text: //===--- SemaType.cpp - Semantic Analysis for Types -----------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file implements type-related semantic analysis.
  //
  //===----------------------------------------------------------------------===//
  
  #include "clang/Sema/SemaInternal.h"
  #include "TypeLocBuilder.h"
  #include "clang/AST/ASTConsumer.h"
  #include "clang/AST/ASTContext.h"
  #include "clang/AST/ASTMutationListener.h"
  #include "clang/AST/CXXInheritance.h"
  #include "clang/AST/DeclObjC.h"
  #include "clang/AST/DeclTemplate.h"
  #include "clang/AST/Expr.h"
  #include "clang/AST/TypeLoc.h"
  #include "clang/AST/TypeLocVisitor.h"
  #include "clang/Basic/PartialDiagnostic.h"
  #include "clang/Basic/TargetInfo.h"
  #include "clang/Parse/ParseDiagnostic.h"
  #include "clang/Sema/DeclSpec.h"
  #include "clang/Sema/DelayedDiagnostic.h"
  #include "clang/Sema/Lookup.h"
  #include "clang/Sema/ScopeInfo.h"
  #include "clang/Sema/Template.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/Support/ErrorHandling.h"
  
  using namespace clang;
  
  enum TypeDiagSelector {
    TDS_Function,
    TDS_Pointer,
    TDS_ObjCObjOrBlock
  };
  
  /// isOmittedBlockReturnType - Return true if this declarator is missing a
  /// return type because this is a omitted return type on a block literal.
  static bool isOmittedBlockReturnType(const Declarator &D) {
    if (D.getContext() != Declarator::BlockLiteralContext ||
        D.getDeclSpec().hasTypeSpecifier())
      return false;
  
    if (D.getNumTypeObjects() == 0)
      return true;   // ^{ ... }
  
    if (D.getNumTypeObjects() == 1 &&
        D.getTypeObject(0).Kind == DeclaratorChunk::Function)
      return true;   // ^(int X, float Y) { ... }
  
    return false;
  }
  
  /// diagnoseBadTypeAttribute - Diagnoses a type attribute which
  /// doesn't apply to the given type.
  static void diagnoseBadTypeAttribute(Sema &S, const AttributeList &attr,
                                       QualType type) {
    TypeDiagSelector WhichType;
    bool useExpansionLoc = true;
    switch (attr.getKind()) {
    case AttributeList::AT_ObjCGC:        WhichType = TDS_Pointer; break;
    case AttributeList::AT_ObjCOwnership: WhichType = TDS_ObjCObjOrBlock; break;
    default:
      // Assume everything else was a function attribute.
      WhichType = TDS_Function;
      useExpansionLoc = false;
      break;
    }
  
    SourceLocation loc = attr.getLoc();
    StringRef name = attr.getName()->getName();
  
    // The GC attributes are usually written with macros;  special-case them.
    IdentifierInfo *II = attr.isArgIdent(0) ? attr.getArgAsIdent(0)->Ident
                                            : nullptr;
    if (useExpansionLoc && loc.isMacroID() && II) {
      if (II->isStr("strong")) {
        if (S.findMacroSpelling(loc, "__strong")) name = "__strong";
      } else if (II->isStr("weak")) {
        if (S.findMacroSpelling(loc, "__weak")) name = "__weak";
      }
    }
  
    S.Diag(loc, diag::warn_type_attribute_wrong_type) << name << WhichType
      << type;
  }
  
  // objc_gc applies to Objective-C pointers or, otherwise, to the
  // smallest available pointer type (i.e. 'void*' in 'void**').
  #define OBJC_POINTER_TYPE_ATTRS_CASELIST \
      case AttributeList::AT_ObjCGC: \
      case AttributeList::AT_ObjCOwnership
  
  // Function type attributes.
  #define FUNCTION_TYPE_ATTRS_CASELIST \
      case AttributeList::AT_NoReturn: \
      case AttributeList::AT_CDecl: \
      case AttributeList::AT_FastCall: \
      case AttributeList::AT_StdCall: \
      case AttributeList::AT_ThisCall: \
      case AttributeList::AT_Pascal: \
      case AttributeList::AT_MSABI: \
      case AttributeList::AT_SysVABI: \
      case AttributeList::AT_Regparm: \
      case AttributeList::AT_Pcs: \
      case AttributeList::AT_PnaclCall: \
      case AttributeList::AT_IntelOclBicc
  
  // Microsoft-specific type qualifiers.
  #define MS_TYPE_ATTRS_CASELIST  \
      case AttributeList::AT_Ptr32: \
      case AttributeList::AT_Ptr64: \
      case AttributeList::AT_SPtr: \
      case AttributeList::AT_UPtr
  
  namespace {
    /// An object which stores processing state for the entire
    /// GetTypeForDeclarator process.
    class TypeProcessingState {
      Sema &sema;
  
      /// The declarator being processed.
      Declarator &declarator;
  
      /// The index of the declarator chunk we're currently processing.
      /// May be the total number of valid chunks, indicating the
      /// DeclSpec.
      unsigned chunkIndex;
  
      /// Whether there are non-trivial modifications to the decl spec.
      bool trivial;
  
      /// Whether we saved the attributes in the decl spec.
      bool hasSavedAttrs;
  
      /// The original set of attributes on the DeclSpec.
      SmallVector<AttributeList*, 2> savedAttrs;
  
      /// A list of attributes to diagnose the uselessness of when the
      /// processing is complete.
      SmallVector<AttributeList*, 2> ignoredTypeAttrs;
  
    public:
      TypeProcessingState(Sema &sema, Declarator &declarator)
        : sema(sema), declarator(declarator),
          chunkIndex(declarator.getNumTypeObjects()),
          trivial(true), hasSavedAttrs(false) {}
  
      Sema &getSema() const {
        return sema;
      }
  
      Declarator &getDeclarator() const {
        return declarator;
      }
  
      bool isProcessingDeclSpec() const {
        return chunkIndex == declarator.getNumTypeObjects();
      }
  
      unsigned getCurrentChunkIndex() const {
        return chunkIndex;
      }
  
      void setCurrentChunkIndex(unsigned idx) {
        assert(idx <= declarator.getNumTypeObjects());
        chunkIndex = idx;
      }
  
      AttributeList *&getCurrentAttrListRef() const {
        if (isProcessingDeclSpec())
          return getMutableDeclSpec().getAttributes().getListRef();
        return declarator.getTypeObject(chunkIndex).getAttrListRef();
      }
  
      /// Save the current set of attributes on the DeclSpec.
      void saveDeclSpecAttrs() {
        // Don't try to save them multiple times.
        if (hasSavedAttrs) return;
  
        DeclSpec &spec = getMutableDeclSpec();
        for (AttributeList *attr = spec.getAttributes().getList(); attr;
               attr = attr->getNext())
          savedAttrs.push_back(attr);
        trivial &= savedAttrs.empty();
        hasSavedAttrs = true;
      }
  
      /// Record that we had nowhere to put the given type attribute.
      /// We will diagnose such attributes later.
      void addIgnoredTypeAttr(AttributeList &attr) {
        ignoredTypeAttrs.push_back(&attr);
      }
  
      /// Diagnose all the ignored type attributes, given that the
      /// declarator worked out to the given type.
      void diagnoseIgnoredTypeAttrs(QualType type) const {
        for (SmallVectorImpl<AttributeList*>::const_iterator
               i = ignoredTypeAttrs.begin(), e = ignoredTypeAttrs.end();
             i != e; ++i)
          diagnoseBadTypeAttribute(getSema(), **i, type);
      }
  
      ~TypeProcessingState() {
        if (trivial) return;
  
        restoreDeclSpecAttrs();
      }
  
    private:
      DeclSpec &getMutableDeclSpec() const {
        return const_cast<DeclSpec&>(declarator.getDeclSpec());
      }
  
      void restoreDeclSpecAttrs() {
        assert(hasSavedAttrs);
  
        if (savedAttrs.empty()) {
          getMutableDeclSpec().getAttributes().set(nullptr);
          return;
        }
  
        getMutableDeclSpec().getAttributes().set(savedAttrs[0]);
        for (unsigned i = 0, e = savedAttrs.size() - 1; i != e; ++i)
          savedAttrs[i]->setNext(savedAttrs[i+1]);
        savedAttrs.back()->setNext(nullptr);
      }
    };
  }
  
  static void spliceAttrIntoList(AttributeList &attr, AttributeList *&head) {
    attr.setNext(head);
    head = &attr;
  }
  
  static void spliceAttrOutOfList(AttributeList &attr, AttributeList *&head) {
    if (head == &attr) {
      head = attr.getNext();
      return;
    }
  
    AttributeList *cur = head;
    while (true) {
      assert(cur && cur->getNext() && "ran out of attrs?");
      if (cur->getNext() == &attr) {
        cur->setNext(attr.getNext());
        return;
      }
      cur = cur->getNext();
    }
  }
  
  static void moveAttrFromListToList(AttributeList &attr,
                                     AttributeList *&fromList,
                                     AttributeList *&toList) {
    spliceAttrOutOfList(attr, fromList);
    spliceAttrIntoList(attr, toList);
  }
  
  /// The location of a type attribute.
  enum TypeAttrLocation {
    /// The attribute is in the decl-specifier-seq.
    TAL_DeclSpec,
    /// The attribute is part of a DeclaratorChunk.
    TAL_DeclChunk,
    /// The attribute is immediately after the declaration's name.
    TAL_DeclName
  };
  
  static void processTypeAttrs(TypeProcessingState &state,
                               QualType &type, TypeAttrLocation TAL,
                               AttributeList *attrs);
  
  static bool handleFunctionTypeAttr(TypeProcessingState &state,
                                     AttributeList &attr,
                                     QualType &type);
  
  static bool handleMSPointerTypeQualifierAttr(TypeProcessingState &state,
                                               AttributeList &attr,
                                               QualType &type);
  
  static bool handleObjCGCTypeAttr(TypeProcessingState &state,
                                   AttributeList &attr, QualType &type);
  
  static bool handleObjCOwnershipTypeAttr(TypeProcessingState &state,
                                         AttributeList &attr, QualType &type);
  
  static bool handleObjCPointerTypeAttr(TypeProcessingState &state,
                                        AttributeList &attr, QualType &type) {
    if (attr.getKind() == AttributeList::AT_ObjCGC)
      return handleObjCGCTypeAttr(state, attr, type);
    assert(attr.getKind() == AttributeList::AT_ObjCOwnership);
    return handleObjCOwnershipTypeAttr(state, attr, type);
  }
  
  /// Given the index of a declarator chunk, check whether that chunk
  /// directly specifies the return type of a function and, if so, find
  /// an appropriate place for it.
  ///
  /// \param i - a notional index which the search will start
  ///   immediately inside
  static DeclaratorChunk *maybeMovePastReturnType(Declarator &declarator,
                                                  unsigned i) {
    assert(i <= declarator.getNumTypeObjects());
  
    DeclaratorChunk *result = nullptr;
  
    // First, look inwards past parens for a function declarator.
    for (; i != 0; --i) {
      DeclaratorChunk &fnChunk = declarator.getTypeObject(i-1);
      switch (fnChunk.Kind) {
      case DeclaratorChunk::Paren:
        continue;
  
      // If we find anything except a function, bail out.
      case DeclaratorChunk::Pointer:
      case DeclaratorChunk::BlockPointer:
      case DeclaratorChunk::Array:
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::MemberPointer:
        return result;
  
      // If we do find a function declarator, scan inwards from that,
      // looking for a block-pointer declarator.
      case DeclaratorChunk::Function:
        for (--i; i != 0; --i) {
          DeclaratorChunk &blockChunk = declarator.getTypeObject(i-1);
          switch (blockChunk.Kind) {
          case DeclaratorChunk::Paren:
          case DeclaratorChunk::Pointer:
          case DeclaratorChunk::Array:
          case DeclaratorChunk::Function:
          case DeclaratorChunk::Reference:
          case DeclaratorChunk::MemberPointer:
            continue;
          case DeclaratorChunk::BlockPointer:
            result = &blockChunk;
            goto continue_outer;
          }
          llvm_unreachable("bad declarator chunk kind");
        }
  
        // If we run out of declarators doing that, we're done.
        return result;
      }
      llvm_unreachable("bad declarator chunk kind");
  
      // Okay, reconsider from our new point.
    continue_outer: ;
    }
  
    // Ran out of chunks, bail out.
    return result;
  }
  
  /// Given that an objc_gc attribute was written somewhere on a
  /// declaration *other* than on the declarator itself (for which, use
  /// distributeObjCPointerTypeAttrFromDeclarator), and given that it
  /// didn't apply in whatever position it was written in, try to move
  /// it to a more appropriate position.
  static void distributeObjCPointerTypeAttr(TypeProcessingState &state,
                                            AttributeList &attr,
                                            QualType type) {
    Declarator &declarator = state.getDeclarator();
  
    // Move it to the outermost normal or block pointer declarator.
    for (unsigned i = state.getCurrentChunkIndex(); i != 0; --i) {
      DeclaratorChunk &chunk = declarator.getTypeObject(i-1);
      switch (chunk.Kind) {
      case DeclaratorChunk::Pointer:
      case DeclaratorChunk::BlockPointer: {
        // But don't move an ARC ownership attribute to the return type
        // of a block.
        DeclaratorChunk *destChunk = nullptr;
        if (state.isProcessingDeclSpec() &&
            attr.getKind() == AttributeList::AT_ObjCOwnership)
          destChunk = maybeMovePastReturnType(declarator, i - 1);
        if (!destChunk) destChunk = &chunk;
  
        moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
                               destChunk->getAttrListRef());
        return;
      }
  
      case DeclaratorChunk::Paren:
      case DeclaratorChunk::Array:
        continue;
  
      // We may be starting at the return type of a block.
      case DeclaratorChunk::Function:
        if (state.isProcessingDeclSpec() &&
            attr.getKind() == AttributeList::AT_ObjCOwnership) {
          if (DeclaratorChunk *dest = maybeMovePastReturnType(declarator, i)) {
            moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
                                   dest->getAttrListRef());
            return;
          }
        }
        goto error;
  
      // Don't walk through these.
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::MemberPointer:
        goto error;
      }
    }
   error:
  
    diagnoseBadTypeAttribute(state.getSema(), attr, type);
  }
  
  /// Distribute an objc_gc type attribute that was written on the
  /// declarator.
  static void
  distributeObjCPointerTypeAttrFromDeclarator(TypeProcessingState &state,
                                              AttributeList &attr,
                                              QualType &declSpecType) {
    Declarator &declarator = state.getDeclarator();
  
    // objc_gc goes on the innermost pointer to something that's not a
    // pointer.
    unsigned innermost = -1U;
    bool considerDeclSpec = true;
    for (unsigned i = 0, e = declarator.getNumTypeObjects(); i != e; ++i) {
      DeclaratorChunk &chunk = declarator.getTypeObject(i);
      switch (chunk.Kind) {
      case DeclaratorChunk::Pointer:
      case DeclaratorChunk::BlockPointer:
        innermost = i;
        continue;
  
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::MemberPointer:
      case DeclaratorChunk::Paren:
      case DeclaratorChunk::Array:
        continue;
  
      case DeclaratorChunk::Function:
        considerDeclSpec = false;
        goto done;
      }
    }
   done:
  
    // That might actually be the decl spec if we weren't blocked by
    // anything in the declarator.
    if (considerDeclSpec) {
      if (handleObjCPointerTypeAttr(state, attr, declSpecType)) {
        // Splice the attribute into the decl spec.  Prevents the
        // attribute from being applied multiple times and gives
        // the source-location-filler something to work with.
        state.saveDeclSpecAttrs();
        moveAttrFromListToList(attr, declarator.getAttrListRef(),
                 declarator.getMutableDeclSpec().getAttributes().getListRef());
        return;
      }
    }
  
    // Otherwise, if we found an appropriate chunk, splice the attribute
    // into it.
    if (innermost != -1U) {
      moveAttrFromListToList(attr, declarator.getAttrListRef(),
                         declarator.getTypeObject(innermost).getAttrListRef());
      return;
    }
  
    // Otherwise, diagnose when we're done building the type.
    spliceAttrOutOfList(attr, declarator.getAttrListRef());
    state.addIgnoredTypeAttr(attr);
  }
  
  /// A function type attribute was written somewhere in a declaration
  /// *other* than on the declarator itself or in the decl spec.  Given
  /// that it didn't apply in whatever position it was written in, try
  /// to move it to a more appropriate position.
  static void distributeFunctionTypeAttr(TypeProcessingState &state,
                                         AttributeList &attr,
                                         QualType type) {
    Declarator &declarator = state.getDeclarator();
  
    // Try to push the attribute from the return type of a function to
    // the function itself.
    for (unsigned i = state.getCurrentChunkIndex(); i != 0; --i) {
      DeclaratorChunk &chunk = declarator.getTypeObject(i-1);
      switch (chunk.Kind) {
      case DeclaratorChunk::Function:
        moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
                               chunk.getAttrListRef());
        return;
  
      case DeclaratorChunk::Paren:
      case DeclaratorChunk::Pointer:
      case DeclaratorChunk::BlockPointer:
      case DeclaratorChunk::Array:
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::MemberPointer:
        continue;
      }
    }
  
    diagnoseBadTypeAttribute(state.getSema(), attr, type);
  }
  
  /// Try to distribute a function type attribute to the innermost
  /// function chunk or type.  Returns true if the attribute was
  /// distributed, false if no location was found.
  static bool
  distributeFunctionTypeAttrToInnermost(TypeProcessingState &state,
                                        AttributeList &attr,
                                        AttributeList *&attrList,
                                        QualType &declSpecType) {
    Declarator &declarator = state.getDeclarator();
  
    // Put it on the innermost function chunk, if there is one.
    for (unsigned i = 0, e = declarator.getNumTypeObjects(); i != e; ++i) {
      DeclaratorChunk &chunk = declarator.getTypeObject(i);
      if (chunk.Kind != DeclaratorChunk::Function) continue;
  
      moveAttrFromListToList(attr, attrList, chunk.getAttrListRef());
      return true;
    }
  
    return handleFunctionTypeAttr(state, attr, declSpecType);
  }
  
  /// A function type attribute was written in the decl spec.  Try to
  /// apply it somewhere.
  static void
  distributeFunctionTypeAttrFromDeclSpec(TypeProcessingState &state,
                                         AttributeList &attr,
                                         QualType &declSpecType) {
    state.saveDeclSpecAttrs();
  
    // C++11 attributes before the decl specifiers actually appertain to
    // the declarators. Move them straight there. We don't support the
    // 'put them wherever you like' semantics we allow for GNU attributes.
    if (attr.isCXX11Attribute()) {
      moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
                             state.getDeclarator().getAttrListRef());
      return;
    }
  
    // Try to distribute to the innermost.
    if (distributeFunctionTypeAttrToInnermost(state, attr,
                                              state.getCurrentAttrListRef(),
                                              declSpecType))
      return;
  
    // If that failed, diagnose the bad attribute when the declarator is
    // fully built.
    state.addIgnoredTypeAttr(attr);
  }
  
  /// A function type attribute was written on the declarator.  Try to
  /// apply it somewhere.
  static void
  distributeFunctionTypeAttrFromDeclarator(TypeProcessingState &state,
                                           AttributeList &attr,
                                           QualType &declSpecType) {
    Declarator &declarator = state.getDeclarator();
  
    // Try to distribute to the innermost.
    if (distributeFunctionTypeAttrToInnermost(state, attr,
                                              declarator.getAttrListRef(),
                                              declSpecType))
      return;
  
    // If that failed, diagnose the bad attribute when the declarator is
    // fully built.
    spliceAttrOutOfList(attr, declarator.getAttrListRef());
    state.addIgnoredTypeAttr(attr);
  }
  
  /// \brief Given that there are attributes written on the declarator
  /// itself, try to distribute any type attributes to the appropriate
  /// declarator chunk.
  ///
  /// These are attributes like the following:
  ///   int f ATTR;
  ///   int (f ATTR)();
  /// but not necessarily this:
  ///   int f() ATTR;
  static void distributeTypeAttrsFromDeclarator(TypeProcessingState &state,
                                                QualType &declSpecType) {
    // Collect all the type attributes from the declarator itself.
    assert(state.getDeclarator().getAttributes() && "declarator has no attrs!");
    AttributeList *attr = state.getDeclarator().getAttributes();
    AttributeList *next;
    do {
      next = attr->getNext();
  
      // Do not distribute C++11 attributes. They have strict rules for what
      // they appertain to.
      if (attr->isCXX11Attribute())
        continue;
  
      switch (attr->getKind()) {
      OBJC_POINTER_TYPE_ATTRS_CASELIST:
        distributeObjCPointerTypeAttrFromDeclarator(state, *attr, declSpecType);
        break;
  
      case AttributeList::AT_NSReturnsRetained:
        if (!state.getSema().getLangOpts().ObjCAutoRefCount)
          break;
        // fallthrough
  
      FUNCTION_TYPE_ATTRS_CASELIST:
        distributeFunctionTypeAttrFromDeclarator(state, *attr, declSpecType);
        break;
  
      MS_TYPE_ATTRS_CASELIST:
        // Microsoft type attributes cannot go after the declarator-id.
        continue;
  
      default:
        break;
      }
    } while ((attr = next));
  }
  
  /// Add a synthetic '()' to a block-literal declarator if it is
  /// required, given the return type.
  static void maybeSynthesizeBlockSignature(TypeProcessingState &state,
                                            QualType declSpecType) {
    Declarator &declarator = state.getDeclarator();
  
    // First, check whether the declarator would produce a function,
    // i.e. whether the innermost semantic chunk is a function.
    if (declarator.isFunctionDeclarator()) {
      // If so, make that declarator a prototyped declarator.
      declarator.getFunctionTypeInfo().hasPrototype = true;
      return;
    }
  
    // If there are any type objects, the type as written won't name a
    // function, regardless of the decl spec type.  This is because a
    // block signature declarator is always an abstract-declarator, and
    // abstract-declarators can't just be parentheses chunks.  Therefore
    // we need to build a function chunk unless there are no type
    // objects and the decl spec type is a function.
    if (!declarator.getNumTypeObjects() && declSpecType->isFunctionType())
      return;
  
    // Note that there *are* cases with invalid declarators where
    // declarators consist solely of parentheses.  In general, these
    // occur only in failed efforts to make function declarators, so
    // faking up the function chunk is still the right thing to do.
  
    // Otherwise, we need to fake up a function declarator.
    SourceLocation loc = declarator.getLocStart();
  
    // ...and *prepend* it to the declarator.
    SourceLocation NoLoc;
    declarator.AddInnermostTypeInfo(DeclaratorChunk::getFunction(
                               /*HasProto=*/true,
                               /*IsAmbiguous=*/false,
                               /*LParenLoc=*/NoLoc,
                               /*ArgInfo=*/nullptr,
                               /*NumArgs=*/0,
                               /*EllipsisLoc=*/NoLoc,
                               /*RParenLoc=*/NoLoc,
                               /*TypeQuals=*/0,
                               /*RefQualifierIsLvalueRef=*/true,
                               /*RefQualifierLoc=*/NoLoc,
                               /*ConstQualifierLoc=*/NoLoc,
                               /*VolatileQualifierLoc=*/NoLoc,
                               /*MutableLoc=*/NoLoc,
                               EST_None,
                               /*ESpecLoc=*/NoLoc,
                               /*Exceptions=*/nullptr,
                               /*ExceptionRanges=*/nullptr,
                               /*NumExceptions=*/0,
                               /*NoexceptExpr=*/nullptr,
                               loc, loc, declarator));
  
    // For consistency, make sure the state still has us as processing
    // the decl spec.
    assert(state.getCurrentChunkIndex() == declarator.getNumTypeObjects() - 1);
    state.setCurrentChunkIndex(declarator.getNumTypeObjects());
  }
  
  /// \brief Convert the specified declspec to the appropriate type
  /// object.
  /// \param state Specifies the declarator containing the declaration specifier
  /// to be converted, along with other associated processing state.
  /// \returns The type described by the declaration specifiers.  This function
  /// never returns null.
  static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
    // FIXME: Should move the logic from DeclSpec::Finish to here for validity
    // checking.
  
