1//===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===/
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//  This file implements semantic analysis for C++ templates.
10//===----------------------------------------------------------------------===/
11
12#include "TreeTransform.h"
13#include "clang/AST/ASTConsumer.h"
14#include "clang/AST/ASTContext.h"
15#include "clang/AST/DeclFriend.h"
16#include "clang/AST/DeclTemplate.h"
17#include "clang/AST/Expr.h"
18#include "clang/AST/ExprCXX.h"
19#include "clang/AST/RecursiveASTVisitor.h"
20#include "clang/AST/TypeVisitor.h"
21#include "clang/Basic/LangOptions.h"
22#include "clang/Basic/PartialDiagnostic.h"
23#include "clang/Basic/TargetInfo.h"
24#include "clang/Sema/DeclSpec.h"
25#include "clang/Sema/Lookup.h"
26#include "clang/Sema/ParsedTemplate.h"
27#include "clang/Sema/Scope.h"
28#include "clang/Sema/SemaInternal.h"
29#include "clang/Sema/Template.h"
30#include "clang/Sema/TemplateDeduction.h"
31#include "llvm/ADT/SmallBitVector.h"
32#include "llvm/ADT/SmallString.h"
33#include "llvm/ADT/StringExtras.h"
34using namespace clang;
35using namespace sema;
36
37// Exported for use by Parser.
38SourceRange
39clang::getTemplateParamsRange(TemplateParameterList const * const *Ps,
40                              unsigned N) {
41  if (!N) return SourceRange();
42  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
43}
44
45/// \brief Determine whether the declaration found is acceptable as the name
46/// of a template and, if so, return that template declaration. Otherwise,
47/// returns NULL.
48static NamedDecl *isAcceptableTemplateName(ASTContext &Context,
49                                           NamedDecl *Orig,
50                                           bool AllowFunctionTemplates) {
51  NamedDecl *D = Orig->getUnderlyingDecl();
52
53  if (isa<TemplateDecl>(D)) {
54    if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
55      return nullptr;
56
57    return Orig;
58  }
59
60  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
61    // C++ [temp.local]p1:
62    //   Like normal (non-template) classes, class templates have an
63    //   injected-class-name (Clause 9). The injected-class-name
64    //   can be used with or without a template-argument-list. When
65    //   it is used without a template-argument-list, it is
66    //   equivalent to the injected-class-name followed by the
67    //   template-parameters of the class template enclosed in
68    //   <>. When it is used with a template-argument-list, it
69    //   refers to the specified class template specialization,
70    //   which could be the current specialization or another
71    //   specialization.
72    if (Record->isInjectedClassName()) {
73      Record = cast<CXXRecordDecl>(Record->getDeclContext());
74      if (Record->getDescribedClassTemplate())
75        return Record->getDescribedClassTemplate();
76
77      if (ClassTemplateSpecializationDecl *Spec
78            = dyn_cast<ClassTemplateSpecializationDecl>(Record))
79        return Spec->getSpecializedTemplate();
80    }
81
82    return nullptr;
83  }
84
85  return nullptr;
86}
87
88void Sema::FilterAcceptableTemplateNames(LookupResult &R,
89                                         bool AllowFunctionTemplates) {
90  // The set of class templates we've already seen.
91  llvm::SmallPtrSet<ClassTemplateDecl *, 8> ClassTemplates;
92  LookupResult::Filter filter = R.makeFilter();
93  while (filter.hasNext()) {
94    NamedDecl *Orig = filter.next();
95    NamedDecl *Repl = isAcceptableTemplateName(Context, Orig,
96                                               AllowFunctionTemplates);
97    if (!Repl)
98      filter.erase();
99    else if (Repl != Orig) {
100
101      // C++ [temp.local]p3:
102      //   A lookup that finds an injected-class-name (10.2) can result in an
103      //   ambiguity in certain cases (for example, if it is found in more than
104      //   one base class). If all of the injected-class-names that are found
105      //   refer to specializations of the same class template, and if the name
106      //   is used as a template-name, the reference refers to the class
107      //   template itself and not a specialization thereof, and is not
108      //   ambiguous.
109      if (ClassTemplateDecl *ClassTmpl = dyn_cast<ClassTemplateDecl>(Repl))
110        if (!ClassTemplates.insert(ClassTmpl)) {
111          filter.erase();
112          continue;
113        }
114
115      // FIXME: we promote access to public here as a workaround to
116      // the fact that LookupResult doesn't let us remember that we
117      // found this template through a particular injected class name,
118      // which means we end up doing nasty things to the invariants.
119      // Pretending that access is public is *much* safer.
120      filter.replace(Repl, AS_public);
121    }
122  }
123  filter.done();
124}
125
126bool Sema::hasAnyAcceptableTemplateNames(LookupResult &R,
127                                         bool AllowFunctionTemplates) {
128  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I)
129    if (isAcceptableTemplateName(Context, *I, AllowFunctionTemplates))
130      return true;
131
132  return false;
133}
134
135TemplateNameKind Sema::isTemplateName(Scope *S,
136                                      CXXScopeSpec &SS,
137                                      bool hasTemplateKeyword,
138                                      UnqualifiedId &Name,
139                                      ParsedType ObjectTypePtr,
140                                      bool EnteringContext,
141                                      TemplateTy &TemplateResult,
142                                      bool &MemberOfUnknownSpecialization) {
143  assert(getLangOpts().CPlusPlus && "No template names in C!");
144
145  DeclarationName TName;
146  MemberOfUnknownSpecialization = false;
147
148  switch (Name.getKind()) {
149  case UnqualifiedId::IK_Identifier:
150    TName = DeclarationName(Name.Identifier);
151    break;
152
153  case UnqualifiedId::IK_OperatorFunctionId:
154    TName = Context.DeclarationNames.getCXXOperatorName(
155                                              Name.OperatorFunctionId.Operator);
156    break;
157
158  case UnqualifiedId::IK_LiteralOperatorId:
159    TName = Context.DeclarationNames.getCXXLiteralOperatorName(Name.Identifier);
160    break;
161
162  default:
163    return TNK_Non_template;
164  }
165
166  QualType ObjectType = ObjectTypePtr.get();
167
168  LookupResult R(*this, TName, Name.getLocStart(), LookupOrdinaryName);
169  LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
170                     MemberOfUnknownSpecialization);
171  if (R.empty()) return TNK_Non_template;
172  if (R.isAmbiguous()) {
173    // Suppress diagnostics;  we'll redo this lookup later.
174    R.suppressDiagnostics();
175
176    // FIXME: we might have ambiguous templates, in which case we
177    // should at least parse them properly!
178    return TNK_Non_template;
179  }
180
181  TemplateName Template;
182  TemplateNameKind TemplateKind;
183
184  unsigned ResultCount = R.end() - R.begin();
185  if (ResultCount > 1) {
186    // We assume that we'll preserve the qualifier from a function
187    // template name in other ways.
188    Template = Context.getOverloadedTemplateName(R.begin(), R.end());
189    TemplateKind = TNK_Function_template;
190
191    // We'll do this lookup again later.
192    R.suppressDiagnostics();
193  } else {
194    TemplateDecl *TD = cast<TemplateDecl>((*R.begin())->getUnderlyingDecl());
195
196    if (SS.isSet() && !SS.isInvalid()) {
197      NestedNameSpecifier *Qualifier = SS.getScopeRep();
198      Template = Context.getQualifiedTemplateName(Qualifier,
199                                                  hasTemplateKeyword, TD);
200    } else {
201      Template = TemplateName(TD);
202    }
203
204    if (isa<FunctionTemplateDecl>(TD)) {
205      TemplateKind = TNK_Function_template;
206
207      // We'll do this lookup again later.
208      R.suppressDiagnostics();
209    } else {
210      assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
211             isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD));
212      TemplateKind =
213          isa<VarTemplateDecl>(TD) ? TNK_Var_template : TNK_Type_template;
214    }
215  }
216
217  TemplateResult = TemplateTy::make(Template);
218  return TemplateKind;
219}
220
221bool Sema::DiagnoseUnknownTemplateName(const IdentifierInfo &II,
222                                       SourceLocation IILoc,
223                                       Scope *S,
224                                       const CXXScopeSpec *SS,
225                                       TemplateTy &SuggestedTemplate,
226                                       TemplateNameKind &SuggestedKind) {
227  // We can't recover unless there's a dependent scope specifier preceding the
228  // template name.
229  // FIXME: Typo correction?
230  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
231      computeDeclContext(*SS))
232    return false;
233
234  // The code is missing a 'template' keyword prior to the dependent template
235  // name.
236  NestedNameSpecifier *Qualifier = (NestedNameSpecifier*)SS->getScopeRep();
237  Diag(IILoc, diag::err_template_kw_missing)
238    << Qualifier << II.getName()
239    << FixItHint::CreateInsertion(IILoc, "template ");
240  SuggestedTemplate
241    = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
242  SuggestedKind = TNK_Dependent_template_name;
243  return true;
244}
245
246void Sema::LookupTemplateName(LookupResult &Found,
247                              Scope *S, CXXScopeSpec &SS,
248                              QualType ObjectType,
249                              bool EnteringContext,
250                              bool &MemberOfUnknownSpecialization) {
251  // Determine where to perform name lookup
252  MemberOfUnknownSpecialization = false;
253  DeclContext *LookupCtx = nullptr;
254  bool isDependent = false;
255  if (!ObjectType.isNull()) {
256    // This nested-name-specifier occurs in a member access expression, e.g.,
257    // x->B::f, and we are looking into the type of the object.
258    assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
259    LookupCtx = computeDeclContext(ObjectType);
260    isDependent = ObjectType->isDependentType();
261    assert((isDependent || !ObjectType->isIncompleteType() ||
262            ObjectType->castAs<TagType>()->isBeingDefined()) &&
263           "Caller should have completed object type");
264
265    // Template names cannot appear inside an Objective-C class or object type.
266    if (ObjectType->isObjCObjectOrInterfaceType()) {
267      Found.clear();
268      return;
269    }
270  } else if (SS.isSet()) {
271    // This nested-name-specifier occurs after another nested-name-specifier,
272    // so long into the context associated with the prior nested-name-specifier.
273    LookupCtx = computeDeclContext(SS, EnteringContext);
274    isDependent = isDependentScopeSpecifier(SS);
275
276    // The declaration context must be complete.
277    if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
278      return;
279  }
280
281  bool ObjectTypeSearchedInScope = false;
282  bool AllowFunctionTemplatesInLookup = true;
283  if (LookupCtx) {
284    // Perform "qualified" name lookup into the declaration context we
285    // computed, which is either the type of the base of a member access
286    // expression or the declaration context associated with a prior
287    // nested-name-specifier.
288    LookupQualifiedName(Found, LookupCtx);
289    if (!ObjectType.isNull() && Found.empty()) {
290      // C++ [basic.lookup.classref]p1:
291      //   In a class member access expression (5.2.5), if the . or -> token is
292      //   immediately followed by an identifier followed by a <, the
293      //   identifier must be looked up to determine whether the < is the
294      //   beginning of a template argument list (14.2) or a less-than operator.
295      //   The identifier is first looked up in the class of the object
296      //   expression. If the identifier is not found, it is then looked up in
297      //   the context of the entire postfix-expression and shall name a class
298      //   or function template.
299      if (S) LookupName(Found, S);
300      ObjectTypeSearchedInScope = true;
301      AllowFunctionTemplatesInLookup = false;
302    }
303  } else if (isDependent && (!S || ObjectType.isNull())) {
304    // We cannot look into a dependent object type or nested nme
305    // specifier.
306    MemberOfUnknownSpecialization = true;
307    return;
308  } else {
309    // Perform unqualified name lookup in the current scope.
310    LookupName(Found, S);
311
312    if (!ObjectType.isNull())
313      AllowFunctionTemplatesInLookup = false;
314  }
315
316  if (Found.empty() && !isDependent) {
317    // If we did not find any names, attempt to correct any typos.
318    DeclarationName Name = Found.getLookupName();
319    Found.clear();
320    // Simple filter callback that, for keywords, only accepts the C++ *_cast
321    CorrectionCandidateCallback FilterCCC;
322    FilterCCC.WantTypeSpecifiers = false;
323    FilterCCC.WantExpressionKeywords = false;
324    FilterCCC.WantRemainingKeywords = false;
325    FilterCCC.WantCXXNamedCasts = true;
326    if (TypoCorrection Corrected = CorrectTypo(Found.getLookupNameInfo(),
327                                               Found.getLookupKind(), S, &SS,
328                                               FilterCCC, CTK_ErrorRecovery,
329                                               LookupCtx)) {
330      Found.setLookupName(Corrected.getCorrection());
331      if (Corrected.getCorrectionDecl())
332        Found.addDecl(Corrected.getCorrectionDecl());
333      FilterAcceptableTemplateNames(Found);
334      if (!Found.empty()) {
335        if (LookupCtx) {
336          std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
337          bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
338                                  Name.getAsString() == CorrectedStr;
339          diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
340                                    << Name << LookupCtx << DroppedSpecifier
341                                    << SS.getRange());
342        } else {
343          diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
344        }
345      }
346    } else {
347      Found.setLookupName(Name);
348    }
349  }
350
351  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
352  if (Found.empty()) {
353    if (isDependent)
354      MemberOfUnknownSpecialization = true;
355    return;
356  }
357
358  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
359      !getLangOpts().CPlusPlus11) {
360    // C++03 [basic.lookup.classref]p1:
361    //   [...] If the lookup in the class of the object expression finds a
362    //   template, the name is also looked up in the context of the entire
363    //   postfix-expression and [...]
364    //
365    // Note: C++11 does not perform this second lookup.
366    LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
367                            LookupOrdinaryName);
368    LookupName(FoundOuter, S);
369    FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
370
371    if (FoundOuter.empty()) {
372      //   - if the name is not found, the name found in the class of the
373      //     object expression is used, otherwise
374    } else if (!FoundOuter.getAsSingle<ClassTemplateDecl>() ||
375               FoundOuter.isAmbiguous()) {
376      //   - if the name is found in the context of the entire
377      //     postfix-expression and does not name a class template, the name
378      //     found in the class of the object expression is used, otherwise
379      FoundOuter.clear();
380    } else if (!Found.isSuppressingDiagnostics()) {
381      //   - if the name found is a class template, it must refer to the same
382      //     entity as the one found in the class of the object expression,
383      //     otherwise the program is ill-formed.
384      if (!Found.isSingleResult() ||
385          Found.getFoundDecl()->getCanonicalDecl()
386            != FoundOuter.getFoundDecl()->getCanonicalDecl()) {
387        Diag(Found.getNameLoc(),
388             diag::ext_nested_name_member_ref_lookup_ambiguous)
389          << Found.getLookupName()
390          << ObjectType;
391        Diag(Found.getRepresentativeDecl()->getLocation(),
392             diag::note_ambig_member_ref_object_type)
393          << ObjectType;
394        Diag(FoundOuter.getFoundDecl()->getLocation(),
395             diag::note_ambig_member_ref_scope);
396
397        // Recover by taking the template that we found in the object
398        // expression's type.
399      }
400    }
401  }
402}
403
404/// ActOnDependentIdExpression - Handle a dependent id-expression that
405/// was just parsed.  This is only possible with an explicit scope
406/// specifier naming a dependent type.
407ExprResult
408Sema::ActOnDependentIdExpression(const CXXScopeSpec &SS,
409                                 SourceLocation TemplateKWLoc,
410                                 const DeclarationNameInfo &NameInfo,
411                                 bool isAddressOfOperand,
412                           const TemplateArgumentListInfo *TemplateArgs) {
413  DeclContext *DC = getFunctionLevelDeclContext();
414
415  if (!isAddressOfOperand &&
416      isa<CXXMethodDecl>(DC) &&
417      cast<CXXMethodDecl>(DC)->isInstance()) {
418    QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
419
420    // Since the 'this' expression is synthesized, we don't need to
421    // perform the double-lookup check.
422    NamedDecl *FirstQualifierInScope = nullptr;
423
424    return CXXDependentScopeMemberExpr::Create(
425        Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
426        /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
427        FirstQualifierInScope, NameInfo, TemplateArgs);
428  }
429
430  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
431}
432
433ExprResult
434Sema::BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
435                                SourceLocation TemplateKWLoc,
436                                const DeclarationNameInfo &NameInfo,
437                                const TemplateArgumentListInfo *TemplateArgs) {
438  return DependentScopeDeclRefExpr::Create(
439      Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
440      TemplateArgs);
441}
442
443/// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
444/// that the template parameter 'PrevDecl' is being shadowed by a new
445/// declaration at location Loc. Returns true to indicate that this is
446/// an error, and false otherwise.
447void Sema::DiagnoseTemplateParameterShadow(SourceLocation Loc, Decl *PrevDecl) {
448  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
449
450  // Microsoft Visual C++ permits template parameters to be shadowed.
451  if (getLangOpts().MicrosoftExt)
452    return;
453
454  // C++ [temp.local]p4:
455  //   A template-parameter shall not be redeclared within its
456  //   scope (including nested scopes).
457  Diag(Loc, diag::err_template_param_shadow)
458    << cast<NamedDecl>(PrevDecl)->getDeclName();
459  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
460  return;
461}
462
463/// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
464/// the parameter D to reference the templated declaration and return a pointer
465/// to the template declaration. Otherwise, do nothing to D and return null.
466TemplateDecl *Sema::AdjustDeclIfTemplate(Decl *&D) {
467  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
468    D = Temp->getTemplatedDecl();
469    return Temp;
470  }
471  return nullptr;
472}
473
474ParsedTemplateArgument ParsedTemplateArgument::getTemplatePackExpansion(
475                                             SourceLocation EllipsisLoc) const {
476  assert(Kind == Template &&
477         "Only template template arguments can be pack expansions here");
478  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
479         "Template template argument pack expansion without packs");
480  ParsedTemplateArgument Result(*this);
481  Result.EllipsisLoc = EllipsisLoc;
482  return Result;
483}
484
485static TemplateArgumentLoc translateTemplateArgument(Sema &SemaRef,
486                                            const ParsedTemplateArgument &Arg) {
487
488  switch (Arg.getKind()) {
489  case ParsedTemplateArgument::Type: {
490    TypeSourceInfo *DI;
491    QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
492    if (!DI)
493      DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
494    return TemplateArgumentLoc(TemplateArgument(T), DI);
495  }
496
497  case ParsedTemplateArgument::NonType: {
498    Expr *E = static_cast<Expr *>(Arg.getAsExpr());
499    return TemplateArgumentLoc(TemplateArgument(E), E);
500  }
501
502  case ParsedTemplateArgument::Template: {
503    TemplateName Template = Arg.getAsTemplate().get();
504    TemplateArgument TArg;
505    if (Arg.getEllipsisLoc().isValid())
506      TArg = TemplateArgument(Template, Optional<unsigned int>());
507    else
508      TArg = Template;
509    return TemplateArgumentLoc(TArg,
510                               Arg.getScopeSpec().getWithLocInContext(
511                                                              SemaRef.Context),
512                               Arg.getLocation(),
513                               Arg.getEllipsisLoc());
514  }
515  }
516
517  llvm_unreachable("Unhandled parsed template argument");
518}
519
520/// \brief Translates template arguments as provided by the parser
521/// into template arguments used by semantic analysis.
522void Sema::translateTemplateArguments(const ASTTemplateArgsPtr &TemplateArgsIn,
523                                      TemplateArgumentListInfo &TemplateArgs) {
524 for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
525   TemplateArgs.addArgument(translateTemplateArgument(*this,
526                                                      TemplateArgsIn[I]));
527}
528
529static void maybeDiagnoseTemplateParameterShadow(Sema &SemaRef, Scope *S,
530                                                 SourceLocation Loc,
531                                                 IdentifierInfo *Name) {
532  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
533      S, Name, Loc, Sema::LookupOrdinaryName, Sema::ForRedeclaration);
534  if (PrevDecl && PrevDecl->isTemplateParameter())
535    SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
536}
537
538/// ActOnTypeParameter - Called when a C++ template type parameter
539/// (e.g., "typename T") has been parsed. Typename specifies whether
540/// the keyword "typename" was used to declare the type parameter
541/// (otherwise, "class" was used), and KeyLoc is the location of the
542/// "class" or "typename" keyword. ParamName is the name of the
543/// parameter (NULL indicates an unnamed template parameter) and
544/// ParamNameLoc is the location of the parameter name (if any).
545/// If the type parameter has a default argument, it will be added
546/// later via ActOnTypeParameterDefault.
547Decl *Sema::ActOnTypeParameter(Scope *S, bool Typename,
548                               SourceLocation EllipsisLoc,
549                               SourceLocation KeyLoc,
550                               IdentifierInfo *ParamName,
551                               SourceLocation ParamNameLoc,
552                               unsigned Depth, unsigned Position,
553                               SourceLocation EqualLoc,
554                               ParsedType DefaultArg) {
555  assert(S->isTemplateParamScope() &&
556         "Template type parameter not in template parameter scope!");
557  bool Invalid = false;
558
559  SourceLocation Loc = ParamNameLoc;
560  if (!ParamName)
561    Loc = KeyLoc;
562
563  bool IsParameterPack = EllipsisLoc.isValid();
564  TemplateTypeParmDecl *Param
565    = TemplateTypeParmDecl::Create(Context, Context.getTranslationUnitDecl(),
566                                   KeyLoc, Loc, Depth, Position, ParamName,
567                                   Typename, IsParameterPack);
568  Param->setAccess(AS_public);
569  if (Invalid)
570    Param->setInvalidDecl();
571
572  if (ParamName) {
573    maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
574
575    // Add the template parameter into the current scope.
576    S->AddDecl(Param);
577    IdResolver.AddDecl(Param);
578  }
579
580  // C++0x [temp.param]p9:
581  //   A default template-argument may be specified for any kind of
582  //   template-parameter that is not a template parameter pack.
583  if (DefaultArg && IsParameterPack) {
584    Diag(EqualLoc, diag::err_template_param_pack_default_arg);
585    DefaultArg = ParsedType();
586  }
587
588  // Handle the default argument, if provided.
589  if (DefaultArg) {
590    TypeSourceInfo *DefaultTInfo;
591    GetTypeFromParser(DefaultArg, &DefaultTInfo);
592
593    assert(DefaultTInfo && "expected source information for type");
594
595    // Check for unexpanded parameter packs.
596    if (DiagnoseUnexpandedParameterPack(Loc, DefaultTInfo,
597                                        UPPC_DefaultArgument))
598      return Param;
599
600    // Check the template argument itself.
601    if (CheckTemplateArgument(Param, DefaultTInfo)) {
602      Param->setInvalidDecl();
603      return Param;
604    }
605
606    Param->setDefaultArgument(DefaultTInfo, false);
607  }
608
609  return Param;
610}
611
612/// \brief Check that the type of a non-type template parameter is
613/// well-formed.
614///
615/// \returns the (possibly-promoted) parameter type if valid;
616/// otherwise, produces a diagnostic and returns a NULL type.
617QualType
618Sema::CheckNonTypeTemplateParameterType(QualType T, SourceLocation Loc) {
619  // We don't allow variably-modified types as the type of non-type template
620  // parameters.
621  if (T->isVariablyModifiedType()) {
622    Diag(Loc, diag::err_variably_modified_nontype_template_param)
623      << T;
624    return QualType();
625  }
626
627  // C++ [temp.param]p4:
628  //
629  // A non-type template-parameter shall have one of the following
630  // (optionally cv-qualified) types:
631  //
632  //       -- integral or enumeration type,
633  if (T->isIntegralOrEnumerationType() ||
634      //   -- pointer to object or pointer to function,
635      T->isPointerType() ||
636      //   -- reference to object or reference to function,
637      T->isReferenceType() ||
638      //   -- pointer to member,
639      T->isMemberPointerType() ||
640      //   -- std::nullptr_t.
641      T->isNullPtrType() ||
642      // If T is a dependent type, we can't do the check now, so we
643      // assume that it is well-formed.
644      T->isDependentType()) {
645    // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
646    // are ignored when determining its type.
647    return T.getUnqualifiedType();
648  }
649
650  // C++ [temp.param]p8:
651  //
652  //   A non-type template-parameter of type "array of T" or
653  //   "function returning T" is adjusted to be of type "pointer to
654  //   T" or "pointer to function returning T", respectively.
655  else if (T->isArrayType())
656    // FIXME: Keep the type prior to promotion?
657    return Context.getArrayDecayedType(T);
658  else if (T->isFunctionType())
659    // FIXME: Keep the type prior to promotion?
660    return Context.getPointerType(T);
661
662  Diag(Loc, diag::err_template_nontype_parm_bad_type)
663    << T;
664
665  return QualType();
666}
667
668Decl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
669                                          unsigned Depth,
670                                          unsigned Position,
671                                          SourceLocation EqualLoc,
672                                          Expr *Default) {
673  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
674  QualType T = TInfo->getType();
675
676  assert(S->isTemplateParamScope() &&
677         "Non-type template parameter not in template parameter scope!");
678  bool Invalid = false;
679
680  T = CheckNonTypeTemplateParameterType(T, D.getIdentifierLoc());
681  if (T.isNull()) {
682    T = Context.IntTy; // Recover with an 'int' type.
683    Invalid = true;
684  }
685
686  IdentifierInfo *ParamName = D.getIdentifier();
687  bool IsParameterPack = D.hasEllipsis();
688  NonTypeTemplateParmDecl *Param
689    = NonTypeTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
690                                      D.getLocStart(),
691                                      D.getIdentifierLoc(),
692                                      Depth, Position, ParamName, T,
693                                      IsParameterPack, TInfo);
694  Param->setAccess(AS_public);
695
696  if (Invalid)
697    Param->setInvalidDecl();
698
699  if (ParamName) {
700    maybeDiagnoseTemplateParameterShadow(*this, S, D.getIdentifierLoc(),
701                                         ParamName);
702
703    // Add the template parameter into the current scope.
704    S->AddDecl(Param);
705    IdResolver.AddDecl(Param);
706  }
707
708  // C++0x [temp.param]p9:
709  //   A default template-argument may be specified for any kind of
710  //   template-parameter that is not a template parameter pack.
711  if (Default && IsParameterPack) {
712    Diag(EqualLoc, diag::err_template_param_pack_default_arg);
713    Default = nullptr;
714  }
715
716  // Check the well-formedness of the default template argument, if provided.
717  if (Default) {
718    // Check for unexpanded parameter packs.
