xref: /external/clang/lib/Sema/SemaExprCXX.cpp

//===--- SemaExprCXX.cpp - Semantic Analysis for Expressions --------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Implements semantic analysis for C++ expressions.
///
//===----------------------------------------------------------------------===//

#include "clang/Sema/SemaInternal.h"
#include "TypeLocBuilder.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/TypeLoc.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/TemplateDeduction.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;
using namespace sema;

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 this reason, we're currently only doing the C++03 version of this
  // code; the C++0x version has to wait until we get a proper spec.
  QualType SearchType;
  DeclContext *LookupCtx = 0;
  bool isDependent = false;
  bool LookInScope = false;

  // 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.
  if (ObjectTypePtr)
    SearchType = GetTypeFromParser(ObjectTypePtr);

  if (SS.isSet()) {
    NestedNameSpecifier *NNS = (NestedNameSpecifier *)SS.getScopeRep();

    bool AlreadySearched = false;
    bool LookAtPrefix = true;
    // C++ [basic.lookup.qual]p6:
    //   If a pseudo-destructor-name (5.2.4) contains a nested-name-specifier,
    //   the type-names are looked up as types in the scope designated by the
    //   nested-name-specifier. In a qualified-id of the form:
    //
    //     ::[opt] nested-name-specifier  ~ class-name
    //
    //   where the nested-name-specifier designates a namespace scope, and in
    //   a qualified-id of the form:
    //
    //     ::opt nested-name-specifier class-name ::  ~ class-name
    //
    //   the class-names are looked up as types in the scope designated by
    //   the nested-name-specifier.
    //
    // Here, we check the first case (completely) and determine whether the
    // code below is permitted to look at the prefix of the
    // nested-name-specifier.
    DeclContext *DC = computeDeclContext(SS, EnteringContext);
    if (DC && DC->isFileContext()) {
      AlreadySearched = true;
      LookupCtx = DC;
      isDependent = false;
    } else if (DC && isa<CXXRecordDecl>(DC))
      LookAtPrefix = false;

    // The second case from the C++03 rules quoted further above.
    NestedNameSpecifier *Prefix = 0;
    if (AlreadySearched) {
      // Nothing left to do.
    } else if (LookAtPrefix && (Prefix = NNS->getPrefix())) {
      CXXScopeSpec PrefixSS;
      PrefixSS.Adopt(NestedNameSpecifierLoc(Prefix, SS.location_data()));
      LookupCtx = computeDeclContext(PrefixSS, EnteringContext);
      isDependent = isDependentScopeSpecifier(PrefixSS);
    } else if (ObjectTypePtr) {
      LookupCtx = computeDeclContext(SearchType);
      isDependent = SearchType->isDependentType();
    } else {
      LookupCtx = computeDeclContext(SS, EnteringContext);
      isDependent = LookupCtx && LookupCtx->isDependentContext();
    }

    LookInScope = false;
  } else if (ObjectTypePtr) {
    // 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 (possibly
    //   cv-qualified) T.
    LookupCtx = computeDeclContext(SearchType);
    isDependent = SearchType->isDependentType();
    assert((isDependent || !SearchType->isIncompleteType()) &&
           "Caller should have completed object type");

    LookInScope = true;
  } else {
    // Perform lookup into the current scope (only).
    LookInScope = true;
  }

  TypeDecl *NonMatchingTypeDecl = 0;
  LookupResult Found(*this, &II, NameLoc, LookupOrdinaryName);
  for (unsigned Step = 0; Step != 2; ++Step) {
    // Look for the name first in the computed lookup context (if we
    // have one) and, if that fails to find a match, in the scope (if
    // we're allowed to look there).
    Found.clear();
    if (Step == 0 && LookupCtx)
      LookupQualifiedName(Found, LookupCtx);
    else if (Step == 1 && LookInScope && S)
      LookupName(Found, S);
    else
      continue;

    // FIXME: Should we be suppressing ambiguities here?
    if (Found.isAmbiguous())
      return ParsedType();

    if (TypeDecl *Type = Found.getAsSingle<TypeDecl>()) {
      QualType T = Context.getTypeDeclType(Type);

      if (SearchType.isNull() || SearchType->isDependentType() ||
          Context.hasSameUnqualifiedType(T, SearchType)) {
        // We found our type!

        return ParsedType::make(T);
      }

      if (!SearchType.isNull())
        NonMatchingTypeDecl = Type;
    }

    // If the name that we found is a class template name, and it is
    // the same name as the template name in the last part of the
    // nested-name-specifier (if present) or the object type, then
    // this is the destructor for that class.
    // FIXME: This is a workaround until we get real drafting for core
    // issue 399, for which there isn't even an obvious direction.
    if (ClassTemplateDecl *Template = Found.getAsSingle<ClassTemplateDecl>()) {
      QualType MemberOfType;
      if (SS.isSet()) {
        if (DeclContext *Ctx = computeDeclContext(SS, EnteringContext)) {
          // Figure out the type of the context, if it has one.
          if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx))
            MemberOfType = Context.getTypeDeclType(Record);
        }
      }
      if (MemberOfType.isNull())
        MemberOfType = SearchType;

      if (MemberOfType.isNull())
        continue;

      // We're referring into a class template specialization. If the
      // class template we found is the same as the template being
      // specialized, we found what we are looking for.
      if (const RecordType *Record = MemberOfType->getAs<RecordType>()) {
        if (ClassTemplateSpecializationDecl *Spec
              = dyn_cast<ClassTemplateSpecializationDecl>(Record->getDecl())) {
          if (Spec->getSpecializedTemplate()->getCanonicalDecl() ==
                Template->getCanonicalDecl())
            return ParsedType::make(MemberOfType);
        }

        continue;
      }

      // We're referring to an unresolved class template
      // specialization. Determine whether we class template we found
      // is the same as the template being specialized or, if we don't
      // know which template is being specialized, that it at least
      // has the same name.
      if (const TemplateSpecializationType *SpecType
            = MemberOfType->getAs<TemplateSpecializationType>()) {
        TemplateName SpecName = SpecType->getTemplateName();

        // The class template we found is the same template being
        // specialized.
        if (TemplateDecl *SpecTemplate = SpecName.getAsTemplateDecl()) {
          if (SpecTemplate->getCanonicalDecl() == Template->getCanonicalDecl())
            return ParsedType::make(MemberOfType);

          continue;
        }

        // The class template we found has the same name as the
        // (dependent) template name being specialized.
        if (DependentTemplateName *DepTemplate
                                    = SpecName.getAsDependentTemplateName()) {
          if (DepTemplate->isIdentifier() &&
              DepTemplate->getIdentifier() == Template->getIdentifier())
            return ParsedType::make(MemberOfType);

          continue;
        }
      }
    }
  }

  if (isDependent) {
    // We didn't find our type, but that's okay: 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);
  }

  if (NonMatchingTypeDecl) {
    QualType T = Context.getTypeDeclType(NonMatchingTypeDecl);
    Diag(NameLoc, diag::err_destructor_expr_type_mismatch)
      << T << SearchType;
    Diag(NonMatchingTypeDecl->getLocation(), diag::note_destructor_type_here)
      << T;
  } else if (ObjectTypePtr)
    Diag(NameLoc, diag::err_ident_in_dtor_not_a_type)
      << &II;
  else
    Diag(NameLoc, diag::err_destructor_class_name);

  return ParsedType();
}

ParsedType Sema::getDestructorType(const DeclSpec& DS, ParsedType ObjectType) {
    if (DS.getTypeSpecType() == DeclSpec::TST_error || !ObjectType)
      return ParsedType();
    assert(DS.getTypeSpecType() == DeclSpec::TST_decltype
           && "only get destructor types from declspecs");
    QualType T = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
    QualType SearchType = GetTypeFromParser(ObjectType);
    if (SearchType->isDependentType() || Context.hasSameUnqualifiedType(SearchType, T)) {
      return ParsedType::make(T);
    }

    Diag(DS.getTypeSpecTypeLoc(), diag::err_destructor_expr_type_mismatch)
      << T << SearchType;
    return ParsedType();
}

/// \brief 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();

  return Owned(new (Context) CXXTypeidExpr(TypeInfoType.withConst(),
                                           Operand,
                                           SourceRange(TypeidLoc, RParenLoc)));
}

