1//===--- ParseTemplate.cpp - Template Parsing -----------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements parsing of C++ templates.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/Parse/Parser.h"
15#include "RAIIObjectsForParser.h"
16#include "clang/AST/ASTConsumer.h"
17#include "clang/AST/DeclTemplate.h"
18#include "clang/Parse/ParseDiagnostic.h"
19#include "clang/Sema/DeclSpec.h"
20#include "clang/Sema/ParsedTemplate.h"
21#include "clang/Sema/Scope.h"
22using namespace clang;
23
24/// \brief Parse a template declaration, explicit instantiation, or
25/// explicit specialization.
26Decl *
27Parser::ParseDeclarationStartingWithTemplate(unsigned Context,
28                                             SourceLocation &DeclEnd,
29                                             AccessSpecifier AS,
30                                             AttributeList *AccessAttrs) {
31  ObjCDeclContextSwitch ObjCDC(*this);
32
33  if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less)) {
34    return ParseExplicitInstantiation(Context,
35                                      SourceLocation(), ConsumeToken(),
36                                      DeclEnd, AS);
37  }
38  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AS,
39                                                  AccessAttrs);
40}
41
42
43
44/// \brief Parse a template declaration or an explicit specialization.
45///
46/// Template declarations include one or more template parameter lists
47/// and either the function or class template declaration. Explicit
48/// specializations contain one or more 'template < >' prefixes
49/// followed by a (possibly templated) declaration. Since the
50/// syntactic form of both features is nearly identical, we parse all
51/// of the template headers together and let semantic analysis sort
52/// the declarations from the explicit specializations.
53///
54///       template-declaration: [C++ temp]
55///         'export'[opt] 'template' '<' template-parameter-list '>' declaration
56///
57///       explicit-specialization: [ C++ temp.expl.spec]
58///         'template' '<' '>' declaration
59Decl *
60Parser::ParseTemplateDeclarationOrSpecialization(unsigned Context,
61                                                 SourceLocation &DeclEnd,
62                                                 AccessSpecifier AS,
63                                                 AttributeList *AccessAttrs) {
64  assert((Tok.is(tok::kw_export) || Tok.is(tok::kw_template)) &&
65         "Token does not start a template declaration.");
66
67  // Enter template-parameter scope.
68  ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
69
70  // Tell the action that names should be checked in the context of
71  // the declaration to come.
72  ParsingDeclRAIIObject
73    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
74
75  // Parse multiple levels of template headers within this template
76  // parameter scope, e.g.,
77  //
78  //   template<typename T>
79  //     template<typename U>
80  //       class A<T>::B { ... };
81  //
82  // We parse multiple levels non-recursively so that we can build a
83  // single data structure containing all of the template parameter
84  // lists to easily differentiate between the case above and:
85  //
86  //   template<typename T>
87  //   class A {
88  //     template<typename U> class B;
89  //   };
90  //
91  // In the first case, the action for declaring A<T>::B receives
92  // both template parameter lists. In the second case, the action for
93  // defining A<T>::B receives just the inner template parameter list
94  // (and retrieves the outer template parameter list from its
95  // context).
96  bool isSpecialization = true;
97  bool LastParamListWasEmpty = false;
98  TemplateParameterLists ParamLists;
99  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
100
101  do {
102    // Consume the 'export', if any.
103    SourceLocation ExportLoc;
104    TryConsumeToken(tok::kw_export, ExportLoc);
105
106    // Consume the 'template', which should be here.
107    SourceLocation TemplateLoc;
108    if (!TryConsumeToken(tok::kw_template, TemplateLoc)) {
109      Diag(Tok.getLocation(), diag::err_expected_template);
110      return nullptr;
111    }
112
113    // Parse the '<' template-parameter-list '>'
114    SourceLocation LAngleLoc, RAngleLoc;
115    SmallVector<Decl*, 4> TemplateParams;
116    if (ParseTemplateParameters(CurTemplateDepthTracker.getDepth(),
117                                TemplateParams, LAngleLoc, RAngleLoc)) {
118      // Skip until the semi-colon or a }.
119      SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
120      TryConsumeToken(tok::semi);
121      return nullptr;
122    }
123
124    ParamLists.push_back(
125      Actions.ActOnTemplateParameterList(CurTemplateDepthTracker.getDepth(),
126                                         ExportLoc,
127                                         TemplateLoc, LAngleLoc,
128                                         TemplateParams.data(),
129                                         TemplateParams.size(), RAngleLoc));
130
131    if (!TemplateParams.empty()) {
132      isSpecialization = false;
133      ++CurTemplateDepthTracker;
134    } else {
135      LastParamListWasEmpty = true;
136    }
137  } while (Tok.is(tok::kw_export) || Tok.is(tok::kw_template));
138
139  // Parse the actual template declaration.
140  return ParseSingleDeclarationAfterTemplate(Context,
141                                             ParsedTemplateInfo(&ParamLists,
142                                                             isSpecialization,
143                                                         LastParamListWasEmpty),
144                                             ParsingTemplateParams,
145                                             DeclEnd, AS, AccessAttrs);
146}
147
148/// \brief Parse a single declaration that declares a template,
149/// template specialization, or explicit instantiation of a template.
150///
151/// \param DeclEnd will receive the source location of the last token
152/// within this declaration.
153///
154/// \param AS the access specifier associated with this
155/// declaration. Will be AS_none for namespace-scope declarations.
156///
157/// \returns the new declaration.
158Decl *
159Parser::ParseSingleDeclarationAfterTemplate(
160                                       unsigned Context,
161                                       const ParsedTemplateInfo &TemplateInfo,
162                                       ParsingDeclRAIIObject &DiagsFromTParams,
163                                       SourceLocation &DeclEnd,
164                                       AccessSpecifier AS,
165                                       AttributeList *AccessAttrs) {
166  assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
167         "Template information required");
168
169  if (Context == Declarator::MemberContext) {
170    // We are parsing a member template.
171    ParseCXXClassMemberDeclaration(AS, AccessAttrs, TemplateInfo,
172                                   &DiagsFromTParams);
173    return nullptr;
174  }
175
176  ParsedAttributesWithRange prefixAttrs(AttrFactory);
177  MaybeParseCXX11Attributes(prefixAttrs);
178
179  if (Tok.is(tok::kw_using))
180    return ParseUsingDirectiveOrDeclaration(Context, TemplateInfo, DeclEnd,
181                                            prefixAttrs);
182
183  // Parse the declaration specifiers, stealing any diagnostics from
184  // the template parameters.