719    if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
720      return Param;
721
722    TemplateArgument Converted;
723    ExprResult DefaultRes = CheckTemplateArgument(Param, Param->getType(), Default, Converted);
724    if (DefaultRes.isInvalid()) {
725      Param->setInvalidDecl();
726      return Param;
727    }
728    Default = DefaultRes.get();
729
730    Param->setDefaultArgument(Default, false);
731  }
732
733  return Param;
734}
735
736/// ActOnTemplateTemplateParameter - Called when a C++ template template
737/// parameter (e.g. T in template <template \<typename> class T> class array)
738/// has been parsed. S is the current scope.
739Decl *Sema::ActOnTemplateTemplateParameter(Scope* S,
740                                           SourceLocation TmpLoc,
741                                           TemplateParameterList *Params,
742                                           SourceLocation EllipsisLoc,
743                                           IdentifierInfo *Name,
744                                           SourceLocation NameLoc,
745                                           unsigned Depth,
746                                           unsigned Position,
747                                           SourceLocation EqualLoc,
748                                           ParsedTemplateArgument Default) {
749  assert(S->isTemplateParamScope() &&
750         "Template template parameter not in template parameter scope!");
751
752  // Construct the parameter object.
753  bool IsParameterPack = EllipsisLoc.isValid();
754  TemplateTemplateParmDecl *Param =
755    TemplateTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
756                                     NameLoc.isInvalid()? TmpLoc : NameLoc,
757                                     Depth, Position, IsParameterPack,
758                                     Name, Params);
759  Param->setAccess(AS_public);
760
761  // If the template template parameter has a name, then link the identifier
762  // into the scope and lookup mechanisms.
763  if (Name) {
764    maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
765
766    S->AddDecl(Param);
767    IdResolver.AddDecl(Param);
768  }
769
770  if (Params->size() == 0) {
771    Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
772    << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
773    Param->setInvalidDecl();
774  }
775
776  // C++0x [temp.param]p9:
777  //   A default template-argument may be specified for any kind of
778  //   template-parameter that is not a template parameter pack.
779  if (IsParameterPack && !Default.isInvalid()) {
780    Diag(EqualLoc, diag::err_template_param_pack_default_arg);
781    Default = ParsedTemplateArgument();
782  }
783
784  if (!Default.isInvalid()) {
785    // Check only that we have a template template argument. We don't want to
786    // try to check well-formedness now, because our template template parameter
787    // might have dependent types in its template parameters, which we wouldn't
788    // be able to match now.
789    //
790    // If none of the template template parameter's template arguments mention
791    // other template parameters, we could actually perform more checking here.
792    // However, it isn't worth doing.
793    TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
794    if (DefaultArg.getArgument().getAsTemplate().isNull()) {
795      Diag(DefaultArg.getLocation(), diag::err_template_arg_not_class_template)
796        << DefaultArg.getSourceRange();
797      return Param;
798    }
799
800    // Check for unexpanded parameter packs.
801    if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
802                                        DefaultArg.getArgument().getAsTemplate(),
803                                        UPPC_DefaultArgument))
804      return Param;
805
806    Param->setDefaultArgument(DefaultArg, false);
807  }
808
809  return Param;
810}
811
812/// ActOnTemplateParameterList - Builds a TemplateParameterList that
813/// contains the template parameters in Params/NumParams.
814TemplateParameterList *
815Sema::ActOnTemplateParameterList(unsigned Depth,
816                                 SourceLocation ExportLoc,
817                                 SourceLocation TemplateLoc,
818                                 SourceLocation LAngleLoc,
819                                 Decl **Params, unsigned NumParams,
820                                 SourceLocation RAngleLoc) {
821  if (ExportLoc.isValid())
822    Diag(ExportLoc, diag::warn_template_export_unsupported);
823
824  return TemplateParameterList::Create(Context, TemplateLoc, LAngleLoc,
825                                       (NamedDecl**)Params, NumParams,
826                                       RAngleLoc);
827}
828
829static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
830  if (SS.isSet())
831    T->setQualifierInfo(SS.getWithLocInContext(T->getASTContext()));
832}
833
834DeclResult
835Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
836                         SourceLocation KWLoc, CXXScopeSpec &SS,
837                         IdentifierInfo *Name, SourceLocation NameLoc,
838                         AttributeList *Attr,
839                         TemplateParameterList *TemplateParams,
840                         AccessSpecifier AS, SourceLocation ModulePrivateLoc,
841                         unsigned NumOuterTemplateParamLists,
842                         TemplateParameterList** OuterTemplateParamLists) {
843  assert(TemplateParams && TemplateParams->size() > 0 &&
844         "No template parameters");
845  assert(TUK != TUK_Reference && "Can only declare or define class templates");
846  bool Invalid = false;
847
848  // Check that we can declare a template here.
849  if (CheckTemplateDeclScope(S, TemplateParams))
850    return true;
851
852  TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
853  assert(Kind != TTK_Enum && "can't build template of enumerated type");
854
855  // There is no such thing as an unnamed class template.
856  if (!Name) {
857    Diag(KWLoc, diag::err_template_unnamed_class);
858    return true;
859  }
860
861  // Find any previous declaration with this name. For a friend with no
862  // scope explicitly specified, we only look for tag declarations (per
863  // C++11 [basic.lookup.elab]p2).
864  DeclContext *SemanticContext;
865  LookupResult Previous(*this, Name, NameLoc,
866                        (SS.isEmpty() && TUK == TUK_Friend)
867                          ? LookupTagName : LookupOrdinaryName,
868                        ForRedeclaration);
869  if (SS.isNotEmpty() && !SS.isInvalid()) {
870    SemanticContext = computeDeclContext(SS, true);
871    if (!SemanticContext) {
872      // FIXME: Horrible, horrible hack! We can't currently represent this
873      // in the AST, and historically we have just ignored such friend
874      // class templates, so don't complain here.
875      Diag(NameLoc, TUK == TUK_Friend
876                        ? diag::warn_template_qualified_friend_ignored
877                        : diag::err_template_qualified_declarator_no_match)
878          << SS.getScopeRep() << SS.getRange();
879      return TUK != TUK_Friend;
880    }
881
882    if (RequireCompleteDeclContext(SS, SemanticContext))
883      return true;
884
885    // If we're adding a template to a dependent context, we may need to
886    // rebuilding some of the types used within the template parameter list,
887    // now that we know what the current instantiation is.
888    if (SemanticContext->isDependentContext()) {
889      ContextRAII SavedContext(*this, SemanticContext);
890      if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
891        Invalid = true;
892    } else if (TUK != TUK_Friend && TUK != TUK_Reference)
893      diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc);
894
895    LookupQualifiedName(Previous, SemanticContext);
896  } else {
897    SemanticContext = CurContext;
898    LookupName(Previous, S);
899  }
900
901  if (Previous.isAmbiguous())
902    return true;
903
904  NamedDecl *PrevDecl = nullptr;
905  if (Previous.begin() != Previous.end())
906    PrevDecl = (*Previous.begin())->getUnderlyingDecl();
907
908  // If there is a previous declaration with the same name, check
909  // whether this is a valid redeclaration.
910  ClassTemplateDecl *PrevClassTemplate
911    = dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
912
913  // We may have found the injected-class-name of a class template,
914  // class template partial specialization, or class template specialization.
915  // In these cases, grab the template that is being defined or specialized.
916  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
917      cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
918    PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
919    PrevClassTemplate
920      = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
921    if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
922      PrevClassTemplate
923        = cast<ClassTemplateSpecializationDecl>(PrevDecl)
924            ->getSpecializedTemplate();
925    }
926  }
927
928  if (TUK == TUK_Friend) {
929    // C++ [namespace.memdef]p3:
930    //   [...] When looking for a prior declaration of a class or a function
931    //   declared as a friend, and when the name of the friend class or
932    //   function is neither a qualified name nor a template-id, scopes outside
933    //   the innermost enclosing namespace scope are not considered.
934    if (!SS.isSet()) {
935      DeclContext *OutermostContext = CurContext;
936      while (!OutermostContext->isFileContext())
937        OutermostContext = OutermostContext->getLookupParent();
938
939      if (PrevDecl &&
940          (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
941           OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
942        SemanticContext = PrevDecl->getDeclContext();
943      } else {
944        // Declarations in outer scopes don't matter. However, the outermost
945        // context we computed is the semantic context for our new
946        // declaration.
947        PrevDecl = PrevClassTemplate = nullptr;
948        SemanticContext = OutermostContext;
949
950        // Check that the chosen semantic context doesn't already contain a
951        // declaration of this name as a non-tag type.
952        LookupResult Previous(*this, Name, NameLoc, LookupOrdinaryName,
953                              ForRedeclaration);
954        DeclContext *LookupContext = SemanticContext;
955        while (LookupContext->isTransparentContext())
956          LookupContext = LookupContext->getLookupParent();
957        LookupQualifiedName(Previous, LookupContext);
958
959        if (Previous.isAmbiguous())
960          return true;
961
962        if (Previous.begin() != Previous.end())
963          PrevDecl = (*Previous.begin())->getUnderlyingDecl();
964      }
965    }
966  } else if (PrevDecl &&
967             !isDeclInScope(PrevDecl, SemanticContext, S, SS.isValid()))
968    PrevDecl = PrevClassTemplate = nullptr;
969
970  if (PrevClassTemplate) {
971    // Ensure that the template parameter lists are compatible. Skip this check
972    // for a friend in a dependent context: the template parameter list itself
973    // could be dependent.
974    if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
975        !TemplateParameterListsAreEqual(TemplateParams,
976                                   PrevClassTemplate->getTemplateParameters(),
977                                        /*Complain=*/true,
978                                        TPL_TemplateMatch))
979      return true;
980
981    // C++ [temp.class]p4:
982    //   In a redeclaration, partial specialization, explicit
983    //   specialization or explicit instantiation of a class template,
984    //   the class-key shall agree in kind with the original class
985    //   template declaration (7.1.5.3).
986    RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
987    if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
988                                      TUK == TUK_Definition,  KWLoc, *Name)) {
989      Diag(KWLoc, diag::err_use_with_wrong_tag)
990        << Name
991        << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
992      Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
993      Kind = PrevRecordDecl->getTagKind();
994    }
995
996    // Check for redefinition of this class template.
997    if (TUK == TUK_Definition) {
998      if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
999        Diag(NameLoc, diag::err_redefinition) << Name;
1000        Diag(Def->getLocation(), diag::note_previous_definition);
1001        // FIXME: Would it make sense to try to "forget" the previous
1002        // definition, as part of error recovery?
1003        return true;
1004      }
1005    }
1006  } else if (PrevDecl && PrevDecl->isTemplateParameter()) {
1007    // Maybe we will complain about the shadowed template parameter.
1008    DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1009    // Just pretend that we didn't see the previous declaration.
1010    PrevDecl = nullptr;
1011  } else if (PrevDecl) {
1012    // C++ [temp]p5:
1013    //   A class template shall not have the same name as any other
1014    //   template, class, function, object, enumeration, enumerator,
1015    //   namespace, or type in the same scope (3.3), except as specified
1016    //   in (14.5.4).
1017    Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1018    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1019    return true;
1020  }
1021
1022  // Check the template parameter list of this declaration, possibly
1023  // merging in the template parameter list from the previous class
1024  // template declaration. Skip this check for a friend in a dependent
1025  // context, because the template parameter list might be dependent.
1026  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1027      CheckTemplateParameterList(
1028          TemplateParams,
1029          PrevClassTemplate ? PrevClassTemplate->getTemplateParameters()
1030                            : nullptr,
1031          (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1032           SemanticContext->isDependentContext())
1033              ? TPC_ClassTemplateMember
1034              : TUK == TUK_Friend ? TPC_FriendClassTemplate
1035                                  : TPC_ClassTemplate))
1036    Invalid = true;
1037
1038  if (SS.isSet()) {
1039    // If the name of the template was qualified, we must be defining the
1040    // template out-of-line.
1041    if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1042      Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1043                                      : diag::err_member_decl_does_not_match)
1044        << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1045      Invalid = true;
1046    }
1047  }
1048
1049  CXXRecordDecl *NewClass =
1050    CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1051                          PrevClassTemplate?
1052                            PrevClassTemplate->getTemplatedDecl() : nullptr,
1053                          /*DelayTypeCreation=*/true);
1054  SetNestedNameSpecifier(NewClass, SS);
1055  if (NumOuterTemplateParamLists > 0)
1056    NewClass->setTemplateParameterListsInfo(Context,
1057                                            NumOuterTemplateParamLists,
1058                                            OuterTemplateParamLists);
1059
1060  // Add alignment attributes if necessary; these attributes are checked when
1061  // the ASTContext lays out the structure.
1062  if (TUK == TUK_Definition) {
1063    AddAlignmentAttributesForRecord(NewClass);
1064    AddMsStructLayoutForRecord(NewClass);
1065  }
1066
1067  ClassTemplateDecl *NewTemplate
1068    = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1069                                DeclarationName(Name), TemplateParams,
1070                                NewClass, PrevClassTemplate);
1071  NewClass->setDescribedClassTemplate(NewTemplate);
1072
1073  if (ModulePrivateLoc.isValid())
1074    NewTemplate->setModulePrivate();
1075
1076  // Build the type for the class template declaration now.
1077  QualType T = NewTemplate->getInjectedClassNameSpecialization();
1078  T = Context.getInjectedClassNameType(NewClass, T);
1079  assert(T->isDependentType() && "Class template type is not dependent?");
1080  (void)T;
1081
1082  // If we are providing an explicit specialization of a member that is a
1083  // class template, make a note of that.
1084  if (PrevClassTemplate &&
1085      PrevClassTemplate->getInstantiatedFromMemberTemplate())
1086    PrevClassTemplate->setMemberSpecialization();
1087
1088  // Set the access specifier.
1089  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1090    SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1091
1092  // Set the lexical context of these templates
1093  NewClass->setLexicalDeclContext(CurContext);
1094  NewTemplate->setLexicalDeclContext(CurContext);
1095
1096  if (TUK == TUK_Definition)
1097    NewClass->startDefinition();
1098
1099  if (Attr)
1100    ProcessDeclAttributeList(S, NewClass, Attr);
1101
1102  if (PrevClassTemplate)
1103    mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1104
1105  AddPushedVisibilityAttribute(NewClass);
1106
1107  if (TUK != TUK_Friend)
1108    PushOnScopeChains(NewTemplate, S);
1109  else {
1110    if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1111      NewTemplate->setAccess(PrevClassTemplate->getAccess());
1112      NewClass->setAccess(PrevClassTemplate->getAccess());
1113    }
1114
1115    NewTemplate->setObjectOfFriendDecl();
1116
1117    // Friend templates are visible in fairly strange ways.
1118    if (!CurContext->isDependentContext()) {
1119      DeclContext *DC = SemanticContext->getRedeclContext();
1120      DC->makeDeclVisibleInContext(NewTemplate);
1121      if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1122        PushOnScopeChains(NewTemplate, EnclosingScope,
1123                          /* AddToContext = */ false);
1124    }
1125
1126    FriendDecl *Friend = FriendDecl::Create(Context, CurContext,
1127                                            NewClass->getLocation(),
1128                                            NewTemplate,
1129                                    /*FIXME:*/NewClass->getLocation());
1130    Friend->setAccess(AS_public);
1131    CurContext->addDecl(Friend);
1132  }
1133
1134  if (Invalid) {
1135    NewTemplate->setInvalidDecl();
1136    NewClass->setInvalidDecl();
1137  }
1138
1139  ActOnDocumentableDecl(NewTemplate);
1140
1141  return NewTemplate;
1142}
1143
1144/// \brief Diagnose the presence of a default template argument on a
1145/// template parameter, which is ill-formed in certain contexts.
1146///
1147/// \returns true if the default template argument should be dropped.
1148static bool DiagnoseDefaultTemplateArgument(Sema &S,
1149                                            Sema::TemplateParamListContext TPC,
1150                                            SourceLocation ParamLoc,
1151                                            SourceRange DefArgRange) {
1152  switch (TPC) {
1153  case Sema::TPC_ClassTemplate:
1154  case Sema::TPC_VarTemplate:
1155  case Sema::TPC_TypeAliasTemplate:
1156    return false;
1157
1158  case Sema::TPC_FunctionTemplate:
1159  case Sema::TPC_FriendFunctionTemplateDefinition:
1160    // C++ [temp.param]p9:
1161    //   A default template-argument shall not be specified in a
1162    //   function template declaration or a function template
1163    //   definition [...]
1164    //   If a friend function template declaration specifies a default
1165    //   template-argument, that declaration shall be a definition and shall be
1166    //   the only declaration of the function template in the translation unit.
1167    // (C++98/03 doesn't have this wording; see DR226).
1168    S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
1169         diag::warn_cxx98_compat_template_parameter_default_in_function_template
1170           : diag::ext_template_parameter_default_in_function_template)
1171      << DefArgRange;
1172    return false;
1173
1174  case Sema::TPC_ClassTemplateMember:
1175    // C++0x [temp.param]p9:
1176    //   A default template-argument shall not be specified in the
1177    //   template-parameter-lists of the definition of a member of a
1178    //   class template that appears outside of the member's class.
1179    S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
1180      << DefArgRange;
1181    return true;
1182
1183  case Sema::TPC_FriendClassTemplate:
1184  case Sema::TPC_FriendFunctionTemplate:
1185    // C++ [temp.param]p9:
1186    //   A default template-argument shall not be specified in a
1187    //   friend template declaration.
1188    S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
1189      << DefArgRange;
1190    return true;
1191
1192    // FIXME: C++0x [temp.param]p9 allows default template-arguments
1193    // for friend function templates if there is only a single
1194    // declaration (and it is a definition). Strange!
1195  }
1196
1197  llvm_unreachable("Invalid TemplateParamListContext!");
1198}
1199
1200/// \brief Check for unexpanded parameter packs within the template parameters
1201/// of a template template parameter, recursively.
1202static bool DiagnoseUnexpandedParameterPacks(Sema &S,
1203                                             TemplateTemplateParmDecl *TTP) {
1204  // A template template parameter which is a parameter pack is also a pack
1205  // expansion.
1206  if (TTP->isParameterPack())
1207    return false;
1208
1209  TemplateParameterList *Params = TTP->getTemplateParameters();
1210  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
1211    NamedDecl *P = Params->getParam(I);
1212    if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
1213      if (!NTTP->isParameterPack() &&
1214          S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
1215                                            NTTP->getTypeSourceInfo(),
1216                                      Sema::UPPC_NonTypeTemplateParameterType))
1217        return true;
1218
1219      continue;
1220    }
1221
1222    if (TemplateTemplateParmDecl *InnerTTP
1223                                        = dyn_cast<TemplateTemplateParmDecl>(P))
1224      if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
1225        return true;
1226  }
1227
1228  return false;
1229}
1230
1231/// \brief Checks the validity of a template parameter list, possibly
1232/// considering the template parameter list from a previous
1233/// declaration.
1234///
1235/// If an "old" template parameter list is provided, it must be
1236/// equivalent (per TemplateParameterListsAreEqual) to the "new"
1237/// template parameter list.
1238///
1239/// \param NewParams Template parameter list for a new template
1240/// declaration. This template parameter list will be updated with any
1241/// default arguments that are carried through from the previous
1242/// template parameter list.
1243///
1244/// \param OldParams If provided, template parameter list from a
1245/// previous declaration of the same template. Default template
1246/// arguments will be merged from the old template parameter list to
1247/// the new template parameter list.
1248///
1249/// \param TPC Describes the context in which we are checking the given
1250/// template parameter list.
1251///
1252/// \returns true if an error occurred, false otherwise.
1253bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
1254                                      TemplateParameterList *OldParams,
1255                                      TemplateParamListContext TPC) {
1256  bool Invalid = false;
1257
1258  // C++ [temp.param]p10:
1259  //   The set of default template-arguments available for use with a
1260  //   template declaration or definition is obtained by merging the
1261  //   default arguments from the definition (if in scope) and all
1262  //   declarations in scope in the same way default function
1263  //   arguments are (8.3.6).
1264  bool SawDefaultArgument = false;
1265  SourceLocation PreviousDefaultArgLoc;
1266
1267  // Dummy initialization to avoid warnings.
1268  TemplateParameterList::iterator OldParam = NewParams->end();
1269  if (OldParams)
1270    OldParam = OldParams->begin();
1271
1272  bool RemoveDefaultArguments = false;
1273  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
1274                                    NewParamEnd = NewParams->end();
1275       NewParam != NewParamEnd; ++NewParam) {
1276    // Variables used to diagnose redundant default arguments
1277    bool RedundantDefaultArg = false;
1278    SourceLocation OldDefaultLoc;
1279    SourceLocation NewDefaultLoc;
1280
1281    // Variable used to diagnose missing default arguments
1282    bool MissingDefaultArg = false;
1283
1284    // Variable used to diagnose non-final parameter packs
1285    bool SawParameterPack = false;
1286
1287    if (TemplateTypeParmDecl *NewTypeParm
1288          = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
1289      // Check the presence of a default argument here.
1290      if (NewTypeParm->hasDefaultArgument() &&
1291          DiagnoseDefaultTemplateArgument(*this, TPC,
1292                                          NewTypeParm->getLocation(),
1293               NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
1294                                                       .getSourceRange()))
1295        NewTypeParm->removeDefaultArgument();
1296
1297      // Merge default arguments for template type parameters.
1298      TemplateTypeParmDecl *OldTypeParm
1299          = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
1300
1301      if (NewTypeParm->isParameterPack()) {
1302        assert(!NewTypeParm->hasDefaultArgument() &&
1303               "Parameter packs can't have a default argument!");
1304        SawParameterPack = true;
1305      } else if (OldTypeParm && OldTypeParm->hasDefaultArgument() &&
1306                 NewTypeParm->hasDefaultArgument()) {
1307        OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
1308        NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
1309        SawDefaultArgument = true;
1310        RedundantDefaultArg = true;
1311        PreviousDefaultArgLoc = NewDefaultLoc;
1312      } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
1313        // Merge the default argument from the old declaration to the
1314        // new declaration.
1315        NewTypeParm->setDefaultArgument(OldTypeParm->getDefaultArgumentInfo(),
1316                                        true);
1317        PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
1318      } else if (NewTypeParm->hasDefaultArgument()) {
1319        SawDefaultArgument = true;
1320        PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
1321      } else if (SawDefaultArgument)
1322        MissingDefaultArg = true;
1323    } else if (NonTypeTemplateParmDecl *NewNonTypeParm
1324               = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
1325      // Check for unexpanded parameter packs.
1326      if (!NewNonTypeParm->isParameterPack() &&
1327          DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
1328                                          NewNonTypeParm->getTypeSourceInfo(),
1329                                          UPPC_NonTypeTemplateParameterType)) {
1330        Invalid = true;
1331        continue;
1332      }
1333
1334      // Check the presence of a default argument here.
1335      if (NewNonTypeParm->hasDefaultArgument() &&
1336          DiagnoseDefaultTemplateArgument(*this, TPC,
1337                                          NewNonTypeParm->getLocation(),
1338                    NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
1339        NewNonTypeParm->removeDefaultArgument();
1340      }
1341
1342      // Merge default arguments for non-type template parameters
1343      NonTypeTemplateParmDecl *OldNonTypeParm
1344        = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
1345      if (NewNonTypeParm->isParameterPack()) {
1346        assert(!NewNonTypeParm->hasDefaultArgument() &&
1347               "Parameter packs can't have a default argument!");
1348        if (!NewNonTypeParm->isPackExpansion())
1349          SawParameterPack = true;
1350      } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument() &&
1351                 NewNonTypeParm->hasDefaultArgument()) {
1352        OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
1353        NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
1354        SawDefaultArgument = true;
1355        RedundantDefaultArg = true;
1356        PreviousDefaultArgLoc = NewDefaultLoc;
1357      } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
1358        // Merge the default argument from the old declaration to the
1359        // new declaration.
1360        // FIXME: We need to create a new kind of "default argument"
1361        // expression that points to a previous non-type template
1362        // parameter.
1363        NewNonTypeParm->setDefaultArgument(
1364                                         OldNonTypeParm->getDefaultArgument(),
1365                                         /*Inherited=*/ true);
1366        PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
1367      } else if (NewNonTypeParm->hasDefaultArgument()) {
1368        SawDefaultArgument = true;
1369        PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
1370      } else if (SawDefaultArgument)
1371        MissingDefaultArg = true;
1372    } else {
1373      TemplateTemplateParmDecl *NewTemplateParm
1374        = cast<TemplateTemplateParmDecl>(*NewParam);
1375
1376      // Check for unexpanded parameter packs, recursively.
1377      if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
1378        Invalid = true;
1379        continue;
1380      }
1381
1382      // Check the presence of a default argument here.
1383      if (NewTemplateParm->hasDefaultArgument() &&
1384          DiagnoseDefaultTemplateArgument(*this, TPC,
1385                                          NewTemplateParm->getLocation(),
1386                     NewTemplateParm->getDefaultArgument().getSourceRange()))
1387        NewTemplateParm->removeDefaultArgument();
1388
1389      // Merge default arguments for template template parameters
1390      TemplateTemplateParmDecl *OldTemplateParm
1391        = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
1392      if (NewTemplateParm->isParameterPack()) {
1393        assert(!NewTemplateParm->hasDefaultArgument() &&
1394               "Parameter packs can't have a default argument!");
1395        if (!NewTemplateParm->isPackExpansion())
1396          SawParameterPack = true;
1397      } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument() &&
1398          NewTemplateParm->hasDefaultArgument()) {
1399        OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
1400        NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
1401        SawDefaultArgument = true;
1402        RedundantDefaultArg = true;
1403        PreviousDefaultArgLoc = NewDefaultLoc;
1404      } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
1405        // Merge the default argument from the old declaration to the
1406        // new declaration.
1407        // FIXME: We need to create a new kind of "default argument" expression
1408        // that points to a previous template template parameter.
1409        NewTemplateParm->setDefaultArgument(
1410                                          OldTemplateParm->getDefaultArgument(),
1411                                          /*Inherited=*/ true);
1412        PreviousDefaultArgLoc
1413          = OldTemplateParm->getDefaultArgument().getLocation();
1414      } else if (NewTemplateParm->hasDefaultArgument()) {
1415        SawDefaultArgument = true;
1416        PreviousDefaultArgLoc
1417          = NewTemplateParm->getDefaultArgument().getLocation();
1418      } else if (SawDefaultArgument)
1419        MissingDefaultArg = true;
1420    }
1421
1422    // C++11 [temp.param]p11:
1423    //   If a template parameter of a primary class template or alias template
1424    //   is a template parameter pack, it shall be the last template parameter.