/// \brief Build a C++ typeid expression with an expression operand.
ExprResult Sema::BuildCXXTypeId(QualType TypeInfoType,
                                SourceLocation TypeidLoc,
                                Expr *E,
                                SourceLocation RParenLoc) {
  if (E && !E->isTypeDependent()) {
    if (E->getType()->isPlaceholderType()) {
      ExprResult result = CheckPlaceholderExpr(E);
      if (result.isInvalid()) return ExprError();
      E = result.take();
    }

    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()) {
        // The subexpression is potentially evaluated; switch the context
        // and recheck the subexpression.
        ExprResult Result = TransformToPotentiallyEvaluated(E);
        if (Result.isInvalid()) return ExprError();
        E = Result.take();

        // We require a vtable to query the type at run time.
        MarkVTableUsed(TypeidLoc, RecordD);
      }
    }

    // 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()).take();
    }
  }

  return Owned(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) {
  // 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.MicrosoftMode) {
      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 = 0;
    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.
  return BuildCXXTypeId(TypeInfoType, OpLoc, (Expr*)TyOrExpr, RParenLoc);
}

/// \brief Build a Microsoft __uuidof expression with a type operand.
ExprResult Sema::BuildCXXUuidof(QualType TypeInfoType,
                                SourceLocation TypeidLoc,
                                TypeSourceInfo *Operand,
                                SourceLocation RParenLoc) {
  if (!Operand->getType()->isDependentType()) {
    if (!CXXUuidofExpr::GetUuidAttrOfType(Operand->getType()))
      return ExprError(Diag(TypeidLoc, diag::err_uuidof_without_guid));
  }

  // FIXME: add __uuidof semantic analysis for type operand.
  return Owned(new (Context) CXXUuidofExpr(TypeInfoType.withConst(),
                                           Operand,
                                           SourceRange(TypeidLoc, RParenLoc)));
}

/// \brief Build a Microsoft __uuidof expression with an expression operand.
ExprResult Sema::BuildCXXUuidof(QualType TypeInfoType,
                                SourceLocation TypeidLoc,
                                Expr *E,
                                SourceLocation RParenLoc) {
  if (!E->getType()->isDependentType()) {
    if (!CXXUuidofExpr::GetUuidAttrOfType(E->getType()) &&
        !E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull))
      return ExprError(Diag(TypeidLoc, diag::err_uuidof_without_guid));
  }
  // FIXME: add __uuidof semantic analysis for type operand.
  return Owned(new (Context) CXXUuidofExpr(TypeInfoType.withConst(),
                                           E,
                                           SourceRange(TypeidLoc, RParenLoc)));
}

/// ActOnCXXUuidof - Parse __uuidof( type-id ) or __uuidof (expression);
ExprResult
Sema::ActOnCXXUuidof(SourceLocation OpLoc, SourceLocation LParenLoc,
                     bool isType, void *TyOrExpr, SourceLocation RParenLoc) {
  // If MSVCGuidDecl has not been cached, do the lookup.
  if (!MSVCGuidDecl) {
    IdentifierInfo *GuidII = &PP.getIdentifierTable().get("_GUID");
    LookupResult R(*this, GuidII, SourceLocation(), LookupTagName);
    LookupQualifiedName(R, Context.getTranslationUnitDecl());
    MSVCGuidDecl = R.getAsSingle<RecordDecl>();
    if (!MSVCGuidDecl)
      return ExprError(Diag(OpLoc, diag::err_need_header_before_ms_uuidof));
  }

  QualType GuidType = Context.getTypeDeclType(MSVCGuidDecl);

  if (isType) {
    // The operand is a type; handle it as such.
    TypeSourceInfo *TInfo = 0;
    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 Owned(new (Context) CXXBoolLiteralExpr(Kind == tok::kw_true,
                                                Context.BoolTy, OpLoc));
}

/// ActOnCXXNullPtrLiteral - Parse 'nullptr'.
ExprResult
Sema::ActOnCXXNullPtrLiteral(SourceLocation Loc) {
  return Owned(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))
    Diag(OpLoc, diag::err_exceptions_disabled) << "throw";

  if (Ex && !Ex->isTypeDependent()) {
    ExprResult ExRes = CheckCXXThrowOperand(OpLoc, Ex, IsThrownVarInScope);
    if (ExRes.isInvalid())
      return ExprError();
    Ex = ExRes.take();
  }

  return Owned(new (Context) CXXThrowExpr(Ex, Context.VoidTy, OpLoc,
                                          IsThrownVarInScope));
}

/// CheckCXXThrowOperand - Validate the operand of a throw.
ExprResult Sema::CheckCXXThrowOperand(SourceLocation ThrowLoc, Expr *E,
                                      bool IsThrownVarInScope) {
  // C++ [except.throw]p3:
  //   A throw-expression initializes a temporary object, called the exception
  //   object, the type of which is determined by removing any top-level
  //   cv-qualifiers from the static type of the operand of throw and adjusting
  //   the type from "array of T" or "function returning T" to "pointer to T"
  //   or "pointer to function returning T", [...]
  if (E->getType().hasQualifiers())
    E = ImpCastExprToType(E, E->getType().getUnqualifiedType(), CK_NoOp,
                          E->getValueKind()).take();

  ExprResult Res = DefaultFunctionArrayConversion(E);
  if (Res.isInvalid())
    return ExprError();
  E = Res.take();

  //   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 = E->getType();
  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 ExprError();

    if (RequireNonAbstractType(ThrowLoc, E->getType(),
                               diag::err_throw_abstract_type, E))
      return ExprError();
  }

  // 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
  const VarDecl *NRVOVariable = 0;
  if (IsThrownVarInScope)
    NRVOVariable = getCopyElisionCandidate(QualType(), E, false);

  InitializedEntity Entity =
      InitializedEntity::InitializeException(ThrowLoc, E->getType(),
                                             /*NRVO=*/NRVOVariable != 0);
  Res = PerformMoveOrCopyInitialization(Entity, NRVOVariable,
                                        QualType(), E,
                                        IsThrownVarInScope);
  if (Res.isInvalid())
    return ExprError();
  E = Res.take();

  // If the exception has class type, we need additional handling.
  const RecordType *RecordTy = Ty->getAs<RecordType>();
  if (!RecordTy)
    return Owned(E);
  CXXRecordDecl *RD = cast<CXXRecordDecl>(RecordTy->getDecl());

  // 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 Owned(E);

  // If the class has a destructor, we must be able to call it.
  if (RD->hasIrrelevantDestructor())
    return Owned(E);

  CXXDestructorDecl *Destructor = LookupDestructor(RD);
  if (!Destructor)
    return Owned(E);

  MarkFunctionReferenced(E->getExprLoc(), Destructor);
  CheckDestructorAccess(E->getExprLoc(), Destructor,
                        PDiag(diag::err_access_dtor_exception) << Ty);
  DiagnoseUseOfDecl(Destructor, E->getExprLoc());
  return Owned(E);
}

QualType Sema::getCurrentThisType() {
  DeclContext *DC = getFunctionLevelDeclContext();
  QualType ThisTy = CXXThisTypeOverride;
  if (CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(DC)) {
    if (method && method->isInstance())
      ThisTy = method->getThisType(Context);
  }

  return ThisTy;
}

Sema::CXXThisScopeRAII::CXXThisScopeRAII(Sema &S,
                                         Decl *ContextDecl,
                                         unsigned CXXThisTypeQuals,
                                         bool Enabled)
  : S(S), OldCXXThisTypeOverride(S.CXXThisTypeOverride), Enabled(false)
{
  if (!Enabled || !ContextDecl)
    return;

  CXXRecordDecl *Record = 0;
  if (ClassTemplateDecl *Template = dyn_cast<ClassTemplateDecl>(ContextDecl))
    Record = Template->getTemplatedDecl();
  else
    Record = cast<CXXRecordDecl>(ContextDecl);

  S.CXXThisTypeOverride
    = S.Context.getPointerType(
        S.Context.getRecordType(Record).withCVRQualifiers(CXXThisTypeQuals));

  this->Enabled = true;
}


Sema::CXXThisScopeRAII::~CXXThisScopeRAII() {
  if (Enabled) {
    S.CXXThisTypeOverride = OldCXXThisTypeOverride;
  }
}

void Sema::CheckCXXThisCapture(SourceLocation Loc, bool Explicit) {
  // We don't need to capture this in an unevaluated context.
  if (ExprEvalContexts.back().Context == Unevaluated && !Explicit)
    return;

