/usr/src/gnu/usr.bin/clang/libclangParse/../../../llvm/clang/lib/Parse/ParseTemplate.cpp

Bug Summary

File:	src/gnu/usr.bin/clang/libclangParse/../../../llvm/clang/lib/Parse/ParseTemplate.cpp
Warning:	line 1679, column 51 Called C++ object pointer is null
Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ParseTemplate.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangParse/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libclangParse/../../../llvm/clang/include -I /usr/src/gnu/usr.bin/clang/libclangParse/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libclangParse/../include -I /usr/src/gnu/usr.bin/clang/libclangParse/obj -I /usr/src/gnu/usr.bin/clang/libclangParse/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libclangParse/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libclangParse/../../../llvm/clang/lib/Parse/ParseTemplate.cpp
1//===--- ParseTemplate.cpp - Template Parsing -----------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file implements parsing of C++ templates.
10//
11//===----------------------------------------------------------------------===//

13#include "clang/AST/ASTContext.h"
14#include "clang/AST/DeclTemplate.h"
15#include "clang/AST/ExprCXX.h"
16#include "clang/Parse/ParseDiagnostic.h"
17#include "clang/Parse/Parser.h"
18#include "clang/Parse/RAIIObjectsForParser.h"
19#include "clang/Sema/DeclSpec.h"
20#include "clang/Sema/ParsedTemplate.h"
21#include "clang/Sema/Scope.h"
22#include "llvm/Support/TimeProfiler.h"
23using namespace clang;

25/// Re-enter a possible template scope, creating as many template parameter
26/// scopes as necessary.
27/// \return The number of template parameter scopes entered.
28unsigned Parser::ReenterTemplateScopes(MultiParseScope &S, Decl *D) {
return Actions.ActOnReenterTemplateScope(D, [&] {
  S.Enter(Scope::TemplateParamScope);
  return Actions.getCurScope();
});
33}

35/// Parse a template declaration, explicit instantiation, or
36/// explicit specialization.
37Decl *Parser::ParseDeclarationStartingWithTemplate(
  DeclaratorContext Context, SourceLocation &DeclEnd,
  ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
ObjCDeclContextSwitch ObjCDC(*this);

if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less)) {
  return ParseExplicitInstantiation(Context, SourceLocation(), ConsumeToken(),
                                    DeclEnd, AccessAttrs, AS);
}
return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AccessAttrs,
                                                AS);
48}

50/// Parse a template declaration or an explicit specialization.
51///
52/// Template declarations include one or more template parameter lists
53/// and either the function or class template declaration. Explicit
54/// specializations contain one or more 'template < >' prefixes
55/// followed by a (possibly templated) declaration. Since the
56/// syntactic form of both features is nearly identical, we parse all
57/// of the template headers together and let semantic analysis sort
58/// the declarations from the explicit specializations.
59///
60///       template-declaration: [C++ temp]
61///         'export'[opt] 'template' '<' template-parameter-list '>' declaration
62///
63///       template-declaration: [C++2a]
64///         template-head declaration
65///         template-head concept-definition
66///
67///       TODO: requires-clause
68///       template-head: [C++2a]
69///         'template' '<' template-parameter-list '>'
70///             requires-clause[opt]
71///
72///       explicit-specialization: [ C++ temp.expl.spec]
73///         'template' '<' '>' declaration
74Decl *Parser::ParseTemplateDeclarationOrSpecialization(
  DeclaratorContext Context, SourceLocation &DeclEnd,
  ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
assert(Tok.isOneOf(tok::kw_export, tok::kw_template) &&((void)0)
       "Token does not start a template declaration.")((void)0);

MultiParseScope TemplateParamScopes(*this);

// Tell the action that names should be checked in the context of
// the declaration to come.
ParsingDeclRAIIObject
  ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);

// Parse multiple levels of template headers within this template
// parameter scope, e.g.,
//
//   template<typename T>
//     template<typename U>
//       class A<T>::B { ... };
//
// We parse multiple levels non-recursively so that we can build a
// single data structure containing all of the template parameter
// lists to easily differentiate between the case above and:
//
//   template<typename T>
//   class A {
//     template<typename U> class B;
//   };
//
// In the first case, the action for declaring A<T>::B receives
// both template parameter lists. In the second case, the action for
// defining A<T>::B receives just the inner template parameter list
// (and retrieves the outer template parameter list from its
// context).
bool isSpecialization = true;
bool LastParamListWasEmpty = false;
TemplateParameterLists ParamLists;
TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);

do {
  // Consume the 'export', if any.
  SourceLocation ExportLoc;
  TryConsumeToken(tok::kw_export, ExportLoc);

  // Consume the 'template', which should be here.
  SourceLocation TemplateLoc;
  if (!TryConsumeToken(tok::kw_template, TemplateLoc)) {
    Diag(Tok.getLocation(), diag::err_expected_template);
    return nullptr;
  }

  // Parse the '<' template-parameter-list '>'
  SourceLocation LAngleLoc, RAngleLoc;
  SmallVector<NamedDecl*, 4> TemplateParams;
  if (ParseTemplateParameters(TemplateParamScopes,
                              CurTemplateDepthTracker.getDepth(),
                              TemplateParams, LAngleLoc, RAngleLoc)) {
    // Skip until the semi-colon or a '}'.
    SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
    TryConsumeToken(tok::semi);
    return nullptr;
  }

  ExprResult OptionalRequiresClauseConstraintER;
  if (!TemplateParams.empty()) {
    isSpecialization = false;
    ++CurTemplateDepthTracker;

    if (TryConsumeToken(tok::kw_requires)) {
      OptionalRequiresClauseConstraintER =
          Actions.ActOnRequiresClause(ParseConstraintLogicalOrExpression(
              /*IsTrailingRequiresClause=*/false));
      if (!OptionalRequiresClauseConstraintER.isUsable()) {
        // Skip until the semi-colon or a '}'.
        SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
        TryConsumeToken(tok::semi);
        return nullptr;
      }
    }
  } else {
    LastParamListWasEmpty = true;
  }

  ParamLists.push_back(Actions.ActOnTemplateParameterList(
      CurTemplateDepthTracker.getDepth(), ExportLoc, TemplateLoc, LAngleLoc,
      TemplateParams, RAngleLoc, OptionalRequiresClauseConstraintER.get()));
} while (Tok.isOneOf(tok::kw_export, tok::kw_template));

// Parse the actual template declaration.
if (Tok.is(tok::kw_concept))
  return ParseConceptDefinition(
      ParsedTemplateInfo(&ParamLists, isSpecialization,
                         LastParamListWasEmpty),
      DeclEnd);

return ParseSingleDeclarationAfterTemplate(
    Context,
    ParsedTemplateInfo(&ParamLists, isSpecialization, LastParamListWasEmpty),
    ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
173}

175/// Parse a single declaration that declares a template,
176/// template specialization, or explicit instantiation of a template.
177///
178/// \param DeclEnd will receive the source location of the last token
179/// within this declaration.
180///
181/// \param AS the access specifier associated with this
182/// declaration. Will be AS_none for namespace-scope declarations.
183///
184/// \returns the new declaration.
185Decl *Parser::ParseSingleDeclarationAfterTemplate(
  DeclaratorContext Context, const ParsedTemplateInfo &TemplateInfo,
  ParsingDeclRAIIObject &DiagsFromTParams, SourceLocation &DeclEnd,
  ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&((void)0)
       "Template information required")((void)0);

if (Tok.is(tok::kw_static_assert)) {
  // A static_assert declaration may not be templated.
  Diag(Tok.getLocation(), diag::err_templated_invalid_declaration)
    << TemplateInfo.getSourceRange();
  // Parse the static_assert declaration to improve error recovery.
  return ParseStaticAssertDeclaration(DeclEnd);
}

if (Context == DeclaratorContext::Member) {
  // We are parsing a member template.
  ParseCXXClassMemberDeclaration(AS, AccessAttrs, TemplateInfo,
                                 &DiagsFromTParams);
  return nullptr;
}

ParsedAttributesWithRange prefixAttrs(AttrFactory);
MaybeParseCXX11Attributes(prefixAttrs);

if (Tok.is(tok::kw_using)) {
  auto usingDeclPtr = ParseUsingDirectiveOrDeclaration(Context, TemplateInfo, DeclEnd,
                                                       prefixAttrs);
  if (!usingDeclPtr || !usingDeclPtr.get().isSingleDecl())
    return nullptr;
  return usingDeclPtr.get().getSingleDecl();
}

