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SemaTemplate.cpp
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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //===----------------------------------------------------------------------===//
7 //
8 // This file implements semantic analysis for C++ templates.
9 //===----------------------------------------------------------------------===//
10 
11 #include "TreeTransform.h"
12 #include "clang/AST/ASTConsumer.h"
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/DeclFriend.h"
15 #include "clang/AST/DeclTemplate.h"
16 #include "clang/AST/Expr.h"
17 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/TypeVisitor.h"
20 #include "clang/Basic/Builtins.h"
23 #include "clang/Basic/Stack.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
26 #include "clang/Sema/Lookup.h"
27 #include "clang/Sema/Overload.h"
29 #include "clang/Sema/Scope.h"
31 #include "clang/Sema/Template.h"
33 #include "llvm/ADT/SmallBitVector.h"
34 #include "llvm/ADT/SmallString.h"
35 #include "llvm/ADT/StringExtras.h"
36 
37 #include <iterator>
38 using namespace clang;
39 using namespace sema;
40 
41 // Exported for use by Parser.
44  unsigned N) {
45  if (!N) return SourceRange();
46  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
47 }
48 
49 /// \brief Determine whether the declaration found is acceptable as the name
50 /// of a template and, if so, return that template declaration. Otherwise,
51 /// returns null.
52 ///
53 /// Note that this may return an UnresolvedUsingValueDecl if AllowDependent
54 /// is true. In all other cases it will return a TemplateDecl (or null).
56  bool AllowFunctionTemplates,
57  bool AllowDependent) {
58  D = D->getUnderlyingDecl();
59 
60  if (isa<TemplateDecl>(D)) {
61  if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
62  return nullptr;
63 
64  return D;
65  }
66 
67  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
68  // C++ [temp.local]p1:
69  // Like normal (non-template) classes, class templates have an
70  // injected-class-name (Clause 9). The injected-class-name
71  // can be used with or without a template-argument-list. When
72  // it is used without a template-argument-list, it is
73  // equivalent to the injected-class-name followed by the
74  // template-parameters of the class template enclosed in
75  // <>. When it is used with a template-argument-list, it
76  // refers to the specified class template specialization,
77  // which could be the current specialization or another
78  // specialization.
79  if (Record->isInjectedClassName()) {
80  Record = cast<CXXRecordDecl>(Record->getDeclContext());
81  if (Record->getDescribedClassTemplate())
82  return Record->getDescribedClassTemplate();
83 
85  = dyn_cast<ClassTemplateSpecializationDecl>(Record))
86  return Spec->getSpecializedTemplate();
87  }
88 
89  return nullptr;
90  }
91 
92  // 'using Dependent::foo;' can resolve to a template name.
93  // 'using typename Dependent::foo;' cannot (not even if 'foo' is an
94  // injected-class-name).
95  if (AllowDependent && isa<UnresolvedUsingValueDecl>(D))
96  return D;
97 
98  return nullptr;
99 }
100 
102  bool AllowFunctionTemplates,
103  bool AllowDependent) {
104  LookupResult::Filter filter = R.makeFilter();
105  while (filter.hasNext()) {
106  NamedDecl *Orig = filter.next();
107  if (!getAsTemplateNameDecl(Orig, AllowFunctionTemplates, AllowDependent))
108  filter.erase();
109  }
110  filter.done();
111 }
112 
114  bool AllowFunctionTemplates,
115  bool AllowDependent,
116  bool AllowNonTemplateFunctions) {
117  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
118  if (getAsTemplateNameDecl(*I, AllowFunctionTemplates, AllowDependent))
119  return true;
120  if (AllowNonTemplateFunctions &&
121  isa<FunctionDecl>((*I)->getUnderlyingDecl()))
122  return true;
123  }
124 
125  return false;
126 }
127 
129  CXXScopeSpec &SS,
130  bool hasTemplateKeyword,
131  const UnqualifiedId &Name,
132  ParsedType ObjectTypePtr,
133  bool EnteringContext,
134  TemplateTy &TemplateResult,
135  bool &MemberOfUnknownSpecialization) {
136  assert(getLangOpts().CPlusPlus && "No template names in C!");
137 
138  DeclarationName TName;
139  MemberOfUnknownSpecialization = false;
140 
141  switch (Name.getKind()) {
143  TName = DeclarationName(Name.Identifier);
144  break;
145 
147  TName = Context.DeclarationNames.getCXXOperatorName(
149  break;
150 
153  break;
154 
155  default:
156  return TNK_Non_template;
157  }
158 
159  QualType ObjectType = ObjectTypePtr.get();
160 
161  AssumedTemplateKind AssumedTemplate;
162  LookupResult R(*this, TName, Name.getBeginLoc(), LookupOrdinaryName);
163  if (LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
164  MemberOfUnknownSpecialization, SourceLocation(),
165  &AssumedTemplate))
166  return TNK_Non_template;
167 
168  if (AssumedTemplate != AssumedTemplateKind::None) {
169  TemplateResult = TemplateTy::make(Context.getAssumedTemplateName(TName));
170  // Let the parser know whether we found nothing or found functions; if we
171  // found nothing, we want to more carefully check whether this is actually
172  // a function template name versus some other kind of undeclared identifier.
173  return AssumedTemplate == AssumedTemplateKind::FoundNothing
176  }
177 
178  if (R.empty())
179  return TNK_Non_template;
180 
181  NamedDecl *D = nullptr;
182  if (R.isAmbiguous()) {
183  // If we got an ambiguity involving a non-function template, treat this
184  // as a template name, and pick an arbitrary template for error recovery.
185  bool AnyFunctionTemplates = false;
186  for (NamedDecl *FoundD : R) {
187  if (NamedDecl *FoundTemplate = getAsTemplateNameDecl(FoundD)) {
188  if (isa<FunctionTemplateDecl>(FoundTemplate))
189  AnyFunctionTemplates = true;
190  else {
191  D = FoundTemplate;
192  break;
193  }
194  }
195  }
196 
197  // If we didn't find any templates at all, this isn't a template name.
198  // Leave the ambiguity for a later lookup to diagnose.
199  if (!D && !AnyFunctionTemplates) {
200  R.suppressDiagnostics();
201  return TNK_Non_template;
202  }
203 
204  // If the only templates were function templates, filter out the rest.
205  // We'll diagnose the ambiguity later.
206  if (!D)
207  FilterAcceptableTemplateNames(R);
208  }
209 
210  // At this point, we have either picked a single template name declaration D
211  // or we have a non-empty set of results R containing either one template name
212  // declaration or a set of function templates.
213 
214  TemplateName Template;
215  TemplateNameKind TemplateKind;
216 
217  unsigned ResultCount = R.end() - R.begin();
218  if (!D && ResultCount > 1) {
219  // We assume that we'll preserve the qualifier from a function
220  // template name in other ways.
221  Template = Context.getOverloadedTemplateName(R.begin(), R.end());
222  TemplateKind = TNK_Function_template;
223 
224  // We'll do this lookup again later.
225  R.suppressDiagnostics();
226  } else {
227  if (!D) {
228  D = getAsTemplateNameDecl(*R.begin());
229  assert(D && "unambiguous result is not a template name");
230  }
231 
232  if (isa<UnresolvedUsingValueDecl>(D)) {
233  // We don't yet know whether this is a template-name or not.
234  MemberOfUnknownSpecialization = true;
235  return TNK_Non_template;
236  }
237 
238  TemplateDecl *TD = cast<TemplateDecl>(D);
239 
240  if (SS.isSet() && !SS.isInvalid()) {
241  NestedNameSpecifier *Qualifier = SS.getScopeRep();
242  Template = Context.getQualifiedTemplateName(Qualifier,
243  hasTemplateKeyword, TD);
244  } else {
245  Template = TemplateName(TD);
246  }
247 
248  if (isa<FunctionTemplateDecl>(TD)) {
249  TemplateKind = TNK_Function_template;
250 
251  // We'll do this lookup again later.
252  R.suppressDiagnostics();
253  } else {
254  assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
255  isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
256  isa<BuiltinTemplateDecl>(TD) || isa<ConceptDecl>(TD));
257  TemplateKind =
258  isa<VarTemplateDecl>(TD) ? TNK_Var_template :
259  isa<ConceptDecl>(TD) ? TNK_Concept_template :
261  }
262  }
263 
264  TemplateResult = TemplateTy::make(Template);
265  return TemplateKind;
266 }
267 
269  SourceLocation NameLoc,
270  ParsedTemplateTy *Template) {
271  CXXScopeSpec SS;
272  bool MemberOfUnknownSpecialization = false;
273 
274  // We could use redeclaration lookup here, but we don't need to: the
275  // syntactic form of a deduction guide is enough to identify it even
276  // if we can't look up the template name at all.
277  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
278  if (LookupTemplateName(R, S, SS, /*ObjectType*/ QualType(),
279  /*EnteringContext*/ false,
280  MemberOfUnknownSpecialization))
281  return false;
282 
283  if (R.empty()) return false;
284  if (R.isAmbiguous()) {
285  // FIXME: Diagnose an ambiguity if we find at least one template.
287  return false;
288  }
289 
290  // We only treat template-names that name type templates as valid deduction
291  // guide names.
293  if (!TD || !getAsTypeTemplateDecl(TD))
294  return false;
295 
296  if (Template)
297  *Template = TemplateTy::make(TemplateName(TD));
298  return true;
299 }
300 
302  SourceLocation IILoc,
303  Scope *S,
304  const CXXScopeSpec *SS,
305  TemplateTy &SuggestedTemplate,
306  TemplateNameKind &SuggestedKind) {
307  // We can't recover unless there's a dependent scope specifier preceding the
308  // template name.
309  // FIXME: Typo correction?
310  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
311  computeDeclContext(*SS))
312  return false;
313 
314  // The code is missing a 'template' keyword prior to the dependent template
315  // name.
317  Diag(IILoc, diag::err_template_kw_missing)
318  << Qualifier << II.getName()
319  << FixItHint::CreateInsertion(IILoc, "template ");
320  SuggestedTemplate
321  = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
322  SuggestedKind = TNK_Dependent_template_name;
323  return true;
324 }
325 
327  Scope *S, CXXScopeSpec &SS,
328  QualType ObjectType,
329  bool EnteringContext,
330  bool &MemberOfUnknownSpecialization,
331  SourceLocation TemplateKWLoc,
332  AssumedTemplateKind *ATK) {
333  if (ATK)
335 
336  Found.setTemplateNameLookup(true);
337 
338  // Determine where to perform name lookup
339  MemberOfUnknownSpecialization = false;
340  DeclContext *LookupCtx = nullptr;
341  bool IsDependent = false;
342  if (!ObjectType.isNull()) {
343  // This nested-name-specifier occurs in a member access expression, e.g.,
344  // x->B::f, and we are looking into the type of the object.
