clang  7.0.0svn
SemaTemplate.cpp
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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"
20 #include "clang/AST/TypeVisitor.h"
21 #include "clang/Basic/Builtins.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
26 #include "clang/Sema/Lookup.h"
28 #include "clang/Sema/Scope.h"
30 #include "clang/Sema/Template.h"
32 #include "llvm/ADT/SmallBitVector.h"
33 #include "llvm/ADT/SmallString.h"
34 #include "llvm/ADT/StringExtras.h"
35 
36 #include <iterator>
37 using namespace clang;
38 using namespace sema;
39 
40 // Exported for use by Parser.
43  unsigned N) {
44  if (!N) return SourceRange();
45  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
46 }
47 
48 namespace clang {
49 /// \brief [temp.constr.decl]p2: A template's associated constraints are
50 /// defined as a single constraint-expression derived from the introduced
51 /// constraint-expressions [ ... ].
52 ///
53 /// \param Params The template parameter list and optional requires-clause.
54 ///
55 /// \param FD The underlying templated function declaration for a function
56 /// template.
58  FunctionDecl *FD);
59 }
60 
62  FunctionDecl *FD) {
63  // FIXME: Concepts: collect additional introduced constraint-expressions
64  assert(!FD && "Cannot collect constraints from function declaration yet.");
65  return Params->getRequiresClause();
66 }
67 
68 /// \brief Determine whether the declaration found is acceptable as the name
69 /// of a template and, if so, return that template declaration. Otherwise,
70 /// returns NULL.
72  NamedDecl *Orig,
73  bool AllowFunctionTemplates) {
74  NamedDecl *D = Orig->getUnderlyingDecl();
75 
76  if (isa<TemplateDecl>(D)) {
77  if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
78  return nullptr;
79 
80  return Orig;
81  }
82 
83  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
84  // C++ [temp.local]p1:
85  // Like normal (non-template) classes, class templates have an
86  // injected-class-name (Clause 9). The injected-class-name
87  // can be used with or without a template-argument-list. When
88  // it is used without a template-argument-list, it is
89  // equivalent to the injected-class-name followed by the
90  // template-parameters of the class template enclosed in
91  // <>. When it is used with a template-argument-list, it
92  // refers to the specified class template specialization,
93  // which could be the current specialization or another
94  // specialization.
95  if (Record->isInjectedClassName()) {
96  Record = cast<CXXRecordDecl>(Record->getDeclContext());
97  if (Record->getDescribedClassTemplate())
98  return Record->getDescribedClassTemplate();
99 
101  = dyn_cast<ClassTemplateSpecializationDecl>(Record))
102  return Spec->getSpecializedTemplate();
103  }
104 
105  return nullptr;
106  }
107 
108  return nullptr;
109 }
110 
112  bool AllowFunctionTemplates) {
113  // The set of class templates we've already seen.
114  llvm::SmallPtrSet<ClassTemplateDecl *, 8> ClassTemplates;
115  LookupResult::Filter filter = R.makeFilter();
116  while (filter.hasNext()) {
117  NamedDecl *Orig = filter.next();
118  NamedDecl *Repl = isAcceptableTemplateName(Context, Orig,
119  AllowFunctionTemplates);
120  if (!Repl)
121  filter.erase();
122  else if (Repl != Orig) {
123 
124  // C++ [temp.local]p3:
125  // A lookup that finds an injected-class-name (10.2) can result in an
126  // ambiguity in certain cases (for example, if it is found in more than
127  // one base class). If all of the injected-class-names that are found
128  // refer to specializations of the same class template, and if the name
129  // is used as a template-name, the reference refers to the class
130  // template itself and not a specialization thereof, and is not
131  // ambiguous.
132  if (ClassTemplateDecl *ClassTmpl = dyn_cast<ClassTemplateDecl>(Repl))
133  if (!ClassTemplates.insert(ClassTmpl).second) {
134  filter.erase();
135  continue;
136  }
137 
138  // FIXME: we promote access to public here as a workaround to
139  // the fact that LookupResult doesn't let us remember that we
140  // found this template through a particular injected class name,
141  // which means we end up doing nasty things to the invariants.
142  // Pretending that access is public is *much* safer.
143  filter.replace(Repl, AS_public);
144  }
145  }
146  filter.done();
147 }
148 
150  bool AllowFunctionTemplates) {
151  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I)
152  if (isAcceptableTemplateName(Context, *I, AllowFunctionTemplates))
153  return true;
154 
155  return false;
156 }
157 
159  CXXScopeSpec &SS,
160  bool hasTemplateKeyword,
161  UnqualifiedId &Name,
162  ParsedType ObjectTypePtr,
163  bool EnteringContext,
164  TemplateTy &TemplateResult,
165  bool &MemberOfUnknownSpecialization) {
166  assert(getLangOpts().CPlusPlus && "No template names in C!");
167 
168  DeclarationName TName;
169  MemberOfUnknownSpecialization = false;
170 
171  switch (Name.getKind()) {
173  TName = DeclarationName(Name.Identifier);
174  break;
175 
177  TName = Context.DeclarationNames.getCXXOperatorName(
179  break;
180 
183  break;
184 
185  default:
186  return TNK_Non_template;
187  }
188 
189  QualType ObjectType = ObjectTypePtr.get();
190 
191  LookupResult R(*this, TName, Name.getLocStart(), LookupOrdinaryName);
192  LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
193  MemberOfUnknownSpecialization);
194  if (R.empty()) return TNK_Non_template;
195  if (R.isAmbiguous()) {
196  // Suppress diagnostics; we'll redo this lookup later.
197  R.suppressDiagnostics();
198 
199  // FIXME: we might have ambiguous templates, in which case we
200  // should at least parse them properly!
201  return TNK_Non_template;
202  }
203 
204  TemplateName Template;
205  TemplateNameKind TemplateKind;
206 
207  unsigned ResultCount = R.end() - R.begin();
208  if (ResultCount > 1) {
209  // We assume that we'll preserve the qualifier from a function
210  // template name in other ways.
211  Template = Context.getOverloadedTemplateName(R.begin(), R.end());
212  TemplateKind = TNK_Function_template;
213 
214  // We'll do this lookup again later.
215  R.suppressDiagnostics();
216  } else {
217  TemplateDecl *TD = cast<TemplateDecl>((*R.begin())->getUnderlyingDecl());
218 
219  if (SS.isSet() && !SS.isInvalid()) {
220  NestedNameSpecifier *Qualifier = SS.getScopeRep();
221  Template = Context.getQualifiedTemplateName(Qualifier,
222  hasTemplateKeyword, TD);
223  } else {
224  Template = TemplateName(TD);
225  }
226 
227  if (isa<FunctionTemplateDecl>(TD)) {
228  TemplateKind = TNK_Function_template;
229 
230  // We'll do this lookup again later.
231  R.suppressDiagnostics();
232  } else {
233  assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
234  isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
235  isa<BuiltinTemplateDecl>(TD));
236  TemplateKind =
237  isa<VarTemplateDecl>(TD) ? TNK_Var_template : TNK_Type_template;
238  }
239  }
240 
241  TemplateResult = TemplateTy::make(Template);
242  return TemplateKind;
243 }
244 
246  SourceLocation NameLoc,
247  ParsedTemplateTy *Template) {
248  CXXScopeSpec SS;
249  bool MemberOfUnknownSpecialization = false;
250 
251  // We could use redeclaration lookup here, but we don't need to: the
252  // syntactic form of a deduction guide is enough to identify it even
253  // if we can't look up the template name at all.
254  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
255  LookupTemplateName(R, S, SS, /*ObjectType*/QualType(),
256  /*EnteringContext*/false, MemberOfUnknownSpecialization);
257 
258  if (R.empty()) return false;
259  if (R.isAmbiguous()) {
260  // FIXME: Diagnose an ambiguity if we find at least one template.
262  return false;
263  }
264 
265  // We only treat template-names that name type templates as valid deduction
266  // guide names.
268  if (!TD || !getAsTypeTemplateDecl(TD))
269  return false;
270 
271  if (Template)
272  *Template = TemplateTy::make(TemplateName(TD));
273  return true;
274 }
275 
277  SourceLocation IILoc,
278  Scope *S,
279  const CXXScopeSpec *SS,
280  TemplateTy &SuggestedTemplate,
281  TemplateNameKind &SuggestedKind) {
282  // We can't recover unless there's a dependent scope specifier preceding the
283  // template name.
284  // FIXME: Typo correction?
285  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
286  computeDeclContext(*SS))
287  return false;
288 
289  // The code is missing a 'template' keyword prior to the dependent template
290  // name.
292  Diag(IILoc, diag::err_template_kw_missing)
293  << Qualifier << II.getName()
294  << FixItHint::CreateInsertion(IILoc, "template ");
295  SuggestedTemplate
296  = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
297  SuggestedKind = TNK_Dependent_template_name;
298  return true;
299 }
300 
302  Scope *S, CXXScopeSpec &SS,
303  QualType ObjectType,
304  bool EnteringContext,
305  bool &MemberOfUnknownSpecialization) {
306  // Determine where to perform name lookup
307  MemberOfUnknownSpecialization = false;
308  DeclContext *LookupCtx = nullptr;
309  bool isDependent = false;
310  if (!ObjectType.isNull()) {
311  // This nested-name-specifier occurs in a member access expression, e.g.,
312  // x->B::f, and we are looking into the type of the object.
313  assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
314  LookupCtx = computeDeclContext(ObjectType);
315  isDependent = ObjectType->isDependentType();
316  assert((isDependent || !ObjectType->isIncompleteType() ||
317  ObjectType->castAs<TagType>()->isBeingDefined()) &&
318  "Caller should have completed object type");
319 
320  // Template names cannot appear inside an Objective-C class or object type.
321  if (ObjectType->isObjCObjectOrInterfaceType()) {
322  Found.clear();
323  return;
324  }
325  } else if (SS.isSet()) {
326  // This nested-name-specifier occurs after another nested-name-specifier,
327  // so long into the context associated with the prior nested-name-specifier.
328  LookupCtx = computeDeclContext(SS, EnteringContext);
329  isDependent = isDependentScopeSpecifier(SS);
330 
331  // The declaration context must be complete.
332  if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
333  return;
334  }
335 
336  bool ObjectTypeSearchedInScope = false;
337  bool AllowFunctionTemplatesInLookup = true;
338  if (LookupCtx) {
339  // Perform "qualified" name lookup into the declaration context we
340  // computed, which is either the type of the base of a member access
341  // expression or the declaration context associated with a prior
342  // nested-name-specifier.
343  LookupQualifiedName(Found, LookupCtx);
344  if (!ObjectType.isNull() && Found.empty()) {
345  // C++ [basic.lookup.classref]p1:
346  // In a class member access expression (5.2.5), if the . or -> token is
347  // immediately followed by an identifier followed by a <, the
348  // identifier must be looked up to determine whether the < is the
349  // beginning of a template argument list (14.2) or a less-than operator.
350  // The identifier is first looked up in the class of the object
351  // expression. If the identifier is not found, it is then looked up in
352  // the context of the entire postfix-expression and shall name a class
353  // or function template.
354  if (S) LookupName(Found, S);
355  ObjectTypeSearchedInScope = true;
356  AllowFunctionTemplatesInLookup = false;
357  }
358  } else if (isDependent && (!S || ObjectType.isNull())) {
359  // We cannot look into a dependent object type or nested nme
360  // specifier.
361  MemberOfUnknownSpecialization = true;
362  return;
363  } else {
364  // Perform unqualified name lookup in the current scope.
365  LookupName(Found, S);
366 
367  if (!ObjectType.isNull())
368  AllowFunctionTemplatesInLookup = false;
369  }
370 
371  if (Found.empty() && !isDependent) {
372  // If we did not find any names, attempt to correct any typos.
373  DeclarationName Name = Found.getLookupName();
374  Found.clear();
375  // Simple filter callback that, for keywords, only accepts the C++ *_cast
376  auto FilterCCC = llvm::make_unique<CorrectionCandidateCallback>();
377  FilterCCC->WantTypeSpecifiers = false;
378  FilterCCC->WantExpressionKeywords = false;
379  FilterCCC->WantRemainingKeywords = false;
380  FilterCCC->WantCXXNamedCasts = true;
381  if (TypoCorrection Corrected = CorrectTypo(
382  Found.getLookupNameInfo(), Found.getLookupKind(), S, &SS,
383  std::move(FilterCCC), CTK_ErrorRecovery, LookupCtx)) {
384  Found.setLookupName(Corrected.getCorrection());
385  if (auto *ND = Corrected.getFoundDecl())
386  Found.addDecl(ND);
387  FilterAcceptableTemplateNames(Found);
388  if (!Found.empty()) {
389  if (LookupCtx) {
390  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
391  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
392  Name.getAsString() == CorrectedStr;
393  diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
394  << Name << LookupCtx << DroppedSpecifier
395  << SS.getRange());
396  } else {
397  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
398  }
399  }
400  } else {
401  Found.setLookupName(Name);
402  }
403  }
404 
405  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
406  if (Found.empty()) {
407  if (isDependent)
408  MemberOfUnknownSpecialization = true;
409  return;
410  }
411 
412  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
413  !getLangOpts().CPlusPlus11) {
414  // C++03 [basic.lookup.classref]p1:
415  // [...] If the lookup in the class of the object expression finds a
416  // template, the name is also looked up in the context of the entire
417  // postfix-expression and [...]
418  //
419  // Note: C++11 does not perform this second lookup.
420  LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
421  LookupOrdinaryName);
422  LookupName(FoundOuter, S);
423  FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
424 
425  if (FoundOuter.empty()) {
426  // - if the name is not found, the name found in the class of the
427  // object expression is used, otherwise
428  } else if (!FoundOuter.getAsSingle<ClassTemplateDecl>() ||
429  FoundOuter.isAmbiguous()) {
430  // - if the name is found in the context of the entire
431  // postfix-expression and does not name a class template, the name
432  // found in the class of the object expression is used, otherwise
433  FoundOuter.clear();
434  } else if (!Found.isSuppressingDiagnostics()) {
435  // - if the name found is a class template, it must refer to the same
436  // entity as the one found in the class of the object expression,
437  // otherwise the program is ill-formed.
438  if (!Found.isSingleResult() ||
439  Found.getFoundDecl()->getCanonicalDecl()
440  != FoundOuter.getFoundDecl()->getCanonicalDecl()) {
441  Diag(Found.getNameLoc(),
442  diag::ext_nested_name_member_ref_lookup_ambiguous)
443  << Found.getLookupName()
444  << ObjectType;
446  diag::note_ambig_member_ref_object_type)
447  << ObjectType;
448  Diag(FoundOuter.getFoundDecl()->getLocation(),
449  diag::note_ambig_member_ref_scope);
450 
451  // Recover by taking the template that we found in the object
452  // expression's type.
453  }
454  }
455  }
456 }
457 
459  SourceLocation Less,
460  SourceLocation Greater) {
461  if (TemplateName.isInvalid())
462  return;
463 
464  DeclarationNameInfo NameInfo;
465  CXXScopeSpec SS;
466  LookupNameKind LookupKind;
467 
468  DeclContext *LookupCtx = nullptr;
469  NamedDecl *Found = nullptr;
470 
471  // Figure out what name we looked up.
472  if (auto *ME = dyn_cast<MemberExpr>(TemplateName.get())) {
473  NameInfo = ME->getMemberNameInfo();
474  SS.Adopt(ME->getQualifierLoc());
475  LookupKind = LookupMemberName;
476  LookupCtx = ME->getBase()->getType()->getAsCXXRecordDecl();
477  Found = ME->getMemberDecl();
478  } else {
479  auto *DRE = cast<DeclRefExpr>(TemplateName.get());
480  NameInfo = DRE->getNameInfo();
481  SS.Adopt(DRE->getQualifierLoc());
482  LookupKind = LookupOrdinaryName;
483  Found = DRE->getFoundDecl();
484  }
485 
486  // Try to correct the name by looking for templates and C++ named casts.
487  struct TemplateCandidateFilter : CorrectionCandidateCallback {
488  TemplateCandidateFilter() {
489  WantTypeSpecifiers = false;
490  WantExpressionKeywords = false;
491  WantRemainingKeywords = false;
492  WantCXXNamedCasts = true;
493  };
494  bool ValidateCandidate(const TypoCorrection &Candidate) override {
495  if (auto *ND = Candidate.getCorrectionDecl())
496  return isAcceptableTemplateName(ND->getASTContext(), ND, true);
497  return Candidate.isKeyword();
498  }
499  };
500 
501  DeclarationName Name = NameInfo.getName();
502  if (TypoCorrection Corrected =
503  CorrectTypo(NameInfo, LookupKind, S, &SS,
504  llvm::make_unique<TemplateCandidateFilter>(),
505  CTK_ErrorRecovery, LookupCtx)) {
506  auto *ND = Corrected.getFoundDecl();
507  if (ND)
508  ND = isAcceptableTemplateName(Context, ND,
509  /*AllowFunctionTemplates*/ true);
510  if (ND || Corrected.isKeyword()) {
511  if (LookupCtx) {
512  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
513  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
514  Name.getAsString() == CorrectedStr;
515  diagnoseTypo(Corrected,
516  PDiag(diag::err_non_template_in_member_template_id_suggest)
517  << Name << LookupCtx << DroppedSpecifier
518  << SS.getRange(), false);
519  } else {
520  diagnoseTypo(Corrected,
521  PDiag(diag::err_non_template_in_template_id_suggest)
522  << Name, false);
523  }
524  if (Found)
525  Diag(Found->getLocation(),
526  diag::note_non_template_in_template_id_found);
527  return;
528  }
529  }
530 
531  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
532  << Name << SourceRange(Less, Greater);
533  if (Found)
534  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
535 }
536 
537 /// ActOnDependentIdExpression - Handle a dependent id-expression that
538 /// was just parsed. This is only possible with an explicit scope
539 /// specifier naming a dependent type.
542  SourceLocation TemplateKWLoc,
543  const DeclarationNameInfo &NameInfo,
544  bool isAddressOfOperand,
545  const TemplateArgumentListInfo *TemplateArgs) {
546  DeclContext *DC = getFunctionLevelDeclContext();
547 
548  // C++11 [expr.prim.general]p12:
549  // An id-expression that denotes a non-static data member or non-static
550  // member function of a class can only be used:
551  // (...)
552  // - if that id-expression denotes a non-static data member and it
553  // appears in an unevaluated operand.
554  //
555  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
556  // CXXDependentScopeMemberExpr. The former can instantiate to either
557  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
558  // always a MemberExpr.
559  bool MightBeCxx11UnevalField =
560  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
561 
562  // Check if the nested name specifier is an enum type.
563  bool IsEnum = false;
564  if (NestedNameSpecifier *NNS = SS.getScopeRep())
565  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
566 
567  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
568  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
569  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
570 
571  // Since the 'this' expression is synthesized, we don't need to
572  // perform the double-lookup check.
573  NamedDecl *FirstQualifierInScope = nullptr;
574 
576  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
577  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
578  FirstQualifierInScope, NameInfo, TemplateArgs);
579  }
580 
581  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
582 }
583 
586  SourceLocation TemplateKWLoc,
587  const DeclarationNameInfo &NameInfo,
588  const TemplateArgumentListInfo *TemplateArgs) {
590  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
591  TemplateArgs);
592 }
593 
594 
595 /// Determine whether we would be unable to instantiate this template (because
596 /// it either has no definition, or is in the process of being instantiated).
598  NamedDecl *Instantiation,
599  bool InstantiatedFromMember,
600  const NamedDecl *Pattern,
601  const NamedDecl *PatternDef,
603  bool Complain /*= true*/) {
604  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
605  isa<VarDecl>(Instantiation));
606 
607  bool IsEntityBeingDefined = false;
608  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
609  IsEntityBeingDefined = TD->isBeingDefined();
610 
611  if (PatternDef && !IsEntityBeingDefined) {
612  NamedDecl *SuggestedDef = nullptr;
613  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
614  /*OnlyNeedComplete*/false)) {
615  // If we're allowed to diagnose this and recover, do so.
616  bool Recover = Complain && !isSFINAEContext();
617  if (Complain)
618  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
620  return !Recover;
621  }
622  return false;
623  }
624 
625  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
626  return true;
627 
629  QualType InstantiationTy;
630  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
631  InstantiationTy = Context.getTypeDeclType(TD);
632  if (PatternDef) {
633  Diag(PointOfInstantiation,
634  diag::err_template_instantiate_within_definition)
635  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
636  << InstantiationTy;
637  // Not much point in noting the template declaration here, since
638  // we're lexically inside it.
639  Instantiation->setInvalidDecl();
640  } else if (InstantiatedFromMember) {
641  if (isa<FunctionDecl>(Instantiation)) {
642  Diag(PointOfInstantiation,
643  diag::err_explicit_instantiation_undefined_member)
644  << /*member function*/ 1 << Instantiation->getDeclName()
645  << Instantiation->getDeclContext();
646  Note = diag::note_explicit_instantiation_here;
647  } else {
648  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
649  Diag(PointOfInstantiation,
650  diag::err_implicit_instantiate_member_undefined)
651  << InstantiationTy;
652  Note = diag::note_member_declared_at;
653  }
654  } else {
655  if (isa<FunctionDecl>(Instantiation)) {
656  Diag(PointOfInstantiation,
657  diag::err_explicit_instantiation_undefined_func_template)
658  << Pattern;
659  Note = diag::note_explicit_instantiation_here;
660  } else if (isa<TagDecl>(Instantiation)) {
661  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
662  << (TSK != TSK_ImplicitInstantiation)
663  << InstantiationTy;
664  Note = diag::note_template_decl_here;
665  } else {
666  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
667  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
668  Diag(PointOfInstantiation,
669  diag::err_explicit_instantiation_undefined_var_template)
670  << Instantiation;
671  Instantiation->setInvalidDecl();
672  } else
673  Diag(PointOfInstantiation,
674  diag::err_explicit_instantiation_undefined_member)
675  << /*static data member*/ 2 << Instantiation->getDeclName()
676  << Instantiation->getDeclContext();
677  Note = diag::note_explicit_instantiation_here;
678  }
679  }
680  if (Note) // Diagnostics were emitted.
681  Diag(Pattern->getLocation(), Note.getValue());
682 
683  // In general, Instantiation isn't marked invalid to get more than one
684  // error for multiple undefined instantiations. But the code that does
685  // explicit declaration -> explicit definition conversion can't handle
686  // invalid declarations, so mark as invalid in that case.
688  Instantiation->setInvalidDecl();
689  return true;
690 }
691 
692 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
693 /// that the template parameter 'PrevDecl' is being shadowed by a new
694 /// declaration at location Loc. Returns true to indicate that this is
695 /// an error, and false otherwise.
697  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
698 
699  // Microsoft Visual C++ permits template parameters to be shadowed.
700  if (getLangOpts().MicrosoftExt)
701  return;
702 
703  // C++ [temp.local]p4:
704  // A template-parameter shall not be redeclared within its
705  // scope (including nested scopes).
706  Diag(Loc, diag::err_template_param_shadow)
707  << cast<NamedDecl>(PrevDecl)->getDeclName();
708  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
709 }
710 
711 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
712 /// the parameter D to reference the templated declaration and return a pointer
713 /// to the template declaration. Otherwise, do nothing to D and return null.