    Sema &S = state.getSema();
    Declarator &declarator = state.getDeclarator();
    const DeclSpec &DS = declarator.getDeclSpec();
    SourceLocation DeclLoc = declarator.getIdentifierLoc();
    if (DeclLoc.isInvalid())
      DeclLoc = DS.getLocStart();
  
    ASTContext &Context = S.Context;
  
    QualType Result;
    switch (DS.getTypeSpecType()) {
    case DeclSpec::TST_void:
      Result = Context.VoidTy;
      break;
    case DeclSpec::TST_char:
      if (DS.getTypeSpecSign() == DeclSpec::TSS_unspecified)
        Result = Context.CharTy;
      else if (DS.getTypeSpecSign() == DeclSpec::TSS_signed)
        Result = Context.SignedCharTy;
      else {
        assert(DS.getTypeSpecSign() == DeclSpec::TSS_unsigned &&
               "Unknown TSS value");
        Result = Context.UnsignedCharTy;
      }
      break;
    case DeclSpec::TST_wchar:
      if (DS.getTypeSpecSign() == DeclSpec::TSS_unspecified)
        Result = Context.WCharTy;
      else if (DS.getTypeSpecSign() == DeclSpec::TSS_signed) {
        S.Diag(DS.getTypeSpecSignLoc(), diag::ext_invalid_sign_spec)
          << DS.getSpecifierName(DS.getTypeSpecType(),
                                 Context.getPrintingPolicy());
        Result = Context.getSignedWCharType();
      } else {
        assert(DS.getTypeSpecSign() == DeclSpec::TSS_unsigned &&
          "Unknown TSS value");
        S.Diag(DS.getTypeSpecSignLoc(), diag::ext_invalid_sign_spec)
          << DS.getSpecifierName(DS.getTypeSpecType(),
                                 Context.getPrintingPolicy());
        Result = Context.getUnsignedWCharType();
      }
      break;
    case DeclSpec::TST_char16:
        assert(DS.getTypeSpecSign() == DeclSpec::TSS_unspecified &&
          "Unknown TSS value");
        Result = Context.Char16Ty;
      break;
    case DeclSpec::TST_char32:
        assert(DS.getTypeSpecSign() == DeclSpec::TSS_unspecified &&
          "Unknown TSS value");
        Result = Context.Char32Ty;
      break;
    case DeclSpec::TST_unspecified:
      // "<proto1,proto2>" is an objc qualified ID with a missing id.
      if (DeclSpec::ProtocolQualifierListTy PQ = DS.getProtocolQualifiers()) {
        Result = Context.getObjCObjectType(Context.ObjCBuiltinIdTy,
                                           (ObjCProtocolDecl*const*)PQ,
                                           DS.getNumProtocolQualifiers());
        Result = Context.getObjCObjectPointerType(Result);
        break;
      }
  
      // If this is a missing declspec in a block literal return context, then it
      // is inferred from the return statements inside the block.
      // The declspec is always missing in a lambda expr context; it is either
      // specified with a trailing return type or inferred.
      if (S.getLangOpts().CPlusPlus1y &&
          declarator.getContext() == Declarator::LambdaExprContext) {
        // In C++1y, a lambda's implicit return type is 'auto'.
        Result = Context.getAutoDeductType();
        break;
      } else if (declarator.getContext() == Declarator::LambdaExprContext ||
                 isOmittedBlockReturnType(declarator)) {
        Result = Context.DependentTy;
        break;
      }
  
      // Unspecified typespec defaults to int in C90.  However, the C90 grammar
      // [C90 6.5] only allows a decl-spec if there was *some* type-specifier,
      // type-qualifier, or storage-class-specifier.  If not, emit an extwarn.
      // Note that the one exception to this is function definitions, which are
      // allowed to be completely missing a declspec.  This is handled in the
      // parser already though by it pretending to have seen an 'int' in this
      // case.
      if (S.getLangOpts().ImplicitInt) {
        // In C89 mode, we only warn if there is a completely missing declspec
        // when one is not allowed.
        if (DS.isEmpty()) {
          S.Diag(DeclLoc, diag::ext_missing_declspec)
            << DS.getSourceRange()
          << FixItHint::CreateInsertion(DS.getLocStart(), "int");
        }
      } else if (!DS.hasTypeSpecifier()) {
        // C99 and C++ require a type specifier.  For example, C99 6.7.2p2 says:
        // "At least one type specifier shall be given in the declaration
        // specifiers in each declaration, and in the specifier-qualifier list in
        // each struct declaration and type name."
        if (S.getLangOpts().CPlusPlus) {
          S.Diag(DeclLoc, diag::err_missing_type_specifier)
            << DS.getSourceRange();
  
          // When this occurs in C++ code, often something is very broken with the
          // value being declared, poison it as invalid so we don't get chains of
          // errors.
          declarator.setInvalidType(true);
        } else {
          S.Diag(DeclLoc, diag::ext_missing_type_specifier)
            << DS.getSourceRange();
        }
      }
  
      // FALL THROUGH.
    case DeclSpec::TST_int: {
      if (DS.getTypeSpecSign() != DeclSpec::TSS_unsigned) {
        switch (DS.getTypeSpecWidth()) {
        case DeclSpec::TSW_unspecified: Result = Context.IntTy; break;
        case DeclSpec::TSW_short:       Result = Context.ShortTy; break;
        case DeclSpec::TSW_long:        Result = Context.LongTy; break;
        case DeclSpec::TSW_longlong:
          Result = Context.LongLongTy;
  
          // 'long long' is a C99 or C++11 feature.
          if (!S.getLangOpts().C99) {
            if (S.getLangOpts().CPlusPlus)
              S.Diag(DS.getTypeSpecWidthLoc(),
                     S.getLangOpts().CPlusPlus11 ?
                     diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
            else
              S.Diag(DS.getTypeSpecWidthLoc(), diag::ext_c99_longlong);
          }
          break;
        }
      } else {
        switch (DS.getTypeSpecWidth()) {
        case DeclSpec::TSW_unspecified: Result = Context.UnsignedIntTy; break;
        case DeclSpec::TSW_short:       Result = Context.UnsignedShortTy; break;
        case DeclSpec::TSW_long:        Result = Context.UnsignedLongTy; break;
        case DeclSpec::TSW_longlong:
          Result = Context.UnsignedLongLongTy;
  
          // 'long long' is a C99 or C++11 feature.
          if (!S.getLangOpts().C99) {
            if (S.getLangOpts().CPlusPlus)
              S.Diag(DS.getTypeSpecWidthLoc(),
                     S.getLangOpts().CPlusPlus11 ?
                     diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
            else
              S.Diag(DS.getTypeSpecWidthLoc(), diag::ext_c99_longlong);
          }
          break;
        }
      }
      break;
    }
    case DeclSpec::TST_int128:
      if (!S.Context.getTargetInfo().hasInt128Type())
        S.Diag(DS.getTypeSpecTypeLoc(), diag::err_int128_unsupported);
      if (DS.getTypeSpecSign() == DeclSpec::TSS_unsigned)
        Result = Context.UnsignedInt128Ty;
      else
        Result = Context.Int128Ty;
      break;
    case DeclSpec::TST_half: Result = Context.HalfTy; break;
    case DeclSpec::TST_float: Result = Context.FloatTy; break;
    case DeclSpec::TST_double:
      if (DS.getTypeSpecWidth() == DeclSpec::TSW_long)
        Result = Context.LongDoubleTy;
      else
        Result = Context.DoubleTy;
  
      if (S.getLangOpts().OpenCL && !S.getOpenCLOptions().cl_khr_fp64) {
        S.Diag(DS.getTypeSpecTypeLoc(), diag::err_double_requires_fp64);
        declarator.setInvalidType(true);
      }
      break;
    case DeclSpec::TST_bool: Result = Context.BoolTy; break; // _Bool or bool
    case DeclSpec::TST_decimal32:    // _Decimal32
    case DeclSpec::TST_decimal64:    // _Decimal64
    case DeclSpec::TST_decimal128:   // _Decimal128
      S.Diag(DS.getTypeSpecTypeLoc(), diag::err_decimal_unsupported);
      Result = Context.IntTy;
      declarator.setInvalidType(true);
      break;
    case DeclSpec::TST_class:
    case DeclSpec::TST_enum:
    case DeclSpec::TST_union:
    case DeclSpec::TST_struct:
    case DeclSpec::TST_interface: {
      TypeDecl *D = dyn_cast_or_null<TypeDecl>(DS.getRepAsDecl());
      if (!D) {
        // This can happen in C++ with ambiguous lookups.
        Result = Context.IntTy;
        declarator.setInvalidType(true);
        break;
      }
  
      // If the type is deprecated or unavailable, diagnose it.
      S.DiagnoseUseOfDecl(D, DS.getTypeSpecTypeNameLoc());
  
      assert(DS.getTypeSpecWidth() == 0 && DS.getTypeSpecComplex() == 0 &&
             DS.getTypeSpecSign() == 0 && "No qualifiers on tag names!");
  
      // TypeQuals handled by caller.
      Result = Context.getTypeDeclType(D);
  
      // In both C and C++, make an ElaboratedType.
      ElaboratedTypeKeyword Keyword
        = ElaboratedType::getKeywordForTypeSpec(DS.getTypeSpecType());
      Result = S.getElaboratedType(Keyword, DS.getTypeSpecScope(), Result);
      break;
    }
    case DeclSpec::TST_typename: {
      assert(DS.getTypeSpecWidth() == 0 && DS.getTypeSpecComplex() == 0 &&
             DS.getTypeSpecSign() == 0 &&
             "Can't handle qualifiers on typedef names yet!");
      Result = S.GetTypeFromParser(DS.getRepAsType());
      if (Result.isNull())
        declarator.setInvalidType(true);
      else if (DeclSpec::ProtocolQualifierListTy PQ
                 = DS.getProtocolQualifiers()) {
        if (const ObjCObjectType *ObjT = Result->getAs<ObjCObjectType>()) {
          // Silently drop any existing protocol qualifiers.
          // TODO: determine whether that's the right thing to do.
          if (ObjT->getNumProtocols())
            Result = ObjT->getBaseType();
  
          if (DS.getNumProtocolQualifiers())
            Result = Context.getObjCObjectType(Result,
                                               (ObjCProtocolDecl*const*) PQ,
                                               DS.getNumProtocolQualifiers());
        } else if (Result->isObjCIdType()) {
          // id<protocol-list>
          Result = Context.getObjCObjectType(Context.ObjCBuiltinIdTy,
                                             (ObjCProtocolDecl*const*) PQ,
                                             DS.getNumProtocolQualifiers());
          Result = Context.getObjCObjectPointerType(Result);
        } else if (Result->isObjCClassType()) {
          // Class<protocol-list>
          Result = Context.getObjCObjectType(Context.ObjCBuiltinClassTy,
                                             (ObjCProtocolDecl*const*) PQ,
                                             DS.getNumProtocolQualifiers());
          Result = Context.getObjCObjectPointerType(Result);
        } else {
          S.Diag(DeclLoc, diag::err_invalid_protocol_qualifiers)
            << DS.getSourceRange();
          declarator.setInvalidType(true);
        }
      }
  
      // TypeQuals handled by caller.
      break;
    }
    case DeclSpec::TST_typeofType:
      // FIXME: Preserve type source info.
      Result = S.GetTypeFromParser(DS.getRepAsType());
      assert(!Result.isNull() && "Didn't get a type for typeof?");
      if (!Result->isDependentType())
        if (const TagType *TT = Result->getAs<TagType>())
          S.DiagnoseUseOfDecl(TT->getDecl(), DS.getTypeSpecTypeLoc());
      // TypeQuals handled by caller.
      Result = Context.getTypeOfType(Result);
      break;
    case DeclSpec::TST_typeofExpr: {
      Expr *E = DS.getRepAsExpr();
      assert(E && "Didn't get an expression for typeof?");
      // TypeQuals handled by caller.
      Result = S.BuildTypeofExprType(E, DS.getTypeSpecTypeLoc());
      if (Result.isNull()) {
        Result = Context.IntTy;
        declarator.setInvalidType(true);
      }
      break;
    }
    case DeclSpec::TST_decltype: {
      Expr *E = DS.getRepAsExpr();
      assert(E && "Didn't get an expression for decltype?");
      // TypeQuals handled by caller.
      Result = S.BuildDecltypeType(E, DS.getTypeSpecTypeLoc());
      if (Result.isNull()) {
        Result = Context.IntTy;
        declarator.setInvalidType(true);
      }
      break;
    }
    case DeclSpec::TST_underlyingType:
      Result = S.GetTypeFromParser(DS.getRepAsType());
      assert(!Result.isNull() && "Didn't get a type for __underlying_type?");
      Result = S.BuildUnaryTransformType(Result,
                                         UnaryTransformType::EnumUnderlyingType,
                                         DS.getTypeSpecTypeLoc());
      if (Result.isNull()) {
        Result = Context.IntTy;
        declarator.setInvalidType(true);
      }
      break;
  
    case DeclSpec::TST_auto:
      // TypeQuals handled by caller.
      // If auto is mentioned in a lambda parameter context, convert it to a 
      // template parameter type immediately, with the appropriate depth and 
      // index, and update sema's state (LambdaScopeInfo) for the current lambda 
      // being analyzed (which tracks the invented type template parameter).
      if (declarator.getContext() == Declarator::LambdaExprParameterContext) {
        sema::LambdaScopeInfo *LSI = S.getCurLambda();
        assert(LSI && "No LambdaScopeInfo on the stack!");
        const unsigned TemplateParameterDepth = LSI->AutoTemplateParameterDepth;
        const unsigned AutoParameterPosition = LSI->AutoTemplateParams.size();
        const bool IsParameterPack = declarator.hasEllipsis();
        
        // Create a name for the invented template parameter type.
        std::string InventedTemplateParamName = "$auto-";
        llvm::raw_string_ostream ss(InventedTemplateParamName);
        ss << TemplateParameterDepth; 
        ss << "-" << AutoParameterPosition;
        ss.flush();
  
        IdentifierInfo& TemplateParamII = Context.Idents.get(
                                          InventedTemplateParamName.c_str());
        // Turns out we must create the TemplateTypeParmDecl here to 
        // retrieve the corresponding template parameter type. 
        TemplateTypeParmDecl *CorrespondingTemplateParam =
          TemplateTypeParmDecl::Create(Context, 
          // Temporarily add to the TranslationUnit DeclContext.  When the 
          // associated TemplateParameterList is attached to a template
          // declaration (such as FunctionTemplateDecl), the DeclContext 
          // for each template parameter gets updated appropriately via
          // a call to AdoptTemplateParameterList. 
          Context.getTranslationUnitDecl(), 
          /*KeyLoc*/ SourceLocation(), 
          /*NameLoc*/ declarator.getLocStart(),  
          TemplateParameterDepth, 
          AutoParameterPosition,  // our template param index 
          /* Identifier*/ &TemplateParamII, false, IsParameterPack);
        LSI->AutoTemplateParams.push_back(CorrespondingTemplateParam);
        // Replace the 'auto' in the function parameter with this invented 
        // template type parameter.
        Result = QualType(CorrespondingTemplateParam->getTypeForDecl(), 0);  
      } else {
        Result = Context.getAutoType(QualType(), /*decltype(auto)*/false, false);
      }
      break;
  
    case DeclSpec::TST_decltype_auto:
      Result = Context.getAutoType(QualType(), 
                                   /*decltype(auto)*/true, 
                                   /*IsDependent*/   false);
      break;
  
    case DeclSpec::TST_unknown_anytype:
      Result = Context.UnknownAnyTy;
      break;
  
    case DeclSpec::TST_atomic:
      Result = S.GetTypeFromParser(DS.getRepAsType());
      assert(!Result.isNull() && "Didn't get a type for _Atomic?");
      Result = S.BuildAtomicType(Result, DS.getTypeSpecTypeLoc());
      if (Result.isNull()) {
        Result = Context.IntTy;
        declarator.setInvalidType(true);
      }
      break;
  
    case DeclSpec::TST_error:
      Result = Context.IntTy;
      declarator.setInvalidType(true);
      break;
    }
  
    // Handle complex types.
    if (DS.getTypeSpecComplex() == DeclSpec::TSC_complex) {
      if (S.getLangOpts().Freestanding)
        S.Diag(DS.getTypeSpecComplexLoc(), diag::ext_freestanding_complex);
      Result = Context.getComplexType(Result);
    } else if (DS.isTypeAltiVecVector()) {
      unsigned typeSize = static_cast<unsigned>(Context.getTypeSize(Result));
      assert(typeSize > 0 && "type size for vector must be greater than 0 bits");
      VectorType::VectorKind VecKind = VectorType::AltiVecVector;
      if (DS.isTypeAltiVecPixel())
        VecKind = VectorType::AltiVecPixel;
      else if (DS.isTypeAltiVecBool())
        VecKind = VectorType::AltiVecBool;
      Result = Context.getVectorType(Result, 128/typeSize, VecKind);
    }
  
    // FIXME: Imaginary.
    if (DS.getTypeSpecComplex() == DeclSpec::TSC_imaginary)
      S.Diag(DS.getTypeSpecComplexLoc(), diag::err_imaginary_not_supported);
  
    // Before we process any type attributes, synthesize a block literal
    // function declarator if necessary.
    if (declarator.getContext() == Declarator::BlockLiteralContext)
      maybeSynthesizeBlockSignature(state, Result);
  
    // Apply any type attributes from the decl spec.  This may cause the
    // list of type attributes to be temporarily saved while the type
    // attributes are pushed around.
    if (AttributeList *attrs = DS.getAttributes().getList())
      processTypeAttrs(state, Result, TAL_DeclSpec, attrs);
  
    // Apply const/volatile/restrict qualifiers to T.
    if (unsigned TypeQuals = DS.getTypeQualifiers()) {
  
      // Warn about CV qualifiers on functions: C99 6.7.3p8: "If the specification
      // of a function type includes any type qualifiers, the behavior is
      // undefined."
      if (Result->isFunctionType() && TypeQuals) {
        if (TypeQuals & DeclSpec::TQ_const)
          S.Diag(DS.getConstSpecLoc(), diag::warn_typecheck_function_qualifiers)
            << Result << DS.getSourceRange();
        else if (TypeQuals & DeclSpec::TQ_volatile)
          S.Diag(DS.getVolatileSpecLoc(), diag::warn_typecheck_function_qualifiers)
            << Result << DS.getSourceRange();
        else {
          assert((TypeQuals & (DeclSpec::TQ_restrict | DeclSpec::TQ_atomic)) &&
                 "Has CVRA quals but not C, V, R, or A?");
          // No diagnostic; we'll diagnose 'restrict' or '_Atomic' applied to a
          // function type later, in BuildQualifiedType.
        }
      }
  
      // C++11 [dcl.ref]p1:
      //   Cv-qualified references are ill-formed except when the
      //   cv-qualifiers are introduced through the use of a typedef-name
      //   or decltype-specifier, in which case the cv-qualifiers are ignored.
      //
      // There don't appear to be any other contexts in which a cv-qualified
      // reference type could be formed, so the 'ill-formed' clause here appears
      // to never happen.
      if (DS.getTypeSpecType() == DeclSpec::TST_typename &&
          TypeQuals && Result->isReferenceType()) {
        // If this occurs outside a template instantiation, warn the user about
        // it; they probably didn't mean to specify a redundant qualifier.
        typedef std::pair<DeclSpec::TQ, SourceLocation> QualLoc;
        QualLoc Quals[] = {
          QualLoc(DeclSpec::TQ_const, DS.getConstSpecLoc()),
          QualLoc(DeclSpec::TQ_volatile, DS.getVolatileSpecLoc()),
          QualLoc(DeclSpec::TQ_atomic, DS.getAtomicSpecLoc())
        };
        for (unsigned I = 0, N = llvm::array_lengthof(Quals); I != N; ++I) {
          if (S.ActiveTemplateInstantiations.empty()) {
            if (TypeQuals & Quals[I].first)
              S.Diag(Quals[I].second, diag::warn_typecheck_reference_qualifiers)
                << DeclSpec::getSpecifierName(Quals[I].first) << Result
                << FixItHint::CreateRemoval(Quals[I].second);
          }
          TypeQuals &= ~Quals[I].first;
        }
      }
  
      // C90 6.5.3 constraints: "The same type qualifier shall not appear more
      // than once in the same specifier-list or qualifier-list, either directly
      // or via one or more typedefs."
      if (!S.getLangOpts().C99 && !S.getLangOpts().CPlusPlus
          && TypeQuals & Result.getCVRQualifiers()) {
        if (TypeQuals & DeclSpec::TQ_const && Result.isConstQualified()) {
          S.Diag(DS.getConstSpecLoc(), diag::ext_duplicate_declspec)
            << "const";
        }
  
        if (TypeQuals & DeclSpec::TQ_volatile && Result.isVolatileQualified()) {
          S.Diag(DS.getVolatileSpecLoc(), diag::ext_duplicate_declspec)
            << "volatile";
        }
  
        // C90 doesn't have restrict nor _Atomic, so it doesn't force us to
        // produce a warning in this case.
      }
  
      QualType Qualified = S.BuildQualifiedType(Result, DeclLoc, TypeQuals, &DS);
  
      // If adding qualifiers fails, just use the unqualified type.
      if (Qualified.isNull())
        declarator.setInvalidType(true);
      else
        Result = Qualified;
    }
  
    return Result;
  }
  
  static std::string getPrintableNameForEntity(DeclarationName Entity) {
    if (Entity)
      return Entity.getAsString();
  
    return "type name";
  }
  
  QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
                                    Qualifiers Qs, const DeclSpec *DS) {
    // Enforce C99 6.7.3p2: "Types other than pointer types derived from
    // object or incomplete types shall not be restrict-qualified."
    if (Qs.hasRestrict()) {
      unsigned DiagID = 0;
      QualType ProblemTy;
  
      if (T->isAnyPointerType() || T->isReferenceType() ||
          T->isMemberPointerType()) {
        QualType EltTy;
        if (T->isObjCObjectPointerType())
          EltTy = T;
        else if (const MemberPointerType *PTy = T->getAs<MemberPointerType>())
          EltTy = PTy->getPointeeType();
        else
          EltTy = T->getPointeeType();
  
        // If we have a pointer or reference, the pointee must have an object
        // incomplete type.
        if (!EltTy->isIncompleteOrObjectType()) {
          DiagID = diag::err_typecheck_invalid_restrict_invalid_pointee;
          ProblemTy = EltTy;
        }
      } else if (!T->isDependentType()) {
        DiagID = diag::err_typecheck_invalid_restrict_not_pointer;
        ProblemTy = T;
      }
  
      if (DiagID) {
        Diag(DS ? DS->getRestrictSpecLoc() : Loc, DiagID) << ProblemTy;
        Qs.removeRestrict();
      }
    }
  
    return Context.getQualifiedType(T, Qs);
  }
  
  QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
                                    unsigned CVRA, const DeclSpec *DS) {
    // Convert from DeclSpec::TQ to Qualifiers::TQ by just dropping TQ_atomic.
    unsigned CVR = CVRA & ~DeclSpec::TQ_atomic;
  
    // C11 6.7.3/5:
    //   If the same qualifier appears more than once in the same
    //   specifier-qualifier-list, either directly or via one or more typedefs,
    //   the behavior is the same as if it appeared only once.
    //
    // It's not specified what happens when the _Atomic qualifier is applied to
    // a type specified with the _Atomic specifier, but we assume that this
    // should be treated as if the _Atomic qualifier appeared multiple times.
    if (CVRA & DeclSpec::TQ_atomic && !T->isAtomicType()) {
      // C11 6.7.3/5:
      //   If other qualifiers appear along with the _Atomic qualifier in a
      //   specifier-qualifier-list, the resulting type is the so-qualified
      //   atomic type.
      //
      // Don't need to worry about array types here, since _Atomic can't be
      // applied to such types.
      SplitQualType Split = T.getSplitUnqualifiedType();
      T = BuildAtomicType(QualType(Split.Ty, 0),
                          DS ? DS->getAtomicSpecLoc() : Loc);
      if (T.isNull())
        return T;
      Split.Quals.addCVRQualifiers(CVR);
      return BuildQualifiedType(T, Loc, Split.Quals);
    }
  
    return BuildQualifiedType(T, Loc, Qualifiers::fromCVRMask(CVR), DS);
  }
  
  /// \brief Build a paren type including \p T.
  QualType Sema::BuildParenType(QualType T) {
    return Context.getParenType(T);
  }
  
  /// Given that we're building a pointer or reference to the given
  static QualType inferARCLifetimeForPointee(Sema &S, QualType type,
                                             SourceLocation loc,
                                             bool isReference) {
    // Bail out if retention is unrequired or already specified.
    if (!type->isObjCLifetimeType() ||
        type.getObjCLifetime() != Qualifiers::OCL_None)
      return type;
  
    Qualifiers::ObjCLifetime implicitLifetime = Qualifiers::OCL_None;
  
    // If the object type is const-qualified, we can safely use
    // __unsafe_unretained.  This is safe (because there are no read
    // barriers), and it'll be safe to coerce anything but __weak* to
    // the resulting type.
    if (type.isConstQualified()) {
      implicitLifetime = Qualifiers::OCL_ExplicitNone;
  
    // Otherwise, check whether the static type does not require
    // retaining.  This currently only triggers for Class (possibly
    // protocol-qualifed, and arrays thereof).
    } else if (type->isObjCARCImplicitlyUnretainedType()) {
      implicitLifetime = Qualifiers::OCL_ExplicitNone;
  
    // If we are in an unevaluated context, like sizeof, skip adding a
    // qualification.
    } else if (S.isUnevaluatedContext()) {
      return type;
  
    // If that failed, give an error and recover using __strong.  __strong
    // is the option most likely to prevent spurious second-order diagnostics,
    // like when binding a reference to a field.
    } else {
      // These types can show up in private ivars in system headers, so
      // we need this to not be an error in those cases.  Instead we
      // want to delay.
      if (S.DelayedDiagnostics.shouldDelayDiagnostics()) {
        S.DelayedDiagnostics.add(
            sema::DelayedDiagnostic::makeForbiddenType(loc,
                diag::err_arc_indirect_no_ownership, type, isReference));
      } else {
        S.Diag(loc, diag::err_arc_indirect_no_ownership) << type << isReference;
      }
      implicitLifetime = Qualifiers::OCL_Strong;
    }
    assert(implicitLifetime && "didn't infer any lifetime!");
  
    Qualifiers qs;
    qs.addObjCLifetime(implicitLifetime);
    return S.Context.getQualifiedType(type, qs);
  }
  
  static std::string getFunctionQualifiersAsString(const FunctionProtoType *FnTy){
    std::string Quals =
      Qualifiers::fromCVRMask(FnTy->getTypeQuals()).getAsString();
  
    switch (FnTy->getRefQualifier()) {
    case RQ_None:
      break;
  
    case RQ_LValue:
      if (!Quals.empty())
        Quals += ' ';
      Quals += '&';
      break;
  
    case RQ_RValue:
      if (!Quals.empty())
        Quals += ' ';
      Quals += "&&";
      break;
    }
  
    return Quals;
  }
  
  namespace {
  /// Kinds of declarator that cannot contain a qualified function type.
  ///
  /// C++98 [dcl.fct]p4 / C++11 [dcl.fct]p6:
  ///     a function type with a cv-qualifier or a ref-qualifier can only appear
  ///     at the topmost level of a type.
  ///
  /// Parens and member pointers are permitted. We don't diagnose array and
  /// function declarators, because they don't allow function types at all.
  ///
  /// The values of this enum are used in diagnostics.
  enum QualifiedFunctionKind { QFK_BlockPointer, QFK_Pointer, QFK_Reference };
  }
  
  /// Check whether the type T is a qualified function type, and if it is,
  /// diagnose that it cannot be contained within the given kind of declarator.
  static bool checkQualifiedFunction(Sema &S, QualType T, SourceLocation Loc,
                                     QualifiedFunctionKind QFK) {
    // Does T refer to a function type with a cv-qualifier or a ref-qualifier?
    const FunctionProtoType *FPT = T->getAs<FunctionProtoType>();
    if (!FPT || (FPT->getTypeQuals() == 0 && FPT->getRefQualifier() == RQ_None))
      return false;
  
    S.Diag(Loc, diag::err_compound_qualified_function_type)
      << QFK << isa<FunctionType>(T.IgnoreParens()) << T
      << getFunctionQualifiersAsString(FPT);
    return true;
  }
  
  /// \brief Build a pointer type.
  ///
  /// \param T The type to which we'll be building a pointer.
  ///
  /// \param Loc The location of the entity whose type involves this
  /// pointer type or, if there is no such entity, the location of the
  /// type that will have pointer type.
  ///
  /// \param Entity The name of the entity that involves the pointer
  /// type, if known.
  ///
  /// \returns A suitable pointer type, if there are no
  /// errors. Otherwise, returns a NULL type.
  QualType Sema::BuildPointerType(QualType T,
                                  SourceLocation Loc, DeclarationName Entity) {
    if (T->isReferenceType()) {
      // C++ 8.3.2p4: There shall be no ... pointers to references ...
      Diag(Loc, diag::err_illegal_decl_pointer_to_reference)
        << getPrintableNameForEntity(Entity) << T;
      return QualType();
    }
  
    if (checkQualifiedFunction(*this, T, Loc, QFK_Pointer))
      return QualType();
  
    assert(!T->isObjCObjectType() && "Should build ObjCObjectPointerType");
  
    // In ARC, it is forbidden to build pointers to unqualified pointers.
    if (getLangOpts().ObjCAutoRefCount)
      T = inferARCLifetimeForPointee(*this, T, Loc, /*reference*/ false);
  
    // Build the pointer type.
    return Context.getPointerType(T);
  }
  
  /// \brief Build a reference type.
  ///
  /// \param T The type to which we'll be building a reference.
  ///
  /// \param Loc The location of the entity whose type involves this
  /// reference type or, if there is no such entity, the location of the
  /// type that will have reference type.
  ///
  /// \param Entity The name of the entity that involves the reference
  /// type, if known.
  ///
  /// \returns A suitable reference type, if there are no
  /// errors. Otherwise, returns a NULL type.
  QualType Sema::BuildReferenceType(QualType T, bool SpelledAsLValue,
                                    SourceLocation Loc,
                                    DeclarationName Entity) {
    assert(Context.getCanonicalType(T) != Context.OverloadTy &&
           "Unresolved overloaded function type");
  
    // C++0x [dcl.ref]p6:
    //   If a typedef (7.1.3), a type template-parameter (14.3.1), or a
    //   decltype-specifier (7.1.6.2) denotes a type TR that is a reference to a
    //   type T, an attempt to create the type "lvalue reference to cv TR" creates
    //   the type "lvalue reference to T", while an attempt to create the type
    //   "rvalue reference to cv TR" creates the type TR.
    bool LValueRef = SpelledAsLValue || T->getAs<LValueReferenceType>();
  
    // C++ [dcl.ref]p4: There shall be no references to references.
    //
    // According to C++ DR 106, references to references are only
    // diagnosed when they are written directly (e.g., "int & &"),
    // but not when they happen via a typedef:
    //
    //   typedef int& intref;
    //   typedef intref& intref2;
    //
    // Parser::ParseDeclaratorInternal diagnoses the case where
    // references are written directly; here, we handle the
    // collapsing of references-to-references as described in C++0x.
    // DR 106 and 540 introduce reference-collapsing into C++98/03.
  