345  assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
346  LookupCtx = computeDeclContext(ObjectType);
347  IsDependent = !LookupCtx && ObjectType->isDependentType();
348  assert((IsDependent || !ObjectType->isIncompleteType() ||
349  ObjectType->castAs<TagType>()->isBeingDefined()) &&
350  "Caller should have completed object type");
351 
352  // Template names cannot appear inside an Objective-C class or object type
353  // or a vector type.
354  //
355  // FIXME: This is wrong. For example:
356  //
357  // template<typename T> using Vec = T __attribute__((ext_vector_type(4)));
358  // Vec<int> vi;
359  // vi.Vec<int>::~Vec<int>();
360  //
361  // ... should be accepted but we will not treat 'Vec' as a template name
362  // here. The right thing to do would be to check if the name is a valid
363  // vector component name, and look up a template name if not. And similarly
364  // for lookups into Objective-C class and object types, where the same
365  // problem can arise.
366  if (ObjectType->isObjCObjectOrInterfaceType() ||
367  ObjectType->isVectorType()) {
368  Found.clear();
369  return false;
370  }
371  } else if (SS.isSet()) {
372  // This nested-name-specifier occurs after another nested-name-specifier,
373  // so long into the context associated with the prior nested-name-specifier.
374  LookupCtx = computeDeclContext(SS, EnteringContext);
375  IsDependent = !LookupCtx;
376 
377  // The declaration context must be complete.
378  if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
379  return true;
380  }
381 
382  bool ObjectTypeSearchedInScope = false;
383  bool AllowFunctionTemplatesInLookup = true;
384  if (LookupCtx) {
385  // Perform "qualified" name lookup into the declaration context we
386  // computed, which is either the type of the base of a member access
387  // expression or the declaration context associated with a prior
388  // nested-name-specifier.
389  LookupQualifiedName(Found, LookupCtx);
390 
391  // FIXME: The C++ standard does not clearly specify what happens in the
392  // case where the object type is dependent, and implementations vary. In
393  // Clang, we treat a name after a . or -> as a template-name if lookup
394  // finds a non-dependent member or member of the current instantiation that
395  // is a type template, or finds no such members and lookup in the context
396  // of the postfix-expression finds a type template. In the latter case, the
397  // name is nonetheless dependent, and we may resolve it to a member of an
398  // unknown specialization when we come to instantiate the template.
399  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
400  }
401 
402  if (!SS.isSet() && (ObjectType.isNull() || Found.empty())) {
403  // C++ [basic.lookup.classref]p1:
404  // In a class member access expression (5.2.5), if the . or -> token is
405  // immediately followed by an identifier followed by a <, the
406  // identifier must be looked up to determine whether the < is the
407  // beginning of a template argument list (14.2) or a less-than operator.
408  // The identifier is first looked up in the class of the object
409  // expression. If the identifier is not found, it is then looked up in
410  // the context of the entire postfix-expression and shall name a class
411  // template.
412  if (S)
413  LookupName(Found, S);
414 
415  if (!ObjectType.isNull()) {
416  // FIXME: We should filter out all non-type templates here, particularly
417  // variable templates and concepts. But the exclusion of alias templates
418  // and template template parameters is a wording defect.
419  AllowFunctionTemplatesInLookup = false;
420  ObjectTypeSearchedInScope = true;
421  }
422 
423  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
424  }
425 
426  if (Found.isAmbiguous())
427  return false;
428 
429  if (ATK && !SS.isSet() && ObjectType.isNull() && TemplateKWLoc.isInvalid()) {
430  // C++2a [temp.names]p2:
431  // A name is also considered to refer to a template if it is an
432  // unqualified-id followed by a < and name lookup finds either one or more
433  // functions or finds nothing.
434  //
435  // To keep our behavior consistent, we apply the "finds nothing" part in
436  // all language modes, and diagnose the empty lookup in ActOnCallExpr if we
437  // successfully form a call to an undeclared template-id.
438  bool AllFunctions =
439  getLangOpts().CPlusPlus2a &&
440  std::all_of(Found.begin(), Found.end(), [](NamedDecl *ND) {
441  return isa<FunctionDecl>(ND->getUnderlyingDecl());
442  });
443  if (AllFunctions || (Found.empty() && !IsDependent)) {
444  // If lookup found any functions, or if this is a name that can only be
445  // used for a function, then strongly assume this is a function
446  // template-id.
447  *ATK = (Found.empty() && Found.getLookupName().isIdentifier())
448  ? AssumedTemplateKind::FoundNothing
449  : AssumedTemplateKind::FoundFunctions;
450  Found.clear();
451  return false;
452  }
453  }
454 
455  if (Found.empty() && !IsDependent) {
456  // If we did not find any names, attempt to correct any typos.
457  DeclarationName Name = Found.getLookupName();
458  Found.clear();
459  // Simple filter callback that, for keywords, only accepts the C++ *_cast
460  DefaultFilterCCC FilterCCC{};
461  FilterCCC.WantTypeSpecifiers = false;
462  FilterCCC.WantExpressionKeywords = false;
463  FilterCCC.WantRemainingKeywords = false;
464  FilterCCC.WantCXXNamedCasts = true;
465  if (TypoCorrection Corrected =
466  CorrectTypo(Found.getLookupNameInfo(), Found.getLookupKind(), S,
467  &SS, FilterCCC, CTK_ErrorRecovery, LookupCtx)) {
468  if (auto *ND = Corrected.getFoundDecl())
469  Found.addDecl(ND);
470  FilterAcceptableTemplateNames(Found);
471  if (Found.isAmbiguous()) {
472  Found.clear();
473  } else if (!Found.empty()) {
474  Found.setLookupName(Corrected.getCorrection());
475  if (LookupCtx) {
476  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
477  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
478  Name.getAsString() == CorrectedStr;
479  diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
480  << Name << LookupCtx << DroppedSpecifier
481  << SS.getRange());
482  } else {
483  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
484  }
485  }
486  }
487  }
488 
489  NamedDecl *ExampleLookupResult =
490  Found.empty() ? nullptr : Found.getRepresentativeDecl();
491  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
492  if (Found.empty()) {
493  if (IsDependent) {
494  MemberOfUnknownSpecialization = true;
495  return false;
496  }
497 
498  // If a 'template' keyword was used, a lookup that finds only non-template
499  // names is an error.
500  if (ExampleLookupResult && TemplateKWLoc.isValid()) {
501  Diag(Found.getNameLoc(), diag::err_template_kw_refers_to_non_template)
502  << Found.getLookupName() << SS.getRange();
503  Diag(ExampleLookupResult->getUnderlyingDecl()->getLocation(),
504  diag::note_template_kw_refers_to_non_template)
505  << Found.getLookupName();
506  return true;
507  }
508 
509  return false;
510  }
511 
512  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
513  !getLangOpts().CPlusPlus11) {
514  // C++03 [basic.lookup.classref]p1:
515  // [...] If the lookup in the class of the object expression finds a
516  // template, the name is also looked up in the context of the entire
517  // postfix-expression and [...]
518  //
519  // Note: C++11 does not perform this second lookup.
520  LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
521  LookupOrdinaryName);
522  FoundOuter.setTemplateNameLookup(true);
523  LookupName(FoundOuter, S);
524  // FIXME: We silently accept an ambiguous lookup here, in violation of
525  // [basic.lookup]/1.
526  FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
527 
528  NamedDecl *OuterTemplate;
529  if (FoundOuter.empty()) {
530  // - if the name is not found, the name found in the class of the
531  // object expression is used, otherwise
532  } else if (FoundOuter.isAmbiguous() || !FoundOuter.isSingleResult() ||
533  !(OuterTemplate =
534  getAsTemplateNameDecl(FoundOuter.getFoundDecl()))) {
535  // - if the name is found in the context of the entire
536  // postfix-expression and does not name a class template, the name
537  // found in the class of the object expression is used, otherwise
538  FoundOuter.clear();
539  } else if (!Found.isSuppressingDiagnostics()) {
540  // - if the name found is a class template, it must refer to the same
541  // entity as the one found in the class of the object expression,
542  // otherwise the program is ill-formed.
543  if (!Found.isSingleResult() ||
544  getAsTemplateNameDecl(Found.getFoundDecl())->getCanonicalDecl() !=
545  OuterTemplate->getCanonicalDecl()) {
546  Diag(Found.getNameLoc(),
547  diag::ext_nested_name_member_ref_lookup_ambiguous)
548  << Found.getLookupName()
549  << ObjectType;
551  diag::note_ambig_member_ref_object_type)
552  << ObjectType;
553  Diag(FoundOuter.getFoundDecl()->getLocation(),
554  diag::note_ambig_member_ref_scope);
555 
556  // Recover by taking the template that we found in the object
557  // expression's type.
558  }
559  }
560  }
561 
562  return false;
563 }
564 
566  SourceLocation Less,
567  SourceLocation Greater) {
568  if (TemplateName.isInvalid())
569  return;
570 
571  DeclarationNameInfo NameInfo;
572  CXXScopeSpec SS;
573  LookupNameKind LookupKind;
574 
575  DeclContext *LookupCtx = nullptr;
576  NamedDecl *Found = nullptr;
577  bool MissingTemplateKeyword = false;
578 
579  // Figure out what name we looked up.
580  if (auto *DRE = dyn_cast<DeclRefExpr>(TemplateName.get())) {
581  NameInfo = DRE->getNameInfo();
582  SS.Adopt(DRE->getQualifierLoc());
583  LookupKind = LookupOrdinaryName;
584  Found = DRE->getFoundDecl();
585  } else if (auto *ME = dyn_cast<MemberExpr>(TemplateName.get())) {
586  NameInfo = ME->getMemberNameInfo();
587  SS.Adopt(ME->getQualifierLoc());
588  LookupKind = LookupMemberName;
589  LookupCtx = ME->getBase()->getType()->getAsCXXRecordDecl();
590  Found = ME->getMemberDecl();
591  } else if (auto *DSDRE =
592  dyn_cast<DependentScopeDeclRefExpr>(TemplateName.get())) {
593  NameInfo = DSDRE->getNameInfo();
594  SS.Adopt(DSDRE->getQualifierLoc());
595  MissingTemplateKeyword = true;
596  } else if (auto *DSME =
597  dyn_cast<CXXDependentScopeMemberExpr>(TemplateName.get())) {
598  NameInfo = DSME->getMemberNameInfo();
599  SS.Adopt(DSME->getQualifierLoc());
600  MissingTemplateKeyword = true;
601  } else {
602  llvm_unreachable("unexpected kind of potential template name");
603  }
604 
605  // If this is a dependent-scope lookup, diagnose that the 'template' keyword
606  // was missing.
607  if (MissingTemplateKeyword) {
608  Diag(NameInfo.getBeginLoc(), diag::err_template_kw_missing)
609  << "" << NameInfo.getName().getAsString() << SourceRange(Less, Greater);
610  return;
611  }
612 
613  // Try to correct the name by looking for templates and C++ named casts.