// Parse the declaration specifiers, stealing any diagnostics from
// the template parameters.
ParsingDeclSpec DS(*this, &DiagsFromTParams);

ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
                           getDeclSpecContextFromDeclaratorContext(Context));

if (Tok.is(tok::semi)) {
  ProhibitAttributes(prefixAttrs);
  DeclEnd = ConsumeToken();
  RecordDecl *AnonRecord = nullptr;
  Decl *Decl = Actions.ParsedFreeStandingDeclSpec(
      getCurScope(), AS, DS,
      TemplateInfo.TemplateParams ? *TemplateInfo.TemplateParams
                                  : MultiTemplateParamsArg(),
      TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation,
      AnonRecord);
  assert(!AnonRecord &&((void)0)
         "Anonymous unions/structs should not be valid with template")((void)0);
  DS.complete(Decl);
  return Decl;
}

// Move the attributes from the prefix into the DS.
if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation)
  ProhibitAttributes(prefixAttrs);
else
  DS.takeAttributesFrom(prefixAttrs);

// Parse the declarator.
ParsingDeclarator DeclaratorInfo(*this, DS, (DeclaratorContext)Context);
if (TemplateInfo.TemplateParams)
  DeclaratorInfo.setTemplateParameterLists(*TemplateInfo.TemplateParams);
ParseDeclarator(DeclaratorInfo);
// Error parsing the declarator?
if (!DeclaratorInfo.hasName()) {
  // If so, skip until the semi-colon or a }.
  SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
  if (Tok.is(tok::semi))
    ConsumeToken();
  return nullptr;
}

llvm::TimeTraceScope TimeScope("ParseTemplate", [&]() {
  return std::string(DeclaratorInfo.getIdentifier() != nullptr
                         ? DeclaratorInfo.getIdentifier()->getName()
                         : "<unknown>");
});

LateParsedAttrList LateParsedAttrs(true);
if (DeclaratorInfo.isFunctionDeclarator()) {
  if (Tok.is(tok::kw_requires))
    ParseTrailingRequiresClause(DeclaratorInfo);

  MaybeParseGNUAttributes(DeclaratorInfo, &LateParsedAttrs);
}

if (DeclaratorInfo.isFunctionDeclarator() &&
    isStartOfFunctionDefinition(DeclaratorInfo)) {

  // 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) {
    Diag(Tok, diag::err_function_definition_not_allowed);
    SkipMalformedDecl();
    return nullptr;
  }

  if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
    // Recover by ignoring the 'typedef'. This was probably supposed to be
    // the 'typename' keyword, which we should have already suggested adding
    // if it's appropriate.
    Diag(DS.getStorageClassSpecLoc(), diag::err_function_declared_typedef)
      << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
    DS.ClearStorageClassSpecs();
  }

  if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
    if (DeclaratorInfo.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;
      return ParseFunctionDefinition(DeclaratorInfo, ParsedTemplateInfo(),
                                     &LateParsedAttrs);
    } else {
      SourceLocation LAngleLoc
        = PP.getLocForEndOfToken(TemplateInfo.TemplateLoc);
      Diag(DeclaratorInfo.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, None,
          LAngleLoc, nullptr));

      return ParseFunctionDefinition(
          DeclaratorInfo, ParsedTemplateInfo(&FakedParamLists,
                                             /*isSpecialization=*/true,
                                             /*lastParameterListWasEmpty=*/true),
          &LateParsedAttrs);
    }
  }
  return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo,
                                 &LateParsedAttrs);
}

// Parse this declaration.
Decl *ThisDecl = ParseDeclarationAfterDeclarator(DeclaratorInfo,
                                                 TemplateInfo);

if (Tok.is(tok::comma)) {
  Diag(Tok, diag::err_multiple_template_declarators)
    << (int)TemplateInfo.Kind;
  SkipUntil(tok::semi);
  return ThisDecl;
}

// Eat the semi colon after the declaration.
ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
if (LateParsedAttrs.size() > 0)
  ParseLexedAttributeList(LateParsedAttrs, ThisDecl, true, false);
DeclaratorInfo.complete(ThisDecl);
return ThisDecl;
346}

348/// \brief Parse a single declaration that declares a concept.
349///
350/// \param DeclEnd will receive the source location of the last token
351/// within this declaration.
352///
353/// \returns the new declaration.
354Decl *
355Parser::ParseConceptDefinition(const ParsedTemplateInfo &TemplateInfo,
                             SourceLocation &DeclEnd) {
assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&((void)0)
       "Template information required")((void)0);
assert(Tok.is(tok::kw_concept) &&((void)0)
       "ParseConceptDefinition must be called when at a 'concept' keyword")((void)0);

ConsumeToken(); // Consume 'concept'

SourceLocation BoolKWLoc;
if (TryConsumeToken(tok::kw_bool, BoolKWLoc))
  Diag(Tok.getLocation(), diag::ext_concept_legacy_bool_keyword) <<
      FixItHint::CreateRemoval(SourceLocation(BoolKWLoc));

DiagnoseAndSkipCXX11Attributes();

CXXScopeSpec SS;
if (ParseOptionalCXXScopeSpecifier(
        SS, /*ObjectType=*/nullptr,
        /*ObjectHadErrors=*/false, /*EnteringContext=*/false,
        /*MayBePseudoDestructor=*/nullptr,
        /*IsTypename=*/false, /*LastII=*/nullptr, /*OnlyNamespace=*/true) ||
    SS.isInvalid()) {
  SkipUntil(tok::semi);
  return nullptr;
}

if (SS.isNotEmpty())
  Diag(SS.getBeginLoc(),
       diag::err_concept_definition_not_identifier);

UnqualifiedId Result;
if (ParseUnqualifiedId(SS, /*ObjectType=*/nullptr,
                       /*ObjectHadErrors=*/false, /*EnteringContext=*/false,
                       /*AllowDestructorName=*/false,
                       /*AllowConstructorName=*/false,
                       /*AllowDeductionGuide=*/false,
                       /*TemplateKWLoc=*/nullptr, Result)) {
  SkipUntil(tok::semi);
  return nullptr;
}

if (Result.getKind() != UnqualifiedIdKind::IK_Identifier) {
  Diag(Result.getBeginLoc(), diag::err_concept_definition_not_identifier);
  SkipUntil(tok::semi);
  return nullptr;
}

IdentifierInfo *Id = Result.Identifier;
SourceLocation IdLoc = Result.getBeginLoc();

DiagnoseAndSkipCXX11Attributes();

if (!TryConsumeToken(tok::equal)) {
  Diag(Tok.getLocation(), diag::err_expected) << tok::equal;
  SkipUntil(tok::semi);
  return nullptr;
}

ExprResult ConstraintExprResult =
    Actions.CorrectDelayedTyposInExpr(ParseConstraintExpression());
if (ConstraintExprResult.isInvalid()) {
  SkipUntil(tok::semi);
  return nullptr;
}

DeclEnd = Tok.getLocation();
ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
Expr *ConstraintExpr = ConstraintExprResult.get();
return Actions.ActOnConceptDefinition(getCurScope(),
                                      *TemplateInfo.TemplateParams,
                                      Id, IdLoc, ConstraintExpr);
427}

429/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
430/// angle brackets. Depth is the depth of this template-parameter-list, which
431/// is the number of template headers directly enclosing this template header.
432/// TemplateParams is the current list of template parameters we're building.
433/// The template parameter we parse will be added to this list. LAngleLoc and
434/// RAngleLoc will receive the positions of the '<' and '>', respectively,
435/// that enclose this template parameter list.
436///
437/// \returns true if an error occurred, false otherwise.
438bool Parser::ParseTemplateParameters(
  MultiParseScope &TemplateScopes, unsigned Depth,
  SmallVectorImpl<NamedDecl *> &TemplateParams, SourceLocation &LAngleLoc,
  SourceLocation &RAngleLoc) {
// Get the template parameter list.
if (!TryConsumeToken(tok::less, LAngleLoc)) {
  Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
  return true;
}