    // C++ [dcl.ref]p1:
    //   A declarator that specifies the type "reference to cv void"
    //   is ill-formed.
    if (T->isVoidType()) {
      Diag(Loc, diag::err_reference_to_void);
      return QualType();
    }
  
    if (checkQualifiedFunction(*this, T, Loc, QFK_Reference))
      return QualType();
  
    // In ARC, it is forbidden to build references to unqualified pointers.
    if (getLangOpts().ObjCAutoRefCount)
      T = inferARCLifetimeForPointee(*this, T, Loc, /*reference*/ true);
  
    // Handle restrict on references.
    if (LValueRef)
      return Context.getLValueReferenceType(T, SpelledAsLValue);
    return Context.getRValueReferenceType(T);
  }
  
  /// Check whether the specified array size makes the array type a VLA.  If so,
  /// return true, if not, return the size of the array in SizeVal.
  static bool isArraySizeVLA(Sema &S, Expr *ArraySize, llvm::APSInt &SizeVal) {
    // If the size is an ICE, it certainly isn't a VLA. If we're in a GNU mode
    // (like gnu99, but not c99) accept any evaluatable value as an extension.
    class VLADiagnoser : public Sema::VerifyICEDiagnoser {
    public:
      VLADiagnoser() : Sema::VerifyICEDiagnoser(true) {}
  
      void diagnoseNotICE(Sema &S, SourceLocation Loc, SourceRange SR) override {
      }
  
      void diagnoseFold(Sema &S, SourceLocation Loc, SourceRange SR) override {
        S.Diag(Loc, diag::ext_vla_folded_to_constant) << SR;
      }
    } Diagnoser;
  
    return S.VerifyIntegerConstantExpression(ArraySize, &SizeVal, Diagnoser,
                                             S.LangOpts.GNUMode).isInvalid();
  }
  
  
  /// \brief Build an array type.
  ///
  /// \param T The type of each element in the array.
  ///
  /// \param ASM C99 array size modifier (e.g., '*', 'static').
  ///
  /// \param ArraySize Expression describing the size of the array.
  ///
  /// \param Brackets The range from the opening '[' to the closing ']'.
  ///
  /// \param Entity The name of the entity that involves the array
  /// type, if known.
  ///
  /// \returns A suitable array type, if there are no errors. Otherwise,
  /// returns a NULL type.
  QualType Sema::BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
                                Expr *ArraySize, unsigned Quals,
                                SourceRange Brackets, DeclarationName Entity) {
  
    SourceLocation Loc = Brackets.getBegin();
    if (getLangOpts().CPlusPlus) {
      // C++ [dcl.array]p1:
      //   T is called the array element type; this type shall not be a reference
      //   type, the (possibly cv-qualified) type void, a function type or an
      //   abstract class type.
      //
      // C++ [dcl.array]p3:
      //   When several "array of" specifications are adjacent, [...] only the
      //   first of the constant expressions that specify the bounds of the arrays
      //   may be omitted.
      //
      // Note: function types are handled in the common path with C.
      if (T->isReferenceType()) {
        Diag(Loc, diag::err_illegal_decl_array_of_references)
        << getPrintableNameForEntity(Entity) << T;
        return QualType();
      }
  
      if (T->isVoidType() || T->isIncompleteArrayType()) {
        Diag(Loc, diag::err_illegal_decl_array_incomplete_type) << T;
        return QualType();
      }
  
      if (RequireNonAbstractType(Brackets.getBegin(), T,
                                 diag::err_array_of_abstract_type))
        return QualType();
  
      // Mentioning a member pointer type for an array type causes us to lock in
      // an inheritance model, even if it's inside an unused typedef.
      if (Context.getTargetInfo().getCXXABI().isMicrosoft())
        if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>())
          if (!MPTy->getClass()->isDependentType())
            RequireCompleteType(Loc, T, 0);
  
    } else {
      // C99 6.7.5.2p1: If the element type is an incomplete or function type,
      // reject it (e.g. void ary[7], struct foo ary[7], void ary[7]())
      if (RequireCompleteType(Loc, T,
                              diag::err_illegal_decl_array_incomplete_type))
        return QualType();
    }
  
    if (T->isFunctionType()) {
      Diag(Loc, diag::err_illegal_decl_array_of_functions)
        << getPrintableNameForEntity(Entity) << T;
      return QualType();
    }
  
    if (const RecordType *EltTy = T->getAs<RecordType>()) {
      // If the element type is a struct or union that contains a variadic
      // array, accept it as a GNU extension: C99 6.7.2.1p2.
      if (EltTy->getDecl()->hasFlexibleArrayMember())
        Diag(Loc, diag::ext_flexible_array_in_array) << T;
    } else if (T->isObjCObjectType()) {
      Diag(Loc, diag::err_objc_array_of_interfaces) << T;
      return QualType();
    }
  
    // Do placeholder conversions on the array size expression.
    if (ArraySize && ArraySize->hasPlaceholderType()) {
      ExprResult Result = CheckPlaceholderExpr(ArraySize);
      if (Result.isInvalid()) return QualType();
      ArraySize = Result.get();
    }
  
    // Do lvalue-to-rvalue conversions on the array size expression.
    if (ArraySize && !ArraySize->isRValue()) {
      ExprResult Result = DefaultLvalueConversion(ArraySize);
      if (Result.isInvalid())
        return QualType();
  
      ArraySize = Result.get();
    }
  
    // C99 6.7.5.2p1: The size expression shall have integer type.
    // C++11 allows contextual conversions to such types.
    if (!getLangOpts().CPlusPlus11 &&
        ArraySize && !ArraySize->isTypeDependent() &&
        !ArraySize->getType()->isIntegralOrUnscopedEnumerationType()) {
      Diag(ArraySize->getLocStart(), diag::err_array_size_non_int)
        << ArraySize->getType() << ArraySize->getSourceRange();
      return QualType();
    }
  
    llvm::APSInt ConstVal(Context.getTypeSize(Context.getSizeType()));
    if (!ArraySize) {
      if (ASM == ArrayType::Star)
        T = Context.getVariableArrayType(T, nullptr, ASM, Quals, Brackets);
      else
        T = Context.getIncompleteArrayType(T, ASM, Quals);
    } else if (ArraySize->isTypeDependent() || ArraySize->isValueDependent()) {
      T = Context.getDependentSizedArrayType(T, ArraySize, ASM, Quals, Brackets);
    } else if ((!T->isDependentType() && !T->isIncompleteType() &&
                !T->isConstantSizeType()) ||
               isArraySizeVLA(*this, ArraySize, ConstVal)) {
      // Even in C++11, don't allow contextual conversions in the array bound
      // of a VLA.
      if (getLangOpts().CPlusPlus11 &&
          !ArraySize->getType()->isIntegralOrUnscopedEnumerationType()) {
        Diag(ArraySize->getLocStart(), diag::err_array_size_non_int)
          << ArraySize->getType() << ArraySize->getSourceRange();
        return QualType();
      }
  
      // C99: an array with an element type that has a non-constant-size is a VLA.
      // C99: an array with a non-ICE size is a VLA.  We accept any expression
      // that we can fold to a non-zero positive value as an extension.
      T = Context.getVariableArrayType(T, ArraySize, ASM, Quals, Brackets);
    } else {
      // C99 6.7.5.2p1: If the expression is a constant expression, it shall
      // have a value greater than zero.
      if (ConstVal.isSigned() && ConstVal.isNegative()) {
        if (Entity)
          Diag(ArraySize->getLocStart(), diag::err_decl_negative_array_size)
            << getPrintableNameForEntity(Entity) << ArraySize->getSourceRange();
        else
          Diag(ArraySize->getLocStart(), diag::err_typecheck_negative_array_size)
            << ArraySize->getSourceRange();
        return QualType();
      }
      if (ConstVal == 0) {
        // GCC accepts zero sized static arrays. We allow them when
        // we're not in a SFINAE context.
        Diag(ArraySize->getLocStart(),
             isSFINAEContext()? diag::err_typecheck_zero_array_size
                              : diag::ext_typecheck_zero_array_size)
          << ArraySize->getSourceRange();
  
        if (ASM == ArrayType::Static) {
          Diag(ArraySize->getLocStart(),
               diag::warn_typecheck_zero_static_array_size)
            << ArraySize->getSourceRange();
          ASM = ArrayType::Normal;
        }
      } else if (!T->isDependentType() && !T->isVariablyModifiedType() &&
                 !T->isIncompleteType() && !T->isUndeducedType()) {
        // Is the array too large?
        unsigned ActiveSizeBits
          = ConstantArrayType::getNumAddressingBits(Context, T, ConstVal);
        if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context)) {
          Diag(ArraySize->getLocStart(), diag::err_array_too_large)
            << ConstVal.toString(10)
            << ArraySize->getSourceRange();
          return QualType();
        }
      }
  
      T = Context.getConstantArrayType(T, ConstVal, ASM, Quals);
    }
  
    // OpenCL v1.2 s6.9.d: variable length arrays are not supported.
    if (getLangOpts().OpenCL && T->isVariableArrayType()) {
      Diag(Loc, diag::err_opencl_vla);
      return QualType();
    }
    // If this is not C99, extwarn about VLA's and C99 array size modifiers.
    if (!getLangOpts().C99) {
      if (T->isVariableArrayType()) {
        // Prohibit the use of non-POD types in VLAs.
        QualType BaseT = Context.getBaseElementType(T);
        if (!T->isDependentType() &&
            !RequireCompleteType(Loc, BaseT, 0) &&
            !BaseT.isPODType(Context) &&
            !BaseT->isObjCLifetimeType()) {
          Diag(Loc, diag::err_vla_non_pod)
            << BaseT;
          return QualType();
        }
        // Prohibit the use of VLAs during template argument deduction.
        else if (isSFINAEContext()) {
          Diag(Loc, diag::err_vla_in_sfinae);
          return QualType();
        }
        // Just extwarn about VLAs.
        else
          Diag(Loc, diag::ext_vla);
      } else if (ASM != ArrayType::Normal || Quals != 0)
        Diag(Loc,
             getLangOpts().CPlusPlus? diag::err_c99_array_usage_cxx
                                       : diag::ext_c99_array_usage) << ASM;
    }
  
    if (T->isVariableArrayType()) {
      // Warn about VLAs for -Wvla.
      Diag(Loc, diag::warn_vla_used);
    }
  
    return T;
  }
  
  /// \brief Build an ext-vector type.
  ///
  /// Run the required checks for the extended vector type.
  QualType Sema::BuildExtVectorType(QualType T, Expr *ArraySize,
                                    SourceLocation AttrLoc) {
    // unlike gcc's vector_size attribute, we do not allow vectors to be defined
    // in conjunction with complex types (pointers, arrays, functions, etc.).
    if (!T->isDependentType() &&
        !T->isIntegerType() && !T->isRealFloatingType()) {
      Diag(AttrLoc, diag::err_attribute_invalid_vector_type) << T;
      return QualType();
    }
  
    if (!ArraySize->isTypeDependent() && !ArraySize->isValueDependent()) {
      llvm::APSInt vecSize(32);
      if (!ArraySize->isIntegerConstantExpr(vecSize, Context)) {
        Diag(AttrLoc, diag::err_attribute_argument_type)
          << "ext_vector_type" << AANT_ArgumentIntegerConstant
          << ArraySize->getSourceRange();
        return QualType();
      }
  
      // unlike gcc's vector_size attribute, the size is specified as the
      // number of elements, not the number of bytes.
      unsigned vectorSize = static_cast<unsigned>(vecSize.getZExtValue());
  
      if (vectorSize == 0) {
        Diag(AttrLoc, diag::err_attribute_zero_size)
        << ArraySize->getSourceRange();
        return QualType();
      }
  
      if (VectorType::isVectorSizeTooLarge(vectorSize)) {
        Diag(AttrLoc, diag::err_attribute_size_too_large)
          << ArraySize->getSourceRange();
        return QualType();
      }
  
      return Context.getExtVectorType(T, vectorSize);
    }
  
    return Context.getDependentSizedExtVectorType(T, ArraySize, AttrLoc);
  }
  
  bool Sema::CheckFunctionReturnType(QualType T, SourceLocation Loc) {
    if (T->isArrayType() || T->isFunctionType()) {
      Diag(Loc, diag::err_func_returning_array_function)
        << T->isFunctionType() << T;
      return true;
    }
  
    // Functions cannot return half FP.
    if (T->isHalfType()) {
      Diag(Loc, diag::err_parameters_retval_cannot_have_fp16_type) << 1 <<
        FixItHint::CreateInsertion(Loc, "*");
      return true;
    }
  
    // Methods cannot return interface types. All ObjC objects are
    // passed by reference.
    if (T->isObjCObjectType()) {
      Diag(Loc, diag::err_object_cannot_be_passed_returned_by_value) << 0 << T;
      return 0;
    }
  
    return false;
  }
  
  QualType Sema::BuildFunctionType(QualType T,
                                   MutableArrayRef<QualType> ParamTypes,
                                   SourceLocation Loc, DeclarationName Entity,
                                   const FunctionProtoType::ExtProtoInfo &EPI) {
    bool Invalid = false;
  
    Invalid |= CheckFunctionReturnType(T, Loc);
  
    for (unsigned Idx = 0, Cnt = ParamTypes.size(); Idx < Cnt; ++Idx) {
      // FIXME: Loc is too inprecise here, should use proper locations for args.
      QualType ParamType = Context.getAdjustedParameterType(ParamTypes[Idx]);
      if (ParamType->isVoidType()) {
        Diag(Loc, diag::err_param_with_void_type);
        Invalid = true;
      } else if (ParamType->isHalfType()) {
        // Disallow half FP arguments.
        Diag(Loc, diag::err_parameters_retval_cannot_have_fp16_type) << 0 <<
          FixItHint::CreateInsertion(Loc, "*");
        Invalid = true;
      }
  
      ParamTypes[Idx] = ParamType;
    }
  
    if (Invalid)
      return QualType();
  
    return Context.getFunctionType(T, ParamTypes, EPI);
  }
  
  /// \brief Build a member pointer type \c T Class::*.
  ///
  /// \param T the type to which the member pointer refers.
  /// \param Class the class type into which the member pointer points.
  /// \param Loc the location where this type begins
  /// \param Entity the name of the entity that will have this member pointer type
  ///
  /// \returns a member pointer type, if successful, or a NULL type if there was
  /// an error.
  QualType Sema::BuildMemberPointerType(QualType T, QualType Class,
                                        SourceLocation Loc,
                                        DeclarationName Entity) {
    // Verify that we're not building a pointer to pointer to function with
    // exception specification.
    if (CheckDistantExceptionSpec(T)) {
      Diag(Loc, diag::err_distant_exception_spec);
  
      // FIXME: If we're doing this as part of template instantiation,
      // we should return immediately.
  
      // Build the type anyway, but use the canonical type so that the
      // exception specifiers are stripped off.
      T = Context.getCanonicalType(T);
    }
  
    // C++ 8.3.3p3: A pointer to member shall not point to ... a member
    //   with reference type, or "cv void."
    if (T->isReferenceType()) {
      Diag(Loc, diag::err_illegal_decl_mempointer_to_reference)
        << getPrintableNameForEntity(Entity) << T;
      return QualType();
    }
  
    if (T->isVoidType()) {
      Diag(Loc, diag::err_illegal_decl_mempointer_to_void)
        << getPrintableNameForEntity(Entity);
      return QualType();
    }
  
    if (!Class->isDependentType() && !Class->isRecordType()) {
      Diag(Loc, diag::err_mempointer_in_nonclass_type) << Class;
      return QualType();
    }
  
    // Adjust the default free function calling convention to the default method
    // calling convention.
    if (T->isFunctionType())
      adjustMemberFunctionCC(T, /*IsStatic=*/false);
  
    return Context.getMemberPointerType(T, Class.getTypePtr());
  }
  
  /// \brief Build a block pointer type.
  ///
  /// \param T The type to which we'll be building a block pointer.
  ///
  /// \param Loc The source location, used for diagnostics.
  ///
  /// \param Entity The name of the entity that involves the block pointer
  /// type, if known.
  ///
  /// \returns A suitable block pointer type, if there are no
  /// errors. Otherwise, returns a NULL type.
  QualType Sema::BuildBlockPointerType(QualType T,
                                       SourceLocation Loc,
                                       DeclarationName Entity) {
    if (!T->isFunctionType()) {
      Diag(Loc, diag::err_nonfunction_block_type);
      return QualType();
    }
  
    if (checkQualifiedFunction(*this, T, Loc, QFK_BlockPointer))
      return QualType();
  
    return Context.getBlockPointerType(T);
  }
  
  QualType Sema::GetTypeFromParser(ParsedType Ty, TypeSourceInfo **TInfo) {
    QualType QT = Ty.get();
    if (QT.isNull()) {
      if (TInfo) *TInfo = nullptr;
      return QualType();
    }
  
    TypeSourceInfo *DI = nullptr;
    if (const LocInfoType *LIT = dyn_cast<LocInfoType>(QT)) {
      QT = LIT->getType();
      DI = LIT->getTypeSourceInfo();
    }
  
    if (TInfo) *TInfo = DI;
    return QT;
  }
  
  static void transferARCOwnershipToDeclaratorChunk(TypeProcessingState &state,
                                              Qualifiers::ObjCLifetime ownership,
                                              unsigned chunkIndex);
  
  /// Given that this is the declaration of a parameter under ARC,
  /// attempt to infer attributes and such for pointer-to-whatever
  /// types.
  static void inferARCWriteback(TypeProcessingState &state,
                                QualType &declSpecType) {
    Sema &S = state.getSema();
    Declarator &declarator = state.getDeclarator();
  
    // TODO: should we care about decl qualifiers?
  
    // Check whether the declarator has the expected form.  We walk
    // from the inside out in order to make the block logic work.
    unsigned outermostPointerIndex = 0;
    bool isBlockPointer = false;
    unsigned numPointers = 0;
    for (unsigned i = 0, e = declarator.getNumTypeObjects(); i != e; ++i) {
      unsigned chunkIndex = i;
      DeclaratorChunk &chunk = declarator.getTypeObject(chunkIndex);
      switch (chunk.Kind) {
      case DeclaratorChunk::Paren:
        // Ignore parens.
        break;
  
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::Pointer:
        // Count the number of pointers.  Treat references
        // interchangeably as pointers; if they're mis-ordered, normal
        // type building will discover that.
        outermostPointerIndex = chunkIndex;
        numPointers++;
        break;
  
      case DeclaratorChunk::BlockPointer:
        // If we have a pointer to block pointer, that's an acceptable
        // indirect reference; anything else is not an application of
        // the rules.
        if (numPointers != 1) return;
        numPointers++;
        outermostPointerIndex = chunkIndex;
        isBlockPointer = true;
  
        // We don't care about pointer structure in return values here.
        goto done;
  
      case DeclaratorChunk::Array: // suppress if written (id[])?
      case DeclaratorChunk::Function:
      case DeclaratorChunk::MemberPointer:
        return;
      }
    }
   done:
  
    // If we have *one* pointer, then we want to throw the qualifier on
    // the declaration-specifiers, which means that it needs to be a
    // retainable object type.
    if (numPointers == 1) {
      // If it's not a retainable object type, the rule doesn't apply.
      if (!declSpecType->isObjCRetainableType()) return;
  
      // If it already has lifetime, don't do anything.
      if (declSpecType.getObjCLifetime()) return;
  
      // Otherwise, modify the type in-place.
      Qualifiers qs;
  
      if (declSpecType->isObjCARCImplicitlyUnretainedType())
        qs.addObjCLifetime(Qualifiers::OCL_ExplicitNone);
      else
        qs.addObjCLifetime(Qualifiers::OCL_Autoreleasing);
      declSpecType = S.Context.getQualifiedType(declSpecType, qs);
  
    // If we have *two* pointers, then we want to throw the qualifier on
    // the outermost pointer.
    } else if (numPointers == 2) {
      // If we don't have a block pointer, we need to check whether the
      // declaration-specifiers gave us something that will turn into a
      // retainable object pointer after we slap the first pointer on it.
      if (!isBlockPointer && !declSpecType->isObjCObjectType())
        return;
  
      // Look for an explicit lifetime attribute there.
      DeclaratorChunk &chunk = declarator.getTypeObject(outermostPointerIndex);
      if (chunk.Kind != DeclaratorChunk::Pointer &&
          chunk.Kind != DeclaratorChunk::BlockPointer)
        return;
      for (const AttributeList *attr = chunk.getAttrs(); attr;
             attr = attr->getNext())
        if (attr->getKind() == AttributeList::AT_ObjCOwnership)
          return;
  
      transferARCOwnershipToDeclaratorChunk(state, Qualifiers::OCL_Autoreleasing,
                                            outermostPointerIndex);
  
    // Any other number of pointers/references does not trigger the rule.
    } else return;
  
    // TODO: mark whether we did this inference?
  }
  
  void Sema::diagnoseIgnoredQualifiers(unsigned DiagID, unsigned Quals,
                                       SourceLocation FallbackLoc,
                                       SourceLocation ConstQualLoc,
                                       SourceLocation VolatileQualLoc,
                                       SourceLocation RestrictQualLoc,
                                       SourceLocation AtomicQualLoc) {
    if (!Quals)
      return;
  
    struct Qual {
      unsigned Mask;
      const char *Name;
      SourceLocation Loc;
    } const QualKinds[4] = {
      { DeclSpec::TQ_const, "const", ConstQualLoc },
      { DeclSpec::TQ_volatile, "volatile", VolatileQualLoc },
      { DeclSpec::TQ_restrict, "restrict", RestrictQualLoc },
      { DeclSpec::TQ_atomic, "_Atomic", AtomicQualLoc }
    };
  
    SmallString<32> QualStr;
    unsigned NumQuals = 0;
    SourceLocation Loc;
    FixItHint FixIts[4];
  
    // Build a string naming the redundant qualifiers.
    for (unsigned I = 0; I != 4; ++I) {
      if (Quals & QualKinds[I].Mask) {
        if (!QualStr.empty()) QualStr += ' ';
        QualStr += QualKinds[I].Name;
  
        // If we have a location for the qualifier, offer a fixit.
        SourceLocation QualLoc = QualKinds[I].Loc;
        if (!QualLoc.isInvalid()) {
          FixIts[NumQuals] = FixItHint::CreateRemoval(QualLoc);
          if (Loc.isInvalid() ||
              getSourceManager().isBeforeInTranslationUnit(QualLoc, Loc))
            Loc = QualLoc;
        }
  
        ++NumQuals;
      }
    }
  
    Diag(Loc.isInvalid() ? FallbackLoc : Loc, DiagID)
      << QualStr << NumQuals << FixIts[0] << FixIts[1] << FixIts[2] << FixIts[3];
  }
  
  // Diagnose pointless type qualifiers on the return type of a function.
  static void diagnoseRedundantReturnTypeQualifiers(Sema &S, QualType RetTy,
                                                    Declarator &D,
                                                    unsigned FunctionChunkIndex) {
    if (D.getTypeObject(FunctionChunkIndex).Fun.hasTrailingReturnType()) {
      // FIXME: TypeSourceInfo doesn't preserve location information for
      // qualifiers.
      S.diagnoseIgnoredQualifiers(diag::warn_qual_return_type,
                                  RetTy.getLocalCVRQualifiers(),
                                  D.getIdentifierLoc());
      return;
    }
  
    for (unsigned OuterChunkIndex = FunctionChunkIndex + 1,
                  End = D.getNumTypeObjects();
         OuterChunkIndex != End; ++OuterChunkIndex) {
      DeclaratorChunk &OuterChunk = D.getTypeObject(OuterChunkIndex);
      switch (OuterChunk.Kind) {
      case DeclaratorChunk::Paren:
        continue;
  
      case DeclaratorChunk::Pointer: {
        DeclaratorChunk::PointerTypeInfo &PTI = OuterChunk.Ptr;
        S.diagnoseIgnoredQualifiers(
            diag::warn_qual_return_type,
            PTI.TypeQuals,
            SourceLocation(),
            SourceLocation::getFromRawEncoding(PTI.ConstQualLoc),
            SourceLocation::getFromRawEncoding(PTI.VolatileQualLoc),
            SourceLocation::getFromRawEncoding(PTI.RestrictQualLoc),
            SourceLocation::getFromRawEncoding(PTI.AtomicQualLoc));
        return;
      }
  
      case DeclaratorChunk::Function:
      case DeclaratorChunk::BlockPointer:
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::Array:
      case DeclaratorChunk::MemberPointer:
        // FIXME: We can't currently provide an accurate source location and a
        // fix-it hint for these.
        unsigned AtomicQual = RetTy->isAtomicType() ? DeclSpec::TQ_atomic : 0;
        S.diagnoseIgnoredQualifiers(diag::warn_qual_return_type,
                                    RetTy.getCVRQualifiers() | AtomicQual,
                                    D.getIdentifierLoc());
        return;
      }
  
      llvm_unreachable("unknown declarator chunk kind");
    }
  
    // If the qualifiers come from a conversion function type, don't diagnose
    // them -- they're not necessarily redundant, since such a conversion
    // operator can be explicitly called as "x.operator const int()".
    if (D.getName().getKind() == UnqualifiedId::IK_ConversionFunctionId)
      return;
  
    // Just parens all the way out to the decl specifiers. Diagnose any qualifiers
    // which are present there.
    S.diagnoseIgnoredQualifiers(diag::warn_qual_return_type,
                                D.getDeclSpec().getTypeQualifiers(),
                                D.getIdentifierLoc(),
                                D.getDeclSpec().getConstSpecLoc(),
                                D.getDeclSpec().getVolatileSpecLoc(),
                                D.getDeclSpec().getRestrictSpecLoc(),
                                D.getDeclSpec().getAtomicSpecLoc());
  }
  
  static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
                                               TypeSourceInfo *&ReturnTypeInfo) {
    Sema &SemaRef = state.getSema();
    Declarator &D = state.getDeclarator();
    QualType T;
    ReturnTypeInfo = nullptr;
  
    // The TagDecl owned by the DeclSpec.
    TagDecl *OwnedTagDecl = nullptr;
  
    bool ContainsPlaceholderType = false;
  
    switch (D.getName().getKind()) {
    case UnqualifiedId::IK_ImplicitSelfParam:
    case UnqualifiedId::IK_OperatorFunctionId:
    case UnqualifiedId::IK_Identifier:
    case UnqualifiedId::IK_LiteralOperatorId:
    case UnqualifiedId::IK_TemplateId:
      T = ConvertDeclSpecToType(state);
      ContainsPlaceholderType = D.getDeclSpec().containsPlaceholderType();
  
      if (!D.isInvalidType() && D.getDeclSpec().isTypeSpecOwned()) {
        OwnedTagDecl = cast<TagDecl>(D.getDeclSpec().getRepAsDecl());
        // Owned declaration is embedded in declarator.
        OwnedTagDecl->setEmbeddedInDeclarator(true);
      }
      break;
  
    case UnqualifiedId::IK_ConstructorName:
    case UnqualifiedId::IK_ConstructorTemplateId:
    case UnqualifiedId::IK_DestructorName:
      // Constructors and destructors don't have return types. Use
      // "void" instead.
      T = SemaRef.Context.VoidTy;
      if (AttributeList *attrs = D.getDeclSpec().getAttributes().getList())
        processTypeAttrs(state, T, TAL_DeclSpec, attrs);
      break;
  
    case UnqualifiedId::IK_ConversionFunctionId:
      // The result type of a conversion function is the type that it
      // converts to.
      T = SemaRef.GetTypeFromParser(D.getName().ConversionFunctionId,
                                    &ReturnTypeInfo);
      ContainsPlaceholderType = T->getContainedAutoType();
      break;
    }
  
    if (D.getAttributes())
      distributeTypeAttrsFromDeclarator(state, T);
  