614  struct TemplateCandidateFilter : CorrectionCandidateCallback {
615  Sema &S;
616  TemplateCandidateFilter(Sema &S) : S(S) {
617  WantTypeSpecifiers = false;
618  WantExpressionKeywords = false;
619  WantRemainingKeywords = false;
620  WantCXXNamedCasts = true;
621  };
622  bool ValidateCandidate(const TypoCorrection &Candidate) override {
623  if (auto *ND = Candidate.getCorrectionDecl())
624  return S.getAsTemplateNameDecl(ND);
625  return Candidate.isKeyword();
626  }
627 
628  std::unique_ptr<CorrectionCandidateCallback> clone() override {
629  return std::make_unique<TemplateCandidateFilter>(*this);
630  }
631  };
632 
633  DeclarationName Name = NameInfo.getName();
634  TemplateCandidateFilter CCC(*this);
635  if (TypoCorrection Corrected = CorrectTypo(NameInfo, LookupKind, S, &SS, CCC,
636  CTK_ErrorRecovery, LookupCtx)) {
637  auto *ND = Corrected.getFoundDecl();
638  if (ND)
639  ND = getAsTemplateNameDecl(ND);
640  if (ND || Corrected.isKeyword()) {
641  if (LookupCtx) {
642  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
643  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
644  Name.getAsString() == CorrectedStr;
645  diagnoseTypo(Corrected,
646  PDiag(diag::err_non_template_in_member_template_id_suggest)
647  << Name << LookupCtx << DroppedSpecifier
648  << SS.getRange(), false);
649  } else {
650  diagnoseTypo(Corrected,
651  PDiag(diag::err_non_template_in_template_id_suggest)
652  << Name, false);
653  }
654  if (Found)
655  Diag(Found->getLocation(),
656  diag::note_non_template_in_template_id_found);
657  return;
658  }
659  }
660 
661  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
662  << Name << SourceRange(Less, Greater);
663  if (Found)
664  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
665 }
666 
667 /// ActOnDependentIdExpression - Handle a dependent id-expression that
668 /// was just parsed. This is only possible with an explicit scope
669 /// specifier naming a dependent type.
672  SourceLocation TemplateKWLoc,
673  const DeclarationNameInfo &NameInfo,
674  bool isAddressOfOperand,
675  const TemplateArgumentListInfo *TemplateArgs) {
676  DeclContext *DC = getFunctionLevelDeclContext();
677 
678  // C++11 [expr.prim.general]p12:
679  // An id-expression that denotes a non-static data member or non-static
680  // member function of a class can only be used:
681  // (...)
682  // - if that id-expression denotes a non-static data member and it
683  // appears in an unevaluated operand.
684  //
685  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
686  // CXXDependentScopeMemberExpr. The former can instantiate to either
687  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
688  // always a MemberExpr.
689  bool MightBeCxx11UnevalField =
690  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
691 
692  // Check if the nested name specifier is an enum type.
693  bool IsEnum = false;
694  if (NestedNameSpecifier *NNS = SS.getScopeRep())
695  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
696 
697  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
698  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
699  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType();
700 
701  // Since the 'this' expression is synthesized, we don't need to
702  // perform the double-lookup check.
703  NamedDecl *FirstQualifierInScope = nullptr;
704 
706  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
707  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
708  FirstQualifierInScope, NameInfo, TemplateArgs);
709  }
710 
711  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
712 }
713 
716  SourceLocation TemplateKWLoc,
717  const DeclarationNameInfo &NameInfo,
718  const TemplateArgumentListInfo *TemplateArgs) {
719  // DependentScopeDeclRefExpr::Create requires a valid QualifierLoc
720  NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
721  if (!QualifierLoc)
722  return ExprError();
723 
725  Context, QualifierLoc, TemplateKWLoc, NameInfo, TemplateArgs);
726 }
727 
728 
729 /// Determine whether we would be unable to instantiate this template (because
730 /// it either has no definition, or is in the process of being instantiated).
732  NamedDecl *Instantiation,
733  bool InstantiatedFromMember,
734  const NamedDecl *Pattern,
735  const NamedDecl *PatternDef,
737  bool Complain /*= true*/) {
738  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
739  isa<VarDecl>(Instantiation));
740 
741  bool IsEntityBeingDefined = false;
742  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
743  IsEntityBeingDefined = TD->isBeingDefined();
744 
745  if (PatternDef && !IsEntityBeingDefined) {
746  NamedDecl *SuggestedDef = nullptr;
747  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
748  /*OnlyNeedComplete*/false)) {
749  // If we're allowed to diagnose this and recover, do so.
750  bool Recover = Complain && !isSFINAEContext();
751  if (Complain)
752  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
754  return !Recover;
755  }
756  return false;
757  }
758 
759  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
760  return true;
761 
763  QualType InstantiationTy;
764  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
765  InstantiationTy = Context.getTypeDeclType(TD);
766  if (PatternDef) {
767  Diag(PointOfInstantiation,
768  diag::err_template_instantiate_within_definition)
769  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
770  << InstantiationTy;
771  // Not much point in noting the template declaration here, since
772  // we're lexically inside it.
773  Instantiation->setInvalidDecl();
774  } else if (InstantiatedFromMember) {
775  if (isa<FunctionDecl>(Instantiation)) {
776  Diag(PointOfInstantiation,
777  diag::err_explicit_instantiation_undefined_member)
778  << /*member function*/ 1 << Instantiation->getDeclName()
779  << Instantiation->getDeclContext();
780  Note = diag::note_explicit_instantiation_here;
781  } else {
782  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
783  Diag(PointOfInstantiation,
784  diag::err_implicit_instantiate_member_undefined)
785  << InstantiationTy;
786  Note = diag::note_member_declared_at;
787  }
788  } else {
789  if (isa<FunctionDecl>(Instantiation)) {
790  Diag(PointOfInstantiation,
791  diag::err_explicit_instantiation_undefined_func_template)
792  << Pattern;
793  Note = diag::note_explicit_instantiation_here;
794  } else if (isa<TagDecl>(Instantiation)) {
795  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
796  << (TSK != TSK_ImplicitInstantiation)
797  << InstantiationTy;
798  Note = diag::note_template_decl_here;
799  } else {
800  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
801  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
802  Diag(PointOfInstantiation,
803  diag::err_explicit_instantiation_undefined_var_template)
804  << Instantiation;
805  Instantiation->setInvalidDecl();
806  } else
807  Diag(PointOfInstantiation,
808  diag::err_explicit_instantiation_undefined_member)
809  << /*static data member*/ 2 << Instantiation->getDeclName()
810  << Instantiation->getDeclContext();
811  Note = diag::note_explicit_instantiation_here;
812  }
813  }
814  if (Note) // Diagnostics were emitted.
815  Diag(Pattern->getLocation(), Note.getValue());
816 
817  // In general, Instantiation isn't marked invalid to get more than one
818  // error for multiple undefined instantiations. But the code that does
819  // explicit declaration -> explicit definition conversion can't handle
820  // invalid declarations, so mark as invalid in that case.
822  Instantiation->setInvalidDecl();
823  return true;
824 }
825 
826 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
827 /// that the template parameter 'PrevDecl' is being shadowed by a new
828 /// declaration at location Loc. Returns true to indicate that this is
829 /// an error, and false otherwise.
831  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
832 
833  // C++ [temp.local]p4:
834  // A template-parameter shall not be redeclared within its
835  // scope (including nested scopes).
836  //
837  // Make this a warning when MSVC compatibility is requested.
838  unsigned DiagId = getLangOpts().MSVCCompat ? diag::ext_template_param_shadow
839  : diag::err_template_param_shadow;
840  Diag(Loc, DiagId) << cast<NamedDecl>(PrevDecl)->getDeclName();
841  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
842 }
843 
844 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
845 /// the parameter D to reference the templated declaration and return a pointer
846 /// to the template declaration. Otherwise, do nothing to D and return null.
848  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
849  D = Temp->getTemplatedDecl();
850  return Temp;
851  }
852  return nullptr;
853 }
854 
856  SourceLocation EllipsisLoc) const {
857  assert(Kind == Template &&
858  "Only template template arguments can be pack expansions here");
859  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
860  "Template template argument pack expansion without packs");
861  ParsedTemplateArgument Result(*this);
862  Result.EllipsisLoc = EllipsisLoc;
863  return Result;
864 }
865 
867  const ParsedTemplateArgument &Arg) {
868 
869  switch (Arg.getKind()) {
871  TypeSourceInfo *DI;
872  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
873  if (!DI)
874  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
875  return TemplateArgumentLoc(TemplateArgument(T), DI);
876  }
877 
879  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
881  }
882 
884  TemplateName Template = Arg.getAsTemplate().get();
885  TemplateArgument TArg;
886  if (Arg.getEllipsisLoc().isValid())
887  TArg = TemplateArgument(Template, Optional<unsigned int>());
888  else
889  TArg = Template;
890  return TemplateArgumentLoc(TArg,
892  SemaRef.Context),
893  Arg.getLocation(),
894  Arg.getEllipsisLoc());
895  }
896  }
897 
898  llvm_unreachable("Unhandled parsed template argument");
899 }
900 
901 /// Translates template arguments as provided by the parser
902 /// into template arguments used by semantic analysis.
904  TemplateArgumentListInfo &TemplateArgs) {
905  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
906  TemplateArgs.addArgument(translateTemplateArgument(*this,
907  TemplateArgsIn[I]));
908 }
909 
911  SourceLocation Loc,
912  IdentifierInfo *Name) {
913  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
915  if (PrevDecl && PrevDecl->isTemplateParameter())
916  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
917 }
918 
919 /// Convert a parsed type into a parsed template argument. This is mostly
920 /// trivial, except that we may have parsed a C++17 deduced class template
921 /// specialization type, in which case we should form a template template
922 /// argument instead of a type template argument.
924  TypeSourceInfo *TInfo;
925  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
926  if (T.isNull())
927  return ParsedTemplateArgument();
928  assert(TInfo && "template argument with no location");
929 
930  // If we might have formed a deduced template specialization type, convert
931  // it to a template template argument.
932  if (getLangOpts().CPlusPlus17) {
933  TypeLoc TL = TInfo->getTypeLoc();
934  SourceLocation EllipsisLoc;
935  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
936  EllipsisLoc = PET.getEllipsisLoc();
937  TL = PET.getPatternLoc();
938  }
939 
940  CXXScopeSpec SS;
941  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
942  SS.Adopt(ET.getQualifierLoc());
943  TL = ET.getNamedTypeLoc();
944  }
945 
946  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
947  TemplateName Name = DTST.getTypePtr()->getTemplateName();
948  if (SS.isSet())
949  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
950  /*HasTemplateKeyword*/ false,
951  Name.getAsTemplateDecl());
952  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
953  DTST.getTemplateNameLoc());
954  if (EllipsisLoc.isValid())
955  Result = Result.getTemplatePackExpansion(EllipsisLoc);
956  return Result;
957  }
958  }
959 
960  // This is a normal type template argument. Note, if the type template
961  // argument is an injected-class-name for a template, it has a dual nature
962  // and can be used as either a type or a template. We handle that in
963  // convertTypeTemplateArgumentToTemplate.