// Try to parse the template parameter list.
bool Failed = false;
// FIXME: Missing greatergreatergreater support.
if (!Tok.is(tok::greater) && !Tok.is(tok::greatergreater)) {
  TemplateScopes.Enter(Scope::TemplateParamScope);
  Failed = ParseTemplateParameterList(Depth, TemplateParams);
}

if (Tok.is(tok::greatergreater)) {
  // No diagnostic required here: a template-parameter-list can only be
  // followed by a declaration or, for a template template parameter, the
  // 'class' keyword. Therefore, the second '>' will be diagnosed later.
  // This matters for elegant diagnosis of:
  //   template<template<typename>> struct S;
  Tok.setKind(tok::greater);
  RAngleLoc = Tok.getLocation();
  Tok.setLocation(Tok.getLocation().getLocWithOffset(1));
} else if (!TryConsumeToken(tok::greater, RAngleLoc) && Failed) {
  Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
  return true;
}
return false;
470}

472/// ParseTemplateParameterList - Parse a template parameter list. If
473/// the parsing fails badly (i.e., closing bracket was left out), this
474/// will try to put the token stream in a reasonable position (closing
475/// a statement, etc.) and return false.
476///
477///       template-parameter-list:    [C++ temp]
478///         template-parameter
479///         template-parameter-list ',' template-parameter
480bool
481Parser::ParseTemplateParameterList(const unsigned Depth,
                           SmallVectorImpl<NamedDecl*> &TemplateParams) {
while (1) {

  if (NamedDecl *TmpParam
        = ParseTemplateParameter(Depth, TemplateParams.size())) {
    TemplateParams.push_back(TmpParam);
  } else {
    // If we failed to parse a template parameter, skip until we find
    // a comma or closing brace.
    SkipUntil(tok::comma, tok::greater, tok::greatergreater,
              StopAtSemi | StopBeforeMatch);
  }

  // Did we find a comma or the end of the template parameter list?
  if (Tok.is(tok::comma)) {
    ConsumeToken();
  } else if (Tok.isOneOf(tok::greater, tok::greatergreater)) {
    // Don't consume this... that's done by template parser.
    break;
  } else {
    // Somebody probably forgot to close the template. Skip ahead and
    // try to get out of the expression. This error is currently
    // subsumed by whatever goes on in ParseTemplateParameter.
    Diag(Tok.getLocation(), diag::err_expected_comma_greater);
    SkipUntil(tok::comma, tok::greater, tok::greatergreater,
              StopAtSemi | StopBeforeMatch);
    return false;
  }
}
return true;
512}

514/// Determine whether the parser is at the start of a template
515/// type parameter.
516Parser::TPResult Parser::isStartOfTemplateTypeParameter() {
if (Tok.is(tok::kw_class)) {
  // "class" may be the start of an elaborated-type-specifier or a
  // type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
  switch (NextToken().getKind()) {
  case tok::equal:
  case tok::comma:
  case tok::greater:
  case tok::greatergreater:
  case tok::ellipsis:
    return TPResult::True;

  case tok::identifier:
    // This may be either a type-parameter or an elaborated-type-specifier.
    // We have to look further.
    break;

  default:
    return TPResult::False;
  }

  switch (GetLookAheadToken(2).getKind()) {
  case tok::equal:
  case tok::comma:
  case tok::greater:
  case tok::greatergreater:
    return TPResult::True;

  default:
    return TPResult::False;
  }
}

if (TryAnnotateTypeConstraint())
  return TPResult::Error;

if (isTypeConstraintAnnotation() &&
    // Next token might be 'auto' or 'decltype', indicating that this
    // type-constraint is in fact part of a placeholder-type-specifier of a
    // non-type template parameter.
    !GetLookAheadToken(Tok.is(tok::annot_cxxscope) ? 2 : 1)
         .isOneOf(tok::kw_auto, tok::kw_decltype))
  return TPResult::True;

// 'typedef' is a reasonably-common typo/thinko for 'typename', and is
// ill-formed otherwise.
if (Tok.isNot(tok::kw_typename) && Tok.isNot(tok::kw_typedef))
  return TPResult::False;

// C++ [temp.param]p2:
//   There is no semantic difference between class and typename in a
//   template-parameter. typename followed by an unqualified-id
//   names a template type parameter. typename followed by a
//   qualified-id denotes the type in a non-type
//   parameter-declaration.
Token Next = NextToken();

// If we have an identifier, skip over it.
if (Next.getKind() == tok::identifier)
  Next = GetLookAheadToken(2);

switch (Next.getKind()) {
case tok::equal:
case tok::comma:
case tok::greater:
case tok::greatergreater:
case tok::ellipsis:
  return TPResult::True;

case tok::kw_typename:
case tok::kw_typedef:
case tok::kw_class:
  // These indicate that a comma was missed after a type parameter, not that
  // we have found a non-type parameter.
  return TPResult::True;

default:
  return TPResult::False;
}
595}

597/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
598///
599///       template-parameter: [C++ temp.param]
600///         type-parameter
601///         parameter-declaration
602///
603///       type-parameter: (See below)
604///         type-parameter-key ...[opt] identifier[opt]
605///         type-parameter-key identifier[opt] = type-id
606/// (C++2a) type-constraint ...[opt] identifier[opt]
607/// (C++2a) type-constraint identifier[opt] = type-id
608///         'template' '<' template-parameter-list '>' type-parameter-key
609///               ...[opt] identifier[opt]
610///         'template' '<' template-parameter-list '>' type-parameter-key
611///               identifier[opt] '=' id-expression
612///
613///       type-parameter-key:
614///         class
615///         typename
616///
617NamedDecl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {

switch (isStartOfTemplateTypeParameter()) {
case TPResult::True:
  // Is there just a typo in the input code? ('typedef' instead of
  // 'typename')
  if (Tok.is(tok::kw_typedef)) {
    Diag(Tok.getLocation(), diag::err_expected_template_parameter);

    Diag(Tok.getLocation(), diag::note_meant_to_use_typename)
        << FixItHint::CreateReplacement(CharSourceRange::getCharRange(
                                            Tok.getLocation(),
                                            Tok.getEndLoc()),
                                        "typename");

    Tok.setKind(tok::kw_typename);
  }

  return ParseTypeParameter(Depth, Position);
case TPResult::False:
  break;

case TPResult::Error: {
  // We return an invalid parameter as opposed to null to avoid having bogus
  // diagnostics about an empty template parameter list.
  // FIXME: Fix ParseTemplateParameterList to better handle nullptr results
  //  from here.
  // Return a NTTP as if there was an error in a scope specifier, the user
  // probably meant to write the type of a NTTP.
  DeclSpec DS(getAttrFactory());
  DS.SetTypeSpecError();
  Declarator D(DS, DeclaratorContext::TemplateParam);
  D.SetIdentifier(nullptr, Tok.getLocation());
  D.setInvalidType(true);
  NamedDecl *ErrorParam = Actions.ActOnNonTypeTemplateParameter(
      getCurScope(), D, Depth, Position, /*EqualLoc=*/SourceLocation(),
      /*DefaultArg=*/nullptr);
  ErrorParam->setInvalidDecl(true);
  SkipUntil(tok::comma, tok::greater, tok::greatergreater,
            StopAtSemi | StopBeforeMatch);
  return ErrorParam;
}

case TPResult::Ambiguous:
  llvm_unreachable("template param classification can't be ambiguous")__builtin_unreachable();
}

if (Tok.is(tok::kw_template))
  return ParseTemplateTemplateParameter(Depth, Position);

// If it's none of the above, then it must be a parameter declaration.
// NOTE: This will pick up errors in the closure of the template parameter
// list (e.g., template < ; Check here to implement >> style closures.
return ParseNonTypeTemplateParameter(Depth, Position);
671}

673/// Check whether the current token is a template-id annotation denoting a
674/// type-constraint.
675bool Parser::isTypeConstraintAnnotation() {
const Token &T = Tok.is(tok::annot_cxxscope) ? NextToken() : Tok;
if (T.isNot(tok::annot_template_id))
  return false;
const auto *ExistingAnnot =
    static_cast<TemplateIdAnnotation *>(T.getAnnotationValue());
return ExistingAnnot->Kind == TNK_Concept_template;
682}