    // C++11 [dcl.spec.auto]p5: reject 'auto' if it is not in an allowed context.
    // In C++11, a function declarator using 'auto' must have a trailing return
    // type (this is checked later) and we can skip this. In other languages
    // using auto, we need to check regardless.
    // C++14 In generic lambdas allow 'auto' in their parameters.
    if (ContainsPlaceholderType &&
        (!SemaRef.getLangOpts().CPlusPlus11 || !D.isFunctionDeclarator())) {
      int Error = -1;
  
      switch (D.getContext()) {
      case Declarator::KNRTypeListContext:
        llvm_unreachable("K&R type lists aren't allowed in C++");
      case Declarator::LambdaExprContext:
        llvm_unreachable("Can't specify a type specifier in lambda grammar");
      case Declarator::ObjCParameterContext:
      case Declarator::ObjCResultContext:
      case Declarator::PrototypeContext:
        Error = 0;  
        break;
      case Declarator::LambdaExprParameterContext:
        if (!(SemaRef.getLangOpts().CPlusPlus1y 
                && D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto))
          Error = 14;
        break;
      case Declarator::MemberContext:
        if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static)
          break;
        switch (cast<TagDecl>(SemaRef.CurContext)->getTagKind()) {
        case TTK_Enum: llvm_unreachable("unhandled tag kind");
        case TTK_Struct: Error = 1; /* Struct member */ break;
        case TTK_Union:  Error = 2; /* Union member */ break;
        case TTK_Class:  Error = 3; /* Class member */ break;
        case TTK_Interface: Error = 4; /* Interface member */ break;
        }
        break;
      case Declarator::CXXCatchContext:
      case Declarator::ObjCCatchContext:
        Error = 5; // Exception declaration
        break;
      case Declarator::TemplateParamContext:
        Error = 6; // Template parameter
        break;
      case Declarator::BlockLiteralContext:
        Error = 7; // Block literal
        break;
      case Declarator::TemplateTypeArgContext:
        Error = 8; // Template type argument
        break;
      case Declarator::AliasDeclContext:
      case Declarator::AliasTemplateContext:
        Error = 10; // Type alias
        break;
      case Declarator::TrailingReturnContext:
        if (!SemaRef.getLangOpts().CPlusPlus1y)
          Error = 11; // Function return type
        break;
      case Declarator::ConversionIdContext:
        if (!SemaRef.getLangOpts().CPlusPlus1y)
          Error = 12; // conversion-type-id
        break;
      case Declarator::TypeNameContext:
        Error = 13; // Generic
        break;
      case Declarator::FileContext:
      case Declarator::BlockContext:
      case Declarator::ForContext:
      case Declarator::ConditionContext:
      case Declarator::CXXNewContext:
        break;
      }
  
      if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef)
        Error = 9;
  
      // In Objective-C it is an error to use 'auto' on a function declarator.
      if (D.isFunctionDeclarator())
        Error = 11;
  
      // C++11 [dcl.spec.auto]p2: 'auto' is always fine if the declarator
      // contains a trailing return type. That is only legal at the outermost
      // level. Check all declarator chunks (outermost first) anyway, to give
      // better diagnostics.
      if (SemaRef.getLangOpts().CPlusPlus11 && Error != -1) {
        for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
          unsigned chunkIndex = e - i - 1;
          state.setCurrentChunkIndex(chunkIndex);
          DeclaratorChunk &DeclType = D.getTypeObject(chunkIndex);
          if (DeclType.Kind == DeclaratorChunk::Function) {
            const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
            if (FTI.hasTrailingReturnType()) {
              Error = -1;
              break;
            }
          }
        }
      }
  
      SourceRange AutoRange = D.getDeclSpec().getTypeSpecTypeLoc();
      if (D.getName().getKind() == UnqualifiedId::IK_ConversionFunctionId)
        AutoRange = D.getName().getSourceRange();
  
      if (Error != -1) {
        const bool IsDeclTypeAuto = 
            D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_decltype_auto;
        SemaRef.Diag(AutoRange.getBegin(), diag::err_auto_not_allowed)
          << IsDeclTypeAuto << Error << AutoRange;
        T = SemaRef.Context.IntTy;
        D.setInvalidType(true);
      } else
        SemaRef.Diag(AutoRange.getBegin(),
                     diag::warn_cxx98_compat_auto_type_specifier)
          << AutoRange;
    }
  
    if (SemaRef.getLangOpts().CPlusPlus &&
        OwnedTagDecl && OwnedTagDecl->isCompleteDefinition()) {
      // Check the contexts where C++ forbids the declaration of a new class
      // or enumeration in a type-specifier-seq.
      switch (D.getContext()) {
      case Declarator::TrailingReturnContext:
        // Class and enumeration definitions are syntactically not allowed in
        // trailing return types.
        llvm_unreachable("parser should not have allowed this");
        break;
      case Declarator::FileContext:
      case Declarator::MemberContext:
      case Declarator::BlockContext:
      case Declarator::ForContext:
      case Declarator::BlockLiteralContext:
      case Declarator::LambdaExprContext:
        // C++11 [dcl.type]p3:
        //   A type-specifier-seq shall not define a class or enumeration unless
        //   it appears in the type-id of an alias-declaration (7.1.3) that is not
        //   the declaration of a template-declaration.
      case Declarator::AliasDeclContext:
        break;
      case Declarator::AliasTemplateContext:
        SemaRef.Diag(OwnedTagDecl->getLocation(),
               diag::err_type_defined_in_alias_template)
          << SemaRef.Context.getTypeDeclType(OwnedTagDecl);
        D.setInvalidType(true);
        break;
      case Declarator::TypeNameContext:
      case Declarator::ConversionIdContext:
      case Declarator::TemplateParamContext:
      case Declarator::CXXNewContext:
      case Declarator::CXXCatchContext:
      case Declarator::ObjCCatchContext:
      case Declarator::TemplateTypeArgContext:
        SemaRef.Diag(OwnedTagDecl->getLocation(),
               diag::err_type_defined_in_type_specifier)
          << SemaRef.Context.getTypeDeclType(OwnedTagDecl);
        D.setInvalidType(true);
        break;
      case Declarator::PrototypeContext:
      case Declarator::LambdaExprParameterContext:
      case Declarator::ObjCParameterContext:
      case Declarator::ObjCResultContext:
      case Declarator::KNRTypeListContext:
        // C++ [dcl.fct]p6:
        //   Types shall not be defined in return or parameter types.
        SemaRef.Diag(OwnedTagDecl->getLocation(),
                     diag::err_type_defined_in_param_type)
          << SemaRef.Context.getTypeDeclType(OwnedTagDecl);
        D.setInvalidType(true);
        break;
      case Declarator::ConditionContext:
        // C++ 6.4p2:
        // The type-specifier-seq shall not contain typedef and shall not declare
        // a new class or enumeration.
        SemaRef.Diag(OwnedTagDecl->getLocation(),
                     diag::err_type_defined_in_condition);
        D.setInvalidType(true);
        break;
      }
    }
  
    return T;
  }
  
  /// Produce an appropriate diagnostic for an ambiguity between a function
  /// declarator and a C++ direct-initializer.
  static void warnAboutAmbiguousFunction(Sema &S, Declarator &D,
                                         DeclaratorChunk &DeclType, QualType RT) {
    const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
    assert(FTI.isAmbiguous && "no direct-initializer / function ambiguity");
  
    // If the return type is void there is no ambiguity.
    if (RT->isVoidType())
      return;
  
    // An initializer for a non-class type can have at most one argument.
    if (!RT->isRecordType() && FTI.NumParams > 1)
      return;
  
    // An initializer for a reference must have exactly one argument.
    if (RT->isReferenceType() && FTI.NumParams != 1)
      return;
  
    // Only warn if this declarator is declaring a function at block scope, and
    // doesn't have a storage class (such as 'extern') specified.
    if (!D.isFunctionDeclarator() ||
        D.getFunctionDefinitionKind() != FDK_Declaration ||
        !S.CurContext->isFunctionOrMethod() ||
        D.getDeclSpec().getStorageClassSpec()
          != DeclSpec::SCS_unspecified)
      return;
  
    // Inside a condition, a direct initializer is not permitted. We allow one to
    // be parsed in order to give better diagnostics in condition parsing.
    if (D.getContext() == Declarator::ConditionContext)
      return;
  
    SourceRange ParenRange(DeclType.Loc, DeclType.EndLoc);
  
    S.Diag(DeclType.Loc,
           FTI.NumParams ? diag::warn_parens_disambiguated_as_function_declaration
                         : diag::warn_empty_parens_are_function_decl)
        << ParenRange;
  
    // If the declaration looks like:
    //   T var1,
    //   f();
    // and name lookup finds a function named 'f', then the ',' was
    // probably intended to be a ';'.
    if (!D.isFirstDeclarator() && D.getIdentifier()) {
      FullSourceLoc Comma(D.getCommaLoc(), S.SourceMgr);
      FullSourceLoc Name(D.getIdentifierLoc(), S.SourceMgr);
      if (Comma.getFileID() != Name.getFileID() ||
          Comma.getSpellingLineNumber() != Name.getSpellingLineNumber()) {
        LookupResult Result(S, D.getIdentifier(), SourceLocation(),
                            Sema::LookupOrdinaryName);
        if (S.LookupName(Result, S.getCurScope()))
          S.Diag(D.getCommaLoc(), diag::note_empty_parens_function_call)
            << FixItHint::CreateReplacement(D.getCommaLoc(), ";")
            << D.getIdentifier();
      }
    }
  
    if (FTI.NumParams > 0) {
      // For a declaration with parameters, eg. "T var(T());", suggest adding
      // parens around the first parameter to turn the declaration into a
      // variable declaration.
      SourceRange Range = FTI.Params[0].Param->getSourceRange();
      SourceLocation B = Range.getBegin();
      SourceLocation E = S.getLocForEndOfToken(Range.getEnd());
      // FIXME: Maybe we should suggest adding braces instead of parens
      // in C++11 for classes that don't have an initializer_list constructor.
      S.Diag(B, diag::note_additional_parens_for_variable_declaration)
        << FixItHint::CreateInsertion(B, "(")
        << FixItHint::CreateInsertion(E, ")");
    } else {
      // For a declaration without parameters, eg. "T var();", suggest replacing
      // the parens with an initializer to turn the declaration into a variable
      // declaration.
      const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
  
      // Empty parens mean value-initialization, and no parens mean
      // default initialization. These are equivalent if the default
      // constructor is user-provided or if zero-initialization is a
      // no-op.
      if (RD && RD->hasDefinition() &&
          (RD->isEmpty() || RD->hasUserProvidedDefaultConstructor()))
        S.Diag(DeclType.Loc, diag::note_empty_parens_default_ctor)
          << FixItHint::CreateRemoval(ParenRange);
      else {
        std::string Init =
            S.getFixItZeroInitializerForType(RT, ParenRange.getBegin());
        if (Init.empty() && S.LangOpts.CPlusPlus11)
          Init = "{}";
        if (!Init.empty())
          S.Diag(DeclType.Loc, diag::note_empty_parens_zero_initialize)
            << FixItHint::CreateReplacement(ParenRange, Init);
      }
    }
  }
  
  /// Helper for figuring out the default CC for a function declarator type.  If
  /// this is the outermost chunk, then we can determine the CC from the
  /// declarator context.  If not, then this could be either a member function
  /// type or normal function type.
  static CallingConv
  getCCForDeclaratorChunk(Sema &S, Declarator &D,
                          const DeclaratorChunk::FunctionTypeInfo &FTI,
                          unsigned ChunkIndex) {
    assert(D.getTypeObject(ChunkIndex).Kind == DeclaratorChunk::Function);
  
    bool IsCXXInstanceMethod = false;
  
    if (S.getLangOpts().CPlusPlus) {
      // Look inwards through parentheses to see if this chunk will form a
      // member pointer type or if we're the declarator.  Any type attributes
      // between here and there will override the CC we choose here.
      unsigned I = ChunkIndex;
      bool FoundNonParen = false;
      while (I && !FoundNonParen) {
        --I;
        if (D.getTypeObject(I).Kind != DeclaratorChunk::Paren)
          FoundNonParen = true;
      }
  
      if (FoundNonParen) {
        // If we're not the declarator, we're a regular function type unless we're
        // in a member pointer.
        IsCXXInstanceMethod =
            D.getTypeObject(I).Kind == DeclaratorChunk::MemberPointer;
      } else {
        // We're the innermost decl chunk, so must be a function declarator.
        assert(D.isFunctionDeclarator());
  
        // If we're inside a record, we're declaring a method, but it could be
        // explicitly or implicitly static.
        IsCXXInstanceMethod =
            D.isFirstDeclarationOfMember() &&
            D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_typedef &&
            !D.isStaticMember();
      }
    }
  
    return S.Context.getDefaultCallingConvention(FTI.isVariadic,
                                                 IsCXXInstanceMethod);
  }
  
  static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
                                                  QualType declSpecType,
                                                  TypeSourceInfo *TInfo) {
  
    QualType T = declSpecType;
    Declarator &D = state.getDeclarator();
    Sema &S = state.getSema();
    ASTContext &Context = S.Context;
    const LangOptions &LangOpts = S.getLangOpts();
  
    // The name we're declaring, if any.
    DeclarationName Name;
    if (D.getIdentifier())
      Name = D.getIdentifier();
  
    // Does this declaration declare a typedef-name?
    bool IsTypedefName =
      D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef ||
      D.getContext() == Declarator::AliasDeclContext ||
      D.getContext() == Declarator::AliasTemplateContext;
  
    // Does T refer to a function type with a cv-qualifier or a ref-qualifier?
    bool IsQualifiedFunction = T->isFunctionProtoType() &&
        (T->castAs<FunctionProtoType>()->getTypeQuals() != 0 ||
         T->castAs<FunctionProtoType>()->getRefQualifier() != RQ_None);
  
    // If T is 'decltype(auto)', the only declarators we can have are parens
    // and at most one function declarator if this is a function declaration.
    if (const AutoType *AT = T->getAs<AutoType>()) {
      if (AT->isDecltypeAuto()) {
        for (unsigned I = 0, E = D.getNumTypeObjects(); I != E; ++I) {
          unsigned Index = E - I - 1;
          DeclaratorChunk &DeclChunk = D.getTypeObject(Index);
          unsigned DiagId = diag::err_decltype_auto_compound_type;
          unsigned DiagKind = 0;
          switch (DeclChunk.Kind) {
          case DeclaratorChunk::Paren:
            continue;
          case DeclaratorChunk::Function: {
            unsigned FnIndex;
            if (D.isFunctionDeclarationContext() &&
                D.isFunctionDeclarator(FnIndex) && FnIndex == Index)
              continue;
            DiagId = diag::err_decltype_auto_function_declarator_not_declaration;
            break;
          }
          case DeclaratorChunk::Pointer:
          case DeclaratorChunk::BlockPointer:
          case DeclaratorChunk::MemberPointer:
            DiagKind = 0;
            break;
          case DeclaratorChunk::Reference:
            DiagKind = 1;
            break;
          case DeclaratorChunk::Array:
            DiagKind = 2;
            break;
          }
  
          S.Diag(DeclChunk.Loc, DiagId) << DiagKind;
          D.setInvalidType(true);
          break;
        }
      }
    }
  
    // Walk the DeclTypeInfo, building the recursive type as we go.
    // DeclTypeInfos are ordered from the identifier out, which is
    // opposite of what we want :).
    for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
      unsigned chunkIndex = e - i - 1;
      state.setCurrentChunkIndex(chunkIndex);
      DeclaratorChunk &DeclType = D.getTypeObject(chunkIndex);
      IsQualifiedFunction &= DeclType.Kind == DeclaratorChunk::Paren;
      switch (DeclType.Kind) {
      case DeclaratorChunk::Paren:
        T = S.BuildParenType(T);
        break;
      case DeclaratorChunk::BlockPointer:
        // If blocks are disabled, emit an error.
        if (!LangOpts.Blocks)
          S.Diag(DeclType.Loc, diag::err_blocks_disable);
  
        T = S.BuildBlockPointerType(T, D.getIdentifierLoc(), Name);
        if (DeclType.Cls.TypeQuals)
          T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Cls.TypeQuals);
        break;
      case DeclaratorChunk::Pointer:
        // Verify that we're not building a pointer to pointer to function with
        // exception specification.
        if (LangOpts.CPlusPlus && S.CheckDistantExceptionSpec(T)) {
          S.Diag(D.getIdentifierLoc(), diag::err_distant_exception_spec);
          D.setInvalidType(true);
          // Build the type anyway.
        }
        if (LangOpts.ObjC1 && T->getAs<ObjCObjectType>()) {
          T = Context.getObjCObjectPointerType(T);
          if (DeclType.Ptr.TypeQuals)
            T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Ptr.TypeQuals);
          break;
        }
        T = S.BuildPointerType(T, DeclType.Loc, Name);
        if (DeclType.Ptr.TypeQuals)
          T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Ptr.TypeQuals);
  
        break;
      case DeclaratorChunk::Reference: {
        // Verify that we're not building a reference to pointer to function with
        // exception specification.
        if (LangOpts.CPlusPlus && S.CheckDistantExceptionSpec(T)) {
          S.Diag(D.getIdentifierLoc(), diag::err_distant_exception_spec);
          D.setInvalidType(true);
          // Build the type anyway.
        }
        T = S.BuildReferenceType(T, DeclType.Ref.LValueRef, DeclType.Loc, Name);
  
        if (DeclType.Ref.HasRestrict)
          T = S.BuildQualifiedType(T, DeclType.Loc, Qualifiers::Restrict);
        break;
      }
      case DeclaratorChunk::Array: {
        // Verify that we're not building an array of pointers to function with
        // exception specification.
        if (LangOpts.CPlusPlus && S.CheckDistantExceptionSpec(T)) {
          S.Diag(D.getIdentifierLoc(), diag::err_distant_exception_spec);
          D.setInvalidType(true);
          // Build the type anyway.
        }
        DeclaratorChunk::ArrayTypeInfo &ATI = DeclType.Arr;
        Expr *ArraySize = static_cast<Expr*>(ATI.NumElts);
        ArrayType::ArraySizeModifier ASM;
        if (ATI.isStar)
          ASM = ArrayType::Star;
        else if (ATI.hasStatic)
          ASM = ArrayType::Static;
        else
          ASM = ArrayType::Normal;
        if (ASM == ArrayType::Star && !D.isPrototypeContext()) {
          // FIXME: This check isn't quite right: it allows star in prototypes
          // for function definitions, and disallows some edge cases detailed
          // in http://gcc.gnu.org/ml/gcc-patches/2009-02/msg00133.html
          S.Diag(DeclType.Loc, diag::err_array_star_outside_prototype);
          ASM = ArrayType::Normal;
          D.setInvalidType(true);
        }
  
        // C99 6.7.5.2p1: The optional type qualifiers and the keyword static
        // shall appear only in a declaration of a function parameter with an
        // array type, ...
        if (ASM == ArrayType::Static || ATI.TypeQuals) {
          if (!(D.isPrototypeContext() ||
                D.getContext() == Declarator::KNRTypeListContext)) {
            S.Diag(DeclType.Loc, diag::err_array_static_outside_prototype) <<
                (ASM == ArrayType::Static ? "'static'" : "type qualifier");
            // Remove the 'static' and the type qualifiers.
            if (ASM == ArrayType::Static)
              ASM = ArrayType::Normal;
            ATI.TypeQuals = 0;
            D.setInvalidType(true);
          }
  
          // C99 6.7.5.2p1: ... and then only in the outermost array type
          // derivation.
          unsigned x = chunkIndex;
          while (x != 0) {
            // Walk outwards along the declarator chunks.
            x--;
            const DeclaratorChunk &DC = D.getTypeObject(x);
            switch (DC.Kind) {
            case DeclaratorChunk::Paren:
              continue;
            case DeclaratorChunk::Array:
            case DeclaratorChunk::Pointer:
            case DeclaratorChunk::Reference:
            case DeclaratorChunk::MemberPointer:
              S.Diag(DeclType.Loc, diag::err_array_static_not_outermost) <<
                (ASM == ArrayType::Static ? "'static'" : "type qualifier");
              if (ASM == ArrayType::Static)
                ASM = ArrayType::Normal;
              ATI.TypeQuals = 0;
              D.setInvalidType(true);
              break;
            case DeclaratorChunk::Function:
            case DeclaratorChunk::BlockPointer:
              // These are invalid anyway, so just ignore.
              break;
            }
          }
        }
        const AutoType *AT = T->getContainedAutoType();
        // Allow arrays of auto if we are a generic lambda parameter.
        // i.e. [](auto (&array)[5]) { return array[0]; }; OK
        if (AT && D.getContext() != Declarator::LambdaExprParameterContext) {
          // We've already diagnosed this for decltype(auto).
          if (!AT->isDecltypeAuto())
            S.Diag(DeclType.Loc, diag::err_illegal_decl_array_of_auto)
              << getPrintableNameForEntity(Name) << T;
          T = QualType();
          break;
        }
  
        T = S.BuildArrayType(T, ASM, ArraySize, ATI.TypeQuals,
                             SourceRange(DeclType.Loc, DeclType.EndLoc), Name);
        break;
      }
      case DeclaratorChunk::Function: {
        // If the function declarator has a prototype (i.e. it is not () and
        // does not have a K&R-style identifier list), then the arguments are part
        // of the type, otherwise the argument list is ().
        const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
        IsQualifiedFunction = FTI.TypeQuals || FTI.hasRefQualifier();
  
        // Check for auto functions and trailing return type and adjust the
        // return type accordingly.
        if (!D.isInvalidType()) {
          // trailing-return-type is only required if we're declaring a function,
          // and not, for instance, a pointer to a function.
          if (D.getDeclSpec().containsPlaceholderType() &&
              !FTI.hasTrailingReturnType() && chunkIndex == 0 &&
              !S.getLangOpts().CPlusPlus1y) {
            S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
                   D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto
                       ? diag::err_auto_missing_trailing_return
                       : diag::err_deduced_return_type);
            T = Context.IntTy;
            D.setInvalidType(true);
          } else if (FTI.hasTrailingReturnType()) {
            // T must be exactly 'auto' at this point. See CWG issue 681.
            if (isa<ParenType>(T)) {
              S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
                   diag::err_trailing_return_in_parens)
                << T << D.getDeclSpec().getSourceRange();
              D.setInvalidType(true);
            } else if (D.getContext() != Declarator::LambdaExprContext &&
                       (T.hasQualifiers() || !isa<AutoType>(T) ||
                        cast<AutoType>(T)->isDecltypeAuto())) {
              S.Diag(D.getDeclSpec().getTypeSpecTypeLoc(),
                   diag::err_trailing_return_without_auto)
                << T << D.getDeclSpec().getSourceRange();
              D.setInvalidType(true);
            }
            T = S.GetTypeFromParser(FTI.getTrailingReturnType(), &TInfo);
            if (T.isNull()) {
              // An error occurred parsing the trailing return type.
              T = Context.IntTy;
              D.setInvalidType(true);
            }
          }
        }
  
        // C99 6.7.5.3p1: The return type may not be a function or array type.
        // For conversion functions, we'll diagnose this particular error later.
        if ((T->isArrayType() || T->isFunctionType()) &&
            (D.getName().getKind() != UnqualifiedId::IK_ConversionFunctionId)) {
          unsigned diagID = diag::err_func_returning_array_function;
          // Last processing chunk in block context means this function chunk
          // represents the block.
          if (chunkIndex == 0 &&
              D.getContext() == Declarator::BlockLiteralContext)
            diagID = diag::err_block_returning_array_function;
          S.Diag(DeclType.Loc, diagID) << T->isFunctionType() << T;
          T = Context.IntTy;
          D.setInvalidType(true);
        }
  
        // Do not allow returning half FP value.
        // FIXME: This really should be in BuildFunctionType.
        if (T->isHalfType()) {
          if (S.getLangOpts().OpenCL) {
            if (!S.getOpenCLOptions().cl_khr_fp16) {
              S.Diag(D.getIdentifierLoc(), diag::err_opencl_half_return) << T;
              D.setInvalidType(true);
            } 
          } else {
            S.Diag(D.getIdentifierLoc(),
              diag::err_parameters_retval_cannot_have_fp16_type) << 1;
            D.setInvalidType(true);
          }
        }
  
        // Methods cannot return interface types. All ObjC objects are
        // passed by reference.
        if (T->isObjCObjectType()) {
          SourceLocation DiagLoc, FixitLoc;
          if (TInfo) {
            DiagLoc = TInfo->getTypeLoc().getLocStart();
            FixitLoc = S.getLocForEndOfToken(TInfo->getTypeLoc().getLocEnd());
          } else {
            DiagLoc = D.getDeclSpec().getTypeSpecTypeLoc();
            FixitLoc = S.getLocForEndOfToken(D.getDeclSpec().getLocEnd());
          }
          S.Diag(DiagLoc, diag::err_object_cannot_be_passed_returned_by_value)
            << 0 << T
            << FixItHint::CreateInsertion(FixitLoc, "*");
  
          T = Context.getObjCObjectPointerType(T);
          if (TInfo) {
            TypeLocBuilder TLB;
            TLB.pushFullCopy(TInfo->getTypeLoc());
            ObjCObjectPointerTypeLoc TLoc = TLB.push<ObjCObjectPointerTypeLoc>(T);
            TLoc.setStarLoc(FixitLoc);
            TInfo = TLB.getTypeSourceInfo(Context, T);
          }
  
          D.setInvalidType(true);
        }
  
        // cv-qualifiers on return types are pointless except when the type is a
        // class type in C++.
        if ((T.getCVRQualifiers() || T->isAtomicType()) &&
            !(S.getLangOpts().CPlusPlus &&
              (T->isDependentType() || T->isRecordType())))
          diagnoseRedundantReturnTypeQualifiers(S, T, D, chunkIndex);
  
        // Objective-C ARC ownership qualifiers are ignored on the function
        // return type (by type canonicalization). Complain if this attribute
        // was written here.
        if (T.getQualifiers().hasObjCLifetime()) {
          SourceLocation AttrLoc;
          if (chunkIndex + 1 < D.getNumTypeObjects()) {
            DeclaratorChunk ReturnTypeChunk = D.getTypeObject(chunkIndex + 1);
            for (const AttributeList *Attr = ReturnTypeChunk.getAttrs();
                 Attr; Attr = Attr->getNext()) {
              if (Attr->getKind() == AttributeList::AT_ObjCOwnership) {
                AttrLoc = Attr->getLoc();
                break;
              }
            }
          }
          if (AttrLoc.isInvalid()) {
            for (const AttributeList *Attr
                   = D.getDeclSpec().getAttributes().getList();
                 Attr; Attr = Attr->getNext()) {
              if (Attr->getKind() == AttributeList::AT_ObjCOwnership) {
                AttrLoc = Attr->getLoc();
                break;
              }
            }
          }
  
          if (AttrLoc.isValid()) {
            // The ownership attributes are almost always written via
            // the predefined
            // __strong/__weak/__autoreleasing/__unsafe_unretained.
            if (AttrLoc.isMacroID())
              AttrLoc = S.SourceMgr.getImmediateExpansionRange(AttrLoc).first;
  
            S.Diag(AttrLoc, diag::warn_arc_lifetime_result_type)
              << T.getQualifiers().getObjCLifetime();
          }
        }
  
        if (LangOpts.CPlusPlus && D.getDeclSpec().hasTagDefinition()) {
          // C++ [dcl.fct]p6:
          //   Types shall not be defined in return or parameter types.
          TagDecl *Tag = cast<TagDecl>(D.getDeclSpec().getRepAsDecl());
          S.Diag(Tag->getLocation(), diag::err_type_defined_in_result_type)
            << Context.getTypeDeclType(Tag);
        }
  
        // Exception specs are not allowed in typedefs. Complain, but add it
        // anyway.
        if (IsTypedefName && FTI.getExceptionSpecType())
          S.Diag(FTI.getExceptionSpecLoc(), diag::err_exception_spec_in_typedef)
            << (D.getContext() == Declarator::AliasDeclContext ||
                D.getContext() == Declarator::AliasTemplateContext);
  
        // If we see "T var();" or "T var(T());" at block scope, it is probably
        // an attempt to initialize a variable, not a function declaration.
        if (FTI.isAmbiguous)
          warnAboutAmbiguousFunction(S, D, DeclType, T);
  