185  ParsingDeclSpec DS(*this, &DiagsFromTParams);
186
187  ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
188                             getDeclSpecContextFromDeclaratorContext(Context));
189
190  if (Tok.is(tok::semi)) {
191    ProhibitAttributes(prefixAttrs);
192    DeclEnd = ConsumeToken();
193    Decl *Decl = Actions.ParsedFreeStandingDeclSpec(
194        getCurScope(), AS, DS,
195        TemplateInfo.TemplateParams ? *TemplateInfo.TemplateParams
196                                    : MultiTemplateParamsArg(),
197        TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation);
198    DS.complete(Decl);
199    return Decl;
200  }
201
202  // Move the attributes from the prefix into the DS.
203  if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation)
204    ProhibitAttributes(prefixAttrs);
205  else
206    DS.takeAttributesFrom(prefixAttrs);
207
208  // Parse the declarator.
209  ParsingDeclarator DeclaratorInfo(*this, DS, (Declarator::TheContext)Context);
210  ParseDeclarator(DeclaratorInfo);
211  // Error parsing the declarator?
212  if (!DeclaratorInfo.hasName()) {
213    // If so, skip until the semi-colon or a }.
214    SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
215    if (Tok.is(tok::semi))
216      ConsumeToken();
217    return nullptr;
218  }
219
220  LateParsedAttrList LateParsedAttrs(true);
221  if (DeclaratorInfo.isFunctionDeclarator())
222    MaybeParseGNUAttributes(DeclaratorInfo, &LateParsedAttrs);
223
224  if (DeclaratorInfo.isFunctionDeclarator() &&
225      isStartOfFunctionDefinition(DeclaratorInfo)) {
226    if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
227      // Recover by ignoring the 'typedef'. This was probably supposed to be
228      // the 'typename' keyword, which we should have already suggested adding
229      // if it's appropriate.
230      Diag(DS.getStorageClassSpecLoc(), diag::err_function_declared_typedef)
231        << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
232      DS.ClearStorageClassSpecs();
233    }
234
235    if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
236      if (DeclaratorInfo.getName().getKind() != UnqualifiedId::IK_TemplateId) {
237        // If the declarator-id is not a template-id, issue a diagnostic and
238        // recover by ignoring the 'template' keyword.
239        Diag(Tok, diag::err_template_defn_explicit_instantiation) << 0;
240        return ParseFunctionDefinition(DeclaratorInfo, ParsedTemplateInfo(),
241                                       &LateParsedAttrs);
242      } else {
243        SourceLocation LAngleLoc
244          = PP.getLocForEndOfToken(TemplateInfo.TemplateLoc);
245        Diag(DeclaratorInfo.getIdentifierLoc(),
246             diag::err_explicit_instantiation_with_definition)
247            << SourceRange(TemplateInfo.TemplateLoc)
248            << FixItHint::CreateInsertion(LAngleLoc, "<>");
249
250        // Recover as if it were an explicit specialization.
251        TemplateParameterLists FakedParamLists;
252        FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
253            0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, nullptr,
254            0, LAngleLoc));
255
256        return ParseFunctionDefinition(
257            DeclaratorInfo, ParsedTemplateInfo(&FakedParamLists,
258                                               /*isSpecialization=*/true,
259                                               /*LastParamListWasEmpty=*/true),
260            &LateParsedAttrs);
261      }
262    }
263    return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo,
264                                   &LateParsedAttrs);
265  }
266
267  // Parse this declaration.
268  Decl *ThisDecl = ParseDeclarationAfterDeclarator(DeclaratorInfo,
269                                                   TemplateInfo);
270
271  if (Tok.is(tok::comma)) {
272    Diag(Tok, diag::err_multiple_template_declarators)
273      << (int)TemplateInfo.Kind;
274    SkipUntil(tok::semi);
275    return ThisDecl;
276  }
277
278  // Eat the semi colon after the declaration.
279  ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
280  if (LateParsedAttrs.size() > 0)
281    ParseLexedAttributeList(LateParsedAttrs, ThisDecl, true, false);
282  DeclaratorInfo.complete(ThisDecl);
283  return ThisDecl;
284}
285
286/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
287/// angle brackets. Depth is the depth of this template-parameter-list, which
288/// is the number of template headers directly enclosing this template header.
289/// TemplateParams is the current list of template parameters we're building.
290/// The template parameter we parse will be added to this list. LAngleLoc and
291/// RAngleLoc will receive the positions of the '<' and '>', respectively,
292/// that enclose this template parameter list.
293///
294/// \returns true if an error occurred, false otherwise.
295bool Parser::ParseTemplateParameters(unsigned Depth,
296                               SmallVectorImpl<Decl*> &TemplateParams,
297                                     SourceLocation &LAngleLoc,
298                                     SourceLocation &RAngleLoc) {
299  // Get the template parameter list.
300  if (!TryConsumeToken(tok::less, LAngleLoc)) {
301    Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
302    return true;
303  }
304
305  // Try to parse the template parameter list.
306  bool Failed = false;
307  if (!Tok.is(tok::greater) && !Tok.is(tok::greatergreater))
308    Failed = ParseTemplateParameterList(Depth, TemplateParams);
309
310  if (Tok.is(tok::greatergreater)) {
311    // No diagnostic required here: a template-parameter-list can only be
312    // followed by a declaration or, for a template template parameter, the
313    // 'class' keyword. Therefore, the second '>' will be diagnosed later.
314    // This matters for elegant diagnosis of:
315    //   template<template<typename>> struct S;
316    Tok.setKind(tok::greater);
317    RAngleLoc = Tok.getLocation();
318    Tok.setLocation(Tok.getLocation().getLocWithOffset(1));
319  } else if (!TryConsumeToken(tok::greater, RAngleLoc) && Failed) {
320    Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
321    return true;
322  }
323  return false;
324}
325
326/// ParseTemplateParameterList - Parse a template parameter list. If
327/// the parsing fails badly (i.e., closing bracket was left out), this
328/// will try to put the token stream in a reasonable position (closing
329/// a statement, etc.) and return false.
330///
331///       template-parameter-list:    [C++ temp]
332///         template-parameter
333///         template-parameter-list ',' template-parameter
334bool
335Parser::ParseTemplateParameterList(unsigned Depth,
336                             SmallVectorImpl<Decl*> &TemplateParams) {
337  while (1) {
338    if (Decl *TmpParam
339          = ParseTemplateParameter(Depth, TemplateParams.size())) {
340      TemplateParams.push_back(TmpParam);
341    } else {
342      // If we failed to parse a template parameter, skip until we find
343      // a comma or closing brace.
344      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
345                StopAtSemi | StopBeforeMatch);
346    }
347
348    // Did we find a comma or the end of the template parameter list?
349    if (Tok.is(tok::comma)) {
350      ConsumeToken();
351    } else if (Tok.is(tok::greater) || Tok.is(tok::greatergreater)) {
352      // Don't consume this... that's done by template parser.
