constructor of an overaligned
  // type uses the sized or non-sized form of aligned operator delete.
  bool isPlacementNew = !PlaceArgs.empty() || OperatorNew->param_size() != 1 ||
                        OperatorNew->isVariadic();
 
  if (isPlacementNew) {
    // C++ [expr.new]p20:
    //   A declaration of a placement deallocation function matches the
    //   declaration of a placement allocation function if it has the
    //   same number of parameters and, after parameter transformations
    //   (8.3.5), all parameter types except the first are
    //   identical. [...]
    //
    // To perform this comparison, we compute the function type that
    // the deallocation function should have, and use that type both
    // for template argument deduction and for comparison purposes.
    QualType ExpectedFunctionType;
    {
      auto *Proto = OperatorNew->getType()->castAs<FunctionProtoType>();
 
      SmallVector<QualType, 4> ArgTypes;
      ArgTypes.push_back(Context.VoidPtrTy);
      for (unsigned I = 1, N = Proto->getNumParams(); I < N; ++I)
        ArgTypes.push_back(Proto->getParamType(I));
 
      FunctionProtoType::ExtProtoInfo EPI;
      // FIXME: This is not part of the standard's rule.
      EPI.Variadic = Proto->isVariadic();
 
      ExpectedFunctionType
        = Context.getFunctionType(Context.VoidTy, ArgTypes, EPI);
    }
 
    for (LookupResult::iterator D = FoundDelete.begin(),
                             DEnd = FoundDelete.end();
         D != DEnd; ++D) {
      FunctionDecl *Fn = nullptr;
      if (FunctionTemplateDecl *FnTmpl =
              dyn_cast<FunctionTemplateDecl>((*D)->getUnderlyingDecl())) {
        // Perform template argument deduction to try to match the
        // expected function type.
        TemplateDeductionInfo Info(StartLoc);
        if (DeduceTemplateArguments(FnTmpl, nullptr, ExpectedFunctionType, Fn,
                                    Info))
          continue;
      } else
        Fn = cast<FunctionDecl>((*D)->getUnderlyingDecl());
 
      if (Context.hasSameType(adjustCCAndNoReturn(Fn->getType(),
                                                  ExpectedFunctionType,
                                                  /*AdjustExcpetionSpec*/true),
                              ExpectedFunctionType))
        Matches.push_back(std::make_pair(D.getPair(), Fn));
    }
 
    if (getLangOpts().CUDA)
      EraseUnwantedCUDAMatches(dyn_cast<FunctionDecl>(CurContext), Matches);
  } else {
    // C++1y [expr.new]p22:
    //   For a non-placement allocation function, the normal deallocation
    //   function lookup is used
    //
    // Per [expr.delete]p10, this lookup prefers a member operator delete
    // without a size_t argument, but prefers a non-member operator delete
    // with a size_t where possible (which it always is in this case).
    llvm::SmallVector<UsualDeallocFnInfo, 4> BestDeallocFns;
    UsualDeallocFnInfo Selected = resolveDeallocationOverload(
        *this, FoundDelete, /*WantSize*/ FoundGlobalDelete,
        /*WantAlign*/ hasNewExtendedAlignment(*this, AllocElemType),
        &BestDeallocFns);
    if (Selected)
      Matches.push_back(std::make_pair(Selected.Found, Selected.FD));
    else {
      // If we failed to select an operator, all remaining functions are viable
      // but ambiguous.
      for (auto Fn : BestDeallocFns)
        Matches.push_back(std::make_pair(Fn.Found, Fn.FD));
    }
  }
 
  // C++ [expr.new]p20:
  //   [...] If the lookup finds a single matching deallocation
  //   function, that function will be called; otherwise, no
  //   deallocation function will be called.
  if (Matches.size() == 1) {
    OperatorDelete = Matches[0].second;
 
    // C++1z [expr.new]p23:
    //   If the lookup finds a usual deallocation function (3.7.4.2)
    //   with a parameter of type std::size_t and that function, considered
    //   as a placement deallocation function, would have been
    //   selected as a match for the allocation function, the program
    //   is ill-formed.
    if (getLangOpts().CPlusPlus11 && isPlacementNew &&
        isNonPlacementDeallocationFunction(*this, OperatorDelete)) {
      UsualDeallocFnInfo Info(*this,
                              DeclAccessPair::make(OperatorDelete, AS_public));
      // Core issue, per mail to core reflector, 2016-10-09:
      //   If this is a member operator delete, and there is a corresponding
      //   non-sized member operator delete, this isn't /really/ a sized
      //   deallocation function, it just happens to have a size_t parameter.
      bool IsSizedDelete = Info.HasSizeT;
      if (IsSizedDelete && !FoundGlobalDelete) {
        auto NonSizedDelete =
            resolveDeallocationOverload(*this, FoundDelete, /*WantSize*/false,
                                        /*WantAlign*/Info.HasAlignValT);
        if (NonSizedDelete && !NonSizedDelete.HasSizeT &&
            NonSizedDelete.HasAlignValT == Info.HasAlignValT)
          IsSizedDelete = false;
      }
 
      if (IsSizedDelete) {
        SourceRange R = PlaceArgs.empty()
                            ? SourceRange()
                            : SourceRange(PlaceArgs.front()->getBeginLoc(),
                                          PlaceArgs.back()->getEndLoc());
        Diag(StartLoc, diag::err_placement_new_non_placement_delete) << R;
        if (!OperatorDelete->isImplicit())
          Diag(OperatorDelete->getLocation(), diag::note_previous_decl)
              << DeleteName;
      }
    }
 
    CheckAllocationAccess(StartLoc, Range, FoundDelete.getNamingClass(),
                          Matches[0].first);
  } else if (!Matches.empty()) {
    // We found multiple suitable operators. Per [expr.new]p20, that means we
    // call no 'operator delete' function, but we should at least warn the user.
    // FIXME: Suppress this warning if the construction cannot throw.
    Diag(StartLoc, diag::warn_ambiguous_suitable_delete_function_found)
      << DeleteName << AllocElemType;
 
    for (auto &Match : Matches)
      Diag(Match.second->getLocation(),
           diag::note_member_declared_here) << DeleteName;
  }
 
  return false;
}
 
/// DeclareGlobalNewDelete - Declare the global forms of operator new and
/// delete. These are:
/// @code
///   // C++03:
///   void* operator new(std::size_t) throw(std::bad_alloc);
///   void* operator new[](std::size_t) throw(std::bad_alloc);
///   void operator delete(void *) throw();
///   void operator delete[](void *) throw();
///   // C++11:
///   void* operator new(std::size_t);
///   void* operator new[](std::size_t);
///   void operator delete(void *) noexcept;
///   void operator delete[](void *) noexcept;
///   // C++1y:
///   void* operator new(std::size_t);
///   void* operator new[](std::size_t);
///   void operator delete(void *) noexcept;
///   void operator delete[](void *) noexcept;
///   void operator delete(void *, std::size_t) noexcept;
///   void operator delete[](void *, std::size_t) noexcept;
/// @endcode
/// Note that the placement and nothrow forms of new are *not* implicitly
/// declared. Their use requires including <new>.
void Sema::DeclareGlobalNewDelete() {
  if (GlobalNewDeleteDeclared)
    return;
 
  // The implicitly declared new and delete operators
  // are not supported in OpenCL.
  if (getLangOpts().OpenCLCPlusPlus)
    return;
 
  // C++ [basic.std.dynamic]p2:
  //   [...] The following allocation and deallocation functions (18.4) are
  //   implicitly declared in global scope in each translation unit of a
  //   program
  //
  //     C++03:
  //     void* operator new(std::size_t) throw(std::bad_alloc);
  //     void* operator new[](std::size_t) throw(std::bad_alloc);
  //     void  operator delete(void*) throw();
  //     void  operator delete[](void*) throw();
  //     C++11:
  //     void* operator new(std::size_t);
  //     void* operator new[](std::size_t);
  //     void  operator delete(void*) noexcept;
  //     void  operator delete[](void*) noexcept;
  //     C++1y:
  //     void* operator new(std::size_t);
  //     void* operator new[](std::size_t);
  //     void  operator delete(void*) noexcept;
  //     void  operator delete[](void*) noexcept;
  //     void  operator delete(void*, std::size_t) noexcept;
  //     void  operator delete[](void*, std::size_t) noexcept;
  //
  //   These implicit declarations introduce only the function names operator
  //   new, operator new[], operator delete, operator delete[].
  //
  // Here, we need to refer to std::bad_alloc, so we will implicitly declare
  // "std" or "bad_alloc" as necessary to form the exception specification.
  // However, we do not make these implicit declarations visible to name
  // lookup.
  if (!StdBadAlloc && !getLangOpts().CPlusPlus11) {
    // The "std::bad_alloc" class has not yet been declared, so build it
    // implicitly.
    StdBadAlloc = CXXRecordDecl::Create(Context, TTK_Class,
                                        getOrCreateStdNamespace(),
                                        SourceLocation(), SourceLocation(),
                                      &PP.getIdentifierTable().get("bad_alloc"),
                                        nullptr);
    getStdBadAlloc()->setImplicit(true);
  }
  if (!StdAlignValT && getLangOpts().AlignedAllocation) {
    // The "std::align_val_t" enum class has not yet been declared, so build it
    // implicitly.
    auto *AlignValT = EnumDecl::Create(
        Context, getOrCreateStdNamespace(), SourceLocation(), SourceLocation(),
        &PP.getIdentifierTable().get("align_val_t"), nullptr, true, true, true);
    AlignValT->setIntegerType(Context.getSizeType());
    AlignValT->setPromotionType(Context.getSizeType());
    AlignValT->setImplicit(true);
    StdAlignValT = AlignValT;
  }
 
  GlobalNewDeleteDeclared = true;
 
  QualType VoidPtr = Context.getPointerType(Context.VoidTy);
  QualType SizeT = Context.getSizeType();
 
  auto DeclareGlobalAllocationFunctions = [&](OverloadedOperatorKind Kind,
                                              QualType Return, QualType Param) {
    llvm::SmallVector<QualType, 3> Params;
    Params.push_back(Param);
 
    // Create up to four variants of the function (sized/aligned).
    bool HasSizedVariant = getLangOpts().SizedDeallocation &&
                           (Kind == OO_Delete || Kind == OO_Array_Delete);
    bool HasAlignedVariant = getLangOpts().AlignedAllocation;
 
    int NumSizeVariants = (HasSizedVariant ? 2 : 1);
    int NumAlignVariants = (HasAlignedVariant ? 2 : 1);
    for (int Sized = 0; Sized < NumSizeVariants; ++Sized) {
      if (Sized)
        Params.push_back(SizeT);
 
      for (int Aligned = 0; Aligned < NumAlignVariants; ++Aligned) {
        if (Aligned)
          Params.push_back(Context.getTypeDeclType(getStdAlignValT()));
 
        DeclareGlobalAllocationFunction(
            Context.DeclarationNames.getCXXOperatorName(Kind), Return, Params);
 
        if (Aligned)
          Params.pop_back();
      }
    }
  };
 
  DeclareGlobalAllocationFunctions(OO_New, VoidPtr, SizeT);
  DeclareGlobalAllocationFunctions(OO_Array_New, VoidPtr, SizeT);
  DeclareGlobalAllocationFunctions(OO_Delete, Context.VoidTy, VoidPtr);
  DeclareGlobalAllocationFunctions(OO_Array_Delete, Context.VoidTy, VoidPtr);
}
 
/// DeclareGlobalAllocationFunction - Declares a single implicit global
/// allocation function if it doesn't already exist.
void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
                                           QualType Return,
                                           ArrayRef<QualType> Params) {
  DeclContext *GlobalCtx = Context.getTranslationUnitDecl();
 
  // Check if this function is already declared.
  DeclContext::lookup_result R = GlobalCtx->lookup(Name);
  for (DeclContext::lookup_iterator Alloc = R.begin(), AllocEnd = R.end();
       Alloc != AllocEnd; ++Alloc) {
    // Only look at non-template functions, as it is the predefined,
    // non-templated allocation function we are trying to declare here.
    if (FunctionDecl *Func = dyn_cast<FunctionDecl>(*Alloc)) {
      if (Func->getNumParams() == Params.size()) {
        llvm::SmallVector<QualType, 3> FuncParams;
        for (auto *P : Func->parameters())
          FuncParams.push_back(
              Context.getCanonicalType(P->getType().getUnqualifiedType()));
        if (llvm::makeArrayRef(FuncParams) == Params) {
          // Make the function visible to name lookup, even if we found it in
          // an unimported module. It either is an implicitly-declared global
          // allocation function, or is suppressing that function.
          Func->setVisibleDespiteOwningModule();
          return;
        }
      }
    }
  }
 
  FunctionProtoType::ExtProtoInfo EPI(Context.getDefaultCallingConvention(
      /*IsVariadic=*/false, /*IsCXXMethod=*/false, /*IsBuiltin=*/true));
 
