xref: /freebsd/contrib/llvm-project/clang/lib/Parse/ParseDecl.cpp (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)

//===--- 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/Basic/TokenKinds.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/SemaCUDA.h"
#include "clang/Sema/SemaCodeCompletion.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "clang/Sema/SemaObjC.h"
#include "clang/Sema/SemaOpenMP.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(DeclaratorInfo);
}

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

/// returns true iff attribute is annotated with `LateAttrParseExperimentalExt`
/// in `Attr.td`.
static bool IsAttributeLateParsedExperimentalExt(const IdentifierInfo &II) {
#define CLANG_ATTR_LATE_PARSED_EXPERIMENTAL_EXT_LIST
  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
      .Default(false);
#undef CLANG_ATTR_LATE_PARSED_EXPERIMENTAL_EXT_LIST
}

/// returns true iff attribute is annotated with `LateAttrParseStandard` in
/// `Attr.td`.
static bool IsAttributeLateParsedStandard(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.CodeCompletion().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;
      }

      bool LateParse = false;
      if (!LateAttrs)
        LateParse = false;
      else if (LateAttrs->lateAttrParseExperimentalExtOnly()) {
        // The caller requested that this attribute **only** be late
        // parsed for `LateAttrParseExperimentalExt` attributes. This will
        // only be late parsed if the experimental language option is enabled.
        LateParse = getLangOpts().ExperimentalLateParseAttributes &&
                    IsAttributeLateParsedExperimentalExt(*AttrName);
      } else {
        // The caller did not restrict late parsing to only
        // `LateAttrParseExperimentalExt` attributes so late parse
        // both `LateAttrParseStandard` and `LateAttrParseExperimentalExt`
        // attributes.
        LateParse = IsAttributeLateParsedExperimentalExt(*AttrName) ||
                    IsAttributeLateParsedStandard(*AttrName);
      }

      // Handle "parameterized" attributes
      if (!LateParse) {
        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 an identifier argument.
static ParsedAttributeArgumentsProperties
attributeStringLiteralListArg(const llvm::Triple &T, const IdentifierInfo &II) {
#define CLANG_ATTR_STRING_LITERAL_ARG_LIST
  return llvm::StringSwitch<uint32_t>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
      .Default(0);
#undef CLANG_ATTR_STRING_LITERAL_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 takes identifier arguments.
static bool attributeHasStrictIdentifierArgs(const IdentifierInfo &II) {
#define CLANG_ATTR_STRICT_IDENTIFIER_ARG_AT_INDEX_LIST
  return (llvm::StringSwitch<uint64_t>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
              .Default(0)) != 0;
#undef CLANG_ATTR_STRICT_IDENTIFIER_ARG_AT_INDEX_LIST
}

/// Determine whether the given attribute takes an identifier argument at a
/// specific index
static bool attributeHasStrictIdentifierArgAtIndex(const IdentifierInfo &II,
                                                   size_t argIndex) {
#define CLANG_ATTR_STRICT_IDENTIFIER_ARG_AT_INDEX_LIST
  return (llvm::StringSwitch<uint64_t>(normalizeAttrName(II.getName()))
#include "clang/Parse/AttrParserStringSwitches.inc"
              .Default(0)) &
         (1ull << argIndex);
#undef CLANG_ATTR_STRICT_IDENTIFIER_ARG_AT_INDEX_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);
}

ExprResult
Parser::ParseUnevaluatedStringInAttribute(const IdentifierInfo &AttrName) {
  if (Tok.is(tok::l_paren)) {
    BalancedDelimiterTracker Paren(*this, tok::l_paren);
    Paren.consumeOpen();
    ExprResult Res = ParseUnevaluatedStringInAttribute(AttrName);
    Paren.consumeClose();
    return Res;
  }
  if (!isTokenStringLiteral()) {
    Diag(Tok.getLocation(), diag::err_expected_string_literal)
        << /*in attribute...*/ 4 << AttrName.getName();
    return ExprError();
  }
  return ParseUnevaluatedStringLiteralExpression();
}

bool Parser::ParseAttributeArgumentList(
    const IdentifierInfo &AttrName, SmallVectorImpl<Expr *> &Exprs,
    ParsedAttributeArgumentsProperties ArgsProperties) {
  bool SawError = false;
  unsigned Arg = 0;
  while (true) {
    ExprResult Expr;
    if (ArgsProperties.isStringLiteralArg(Arg)) {
      Expr = ParseUnevaluatedStringInAttribute(AttrName);
    } else if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
      Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
      Expr = ParseBraceInitializer();
    } else {
      Expr = ParseAssignmentExpression();
    }
    Expr = Actions.CorrectDelayedTyposInExpr(Expr);

    if (Tok.is(tok::ellipsis))
      Expr = Actions.ActOnPackExpansion(Expr.get(), ConsumeToken());
    else if (Tok.is(tok::code_completion)) {
      // There's nothing to suggest in here as we parsed a full expression.
      // Instead fail and propagate the error since caller might have something
      // the suggest, e.g. signature help in function call. Note that this is
      // performed before pushing the \p Expr, so that signature help can report
      // current argument correctly.
      SawError = true;
      cutOffParsing();
      break;
    }

    if (Expr.isInvalid()) {
      SawError = true;
      break;
    }

    if (Actions.DiagnoseUnexpandedParameterPack(Expr.get())) {
      SawError = true;
      break;
    }

    Exprs.push_back(Expr.get());

    if (Tok.isNot(tok::comma))
      break;
    // Move to the next argument, remember where the comma was.
    Token Comma = Tok;
    ConsumeToken();
    checkPotentialAngleBracketDelimiter(Comma);
    Arg++;
  }

  if (SawError) {
    // Ensure typos get diagnosed when errors were encountered while parsing the
    // expression list.
    for (auto &E : Exprs) {
      ExprResult Expr = Actions.CorrectDelayedTyposInExpr(E);
      if (Expr.isUsable())
        E = Expr.get();
    }
  }
  return SawError;
}

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 ||
               attributeHasStrictIdentifierArgs(*AttrName)) {
      // 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);

        if (Tok.is(tok::identifier) && attributeHasStrictIdentifierArgAtIndex(
                                           *AttrName, ArgExprs.size())) {
          ArgExprs.push_back(ParseIdentifierLoc());
          continue;
        }

        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,
              nullptr,
              Sema::ExpressionEvaluationContextRecord::EK_AttrArgument);

          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,
          nullptr,
          Sema::ExpressionEvaluationContextRecord::ExpressionKind::
              EK_AttrArgument);

      ExprVector ParsedExprs;
      ParsedAttributeArgumentsProperties ArgProperties =
          attributeStringLiteralListArg(getTargetInfo().getTriple(), *AttrName);
      if (ParseAttributeArgumentList(*AttrName, ParsedExprs, ArgProperties)) {
        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;
  } else if (AttrKind == ParsedAttr::AT_CountedBy ||
             AttrKind == ParsedAttr::AT_CountedByOrNull ||
             AttrKind == ParsedAttr::AT_SizedBy ||
             AttrKind == ParsedAttr::AT_SizedByOrNull) {
    ParseBoundsAttribute(*AttrName, AttrNameLoc, Attrs, ScopeName, ScopeLoc,
                         Form);
    return;
  } else if (AttrKind == ParsedAttr::AT_CXXAssume) {
    ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, EndLoc, 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;

  case ParsedAttr::AT_CXXAssume:
    ParseCXXAssumeAttributeArg(Attrs, AttrName, AttrNameLoc, EndLoc, 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.CodeCompletion().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;
  IdentifierLoc *EnvironmentLoc = nullptr;

  // 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) {
    // Disallow xrOS for availability attributes.
    if (Ident->getName().contains("xrOS") || Ident->getName().contains("xros"))
      Diag(Platform->Loc, diag::warn_availability_unknown_platform) << Ident;
    // Canonicalize platform name from "macosx" to "macos".
    else 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");
    Ident_environment = PP.getIdentifierInfo("environment");
  }

  // 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 (Keyword == Ident_environment) {
      if (EnvironmentLoc != nullptr) {
        Diag(KeywordLoc, diag::err_availability_redundant)
            << Keyword << SourceRange(EnvironmentLoc->Loc);
      }
    }

    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 (!isTokenStringLiteral()) {
        Diag(Tok, diag::err_expected_string_literal)
          << /*Source='availability attribute'*/2;
        SkipUntil(tok::r_paren, StopAtSemi);
        return;
      }
      if (Keyword == Ident_message) {
        MessageExpr = ParseUnevaluatedStringLiteralExpression();
        break;
      } else {
        ReplacementExpr = ParseUnevaluatedStringLiteralExpression();
        continue;
      }
    }
    if (Keyword == Ident_environment) {
      if (Tok.isNot(tok::identifier)) {
        Diag(Tok, diag::err_availability_expected_environment);
        SkipUntil(tok::r_paren, StopAtSemi);
        return;
      }
      EnvironmentLoc = ParseIdentifierLoc();
      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(), EnvironmentLoc);
}

/// 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 (!isTokenStringLiteral()) {
      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;
        ParseUnevaluatedStringLiteralExpression();
        continue;
      }
      Language = ParseUnevaluatedStringLiteralExpression();
    } else if (Keyword == Ident_USR) {
      if (HadUSR) {
        Diag(KeywordLoc, diag::err_external_source_symbol_duplicate_clause)
            << Keyword;
        ParseUnevaluatedStringLiteralExpression();
        continue;
      }
      USR = ParseUnevaluatedStringLiteralExpression();
    } else {
      assert(Keyword == Ident_defined_in && "Invalid clause keyword!");
      if (HadDefinedIn) {
        Diag(KeywordLoc, diag::err_external_source_symbol_duplicate_clause)
            << Keyword;
        ParseUnevaluatedStringLiteralExpression();
        continue;
      }
      DefinedInExpr = ParseUnevaluatedStringLiteralExpression();
    }
  } 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.isStandardAttributeSyntax())
      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.isStandardAttributeSyntax() || 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, TagUseKind TUK) {
  if (TUK == TagUseKind::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);
    return ParseDeclarationStartingWithTemplate(Context, DeclEnd, DeclAttrs);
  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);

  ParsedTemplateInfo TemplateInfo;
  DeclSpecContext DSContext = getDeclSpecContextFromDeclaratorContext(Context);
  ParseDeclarationSpecifiers(DS, TemplateInfo, 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);
    Actions.ActOnDefinedDeclarationSpecifier(TheDecl);
    DS.complete(TheDecl);
    if (AnonRecord) {
      Decl* decls[] = {AnonRecord, TheDecl};
      return Actions.BuildDeclaratorGroup(decls);
    }
    return Actions.ConvertDeclToDeclGroup(TheDecl);
  }

  if (DS.hasTagDefinition())
    Actions.ActOnDefinedDeclarationSpecifier(DS.getRepAsDecl());

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

  return ParseDeclGroup(DS, Context, DeclAttrs, TemplateInfo, &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,
                                              ParsedTemplateInfo &TemplateInfo,
                                              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);
  if (TemplateInfo.TemplateParams)
    D.setTemplateParameterLists(*TemplateInfo.TemplateParams);

  bool IsTemplateSpecOrInst =
      (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
       TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
  SuppressAccessChecks SAC(*this, IsTemplateSpecOrInst);

  ParseDeclarator(D);

  if (IsTemplateSpecOrInst)
    SAC.done();

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

  if (getLangOpts().HLSL)
    MaybeParseHLSLAnnotations(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.CodeCompletion().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)) {
          // C++23 [dcl.typedef] p1:
          //   The typedef specifier shall not be [...], and it shall not be
          //   used in the decl-specifier-seq of a parameter-declaration nor in
          //   the decl-specifier-seq of a function-definition.
          if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
            // If the user intended to write 'typename', we should have already
            // suggested adding it elsewhere. In any case, recover by ignoring
            // 'typedef' and suggest removing it.
            Diag(DS.getStorageClassSpecLoc(),
                 diag::err_function_declared_typedef)
                << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
            DS.ClearStorageClassSpecs();
          }
          Decl *TheDecl = nullptr;

          if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
            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) << 0;
              TheDecl = ParseFunctionDefinition(D, ParsedTemplateInfo(),
                                                &LateParsedAttrs);
            } 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));

              TheDecl = ParseFunctionDefinition(
                  D,
                  ParsedTemplateInfo(&FakedParamLists,
                                     /*isSpecialization=*/true,
                                     /*lastParameterListWasEmpty=*/true),
                  &LateParsedAttrs);
            }
          } else {
            TheDecl =
                ParseFunctionDefinition(D, TemplateInfo, &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;
      EnterExpressionEvaluationContext ForRangeInitContext(
          Actions, Sema::ExpressionEvaluationContext::PotentiallyEvaluated,
          /*LambdaContextDecl=*/nullptr,
          Sema::ExpressionEvaluationContextRecord::EK_Other,
          getLangOpts().CPlusPlus23);

      // P2718R0 - Lifetime extension in range-based for loops.
      if (getLangOpts().CPlusPlus23) {
        auto &LastRecord = Actions.ExprEvalContexts.back();
        LastRecord.InLifetimeExtendingContext = true;
      }

      if (getLangOpts().OpenMP)
        Actions.OpenMP().startOpenMPCXXRangeFor();
      if (Tok.is(tok::l_brace))
        FRI->RangeExpr = ParseBraceInitializer();
      else
        FRI->RangeExpr = ParseExpression();

      // Before c++23, ForRangeLifetimeExtendTemps should be empty.
      assert(
          getLangOpts().CPlusPlus23 ||
          Actions.ExprEvalContexts.back().ForRangeLifetimeExtendTemps.empty());

      // Move the collected materialized temporaries into ForRangeInit before
      // ForRangeInitContext exit.
      FRI->LifetimeExtendTemps = std::move(
          Actions.ExprEvalContexts.back().ForRangeLifetimeExtendTemps);
    }

    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, TemplateInfo, 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;
    }

    // C++23 [temp.pre]p5:
    //   In a template-declaration, explicit specialization, or explicit
    //   instantiation the init-declarator-list in the declaration shall
    //   contain at most one declarator.
    if (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
        D.isFirstDeclarator()) {
      Diag(CommaLoc, diag::err_multiple_template_declarators)
          << TemplateInfo.Kind;
    }

    // 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)
      MaybeParseHLSLAnnotations(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, TemplateInfo);
      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;
    bool Entered;

    InitializerScopeRAII(Parser &P, Declarator &D, Decl *ThisDecl)
        : P(P), D(D), ThisDecl(ThisDecl), Entered(false) {
      if (ThisDecl && P.getLangOpts().CPlusPlus) {
        Scope *S = nullptr;
        if (D.getCXXScopeSpec().isSet()) {
          P.EnterScope(0);
          S = P.getCurScope();
        }
        if (ThisDecl && !ThisDecl->isInvalidDecl()) {
          P.Actions.ActOnCXXEnterDeclInitializer(S, ThisDecl);
          Entered = true;
        }
      }
    }
    ~InitializerScopeRAII() {
      if (ThisDecl && P.getLangOpts().CPlusPlus) {
        Scope *S = nullptr;
        if (D.getCXXScopeSpec().isSet())
          S = P.getCurScope();

        if (Entered)
          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;
    }
  }

  SemaCUDA::CUDATargetContextRAII X(Actions.CUDA(),
                                    SemaCUDA::CTCK_InitGlobalVar, ThisDecl);
  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);
      SkipDeletedFunctionBody();
    } 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.CodeCompletion().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;
      }

      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.CodeCompletion().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;
    }

    bool SawError = ParseExpressionList(Exprs, ExpressionStarts);

    if (SawError) {
      if (ThisVarDecl && PP.isCodeCompletionReached() && !CalledSignatureHelp) {
        Actions.CodeCompletion().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();

      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());

    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) {
  ParsedTemplateInfo TemplateInfo;
  /// 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, TemplateInfo, 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,
                              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.LookupName(R, getCurScope())) {
        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::CXXNew:
    return DeclSpecContext::DSC_new;
  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::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);
  }
}

void Parser::DistributeCLateParsedAttrs(Decl *Dcl,
                                        LateParsedAttrList *LateAttrs) {
  if (!LateAttrs)
    return;

  if (Dcl) {
    for (auto *LateAttr : *LateAttrs) {
      if (LateAttr->Decls.empty())
        LateAttr->addDecl(Dcl);
    }
  }
}

/// Bounds attributes (e.g., counted_by):
///   AttrName '(' expression ')'
void Parser::ParseBoundsAttribute(IdentifierInfo &AttrName,
                                  SourceLocation AttrNameLoc,
                                  ParsedAttributes &Attrs,
                                  IdentifierInfo *ScopeName,
                                  SourceLocation ScopeLoc,
                                  ParsedAttr::Form Form) {
  assert(Tok.is(tok::l_paren) && "Attribute arg list not starting with '('");

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

  if (Tok.is(tok::r_paren)) {
    Diag(Tok.getLocation(), diag::err_argument_required_after_attribute);
    Parens.consumeClose();
    return;
  }

  ArgsVector ArgExprs;
  // Don't evaluate argument when the attribute is ignored.
  using ExpressionKind =
      Sema::ExpressionEvaluationContextRecord::ExpressionKind;
  EnterExpressionEvaluationContext EC(
      Actions, Sema::ExpressionEvaluationContext::PotentiallyEvaluated, nullptr,
      ExpressionKind::EK_AttrArgument);

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

  if (ArgExpr.isInvalid()) {
    Parens.skipToEnd();
    return;
  }

  ArgExprs.push_back(ArgExpr.get());
  Parens.consumeClose();

  ASTContext &Ctx = Actions.getASTContext();

  ArgExprs.push_back(IntegerLiteral::Create(
      Ctx, llvm::APInt(Ctx.getTypeSize(Ctx.getSizeType()), 0),
      Ctx.getSizeType(), SourceLocation()));

  Attrs.addNew(&AttrName, SourceRange(AttrNameLoc, Parens.getCloseLocation()),
               ScopeName, ScopeLoc, ArgExprs.data(), ArgExprs.size(), Form);
}

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;
}

/// 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, 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 / C23 attributes that aren't type attributes.
        for (const ParsedAttr &PA : attrs) {
          if (!PA.isCXX11Attribute() && !PA.isC23Attribute() &&
              !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 / C23 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;

    // alignment-specifier
    case tok::kw__Alignas:
      diagnoseUseOfC11Keyword(Tok);
      [[fallthrough]];
    case tok::kw_alignas:
      // _Alignas and alignas (C23, not C++) should parse the same way. The C++
      // parsing for alignas happens through the usual attribute parsing. This
      // ensures that an alignas specifier can appear in a type position in C
      // despite that not being valid in C++.
      if (getLangOpts().C23 || Tok.getKind() == tok::kw__Alignas) {
        if (Tok.getKind() == tok::kw_alignas)
          Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
        ParseAlignmentSpecifier(DS.getAttributes());
        continue;
      }
      [[fallthrough]];
    case tok::l_square:
      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: {
      SemaCodeCompletion::ParserCompletionContext CCC =
          SemaCodeCompletion::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.CodeCompletion().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
                  ? SemaCodeCompletion::PCC_MemberTemplate
                  : SemaCodeCompletion::PCC_Template;
      else if (DSContext == DeclSpecContext::DSC_class)
        CCC = SemaCodeCompletion::PCC_Class;
      else if (getCurScope()->getFnParent() || getCurScope()->getBlockParent())
        CCC = SemaCodeCompletion::PCC_LocalDeclarationSpecifiers;
      else if (CurParsedObjCImpl)
        CCC = SemaCodeCompletion::PCC_ObjCImplementation;

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

    case tok::coloncolon: // ::foo::bar
      // C++ scope specifier.  Annotate and loop, or bail out on error.
      if (getLangOpts().CPlusPlus &&
          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();

      TemplateIdAnnotation *TemplateId = Next.is(tok::annot_template_id)
                                             ? takeTemplateIdAnnotation(Next)
                                             : nullptr;
      if (TemplateId && TemplateId->hasInvalidName()) {
        // We found something like 'T::U<Args> x', but U is not a template.
        // Assume it was supposed to be a type.
        DS.SetTypeSpecError();
        ConsumeAnnotationToken();
        break;
      }

      if (TemplateId && TemplateId->Kind == TNK_Type_template) {
        // We have a qualified template-id, e.g., N::A<int>

        // If this would be a valid constructor declaration with template
        // arguments, we will reject the attempt to form an invalid type-id
        // referring to the injected-class-name when we annotate the token,
        // per C++ [class.qual]p2.
        //
        // To improve diagnostics for this case, parse the declaration as a
        // constructor (and reject the extra template arguments later).
        if ((DSContext == DeclSpecContext::DSC_top_level ||
             DSContext == DeclSpecContext::DSC_class) &&
            TemplateId->Name &&
            Actions.isCurrentClassName(*TemplateId->Name, getCurScope(), &SS) &&
            isConstructorDeclarator(/*Unqualified=*/false,
                                    /*DeductionGuide=*/false,
                                    DS.isFriendSpecified())) {
          // The user meant this to be an out-of-line constructor
          // definition, but template arguments are not allowed
          // there.  Just allow this as a constructor; we'll
          // complain about it later.
          goto DoneWithDeclSpec;
        }

        DS.getTypeSpecScope() = SS;
        ConsumeAnnotationToken(); // The C++ scope.
        assert(Tok.is(tok::annot_template_id) &&
               "ParseOptionalCXXScopeSpecifier not working");
        AnnotateTemplateIdTokenAsType(SS, AllowImplicitTypename);
        continue;
      }

      if (TemplateId && TemplateId->Kind == TNK_Concept_template) {
        DS.getTypeSpecScope() = SS;
        // This is probably a qualified placeholder-specifier, e.g., ::C<int>
        // auto ... Consume the scope annotation and continue to consume the
        // template-id as a placeholder-specifier. Let the next iteration
        // diagnose a missing auto.
        ConsumeAnnotationToken();
        continue;
      }

      if (Next.is(tok::annot_typename)) {
        DS.getTypeSpecScope() = SS;
        ConsumeAnnotationToken(); // The C++ scope.
        TypeResult T = getTypeAnnotation(Tok);
        isInvalid = DS.SetTypeSpecType(DeclSpec::TST_typename,
                                       Tok.getAnnotationEndLoc(),
                                       PrevSpec, DiagID, T, Policy);
        if (isInvalid)
          break;
        DS.SetRangeEnd(Tok.getAnnotationEndLoc());
        ConsumeAnnotationToken(); // The typename
      }

      if (AllowImplicitTypename == ImplicitTypenameContext::Yes &&
          Next.is(tok::annot_template_id) &&
          static_cast<TemplateIdAnnotation *>(Next.getAnnotationValue())
                  ->Kind == TNK_Dependent_template_name) {
        DS.getTypeSpecScope() = SS;
        ConsumeAnnotationToken(); // The C++ scope.
        AnnotateTemplateIdTokenAsType(SS, AllowImplicitTypename);
        continue;
      }

      if (Next.isNot(tok::identifier))
        goto DoneWithDeclSpec;

      // Check whether this is a constructor declaration. If we're in a
      // context where the identifier could be a class name, and it has the
      // shape of a constructor declaration, process it as one.
      if ((DSContext == DeclSpecContext::DSC_top_level ||
           DSContext == DeclSpecContext::DSC_class) &&
          Actions.isCurrentClassName(*Next.getIdentifierInfo(), getCurScope(),
                                     &SS) &&
          isConstructorDeclarator(/*Unqualified=*/false,
                                  /*DeductionGuide=*/false,
                                  DS.isFriendSpecified(),
                                  &TemplateInfo))
        goto DoneWithDeclSpec;

      // C++20 [temp.spec] 13.9/6.
      // This disables the access checking rules for function template explicit
      // instantiation and explicit specialization:
      // - `return type`.
      SuppressAccessChecks SAC(*this, IsTemplateSpecOrInst);

      ParsedType TypeRep = Actions.getTypeName(
          *Next.getIdentifierInfo(), Next.getLocation(), getCurScope(), &SS,
          false, false, nullptr,
          /*IsCtorOrDtorName=*/false,
          /*WantNontrivialTypeSourceInfo=*/true,
          isClassTemplateDeductionContext(DSContext), AllowImplicitTypename);

      if (IsTemplateSpecOrInst)
        SAC.done();

      // If the referenced identifier is not a type, then this declspec is
      // erroneous: We already checked about that it has no type specifier, and
      // C++ doesn't have implicit int.  Diagnose it as a typo w.r.t. to the
      // typename.
      if (!TypeRep) {
        if (TryAnnotateTypeConstraint())
          goto DoneWithDeclSpec;
        if (Tok.isNot(tok::annot_cxxscope) ||
            NextToken().isNot(tok::identifier))
          continue;
        // Eat the scope spec so the identifier is current.
        ConsumeAnnotationToken();
        ParsedAttributes Attrs(AttrFactory);
        if (ParseImplicitInt(DS, &SS, TemplateInfo, AS, DSContext, Attrs)) {
          if (!Attrs.empty()) {
            AttrsLastTime = true;
            attrs.takeAllFrom(Attrs);
          }
          continue;
        }
        goto DoneWithDeclSpec;
      }

      DS.getTypeSpecScope() = SS;
      ConsumeAnnotationToken(); // The C++ scope.