684/// Try parsing a type-constraint at the current location.
685///
686///     type-constraint:
687///       nested-name-specifier[opt] concept-name
688///       nested-name-specifier[opt] concept-name
689///           '<' template-argument-list[opt] '>'[opt]
690///
691/// \returns true if an error occurred, and false otherwise.
692bool Parser::TryAnnotateTypeConstraint() {
if (!getLangOpts().CPlusPlus20)
  return false;
CXXScopeSpec SS;
bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
                                   /*ObjectHadErrors=*/false,
                                   /*EnteringContext=*/false,
                                   /*MayBePseudoDestructor=*/nullptr,
                                   // If this is not a type-constraint, then
                                   // this scope-spec is part of the typename
                                   // of a non-type template parameter
                                   /*IsTypename=*/true, /*LastII=*/nullptr,
                                   // We won't find concepts in
                                   // non-namespaces anyway, so might as well
                                   // parse this correctly for possible type
                                   // names.
                                   /*OnlyNamespace=*/false))
  return true;

if (Tok.is(tok::identifier)) {
  UnqualifiedId PossibleConceptName;
  PossibleConceptName.setIdentifier(Tok.getIdentifierInfo(),
                                    Tok.getLocation());

  TemplateTy PossibleConcept;
  bool MemberOfUnknownSpecialization = false;
  auto TNK = Actions.isTemplateName(getCurScope(), SS,
                                    /*hasTemplateKeyword=*/false,
                                    PossibleConceptName,
                                    /*ObjectType=*/ParsedType(),
                                    /*EnteringContext=*/false,
                                    PossibleConcept,
                                    MemberOfUnknownSpecialization,
                                    /*Disambiguation=*/true);
  if (MemberOfUnknownSpecialization || !PossibleConcept ||
      TNK != TNK_Concept_template) {
    if (SS.isNotEmpty())
      AnnotateScopeToken(SS, !WasScopeAnnotation);
    return false;
  }

  // At this point we're sure we're dealing with a constrained parameter. It
  // may or may not have a template parameter list following the concept
  // name.
  if (AnnotateTemplateIdToken(PossibleConcept, TNK, SS,
                                 /*TemplateKWLoc=*/SourceLocation(),
                                 PossibleConceptName,
                                 /*AllowTypeAnnotation=*/false,
                                 /*TypeConstraint=*/true))
    return true;
}

if (SS.isNotEmpty())
  AnnotateScopeToken(SS, !WasScopeAnnotation);
return false;
748}

750/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
751/// Other kinds of template parameters are parsed in
752/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
753///
754///       type-parameter:     [C++ temp.param]
755///         'class' ...[opt][C++0x] identifier[opt]
756///         'class' identifier[opt] '=' type-id
757///         'typename' ...[opt][C++0x] identifier[opt]
758///         'typename' identifier[opt] '=' type-id
759NamedDecl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
assert((Tok.isOneOf(tok::kw_class, tok::kw_typename) ||((void)0)
        isTypeConstraintAnnotation()) &&((void)0)
       "A type-parameter starts with 'class', 'typename' or a "((void)0)
       "type-constraint")((void)0);

CXXScopeSpec TypeConstraintSS;
TemplateIdAnnotation *TypeConstraint = nullptr;
bool TypenameKeyword = false;
SourceLocation KeyLoc;
ParseOptionalCXXScopeSpecifier(TypeConstraintSS, /*ObjectType=*/nullptr,
                               /*ObjectHadErrors=*/false,
                               /*EnteringContext*/ false);
if (Tok.is(tok::annot_template_id)) {
  // Consume the 'type-constraint'.
  TypeConstraint =
      static_cast<TemplateIdAnnotation *>(Tok.getAnnotationValue());
  assert(TypeConstraint->Kind == TNK_Concept_template &&((void)0)
         "stray non-concept template-id annotation")((void)0);
  KeyLoc = ConsumeAnnotationToken();
} else {
  assert(TypeConstraintSS.isEmpty() &&((void)0)
         "expected type constraint after scope specifier")((void)0);

  // Consume the 'class' or 'typename' keyword.
  TypenameKeyword = Tok.is(tok::kw_typename);
  KeyLoc = ConsumeToken();
}

// Grab the ellipsis (if given).
SourceLocation EllipsisLoc;
if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) {
  Diag(EllipsisLoc,
       getLangOpts().CPlusPlus11
         ? diag::warn_cxx98_compat_variadic_templates
         : diag::ext_variadic_templates);
}

// Grab the template parameter name (if given)
SourceLocation NameLoc = Tok.getLocation();
IdentifierInfo *ParamName = nullptr;
if (Tok.is(tok::identifier)) {
  ParamName = Tok.getIdentifierInfo();
  ConsumeToken();
} else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
                       tok::greatergreater)) {
  // Unnamed template parameter. Don't have to do anything here, just
  // don't consume this token.
} else {
  Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
  return nullptr;
}

// Recover from misplaced ellipsis.
bool AlreadyHasEllipsis = EllipsisLoc.isValid();
if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
  DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);

// Grab a default argument (if available).
// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
// we introduce the type parameter into the local scope.
SourceLocation EqualLoc;
ParsedType DefaultArg;
if (TryConsumeToken(tok::equal, EqualLoc))
  DefaultArg =
      ParseTypeName(/*Range=*/nullptr, DeclaratorContext::TemplateTypeArg)
          .get();

NamedDecl *NewDecl = Actions.ActOnTypeParameter(getCurScope(),
                                                TypenameKeyword, EllipsisLoc,
                                                KeyLoc, ParamName, NameLoc,
                                                Depth, Position, EqualLoc,
                                                DefaultArg,
                                                TypeConstraint != nullptr);

if (TypeConstraint) {
  Actions.ActOnTypeConstraint(TypeConstraintSS, TypeConstraint,
                              cast<TemplateTypeParmDecl>(NewDecl),
                              EllipsisLoc);
}

return NewDecl;
841}

843/// ParseTemplateTemplateParameter - Handle the parsing of template
844/// template parameters.
845///
846///       type-parameter:    [C++ temp.param]
847///         'template' '<' template-parameter-list '>' type-parameter-key
848///                  ...[opt] identifier[opt]
849///         'template' '<' template-parameter-list '>' type-parameter-key
850///                  identifier[opt] = id-expression
851///       type-parameter-key:
852///         'class'
853///         'typename'       [C++1z]
854NamedDecl *
855Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
assert(Tok.is(tok::kw_template) && "Expected 'template' keyword")((void)0);

// Handle the template <...> part.
SourceLocation TemplateLoc = ConsumeToken();
SmallVector<NamedDecl*,8> TemplateParams;
SourceLocation LAngleLoc, RAngleLoc;
{
  MultiParseScope TemplateParmScope(*this);
  if (ParseTemplateParameters(TemplateParmScope, Depth + 1, TemplateParams,
                              LAngleLoc, RAngleLoc)) {
    return nullptr;
  }
}

// Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
// Generate a meaningful error if the user forgot to put class before the
// identifier, comma, or greater. Provide a fixit if the identifier, comma,
// or greater appear immediately or after 'struct'. In the latter case,
// replace the keyword with 'class'.
if (!TryConsumeToken(tok::kw_class)) {
  bool Replace = Tok.isOneOf(tok::kw_typename, tok::kw_struct);
  const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
  if (Tok.is(tok::kw_typename)) {
    Diag(Tok.getLocation(),
         getLangOpts().CPlusPlus17
             ? diag::warn_cxx14_compat_template_template_param_typename
             : diag::ext_template_template_param_typename)
      << (!getLangOpts().CPlusPlus17
              ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
              : FixItHint());
  } else if (Next.isOneOf(tok::identifier, tok::comma, tok::greater,
                          tok::greatergreater, tok::ellipsis)) {
    Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
      << (Replace ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
                  : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
  } else
    Diag(Tok.getLocation(), diag::err_class_on_template_template_param);

  if (Replace)
    ConsumeToken();
}

// Parse the ellipsis, if given.
SourceLocation EllipsisLoc;
if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
  Diag(EllipsisLoc,
       getLangOpts().CPlusPlus11
         ? diag::warn_cxx98_compat_variadic_templates
         : diag::ext_variadic_templates);

// Get the identifier, if given.
SourceLocation NameLoc = Tok.getLocation();
IdentifierInfo *ParamName = nullptr;
if (Tok.is(tok::identifier)) {
  ParamName = Tok.getIdentifierInfo();
  ConsumeToken();
} else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
                       tok::greatergreater)) {
  // Unnamed template parameter. Don't have to do anything here, just
  // don't consume this token.
} else {
  Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
  return nullptr;
}

// Recover from misplaced ellipsis.
bool AlreadyHasEllipsis = EllipsisLoc.isValid();
if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
  DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);

TemplateParameterList *ParamList =
  Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
                                     TemplateLoc, LAngleLoc,
                                     TemplateParams,
                                     RAngleLoc, nullptr);

