ParseCXXInlineMethods.cpp

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//===--- ParseCXXInlineMethods.cpp - C++ class inline methods parsing------===//
//
// 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 parsing for C++ class inline methods.
//
//===----------------------------------------------------------------------===//
 
#include "clang/AST/DeclTemplate.h"
#include "clang/Basic/DiagnosticParse.h"
#include "clang/Basic/DiagnosticSema.h"
#include "clang/Parse/Parser.h"
#include "clang/Parse/RAIIObjectsForParser.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/EnterExpressionEvaluationContext.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Scope.h"
#include "llvm/ADT/ScopeExit.h"
 
using namespace clang;
 
StringLiteral *Parser::ParseCXXDeletedFunctionMessage() {
  if (!Tok.is(tok::l_paren))
    return nullptr;
  StringLiteral *Message = nullptr;
  BalancedDelimiterTracker BT{*this, tok::l_paren};
  BT.consumeOpen();
 
  if (isTokenStringLiteral()) {
    ExprResult Res = ParseUnevaluatedStringLiteralExpression();
    if (Res.isUsable()) {
      Message = Res.getAs<StringLiteral>();
      DiagCompat(Message->getBeginLoc(), diag_compat::delete_with_message)
          << Message->getSourceRange();
    }
  } else {
    Diag(Tok.getLocation(), diag::err_expected_string_literal)
        << /*Source='in'*/ 0 << "'delete'";
    SkipUntil(tok::r_paren, StopAtSemi | StopBeforeMatch);
  }
 
  BT.consumeClose();
  return Message;
}
 
void Parser::SkipDeletedFunctionBody() {
  if (!Tok.is(tok::l_paren))
    return;
 
  BalancedDelimiterTracker BT{*this, tok::l_paren};
  BT.consumeOpen();
 
  // Just skip to the end of the current declaration.
  SkipUntil(tok::r_paren, tok::comma, StopAtSemi | StopBeforeMatch);
  if (Tok.is(tok::r_paren))
    BT.consumeClose();
}
 
NamedDecl *Parser::ParseCXXInlineMethodDef(
    AccessSpecifier AS, const ParsedAttributesView &AccessAttrs,
    ParsingDeclarator &D, const ParsedTemplateInfo &TemplateInfo,
    const VirtSpecifiers &VS, SourceLocation PureSpecLoc) {
  assert(D.isFunctionDeclarator() && "This isn't a function declarator!");
  assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try, tok::equal) &&
         "Current token not a '{', ':', '=', or 'try'!");
 
  MultiTemplateParamsArg TemplateParams(
      TemplateInfo.TemplateParams ? TemplateInfo.TemplateParams->data()
                                  : nullptr,
      TemplateInfo.TemplateParams ? TemplateInfo.TemplateParams->size() : 0);
 
  NamedDecl *FnD;
  if (D.getDeclSpec().isFriendSpecified())
    FnD = Actions.ActOnFriendFunctionDecl(getCurScope(), D,
                                          TemplateParams);
  else {
    FnD = Actions.ActOnCXXMemberDeclarator(getCurScope(), AS, D,
                                           TemplateParams, nullptr,
                                           VS, ICIS_NoInit);
    if (FnD) {
      Actions.ProcessDeclAttributeList(getCurScope(), FnD, AccessAttrs);
      if (PureSpecLoc.isValid())
        Actions.ActOnPureSpecifier(FnD, PureSpecLoc);
    }
  }
 
  if (FnD)
    HandleMemberFunctionDeclDelays(D, FnD);
 
  D.complete(FnD);
 
  if (TryConsumeToken(tok::equal)) {
    if (!FnD) {
      SkipUntil(tok::semi);
      return nullptr;
    }
 
    bool Delete = false;
    SourceLocation KWLoc;
    if (TryConsumeToken(tok::kw_delete, KWLoc)) {
      DiagCompat(KWLoc, diag_compat::defaulted_deleted_function)
          << 1 /* deleted */;
      StringLiteral *Message = ParseCXXDeletedFunctionMessage();
      Actions.SetDeclDeleted(FnD, KWLoc, Message);
      Delete = true;
      if (auto *DeclAsFunction = dyn_cast<FunctionDecl>(FnD)) {
        DeclAsFunction->setRangeEnd(PrevTokLocation);
      }
    } else if (TryConsumeToken(tok::kw_default, KWLoc)) {
      DiagCompat(KWLoc, diag_compat::defaulted_deleted_function)
          << 0 /* defaulted */;
      Actions.SetDeclDefaulted(FnD, KWLoc);
      if (auto *DeclAsFunction = dyn_cast<FunctionDecl>(FnD)) {
        DeclAsFunction->setRangeEnd(PrevTokLocation);
      }
    } else {
      llvm_unreachable("function definition after = not 'delete' or 'default'");
    }
 
    if (Tok.is(tok::comma)) {
      Diag(KWLoc, diag::err_default_delete_in_multiple_declaration)
        << Delete;
      SkipUntil(tok::semi);
    } else if (ExpectAndConsume(tok::semi, diag::err_expected_after,
                                Delete ? "delete" : "default") &&
               !isLikelyAtStartOfNewDeclaration()) {
      SkipUntil(tok::semi);
    }
 
    return FnD;
  }
 
  if (SkipFunctionBodies && (!FnD || Actions.canSkipFunctionBody(FnD)) &&
      trySkippingFunctionBody()) {
    Actions.ActOnSkippedFunctionBody(FnD);
    return FnD;
  }
 
  // In delayed template parsing mode, if we are within a class template
  // or if we are about to parse function member template then consume
  // the tokens and store them for parsing at the end of the translation unit.
  if (getLangOpts().DelayedTemplateParsing &&
      D.getFunctionDefinitionKind() == FunctionDefinitionKind::Definition &&
      !D.getDeclSpec().hasConstexprSpecifier() &&
      !(FnD && FnD->getAsFunction() &&
        FnD->getAsFunction()->getReturnType()->getContainedAutoType()) &&
      ((Actions.CurContext->isDependentContext() ||
        (TemplateInfo.Kind != ParsedTemplateKind::NonTemplate &&
         TemplateInfo.Kind != ParsedTemplateKind::ExplicitSpecialization)) &&
       !Actions.IsInsideALocalClassWithinATemplateFunction())) {
 
    CachedTokens Toks;
    LexTemplateFunctionForLateParsing(Toks);
 
    if (FnD) {
      FunctionDecl *FD = FnD->getAsFunction();
      Actions.CheckForFunctionRedefinition(FD);
      Actions.MarkAsLateParsedTemplate(FD, FnD, Toks);
    }
 
    return FnD;
  }
 
  // Consume the tokens and store them for later parsing.
 
  LexedMethod* LM = new LexedMethod(this, FnD);
  getCurrentClass().LateParsedDeclarations.push_back(LM);
  CachedTokens &Toks = LM->Toks;
 
  tok::TokenKind kind = Tok.getKind();
  // Consume everything up to (and including) the left brace of the
  // function body.
  if (ConsumeAndStoreFunctionPrologue(Toks)) {
    // We didn't find the left-brace we expected after the
    // constructor initializer.
 