965  ParsedType.get().getAsOpaquePtr(),
966  TInfo->getTypeLoc().getBeginLoc());
967 }
968 
969 /// ActOnTypeParameter - Called when a C++ template type parameter
970 /// (e.g., "typename T") has been parsed. Typename specifies whether
971 /// the keyword "typename" was used to declare the type parameter
972 /// (otherwise, "class" was used), and KeyLoc is the location of the
973 /// "class" or "typename" keyword. ParamName is the name of the
974 /// parameter (NULL indicates an unnamed template parameter) and
975 /// ParamNameLoc is the location of the parameter name (if any).
976 /// If the type parameter has a default argument, it will be added
977 /// later via ActOnTypeParameterDefault.
979  SourceLocation EllipsisLoc,
980  SourceLocation KeyLoc,
981  IdentifierInfo *ParamName,
982  SourceLocation ParamNameLoc,
983  unsigned Depth, unsigned Position,
984  SourceLocation EqualLoc,
985  ParsedType DefaultArg) {
986  assert(S->isTemplateParamScope() &&
987  "Template type parameter not in template parameter scope!");
988 
989  bool IsParameterPack = EllipsisLoc.isValid();
991  Context, Context.getTranslationUnitDecl(), KeyLoc, ParamNameLoc, Depth,
992  Position, ParamName, Typename, IsParameterPack);
993  Param->setAccess(AS_public);
994 
995  if (Param->isParameterPack())
996  if (auto *LSI = getEnclosingLambda())
997  LSI->LocalPacks.push_back(Param);
998 
999  if (ParamName) {
1000  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
1001 
1002  // Add the template parameter into the current scope.
1003  S->AddDecl(Param);
1004  IdResolver.AddDecl(Param);
1005  }
1006 
1007  // C++0x [temp.param]p9:
1008  // A default template-argument may be specified for any kind of
1009  // template-parameter that is not a template parameter pack.
1010  if (DefaultArg && IsParameterPack) {
1011  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1012  DefaultArg = nullptr;
1013  }
1014 
1015  // Handle the default argument, if provided.
1016  if (DefaultArg) {
1017  TypeSourceInfo *DefaultTInfo;
1018  GetTypeFromParser(DefaultArg, &DefaultTInfo);
1019 
1020  assert(DefaultTInfo && "expected source information for type");
1021 
1022  // Check for unexpanded parameter packs.
1023  if (DiagnoseUnexpandedParameterPack(ParamNameLoc, DefaultTInfo,
1024  UPPC_DefaultArgument))
1025  return Param;
1026 
1027  // Check the template argument itself.
1028  if (CheckTemplateArgument(Param, DefaultTInfo)) {
1029  Param->setInvalidDecl();
1030  return Param;
1031  }
1032 
1033  Param->setDefaultArgument(DefaultTInfo);
1034  }
1035 
1036  return Param;
1037 }
1038 
1039 /// Check that the type of a non-type template parameter is
1040 /// well-formed.
1041 ///
1042 /// \returns the (possibly-promoted) parameter type if valid;
1043 /// otherwise, produces a diagnostic and returns a NULL type.
1045  SourceLocation Loc) {
1046  if (TSI->getType()->isUndeducedType()) {
1047  // C++17 [temp.dep.expr]p3:
1048  // An id-expression is type-dependent if it contains
1049  // - an identifier associated by name lookup with a non-type
1050  // template-parameter declared with a type that contains a
1051  // placeholder type (7.1.7.4),
1052  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
1053  }
1054 
1055  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
1056 }
1057 
1059  SourceLocation Loc) {
1060  // We don't allow variably-modified types as the type of non-type template
1061  // parameters.
1062  if (T->isVariablyModifiedType()) {
1063  Diag(Loc, diag::err_variably_modified_nontype_template_param)
1064  << T;
1065  return QualType();
1066  }
1067 
1068  // C++ [temp.param]p4:
1069  //
1070  // A non-type template-parameter shall have one of the following
1071  // (optionally cv-qualified) types:
1072  //
1073  // -- integral or enumeration type,
1074  if (T->isIntegralOrEnumerationType() ||
1075  // -- pointer to object or pointer to function,
1076  T->isPointerType() ||
1077  // -- reference to object or reference to function,
1078  T->isReferenceType() ||
1079  // -- pointer to member,
1080  T->isMemberPointerType() ||
1081  // -- std::nullptr_t.
1082  T->isNullPtrType() ||
1083  // Allow use of auto in template parameter declarations.
1084  T->isUndeducedType()) {
1085  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1086  // are ignored when determining its type.
1087  return T.getUnqualifiedType();
1088  }
1089 
1090  // C++ [temp.param]p8:
1091  //
1092  // A non-type template-parameter of type "array of T" or
1093  // "function returning T" is adjusted to be of type "pointer to
1094  // T" or "pointer to function returning T", respectively.
1095  if (T->isArrayType() || T->isFunctionType())
1096  return Context.getDecayedType(T);
1097 
1098  // If T is a dependent type, we can't do the check now, so we
1099  // assume that it is well-formed. Note that stripping off the
1100  // qualifiers here is not really correct if T turns out to be
1101  // an array type, but we'll recompute the type everywhere it's
1102  // used during instantiation, so that should be OK. (Using the
1103  // qualified type is equally wrong.)
1104  if (T->isDependentType())
1105  return T.getUnqualifiedType();
1106 
1107  Diag(Loc, diag::err_template_nontype_parm_bad_type)
1108  << T;
1109 
1110  return QualType();
1111 }
1112 
1114  unsigned Depth,
1115  unsigned Position,
1116  SourceLocation EqualLoc,
1117  Expr *Default) {
1118  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1119 
1120  // Check that we have valid decl-specifiers specified.
1121  auto CheckValidDeclSpecifiers = [this, &D] {
1122  // C++ [temp.param]
1123  // p1
1124  // template-parameter:
1125  // ...
1126  // parameter-declaration
1127  // p2
1128  // ... A storage class shall not be specified in a template-parameter
1129  // declaration.
1130  // [dcl.typedef]p1:
1131  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1132  // of a parameter-declaration
1133  const DeclSpec &DS = D.getDeclSpec();
1134  auto EmitDiag = [this](SourceLocation Loc) {
1135  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1136  << FixItHint::CreateRemoval(Loc);
1137  };
1139  EmitDiag(DS.getStorageClassSpecLoc());
1140 
1142  EmitDiag(DS.getThreadStorageClassSpecLoc());
1143 
1144  // [dcl.inline]p1:
1145  // The inline specifier can be applied only to the declaration or
1146  // definition of a variable or function.
1147 
1148  if (DS.isInlineSpecified())
1149  EmitDiag(DS.getInlineSpecLoc());
1150 
1151  // [dcl.constexpr]p1:
1152  // The constexpr specifier shall be applied only to the definition of a
1153  // variable or variable template or the declaration of a function or
1154  // function template.
1155 
1156  if (DS.hasConstexprSpecifier())
1157  EmitDiag(DS.getConstexprSpecLoc());
1158 
1159  // [dcl.fct.spec]p1:
1160  // Function-specifiers can be used only in function declarations.
1161 
1162  if (DS.isVirtualSpecified())
1163  EmitDiag(DS.getVirtualSpecLoc());
1164 
1165  if (DS.hasExplicitSpecifier())
1166  EmitDiag(DS.getExplicitSpecLoc());
1167 
1168  if (DS.isNoreturnSpecified())
1169  EmitDiag(DS.getNoreturnSpecLoc());
1170  };
1171 
1172  CheckValidDeclSpecifiers();
1173 
1174  if (TInfo->getType()->isUndeducedType()) {
1175  Diag(D.getIdentifierLoc(),
1176  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1177  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1178  }
1179 
1180  assert(S->isTemplateParamScope() &&
1181  "Non-type template parameter not in template parameter scope!");
1182  bool Invalid = false;
1183 
1184  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1185  if (T.isNull()) {
1186  T = Context.IntTy; // Recover with an 'int' type.
1187  Invalid = true;
1188  }
1189 
1190  CheckFunctionOrTemplateParamDeclarator(S, D);
1191 
1192  IdentifierInfo *ParamName = D.getIdentifier();
1193  bool IsParameterPack = D.hasEllipsis();
1195  Context, Context.getTranslationUnitDecl(), D.getBeginLoc(),
1196  D.getIdentifierLoc(), Depth, Position, ParamName, T, IsParameterPack,
1197  TInfo);
1198  Param->setAccess(AS_public);
1199 
1200  if (Invalid)
1201  Param->setInvalidDecl();
1202 
1203  if (Param->isParameterPack())
1204  if (auto *LSI = getEnclosingLambda())
1205  LSI->LocalPacks.push_back(Param);
1206 
1207  if (ParamName) {
1209  ParamName);
1210 
1211  // Add the template parameter into the current scope.
1212  S->AddDecl(Param);
1213  IdResolver.AddDecl(Param);
1214  }
1215 
1216  // C++0x [temp.param]p9:
1217  // A default template-argument may be specified for any kind of
1218  // template-parameter that is not a template parameter pack.
1219  if (Default && IsParameterPack) {
1220  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1221  Default = nullptr;
1222  }
1223 
1224  // Check the well-formedness of the default template argument, if provided.
1225  if (Default) {
1226  // Check for unexpanded parameter packs.
1227  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1228  return Param;
1229 
1230  TemplateArgument Converted;
1231  ExprResult DefaultRes =
1232  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1233  if (DefaultRes.isInvalid()) {
1234  Param->setInvalidDecl();
1235  return Param;
1236  }
1237  Default = DefaultRes.get();
1238 
1239  Param->setDefaultArgument(Default);
1240  }
1241 
1242  return Param;
1243 }
1244 
1245 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1246 /// parameter (e.g. T in template <template <typename> class T> class array)
1247 /// has been parsed. S is the current scope.
1249  SourceLocation TmpLoc,
1250  TemplateParameterList *Params,
1251  SourceLocation EllipsisLoc,
1252  IdentifierInfo *Name,
1253  SourceLocation NameLoc,
1254  unsigned Depth,
1255  unsigned Position,
1256  SourceLocation EqualLoc,
1257  ParsedTemplateArgument Default) {
1258  assert(S->isTemplateParamScope() &&
1259  "Template template parameter not in template parameter scope!");
1260 
1261  // Construct the parameter object.
1262  bool IsParameterPack = EllipsisLoc.isValid();
1263  TemplateTemplateParmDecl *Param =
1265  NameLoc.isInvalid()? TmpLoc : NameLoc,
1266  Depth, Position, IsParameterPack,
1267  Name, Params);
1268  Param->setAccess(AS_public);
1269 
1270  if (Param->isParameterPack())
1271  if (auto *LSI = getEnclosingLambda())
1272  LSI->LocalPacks.push_back(Param);
1273 
1274  // If the template template parameter has a name, then link the identifier
1275  // into the scope and lookup mechanisms.
