ParseDecl.cpp

//===--- ParseDecl.cpp - Declaration Parsing --------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file implements the Declaration portions of the Parser interfaces.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/PrettyDeclStackTrace.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/Basic/AttributeCommonInfo.h"
#include "clang/Basic/Attributes.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Parse/ParseDiagnostic.h"
#include "clang/Parse/Parser.h"
#include "clang/Parse/RAIIObjectsForParser.h"
#include "clang/Sema/EnterExpressionEvaluationContext.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringSwitch.h"
#include <optional>

using namespace clang;

//===----------------------------------------------------------------------===//
// C99 6.7: Declarations.
//===----------------------------------------------------------------------===//

/// ParseTypeName
///       type-name: [C99 6.7.6]
///         specifier-qualifier-list abstract-declarator[opt]
///
/// Called type-id in C++.
TypeResult Parser::ParseTypeName(SourceRange *Range, DeclaratorContext Context,
                                 AccessSpecifier AS, Decl **OwnedType,
                                 ParsedAttributes *Attrs) {
  DeclSpecContext DSC = getDeclSpecContextFromDeclaratorContext(Context);
  if (DSC == DeclSpecContext::DSC_normal)
    DSC = DeclSpecContext::DSC_type_specifier;

  // Parse the common declaration-specifiers piece.
  DeclSpec DS(AttrFactory);
  if (Attrs)
    DS.addAttributes(*Attrs);
  ParseSpecifierQualifierList(DS, AS, DSC);
  if (OwnedType)
    *OwnedType = DS.isTypeSpecOwned() ? DS.getRepAsDecl() : nullptr;

  // Move declspec attributes to ParsedAttributes
  if (Attrs) {
    llvm::SmallVector<ParsedAttr *, 1> ToBeMoved;
    for (ParsedAttr &AL : DS.getAttributes()) {
      if (AL.isDeclspecAttribute())
        ToBeMoved.push_back(&AL);
    }

    for (ParsedAttr *AL : ToBeMoved)
      Attrs->takeOneFrom(DS.getAttributes(), AL);
  }

  // Parse the abstract-declarator, if present.
  Declarator DeclaratorInfo(DS, ParsedAttributesView::none(), Context);
  ParseDeclarator(DeclaratorInfo);
  if (Range)
    *Range = DeclaratorInfo.getSourceRange();

  if (DeclaratorInfo.isInvalidType())
    return true;

  return Actions.ActOnTypeName(getCurScope(), DeclaratorInfo);
}

/// Normalizes an attribute name by dropping prefixed and suffixed __.
static StringRef normalizeAttrName(StringRef Name) {
  if (Name.size() >= 4 && Name.startswith("__") && Name.endswith("__"))
    return Name.drop_front(2).drop_back(2);
  return Name;
}

/// isAttributeLateParsed - Return true if the attribute has arguments that
/// require late parsing.
static bool isAttributeLateParsed(const IdentifierInfo &II) {
#define CLANG_ATTR_LATE_PARSED_LIST
    return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
        .Default(false);
#undef CLANG_ATTR_LATE_PARSED_LIST
}

/// Check if the a start and end source location expand to the same macro.
static bool FindLocsWithCommonFileID(Preprocessor &PP, SourceLocation StartLoc,
                                     SourceLocation EndLoc) {
  if (!StartLoc.isMacroID() || !EndLoc.isMacroID())
    return false;

  SourceManager &SM = PP.getSourceManager();
  if (SM.getFileID(StartLoc) != SM.getFileID(EndLoc))
    return false;

  bool AttrStartIsInMacro =
      Lexer::isAtStartOfMacroExpansion(StartLoc, SM, PP.getLangOpts());
  bool AttrEndIsInMacro =
      Lexer::isAtEndOfMacroExpansion(EndLoc, SM, PP.getLangOpts());
  return AttrStartIsInMacro && AttrEndIsInMacro;
}

void Parser::ParseAttributes(unsigned WhichAttrKinds, ParsedAttributes &Attrs,
                             LateParsedAttrList *LateAttrs) {
  bool MoreToParse;
  do {
    // Assume there's nothing left to parse, but if any attributes are in fact
    // parsed, loop to ensure all specified attribute combinations are parsed.
    MoreToParse = false;
    if (WhichAttrKinds & PAKM_CXX11)
      MoreToParse |= MaybeParseCXX11Attributes(Attrs);
    if (WhichAttrKinds & PAKM_GNU)
      MoreToParse |= MaybeParseGNUAttributes(Attrs, LateAttrs);
    if (WhichAttrKinds & PAKM_Declspec)
      MoreToParse |= MaybeParseMicrosoftDeclSpecs(Attrs);
  } while (MoreToParse);
}

/// ParseGNUAttributes - Parse a non-empty attributes list.
///
/// [GNU] attributes:
///         attribute
///         attributes attribute
///
/// [GNU]  attribute:
///          '__attribute__' '(' '(' attribute-list ')' ')'
///
/// [GNU]  attribute-list:
///          attrib
///          attribute_list ',' attrib
///
/// [GNU]  attrib:
///          empty
///          attrib-name
///          attrib-name '(' identifier ')'
///          attrib-name '(' identifier ',' nonempty-expr-list ')'
///          attrib-name '(' argument-expression-list [C99 6.5.2] ')'
///
/// [GNU]  attrib-name:
///          identifier
///          typespec
///          typequal
///          storageclass
///
/// Whether an attribute takes an 'identifier' is determined by the
/// attrib-name. GCC's behavior here is not worth imitating:
///
///  * In C mode, if the attribute argument list starts with an identifier
///    followed by a ',' or an ')', and the identifier doesn't resolve to
///    a type, it is parsed as an identifier. If the attribute actually
///    wanted an expression, it's out of luck (but it turns out that no
///    attributes work that way, because C constant expressions are very
///    limited).
///  * In C++ mode, if the attribute argument list starts with an identifier,
///    and the attribute *wants* an identifier, it is parsed as an identifier.
///    At block scope, any additional tokens between the identifier and the
///    ',' or ')' are ignored, otherwise they produce a parse error.
///
/// We follow the C++ model, but don't allow junk after the identifier.
void Parser::ParseGNUAttributes(ParsedAttributes &Attrs,
                                LateParsedAttrList *LateAttrs, Declarator *D) {
  assert(Tok.is(tok::kw___attribute) && "Not a GNU attribute list!");

  SourceLocation StartLoc = Tok.getLocation();
  SourceLocation EndLoc = StartLoc;

  while (Tok.is(tok::kw___attribute)) {
    SourceLocation AttrTokLoc = ConsumeToken();
    unsigned OldNumAttrs = Attrs.size();
    unsigned OldNumLateAttrs = LateAttrs ? LateAttrs->size() : 0;

    if (ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after,
                         "attribute")) {
      SkipUntil(tok::r_paren, StopAtSemi); // skip until ) or ;
      return;
    }
    if (ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after, "(")) {
      SkipUntil(tok::r_paren, StopAtSemi); // skip until ) or ;
      return;
    }
    // Parse the attribute-list. e.g. __attribute__(( weak, alias("__f") ))
    do {
      // Eat preceeding commas to allow __attribute__((,,,foo))
      while (TryConsumeToken(tok::comma))
        ;

      // Expect an identifier or declaration specifier (const, int, etc.)
      if (Tok.isAnnotation())
        break;
      if (Tok.is(tok::code_completion)) {
        cutOffParsing();
        Actions.CodeCompleteAttribute(AttributeCommonInfo::Syntax::AS_GNU);
        break;
      }
      IdentifierInfo *AttrName = Tok.getIdentifierInfo();
      if (!AttrName)
        break;

      SourceLocation AttrNameLoc = ConsumeToken();

      if (Tok.isNot(tok::l_paren)) {
        Attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                     ParsedAttr::Form::GNU());
        continue;
      }

      // Handle "parameterized" attributes
      if (!LateAttrs || !isAttributeLateParsed(*AttrName)) {
        ParseGNUAttributeArgs(AttrName, AttrNameLoc, Attrs, &EndLoc, nullptr,
                              SourceLocation(), ParsedAttr::Form::GNU(), D);
        continue;
      }

      // Handle attributes with arguments that require late parsing.
      LateParsedAttribute *LA =
          new LateParsedAttribute(this, *AttrName, AttrNameLoc);
      LateAttrs->push_back(LA);

      // Attributes in a class are parsed at the end of the class, along
      // with other late-parsed declarations.
      if (!ClassStack.empty() && !LateAttrs->parseSoon())
        getCurrentClass().LateParsedDeclarations.push_back(LA);

      // Be sure ConsumeAndStoreUntil doesn't see the start l_paren, since it
      // recursively consumes balanced parens.
      LA->Toks.push_back(Tok);
      ConsumeParen();
      // Consume everything up to and including the matching right parens.
      ConsumeAndStoreUntil(tok::r_paren, LA->Toks, /*StopAtSemi=*/true);

      Token Eof;
      Eof.startToken();
      Eof.setLocation(Tok.getLocation());
      LA->Toks.push_back(Eof);
    } while (Tok.is(tok::comma));

    if (ExpectAndConsume(tok::r_paren))
      SkipUntil(tok::r_paren, StopAtSemi);
    SourceLocation Loc = Tok.getLocation();
    if (ExpectAndConsume(tok::r_paren))
      SkipUntil(tok::r_paren, StopAtSemi);
    EndLoc = Loc;

    // If this was declared in a macro, attach the macro IdentifierInfo to the
    // parsed attribute.
    auto &SM = PP.getSourceManager();
    if (!SM.isWrittenInBuiltinFile(SM.getSpellingLoc(AttrTokLoc)) &&
        FindLocsWithCommonFileID(PP, AttrTokLoc, Loc)) {
      CharSourceRange ExpansionRange = SM.getExpansionRange(AttrTokLoc);
      StringRef FoundName =
          Lexer::getSourceText(ExpansionRange, SM, PP.getLangOpts());
      IdentifierInfo *MacroII = PP.getIdentifierInfo(FoundName);

      for (unsigned i = OldNumAttrs; i < Attrs.size(); ++i)
        Attrs[i].setMacroIdentifier(MacroII, ExpansionRange.getBegin());

      if (LateAttrs) {
        for (unsigned i = OldNumLateAttrs; i < LateAttrs->size(); ++i)
          (*LateAttrs)[i]->MacroII = MacroII;
      }
    }
  }

  Attrs.Range = SourceRange(StartLoc, EndLoc);
}

/// Determine whether the given attribute has an identifier argument.
static bool attributeHasIdentifierArg(const IdentifierInfo &II) {
#define CLANG_ATTR_IDENTIFIER_ARG_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
           .Default(false);
#undef CLANG_ATTR_IDENTIFIER_ARG_LIST
}

/// Determine whether the given attribute has a variadic identifier argument.
static bool attributeHasVariadicIdentifierArg(const IdentifierInfo &II) {
#define CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
           .Default(false);
#undef CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
}

/// Determine whether the given attribute treats kw_this as an identifier.
static bool attributeTreatsKeywordThisAsIdentifier(const IdentifierInfo &II) {
#define CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
           .Default(false);
#undef CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST
}

/// Determine if an attribute accepts parameter packs.
static bool attributeAcceptsExprPack(const IdentifierInfo &II) {
#define CLANG_ATTR_ACCEPTS_EXPR_PACK
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
      .Default(false);
#undef CLANG_ATTR_ACCEPTS_EXPR_PACK
}

/// Determine whether the given attribute parses a type argument.
static bool attributeIsTypeArgAttr(const IdentifierInfo &II) {
#define CLANG_ATTR_TYPE_ARG_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
           .Default(false);
#undef CLANG_ATTR_TYPE_ARG_LIST
}

/// Determine whether the given attribute requires parsing its arguments
/// in an unevaluated context or not.
static bool attributeParsedArgsUnevaluated(const IdentifierInfo &II) {
#define CLANG_ATTR_ARG_CONTEXT_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
           .Default(false);
#undef CLANG_ATTR_ARG_CONTEXT_LIST
}

IdentifierLoc *Parser::ParseIdentifierLoc() {
  assert(Tok.is(tok::identifier) && "expected an identifier");
  IdentifierLoc *IL = IdentifierLoc::create(Actions.Context,
                                            Tok.getLocation(),
                                            Tok.getIdentifierInfo());
  ConsumeToken();
  return IL;
}

void Parser::ParseAttributeWithTypeArg(IdentifierInfo &AttrName,
                                       SourceLocation AttrNameLoc,
                                       ParsedAttributes &Attrs,
                                       IdentifierInfo *ScopeName,
                                       SourceLocation ScopeLoc,
                                       ParsedAttr::Form Form) {
  BalancedDelimiterTracker Parens(*this, tok::l_paren);
  Parens.consumeOpen();

  TypeResult T;
  if (Tok.isNot(tok::r_paren))
    T = ParseTypeName();

  if (Parens.consumeClose())
    return;

  if (T.isInvalid())
    return;

  if (T.isUsable())
    Attrs.addNewTypeAttr(&AttrName,
                         SourceRange(AttrNameLoc, Parens.getCloseLocation()),
                         ScopeName, ScopeLoc, T.get(), Form);
  else
    Attrs.addNew(&AttrName, SourceRange(AttrNameLoc, Parens.getCloseLocation()),
                 ScopeName, ScopeLoc, nullptr, 0, Form);
}

unsigned Parser::ParseAttributeArgsCommon(
    IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  // Ignore the left paren location for now.
  ConsumeParen();

  bool ChangeKWThisToIdent = attributeTreatsKeywordThisAsIdentifier(*AttrName);
  bool AttributeIsTypeArgAttr = attributeIsTypeArgAttr(*AttrName);
  bool AttributeHasVariadicIdentifierArg =
      attributeHasVariadicIdentifierArg(*AttrName);

  // Interpret "kw_this" as an identifier if the attributed requests it.
  if (ChangeKWThisToIdent && Tok.is(tok::kw_this))
    Tok.setKind(tok::identifier);

  ArgsVector ArgExprs;
  if (Tok.is(tok::identifier)) {
    // If this attribute wants an 'identifier' argument, make it so.
    bool IsIdentifierArg = AttributeHasVariadicIdentifierArg ||
                           attributeHasIdentifierArg(*AttrName);
    ParsedAttr::Kind AttrKind =
        ParsedAttr::getParsedKind(AttrName, ScopeName, Form.getSyntax());

    // If we don't know how to parse this attribute, but this is the only
    // token in this argument, assume it's meant to be an identifier.
    if (AttrKind == ParsedAttr::UnknownAttribute ||
        AttrKind == ParsedAttr::IgnoredAttribute) {
      const Token &Next = NextToken();
      IsIdentifierArg = Next.isOneOf(tok::r_paren, tok::comma);
    }

    if (IsIdentifierArg)
      ArgExprs.push_back(ParseIdentifierLoc());
  }

  ParsedType TheParsedType;
  if (!ArgExprs.empty() ? Tok.is(tok::comma) : Tok.isNot(tok::r_paren)) {
    // Eat the comma.
    if (!ArgExprs.empty())
      ConsumeToken();

    if (AttributeIsTypeArgAttr) {
      // FIXME: Multiple type arguments are not implemented.
      TypeResult T = ParseTypeName();
      if (T.isInvalid()) {
        SkipUntil(tok::r_paren, StopAtSemi);
        return 0;
      }
      if (T.isUsable())
        TheParsedType = T.get();
    } else if (AttributeHasVariadicIdentifierArg) {
      // Parse variadic identifier arg. This can either consume identifiers or
      // expressions. Variadic identifier args do not support parameter packs
      // because those are typically used for attributes with enumeration
      // arguments, and those enumerations are not something the user could
      // express via a pack.
      do {
        // Interpret "kw_this" as an identifier if the attributed requests it.
        if (ChangeKWThisToIdent && Tok.is(tok::kw_this))
          Tok.setKind(tok::identifier);

        ExprResult ArgExpr;
        if (Tok.is(tok::identifier)) {
          ArgExprs.push_back(ParseIdentifierLoc());
        } else {
          bool Uneval = attributeParsedArgsUnevaluated(*AttrName);
          EnterExpressionEvaluationContext Unevaluated(
              Actions,
              Uneval ? Sema::ExpressionEvaluationContext::Unevaluated
                     : Sema::ExpressionEvaluationContext::ConstantEvaluated);