        FunctionType::ExtInfo EI(getCCForDeclaratorChunk(S, D, FTI, chunkIndex));
  
        if (!FTI.NumParams && !FTI.isVariadic && !LangOpts.CPlusPlus) {
          // Simple void foo(), where the incoming T is the result type.
          T = Context.getFunctionNoProtoType(T, EI);
        } else {
          // We allow a zero-parameter variadic function in C if the
          // function is marked with the "overloadable" attribute. Scan
          // for this attribute now.
          if (!FTI.NumParams && FTI.isVariadic && !LangOpts.CPlusPlus) {
            bool Overloadable = false;
            for (const AttributeList *Attrs = D.getAttributes();
                 Attrs; Attrs = Attrs->getNext()) {
              if (Attrs->getKind() == AttributeList::AT_Overloadable) {
                Overloadable = true;
                break;
              }
            }
  
            if (!Overloadable)
              S.Diag(FTI.getEllipsisLoc(), diag::err_ellipsis_first_param);
          }
  
          if (FTI.NumParams && FTI.Params[0].Param == nullptr) {
            // C99 6.7.5.3p3: Reject int(x,y,z) when it's not a function
            // definition.
            S.Diag(FTI.Params[0].IdentLoc,
                   diag::err_ident_list_in_fn_declaration);
            D.setInvalidType(true);
            // Recover by creating a K&R-style function type.
            T = Context.getFunctionNoProtoType(T, EI);
            break;
          }
  
          FunctionProtoType::ExtProtoInfo EPI;
          EPI.ExtInfo = EI;
          EPI.Variadic = FTI.isVariadic;
          EPI.HasTrailingReturn = FTI.hasTrailingReturnType();
          EPI.TypeQuals = FTI.TypeQuals;
          EPI.RefQualifier = !FTI.hasRefQualifier()? RQ_None
                      : FTI.RefQualifierIsLValueRef? RQ_LValue
                      : RQ_RValue;
  
          // Otherwise, we have a function with a parameter list that is
          // potentially variadic.
          SmallVector<QualType, 16> ParamTys;
          ParamTys.reserve(FTI.NumParams);
  
          SmallVector<bool, 16> ConsumedParameters;
          ConsumedParameters.reserve(FTI.NumParams);
          bool HasAnyConsumedParameters = false;
  
          for (unsigned i = 0, e = FTI.NumParams; i != e; ++i) {
            ParmVarDecl *Param = cast<ParmVarDecl>(FTI.Params[i].Param);
            QualType ParamTy = Param->getType();
            assert(!ParamTy.isNull() && "Couldn't parse type?");
  
            // Look for 'void'.  void is allowed only as a single parameter to a
            // function with no other parameters (C99 6.7.5.3p10).  We record
            // int(void) as a FunctionProtoType with an empty parameter list.
            if (ParamTy->isVoidType()) {
              // If this is something like 'float(int, void)', reject it.  'void'
              // is an incomplete type (C99 6.2.5p19) and function decls cannot
              // have parameters of incomplete type.
              if (FTI.NumParams != 1 || FTI.isVariadic) {
                S.Diag(DeclType.Loc, diag::err_void_only_param);
                ParamTy = Context.IntTy;
                Param->setType(ParamTy);
              } else if (FTI.Params[i].Ident) {
                // Reject, but continue to parse 'int(void abc)'.
                S.Diag(FTI.Params[i].IdentLoc, diag::err_param_with_void_type);
                ParamTy = Context.IntTy;
                Param->setType(ParamTy);
              } else {
                // Reject, but continue to parse 'float(const void)'.
                if (ParamTy.hasQualifiers())
                  S.Diag(DeclType.Loc, diag::err_void_param_qualified);
  
                // Do not add 'void' to the list.
                break;
              }
            } else if (ParamTy->isHalfType()) {
              // Disallow half FP parameters.
              // FIXME: This really should be in BuildFunctionType.
              if (S.getLangOpts().OpenCL) {
                if (!S.getOpenCLOptions().cl_khr_fp16) {
                  S.Diag(Param->getLocation(),
                    diag::err_opencl_half_param) << ParamTy;
                  D.setInvalidType();
                  Param->setInvalidDecl();
                }
              } else {
                S.Diag(Param->getLocation(),
                  diag::err_parameters_retval_cannot_have_fp16_type) << 0;
                D.setInvalidType();
              }
            } else if (!FTI.hasPrototype) {
              if (ParamTy->isPromotableIntegerType()) {
                ParamTy = Context.getPromotedIntegerType(ParamTy);
                Param->setKNRPromoted(true);
              } else if (const BuiltinType* BTy = ParamTy->getAs<BuiltinType>()) {
                if (BTy->getKind() == BuiltinType::Float) {
                  ParamTy = Context.DoubleTy;
                  Param->setKNRPromoted(true);
                }
              }
            }
  
            if (LangOpts.ObjCAutoRefCount) {
              bool Consumed = Param->hasAttr<NSConsumedAttr>();
              ConsumedParameters.push_back(Consumed);
              HasAnyConsumedParameters |= Consumed;
            }
  
            ParamTys.push_back(ParamTy);
          }
  
          if (HasAnyConsumedParameters)
            EPI.ConsumedParameters = ConsumedParameters.data();
  
          SmallVector<QualType, 4> Exceptions;
          SmallVector<ParsedType, 2> DynamicExceptions;
          SmallVector<SourceRange, 2> DynamicExceptionRanges;
          Expr *NoexceptExpr = nullptr;
  
          if (FTI.getExceptionSpecType() == EST_Dynamic) {
            // FIXME: It's rather inefficient to have to split into two vectors
            // here.
            unsigned N = FTI.NumExceptions;
            DynamicExceptions.reserve(N);
            DynamicExceptionRanges.reserve(N);
            for (unsigned I = 0; I != N; ++I) {
              DynamicExceptions.push_back(FTI.Exceptions[I].Ty);
              DynamicExceptionRanges.push_back(FTI.Exceptions[I].Range);
            }
          } else if (FTI.getExceptionSpecType() == EST_ComputedNoexcept) {
            NoexceptExpr = FTI.NoexceptExpr;
          }
  
          S.checkExceptionSpecification(FTI.getExceptionSpecType(),
                                        DynamicExceptions,
                                        DynamicExceptionRanges,
                                        NoexceptExpr,
                                        Exceptions,
                                        EPI);
  
          T = Context.getFunctionType(T, ParamTys, EPI);
        }
  
        break;
      }
      case DeclaratorChunk::MemberPointer:
        // The scope spec must refer to a class, or be dependent.
        CXXScopeSpec &SS = DeclType.Mem.Scope();
        QualType ClsType;
        if (SS.isInvalid()) {
          // Avoid emitting extra errors if we already errored on the scope.
          D.setInvalidType(true);
        } else if (S.isDependentScopeSpecifier(SS) ||
                   dyn_cast_or_null<CXXRecordDecl>(S.computeDeclContext(SS))) {
          NestedNameSpecifier *NNS = SS.getScopeRep();
          NestedNameSpecifier *NNSPrefix = NNS->getPrefix();
          switch (NNS->getKind()) {
          case NestedNameSpecifier::Identifier:
            ClsType = Context.getDependentNameType(ETK_None, NNSPrefix,
                                                   NNS->getAsIdentifier());
            break;
  
          case NestedNameSpecifier::Namespace:
          case NestedNameSpecifier::NamespaceAlias:
          case NestedNameSpecifier::Global:
            llvm_unreachable("Nested-name-specifier must name a type");
  
          case NestedNameSpecifier::TypeSpec:
          case NestedNameSpecifier::TypeSpecWithTemplate:
            ClsType = QualType(NNS->getAsType(), 0);
            // Note: if the NNS has a prefix and ClsType is a nondependent
            // TemplateSpecializationType, then the NNS prefix is NOT included
            // in ClsType; hence we wrap ClsType into an ElaboratedType.
            // NOTE: in particular, no wrap occurs if ClsType already is an
            // Elaborated, DependentName, or DependentTemplateSpecialization.
            if (NNSPrefix && isa<TemplateSpecializationType>(NNS->getAsType()))
              ClsType = Context.getElaboratedType(ETK_None, NNSPrefix, ClsType);
            break;
          }
        } else {
          S.Diag(DeclType.Mem.Scope().getBeginLoc(),
               diag::err_illegal_decl_mempointer_in_nonclass)
            << (D.getIdentifier() ? D.getIdentifier()->getName() : "type name")
            << DeclType.Mem.Scope().getRange();
          D.setInvalidType(true);
        }
  
        if (!ClsType.isNull())
          T = S.BuildMemberPointerType(T, ClsType, DeclType.Loc, D.getIdentifier());
        if (T.isNull()) {
          T = Context.IntTy;
          D.setInvalidType(true);
        } else if (DeclType.Mem.TypeQuals) {
          T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Mem.TypeQuals);
        }
        break;
      }
  
      if (T.isNull()) {
        D.setInvalidType(true);
        T = Context.IntTy;
      }
  
      // See if there are any attributes on this declarator chunk.
      if (AttributeList *attrs = const_cast<AttributeList*>(DeclType.getAttrs()))
        processTypeAttrs(state, T, TAL_DeclChunk, attrs);
    }
  
    if (LangOpts.CPlusPlus && T->isFunctionType()) {
      const FunctionProtoType *FnTy = T->getAs<FunctionProtoType>();
      assert(FnTy && "Why oh why is there not a FunctionProtoType here?");
  
      // C++ 8.3.5p4:
      //   A cv-qualifier-seq shall only be part of the function type
      //   for a nonstatic member function, the function type to which a pointer
      //   to member refers, or the top-level function type of a function typedef
      //   declaration.
      //
      // Core issue 547 also allows cv-qualifiers on function types that are
      // top-level template type arguments.
      bool FreeFunction;
      if (!D.getCXXScopeSpec().isSet()) {
        FreeFunction = ((D.getContext() != Declarator::MemberContext &&
                         D.getContext() != Declarator::LambdaExprContext) ||
                        D.getDeclSpec().isFriendSpecified());
      } else {
        DeclContext *DC = S.computeDeclContext(D.getCXXScopeSpec());
        FreeFunction = (DC && !DC->isRecord());
      }
  
      // C++11 [dcl.fct]p6 (w/DR1417):
      // An attempt to specify a function type with a cv-qualifier-seq or a
      // ref-qualifier (including by typedef-name) is ill-formed unless it is:
      //  - the function type for a non-static member function,
      //  - the function type to which a pointer to member refers,
      //  - the top-level function type of a function typedef declaration or
      //    alias-declaration,
      //  - the type-id in the default argument of a type-parameter, or
      //  - the type-id of a template-argument for a type-parameter
      //
      // FIXME: Checking this here is insufficient. We accept-invalid on:
      //
      //   template<typename T> struct S { void f(T); };
      //   S<int() const> s;
      //
      // ... for instance.
      if (IsQualifiedFunction &&
          !(!FreeFunction &&
            D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_static) &&
          !IsTypedefName &&
          D.getContext() != Declarator::TemplateTypeArgContext) {
        SourceLocation Loc = D.getLocStart();
        SourceRange RemovalRange;
        unsigned I;
        if (D.isFunctionDeclarator(I)) {
          SmallVector<SourceLocation, 4> RemovalLocs;
          const DeclaratorChunk &Chunk = D.getTypeObject(I);
          assert(Chunk.Kind == DeclaratorChunk::Function);
          if (Chunk.Fun.hasRefQualifier())
            RemovalLocs.push_back(Chunk.Fun.getRefQualifierLoc());
          if (Chunk.Fun.TypeQuals & Qualifiers::Const)
            RemovalLocs.push_back(Chunk.Fun.getConstQualifierLoc());
          if (Chunk.Fun.TypeQuals & Qualifiers::Volatile)
            RemovalLocs.push_back(Chunk.Fun.getVolatileQualifierLoc());
          // FIXME: We do not track the location of the __restrict qualifier.
          //if (Chunk.Fun.TypeQuals & Qualifiers::Restrict)
          //  RemovalLocs.push_back(Chunk.Fun.getRestrictQualifierLoc());
          if (!RemovalLocs.empty()) {
            std::sort(RemovalLocs.begin(), RemovalLocs.end(),
                      BeforeThanCompare<SourceLocation>(S.getSourceManager()));
            RemovalRange = SourceRange(RemovalLocs.front(), RemovalLocs.back());
            Loc = RemovalLocs.front();
          }
        }
  
        S.Diag(Loc, diag::err_invalid_qualified_function_type)
          << FreeFunction << D.isFunctionDeclarator() << T
          << getFunctionQualifiersAsString(FnTy)
          << FixItHint::CreateRemoval(RemovalRange);
  
        // Strip the cv-qualifiers and ref-qualifiers from the type.
        FunctionProtoType::ExtProtoInfo EPI = FnTy->getExtProtoInfo();
        EPI.TypeQuals = 0;
        EPI.RefQualifier = RQ_None;
  
        T = Context.getFunctionType(FnTy->getReturnType(), FnTy->getParamTypes(),
                                    EPI);
        // Rebuild any parens around the identifier in the function type.
        for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
          if (D.getTypeObject(i).Kind != DeclaratorChunk::Paren)
            break;
          T = S.BuildParenType(T);
        }
      }
    }
  
    // Apply any undistributed attributes from the declarator.
    if (!T.isNull())
      if (AttributeList *attrs = D.getAttributes())
        processTypeAttrs(state, T, TAL_DeclName, attrs);
  
    // Diagnose any ignored type attributes.
    if (!T.isNull()) state.diagnoseIgnoredTypeAttrs(T);
  
    // C++0x [dcl.constexpr]p9:
    //  A constexpr specifier used in an object declaration declares the object
    //  as const.
    if (D.getDeclSpec().isConstexprSpecified() && T->isObjectType()) {
      T.addConst();
    }
  
    // If there was an ellipsis in the declarator, the declaration declares a
    // parameter pack whose type may be a pack expansion type.
    if (D.hasEllipsis() && !T.isNull()) {
      // C++0x [dcl.fct]p13:
      //   A declarator-id or abstract-declarator containing an ellipsis shall
      //   only be used in a parameter-declaration. Such a parameter-declaration
      //   is a parameter pack (14.5.3). [...]
      switch (D.getContext()) {
      case Declarator::PrototypeContext:
      case Declarator::LambdaExprParameterContext:
        // C++0x [dcl.fct]p13:
        //   [...] When it is part of a parameter-declaration-clause, the
        //   parameter pack is a function parameter pack (14.5.3). The type T
        //   of the declarator-id of the function parameter pack shall contain
        //   a template parameter pack; each template parameter pack in T is
        //   expanded by the function parameter pack.
        //
        // We represent function parameter packs as function parameters whose
        // type is a pack expansion.
        if (!T->containsUnexpandedParameterPack()) {
          S.Diag(D.getEllipsisLoc(),
               diag::err_function_parameter_pack_without_parameter_packs)
            << T <<  D.getSourceRange();
          D.setEllipsisLoc(SourceLocation());
        } else {
          T = Context.getPackExpansionType(T, None);
        }
        break;
      case Declarator::TemplateParamContext:
        // C++0x [temp.param]p15:
        //   If a template-parameter is a [...] is a parameter-declaration that
        //   declares a parameter pack (8.3.5), then the template-parameter is a
        //   template parameter pack (14.5.3).
        //
        // Note: core issue 778 clarifies that, if there are any unexpanded
        // parameter packs in the type of the non-type template parameter, then
        // it expands those parameter packs.
        if (T->containsUnexpandedParameterPack())
          T = Context.getPackExpansionType(T, None);
        else
          S.Diag(D.getEllipsisLoc(),
                 LangOpts.CPlusPlus11
                   ? diag::warn_cxx98_compat_variadic_templates
                   : diag::ext_variadic_templates);
        break;
  
      case Declarator::FileContext:
      case Declarator::KNRTypeListContext:
      case Declarator::ObjCParameterContext:  // FIXME: special diagnostic here?
      case Declarator::ObjCResultContext:     // FIXME: special diagnostic here?
      case Declarator::TypeNameContext:
      case Declarator::CXXNewContext:
      case Declarator::AliasDeclContext:
      case Declarator::AliasTemplateContext:
      case Declarator::MemberContext:
      case Declarator::BlockContext:
      case Declarator::ForContext:
      case Declarator::ConditionContext:
      case Declarator::CXXCatchContext:
      case Declarator::ObjCCatchContext:
      case Declarator::BlockLiteralContext:
      case Declarator::LambdaExprContext:
      case Declarator::ConversionIdContext:
      case Declarator::TrailingReturnContext:
      case Declarator::TemplateTypeArgContext:
        // FIXME: We may want to allow parameter packs in block-literal contexts
        // in the future.
        S.Diag(D.getEllipsisLoc(), diag::err_ellipsis_in_declarator_not_parameter);
        D.setEllipsisLoc(SourceLocation());
        break;
      }
    }
  
    if (T.isNull())
      return Context.getNullTypeSourceInfo();
    else if (D.isInvalidType())
      return Context.getTrivialTypeSourceInfo(T);
  
    return S.GetTypeSourceInfoForDeclarator(D, T, TInfo);
  }
  
  /// GetTypeForDeclarator - Convert the type for the specified
  /// declarator to Type instances.
  ///
  /// The result of this call will never be null, but the associated
  /// type may be a null type if there's an unrecoverable error.
  TypeSourceInfo *Sema::GetTypeForDeclarator(Declarator &D, Scope *S) {
    // Determine the type of the declarator. Not all forms of declarator
    // have a type.
  
    TypeProcessingState state(*this, D);
  
    TypeSourceInfo *ReturnTypeInfo = nullptr;
    QualType T = GetDeclSpecTypeForDeclarator(state, ReturnTypeInfo);
    if (T.isNull())
      return Context.getNullTypeSourceInfo();
  
    if (D.isPrototypeContext() && getLangOpts().ObjCAutoRefCount)
      inferARCWriteback(state, T);
  
    return GetFullTypeForDeclarator(state, T, ReturnTypeInfo);
  }
  
  static void transferARCOwnershipToDeclSpec(Sema &S,
                                             QualType &declSpecTy,
                                             Qualifiers::ObjCLifetime ownership) {
    if (declSpecTy->isObjCRetainableType() &&
        declSpecTy.getObjCLifetime() == Qualifiers::OCL_None) {
      Qualifiers qs;
      qs.addObjCLifetime(ownership);
      declSpecTy = S.Context.getQualifiedType(declSpecTy, qs);
    }
  }
  
  static void transferARCOwnershipToDeclaratorChunk(TypeProcessingState &state,
                                              Qualifiers::ObjCLifetime ownership,
                                              unsigned chunkIndex) {
    Sema &S = state.getSema();
    Declarator &D = state.getDeclarator();
  
    // Look for an explicit lifetime attribute.
    DeclaratorChunk &chunk = D.getTypeObject(chunkIndex);
    for (const AttributeList *attr = chunk.getAttrs(); attr;
           attr = attr->getNext())
      if (attr->getKind() == AttributeList::AT_ObjCOwnership)
        return;
  
    const char *attrStr = nullptr;
    switch (ownership) {
    case Qualifiers::OCL_None: llvm_unreachable("no ownership!");
    case Qualifiers::OCL_ExplicitNone: attrStr = "none"; break;
    case Qualifiers::OCL_Strong: attrStr = "strong"; break;
    case Qualifiers::OCL_Weak: attrStr = "weak"; break;
    case Qualifiers::OCL_Autoreleasing: attrStr = "autoreleasing"; break;
    }
  
    IdentifierLoc *Arg = new (S.Context) IdentifierLoc;
    Arg->Ident = &S.Context.Idents.get(attrStr);
    Arg->Loc = SourceLocation();
  
    ArgsUnion Args(Arg);
  
    // If there wasn't one, add one (with an invalid source location
    // so that we don't make an AttributedType for it).
    AttributeList *attr = D.getAttributePool()
      .create(&S.Context.Idents.get("objc_ownership"), SourceLocation(),
              /*scope*/ nullptr, SourceLocation(),
              /*args*/ &Args, 1, AttributeList::AS_GNU);
    spliceAttrIntoList(*attr, chunk.getAttrListRef());
  
    // TODO: mark whether we did this inference?
  }
  
  /// \brief Used for transferring ownership in casts resulting in l-values.
  static void transferARCOwnership(TypeProcessingState &state,
                                   QualType &declSpecTy,
                                   Qualifiers::ObjCLifetime ownership) {
    Sema &S = state.getSema();
    Declarator &D = state.getDeclarator();
  
    int inner = -1;
    bool hasIndirection = false;
    for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
      DeclaratorChunk &chunk = D.getTypeObject(i);
      switch (chunk.Kind) {
      case DeclaratorChunk::Paren:
        // Ignore parens.
        break;
  
      case DeclaratorChunk::Array:
      case DeclaratorChunk::Reference:
      case DeclaratorChunk::Pointer:
        if (inner != -1)
          hasIndirection = true;
        inner = i;
        break;
  
      case DeclaratorChunk::BlockPointer:
        if (inner != -1)
          transferARCOwnershipToDeclaratorChunk(state, ownership, i);
        return;
  
      case DeclaratorChunk::Function:
      case DeclaratorChunk::MemberPointer:
        return;
      }
    }
  
    if (inner == -1)
      return;
  
    DeclaratorChunk &chunk = D.getTypeObject(inner);
    if (chunk.Kind == DeclaratorChunk::Pointer) {
      if (declSpecTy->isObjCRetainableType())
        return transferARCOwnershipToDeclSpec(S, declSpecTy, ownership);
      if (declSpecTy->isObjCObjectType() && hasIndirection)
        return transferARCOwnershipToDeclaratorChunk(state, ownership, inner);
    } else {
      assert(chunk.Kind == DeclaratorChunk::Array ||
             chunk.Kind == DeclaratorChunk::Reference);
      return transferARCOwnershipToDeclSpec(S, declSpecTy, ownership);
    }
  }
  
  TypeSourceInfo *Sema::GetTypeForDeclaratorCast(Declarator &D, QualType FromTy) {
    TypeProcessingState state(*this, D);
  
    TypeSourceInfo *ReturnTypeInfo = nullptr;
    QualType declSpecTy = GetDeclSpecTypeForDeclarator(state, ReturnTypeInfo);
    if (declSpecTy.isNull())
      return Context.getNullTypeSourceInfo();
  
    if (getLangOpts().ObjCAutoRefCount) {
      Qualifiers::ObjCLifetime ownership = Context.getInnerObjCOwnership(FromTy);
      if (ownership != Qualifiers::OCL_None)
        transferARCOwnership(state, declSpecTy, ownership);
    }
  
    return GetFullTypeForDeclarator(state, declSpecTy, ReturnTypeInfo);
  }
  
  /// Map an AttributedType::Kind to an AttributeList::Kind.
  static AttributeList::Kind getAttrListKind(AttributedType::Kind kind) {
    switch (kind) {
    case AttributedType::attr_address_space:
      return AttributeList::AT_AddressSpace;
    case AttributedType::attr_regparm:
      return AttributeList::AT_Regparm;
    case AttributedType::attr_vector_size:
      return AttributeList::AT_VectorSize;
    case AttributedType::attr_neon_vector_type:
      return AttributeList::AT_NeonVectorType;
    case AttributedType::attr_neon_polyvector_type:
      return AttributeList::AT_NeonPolyVectorType;
    case AttributedType::attr_objc_gc:
      return AttributeList::AT_ObjCGC;
    case AttributedType::attr_objc_ownership:
      return AttributeList::AT_ObjCOwnership;
    case AttributedType::attr_noreturn:
      return AttributeList::AT_NoReturn;
    case AttributedType::attr_cdecl:
      return AttributeList::AT_CDecl;
    case AttributedType::attr_fastcall:
      return AttributeList::AT_FastCall;
    case AttributedType::attr_stdcall:
      return AttributeList::AT_StdCall;
    case AttributedType::attr_thiscall:
      return AttributeList::AT_ThisCall;
    case AttributedType::attr_pascal:
      return AttributeList::AT_Pascal;
    case AttributedType::attr_pcs:
    case AttributedType::attr_pcs_vfp:
      return AttributeList::AT_Pcs;
    case AttributedType::attr_pnaclcall:
      return AttributeList::AT_PnaclCall;
    case AttributedType::attr_inteloclbicc:
      return AttributeList::AT_IntelOclBicc;
    case AttributedType::attr_ms_abi:
      return AttributeList::AT_MSABI;
    case AttributedType::attr_sysv_abi:
      return AttributeList::AT_SysVABI;
    case AttributedType::attr_ptr32:
      return AttributeList::AT_Ptr32;
    case AttributedType::attr_ptr64:
      return AttributeList::AT_Ptr64;
    case AttributedType::attr_sptr:
      return AttributeList::AT_SPtr;
    case AttributedType::attr_uptr:
      return AttributeList::AT_UPtr;
    }
    llvm_unreachable("unexpected attribute kind!");
  }
  
  static void fillAttributedTypeLoc(AttributedTypeLoc TL,
                                    const AttributeList *attrs) {
    AttributedType::Kind kind = TL.getAttrKind();
  
    assert(attrs && "no type attributes in the expected location!");
    AttributeList::Kind parsedKind = getAttrListKind(kind);
    while (attrs->getKind() != parsedKind) {
      attrs = attrs->getNext();
      assert(attrs && "no matching attribute in expected location!");
    }
  
    TL.setAttrNameLoc(attrs->getLoc());
    if (TL.hasAttrExprOperand()) {
      assert(attrs->isArgExpr(0) && "mismatched attribute operand kind");
      TL.setAttrExprOperand(attrs->getArgAsExpr(0));
    } else if (TL.hasAttrEnumOperand()) {
      assert((attrs->isArgIdent(0) || attrs->isArgExpr(0)) &&
             "unexpected attribute operand kind");
      if (attrs->isArgIdent(0))
        TL.setAttrEnumOperandLoc(attrs->getArgAsIdent(0)->Loc);
      else
        TL.setAttrEnumOperandLoc(attrs->getArgAsExpr(0)->getExprLoc());
    }
  
    // FIXME: preserve this information to here.
    if (TL.hasAttrOperand())
      TL.setAttrOperandParensRange(SourceRange());
  }
  
  namespace {
    class TypeSpecLocFiller : public TypeLocVisitor<TypeSpecLocFiller> {
      ASTContext &Context;
      const DeclSpec &DS;
  
    public:
      TypeSpecLocFiller(ASTContext &Context, const DeclSpec &DS)
        : Context(Context), DS(DS) {}
  
      void VisitAttributedTypeLoc(AttributedTypeLoc TL) {
        fillAttributedTypeLoc(TL, DS.getAttributes().getList());
        Visit(TL.getModifiedLoc());
      }
      void VisitQualifiedTypeLoc(QualifiedTypeLoc TL) {
        Visit(TL.getUnqualifiedLoc());
      }
      void VisitTypedefTypeLoc(TypedefTypeLoc TL) {
        TL.setNameLoc(DS.getTypeSpecTypeLoc());
      }
      void VisitObjCInterfaceTypeLoc(ObjCInterfaceTypeLoc TL) {
        TL.setNameLoc(DS.getTypeSpecTypeLoc());
        // FIXME. We should have DS.getTypeSpecTypeEndLoc(). But, it requires
        // addition field. What we have is good enough for dispay of location
        // of 'fixit' on interface name.
        TL.setNameEndLoc(DS.getLocEnd());
      }
      void VisitObjCObjectTypeLoc(ObjCObjectTypeLoc TL) {
        // Handle the base type, which might not have been written explicitly.
        if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
          TL.setHasBaseTypeAsWritten(false);
          TL.getBaseLoc().initialize(Context, SourceLocation());
        } else {
          TL.setHasBaseTypeAsWritten(true);
          Visit(TL.getBaseLoc());
        }
  
        // Protocol qualifiers.
        if (DS.getProtocolQualifiers()) {
          assert(TL.getNumProtocols() > 0);
          assert(TL.getNumProtocols() == DS.getNumProtocolQualifiers());
          TL.setLAngleLoc(DS.getProtocolLAngleLoc());
          TL.setRAngleLoc(DS.getSourceRange().getEnd());
          for (unsigned i = 0, e = DS.getNumProtocolQualifiers(); i != e; ++i)
            TL.setProtocolLoc(i, DS.getProtocolLocs()[i]);
        } else {
          assert(TL.getNumProtocols() == 0);
          TL.setLAngleLoc(SourceLocation());
          TL.setRAngleLoc(SourceLocation());
        }
      }
      void VisitObjCObjectPointerTypeLoc(ObjCObjectPointerTypeLoc TL) {
        TL.setStarLoc(SourceLocation());
        Visit(TL.getPointeeLoc());
      }
      void VisitTemplateSpecializationTypeLoc(TemplateSpecializationTypeLoc TL) {
        TypeSourceInfo *TInfo = nullptr;
        Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
  