// Grab a default argument (if available).
// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
// we introduce the template parameter into the local scope.
SourceLocation EqualLoc;
ParsedTemplateArgument DefaultArg;
if (TryConsumeToken(tok::equal, EqualLoc)) {
  DefaultArg = ParseTemplateTemplateArgument();
  if (DefaultArg.isInvalid()) {
    Diag(Tok.getLocation(),
         diag::err_default_template_template_parameter_not_template);
    SkipUntil(tok::comma, tok::greater, tok::greatergreater,
              StopAtSemi | StopBeforeMatch);
  }
}

return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
                                              ParamList, EllipsisLoc,
                                              ParamName, NameLoc, Depth,
                                              Position, EqualLoc, DefaultArg);
951}

953/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
954/// template parameters (e.g., in "template<int Size> class array;").
955///
956///       template-parameter:
957///         ...
958///         parameter-declaration
959NamedDecl *
960Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
// Parse the declaration-specifiers (i.e., the type).
// FIXME: The type should probably be restricted in some way... Not all
// declarators (parts of declarators?) are accepted for parameters.
DeclSpec DS(AttrFactory);
ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS_none,
                           DeclSpecContext::DSC_template_param);

// Parse this as a typename.
Declarator ParamDecl(DS, DeclaratorContext::TemplateParam);
ParseDeclarator(ParamDecl);
if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
  Diag(Tok.getLocation(), diag::err_expected_template_parameter);
  return nullptr;
}

// Recover from misplaced ellipsis.
SourceLocation EllipsisLoc;
if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
  DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, ParamDecl);

// If there is a default value, parse it.
// Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
// we introduce the template parameter into the local scope.
SourceLocation EqualLoc;
ExprResult DefaultArg;
if (TryConsumeToken(tok::equal, EqualLoc)) {
  // C++ [temp.param]p15:
  //   When parsing a default template-argument for a non-type
  //   template-parameter, the first non-nested > is taken as the
  //   end of the template-parameter-list rather than a greater-than
  //   operator.
  GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
  EnterExpressionEvaluationContext ConstantEvaluated(
      Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);

  DefaultArg = Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression());
  if (DefaultArg.isInvalid())
    SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
}

// Create the parameter.
return Actions.ActOnNonTypeTemplateParameter(getCurScope(), ParamDecl,
                                             Depth, Position, EqualLoc,
                                             DefaultArg.get());
1005}

1007void Parser::DiagnoseMisplacedEllipsis(SourceLocation EllipsisLoc,
                                     SourceLocation CorrectLoc,
                                     bool AlreadyHasEllipsis,
                                     bool IdentifierHasName) {
FixItHint Insertion;
if (!AlreadyHasEllipsis)
  Insertion = FixItHint::CreateInsertion(CorrectLoc, "...");
Diag(EllipsisLoc, diag::err_misplaced_ellipsis_in_declaration)
    << FixItHint::CreateRemoval(EllipsisLoc) << Insertion
    << !IdentifierHasName;
1017}

1019void Parser::DiagnoseMisplacedEllipsisInDeclarator(SourceLocation EllipsisLoc,
                                                 Declarator &D) {
assert(EllipsisLoc.isValid())((void)0);
bool AlreadyHasEllipsis = D.getEllipsisLoc().isValid();
if (!AlreadyHasEllipsis)
  D.setEllipsisLoc(EllipsisLoc);
DiagnoseMisplacedEllipsis(EllipsisLoc, D.getIdentifierLoc(),
                          AlreadyHasEllipsis, D.hasName());
1027}

1029/// Parses a '>' at the end of a template list.
1030///
1031/// If this function encounters '>>', '>>>', '>=', or '>>=', it tries
1032/// to determine if these tokens were supposed to be a '>' followed by
1033/// '>', '>>', '>=', or '>='. It emits an appropriate diagnostic if necessary.
1034///
1035/// \param RAngleLoc the location of the consumed '>'.
1036///
1037/// \param ConsumeLastToken if true, the '>' is consumed.
1038///
1039/// \param ObjCGenericList if true, this is the '>' closing an Objective-C
1040/// type parameter or type argument list, rather than a C++ template parameter
1041/// or argument list.
1042///
1043/// \returns true, if current token does not start with '>', false otherwise.
1044bool Parser::ParseGreaterThanInTemplateList(SourceLocation LAngleLoc,
                                          SourceLocation &RAngleLoc,
                                          bool ConsumeLastToken,
                                          bool ObjCGenericList) {
// What will be left once we've consumed the '>'.
tok::TokenKind RemainingToken;
const char *ReplacementStr = "> >";
bool MergeWithNextToken = false;

switch (Tok.getKind()) {
default:
  Diag(getEndOfPreviousToken(), diag::err_expected) << tok::greater;
  Diag(LAngleLoc, diag::note_matching) << tok::less;
  return true;

case tok::greater:
  // Determine the location of the '>' token. Only consume this token
  // if the caller asked us to.
  RAngleLoc = Tok.getLocation();
  if (ConsumeLastToken)
    ConsumeToken();
  return false;

case tok::greatergreater:
  RemainingToken = tok::greater;
  break;

case tok::greatergreatergreater:
  RemainingToken = tok::greatergreater;
  break;

case tok::greaterequal:
  RemainingToken = tok::equal;
  ReplacementStr = "> =";

  // Join two adjacent '=' tokens into one, for cases like:
  //   void (*p)() = f<int>;
  //   return f<int>==p;
  if (NextToken().is(tok::equal) &&
      areTokensAdjacent(Tok, NextToken())) {
    RemainingToken = tok::equalequal;
    MergeWithNextToken = true;
  }
  break;

case tok::greatergreaterequal:
  RemainingToken = tok::greaterequal;
  break;
}

// This template-id is terminated by a token that starts with a '>'.
// Outside C++11 and Objective-C, this is now error recovery.
//
// C++11 allows this when the token is '>>', and in CUDA + C++11 mode, we
// extend that treatment to also apply to the '>>>' token.
//
// Objective-C allows this in its type parameter / argument lists.

SourceLocation TokBeforeGreaterLoc = PrevTokLocation;
SourceLocation TokLoc = Tok.getLocation();
Token Next = NextToken();

// Whether splitting the current token after the '>' would undesirably result
// in the remaining token pasting with the token after it. This excludes the
// MergeWithNextToken cases, which we've already handled.
bool PreventMergeWithNextToken =
    (RemainingToken == tok::greater ||
     RemainingToken == tok::greatergreater) &&
    (Next.isOneOf(tok::greater, tok::greatergreater,
                  tok::greatergreatergreater, tok::equal, tok::greaterequal,
                  tok::greatergreaterequal, tok::equalequal)) &&
    areTokensAdjacent(Tok, Next);

// Diagnose this situation as appropriate.
if (!ObjCGenericList) {
  // The source range of the replaced token(s).
  CharSourceRange ReplacementRange = CharSourceRange::getCharRange(
      TokLoc, Lexer::AdvanceToTokenCharacter(TokLoc, 2, PP.getSourceManager(),
                                             getLangOpts()));

  // A hint to put a space between the '>>'s. In order to make the hint as
  // clear as possible, we include the characters either side of the space in
  // the replacement, rather than just inserting a space at SecondCharLoc.
  FixItHint Hint1 = FixItHint::CreateReplacement(ReplacementRange,
                                                 ReplacementStr);

  // A hint to put another space after the token, if it would otherwise be
  // lexed differently.
  FixItHint Hint2;
  if (PreventMergeWithNextToken)
    Hint2 = FixItHint::CreateInsertion(Next.getLocation(), " ");

  unsigned DiagId = diag::err_two_right_angle_brackets_need_space;
  if (getLangOpts().CPlusPlus11 &&
      (Tok.is(tok::greatergreater) || Tok.is(tok::greatergreatergreater)))
    DiagId = diag::warn_cxx98_compat_two_right_angle_brackets;
  else if (Tok.is(tok::greaterequal))
    DiagId = diag::err_right_angle_bracket_equal_needs_space;
  Diag(TokLoc, DiagId) << Hint1 << Hint2;
}

// Find the "length" of the resulting '>' token. This is not always 1, as it
// can contain escaped newlines.
unsigned GreaterLength = Lexer::getTokenPrefixLength(
    TokLoc, 1, PP.getSourceManager(), getLangOpts());