          ExprResult ArgExpr(
              Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression()));

          if (ArgExpr.isInvalid()) {
            SkipUntil(tok::r_paren, StopAtSemi);
            return 0;
          }
          ArgExprs.push_back(ArgExpr.get());
        }
        // Eat the comma, move to the next argument
      } while (TryConsumeToken(tok::comma));
    } else {
      // General case. Parse all available expressions.
      bool Uneval = attributeParsedArgsUnevaluated(*AttrName);
      EnterExpressionEvaluationContext Unevaluated(
          Actions, Uneval
                       ? Sema::ExpressionEvaluationContext::Unevaluated
                       : Sema::ExpressionEvaluationContext::ConstantEvaluated);

      ExprVector ParsedExprs;
      if (ParseExpressionList(ParsedExprs, llvm::function_ref<void()>(),
                              /*FailImmediatelyOnInvalidExpr=*/true,
                              /*EarlyTypoCorrection=*/true)) {
        SkipUntil(tok::r_paren, StopAtSemi);
        return 0;
      }

      // Pack expansion must currently be explicitly supported by an attribute.
      for (size_t I = 0; I < ParsedExprs.size(); ++I) {
        if (!isa<PackExpansionExpr>(ParsedExprs[I]))
          continue;

        if (!attributeAcceptsExprPack(*AttrName)) {
          Diag(Tok.getLocation(),
               diag::err_attribute_argument_parm_pack_not_supported)
              << AttrName;
          SkipUntil(tok::r_paren, StopAtSemi);
          return 0;
        }
      }

      ArgExprs.insert(ArgExprs.end(), ParsedExprs.begin(), ParsedExprs.end());
    }
  }

  SourceLocation RParen = Tok.getLocation();
  if (!ExpectAndConsume(tok::r_paren)) {
    SourceLocation AttrLoc = ScopeLoc.isValid() ? ScopeLoc : AttrNameLoc;

    if (AttributeIsTypeArgAttr && !TheParsedType.get().isNull()) {
      Attrs.addNewTypeAttr(AttrName, SourceRange(AttrNameLoc, RParen),
                           ScopeName, ScopeLoc, TheParsedType, Form);
    } else {
      Attrs.addNew(AttrName, SourceRange(AttrLoc, RParen), ScopeName, ScopeLoc,
                   ArgExprs.data(), ArgExprs.size(), Form);
    }
  }

  if (EndLoc)
    *EndLoc = RParen;

  return static_cast<unsigned>(ArgExprs.size() + !TheParsedType.get().isNull());
}

/// Parse the arguments to a parameterized GNU attribute or
/// a C++11 attribute in "gnu" namespace.
void Parser::ParseGNUAttributeArgs(
    IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form, Declarator *D) {

  assert(Tok.is(tok::l_paren) && "Attribute arg list not starting with '('");

  ParsedAttr::Kind AttrKind =
      ParsedAttr::getParsedKind(AttrName, ScopeName, Form.getSyntax());

  if (AttrKind == ParsedAttr::AT_Availability) {
    ParseAvailabilityAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                               ScopeLoc, Form);
    return;
  } else if (AttrKind == ParsedAttr::AT_ExternalSourceSymbol) {
    ParseExternalSourceSymbolAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                       ScopeName, ScopeLoc, Form);
    return;
  } else if (AttrKind == ParsedAttr::AT_ObjCBridgeRelated) {
    ParseObjCBridgeRelatedAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                    ScopeName, ScopeLoc, Form);
    return;
  } else if (AttrKind == ParsedAttr::AT_SwiftNewType) {
    ParseSwiftNewTypeAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                               ScopeLoc, Form);
    return;
  } else if (AttrKind == ParsedAttr::AT_TypeTagForDatatype) {
    ParseTypeTagForDatatypeAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                     ScopeName, ScopeLoc, Form);
    return;
  } else if (attributeIsTypeArgAttr(*AttrName)) {
    ParseAttributeWithTypeArg(*AttrName, AttrNameLoc, Attrs, ScopeName,
                              ScopeLoc, Form);
    return;
  }

  // These may refer to the function arguments, but need to be parsed early to
  // participate in determining whether it's a redeclaration.
  std::optional<ParseScope> PrototypeScope;
  if (normalizeAttrName(AttrName->getName()) == "enable_if" &&
      D && D->isFunctionDeclarator()) {
    DeclaratorChunk::FunctionTypeInfo FTI = D->getFunctionTypeInfo();
    PrototypeScope.emplace(this, Scope::FunctionPrototypeScope |
                                     Scope::FunctionDeclarationScope |
                                     Scope::DeclScope);
    for (unsigned i = 0; i != FTI.NumParams; ++i) {
      ParmVarDecl *Param = cast<ParmVarDecl>(FTI.Params[i].Param);
      Actions.ActOnReenterCXXMethodParameter(getCurScope(), Param);
    }
  }

  ParseAttributeArgsCommon(AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                           ScopeLoc, Form);
}

unsigned Parser::ParseClangAttributeArgs(
    IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  assert(Tok.is(tok::l_paren) && "Attribute arg list not starting with '('");

  ParsedAttr::Kind AttrKind =
      ParsedAttr::getParsedKind(AttrName, ScopeName, Form.getSyntax());

  switch (AttrKind) {
  default:
    return ParseAttributeArgsCommon(AttrName, AttrNameLoc, Attrs, EndLoc,
                                    ScopeName, ScopeLoc, Form);
  case ParsedAttr::AT_ExternalSourceSymbol:
    ParseExternalSourceSymbolAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                       ScopeName, ScopeLoc, Form);
    break;
  case ParsedAttr::AT_Availability:
    ParseAvailabilityAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                               ScopeLoc, Form);
    break;
  case ParsedAttr::AT_ObjCBridgeRelated:
    ParseObjCBridgeRelatedAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                    ScopeName, ScopeLoc, Form);
    break;
  case ParsedAttr::AT_SwiftNewType:
    ParseSwiftNewTypeAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                               ScopeLoc, Form);
    break;
  case ParsedAttr::AT_TypeTagForDatatype:
    ParseTypeTagForDatatypeAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                     ScopeName, ScopeLoc, Form);
    break;
  }
  return !Attrs.empty() ? Attrs.begin()->getNumArgs() : 0;
}

bool Parser::ParseMicrosoftDeclSpecArgs(IdentifierInfo *AttrName,
                                        SourceLocation AttrNameLoc,
                                        ParsedAttributes &Attrs) {
  unsigned ExistingAttrs = Attrs.size();

  // If the attribute isn't known, we will not attempt to parse any
  // arguments.
  if (!hasAttribute(AttributeCommonInfo::Syntax::AS_Declspec, nullptr, AttrName,
                    getTargetInfo(), getLangOpts())) {
    // Eat the left paren, then skip to the ending right paren.
    ConsumeParen();
    SkipUntil(tok::r_paren);
    return false;
  }

  SourceLocation OpenParenLoc = Tok.getLocation();

  if (AttrName->getName() == "property") {
    // The property declspec is more complex in that it can take one or two
    // assignment expressions as a parameter, but the lhs of the assignment
    // must be named get or put.

    BalancedDelimiterTracker T(*this, tok::l_paren);
    T.expectAndConsume(diag::err_expected_lparen_after,
                       AttrName->getNameStart(), tok::r_paren);

    enum AccessorKind {
      AK_Invalid = -1,
      AK_Put = 0,
      AK_Get = 1 // indices into AccessorNames
    };
    IdentifierInfo *AccessorNames[] = {nullptr, nullptr};
    bool HasInvalidAccessor = false;

    // Parse the accessor specifications.
    while (true) {
      // Stop if this doesn't look like an accessor spec.
      if (!Tok.is(tok::identifier)) {
        // If the user wrote a completely empty list, use a special diagnostic.
        if (Tok.is(tok::r_paren) && !HasInvalidAccessor &&
            AccessorNames[AK_Put] == nullptr &&
            AccessorNames[AK_Get] == nullptr) {
          Diag(AttrNameLoc, diag::err_ms_property_no_getter_or_putter);
          break;
        }

        Diag(Tok.getLocation(), diag::err_ms_property_unknown_accessor);
        break;
      }

      AccessorKind Kind;
      SourceLocation KindLoc = Tok.getLocation();
      StringRef KindStr = Tok.getIdentifierInfo()->getName();
      if (KindStr == "get") {
        Kind = AK_Get;
      } else if (KindStr == "put") {
        Kind = AK_Put;

        // Recover from the common mistake of using 'set' instead of 'put'.
      } else if (KindStr == "set") {
        Diag(KindLoc, diag::err_ms_property_has_set_accessor)
            << FixItHint::CreateReplacement(KindLoc, "put");
        Kind = AK_Put;

        // Handle the mistake of forgetting the accessor kind by skipping
        // this accessor.
      } else if (NextToken().is(tok::comma) || NextToken().is(tok::r_paren)) {
        Diag(KindLoc, diag::err_ms_property_missing_accessor_kind);
        ConsumeToken();
        HasInvalidAccessor = true;
        goto next_property_accessor;

        // Otherwise, complain about the unknown accessor kind.
      } else {
        Diag(KindLoc, diag::err_ms_property_unknown_accessor);
        HasInvalidAccessor = true;
        Kind = AK_Invalid;

        // Try to keep parsing unless it doesn't look like an accessor spec.
        if (!NextToken().is(tok::equal))
          break;
      }

      // Consume the identifier.
      ConsumeToken();

      // Consume the '='.
      if (!TryConsumeToken(tok::equal)) {
        Diag(Tok.getLocation(), diag::err_ms_property_expected_equal)
            << KindStr;
        break;
      }

      // Expect the method name.
      if (!Tok.is(tok::identifier)) {
        Diag(Tok.getLocation(), diag::err_ms_property_expected_accessor_name);
        break;
      }

      if (Kind == AK_Invalid) {
        // Just drop invalid accessors.
      } else if (AccessorNames[Kind] != nullptr) {
        // Complain about the repeated accessor, ignore it, and keep parsing.
        Diag(KindLoc, diag::err_ms_property_duplicate_accessor) << KindStr;
      } else {
        AccessorNames[Kind] = Tok.getIdentifierInfo();
      }
      ConsumeToken();

    next_property_accessor:
      // Keep processing accessors until we run out.
      if (TryConsumeToken(tok::comma))
        continue;

      // If we run into the ')', stop without consuming it.
      if (Tok.is(tok::r_paren))
        break;

      Diag(Tok.getLocation(), diag::err_ms_property_expected_comma_or_rparen);
      break;
    }

    // Only add the property attribute if it was well-formed.
    if (!HasInvalidAccessor)
      Attrs.addNewPropertyAttr(AttrName, AttrNameLoc, nullptr, SourceLocation(),
                               AccessorNames[AK_Get], AccessorNames[AK_Put],
                               ParsedAttr::Form::Declspec());
    T.skipToEnd();
    return !HasInvalidAccessor;
  }

  unsigned NumArgs =
      ParseAttributeArgsCommon(AttrName, AttrNameLoc, Attrs, nullptr, nullptr,
                               SourceLocation(), ParsedAttr::Form::Declspec());

  // If this attribute's args were parsed, and it was expected to have
  // arguments but none were provided, emit a diagnostic.
  if (ExistingAttrs < Attrs.size() && Attrs.back().getMaxArgs() && !NumArgs) {
    Diag(OpenParenLoc, diag::err_attribute_requires_arguments) << AttrName;
    return false;
  }
  return true;
}

/// [MS] decl-specifier:
///             __declspec ( extended-decl-modifier-seq )
///
/// [MS] extended-decl-modifier-seq:
///             extended-decl-modifier[opt]
///             extended-decl-modifier extended-decl-modifier-seq
void Parser::ParseMicrosoftDeclSpecs(ParsedAttributes &Attrs) {
  assert(getLangOpts().DeclSpecKeyword && "__declspec keyword is not enabled");
  assert(Tok.is(tok::kw___declspec) && "Not a declspec!");

  SourceLocation StartLoc = Tok.getLocation();
  SourceLocation EndLoc = StartLoc;

  while (Tok.is(tok::kw___declspec)) {
    ConsumeToken();
    BalancedDelimiterTracker T(*this, tok::l_paren);
    if (T.expectAndConsume(diag::err_expected_lparen_after, "__declspec",
                           tok::r_paren))
      return;

    // An empty declspec is perfectly legal and should not warn.  Additionally,
    // you can specify multiple attributes per declspec.
    while (Tok.isNot(tok::r_paren)) {
      // Attribute not present.
      if (TryConsumeToken(tok::comma))
        continue;

      if (Tok.is(tok::code_completion)) {
        cutOffParsing();
        Actions.CodeCompleteAttribute(AttributeCommonInfo::AS_Declspec);
        return;
      }

      // We expect either a well-known identifier or a generic string.  Anything
      // else is a malformed declspec.
      bool IsString = Tok.getKind() == tok::string_literal;
      if (!IsString && Tok.getKind() != tok::identifier &&
          Tok.getKind() != tok::kw_restrict) {
        Diag(Tok, diag::err_ms_declspec_type);
        T.skipToEnd();
        return;
      }

      IdentifierInfo *AttrName;
      SourceLocation AttrNameLoc;
      if (IsString) {
        SmallString<8> StrBuffer;
        bool Invalid = false;
        StringRef Str = PP.getSpelling(Tok, StrBuffer, &Invalid);
        if (Invalid) {
          T.skipToEnd();
          return;
        }
        AttrName = PP.getIdentifierInfo(Str);
        AttrNameLoc = ConsumeStringToken();
      } else {
        AttrName = Tok.getIdentifierInfo();
        AttrNameLoc = ConsumeToken();
      }

      bool AttrHandled = false;

      // Parse attribute arguments.
      if (Tok.is(tok::l_paren))
        AttrHandled = ParseMicrosoftDeclSpecArgs(AttrName, AttrNameLoc, Attrs);
      else if (AttrName->getName() == "property")
        // The property attribute must have an argument list.
        Diag(Tok.getLocation(), diag::err_expected_lparen_after)
            << AttrName->getName();

      if (!AttrHandled)
        Attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                     ParsedAttr::Form::Declspec());
    }
    T.consumeClose();
    EndLoc = T.getCloseLocation();
  }

  Attrs.Range = SourceRange(StartLoc, EndLoc);
}

void Parser::ParseMicrosoftTypeAttributes(ParsedAttributes &attrs) {
  // Treat these like attributes
  while (true) {
    auto Kind = Tok.getKind();
    switch (Kind) {
    case tok::kw___fastcall:
    case tok::kw___stdcall:
    case tok::kw___thiscall:
    case tok::kw___regcall:
    case tok::kw___cdecl:
    case tok::kw___vectorcall:
    case tok::kw___ptr64:
    case tok::kw___w64:
    case tok::kw___ptr32:
    case tok::kw___sptr:
    case tok::kw___uptr: {
      IdentifierInfo *AttrName = Tok.getIdentifierInfo();
      SourceLocation AttrNameLoc = ConsumeToken();
      attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                   Kind);
      break;
    }
    default:
      return;
    }
  }
}

void Parser::ParseWebAssemblyFuncrefTypeAttribute(ParsedAttributes &attrs) {
  assert(Tok.is(tok::kw___funcref));
  SourceLocation StartLoc = Tok.getLocation();
  if (!getTargetInfo().getTriple().isWasm()) {
    ConsumeToken();
    Diag(StartLoc, diag::err_wasm_funcref_not_wasm);
    return;
  }

  IdentifierInfo *AttrName = Tok.getIdentifierInfo();
  SourceLocation AttrNameLoc = ConsumeToken();
  attrs.addNew(AttrName, AttrNameLoc, /*ScopeName=*/nullptr,
               /*ScopeLoc=*/SourceLocation{}, /*Args=*/nullptr, /*numArgs=*/0,
               tok::kw___funcref);
}

void Parser::DiagnoseAndSkipExtendedMicrosoftTypeAttributes() {
  SourceLocation StartLoc = Tok.getLocation();
  SourceLocation EndLoc = SkipExtendedMicrosoftTypeAttributes();

  if (EndLoc.isValid()) {
    SourceRange Range(StartLoc, EndLoc);
    Diag(StartLoc, diag::warn_microsoft_qualifiers_ignored) << Range;
  }
}