1425    if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
1426        (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
1427         TPC == TPC_TypeAliasTemplate)) {
1428      Diag((*NewParam)->getLocation(),
1429           diag::err_template_param_pack_must_be_last_template_parameter);
1430      Invalid = true;
1431    }
1432
1433    if (RedundantDefaultArg) {
1434      // C++ [temp.param]p12:
1435      //   A template-parameter shall not be given default arguments
1436      //   by two different declarations in the same scope.
1437      Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
1438      Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
1439      Invalid = true;
1440    } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
1441      // C++ [temp.param]p11:
1442      //   If a template-parameter of a class template has a default
1443      //   template-argument, each subsequent template-parameter shall either
1444      //   have a default template-argument supplied or be a template parameter
1445      //   pack.
1446      Diag((*NewParam)->getLocation(),
1447           diag::err_template_param_default_arg_missing);
1448      Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
1449      Invalid = true;
1450      RemoveDefaultArguments = true;
1451    }
1452
1453    // If we have an old template parameter list that we're merging
1454    // in, move on to the next parameter.
1455    if (OldParams)
1456      ++OldParam;
1457  }
1458
1459  // We were missing some default arguments at the end of the list, so remove
1460  // all of the default arguments.
1461  if (RemoveDefaultArguments) {
1462    for (TemplateParameterList::iterator NewParam = NewParams->begin(),
1463                                      NewParamEnd = NewParams->end();
1464         NewParam != NewParamEnd; ++NewParam) {
1465      if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
1466        TTP->removeDefaultArgument();
1467      else if (NonTypeTemplateParmDecl *NTTP
1468                                = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
1469        NTTP->removeDefaultArgument();
1470      else
1471        cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
1472    }
1473  }
1474
1475  return Invalid;
1476}
1477
1478namespace {
1479
1480/// A class which looks for a use of a certain level of template
1481/// parameter.
1482struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
1483  typedef RecursiveASTVisitor<DependencyChecker> super;
1484
1485  unsigned Depth;
1486  bool Match;
1487  SourceLocation MatchLoc;
1488
1489  DependencyChecker(unsigned Depth) : Depth(Depth), Match(false) {}
1490
1491  DependencyChecker(TemplateParameterList *Params) : Match(false) {
1492    NamedDecl *ND = Params->getParam(0);
1493    if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
1494      Depth = PD->getDepth();
1495    } else if (NonTypeTemplateParmDecl *PD =
1496                 dyn_cast<NonTypeTemplateParmDecl>(ND)) {
1497      Depth = PD->getDepth();
1498    } else {
1499      Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
1500    }
1501  }
1502
1503  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
1504    if (ParmDepth >= Depth) {
1505      Match = true;
1506      MatchLoc = Loc;
1507      return true;
1508    }
1509    return false;
1510  }
1511
1512  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
1513    return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
1514  }
1515
1516  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
1517    return !Matches(T->getDepth());
1518  }
1519
1520  bool TraverseTemplateName(TemplateName N) {
1521    if (TemplateTemplateParmDecl *PD =
1522          dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
1523      if (Matches(PD->getDepth()))
1524        return false;
1525    return super::TraverseTemplateName(N);
1526  }
1527
1528  bool VisitDeclRefExpr(DeclRefExpr *E) {
1529    if (NonTypeTemplateParmDecl *PD =
1530          dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
1531      if (Matches(PD->getDepth(), E->getExprLoc()))
1532        return false;
1533    return super::VisitDeclRefExpr(E);
1534  }
1535
1536  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
1537    return TraverseType(T->getReplacementType());
1538  }
1539
1540  bool
1541  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
1542    return TraverseTemplateArgument(T->getArgumentPack());
1543  }
1544
1545  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
1546    return TraverseType(T->getInjectedSpecializationType());
1547  }
1548};
1549}
1550
1551/// Determines whether a given type depends on the given parameter
1552/// list.
1553static bool
1554DependsOnTemplateParameters(QualType T, TemplateParameterList *Params) {
1555  DependencyChecker Checker(Params);
1556  Checker.TraverseType(T);
1557  return Checker.Match;
1558}
1559
1560// Find the source range corresponding to the named type in the given
1561// nested-name-specifier, if any.
1562static SourceRange getRangeOfTypeInNestedNameSpecifier(ASTContext &Context,
1563                                                       QualType T,
1564                                                       const CXXScopeSpec &SS) {
1565  NestedNameSpecifierLoc NNSLoc(SS.getScopeRep(), SS.location_data());
1566  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
1567    if (const Type *CurType = NNS->getAsType()) {
1568      if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
1569        return NNSLoc.getTypeLoc().getSourceRange();
1570    } else
1571      break;
1572
1573    NNSLoc = NNSLoc.getPrefix();
1574  }
1575
1576  return SourceRange();
1577}
1578
1579/// \brief Match the given template parameter lists to the given scope
1580/// specifier, returning the template parameter list that applies to the
1581/// name.
1582///
1583/// \param DeclStartLoc the start of the declaration that has a scope
1584/// specifier or a template parameter list.
1585///
1586/// \param DeclLoc The location of the declaration itself.
1587///
1588/// \param SS the scope specifier that will be matched to the given template
1589/// parameter lists. This scope specifier precedes a qualified name that is
1590/// being declared.
1591///
1592/// \param TemplateId The template-id following the scope specifier, if there
1593/// is one. Used to check for a missing 'template<>'.
1594///
1595/// \param ParamLists the template parameter lists, from the outermost to the
1596/// innermost template parameter lists.
1597///
1598/// \param IsFriend Whether to apply the slightly different rules for
1599/// matching template parameters to scope specifiers in friend
1600/// declarations.
1601///
1602/// \param IsExplicitSpecialization will be set true if the entity being
1603/// declared is an explicit specialization, false otherwise.
1604///
1605/// \returns the template parameter list, if any, that corresponds to the
1606/// name that is preceded by the scope specifier @p SS. This template
1607/// parameter list may have template parameters (if we're declaring a
1608/// template) or may have no template parameters (if we're declaring a
1609/// template specialization), or may be NULL (if what we're declaring isn't
1610/// itself a template).
1611TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
1612    SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
1613    TemplateIdAnnotation *TemplateId,
1614    ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
1615    bool &IsExplicitSpecialization, bool &Invalid) {
1616  IsExplicitSpecialization = false;
1617  Invalid = false;
1618
1619  // The sequence of nested types to which we will match up the template
1620  // parameter lists. We first build this list by starting with the type named
1621  // by the nested-name-specifier and walking out until we run out of types.
1622  SmallVector<QualType, 4> NestedTypes;
1623  QualType T;
1624  if (SS.getScopeRep()) {
1625    if (CXXRecordDecl *Record
1626              = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
1627      T = Context.getTypeDeclType(Record);
1628    else
1629      T = QualType(SS.getScopeRep()->getAsType(), 0);
1630  }
1631
1632  // If we found an explicit specialization that prevents us from needing
1633  // 'template<>' headers, this will be set to the location of that
1634  // explicit specialization.
1635  SourceLocation ExplicitSpecLoc;
1636
1637  while (!T.isNull()) {
1638    NestedTypes.push_back(T);
1639
1640    // Retrieve the parent of a record type.
1641    if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
1642      // If this type is an explicit specialization, we're done.
1643      if (ClassTemplateSpecializationDecl *Spec
1644          = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
1645        if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
1646            Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
1647          ExplicitSpecLoc = Spec->getLocation();
1648          break;
1649        }
1650      } else if (Record->getTemplateSpecializationKind()
1651                                                == TSK_ExplicitSpecialization) {
1652        ExplicitSpecLoc = Record->getLocation();
1653        break;
1654      }
1655
1656      if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
1657        T = Context.getTypeDeclType(Parent);
1658      else
1659        T = QualType();
1660      continue;
1661    }
1662
1663    if (const TemplateSpecializationType *TST
1664                                     = T->getAs<TemplateSpecializationType>()) {
1665      if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
1666        if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
1667          T = Context.getTypeDeclType(Parent);
1668        else
1669          T = QualType();
1670        continue;
1671      }
1672    }
1673
1674    // Look one step prior in a dependent template specialization type.
1675    if (const DependentTemplateSpecializationType *DependentTST
1676                          = T->getAs<DependentTemplateSpecializationType>()) {
1677      if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
1678        T = QualType(NNS->getAsType(), 0);
1679      else
1680        T = QualType();
1681      continue;
1682    }
1683
1684    // Look one step prior in a dependent name type.
1685    if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
1686      if (NestedNameSpecifier *NNS = DependentName->getQualifier())
1687        T = QualType(NNS->getAsType(), 0);
1688      else
1689        T = QualType();
1690      continue;
1691    }
1692
1693    // Retrieve the parent of an enumeration type.
1694    if (const EnumType *EnumT = T->getAs<EnumType>()) {
1695      // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
1696      // check here.
1697      EnumDecl *Enum = EnumT->getDecl();
1698
1699      // Get to the parent type.
1700      if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
1701        T = Context.getTypeDeclType(Parent);
1702      else
1703        T = QualType();
1704      continue;
1705    }
1706
1707    T = QualType();
1708  }
1709  // Reverse the nested types list, since we want to traverse from the outermost
1710  // to the innermost while checking template-parameter-lists.
1711  std::reverse(NestedTypes.begin(), NestedTypes.end());
1712
1713  // C++0x [temp.expl.spec]p17:
1714  //   A member or a member template may be nested within many
1715  //   enclosing class templates. In an explicit specialization for
1716  //   such a member, the member declaration shall be preceded by a
1717  //   template<> for each enclosing class template that is
1718  //   explicitly specialized.
1719  bool SawNonEmptyTemplateParameterList = false;
1720
1721  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
1722    if (SawNonEmptyTemplateParameterList) {
1723      Diag(DeclLoc, diag::err_specialize_member_of_template)
1724        << !Recovery << Range;
1725      Invalid = true;
1726      IsExplicitSpecialization = false;
1727      return true;
1728    }
1729
1730    return false;
1731  };
1732
1733  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
1734    // Check that we can have an explicit specialization here.
1735    if (CheckExplicitSpecialization(Range, true))
1736      return true;
1737
1738    // We don't have a template header, but we should.
1739    SourceLocation ExpectedTemplateLoc;
1740    if (!ParamLists.empty())
1741      ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
1742    else
1743      ExpectedTemplateLoc = DeclStartLoc;
1744
1745    Diag(DeclLoc, diag::err_template_spec_needs_header)
1746      << Range
1747      << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
1748    return false;
1749  };
1750
1751  unsigned ParamIdx = 0;
1752  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
1753       ++TypeIdx) {
1754    T = NestedTypes[TypeIdx];
1755
1756    // Whether we expect a 'template<>' header.
1757    bool NeedEmptyTemplateHeader = false;
1758
1759    // Whether we expect a template header with parameters.
1760    bool NeedNonemptyTemplateHeader = false;
1761
1762    // For a dependent type, the set of template parameters that we
1763    // expect to see.
1764    TemplateParameterList *ExpectedTemplateParams = nullptr;
1765
1766    // C++0x [temp.expl.spec]p15:
1767    //   A member or a member template may be nested within many enclosing
1768    //   class templates. In an explicit specialization for such a member, the
1769    //   member declaration shall be preceded by a template<> for each
1770    //   enclosing class template that is explicitly specialized.
1771    if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
1772      if (ClassTemplatePartialSpecializationDecl *Partial
1773            = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
1774        ExpectedTemplateParams = Partial->getTemplateParameters();
1775        NeedNonemptyTemplateHeader = true;
1776      } else if (Record->isDependentType()) {
1777        if (Record->getDescribedClassTemplate()) {
1778          ExpectedTemplateParams = Record->getDescribedClassTemplate()
1779                                                      ->getTemplateParameters();
1780          NeedNonemptyTemplateHeader = true;
1781        }
1782      } else if (ClassTemplateSpecializationDecl *Spec
1783                     = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
1784        // C++0x [temp.expl.spec]p4:
1785        //   Members of an explicitly specialized class template are defined
1786        //   in the same manner as members of normal classes, and not using
1787        //   the template<> syntax.
1788        if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
1789          NeedEmptyTemplateHeader = true;
1790        else
1791          continue;
1792      } else if (Record->getTemplateSpecializationKind()) {
1793        if (Record->getTemplateSpecializationKind()
1794                                                != TSK_ExplicitSpecialization &&
1795            TypeIdx == NumTypes - 1)
1796          IsExplicitSpecialization = true;
1797
1798        continue;
1799      }
1800    } else if (const TemplateSpecializationType *TST
1801                                     = T->getAs<TemplateSpecializationType>()) {
1802      if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
1803        ExpectedTemplateParams = Template->getTemplateParameters();
1804        NeedNonemptyTemplateHeader = true;
1805      }
1806    } else if (T->getAs<DependentTemplateSpecializationType>()) {
1807      // FIXME:  We actually could/should check the template arguments here
1808      // against the corresponding template parameter list.
1809      NeedNonemptyTemplateHeader = false;
1810    }
1811
1812    // C++ [temp.expl.spec]p16:
1813    //   In an explicit specialization declaration for a member of a class
1814    //   template or a member template that ap- pears in namespace scope, the
1815    //   member template and some of its enclosing class templates may remain
1816    //   unspecialized, except that the declaration shall not explicitly
1817    //   specialize a class member template if its en- closing class templates
1818    //   are not explicitly specialized as well.
1819    if (ParamIdx < ParamLists.size()) {
1820      if (ParamLists[ParamIdx]->size() == 0) {
1821        if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
1822                                        false))
1823          return nullptr;
1824      } else
1825        SawNonEmptyTemplateParameterList = true;
1826    }
1827
1828    if (NeedEmptyTemplateHeader) {
1829      // If we're on the last of the types, and we need a 'template<>' header
1830      // here, then it's an explicit specialization.
1831      if (TypeIdx == NumTypes - 1)
1832        IsExplicitSpecialization = true;
1833
1834      if (ParamIdx < ParamLists.size()) {
1835        if (ParamLists[ParamIdx]->size() > 0) {
1836          // The header has template parameters when it shouldn't. Complain.
1837          Diag(ParamLists[ParamIdx]->getTemplateLoc(),
1838               diag::err_template_param_list_matches_nontemplate)
1839            << T
1840            << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
1841                           ParamLists[ParamIdx]->getRAngleLoc())
1842            << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
1843          Invalid = true;
1844          return nullptr;
1845        }
1846
1847        // Consume this template header.
1848        ++ParamIdx;
1849        continue;
1850      }
1851
1852      if (!IsFriend)
1853        if (DiagnoseMissingExplicitSpecialization(
1854                getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
1855          return nullptr;
1856
1857      continue;
1858    }
1859
1860    if (NeedNonemptyTemplateHeader) {
1861      // In friend declarations we can have template-ids which don't
1862      // depend on the corresponding template parameter lists.  But
1863      // assume that empty parameter lists are supposed to match this
1864      // template-id.
1865      if (IsFriend && T->isDependentType()) {
1866        if (ParamIdx < ParamLists.size() &&
1867            DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
1868          ExpectedTemplateParams = nullptr;
1869        else
1870          continue;
1871      }
1872
1873      if (ParamIdx < ParamLists.size()) {
1874        // Check the template parameter list, if we can.
1875        if (ExpectedTemplateParams &&
1876            !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
1877                                            ExpectedTemplateParams,
1878                                            true, TPL_TemplateMatch))
1879          Invalid = true;
1880
1881        if (!Invalid &&
1882            CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
1883                                       TPC_ClassTemplateMember))
1884          Invalid = true;
1885
1886        ++ParamIdx;
1887        continue;
1888      }
1889
1890      Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
1891        << T
1892        << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
1893      Invalid = true;
1894      continue;
1895    }
1896  }
1897
1898  // If there were at least as many template-ids as there were template
1899  // parameter lists, then there are no template parameter lists remaining for
1900  // the declaration itself.
1901  if (ParamIdx >= ParamLists.size()) {
1902    if (TemplateId && !IsFriend) {
1903      // We don't have a template header for the declaration itself, but we
1904      // should.
1905      IsExplicitSpecialization = true;
1906      DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
1907                                                        TemplateId->RAngleLoc));
1908
1909      // Fabricate an empty template parameter list for the invented header.
1910      return TemplateParameterList::Create(Context, SourceLocation(),
1911                                           SourceLocation(), nullptr, 0,
1912                                           SourceLocation());
1913    }
1914
1915    return nullptr;
1916  }
1917
1918  // If there were too many template parameter lists, complain about that now.
1919  if (ParamIdx < ParamLists.size() - 1) {
1920    bool HasAnyExplicitSpecHeader = false;
1921    bool AllExplicitSpecHeaders = true;
1922    for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
1923      if (ParamLists[I]->size() == 0)
1924        HasAnyExplicitSpecHeader = true;
1925      else
1926        AllExplicitSpecHeaders = false;
1927    }
1928
1929    Diag(ParamLists[ParamIdx]->getTemplateLoc(),
1930         AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
1931                                : diag::err_template_spec_extra_headers)
1932        << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
1933                       ParamLists[ParamLists.size() - 2]->getRAngleLoc());
1934
1935    // If there was a specialization somewhere, such that 'template<>' is
1936    // not required, and there were any 'template<>' headers, note where the
1937    // specialization occurred.
1938    if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
1939      Diag(ExplicitSpecLoc,
1940           diag::note_explicit_template_spec_does_not_need_header)
1941        << NestedTypes.back();
1942
1943    // We have a template parameter list with no corresponding scope, which
1944    // means that the resulting template declaration can't be instantiated
1945    // properly (we'll end up with dependent nodes when we shouldn't).
1946    if (!AllExplicitSpecHeaders)
1947      Invalid = true;
1948  }
1949
1950  // C++ [temp.expl.spec]p16:
1951  //   In an explicit specialization declaration for a member of a class
1952  //   template or a member template that ap- pears in namespace scope, the
1953  //   member template and some of its enclosing class templates may remain
1954  //   unspecialized, except that the declaration shall not explicitly
1955  //   specialize a class member template if its en- closing class templates
1956  //   are not explicitly specialized as well.
1957  if (ParamLists.back()->size() == 0 &&
1958      CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
1959                                  false))
1960    return nullptr;
1961
1962  // Return the last template parameter list, which corresponds to the
1963  // entity being declared.
1964  return ParamLists.back();
1965}
1966
1967void Sema::NoteAllFoundTemplates(TemplateName Name) {
1968  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
1969    Diag(Template->getLocation(), diag::note_template_declared_here)
1970        << (isa<FunctionTemplateDecl>(Template)
1971                ? 0
1972                : isa<ClassTemplateDecl>(Template)
1973                      ? 1
1974                      : isa<VarTemplateDecl>(Template)
1975                            ? 2
1976                            : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
1977        << Template->getDeclName();
1978    return;
1979  }
1980
1981  if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
1982    for (OverloadedTemplateStorage::iterator I = OST->begin(),
1983                                          IEnd = OST->end();
1984         I != IEnd; ++I)
1985      Diag((*I)->getLocation(), diag::note_template_declared_here)
1986        << 0 << (*I)->getDeclName();
1987
1988    return;
1989  }
1990}
1991
1992QualType Sema::CheckTemplateIdType(TemplateName Name,
1993                                   SourceLocation TemplateLoc,
1994                                   TemplateArgumentListInfo &TemplateArgs) {
1995  DependentTemplateName *DTN
1996    = Name.getUnderlying().getAsDependentTemplateName();
1997  if (DTN && DTN->isIdentifier())
1998    // When building a template-id where the template-name is dependent,
1999    // assume the template is a type template. Either our assumption is
2000    // correct, or the code is ill-formed and will be diagnosed when the
2001    // dependent name is substituted.
2002    return Context.getDependentTemplateSpecializationType(ETK_None,
2003                                                          DTN->getQualifier(),
2004                                                          DTN->getIdentifier(),
2005                                                          TemplateArgs);
2006
2007  TemplateDecl *Template = Name.getAsTemplateDecl();
2008  if (!Template || isa<FunctionTemplateDecl>(Template) ||
2009      isa<VarTemplateDecl>(Template)) {
2010    // We might have a substituted template template parameter pack. If so,
2011    // build a template specialization type for it.
2012    if (Name.getAsSubstTemplateTemplateParmPack())
2013      return Context.getTemplateSpecializationType(Name, TemplateArgs);
2014
2015    Diag(TemplateLoc, diag::err_template_id_not_a_type)
2016      << Name;
2017    NoteAllFoundTemplates(Name);
2018    return QualType();
2019  }
2020
2021  // Check that the template argument list is well-formed for this
2022  // template.
2023  SmallVector<TemplateArgument, 4> Converted;
2024  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
2025                                false, Converted))
2026    return QualType();
2027
2028  QualType CanonType;
2029
2030  bool InstantiationDependent = false;
2031  if (TypeAliasTemplateDecl *AliasTemplate =
2032          dyn_cast<TypeAliasTemplateDecl>(Template)) {
2033    // Find the canonical type for this type alias template specialization.
2034    TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
2035    if (Pattern->isInvalidDecl())
2036      return QualType();
2037
2038    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2039                                      Converted.data(), Converted.size());
2040
2041    // Only substitute for the innermost template argument list.
2042    MultiLevelTemplateArgumentList TemplateArgLists;
2043    TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
2044    unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
2045    for (unsigned I = 0; I < Depth; ++I)
2046      TemplateArgLists.addOuterTemplateArguments(None);
2047
2048    LocalInstantiationScope Scope(*this);
2049    InstantiatingTemplate Inst(*this, TemplateLoc, Template);
2050    if (Inst.isInvalid())
2051      return QualType();
2052
2053    CanonType = SubstType(Pattern->getUnderlyingType(),
2054                          TemplateArgLists, AliasTemplate->getLocation(),
2055                          AliasTemplate->getDeclName());
2056    if (CanonType.isNull())
2057      return QualType();
2058  } else if (Name.isDependent() ||
2059             TemplateSpecializationType::anyDependentTemplateArguments(
2060               TemplateArgs, InstantiationDependent)) {
2061    // This class template specialization is a dependent
2062    // type. Therefore, its canonical type is another class template
2063    // specialization type that contains all of the converted
2064    // arguments in canonical form. This ensures that, e.g., A<T> and
2065    // A<T, T> have identical types when A is declared as:
2066    //
2067    //   template<typename T, typename U = T> struct A;
2068    TemplateName CanonName = Context.getCanonicalTemplateName(Name);
2069    CanonType = Context.getTemplateSpecializationType(CanonName,
2070                                                      Converted.data(),
2071                                                      Converted.size());
2072
2073    // FIXME: CanonType is not actually the canonical type, and unfortunately
2074    // it is a TemplateSpecializationType that we will never use again.
2075    // In the future, we need to teach getTemplateSpecializationType to only
2076    // build the canonical type and return that to us.
2077    CanonType = Context.getCanonicalType(CanonType);
2078
2079    // This might work out to be a current instantiation, in which
2080    // case the canonical type needs to be the InjectedClassNameType.
2081    //
2082    // TODO: in theory this could be a simple hashtable lookup; most
2083    // changes to CurContext don't change the set of current
2084    // instantiations.
2085    if (isa<ClassTemplateDecl>(Template)) {
2086      for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
2087        // If we get out to a namespace, we're done.
2088        if (Ctx->isFileContext()) break;
2089
2090        // If this isn't a record, keep looking.
2091        CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
2092        if (!Record) continue;
2093
2094        // Look for one of the two cases with InjectedClassNameTypes
2095        // and check whether it's the same template.
2096        if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
2097            !Record->getDescribedClassTemplate())
2098          continue;
2099
2100        // Fetch the injected class name type and check whether its
2101        // injected type is equal to the type we just built.
2102        QualType ICNT = Context.getTypeDeclType(Record);
2103        QualType Injected = cast<InjectedClassNameType>(ICNT)
2104          ->getInjectedSpecializationType();
2105
2106        if (CanonType != Injected->getCanonicalTypeInternal())
2107          continue;
2108
2109        // If so, the canonical type of this TST is the injected
2110        // class name type of the record we just found.
2111        assert(ICNT.isCanonical());
2112        CanonType = ICNT;
2113        break;
2114      }
2115    }
2116  } else if (ClassTemplateDecl *ClassTemplate
2117               = dyn_cast<ClassTemplateDecl>(Template)) {
2118    // Find the class template specialization declaration that
2119    // corresponds to these arguments.
2120    void *InsertPos = nullptr;
2121    ClassTemplateSpecializationDecl *Decl
2122      = ClassTemplate->findSpecialization(Converted, InsertPos);
2123    if (!Decl) {
2124      // This is the first time we have referenced this class template
2125      // specialization. Create the canonical declaration and add it to
2126      // the set of specializations.
2127      Decl = ClassTemplateSpecializationDecl::Create(Context,
2128                            ClassTemplate->getTemplatedDecl()->getTagKind(),
2129                                                ClassTemplate->getDeclContext(),
2130                            ClassTemplate->getTemplatedDecl()->getLocStart(),
2131                                                ClassTemplate->getLocation(),
2132                                                     ClassTemplate,
2133                                                     Converted.data(),
2134                                                     Converted.size(), nullptr);
2135      ClassTemplate->AddSpecialization(Decl, InsertPos);
2136      if (ClassTemplate->isOutOfLine())
2137        Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
2138    }
2139
2140    // Diagnose uses of this specialization.
2141    (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
2142
2143    CanonType = Context.getTypeDeclType(Decl);
2144    assert(isa<RecordType>(CanonType) &&
2145           "type of non-dependent specialization is not a RecordType");
2146  }
2147
2148  // Build the fully-sugared type for this class template
2149  // specialization, which refers back to the class template
2150  // specialization we created or found.
2151  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
2152}
2153
2154TypeResult
2155Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
2156                          TemplateTy TemplateD, SourceLocation TemplateLoc,
2157                          SourceLocation LAngleLoc,
2158                          ASTTemplateArgsPtr TemplateArgsIn,
2159                          SourceLocation RAngleLoc,
2160                          bool IsCtorOrDtorName) {
2161  if (SS.isInvalid())
2162    return true;
2163
2164  TemplateName Template = TemplateD.get();
2165
2166  // Translate the parser's template argument list in our AST format.