  QualType BadAllocType;
  bool HasBadAllocExceptionSpec
    = (Name.getCXXOverloadedOperator() == OO_New ||
       Name.getCXXOverloadedOperator() == OO_Array_New);
  if (HasBadAllocExceptionSpec) {
    if (!getLangOpts().CPlusPlus11) {
      BadAllocType = Context.getTypeDeclType(getStdBadAlloc());
      assert(StdBadAlloc && "Must have std::bad_alloc declared");
      EPI.ExceptionSpec.Type = EST_Dynamic;
      EPI.ExceptionSpec.Exceptions = llvm::makeArrayRef(BadAllocType);
    }
    if (getLangOpts().NewInfallible) {
      EPI.ExceptionSpec.Type = EST_DynamicNone;
    }
  } else {
    EPI.ExceptionSpec =
        getLangOpts().CPlusPlus11 ? EST_BasicNoexcept : EST_DynamicNone;
  }
 
  auto CreateAllocationFunctionDecl = [&](Attr *ExtraAttr) {
    QualType FnType = Context.getFunctionType(Return, Params, EPI);
    FunctionDecl *Alloc = FunctionDecl::Create(
        Context, GlobalCtx, SourceLocation(), SourceLocation(), Name, FnType,
        /*TInfo=*/nullptr, SC_None, getCurFPFeatures().isFPConstrained(), false,
        true);
    Alloc->setImplicit();
    // Global allocation functions should always be visible.
    Alloc->setVisibleDespiteOwningModule();
 
    if (HasBadAllocExceptionSpec && getLangOpts().NewInfallible)
      Alloc->addAttr(
          ReturnsNonNullAttr::CreateImplicit(Context, Alloc->getLocation()));
 
    Alloc->addAttr(VisibilityAttr::CreateImplicit(
        Context, LangOpts.GlobalAllocationFunctionVisibilityHidden
                     ? VisibilityAttr::Hidden
                     : VisibilityAttr::Default));
 
    llvm::SmallVector<ParmVarDecl *, 3> ParamDecls;
    for (QualType T : Params) {
      ParamDecls.push_back(ParmVarDecl::Create(
          Context, Alloc, SourceLocation(), SourceLocation(), nullptr, T,
          /*TInfo=*/nullptr, SC_None, nullptr));
      ParamDecls.back()->setImplicit();
    }
    Alloc->setParams(ParamDecls);
    if (ExtraAttr)
      Alloc->addAttr(ExtraAttr);
    AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(Alloc);
    Context.getTranslationUnitDecl()->addDecl(Alloc);
    IdResolver.tryAddTopLevelDecl(Alloc, Name);
  };
 
  if (!LangOpts.CUDA)
    CreateAllocationFunctionDecl(nullptr);
  else {
    // Host and device get their own declaration so each can be
    // defined or re-declared independently.
    CreateAllocationFunctionDecl(CUDAHostAttr::CreateImplicit(Context));
    CreateAllocationFunctionDecl(CUDADeviceAttr::CreateImplicit(Context));
  }
}
 
FunctionDecl *Sema::FindUsualDeallocationFunction(SourceLocation StartLoc,
                                                  bool CanProvideSize,
                                                  bool Overaligned,
                                                  DeclarationName Name) {
  DeclareGlobalNewDelete();
 
  LookupResult FoundDelete(*this, Name, StartLoc, LookupOrdinaryName);
  LookupQualifiedName(FoundDelete, Context.getTranslationUnitDecl());
 
  // FIXME: It's possible for this to result in ambiguity, through a
  // user-declared variadic operator delete or the enable_if attribute. We
  // should probably not consider those cases to be usual deallocation
  // functions. But for now we just make an arbitrary choice in that case.
  auto Result = resolveDeallocationOverload(*this, FoundDelete, CanProvideSize,
                                            Overaligned);
  assert(Result.FD && "operator delete missing from global scope?");
  return Result.FD;
}
 
FunctionDecl *Sema::FindDeallocationFunctionForDestructor(SourceLocation Loc,
                                                          CXXRecordDecl *RD) {
  DeclarationName Name = Context.DeclarationNames.getCXXOperatorName(OO_Delete);
 
  FunctionDecl *OperatorDelete = nullptr;
  if (FindDeallocationFunction(Loc, RD, Name, OperatorDelete))
    return nullptr;
  if (OperatorDelete)
    return OperatorDelete;
 
  // If there's no class-specific operator delete, look up the global
  // non-array delete.
  return FindUsualDeallocationFunction(
      Loc, true, hasNewExtendedAlignment(*this, Context.getRecordType(RD)),
      Name);
}
 
bool Sema::FindDeallocationFunction(SourceLocation StartLoc, CXXRecordDecl *RD,
                                    DeclarationName Name,
                                    FunctionDecl *&Operator, bool Diagnose) {
  LookupResult Found(*this, Name, StartLoc, LookupOrdinaryName);
  // Try to find operator delete/operator delete[] in class scope.
  LookupQualifiedName(Found, RD);
 
  if (Found.isAmbiguous())
    return true;
 
  Found.suppressDiagnostics();
 
  bool Overaligned = hasNewExtendedAlignment(*this, Context.getRecordType(RD));
 
  // C++17 [expr.delete]p10:
  //   If the deallocation functions have class scope, the one without a
  //   parameter of type std::size_t is selected.
  llvm::SmallVector<UsualDeallocFnInfo, 4> Matches;
  resolveDeallocationOverload(*this, Found, /*WantSize*/ false,
                              /*WantAlign*/ Overaligned, &Matches);
 
  // If we could find an overload, use it.
  if (Matches.size() == 1) {
    Operator = cast<CXXMethodDecl>(Matches[0].FD);
 
    // FIXME: DiagnoseUseOfDecl?
    if (Operator->isDeleted()) {
      if (Diagnose) {
        Diag(StartLoc, diag::err_deleted_function_use);
        NoteDeletedFunction(Operator);
      }
      return true;
    }
 
    if (CheckAllocationAccess(StartLoc, SourceRange(), Found.getNamingClass(),
                              Matches[0].Found, Diagnose) == AR_inaccessible)
      return true;
 
    return false;
  }
 
  // We found multiple suitable operators; complain about the ambiguity.
  // FIXME: The standard doesn't say to do this; it appears that the intent
  // is that this should never happen.
  if (!Matches.empty()) {
    if (Diagnose) {
      Diag(StartLoc, diag::err_ambiguous_suitable_delete_member_function_found)
        << Name << RD;
      for (auto &Match : Matches)
        Diag(Match.FD->getLocation(), diag::note_member_declared_here) << Name;
    }
    return true;
  }
 
  // We did find operator delete/operator delete[] declarations, but
  // none of them were suitable.
  if (!Found.empty()) {
    if (Diagnose) {
      Diag(StartLoc, diag::err_no_suitable_delete_member_function_found)
        << Name << RD;
 
      for (NamedDecl *D : Found)
        Diag(D->getUnderlyingDecl()->getLocation(),
             diag::note_member_declared_here) << Name;
    }
    return true;
  }
 
  Operator = nullptr;
  return false;
}
 
namespace {
/// Checks whether delete-expression, and new-expression used for
///  initializing deletee have the same array form.
class MismatchingNewDeleteDetector {
public:
  enum MismatchResult {
    /// Indicates that there is no mismatch or a mismatch cannot be proven.
    NoMismatch,
    /// Indicates that variable is initialized with mismatching form of \a new.
    VarInitMismatches,
    /// Indicates that member is initialized with mismatching form of \a new.
    MemberInitMismatches,
    /// Indicates that 1 or more constructors' definitions could not been
    /// analyzed, and they will be checked again at the end of translation unit.
    AnalyzeLater
  };
 
  /// \param EndOfTU True, if this is the final analysis at the end of
  /// translation unit. False, if this is the initial analysis at the point
  /// delete-expression was encountered.
  explicit MismatchingNewDeleteDetector(bool EndOfTU)
      : Field(nullptr), IsArrayForm(false), EndOfTU(EndOfTU),
        HasUndefinedConstructors(false) {}
 
  /// Checks whether pointee of a delete-expression is initialized with
  /// matching form of new-expression.
  ///
  /// If return value is \c VarInitMismatches or \c MemberInitMismatches at the
  /// point where delete-expression is encountered, then a warning will be
  /// issued immediately. If return value is \c AnalyzeLater at the point where
  /// delete-expression is seen, then member will be analyzed at the end of
  /// translation unit. \c AnalyzeLater is returned iff at least one constructor
  /// couldn't be analyzed. If at least one constructor initializes the member
  /// with matching type of new, the return value is \c NoMismatch.
  MismatchResult analyzeDeleteExpr(const CXXDeleteExpr *DE);
  /// Analyzes a class member.
  /// \param Field Class member to analyze.
  /// \param DeleteWasArrayForm Array form-ness of the delete-expression used
  /// for deleting the \p Field.
  MismatchResult analyzeField(FieldDecl *Field, bool DeleteWasArrayForm);
  FieldDecl *Field;
  /// List of mismatching new-expressions used for initialization of the pointee
  llvm::SmallVector<const CXXNewExpr *, 4> NewExprs;
  /// Indicates whether delete-expression was in array form.
  bool IsArrayForm;
 
private:
  const bool EndOfTU;
  /// Indicates that there is at least one constructor without body.
  bool HasUndefinedConstructors;
  /// Returns \c CXXNewExpr from given initialization expression.
  /// \param E Expression used for initializing pointee in delete-expression.
  /// E can be a single-element \c InitListExpr consisting of new-expression.
  const CXXNewExpr *getNewExprFromInitListOrExpr(const Expr *E);
  /// Returns whether member is initialized with mismatching form of
  /// \c new either by the member initializer or in-class initialization.
  ///
  /// If bodies of all constructors are not visible at the end of translation
  /// unit or at least one constructor initializes member with the matching
  /// form of \c new, mismatch cannot be proven, and this function will return
  /// \c NoMismatch.
  MismatchResult analyzeMemberExpr(const MemberExpr *ME);
  /// Returns whether variable is initialized with mismatching form of
  /// \c new.
  ///
  /// If variable is initialized with matching form of \c new or variable is not
  /// initialized with a \c new expression, this function will return true.
  /// If variable is initialized with mismatching form of \c new, returns false.
  /// \param D Variable to analyze.
  bool hasMatchingVarInit(const DeclRefExpr *D);
  /// Checks whether the constructor initializes pointee with mismatching
  /// form of \c new.
  ///
  /// Returns true, if member is initialized with matching form of \c new in
  /// member initializer list. Returns false, if member is initialized with the
  /// matching form of \c new in this constructor's initializer or given
  /// constructor isn't defined at the point where delete-expression is seen, or
  /// member isn't initialized by the constructor.
  bool hasMatchingNewInCtor(const CXXConstructorDecl *CD);
  /// Checks whether member is initialized with matching form of
  /// \c new in member initializer list.
  bool hasMatchingNewInCtorInit(const CXXCtorInitializer *CI);
  /// Checks whether member is initialized with mismatching form of \c new by
  /// in-class initializer.
  MismatchResult analyzeInClassInitializer();
};
}
 
MismatchingNewDeleteDetector::MismatchResult
MismatchingNewDeleteDetector::analyzeDeleteExpr(const CXXDeleteExpr *DE) {
  NewExprs.clear();
  assert(DE && "Expected delete-expression");
  IsArrayForm = DE->isArrayForm();
  const Expr *E = DE->getArgument()->IgnoreParenImpCasts();
  if (const MemberExpr *ME = dyn_cast<const MemberExpr>(E)) {
    return analyzeMemberExpr(ME);
  } else if (const DeclRefExpr *D = dyn_cast<const DeclRefExpr>(E)) {
    if (!hasMatchingVarInit(D))
      return VarInitMismatches;
  }
  return NoMismatch;
}
 
const CXXNewExpr *
MismatchingNewDeleteDetector::getNewExprFromInitListOrExpr(const Expr *E) {
  assert(E != nullptr && "Expected a valid initializer expression");
  E = E->IgnoreParenImpCasts();
  if (const InitListExpr *ILE = dyn_cast<const InitListExpr>(E)) {
    if (ILE->getNumInits() == 1)
      E = dyn_cast<const CXXNewExpr>(ILE->getInit(0)->IgnoreParenImpCasts());
  }
 
  return dyn_cast_or_null<const CXXNewExpr>(E);
}
 
bool MismatchingNewDeleteDetector::hasMatchingNewInCtorInit(
    const CXXCtorInitializer *CI) {
  const CXXNewExpr *NE = nullptr;
  if (Field == CI->getMember() &&
      (NE = getNewExprFromInitListOrExpr(CI->getInit()))) {
    if (NE->isArray() == IsArrayForm)
      return true;
    else
      NewExprs.push_back(NE);
  }
  return false;
}
 
bool MismatchingNewDeleteDetector::hasMatchingNewInCtor(
    const CXXConstructorDecl *CD) {
  if (CD->isImplicit())
    return false;
  const FunctionDecl *Definition = CD;
  if (!CD->isThisDeclarationADefinition() && !CD->isDefined(Definition)) {
    HasUndefinedConstructors = true;
    return EndOfTU;
  }
  for (const auto *CI : cast<const CXXConstructorDecl>(Definition)->inits()) {
    if (hasMatchingNewInCtorInit(CI))
      return true;
  }
  return false;
}
 
MismatchingNewDeleteDetector::MismatchResult
MismatchingNewDeleteDetector::analyzeInClassInitializer() {
  assert(Field != nullptr && "This should be called only for members");
  const Expr *InitExpr = Field->getInClassInitializer();
  if (!InitExpr)
    return EndOfTU ? NoMismatch : AnalyzeLater;
  if (const CXXNewExpr *NE = getNewExprFromInitListOrExpr(InitExpr)) {
    if (NE->isArray() != IsArrayForm) {
      NewExprs.push_back(NE);
      return MemberInitMismatches;
    }
  }
  return NoMismatch;
}
 