SourceLocation Parser::SkipExtendedMicrosoftTypeAttributes() {
  SourceLocation EndLoc;

  while (true) {
    switch (Tok.getKind()) {
    case tok::kw_const:
    case tok::kw_volatile:
    case tok::kw___fastcall:
    case tok::kw___stdcall:
    case tok::kw___thiscall:
    case tok::kw___cdecl:
    case tok::kw___vectorcall:
    case tok::kw___ptr32:
    case tok::kw___ptr64:
    case tok::kw___w64:
    case tok::kw___unaligned:
    case tok::kw___sptr:
    case tok::kw___uptr:
      EndLoc = ConsumeToken();
      break;
    default:
      return EndLoc;
    }
  }
}

void Parser::ParseBorlandTypeAttributes(ParsedAttributes &attrs) {
  // Treat these like attributes
  while (Tok.is(tok::kw___pascal)) {
    IdentifierInfo *AttrName = Tok.getIdentifierInfo();
    SourceLocation AttrNameLoc = ConsumeToken();
    attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                 tok::kw___pascal);
  }
}

void Parser::ParseOpenCLKernelAttributes(ParsedAttributes &attrs) {
  // Treat these like attributes
  while (Tok.is(tok::kw___kernel)) {
    IdentifierInfo *AttrName = Tok.getIdentifierInfo();
    SourceLocation AttrNameLoc = ConsumeToken();
    attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                 tok::kw___kernel);
  }
}

void Parser::ParseCUDAFunctionAttributes(ParsedAttributes &attrs) {
  while (Tok.is(tok::kw___noinline__)) {
    IdentifierInfo *AttrName = Tok.getIdentifierInfo();
    SourceLocation AttrNameLoc = ConsumeToken();
    attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                 tok::kw___noinline__);
  }
}

void Parser::ParseOpenCLQualifiers(ParsedAttributes &Attrs) {
  IdentifierInfo *AttrName = Tok.getIdentifierInfo();
  SourceLocation AttrNameLoc = Tok.getLocation();
  Attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
               Tok.getKind());
}

bool Parser::isHLSLQualifier(const Token &Tok) const {
  return Tok.is(tok::kw_groupshared);
}

void Parser::ParseHLSLQualifiers(ParsedAttributes &Attrs) {
  IdentifierInfo *AttrName = Tok.getIdentifierInfo();
  auto Kind = Tok.getKind();
  SourceLocation AttrNameLoc = ConsumeToken();
  Attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0, Kind);
}

void Parser::ParseNullabilityTypeSpecifiers(ParsedAttributes &attrs) {
  // Treat these like attributes, even though they're type specifiers.
  while (true) {
    auto Kind = Tok.getKind();
    switch (Kind) {
    case tok::kw__Nonnull:
    case tok::kw__Nullable:
    case tok::kw__Nullable_result:
    case tok::kw__Null_unspecified: {
      IdentifierInfo *AttrName = Tok.getIdentifierInfo();
      SourceLocation AttrNameLoc = ConsumeToken();
      if (!getLangOpts().ObjC)
        Diag(AttrNameLoc, diag::ext_nullability)
          << AttrName;
      attrs.addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc, nullptr, 0,
                   Kind);
      break;
    }
    default:
      return;
    }
  }
}

static bool VersionNumberSeparator(const char Separator) {
  return (Separator == '.' || Separator == '_');
}

/// Parse a version number.
///
/// version:
///   simple-integer
///   simple-integer '.' simple-integer
///   simple-integer '_' simple-integer
///   simple-integer '.' simple-integer '.' simple-integer
///   simple-integer '_' simple-integer '_' simple-integer
VersionTuple Parser::ParseVersionTuple(SourceRange &Range) {
  Range = SourceRange(Tok.getLocation(), Tok.getEndLoc());

  if (!Tok.is(tok::numeric_constant)) {
    Diag(Tok, diag::err_expected_version);
    SkipUntil(tok::comma, tok::r_paren,
              StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
    return VersionTuple();
  }

  // Parse the major (and possibly minor and subminor) versions, which
  // are stored in the numeric constant. We utilize a quirk of the
  // lexer, which is that it handles something like 1.2.3 as a single
  // numeric constant, rather than two separate tokens.
  SmallString<512> Buffer;
  Buffer.resize(Tok.getLength()+1);
  const char *ThisTokBegin = &Buffer[0];

  // Get the spelling of the token, which eliminates trigraphs, etc.
  bool Invalid = false;
  unsigned ActualLength = PP.getSpelling(Tok, ThisTokBegin, &Invalid);
  if (Invalid)
    return VersionTuple();

  // Parse the major version.
  unsigned AfterMajor = 0;
  unsigned Major = 0;
  while (AfterMajor < ActualLength && isDigit(ThisTokBegin[AfterMajor])) {
    Major = Major * 10 + ThisTokBegin[AfterMajor] - '0';
    ++AfterMajor;
  }

  if (AfterMajor == 0) {
    Diag(Tok, diag::err_expected_version);
    SkipUntil(tok::comma, tok::r_paren,
              StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
    return VersionTuple();
  }

  if (AfterMajor == ActualLength) {
    ConsumeToken();

    // We only had a single version component.
    if (Major == 0) {
      Diag(Tok, diag::err_zero_version);
      return VersionTuple();
    }

    return VersionTuple(Major);
  }

  const char AfterMajorSeparator = ThisTokBegin[AfterMajor];
  if (!VersionNumberSeparator(AfterMajorSeparator)
      || (AfterMajor + 1 == ActualLength)) {
    Diag(Tok, diag::err_expected_version);
    SkipUntil(tok::comma, tok::r_paren,
              StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
    return VersionTuple();
  }

  // Parse the minor version.
  unsigned AfterMinor = AfterMajor + 1;
  unsigned Minor = 0;
  while (AfterMinor < ActualLength && isDigit(ThisTokBegin[AfterMinor])) {
    Minor = Minor * 10 + ThisTokBegin[AfterMinor] - '0';
    ++AfterMinor;
  }

  if (AfterMinor == ActualLength) {
    ConsumeToken();

    // We had major.minor.
    if (Major == 0 && Minor == 0) {
      Diag(Tok, diag::err_zero_version);
      return VersionTuple();
    }

    return VersionTuple(Major, Minor);
  }

  const char AfterMinorSeparator = ThisTokBegin[AfterMinor];
  // If what follows is not a '.' or '_', we have a problem.
  if (!VersionNumberSeparator(AfterMinorSeparator)) {
    Diag(Tok, diag::err_expected_version);
    SkipUntil(tok::comma, tok::r_paren,
              StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
    return VersionTuple();
  }

  // Warn if separators, be it '.' or '_', do not match.
  if (AfterMajorSeparator != AfterMinorSeparator)
    Diag(Tok, diag::warn_expected_consistent_version_separator);

  // Parse the subminor version.
  unsigned AfterSubminor = AfterMinor + 1;
  unsigned Subminor = 0;
  while (AfterSubminor < ActualLength && isDigit(ThisTokBegin[AfterSubminor])) {
    Subminor = Subminor * 10 + ThisTokBegin[AfterSubminor] - '0';
    ++AfterSubminor;
  }

  if (AfterSubminor != ActualLength) {
    Diag(Tok, diag::err_expected_version);
    SkipUntil(tok::comma, tok::r_paren,
              StopAtSemi | StopBeforeMatch | StopAtCodeCompletion);
    return VersionTuple();
  }
  ConsumeToken();
  return VersionTuple(Major, Minor, Subminor);
}

/// Parse the contents of the "availability" attribute.
///
/// availability-attribute:
///   'availability' '(' platform ',' opt-strict version-arg-list,
///                      opt-replacement, opt-message')'
///
/// platform:
///   identifier
///
/// opt-strict:
///   'strict' ','
///
/// version-arg-list:
///   version-arg
///   version-arg ',' version-arg-list
///
/// version-arg:
///   'introduced' '=' version
///   'deprecated' '=' version
///   'obsoleted' = version
///   'unavailable'
/// opt-replacement:
///   'replacement' '=' <string>
/// opt-message:
///   'message' '=' <string>
void Parser::ParseAvailabilityAttribute(
    IdentifierInfo &Availability, SourceLocation AvailabilityLoc,
    ParsedAttributes &attrs, SourceLocation *endLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  enum { Introduced, Deprecated, Obsoleted, Unknown };
  AvailabilityChange Changes[Unknown];
  ExprResult MessageExpr, ReplacementExpr;

  // Opening '('.
  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.consumeOpen()) {
    Diag(Tok, diag::err_expected) << tok::l_paren;
    return;
  }

  // Parse the platform name.
  if (Tok.isNot(tok::identifier)) {
    Diag(Tok, diag::err_availability_expected_platform);
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }
  IdentifierLoc *Platform = ParseIdentifierLoc();
  if (const IdentifierInfo *const Ident = Platform->Ident) {
    // Canonicalize platform name from "macosx" to "macos".
    if (Ident->getName() == "macosx")
      Platform->Ident = PP.getIdentifierInfo("macos");
    // Canonicalize platform name from "macosx_app_extension" to
    // "macos_app_extension".
    else if (Ident->getName() == "macosx_app_extension")
      Platform->Ident = PP.getIdentifierInfo("macos_app_extension");
    else
      Platform->Ident = PP.getIdentifierInfo(
          AvailabilityAttr::canonicalizePlatformName(Ident->getName()));
  }

  // Parse the ',' following the platform name.
  if (ExpectAndConsume(tok::comma)) {
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }

  // If we haven't grabbed the pointers for the identifiers
  // "introduced", "deprecated", and "obsoleted", do so now.
  if (!Ident_introduced) {
    Ident_introduced = PP.getIdentifierInfo("introduced");
    Ident_deprecated = PP.getIdentifierInfo("deprecated");
    Ident_obsoleted = PP.getIdentifierInfo("obsoleted");
    Ident_unavailable = PP.getIdentifierInfo("unavailable");
    Ident_message = PP.getIdentifierInfo("message");
    Ident_strict = PP.getIdentifierInfo("strict");
    Ident_replacement = PP.getIdentifierInfo("replacement");
  }

  // Parse the optional "strict", the optional "replacement" and the set of
  // introductions/deprecations/removals.
  SourceLocation UnavailableLoc, StrictLoc;
  do {
    if (Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_availability_expected_change);
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }
    IdentifierInfo *Keyword = Tok.getIdentifierInfo();
    SourceLocation KeywordLoc = ConsumeToken();

    if (Keyword == Ident_strict) {
      if (StrictLoc.isValid()) {
        Diag(KeywordLoc, diag::err_availability_redundant)
          << Keyword << SourceRange(StrictLoc);
      }
      StrictLoc = KeywordLoc;
      continue;
    }

    if (Keyword == Ident_unavailable) {
      if (UnavailableLoc.isValid()) {
        Diag(KeywordLoc, diag::err_availability_redundant)
          << Keyword << SourceRange(UnavailableLoc);
      }
      UnavailableLoc = KeywordLoc;
      continue;
    }

    if (Keyword == Ident_deprecated && Platform->Ident &&
        Platform->Ident->isStr("swift")) {
      // For swift, we deprecate for all versions.
      if (Changes[Deprecated].KeywordLoc.isValid()) {
        Diag(KeywordLoc, diag::err_availability_redundant)
          << Keyword
          << SourceRange(Changes[Deprecated].KeywordLoc);
      }

      Changes[Deprecated].KeywordLoc = KeywordLoc;
      // Use a fake version here.
      Changes[Deprecated].Version = VersionTuple(1);
      continue;
    }

    if (Tok.isNot(tok::equal)) {
      Diag(Tok, diag::err_expected_after) << Keyword << tok::equal;
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }
    ConsumeToken();
    if (Keyword == Ident_message || Keyword == Ident_replacement) {
      if (Tok.isNot(tok::string_literal)) {
        Diag(Tok, diag::err_expected_string_literal)
          << /*Source='availability attribute'*/2;
        SkipUntil(tok::r_paren, StopAtSemi);
        return;
      }
      if (Keyword == Ident_message)
        MessageExpr = ParseStringLiteralExpression();
      else
        ReplacementExpr = ParseStringLiteralExpression();
      // Also reject wide string literals.
      if (StringLiteral *MessageStringLiteral =
              cast_or_null<StringLiteral>(MessageExpr.get())) {
        if (!MessageStringLiteral->isOrdinary()) {
          Diag(MessageStringLiteral->getSourceRange().getBegin(),
               diag::err_expected_string_literal)
            << /*Source='availability attribute'*/ 2;
          SkipUntil(tok::r_paren, StopAtSemi);
          return;
        }
      }
      if (Keyword == Ident_message)
        break;
      else
        continue;
    }

    // Special handling of 'NA' only when applied to introduced or
    // deprecated.
    if ((Keyword == Ident_introduced || Keyword == Ident_deprecated) &&
        Tok.is(tok::identifier)) {
      IdentifierInfo *NA = Tok.getIdentifierInfo();
      if (NA->getName() == "NA") {
        ConsumeToken();
        if (Keyword == Ident_introduced)
          UnavailableLoc = KeywordLoc;
        continue;
      }
    }

    SourceRange VersionRange;
    VersionTuple Version = ParseVersionTuple(VersionRange);

    if (Version.empty()) {
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }

    unsigned Index;
    if (Keyword == Ident_introduced)
      Index = Introduced;
    else if (Keyword == Ident_deprecated)
      Index = Deprecated;
    else if (Keyword == Ident_obsoleted)
      Index = Obsoleted;
    else
      Index = Unknown;

    if (Index < Unknown) {
      if (!Changes[Index].KeywordLoc.isInvalid()) {
        Diag(KeywordLoc, diag::err_availability_redundant)
          << Keyword
          << SourceRange(Changes[Index].KeywordLoc,
                         Changes[Index].VersionRange.getEnd());
      }

      Changes[Index].KeywordLoc = KeywordLoc;
      Changes[Index].Version = Version;
      Changes[Index].VersionRange = VersionRange;
    } else {
      Diag(KeywordLoc, diag::err_availability_unknown_change)
        << Keyword << VersionRange;
    }

  } while (TryConsumeToken(tok::comma));

  // Closing ')'.
  if (T.consumeClose())
    return;

  if (endLoc)
    *endLoc = T.getCloseLocation();

  // The 'unavailable' availability cannot be combined with any other
  // availability changes. Make sure that hasn't happened.
  if (UnavailableLoc.isValid()) {
    bool Complained = false;
    for (unsigned Index = Introduced; Index != Unknown; ++Index) {
      if (Changes[Index].KeywordLoc.isValid()) {
        if (!Complained) {
          Diag(UnavailableLoc, diag::warn_availability_and_unavailable)
            << SourceRange(Changes[Index].KeywordLoc,
                           Changes[Index].VersionRange.getEnd());
          Complained = true;
        }

        // Clear out the availability.
        Changes[Index] = AvailabilityChange();
      }
    }
  }

  // Record this attribute
  attrs.addNew(&Availability,
               SourceRange(AvailabilityLoc, T.getCloseLocation()), ScopeName,
               ScopeLoc, Platform, Changes[Introduced], Changes[Deprecated],
               Changes[Obsoleted], UnavailableLoc, MessageExpr.get(), Form,
               StrictLoc, ReplacementExpr.get());
}

/// Parse the contents of the "external_source_symbol" attribute.
///
/// external-source-symbol-attribute:
///   'external_source_symbol' '(' keyword-arg-list ')'
///
/// keyword-arg-list:
///   keyword-arg
///   keyword-arg ',' keyword-arg-list
///
/// keyword-arg:
///   'language' '=' <string>
///   'defined_in' '=' <string>
///   'USR' '=' <string>
///   'generated_declaration'
void Parser::ParseExternalSourceSymbolAttribute(
    IdentifierInfo &ExternalSourceSymbol, SourceLocation Loc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  // Opening '('.
  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.expectAndConsume())
    return;

  // Initialize the pointers for the keyword identifiers when required.
  if (!Ident_language) {
    Ident_language = PP.getIdentifierInfo("language");
    Ident_defined_in = PP.getIdentifierInfo("defined_in");
    Ident_generated_declaration = PP.getIdentifierInfo("generated_declaration");
    Ident_USR = PP.getIdentifierInfo("USR");
  }