715  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
716  D = Temp->getTemplatedDecl();
717  return Temp;
718  }
719  return nullptr;
720 }
721 
723  SourceLocation EllipsisLoc) const {
724  assert(Kind == Template &&
725  "Only template template arguments can be pack expansions here");
726  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
727  "Template template argument pack expansion without packs");
728  ParsedTemplateArgument Result(*this);
729  Result.EllipsisLoc = EllipsisLoc;
730  return Result;
731 }
732 
734  const ParsedTemplateArgument &Arg) {
735 
736  switch (Arg.getKind()) {
738  TypeSourceInfo *DI;
739  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
740  if (!DI)
741  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
742  return TemplateArgumentLoc(TemplateArgument(T), DI);
743  }
744 
746  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
748  }
749 
751  TemplateName Template = Arg.getAsTemplate().get();
752  TemplateArgument TArg;
753  if (Arg.getEllipsisLoc().isValid())
754  TArg = TemplateArgument(Template, Optional<unsigned int>());
755  else
756  TArg = Template;
757  return TemplateArgumentLoc(TArg,
759  SemaRef.Context),
760  Arg.getLocation(),
761  Arg.getEllipsisLoc());
762  }
763  }
764 
765  llvm_unreachable("Unhandled parsed template argument");
766 }
767 
768 /// \brief Translates template arguments as provided by the parser
769 /// into template arguments used by semantic analysis.
771  TemplateArgumentListInfo &TemplateArgs) {
772  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
773  TemplateArgs.addArgument(translateTemplateArgument(*this,
774  TemplateArgsIn[I]));
775 }
776 
778  SourceLocation Loc,
779  IdentifierInfo *Name) {
780  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
782  if (PrevDecl && PrevDecl->isTemplateParameter())
783  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
784 }
785 
786 /// Convert a parsed type into a parsed template argument. This is mostly
787 /// trivial, except that we may have parsed a C++17 deduced class template
788 /// specialization type, in which case we should form a template template
789 /// argument instead of a type template argument.
791  TypeSourceInfo *TInfo;
792  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
793  if (T.isNull())
794  return ParsedTemplateArgument();
795  assert(TInfo && "template argument with no location");
796 
797  // If we might have formed a deduced template specialization type, convert
798  // it to a template template argument.
799  if (getLangOpts().CPlusPlus17) {
800  TypeLoc TL = TInfo->getTypeLoc();
801  SourceLocation EllipsisLoc;
802  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
803  EllipsisLoc = PET.getEllipsisLoc();
804  TL = PET.getPatternLoc();
805  }
806 
807  CXXScopeSpec SS;
808  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
809  SS.Adopt(ET.getQualifierLoc());
810  TL = ET.getNamedTypeLoc();
811  }
812 
813  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
814  TemplateName Name = DTST.getTypePtr()->getTemplateName();
815  if (SS.isSet())
816  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
817  /*HasTemplateKeyword*/ false,
818  Name.getAsTemplateDecl());
819  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
820  DTST.getTemplateNameLoc());
821  if (EllipsisLoc.isValid())
822  Result = Result.getTemplatePackExpansion(EllipsisLoc);
823  return Result;
824  }
825  }
826 
827  // This is a normal type template argument. Note, if the type template
828  // argument is an injected-class-name for a template, it has a dual nature
829  // and can be used as either a type or a template. We handle that in
830  // convertTypeTemplateArgumentToTemplate.
832  ParsedType.get().getAsOpaquePtr(),
833  TInfo->getTypeLoc().getLocStart());
834 }
835 
836 /// ActOnTypeParameter - Called when a C++ template type parameter
837 /// (e.g., "typename T") has been parsed. Typename specifies whether
838 /// the keyword "typename" was used to declare the type parameter
839 /// (otherwise, "class" was used), and KeyLoc is the location of the
840 /// "class" or "typename" keyword. ParamName is the name of the
841 /// parameter (NULL indicates an unnamed template parameter) and
842 /// ParamNameLoc is the location of the parameter name (if any).
843 /// If the type parameter has a default argument, it will be added
844 /// later via ActOnTypeParameterDefault.
846  SourceLocation EllipsisLoc,
847  SourceLocation KeyLoc,
848  IdentifierInfo *ParamName,
849  SourceLocation ParamNameLoc,
850  unsigned Depth, unsigned Position,
851  SourceLocation EqualLoc,
852  ParsedType DefaultArg) {
853  assert(S->isTemplateParamScope() &&
854  "Template type parameter not in template parameter scope!");
855 
856  SourceLocation Loc = ParamNameLoc;
857  if (!ParamName)
858  Loc = KeyLoc;
859 
860  bool IsParameterPack = EllipsisLoc.isValid();
861  TemplateTypeParmDecl *Param
863  KeyLoc, Loc, Depth, Position, ParamName,
864  Typename, IsParameterPack);
865  Param->setAccess(AS_public);
866 
867  if (ParamName) {
868  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
869 
870  // Add the template parameter into the current scope.
871  S->AddDecl(Param);
872  IdResolver.AddDecl(Param);
873  }
874 
875  // C++0x [temp.param]p9:
876  // A default template-argument may be specified for any kind of
877  // template-parameter that is not a template parameter pack.
878  if (DefaultArg && IsParameterPack) {
879  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
880  DefaultArg = nullptr;
881  }
882 
883  // Handle the default argument, if provided.
884  if (DefaultArg) {
885  TypeSourceInfo *DefaultTInfo;
886  GetTypeFromParser(DefaultArg, &DefaultTInfo);
887 
888  assert(DefaultTInfo && "expected source information for type");
889 
890  // Check for unexpanded parameter packs.
891  if (DiagnoseUnexpandedParameterPack(Loc, DefaultTInfo,
892  UPPC_DefaultArgument))
893  return Param;
894 
895  // Check the template argument itself.
896  if (CheckTemplateArgument(Param, DefaultTInfo)) {
897  Param->setInvalidDecl();
898  return Param;
899  }
900 
901  Param->setDefaultArgument(DefaultTInfo);
902  }
903 
904  return Param;
905 }
906 
907 /// \brief Check that the type of a non-type template parameter is
908 /// well-formed.
909 ///
910 /// \returns the (possibly-promoted) parameter type if valid;
911 /// otherwise, produces a diagnostic and returns a NULL type.
913  SourceLocation Loc) {
914  if (TSI->getType()->isUndeducedType()) {
915  // C++1z [temp.dep.expr]p3:
916  // An id-expression is type-dependent if it contains
917  // - an identifier associated by name lookup with a non-type
918  // template-parameter declared with a type that contains a
919  // placeholder type (7.1.7.4),
920  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
921  }
922 
923  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
924 }
925 
927  SourceLocation Loc) {
928  // We don't allow variably-modified types as the type of non-type template
929  // parameters.
930  if (T->isVariablyModifiedType()) {
931  Diag(Loc, diag::err_variably_modified_nontype_template_param)
932  << T;
933  return QualType();
934  }
935 
936  // C++ [temp.param]p4:
937  //
938  // A non-type template-parameter shall have one of the following
939  // (optionally cv-qualified) types:
940  //
941  // -- integral or enumeration type,
942  if (T->isIntegralOrEnumerationType() ||
943  // -- pointer to object or pointer to function,
944  T->isPointerType() ||
945  // -- reference to object or reference to function,
946  T->isReferenceType() ||
947  // -- pointer to member,
948  T->isMemberPointerType() ||
949  // -- std::nullptr_t.
950  T->isNullPtrType() ||
951  // If T is a dependent type, we can't do the check now, so we
952  // assume that it is well-formed.
953  T->isDependentType() ||
954  // Allow use of auto in template parameter declarations.
955  T->isUndeducedType()) {
956  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
957  // are ignored when determining its type.
958  return T.getUnqualifiedType();
959  }
960 
961  // C++ [temp.param]p8:
962  //
963  // A non-type template-parameter of type "array of T" or
964  // "function returning T" is adjusted to be of type "pointer to
965  // T" or "pointer to function returning T", respectively.
966  else if (T->isArrayType() || T->isFunctionType())
967  return Context.getDecayedType(T);
968 
969  Diag(Loc, diag::err_template_nontype_parm_bad_type)
970  << T;
971 
972  return QualType();
973 }
974 
976  unsigned Depth,
977  unsigned Position,
978  SourceLocation EqualLoc,
979  Expr *Default) {
980  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
981 
982  // Check that we have valid decl-specifiers specified.
983  auto CheckValidDeclSpecifiers = [this, &D] {
984  // C++ [temp.param]
985  // p1
986  // template-parameter:
987  // ...
988  // parameter-declaration
989  // p2
990  // ... A storage class shall not be specified in a template-parameter
991  // declaration.
992  // [dcl.typedef]p1:
993  // The typedef specifier [...] shall not be used in the decl-specifier-seq
994  // of a parameter-declaration
995  const DeclSpec &DS = D.getDeclSpec();
996  auto EmitDiag = [this](SourceLocation Loc) {
997  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
998  << FixItHint::CreateRemoval(Loc);
999  };
1001  EmitDiag(DS.getStorageClassSpecLoc());
1002 
1004  EmitDiag(DS.getThreadStorageClassSpecLoc());
1005 
1006  // [dcl.inline]p1:
1007  // The inline specifier can be applied only to the declaration or
1008  // definition of a variable or function.
1009 
1010  if (DS.isInlineSpecified())
1011  EmitDiag(DS.getInlineSpecLoc());
1012 
1013  // [dcl.constexpr]p1:
1014  // The constexpr specifier shall be applied only to the definition of a
1015  // variable or variable template or the declaration of a function or
1016  // function template.
1017 
1018  if (DS.isConstexprSpecified())
1019  EmitDiag(DS.getConstexprSpecLoc());
1020 
1021  // [dcl.fct.spec]p1:
1022  // Function-specifiers can be used only in function declarations.
1023 
1024  if (DS.isVirtualSpecified())
1025  EmitDiag(DS.getVirtualSpecLoc());
1026 
1027  if (DS.isExplicitSpecified())
1028  EmitDiag(DS.getExplicitSpecLoc());
1029 
1030  if (DS.isNoreturnSpecified())
1031  EmitDiag(DS.getNoreturnSpecLoc());
1032  };
1033 
1034  CheckValidDeclSpecifiers();
1035 
1036  if (TInfo->getType()->isUndeducedType()) {
1037  Diag(D.getIdentifierLoc(),
1038  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1039  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1040  }
1041 
1042  assert(S->isTemplateParamScope() &&
1043  "Non-type template parameter not in template parameter scope!");
1044  bool Invalid = false;
1045 
1046  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1047  if (T.isNull()) {
1048  T = Context.IntTy; // Recover with an 'int' type.
1049  Invalid = true;
1050  }
1051 
1052  IdentifierInfo *ParamName = D.getIdentifier();
1053  bool IsParameterPack = D.hasEllipsis();
1056  D.getLocStart(),
1057  D.getIdentifierLoc(),
1058  Depth, Position, ParamName, T,
1059  IsParameterPack, TInfo);
1060  Param->setAccess(AS_public);
1061 
1062  if (Invalid)
1063  Param->setInvalidDecl();
1064 
1065  if (ParamName) {
1067  ParamName);
1068 
1069  // Add the template parameter into the current scope.
1070  S->AddDecl(Param);
1071  IdResolver.AddDecl(Param);
1072  }
1073 
1074  // C++0x [temp.param]p9:
1075  // A default template-argument may be specified for any kind of
1076  // template-parameter that is not a template parameter pack.
1077  if (Default && IsParameterPack) {
1078  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1079  Default = nullptr;
1080  }
1081 
1082  // Check the well-formedness of the default template argument, if provided.
1083  if (Default) {
1084  // Check for unexpanded parameter packs.
1085  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1086  return Param;
1087 
1088  TemplateArgument Converted;
1089  ExprResult DefaultRes =
1090  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1091  if (DefaultRes.isInvalid()) {
1092  Param->setInvalidDecl();
1093  return Param;
1094  }
1095  Default = DefaultRes.get();
1096 
1097  Param->setDefaultArgument(Default);
1098  }
1099 
1100  return Param;
1101 }
1102 
1103 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1104 /// parameter (e.g. T in template <template <typename> class T> class array)
1105 /// has been parsed. S is the current scope.
1107  SourceLocation TmpLoc,
1108  TemplateParameterList *Params,
1109  SourceLocation EllipsisLoc,
1110  IdentifierInfo *Name,
1111  SourceLocation NameLoc,
1112  unsigned Depth,
1113  unsigned Position,
1114  SourceLocation EqualLoc,
1115  ParsedTemplateArgument Default) {
1116  assert(S->isTemplateParamScope() &&
1117  "Template template parameter not in template parameter scope!");
1118 
1119  // Construct the parameter object.
1120  bool IsParameterPack = EllipsisLoc.isValid();
1121  TemplateTemplateParmDecl *Param =
1123  NameLoc.isInvalid()? TmpLoc : NameLoc,
1124  Depth, Position, IsParameterPack,
1125  Name, Params);
1126  Param->setAccess(AS_public);
1127 
1128  // If the template template parameter has a name, then link the identifier
1129  // into the scope and lookup mechanisms.
1130  if (Name) {
1131  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1132 
1133  S->AddDecl(Param);
1134  IdResolver.AddDecl(Param);
1135  }
1136 
1137  if (Params->size() == 0) {
1138  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1139  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1140  Param->setInvalidDecl();
1141  }
1142 
1143  // C++0x [temp.param]p9:
1144  // A default template-argument may be specified for any kind of
1145  // template-parameter that is not a template parameter pack.
1146  if (IsParameterPack && !Default.isInvalid()) {
1147  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1148  Default = ParsedTemplateArgument();
1149  }
1150 
1151  if (!Default.isInvalid()) {
1152  // Check only that we have a template template argument. We don't want to
1153  // try to check well-formedness now, because our template template parameter
1154  // might have dependent types in its template parameters, which we wouldn't
1155  // be able to match now.
1156  //
1157  // If none of the template template parameter's template arguments mention
1158  // other template parameters, we could actually perform more checking here.
1159  // However, it isn't worth doing.
1160  TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
1161  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1162  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1163  << DefaultArg.getSourceRange();
1164  return Param;
1165  }
1166 
1167  // Check for unexpanded parameter packs.
1168  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1169  DefaultArg.getArgument().getAsTemplate(),
1170  UPPC_DefaultArgument))
1171  return Param;
1172 
1173  Param->setDefaultArgument(Context, DefaultArg);
1174  }
1175 
1176  return Param;
1177 }
1178 
1179 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1180 /// constrained by RequiresClause, that contains the template parameters in
1181 /// Params.
1184  SourceLocation ExportLoc,
1185  SourceLocation TemplateLoc,
1186  SourceLocation LAngleLoc,
1187  ArrayRef<NamedDecl *> Params,
1188  SourceLocation RAngleLoc,
1189  Expr *RequiresClause) {
1190  if (ExportLoc.isValid())
1191  Diag(ExportLoc, diag::warn_template_export_unsupported);
1192 
1194  Context, TemplateLoc, LAngleLoc,
1195  llvm::makeArrayRef(Params.data(), Params.size()),
1196  RAngleLoc, RequiresClause);
1197 }
1198 
1199 static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
1200  if (SS.isSet())
1202 }
1203 
1204 DeclResult
1205 Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
1206  SourceLocation KWLoc, CXXScopeSpec &SS,
1207  IdentifierInfo *Name, SourceLocation NameLoc,
1209  TemplateParameterList *TemplateParams,
1210  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1211  SourceLocation FriendLoc,
1212  unsigned NumOuterTemplateParamLists,
1213  TemplateParameterList** OuterTemplateParamLists,
1214  SkipBodyInfo *SkipBody) {
1215  assert(TemplateParams && TemplateParams->size() > 0 &&
1216  "No template parameters");
1217  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1218  bool Invalid = false;
1219 
1220  // Check that we can declare a template here.
1221  if (CheckTemplateDeclScope(S, TemplateParams))
1222  return true;
1223 
1225  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1226 
1227  // There is no such thing as an unnamed class template.
1228  if (!Name) {
1229  Diag(KWLoc, diag::err_template_unnamed_class);
1230  return true;
1231  }
1232 
1233  // Find any previous declaration with this name. For a friend with no
1234  // scope explicitly specified, we only look for tag declarations (per
1235  // C++11 [basic.lookup.elab]p2).
1236  DeclContext *SemanticContext;
1237  LookupResult Previous(*this, Name, NameLoc,
1238  (SS.isEmpty() && TUK == TUK_Friend)
1239  ? LookupTagName : LookupOrdinaryName,
1240  forRedeclarationInCurContext());
1241  if (SS.isNotEmpty() && !SS.isInvalid()) {
1242  SemanticContext = computeDeclContext(SS, true);
1243  if (!SemanticContext) {
1244  // FIXME: Horrible, horrible hack! We can't currently represent this
1245  // in the AST, and historically we have just ignored such friend
1246  // class templates, so don't complain here.
1247  Diag(NameLoc, TUK == TUK_Friend
1248  ? diag::warn_template_qualified_friend_ignored
1249  : diag::err_template_qualified_declarator_no_match)
1250  << SS.getScopeRep() << SS.getRange();
1251  return TUK != TUK_Friend;
1252  }
1253 
1254  if (RequireCompleteDeclContext(SS, SemanticContext))
1255  return true;
1256 
1257  // If we're adding a template to a dependent context, we may need to
1258  // rebuilding some of the types used within the template parameter list,
1259  // now that we know what the current instantiation is.
1260  if (SemanticContext->isDependentContext()) {
1261  ContextRAII SavedContext(*this, SemanticContext);
1262  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1263  Invalid = true;
1264  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1265  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1266 
1267  LookupQualifiedName(Previous, SemanticContext);
1268  } else {
1269  SemanticContext = CurContext;
1270 
1271  // C++14 [class.mem]p14:
1272  // If T is the name of a class, then each of the following shall have a
1273  // name different from T:
1274  // -- every member template of class T
1275  if (TUK != TUK_Friend &&
1276  DiagnoseClassNameShadow(SemanticContext,
1277  DeclarationNameInfo(Name, NameLoc)))
1278  return true;
1279 
1280  LookupName(Previous, S);
1281  }
1282 
1283  if (Previous.isAmbiguous())
1284  return true;
1285 
1286  NamedDecl *PrevDecl = nullptr;
1287  if (Previous.begin() != Previous.end())
1288  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1289 
1290  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1291  // Maybe we will complain about the shadowed template parameter.
1292  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1293  // Just pretend that we didn't see the previous declaration.
1294  PrevDecl = nullptr;
1295  }
1296 
1297  // If there is a previous declaration with the same name, check
1298  // whether this is a valid redeclaration.
1299  ClassTemplateDecl *PrevClassTemplate =
1300  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1301 
1302  // We may have found the injected-class-name of a class template,
1303  // class template partial specialization, or class template specialization.
1304  // In these cases, grab the template that is being defined or specialized.
1305  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1306  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1307  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1308  PrevClassTemplate
1309  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1310  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1311  PrevClassTemplate
1312  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1313  ->getSpecializedTemplate();
1314  }
1315  }
1316 
1317  if (TUK == TUK_Friend) {
1318  // C++ [namespace.memdef]p3:
1319  // [...] When looking for a prior declaration of a class or a function
1320  // declared as a friend, and when the name of the friend class or
1321  // function is neither a qualified name nor a template-id, scopes outside
1322  // the innermost enclosing namespace scope are not considered.
1323  if (!SS.isSet()) {
1324  DeclContext *OutermostContext = CurContext;
1325  while (!OutermostContext->isFileContext())
1326  OutermostContext = OutermostContext->getLookupParent();
1327 
1328  if (PrevDecl &&
1329  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1330  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1331  SemanticContext = PrevDecl->getDeclContext();
1332  } else {
1333  // Declarations in outer scopes don't matter. However, the outermost
1334  // context we computed is the semantic context for our new
1335  // declaration.
1336  PrevDecl = PrevClassTemplate = nullptr;
1337  SemanticContext = OutermostContext;
1338 
1339  // Check that the chosen semantic context doesn't already contain a
1340  // declaration of this name as a non-tag type.
1341  Previous.clear(LookupOrdinaryName);
1342  DeclContext *LookupContext = SemanticContext;
1343  while (LookupContext->isTransparentContext())
1344  LookupContext = LookupContext->getLookupParent();
1345  LookupQualifiedName(Previous, LookupContext);
1346 
1347  if (Previous.isAmbiguous())
1348  return true;
1349 
1350  if (Previous.begin() != Previous.end())
1351  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1352  }
1353  }
1354  } else if (PrevDecl &&
1355  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1356  S, SS.isValid()))
1357  PrevDecl = PrevClassTemplate = nullptr;
1358 
1359  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1360  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1361  if (SS.isEmpty() &&
1362  !(PrevClassTemplate &&
1363  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1364  SemanticContext->getRedeclContext()))) {
1365  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1366  Diag(Shadow->getTargetDecl()->getLocation(),
1367  diag::note_using_decl_target);
1368  Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1369  // Recover by ignoring the old declaration.
1370  PrevDecl = PrevClassTemplate = nullptr;
1371  }
1372  }
1373 
1374  // TODO Memory management; associated constraints are not always stored.
1375  Expr *const CurAC = formAssociatedConstraints(TemplateParams, nullptr);
1376 
1377  if (PrevClassTemplate) {
1378  // Ensure that the template parameter lists are compatible. Skip this check
1379  // for a friend in a dependent context: the template parameter list itself
1380  // could be dependent.
1381  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1382  !TemplateParameterListsAreEqual(TemplateParams,
1383  PrevClassTemplate->getTemplateParameters(),
1384  /*Complain=*/true,
1385  TPL_TemplateMatch))
1386  return true;
1387 
1388  // Check for matching associated constraints on redeclarations.
1389  const Expr *const PrevAC = PrevClassTemplate->getAssociatedConstraints();
1390  const bool RedeclACMismatch = [&] {
1391  if (!(CurAC || PrevAC))
1392  return false; // Nothing to check; no mismatch.
1393  if (CurAC && PrevAC) {
1394  llvm::FoldingSetNodeID CurACInfo, PrevACInfo;
1395  CurAC->Profile(CurACInfo, Context, /*Canonical=*/true);
1396  PrevAC->Profile(PrevACInfo, Context, /*Canonical=*/true);
1397  if (CurACInfo == PrevACInfo)
1398  return false; // All good; no mismatch.
1399  }
1400  return true;
1401  }();
1402 
1403  if (RedeclACMismatch) {
1404  Diag(CurAC ? CurAC->getLocStart() : NameLoc,
1405  diag::err_template_different_associated_constraints);
1406  Diag(PrevAC ? PrevAC->getLocStart() : PrevClassTemplate->getLocation(),
1407  diag::note_template_prev_declaration) << /*declaration*/0;
1408  return true;
1409  }
1410 
1411  // C++ [temp.class]p4:
1412  // In a redeclaration, partial specialization, explicit
1413  // specialization or explicit instantiation of a class template,
1414  // the class-key shall agree in kind with the original class
1415  // template declaration (7.1.5.3).
1416  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1417  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1418  TUK == TUK_Definition, KWLoc, Name)) {
1419  Diag(KWLoc, diag::err_use_with_wrong_tag)
1420  << Name
1421  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1422  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1423  Kind = PrevRecordDecl->getTagKind();
1424  }
1425 
1426  // Check for redefinition of this class template.
1427  if (TUK == TUK_Definition) {
1428  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1429  // If we have a prior definition that is not visible, treat this as
1430  // simply making that previous definition visible.