    // If we're code-completing and the completion point was in the broken
    // initializer, we want to parse it even though that will fail.
    if (PP.isCodeCompletionEnabled() &&
        llvm::any_of(Toks, [](const Token &Tok) {
          return Tok.is(tok::code_completion);
        })) {
      // If we gave up at the completion point, the initializer list was
      // likely truncated, so don't eat more tokens. We'll hit some extra
      // errors, but they should be ignored in code completion.
      return FnD;
    }
 
    // We already printed an error, and it's likely impossible to recover,
    // so don't try to parse this method later.
    // Skip over the rest of the decl and back to somewhere that looks
    // reasonable.
    SkipMalformedDecl();
    delete getCurrentClass().LateParsedDeclarations.back();
    getCurrentClass().LateParsedDeclarations.pop_back();
    return FnD;
  } else {
    // Consume everything up to (and including) the matching right brace.
    ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
  }
 
  // If we're in a function-try-block, we need to store all the catch blocks.
  if (kind == tok::kw_try) {
    while (Tok.is(tok::kw_catch)) {
      ConsumeAndStoreUntil(tok::l_brace, Toks, /*StopAtSemi=*/false);
      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
    }
  }
 
  if (FnD) {
    FunctionDecl *FD = FnD->getAsFunction();
    // Track that this function will eventually have a body; Sema needs
    // to know this.
    Actions.CheckForFunctionRedefinition(FD);
    FD->setWillHaveBody(true);
  } else {
    // If semantic analysis could not build a function declaration,
    // just throw away the late-parsed declaration.
    delete getCurrentClass().LateParsedDeclarations.back();
    getCurrentClass().LateParsedDeclarations.pop_back();
  }
 
  return FnD;
}
 
void Parser::ParseCXXNonStaticMemberInitializer(Decl *VarD) {
  assert(Tok.isOneOf(tok::l_brace, tok::equal) &&
         "Current token not a '{' or '='!");
 
  LateParsedMemberInitializer *MI =
    new LateParsedMemberInitializer(this, VarD);
  getCurrentClass().LateParsedDeclarations.push_back(MI);
  CachedTokens &Toks = MI->Toks;
 
  tok::TokenKind kind = Tok.getKind();
  if (kind == tok::equal) {
    Toks.push_back(Tok);
    ConsumeToken();
  }
 
  if (kind == tok::l_brace) {
    // Begin by storing the '{' token.
    Toks.push_back(Tok);
    ConsumeBrace();
 
    // Consume everything up to (and including) the matching right brace.
    ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/true);
  } else {
    // Consume everything up to (but excluding) the comma or semicolon.
    ConsumeAndStoreInitializer(Toks, CachedInitKind::DefaultInitializer);
  }
 
  // Store an artificial EOF token to ensure that we don't run off the end of
  // the initializer when we come to parse it.
  Token Eof = Token::createEof(Tok.getLocation(), VarD);
  Toks.push_back(Eof);
}
 
LateParsedDeclaration::~LateParsedDeclaration() {}
void LateParsedDeclaration::ParseLexedMethodDeclarations() {}
void LateParsedDeclaration::ParseLexedMemberInitializers() {}
void LateParsedDeclaration::ParseLexedMethodDefs() {}
void LateParsedDeclaration::ParseLexedAttributes() {}
void LateParsedDeclaration::ParseLexedPragmas() {}
 
Parser::LateParsedClass::LateParsedClass(Parser *P, ParsingClass *C)
  : Self(P), Class(C) {}
 
Parser::LateParsedClass::~LateParsedClass() {
  Self->DeallocateParsedClasses(Class);
}
 
void Parser::LateParsedClass::ParseLexedMethodDeclarations() {
  Self->ParseLexedMethodDeclarations(*Class);
}
 
void Parser::LateParsedClass::ParseLexedMemberInitializers() {
  Self->ParseLexedMemberInitializers(*Class);
}
 
void Parser::LateParsedClass::ParseLexedMethodDefs() {
  Self->ParseLexedMethodDefs(*Class);
}
 
void Parser::LateParsedClass::ParseLexedAttributes() {
  Self->ParseLexedAttributes(*Class);
}
 
void Parser::LateParsedClass::ParseLexedPragmas() {
  Self->ParseLexedPragmas(*Class);
}
 
void Parser::LateParsedMethodDeclaration::ParseLexedMethodDeclarations() {
  Self->ParseLexedMethodDeclaration(*this);
}
 
void Parser::LexedMethod::ParseLexedMethodDefs() {
  Self->ParseLexedMethodDef(*this);
}
 
void Parser::LateParsedMemberInitializer::ParseLexedMemberInitializers() {
  Self->ParseLexedMemberInitializer(*this);
}
 
void LateParsedAttribute::ParseLexedAttributes() {
  Self->ParseLexedAttribute(*this, true, false);
}
 
void LateParsedTypeAttribute::ParseLexedAttributes() {}
 
void Parser::LateParsedPragma::ParseLexedPragmas() {
  Self->ParseLexedPragma(*this);
}
 
struct Parser::ReenterTemplateScopeRAII {
  Parser &P;
  MultiParseScope Scopes;
  TemplateParameterDepthRAII CurTemplateDepthTracker;
 
  ReenterTemplateScopeRAII(Parser &P, Decl *MaybeTemplated, bool Enter = true)
      : P(P), Scopes(P), CurTemplateDepthTracker(P.TemplateParameterDepth) {
    if (Enter) {
      CurTemplateDepthTracker.addDepth(
          P.ReenterTemplateScopes(Scopes, MaybeTemplated));
    }
  }
};
 
struct Parser::ReenterClassScopeRAII : ReenterTemplateScopeRAII {
  ParsingClass &Class;
 
  ReenterClassScopeRAII(Parser &P, ParsingClass &Class)
      : ReenterTemplateScopeRAII(P, Class.TagOrTemplate,
                                 /*Enter=*/!Class.TopLevelClass),
        Class(Class) {
    // If this is the top-level class, we're still within its scope.
    if (Class.TopLevelClass)
      return;
 
    // Re-enter the class scope itself.
    Scopes.Enter(Scope::ClassScope|Scope::DeclScope);
    P.Actions.ActOnStartDelayedMemberDeclarations(P.getCurScope(),
                                                  Class.TagOrTemplate);
  }
  ~ReenterClassScopeRAII() {
    if (Class.TopLevelClass)
      return;
 
    P.Actions.ActOnFinishDelayedMemberDeclarations(P.getCurScope(),
                                                   Class.TagOrTemplate);
  }
};
 
void Parser::ParseLexedMethodDeclarations(ParsingClass &Class) {
  ReenterClassScopeRAII InClassScope(*this, Class);
 
  for (LateParsedDeclaration *LateD : Class.LateParsedDeclarations)
    LateD->ParseLexedMethodDeclarations();
}
 
void Parser::ParseLexedMethodDeclaration(LateParsedMethodDeclaration &LM) {
  // If this is a member template, introduce the template parameter scope.
  ReenterTemplateScopeRAII InFunctionTemplateScope(*this, LM.Method);
 
