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/ASTContext.h"
18#include "clang/AST/DeclTemplate.h"
19#include "clang/Parse/ParseDiagnostic.h"
20#include "clang/Sema/DeclSpec.h"
21#include "clang/Sema/ParsedTemplate.h"
22#include "clang/Sema/Scope.h"
23using namespace clang;
24
25/// \brief Parse a template declaration, explicit instantiation, or
26/// explicit specialization.
27Decl *
28Parser::ParseDeclarationStartingWithTemplate(unsigned Context,
29                                             SourceLocation &DeclEnd,
30                                             AccessSpecifier AS,
31                                             AttributeList *AccessAttrs) {
32  ObjCDeclContextSwitch ObjCDC(*this);
33
34  if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less)) {
35    return ParseExplicitInstantiation(Context,
36                                      SourceLocation(), ConsumeToken(),
37                                      DeclEnd, AS);
38  }
39  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AS,
40                                                  AccessAttrs);
41}
42
43
44
45/// \brief Parse a template declaration or an explicit specialization.
46///
47/// Template declarations include one or more template parameter lists
48/// and either the function or class template declaration. Explicit
49/// specializations contain one or more 'template < >' prefixes
50/// followed by a (possibly templated) declaration. Since the
51/// syntactic form of both features is nearly identical, we parse all
52/// of the template headers together and let semantic analysis sort
53/// the declarations from the explicit specializations.
54///
55///       template-declaration: [C++ temp]
56///         'export'[opt] 'template' '<' template-parameter-list '>' declaration
57///
58///       explicit-specialization: [ C++ temp.expl.spec]
59///         'template' '<' '>' declaration
60Decl *
61Parser::ParseTemplateDeclarationOrSpecialization(unsigned Context,
62                                                 SourceLocation &DeclEnd,
63                                                 AccessSpecifier AS,
64                                                 AttributeList *AccessAttrs) {
65  assert(Tok.isOneOf(tok::kw_export, tok::kw_template) &&
66         "Token does not start a template declaration.");
67
68  // Enter template-parameter scope.
69  ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
70
71  // Tell the action that names should be checked in the context of
72  // the declaration to come.
73  ParsingDeclRAIIObject
74    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
75
76  // Parse multiple levels of template headers within this template
77  // parameter scope, e.g.,
78  //
79  //   template<typename T>
80  //     template<typename U>
81  //       class A<T>::B { ... };
82  //
83  // We parse multiple levels non-recursively so that we can build a
84  // single data structure containing all of the template parameter
85  // lists to easily differentiate between the case above and:
86  //
87  //   template<typename T>
88  //   class A {
89  //     template<typename U> class B;
90  //   };
91  //
92  // In the first case, the action for declaring A<T>::B receives
93  // both template parameter lists. In the second case, the action for
94  // defining A<T>::B receives just the inner template parameter list
95  // (and retrieves the outer template parameter list from its
96  // context).
97  bool isSpecialization = true;
98  bool LastParamListWasEmpty = false;
99  TemplateParameterLists ParamLists;
100  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
101
102  do {
103    // Consume the 'export', if any.
104    SourceLocation ExportLoc;
105    TryConsumeToken(tok::kw_export, ExportLoc);
106
107    // Consume the 'template', which should be here.
108    SourceLocation TemplateLoc;
109    if (!TryConsumeToken(tok::kw_template, TemplateLoc)) {
110      Diag(Tok.getLocation(), diag::err_expected_template);
111      return nullptr;
112    }
113
114    // Parse the '<' template-parameter-list '>'
115    SourceLocation LAngleLoc, RAngleLoc;
116    SmallVector<Decl*, 4> TemplateParams;
117    if (ParseTemplateParameters(CurTemplateDepthTracker.getDepth(),
118                                TemplateParams, LAngleLoc, RAngleLoc)) {
119      // Skip until the semi-colon or a '}'.
120      SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
121      TryConsumeToken(tok::semi);
122      return nullptr;
123    }
124
125    ParamLists.push_back(
126      Actions.ActOnTemplateParameterList(CurTemplateDepthTracker.getDepth(),
127                                         ExportLoc,
128                                         TemplateLoc, LAngleLoc,
129                                         TemplateParams.data(),
130                                         TemplateParams.size(), RAngleLoc));
131
132    if (!TemplateParams.empty()) {
133      isSpecialization = false;
134      ++CurTemplateDepthTracker;
135
136      if (TryConsumeToken(tok::kw_requires)) {
137        ExprResult ER =
138            Actions.CorrectDelayedTyposInExpr(ParseConstraintExpression());
139        if (!ER.isUsable()) {
140          // Skip until the semi-colon or a '}'.
141          SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
142          TryConsumeToken(tok::semi);
143          return nullptr;
144        }
145      }
146    } else {
147      LastParamListWasEmpty = true;
148    }
149  } while (Tok.isOneOf(tok::kw_export, tok::kw_template));
150
151  // Parse the actual template declaration.
152  return ParseSingleDeclarationAfterTemplate(Context,
153                                             ParsedTemplateInfo(&ParamLists,
154                                                             isSpecialization,
155                                                         LastParamListWasEmpty),
156                                             ParsingTemplateParams,
157                                             DeclEnd, AS, AccessAttrs);
158}
159
160/// \brief Parse a single declaration that declares a template,
161/// template specialization, or explicit instantiation of a template.
162///
163/// \param DeclEnd will receive the source location of the last token
164/// within this declaration.
165///
166/// \param AS the access specifier associated with this
167/// declaration. Will be AS_none for namespace-scope declarations.
168///
169/// \returns the new declaration.
170Decl *
171Parser::ParseSingleDeclarationAfterTemplate(
172                                       unsigned Context,
173                                       const ParsedTemplateInfo &TemplateInfo,
174                                       ParsingDeclRAIIObject &DiagsFromTParams,
175                                       SourceLocation &DeclEnd,
176                                       AccessSpecifier AS,
177                                       AttributeList *AccessAttrs) {
178  assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
179         "Template information required");
180
181  if (Tok.is(tok::kw_static_assert)) {
182    // A static_assert declaration may not be templated.
183    Diag(Tok.getLocation(), diag::err_templated_invalid_declaration)
184      << TemplateInfo.getSourceRange();
185    // Parse the static_assert declaration to improve error recovery.
186    return ParseStaticAssertDeclaration(DeclEnd);
187  }
188
189  if (Context == Declarator::MemberContext) {
190    // We are parsing a member template.
191    ParseCXXClassMemberDeclaration(AS, AccessAttrs, TemplateInfo,
192                                   &DiagsFromTParams);
193    return nullptr;
194  }
195
196  ParsedAttributesWithRange prefixAttrs(AttrFactory);
197  MaybeParseCXX11Attributes(prefixAttrs);
198
199  if (Tok.is(tok::kw_using))
200    return ParseUsingDirectiveOrDeclaration(Context, TemplateInfo, DeclEnd,
201                                            prefixAttrs);
202
203  // Parse the declaration specifiers, stealing any diagnostics from
204  // the template parameters.