      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec,
                                     DiagID, TypeRep, Policy);
      if (isInvalid)
        break;

      DS.SetRangeEnd(Tok.getLocation());
      ConsumeToken(); // The typename.

      continue;
    }

    case tok::annot_typename: {
      // If we've previously seen a tag definition, we were almost surely
      // missing a semicolon after it.
      if (DS.hasTypeSpecifier() && DS.hasTagDefinition())
        goto DoneWithDeclSpec;

      TypeResult T = getTypeAnnotation(Tok);
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec,
                                     DiagID, T, Policy);
      if (isInvalid)
        break;

      DS.SetRangeEnd(Tok.getAnnotationEndLoc());
      ConsumeAnnotationToken(); // The typename

      continue;
    }

    case tok::kw___is_signed:
      // GNU libstdc++ 4.4 uses __is_signed as an identifier, but Clang
      // typically treats it as a trait. If we see __is_signed as it appears
      // in libstdc++, e.g.,
      //
      //   static const bool __is_signed;
      //
      // then treat __is_signed as an identifier rather than as a keyword.
      if (DS.getTypeSpecType() == TST_bool &&
          DS.getTypeQualifiers() == DeclSpec::TQ_const &&
          DS.getStorageClassSpec() == DeclSpec::SCS_static)
        TryKeywordIdentFallback(true);

      // We're done with the declaration-specifiers.
      goto DoneWithDeclSpec;

      // typedef-name
    case tok::kw___super:
    case tok::kw_decltype:
    case tok::identifier:
    ParseIdentifier: {
      // This identifier can only be a typedef name if we haven't already seen
      // a type-specifier.  Without this check we misparse:
      //  typedef int X; struct Y { short X; };  as 'short int'.
      if (DS.hasTypeSpecifier())
        goto DoneWithDeclSpec;

      // If the token is an identifier named "__declspec" and Microsoft
      // extensions are not enabled, it is likely that there will be cascading
      // parse errors if this really is a __declspec attribute. Attempt to
      // recognize that scenario and recover gracefully.
      if (!getLangOpts().DeclSpecKeyword && Tok.is(tok::identifier) &&
          Tok.getIdentifierInfo()->getName() == "__declspec") {
        Diag(Loc, diag::err_ms_attributes_not_enabled);

        // The next token should be an open paren. If it is, eat the entire
        // attribute declaration and continue.
        if (NextToken().is(tok::l_paren)) {
          // Consume the __declspec identifier.
          ConsumeToken();

          // Eat the parens and everything between them.
          BalancedDelimiterTracker T(*this, tok::l_paren);
          if (T.consumeOpen()) {
            assert(false && "Not a left paren?");
            return;
          }
          T.skipToEnd();
          continue;
        }
      }

      // In C++, check to see if this is a scope specifier like foo::bar::, if
      // so handle it as such.  This is important for ctor parsing.
      if (getLangOpts().CPlusPlus) {
        // C++20 [temp.spec] 13.9/6.
        // This disables the access checking rules for function template
        // explicit instantiation and explicit specialization:
        // - `return type`.
        SuppressAccessChecks SAC(*this, IsTemplateSpecOrInst);

        const bool Success = TryAnnotateCXXScopeToken(EnteringContext);

        if (IsTemplateSpecOrInst)
          SAC.done();

        if (Success) {
          if (IsTemplateSpecOrInst)
            SAC.redelay();
          DS.SetTypeSpecError();
          goto DoneWithDeclSpec;
        }

        if (!Tok.is(tok::identifier))
          continue;
      }

      // Check for need to substitute AltiVec keyword tokens.
      if (TryAltiVecToken(DS, Loc, PrevSpec, DiagID, isInvalid))
        break;

      // [AltiVec] 2.2: [If the 'vector' specifier is used] The syntax does not
      //                allow the use of a typedef name as a type specifier.
      if (DS.isTypeAltiVecVector())
        goto DoneWithDeclSpec;

      if (DSContext == DeclSpecContext::DSC_objc_method_result &&
          isObjCInstancetype()) {
        ParsedType TypeRep = Actions.ObjC().ActOnObjCInstanceType(Loc);
        assert(TypeRep);
        isInvalid = DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec,
                                       DiagID, TypeRep, Policy);
        if (isInvalid)
          break;

        DS.SetRangeEnd(Loc);
        ConsumeToken();
        continue;
      }

      // If we're in a context where the identifier could be a class name,
      // check whether this is a constructor declaration.
      if (getLangOpts().CPlusPlus && DSContext == DeclSpecContext::DSC_class &&
          Actions.isCurrentClassName(*Tok.getIdentifierInfo(), getCurScope()) &&
          isConstructorDeclarator(/*Unqualified=*/true,
                                  /*DeductionGuide=*/false,
                                  DS.isFriendSpecified()))
        goto DoneWithDeclSpec;

      ParsedType TypeRep = Actions.getTypeName(
          *Tok.getIdentifierInfo(), Tok.getLocation(), getCurScope(), nullptr,
          false, false, nullptr, false, false,
          isClassTemplateDeductionContext(DSContext));

      // If this is not a typedef name, don't parse it as part of the declspec,
      // it must be an implicit int or an error.
      if (!TypeRep) {
        if (TryAnnotateTypeConstraint())
          goto DoneWithDeclSpec;
        if (Tok.isNot(tok::identifier))
          continue;
        ParsedAttributes Attrs(AttrFactory);
        if (ParseImplicitInt(DS, nullptr, TemplateInfo, AS, DSContext, Attrs)) {
          if (!Attrs.empty()) {
            AttrsLastTime = true;
            attrs.takeAllFrom(Attrs);
          }
          continue;
        }
        goto DoneWithDeclSpec;
      }

      // Likewise, if this is a context where the identifier could be a template
      // name, check whether this is a deduction guide declaration.
      CXXScopeSpec SS;
      if (getLangOpts().CPlusPlus17 &&
          (DSContext == DeclSpecContext::DSC_class ||
           DSContext == DeclSpecContext::DSC_top_level) &&
          Actions.isDeductionGuideName(getCurScope(), *Tok.getIdentifierInfo(),
                                       Tok.getLocation(), SS) &&
          isConstructorDeclarator(/*Unqualified*/ true,
                                  /*DeductionGuide*/ true))
        goto DoneWithDeclSpec;

      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_typename, Loc, PrevSpec,
                                     DiagID, TypeRep, Policy);
      if (isInvalid)
        break;

      DS.SetRangeEnd(Tok.getLocation());
      ConsumeToken(); // The identifier

      // Objective-C supports type arguments and protocol references
      // following an Objective-C object or object pointer
      // type. Handle either one of them.
      if (Tok.is(tok::less) && getLangOpts().ObjC) {
        SourceLocation NewEndLoc;
        TypeResult NewTypeRep = parseObjCTypeArgsAndProtocolQualifiers(
                                  Loc, TypeRep, /*consumeLastToken=*/true,
                                  NewEndLoc);
        if (NewTypeRep.isUsable()) {
          DS.UpdateTypeRep(NewTypeRep.get());
          DS.SetRangeEnd(NewEndLoc);
        }
      }

      // Need to support trailing type qualifiers (e.g. "id<p> const").
      // If a type specifier follows, it will be diagnosed elsewhere.
      continue;
    }

      // type-name or placeholder-specifier
    case tok::annot_template_id: {
      TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);

      if (TemplateId->hasInvalidName()) {
        DS.SetTypeSpecError();
        break;
      }

      if (TemplateId->Kind == TNK_Concept_template) {
        // If we've already diagnosed that this type-constraint has invalid
        // arguments, drop it and just form 'auto' or 'decltype(auto)'.
        if (TemplateId->hasInvalidArgs())
          TemplateId = nullptr;

        // Any of the following tokens are likely the start of the user
        // forgetting 'auto' or 'decltype(auto)', so diagnose.
        // Note: if updating this list, please make sure we update
        // isCXXDeclarationSpecifier's check for IsPlaceholderSpecifier to have
        // a matching list.
        if (NextToken().isOneOf(tok::identifier, tok::kw_const,
                                tok::kw_volatile, tok::kw_restrict, tok::amp,
                                tok::ampamp)) {
          Diag(Loc, diag::err_placeholder_expected_auto_or_decltype_auto)
              << FixItHint::CreateInsertion(NextToken().getLocation(), "auto");
          // Attempt to continue as if 'auto' was placed here.
          isInvalid = DS.SetTypeSpecType(TST_auto, Loc, PrevSpec, DiagID,
                                         TemplateId, Policy);
          break;
        }
        if (!NextToken().isOneOf(tok::kw_auto, tok::kw_decltype))
            goto DoneWithDeclSpec;

        if (TemplateId && !isInvalid && Actions.CheckTypeConstraint(TemplateId))
            TemplateId = nullptr;

        ConsumeAnnotationToken();
        SourceLocation AutoLoc = Tok.getLocation();
        if (TryConsumeToken(tok::kw_decltype)) {
          BalancedDelimiterTracker Tracker(*this, tok::l_paren);
          if (Tracker.consumeOpen()) {
            // Something like `void foo(Iterator decltype i)`
            Diag(Tok, diag::err_expected) << tok::l_paren;
          } else {
            if (!TryConsumeToken(tok::kw_auto)) {
              // Something like `void foo(Iterator decltype(int) i)`
              Tracker.skipToEnd();
              Diag(Tok, diag::err_placeholder_expected_auto_or_decltype_auto)
                << FixItHint::CreateReplacement(SourceRange(AutoLoc,
                                                            Tok.getLocation()),
                                                "auto");
            } else {
              Tracker.consumeClose();
            }
          }
          ConsumedEnd = Tok.getLocation();
          DS.setTypeArgumentRange(Tracker.getRange());
          // Even if something went wrong above, continue as if we've seen
          // `decltype(auto)`.
          isInvalid = DS.SetTypeSpecType(TST_decltype_auto, Loc, PrevSpec,
                                         DiagID, TemplateId, Policy);
        } else {
          isInvalid = DS.SetTypeSpecType(TST_auto, AutoLoc, PrevSpec, DiagID,
                                         TemplateId, Policy);
        }
        break;
      }

      if (TemplateId->Kind != TNK_Type_template &&
          TemplateId->Kind != TNK_Undeclared_template) {
        // This template-id does not refer to a type name, so we're
        // done with the type-specifiers.
        goto DoneWithDeclSpec;
      }

      // If we're in a context where the template-id could be a
      // constructor name or specialization, check whether this is a
      // constructor declaration.
      if (getLangOpts().CPlusPlus && DSContext == DeclSpecContext::DSC_class &&
          Actions.isCurrentClassName(*TemplateId->Name, getCurScope()) &&
          isConstructorDeclarator(/*Unqualified=*/true,
                                  /*DeductionGuide=*/false,
                                  DS.isFriendSpecified()))
        goto DoneWithDeclSpec;

      // Turn the template-id annotation token into a type annotation
      // token, then try again to parse it as a type-specifier.
      CXXScopeSpec SS;
      AnnotateTemplateIdTokenAsType(SS, AllowImplicitTypename);
      continue;
    }

    // Attributes support.
    case tok::kw___attribute:
    case tok::kw___declspec:
      ParseAttributes(PAKM_GNU | PAKM_Declspec, DS.getAttributes(), LateAttrs);
      continue;

    // Microsoft single token adornments.
    case tok::kw___forceinline: {
      isInvalid = DS.setFunctionSpecForceInline(Loc, PrevSpec, DiagID);
      IdentifierInfo *AttrName = Tok.getIdentifierInfo();
      SourceLocation AttrNameLoc = Tok.getLocation();
      DS.getAttributes().addNew(AttrName, AttrNameLoc, nullptr, AttrNameLoc,
                                nullptr, 0, tok::kw___forceinline);
      break;
    }

    case tok::kw___unaligned:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_unaligned, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;

    case tok::kw___sptr:
    case tok::kw___uptr:
    case tok::kw___ptr64:
    case tok::kw___ptr32:
    case tok::kw___w64:
    case tok::kw___cdecl:
    case tok::kw___stdcall:
    case tok::kw___fastcall:
    case tok::kw___thiscall:
    case tok::kw___regcall:
    case tok::kw___vectorcall:
      ParseMicrosoftTypeAttributes(DS.getAttributes());
      continue;

    case tok::kw___funcref:
      ParseWebAssemblyFuncrefTypeAttribute(DS.getAttributes());
      continue;

    // Borland single token adornments.
    case tok::kw___pascal:
      ParseBorlandTypeAttributes(DS.getAttributes());
      continue;

    // OpenCL single token adornments.
    case tok::kw___kernel:
      ParseOpenCLKernelAttributes(DS.getAttributes());
      continue;

    // CUDA/HIP single token adornments.
    case tok::kw___noinline__:
      ParseCUDAFunctionAttributes(DS.getAttributes());
      continue;

    // Nullability type specifiers.
    case tok::kw__Nonnull:
    case tok::kw__Nullable:
    case tok::kw__Nullable_result:
    case tok::kw__Null_unspecified:
      ParseNullabilityTypeSpecifiers(DS.getAttributes());
      continue;

    // Objective-C 'kindof' types.
    case tok::kw___kindof:
      DS.getAttributes().addNew(Tok.getIdentifierInfo(), Loc, nullptr, Loc,
                                nullptr, 0, tok::kw___kindof);
      (void)ConsumeToken();
      continue;

    // storage-class-specifier
    case tok::kw_typedef:
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_typedef, Loc,
                                         PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw_extern:
      if (DS.getThreadStorageClassSpec() == DeclSpec::TSCS___thread)
        Diag(Tok, diag::ext_thread_before) << "extern";
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_extern, Loc,
                                         PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw___private_extern__:
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_private_extern,
                                         Loc, PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw_static:
      if (DS.getThreadStorageClassSpec() == DeclSpec::TSCS___thread)
        Diag(Tok, diag::ext_thread_before) << "static";
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_static, Loc,
                                         PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw_auto:
      if (getLangOpts().CPlusPlus11 || getLangOpts().C23) {
        if (isKnownToBeTypeSpecifier(GetLookAheadToken(1))) {
          isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_auto, Loc,
                                             PrevSpec, DiagID, Policy);
          if (!isInvalid && !getLangOpts().C23)
            Diag(Tok, diag::ext_auto_storage_class)
              << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
        } else
          isInvalid = DS.SetTypeSpecType(DeclSpec::TST_auto, Loc, PrevSpec,
                                         DiagID, Policy);
      } else
        isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_auto, Loc,
                                           PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw___auto_type:
      Diag(Tok, diag::ext_auto_type);
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_auto_type, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_register:
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_register, Loc,
                                         PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw_mutable:
      isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_mutable, Loc,
                                         PrevSpec, DiagID, Policy);
      isStorageClass = true;
      break;
    case tok::kw___thread:
      isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS___thread, Loc,
                                               PrevSpec, DiagID);
      isStorageClass = true;
      break;
    case tok::kw_thread_local:
      if (getLangOpts().C23)
        Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
      // We map thread_local to _Thread_local in C23 mode so it retains the C
      // semantics rather than getting the C++ semantics.
      // FIXME: diagnostics will show _Thread_local when the user wrote
      // thread_local in source in C23 mode; we need some general way to
      // identify which way the user spelled the keyword in source.
      isInvalid = DS.SetStorageClassSpecThread(
          getLangOpts().C23 ? DeclSpec::TSCS__Thread_local
                            : DeclSpec::TSCS_thread_local,
          Loc, PrevSpec, DiagID);
      isStorageClass = true;
      break;
    case tok::kw__Thread_local:
      diagnoseUseOfC11Keyword(Tok);
      isInvalid = DS.SetStorageClassSpecThread(DeclSpec::TSCS__Thread_local,
                                               Loc, PrevSpec, DiagID);
      isStorageClass = true;
      break;

    // function-specifier
    case tok::kw_inline:
      isInvalid = DS.setFunctionSpecInline(Loc, PrevSpec, DiagID);
      break;
    case tok::kw_virtual:
      // C++ for OpenCL does not allow virtual function qualifier, to avoid
      // function pointers restricted in OpenCL v2.0 s6.9.a.
      if (getLangOpts().OpenCLCPlusPlus &&
          !getActions().getOpenCLOptions().isAvailableOption(
              "__cl_clang_function_pointers", getLangOpts())) {
        DiagID = diag::err_openclcxx_virtual_function;
        PrevSpec = Tok.getIdentifierInfo()->getNameStart();
        isInvalid = true;
      } else {
        isInvalid = DS.setFunctionSpecVirtual(Loc, PrevSpec, DiagID);
      }
      break;
    case tok::kw_explicit: {
      SourceLocation ExplicitLoc = Loc;
      SourceLocation CloseParenLoc;
      ExplicitSpecifier ExplicitSpec(nullptr, ExplicitSpecKind::ResolvedTrue);
      ConsumedEnd = ExplicitLoc;
      ConsumeToken(); // kw_explicit
      if (Tok.is(tok::l_paren)) {
        if (getLangOpts().CPlusPlus20 || isExplicitBool() == TPResult::True) {
          Diag(Tok.getLocation(), getLangOpts().CPlusPlus20
                                      ? diag::warn_cxx17_compat_explicit_bool
                                      : diag::ext_explicit_bool);

          ExprResult ExplicitExpr(static_cast<Expr *>(nullptr));
          BalancedDelimiterTracker Tracker(*this, tok::l_paren);
          Tracker.consumeOpen();

          EnterExpressionEvaluationContext ConstantEvaluated(
              Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);

          ExplicitExpr = ParseConstantExpressionInExprEvalContext();
          ConsumedEnd = Tok.getLocation();
          if (ExplicitExpr.isUsable()) {
            CloseParenLoc = Tok.getLocation();
            Tracker.consumeClose();
            ExplicitSpec =
                Actions.ActOnExplicitBoolSpecifier(ExplicitExpr.get());
          } else
            Tracker.skipToEnd();
        } else {
          Diag(Tok.getLocation(), diag::warn_cxx20_compat_explicit_bool);
        }
      }
      isInvalid = DS.setFunctionSpecExplicit(ExplicitLoc, PrevSpec, DiagID,
                                             ExplicitSpec, CloseParenLoc);
      break;
    }
    case tok::kw__Noreturn:
      diagnoseUseOfC11Keyword(Tok);
      isInvalid = DS.setFunctionSpecNoreturn(Loc, PrevSpec, DiagID);
      break;

    // friend
    case tok::kw_friend:
      if (DSContext == DeclSpecContext::DSC_class) {
        isInvalid = DS.SetFriendSpec(Loc, PrevSpec, DiagID);
        Scope *CurS = getCurScope();
        if (!isInvalid && CurS)
          CurS->setFlags(CurS->getFlags() | Scope::FriendScope);
      } else {
        PrevSpec = ""; // not actually used by the diagnostic
        DiagID = diag::err_friend_invalid_in_context;
        isInvalid = true;
      }
      break;

    // Modules
    case tok::kw___module_private__:
      isInvalid = DS.setModulePrivateSpec(Loc, PrevSpec, DiagID);
      break;

    // constexpr, consteval, constinit specifiers
    case tok::kw_constexpr:
      if (getLangOpts().C23)
        Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
      isInvalid = DS.SetConstexprSpec(ConstexprSpecKind::Constexpr, Loc,
                                      PrevSpec, DiagID);
      break;
    case tok::kw_consteval:
      isInvalid = DS.SetConstexprSpec(ConstexprSpecKind::Consteval, Loc,
                                      PrevSpec, DiagID);
      break;
    case tok::kw_constinit:
      isInvalid = DS.SetConstexprSpec(ConstexprSpecKind::Constinit, Loc,
                                      PrevSpec, DiagID);
      break;

    // type-specifier
    case tok::kw_short:
      isInvalid = DS.SetTypeSpecWidth(TypeSpecifierWidth::Short, Loc, PrevSpec,
                                      DiagID, Policy);
      break;
    case tok::kw_long:
      if (DS.getTypeSpecWidth() != TypeSpecifierWidth::Long)
        isInvalid = DS.SetTypeSpecWidth(TypeSpecifierWidth::Long, Loc, PrevSpec,
                                        DiagID, Policy);
      else
        isInvalid = DS.SetTypeSpecWidth(TypeSpecifierWidth::LongLong, Loc,
                                        PrevSpec, DiagID, Policy);
      break;
    case tok::kw___int64:
      isInvalid = DS.SetTypeSpecWidth(TypeSpecifierWidth::LongLong, Loc,
                                      PrevSpec, DiagID, Policy);
      break;
    case tok::kw_signed:
      isInvalid =
          DS.SetTypeSpecSign(TypeSpecifierSign::Signed, Loc, PrevSpec, DiagID);
      break;
    case tok::kw_unsigned:
      isInvalid = DS.SetTypeSpecSign(TypeSpecifierSign::Unsigned, Loc, PrevSpec,
                                     DiagID);
      break;
    case tok::kw__Complex:
      if (!getLangOpts().C99)
        Diag(Tok, diag::ext_c99_feature) << Tok.getName();
      isInvalid = DS.SetTypeSpecComplex(DeclSpec::TSC_complex, Loc, PrevSpec,
                                        DiagID);
      break;
    case tok::kw__Imaginary:
      if (!getLangOpts().C99)
        Diag(Tok, diag::ext_c99_feature) << Tok.getName();
      isInvalid = DS.SetTypeSpecComplex(DeclSpec::TSC_imaginary, Loc, PrevSpec,
                                        DiagID);
      break;
    case tok::kw_void:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_void, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_char:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_char, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_int:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_int, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw__ExtInt:
    case tok::kw__BitInt: {
      DiagnoseBitIntUse(Tok);
      ExprResult ER = ParseExtIntegerArgument();
      if (ER.isInvalid())
        continue;
      isInvalid = DS.SetBitIntType(Loc, ER.get(), PrevSpec, DiagID, Policy);
      ConsumedEnd = PrevTokLocation;
      break;
    }
    case tok::kw___int128:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_int128, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_half:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_half, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw___bf16:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_BFloat16, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_float:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_double:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_double, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw__Float16:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float16, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw__Accum:
      assert(getLangOpts().FixedPoint &&
             "This keyword is only used when fixed point types are enabled "
             "with `-ffixed-point`");
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_accum, Loc, PrevSpec, DiagID,
                                     Policy);
      break;
    case tok::kw__Fract:
      assert(getLangOpts().FixedPoint &&
             "This keyword is only used when fixed point types are enabled "
             "with `-ffixed-point`");
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_fract, Loc, PrevSpec, DiagID,
                                     Policy);
      break;
    case tok::kw__Sat:
      assert(getLangOpts().FixedPoint &&
             "This keyword is only used when fixed point types are enabled "
             "with `-ffixed-point`");
      isInvalid = DS.SetTypeSpecSat(Loc, PrevSpec, DiagID);
      break;
    case tok::kw___float128:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_float128, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw___ibm128:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_ibm128, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_wchar_t:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_wchar, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_char8_t:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_char8, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_char16_t:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_char16, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_char32_t:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_char32, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw_bool:
      if (getLangOpts().C23)
        Diag(Tok, diag::warn_c23_compat_keyword) << Tok.getName();
      [[fallthrough]];
    case tok::kw__Bool:
      if (Tok.is(tok::kw__Bool) && !getLangOpts().C99)
        Diag(Tok, diag::ext_c99_feature) << Tok.getName();

      if (Tok.is(tok::kw_bool) &&
          DS.getTypeSpecType() != DeclSpec::TST_unspecified &&
          DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
        PrevSpec = ""; // Not used by the diagnostic.
        DiagID = diag::err_bool_redeclaration;
        // For better error recovery.
        Tok.setKind(tok::identifier);
        isInvalid = true;
      } else {
        isInvalid = DS.SetTypeSpecType(DeclSpec::TST_bool, Loc, PrevSpec,
                                       DiagID, Policy);
      }
      break;
    case tok::kw__Decimal32:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_decimal32, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw__Decimal64:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_decimal64, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw__Decimal128:
      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_decimal128, Loc, PrevSpec,
                                     DiagID, Policy);
      break;
    case tok::kw___vector:
      isInvalid = DS.SetTypeAltiVecVector(true, Loc, PrevSpec, DiagID, Policy);
      break;
    case tok::kw___pixel:
      isInvalid = DS.SetTypeAltiVecPixel(true, Loc, PrevSpec, DiagID, Policy);
      break;
    case tok::kw___bool:
      isInvalid = DS.SetTypeAltiVecBool(true, Loc, PrevSpec, DiagID, Policy);
      break;
    case tok::kw_pipe:
      if (!getLangOpts().OpenCL ||
          getLangOpts().getOpenCLCompatibleVersion() < 200) {
        // OpenCL 2.0 and later define this keyword. OpenCL 1.2 and earlier
        // should support the "pipe" word as identifier.
        Tok.getIdentifierInfo()->revertTokenIDToIdentifier();
        Tok.setKind(tok::identifier);
        goto DoneWithDeclSpec;
      } else if (!getLangOpts().OpenCLPipes) {
        DiagID = diag::err_opencl_unknown_type_specifier;
        PrevSpec = Tok.getIdentifierInfo()->getNameStart();
        isInvalid = true;
      } else
        isInvalid = DS.SetTypePipe(true, Loc, PrevSpec, DiagID, Policy);
      break;
// We only need to enumerate each image type once.
#define IMAGE_READ_WRITE_TYPE(Type, Id, Ext)
#define IMAGE_WRITE_TYPE(Type, Id, Ext)
#define IMAGE_READ_TYPE(ImgType, Id, Ext) \
    case tok::kw_##ImgType##_t: \
      if (!handleOpenCLImageKW(Ext, DeclSpec::TST_##ImgType##_t)) \
        goto DoneWithDeclSpec; \
      break;
#include "clang/Basic/OpenCLImageTypes.def"
    case tok::kw___unknown_anytype:
      isInvalid = DS.SetTypeSpecType(TST_unknown_anytype, Loc,
                                     PrevSpec, DiagID, Policy);
      break;

    // class-specifier:
    case tok::kw_class:
    case tok::kw_struct:
    case tok::kw___interface:
    case tok::kw_union: {
      tok::TokenKind Kind = Tok.getKind();
      ConsumeToken();

      // These are attributes following class specifiers.
      // To produce better diagnostic, we parse them when
      // parsing class specifier.
      ParsedAttributes Attributes(AttrFactory);
      ParseClassSpecifier(Kind, Loc, DS, TemplateInfo, AS,
                          EnteringContext, DSContext, Attributes);

      // If there are attributes following class specifier,
      // take them over and handle them here.
      if (!Attributes.empty()) {
        AttrsLastTime = true;
        attrs.takeAllFrom(Attributes);
      }
      continue;
    }