  // Start the delayed C++ method declaration
  Actions.ActOnStartDelayedCXXMethodDeclaration(getCurScope(), LM.Method);
 
  // Introduce the parameters into scope and parse their default
  // arguments.
  InFunctionTemplateScope.Scopes.Enter(Scope::FunctionPrototypeScope |
                                       Scope::FunctionDeclarationScope |
                                       Scope::DeclScope);
 
  // Delayed default arguments or exception specifications may contain lambdas,
  // struct S {
  //   void ICE(int x, int = sizeof([x] { return x; }()));
  // }
  //
  // struct X {
  //   void ICE(int val) noexcept(noexcept([val]{}));
  // };
  // Lambda capture handling in tryCaptureVariable() expects an enclosing
  // function scope in Sema's FunctionScopes stack.
  Sema::FunctionScopeRAII PopFnContext(Actions);
  Actions.PushFunctionScope();
 
  for (unsigned I = 0, N = LM.DefaultArgs.size(); I != N; ++I) {
    auto Param = cast<ParmVarDecl>(LM.DefaultArgs[I].Param);
    // Introduce the parameter into scope.
    bool HasUnparsed = Param->hasUnparsedDefaultArg();
    Actions.ActOnDelayedCXXMethodParameter(getCurScope(), Param);
    std::unique_ptr<CachedTokens> Toks = std::move(LM.DefaultArgs[I].Toks);
    if (Toks) {
      ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
      // Mark the end of the default argument so that we know when to stop when
      // we parse it later on.
      Token LastDefaultArgToken = Toks->back();
      Token DefArgEnd =
          Token::createEof(LastDefaultArgToken.getEndLoc(), Param);
      Toks->push_back(DefArgEnd);
 
      // Parse the default argument from its saved token stream.
      Toks->push_back(Tok); // So that the current token doesn't get lost
      PP.EnterTokenStream(*Toks, true, /*IsReinject*/ true);
 
      // Consume the previously-pushed token.
      ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
 
      // Consume the '='.
      assert(Tok.is(tok::equal) && "Default argument not starting with '='");
      SourceLocation EqualLoc = 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::compat_cxx11_generalized_initializer_lists);
        DefArgResult = ParseBraceInitializer();
      } else
        DefArgResult = ParseAssignmentExpression();
      if (DefArgResult.isInvalid()) {
        Actions.ActOnParamDefaultArgumentError(Param, EqualLoc,
                                               /*DefaultArg=*/nullptr);
      } else {
        if (Tok.isNot(tok::eof) || Tok.getEofData() != Param) {
          // The last two tokens are the terminator and the saved value of
          // Tok; the last token in the default argument is the one before
          // those.
          assert(Toks->size() >= 3 && "expected a token in default arg");
          Diag(Tok.getLocation(), diag::err_default_arg_unparsed)
            << SourceRange(Tok.getLocation(),
                           (*Toks)[Toks->size() - 3].getLocation());
        }
        Actions.ActOnParamDefaultArgument(Param, EqualLoc,
                                          DefArgResult.get());
      }
 
      // There could be leftover tokens (e.g. because of an error).
      // Skip through until we reach the 'end of default argument' token.
      while (Tok.isNot(tok::eof))
        ConsumeAnyToken();
 
      if (Tok.is(tok::eof) && Tok.getEofData() == Param)
        ConsumeAnyToken();
    } else if (HasUnparsed) {
      assert(Param->hasInheritedDefaultArg());
      FunctionDecl *Old;
      if (const auto *FunTmpl = dyn_cast<FunctionTemplateDecl>(LM.Method))
        Old =
            cast<FunctionDecl>(FunTmpl->getTemplatedDecl())->getPreviousDecl();
      else
        Old = cast<FunctionDecl>(LM.Method)->getPreviousDecl();
      if (Old) {
        ParmVarDecl *OldParam = Old->getParamDecl(I);
        assert(!OldParam->hasUnparsedDefaultArg());
        if (OldParam->hasUninstantiatedDefaultArg())
          Param->setUninstantiatedDefaultArg(
              OldParam->getUninstantiatedDefaultArg());
        else
          Param->setDefaultArg(OldParam->getInit());
      }
    }
  }
 
  // Parse a delayed exception-specification, if there is one.
  if (CachedTokens *Toks = LM.ExceptionSpecTokens) {
    ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
    // Add the 'stop' token.
    Token LastExceptionSpecToken = Toks->back();
    Token ExceptionSpecEnd =
        Token::createEof(LastExceptionSpecToken.getEndLoc(), LM.Method);
    Toks->push_back(ExceptionSpecEnd);
 
    // Parse the default argument from its saved token stream.
    Toks->push_back(Tok); // So that the current token doesn't get lost
    PP.EnterTokenStream(*Toks, true, /*IsReinject*/true);
 
    // Consume the previously-pushed token.
    ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
 
    // 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.
    CXXMethodDecl *Method;
    FunctionDecl *FunctionToPush;
    if (FunctionTemplateDecl *FunTmpl
          = dyn_cast<FunctionTemplateDecl>(LM.Method))
      FunctionToPush = FunTmpl->getTemplatedDecl();
    else
      FunctionToPush = cast<FunctionDecl>(LM.Method);
    Method = dyn_cast<CXXMethodDecl>(FunctionToPush);
 
    // Setup the CurScope to match the function DeclContext - we have such
    // assumption in IsInFnTryBlockHandler().
    ParseScope FnScope(this, Scope::FnScope);
    Sema::ContextRAII FnContext(Actions, FunctionToPush,
                                /*NewThisContext=*/false);
 
    Sema::CXXThisScopeRAII ThisScope(
        Actions, Method ? Method->getParent() : nullptr,
        Method ? Method->getMethodQualifiers() : Qualifiers{},
        Method && getLangOpts().CPlusPlus11);
 
    // Parse the exception-specification.
    SourceRange SpecificationRange;
    SmallVector<ParsedType, 4> DynamicExceptions;
    SmallVector<SourceRange, 4> DynamicExceptionRanges;
    ExprResult NoexceptExpr;
    CachedTokens *ExceptionSpecTokens;
 
    ExceptionSpecificationType EST
      = tryParseExceptionSpecification(/*Delayed=*/false, SpecificationRange,
                                       DynamicExceptions,
                                       DynamicExceptionRanges, NoexceptExpr,
                                       ExceptionSpecTokens);
 
    if (Tok.isNot(tok::eof) || Tok.getEofData() != LM.Method)
      Diag(Tok.getLocation(), diag::err_except_spec_unparsed);
 