205  ParsingDeclSpec DS(*this, &DiagsFromTParams);
206
207  ParseDeclarationSpecifiers(DS, TemplateInfo, AS,
208                             getDeclSpecContextFromDeclaratorContext(Context));
209
210  if (Tok.is(tok::semi)) {
211    ProhibitAttributes(prefixAttrs);
212    DeclEnd = ConsumeToken();
213    Decl *Decl = Actions.ParsedFreeStandingDeclSpec(
214        getCurScope(), AS, DS,
215        TemplateInfo.TemplateParams ? *TemplateInfo.TemplateParams
216                                    : MultiTemplateParamsArg(),
217        TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation);
218    DS.complete(Decl);
219    return Decl;
220  }
221
222  // Move the attributes from the prefix into the DS.
223  if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation)
224    ProhibitAttributes(prefixAttrs);
225  else
226    DS.takeAttributesFrom(prefixAttrs);
227
228  // Parse the declarator.
229  ParsingDeclarator DeclaratorInfo(*this, DS, (Declarator::TheContext)Context);
230  ParseDeclarator(DeclaratorInfo);
231  // Error parsing the declarator?
232  if (!DeclaratorInfo.hasName()) {
233    // If so, skip until the semi-colon or a }.
234    SkipUntil(tok::r_brace, StopAtSemi | StopBeforeMatch);
235    if (Tok.is(tok::semi))
236      ConsumeToken();
237    return nullptr;
238  }
239
240  LateParsedAttrList LateParsedAttrs(true);
241  if (DeclaratorInfo.isFunctionDeclarator())
242    MaybeParseGNUAttributes(DeclaratorInfo, &LateParsedAttrs);
243
244  if (DeclaratorInfo.isFunctionDeclarator() &&
245      isStartOfFunctionDefinition(DeclaratorInfo)) {
246
247    // Function definitions are only allowed at file scope and in C++ classes.
248    // The C++ inline method definition case is handled elsewhere, so we only
249    // need to handle the file scope definition case.
250    if (Context != Declarator::FileContext) {
251      Diag(Tok, diag::err_function_definition_not_allowed);
252      SkipMalformedDecl();
253      return nullptr;
254    }
255
256    if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
257      // Recover by ignoring the 'typedef'. This was probably supposed to be
258      // the 'typename' keyword, which we should have already suggested adding
259      // if it's appropriate.
260      Diag(DS.getStorageClassSpecLoc(), diag::err_function_declared_typedef)
261        << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
262      DS.ClearStorageClassSpecs();
263    }
264
265    if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
266      if (DeclaratorInfo.getName().getKind() != UnqualifiedId::IK_TemplateId) {
267        // If the declarator-id is not a template-id, issue a diagnostic and
268        // recover by ignoring the 'template' keyword.
269        Diag(Tok, diag::err_template_defn_explicit_instantiation) << 0;
270        return ParseFunctionDefinition(DeclaratorInfo, ParsedTemplateInfo(),
271                                       &LateParsedAttrs);
272      } else {
273        SourceLocation LAngleLoc
274          = PP.getLocForEndOfToken(TemplateInfo.TemplateLoc);
275        Diag(DeclaratorInfo.getIdentifierLoc(),
276             diag::err_explicit_instantiation_with_definition)
277            << SourceRange(TemplateInfo.TemplateLoc)
278            << FixItHint::CreateInsertion(LAngleLoc, "<>");
279
280        // Recover as if it were an explicit specialization.
281        TemplateParameterLists FakedParamLists;
282        FakedParamLists.push_back(Actions.ActOnTemplateParameterList(
283            0, SourceLocation(), TemplateInfo.TemplateLoc, LAngleLoc, nullptr,
284            0, LAngleLoc));
285
286        return ParseFunctionDefinition(
287            DeclaratorInfo, ParsedTemplateInfo(&FakedParamLists,
288                                               /*isSpecialization=*/true,
289                                               /*LastParamListWasEmpty=*/true),
290            &LateParsedAttrs);
291      }
292    }
293    return ParseFunctionDefinition(DeclaratorInfo, TemplateInfo,
294                                   &LateParsedAttrs);
295  }
296
297  // Parse this declaration.
298  Decl *ThisDecl = ParseDeclarationAfterDeclarator(DeclaratorInfo,
299                                                   TemplateInfo);
300
301  if (Tok.is(tok::comma)) {
302    Diag(Tok, diag::err_multiple_template_declarators)
303      << (int)TemplateInfo.Kind;
304    SkipUntil(tok::semi);
305    return ThisDecl;
306  }
307
308  // Eat the semi colon after the declaration.
309  ExpectAndConsumeSemi(diag::err_expected_semi_declaration);
310  if (LateParsedAttrs.size() > 0)
311    ParseLexedAttributeList(LateParsedAttrs, ThisDecl, true, false);
312  DeclaratorInfo.complete(ThisDecl);
313  return ThisDecl;
314}
315
316/// ParseTemplateParameters - Parses a template-parameter-list enclosed in
317/// angle brackets. Depth is the depth of this template-parameter-list, which
318/// is the number of template headers directly enclosing this template header.
319/// TemplateParams is the current list of template parameters we're building.
320/// The template parameter we parse will be added to this list. LAngleLoc and
321/// RAngleLoc will receive the positions of the '<' and '>', respectively,
322/// that enclose this template parameter list.
323///
324/// \returns true if an error occurred, false otherwise.
325bool Parser::ParseTemplateParameters(unsigned Depth,
326                               SmallVectorImpl<Decl*> &TemplateParams,
327                                     SourceLocation &LAngleLoc,
328                                     SourceLocation &RAngleLoc) {
329  // Get the template parameter list.
330  if (!TryConsumeToken(tok::less, LAngleLoc)) {
331    Diag(Tok.getLocation(), diag::err_expected_less_after) << "template";
332    return true;
333  }
334
335  // Try to parse the template parameter list.
336  bool Failed = false;
337  if (!Tok.is(tok::greater) && !Tok.is(tok::greatergreater))
338    Failed = ParseTemplateParameterList(Depth, TemplateParams);
339
340  if (Tok.is(tok::greatergreater)) {
341    // No diagnostic required here: a template-parameter-list can only be
342    // followed by a declaration or, for a template template parameter, the
343    // 'class' keyword. Therefore, the second '>' will be diagnosed later.
344    // This matters for elegant diagnosis of:
345    //   template<template<typename>> struct S;
346    Tok.setKind(tok::greater);
347    RAngleLoc = Tok.getLocation();
348    Tok.setLocation(Tok.getLocation().getLocWithOffset(1));
349  } else if (!TryConsumeToken(tok::greater, RAngleLoc) && Failed) {
350    Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
351    return true;
352  }
353  return false;
354}
355
356/// ParseTemplateParameterList - Parse a template parameter list. If
357/// the parsing fails badly (i.e., closing bracket was left out), this
358/// will try to put the token stream in a reasonable position (closing
359/// a statement, etc.) and return false.
360///
361///       template-parameter-list:    [C++ temp]
362///         template-parameter
363///         template-parameter-list ',' template-parameter
364bool
365Parser::ParseTemplateParameterList(unsigned Depth,
366                             SmallVectorImpl<Decl*> &TemplateParams) {
367  while (1) {
368    if (Decl *TmpParam
369          = ParseTemplateParameter(Depth, TemplateParams.size())) {
370      TemplateParams.push_back(TmpParam);
371    } else {
372      // If we failed to parse a template parameter, skip until we find
373      // a comma or closing brace.