// Annotate the source buffer to indicate that we split the token after the
// '>'. This allows us to properly find the end of, and extract the spelling
// of, the '>' token later.
RAngleLoc = PP.SplitToken(TokLoc, GreaterLength);

// Strip the initial '>' from the token.
bool CachingTokens = PP.IsPreviousCachedToken(Tok);

Token Greater = Tok;
Greater.setLocation(RAngleLoc);
Greater.setKind(tok::greater);
Greater.setLength(GreaterLength);

unsigned OldLength = Tok.getLength();
if (MergeWithNextToken) {
  ConsumeToken();
  OldLength += Tok.getLength();
}

Tok.setKind(RemainingToken);
Tok.setLength(OldLength - GreaterLength);

// Split the second token if lexing it normally would lex a different token
// (eg, the fifth token in 'A<B>>>' should re-lex as '>', not '>>').
SourceLocation AfterGreaterLoc = TokLoc.getLocWithOffset(GreaterLength);
if (PreventMergeWithNextToken)
  AfterGreaterLoc = PP.SplitToken(AfterGreaterLoc, Tok.getLength());
Tok.setLocation(AfterGreaterLoc);

// Update the token cache to match what we just did if necessary.
if (CachingTokens) {
  // If the previous cached token is being merged, delete it.
  if (MergeWithNextToken)
    PP.ReplacePreviousCachedToken({});

  if (ConsumeLastToken)
    PP.ReplacePreviousCachedToken({Greater, Tok});
  else
    PP.ReplacePreviousCachedToken({Greater});
}

if (ConsumeLastToken) {
  PrevTokLocation = RAngleLoc;
} else {
  PrevTokLocation = TokBeforeGreaterLoc;
  PP.EnterToken(Tok, /*IsReinject=*/true);
  Tok = Greater;
}

return false;
1200}


1203/// Parses a template-id that after the template name has
1204/// already been parsed.
1205///
1206/// This routine takes care of parsing the enclosed template argument
1207/// list ('<' template-parameter-list [opt] '>') and placing the
1208/// results into a form that can be transferred to semantic analysis.
1209///
1210/// \param ConsumeLastToken if true, then we will consume the last
1211/// token that forms the template-id. Otherwise, we will leave the
1212/// last token in the stream (e.g., so that it can be replaced with an
1213/// annotation token).
1214bool
1215Parser::ParseTemplateIdAfterTemplateName(bool ConsumeLastToken,
                                       SourceLocation &LAngleLoc,
                                       TemplateArgList &TemplateArgs,
                                       SourceLocation &RAngleLoc) {
assert(Tok.is(tok::less) && "Must have already parsed the template-name")((void)0);

// Consume the '<'.
LAngleLoc = ConsumeToken();

// Parse the optional template-argument-list.
bool Invalid = false;
{
  GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
  if (!Tok.isOneOf(tok::greater, tok::greatergreater,
                   tok::greatergreatergreater, tok::greaterequal,
                   tok::greatergreaterequal))
    Invalid = ParseTemplateArgumentList(TemplateArgs);

  if (Invalid) {
    // Try to find the closing '>'.
    if (getLangOpts().CPlusPlus11)
      SkipUntil(tok::greater, tok::greatergreater,
                tok::greatergreatergreater, StopAtSemi | StopBeforeMatch);
    else
      SkipUntil(tok::greater, StopAtSemi | StopBeforeMatch);
  }
}

return ParseGreaterThanInTemplateList(LAngleLoc, RAngleLoc, ConsumeLastToken,
                                      /*ObjCGenericList=*/false) ||
       Invalid;
1246}

1248/// Replace the tokens that form a simple-template-id with an
1249/// annotation token containing the complete template-id.
1250///
1251/// The first token in the stream must be the name of a template that
1252/// is followed by a '<'. This routine will parse the complete
1253/// simple-template-id and replace the tokens with a single annotation
1254/// token with one of two different kinds: if the template-id names a
1255/// type (and \p AllowTypeAnnotation is true), the annotation token is
1256/// a type annotation that includes the optional nested-name-specifier
1257/// (\p SS). Otherwise, the annotation token is a template-id
1258/// annotation that does not include the optional
1259/// nested-name-specifier.
1260///
1261/// \param Template  the declaration of the template named by the first
1262/// token (an identifier), as returned from \c Action::isTemplateName().
1263///
1264/// \param TNK the kind of template that \p Template
1265/// refers to, as returned from \c Action::isTemplateName().
1266///
1267/// \param SS if non-NULL, the nested-name-specifier that precedes
1268/// this template name.
1269///
1270/// \param TemplateKWLoc if valid, specifies that this template-id
1271/// annotation was preceded by the 'template' keyword and gives the
1272/// location of that keyword. If invalid (the default), then this
1273/// template-id was not preceded by a 'template' keyword.
1274///
1275/// \param AllowTypeAnnotation if true (the default), then a
1276/// simple-template-id that refers to a class template, template
1277/// template parameter, or other template that produces a type will be
1278/// replaced with a type annotation token. Otherwise, the
1279/// simple-template-id is always replaced with a template-id
1280/// annotation token.
1281///
1282/// \param TypeConstraint if true, then this is actually a type-constraint,
1283/// meaning that the template argument list can be omitted (and the template in
1284/// question must be a concept).
1285///
1286/// If an unrecoverable parse error occurs and no annotation token can be
1287/// formed, this function returns true.
1288///
1289bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
                                   CXXScopeSpec &SS,
                                   SourceLocation TemplateKWLoc,
                                   UnqualifiedId &TemplateName,
                                   bool AllowTypeAnnotation,
                                   bool TypeConstraint) {
assert(getLangOpts().CPlusPlus && "Can only annotate template-ids in C++")((void)0);
assert((Tok.is(tok::less) || TypeConstraint) &&((void)0)
       "Parser isn't at the beginning of a template-id")((void)0);
assert(!(TypeConstraint && AllowTypeAnnotation) && "type-constraint can't be "((void)0)
                                                   "a type annotation")((void)0);
assert((!TypeConstraint || TNK == TNK_Concept_template) && "type-constraint "((void)0)
       "must accompany a concept name")((void)0);
assert((Template || TNK == TNK_Non_template) && "missing template name")((void)0);

// Consume the template-name.
SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();

// Parse the enclosed template argument list.
SourceLocation LAngleLoc, RAngleLoc;
TemplateArgList TemplateArgs;
bool ArgsInvalid = false;
if (!TypeConstraint || Tok.is(tok::less)) {
  ArgsInvalid = ParseTemplateIdAfterTemplateName(false, LAngleLoc,
                                                 TemplateArgs, RAngleLoc);
  // If we couldn't recover from invalid arguments, don't form an annotation
  // token -- we don't know how much to annotate.
  // FIXME: This can lead to duplicate diagnostics if we retry parsing this
  // template-id in another context. Try to annotate anyway?
  if (RAngleLoc.isInvalid())
    return true;
}

ASTTemplateArgsPtr TemplateArgsPtr(TemplateArgs);

// Build the annotation token.
if (TNK == TNK_Type_template && AllowTypeAnnotation) {
  TypeResult Type = ArgsInvalid
                        ? TypeError()
                        : Actions.ActOnTemplateIdType(
                              getCurScope(), SS, TemplateKWLoc, Template,
                              TemplateName.Identifier, TemplateNameLoc,
                              LAngleLoc, TemplateArgsPtr, RAngleLoc);

  Tok.setKind(tok::annot_typename);
  setTypeAnnotation(Tok, Type);
  if (SS.isNotEmpty())
    Tok.setLocation(SS.getBeginLoc());
  else if (TemplateKWLoc.isValid())
    Tok.setLocation(TemplateKWLoc);
  else
    Tok.setLocation(TemplateNameLoc);
} else {
  // Build a template-id annotation token that can be processed
  // later.
  Tok.setKind(tok::annot_template_id);

  IdentifierInfo *TemplateII =
      TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
          ? TemplateName.Identifier
          : nullptr;

  OverloadedOperatorKind OpKind =
      TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
          ? OO_None
          : TemplateName.OperatorFunctionId.Operator;

  TemplateIdAnnotation *TemplateId = TemplateIdAnnotation::Create(
      TemplateKWLoc, TemplateNameLoc, TemplateII, OpKind, Template, TNK,
      LAngleLoc, RAngleLoc, TemplateArgs, ArgsInvalid, TemplateIds);