    // Attach the exception-specification to the method.
    Actions.actOnDelayedExceptionSpecification(LM.Method, EST,
                                               SpecificationRange,
                                               DynamicExceptions,
                                               DynamicExceptionRanges,
                                               NoexceptExpr.isUsable()?
                                                 NoexceptExpr.get() : nullptr);
 
    // There could be leftover tokens (e.g. because of an error).
    // Skip through until we reach the original token position.
    while (Tok.isNot(tok::eof))
      ConsumeAnyToken();
 
    // Clean up the remaining EOF token.
    if (Tok.is(tok::eof) && Tok.getEofData() == LM.Method)
      ConsumeAnyToken();
 
    delete Toks;
    LM.ExceptionSpecTokens = nullptr;
  }
 
  InFunctionTemplateScope.Scopes.Exit();
 
  // Finish the delayed C++ method declaration.
  Actions.ActOnFinishDelayedCXXMethodDeclaration(getCurScope(), LM.Method);
}
 
void Parser::ParseLexedMethodDefs(ParsingClass &Class) {
  ReenterClassScopeRAII InClassScope(*this, Class);
 
  for (LateParsedDeclaration *D : Class.LateParsedDeclarations)
    D->ParseLexedMethodDefs();
}
 
void Parser::ParseLexedMethodDef(LexedMethod &LM) {
  // If this is a member template, introduce the template parameter scope.
  ReenterTemplateScopeRAII InFunctionTemplateScope(*this, LM.D);
 
  ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
  assert(!LM.Toks.empty() && "Empty body!");
  Token LastBodyToken = LM.Toks.back();
  Token BodyEnd = Token::createEof(LastBodyToken.getEndLoc(), LM.D);
  LM.Toks.push_back(BodyEnd);
  // Append the current token at the end of the new token stream so that it
  // doesn't get lost.
  LM.Toks.push_back(Tok);
  PP.EnterTokenStream(LM.Toks, true, /*IsReinject*/true);
 
  // Consume the previously pushed token.
  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
  assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try)
         && "Inline method not starting with '{', ':' or 'try'");
 
  // Parse the method body. Function body parsing code is similar enough
  // to be re-used for method bodies as well.
  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
                               Scope::CompoundStmtScope);
  Sema::FPFeaturesStateRAII SaveFPFeatures(Actions);
 
  Actions.ActOnStartOfFunctionDef(getCurScope(), LM.D);
 
  llvm::scope_exit _([&]() {
    while (Tok.isNot(tok::eof))
      ConsumeAnyToken();
 
    if (Tok.is(tok::eof) && Tok.getEofData() == LM.D)
      ConsumeAnyToken();
 
    if (auto *FD = dyn_cast_or_null<FunctionDecl>(LM.D))
      if (isa<CXXMethodDecl>(FD) ||
          FD->isInIdentifierNamespace(Decl::IDNS_OrdinaryFriend))
        Actions.ActOnFinishInlineFunctionDef(FD);
  });
 
  assert((Actions.getDiagnostics().hasErrorOccurred() ||
          !isa<FunctionTemplateDecl>(LM.D) ||
          cast<FunctionTemplateDecl>(LM.D)->getTemplateParameters()->getDepth()
            < TemplateParameterDepth) &&
         "TemplateParameterDepth should be greater than the depth of "
         "current template being instantiated!");
 
  ParseFunctionBody(LM.D, FnScope);
}
 
void Parser::ParseLexedMemberInitializers(ParsingClass &Class) {
  ReenterClassScopeRAII InClassScope(*this, Class);
 
  if (!Class.LateParsedDeclarations.empty()) {
    // C++11 [expr.prim.general]p4:
    //   Otherwise, if a member-declarator declares a non-static data member
    //  (9.2) of a class X, the expression this is a prvalue of type "pointer
    //  to X" within the optional brace-or-equal-initializer. It shall not
    //  appear elsewhere in the member-declarator.
    // FIXME: This should be done in ParseLexedMemberInitializer, not here.
    Sema::CXXThisScopeRAII ThisScope(Actions, Class.TagOrTemplate,
                                     Qualifiers());
 
    for (LateParsedDeclaration *D : Class.LateParsedDeclarations)
      D->ParseLexedMemberInitializers();
  }
 
  Actions.ActOnFinishDelayedMemberInitializers(Class.TagOrTemplate);
}
 
void Parser::ParseLexedMemberInitializer(LateParsedMemberInitializer &MI) {
  if (!MI.Field || MI.Field->isInvalidDecl())
    return;
 
  ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
  // Append the current token at the end of the new token stream so that it
  // doesn't get lost.
  MI.Toks.push_back(Tok);
  PP.EnterTokenStream(MI.Toks, true, /*IsReinject*/true);
 
  // Consume the previously pushed token.
  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
 
  SourceLocation EqualLoc;
 
  Actions.ActOnStartCXXInClassMemberInitializer();
 
  // The initializer isn't actually potentially evaluated unless it is
  // used.
  EnterExpressionEvaluationContext Eval(
      Actions, Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed);
 
  ExprResult Init = ParseCXXMemberInitializer(MI.Field, /*IsFunction=*/false,
                                              EqualLoc);
 
  Actions.ActOnFinishCXXInClassMemberInitializer(MI.Field, EqualLoc, Init);
 
  // The next token should be our artificial terminating EOF token.
  if (Tok.isNot(tok::eof)) {
    if (!Init.isInvalid()) {
      SourceLocation EndLoc = PP.getLocForEndOfToken(PrevTokLocation);
      if (!EndLoc.isValid())
        EndLoc = Tok.getLocation();
      // No fixit; we can't recover as if there were a semicolon here.
      Diag(EndLoc, diag::err_expected_semi_decl_list);
    }
 
    // Consume tokens until we hit the artificial EOF.
    while (Tok.isNot(tok::eof))
      ConsumeAnyToken();
  }
  // Make sure this is *our* artificial EOF token.
  if (Tok.getEofData() == MI.Field)
    ConsumeAnyToken();
}
 
void Parser::ParseLexedAttributes(ParsingClass &Class) {
  ReenterClassScopeRAII InClassScope(*this, Class);
 
  for (LateParsedDeclaration *LateD : Class.LateParsedDeclarations)
    LateD->ParseLexedAttributes();
}
 
void Parser::ParseLexedAttributeList(LateParsedAttrList &LAs, Decl *D,
                                     bool EnterScope, bool OnDefinition,
                                     ParsedAttributes *OutAttrs) {
  assert(LAs.parseSoon() &&
         "Attribute list should be marked for immediate parsing.");
  for (unsigned i = 0, ni = LAs.size(); i < ni; ++i) {
    if (D)
      LAs[i]->addDecl(D);
    ParseLexedAttribute(*LAs[i], EnterScope, OnDefinition, OutAttrs);
    delete LAs[i];
  }
  LAs.clear();
}
 