374      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
375                StopAtSemi | StopBeforeMatch);
376    }
377
378    // Did we find a comma or the end of the template parameter list?
379    if (Tok.is(tok::comma)) {
380      ConsumeToken();
381    } else if (Tok.isOneOf(tok::greater, tok::greatergreater)) {
382      // Don't consume this... that's done by template parser.
383      break;
384    } else {
385      // Somebody probably forgot to close the template. Skip ahead and
386      // try to get out of the expression. This error is currently
387      // subsumed by whatever goes on in ParseTemplateParameter.
388      Diag(Tok.getLocation(), diag::err_expected_comma_greater);
389      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
390                StopAtSemi | StopBeforeMatch);
391      return false;
392    }
393  }
394  return true;
395}
396
397/// \brief Determine whether the parser is at the start of a template
398/// type parameter.
399bool Parser::isStartOfTemplateTypeParameter() {
400  if (Tok.is(tok::kw_class)) {
401    // "class" may be the start of an elaborated-type-specifier or a
402    // type-parameter. Per C++ [temp.param]p3, we prefer the type-parameter.
403    switch (NextToken().getKind()) {
404    case tok::equal:
405    case tok::comma:
406    case tok::greater:
407    case tok::greatergreater:
408    case tok::ellipsis:
409      return true;
410
411    case tok::identifier:
412      // This may be either a type-parameter or an elaborated-type-specifier.
413      // We have to look further.
414      break;
415
416    default:
417      return false;
418    }
419
420    switch (GetLookAheadToken(2).getKind()) {
421    case tok::equal:
422    case tok::comma:
423    case tok::greater:
424    case tok::greatergreater:
425      return true;
426
427    default:
428      return false;
429    }
430  }
431
432  if (Tok.isNot(tok::kw_typename))
433    return false;
434
435  // C++ [temp.param]p2:
436  //   There is no semantic difference between class and typename in a
437  //   template-parameter. typename followed by an unqualified-id
438  //   names a template type parameter. typename followed by a
439  //   qualified-id denotes the type in a non-type
440  //   parameter-declaration.
441  Token Next = NextToken();
442
443  // If we have an identifier, skip over it.
444  if (Next.getKind() == tok::identifier)
445    Next = GetLookAheadToken(2);
446
447  switch (Next.getKind()) {
448  case tok::equal:
449  case tok::comma:
450  case tok::greater:
451  case tok::greatergreater:
452  case tok::ellipsis:
453    return true;
454
455  default:
456    return false;
457  }
458}
459
460/// ParseTemplateParameter - Parse a template-parameter (C++ [temp.param]).
461///
462///       template-parameter: [C++ temp.param]
463///         type-parameter
464///         parameter-declaration
465///
466///       type-parameter: (see below)
467///         'class' ...[opt] identifier[opt]
468///         'class' identifier[opt] '=' type-id
469///         'typename' ...[opt] identifier[opt]
470///         'typename' identifier[opt] '=' type-id
471///         'template' '<' template-parameter-list '>'
472///               'class' ...[opt] identifier[opt]
473///         'template' '<' template-parameter-list '>' 'class' identifier[opt]
474///               = id-expression
475Decl *Parser::ParseTemplateParameter(unsigned Depth, unsigned Position) {
476  if (isStartOfTemplateTypeParameter())
477    return ParseTypeParameter(Depth, Position);
478
479  if (Tok.is(tok::kw_template))
480    return ParseTemplateTemplateParameter(Depth, Position);
481
482  // If it's none of the above, then it must be a parameter declaration.
483  // NOTE: This will pick up errors in the closure of the template parameter
484  // list (e.g., template < ; Check here to implement >> style closures.
485  return ParseNonTypeTemplateParameter(Depth, Position);
486}
487
488/// ParseTypeParameter - Parse a template type parameter (C++ [temp.param]).
489/// Other kinds of template parameters are parsed in
490/// ParseTemplateTemplateParameter and ParseNonTypeTemplateParameter.
491///
492///       type-parameter:     [C++ temp.param]
493///         'class' ...[opt][C++0x] identifier[opt]
494///         'class' identifier[opt] '=' type-id
495///         'typename' ...[opt][C++0x] identifier[opt]
496///         'typename' identifier[opt] '=' type-id
497Decl *Parser::ParseTypeParameter(unsigned Depth, unsigned Position) {
498  assert(Tok.isOneOf(tok::kw_class, tok::kw_typename) &&
499         "A type-parameter starts with 'class' or 'typename'");
500
501  // Consume the 'class' or 'typename' keyword.
502  bool TypenameKeyword = Tok.is(tok::kw_typename);
503  SourceLocation KeyLoc = ConsumeToken();
504
505  // Grab the ellipsis (if given).
506  SourceLocation EllipsisLoc;
507  if (TryConsumeToken(tok::ellipsis, EllipsisLoc)) {
508    Diag(EllipsisLoc,
509         getLangOpts().CPlusPlus11
510           ? diag::warn_cxx98_compat_variadic_templates
511           : diag::ext_variadic_templates);
512  }
513
514  // Grab the template parameter name (if given)
515  SourceLocation NameLoc;
516  IdentifierInfo *ParamName = nullptr;
517  if (Tok.is(tok::identifier)) {
518    ParamName = Tok.getIdentifierInfo();
519    NameLoc = ConsumeToken();
520  } else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
521                         tok::greatergreater)) {
522    // Unnamed template parameter. Don't have to do anything here, just
523    // don't consume this token.
524  } else {
525    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
526    return nullptr;
527  }
528
529  // Recover from misplaced ellipsis.
530  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
531  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
532    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
533
534  // Grab a default argument (if available).
535  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
536  // we introduce the type parameter into the local scope.
537  SourceLocation EqualLoc;
538  ParsedType DefaultArg;
539  if (TryConsumeToken(tok::equal, EqualLoc))
540    DefaultArg = ParseTypeName(/*Range=*/nullptr,
541                               Declarator::TemplateTypeArgContext).get();
542
543  return Actions.ActOnTypeParameter(getCurScope(), TypenameKeyword, EllipsisLoc,
544                                    KeyLoc, ParamName, NameLoc, Depth, Position,
545                                    EqualLoc, DefaultArg);
546}
547
548/// ParseTemplateTemplateParameter - Handle the parsing of template
549/// template parameters.
550///
551///       type-parameter:    [C++ temp.param]
552///         'template' '<' template-parameter-list '>' type-parameter-key
553///                  ...[opt] identifier[opt]
554///         'template' '<' template-parameter-list '>' type-parameter-key
555///                  identifier[opt] = id-expression
556///       type-parameter-key:
557///         'class'
558///         'typename'       [C++1z]
559Decl *
560Parser::ParseTemplateTemplateParameter(unsigned Depth, unsigned Position) {
561  assert(Tok.is(tok::kw_template) && "Expected 'template' keyword");
562
563  // Handle the template <...> part.
564  SourceLocation TemplateLoc = ConsumeToken();
565  SmallVector<Decl*,8> TemplateParams;
566  SourceLocation LAngleLoc, RAngleLoc;
567  {
568    ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
569    if (ParseTemplateParameters(Depth + 1, TemplateParams, LAngleLoc,
570                               RAngleLoc)) {
571      return nullptr;
572    }
573  }
574
575  // Provide an ExtWarn if the C++1z feature of using 'typename' here is used.