353      break;
354    } else {
355      // Somebody probably forgot to close the template. Skip ahead and
356      // try to get out of the expression. This error is currently
357      // subsumed by whatever goes on in ParseTemplateParameter.
358      Diag(Tok.getLocation(), diag::err_expected_comma_greater);
359      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
360                StopAtSemi | StopBeforeMatch);
361      return false;
362    }
363  }
364  return true;
365}
366
367/// \brief Determine whether the parser is at the start of a template
368/// type parameter.
369bool Parser::isStartOfTemplateTypeParameter() {
370  if (Tok.is(tok::kw_class)) {
371    // "class" may be the start of an elaborated-type-specifier or a
372    // type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
373    switch (NextToken().getKind()) {
374    case tok::equal:
375    case tok::comma:
376    case tok::greater:
377    case tok::greatergreater:
378    case tok::ellipsis:
379      return true;
380
381    case tok::identifier:
382      // This may be either a type-parameter or an elaborated-type-specifier.
383      // We have to look further.
384      break;
385
386    default:
387      return false;
388    }
389
390    switch (GetLookAheadToken(2).getKind()) {
391    case tok::equal:
392    case tok::comma:
393    case tok::greater:
394    case tok::greatergreater:
395      return true;
396
397    default:
398      return false;
399    }
400  }
401
402  if (Tok.isNot(tok::kw_typename))
403    return false;
404
405  // C++ [temp.param]p2:
406  //   There is no semantic difference between class and typename in a
407  //   template-parameter. typename followed by an unqualified-id
408  //   names a template type parameter. typename followed by a
409  //   qualified-id denotes the type in a non-type
410  //   parameter-declaration.
411  Token Next = NextToken();
412
413  // If we have an identifier, skip over it.
414  if (Next.getKind() == tok::identifier)
415    Next = GetLookAheadToken(2);
416
417  switch (Next.getKind()) {
418  case tok::equal:
419  case tok::comma:
420  case tok::greater:
421  case tok::greatergreater:
422  case tok::ellipsis:
423    return true;
424
425  default:
426    return false;
427  }
428}
429
430/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
431///
432///       template-parameter: [C++ temp.param]
433///         type-parameter
434///         parameter-declaration
435///
436///       type-parameter: (see below)
437///         'class' ...[opt] identifier[opt]
438///         'class' identifier[opt] '=' type-id
439///         'typename' ...[opt] identifier[opt]
440///         'typename' identifier[opt] '=' type-id
441///         'template' '<' template-parameter-list '>'
442///               'class' ...[opt] identifier[opt]
443///         'template' '<' template-parameter-list '>' 'class' identifier[opt]
444///               = id-expression
445Decl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {
446  if (isStartOfTemplateTypeParameter())
447    return ParseTypeParameter(Depth, Position);
448
449  if (Tok.is(tok::kw_template))
450    return ParseTemplateTemplateParameter(Depth, Position);
451
452  // If it's none of the above, then it must be a parameter declaration.
453  // NOTE: This will pick up errors in the closure of the template parameter
454  // list (e.g., template < ; Check here to implement >> style closures.
455  return ParseNonTypeTemplateParameter(Depth, Position);
456}
457
458/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
459/// Other kinds of template parameters are parsed in
460/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
461///
462///       type-parameter:     [C++ temp.param]
463///         'class' ...[opt][C++0x] identifier[opt]
464///         'class' identifier[opt] '=' type-id
465///         'typename' ...[opt][C++0x] identifier[opt]
466///         'typename' identifier[opt] '=' type-id
467Decl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
468  assert((Tok.is(tok::kw_class) || Tok.is(tok::kw_typename)) &&
469         "A type-parameter starts with 'class' or 'typename'");
470
471  // Consume the 'class' or 'typename' keyword.
472  bool TypenameKeyword = Tok.is(tok::kw_typename);
473  SourceLocation KeyLoc = ConsumeToken();
474
475  // Grab the ellipsis (if given).
476  SourceLocation EllipsisLoc;
477  if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) {
478    Diag(EllipsisLoc,
479         getLangOpts().CPlusPlus11
480           ? diag::warn_cxx98_compat_variadic_templates
481           : diag::ext_variadic_templates);
482  }
483
484  // Grab the template parameter name (if given)
485  SourceLocation NameLoc;
486  IdentifierInfo *ParamName = nullptr;
487  if (Tok.is(tok::identifier)) {
488    ParamName = Tok.getIdentifierInfo();
489    NameLoc = ConsumeToken();
490  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) ||
491             Tok.is(tok::greater) || Tok.is(tok::greatergreater)) {
492    // Unnamed template parameter. Don't have to do anything here, just
493    // don't consume this token.
494  } else {
495    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
496    return nullptr;
497  }
498
499  // Recover from misplaced ellipsis.
500  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
501  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
502    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
503
504  // Grab a default argument (if available).
505  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
506  // we introduce the type parameter into the local scope.
507  SourceLocation EqualLoc;
508  ParsedType DefaultArg;
509  if (TryConsumeToken(tok::equal, EqualLoc))
510    DefaultArg = ParseTypeName(/*Range=*/nullptr,
511                               Declarator::TemplateTypeArgContext).get();
512
513  return Actions.ActOnTypeParameter(getCurScope(), TypenameKeyword, EllipsisLoc,
514                                    KeyLoc, ParamName, NameLoc, Depth, Position,
515                                    EqualLoc, DefaultArg);
516}
517
518/// ParseTemplateTemplateParameter - Handle the parsing of template
519/// template parameters.
520///
521///       type-parameter:    [C++ temp.param]
522///         'template' '<' template-parameter-list '>' type-parameter-key
523///                  ...[opt] identifier[opt]
524///         'template' '<' template-parameter-list '>' type-parameter-key
525///                  identifier[opt] = id-expression
526///       type-parameter-key:
527///         'class'
528///         'typename'       [C++1z]
529Decl *
530Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
531  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
532
533  // Handle the template <...> part.
534  SourceLocation TemplateLoc = ConsumeToken();
535  SmallVector<Decl*,8> TemplateParams;
536  SourceLocation LAngleLoc, RAngleLoc;
537  {
538    ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
539    if (ParseTemplateParameters(Depth + 1, TemplateParams, LAngleLoc,
540                               RAngleLoc)) {
541      return nullptr;
542    }
543  }
544
545  // Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
546  // Generate a meaningful error if the user forgot to put class before the
547  // identifier, comma, or greater. Provide a fixit if the identifier, comma,
548  // or greater appear immediately or after 'struct'. In the latter case,
549  // replace the keyword with 'class'.