/// Collect the references to parameters in \p Attrs' arguments.
static void collectParamRefs(const ParsedAttributes &Attrs,
                             SmallVectorImpl<const DeclRefExpr *> &Refs) {
  SmallVector<const Stmt *, 8> Worklist;
  for (const ParsedAttr &AL : Attrs)
    for (unsigned I = 0, E = AL.getNumArgs(); I != E; ++I)
      if (AL.isArgExpr(I))
        Worklist.push_back(AL.getArgAsExpr(I));
  while (!Worklist.empty()) {
    const Stmt *S = Worklist.pop_back_val();
    if (!S)
      continue;
    if (const auto *DRE = dyn_cast<DeclRefExpr>(S);
        DRE && isa<ParmVarDecl>(DRE->getDecl()))
      Refs.push_back(DRE);
    llvm::append_range(Worklist, S->children());
  }
}
 
bool Parser::checkLateAttributeParamRefs(
    const LateParsedAttribute &LPA, const Decl *D,
    ArrayRef<const DeclRefExpr *> ParamRefs, bool ReenteredProtoParams) {
  auto IsPointeeParam = [&](const ParmVarDecl *PVD) {
    return ReenteredProtoParams && llvm::is_contained(LPA.ProtoParams, PVD);
  };
 
  // In a C++ class, attributes were always late parsed and a pointee's
  // parameters were not in scope, so a name that now binds to one used to bind
  // to whatever else it names outside the prototype. Rather than silently
  // change its meaning, reject the attribute as ambiguous.
  if (getLangOpts().CPlusPlus && getCurScope()->isClassScope()) {
    for (const DeclRefExpr *DRE : ParamRefs) {
      const auto *PVD = cast<ParmVarDecl>(DRE->getDecl());
      if (!IsPointeeParam(PVD))
        continue;
      LookupResult R(Actions, PVD->getDeclName(), DRE->getLocation(),
                     Sema::LookupOrdinaryName);
      if (!Actions.LookupName(R, getCurScope()) || R.isAmbiguous())
        continue;
      Diag(DRE->getLocation(), diag::err_ambiguous_reference)
          << PVD->getDeclName();
      Diag(PVD->getLocation(), diag::note_ambiguous_candidate) << PVD;
      for (const NamedDecl *Other : R)
        Diag(Other->getLocation(), diag::note_ambiguous_candidate) << Other;
      return true;
    }
  }
 
  // A name binds the same way in a template, but instantiation cannot yet map a
  // pointee's parameters, which are instantiated with the declaration's type
  // and not kept, nor a parameter declared after the one the attribute is on,
  // which is instantiated after that parameter's attributes. Reject the
  // attribute rather than instantiate it wrongly.
  // FIXME: Map these parameters during template instantiation.
  if (Actions.CurContext->isDependentContext() ||
      getCurScope()->getTemplateParamParent() ||
      Actions.getCurGenericLambda()) {
    const auto *DParam = dyn_cast_or_null<ParmVarDecl>(D);
    for (const DeclRefExpr *DRE : ParamRefs) {
      const auto *PVD = cast<ParmVarDecl>(DRE->getDecl());
      bool Pointee = IsPointeeParam(PVD);
      if (!Pointee &&
          !(DParam &&
            DParam->getFunctionScopeDepth() == PVD->getFunctionScopeDepth() &&
            DParam->getFunctionScopeIndex() < PVD->getFunctionScopeIndex()))
        continue;
      Diag(DRE->getLocation(), diag::err_late_attribute_param_in_template)
          << &LPA.AttrName << !Pointee << PVD;
      return true;
    }
  }
  return false;
}
 
void Parser::ParseLexedAttribute(LateParsedAttribute &LPA, bool EnterScope,
                                 bool OnDefinition,
                                 ParsedAttributes *OutAttrs) {
  ParsedAttributes Attrs(AttrFactory);
 
  if (LPA.Decls.size() > 0) {
    Decl *D = LPA.Decls[0];
    bool HasFuncScope = EnterScope && LPA.Decls.size() == 1 &&
                        D->isFunctionOrFunctionTemplate();
    bool IsCPlusPlus = getLangOpts().CPlusPlus;
 
    NamedDecl *ND = dyn_cast<NamedDecl>(D);
    RecordDecl *RD = dyn_cast_or_null<RecordDecl>(D->getDeclContext());
 
    // Allow 'this' within late-parsed attributes.
    Sema::CXXThisScopeRAII ThisScope(Actions, RD, Qualifiers(),
                                     IsCPlusPlus && ND &&
                                         ND->isCXXInstanceMember());
 
    // If the Decl is templatized, add template parameters to the scope.
    ReenterTemplateScopeRAII InDeclScope(*this, D, IsCPlusPlus && EnterScope);
 
    // If the Decl is on a function, add function parameters to the scope.
    if (HasFuncScope) {
      InDeclScope.Scopes.Enter(Scope::FnScope | Scope::DeclScope |
                               Scope::CompoundStmtScope);
      Actions.ActOnReenterFunctionContext(Actions.CurScope, D);
    }
 
    // For a function pointer field or variable, the arguments may name a
    // parameter of the pointee. Re-enter them in a prototype scope nested as it
    // was when the attribute was written, so they shadow any outer declaration
    // of the same name. In a C struct, ActOnIdExpression finds the struct's
    // members only while its scope is innermost, so add the parameters to that
    // scope instead; it lets them shadow a member of the same name.
    bool HasProtoParams = !HasFuncScope && !LPA.ProtoParams.empty();
    bool InCStruct = !IsCPlusPlus && getCurScope()->isClassScope();
    ParseScope ProtoScope(this,
                          Scope::FunctionPrototypeScope | Scope::DeclScope,
                          HasProtoParams && !InCStruct);
    if (HasProtoParams)
      Actions.ActOnReenterFunctionPrototypeParams(Actions.getCurScope(),
                                                  LPA.ProtoParams);
 
    ParsedAttributes Parsed = ParseLexedAttributeTokens(LPA);
 
    if (HasProtoParams && InCStruct)
      Actions.ActOnExitFunctionPrototypeParams(Actions.getCurScope(),
                                               LPA.ProtoParams);
    ProtoScope.Exit();
 
    SmallVector<const DeclRefExpr *, 4> ParamRefs;
    collectParamRefs(Parsed, ParamRefs);
    if (!ParamRefs.empty() &&
        checkLateAttributeParamRefs(LPA, D, ParamRefs, HasProtoParams))
      Parsed.clear();
    Attrs.takeAllAppendingFrom(Parsed);
 
    if (HasFuncScope)
      Actions.ActOnExitFunctionContext();
  } else {
    Diag(LPA.AttrNameLoc, diag::warn_attribute_no_decl)
        << LPA.AttrName.getName();
  }
 
  if (OnDefinition && !Attrs.empty() && !Attrs.begin()->isCXX11Attribute() &&
      Attrs.begin()->isKnownToGCC())
    Diag(Tok, diag::warn_attribute_on_function_definition) << &LPA.AttrName;
 
  for (auto *D : LPA.Decls)
    Actions.ActOnFinishDelayedAttribute(getCurScope(), D, Attrs);
 
  if (OutAttrs)
    OutAttrs->takeAllAppendingFrom(Attrs);
}
 
void Parser::ParseLexedPragmas(ParsingClass &Class) {
  ReenterClassScopeRAII InClassScope(*this, Class);
 
  for (LateParsedDeclaration *D : Class.LateParsedDeclarations)
    D->ParseLexedPragmas();
}
 
void Parser::ParseLexedPragma(LateParsedPragma &LP) {
  PP.EnterToken(Tok, /*IsReinject=*/true);
  PP.EnterTokenStream(LP.toks(), /*DisableMacroExpansion=*/true,
                      /*IsReinject=*/true);
 