MismatchingNewDeleteDetector::MismatchResult
MismatchingNewDeleteDetector::analyzeField(FieldDecl *Field,
                                           bool DeleteWasArrayForm) {
  assert(Field != nullptr && "Analysis requires a valid class member.");
  this->Field = Field;
  IsArrayForm = DeleteWasArrayForm;
  const CXXRecordDecl *RD = cast<const CXXRecordDecl>(Field->getParent());
  for (const auto *CD : RD->ctors()) {
    if (hasMatchingNewInCtor(CD))
      return NoMismatch;
  }
  if (HasUndefinedConstructors)
    return EndOfTU ? NoMismatch : AnalyzeLater;
  if (!NewExprs.empty())
    return MemberInitMismatches;
  return Field->hasInClassInitializer() ? analyzeInClassInitializer()
                                        : NoMismatch;
}
 
MismatchingNewDeleteDetector::MismatchResult
MismatchingNewDeleteDetector::analyzeMemberExpr(const MemberExpr *ME) {
  assert(ME != nullptr && "Expected a member expression");
  if (FieldDecl *F = dyn_cast<FieldDecl>(ME->getMemberDecl()))
    return analyzeField(F, IsArrayForm);
  return NoMismatch;
}
 
bool MismatchingNewDeleteDetector::hasMatchingVarInit(const DeclRefExpr *D) {
  const CXXNewExpr *NE = nullptr;
  if (const VarDecl *VD = dyn_cast<const VarDecl>(D->getDecl())) {
    if (VD->hasInit() && (NE = getNewExprFromInitListOrExpr(VD->getInit())) &&
        NE->isArray() != IsArrayForm) {
      NewExprs.push_back(NE);
    }
  }
  return NewExprs.empty();
}
 
static void
DiagnoseMismatchedNewDelete(Sema &SemaRef, SourceLocation DeleteLoc,
                            const MismatchingNewDeleteDetector &Detector) {
  SourceLocation EndOfDelete = SemaRef.getLocForEndOfToken(DeleteLoc);
  FixItHint H;
  if (!Detector.IsArrayForm)
    H = FixItHint::CreateInsertion(EndOfDelete, "[]");
  else {
    SourceLocation RSquare = Lexer::findLocationAfterToken(
        DeleteLoc, tok::l_square, SemaRef.getSourceManager(),
        SemaRef.getLangOpts(), true);
    if (RSquare.isValid())
      H = FixItHint::CreateRemoval(SourceRange(EndOfDelete, RSquare));
  }
  SemaRef.Diag(DeleteLoc, diag::warn_mismatched_delete_new)
      << Detector.IsArrayForm << H;
 
  for (const auto *NE : Detector.NewExprs)
    SemaRef.Diag(NE->getExprLoc(), diag::note_allocated_here)
        << Detector.IsArrayForm;
}
 
void Sema::AnalyzeDeleteExprMismatch(const CXXDeleteExpr *DE) {
  if (Diags.isIgnored(diag::warn_mismatched_delete_new, SourceLocation()))
    return;
  MismatchingNewDeleteDetector Detector(/*EndOfTU=*/false);
  switch (Detector.analyzeDeleteExpr(DE)) {
  case MismatchingNewDeleteDetector::VarInitMismatches:
  case MismatchingNewDeleteDetector::MemberInitMismatches: {
    DiagnoseMismatchedNewDelete(*this, DE->getBeginLoc(), Detector);
    break;
  }
  case MismatchingNewDeleteDetector::AnalyzeLater: {
    DeleteExprs[Detector.Field].push_back(
        std::make_pair(DE->getBeginLoc(), DE->isArrayForm()));
    break;
  }
  case MismatchingNewDeleteDetector::NoMismatch:
    break;
  }
}
 
void Sema::AnalyzeDeleteExprMismatch(FieldDecl *Field, SourceLocation DeleteLoc,
                                     bool DeleteWasArrayForm) {
  MismatchingNewDeleteDetector Detector(/*EndOfTU=*/true);
  switch (Detector.analyzeField(Field, DeleteWasArrayForm)) {
  case MismatchingNewDeleteDetector::VarInitMismatches:
    llvm_unreachable("This analysis should have been done for class members.");
  case MismatchingNewDeleteDetector::AnalyzeLater:
    llvm_unreachable("Analysis cannot be postponed any point beyond end of "
                     "translation unit.");
  case MismatchingNewDeleteDetector::MemberInitMismatches:
    DiagnoseMismatchedNewDelete(*this, DeleteLoc, Detector);
    break;
  case MismatchingNewDeleteDetector::NoMismatch:
    break;
  }
}
 
/// ActOnCXXDelete - Parsed a C++ 'delete' expression (C++ 5.3.5), as in:
/// @code ::delete ptr; @endcode
/// or
/// @code delete [] ptr; @endcode
ExprResult
Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
                     bool ArrayForm, Expr *ExE) {
  // C++ [expr.delete]p1:
  //   The operand shall have a pointer type, or a class type having a single
  //   non-explicit conversion function to a pointer type. The result has type
  //   void.
  //
  // DR599 amends "pointer type" to "pointer to object type" in both cases.
 
  ExprResult Ex = ExE;
  FunctionDecl *OperatorDelete = nullptr;
  bool ArrayFormAsWritten = ArrayForm;
  bool UsualArrayDeleteWantsSize = false;
 
  if (!Ex.get()->isTypeDependent()) {
    // Perform lvalue-to-rvalue cast, if needed.
    Ex = DefaultLvalueConversion(Ex.get());
    if (Ex.isInvalid())
      return ExprError();
 
    QualType Type = Ex.get()->getType();
 
    class DeleteConverter : public ContextualImplicitConverter {
    public:
      DeleteConverter() : ContextualImplicitConverter(false, true) {}
 
      bool match(QualType ConvType) override {
        // FIXME: If we have an operator T* and an operator void*, we must pick
        // the operator T*.
        if (const PointerType *ConvPtrType = ConvType->getAs<PointerType>())
          if (ConvPtrType->getPointeeType()->isIncompleteOrObjectType())
            return true;
        return false;
      }
 
      SemaDiagnosticBuilder diagnoseNoMatch(Sema &S, SourceLocation Loc,
                                            QualType T) override {
        return S.Diag(Loc, diag::err_delete_operand) << T;
      }
 
      SemaDiagnosticBuilder diagnoseIncomplete(Sema &S, SourceLocation Loc,
                                               QualType T) override {
        return S.Diag(Loc, diag::err_delete_incomplete_class_type) << T;
      }
 
      SemaDiagnosticBuilder diagnoseExplicitConv(Sema &S, SourceLocation Loc,
                                                 QualType T,
                                                 QualType ConvTy) override {
        return S.Diag(Loc, diag::err_delete_explicit_conversion) << T << ConvTy;
      }
 
      SemaDiagnosticBuilder noteExplicitConv(Sema &S, CXXConversionDecl *Conv,
                                             QualType ConvTy) override {
        return S.Diag(Conv->getLocation(), diag::note_delete_conversion)
          << ConvTy;
      }
 
      SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
                                              QualType T) override {
        return S.Diag(Loc, diag::err_ambiguous_delete_operand) << T;
      }
 
      SemaDiagnosticBuilder noteAmbiguous(Sema &S, CXXConversionDecl *Conv,
                                          QualType ConvTy) override {
        return S.Diag(Conv->getLocation(), diag::note_delete_conversion)
          << ConvTy;
      }
 
      SemaDiagnosticBuilder diagnoseConversion(Sema &S, SourceLocation Loc,
                                               QualType T,
                                               QualType ConvTy) override {
        llvm_unreachable("conversion functions are permitted");
      }
    } Converter;
 
    Ex = PerformContextualImplicitConversion(StartLoc, Ex.get(), Converter);
    if (Ex.isInvalid())
      return ExprError();
    Type = Ex.get()->getType();
    if (!Converter.match(Type))
      // FIXME: PerformContextualImplicitConversion should return ExprError
      //        itself in this case.
      return ExprError();
 
    QualType Pointee = Type->castAs<PointerType>()->getPointeeType();
    QualType PointeeElem = Context.getBaseElementType(Pointee);
 
    if (Pointee.getAddressSpace() != LangAS::Default &&
        !getLangOpts().OpenCLCPlusPlus)
      return Diag(Ex.get()->getBeginLoc(),
                  diag::err_address_space_qualified_delete)
             << Pointee.getUnqualifiedType()
             << Pointee.getQualifiers().getAddressSpaceAttributePrintValue();
 
    CXXRecordDecl *PointeeRD = nullptr;
    if (Pointee->isVoidType() && !isSFINAEContext()) {
      // The C++ standard bans deleting a pointer to a non-object type, which
      // effectively bans deletion of "void*". However, most compilers support
      // this, so we treat it as a warning unless we're in a SFINAE context.
      Diag(StartLoc, diag::ext_delete_void_ptr_operand)
        << Type << Ex.get()->getSourceRange();
    } else if (Pointee->isFunctionType() || Pointee->isVoidType() ||
               Pointee->isSizelessType()) {
      return ExprError(Diag(StartLoc, diag::err_delete_operand)
        << Type << Ex.get()->getSourceRange());
    } else if (!Pointee->isDependentType()) {
      // FIXME: This can result in errors if the definition was imported from a
      // module but is hidden.
      if (!RequireCompleteType(StartLoc, Pointee,
                               diag::warn_delete_incomplete, Ex.get())) {
        if (const RecordType *RT = PointeeElem->getAs<RecordType>())
          PointeeRD = cast<CXXRecordDecl>(RT->getDecl());
      }
    }
 
    if (Pointee->isArrayType() && !ArrayForm) {
      Diag(StartLoc, diag::warn_delete_array_type)
          << Type << Ex.get()->getSourceRange()
          << FixItHint::CreateInsertion(getLocForEndOfToken(StartLoc), "[]");
      ArrayForm = true;
    }
 
    DeclarationName DeleteName = Context.DeclarationNames.getCXXOperatorName(
                                      ArrayForm ? OO_Array_Delete : OO_Delete);
 
    if (PointeeRD) {
      if (!UseGlobal &&
          FindDeallocationFunction(StartLoc, PointeeRD, DeleteName,
                                   OperatorDelete))
        return ExprError();
 
      // If we're allocating an array of records, check whether the
      // usual operator delete[] has a size_t parameter.
      if (ArrayForm) {
        // If the user specifically asked to use the global allocator,
        // we'll need to do the lookup into the class.
        if (UseGlobal)
          UsualArrayDeleteWantsSize =
            doesUsualArrayDeleteWantSize(*this, StartLoc, PointeeElem);
 
        // Otherwise, the usual operator delete[] should be the
        // function we just found.
        else if (OperatorDelete && isa<CXXMethodDecl>(OperatorDelete))
          UsualArrayDeleteWantsSize =
            UsualDeallocFnInfo(*this,
                               DeclAccessPair::make(OperatorDelete, AS_public))
              .HasSizeT;
      }
 
      if (!PointeeRD->hasIrrelevantDestructor())
        if (CXXDestructorDecl *Dtor = LookupDestructor(PointeeRD)) {
          MarkFunctionReferenced(StartLoc,
                                    const_cast<CXXDestructorDecl*>(Dtor));
          if (DiagnoseUseOfDecl(Dtor, StartLoc))
            return ExprError();
        }
 
      CheckVirtualDtorCall(PointeeRD->getDestructor(), StartLoc,
                           /*IsDelete=*/true, /*CallCanBeVirtual=*/true,
                           /*WarnOnNonAbstractTypes=*/!ArrayForm,
                           SourceLocation());
    }
 
    if (!OperatorDelete) {
      if (getLangOpts().OpenCLCPlusPlus) {
        Diag(StartLoc, diag::err_openclcxx_not_supported) << "default delete";
        return ExprError();
      }
 
      bool IsComplete = isCompleteType(StartLoc, Pointee);
      bool CanProvideSize =
          IsComplete && (!ArrayForm || UsualArrayDeleteWantsSize ||
                         Pointee.isDestructedType());
      bool Overaligned = hasNewExtendedAlignment(*this, Pointee);
 
      // Look for a global declaration.
      OperatorDelete = FindUsualDeallocationFunction(StartLoc, CanProvideSize,
                                                     Overaligned, DeleteName);
    }
 
    MarkFunctionReferenced(StartLoc, OperatorDelete);
 
    // Check access and ambiguity of destructor if we're going to call it.
    // Note that this is required even for a virtual delete.
    bool IsVirtualDelete = false;
    if (PointeeRD) {
      if (CXXDestructorDecl *Dtor = LookupDestructor(PointeeRD)) {
        CheckDestructorAccess(Ex.get()->getExprLoc(), Dtor,
                              PDiag(diag::err_access_dtor) << PointeeElem);
        IsVirtualDelete = Dtor->isVirtual();
      }
    }
 
    DiagnoseUseOfDecl(OperatorDelete, StartLoc);
 