    // enum-specifier:
    case tok::kw_enum:
      ConsumeToken();
      ParseEnumSpecifier(Loc, DS, TemplateInfo, AS, DSContext);
      continue;

    // cv-qualifier:
    case tok::kw_const:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_const, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw_volatile:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_volatile, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw_restrict:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_restrict, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;

    // C++ typename-specifier:
    case tok::kw_typename:
      if (TryAnnotateTypeOrScopeToken()) {
        DS.SetTypeSpecError();
        goto DoneWithDeclSpec;
      }
      if (!Tok.is(tok::kw_typename))
        continue;
      break;

    // C23/GNU typeof support.
    case tok::kw_typeof:
    case tok::kw_typeof_unqual:
      ParseTypeofSpecifier(DS);
      continue;

    case tok::annot_decltype:
      ParseDecltypeSpecifier(DS);
      continue;

    case tok::annot_pack_indexing_type:
      ParsePackIndexingType(DS);
      continue;

    case tok::annot_pragma_pack:
      HandlePragmaPack();
      continue;

    case tok::annot_pragma_ms_pragma:
      HandlePragmaMSPragma();
      continue;

    case tok::annot_pragma_ms_vtordisp:
      HandlePragmaMSVtorDisp();
      continue;

    case tok::annot_pragma_ms_pointers_to_members:
      HandlePragmaMSPointersToMembers();
      continue;

#define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case tok::kw___##Trait:
#include "clang/Basic/TransformTypeTraits.def"
      // HACK: libstdc++ already uses '__remove_cv' as an alias template so we
      // work around this by expecting all transform type traits to be suffixed
      // with '('. They're an identifier otherwise.
      if (!MaybeParseTypeTransformTypeSpecifier(DS))
        goto ParseIdentifier;
      continue;

    case tok::kw__Atomic:
      // C11 6.7.2.4/4:
      //   If the _Atomic keyword is immediately followed by a left parenthesis,
      //   it is interpreted as a type specifier (with a type name), not as a
      //   type qualifier.
      diagnoseUseOfC11Keyword(Tok);
      if (NextToken().is(tok::l_paren)) {
        ParseAtomicSpecifier(DS);
        continue;
      }
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_atomic, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;

    // OpenCL address space qualifiers:
    case tok::kw___generic:
      // generic address space is introduced only in OpenCL v2.0
      // see OpenCL C Spec v2.0 s6.5.5
      // OpenCL v3.0 introduces __opencl_c_generic_address_space
      // feature macro to indicate if generic address space is supported
      if (!Actions.getLangOpts().OpenCLGenericAddressSpace) {
        DiagID = diag::err_opencl_unknown_type_specifier;
        PrevSpec = Tok.getIdentifierInfo()->getNameStart();
        isInvalid = true;
        break;
      }
      [[fallthrough]];
    case tok::kw_private:
      // It's fine (but redundant) to check this for __generic on the
      // fallthrough path; we only form the __generic token in OpenCL mode.
      if (!getLangOpts().OpenCL)
        goto DoneWithDeclSpec;
      [[fallthrough]];
    case tok::kw___private:
    case tok::kw___global:
    case tok::kw___local:
    case tok::kw___constant:
    // OpenCL access qualifiers:
    case tok::kw___read_only:
    case tok::kw___write_only:
    case tok::kw___read_write:
      ParseOpenCLQualifiers(DS.getAttributes());
      break;

    case tok::kw_groupshared:
    case tok::kw_in:
    case tok::kw_inout:
    case tok::kw_out:
      // NOTE: ParseHLSLQualifiers will consume the qualifier token.
      ParseHLSLQualifiers(DS.getAttributes());
      continue;

    case tok::less:
      // GCC ObjC supports types like "<SomeProtocol>" as a synonym for
      // "id<SomeProtocol>".  This is hopelessly old fashioned and dangerous,
      // but we support it.
      if (DS.hasTypeSpecifier() || !getLangOpts().ObjC)
        goto DoneWithDeclSpec;

      SourceLocation StartLoc = Tok.getLocation();
      SourceLocation EndLoc;
      TypeResult Type = parseObjCProtocolQualifierType(EndLoc);
      if (Type.isUsable()) {
        if (DS.SetTypeSpecType(DeclSpec::TST_typename, StartLoc, StartLoc,
                               PrevSpec, DiagID, Type.get(),
                               Actions.getASTContext().getPrintingPolicy()))
          Diag(StartLoc, DiagID) << PrevSpec;

        DS.SetRangeEnd(EndLoc);
      } else {
        DS.SetTypeSpecError();
      }

      // Need to support trailing type qualifiers (e.g. "id<p> const").
      // If a type specifier follows, it will be diagnosed elsewhere.
      continue;
    }

    DS.SetRangeEnd(ConsumedEnd.isValid() ? ConsumedEnd : Tok.getLocation());

    // If the specifier wasn't legal, issue a diagnostic.
    if (isInvalid) {
      assert(PrevSpec && "Method did not return previous specifier!");
      assert(DiagID);

      if (DiagID == diag::ext_duplicate_declspec ||
          DiagID == diag::ext_warn_duplicate_declspec ||
          DiagID == diag::err_duplicate_declspec)
        Diag(Loc, DiagID) << PrevSpec
                          << FixItHint::CreateRemoval(
                                 SourceRange(Loc, DS.getEndLoc()));
      else if (DiagID == diag::err_opencl_unknown_type_specifier) {
        Diag(Loc, DiagID) << getLangOpts().getOpenCLVersionString() << PrevSpec
                          << isStorageClass;
      } else
        Diag(Loc, DiagID) << PrevSpec;
    }

    if (DiagID != diag::err_bool_redeclaration && ConsumedEnd.isInvalid())
      // After an error the next token can be an annotation token.
      ConsumeAnyToken();

    AttrsLastTime = false;
  }
}

static void DiagnoseCountAttributedTypeInUnnamedAnon(ParsingDeclSpec &DS,
                                                     Parser &P) {

  if (DS.getTypeSpecType() != DeclSpec::TST_struct)
    return;

  auto *RD = dyn_cast<RecordDecl>(DS.getRepAsDecl());
  // We're only interested in unnamed, non-anonymous struct
  if (!RD || !RD->getName().empty() || RD->isAnonymousStructOrUnion())
    return;

  for (auto *I : RD->decls()) {
    auto *VD = dyn_cast<ValueDecl>(I);
    if (!VD)
      continue;

    auto *CAT = VD->getType()->getAs<CountAttributedType>();
    if (!CAT)
      continue;

    for (const auto &DD : CAT->dependent_decls()) {
      if (!RD->containsDecl(DD.getDecl())) {
        P.Diag(VD->getBeginLoc(), diag::err_count_attr_param_not_in_same_struct)
            << DD.getDecl() << CAT->getKind() << CAT->isArrayType();
        P.Diag(DD.getDecl()->getBeginLoc(),
               diag::note_flexible_array_counted_by_attr_field)
            << DD.getDecl();
      }
    }
  }
}

/// ParseStructDeclaration - Parse a struct declaration without the terminating
/// semicolon.
///
/// Note that a struct declaration refers to a declaration in a struct,
/// not to the declaration of a struct.
///
///       struct-declaration:
/// [C23]   attributes-specifier-seq[opt]
///           specifier-qualifier-list struct-declarator-list
/// [GNU]   __extension__ struct-declaration
/// [GNU]   specifier-qualifier-list
///       struct-declarator-list:
///         struct-declarator
///         struct-declarator-list ',' struct-declarator
/// [GNU]   struct-declarator-list ',' attributes[opt] struct-declarator
///       struct-declarator:
///         declarator
/// [GNU]   declarator attributes[opt]
///         declarator[opt] ':' constant-expression
/// [GNU]   declarator[opt] ':' constant-expression attributes[opt]
///
void Parser::ParseStructDeclaration(
    ParsingDeclSpec &DS,
    llvm::function_ref<Decl *(ParsingFieldDeclarator &)> FieldsCallback,
    LateParsedAttrList *LateFieldAttrs) {

  if (Tok.is(tok::kw___extension__)) {
    // __extension__ silences extension warnings in the subexpression.
    ExtensionRAIIObject O(Diags);  // Use RAII to do this.
    ConsumeToken();
    return ParseStructDeclaration(DS, FieldsCallback, LateFieldAttrs);
  }

  // Parse leading attributes.
  ParsedAttributes Attrs(AttrFactory);
  MaybeParseCXX11Attributes(Attrs);

  // Parse the common specifier-qualifiers-list piece.
  ParseSpecifierQualifierList(DS);

  // If there are no declarators, this is a free-standing declaration
  // specifier. Let the actions module cope with it.
  if (Tok.is(tok::semi)) {
    // C23 6.7.2.1p9 : "The optional attribute specifier sequence in a
    // member declaration appertains to each of the members declared by the
    // member declarator list; it shall not appear if the optional member
    // declarator list is omitted."
    ProhibitAttributes(Attrs);
    RecordDecl *AnonRecord = nullptr;
    Decl *TheDecl = Actions.ParsedFreeStandingDeclSpec(
        getCurScope(), AS_none, DS, ParsedAttributesView::none(), AnonRecord);
    assert(!AnonRecord && "Did not expect anonymous struct or union here");
    DS.complete(TheDecl);
    return;
  }

  // Read struct-declarators until we find the semicolon.
  bool FirstDeclarator = true;
  SourceLocation CommaLoc;
  while (true) {
    ParsingFieldDeclarator DeclaratorInfo(*this, DS, Attrs);
    DeclaratorInfo.D.setCommaLoc(CommaLoc);

    // Attributes are only allowed here on successive declarators.
    if (!FirstDeclarator) {
      // However, this does not apply for [[]] attributes (which could show up
      // before or after the __attribute__ attributes).
      DiagnoseAndSkipCXX11Attributes();
      MaybeParseGNUAttributes(DeclaratorInfo.D);
      DiagnoseAndSkipCXX11Attributes();
    }

    /// struct-declarator: declarator
    /// struct-declarator: declarator[opt] ':' constant-expression
    if (Tok.isNot(tok::colon)) {
      // Don't parse FOO:BAR as if it were a typo for FOO::BAR.
      ColonProtectionRAIIObject X(*this);
      ParseDeclarator(DeclaratorInfo.D);
    } else
      DeclaratorInfo.D.SetIdentifier(nullptr, Tok.getLocation());

    // Here, we now know that the unnamed struct is not an anonymous struct.
    // Report an error if a counted_by attribute refers to a field in a
    // different named struct.
    DiagnoseCountAttributedTypeInUnnamedAnon(DS, *this);

    if (TryConsumeToken(tok::colon)) {
      ExprResult Res(ParseConstantExpression());
      if (Res.isInvalid())
        SkipUntil(tok::semi, StopBeforeMatch);
      else
        DeclaratorInfo.BitfieldSize = Res.get();
    }

    // If attributes exist after the declarator, parse them.
    MaybeParseGNUAttributes(DeclaratorInfo.D, LateFieldAttrs);

    // We're done with this declarator;  invoke the callback.
    Decl *Field = FieldsCallback(DeclaratorInfo);
    if (Field)
      DistributeCLateParsedAttrs(Field, LateFieldAttrs);

    // If we don't have a comma, it is either the end of the list (a ';')
    // or an error, bail out.
    if (!TryConsumeToken(tok::comma, CommaLoc))
      return;

    FirstDeclarator = false;
  }
}

// TODO: All callers of this function should be moved to
// `Parser::ParseLexedAttributeList`.
void Parser::ParseLexedCAttributeList(LateParsedAttrList &LAs, bool EnterScope,
                                      ParsedAttributes *OutAttrs) {
  assert(LAs.parseSoon() &&
         "Attribute list should be marked for immediate parsing.");
  for (auto *LA : LAs) {
    ParseLexedCAttribute(*LA, EnterScope, OutAttrs);
    delete LA;
  }
  LAs.clear();
}

/// Finish parsing an attribute for which parsing was delayed.
/// This will be called at the end of parsing a class declaration
/// for each LateParsedAttribute. We consume the saved tokens and
/// create an attribute with the arguments filled in. We add this
/// to the Attribute list for the decl.
void Parser::ParseLexedCAttribute(LateParsedAttribute &LA, bool EnterScope,
                                  ParsedAttributes *OutAttrs) {
  // Create a fake EOF so that attribute parsing won't go off the end of the
  // attribute.
  Token AttrEnd;
  AttrEnd.startToken();
  AttrEnd.setKind(tok::eof);
  AttrEnd.setLocation(Tok.getLocation());
  AttrEnd.setEofData(LA.Toks.data());
  LA.Toks.push_back(AttrEnd);

  // Append the current token at the end of the new token stream so that it
  // doesn't get lost.
  LA.Toks.push_back(Tok);
  PP.EnterTokenStream(LA.Toks, /*DisableMacroExpansion=*/true,
                      /*IsReinject=*/true);
  // Drop the current token and bring the first cached one. It's the same token
  // as when we entered this function.
  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);

  // TODO: Use `EnterScope`
  (void)EnterScope;

  ParsedAttributes Attrs(AttrFactory);

  assert(LA.Decls.size() <= 1 &&
         "late field attribute expects to have at most one declaration.");

  // Dispatch based on the attribute and parse it
  ParseGNUAttributeArgs(&LA.AttrName, LA.AttrNameLoc, Attrs, nullptr, nullptr,
                        SourceLocation(), ParsedAttr::Form::GNU(), nullptr);

  for (auto *D : LA.Decls)
    Actions.ActOnFinishDelayedAttribute(getCurScope(), D, Attrs);

  // Due to a parsing error, we either went over the cached tokens or
  // there are still cached tokens left, so we skip the leftover tokens.
  while (Tok.isNot(tok::eof))
    ConsumeAnyToken();

  // Consume the fake EOF token if it's there
  if (Tok.is(tok::eof) && Tok.getEofData() == AttrEnd.getEofData())
    ConsumeAnyToken();

  if (OutAttrs) {
    OutAttrs->takeAllFrom(Attrs);
  }
}

/// ParseStructUnionBody
///       struct-contents:
///         struct-declaration-list
/// [EXT]   empty
/// [GNU]   "struct-declaration-list" without terminating ';'
///       struct-declaration-list:
///         struct-declaration
///         struct-declaration-list struct-declaration
/// [OBC]   '@' 'defs' '(' class-name ')'
///
void Parser::ParseStructUnionBody(SourceLocation RecordLoc,
                                  DeclSpec::TST TagType, RecordDecl *TagDecl) {
  PrettyDeclStackTraceEntry CrashInfo(Actions.Context, TagDecl, RecordLoc,
                                      "parsing struct/union body");
  assert(!getLangOpts().CPlusPlus && "C++ declarations not supported");

  BalancedDelimiterTracker T(*this, tok::l_brace);
  if (T.consumeOpen())
    return;

  ParseScope StructScope(this, Scope::ClassScope|Scope::DeclScope);
  Actions.ActOnTagStartDefinition(getCurScope(), TagDecl);

  // `LateAttrParseExperimentalExtOnly=true` requests that only attributes
  // marked with `LateAttrParseExperimentalExt` are late parsed.
  LateParsedAttrList LateFieldAttrs(/*PSoon=*/true,
                                    /*LateAttrParseExperimentalExtOnly=*/true);

  // While we still have something to read, read the declarations in the struct.
  while (!tryParseMisplacedModuleImport() && Tok.isNot(tok::r_brace) &&
         Tok.isNot(tok::eof)) {
    // Each iteration of this loop reads one struct-declaration.

    // Check for extraneous top-level semicolon.
    if (Tok.is(tok::semi)) {
      ConsumeExtraSemi(InsideStruct, TagType);
      continue;
    }

    // Parse _Static_assert declaration.
    if (Tok.isOneOf(tok::kw__Static_assert, tok::kw_static_assert)) {
      SourceLocation DeclEnd;
      ParseStaticAssertDeclaration(DeclEnd);
      continue;
    }

    if (Tok.is(tok::annot_pragma_pack)) {
      HandlePragmaPack();
      continue;
    }

    if (Tok.is(tok::annot_pragma_align)) {
      HandlePragmaAlign();
      continue;
    }

    if (Tok.isOneOf(tok::annot_pragma_openmp, tok::annot_attr_openmp)) {
      // Result can be ignored, because it must be always empty.
      AccessSpecifier AS = AS_none;
      ParsedAttributes Attrs(AttrFactory);
      (void)ParseOpenMPDeclarativeDirectiveWithExtDecl(AS, Attrs);
      continue;
    }

    if (Tok.is(tok::annot_pragma_openacc)) {
      ParseOpenACCDirectiveDecl();
      continue;
    }

    if (tok::isPragmaAnnotation(Tok.getKind())) {
      Diag(Tok.getLocation(), diag::err_pragma_misplaced_in_decl)
          << DeclSpec::getSpecifierName(
                 TagType, Actions.getASTContext().getPrintingPolicy());
      ConsumeAnnotationToken();
      continue;
    }

    if (!Tok.is(tok::at)) {
      auto CFieldCallback = [&](ParsingFieldDeclarator &FD) -> Decl * {
        // Install the declarator into the current TagDecl.
        Decl *Field =
            Actions.ActOnField(getCurScope(), TagDecl,
                               FD.D.getDeclSpec().getSourceRange().getBegin(),
                               FD.D, FD.BitfieldSize);
        FD.complete(Field);
        return Field;
      };

      // Parse all the comma separated declarators.
      ParsingDeclSpec DS(*this);
      ParseStructDeclaration(DS, CFieldCallback, &LateFieldAttrs);
    } else { // Handle @defs
      ConsumeToken();
      if (!Tok.isObjCAtKeyword(tok::objc_defs)) {
        Diag(Tok, diag::err_unexpected_at);
        SkipUntil(tok::semi);
        continue;
      }
      ConsumeToken();
      ExpectAndConsume(tok::l_paren);
      if (!Tok.is(tok::identifier)) {
        Diag(Tok, diag::err_expected) << tok::identifier;
        SkipUntil(tok::semi);
        continue;
      }
      SmallVector<Decl *, 16> Fields;
      Actions.ObjC().ActOnDefs(getCurScope(), TagDecl, Tok.getLocation(),
                               Tok.getIdentifierInfo(), Fields);
      ConsumeToken();
      ExpectAndConsume(tok::r_paren);
    }

    if (TryConsumeToken(tok::semi))
      continue;

    if (Tok.is(tok::r_brace)) {
      ExpectAndConsume(tok::semi, diag::ext_expected_semi_decl_list);
      break;
    }

    ExpectAndConsume(tok::semi, diag::err_expected_semi_decl_list);
    // Skip to end of block or statement to avoid ext-warning on extra ';'.
    SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
    // If we stopped at a ';', eat it.
    TryConsumeToken(tok::semi);
  }

  T.consumeClose();

  ParsedAttributes attrs(AttrFactory);
  // If attributes exist after struct contents, parse them.
  MaybeParseGNUAttributes(attrs, &LateFieldAttrs);

  // Late parse field attributes if necessary.
  ParseLexedCAttributeList(LateFieldAttrs, /*EnterScope=*/false);

  SmallVector<Decl *, 32> FieldDecls(TagDecl->fields());

  Actions.ActOnFields(getCurScope(), RecordLoc, TagDecl, FieldDecls,
                      T.getOpenLocation(), T.getCloseLocation(), attrs);
  StructScope.Exit();
  Actions.ActOnTagFinishDefinition(getCurScope(), TagDecl, T.getRange());
}

/// ParseEnumSpecifier
///       enum-specifier: [C99 6.7.2.2]
///         'enum' identifier[opt] '{' enumerator-list '}'
///[C99/C++]'enum' identifier[opt] '{' enumerator-list ',' '}'
/// [GNU]   'enum' attributes[opt] identifier[opt] '{' enumerator-list ',' [opt]
///                                                 '}' attributes[opt]
/// [MS]    'enum' __declspec[opt] identifier[opt] '{' enumerator-list ',' [opt]
///                                                 '}'
///         'enum' identifier
/// [GNU]   'enum' attributes[opt] identifier
///
/// [C++11] enum-head '{' enumerator-list[opt] '}'
/// [C++11] enum-head '{' enumerator-list ','  '}'
///
///       enum-head: [C++11]
///         enum-key attribute-specifier-seq[opt] identifier[opt] enum-base[opt]
///         enum-key attribute-specifier-seq[opt] nested-name-specifier
///             identifier enum-base[opt]
///
///       enum-key: [C++11]
///         'enum'
///         'enum' 'class'
///         'enum' 'struct'
///
///       enum-base: [C++11]
///         ':' type-specifier-seq
///
/// [C++] elaborated-type-specifier:
/// [C++]   'enum' nested-name-specifier[opt] identifier
///
void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
                                const ParsedTemplateInfo &TemplateInfo,
                                AccessSpecifier AS, DeclSpecContext DSC) {
  // Parse the tag portion of this.
  if (Tok.is(tok::code_completion)) {
    // Code completion for an enum name.
    cutOffParsing();
    Actions.CodeCompletion().CodeCompleteTag(getCurScope(), DeclSpec::TST_enum);
    DS.SetTypeSpecError(); // Needed by ActOnUsingDeclaration.
    return;
  }

  // If attributes exist after tag, parse them.
  ParsedAttributes attrs(AttrFactory);
  MaybeParseAttributes(PAKM_GNU | PAKM_Declspec | PAKM_CXX11, attrs);

  SourceLocation ScopedEnumKWLoc;
  bool IsScopedUsingClassTag = false;

  // In C++11, recognize 'enum class' and 'enum struct'.
  if (Tok.isOneOf(tok::kw_class, tok::kw_struct) && getLangOpts().CPlusPlus) {
    Diag(Tok, getLangOpts().CPlusPlus11 ? diag::warn_cxx98_compat_scoped_enum
                                        : diag::ext_scoped_enum);
    IsScopedUsingClassTag = Tok.is(tok::kw_class);
    ScopedEnumKWLoc = ConsumeToken();

    // Attributes are not allowed between these keywords.  Diagnose,
    // but then just treat them like they appeared in the right place.
    ProhibitAttributes(attrs);

    // They are allowed afterwards, though.
    MaybeParseAttributes(PAKM_GNU | PAKM_Declspec | PAKM_CXX11, attrs);
  }

  // C++11 [temp.explicit]p12:
  //   The usual access controls do not apply to names used to specify
  //   explicit instantiations.
  // We extend this to also cover explicit specializations.  Note that
  // we don't suppress if this turns out to be an elaborated type
  // specifier.
  bool shouldDelayDiagsInTag =
    (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation ||
     TemplateInfo.Kind == ParsedTemplateInfo::ExplicitSpecialization);
  SuppressAccessChecks diagsFromTag(*this, shouldDelayDiagsInTag);

  // Determine whether this declaration is permitted to have an enum-base.
  AllowDefiningTypeSpec AllowEnumSpecifier =
      isDefiningTypeSpecifierContext(DSC, getLangOpts().CPlusPlus);
  bool CanBeOpaqueEnumDeclaration =
      DS.isEmpty() && isOpaqueEnumDeclarationContext(DSC);
  bool CanHaveEnumBase = (getLangOpts().CPlusPlus11 || getLangOpts().ObjC ||
                          getLangOpts().MicrosoftExt) &&
                         (AllowEnumSpecifier == AllowDefiningTypeSpec::Yes ||
                          CanBeOpaqueEnumDeclaration);

  CXXScopeSpec &SS = DS.getTypeSpecScope();
  if (getLangOpts().CPlusPlus) {
    // "enum foo : bar;" is not a potential typo for "enum foo::bar;".
    ColonProtectionRAIIObject X(*this);

    CXXScopeSpec Spec;
    if (ParseOptionalCXXScopeSpecifier(Spec, /*ObjectType=*/nullptr,
                                       /*ObjectHasErrors=*/false,
                                       /*EnteringContext=*/true))
      return;

    if (Spec.isSet() && Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_expected) << tok::identifier;
      DS.SetTypeSpecError();
      if (Tok.isNot(tok::l_brace)) {
        // Has no name and is not a definition.
        // Skip the rest of this declarator, up until the comma or semicolon.
        SkipUntil(tok::comma, StopAtSemi);
        return;
      }
    }

    SS = Spec;
  }

  // Must have either 'enum name' or 'enum {...}' or (rarely) 'enum : T { ... }'.
  if (Tok.isNot(tok::identifier) && Tok.isNot(tok::l_brace) &&
      Tok.isNot(tok::colon)) {
    Diag(Tok, diag::err_expected_either) << tok::identifier << tok::l_brace;

    DS.SetTypeSpecError();
    // Skip the rest of this declarator, up until the comma or semicolon.
    SkipUntil(tok::comma, StopAtSemi);
    return;
  }

  // If an identifier is present, consume and remember it.
  IdentifierInfo *Name = nullptr;
  SourceLocation NameLoc;
  if (Tok.is(tok::identifier)) {
    Name = Tok.getIdentifierInfo();
    NameLoc = ConsumeToken();
  }

  if (!Name && ScopedEnumKWLoc.isValid()) {
    // C++0x 7.2p2: The optional identifier shall not be omitted in the
    // declaration of a scoped enumeration.
    Diag(Tok, diag::err_scoped_enum_missing_identifier);
    ScopedEnumKWLoc = SourceLocation();
    IsScopedUsingClassTag = false;
  }

  // Okay, end the suppression area.  We'll decide whether to emit the
  // diagnostics in a second.
  if (shouldDelayDiagsInTag)
    diagsFromTag.done();

  TypeResult BaseType;
  SourceRange BaseRange;

  bool CanBeBitfield =
      getCurScope()->isClassScope() && ScopedEnumKWLoc.isInvalid() && Name;