  // Otherwise, check that we can capture 'this'.
  unsigned NumClosures = 0;
  for (unsigned idx = FunctionScopes.size() - 1; 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.
        break;
      }

      if (CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByref ||
          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_LambdaByval ||
          CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_Block ||
          Explicit) {
        // This closure can capture 'this'; continue looking upwards.
        NumClosures++;
        Explicit = false;
        continue;
      }
      // This context can't implicitly capture 'this'; fail out.
      Diag(Loc, diag::err_this_capture) << Explicit;
      return;
    }
    break;
  }

  // Mark that we're implicitly capturing 'this' in all the scopes we skipped.
  // FIXME: We need to delay this marking in PotentiallyPotentiallyEvaluated
  // contexts.
  for (unsigned idx = FunctionScopes.size() - 1;
       NumClosures; --idx, --NumClosures) {
    CapturingScopeInfo *CSI = cast<CapturingScopeInfo>(FunctionScopes[idx]);
    Expr *ThisExpr = 0;
    QualType ThisTy = getCurrentThisType();
    if (LambdaScopeInfo *LSI = dyn_cast<LambdaScopeInfo>(CSI)) {
      // For lambda expressions, build a field and an initializing expression.
      CXXRecordDecl *Lambda = LSI->Lambda;
      FieldDecl *Field
        = FieldDecl::Create(Context, Lambda, Loc, Loc, 0, ThisTy,
                            Context.getTrivialTypeSourceInfo(ThisTy, Loc),
                            0, false, ICIS_NoInit);
      Field->setImplicit(true);
      Field->setAccess(AS_private);
      Lambda->addDecl(Field);
      ThisExpr = new (Context) CXXThisExpr(Loc, ThisTy, /*isImplicit=*/true);
    }
    bool isNested = NumClosures > 1;
    CSI->addThisCapture(isNested, Loc, ThisTy, ThisExpr);
  }
}

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);

  CheckCXXThisCapture(Loc);
  return Owned(new (Context) CXXThisExpr(Loc, ThisTy, /*isImplicit=*/false));
}

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();
}

ExprResult
Sema::ActOnCXXTypeConstructExpr(ParsedType TypeRep,
                                SourceLocation LParenLoc,
                                MultiExprArg exprs,
                                SourceLocation RParenLoc) {
  if (!TypeRep)
    return ExprError();

  TypeSourceInfo *TInfo;
  QualType Ty = GetTypeFromParser(TypeRep, &TInfo);
  if (!TInfo)
    TInfo = Context.getTrivialTypeSourceInfo(Ty, SourceLocation());

  return BuildCXXTypeConstructExpr(TInfo, LParenLoc, exprs, RParenLoc);
}

/// ActOnCXXTypeConstructExpr - 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::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
                                SourceLocation LParenLoc,
                                MultiExprArg exprs,
                                SourceLocation RParenLoc) {
  QualType Ty = TInfo->getType();
  SourceLocation TyBeginLoc = TInfo->getTypeLoc().getBeginLoc();

  if (Ty->isDependentType() || CallExpr::hasAnyTypeDependentArguments(exprs)) {
    return Owned(CXXUnresolvedConstructExpr::Create(Context, TInfo,
                                                    LParenLoc,
                                                    exprs,
                                                    RParenLoc));
  }

  unsigned NumExprs = exprs.size();
  Expr **Exprs = exprs.data();

  bool ListInitialization = LParenLoc.isInvalid();
  assert((!ListInitialization || (NumExprs == 1 && isa<InitListExpr>(Exprs[0])))
         && "List initialization must have initializer list as expression.");
  SourceRange FullRange = SourceRange(TyBeginLoc,
      ListInitialization ? Exprs[0]->getSourceRange().getEnd() : RParenLoc);

  // C++ [expr.type.conv]p1:
  // If the expression list is a single expression, the type conversion
  // expression is equivalent (in definedness, and if defined in meaning) to the
  // corresponding cast expression.
  if (NumExprs == 1 && !ListInitialization) {
    Expr *Arg = Exprs[0];
    return BuildCXXFunctionalCastExpr(TInfo, LParenLoc, Arg, RParenLoc);
  }

  QualType ElemTy = Ty;
  if (Ty->isArrayType()) {
    if (!ListInitialization)
      return ExprError(Diag(TyBeginLoc,
                            diag::err_value_init_for_array_type) << FullRange);
    ElemTy = Context.getBaseElementType(Ty);
  }

  if (!Ty->isVoidType() &&
      RequireCompleteType(TyBeginLoc, ElemTy,
                          diag::err_invalid_incomplete_type_use, FullRange))
    return ExprError();

  if (RequireNonAbstractType(TyBeginLoc, Ty,
                             diag::err_allocation_of_abstract_type))
    return ExprError();

  InitializedEntity Entity = InitializedEntity::InitializeTemporary(TInfo);
  InitializationKind Kind
    = NumExprs ? ListInitialization
                    ? InitializationKind::CreateDirectList(TyBeginLoc)
                    : InitializationKind::CreateDirect(TyBeginLoc,
                                                       LParenLoc, RParenLoc)
               : InitializationKind::CreateValue(TyBeginLoc,
                                                 LParenLoc, RParenLoc);
  InitializationSequence InitSeq(*this, Entity, Kind, Exprs, NumExprs);
  ExprResult Result = InitSeq.Perform(*this, Entity, Kind, exprs);

  if (!Result.isInvalid() && ListInitialization &&
      isa<InitListExpr>(Result.get())) {
    // If the list-initialization doesn't involve a constructor call, we'll get
    // the initializer-list (with corrected type) back, but that's not what we
    // want, since it will be treated as an initializer list in further
    // processing. Explicitly insert a cast here.
    InitListExpr *List = cast<InitListExpr>(Result.take());
    Result = Owned(CXXFunctionalCastExpr::Create(Context, List->getType(),
                                    Expr::getValueKindForType(TInfo->getType()),
                                                 TInfo, TyBeginLoc, CK_NoOp,
                                                 List, /*Path=*/0, RParenLoc));
  }

  // FIXME: Improve AST representation?
  return Result;
}

/// doesUsualArrayDeleteWantSize - Answers whether the usual
/// operator delete[] for the given type has a size_t parameter.
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;

  LookupResult::Filter filter = ops.makeFilter();
  while (filter.hasNext()) {
    NamedDecl *del = filter.next()->getUnderlyingDecl();

    // C++0x [basic.stc.dynamic.deallocation]p2:
    //   A template instance is never a usual deallocation function,
    //   regardless of its signature.
    if (isa<FunctionTemplateDecl>(del)) {
      filter.erase();
      continue;
    }

    // C++0x [basic.stc.dynamic.deallocation]p2:
    //   If class T does not declare [an operator delete[] with one
    //   parameter] but does declare a member deallocation function
    //   named operator delete[] with exactly two parameters, the
    //   second of which has type std::size_t, then this function
    //   is a usual deallocation function.
    if (!cast<CXXMethodDecl>(del)->isUsualDeallocationFunction()) {
      filter.erase();
      continue;
    }
  }
  filter.done();

  if (!ops.isSingleResult()) return false;

  const FunctionDecl *del = cast<FunctionDecl>(ops.getFoundDecl());
  return (del->getNumParams() == 2);
}

/// \brief 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) {
  bool TypeContainsAuto = D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto;

  Expr *ArraySize = 0;
  // 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 (TypeContainsAuto)
      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)
      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()) {
          Array.NumElts
            = VerifyIntegerConstantExpression(NumElts, 0,
                                              diag::err_new_array_nonconst)
                .take();
          if (!Array.NumElts)
            return ExprError();
        }
      }
    }
  }

  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, /*Scope=*/0);
  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.getLocEnd()), UseGlobal,
                     PlacementLParen,
                     PlacementArgs,
                     PlacementRParen,
                     TypeIdParens,
                     AllocType,
                     TInfo,
                     ArraySize,
                     DirectInitRange,
                     Initializer,
                     TypeContainsAuto);
}

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;
}

ExprResult
Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
                  SourceLocation PlacementLParen,
                  MultiExprArg PlacementArgs,
                  SourceLocation PlacementRParen,
                  SourceRange TypeIdParens,
                  QualType AllocType,
                  TypeSourceInfo *AllocTypeInfo,
                  Expr *ArraySize,
                  SourceRange DirectInitRange,
                  Expr *Initializer,
                  bool TypeMayContainAuto) {
  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();
  }

  // Determine whether we've already built the initializer.
  bool HaveCompleteInit = false;
  if (Initializer && isa<CXXConstructExpr>(Initializer) &&
      !isa<CXXTemporaryObjectExpr>(Initializer))
    HaveCompleteInit = true;
  else if (Initializer && isa<ImplicitValueInitExpr>(Initializer))
    HaveCompleteInit = true;

  // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
  AutoType *AT = 0;
  if (TypeMayContainAuto &&
      (AT = AllocType->getContainedAutoType()) && !AT->isDeduced()) {
    if (initStyle == CXXNewExpr::NoInit || NumInits == 0)
      return ExprError(Diag(StartLoc, diag::err_auto_new_requires_ctor_arg)
                       << AllocType << TypeRange);
    if (initStyle == CXXNewExpr::ListInit)
      return ExprError(Diag(Inits[0]->getLocStart(),
                            diag::err_auto_new_requires_parens)
                       << AllocType << TypeRange);
    if (NumInits > 1) {
      Expr *FirstBad = Inits[1];
      return ExprError(Diag(FirstBad->getLocStart(),
                            diag::err_auto_new_ctor_multiple_expressions)
                       << AllocType << TypeRange);
    }
    Expr *Deduce = Inits[0];
    TypeSourceInfo *DeducedType = 0;
    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)
      return ExprError();

    AllocTypeInfo = DeducedType;
    AllocType = AllocTypeInfo->getType();
  }

  // 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();

  if (initStyle == CXXNewExpr::ListInit && isStdInitializerList(AllocType, 0)) {
    Diag(AllocTypeInfo->getTypeLoc().getBeginLoc(),
         diag::warn_dangling_std_initializer_list)
        << /*at end of FE*/0 << Inits[0]->getSourceRange();
  }

  // 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);

  // 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.
  if (ArraySize && !ArraySize->isTypeDependent()) {
    class SizeConvertDiagnoser : public ICEConvertDiagnoser {
      Expr *ArraySize;

    public:
      SizeConvertDiagnoser(Expr *ArraySize)
        : ICEConvertDiagnoser(false, false), ArraySize(ArraySize) { }

      virtual DiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
                                               QualType T) {
        return S.Diag(Loc, diag::err_array_size_not_integral)
                 << S.getLangOpts().CPlusPlus11 << T;
      }

      virtual DiagnosticBuilder diagnoseIncomplete(Sema &S, SourceLocation Loc,
                                                   QualType T) {
        return S.Diag(Loc, diag::err_array_size_incomplete_type)
                 << T << ArraySize->getSourceRange();
      }

      virtual DiagnosticBuilder diagnoseExplicitConv(Sema &S,
                                                     SourceLocation Loc,
                                                     QualType T,
                                                     QualType ConvTy) {
        return S.Diag(Loc, diag::err_array_size_explicit_conversion) << T << ConvTy;
      }

      virtual DiagnosticBuilder noteExplicitConv(Sema &S,
                                                 CXXConversionDecl *Conv,
                                                 QualType ConvTy) {
        return S.Diag(Conv->getLocation(), diag::note_array_size_conversion)
                 << ConvTy->isEnumeralType() << ConvTy;
      }

      virtual DiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc,
                                                  QualType T) {
        return S.Diag(Loc, diag::err_array_size_ambiguous_conversion) << T;
      }

      virtual DiagnosticBuilder noteAmbiguous(Sema &S, CXXConversionDecl *Conv,
                                              QualType ConvTy) {
        return S.Diag(Conv->getLocation(), diag::note_array_size_conversion)
                 << ConvTy->isEnumeralType() << ConvTy;
      }

      virtual DiagnosticBuilder diagnoseConversion(Sema &S, SourceLocation Loc,
                                                   QualType T,
                                                   QualType ConvTy) {
        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);

    ExprResult ConvertedSize
      = ConvertToIntegralOrEnumerationType(StartLoc, ArraySize, SizeDiagnoser,
                                           /*AllowScopedEnumerations*/ false);
    if (ConvertedSize.isInvalid())
      return ExprError();

    ArraySize = ConvertedSize.take();
    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. Otherwise, if it's not a constant, we must have an unparenthesized
    // array type.
    //
    // Note: such a construct has well-defined semantics in C++11: it throws
    // std::bad_array_new_length.
    if (!ArraySize->isValueDependent()) {
      llvm::APSInt Value;
      // We've already performed any required implicit conversion to integer or
      // unscoped enumeration type.
      if (ArraySize->isIntegerConstantExpr(Value, Context)) {
        if (Value < llvm::APSInt(
                        llvm::APInt::getNullValue(Value.getBitWidth()),
                                 Value.isUnsigned())) {
          if (getLangOpts().CPlusPlus11)
            Diag(ArraySize->getLocStart(),
                 diag::warn_typecheck_negative_array_new_size)
              << ArraySize->getSourceRange();
          else
            return ExprError(Diag(ArraySize->getLocStart(),
                                  diag::err_typecheck_negative_array_size)
                             << ArraySize->getSourceRange());
        } else if (!AllocType->isDependentType()) {
          unsigned ActiveSizeBits =
            ConstantArrayType::getNumAddressingBits(Context, AllocType, Value);
          if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context)) {
            if (getLangOpts().CPlusPlus11)
              Diag(ArraySize->getLocStart(),
                   diag::warn_array_new_too_large)
                << Value.toString(10)
                << ArraySize->getSourceRange();
            else
              return ExprError(Diag(ArraySize->getLocStart(),
                                    diag::err_array_too_large)
                               << Value.toString(10)
                               << ArraySize->getSourceRange());
          }
        }
      } else if (TypeIdParens.isValid()) {
        // Can't have dynamic array size when the type-id is in parentheses.
        Diag(ArraySize->getLocStart(), 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 = 0;
  FunctionDecl *OperatorDelete = 0;
  Expr **PlaceArgs = PlacementArgs.data();
  unsigned NumPlaceArgs = PlacementArgs.size();

  if (!AllocType->isDependentType() &&
      !Expr::hasAnyTypeDependentArguments(
        llvm::makeArrayRef(PlaceArgs, NumPlaceArgs)) &&
      FindAllocationFunctions(StartLoc,
                              SourceRange(PlacementLParen, PlacementRParen),
                              UseGlobal, AllocType, ArraySize, PlaceArgs,
                              NumPlaceArgs, 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) {
    // Add default arguments, if any.
    const FunctionProtoType *Proto =
      OperatorNew->getType()->getAs<FunctionProtoType>();
    VariadicCallType CallType =
      Proto->isVariadic() ? VariadicFunction : VariadicDoesNotApply;

    if (GatherArgumentsForCall(PlacementLParen, OperatorNew,
                               Proto, 1, PlaceArgs, NumPlaceArgs,
                               AllPlaceArgs, CallType))
      return ExprError();

    NumPlaceArgs = AllPlaceArgs.size();
    if (NumPlaceArgs > 0)
      PlaceArgs = &AllPlaceArgs[0];

    DiagnoseSentinelCalls(OperatorNew, PlacementLParen,
                          PlaceArgs, NumPlaceArgs);

    // FIXME: Missing call to CheckFunctionCall or equivalent
  }

  // Warn if the type is over-aligned and is being allocated by global operator
  // new.
  if (NumPlaceArgs == 0 && OperatorNew &&
      (OperatorNew->isImplicit() ||
       getSourceManager().isInSystemHeader(OperatorNew->getLocStart()))) {
    if (unsigned Align = Context.getPreferredTypeAlign(AllocType.getTypePtr())){
      unsigned SuitableAlign = Context.getTargetInfo().getSuitableAlign();
      if (Align > SuitableAlign)
        Diag(StartLoc, diag::warn_overaligned_type)
            << AllocType
            << unsigned(Align / Context.getCharWidth())
            << unsigned(SuitableAlign / Context.getCharWidth());
    }
  }

  QualType InitType = AllocType;
  // 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 (ResultType->isArrayType() || ArraySize) {
    if (!isLegalArrayNewInitializer(initStyle, Initializer)) {
      SourceRange InitRange(Inits[0]->getLocStart(),
                            Inits[NumInits - 1]->getLocEnd());
      Diag(StartLoc, diag::err_new_array_init_args) << InitRange;
      return ExprError();
    }
    if (InitListExpr *ILE = dyn_cast_or_null<InitListExpr>(Initializer)) {
      // We do the initialization typechecking against the array type
      // corresponding to the number of initializers + 1 (to also check
      // default-initialization).
      unsigned NumElements = ILE->getNumInits() + 1;
      InitType = Context.getConstantArrayType(AllocType,
          llvm::APInt(Context.getTypeSize(Context.getSizeType()), NumElements),
                                              ArrayType::Normal, 0);
    }
  }