1276  if (Name) {
1277  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1278 
1279  S->AddDecl(Param);
1280  IdResolver.AddDecl(Param);
1281  }
1282 
1283  if (Params->size() == 0) {
1284  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1285  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1286  Param->setInvalidDecl();
1287  }
1288 
1289  // C++0x [temp.param]p9:
1290  // A default template-argument may be specified for any kind of
1291  // template-parameter that is not a template parameter pack.
1292  if (IsParameterPack && !Default.isInvalid()) {
1293  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1294  Default = ParsedTemplateArgument();
1295  }
1296 
1297  if (!Default.isInvalid()) {
1298  // Check only that we have a template template argument. We don't want to
1299  // try to check well-formedness now, because our template template parameter
1300  // might have dependent types in its template parameters, which we wouldn't
1301  // be able to match now.
1302  //
1303  // If none of the template template parameter's template arguments mention
1304  // other template parameters, we could actually perform more checking here.
1305  // However, it isn't worth doing.
1306  TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
1307  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1308  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1309  << DefaultArg.getSourceRange();
1310  return Param;
1311  }
1312 
1313  // Check for unexpanded parameter packs.
1314  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1315  DefaultArg.getArgument().getAsTemplate(),
1316  UPPC_DefaultArgument))
1317  return Param;
1318 
1319  Param->setDefaultArgument(Context, DefaultArg);
1320  }
1321 
1322  return Param;
1323 }
1324 
1325 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1326 /// constrained by RequiresClause, that contains the template parameters in
1327 /// Params.
1330  SourceLocation ExportLoc,
1331  SourceLocation TemplateLoc,
1332  SourceLocation LAngleLoc,
1333  ArrayRef<NamedDecl *> Params,
1334  SourceLocation RAngleLoc,
1335  Expr *RequiresClause) {
1336  if (ExportLoc.isValid())
1337  Diag(ExportLoc, diag::warn_template_export_unsupported);
1338 
1340  Context, TemplateLoc, LAngleLoc,
1341  llvm::makeArrayRef(Params.data(), Params.size()),
1342  RAngleLoc, RequiresClause);
1343 }
1344 
1346  const CXXScopeSpec &SS) {
1347  if (SS.isSet())
1349 }
1350 
1352  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1353  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1354  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1355  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1356  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1357  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1358  assert(TemplateParams && TemplateParams->size() > 0 &&
1359  "No template parameters");
1360  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1361  bool Invalid = false;
1362 
1363  // Check that we can declare a template here.
1364  if (CheckTemplateDeclScope(S, TemplateParams))
1365  return true;
1366 
1368  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1369 
1370  // There is no such thing as an unnamed class template.
1371  if (!Name) {
1372  Diag(KWLoc, diag::err_template_unnamed_class);
1373  return true;
1374  }
1375 
1376  // Find any previous declaration with this name. For a friend with no
1377  // scope explicitly specified, we only look for tag declarations (per
1378  // C++11 [basic.lookup.elab]p2).
1379  DeclContext *SemanticContext;
1380  LookupResult Previous(*this, Name, NameLoc,
1381  (SS.isEmpty() && TUK == TUK_Friend)
1382  ? LookupTagName : LookupOrdinaryName,
1383  forRedeclarationInCurContext());
1384  if (SS.isNotEmpty() && !SS.isInvalid()) {
1385  SemanticContext = computeDeclContext(SS, true);
1386  if (!SemanticContext) {
1387  // FIXME: Horrible, horrible hack! We can't currently represent this
1388  // in the AST, and historically we have just ignored such friend
1389  // class templates, so don't complain here.
1390  Diag(NameLoc, TUK == TUK_Friend
1391  ? diag::warn_template_qualified_friend_ignored
1392  : diag::err_template_qualified_declarator_no_match)
1393  << SS.getScopeRep() << SS.getRange();
1394  return TUK != TUK_Friend;
1395  }
1396 
1397  if (RequireCompleteDeclContext(SS, SemanticContext))
1398  return true;
1399 
1400  // If we're adding a template to a dependent context, we may need to
1401  // rebuilding some of the types used within the template parameter list,
1402  // now that we know what the current instantiation is.
1403  if (SemanticContext->isDependentContext()) {
1404  ContextRAII SavedContext(*this, SemanticContext);
1405  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1406  Invalid = true;
1407  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1408  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1409 
1410  LookupQualifiedName(Previous, SemanticContext);
1411  } else {
1412  SemanticContext = CurContext;
1413 
1414  // C++14 [class.mem]p14:
1415  // If T is the name of a class, then each of the following shall have a
1416  // name different from T:
1417  // -- every member template of class T
1418  if (TUK != TUK_Friend &&
1419  DiagnoseClassNameShadow(SemanticContext,
1420  DeclarationNameInfo(Name, NameLoc)))
1421  return true;
1422 
1423  LookupName(Previous, S);
1424  }
1425 
1426  if (Previous.isAmbiguous())
1427  return true;
1428 
1429  NamedDecl *PrevDecl = nullptr;
1430  if (Previous.begin() != Previous.end())
1431  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1432 
1433  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1434  // Maybe we will complain about the shadowed template parameter.
1435  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1436  // Just pretend that we didn't see the previous declaration.
1437  PrevDecl = nullptr;
1438  }
1439 
1440  // If there is a previous declaration with the same name, check
1441  // whether this is a valid redeclaration.
1442  ClassTemplateDecl *PrevClassTemplate =
1443  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1444 
1445  // We may have found the injected-class-name of a class template,
1446  // class template partial specialization, or class template specialization.
1447  // In these cases, grab the template that is being defined or specialized.
1448  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1449  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1450  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1451  PrevClassTemplate
1452  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1453  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1454  PrevClassTemplate
1455  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1456  ->getSpecializedTemplate();
1457  }
1458  }
1459 
1460  if (TUK == TUK_Friend) {
1461  // C++ [namespace.memdef]p3:
1462  // [...] When looking for a prior declaration of a class or a function
1463  // declared as a friend, and when the name of the friend class or
1464  // function is neither a qualified name nor a template-id, scopes outside
1465  // the innermost enclosing namespace scope are not considered.
1466  if (!SS.isSet()) {
1467  DeclContext *OutermostContext = CurContext;
1468  while (!OutermostContext->isFileContext())
1469  OutermostContext = OutermostContext->getLookupParent();
1470 
1471  if (PrevDecl &&
1472  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1473  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1474  SemanticContext = PrevDecl->getDeclContext();
1475  } else {
1476  // Declarations in outer scopes don't matter. However, the outermost
1477  // context we computed is the semantic context for our new
1478  // declaration.
1479  PrevDecl = PrevClassTemplate = nullptr;
1480  SemanticContext = OutermostContext;
1481 
1482  // Check that the chosen semantic context doesn't already contain a
1483  // declaration of this name as a non-tag type.
1484  Previous.clear(LookupOrdinaryName);
1485  DeclContext *LookupContext = SemanticContext;
1486  while (LookupContext->isTransparentContext())
1487  LookupContext = LookupContext->getLookupParent();
1488  LookupQualifiedName(Previous, LookupContext);
1489 
1490  if (Previous.isAmbiguous())
1491  return true;
1492 
1493  if (Previous.begin() != Previous.end())
1494  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1495  }
1496  }
1497  } else if (PrevDecl &&
1498  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1499  S, SS.isValid()))
1500  PrevDecl = PrevClassTemplate = nullptr;
1501 
1502  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1503  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1504  if (SS.isEmpty() &&
1505  !(PrevClassTemplate &&
1506  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1507  SemanticContext->getRedeclContext()))) {
1508  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1509  Diag(Shadow->getTargetDecl()->getLocation(),
1510  diag::note_using_decl_target);
1511  Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1512  // Recover by ignoring the old declaration.
1513  PrevDecl = PrevClassTemplate = nullptr;
1514  }
1515  }
1516 
1517  if (PrevClassTemplate) {
1518  // Ensure that the template parameter lists are compatible. Skip this check
1519  // for a friend in a dependent context: the template parameter list itself
1520  // could be dependent.
1521  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1522  !TemplateParameterListsAreEqual(TemplateParams,
1523  PrevClassTemplate->getTemplateParameters(),
1524  /*Complain=*/true,
1525  TPL_TemplateMatch))
1526  return true;
1527 
1528  // C++ [temp.class]p4:
1529  // In a redeclaration, partial specialization, explicit
1530  // specialization or explicit instantiation of a class template,
1531  // the class-key shall agree in kind with the original class
1532  // template declaration (7.1.5.3).
1533  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1534  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1535  TUK == TUK_Definition, KWLoc, Name)) {
1536  Diag(KWLoc, diag::err_use_with_wrong_tag)
1537  << Name
1538  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1539  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1540  Kind = PrevRecordDecl->getTagKind();
1541  }
1542 
1543  // Check for redefinition of this class template.
1544  if (TUK == TUK_Definition) {
1545  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1546  // If we have a prior definition that is not visible, treat this as
1547  // simply making that previous definition visible.
1548  NamedDecl *Hidden = nullptr;
1549  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1550  SkipBody->ShouldSkip = true;
1551  SkipBody->Previous = Def;
1552  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1553  assert(Tmpl && "original definition of a class template is not a "
1554  "class template?");
1555  makeMergedDefinitionVisible(Hidden);
1556  makeMergedDefinitionVisible(Tmpl);
1557  } else {
1558  Diag(NameLoc, diag::err_redefinition) << Name;
1559  Diag(Def->getLocation(), diag::note_previous_definition);
1560  // FIXME: Would it make sense to try to "forget" the previous
1561  // definition, as part of error recovery?
1562  return true;
1563  }
1564  }
1565  }
1566  } else if (PrevDecl) {
1567  // C++ [temp]p5:
1568  // A class template shall not have the same name as any other
1569  // template, class, function, object, enumeration, enumerator,
1570  // namespace, or type in the same scope (3.3), except as specified
1571  // in (14.5.4).
1572  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1573  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1574  return true;
1575  }
1576 
1577  // Check the template parameter list of this declaration, possibly
1578  // merging in the template parameter list from the previous class
1579  // template declaration. Skip this check for a friend in a dependent
1580  // context, because the template parameter list might be dependent.
1581  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1582  CheckTemplateParameterList(
1583  TemplateParams,
1584  PrevClassTemplate
1585  ? PrevClassTemplate->getMostRecentDecl()->getTemplateParameters()
1586  : nullptr,
1587  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1588  SemanticContext->isDependentContext())
1589  ? TPC_ClassTemplateMember
1590  : TUK == TUK_Friend ? TPC_FriendClassTemplate : TPC_ClassTemplate,
1591  SkipBody))
1592  Invalid = true;
1593 
1594  if (SS.isSet()) {
1595  // If the name of the template was qualified, we must be defining the
1596  // template out-of-line.
1597  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1598  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1599  : diag::err_member_decl_does_not_match)
1600  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1601  Invalid = true;
1602  }
1603  }
1604 
1605  // If this is a templated friend in a dependent context we should not put it
1606  // on the redecl chain. In some cases, the templated friend can be the most
1607  // recent declaration tricking the template instantiator to make substitutions
1608  // there.