        // If we got no declarator info from previous Sema routines,
        // just fill with the typespec loc.
        if (!TInfo) {
          TL.initialize(Context, DS.getTypeSpecTypeNameLoc());
          return;
        }
  
        TypeLoc OldTL = TInfo->getTypeLoc();
        if (TInfo->getType()->getAs<ElaboratedType>()) {
          ElaboratedTypeLoc ElabTL = OldTL.castAs<ElaboratedTypeLoc>();
          TemplateSpecializationTypeLoc NamedTL = ElabTL.getNamedTypeLoc()
              .castAs<TemplateSpecializationTypeLoc>();
          TL.copy(NamedTL);
        } else {
          TL.copy(OldTL.castAs<TemplateSpecializationTypeLoc>());
          assert(TL.getRAngleLoc() == OldTL.castAs<TemplateSpecializationTypeLoc>().getRAngleLoc());
        }
          
      }
      void VisitTypeOfExprTypeLoc(TypeOfExprTypeLoc TL) {
        assert(DS.getTypeSpecType() == DeclSpec::TST_typeofExpr);
        TL.setTypeofLoc(DS.getTypeSpecTypeLoc());
        TL.setParensRange(DS.getTypeofParensRange());
      }
      void VisitTypeOfTypeLoc(TypeOfTypeLoc TL) {
        assert(DS.getTypeSpecType() == DeclSpec::TST_typeofType);
        TL.setTypeofLoc(DS.getTypeSpecTypeLoc());
        TL.setParensRange(DS.getTypeofParensRange());
        assert(DS.getRepAsType());
        TypeSourceInfo *TInfo = nullptr;
        Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
        TL.setUnderlyingTInfo(TInfo);
      }
      void VisitUnaryTransformTypeLoc(UnaryTransformTypeLoc TL) {
        // FIXME: This holds only because we only have one unary transform.
        assert(DS.getTypeSpecType() == DeclSpec::TST_underlyingType);
        TL.setKWLoc(DS.getTypeSpecTypeLoc());
        TL.setParensRange(DS.getTypeofParensRange());
        assert(DS.getRepAsType());
        TypeSourceInfo *TInfo = nullptr;
        Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
        TL.setUnderlyingTInfo(TInfo);
      }
      void VisitBuiltinTypeLoc(BuiltinTypeLoc TL) {
        // By default, use the source location of the type specifier.
        TL.setBuiltinLoc(DS.getTypeSpecTypeLoc());
        if (TL.needsExtraLocalData()) {
          // Set info for the written builtin specifiers.
          TL.getWrittenBuiltinSpecs() = DS.getWrittenBuiltinSpecs();
          // Try to have a meaningful source location.
          if (TL.getWrittenSignSpec() != TSS_unspecified)
            // Sign spec loc overrides the others (e.g., 'unsigned long').
            TL.setBuiltinLoc(DS.getTypeSpecSignLoc());
          else if (TL.getWrittenWidthSpec() != TSW_unspecified)
            // Width spec loc overrides type spec loc (e.g., 'short int').
            TL.setBuiltinLoc(DS.getTypeSpecWidthLoc());
        }
      }
      void VisitElaboratedTypeLoc(ElaboratedTypeLoc TL) {
        ElaboratedTypeKeyword Keyword
          = TypeWithKeyword::getKeywordForTypeSpec(DS.getTypeSpecType());
        if (DS.getTypeSpecType() == TST_typename) {
          TypeSourceInfo *TInfo = nullptr;
          Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
          if (TInfo) {
            TL.copy(TInfo->getTypeLoc().castAs<ElaboratedTypeLoc>());
            return;
          }
        }
        TL.setElaboratedKeywordLoc(Keyword != ETK_None
                                   ? DS.getTypeSpecTypeLoc()
                                   : SourceLocation());
        const CXXScopeSpec& SS = DS.getTypeSpecScope();
        TL.setQualifierLoc(SS.getWithLocInContext(Context));
        Visit(TL.getNextTypeLoc().getUnqualifiedLoc());
      }
      void VisitDependentNameTypeLoc(DependentNameTypeLoc TL) {
        assert(DS.getTypeSpecType() == TST_typename);
        TypeSourceInfo *TInfo = nullptr;
        Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
        assert(TInfo);
        TL.copy(TInfo->getTypeLoc().castAs<DependentNameTypeLoc>());
      }
      void VisitDependentTemplateSpecializationTypeLoc(
                                   DependentTemplateSpecializationTypeLoc TL) {
        assert(DS.getTypeSpecType() == TST_typename);
        TypeSourceInfo *TInfo = nullptr;
        Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
        assert(TInfo);
        TL.copy(
            TInfo->getTypeLoc().castAs<DependentTemplateSpecializationTypeLoc>());
      }
      void VisitTagTypeLoc(TagTypeLoc TL) {
        TL.setNameLoc(DS.getTypeSpecTypeNameLoc());
      }
      void VisitAtomicTypeLoc(AtomicTypeLoc TL) {
        // An AtomicTypeLoc can come from either an _Atomic(...) type specifier
        // or an _Atomic qualifier.
        if (DS.getTypeSpecType() == DeclSpec::TST_atomic) {
          TL.setKWLoc(DS.getTypeSpecTypeLoc());
          TL.setParensRange(DS.getTypeofParensRange());
  
          TypeSourceInfo *TInfo = nullptr;
          Sema::GetTypeFromParser(DS.getRepAsType(), &TInfo);
          assert(TInfo);
          TL.getValueLoc().initializeFullCopy(TInfo->getTypeLoc());
        } else {
          TL.setKWLoc(DS.getAtomicSpecLoc());
          // No parens, to indicate this was spelled as an _Atomic qualifier.
          TL.setParensRange(SourceRange());
          Visit(TL.getValueLoc());
        }
      }
  
      void VisitTypeLoc(TypeLoc TL) {
        // FIXME: add other typespec types and change this to an assert.
        TL.initialize(Context, DS.getTypeSpecTypeLoc());
      }
    };
  
    class DeclaratorLocFiller : public TypeLocVisitor<DeclaratorLocFiller> {
      ASTContext &Context;
      const DeclaratorChunk &Chunk;
  
    public:
      DeclaratorLocFiller(ASTContext &Context, const DeclaratorChunk &Chunk)
        : Context(Context), Chunk(Chunk) {}
  
      void VisitQualifiedTypeLoc(QualifiedTypeLoc TL) {
        llvm_unreachable("qualified type locs not expected here!");
      }
      void VisitDecayedTypeLoc(DecayedTypeLoc TL) {
        llvm_unreachable("decayed type locs not expected here!");
      }
  
      void VisitAttributedTypeLoc(AttributedTypeLoc TL) {
        fillAttributedTypeLoc(TL, Chunk.getAttrs());
      }
      void VisitAdjustedTypeLoc(AdjustedTypeLoc TL) {
        // nothing
      }
      void VisitBlockPointerTypeLoc(BlockPointerTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::BlockPointer);
        TL.setCaretLoc(Chunk.Loc);
      }
      void VisitPointerTypeLoc(PointerTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Pointer);
        TL.setStarLoc(Chunk.Loc);
      }
      void VisitObjCObjectPointerTypeLoc(ObjCObjectPointerTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Pointer);
        TL.setStarLoc(Chunk.Loc);
      }
      void VisitMemberPointerTypeLoc(MemberPointerTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::MemberPointer);
        const CXXScopeSpec& SS = Chunk.Mem.Scope();
        NestedNameSpecifierLoc NNSLoc = SS.getWithLocInContext(Context);
  
        const Type* ClsTy = TL.getClass();
        QualType ClsQT = QualType(ClsTy, 0);
        TypeSourceInfo *ClsTInfo = Context.CreateTypeSourceInfo(ClsQT, 0);
        // Now copy source location info into the type loc component.
        TypeLoc ClsTL = ClsTInfo->getTypeLoc();
        switch (NNSLoc.getNestedNameSpecifier()->getKind()) {
        case NestedNameSpecifier::Identifier:
          assert(isa<DependentNameType>(ClsTy) && "Unexpected TypeLoc");
          {
            DependentNameTypeLoc DNTLoc = ClsTL.castAs<DependentNameTypeLoc>();
            DNTLoc.setElaboratedKeywordLoc(SourceLocation());
            DNTLoc.setQualifierLoc(NNSLoc.getPrefix());
            DNTLoc.setNameLoc(NNSLoc.getLocalBeginLoc());
          }
          break;
  
        case NestedNameSpecifier::TypeSpec:
        case NestedNameSpecifier::TypeSpecWithTemplate:
          if (isa<ElaboratedType>(ClsTy)) {
            ElaboratedTypeLoc ETLoc = ClsTL.castAs<ElaboratedTypeLoc>();
            ETLoc.setElaboratedKeywordLoc(SourceLocation());
            ETLoc.setQualifierLoc(NNSLoc.getPrefix());
            TypeLoc NamedTL = ETLoc.getNamedTypeLoc();
            NamedTL.initializeFullCopy(NNSLoc.getTypeLoc());
          } else {
            ClsTL.initializeFullCopy(NNSLoc.getTypeLoc());
          }
          break;
  
        case NestedNameSpecifier::Namespace:
        case NestedNameSpecifier::NamespaceAlias:
        case NestedNameSpecifier::Global:
          llvm_unreachable("Nested-name-specifier must name a type");
        }
  
        // Finally fill in MemberPointerLocInfo fields.
        TL.setStarLoc(Chunk.Loc);
        TL.setClassTInfo(ClsTInfo);
      }
      void VisitLValueReferenceTypeLoc(LValueReferenceTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Reference);
        // 'Amp' is misleading: this might have been originally
        /// spelled with AmpAmp.
        TL.setAmpLoc(Chunk.Loc);
      }
      void VisitRValueReferenceTypeLoc(RValueReferenceTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Reference);
        assert(!Chunk.Ref.LValueRef);
        TL.setAmpAmpLoc(Chunk.Loc);
      }
      void VisitArrayTypeLoc(ArrayTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Array);
        TL.setLBracketLoc(Chunk.Loc);
        TL.setRBracketLoc(Chunk.EndLoc);
        TL.setSizeExpr(static_cast<Expr*>(Chunk.Arr.NumElts));
      }
      void VisitFunctionTypeLoc(FunctionTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Function);
        TL.setLocalRangeBegin(Chunk.Loc);
        TL.setLocalRangeEnd(Chunk.EndLoc);
  
        const DeclaratorChunk::FunctionTypeInfo &FTI = Chunk.Fun;
        TL.setLParenLoc(FTI.getLParenLoc());
        TL.setRParenLoc(FTI.getRParenLoc());
        for (unsigned i = 0, e = TL.getNumParams(), tpi = 0; i != e; ++i) {
          ParmVarDecl *Param = cast<ParmVarDecl>(FTI.Params[i].Param);
          TL.setParam(tpi++, Param);
        }
        // FIXME: exception specs
      }
      void VisitParenTypeLoc(ParenTypeLoc TL) {
        assert(Chunk.Kind == DeclaratorChunk::Paren);
        TL.setLParenLoc(Chunk.Loc);
        TL.setRParenLoc(Chunk.EndLoc);
      }
  
      void VisitTypeLoc(TypeLoc TL) {
        llvm_unreachable("unsupported TypeLoc kind in declarator!");
      }
    };
  }
  
  static void fillAtomicQualLoc(AtomicTypeLoc ATL, const DeclaratorChunk &Chunk) {
    SourceLocation Loc;
    switch (Chunk.Kind) {
    case DeclaratorChunk::Function:
    case DeclaratorChunk::Array:
    case DeclaratorChunk::Paren:
      llvm_unreachable("cannot be _Atomic qualified");
  
    case DeclaratorChunk::Pointer:
      Loc = SourceLocation::getFromRawEncoding(Chunk.Ptr.AtomicQualLoc);
      break;
  
    case DeclaratorChunk::BlockPointer:
    case DeclaratorChunk::Reference:
    case DeclaratorChunk::MemberPointer:
      // FIXME: Provide a source location for the _Atomic keyword.
      break;
    }
  
    ATL.setKWLoc(Loc);
    ATL.setParensRange(SourceRange());
  }
  
  /// \brief Create and instantiate a TypeSourceInfo with type source information.
  ///
  /// \param T QualType referring to the type as written in source code.
  ///
  /// \param ReturnTypeInfo For declarators whose return type does not show
  /// up in the normal place in the declaration specifiers (such as a C++
  /// conversion function), this pointer will refer to a type source information
  /// for that return type.
  TypeSourceInfo *
  Sema::GetTypeSourceInfoForDeclarator(Declarator &D, QualType T,
                                       TypeSourceInfo *ReturnTypeInfo) {
    TypeSourceInfo *TInfo = Context.CreateTypeSourceInfo(T);
    UnqualTypeLoc CurrTL = TInfo->getTypeLoc().getUnqualifiedLoc();
  
    // Handle parameter packs whose type is a pack expansion.
    if (isa<PackExpansionType>(T)) {
      CurrTL.castAs<PackExpansionTypeLoc>().setEllipsisLoc(D.getEllipsisLoc());
      CurrTL = CurrTL.getNextTypeLoc().getUnqualifiedLoc();
    }
  
    for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
      // An AtomicTypeLoc might be produced by an atomic qualifier in this
      // declarator chunk.
      if (AtomicTypeLoc ATL = CurrTL.getAs<AtomicTypeLoc>()) {
        fillAtomicQualLoc(ATL, D.getTypeObject(i));
        CurrTL = ATL.getValueLoc().getUnqualifiedLoc();
      }
  
      while (AttributedTypeLoc TL = CurrTL.getAs<AttributedTypeLoc>()) {
        fillAttributedTypeLoc(TL, D.getTypeObject(i).getAttrs());
        CurrTL = TL.getNextTypeLoc().getUnqualifiedLoc();
      }
  
      // FIXME: Ordering here?
      while (AdjustedTypeLoc TL = CurrTL.getAs<AdjustedTypeLoc>())
        CurrTL = TL.getNextTypeLoc().getUnqualifiedLoc();
  
      DeclaratorLocFiller(Context, D.getTypeObject(i)).Visit(CurrTL);
      CurrTL = CurrTL.getNextTypeLoc().getUnqualifiedLoc();
    }
  
    // If we have different source information for the return type, use
    // that.  This really only applies to C++ conversion functions.
    if (ReturnTypeInfo) {
      TypeLoc TL = ReturnTypeInfo->getTypeLoc();
      assert(TL.getFullDataSize() == CurrTL.getFullDataSize());
      memcpy(CurrTL.getOpaqueData(), TL.getOpaqueData(), TL.getFullDataSize());
    } else {
      TypeSpecLocFiller(Context, D.getDeclSpec()).Visit(CurrTL);
    }
  
    return TInfo;
  }
  
  /// \brief Create a LocInfoType to hold the given QualType and TypeSourceInfo.
  ParsedType Sema::CreateParsedType(QualType T, TypeSourceInfo *TInfo) {
    // FIXME: LocInfoTypes are "transient", only needed for passing to/from Parser
    // and Sema during declaration parsing. Try deallocating/caching them when
    // it's appropriate, instead of allocating them and keeping them around.
    LocInfoType *LocT = (LocInfoType*)BumpAlloc.Allocate(sizeof(LocInfoType),
                                                         TypeAlignment);
    new (LocT) LocInfoType(T, TInfo);
    assert(LocT->getTypeClass() != T->getTypeClass() &&
           "LocInfoType's TypeClass conflicts with an existing Type class");
    return ParsedType::make(QualType(LocT, 0));
  }
  
  void LocInfoType::getAsStringInternal(std::string &Str,
                                        const PrintingPolicy &Policy) const {
    llvm_unreachable("LocInfoType leaked into the type system; an opaque TypeTy*"
           " was used directly instead of getting the QualType through"
           " GetTypeFromParser");
  }
  
  TypeResult Sema::ActOnTypeName(Scope *S, Declarator &D) {
    // C99 6.7.6: Type names have no identifier.  This is already validated by
    // the parser.
    assert(D.getIdentifier() == nullptr &&
           "Type name should have no identifier!");
  
    TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
    QualType T = TInfo->getType();
    if (D.isInvalidType())
      return true;
  
    // Make sure there are no unused decl attributes on the declarator.
    // We don't want to do this for ObjC parameters because we're going
    // to apply them to the actual parameter declaration.
    // Likewise, we don't want to do this for alias declarations, because
    // we are actually going to build a declaration from this eventually.
    if (D.getContext() != Declarator::ObjCParameterContext &&
        D.getContext() != Declarator::AliasDeclContext &&
        D.getContext() != Declarator::AliasTemplateContext)
      checkUnusedDeclAttributes(D);
  
    if (getLangOpts().CPlusPlus) {
      // Check that there are no default arguments (C++ only).
      CheckExtraCXXDefaultArguments(D);
    }
  
    return CreateParsedType(T, TInfo);
  }
  
  ParsedType Sema::ActOnObjCInstanceType(SourceLocation Loc) {
    QualType T = Context.getObjCInstanceType();
    TypeSourceInfo *TInfo = Context.getTrivialTypeSourceInfo(T, Loc);
    return CreateParsedType(T, TInfo);
  }
  
  
  //===----------------------------------------------------------------------===//
  // Type Attribute Processing
  //===----------------------------------------------------------------------===//
  
  /// HandleAddressSpaceTypeAttribute - Process an address_space attribute on the
  /// specified type.  The attribute contains 1 argument, the id of the address
  /// space for the type.
  static void HandleAddressSpaceTypeAttribute(QualType &Type,
                                              const AttributeList &Attr, Sema &S){
  
    // If this type is already address space qualified, reject it.
    // ISO/IEC TR 18037 S5.3 (amending C99 6.7.3): "No type shall be qualified by
    // qualifiers for two or more different address spaces."
    if (Type.getAddressSpace()) {
      S.Diag(Attr.getLoc(), diag::err_attribute_address_multiple_qualifiers);
      Attr.setInvalid();
      return;
    }
  
    // ISO/IEC TR 18037 S5.3 (amending C99 6.7.3): "A function type shall not be
    // qualified by an address-space qualifier."
    if (Type->isFunctionType()) {
      S.Diag(Attr.getLoc(), diag::err_attribute_address_function_type);
      Attr.setInvalid();
      return;
    }
  
    unsigned ASIdx;
    if (Attr.getKind() == AttributeList::AT_AddressSpace) {
      // Check the attribute arguments.
      if (Attr.getNumArgs() != 1) {
        S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments)
          << Attr.getName() << 1;
        Attr.setInvalid();
        return;
      }
      Expr *ASArgExpr = static_cast<Expr *>(Attr.getArgAsExpr(0));
      llvm::APSInt addrSpace(32);
      if (ASArgExpr->isTypeDependent() || ASArgExpr->isValueDependent() ||
          !ASArgExpr->isIntegerConstantExpr(addrSpace, S.Context)) {
        S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
          << Attr.getName() << AANT_ArgumentIntegerConstant
          << ASArgExpr->getSourceRange();
        Attr.setInvalid();
        return;
      }
  
      // Bounds checking.
      if (addrSpace.isSigned()) {
        if (addrSpace.isNegative()) {
          S.Diag(Attr.getLoc(), diag::err_attribute_address_space_negative)
            << ASArgExpr->getSourceRange();
          Attr.setInvalid();
          return;
        }
        addrSpace.setIsSigned(false);
      }
      llvm::APSInt max(addrSpace.getBitWidth());
      max = Qualifiers::MaxAddressSpace;
      if (addrSpace > max) {
        S.Diag(Attr.getLoc(), diag::err_attribute_address_space_too_high)
          << int(Qualifiers::MaxAddressSpace) << ASArgExpr->getSourceRange();
        Attr.setInvalid();
        return;
      }
      ASIdx = static_cast<unsigned>(addrSpace.getZExtValue());
    } else {
      // The keyword-based type attributes imply which address space to use.
      switch (Attr.getKind()) {
      case AttributeList::AT_OpenCLGlobalAddressSpace:
        ASIdx = LangAS::opencl_global; break;
      case AttributeList::AT_OpenCLLocalAddressSpace:
        ASIdx = LangAS::opencl_local; break;
      case AttributeList::AT_OpenCLConstantAddressSpace:
        ASIdx = LangAS::opencl_constant; break;
      default:
        assert(Attr.getKind() == AttributeList::AT_OpenCLPrivateAddressSpace);
        ASIdx = 0; break;
      }
    }
    
    Type = S.Context.getAddrSpaceQualType(Type, ASIdx);
  }
  
  /// Does this type have a "direct" ownership qualifier?  That is,
  /// is it written like "__strong id", as opposed to something like
  /// "typeof(foo)", where that happens to be strong?
  static bool hasDirectOwnershipQualifier(QualType type) {
    // Fast path: no qualifier at all.
    assert(type.getQualifiers().hasObjCLifetime());
  
    while (true) {
      // __strong id
      if (const AttributedType *attr = dyn_cast<AttributedType>(type)) {
        if (attr->getAttrKind() == AttributedType::attr_objc_ownership)
          return true;
  
        type = attr->getModifiedType();
  
      // X *__strong (...)
      } else if (const ParenType *paren = dyn_cast<ParenType>(type)) {
        type = paren->getInnerType();
  
      // That's it for things we want to complain about.  In particular,
      // we do not want to look through typedefs, typeof(expr),
      // typeof(type), or any other way that the type is somehow
      // abstracted.
      } else {
  
        return false;
      }
    }
  }
  
  /// handleObjCOwnershipTypeAttr - Process an objc_ownership
  /// attribute on the specified type.
  ///
  /// Returns 'true' if the attribute was handled.
  static bool handleObjCOwnershipTypeAttr(TypeProcessingState &state,
                                         AttributeList &attr,
                                         QualType &type) {
    bool NonObjCPointer = false;
  
    if (!type->isDependentType() && !type->isUndeducedType()) {
      if (const PointerType *ptr = type->getAs<PointerType>()) {
        QualType pointee = ptr->getPointeeType();
        if (pointee->isObjCRetainableType() || pointee->isPointerType())
          return false;
        // It is important not to lose the source info that there was an attribute
        // applied to non-objc pointer. We will create an attributed type but
        // its type will be the same as the original type.
        NonObjCPointer = true;
      } else if (!type->isObjCRetainableType()) {
        return false;
      }
  
      // Don't accept an ownership attribute in the declspec if it would
      // just be the return type of a block pointer.
      if (state.isProcessingDeclSpec()) {
        Declarator &D = state.getDeclarator();
        if (maybeMovePastReturnType(D, D.getNumTypeObjects()))
          return false;
      }
    }
  
    Sema &S = state.getSema();
    SourceLocation AttrLoc = attr.getLoc();
    if (AttrLoc.isMacroID())
      AttrLoc = S.getSourceManager().getImmediateExpansionRange(AttrLoc).first;
  
    if (!attr.isArgIdent(0)) {
      S.Diag(AttrLoc, diag::err_attribute_argument_type)
        << attr.getName() << AANT_ArgumentString;
      attr.setInvalid();
      return true;
    }
  
    // Consume lifetime attributes without further comment outside of
    // ARC mode.
    if (!S.getLangOpts().ObjCAutoRefCount)
      return true;
  
    IdentifierInfo *II = attr.getArgAsIdent(0)->Ident;
    Qualifiers::ObjCLifetime lifetime;
    if (II->isStr("none"))
      lifetime = Qualifiers::OCL_ExplicitNone;
    else if (II->isStr("strong"))
      lifetime = Qualifiers::OCL_Strong;
    else if (II->isStr("weak"))
      lifetime = Qualifiers::OCL_Weak;
    else if (II->isStr("autoreleasing"))
      lifetime = Qualifiers::OCL_Autoreleasing;
    else {
      S.Diag(AttrLoc, diag::warn_attribute_type_not_supported)
        << attr.getName() << II;
      attr.setInvalid();
      return true;
    }
  
    SplitQualType underlyingType = type.split();
  
    // Check for redundant/conflicting ownership qualifiers.
    if (Qualifiers::ObjCLifetime previousLifetime
          = type.getQualifiers().getObjCLifetime()) {
      // If it's written directly, that's an error.
      if (hasDirectOwnershipQualifier(type)) {
        S.Diag(AttrLoc, diag::err_attr_objc_ownership_redundant)
          << type;
        return true;
      }
  
      // Otherwise, if the qualifiers actually conflict, pull sugar off
      // until we reach a type that is directly qualified.
      if (previousLifetime != lifetime) {
        // This should always terminate: the canonical type is
        // qualified, so some bit of sugar must be hiding it.
        while (!underlyingType.Quals.hasObjCLifetime()) {
          underlyingType = underlyingType.getSingleStepDesugaredType();
        }
        underlyingType.Quals.removeObjCLifetime();
      }
    }
  
    underlyingType.Quals.addObjCLifetime(lifetime);
  
    if (NonObjCPointer) {
      StringRef name = attr.getName()->getName();
      switch (lifetime) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
        break;
      case Qualifiers::OCL_Strong: name = "__strong"; break;
      case Qualifiers::OCL_Weak: name = "__weak"; break;
      case Qualifiers::OCL_Autoreleasing: name = "__autoreleasing"; break;
      }
      S.Diag(AttrLoc, diag::warn_type_attribute_wrong_type) << name
        << TDS_ObjCObjOrBlock << type;
    }
  
    QualType origType = type;
    if (!NonObjCPointer)
      type = S.Context.getQualifiedType(underlyingType);
  
    // If we have a valid source location for the attribute, use an
    // AttributedType instead.
    if (AttrLoc.isValid())
      type = S.Context.getAttributedType(AttributedType::attr_objc_ownership,
                                         origType, type);
  
    // Forbid __weak if the runtime doesn't support it.
    if (lifetime == Qualifiers::OCL_Weak &&
        !S.getLangOpts().ObjCARCWeak && !NonObjCPointer) {
  
      // Actually, delay this until we know what we're parsing.
      if (S.DelayedDiagnostics.shouldDelayDiagnostics()) {
        S.DelayedDiagnostics.add(
            sema::DelayedDiagnostic::makeForbiddenType(
                S.getSourceManager().getExpansionLoc(AttrLoc),
                diag::err_arc_weak_no_runtime, type, /*ignored*/ 0));
      } else {
        S.Diag(AttrLoc, diag::err_arc_weak_no_runtime);
      }
  
      attr.setInvalid();
      return true;
    }
  
    // Forbid __weak for class objects marked as
    // objc_arc_weak_reference_unavailable
    if (lifetime == Qualifiers::OCL_Weak) {
      if (const ObjCObjectPointerType *ObjT =
            type->getAs<ObjCObjectPointerType>()) {
        if (ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl()) {
          if (Class->isArcWeakrefUnavailable()) {
              S.Diag(AttrLoc, diag::err_arc_unsupported_weak_class);
              S.Diag(ObjT->getInterfaceDecl()->getLocation(),
                     diag::note_class_declared);
          }
        }
      }
    }
  
    return true;
  }
  
  /// handleObjCGCTypeAttr - Process the __attribute__((objc_gc)) type
  /// attribute on the specified type.  Returns true to indicate that
  /// the attribute was handled, false to indicate that the type does
  /// not permit the attribute.
  static bool handleObjCGCTypeAttr(TypeProcessingState &state,
                                   AttributeList &attr,
                                   QualType &type) {
    Sema &S = state.getSema();
  
    // Delay if this isn't some kind of pointer.
    if (!type->isPointerType() &&
        !type->isObjCObjectPointerType() &&
        !type->isBlockPointerType())
      return false;
  
    if (type.getObjCGCAttr() != Qualifiers::GCNone) {
      S.Diag(attr.getLoc(), diag::err_attribute_multiple_objc_gc);
      attr.setInvalid();
      return true;
    }
    
