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//===----------------------------------------------------------------------===//
12
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;
24
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) {
29  return Actions.ActOnReenterTemplateScope(D, [&] {
30    S.Enter(Scope::TemplateParamScope);
31    return Actions.getCurScope();
32  });
33}
34
35/// Parse a template declaration, explicit instantiation, or
36/// explicit specialization.
37Decl *Parser::ParseDeclarationStartingWithTemplate(
38    DeclaratorContext Context, SourceLocation &DeclEnd,
39    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
40  ObjCDeclContextSwitch ObjCDC(*this);
41
42  if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less)) {
43    return ParseExplicitInstantiation(Context, SourceLocation(), ConsumeToken(),
44                                      DeclEnd, AccessAttrs, AS);
45  }
46  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AccessAttrs,
47                                                  AS);
48}
49
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(
75    DeclaratorContext Context, SourceLocation &DeclEnd,
76    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
77  assert(Tok.isOneOf(tok::kw_export, tok::kw_template) &&
78         "Token does not start a template declaration.");
79
80  MultiParseScope TemplateParamScopes(*this);
81
82  // Tell the action that names should be checked in the context of
83  // the declaration to come.
84  ParsingDeclRAIIObject
85    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
86
87  // Parse multiple levels of template headers within this template
88  // parameter scope, e.g.,
89  //
90  //   template<typename T>
91  //     template<typename U>
92  //       class A<T>::B { ... };
93  //
94  // We parse multiple levels non-recursively so that we can build a
95  // single data structure containing all of the template parameter
96  // lists to easily differentiate between the case above and:
97  //
98  //   template<typename T>
99  //   class A {
100  //     template<typename U> class B;
101  //   };
102  //
103  // In the first case, the action for declaring A<T>::B receives
104  // both template parameter lists. In the second case, the action for
105  // defining A<T>::B receives just the inner template parameter list
106  // (and retrieves the outer template parameter list from its
107  // context).
108  bool isSpecialization = true;
109  bool LastParamListWasEmpty = false;
110  TemplateParameterLists ParamLists;
111  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
112
113  do {
114    // Consume the 'export', if any.
115    SourceLocation ExportLoc;
116    TryConsumeToken(tok::kw_export, ExportLoc);
117
118    // Consume the 'template', which should be here.
119    SourceLocation TemplateLoc;
120    if (!TryConsumeToken(tok::kw_template, TemplateLoc)) {
121      Diag(Tok.getLocation(), diag::err_expected_template);
122      return nullptr;
123    }
124
125    // Parse the '<' template-parameter-list '>'
126    SourceLocation LAngleLoc, RAngleLoc;
127    SmallVector<NamedDecl*, 4> TemplateParams;
128    if (ParseTemplateParameters(TemplateParamScopes,
129                                CurTemplateDepthTracker.getDepth(),
130                                TemplateParams, LAngleLoc, RAngleLoc)) {
131      // Skip until the semi-colon or a '}'.
132      SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
133      TryConsumeToken(tok::semi);
134      return nullptr;
135    }
136
137    ExprResult OptionalRequiresClauseConstraintER;
138    if (!TemplateParams.empty()) {
139      isSpecialization = false;
140      ++CurTemplateDepthTracker;
141
142      if (TryConsumeToken(tok::kw_requires)) {
143        OptionalRequiresClauseConstraintER =
144            Actions.CorrectDelayedTyposInExpr(
145                ParseConstraintLogicalOrExpression(
146                    /*IsTrailingRequiresClause=*/false));
147        if (!OptionalRequiresClauseConstraintER.isUsable()) {
148          // Skip until the semi-colon or a '}'.
149          SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
150          TryConsumeToken(tok::semi);
151          return nullptr;
152        }
153      }
154    } else {
155      LastParamListWasEmpty = true;
156    }
157
158    ParamLists.push_back(Actions.ActOnTemplateParameterList(
159        CurTemplateDepthTracker.getDepth(), ExportLoc, TemplateLoc, LAngleLoc,
160        TemplateParams, RAngleLoc, OptionalRequiresClauseConstraintER.get()));
161  } while (Tok.isOneOf(tok::kw_export, tok::kw_template));
162
163  // Parse the actual template declaration.
164  if (Tok.is(tok::kw_concept))
165    return ParseConceptDefinition(
166        ParsedTemplateInfo(&ParamLists, isSpecialization,
167                           LastParamListWasEmpty),
168        DeclEnd);
169
170  return ParseSingleDeclarationAfterTemplate(
171      Context,
172      ParsedTemplateInfo(&ParamLists, isSpecialization, LastParamListWasEmpty),
173      ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
174}
175
176/// Parse a single declaration that declares a template,
177/// template specialization, or explicit instantiation of a template.
178///
179/// \param DeclEnd will receive the source location of the last token
180/// within this declaration.
181///
182/// \param AS the access specifier associated with this
183/// declaration. Will be AS_none for namespace-scope declarations.
184///
185/// \returns the new declaration.
186Decl *Parser::ParseSingleDeclarationAfterTemplate(
187    DeclaratorContext Context, const ParsedTemplateInfo &TemplateInfo,
188    ParsingDeclRAIIObject &DiagsFromTParams, SourceLocation &DeclEnd,
189    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
190  assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
191         "Template information required");
192
193  if (Tok.is(tok::kw_static_assert)) {
194    // A static_assert declaration may not be templated.
195    Diag(Tok.getLocation(), diag::err_templated_invalid_declaration)
196      << TemplateInfo.getSourceRange();
197    // Parse the static_assert declaration to improve error recovery.
198    return ParseStaticAssertDeclaration(DeclEnd);
199  }
200
201  if (Context == DeclaratorContext::MemberContext) {
202    // We are parsing a member template.
203    ParseCXXClassMemberDeclaration(AS, AccessAttrs, TemplateInfo,
204                                   &DiagsFromTParams);
205    return nullptr;
206  }
207
208  ParsedAttributesWithRange prefixAttrs(AttrFactory);
209  MaybeParseCXX11Attributes(prefixAttrs);
210
211  if (Tok.is(tok::kw_using)) {
212    auto usingDeclPtr = ParseUsingDirectiveOrDeclaration(Context, TemplateInfo, DeclEnd,
213                                                         prefixAttrs);
214    if (!usingDeclPtr || !usingDeclPtr.get().isSingleDecl())
215      return nullptr;
216    return usingDeclPtr.get().getSingleDecl();
217  }
218
219  // Parse the declaration specifiers, stealing any diagnostics from
220  // the template parameters.
221  ParsingDeclSpec DS(*this, &DiagsFromTParams);
222
223  ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
224                             getDeclSpecContextFromDeclaratorContext(Context));
225
226  if (Tok.is(tok::semi)) {
227    ProhibitAttributes(prefixAttrs);
228    DeclEnd = ConsumeToken();
229    RecordDecl *AnonRecord = nullptr;
230    Decl *Decl = Actions.ParsedFreeStandingDeclSpec(
231        getCurScope(), AS, DS,
232        TemplateInfo.TemplateParams ? *TemplateInfo.TemplateParams
233                                    : MultiTemplateParamsArg(),
234        TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation,
235        AnonRecord);
236    assert(!AnonRecord &&
237           "Anonymous unions/structs should not be valid with template");
238    DS.complete(Decl);
239    return Decl;
240  }
241
242  // Move the attributes from the prefix into the DS.
243  if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation)
244    ProhibitAttributes(prefixAttrs);
245  else
246    DS.takeAttributesFrom(prefixAttrs);
247
248  // Parse the declarator.
249  ParsingDeclarator DeclaratorInfo(*this, DS, (DeclaratorContext)Context);
250  if (TemplateInfo.TemplateParams)
251    DeclaratorInfo.setTemplateParameterLists(*TemplateInfo.TemplateParams);
252  ParseDeclarator(DeclaratorInfo);
253  // Error parsing the declarator?
254  if (!DeclaratorInfo.hasName()) {
255    // If so, skip until the semi-colon or a }.
256    SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
257    if (Tok.is(tok::semi))
258      ConsumeToken();
259    return nullptr;
260  }
261
262  llvm::TimeTraceScope TimeScope("ParseTemplate", [&]() {
263    return std::string(DeclaratorInfo.getIdentifier() != nullptr
264                           ? DeclaratorInfo.getIdentifier()->getName()
265                           : "<unknown>");
266  });
267
268  LateParsedAttrList LateParsedAttrs(true);
269  if (DeclaratorInfo.isFunctionDeclarator()) {
270    if (Tok.is(tok::kw_requires))
271      ParseTrailingRequiresClause(DeclaratorInfo);
272
273    MaybeParseGNUAttributes(DeclaratorInfo, &LateParsedAttrs);
274  }
275
276  if (DeclaratorInfo.isFunctionDeclarator() &&
277      isStartOfFunctionDefinition(DeclaratorInfo)) {
278
279    // Function definitions are only allowed at file scope and in C++ classes.