1609  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1610  bool ShouldAddRedecl
1611  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1612 
1613  CXXRecordDecl *NewClass =
1614  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1615  PrevClassTemplate && ShouldAddRedecl ?
1616  PrevClassTemplate->getTemplatedDecl() : nullptr,
1617  /*DelayTypeCreation=*/true);
1618  SetNestedNameSpecifier(*this, NewClass, SS);
1619  if (NumOuterTemplateParamLists > 0)
1621  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1622  NumOuterTemplateParamLists));
1623 
1624  // Add alignment attributes if necessary; these attributes are checked when
1625  // the ASTContext lays out the structure.
1626  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
1627  AddAlignmentAttributesForRecord(NewClass);
1628  AddMsStructLayoutForRecord(NewClass);
1629  }
1630 
1631  ClassTemplateDecl *NewTemplate
1632  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1633  DeclarationName(Name), TemplateParams,
1634  NewClass);
1635 
1636  if (ShouldAddRedecl)
1637  NewTemplate->setPreviousDecl(PrevClassTemplate);
1638 
1639  NewClass->setDescribedClassTemplate(NewTemplate);
1640 
1641  if (ModulePrivateLoc.isValid())
1642  NewTemplate->setModulePrivate();
1643 
1644  // Build the type for the class template declaration now.
1645  QualType T = NewTemplate->getInjectedClassNameSpecialization();
1646  T = Context.getInjectedClassNameType(NewClass, T);
1647  assert(T->isDependentType() && "Class template type is not dependent?");
1648  (void)T;
1649 
1650  // If we are providing an explicit specialization of a member that is a
1651  // class template, make a note of that.
1652  if (PrevClassTemplate &&
1653  PrevClassTemplate->getInstantiatedFromMemberTemplate())
1654  PrevClassTemplate->setMemberSpecialization();
1655 
1656  // Set the access specifier.
1657  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1658  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1659 
1660  // Set the lexical context of these templates
1661  NewClass->setLexicalDeclContext(CurContext);
1662  NewTemplate->setLexicalDeclContext(CurContext);
1663 
1664  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
1665  NewClass->startDefinition();
1666 
1667  ProcessDeclAttributeList(S, NewClass, Attr);
1668 
1669  if (PrevClassTemplate)
1670  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1671 
1672  AddPushedVisibilityAttribute(NewClass);
1673  inferGslOwnerPointerAttribute(NewClass);
1674 
1675  if (TUK != TUK_Friend) {
1676  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
1677  Scope *Outer = S;
1678  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
1679  Outer = Outer->getParent();
1680  PushOnScopeChains(NewTemplate, Outer);
1681  } else {
1682  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1683  NewTemplate->setAccess(PrevClassTemplate->getAccess());
1684  NewClass->setAccess(PrevClassTemplate->getAccess());
1685  }
1686 
1687  NewTemplate->setObjectOfFriendDecl();
1688 
1689  // Friend templates are visible in fairly strange ways.
1690  if (!CurContext->isDependentContext()) {
1691  DeclContext *DC = SemanticContext->getRedeclContext();
1692  DC->makeDeclVisibleInContext(NewTemplate);
1693  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1694  PushOnScopeChains(NewTemplate, EnclosingScope,
1695  /* AddToContext = */ false);
1696  }
1697 
1698  FriendDecl *Friend = FriendDecl::Create(
1699  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
1700  Friend->setAccess(AS_public);
1701  CurContext->addDecl(Friend);
1702  }
1703 
1704  if (PrevClassTemplate)
1705  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
1706 
1707  if (Invalid) {
1708  NewTemplate->setInvalidDecl();
1709  NewClass->setInvalidDecl();
1710  }
1711 
1712  ActOnDocumentableDecl(NewTemplate);
1713 
1714  if (SkipBody && SkipBody->ShouldSkip)
1715  return SkipBody->Previous;
1716 
1717  return NewTemplate;
1718 }
1719 
1720 namespace {
1721 /// Tree transform to "extract" a transformed type from a class template's
1722 /// constructor to a deduction guide.
1723 class ExtractTypeForDeductionGuide
1724  : public TreeTransform<ExtractTypeForDeductionGuide> {
1725 public:
1727  ExtractTypeForDeductionGuide(Sema &SemaRef) : Base(SemaRef) {}
1728 
1729  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
1730 
1731  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
1732  return TransformType(
1733  TLB,
1735  }
1736 };
1737 
1738 /// Transform to convert portions of a constructor declaration into the
1739 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
1740 struct ConvertConstructorToDeductionGuideTransform {
1741  ConvertConstructorToDeductionGuideTransform(Sema &S,
1742  ClassTemplateDecl *Template)
1743  : SemaRef(S), Template(Template) {}
1744 
1745  Sema &SemaRef;
1746  ClassTemplateDecl *Template;
1747 
1748  DeclContext *DC = Template->getDeclContext();
1749  CXXRecordDecl *Primary = Template->getTemplatedDecl();
1750  DeclarationName DeductionGuideName =
1752 
1753  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
1754 
1755  // Index adjustment to apply to convert depth-1 template parameters into
1756  // depth-0 template parameters.
1757  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
1758 
1759  /// Transform a constructor declaration into a deduction guide.
1760  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
1761  CXXConstructorDecl *CD) {
1763 
1764  LocalInstantiationScope Scope(SemaRef);
1765 
1766  // C++ [over.match.class.deduct]p1:
1767  // -- For each constructor of the class template designated by the
1768  // template-name, a function template with the following properties:
1769 
1770  // -- The template parameters are the template parameters of the class
1771  // template followed by the template parameters (including default
1772  // template arguments) of the constructor, if any.
1773  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
1774  if (FTD) {
1775  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
1776  SmallVector<NamedDecl *, 16> AllParams;
1777  AllParams.reserve(TemplateParams->size() + InnerParams->size());
1778  AllParams.insert(AllParams.begin(),
1779  TemplateParams->begin(), TemplateParams->end());
1780  SubstArgs.reserve(InnerParams->size());
1781 
1782  // Later template parameters could refer to earlier ones, so build up
1783  // a list of substituted template arguments as we go.
1784  for (NamedDecl *Param : *InnerParams) {
1786  Args.addOuterTemplateArguments(SubstArgs);
1787  Args.addOuterRetainedLevel();
1788  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
1789  if (!NewParam)
1790  return nullptr;
1791  AllParams.push_back(NewParam);
1792  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
1793  SemaRef.Context.getInjectedTemplateArg(NewParam)));
1794  }
1795  TemplateParams = TemplateParameterList::Create(
1796  SemaRef.Context, InnerParams->getTemplateLoc(),
1797  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
1798  /*FIXME: RequiresClause*/ nullptr);
1799  }
1800 
1801  // If we built a new template-parameter-list, track that we need to
1802  // substitute references to the old parameters into references to the
1803  // new ones.
1805  if (FTD) {
1806  Args.addOuterTemplateArguments(SubstArgs);
1807  Args.addOuterRetainedLevel();
1808  }
1809 
1812  assert(FPTL && "no prototype for constructor declaration");
1813 
1814  // Transform the type of the function, adjusting the return type and
1815  // replacing references to the old parameters with references to the
1816  // new ones.
1817  TypeLocBuilder TLB;
1819  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args);
1820  if (NewType.isNull())
1821  return nullptr;
1822  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
1823 
1824  return buildDeductionGuide(TemplateParams, CD->getExplicitSpecifier(),
1825  NewTInfo, CD->getBeginLoc(), CD->getLocation(),
1826  CD->getEndLoc());
1827  }
1828 
1829  /// Build a deduction guide with the specified parameter types.
1830  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
1831  SourceLocation Loc = Template->getLocation();
1832 
1833  // Build the requested type.
1835  EPI.HasTrailingReturn = true;
1836  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
1837  DeductionGuideName, EPI);
1838  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
1839 
1840  FunctionProtoTypeLoc FPTL =
1842 
1843  // Build the parameters, needed during deduction / substitution.
1845  for (auto T : ParamTypes) {
1846  ParmVarDecl *NewParam = ParmVarDecl::Create(
1847  SemaRef.Context, DC, Loc, Loc, nullptr, T,
1848  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
1849  NewParam->setScopeInfo(0, Params.size());
1850  FPTL.setParam(Params.size(), NewParam);
1851  Params.push_back(NewParam);
1852  }
1853 
1854  return buildDeductionGuide(Template->getTemplateParameters(),
1855  ExplicitSpecifier(), TSI, Loc, Loc, Loc);
1856  }
1857 
1858 private:
1859  /// Transform a constructor template parameter into a deduction guide template
1860  /// parameter, rebuilding any internal references to earlier parameters and
1861  /// renumbering as we go.
1862  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
1864  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
1865  // TemplateTypeParmDecl's index cannot be changed after creation, so
1866  // substitute it directly.
1867  auto *NewTTP = TemplateTypeParmDecl::Create(
1868  SemaRef.Context, DC, TTP->getBeginLoc(), TTP->getLocation(),
1869  /*Depth*/ 0, Depth1IndexAdjustment + TTP->getIndex(),
1870  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
1871  TTP->isParameterPack());
1872  if (TTP->hasDefaultArgument()) {
1873  TypeSourceInfo *InstantiatedDefaultArg =
1874  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
1875  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
1876  if (InstantiatedDefaultArg)
1877  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
1878  }
1879  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
1880  NewTTP);
1881  return NewTTP;
1882  }
1883 
1884  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
1885  return transformTemplateParameterImpl(TTP, Args);
1886 
1887  return transformTemplateParameterImpl(
1888  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
1889  }
1890  template<typename TemplateParmDecl>
1891  TemplateParmDecl *
1892  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
1894  // Ask the template instantiator to do the heavy lifting for us, then adjust
1895  // the index of the parameter once it's done.
1896  auto *NewParam =
1897  cast_or_null<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
1898  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
1899  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
1900  return NewParam;
1901  }
1902 
1903  QualType transformFunctionProtoType(TypeLocBuilder &TLB,
1907  SmallVector<QualType, 4> ParamTypes;
1908  const FunctionProtoType *T = TL.getTypePtr();
1909 
1910  // -- The types of the function parameters are those of the constructor.
1911  for (auto *OldParam : TL.getParams()) {
1912  ParmVarDecl *NewParam = transformFunctionTypeParam(OldParam, Args);
1913  if (!NewParam)
1914  return QualType();
1915  ParamTypes.push_back(NewParam->getType());
1916  Params.push_back(NewParam);
1917  }
1918 
1919  // -- The return type is the class template specialization designated by
1920  // the template-name and template arguments corresponding to the
1921  // template parameters obtained from the class template.
1922  //
1923  // We use the injected-class-name type of the primary template instead.
1924  // This has the convenient property that it is different from any type that
1925  // the user can write in a deduction-guide (because they cannot enter the
1926  // context of the template), so implicit deduction guides can never collide
1927  // with explicit ones.