2167  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
2168  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
2169
2170  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
2171    QualType T
2172      = Context.getDependentTemplateSpecializationType(ETK_None,
2173                                                       DTN->getQualifier(),
2174                                                       DTN->getIdentifier(),
2175                                                       TemplateArgs);
2176    // Build type-source information.
2177    TypeLocBuilder TLB;
2178    DependentTemplateSpecializationTypeLoc SpecTL
2179      = TLB.push<DependentTemplateSpecializationTypeLoc>(T);
2180    SpecTL.setElaboratedKeywordLoc(SourceLocation());
2181    SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
2182    SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2183    SpecTL.setTemplateNameLoc(TemplateLoc);
2184    SpecTL.setLAngleLoc(LAngleLoc);
2185    SpecTL.setRAngleLoc(RAngleLoc);
2186    for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
2187      SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
2188    return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
2189  }
2190
2191  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
2192
2193  if (Result.isNull())
2194    return true;
2195
2196  // Build type-source information.
2197  TypeLocBuilder TLB;
2198  TemplateSpecializationTypeLoc SpecTL
2199    = TLB.push<TemplateSpecializationTypeLoc>(Result);
2200  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2201  SpecTL.setTemplateNameLoc(TemplateLoc);
2202  SpecTL.setLAngleLoc(LAngleLoc);
2203  SpecTL.setRAngleLoc(RAngleLoc);
2204  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
2205    SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
2206
2207  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
2208  // constructor or destructor name (in such a case, the scope specifier
2209  // will be attached to the enclosing Decl or Expr node).
2210  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
2211    // Create an elaborated-type-specifier containing the nested-name-specifier.
2212    Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
2213    ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
2214    ElabTL.setElaboratedKeywordLoc(SourceLocation());
2215    ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
2216  }
2217
2218  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
2219}
2220
2221TypeResult Sema::ActOnTagTemplateIdType(TagUseKind TUK,
2222                                        TypeSpecifierType TagSpec,
2223                                        SourceLocation TagLoc,
2224                                        CXXScopeSpec &SS,
2225                                        SourceLocation TemplateKWLoc,
2226                                        TemplateTy TemplateD,
2227                                        SourceLocation TemplateLoc,
2228                                        SourceLocation LAngleLoc,
2229                                        ASTTemplateArgsPtr TemplateArgsIn,
2230                                        SourceLocation RAngleLoc) {
2231  TemplateName Template = TemplateD.get();
2232
2233  // Translate the parser's template argument list in our AST format.
2234  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
2235  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
2236
2237  // Determine the tag kind
2238  TagTypeKind TagKind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
2239  ElaboratedTypeKeyword Keyword
2240    = TypeWithKeyword::getKeywordForTagTypeKind(TagKind);
2241
2242  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
2243    QualType T = Context.getDependentTemplateSpecializationType(Keyword,
2244                                                          DTN->getQualifier(),
2245                                                          DTN->getIdentifier(),
2246                                                                TemplateArgs);
2247
2248    // Build type-source information.
2249    TypeLocBuilder TLB;
2250    DependentTemplateSpecializationTypeLoc SpecTL
2251      = TLB.push<DependentTemplateSpecializationTypeLoc>(T);
2252    SpecTL.setElaboratedKeywordLoc(TagLoc);
2253    SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
2254    SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2255    SpecTL.setTemplateNameLoc(TemplateLoc);
2256    SpecTL.setLAngleLoc(LAngleLoc);
2257    SpecTL.setRAngleLoc(RAngleLoc);
2258    for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
2259      SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
2260    return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
2261  }
2262
2263  if (TypeAliasTemplateDecl *TAT =
2264        dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
2265    // C++0x [dcl.type.elab]p2:
2266    //   If the identifier resolves to a typedef-name or the simple-template-id
2267    //   resolves to an alias template specialization, the
2268    //   elaborated-type-specifier is ill-formed.
2269    Diag(TemplateLoc, diag::err_tag_reference_non_tag) << 4;
2270    Diag(TAT->getLocation(), diag::note_declared_at);
2271  }
2272
2273  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
2274  if (Result.isNull())
2275    return TypeResult(true);
2276
2277  // Check the tag kind
2278  if (const RecordType *RT = Result->getAs<RecordType>()) {
2279    RecordDecl *D = RT->getDecl();
2280
2281    IdentifierInfo *Id = D->getIdentifier();
2282    assert(Id && "templated class must have an identifier");
2283
2284    if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
2285                                      TagLoc, *Id)) {
2286      Diag(TagLoc, diag::err_use_with_wrong_tag)
2287        << Result
2288        << FixItHint::CreateReplacement(SourceRange(TagLoc), D->getKindName());
2289      Diag(D->getLocation(), diag::note_previous_use);
2290    }
2291  }
2292
2293  // Provide source-location information for the template specialization.
2294  TypeLocBuilder TLB;
2295  TemplateSpecializationTypeLoc SpecTL
2296    = TLB.push<TemplateSpecializationTypeLoc>(Result);
2297  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2298  SpecTL.setTemplateNameLoc(TemplateLoc);
2299  SpecTL.setLAngleLoc(LAngleLoc);
2300  SpecTL.setRAngleLoc(RAngleLoc);
2301  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
2302    SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
2303
2304  // Construct an elaborated type containing the nested-name-specifier (if any)
2305  // and tag keyword.
2306  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
2307  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
2308  ElabTL.setElaboratedKeywordLoc(TagLoc);
2309  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
2310  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
2311}
2312
2313static bool CheckTemplatePartialSpecializationArgs(
2314    Sema &S, SourceLocation NameLoc, TemplateParameterList *TemplateParams,
2315    unsigned ExplicitArgs, SmallVectorImpl<TemplateArgument> &TemplateArgs);
2316
2317static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
2318                                             NamedDecl *PrevDecl,
2319                                             SourceLocation Loc,
2320                                             bool IsPartialSpecialization);
2321
2322static TemplateSpecializationKind getTemplateSpecializationKind(Decl *D);
2323
2324static bool isTemplateArgumentTemplateParameter(
2325    const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
2326  switch (Arg.getKind()) {
2327  case TemplateArgument::Null:
2328  case TemplateArgument::NullPtr:
2329  case TemplateArgument::Integral:
2330  case TemplateArgument::Declaration:
2331  case TemplateArgument::Pack:
2332  case TemplateArgument::TemplateExpansion:
2333    return false;
2334
2335  case TemplateArgument::Type: {
2336    QualType Type = Arg.getAsType();
2337    const TemplateTypeParmType *TPT =
2338        Arg.getAsType()->getAs<TemplateTypeParmType>();
2339    return TPT && !Type.hasQualifiers() &&
2340           TPT->getDepth() == Depth && TPT->getIndex() == Index;
2341  }
2342
2343  case TemplateArgument::Expression: {
2344    DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
2345    if (!DRE || !DRE->getDecl())
2346      return false;
2347    const NonTypeTemplateParmDecl *NTTP =
2348        dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
2349    return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
2350  }
2351
2352  case TemplateArgument::Template:
2353    const TemplateTemplateParmDecl *TTP =
2354        dyn_cast_or_null<TemplateTemplateParmDecl>(
2355            Arg.getAsTemplateOrTemplatePattern().getAsTemplateDecl());
2356    return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
2357  }
2358  llvm_unreachable("unexpected kind of template argument");
2359}
2360
2361static bool isSameAsPrimaryTemplate(TemplateParameterList *Params,
2362                                    ArrayRef<TemplateArgument> Args) {
2363  if (Params->size() != Args.size())
2364    return false;
2365
2366  unsigned Depth = Params->getDepth();
2367
2368  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2369    TemplateArgument Arg = Args[I];
2370
2371    // If the parameter is a pack expansion, the argument must be a pack
2372    // whose only element is a pack expansion.
2373    if (Params->getParam(I)->isParameterPack()) {
2374      if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
2375          !Arg.pack_begin()->isPackExpansion())
2376        return false;
2377      Arg = Arg.pack_begin()->getPackExpansionPattern();
2378    }
2379
2380    if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
2381      return false;
2382  }
2383
2384  return true;
2385}
2386
2387/// Convert the parser's template argument list representation into our form.
2388static TemplateArgumentListInfo
2389makeTemplateArgumentListInfo(Sema &S, TemplateIdAnnotation &TemplateId) {
2390  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
2391                                        TemplateId.RAngleLoc);
2392  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
2393                                     TemplateId.NumArgs);
2394  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
2395  return TemplateArgs;
2396}
2397
2398DeclResult Sema::ActOnVarTemplateSpecialization(
2399    Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
2400    TemplateParameterList *TemplateParams, VarDecl::StorageClass SC,
2401    bool IsPartialSpecialization) {
2402  // D must be variable template id.
2403  assert(D.getName().getKind() == UnqualifiedId::IK_TemplateId &&
2404         "Variable template specialization is declared with a template it.");
2405
2406  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
2407  TemplateArgumentListInfo TemplateArgs =
2408      makeTemplateArgumentListInfo(*this, *TemplateId);
2409  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
2410  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
2411  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
2412
2413  TemplateName Name = TemplateId->Template.get();
2414
2415  // The template-id must name a variable template.
2416  VarTemplateDecl *VarTemplate =
2417      dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
2418  if (!VarTemplate) {
2419    NamedDecl *FnTemplate;
2420    if (auto *OTS = Name.getAsOverloadedTemplate())
2421      FnTemplate = *OTS->begin();
2422    else
2423      FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
2424    if (FnTemplate)
2425      return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
2426               << FnTemplate->getDeclName();
2427    return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
2428             << IsPartialSpecialization;
2429  }
2430
2431  // Check for unexpanded parameter packs in any of the template arguments.
2432  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
2433    if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
2434                                        UPPC_PartialSpecialization))
2435      return true;
2436
2437  // Check that the template argument list is well-formed for this
2438  // template.
2439  SmallVector<TemplateArgument, 4> Converted;
2440  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
2441                                false, Converted))
2442    return true;
2443
2444  // Check that the type of this variable template specialization
2445  // matches the expected type.
2446  TypeSourceInfo *ExpectedDI;
2447  {
2448    // Do substitution on the type of the declaration
2449    TemplateArgumentList TemplateArgList(TemplateArgumentList::OnStack,
2450                                         Converted.data(), Converted.size());
2451    InstantiatingTemplate Inst(*this, TemplateKWLoc, VarTemplate);
2452    if (Inst.isInvalid())
2453      return true;
2454    VarDecl *Templated = VarTemplate->getTemplatedDecl();
2455    ExpectedDI =
2456        SubstType(Templated->getTypeSourceInfo(),
2457                  MultiLevelTemplateArgumentList(TemplateArgList),
2458                  Templated->getTypeSpecStartLoc(), Templated->getDeclName());
2459  }
2460  if (!ExpectedDI)
2461    return true;
2462
2463  // Find the variable template (partial) specialization declaration that
2464  // corresponds to these arguments.
2465  if (IsPartialSpecialization) {
2466    if (CheckTemplatePartialSpecializationArgs(
2467            *this, TemplateNameLoc, VarTemplate->getTemplateParameters(),
2468            TemplateArgs.size(), Converted))
2469      return true;
2470
2471    bool InstantiationDependent;
2472    if (!Name.isDependent() &&
2473        !TemplateSpecializationType::anyDependentTemplateArguments(
2474            TemplateArgs.getArgumentArray(), TemplateArgs.size(),
2475            InstantiationDependent)) {
2476      Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
2477          << VarTemplate->getDeclName();
2478      IsPartialSpecialization = false;
2479    }
2480
2481    if (isSameAsPrimaryTemplate(VarTemplate->getTemplateParameters(),
2482                                Converted)) {
2483      // C++ [temp.class.spec]p9b3:
2484      //
2485      //   -- The argument list of the specialization shall not be identical
2486      //      to the implicit argument list of the primary template.
2487      Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
2488        << /*variable template*/ 1
2489        << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
2490        << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
2491      // FIXME: Recover from this by treating the declaration as a redeclaration
2492      // of the primary template.
2493      return true;
2494    }
2495  }
2496
2497  void *InsertPos = nullptr;
2498  VarTemplateSpecializationDecl *PrevDecl = nullptr;
2499
2500  if (IsPartialSpecialization)
2501    // FIXME: Template parameter list matters too
2502    PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
2503  else
2504    PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
2505
2506  VarTemplateSpecializationDecl *Specialization = nullptr;
2507
2508  // Check whether we can declare a variable template specialization in
2509  // the current scope.
2510  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
2511                                       TemplateNameLoc,
2512                                       IsPartialSpecialization))
2513    return true;
2514
2515  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
2516    // Since the only prior variable template specialization with these
2517    // arguments was referenced but not declared,  reuse that
2518    // declaration node as our own, updating its source location and
2519    // the list of outer template parameters to reflect our new declaration.
2520    Specialization = PrevDecl;
2521    Specialization->setLocation(TemplateNameLoc);
2522    PrevDecl = nullptr;
2523  } else if (IsPartialSpecialization) {
2524    // Create a new class template partial specialization declaration node.
2525    VarTemplatePartialSpecializationDecl *PrevPartial =
2526        cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
2527    VarTemplatePartialSpecializationDecl *Partial =
2528        VarTemplatePartialSpecializationDecl::Create(
2529            Context, VarTemplate->getDeclContext(), TemplateKWLoc,
2530            TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
2531            Converted.data(), Converted.size(), TemplateArgs);
2532
2533    if (!PrevPartial)
2534      VarTemplate->AddPartialSpecialization(Partial, InsertPos);
2535    Specialization = Partial;
2536
2537    // If we are providing an explicit specialization of a member variable
2538    // template specialization, make a note of that.
2539    if (PrevPartial && PrevPartial->getInstantiatedFromMember())
2540      PrevPartial->setMemberSpecialization();
2541
2542    // Check that all of the template parameters of the variable template
2543    // partial specialization are deducible from the template
2544    // arguments. If not, this variable template partial specialization
2545    // will never be used.
2546    llvm::SmallBitVector DeducibleParams(TemplateParams->size());
2547    MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
2548                               TemplateParams->getDepth(), DeducibleParams);
2549
2550    if (!DeducibleParams.all()) {
2551      unsigned NumNonDeducible =
2552          DeducibleParams.size() - DeducibleParams.count();
2553      Diag(TemplateNameLoc, diag::warn_partial_specs_not_deducible)
2554        << /*variable template*/ 1 << (NumNonDeducible > 1)
2555        << SourceRange(TemplateNameLoc, RAngleLoc);
2556      for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
2557        if (!DeducibleParams[I]) {
2558          NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
2559          if (Param->getDeclName())
2560            Diag(Param->getLocation(), diag::note_partial_spec_unused_parameter)
2561                << Param->getDeclName();
2562          else
2563            Diag(Param->getLocation(), diag::note_partial_spec_unused_parameter)
2564                << "(anonymous)";
2565        }
2566      }
2567    }
2568  } else {
2569    // Create a new class template specialization declaration node for
2570    // this explicit specialization or friend declaration.
2571    Specialization = VarTemplateSpecializationDecl::Create(
2572        Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
2573        VarTemplate, DI->getType(), DI, SC, Converted.data(), Converted.size());
2574    Specialization->setTemplateArgsInfo(TemplateArgs);
2575
2576    if (!PrevDecl)
2577      VarTemplate->AddSpecialization(Specialization, InsertPos);
2578  }
2579
2580  // C++ [temp.expl.spec]p6:
2581  //   If a template, a member template or the member of a class template is
2582  //   explicitly specialized then that specialization shall be declared
2583  //   before the first use of that specialization that would cause an implicit
2584  //   instantiation to take place, in every translation unit in which such a
2585  //   use occurs; no diagnostic is required.
2586  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
2587    bool Okay = false;
2588    for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
2589      // Is there any previous explicit specialization declaration?
2590      if (getTemplateSpecializationKind(Prev) == TSK_ExplicitSpecialization) {
2591        Okay = true;
2592        break;
2593      }
2594    }
2595
2596    if (!Okay) {
2597      SourceRange Range(TemplateNameLoc, RAngleLoc);
2598      Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
2599          << Name << Range;
2600
2601      Diag(PrevDecl->getPointOfInstantiation(),
2602           diag::note_instantiation_required_here)
2603          << (PrevDecl->getTemplateSpecializationKind() !=
2604              TSK_ImplicitInstantiation);
2605      return true;
2606    }
2607  }
2608
2609  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
2610  Specialization->setLexicalDeclContext(CurContext);
2611
2612  // Add the specialization into its lexical context, so that it can
2613  // be seen when iterating through the list of declarations in that
2614  // context. However, specializations are not found by name lookup.
2615  CurContext->addDecl(Specialization);
2616
2617  // Note that this is an explicit specialization.
2618  Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
2619
2620  if (PrevDecl) {
2621    // Check that this isn't a redefinition of this specialization,
2622    // merging with previous declarations.
2623    LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
2624                          ForRedeclaration);
2625    PrevSpec.addDecl(PrevDecl);
2626    D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
2627  } else if (Specialization->isStaticDataMember() &&
2628             Specialization->isOutOfLine()) {
2629    Specialization->setAccess(VarTemplate->getAccess());
2630  }
2631
2632  // Link instantiations of static data members back to the template from
2633  // which they were instantiated.
2634  if (Specialization->isStaticDataMember())
2635    Specialization->setInstantiationOfStaticDataMember(
2636        VarTemplate->getTemplatedDecl(),
2637        Specialization->getSpecializationKind());
2638
2639  return Specialization;
2640}
2641
2642namespace {
2643/// \brief A partial specialization whose template arguments have matched
2644/// a given template-id.
2645struct PartialSpecMatchResult {
2646  VarTemplatePartialSpecializationDecl *Partial;
2647  TemplateArgumentList *Args;
2648};
2649}
2650
2651DeclResult
2652Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
2653                         SourceLocation TemplateNameLoc,
2654                         const TemplateArgumentListInfo &TemplateArgs) {
2655  assert(Template && "A variable template id without template?");
2656
2657  // Check that the template argument list is well-formed for this template.
2658  SmallVector<TemplateArgument, 4> Converted;
2659  if (CheckTemplateArgumentList(
2660          Template, TemplateNameLoc,
2661          const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
2662          Converted))
2663    return true;
2664
2665  // Find the variable template specialization declaration that
2666  // corresponds to these arguments.
2667  void *InsertPos = nullptr;
2668  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
2669          Converted, InsertPos))
2670    // If we already have a variable template specialization, return it.
2671    return Spec;
2672
2673  // This is the first time we have referenced this variable template
2674  // specialization. Create the canonical declaration and add it to
2675  // the set of specializations, based on the closest partial specialization
2676  // that it represents. That is,
2677  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
2678  TemplateArgumentList TemplateArgList(TemplateArgumentList::OnStack,
2679                                       Converted.data(), Converted.size());
2680  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
2681  bool AmbiguousPartialSpec = false;
2682  typedef PartialSpecMatchResult MatchResult;
2683  SmallVector<MatchResult, 4> Matched;
2684  SourceLocation PointOfInstantiation = TemplateNameLoc;
2685  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation);
2686
2687  // 1. Attempt to find the closest partial specialization that this
2688  // specializes, if any.
2689  // If any of the template arguments is dependent, then this is probably
2690  // a placeholder for an incomplete declarative context; which must be
2691  // complete by instantiation time. Thus, do not search through the partial
2692  // specializations yet.
2693  // TODO: Unify with InstantiateClassTemplateSpecialization()?
2694  //       Perhaps better after unification of DeduceTemplateArguments() and
2695  //       getMoreSpecializedPartialSpecialization().
2696  bool InstantiationDependent = false;
2697  if (!TemplateSpecializationType::anyDependentTemplateArguments(
2698          TemplateArgs, InstantiationDependent)) {
2699
2700    SmallVector<VarTemplatePartialSpecializationDecl *, 4> PartialSpecs;
2701    Template->getPartialSpecializations(PartialSpecs);
2702
2703    for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
2704      VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
2705      TemplateDeductionInfo Info(FailedCandidates.getLocation());
2706
2707      if (TemplateDeductionResult Result =
2708              DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
2709        // Store the failed-deduction information for use in diagnostics, later.
2710        // TODO: Actually use the failed-deduction info?
2711        FailedCandidates.addCandidate()
2712            .set(Partial, MakeDeductionFailureInfo(Context, Result, Info));
2713        (void)Result;
2714      } else {
2715        Matched.push_back(PartialSpecMatchResult());
2716        Matched.back().Partial = Partial;
2717        Matched.back().Args = Info.take();
2718      }
2719    }
2720
2721    if (Matched.size() >= 1) {
2722      SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
2723      if (Matched.size() == 1) {
2724        //   -- If exactly one matching specialization is found, the
2725        //      instantiation is generated from that specialization.
2726        // We don't need to do anything for this.
2727      } else {
2728        //   -- If more than one matching specialization is found, the
2729        //      partial order rules (14.5.4.2) are used to determine
2730        //      whether one of the specializations is more specialized
2731        //      than the others. If none of the specializations is more
2732        //      specialized than all of the other matching
2733        //      specializations, then the use of the variable template is
2734        //      ambiguous and the program is ill-formed.
2735        for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
2736                                                   PEnd = Matched.end();
2737             P != PEnd; ++P) {
2738          if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
2739                                                      PointOfInstantiation) ==
2740              P->Partial)
2741            Best = P;
2742        }
2743
2744        // Determine if the best partial specialization is more specialized than
2745        // the others.
2746        for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2747                                                   PEnd = Matched.end();
2748             P != PEnd; ++P) {
2749          if (P != Best && getMoreSpecializedPartialSpecialization(
2750                               P->Partial, Best->Partial,
2751                               PointOfInstantiation) != Best->Partial) {
2752            AmbiguousPartialSpec = true;
2753            break;
2754          }
2755        }
2756      }
2757
2758      // Instantiate using the best variable template partial specialization.
2759      InstantiationPattern = Best->Partial;
2760      InstantiationArgs = Best->Args;
2761    } else {
2762      //   -- If no match is found, the instantiation is generated
2763      //      from the primary template.
2764      // InstantiationPattern = Template->getTemplatedDecl();
2765    }
2766  }
2767
2768  // 2. Create the canonical declaration.
2769  // Note that we do not instantiate the variable just yet, since
2770  // instantiation is handled in DoMarkVarDeclReferenced().
2771  // FIXME: LateAttrs et al.?
2772  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
2773      Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
2774      Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
2775  if (!Decl)
2776    return true;
2777
2778  if (AmbiguousPartialSpec) {
2779    // Partial ordering did not produce a clear winner. Complain.
2780    Decl->setInvalidDecl();
2781    Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
2782        << Decl;
2783
2784    // Print the matching partial specializations.
2785    for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2786                                               PEnd = Matched.end();
2787         P != PEnd; ++P)
2788      Diag(P->Partial->getLocation(), diag::note_partial_spec_match)
2789          << getTemplateArgumentBindingsText(
2790                 P->Partial->getTemplateParameters(), *P->Args);
2791    return true;
2792  }
2793
2794  if (VarTemplatePartialSpecializationDecl *D =
2795          dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
2796    Decl->setInstantiationOf(D, InstantiationArgs);
2797
2798  assert(Decl && "No variable template specialization?");
2799  return Decl;
2800}
2801
2802ExprResult
2803Sema::CheckVarTemplateId(const CXXScopeSpec &SS,
2804                         const DeclarationNameInfo &NameInfo,
2805                         VarTemplateDecl *Template, SourceLocation TemplateLoc,
2806                         const TemplateArgumentListInfo *TemplateArgs) {
2807
2808  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
2809                                       *TemplateArgs);
2810  if (Decl.isInvalid())
2811    return ExprError();
2812
2813  VarDecl *Var = cast<VarDecl>(Decl.get());
2814  if (!Var->getTemplateSpecializationKind())
2815    Var->setTemplateSpecializationKind(TSK_ImplicitInstantiation,
2816                                       NameInfo.getLoc());
2817
2818  // Build an ordinary singleton decl ref.
2819  return BuildDeclarationNameExpr(SS, NameInfo, Var,
2820                                  /*FoundD=*/nullptr, TemplateArgs);
2821}
2822
2823ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
2824                                     SourceLocation TemplateKWLoc,
2825                                     LookupResult &R,
2826                                     bool RequiresADL,
2827                                 const TemplateArgumentListInfo *TemplateArgs) {
2828  // FIXME: Can we do any checking at this point? I guess we could check the
2829  // template arguments that we have against the template name, if the template
2830  // name refers to a single template. That's not a terribly common case,
2831  // though.
2832  // foo<int> could identify a single function unambiguously
2833  // This approach does NOT work, since f<int>(1);
2834  // gets resolved prior to resorting to overload resolution
2835  // i.e., template<class T> void f(double);
2836  //       vs template<class T, class U> void f(U);
2837
2838  // These should be filtered out by our callers.
2839  assert(!R.empty() && "empty lookup results when building templateid");
2840  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
2841
2842  // In C++1y, check variable template ids.
2843  bool InstantiationDependent;
2844  if (R.getAsSingle<VarTemplateDecl>() &&
2845      !TemplateSpecializationType::anyDependentTemplateArguments(
2846           *TemplateArgs, InstantiationDependent)) {
2847    return CheckVarTemplateId(SS, R.getLookupNameInfo(),
2848                              R.getAsSingle<VarTemplateDecl>(),
2849                              TemplateKWLoc, TemplateArgs);
2850  }
2851
2852  // We don't want lookup warnings at this point.
2853  R.suppressDiagnostics();
2854
2855  UnresolvedLookupExpr *ULE
2856    = UnresolvedLookupExpr::Create(Context, R.getNamingClass(),
2857                                   SS.getWithLocInContext(Context),
2858                                   TemplateKWLoc,
2859                                   R.getLookupNameInfo(),
2860                                   RequiresADL, TemplateArgs,
2861                                   R.begin(), R.end());
2862
2863  return ULE;
2864}
2865
2866// We actually only call this from template instantiation.