280    // The C++ inline method definition case is handled elsewhere, so we only
281    // need to handle the file scope definition case.
282    if (Context != DeclaratorContext::FileContext) {
283      Diag(Tok, diag::err_function_definition_not_allowed);
284      SkipMalformedDecl();
285      return nullptr;
286    }
287
288    if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
289      // Recover by ignoring the 'typedef'. This was probably supposed to be
290      // the 'typename' keyword, which we should have already suggested adding
291      // if it's appropriate.
292      Diag(DS.getStorageClassSpecLoc(), diag::err_function_declared_typedef)
293        << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
294      DS.ClearStorageClassSpecs();
295    }
296
297    if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
298      if (DeclaratorInfo.getName().getKind() !=
299          UnqualifiedIdKind::IK_TemplateId) {
300        // If the declarator-id is not a template-id, issue a diagnostic and
301        // recover by ignoring the 'template' keyword.
302        Diag(Tok, diag::err_template_defn_explicit_instantiation) << 0;
303        return ParseFunctionDefinition(DeclaratorInfo, ParsedTemplateInfo(),
304                                       &LateParsedAttrs);
305      } else {
306        SourceLocation LAngleLoc
307          = PP.getLocForEndOfToken(TemplateInfo.TemplateLoc);
308        Diag(DeclaratorInfo.getIdentifierLoc(),
309             diag::err_explicit_instantiation_with_definition)
310            << SourceRange(TemplateInfo.TemplateLoc)
311            << FixItHint::CreateInsertion(LAngleLoc, "<>");
312
313        // Recover as if it were an explicit specialization.
314        TemplateParameterLists FakedParamLists;
315        FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
316            0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, None,
317            LAngleLoc, nullptr));
318
319        return ParseFunctionDefinition(
320            DeclaratorInfo, ParsedTemplateInfo(&FakedParamLists,
321                                               /*isSpecialization=*/true,
322                                               /*lastParameterListWasEmpty=*/true),
323            &LateParsedAttrs);
324      }
325    }
326    return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo,
327                                   &LateParsedAttrs);
328  }
329
330  // Parse this declaration.
331  Decl *ThisDecl = ParseDeclarationAfterDeclarator(DeclaratorInfo,
332                                                   TemplateInfo);
333
334  if (Tok.is(tok::comma)) {
335    Diag(Tok, diag::err_multiple_template_declarators)
336      << (int)TemplateInfo.Kind;
337    SkipUntil(tok::semi);
338    return ThisDecl;
339  }
340
341  // Eat the semi colon after the declaration.
342  ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
343  if (LateParsedAttrs.size() > 0)
344    ParseLexedAttributeList(LateParsedAttrs, ThisDecl, true, false);
345  DeclaratorInfo.complete(ThisDecl);
346  return ThisDecl;
347}
348
349/// \brief Parse a single declaration that declares a concept.
350///
351/// \param DeclEnd will receive the source location of the last token
352/// within this declaration.
353///
354/// \returns the new declaration.
355Decl *
356Parser::ParseConceptDefinition(const ParsedTemplateInfo &TemplateInfo,
357                               SourceLocation &DeclEnd) {
358  assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
359         "Template information required");
360  assert(Tok.is(tok::kw_concept) &&
361         "ParseConceptDefinition must be called when at a 'concept' keyword");
362
363  ConsumeToken(); // Consume 'concept'
364
365  SourceLocation BoolKWLoc;
366  if (TryConsumeToken(tok::kw_bool, BoolKWLoc))
367    Diag(Tok.getLocation(), diag::ext_concept_legacy_bool_keyword) <<
368        FixItHint::CreateRemoval(SourceLocation(BoolKWLoc));
369
370  DiagnoseAndSkipCXX11Attributes();
371
372  CXXScopeSpec SS;
373  if (ParseOptionalCXXScopeSpecifier(
374          SS, /*ObjectType=*/nullptr,
375          /*ObjectHadErrors=*/false, /*EnteringContext=*/false,
376          /*MayBePseudoDestructor=*/nullptr,
377          /*IsTypename=*/false, /*LastII=*/nullptr, /*OnlyNamespace=*/true) ||
378      SS.isInvalid()) {
379    SkipUntil(tok::semi);
380    return nullptr;
381  }
382
383  if (SS.isNotEmpty())
384    Diag(SS.getBeginLoc(),
385         diag::err_concept_definition_not_identifier);
386
387  UnqualifiedId Result;
388  if (ParseUnqualifiedId(SS, /*ObjectType=*/nullptr,
389                         /*ObjectHadErrors=*/false, /*EnteringContext=*/false,
390                         /*AllowDestructorName=*/false,
391                         /*AllowConstructorName=*/false,
392                         /*AllowDeductionGuide=*/false,
393                         /*TemplateKWLoc=*/nullptr, Result)) {
394    SkipUntil(tok::semi);
395    return nullptr;
396  }
397
398  if (Result.getKind() != UnqualifiedIdKind::IK_Identifier) {
399    Diag(Result.getBeginLoc(), diag::err_concept_definition_not_identifier);
400    SkipUntil(tok::semi);
401    return nullptr;
402  }
403
404  IdentifierInfo *Id = Result.Identifier;
405  SourceLocation IdLoc = Result.getBeginLoc();
406
407  DiagnoseAndSkipCXX11Attributes();
408
409  if (!TryConsumeToken(tok::equal)) {
410    Diag(Tok.getLocation(), diag::err_expected) << tok::equal;
411    SkipUntil(tok::semi);
412    return nullptr;
413  }
414
415  ExprResult ConstraintExprResult =
416      Actions.CorrectDelayedTyposInExpr(ParseConstraintExpression());
417  if (ConstraintExprResult.isInvalid()) {
418    SkipUntil(tok::semi);
419    return nullptr;
420  }
421
422  DeclEnd = Tok.getLocation();
423  ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
424  Expr *ConstraintExpr = ConstraintExprResult.get();
425  return Actions.ActOnConceptDefinition(getCurScope(),
426                                        *TemplateInfo.TemplateParams,
427                                        Id, IdLoc, ConstraintExpr);
428}
429
430/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
431/// angle brackets. Depth is the depth of this template-parameter-list, which
432/// is the number of template headers directly enclosing this template header.
433/// TemplateParams is the current list of template parameters we're building.
434/// The template parameter we parse will be added to this list. LAngleLoc and
435/// RAngleLoc will receive the positions of the '<' and '>', respectively,
436/// that enclose this template parameter list.
437///
438/// \returns true if an error occurred, false otherwise.
439bool Parser::ParseTemplateParameters(
440    MultiParseScope &TemplateScopes, unsigned Depth,
441    SmallVectorImpl<NamedDecl *> &TemplateParams, SourceLocation &LAngleLoc,
442    SourceLocation &RAngleLoc) {
443  // Get the template parameter list.
444  if (!TryConsumeToken(tok::less, LAngleLoc)) {
445    Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
446    return true;
447  }
448
449  // Try to parse the template parameter list.
450  bool Failed = false;
451  // FIXME: Missing greatergreatergreater support.
452  if (!Tok.is(tok::greater) && !Tok.is(tok::greatergreater)) {
453    TemplateScopes.Enter(Scope::TemplateParamScope);
454    Failed = ParseTemplateParameterList(Depth, TemplateParams);
455  }
456
457  if (Tok.is(tok::greatergreater)) {
458    // No diagnostic required here: a template-parameter-list can only be
459    // followed by a declaration or, for a template template parameter, the
460    // 'class' keyword. Therefore, the second '>' will be diagnosed later.
461    // This matters for elegant diagnosis of:
462    //   template<template<typename>> struct S;
463    Tok.setKind(tok::greater);
464    RAngleLoc = Tok.getLocation();
465    Tok.setLocation(Tok.getLocation().getLocWithOffset(1));
466  } else if (!TryConsumeToken(tok::greater, RAngleLoc) && Failed) {
467    Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
468    return true;
469  }
470  return false;
471}
472
473/// ParseTemplateParameterList - Parse a template parameter list. If
474/// the parsing fails badly (i.e., closing bracket was left out), this
475/// will try to put the token stream in a reasonable position (closing
476/// a statement, etc.) and return false.
477///
478///       template-parameter-list:    [C++ temp]
479///         template-parameter
480///         template-parameter-list ',' template-parameter
481bool
482Parser::ParseTemplateParameterList(const unsigned Depth,
483                             SmallVectorImpl<NamedDecl*> &TemplateParams) {
484  while (1) {
485
486    if (NamedDecl *TmpParam
487          = ParseTemplateParameter(Depth, TemplateParams.size())) {
488      TemplateParams.push_back(TmpParam);
489    } else {
490      // If we failed to parse a template parameter, skip until we find
491      // a comma or closing brace.
492      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
493                StopAtSemi | StopBeforeMatch);
494    }
495
496    // Did we find a comma or the end of the template parameter list?
497    if (Tok.is(tok::comma)) {
498      ConsumeToken();
499    } else if (Tok.isOneOf(tok::greater, tok::greatergreater)) {
500      // Don't consume this... that's done by template parser.