  ExprResult Language;
  bool HasLanguage = false;
  ExprResult DefinedInExpr;
  bool HasDefinedIn = false;
  IdentifierLoc *GeneratedDeclaration = nullptr;
  ExprResult USR;
  bool HasUSR = false;

  // Parse the language/defined_in/generated_declaration keywords
  do {
    if (Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_external_source_symbol_expected_keyword);
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }

    SourceLocation KeywordLoc = Tok.getLocation();
    IdentifierInfo *Keyword = Tok.getIdentifierInfo();
    if (Keyword == Ident_generated_declaration) {
      if (GeneratedDeclaration) {
        Diag(Tok, diag::err_external_source_symbol_duplicate_clause) << Keyword;
        SkipUntil(tok::r_paren, StopAtSemi);
        return;
      }
      GeneratedDeclaration = ParseIdentifierLoc();
      continue;
    }

    if (Keyword != Ident_language && Keyword != Ident_defined_in &&
        Keyword != Ident_USR) {
      Diag(Tok, diag::err_external_source_symbol_expected_keyword);
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }

    ConsumeToken();
    if (ExpectAndConsume(tok::equal, diag::err_expected_after,
                         Keyword->getName())) {
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }

    bool HadLanguage = HasLanguage, HadDefinedIn = HasDefinedIn,
         HadUSR = HasUSR;
    if (Keyword == Ident_language)
      HasLanguage = true;
    else if (Keyword == Ident_USR)
      HasUSR = true;
    else
      HasDefinedIn = true;

    if (Tok.isNot(tok::string_literal)) {
      Diag(Tok, diag::err_expected_string_literal)
          << /*Source='external_source_symbol attribute'*/ 3
          << /*language | source container | USR*/ (
                 Keyword == Ident_language
                     ? 0
                     : (Keyword == Ident_defined_in ? 1 : 2));
      SkipUntil(tok::comma, tok::r_paren, StopAtSemi | StopBeforeMatch);
      continue;
    }
    if (Keyword == Ident_language) {
      if (HadLanguage) {
        Diag(KeywordLoc, diag::err_external_source_symbol_duplicate_clause)
            << Keyword;
        ParseStringLiteralExpression();
        continue;
      }
      Language = ParseStringLiteralExpression();
    } else if (Keyword == Ident_USR) {
      if (HadUSR) {
        Diag(KeywordLoc, diag::err_external_source_symbol_duplicate_clause)
            << Keyword;
        ParseStringLiteralExpression();
        continue;
      }
      USR = ParseStringLiteralExpression();
    } else {
      assert(Keyword == Ident_defined_in && "Invalid clause keyword!");
      if (HadDefinedIn) {
        Diag(KeywordLoc, diag::err_external_source_symbol_duplicate_clause)
            << Keyword;
        ParseStringLiteralExpression();
        continue;
      }
      DefinedInExpr = ParseStringLiteralExpression();
    }
  } while (TryConsumeToken(tok::comma));

  // Closing ')'.
  if (T.consumeClose())
    return;
  if (EndLoc)
    *EndLoc = T.getCloseLocation();

  ArgsUnion Args[] = {Language.get(), DefinedInExpr.get(), GeneratedDeclaration,
                      USR.get()};
  Attrs.addNew(&ExternalSourceSymbol, SourceRange(Loc, T.getCloseLocation()),
               ScopeName, ScopeLoc, Args, std::size(Args), Form);
}

/// Parse the contents of the "objc_bridge_related" attribute.
/// objc_bridge_related '(' related_class ',' opt-class_method ',' opt-instance_method ')'
/// related_class:
///     Identifier
///
/// opt-class_method:
///     Identifier: | <empty>
///
/// opt-instance_method:
///     Identifier | <empty>
///
void Parser::ParseObjCBridgeRelatedAttribute(
    IdentifierInfo &ObjCBridgeRelated, SourceLocation ObjCBridgeRelatedLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  // Opening '('.
  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.consumeOpen()) {
    Diag(Tok, diag::err_expected) << tok::l_paren;
    return;
  }

  // Parse the related class name.
  if (Tok.isNot(tok::identifier)) {
    Diag(Tok, diag::err_objcbridge_related_expected_related_class);
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }
  IdentifierLoc *RelatedClass = ParseIdentifierLoc();
  if (ExpectAndConsume(tok::comma)) {
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }

  // Parse class method name.  It's non-optional in the sense that a trailing
  // comma is required, but it can be the empty string, and then we record a
  // nullptr.
  IdentifierLoc *ClassMethod = nullptr;
  if (Tok.is(tok::identifier)) {
    ClassMethod = ParseIdentifierLoc();
    if (!TryConsumeToken(tok::colon)) {
      Diag(Tok, diag::err_objcbridge_related_selector_name);
      SkipUntil(tok::r_paren, StopAtSemi);
      return;
    }
  }
  if (!TryConsumeToken(tok::comma)) {
    if (Tok.is(tok::colon))
      Diag(Tok, diag::err_objcbridge_related_selector_name);
    else
      Diag(Tok, diag::err_expected) << tok::comma;
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }

  // Parse instance method name.  Also non-optional but empty string is
  // permitted.
  IdentifierLoc *InstanceMethod = nullptr;
  if (Tok.is(tok::identifier))
    InstanceMethod = ParseIdentifierLoc();
  else if (Tok.isNot(tok::r_paren)) {
    Diag(Tok, diag::err_expected) << tok::r_paren;
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }

  // Closing ')'.
  if (T.consumeClose())
    return;

  if (EndLoc)
    *EndLoc = T.getCloseLocation();

  // Record this attribute
  Attrs.addNew(&ObjCBridgeRelated,
               SourceRange(ObjCBridgeRelatedLoc, T.getCloseLocation()),
               ScopeName, ScopeLoc, RelatedClass, ClassMethod, InstanceMethod,
               Form);
}

void Parser::ParseSwiftNewTypeAttribute(
    IdentifierInfo &AttrName, SourceLocation AttrNameLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  BalancedDelimiterTracker T(*this, tok::l_paren);

  // Opening '('
  if (T.consumeOpen()) {
    Diag(Tok, diag::err_expected) << tok::l_paren;
    return;
  }

  if (Tok.is(tok::r_paren)) {
    Diag(Tok.getLocation(), diag::err_argument_required_after_attribute);
    T.consumeClose();
    return;
  }
  if (Tok.isNot(tok::kw_struct) && Tok.isNot(tok::kw_enum)) {
    Diag(Tok, diag::warn_attribute_type_not_supported)
        << &AttrName << Tok.getIdentifierInfo();
    if (!isTokenSpecial())
      ConsumeToken();
    T.consumeClose();
    return;
  }

  auto *SwiftType = IdentifierLoc::create(Actions.Context, Tok.getLocation(),
                                          Tok.getIdentifierInfo());
  ConsumeToken();

  // Closing ')'
  if (T.consumeClose())
    return;
  if (EndLoc)
    *EndLoc = T.getCloseLocation();

  ArgsUnion Args[] = {SwiftType};
  Attrs.addNew(&AttrName, SourceRange(AttrNameLoc, T.getCloseLocation()),
               ScopeName, ScopeLoc, Args, std::size(Args), Form);
}

void Parser::ParseTypeTagForDatatypeAttribute(
    IdentifierInfo &AttrName, SourceLocation AttrNameLoc,
    ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
    SourceLocation ScopeLoc, ParsedAttr::Form Form) {
  assert(Tok.is(tok::l_paren) && "Attribute arg list not starting with '('");

  BalancedDelimiterTracker T(*this, tok::l_paren);
  T.consumeOpen();

  if (Tok.isNot(tok::identifier)) {
    Diag(Tok, diag::err_expected) << tok::identifier;
    T.skipToEnd();
    return;
  }
  IdentifierLoc *ArgumentKind = ParseIdentifierLoc();

  if (ExpectAndConsume(tok::comma)) {
    T.skipToEnd();
    return;
  }

  SourceRange MatchingCTypeRange;
  TypeResult MatchingCType = ParseTypeName(&MatchingCTypeRange);
  if (MatchingCType.isInvalid()) {
    T.skipToEnd();
    return;
  }

  bool LayoutCompatible = false;
  bool MustBeNull = false;
  while (TryConsumeToken(tok::comma)) {
    if (Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_expected) << tok::identifier;
      T.skipToEnd();
      return;
    }
    IdentifierInfo *Flag = Tok.getIdentifierInfo();
    if (Flag->isStr("layout_compatible"))
      LayoutCompatible = true;
    else if (Flag->isStr("must_be_null"))
      MustBeNull = true;
    else {
      Diag(Tok, diag::err_type_safety_unknown_flag) << Flag;
      T.skipToEnd();
      return;
    }
    ConsumeToken(); // consume flag
  }

  if (!T.consumeClose()) {
    Attrs.addNewTypeTagForDatatype(&AttrName, AttrNameLoc, ScopeName, ScopeLoc,
                                   ArgumentKind, MatchingCType.get(),
                                   LayoutCompatible, MustBeNull, Form);
  }

  if (EndLoc)
    *EndLoc = T.getCloseLocation();
}

/// DiagnoseProhibitedCXX11Attribute - We have found the opening square brackets
/// of a C++11 attribute-specifier in a location where an attribute is not
/// permitted. By C++11 [dcl.attr.grammar]p6, this is ill-formed. Diagnose this
/// situation.
///
/// \return \c true if we skipped an attribute-like chunk of tokens, \c false if
/// this doesn't appear to actually be an attribute-specifier, and the caller
/// should try to parse it.
bool Parser::DiagnoseProhibitedCXX11Attribute() {
  assert(Tok.is(tok::l_square) && NextToken().is(tok::l_square));

  switch (isCXX11AttributeSpecifier(/*Disambiguate*/true)) {
  case CAK_NotAttributeSpecifier:
    // No diagnostic: we're in Obj-C++11 and this is not actually an attribute.
    return false;

  case CAK_InvalidAttributeSpecifier:
    Diag(Tok.getLocation(), diag::err_l_square_l_square_not_attribute);
    return false;

  case CAK_AttributeSpecifier:
    // Parse and discard the attributes.
    SourceLocation BeginLoc = ConsumeBracket();
    ConsumeBracket();
    SkipUntil(tok::r_square);
    assert(Tok.is(tok::r_square) && "isCXX11AttributeSpecifier lied");
    SourceLocation EndLoc = ConsumeBracket();
    Diag(BeginLoc, diag::err_attributes_not_allowed)
      << SourceRange(BeginLoc, EndLoc);
    return true;
  }
  llvm_unreachable("All cases handled above.");
}

/// We have found the opening square brackets of a C++11
/// attribute-specifier in a location where an attribute is not permitted, but
/// we know where the attributes ought to be written. Parse them anyway, and
/// provide a fixit moving them to the right place.
void Parser::DiagnoseMisplacedCXX11Attribute(ParsedAttributes &Attrs,
                                             SourceLocation CorrectLocation) {
  assert((Tok.is(tok::l_square) && NextToken().is(tok::l_square)) ||
         Tok.is(tok::kw_alignas) || Tok.isRegularKeywordAttribute());

  // Consume the attributes.
  auto Keyword =
      Tok.isRegularKeywordAttribute() ? Tok.getIdentifierInfo() : nullptr;
  SourceLocation Loc = Tok.getLocation();
  ParseCXX11Attributes(Attrs);
  CharSourceRange AttrRange(SourceRange(Loc, Attrs.Range.getEnd()), true);
  // FIXME: use err_attributes_misplaced
  (Keyword ? Diag(Loc, diag::err_keyword_not_allowed) << Keyword
           : Diag(Loc, diag::err_attributes_not_allowed))
      << FixItHint::CreateInsertionFromRange(CorrectLocation, AttrRange)
      << FixItHint::CreateRemoval(AttrRange);
}

void Parser::DiagnoseProhibitedAttributes(
    const ParsedAttributesView &Attrs, const SourceLocation CorrectLocation) {
  auto *FirstAttr = Attrs.empty() ? nullptr : &Attrs.front();
  if (CorrectLocation.isValid()) {
    CharSourceRange AttrRange(Attrs.Range, true);
    (FirstAttr && FirstAttr->isRegularKeywordAttribute()
         ? Diag(CorrectLocation, diag::err_keyword_misplaced) << FirstAttr
         : Diag(CorrectLocation, diag::err_attributes_misplaced))
        << FixItHint::CreateInsertionFromRange(CorrectLocation, AttrRange)
        << FixItHint::CreateRemoval(AttrRange);
  } else {
    const SourceRange &Range = Attrs.Range;
    (FirstAttr && FirstAttr->isRegularKeywordAttribute()
         ? Diag(Range.getBegin(), diag::err_keyword_not_allowed) << FirstAttr
         : Diag(Range.getBegin(), diag::err_attributes_not_allowed))
        << Range;
  }
}

void Parser::ProhibitCXX11Attributes(ParsedAttributes &Attrs,
                                     unsigned AttrDiagID,
                                     unsigned KeywordDiagID,
                                     bool DiagnoseEmptyAttrs,
                                     bool WarnOnUnknownAttrs) {

  if (DiagnoseEmptyAttrs && Attrs.empty() && Attrs.Range.isValid()) {
    // An attribute list has been parsed, but it was empty.
    // This is the case for [[]].
    const auto &LangOpts = getLangOpts();
    auto &SM = PP.getSourceManager();
    Token FirstLSquare;
    Lexer::getRawToken(Attrs.Range.getBegin(), FirstLSquare, SM, LangOpts);

    if (FirstLSquare.is(tok::l_square)) {
      std::optional<Token> SecondLSquare =
          Lexer::findNextToken(FirstLSquare.getLocation(), SM, LangOpts);

      if (SecondLSquare && SecondLSquare->is(tok::l_square)) {
        // The attribute range starts with [[, but is empty. So this must
        // be [[]], which we are supposed to diagnose because
        // DiagnoseEmptyAttrs is true.
        Diag(Attrs.Range.getBegin(), AttrDiagID) << Attrs.Range;
        return;
      }
    }
  }

  for (const ParsedAttr &AL : Attrs) {
    if (AL.isRegularKeywordAttribute()) {
      Diag(AL.getLoc(), KeywordDiagID) << AL;
      AL.setInvalid();
      continue;
    }
    if (!AL.isCXX11Attribute() && !AL.isC2xAttribute())
      continue;
    if (AL.getKind() == ParsedAttr::UnknownAttribute) {
      if (WarnOnUnknownAttrs)
        Diag(AL.getLoc(), diag::warn_unknown_attribute_ignored)
            << AL << AL.getRange();
    } else {
      Diag(AL.getLoc(), AttrDiagID) << AL;
      AL.setInvalid();
    }
  }
}

void Parser::DiagnoseCXX11AttributeExtension(ParsedAttributes &Attrs) {
  for (const ParsedAttr &PA : Attrs) {
    if (PA.isCXX11Attribute() || PA.isC2xAttribute() ||
        PA.isRegularKeywordAttribute())
      Diag(PA.getLoc(), diag::ext_cxx11_attr_placement)
          << PA << PA.isRegularKeywordAttribute() << PA.getRange();
  }
}

// Usually, `__attribute__((attrib)) class Foo {} var` means that attribute
// applies to var, not the type Foo.
// As an exception to the rule, __declspec(align(...)) before the
// class-key affects the type instead of the variable.
// Also, Microsoft-style [attributes] seem to affect the type instead of the
// variable.
// This function moves attributes that should apply to the type off DS to Attrs.
void Parser::stripTypeAttributesOffDeclSpec(ParsedAttributes &Attrs,
                                            DeclSpec &DS,
                                            Sema::TagUseKind TUK) {
  if (TUK == Sema::TUK_Reference)
    return;

  llvm::SmallVector<ParsedAttr *, 1> ToBeMoved;

  for (ParsedAttr &AL : DS.getAttributes()) {
    if ((AL.getKind() == ParsedAttr::AT_Aligned &&
         AL.isDeclspecAttribute()) ||
        AL.isMicrosoftAttribute())
      ToBeMoved.push_back(&AL);
  }

  for (ParsedAttr *AL : ToBeMoved) {
    DS.getAttributes().remove(AL);
    Attrs.addAtEnd(AL);
  }
}