1431  NamedDecl *Hidden = nullptr;
1432  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1433  SkipBody->ShouldSkip = true;
1434  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1435  assert(Tmpl && "original definition of a class template is not a "
1436  "class template?");
1437  makeMergedDefinitionVisible(Hidden);
1438  makeMergedDefinitionVisible(Tmpl);
1439  return Def;
1440  }
1441 
1442  Diag(NameLoc, diag::err_redefinition) << Name;
1443  Diag(Def->getLocation(), diag::note_previous_definition);
1444  // FIXME: Would it make sense to try to "forget" the previous
1445  // definition, as part of error recovery?
1446  return true;
1447  }
1448  }
1449  } else if (PrevDecl) {
1450  // C++ [temp]p5:
1451  // A class template shall not have the same name as any other
1452  // template, class, function, object, enumeration, enumerator,
1453  // namespace, or type in the same scope (3.3), except as specified
1454  // in (14.5.4).
1455  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1456  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1457  return true;
1458  }
1459 
1460  // Check the template parameter list of this declaration, possibly
1461  // merging in the template parameter list from the previous class
1462  // template declaration. Skip this check for a friend in a dependent
1463  // context, because the template parameter list might be dependent.
1464  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1465  CheckTemplateParameterList(
1466  TemplateParams,
1467  PrevClassTemplate ? PrevClassTemplate->getTemplateParameters()
1468  : nullptr,
1469  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1470  SemanticContext->isDependentContext())
1471  ? TPC_ClassTemplateMember
1472  : TUK == TUK_Friend ? TPC_FriendClassTemplate
1473  : TPC_ClassTemplate))
1474  Invalid = true;
1475 
1476  if (SS.isSet()) {
1477  // If the name of the template was qualified, we must be defining the
1478  // template out-of-line.
1479  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1480  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1481  : diag::err_member_decl_does_not_match)
1482  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1483  Invalid = true;
1484  }
1485  }
1486 
1487  // If this is a templated friend in a dependent context we should not put it
1488  // on the redecl chain. In some cases, the templated friend can be the most
1489  // recent declaration tricking the template instantiator to make substitutions
1490  // there.
1491  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1492  bool ShouldAddRedecl
1493  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1494 
1495  CXXRecordDecl *NewClass =
1496  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1497  PrevClassTemplate && ShouldAddRedecl ?
1498  PrevClassTemplate->getTemplatedDecl() : nullptr,
1499  /*DelayTypeCreation=*/true);
1500  SetNestedNameSpecifier(NewClass, SS);
1501  if (NumOuterTemplateParamLists > 0)
1503  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1504  NumOuterTemplateParamLists));
1505 
1506  // Add alignment attributes if necessary; these attributes are checked when
1507  // the ASTContext lays out the structure.
1508  if (TUK == TUK_Definition) {
1509  AddAlignmentAttributesForRecord(NewClass);
1510  AddMsStructLayoutForRecord(NewClass);
1511  }
1512 
1513  // Attach the associated constraints when the declaration will not be part of
1514  // a decl chain.
1515  Expr *const ACtoAttach =
1516  PrevClassTemplate && ShouldAddRedecl ? nullptr : CurAC;
1517 
1518  ClassTemplateDecl *NewTemplate
1519  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1520  DeclarationName(Name), TemplateParams,
1521  NewClass, ACtoAttach);
1522 
1523  if (ShouldAddRedecl)
1524  NewTemplate->setPreviousDecl(PrevClassTemplate);
1525 
1526  NewClass->setDescribedClassTemplate(NewTemplate);
1527 
1528  if (ModulePrivateLoc.isValid())
1529  NewTemplate->setModulePrivate();
1530 
1531  // Build the type for the class template declaration now.
1533  T = Context.getInjectedClassNameType(NewClass, T);
1534  assert(T->isDependentType() && "Class template type is not dependent?");
1535  (void)T;
1536 
1537  // If we are providing an explicit specialization of a member that is a
1538  // class template, make a note of that.
1539  if (PrevClassTemplate &&
1540  PrevClassTemplate->getInstantiatedFromMemberTemplate())
1541  PrevClassTemplate->setMemberSpecialization();
1542 
1543  // Set the access specifier.
1544  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1545  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1546 
1547  // Set the lexical context of these templates
1548  NewClass->setLexicalDeclContext(CurContext);
1549  NewTemplate->setLexicalDeclContext(CurContext);
1550 
1551  if (TUK == TUK_Definition)
1552  NewClass->startDefinition();
1553 
1554  if (Attr)
1555  ProcessDeclAttributeList(S, NewClass, Attr);
1556 
1557  if (PrevClassTemplate)
1558  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1559 
1560  AddPushedVisibilityAttribute(NewClass);
1561 
1562  if (TUK != TUK_Friend) {
1563  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
1564  Scope *Outer = S;
1565  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
1566  Outer = Outer->getParent();
1567  PushOnScopeChains(NewTemplate, Outer);
1568  } else {
1569  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1570  NewTemplate->setAccess(PrevClassTemplate->getAccess());
1571  NewClass->setAccess(PrevClassTemplate->getAccess());
1572  }
1573 
1574  NewTemplate->setObjectOfFriendDecl();
1575 
1576  // Friend templates are visible in fairly strange ways.
1577  if (!CurContext->isDependentContext()) {
1578  DeclContext *DC = SemanticContext->getRedeclContext();
1579  DC->makeDeclVisibleInContext(NewTemplate);
1580  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1581  PushOnScopeChains(NewTemplate, EnclosingScope,
1582  /* AddToContext = */ false);
1583  }
1584 
1585  FriendDecl *Friend = FriendDecl::Create(
1586  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
1587  Friend->setAccess(AS_public);
1588  CurContext->addDecl(Friend);
1589  }
1590 
1591  if (PrevClassTemplate)
1592  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
1593 
1594  if (Invalid) {
1595  NewTemplate->setInvalidDecl();
1596  NewClass->setInvalidDecl();
1597  }
1598 
1599  ActOnDocumentableDecl(NewTemplate);
1600 
1601  return NewTemplate;
1602 }
1603 
1604 namespace {
1605 /// Transform to convert portions of a constructor declaration into the
1606 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
1607 struct ConvertConstructorToDeductionGuideTransform {
1608  ConvertConstructorToDeductionGuideTransform(Sema &S,
1609  ClassTemplateDecl *Template)
1610  : SemaRef(S), Template(Template) {}
1611 
1612  Sema &SemaRef;
1613  ClassTemplateDecl *Template;
1614 
1615  DeclContext *DC = Template->getDeclContext();
1616  CXXRecordDecl *Primary = Template->getTemplatedDecl();
1617  DeclarationName DeductionGuideName =
1619 
1620  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
1621 
1622  // Index adjustment to apply to convert depth-1 template parameters into
1623  // depth-0 template parameters.
1624  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
1625 
1626  /// Transform a constructor declaration into a deduction guide.
1627  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
1628  CXXConstructorDecl *CD) {
1630 
1631  LocalInstantiationScope Scope(SemaRef);
1632 
1633  // C++ [over.match.class.deduct]p1:
1634  // -- For each constructor of the class template designated by the
1635  // template-name, a function template with the following properties:
1636 
1637  // -- The template parameters are the template parameters of the class
1638  // template followed by the template parameters (including default
1639  // template arguments) of the constructor, if any.
1640  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
1641  if (FTD) {
1642  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
1643  SmallVector<NamedDecl *, 16> AllParams;
1644  AllParams.reserve(TemplateParams->size() + InnerParams->size());
1645  AllParams.insert(AllParams.begin(),
1646  TemplateParams->begin(), TemplateParams->end());
1647  SubstArgs.reserve(InnerParams->size());
1648 
1649  // Later template parameters could refer to earlier ones, so build up
1650  // a list of substituted template arguments as we go.
1651  for (NamedDecl *Param : *InnerParams) {
1653  Args.addOuterTemplateArguments(SubstArgs);
1654  Args.addOuterRetainedLevel();
1655  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
1656  if (!NewParam)
1657  return nullptr;
1658  AllParams.push_back(NewParam);
1659  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
1660  SemaRef.Context.getInjectedTemplateArg(NewParam)));
1661  }
1662  TemplateParams = TemplateParameterList::Create(
1663  SemaRef.Context, InnerParams->getTemplateLoc(),
1664  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
1665  /*FIXME: RequiresClause*/ nullptr);
1666  }
1667 
1668  // If we built a new template-parameter-list, track that we need to
1669  // substitute references to the old parameters into references to the
1670  // new ones.
1672  if (FTD) {
1673  Args.addOuterTemplateArguments(SubstArgs);
1674  Args.addOuterRetainedLevel();
1675  }
1676 
1679  assert(FPTL && "no prototype for constructor declaration");
1680 
1681  // Transform the type of the function, adjusting the return type and
1682  // replacing references to the old parameters with references to the
1683  // new ones.
1684  TypeLocBuilder TLB;
1686  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args);
1687  if (NewType.isNull())
1688  return nullptr;
1689  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
1690 
1691  return buildDeductionGuide(TemplateParams, CD->isExplicit(), NewTInfo,
1692  CD->getLocStart(), CD->getLocation(),
1693  CD->getLocEnd());
1694  }
1695 
1696  /// Build a deduction guide with the specified parameter types.
1697  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
1698  SourceLocation Loc = Template->getLocation();
1699 
1700  // Build the requested type.
1702  EPI.HasTrailingReturn = true;
1703  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
1704  DeductionGuideName, EPI);
1705  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
1706 
1707  FunctionProtoTypeLoc FPTL =
1709 
1710  // Build the parameters, needed during deduction / substitution.
1712  for (auto T : ParamTypes) {
1713  ParmVarDecl *NewParam = ParmVarDecl::Create(
1714  SemaRef.Context, DC, Loc, Loc, nullptr, T,
1715  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
1716  NewParam->setScopeInfo(0, Params.size());
1717  FPTL.setParam(Params.size(), NewParam);
1718  Params.push_back(NewParam);
1719  }
1720 
1721  return buildDeductionGuide(Template->getTemplateParameters(), false, TSI,
1722  Loc, Loc, Loc);
1723  }
1724 
1725 private:
1726  /// Transform a constructor template parameter into a deduction guide template
1727  /// parameter, rebuilding any internal references to earlier parameters and
1728  /// renumbering as we go.
1729  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
1731  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
1732  // TemplateTypeParmDecl's index cannot be changed after creation, so
1733  // substitute it directly.
1734  auto *NewTTP = TemplateTypeParmDecl::Create(
1735  SemaRef.Context, DC, TTP->getLocStart(), TTP->getLocation(),
1736  /*Depth*/0, Depth1IndexAdjustment + TTP->getIndex(),
1737  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
1738  TTP->isParameterPack());
1739  if (TTP->hasDefaultArgument()) {
1740  TypeSourceInfo *InstantiatedDefaultArg =
1741  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
1742  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
1743  if (InstantiatedDefaultArg)
1744  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
1745  }
1746  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
1747  NewTTP);
1748  return NewTTP;
1749  }
1750 
1751  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
1752  return transformTemplateParameterImpl(TTP, Args);
1753 
1754  return transformTemplateParameterImpl(
1755  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
1756  }
1757  template<typename TemplateParmDecl>
1758  TemplateParmDecl *
1759  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
1761  // Ask the template instantiator to do the heavy lifting for us, then adjust
1762  // the index of the parameter once it's done.
1763  auto *NewParam =
1764  cast_or_null<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
1765  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
1766  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
1767  return NewParam;
1768  }
1769 
1770  QualType transformFunctionProtoType(TypeLocBuilder &TLB,
1774  SmallVector<QualType, 4> ParamTypes;
1775  const FunctionProtoType *T = TL.getTypePtr();
1776 
1777  // -- The types of the function parameters are those of the constructor.
1778  for (auto *OldParam : TL.getParams()) {
1779  ParmVarDecl *NewParam = transformFunctionTypeParam(OldParam, Args);
1780  if (!NewParam)
1781  return QualType();
1782  ParamTypes.push_back(NewParam->getType());
1783  Params.push_back(NewParam);
1784  }
1785 
1786  // -- The return type is the class template specialization designated by
1787  // the template-name and template arguments corresponding to the
1788  // template parameters obtained from the class template.
1789  //
1790  // We use the injected-class-name type of the primary template instead.
1791  // This has the convenient property that it is different from any type that
1792  // the user can write in a deduction-guide (because they cannot enter the
1793  // context of the template), so implicit deduction guides can never collide
1794  // with explicit ones.
1795  QualType ReturnType = DeducedType;
1796  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
1797 
1798  // Resolving a wording defect, we also inherit the variadicness of the
1799  // constructor.
1801  EPI.Variadic = T->isVariadic();
1802  EPI.HasTrailingReturn = true;
1803 
1804  QualType Result = SemaRef.BuildFunctionType(
1805  ReturnType, ParamTypes, TL.getLocStart(), DeductionGuideName, EPI);
1806  if (Result.isNull())
1807  return QualType();
1808 
1809  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
1811  NewTL.setLParenLoc(TL.getLParenLoc());
1812  NewTL.setRParenLoc(TL.getRParenLoc());
1814  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
1815  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
1816  NewTL.setParam(I, Params[I]);
1817 
1818  return Result;
1819  }
1820 
1821  ParmVarDecl *
1822  transformFunctionTypeParam(ParmVarDecl *OldParam,
1824  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
1825  TypeSourceInfo *NewDI;
1826  if (!Args.getNumLevels())
1827  NewDI = OldDI;
1828  else if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
1829  // Expand out the one and only element in each inner pack.
1830  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
1831  NewDI =
1832  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
1833  OldParam->getLocation(), OldParam->getDeclName());
1834  if (!NewDI) return nullptr;
1835  NewDI =
1836  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
1837  PackTL.getTypePtr()->getNumExpansions());
1838  } else
1839  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
1840  OldParam->getDeclName());
1841  if (!NewDI)
1842  return nullptr;
1843 
1844  // Canonicalize the type. This (for instance) replaces references to
1845  // typedef members of the current instantiations with the definitions of
1846  // those typedefs, avoiding triggering instantiation of the deduced type
1847  // during deduction.
1848  // FIXME: It would be preferable to retain type sugar and source
1849  // information here (and handle this in substitution instead).
1850  NewDI = SemaRef.Context.getTrivialTypeSourceInfo(
1851  SemaRef.Context.getCanonicalType(NewDI->getType()),
1852  OldParam->getLocation());
1853 
1854  // Resolving a wording defect, we also inherit default arguments from the
1855  // constructor.
1856  ExprResult NewDefArg;
1857  if (OldParam->hasDefaultArg()) {
1858  NewDefArg = Args.getNumLevels()
1859  ? SemaRef.SubstExpr(OldParam->getDefaultArg(), Args)
1860  : OldParam->getDefaultArg();
1861  if (NewDefArg.isInvalid())
1862  return nullptr;
1863  }
1864 
1865  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
1866  OldParam->getInnerLocStart(),
1867  OldParam->getLocation(),
1868  OldParam->getIdentifier(),
1869  NewDI->getType(),
1870  NewDI,
1871  OldParam->getStorageClass(),
1872  NewDefArg.get());
1873  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
1874  OldParam->getFunctionScopeIndex());
1875  return NewParam;
1876  }
1877 
1878  NamedDecl *buildDeductionGuide(TemplateParameterList *TemplateParams,
1879  bool Explicit, TypeSourceInfo *TInfo,
1880  SourceLocation LocStart, SourceLocation Loc,
1881  SourceLocation LocEnd) {
1882  DeclarationNameInfo Name(DeductionGuideName, Loc);
1883  ArrayRef<ParmVarDecl *> Params =
1884  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
1885 
1886  // Build the implicit deduction guide template.
1887  auto *Guide =
1888  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, Explicit,
1889  Name, TInfo->getType(), TInfo, LocEnd);
1890  Guide->setImplicit();
1891  Guide->setParams(Params);
1892 
1893  for (auto *Param : Params)
1894  Param->setDeclContext(Guide);
1895 
1896  auto *GuideTemplate = FunctionTemplateDecl::Create(
1897  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
1898  GuideTemplate->setImplicit();
1899  Guide->setDescribedFunctionTemplate(GuideTemplate);
1900 
1901  if (isa<CXXRecordDecl>(DC)) {
1902  Guide->setAccess(AS_public);
1903  GuideTemplate->setAccess(AS_public);
1904  }
1905 
1906  DC->addDecl(GuideTemplate);
1907  return GuideTemplate;
1908  }
1909 };
1910 }
1911 
1913  SourceLocation Loc) {
1914  DeclContext *DC = Template->getDeclContext();
1915  if (DC->isDependentContext())
1916  return;
1917 
1918  ConvertConstructorToDeductionGuideTransform Transform(
1919  *this, cast<ClassTemplateDecl>(Template));
1920  if (!isCompleteType(Loc, Transform.DeducedType))
1921  return;
1922 
1923  // Check whether we've already declared deduction guides for this template.
1924  // FIXME: Consider storing a flag on the template to indicate this.
1925  auto Existing = DC->lookup(Transform.DeductionGuideName);
1926  for (auto *D : Existing)
1927  if (D->isImplicit())
1928  return;
1929 
1930  // In case we were expanding a pack when we attempted to declare deduction
1931  // guides, turn off pack expansion for everything we're about to do.
1932  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
1933  // Create a template instantiation record to track the "instantiation" of
1934  // constructors into deduction guides.
1935  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
1936  // this substitution process actually fail?
1937  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
1938 
1939  // Convert declared constructors into deduction guide templates.
1940  // FIXME: Skip constructors for which deduction must necessarily fail (those
1941  // for which some class template parameter without a default argument never
1942  // appears in a deduced context).
1943  bool AddedAny = false;
1944  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
1945  D = D->getUnderlyingDecl();
1946  if (D->isInvalidDecl() || D->isImplicit())
1947  continue;
1948  D = cast<NamedDecl>(D->getCanonicalDecl());
1949 
1950  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
1951  auto *CD =
1952  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
1953  // Class-scope explicit specializations (MS extension) do not result in
1954  // deduction guides.
1955  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
1956  continue;
1957 
1958  Transform.transformConstructor(FTD, CD);
1959  AddedAny = true;
1960  }
1961 
1962  // C++17 [over.match.class.deduct]
1963  // -- If C is not defined or does not declare any constructors, an
1964  // additional function template derived as above from a hypothetical
1965  // constructor C().
1966  if (!AddedAny)
1967  Transform.buildSimpleDeductionGuide(None);
1968 
1969  // -- An additional function template derived as above from a hypothetical
1970  // constructor C(C), called the copy deduction candidate.
1971  cast<CXXDeductionGuideDecl>(
1972  cast<FunctionTemplateDecl>(
1973  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
1974  ->getTemplatedDecl())
1975  ->setIsCopyDeductionCandidate();
1976 }
1977 
1978 /// \brief Diagnose the presence of a default template argument on a
1979 /// template parameter, which is ill-formed in certain contexts.
1980 ///
1981 /// \returns true if the default template argument should be dropped.
1984  SourceLocation ParamLoc,
1985  SourceRange DefArgRange) {
1986  switch (TPC) {
1988  case Sema::TPC_VarTemplate:
1990  return false;
1991 
1994  // C++ [temp.param]p9:
1995  // A default template-argument shall not be specified in a
1996  // function template declaration or a function template
1997  // definition [...]
1998  // If a friend function template declaration specifies a default
1999  // template-argument, that declaration shall be a definition and shall be
2000  // the only declaration of the function template in the translation unit.
2001  // (C++98/03 doesn't have this wording; see DR226).
2002  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2003  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2004  : diag::ext_template_parameter_default_in_function_template)
2005  << DefArgRange;
2006  return false;
2007 
2009  // C++0x [temp.param]p9:
2010  // A default template-argument shall not be specified in the
2011  // template-parameter-lists of the definition of a member of a
2012  // class template that appears outside of the member's class.
2013  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2014  << DefArgRange;
2015  return true;
2016 
2019  // C++ [temp.param]p9:
2020  // A default template-argument shall not be specified in a
2021  // friend template declaration.
2022  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2023  << DefArgRange;
2024  return true;
2025 
2026  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2027  // for friend function templates if there is only a single
2028  // declaration (and it is a definition). Strange!
2029  }
2030 
2031  llvm_unreachable("Invalid TemplateParamListContext!");
2032 }
2033 
2034 /// \brief Check for unexpanded parameter packs within the template parameters
2035 /// of a template template parameter, recursively.
2037  TemplateTemplateParmDecl *TTP) {
2038  // A template template parameter which is a parameter pack is also a pack
2039  // expansion.
2040  if (TTP->isParameterPack())
2041  return false;
2042 
2044  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2045  NamedDecl *P = Params->getParam(I);
2046  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2047  if (!NTTP->isParameterPack() &&
2048  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2049  NTTP->getTypeSourceInfo(),
2051  return true;
2052 
2053  continue;
2054  }
2055 
2056  if (TemplateTemplateParmDecl *InnerTTP
2057  = dyn_cast<TemplateTemplateParmDecl>(P))
2058  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2059  return true;
2060  }
2061 
2062  return false;
2063 }
2064 
2065 /// \brief Checks the validity of a template parameter list, possibly
2066 /// considering the template parameter list from a previous
2067 /// declaration.
2068 ///
2069 /// If an "old" template parameter list is provided, it must be
2070 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2071 /// template parameter list.
2072 ///
2073 /// \param NewParams Template parameter list for a new template
2074 /// declaration. This template parameter list will be updated with any
2075 /// default arguments that are carried through from the previous
2076 /// template parameter list.
2077 ///
2078 /// \param OldParams If provided, template parameter list from a
2079 /// previous declaration of the same template. Default template
2080 /// arguments will be merged from the old template parameter list to
2081 /// the new template parameter list.
2082 ///
2083 /// \param TPC Describes the context in which we are checking the given
2084 /// template parameter list.
2085 ///
2086 /// \returns true if an error occurred, false otherwise.
2088  TemplateParameterList *OldParams,
2090  bool Invalid = false;
2091 
2092  // C++ [temp.param]p10:
2093  // The set of default template-arguments available for use with a
2094  // template declaration or definition is obtained by merging the
2095  // default arguments from the definition (if in scope) and all
2096  // declarations in scope in the same way default function
2097  // arguments are (8.3.6).
2098  bool SawDefaultArgument = false;
2099  SourceLocation PreviousDefaultArgLoc;
2100 
2101  // Dummy initialization to avoid warnings.
2102  TemplateParameterList::iterator OldParam = NewParams->end();
2103  if (OldParams)
2104  OldParam = OldParams->begin();
2105 
2106  bool RemoveDefaultArguments = false;
2107  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2108  NewParamEnd = NewParams->end();
2109  NewParam != NewParamEnd; ++NewParam) {
2110  // Variables used to diagnose redundant default arguments
2111  bool RedundantDefaultArg = false;
2112  SourceLocation OldDefaultLoc;
2113  SourceLocation NewDefaultLoc;
2114 
2115  // Variable used to diagnose missing default arguments
2116  bool MissingDefaultArg = false;
2117 
2118  // Variable used to diagnose non-final parameter packs
2119  bool SawParameterPack = false;
2120 
2121  if (TemplateTypeParmDecl *NewTypeParm
2122  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2123  // Check the presence of a default argument here.
2124  if (NewTypeParm->hasDefaultArgument() &&
2126  NewTypeParm->getLocation(),
2127  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2128  .getSourceRange()))
2129  NewTypeParm->removeDefaultArgument();
2130 
2131  // Merge default arguments for template type parameters.