501      break;
502    } else {
503      // Somebody probably forgot to close the template. Skip ahead and
504      // try to get out of the expression. This error is currently
505      // subsumed by whatever goes on in ParseTemplateParameter.
506      Diag(Tok.getLocation(), diag::err_expected_comma_greater);
507      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
508                StopAtSemi | StopBeforeMatch);
509      return false;
510    }
511  }
512  return true;
513}
514
515/// Determine whether the parser is at the start of a template
516/// type parameter.
517Parser::TPResult Parser::isStartOfTemplateTypeParameter() {
518  if (Tok.is(tok::kw_class)) {
519    // "class" may be the start of an elaborated-type-specifier or a
520    // type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
521    switch (NextToken().getKind()) {
522    case tok::equal:
523    case tok::comma:
524    case tok::greater:
525    case tok::greatergreater:
526    case tok::ellipsis:
527      return TPResult::True;
528
529    case tok::identifier:
530      // This may be either a type-parameter or an elaborated-type-specifier.
531      // We have to look further.
532      break;
533
534    default:
535      return TPResult::False;
536    }
537
538    switch (GetLookAheadToken(2).getKind()) {
539    case tok::equal:
540    case tok::comma:
541    case tok::greater:
542    case tok::greatergreater:
543      return TPResult::True;
544
545    default:
546      return TPResult::False;
547    }
548  }
549
550  if (TryAnnotateTypeConstraint())
551    return TPResult::Error;
552
553  if (isTypeConstraintAnnotation() &&
554      // Next token might be 'auto' or 'decltype', indicating that this
555      // type-constraint is in fact part of a placeholder-type-specifier of a
556      // non-type template parameter.
557      !GetLookAheadToken(Tok.is(tok::annot_cxxscope) ? 2 : 1)
558           .isOneOf(tok::kw_auto, tok::kw_decltype))
559    return TPResult::True;
560
561  // 'typedef' is a reasonably-common typo/thinko for 'typename', and is
562  // ill-formed otherwise.
563  if (Tok.isNot(tok::kw_typename) && Tok.isNot(tok::kw_typedef))
564    return TPResult::False;
565
566  // C++ [temp.param]p2:
567  //   There is no semantic difference between class and typename in a
568  //   template-parameter. typename followed by an unqualified-id
569  //   names a template type parameter. typename followed by a
570  //   qualified-id denotes the type in a non-type
571  //   parameter-declaration.
572  Token Next = NextToken();
573
574  // If we have an identifier, skip over it.
575  if (Next.getKind() == tok::identifier)
576    Next = GetLookAheadToken(2);
577
578  switch (Next.getKind()) {
579  case tok::equal:
580  case tok::comma:
581  case tok::greater:
582  case tok::greatergreater:
583  case tok::ellipsis:
584    return TPResult::True;
585
586  case tok::kw_typename:
587  case tok::kw_typedef:
588  case tok::kw_class:
589    // These indicate that a comma was missed after a type parameter, not that
590    // we have found a non-type parameter.
591    return TPResult::True;
592
593  default:
594    return TPResult::False;
595  }
596}
597
598/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
599///
600///       template-parameter: [C++ temp.param]
601///         type-parameter
602///         parameter-declaration
603///
604///       type-parameter: (See below)
605///         type-parameter-key ...[opt] identifier[opt]
606///         type-parameter-key identifier[opt] = type-id
607/// (C++2a) type-constraint ...[opt] identifier[opt]
608/// (C++2a) type-constraint identifier[opt] = type-id
609///         'template' '<' template-parameter-list '>' type-parameter-key
610///               ...[opt] identifier[opt]
611///         'template' '<' template-parameter-list '>' type-parameter-key
612///               identifier[opt] '=' id-expression
613///
614///       type-parameter-key:
615///         class
616///         typename
617///
618NamedDecl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {
619
620  switch (isStartOfTemplateTypeParameter()) {
621  case TPResult::True:
622    // Is there just a typo in the input code? ('typedef' instead of
623    // 'typename')
624    if (Tok.is(tok::kw_typedef)) {
625      Diag(Tok.getLocation(), diag::err_expected_template_parameter);
626
627      Diag(Tok.getLocation(), diag::note_meant_to_use_typename)
628          << FixItHint::CreateReplacement(CharSourceRange::getCharRange(
629                                              Tok.getLocation(),
630                                              Tok.getEndLoc()),
631                                          "typename");
632
633      Tok.setKind(tok::kw_typename);
634    }
635
636    return ParseTypeParameter(Depth, Position);
637  case TPResult::False:
638    break;
639
640  case TPResult::Error: {
641    // We return an invalid parameter as opposed to null to avoid having bogus
642    // diagnostics about an empty template parameter list.
643    // FIXME: Fix ParseTemplateParameterList to better handle nullptr results
644    //  from here.
645    // Return a NTTP as if there was an error in a scope specifier, the user
646    // probably meant to write the type of a NTTP.
647    DeclSpec DS(getAttrFactory());
648    DS.SetTypeSpecError();
649    Declarator D(DS, DeclaratorContext::TemplateParamContext);
650    D.SetIdentifier(nullptr, Tok.getLocation());
651    D.setInvalidType(true);
652    NamedDecl *ErrorParam = Actions.ActOnNonTypeTemplateParameter(
653        getCurScope(), D, Depth, Position, /*EqualLoc=*/SourceLocation(),
654        /*DefaultArg=*/nullptr);
655    ErrorParam->setInvalidDecl(true);
656    SkipUntil(tok::comma, tok::greater, tok::greatergreater,
657              StopAtSemi | StopBeforeMatch);
658    return ErrorParam;
659  }
660
661  case TPResult::Ambiguous:
662    llvm_unreachable("template param classification can't be ambiguous");
663  }
664
665  if (Tok.is(tok::kw_template))
666    return ParseTemplateTemplateParameter(Depth, Position);
667
668  // If it's none of the above, then it must be a parameter declaration.
669  // NOTE: This will pick up errors in the closure of the template parameter
670  // list (e.g., template < ; Check here to implement >> style closures.
671  return ParseNonTypeTemplateParameter(Depth, Position);
672}
673
674/// Check whether the current token is a template-id annotation denoting a
675/// type-constraint.
676bool Parser::isTypeConstraintAnnotation() {
677  const Token &T = Tok.is(tok::annot_cxxscope) ? NextToken() : Tok;
678  if (T.isNot(tok::annot_template_id))
679    return false;
680  const auto *ExistingAnnot =
681      static_cast<TemplateIdAnnotation *>(T.getAnnotationValue());
682  return ExistingAnnot->Kind == TNK_Concept_template;
683}
684
685/// Try parsing a type-constraint at the current location.
686///
687///     type-constraint:
688///       nested-name-specifier[opt] concept-name
689///       nested-name-specifier[opt] concept-name
690///           '<' template-argument-list[opt] '>'[opt]
691///
692/// \returns true if an error occurred, and false otherwise.
693bool Parser::TryAnnotateTypeConstraint() {
694  if (!getLangOpts().CPlusPlus20)
695    return false;
696  CXXScopeSpec SS;
697  bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
698  if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
699                                     /*ObjectHadErrors=*/false,
700                                     /*EnteringContext=*/false,
701                                     /*MayBePseudoDestructor=*/nullptr,
702                                     // If this is not a type-constraint, then
703                                     // this scope-spec is part of the typename
704                                     // of a non-type template parameter
705                                     /*IsTypename=*/true, /*LastII=*/nullptr,
706                                     // We won't find concepts in
707                                     // non-namespaces anyway, so might as well
708                                     // parse this correctly for possible type
709                                     // names.
710                                     /*OnlyNamespace=*/false))
711    return true;
712
713  if (Tok.is(tok::identifier)) {
714    UnqualifiedId PossibleConceptName;
715    PossibleConceptName.setIdentifier(Tok.getIdentifierInfo(),
716                                      Tok.getLocation());
717
718    TemplateTy PossibleConcept;
719    bool MemberOfUnknownSpecialization = false;
720    auto TNK = Actions.isTemplateName(getCurScope(), SS,
721                                      /*hasTemplateKeyword=*/false,
722                                      PossibleConceptName,
723                                      /*ObjectType=*/ParsedType(),
724                                      /*EnteringContext=*/false,
725                                      PossibleConcept,
726                                      MemberOfUnknownSpecialization,
727                                      /*Disambiguation=*/true);
728    if (MemberOfUnknownSpecialization || !PossibleConcept ||
729        TNK != TNK_Concept_template) {
730      if (SS.isNotEmpty())
731        AnnotateScopeToken(SS, !WasScopeAnnotation);
732      return false;
733    }
734
735    // At this point we're sure we're dealing with a constrained parameter. It
736    // may or may not have a template parameter list following the concept
737    // name.