576  // Generate a meaningful error if the user forgot to put class before the
577  // identifier, comma, or greater. Provide a fixit if the identifier, comma,
578  // or greater appear immediately or after 'struct'. In the latter case,
579  // replace the keyword with 'class'.
580  if (!TryConsumeToken(tok::kw_class)) {
581    bool Replace = Tok.isOneOf(tok::kw_typename, tok::kw_struct);
582    const Token &Next = Tok.is(tok::kw_struct) ? NextToken() : Tok;
583    if (Tok.is(tok::kw_typename)) {
584      Diag(Tok.getLocation(),
585           getLangOpts().CPlusPlus1z
586               ? diag::warn_cxx14_compat_template_template_param_typename
587               : diag::ext_template_template_param_typename)
588        << (!getLangOpts().CPlusPlus1z
589                ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
590                : FixItHint());
591    } else if (Next.isOneOf(tok::identifier, tok::comma, tok::greater,
592                            tok::greatergreater, tok::ellipsis)) {
593      Diag(Tok.getLocation(), diag::err_class_on_template_template_param)
594        << (Replace ? FixItHint::CreateReplacement(Tok.getLocation(), "class")
595                    : FixItHint::CreateInsertion(Tok.getLocation(), "class "));
596    } else
597      Diag(Tok.getLocation(), diag::err_class_on_template_template_param);
598
599    if (Replace)
600      ConsumeToken();
601  }
602
603  // Parse the ellipsis, if given.
604  SourceLocation EllipsisLoc;
605  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
606    Diag(EllipsisLoc,
607         getLangOpts().CPlusPlus11
608           ? diag::warn_cxx98_compat_variadic_templates
609           : diag::ext_variadic_templates);
610
611  // Get the identifier, if given.
612  SourceLocation NameLoc;
613  IdentifierInfo *ParamName = nullptr;
614  if (Tok.is(tok::identifier)) {
615    ParamName = Tok.getIdentifierInfo();
616    NameLoc = ConsumeToken();
617  } else if (Tok.isOneOf(tok::equal, tok::comma, tok::greater,
618                         tok::greatergreater)) {
619    // Unnamed template parameter. Don't have to do anything here, just
620    // don't consume this token.
621  } else {
622    Diag(Tok.getLocation(), diag::err_expected) << tok::identifier;
623    return nullptr;
624  }
625
626  // Recover from misplaced ellipsis.
627  bool AlreadyHasEllipsis = EllipsisLoc.isValid();
628  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
629    DiagnoseMisplacedEllipsis(EllipsisLoc, NameLoc, AlreadyHasEllipsis, true);
630
631  TemplateParameterList *ParamList =
632    Actions.ActOnTemplateParameterList(Depth, SourceLocation(),
633                                       TemplateLoc, LAngleLoc,
634                                       TemplateParams.data(),
635                                       TemplateParams.size(),
636                                       RAngleLoc);
637
638  // Grab a default argument (if available).
639  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
640  // we introduce the template parameter into the local scope.
641  SourceLocation EqualLoc;
642  ParsedTemplateArgument DefaultArg;
643  if (TryConsumeToken(tok::equal, EqualLoc)) {
644    DefaultArg = ParseTemplateTemplateArgument();
645    if (DefaultArg.isInvalid()) {
646      Diag(Tok.getLocation(),
647           diag::err_default_template_template_parameter_not_template);
648      SkipUntil(tok::comma, tok::greater, tok::greatergreater,
649                StopAtSemi | StopBeforeMatch);
650    }
651  }
652
653  return Actions.ActOnTemplateTemplateParameter(getCurScope(), TemplateLoc,
654                                                ParamList, EllipsisLoc,
655                                                ParamName, NameLoc, Depth,
656                                                Position, EqualLoc, DefaultArg);
657}
658
659/// ParseNonTypeTemplateParameter - Handle the parsing of non-type
660/// template parameters (e.g., in "template<int Size> class array;").
661///
662///       template-parameter:
663///         ...
664///         parameter-declaration
665Decl *
666Parser::ParseNonTypeTemplateParameter(unsigned Depth, unsigned Position) {
667  // Parse the declaration-specifiers (i.e., the type).
668  // FIXME: The type should probably be restricted in some way... Not all
669  // declarators (parts of declarators?) are accepted for parameters.
670  DeclSpec DS(AttrFactory);
671  ParseDeclarationSpecifiers(DS);
672
673  // Parse this as a typename.
674  Declarator ParamDecl(DS, Declarator::TemplateParamContext);
675  ParseDeclarator(ParamDecl);
676  if (DS.getTypeSpecType() == DeclSpec::TST_unspecified) {
677    Diag(Tok.getLocation(), diag::err_expected_template_parameter);
678    return nullptr;
679  }
680
681  // Recover from misplaced ellipsis.
682  SourceLocation EllipsisLoc;
683  if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
684    DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, ParamDecl);
685
686  // If there is a default value, parse it.
687  // Per C++0x [basic.scope.pdecl]p9, we parse the default argument before
688  // we introduce the template parameter into the local scope.
689  SourceLocation EqualLoc;
690  ExprResult DefaultArg;
691  if (TryConsumeToken(tok::equal, EqualLoc)) {
692    // C++ [temp.param]p15:
693    //   When parsing a default template-argument for a non-type
694    //   template-parameter, the first non-nested > is taken as the
695    //   end of the template-parameter-list rather than a greater-than
696    //   operator.
697    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
698    EnterExpressionEvaluationContext ConstantEvaluated(Actions,
699                                                       Sema::ConstantEvaluated);
700
701    DefaultArg = Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression());
702    if (DefaultArg.isInvalid())
703      SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
704  }
705
706  // Create the parameter.
707  return Actions.ActOnNonTypeTemplateParameter(getCurScope(), ParamDecl,
708                                               Depth, Position, EqualLoc,
709                                               DefaultArg.get());
710}
711
712void Parser::DiagnoseMisplacedEllipsis(SourceLocation EllipsisLoc,
713                                       SourceLocation CorrectLoc,
714                                       bool AlreadyHasEllipsis,
715                                       bool IdentifierHasName) {
716  FixItHint Insertion;
717  if (!AlreadyHasEllipsis)
718    Insertion = FixItHint::CreateInsertion(CorrectLoc, "...");
719  Diag(EllipsisLoc, diag::err_misplaced_ellipsis_in_declaration)
720      << FixItHint::CreateRemoval(EllipsisLoc) << Insertion
721      << !IdentifierHasName;
722}
723
724void Parser::DiagnoseMisplacedEllipsisInDeclarator(SourceLocation EllipsisLoc,
725                                                   Declarator &D) {
726  assert(EllipsisLoc.isValid());
727  bool AlreadyHasEllipsis = D.getEllipsisLoc().isValid();
728  if (!AlreadyHasEllipsis)
729    D.setEllipsisLoc(EllipsisLoc);
730  DiagnoseMisplacedEllipsis(EllipsisLoc, D.getIdentifierLoc(),
731                            AlreadyHasEllipsis, D.hasName());
732}
733
734/// \brief Parses a '>' at the end of a template list.