/// ParseDeclaration - Parse a full 'declaration', which consists of
/// declaration-specifiers, some number of declarators, and a semicolon.
/// 'Context' should be a DeclaratorContext value.  This returns the
/// location of the semicolon in DeclEnd.
///
///       declaration: [C99 6.7]
///         block-declaration ->
///           simple-declaration
///           others                   [FIXME]
/// [C++]   template-declaration
/// [C++]   namespace-definition
/// [C++]   using-directive
/// [C++]   using-declaration
/// [C++11/C11] static_assert-declaration
///         others... [FIXME]
///
Parser::DeclGroupPtrTy Parser::ParseDeclaration(DeclaratorContext Context,
                                                SourceLocation &DeclEnd,
                                                ParsedAttributes &DeclAttrs,
                                                ParsedAttributes &DeclSpecAttrs,
                                                SourceLocation *DeclSpecStart) {
  ParenBraceBracketBalancer BalancerRAIIObj(*this);
  // Must temporarily exit the objective-c container scope for
  // parsing c none objective-c decls.
  ObjCDeclContextSwitch ObjCDC(*this);

  Decl *SingleDecl = nullptr;
  switch (Tok.getKind()) {
  case tok::kw_template:
  case tok::kw_export:
    ProhibitAttributes(DeclAttrs);
    ProhibitAttributes(DeclSpecAttrs);
    SingleDecl =
        ParseDeclarationStartingWithTemplate(Context, DeclEnd, DeclAttrs);
    break;
  case tok::kw_inline:
    // Could be the start of an inline namespace. Allowed as an ext in C++03.
    if (getLangOpts().CPlusPlus && NextToken().is(tok::kw_namespace)) {
      ProhibitAttributes(DeclAttrs);
      ProhibitAttributes(DeclSpecAttrs);
      SourceLocation InlineLoc = ConsumeToken();
      return ParseNamespace(Context, DeclEnd, InlineLoc);
    }
    return ParseSimpleDeclaration(Context, DeclEnd, DeclAttrs, DeclSpecAttrs,
                                  true, nullptr, DeclSpecStart);

  case tok::kw_cbuffer:
  case tok::kw_tbuffer:
    SingleDecl = ParseHLSLBuffer(DeclEnd);
    break;
  case tok::kw_namespace:
    ProhibitAttributes(DeclAttrs);
    ProhibitAttributes(DeclSpecAttrs);
    return ParseNamespace(Context, DeclEnd);
  case tok::kw_using: {
    ParsedAttributes Attrs(AttrFactory);
    takeAndConcatenateAttrs(DeclAttrs, DeclSpecAttrs, Attrs);
    return ParseUsingDirectiveOrDeclaration(Context, ParsedTemplateInfo(),
                                            DeclEnd, Attrs);
  }
  case tok::kw_static_assert:
  case tok::kw__Static_assert:
    ProhibitAttributes(DeclAttrs);
    ProhibitAttributes(DeclSpecAttrs);
    SingleDecl = ParseStaticAssertDeclaration(DeclEnd);
    break;
  default:
    return ParseSimpleDeclaration(Context, DeclEnd, DeclAttrs, DeclSpecAttrs,
                                  true, nullptr, DeclSpecStart);
  }

  // This routine returns a DeclGroup, if the thing we parsed only contains a
  // single decl, convert it now.
  return Actions.ConvertDeclToDeclGroup(SingleDecl);
}

///       simple-declaration: [C99 6.7: declaration] [C++ 7p1: dcl.dcl]
///         declaration-specifiers init-declarator-list[opt] ';'
/// [C++11] attribute-specifier-seq decl-specifier-seq[opt]
///             init-declarator-list ';'
///[C90/C++]init-declarator-list ';'                             [TODO]
/// [OMP]   threadprivate-directive
/// [OMP]   allocate-directive                                   [TODO]
///
///       for-range-declaration: [C++11 6.5p1: stmt.ranged]
///         attribute-specifier-seq[opt] type-specifier-seq declarator
///
/// If RequireSemi is false, this does not check for a ';' at the end of the
/// declaration.  If it is true, it checks for and eats it.
///
/// If FRI is non-null, we might be parsing a for-range-declaration instead
/// of a simple-declaration. If we find that we are, we also parse the
/// for-range-initializer, and place it here.
///
/// DeclSpecStart is used when decl-specifiers are parsed before parsing
/// the Declaration. The SourceLocation for this Decl is set to
/// DeclSpecStart if DeclSpecStart is non-null.
Parser::DeclGroupPtrTy Parser::ParseSimpleDeclaration(
    DeclaratorContext Context, SourceLocation &DeclEnd,
    ParsedAttributes &DeclAttrs, ParsedAttributes &DeclSpecAttrs,
    bool RequireSemi, ForRangeInit *FRI, SourceLocation *DeclSpecStart) {
  // Need to retain these for diagnostics before we add them to the DeclSepc.
  ParsedAttributesView OriginalDeclSpecAttrs;
  OriginalDeclSpecAttrs.addAll(DeclSpecAttrs.begin(), DeclSpecAttrs.end());
  OriginalDeclSpecAttrs.Range = DeclSpecAttrs.Range;

  // Parse the common declaration-specifiers piece.
  ParsingDeclSpec DS(*this);
  DS.takeAttributesFrom(DeclSpecAttrs);

  DeclSpecContext DSContext = getDeclSpecContextFromDeclaratorContext(Context);
  ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS_none, DSContext);

  // If we had a free-standing type definition with a missing semicolon, we
  // may get this far before the problem becomes obvious.
  if (DS.hasTagDefinition() &&
      DiagnoseMissingSemiAfterTagDefinition(DS, AS_none, DSContext))
    return nullptr;

  // C99 6.7.2.3p6: Handle "struct-or-union identifier;", "enum { X };"
  // declaration-specifiers init-declarator-list[opt] ';'
  if (Tok.is(tok::semi)) {
    ProhibitAttributes(DeclAttrs);
    DeclEnd = Tok.getLocation();
    if (RequireSemi) ConsumeToken();
    RecordDecl *AnonRecord = nullptr;
    Decl *TheDecl = Actions.ParsedFreeStandingDeclSpec(
        getCurScope(), AS_none, DS, ParsedAttributesView::none(), AnonRecord);
    DS.complete(TheDecl);
    if (AnonRecord) {
      Decl* decls[] = {AnonRecord, TheDecl};
      return Actions.BuildDeclaratorGroup(decls);
    }
    return Actions.ConvertDeclToDeclGroup(TheDecl);
  }

  if (DeclSpecStart)
    DS.SetRangeStart(*DeclSpecStart);

  return ParseDeclGroup(DS, Context, DeclAttrs, &DeclEnd, FRI);
}

/// Returns true if this might be the start of a declarator, or a common typo
/// for a declarator.
bool Parser::MightBeDeclarator(DeclaratorContext Context) {
  switch (Tok.getKind()) {
  case tok::annot_cxxscope:
  case tok::annot_template_id:
  case tok::caret:
  case tok::code_completion:
  case tok::coloncolon:
  case tok::ellipsis:
  case tok::kw___attribute:
  case tok::kw_operator:
  case tok::l_paren:
  case tok::star:
    return true;

  case tok::amp:
  case tok::ampamp:
    return getLangOpts().CPlusPlus;

  case tok::l_square: // Might be an attribute on an unnamed bit-field.
    return Context == DeclaratorContext::Member && getLangOpts().CPlusPlus11 &&
           NextToken().is(tok::l_square);

  case tok::colon: // Might be a typo for '::' or an unnamed bit-field.
    return Context == DeclaratorContext::Member || getLangOpts().CPlusPlus;

  case tok::identifier:
    switch (NextToken().getKind()) {
    case tok::code_completion:
    case tok::coloncolon:
    case tok::comma:
    case tok::equal:
    case tok::equalequal: // Might be a typo for '='.
    case tok::kw_alignas:
    case tok::kw_asm:
    case tok::kw___attribute:
    case tok::l_brace:
    case tok::l_paren:
    case tok::l_square:
    case tok::less:
    case tok::r_brace:
    case tok::r_paren:
    case tok::r_square:
    case tok::semi:
      return true;

    case tok::colon:
      // At namespace scope, 'identifier:' is probably a typo for 'identifier::'
      // and in block scope it's probably a label. Inside a class definition,
      // this is a bit-field.
      return Context == DeclaratorContext::Member ||
             (getLangOpts().CPlusPlus && Context == DeclaratorContext::File);

    case tok::identifier: // Possible virt-specifier.
      return getLangOpts().CPlusPlus11 && isCXX11VirtSpecifier(NextToken());

    default:
      return Tok.isRegularKeywordAttribute();
    }

  default:
    return Tok.isRegularKeywordAttribute();
  }
}

/// Skip until we reach something which seems like a sensible place to pick
/// up parsing after a malformed declaration. This will sometimes stop sooner
/// than SkipUntil(tok::r_brace) would, but will never stop later.
void Parser::SkipMalformedDecl() {
  while (true) {
    switch (Tok.getKind()) {
    case tok::l_brace:
      // Skip until matching }, then stop. We've probably skipped over
      // a malformed class or function definition or similar.
      ConsumeBrace();
      SkipUntil(tok::r_brace);
      if (Tok.isOneOf(tok::comma, tok::l_brace, tok::kw_try)) {
        // This declaration isn't over yet. Keep skipping.
        continue;
      }
      TryConsumeToken(tok::semi);
      return;

    case tok::l_square:
      ConsumeBracket();
      SkipUntil(tok::r_square);
      continue;

    case tok::l_paren:
      ConsumeParen();
      SkipUntil(tok::r_paren);
      continue;

    case tok::r_brace:
      return;

    case tok::semi:
      ConsumeToken();
      return;

    case tok::kw_inline:
      // 'inline namespace' at the start of a line is almost certainly
      // a good place to pick back up parsing, except in an Objective-C
      // @interface context.
      if (Tok.isAtStartOfLine() && NextToken().is(tok::kw_namespace) &&
          (!ParsingInObjCContainer || CurParsedObjCImpl))
        return;
      break;

    case tok::kw_namespace:
      // 'namespace' at the start of a line is almost certainly a good
      // place to pick back up parsing, except in an Objective-C
      // @interface context.
      if (Tok.isAtStartOfLine() &&
          (!ParsingInObjCContainer || CurParsedObjCImpl))
        return;
      break;

    case tok::at:
      // @end is very much like } in Objective-C contexts.
      if (NextToken().isObjCAtKeyword(tok::objc_end) &&
          ParsingInObjCContainer)
        return;
      break;

    case tok::minus:
    case tok::plus:
      // - and + probably start new method declarations in Objective-C contexts.
      if (Tok.isAtStartOfLine() && ParsingInObjCContainer)
        return;
      break;

    case tok::eof:
    case tok::annot_module_begin:
    case tok::annot_module_end:
    case tok::annot_module_include:
    case tok::annot_repl_input_end:
      return;

    default:
      break;
    }

    ConsumeAnyToken();
  }
}

/// ParseDeclGroup - Having concluded that this is either a function
/// definition or a group of object declarations, actually parse the
/// result.
Parser::DeclGroupPtrTy Parser::ParseDeclGroup(ParsingDeclSpec &DS,
                                              DeclaratorContext Context,
                                              ParsedAttributes &Attrs,
                                              SourceLocation *DeclEnd,
                                              ForRangeInit *FRI) {
  // Parse the first declarator.
  // Consume all of the attributes from `Attrs` by moving them to our own local
  // list. This ensures that we will not attempt to interpret them as statement
  // attributes higher up the callchain.
  ParsedAttributes LocalAttrs(AttrFactory);
  LocalAttrs.takeAllFrom(Attrs);
  ParsingDeclarator D(*this, DS, LocalAttrs, Context);
  ParseDeclarator(D);

  // Bail out if the first declarator didn't seem well-formed.
  if (!D.hasName() && !D.mayOmitIdentifier()) {
    SkipMalformedDecl();
    return nullptr;
  }

  if (getLangOpts().HLSL)
    MaybeParseHLSLSemantics(D);

  if (Tok.is(tok::kw_requires))
    ParseTrailingRequiresClause(D);

  // Save late-parsed attributes for now; they need to be parsed in the
  // appropriate function scope after the function Decl has been constructed.
  // These will be parsed in ParseFunctionDefinition or ParseLexedAttrList.
  LateParsedAttrList LateParsedAttrs(true);
  if (D.isFunctionDeclarator()) {
    MaybeParseGNUAttributes(D, &LateParsedAttrs);

    // The _Noreturn keyword can't appear here, unlike the GNU noreturn
    // attribute. If we find the keyword here, tell the user to put it
    // at the start instead.
    if (Tok.is(tok::kw__Noreturn)) {
      SourceLocation Loc = ConsumeToken();
      const char *PrevSpec;
      unsigned DiagID;

      // We can offer a fixit if it's valid to mark this function as _Noreturn
      // and we don't have any other declarators in this declaration.
      bool Fixit = !DS.setFunctionSpecNoreturn(Loc, PrevSpec, DiagID);
      MaybeParseGNUAttributes(D, &LateParsedAttrs);
      Fixit &= Tok.isOneOf(tok::semi, tok::l_brace, tok::kw_try);

      Diag(Loc, diag::err_c11_noreturn_misplaced)
          << (Fixit ? FixItHint::CreateRemoval(Loc) : FixItHint())
          << (Fixit ? FixItHint::CreateInsertion(D.getBeginLoc(), "_Noreturn ")
                    : FixItHint());
    }

    // Check to see if we have a function *definition* which must have a body.
    if (Tok.is(tok::equal) && NextToken().is(tok::code_completion)) {
      cutOffParsing();
      Actions.CodeCompleteAfterFunctionEquals(D);
      return nullptr;
    }
    // We're at the point where the parsing of function declarator is finished.
    //
    // A common error is that users accidently add a virtual specifier
    // (e.g. override) in an out-line method definition.
    // We attempt to recover by stripping all these specifiers coming after
    // the declarator.
    while (auto Specifier = isCXX11VirtSpecifier()) {
      Diag(Tok, diag::err_virt_specifier_outside_class)
          << VirtSpecifiers::getSpecifierName(Specifier)
          << FixItHint::CreateRemoval(Tok.getLocation());
      ConsumeToken();
    }
    // Look at the next token to make sure that this isn't a function
    // declaration.  We have to check this because __attribute__ might be the
    // start of a function definition in GCC-extended K&R C.
    if (!isDeclarationAfterDeclarator()) {

      // Function definitions are only allowed at file scope and in C++ classes.
      // The C++ inline method definition case is handled elsewhere, so we only
      // need to handle the file scope definition case.
      if (Context == DeclaratorContext::File) {
        if (isStartOfFunctionDefinition(D)) {
          if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
            Diag(Tok, diag::err_function_declared_typedef);

            // Recover by treating the 'typedef' as spurious.
            DS.ClearStorageClassSpecs();
          }

          Decl *TheDecl = ParseFunctionDefinition(D, ParsedTemplateInfo(),
                                                  &LateParsedAttrs);
          return Actions.ConvertDeclToDeclGroup(TheDecl);
        }

        if (isDeclarationSpecifier(ImplicitTypenameContext::No) ||
            Tok.is(tok::kw_namespace)) {
          // If there is an invalid declaration specifier or a namespace
          // definition right after the function prototype, then we must be in a
          // missing semicolon case where this isn't actually a body.  Just fall
          // through into the code that handles it as a prototype, and let the
          // top-level code handle the erroneous declspec where it would
          // otherwise expect a comma or semicolon. Note that
          // isDeclarationSpecifier already covers 'inline namespace', since
          // 'inline' can be a declaration specifier.
        } else {
          Diag(Tok, diag::err_expected_fn_body);
          SkipUntil(tok::semi);
          return nullptr;
        }
      } else {
        if (Tok.is(tok::l_brace)) {
          Diag(Tok, diag::err_function_definition_not_allowed);
          SkipMalformedDecl();
          return nullptr;
        }
      }
    }
  }

  if (ParseAsmAttributesAfterDeclarator(D))
    return nullptr;