  Tok.setAnnotationValue(TemplateId);
  if (TemplateKWLoc.isValid())
    Tok.setLocation(TemplateKWLoc);
  else
    Tok.setLocation(TemplateNameLoc);
}

// Common fields for the annotation token
Tok.setAnnotationEndLoc(RAngleLoc);

// In case the tokens were cached, have Preprocessor replace them with the
// annotation token.
PP.AnnotateCachedTokens(Tok);
return false;
1374}

1376/// Replaces a template-id annotation token with a type
1377/// annotation token.
1378///
1379/// If there was a failure when forming the type from the template-id,
1380/// a type annotation token will still be created, but will have a
1381/// NULL type pointer to signify an error.
1382///
1383/// \param SS The scope specifier appearing before the template-id, if any.
1384///
1385/// \param IsClassName Is this template-id appearing in a context where we
1386/// know it names a class, such as in an elaborated-type-specifier or
1387/// base-specifier? ('typename' and 'template' are unneeded and disallowed
1388/// in those contexts.)
1389void Parser::AnnotateTemplateIdTokenAsType(CXXScopeSpec &SS,
                                         bool IsClassName) {
assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens")((void)0);

TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
assert(TemplateId->mightBeType() &&((void)0)
       "Only works for type and dependent templates")((void)0);

ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
                                   TemplateId->NumArgs);

TypeResult Type =
    TemplateId->isInvalid()
        ? TypeError()
        : Actions.ActOnTemplateIdType(
              getCurScope(), SS, TemplateId->TemplateKWLoc,
              TemplateId->Template, TemplateId->Name,
              TemplateId->TemplateNameLoc, TemplateId->LAngleLoc,
              TemplateArgsPtr, TemplateId->RAngleLoc,
              /*IsCtorOrDtorName*/ false, IsClassName);
// Create the new "type" annotation token.
Tok.setKind(tok::annot_typename);
setTypeAnnotation(Tok, Type);
if (SS.isNotEmpty()) // it was a C++ qualified type name.
  Tok.setLocation(SS.getBeginLoc());
// End location stays the same

// Replace the template-id annotation token, and possible the scope-specifier
// that precedes it, with the typename annotation token.
PP.AnnotateCachedTokens(Tok);
1419}

1421/// Determine whether the given token can end a template argument.
1422static bool isEndOfTemplateArgument(Token Tok) {
// FIXME: Handle '>>>'.
return Tok.isOneOf(tok::comma, tok::greater, tok::greatergreater,
                   tok::greatergreatergreater);
1426}

1428/// Parse a C++ template template argument.
1429ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
    !Tok.is(tok::annot_cxxscope))
  return ParsedTemplateArgument();

// C++0x [temp.arg.template]p1:
//   A template-argument for a template template-parameter shall be the name
//   of a class template or an alias template, expressed as id-expression.
//
// We parse an id-expression that refers to a class template or alias
// template. The grammar we parse is:
//
//   nested-name-specifier[opt] template[opt] identifier ...[opt]
//
// followed by a token that terminates a template argument, such as ',',
// '>', or (in some cases) '>>'.
CXXScopeSpec SS; // nested-name-specifier, if present
ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
                               /*ObjectHadErrors=*/false,
                               /*EnteringContext=*/false);

ParsedTemplateArgument Result;
SourceLocation EllipsisLoc;
if (SS.isSet() && Tok.is(tok::kw_template)) {
  // Parse the optional 'template' keyword following the
  // nested-name-specifier.
  SourceLocation TemplateKWLoc = ConsumeToken();

  if (Tok.is(tok::identifier)) {
    // We appear to have a dependent template name.
    UnqualifiedId Name;
    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
    ConsumeToken(); // the identifier

    TryConsumeToken(tok::ellipsis, EllipsisLoc);

    // If the next token signals the end of a template argument, then we have
    // a (possibly-dependent) template name that could be a template template
    // argument.
    TemplateTy Template;
    if (isEndOfTemplateArgument(Tok) &&
        Actions.ActOnTemplateName(getCurScope(), SS, TemplateKWLoc, Name,
                                  /*ObjectType=*/nullptr,
                                  /*EnteringContext=*/false, Template))
      Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
  }
} else if (Tok.is(tok::identifier)) {
  // We may have a (non-dependent) template name.
  TemplateTy Template;
  UnqualifiedId Name;
  Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
  ConsumeToken(); // the identifier

  TryConsumeToken(tok::ellipsis, EllipsisLoc);

  if (isEndOfTemplateArgument(Tok)) {
    bool MemberOfUnknownSpecialization;
    TemplateNameKind TNK = Actions.isTemplateName(
        getCurScope(), SS,
        /*hasTemplateKeyword=*/false, Name,
        /*ObjectType=*/nullptr,
        /*EnteringContext=*/false, Template, MemberOfUnknownSpecialization);
    if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
      // We have an id-expression that refers to a class template or
      // (C++0x) alias template.
      Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
    }
  }
}

// If this is a pack expansion, build it as such.
if (EllipsisLoc.isValid() && !Result.isInvalid())
  Result = Actions.ActOnPackExpansion(Result, EllipsisLoc);

return Result;
1504}

1506/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
1507///
1508///       template-argument: [C++ 14.2]
1509///         constant-expression
1510///         type-id
1511///         id-expression
1512ParsedTemplateArgument Parser::ParseTemplateArgument() {
// C++ [temp.arg]p2:
//   In a template-argument, an ambiguity between a type-id and an
//   expression is resolved to a type-id, regardless of the form of
//   the corresponding template-parameter.
//
// Therefore, we initially try to parse a type-id - and isCXXTypeId might look
// up and annotate an identifier as an id-expression during disambiguation,
// so enter the appropriate context for a constant expression template
// argument before trying to disambiguate.

EnterExpressionEvaluationContext EnterConstantEvaluated(
  Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated,
  /*LambdaContextDecl=*/nullptr,
  /*ExprContext=*/Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
if (isCXXTypeId(TypeIdAsTemplateArgument)) {
  TypeResult TypeArg = ParseTypeName(
      /*Range=*/nullptr, DeclaratorContext::TemplateArg);
  return Actions.ActOnTemplateTypeArgument(TypeArg);
}

// Try to parse a template template argument.
{
  TentativeParsingAction TPA(*this);

  ParsedTemplateArgument TemplateTemplateArgument
    = ParseTemplateTemplateArgument();
  if (!TemplateTemplateArgument.isInvalid()) {
    TPA.Commit();
    return TemplateTemplateArgument;
  }

  // Revert this tentative parse to parse a non-type template argument.
  TPA.Revert();
}

// Parse a non-type template argument.
SourceLocation Loc = Tok.getLocation();
ExprResult ExprArg = ParseConstantExpressionInExprEvalContext(MaybeTypeCast);
if (ExprArg.isInvalid() || !ExprArg.get()) {
  return ParsedTemplateArgument();
}

return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
                              ExprArg.get(), Loc);
1557}

1559/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1560/// (C++ [temp.names]). Returns true if there was an error.
1561///
1562///       template-argument-list: [C++ 14.2]
1563///         template-argument
1564///         template-argument-list ',' template-argument
1565bool
1566Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {

ColonProtectionRAIIObject ColonProtection(*this, false);

do {
  ParsedTemplateArgument Arg = ParseTemplateArgument();
  SourceLocation EllipsisLoc;
  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
    Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);

  if (Arg.isInvalid())
    return true;

  // Save this template argument.
  TemplateArgs.push_back(Arg);

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

return false;
1587}

1589/// Parse a C++ explicit template instantiation
1590/// (C++ [temp.explicit]).
1591///
1592///       explicit-instantiation:
1593///         'extern' [opt] 'template' declaration
1594///
1595/// Note that the 'extern' is a GNU extension and C++11 feature.
1596Decl *Parser::ParseExplicitInstantiation(DeclaratorContext Context,
                                       SourceLocation ExternLoc,
                                       SourceLocation TemplateLoc,
                                       SourceLocation &DeclEnd,
                                       ParsedAttributes &AccessAttrs,
                                       AccessSpecifier AS) {
// This isn't really required here.
ParsingDeclRAIIObject
  ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);

return ParseSingleDeclarationAfterTemplate(
    Context, ParsedTemplateInfo(ExternLoc, TemplateLoc),
    ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
1609}

1611SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
if (TemplateParams)
  return getTemplateParamsRange(TemplateParams->data(),
                                TemplateParams->size());