735///
736/// If this function encounters '>>', '>>>', '>=', or '>>=', it tries
737/// to determine if these tokens were supposed to be a '>' followed by
738/// '>', '>>', '>=', or '>='. It emits an appropriate diagnostic if necessary.
739///
740/// \param RAngleLoc the location of the consumed '>'.
741///
742/// \param ConsumeLastToken if true, the '>' is consumed.
743///
744/// \param ObjCGenericList if true, this is the '>' closing an Objective-C
745/// type parameter or type argument list, rather than a C++ template parameter
746/// or argument list.
747///
748/// \returns true, if current token does not start with '>', false otherwise.
749bool Parser::ParseGreaterThanInTemplateList(SourceLocation &RAngleLoc,
750                                            bool ConsumeLastToken,
751                                            bool ObjCGenericList) {
752  // What will be left once we've consumed the '>'.
753  tok::TokenKind RemainingToken;
754  const char *ReplacementStr = "> >";
755
756  switch (Tok.getKind()) {
757  default:
758    Diag(Tok.getLocation(), diag::err_expected) << tok::greater;
759    return true;
760
761  case tok::greater:
762    // Determine the location of the '>' token. Only consume this token
763    // if the caller asked us to.
764    RAngleLoc = Tok.getLocation();
765    if (ConsumeLastToken)
766      ConsumeToken();
767    return false;
768
769  case tok::greatergreater:
770    RemainingToken = tok::greater;
771    break;
772
773  case tok::greatergreatergreater:
774    RemainingToken = tok::greatergreater;
775    break;
776
777  case tok::greaterequal:
778    RemainingToken = tok::equal;
779    ReplacementStr = "> =";
780    break;
781
782  case tok::greatergreaterequal:
783    RemainingToken = tok::greaterequal;
784    break;
785  }
786
787  // This template-id is terminated by a token which starts with a '>'. Outside
788  // C++11, this is now error recovery, and in C++11, this is error recovery if
789  // the token isn't '>>' or '>>>'.
790  // '>>>' is for CUDA, where this sequence of characters is parsed into
791  // tok::greatergreatergreater, rather than two separate tokens.
792  //
793  // We always allow this for Objective-C type parameter and type argument
794  // lists.
795  RAngleLoc = Tok.getLocation();
796  Token Next = NextToken();
797  if (!ObjCGenericList) {
798    // The source range of the '>>' or '>=' at the start of the token.
799    CharSourceRange ReplacementRange =
800        CharSourceRange::getCharRange(RAngleLoc,
801            Lexer::AdvanceToTokenCharacter(RAngleLoc, 2, PP.getSourceManager(),
802                                           getLangOpts()));
803
804    // A hint to put a space between the '>>'s. In order to make the hint as
805    // clear as possible, we include the characters either side of the space in
806    // the replacement, rather than just inserting a space at SecondCharLoc.
807    FixItHint Hint1 = FixItHint::CreateReplacement(ReplacementRange,
808                                                   ReplacementStr);
809
810    // A hint to put another space after the token, if it would otherwise be
811    // lexed differently.
812    FixItHint Hint2;
813    if ((RemainingToken == tok::greater ||
814         RemainingToken == tok::greatergreater) &&
815        (Next.isOneOf(tok::greater, tok::greatergreater,
816                      tok::greatergreatergreater, tok::equal,
817                      tok::greaterequal, tok::greatergreaterequal,
818                      tok::equalequal)) &&
819        areTokensAdjacent(Tok, Next))
820      Hint2 = FixItHint::CreateInsertion(Next.getLocation(), " ");
821
822    unsigned DiagId = diag::err_two_right_angle_brackets_need_space;
823    if (getLangOpts().CPlusPlus11 &&
824        (Tok.is(tok::greatergreater) || Tok.is(tok::greatergreatergreater)))
825      DiagId = diag::warn_cxx98_compat_two_right_angle_brackets;
826    else if (Tok.is(tok::greaterequal))
827      DiagId = diag::err_right_angle_bracket_equal_needs_space;
828    Diag(Tok.getLocation(), DiagId) << Hint1 << Hint2;
829  }
830
831  // Strip the initial '>' from the token.
832  if (RemainingToken == tok::equal && Next.is(tok::equal) &&
833      areTokensAdjacent(Tok, Next)) {
834    // Join two adjacent '=' tokens into one, for cases like:
835    //   void (*p)() = f<int>;
836    //   return f<int>==p;
837    ConsumeToken();
838    Tok.setKind(tok::equalequal);
839    Tok.setLength(Tok.getLength() + 1);
840  } else {
841    Tok.setKind(RemainingToken);
842    Tok.setLength(Tok.getLength() - 1);
843  }
844  Tok.setLocation(Lexer::AdvanceToTokenCharacter(RAngleLoc, 1,
845                                                 PP.getSourceManager(),
846                                                 getLangOpts()));
847
848  if (!ConsumeLastToken) {
849    // Since we're not supposed to consume the '>' token, we need to push
850    // this token and revert the current token back to the '>'.
851    PP.EnterToken(Tok);
852    Tok.setKind(tok::greater);
853    Tok.setLength(1);
854    Tok.setLocation(RAngleLoc);
855  }
856  return false;
857}
858
859
860/// \brief Parses a template-id that after the template name has
861/// already been parsed.
862///
863/// This routine takes care of parsing the enclosed template argument
864/// list ('<' template-parameter-list [opt] '>') and placing the
865/// results into a form that can be transferred to semantic analysis.
866///
867/// \param Template the template declaration produced by isTemplateName
868///
869/// \param TemplateNameLoc the source location of the template name
870///
871/// \param SS if non-NULL, the nested-name-specifier preceding the
872/// template name.
873///
874/// \param ConsumeLastToken if true, then we will consume the last
875/// token that forms the template-id. Otherwise, we will leave the
876/// last token in the stream (e.g., so that it can be replaced with an
877/// annotation token).
878bool
879Parser::ParseTemplateIdAfterTemplateName(TemplateTy Template,
880                                         SourceLocation TemplateNameLoc,
881                                         const CXXScopeSpec &SS,
882                                         bool ConsumeLastToken,
883                                         SourceLocation &LAngleLoc,
884                                         TemplateArgList &TemplateArgs,
885                                         SourceLocation &RAngleLoc) {
886  assert(Tok.is(tok::less) && "Must have already parsed the template-name");
887
888  // Consume the '<'.
889  LAngleLoc = ConsumeToken();
890
891  // Parse the optional template-argument-list.
892  bool Invalid = false;
893  {
894    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
895    if (Tok.isNot(tok::greater) && Tok.isNot(tok::greatergreater))
896      Invalid = ParseTemplateArgumentList(TemplateArgs);
897
898    if (Invalid) {
899      // Try to find the closing '>'.
900      if (ConsumeLastToken)
901        SkipUntil(tok::greater, StopAtSemi);
902      else
903        SkipUntil(tok::greater, StopAtSemi | StopBeforeMatch);
904      return true;
905    }
906  }
907
908  return ParseGreaterThanInTemplateList(RAngleLoc, ConsumeLastToken,
909                                        /*ObjCGenericList=*/false);
910}
911
912/// \brief Replace the tokens that form a simple-template-id with an
913/// annotation token containing the complete template-id.