2132  TemplateTypeParmDecl *OldTypeParm
2133  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2134  if (NewTypeParm->isParameterPack()) {
2135  assert(!NewTypeParm->hasDefaultArgument() &&
2136  "Parameter packs can't have a default argument!");
2137  SawParameterPack = true;
2138  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2139  NewTypeParm->hasDefaultArgument()) {
2140  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2141  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2142  SawDefaultArgument = true;
2143  RedundantDefaultArg = true;
2144  PreviousDefaultArgLoc = NewDefaultLoc;
2145  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2146  // Merge the default argument from the old declaration to the
2147  // new declaration.
2148  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2149  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2150  } else if (NewTypeParm->hasDefaultArgument()) {
2151  SawDefaultArgument = true;
2152  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2153  } else if (SawDefaultArgument)
2154  MissingDefaultArg = true;
2155  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2156  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2157  // Check for unexpanded parameter packs.
2158  if (!NewNonTypeParm->isParameterPack() &&
2159  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2160  NewNonTypeParm->getTypeSourceInfo(),
2161  UPPC_NonTypeTemplateParameterType)) {
2162  Invalid = true;
2163  continue;
2164  }
2165 
2166  // Check the presence of a default argument here.
2167  if (NewNonTypeParm->hasDefaultArgument() &&
2169  NewNonTypeParm->getLocation(),
2170  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2171  NewNonTypeParm->removeDefaultArgument();
2172  }
2173 
2174  // Merge default arguments for non-type template parameters
2175  NonTypeTemplateParmDecl *OldNonTypeParm
2176  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2177  if (NewNonTypeParm->isParameterPack()) {
2178  assert(!NewNonTypeParm->hasDefaultArgument() &&
2179  "Parameter packs can't have a default argument!");
2180  if (!NewNonTypeParm->isPackExpansion())
2181  SawParameterPack = true;
2182  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2183  NewNonTypeParm->hasDefaultArgument()) {
2184  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2185  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2186  SawDefaultArgument = true;
2187  RedundantDefaultArg = true;
2188  PreviousDefaultArgLoc = NewDefaultLoc;
2189  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2190  // Merge the default argument from the old declaration to the
2191  // new declaration.
2192  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2193  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2194  } else if (NewNonTypeParm->hasDefaultArgument()) {
2195  SawDefaultArgument = true;
2196  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2197  } else if (SawDefaultArgument)
2198  MissingDefaultArg = true;
2199  } else {
2200  TemplateTemplateParmDecl *NewTemplateParm
2201  = cast<TemplateTemplateParmDecl>(*NewParam);
2202 
2203  // Check for unexpanded parameter packs, recursively.
2204  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2205  Invalid = true;
2206  continue;
2207  }
2208 
2209  // Check the presence of a default argument here.
2210  if (NewTemplateParm->hasDefaultArgument() &&
2212  NewTemplateParm->getLocation(),
2213  NewTemplateParm->getDefaultArgument().getSourceRange()))
2214  NewTemplateParm->removeDefaultArgument();
2215 
2216  // Merge default arguments for template template parameters
2217  TemplateTemplateParmDecl *OldTemplateParm
2218  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2219  if (NewTemplateParm->isParameterPack()) {
2220  assert(!NewTemplateParm->hasDefaultArgument() &&
2221  "Parameter packs can't have a default argument!");
2222  if (!NewTemplateParm->isPackExpansion())
2223  SawParameterPack = true;
2224  } else if (OldTemplateParm &&
2225  hasVisibleDefaultArgument(OldTemplateParm) &&
2226  NewTemplateParm->hasDefaultArgument()) {
2227  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2228  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2229  SawDefaultArgument = true;
2230  RedundantDefaultArg = true;
2231  PreviousDefaultArgLoc = NewDefaultLoc;
2232  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2233  // Merge the default argument from the old declaration to the
2234  // new declaration.
2235  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2236  PreviousDefaultArgLoc
2237  = OldTemplateParm->getDefaultArgument().getLocation();
2238  } else if (NewTemplateParm->hasDefaultArgument()) {
2239  SawDefaultArgument = true;
2240  PreviousDefaultArgLoc
2241  = NewTemplateParm->getDefaultArgument().getLocation();
2242  } else if (SawDefaultArgument)
2243  MissingDefaultArg = true;
2244  }
2245 
2246  // C++11 [temp.param]p11:
2247  // If a template parameter of a primary class template or alias template
2248  // is a template parameter pack, it shall be the last template parameter.
2249  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2250  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2251  TPC == TPC_TypeAliasTemplate)) {
2252  Diag((*NewParam)->getLocation(),
2253  diag::err_template_param_pack_must_be_last_template_parameter);
2254  Invalid = true;
2255  }
2256 
2257  if (RedundantDefaultArg) {
2258  // C++ [temp.param]p12:
2259  // A template-parameter shall not be given default arguments
2260  // by two different declarations in the same scope.
2261  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2262  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2263  Invalid = true;
2264  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2265  // C++ [temp.param]p11:
2266  // If a template-parameter of a class template has a default
2267  // template-argument, each subsequent template-parameter shall either
2268  // have a default template-argument supplied or be a template parameter
2269  // pack.
2270  Diag((*NewParam)->getLocation(),
2271  diag::err_template_param_default_arg_missing);
2272  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2273  Invalid = true;
2274  RemoveDefaultArguments = true;
2275  }
2276 
2277  // If we have an old template parameter list that we're merging
2278  // in, move on to the next parameter.
2279  if (OldParams)
2280  ++OldParam;
2281  }
2282 
2283  // We were missing some default arguments at the end of the list, so remove
2284  // all of the default arguments.
2285  if (RemoveDefaultArguments) {
2286  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2287  NewParamEnd = NewParams->end();
2288  NewParam != NewParamEnd; ++NewParam) {
2289  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2290  TTP->removeDefaultArgument();
2291  else if (NonTypeTemplateParmDecl *NTTP
2292  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2293  NTTP->removeDefaultArgument();
2294  else
2295  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2296  }
2297  }
2298 
2299  return Invalid;
2300 }
2301 
2302 namespace {
2303 
2304 /// A class which looks for a use of a certain level of template
2305 /// parameter.
2306 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2308 
2309  unsigned Depth;
2310 
2311  // Whether we're looking for a use of a template parameter that makes the
2312  // overall construct type-dependent / a dependent type. This is strictly
2313  // best-effort for now; we may fail to match at all for a dependent type
2314  // in some cases if this is set.
2315  bool IgnoreNonTypeDependent;
2316 
2317  bool Match;
2318  SourceLocation MatchLoc;
2319 
2320  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2321  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2322  Match(false) {}
2323 
2324  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2325  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2326  NamedDecl *ND = Params->getParam(0);
2327  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2328  Depth = PD->getDepth();
2329  } else if (NonTypeTemplateParmDecl *PD =
2330  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2331  Depth = PD->getDepth();
2332  } else {
2333  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2334  }
2335  }
2336 
2337  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2338  if (ParmDepth >= Depth) {
2339  Match = true;
2340  MatchLoc = Loc;
2341  return true;
2342  }
2343  return false;
2344  }
2345 
2346  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2347  // Prune out non-type-dependent expressions if requested. This can
2348  // sometimes result in us failing to find a template parameter reference
2349  // (if a value-dependent expression creates a dependent type), but this
2350  // mode is best-effort only.
2351  if (auto *E = dyn_cast_or_null<Expr>(S))
2352  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2353  return true;
2354  return super::TraverseStmt(S, Q);
2355  }
2356 
2357  bool TraverseTypeLoc(TypeLoc TL) {
2358  if (IgnoreNonTypeDependent && !TL.isNull() &&
2359  !TL.getType()->isDependentType())
2360  return true;
2361  return super::TraverseTypeLoc(TL);
2362  }
2363 
2364  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2365  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2366  }
2367 
2368  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2369  // For a best-effort search, keep looking until we find a location.
2370  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2371  }
2372 
2373  bool TraverseTemplateName(TemplateName N) {
2374  if (TemplateTemplateParmDecl *PD =
2375  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2376  if (Matches(PD->getDepth()))
2377  return false;
2378  return super::TraverseTemplateName(N);
2379  }
2380 
2381  bool VisitDeclRefExpr(DeclRefExpr *E) {
2382  if (NonTypeTemplateParmDecl *PD =
2383  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2384  if (Matches(PD->getDepth(), E->getExprLoc()))
2385  return false;
2386  return super::VisitDeclRefExpr(E);
2387  }
2388 
2389  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2390  return TraverseType(T->getReplacementType());
2391  }
2392 
2393  bool
2394  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2395  return TraverseTemplateArgument(T->getArgumentPack());
2396  }
2397 
2398  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2399  return TraverseType(T->getInjectedSpecializationType());
2400  }
2401 };
2402 } // end anonymous namespace
2403 
2404 /// Determines whether a given type depends on the given parameter
2405 /// list.
2406 static bool
2408  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2409  Checker.TraverseType(T);
2410  return Checker.Match;
2411 }
2412 
2413 // Find the source range corresponding to the named type in the given
2414 // nested-name-specifier, if any.
2416  QualType T,
2417  const CXXScopeSpec &SS) {
2419  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2420  if (const Type *CurType = NNS->getAsType()) {
2421  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2422  return NNSLoc.getTypeLoc().getSourceRange();
2423  } else
2424  break;
2425 
2426  NNSLoc = NNSLoc.getPrefix();
2427  }
2428 
2429  return SourceRange();
2430 }
2431 
2432 /// \brief Match the given template parameter lists to the given scope
2433 /// specifier, returning the template parameter list that applies to the
2434 /// name.
2435 ///
2436 /// \param DeclStartLoc the start of the declaration that has a scope
2437 /// specifier or a template parameter list.
2438 ///
2439 /// \param DeclLoc The location of the declaration itself.
2440 ///
2441 /// \param SS the scope specifier that will be matched to the given template
2442 /// parameter lists. This scope specifier precedes a qualified name that is
2443 /// being declared.
2444 ///
2445 /// \param TemplateId The template-id following the scope specifier, if there
2446 /// is one. Used to check for a missing 'template<>'.
2447 ///
2448 /// \param ParamLists the template parameter lists, from the outermost to the
2449 /// innermost template parameter lists.
2450 ///
2451 /// \param IsFriend Whether to apply the slightly different rules for
2452 /// matching template parameters to scope specifiers in friend
2453 /// declarations.
2454 ///
2455 /// \param IsMemberSpecialization will be set true if the scope specifier
2456 /// denotes a fully-specialized type, and therefore this is a declaration of
2457 /// a member specialization.
2458 ///
2459 /// \returns the template parameter list, if any, that corresponds to the
2460 /// name that is preceded by the scope specifier @p SS. This template
2461 /// parameter list may have template parameters (if we're declaring a
2462 /// template) or may have no template parameters (if we're declaring a
2463 /// template specialization), or may be NULL (if what we're declaring isn't
2464 /// itself a template).
2466  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
2467  TemplateIdAnnotation *TemplateId,
2468  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
2469  bool &IsMemberSpecialization, bool &Invalid) {
2470  IsMemberSpecialization = false;
2471  Invalid = false;
2472 
2473  // The sequence of nested types to which we will match up the template
2474  // parameter lists. We first build this list by starting with the type named
2475  // by the nested-name-specifier and walking out until we run out of types.
2476  SmallVector<QualType, 4> NestedTypes;
2477  QualType T;
2478  if (SS.getScopeRep()) {
2479  if (CXXRecordDecl *Record
2480  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
2481  T = Context.getTypeDeclType(Record);
2482  else
2483  T = QualType(SS.getScopeRep()->getAsType(), 0);
2484  }
2485 
2486  // If we found an explicit specialization that prevents us from needing
2487  // 'template<>' headers, this will be set to the location of that
2488  // explicit specialization.
2489  SourceLocation ExplicitSpecLoc;
2490 
2491  while (!T.isNull()) {
2492  NestedTypes.push_back(T);
2493 
2494  // Retrieve the parent of a record type.
2495  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2496  // If this type is an explicit specialization, we're done.
2498  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2499  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
2500  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
2501  ExplicitSpecLoc = Spec->getLocation();
2502  break;
2503  }
2504  } else if (Record->getTemplateSpecializationKind()
2506  ExplicitSpecLoc = Record->getLocation();
2507  break;
2508  }
2509 
2510  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
2511  T = Context.getTypeDeclType(Parent);
2512  else
2513  T = QualType();
2514  continue;
2515  }
2516 
2517  if (const TemplateSpecializationType *TST
2519  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2520  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
2521  T = Context.getTypeDeclType(Parent);
2522  else
2523  T = QualType();
2524  continue;
2525  }
2526  }
2527 
2528  // Look one step prior in a dependent template specialization type.
2529  if (const DependentTemplateSpecializationType *DependentTST
2531  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
2532  T = QualType(NNS->getAsType(), 0);
2533  else
2534  T = QualType();
2535  continue;
2536  }
2537 
2538  // Look one step prior in a dependent name type.
2539  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
2540  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
2541  T = QualType(NNS->getAsType(), 0);
2542  else
2543  T = QualType();
2544  continue;
2545  }
2546 
2547  // Retrieve the parent of an enumeration type.
2548  if (const EnumType *EnumT = T->getAs<EnumType>()) {
2549  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
2550  // check here.
2551  EnumDecl *Enum = EnumT->getDecl();
2552 
2553  // Get to the parent type.
2554  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
2555  T = Context.getTypeDeclType(Parent);
2556  else
2557  T = QualType();
2558  continue;
2559  }
2560 
2561  T = QualType();
2562  }
2563  // Reverse the nested types list, since we want to traverse from the outermost
2564  // to the innermost while checking template-parameter-lists.
2565  std::reverse(NestedTypes.begin(), NestedTypes.end());
2566 
2567  // C++0x [temp.expl.spec]p17:
2568  // A member or a member template may be nested within many
2569  // enclosing class templates. In an explicit specialization for
2570  // such a member, the member declaration shall be preceded by a
2571  // template<> for each enclosing class template that is
2572  // explicitly specialized.
2573  bool SawNonEmptyTemplateParameterList = false;
2574 
2575  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
2576  if (SawNonEmptyTemplateParameterList) {
2577  Diag(DeclLoc, diag::err_specialize_member_of_template)
2578  << !Recovery << Range;
2579  Invalid = true;
2580  IsMemberSpecialization = false;
2581  return true;
2582  }
2583 
2584  return false;
2585  };
2586 
2587  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
2588  // Check that we can have an explicit specialization here.
2589  if (CheckExplicitSpecialization(Range, true))
2590  return true;
2591 
2592  // We don't have a template header, but we should.
2593  SourceLocation ExpectedTemplateLoc;
2594  if (!ParamLists.empty())
2595  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
2596  else
2597  ExpectedTemplateLoc = DeclStartLoc;
2598 
2599  Diag(DeclLoc, diag::err_template_spec_needs_header)
2600  << Range
2601  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
2602  return false;
2603  };
2604 
2605  unsigned ParamIdx = 0;
2606  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
2607  ++TypeIdx) {
2608  T = NestedTypes[TypeIdx];
2609 
2610  // Whether we expect a 'template<>' header.
2611  bool NeedEmptyTemplateHeader = false;
2612 
2613  // Whether we expect a template header with parameters.
2614  bool NeedNonemptyTemplateHeader = false;
2615 
2616  // For a dependent type, the set of template parameters that we
2617  // expect to see.
2618  TemplateParameterList *ExpectedTemplateParams = nullptr;
2619 
2620  // C++0x [temp.expl.spec]p15:
2621  // A member or a member template may be nested within many enclosing
2622  // class templates. In an explicit specialization for such a member, the
2623  // member declaration shall be preceded by a template<> for each
2624  // enclosing class template that is explicitly specialized.
2625  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2627  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
2628  ExpectedTemplateParams = Partial->getTemplateParameters();
2629  NeedNonemptyTemplateHeader = true;
2630  } else if (Record->isDependentType()) {
2631  if (Record->getDescribedClassTemplate()) {
2632  ExpectedTemplateParams = Record->getDescribedClassTemplate()
2633  ->getTemplateParameters();
2634  NeedNonemptyTemplateHeader = true;
2635  }
2636  } else if (ClassTemplateSpecializationDecl *Spec
2637  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2638  // C++0x [temp.expl.spec]p4:
2639  // Members of an explicitly specialized class template are defined
2640  // in the same manner as members of normal classes, and not using
2641  // the template<> syntax.
2642  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
2643  NeedEmptyTemplateHeader = true;
2644  else
2645  continue;
2646  } else if (Record->getTemplateSpecializationKind()) {
2647  if (Record->getTemplateSpecializationKind()
2649  TypeIdx == NumTypes - 1)
2650  IsMemberSpecialization = true;
2651 
2652  continue;
2653  }
2654  } else if (const TemplateSpecializationType *TST
2656  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2657  ExpectedTemplateParams = Template->getTemplateParameters();
2658  NeedNonemptyTemplateHeader = true;
2659  }
2660  } else if (T->getAs<DependentTemplateSpecializationType>()) {
2661  // FIXME: We actually could/should check the template arguments here
2662  // against the corresponding template parameter list.
2663  NeedNonemptyTemplateHeader = false;
2664  }
2665 
2666  // C++ [temp.expl.spec]p16:
2667  // In an explicit specialization declaration for a member of a class
2668  // template or a member template that ap- pears in namespace scope, the
2669  // member template and some of its enclosing class templates may remain
2670  // unspecialized, except that the declaration shall not explicitly
2671  // specialize a class member template if its en- closing class templates
2672  // are not explicitly specialized as well.
2673  if (ParamIdx < ParamLists.size()) {
2674  if (ParamLists[ParamIdx]->size() == 0) {
2675  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2676  false))
2677  return nullptr;
2678  } else
2679  SawNonEmptyTemplateParameterList = true;
2680  }
2681 
2682  if (NeedEmptyTemplateHeader) {
2683  // If we're on the last of the types, and we need a 'template<>' header
2684  // here, then it's a member specialization.
2685  if (TypeIdx == NumTypes - 1)
2686  IsMemberSpecialization = true;
2687 
2688  if (ParamIdx < ParamLists.size()) {
2689  if (ParamLists[ParamIdx]->size() > 0) {
2690  // The header has template parameters when it shouldn't. Complain.
2691  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2692  diag::err_template_param_list_matches_nontemplate)
2693  << T
2694  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
2695  ParamLists[ParamIdx]->getRAngleLoc())
2696  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2697  Invalid = true;
2698  return nullptr;
2699  }
2700 
2701  // Consume this template header.
2702  ++ParamIdx;
2703  continue;
2704  }
2705 
2706  if (!IsFriend)
2707  if (DiagnoseMissingExplicitSpecialization(
2708  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
2709  return nullptr;
2710 
2711  continue;
2712  }
2713 
2714  if (NeedNonemptyTemplateHeader) {
2715  // In friend declarations we can have template-ids which don't
2716  // depend on the corresponding template parameter lists. But
2717  // assume that empty parameter lists are supposed to match this
2718  // template-id.
2719  if (IsFriend && T->isDependentType()) {
2720  if (ParamIdx < ParamLists.size() &&
2721  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
2722  ExpectedTemplateParams = nullptr;
2723  else
2724  continue;
2725  }
2726 
2727  if (ParamIdx < ParamLists.size()) {
2728  // Check the template parameter list, if we can.
2729  if (ExpectedTemplateParams &&
2730  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
2731  ExpectedTemplateParams,
2732  true, TPL_TemplateMatch))
2733  Invalid = true;
2734 
2735  if (!Invalid &&
2736  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
2737  TPC_ClassTemplateMember))
2738  Invalid = true;
2739 
2740  ++ParamIdx;
2741  continue;
2742  }
2743 
2744  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
2745  << T
2746  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2747  Invalid = true;
2748  continue;
2749  }
2750  }
2751 
2752  // If there were at least as many template-ids as there were template
2753  // parameter lists, then there are no template parameter lists remaining for
2754  // the declaration itself.
2755  if (ParamIdx >= ParamLists.size()) {
2756  if (TemplateId && !IsFriend) {
2757  // We don't have a template header for the declaration itself, but we
2758  // should.
2759  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
2760  TemplateId->RAngleLoc));
2761 
2762  // Fabricate an empty template parameter list for the invented header.
2764  SourceLocation(), None,
2765  SourceLocation(), nullptr);
2766  }
2767 
2768  return nullptr;
2769  }
2770 
2771  // If there were too many template parameter lists, complain about that now.
2772  if (ParamIdx < ParamLists.size() - 1) {
2773  bool HasAnyExplicitSpecHeader = false;
2774  bool AllExplicitSpecHeaders = true;
2775  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
2776  if (ParamLists[I]->size() == 0)
2777  HasAnyExplicitSpecHeader = true;
2778  else
2779  AllExplicitSpecHeaders = false;
2780  }
2781 
2782  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2783  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
2784  : diag::err_template_spec_extra_headers)
2785  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
2786  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
2787 
2788  // If there was a specialization somewhere, such that 'template<>' is
2789  // not required, and there were any 'template<>' headers, note where the
2790  // specialization occurred.
2791  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
2792  Diag(ExplicitSpecLoc,
2793  diag::note_explicit_template_spec_does_not_need_header)
2794  << NestedTypes.back();
2795 
2796  // We have a template parameter list with no corresponding scope, which
2797  // means that the resulting template declaration can't be instantiated
2798  // properly (we'll end up with dependent nodes when we shouldn't).
2799  if (!AllExplicitSpecHeaders)
2800  Invalid = true;
2801  }
2802 
2803  // C++ [temp.expl.spec]p16:
2804  // In an explicit specialization declaration for a member of a class
2805  // template or a member template that ap- pears in namespace scope, the
2806  // member template and some of its enclosing class templates may remain
2807  // unspecialized, except that the declaration shall not explicitly
2808  // specialize a class member template if its en- closing class templates
2809  // are not explicitly specialized as well.
2810  if (ParamLists.back()->size() == 0 &&
2811  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2812  false))
2813  return nullptr;
2814 
2815  // Return the last template parameter list, which corresponds to the
2816  // entity being declared.
2817  return ParamLists.back();
2818 }
2819 
2821  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
2822  Diag(Template->getLocation(), diag::note_template_declared_here)
2823  << (isa<FunctionTemplateDecl>(Template)
2824  ? 0
2825  : isa<ClassTemplateDecl>(Template)
2826  ? 1
2827  : isa<VarTemplateDecl>(Template)
2828  ? 2
2829  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
2830  << Template->getDeclName();
2831  return;
2832  }
2833 
2835  for (OverloadedTemplateStorage::iterator I = OST->begin(),
2836  IEnd = OST->end();
2837  I != IEnd; ++I)
2838  Diag((*I)->getLocation(), diag::note_template_declared_here)
2839  << 0 << (*I)->getDeclName();
2840 
2841  return;
2842  }
2843 }
2844 
2845 static QualType
2847  const SmallVectorImpl<TemplateArgument> &Converted,
2848  SourceLocation TemplateLoc,
2849  TemplateArgumentListInfo &TemplateArgs) {
2850  ASTContext &Context = SemaRef.getASTContext();
2851  switch (BTD->getBuiltinTemplateKind()) {
2852  case BTK__make_integer_seq: {
2853  // Specializations of __make_integer_seq<S, T, N> are treated like
2854  // S<T, 0, ..., N-1>.
2855 
2856  // C++14 [inteseq.intseq]p1:
2857  // T shall be an integer type.
2858  if (!Converted[1].getAsType()->isIntegralType(Context)) {
2859  SemaRef.Diag(TemplateArgs[1].getLocation(),
2860  diag::err_integer_sequence_integral_element_type);
2861  return QualType();
2862  }
2863 
2864  // C++14 [inteseq.make]p1:
2865  // If N is negative the program is ill-formed.