2867ExprResult
2868Sema::BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
2869                                   SourceLocation TemplateKWLoc,
2870                                   const DeclarationNameInfo &NameInfo,
2871                             const TemplateArgumentListInfo *TemplateArgs) {
2872
2873  assert(TemplateArgs || TemplateKWLoc.isValid());
2874  DeclContext *DC;
2875  if (!(DC = computeDeclContext(SS, false)) ||
2876      DC->isDependentContext() ||
2877      RequireCompleteDeclContext(SS, DC))
2878    return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
2879
2880  bool MemberOfUnknownSpecialization;
2881  LookupResult R(*this, NameInfo, LookupOrdinaryName);
2882  LookupTemplateName(R, (Scope*)nullptr, SS, QualType(), /*Entering*/ false,
2883                     MemberOfUnknownSpecialization);
2884
2885  if (R.isAmbiguous())
2886    return ExprError();
2887
2888  if (R.empty()) {
2889    Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_non_template)
2890      << NameInfo.getName() << SS.getRange();
2891    return ExprError();
2892  }
2893
2894  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
2895    Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
2896      << SS.getScopeRep()
2897      << NameInfo.getName().getAsString() << SS.getRange();
2898    Diag(Temp->getLocation(), diag::note_referenced_class_template);
2899    return ExprError();
2900  }
2901
2902  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
2903}
2904
2905/// \brief Form a dependent template name.
2906///
2907/// This action forms a dependent template name given the template
2908/// name and its (presumably dependent) scope specifier. For
2909/// example, given "MetaFun::template apply", the scope specifier \p
2910/// SS will be "MetaFun::", \p TemplateKWLoc contains the location
2911/// of the "template" keyword, and "apply" is the \p Name.
2912TemplateNameKind Sema::ActOnDependentTemplateName(Scope *S,
2913                                                  CXXScopeSpec &SS,
2914                                                  SourceLocation TemplateKWLoc,
2915                                                  UnqualifiedId &Name,
2916                                                  ParsedType ObjectType,
2917                                                  bool EnteringContext,
2918                                                  TemplateTy &Result) {
2919  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
2920    Diag(TemplateKWLoc,
2921         getLangOpts().CPlusPlus11 ?
2922           diag::warn_cxx98_compat_template_outside_of_template :
2923           diag::ext_template_outside_of_template)
2924      << FixItHint::CreateRemoval(TemplateKWLoc);
2925
2926  DeclContext *LookupCtx = nullptr;
2927  if (SS.isSet())
2928    LookupCtx = computeDeclContext(SS, EnteringContext);
2929  if (!LookupCtx && ObjectType)
2930    LookupCtx = computeDeclContext(ObjectType.get());
2931  if (LookupCtx) {
2932    // C++0x [temp.names]p5:
2933    //   If a name prefixed by the keyword template is not the name of
2934    //   a template, the program is ill-formed. [Note: the keyword
2935    //   template may not be applied to non-template members of class
2936    //   templates. -end note ] [ Note: as is the case with the
2937    //   typename prefix, the template prefix is allowed in cases
2938    //   where it is not strictly necessary; i.e., when the
2939    //   nested-name-specifier or the expression on the left of the ->
2940    //   or . is not dependent on a template-parameter, or the use
2941    //   does not appear in the scope of a template. -end note]
2942    //
2943    // Note: C++03 was more strict here, because it banned the use of
2944    // the "template" keyword prior to a template-name that was not a
2945    // dependent name. C++ DR468 relaxed this requirement (the
2946    // "template" keyword is now permitted). We follow the C++0x
2947    // rules, even in C++03 mode with a warning, retroactively applying the DR.
2948    bool MemberOfUnknownSpecialization;
2949    TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
2950                                          ObjectType, EnteringContext, Result,
2951                                          MemberOfUnknownSpecialization);
2952    if (TNK == TNK_Non_template && LookupCtx->isDependentContext() &&
2953        isa<CXXRecordDecl>(LookupCtx) &&
2954        (!cast<CXXRecordDecl>(LookupCtx)->hasDefinition() ||
2955         cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases())) {
2956      // This is a dependent template. Handle it below.
2957    } else if (TNK == TNK_Non_template) {
2958      Diag(Name.getLocStart(),
2959           diag::err_template_kw_refers_to_non_template)
2960        << GetNameFromUnqualifiedId(Name).getName()
2961        << Name.getSourceRange()
2962        << TemplateKWLoc;
2963      return TNK_Non_template;
2964    } else {
2965      // We found something; return it.
2966      return TNK;
2967    }
2968  }
2969
2970  NestedNameSpecifier *Qualifier = SS.getScopeRep();
2971
2972  switch (Name.getKind()) {
2973  case UnqualifiedId::IK_Identifier:
2974    Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
2975                                                              Name.Identifier));
2976    return TNK_Dependent_template_name;
2977
2978  case UnqualifiedId::IK_OperatorFunctionId:
2979    Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
2980                                             Name.OperatorFunctionId.Operator));
2981    return TNK_Function_template;
2982
2983  case UnqualifiedId::IK_LiteralOperatorId:
2984    llvm_unreachable("literal operator id cannot have a dependent scope");
2985
2986  default:
2987    break;
2988  }
2989
2990  Diag(Name.getLocStart(),
2991       diag::err_template_kw_refers_to_non_template)
2992    << GetNameFromUnqualifiedId(Name).getName()
2993    << Name.getSourceRange()
2994    << TemplateKWLoc;
2995  return TNK_Non_template;
2996}
2997
2998bool Sema::CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
2999                                     TemplateArgumentLoc &AL,
3000                          SmallVectorImpl<TemplateArgument> &Converted) {
3001  const TemplateArgument &Arg = AL.getArgument();
3002  QualType ArgType;
3003  TypeSourceInfo *TSI = nullptr;
3004
3005  // Check template type parameter.
3006  switch(Arg.getKind()) {
3007  case TemplateArgument::Type:
3008    // C++ [temp.arg.type]p1:
3009    //   A template-argument for a template-parameter which is a
3010    //   type shall be a type-id.
3011    ArgType = Arg.getAsType();
3012    TSI = AL.getTypeSourceInfo();
3013    break;
3014  case TemplateArgument::Template: {
3015    // We have a template type parameter but the template argument
3016    // is a template without any arguments.
3017    SourceRange SR = AL.getSourceRange();
3018    TemplateName Name = Arg.getAsTemplate();
3019    Diag(SR.getBegin(), diag::err_template_missing_args)
3020      << Name << SR;
3021    if (TemplateDecl *Decl = Name.getAsTemplateDecl())
3022      Diag(Decl->getLocation(), diag::note_template_decl_here);
3023
3024    return true;
3025  }
3026  case TemplateArgument::Expression: {
3027    // We have a template type parameter but the template argument is an
3028    // expression; see if maybe it is missing the "typename" keyword.
3029    CXXScopeSpec SS;
3030    DeclarationNameInfo NameInfo;
3031
3032    if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
3033      SS.Adopt(ArgExpr->getQualifierLoc());
3034      NameInfo = ArgExpr->getNameInfo();
3035    } else if (DependentScopeDeclRefExpr *ArgExpr =
3036               dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
3037      SS.Adopt(ArgExpr->getQualifierLoc());
3038      NameInfo = ArgExpr->getNameInfo();
3039    } else if (CXXDependentScopeMemberExpr *ArgExpr =
3040               dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
3041      if (ArgExpr->isImplicitAccess()) {
3042        SS.Adopt(ArgExpr->getQualifierLoc());
3043        NameInfo = ArgExpr->getMemberNameInfo();
3044      }
3045    }
3046
3047    if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
3048      LookupResult Result(*this, NameInfo, LookupOrdinaryName);
3049      LookupParsedName(Result, CurScope, &SS);
3050
3051      if (Result.getAsSingle<TypeDecl>() ||
3052          Result.getResultKind() ==
3053              LookupResult::NotFoundInCurrentInstantiation) {
3054        // Suggest that the user add 'typename' before the NNS.
3055        SourceLocation Loc = AL.getSourceRange().getBegin();
3056        Diag(Loc, getLangOpts().MSVCCompat
3057                      ? diag::ext_ms_template_type_arg_missing_typename
3058                      : diag::err_template_arg_must_be_type_suggest)
3059            << FixItHint::CreateInsertion(Loc, "typename ");
3060        Diag(Param->getLocation(), diag::note_template_param_here);
3061
3062        // Recover by synthesizing a type using the location information that we
3063        // already have.
3064        ArgType =
3065            Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
3066        TypeLocBuilder TLB;
3067        DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
3068        TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
3069        TL.setQualifierLoc(SS.getWithLocInContext(Context));
3070        TL.setNameLoc(NameInfo.getLoc());
3071        TSI = TLB.getTypeSourceInfo(Context, ArgType);
3072
3073        // Overwrite our input TemplateArgumentLoc so that we can recover
3074        // properly.
3075        AL = TemplateArgumentLoc(TemplateArgument(ArgType),
3076                                 TemplateArgumentLocInfo(TSI));
3077
3078        break;
3079      }
3080    }
3081    // fallthrough
3082  }
3083  default: {
3084    // We have a template type parameter but the template argument
3085    // is not a type.
3086    SourceRange SR = AL.getSourceRange();
3087    Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
3088    Diag(Param->getLocation(), diag::note_template_param_here);
3089
3090    return true;
3091  }
3092  }
3093
3094  if (CheckTemplateArgument(Param, TSI))
3095    return true;
3096
3097  // Add the converted template type argument.
3098  ArgType = Context.getCanonicalType(ArgType);
3099
3100  // Objective-C ARC:
3101  //   If an explicitly-specified template argument type is a lifetime type
3102  //   with no lifetime qualifier, the __strong lifetime qualifier is inferred.
3103  if (getLangOpts().ObjCAutoRefCount &&
3104      ArgType->isObjCLifetimeType() &&
3105      !ArgType.getObjCLifetime()) {
3106    Qualifiers Qs;
3107    Qs.setObjCLifetime(Qualifiers::OCL_Strong);
3108    ArgType = Context.getQualifiedType(ArgType, Qs);
3109  }
3110
3111  Converted.push_back(TemplateArgument(ArgType));
3112  return false;
3113}
3114
3115/// \brief Substitute template arguments into the default template argument for
3116/// the given template type parameter.
3117///
3118/// \param SemaRef the semantic analysis object for which we are performing
3119/// the substitution.
3120///
3121/// \param Template the template that we are synthesizing template arguments
3122/// for.
3123///
3124/// \param TemplateLoc the location of the template name that started the
3125/// template-id we are checking.
3126///
3127/// \param RAngleLoc the location of the right angle bracket ('>') that
3128/// terminates the template-id.
3129///
3130/// \param Param the template template parameter whose default we are
3131/// substituting into.
3132///
3133/// \param Converted the list of template arguments provided for template
3134/// parameters that precede \p Param in the template parameter list.
3135/// \returns the substituted template argument, or NULL if an error occurred.
3136static TypeSourceInfo *
3137SubstDefaultTemplateArgument(Sema &SemaRef,
3138                             TemplateDecl *Template,
3139                             SourceLocation TemplateLoc,
3140                             SourceLocation RAngleLoc,
3141                             TemplateTypeParmDecl *Param,
3142                         SmallVectorImpl<TemplateArgument> &Converted) {
3143  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
3144
3145  // If the argument type is dependent, instantiate it now based
3146  // on the previously-computed template arguments.
3147  if (ArgType->getType()->isDependentType()) {
3148    Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
3149                                     Template, Converted,
3150                                     SourceRange(TemplateLoc, RAngleLoc));
3151    if (Inst.isInvalid())
3152      return nullptr;
3153
3154    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3155                                      Converted.data(), Converted.size());
3156
3157    // Only substitute for the innermost template argument list.
3158    MultiLevelTemplateArgumentList TemplateArgLists;
3159    TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3160    for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3161      TemplateArgLists.addOuterTemplateArguments(None);
3162
3163    Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
3164    ArgType =
3165        SemaRef.SubstType(ArgType, TemplateArgLists,
3166                          Param->getDefaultArgumentLoc(), Param->getDeclName());
3167  }
3168
3169  return ArgType;
3170}
3171
3172/// \brief Substitute template arguments into the default template argument for
3173/// the given non-type template parameter.
3174///
3175/// \param SemaRef the semantic analysis object for which we are performing
3176/// the substitution.
3177///
3178/// \param Template the template that we are synthesizing template arguments
3179/// for.
3180///
3181/// \param TemplateLoc the location of the template name that started the
3182/// template-id we are checking.
3183///
3184/// \param RAngleLoc the location of the right angle bracket ('>') that
3185/// terminates the template-id.
3186///
3187/// \param Param the non-type template parameter whose default we are
3188/// substituting into.
3189///
3190/// \param Converted the list of template arguments provided for template
3191/// parameters that precede \p Param in the template parameter list.
3192///
3193/// \returns the substituted template argument, or NULL if an error occurred.
3194static ExprResult
3195SubstDefaultTemplateArgument(Sema &SemaRef,
3196                             TemplateDecl *Template,
3197                             SourceLocation TemplateLoc,
3198                             SourceLocation RAngleLoc,
3199                             NonTypeTemplateParmDecl *Param,
3200                        SmallVectorImpl<TemplateArgument> &Converted) {
3201  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
3202                                   Template, Converted,
3203                                   SourceRange(TemplateLoc, RAngleLoc));
3204  if (Inst.isInvalid())
3205    return ExprError();
3206
3207  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3208                                    Converted.data(), Converted.size());
3209
3210  // Only substitute for the innermost template argument list.
3211  MultiLevelTemplateArgumentList TemplateArgLists;
3212  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3213  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3214    TemplateArgLists.addOuterTemplateArguments(None);
3215
3216  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
3217  EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
3218  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
3219}
3220
3221/// \brief Substitute template arguments into the default template argument for
3222/// the given template template parameter.
3223///
3224/// \param SemaRef the semantic analysis object for which we are performing
3225/// the substitution.
3226///
3227/// \param Template the template that we are synthesizing template arguments
3228/// for.
3229///
3230/// \param TemplateLoc the location of the template name that started the
3231/// template-id we are checking.
3232///
3233/// \param RAngleLoc the location of the right angle bracket ('>') that
3234/// terminates the template-id.
3235///
3236/// \param Param the template template parameter whose default we are
3237/// substituting into.
3238///
3239/// \param Converted the list of template arguments provided for template
3240/// parameters that precede \p Param in the template parameter list.
3241///
3242/// \param QualifierLoc Will be set to the nested-name-specifier (with
3243/// source-location information) that precedes the template name.
3244///
3245/// \returns the substituted template argument, or NULL if an error occurred.
3246static TemplateName
3247SubstDefaultTemplateArgument(Sema &SemaRef,
3248                             TemplateDecl *Template,
3249                             SourceLocation TemplateLoc,
3250                             SourceLocation RAngleLoc,
3251                             TemplateTemplateParmDecl *Param,
3252                       SmallVectorImpl<TemplateArgument> &Converted,
3253                             NestedNameSpecifierLoc &QualifierLoc) {
3254  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc, Template, Converted,
3255                                   SourceRange(TemplateLoc, RAngleLoc));
3256  if (Inst.isInvalid())
3257    return TemplateName();
3258
3259  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3260                                    Converted.data(), Converted.size());
3261
3262  // Only substitute for the innermost template argument list.
3263  MultiLevelTemplateArgumentList TemplateArgLists;
3264  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3265  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3266    TemplateArgLists.addOuterTemplateArguments(None);
3267
3268  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
3269  // Substitute into the nested-name-specifier first,
3270  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
3271  if (QualifierLoc) {
3272    QualifierLoc =
3273        SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
3274    if (!QualifierLoc)
3275      return TemplateName();
3276  }
3277
3278  return SemaRef.SubstTemplateName(
3279             QualifierLoc,
3280             Param->getDefaultArgument().getArgument().getAsTemplate(),
3281             Param->getDefaultArgument().getTemplateNameLoc(),
3282             TemplateArgLists);
3283}
3284
3285/// \brief If the given template parameter has a default template
3286/// argument, substitute into that default template argument and
3287/// return the corresponding template argument.
3288TemplateArgumentLoc
3289Sema::SubstDefaultTemplateArgumentIfAvailable(TemplateDecl *Template,
3290                                              SourceLocation TemplateLoc,
3291                                              SourceLocation RAngleLoc,
3292                                              Decl *Param,
3293                                              SmallVectorImpl<TemplateArgument>
3294                                                &Converted,
3295                                              bool &HasDefaultArg) {
3296  HasDefaultArg = false;
3297
3298  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
3299    if (!TypeParm->hasDefaultArgument())
3300      return TemplateArgumentLoc();
3301
3302    HasDefaultArg = true;
3303    TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
3304                                                      TemplateLoc,
3305                                                      RAngleLoc,
3306                                                      TypeParm,
3307                                                      Converted);
3308    if (DI)
3309      return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
3310
3311    return TemplateArgumentLoc();
3312  }
3313
3314  if (NonTypeTemplateParmDecl *NonTypeParm
3315        = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3316    if (!NonTypeParm->hasDefaultArgument())
3317      return TemplateArgumentLoc();
3318
3319    HasDefaultArg = true;
3320    ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
3321                                                  TemplateLoc,
3322                                                  RAngleLoc,
3323                                                  NonTypeParm,
3324                                                  Converted);
3325    if (Arg.isInvalid())
3326      return TemplateArgumentLoc();
3327
3328    Expr *ArgE = Arg.getAs<Expr>();
3329    return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
3330  }
3331
3332  TemplateTemplateParmDecl *TempTempParm
3333    = cast<TemplateTemplateParmDecl>(Param);
3334  if (!TempTempParm->hasDefaultArgument())
3335    return TemplateArgumentLoc();
3336
3337  HasDefaultArg = true;
3338  NestedNameSpecifierLoc QualifierLoc;
3339  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
3340                                                    TemplateLoc,
3341                                                    RAngleLoc,
3342                                                    TempTempParm,
3343                                                    Converted,
3344                                                    QualifierLoc);
3345  if (TName.isNull())
3346    return TemplateArgumentLoc();
3347
3348  return TemplateArgumentLoc(TemplateArgument(TName),
3349                TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
3350                TempTempParm->getDefaultArgument().getTemplateNameLoc());
3351}
3352
3353/// \brief Check that the given template argument corresponds to the given
3354/// template parameter.
3355///
3356/// \param Param The template parameter against which the argument will be
3357/// checked.
3358///
3359/// \param Arg The template argument.
3360///
3361/// \param Template The template in which the template argument resides.
3362///
3363/// \param TemplateLoc The location of the template name for the template
3364/// whose argument list we're matching.
3365///
3366/// \param RAngleLoc The location of the right angle bracket ('>') that closes
3367/// the template argument list.
3368///
3369/// \param ArgumentPackIndex The index into the argument pack where this
3370/// argument will be placed. Only valid if the parameter is a parameter pack.
3371///
3372/// \param Converted The checked, converted argument will be added to the
3373/// end of this small vector.
3374///
3375/// \param CTAK Describes how we arrived at this particular template argument:
3376/// explicitly written, deduced, etc.
3377///
3378/// \returns true on error, false otherwise.
3379bool Sema::CheckTemplateArgument(NamedDecl *Param,
3380                                 TemplateArgumentLoc &Arg,
3381                                 NamedDecl *Template,
3382                                 SourceLocation TemplateLoc,
3383                                 SourceLocation RAngleLoc,
3384                                 unsigned ArgumentPackIndex,
3385                            SmallVectorImpl<TemplateArgument> &Converted,
3386                                 CheckTemplateArgumentKind CTAK) {
3387  // Check template type parameters.
3388  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
3389    return CheckTemplateTypeArgument(TTP, Arg, Converted);
3390
3391  // Check non-type template parameters.
3392  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3393    // Do substitution on the type of the non-type template parameter
3394    // with the template arguments we've seen thus far.  But if the
3395    // template has a dependent context then we cannot substitute yet.
3396    QualType NTTPType = NTTP->getType();
3397    if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
3398      NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
3399
3400    if (NTTPType->isDependentType() &&
3401        !isa<TemplateTemplateParmDecl>(Template) &&
3402        !Template->getDeclContext()->isDependentContext()) {
3403      // Do substitution on the type of the non-type template parameter.
3404      InstantiatingTemplate Inst(*this, TemplateLoc, Template,
3405                                 NTTP, Converted,
3406                                 SourceRange(TemplateLoc, RAngleLoc));
3407      if (Inst.isInvalid())
3408        return true;
3409
3410      TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3411                                        Converted.data(), Converted.size());
3412      NTTPType = SubstType(NTTPType,
3413                           MultiLevelTemplateArgumentList(TemplateArgs),
3414                           NTTP->getLocation(),
3415                           NTTP->getDeclName());
3416      // If that worked, check the non-type template parameter type
3417      // for validity.
3418      if (!NTTPType.isNull())
3419        NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
3420                                                     NTTP->getLocation());
3421      if (NTTPType.isNull())
3422        return true;
3423    }
3424
3425    switch (Arg.getArgument().getKind()) {
3426    case TemplateArgument::Null:
3427      llvm_unreachable("Should never see a NULL template argument here");
3428
3429    case TemplateArgument::Expression: {
3430      TemplateArgument Result;
3431      ExprResult Res =
3432        CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
3433                              Result, CTAK);
3434      if (Res.isInvalid())
3435        return true;
3436
3437      Converted.push_back(Result);
3438      break;
3439    }
3440
3441    case TemplateArgument::Declaration:
3442    case TemplateArgument::Integral:
3443    case TemplateArgument::NullPtr:
3444      // We've already checked this template argument, so just copy
3445      // it to the list of converted arguments.
3446      Converted.push_back(Arg.getArgument());
3447      break;
3448
3449    case TemplateArgument::Template:
3450    case TemplateArgument::TemplateExpansion:
3451      // We were given a template template argument. It may not be ill-formed;
3452      // see below.
3453      if (DependentTemplateName *DTN
3454            = Arg.getArgument().getAsTemplateOrTemplatePattern()
3455                                              .getAsDependentTemplateName()) {
3456        // We have a template argument such as \c T::template X, which we
3457        // parsed as a template template argument. However, since we now
3458        // know that we need a non-type template argument, convert this
3459        // template name into an expression.
3460
3461        DeclarationNameInfo NameInfo(DTN->getIdentifier(),
3462                                     Arg.getTemplateNameLoc());
3463
3464        CXXScopeSpec SS;
3465        SS.Adopt(Arg.getTemplateQualifierLoc());
3466        // FIXME: the template-template arg was a DependentTemplateName,
3467        // so it was provided with a template keyword. However, its source
3468        // location is not stored in the template argument structure.
3469        SourceLocation TemplateKWLoc;
3470        ExprResult E = DependentScopeDeclRefExpr::Create(
3471            Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
3472            nullptr);
3473
3474        // If we parsed the template argument as a pack expansion, create a
3475        // pack expansion expression.
3476        if (Arg.getArgument().getKind() == TemplateArgument::TemplateExpansion){
3477          E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
3478          if (E.isInvalid())
3479            return true;
3480        }
3481
3482        TemplateArgument Result;
3483        E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
3484        if (E.isInvalid())
3485          return true;
3486
3487        Converted.push_back(Result);
3488        break;
3489      }
3490
3491      // We have a template argument that actually does refer to a class
3492      // template, alias template, or template template parameter, and
3493      // therefore cannot be a non-type template argument.
3494      Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
3495        << Arg.getSourceRange();
3496
3497      Diag(Param->getLocation(), diag::note_template_param_here);
3498      return true;
3499
3500    case TemplateArgument::Type: {
3501      // We have a non-type template parameter but the template
3502      // argument is a type.
3503
3504      // C++ [temp.arg]p2:
3505      //   In a template-argument, an ambiguity between a type-id and
3506      //   an expression is resolved to a type-id, regardless of the
3507      //   form of the corresponding template-parameter.
3508      //
3509      // We warn specifically about this case, since it can be rather
3510      // confusing for users.
3511      QualType T = Arg.getArgument().getAsType();
3512      SourceRange SR = Arg.getSourceRange();
3513      if (T->isFunctionType())
3514        Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
3515      else
3516        Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
3517      Diag(Param->getLocation(), diag::note_template_param_here);
3518      return true;
3519    }
3520
3521    case TemplateArgument::Pack:
3522      llvm_unreachable("Caller must expand template argument packs");
3523    }
3524
3525    return false;
3526  }
3527
3528
3529  // Check template template parameters.
3530  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
3531
3532  // Substitute into the template parameter list of the template
3533  // template parameter, since previously-supplied template arguments
3534  // may appear within the template template parameter.
3535  {
3536    // Set up a template instantiation context.
3537    LocalInstantiationScope Scope(*this);
3538    InstantiatingTemplate Inst(*this, TemplateLoc, Template,
3539                               TempParm, Converted,
3540                               SourceRange(TemplateLoc, RAngleLoc));
3541    if (Inst.isInvalid())
3542      return true;
3543
3544    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3545                                      Converted.data(), Converted.size());
3546    TempParm = cast_or_null<TemplateTemplateParmDecl>(
3547                      SubstDecl(TempParm, CurContext,
3548                                MultiLevelTemplateArgumentList(TemplateArgs)));
3549    if (!TempParm)
3550      return true;
3551  }
3552
3553  switch (Arg.getArgument().getKind()) {
3554  case TemplateArgument::Null:
3555    llvm_unreachable("Should never see a NULL template argument here");
3556
3557  case TemplateArgument::Template:
3558  case TemplateArgument::TemplateExpansion:
3559    if (CheckTemplateArgument(TempParm, Arg, ArgumentPackIndex))
3560      return true;
3561
3562    Converted.push_back(Arg.getArgument());
3563    break;
3564
3565  case TemplateArgument::Expression:
3566  case TemplateArgument::Type:
3567    // We have a template template parameter but the template
3568    // argument does not refer to a template.
3569    Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
3570      << getLangOpts().CPlusPlus11;
3571    return true;
3572
3573  case TemplateArgument::Declaration:
3574    llvm_unreachable("Declaration argument with template template parameter");
3575  case TemplateArgument::Integral:
3576    llvm_unreachable("Integral argument with template template parameter");
3577  case TemplateArgument::NullPtr:
3578    llvm_unreachable("Null pointer argument with template template parameter");
3579
3580  case TemplateArgument::Pack:
3581    llvm_unreachable("Caller must expand template argument packs");
3582  }
3583
3584  return false;
3585}
3586
3587/// \brief Diagnose an arity mismatch in the
3588static bool diagnoseArityMismatch(Sema &S, TemplateDecl *Template,
3589                                  SourceLocation TemplateLoc,
3590                                  TemplateArgumentListInfo &TemplateArgs) {
3591  TemplateParameterList *Params = Template->getTemplateParameters();
3592  unsigned NumParams = Params->size();
3593  unsigned NumArgs = TemplateArgs.size();
3594
3595  SourceRange Range;
3596  if (NumArgs > NumParams)
3597    Range = SourceRange(TemplateArgs[NumParams].getLocation(),
3598                        TemplateArgs.getRAngleLoc());
3599  S.Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
3600    << (NumArgs > NumParams)
3601    << (isa<ClassTemplateDecl>(Template)? 0 :
3602        isa<FunctionTemplateDecl>(Template)? 1 :
3603        isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
3604    << Template << Range;
3605  S.Diag(Template->getLocation(), diag::note_template_decl_here)
3606    << Params->getSourceRange();
3607  return true;
3608}
3609
3610/// \brief Check whether the template parameter is a pack expansion, and if so,
3611/// determine the number of parameters produced by that expansion. For instance:
3612///
3613/// \code
3614/// template<typename ...Ts> struct A {
3615///   template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
3616/// };
3617/// \endcode
3618///
3619/// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
3620/// is not a pack expansion, so returns an empty Optional.