  // 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)) &&
      !HaveCompleteInit) {
    // 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())
              : InitializationKind::CreateDirect(TypeRange.getBegin(),
                                                 DirectInitRange.getBegin(),
                                                 DirectInitRange.getEnd());

    InitializedEntity Entity
      = InitializedEntity::InitializeNew(StartLoc, InitType);
    InitializationSequence InitSeq(*this, Entity, Kind, 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.
    if (CXXBindTemporaryExpr *Binder =
            dyn_cast_or_null<CXXBindTemporaryExpr>(FullInit.get()))
      FullInit = Owned(Binder->getSubExpr());

    Initializer = FullInit.take();
  }

  // Mark the new and delete operators as referenced.
  if (OperatorNew) {
    DiagnoseUseOfDecl(OperatorNew, StartLoc);
    MarkFunctionReferenced(StartLoc, OperatorNew);
  }
  if (OperatorDelete) {
    DiagnoseUseOfDecl(OperatorDelete, StartLoc);
    MarkFunctionReferenced(StartLoc, OperatorDelete);
  }

  // C++0x [expr.new]p17:
  //   If the new expression creates an array of objects of class type,
  //   access and ambiguity control are done for the destructor.
  QualType BaseAllocType = Context.getBaseElementType(AllocType);
  if (ArraySize && !BaseAllocType->isDependentType()) {
    if (const RecordType *BaseRecordType = BaseAllocType->getAs<RecordType>()) {
      if (CXXDestructorDecl *dtor = LookupDestructor(
              cast<CXXRecordDecl>(BaseRecordType->getDecl()))) {
        MarkFunctionReferenced(StartLoc, dtor);
        CheckDestructorAccess(StartLoc, dtor,
                              PDiag(diag::err_access_dtor)
                                << BaseAllocType);
        DiagnoseUseOfDecl(dtor, StartLoc);
      }
    }
  }

  return Owned(new (Context) CXXNewExpr(Context, UseGlobal, OperatorNew,
                                        OperatorDelete,
                                        UsualArrayDeleteWantsSize,
                                   llvm::makeArrayRef(PlaceArgs, NumPlaceArgs),
                                        TypeIdParens,
                                        ArraySize, initStyle, Initializer,
                                        ResultType, AllocTypeInfo,
                                        Range, DirectInitRange));
}

/// \brief 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() &&
           RequireCompleteType(Loc, AllocType, diag::err_new_incomplete_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 (unsigned AddressSpace = AllocType.getAddressSpace())
    return Diag(Loc, diag::err_address_space_qualified_new)
      << AllocType.getUnqualifiedType() << AddressSpace;
  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;
}

/// \brief Determine whether the given function is a non-placement
/// deallocation function.
static bool isNonPlacementDeallocationFunction(FunctionDecl *FD) {
  if (FD->isInvalidDecl())
    return false;

  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(FD))
    return Method->isUsualDeallocationFunction();

  return ((FD->getOverloadedOperator() == OO_Delete ||
           FD->getOverloadedOperator() == OO_Array_Delete) &&
          FD->getNumParams() == 1);
}

/// FindAllocationFunctions - Finds the overloads of operator new and delete
/// that are appropriate for the allocation.
bool Sema::FindAllocationFunctions(SourceLocation StartLoc, SourceRange Range,
                                   bool UseGlobal, QualType AllocType,
                                   bool IsArray, Expr **PlaceArgs,
                                   unsigned NumPlaceArgs,
                                   FunctionDecl *&OperatorNew,
                                   FunctionDecl *&OperatorDelete) {
  // --- Choosing an allocation function ---
  // C++ 5.3.4p8 - 14 & 18
  // 1) If UseGlobal is true, only look in the global scope. Else, also look
  //   in the scope of the allocated class.
  // 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(1 + NumPlaceArgs);
  // We don't care about the actual value of this argument.
  // FIXME: Should the Sema create the expression and embed it in the syntax
  // tree? Or should the consumer just recalculate the value?
  IntegerLiteral Size(Context, llvm::APInt::getNullValue(
                      Context.getTargetInfo().getPointerWidth(0)),
                      Context.getSizeType(),
                      SourceLocation());
  AllocArgs[0] = &Size;
  std::copy(PlaceArgs, PlaceArgs + NumPlaceArgs, AllocArgs.begin() + 1);

  // 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);
  DeclarationName DeleteName = Context.DeclarationNames.getCXXOperatorName(
                                        IsArray ? OO_Array_Delete : OO_Delete);

  QualType AllocElemType = Context.getBaseElementType(AllocType);

  if (AllocElemType->isRecordType() && !UseGlobal) {
    CXXRecordDecl *Record
      = cast<CXXRecordDecl>(AllocElemType->getAs<RecordType>()->getDecl());
    if (FindAllocationOverload(StartLoc, Range, NewName, &AllocArgs[0],
                          AllocArgs.size(), Record, /*AllowMissing=*/true,
                          OperatorNew))
      return true;
  }
  if (!OperatorNew) {
    // Didn't find a member overload. Look for a global one.
    DeclareGlobalNewDelete();
    DeclContext *TUDecl = Context.getTranslationUnitDecl();
    if (FindAllocationOverload(StartLoc, Range, NewName, &AllocArgs[0],
                          AllocArgs.size(), TUDecl, /*AllowMissing=*/false,
                          OperatorNew))
      return true;
  }

  // We don't need an operator delete if we're running under
  // -fno-exceptions.
  if (!getLangOpts().Exceptions) {
    OperatorDelete = 0;
    return false;
  }

  // FindAllocationOverload can change the passed in arguments, so we need to
  // copy them back.
  if (NumPlaceArgs > 0)
    std::copy(&AllocArgs[1], AllocArgs.end(), PlaceArgs);

  // 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() && !UseGlobal) {
    CXXRecordDecl *RD
      = cast<CXXRecordDecl>(AllocElemType->getAs<RecordType>()->getDecl());
    LookupQualifiedName(FoundDelete, RD);
  }
  if (FoundDelete.isAmbiguous())
    return true; // FIXME: clean up expressions?

  if (FoundDelete.empty()) {
    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()
  bool isPlacementNew = (NumPlaceArgs > 0 || OperatorNew->param_size() != 1);

  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.
    //
    // FIXME: this comparison should ignore CC and the like.
    QualType ExpectedFunctionType;
    {
      const FunctionProtoType *Proto
        = OperatorNew->getType()->getAs<FunctionProtoType>();

      SmallVector<QualType, 4> ArgTypes;
      ArgTypes.push_back(Context.VoidPtrTy);
      for (unsigned I = 1, N = Proto->getNumArgs(); I < N; ++I)
        ArgTypes.push_back(Proto->getArgType(I));

      FunctionProtoType::ExtProtoInfo EPI;
      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 = 0;
      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, 0, ExpectedFunctionType, Fn, Info))
          continue;
      } else
        Fn = cast<FunctionDecl>((*D)->getUnderlyingDecl());

      if (Context.hasSameType(Fn->getType(), ExpectedFunctionType))
        Matches.push_back(std::make_pair(D.getPair(), Fn));
    }
  } else {
    // C++ [expr.new]p20:
    //   [...] Any non-placement deallocation function matches a
    //   non-placement allocation function. [...]
    for (LookupResult::iterator D = FoundDelete.begin(),
                             DEnd = FoundDelete.end();
         D != DEnd; ++D) {
      if (FunctionDecl *Fn = dyn_cast<FunctionDecl>((*D)->getUnderlyingDecl()))
        if (isNonPlacementDeallocationFunction(Fn))
          Matches.push_back(std::make_pair(D.getPair(), Fn));
    }
  }

  // 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++0x [expr.new]p20:
    //   If the lookup finds the two-parameter form of a usual
    //   deallocation function (3.7.4.2) 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 (NumPlaceArgs && getLangOpts().CPlusPlus11 &&
        isNonPlacementDeallocationFunction(OperatorDelete)) {
      Diag(StartLoc, diag::err_placement_new_non_placement_delete)
        << SourceRange(PlaceArgs[0]->getLocStart(),
                       PlaceArgs[NumPlaceArgs - 1]->getLocEnd());
      Diag(OperatorDelete->getLocation(), diag::note_previous_decl)
        << DeleteName;
    } else {
      CheckAllocationAccess(StartLoc, Range, FoundDelete.getNamingClass(),
                            Matches[0].first);
    }
  }

  return false;
}

/// FindAllocationOverload - Find an fitting overload for the allocation
/// function in the specified scope.
bool Sema::FindAllocationOverload(SourceLocation StartLoc, SourceRange Range,
                                  DeclarationName Name, Expr** Args,
                                  unsigned NumArgs, DeclContext *Ctx,
                                  bool AllowMissing, FunctionDecl *&Operator,
                                  bool Diagnose) {
  LookupResult R(*this, Name, StartLoc, LookupOrdinaryName);
  LookupQualifiedName(R, Ctx);
  if (R.empty()) {
    if (AllowMissing || !Diagnose)
      return false;
    return Diag(StartLoc, diag::err_ovl_no_viable_function_in_call)
      << Name << Range;
  }

  if (R.isAmbiguous())
    return true;