550  if (!TryConsumeToken(tok::kw_class)) {
551    bool Replace = Tok.is(tok::kw_typename) || Tok.is(tok::kw_struct);
552    const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
553    if (Tok.is(tok::kw_typename)) {
554      Diag(Tok.getLocation(),
555           getLangOpts().CPlusPlus1z
556               ? diag::warn_cxx1y_compat_template_template_param_typename
557               : diag::ext_template_template_param_typename)
558        << (!getLangOpts().CPlusPlus1z
559                ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
560                : FixItHint());
561    } else if (Next.is(tok::identifier) || Next.is(tok::comma) ||
562               Next.is(tok::greater) || Next.is(tok::greatergreater) ||
563               Next.is(tok::ellipsis)) {
564      Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
565        << (Replace ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
566                    : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
567    } else
568      Diag(Tok.getLocation(), diag::err_class_on_template_template_param);
569
570    if (Replace)
571      ConsumeToken();
572  }
573
574  // Parse the ellipsis, if given.
575  SourceLocation EllipsisLoc;
576  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
577    Diag(EllipsisLoc,
578         getLangOpts().CPlusPlus11
579           ? diag::warn_cxx98_compat_variadic_templates
580           : diag::ext_variadic_templates);
581
582  // Get the identifier, if given.
583  SourceLocation NameLoc;
584  IdentifierInfo *ParamName = nullptr;
585  if (Tok.is(tok::identifier)) {
586    ParamName = Tok.getIdentifierInfo();
587    NameLoc = ConsumeToken();
588  } else if (Tok.is(tok::equal) || Tok.is(tok::comma) ||
589             Tok.is(tok::greater) || Tok.is(tok::greatergreater)) {
590    // Unnamed template parameter. Don't have to do anything here, just
591    // don't consume this token.
592  } else {
593    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
594    return nullptr;
595  }
596
597  // Recover from misplaced ellipsis.
598  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
599  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
600    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
601
602  TemplateParameterList *ParamList =
603    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
604                                       TemplateLoc, LAngleLoc,
605                                       TemplateParams.data(),
606                                       TemplateParams.size(),
607                                       RAngleLoc);
608
609  // Grab a default argument (if available).
610  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
611  // we introduce the template parameter into the local scope.
612  SourceLocation EqualLoc;
613  ParsedTemplateArgument DefaultArg;
614  if (TryConsumeToken(tok::equal, EqualLoc)) {
615    DefaultArg = ParseTemplateTemplateArgument();
616    if (DefaultArg.isInvalid()) {
617      Diag(Tok.getLocation(),
618           diag::err_default_template_template_parameter_not_template);
619      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
620                StopAtSemi | StopBeforeMatch);
621    }
622  }
623
624  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
625                                                ParamList, EllipsisLoc,
626                                                ParamName, NameLoc, Depth,
627                                                Position, EqualLoc, DefaultArg);
628}
629
630/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
631/// template parameters (e.g., in "template<int Size> class array;").
632///
633///       template-parameter:
634///         ...
635///         parameter-declaration
636Decl *
637Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
638  // Parse the declaration-specifiers (i.e., the type).
639  // FIXME: The type should probably be restricted in some way... Not all
640  // declarators (parts of declarators?) are accepted for parameters.
641  DeclSpec DS(AttrFactory);
642  ParseDeclarationSpecifiers(DS);
643
644  // Parse this as a typename.
645  Declarator ParamDecl(DS, Declarator::TemplateParamContext);
646  ParseDeclarator(ParamDecl);
647  if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
648    Diag(Tok.getLocation(), diag::err_expected_template_parameter);
649    return nullptr;
650  }
651
652  // Recover from misplaced ellipsis.
653  SourceLocation EllipsisLoc;
654  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
655    DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, ParamDecl);
656
657  // If there is a default value, parse it.
658  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
659  // we introduce the template parameter into the local scope.
660  SourceLocation EqualLoc;
661  ExprResult DefaultArg;
662  if (TryConsumeToken(tok::equal, EqualLoc)) {
663    // C++ [temp.param]p15:
664    //   When parsing a default template-argument for a non-type
665    //   template-parameter, the first non-nested > is taken as the
666    //   end of the template-parameter-list rather than a greater-than
667    //   operator.
668    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
669    EnterExpressionEvaluationContext Unevaluated(Actions, Sema::Unevaluated);
670
671    DefaultArg = ParseAssignmentExpression();
672    if (DefaultArg.isInvalid())
673      SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
674  }
675
676  // Create the parameter.
677  return Actions.ActOnNonTypeTemplateParameter(getCurScope(), ParamDecl,
678                                               Depth, Position, EqualLoc,
679                                               DefaultArg.get());
680}
681
682void Parser::DiagnoseMisplacedEllipsis(SourceLocation EllipsisLoc,
683                                       SourceLocation CorrectLoc,
684                                       bool AlreadyHasEllipsis,
685                                       bool IdentifierHasName) {
686  FixItHint Insertion;
687  if (!AlreadyHasEllipsis)
688    Insertion = FixItHint::CreateInsertion(CorrectLoc, "...");
689  Diag(EllipsisLoc, diag::err_misplaced_ellipsis_in_declaration)
690      << FixItHint::CreateRemoval(EllipsisLoc) << Insertion
691      << !IdentifierHasName;
692}
693
694void Parser::DiagnoseMisplacedEllipsisInDeclarator(SourceLocation EllipsisLoc,
695                                                   Declarator &D) {
696  assert(EllipsisLoc.isValid());
697  bool AlreadyHasEllipsis = D.getEllipsisLoc().isValid();
698  if (!AlreadyHasEllipsis)
699    D.setEllipsisLoc(EllipsisLoc);
700  DiagnoseMisplacedEllipsis(EllipsisLoc, D.getIdentifierLoc(),
701                            AlreadyHasEllipsis, D.hasName());
702}
703
704/// \brief Parses a '>' at the end of a template list.
705///
706/// If this function encounters '>>', '>>>', '>=', or '>>=', it tries
707/// to determine if these tokens were supposed to be a '>' followed by
708/// '>', '>>', '>=', or '>='. It emits an appropriate diagnostic if necessary.
709///
710/// \param RAngleLoc the location of the consumed '>'.
711///
712/// \param ConsumeLastToken if true, the '>' is not consumed.
713///
714/// \returns true, if current token does not start with '>', false otherwise.
715bool Parser::ParseGreaterThanInTemplateList(SourceLocation &RAngleLoc,
716                                            bool ConsumeLastToken) {
717  // What will be left once we've consumed the '>'.
718  tok::TokenKind RemainingToken;
719  const char *ReplacementStr = "> >";
720
721  switch (Tok.getKind()) {
722  default:
723    Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
724    return true;
725
726  case tok::greater:
727    // Determine the location of the '>' token. Only consume this token
728    // if the caller asked us to.