914///
915/// The first token in the stream must be the name of a template that
916/// is followed by a '<'. This routine will parse the complete
917/// simple-template-id and replace the tokens with a single annotation
918/// token with one of two different kinds: if the template-id names a
919/// type (and \p AllowTypeAnnotation is true), the annotation token is
920/// a type annotation that includes the optional nested-name-specifier
921/// (\p SS). Otherwise, the annotation token is a template-id
922/// annotation that does not include the optional
923/// nested-name-specifier.
924///
925/// \param Template  the declaration of the template named by the first
926/// token (an identifier), as returned from \c Action::isTemplateName().
927///
928/// \param TNK the kind of template that \p Template
929/// refers to, as returned from \c Action::isTemplateName().
930///
931/// \param SS if non-NULL, the nested-name-specifier that precedes
932/// this template name.
933///
934/// \param TemplateKWLoc if valid, specifies that this template-id
935/// annotation was preceded by the 'template' keyword and gives the
936/// location of that keyword. If invalid (the default), then this
937/// template-id was not preceded by a 'template' keyword.
938///
939/// \param AllowTypeAnnotation if true (the default), then a
940/// simple-template-id that refers to a class template, template
941/// template parameter, or other template that produces a type will be
942/// replaced with a type annotation token. Otherwise, the
943/// simple-template-id is always replaced with a template-id
944/// annotation token.
945///
946/// If an unrecoverable parse error occurs and no annotation token can be
947/// formed, this function returns true.
948///
949bool Parser::AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
950                                     CXXScopeSpec &SS,
951                                     SourceLocation TemplateKWLoc,
952                                     UnqualifiedId &TemplateName,
953                                     bool AllowTypeAnnotation) {
954  assert(getLangOpts().CPlusPlus && "Can only annotate template-ids in C++");
955  assert(Template && Tok.is(tok::less) &&
956         "Parser isn't at the beginning of a template-id");
957
958  // Consume the template-name.
959  SourceLocation TemplateNameLoc = TemplateName.getSourceRange().getBegin();
960
961  // Parse the enclosed template argument list.
962  SourceLocation LAngleLoc, RAngleLoc;
963  TemplateArgList TemplateArgs;
964  bool Invalid = ParseTemplateIdAfterTemplateName(Template,
965                                                  TemplateNameLoc,
966                                                  SS, false, LAngleLoc,
967                                                  TemplateArgs,
968                                                  RAngleLoc);
969
970  if (Invalid) {
971    // If we failed to parse the template ID but skipped ahead to a >, we're not
972    // going to be able to form a token annotation.  Eat the '>' if present.
973    TryConsumeToken(tok::greater);
974    return true;
975  }
976
977  ASTTemplateArgsPtr TemplateArgsPtr(TemplateArgs);
978
979  // Build the annotation token.
980  if (TNK == TNK_Type_template && AllowTypeAnnotation) {
981    TypeResult Type
982      = Actions.ActOnTemplateIdType(SS, TemplateKWLoc,
983                                    Template, TemplateNameLoc,
984                                    LAngleLoc, TemplateArgsPtr, RAngleLoc);
985    if (Type.isInvalid()) {
986      // If we failed to parse the template ID but skipped ahead to a >, we're not
987      // going to be able to form a token annotation.  Eat the '>' if present.
988      TryConsumeToken(tok::greater);
989      return true;
990    }
991
992    Tok.setKind(tok::annot_typename);
993    setTypeAnnotation(Tok, Type.get());
994    if (SS.isNotEmpty())
995      Tok.setLocation(SS.getBeginLoc());
996    else if (TemplateKWLoc.isValid())
997      Tok.setLocation(TemplateKWLoc);
998    else
999      Tok.setLocation(TemplateNameLoc);
1000  } else {
1001    // Build a template-id annotation token that can be processed
1002    // later.
1003    Tok.setKind(tok::annot_template_id);
1004    TemplateIdAnnotation *TemplateId
1005      = TemplateIdAnnotation::Allocate(TemplateArgs.size(), TemplateIds);
1006    TemplateId->TemplateNameLoc = TemplateNameLoc;
1007    if (TemplateName.getKind() == UnqualifiedId::IK_Identifier) {
1008      TemplateId->Name = TemplateName.Identifier;
1009      TemplateId->Operator = OO_None;
1010    } else {
1011      TemplateId->Name = nullptr;
1012      TemplateId->Operator = TemplateName.OperatorFunctionId.Operator;
1013    }
1014    TemplateId->SS = SS;
1015    TemplateId->TemplateKWLoc = TemplateKWLoc;
1016    TemplateId->Template = Template;
1017    TemplateId->Kind = TNK;
1018    TemplateId->LAngleLoc = LAngleLoc;
1019    TemplateId->RAngleLoc = RAngleLoc;
1020    ParsedTemplateArgument *Args = TemplateId->getTemplateArgs();
1021    for (unsigned Arg = 0, ArgEnd = TemplateArgs.size(); Arg != ArgEnd; ++Arg)
1022      Args[Arg] = ParsedTemplateArgument(TemplateArgs[Arg]);
1023    Tok.setAnnotationValue(TemplateId);
1024    if (TemplateKWLoc.isValid())
1025      Tok.setLocation(TemplateKWLoc);
1026    else
1027      Tok.setLocation(TemplateNameLoc);
1028  }
1029
1030  // Common fields for the annotation token
1031  Tok.setAnnotationEndLoc(RAngleLoc);
1032
1033  // In case the tokens were cached, have Preprocessor replace them with the
1034  // annotation token.
1035  PP.AnnotateCachedTokens(Tok);
1036  return false;
1037}
1038
1039/// \brief Replaces a template-id annotation token with a type
1040/// annotation token.
1041///
1042/// If there was a failure when forming the type from the template-id,
1043/// a type annotation token will still be created, but will have a
1044/// NULL type pointer to signify an error.
1045void Parser::AnnotateTemplateIdTokenAsType() {
1046  assert(Tok.is(tok::annot_template_id) && "Requires template-id tokens");
1047
1048  TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
1049  assert((TemplateId->Kind == TNK_Type_template ||
1050          TemplateId->Kind == TNK_Dependent_template_name) &&
1051         "Only works for type and dependent templates");
1052
1053  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
1054                                     TemplateId->NumArgs);
1055
1056  TypeResult Type
1057    = Actions.ActOnTemplateIdType(TemplateId->SS,
1058                                  TemplateId->TemplateKWLoc,
1059                                  TemplateId->Template,
1060                                  TemplateId->TemplateNameLoc,
1061                                  TemplateId->LAngleLoc,
1062                                  TemplateArgsPtr,
1063                                  TemplateId->RAngleLoc);
1064  // Create the new "type" annotation token.
1065  Tok.setKind(tok::annot_typename);
1066  setTypeAnnotation(Tok, Type.isInvalid() ? ParsedType() : Type.get());
1067  if (TemplateId->SS.isNotEmpty()) // it was a C++ qualified type name.
1068    Tok.setLocation(TemplateId->SS.getBeginLoc());
1069  // End location stays the same
1070
1071  // Replace the template-id annotation token, and possible the scope-specifier
1072  // that precedes it, with the typename annotation token.
1073  PP.AnnotateCachedTokens(Tok);
1074}
1075
1076/// \brief Determine whether the given token can end a template argument.