  // C++0x [stmt.iter]p1: Check if we have a for-range-declarator. If so, we
  // must parse and analyze the for-range-initializer before the declaration is
  // analyzed.
  //
  // Handle the Objective-C for-in loop variable similarly, although we
  // don't need to parse the container in advance.
  if (FRI && (Tok.is(tok::colon) || isTokIdentifier_in())) {
    bool IsForRangeLoop = false;
    if (TryConsumeToken(tok::colon, FRI->ColonLoc)) {
      IsForRangeLoop = true;
      if (getLangOpts().OpenMP)
        Actions.startOpenMPCXXRangeFor();
      if (Tok.is(tok::l_brace))
        FRI->RangeExpr = ParseBraceInitializer();
      else
        FRI->RangeExpr = ParseExpression();
    }

    Decl *ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
    if (IsForRangeLoop) {
      Actions.ActOnCXXForRangeDecl(ThisDecl);
    } else {
      // Obj-C for loop
      if (auto *VD = dyn_cast_or_null<VarDecl>(ThisDecl))
        VD->setObjCForDecl(true);
    }
    Actions.FinalizeDeclaration(ThisDecl);
    D.complete(ThisDecl);
    return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, ThisDecl);
  }

  SmallVector<Decl *, 8> DeclsInGroup;
  Decl *FirstDecl = ParseDeclarationAfterDeclaratorAndAttributes(
      D, ParsedTemplateInfo(), FRI);
  if (LateParsedAttrs.size() > 0)
    ParseLexedAttributeList(LateParsedAttrs, FirstDecl, true, false);
  D.complete(FirstDecl);
  if (FirstDecl)
    DeclsInGroup.push_back(FirstDecl);

  bool ExpectSemi = Context != DeclaratorContext::ForInit;

  // If we don't have a comma, it is either the end of the list (a ';') or an
  // error, bail out.
  SourceLocation CommaLoc;
  while (TryConsumeToken(tok::comma, CommaLoc)) {
    if (Tok.isAtStartOfLine() && ExpectSemi && !MightBeDeclarator(Context)) {
      // This comma was followed by a line-break and something which can't be
      // the start of a declarator. The comma was probably a typo for a
      // semicolon.
      Diag(CommaLoc, diag::err_expected_semi_declaration)
        << FixItHint::CreateReplacement(CommaLoc, ";");
      ExpectSemi = false;
      break;
    }

    // Parse the next declarator.
    D.clear();
    D.setCommaLoc(CommaLoc);

    // Accept attributes in an init-declarator.  In the first declarator in a
    // declaration, these would be part of the declspec.  In subsequent
    // declarators, they become part of the declarator itself, so that they
    // don't apply to declarators after *this* one.  Examples:
    //    short __attribute__((common)) var;    -> declspec
    //    short var __attribute__((common));    -> declarator
    //    short x, __attribute__((common)) var;    -> declarator
    MaybeParseGNUAttributes(D);

    // MSVC parses but ignores qualifiers after the comma as an extension.
    if (getLangOpts().MicrosoftExt)
      DiagnoseAndSkipExtendedMicrosoftTypeAttributes();

    ParseDeclarator(D);

    if (getLangOpts().HLSL)
      MaybeParseHLSLSemantics(D);

    if (!D.isInvalidType()) {
      // C++2a [dcl.decl]p1
      //    init-declarator:
      //	      declarator initializer[opt]
      //        declarator requires-clause
      if (Tok.is(tok::kw_requires))
        ParseTrailingRequiresClause(D);
      Decl *ThisDecl = ParseDeclarationAfterDeclarator(D);
      D.complete(ThisDecl);
      if (ThisDecl)
        DeclsInGroup.push_back(ThisDecl);
    }
  }

  if (DeclEnd)
    *DeclEnd = Tok.getLocation();

  if (ExpectSemi && ExpectAndConsumeSemi(
                        Context == DeclaratorContext::File
                            ? diag::err_invalid_token_after_toplevel_declarator
                            : diag::err_expected_semi_declaration)) {
    // Okay, there was no semicolon and one was expected.  If we see a
    // declaration specifier, just assume it was missing and continue parsing.
    // Otherwise things are very confused and we skip to recover.
    if (!isDeclarationSpecifier(ImplicitTypenameContext::No))
      SkipMalformedDecl();
  }

  return Actions.FinalizeDeclaratorGroup(getCurScope(), DS, DeclsInGroup);
}

/// Parse an optional simple-asm-expr and attributes, and attach them to a
/// declarator. Returns true on an error.
bool Parser::ParseAsmAttributesAfterDeclarator(Declarator &D) {
  // If a simple-asm-expr is present, parse it.
  if (Tok.is(tok::kw_asm)) {
    SourceLocation Loc;
    ExprResult AsmLabel(ParseSimpleAsm(/*ForAsmLabel*/ true, &Loc));
    if (AsmLabel.isInvalid()) {
      SkipUntil(tok::semi, StopBeforeMatch);
      return true;
    }

    D.setAsmLabel(AsmLabel.get());
    D.SetRangeEnd(Loc);
  }

  MaybeParseGNUAttributes(D);
  return false;
}

/// Parse 'declaration' after parsing 'declaration-specifiers
/// declarator'. This method parses the remainder of the declaration
/// (including any attributes or initializer, among other things) and
/// finalizes the declaration.
///
///       init-declarator: [C99 6.7]
///         declarator
///         declarator '=' initializer
/// [GNU]   declarator simple-asm-expr[opt] attributes[opt]
/// [GNU]   declarator simple-asm-expr[opt] attributes[opt] '=' initializer
/// [C++]   declarator initializer[opt]
///
/// [C++] initializer:
/// [C++]   '=' initializer-clause
/// [C++]   '(' expression-list ')'
/// [C++0x] '=' 'default'                                                [TODO]
/// [C++0x] '=' 'delete'
/// [C++0x] braced-init-list
///
/// According to the standard grammar, =default and =delete are function
/// definitions, but that definitely doesn't fit with the parser here.
///
Decl *Parser::ParseDeclarationAfterDeclarator(
    Declarator &D, const ParsedTemplateInfo &TemplateInfo) {
  if (ParseAsmAttributesAfterDeclarator(D))
    return nullptr;

  return ParseDeclarationAfterDeclaratorAndAttributes(D, TemplateInfo);
}

Decl *Parser::ParseDeclarationAfterDeclaratorAndAttributes(
    Declarator &D, const ParsedTemplateInfo &TemplateInfo, ForRangeInit *FRI) {
  // RAII type used to track whether we're inside an initializer.
  struct InitializerScopeRAII {
    Parser &P;
    Declarator &D;
    Decl *ThisDecl;

    InitializerScopeRAII(Parser &P, Declarator &D, Decl *ThisDecl)
        : P(P), D(D), ThisDecl(ThisDecl) {
      if (ThisDecl && P.getLangOpts().CPlusPlus) {
        Scope *S = nullptr;
        if (D.getCXXScopeSpec().isSet()) {
          P.EnterScope(0);
          S = P.getCurScope();
        }
        P.Actions.ActOnCXXEnterDeclInitializer(S, ThisDecl);
      }
    }
    ~InitializerScopeRAII() { pop(); }
    void pop() {
      if (ThisDecl && P.getLangOpts().CPlusPlus) {
        Scope *S = nullptr;
        if (D.getCXXScopeSpec().isSet())
          S = P.getCurScope();
        P.Actions.ActOnCXXExitDeclInitializer(S, ThisDecl);
        if (S)
          P.ExitScope();
      }
      ThisDecl = nullptr;
    }
  };

  enum class InitKind { Uninitialized, Equal, CXXDirect, CXXBraced };
  InitKind TheInitKind;
  // If a '==' or '+=' is found, suggest a fixit to '='.
  if (isTokenEqualOrEqualTypo())
    TheInitKind = InitKind::Equal;
  else if (Tok.is(tok::l_paren))
    TheInitKind = InitKind::CXXDirect;
  else if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace) &&
           (!CurParsedObjCImpl || !D.isFunctionDeclarator()))
    TheInitKind = InitKind::CXXBraced;
  else
    TheInitKind = InitKind::Uninitialized;
  if (TheInitKind != InitKind::Uninitialized)
    D.setHasInitializer();

  // Inform Sema that we just parsed this declarator.
  Decl *ThisDecl = nullptr;
  Decl *OuterDecl = nullptr;
  switch (TemplateInfo.Kind) {
  case ParsedTemplateInfo::NonTemplate:
    ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
    break;

  case ParsedTemplateInfo::Template:
  case ParsedTemplateInfo::ExplicitSpecialization: {
    ThisDecl = Actions.ActOnTemplateDeclarator(getCurScope(),
                                               *TemplateInfo.TemplateParams,
                                               D);
    if (VarTemplateDecl *VT = dyn_cast_or_null<VarTemplateDecl>(ThisDecl)) {
      // Re-direct this decl to refer to the templated decl so that we can
      // initialize it.
      ThisDecl = VT->getTemplatedDecl();
      OuterDecl = VT;
    }
    break;
  }
  case ParsedTemplateInfo::ExplicitInstantiation: {
    if (Tok.is(tok::semi)) {
      DeclResult ThisRes = Actions.ActOnExplicitInstantiation(
          getCurScope(), TemplateInfo.ExternLoc, TemplateInfo.TemplateLoc, D);
      if (ThisRes.isInvalid()) {
        SkipUntil(tok::semi, StopBeforeMatch);
        return nullptr;
      }
      ThisDecl = ThisRes.get();
    } else {
      // FIXME: This check should be for a variable template instantiation only.

      // Check that this is a valid instantiation
      if (D.getName().getKind() != UnqualifiedIdKind::IK_TemplateId) {
        // If the declarator-id is not a template-id, issue a diagnostic and
        // recover by ignoring the 'template' keyword.
        Diag(Tok, diag::err_template_defn_explicit_instantiation)
            << 2 << FixItHint::CreateRemoval(TemplateInfo.TemplateLoc);
        ThisDecl = Actions.ActOnDeclarator(getCurScope(), D);
      } else {
        SourceLocation LAngleLoc =
            PP.getLocForEndOfToken(TemplateInfo.TemplateLoc);
        Diag(D.getIdentifierLoc(),
             diag::err_explicit_instantiation_with_definition)
            << SourceRange(TemplateInfo.TemplateLoc)
            << FixItHint::CreateInsertion(LAngleLoc, "<>");

        // Recover as if it were an explicit specialization.
        TemplateParameterLists FakedParamLists;
        FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
            0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc,
            std::nullopt, LAngleLoc, nullptr));

        ThisDecl =
            Actions.ActOnTemplateDeclarator(getCurScope(), FakedParamLists, D);
      }
    }
    break;
    }
  }

  switch (TheInitKind) {
  // Parse declarator '=' initializer.
  case InitKind::Equal: {
    SourceLocation EqualLoc = ConsumeToken();

    if (Tok.is(tok::kw_delete)) {
      if (D.isFunctionDeclarator())
        Diag(ConsumeToken(), diag::err_default_delete_in_multiple_declaration)
          << 1 /* delete */;
      else
        Diag(ConsumeToken(), diag::err_deleted_non_function);
    } else if (Tok.is(tok::kw_default)) {
      if (D.isFunctionDeclarator())
        Diag(ConsumeToken(), diag::err_default_delete_in_multiple_declaration)
          << 0 /* default */;
      else
        Diag(ConsumeToken(), diag::err_default_special_members)
            << getLangOpts().CPlusPlus20;
    } else {
      InitializerScopeRAII InitScope(*this, D, ThisDecl);

      if (Tok.is(tok::code_completion)) {
        cutOffParsing();
        Actions.CodeCompleteInitializer(getCurScope(), ThisDecl);
        Actions.FinalizeDeclaration(ThisDecl);
        return nullptr;
      }

      PreferredType.enterVariableInit(Tok.getLocation(), ThisDecl);
      ExprResult Init = ParseInitializer();

      // If this is the only decl in (possibly) range based for statement,
      // our best guess is that the user meant ':' instead of '='.
      if (Tok.is(tok::r_paren) && FRI && D.isFirstDeclarator()) {
        Diag(EqualLoc, diag::err_single_decl_assign_in_for_range)
            << FixItHint::CreateReplacement(EqualLoc, ":");
        // We are trying to stop parser from looking for ';' in this for
        // statement, therefore preventing spurious errors to be issued.
        FRI->ColonLoc = EqualLoc;
        Init = ExprError();
        FRI->RangeExpr = Init;
      }

      InitScope.pop();

      if (Init.isInvalid()) {
        SmallVector<tok::TokenKind, 2> StopTokens;
        StopTokens.push_back(tok::comma);
        if (D.getContext() == DeclaratorContext::ForInit ||
            D.getContext() == DeclaratorContext::SelectionInit)
          StopTokens.push_back(tok::r_paren);
        SkipUntil(StopTokens, StopAtSemi | StopBeforeMatch);
        Actions.ActOnInitializerError(ThisDecl);
      } else
        Actions.AddInitializerToDecl(ThisDecl, Init.get(),
                                     /*DirectInit=*/false);
    }
    break;
  }
  case InitKind::CXXDirect: {
    // Parse C++ direct initializer: '(' expression-list ')'
    BalancedDelimiterTracker T(*this, tok::l_paren);
    T.consumeOpen();

    ExprVector Exprs;

    InitializerScopeRAII InitScope(*this, D, ThisDecl);

    auto ThisVarDecl = dyn_cast_or_null<VarDecl>(ThisDecl);
    auto RunSignatureHelp = [&]() {
      QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
          ThisVarDecl->getType()->getCanonicalTypeInternal(),
          ThisDecl->getLocation(), Exprs, T.getOpenLocation(),
          /*Braced=*/false);
      CalledSignatureHelp = true;
      return PreferredType;
    };
    auto SetPreferredType = [&] {
      PreferredType.enterFunctionArgument(Tok.getLocation(), RunSignatureHelp);
    };

    llvm::function_ref<void()> ExpressionStarts;
    if (ThisVarDecl) {
      // ParseExpressionList can sometimes succeed even when ThisDecl is not
      // VarDecl. This is an error and it is reported in a call to
      // Actions.ActOnInitializerError(). However, we call
      // ProduceConstructorSignatureHelp only on VarDecls.
      ExpressionStarts = SetPreferredType;
    }
    if (ParseExpressionList(Exprs, ExpressionStarts)) {
      if (ThisVarDecl && PP.isCodeCompletionReached() && !CalledSignatureHelp) {
        Actions.ProduceConstructorSignatureHelp(
            ThisVarDecl->getType()->getCanonicalTypeInternal(),
            ThisDecl->getLocation(), Exprs, T.getOpenLocation(),
            /*Braced=*/false);
        CalledSignatureHelp = true;
      }
      Actions.ActOnInitializerError(ThisDecl);
      SkipUntil(tok::r_paren, StopAtSemi);
    } else {
      // Match the ')'.
      T.consumeClose();
      InitScope.pop();

      ExprResult Initializer = Actions.ActOnParenListExpr(T.getOpenLocation(),
                                                          T.getCloseLocation(),
                                                          Exprs);
      Actions.AddInitializerToDecl(ThisDecl, Initializer.get(),
                                   /*DirectInit=*/true);
    }
    break;
  }
  case InitKind::CXXBraced: {
    // Parse C++0x braced-init-list.
    Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);

    InitializerScopeRAII InitScope(*this, D, ThisDecl);

    PreferredType.enterVariableInit(Tok.getLocation(), ThisDecl);
    ExprResult Init(ParseBraceInitializer());

    InitScope.pop();

    if (Init.isInvalid()) {
      Actions.ActOnInitializerError(ThisDecl);
    } else
      Actions.AddInitializerToDecl(ThisDecl, Init.get(), /*DirectInit=*/true);
    break;
  }
  case InitKind::Uninitialized: {
    Actions.ActOnUninitializedDecl(ThisDecl);
    break;
  }
  }

  Actions.FinalizeDeclaration(ThisDecl);
  return OuterDecl ? OuterDecl : ThisDecl;
}

/// ParseSpecifierQualifierList
///        specifier-qualifier-list:
///          type-specifier specifier-qualifier-list[opt]
///          type-qualifier specifier-qualifier-list[opt]
/// [GNU]    attributes     specifier-qualifier-list[opt]
///
void Parser::ParseSpecifierQualifierList(
    DeclSpec &DS, ImplicitTypenameContext AllowImplicitTypename,
    AccessSpecifier AS, DeclSpecContext DSC) {
  /// specifier-qualifier-list is a subset of declaration-specifiers.  Just
  /// parse declaration-specifiers and complain about extra stuff.
  /// TODO: diagnose attribute-specifiers and alignment-specifiers.
  ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS, DSC, nullptr,
                             AllowImplicitTypename);