729    RAngleLoc = Tok.getLocation();
730    if (ConsumeLastToken)
731      ConsumeToken();
732    return false;
733
734  case tok::greatergreater:
735    RemainingToken = tok::greater;
736    break;
737
738  case tok::greatergreatergreater:
739    RemainingToken = tok::greatergreater;
740    break;
741
742  case tok::greaterequal:
743    RemainingToken = tok::equal;
744    ReplacementStr = "> =";
745    break;
746
747  case tok::greatergreaterequal:
748    RemainingToken = tok::greaterequal;
749    break;
750  }
751
752  // This template-id is terminated by a token which starts with a '>'. Outside
753  // C++11, this is now error recovery, and in C++11, this is error recovery if
754  // the token isn't '>>' or '>>>'.
755  // '>>>' is for CUDA, where this sequence of characters is parsed into
756  // tok::greatergreatergreater, rather than two separate tokens.
757
758  RAngleLoc = Tok.getLocation();
759
760  // The source range of the '>>' or '>=' at the start of the token.
761  CharSourceRange ReplacementRange =
762      CharSourceRange::getCharRange(RAngleLoc,
763          Lexer::AdvanceToTokenCharacter(RAngleLoc, 2, PP.getSourceManager(),
764                                         getLangOpts()));
765
766  // A hint to put a space between the '>>'s. In order to make the hint as
767  // clear as possible, we include the characters either side of the space in
768  // the replacement, rather than just inserting a space at SecondCharLoc.
769  FixItHint Hint1 = FixItHint::CreateReplacement(ReplacementRange,
770                                                 ReplacementStr);
771
772  // A hint to put another space after the token, if it would otherwise be
773  // lexed differently.
774  FixItHint Hint2;
775  Token Next = NextToken();
776  if ((RemainingToken == tok::greater ||
777       RemainingToken == tok::greatergreater) &&
778      (Next.is(tok::greater) || Next.is(tok::greatergreater) ||
779       Next.is(tok::greatergreatergreater) || Next.is(tok::equal) ||
780       Next.is(tok::greaterequal) || Next.is(tok::greatergreaterequal) ||
781       Next.is(tok::equalequal)) &&
782      areTokensAdjacent(Tok, Next))
783    Hint2 = FixItHint::CreateInsertion(Next.getLocation(), " ");
784
785  unsigned DiagId = diag::err_two_right_angle_brackets_need_space;
786  if (getLangOpts().CPlusPlus11 &&
787      (Tok.is(tok::greatergreater) || Tok.is(tok::greatergreatergreater)))
788    DiagId = diag::warn_cxx98_compat_two_right_angle_brackets;
789  else if (Tok.is(tok::greaterequal))
790    DiagId = diag::err_right_angle_bracket_equal_needs_space;
791  Diag(Tok.getLocation(), DiagId) << Hint1 << Hint2;
792
793  // Strip the initial '>' from the token.
794  if (RemainingToken == tok::equal && Next.is(tok::equal) &&
795      areTokensAdjacent(Tok, Next)) {
796    // Join two adjacent '=' tokens into one, for cases like:
797    //   void (*p)() = f<int>;
798    //   return f<int>==p;
799    ConsumeToken();
800    Tok.setKind(tok::equalequal);
801    Tok.setLength(Tok.getLength() + 1);
802  } else {
803    Tok.setKind(RemainingToken);
804    Tok.setLength(Tok.getLength() - 1);
805  }
806  Tok.setLocation(Lexer::AdvanceToTokenCharacter(RAngleLoc, 1,
807                                                 PP.getSourceManager(),
808                                                 getLangOpts()));
809
810  if (!ConsumeLastToken) {
811    // Since we're not supposed to consume the '>' token, we need to push
812    // this token and revert the current token back to the '>'.
813    PP.EnterToken(Tok);
814    Tok.setKind(tok::greater);
815    Tok.setLength(1);
816    Tok.setLocation(RAngleLoc);
817  }
818  return false;
819}
820
821
822/// \brief Parses a template-id that after the template name has
823/// already been parsed.
824///
825/// This routine takes care of parsing the enclosed template argument
826/// list ('<' template-parameter-list [opt] '>') and placing the
827/// results into a form that can be transferred to semantic analysis.
828///
829/// \param Template the template declaration produced by isTemplateName
830///
831/// \param TemplateNameLoc the source location of the template name
832///
833/// \param SS if non-NULL, the nested-name-specifier preceding the
834/// template name.
835///
836/// \param ConsumeLastToken if true, then we will consume the last
837/// token that forms the template-id. Otherwise, we will leave the
838/// last token in the stream (e.g., so that it can be replaced with an
839/// annotation token).
840bool
841Parser::ParseTemplateIdAfterTemplateName(TemplateTy Template,
842                                         SourceLocation TemplateNameLoc,
843                                         const CXXScopeSpec &SS,
844                                         bool ConsumeLastToken,
845                                         SourceLocation &LAngleLoc,
846                                         TemplateArgList &TemplateArgs,
847                                         SourceLocation &RAngleLoc) {
848  assert(Tok.is(tok::less) && "Must have already parsed the template-name");
849
850  // Consume the '<'.
851  LAngleLoc = ConsumeToken();
852
853  // Parse the optional template-argument-list.
854  bool Invalid = false;
855  {
856    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
857    if (Tok.isNot(tok::greater) && Tok.isNot(tok::greatergreater))
858      Invalid = ParseTemplateArgumentList(TemplateArgs);
859
860    if (Invalid) {
861      // Try to find the closing '>'.
862      if (ConsumeLastToken)
863        SkipUntil(tok::greater, StopAtSemi);
864      else
865        SkipUntil(tok::greater, StopAtSemi | StopBeforeMatch);
866      return true;
867    }
868  }
869
870  return ParseGreaterThanInTemplateList(RAngleLoc, ConsumeLastToken);
871}
872
873/// \brief Replace the tokens that form a simple-template-id with an
874/// annotation token containing the complete template-id.
875///
876/// The first token in the stream must be the name of a template that
877/// is followed by a '<'. This routine will parse the complete
878/// simple-template-id and replace the tokens with a single annotation
879/// token with one of two different kinds: if the template-id names a
880/// type (and \p AllowTypeAnnotation is true), the annotation token is
881/// a type annotation that includes the optional nested-name-specifier
882/// (\p SS). Otherwise, the annotation token is a template-id
883/// annotation that does not include the optional
884/// nested-name-specifier.
885///
886/// \param Template  the declaration of the template named by the first
887/// token (an identifier), as returned from \c Action::isTemplateName().