2866  TemplateArgument NumArgsArg = Converted[2];
2867  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
2868  if (NumArgs < 0) {
2869  SemaRef.Diag(TemplateArgs[2].getLocation(),
2870  diag::err_integer_sequence_negative_length);
2871  return QualType();
2872  }
2873 
2874  QualType ArgTy = NumArgsArg.getIntegralType();
2875  TemplateArgumentListInfo SyntheticTemplateArgs;
2876  // The type argument gets reused as the first template argument in the
2877  // synthetic template argument list.
2878  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
2879  // Expand N into 0 ... N-1.
2880  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
2881  I < NumArgs; ++I) {
2882  TemplateArgument TA(Context, I, ArgTy);
2883  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
2884  TA, ArgTy, TemplateArgs[2].getLocation()));
2885  }
2886  // The first template argument will be reused as the template decl that
2887  // our synthetic template arguments will be applied to.
2888  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
2889  TemplateLoc, SyntheticTemplateArgs);
2890  }
2891 
2893  // Specializations of
2894  // __type_pack_element<Index, T_1, ..., T_N>
2895  // are treated like T_Index.
2896  assert(Converted.size() == 2 &&
2897  "__type_pack_element should be given an index and a parameter pack");
2898 
2899  // If the Index is out of bounds, the program is ill-formed.
2900  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
2901  llvm::APSInt Index = IndexArg.getAsIntegral();
2902  assert(Index >= 0 && "the index used with __type_pack_element should be of "
2903  "type std::size_t, and hence be non-negative");
2904  if (Index >= Ts.pack_size()) {
2905  SemaRef.Diag(TemplateArgs[0].getLocation(),
2906  diag::err_type_pack_element_out_of_bounds);
2907  return QualType();
2908  }
2909 
2910  // We simply return the type at index `Index`.
2911  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
2912  return Nth->getAsType();
2913  }
2914  llvm_unreachable("unexpected BuiltinTemplateDecl!");
2915 }
2916 
2917 /// Determine whether this alias template is "enable_if_t".
2918 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
2919  return AliasTemplate->getName().equals("enable_if_t");
2920 }
2921 
2922 /// Collect all of the separable terms in the given condition, which
2923 /// might be a conjunction.
2924 ///
2925 /// FIXME: The right answer is to convert the logical expression into
2926 /// disjunctive normal form, so we can find the first failed term
2927 /// within each possible clause.
2928 static void collectConjunctionTerms(Expr *Clause,
2929  SmallVectorImpl<Expr *> &Terms) {
2930  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
2931  if (BinOp->getOpcode() == BO_LAnd) {
2932  collectConjunctionTerms(BinOp->getLHS(), Terms);
2933  collectConjunctionTerms(BinOp->getRHS(), Terms);
2934  }
2935 
2936  return;
2937  }
2938 
2939  Terms.push_back(Clause);
2940 }
2941 
2942 // The ranges-v3 library uses an odd pattern of a top-level "||" with
2943 // a left-hand side that is value-dependent but never true. Identify
2944 // the idiom and ignore that term.
2946  // Top-level '||'.
2947  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
2948  if (!BinOp) return Cond;
2949 
2950  if (BinOp->getOpcode() != BO_LOr) return Cond;
2951 
2952  // With an inner '==' that has a literal on the right-hand side.
2953  Expr *LHS = BinOp->getLHS();
2954  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
2955  if (!InnerBinOp) return Cond;
2956 
2957  if (InnerBinOp->getOpcode() != BO_EQ ||
2958  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
2959  return Cond;
2960 
2961  // If the inner binary operation came from a macro expansion named
2962  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
2963  // of the '||', which is the real, user-provided condition.
2964  SourceLocation Loc = InnerBinOp->getExprLoc();
2965  if (!Loc.isMacroID()) return Cond;
2966 
2967  StringRef MacroName = PP.getImmediateMacroName(Loc);
2968  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
2969  return BinOp->getRHS();
2970 
2971  return Cond;
2972 }
2973 
2974 std::pair<Expr *, std::string>
2975 Sema::findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond) {
2976  Cond = lookThroughRangesV3Condition(PP, Cond);
2977 
2978  // Separate out all of the terms in a conjunction.
2979  SmallVector<Expr *, 4> Terms;
2980  collectConjunctionTerms(Cond, Terms);
2981 
2982  // Determine which term failed.
2983  Expr *FailedCond = nullptr;
2984  for (Expr *Term : Terms) {
2985  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
2986 
2987  // Literals are uninteresting.
2988  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
2989  isa<IntegerLiteral>(TermAsWritten))
2990  continue;
2991 
2992  // The initialization of the parameter from the argument is
2993  // a constant-evaluated context.
2994  EnterExpressionEvaluationContext ConstantEvaluated(
2996 
2997  bool Succeeded;
2998  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
2999  !Succeeded) {
3000  FailedCond = TermAsWritten;
3001  break;
3002  }
3003  }
3004 
3005  if (!FailedCond) {
3006  if (!AllowTopLevelCond)
3007  return { nullptr, "" };
3008 
3009  FailedCond = Cond->IgnoreParenImpCasts();
3010  }
3011 
3012  std::string Description;
3013  {
3014  llvm::raw_string_ostream Out(Description);
3015  FailedCond->printPretty(Out, nullptr, getPrintingPolicy());
3016  }
3017  return { FailedCond, Description };
3018 }
3019 
3021  SourceLocation TemplateLoc,
3022  TemplateArgumentListInfo &TemplateArgs) {
3025  if (DTN && DTN->isIdentifier())
3026  // When building a template-id where the template-name is dependent,
3027  // assume the template is a type template. Either our assumption is
3028  // correct, or the code is ill-formed and will be diagnosed when the
3029  // dependent name is substituted.
3031  DTN->getQualifier(),
3032  DTN->getIdentifier(),
3033  TemplateArgs);
3034 
3035  TemplateDecl *Template = Name.getAsTemplateDecl();
3036  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3037  isa<VarTemplateDecl>(Template)) {
3038  // We might have a substituted template template parameter pack. If so,
3039  // build a template specialization type for it.
3041  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3042 
3043  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3044  << Name;
3045  NoteAllFoundTemplates(Name);
3046  return QualType();
3047  }
3048 
3049  // Check that the template argument list is well-formed for this
3050  // template.
3052  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3053  false, Converted))
3054  return QualType();
3055 
3056  QualType CanonType;
3057 
3058  bool InstantiationDependent = false;
3059  if (TypeAliasTemplateDecl *AliasTemplate =
3060  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3061  // Find the canonical type for this type alias template specialization.
3062  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3063  if (Pattern->isInvalidDecl())
3064  return QualType();
3065 
3067  Converted);
3068 
3069  // Only substitute for the innermost template argument list.
3070  MultiLevelTemplateArgumentList TemplateArgLists;
3071  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3072  unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
3073  for (unsigned I = 0; I < Depth; ++I)
3074  TemplateArgLists.addOuterTemplateArguments(None);
3075 
3077  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3078  if (Inst.isInvalid())
3079  return QualType();
3080 
3081  CanonType = SubstType(Pattern->getUnderlyingType(),
3082  TemplateArgLists, AliasTemplate->getLocation(),
3083  AliasTemplate->getDeclName());
3084  if (CanonType.isNull()) {
3085  // If this was enable_if and we failed to find the nested type
3086  // within enable_if in a SFINAE context, dig out the specific
3087  // enable_if condition that failed and present that instead.
3088  if (isEnableIfAliasTemplate(AliasTemplate)) {
3089  if (auto DeductionInfo = isSFINAEContext()) {
3090  if (*DeductionInfo &&
3091  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3092  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3093  diag::err_typename_nested_not_found_enable_if &&
3094  TemplateArgs[0].getArgument().getKind()
3096  Expr *FailedCond;
3097  std::string FailedDescription;
3098  std::tie(FailedCond, FailedDescription) =
3099  findFailedBooleanCondition(
3100  TemplateArgs[0].getSourceExpression(),
3101  /*AllowTopLevelCond=*/true);
3102 
3103  // Remove the old SFINAE diagnostic.
3104  PartialDiagnosticAt OldDiag =
3106  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3107 
3108  // Add a new SFINAE diagnostic specifying which condition
3109  // failed.
3110  (*DeductionInfo)->addSFINAEDiagnostic(
3111  OldDiag.first,
3112  PDiag(diag::err_typename_nested_not_found_requirement)
3113  << FailedDescription
3114  << FailedCond->getSourceRange());
3115  }
3116  }
3117  }
3118 
3119  return QualType();
3120  }
3121  } else if (Name.isDependent() ||
3123  TemplateArgs, InstantiationDependent)) {
3124  // This class template specialization is a dependent
3125  // type. Therefore, its canonical type is another class template
3126  // specialization type that contains all of the converted
3127  // arguments in canonical form. This ensures that, e.g., A<T> and
3128  // A<T, T> have identical types when A is declared as:
3129  //
3130  // template<typename T, typename U = T> struct A;
3131  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3132 
3133  // This might work out to be a current instantiation, in which
3134  // case the canonical type needs to be the InjectedClassNameType.
3135  //
3136  // TODO: in theory this could be a simple hashtable lookup; most
3137  // changes to CurContext don't change the set of current
3138  // instantiations.
3139  if (isa<ClassTemplateDecl>(Template)) {
3140  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3141  // If we get out to a namespace, we're done.
3142  if (Ctx->isFileContext()) break;
3143 
3144  // If this isn't a record, keep looking.
3145  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3146  if (!Record) continue;
3147 
3148  // Look for one of the two cases with InjectedClassNameTypes
3149  // and check whether it's the same template.
3150  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3151  !Record->getDescribedClassTemplate())
3152  continue;
3153 
3154  // Fetch the injected class name type and check whether its
3155  // injected type is equal to the type we just built.
3156  QualType ICNT = Context.getTypeDeclType(Record);
3157  QualType Injected = cast<InjectedClassNameType>(ICNT)
3158  ->getInjectedSpecializationType();
3159 
3160  if (CanonType != Injected->getCanonicalTypeInternal())
3161  continue;
3162 
3163  // If so, the canonical type of this TST is the injected
3164  // class name type of the record we just found.
3165  assert(ICNT.isCanonical());
3166  CanonType = ICNT;
3167  break;
3168  }
3169  }
3170  } else if (ClassTemplateDecl *ClassTemplate
3171  = dyn_cast<ClassTemplateDecl>(Template)) {
3172  // Find the class template specialization declaration that
3173  // corresponds to these arguments.
3174  void *InsertPos = nullptr;
3176  = ClassTemplate->findSpecialization(Converted, InsertPos);
3177  if (!Decl) {
3178  // This is the first time we have referenced this class template
3179  // specialization. Create the canonical declaration and add it to
3180  // the set of specializations.
3182  ClassTemplate->getTemplatedDecl()->getTagKind(),
3183  ClassTemplate->getDeclContext(),
3184  ClassTemplate->getTemplatedDecl()->getLocStart(),
3185  ClassTemplate->getLocation(),
3186  ClassTemplate,
3187  Converted, nullptr);
3188  ClassTemplate->AddSpecialization(Decl, InsertPos);
3189  if (ClassTemplate->isOutOfLine())
3190  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3191  }
3192 
3193  if (Decl->getSpecializationKind() == TSK_Undeclared) {
3194  MultiLevelTemplateArgumentList TemplateArgLists;
3195  TemplateArgLists.addOuterTemplateArguments(Converted);
3196  InstantiateAttrsForDecl(TemplateArgLists, ClassTemplate->getTemplatedDecl(),
3197  Decl);
3198  }
3199 
3200  // Diagnose uses of this specialization.
3201  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3202 
3203  CanonType = Context.getTypeDeclType(Decl);
3204  assert(isa<RecordType>(CanonType) &&
3205  "type of non-dependent specialization is not a RecordType");
3206  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3207  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3208  TemplateArgs);
3209  }
3210 
3211  // Build the fully-sugared type for this class template
3212  // specialization, which refers back to the class template
3213  // specialization we created or found.
3214  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3215 }
3216 
3217 TypeResult
3219  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3220  SourceLocation TemplateIILoc,
3221  SourceLocation LAngleLoc,
3222  ASTTemplateArgsPtr TemplateArgsIn,
3223  SourceLocation RAngleLoc,
3224  bool IsCtorOrDtorName, bool IsClassName) {
3225  if (SS.isInvalid())
3226  return true;
3227 
3228  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3229  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3230 
3231  // C++ [temp.res]p3:
3232  // A qualified-id that refers to a type and in which the
3233  // nested-name-specifier depends on a template-parameter (14.6.2)
3234  // shall be prefixed by the keyword typename to indicate that the
3235  // qualified-id denotes a type, forming an
3236  // elaborated-type-specifier (7.1.5.3).
3237  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3238  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3239  << SS.getScopeRep() << TemplateII->getName();
3240  // Recover as if 'typename' were specified.
3241  // FIXME: This is not quite correct recovery as we don't transform SS
3242  // into the corresponding dependent form (and we don't diagnose missing
3243  // 'template' keywords within SS as a result).
3244  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3245  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3246  TemplateArgsIn, RAngleLoc);
3247  }
3248 
3249  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3250  // it's not actually allowed to be used as a type in most cases. Because
3251  // we annotate it before we know whether it's valid, we have to check for
3252  // this case here.
3253  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3254  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3255  Diag(TemplateIILoc,
3256  TemplateKWLoc.isInvalid()
3257  ? diag::err_out_of_line_qualified_id_type_names_constructor
3258  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3259  << TemplateII << 0 /*injected-class-name used as template name*/
3260  << 1 /*if any keyword was present, it was 'template'*/;
3261  }
3262  }
3263 
3264  TemplateName Template = TemplateD.get();
3265 
3266  // Translate the parser's template argument list in our AST format.
3267  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3268  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3269 
3270  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3271  QualType T
3273  DTN->getQualifier(),
3274  DTN->getIdentifier(),
3275  TemplateArgs);
3276  // Build type-source information.
3277  TypeLocBuilder TLB;
3281  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3282  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3283  SpecTL.setTemplateNameLoc(TemplateIILoc);
3284  SpecTL.setLAngleLoc(LAngleLoc);
3285  SpecTL.setRAngleLoc(RAngleLoc);
3286  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3287  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3288  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3289  }
3290 
3291  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3292  if (Result.isNull())
3293  return true;
3294 
3295  // Build type-source information.
3296  TypeLocBuilder TLB;
3298  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3299  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3300  SpecTL.setTemplateNameLoc(TemplateIILoc);
3301  SpecTL.setLAngleLoc(LAngleLoc);
3302  SpecTL.setRAngleLoc(RAngleLoc);
3303  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3304  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3305 
3306  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3307  // constructor or destructor name (in such a case, the scope specifier
3308  // will be attached to the enclosing Decl or Expr node).
3309  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3310  // Create an elaborated-type-specifier containing the nested-name-specifier.
3311  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3312  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3314  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3315  }
3316 
3317  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3318 }
3319 
3321  TypeSpecifierType TagSpec,
3322  SourceLocation TagLoc,
3323  CXXScopeSpec &SS,
3324  SourceLocation TemplateKWLoc,
3325  TemplateTy TemplateD,
3326  SourceLocation TemplateLoc,
3327  SourceLocation LAngleLoc,
3328  ASTTemplateArgsPtr TemplateArgsIn,
3329  SourceLocation RAngleLoc) {
3330  TemplateName Template = TemplateD.get();
3331 
3332  // Translate the parser's template argument list in our AST format.
3333  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3334  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3335 
3336  // Determine the tag kind
3338  ElaboratedTypeKeyword Keyword
3340 
3341  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3343  DTN->getQualifier(),
3344  DTN->getIdentifier(),
3345  TemplateArgs);
3346 
3347  // Build type-source information.
3348  TypeLocBuilder TLB;
3351  SpecTL.setElaboratedKeywordLoc(TagLoc);
3352  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3353  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3354  SpecTL.setTemplateNameLoc(TemplateLoc);
3355  SpecTL.setLAngleLoc(LAngleLoc);
3356  SpecTL.setRAngleLoc(RAngleLoc);
3357  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3358  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3359  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3360  }
3361 
3362  if (TypeAliasTemplateDecl *TAT =
3363  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
3364  // C++0x [dcl.type.elab]p2:
3365  // If the identifier resolves to a typedef-name or the simple-template-id
3366  // resolves to an alias template specialization, the
3367  // elaborated-type-specifier is ill-formed.
3368  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
3369  << TAT << NTK_TypeAliasTemplate << TagKind;
3370  Diag(TAT->getLocation(), diag::note_declared_at);
3371  }
3372 
3373  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
3374  if (Result.isNull())
3375  return TypeResult(true);
3376 
3377  // Check the tag kind
3378  if (const RecordType *RT = Result->getAs<RecordType>()) {
3379  RecordDecl *D = RT->getDecl();
3380 
3382  assert(Id && "templated class must have an identifier");
3383 
3384  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
3385  TagLoc, Id)) {
3386  Diag(TagLoc, diag::err_use_with_wrong_tag)
3387  << Result
3389  Diag(D->getLocation(), diag::note_previous_use);
3390  }
3391  }
3392 
3393  // Provide source-location information for the template specialization.
3394  TypeLocBuilder TLB;
3396  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3397  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3398  SpecTL.setTemplateNameLoc(TemplateLoc);
3399  SpecTL.setLAngleLoc(LAngleLoc);
3400  SpecTL.setRAngleLoc(RAngleLoc);
3401  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3402  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3403 
3404  // Construct an elaborated type containing the nested-name-specifier (if any)
3405  // and tag keyword.
3406  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
3407  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3408  ElabTL.setElaboratedKeywordLoc(TagLoc);
3409  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3410  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3411 }
3412 
3413 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
3414  NamedDecl *PrevDecl,
3415  SourceLocation Loc,
3417 
3419 
3421  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
3422  switch (Arg.getKind()) {
3429  return false;
3430 
3431  case TemplateArgument::Type: {
3432  QualType Type = Arg.getAsType();
3433  const TemplateTypeParmType *TPT =
3435  return TPT && !Type.hasQualifiers() &&
3436  TPT->getDepth() == Depth && TPT->getIndex() == Index;
3437  }
3438 
3440  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
3441  if (!DRE || !DRE->getDecl())
3442  return false;
3443  const NonTypeTemplateParmDecl *NTTP =
3444  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
3445  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
3446  }
3447 
3449  const TemplateTemplateParmDecl *TTP =
3450  dyn_cast_or_null<TemplateTemplateParmDecl>(
3452  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
3453  }
3454  llvm_unreachable("unexpected kind of template argument");
3455 }
3456 
3459  if (Params->size() != Args.size())
3460  return false;
3461 
3462  unsigned Depth = Params->getDepth();
3463 
3464  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
3465  TemplateArgument Arg = Args[I];
3466 
3467  // If the parameter is a pack expansion, the argument must be a pack
3468  // whose only element is a pack expansion.
3469  if (Params->getParam(I)->isParameterPack()) {
3470  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
3471  !Arg.pack_begin()->isPackExpansion())
3472  return false;
3473  Arg = Arg.pack_begin()->getPackExpansionPattern();
3474  }
3475 
3476  if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
3477  return false;
3478  }
3479 
3480  return true;
3481 }
3482 
3483 /// Convert the parser's template argument list representation into our form.
3486  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
3487  TemplateId.RAngleLoc);
3488  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
3489  TemplateId.NumArgs);
3490  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
3491  return TemplateArgs;
3492 }
3493 
3494 template<typename PartialSpecDecl>
3495 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
3496  if (Partial->getDeclContext()->isDependentContext())
3497  return;
3498 
3499  // FIXME: Get the TDK from deduction in order to provide better diagnostics
3500  // for non-substitution-failure issues?
3501  TemplateDeductionInfo Info(Partial->getLocation());
3502  if (S.isMoreSpecializedThanPrimary(Partial, Info))
3503  return;
3504 
3505  auto *Template = Partial->getSpecializedTemplate();
3506  S.Diag(Partial->getLocation(),
3507  diag::ext_partial_spec_not_more_specialized_than_primary)
3508  << isa<VarTemplateDecl>(Template);
3509 
3510  if (Info.hasSFINAEDiagnostic()) {
3513  Info.takeSFINAEDiagnostic(Diag);
3514  SmallString<128> SFINAEArgString;
3515  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
3516  S.Diag(Diag.first,
3517  diag::note_partial_spec_not_more_specialized_than_primary)
3518  << SFINAEArgString;
3519  }
3520 
3521  S.Diag(Template->getLocation(), diag::note_template_decl_here);
3522 }
3523 
3524 static void
3526  const llvm::SmallBitVector &DeducibleParams) {
3527  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
3528  if (!DeducibleParams[I]) {
3529  NamedDecl *Param = TemplateParams->getParam(I);
3530  if (Param->getDeclName())
3531  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3532  << Param->getDeclName();
3533  else
3534  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3535  << "(anonymous)";
3536  }
3537  }
3538 }
3539 
3540 
3541 template<typename PartialSpecDecl>
3543  PartialSpecDecl *Partial) {
3544  // C++1z [temp.class.spec]p8: (DR1495)
3545  // - The specialization shall be more specialized than the primary
3546  // template (14.5.5.2).
3547  checkMoreSpecializedThanPrimary(S, Partial);
3548 
3549  // C++ [temp.class.spec]p8: (DR1315)
3550  // - Each template-parameter shall appear at least once in the
3551  // template-id outside a non-deduced context.
3552  // C++1z [temp.class.spec.match]p3 (P0127R2)
3553  // If the template arguments of a partial specialization cannot be
3554  // deduced because of the structure of its template-parameter-list
3555  // and the template-id, the program is ill-formed.
3556  auto *TemplateParams = Partial->getTemplateParameters();
3557  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3558  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
3559  TemplateParams->getDepth(), DeducibleParams);
3560 
3561  if (!DeducibleParams.all()) {
3562  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3563  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
3564  << isa<VarTemplatePartialSpecializationDecl>(Partial)
3565  << (NumNonDeducible > 1)
3566  << SourceRange(Partial->getLocation(),
3567  Partial->getTemplateArgsAsWritten()->RAngleLoc);
3568  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
3569  }
3570 }
3571 
3574  checkTemplatePartialSpecialization(*this, Partial);
3575 }
3576 
3579  checkTemplatePartialSpecialization(*this, Partial);
3580 }
3581 
3583  // C++1z [temp.param]p11:
3584  // A template parameter of a deduction guide template that does not have a
3585  // default-argument shall be deducible from the parameter-type-list of the
3586  // deduction guide template.
3587  auto *TemplateParams = TD->getTemplateParameters();
3588  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3589  MarkDeducedTemplateParameters(TD, DeducibleParams);
3590  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
3591  // A parameter pack is deducible (to an empty pack).
3592  auto *Param = TemplateParams->getParam(I);
3593  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
3594  DeducibleParams[I] = true;
3595  }
3596 
3597  if (!DeducibleParams.all()) {
3598  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3599  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
3600  << (NumNonDeducible > 1);
3601  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
3602  }
3603 }
3604 
3606  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
3607  TemplateParameterList *TemplateParams, StorageClass SC,
3608  bool IsPartialSpecialization) {
3609  // D must be variable template id.
3611  "Variable template specialization is declared with a template it.");
3612 
3613  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
3614  TemplateArgumentListInfo TemplateArgs =
3615  makeTemplateArgumentListInfo(*this, *TemplateId);
3616  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
3617  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
3618  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
3619 
3620  TemplateName Name = TemplateId->Template.get();
3621 
3622  // The template-id must name a variable template.