738    if (AnnotateTemplateIdToken(PossibleConcept, TNK, SS,
739                                   /*TemplateKWLoc=*/SourceLocation(),
740                                   PossibleConceptName,
741                                   /*AllowTypeAnnotation=*/false,
742                                   /*TypeConstraint=*/true))
743      return true;
744  }
745
746  if (SS.isNotEmpty())
747    AnnotateScopeToken(SS, !WasScopeAnnotation);
748  return false;
749}
750
751/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
752/// Other kinds of template parameters are parsed in
753/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
754///
755///       type-parameter:     [C++ temp.param]
756///         'class' ...[opt][C++0x] identifier[opt]
757///         'class' identifier[opt] '=' type-id
758///         'typename' ...[opt][C++0x] identifier[opt]
759///         'typename' identifier[opt] '=' type-id
760NamedDecl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
761  assert((Tok.isOneOf(tok::kw_class, tok::kw_typename) ||
762          isTypeConstraintAnnotation()) &&
763         "A type-parameter starts with 'class', 'typename' or a "
764         "type-constraint");
765
766  CXXScopeSpec TypeConstraintSS;
767  TemplateIdAnnotation *TypeConstraint = nullptr;
768  bool TypenameKeyword = false;
769  SourceLocation KeyLoc;
770  ParseOptionalCXXScopeSpecifier(TypeConstraintSS, /*ObjectType=*/nullptr,
771                                 /*ObjectHadErrors=*/false,
772                                 /*EnteringContext*/ false);
773  if (Tok.is(tok::annot_template_id)) {
774    // Consume the 'type-constraint'.
775    TypeConstraint =
776        static_cast<TemplateIdAnnotation *>(Tok.getAnnotationValue());
777    assert(TypeConstraint->Kind == TNK_Concept_template &&
778           "stray non-concept template-id annotation");
779    KeyLoc = ConsumeAnnotationToken();
780  } else {
781    assert(TypeConstraintSS.isEmpty() &&
782           "expected type constraint after scope specifier");
783
784    // Consume the 'class' or 'typename' keyword.
785    TypenameKeyword = Tok.is(tok::kw_typename);
786    KeyLoc = ConsumeToken();
787  }
788
789  // Grab the ellipsis (if given).
790  SourceLocation EllipsisLoc;
791  if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) {
792    Diag(EllipsisLoc,
793         getLangOpts().CPlusPlus11
794           ? diag::warn_cxx98_compat_variadic_templates
795           : diag::ext_variadic_templates);
796  }
797
798  // Grab the template parameter name (if given)
799  SourceLocation NameLoc = Tok.getLocation();
800  IdentifierInfo *ParamName = nullptr;
801  if (Tok.is(tok::identifier)) {
802    ParamName = Tok.getIdentifierInfo();
803    ConsumeToken();
804  } else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
805                         tok::greatergreater)) {
806    // Unnamed template parameter. Don't have to do anything here, just
807    // don't consume this token.
808  } else {
809    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
810    return nullptr;
811  }
812
813  // Recover from misplaced ellipsis.
814  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
815  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
816    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
817
818  // Grab a default argument (if available).
819  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
820  // we introduce the type parameter into the local scope.
821  SourceLocation EqualLoc;
822  ParsedType DefaultArg;
823  if (TryConsumeToken(tok::equal, EqualLoc))
824    DefaultArg = ParseTypeName(/*Range=*/nullptr,
825                               DeclaratorContext::TemplateTypeArgContext)
826                     .get();
827
828  NamedDecl *NewDecl = Actions.ActOnTypeParameter(getCurScope(),
829                                                  TypenameKeyword, EllipsisLoc,
830                                                  KeyLoc, ParamName, NameLoc,
831                                                  Depth, Position, EqualLoc,
832                                                  DefaultArg,
833                                                  TypeConstraint != nullptr);
834
835  if (TypeConstraint) {
836    Actions.ActOnTypeConstraint(TypeConstraintSS, TypeConstraint,
837                                cast<TemplateTypeParmDecl>(NewDecl),
838                                EllipsisLoc);
839  }
840
841  return NewDecl;
842}
843
844/// ParseTemplateTemplateParameter - Handle the parsing of template
845/// template parameters.
846///
847///       type-parameter:    [C++ temp.param]
848///         'template' '<' template-parameter-list '>' type-parameter-key
849///                  ...[opt] identifier[opt]
850///         'template' '<' template-parameter-list '>' type-parameter-key
851///                  identifier[opt] = id-expression
852///       type-parameter-key:
853///         'class'
854///         'typename'       [C++1z]
855NamedDecl *
856Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
857  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
858
859  // Handle the template <...> part.
860  SourceLocation TemplateLoc = ConsumeToken();
861  SmallVector<NamedDecl*,8> TemplateParams;
862  SourceLocation LAngleLoc, RAngleLoc;
863  {
864    MultiParseScope TemplateParmScope(*this);
865    if (ParseTemplateParameters(TemplateParmScope, Depth + 1, TemplateParams,
866                                LAngleLoc, RAngleLoc)) {
867      return nullptr;
868    }
869  }
870
871  // Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
872  // Generate a meaningful error if the user forgot to put class before the
873  // identifier, comma, or greater. Provide a fixit if the identifier, comma,
874  // or greater appear immediately or after 'struct'. In the latter case,
875  // replace the keyword with 'class'.
876  if (!TryConsumeToken(tok::kw_class)) {
877    bool Replace = Tok.isOneOf(tok::kw_typename, tok::kw_struct);
878    const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
879    if (Tok.is(tok::kw_typename)) {
880      Diag(Tok.getLocation(),
881           getLangOpts().CPlusPlus17
882               ? diag::warn_cxx14_compat_template_template_param_typename
883               : diag::ext_template_template_param_typename)
884        << (!getLangOpts().CPlusPlus17
885                ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
886                : FixItHint());
887    } else if (Next.isOneOf(tok::identifier, tok::comma, tok::greater,
888                            tok::greatergreater, tok::ellipsis)) {
889      Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
890        << (Replace ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
891                    : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
892    } else
893      Diag(Tok.getLocation(), diag::err_class_on_template_template_param);
894
895    if (Replace)
896      ConsumeToken();
897  }
898
899  // Parse the ellipsis, if given.
900  SourceLocation EllipsisLoc;
901  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
902    Diag(EllipsisLoc,
903         getLangOpts().CPlusPlus11
904           ? diag::warn_cxx98_compat_variadic_templates
905           : diag::ext_variadic_templates);
906
907  // Get the identifier, if given.
908  SourceLocation NameLoc = Tok.getLocation();
909  IdentifierInfo *ParamName = nullptr;
910  if (Tok.is(tok::identifier)) {
911    ParamName = Tok.getIdentifierInfo();
912    ConsumeToken();
913  } else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
914                         tok::greatergreater)) {
915    // Unnamed template parameter. Don't have to do anything here, just
916    // don't consume this token.
917  } else {
918    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
919    return nullptr;
920  }
921
922  // Recover from misplaced ellipsis.
923  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
924  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
925    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
926
927  TemplateParameterList *ParamList =
928    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
929                                       TemplateLoc, LAngleLoc,
930                                       TemplateParams,
931                                       RAngleLoc, nullptr);
932
933  // Grab a default argument (if available).
934  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
935  // we introduce the template parameter into the local scope.
936  SourceLocation EqualLoc;
937  ParsedTemplateArgument DefaultArg;
938  if (TryConsumeToken(tok::equal, EqualLoc)) {
939    DefaultArg = ParseTemplateTemplateArgument();
940    if (DefaultArg.isInvalid()) {
941      Diag(Tok.getLocation(),
942           diag::err_default_template_template_parameter_not_template);
943      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
944                StopAtSemi | StopBeforeMatch);
945    }
946  }
947
948  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
949                                                ParamList, EllipsisLoc,
950                                                ParamName, NameLoc, Depth,
951                                                Position, EqualLoc, DefaultArg);
952}
953
954/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
955/// template parameters (e.g., in "template<int Size> class array;").
956///
957///       template-parameter:
958///         ...
959///         parameter-declaration
960NamedDecl *
961Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
962  // Parse the declaration-specifiers (i.e., the type).
963  // FIXME: The type should probably be restricted in some way... Not all
964  // declarators (parts of declarators?) are accepted for parameters.
965  DeclSpec DS(AttrFactory);
966  ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS_none,
967                             DeclSpecContext::DSC_template_param);
968
969  // Parse this as a typename.
970  Declarator ParamDecl(DS, DeclaratorContext::TemplateParamContext);
971  ParseDeclarator(ParamDecl);
972  if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
973    Diag(Tok.getLocation(), diag::err_expected_template_parameter);
974    return nullptr;
975  }
976
977  // Recover from misplaced ellipsis.
978  SourceLocation EllipsisLoc;
979  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
980    DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, ParamDecl);
981
982  // If there is a default value, parse it.
983  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
984  // we introduce the template parameter into the local scope.
985  SourceLocation EqualLoc;
986  ExprResult DefaultArg;
987  if (TryConsumeToken(tok::equal, EqualLoc)) {
988    // C++ [temp.param]p15:
989    //   When parsing a default template-argument for a non-type
990    //   template-parameter, the first non-nested > is taken as the
991    //   end of the template-parameter-list rather than a greater-than
992    //   operator.