  // Parse the fixed underlying type.
  if (Tok.is(tok::colon)) {
    // This might be an enum-base or part of some unrelated enclosing context.
    //
    // 'enum E : base' is permitted in two circumstances:
    //
    // 1) As a defining-type-specifier, when followed by '{'.
    // 2) As the sole constituent of a complete declaration -- when DS is empty
    //    and the next token is ';'.
    //
    // The restriction to defining-type-specifiers is important to allow parsing
    //   a ? new enum E : int{}
    //   _Generic(a, enum E : int{})
    // properly.
    //
    // One additional consideration applies:
    //
    // C++ [dcl.enum]p1:
    //   A ':' following "enum nested-name-specifier[opt] identifier" within
    //   the decl-specifier-seq of a member-declaration is parsed as part of
    //   an enum-base.
    //
    // Other language modes supporting enumerations with fixed underlying types
    // do not have clear rules on this, so we disambiguate to determine whether
    // the tokens form a bit-field width or an enum-base.

    if (CanBeBitfield && !isEnumBase(CanBeOpaqueEnumDeclaration)) {
      // Outside C++11, do not interpret the tokens as an enum-base if they do
      // not make sense as one. In C++11, it's an error if this happens.
      if (getLangOpts().CPlusPlus11)
        Diag(Tok.getLocation(), diag::err_anonymous_enum_bitfield);
    } else if (CanHaveEnumBase || !ColonIsSacred) {
      SourceLocation ColonLoc = ConsumeToken();

      // Parse a type-specifier-seq as a type. We can't just ParseTypeName here,
      // because under -fms-extensions,
      //   enum E : int *p;
      // declares 'enum E : int; E *p;' not 'enum E : int*; E p;'.
      DeclSpec DS(AttrFactory);
      // enum-base is not assumed to be a type and therefore requires the
      // typename keyword [p0634r3].
      ParseSpecifierQualifierList(DS, ImplicitTypenameContext::No, AS,
                                  DeclSpecContext::DSC_type_specifier);
      Declarator DeclaratorInfo(DS, ParsedAttributesView::none(),
                                DeclaratorContext::TypeName);
      BaseType = Actions.ActOnTypeName(DeclaratorInfo);

      BaseRange = SourceRange(ColonLoc, DeclaratorInfo.getSourceRange().getEnd());

      if (!getLangOpts().ObjC && !getLangOpts().C23) {
        if (getLangOpts().CPlusPlus11)
          Diag(ColonLoc, diag::warn_cxx98_compat_enum_fixed_underlying_type)
              << BaseRange;
        else if (getLangOpts().CPlusPlus)
          Diag(ColonLoc, diag::ext_cxx11_enum_fixed_underlying_type)
              << BaseRange;
        else if (getLangOpts().MicrosoftExt)
          Diag(ColonLoc, diag::ext_ms_c_enum_fixed_underlying_type)
              << BaseRange;
        else
          Diag(ColonLoc, diag::ext_clang_c_enum_fixed_underlying_type)
              << BaseRange;
      }
    }
  }

  // There are four options here.  If we have 'friend enum foo;' then this is a
  // friend declaration, and cannot have an accompanying definition. If we have
  // 'enum foo;', then this is a forward declaration.  If we have
  // 'enum foo {...' then this is a definition. Otherwise we have something
  // like 'enum foo xyz', a reference.
  //
  // This is needed to handle stuff like this right (C99 6.7.2.3p11):
  // enum foo {..};  void bar() { enum foo; }    <- new foo in bar.
  // enum foo {..};  void bar() { enum foo x; }  <- use of old foo.
  //
  TagUseKind TUK;
  if (AllowEnumSpecifier == AllowDefiningTypeSpec::No)
    TUK = TagUseKind::Reference;
  else if (Tok.is(tok::l_brace)) {
    if (DS.isFriendSpecified()) {
      Diag(Tok.getLocation(), diag::err_friend_decl_defines_type)
        << SourceRange(DS.getFriendSpecLoc());
      ConsumeBrace();
      SkipUntil(tok::r_brace, StopAtSemi);
      // Discard any other definition-only pieces.
      attrs.clear();
      ScopedEnumKWLoc = SourceLocation();
      IsScopedUsingClassTag = false;
      BaseType = TypeResult();
      TUK = TagUseKind::Friend;
    } else {
      TUK = TagUseKind::Definition;
    }
  } else if (!isTypeSpecifier(DSC) &&
             (Tok.is(tok::semi) ||
              (Tok.isAtStartOfLine() &&
               !isValidAfterTypeSpecifier(CanBeBitfield)))) {
    // An opaque-enum-declaration is required to be standalone (no preceding or
    // following tokens in the declaration). Sema enforces this separately by
    // diagnosing anything else in the DeclSpec.
    TUK = DS.isFriendSpecified() ? TagUseKind::Friend : TagUseKind::Declaration;
    if (Tok.isNot(tok::semi)) {
      // A semicolon was missing after this declaration. Diagnose and recover.
      ExpectAndConsume(tok::semi, diag::err_expected_after, "enum");
      PP.EnterToken(Tok, /*IsReinject=*/true);
      Tok.setKind(tok::semi);
    }
  } else {
    TUK = TagUseKind::Reference;
  }

  bool IsElaboratedTypeSpecifier =
      TUK == TagUseKind::Reference || TUK == TagUseKind::Friend;

  // If this is an elaborated type specifier nested in a larger declaration,
  // and we delayed diagnostics before, just merge them into the current pool.
  if (TUK == TagUseKind::Reference && shouldDelayDiagsInTag) {
    diagsFromTag.redelay();
  }

  MultiTemplateParamsArg TParams;
  if (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
      TUK != TagUseKind::Reference) {
    if (!getLangOpts().CPlusPlus11 || !SS.isSet()) {
      // Skip the rest of this declarator, up until the comma or semicolon.
      Diag(Tok, diag::err_enum_template);
      SkipUntil(tok::comma, StopAtSemi);
      return;
    }

    if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
      // Enumerations can't be explicitly instantiated.
      DS.SetTypeSpecError();
      Diag(StartLoc, diag::err_explicit_instantiation_enum);
      return;
    }

    assert(TemplateInfo.TemplateParams && "no template parameters");
    TParams = MultiTemplateParamsArg(TemplateInfo.TemplateParams->data(),
                                     TemplateInfo.TemplateParams->size());
    SS.setTemplateParamLists(TParams);
  }

  if (!Name && TUK != TagUseKind::Definition) {
    Diag(Tok, diag::err_enumerator_unnamed_no_def);

    DS.SetTypeSpecError();
    // Skip the rest of this declarator, up until the comma or semicolon.
    SkipUntil(tok::comma, StopAtSemi);
    return;
  }

  // An elaborated-type-specifier has a much more constrained grammar:
  //
  //   'enum' nested-name-specifier[opt] identifier
  //
  // If we parsed any other bits, reject them now.
  //
  // MSVC and (for now at least) Objective-C permit a full enum-specifier
  // or opaque-enum-declaration anywhere.
  if (IsElaboratedTypeSpecifier && !getLangOpts().MicrosoftExt &&
      !getLangOpts().ObjC) {
    ProhibitCXX11Attributes(attrs, diag::err_attributes_not_allowed,
                            diag::err_keyword_not_allowed,
                            /*DiagnoseEmptyAttrs=*/true);
    if (BaseType.isUsable())
      Diag(BaseRange.getBegin(), diag::ext_enum_base_in_type_specifier)
          << (AllowEnumSpecifier == AllowDefiningTypeSpec::Yes) << BaseRange;
    else if (ScopedEnumKWLoc.isValid())
      Diag(ScopedEnumKWLoc, diag::ext_elaborated_enum_class)
        << FixItHint::CreateRemoval(ScopedEnumKWLoc) << IsScopedUsingClassTag;
  }

  stripTypeAttributesOffDeclSpec(attrs, DS, TUK);

  SkipBodyInfo SkipBody;
  if (!Name && TUK == TagUseKind::Definition && Tok.is(tok::l_brace) &&
      NextToken().is(tok::identifier))
    SkipBody = Actions.shouldSkipAnonEnumBody(getCurScope(),
                                              NextToken().getIdentifierInfo(),
                                              NextToken().getLocation());

  bool Owned = false;
  bool IsDependent = false;
  const char *PrevSpec = nullptr;
  unsigned DiagID;
  Decl *TagDecl =
      Actions.ActOnTag(getCurScope(), DeclSpec::TST_enum, TUK, StartLoc, SS,
                    Name, NameLoc, attrs, AS, DS.getModulePrivateSpecLoc(),
                    TParams, Owned, IsDependent, ScopedEnumKWLoc,
                    IsScopedUsingClassTag,
                    BaseType, DSC == DeclSpecContext::DSC_type_specifier,
                    DSC == DeclSpecContext::DSC_template_param ||
                        DSC == DeclSpecContext::DSC_template_type_arg,
                    OffsetOfState, &SkipBody).get();

  if (SkipBody.ShouldSkip) {
    assert(TUK == TagUseKind::Definition && "can only skip a definition");

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

    if (DS.SetTypeSpecType(DeclSpec::TST_enum, StartLoc,
                           NameLoc.isValid() ? NameLoc : StartLoc,
                           PrevSpec, DiagID, TagDecl, Owned,
                           Actions.getASTContext().getPrintingPolicy()))
      Diag(StartLoc, DiagID) << PrevSpec;
    return;
  }

  if (IsDependent) {
    // This enum has a dependent nested-name-specifier. Handle it as a
    // dependent tag.
    if (!Name) {
      DS.SetTypeSpecError();
      Diag(Tok, diag::err_expected_type_name_after_typename);
      return;
    }

    TypeResult Type = Actions.ActOnDependentTag(
        getCurScope(), DeclSpec::TST_enum, TUK, SS, Name, StartLoc, NameLoc);
    if (Type.isInvalid()) {
      DS.SetTypeSpecError();
      return;
    }

    if (DS.SetTypeSpecType(DeclSpec::TST_typename, StartLoc,
                           NameLoc.isValid() ? NameLoc : StartLoc,
                           PrevSpec, DiagID, Type.get(),
                           Actions.getASTContext().getPrintingPolicy()))
      Diag(StartLoc, DiagID) << PrevSpec;

    return;
  }

  if (!TagDecl) {
    // The action failed to produce an enumeration tag. If this is a
    // definition, consume the entire definition.
    if (Tok.is(tok::l_brace) && TUK != TagUseKind::Reference) {
      ConsumeBrace();
      SkipUntil(tok::r_brace, StopAtSemi);
    }

    DS.SetTypeSpecError();
    return;
  }

  if (Tok.is(tok::l_brace) && TUK == TagUseKind::Definition) {
    Decl *D = SkipBody.CheckSameAsPrevious ? SkipBody.New : TagDecl;
    ParseEnumBody(StartLoc, D);
    if (SkipBody.CheckSameAsPrevious &&
        !Actions.ActOnDuplicateDefinition(TagDecl, SkipBody)) {
      DS.SetTypeSpecError();
      return;
    }
  }

  if (DS.SetTypeSpecType(DeclSpec::TST_enum, StartLoc,
                         NameLoc.isValid() ? NameLoc : StartLoc,
                         PrevSpec, DiagID, TagDecl, Owned,
                         Actions.getASTContext().getPrintingPolicy()))
    Diag(StartLoc, DiagID) << PrevSpec;
}

/// ParseEnumBody - Parse a {} enclosed enumerator-list.
///       enumerator-list:
///         enumerator
///         enumerator-list ',' enumerator
///       enumerator:
///         enumeration-constant attributes[opt]
///         enumeration-constant attributes[opt] '=' constant-expression
///       enumeration-constant:
///         identifier
///
void Parser::ParseEnumBody(SourceLocation StartLoc, Decl *EnumDecl) {
  // Enter the scope of the enum body and start the definition.
  ParseScope EnumScope(this, Scope::DeclScope | Scope::EnumScope);
  Actions.ActOnTagStartDefinition(getCurScope(), EnumDecl);

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

  // C does not allow an empty enumerator-list, C++ does [dcl.enum].
  if (Tok.is(tok::r_brace) && !getLangOpts().CPlusPlus)
    Diag(Tok, diag::err_empty_enum);

  SmallVector<Decl *, 32> EnumConstantDecls;
  SmallVector<SuppressAccessChecks, 32> EnumAvailabilityDiags;

  Decl *LastEnumConstDecl = nullptr;

  // Parse the enumerator-list.
  while (Tok.isNot(tok::r_brace)) {
    // Parse enumerator. If failed, try skipping till the start of the next
    // enumerator definition.
    if (Tok.isNot(tok::identifier)) {
      Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
      if (SkipUntil(tok::comma, tok::r_brace, StopBeforeMatch) &&
          TryConsumeToken(tok::comma))
        continue;
      break;
    }
    IdentifierInfo *Ident = Tok.getIdentifierInfo();
    SourceLocation IdentLoc = ConsumeToken();

    // If attributes exist after the enumerator, parse them.
    ParsedAttributes attrs(AttrFactory);
    MaybeParseGNUAttributes(attrs);
    if (isAllowedCXX11AttributeSpecifier()) {
      if (getLangOpts().CPlusPlus)
        Diag(Tok.getLocation(), getLangOpts().CPlusPlus17
                                    ? diag::warn_cxx14_compat_ns_enum_attribute
                                    : diag::ext_ns_enum_attribute)
            << 1 /*enumerator*/;
      ParseCXX11Attributes(attrs);
    }

    SourceLocation EqualLoc;
    ExprResult AssignedVal;
    EnumAvailabilityDiags.emplace_back(*this);

    EnterExpressionEvaluationContext ConstantEvaluated(
        Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
    if (TryConsumeToken(tok::equal, EqualLoc)) {
      AssignedVal = ParseConstantExpressionInExprEvalContext();
      if (AssignedVal.isInvalid())
        SkipUntil(tok::comma, tok::r_brace, StopBeforeMatch);
    }

    // Install the enumerator constant into EnumDecl.
    Decl *EnumConstDecl = Actions.ActOnEnumConstant(
        getCurScope(), EnumDecl, LastEnumConstDecl, IdentLoc, Ident, attrs,
        EqualLoc, AssignedVal.get());
    EnumAvailabilityDiags.back().done();

    EnumConstantDecls.push_back(EnumConstDecl);
    LastEnumConstDecl = EnumConstDecl;

    if (Tok.is(tok::identifier)) {
      // We're missing a comma between enumerators.
      SourceLocation Loc = getEndOfPreviousToken();
      Diag(Loc, diag::err_enumerator_list_missing_comma)
        << FixItHint::CreateInsertion(Loc, ", ");
      continue;
    }

    // Emumerator definition must be finished, only comma or r_brace are
    // allowed here.
    SourceLocation CommaLoc;
    if (Tok.isNot(tok::r_brace) && !TryConsumeToken(tok::comma, CommaLoc)) {
      if (EqualLoc.isValid())
        Diag(Tok.getLocation(), diag::err_expected_either) << tok::r_brace
                                                           << tok::comma;
      else
        Diag(Tok.getLocation(), diag::err_expected_end_of_enumerator);
      if (SkipUntil(tok::comma, tok::r_brace, StopBeforeMatch)) {
        if (TryConsumeToken(tok::comma, CommaLoc))
          continue;
      } else {
        break;
      }
    }

    // If comma is followed by r_brace, emit appropriate warning.
    if (Tok.is(tok::r_brace) && CommaLoc.isValid()) {
      if (!getLangOpts().C99 && !getLangOpts().CPlusPlus11)
        Diag(CommaLoc, getLangOpts().CPlusPlus ?
               diag::ext_enumerator_list_comma_cxx :
               diag::ext_enumerator_list_comma_c)
          << FixItHint::CreateRemoval(CommaLoc);
      else if (getLangOpts().CPlusPlus11)
        Diag(CommaLoc, diag::warn_cxx98_compat_enumerator_list_comma)
          << FixItHint::CreateRemoval(CommaLoc);
      break;
    }
  }

  // Eat the }.
  T.consumeClose();

  // If attributes exist after the identifier list, parse them.
  ParsedAttributes attrs(AttrFactory);
  MaybeParseGNUAttributes(attrs);

  Actions.ActOnEnumBody(StartLoc, T.getRange(), EnumDecl, EnumConstantDecls,
                        getCurScope(), attrs);

  // Now handle enum constant availability diagnostics.
  assert(EnumConstantDecls.size() == EnumAvailabilityDiags.size());
  for (size_t i = 0, e = EnumConstantDecls.size(); i != e; ++i) {
    ParsingDeclRAIIObject PD(*this, ParsingDeclRAIIObject::NoParent);
    EnumAvailabilityDiags[i].redelay();
    PD.complete(EnumConstantDecls[i]);
  }

  EnumScope.Exit();
  Actions.ActOnTagFinishDefinition(getCurScope(), EnumDecl, T.getRange());

  // The next token must be valid after an enum definition. If not, a ';'
  // was probably forgotten.
  bool CanBeBitfield = getCurScope()->isClassScope();
  if (!isValidAfterTypeSpecifier(CanBeBitfield)) {
    ExpectAndConsume(tok::semi, diag::err_expected_after, "enum");
    // Push this token back into the preprocessor and change our current token
    // to ';' so that the rest of the code recovers as though there were an
    // ';' after the definition.
    PP.EnterToken(Tok, /*IsReinject=*/true);
    Tok.setKind(tok::semi);
  }
}

/// isKnownToBeTypeSpecifier - Return true if we know that the specified token
/// is definitely a type-specifier.  Return false if it isn't part of a type
/// specifier or if we're not sure.
bool Parser::isKnownToBeTypeSpecifier(const Token &Tok) const {
  switch (Tok.getKind()) {
  default: return false;
    // type-specifiers
  case tok::kw_short:
  case tok::kw_long:
  case tok::kw___int64:
  case tok::kw___int128:
  case tok::kw_signed:
  case tok::kw_unsigned:
  case tok::kw__Complex:
  case tok::kw__Imaginary:
  case tok::kw_void:
  case tok::kw_char:
  case tok::kw_wchar_t:
  case tok::kw_char8_t:
  case tok::kw_char16_t:
  case tok::kw_char32_t:
  case tok::kw_int:
  case tok::kw__ExtInt:
  case tok::kw__BitInt:
  case tok::kw___bf16:
  case tok::kw_half:
  case tok::kw_float:
  case tok::kw_double:
  case tok::kw__Accum:
  case tok::kw__Fract:
  case tok::kw__Float16:
  case tok::kw___float128:
  case tok::kw___ibm128:
  case tok::kw_bool:
  case tok::kw__Bool:
  case tok::kw__Decimal32:
  case tok::kw__Decimal64:
  case tok::kw__Decimal128:
  case tok::kw___vector:
#define GENERIC_IMAGE_TYPE(ImgType, Id) case tok::kw_##ImgType##_t:
#include "clang/Basic/OpenCLImageTypes.def"

    // struct-or-union-specifier (C99) or class-specifier (C++)
  case tok::kw_class:
  case tok::kw_struct:
  case tok::kw___interface:
  case tok::kw_union:
    // enum-specifier
  case tok::kw_enum:

    // typedef-name
  case tok::annot_typename:
    return true;
  }
}

/// isTypeSpecifierQualifier - Return true if the current token could be the
/// start of a specifier-qualifier-list.
bool Parser::isTypeSpecifierQualifier() {
  switch (Tok.getKind()) {
  default: return false;

  case tok::identifier:   // foo::bar
    if (TryAltiVecVectorToken())
      return true;
    [[fallthrough]];
  case tok::kw_typename:  // typename T::type
    // Annotate typenames and C++ scope specifiers.  If we get one, just
    // recurse to handle whatever we get.
    if (TryAnnotateTypeOrScopeToken())
      return true;
    if (Tok.is(tok::identifier))
      return false;
    return isTypeSpecifierQualifier();

  case tok::coloncolon:   // ::foo::bar
    if (NextToken().is(tok::kw_new) ||    // ::new
        NextToken().is(tok::kw_delete))   // ::delete
      return false;

    if (TryAnnotateTypeOrScopeToken())
      return true;
    return isTypeSpecifierQualifier();

    // GNU attributes support.
  case tok::kw___attribute:
    // C23/GNU typeof support.
  case tok::kw_typeof:
  case tok::kw_typeof_unqual:

    // type-specifiers
  case tok::kw_short:
  case tok::kw_long:
  case tok::kw___int64:
  case tok::kw___int128:
  case tok::kw_signed:
  case tok::kw_unsigned:
  case tok::kw__Complex:
  case tok::kw__Imaginary:
  case tok::kw_void:
  case tok::kw_char:
  case tok::kw_wchar_t:
  case tok::kw_char8_t:
  case tok::kw_char16_t:
  case tok::kw_char32_t:
  case tok::kw_int:
  case tok::kw__ExtInt:
  case tok::kw__BitInt:
  case tok::kw_half:
  case tok::kw___bf16:
  case tok::kw_float:
  case tok::kw_double:
  case tok::kw__Accum:
  case tok::kw__Fract:
  case tok::kw__Float16:
  case tok::kw___float128:
  case tok::kw___ibm128:
  case tok::kw_bool:
  case tok::kw__Bool:
  case tok::kw__Decimal32:
  case tok::kw__Decimal64:
  case tok::kw__Decimal128:
  case tok::kw___vector:
#define GENERIC_IMAGE_TYPE(ImgType, Id) case tok::kw_##ImgType##_t:
#include "clang/Basic/OpenCLImageTypes.def"

    // struct-or-union-specifier (C99) or class-specifier (C++)
  case tok::kw_class:
  case tok::kw_struct:
  case tok::kw___interface:
  case tok::kw_union:
    // enum-specifier
  case tok::kw_enum:

    // type-qualifier
  case tok::kw_const:
  case tok::kw_volatile:
  case tok::kw_restrict:
  case tok::kw__Sat:

    // Debugger support.
  case tok::kw___unknown_anytype:

    // typedef-name
  case tok::annot_typename:
    return true;

    // GNU ObjC bizarre protocol extension: <proto1,proto2> with implicit 'id'.
  case tok::less:
    return getLangOpts().ObjC;

  case tok::kw___cdecl:
  case tok::kw___stdcall:
  case tok::kw___fastcall:
  case tok::kw___thiscall:
  case tok::kw___regcall:
  case tok::kw___vectorcall:
  case tok::kw___w64:
  case tok::kw___ptr64:
  case tok::kw___ptr32:
  case tok::kw___pascal:
  case tok::kw___unaligned:

  case tok::kw__Nonnull:
  case tok::kw__Nullable:
  case tok::kw__Nullable_result:
  case tok::kw__Null_unspecified:

  case tok::kw___kindof:

  case tok::kw___private:
  case tok::kw___local:
  case tok::kw___global:
  case tok::kw___constant:
  case tok::kw___generic:
  case tok::kw___read_only:
  case tok::kw___read_write:
  case tok::kw___write_only:
  case tok::kw___funcref:
    return true;

  case tok::kw_private:
    return getLangOpts().OpenCL;

  // C11 _Atomic
  case tok::kw__Atomic:
    return true;

  // HLSL type qualifiers
  case tok::kw_groupshared:
  case tok::kw_in:
  case tok::kw_inout:
  case tok::kw_out:
    return getLangOpts().HLSL;
  }
}

Parser::DeclGroupPtrTy Parser::ParseTopLevelStmtDecl() {
  assert(PP.isIncrementalProcessingEnabled() && "Not in incremental mode");

  // Parse a top-level-stmt.
  Parser::StmtVector Stmts;
  ParsedStmtContext SubStmtCtx = ParsedStmtContext();
  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
                               Scope::CompoundStmtScope);
  TopLevelStmtDecl *TLSD = Actions.ActOnStartTopLevelStmtDecl(getCurScope());
  StmtResult R = ParseStatementOrDeclaration(Stmts, SubStmtCtx);
  if (!R.isUsable())
    return nullptr;

  Actions.ActOnFinishTopLevelStmtDecl(TLSD, R.get());

  if (Tok.is(tok::annot_repl_input_end) &&
      Tok.getAnnotationValue() != nullptr) {
    ConsumeAnnotationToken();
    TLSD->setSemiMissing();
  }

  SmallVector<Decl *, 2> DeclsInGroup;
  DeclsInGroup.push_back(TLSD);

  // Currently happens for things like -fms-extensions and use `__if_exists`.
  for (Stmt *S : Stmts) {
    // Here we should be safe as `__if_exists` and friends are not introducing
    // new variables which need to live outside file scope.
    TopLevelStmtDecl *D = Actions.ActOnStartTopLevelStmtDecl(getCurScope());
    Actions.ActOnFinishTopLevelStmtDecl(D, S);
    DeclsInGroup.push_back(D);
  }

  return Actions.BuildDeclaratorGroup(DeclsInGroup);
}

/// isDeclarationSpecifier() - Return true if the current token is part of a
/// declaration specifier.
///
/// \param AllowImplicitTypename whether this is a context where T::type [T
/// dependent] can appear.
/// \param DisambiguatingWithExpression True to indicate that the purpose of
/// this check is to disambiguate between an expression and a declaration.
bool Parser::isDeclarationSpecifier(
    ImplicitTypenameContext AllowImplicitTypename,
    bool DisambiguatingWithExpression) {
  switch (Tok.getKind()) {
  default: return false;

  // OpenCL 2.0 and later define this keyword.
  case tok::kw_pipe:
    return getLangOpts().OpenCL &&
           getLangOpts().getOpenCLCompatibleVersion() >= 200;

  case tok::identifier:   // foo::bar
    // Unfortunate hack to support "Class.factoryMethod" notation.
    if (getLangOpts().ObjC && NextToken().is(tok::period))
      return false;
    if (TryAltiVecVectorToken())
      return true;
    [[fallthrough]];
  case tok::kw_decltype: // decltype(T())::type
  case tok::kw_typename: // typename T::type
    // Annotate typenames and C++ scope specifiers.  If we get one, just
    // recurse to handle whatever we get.
    if (TryAnnotateTypeOrScopeToken(AllowImplicitTypename))
      return true;
    if (TryAnnotateTypeConstraint())
      return true;
    if (Tok.is(tok::identifier))
      return false;