1077static bool isEndOfTemplateArgument(Token Tok) {
1078  return Tok.isOneOf(tok::comma, tok::greater, tok::greatergreater);
1079}
1080
1081/// \brief Parse a C++ template template argument.
1082ParsedTemplateArgument Parser::ParseTemplateTemplateArgument() {
1083  if (!Tok.is(tok::identifier) && !Tok.is(tok::coloncolon) &&
1084      !Tok.is(tok::annot_cxxscope))
1085    return ParsedTemplateArgument();
1086
1087  // C++0x [temp.arg.template]p1:
1088  //   A template-argument for a template template-parameter shall be the name
1089  //   of a class template or an alias template, expressed as id-expression.
1090  //
1091  // We parse an id-expression that refers to a class template or alias
1092  // template. The grammar we parse is:
1093  //
1094  //   nested-name-specifier[opt] template[opt] identifier ...[opt]
1095  //
1096  // followed by a token that terminates a template argument, such as ',',
1097  // '>', or (in some cases) '>>'.
1098  CXXScopeSpec SS; // nested-name-specifier, if present
1099  ParseOptionalCXXScopeSpecifier(SS, ParsedType(),
1100                                 /*EnteringContext=*/false);
1101
1102  ParsedTemplateArgument Result;
1103  SourceLocation EllipsisLoc;
1104  if (SS.isSet() && Tok.is(tok::kw_template)) {
1105    // Parse the optional 'template' keyword following the
1106    // nested-name-specifier.
1107    SourceLocation TemplateKWLoc = ConsumeToken();
1108
1109    if (Tok.is(tok::identifier)) {
1110      // We appear to have a dependent template name.
1111      UnqualifiedId Name;
1112      Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1113      ConsumeToken(); // the identifier
1114
1115      TryConsumeToken(tok::ellipsis, EllipsisLoc);
1116
1117      // If the next token signals the end of a template argument,
1118      // then we have a dependent template name that could be a template
1119      // template argument.
1120      TemplateTy Template;
1121      if (isEndOfTemplateArgument(Tok) &&
1122          Actions.ActOnDependentTemplateName(getCurScope(),
1123                                             SS, TemplateKWLoc, Name,
1124                                             /*ObjectType=*/ ParsedType(),
1125                                             /*EnteringContext=*/false,
1126                                             Template))
1127        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1128    }
1129  } else if (Tok.is(tok::identifier)) {
1130    // We may have a (non-dependent) template name.
1131    TemplateTy Template;
1132    UnqualifiedId Name;
1133    Name.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
1134    ConsumeToken(); // the identifier
1135
1136    TryConsumeToken(tok::ellipsis, EllipsisLoc);
1137
1138    if (isEndOfTemplateArgument(Tok)) {
1139      bool MemberOfUnknownSpecialization;
1140      TemplateNameKind TNK = Actions.isTemplateName(getCurScope(), SS,
1141                                               /*hasTemplateKeyword=*/false,
1142                                                    Name,
1143                                               /*ObjectType=*/ ParsedType(),
1144                                                    /*EnteringContext=*/false,
1145                                                    Template,
1146                                                MemberOfUnknownSpecialization);
1147      if (TNK == TNK_Dependent_template_name || TNK == TNK_Type_template) {
1148        // We have an id-expression that refers to a class template or
1149        // (C++0x) alias template.
1150        Result = ParsedTemplateArgument(SS, Template, Name.StartLocation);
1151      }
1152    }
1153  }
1154
1155  // If this is a pack expansion, build it as such.
1156  if (EllipsisLoc.isValid() && !Result.isInvalid())
1157    Result = Actions.ActOnPackExpansion(Result, EllipsisLoc);
1158
1159  return Result;
1160}
1161
1162/// ParseTemplateArgument - Parse a C++ template argument (C++ [temp.names]).
1163///
1164///       template-argument: [C++ 14.2]
1165///         constant-expression
1166///         type-id
1167///         id-expression
1168ParsedTemplateArgument Parser::ParseTemplateArgument() {
1169  // C++ [temp.arg]p2:
1170  //   In a template-argument, an ambiguity between a type-id and an
1171  //   expression is resolved to a type-id, regardless of the form of
1172  //   the corresponding template-parameter.
1173  //
1174  // Therefore, we initially try to parse a type-id.
1175  if (isCXXTypeId(TypeIdAsTemplateArgument)) {
1176    SourceLocation Loc = Tok.getLocation();
1177    TypeResult TypeArg = ParseTypeName(/*Range=*/nullptr,
1178                                       Declarator::TemplateTypeArgContext);
1179    if (TypeArg.isInvalid())
1180      return ParsedTemplateArgument();
1181
1182    return ParsedTemplateArgument(ParsedTemplateArgument::Type,
1183                                  TypeArg.get().getAsOpaquePtr(),
1184                                  Loc);
1185  }
1186
1187  // Try to parse a template template argument.
1188  {
1189    TentativeParsingAction TPA(*this);
1190
1191    ParsedTemplateArgument TemplateTemplateArgument
1192      = ParseTemplateTemplateArgument();
1193    if (!TemplateTemplateArgument.isInvalid()) {
1194      TPA.Commit();
1195      return TemplateTemplateArgument;
1196    }
1197
1198    // Revert this tentative parse to parse a non-type template argument.
1199    TPA.Revert();
1200  }
1201
1202  // Parse a non-type template argument.
1203  SourceLocation Loc = Tok.getLocation();
1204  ExprResult ExprArg = ParseConstantExpression(MaybeTypeCast);
1205  if (ExprArg.isInvalid() || !ExprArg.get())
1206    return ParsedTemplateArgument();
1207
1208  return ParsedTemplateArgument(ParsedTemplateArgument::NonType,
1209                                ExprArg.get(), Loc);
1210}
1211
1212/// \brief Determine whether the current tokens can only be parsed as a
1213/// template argument list (starting with the '<') and never as a '<'
1214/// expression.
1215bool Parser::IsTemplateArgumentList(unsigned Skip) {
1216  struct AlwaysRevertAction : TentativeParsingAction {
1217    AlwaysRevertAction(Parser &P) : TentativeParsingAction(P) { }
1218    ~AlwaysRevertAction() { Revert(); }
1219  } Tentative(*this);
1220
1221  while (Skip) {
1222    ConsumeToken();
1223    --Skip;
1224  }
1225
1226  // '<'
1227  if (!TryConsumeToken(tok::less))
1228    return false;
1229
1230  // An empty template argument list.
1231  if (Tok.is(tok::greater))
1232    return true;
1233
1234  // See whether we have declaration specifiers, which indicate a type.
1235  while (isCXXDeclarationSpecifier() == TPResult::True)
1236    ConsumeToken();
1237
1238  // If we have a '>' or a ',' then this is a template argument list.
1239  return Tok.isOneOf(tok::greater, tok::comma);
1240}
1241
1242/// ParseTemplateArgumentList - Parse a C++ template-argument-list
1243/// (C++ [temp.names]). Returns true if there was an error.
1244///
1245///       template-argument-list: [C++ 14.2]
1246///         template-argument
1247///         template-argument-list ',' template-argument
1248bool
1249Parser::ParseTemplateArgumentList(TemplateArgList &TemplateArgs) {
1250  // Template argument lists are constant-evaluation contexts.