888///
889/// \param TNK the kind of template that \p Template
890/// refers to, as returned from \c Action::isTemplateName().
891///
892/// \param SS if non-NULL, the nested-name-specifier that precedes
893/// this template name.
894///
895/// \param TemplateKWLoc if valid, specifies that this template-id
896/// annotation was preceded by the 'template' keyword and gives the
897/// location of that keyword. If invalid (the default), then this
898/// template-id was not preceded by a 'template' keyword.
899///
900/// \param AllowTypeAnnotation if true (the default), then a
901/// simple-template-id that refers to a class template, template
902/// template parameter, or other template that produces a type will be
903/// replaced with a type annotation token. Otherwise, the
904/// simple-template-id is always replaced with a template-id
905/// annotation token.
906///
907/// If an unrecoverable parse error occurs and no annotation token can be
908/// formed, this function returns true.
909///
910bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
911                                     CXXScopeSpec &SS,
912                                     SourceLocation TemplateKWLoc,
913                                     UnqualifiedId &TemplateName,
914                                     bool AllowTypeAnnotation) {
915  assert(getLangOpts().CPlusPlus && "Can only annotate template-ids in C++");
916  assert(Template && Tok.is(tok::less) &&
917         "Parser isn't at the beginning of a template-id");
918
919  // Consume the template-name.
920  SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();
921
922  // Parse the enclosed template argument list.
923  SourceLocation LAngleLoc, RAngleLoc;
924  TemplateArgList TemplateArgs;
925  bool Invalid = ParseTemplateIdAfterTemplateName(Template,
926                                                  TemplateNameLoc,
927                                                  SS, false, LAngleLoc,
928                                                  TemplateArgs,
929                                                  RAngleLoc);
930
931  if (Invalid) {
932    // If we failed to parse the template ID but skipped ahead to a >, we're not
933    // going to be able to form a token annotation.  Eat the '>' if present.
934    TryConsumeToken(tok::greater);
935    return true;
936  }
937
938  ASTTemplateArgsPtr TemplateArgsPtr(TemplateArgs);
939
940  // Build the annotation token.
941  if (TNK == TNK_Type_template && AllowTypeAnnotation) {
942    TypeResult Type
943      = Actions.ActOnTemplateIdType(SS, TemplateKWLoc,
944                                    Template, TemplateNameLoc,
945                                    LAngleLoc, TemplateArgsPtr, RAngleLoc);
946    if (Type.isInvalid()) {
947      // If we failed to parse the template ID but skipped ahead to a >, we're not
948      // going to be able to form a token annotation.  Eat the '>' if present.
949      TryConsumeToken(tok::greater);
950      return true;
951    }
952
953    Tok.setKind(tok::annot_typename);
954    setTypeAnnotation(Tok, Type.get());
955    if (SS.isNotEmpty())
956      Tok.setLocation(SS.getBeginLoc());
957    else if (TemplateKWLoc.isValid())
958      Tok.setLocation(TemplateKWLoc);
959    else
960      Tok.setLocation(TemplateNameLoc);
961  } else {
962    // Build a template-id annotation token that can be processed
963    // later.
964    Tok.setKind(tok::annot_template_id);
965    TemplateIdAnnotation *TemplateId
966      = TemplateIdAnnotation::Allocate(TemplateArgs.size(), TemplateIds);
967    TemplateId->TemplateNameLoc = TemplateNameLoc;
968    if (TemplateName.getKind() == UnqualifiedId::IK_Identifier) {
969      TemplateId->Name = TemplateName.Identifier;
970      TemplateId->Operator = OO_None;
971    } else {
972      TemplateId->Name = nullptr;
973      TemplateId->Operator = TemplateName.OperatorFunctionId.Operator;
974    }
975    TemplateId->SS = SS;
976    TemplateId->TemplateKWLoc = TemplateKWLoc;
977    TemplateId->Template = Template;
978    TemplateId->Kind = TNK;
979    TemplateId->LAngleLoc = LAngleLoc;
980    TemplateId->RAngleLoc = RAngleLoc;
981    ParsedTemplateArgument *Args = TemplateId->getTemplateArgs();
982    for (unsigned Arg = 0, ArgEnd = TemplateArgs.size(); Arg != ArgEnd; ++Arg)
983      Args[Arg] = ParsedTemplateArgument(TemplateArgs[Arg]);
984    Tok.setAnnotationValue(TemplateId);
985    if (TemplateKWLoc.isValid())
986      Tok.setLocation(TemplateKWLoc);
987    else
988      Tok.setLocation(TemplateNameLoc);
989  }
990
991  // Common fields for the annotation token
992  Tok.setAnnotationEndLoc(RAngleLoc);
993
994  // In case the tokens were cached, have Preprocessor replace them with the
995  // annotation token.
996  PP.AnnotateCachedTokens(Tok);
997  return false;
998}
999
1000/// \brief Replaces a template-id annotation token with a type
1001/// annotation token.
1002///
1003/// If there was a failure when forming the type from the template-id,
1004/// a type annotation token will still be created, but will have a
1005/// NULL type pointer to signify an error.
1006void Parser::AnnotateTemplateIdTokenAsType() {
1007  assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens");
1008
1009  TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
1010  assert((TemplateId->Kind == TNK_Type_template ||
1011          TemplateId->Kind == TNK_Dependent_template_name) &&
1012         "Only works for type and dependent templates");
1013
1014  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
1015                                     TemplateId->NumArgs);
1016
1017  TypeResult Type
1018    = Actions.ActOnTemplateIdType(TemplateId->SS,
1019                                  TemplateId->TemplateKWLoc,
1020                                  TemplateId->Template,
1021                                  TemplateId->TemplateNameLoc,
1022                                  TemplateId->LAngleLoc,
1023                                  TemplateArgsPtr,
1024                                  TemplateId->RAngleLoc);
1025  // Create the new "type" annotation token.
1026  Tok.setKind(tok::annot_typename);
1027  setTypeAnnotation(Tok, Type.isInvalid() ? ParsedType() : Type.get());
1028  if (TemplateId->SS.isNotEmpty()) // it was a C++ qualified type name.
1029    Tok.setLocation(TemplateId->SS.getBeginLoc());
1030  // End location stays the same
1031
1032  // Replace the template-id annotation token, and possible the scope-specifier
1033  // that precedes it, with the typename annotation token.
1034  PP.AnnotateCachedTokens(Tok);
1035}
1036
1037/// \brief Determine whether the given token can end a template argument.
1038static bool isEndOfTemplateArgument(Token Tok) {
1039  return Tok.is(tok::comma) || Tok.is(tok::greater) ||
1040         Tok.is(tok::greatergreater);
1041}
1042
1043/// \brief Parse a C++ template template argument.
