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