SourceRange R(TemplateLoc);
if (ExternLoc.isValid())
  R.setBegin(ExternLoc);
return R;
1620}

1622void Parser::LateTemplateParserCallback(void *P, LateParsedTemplate &LPT) {
((Parser *)P)->ParseLateTemplatedFuncDef(LPT);
1
Calling 'Parser::ParseLateTemplatedFuncDef'→
1624}

1626/// Late parse a C++ function template in Microsoft mode.
1627void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
if (!LPT.D)
2
←
Assuming field 'D' is non-null→
3
←
Taking false branch→
   return;

// Destroy TemplateIdAnnotations when we're done, if possible.
DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(*this);

// Get the FunctionDecl.
FunctionDecl *FunD = LPT.D->getAsFunction();
4
←
'FunD' initialized here→
// Track template parameter depth.
TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);

// To restore the context after late parsing.
Sema::ContextRAII GlobalSavedContext(
    Actions, Actions.Context.getTranslationUnitDecl());

MultiParseScope Scopes(*this);

// Get the list of DeclContexts to reenter.
SmallVector<DeclContext*, 4> DeclContextsToReenter;
for (DeclContext *DC = FunD; DC && !DC->isTranslationUnit();
5
←
Assuming 'DC' is null→
6
←
Assuming pointer value is null→
     DC = DC->getLexicalParent())
  DeclContextsToReenter.push_back(DC);

// Reenter scopes from outermost to innermost.
for (DeclContext *DC : reverse(DeclContextsToReenter)) {
  CurTemplateDepthTracker.addDepth(
      ReenterTemplateScopes(Scopes, cast<Decl>(DC)));
7
←
'DC' is a 'Decl'→
  Scopes.Enter(Scope::DeclScope);
  // We'll reenter the function context itself below.
  if (DC7.1
'DC' is not equal to 'FunD'
 != FunD)
8
←
Taking true branch→
    Actions.PushDeclContext(Actions.getCurScope(), DC);
}

assert(!LPT.Toks.empty() && "Empty body!")((void)0);

// Append the current token at the end of the new token stream so that it
// doesn't get lost.
LPT.Toks.push_back(Tok);
PP.EnterTokenStream(LPT.Toks, true, /*IsReinject*/true);

// Consume the previously pushed token.
ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try) &&((void)0)
       "Inline method not starting with '{', ':' or 'try'")((void)0);

// 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);

// Recreate the containing function DeclContext.
Sema::ContextRAII FunctionSavedContext(Actions, FunD->getLexicalParent());
9
←
Called C++ object pointer is null

Actions.ActOnStartOfFunctionDef(getCurScope(), FunD);

if (Tok.is(tok::kw_try)) {
  ParseFunctionTryBlock(LPT.D, FnScope);
} else {
  if (Tok.is(tok::colon))
    ParseConstructorInitializer(LPT.D);
  else
    Actions.ActOnDefaultCtorInitializers(LPT.D);

  if (Tok.is(tok::l_brace)) {
    assert((!isa<FunctionTemplateDecl>(LPT.D) ||((void)0)
            cast<FunctionTemplateDecl>(LPT.D)((void)0)
                    ->getTemplateParameters()((void)0)
                    ->getDepth() == TemplateParameterDepth - 1) &&((void)0)
           "TemplateParameterDepth should be greater than the depth of "((void)0)
           "current template being instantiated!")((void)0);
    ParseFunctionStatementBody(LPT.D, FnScope);
    Actions.UnmarkAsLateParsedTemplate(FunD);
  } else
    Actions.ActOnFinishFunctionBody(LPT.D, nullptr);
}
1703}

1705/// Lex a delayed template function for late parsing.
1706void Parser::LexTemplateFunctionForLateParsing(CachedTokens &Toks) {
tok::TokenKind kind = Tok.getKind();
if (!ConsumeAndStoreFunctionPrologue(Toks)) {
  // 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);
  }
}
1720}

1722/// We've parsed something that could plausibly be intended to be a template
1723/// name (\p LHS) followed by a '<' token, and the following code can't possibly
1724/// be an expression. Determine if this is likely to be a template-id and if so,
1725/// diagnose it.
1726bool Parser::diagnoseUnknownTemplateId(ExprResult LHS, SourceLocation Less) {
TentativeParsingAction TPA(*this);
// FIXME: We could look at the token sequence in a lot more detail here.
if (SkipUntil(tok::greater, tok::greatergreater, tok::greatergreatergreater,
              StopAtSemi | StopBeforeMatch)) {
  TPA.Commit();

  SourceLocation Greater;
  ParseGreaterThanInTemplateList(Less, Greater, true, false);
  Actions.diagnoseExprIntendedAsTemplateName(getCurScope(), LHS,
                                             Less, Greater);
  return true;
}

// There's no matching '>' token, this probably isn't supposed to be
// interpreted as a template-id. Parse it as an (ill-formed) comparison.
TPA.Revert();
return false;
1744}

1746void Parser::checkPotentialAngleBracket(ExprResult &PotentialTemplateName) {
assert(Tok.is(tok::less) && "not at a potential angle bracket")((void)0);

bool DependentTemplateName = false;
if (!Actions.mightBeIntendedToBeTemplateName(PotentialTemplateName,
                                             DependentTemplateName))
  return;

// OK, this might be a name that the user intended to be parsed as a
// template-name, followed by a '<' token. Check for some easy cases.

// If we have potential_template<>, then it's supposed to be a template-name.
if (NextToken().is(tok::greater) ||
    (getLangOpts().CPlusPlus11 &&
     NextToken().isOneOf(tok::greatergreater, tok::greatergreatergreater))) {
  SourceLocation Less = ConsumeToken();
  SourceLocation Greater;
  ParseGreaterThanInTemplateList(Less, Greater, true, false);
  Actions.diagnoseExprIntendedAsTemplateName(
      getCurScope(), PotentialTemplateName, Less, Greater);
  // FIXME: Perform error recovery.
  PotentialTemplateName = ExprError();
  return;
}

// If we have 'potential_template<type-id', assume it's supposed to be a
// template-name if there's a matching '>' later on.
{
  // FIXME: Avoid the tentative parse when NextToken() can't begin a type.
  TentativeParsingAction TPA(*this);
  SourceLocation Less = ConsumeToken();
  if (isTypeIdUnambiguously() &&
      diagnoseUnknownTemplateId(PotentialTemplateName, Less)) {
    TPA.Commit();
    // FIXME: Perform error recovery.
    PotentialTemplateName = ExprError();
    return;
  }
  TPA.Revert();
}

// Otherwise, remember that we saw this in case we see a potentially-matching
// '>' token later on.
AngleBracketTracker::Priority Priority =
    (DependentTemplateName ? AngleBracketTracker::DependentName
                           : AngleBracketTracker::PotentialTypo) |
    (Tok.hasLeadingSpace() ? AngleBracketTracker::SpaceBeforeLess
                           : AngleBracketTracker::NoSpaceBeforeLess);
AngleBrackets.add(*this, PotentialTemplateName.get(), Tok.getLocation(),
                  Priority);
1796}

1798bool Parser::checkPotentialAngleBracketDelimiter(
  const AngleBracketTracker::Loc &LAngle, const Token &OpToken) {
// If a comma in an expression context is followed by a type that can be a
// template argument and cannot be an expression, then this is ill-formed,
// but might be intended to be part of a template-id.
if (OpToken.is(tok::comma) && isTypeIdUnambiguously() &&
    diagnoseUnknownTemplateId(LAngle.TemplateName, LAngle.LessLoc)) {
  AngleBrackets.clear(*this);
  return true;
}

// If a context that looks like a template-id is followed by '()', then
// this is ill-formed, but might be intended to be a template-id
// followed by '()'.
if (OpToken.is(tok::greater) && Tok.is(tok::l_paren) &&
    NextToken().is(tok::r_paren)) {
  Actions.diagnoseExprIntendedAsTemplateName(
      getCurScope(), LAngle.TemplateName, LAngle.LessLoc,
      OpToken.getLocation());
  AngleBrackets.clear(*this);
  return true;
}

// After a '>' (etc), we're no longer potentially in a construct that's
// intended to be treated as a template-id.
if (OpToken.is(tok::greater) ||
    (getLangOpts().CPlusPlus11 &&
     OpToken.isOneOf(tok::greatergreater, tok::greatergreatergreater)))
  AngleBrackets.clear(*this);
return false;
1828}