  // Validate declspec for type-name.
  unsigned Specs = DS.getParsedSpecifiers();
  if (isTypeSpecifier(DSC) && !DS.hasTypeSpecifier()) {
    Diag(Tok, diag::err_expected_type);
    DS.SetTypeSpecError();
  } else if (Specs == DeclSpec::PQ_None && !DS.hasAttributes()) {
    Diag(Tok, diag::err_typename_requires_specqual);
    if (!DS.hasTypeSpecifier())
      DS.SetTypeSpecError();
  }

  // Issue diagnostic and remove storage class if present.
  if (Specs & DeclSpec::PQ_StorageClassSpecifier) {
    if (DS.getStorageClassSpecLoc().isValid())
      Diag(DS.getStorageClassSpecLoc(),diag::err_typename_invalid_storageclass);
    else
      Diag(DS.getThreadStorageClassSpecLoc(),
           diag::err_typename_invalid_storageclass);
    DS.ClearStorageClassSpecs();
  }

  // Issue diagnostic and remove function specifier if present.
  if (Specs & DeclSpec::PQ_FunctionSpecifier) {
    if (DS.isInlineSpecified())
      Diag(DS.getInlineSpecLoc(), diag::err_typename_invalid_functionspec);
    if (DS.isVirtualSpecified())
      Diag(DS.getVirtualSpecLoc(), diag::err_typename_invalid_functionspec);
    if (DS.hasExplicitSpecifier())
      Diag(DS.getExplicitSpecLoc(), diag::err_typename_invalid_functionspec);
    if (DS.isNoreturnSpecified())
      Diag(DS.getNoreturnSpecLoc(), diag::err_typename_invalid_functionspec);
    DS.ClearFunctionSpecs();
  }

  // Issue diagnostic and remove constexpr specifier if present.
  if (DS.hasConstexprSpecifier() && DSC != DeclSpecContext::DSC_condition) {
    Diag(DS.getConstexprSpecLoc(), diag::err_typename_invalid_constexpr)
        << static_cast<int>(DS.getConstexprSpecifier());
    DS.ClearConstexprSpec();
  }
}

/// isValidAfterIdentifierInDeclaratorAfterDeclSpec - Return true if the
/// specified token is valid after the identifier in a declarator which
/// immediately follows the declspec.  For example, these things are valid:
///
///      int x   [             4];         // direct-declarator
///      int x   (             int y);     // direct-declarator
///  int(int x   )                         // direct-declarator
///      int x   ;                         // simple-declaration
///      int x   =             17;         // init-declarator-list
///      int x   ,             y;          // init-declarator-list
///      int x   __asm__       ("foo");    // init-declarator-list
///      int x   :             4;          // struct-declarator
///      int x   {             5};         // C++'0x unified initializers
///
/// This is not, because 'x' does not immediately follow the declspec (though
/// ')' happens to be valid anyway).
///    int (x)
///
static bool isValidAfterIdentifierInDeclarator(const Token &T) {
  return T.isOneOf(tok::l_square, tok::l_paren, tok::r_paren, tok::semi,
                   tok::comma, tok::equal, tok::kw_asm, tok::l_brace,
                   tok::colon);
}

/// ParseImplicitInt - This method is called when we have an non-typename
/// identifier in a declspec (which normally terminates the decl spec) when
/// the declspec has no type specifier.  In this case, the declspec is either
/// malformed or is "implicit int" (in K&R and C89).
///
/// This method handles diagnosing this prettily and returns false if the
/// declspec is done being processed.  If it recovers and thinks there may be
/// other pieces of declspec after it, it returns true.
///
bool Parser::ParseImplicitInt(DeclSpec &DS, CXXScopeSpec *SS,
                              const ParsedTemplateInfo &TemplateInfo,
                              AccessSpecifier AS, DeclSpecContext DSC,
                              ParsedAttributes &Attrs) {
  assert(Tok.is(tok::identifier) && "should have identifier");

  SourceLocation Loc = Tok.getLocation();
  // If we see an identifier that is not a type name, we normally would
  // parse it as the identifier being declared.  However, when a typename
  // is typo'd or the definition is not included, this will incorrectly
  // parse the typename as the identifier name and fall over misparsing
  // later parts of the diagnostic.
  //
  // As such, we try to do some look-ahead in cases where this would
  // otherwise be an "implicit-int" case to see if this is invalid.  For
  // example: "static foo_t x = 4;"  In this case, if we parsed foo_t as
  // an identifier with implicit int, we'd get a parse error because the
  // next token is obviously invalid for a type.  Parse these as a case
  // with an invalid type specifier.
  assert(!DS.hasTypeSpecifier() && "Type specifier checked above");

  // Since we know that this either implicit int (which is rare) or an
  // error, do lookahead to try to do better recovery. This never applies
  // within a type specifier. Outside of C++, we allow this even if the
  // language doesn't "officially" support implicit int -- we support
  // implicit int as an extension in some language modes.
  if (!isTypeSpecifier(DSC) && getLangOpts().isImplicitIntAllowed() &&
      isValidAfterIdentifierInDeclarator(NextToken())) {
    // If this token is valid for implicit int, e.g. "static x = 4", then
    // we just avoid eating the identifier, so it will be parsed as the
    // identifier in the declarator.
    return false;
  }

  // Early exit as Sema has a dedicated missing_actual_pipe_type diagnostic
  // for incomplete declarations such as `pipe p`.
  if (getLangOpts().OpenCLCPlusPlus && DS.isTypeSpecPipe())
    return false;

  if (getLangOpts().CPlusPlus &&
      DS.getStorageClassSpec() == DeclSpec::SCS_auto) {
    // Don't require a type specifier if we have the 'auto' storage class
    // specifier in C++98 -- we'll promote it to a type specifier.
    if (SS)
      AnnotateScopeToken(*SS, /*IsNewAnnotation*/false);
    return false;
  }

  if (getLangOpts().CPlusPlus && (!SS || SS->isEmpty()) &&
      getLangOpts().MSVCCompat) {
    // Lookup of an unqualified type name has failed in MSVC compatibility mode.
    // Give Sema a chance to recover if we are in a template with dependent base
    // classes.
    if (ParsedType T = Actions.ActOnMSVCUnknownTypeName(
            *Tok.getIdentifierInfo(), Tok.getLocation(),
            DSC == DeclSpecContext::DSC_template_type_arg)) {
      const char *PrevSpec;
      unsigned DiagID;
      DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec, DiagID, T,
                         Actions.getASTContext().getPrintingPolicy());
      DS.SetRangeEnd(Tok.getLocation());
      ConsumeToken();
      return false;
    }
  }

  // Otherwise, if we don't consume this token, we are going to emit an
  // error anyway.  Try to recover from various common problems.  Check
  // to see if this was a reference to a tag name without a tag specified.
  // This is a common problem in C (saying 'foo' instead of 'struct foo').
  //
  // C++ doesn't need this, and isTagName doesn't take SS.
  if (SS == nullptr) {
    const char *TagName = nullptr, *FixitTagName = nullptr;
    tok::TokenKind TagKind = tok::unknown;

    switch (Actions.isTagName(*Tok.getIdentifierInfo(), getCurScope())) {
      default: break;
      case DeclSpec::TST_enum:
        TagName="enum"  ; FixitTagName = "enum "  ; TagKind=tok::kw_enum ;break;
      case DeclSpec::TST_union:
        TagName="union" ; FixitTagName = "union " ;TagKind=tok::kw_union ;break;
      case DeclSpec::TST_struct:
        TagName="struct"; FixitTagName = "struct ";TagKind=tok::kw_struct;break;
      case DeclSpec::TST_interface:
        TagName="__interface"; FixitTagName = "__interface ";
        TagKind=tok::kw___interface;break;
      case DeclSpec::TST_class:
        TagName="class" ; FixitTagName = "class " ;TagKind=tok::kw_class ;break;
    }

    if (TagName) {
      IdentifierInfo *TokenName = Tok.getIdentifierInfo();
      LookupResult R(Actions, TokenName, SourceLocation(),
                     Sema::LookupOrdinaryName);

      Diag(Loc, diag::err_use_of_tag_name_without_tag)
        << TokenName << TagName << getLangOpts().CPlusPlus
        << FixItHint::CreateInsertion(Tok.getLocation(), FixitTagName);

      if (Actions.LookupParsedName(R, getCurScope(), SS)) {
        for (LookupResult::iterator I = R.begin(), IEnd = R.end();
             I != IEnd; ++I)
          Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
            << TokenName << TagName;
      }

      // Parse this as a tag as if the missing tag were present.
      if (TagKind == tok::kw_enum)
        ParseEnumSpecifier(Loc, DS, TemplateInfo, AS,
                           DeclSpecContext::DSC_normal);
      else
        ParseClassSpecifier(TagKind, Loc, DS, TemplateInfo, AS,
                            /*EnteringContext*/ false,
                            DeclSpecContext::DSC_normal, Attrs);
      return true;
    }
  }

  // Determine whether this identifier could plausibly be the name of something
  // being declared (with a missing type).
  if (!isTypeSpecifier(DSC) && (!SS || DSC == DeclSpecContext::DSC_top_level ||
                                DSC == DeclSpecContext::DSC_class)) {
    // Look ahead to the next token to try to figure out what this declaration
    // was supposed to be.
    switch (NextToken().getKind()) {
    case tok::l_paren: {
      // static x(4); // 'x' is not a type
      // x(int n);    // 'x' is not a type
      // x (*p)[];    // 'x' is a type
      //
      // Since we're in an error case, we can afford to perform a tentative
      // parse to determine which case we're in.
      TentativeParsingAction PA(*this);
      ConsumeToken();
      TPResult TPR = TryParseDeclarator(/*mayBeAbstract*/false);
      PA.Revert();

      if (TPR != TPResult::False) {
        // The identifier is followed by a parenthesized declarator.
        // It's supposed to be a type.
        break;
      }

      // If we're in a context where we could be declaring a constructor,
      // check whether this is a constructor declaration with a bogus name.
      if (DSC == DeclSpecContext::DSC_class ||
          (DSC == DeclSpecContext::DSC_top_level && SS)) {
        IdentifierInfo *II = Tok.getIdentifierInfo();
        if (Actions.isCurrentClassNameTypo(II, SS)) {
          Diag(Loc, diag::err_constructor_bad_name)
            << Tok.getIdentifierInfo() << II
            << FixItHint::CreateReplacement(Tok.getLocation(), II->getName());
          Tok.setIdentifierInfo(II);
        }
      }
      // Fall through.
      [[fallthrough]];
    }
    case tok::comma:
    case tok::equal:
    case tok::kw_asm:
    case tok::l_brace:
    case tok::l_square:
    case tok::semi:
      // This looks like a variable or function declaration. The type is
      // probably missing. We're done parsing decl-specifiers.
      // But only if we are not in a function prototype scope.
      if (getCurScope()->isFunctionPrototypeScope())
        break;
      if (SS)
        AnnotateScopeToken(*SS, /*IsNewAnnotation*/false);
      return false;

    default:
      // This is probably supposed to be a type. This includes cases like:
      //   int f(itn);
      //   struct S { unsigned : 4; };
      break;
    }
  }

  // This is almost certainly an invalid type name. Let Sema emit a diagnostic
  // and attempt to recover.
  ParsedType T;
  IdentifierInfo *II = Tok.getIdentifierInfo();
  bool IsTemplateName = getLangOpts().CPlusPlus && NextToken().is(tok::less);
  Actions.DiagnoseUnknownTypeName(II, Loc, getCurScope(), SS, T,
                                  IsTemplateName);
  if (T) {
    // The action has suggested that the type T could be used. Set that as
    // the type in the declaration specifiers, consume the would-be type
    // name token, and we're done.
    const char *PrevSpec;
    unsigned DiagID;
    DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec, DiagID, T,
                       Actions.getASTContext().getPrintingPolicy());
    DS.SetRangeEnd(Tok.getLocation());
    ConsumeToken();
    // There may be other declaration specifiers after this.
    return true;
  } else if (II != Tok.getIdentifierInfo()) {
    // If no type was suggested, the correction is to a keyword
    Tok.setKind(II->getTokenID());
    // There may be other declaration specifiers after this.
    return true;
  }

  // Otherwise, the action had no suggestion for us.  Mark this as an error.
  DS.SetTypeSpecError();
  DS.SetRangeEnd(Tok.getLocation());
  ConsumeToken();

  // Eat any following template arguments.
  if (IsTemplateName) {
    SourceLocation LAngle, RAngle;
    TemplateArgList Args;
    ParseTemplateIdAfterTemplateName(true, LAngle, Args, RAngle);
  }

  // TODO: Could inject an invalid typedef decl in an enclosing scope to
  // avoid rippling error messages on subsequent uses of the same type,
  // could be useful if #include was forgotten.
  return true;
}

/// Determine the declaration specifier context from the declarator
/// context.
///
/// \param Context the declarator context, which is one of the
/// DeclaratorContext enumerator values.
Parser::DeclSpecContext
Parser::getDeclSpecContextFromDeclaratorContext(DeclaratorContext Context) {
  switch (Context) {
  case DeclaratorContext::Member:
    return DeclSpecContext::DSC_class;
  case DeclaratorContext::File:
    return DeclSpecContext::DSC_top_level;
  case DeclaratorContext::TemplateParam:
    return DeclSpecContext::DSC_template_param;
  case DeclaratorContext::TemplateArg:
    return DeclSpecContext::DSC_template_arg;
  case DeclaratorContext::TemplateTypeArg:
    return DeclSpecContext::DSC_template_type_arg;
  case DeclaratorContext::TrailingReturn:
  case DeclaratorContext::TrailingReturnVar:
    return DeclSpecContext::DSC_trailing;
  case DeclaratorContext::AliasDecl:
  case DeclaratorContext::AliasTemplate:
    return DeclSpecContext::DSC_alias_declaration;
  case DeclaratorContext::Association:
    return DeclSpecContext::DSC_association;
  case DeclaratorContext::TypeName:
    return DeclSpecContext::DSC_type_specifier;
  case DeclaratorContext::Condition:
    return DeclSpecContext::DSC_condition;
  case DeclaratorContext::ConversionId:
    return DeclSpecContext::DSC_conv_operator;
  case DeclaratorContext::Prototype:
  case DeclaratorContext::ObjCResult:
  case DeclaratorContext::ObjCParameter:
  case DeclaratorContext::KNRTypeList:
  case DeclaratorContext::FunctionalCast:
  case DeclaratorContext::Block:
  case DeclaratorContext::ForInit:
  case DeclaratorContext::SelectionInit:
  case DeclaratorContext::CXXNew:
  case DeclaratorContext::CXXCatch:
  case DeclaratorContext::ObjCCatch:
  case DeclaratorContext::BlockLiteral:
  case DeclaratorContext::LambdaExpr:
  case DeclaratorContext::LambdaExprParameter:
  case DeclaratorContext::RequiresExpr:
    return DeclSpecContext::DSC_normal;
  }

  llvm_unreachable("Missing DeclaratorContext case");
}

/// ParseAlignArgument - Parse the argument to an alignment-specifier.
///
/// [C11]   type-id
/// [C11]   constant-expression
/// [C++0x] type-id ...[opt]
/// [C++0x] assignment-expression ...[opt]
ExprResult Parser::ParseAlignArgument(StringRef KWName, SourceLocation Start,
                                      SourceLocation &EllipsisLoc, bool &IsType,
                                      ParsedType &TypeResult) {
  ExprResult ER;
  if (isTypeIdInParens()) {
    SourceLocation TypeLoc = Tok.getLocation();
    ParsedType Ty = ParseTypeName().get();
    SourceRange TypeRange(Start, Tok.getLocation());
    if (Actions.ActOnAlignasTypeArgument(KWName, Ty, TypeLoc, TypeRange))
      return ExprError();
    TypeResult = Ty;
    IsType = true;
  } else {
    ER = ParseConstantExpression();
    IsType = false;
  }

  if (getLangOpts().CPlusPlus11)
    TryConsumeToken(tok::ellipsis, EllipsisLoc);

  return ER;
}

/// ParseAlignmentSpecifier - Parse an alignment-specifier, and add the
/// attribute to Attrs.
///
/// alignment-specifier:
/// [C11]   '_Alignas' '(' type-id ')'
/// [C11]   '_Alignas' '(' constant-expression ')'
/// [C++11] 'alignas' '(' type-id ...[opt] ')'
/// [C++11] 'alignas' '(' assignment-expression ...[opt] ')'
void Parser::ParseAlignmentSpecifier(ParsedAttributes &Attrs,
                                     SourceLocation *EndLoc) {
  assert(Tok.isOneOf(tok::kw_alignas, tok::kw__Alignas) &&
         "Not an alignment-specifier!");
  Token KWTok = Tok;
  IdentifierInfo *KWName = KWTok.getIdentifierInfo();
  auto Kind = KWTok.getKind();
  SourceLocation KWLoc = ConsumeToken();