  R.suppressDiagnostics();

  OverloadCandidateSet Candidates(StartLoc);
  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)) {
      AddTemplateOverloadCandidate(FnTemplate, Alloc.getPair(),
                                   /*ExplicitTemplateArgs=*/0,
                                   llvm::makeArrayRef(Args, NumArgs),
                                   Candidates,
                                   /*SuppressUserConversions=*/false);
      continue;
    }

    FunctionDecl *Fn = cast<FunctionDecl>(D);
    AddOverloadCandidate(Fn, Alloc.getPair(),
                         llvm::makeArrayRef(Args, NumArgs), Candidates,
                         /*SuppressUserConversions=*/false);
  }

  // Do the resolution.
  OverloadCandidateSet::iterator Best;
  switch (Candidates.BestViableFunction(*this, StartLoc, Best)) {
  case OR_Success: {
    // Got one!
    FunctionDecl *FnDecl = Best->Function;
    MarkFunctionReferenced(StartLoc, FnDecl);
    // The first argument is size_t, and the first parameter must be size_t,
    // too. This is checked on declaration and can be assumed. (It can't be
    // asserted on, though, since invalid decls are left in there.)
    // Watch out for variadic allocator function.
    unsigned NumArgsInFnDecl = FnDecl->getNumParams();
    for (unsigned i = 0; (i < NumArgs && i < NumArgsInFnDecl); ++i) {
      InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
                                                       FnDecl->getParamDecl(i));

      if (!Diagnose && !CanPerformCopyInitialization(Entity, Owned(Args[i])))
        return true;

      ExprResult Result
        = PerformCopyInitialization(Entity, SourceLocation(), Owned(Args[i]));
      if (Result.isInvalid())
        return true;

      Args[i] = Result.takeAs<Expr>();
    }

    Operator = FnDecl;

    if (CheckAllocationAccess(StartLoc, Range, R.getNamingClass(),
                              Best->FoundDecl, Diagnose) == AR_inaccessible)
      return true;

    return false;
  }

  case OR_No_Viable_Function:
    if (Diagnose) {
      Diag(StartLoc, diag::err_ovl_no_viable_function_in_call)
        << Name << Range;
      Candidates.NoteCandidates(*this, OCD_AllCandidates,
                                llvm::makeArrayRef(Args, NumArgs));
    }
    return true;

  case OR_Ambiguous:
    if (Diagnose) {
      Diag(StartLoc, diag::err_ovl_ambiguous_call)
        << Name << Range;
      Candidates.NoteCandidates(*this, OCD_ViableCandidates,
                                llvm::makeArrayRef(Args, NumArgs));
    }
    return true;

  case OR_Deleted: {
    if (Diagnose) {
      Diag(StartLoc, diag::err_ovl_deleted_call)
        << Best->Function->isDeleted()
        << Name
        << getDeletedOrUnavailableSuffix(Best->Function)
        << Range;
      Candidates.NoteCandidates(*this, OCD_AllCandidates,
                                llvm::makeArrayRef(Args, NumArgs));
    }
    return true;
  }
  }
  llvm_unreachable("Unreachable, bad result from BestViableFunction");
}


/// 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++0x:
///   void* operator new(std::size_t);
///   void* operator new[](std::size_t);
///   void operator delete(void *);
///   void operator delete[](void *);
/// @endcode
/// C++0x operator delete is implicitly noexcept.
/// Note that the placement and nothrow forms of new are *not* implicitly
/// declared. Their use requires including \<new\>.
void Sema::DeclareGlobalNewDelete() {
  if (GlobalNewDeleteDeclared)
    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++0x:
  //     void* operator new(std::size_t);
  //     void* operator new[](std::size_t);
  //     void  operator delete(void*);
  //     void  operator delete[](void*);
  //
  //   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.
  // Note that the C++0x versions of operator delete are deallocation functions,
  // and thus are implicitly noexcept.
  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"),
                                        0);
    getStdBadAlloc()->setImplicit(true);
  }

  GlobalNewDeleteDeclared = true;

  QualType VoidPtr = Context.getPointerType(Context.VoidTy);
  QualType SizeT = Context.getSizeType();
  bool AssumeSaneOperatorNew = getLangOpts().AssumeSaneOperatorNew;

  DeclareGlobalAllocationFunction(
      Context.DeclarationNames.getCXXOperatorName(OO_New),
      VoidPtr, SizeT, AssumeSaneOperatorNew);
  DeclareGlobalAllocationFunction(
      Context.DeclarationNames.getCXXOperatorName(OO_Array_New),
      VoidPtr, SizeT, AssumeSaneOperatorNew);
  DeclareGlobalAllocationFunction(
      Context.DeclarationNames.getCXXOperatorName(OO_Delete),
      Context.VoidTy, VoidPtr);
  DeclareGlobalAllocationFunction(
      Context.DeclarationNames.getCXXOperatorName(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, QualType Argument,
                                           bool AddMallocAttr) {
  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)) {
        QualType InitialParamType =
          Context.getCanonicalType(
            Func->getParamDecl(0)->getType().getUnqualifiedType());
        // FIXME: Do we need to check for default arguments here?
        if (Func->getNumParams() == 1 && InitialParamType == Argument) {
          if(AddMallocAttr && !Func->hasAttr<MallocAttr>())
            Func->addAttr(::new (Context) MallocAttr(SourceLocation(), Context));
          return;
        }
      }
    }
  }

  QualType BadAllocType;
  bool HasBadAllocExceptionSpec
    = (Name.getCXXOverloadedOperator() == OO_New ||
       Name.getCXXOverloadedOperator() == OO_Array_New);
  if (HasBadAllocExceptionSpec && !getLangOpts().CPlusPlus11) {
    assert(StdBadAlloc && "Must have std::bad_alloc declared");
    BadAllocType = Context.getTypeDeclType(getStdBadAlloc());
  }

  FunctionProtoType::ExtProtoInfo EPI;
  if (HasBadAllocExceptionSpec) {
    if (!getLangOpts().CPlusPlus11) {
      EPI.ExceptionSpecType = EST_Dynamic;
      EPI.NumExceptions = 1;
      EPI.Exceptions = &BadAllocType;
    }
  } else {
    EPI.ExceptionSpecType = getLangOpts().CPlusPlus11 ?
                                EST_BasicNoexcept : EST_DynamicNone;
  }

  QualType FnType = Context.getFunctionType(Return, Argument, EPI);
  FunctionDecl *Alloc =
    FunctionDecl::Create(Context, GlobalCtx, SourceLocation(),
                         SourceLocation(), Name,
                         FnType, /*TInfo=*/0, SC_None,
                         SC_None, false, true);
  Alloc->setImplicit();

  if (AddMallocAttr)
    Alloc->addAttr(::new (Context) MallocAttr(SourceLocation(), Context));

  ParmVarDecl *Param = ParmVarDecl::Create(Context, Alloc, SourceLocation(),
                                           SourceLocation(), 0,
                                           Argument, /*TInfo=*/0,
                                           SC_None, SC_None, 0);
  Alloc->setParams(Param);

  // FIXME: Also add this declaration to the IdentifierResolver, but
  // make sure it is at the end of the chain to coincide with the
  // global scope.
  Context.getTranslationUnitDecl()->addDecl(Alloc);
}

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();

  SmallVector<DeclAccessPair,4> Matches;
  for (LookupResult::iterator F = Found.begin(), FEnd = Found.end();
       F != FEnd; ++F) {
    NamedDecl *ND = (*F)->getUnderlyingDecl();

    // Ignore template operator delete members from the check for a usual
    // deallocation function.
    if (isa<FunctionTemplateDecl>(ND))
      continue;

    if (cast<CXXMethodDecl>(ND)->isUsualDeallocationFunction())
      Matches.push_back(F.getPair());
  }