1928  QualType ReturnType = DeducedType;
1929  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
1930 
1931  // Resolving a wording defect, we also inherit the variadicness of the
1932  // constructor.
1934  EPI.Variadic = T->isVariadic();
1935  EPI.HasTrailingReturn = true;
1936 
1937  QualType Result = SemaRef.BuildFunctionType(
1938  ReturnType, ParamTypes, TL.getBeginLoc(), DeductionGuideName, EPI);
1939  if (Result.isNull())
1940  return QualType();
1941 
1942  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
1944  NewTL.setLParenLoc(TL.getLParenLoc());
1945  NewTL.setRParenLoc(TL.getRParenLoc());
1947  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
1948  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
1949  NewTL.setParam(I, Params[I]);
1950 
1951  return Result;
1952  }
1953 
1954  ParmVarDecl *
1955  transformFunctionTypeParam(ParmVarDecl *OldParam,
1957  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
1958  TypeSourceInfo *NewDI;
1959  if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
1960  // Expand out the one and only element in each inner pack.
1961  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
1962  NewDI =
1963  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
1964  OldParam->getLocation(), OldParam->getDeclName());
1965  if (!NewDI) return nullptr;
1966  NewDI =
1967  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
1968  PackTL.getTypePtr()->getNumExpansions());
1969  } else
1970  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
1971  OldParam->getDeclName());
1972  if (!NewDI)
1973  return nullptr;
1974 
1975  // Extract the type. This (for instance) replaces references to typedef
1976  // members of the current instantiations with the definitions of those
1977  // typedefs, avoiding triggering instantiation of the deduced type during
1978  // deduction.
1979  NewDI = ExtractTypeForDeductionGuide(SemaRef).transform(NewDI);
1980 
1981  // Resolving a wording defect, we also inherit default arguments from the
1982  // constructor.
1983  ExprResult NewDefArg;
1984  if (OldParam->hasDefaultArg()) {
1985  NewDefArg = SemaRef.SubstExpr(OldParam->getDefaultArg(), Args);
1986  if (NewDefArg.isInvalid())
1987  return nullptr;
1988  }
1989 
1990  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
1991  OldParam->getInnerLocStart(),
1992  OldParam->getLocation(),
1993  OldParam->getIdentifier(),
1994  NewDI->getType(),
1995  NewDI,
1996  OldParam->getStorageClass(),
1997  NewDefArg.get());
1998  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
1999  OldParam->getFunctionScopeIndex());
2000  SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
2001  return NewParam;
2002  }
2003 
2004  NamedDecl *buildDeductionGuide(TemplateParameterList *TemplateParams,
2005  ExplicitSpecifier ES, TypeSourceInfo *TInfo,
2006  SourceLocation LocStart, SourceLocation Loc,
2007  SourceLocation LocEnd) {
2008  DeclarationNameInfo Name(DeductionGuideName, Loc);
2009  ArrayRef<ParmVarDecl *> Params =
2010  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
2011 
2012  // Build the implicit deduction guide template.
2013  auto *Guide =
2014  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, ES, Name,
2015  TInfo->getType(), TInfo, LocEnd);
2016  Guide->setImplicit();
2017  Guide->setParams(Params);
2018 
2019  for (auto *Param : Params)
2020  Param->setDeclContext(Guide);
2021 
2022  auto *GuideTemplate = FunctionTemplateDecl::Create(
2023  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
2024  GuideTemplate->setImplicit();
2025  Guide->setDescribedFunctionTemplate(GuideTemplate);
2026 
2027  if (isa<CXXRecordDecl>(DC)) {
2028  Guide->setAccess(AS_public);
2029  GuideTemplate->setAccess(AS_public);
2030  }
2031 
2032  DC->addDecl(GuideTemplate);
2033  return GuideTemplate;
2034  }
2035 };
2036 }
2037 
2039  SourceLocation Loc) {
2040  if (CXXRecordDecl *DefRecord =
2041  cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
2042  TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
2043  Template = DescribedTemplate ? DescribedTemplate : Template;
2044  }
2045 
2046  DeclContext *DC = Template->getDeclContext();
2047  if (DC->isDependentContext())
2048  return;
2049 
2050  ConvertConstructorToDeductionGuideTransform Transform(
2051  *this, cast<ClassTemplateDecl>(Template));
2052  if (!isCompleteType(Loc, Transform.DeducedType))
2053  return;
2054 
2055  // Check whether we've already declared deduction guides for this template.
2056  // FIXME: Consider storing a flag on the template to indicate this.
2057  auto Existing = DC->lookup(Transform.DeductionGuideName);
2058  for (auto *D : Existing)
2059  if (D->isImplicit())
2060  return;
2061 
2062  // In case we were expanding a pack when we attempted to declare deduction
2063  // guides, turn off pack expansion for everything we're about to do.
2064  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
2065  // Create a template instantiation record to track the "instantiation" of
2066  // constructors into deduction guides.
2067  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
2068  // this substitution process actually fail?
2069  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
2070  if (BuildingDeductionGuides.isInvalid())
2071  return;
2072 
2073  // Convert declared constructors into deduction guide templates.
2074  // FIXME: Skip constructors for which deduction must necessarily fail (those
2075  // for which some class template parameter without a default argument never
2076  // appears in a deduced context).
2077  bool AddedAny = false;
2078  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2079  D = D->getUnderlyingDecl();
2080  if (D->isInvalidDecl() || D->isImplicit())
2081  continue;
2082  D = cast<NamedDecl>(D->getCanonicalDecl());
2083 
2084  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2085  auto *CD =
2086  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2087  // Class-scope explicit specializations (MS extension) do not result in
2088  // deduction guides.
2089  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2090  continue;
2091 
2092  Transform.transformConstructor(FTD, CD);
2093  AddedAny = true;
2094  }
2095 
2096  // C++17 [over.match.class.deduct]
2097  // -- If C is not defined or does not declare any constructors, an
2098  // additional function template derived as above from a hypothetical
2099  // constructor C().
2100  if (!AddedAny)
2101  Transform.buildSimpleDeductionGuide(None);
2102 
2103  // -- An additional function template derived as above from a hypothetical
2104  // constructor C(C), called the copy deduction candidate.
2105  cast<CXXDeductionGuideDecl>(
2106  cast<FunctionTemplateDecl>(
2107  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2108  ->getTemplatedDecl())
2109  ->setIsCopyDeductionCandidate();
2110 }
2111 
2112 /// Diagnose the presence of a default template argument on a
2113 /// template parameter, which is ill-formed in certain contexts.
2114 ///
2115 /// \returns true if the default template argument should be dropped.
2118  SourceLocation ParamLoc,
2119  SourceRange DefArgRange) {
2120  switch (TPC) {
2122  case Sema::TPC_VarTemplate:
2124  return false;
2125 
2128  // C++ [temp.param]p9:
2129  // A default template-argument shall not be specified in a
2130  // function template declaration or a function template
2131  // definition [...]
2132  // If a friend function template declaration specifies a default
2133  // template-argument, that declaration shall be a definition and shall be
2134  // the only declaration of the function template in the translation unit.
2135  // (C++98/03 doesn't have this wording; see DR226).
2136  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2137  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2138  : diag::ext_template_parameter_default_in_function_template)
2139  << DefArgRange;
2140  return false;
2141 
2143  // C++0x [temp.param]p9:
2144  // A default template-argument shall not be specified in the
2145  // template-parameter-lists of the definition of a member of a
2146  // class template that appears outside of the member's class.
2147  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2148  << DefArgRange;
2149  return true;
2150 
2153  // C++ [temp.param]p9:
2154  // A default template-argument shall not be specified in a
2155  // friend template declaration.
2156  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2157  << DefArgRange;
2158  return true;
2159 
2160  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2161  // for friend function templates if there is only a single
2162  // declaration (and it is a definition). Strange!
2163  }
2164 
2165  llvm_unreachable("Invalid TemplateParamListContext!");
2166 }
2167 
2168 /// Check for unexpanded parameter packs within the template parameters
2169 /// of a template template parameter, recursively.
2171  TemplateTemplateParmDecl *TTP) {
2172  // A template template parameter which is a parameter pack is also a pack
2173  // expansion.
2174  if (TTP->isParameterPack())
2175  return false;
2176 
2178  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2179  NamedDecl *P = Params->getParam(I);
2180  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2181  if (!NTTP->isParameterPack() &&
2182  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2183  NTTP->getTypeSourceInfo(),
2185  return true;
2186 
2187  continue;
2188  }
2189 
2190  if (TemplateTemplateParmDecl *InnerTTP
2191  = dyn_cast<TemplateTemplateParmDecl>(P))
2192  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2193  return true;
2194  }
2195 
2196  return false;
2197 }
2198 
2199 /// Checks the validity of a template parameter list, possibly
2200 /// considering the template parameter list from a previous
2201 /// declaration.
2202 ///
2203 /// If an "old" template parameter list is provided, it must be
2204 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2205 /// template parameter list.
2206 ///
2207 /// \param NewParams Template parameter list for a new template
2208 /// declaration. This template parameter list will be updated with any
2209 /// default arguments that are carried through from the previous
2210 /// template parameter list.
2211 ///
2212 /// \param OldParams If provided, template parameter list from a
2213 /// previous declaration of the same template. Default template
2214 /// arguments will be merged from the old template parameter list to
2215 /// the new template parameter list.
2216 ///
2217 /// \param TPC Describes the context in which we are checking the given
2218 /// template parameter list.
2219 ///
2220 /// \param SkipBody If we might have already made a prior merged definition
2221 /// of this template visible, the corresponding body-skipping information.
2222 /// Default argument redefinition is not an error when skipping such a body,
2223 /// because (under the ODR) we can assume the default arguments are the same
2224 /// as the prior merged definition.
2225 ///
2226 /// \returns true if an error occurred, false otherwise.
2228  TemplateParameterList *OldParams,
2230  SkipBodyInfo *SkipBody) {
2231  bool Invalid = false;
2232 
2233  // C++ [temp.param]p10:
2234  // The set of default template-arguments available for use with a
2235  // template declaration or definition is obtained by merging the
2236  // default arguments from the definition (if in scope) and all
2237  // declarations in scope in the same way default function
2238  // arguments are (8.3.6).
2239  bool SawDefaultArgument = false;
2240  SourceLocation PreviousDefaultArgLoc;
2241 
2242  // Dummy initialization to avoid warnings.
2243  TemplateParameterList::iterator OldParam = NewParams->end();
2244  if (OldParams)
2245  OldParam = OldParams->begin();
2246 
2247  bool RemoveDefaultArguments = false;
2248  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2249  NewParamEnd = NewParams->end();
2250  NewParam != NewParamEnd; ++NewParam) {
2251  // Variables used to diagnose redundant default arguments
2252  bool RedundantDefaultArg = false;
2253  SourceLocation OldDefaultLoc;
2254  SourceLocation NewDefaultLoc;
2255 
2256  // Variable used to diagnose missing default arguments
2257  bool MissingDefaultArg = false;
2258 
2259  // Variable used to diagnose non-final parameter packs
2260  bool SawParameterPack = false;
2261 
2262  if (TemplateTypeParmDecl *NewTypeParm
2263  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2264  // Check the presence of a default argument here.