    // If we're in Objective-C and we have an Objective-C class type followed
    // by an identifier and then either ':' or ']', in a place where an
    // expression is permitted, then this is probably a class message send
    // missing the initial '['. In this case, we won't consider this to be
    // the start of a declaration.
    if (DisambiguatingWithExpression &&
        isStartOfObjCClassMessageMissingOpenBracket())
      return false;

    return isDeclarationSpecifier(AllowImplicitTypename);

  case tok::coloncolon:   // ::foo::bar
    if (!getLangOpts().CPlusPlus)
      return false;
    if (NextToken().is(tok::kw_new) ||    // ::new
        NextToken().is(tok::kw_delete))   // ::delete
      return false;

    // Annotate typenames and C++ scope specifiers.  If we get one, just
    // recurse to handle whatever we get.
    if (TryAnnotateTypeOrScopeToken())
      return true;
    return isDeclarationSpecifier(ImplicitTypenameContext::No);

    // storage-class-specifier
  case tok::kw_typedef:
  case tok::kw_extern:
  case tok::kw___private_extern__:
  case tok::kw_static:
  case tok::kw_auto:
  case tok::kw___auto_type:
  case tok::kw_register:
  case tok::kw___thread:
  case tok::kw_thread_local:
  case tok::kw__Thread_local:

    // Modules
  case tok::kw___module_private__:

    // Debugger support
  case tok::kw___unknown_anytype:

    // type-specifiers
  case tok::kw_short:
  case tok::kw_long:
  case tok::kw___int64:
  case tok::kw___int128:
  case tok::kw_signed:
  case tok::kw_unsigned:
  case tok::kw__Complex:
  case tok::kw__Imaginary:
  case tok::kw_void:
  case tok::kw_char:
  case tok::kw_wchar_t:
  case tok::kw_char8_t:
  case tok::kw_char16_t:
  case tok::kw_char32_t:

  case tok::kw_int:
  case tok::kw__ExtInt:
  case tok::kw__BitInt:
  case tok::kw_half:
  case tok::kw___bf16:
  case tok::kw_float:
  case tok::kw_double:
  case tok::kw__Accum:
  case tok::kw__Fract:
  case tok::kw__Float16:
  case tok::kw___float128:
  case tok::kw___ibm128:
  case tok::kw_bool:
  case tok::kw__Bool:
  case tok::kw__Decimal32:
  case tok::kw__Decimal64:
  case tok::kw__Decimal128:
  case tok::kw___vector:

    // struct-or-union-specifier (C99) or class-specifier (C++)
  case tok::kw_class:
  case tok::kw_struct:
  case tok::kw_union:
  case tok::kw___interface:
    // enum-specifier
  case tok::kw_enum:

    // type-qualifier
  case tok::kw_const:
  case tok::kw_volatile:
  case tok::kw_restrict:
  case tok::kw__Sat:

    // function-specifier
  case tok::kw_inline:
  case tok::kw_virtual:
  case tok::kw_explicit:
  case tok::kw__Noreturn:

    // alignment-specifier
  case tok::kw__Alignas:

    // friend keyword.
  case tok::kw_friend:

    // static_assert-declaration
  case tok::kw_static_assert:
  case tok::kw__Static_assert:

    // C23/GNU typeof support.
  case tok::kw_typeof:
  case tok::kw_typeof_unqual:

    // GNU attributes.
  case tok::kw___attribute:

    // C++11 decltype and constexpr.
  case tok::annot_decltype:
  case tok::annot_pack_indexing_type:
  case tok::kw_constexpr:

    // C++20 consteval and constinit.
  case tok::kw_consteval:
  case tok::kw_constinit:

    // C11 _Atomic
  case tok::kw__Atomic:
    return true;

  case tok::kw_alignas:
    // alignas is a type-specifier-qualifier in C23, which is a kind of
    // declaration-specifier. Outside of C23 mode (including in C++), it is not.
    return getLangOpts().C23;

    // GNU ObjC bizarre protocol extension: <proto1,proto2> with implicit 'id'.
  case tok::less:
    return getLangOpts().ObjC;

    // typedef-name
  case tok::annot_typename:
    return !DisambiguatingWithExpression ||
           !isStartOfObjCClassMessageMissingOpenBracket();

    // placeholder-type-specifier
  case tok::annot_template_id: {
    TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
    if (TemplateId->hasInvalidName())
      return true;
    // FIXME: What about type templates that have only been annotated as
    // annot_template_id, not as annot_typename?
    return isTypeConstraintAnnotation() &&
           (NextToken().is(tok::kw_auto) || NextToken().is(tok::kw_decltype));
  }

  case tok::annot_cxxscope: {
    TemplateIdAnnotation *TemplateId =
        NextToken().is(tok::annot_template_id)
            ? takeTemplateIdAnnotation(NextToken())
            : nullptr;
    if (TemplateId && TemplateId->hasInvalidName())
      return true;
    // FIXME: What about type templates that have only been annotated as
    // annot_template_id, not as annot_typename?
    if (NextToken().is(tok::identifier) && TryAnnotateTypeConstraint())
      return true;
    return isTypeConstraintAnnotation() &&
        GetLookAheadToken(2).isOneOf(tok::kw_auto, tok::kw_decltype);
  }

  case tok::kw___declspec:
  case tok::kw___cdecl:
  case tok::kw___stdcall:
  case tok::kw___fastcall:
  case tok::kw___thiscall:
  case tok::kw___regcall:
  case tok::kw___vectorcall:
  case tok::kw___w64:
  case tok::kw___sptr:
  case tok::kw___uptr:
  case tok::kw___ptr64:
  case tok::kw___ptr32:
  case tok::kw___forceinline:
  case tok::kw___pascal:
  case tok::kw___unaligned:

  case tok::kw__Nonnull:
  case tok::kw__Nullable:
  case tok::kw__Nullable_result:
  case tok::kw__Null_unspecified:

  case tok::kw___kindof:

  case tok::kw___private:
  case tok::kw___local:
  case tok::kw___global:
  case tok::kw___constant:
  case tok::kw___generic:
  case tok::kw___read_only:
  case tok::kw___read_write:
  case tok::kw___write_only:
#define GENERIC_IMAGE_TYPE(ImgType, Id) case tok::kw_##ImgType##_t:
#include "clang/Basic/OpenCLImageTypes.def"

  case tok::kw___funcref:
  case tok::kw_groupshared:
    return true;

  case tok::kw_private:
    return getLangOpts().OpenCL;
  }
}

bool Parser::isConstructorDeclarator(bool IsUnqualified, bool DeductionGuide,
                                     DeclSpec::FriendSpecified IsFriend,
                                     const ParsedTemplateInfo *TemplateInfo) {
  RevertingTentativeParsingAction TPA(*this);
  // Parse the C++ scope specifier.
  CXXScopeSpec SS;
  if (TemplateInfo && TemplateInfo->TemplateParams)
    SS.setTemplateParamLists(*TemplateInfo->TemplateParams);

  if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
                                     /*ObjectHasErrors=*/false,
                                     /*EnteringContext=*/true)) {
    return false;
  }

  // Parse the constructor name.
  if (Tok.is(tok::identifier)) {
    // We already know that we have a constructor name; just consume
    // the token.
    ConsumeToken();
  } else if (Tok.is(tok::annot_template_id)) {
    ConsumeAnnotationToken();
  } else {
    return false;
  }

  // There may be attributes here, appertaining to the constructor name or type
  // we just stepped past.
  SkipCXX11Attributes();

  // Current class name must be followed by a left parenthesis.
  if (Tok.isNot(tok::l_paren)) {
    return false;
  }
  ConsumeParen();

  // A right parenthesis, or ellipsis followed by a right parenthesis signals
  // that we have a constructor.
  if (Tok.is(tok::r_paren) ||
      (Tok.is(tok::ellipsis) && NextToken().is(tok::r_paren))) {
    return true;
  }

  // A C++11 attribute here signals that we have a constructor, and is an
  // attribute on the first constructor parameter.
  if (getLangOpts().CPlusPlus11 &&
      isCXX11AttributeSpecifier(/*Disambiguate*/ false,
                                /*OuterMightBeMessageSend*/ true)) {
    return true;
  }

  // If we need to, enter the specified scope.
  DeclaratorScopeObj DeclScopeObj(*this, SS);
  if (SS.isSet() && Actions.ShouldEnterDeclaratorScope(getCurScope(), SS))
    DeclScopeObj.EnterDeclaratorScope();

  // Optionally skip Microsoft attributes.
  ParsedAttributes Attrs(AttrFactory);
  MaybeParseMicrosoftAttributes(Attrs);

  // Check whether the next token(s) are part of a declaration
  // specifier, in which case we have the start of a parameter and,
  // therefore, we know that this is a constructor.
  // Due to an ambiguity with implicit typename, the above is not enough.
  // Additionally, check to see if we are a friend.
  // If we parsed a scope specifier as well as friend,
  // we might be parsing a friend constructor.
  bool IsConstructor = false;
  ImplicitTypenameContext ITC = IsFriend && !SS.isSet()
                                    ? ImplicitTypenameContext::No
                                    : ImplicitTypenameContext::Yes;
  // Constructors cannot have this parameters, but we support that scenario here
  // to improve diagnostic.
  if (Tok.is(tok::kw_this)) {
    ConsumeToken();
    return isDeclarationSpecifier(ITC);
  }

  if (isDeclarationSpecifier(ITC))
    IsConstructor = true;
  else if (Tok.is(tok::identifier) ||
           (Tok.is(tok::annot_cxxscope) && NextToken().is(tok::identifier))) {
    // We've seen "C ( X" or "C ( X::Y", but "X" / "X::Y" is not a type.
    // This might be a parenthesized member name, but is more likely to
    // be a constructor declaration with an invalid argument type. Keep
    // looking.
    if (Tok.is(tok::annot_cxxscope))
      ConsumeAnnotationToken();
    ConsumeToken();

    // If this is not a constructor, we must be parsing a declarator,
    // which must have one of the following syntactic forms (see the
    // grammar extract at the start of ParseDirectDeclarator):
    switch (Tok.getKind()) {
    case tok::l_paren:
      // C(X   (   int));
    case tok::l_square:
      // C(X   [   5]);
      // C(X   [   [attribute]]);
    case tok::coloncolon:
      // C(X   ::   Y);
      // C(X   ::   *p);
      // Assume this isn't a constructor, rather than assuming it's a
      // constructor with an unnamed parameter of an ill-formed type.
      break;

    case tok::r_paren:
      // C(X   )

      // Skip past the right-paren and any following attributes to get to
      // the function body or trailing-return-type.
      ConsumeParen();
      SkipCXX11Attributes();

      if (DeductionGuide) {
        // C(X) -> ... is a deduction guide.
        IsConstructor = Tok.is(tok::arrow);
        break;
      }
      if (Tok.is(tok::colon) || Tok.is(tok::kw_try)) {
        // Assume these were meant to be constructors:
        //   C(X)   :    (the name of a bit-field cannot be parenthesized).
        //   C(X)   try  (this is otherwise ill-formed).
        IsConstructor = true;
      }
      if (Tok.is(tok::semi) || Tok.is(tok::l_brace)) {
        // If we have a constructor name within the class definition,
        // assume these were meant to be constructors:
        //   C(X)   {
        //   C(X)   ;
        // ... because otherwise we would be declaring a non-static data
        // member that is ill-formed because it's of the same type as its
        // surrounding class.
        //
        // FIXME: We can actually do this whether or not the name is qualified,
        // because if it is qualified in this context it must be being used as
        // a constructor name.
        // currently, so we're somewhat conservative here.
        IsConstructor = IsUnqualified;
      }
      break;

    default:
      IsConstructor = true;
      break;
    }
  }
  return IsConstructor;
}

/// ParseTypeQualifierListOpt
///          type-qualifier-list: [C99 6.7.5]
///            type-qualifier
/// [vendor]   attributes
///              [ only if AttrReqs & AR_VendorAttributesParsed ]
///            type-qualifier-list type-qualifier
/// [vendor]   type-qualifier-list attributes
///              [ only if AttrReqs & AR_VendorAttributesParsed ]
/// [C++0x]    attribute-specifier[opt] is allowed before cv-qualifier-seq
///              [ only if AttReqs & AR_CXX11AttributesParsed ]
/// Note: vendor can be GNU, MS, etc and can be explicitly controlled via
/// AttrRequirements bitmask values.
void Parser::ParseTypeQualifierListOpt(
    DeclSpec &DS, unsigned AttrReqs, bool AtomicAllowed,
    bool IdentifierRequired,
    std::optional<llvm::function_ref<void()>> CodeCompletionHandler) {
  if ((AttrReqs & AR_CXX11AttributesParsed) &&
      isAllowedCXX11AttributeSpecifier()) {
    ParsedAttributes Attrs(AttrFactory);
    ParseCXX11Attributes(Attrs);
    DS.takeAttributesFrom(Attrs);
  }

  SourceLocation EndLoc;

  while (true) {
    bool isInvalid = false;
    const char *PrevSpec = nullptr;
    unsigned DiagID = 0;
    SourceLocation Loc = Tok.getLocation();

    switch (Tok.getKind()) {
    case tok::code_completion:
      cutOffParsing();
      if (CodeCompletionHandler)
        (*CodeCompletionHandler)();
      else
        Actions.CodeCompletion().CodeCompleteTypeQualifiers(DS);
      return;

    case tok::kw_const:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_const   , Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw_volatile:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_volatile, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw_restrict:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_restrict, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw__Atomic:
      if (!AtomicAllowed)
        goto DoneWithTypeQuals;
      diagnoseUseOfC11Keyword(Tok);
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_atomic, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;

    // OpenCL qualifiers:
    case tok::kw_private:
      if (!getLangOpts().OpenCL)
        goto DoneWithTypeQuals;
      [[fallthrough]];
    case tok::kw___private:
    case tok::kw___global:
    case tok::kw___local:
    case tok::kw___constant:
    case tok::kw___generic:
    case tok::kw___read_only:
    case tok::kw___write_only:
    case tok::kw___read_write:
      ParseOpenCLQualifiers(DS.getAttributes());
      break;

    case tok::kw_groupshared:
    case tok::kw_in:
    case tok::kw_inout:
    case tok::kw_out:
      // NOTE: ParseHLSLQualifiers will consume the qualifier token.
      ParseHLSLQualifiers(DS.getAttributes());
      continue;

    case tok::kw___unaligned:
      isInvalid = DS.SetTypeQual(DeclSpec::TQ_unaligned, Loc, PrevSpec, DiagID,
                                 getLangOpts());
      break;
    case tok::kw___uptr:
      // GNU libc headers in C mode use '__uptr' as an identifier which conflicts
      // with the MS modifier keyword.
      if ((AttrReqs & AR_DeclspecAttributesParsed) && !getLangOpts().CPlusPlus &&
          IdentifierRequired && DS.isEmpty() && NextToken().is(tok::semi)) {
        if (TryKeywordIdentFallback(false))
          continue;
      }
      [[fallthrough]];
    case tok::kw___sptr:
    case tok::kw___w64:
    case tok::kw___ptr64:
    case tok::kw___ptr32:
    case tok::kw___cdecl:
    case tok::kw___stdcall:
    case tok::kw___fastcall:
    case tok::kw___thiscall:
    case tok::kw___regcall:
    case tok::kw___vectorcall:
      if (AttrReqs & AR_DeclspecAttributesParsed) {
        ParseMicrosoftTypeAttributes(DS.getAttributes());
        continue;
      }
      goto DoneWithTypeQuals;

    case tok::kw___funcref:
      ParseWebAssemblyFuncrefTypeAttribute(DS.getAttributes());
      continue;
      goto DoneWithTypeQuals;

    case tok::kw___pascal:
      if (AttrReqs & AR_VendorAttributesParsed) {
        ParseBorlandTypeAttributes(DS.getAttributes());
        continue;
      }
      goto DoneWithTypeQuals;

    // Nullability type specifiers.
    case tok::kw__Nonnull:
    case tok::kw__Nullable:
    case tok::kw__Nullable_result:
    case tok::kw__Null_unspecified:
      ParseNullabilityTypeSpecifiers(DS.getAttributes());
      continue;

    // Objective-C 'kindof' types.
    case tok::kw___kindof:
      DS.getAttributes().addNew(Tok.getIdentifierInfo(), Loc, nullptr, Loc,
                                nullptr, 0, tok::kw___kindof);
      (void)ConsumeToken();
      continue;

    case tok::kw___attribute:
      if (AttrReqs & AR_GNUAttributesParsedAndRejected)
        // When GNU attributes are expressly forbidden, diagnose their usage.
        Diag(Tok, diag::err_attributes_not_allowed);

      // Parse the attributes even if they are rejected to ensure that error
      // recovery is graceful.
      if (AttrReqs & AR_GNUAttributesParsed ||
          AttrReqs & AR_GNUAttributesParsedAndRejected) {
        ParseGNUAttributes(DS.getAttributes());
        continue; // do *not* consume the next token!
      }
      // otherwise, FALL THROUGH!
      [[fallthrough]];
    default:
      DoneWithTypeQuals:
      // If this is not a type-qualifier token, we're done reading type
      // qualifiers.  First verify that DeclSpec's are consistent.
      DS.Finish(Actions, Actions.getASTContext().getPrintingPolicy());
      if (EndLoc.isValid())
        DS.SetRangeEnd(EndLoc);
      return;
    }

    // If the specifier combination wasn't legal, issue a diagnostic.
    if (isInvalid) {
      assert(PrevSpec && "Method did not return previous specifier!");
      Diag(Tok, DiagID) << PrevSpec;
    }
    EndLoc = ConsumeToken();
  }
}

/// ParseDeclarator - Parse and verify a newly-initialized declarator.
void Parser::ParseDeclarator(Declarator &D) {
  /// This implements the 'declarator' production in the C grammar, then checks
  /// for well-formedness and issues diagnostics.
  Actions.runWithSufficientStackSpace(D.getBeginLoc(), [&] {
    ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);
  });
}

static bool isPtrOperatorToken(tok::TokenKind Kind, const LangOptions &Lang,
                               DeclaratorContext TheContext) {
  if (Kind == tok::star || Kind == tok::caret)
    return true;

  // OpenCL 2.0 and later define this keyword.
  if (Kind == tok::kw_pipe && Lang.OpenCL &&
      Lang.getOpenCLCompatibleVersion() >= 200)
    return true;

  if (!Lang.CPlusPlus)
    return false;

  if (Kind == tok::amp)
    return true;

  // We parse rvalue refs in C++03, because otherwise the errors are scary.
  // But we must not parse them in conversion-type-ids and new-type-ids, since
  // those can be legitimately followed by a && operator.
  // (The same thing can in theory happen after a trailing-return-type, but
  // since those are a C++11 feature, there is no rejects-valid issue there.)
  if (Kind == tok::ampamp)
    return Lang.CPlusPlus11 || (TheContext != DeclaratorContext::ConversionId &&
                                TheContext != DeclaratorContext::CXXNew);

  return false;
}

// Indicates whether the given declarator is a pipe declarator.
static bool isPipeDeclarator(const Declarator &D) {
  const unsigned NumTypes = D.getNumTypeObjects();

  for (unsigned Idx = 0; Idx != NumTypes; ++Idx)
    if (DeclaratorChunk::Pipe == D.getTypeObject(Idx).Kind)
      return true;

  return false;
}

/// ParseDeclaratorInternal - Parse a C or C++ declarator. The direct-declarator
/// is parsed by the function passed to it. Pass null, and the direct-declarator
/// isn't parsed at all, making this function effectively parse the C++
/// ptr-operator production.
///
/// If the grammar of this construct is extended, matching changes must also be
/// made to TryParseDeclarator and MightBeDeclarator, and possibly to
/// isConstructorDeclarator.
///
///       declarator: [C99 6.7.5] [C++ 8p4, dcl.decl]
/// [C]     pointer[opt] direct-declarator
/// [C++]   direct-declarator
/// [C++]   ptr-operator declarator
///
///       pointer: [C99 6.7.5]
///         '*' type-qualifier-list[opt]
///         '*' type-qualifier-list[opt] pointer
///
///       ptr-operator:
///         '*' cv-qualifier-seq[opt]
///         '&'
/// [C++0x] '&&'
/// [GNU]   '&' restrict[opt] attributes[opt]
/// [GNU?]  '&&' restrict[opt] attributes[opt]
///         '::'[opt] nested-name-specifier '*' cv-qualifier-seq[opt]
void Parser::ParseDeclaratorInternal(Declarator &D,
                                     DirectDeclParseFunction DirectDeclParser) {
  if (Diags.hasAllExtensionsSilenced())
    D.setExtension();

  // C++ member pointers start with a '::' or a nested-name.
  // Member pointers get special handling, since there's no place for the
  // scope spec in the generic path below.
  if (getLangOpts().CPlusPlus &&
      (Tok.is(tok::coloncolon) || Tok.is(tok::kw_decltype) ||
       (Tok.is(tok::identifier) &&
        (NextToken().is(tok::coloncolon) || NextToken().is(tok::less))) ||
       Tok.is(tok::annot_cxxscope))) {
    bool EnteringContext = D.getContext() == DeclaratorContext::File ||
                           D.getContext() == DeclaratorContext::Member;
    CXXScopeSpec SS;
    SS.setTemplateParamLists(D.getTemplateParameterLists());
    ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
                                   /*ObjectHasErrors=*/false, EnteringContext);

    if (SS.isNotEmpty()) {
      if (Tok.isNot(tok::star)) {
        // The scope spec really belongs to the direct-declarator.
        if (D.mayHaveIdentifier())
          D.getCXXScopeSpec() = SS;
        else
          AnnotateScopeToken(SS, true);

        if (DirectDeclParser)
          (this->*DirectDeclParser)(D);
        return;
      }

      if (SS.isValid()) {
        checkCompoundToken(SS.getEndLoc(), tok::coloncolon,
                           CompoundToken::MemberPtr);
      }

      SourceLocation StarLoc = ConsumeToken();
      D.SetRangeEnd(StarLoc);
      DeclSpec DS(AttrFactory);
      ParseTypeQualifierListOpt(DS);
      D.ExtendWithDeclSpec(DS);

      // Recurse to parse whatever is left.
      Actions.runWithSufficientStackSpace(D.getBeginLoc(), [&] {
        ParseDeclaratorInternal(D, DirectDeclParser);
      });

      // Sema will have to catch (syntactically invalid) pointers into global
      // scope. It has to catch pointers into namespace scope anyway.
      D.AddTypeInfo(DeclaratorChunk::getMemberPointer(
                        SS, DS.getTypeQualifiers(), StarLoc, DS.getEndLoc()),
                    std::move(DS.getAttributes()),
                    /* Don't replace range end. */ SourceLocation());
      return;
    }
  }

  tok::TokenKind Kind = Tok.getKind();

  if (D.getDeclSpec().isTypeSpecPipe() && !isPipeDeclarator(D)) {
    DeclSpec DS(AttrFactory);
    ParseTypeQualifierListOpt(DS);

    D.AddTypeInfo(
        DeclaratorChunk::getPipe(DS.getTypeQualifiers(), DS.getPipeLoc()),
        std::move(DS.getAttributes()), SourceLocation());
  }

  // Not a pointer, C++ reference, or block.
  if (!isPtrOperatorToken(Kind, getLangOpts(), D.getContext())) {
    if (DirectDeclParser)
      (this->*DirectDeclParser)(D);
    return;
  }

  // Otherwise, '*' -> pointer, '^' -> block, '&' -> lvalue reference,
  // '&&' -> rvalue reference
  SourceLocation Loc = ConsumeToken();  // Eat the *, ^, & or &&.
  D.SetRangeEnd(Loc);

  if (Kind == tok::star || Kind == tok::caret) {
    // Is a pointer.
    DeclSpec DS(AttrFactory);

    // GNU attributes are not allowed here in a new-type-id, but Declspec and
    // C++11 attributes are allowed.
    unsigned Reqs = AR_CXX11AttributesParsed | AR_DeclspecAttributesParsed |
                    ((D.getContext() != DeclaratorContext::CXXNew)
                         ? AR_GNUAttributesParsed
                         : AR_GNUAttributesParsedAndRejected);
    ParseTypeQualifierListOpt(DS, Reqs, true, !D.mayOmitIdentifier());
    D.ExtendWithDeclSpec(DS);

    // Recursively parse the declarator.
    Actions.runWithSufficientStackSpace(
        D.getBeginLoc(), [&] { ParseDeclaratorInternal(D, DirectDeclParser); });
    if (Kind == tok::star)
      // Remember that we parsed a pointer type, and remember the type-quals.
      D.AddTypeInfo(DeclaratorChunk::getPointer(
                        DS.getTypeQualifiers(), Loc, DS.getConstSpecLoc(),
                        DS.getVolatileSpecLoc(), DS.getRestrictSpecLoc(),
                        DS.getAtomicSpecLoc(), DS.getUnalignedSpecLoc()),
                    std::move(DS.getAttributes()), SourceLocation());
    else
      // Remember that we parsed a Block type, and remember the type-quals.
      D.AddTypeInfo(
          DeclaratorChunk::getBlockPointer(DS.getTypeQualifiers(), Loc),
          std::move(DS.getAttributes()), SourceLocation());
  } else {
    // Is a reference
    DeclSpec DS(AttrFactory);

    // Complain about rvalue references in C++03, but then go on and build
    // the declarator.
    if (Kind == tok::ampamp)
      Diag(Loc, getLangOpts().CPlusPlus11 ?
           diag::warn_cxx98_compat_rvalue_reference :
           diag::ext_rvalue_reference);

    // GNU-style and C++11 attributes are allowed here, as is restrict.
    ParseTypeQualifierListOpt(DS);
    D.ExtendWithDeclSpec(DS);