  // There's exactly one suitable operator;  pick it.
  if (Matches.size() == 1) {
    Operator = cast<CXXMethodDecl>(Matches[0]->getUnderlyingDecl());

    if (Operator->isDeleted()) {
      if (Diagnose) {
        Diag(StartLoc, diag::err_deleted_function_use);
        NoteDeletedFunction(Operator);
      }
      return true;
    }

    if (CheckAllocationAccess(StartLoc, SourceRange(), Found.getNamingClass(),
                              Matches[0], Diagnose) == AR_inaccessible)
      return true;

    return false;

  // We found multiple suitable operators;  complain about the ambiguity.
  } else if (!Matches.empty()) {
    if (Diagnose) {
      Diag(StartLoc, diag::err_ambiguous_suitable_delete_member_function_found)
        << Name << RD;

      for (SmallVectorImpl<DeclAccessPair>::iterator
             F = Matches.begin(), FEnd = Matches.end(); F != FEnd; ++F)
        Diag((*F)->getUnderlyingDecl()->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 (LookupResult::iterator F = Found.begin(), FEnd = Found.end();
           F != FEnd; ++F)
        Diag((*F)->getUnderlyingDecl()->getLocation(),
             diag::note_member_declared_here) << Name;
    }
    return true;
  }

  // Look for a global declaration.
  DeclareGlobalNewDelete();
  DeclContext *TUDecl = Context.getTranslationUnitDecl();

  CXXNullPtrLiteralExpr Null(Context.VoidPtrTy, SourceLocation());
  Expr* DeallocArgs[1];
  DeallocArgs[0] = &Null;
  if (FindAllocationOverload(StartLoc, SourceRange(), Name,
                             DeallocArgs, 1, TUDecl, !Diagnose,
                             Operator, Diagnose))
    return true;

  assert(Operator && "Did not find a deallocation function!");
  return false;
}

/// 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
  //   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 = Owned(ExE);
  FunctionDecl *OperatorDelete = 0;
  bool ArrayFormAsWritten = ArrayForm;
  bool UsualArrayDeleteWantsSize = false;

  if (!Ex.get()->isTypeDependent()) {
    // Perform lvalue-to-rvalue cast, if needed.
    Ex = DefaultLvalueConversion(Ex.take());
    if (Ex.isInvalid())
      return ExprError();

    QualType Type = Ex.get()->getType();

    if (const RecordType *Record = Type->getAs<RecordType>()) {
      if (RequireCompleteType(StartLoc, Type,
                              diag::err_delete_incomplete_class_type))
        return ExprError();

      SmallVector<CXXConversionDecl*, 4> ObjectPtrConversions;

      CXXRecordDecl *RD = cast<CXXRecordDecl>(Record->getDecl());
      std::pair<CXXRecordDecl::conversion_iterator,
                CXXRecordDecl::conversion_iterator>
        Conversions = RD->getVisibleConversionFunctions();
      for (CXXRecordDecl::conversion_iterator
             I = Conversions.first, E = Conversions.second; I != E; ++I) {
        NamedDecl *D = I.getDecl();
        if (isa<UsingShadowDecl>(D))
          D = cast<UsingShadowDecl>(D)->getTargetDecl();

        // Skip over templated conversion functions; they aren't considered.
        if (isa<FunctionTemplateDecl>(D))
          continue;

        CXXConversionDecl *Conv = cast<CXXConversionDecl>(D);

        QualType ConvType = Conv->getConversionType().getNonReferenceType();
        if (const PointerType *ConvPtrType = ConvType->getAs<PointerType>())
          if (ConvPtrType->getPointeeType()->isIncompleteOrObjectType())
            ObjectPtrConversions.push_back(Conv);
      }
      if (ObjectPtrConversions.size() == 1) {
        // We have a single conversion to a pointer-to-object type. Perform
        // that conversion.
        // TODO: don't redo the conversion calculation.
        ExprResult Res =
          PerformImplicitConversion(Ex.get(),
                            ObjectPtrConversions.front()->getConversionType(),
                                    AA_Converting);
        if (Res.isUsable()) {
          Ex = Res;
          Type = Ex.get()->getType();
        }
      }
      else if (ObjectPtrConversions.size() > 1) {
        Diag(StartLoc, diag::err_ambiguous_delete_operand)
              << Type << Ex.get()->getSourceRange();
        for (unsigned i= 0; i < ObjectPtrConversions.size(); i++)
          NoteOverloadCandidate(ObjectPtrConversions[i]);
        return ExprError();
      }
    }

    if (!Type->isPointerType())
      return ExprError(Diag(StartLoc, diag::err_delete_operand)
        << Type << Ex.get()->getSourceRange());

    QualType Pointee = Type->getAs<PointerType>()->getPointeeType();
    QualType PointeeElem = Context.getBaseElementType(Pointee);

    if (unsigned AddressSpace = Pointee.getAddressSpace())
      return Diag(Ex.get()->getLocStart(),
                  diag::err_address_space_qualified_delete)
               << Pointee.getUnqualifiedType() << AddressSpace;

    CXXRecordDecl *PointeeRD = 0;
    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()) {
      return ExprError(Diag(StartLoc, diag::err_delete_operand)
        << Type << Ex.get()->getSourceRange());
    } else if (!Pointee->isDependentType()) {
      if (!RequireCompleteType(StartLoc, Pointee,
                               diag::warn_delete_incomplete, Ex.get())) {
        if (const RecordType *RT = PointeeElem->getAs<RecordType>())
          PointeeRD = cast<CXXRecordDecl>(RT->getDecl());
      }
    }

    // C++ [expr.delete]p2:
    //   [Note: a pointer to a const type can be the operand of a
    //   delete-expression; it is not necessary to cast away the constness
    //   (5.2.11) of the pointer expression before it is used as the operand
    //   of the delete-expression. ]

    if (Pointee->isArrayType() && !ArrayForm) {
      Diag(StartLoc, diag::warn_delete_array_type)
          << Type << Ex.get()->getSourceRange()
          << FixItHint::CreateInsertion(PP.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 (isa<CXXMethodDecl>(OperatorDelete))
          UsualArrayDeleteWantsSize = (OperatorDelete->getNumParams() == 2);
      }

      if (!PointeeRD->hasIrrelevantDestructor())
        if (CXXDestructorDecl *Dtor = LookupDestructor(PointeeRD)) {
          MarkFunctionReferenced(StartLoc,
                                    const_cast<CXXDestructorDecl*>(Dtor));
          DiagnoseUseOfDecl(Dtor, StartLoc);
        }

      // 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.
      //
      // Note: a final class cannot be derived from, no issue there
      if (PointeeRD->isPolymorphic() && !PointeeRD->hasAttr<FinalAttr>()) {
        CXXDestructorDecl *dtor = PointeeRD->getDestructor();
        if (dtor && !dtor->isVirtual()) {
          if (PointeeRD->isAbstract()) {
            // If the class is abstract, we warn by default, because we're
            // sure the code has undefined behavior.
            Diag(StartLoc, diag::warn_delete_abstract_non_virtual_dtor)
                << PointeeElem;
          } else if (!ArrayForm) {
            // Otherwise, if this is not an array delete, it's a bit suspect,
            // but not necessarily wrong.
            Diag(StartLoc, diag::warn_delete_non_virtual_dtor) << PointeeElem;
          }
        }
      }

    }

    if (!OperatorDelete) {
      // Look for a global declaration.
      DeclareGlobalNewDelete();
      DeclContext *TUDecl = Context.getTranslationUnitDecl();
      Expr *Arg = Ex.get();
      if (!Context.hasSameType(Arg->getType(), Context.VoidPtrTy))
        Arg = ImplicitCastExpr::Create(Context, Context.VoidPtrTy,
                                       CK_BitCast, Arg, 0, VK_RValue);
      if (FindAllocationOverload(StartLoc, SourceRange(), DeleteName,
                                 &Arg, 1, TUDecl, /*AllowMissing=*/false,
                                 OperatorDelete))
        return ExprError();
    }

    MarkFunctionReferenced(StartLoc, OperatorDelete);

    // Check access and ambiguity of operator delete and destructor.
    if (PointeeRD) {
      if (CXXDestructorDecl *Dtor = LookupDestructor(PointeeRD)) {
          CheckDestructorAccess(Ex.get()->getExprLoc(), Dtor,
                      PDiag(diag::err_access_dtor) << PointeeElem);
      }
    }

  }

  return Owned(new (Context) CXXDeleteExpr(Context.VoidTy, UseGlobal, ArrayForm,
                                           ArrayFormAsWritten,
                                           UsualArrayDeleteWantsSize,
                                           OperatorDelete, Ex.take(), StartLoc));
}