993    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
994    EnterExpressionEvaluationContext ConstantEvaluated(
995        Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
996
997    DefaultArg = Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression());
998    if (DefaultArg.isInvalid())
999      SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
1000  }
1001
1002  // Create the parameter.
1003  return Actions.ActOnNonTypeTemplateParameter(getCurScope(), ParamDecl,
1004                                               Depth, Position, EqualLoc,
1005                                               DefaultArg.get());
1006}
1007
1008void Parser::DiagnoseMisplacedEllipsis(SourceLocation EllipsisLoc,
1009                                       SourceLocation CorrectLoc,
1010                                       bool AlreadyHasEllipsis,
1011                                       bool IdentifierHasName) {
1012  FixItHint Insertion;
1013  if (!AlreadyHasEllipsis)
1014    Insertion = FixItHint::CreateInsertion(CorrectLoc, "...");
1015  Diag(EllipsisLoc, diag::err_misplaced_ellipsis_in_declaration)
1016      << FixItHint::CreateRemoval(EllipsisLoc) << Insertion
1017      << !IdentifierHasName;
1018}
1019
1020void Parser::DiagnoseMisplacedEllipsisInDeclarator(SourceLocation EllipsisLoc,
1021                                                   Declarator &D) {
1022  assert(EllipsisLoc.isValid());
1023  bool AlreadyHasEllipsis = D.getEllipsisLoc().isValid();
1024  if (!AlreadyHasEllipsis)
1025    D.setEllipsisLoc(EllipsisLoc);
1026  DiagnoseMisplacedEllipsis(EllipsisLoc, D.getIdentifierLoc(),
1027                            AlreadyHasEllipsis, D.hasName());
1028}
1029
1030/// Parses a '>' at the end of a template list.
1031///
1032/// If this function encounters '>>', '>>>', '>=', or '>>=', it tries
1033/// to determine if these tokens were supposed to be a '>' followed by
1034/// '>', '>>', '>=', or '>='. It emits an appropriate diagnostic if necessary.
1035///
1036/// \param RAngleLoc the location of the consumed '>'.
1037///
1038/// \param ConsumeLastToken if true, the '>' is consumed.
1039///
1040/// \param ObjCGenericList if true, this is the '>' closing an Objective-C
1041/// type parameter or type argument list, rather than a C++ template parameter
1042/// or argument list.
1043///
1044/// \returns true, if current token does not start with '>', false otherwise.
1045bool Parser::ParseGreaterThanInTemplateList(SourceLocation LAngleLoc,
1046                                            SourceLocation &RAngleLoc,
1047                                            bool ConsumeLastToken,
1048                                            bool ObjCGenericList) {
1049  // What will be left once we've consumed the '>'.
1050  tok::TokenKind RemainingToken;
1051  const char *ReplacementStr = "> >";
1052  bool MergeWithNextToken = false;
1053
1054  switch (Tok.getKind()) {
1055  default:
1056    Diag(getEndOfPreviousToken(), diag::err_expected) << tok::greater;
1057    Diag(LAngleLoc, diag::note_matching) << tok::less;
1058    return true;
1059
1060  case tok::greater:
1061    // Determine the location of the '>' token. Only consume this token
1062    // if the caller asked us to.
1063    RAngleLoc = Tok.getLocation();
1064    if (ConsumeLastToken)
1065      ConsumeToken();
1066    return false;
1067
1068  case tok::greatergreater:
1069    RemainingToken = tok::greater;
1070    break;
1071
1072  case tok::greatergreatergreater:
1073    RemainingToken = tok::greatergreater;
1074    break;
1075
1076  case tok::greaterequal:
1077    RemainingToken = tok::equal;
1078    ReplacementStr = "> =";
1079
1080    // Join two adjacent '=' tokens into one, for cases like:
1081    //   void (*p)() = f<int>;
1082    //   return f<int>==p;
1083    if (NextToken().is(tok::equal) &&
1084        areTokensAdjacent(Tok, NextToken())) {
1085      RemainingToken = tok::equalequal;
1086      MergeWithNextToken = true;
1087    }
1088    break;
1089
1090  case tok::greatergreaterequal:
1091    RemainingToken = tok::greaterequal;
1092    break;
1093  }
1094
1095  // This template-id is terminated by a token that starts with a '>'.
1096  // Outside C++11 and Objective-C, this is now error recovery.
1097  //
1098  // C++11 allows this when the token is '>>', and in CUDA + C++11 mode, we
1099  // extend that treatment to also apply to the '>>>' token.
1100  //
1101  // Objective-C allows this in its type parameter / argument lists.
1102
1103  SourceLocation TokBeforeGreaterLoc = PrevTokLocation;
1104  SourceLocation TokLoc = Tok.getLocation();
1105  Token Next = NextToken();
1106
1107  // Whether splitting the current token after the '>' would undesirably result
1108  // in the remaining token pasting with the token after it. This excludes the
1109  // MergeWithNextToken cases, which we've already handled.
1110  bool PreventMergeWithNextToken =
1111      (RemainingToken == tok::greater ||
1112       RemainingToken == tok::greatergreater) &&
1113      (Next.isOneOf(tok::greater, tok::greatergreater,
1114                    tok::greatergreatergreater, tok::equal, tok::greaterequal,
1115                    tok::greatergreaterequal, tok::equalequal)) &&
1116      areTokensAdjacent(Tok, Next);
1117
1118  // Diagnose this situation as appropriate.
1119  if (!ObjCGenericList) {
1120    // The source range of the replaced token(s).
1121    CharSourceRange ReplacementRange = CharSourceRange::getCharRange(
1122        TokLoc, Lexer::AdvanceToTokenCharacter(TokLoc, 2, PP.getSourceManager(),
1123                                               getLangOpts()));
1124
1125    // A hint to put a space between the '>>'s. In order to make the hint as
1126    // clear as possible, we include the characters either side of the space in
1127    // the replacement, rather than just inserting a space at SecondCharLoc.
1128    FixItHint Hint1 = FixItHint::CreateReplacement(ReplacementRange,
1129                                                   ReplacementStr);
1130
1131    // A hint to put another space after the token, if it would otherwise be
1132    // lexed differently.
1133    FixItHint Hint2;
1134    if (PreventMergeWithNextToken)
1135      Hint2 = FixItHint::CreateInsertion(Next.getLocation(), " ");
1136
1137    unsigned DiagId = diag::err_two_right_angle_brackets_need_space;
1138    if (getLangOpts().CPlusPlus11 &&
1139        (Tok.is(tok::greatergreater) || Tok.is(tok::greatergreatergreater)))
1140      DiagId = diag::warn_cxx98_compat_two_right_angle_brackets;
1141    else if (Tok.is(tok::greaterequal))
1142      DiagId = diag::err_right_angle_bracket_equal_needs_space;
1143    Diag(TokLoc, DiagId) << Hint1 << Hint2;
1144  }
1145
1146  // Find the "length" of the resulting '>' token. This is not always 1, as it
1147  // can contain escaped newlines.
1148  unsigned GreaterLength = Lexer::getTokenPrefixLength(
1149      TokLoc, 1, PP.getSourceManager(), getLangOpts());
1150
1151  // Annotate the source buffer to indicate that we split the token after the
1152  // '>'. This allows us to properly find the end of, and extract the spelling
1153  // of, the '>' token later.
1154  RAngleLoc = PP.SplitToken(TokLoc, GreaterLength);
1155
1156  // Strip the initial '>' from the token.
1157  bool CachingTokens = PP.IsPreviousCachedToken(Tok);
1158
1159  Token Greater = Tok;
1160  Greater.setLocation(RAngleLoc);
1161  Greater.setKind(tok::greater);
1162  Greater.setLength(GreaterLength);
1163
1164  unsigned OldLength = Tok.getLength();
1165  if (MergeWithNextToken) {
1166    ConsumeToken();
1167    OldLength += Tok.getLength();
1168  }
1169
1170  Tok.setKind(RemainingToken);
1171  Tok.setLength(OldLength - GreaterLength);
1172
1173  // Split the second token if lexing it normally would lex a different token
1174  // (eg, the fifth token in 'A<B>>>' should re-lex as '>', not '>>').
1175  SourceLocation AfterGreaterLoc = TokLoc.getLocWithOffset(GreaterLength);
1176  if (PreventMergeWithNextToken)
1177    AfterGreaterLoc = PP.SplitToken(AfterGreaterLoc, Tok.getLength());
1178  Tok.setLocation(AfterGreaterLoc);
1179
1180  // Update the token cache to match what we just did if necessary.
1181  if (CachingTokens) {
1182    // If the previous cached token is being merged, delete it.