3621static Optional<unsigned> getExpandedPackSize(NamedDecl *Param) {
3622  if (NonTypeTemplateParmDecl *NTTP
3623        = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3624    if (NTTP->isExpandedParameterPack())
3625      return NTTP->getNumExpansionTypes();
3626  }
3627
3628  if (TemplateTemplateParmDecl *TTP
3629        = dyn_cast<TemplateTemplateParmDecl>(Param)) {
3630    if (TTP->isExpandedParameterPack())
3631      return TTP->getNumExpansionTemplateParameters();
3632  }
3633
3634  return None;
3635}
3636
3637/// \brief Check that the given template argument list is well-formed
3638/// for specializing the given template.
3639bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
3640                                     SourceLocation TemplateLoc,
3641                                     TemplateArgumentListInfo &TemplateArgs,
3642                                     bool PartialTemplateArgs,
3643                          SmallVectorImpl<TemplateArgument> &Converted) {
3644  TemplateParameterList *Params = Template->getTemplateParameters();
3645
3646  SourceLocation RAngleLoc = TemplateArgs.getRAngleLoc();
3647
3648  // C++ [temp.arg]p1:
3649  //   [...] The type and form of each template-argument specified in
3650  //   a template-id shall match the type and form specified for the
3651  //   corresponding parameter declared by the template in its
3652  //   template-parameter-list.
3653  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
3654  SmallVector<TemplateArgument, 2> ArgumentPack;
3655  unsigned ArgIdx = 0, NumArgs = TemplateArgs.size();
3656  LocalInstantiationScope InstScope(*this, true);
3657  for (TemplateParameterList::iterator Param = Params->begin(),
3658                                       ParamEnd = Params->end();
3659       Param != ParamEnd; /* increment in loop */) {
3660    // If we have an expanded parameter pack, make sure we don't have too
3661    // many arguments.
3662    if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
3663      if (*Expansions == ArgumentPack.size()) {
3664        // We're done with this parameter pack. Pack up its arguments and add
3665        // them to the list.
3666        Converted.push_back(
3667          TemplateArgument::CreatePackCopy(Context,
3668                                           ArgumentPack.data(),
3669                                           ArgumentPack.size()));
3670        ArgumentPack.clear();
3671
3672        // This argument is assigned to the next parameter.
3673        ++Param;
3674        continue;
3675      } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
3676        // Not enough arguments for this parameter pack.
3677        Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
3678          << false
3679          << (isa<ClassTemplateDecl>(Template)? 0 :
3680              isa<FunctionTemplateDecl>(Template)? 1 :
3681              isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
3682          << Template;
3683        Diag(Template->getLocation(), diag::note_template_decl_here)
3684          << Params->getSourceRange();
3685        return true;
3686      }
3687    }
3688
3689    if (ArgIdx < NumArgs) {
3690      // Check the template argument we were given.
3691      if (CheckTemplateArgument(*Param, TemplateArgs[ArgIdx], Template,
3692                                TemplateLoc, RAngleLoc,
3693                                ArgumentPack.size(), Converted))
3694        return true;
3695
3696      if (TemplateArgs[ArgIdx].getArgument().isPackExpansion() &&
3697          isa<TypeAliasTemplateDecl>(Template) &&
3698          !(Param + 1 == ParamEnd && (*Param)->isTemplateParameterPack() &&
3699            !getExpandedPackSize(*Param))) {
3700        // Core issue 1430: we have a pack expansion as an argument to an
3701        // alias template, and it's not part of a final parameter pack. This
3702        // can't be canonicalized, so reject it now.
3703        Diag(TemplateArgs[ArgIdx].getLocation(),
3704             diag::err_alias_template_expansion_into_fixed_list)
3705          << TemplateArgs[ArgIdx].getSourceRange();
3706        Diag((*Param)->getLocation(), diag::note_template_param_here);
3707        return true;
3708      }
3709
3710      // We're now done with this argument.
3711      ++ArgIdx;
3712
3713      if ((*Param)->isTemplateParameterPack()) {
3714        // The template parameter was a template parameter pack, so take the
3715        // deduced argument and place it on the argument pack. Note that we
3716        // stay on the same template parameter so that we can deduce more
3717        // arguments.
3718        ArgumentPack.push_back(Converted.pop_back_val());
3719      } else {
3720        // Move to the next template parameter.
3721        ++Param;
3722      }
3723
3724      // If we just saw a pack expansion, then directly convert the remaining
3725      // arguments, because we don't know what parameters they'll match up
3726      // with.
3727      if (TemplateArgs[ArgIdx-1].getArgument().isPackExpansion()) {
3728        bool InFinalParameterPack = Param != ParamEnd &&
3729                                    Param + 1 == ParamEnd &&
3730                                    (*Param)->isTemplateParameterPack() &&
3731                                    !getExpandedPackSize(*Param);
3732
3733        if (!InFinalParameterPack && !ArgumentPack.empty()) {
3734          // If we were part way through filling in an expanded parameter pack,
3735          // fall back to just producing individual arguments.
3736          Converted.insert(Converted.end(),
3737                           ArgumentPack.begin(), ArgumentPack.end());
3738          ArgumentPack.clear();
3739        }
3740
3741        while (ArgIdx < NumArgs) {
3742          if (InFinalParameterPack)
3743            ArgumentPack.push_back(TemplateArgs[ArgIdx].getArgument());
3744          else
3745            Converted.push_back(TemplateArgs[ArgIdx].getArgument());
3746          ++ArgIdx;
3747        }
3748
3749        // Push the argument pack onto the list of converted arguments.
3750        if (InFinalParameterPack) {
3751          Converted.push_back(
3752            TemplateArgument::CreatePackCopy(Context,
3753                                             ArgumentPack.data(),
3754                                             ArgumentPack.size()));
3755          ArgumentPack.clear();
3756        }
3757
3758        return false;
3759      }
3760
3761      continue;
3762    }
3763
3764    // If we're checking a partial template argument list, we're done.
3765    if (PartialTemplateArgs) {
3766      if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
3767        Converted.push_back(TemplateArgument::CreatePackCopy(Context,
3768                                                         ArgumentPack.data(),
3769                                                         ArgumentPack.size()));
3770
3771      return false;
3772    }
3773
3774    // If we have a template parameter pack with no more corresponding
3775    // arguments, just break out now and we'll fill in the argument pack below.
3776    if ((*Param)->isTemplateParameterPack()) {
3777      assert(!getExpandedPackSize(*Param) &&
3778             "Should have dealt with this already");
3779
3780      // A non-expanded parameter pack before the end of the parameter list
3781      // only occurs for an ill-formed template parameter list, unless we've
3782      // got a partial argument list for a function template, so just bail out.
3783      if (Param + 1 != ParamEnd)
3784        return true;
3785
3786      Converted.push_back(TemplateArgument::CreatePackCopy(Context,
3787                                                       ArgumentPack.data(),
3788                                                       ArgumentPack.size()));
3789      ArgumentPack.clear();
3790
3791      ++Param;
3792      continue;
3793    }
3794
3795    // Check whether we have a default argument.
3796    TemplateArgumentLoc Arg;
3797
3798    // Retrieve the default template argument from the template
3799    // parameter. For each kind of template parameter, we substitute the
3800    // template arguments provided thus far and any "outer" template arguments
3801    // (when the template parameter was part of a nested template) into
3802    // the default argument.
3803    if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
3804      if (!TTP->hasDefaultArgument())
3805        return diagnoseArityMismatch(*this, Template, TemplateLoc,
3806                                     TemplateArgs);
3807
3808      TypeSourceInfo *ArgType = SubstDefaultTemplateArgument(*this,
3809                                                             Template,
3810                                                             TemplateLoc,
3811                                                             RAngleLoc,
3812                                                             TTP,
3813                                                             Converted);
3814      if (!ArgType)
3815        return true;
3816
3817      Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
3818                                ArgType);
3819    } else if (NonTypeTemplateParmDecl *NTTP
3820                 = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
3821      if (!NTTP->hasDefaultArgument())
3822        return diagnoseArityMismatch(*this, Template, TemplateLoc,
3823                                     TemplateArgs);
3824
3825      ExprResult E = SubstDefaultTemplateArgument(*this, Template,
3826                                                              TemplateLoc,
3827                                                              RAngleLoc,
3828                                                              NTTP,
3829                                                              Converted);
3830      if (E.isInvalid())
3831        return true;
3832
3833      Expr *Ex = E.getAs<Expr>();
3834      Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
3835    } else {
3836      TemplateTemplateParmDecl *TempParm
3837        = cast<TemplateTemplateParmDecl>(*Param);
3838
3839      if (!TempParm->hasDefaultArgument())
3840        return diagnoseArityMismatch(*this, Template, TemplateLoc,
3841                                     TemplateArgs);
3842
3843      NestedNameSpecifierLoc QualifierLoc;
3844      TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
3845                                                       TemplateLoc,
3846                                                       RAngleLoc,
3847                                                       TempParm,
3848                                                       Converted,
3849                                                       QualifierLoc);
3850      if (Name.isNull())
3851        return true;
3852
3853      Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
3854                           TempParm->getDefaultArgument().getTemplateNameLoc());
3855    }
3856
3857    // Introduce an instantiation record that describes where we are using
3858    // the default template argument.
3859    InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
3860                               SourceRange(TemplateLoc, RAngleLoc));
3861    if (Inst.isInvalid())
3862      return true;
3863
3864    // Check the default template argument.
3865    if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
3866                              RAngleLoc, 0, Converted))
3867      return true;
3868
3869    // Core issue 150 (assumed resolution): if this is a template template
3870    // parameter, keep track of the default template arguments from the
3871    // template definition.
3872    if (isTemplateTemplateParameter)
3873      TemplateArgs.addArgument(Arg);
3874
3875    // Move to the next template parameter and argument.
3876    ++Param;
3877    ++ArgIdx;
3878  }
3879
3880  // If we're performing a partial argument substitution, allow any trailing
3881  // pack expansions; they might be empty. This can happen even if
3882  // PartialTemplateArgs is false (the list of arguments is complete but
3883  // still dependent).
3884  if (ArgIdx < NumArgs && CurrentInstantiationScope &&
3885      CurrentInstantiationScope->getPartiallySubstitutedPack()) {
3886    while (ArgIdx < NumArgs &&
3887           TemplateArgs[ArgIdx].getArgument().isPackExpansion())
3888      Converted.push_back(TemplateArgs[ArgIdx++].getArgument());
3889  }
3890
3891  // If we have any leftover arguments, then there were too many arguments.
3892  // Complain and fail.
3893  if (ArgIdx < NumArgs)
3894    return diagnoseArityMismatch(*this, Template, TemplateLoc, TemplateArgs);
3895
3896  return false;
3897}
3898
3899namespace {
3900  class UnnamedLocalNoLinkageFinder
3901    : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
3902  {
3903    Sema &S;
3904    SourceRange SR;
3905
3906    typedef TypeVisitor<UnnamedLocalNoLinkageFinder, bool> inherited;
3907
3908  public:
3909    UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
3910
3911    bool Visit(QualType T) {
3912      return inherited::Visit(T.getTypePtr());
3913    }
3914
3915#define TYPE(Class, Parent) \
3916    bool Visit##Class##Type(const Class##Type *);
3917#define ABSTRACT_TYPE(Class, Parent) \
3918    bool Visit##Class##Type(const Class##Type *) { return false; }
3919#define NON_CANONICAL_TYPE(Class, Parent) \
3920    bool Visit##Class##Type(const Class##Type *) { return false; }
3921#include "clang/AST/TypeNodes.def"
3922
3923    bool VisitTagDecl(const TagDecl *Tag);
3924    bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
3925  };
3926}
3927
3928bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
3929  return false;
3930}
3931
3932bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
3933  return Visit(T->getElementType());
3934}
3935
3936bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
3937  return Visit(T->getPointeeType());
3938}
3939
3940bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
3941                                                    const BlockPointerType* T) {
3942  return Visit(T->getPointeeType());
3943}
3944
3945bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
3946                                                const LValueReferenceType* T) {
3947  return Visit(T->getPointeeType());
3948}
3949
3950bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
3951                                                const RValueReferenceType* T) {
3952  return Visit(T->getPointeeType());
3953}
3954
3955bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
3956                                                  const MemberPointerType* T) {
3957  return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
3958}
3959
3960bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
3961                                                  const ConstantArrayType* T) {
3962  return Visit(T->getElementType());
3963}
3964
3965bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
3966                                                 const IncompleteArrayType* T) {
3967  return Visit(T->getElementType());
3968}
3969
3970bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
3971                                                   const VariableArrayType* T) {
3972  return Visit(T->getElementType());
3973}
3974
3975bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
3976                                            const DependentSizedArrayType* T) {
3977  return Visit(T->getElementType());
3978}
3979
3980bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
3981                                         const DependentSizedExtVectorType* T) {
3982  return Visit(T->getElementType());
3983}
3984
3985bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
3986  return Visit(T->getElementType());
3987}
3988
3989bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
3990  return Visit(T->getElementType());
3991}
3992
3993bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
3994                                                  const FunctionProtoType* T) {
3995  for (const auto &A : T->param_types()) {
3996    if (Visit(A))
3997      return true;
3998  }
3999
4000  return Visit(T->getReturnType());
4001}
4002
4003bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
4004                                               const FunctionNoProtoType* T) {
4005  return Visit(T->getReturnType());
4006}
4007
4008bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
4009                                                  const UnresolvedUsingType*) {
4010  return false;
4011}
4012
4013bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
4014  return false;
4015}
4016
4017bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
4018  return Visit(T->getUnderlyingType());
4019}
4020
4021bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
4022  return false;
4023}
4024
4025bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
4026                                                    const UnaryTransformType*) {
4027  return false;
4028}
4029
4030bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
4031  return Visit(T->getDeducedType());
4032}
4033
4034bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
4035  return VisitTagDecl(T->getDecl());
4036}
4037
4038bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
4039  return VisitTagDecl(T->getDecl());
4040}
4041
4042bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
4043                                                 const TemplateTypeParmType*) {
4044  return false;
4045}
4046
4047bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
4048                                        const SubstTemplateTypeParmPackType *) {
4049  return false;
4050}
4051
4052bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
4053                                            const TemplateSpecializationType*) {
4054  return false;
4055}
4056
4057bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
4058                                              const InjectedClassNameType* T) {
4059  return VisitTagDecl(T->getDecl());
4060}
4061
4062bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
4063                                                   const DependentNameType* T) {
4064  return VisitNestedNameSpecifier(T->getQualifier());
4065}
4066
4067bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
4068                                 const DependentTemplateSpecializationType* T) {
4069  return VisitNestedNameSpecifier(T->getQualifier());
4070}
4071
4072bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
4073                                                   const PackExpansionType* T) {
4074  return Visit(T->getPattern());
4075}
4076
4077bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
4078  return false;
4079}
4080
4081bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
4082                                                   const ObjCInterfaceType *) {
4083  return false;
4084}
4085
4086bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
4087                                                const ObjCObjectPointerType *) {
4088  return false;
4089}
4090
4091bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
4092  return Visit(T->getValueType());
4093}
4094
4095bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
4096  if (Tag->getDeclContext()->isFunctionOrMethod()) {
4097    S.Diag(SR.getBegin(),
4098           S.getLangOpts().CPlusPlus11 ?
4099             diag::warn_cxx98_compat_template_arg_local_type :
4100             diag::ext_template_arg_local_type)
4101      << S.Context.getTypeDeclType(Tag) << SR;
4102    return true;
4103  }
4104
4105  if (!Tag->hasNameForLinkage()) {
4106    S.Diag(SR.getBegin(),
4107           S.getLangOpts().CPlusPlus11 ?
4108             diag::warn_cxx98_compat_template_arg_unnamed_type :
4109             diag::ext_template_arg_unnamed_type) << SR;
4110    S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
4111    return true;
4112  }
4113
4114  return false;
4115}
4116
4117bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
4118                                                    NestedNameSpecifier *NNS) {
4119  if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
4120    return true;
4121
4122  switch (NNS->getKind()) {
4123  case NestedNameSpecifier::Identifier:
4124  case NestedNameSpecifier::Namespace:
4125  case NestedNameSpecifier::NamespaceAlias:
4126  case NestedNameSpecifier::Global:
4127    return false;
4128
4129  case NestedNameSpecifier::TypeSpec:
4130  case NestedNameSpecifier::TypeSpecWithTemplate:
4131    return Visit(QualType(NNS->getAsType(), 0));
4132  }
4133  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
4134}
4135
4136
4137/// \brief Check a template argument against its corresponding
4138/// template type parameter.
4139///
4140/// This routine implements the semantics of C++ [temp.arg.type]. It
4141/// returns true if an error occurred, and false otherwise.
4142bool Sema::CheckTemplateArgument(TemplateTypeParmDecl *Param,
4143                                 TypeSourceInfo *ArgInfo) {
4144  assert(ArgInfo && "invalid TypeSourceInfo");
4145  QualType Arg = ArgInfo->getType();
4146  SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
4147
4148  if (Arg->isVariablyModifiedType()) {
4149    return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
4150  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
4151    return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
4152  }
4153
4154  // C++03 [temp.arg.type]p2:
4155  //   A local type, a type with no linkage, an unnamed type or a type
4156  //   compounded from any of these types shall not be used as a
4157  //   template-argument for a template type-parameter.
4158  //
4159  // C++11 allows these, and even in C++03 we allow them as an extension with
4160  // a warning.
4161  bool NeedsCheck;
4162  if (LangOpts.CPlusPlus11)
4163    NeedsCheck =
4164        !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_unnamed_type,
4165                         SR.getBegin()) ||
4166        !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_local_type,
4167                         SR.getBegin());
4168  else
4169    NeedsCheck = Arg->hasUnnamedOrLocalType();
4170
4171  if (NeedsCheck) {
4172    UnnamedLocalNoLinkageFinder Finder(*this, SR);
4173    (void)Finder.Visit(Context.getCanonicalType(Arg));
4174  }
4175
4176  return false;
4177}
4178
4179enum NullPointerValueKind {
4180  NPV_NotNullPointer,
4181  NPV_NullPointer,
4182  NPV_Error
4183};
4184
4185/// \brief Determine whether the given template argument is a null pointer
4186/// value of the appropriate type.
4187static NullPointerValueKind
4188isNullPointerValueTemplateArgument(Sema &S, NonTypeTemplateParmDecl *Param,
4189                                   QualType ParamType, Expr *Arg) {
4190  if (Arg->isValueDependent() || Arg->isTypeDependent())
4191    return NPV_NotNullPointer;
4192
4193  if (!S.getLangOpts().CPlusPlus11 || S.getLangOpts().MSVCCompat)
4194    return NPV_NotNullPointer;
4195
4196  // Determine whether we have a constant expression.
4197  ExprResult ArgRV = S.DefaultFunctionArrayConversion(Arg);
4198  if (ArgRV.isInvalid())
4199    return NPV_Error;
4200  Arg = ArgRV.get();
4201
4202  Expr::EvalResult EvalResult;
4203  SmallVector<PartialDiagnosticAt, 8> Notes;
4204  EvalResult.Diag = &Notes;
4205  if (!Arg->EvaluateAsRValue(EvalResult, S.Context) ||
4206      EvalResult.HasSideEffects) {
4207    SourceLocation DiagLoc = Arg->getExprLoc();
4208
4209    // If our only note is the usual "invalid subexpression" note, just point
4210    // the caret at its location rather than producing an essentially
4211    // redundant note.
4212    if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
4213        diag::note_invalid_subexpr_in_const_expr) {
4214      DiagLoc = Notes[0].first;
4215      Notes.clear();
4216    }
4217
4218    S.Diag(DiagLoc, diag::err_template_arg_not_address_constant)
4219      << Arg->getType() << Arg->getSourceRange();
4220    for (unsigned I = 0, N = Notes.size(); I != N; ++I)
4221      S.Diag(Notes[I].first, Notes[I].second);
4222
4223    S.Diag(Param->getLocation(), diag::note_template_param_here);
4224    return NPV_Error;
4225  }
4226
4227  // C++11 [temp.arg.nontype]p1:
4228  //   - an address constant expression of type std::nullptr_t
4229  if (Arg->getType()->isNullPtrType())
4230    return NPV_NullPointer;
4231
4232  //   - a constant expression that evaluates to a null pointer value (4.10); or
4233  //   - a constant expression that evaluates to a null member pointer value
4234  //     (4.11); or
4235  if ((EvalResult.Val.isLValue() && !EvalResult.Val.getLValueBase()) ||
4236      (EvalResult.Val.isMemberPointer() &&
4237       !EvalResult.Val.getMemberPointerDecl())) {
4238    // If our expression has an appropriate type, we've succeeded.
4239    bool ObjCLifetimeConversion;
4240    if (S.Context.hasSameUnqualifiedType(Arg->getType(), ParamType) ||
4241        S.IsQualificationConversion(Arg->getType(), ParamType, false,
4242                                     ObjCLifetimeConversion))
4243      return NPV_NullPointer;
4244
4245    // The types didn't match, but we know we got a null pointer; complain,
4246    // then recover as if the types were correct.
4247    S.Diag(Arg->getExprLoc(), diag::err_template_arg_wrongtype_null_constant)
4248      << Arg->getType() << ParamType << Arg->getSourceRange();
4249    S.Diag(Param->getLocation(), diag::note_template_param_here);
4250    return NPV_NullPointer;
4251  }
4252
4253  // If we don't have a null pointer value, but we do have a NULL pointer
4254  // constant, suggest a cast to the appropriate type.
4255  if (Arg->isNullPointerConstant(S.Context, Expr::NPC_NeverValueDependent)) {
4256    std::string Code = "static_cast<" + ParamType.getAsString() + ">(";
4257    S.Diag(Arg->getExprLoc(), diag::err_template_arg_untyped_null_constant)
4258        << ParamType << FixItHint::CreateInsertion(Arg->getLocStart(), Code)
4259        << FixItHint::CreateInsertion(S.getLocForEndOfToken(Arg->getLocEnd()),
4260                                      ")");
4261    S.Diag(Param->getLocation(), diag::note_template_param_here);
4262    return NPV_NullPointer;
4263  }
4264
4265  // FIXME: If we ever want to support general, address-constant expressions
4266  // as non-type template arguments, we should return the ExprResult here to
4267  // be interpreted by the caller.
4268  return NPV_NotNullPointer;
4269}
4270
4271/// \brief Checks whether the given template argument is compatible with its
4272/// template parameter.
4273static bool CheckTemplateArgumentIsCompatibleWithParameter(
4274    Sema &S, NonTypeTemplateParmDecl *Param, QualType ParamType, Expr *ArgIn,
4275    Expr *Arg, QualType ArgType) {
4276  bool ObjCLifetimeConversion;
4277  if (ParamType->isPointerType() &&
4278      !ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType() &&
4279      S.IsQualificationConversion(ArgType, ParamType, false,
4280                                  ObjCLifetimeConversion)) {
4281    // For pointer-to-object types, qualification conversions are
4282    // permitted.
4283  } else {
4284    if (const ReferenceType *ParamRef = ParamType->getAs<ReferenceType>()) {
4285      if (!ParamRef->getPointeeType()->isFunctionType()) {
4286        // C++ [temp.arg.nontype]p5b3:
4287        //   For a non-type template-parameter of type reference to
4288        //   object, no conversions apply. The type referred to by the
4289        //   reference may be more cv-qualified than the (otherwise
4290        //   identical) type of the template- argument. The
4291        //   template-parameter is bound directly to the
4292        //   template-argument, which shall be an lvalue.
4293
4294        // FIXME: Other qualifiers?
4295        unsigned ParamQuals = ParamRef->getPointeeType().getCVRQualifiers();
4296        unsigned ArgQuals = ArgType.getCVRQualifiers();
4297
4298        if ((ParamQuals | ArgQuals) != ParamQuals) {
4299          S.Diag(Arg->getLocStart(),
4300                 diag::err_template_arg_ref_bind_ignores_quals)
4301            << ParamType << Arg->getType() << Arg->getSourceRange();
4302          S.Diag(Param->getLocation(), diag::note_template_param_here);
4303          return true;
4304        }
4305      }
4306    }
4307
4308    // At this point, the template argument refers to an object or
4309    // function with external linkage. We now need to check whether the
4310    // argument and parameter types are compatible.
4311    if (!S.Context.hasSameUnqualifiedType(ArgType,
4312                                          ParamType.getNonReferenceType())) {
4313      // We can't perform this conversion or binding.
4314      if (ParamType->isReferenceType())
4315        S.Diag(Arg->getLocStart(), diag::err_template_arg_no_ref_bind)
4316          << ParamType << ArgIn->getType() << Arg->getSourceRange();
4317      else
4318        S.Diag(Arg->getLocStart(),  diag::err_template_arg_not_convertible)
4319          << ArgIn->getType() << ParamType << Arg->getSourceRange();
4320      S.Diag(Param->getLocation(), diag::note_template_param_here);
4321      return true;
4322    }
4323  }
4324
4325  return false;
4326}
4327
4328/// \brief Checks whether the given template argument is the address
4329/// of an object or function according to C++ [temp.arg.nontype]p1.
4330static bool
4331CheckTemplateArgumentAddressOfObjectOrFunction(Sema &S,
4332                                               NonTypeTemplateParmDecl *Param,
4333                                               QualType ParamType,
4334                                               Expr *ArgIn,
4335                                               TemplateArgument &Converted) {
4336  bool Invalid = false;
4337  Expr *Arg = ArgIn;
4338  QualType ArgType = Arg->getType();
4339
4340  bool AddressTaken = false;
4341  SourceLocation AddrOpLoc;
4342  if (S.getLangOpts().MicrosoftExt) {
4343    // Microsoft Visual C++ strips all casts, allows an arbitrary number of
4344    // dereference and address-of operators.