/// \brief 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,
                                        bool ConvertToBoolean) {
  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 =
    Owned(DeclRefExpr::Create(Context, NestedNameSpecifierLoc(),
                              SourceLocation(),
                              ConditionVar,
                              /*enclosing*/ false,
                              ConditionVar->getLocation(),
                              ConditionVar->getType().getNonReferenceType(),
                              VK_LValue));

  MarkDeclRefReferenced(cast<DeclRefExpr>(Condition.get()));

  if (ConvertToBoolean) {
    Condition = CheckBooleanCondition(Condition.take(), StmtLoc);
    if (Condition.isInvalid())
      return ExprError();
  }

  return Condition;
}

/// CheckCXXBooleanCondition - Returns true if a conversion to bool is invalid.
ExprResult Sema::CheckCXXBooleanCondition(Expr *CondExpr) {
  // C++ 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.
  //
  return PerformContextuallyConvertToBool(CondExpr);
}

/// 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 ToPointeeType->isWideCharType();
          }
        }
      }

  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.CompleteConstructorCall(Constructor, From, CastLoc, ConstructorArgs))
      return ExprError();

    S.CheckConstructorAccess(CastLoc, Constructor,
                             InitializedEntity::InitializeTemporary(Ty),
                             Constructor->getAccess());

    ExprResult Result
      = S.BuildCXXConstructExpr(CastLoc, Ty, cast<CXXConstructorDecl>(Method),
                                ConstructorArgs, HadMultipleCandidates,
                                /*ListInit*/ false, /*ZeroInit*/ false,
                                CXXConstructExpr::CK_Complete, SourceRange());
    if (Result.isInvalid())
      return ExprError();

    return S.MaybeBindToTemporary(Result.takeAs<Expr>());
  }

  case CK_UserDefinedConversion: {
    assert(!From->getType()->isPointerType() && "Arg can't have pointer type!");

    // 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 = S.Owned(ImplicitCastExpr::Create(S.Context,
                                              Result.get()->getType(),
                                              CK_UserDefinedConversion,
                                              Result.get(), 0,
                                              Result.get()->getValueKind()));

    S.CheckMemberOperatorAccess(CastLoc, From, /*arg*/ 0, FoundDecl);

    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) {
  switch (ICS.getKind()) {
  case ImplicitConversionSequence::StandardConversion: {
    ExprResult Res = PerformImplicitConversion(From, ToType, ICS.Standard,
                                               Action, CCK);
    if (Res.isInvalid())
      return ExprError();
    From = Res.take();
    break;
  }

  case ImplicitConversionSequence::UserDefinedConversion: {

      FunctionDecl *FD = ICS.UserDefined.ConversionFunction;
      CastKind CastKind;
      QualType BeforeToType;
      assert(FD && "FIXME: aggregate initialization from init list");
      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 elipsis conversion.
      if (!ICS.UserDefined.EllipsisConversion) {
        ExprResult Res =
          PerformImplicitConversion(From, BeforeToType,
                                    ICS.UserDefined.Before, AA_Converting,
                                    CCK);
        if (Res.isInvalid())
          return ExprError();
        From = Res.take();
      }

      ExprResult CastArg
        = BuildCXXCastArgument(*this,
                               From->getLocStart(),
                               ToType.getNonReferenceType(),
                               CastKind, cast<CXXMethodDecl>(FD),
                               ICS.UserDefined.FoundConversionFunction,
                               ICS.UserDefined.HadMultipleCandidates,
                               From);

      if (CastArg.isInvalid())
        return ExprError();

      From = CastArg.take();

      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:
    return ExprError();
  }

  // Everything went well.
  return Owned(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),
                                  From, /*FIXME:ConstructLoc*/SourceLocation(),
                                  ConstructorArgs))
        return ExprError();
      return BuildCXXConstructExpr(/*FIXME:ConstructLoc*/SourceLocation(),
                                   ToType, SCS.CopyConstructor,
                                   ConstructorArgs,
                                   /*HadMultipleCandidates*/ false,
                                   /*ListInit*/ false, /*ZeroInit*/ false,
                                   CXXConstructExpr::CK_Complete,
                                   SourceRange());
    }
    return BuildCXXConstructExpr(/*FIXME:ConstructLoc*/SourceLocation(),
                                 ToType, SCS.CopyConstructor,
                                 From, /*HadMultipleCandidates*/ false,
                                 /*ListInit*/ 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->getLocStart()))
      return ExprError();

    From = FixOverloadedFunctionReference(From, Found, Fn);
    FromType = From->getType();
  }

  // Perform the first implicit conversion.
  switch (SCS.First) {
  case ICK_Identity:
    // Nothing to do.
    break;

  case ICK_Lvalue_To_Rvalue: {
    assert(From->getObjectKind() != OK_ObjCProperty);
    FromType = FromType.getUnqualifiedType();
    ExprResult FromRes = DefaultLvalueConversion(From);
    assert(!FromRes.isInvalid() && "Can't perform deduced conversion?!");
    From = FromRes.take();
    break;
  }

  case ICK_Array_To_Pointer:
    FromType = Context.getArrayDecayedType(FromType);
    From = ImpCastExprToType(From, FromType, CK_ArrayToPointerDecay,
                             VK_RValue, /*BasePath=*/0, CCK).take();
    break;

  case ICK_Function_To_Pointer:
    FromType = Context.getPointerType(FromType);
    From = ImpCastExprToType(From, FromType, CK_FunctionToPointerDecay,
                             VK_RValue, /*BasePath=*/0, CCK).take();
    break;

  default:
    llvm_unreachable("Improper first standard conversion");
  }

  // Perform the second implicit conversion
  switch (SCS.Second) {
  case ICK_Identity:
    // If both sides are functions (or pointers/references to them), there could
    // be incompatible exception declarations.
    if (CheckExceptionSpecCompatibility(From, ToType))
      return ExprError();
    // Nothing else to do.
    break;

  case ICK_NoReturn_Adjustment:
    // 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_RValue, /*BasePath=*/0, CCK).take();
    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_RValue, /*BasePath=*/0, CCK).take();
    } else {
      From = ImpCastExprToType(From, ToType, CK_IntegralCast,
                               VK_RValue, /*BasePath=*/0, CCK).take();
    }
    break;

  case ICK_Floating_Promotion:
  case ICK_Floating_Conversion:
    From = ImpCastExprToType(From, ToType, CK_FloatingCast,
                             VK_RValue, /*BasePath=*/0, CCK).take();
    break;

  case ICK_Complex_Promotion:
  case ICK_Complex_Conversion: {
    QualType FromEl = From->getType()->getAs<ComplexType>()->getElementType();
    QualType ToEl = ToType->getAs<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_RValue, /*BasePath=*/0, CCK).take();
    break;
  }

  case ICK_Floating_Integral:
    if (ToType->isRealFloatingType())
      From = ImpCastExprToType(From, ToType, CK_IntegralToFloating,
                               VK_RValue, /*BasePath=*/0, CCK).take();
    else
      From = ImpCastExprToType(From, ToType, CK_FloatingToIntegral,
                               VK_RValue, /*BasePath=*/0, CCK).take();
    break;

  case ICK_Compatible_Conversion:
      From = ImpCastExprToType(From, ToType, CK_NoOp,
                               VK_RValue, /*BasePath=*/0, CCK).take();
    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->getLocStart(),
             diag::ext_typecheck_convert_incompatible_pointer)
          << ToType << From->getType() << Action
          << From->getSourceRange() << 0;
      else
        Diag(From->getLocStart(),
             diag::ext_typecheck_convert_incompatible_pointer)
          << From->getType() << ToType << Action
          << From->getSourceRange() << 0;

      if (From->getType()->isObjCObjectPointerType() &&
          ToType->isObjCObjectPointerType())
        EmitRelatedResultTypeNote(From);
    }
    else if (getLangOpts().ObjCAutoRefCount &&
             !CheckObjCARCUnavailableWeakConversion(ToType,
                                                    From->getType())) {
      if (Action == AA_Initializing)
        Diag(From->getLocStart(),
             diag::err_arc_weak_unavailable_assign);
      else
        Diag(From->getLocStart(),
             diag::err_arc_convesion_of_weak_unavailable)
          << (Action == AA_Casting) << From->getType() << ToType
          << From->getSourceRange();
    }

    CastKind Kind = CK_Invalid;
    CXXCastPath BasePath;
    if (CheckPointerConversion(From, ToType, 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.take();
    }

    From = ImpCastExprToType(From, ToType, Kind,