    // Convert the operand to the type of the first parameter of operator
    // delete. This is only necessary if we selected a destroying operator
    // delete that we are going to call (non-virtually); converting to void*
    // is trivial and left to AST consumers to handle.
    QualType ParamType = OperatorDelete->getParamDecl(0)->getType();
    if (!IsVirtualDelete && !ParamType->getPointeeType()->isVoidType()) {
      Qualifiers Qs = Pointee.getQualifiers();
      if (Qs.hasCVRQualifiers()) {
        // Qualifiers are irrelevant to this conversion; we're only looking
        // for access and ambiguity.
        Qs.removeCVRQualifiers();
        QualType Unqual = Context.getPointerType(
            Context.getQualifiedType(Pointee.getUnqualifiedType(), Qs));
        Ex = ImpCastExprToType(Ex.get(), Unqual, CK_NoOp);
      }
      Ex = PerformImplicitConversion(Ex.get(), ParamType, AA_Passing);
      if (Ex.isInvalid())
        return ExprError();
    }
  }
 
  CXXDeleteExpr *Result = new (Context) CXXDeleteExpr(
      Context.VoidTy, UseGlobal, ArrayForm, ArrayFormAsWritten,
      UsualArrayDeleteWantsSize, OperatorDelete, Ex.get(), StartLoc);
  AnalyzeDeleteExprMismatch(Result);
  return Result;
}
 
static bool resolveBuiltinNewDeleteOverload(Sema &S, CallExpr *TheCall,
                                            bool IsDelete,
                                            FunctionDecl *&Operator) {
 
  DeclarationName NewName = S.Context.DeclarationNames.getCXXOperatorName(
      IsDelete ? OO_Delete : OO_New);
 
  LookupResult R(S, NewName, TheCall->getBeginLoc(), Sema::LookupOrdinaryName);
  S.LookupQualifiedName(R, S.Context.getTranslationUnitDecl());
  assert(!R.empty() && "implicitly declared allocation functions not found");
  assert(!R.isAmbiguous() && "global allocation functions are ambiguous");
 
  // We do our own custom access checks below.
  R.suppressDiagnostics();
 
  SmallVector<Expr *, 8> Args(TheCall->arg_begin(), TheCall->arg_end());
  OverloadCandidateSet Candidates(R.getNameLoc(),
                                  OverloadCandidateSet::CSK_Normal);
  for (LookupResult::iterator FnOvl = R.begin(), FnOvlEnd = R.end();
       FnOvl != FnOvlEnd; ++FnOvl) {
    // Even member operator new/delete are implicitly treated as
    // static, so don't use AddMemberCandidate.
    NamedDecl *D = (*FnOvl)->getUnderlyingDecl();
 
    if (FunctionTemplateDecl *FnTemplate = dyn_cast<FunctionTemplateDecl>(D)) {
      S.AddTemplateOverloadCandidate(FnTemplate, FnOvl.getPair(),
                                     /*ExplicitTemplateArgs=*/nullptr, Args,
                                     Candidates,
                                     /*SuppressUserConversions=*/false);
      continue;
    }
 
    FunctionDecl *Fn = cast<FunctionDecl>(D);
    S.AddOverloadCandidate(Fn, FnOvl.getPair(), Args, Candidates,
                           /*SuppressUserConversions=*/false);
  }
 
  SourceRange Range = TheCall->getSourceRange();
 
  // Do the resolution.
  OverloadCandidateSet::iterator Best;
  switch (Candidates.BestViableFunction(S, R.getNameLoc(), Best)) {
  case OR_Success: {
    // Got one!
    FunctionDecl *FnDecl = Best->Function;
    assert(R.getNamingClass() == nullptr &&
           "class members should not be considered");
 
    if (!FnDecl->isReplaceableGlobalAllocationFunction()) {
      S.Diag(R.getNameLoc(), diag::err_builtin_operator_new_delete_not_usual)
          << (IsDelete ? 1 : 0) << Range;
      S.Diag(FnDecl->getLocation(), diag::note_non_usual_function_declared_here)
          << R.getLookupName() << FnDecl->getSourceRange();
      return true;
    }
 
    Operator = FnDecl;
    return false;
  }
 
  case OR_No_Viable_Function:
    Candidates.NoteCandidates(
        PartialDiagnosticAt(R.getNameLoc(),
                            S.PDiag(diag::err_ovl_no_viable_function_in_call)
                                << R.getLookupName() << Range),
        S, OCD_AllCandidates, Args);
    return true;
 
  case OR_Ambiguous:
    Candidates.NoteCandidates(
        PartialDiagnosticAt(R.getNameLoc(),
                            S.PDiag(diag::err_ovl_ambiguous_call)
                                << R.getLookupName() << Range),
        S, OCD_AmbiguousCandidates, Args);
    return true;
 
  case OR_Deleted: {
    Candidates.NoteCandidates(
        PartialDiagnosticAt(R.getNameLoc(), S.PDiag(diag::err_ovl_deleted_call)
                                                << R.getLookupName() << Range),
        S, OCD_AllCandidates, Args);
    return true;
  }
  }
  llvm_unreachable("Unreachable, bad result from BestViableFunction");
}
 
ExprResult
Sema::SemaBuiltinOperatorNewDeleteOverloaded(ExprResult TheCallResult,
                                             bool IsDelete) {
  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
  if (!getLangOpts().CPlusPlus) {
    Diag(TheCall->getExprLoc(), diag::err_builtin_requires_language)
        << (IsDelete ? "__builtin_operator_delete" : "__builtin_operator_new")
        << "C++";
    return ExprError();
  }
  // CodeGen assumes it can find the global new and delete to call,
  // so ensure that they are declared.
  DeclareGlobalNewDelete();
 
  FunctionDecl *OperatorNewOrDelete = nullptr;
  if (resolveBuiltinNewDeleteOverload(*this, TheCall, IsDelete,
                                      OperatorNewOrDelete))
    return ExprError();
  assert(OperatorNewOrDelete && "should be found");
 
  DiagnoseUseOfDecl(OperatorNewOrDelete, TheCall->getExprLoc());
  MarkFunctionReferenced(TheCall->getExprLoc(), OperatorNewOrDelete);
 
  TheCall->setType(OperatorNewOrDelete->getReturnType());
  for (unsigned i = 0; i != TheCall->getNumArgs(); ++i) {
    QualType ParamTy = OperatorNewOrDelete->getParamDecl(i)->getType();
    InitializedEntity Entity =
        InitializedEntity::InitializeParameter(Context, ParamTy, false);
    ExprResult Arg = PerformCopyInitialization(
        Entity, TheCall->getArg(i)->getBeginLoc(), TheCall->getArg(i));
    if (Arg.isInvalid())
      return ExprError();
    TheCall->setArg(i, Arg.get());
  }
  auto Callee = dyn_cast<ImplicitCastExpr>(TheCall->getCallee());
  assert(Callee && Callee->getCastKind() == CK_BuiltinFnToFnPtr &&
         "Callee expected to be implicit cast to a builtin function pointer");
  Callee->setType(OperatorNewOrDelete->getType());
 
  return TheCallResult;
}
 
void Sema::CheckVirtualDtorCall(CXXDestructorDecl *dtor, SourceLocation Loc,
                                bool IsDelete, bool CallCanBeVirtual,
                                bool WarnOnNonAbstractTypes,
                                SourceLocation DtorLoc) {
  if (!dtor || dtor->isVirtual() || !CallCanBeVirtual || isUnevaluatedContext())
    return;
 
  // C++ [expr.delete]p3:
  //   In the first alternative (delete object), if the static type of the
  //   object to be deleted is different from its dynamic type, the static
  //   type shall be a base class of the dynamic type of the object to be
  //   deleted and the static type shall have a virtual destructor or the
  //   behavior is undefined.
  //
  const CXXRecordDecl *PointeeRD = dtor->getParent();
  // Note: a final class cannot be derived from, no issue there
  if (!PointeeRD->isPolymorphic() || PointeeRD->hasAttr<FinalAttr>())
    return;
 
  // If the superclass is in a system header, there's nothing that can be done.
  // The `delete` (where we emit the warning) can be in a system header,
  // what matters for this warning is where the deleted type is defined.
  if (getSourceManager().isInSystemHeader(PointeeRD->getLocation()))
    return;
 
  QualType ClassType = dtor->getThisType()->getPointeeType();
  if (PointeeRD->isAbstract()) {
    // If the class is abstract, we warn by default, because we're
    // sure the code has undefined behavior.
    Diag(Loc, diag::warn_delete_abstract_non_virtual_dtor) << (IsDelete ? 0 : 1)
                                                           << ClassType;
  } else if (WarnOnNonAbstractTypes) {
    // Otherwise, if this is not an array delete, it's a bit suspect,
    // but not necessarily wrong.
    Diag(Loc, diag::warn_delete_non_virtual_dtor) << (IsDelete ? 0 : 1)
                                                  << ClassType;
  }
  if (!IsDelete) {
    std::string TypeStr;
    ClassType.getAsStringInternal(TypeStr, getPrintingPolicy());
    Diag(DtorLoc, diag::note_delete_non_virtual)
        << FixItHint::CreateInsertion(DtorLoc, TypeStr + "::");
  }
}
 
Sema::ConditionResult Sema::ActOnConditionVariable(Decl *ConditionVar,
                                                   SourceLocation StmtLoc,
                                                   ConditionKind CK) {
  ExprResult E =
      CheckConditionVariable(cast<VarDecl>(ConditionVar), StmtLoc, CK);
  if (E.isInvalid())
    return ConditionError();
  return ConditionResult(*this, ConditionVar, MakeFullExpr(E.get(), StmtLoc),
                         CK == ConditionKind::ConstexprIf);
}
 
/// Check the use of the given variable as a C++ condition in an if,
/// while, do-while, or switch statement.
ExprResult Sema::CheckConditionVariable(VarDecl *ConditionVar,
                                        SourceLocation StmtLoc,
                                        ConditionKind CK) {
  if (ConditionVar->isInvalidDecl())
    return ExprError();
 
  QualType T = ConditionVar->getType();
 
  // C++ [stmt.select]p2:
  //   The declarator shall not specify a function or an array.
  if (T->isFunctionType())
    return ExprError(Diag(ConditionVar->getLocation(),
                          diag::err_invalid_use_of_function_type)
                       << ConditionVar->getSourceRange());
  else if (T->isArrayType())
    return ExprError(Diag(ConditionVar->getLocation(),
                          diag::err_invalid_use_of_array_type)
                     << ConditionVar->getSourceRange());
 
  ExprResult Condition = BuildDeclRefExpr(
      ConditionVar, ConditionVar->getType().getNonReferenceType(), VK_LValue,
      ConditionVar->getLocation());
 
  switch (CK) {
  case ConditionKind::Boolean:
    return CheckBooleanCondition(StmtLoc, Condition.get());
 
  case ConditionKind::ConstexprIf:
    return CheckBooleanCondition(StmtLoc, Condition.get(), true);
 
  case ConditionKind::Switch:
    return CheckSwitchCondition(StmtLoc, Condition.get());
  }
 
  llvm_unreachable("unexpected condition kind");
}
 
/// CheckCXXBooleanCondition - Returns true if a conversion to bool is invalid.
ExprResult Sema::CheckCXXBooleanCondition(Expr *CondExpr, bool IsConstexpr) {
  // C++11 6.4p4:
  // The value of a condition that is an initialized declaration in a statement
  // other than a switch statement is the value of the declared variable
  // implicitly converted to type bool. If that conversion is ill-formed, the
  // program is ill-formed.
  // The value of a condition that is an expression is the value of the
  // expression, implicitly converted to bool.
  //
  // C++2b 8.5.2p2
  // If the if statement is of the form if constexpr, the value of the condition
  // is contextually converted to bool and the converted expression shall be
  // a constant expression.
  //
 
  ExprResult E = PerformContextuallyConvertToBool(CondExpr);
  if (!IsConstexpr || E.isInvalid() || E.get()->isValueDependent())
    return E;
 
  // FIXME: Return this value to the caller so they don't need to recompute it.
  llvm::APSInt Cond;
  E = VerifyIntegerConstantExpression(
      E.get(), &Cond,
      diag::err_constexpr_if_condition_expression_is_not_constant);
  return E;
}
 
/// Helper function to determine whether this is the (deprecated) C++
/// conversion from a string literal to a pointer to non-const char or
/// non-const wchar_t (for narrow and wide string literals,
/// respectively).
bool
Sema::IsStringLiteralToNonConstPointerConversion(Expr *From, QualType ToType) {
  // Look inside the implicit cast, if it exists.
  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(From))
    From = Cast->getSubExpr();
 
  // A string literal (2.13.4) that is not a wide string literal can
  // be converted to an rvalue of type "pointer to char"; a wide
  // string literal can be converted to an rvalue of type "pointer
  // to wchar_t" (C++ 4.2p2).
  if (StringLiteral *StrLit = dyn_cast<StringLiteral>(From->IgnoreParens()))
    if (const PointerType *ToPtrType = ToType->getAs<PointerType>())
      if (const BuiltinType *ToPointeeType
          = ToPtrType->getPointeeType()->getAs<BuiltinType>()) {
        // This conversion is considered only when there is an
        // explicit appropriate pointer target type (C++ 4.2p2).
        if (!ToPtrType->getPointeeType().hasQualifiers()) {
          switch (StrLit->getKind()) {
            case StringLiteral::UTF8:
            case StringLiteral::UTF16:
            case StringLiteral::UTF32:
              // We don't allow UTF literals to be implicitly converted
              break;
            case StringLiteral::Ascii:
              return (ToPointeeType->getKind() == BuiltinType::Char_U ||
                      ToPointeeType->getKind() == BuiltinType::Char_S);
            case StringLiteral::Wide:
              return Context.typesAreCompatible(Context.getWideCharType(),
                                                QualType(ToPointeeType, 0));
          }
        }
      }
 
  return false;
}
 
static ExprResult BuildCXXCastArgument(Sema &S,
                                       SourceLocation CastLoc,
                                       QualType Ty,
                                       CastKind Kind,
                                       CXXMethodDecl *Method,
                                       DeclAccessPair FoundDecl,
                                       bool HadMultipleCandidates,
                                       Expr *From) {
  switch (Kind) {
  default: llvm_unreachable("Unhandled cast kind!");
  case CK_ConstructorConversion: {
    CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(Method);
    SmallVector<Expr*, 8> ConstructorArgs;
 
    if (S.RequireNonAbstractType(CastLoc, Ty,
                                 diag::err_allocation_of_abstract_type))
      return ExprError();
 
    if (S.CompleteConstructorCall(Constructor, Ty, From, CastLoc,
                                  ConstructorArgs))
      return ExprError();
 