4345    Arg = Arg->IgnoreParenCasts();
4346
4347    bool ExtWarnMSTemplateArg = false;
4348    UnaryOperatorKind FirstOpKind;
4349    SourceLocation FirstOpLoc;
4350    while (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4351      UnaryOperatorKind UnOpKind = UnOp->getOpcode();
4352      if (UnOpKind == UO_Deref)
4353        ExtWarnMSTemplateArg = true;
4354      if (UnOpKind == UO_AddrOf || UnOpKind == UO_Deref) {
4355        Arg = UnOp->getSubExpr()->IgnoreParenCasts();
4356        if (!AddrOpLoc.isValid()) {
4357          FirstOpKind = UnOpKind;
4358          FirstOpLoc = UnOp->getOperatorLoc();
4359        }
4360      } else
4361        break;
4362    }
4363    if (FirstOpLoc.isValid()) {
4364      if (ExtWarnMSTemplateArg)
4365        S.Diag(ArgIn->getLocStart(), diag::ext_ms_deref_template_argument)
4366          << ArgIn->getSourceRange();
4367
4368      if (FirstOpKind == UO_AddrOf)
4369        AddressTaken = true;
4370      else if (Arg->getType()->isPointerType()) {
4371        // We cannot let pointers get dereferenced here, that is obviously not a
4372        // constant expression.
4373        assert(FirstOpKind == UO_Deref);
4374        S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
4375          << Arg->getSourceRange();
4376      }
4377    }
4378  } else {
4379    // See through any implicit casts we added to fix the type.
4380    Arg = Arg->IgnoreImpCasts();
4381
4382    // C++ [temp.arg.nontype]p1:
4383    //
4384    //   A template-argument for a non-type, non-template
4385    //   template-parameter shall be one of: [...]
4386    //
4387    //     -- the address of an object or function with external
4388    //        linkage, including function templates and function
4389    //        template-ids but excluding non-static class members,
4390    //        expressed as & id-expression where the & is optional if
4391    //        the name refers to a function or array, or if the
4392    //        corresponding template-parameter is a reference; or
4393
4394    // In C++98/03 mode, give an extension warning on any extra parentheses.
4395    // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
4396    bool ExtraParens = false;
4397    while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
4398      if (!Invalid && !ExtraParens) {
4399        S.Diag(Arg->getLocStart(),
4400               S.getLangOpts().CPlusPlus11
4401                   ? diag::warn_cxx98_compat_template_arg_extra_parens
4402                   : diag::ext_template_arg_extra_parens)
4403            << Arg->getSourceRange();
4404        ExtraParens = true;
4405      }
4406
4407      Arg = Parens->getSubExpr();
4408    }
4409
4410    while (SubstNonTypeTemplateParmExpr *subst =
4411               dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4412      Arg = subst->getReplacement()->IgnoreImpCasts();
4413
4414    if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4415      if (UnOp->getOpcode() == UO_AddrOf) {
4416        Arg = UnOp->getSubExpr();
4417        AddressTaken = true;
4418        AddrOpLoc = UnOp->getOperatorLoc();
4419      }
4420    }
4421
4422    while (SubstNonTypeTemplateParmExpr *subst =
4423               dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4424      Arg = subst->getReplacement()->IgnoreImpCasts();
4425  }
4426
4427  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg);
4428  ValueDecl *Entity = DRE ? DRE->getDecl() : nullptr;
4429
4430  // If our parameter has pointer type, check for a null template value.
4431  if (ParamType->isPointerType() || ParamType->isNullPtrType()) {
4432    NullPointerValueKind NPV;
4433    // dllimport'd entities aren't constant but are available inside of template
4434    // arguments.
4435    if (Entity && Entity->hasAttr<DLLImportAttr>())
4436      NPV = NPV_NotNullPointer;
4437    else
4438      NPV = isNullPointerValueTemplateArgument(S, Param, ParamType, ArgIn);
4439    switch (NPV) {
4440    case NPV_NullPointer:
4441      S.Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
4442      Converted = TemplateArgument(ParamType, /*isNullPtr=*/true);
4443      return false;
4444
4445    case NPV_Error:
4446      return true;
4447
4448    case NPV_NotNullPointer:
4449      break;
4450    }
4451  }
4452
4453  // Stop checking the precise nature of the argument if it is value dependent,
4454  // it should be checked when instantiated.
4455  if (Arg->isValueDependent()) {
4456    Converted = TemplateArgument(ArgIn);
4457    return false;
4458  }
4459
4460  if (isa<CXXUuidofExpr>(Arg)) {
4461    if (CheckTemplateArgumentIsCompatibleWithParameter(S, Param, ParamType,
4462                                                       ArgIn, Arg, ArgType))
4463      return true;
4464
4465    Converted = TemplateArgument(ArgIn);
4466    return false;
4467  }
4468
4469  if (!DRE) {
4470    S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
4471    << Arg->getSourceRange();
4472    S.Diag(Param->getLocation(), diag::note_template_param_here);
4473    return true;
4474  }
4475
4476  // Cannot refer to non-static data members
4477  if (isa<FieldDecl>(Entity) || isa<IndirectFieldDecl>(Entity)) {
4478    S.Diag(Arg->getLocStart(), diag::err_template_arg_field)
4479      << Entity << Arg->getSourceRange();
4480    S.Diag(Param->getLocation(), diag::note_template_param_here);
4481    return true;
4482  }
4483
4484  // Cannot refer to non-static member functions
4485  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Entity)) {
4486    if (!Method->isStatic()) {
4487      S.Diag(Arg->getLocStart(), diag::err_template_arg_method)
4488        << Method << Arg->getSourceRange();
4489      S.Diag(Param->getLocation(), diag::note_template_param_here);
4490      return true;
4491    }
4492  }
4493
4494  FunctionDecl *Func = dyn_cast<FunctionDecl>(Entity);
4495  VarDecl *Var = dyn_cast<VarDecl>(Entity);
4496
4497  // A non-type template argument must refer to an object or function.
4498  if (!Func && !Var) {
4499    // We found something, but we don't know specifically what it is.
4500    S.Diag(Arg->getLocStart(), diag::err_template_arg_not_object_or_func)
4501      << Arg->getSourceRange();
4502    S.Diag(DRE->getDecl()->getLocation(), diag::note_template_arg_refers_here);
4503    return true;
4504  }
4505
4506  // Address / reference template args must have external linkage in C++98.
4507  if (Entity->getFormalLinkage() == InternalLinkage) {
4508    S.Diag(Arg->getLocStart(), S.getLangOpts().CPlusPlus11 ?
4509             diag::warn_cxx98_compat_template_arg_object_internal :
4510             diag::ext_template_arg_object_internal)
4511      << !Func << Entity << Arg->getSourceRange();
4512    S.Diag(Entity->getLocation(), diag::note_template_arg_internal_object)
4513      << !Func;
4514  } else if (!Entity->hasLinkage()) {
4515    S.Diag(Arg->getLocStart(), diag::err_template_arg_object_no_linkage)
4516      << !Func << Entity << Arg->getSourceRange();
4517    S.Diag(Entity->getLocation(), diag::note_template_arg_internal_object)
4518      << !Func;
4519    return true;
4520  }
4521
4522  if (Func) {
4523    // If the template parameter has pointer type, the function decays.
4524    if (ParamType->isPointerType() && !AddressTaken)
4525      ArgType = S.Context.getPointerType(Func->getType());
4526    else if (AddressTaken && ParamType->isReferenceType()) {
4527      // If we originally had an address-of operator, but the
4528      // parameter has reference type, complain and (if things look
4529      // like they will work) drop the address-of operator.
4530      if (!S.Context.hasSameUnqualifiedType(Func->getType(),
4531                                            ParamType.getNonReferenceType())) {
4532        S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4533          << ParamType;
4534        S.Diag(Param->getLocation(), diag::note_template_param_here);
4535        return true;
4536      }
4537
4538      S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4539        << ParamType
4540        << FixItHint::CreateRemoval(AddrOpLoc);
4541      S.Diag(Param->getLocation(), diag::note_template_param_here);
4542
4543      ArgType = Func->getType();
4544    }
4545  } else {
4546    // A value of reference type is not an object.
4547    if (Var->getType()->isReferenceType()) {
4548      S.Diag(Arg->getLocStart(),
4549             diag::err_template_arg_reference_var)
4550        << Var->getType() << Arg->getSourceRange();
4551      S.Diag(Param->getLocation(), diag::note_template_param_here);
4552      return true;
4553    }
4554
4555    // A template argument must have static storage duration.
4556    if (Var->getTLSKind()) {
4557      S.Diag(Arg->getLocStart(), diag::err_template_arg_thread_local)
4558        << Arg->getSourceRange();
4559      S.Diag(Var->getLocation(), diag::note_template_arg_refers_here);
4560      return true;
4561    }
4562
4563    // If the template parameter has pointer type, we must have taken
4564    // the address of this object.
4565    if (ParamType->isReferenceType()) {
4566      if (AddressTaken) {
4567        // If we originally had an address-of operator, but the
4568        // parameter has reference type, complain and (if things look
4569        // like they will work) drop the address-of operator.
4570        if (!S.Context.hasSameUnqualifiedType(Var->getType(),
4571                                            ParamType.getNonReferenceType())) {
4572          S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4573            << ParamType;
4574          S.Diag(Param->getLocation(), diag::note_template_param_here);
4575          return true;
4576        }
4577
4578        S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4579          << ParamType
4580          << FixItHint::CreateRemoval(AddrOpLoc);
4581        S.Diag(Param->getLocation(), diag::note_template_param_here);
4582
4583        ArgType = Var->getType();
4584      }
4585    } else if (!AddressTaken && ParamType->isPointerType()) {
4586      if (Var->getType()->isArrayType()) {
4587        // Array-to-pointer decay.
4588        ArgType = S.Context.getArrayDecayedType(Var->getType());
4589      } else {
4590        // If the template parameter has pointer type but the address of
4591        // this object was not taken, complain and (possibly) recover by
4592        // taking the address of the entity.
4593        ArgType = S.Context.getPointerType(Var->getType());
4594        if (!S.Context.hasSameUnqualifiedType(ArgType, ParamType)) {
4595          S.Diag(Arg->getLocStart(), diag::err_template_arg_not_address_of)
4596            << ParamType;
4597          S.Diag(Param->getLocation(), diag::note_template_param_here);
4598          return true;
4599        }
4600
4601        S.Diag(Arg->getLocStart(), diag::err_template_arg_not_address_of)
4602          << ParamType
4603          << FixItHint::CreateInsertion(Arg->getLocStart(), "&");
4604
4605        S.Diag(Param->getLocation(), diag::note_template_param_here);
4606      }
4607    }
4608  }
4609
4610  if (CheckTemplateArgumentIsCompatibleWithParameter(S, Param, ParamType, ArgIn,
4611                                                     Arg, ArgType))
4612    return true;
4613
4614  // Create the template argument.
4615  Converted = TemplateArgument(cast<ValueDecl>(Entity->getCanonicalDecl()),
4616                               ParamType->isReferenceType());
4617  S.MarkAnyDeclReferenced(Arg->getLocStart(), Entity, false);
4618  return false;
4619}
4620
4621/// \brief Checks whether the given template argument is a pointer to
4622/// member constant according to C++ [temp.arg.nontype]p1.
4623static bool CheckTemplateArgumentPointerToMember(Sema &S,
4624                                                 NonTypeTemplateParmDecl *Param,
4625                                                 QualType ParamType,
4626                                                 Expr *&ResultArg,
4627                                                 TemplateArgument &Converted) {
4628  bool Invalid = false;
4629
4630  // Check for a null pointer value.
4631  Expr *Arg = ResultArg;
4632  switch (isNullPointerValueTemplateArgument(S, Param, ParamType, Arg)) {
4633  case NPV_Error:
4634    return true;
4635  case NPV_NullPointer:
4636    S.Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
4637    Converted = TemplateArgument(ParamType, /*isNullPtr*/true);
4638    if (S.Context.getTargetInfo().getCXXABI().isMicrosoft())
4639      S.RequireCompleteType(Arg->getExprLoc(), ParamType, 0);
4640    return false;
4641  case NPV_NotNullPointer:
4642    break;
4643  }
4644
4645  bool ObjCLifetimeConversion;
4646  if (S.IsQualificationConversion(Arg->getType(),
4647                                  ParamType.getNonReferenceType(),
4648                                  false, ObjCLifetimeConversion)) {
4649    Arg = S.ImpCastExprToType(Arg, ParamType, CK_NoOp,
4650                              Arg->getValueKind()).get();
4651    ResultArg = Arg;
4652  } else if (!S.Context.hasSameUnqualifiedType(Arg->getType(),
4653                ParamType.getNonReferenceType())) {
4654    // We can't perform this conversion.
4655    S.Diag(Arg->getLocStart(), diag::err_template_arg_not_convertible)
4656      << Arg->getType() << ParamType << Arg->getSourceRange();
4657    S.Diag(Param->getLocation(), diag::note_template_param_here);
4658    return true;
4659  }
4660
4661  // See through any implicit casts we added to fix the type.
4662  while (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(Arg))
4663    Arg = Cast->getSubExpr();
4664
4665  // C++ [temp.arg.nontype]p1:
4666  //
4667  //   A template-argument for a non-type, non-template
4668  //   template-parameter shall be one of: [...]
4669  //
4670  //     -- a pointer to member expressed as described in 5.3.1.
4671  DeclRefExpr *DRE = nullptr;
4672
4673  // In C++98/03 mode, give an extension warning on any extra parentheses.
4674  // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
4675  bool ExtraParens = false;
4676  while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
4677    if (!Invalid && !ExtraParens) {
4678      S.Diag(Arg->getLocStart(),
4679             S.getLangOpts().CPlusPlus11 ?
4680               diag::warn_cxx98_compat_template_arg_extra_parens :
4681               diag::ext_template_arg_extra_parens)
4682        << Arg->getSourceRange();
4683      ExtraParens = true;
4684    }
4685
4686    Arg = Parens->getSubExpr();
4687  }
4688
4689  while (SubstNonTypeTemplateParmExpr *subst =
4690           dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4691    Arg = subst->getReplacement()->IgnoreImpCasts();
4692
4693  // A pointer-to-member constant written &Class::member.
4694  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4695    if (UnOp->getOpcode() == UO_AddrOf) {
4696      DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr());
4697      if (DRE && !DRE->getQualifier())
4698        DRE = nullptr;
4699    }
4700  }
4701  // A constant of pointer-to-member type.
4702  else if ((DRE = dyn_cast<DeclRefExpr>(Arg))) {
4703    if (ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl())) {
4704      if (VD->getType()->isMemberPointerType()) {
4705        if (isa<NonTypeTemplateParmDecl>(VD)) {
4706          if (Arg->isTypeDependent() || Arg->isValueDependent()) {
4707            Converted = TemplateArgument(Arg);
4708          } else {
4709            VD = cast<ValueDecl>(VD->getCanonicalDecl());
4710            Converted = TemplateArgument(VD, /*isReferenceParam*/false);
4711          }
4712          return Invalid;
4713        }
4714      }
4715    }
4716
4717    DRE = nullptr;
4718  }
4719
4720  if (!DRE)
4721    return S.Diag(Arg->getLocStart(),
4722                  diag::err_template_arg_not_pointer_to_member_form)
4723      << Arg->getSourceRange();
4724
4725  if (isa<FieldDecl>(DRE->getDecl()) ||
4726      isa<IndirectFieldDecl>(DRE->getDecl()) ||
4727      isa<CXXMethodDecl>(DRE->getDecl())) {
4728    assert((isa<FieldDecl>(DRE->getDecl()) ||
4729            isa<IndirectFieldDecl>(DRE->getDecl()) ||
4730            !cast<CXXMethodDecl>(DRE->getDecl())->isStatic()) &&
4731           "Only non-static member pointers can make it here");
4732
4733    // Okay: this is the address of a non-static member, and therefore
4734    // a member pointer constant.
4735    if (Arg->isTypeDependent() || Arg->isValueDependent()) {
4736      Converted = TemplateArgument(Arg);
4737    } else {
4738      ValueDecl *D = cast<ValueDecl>(DRE->getDecl()->getCanonicalDecl());
4739      Converted = TemplateArgument(D, /*isReferenceParam*/false);
4740    }
4741    return Invalid;
4742  }
4743
4744  // We found something else, but we don't know specifically what it is.
4745  S.Diag(Arg->getLocStart(),
4746         diag::err_template_arg_not_pointer_to_member_form)
4747    << Arg->getSourceRange();
4748  S.Diag(DRE->getDecl()->getLocation(), diag::note_template_arg_refers_here);
4749  return true;
4750}
4751
4752/// \brief Check a template argument against its corresponding
4753/// non-type template parameter.
4754///
4755/// This routine implements the semantics of C++ [temp.arg.nontype].
4756/// If an error occurred, it returns ExprError(); otherwise, it
4757/// returns the converted template argument. \p
4758/// InstantiatedParamType is the type of the non-type template
4759/// parameter after it has been instantiated.
4760ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
4761                                       QualType InstantiatedParamType, Expr *Arg,
4762                                       TemplateArgument &Converted,
4763                                       CheckTemplateArgumentKind CTAK) {
4764  SourceLocation StartLoc = Arg->getLocStart();
4765
4766  // If either the parameter has a dependent type or the argument is
4767  // type-dependent, there's nothing we can check now.
4768  if (InstantiatedParamType->isDependentType() || Arg->isTypeDependent()) {
4769    // FIXME: Produce a cloned, canonical expression?
4770    Converted = TemplateArgument(Arg);
4771    return Arg;
4772  }
4773
4774  // C++ [temp.arg.nontype]p5:
4775  //   The following conversions are performed on each expression used
4776  //   as a non-type template-argument. If a non-type
4777  //   template-argument cannot be converted to the type of the
4778  //   corresponding template-parameter then the program is
4779  //   ill-formed.
4780  QualType ParamType = InstantiatedParamType;
4781  if (ParamType->isIntegralOrEnumerationType()) {
4782    // C++11:
4783    //   -- for a non-type template-parameter of integral or
4784    //      enumeration type, conversions permitted in a converted
4785    //      constant expression are applied.
4786    //
4787    // C++98:
4788    //   -- for a non-type template-parameter of integral or
4789    //      enumeration type, integral promotions (4.5) and integral
4790    //      conversions (4.7) are applied.
4791
4792    if (CTAK == CTAK_Deduced &&
4793        !Context.hasSameUnqualifiedType(ParamType, Arg->getType())) {
4794      // C++ [temp.deduct.type]p17:
4795      //   If, in the declaration of a function template with a non-type
4796      //   template-parameter, the non-type template-parameter is used
4797      //   in an expression in the function parameter-list and, if the
4798      //   corresponding template-argument is deduced, the
4799      //   template-argument type shall match the type of the
4800      //   template-parameter exactly, except that a template-argument
4801      //   deduced from an array bound may be of any integral type.
4802      Diag(StartLoc, diag::err_deduced_non_type_template_arg_type_mismatch)
4803        << Arg->getType().getUnqualifiedType()
4804        << ParamType.getUnqualifiedType();
4805      Diag(Param->getLocation(), diag::note_template_param_here);
4806      return ExprError();
4807    }
4808
4809    if (getLangOpts().CPlusPlus11) {
4810      // We can't check arbitrary value-dependent arguments.
4811      // FIXME: If there's no viable conversion to the template parameter type,
4812      // we should be able to diagnose that prior to instantiation.
4813      if (Arg->isValueDependent()) {
4814        Converted = TemplateArgument(Arg);
4815        return Arg;
4816      }
4817
4818      // C++ [temp.arg.nontype]p1:
4819      //   A template-argument for a non-type, non-template template-parameter
4820      //   shall be one of:
4821      //
4822      //     -- for a non-type template-parameter of integral or enumeration
4823      //        type, a converted constant expression of the type of the
4824      //        template-parameter; or
4825      llvm::APSInt Value;
4826      ExprResult ArgResult =
4827        CheckConvertedConstantExpression(Arg, ParamType, Value,
4828                                         CCEK_TemplateArg);
4829      if (ArgResult.isInvalid())
4830        return ExprError();
4831
4832      // Widen the argument value to sizeof(parameter type). This is almost
4833      // always a no-op, except when the parameter type is bool. In
4834      // that case, this may extend the argument from 1 bit to 8 bits.
4835      QualType IntegerType = ParamType;
4836      if (const EnumType *Enum = IntegerType->getAs<EnumType>())
4837        IntegerType = Enum->getDecl()->getIntegerType();
4838      Value = Value.extOrTrunc(Context.getTypeSize(IntegerType));
4839
4840      Converted = TemplateArgument(Context, Value,
4841                                   Context.getCanonicalType(ParamType));
4842      return ArgResult;
4843    }
4844
4845    ExprResult ArgResult = DefaultLvalueConversion(Arg);
4846    if (ArgResult.isInvalid())
4847      return ExprError();
4848    Arg = ArgResult.get();
4849
4850    QualType ArgType = Arg->getType();
4851
4852    // C++ [temp.arg.nontype]p1:
4853    //   A template-argument for a non-type, non-template
4854    //   template-parameter shall be one of:
4855    //
4856    //     -- an integral constant-expression of integral or enumeration
4857    //        type; or
4858    //     -- the name of a non-type template-parameter; or
4859    SourceLocation NonConstantLoc;
4860    llvm::APSInt Value;
4861    if (!ArgType->isIntegralOrEnumerationType()) {
4862      Diag(Arg->getLocStart(),
4863           diag::err_template_arg_not_integral_or_enumeral)
4864        << ArgType << Arg->getSourceRange();
4865      Diag(Param->getLocation(), diag::note_template_param_here);
4866      return ExprError();
4867    } else if (!Arg->isValueDependent()) {
4868      class TmplArgICEDiagnoser : public VerifyICEDiagnoser {
4869        QualType T;
4870
4871      public:
4872        TmplArgICEDiagnoser(QualType T) : T(T) { }
4873
4874        void diagnoseNotICE(Sema &S, SourceLocation Loc,
4875                            SourceRange SR) override {
4876          S.Diag(Loc, diag::err_template_arg_not_ice) << T << SR;
4877        }
4878      } Diagnoser(ArgType);
4879
4880      Arg = VerifyIntegerConstantExpression(Arg, &Value, Diagnoser,
4881                                            false).get();
4882      if (!Arg)
4883        return ExprError();
4884    }
4885
4886    // From here on out, all we care about are the unqualified forms
4887    // of the parameter and argument types.
4888    ParamType = ParamType.getUnqualifiedType();
4889    ArgType = ArgType.getUnqualifiedType();
4890
4891    // Try to convert the argument to the parameter's type.
4892    if (Context.hasSameType(ParamType, ArgType)) {
4893      // Okay: no conversion necessary
4894    } else if (ParamType->isBooleanType()) {
4895      // This is an integral-to-boolean conversion.
4896      Arg = ImpCastExprToType(Arg, ParamType, CK_IntegralToBoolean).get();
4897    } else if (IsIntegralPromotion(Arg, ArgType, ParamType) ||
4898               !ParamType->isEnumeralType()) {
4899      // This is an integral promotion or conversion.
4900      Arg = ImpCastExprToType(Arg, ParamType, CK_IntegralCast).get();
4901    } else {
4902      // We can't perform this conversion.
4903      Diag(Arg->getLocStart(),
4904           diag::err_template_arg_not_convertible)
4905        << Arg->getType() << InstantiatedParamType << Arg->getSourceRange();
4906      Diag(Param->getLocation(), diag::note_template_param_here);
4907      return ExprError();
4908    }
4909
4910    // Add the value of this argument to the list of converted
4911    // arguments. We use the bitwidth and signedness of the template
4912    // parameter.
4913    if (Arg->isValueDependent()) {
4914      // The argument is value-dependent. Create a new
4915      // TemplateArgument with the converted expression.
4916      Converted = TemplateArgument(Arg);
4917      return Arg;
4918    }
4919
4920    QualType IntegerType = Context.getCanonicalType(ParamType);
4921    if (const EnumType *Enum = IntegerType->getAs<EnumType>())
4922      IntegerType = Context.getCanonicalType(Enum->getDecl()->getIntegerType());
4923
4924    if (ParamType->isBooleanType()) {
4925      // Value must be zero or one.
4926      Value = Value != 0;
4927      unsigned AllowedBits = Context.getTypeSize(IntegerType);
4928      if (Value.getBitWidth() != AllowedBits)
4929        Value = Value.extOrTrunc(AllowedBits);
4930      Value.setIsSigned(IntegerType->isSignedIntegerOrEnumerationType());
4931    } else {
4932      llvm::APSInt OldValue = Value;
4933
4934      // Coerce the template argument's value to the value it will have
4935      // based on the template parameter's type.
4936      unsigned AllowedBits = Context.getTypeSize(IntegerType);
4937      if (Value.getBitWidth() != AllowedBits)
4938        Value = Value.extOrTrunc(AllowedBits);
4939      Value.setIsSigned(IntegerType->isSignedIntegerOrEnumerationType());
4940
4941      // Complain if an unsigned parameter received a negative value.
4942      if (IntegerType->isUnsignedIntegerOrEnumerationType()
4943               && (OldValue.isSigned() && OldValue.isNegative())) {
4944        Diag(Arg->getLocStart(), diag::warn_template_arg_negative)
4945          << OldValue.toString(10) << Value.toString(10) << Param->getType()
4946          << Arg->getSourceRange();
4947        Diag(Param->getLocation(), diag::note_template_param_here);
4948      }
4949
4950      // Complain if we overflowed the template parameter's type.
4951      unsigned RequiredBits;
4952      if (IntegerType->isUnsignedIntegerOrEnumerationType())
4953        RequiredBits = OldValue.getActiveBits();
4954      else if (OldValue.isUnsigned())
4955        RequiredBits = OldValue.getActiveBits() + 1;
4956      else
4957        RequiredBits = OldValue.getMinSignedBits();
4958      if (RequiredBits > AllowedBits) {
4959        Diag(Arg->getLocStart(),
4960             diag::warn_template_arg_too_large)
4961          << OldValue.toString(10) << Value.toString(10) << Param->getType()
4962          << Arg->getSourceRange();
4963        Diag(Param->getLocation(), diag::note_template_param_here);
4964      }
4965    }
4966
4967    Converted = TemplateArgument(Context, Value,
4968                                 ParamType->isEnumeralType()
4969                                   ? Context.getCanonicalType(ParamType)
4970                                   : IntegerType);
4971    return Arg;
4972  }
4973
4974  QualType ArgType = Arg->getType();
4975  DeclAccessPair FoundResult; // temporary for ResolveOverloadedFunction
4976
4977  // Handle pointer-to-function, reference-to-function, and
4978  // pointer-to-member-function all in (roughly) the same way.