  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.expectAndConsume())
    return;

  bool IsType;
  ParsedType TypeResult;
  SourceLocation EllipsisLoc;
  ExprResult ArgExpr =
      ParseAlignArgument(PP.getSpelling(KWTok), T.getOpenLocation(),
                         EllipsisLoc, IsType, TypeResult);
  if (ArgExpr.isInvalid()) {
    T.skipToEnd();
    return;
  }

  T.consumeClose();
  if (EndLoc)
    *EndLoc = T.getCloseLocation();

  if (IsType) {
    Attrs.addNewTypeAttr(KWName, KWLoc, nullptr, KWLoc, TypeResult, Kind,
                         EllipsisLoc);
  } else {
    ArgsVector ArgExprs;
    ArgExprs.push_back(ArgExpr.get());
    Attrs.addNew(KWName, KWLoc, nullptr, KWLoc, ArgExprs.data(), 1, Kind,
                 EllipsisLoc);
  }
}

ExprResult Parser::ParseExtIntegerArgument() {
  assert(Tok.isOneOf(tok::kw__ExtInt, tok::kw__BitInt) &&
         "Not an extended int type");
  ConsumeToken();

  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.expectAndConsume())
    return ExprError();

  ExprResult ER = ParseConstantExpression();
  if (ER.isInvalid()) {
    T.skipToEnd();
    return ExprError();
  }

  if(T.consumeClose())
    return ExprError();
  return ER;
}

/// Determine whether we're looking at something that might be a declarator
/// in a simple-declaration. If it can't possibly be a declarator, maybe
/// diagnose a missing semicolon after a prior tag definition in the decl
/// specifier.
///
/// \return \c true if an error occurred and this can't be any kind of
/// declaration.
bool
Parser::DiagnoseMissingSemiAfterTagDefinition(DeclSpec &DS, AccessSpecifier AS,
                                              DeclSpecContext DSContext,
                                              LateParsedAttrList *LateAttrs) {
  assert(DS.hasTagDefinition() && "shouldn't call this");

  bool EnteringContext = (DSContext == DeclSpecContext::DSC_class ||
                          DSContext == DeclSpecContext::DSC_top_level);

  if (getLangOpts().CPlusPlus &&
      Tok.isOneOf(tok::identifier, tok::coloncolon, tok::kw_decltype,
                  tok::annot_template_id) &&
      TryAnnotateCXXScopeToken(EnteringContext)) {
    SkipMalformedDecl();
    return true;
  }

  bool HasScope = Tok.is(tok::annot_cxxscope);
  // Make a copy in case GetLookAheadToken invalidates the result of NextToken.
  Token AfterScope = HasScope ? NextToken() : Tok;

  // Determine whether the following tokens could possibly be a
  // declarator.
  bool MightBeDeclarator = true;
  if (Tok.isOneOf(tok::kw_typename, tok::annot_typename)) {
    // A declarator-id can't start with 'typename'.
    MightBeDeclarator = false;
  } else if (AfterScope.is(tok::annot_template_id)) {
    // If we have a type expressed as a template-id, this cannot be a
    // declarator-id (such a type cannot be redeclared in a simple-declaration).
    TemplateIdAnnotation *Annot =
        static_cast<TemplateIdAnnotation *>(AfterScope.getAnnotationValue());
    if (Annot->Kind == TNK_Type_template)
      MightBeDeclarator = false;
  } else if (AfterScope.is(tok::identifier)) {
    const Token &Next = HasScope ? GetLookAheadToken(2) : NextToken();

    // These tokens cannot come after the declarator-id in a
    // simple-declaration, and are likely to come after a type-specifier.
    if (Next.isOneOf(tok::star, tok::amp, tok::ampamp, tok::identifier,
                     tok::annot_cxxscope, tok::coloncolon)) {
      // Missing a semicolon.
      MightBeDeclarator = false;
    } else if (HasScope) {
      // If the declarator-id has a scope specifier, it must redeclare a
      // previously-declared entity. If that's a type (and this is not a
      // typedef), that's an error.
      CXXScopeSpec SS;
      Actions.RestoreNestedNameSpecifierAnnotation(
          Tok.getAnnotationValue(), Tok.getAnnotationRange(), SS);
      IdentifierInfo *Name = AfterScope.getIdentifierInfo();
      Sema::NameClassification Classification = Actions.ClassifyName(
          getCurScope(), SS, Name, AfterScope.getLocation(), Next,
          /*CCC=*/nullptr);
      switch (Classification.getKind()) {
      case Sema::NC_Error:
        SkipMalformedDecl();
        return true;

      case Sema::NC_Keyword:
        llvm_unreachable("typo correction is not possible here");

      case Sema::NC_Type:
      case Sema::NC_TypeTemplate:
      case Sema::NC_UndeclaredNonType:
      case Sema::NC_UndeclaredTemplate:
        // Not a previously-declared non-type entity.
        MightBeDeclarator = false;
        break;

      case Sema::NC_Unknown:
      case Sema::NC_NonType:
      case Sema::NC_DependentNonType:
      case Sema::NC_OverloadSet:
      case Sema::NC_VarTemplate:
      case Sema::NC_FunctionTemplate:
      case Sema::NC_Concept:
        // Might be a redeclaration of a prior entity.
        break;
      }
    }
  }

  if (MightBeDeclarator)
    return false;

  const PrintingPolicy &PPol = Actions.getASTContext().getPrintingPolicy();
  Diag(PP.getLocForEndOfToken(DS.getRepAsDecl()->getEndLoc()),
       diag::err_expected_after)
      << DeclSpec::getSpecifierName(DS.getTypeSpecType(), PPol) << tok::semi;

  // Try to recover from the typo, by dropping the tag definition and parsing
  // the problematic tokens as a type.
  //
  // FIXME: Split the DeclSpec into pieces for the standalone
  // declaration and pieces for the following declaration, instead
  // of assuming that all the other pieces attach to new declaration,
  // and call ParsedFreeStandingDeclSpec as appropriate.
  DS.ClearTypeSpecType();
  ParsedTemplateInfo NotATemplate;
  ParseDeclarationSpecifiers(DS, NotATemplate, AS, DSContext, LateAttrs);
  return false;
}

// Choose the apprpriate diagnostic error for why fixed point types are
// disabled, set the previous specifier, and mark as invalid.
static void SetupFixedPointError(const LangOptions &LangOpts,
                                 const char *&PrevSpec, unsigned &DiagID,
                                 bool &isInvalid) {
  assert(!LangOpts.FixedPoint);
  DiagID = diag::err_fixed_point_not_enabled;
  PrevSpec = "";  // Not used by diagnostic
  isInvalid = true;
}

/// ParseDeclarationSpecifiers
///       declaration-specifiers: [C99 6.7]
///         storage-class-specifier declaration-specifiers[opt]
///         type-specifier declaration-specifiers[opt]
/// [C99]   function-specifier declaration-specifiers[opt]
/// [C11]   alignment-specifier declaration-specifiers[opt]
/// [GNU]   attributes declaration-specifiers[opt]
/// [Clang] '__module_private__' declaration-specifiers[opt]
/// [ObjC1] '__kindof' declaration-specifiers[opt]
///
///       storage-class-specifier: [C99 6.7.1]
///         'typedef'
///         'extern'
///         'static'
///         'auto'
///         'register'
/// [C++]   'mutable'
/// [C++11] 'thread_local'
/// [C11]   '_Thread_local'
/// [GNU]   '__thread'
///       function-specifier: [C99 6.7.4]
/// [C99]   'inline'
/// [C++]   'virtual'
/// [C++]   'explicit'
/// [OpenCL] '__kernel'
///       'friend': [C++ dcl.friend]
///       'constexpr': [C++0x dcl.constexpr]
void Parser::ParseDeclarationSpecifiers(
    DeclSpec &DS, const ParsedTemplateInfo &TemplateInfo, AccessSpecifier AS,
    DeclSpecContext DSContext, LateParsedAttrList *LateAttrs,
    ImplicitTypenameContext AllowImplicitTypename) {
  if (DS.getSourceRange().isInvalid()) {
    // Start the range at the current token but make the end of the range
    // invalid.  This will make the entire range invalid unless we successfully
    // consume a token.
    DS.SetRangeStart(Tok.getLocation());
    DS.SetRangeEnd(SourceLocation());
  }

  // If we are in a operator context, convert it back into a type specifier
  // context for better error handling later on.
  if (DSContext == DeclSpecContext::DSC_conv_operator) {
    // No implicit typename here.
    AllowImplicitTypename = ImplicitTypenameContext::No;
    DSContext = DeclSpecContext::DSC_type_specifier;
  }

  bool EnteringContext = (DSContext == DeclSpecContext::DSC_class ||
                          DSContext == DeclSpecContext::DSC_top_level);
  bool AttrsLastTime = false;
  ParsedAttributes attrs(AttrFactory);
  // We use Sema's policy to get bool macros right.
  PrintingPolicy Policy = Actions.getPrintingPolicy();
  while (true) {
    bool isInvalid = false;
    bool isStorageClass = false;
    const char *PrevSpec = nullptr;
    unsigned DiagID = 0;

    // This value needs to be set to the location of the last token if the last
    // token of the specifier is already consumed.
    SourceLocation ConsumedEnd;

    // HACK: MSVC doesn't consider _Atomic to be a keyword and its STL
    // implementation for VS2013 uses _Atomic as an identifier for one of the
    // classes in <atomic>.
    //
    // A typedef declaration containing _Atomic<...> is among the places where
    // the class is used.  If we are currently parsing such a declaration, treat
    // the token as an identifier.
    if (getLangOpts().MSVCCompat && Tok.is(tok::kw__Atomic) &&
        DS.getStorageClassSpec() == clang::DeclSpec::SCS_typedef &&
        !DS.hasTypeSpecifier() && GetLookAheadToken(1).is(tok::less))
      Tok.setKind(tok::identifier);

    SourceLocation Loc = Tok.getLocation();

    // Helper for image types in OpenCL.
    auto handleOpenCLImageKW = [&] (StringRef Ext, TypeSpecifierType ImageTypeSpec) {
      // Check if the image type is supported and otherwise turn the keyword into an identifier
      // because image types from extensions are not reserved identifiers.
      if (!StringRef(Ext).empty() && !getActions().getOpenCLOptions().isSupported(Ext, getLangOpts())) {
        Tok.getIdentifierInfo()->revertTokenIDToIdentifier();
        Tok.setKind(tok::identifier);
        return false;
      }
      isInvalid = DS.SetTypeSpecType(ImageTypeSpec, Loc, PrevSpec, DiagID, Policy);
      return true;
    };

    // Turn off usual access checking for template specializations and
    // instantiations.
    bool IsTemplateSpecOrInst =
        (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
         TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);

    switch (Tok.getKind()) {
    default:
      if (Tok.isRegularKeywordAttribute())
        goto Attribute;

    DoneWithDeclSpec:
      if (!AttrsLastTime)
        ProhibitAttributes(attrs);
      else {
        // Reject C++11 / C2x attributes that aren't type attributes.
        for (const ParsedAttr &PA : attrs) {
          if (!PA.isCXX11Attribute() && !PA.isC2xAttribute() &&
              !PA.isRegularKeywordAttribute())
            continue;
          if (PA.getKind() == ParsedAttr::UnknownAttribute)
            // We will warn about the unknown attribute elsewhere (in
            // SemaDeclAttr.cpp)
            continue;
          // GCC ignores this attribute when placed on the DeclSpec in [[]]
          // syntax, so we do the same.
          if (PA.getKind() == ParsedAttr::AT_VectorSize) {
            Diag(PA.getLoc(), diag::warn_attribute_ignored) << PA;
            PA.setInvalid();
            continue;
          }
          // We reject AT_LifetimeBound and AT_AnyX86NoCfCheck, even though they
          // are type attributes, because we historically haven't allowed these
          // to be used as type attributes in C++11 / C2x syntax.
          if (PA.isTypeAttr() && PA.getKind() != ParsedAttr::AT_LifetimeBound &&
              PA.getKind() != ParsedAttr::AT_AnyX86NoCfCheck)
            continue;
          Diag(PA.getLoc(), diag::err_attribute_not_type_attr)
              << PA << PA.isRegularKeywordAttribute();
          PA.setInvalid();
        }

        DS.takeAttributesFrom(attrs);
      }

      // If this is not a declaration specifier token, we're done reading decl
      // specifiers.  First verify that DeclSpec's are consistent.
      DS.Finish(Actions, Policy);
      return;

    case tok::l_square:
    case tok::kw_alignas:
      if (!isAllowedCXX11AttributeSpecifier())
        goto DoneWithDeclSpec;

    Attribute:
      ProhibitAttributes(attrs);
      // FIXME: It would be good to recover by accepting the attributes,
      //        but attempting to do that now would cause serious
      //        madness in terms of diagnostics.
      attrs.clear();
      attrs.Range = SourceRange();

      ParseCXX11Attributes(attrs);
      AttrsLastTime = true;
      continue;

    case tok::code_completion: {
      Sema::ParserCompletionContext CCC = Sema::PCC_Namespace;
      if (DS.hasTypeSpecifier()) {
        bool AllowNonIdentifiers
          = (getCurScope()->getFlags() & (Scope::ControlScope |
                                          Scope::BlockScope |
                                          Scope::TemplateParamScope |
                                          Scope::FunctionPrototypeScope |
                                          Scope::AtCatchScope)) == 0;
        bool AllowNestedNameSpecifiers
          = DSContext == DeclSpecContext::DSC_top_level ||
            (DSContext == DeclSpecContext::DSC_class && DS.isFriendSpecified());

        cutOffParsing();
        Actions.CodeCompleteDeclSpec(getCurScope(), DS,
                                     AllowNonIdentifiers,
                                     AllowNestedNameSpecifiers);
        return;
      }

      // Class context can appear inside a function/block, so prioritise that.
      if (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate)
        CCC = DSContext == DeclSpecContext::DSC_class ? Sema::PCC_MemberTemplate
                                                      : Sema::PCC_Template;
      else if (DSContext == DeclSpecContext::DSC_class)
        CCC = Sema::PCC_Class;
      else if (getCurScope()->getFnParent() || getCurScope()->getBlockParent())
        CCC = Sema::PCC_LocalDeclarationSpecifiers;
      else if (CurParsedObjCImpl)
        CCC = Sema::PCC_ObjCImplementation;

      cutOffParsing();
      Actions.CodeCompleteOrdinaryName(getCurScope(), CCC);
      return;
    }

    case tok::coloncolon: // ::foo::bar
      // C++ scope specifier.  Annotate and loop, or bail out on error.
      if (TryAnnotateCXXScopeToken(EnteringContext)) {
        if (!DS.hasTypeSpecifier())
          DS.SetTypeSpecError();
        goto DoneWithDeclSpec;
      }
      if (Tok.is(tok::coloncolon)) // ::new or ::delete
        goto DoneWithDeclSpec;
      continue;

    case tok::annot_cxxscope: {
      if (DS.hasTypeSpecifier() || DS.isTypeAltiVecVector())
        goto DoneWithDeclSpec;

      CXXScopeSpec SS;
      if (TemplateInfo.TemplateParams)
        SS.setTemplateParamLists(*TemplateInfo.TemplateParams);
      Actions.RestoreNestedNameSpecifierAnnotation(Tok.getAnnotationValue(),
                                                   Tok.getAnnotationRange(),
                                                   SS);

      // We are looking for a qualified typename.
      Token Next = NextToken();