    S.CheckConstructorAccess(CastLoc, Constructor, FoundDecl,
                             InitializedEntity::InitializeTemporary(Ty));
    if (S.DiagnoseUseOfDecl(Method, CastLoc))
      return ExprError();
 
    ExprResult Result = S.BuildCXXConstructExpr(
        CastLoc, Ty, FoundDecl, cast<CXXConstructorDecl>(Method),
        ConstructorArgs, HadMultipleCandidates,
        /*ListInit*/ false, /*StdInitListInit*/ false, /*ZeroInit*/ false,
        CXXConstructExpr::CK_Complete, SourceRange());
    if (Result.isInvalid())
      return ExprError();
 
    return S.MaybeBindToTemporary(Result.getAs<Expr>());
  }
 
  case CK_UserDefinedConversion: {
    assert(!From->getType()->isPointerType() && "Arg can't have pointer type!");
 
    S.CheckMemberOperatorAccess(CastLoc, From, /*arg*/ nullptr, FoundDecl);
    if (S.DiagnoseUseOfDecl(Method, CastLoc))
      return ExprError();
 
    // Create an implicit call expr that calls it.
    CXXConversionDecl *Conv = cast<CXXConversionDecl>(Method);
    ExprResult Result = S.BuildCXXMemberCallExpr(From, FoundDecl, Conv,
                                                 HadMultipleCandidates);
    if (Result.isInvalid())
      return ExprError();
    // Record usage of conversion in an implicit cast.
    Result = ImplicitCastExpr::Create(S.Context, Result.get()->getType(),
                                      CK_UserDefinedConversion, Result.get(),
                                      nullptr, Result.get()->getValueKind(),
                                      S.CurFPFeatureOverrides());
 
    return S.MaybeBindToTemporary(Result.get());
  }
  }
}
 
/// PerformImplicitConversion - Perform an implicit conversion of the
/// expression From to the type ToType using the pre-computed implicit
/// conversion sequence ICS. Returns the converted
/// expression. Action is the kind of conversion we're performing,
/// used in the error message.
ExprResult
Sema::PerformImplicitConversion(Expr *From, QualType ToType,
                                const ImplicitConversionSequence &ICS,
                                AssignmentAction Action,
                                CheckedConversionKind CCK) {
  // C++ [over.match.oper]p7: [...] operands of class type are converted [...]
  if (CCK == CCK_ForBuiltinOverloadedOp && !From->getType()->isRecordType())
    return From;
 
  switch (ICS.getKind()) {
  case ImplicitConversionSequence::StandardConversion: {
    ExprResult Res = PerformImplicitConversion(From, ToType, ICS.Standard,
                                               Action, CCK);
    if (Res.isInvalid())
      return ExprError();
    From = Res.get();
    break;
  }
 
  case ImplicitConversionSequence::UserDefinedConversion: {
 
      FunctionDecl *FD = ICS.UserDefined.ConversionFunction;
      CastKind CastKind;
      QualType BeforeToType;
      assert(FD && "no conversion function for user-defined conversion seq");
      if (const CXXConversionDecl *Conv = dyn_cast<CXXConversionDecl>(FD)) {
        CastKind = CK_UserDefinedConversion;
 
        // If the user-defined conversion is specified by a conversion function,
        // the initial standard conversion sequence converts the source type to
        // the implicit object parameter of the conversion function.
        BeforeToType = Context.getTagDeclType(Conv->getParent());
      } else {
        const CXXConstructorDecl *Ctor = cast<CXXConstructorDecl>(FD);
        CastKind = CK_ConstructorConversion;
        // Do no conversion if dealing with ... for the first conversion.
        if (!ICS.UserDefined.EllipsisConversion) {
          // If the user-defined conversion is specified by a constructor, the
          // initial standard conversion sequence converts the source type to
          // the type required by the argument of the constructor
          BeforeToType = Ctor->getParamDecl(0)->getType().getNonReferenceType();
        }
      }
      // Watch out for ellipsis conversion.
      if (!ICS.UserDefined.EllipsisConversion) {
        ExprResult Res =
          PerformImplicitConversion(From, BeforeToType,
                                    ICS.UserDefined.Before, AA_Converting,
                                    CCK);
        if (Res.isInvalid())
          return ExprError();
        From = Res.get();
      }
 
      ExprResult CastArg = BuildCXXCastArgument(
          *this, From->getBeginLoc(), ToType.getNonReferenceType(), CastKind,
          cast<CXXMethodDecl>(FD), ICS.UserDefined.FoundConversionFunction,
          ICS.UserDefined.HadMultipleCandidates, From);
 
      if (CastArg.isInvalid())
        return ExprError();
 
      From = CastArg.get();
 
      // C++ [over.match.oper]p7:
      //   [...] the second standard conversion sequence of a user-defined
      //   conversion sequence is not applied.
      if (CCK == CCK_ForBuiltinOverloadedOp)
        return From;
 
      return PerformImplicitConversion(From, ToType, ICS.UserDefined.After,
                                       AA_Converting, CCK);
  }
 
  case ImplicitConversionSequence::AmbiguousConversion:
    ICS.DiagnoseAmbiguousConversion(*this, From->getExprLoc(),
                          PDiag(diag::err_typecheck_ambiguous_condition)
                            << From->getSourceRange());
    return ExprError();
 
  case ImplicitConversionSequence::EllipsisConversion:
    llvm_unreachable("Cannot perform an ellipsis conversion");
 
  case ImplicitConversionSequence::BadConversion:
    Sema::AssignConvertType ConvTy =
        CheckAssignmentConstraints(From->getExprLoc(), ToType, From->getType());
    bool Diagnosed = DiagnoseAssignmentResult(
        ConvTy == Compatible ? Incompatible : ConvTy, From->getExprLoc(),
        ToType, From->getType(), From, Action);
    assert(Diagnosed && "failed to diagnose bad conversion"); (void)Diagnosed;
    return ExprError();
  }
 
  // Everything went well.
  return From;
}
 
/// PerformImplicitConversion - Perform an implicit conversion of the
/// expression From to the type ToType by following the standard
/// conversion sequence SCS. Returns the converted
/// expression. Flavor is the context in which we're performing this
/// conversion, for use in error messages.
ExprResult
Sema::PerformImplicitConversion(Expr *From, QualType ToType,
                                const StandardConversionSequence& SCS,
                                AssignmentAction Action,
                                CheckedConversionKind CCK) {
  bool CStyle = (CCK == CCK_CStyleCast || CCK == CCK_FunctionalCast);
 
  // Overall FIXME: we are recomputing too many types here and doing far too
  // much extra work. What this means is that we need to keep track of more
  // information that is computed when we try the implicit conversion initially,
  // so that we don't need to recompute anything here.
  QualType FromType = From->getType();
 
  if (SCS.CopyConstructor) {
    // FIXME: When can ToType be a reference type?
    assert(!ToType->isReferenceType());
    if (SCS.Second == ICK_Derived_To_Base) {
      SmallVector<Expr*, 8> ConstructorArgs;
      if (CompleteConstructorCall(
              cast<CXXConstructorDecl>(SCS.CopyConstructor), ToType, From,
              /*FIXME:ConstructLoc*/ SourceLocation(), ConstructorArgs))
        return ExprError();
      return BuildCXXConstructExpr(
          /*FIXME:ConstructLoc*/ SourceLocation(), ToType,
          SCS.FoundCopyConstructor, SCS.CopyConstructor,
          ConstructorArgs, /*HadMultipleCandidates*/ false,
          /*ListInit*/ false, /*StdInitListInit*/ false, /*ZeroInit*/ false,
          CXXConstructExpr::CK_Complete, SourceRange());
    }
    return BuildCXXConstructExpr(
        /*FIXME:ConstructLoc*/ SourceLocation(), ToType,
        SCS.FoundCopyConstructor, SCS.CopyConstructor,
        From, /*HadMultipleCandidates*/ false,
        /*ListInit*/ false, /*StdInitListInit*/ false, /*ZeroInit*/ false,
        CXXConstructExpr::CK_Complete, SourceRange());
  }
 
  // Resolve overloaded function references.
  if (Context.hasSameType(FromType, Context.OverloadTy)) {
    DeclAccessPair Found;
    FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(From, ToType,
                                                          true, Found);
    if (!Fn)
      return ExprError();
 
    if (DiagnoseUseOfDecl(Fn, From->getBeginLoc()))
      return ExprError();
 
    From = FixOverloadedFunctionReference(From, Found, Fn);
    FromType = From->getType();
  }
 
  // If we're converting to an atomic type, first convert to the corresponding
  // non-atomic type.
  QualType ToAtomicType;
  if (const AtomicType *ToAtomic = ToType->getAs<AtomicType>()) {
    ToAtomicType = ToType;
    ToType = ToAtomic->getValueType();
  }
 
  QualType InitialFromType = FromType;
  // Perform the first implicit conversion.
  switch (SCS.First) {
  case ICK_Identity:
    if (const AtomicType *FromAtomic = FromType->getAs<AtomicType>()) {
      FromType = FromAtomic->getValueType().getUnqualifiedType();
      From = ImplicitCastExpr::Create(Context, FromType, CK_AtomicToNonAtomic,
                                      From, /*BasePath=*/nullptr, VK_PRValue,
                                      FPOptionsOverride());
    }
    break;
 
  case ICK_Lvalue_To_Rvalue: {
    assert(From->getObjectKind() != OK_ObjCProperty);
    ExprResult FromRes = DefaultLvalueConversion(From);
    if (FromRes.isInvalid())
      return ExprError();
 
    From = FromRes.get();
    FromType = From->getType();
    break;
  }
 
  case ICK_Array_To_Pointer:
    FromType = Context.getArrayDecayedType(FromType);
    From = ImpCastExprToType(From, FromType, CK_ArrayToPointerDecay, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_Function_To_Pointer:
    FromType = Context.getPointerType(FromType);
    From = ImpCastExprToType(From, FromType, CK_FunctionToPointerDecay,
                             VK_PRValue, /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  default:
    llvm_unreachable("Improper first standard conversion");
  }
 
  // Perform the second implicit conversion
  switch (SCS.Second) {
  case ICK_Identity:
    // C++ [except.spec]p5:
    //   [For] assignment to and initialization of pointers to functions,
    //   pointers to member functions, and references to functions: the
    //   target entity shall allow at least the exceptions allowed by the
    //   source value in the assignment or initialization.
    switch (Action) {
    case AA_Assigning:
    case AA_Initializing:
      // Note, function argument passing and returning are initialization.
    case AA_Passing:
    case AA_Returning:
    case AA_Sending:
    case AA_Passing_CFAudited:
      if (CheckExceptionSpecCompatibility(From, ToType))
        return ExprError();
      break;
 
    case AA_Casting:
    case AA_Converting:
      // Casts and implicit conversions are not initialization, so are not
      // checked for exception specification mismatches.
      break;
    }
    // Nothing else to do.
    break;
 
  case ICK_Integral_Promotion:
  case ICK_Integral_Conversion:
    if (ToType->isBooleanType()) {
      assert(FromType->castAs<EnumType>()->getDecl()->isFixed() &&
             SCS.Second == ICK_Integral_Promotion &&
             "only enums with fixed underlying type can promote to bool");
      From = ImpCastExprToType(From, ToType, CK_IntegralToBoolean, VK_PRValue,
                               /*BasePath=*/nullptr, CCK)
                 .get();
    } else {
      From = ImpCastExprToType(From, ToType, CK_IntegralCast, VK_PRValue,
                               /*BasePath=*/nullptr, CCK)
                 .get();
    }
    break;
 
  case ICK_Floating_Promotion:
  case ICK_Floating_Conversion:
    From = ImpCastExprToType(From, ToType, CK_FloatingCast, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_Complex_Promotion:
  case ICK_Complex_Conversion: {
    QualType FromEl = From->getType()->castAs<ComplexType>()->getElementType();
    QualType ToEl = ToType->castAs<ComplexType>()->getElementType();
    CastKind CK;
    if (FromEl->isRealFloatingType()) {
      if (ToEl->isRealFloatingType())
        CK = CK_FloatingComplexCast;
      else
        CK = CK_FloatingComplexToIntegralComplex;
    } else if (ToEl->isRealFloatingType()) {
      CK = CK_IntegralComplexToFloatingComplex;
    } else {
      CK = CK_IntegralComplexCast;
    }
    From = ImpCastExprToType(From, ToType, CK, VK_PRValue, /*BasePath=*/nullptr,
                             CCK)
               .get();
    break;
  }
 
  case ICK_Floating_Integral:
    if (ToType->isRealFloatingType())
      From = ImpCastExprToType(From, ToType, CK_IntegralToFloating, VK_PRValue,
                               /*BasePath=*/nullptr, CCK)
                 .get();
    else
      From = ImpCastExprToType(From, ToType, CK_FloatingToIntegral, VK_PRValue,
                               /*BasePath=*/nullptr, CCK)
                 .get();
    break;
 
  case ICK_Compatible_Conversion:
    From = ImpCastExprToType(From, ToType, CK_NoOp, From->getValueKind(),
                             /*BasePath=*/nullptr, CCK).get();
    break;
 
  case ICK_Writeback_Conversion:
  case ICK_Pointer_Conversion: {
    if (SCS.IncompatibleObjC && Action != AA_Casting) {
      // Diagnose incompatible Objective-C conversions
      if (Action == AA_Initializing || Action == AA_Assigning)
        Diag(From->getBeginLoc(),
             diag::ext_typecheck_convert_incompatible_pointer)
            << ToType << From->getType() << Action << From->getSourceRange()
            << 0;
      else
        Diag(From->getBeginLoc(),
             diag::ext_typecheck_convert_incompatible_pointer)
            << From->getType() << ToType << Action << From->getSourceRange()
            << 0;
 
      if (From->getType()->isObjCObjectPointerType() &&
          ToType->isObjCObjectPointerType())
        EmitRelatedResultTypeNote(From);
    } else if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
               !CheckObjCARCUnavailableWeakConversion(ToType,
                                                      From->getType())) {
      if (Action == AA_Initializing)
        Diag(From->getBeginLoc(), diag::err_arc_weak_unavailable_assign);
      else
        Diag(From->getBeginLoc(), diag::err_arc_convesion_of_weak_unavailable)
            << (Action == AA_Casting) << From->getType() << ToType
            << From->getSourceRange();
    }
 