    // Check the attribute arguments.
    if (!attr.isArgIdent(0)) {
      S.Diag(attr.getLoc(), diag::err_attribute_argument_type)
        << attr.getName() << AANT_ArgumentString;
      attr.setInvalid();
      return true;
    }
    Qualifiers::GC GCAttr;
    if (attr.getNumArgs() > 1) {
      S.Diag(attr.getLoc(), diag::err_attribute_wrong_number_arguments)
        << attr.getName() << 1;
      attr.setInvalid();
      return true;
    }
  
    IdentifierInfo *II = attr.getArgAsIdent(0)->Ident;
    if (II->isStr("weak"))
      GCAttr = Qualifiers::Weak;
    else if (II->isStr("strong"))
      GCAttr = Qualifiers::Strong;
    else {
      S.Diag(attr.getLoc(), diag::warn_attribute_type_not_supported)
        << attr.getName() << II;
      attr.setInvalid();
      return true;
    }
  
    QualType origType = type;
    type = S.Context.getObjCGCQualType(origType, GCAttr);
  
    // Make an attributed type to preserve the source information.
    if (attr.getLoc().isValid())
      type = S.Context.getAttributedType(AttributedType::attr_objc_gc,
                                         origType, type);
  
    return true;
  }
  
  namespace {
    /// A helper class to unwrap a type down to a function for the
    /// purposes of applying attributes there.
    ///
    /// Use:
    ///   FunctionTypeUnwrapper unwrapped(SemaRef, T);
    ///   if (unwrapped.isFunctionType()) {
    ///     const FunctionType *fn = unwrapped.get();
    ///     // change fn somehow
    ///     T = unwrapped.wrap(fn);
    ///   }
    struct FunctionTypeUnwrapper {
      enum WrapKind {
        Desugar,
        Parens,
        Pointer,
        BlockPointer,
        Reference,
        MemberPointer
      };
  
      QualType Original;
      const FunctionType *Fn;
      SmallVector<unsigned char /*WrapKind*/, 8> Stack;
  
      FunctionTypeUnwrapper(Sema &S, QualType T) : Original(T) {
        while (true) {
          const Type *Ty = T.getTypePtr();
          if (isa<FunctionType>(Ty)) {
            Fn = cast<FunctionType>(Ty);
            return;
          } else if (isa<ParenType>(Ty)) {
            T = cast<ParenType>(Ty)->getInnerType();
            Stack.push_back(Parens);
          } else if (isa<PointerType>(Ty)) {
            T = cast<PointerType>(Ty)->getPointeeType();
            Stack.push_back(Pointer);
          } else if (isa<BlockPointerType>(Ty)) {
            T = cast<BlockPointerType>(Ty)->getPointeeType();
            Stack.push_back(BlockPointer);
          } else if (isa<MemberPointerType>(Ty)) {
            T = cast<MemberPointerType>(Ty)->getPointeeType();
            Stack.push_back(MemberPointer);
          } else if (isa<ReferenceType>(Ty)) {
            T = cast<ReferenceType>(Ty)->getPointeeType();
            Stack.push_back(Reference);
          } else {
            const Type *DTy = Ty->getUnqualifiedDesugaredType();
            if (Ty == DTy) {
              Fn = nullptr;
              return;
            }
  
            T = QualType(DTy, 0);
            Stack.push_back(Desugar);
          }
        }
      }
  
      bool isFunctionType() const { return (Fn != nullptr); }
      const FunctionType *get() const { return Fn; }
  
      QualType wrap(Sema &S, const FunctionType *New) {
        // If T wasn't modified from the unwrapped type, do nothing.
        if (New == get()) return Original;
  
        Fn = New;
        return wrap(S.Context, Original, 0);
      }
  
    private:
      QualType wrap(ASTContext &C, QualType Old, unsigned I) {
        if (I == Stack.size())
          return C.getQualifiedType(Fn, Old.getQualifiers());
  
        // Build up the inner type, applying the qualifiers from the old
        // type to the new type.
        SplitQualType SplitOld = Old.split();
  
        // As a special case, tail-recurse if there are no qualifiers.
        if (SplitOld.Quals.empty())
          return wrap(C, SplitOld.Ty, I);
        return C.getQualifiedType(wrap(C, SplitOld.Ty, I), SplitOld.Quals);
      }
  
      QualType wrap(ASTContext &C, const Type *Old, unsigned I) {
        if (I == Stack.size()) return QualType(Fn, 0);
  
        switch (static_cast<WrapKind>(Stack[I++])) {
        case Desugar:
          // This is the point at which we potentially lose source
          // information.
          return wrap(C, Old->getUnqualifiedDesugaredType(), I);
  
        case Parens: {
          QualType New = wrap(C, cast<ParenType>(Old)->getInnerType(), I);
          return C.getParenType(New);
        }
  
        case Pointer: {
          QualType New = wrap(C, cast<PointerType>(Old)->getPointeeType(), I);
          return C.getPointerType(New);
        }
  
        case BlockPointer: {
          QualType New = wrap(C, cast<BlockPointerType>(Old)->getPointeeType(),I);
          return C.getBlockPointerType(New);
        }
  
        case MemberPointer: {
          const MemberPointerType *OldMPT = cast<MemberPointerType>(Old);
          QualType New = wrap(C, OldMPT->getPointeeType(), I);
          return C.getMemberPointerType(New, OldMPT->getClass());
        }
  
        case Reference: {
          const ReferenceType *OldRef = cast<ReferenceType>(Old);
          QualType New = wrap(C, OldRef->getPointeeType(), I);
          if (isa<LValueReferenceType>(OldRef))
            return C.getLValueReferenceType(New, OldRef->isSpelledAsLValue());
          else
            return C.getRValueReferenceType(New);
        }
        }
  
        llvm_unreachable("unknown wrapping kind");
      }
    };
  }
  
  static bool handleMSPointerTypeQualifierAttr(TypeProcessingState &State,
                                               AttributeList &Attr,
                                               QualType &Type) {
    Sema &S = State.getSema();
  
    AttributeList::Kind Kind = Attr.getKind();
    QualType Desugared = Type;
    const AttributedType *AT = dyn_cast<AttributedType>(Type);
    while (AT) {
      AttributedType::Kind CurAttrKind = AT->getAttrKind();
  
      // You cannot specify duplicate type attributes, so if the attribute has
      // already been applied, flag it.
      if (getAttrListKind(CurAttrKind) == Kind) {
        S.Diag(Attr.getLoc(), diag::warn_duplicate_attribute_exact)
          << Attr.getName();
        return true;
      }
  
      // You cannot have both __sptr and __uptr on the same type, nor can you
      // have __ptr32 and __ptr64.
      if ((CurAttrKind == AttributedType::attr_ptr32 &&
           Kind == AttributeList::AT_Ptr64) ||
          (CurAttrKind == AttributedType::attr_ptr64 &&
           Kind == AttributeList::AT_Ptr32)) {
        S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
          << "'__ptr32'" << "'__ptr64'";
        return true;
      } else if ((CurAttrKind == AttributedType::attr_sptr &&
                  Kind == AttributeList::AT_UPtr) ||
                 (CurAttrKind == AttributedType::attr_uptr &&
                  Kind == AttributeList::AT_SPtr)) {
        S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
          << "'__sptr'" << "'__uptr'";
        return true;
      }
      
      Desugared = AT->getEquivalentType();
      AT = dyn_cast<AttributedType>(Desugared);
    }
  
    // Pointer type qualifiers can only operate on pointer types, but not
    // pointer-to-member types.
    if (!isa<PointerType>(Desugared)) {
      S.Diag(Attr.getLoc(), Type->isMemberPointerType() ?
                            diag::err_attribute_no_member_pointers :
                            diag::err_attribute_pointers_only) << Attr.getName();
      return true;
    }
  
    AttributedType::Kind TAK;
    switch (Kind) {
    default: llvm_unreachable("Unknown attribute kind");
    case AttributeList::AT_Ptr32: TAK = AttributedType::attr_ptr32; break;
    case AttributeList::AT_Ptr64: TAK = AttributedType::attr_ptr64; break;
    case AttributeList::AT_SPtr: TAK = AttributedType::attr_sptr; break;
    case AttributeList::AT_UPtr: TAK = AttributedType::attr_uptr; break;
    }
  
    Type = S.Context.getAttributedType(TAK, Type, Type);
    return false;
  }
  
  static AttributedType::Kind getCCTypeAttrKind(AttributeList &Attr) {
    assert(!Attr.isInvalid());
    switch (Attr.getKind()) {
    default:
      llvm_unreachable("not a calling convention attribute");
    case AttributeList::AT_CDecl:
      return AttributedType::attr_cdecl;
    case AttributeList::AT_FastCall:
      return AttributedType::attr_fastcall;
    case AttributeList::AT_StdCall:
      return AttributedType::attr_stdcall;
    case AttributeList::AT_ThisCall:
      return AttributedType::attr_thiscall;
    case AttributeList::AT_Pascal:
      return AttributedType::attr_pascal;
    case AttributeList::AT_Pcs: {
      // The attribute may have had a fixit applied where we treated an
      // identifier as a string literal.  The contents of the string are valid,
      // but the form may not be.
      StringRef Str;
      if (Attr.isArgExpr(0))
        Str = cast<StringLiteral>(Attr.getArgAsExpr(0))->getString();
      else
        Str = Attr.getArgAsIdent(0)->Ident->getName();
      return llvm::StringSwitch<AttributedType::Kind>(Str)
          .Case("aapcs", AttributedType::attr_pcs)
          .Case("aapcs-vfp", AttributedType::attr_pcs_vfp);
    }
    case AttributeList::AT_PnaclCall:
      return AttributedType::attr_pnaclcall;
    case AttributeList::AT_IntelOclBicc:
      return AttributedType::attr_inteloclbicc;
    case AttributeList::AT_MSABI:
      return AttributedType::attr_ms_abi;
    case AttributeList::AT_SysVABI:
      return AttributedType::attr_sysv_abi;
    }
    llvm_unreachable("unexpected attribute kind!");
  }
  
  /// Process an individual function attribute.  Returns true to
  /// indicate that the attribute was handled, false if it wasn't.
  static bool handleFunctionTypeAttr(TypeProcessingState &state,
                                     AttributeList &attr,
                                     QualType &type) {
    Sema &S = state.getSema();
  
    FunctionTypeUnwrapper unwrapped(S, type);
  
    if (attr.getKind() == AttributeList::AT_NoReturn) {
      if (S.CheckNoReturnAttr(attr))
        return true;
  
      // Delay if this is not a function type.
      if (!unwrapped.isFunctionType())
        return false;
  
      // Otherwise we can process right away.
      FunctionType::ExtInfo EI = unwrapped.get()->getExtInfo().withNoReturn(true);
      type = unwrapped.wrap(S, S.Context.adjustFunctionType(unwrapped.get(), EI));
      return true;
    }
  
    // ns_returns_retained is not always a type attribute, but if we got
    // here, we're treating it as one right now.
    if (attr.getKind() == AttributeList::AT_NSReturnsRetained) {
      assert(S.getLangOpts().ObjCAutoRefCount &&
             "ns_returns_retained treated as type attribute in non-ARC");
      if (attr.getNumArgs()) return true;
  
      // Delay if this is not a function type.
      if (!unwrapped.isFunctionType())
        return false;
  
      FunctionType::ExtInfo EI
        = unwrapped.get()->getExtInfo().withProducesResult(true);
      type = unwrapped.wrap(S, S.Context.adjustFunctionType(unwrapped.get(), EI));
      return true;
    }
  
    if (attr.getKind() == AttributeList::AT_Regparm) {
      unsigned value;
      if (S.CheckRegparmAttr(attr, value))
        return true;
  
      // Delay if this is not a function type.
      if (!unwrapped.isFunctionType())
        return false;
  
      // Diagnose regparm with fastcall.
      const FunctionType *fn = unwrapped.get();
      CallingConv CC = fn->getCallConv();
      if (CC == CC_X86FastCall) {
        S.Diag(attr.getLoc(), diag::err_attributes_are_not_compatible)
          << FunctionType::getNameForCallConv(CC)
          << "regparm";
        attr.setInvalid();
        return true;
      }
  
      FunctionType::ExtInfo EI =
        unwrapped.get()->getExtInfo().withRegParm(value);
      type = unwrapped.wrap(S, S.Context.adjustFunctionType(unwrapped.get(), EI));
      return true;
    }
  
    // Delay if the type didn't work out to a function.
    if (!unwrapped.isFunctionType()) return false;
  
    // Otherwise, a calling convention.
    CallingConv CC;
    if (S.CheckCallingConvAttr(attr, CC))
      return true;
  
    const FunctionType *fn = unwrapped.get();
    CallingConv CCOld = fn->getCallConv();
    AttributedType::Kind CCAttrKind = getCCTypeAttrKind(attr);
  
    if (CCOld != CC) {
      // Error out on when there's already an attribute on the type
      // and the CCs don't match.
      const AttributedType *AT = S.getCallingConvAttributedType(type);
      if (AT && AT->getAttrKind() != CCAttrKind) {
        S.Diag(attr.getLoc(), diag::err_attributes_are_not_compatible)
          << FunctionType::getNameForCallConv(CC)
          << FunctionType::getNameForCallConv(CCOld);
        attr.setInvalid();
        return true;
      }
    }
  
    // Diagnose use of callee-cleanup calling convention on variadic functions.
    if (isCalleeCleanup(CC)) {
      const FunctionProtoType *FnP = dyn_cast<FunctionProtoType>(fn);
      if (FnP && FnP->isVariadic()) {
        unsigned DiagID = diag::err_cconv_varargs;
        // stdcall and fastcall are ignored with a warning for GCC and MS
        // compatibility.
        if (CC == CC_X86StdCall || CC == CC_X86FastCall)
          DiagID = diag::warn_cconv_varargs;
  
        S.Diag(attr.getLoc(), DiagID) << FunctionType::getNameForCallConv(CC);
        attr.setInvalid();
        return true;
      }
    }
  
    // Diagnose the use of X86 fastcall on unprototyped functions.
    if (CC == CC_X86FastCall) {
      if (isa<FunctionNoProtoType>(fn)) {
        S.Diag(attr.getLoc(), diag::err_cconv_knr)
          << FunctionType::getNameForCallConv(CC);
        attr.setInvalid();
        return true;
      }
  
      // Also diagnose fastcall with regparm.
      if (fn->getHasRegParm()) {
        S.Diag(attr.getLoc(), diag::err_attributes_are_not_compatible)
          << "regparm"
          << FunctionType::getNameForCallConv(CC);
        attr.setInvalid();
        return true;
      }
    }
  
    // Modify the CC from the wrapped function type, wrap it all back, and then
    // wrap the whole thing in an AttributedType as written.  The modified type
    // might have a different CC if we ignored the attribute.
    FunctionType::ExtInfo EI = unwrapped.get()->getExtInfo().withCallingConv(CC);
    QualType Equivalent =
        unwrapped.wrap(S, S.Context.adjustFunctionType(unwrapped.get(), EI));
    type = S.Context.getAttributedType(CCAttrKind, type, Equivalent);
    return true;
  }
  
  bool Sema::hasExplicitCallingConv(QualType &T) {
    QualType R = T.IgnoreParens();
    while (const AttributedType *AT = dyn_cast<AttributedType>(R)) {
      if (AT->isCallingConv())
        return true;
      R = AT->getModifiedType().IgnoreParens();
    }
    return false;
  }
  
  void Sema::adjustMemberFunctionCC(QualType &T, bool IsStatic) {
    FunctionTypeUnwrapper Unwrapped(*this, T);
    const FunctionType *FT = Unwrapped.get();
    bool IsVariadic = (isa<FunctionProtoType>(FT) &&
                       cast<FunctionProtoType>(FT)->isVariadic());
  
    // Only adjust types with the default convention.  For example, on Windows we
    // should adjust a __cdecl type to __thiscall for instance methods, and a
    // __thiscall type to __cdecl for static methods.
    CallingConv CurCC = FT->getCallConv();
    CallingConv FromCC =
        Context.getDefaultCallingConvention(IsVariadic, IsStatic);
    CallingConv ToCC = Context.getDefaultCallingConvention(IsVariadic, !IsStatic);
    if (CurCC != FromCC || FromCC == ToCC)
      return;
  
    if (hasExplicitCallingConv(T))
      return;
  
    FT = Context.adjustFunctionType(FT, FT->getExtInfo().withCallingConv(ToCC));
    QualType Wrapped = Unwrapped.wrap(*this, FT);
    T = Context.getAdjustedType(T, Wrapped);
  }
  
  /// HandleVectorSizeAttribute - this attribute is only applicable to integral
  /// and float scalars, although arrays, pointers, and function return values are
  /// allowed in conjunction with this construct. Aggregates with this attribute
  /// are invalid, even if they are of the same size as a corresponding scalar.
  /// The raw attribute should contain precisely 1 argument, the vector size for
  /// the variable, measured in bytes. If curType and rawAttr are well formed,
  /// this routine will return a new vector type.
  static void HandleVectorSizeAttr(QualType& CurType, const AttributeList &Attr,
                                   Sema &S) {
    // Check the attribute arguments.
    if (Attr.getNumArgs() != 1) {
      S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments)
        << Attr.getName() << 1;
      Attr.setInvalid();
      return;
    }
    Expr *sizeExpr = static_cast<Expr *>(Attr.getArgAsExpr(0));
    llvm::APSInt vecSize(32);
    if (sizeExpr->isTypeDependent() || sizeExpr->isValueDependent() ||
        !sizeExpr->isIntegerConstantExpr(vecSize, S.Context)) {
      S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
        << Attr.getName() << AANT_ArgumentIntegerConstant
        << sizeExpr->getSourceRange();
      Attr.setInvalid();
      return;
    }
    // The base type must be integer (not Boolean or enumeration) or float, and
    // can't already be a vector.
    if (!CurType->isBuiltinType() || CurType->isBooleanType() ||
        (!CurType->isIntegerType() && !CurType->isRealFloatingType())) {
      S.Diag(Attr.getLoc(), diag::err_attribute_invalid_vector_type) << CurType;
      Attr.setInvalid();
      return;
    }
    unsigned typeSize = static_cast<unsigned>(S.Context.getTypeSize(CurType));
    // vecSize is specified in bytes - convert to bits.
    unsigned vectorSize = static_cast<unsigned>(vecSize.getZExtValue() * 8);
  
    // the vector size needs to be an integral multiple of the type size.
    if (vectorSize % typeSize) {
      S.Diag(Attr.getLoc(), diag::err_attribute_invalid_size)
        << sizeExpr->getSourceRange();
      Attr.setInvalid();
      return;
    }
    if (VectorType::isVectorSizeTooLarge(vectorSize / typeSize)) {
      S.Diag(Attr.getLoc(), diag::err_attribute_size_too_large)
        << sizeExpr->getSourceRange();
      Attr.setInvalid();
      return;
    }
    if (vectorSize == 0) {
      S.Diag(Attr.getLoc(), diag::err_attribute_zero_size)
        << sizeExpr->getSourceRange();
      Attr.setInvalid();
      return;
    }
  
    // Success! Instantiate the vector type, the number of elements is > 0, and
    // not required to be a power of 2, unlike GCC.
    CurType = S.Context.getVectorType(CurType, vectorSize/typeSize,
                                      VectorType::GenericVector);
  }
  
  /// \brief Process the OpenCL-like ext_vector_type attribute when it occurs on
  /// a type.
  static void HandleExtVectorTypeAttr(QualType &CurType,
                                      const AttributeList &Attr,
                                      Sema &S) {
    // check the attribute arguments.
    if (Attr.getNumArgs() != 1) {
      S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments)
        << Attr.getName() << 1;
      return;
    }
  
    Expr *sizeExpr;
  
    // Special case where the argument is a template id.
    if (Attr.isArgIdent(0)) {
      CXXScopeSpec SS;
      SourceLocation TemplateKWLoc;
      UnqualifiedId id;
      id.setIdentifier(Attr.getArgAsIdent(0)->Ident, Attr.getLoc());
  
      ExprResult Size = S.ActOnIdExpression(S.getCurScope(), SS, TemplateKWLoc,
                                            id, false, false);
      if (Size.isInvalid())
        return;
  
      sizeExpr = Size.get();
    } else {
      sizeExpr = Attr.getArgAsExpr(0);
    }
  
    // Create the vector type.
    QualType T = S.BuildExtVectorType(CurType, sizeExpr, Attr.getLoc());
    if (!T.isNull())
      CurType = T;
  }
  
  static bool isPermittedNeonBaseType(QualType &Ty,
                                      VectorType::VectorKind VecKind, Sema &S) {
    const BuiltinType *BTy = Ty->getAs<BuiltinType>();
    if (!BTy)
      return false;
  
    llvm::Triple Triple = S.Context.getTargetInfo().getTriple();
  
    // Signed poly is mathematically wrong, but has been baked into some ABIs by
    // now.
    bool IsPolyUnsigned = Triple.getArch() == llvm::Triple::aarch64 ||
                          Triple.getArch() == llvm::Triple::aarch64_be ||
                          Triple.getArch() == llvm::Triple::arm64 ||
                          Triple.getArch() == llvm::Triple::arm64_be;
    if (VecKind == VectorType::NeonPolyVector) {
      if (IsPolyUnsigned) {
        // AArch64 polynomial vectors are unsigned and support poly64.
        return BTy->getKind() == BuiltinType::UChar ||
               BTy->getKind() == BuiltinType::UShort ||
               BTy->getKind() == BuiltinType::ULong ||
               BTy->getKind() == BuiltinType::ULongLong;
      } else {
        // AArch32 polynomial vector are signed.
        return BTy->getKind() == BuiltinType::SChar ||
               BTy->getKind() == BuiltinType::Short;
      }
    }
  
    // Non-polynomial vector types: the usual suspects are allowed, as well as
    // float64_t on AArch64.
    bool Is64Bit = Triple.getArch() == llvm::Triple::aarch64 ||
                   Triple.getArch() == llvm::Triple::aarch64_be ||
                   Triple.getArch() == llvm::Triple::arm64 ||
                   Triple.getArch() == llvm::Triple::arm64_be;
  
    if (Is64Bit && BTy->getKind() == BuiltinType::Double)
      return true;
  
    return BTy->getKind() == BuiltinType::SChar ||
           BTy->getKind() == BuiltinType::UChar ||
           BTy->getKind() == BuiltinType::Short ||
           BTy->getKind() == BuiltinType::UShort ||
           BTy->getKind() == BuiltinType::Int ||
           BTy->getKind() == BuiltinType::UInt ||
           BTy->getKind() == BuiltinType::Long ||
           BTy->getKind() == BuiltinType::ULong ||
           BTy->getKind() == BuiltinType::LongLong ||
           BTy->getKind() == BuiltinType::ULongLong ||
           BTy->getKind() == BuiltinType::Float ||
           BTy->getKind() == BuiltinType::Half;
  }
  
  /// HandleNeonVectorTypeAttr - The "neon_vector_type" and
  /// "neon_polyvector_type" attributes are used to create vector types that
  /// are mangled according to ARM's ABI.  Otherwise, these types are identical
  /// to those created with the "vector_size" attribute.  Unlike "vector_size"
  /// the argument to these Neon attributes is the number of vector elements,
  /// not the vector size in bytes.  The vector width and element type must
  /// match one of the standard Neon vector types.
  static void HandleNeonVectorTypeAttr(QualType& CurType,
                                       const AttributeList &Attr, Sema &S,
                                       VectorType::VectorKind VecKind) {
    // Target must have NEON
    if (!S.Context.getTargetInfo().hasFeature("neon")) {
      S.Diag(Attr.getLoc(), diag::err_attribute_unsupported) << Attr.getName();
      Attr.setInvalid();
      return;
    }
    // Check the attribute arguments.
    if (Attr.getNumArgs() != 1) {
      S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments)
        << Attr.getName() << 1;
      Attr.setInvalid();
      return;
    }
    // The number of elements must be an ICE.
    Expr *numEltsExpr = static_cast<Expr *>(Attr.getArgAsExpr(0));
    llvm::APSInt numEltsInt(32);
    if (numEltsExpr->isTypeDependent() || numEltsExpr->isValueDependent() ||
        !numEltsExpr->isIntegerConstantExpr(numEltsInt, S.Context)) {
      S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
        << Attr.getName() << AANT_ArgumentIntegerConstant
        << numEltsExpr->getSourceRange();
      Attr.setInvalid();
      return;
    }
    // Only certain element types are supported for Neon vectors.
    if (!isPermittedNeonBaseType(CurType, VecKind, S)) {
      S.Diag(Attr.getLoc(), diag::err_attribute_invalid_vector_type) << CurType;
      Attr.setInvalid();
      return;
    }
  
    // The total size of the vector must be 64 or 128 bits.
    unsigned typeSize = static_cast<unsigned>(S.Context.getTypeSize(CurType));
    unsigned numElts = static_cast<unsigned>(numEltsInt.getZExtValue());
    unsigned vecSize = typeSize * numElts;
    if (vecSize != 64 && vecSize != 128) {
      S.Diag(Attr.getLoc(), diag::err_attribute_bad_neon_vector_size) << CurType;
      Attr.setInvalid();
      return;
    }
  
    CurType = S.Context.getVectorType(CurType, numElts, VecKind);
  }
  
  static void processTypeAttrs(TypeProcessingState &state, QualType &type,
                               TypeAttrLocation TAL, AttributeList *attrs) {
    // Scan through and apply attributes to this type where it makes sense.  Some
    // attributes (such as __address_space__, __vector_size__, etc) apply to the
    // type, but others can be present in the type specifiers even though they
    // apply to the decl.  Here we apply type attributes and ignore the rest.
  