1183    if (MergeWithNextToken)
1184      PP.ReplacePreviousCachedToken({});
1185
1186    if (ConsumeLastToken)
1187      PP.ReplacePreviousCachedToken({Greater, Tok});
1188    else
1189      PP.ReplacePreviousCachedToken({Greater});
1190  }
1191
1192  if (ConsumeLastToken) {
1193    PrevTokLocation = RAngleLoc;
1194  } else {
1195    PrevTokLocation = TokBeforeGreaterLoc;
1196    PP.EnterToken(Tok, /*IsReinject=*/true);
1197    Tok = Greater;
1198  }
1199
1200  return false;
1201}
1202
1203
1204/// Parses a template-id that after the template name has
1205/// already been parsed.
1206///
1207/// This routine takes care of parsing the enclosed template argument
1208/// list ('<' template-parameter-list [opt] '>') and placing the
1209/// results into a form that can be transferred to semantic analysis.
1210///
1211/// \param ConsumeLastToken if true, then we will consume the last
1212/// token that forms the template-id. Otherwise, we will leave the
1213/// last token in the stream (e.g., so that it can be replaced with an
1214/// annotation token).
1215bool
1216Parser::ParseTemplateIdAfterTemplateName(bool ConsumeLastToken,
1217                                         SourceLocation &LAngleLoc,
1218                                         TemplateArgList &TemplateArgs,
1219                                         SourceLocation &RAngleLoc) {
1220  assert(Tok.is(tok::less) && "Must have already parsed the template-name");
1221
1222  // Consume the '<'.
1223  LAngleLoc = ConsumeToken();
1224
1225  // Parse the optional template-argument-list.
1226  bool Invalid = false;
1227  {
1228    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
1229    if (!Tok.isOneOf(tok::greater, tok::greatergreater,
1230                     tok::greatergreatergreater, tok::greaterequal,
1231                     tok::greatergreaterequal))
1232      Invalid = ParseTemplateArgumentList(TemplateArgs);
1233
1234    if (Invalid) {
1235      // Try to find the closing '>'.
1236      if (getLangOpts().CPlusPlus11)
1237        SkipUntil(tok::greater, tok::greatergreater,
1238                  tok::greatergreatergreater, StopAtSemi | StopBeforeMatch);
1239      else
1240        SkipUntil(tok::greater, StopAtSemi | StopBeforeMatch);
1241    }
1242  }
1243
1244  return ParseGreaterThanInTemplateList(LAngleLoc, RAngleLoc, ConsumeLastToken,
1245                                        /*ObjCGenericList=*/false) ||
1246         Invalid;
1247}
1248
1249/// Replace the tokens that form a simple-template-id with an
1250/// annotation token containing the complete template-id.
1251///
1252/// The first token in the stream must be the name of a template that
1253/// is followed by a '<'. This routine will parse the complete
1254/// simple-template-id and replace the tokens with a single annotation
1255/// token with one of two different kinds: if the template-id names a
1256/// type (and \p AllowTypeAnnotation is true), the annotation token is
1257/// a type annotation that includes the optional nested-name-specifier
1258/// (\p SS). Otherwise, the annotation token is a template-id
1259/// annotation that does not include the optional
1260/// nested-name-specifier.
1261///
1262/// \param Template  the declaration of the template named by the first
1263/// token (an identifier), as returned from \c Action::isTemplateName().
1264///
1265/// \param TNK the kind of template that \p Template
1266/// refers to, as returned from \c Action::isTemplateName().
1267///
1268/// \param SS if non-NULL, the nested-name-specifier that precedes
1269/// this template name.
1270///
1271/// \param TemplateKWLoc if valid, specifies that this template-id
1272/// annotation was preceded by the 'template' keyword and gives the
1273/// location of that keyword. If invalid (the default), then this
1274/// template-id was not preceded by a 'template' keyword.
1275///
1276/// \param AllowTypeAnnotation if true (the default), then a
1277/// simple-template-id that refers to a class template, template
1278/// template parameter, or other template that produces a type will be
1279/// replaced with a type annotation token. Otherwise, the
1280/// simple-template-id is always replaced with a template-id
1281/// annotation token.
1282///
1283/// \param TypeConstraint if true, then this is actually a type-constraint,
1284/// meaning that the template argument list can be omitted (and the template in
1285/// question must be a concept).
1286///
1287/// If an unrecoverable parse error occurs and no annotation token can be
1288/// formed, this function returns true.
1289///
1290bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
1291                                     CXXScopeSpec &SS,
1292                                     SourceLocation TemplateKWLoc,
1293                                     UnqualifiedId &TemplateName,
1294                                     bool AllowTypeAnnotation,
1295                                     bool TypeConstraint) {
1296  assert(getLangOpts().CPlusPlus && "Can only annotate template-ids in C++");
1297  assert((Tok.is(tok::less) || TypeConstraint) &&
1298         "Parser isn't at the beginning of a template-id");
1299  assert(!(TypeConstraint && AllowTypeAnnotation) && "type-constraint can't be "
1300                                                     "a type annotation");
1301  assert((!TypeConstraint || TNK == TNK_Concept_template) && "type-constraint "
1302         "must accompany a concept name");
1303  assert((Template || TNK == TNK_Non_template) && "missing template name");
1304
1305  // Consume the template-name.
1306  SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();
1307
1308  // Parse the enclosed template argument list.
1309  SourceLocation LAngleLoc, RAngleLoc;
1310  TemplateArgList TemplateArgs;
1311  bool ArgsInvalid = false;
1312  if (!TypeConstraint || Tok.is(tok::less)) {
1313    ArgsInvalid = ParseTemplateIdAfterTemplateName(false, LAngleLoc,
1314                                                   TemplateArgs, RAngleLoc);
1315    // If we couldn't recover from invalid arguments, don't form an annotation
1316    // token -- we don't know how much to annotate.
1317    // FIXME: This can lead to duplicate diagnostics if we retry parsing this
1318    // template-id in another context. Try to annotate anyway?
1319    if (RAngleLoc.isInvalid())
1320      return true;
1321  }
1322
1323  ASTTemplateArgsPtr TemplateArgsPtr(TemplateArgs);
1324
1325  // Build the annotation token.
1326  if (TNK == TNK_Type_template && AllowTypeAnnotation) {
1327    TypeResult Type = ArgsInvalid
1328                          ? TypeError()
1329                          : Actions.ActOnTemplateIdType(
1330                                getCurScope(), SS, TemplateKWLoc, Template,
1331                                TemplateName.Identifier, TemplateNameLoc,
1332                                LAngleLoc, TemplateArgsPtr, RAngleLoc);
1333
1334    Tok.setKind(tok::annot_typename);
1335    setTypeAnnotation(Tok, Type);
1336    if (SS.isNotEmpty())
1337      Tok.setLocation(SS.getBeginLoc());
1338    else if (TemplateKWLoc.isValid())
1339      Tok.setLocation(TemplateKWLoc);
1340    else
1341      Tok.setLocation(TemplateNameLoc);
1342  } else {
1343    // Build a template-id annotation token that can be processed
1344    // later.
1345    Tok.setKind(tok::annot_template_id);
1346
1347    IdentifierInfo *TemplateII =
1348        TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
1349            ? TemplateName.Identifier
1350            : nullptr;
1351
1352    OverloadedOperatorKind OpKind =
1353        TemplateName.getKind() == UnqualifiedIdKind::IK_Identifier
1354            ? OO_None
1355            : TemplateName.OperatorFunctionId.Operator;
1356
1357    TemplateIdAnnotation *TemplateId = TemplateIdAnnotation::Create(
1358        TemplateKWLoc, TemplateNameLoc, TemplateII, OpKind, Template, TNK,
1359        LAngleLoc, RAngleLoc, TemplateArgs, ArgsInvalid, TemplateIds);
1360
1361    Tok.setAnnotationValue(TemplateId);
1362    if (TemplateKWLoc.isValid())
1363      Tok.setLocation(TemplateKWLoc);
1364    else
1365      Tok.setLocation(TemplateNameLoc);
1366  }
1367
1368  // Common fields for the annotation token
1369  Tok.setAnnotationEndLoc(RAngleLoc);
1370
1371  // In case the tokens were cached, have Preprocessor replace them with the
1372  // annotation token.
1373  PP.AnnotateCachedTokens(Tok);
1374  return false;
1375}
1376
1377/// Replaces a template-id annotation token with a type
1378/// annotation token.
1379///
1380/// If there was a failure when forming the type from the template-id,
1381/// a type annotation token will still be created, but will have a
1382/// NULL type pointer to signify an error.
1383///
1384/// \param SS The scope specifier appearing before the template-id, if any.
1385///
1386/// \param IsClassName Is this template-id appearing in a context where we
1387/// know it names a class, such as in an elaborated-type-specifier or
1388/// base-specifier? ('typename' and 'template' are unneeded and disallowed
1389/// in those contexts.)