  // Consume the previously pushed token.
  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
  assert(Tok.isAnnotation() && "Expected annotation token.");
  switch (Tok.getKind()) {
  case tok::annot_attr_openmp:
  case tok::annot_pragma_openmp: {
    AccessSpecifier AS = LP.getAccessSpecifier();
    ParsedAttributes Attrs(AttrFactory);
    (void)ParseOpenMPDeclarativeDirectiveWithExtDecl(AS, Attrs);
    break;
  }
  default:
    llvm_unreachable("Unexpected token.");
  }
}
 
bool Parser::ConsumeAndStoreUntil(tok::TokenKind T1, tok::TokenKind T2,
                                  CachedTokens &Toks,
                                  bool StopAtSemi, bool ConsumeFinalToken) {
  // We always want this function to consume at least one token if the first
  // token isn't T and if not at EOF.
  bool isFirstTokenConsumed = true;
  while (true) {
    // If we found one of the tokens, stop and return true.
    if (Tok.is(T1) || Tok.is(T2)) {
      if (ConsumeFinalToken) {
        Toks.push_back(Tok);
        ConsumeAnyToken();
      }
      return true;
    }
 
    switch (Tok.getKind()) {
    case tok::eof:
    case tok::annot_module_begin:
    case tok::annot_module_end:
    case tok::annot_module_include:
    case tok::annot_repl_input_end:
      // Ran out of tokens.
      return false;
 
    case tok::annot_pragma_openacc:
    case tok::annot_pragma_openmp:
    case tok::annot_attr_openmp: {
      // Ignore any tokens inside of a OMP/OpenACC pragma, as these should just
      // be taken as 1.
      tok::TokenKind EndKind = Tok.is(tok::annot_pragma_openacc)
                                   ? tok::annot_pragma_openacc_end
                                   : tok::annot_pragma_openmp_end;
      Toks.push_back(Tok);
      ConsumeAnnotationToken();
      while (Tok.isNot(EndKind) && Tok.isNot(tok::eof)) {
        Toks.push_back(Tok);
        ConsumeAnyToken();
      }
      if (Tok.is(EndKind)) {
        Toks.push_back(Tok);
        ConsumeAnnotationToken();
      }
      break;
    }
 
    case tok::l_paren:
      // Recursively consume properly-nested parens.
      Toks.push_back(Tok);
      ConsumeParen();
      ConsumeAndStoreUntil(tok::r_paren, Toks, /*StopAtSemi=*/false);
      break;
    case tok::l_square:
      // Recursively consume properly-nested square brackets.
      Toks.push_back(Tok);
      ConsumeBracket();
      ConsumeAndStoreUntil(tok::r_square, Toks, /*StopAtSemi=*/false);
      break;
    case tok::l_brace:
      // Recursively consume properly-nested braces.
      Toks.push_back(Tok);
      ConsumeBrace();
      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
      break;
 
    // Okay, we found a ']' or '}' or ')', which we think should be balanced.
    // Since the user wasn't looking for this token (if they were, it would
    // already be handled), this isn't balanced.  If there is a LHS token at a
    // higher level, we will assume that this matches the unbalanced token
    // and return it.  Otherwise, this is a spurious RHS token, which we skip.
    case tok::r_paren:
      if (ParenCount && !isFirstTokenConsumed)
        return false;  // Matches something.
      Toks.push_back(Tok);
      ConsumeParen();
      break;
    case tok::r_square:
      if (BracketCount && !isFirstTokenConsumed)
        return false;  // Matches something.
      Toks.push_back(Tok);
      ConsumeBracket();
      break;
    case tok::r_brace:
      if (BraceCount && !isFirstTokenConsumed)
        return false;  // Matches something.
      Toks.push_back(Tok);
      ConsumeBrace();
      break;
 
    case tok::semi:
      if (StopAtSemi)
        return false;
      [[fallthrough]];
    default:
      // consume this token.
      Toks.push_back(Tok);
      ConsumeAnyToken(/*ConsumeCodeCompletionTok*/true);
      break;
    }
    isFirstTokenConsumed = false;
  }
}
 
bool Parser::ConsumeAndStoreFunctionPrologue(CachedTokens &Toks) {
  if (Tok.is(tok::kw_try)) {
    Toks.push_back(Tok);
    ConsumeToken();
  }
 
  if (Tok.isNot(tok::colon)) {
    // Easy case, just a function body.
 
    // Grab any remaining garbage to be diagnosed later. We stop when we reach a
    // brace: an opening one is the function body, while a closing one probably
    // means we've reached the end of the class.
    ConsumeAndStoreUntil(tok::l_brace, tok::r_brace, Toks,
                         /*StopAtSemi=*/true,
                         /*ConsumeFinalToken=*/false);
    if (Tok.isNot(tok::l_brace))
      return Diag(Tok.getLocation(), diag::err_expected) << tok::l_brace;
 
    Toks.push_back(Tok);
    ConsumeBrace();
    return false;
  }
 
  Toks.push_back(Tok);
  ConsumeToken();
 
  // We can't reliably skip over a mem-initializer-id, because it could be
  // a template-id involving not-yet-declared names. Given:
  //
  //   S ( ) : a < b < c > ( e )
  //
  // 'e' might be an initializer or part of a template argument, depending
  // on whether 'b' is a template.
 
  // Track whether we might be inside a template argument. We can give
  // significantly better diagnostics if we know that we're not.
  bool MightBeTemplateArgument = false;
 
  while (true) {
    // Skip over the mem-initializer-id, if possible.
    if (Tok.is(tok::kw_decltype)) {
      Toks.push_back(Tok);
      SourceLocation OpenLoc = ConsumeToken();
      if (Tok.isNot(tok::l_paren))
        return Diag(Tok.getLocation(), diag::err_expected_lparen_after)
                 << "decltype";
      Toks.push_back(Tok);
      ConsumeParen();
      if (!ConsumeAndStoreUntil(tok::r_paren, Toks, /*StopAtSemi=*/true)) {
        Diag(Tok.getLocation(), diag::err_expected) << tok::r_paren;
        Diag(OpenLoc, diag::note_matching) << tok::l_paren;
        return true;
      }
    }
    do {
      // Walk over a component of a nested-name-specifier.
      if (Tok.is(tok::coloncolon)) {
        Toks.push_back(Tok);
        ConsumeToken();
 
        if (Tok.is(tok::kw_template)) {
          Toks.push_back(Tok);
          ConsumeToken();
        }
      }
 
      if (Tok.is(tok::identifier)) {
        Toks.push_back(Tok);
        ConsumeToken();
      } else {
        break;
      }
      // Pack indexing
      if (Tok.is(tok::ellipsis) && NextToken().is(tok::l_square)) {
        Toks.push_back(Tok);
        SourceLocation OpenLoc = ConsumeToken();
        Toks.push_back(Tok);
        ConsumeBracket();
        if (!ConsumeAndStoreUntil(tok::r_square, Toks, /*StopAtSemi=*/true)) {
          Diag(Tok.getLocation(), diag::err_expected) << tok::r_square;
          Diag(OpenLoc, diag::note_matching) << tok::l_square;
          return true;
        }
      }
 