    // C++ 8.3.2p1: cv-qualified references are ill-formed except when the
    // cv-qualifiers are introduced through the use of a typedef or of a
    // template type argument, in which case the cv-qualifiers are ignored.
    if (DS.getTypeQualifiers() != DeclSpec::TQ_unspecified) {
      if (DS.getTypeQualifiers() & DeclSpec::TQ_const)
        Diag(DS.getConstSpecLoc(),
             diag::err_invalid_reference_qualifier_application) << "const";
      if (DS.getTypeQualifiers() & DeclSpec::TQ_volatile)
        Diag(DS.getVolatileSpecLoc(),
             diag::err_invalid_reference_qualifier_application) << "volatile";
      // 'restrict' is permitted as an extension.
      if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
        Diag(DS.getAtomicSpecLoc(),
             diag::err_invalid_reference_qualifier_application) << "_Atomic";
    }

    // Recursively parse the declarator.
    Actions.runWithSufficientStackSpace(
        D.getBeginLoc(), [&] { ParseDeclaratorInternal(D, DirectDeclParser); });

    if (D.getNumTypeObjects() > 0) {
      // C++ [dcl.ref]p4: There shall be no references to references.
      DeclaratorChunk& InnerChunk = D.getTypeObject(D.getNumTypeObjects() - 1);
      if (InnerChunk.Kind == DeclaratorChunk::Reference) {
        if (const IdentifierInfo *II = D.getIdentifier())
          Diag(InnerChunk.Loc, diag::err_illegal_decl_reference_to_reference)
           << II;
        else
          Diag(InnerChunk.Loc, diag::err_illegal_decl_reference_to_reference)
            << "type name";

        // Once we've complained about the reference-to-reference, we
        // can go ahead and build the (technically ill-formed)
        // declarator: reference collapsing will take care of it.
      }
    }

    // Remember that we parsed a reference type.
    D.AddTypeInfo(DeclaratorChunk::getReference(DS.getTypeQualifiers(), Loc,
                                                Kind == tok::amp),
                  std::move(DS.getAttributes()), SourceLocation());
  }
}

// When correcting from misplaced brackets before the identifier, the location
// is saved inside the declarator so that other diagnostic messages can use
// them.  This extracts and returns that location, or returns the provided
// location if a stored location does not exist.
static SourceLocation getMissingDeclaratorIdLoc(Declarator &D,
                                                SourceLocation Loc) {
  if (D.getName().StartLocation.isInvalid() &&
      D.getName().EndLocation.isValid())
    return D.getName().EndLocation;

  return Loc;
}

/// ParseDirectDeclarator
///       direct-declarator: [C99 6.7.5]
/// [C99]   identifier
///         '(' declarator ')'
/// [GNU]   '(' attributes declarator ')'
/// [C90]   direct-declarator '[' constant-expression[opt] ']'
/// [C99]   direct-declarator '[' type-qual-list[opt] assignment-expr[opt] ']'
/// [C99]   direct-declarator '[' 'static' type-qual-list[opt] assign-expr ']'
/// [C99]   direct-declarator '[' type-qual-list 'static' assignment-expr ']'
/// [C99]   direct-declarator '[' type-qual-list[opt] '*' ']'
/// [C++11] direct-declarator '[' constant-expression[opt] ']'
///                    attribute-specifier-seq[opt]
///         direct-declarator '(' parameter-type-list ')'
///         direct-declarator '(' identifier-list[opt] ')'
/// [GNU]   direct-declarator '(' parameter-forward-declarations
///                    parameter-type-list[opt] ')'
/// [C++]   direct-declarator '(' parameter-declaration-clause ')'
///                    cv-qualifier-seq[opt] exception-specification[opt]
/// [C++11] direct-declarator '(' parameter-declaration-clause ')'
///                    attribute-specifier-seq[opt] cv-qualifier-seq[opt]
///                    ref-qualifier[opt] exception-specification[opt]
/// [C++]   declarator-id
/// [C++11] declarator-id attribute-specifier-seq[opt]
///
///       declarator-id: [C++ 8]
///         '...'[opt] id-expression
///         '::'[opt] nested-name-specifier[opt] type-name
///
///       id-expression: [C++ 5.1]
///         unqualified-id
///         qualified-id
///
///       unqualified-id: [C++ 5.1]
///         identifier
///         operator-function-id
///         conversion-function-id
///          '~' class-name
///         template-id
///
/// C++17 adds the following, which we also handle here:
///
///       simple-declaration:
///         <decl-spec> '[' identifier-list ']' brace-or-equal-initializer ';'
///
/// Note, any additional constructs added here may need corresponding changes
/// in isConstructorDeclarator.
void Parser::ParseDirectDeclarator(Declarator &D) {
  DeclaratorScopeObj DeclScopeObj(*this, D.getCXXScopeSpec());

  if (getLangOpts().CPlusPlus && D.mayHaveIdentifier()) {
    // This might be a C++17 structured binding.
    if (Tok.is(tok::l_square) && !D.mayOmitIdentifier() &&
        D.getCXXScopeSpec().isEmpty())
      return ParseDecompositionDeclarator(D);

    // Don't parse FOO:BAR as if it were a typo for FOO::BAR inside a class, in
    // this context it is a bitfield. Also in range-based for statement colon
    // may delimit for-range-declaration.
    ColonProtectionRAIIObject X(
        *this, D.getContext() == DeclaratorContext::Member ||
                   (D.getContext() == DeclaratorContext::ForInit &&
                    getLangOpts().CPlusPlus11));

    // ParseDeclaratorInternal might already have parsed the scope.
    if (D.getCXXScopeSpec().isEmpty()) {
      bool EnteringContext = D.getContext() == DeclaratorContext::File ||
                             D.getContext() == DeclaratorContext::Member;
      ParseOptionalCXXScopeSpecifier(
          D.getCXXScopeSpec(), /*ObjectType=*/nullptr,
          /*ObjectHasErrors=*/false, EnteringContext);
    }

    // C++23 [basic.scope.namespace]p1:
    //   For each non-friend redeclaration or specialization whose target scope
    //   is or is contained by the scope, the portion after the declarator-id,
    //   class-head-name, or enum-head-name is also included in the scope.
    // C++23 [basic.scope.class]p1:
    //   For each non-friend redeclaration or specialization whose target scope
    //   is or is contained by the scope, the portion after the declarator-id,
    //   class-head-name, or enum-head-name is also included in the scope.
    //
    // FIXME: We should not be doing this for friend declarations; they have
    // their own special lookup semantics specified by [basic.lookup.unqual]p6.
    if (D.getCXXScopeSpec().isValid()) {
      if (Actions.ShouldEnterDeclaratorScope(getCurScope(),
                                             D.getCXXScopeSpec()))
        // Change the declaration context for name lookup, until this function
        // is exited (and the declarator has been parsed).
        DeclScopeObj.EnterDeclaratorScope();
      else if (getObjCDeclContext()) {
        // Ensure that we don't interpret the next token as an identifier when
        // dealing with declarations in an Objective-C container.
        D.SetIdentifier(nullptr, Tok.getLocation());
        D.setInvalidType(true);
        ConsumeToken();
        goto PastIdentifier;
      }
    }

    // C++0x [dcl.fct]p14:
    //   There is a syntactic ambiguity when an ellipsis occurs at the end of a
    //   parameter-declaration-clause without a preceding comma. In this case,
    //   the ellipsis is parsed as part of the abstract-declarator if the type
    //   of the parameter either names a template parameter pack that has not
    //   been expanded or contains auto; otherwise, it is parsed as part of the
    //   parameter-declaration-clause.
    if (Tok.is(tok::ellipsis) && D.getCXXScopeSpec().isEmpty() &&
        !((D.getContext() == DeclaratorContext::Prototype ||
           D.getContext() == DeclaratorContext::LambdaExprParameter ||
           D.getContext() == DeclaratorContext::BlockLiteral) &&
          NextToken().is(tok::r_paren) && !D.hasGroupingParens() &&
          !Actions.containsUnexpandedParameterPacks(D) &&
          D.getDeclSpec().getTypeSpecType() != TST_auto)) {
      SourceLocation EllipsisLoc = ConsumeToken();
      if (isPtrOperatorToken(Tok.getKind(), getLangOpts(), D.getContext())) {
        // The ellipsis was put in the wrong place. Recover, and explain to
        // the user what they should have done.
        ParseDeclarator(D);
        if (EllipsisLoc.isValid())
          DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, D);
        return;
      } else
        D.setEllipsisLoc(EllipsisLoc);

      // The ellipsis can't be followed by a parenthesized declarator. We
      // check for that in ParseParenDeclarator, after we have disambiguated
      // the l_paren token.
    }

    if (Tok.isOneOf(tok::identifier, tok::kw_operator, tok::annot_template_id,
                    tok::tilde)) {
      // We found something that indicates the start of an unqualified-id.
      // Parse that unqualified-id.
      bool AllowConstructorName;
      bool AllowDeductionGuide;
      if (D.getDeclSpec().hasTypeSpecifier()) {
        AllowConstructorName = false;
        AllowDeductionGuide = false;
      } else if (D.getCXXScopeSpec().isSet()) {
        AllowConstructorName = (D.getContext() == DeclaratorContext::File ||
                                D.getContext() == DeclaratorContext::Member);
        AllowDeductionGuide = false;
      } else {
        AllowConstructorName = (D.getContext() == DeclaratorContext::Member);
        AllowDeductionGuide = (D.getContext() == DeclaratorContext::File ||
                               D.getContext() == DeclaratorContext::Member);
      }

      bool HadScope = D.getCXXScopeSpec().isValid();
      SourceLocation TemplateKWLoc;
      if (ParseUnqualifiedId(D.getCXXScopeSpec(),
                             /*ObjectType=*/nullptr,
                             /*ObjectHadErrors=*/false,
                             /*EnteringContext=*/true,
                             /*AllowDestructorName=*/true, AllowConstructorName,
                             AllowDeductionGuide, &TemplateKWLoc,
                             D.getName()) ||
          // Once we're past the identifier, if the scope was bad, mark the
          // whole declarator bad.
          D.getCXXScopeSpec().isInvalid()) {
        D.SetIdentifier(nullptr, Tok.getLocation());
        D.setInvalidType(true);
      } else {
        // ParseUnqualifiedId might have parsed a scope specifier during error
        // recovery. If it did so, enter that scope.
        if (!HadScope && D.getCXXScopeSpec().isValid() &&
            Actions.ShouldEnterDeclaratorScope(getCurScope(),
                                               D.getCXXScopeSpec()))
          DeclScopeObj.EnterDeclaratorScope();

        // Parsed the unqualified-id; update range information and move along.
        if (D.getSourceRange().getBegin().isInvalid())
          D.SetRangeBegin(D.getName().getSourceRange().getBegin());
        D.SetRangeEnd(D.getName().getSourceRange().getEnd());
      }
      goto PastIdentifier;
    }

    if (D.getCXXScopeSpec().isNotEmpty()) {
      // We have a scope specifier but no following unqualified-id.
      Diag(PP.getLocForEndOfToken(D.getCXXScopeSpec().getEndLoc()),
           diag::err_expected_unqualified_id)
          << /*C++*/1;
      D.SetIdentifier(nullptr, Tok.getLocation());
      goto PastIdentifier;
    }
  } else if (Tok.is(tok::identifier) && D.mayHaveIdentifier()) {
    assert(!getLangOpts().CPlusPlus &&
           "There's a C++-specific check for tok::identifier above");
    assert(Tok.getIdentifierInfo() && "Not an identifier?");
    D.SetIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
    D.SetRangeEnd(Tok.getLocation());
    ConsumeToken();
    goto PastIdentifier;
  } else if (Tok.is(tok::identifier) && !D.mayHaveIdentifier()) {
    // We're not allowed an identifier here, but we got one. Try to figure out
    // if the user was trying to attach a name to the type, or whether the name
    // is some unrelated trailing syntax.
    bool DiagnoseIdentifier = false;
    if (D.hasGroupingParens())
      // An identifier within parens is unlikely to be intended to be anything
      // other than a name being "declared".
      DiagnoseIdentifier = true;
    else if (D.getContext() == DeclaratorContext::TemplateArg)
      // T<int N> is an accidental identifier; T<int N indicates a missing '>'.
      DiagnoseIdentifier =
          NextToken().isOneOf(tok::comma, tok::greater, tok::greatergreater);
    else if (D.getContext() == DeclaratorContext::AliasDecl ||
             D.getContext() == DeclaratorContext::AliasTemplate)
      // The most likely error is that the ';' was forgotten.
      DiagnoseIdentifier = NextToken().isOneOf(tok::comma, tok::semi);
    else if ((D.getContext() == DeclaratorContext::TrailingReturn ||
              D.getContext() == DeclaratorContext::TrailingReturnVar) &&
             !isCXX11VirtSpecifier(Tok))
      DiagnoseIdentifier = NextToken().isOneOf(
          tok::comma, tok::semi, tok::equal, tok::l_brace, tok::kw_try);
    if (DiagnoseIdentifier) {
      Diag(Tok.getLocation(), diag::err_unexpected_unqualified_id)
        << FixItHint::CreateRemoval(Tok.getLocation());
      D.SetIdentifier(nullptr, Tok.getLocation());
      ConsumeToken();
      goto PastIdentifier;
    }
  }

  if (Tok.is(tok::l_paren)) {
    // If this might be an abstract-declarator followed by a direct-initializer,
    // check whether this is a valid declarator chunk. If it can't be, assume
    // that it's an initializer instead.
    if (D.mayOmitIdentifier() && D.mayBeFollowedByCXXDirectInit()) {
      RevertingTentativeParsingAction PA(*this);
      if (TryParseDeclarator(true, D.mayHaveIdentifier(), true,
                             D.getDeclSpec().getTypeSpecType() == TST_auto) ==
          TPResult::False) {
        D.SetIdentifier(nullptr, Tok.getLocation());
        goto PastIdentifier;
      }
    }

    // direct-declarator: '(' declarator ')'
    // direct-declarator: '(' attributes declarator ')'
    // Example: 'char (*X)'   or 'int (*XX)(void)'
    ParseParenDeclarator(D);

    // If the declarator was parenthesized, we entered the declarator
    // scope when parsing the parenthesized declarator, then exited
    // the scope already. Re-enter the scope, if we need to.
    if (D.getCXXScopeSpec().isSet()) {
      // If there was an error parsing parenthesized declarator, declarator
      // scope may have been entered before. Don't do it again.
      if (!D.isInvalidType() &&
          Actions.ShouldEnterDeclaratorScope(getCurScope(),
                                             D.getCXXScopeSpec()))
        // Change the declaration context for name lookup, until this function
        // is exited (and the declarator has been parsed).
        DeclScopeObj.EnterDeclaratorScope();
    }
  } else if (D.mayOmitIdentifier()) {
    // This could be something simple like "int" (in which case the declarator
    // portion is empty), if an abstract-declarator is allowed.
    D.SetIdentifier(nullptr, Tok.getLocation());

    // The grammar for abstract-pack-declarator does not allow grouping parens.
    // FIXME: Revisit this once core issue 1488 is resolved.
    if (D.hasEllipsis() && D.hasGroupingParens())
      Diag(PP.getLocForEndOfToken(D.getEllipsisLoc()),
           diag::ext_abstract_pack_declarator_parens);
  } else {
    if (Tok.getKind() == tok::annot_pragma_parser_crash)
      LLVM_BUILTIN_TRAP;
    if (Tok.is(tok::l_square))
      return ParseMisplacedBracketDeclarator(D);
    if (D.getContext() == DeclaratorContext::Member) {
      // Objective-C++: Detect C++ keywords and try to prevent further errors by
      // treating these keyword as valid member names.
      if (getLangOpts().ObjC && getLangOpts().CPlusPlus &&
          !Tok.isAnnotation() && Tok.getIdentifierInfo() &&
          Tok.getIdentifierInfo()->isCPlusPlusKeyword(getLangOpts())) {
        Diag(getMissingDeclaratorIdLoc(D, Tok.getLocation()),
             diag::err_expected_member_name_or_semi_objcxx_keyword)
            << Tok.getIdentifierInfo()
            << (D.getDeclSpec().isEmpty() ? SourceRange()
                                          : D.getDeclSpec().getSourceRange());
        D.SetIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
        D.SetRangeEnd(Tok.getLocation());
        ConsumeToken();
        goto PastIdentifier;
      }
      Diag(getMissingDeclaratorIdLoc(D, Tok.getLocation()),
           diag::err_expected_member_name_or_semi)
          << (D.getDeclSpec().isEmpty() ? SourceRange()
                                        : D.getDeclSpec().getSourceRange());
    } else {
      if (Tok.getKind() == tok::TokenKind::kw_while) {
        Diag(Tok, diag::err_while_loop_outside_of_a_function);
      } else if (getLangOpts().CPlusPlus) {
        if (Tok.isOneOf(tok::period, tok::arrow))
          Diag(Tok, diag::err_invalid_operator_on_type) << Tok.is(tok::arrow);
        else {
          SourceLocation Loc = D.getCXXScopeSpec().getEndLoc();
          if (Tok.isAtStartOfLine() && Loc.isValid())
            Diag(PP.getLocForEndOfToken(Loc), diag::err_expected_unqualified_id)
                << getLangOpts().CPlusPlus;
          else
            Diag(getMissingDeclaratorIdLoc(D, Tok.getLocation()),
                 diag::err_expected_unqualified_id)
                << getLangOpts().CPlusPlus;
        }
      } else {
        Diag(getMissingDeclaratorIdLoc(D, Tok.getLocation()),
             diag::err_expected_either)
            << tok::identifier << tok::l_paren;
      }
    }
    D.SetIdentifier(nullptr, Tok.getLocation());
    D.setInvalidType(true);
  }

 PastIdentifier:
  assert(D.isPastIdentifier() &&
         "Haven't past the location of the identifier yet?");

  // Don't parse attributes unless we have parsed an unparenthesized name.
  if (D.hasName() && !D.getNumTypeObjects())
    MaybeParseCXX11Attributes(D);

  while (true) {
    if (Tok.is(tok::l_paren)) {
      bool IsFunctionDeclaration = D.isFunctionDeclaratorAFunctionDeclaration();
      // Enter function-declaration scope, limiting any declarators to the
      // function prototype scope, including parameter declarators.
      ParseScope PrototypeScope(this,
                                Scope::FunctionPrototypeScope|Scope::DeclScope|
                                (IsFunctionDeclaration
                                   ? Scope::FunctionDeclarationScope : 0));

      // The paren may be part of a C++ direct initializer, eg. "int x(1);".
      // In such a case, check if we actually have a function declarator; if it
      // is not, the declarator has been fully parsed.
      bool IsAmbiguous = false;
      if (getLangOpts().CPlusPlus && D.mayBeFollowedByCXXDirectInit()) {
        // C++2a [temp.res]p5
        // A qualified-id is assumed to name a type if
        //   - [...]
        //   - it is a decl-specifier of the decl-specifier-seq of a
        //     - [...]
        //     - parameter-declaration in a member-declaration [...]
        //     - parameter-declaration in a declarator of a function or function
        //       template declaration whose declarator-id is qualified [...]
        auto AllowImplicitTypename = ImplicitTypenameContext::No;
        if (D.getCXXScopeSpec().isSet())
          AllowImplicitTypename =
              (ImplicitTypenameContext)Actions.isDeclaratorFunctionLike(D);
        else if (D.getContext() == DeclaratorContext::Member) {
          AllowImplicitTypename = ImplicitTypenameContext::Yes;
        }

        // The name of the declarator, if any, is tentatively declared within
        // a possible direct initializer.
        TentativelyDeclaredIdentifiers.push_back(D.getIdentifier());
        bool IsFunctionDecl =
            isCXXFunctionDeclarator(&IsAmbiguous, AllowImplicitTypename);
        TentativelyDeclaredIdentifiers.pop_back();
        if (!IsFunctionDecl)
          break;
      }
      ParsedAttributes attrs(AttrFactory);
      BalancedDelimiterTracker T(*this, tok::l_paren);
      T.consumeOpen();
      if (IsFunctionDeclaration)
        Actions.ActOnStartFunctionDeclarationDeclarator(D,
                                                        TemplateParameterDepth);
      ParseFunctionDeclarator(D, attrs, T, IsAmbiguous);
      if (IsFunctionDeclaration)
        Actions.ActOnFinishFunctionDeclarationDeclarator(D);
      PrototypeScope.Exit();
    } else if (Tok.is(tok::l_square)) {
      ParseBracketDeclarator(D);
    } else if (Tok.isRegularKeywordAttribute()) {
      // For consistency with attribute parsing.
      Diag(Tok, diag::err_keyword_not_allowed) << Tok.getIdentifierInfo();
      bool TakesArgs = doesKeywordAttributeTakeArgs(Tok.getKind());
      ConsumeToken();
      if (TakesArgs) {
        BalancedDelimiterTracker T(*this, tok::l_paren);
        if (!T.consumeOpen())
          T.skipToEnd();
      }
    } else if (Tok.is(tok::kw_requires) && D.hasGroupingParens()) {
      // This declarator is declaring a function, but the requires clause is
      // in the wrong place:
      //   void (f() requires true);
      // instead of
      //   void f() requires true;
      // or
      //   void (f()) requires true;
      Diag(Tok, diag::err_requires_clause_inside_parens);
      ConsumeToken();
      ExprResult TrailingRequiresClause = Actions.CorrectDelayedTyposInExpr(
         ParseConstraintLogicalOrExpression(/*IsTrailingRequiresClause=*/true));
      if (TrailingRequiresClause.isUsable() && D.isFunctionDeclarator() &&
          !D.hasTrailingRequiresClause())
        // We're already ill-formed if we got here but we'll accept it anyway.
        D.setTrailingRequiresClause(TrailingRequiresClause.get());
    } else {
      break;
    }
  }
}

void Parser::ParseDecompositionDeclarator(Declarator &D) {
  assert(Tok.is(tok::l_square));

  TentativeParsingAction PA(*this);
  BalancedDelimiterTracker T(*this, tok::l_square);
  T.consumeOpen();

  if (isCXX11AttributeSpecifier())
    DiagnoseAndSkipCXX11Attributes();

  // If this doesn't look like a structured binding, maybe it's a misplaced
  // array declarator.
  if (!(Tok.is(tok::identifier) &&
        NextToken().isOneOf(tok::comma, tok::r_square, tok::kw_alignas,
                            tok::l_square)) &&
      !(Tok.is(tok::r_square) &&
        NextToken().isOneOf(tok::equal, tok::l_brace))) {
    PA.Revert();
    return ParseMisplacedBracketDeclarator(D);
  }

  SmallVector<DecompositionDeclarator::Binding, 32> Bindings;
  while (Tok.isNot(tok::r_square)) {
    if (!Bindings.empty()) {
      if (Tok.is(tok::comma))
        ConsumeToken();
      else {
        if (Tok.is(tok::identifier)) {
          SourceLocation EndLoc = getEndOfPreviousToken();
          Diag(EndLoc, diag::err_expected)
              << tok::comma << FixItHint::CreateInsertion(EndLoc, ",");
        } else {
          Diag(Tok, diag::err_expected_comma_or_rsquare);
        }

        SkipUntil(tok::r_square, tok::comma, tok::identifier,
                  StopAtSemi | StopBeforeMatch);
        if (Tok.is(tok::comma))
          ConsumeToken();
        else if (Tok.isNot(tok::identifier))
          break;
      }
    }

    if (isCXX11AttributeSpecifier())
      DiagnoseAndSkipCXX11Attributes();

    if (Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_expected) << tok::identifier;
      break;
    }

    IdentifierInfo *II = Tok.getIdentifierInfo();
    SourceLocation Loc = Tok.getLocation();
    ConsumeToken();

    ParsedAttributes Attrs(AttrFactory);
    if (isCXX11AttributeSpecifier()) {
      Diag(Tok, getLangOpts().CPlusPlus26
                    ? diag::warn_cxx23_compat_decl_attrs_on_binding
                    : diag::ext_decl_attrs_on_binding);
      MaybeParseCXX11Attributes(Attrs);
    }

    Bindings.push_back({II, Loc, std::move(Attrs)});
  }

  if (Tok.isNot(tok::r_square))
    // We've already diagnosed a problem here.
    T.skipToEnd();
  else {
    // C++17 does not allow the identifier-list in a structured binding
    // to be empty.
    if (Bindings.empty())
      Diag(Tok.getLocation(), diag::ext_decomp_decl_empty);

    T.consumeClose();
  }

  PA.Commit();

  return D.setDecompositionBindings(T.getOpenLocation(), Bindings,
                                    T.getCloseLocation());
}

/// ParseParenDeclarator - We parsed the declarator D up to a paren.  This is
/// only called before the identifier, so these are most likely just grouping
/// parens for precedence.  If we find that these are actually function
/// parameter parens in an abstract-declarator, we call ParseFunctionDeclarator.
///
///       direct-declarator:
///         '(' declarator ')'
/// [GNU]   '(' attributes declarator ')'
///         direct-declarator '(' parameter-type-list ')'
///         direct-declarator '(' identifier-list[opt] ')'
/// [GNU]   direct-declarator '(' parameter-forward-declarations
///                    parameter-type-list[opt] ')'
///
void Parser::ParseParenDeclarator(Declarator &D) {
  BalancedDelimiterTracker T(*this, tok::l_paren);
  T.consumeOpen();

  assert(!D.isPastIdentifier() && "Should be called before passing identifier");

  // Eat any attributes before we look at whether this is a grouping or function
  // declarator paren.  If this is a grouping paren, the attribute applies to
  // the type being built up, for example:
  //     int (__attribute__(()) *x)(long y)
  // If this ends up not being a grouping paren, the attribute applies to the
  // first argument, for example:
  //     int (__attribute__(()) int x)
  // In either case, we need to eat any attributes to be able to determine what
  // sort of paren this is.
  //
  ParsedAttributes attrs(AttrFactory);
  bool RequiresArg = false;
  if (Tok.is(tok::kw___attribute)) {
    ParseGNUAttributes(attrs);