    // Defer address space conversion to the third conversion.
    QualType FromPteeType = From->getType()->getPointeeType();
    QualType ToPteeType = ToType->getPointeeType();
    QualType NewToType = ToType;
    if (!FromPteeType.isNull() && !ToPteeType.isNull() &&
        FromPteeType.getAddressSpace() != ToPteeType.getAddressSpace()) {
      NewToType = Context.removeAddrSpaceQualType(ToPteeType);
      NewToType = Context.getAddrSpaceQualType(NewToType,
                                               FromPteeType.getAddressSpace());
      if (ToType->isObjCObjectPointerType())
        NewToType = Context.getObjCObjectPointerType(NewToType);
      else if (ToType->isBlockPointerType())
        NewToType = Context.getBlockPointerType(NewToType);
      else
        NewToType = Context.getPointerType(NewToType);
    }
 
    CastKind Kind;
    CXXCastPath BasePath;
    if (CheckPointerConversion(From, NewToType, Kind, BasePath, CStyle))
      return ExprError();
 
    // Make sure we extend blocks if necessary.
    // FIXME: doing this here is really ugly.
    if (Kind == CK_BlockPointerToObjCPointerCast) {
      ExprResult E = From;
      (void) PrepareCastToObjCObjectPointer(E);
      From = E.get();
    }
    if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
      CheckObjCConversion(SourceRange(), NewToType, From, CCK);
    From = ImpCastExprToType(From, NewToType, Kind, VK_PRValue, &BasePath, CCK)
               .get();
    break;
  }
 
  case ICK_Pointer_Member: {
    CastKind Kind;
    CXXCastPath BasePath;
    if (CheckMemberPointerConversion(From, ToType, Kind, BasePath, CStyle))
      return ExprError();
    if (CheckExceptionSpecCompatibility(From, ToType))
      return ExprError();
 
    // We may not have been able to figure out what this member pointer resolved
    // to up until this exact point.  Attempt to lock-in it's inheritance model.
    if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
      (void)isCompleteType(From->getExprLoc(), From->getType());
      (void)isCompleteType(From->getExprLoc(), ToType);
    }
 
    From =
        ImpCastExprToType(From, ToType, Kind, VK_PRValue, &BasePath, CCK).get();
    break;
  }
 
  case ICK_Boolean_Conversion:
    // Perform half-to-boolean conversion via float.
    if (From->getType()->isHalfType()) {
      From = ImpCastExprToType(From, Context.FloatTy, CK_FloatingCast).get();
      FromType = Context.FloatTy;
    }
 
    From = ImpCastExprToType(From, Context.BoolTy,
                             ScalarTypeToBooleanCastKind(FromType), VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_Derived_To_Base: {
    CXXCastPath BasePath;
    if (CheckDerivedToBaseConversion(
            From->getType(), ToType.getNonReferenceType(), From->getBeginLoc(),
            From->getSourceRange(), &BasePath, CStyle))
      return ExprError();
 
    From = ImpCastExprToType(From, ToType.getNonReferenceType(),
                      CK_DerivedToBase, From->getValueKind(),
                      &BasePath, CCK).get();
    break;
  }
 
  case ICK_Vector_Conversion:
    From = ImpCastExprToType(From, ToType, CK_BitCast, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_SVE_Vector_Conversion:
    From = ImpCastExprToType(From, ToType, CK_BitCast, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_Vector_Splat: {
    // Vector splat from any arithmetic type to a vector.
    Expr *Elem = prepareVectorSplat(ToType, From).get();
    From = ImpCastExprToType(Elem, ToType, CK_VectorSplat, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
  }
 
  case ICK_Complex_Real:
    // Case 1.  x -> _Complex y
    if (const ComplexType *ToComplex = ToType->getAs<ComplexType>()) {
      QualType ElType = ToComplex->getElementType();
      bool isFloatingComplex = ElType->isRealFloatingType();
 
      // x -> y
      if (Context.hasSameUnqualifiedType(ElType, From->getType())) {
        // do nothing
      } else if (From->getType()->isRealFloatingType()) {
        From = ImpCastExprToType(From, ElType,
                isFloatingComplex ? CK_FloatingCast : CK_FloatingToIntegral).get();
      } else {
        assert(From->getType()->isIntegerType());
        From = ImpCastExprToType(From, ElType,
                isFloatingComplex ? CK_IntegralToFloating : CK_IntegralCast).get();
      }
      // y -> _Complex y
      From = ImpCastExprToType(From, ToType,
                   isFloatingComplex ? CK_FloatingRealToComplex
                                     : CK_IntegralRealToComplex).get();
 
    // Case 2.  _Complex x -> y
    } else {
      auto *FromComplex = From->getType()->castAs<ComplexType>();
      QualType ElType = FromComplex->getElementType();
      bool isFloatingComplex = ElType->isRealFloatingType();
 
      // _Complex x -> x
      From = ImpCastExprToType(From, ElType,
                               isFloatingComplex ? CK_FloatingComplexToReal
                                                 : CK_IntegralComplexToReal,
                               VK_PRValue, /*BasePath=*/nullptr, CCK)
                 .get();
 
      // x -> y
      if (Context.hasSameUnqualifiedType(ElType, ToType)) {
        // do nothing
      } else if (ToType->isRealFloatingType()) {
        From = ImpCastExprToType(From, ToType,
                                 isFloatingComplex ? CK_FloatingCast
                                                   : CK_IntegralToFloating,
                                 VK_PRValue, /*BasePath=*/nullptr, CCK)
                   .get();
      } else {
        assert(ToType->isIntegerType());
        From = ImpCastExprToType(From, ToType,
                                 isFloatingComplex ? CK_FloatingToIntegral
                                                   : CK_IntegralCast,
                                 VK_PRValue, /*BasePath=*/nullptr, CCK)
                   .get();
      }
    }
    break;
 
  case ICK_Block_Pointer_Conversion: {
    LangAS AddrSpaceL =
        ToType->castAs<BlockPointerType>()->getPointeeType().getAddressSpace();
    LangAS AddrSpaceR =
        FromType->castAs<BlockPointerType>()->getPointeeType().getAddressSpace();
    assert(Qualifiers::isAddressSpaceSupersetOf(AddrSpaceL, AddrSpaceR) &&
           "Invalid cast");
    CastKind Kind =
        AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
    From = ImpCastExprToType(From, ToType.getUnqualifiedType(), Kind,
                             VK_PRValue, /*BasePath=*/nullptr, CCK)
               .get();
    break;
  }
 
  case ICK_TransparentUnionConversion: {
    ExprResult FromRes = From;
    Sema::AssignConvertType ConvTy =
      CheckTransparentUnionArgumentConstraints(ToType, FromRes);
    if (FromRes.isInvalid())
      return ExprError();
    From = FromRes.get();
    assert ((ConvTy == Sema::Compatible) &&
            "Improper transparent union conversion");
    (void)ConvTy;
    break;
  }
 
  case ICK_Zero_Event_Conversion:
  case ICK_Zero_Queue_Conversion:
    From = ImpCastExprToType(From, ToType,
                             CK_ZeroToOCLOpaqueType,
                             From->getValueKind()).get();
    break;
 
  case ICK_Lvalue_To_Rvalue:
  case ICK_Array_To_Pointer:
  case ICK_Function_To_Pointer:
  case ICK_Function_Conversion:
  case ICK_Qualification:
  case ICK_Num_Conversion_Kinds:
  case ICK_C_Only_Conversion:
  case ICK_Incompatible_Pointer_Conversion:
    llvm_unreachable("Improper second standard conversion");
  }
 
  switch (SCS.Third) {
  case ICK_Identity:
    // Nothing to do.
    break;
 
  case ICK_Function_Conversion:
    // If both sides are functions (or pointers/references to them), there could
    // be incompatible exception declarations.
    if (CheckExceptionSpecCompatibility(From, ToType))
      return ExprError();
 
    From = ImpCastExprToType(From, ToType, CK_NoOp, VK_PRValue,
                             /*BasePath=*/nullptr, CCK)
               .get();
    break;
 
  case ICK_Qualification: {
    ExprValueKind VK = From->getValueKind();
    CastKind CK = CK_NoOp;
 
    if (ToType->isReferenceType() &&
        ToType->getPointeeType().getAddressSpace() !=
            From->getType().getAddressSpace())
      CK = CK_AddressSpaceConversion;
 
    if (ToType->isPointerType() &&
        ToType->getPointeeType().getAddressSpace() !=
            From->getType()->getPointeeType().getAddressSpace())
      CK = CK_AddressSpaceConversion;
 
    From = ImpCastExprToType(From, ToType.getNonLValueExprType(Context), CK, VK,
                             /*BasePath=*/nullptr, CCK)
               .get();
 
    if (SCS.DeprecatedStringLiteralToCharPtr &&
        !getLangOpts().WritableStrings) {
      Diag(From->getBeginLoc(),
           getLangOpts().CPlusPlus11
               ? diag::ext_deprecated_string_literal_conversion
               : diag::warn_deprecated_string_literal_conversion)
          << ToType.getNonReferenceType();
    }
 
    break;
  }
 
  default:
    llvm_unreachable("Improper third standard conversion");
  }
 
  // If this conversion sequence involved a scalar -> atomic conversion, perform
  // that conversion now.
  if (!ToAtomicType.isNull()) {
    assert(Context.hasSameType(
        ToAtomicType->castAs<AtomicType>()->getValueType(), From->getType()));
    From = ImpCastExprToType(From, ToAtomicType, CK_NonAtomicToAtomic,
                             VK_PRValue, nullptr, CCK)
               .get();
  }
 
  // Materialize a temporary if we're implicitly converting to a reference
  // type. This is not required by the C++ rules but is necessary to maintain
  // AST invariants.
  if (ToType->isReferenceType() && From->isPRValue()) {
    ExprResult Res = TemporaryMaterializationConversion(From);
    if (Res.isInvalid())
      return ExprError();
    From = Res.get();
  }
 
  // If this conversion sequence succeeded and involved implicitly converting a
  // _Nullable type to a _Nonnull one, complain.
  if (!isCast(CCK))
    diagnoseNullableToNonnullConversion(ToType, InitialFromType,
                                        From->getBeginLoc());
 
  return From;
}
 
/// Check the completeness of a type in a unary type trait.
///
/// If the particular type trait requires a complete type, tries to complete
/// it. If completing the type fails, a diagnostic is emitted and false
/// returned. If completing the type succeeds or no completion was required,
/// returns true.
static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S, TypeTrait UTT,
                                                SourceLocation Loc,
                                                QualType ArgTy) {
  // C++0x [meta.unary.prop]p3:
  //   For all of the class templates X declared in this Clause, instantiating
  //   that template with a template argument that is a class template
  //   specialization may result in the implicit instantiation of the template
  //   argument if and only if the semantics of X require that the argument
  //   must be a complete type.
  // We apply this rule to all the type trait expressions used to implement
  // these class templates. We also try to follow any GCC documented behavior
  // in these expressions to ensure portability of standard libraries.
  switch (UTT) {
  default: llvm_unreachable("not a UTT");
    // is_complete_type somewhat obviously cannot require a complete type.
  case UTT_IsCompleteType:
    // Fall-through
 