4979  if (// -- For a non-type template-parameter of type pointer to
4980      //    function, only the function-to-pointer conversion (4.3) is
4981      //    applied. If the template-argument represents a set of
4982      //    overloaded functions (or a pointer to such), the matching
4983      //    function is selected from the set (13.4).
4984      (ParamType->isPointerType() &&
4985       ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType()) ||
4986      // -- For a non-type template-parameter of type reference to
4987      //    function, no conversions apply. If the template-argument
4988      //    represents a set of overloaded functions, the matching
4989      //    function is selected from the set (13.4).
4990      (ParamType->isReferenceType() &&
4991       ParamType->getAs<ReferenceType>()->getPointeeType()->isFunctionType()) ||
4992      // -- For a non-type template-parameter of type pointer to
4993      //    member function, no conversions apply. If the
4994      //    template-argument represents a set of overloaded member
4995      //    functions, the matching member function is selected from
4996      //    the set (13.4).
4997      (ParamType->isMemberPointerType() &&
4998       ParamType->getAs<MemberPointerType>()->getPointeeType()
4999         ->isFunctionType())) {
5000
5001    if (Arg->getType() == Context.OverloadTy) {
5002      if (FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(Arg, ParamType,
5003                                                                true,
5004                                                                FoundResult)) {
5005        if (DiagnoseUseOfDecl(Fn, Arg->getLocStart()))
5006          return ExprError();
5007
5008        Arg = FixOverloadedFunctionReference(Arg, FoundResult, Fn);
5009        ArgType = Arg->getType();
5010      } else
5011        return ExprError();
5012    }
5013
5014    if (!ParamType->isMemberPointerType()) {
5015      if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5016                                                         ParamType,
5017                                                         Arg, Converted))
5018        return ExprError();
5019      return Arg;
5020    }
5021
5022    if (CheckTemplateArgumentPointerToMember(*this, Param, ParamType, Arg,
5023                                             Converted))
5024      return ExprError();
5025    return Arg;
5026  }
5027
5028  if (ParamType->isPointerType()) {
5029    //   -- for a non-type template-parameter of type pointer to
5030    //      object, qualification conversions (4.4) and the
5031    //      array-to-pointer conversion (4.2) are applied.
5032    // C++0x also allows a value of std::nullptr_t.
5033    assert(ParamType->getPointeeType()->isIncompleteOrObjectType() &&
5034           "Only object pointers allowed here");
5035
5036    if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5037                                                       ParamType,
5038                                                       Arg, Converted))
5039      return ExprError();
5040    return Arg;
5041  }
5042
5043  if (const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>()) {
5044    //   -- For a non-type template-parameter of type reference to
5045    //      object, no conversions apply. The type referred to by the
5046    //      reference may be more cv-qualified than the (otherwise
5047    //      identical) type of the template-argument. The
5048    //      template-parameter is bound directly to the
5049    //      template-argument, which must be an lvalue.
5050    assert(ParamRefType->getPointeeType()->isIncompleteOrObjectType() &&
5051           "Only object references allowed here");
5052
5053    if (Arg->getType() == Context.OverloadTy) {
5054      if (FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(Arg,
5055                                                 ParamRefType->getPointeeType(),
5056                                                                true,
5057                                                                FoundResult)) {
5058        if (DiagnoseUseOfDecl(Fn, Arg->getLocStart()))
5059          return ExprError();
5060
5061        Arg = FixOverloadedFunctionReference(Arg, FoundResult, Fn);
5062        ArgType = Arg->getType();
5063      } else
5064        return ExprError();
5065    }
5066
5067    if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5068                                                       ParamType,
5069                                                       Arg, Converted))
5070      return ExprError();
5071    return Arg;
5072  }
5073
5074  // Deal with parameters of type std::nullptr_t.
5075  if (ParamType->isNullPtrType()) {
5076    if (Arg->isTypeDependent() || Arg->isValueDependent()) {
5077      Converted = TemplateArgument(Arg);
5078      return Arg;
5079    }
5080
5081    switch (isNullPointerValueTemplateArgument(*this, Param, ParamType, Arg)) {
5082    case NPV_NotNullPointer:
5083      Diag(Arg->getExprLoc(), diag::err_template_arg_not_convertible)
5084        << Arg->getType() << ParamType;
5085      Diag(Param->getLocation(), diag::note_template_param_here);
5086      return ExprError();
5087
5088    case NPV_Error:
5089      return ExprError();
5090
5091    case NPV_NullPointer:
5092      Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
5093      Converted = TemplateArgument(ParamType, /*isNullPtr*/true);
5094      return Arg;
5095    }
5096  }
5097
5098  //     -- For a non-type template-parameter of type pointer to data
5099  //        member, qualification conversions (4.4) are applied.
5100  assert(ParamType->isMemberPointerType() && "Only pointers to members remain");
5101
5102  if (CheckTemplateArgumentPointerToMember(*this, Param, ParamType, Arg,
5103                                           Converted))
5104    return ExprError();
5105  return Arg;
5106}
5107
5108/// \brief Check a template argument against its corresponding
5109/// template template parameter.
5110///
5111/// This routine implements the semantics of C++ [temp.arg.template].
5112/// It returns true if an error occurred, and false otherwise.
5113bool Sema::CheckTemplateArgument(TemplateTemplateParmDecl *Param,
5114                                 TemplateArgumentLoc &Arg,
5115                                 unsigned ArgumentPackIndex) {
5116  TemplateName Name = Arg.getArgument().getAsTemplateOrTemplatePattern();
5117  TemplateDecl *Template = Name.getAsTemplateDecl();
5118  if (!Template) {
5119    // Any dependent template name is fine.
5120    assert(Name.isDependent() && "Non-dependent template isn't a declaration?");
5121    return false;
5122  }
5123
5124  // C++0x [temp.arg.template]p1:
5125  //   A template-argument for a template template-parameter shall be
5126  //   the name of a class template or an alias template, expressed as an
5127  //   id-expression. When the template-argument names a class template, only
5128  //   primary class templates are considered when matching the
5129  //   template template argument with the corresponding parameter;
5130  //   partial specializations are not considered even if their
5131  //   parameter lists match that of the template template parameter.
5132  //
5133  // Note that we also allow template template parameters here, which
5134  // will happen when we are dealing with, e.g., class template
5135  // partial specializations.
5136  if (!isa<ClassTemplateDecl>(Template) &&
5137      !isa<TemplateTemplateParmDecl>(Template) &&
5138      !isa<TypeAliasTemplateDecl>(Template)) {
5139    assert(isa<FunctionTemplateDecl>(Template) &&
5140           "Only function templates are possible here");
5141    Diag(Arg.getLocation(), diag::err_template_arg_not_class_template);
5142    Diag(Template->getLocation(), diag::note_template_arg_refers_here_func)
5143      << Template;
5144  }
5145
5146  TemplateParameterList *Params = Param->getTemplateParameters();
5147  if (Param->isExpandedParameterPack())
5148    Params = Param->getExpansionTemplateParameters(ArgumentPackIndex);
5149
5150  return !TemplateParameterListsAreEqual(Template->getTemplateParameters(),
5151                                         Params,
5152                                         true,
5153                                         TPL_TemplateTemplateArgumentMatch,
5154                                         Arg.getLocation());
5155}
5156
5157/// \brief Given a non-type template argument that refers to a
5158/// declaration and the type of its corresponding non-type template
5159/// parameter, produce an expression that properly refers to that
5160/// declaration.
5161ExprResult
5162Sema::BuildExpressionFromDeclTemplateArgument(const TemplateArgument &Arg,
5163                                              QualType ParamType,
5164                                              SourceLocation Loc) {
5165  // C++ [temp.param]p8:
5166  //
5167  //   A non-type template-parameter of type "array of T" or
5168  //   "function returning T" is adjusted to be of type "pointer to
5169  //   T" or "pointer to function returning T", respectively.
5170  if (ParamType->isArrayType())
5171    ParamType = Context.getArrayDecayedType(ParamType);
5172  else if (ParamType->isFunctionType())
5173    ParamType = Context.getPointerType(ParamType);
5174
5175  // For a NULL non-type template argument, return nullptr casted to the
5176  // parameter's type.
5177  if (Arg.getKind() == TemplateArgument::NullPtr) {
5178    return ImpCastExprToType(
5179             new (Context) CXXNullPtrLiteralExpr(Context.NullPtrTy, Loc),
5180                             ParamType,
5181                             ParamType->getAs<MemberPointerType>()
5182                               ? CK_NullToMemberPointer
5183                               : CK_NullToPointer);
5184  }
5185  assert(Arg.getKind() == TemplateArgument::Declaration &&
5186         "Only declaration template arguments permitted here");
5187
5188  ValueDecl *VD = cast<ValueDecl>(Arg.getAsDecl());
5189
5190  if (VD->getDeclContext()->isRecord() &&
5191      (isa<CXXMethodDecl>(VD) || isa<FieldDecl>(VD) ||
5192       isa<IndirectFieldDecl>(VD))) {
5193    // If the value is a class member, we might have a pointer-to-member.
5194    // Determine whether the non-type template template parameter is of
5195    // pointer-to-member type. If so, we need to build an appropriate
5196    // expression for a pointer-to-member, since a "normal" DeclRefExpr
5197    // would refer to the member itself.
5198    if (ParamType->isMemberPointerType()) {
5199      QualType ClassType
5200        = Context.getTypeDeclType(cast<RecordDecl>(VD->getDeclContext()));
5201      NestedNameSpecifier *Qualifier
5202        = NestedNameSpecifier::Create(Context, nullptr, false,
5203                                      ClassType.getTypePtr());
5204      CXXScopeSpec SS;
5205      SS.MakeTrivial(Context, Qualifier, Loc);
5206
5207      // The actual value-ness of this is unimportant, but for
5208      // internal consistency's sake, references to instance methods
5209      // are r-values.
5210      ExprValueKind VK = VK_LValue;
5211      if (isa<CXXMethodDecl>(VD) && cast<CXXMethodDecl>(VD)->isInstance())
5212        VK = VK_RValue;
5213
5214      ExprResult RefExpr = BuildDeclRefExpr(VD,
5215                                            VD->getType().getNonReferenceType(),
5216                                            VK,
5217                                            Loc,
5218                                            &SS);
5219      if (RefExpr.isInvalid())
5220        return ExprError();
5221
5222      RefExpr = CreateBuiltinUnaryOp(Loc, UO_AddrOf, RefExpr.get());
5223
5224      // We might need to perform a trailing qualification conversion, since
5225      // the element type on the parameter could be more qualified than the
5226      // element type in the expression we constructed.
5227      bool ObjCLifetimeConversion;
5228      if (IsQualificationConversion(((Expr*) RefExpr.get())->getType(),
5229                                    ParamType.getUnqualifiedType(), false,
5230                                    ObjCLifetimeConversion))
5231        RefExpr = ImpCastExprToType(RefExpr.get(), ParamType.getUnqualifiedType(), CK_NoOp);
5232
5233      assert(!RefExpr.isInvalid() &&
5234             Context.hasSameType(((Expr*) RefExpr.get())->getType(),
5235                                 ParamType.getUnqualifiedType()));
5236      return RefExpr;
5237    }
5238  }
5239
5240  QualType T = VD->getType().getNonReferenceType();
5241
5242  if (ParamType->isPointerType()) {
5243    // When the non-type template parameter is a pointer, take the
5244    // address of the declaration.
5245    ExprResult RefExpr = BuildDeclRefExpr(VD, T, VK_LValue, Loc);
5246    if (RefExpr.isInvalid())
5247      return ExprError();
5248
5249    if (T->isFunctionType() || T->isArrayType()) {
5250      // Decay functions and arrays.
5251      RefExpr = DefaultFunctionArrayConversion(RefExpr.get());
5252      if (RefExpr.isInvalid())
5253        return ExprError();
5254
5255      return RefExpr;
5256    }
5257
5258    // Take the address of everything else
5259    return CreateBuiltinUnaryOp(Loc, UO_AddrOf, RefExpr.get());
5260  }
5261
5262  ExprValueKind VK = VK_RValue;
5263
5264  // If the non-type template parameter has reference type, qualify the
5265  // resulting declaration reference with the extra qualifiers on the
5266  // type that the reference refers to.
5267  if (const ReferenceType *TargetRef = ParamType->getAs<ReferenceType>()) {
5268    VK = VK_LValue;
5269    T = Context.getQualifiedType(T,
5270                              TargetRef->getPointeeType().getQualifiers());
5271  } else if (isa<FunctionDecl>(VD)) {
5272    // References to functions are always lvalues.
5273    VK = VK_LValue;
5274  }
5275
5276  return BuildDeclRefExpr(VD, T, VK, Loc);
5277}
5278
5279/// \brief Construct a new expression that refers to the given
5280/// integral template argument with the given source-location
5281/// information.
5282///
5283/// This routine takes care of the mapping from an integral template
5284/// argument (which may have any integral type) to the appropriate
5285/// literal value.
5286ExprResult
5287Sema::BuildExpressionFromIntegralTemplateArgument(const TemplateArgument &Arg,
5288                                                  SourceLocation Loc) {
5289  assert(Arg.getKind() == TemplateArgument::Integral &&
5290         "Operation is only valid for integral template arguments");
5291  QualType OrigT = Arg.getIntegralType();
5292
5293  // If this is an enum type that we're instantiating, we need to use an integer
5294  // type the same size as the enumerator.  We don't want to build an
5295  // IntegerLiteral with enum type.  The integer type of an enum type can be of
5296  // any integral type with C++11 enum classes, make sure we create the right
5297  // type of literal for it.
5298  QualType T = OrigT;
5299  if (const EnumType *ET = OrigT->getAs<EnumType>())
5300    T = ET->getDecl()->getIntegerType();
5301
5302  Expr *E;
5303  if (T->isAnyCharacterType()) {
5304    CharacterLiteral::CharacterKind Kind;
5305    if (T->isWideCharType())
5306      Kind = CharacterLiteral::Wide;
5307    else if (T->isChar16Type())
5308      Kind = CharacterLiteral::UTF16;
5309    else if (T->isChar32Type())
5310      Kind = CharacterLiteral::UTF32;
5311    else
5312      Kind = CharacterLiteral::Ascii;
5313
5314    E = new (Context) CharacterLiteral(Arg.getAsIntegral().getZExtValue(),
5315                                       Kind, T, Loc);
5316  } else if (T->isBooleanType()) {
5317    E = new (Context) CXXBoolLiteralExpr(Arg.getAsIntegral().getBoolValue(),
5318                                         T, Loc);
5319  } else if (T->isNullPtrType()) {
5320    E = new (Context) CXXNullPtrLiteralExpr(Context.NullPtrTy, Loc);
5321  } else {
5322    E = IntegerLiteral::Create(Context, Arg.getAsIntegral(), T, Loc);
5323  }
5324
5325  if (OrigT->isEnumeralType()) {
5326    // FIXME: This is a hack. We need a better way to handle substituted
5327    // non-type template parameters.
5328    E = CStyleCastExpr::Create(Context, OrigT, VK_RValue, CK_IntegralCast, E,
5329                               nullptr,
5330                               Context.getTrivialTypeSourceInfo(OrigT, Loc),
5331                               Loc, Loc);
5332  }
5333
5334  return E;
5335}
5336
5337/// \brief Match two template parameters within template parameter lists.
5338static bool MatchTemplateParameterKind(Sema &S, NamedDecl *New, NamedDecl *Old,
5339                                       bool Complain,
5340                                     Sema::TemplateParameterListEqualKind Kind,
5341                                       SourceLocation TemplateArgLoc) {
5342  // Check the actual kind (type, non-type, template).
5343  if (Old->getKind() != New->getKind()) {
5344    if (Complain) {
5345      unsigned NextDiag = diag::err_template_param_different_kind;
5346      if (TemplateArgLoc.isValid()) {
5347        S.Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
5348        NextDiag = diag::note_template_param_different_kind;
5349      }
5350      S.Diag(New->getLocation(), NextDiag)
5351        << (Kind != Sema::TPL_TemplateMatch);
5352      S.Diag(Old->getLocation(), diag::note_template_prev_declaration)
5353        << (Kind != Sema::TPL_TemplateMatch);
5354    }
5355
5356    return false;
5357  }
5358
5359  // Check that both are parameter packs are neither are parameter packs.
5360  // However, if we are matching a template template argument to a
5361  // template template parameter, the template template parameter can have
5362  // a parameter pack where the template template argument does not.
5363  if (Old->isTemplateParameterPack() != New->isTemplateParameterPack() &&
5364      !(Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
5365        Old->isTemplateParameterPack())) {
5366    if (Complain) {
5367      unsigned NextDiag = diag::err_template_parameter_pack_non_pack;
5368      if (TemplateArgLoc.isValid()) {
5369        S.Diag(TemplateArgLoc,
5370             diag::err_template_arg_template_params_mismatch);
5371        NextDiag = diag::note_template_parameter_pack_non_pack;
5372      }
5373
5374      unsigned ParamKind = isa<TemplateTypeParmDecl>(New)? 0
5375                      : isa<NonTypeTemplateParmDecl>(New)? 1
5376                      : 2;
5377      S.Diag(New->getLocation(), NextDiag)
5378        << ParamKind << New->isParameterPack();
5379      S.Diag(Old->getLocation(), diag::note_template_parameter_pack_here)
5380        << ParamKind << Old->isParameterPack();
5381    }
5382
5383    return false;
5384  }
5385
5386  // For non-type template parameters, check the type of the parameter.
5387  if (NonTypeTemplateParmDecl *OldNTTP
5388                                    = dyn_cast<NonTypeTemplateParmDecl>(Old)) {
5389    NonTypeTemplateParmDecl *NewNTTP = cast<NonTypeTemplateParmDecl>(New);
5390
5391    // If we are matching a template template argument to a template
5392    // template parameter and one of the non-type template parameter types
5393    // is dependent, then we must wait until template instantiation time
5394    // to actually compare the arguments.
5395    if (Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
5396        (OldNTTP->getType()->isDependentType() ||
5397         NewNTTP->getType()->isDependentType()))
5398      return true;
5399
5400    if (!S.Context.hasSameType(OldNTTP->getType(), NewNTTP->getType())) {
5401      if (Complain) {
5402        unsigned NextDiag = diag::err_template_nontype_parm_different_type;
5403        if (TemplateArgLoc.isValid()) {
5404          S.Diag(TemplateArgLoc,
5405                 diag::err_template_arg_template_params_mismatch);
5406          NextDiag = diag::note_template_nontype_parm_different_type;
5407        }
5408        S.Diag(NewNTTP->getLocation(), NextDiag)
5409          << NewNTTP->getType()
5410          << (Kind != Sema::TPL_TemplateMatch);
5411        S.Diag(OldNTTP->getLocation(),
5412               diag::note_template_nontype_parm_prev_declaration)
5413          << OldNTTP->getType();
5414      }
5415
5416      return false;
5417    }
5418
5419    return true;
5420  }
5421
5422  // For template template parameters, check the template parameter types.
5423  // The template parameter lists of template template
5424  // parameters must agree.
5425  if (TemplateTemplateParmDecl *OldTTP
5426                                    = dyn_cast<TemplateTemplateParmDecl>(Old)) {
5427    TemplateTemplateParmDecl *NewTTP = cast<TemplateTemplateParmDecl>(New);
5428    return S.TemplateParameterListsAreEqual(NewTTP->getTemplateParameters(),
5429                                            OldTTP->getTemplateParameters(),
5430                                            Complain,
5431                                        (Kind == Sema::TPL_TemplateMatch
5432                                           ? Sema::TPL_TemplateTemplateParmMatch
5433                                           : Kind),
5434                                            TemplateArgLoc);
5435  }
5436
5437  return true;
5438}
5439
5440/// \brief Diagnose a known arity mismatch when comparing template argument
5441/// lists.
5442static
5443void DiagnoseTemplateParameterListArityMismatch(Sema &S,
5444                                                TemplateParameterList *New,
5445                                                TemplateParameterList *Old,
5446                                      Sema::TemplateParameterListEqualKind Kind,
5447                                                SourceLocation TemplateArgLoc) {
5448  unsigned NextDiag = diag::err_template_param_list_different_arity;
5449  if (TemplateArgLoc.isValid()) {
5450    S.Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
5451    NextDiag = diag::note_template_param_list_different_arity;
5452  }
5453  S.Diag(New->getTemplateLoc(), NextDiag)
5454    << (New->size() > Old->size())
5455    << (Kind != Sema::TPL_TemplateMatch)
5456    << SourceRange(New->getTemplateLoc(), New->getRAngleLoc());
5457  S.Diag(Old->getTemplateLoc(), diag::note_template_prev_declaration)
5458    << (Kind != Sema::TPL_TemplateMatch)
5459    << SourceRange(Old->getTemplateLoc(), Old->getRAngleLoc());
5460}
5461
5462/// \brief Determine whether the given template parameter lists are
5463/// equivalent.
5464///
5465/// \param New  The new template parameter list, typically written in the
5466/// source code as part of a new template declaration.
5467///
5468/// \param Old  The old template parameter list, typically found via
5469/// name lookup of the template declared with this template parameter
5470/// list.
5471///
5472/// \param Complain  If true, this routine will produce a diagnostic if
5473/// the template parameter lists are not equivalent.
5474///
5475/// \param Kind describes how we are to match the template parameter lists.
5476///
5477/// \param TemplateArgLoc If this source location is valid, then we
5478/// are actually checking the template parameter list of a template
5479/// argument (New) against the template parameter list of its
5480/// corresponding template template parameter (Old). We produce
5481/// slightly different diagnostics in this scenario.
5482///
5483/// \returns True if the template parameter lists are equal, false
5484/// otherwise.
5485bool
5486Sema::TemplateParameterListsAreEqual(TemplateParameterList *New,
5487                                     TemplateParameterList *Old,
5488                                     bool Complain,
5489                                     TemplateParameterListEqualKind Kind,
5490                                     SourceLocation TemplateArgLoc) {
5491  if (Old->size() != New->size() && Kind != TPL_TemplateTemplateArgumentMatch) {
5492    if (Complain)
5493      DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5494                                                 TemplateArgLoc);
5495
5496    return false;
5497  }
5498
5499  // C++0x [temp.arg.template]p3:
5500  //   A template-argument matches a template template-parameter (call it P)
5501  //   when each of the template parameters in the template-parameter-list of
5502  //   the template-argument's corresponding class template or alias template
5503  //   (call it A) matches the corresponding template parameter in the
5504  //   template-parameter-list of P. [...]
5505  TemplateParameterList::iterator NewParm = New->begin();
5506  TemplateParameterList::iterator NewParmEnd = New->end();
5507  for (TemplateParameterList::iterator OldParm = Old->begin(),
5508                                    OldParmEnd = Old->end();
5509       OldParm != OldParmEnd; ++OldParm) {
5510    if (Kind != TPL_TemplateTemplateArgumentMatch ||
5511        !(*OldParm)->isTemplateParameterPack()) {
5512      if (NewParm == NewParmEnd) {
5513        if (Complain)
5514          DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5515                                                     TemplateArgLoc);
5516
5517        return false;
5518      }
5519
5520      if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
5521                                      Kind, TemplateArgLoc))
5522        return false;
5523
5524      ++NewParm;
5525      continue;
5526    }
5527
5528    // C++0x [temp.arg.template]p3:
5529    //   [...] When P's template- parameter-list contains a template parameter
5530    //   pack (14.5.3), the template parameter pack will match zero or more
5531    //   template parameters or template parameter packs in the
5532    //   template-parameter-list of A with the same type and form as the
5533    //   template parameter pack in P (ignoring whether those template
5534    //   parameters are template parameter packs).
5535    for (; NewParm != NewParmEnd; ++NewParm) {
5536      if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
5537                                      Kind, TemplateArgLoc))
5538        return false;
5539    }
5540  }
5541
5542  // Make sure we exhausted all of the arguments.
5543  if (NewParm != NewParmEnd) {
5544    if (Complain)
5545      DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5546                                                 TemplateArgLoc);
5547
5548    return false;
5549  }
5550
5551  return true;
5552}
5553
5554/// \brief Check whether a template can be declared within this scope.
5555///
5556/// If the template declaration is valid in this scope, returns
5557/// false. Otherwise, issues a diagnostic and returns true.
5558bool
5559Sema::CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams) {
5560  if (!S)
5561    return false;
5562
5563  // Find the nearest enclosing declaration scope.
5564  while ((S->getFlags() & Scope::DeclScope) == 0 ||
5565         (S->getFlags() & Scope::TemplateParamScope) != 0)
5566    S = S->getParent();
5567
5568  // C++ [temp]p4:
5569  //   A template [...] shall not have C linkage.
5570  DeclContext *Ctx = S->getEntity();
5571  if (Ctx && Ctx->isExternCContext())
5572    return Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage)
5573             << TemplateParams->getSourceRange();
5574
5575  while (Ctx && isa<LinkageSpecDecl>(Ctx))
5576    Ctx = Ctx->getParent();
5577
5578  // C++ [temp]p2:
5579  //   A template-declaration can appear only as a namespace scope or
5580  //   class scope declaration.
5581  if (Ctx) {
5582    if (Ctx->isFileContext())
5583      return false;
5584    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Ctx)) {
5585      // C++ [temp.mem]p2:
5586      //   A local class shall not have member templates.
5587      if (RD->isLocalClass())
5588        return Diag(TemplateParams->getTemplateLoc(),
5589                    diag::err_template_inside_local_class)
5590          << TemplateParams->getSourceRange();
5591      else
5592        return false;
5593    }
5594  }
5595
5596  return Diag(TemplateParams->getTemplateLoc(),
5597              diag::err_template_outside_namespace_or_class_scope)
5598    << TemplateParams->getSourceRange();
5599}
5600
5601/// \brief Determine what kind of template specialization the given declaration
5602/// is.
5603static TemplateSpecializationKind getTemplateSpecializationKind(Decl *D) {
5604  if (!D)
5605    return TSK_Undeclared;
5606
5607  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D))
56