1251  EnterExpressionEvaluationContext EvalContext(Actions,Sema::ConstantEvaluated);
1252  ColonProtectionRAIIObject ColonProtection(*this, false);
1253
1254  do {
1255    ParsedTemplateArgument Arg = ParseTemplateArgument();
1256    SourceLocation EllipsisLoc;
1257    if (TryConsumeToken(tok::ellipsis, EllipsisLoc))
1258      Arg = Actions.ActOnPackExpansion(Arg, EllipsisLoc);
1259
1260    if (Arg.isInvalid()) {
1261      SkipUntil(tok::comma, tok::greater, StopAtSemi | StopBeforeMatch);
1262      return true;
1263    }
1264
1265    // Save this template argument.
1266    TemplateArgs.push_back(Arg);
1267
1268    // If the next token is a comma, consume it and keep reading
1269    // arguments.
1270  } while (TryConsumeToken(tok::comma));
1271
1272  return false;
1273}
1274
1275/// \brief Parse a C++ explicit template instantiation
1276/// (C++ [temp.explicit]).
1277///
1278///       explicit-instantiation:
1279///         'extern' [opt] 'template' declaration
1280///
1281/// Note that the 'extern' is a GNU extension and C++11 feature.
1282Decl *Parser::ParseExplicitInstantiation(unsigned Context,
1283                                         SourceLocation ExternLoc,
1284                                         SourceLocation TemplateLoc,
1285                                         SourceLocation &DeclEnd,
1286                                         AccessSpecifier AS) {
1287  // This isn't really required here.
1288  ParsingDeclRAIIObject
1289    ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
1290
1291  return ParseSingleDeclarationAfterTemplate(Context,
1292                                             ParsedTemplateInfo(ExternLoc,
1293                                                                TemplateLoc),
1294                                             ParsingTemplateParams,
1295                                             DeclEnd, AS);
1296}
1297
1298SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
1299  if (TemplateParams)
1300    return getTemplateParamsRange(TemplateParams->data(),
1301                                  TemplateParams->size());
1302
1303  SourceRange R(TemplateLoc);
1304  if (ExternLoc.isValid())
1305    R.setBegin(ExternLoc);
1306  return R;
1307}
1308
1309void Parser::LateTemplateParserCallback(void *P, LateParsedTemplate &LPT) {
1310  ((Parser *)P)->ParseLateTemplatedFuncDef(LPT);
1311}
1312
1313/// \brief Late parse a C++ function template in Microsoft mode.
1314void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
1315  if (!LPT.D)
1316     return;
1317
1318  // Get the FunctionDecl.
1319  FunctionDecl *FunD = LPT.D->getAsFunction();
1320  // Track template parameter depth.
1321  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
1322
1323  // To restore the context after late parsing.
1324  Sema::ContextRAII GlobalSavedContext(
1325      Actions, Actions.Context.getTranslationUnitDecl());
1326
1327  SmallVector<ParseScope*, 4> TemplateParamScopeStack;
1328
1329  // Get the list of DeclContexts to reenter.
1330  SmallVector<DeclContext*, 4> DeclContextsToReenter;
1331  DeclContext *DD = FunD;
1332  while (DD && !DD->isTranslationUnit()) {
1333    DeclContextsToReenter.push_back(DD);
1334    DD = DD->getLexicalParent();
1335  }
1336
1337  // Reenter template scopes from outermost to innermost.
1338  SmallVectorImpl<DeclContext *>::reverse_iterator II =
1339      DeclContextsToReenter.rbegin();
1340  for (; II != DeclContextsToReenter.rend(); ++II) {
1341    TemplateParamScopeStack.push_back(new ParseScope(this,
1342          Scope::TemplateParamScope));
1343    unsigned NumParamLists =
1344      Actions.ActOnReenterTemplateScope(getCurScope(), cast<Decl>(*II));
1345    CurTemplateDepthTracker.addDepth(NumParamLists);
1346    if (*II != FunD) {
1347      TemplateParamScopeStack.push_back(new ParseScope(this, Scope::DeclScope));
1348      Actions.PushDeclContext(Actions.getCurScope(), *II);
1349    }
1350  }
1351
1352  assert(!LPT.Toks.empty() && "Empty body!");
1353
1354  // Append the current token at the end of the new token stream so that it
1355  // doesn't get lost.
1356  LPT.Toks.push_back(Tok);
1357  PP.EnterTokenStream(LPT.Toks.data(), LPT.Toks.size(), true, false);
1358
1359  // Consume the previously pushed token.
1360  ConsumeAnyToken(/*ConsumeCodeCompletionTok=*/true);
1361  assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try) &&
1362         "Inline method not starting with '{', ':' or 'try'");
1363
1364  // Parse the method body. Function body parsing code is similar enough
1365  // to be re-used for method bodies as well.
1366  ParseScope FnScope(this, Scope::FnScope|Scope::DeclScope);
1367
1368  // Recreate the containing function DeclContext.
1369  Sema::ContextRAII FunctionSavedContext(Actions,
1370                                         Actions.getContainingDC(FunD));
1371
1372  Actions.ActOnStartOfFunctionDef(getCurScope(), FunD);
1373
1374  if (Tok.is(tok::kw_try)) {
1375    ParseFunctionTryBlock(LPT.D, FnScope);
1376  } else {
1377    if (Tok.is(tok::colon))
1378      ParseConstructorInitializer(LPT.D);
1379    else
1380      Actions.ActOnDefaultCtorInitializers(LPT.D);
1381
1382    if (Tok.is(tok::l_brace)) {
1383      assert((!isa<FunctionTemplateDecl>(LPT.D) ||
1384              cast<FunctionTemplateDecl>(LPT.D)
1385                      ->getTemplateParameters()
1386                      ->getDepth() == TemplateParameterDepth - 1) &&
1387             "TemplateParameterDepth should be greater than the depth of "
1388             "current template being instantiated!");
1389      ParseFunctionStatementBody(LPT.D, FnScope);
1390      Actions.UnmarkAsLateParsedTemplate(FunD);
1391    } else
1392      Actions.ActOnFinishFunctionBody(LPT.D, nullptr);
1393  }
1394
1395  // Exit scopes.
1396  FnScope.Exit();
1397  SmallVectorImpl<ParseScope *>::reverse_iterator I =
1398   TemplateParamScopeStack.rbegin();
1399  for (; I != TemplateParamScopeStack.rend(); ++I)
1400    delete *I;
1401}
1402
1403/// \brief Lex a delayed template function for late parsing.
1404void Parser::LexTemplateFunctionForLateParsing(CachedTokens &Toks) {
1405  tok::TokenKind kind = Tok.getKind();
1406  if (!ConsumeAndStoreFunctionPrologue(Toks)) {
1407    // Consume everything up to (and including) the matching right brace.
1408    ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1409  }
1410
1411  // If we're in a function-try-block, we need to store all the catch blocks.
1412  if (kind == tok::kw_try) {
1413    while (Tok.is(tok::kw_catch)) {
1414      ConsumeAndStoreUntil(tok::l_brace, Toks, /*StopAtSemi=*/false);
1415      ConsumeAndStoreUntil(tok::r_brace, Toks, /*StopAtSemi=*/false);
1416    }
1417  }
1418}
1419