3623  VarTemplateDecl *VarTemplate =
3624  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
3625  if (!VarTemplate) {
3626  NamedDecl *FnTemplate;
3627  if (auto *OTS = Name.getAsOverloadedTemplate())
3628  FnTemplate = *OTS->begin();
3629  else
3630  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
3631  if (FnTemplate)
3632  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
3633  << FnTemplate->getDeclName();
3634  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
3635  << IsPartialSpecialization;
3636  }
3637 
3638  // Check for unexpanded parameter packs in any of the template arguments.
3639  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
3640  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
3641  UPPC_PartialSpecialization))
3642  return true;
3643 
3644  // Check that the template argument list is well-formed for this
3645  // template.
3647  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
3648  false, Converted))
3649  return true;
3650 
3651  // Find the variable template (partial) specialization declaration that
3652  // corresponds to these arguments.
3653  if (IsPartialSpecialization) {
3654  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
3655  TemplateArgs.size(), Converted))
3656  return true;
3657 
3658  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
3659  // also do them during instantiation.
3660  bool InstantiationDependent;
3661  if (!Name.isDependent() &&
3663  TemplateArgs.arguments(),
3664  InstantiationDependent)) {
3665  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
3666  << VarTemplate->getDeclName();
3667  IsPartialSpecialization = false;
3668  }
3669 
3671  Converted)) {
3672  // C++ [temp.class.spec]p9b3:
3673  //
3674  // -- The argument list of the specialization shall not be identical
3675  // to the implicit argument list of the primary template.
3676  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
3677  << /*variable template*/ 1
3678  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
3679  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
3680  // FIXME: Recover from this by treating the declaration as a redeclaration
3681  // of the primary template.
3682  return true;
3683  }
3684  }
3685 
3686  void *InsertPos = nullptr;
3687  VarTemplateSpecializationDecl *PrevDecl = nullptr;
3688 
3689  if (IsPartialSpecialization)
3690  // FIXME: Template parameter list matters too
3691  PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
3692  else
3693  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
3694 
3695  VarTemplateSpecializationDecl *Specialization = nullptr;
3696 
3697  // Check whether we can declare a variable template specialization in
3698  // the current scope.
3699  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
3700  TemplateNameLoc,
3701  IsPartialSpecialization))
3702  return true;
3703 
3704  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
3705  // Since the only prior variable template specialization with these
3706  // arguments was referenced but not declared, reuse that
3707  // declaration node as our own, updating its source location and
3708  // the list of outer template parameters to reflect our new declaration.
3709  Specialization = PrevDecl;
3710  Specialization->setLocation(TemplateNameLoc);
3711  PrevDecl = nullptr;
3712  } else if (IsPartialSpecialization) {
3713  // Create a new class template partial specialization declaration node.
3715  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
3718  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
3719  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
3720  Converted, TemplateArgs);
3721 
3722  if (!PrevPartial)
3723  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
3724  Specialization = Partial;
3725 
3726  // If we are providing an explicit specialization of a member variable
3727  // template specialization, make a note of that.
3728  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
3729  PrevPartial->setMemberSpecialization();
3730 
3731  CheckTemplatePartialSpecialization(Partial);
3732  } else {
3733  // Create a new class template specialization declaration node for
3734  // this explicit specialization or friend declaration.
3735  Specialization = VarTemplateSpecializationDecl::Create(
3736  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
3737  VarTemplate, DI->getType(), DI, SC, Converted);
3738  Specialization->setTemplateArgsInfo(TemplateArgs);
3739 
3740  if (!PrevDecl)
3741  VarTemplate->AddSpecialization(Specialization, InsertPos);
3742  }
3743 
3744  // C++ [temp.expl.spec]p6:
3745  // If a template, a member template or the member of a class template is
3746  // explicitly specialized then that specialization shall be declared
3747  // before the first use of that specialization that would cause an implicit
3748  // instantiation to take place, in every translation unit in which such a
3749  // use occurs; no diagnostic is required.
3750  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
3751  bool Okay = false;
3752  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
3753  // Is there any previous explicit specialization declaration?
3755  Okay = true;
3756  break;
3757  }
3758  }
3759 
3760  if (!Okay) {
3761  SourceRange Range(TemplateNameLoc, RAngleLoc);
3762  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
3763  << Name << Range;
3764 
3765  Diag(PrevDecl->getPointOfInstantiation(),
3766  diag::note_instantiation_required_here)
3767  << (PrevDecl->getTemplateSpecializationKind() !=
3769  return true;
3770  }
3771  }
3772 
3773  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
3774  Specialization->setLexicalDeclContext(CurContext);
3775 
3776  // Add the specialization into its lexical context, so that it can
3777  // be seen when iterating through the list of declarations in that
3778  // context. However, specializations are not found by name lookup.
3779  CurContext->addDecl(Specialization);
3780 
3781  // Note that this is an explicit specialization.
3783 
3784  if (PrevDecl) {
3785  // Check that this isn't a redefinition of this specialization,
3786  // merging with previous declarations.
3787  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
3788  forRedeclarationInCurContext());
3789  PrevSpec.addDecl(PrevDecl);
3790  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
3791  } else if (Specialization->isStaticDataMember() &&
3792  Specialization->isOutOfLine()) {
3793  Specialization->setAccess(VarTemplate->getAccess());
3794  }
3795 
3796  // Link instantiations of static data members back to the template from
3797  // which they were instantiated.
3798  if (Specialization->isStaticDataMember())
3799  Specialization->setInstantiationOfStaticDataMember(
3800  VarTemplate->getTemplatedDecl(),
3801  Specialization->getSpecializationKind());
3802 
3803  return Specialization;
3804 }
3805 
3806 namespace {
3807 /// \brief A partial specialization whose template arguments have matched
3808 /// a given template-id.
3809 struct PartialSpecMatchResult {
3811  TemplateArgumentList *Args;
3812 };
3813 } // end anonymous namespace
3814 
3815 DeclResult
3817  SourceLocation TemplateNameLoc,
3818  const TemplateArgumentListInfo &TemplateArgs) {
3819  assert(Template && "A variable template id without template?");
3820 
3821  // Check that the template argument list is well-formed for this template.
3823  if (CheckTemplateArgumentList(
3824  Template, TemplateNameLoc,
3825  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
3826  Converted))
3827  return true;
3828 
3829  // Find the variable template specialization declaration that
3830  // corresponds to these arguments.
3831  void *InsertPos = nullptr;
3832  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
3833  Converted, InsertPos)) {
3834  checkSpecializationVisibility(TemplateNameLoc, Spec);
3835  // If we already have a variable template specialization, return it.
3836  return Spec;
3837  }
3838 
3839  // This is the first time we have referenced this variable template
3840  // specialization. Create the canonical declaration and add it to
3841  // the set of specializations, based on the closest partial specialization
3842  // that it represents. That is,
3843  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
3845  Converted);
3846  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
3847  bool AmbiguousPartialSpec = false;
3848  typedef PartialSpecMatchResult MatchResult;
3850  SourceLocation PointOfInstantiation = TemplateNameLoc;
3851  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
3852  /*ForTakingAddress=*/false);
3853 
3854  // 1. Attempt to find the closest partial specialization that this
3855  // specializes, if any.
3856  // If any of the template arguments is dependent, then this is probably
3857  // a placeholder for an incomplete declarative context; which must be
3858  // complete by instantiation time. Thus, do not search through the partial
3859  // specializations yet.
3860  // TODO: Unify with InstantiateClassTemplateSpecialization()?
3861  // Perhaps better after unification of DeduceTemplateArguments() and
3862  // getMoreSpecializedPartialSpecialization().
3863  bool InstantiationDependent = false;
3865  TemplateArgs, InstantiationDependent)) {
3866 
3868  Template->getPartialSpecializations(PartialSpecs);
3869 
3870  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
3871  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
3872  TemplateDeductionInfo Info(FailedCandidates.getLocation());
3873 
3874  if (TemplateDeductionResult Result =
3875  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
3876  // Store the failed-deduction information for use in diagnostics, later.
3877  // TODO: Actually use the failed-deduction info?
3878  FailedCandidates.addCandidate().set(
3879  DeclAccessPair::make(Template, AS_public), Partial,
3880  MakeDeductionFailureInfo(Context, Result, Info));
3881  (void)Result;
3882  } else {
3883  Matched.push_back(PartialSpecMatchResult());
3884  Matched.back().Partial = Partial;
3885  Matched.back().Args = Info.take();
3886  }
3887  }
3888 
3889  if (Matched.size() >= 1) {
3890  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
3891  if (Matched.size() == 1) {
3892  // -- If exactly one matching specialization is found, the
3893  // instantiation is generated from that specialization.
3894  // We don't need to do anything for this.
3895  } else {
3896  // -- If more than one matching specialization is found, the
3897  // partial order rules (14.5.4.2) are used to determine
3898  // whether one of the specializations is more specialized
3899  // than the others. If none of the specializations is more
3900  // specialized than all of the other matching
3901  // specializations, then the use of the variable template is
3902  // ambiguous and the program is ill-formed.
3903  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
3904  PEnd = Matched.end();
3905  P != PEnd; ++P) {
3906  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
3907  PointOfInstantiation) ==
3908  P->Partial)
3909  Best = P;
3910  }
3911 
3912  // Determine if the best partial specialization is more specialized than
3913  // the others.
3914  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
3915  PEnd = Matched.end();
3916  P != PEnd; ++P) {
3917  if (P != Best && getMoreSpecializedPartialSpecialization(
3918  P->Partial, Best->Partial,
3919  PointOfInstantiation) != Best->Partial) {
3920  AmbiguousPartialSpec = true;
3921  break;
3922  }
3923  }
3924  }
3925 
3926  // Instantiate using the best variable template partial specialization.
3927  InstantiationPattern = Best->Partial;
3928  InstantiationArgs = Best->Args;
3929  } else {
3930  // -- If no match is found, the instantiation is generated
3931  // from the primary template.
3932  // InstantiationPattern = Template->getTemplatedDecl();
3933  }
3934  }
3935 
3936  // 2. Create the canonical declaration.
3937  // Note that we do not instantiate a definition until we see an odr-use
3938  // in DoMarkVarDeclReferenced().
3939  // FIXME: LateAttrs et al.?
3940  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
3941  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
3942  Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
3943  if (!Decl)
3944  return true;
3945 
3946  if (AmbiguousPartialSpec) {
3947  // Partial ordering did not produce a clear winner. Complain.
3948  Decl->setInvalidDecl();
3949  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
3950  << Decl;
3951 
3952  // Print the matching partial specializations.
3953  for (MatchResult P : Matched)
3954  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
3955  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
3956  *P.Args);
3957  return true;
3958  }
3959 
3961  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
3962  Decl->setInstantiationOf(D, InstantiationArgs);
3963 
3964  checkSpecializationVisibility(TemplateNameLoc, Decl);
3965 
3966  assert(Decl && "No variable template specialization?");
3967  return Decl;
3968 }
3969 
3970 ExprResult
3972  const DeclarationNameInfo &NameInfo,
3973  VarTemplateDecl *Template, SourceLocation TemplateLoc,
3974  const TemplateArgumentListInfo *TemplateArgs) {
3975 
3976  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
3977  *TemplateArgs);
3978  if (Decl.isInvalid())
3979  return ExprError();
3980 
3981  VarDecl *Var = cast<VarDecl>(Decl.get());
3982  if (!Var->getTemplateSpecializationKind())
3984  NameInfo.getLoc());
3985 
3986  // Build an ordinary singleton decl ref.
3987  return BuildDeclarationNameExpr(SS, NameInfo, Var,
3988  /*FoundD=*/nullptr, TemplateArgs);
3989 }
3990 
3992  SourceLocation TemplateKWLoc,
3993  LookupResult &R,
3994  bool RequiresADL,
3995  const TemplateArgumentListInfo *TemplateArgs) {
3996  // FIXME: Can we do any checking at this point? I guess we could check the
3997  // template arguments that we have against the template name, if the template
3998  // name refers to a single template. That's not a terribly common case,
3999  // though.
4000  // foo<int> could identify a single function unambiguously
4001  // This approach does NOT work, since f<int>(1);
4002  // gets resolved prior to resorting to overload resolution
4003  // i.e., template<class T> void f(double);
4004  // vs template<class T, class U> void f(U);
4005 
4006  // These should be filtered out by our callers.
4007  assert(!R.empty() && "empty lookup results when building templateid");
4008  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4009 
4010  // In C++1y, check variable template ids.
4011  bool InstantiationDependent;
4012  if (R.getAsSingle<VarTemplateDecl>() &&
4014  *TemplateArgs, InstantiationDependent)) {
4015  return CheckVarTemplateId(SS, R.getLookupNameInfo(),
4017  TemplateKWLoc, TemplateArgs);
4018  }
4019 
4020  // We don't want lookup warnings at this point.
4021  R.suppressDiagnostics();
4022 
4025  SS.getWithLocInContext(Context),
4026  TemplateKWLoc,
4027  R.getLookupNameInfo(),
4028  RequiresADL, TemplateArgs,
4029  R.begin(), R.end());
4030 
4031  return ULE;
4032 }
4033 
4034 // We actually only call this from template instantiation.
4035 ExprResult
4037  SourceLocation TemplateKWLoc,
4038  const DeclarationNameInfo &NameInfo,
4039  const TemplateArgumentListInfo *TemplateArgs) {
4040 
4041  assert(TemplateArgs || TemplateKWLoc.isValid());
4042  DeclContext *DC;
4043  if (!(DC = computeDeclContext(SS, false)) ||
4044  DC->isDependentContext() ||
4045  RequireCompleteDeclContext(SS, DC))
4046  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4047 
4048  bool MemberOfUnknownSpecialization;
4049  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4050  LookupTemplateName(R, (Scope*)nullptr, SS, QualType(), /*Entering*/ false,
4051  MemberOfUnknownSpecialization);
4052 
4053  if (R.isAmbiguous())
4054  return ExprError();
4055 
4056  if (R.empty()) {
4057  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_non_template)
4058  << NameInfo.getName() << SS.getRange();
4059  return ExprError();
4060  }
4061 
4062  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4063  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4064  << SS.getScopeRep()
4065  << NameInfo.getName().getAsString() << SS.getRange();
4066  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4067  return ExprError();
4068  }
4069 
4070  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4071 }
4072 
4073 /// \brief Form a dependent template name.
4074 ///
4075 /// This action forms a dependent template name given the template
4076 /// name and its (presumably dependent) scope specifier. For
4077 /// example, given "MetaFun::template apply", the scope specifier \p
4078 /// SS will be "MetaFun::", \p TemplateKWLoc contains the location
4079 /// of the "template" keyword, and "apply" is the \p Name.
4081  CXXScopeSpec &SS,
4082  SourceLocation TemplateKWLoc,
4083  UnqualifiedId &Name,
4084  ParsedType ObjectType,
4085  bool EnteringContext,
4086  TemplateTy &Result,
4087  bool AllowInjectedClassName) {
4088  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4089  Diag(TemplateKWLoc,
4090  getLangOpts().CPlusPlus11 ?
4091  diag::warn_cxx98_compat_template_outside_of_template :
4092  diag::ext_template_outside_of_template)
4093  << FixItHint::CreateRemoval(TemplateKWLoc);
4094 
4095  DeclContext *LookupCtx = nullptr;
4096  if (SS.isSet())
4097  LookupCtx = computeDeclContext(SS, EnteringContext);
4098  if (!LookupCtx && ObjectType)
4099  LookupCtx = computeDeclContext(ObjectType.get());
4100  if (LookupCtx) {
4101  // C++0x [temp.names]p5:
4102  // If a name prefixed by the keyword template is not the name of
4103  // a template, the program is ill-formed. [Note: the keyword
4104  // template may not be applied to non-template members of class
4105  // templates. -end note ] [ Note: as is the case with the
4106  // typename prefix, the template prefix is allowed in cases
4107  // where it is not strictly necessary; i.e., when the
4108  // nested-name-specifier or the expression on the left of the ->
4109  // or . is not dependent on a template-parameter, or the use
4110  // does not appear in the scope of a template. -end note]
4111  //
4112  // Note: C++03 was more strict here, because it banned the use of
4113  // the "template" keyword prior to a template-name that was not a
4114  // dependent name. C++ DR468 relaxed this requirement (the
4115  // "template" keyword is now permitted). We follow the C++0x
4116  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4117  bool MemberOfUnknownSpecialization;
4118  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4119  ObjectType, EnteringContext, Result,
4120  MemberOfUnknownSpecialization);
4121  if (TNK == TNK_Non_template && LookupCtx->isDependentContext() &&
4122  isa<CXXRecordDecl>(LookupCtx) &&
4123  (!cast<CXXRecordDecl>(LookupCtx)->hasDefinition() ||
4124  cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases())) {
4125  // This is a dependent template. Handle it below.
4126  } else if (TNK == TNK_Non_template) {
4127  Diag(Name.getLocStart(),
4128  diag::err_template_kw_refers_to_non_template)
4129  << GetNameFromUnqualifiedId(Name).getName()
4130  << Name.getSourceRange()
4131  << TemplateKWLoc;
4132  return TNK_Non_template;
4133  } else {
4134  // We found something; return it.
4135  auto *LookupRD = dyn_cast<CXXRecordDecl>(LookupCtx);
4136  if (!AllowInjectedClassName && SS.isSet() && LookupRD &&
4138  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4139  // C++14 [class.qual]p2:
4140  // In a lookup in which function names are not ignored and the
4141  // nested-name-specifier nominates a class C, if the name specified
4142  // [...] is the injected-class-name of C, [...] the name is instead
4143  // considered to name the constructor
4144  //
4145  // We don't get here if naming the constructor would be valid, so we
4146  // just reject immediately and recover by treating the
4147  // injected-class-name as naming the template.
4148  Diag(Name.getLocStart(),
4149  diag::ext_out_of_line_qualified_id_type_names_constructor)
4150  << Name.Identifier << 0 /*injected-class-name used as template name*/
4151  << 1 /*'template' keyword was used*/;
4152  }
4153  return TNK;
4154  }
4155  }
4156 
4157  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4158 
4159  switch (Name.getKind()) {
4161  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4162  Name.Identifier));
4164 
4166  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4168  return TNK_Function_template;
4169 
4171  llvm_unreachable("literal operator id cannot have a dependent scope");
4172 
4173  default:
4174  break;
4175  }
4176 
4177  Diag(Name.getLocStart(),
4178  diag::err_template_kw_refers_to_non_template)
4179  << GetNameFromUnqualifiedId(Name).getName()
4180  << Name.getSourceRange()
4181  << TemplateKWLoc;
4182  return TNK_Non_template;
4183 }
4184 
4186  TemplateArgumentLoc &AL,
4187  SmallVectorImpl<TemplateArgument> &Converted) {
4188  const TemplateArgument &Arg = AL.getArgument();
4189  QualType ArgType;
4190  TypeSourceInfo *TSI = nullptr;
4191 
4192  // Check template type parameter.
4193  switch(Arg.getKind()) {
4195  // C++ [temp.arg.type]p1:
4196  // A template-argument for a template-parameter which is a
4197  // type shall be a type-id.
4198  ArgType = Arg.getAsType();
4199  TSI = AL.getTypeSourceInfo();
4200  break;
4203  // We have a template type parameter but the template argument
4204  // is a template without any arguments.
4205  SourceRange SR = AL.getSourceRange();
4207  Diag(SR.getBegin(), diag::err_template_missing_args)
4208  << (int)getTemplateNameKindForDiagnostics(Name) << Name << SR;
4209  if (TemplateDecl *Decl = Name.getAsTemplateDecl())
4210  Diag(Decl->getLocation(), diag::note_template_decl_here);
4211 
4212  return true;
4213  }
4215  // We have a template type parameter but the template argument is an
4216  // expression; see if maybe it is missing the "typename" keyword.
4217  CXXScopeSpec SS;
4218  DeclarationNameInfo NameInfo;
4219 
4220  if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
4221  SS.Adopt(ArgExpr->getQualifierLoc());
4222  NameInfo = ArgExpr->getNameInfo();
4223  } else if (DependentScopeDeclRefExpr *ArgExpr =
4224  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4225  SS.Adopt(ArgExpr->getQualifierLoc());
4226  NameInfo = ArgExpr->getNameInfo();
4227  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4228  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4229  if (ArgExpr->isImplicitAccess()) {
4230  SS.Adopt(ArgExpr->getQualifierLoc());
4231  NameInfo = ArgExpr->getMemberNameInfo();
4232  }
4233  }
4234 
4235  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4236  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4237  LookupParsedName(Result, CurScope, &SS);
4238 
4239  if (Result.getAsSingle<TypeDecl>() ||
4240  Result.getResultKind() ==
4242  // Suggest that the user add 'typename' before the NNS.
4243  SourceLocation Loc = AL.getSourceRange().getBegin();
4244  Diag(Loc, getLangOpts().MSVCCompat
4245  ? diag::ext_ms_template_type_arg_missing_typename
4246  : diag::err_template_arg_must_be_type_suggest)
4247  << FixItHint::CreateInsertion(Loc, "typename ");
4248  Diag(Param->getLocation(), diag::note_template_param_here);
4249 
4250  // Recover by synthesizing a type using the location information that we
4251  // already have.
4252  ArgType =
4253  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4254  TypeLocBuilder TLB;
4255  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4256  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4257  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4258  TL.setNameLoc(NameInfo.getLoc());
4259  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4260 
4261  // Overwrite our input TemplateArgumentLoc so that we can recover
4262  // properly.
4263  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
4265 
4266  break;
4267  }
4268  }
4269  // fallthrough
4270  LLVM_FALLTHROUGH;
4271  }
4272  default: {
4273  // We have a template type parameter but the template argument
4274  // is not a type.
4275  SourceRange SR = AL.getSourceRange();
4276  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
4277  Diag(Param->getLocation(), diag::note_template_param_here);
4278 
4279  return true;
4280  }
4281  }
4282 
4283  if (CheckTemplateArgument(Param, TSI))
4284  return true;
4285 
4286  // Add the converted template type argument.
4287  ArgType = Context.getCanonicalType(ArgType);
4288 
4289  // Objective-C ARC:
4290  // If an explicitly-specified template argument type is a lifetime type
4291  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
4292  if (getLangOpts().ObjCAutoRefCount &&
4293  ArgType->isObjCLifetimeType() &&
4294  !ArgType.getObjCLifetime()) {
4295  Qualifiers Qs;
4297  ArgType = Context.getQualifiedType(ArgType, Qs);
4298  }
4299 
4300  Converted.push_back(TemplateArgument(ArgType));
4301  return false;
4302 }
4303 
4304 /// \brief Substitute template arguments into the default template argument for
4305 /// the given template type parameter.
4306 ///
4307 /// \param SemaRef the semantic analysis object for which we are performing
4308 /// the substitution.
4309 ///
4310 /// \param Template the template that we are synthesizing template arguments
4311 /// for.
4312 ///
4313 /// \param TemplateLoc the location of the template name that started the
4314 /// template-id we are checking.
4315 ///
4316 /// \param RAngleLoc the location of the right angle bracket ('>') that
4317 /// terminates the template-id.
4318 ///
4319 /// \param Param the template template parameter whose default we are
4320 /// substituting into.
4321 ///
4322 /// \param Converted the list of template arguments provided for template
4323 /// parameters that precede \p Param in the template parameter list.
4324 /// \returns the substituted template argument, or NULL if an error occurred.