    } while (Tok.is(tok::coloncolon));
 
    if (Tok.is(tok::code_completion)) {
      Toks.push_back(Tok);
      ConsumeCodeCompletionToken();
      if (Tok.isOneOf(tok::identifier, tok::coloncolon, tok::kw_decltype)) {
        // Could be the start of another member initializer (the ',' has not
        // been written yet)
        continue;
      }
    }
 
    if (Tok.is(tok::comma)) {
      // The initialization is missing, we'll diagnose it later.
      Toks.push_back(Tok);
      ConsumeToken();
      continue;
    }
    if (Tok.is(tok::less))
      MightBeTemplateArgument = true;
 
    if (MightBeTemplateArgument) {
      // We may be inside a template argument list. Grab up to the start of the
      // next parenthesized initializer or braced-init-list. This *might* be the
      // initializer, or it might be a subexpression in the template argument
      // list.
      // FIXME: Count angle brackets, and clear MightBeTemplateArgument
      //        if all angles are closed.
      if (!ConsumeAndStoreUntil(tok::l_paren, tok::l_brace, Toks,
                                /*StopAtSemi=*/true,
                                /*ConsumeFinalToken=*/false)) {
        // We're not just missing the initializer, we're also missing the
        // function body!
        return Diag(Tok.getLocation(), diag::err_expected) << tok::l_brace;
      }
    } else if (Tok.isNot(tok::l_paren) && Tok.isNot(tok::l_brace)) {
      // We found something weird in a mem-initializer-id.
      if (getLangOpts().CPlusPlus11)
        return Diag(Tok.getLocation(), diag::err_expected_either)
               << tok::l_paren << tok::l_brace;
      else
        return Diag(Tok.getLocation(), diag::err_expected) << tok::l_paren;
    }
 
    tok::TokenKind kind = Tok.getKind();
    Toks.push_back(Tok);
    bool IsLParen = (kind == tok::l_paren);
    SourceLocation OpenLoc = Tok.getLocation();
 
    if (IsLParen) {
      ConsumeParen();
    } else {
      assert(kind == tok::l_brace && "Must be left paren or brace here.");
      ConsumeBrace();
      // In C++03, this has to be the start of the function body, which
      // means the initializer is malformed; we'll diagnose it later.
      if (!getLangOpts().CPlusPlus11)
        return false;
 
      const Token &PreviousToken = Toks[Toks.size() - 2];
      if (!MightBeTemplateArgument &&
          !PreviousToken.isOneOf(tok::identifier, tok::greater,
                                 tok::greatergreater)) {
        // If the opening brace is not preceded by one of these tokens, we are
        // missing the mem-initializer-id. In order to recover better, we need
        // to use heuristics to determine if this '{' is most likely the
        // beginning of a brace-init-list or the function body.
        // Check the token after the corresponding '}'.
        TentativeParsingAction PA(*this);
        if (SkipUntil(tok::r_brace) &&
            !Tok.isOneOf(tok::comma, tok::ellipsis, tok::l_brace)) {
          // Consider there was a malformed initializer and this is the start
          // of the function body. We'll diagnose it later.
          PA.Revert();
          return false;
        }
        PA.Revert();
      }
    }
 
    // Grab the initializer (or the subexpression of the template argument).
    // FIXME: If we support lambdas here, we'll need to set StopAtSemi to false
    //        if we might be inside the braces of a lambda-expression.
    tok::TokenKind CloseKind = IsLParen ? tok::r_paren : tok::r_brace;
    if (!ConsumeAndStoreUntil(CloseKind, Toks, /*StopAtSemi=*/true)) {
      Diag(Tok, diag::err_expected) << CloseKind;
      Diag(OpenLoc, diag::note_matching) << kind;
      return true;
    }
 
    // Grab pack ellipsis, if present.
    if (Tok.is(tok::ellipsis)) {
      Toks.push_back(Tok);
      ConsumeToken();
    }
 
    // If we know we just consumed a mem-initializer, we must have ',' or '{'
    // next.
    if (Tok.is(tok::comma)) {
      Toks.push_back(Tok);
      ConsumeToken();
    } else if (Tok.is(tok::l_brace)) {
      // This is the function body if the ')' or '}' is immediately followed by
      // a '{'. That cannot happen within a template argument, apart from the
      // case where a template argument contains a compound literal:
      //
      //   S ( ) : a < b < c > ( d ) { }
      //   // End of declaration, or still inside the template argument?
      //
      // ... and the case where the template argument contains a lambda:
      //
      //   S ( ) : a < 0 && b < c > ( d ) + [ ] ( ) { return 0; }
      //     ( ) > ( ) { }
      //
      // FIXME: Disambiguate these cases. Note that the latter case is probably
      //        going to be made ill-formed by core issue 1607.
      Toks.push_back(Tok);
      ConsumeBrace();
      return false;
    } else if (!MightBeTemplateArgument) {
      return Diag(Tok.getLocation(), diag::err_expected_either) << tok::l_brace
                                                                << tok::comma;
    }
  }
}
 
bool Parser::ConsumeAndStoreConditional(CachedTokens &Toks) {
  // Consume '?'.
  assert(Tok.is(tok::question));
  Toks.push_back(Tok);
  ConsumeToken();
 
  while (Tok.isNot(tok::colon)) {
    if (!ConsumeAndStoreUntil(tok::question, tok::colon, Toks,
                              /*StopAtSemi=*/true,
                              /*ConsumeFinalToken=*/false))
      return false;
 
    // If we found a nested conditional, consume it.
    if (Tok.is(tok::question) && !ConsumeAndStoreConditional(Toks))
      return false;
  }
 
  // Consume ':'.
  Toks.push_back(Tok);
  ConsumeToken();
  return true;
}
 
bool Parser::ConsumeAndStoreInitializer(CachedTokens &Toks,
                                        CachedInitKind CIK) {
  // We always want this function to consume at least one token if not at EOF.
  bool IsFirstToken = true;
 