1390void Parser::AnnotateTemplateIdTokenAsType(CXXScopeSpec &SS,
1391                                           bool IsClassName) {
1392  assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens");
1393
1394  TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
1395  assert(TemplateId->mightBeType() &&
1396         "Only works for type and dependent templates");
1397
1398  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
1399                                     TemplateId->NumArgs);
1400
1401  TypeResult Type =
1402      TemplateId->isInvalid()
1403          ? TypeError()
1404          : Actions.ActOnTemplateIdType(
1405                getCurScope(), SS, TemplateId->TemplateKWLoc,
1406                TemplateId->Template, TemplateId->Name,
1407                TemplateId->TemplateNameLoc, TemplateId->LAngleLoc,
1408                TemplateArgsPtr, TemplateId->RAngleLoc,
1409                /*IsCtorOrDtorName*/ false, IsClassName);
1410  // Create the new "type" annotation token.
1411  Tok.setKind(tok::annot_typename);
1412  setTypeAnnotation(Tok, Type);
1413  if (SS.isNotEmpty()) // it was a C++ qualified type name.
1414    Tok.setLocation(SS.getBeginLoc());
1415  // End location stays the same
1416
1417  // Replace the template-id annotation token, and possible the scope-specifier
1418  // that precedes it, with the typename annotation token.
1419  PP.AnnotateCachedTokens(Tok);
1420}
1421
1422/// Determine whether the given token can end a template argument.
1423static bool isEndOfTemplateArgument(Token Tok) {
1424  // FIXME: Handle '>>>'.
1425  return Tok.isOneOf(tok::comma, tok::greater, tok::greatergreater,
1426                     tok::greatergreatergreater);
1427}
1428
1429/// Parse a C++ template template argument.
1430ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
1431  if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
1432      !Tok.is(tok::annot_cxxscope))
1433    return ParsedTemplateArgument();
1434
1435  // C++0x [temp.arg.template]p1:
1436  //   A template-argument for a template template-parameter shall be the name
1437  //   of a class template or an alias template, expressed as id-expression.
1438  //
1439  // We parse an id-expression that refers to a class template or alias
1440  // template. The grammar we parse is:
1441  //
1442  //   nested-name-specifier[opt] template[opt] identifier ...[opt]
1443  //
1444  // followed by a token that terminates a template argument, such as ',',
1445  // '>', or (in some cases) '>>'.
1446  CXXScopeSpec SS; // nested-name-specifier, if present
1447  ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
1448                                 /*ObjectHadErrors=*/false,
1449                                 /*EnteringContext=*/false);
1450
1451  ParsedTemplateArgument Result;
1452  SourceLocation EllipsisLoc;
1453  if (SS.isSet() && Tok.is(tok::kw_template)) {
1454    // Parse the optional 'template' keyword following the
1455    // nested-name-specifier.
1456    SourceLocation TemplateKWLoc = ConsumeToken();
1457
1458    if (Tok.is(tok::identifier)) {
1459      // We appear to have a dependent template name.
1460      UnqualifiedId Name;
1461      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1462      ConsumeToken(); // the identifier
1463
1464      TryConsumeToken(tok::ellipsis, EllipsisLoc);
1465
1466      // If the next token signals the end of a template argument, then we have
1467      // a (possibly-dependent) template name that could be a template template
1468      // argument.
1469      TemplateTy Template;
1470      if (isEndOfTemplateArgument(Tok) &&
1471          Actions.ActOnTemplateName(getCurScope(), SS, TemplateKWLoc, Name,
1472                                    /*ObjectType=*/nullptr,
1473                                    /*EnteringContext=*/false, Template))
1474        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1475    }
1476  } else if (Tok.is(tok::identifier)) {
1477    // We may have a (non-dependent) template name.
1478    TemplateTy Template;
1479    UnqualifiedId Name;
1480    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1481    ConsumeToken(); // the identifier
1482
1483    TryConsumeToken(tok::ellipsis, EllipsisLoc);
1484
1485    if (isEndOfTemplateArgument(Tok)) {
1486      bool MemberOfUnknownSpecialization;
1487      TemplateNameKind TNK = Actions.isTemplateName(
1488          getCurScope(), SS,
1489          /*hasTemplateKeyword=*/false, Name,
1490          /*ObjectType=*/nullptr,
1491          /*EnteringContext=*/false, Template, MemberOfUnknownSpecialization);
1492      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
1493        // We have an id-expression that refers to a class template or
1494        // (C++0x) alias template.
1495        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1496      }
1497    }
1498  }
1499
1500  // If this is a pack expansion, build it as such.
1501  if (EllipsisLoc.isValid() && !Result.isInvalid())
1502    Result = Actions.ActOnPackExpansion(Result, EllipsisLoc);
1503
1504  return Result;
1505}
1506
1507/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
1508///
1509///       template-argument: [C++ 14.2]
1510///         constant-expression
1511///         type-id
1512///         id-expression
1513ParsedTemplateArgument Parser::ParseTemplateArgument() {
1514  // C++ [temp.arg]p2:
1515  //   In a template-argument, an ambiguity between a type-id and an
1516  //   expression is resolved to a type-id, regardless of the form of
1517  //   the corresponding template-parameter.
1518  //
1519  // Therefore, we initially try to parse a type-id - and isCXXTypeId might look
1520  // up and annotate an identifier as an id-expression during disambiguation,
1521  // so enter the appropriate context for a constant expression template
1522  // argument before trying to disambiguate.
1523
1524  EnterExpressionEvaluationContext EnterConstantEvaluated(
1525    Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated,
1526    /*LambdaContextDecl=*/nullptr,
1527    /*ExprContext=*/Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
1528  if (isCXXTypeId(TypeIdAsTemplateArgument)) {
1529    TypeResult TypeArg = ParseTypeName(
1530        /*Range=*/nullptr, DeclaratorContext::TemplateArgContext);
1531    return Actions.ActOnTemplateTypeArgument(TypeArg);
1532  }
1533
1534  // Try to parse a template template argument.
1535  {
1536    TentativeParsingAction TPA(*this);
1537
1538    ParsedTemplateArgument TemplateTemplateArgument
1539      = ParseTemplateTemplateArgument();
1540    if (!TemplateTemplateArgument.isInvalid()) {
1541      TPA.Commit();
1542      return TemplateTemplateArgument;
1543    }
1544
1545    // Revert this tentative parse to parse a non-type template argument.
1546    TPA.Revert();
1547  }
1548
1549  // Parse a non-type template argument.
1550  SourceLocation Loc = Tok.getLocation();
1551  ExprResult ExprArg = ParseConstantExpressionInExprEvalContext(MaybeTypeCast);
1552  if (ExprArg.isInvalid() || !ExprArg.get()) {
1553    return ParsedTemplateArgument();
1554  }
1555
1556  return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
1557                                ExprArg.get(), Loc);
1558}
1559
1560/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1561/// (C++ [temp.names]). Returns true if there was an error.
1562///
1563///       template-argument-list: [C++ 14.2]
1564///         template-argument
1565///         template-argument-list ',' template-argument
1566bool
1567Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {
1568
1569  ColonProtectionRAIIObject ColonProtection(*this, false);
1570
1571  do {
1572    ParsedTemplateArgument Arg = ParseTemplateArgument();
1573    SourceLocation EllipsisLoc;
1574    if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
1575      Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);
1576
1577    if (Arg.isInvalid())
1578      return true;
1579
1580    // Save this template argument.
1581    TemplateArgs.push_back(Arg);
1582
1583    // If the next token is a comma, consume it and keep reading
1584    // arguments.
1585  } while (TryConsumeToken(tok::comma));
1586
1587  return false;
1588}
1589
1590/// Parse a C++ explicit template instantiation
1591/// (C++ [temp.explicit]).
1592///
1593///       explicit-instantiation:
1594///         'extern' [opt] 'template' declaration
1595///
1596/// Note that the 'extern' is a GNU extension and C++11 feature.
1597Decl *Parser::ParseExplicitInstantiation(DeclaratorContext Context,
1598                                         SourceLocation ExternLoc,
1599                                         SourceLocation TemplateLoc,
1600                                         SourceLocation &DeclEnd,
1601                                         ParsedAttributes &AccessAttrs,
1602                                         AccessSpecifier AS) {
1603  // This isn't really required here.
1604  ParsingDeclRAIIObject
1605    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
1606
1607  return ParseSingleDeclarationAfterTemplate(
1608      Context, ParsedTemplateInfo(ExternLoc, TemplateLoc),
1609      ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
1610}
1611
1612SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
1613  if (TemplateParams)
1614    return getTemplateParamsRange(TemplateParams->data(),
1615                                  TemplateParams->size());
1616
1617  SourceRange R(TemplateLoc);
1618  if (ExternLoc.isValid())
1619    R.setBegin(ExternLoc);
1620  return R;
1621}
1622
1623void Parser::LateTemplateParserCallback(void *P, LateParsedTemplate &LPT) {
1624  ((Parser *)P)->ParseLateTemplatedFuncDef(LPT);
1625}
1626
1627/// Late parse a C++ function template in Microsoft mode.
1628void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
1629  if (!LPT.D)
1630     return;
1631
1632  // Destroy TemplateIdAnnotations when we're done, if possible.