    // We require that the argument list (if this is a non-grouping paren) be
    // present even if the attribute list was empty.
    RequiresArg = true;
  }

  // Eat any Microsoft extensions.
  ParseMicrosoftTypeAttributes(attrs);

  // Eat any Borland extensions.
  if  (Tok.is(tok::kw___pascal))
    ParseBorlandTypeAttributes(attrs);

  // If we haven't past the identifier yet (or where the identifier would be
  // stored, if this is an abstract declarator), then this is probably just
  // grouping parens. However, if this could be an abstract-declarator, then
  // this could also be the start of function arguments (consider 'void()').
  bool isGrouping;

  if (!D.mayOmitIdentifier()) {
    // If this can't be an abstract-declarator, this *must* be a grouping
    // paren, because we haven't seen the identifier yet.
    isGrouping = true;
  } else if (Tok.is(tok::r_paren) || // 'int()' is a function.
             (getLangOpts().CPlusPlus && Tok.is(tok::ellipsis) &&
              NextToken().is(tok::r_paren)) || // C++ int(...)
             isDeclarationSpecifier(
                 ImplicitTypenameContext::No) || // 'int(int)' is a function.
             isCXX11AttributeSpecifier()) { // 'int([[]]int)' is a function.
    // This handles C99 6.7.5.3p11: in "typedef int X; void foo(X)", X is
    // considered to be a type, not a K&R identifier-list.
    isGrouping = false;
  } else {
    // Otherwise, this is a grouping paren, e.g. 'int (*X)' or 'int(X)'.
    isGrouping = true;
  }

  // If this is a grouping paren, handle:
  // direct-declarator: '(' declarator ')'
  // direct-declarator: '(' attributes declarator ')'
  if (isGrouping) {
    SourceLocation EllipsisLoc = D.getEllipsisLoc();
    D.setEllipsisLoc(SourceLocation());

    bool hadGroupingParens = D.hasGroupingParens();
    D.setGroupingParens(true);
    ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);
    // Match the ')'.
    T.consumeClose();
    D.AddTypeInfo(
        DeclaratorChunk::getParen(T.getOpenLocation(), T.getCloseLocation()),
        std::move(attrs), T.getCloseLocation());

    D.setGroupingParens(hadGroupingParens);

    // An ellipsis cannot be placed outside parentheses.
    if (EllipsisLoc.isValid())
      DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, D);

    return;
  }

  // Okay, if this wasn't a grouping paren, it must be the start of a function
  // argument list.  Recognize that this declarator will never have an
  // identifier (and remember where it would have been), then call into
  // ParseFunctionDeclarator to handle of argument list.
  D.SetIdentifier(nullptr, Tok.getLocation());

  // Enter function-declaration scope, limiting any declarators to the
  // function prototype scope, including parameter declarators.
  ParseScope PrototypeScope(this,
                            Scope::FunctionPrototypeScope | Scope::DeclScope |
                            (D.isFunctionDeclaratorAFunctionDeclaration()
                               ? Scope::FunctionDeclarationScope : 0));
  ParseFunctionDeclarator(D, attrs, T, false, RequiresArg);
  PrototypeScope.Exit();
}

void Parser::InitCXXThisScopeForDeclaratorIfRelevant(
    const Declarator &D, const DeclSpec &DS,
    std::optional<Sema::CXXThisScopeRAII> &ThisScope) {
  // C++11 [expr.prim.general]p3:
  //   If a declaration declares a member function or member function
  //   template of a class X, the expression this is a prvalue of type
  //   "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
  //   and the end of the function-definition, member-declarator, or
  //   declarator.
  // FIXME: currently, "static" case isn't handled correctly.
  bool IsCXX11MemberFunction =
      getLangOpts().CPlusPlus11 &&
      D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_typedef &&
      (D.getContext() == DeclaratorContext::Member
           ? !D.getDeclSpec().isFriendSpecified()
           : D.getContext() == DeclaratorContext::File &&
                 D.getCXXScopeSpec().isValid() &&
                 Actions.CurContext->isRecord());
  if (!IsCXX11MemberFunction)
    return;

  Qualifiers Q = Qualifiers::fromCVRUMask(DS.getTypeQualifiers());
  if (D.getDeclSpec().hasConstexprSpecifier() && !getLangOpts().CPlusPlus14)
    Q.addConst();
  // FIXME: Collect C++ address spaces.
  // If there are multiple different address spaces, the source is invalid.
  // Carry on using the first addr space for the qualifiers of 'this'.
  // The diagnostic will be given later while creating the function
  // prototype for the method.
  if (getLangOpts().OpenCLCPlusPlus) {
    for (ParsedAttr &attr : DS.getAttributes()) {
      LangAS ASIdx = attr.asOpenCLLangAS();
      if (ASIdx != LangAS::Default) {
        Q.addAddressSpace(ASIdx);
        break;
      }
    }
  }
  ThisScope.emplace(Actions, dyn_cast<CXXRecordDecl>(Actions.CurContext), Q,
                    IsCXX11MemberFunction);
}

/// ParseFunctionDeclarator - We are after the identifier and have parsed the
/// declarator D up to a paren, which indicates that we are parsing function
/// arguments.
///
/// If FirstArgAttrs is non-null, then the caller parsed those attributes
/// immediately after the open paren - they will be applied to the DeclSpec
/// of the first parameter.
///
/// If RequiresArg is true, then the first argument of the function is required
/// to be present and required to not be an identifier list.
///
/// For C++, after the parameter-list, it also parses the cv-qualifier-seq[opt],
/// (C++11) ref-qualifier[opt], exception-specification[opt],
/// (C++11) attribute-specifier-seq[opt], (C++11) trailing-return-type[opt] and
/// (C++2a) the trailing requires-clause.
///
/// [C++11] exception-specification:
///           dynamic-exception-specification
///           noexcept-specification
///
void Parser::ParseFunctionDeclarator(Declarator &D,
                                     ParsedAttributes &FirstArgAttrs,
                                     BalancedDelimiterTracker &Tracker,
                                     bool IsAmbiguous,
                                     bool RequiresArg) {
  assert(getCurScope()->isFunctionPrototypeScope() &&
         "Should call from a Function scope");
  // lparen is already consumed!
  assert(D.isPastIdentifier() && "Should not call before identifier!");

  // This should be true when the function has typed arguments.
  // Otherwise, it is treated as a K&R-style function.
  bool HasProto = false;
  // Build up an array of information about the parsed arguments.
  SmallVector<DeclaratorChunk::ParamInfo, 16> ParamInfo;
  // Remember where we see an ellipsis, if any.
  SourceLocation EllipsisLoc;

  DeclSpec DS(AttrFactory);
  bool RefQualifierIsLValueRef = true;
  SourceLocation RefQualifierLoc;
  ExceptionSpecificationType ESpecType = EST_None;
  SourceRange ESpecRange;
  SmallVector<ParsedType, 2> DynamicExceptions;
  SmallVector<SourceRange, 2> DynamicExceptionRanges;
  ExprResult NoexceptExpr;
  CachedTokens *ExceptionSpecTokens = nullptr;
  ParsedAttributes FnAttrs(AttrFactory);
  TypeResult TrailingReturnType;
  SourceLocation TrailingReturnTypeLoc;

  /* LocalEndLoc is the end location for the local FunctionTypeLoc.
     EndLoc is the end location for the function declarator.
     They differ for trailing return types. */
  SourceLocation StartLoc, LocalEndLoc, EndLoc;
  SourceLocation LParenLoc, RParenLoc;
  LParenLoc = Tracker.getOpenLocation();
  StartLoc = LParenLoc;

  if (isFunctionDeclaratorIdentifierList()) {
    if (RequiresArg)
      Diag(Tok, diag::err_argument_required_after_attribute);

    ParseFunctionDeclaratorIdentifierList(D, ParamInfo);

    Tracker.consumeClose();
    RParenLoc = Tracker.getCloseLocation();
    LocalEndLoc = RParenLoc;
    EndLoc = RParenLoc;

    // If there are attributes following the identifier list, parse them and
    // prohibit them.
    MaybeParseCXX11Attributes(FnAttrs);
    ProhibitAttributes(FnAttrs);
  } else {
    if (Tok.isNot(tok::r_paren))
      ParseParameterDeclarationClause(D, FirstArgAttrs, ParamInfo, EllipsisLoc);
    else if (RequiresArg)
      Diag(Tok, diag::err_argument_required_after_attribute);

    // OpenCL disallows functions without a prototype, but it doesn't enforce
    // strict prototypes as in C23 because it allows a function definition to
    // have an identifier list. See OpenCL 3.0 6.11/g for more details.
    HasProto = ParamInfo.size() || getLangOpts().requiresStrictPrototypes() ||
               getLangOpts().OpenCL;

    // If we have the closing ')', eat it.
    Tracker.consumeClose();
    RParenLoc = Tracker.getCloseLocation();
    LocalEndLoc = RParenLoc;
    EndLoc = RParenLoc;

    if (getLangOpts().CPlusPlus) {
      // FIXME: Accept these components in any order, and produce fixits to
      // correct the order if the user gets it wrong. Ideally we should deal
      // with the pure-specifier in the same way.

      // Parse cv-qualifier-seq[opt].
      ParseTypeQualifierListOpt(
          DS, AR_NoAttributesParsed,
          /*AtomicAllowed*/ false,
          /*IdentifierRequired=*/false, llvm::function_ref<void()>([&]() {
            Actions.CodeCompletion().CodeCompleteFunctionQualifiers(DS, D);
          }));
      if (!DS.getSourceRange().getEnd().isInvalid()) {
        EndLoc = DS.getSourceRange().getEnd();
      }

      // Parse ref-qualifier[opt].
      if (ParseRefQualifier(RefQualifierIsLValueRef, RefQualifierLoc))
        EndLoc = RefQualifierLoc;

      std::optional<Sema::CXXThisScopeRAII> ThisScope;
      InitCXXThisScopeForDeclaratorIfRelevant(D, DS, ThisScope);

      // C++ [class.mem.general]p8:
      //   A complete-class context of a class (template) is a
      //     - function body,
      //     - default argument,
      //     - default template argument,
      //     - noexcept-specifier, or
      //     - default member initializer
      //   within the member-specification of the class or class template.
      //
      // Parse exception-specification[opt]. If we are in the
      // member-specification of a class or class template, this is a
      // complete-class context and parsing of the noexcept-specifier should be
      // delayed (even if this is a friend declaration).
      bool Delayed = D.getContext() == DeclaratorContext::Member &&
                     D.isFunctionDeclaratorAFunctionDeclaration();
      if (Delayed && Actions.isLibstdcxxEagerExceptionSpecHack(D) &&
          GetLookAheadToken(0).is(tok::kw_noexcept) &&
          GetLookAheadToken(1).is(tok::l_paren) &&
          GetLookAheadToken(2).is(tok::kw_noexcept) &&
          GetLookAheadToken(3).is(tok::l_paren) &&
          GetLookAheadToken(4).is(tok::identifier) &&
          GetLookAheadToken(4).getIdentifierInfo()->isStr("swap")) {
        // HACK: We've got an exception-specification
        //   noexcept(noexcept(swap(...)))
        // or
        //   noexcept(noexcept(swap(...)) && noexcept(swap(...)))
        // on a 'swap' member function. This is a libstdc++ bug; the lookup
        // for 'swap' will only find the function we're currently declaring,
        // whereas it expects to find a non-member swap through ADL. Turn off
        // delayed parsing to give it a chance to find what it expects.
        Delayed = false;
      }
      ESpecType = tryParseExceptionSpecification(Delayed,
                                                 ESpecRange,
                                                 DynamicExceptions,
                                                 DynamicExceptionRanges,
                                                 NoexceptExpr,
                                                 ExceptionSpecTokens);
      if (ESpecType != EST_None)
        EndLoc = ESpecRange.getEnd();

      // Parse attribute-specifier-seq[opt]. Per DR 979 and DR 1297, this goes
      // after the exception-specification.
      MaybeParseCXX11Attributes(FnAttrs);

      // Parse trailing-return-type[opt].
      LocalEndLoc = EndLoc;
      if (getLangOpts().CPlusPlus11 && Tok.is(tok::arrow)) {
        Diag(Tok, diag::warn_cxx98_compat_trailing_return_type);
        if (D.getDeclSpec().getTypeSpecType() == TST_auto)
          StartLoc = D.getDeclSpec().getTypeSpecTypeLoc();
        LocalEndLoc = Tok.getLocation();
        SourceRange Range;
        TrailingReturnType =
            ParseTrailingReturnType(Range, D.mayBeFollowedByCXXDirectInit());
        TrailingReturnTypeLoc = Range.getBegin();
        EndLoc = Range.getEnd();
      }
    } else {
      MaybeParseCXX11Attributes(FnAttrs);
    }
  }

  // Collect non-parameter declarations from the prototype if this is a function
  // declaration. They will be moved into the scope of the function. Only do
  // this in C and not C++, where the decls will continue to live in the
  // surrounding context.
  SmallVector<NamedDecl *, 0> DeclsInPrototype;
  if (getCurScope()->isFunctionDeclarationScope() && !getLangOpts().CPlusPlus) {
    for (Decl *D : getCurScope()->decls()) {
      NamedDecl *ND = dyn_cast<NamedDecl>(D);
      if (!ND || isa<ParmVarDecl>(ND))
        continue;
      DeclsInPrototype.push_back(ND);
    }
    // Sort DeclsInPrototype based on raw encoding of the source location.
    // Scope::decls() is iterating over a SmallPtrSet so sort the Decls before
    // moving to DeclContext. This provides a stable ordering for traversing
    // Decls in DeclContext, which is important for tasks like ASTWriter for
    // deterministic output.
    llvm::sort(DeclsInPrototype, [](Decl *D1, Decl *D2) {
      return D1->getLocation().getRawEncoding() <
             D2->getLocation().getRawEncoding();
    });
  }

  // Remember that we parsed a function type, and remember the attributes.
  D.AddTypeInfo(DeclaratorChunk::getFunction(
                    HasProto, IsAmbiguous, LParenLoc, ParamInfo.data(),
                    ParamInfo.size(), EllipsisLoc, RParenLoc,
                    RefQualifierIsLValueRef, RefQualifierLoc,
                    /*MutableLoc=*/SourceLocation(),
                    ESpecType, ESpecRange, DynamicExceptions.data(),
                    DynamicExceptionRanges.data(), DynamicExceptions.size(),
                    NoexceptExpr.isUsable() ? NoexceptExpr.get() : nullptr,
                    ExceptionSpecTokens, DeclsInPrototype, StartLoc,
                    LocalEndLoc, D, TrailingReturnType, TrailingReturnTypeLoc,
                    &DS),
                std::move(FnAttrs), EndLoc);
}

/// ParseRefQualifier - Parses a member function ref-qualifier. Returns
/// true if a ref-qualifier is found.
bool Parser::ParseRefQualifier(bool &RefQualifierIsLValueRef,
                               SourceLocation &RefQualifierLoc) {
  if (Tok.isOneOf(tok::amp, tok::ampamp)) {
    Diag(Tok, getLangOpts().CPlusPlus11 ?
         diag::warn_cxx98_compat_ref_qualifier :
         diag::ext_ref_qualifier);

    RefQualifierIsLValueRef = Tok.is(tok::amp);
    RefQualifierLoc = ConsumeToken();
    return true;
  }
  return false;
}

/// isFunctionDeclaratorIdentifierList - This parameter list may have an
/// identifier list form for a K&R-style function:  void foo(a,b,c)
///
/// Note that identifier-lists are only allowed for normal declarators, not for
/// abstract-declarators.
bool Parser::isFunctionDeclaratorIdentifierList() {
  return !getLangOpts().requiresStrictPrototypes()
         && Tok.is(tok::identifier)
         && !TryAltiVecVectorToken()
         // K&R identifier lists can't have typedefs as identifiers, per C99
         // 6.7.5.3p11.
         && (TryAnnotateTypeOrScopeToken() || !Tok.is(tok::annot_typename))
         // Identifier lists follow a really simple grammar: the identifiers can
         // be followed *only* by a ", identifier" or ")".  However, K&R
         // identifier lists are really rare in the brave new modern world, and
         // it is very common for someone to typo a type in a non-K&R style
         // list.  If we are presented with something like: "void foo(intptr x,
         // float y)", we don't want to start parsing the function declarator as
         // though it is a K&R style declarator just because intptr is an
         // invalid type.
         //
         // To handle this, we check to see if the token after the first
         // identifier is a "," or ")".  Only then do we parse it as an
         // identifier list.
         && (!Tok.is(tok::eof) &&
             (NextToken().is(tok::comma) || NextToken().is(tok::r_paren)));
}

/// ParseFunctionDeclaratorIdentifierList - While parsing a function declarator
/// we found a K&R-style identifier list instead of a typed parameter list.
///
/// After returning, ParamInfo will hold the parsed parameters.
///
///       identifier-list: [C99 6.7.5]
///         identifier
///         identifier-list ',' identifier
///
void Parser::ParseFunctionDeclaratorIdentifierList(
       Declarator &D,
       SmallVectorImpl<DeclaratorChunk::ParamInfo> &ParamInfo) {
  // We should never reach this point in C23 or C++.
  assert(!getLangOpts().requiresStrictPrototypes() &&
         "Cannot parse an identifier list in C23 or C++");

  // If there was no identifier specified for the declarator, either we are in
  // an abstract-declarator, or we are in a parameter declarator which was found
  // to be abstract.  In abstract-declarators, identifier lists are not valid:
  // diagnose this.
  if (!D.getIdentifier())
    Diag(Tok, diag::ext_ident_list_in_param);

  // Maintain an efficient lookup of params we have seen so far.
  llvm::SmallSet<const IdentifierInfo*, 16> ParamsSoFar;

  do {
    // If this isn't an identifier, report the error and skip until ')'.
    if (Tok.isNot(tok::identifier)) {
      Diag(Tok, diag::err_expected) << tok::identifier;
      SkipUntil(tok::r_paren, StopAtSemi | StopBeforeMatch);
      // Forget we parsed anything.
      ParamInfo.clear();
      return;
    }

    IdentifierInfo *ParmII = Tok.getIdentifierInfo();

    // Reject 'typedef int y; int test(x, y)', but continue parsing.
    if (Actions.getTypeName(*ParmII, Tok.getLocation(), getCurScope()))
      Diag(Tok, diag::err_unexpected_typedef_ident) << ParmII;

    // Verify that the argument identifier has not already been mentioned.
    if (!ParamsSoFar.insert(ParmII).second) {
      Diag(Tok, diag::err_param_redefinition) << ParmII;
    } else {
      // Remember this identifier in ParamInfo.
      ParamInfo.push_back(DeclaratorChunk::ParamInfo(ParmII,
                                                     Tok.getLocation(),
                                                     nullptr));
    }

    // Eat the identifier.
    ConsumeToken();
    // The list continues if we see a comma.
  } while (TryConsumeToken(tok::comma));
}

/// ParseParameterDeclarationClause - Parse a (possibly empty) parameter-list
/// after the opening parenthesis. This function will not parse a K&R-style
/// identifier list.
///
/// DeclContext is the context of the declarator being parsed.  If FirstArgAttrs
/// is non-null, then the caller parsed those attributes immediately after the
/// open paren - they will be applied to the DeclSpec of the first parameter.
///
/// After returning, ParamInfo will hold the parsed parameters. EllipsisLoc will
/// be the location of the ellipsis, if any was parsed.
///
///       parameter-type-list: [C99 6.7.5]
///         parameter-list
///         parameter-list ',' '...'
/// [C++]   parameter-list '...'
///
///       parameter-list: [C99 6.7.5]
///         parameter-declaration
///         parameter-list ',' parameter-declaration
///
///       parameter-declaration: [C99 6.7.5]
///         declaration-specifiers declarator
/// [C++]   declaration-specifiers declarator '=' assignment-expression
/// [C++11]                                       initializer-clause
/// [GNU]   declaration-specifiers declarator attributes
///         declaration-specifiers abstract-declarator[opt]
/// [C++]   declaration-specifiers abstract-declarator[opt]
///           '=' assignment-expression
/// [GNU]   declaration-specifiers abstract-declarator[opt] attributes
/// [C++11] attribute-specifier-seq parameter-declaration
/// [C++2b] attribute-specifier-seq 'this' parameter-declaration
///
void Parser::ParseParameterDeclarationClause(
    DeclaratorContext DeclaratorCtx, ParsedAttributes &FirstArgAttrs,
    SmallVectorImpl<DeclaratorChunk::ParamInfo> &ParamInfo,
    SourceLocation &EllipsisLoc, bool IsACXXFunctionDeclaration) {

  // Avoid exceeding the maximum function scope depth.
  // See https://bugs.llvm.org/show_bug.cgi?id=19607
  // Note Sema::ActOnParamDeclarator calls ParmVarDecl::setScopeInfo with
  // getFunctionPrototypeDepth() - 1.
  if (getCurScope()->getFunctionPrototypeDepth() - 1 >
      ParmVarDecl::getMaxFunctionScopeDepth()) {
    Diag(Tok.getLocation(), diag::err_function_scope_depth_exceeded)
        << ParmVarDecl::getMaxFunctionScopeDepth();
    cutOffParsing();
    return;
  }

  // C++2a [temp.res]p5
  // A qualified-id is assumed to name a type if
  //   - [...]
  //   - it is a decl-specifier of the decl-specifier-seq of a
  //     - [...]
  //     - parameter-declaration in a member-declaration [...]
  //     - parameter-declaration in a declarator of a function or function
  //       template declaration whose declarator-id is qualified [...]
  //     - parameter-declaration in a lambda-declarator [...]
  auto AllowImplicitTypename = ImplicitTypenameContext::No;
  if (DeclaratorCtx == DeclaratorContext::Member ||
      DeclaratorCtx == DeclaratorContext::LambdaExpr ||
      DeclaratorCtx == DeclaratorContext::RequiresExpr ||
      IsACXXFunctionDeclaration) {
    AllowImplicitTypename = ImplicitTypenameContext::Yes;
  }

  do {
    // FIXME: Issue a diagnostic if we parsed an attribute-specifier-seq
    // before deciding this was a parameter-declaration-clause.
    if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
      break;

    // Parse the declaration-specifiers.
    // Just use the ParsingDeclaration "scope" of the declarator.
    DeclSpec DS(AttrFactory);

    ParsedAttributes ArgDeclAttrs(AttrFactory);
    ParsedAttributes ArgDeclSpecAttrs(AttrFactory);

    if (FirstArgAttrs.Range.isValid()) {
      // If the caller parsed attributes for the first argument, add them now.
      // Take them so that we only apply the attributes to the first parameter.
      // We have already started parsing the decl-specifier sequence, so don't
      // parse any parameter-declaration pieces that precede it.
      ArgDeclSpecAttrs.takeAllFrom(FirstArgAttrs);
    } else {
      // Parse any C++11 attributes.
      MaybeParseCXX11Attributes(ArgDeclAttrs);

      // Skip any Microsoft attributes before a param.
      MaybeParseMicrosoftAttributes(ArgDeclSpecAttrs);
    }

    SourceLocation DSStart = Tok.getLocation();

    // Parse a C++23 Explicit Object Parameter
    // We do that in all language modes to produce a better diagnostic.
    SourceLocation ThisLoc;
    if (getLangOpts().CPlusPlus && Tok.is(tok::kw_this)) {
      ThisLoc = ConsumeToken();
      // C++23 [dcl.fct]p6:
      //   An explicit-object-parameter-declaration is a parameter-declaration
      //   with a this specifier. An explicit-object-parameter-declaration
      //   shall appear only as the first parameter-declaration of a
      //   parameter-declaration-list of either:
      //   - a member-declarator that declares a member function, or
      //   - a lambda-declarator.
      //
      // The parameter-declaration-list of a requires-expression is not such
      // a context.
      if (DeclaratorCtx == DeclaratorContext::RequiresExpr)
        Diag(ThisLoc, diag::err_requires_expr_explicit_object_parameter);
    }

    ParsedTemplateInfo TemplateInfo;
    ParseDeclarationSpecifiers(DS, TemplateInfo, AS_none,
                               DeclSpecContext::DSC_normal,
                               /*LateAttrs=*/nullptr, AllowImplicitTypename);

    DS.takeAttributesFrom(ArgDeclSpecAttrs);

    // Parse the declarator.  This is "PrototypeContext" or
    // "LambdaExprParameterContext", because we must accept either
    // 'declarator' or 'abstract-declarator' here.
    Declarator ParmDeclarator(DS, ArgDeclAttrs,
                              DeclaratorCtx == DeclaratorContext::RequiresExpr
                                  ? DeclaratorContext::RequiresExpr
                              : DeclaratorCtx == DeclaratorContext::LambdaExpr
                                  ? DeclaratorContext::LambdaExprParameter
                                  : DeclaratorContext::Prototype);
    ParseDeclarator(ParmDeclarator);

    if (ThisLoc.isValid())
      ParmDeclarator.SetRangeBegin(ThisLoc);

    // Parse GNU attributes, if present.
    MaybeParseGNUAttributes(ParmDeclarator);
    if (getLangOpts().HLSL)
      MaybeParseHLSLAnnotations(DS.getAttributes());

    if (Tok.is(tok::kw_requires)) {
      // User tried to define a requires clause in a parameter declaration,
      // which is surely not a function declaration.
      // void f(int (*g)(int, int) requires true);
      Diag(Tok,
           diag::err_requires_clause_on_declarator_not_declaring_a_function);
      ConsumeToken();
      Actions.CorrectDelayedTyposInExpr(
         ParseConstraintLogicalOrExpression(/*IsTrailingRequiresClause=*/true));
    }

    // Remember this parsed parameter in ParamInfo.
    const IdentifierInfo *ParmII = ParmDeclarator.getIdentifier();

    // DefArgToks is used when the parsing of default arguments needs
    // to be delayed.
    std::unique_ptr<CachedTokens> DefArgToks;

    // If no parameter was specified, verify that *something* was specified,
    // otherwise we have a missing type and identifier.
    if (DS.isEmpty() && ParmDeclarator.getIdentifier() == nullptr &&
        ParmDeclarator.getNumTypeObjects() == 0) {
      // Completely missing, emit error.
      Diag(DSStart, diag::err_missing_param);
    } else {
      // Otherwise, we have something.  Add it and let semantic analysis try
      // to grok it and add the result to the ParamInfo we are building.