4325 static TypeSourceInfo *
4327  TemplateDecl *Template,
4328  SourceLocation TemplateLoc,
4329  SourceLocation RAngleLoc,
4330  TemplateTypeParmDecl *Param,
4331  SmallVectorImpl<TemplateArgument> &Converted) {
4332  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
4333 
4334  // If the argument type is dependent, instantiate it now based
4335  // on the previously-computed template arguments.
4336  if (ArgType->getType()->isDependentType()) {
4337  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4338  Param, Template, Converted,
4339  SourceRange(TemplateLoc, RAngleLoc));
4340  if (Inst.isInvalid())
4341  return nullptr;
4342 
4343  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4344 
4345  // Only substitute for the innermost template argument list.
4346  MultiLevelTemplateArgumentList TemplateArgLists;
4347  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4348  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4349  TemplateArgLists.addOuterTemplateArguments(None);
4350 
4351  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4352  ArgType =
4353  SemaRef.SubstType(ArgType, TemplateArgLists,
4354  Param->getDefaultArgumentLoc(), Param->getDeclName());
4355  }
4356 
4357  return ArgType;
4358 }
4359 
4360 /// \brief Substitute template arguments into the default template argument for
4361 /// the given non-type template parameter.
4362 ///
4363 /// \param SemaRef the semantic analysis object for which we are performing
4364 /// the substitution.
4365 ///
4366 /// \param Template the template that we are synthesizing template arguments
4367 /// for.
4368 ///
4369 /// \param TemplateLoc the location of the template name that started the
4370 /// template-id we are checking.
4371 ///
4372 /// \param RAngleLoc the location of the right angle bracket ('>') that
4373 /// terminates the template-id.
4374 ///
4375 /// \param Param the non-type template parameter whose default we are
4376 /// substituting into.
4377 ///
4378 /// \param Converted the list of template arguments provided for template
4379 /// parameters that precede \p Param in the template parameter list.
4380 ///
4381 /// \returns the substituted template argument, or NULL if an error occurred.
4382 static ExprResult
4384  TemplateDecl *Template,
4385  SourceLocation TemplateLoc,
4386  SourceLocation RAngleLoc,
4387  NonTypeTemplateParmDecl *Param,
4388  SmallVectorImpl<TemplateArgument> &Converted) {
4389  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4390  Param, Template, Converted,
4391  SourceRange(TemplateLoc, RAngleLoc));
4392  if (Inst.isInvalid())
4393  return ExprError();
4394 
4395  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4396 
4397  // Only substitute for the innermost template argument list.
4398  MultiLevelTemplateArgumentList TemplateArgLists;
4399  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4400  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4401  TemplateArgLists.addOuterTemplateArguments(None);
4402 
4403  EnterExpressionEvaluationContext ConstantEvaluated(
4405  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
4406 }
4407 
4408 /// \brief Substitute template arguments into the default template argument for
4409 /// the given template template parameter.
4410 ///
4411 /// \param SemaRef the semantic analysis object for which we are performing
4412 /// the substitution.
4413 ///
4414 /// \param Template the template that we are synthesizing template arguments
4415 /// for.
4416 ///
4417 /// \param TemplateLoc the location of the template name that started the
4418 /// template-id we are checking.
4419 ///
4420 /// \param RAngleLoc the location of the right angle bracket ('>') that
4421 /// terminates the template-id.
4422 ///
4423 /// \param Param the template template parameter whose default we are
4424 /// substituting into.
4425 ///
4426 /// \param Converted the list of template arguments provided for template
4427 /// parameters that precede \p Param in the template parameter list.
4428 ///
4429 /// \param QualifierLoc Will be set to the nested-name-specifier (with
4430 /// source-location information) that precedes the template name.
4431 ///
4432 /// \returns the substituted template argument, or NULL if an error occurred.
4433 static TemplateName
4435  TemplateDecl *Template,
4436  SourceLocation TemplateLoc,
4437  SourceLocation RAngleLoc,
4438  TemplateTemplateParmDecl *Param,
4440  NestedNameSpecifierLoc &QualifierLoc) {
4442  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
4443  SourceRange(TemplateLoc, RAngleLoc));
4444  if (Inst.isInvalid())
4445  return TemplateName();
4446 
4447  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4448 
4449  // Only substitute for the innermost template argument list.
4450  MultiLevelTemplateArgumentList TemplateArgLists;
4451  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4452  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4453  TemplateArgLists.addOuterTemplateArguments(None);
4454 
4455  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4456  // Substitute into the nested-name-specifier first,
4457  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
4458  if (QualifierLoc) {
4459  QualifierLoc =
4460  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
4461  if (!QualifierLoc)
4462  return TemplateName();
4463  }
4464 
4465  return SemaRef.SubstTemplateName(
4466  QualifierLoc,
4469  TemplateArgLists);
4470 }
4471 
4472 /// \brief If the given template parameter has a default template
4473 /// argument, substitute into that default template argument and
4474 /// return the corresponding template argument.
4477  SourceLocation TemplateLoc,
4478  SourceLocation RAngleLoc,
4479  Decl *Param,
4481  &Converted,
4482  bool &HasDefaultArg) {
4483  HasDefaultArg = false;
4484 
4485  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
4486  if (!hasVisibleDefaultArgument(TypeParm))
4487  return TemplateArgumentLoc();
4488 
4489  HasDefaultArg = true;
4490  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
4491  TemplateLoc,
4492  RAngleLoc,
4493  TypeParm,
4494  Converted);
4495  if (DI)
4496  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
4497 
4498  return TemplateArgumentLoc();
4499  }
4500 
4501  if (NonTypeTemplateParmDecl *NonTypeParm
4502  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4503  if (!hasVisibleDefaultArgument(NonTypeParm))
4504  return TemplateArgumentLoc();
4505 
4506  HasDefaultArg = true;
4507  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
4508  TemplateLoc,
4509  RAngleLoc,
4510  NonTypeParm,
4511  Converted);
4512  if (Arg.isInvalid())
4513  return TemplateArgumentLoc();
4514 
4515  Expr *ArgE = Arg.getAs<Expr>();
4516  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
4517  }
4518 
4519  TemplateTemplateParmDecl *TempTempParm
4520  = cast<TemplateTemplateParmDecl>(Param);
4521  if (!hasVisibleDefaultArgument(TempTempParm))
4522  return TemplateArgumentLoc();
4523 
4524  HasDefaultArg = true;
4525  NestedNameSpecifierLoc QualifierLoc;
4526  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
4527  TemplateLoc,
4528  RAngleLoc,
4529  TempTempParm,
4530  Converted,
4531  QualifierLoc);
4532  if (TName.isNull())
4533  return TemplateArgumentLoc();
4534 
4535  return TemplateArgumentLoc(TemplateArgument(TName),
4536  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
4537  TempTempParm->getDefaultArgument().getTemplateNameLoc());
4538 }
4539 
4540 /// Convert a template-argument that we parsed as a type into a template, if
4541 /// possible. C++ permits injected-class-names to perform dual service as
4542 /// template template arguments and as template type arguments.
4544  // Extract and step over any surrounding nested-name-specifier.
4545  NestedNameSpecifierLoc QualLoc;
4546  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
4547  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
4548  return TemplateArgumentLoc();
4549 
4550  QualLoc = ETLoc.getQualifierLoc();
4551  TLoc = ETLoc.getNamedTypeLoc();
4552  }
4553 
4554  // If this type was written as an injected-class-name, it can be used as a
4555  // template template argument.
4556  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
4557  return TemplateArgumentLoc(InjLoc.getTypePtr()->getTemplateName(),
4558  QualLoc, InjLoc.getNameLoc());
4559 
4560  // If this type was written as an injected-class-name, it may have been
4561  // converted to a RecordType during instantiation. If the RecordType is
4562  // *not* wrapped in a TemplateSpecializationType and denotes a class
4563  // template specialization, it must have come from an injected-class-name.
4564  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
4565  if (auto *CTSD =
4566  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
4567  return TemplateArgumentLoc(TemplateName(CTSD->getSpecializedTemplate()),
4568  QualLoc, RecLoc.getNameLoc());
4569 
4570  return TemplateArgumentLoc();
4571 }
4572 
4573 /// \brief Check that the given template argument corresponds to the given
4574 /// template parameter.
4575 ///
4576 /// \param Param The template parameter against which the argument will be
4577 /// checked.
4578 ///
4579 /// \param Arg The template argument, which may be updated due to conversions.
4580 ///
4581 /// \param Template The template in which the template argument resides.
4582 ///
4583 /// \param TemplateLoc The location of the template name for the template
4584 /// whose argument list we're matching.
4585 ///
4586 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
4587 /// the template argument list.
4588 ///
4589 /// \param ArgumentPackIndex The index into the argument pack where this
4590 /// argument will be placed. Only valid if the parameter is a parameter pack.
4591 ///
4592 /// \param Converted The checked, converted argument will be added to the
4593 /// end of this small vector.
4594 ///
4595 /// \param CTAK Describes how we arrived at this particular template argument:
4596 /// explicitly written, deduced, etc.
4597 ///
4598 /// \returns true on error, false otherwise.
4600  TemplateArgumentLoc &Arg,
4601  NamedDecl *Template,
4602  SourceLocation TemplateLoc,
4603  SourceLocation RAngleLoc,
4604  unsigned ArgumentPackIndex,
4607  // Check template type parameters.
4608  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
4609  return CheckTemplateTypeArgument(TTP, Arg, Converted);
4610 
4611  // Check non-type template parameters.
4612  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4613  // Do substitution on the type of the non-type template parameter
4614  // with the template arguments we've seen thus far. But if the
4615  // template has a dependent context then we cannot substitute yet.
4616  QualType NTTPType = NTTP->getType();
4617  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
4618  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
4619 
4620  // FIXME: Do we need to substitute into parameters here if they're
4621  // instantiation-dependent but not dependent?
4622  if (NTTPType->isDependentType() &&
4623  !isa<TemplateTemplateParmDecl>(Template) &&
4624  !Template->getDeclContext()->isDependentContext()) {
4625  // Do substitution on the type of the non-type template parameter.
4626  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4627  NTTP, Converted,
4628  SourceRange(TemplateLoc, RAngleLoc));
4629  if (Inst.isInvalid())
4630  return true;
4631 
4633  Converted);
4634  NTTPType = SubstType(NTTPType,
4635  MultiLevelTemplateArgumentList(TemplateArgs),
4636  NTTP->getLocation(),
4637  NTTP->getDeclName());
4638  // If that worked, check the non-type template parameter type
4639  // for validity.
4640  if (!NTTPType.isNull())
4641  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
4642  NTTP->getLocation());
4643  if (NTTPType.isNull())
4644  return true;
4645  }
4646 
4647  switch (Arg.getArgument().getKind()) {
4649  llvm_unreachable("Should never see a NULL template argument here");
4650 
4652  TemplateArgument Result;
4653  ExprResult Res =
4654  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
4655  Result, CTAK);
4656  if (Res.isInvalid())
4657  return true;
4658 
4659  // If the resulting expression is new, then use it in place of the
4660  // old expression in the template argument.
4661  if (Res.get() != Arg.getArgument().getAsExpr()) {
4662  TemplateArgument TA(Res.get());
4663  Arg = TemplateArgumentLoc(TA, Res.get());
4664  }
4665 
4666  Converted.push_back(Result);
4667  break;
4668  }
4669 
4673  // We've already checked this template argument, so just copy
4674  // it to the list of converted arguments.
4675  Converted.push_back(Arg.getArgument());
4676  break;
4677 
4680  // We were given a template template argument. It may not be ill-formed;
4681  // see below.
4682  if (DependentTemplateName *DTN
4685  // We have a template argument such as \c T::template X, which we
4686  // parsed as a template template argument. However, since we now
4687  // know that we need a non-type template argument, convert this
4688  // template name into an expression.
4689 
4690  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
4691  Arg.getTemplateNameLoc());
4692 
4693  CXXScopeSpec SS;
4694  SS.Adopt(Arg.getTemplateQualifierLoc());
4695  // FIXME: the template-template arg was a DependentTemplateName,
4696  // so it was provided with a template keyword. However, its source
4697  // location is not stored in the template argument structure.
4698  SourceLocation TemplateKWLoc;
4700  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
4701  nullptr);
4702 
4703  // If we parsed the template argument as a pack expansion, create a
4704  // pack expansion expression.
4706  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
4707  if (E.isInvalid())
4708  return true;
4709  }
4710 
4711  TemplateArgument Result;
4712  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
4713  if (E.isInvalid())
4714  return true;
4715 
4716  Converted.push_back(Result);
4717  break;
4718  }
4719 
4720  // We have a template argument that actually does refer to a class
4721  // template, alias template, or template template parameter, and
4722  // therefore cannot be a non-type template argument.
4723  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
4724  << Arg.getSourceRange();
4725 
4726  Diag(Param->getLocation(), diag::note_template_param_here);
4727  return true;
4728 
4729  case TemplateArgument::Type: {
4730  // We have a non-type template parameter but the template
4731  // argument is a type.
4732 
4733  // C++ [temp.arg]p2:
4734  // In a template-argument, an ambiguity between a type-id and
4735  // an expression is resolved to a type-id, regardless of the
4736  // form of the corresponding template-parameter.
4737  //
4738  // We warn specifically about this case, since it can be rather
4739  // confusing for users.
4740  QualType T = Arg.getArgument().getAsType();
4741  SourceRange SR = Arg.getSourceRange();
4742  if (T->isFunctionType())
4743  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
4744  else
4745  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
4746  Diag(Param->getLocation(), diag::note_template_param_here);
4747  return true;
4748  }
4749 
4751  llvm_unreachable("Caller must expand template argument packs");
4752  }
4753 
4754  return false;
4755  }
4756 
4757 
4758  // Check template template parameters.
4759  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
4760 
4761  TemplateParameterList *Params = TempParm->getTemplateParameters();
4762  if (TempParm->isExpandedParameterPack())
4763  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
4764 
4765  // Substitute into the template parameter list of the template
4766  // template parameter, since previously-supplied template arguments
4767  // may appear within the template template parameter.
4768  //
4769  // FIXME: Skip this if the parameters aren't instantiation-dependent.
4770  {
4771  // Set up a template instantiation context.
4773  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4774  TempParm, Converted,
4775  SourceRange(TemplateLoc, RAngleLoc));
4776  if (Inst.isInvalid())
4777  return true;
4778 
4779  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4780  Params = SubstTemplateParams(Params, CurContext,
4781  MultiLevelTemplateArgumentList(TemplateArgs));
4782  if (!Params)
4783  return true;
4784  }
4785 
4786  // C++1z [temp.local]p1: (DR1004)
4787  // When [the injected-class-name] is used [...] as a template-argument for
4788  // a template template-parameter [...] it refers to the class template
4789  // itself.
4790  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
4792  Arg.getTypeSourceInfo()->getTypeLoc());
4793  if (!ConvertedArg.getArgument().isNull())
4794  Arg = ConvertedArg;
4795  }
4796 
4797  switch (Arg.getArgument().getKind()) {
4799  llvm_unreachable("Should never see a NULL template argument here");
4800 
4803  if (CheckTemplateTemplateArgument(Params, Arg))
4804  return true;
4805 
4806  Converted.push_back(Arg.getArgument());
4807  break;
4808 
4811  // We have a template template parameter but the template
4812  // argument does not refer to a template.
4813  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
4814  << getLangOpts().CPlusPlus11;
4815  return true;
4816 
4818  llvm_unreachable("Declaration argument with template template parameter");
4820  llvm_unreachable("Integral argument with template template parameter");
4822  llvm_unreachable("Null pointer argument with template template parameter");
4823 
4825  llvm_unreachable("Caller must expand template argument packs");
4826  }
4827 
4828  return false;
4829 }
4830 
4831 /// \brief Diagnose an arity mismatch in the
4832 static bool diagnoseArityMismatch(Sema &S, TemplateDecl *Template,
4833  SourceLocation TemplateLoc,
4834  TemplateArgumentListInfo &TemplateArgs) {
4835  TemplateParameterList *Params = Template->getTemplateParameters();
4836  unsigned NumParams = Params->size();
4837  unsigned NumArgs = TemplateArgs.size();
4838 
4839  SourceRange Range;
4840  if (NumArgs > NumParams)
4841  Range = SourceRange(TemplateArgs[NumParams].getLocation(),
4842  TemplateArgs.getRAngleLoc());
4843  S.Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
4844  << (NumArgs > NumParams)
4845  << (int)S.getTemplateNameKindForDiagnostics(TemplateName(Template))
4846  << Template << Range;
4847  S.Diag(Template->getLocation(), diag::note_template_decl_here)
4848  << Params->getSourceRange();
4849  return true;
4850 }
4851 
4852 /// \brief Check whether the template parameter is a pack expansion, and if so,
4853 /// determine the number of parameters produced by that expansion. For instance:
4854 ///
4855 /// \code
4856 /// template<typename ...Ts> struct A {
4857 /// template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
4858 /// };
4859 /// \endcode
4860 ///
4861 /// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
4862 /// is not a pack expansion, so returns an empty Optional.
4864  if (NonTypeTemplateParmDecl *NTTP
4865  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4866  if (NTTP->isExpandedParameterPack())
4867  return NTTP->getNumExpansionTypes();
4868  }
4869 
4870  if (TemplateTemplateParmDecl *TTP
4871  = dyn_cast<TemplateTemplateParmDecl>(Param)) {
4872  if (TTP->isExpandedParameterPack())
4873  return TTP->getNumExpansionTemplateParameters();
4874  }
4875 
4876  return None;
4877 }
4878 
4879 /// Diagnose a missing template argument.
4880 template<typename TemplateParmDecl>
4882  TemplateDecl *TD,
4883  const TemplateParmDecl *D,
4884  TemplateArgumentListInfo &Args) {
4885  // Dig out the most recent declaration of the template parameter; there may be
4886  // declarations of the template that are more recent than TD.
4887  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
4888  ->getTemplateParameters()
4889  ->getParam(D->getIndex()));
4890 
4891  // If there's a default argument that's not visible, diagnose that we're
4892  // missing a module import.
4894  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
4895  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
4896  D->getDefaultArgumentLoc(), Modules,
4898  /*Recover*/true);
4899  return true;
4900  }
4901 
4902  // FIXME: If there's a more recent default argument that *is* visible,
4903  // diagnose that it was declared too late.
4904 
4905  return diagnoseArityMismatch(S, TD, Loc, Args);
4906 }
4907 
4908 /// \brief Check that the given template argument list is well-formed
4909 /// for specializing the given template.
4911  TemplateDecl *Template, SourceLocation TemplateLoc,
4912  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
4914  bool UpdateArgsWithConversions) {
4915  // Make a copy of the template arguments for processing. Only make the
4916  // changes at the end when successful in matching the arguments to the
4917  // template.
4918  TemplateArgumentListInfo NewArgs = TemplateArgs;
4919 
4920  // Make sure we get the template parameter list from the most
4921  // recentdeclaration, since that is the only one that has is guaranteed to
4922  // have all the default template argument information.
4923  TemplateParameterList *Params =
4924  cast<TemplateDecl>(Template->getMostRecentDecl())
4925  ->getTemplateParameters();
4926 
4927  SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
4928 
4929  // C++ [temp.arg]p1:
4930  // [...] The type and form of each template-argument specified in
4931  // a template-id shall match the type and form specified for the
4932  // corresponding parameter declared by the template in its
4933  // template-parameter-list.
4934  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
4935  SmallVector<TemplateArgument, 2> ArgumentPack;
4936  unsigned ArgIdx = 0, NumArgs = NewArgs.size();
4937  LocalInstantiationScope InstScope(*this, true);
4938  for (TemplateParameterList::iterator Param = Params->begin(),
4939  ParamEnd = Params->end();
4940  Param != ParamEnd; /* increment in loop */) {
4941  // If we have an expanded parameter pack, make sure we don't have too
4942  // many arguments.
4943  if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
4944  if (*Expansions == ArgumentPack.size()) {
4945  // We're done with this parameter pack. Pack up its arguments and add
4946  // them to the list.
4947  Converted.push_back(
4948  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
4949  ArgumentPack.clear();
4950 
4951  // This argument is assigned to the next parameter.
4952  ++Param;
4953  continue;
4954  } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
4955  // Not enough arguments for this parameter pack.
4956  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
4957  << false
4958  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
4959  << Template;
4960  Diag(Template->getLocation(), diag::note_template_decl_here)
4961  << Params->getSourceRange();
4962  return true;
4963  }
4964  }
4965 
4966  if (ArgIdx < NumArgs) {
4967  // Check the template argument we were given.
4968  if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
4969  TemplateLoc, RAngleLoc,
4970  ArgumentPack.size(), Converted))
4971  return true;
4972 
4973  bool PackExpansionIntoNonPack =
4974  NewArgs[ArgIdx].getArgument().isPackExpansion() &&
4975  (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
4976  if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
4977  // Core issue 1430: we have a pack expansion as an argument to an
4978  // alias template, and it's not part of a parameter pack. This
4979  // can't be canonicalized, so reject it now.
4980  Diag(NewArgs[ArgIdx].getLocation(),
4981  diag::err_alias_template_expansion_into_fixed_list)
4982  << NewArgs[ArgIdx].getSourceRange();
4983  Diag((*Param)->getLocation(), diag::note_template_param_here);
4984  return true;
4985  }
4986 
4987  // We're now done with this argument.
4988  ++ArgIdx;
4989 
4990  if ((*Param)->isTemplateParameterPack()) {
4991  // The template parameter was a template parameter pack, so take the
4992  // deduced argument and place it on the argument pack. Note that we
4993  // stay on the same template parameter so that we can deduce more
4994  // arguments.
4995  ArgumentPack.push_back(Converted.pop_back_val());
4996  } else {
4997  // Move to the next template parameter.
4998  ++Param;
4999  }
5000 
5001  // If we just saw a pack expansion into a non-pack, then directly convert
5002  // the remaining arguments, because we don't know what parameters they'll
5003  // match up with.
5004  if (PackExpansionIntoNonPack) {
5005  if (!ArgumentPack.empty()) {
5006  // If we were part way through filling in an expanded parameter pack,
5007  // fall back to just producing individual arguments.
5008  Converted.insert(Converted.end(),
5009  ArgumentPack.begin(), ArgumentPack.end());
5010  ArgumentPack.clear();
5011  }
5012 
5013  while (ArgIdx < NumArgs) {
5014  Converted.push_back(NewArgs[ArgIdx].getArgument());
5015  ++ArgIdx;
5016  }
5017 
5018  return false;
5019  }
5020 
5021  continue;
5022  }
5023 
5024  // If we're checking a partial template argument list, we're done.
5025  if (PartialTemplateArgs) {
5026  if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
5027  Converted.push_back(
5028  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5029 
5030  return false;
5031  }
5032 
5033  // If we have a template parameter pack with no more corresponding
5034  // arguments, just break out now and we'll fill in the argument pack below.
5035  if ((*Param)->isTemplateParameterPack()) {
5036  assert(!getExpandedPackSize(*Param) &&
5037  "Should have dealt with this already");
5038 
5039  // A non-expanded parameter pack before the end of the parameter list
5040  // only occurs for an ill-formed template parameter list, unless we've
5041  // got a partial argument list for a function template, so just bail out.
5042  if (Param + 1 != ParamEnd)
5043  return true;
5044 
5045  Converted.push_back(
5046  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5047  ArgumentPack.clear();
5048 
5049  ++Param;
5050  continue;
5051  }
5052 
5053  // Check whether we have a default argument.