    // These traits are modeled on the type predicates in C++0x
    // [meta.unary.cat] and [meta.unary.comp]. They are not specified as
    // requiring a complete type, as whether or not they return true cannot be
    // impacted by the completeness of the type.
  case UTT_IsVoid:
  case UTT_IsIntegral:
  case UTT_IsFloatingPoint:
  case UTT_IsArray:
  case UTT_IsPointer:
  case UTT_IsLvalueReference:
  case UTT_IsRvalueReference:
  case UTT_IsMemberFunctionPointer:
  case UTT_IsMemberObjectPointer:
  case UTT_IsEnum:
  case UTT_IsUnion:
  case UTT_IsClass:
  case UTT_IsFunction:
  case UTT_IsReference:
  case UTT_IsArithmetic:
  case UTT_IsFundamental:
  case UTT_IsObject:
  case UTT_IsScalar:
  case UTT_IsCompound:
  case UTT_IsMemberPointer:
    // Fall-through
 
    // These traits are modeled on type predicates in C++0x [meta.unary.prop]
    // which requires some of its traits to have the complete type. However,
    // the completeness of the type cannot impact these traits' semantics, and
    // so they don't require it. This matches the comments on these traits in
    // Table 49.
  case UTT_IsConst:
  case UTT_IsVolatile:
  case UTT_IsSigned:
  case UTT_IsUnsigned:
 
  // This type trait always returns false, checking the type is moot.
  case UTT_IsInterfaceClass:
    return true;
 
  // C++14 [meta.unary.prop]:
  //   If T is a non-union class type, T shall be a complete type.
  case UTT_IsEmpty:
  case UTT_IsPolymorphic:
  case UTT_IsAbstract:
    if (const auto *RD = ArgTy->getAsCXXRecordDecl())
      if (!RD->isUnion())
        return !S.RequireCompleteType(
            Loc, ArgTy, diag::err_incomplete_type_used_in_type_trait_expr);
    return true;
 
  // C++14 [meta.unary.prop]:
  //   If T is a class type, T shall be a complete type.
  case UTT_IsFinal:
  case UTT_IsSealed:
    if (ArgTy->getAsCXXRecordDecl())
      return !S.RequireCompleteType(
          Loc, ArgTy, diag::err_incomplete_type_used_in_type_trait_expr);
    return true;
 
  // C++1z [meta.unary.prop]:
  //   remove_all_extents_t<T> shall be a complete type or cv void.
  case UTT_IsAggregate:
  case UTT_IsTrivial:
  case UTT_IsTriviallyCopyable:
  case UTT_IsStandardLayout:
  case UTT_IsPOD:
  case UTT_IsLiteral:
  // Per the GCC type traits documentation, T shall be a complete type, cv void,
  // or an array of unknown bound. But GCC actually imposes the same constraints
  // as above.
  case UTT_HasNothrowAssign:
  case UTT_HasNothrowMoveAssign:
  case UTT_HasNothrowConstructor:
  case UTT_HasNothrowCopy:
  case UTT_HasTrivialAssign:
  case UTT_HasTrivialMoveAssign:
  case UTT_HasTrivialDefaultConstructor:
  case UTT_HasTrivialMoveConstructor:
  case UTT_HasTrivialCopy:
  case UTT_HasTrivialDestructor:
  case UTT_HasVirtualDestructor:
    ArgTy = QualType(ArgTy->getBaseElementTypeUnsafe(), 0);
    LLVM_FALLTHROUGH;
 
  // C++1z [meta.unary.prop]:
  //   T shall be a complete type, cv void, or an array of unknown bound.
  case UTT_IsDestructible:
  case UTT_IsNothrowDestructible:
  case UTT_IsTriviallyDestructible:
  case UTT_HasUniqueObjectRepresentations:
    if (ArgTy->isIncompleteArrayType() || ArgTy->isVoidType())
      return true;
 
    return !S.RequireCompleteType(
        Loc, ArgTy, diag::err_incomplete_type_used_in_type_trait_expr);
  }
}
 
static bool HasNoThrowOperator(const RecordType *RT, OverloadedOperatorKind Op,
                               Sema &Self, SourceLocation KeyLoc, ASTContext &C,
                               bool (CXXRecordDecl::*HasTrivial)() const,
                               bool (CXXRecordDecl::*HasNonTrivial)() const,
                               bool (CXXMethodDecl::*IsDesiredOp)() const)
{
  CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
  if ((RD->*HasTrivial)() && !(RD->*HasNonTrivial)())
    return true;
 
  DeclarationName Name = C.DeclarationNames.getCXXOperatorName(Op);
  DeclarationNameInfo NameInfo(Name, KeyLoc);
  LookupResult Res(Self, NameInfo, Sema::LookupOrdinaryName);
  if (Self.LookupQualifiedName(Res, RD)) {
    bool FoundOperator = false;
    Res.suppressDiagnostics();
    for (LookupResult::iterator Op = Res.begin(), OpEnd = Res.end();
         Op != OpEnd; ++Op) {
      if (isa<FunctionTemplateDecl>(*Op))
        continue;
 
      CXXMethodDecl *Operator = cast<CXXMethodDecl>(*Op);
      if((Operator->*IsDesiredOp)()) {
        FoundOperator = true;
        auto *CPT = Operator->getType()->castAs<FunctionProtoType>();
        CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
        if (!CPT || !CPT->isNothrow())
          return false;
      }
    }
    return FoundOperator;
  }
  return false;
}
 
static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
                                   SourceLocation KeyLoc, QualType T) {
  assert(!T->isDependentType() && "Cannot evaluate traits of dependent type");
 
  ASTContext &C = Self.Context;
  switch(UTT) {
  default: llvm_unreachable("not a UTT");
    // Type trait expressions corresponding to the primary type category
    // predicates in C++0x [meta.unary.cat].
  case UTT_IsVoid:
    return T->isVoidType();
  case UTT_IsIntegral:
    return T->isIntegralType(C);
  case UTT_IsFloatingPoint:
    return T->isFloatingType();
  case UTT_IsArray:
    return T->isArrayType();
  case UTT_IsPointer:
    return T->isAnyPointerType();
  case UTT_IsLvalueReference:
    return T->isLValueReferenceType();
  case UTT_IsRvalueReference:
    return T->isRValueReferenceType();
  case UTT_IsMemberFunctionPointer:
    return T->isMemberFunctionPointerType();
  case UTT_IsMemberObjectPointer:
    return T->isMemberDataPointerType();
  case UTT_IsEnum:
    return T->isEnumeralType();
  case UTT_IsUnion:
    return T->isUnionType();
  case UTT_IsClass:
    return T->isClassType() || T->isStructureType() || T->isInterfaceType();
  case UTT_IsFunction:
    return T->isFunctionType();
 
    // Type trait expressions which correspond to the convenient composition
    // predicates in C++0x [meta.unary.comp].
  case UTT_IsReference:
    return T->isReferenceType();
  case UTT_IsArithmetic:
    return T->isArithmeticType() && !T->isEnumeralType();
  case UTT_IsFundamental:
    return T->isFundamentalType();
  case UTT_IsObject:
    return T->isObjectType();
  case UTT_IsScalar:
    // Note: semantic analysis depends on Objective-C lifetime types to be
    // considered scalar types. However, such types do not actually behave
    // like scalar types at run time (since they may require retain/release
    // operations), so we report them as non-scalar.
    if (T->isObjCLifetimeType()) {
      switch (T.getObjCLifetime()) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
        return true;
 
      case Qualifiers::OCL_Strong:
      case Qualifiers::OCL_Weak:
      case Qualifiers::OCL_Autoreleasing:
        return false;
      }
    }
 
    return T->isScalarType();
  case UTT_IsCompound:
    return T->isCompoundType();
  case UTT_IsMemberPointer:
    return T->isMemberPointerType();
 
    // Type trait expressions which correspond to the type property predicates
    // in C++0x [meta.unary.prop].
  case UTT_IsConst:
    return T.isConstQualified();
  case UTT_IsVolatile:
    return T.isVolatileQualified();
  case UTT_IsTrivial:
    return T.isTrivialType(C);
  case UTT_IsTriviallyCopyable:
    return T.isTriviallyCopyableType(C);
  case UTT_IsStandardLayout:
    return T->isStandardLayoutType();
  case UTT_IsPOD:
    return T.isPODType(C);
  case UTT_IsLiteral:
    return T->isLiteralType(C);
  case UTT_IsEmpty:
    if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return !RD->isUnion() && RD->isEmpty();
    return false;
  case UTT_IsPolymorphic:
    if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return !RD->isUnion() && RD->isPolymorphic();
    return false;
  case UTT_IsAbstract:
    if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return !RD->isUnion() && RD->isAbstract();
    return false;
  case UTT_IsAggregate:
    // Report vector extensions and complex types as aggregates because they
    // support aggregate initialization. GCC mirrors this behavior for vectors
    // but not _Complex.
    return T->isAggregateType() || T->isVectorType() || T->isExtVectorType() ||
           T->isAnyComplexType();
  // __is_interface_class only returns true when CL is invoked in /CLR mode and
  // even then only when it is used with the 'interface struct ...' syntax
  // Clang doesn't support /CLR which makes this type trait moot.
  case UTT_IsInterfaceClass:
    return false;
  case UTT_IsFinal:
  case UTT_IsSealed:
    if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return RD->hasAttr<FinalAttr>();
    return false;
  case UTT_IsSigned:
    // Enum types should always return false.
    // Floating points should always return true.
    return T->isFloatingType() ||
           (T->isSignedIntegerType() && !T->isEnumeralType());
  case UTT_IsUnsigned:
    // Enum types should always return false.
    return T->isUnsignedIntegerType() && !T->isEnumeralType();
 
    // Type trait expressions which query classes regarding their construction,
    // destruction, and copying. Rather than being based directly on the
    // related type predicates in the standard, they are specified by both
    // GCC[1] and the Embarcadero C++ compiler[2], and Clang implements those
    // specifications.
    //
    //   1: http://gcc.gnu/.org/onlinedocs/gcc/Type-Traits.html
    //   2: http://docwiki.embarcadero.com/RADStudio/XE/en/Type_Trait_Functions_(C%2B%2B0x)_Index
    //
    // Note that these builtins do not behave as documented in g++: if a class
    // has both a trivial and a non-trivial special member of a particular kind,
    // they return false! For now, we emulate this behavior.
    // FIXME: This appears to be a g++ bug: more complex cases reveal that it
    // does not correctly compute triviality in the presence of multiple special
    // members of the same kind. Revisit this once the g++ bug is fixed.
  case UTT_HasTrivialDefaultConstructor:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If __is_pod (type) is true then the trait is true, else if type is
    //   a cv class or union type (or array thereof) with a trivial default
    //   constructor ([class.ctor]) then the trait is true, else it is false.
    if (T.isPODType(C))
      return true;
    if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
      return RD->hasTrivialDefaultConstructor() &&
             !RD->hasNonTrivialDefaultConstructor();
    return false;
  case UTT_HasTrivialMoveConstructor:
    //  This trait is implemented by MSVC 2012 and needed to parse the
    //  standard library headers. Specifically this is used as the logic
    //  behind std::is_trivially_move_constructible (20.9.4.3).
    if (T.isPODType(C))
      return true;
    if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
      return RD->hasTrivialMoveConstructor() && !RD->hasNonTrivialMoveConstructor();
    return false;
  case UTT_HasTrivialCopy:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If __is_pod (type) is true or type is a reference type then
    //   the trait is true, else if type is a cv class or union type
    //   with a trivial copy constructor ([class.copy]) then the trait
    //   is true, else it is false.
    if (T.isPODType(C) || T->isReferenceType())
      return true;
    if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return RD->hasTrivialCopyConstructor() &&
             !RD->hasNonTrivialCopyConstructor();
    return false;
  case UTT_HasTrivialMoveAssign:
    //  This trait is implemented by MSVC 2012 and needed to parse the
    //  standard library headers. Specifically it is used as the logic
    //  behind std::is_trivially_move_assignable (20.9.4.3)
    if (T.isPODType(C))
      return true;
    if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
      return RD->hasTrivialMoveAssignment() && !RD->hasNonTrivialMoveAssignment();
    return false;
  case UTT_HasTrivialAssign:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If type is const qualified or is a reference type then the
    //   trait is false. Otherwise if __is_pod (type) is true then the
    //   trait is true, else if type is a cv class or union type with
    //   a trivial copy assignment ([class.copy]) then the trait is
    //   true, else it is false.
    // Note: the const and reference restrictions are interesting,
    // given that const and reference members don't prevent a class
    // from having a trivial copy assignment operator (but do cause
    // errors if the copy assignment operator is actually used, q.v.
    // [class.copy]p12).
 
    if (T.isConstQualified())
      return false;
    if (T.isPODType(C))
      return true;
    if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      return RD->hasTrivialCopyAssignment() &&
             !RD->hasNonTrivialCopyAssignment();
    return false;
  case UTT_IsDestructible:
  case UTT_IsTriviallyDestructible:
  case UTT_IsNothrowDestructible:
    // C++14 [meta.unary.prop]:
    //   For reference types, is_destructible<T>::value is true.
    if (T->isReferenceType())
      return true;
 
    // Objective-C++ ARC: autorelease types don't require destruction.
    if (T->isObjCLifetimeType() &&
        T.getObjCLifetime() == Qualifiers::OCL_Autoreleasing)
      return true;
 
    // C++14 [meta.unary.prop]:
    //   For incomplete types and function types, is_destructible<T>::value is
    //   false.
    if (T->isIncompleteType() || T->isFunctionType())
      return false;
 
    // A type that requires destruction (via a non-trivial destructor or ARC
    // lifetime semantics) is not trivially-destructible.
    if (UTT == UTT_IsTriviallyDestructible && T.isDestructedType())
      return false;
 