      // Last chance to recover from a misplaced ellipsis in an attempted
      // parameter pack declaration.
      if (Tok.is(tok::ellipsis) &&
          (NextToken().isNot(tok::r_paren) ||
           (!ParmDeclarator.getEllipsisLoc().isValid() &&
            !Actions.isUnexpandedParameterPackPermitted())) &&
          Actions.containsUnexpandedParameterPacks(ParmDeclarator))
        DiagnoseMisplacedEllipsisInDeclarator(ConsumeToken(), ParmDeclarator);

      // Now we are at the point where declarator parsing is finished.
      //
      // Try to catch keywords in place of the identifier in a declarator, and
      // in particular the common case where:
      //   1 identifier comes at the end of the declarator
      //   2 if the identifier is dropped, the declarator is valid but anonymous
      //     (no identifier)
      //   3 declarator parsing succeeds, and then we have a trailing keyword,
      //     which is never valid in a param list (e.g. missing a ',')
      // And we can't handle this in ParseDeclarator because in general keywords
      // may be allowed to follow the declarator. (And in some cases there'd be
      // better recovery like inserting punctuation). ParseDeclarator is just
      // treating this as an anonymous parameter, and fortunately at this point
      // we've already almost done that.
      //
      // We care about case 1) where the declarator type should be known, and
      // the identifier should be null.
      if (!ParmDeclarator.isInvalidType() && !ParmDeclarator.hasName() &&
          Tok.isNot(tok::raw_identifier) && !Tok.isAnnotation() &&
          Tok.getIdentifierInfo() &&
          Tok.getIdentifierInfo()->isKeyword(getLangOpts())) {
        Diag(Tok, diag::err_keyword_as_parameter) << PP.getSpelling(Tok);
        // Consume the keyword.
        ConsumeToken();
      }
      // Inform the actions module about the parameter declarator, so it gets
      // added to the current scope.
      Decl *Param =
          Actions.ActOnParamDeclarator(getCurScope(), ParmDeclarator, ThisLoc);
      // Parse the default argument, if any. We parse the default
      // arguments in all dialects; the semantic analysis in
      // ActOnParamDefaultArgument will reject the default argument in
      // C.
      if (Tok.is(tok::equal)) {
        SourceLocation EqualLoc = Tok.getLocation();

        // Parse the default argument
        if (DeclaratorCtx == DeclaratorContext::Member) {
          // If we're inside a class definition, cache the tokens
          // corresponding to the default argument. We'll actually parse
          // them when we see the end of the class definition.
          DefArgToks.reset(new CachedTokens);

          SourceLocation ArgStartLoc = NextToken().getLocation();
          ConsumeAndStoreInitializer(*DefArgToks, CIK_DefaultArgument);
          Actions.ActOnParamUnparsedDefaultArgument(Param, EqualLoc,
                                                    ArgStartLoc);
        } else {
          // Consume the '='.
          ConsumeToken();

          // The argument isn't actually potentially evaluated unless it is
          // used.
          EnterExpressionEvaluationContext Eval(
              Actions,
              Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed,
              Param);

          ExprResult DefArgResult;
          if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
            Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
            DefArgResult = ParseBraceInitializer();
          } else {
            if (Tok.is(tok::l_paren) && NextToken().is(tok::l_brace)) {
              Diag(Tok, diag::err_stmt_expr_in_default_arg) << 0;
              Actions.ActOnParamDefaultArgumentError(Param, EqualLoc,
                                                     /*DefaultArg=*/nullptr);
              // Skip the statement expression and continue parsing
              SkipUntil(tok::comma, StopBeforeMatch);
              continue;
            }
            DefArgResult = ParseAssignmentExpression();
          }
          DefArgResult = Actions.CorrectDelayedTyposInExpr(DefArgResult);
          if (DefArgResult.isInvalid()) {
            Actions.ActOnParamDefaultArgumentError(Param, EqualLoc,
                                                   /*DefaultArg=*/nullptr);
            SkipUntil(tok::comma, tok::r_paren, StopAtSemi | StopBeforeMatch);
          } else {
            // Inform the actions module about the default argument
            Actions.ActOnParamDefaultArgument(Param, EqualLoc,
                                              DefArgResult.get());
          }
        }
      }

      ParamInfo.push_back(DeclaratorChunk::ParamInfo(ParmII,
                                          ParmDeclarator.getIdentifierLoc(),
                                          Param, std::move(DefArgToks)));
    }

    if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) {
      if (!getLangOpts().CPlusPlus) {
        // We have ellipsis without a preceding ',', which is ill-formed
        // in C. Complain and provide the fix.
        Diag(EllipsisLoc, diag::err_missing_comma_before_ellipsis)
            << FixItHint::CreateInsertion(EllipsisLoc, ", ");
      } else if (ParmDeclarator.getEllipsisLoc().isValid() ||
                 Actions.containsUnexpandedParameterPacks(ParmDeclarator)) {
        // It looks like this was supposed to be a parameter pack. Warn and
        // point out where the ellipsis should have gone.
        SourceLocation ParmEllipsis = ParmDeclarator.getEllipsisLoc();
        Diag(EllipsisLoc, diag::warn_misplaced_ellipsis_vararg)
          << ParmEllipsis.isValid() << ParmEllipsis;
        if (ParmEllipsis.isValid()) {
          Diag(ParmEllipsis,
               diag::note_misplaced_ellipsis_vararg_existing_ellipsis);
        } else {
          Diag(ParmDeclarator.getIdentifierLoc(),
               diag::note_misplaced_ellipsis_vararg_add_ellipsis)
            << FixItHint::CreateInsertion(ParmDeclarator.getIdentifierLoc(),
                                          "...")
            << !ParmDeclarator.hasName();
        }
        Diag(EllipsisLoc, diag::note_misplaced_ellipsis_vararg_add_comma)
          << FixItHint::CreateInsertion(EllipsisLoc, ", ");
      }

      // We can't have any more parameters after an ellipsis.
      break;
    }

    // If the next token is a comma, consume it and keep reading arguments.
  } while (TryConsumeToken(tok::comma));
}

/// [C90]   direct-declarator '[' constant-expression[opt] ']'
/// [C99]   direct-declarator '[' type-qual-list[opt] assignment-expr[opt] ']'
/// [C99]   direct-declarator '[' 'static' type-qual-list[opt] assign-expr ']'
/// [C99]   direct-declarator '[' type-qual-list 'static' assignment-expr ']'
/// [C99]   direct-declarator '[' type-qual-list[opt] '*' ']'
/// [C++11] direct-declarator '[' constant-expression[opt] ']'
///                           attribute-specifier-seq[opt]
void Parser::ParseBracketDeclarator(Declarator &D) {
  if (CheckProhibitedCXX11Attribute())
    return;

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

  // C array syntax has many features, but by-far the most common is [] and [4].
  // This code does a fast path to handle some of the most obvious cases.
  if (Tok.getKind() == tok::r_square) {
    T.consumeClose();
    ParsedAttributes attrs(AttrFactory);
    MaybeParseCXX11Attributes(attrs);

    // Remember that we parsed the empty array type.
    D.AddTypeInfo(DeclaratorChunk::getArray(0, false, false, nullptr,
                                            T.getOpenLocation(),
                                            T.getCloseLocation()),
                  std::move(attrs), T.getCloseLocation());
    return;
  } else if (Tok.getKind() == tok::numeric_constant &&
             GetLookAheadToken(1).is(tok::r_square)) {
    // [4] is very common.  Parse the numeric constant expression.
    ExprResult ExprRes(Actions.ActOnNumericConstant(Tok, getCurScope()));
    ConsumeToken();

    T.consumeClose();
    ParsedAttributes attrs(AttrFactory);
    MaybeParseCXX11Attributes(attrs);

    // Remember that we parsed a array type, and remember its features.
    D.AddTypeInfo(DeclaratorChunk::getArray(0, false, false, ExprRes.get(),
                                            T.getOpenLocation(),
                                            T.getCloseLocation()),
                  std::move(attrs), T.getCloseLocation());
    return;
  } else if (Tok.getKind() == tok::code_completion) {
    cutOffParsing();
    Actions.CodeCompletion().CodeCompleteBracketDeclarator(getCurScope());
    return;
  }

  // If valid, this location is the position where we read the 'static' keyword.
  SourceLocation StaticLoc;
  TryConsumeToken(tok::kw_static, StaticLoc);

  // If there is a type-qualifier-list, read it now.
  // Type qualifiers in an array subscript are a C99 feature.
  DeclSpec DS(AttrFactory);
  ParseTypeQualifierListOpt(DS, AR_CXX11AttributesParsed);

  // If we haven't already read 'static', check to see if there is one after the
  // type-qualifier-list.
  if (!StaticLoc.isValid())
    TryConsumeToken(tok::kw_static, StaticLoc);

  // Handle "direct-declarator [ type-qual-list[opt] * ]".
  bool isStar = false;
  ExprResult NumElements;

  // Handle the case where we have '[*]' as the array size.  However, a leading
  // star could be the start of an expression, for example 'X[*p + 4]'.  Verify
  // the token after the star is a ']'.  Since stars in arrays are
  // infrequent, use of lookahead is not costly here.
  if (Tok.is(tok::star) && GetLookAheadToken(1).is(tok::r_square)) {
    ConsumeToken();  // Eat the '*'.

    if (StaticLoc.isValid()) {
      Diag(StaticLoc, diag::err_unspecified_vla_size_with_static);
      StaticLoc = SourceLocation();  // Drop the static.
    }
    isStar = true;
  } else if (Tok.isNot(tok::r_square)) {
    // Note, in C89, this production uses the constant-expr production instead
    // of assignment-expr.  The only difference is that assignment-expr allows
    // things like '=' and '*='.  Sema rejects these in C89 mode because they
    // are not i-c-e's, so we don't need to distinguish between the two here.

    // Parse the constant-expression or assignment-expression now (depending
    // on dialect).
    if (getLangOpts().CPlusPlus) {
      NumElements = ParseArrayBoundExpression();
    } else {
      EnterExpressionEvaluationContext Unevaluated(
          Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
      NumElements =
          Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression());
    }
  } else {
    if (StaticLoc.isValid()) {
      Diag(StaticLoc, diag::err_unspecified_size_with_static);
      StaticLoc = SourceLocation();  // Drop the static.
    }
  }

  // If there was an error parsing the assignment-expression, recover.
  if (NumElements.isInvalid()) {
    D.setInvalidType(true);
    // If the expression was invalid, skip it.
    SkipUntil(tok::r_square, StopAtSemi);
    return;
  }

  T.consumeClose();

  MaybeParseCXX11Attributes(DS.getAttributes());

  // Remember that we parsed a array type, and remember its features.
  D.AddTypeInfo(
      DeclaratorChunk::getArray(DS.getTypeQualifiers(), StaticLoc.isValid(),
                                isStar, NumElements.get(), T.getOpenLocation(),
                                T.getCloseLocation()),
      std::move(DS.getAttributes()), T.getCloseLocation());
}

/// Diagnose brackets before an identifier.
void Parser::ParseMisplacedBracketDeclarator(Declarator &D) {
  assert(Tok.is(tok::l_square) && "Missing opening bracket");
  assert(!D.mayOmitIdentifier() && "Declarator cannot omit identifier");

  SourceLocation StartBracketLoc = Tok.getLocation();
  Declarator TempDeclarator(D.getDeclSpec(), ParsedAttributesView::none(),
                            D.getContext());

  while (Tok.is(tok::l_square)) {
    ParseBracketDeclarator(TempDeclarator);
  }

  // Stuff the location of the start of the brackets into the Declarator.
  // The diagnostics from ParseDirectDeclarator will make more sense if
  // they use this location instead.
  if (Tok.is(tok::semi))
    D.getName().EndLocation = StartBracketLoc;

  SourceLocation SuggestParenLoc = Tok.getLocation();

  // Now that the brackets are removed, try parsing the declarator again.
  ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);

  // Something went wrong parsing the brackets, in which case,
  // ParseBracketDeclarator has emitted an error, and we don't need to emit
  // one here.
  if (TempDeclarator.getNumTypeObjects() == 0)
    return;

  // Determine if parens will need to be suggested in the diagnostic.
  bool NeedParens = false;
  if (D.getNumTypeObjects() != 0) {
    switch (D.getTypeObject(D.getNumTypeObjects() - 1).Kind) {
    case DeclaratorChunk::Pointer:
    case DeclaratorChunk::Reference:
    case DeclaratorChunk::BlockPointer:
    case DeclaratorChunk::MemberPointer:
    case DeclaratorChunk::Pipe:
      NeedParens = true;
      break;
    case DeclaratorChunk::Array:
    case DeclaratorChunk::Function:
    case DeclaratorChunk::Paren:
      break;
    }
  }

  if (NeedParens) {
    // Create a DeclaratorChunk for the inserted parens.
    SourceLocation EndLoc = PP.getLocForEndOfToken(D.getEndLoc());
    D.AddTypeInfo(DeclaratorChunk::getParen(SuggestParenLoc, EndLoc),
                  SourceLocation());
  }

  // Adding back the bracket info to the end of the Declarator.
  for (unsigned i = 0, e = TempDeclarator.getNumTypeObjects(); i < e; ++i) {
    const DeclaratorChunk &Chunk = TempDeclarator.getTypeObject(i);
    D.AddTypeInfo(Chunk, TempDeclarator.getAttributePool(), SourceLocation());
  }

  // The missing identifier would have been diagnosed in ParseDirectDeclarator.
  // If parentheses are required, always suggest them.
  if (!D.getIdentifier() && !NeedParens)
    return;

  SourceLocation EndBracketLoc = TempDeclarator.getEndLoc();

  // Generate the move bracket error message.
  SourceRange BracketRange(StartBracketLoc, EndBracketLoc);
  SourceLocation EndLoc = PP.getLocForEndOfToken(D.getEndLoc());

  if (NeedParens) {
    Diag(EndLoc, diag::err_brackets_go_after_unqualified_id)
        << getLangOpts().CPlusPlus
        << FixItHint::CreateInsertion(SuggestParenLoc, "(")
        << FixItHint::CreateInsertion(EndLoc, ")")
        << FixItHint::CreateInsertionFromRange(
               EndLoc, CharSourceRange(BracketRange, true))
        << FixItHint::CreateRemoval(BracketRange);
  } else {
    Diag(EndLoc, diag::err_brackets_go_after_unqualified_id)
        << getLangOpts().CPlusPlus
        << FixItHint::CreateInsertionFromRange(
               EndLoc, CharSourceRange(BracketRange, true))
        << FixItHint::CreateRemoval(BracketRange);
  }
}

/// [GNU]   typeof-specifier:
///           typeof ( expressions )
///           typeof ( type-name )
/// [GNU/C++] typeof unary-expression
/// [C23]   typeof-specifier:
///           typeof '(' typeof-specifier-argument ')'
///           typeof_unqual '(' typeof-specifier-argument ')'
///
///         typeof-specifier-argument:
///           expression
///           type-name
///
void Parser::ParseTypeofSpecifier(DeclSpec &DS) {
  assert(Tok.isOneOf(tok::kw_typeof, tok::kw_typeof_unqual) &&
         "Not a typeof specifier");

  bool IsUnqual = Tok.is(tok::kw_typeof_unqual);
  const IdentifierInfo *II = Tok.getIdentifierInfo();
  if (getLangOpts().C23 && !II->getName().starts_with("__"))
    Diag(Tok.getLocation(), diag::warn_c23_compat_keyword) << Tok.getName();

  Token OpTok = Tok;
  SourceLocation StartLoc = ConsumeToken();
  bool HasParens = Tok.is(tok::l_paren);

  EnterExpressionEvaluationContext Unevaluated(
      Actions, Sema::ExpressionEvaluationContext::Unevaluated,
      Sema::ReuseLambdaContextDecl);

  bool isCastExpr;
  ParsedType CastTy;
  SourceRange CastRange;
  ExprResult Operand = Actions.CorrectDelayedTyposInExpr(
      ParseExprAfterUnaryExprOrTypeTrait(OpTok, isCastExpr, CastTy, CastRange));
  if (HasParens)
    DS.setTypeArgumentRange(CastRange);

  if (CastRange.getEnd().isInvalid())
    // FIXME: Not accurate, the range gets one token more than it should.
    DS.SetRangeEnd(Tok.getLocation());
  else
    DS.SetRangeEnd(CastRange.getEnd());

  if (isCastExpr) {
    if (!CastTy) {
      DS.SetTypeSpecError();
      return;
    }

    const char *PrevSpec = nullptr;
    unsigned DiagID;
    // Check for duplicate type specifiers (e.g. "int typeof(int)").
    if (DS.SetTypeSpecType(IsUnqual ? DeclSpec::TST_typeof_unqualType
                                    : DeclSpec::TST_typeofType,
                           StartLoc, PrevSpec,
                           DiagID, CastTy,
                           Actions.getASTContext().getPrintingPolicy()))
      Diag(StartLoc, DiagID) << PrevSpec;
    return;
  }

  // If we get here, the operand to the typeof was an expression.
  if (Operand.isInvalid()) {
    DS.SetTypeSpecError();
    return;
  }

  // We might need to transform the operand if it is potentially evaluated.
  Operand = Actions.HandleExprEvaluationContextForTypeof(Operand.get());
  if (Operand.isInvalid()) {
    DS.SetTypeSpecError();
    return;
  }

  const char *PrevSpec = nullptr;
  unsigned DiagID;
  // Check for duplicate type specifiers (e.g. "int typeof(int)").
  if (DS.SetTypeSpecType(IsUnqual ? DeclSpec::TST_typeof_unqualExpr
                                  : DeclSpec::TST_typeofExpr,
                         StartLoc, PrevSpec,
                         DiagID, Operand.get(),
                         Actions.getASTContext().getPrintingPolicy()))
    Diag(StartLoc, DiagID) << PrevSpec;
}

/// [C11]   atomic-specifier:
///           _Atomic ( type-name )
///
void Parser::ParseAtomicSpecifier(DeclSpec &DS) {
  assert(Tok.is(tok::kw__Atomic) && NextToken().is(tok::l_paren) &&
         "Not an atomic specifier");

  SourceLocation StartLoc = ConsumeToken();
  BalancedDelimiterTracker T(*this, tok::l_paren);
  if (T.consumeOpen())
    return;

  TypeResult Result = ParseTypeName();
  if (Result.isInvalid()) {
    SkipUntil(tok::r_paren, StopAtSemi);
    return;
  }

  // Match the ')'
  T.consumeClose();

  if (T.getCloseLocation().isInvalid())
    return;

  DS.setTypeArgumentRange(T.getRange());
  DS.SetRangeEnd(T.getCloseLocation());

  const char *PrevSpec = nullptr;
  unsigned DiagID;
  if (DS.SetTypeSpecType(DeclSpec::TST_atomic, StartLoc, PrevSpec,
                         DiagID, Result.get(),
                         Actions.getASTContext().getPrintingPolicy()))
    Diag(StartLoc, DiagID) << PrevSpec;
}

/// TryAltiVecVectorTokenOutOfLine - Out of line body that should only be called
/// from TryAltiVecVectorToken.
bool Parser::TryAltiVecVectorTokenOutOfLine() {
  Token Next = NextToken();
  switch (Next.getKind()) {
  default: return false;
  case tok::kw_short:
  case tok::kw_long:
  case tok::kw_signed:
  case tok::kw_unsigned:
  case tok::kw_void:
  case tok::kw_char:
  case tok::kw_int:
  case tok::kw_float:
  case tok::kw_double:
  case tok::kw_bool:
  case tok::kw__Bool:
  case tok::kw___bool:
  case tok::kw___pixel:
    Tok.setKind(tok::kw___vector);
    return true;
  case tok::identifier:
    if (Next.getIdentifierInfo() == Ident_pixel) {
      Tok.setKind(tok::kw___vector);
      return true;
    }
    if (Next.getIdentifierInfo() == Ident_bool ||
        Next.getIdentifierInfo() == Ident_Bool) {
      Tok.setKind(tok::kw___vector);
      return true;
    }
    return false;
  }
}

bool Parser::TryAltiVecTokenOutOfLine(DeclSpec &DS, SourceLocation Loc,
                                      const char *&PrevSpec, unsigned &DiagID,
                                      bool &isInvalid) {
  const PrintingPolicy &Policy = Actions.getASTContext().getPrintingPolicy();
  if (Tok.getIdentifierInfo() == Ident_vector) {
    Token Next = NextToken();
    switch (Next.getKind()) {
    case tok::kw_short:
    case tok::kw_long:
    case tok::kw_signed:
    case tok::kw_unsigned:
    case tok::kw_void:
    case tok::kw_char:
    case tok::kw_int:
    case tok::kw_float:
    case tok::kw_double:
    case tok::kw_bool:
    case tok::kw__Bool:
    case tok::kw___bool:
    case tok::kw___pixel:
      isInvalid = DS.SetTypeAltiVecVector(true, Loc, PrevSpec, DiagID, Policy);
      return true;
    case tok::identifier:
      if (Next.getIdentifierInfo() == Ident_pixel) {
        isInvalid = DS.SetTypeAltiVecVector(true, Loc, PrevSpec, DiagID,Policy);
        return true;
      }
      if (Next.getIdentifierInfo() == Ident_bool ||
          Next.getIdentifierInfo() == Ident_Bool) {
        isInvalid =
            DS.SetTypeAltiVecVector(true, Loc, PrevSpec, DiagID, Policy);
        return true;
      }
      break;
    default:
      break;
    }
  } else if ((Tok.getIdentifierInfo() == Ident_pixel) &&
             DS.isTypeAltiVecVector()) {
    isInvalid = DS.SetTypeAltiVecPixel(true, Loc, PrevSpec, DiagID, Policy);
    return true;
  } else if ((Tok.getIdentifierInfo() == Ident_bool) &&
             DS.isTypeAltiVecVector()) {
    isInvalid = DS.SetTypeAltiVecBool(true, Loc, PrevSpec, DiagID, Policy);
    return true;
  }
  return false;
}

TypeResult Parser::ParseTypeFromString(StringRef TypeStr, StringRef Context,
                                       SourceLocation IncludeLoc) {
  // Consume (unexpanded) tokens up to the end-of-directive.
  SmallVector<Token, 4> Tokens;
  {
    // Create a new buffer from which we will parse the type.
    auto &SourceMgr = PP.getSourceManager();
    FileID FID = SourceMgr.createFileID(
        llvm::MemoryBuffer::getMemBufferCopy(TypeStr, Context), SrcMgr::C_User,
        0, 0, IncludeLoc);

    // Form a new lexer that references the buffer.
    Lexer L(FID, SourceMgr.getBufferOrFake(FID), PP);
    L.setParsingPreprocessorDirective(true);

    // Lex the tokens from that buffer.
    Token Tok;
    do {
      L.Lex(Tok);
      Tokens.push_back(Tok);
    } while (Tok.isNot(tok::eod));
  }

  // Replace the "eod" token with an "eof" token identifying the end of
  // the provided string.
  Token &EndToken = Tokens.back();
  EndToken.startToken();
  EndToken.setKind(tok::eof);
  EndToken.setLocation(Tok.getLocation());
  EndToken.setEofData(TypeStr.data());

  // Add the current token back.
  Tokens.push_back(Tok);

  // Enter the tokens into the token stream.
  PP.EnterTokenStream(Tokens, /*DisableMacroExpansion=*/false,
                      /*IsReinject=*/false);

  // Consume the current token so that we'll start parsing the tokens we
  // added to the stream.
  ConsumeAnyToken();

  // Enter a new scope.
  ParseScope LocalScope(this, 0);

  // Parse the type.
  TypeResult Result = ParseTypeName(nullptr);

  // Check if we parsed the whole thing.
  if (Result.isUsable() &&
      (Tok.isNot(tok::eof) || Tok.getEofData() != TypeStr.data())) {
    Diag(Tok.getLocation(), diag::err_type_unparsed);
  }

  // There could be leftover tokens (e.g. because of an error).
  // Skip through until we reach the 'end of directive' token.
  while (Tok.isNot(tok::eof))
    ConsumeAnyToken();

  // Consume the end token.
  if (Tok.is(tok::eof) && Tok.getEofData() == TypeStr.data())
    ConsumeAnyToken();
  return Result;
}

void Parser::DiagnoseBitIntUse(const Token &Tok) {
  // If the token is for _ExtInt, diagnose it as being deprecated. Otherwise,
  // the token is about _BitInt and gets (potentially) diagnosed as use of an
  // extension.
  assert(Tok.isOneOf(tok::kw__ExtInt, tok::kw__BitInt) &&
         "expected either an _ExtInt or _BitInt token!");

  SourceLocation Loc = Tok.getLocation();
  if (Tok.is(tok::kw__ExtInt)) {
    Diag(Loc, diag::warn_ext_int_deprecated)
        << FixItHint::CreateReplacement(Loc, "_BitInt");
  } else {
    // In C23 mode, diagnose that the use is not compatible with pre-C23 modes.
    // Otherwise, diagnose that the use is a Clang extension.
    if (getLangOpts().C23)
      Diag(Loc, diag::warn_c23_compat_keyword) << Tok.getName();
    else
      Diag(Loc, diag::ext_bit_int) << getLangOpts().CPlusPlus;
  }
}