1044ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
1045  if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
1046      !Tok.is(tok::annot_cxxscope))
1047    return ParsedTemplateArgument();
1048
1049  // C++0x [temp.arg.template]p1:
1050  //   A template-argument for a template template-parameter shall be the name
1051  //   of a class template or an alias template, expressed as id-expression.
1052  //
1053  // We parse an id-expression that refers to a class template or alias
1054  // template. The grammar we parse is:
1055  //
1056  //   nested-name-specifier[opt] template[opt] identifier ...[opt]
1057  //
1058  // followed by a token that terminates a template argument, such as ',',
1059  // '>', or (in some cases) '>>'.
1060  CXXScopeSpec SS; // nested-name-specifier, if present
1061  ParseOptionalCXXScopeSpecifier(SS, ParsedType(),
1062                                 /*EnteringContext=*/false);
1063
1064  ParsedTemplateArgument Result;
1065  SourceLocation EllipsisLoc;
1066  if (SS.isSet() && Tok.is(tok::kw_template)) {
1067    // Parse the optional 'template' keyword following the
1068    // nested-name-specifier.
1069    SourceLocation TemplateKWLoc = ConsumeToken();
1070
1071    if (Tok.is(tok::identifier)) {
1072      // We appear to have a dependent template name.
1073      UnqualifiedId Name;
1074      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1075      ConsumeToken(); // the identifier
1076
1077      TryConsumeToken(tok::ellipsis, EllipsisLoc);
1078
1079      // If the next token signals the end of a template argument,
1080      // then we have a dependent template name that could be a template
1081      // template argument.
1082      TemplateTy Template;
1083      if (isEndOfTemplateArgument(Tok) &&
1084          Actions.ActOnDependentTemplateName(getCurScope(),
1085                                             SS, TemplateKWLoc, Name,
1086                                             /*ObjectType=*/ ParsedType(),
1087                                             /*EnteringContext=*/false,
1088                                             Template))
1089        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1090    }
1091  } else if (Tok.is(tok::identifier)) {
1092    // We may have a (non-dependent) template name.
1093    TemplateTy Template;
1094    UnqualifiedId Name;
1095    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1096    ConsumeToken(); // the identifier
1097
1098    TryConsumeToken(tok::ellipsis, EllipsisLoc);
1099
1100    if (isEndOfTemplateArgument(Tok)) {
1101      bool MemberOfUnknownSpecialization;
1102      TemplateNameKind TNK = Actions.isTemplateName(getCurScope(), SS,
1103                                               /*hasTemplateKeyword=*/false,
1104                                                    Name,
1105                                               /*ObjectType=*/ ParsedType(),
1106                                                    /*EnteringContext=*/false,
1107                                                    Template,
1108                                                MemberOfUnknownSpecialization);
1109      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
1110        // We have an id-expression that refers to a class template or
1111        // (C++0x) alias template.
1112        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1113      }
1114    }
1115  }
1116
1117  // If this is a pack expansion, build it as such.
1118  if (EllipsisLoc.isValid() && !Result.isInvalid())
1119    Result = Actions.ActOnPackExpansion(Result, EllipsisLoc);
1120
1121  return Result;
1122}
1123
1124/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
1125///
1126///       template-argument: [C++ 14.2]
1127///         constant-expression
1128///         type-id
1129///         id-expression
1130ParsedTemplateArgument Parser::ParseTemplateArgument() {
1131  // C++ [temp.arg]p2:
1132  //   In a template-argument, an ambiguity between a type-id and an
1133  //   expression is resolved to a type-id, regardless of the form of
1134  //   the corresponding template-parameter.
1135  //
1136  // Therefore, we initially try to parse a type-id.
1137  if (isCXXTypeId(TypeIdAsTemplateArgument)) {
1138    SourceLocation Loc = Tok.getLocation();
1139    TypeResult TypeArg = ParseTypeName(/*Range=*/nullptr,
1140                                       Declarator::TemplateTypeArgContext);
1141    if (TypeArg.isInvalid())
1142      return ParsedTemplateArgument();
1143
1144    return ParsedTemplateArgument(ParsedTemplateArgument::Type,
1145                                  TypeArg.get().getAsOpaquePtr(),
1146                                  Loc);
1147  }
1148
1149  // Try to parse a template template argument.
1150  {
1151    TentativeParsingAction TPA(*this);
1152
1153    ParsedTemplateArgument TemplateTemplateArgument
1154      = ParseTemplateTemplateArgument();
1155    if (!TemplateTemplateArgument.isInvalid()) {
1156      TPA.Commit();
1157      return TemplateTemplateArgument;
1158    }
1159
1160    // Revert this tentative parse to parse a non-type template argument.
1161    TPA.Revert();
1162  }
1163
1164  // Parse a non-type template argument.
1165  SourceLocation Loc = Tok.getLocation();
1166  ExprResult ExprArg = ParseConstantExpression(MaybeTypeCast);
1167  if (ExprArg.isInvalid() || !ExprArg.get())
1168    return ParsedTemplateArgument();
1169
1170  return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
1171                                ExprArg.get(), Loc);
1172}
1173
1174/// \brief Determine whether the current tokens can only be parsed as a
1175/// template argument list (starting with the '<') and never as a '<'
1176/// expression.
1177bool Parser::IsTemplateArgumentList(unsigned Skip) {
1178  struct AlwaysRevertAction : TentativeParsingAction {
1179    AlwaysRevertAction(Parser &P) : TentativeParsingAction(P) { }
1180    ~AlwaysRevertAction() { Revert(); }
1181  } Tentative(*this);
1182
1183  while (Skip) {
1184    ConsumeToken();
1185    --Skip;
1186  }
1187
1188  // '<'
1189  if (!TryConsumeToken(tok::less))
1190    return false;
1191
1192  // An empty template argument list.
1193  if (Tok.is(tok::greater))
1194    return true;
1195
1196  // See whether we have declaration specifiers, which indicate a type.
1197  while (isCXXDeclarationSpecifier() == TPResult::True)
1198    ConsumeToken();
1199
1200  // If we have a '>' or a ',' then this is a template argument list.
1201  return Tok.is(tok::greater) || Tok.is(tok::comma);
1202}
1203
1204/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1205/// (C++ [temp.names]). Returns true if there was an error.
1206///
1207///       template-argument-list: [C++ 14.2]
1208///         template-argument
1209///         template-argument-list ',' template-argument
1210bool
1211Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {
1212  // Template argument lists are constant-evaluation contexts.