    AttributeList *next;
    do {
      AttributeList &attr = *attrs;
      next = attr.getNext();
  
      // Skip attributes that were marked to be invalid.
      if (attr.isInvalid())
        continue;
  
      if (attr.isCXX11Attribute()) {
        // [[gnu::...]] attributes are treated as declaration attributes, so may
        // not appertain to a DeclaratorChunk, even if we handle them as type
        // attributes.
        if (attr.getScopeName() && attr.getScopeName()->isStr("gnu")) {
          if (TAL == TAL_DeclChunk) {
            state.getSema().Diag(attr.getLoc(),
                                 diag::warn_cxx11_gnu_attribute_on_type)
                << attr.getName();
            continue;
          }
        } else if (TAL != TAL_DeclChunk) {
          // Otherwise, only consider type processing for a C++11 attribute if
          // it's actually been applied to a type.
          continue;
        }
      }
  
      // If this is an attribute we can handle, do so now,
      // otherwise, add it to the FnAttrs list for rechaining.
      switch (attr.getKind()) {
      default:
        // A C++11 attribute on a declarator chunk must appertain to a type.
        if (attr.isCXX11Attribute() && TAL == TAL_DeclChunk) {
          state.getSema().Diag(attr.getLoc(), diag::err_attribute_not_type_attr)
            << attr.getName();
          attr.setUsedAsTypeAttr();
        }
        break;
  
      case AttributeList::UnknownAttribute:
        if (attr.isCXX11Attribute() && TAL == TAL_DeclChunk)
          state.getSema().Diag(attr.getLoc(),
                               diag::warn_unknown_attribute_ignored)
            << attr.getName();
        break;
  
      case AttributeList::IgnoredAttribute:
        break;
  
      case AttributeList::AT_MayAlias:
        // FIXME: This attribute needs to actually be handled, but if we ignore
        // it it breaks large amounts of Linux software.
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_OpenCLPrivateAddressSpace:
      case AttributeList::AT_OpenCLGlobalAddressSpace:
      case AttributeList::AT_OpenCLLocalAddressSpace:
      case AttributeList::AT_OpenCLConstantAddressSpace:
      case AttributeList::AT_AddressSpace:
        HandleAddressSpaceTypeAttribute(type, attr, state.getSema());
        attr.setUsedAsTypeAttr();
        break;
      OBJC_POINTER_TYPE_ATTRS_CASELIST:
        if (!handleObjCPointerTypeAttr(state, attr, type))
          distributeObjCPointerTypeAttr(state, attr, type);
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_VectorSize:
        HandleVectorSizeAttr(type, attr, state.getSema());
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_ExtVectorType:
        HandleExtVectorTypeAttr(type, attr, state.getSema());
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_NeonVectorType:
        HandleNeonVectorTypeAttr(type, attr, state.getSema(),
                                 VectorType::NeonVector);
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_NeonPolyVectorType:
        HandleNeonVectorTypeAttr(type, attr, state.getSema(),
                                 VectorType::NeonPolyVector);
        attr.setUsedAsTypeAttr();
        break;
      case AttributeList::AT_OpenCLImageAccess:
        // FIXME: there should be some type checking happening here, I would
        // imagine, but the original handler's checking was entirely superfluous.
        attr.setUsedAsTypeAttr();
        break;
  
      MS_TYPE_ATTRS_CASELIST:
        if (!handleMSPointerTypeQualifierAttr(state, attr, type))
          attr.setUsedAsTypeAttr();
        break;
  
      case AttributeList::AT_NSReturnsRetained:
        if (!state.getSema().getLangOpts().ObjCAutoRefCount)
          break;
        // fallthrough into the function attrs
  
      FUNCTION_TYPE_ATTRS_CASELIST:
        attr.setUsedAsTypeAttr();
  
        // Never process function type attributes as part of the
        // declaration-specifiers.
        if (TAL == TAL_DeclSpec)
          distributeFunctionTypeAttrFromDeclSpec(state, attr, type);
  
        // Otherwise, handle the possible delays.
        else if (!handleFunctionTypeAttr(state, attr, type))
          distributeFunctionTypeAttr(state, attr, type);
        break;
      }
    } while ((attrs = next));
  }
  
  /// \brief Ensure that the type of the given expression is complete.
  ///
  /// This routine checks whether the expression \p E has a complete type. If the
  /// expression refers to an instantiable construct, that instantiation is
  /// performed as needed to complete its type. Furthermore
  /// Sema::RequireCompleteType is called for the expression's type (or in the
  /// case of a reference type, the referred-to type).
  ///
  /// \param E The expression whose type is required to be complete.
  /// \param Diagnoser The object that will emit a diagnostic if the type is
  /// incomplete.
  ///
  /// \returns \c true if the type of \p E is incomplete and diagnosed, \c false
  /// otherwise.
  bool Sema::RequireCompleteExprType(Expr *E, TypeDiagnoser &Diagnoser){
    QualType T = E->getType();
  
    // Fast path the case where the type is already complete.
    if (!T->isIncompleteType())
      // FIXME: The definition might not be visible.
      return false;
  
    // Incomplete array types may be completed by the initializer attached to
    // their definitions. For static data members of class templates and for
    // variable templates, we need to instantiate the definition to get this
    // initializer and complete the type.
    if (T->isIncompleteArrayType()) {
      if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
        if (VarDecl *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
          if (isTemplateInstantiation(Var->getTemplateSpecializationKind())) {
            SourceLocation PointOfInstantiation = E->getExprLoc();
  
            if (MemberSpecializationInfo *MSInfo =
                    Var->getMemberSpecializationInfo()) {
              // If we don't already have a point of instantiation, this is it.
              if (MSInfo->getPointOfInstantiation().isInvalid()) {
                MSInfo->setPointOfInstantiation(PointOfInstantiation);
  
                // This is a modification of an existing AST node. Notify
                // listeners.
                if (ASTMutationListener *L = getASTMutationListener())
                  L->StaticDataMemberInstantiated(Var);
              }
            } else {
              VarTemplateSpecializationDecl *VarSpec =
                  cast<VarTemplateSpecializationDecl>(Var);
              if (VarSpec->getPointOfInstantiation().isInvalid())
                VarSpec->setPointOfInstantiation(PointOfInstantiation);
            }
  
            InstantiateVariableDefinition(PointOfInstantiation, Var);
  
            // Update the type to the newly instantiated definition's type both
            // here and within the expression.
            if (VarDecl *Def = Var->getDefinition()) {
              DRE->setDecl(Def);
              T = Def->getType();
              DRE->setType(T);
              E->setType(T);
            }
  
            // We still go on to try to complete the type independently, as it
            // may also require instantiations or diagnostics if it remains
            // incomplete.
          }
        }
      }
    }
  
    // FIXME: Are there other cases which require instantiating something other
    // than the type to complete the type of an expression?
  
    // Look through reference types and complete the referred type.
    if (const ReferenceType *Ref = T->getAs<ReferenceType>())
      T = Ref->getPointeeType();
  
    return RequireCompleteType(E->getExprLoc(), T, Diagnoser);
  }
  
  namespace {
    struct TypeDiagnoserDiag : Sema::TypeDiagnoser {
      unsigned DiagID;
  
      TypeDiagnoserDiag(unsigned DiagID)
        : Sema::TypeDiagnoser(DiagID == 0), DiagID(DiagID) {}
  
      void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
        if (Suppressed) return;
        S.Diag(Loc, DiagID) << T;
      }
    };
  }
  
  bool Sema::RequireCompleteExprType(Expr *E, unsigned DiagID) {
    TypeDiagnoserDiag Diagnoser(DiagID);
    return RequireCompleteExprType(E, Diagnoser);
  }
  
  /// @brief Ensure that the type T is a complete type.
  ///
  /// This routine checks whether the type @p T is complete in any
  /// context where a complete type is required. If @p T is a complete
  /// type, returns false. If @p T is a class template specialization,
  /// this routine then attempts to perform class template
  /// instantiation. If instantiation fails, or if @p T is incomplete
  /// and cannot be completed, issues the diagnostic @p diag (giving it
  /// the type @p T) and returns true.
  ///
  /// @param Loc  The location in the source that the incomplete type
  /// diagnostic should refer to.
  ///
  /// @param T  The type that this routine is examining for completeness.
  ///
  /// @returns @c true if @p T is incomplete and a diagnostic was emitted,
  /// @c false otherwise.
  bool Sema::RequireCompleteType(SourceLocation Loc, QualType T,
                                 TypeDiagnoser &Diagnoser) {
    if (RequireCompleteTypeImpl(Loc, T, Diagnoser))
      return true;
    if (const TagType *Tag = T->getAs<TagType>()) {
      if (!Tag->getDecl()->isCompleteDefinitionRequired()) {
        Tag->getDecl()->setCompleteDefinitionRequired();
        Consumer.HandleTagDeclRequiredDefinition(Tag->getDecl());
      }
    }
    return false;
  }
  
  /// \brief Determine whether there is any declaration of \p D that was ever a
  ///        definition (perhaps before module merging) and is currently visible.
  /// \param D The definition of the entity.
  /// \param Suggested Filled in with the declaration that should be made visible
  ///        in order to provide a definition of this entity.
  static bool hasVisibleDefinition(Sema &S, NamedDecl *D, NamedDecl **Suggested) {
    // Easy case: if we don't have modules, all declarations are visible.
    if (!S.getLangOpts().Modules)
      return true;
  
    // If this definition was instantiated from a template, map back to the
    // pattern from which it was instantiated.
    //
    // FIXME: There must be a better place for this to live.
    if (auto *RD = dyn_cast<CXXRecordDecl>(D)) {
      if (auto *TD = dyn_cast<ClassTemplateSpecializationDecl>(RD)) {
        auto From = TD->getInstantiatedFrom();
        if (auto *CTD = From.dyn_cast<ClassTemplateDecl*>()) {
          while (auto *NewCTD = CTD->getInstantiatedFromMemberTemplate()) {
            if (NewCTD->isMemberSpecialization())
              break;
            CTD = NewCTD;
          }
          RD = CTD->getTemplatedDecl();
        } else if (auto *CTPSD = From.dyn_cast<
                       ClassTemplatePartialSpecializationDecl *>()) {
          while (auto *NewCTPSD = CTPSD->getInstantiatedFromMember()) {
            if (NewCTPSD->isMemberSpecialization())
              break;
            CTPSD = NewCTPSD;
          }
          RD = CTPSD;
        }
      } else if (isTemplateInstantiation(RD->getTemplateSpecializationKind())) {
        while (auto *NewRD = RD->getInstantiatedFromMemberClass())
          RD = NewRD;
      }
      D = RD->getDefinition();
    } else if (auto *ED = dyn_cast<EnumDecl>(D)) {
      while (auto *NewED = ED->getInstantiatedFromMemberEnum())
        ED = NewED;
      if (ED->isFixed()) {
        // If the enum has a fixed underlying type, any declaration of it will do.
        *Suggested = nullptr;
        for (auto *Redecl : ED->redecls()) {
          if (LookupResult::isVisible(S, Redecl))
            return true;
          if (Redecl->isThisDeclarationADefinition() ||
              (Redecl->isCanonicalDecl() && !*Suggested))
            *Suggested = Redecl;
        }
        return false;
      }
      D = ED->getDefinition();
    }
    assert(D && "missing definition for pattern of instantiated definition");
  
    // FIXME: If we merged any other decl into D, and that declaration is visible,
    // then we should consider a definition to be visible.
    *Suggested = D;
    return LookupResult::isVisible(S, D);
  }
  
  /// Locks in the inheritance model for the given class and all of its bases.
  static void assignInheritanceModel(Sema &S, CXXRecordDecl *RD) {
    RD = RD->getMostRecentDecl();
    if (!RD->hasAttr<MSInheritanceAttr>()) {
      MSInheritanceAttr::Spelling IM;
  
      switch (S.MSPointerToMemberRepresentationMethod) {
      case LangOptions::PPTMK_BestCase:
        IM = RD->calculateInheritanceModel();
        break;
      case LangOptions::PPTMK_FullGeneralitySingleInheritance:
        IM = MSInheritanceAttr::Keyword_single_inheritance;
        break;
      case LangOptions::PPTMK_FullGeneralityMultipleInheritance:
        IM = MSInheritanceAttr::Keyword_multiple_inheritance;
        break;
      case LangOptions::PPTMK_FullGeneralityVirtualInheritance:
        IM = MSInheritanceAttr::Keyword_unspecified_inheritance;
        break;
      }
  
      RD->addAttr(MSInheritanceAttr::CreateImplicit(
          S.getASTContext(), IM,
          /*BestCase=*/S.MSPointerToMemberRepresentationMethod ==
              LangOptions::PPTMK_BestCase,
          S.ImplicitMSInheritanceAttrLoc.isValid()
              ? S.ImplicitMSInheritanceAttrLoc
              : RD->getSourceRange()));
    }
  
    if (RD->hasDefinition()) {
      // Assign inheritance models to all of the base classes, because now we can
      // form pointers to members of base classes without calling
      // RequireCompleteType on the pointer to member of the base class type.
      for (const CXXBaseSpecifier &BS : RD->bases())
        assignInheritanceModel(S, BS.getType()->getAsCXXRecordDecl());
    }
  }
  
  /// \brief The implementation of RequireCompleteType
  bool Sema::RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
                                     TypeDiagnoser &Diagnoser) {
    // FIXME: Add this assertion to make sure we always get instantiation points.
    //  assert(!Loc.isInvalid() && "Invalid location in RequireCompleteType");
    // FIXME: Add this assertion to help us flush out problems with
    // checking for dependent types and type-dependent expressions.
    //
    //  assert(!T->isDependentType() &&
    //         "Can't ask whether a dependent type is complete");
  
    // If we have a complete type, we're done.
    NamedDecl *Def = nullptr;
    if (!T->isIncompleteType(&Def)) {
      // If we know about the definition but it is not visible, complain.
      NamedDecl *SuggestedDef = nullptr;
      if (!Diagnoser.Suppressed && Def &&
          !hasVisibleDefinition(*this, Def, &SuggestedDef)) {
        // Suppress this error outside of a SFINAE context if we've already
        // emitted the error once for this type. There's no usefulness in
        // repeating the diagnostic.
        // FIXME: Add a Fix-It that imports the corresponding module or includes
        // the header.
        Module *Owner = SuggestedDef->getOwningModule();
        Diag(Loc, diag::err_module_private_definition)
          << T << Owner->getFullModuleName();
        Diag(SuggestedDef->getLocation(), diag::note_previous_definition);
  
        // Try to recover by implicitly importing this module.
        createImplicitModuleImportForErrorRecovery(Loc, Owner);
      }
  
      // We lock in the inheritance model once somebody has asked us to ensure
      // that a pointer-to-member type is complete.
      if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
        if (const MemberPointerType *MPTy = T->getAs<MemberPointerType>()) {
          if (!MPTy->getClass()->isDependentType()) {
            RequireCompleteType(Loc, QualType(MPTy->getClass(), 0), 0);
            assignInheritanceModel(*this, MPTy->getMostRecentCXXRecordDecl());
          }
        }
      }
  
      return false;
    }
  
    const TagType *Tag = T->getAs<TagType>();
    const ObjCInterfaceType *IFace = T->getAs<ObjCInterfaceType>();
  
    // If there's an unimported definition of this type in a module (for
    // instance, because we forward declared it, then imported the definition),
    // import that definition now.
    //
    // FIXME: What about other cases where an import extends a redeclaration
    // chain for a declaration that can be accessed through a mechanism other
    // than name lookup (eg, referenced in a template, or a variable whose type
    // could be completed by the module)?
    if (Tag || IFace) {
      NamedDecl *D =
          Tag ? static_cast<NamedDecl *>(Tag->getDecl()) : IFace->getDecl();
  
      // Avoid diagnosing invalid decls as incomplete.
      if (D->isInvalidDecl())
        return true;
  
      // Give the external AST source a chance to complete the type.
      if (auto *Source = Context.getExternalSource()) {
        if (Tag)
          Source->CompleteType(Tag->getDecl());
        else
          Source->CompleteType(IFace->getDecl());
  
        // If the external source completed the type, go through the motions
        // again to ensure we're allowed to use the completed type.
        if (!T->isIncompleteType())
          return RequireCompleteTypeImpl(Loc, T, Diagnoser);
      }
    }
  
    // If we have a class template specialization or a class member of a
    // class template specialization, or an array with known size of such,
    // try to instantiate it.
    QualType MaybeTemplate = T;
    while (const ConstantArrayType *Array
             = Context.getAsConstantArrayType(MaybeTemplate))
      MaybeTemplate = Array->getElementType();
    if (const RecordType *Record = MaybeTemplate->getAs<RecordType>()) {
      if (ClassTemplateSpecializationDecl *ClassTemplateSpec
            = dyn_cast<ClassTemplateSpecializationDecl>(Record->getDecl())) {
        if (ClassTemplateSpec->getSpecializationKind() == TSK_Undeclared)
          return InstantiateClassTemplateSpecialization(Loc, ClassTemplateSpec,
                                                        TSK_ImplicitInstantiation,
                                              /*Complain=*/!Diagnoser.Suppressed);
      } else if (CXXRecordDecl *Rec
                   = dyn_cast<CXXRecordDecl>(Record->getDecl())) {
        CXXRecordDecl *Pattern = Rec->getInstantiatedFromMemberClass();
        if (!Rec->isBeingDefined() && Pattern) {
          MemberSpecializationInfo *MSI = Rec->getMemberSpecializationInfo();
          assert(MSI && "Missing member specialization information?");
          // This record was instantiated from a class within a template.
          if (MSI->getTemplateSpecializationKind() != TSK_ExplicitSpecialization)
            return InstantiateClass(Loc, Rec, Pattern,
                                    getTemplateInstantiationArgs(Rec),
                                    TSK_ImplicitInstantiation,
                                    /*Complain=*/!Diagnoser.Suppressed);
        }
      }
    }
  
    if (Diagnoser.Suppressed)
      return true;
  
    // We have an incomplete type. Produce a diagnostic.
    if (Ident___float128 &&
        T == Context.getTypeDeclType(Context.getFloat128StubType())) {
      Diag(Loc, diag::err_typecheck_decl_incomplete_type___float128);
      return true;
    }
  
    Diagnoser.diagnose(*this, Loc, T);
  
    // If the type was a forward declaration of a class/struct/union
    // type, produce a note.
    if (Tag && !Tag->getDecl()->isInvalidDecl())
      Diag(Tag->getDecl()->getLocation(),
           Tag->isBeingDefined() ? diag::note_type_being_defined
                                 : diag::note_forward_declaration)
        << QualType(Tag, 0);
  
    // If the Objective-C class was a forward declaration, produce a note.
    if (IFace && !IFace->getDecl()->isInvalidDecl())
      Diag(IFace->getDecl()->getLocation(), diag::note_forward_class);
  
    // If we have external information that we can use to suggest a fix,
    // produce a note.
    if (ExternalSource)
      ExternalSource->MaybeDiagnoseMissingCompleteType(Loc, T);
  
    return true;
  }
  
  bool Sema::RequireCompleteType(SourceLocation Loc, QualType T,
                                 unsigned DiagID) {
    TypeDiagnoserDiag Diagnoser(DiagID);
    return RequireCompleteType(Loc, T, Diagnoser);
  }
  
  /// \brief Get diagnostic %select index for tag kind for
  /// literal type diagnostic message.
  /// WARNING: Indexes apply to particular diagnostics only!
  ///
  /// \returns diagnostic %select index.
  static unsigned getLiteralDiagFromTagKind(TagTypeKind Tag) {
    switch (Tag) {
    case TTK_Struct: return 0;
    case TTK_Interface: return 1;
    case TTK_Class:  return 2;
    default: llvm_unreachable("Invalid tag kind for literal type diagnostic!");
    }
  }
  
  /// @brief Ensure that the type T is a literal type.
  ///
  /// This routine checks whether the type @p T is a literal type. If @p T is an
  /// incomplete type, an attempt is made to complete it. If @p T is a literal
  /// type, or @p AllowIncompleteType is true and @p T is an incomplete type,
  /// returns false. Otherwise, this routine issues the diagnostic @p PD (giving
  /// it the type @p T), along with notes explaining why the type is not a
  /// literal type, and returns true.
  ///
  /// @param Loc  The location in the source that the non-literal type
  /// diagnostic should refer to.
  ///
  /// @param T  The type that this routine is examining for literalness.
  ///
  /// @param Diagnoser Emits a diagnostic if T is not a literal type.
  ///
  /// @returns @c true if @p T is not a literal type and a diagnostic was emitted,
  /// @c false otherwise.
  bool Sema::RequireLiteralType(SourceLocation Loc, QualType T,
                                TypeDiagnoser &Diagnoser) {
    assert(!T->isDependentType() && "type should not be dependent");
  
    QualType ElemType = Context.getBaseElementType(T);
    RequireCompleteType(Loc, ElemType, 0);
  
    if (T->isLiteralType(Context))
      return false;
  
    if (Diagnoser.Suppressed)
      return true;
  
    Diagnoser.diagnose(*this, Loc, T);
  
    if (T->isVariableArrayType())
      return true;
  
    const RecordType *RT = ElemType->getAs<RecordType>();
    if (!RT)
      return true;
  
    const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
  
    // A partially-defined class type can't be a literal type, because a literal
    // class type must have a trivial destructor (which can't be checked until
    // the class definition is complete).
    if (!RD->isCompleteDefinition()) {
      RequireCompleteType(Loc, ElemType, diag::note_non_literal_incomplete, T);
      return true;
    }
  
    // If the class has virtual base classes, then it's not an aggregate, and
    // cannot have any constexpr constructors or a trivial default constructor,
    // so is non-literal. This is better to diagnose than the resulting absence
    // of constexpr constructors.
    if (RD->getNumVBases()) {
      Diag(RD->getLocation(), diag::note_non_literal_virtual_base)
        << getLiteralDiagFromTagKind(RD->getTagKind()) << RD->getNumVBases();
      for (const auto &I : RD->vbases())
        Diag(I.getLocStart(), diag::note_constexpr_virtual_base_here)
            << I.getSourceRange();
    } else if (!RD->isAggregate() && !RD->hasConstexprNonCopyMoveConstructor() &&
               !RD->hasTrivialDefaultConstructor()) {
      Diag(RD->getLocation(), diag::note_non_literal_no_constexpr_ctors) << RD;
    } else if (RD->hasNonLiteralTypeFieldsOrBases()) {
      for (const auto &I : RD->bases()) {
        if (!I.getType()->isLiteralType(Context)) {
          Diag(I.getLocStart(),
               diag::note_non_literal_base_class)
            << RD << I.getType() << I.getSourceRange();
          return true;
        }
      }
      for (const auto *I : RD->fields()) {
        if (!I->getType()->isLiteralType(Context) ||
            I->getType().isVolatileQualified()) {
          Diag(I->getLocation(), diag::note_non_literal_field)
            << RD << I << I->getType()
            << I->getType().isVolatileQualified();
          return true;
        }
      }
    } else if (!RD->hasTrivialDestructor()) {
      // All fields and bases are of literal types, so have trivial destructors.
      // If this class's destructor is non-trivial it must be user-declared.
      CXXDestructorDecl *Dtor = RD->getDestructor();
      assert(Dtor && "class has literal fields and bases but no dtor?");
      if (!Dtor)
        return true;
  
      Diag(Dtor->getLocation(), Dtor->isUserProvided() ?
           diag::note_non_literal_user_provided_dtor :
           diag::note_non_literal_nontrivial_dtor) << RD;
      if (!Dtor->isUserProvided())
        SpecialMemberIsTrivial(Dtor, CXXDestructor, /*Diagnose*/true);
    }
  
    return true;
  }
  
  bool Sema::RequireLiteralType(SourceLocation Loc, QualType T, unsigned DiagID) {
    TypeDiagnoserDiag Diagnoser(DiagID);
    return RequireLiteralType(Loc, T, Diagnoser);
  }
  
  /// \brief Retrieve a version of the type 'T' that is elaborated by Keyword
  /// and qualified by the nested-name-specifier contained in SS.
  QualType Sema::getElaboratedType(ElaboratedTypeKeyword Keyword,
                                   const CXXScopeSpec &SS, QualType T) {
    if (T.isNull())
      return T;
    NestedNameSpecifier *NNS;
    if (SS.isValid())
      NNS = SS.getScopeRep();
    else {
      if (Keyword == ETK_None)
        return T;
      NNS = nullptr;
    }
    return Context.getElaboratedType(Keyword, NNS, T);
  }
  
  QualType Sema::BuildTypeofExprType(Expr *E, SourceLocation Loc) {
    ExprResult ER = CheckPlaceholderExpr(E);
    if (ER.isInvalid()) return QualType();
    E = ER.get();
  
    if (!E->isTypeDependent()) {
      QualType T = E->getType();
      if (const TagType *TT = T->getAs<TagType>())
        DiagnoseUseOfDecl(TT->getDecl(), E->getExprLoc());
    }
    return Context.getTypeOfExprType(E);
  }
  
  /// getDecltypeForExpr - Given an expr, will return the decltype for
  /// that expression, according to the rules in C++11
  /// [dcl.type.simple]p4 and C++11 [expr.lambda.prim]p18.
  static QualType getDecltypeForExpr(Sema &S, Expr *E) {
    if (E->isTypeDependent())
      return S.Context.DependentTy;
  
    // C++11 [dcl.type.simple]p4:
    //   The type denoted by decltype(e) is defined as follows:
    //
    //     - if e is an unparenthesized id-expression or an unparenthesized class
    //       member access (5.2.5), decltype(e) is the type of the entity named
    //       by e. If there is no such entity, or if e names a set of overloaded
    //       functions, the program is ill-formed;
    //
    // We apply the same rules for Objective-C ivar and property references.
    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
      if (const ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl()))
        return VD->getType();
    } else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
      if (const FieldDecl *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()))
        return FD->getType();
    } else if (const ObjCIvarRefExpr *IR = dyn_cast<ObjCIvarRefExpr>(E)) {
      return IR->getDecl()->getType();
    } else if (const ObjCPropertyRefExpr *PR = dyn_cast<ObjCPropertyRefExpr>(E)) {
      if (PR->isExplicitProperty())
        return PR->getExplicitProperty()->getType();
    }
    
    // C++11 [expr.lambda.prim]p18:
    //   Every occurrence of decltype((x)) where x is a possibly
    //   parenthesized id-expression that names an entity of automatic
    //   storage duration is treated as if x were transformed into an
    //   access to a corresponding data member of the closure type that
    //   would have been declared if x were an odr-use of the denoted
    //   entity.
    using namespace sema;
    if (S.getCurLambda()) {
      if (isa<ParenExpr>(E)) {
        if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
          if (VarDecl *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
            QualType T = S.getCapturedDeclRefType(Var, DRE->getLocation());
            if (!T.isNull())
              return S.Context.getLValueReferenceType(T);
          }
        }
      }
    }
  
  
    // C++11 [dcl.type.simple]p4:
    //   [...]
    QualType T = E->getType();
    switch (E->getValueKind()) {
    //     - otherwise, if e is an xvalue, decltype(e) is T&&, where T is the
    //       type of e;
    case VK_XValue: T = S.Context.getRValueReferenceType(T); break;
    //     - otherwise, if e is an lvalue, decltype(e) is T&, where T is the
    //       type of e;
    case VK_LValue: T = S.Context.getLValueReferenceType(T); break;
    //  - otherwise, decltype(e) is the type of e.
    case VK_RValue: break;
    }
  
    return T;
  }
  
  QualType Sema::BuildDecltypeType(Expr *E, SourceLocation Loc) {
    ExprResult ER = CheckPlaceholderExpr(E);
    if (ER.isInvalid()) return QualType();
    E = ER.get();
  
    return Context.getDecltypeType(E, getDecltypeForExpr(*this, E));
  }
  
  QualType Sema::BuildUnaryTransformType(QualType BaseType,
                                         UnaryTransformType::UTTKind UKind,
                                         SourceLocation Loc) {
    switch (UKind) {
    case UnaryTransformType::EnumUnderlyingType:
      if (!BaseType->isDependentType() && !BaseType->isEnumeralType()) {
        Diag(Loc, diag::err_only_enums_have_underlying_types);
        return QualType();
      } else {
        QualType Underlying = BaseType;
        if (!BaseType->isDependentType()) {
          // The enum could be incomplete if we're parsing its definition or
          // recovering from an error.
          NamedDecl *FwdDecl = nullptr;
          if (BaseType->isIncompleteType(&FwdDecl)) {
            Diag(Loc, diag::err_underlying_type_of_incomplete_enum) << BaseType;
            Diag(FwdDecl->getLocation(), diag::note_forward_declaration) << FwdDecl;
            return QualType();
          }
  
          EnumDecl *ED = BaseType->getAs<EnumType>()->getDecl();
          assert(ED && "EnumType has no EnumDecl");
  
          DiagnoseUseOfDecl(ED, Loc);
  
          Underlying = ED->getIntegerType();
          assert(!Underlying.isNull());
        }
        return Context.getUnaryTransformType(BaseType, Underlying,
                                          UnaryTransformType::EnumUnderlyingType);
      }
    }
    llvm_unreachable("unknown unary transform type");
  }
  
  QualType Sema::BuildAtomicType(QualType T, SourceLocation Loc) {
    if (!T->isDependentType()) {
      // FIXME: It isn't entirely clear whether incomplete atomic types
      // are allowed or not; for simplicity, ban them for the moment.
      if (RequireCompleteType(Loc, T, diag::err_atomic_specifier_bad_type, 0))
        return QualType();
  
      int DisallowedKind = -1;
      if (T->isArrayType())
        DisallowedKind = 1;
      else if (T->isFunctionType())
        DisallowedKind = 2;
      else if (T->isReferenceType())
        DisallowedKind = 3;
      else if (T->isAtomicType())
        DisallowedKind = 4;
      else if (T.hasQualifiers())
        DisallowedKind = 5;
      else if (!T.isTriviallyCopyableType(Context))
        // Some other non-trivially-copyable type (probably a C++ class)
        DisallowedKind = 6;
  
      if (DisallowedKind != -1) {
        Diag(Loc, diag::err_atomic_specifier_bad_type) << DisallowedKind << T;
        return QualType();
      }
  
      // FIXME: Do we need any handling for ARC here?
    }
  
    // Build the pointer type.
    return Context.getAtomicType(T);
  }
  