  // Number of possible unclosed <s we've seen so far. These might be templates,
  // and might not, but if there were none of them (or we know for sure that
  // we're within a template), we can avoid a tentative parse.
  unsigned AngleCount = 0;
  unsigned KnownTemplateCount = 0;
 
  while (true) {
    switch (Tok.getKind()) {
    case tok::ellipsis:
      // We found an elipsis at the end of the parameter list;
      // it is not part of a parameter declaration.
      if (ParenCount == 1 && NextToken().is(tok::r_paren))
        return true;
      goto consume_token;
    case tok::comma:
      // If we might be in a template, perform a tentative parse to check.
      if (!AngleCount)
        // Not a template argument: this is the end of the initializer.
        return true;
      if (KnownTemplateCount)
        goto consume_token;
 
      // We hit a comma inside angle brackets. This is the hard case. The
      // rule we follow is:
      //  * For a default argument, if the tokens after the comma form a
      //    syntactically-valid parameter-declaration-clause, in which each
      //    parameter has an initializer, then this comma ends the default
      //    argument.
      //  * For a default initializer, if the tokens after the comma form a
      //    syntactically-valid init-declarator-list, then this comma ends
      //    the default initializer.
      {
        TentativeParsingAction TPA(*this, /*Unannotated=*/true);
        Sema::TentativeAnalysisScope Scope(Actions);
 
        TPResult Result = TPResult::Error;
        ConsumeToken();
        switch (CIK) {
        case CachedInitKind::DefaultInitializer:
          Result = TryParseInitDeclaratorList();
          // If we parsed a complete, ambiguous init-declarator-list, this
          // is only syntactically-valid if it's followed by a semicolon.
          if (Result == TPResult::Ambiguous && Tok.isNot(tok::semi))
            Result = TPResult::False;
          break;
 
        case CachedInitKind::DefaultArgument:
          bool InvalidAsDeclaration = false;
          Result = TryParseParameterDeclarationClause(
              &InvalidAsDeclaration, /*VersusTemplateArg=*/true);
          // If this is an expression or a declaration with a missing
          // 'typename', assume it's not a declaration.
          if (Result == TPResult::Ambiguous && InvalidAsDeclaration)
            Result = TPResult::False;
          break;
        }
 
        // Put the token stream back and undo any annotations we performed
        // after the comma. They may reflect a different parse than the one
        // we will actually perform at the end of the class.
        TPA.Revert();
 
        // If what follows could be a declaration, it is a declaration.
        if (Result != TPResult::False && Result != TPResult::Error)
          return true;
      }
 
      // Keep going. We know we're inside a template argument list now.
      ++KnownTemplateCount;
      goto consume_token;
 
    case tok::eof:
      // Ran out of tokens.
      return false;
 
    case tok::less:
      // FIXME: A '<' can only start a template-id if it's preceded by an
      // identifier, an operator-function-id, or a literal-operator-id.
      ++AngleCount;
      goto consume_token;
 
    case tok::question:
      // In 'a ? b : c', 'b' can contain an unparenthesized comma. If it does,
      // that is *never* the end of the initializer. Skip to the ':'.
      if (!ConsumeAndStoreConditional(Toks))
        return false;
      break;
 
    case tok::greatergreatergreater:
      if (!getLangOpts().CPlusPlus11)
        goto consume_token;
      if (AngleCount) --AngleCount;
      if (KnownTemplateCount) --KnownTemplateCount;
      [[fallthrough]];
    case tok::greatergreater:
      if (!getLangOpts().CPlusPlus11)
        goto consume_token;
      if (AngleCount) --AngleCount;
      if (KnownTemplateCount) --KnownTemplateCount;
      [[fallthrough]];
    case tok::greater:
      if (AngleCount) --AngleCount;
      if (KnownTemplateCount) --KnownTemplateCount;
      goto consume_token;
 
    case tok::kw_template:
      // 'template' identifier '<' is known to start a template argument list,
      // and can be used to disambiguate the parse.
      // FIXME: Support all forms of 'template' unqualified-id '<'.
      Toks.push_back(Tok);
      ConsumeToken();
      if (Tok.is(tok::identifier)) {
        Toks.push_back(Tok);
        ConsumeToken();
        if (Tok.is(tok::less)) {
          ++AngleCount;
          ++KnownTemplateCount;
          Toks.push_back(Tok);
          ConsumeToken();
        }
      }
      break;
 
    case tok::kw_operator:
      // If 'operator' precedes other punctuation, that punctuation loses
      // its special behavior.
      Toks.push_back(Tok);
      ConsumeToken();
      switch (Tok.getKind()) {
      case tok::comma:
      case tok::greatergreatergreater:
      case tok::greatergreater:
      case tok::greater:
      case tok::less:
        Toks.push_back(Tok);
        ConsumeToken();
        break;
      default:
        break;
      }
      break;
 
    case tok::l_paren:
      // Recursively consume properly-nested parens.
      Toks.push_back(Tok);
      ConsumeParen();
      ConsumeAndStoreUntil(tok::r_paren, Toks, /*StopAtSemi=*/false);
      break;
    case tok::l_square:
      // Recursively consume properly-nested square brackets.
      Toks.push_back(Tok);
      ConsumeBracket();
      ConsumeAndStoreUntil(tok::r_square, Toks, /*StopAtSemi=*/false);
      break;
    case tok::l_brace:
      // Recursively consume properly-nested braces.
      Toks.push_back(Tok);
      ConsumeBrace();
      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
      break;
 
    // Okay, we found a ']' or '}' or ')', which we think should be balanced.
    // Since the user wasn't looking for this token (if they were, it would
    // already be handled), this isn't balanced.  If there is a LHS token at a
    // higher level, we will assume that this matches the unbalanced token
    // and return it.  Otherwise, this is a spurious RHS token, which we
    // consume and pass on to downstream code to diagnose.
    case tok::r_paren:
      if (CIK == CachedInitKind::DefaultArgument)
        return true; // End of the default argument.
      if (ParenCount && !IsFirstToken)
        return false;
      Toks.push_back(Tok);
      ConsumeParen();
      continue;
    case tok::r_square:
      if (BracketCount && !IsFirstToken)
        return false;
      Toks.push_back(Tok);
      ConsumeBracket();
      continue;
    case tok::r_brace:
      if (BraceCount && !IsFirstToken)
        return false;
      Toks.push_back(Tok);
      ConsumeBrace();
      continue;
 
    case tok::code_completion:
      Toks.push_back(Tok);
      ConsumeCodeCompletionToken();
      break;
 
    case tok::string_literal:
    case tok::wide_string_literal:
    case tok::utf8_string_literal:
    case tok::utf16_string_literal:
    case tok::utf32_string_literal:
      Toks.push_back(Tok);
      ConsumeStringToken();
      break;
    case tok::semi:
      if (CIK == CachedInitKind::DefaultInitializer)
        return true; // End of the default initializer.
      [[fallthrough]];
    default:
    consume_token:
      // If it's an annotation token, then we've run out of tokens and should
      // bail out. Otherwise, cache the token and consume it.
      if (Tok.isAnnotation())
        return false;
 
      Toks.push_back(Tok);
      ConsumeToken();
      break;
    }
    IsFirstToken = false;
  }
}