1633  DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(*this);
1634
1635  // Get the FunctionDecl.
1636  FunctionDecl *FunD = LPT.D->getAsFunction();
1637  // Track template parameter depth.
1638  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
1639
1640  // To restore the context after late parsing.
1641  Sema::ContextRAII GlobalSavedContext(
1642      Actions, Actions.Context.getTranslationUnitDecl());
1643
1644  MultiParseScope Scopes(*this);
1645
1646  // Get the list of DeclContexts to reenter.
1647  SmallVector<DeclContext*, 4> DeclContextsToReenter;
1648  for (DeclContext *DC = FunD; DC && !DC->isTranslationUnit();
1649       DC = DC->getLexicalParent())
1650    DeclContextsToReenter.push_back(DC);
1651
1652  // Reenter scopes from outermost to innermost.
1653  for (DeclContext *DC : reverse(DeclContextsToReenter)) {
1654    CurTemplateDepthTracker.addDepth(
1655        ReenterTemplateScopes(Scopes, cast<Decl>(DC)));
1656    Scopes.Enter(Scope::DeclScope);
1657    // We'll reenter the function context itself below.
1658    if (DC != FunD)
1659      Actions.PushDeclContext(Actions.getCurScope(), DC);
1660  }
1661
1662  assert(!LPT.Toks.empty() && "Empty body!");
1663
1664  // Append the current token at the end of the new token stream so that it
1665  // doesn't get lost.
1666  LPT.Toks.push_back(Tok);
1667  PP.EnterTokenStream(LPT.Toks, true, /*IsReinject*/true);
1668
1669  // Consume the previously pushed token.
1670  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
1671  assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try) &&
1672         "Inline method not starting with '{', ':' or 'try'");
1673
1674  // Parse the method body. Function body parsing code is similar enough
1675  // to be re-used for method bodies as well.
1676  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope |
1677                               Scope::CompoundStmtScope);
1678
1679  // Recreate the containing function DeclContext.
1680  Sema::ContextRAII FunctionSavedContext(Actions, FunD->getLexicalParent());
1681
1682  Actions.ActOnStartOfFunctionDef(getCurScope(), FunD);
1683
1684  if (Tok.is(tok::kw_try)) {
1685    ParseFunctionTryBlock(LPT.D, FnScope);
1686  } else {
1687    if (Tok.is(tok::colon))
1688      ParseConstructorInitializer(LPT.D);
1689    else
1690      Actions.ActOnDefaultCtorInitializers(LPT.D);
1691
1692    if (Tok.is(tok::l_brace)) {
1693      assert((!isa<FunctionTemplateDecl>(LPT.D) ||
1694              cast<FunctionTemplateDecl>(LPT.D)
1695                      ->getTemplateParameters()
1696                      ->getDepth() == TemplateParameterDepth - 1) &&
1697             "TemplateParameterDepth should be greater than the depth of "
1698             "current template being instantiated!");
1699      ParseFunctionStatementBody(LPT.D, FnScope);
1700      Actions.UnmarkAsLateParsedTemplate(FunD);
1701    } else
1702      Actions.ActOnFinishFunctionBody(LPT.D, nullptr);
1703  }
1704}
1705
1706/// Lex a delayed template function for late parsing.
1707void Parser::LexTemplateFunctionForLateParsing(CachedTokens &Toks) {
1708  tok::TokenKind kind = Tok.getKind();
1709  if (!ConsumeAndStoreFunctionPrologue(Toks)) {
1710    // Consume everything up to (and including) the matching right brace.
1711    ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1712  }
1713
1714  // If we're in a function-try-block, we need to store all the catch blocks.
1715  if (kind == tok::kw_try) {
1716    while (Tok.is(tok::kw_catch)) {
1717      ConsumeAndStoreUntil(tok::l_brace, Toks, /*StopAtSemi=*/false);
1718      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1719    }
1720  }
1721}
1722
1723/// We've parsed something that could plausibly be intended to be a template
1724/// name (\p LHS) followed by a '<' token, and the following code can't possibly
1725/// be an expression. Determine if this is likely to be a template-id and if so,
1726/// diagnose it.
1727bool Parser::diagnoseUnknownTemplateId(ExprResult LHS, SourceLocation Less) {
1728  TentativeParsingAction TPA(*this);
1729  // FIXME: We could look at the token sequence in a lot more detail here.
1730  if (SkipUntil(tok::greater, tok::greatergreater, tok::greatergreatergreater,
1731                StopAtSemi | StopBeforeMatch)) {
1732    TPA.Commit();
1733
1734    SourceLocation Greater;
1735    ParseGreaterThanInTemplateList(Less, Greater, true, false);
1736    Actions.diagnoseExprIntendedAsTemplateName(getCurScope(), LHS,
1737                                               Less, Greater);
1738    return true;
1739  }
1740
1741  // There's no matching '>' token, this probably isn't supposed to be
1742  // interpreted as a template-id. Parse it as an (ill-formed) comparison.
1743  TPA.Revert();
1744  return false;
1745}
1746
1747void Parser::checkPotentialAngleBracket(ExprResult &PotentialTemplateName) {
1748  assert(Tok.is(tok::less) && "not at a potential angle bracket");
1749
1750  bool DependentTemplateName = false;
1751  if (!Actions.mightBeIntendedToBeTemplateName(PotentialTemplateName,
1752                                               DependentTemplateName))
1753    return;
1754
1755  // OK, this might be a name that the user intended to be parsed as a
1756  // template-name, followed by a '<' token. Check for some easy cases.
1757
1758  // If we have potential_template<>, then it's supposed to be a template-name.
1759  if (NextToken().is(tok::greater) ||
1760      (getLangOpts().CPlusPlus11 &&
1761       NextToken().isOneOf(tok::greatergreater, tok::greatergreatergreater))) {
1762    SourceLocation Less = ConsumeToken();
1763    SourceLocation Greater;
1764    ParseGreaterThanInTemplateList(Less, Greater, true, false);
1765    Actions.diagnoseExprIntendedAsTemplateName(
1766        getCurScope(), PotentialTemplateName, Less, Greater);
1767    // FIXME: Perform error recovery.
1768    PotentialTemplateName = ExprError();
1769    return;
1770  }
1771
1772  // If we have 'potential_template<type-id', assume it's supposed to be a
1773  // template-name if there's a matching '>' later on.
1774  {
1775    // FIXME: Avoid the tentative parse when NextToken() can't begin a type.
1776    TentativeParsingAction TPA(*this);
1777    SourceLocation Less = ConsumeToken();
1778    if (isTypeIdUnambiguously() &&
1779        diagnoseUnknownTemplateId(PotentialTemplateName, Less)) {
1780      TPA.Commit();
1781      // FIXME: Perform error recovery.
1782      PotentialTemplateName = ExprError();
1783      return;
1784    }
1785    TPA.Revert();
1786  }
1787
1788  // Otherwise, remember that we saw this in case we see a potentially-matching
1789  // '>' token later on.
1790  AngleBracketTracker::Priority Priority =
1791      (DependentTemplateName ? AngleBracketTracker::DependentName
1792                             : AngleBracketTracker::PotentialTypo) |
1793      (Tok.hasLeadingSpace() ? AngleBracketTracker::SpaceBeforeLess
1794                             : AngleBracketTracker::NoSpaceBeforeLess);
1795  AngleBrackets.add(*this, PotentialTemplateName.get(), Tok.getLocation(),
1796                    Priority);
1797}
1798
1799bool Parser::checkPotentialAngleBracketDelimiter(
1800    const AngleBracketTracker::Loc &LAngle, const Token &OpToken) {
1801  // If a comma in an expression context is followed by a type that can be a
1802  // template argument and cannot be an expression, then this is ill-formed,
1803  // but might be intended to be part of a template-id.
1804  if (OpToken.is(tok::comma) && isTypeIdUnambiguously() &&
1805      diagnoseUnknownTemplateId(LAngle.TemplateName, LAngle.LessLoc)) {
1806    AngleBrackets.clear(*this);
1807    return true;
1808  }
1809
1810  // If a context that looks like a template-id is followed by '()', then
1811  // this is ill-formed, but might be intended to be a template-id
1812  // followed by '()'.
1813  if (OpToken.is(tok::greater) && Tok.is(tok::l_paren) &&
1814      NextToken().is(tok::r_paren)) {
1815    Actions.diagnoseExprIntendedAsTemplateName(
1816        getCurScope(), LAngle.TemplateName, LAngle.LessLoc,
1817        OpToken.getLocation());
1818    AngleBrackets.clear(*this);
1819    return true;
1820  }
1821
1822  // After a '>' (etc), we're no longer potentially in a construct that's
1823  // intended to be treated as a template-id.
1824  if (OpToken.is(tok::greater) ||
1825      (getLangOpts().CPlusPlus11 &&
1826       OpToken.isOneOf(tok::greatergreater, tok::greatergreatergreater)))
1827    AngleBrackets.clear(*this);
1828  return false;
1829}
1830