    // C++14 [meta.unary.prop]:
    //   For object types and given U equal to remove_all_extents_t<T>, if the
    //   expression std::declval<U&>().~U() is well-formed when treated as an
    //   unevaluated operand (Clause 5), then is_destructible<T>::value is true
    if (auto *RD = C.getBaseElementType(T)->getAsCXXRecordDecl()) {
      CXXDestructorDecl *Destructor = Self.LookupDestructor(RD);
      if (!Destructor)
        return false;
      //  C++14 [dcl.fct.def.delete]p2:
      //    A program that refers to a deleted function implicitly or
      //    explicitly, other than to declare it, is ill-formed.
      if (Destructor->isDeleted())
        return false;
      if (C.getLangOpts().AccessControl && Destructor->getAccess() != AS_public)
        return false;
      if (UTT == UTT_IsNothrowDestructible) {
        auto *CPT = Destructor->getType()->castAs<FunctionProtoType>();
        CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
        if (!CPT || !CPT->isNothrow())
          return false;
      }
    }
    return true;
 
  case UTT_HasTrivialDestructor:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
    //   If __is_pod (type) is true or type is a reference type
    //   then the trait is true, else if type is a cv class or union
    //   type (or array thereof) with a trivial destructor
    //   ([class.dtor]) then the trait is true, else it is
    //   false.
    if (T.isPODType(C) || T->isReferenceType())
      return true;
 
    // Objective-C++ ARC: autorelease types don't require destruction.
    if (T->isObjCLifetimeType() &&
        T.getObjCLifetime() == Qualifiers::OCL_Autoreleasing)
      return true;
 
    if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl())
      return RD->hasTrivialDestructor();
    return false;
  // TODO: Propagate nothrowness for implicitly declared special members.
  case UTT_HasNothrowAssign:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If type is const qualified or is a reference type then the
    //   trait is false. Otherwise if __has_trivial_assign (type)
    //   is true then the trait is true, else if type is a cv class
    //   or union type with copy assignment operators that are known
    //   not to throw an exception then the trait is true, else it is
    //   false.
    if (C.getBaseElementType(T).isConstQualified())
      return false;
    if (T->isReferenceType())
      return false;
    if (T.isPODType(C) || T->isObjCLifetimeType())
      return true;
 
    if (const RecordType *RT = T->getAs<RecordType>())
      return HasNoThrowOperator(RT, OO_Equal, Self, KeyLoc, C,
                                &CXXRecordDecl::hasTrivialCopyAssignment,
                                &CXXRecordDecl::hasNonTrivialCopyAssignment,
                                &CXXMethodDecl::isCopyAssignmentOperator);
    return false;
  case UTT_HasNothrowMoveAssign:
    //  This trait is implemented by MSVC 2012 and needed to parse the
    //  standard library headers. Specifically this is used as the logic
    //  behind std::is_nothrow_move_assignable (20.9.4.3).
    if (T.isPODType(C))
      return true;
 
    if (const RecordType *RT = C.getBaseElementType(T)->getAs<RecordType>())
      return HasNoThrowOperator(RT, OO_Equal, Self, KeyLoc, C,
                                &CXXRecordDecl::hasTrivialMoveAssignment,
                                &CXXRecordDecl::hasNonTrivialMoveAssignment,
                                &CXXMethodDecl::isMoveAssignmentOperator);
    return false;
  case UTT_HasNothrowCopy:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If __has_trivial_copy (type) is true then the trait is true, else
    //   if type is a cv class or union type with copy constructors that are
    //   known not to throw an exception then the trait is true, else it is
    //   false.
    if (T.isPODType(C) || T->isReferenceType() || T->isObjCLifetimeType())
      return true;
    if (CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
      if (RD->hasTrivialCopyConstructor() &&
          !RD->hasNonTrivialCopyConstructor())
        return true;
 
      bool FoundConstructor = false;
      unsigned FoundTQs;
      for (const auto *ND : Self.LookupConstructors(RD)) {
        // A template constructor is never a copy constructor.
        // FIXME: However, it may actually be selected at the actual overload
        // resolution point.
        if (isa<FunctionTemplateDecl>(ND->getUnderlyingDecl()))
          continue;
        // UsingDecl itself is not a constructor
        if (isa<UsingDecl>(ND))
          continue;
        auto *Constructor = cast<CXXConstructorDecl>(ND->getUnderlyingDecl());
        if (Constructor->isCopyConstructor(FoundTQs)) {
          FoundConstructor = true;
          auto *CPT = Constructor->getType()->castAs<FunctionProtoType>();
          CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
          if (!CPT)
            return false;
          // TODO: check whether evaluating default arguments can throw.
          // For now, we'll be conservative and assume that they can throw.
          if (!CPT->isNothrow() || CPT->getNumParams() > 1)
            return false;
        }
      }
 
      return FoundConstructor;
    }
    return false;
  case UTT_HasNothrowConstructor:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
    //   If __has_trivial_constructor (type) is true then the trait is
    //   true, else if type is a cv class or union type (or array
    //   thereof) with a default constructor that is known not to
    //   throw an exception then the trait is true, else it is false.
    if (T.isPODType(C) || T->isObjCLifetimeType())
      return true;
    if (CXXRecordDecl *RD = C.getBaseElementType(T)->getAsCXXRecordDecl()) {
      if (RD->hasTrivialDefaultConstructor() &&
          !RD->hasNonTrivialDefaultConstructor())
        return true;
 
      bool FoundConstructor = false;
      for (const auto *ND : Self.LookupConstructors(RD)) {
        // FIXME: In C++0x, a constructor template can be a default constructor.
        if (isa<FunctionTemplateDecl>(ND->getUnderlyingDecl()))
          continue;
        // UsingDecl itself is not a constructor
        if (isa<UsingDecl>(ND))
          continue;
        auto *Constructor = cast<CXXConstructorDecl>(ND->getUnderlyingDecl());
        if (Constructor->isDefaultConstructor()) {
          FoundConstructor = true;
          auto *CPT = Constructor->getType()->castAs<FunctionProtoType>();
          CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
          if (!CPT)
            return false;
          // FIXME: check whether evaluating default arguments can throw.
          // For now, we'll be conservative and assume that they can throw.
          if (!CPT->isNothrow() || CPT->getNumParams() > 0)
            return false;
        }
      }
      return FoundConstructor;
    }
    return false;
  case UTT_HasVirtualDestructor:
    // http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html:
    //   If type is a class type with a virtual destructor ([class.dtor])
    //   then the trait is true, else it is false.
    if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
      if (CXXDestructorDecl *Destructor = Self.LookupDestructor(RD))
        return Destructor->isVirtual();
    return false;
 
    // These type trait expressions are modeled on the specifications for the
    // Embarcadero C++0x type trait functions:
    //   http://docwiki.embarcadero.com/RADStudio/XE/en/Type_Trait_Functions_(C%2B%2B0x)_Index
  case UTT_IsCompleteType:
    // http://docwiki.embarcadero.com/RADStudio/XE/en/Is_complete_type_(typename_T_):
    //   Returns True if and only if T is a complete type at the point of the
    //   function call.
    return !T->isIncompleteType();
  case UTT_HasUniqueObjectRepresentations:
    return C.hasUniqueObjectRepresentations(T);
  }
}
 
static bool EvaluateBinaryTypeTrait(Sema &Self, TypeTrait BTT, QualType LhsT,
                                    QualType RhsT, SourceLocation KeyLoc);
 
static bool evaluateTypeTrait(Sema &S, TypeTrait Kind, SourceLocation KWLoc,
                              ArrayRef<TypeSourceInfo *> Args,
                              SourceLocation RParenLoc) {
  if (Kind <= UTT_Last)
    return EvaluateUnaryTypeTrait(S, Kind, KWLoc, Args[0]->getType());
 
  // Evaluate BTT_ReferenceBindsToTemporary alongside the IsConstructible
  // traits to avoid duplication.
  if (Kind <= BTT_Last && Kind != BTT_ReferenceBindsToTemporary)
    return EvaluateBinaryTypeTrait(S, Kind, Args[0]->getType(),
                                   Args[1]->getType(), RParenLoc);
 
  switch (Kind) {
  case clang::BTT_ReferenceBindsToTemporary:
  case clang::TT_IsConstructible:
  case clang::TT_IsNothrowConstructible:
  case clang::TT_IsTriviallyConstructible: {
    // C++11 [meta.unary.prop]:
    //   is_trivially_constructible is defined as:
    //
    //     is_constructible<T, Args...>::value is true and the variable
    //     definition for is_constructible, as defined below, is known to call
    //     no operation that is not trivial.
    //
    //   The predicate condition for a template specialization
    //   is_constructible<T, Args...> shall be satisfied if and only if the
    //   following variable definition would be well-formed for some invented
    //   variable t:
    //
    //     T t(create<Args>()...);
    assert(!Args.empty());
 
    // Precondition: T and all types in the parameter pack Args shall be
    // complete types, (possibly cv-qualified) void, or arrays of
    // unknown bound.
    for (const auto *TSI : Args) {
      QualType ArgTy = TSI->getType();
      if (ArgTy->isVoidType() || ArgTy->isIncompleteArrayType())
        continue;
 
      if (S.RequireCompleteType(KWLoc, ArgTy,
          diag::err_incomplete_type_used_in_type_trait_expr))
        return false;
    }
 
    // Make sure the first argument is not incomplete nor a function type.
    QualType T = Args[0]->getType();
    if (T->isIncompleteType() || T->isFunctionType())
      return false;
 
    // Make sure the first argument is not an abstract type.
    CXXRecordDecl *RD = T->getAsCXXRecordDecl();
    if (RD && RD->isAbstract())
      return false;
 
    llvm::BumpPtrAllocator OpaqueExprAllocator;
    SmallVector<Expr *, 2> ArgExprs;
    ArgExprs.reserve(Args.size() - 1);
    for (unsigned I = 1, N = Args.size(); I != N; ++I) {
      QualType ArgTy = Args[I]->getType();
      if (ArgTy->isObjectType() || ArgTy->isFunctionType())
        ArgTy = S.Context.getRValueReferenceType(ArgTy);
      ArgExprs.push_back(
          new (OpaqueExprAllocator.Allocate<OpaqueValueExpr>())
              OpaqueValueExpr(Args[I]->getTypeLoc().getBeginLoc(),
                              ArgTy.getNonLValueExprType(S.Context),
                              Expr::getValueKindForType(ArgTy)));
    }
 
    // Perform the initialization in an unevaluated context within a SFINAE
    // trap at translation unit scope.
    EnterExpressionEvaluationContext Unevaluated(
        S, Sema::ExpressionEvaluationContext::Unevaluated);
    Sema::SFINAETrap SFINAE(S, /*AccessCheckingSFINAE=*/true);
    Sema::ContextRAII TUContext(S, S.Context.getTranslationUnitDecl());
    InitializedEntity To(
        InitializedEntity::InitializeTemporary(S.Context, Args[0]));
    InitializationKind InitKind(InitializationKind::CreateDirect(KWLoc, KWLoc,
                                                                 RParenLoc));
    InitializationSequence Init(S, To, InitKind, ArgExprs);
    if (Init.Failed())
      return false;
 
    ExprResult Result = Init.Perform(S, To, InitKind, ArgExprs);
    if (Result.isInvalid() || SFINAE.hasErrorOccurred())
      return false;
 
    if (Kind == clang::TT_IsConstructible)
      return true;
 
    if (Kind == clang::BTT_ReferenceBindsToTemporary) {
      if (!T->isReferenceType())
        return false;
 
      return !Init.isDirectReferenceBinding();
    }
 
    if (Kind == clang::TT_IsNothrowConstructible)
      return S.canThrow(Result.get()) == CT_Cannot;
 
    if (Kind == clang::TT_IsTriviallyConstructible) {
      // Under Objective-C ARC and Weak, if the destination has non-trivial
      // Objective-C lifetime, this is a non-trivial construction.
      if (T.getNonReferenceType().hasNonTrivialObjCLifetime())
        return false;
 
      // The initialization succeeded; now make sure there are no non-trivial
      // calls.
      return !Result.get()->hasNonTrivialCall(S.Context);
    }
 
    llvm_unreachable("unhandled type trait");
    return false;
  }
    default: llvm_unreachable("not a TT");
  }
 
  return false;
}
 
ExprResult Sema::BuildTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                                ArrayRef<TypeSourceInfo *> Args,
                                SourceLocation RParenLoc) {
  QualType ResultType = Context.getLogicalOperationType();
 
  if (Kind <= UTT_Last && !CheckUnaryTypeTraitTypeCompleteness(
                               *this, Kind, KWLoc, Args[0]->getType()))
    return ExprError();
 
  bool Dependent = false;
  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
    if (Args[I]->getType()->isDependentType()) {
      Dependent = true;
      break;
    }
  }
 
  bool Result = false;
  if (!Dependent)
    Result = evaluateTypeTrait(*this, Kind, KWLoc, Args, RParenLoc);
 
  return TypeTraitExpr::Create(Context, ResultType, KWLoc, Kind, Args,
                               RParenLoc, Result);
}
 
ExprResult Sema::ActOnTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                                ArrayRef<ParsedType> Args,
                                SourceLocation RParenLoc) {
  SmallVector<TypeSourceInfo *, 4> ConvertedArgs;
  ConvertedArgs.reserve(Args.size());
 
  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
    TypeSourceInfo *TInfo;
    QualType T = GetTypeFromParser(Args[I], &TInfo);
    if (!TInfo)