1213  EnterExpressionEvaluationContext EvalContext(Actions,Sema::ConstantEvaluated);
1214  ColonProtectionRAIIObject ColonProtection(*this, false);
1215
1216  do {
1217    ParsedTemplateArgument Arg = ParseTemplateArgument();
1218    SourceLocation EllipsisLoc;
1219    if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
1220      Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);
1221
1222    if (Arg.isInvalid()) {
1223      SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
1224      return true;
1225    }
1226
1227    // Save this template argument.
1228    TemplateArgs.push_back(Arg);
1229
1230    // If the next token is a comma, consume it and keep reading
1231    // arguments.
1232  } while (TryConsumeToken(tok::comma));
1233
1234  return false;
1235}
1236
1237/// \brief Parse a C++ explicit template instantiation
1238/// (C++ [temp.explicit]).
1239///
1240///       explicit-instantiation:
1241///         'extern' [opt] 'template' declaration
1242///
1243/// Note that the 'extern' is a GNU extension and C++11 feature.
1244Decl *Parser::ParseExplicitInstantiation(unsigned Context,
1245                                         SourceLocation ExternLoc,
1246                                         SourceLocation TemplateLoc,
1247                                         SourceLocation &DeclEnd,
1248                                         AccessSpecifier AS) {
1249  // This isn't really required here.
1250  ParsingDeclRAIIObject
1251    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
1252
1253  return ParseSingleDeclarationAfterTemplate(Context,
1254                                             ParsedTemplateInfo(ExternLoc,
1255                                                                TemplateLoc),
1256                                             ParsingTemplateParams,
1257                                             DeclEnd, AS);
1258}
1259
1260SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
1261  if (TemplateParams)
1262    return getTemplateParamsRange(TemplateParams->data(),
1263                                  TemplateParams->size());
1264
1265  SourceRange R(TemplateLoc);
1266  if (ExternLoc.isValid())
1267    R.setBegin(ExternLoc);
1268  return R;
1269}
1270
1271void Parser::LateTemplateParserCallback(void *P, LateParsedTemplate &LPT) {
1272  ((Parser *)P)->ParseLateTemplatedFuncDef(LPT);
1273}
1274
1275/// \brief Late parse a C++ function template in Microsoft mode.
1276void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
1277  if (!LPT.D)
1278     return;
1279
1280  // Get the FunctionDecl.
1281  FunctionDecl *FunD = LPT.D->getAsFunction();
1282  // Track template parameter depth.
1283  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
1284
1285  // To restore the context after late parsing.
1286  Sema::ContextRAII GlobalSavedContext(Actions, Actions.CurContext);
1287
1288  SmallVector<ParseScope*, 4> TemplateParamScopeStack;
1289
1290  // Get the list of DeclContexts to reenter.
1291  SmallVector<DeclContext*, 4> DeclContextsToReenter;
1292  DeclContext *DD = FunD;
1293  while (DD && !DD->isTranslationUnit()) {
1294    DeclContextsToReenter.push_back(DD);
1295    DD = DD->getLexicalParent();
1296  }
1297
1298  // Reenter template scopes from outermost to innermost.
1299  SmallVectorImpl<DeclContext *>::reverse_iterator II =
1300      DeclContextsToReenter.rbegin();
1301  for (; II != DeclContextsToReenter.rend(); ++II) {
1302    TemplateParamScopeStack.push_back(new ParseScope(this,
1303          Scope::TemplateParamScope));
1304    unsigned NumParamLists =
1305      Actions.ActOnReenterTemplateScope(getCurScope(), cast<Decl>(*II));
1306    CurTemplateDepthTracker.addDepth(NumParamLists);
1307    if (*II != FunD) {
1308      TemplateParamScopeStack.push_back(new ParseScope(this, Scope::DeclScope));
1309      Actions.PushDeclContext(Actions.getCurScope(), *II);
1310    }
1311  }
1312
1313  assert(!LPT.Toks.empty() && "Empty body!");
1314
1315  // Append the current token at the end of the new token stream so that it
1316  // doesn't get lost.
1317  LPT.Toks.push_back(Tok);
1318  PP.EnterTokenStream(LPT.Toks.data(), LPT.Toks.size(), true, false);
1319
1320  // Consume the previously pushed token.
1321  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
1322  assert((Tok.is(tok::l_brace) || Tok.is(tok::colon) || Tok.is(tok::kw_try))
1323         && "Inline method not starting with '{', ':' or 'try'");
1324
1325  // Parse the method body. Function body parsing code is similar enough
1326  // to be re-used for method bodies as well.
1327  ParseScope FnScope(this, Scope::FnScope|Scope::DeclScope);
1328
1329  // Recreate the containing function DeclContext.
1330  Sema::ContextRAII FunctionSavedContext(Actions, Actions.getContainingDC(FunD));
1331
1332  Actions.ActOnStartOfFunctionDef(getCurScope(), FunD);
1333
1334  if (Tok.is(tok::kw_try)) {
1335    ParseFunctionTryBlock(LPT.D, FnScope);
1336  } else {
1337    if (Tok.is(tok::colon))
1338      ParseConstructorInitializer(LPT.D);
1339    else
1340      Actions.ActOnDefaultCtorInitializers(LPT.D);
1341
1342    if (Tok.is(tok::l_brace)) {
1343      assert((!isa<FunctionTemplateDecl>(LPT.D) ||
1344              cast<FunctionTemplateDecl>(LPT.D)
1345                      ->getTemplateParameters()
1346                      ->getDepth() == TemplateParameterDepth - 1) &&
1347             "TemplateParameterDepth should be greater than the depth of "
1348             "current template being instantiated!");
1349      ParseFunctionStatementBody(LPT.D, FnScope);
1350      Actions.UnmarkAsLateParsedTemplate(FunD);
1351    } else
1352      Actions.ActOnFinishFunctionBody(LPT.D, nullptr);
1353  }
1354
1355  // Exit scopes.
1356  FnScope.Exit();
1357  SmallVectorImpl<ParseScope *>::reverse_iterator I =
1358   TemplateParamScopeStack.rbegin();
1359  for (; I != TemplateParamScopeStack.rend(); ++I)
1360    delete *I;
1361}
1362
1363/// \brief Lex a delayed template function for late parsing.
1364void Parser::LexTemplateFunctionForLateParsing(CachedTokens &Toks) {
1365  tok::TokenKind kind = Tok.getKind();
1366  if (!ConsumeAndStoreFunctionPrologue(Toks)) {
1367    // Consume everything up to (and including) the matching right brace.
1368    ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1369  }
1370
1371  // If we're in a function-try-block, we need to store all the catch blocks.
1372  if (kind == tok::kw_try) {
1373    while (Tok.is(tok::kw_catch)) {
1374      ConsumeAndStoreUntil(tok::l_brace, Toks, /*StopAtSemi=*/false);
1375      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1376    }
1377  }
1378}
1379