5054  TemplateArgumentLoc Arg;
5055 
5056  // Retrieve the default template argument from the template
5057  // parameter. For each kind of template parameter, we substitute the
5058  // template arguments provided thus far and any "outer" template arguments
5059  // (when the template parameter was part of a nested template) into
5060  // the default argument.
5061  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
5062  if (!hasVisibleDefaultArgument(TTP))
5063  return diagnoseMissingArgument(*this, TemplateLoc, Template, TTP,
5064  NewArgs);
5065 
5067  Template,
5068  TemplateLoc,
5069  RAngleLoc,
5070  TTP,
5071  Converted);
5072  if (!ArgType)
5073  return true;
5074 
5075  Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
5076  ArgType);
5077  } else if (NonTypeTemplateParmDecl *NTTP
5078  = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
5079  if (!hasVisibleDefaultArgument(NTTP))
5080  return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
5081  NewArgs);
5082 
5083  ExprResult E = SubstDefaultTemplateArgument(*this, Template,
5084  TemplateLoc,
5085  RAngleLoc,
5086  NTTP,
5087  Converted);
5088  if (E.isInvalid())
5089  return true;
5090 
5091  Expr *Ex = E.getAs<Expr>();
5092  Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
5093  } else {
5094  TemplateTemplateParmDecl *TempParm
5095  = cast<TemplateTemplateParmDecl>(*Param);
5096 
5097  if (!hasVisibleDefaultArgument(TempParm))
5098  return diagnoseMissingArgument(*this, TemplateLoc, Template, TempParm,
5099  NewArgs);
5100 
5101  NestedNameSpecifierLoc QualifierLoc;
5102  TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
5103  TemplateLoc,
5104  RAngleLoc,
5105  TempParm,
5106  Converted,
5107  QualifierLoc);
5108  if (Name.isNull())
5109  return true;
5110 
5111  Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
5112  TempParm->getDefaultArgument().getTemplateNameLoc());
5113  }
5114 
5115  // Introduce an instantiation record that describes where we are using
5116  // the default template argument. We're not actually instantiating a
5117  // template here, we just create this object to put a note into the
5118  // context stack.
5119  InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
5120  SourceRange(TemplateLoc, RAngleLoc));
5121  if (Inst.isInvalid())
5122  return true;
5123 
5124  // Check the default template argument.
5125  if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
5126  RAngleLoc, 0, Converted))
5127  return true;
5128 
5129  // Core issue 150 (assumed resolution): if this is a template template
5130  // parameter, keep track of the default template arguments from the
5131  // template definition.
5132  if (isTemplateTemplateParameter)
5133  NewArgs.addArgument(Arg);
5134 
5135  // Move to the next template parameter and argument.
5136  ++Param;
5137  ++ArgIdx;
5138  }
5139 
5140  // If we're performing a partial argument substitution, allow any trailing
5141  // pack expansions; they might be empty. This can happen even if
5142  // PartialTemplateArgs is false (the list of arguments is complete but
5143  // still dependent).
5144  if (ArgIdx < NumArgs && CurrentInstantiationScope &&
5145  CurrentInstantiationScope->getPartiallySubstitutedPack()) {
5146  while (ArgIdx < NumArgs && NewArgs[ArgIdx].getArgument().isPackExpansion())
5147  Converted.push_back(NewArgs[ArgIdx++].getArgument());
5148  }
5149 
5150  // If we have any leftover arguments, then there were too many arguments.
5151  // Complain and fail.
5152  if (ArgIdx < NumArgs)
5153  return diagnoseArityMismatch(*this, Template, TemplateLoc, NewArgs);
5154 
5155  // No problems found with the new argument list, propagate changes back
5156  // to caller.
5157  if (UpdateArgsWithConversions)
5158  TemplateArgs = std::move(NewArgs);
5159 
5160  return false;
5161 }
5162 
5163 namespace {
5164  class UnnamedLocalNoLinkageFinder
5165  : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
5166  {
5167  Sema &S;
5168  SourceRange SR;
5169 
5171 
5172  public:
5173  UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
5174 
5175  bool Visit(QualType T) {
5176  return T.isNull() ? false : inherited::Visit(T.getTypePtr());
5177  }
5178 
5179 #define TYPE(Class, Parent) \
5180  bool Visit##Class##Type(const Class##Type *);
5181 #define ABSTRACT_TYPE(Class, Parent) \
5182  bool Visit##Class##Type(const Class##Type *) { return false; }
5183 #define NON_CANONICAL_TYPE(Class, Parent) \
5184  bool Visit##Class##Type(const Class##Type *) { return false; }
5185 #include "clang/AST/TypeNodes.def"
5186 
5187  bool VisitTagDecl(const TagDecl *Tag);
5188  bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
5189  };
5190 } // end anonymous namespace
5191 
5192 bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
5193  return false;
5194 }
5195 
5196 bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
5197  return Visit(T->getElementType());
5198 }
5199 
5200 bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
5201  return Visit(T->getPointeeType());
5202 }
5203 
5204 bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
5205  const BlockPointerType* T) {
5206  return Visit(T->getPointeeType());
5207 }
5208 
5209 bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
5210  const LValueReferenceType* T) {
5211  return Visit(T->getPointeeType());
5212 }
5213 
5214 bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
5215  const RValueReferenceType* T) {
5216  return Visit(T->getPointeeType());
5217 }
5218 
5219 bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
5220  const MemberPointerType* T) {
5221  return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
5222 }
5223 
5224 bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
5225  const ConstantArrayType* T) {
5226  return Visit(T->getElementType());
5227 }
5228 
5229 bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
5230  const IncompleteArrayType* T) {
5231  return Visit(T->getElementType());
5232 }
5233 
5234 bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
5235  const VariableArrayType* T) {
5236  return Visit(T->getElementType());
5237 }
5238 
5239 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
5240  const DependentSizedArrayType* T) {
5241  return Visit(T->getElementType());
5242 }
5243 
5244 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
5245  const DependentSizedExtVectorType* T) {
5246  return Visit(T->getElementType());
5247 }
5248 
5249 bool UnnamedLocalNoLinkageFinder::VisitDependentAddressSpaceType(
5250  const DependentAddressSpaceType *T) {
5251  return Visit(T->getPointeeType());
5252 }
5253 
5254 bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
5255  return Visit(T->getElementType());
5256 }
5257 
5258 bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
5259  return Visit(T->getElementType());
5260 }
5261 
5262 bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
5263  const FunctionProtoType* T) {
5264  for (const auto &A : T->param_types()) {
5265  if (Visit(A))
5266  return true;
5267  }
5268 
5269  return Visit(T->getReturnType());
5270 }
5271 
5272 bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
5273  const FunctionNoProtoType* T) {
5274  return Visit(T->getReturnType());
5275 }
5276 
5277 bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
5278  const UnresolvedUsingType*) {
5279  return false;
5280 }
5281 
5282 bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
5283  return false;
5284 }
5285 
5286 bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
5287  return Visit(T->getUnderlyingType());
5288 }
5289 
5290 bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
5291  return false;
5292 }
5293 
5294 bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
5295  const UnaryTransformType*) {
5296  return false;
5297 }
5298 
5299 bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
5300  return Visit(T->getDeducedType());
5301 }
5302 
5303 bool UnnamedLocalNoLinkageFinder::VisitDeducedTemplateSpecializationType(
5305  return Visit(T->getDeducedType());
5306 }
5307 
5308 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
5309  return VisitTagDecl(T->getDecl());
5310 }
5311 
5312 bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
5313  return VisitTagDecl(T->getDecl());
5314 }
5315 
5316 bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
5317  const TemplateTypeParmType*) {
5318  return false;
5319 }
5320 
5321 bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
5323  return false;
5324 }
5325 
5326 bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
5327  const TemplateSpecializationType*) {
5328  return false;
5329 }
5330 
5331 bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
5332  const InjectedClassNameType* T) {
5333  return VisitTagDecl(T->getDecl());
5334 }
5335 
5336 bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
5337  const DependentNameType* T) {
5338  return VisitNestedNameSpecifier(T->getQualifier());
5339 }
5340 
5341 bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
5343  return VisitNestedNameSpecifier(T->getQualifier());
5344 }
5345 
5346 bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
5347  const PackExpansionType* T) {
5348  return Visit(T->getPattern());
5349 }
5350 
5351 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
5352  return false;
5353 }
5354 
5355 bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
5356  const ObjCInterfaceType *) {
5357  return false;
5358 }
5359 
5360 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
5361  const ObjCObjectPointerType *) {
5362  return false;
5363 }
5364 
5365 bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
5366  return Visit(T->getValueType());
5367 }
5368 
5369 bool UnnamedLocalNoLinkageFinder::VisitPipeType(const PipeType* T) {
5370  return false;
5371 }
5372 
5373 bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
5374  if (Tag->getDeclContext()->isFunctionOrMethod()) {
5375  S.Diag(SR.getBegin(),
5376  S.getLangOpts().CPlusPlus11 ?
5377  diag::warn_cxx98_compat_template_arg_local_type :
5378  diag::ext_template_arg_local_type)
5379  << S.Context.getTypeDeclType(Tag) << SR;
5380  return true;
5381  }
5382 
5383  if (!Tag->hasNameForLinkage()) {
5384  S.Diag(SR.getBegin(),
5385  S.getLangOpts().CPlusPlus11 ?
5386  diag::warn_cxx98_compat_template_arg_unnamed_type :
5387  diag::ext_template_arg_unnamed_type) << SR;
5388  S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
5389  return true;
5390  }
5391 
5392  return false;
5393 }
5394 
5395 bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
5396  NestedNameSpecifier *NNS) {
5397  if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
5398  return true;
5399 
5400  switch (NNS->getKind()) {
5406  return false;
5407 
5410  return Visit(QualType(NNS->getAsType(), 0));
5411  }
5412  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
5413 }
5414 
5415 /// \brief Check a template argument against its corresponding
5416 /// template type parameter.
5417 ///
5418 /// This routine implements the semantics of C++ [temp.arg.type]. It
5419 /// returns true if an error occurred, and false otherwise.
5421  TypeSourceInfo *ArgInfo) {
5422  assert(ArgInfo && "invalid TypeSourceInfo");
5423  QualType Arg = ArgInfo->getType();
5424  SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
5425 
5426  if (Arg->isVariablyModifiedType()) {
5427  return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
5428  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
5429  return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
5430  }
5431 
5432  // C++03 [temp.arg.type]p2:
5433  // A local type, a type with no linkage, an unnamed type or a type
5434  // compounded from any of these types shall not be used as a
5435  // template-argument for a template type-parameter.
5436  //
5437  // C++11 allows these, and even in C++03 we allow them as an extension with
5438  // a warning.
5439  if (LangOpts.CPlusPlus11 || Arg->hasUnnamedOrLocalType()) {
5440  UnnamedLocalNoLinkageFinder Finder(*this, SR);
5441  (void)Finder.Visit(Context.getCanonicalType(Arg));
5442  }
5443 
5444  return false;
5445 }
5446 
5451 };
5452 
5453 /// \brief Determine whether the given template argument is a null pointer
5454 /// value of the appropriate type.
5455 static NullPointerValueKind
5457  QualType ParamType, Expr *Arg,
5458  Decl *Entity = nullptr) {
5459  if (Arg->isValueDependent() || Arg->isTypeDependent())
5460  return NPV_NotNullPointer;
5461 
5462  // dllimport'd entities aren't constant but are available inside of template
5463  // arguments.
5464  if (Entity && Entity->hasAttr<DLLImportAttr>())
5465  return NPV_NotNullPointer;
5466 
5467  if (!S.isCompleteType(Arg->getExprLoc(), ParamType))
5468  llvm_unreachable(
5469  "Incomplete parameter type in isNullPointerValueTemplateArgument!");
5470 
5471  if (!S.getLangOpts().CPlusPlus11)
5472  return NPV_NotNullPointer;
5473 
5474  // Determine whether we have a constant expression.
5476  if (ArgRV.isInvalid())
5477  return NPV_Error;
5478  Arg = ArgRV.get();
5479 
5480  Expr::EvalResult EvalResult;
5482  EvalResult.Diag = &Notes;
5483  if (!Arg->EvaluateAsRValue(EvalResult, S.Context) ||
5484  EvalResult.HasSideEffects) {
5485  SourceLocation DiagLoc = Arg->getExprLoc();
5486 
5487  // If our only note is the usual "invalid subexpression" note, just point
5488  // the caret at its location rather than producing an essentially
5489  // redundant note.
5490  if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
5491  diag::note_invalid_subexpr_in_const_expr) {
5492  DiagLoc = Notes[0].first;
5493  Notes.clear();
5494  }
5495 
5496  S.Diag(DiagLoc, diag::err_template_arg_not_address_constant)
5497  << Arg->getType() << Arg->getSourceRange();
5498  for (unsigned I = 0, N = Notes.size(); I != N; ++I)
5499  S.Diag(Notes[I].first, Notes[I].second);
5500 
5501  S.Diag(Param->getLocation(), diag::note_template_param_here);
5502  return NPV_Error;
5503  }
5504 
5505  // C++11 [temp.arg.nontype]p1:
5506  // - an address constant expression of type std::nullptr_t
5507  if (Arg->getType()->isNullPtrType())
5508  return NPV_NullPointer;
5509 
5510  // - a constant expression that evaluates to a null pointer value (4.10); or
5511  // - a constant expression that evaluates to a null member pointer value
5512  // (4.11); or
5513  if ((EvalResult.Val.isLValue() && !EvalResult.Val.getLValueBase()) ||
5514  (EvalResult.Val.isMemberPointer() &&
5515  !EvalResult.Val.getMemberPointerDecl())) {
5516  // If our expression has an appropriate type, we've succeeded.
5517  bool ObjCLifetimeConversion;
5518  if (S.Context.hasSameUnqualifiedType(Arg->getType(), ParamType) ||
5519  S.IsQualificationConversion(Arg->getType(), ParamType, false,
5520  ObjCLifetimeConversion))
5521  return NPV_NullPointer;
5522 
5523  // The types didn't match, but we know we got a null pointer; complain,
5524  // then recover as if the types were correct.
5525  S.Diag(Arg->getExprLoc(), diag::err_template_arg_wrongtype_null_constant)
5526  << Arg->getType() << ParamType << Arg->getSourceRange();
5527  S.Diag(Param->getLocation(), diag::note_template_param_here);
5528  return NPV_NullPointer;
5529  }
5530 
5531  // If we don't have a null pointer value, but we do have a NULL pointer
5532  // constant, suggest a cast to the appropriate type.
5534  std::string Code = "static_cast<" + ParamType.getAsString() + ">(";
5535  S.Diag(Arg->getExprLoc(), diag::err_template_arg_untyped_null_constant)
5536  << ParamType << FixItHint::CreateInsertion(Arg->getLocStart(), Code)
5538  ")");
5539  S.Diag(Param->getLocation(), diag::note_template_param_here);
5540  return NPV_NullPointer;
5541  }
5542 
5543  // FIXME: If we ever want to support general, address-constant expressions
5544  // as non-type template arguments, we should return the ExprResult here to
5545  // be interpreted by the caller.
5546  return NPV_NotNullPointer;
5547 }
5548 
5549 /// \brief Checks whether the given template argument is compatible with its
5550 /// template parameter.
5552  Sema &S, NonTypeTemplateParmDecl *Param, QualType ParamType, Expr *ArgIn,
5553  Expr *Arg, QualType ArgType) {
5554  bool ObjCLifetimeConversion;
5555  if (ParamType->isPointerType() &&
5556  !ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType() &&
5557  S.IsQualificationConversion(ArgType, ParamType, false,
5558  ObjCLifetimeConversion)) {
5559  // For pointer-to-object types, qualification conversions are
5560  // permitted.
5561  } else {
5562  if (const ReferenceType *ParamRef = ParamType->getAs<ReferenceType>()) {
5563  if (!ParamRef->getPointeeType()->isFunctionType()) {
5564  // C++ [temp.arg.nontype]p5b3:
5565  // For a non-type template-parameter of type reference to
5566  // object, no conversions apply. The type referred to by the
5567  // reference may be more cv-qualified than the (otherwise
5568  // identical) type of the template- argument. The
5569  // template-parameter is bound directly to the
5570  // template-argument, which shall be an lvalue.
5571 
5572  // FIXME: Other qualifiers?
5573  unsigned ParamQuals = ParamRef->getPointeeType().getCVRQualifiers();
5574  unsigned ArgQuals = ArgType.getCVRQualifiers();
5575 
5576  if ((ParamQuals | ArgQuals) != ParamQuals) {
5577  S.Diag(Arg->getLocStart(),
5578  diag::err_template_arg_ref_bind_ignores_quals)
5579  << ParamType << Arg->getType() << Arg->getSourceRange();
5580  S.Diag(Param->getLocation(), diag::note_template_param_here);
5581  return true;
5582  }
5583  }
5584  }
5585 
5586  // At this point, the template argument refers to an object or
5587  // function with external linkage. We now need to check whether the
5588  // argument and parameter types are compatible.
5589  if (!S.Context.hasSameUnqualifiedType(ArgType,
5590  ParamType.getNonReferenceType())) {
5591  // We can't perform this conversion or binding.
5592  if (ParamType->isReferenceType())
5593  S.Diag(Arg->getLocStart(), diag::err_template_arg_no_ref_bind)
5594  << ParamType << ArgIn->getType() << Arg->getSourceRange();
5595  else
5596  S.Diag(Arg->getLocStart(), diag::err_template_arg_not_convertible)
5597  << ArgIn->getType() << ParamType << Arg->getSourceRange();
5598  S.Diag(Param->getLocation(), diag::note_template_param_here);
5599  return true;
5600  }
5601  }
5602 
5603  return false;
5604 }
5605 
5606 /// \brief Checks whether the given template argument is the address
5607 /// of an object or function according to C++ [temp.arg.nontype]p1.
5608 static bool
5610  NonTypeTemplateParmDecl *Param,
5611  QualType ParamType,
5612  Expr *ArgIn,
5613  TemplateArgument &Converted) {
5614  bool Invalid = false;
5615  Expr *Arg = ArgIn;
5616  QualType ArgType = Arg->getType();
5617 
5618  bool AddressTaken = false;
5619  SourceLocation AddrOpLoc;
5620  if (S.getLangOpts().MicrosoftExt) {
5621  // Microsoft Visual C++ strips all casts, allows an arbitrary number of
5622  // dereference and address-of operators.
5623  Arg = Arg->IgnoreParenCasts();
5624 
5625  bool ExtWarnMSTemplateArg = false;
5626  UnaryOperatorKind FirstOpKind;
5627  SourceLocation FirstOpLoc;
5628  while (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
5629  UnaryOperatorKind UnOpKind = UnOp->getOpcode();
5630  if (UnOpKind == UO_Deref)
5631  ExtWarnMSTemplateArg = true;
5632  if (UnOpKind == UO_AddrOf || UnOpKind == UO_Deref) {
5633  Arg = UnOp->getSubExpr()->IgnoreParenCasts();
5634  if (!AddrOpLoc.isValid()) {
5635  FirstOpKind = UnOpKind;
5636  FirstOpLoc = UnOp->getOperatorLoc();
5637  }
5638  } else
5639  break;
5640  }
5641  if (FirstOpLoc.isValid()) {
5642  if (ExtWarnMSTemplateArg)
5643  S.Diag(ArgIn->getLocStart(), diag::ext_ms_deref_template_argument)
5644  << ArgIn->getSourceRange();
5645 
5646  if (FirstOpKind == UO_AddrOf)
5647  AddressTaken = true;
5648  else if (Arg->getType()->isPointerType()) {
5649  // We cannot let pointers get dereferenced here, that is obviously not a
5650  // constant expression.
5651  assert(FirstOpKind == UO_Deref);
5652  S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
5653  << Arg->getSourceRange();
5654  }
5655  }
5656  } else {
5657  // See through any implicit casts we added to fix the type.
5658  Arg = Arg->IgnoreImpCasts();
5659 
5660  // C++ [temp.arg.nontype]p1:
5661  //
5662  // A template-argument for a non-type, non-template
5663  // template-parameter shall be one of: [...]
5664  //
5665  // -- the address of an object or function with external
5666  // linkage, including function templates and function
5667  // template-ids but excluding non-static class members,
5668  // expressed as & id-expression where the & is optional if
5669  // the name refers to a function or array, or if the
5670  // corresponding template-parameter is a reference; or
5671 
5672  // In C++98/03 mode, give an extension warning on any extra parentheses.
5673  // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
5674  bool ExtraParens = false;
5675  while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
5676  if (!Invalid && !ExtraParens) {
5677  S.Diag(Arg->getLocStart(),
5678  S.getLangOpts().CPlusPlus11
5679  ? diag::warn_cxx98_compat_template_arg_extra_parens
5680  : diag::ext_template_arg_extra_parens)
5681  << Arg->getSourceRange();
5682  ExtraParens = true;
5683  }
5684 
5685  Arg = Parens->getSubExpr();
5686  }
5687 
5688  while (SubstNonTypeTemplateParmExpr *subst =
5689  dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
5690  Arg = subst->getReplacement()->IgnoreImpCasts();
5691 
5692  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
5693  if (UnOp->getOpcode() == UO_AddrOf) {
5694  Arg = UnOp->getSubExpr();
5695  AddressTaken = true;
5696  AddrOpLoc = UnOp->getOperatorLoc();
5697  }
5698  }
5699 
5700  while (SubstNonTypeTemplateParmExpr *subst =
5701  dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
5702  Arg = subst->getReplacement()->IgnoreImpCasts();
5703  }
5704 
5705  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg);
5706  ValueDecl *Entity = DRE ? DRE->getDecl() : nullptr;
5707 
5708  // If our parameter has pointer type, check for a null template value.
5709  if (ParamType->isPointerType() || ParamType->isNullPtrType()) {
5710  switch (isNullPointerValueTemplateArgument(S, Param, ParamType, ArgIn,
5711  Entity)) {
5712  case NPV_NullPointer:
5713  S.Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
5714  Converted = TemplateArgument(S.Context.getCanonicalType(ParamType),
5715  /*isNullPtr=*/true);
5716  return false;
5717 
5718  case NPV_Error:
5719  return true;
5720 
5721  case NPV_NotNullPointer:
5722  break;
5723  }
5724  }
5725 
5726  // Stop checking the precise nature of the argument if it is value dependent,
5727  // it should be checked when instantiated.
5728  if (Arg->isValueDependent()) {
5729  Converted = TemplateArgument(ArgIn);
5730  return false;
5731  }
5732 
5733  if (isa<CXXUuidofExpr>(Arg)) {
5734  if (CheckTemplateArgumentIsCompatibleWithParameter(S, Param, ParamType,
5735  ArgIn, Arg, ArgType))
5736  return true;
5737 
5738  Converted = TemplateArgument(ArgIn);
5739  return false;
5740  }
5741 
5742  if (!DRE) {
5743  S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
5744  << Arg->getSourceRange();
5745  S.Diag(Param->getLocation(), diag::note_template_param_here);
5746  return true;
5747  }
5748 
5749  // Cannot refer to non-static data members
5750  if (isa<FieldDecl>(Entity) || isa<IndirectFieldDecl>(Entity)) {
5751  S.Diag(Arg->getLocStart(), diag::err_template_arg_field)
5752  << Entity << Arg->getSourceRange();
5753  S.Diag(Param->getLocation(), diag::note_template_param_here);
5754  return true;
5755  }
5756 
5757  // Cannot refer to non-static member functions
5758  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Entity)) {
5759  if (!Method->isStatic()) {
5760  S.