2265  if (NewTypeParm->hasDefaultArgument() &&
2267  NewTypeParm->getLocation(),
2268  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2269  .getSourceRange()))
2270  NewTypeParm->removeDefaultArgument();
2271 
2272  // Merge default arguments for template type parameters.
2273  TemplateTypeParmDecl *OldTypeParm
2274  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2275  if (NewTypeParm->isParameterPack()) {
2276  assert(!NewTypeParm->hasDefaultArgument() &&
2277  "Parameter packs can't have a default argument!");
2278  SawParameterPack = true;
2279  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2280  NewTypeParm->hasDefaultArgument() &&
2281  (!SkipBody || !SkipBody->ShouldSkip)) {
2282  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2283  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2284  SawDefaultArgument = true;
2285  RedundantDefaultArg = true;
2286  PreviousDefaultArgLoc = NewDefaultLoc;
2287  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2288  // Merge the default argument from the old declaration to the
2289  // new declaration.
2290  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2291  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2292  } else if (NewTypeParm->hasDefaultArgument()) {
2293  SawDefaultArgument = true;
2294  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2295  } else if (SawDefaultArgument)
2296  MissingDefaultArg = true;
2297  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2298  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2299  // Check for unexpanded parameter packs.
2300  if (!NewNonTypeParm->isParameterPack() &&
2301  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2302  NewNonTypeParm->getTypeSourceInfo(),
2303  UPPC_NonTypeTemplateParameterType)) {
2304  Invalid = true;
2305  continue;
2306  }
2307 
2308  // Check the presence of a default argument here.
2309  if (NewNonTypeParm->hasDefaultArgument() &&
2311  NewNonTypeParm->getLocation(),
2312  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2313  NewNonTypeParm->removeDefaultArgument();
2314  }
2315 
2316  // Merge default arguments for non-type template parameters
2317  NonTypeTemplateParmDecl *OldNonTypeParm
2318  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2319  if (NewNonTypeParm->isParameterPack()) {
2320  assert(!NewNonTypeParm->hasDefaultArgument() &&
2321  "Parameter packs can't have a default argument!");
2322  if (!NewNonTypeParm->isPackExpansion())
2323  SawParameterPack = true;
2324  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2325  NewNonTypeParm->hasDefaultArgument() &&
2326  (!SkipBody || !SkipBody->ShouldSkip)) {
2327  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2328  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2329  SawDefaultArgument = true;
2330  RedundantDefaultArg = true;
2331  PreviousDefaultArgLoc = NewDefaultLoc;
2332  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2333  // Merge the default argument from the old declaration to the
2334  // new declaration.
2335  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2336  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2337  } else if (NewNonTypeParm->hasDefaultArgument()) {
2338  SawDefaultArgument = true;
2339  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2340  } else if (SawDefaultArgument)
2341  MissingDefaultArg = true;
2342  } else {
2343  TemplateTemplateParmDecl *NewTemplateParm
2344  = cast<TemplateTemplateParmDecl>(*NewParam);
2345 
2346  // Check for unexpanded parameter packs, recursively.
2347  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2348  Invalid = true;
2349  continue;
2350  }
2351 
2352  // Check the presence of a default argument here.
2353  if (NewTemplateParm->hasDefaultArgument() &&
2355  NewTemplateParm->getLocation(),
2356  NewTemplateParm->getDefaultArgument().getSourceRange()))
2357  NewTemplateParm->removeDefaultArgument();
2358 
2359  // Merge default arguments for template template parameters
2360  TemplateTemplateParmDecl *OldTemplateParm
2361  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2362  if (NewTemplateParm->isParameterPack()) {
2363  assert(!NewTemplateParm->hasDefaultArgument() &&
2364  "Parameter packs can't have a default argument!");
2365  if (!NewTemplateParm->isPackExpansion())
2366  SawParameterPack = true;
2367  } else if (OldTemplateParm &&
2368  hasVisibleDefaultArgument(OldTemplateParm) &&
2369  NewTemplateParm->hasDefaultArgument() &&
2370  (!SkipBody || !SkipBody->ShouldSkip)) {
2371  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2372  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2373  SawDefaultArgument = true;
2374  RedundantDefaultArg = true;
2375  PreviousDefaultArgLoc = NewDefaultLoc;
2376  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2377  // Merge the default argument from the old declaration to the
2378  // new declaration.
2379  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2380  PreviousDefaultArgLoc
2381  = OldTemplateParm->getDefaultArgument().getLocation();
2382  } else if (NewTemplateParm->hasDefaultArgument()) {
2383  SawDefaultArgument = true;
2384  PreviousDefaultArgLoc
2385  = NewTemplateParm->getDefaultArgument().getLocation();
2386  } else if (SawDefaultArgument)
2387  MissingDefaultArg = true;
2388  }
2389 
2390  // C++11 [temp.param]p11:
2391  // If a template parameter of a primary class template or alias template
2392  // is a template parameter pack, it shall be the last template parameter.
2393  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2394  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2395  TPC == TPC_TypeAliasTemplate)) {
2396  Diag((*NewParam)->getLocation(),
2397  diag::err_template_param_pack_must_be_last_template_parameter);
2398  Invalid = true;
2399  }
2400 
2401  if (RedundantDefaultArg) {
2402  // C++ [temp.param]p12:
2403  // A template-parameter shall not be given default arguments
2404  // by two different declarations in the same scope.
2405  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2406  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2407  Invalid = true;
2408  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2409  // C++ [temp.param]p11:
2410  // If a template-parameter of a class template has a default
2411  // template-argument, each subsequent template-parameter shall either
2412  // have a default template-argument supplied or be a template parameter
2413  // pack.
2414  Diag((*NewParam)->getLocation(),
2415  diag::err_template_param_default_arg_missing);
2416  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2417  Invalid = true;
2418  RemoveDefaultArguments = true;
2419  }
2420 
2421  // If we have an old template parameter list that we're merging
2422  // in, move on to the next parameter.
2423  if (OldParams)
2424  ++OldParam;
2425  }
2426 
2427  // We were missing some default arguments at the end of the list, so remove
2428  // all of the default arguments.
2429  if (RemoveDefaultArguments) {
2430  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2431  NewParamEnd = NewParams->end();
2432  NewParam != NewParamEnd; ++NewParam) {
2433  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2434  TTP->removeDefaultArgument();
2435  else if (NonTypeTemplateParmDecl *NTTP
2436  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2437  NTTP->removeDefaultArgument();
2438  else
2439  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2440  }
2441  }
2442 
2443  return Invalid;
2444 }
2445 
2446 namespace {
2447 
2448 /// A class which looks for a use of a certain level of template
2449 /// parameter.
2450 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2452 
2453  unsigned Depth;
2454 
2455  // Whether we're looking for a use of a template parameter that makes the
2456  // overall construct type-dependent / a dependent type. This is strictly
2457  // best-effort for now; we may fail to match at all for a dependent type
2458  // in some cases if this is set.
2459  bool IgnoreNonTypeDependent;
2460 
2461  bool Match;
2462  SourceLocation MatchLoc;
2463 
2464  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2465  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2466  Match(false) {}
2467 
2468  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2469  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2470  NamedDecl *ND = Params->getParam(0);
2471  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2472  Depth = PD->getDepth();
2473  } else if (NonTypeTemplateParmDecl *PD =
2474  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2475  Depth = PD->getDepth();
2476  } else {
2477  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2478  }
2479  }
2480 
2481  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2482  if (ParmDepth >= Depth) {
2483  Match = true;
2484  MatchLoc = Loc;
2485  return true;
2486  }
2487  return false;
2488  }
2489 
2490  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2491  // Prune out non-type-dependent expressions if requested. This can
2492  // sometimes result in us failing to find a template parameter reference
2493  // (if a value-dependent expression creates a dependent type), but this
2494  // mode is best-effort only.
2495  if (auto *E = dyn_cast_or_null<Expr>(S))
2496  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2497  return true;
2498  return super::TraverseStmt(S, Q);
2499  }
2500 
2501  bool TraverseTypeLoc(TypeLoc TL) {
2502  if (IgnoreNonTypeDependent && !TL.isNull() &&
2503  !TL.getType()->isDependentType())
2504  return true;
2505  return super::TraverseTypeLoc(TL);
2506  }
2507 
2508  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2509  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2510  }
2511 
2512  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2513  // For a best-effort search, keep looking until we find a location.
2514  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2515  }
2516 
2517  bool TraverseTemplateName(TemplateName N) {
2518  if (TemplateTemplateParmDecl *PD =
2519  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2520  if (Matches(PD->getDepth()))
2521  return false;
2522  return super::TraverseTemplateName(N);
2523  }
2524 
2525  bool VisitDeclRefExpr(DeclRefExpr *E) {
2526  if (NonTypeTemplateParmDecl *PD =
2527  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2528  if (Matches(PD->getDepth(), E->getExprLoc()))
2529  return false;
2530  return super::VisitDeclRefExpr(E);
2531  }
2532 
2533  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2534  return TraverseType(T->getReplacementType());
2535  }
2536 
2537  bool
2538  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2539  return TraverseTemplateArgument(T->getArgumentPack());
2540  }
2541 
2542  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2543  return TraverseType(T->getInjectedSpecializationType());
2544  }
2545 };
2546 } // end anonymous namespace
2547 
2548 /// Determines whether a given type depends on the given parameter
2549 /// list.
2550 static bool
2552  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2553  Checker.TraverseType(T);
2554  return Checker.Match;
2555 }
2556 
2557 // Find the source range corresponding to the named type in the given
2558 // nested-name-specifier, if any.
2560  QualType T,
2561  const CXXScopeSpec &SS) {
2563  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2564  if (const Type *CurType = NNS->getAsType()) {
2565  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2566  return NNSLoc.getTypeLoc().getSourceRange();
2567  } else
2568  break;
2569 
2570  NNSLoc = NNSLoc.getPrefix();
2571  }
2572 
2573  return SourceRange();
2574 }
2575 
2576 /// Match the given template parameter lists to the given scope
2577 /// specifier, returning the template parameter list that applies to the
2578 /// name.
2579 ///
2580 /// \param DeclStartLoc the start of the declaration that has a scope
2581 /// specifier or a template parameter list.
2582 ///
2583 /// \param DeclLoc The location of the declaration itself.
2584 ///
2585 /// \param SS the scope specifier that will be matched to the given template
2586 /// parameter lists. This scope specifier precedes a qualified name that is
2587 /// being declared.
2588 ///
2589 /// \param TemplateId The template-id following the scope specifier, if there
2590 /// is one. Used to check for a missing 'template<>'.
2591 ///
2592 /// \param ParamLists the template parameter lists, from the outermost to the
2593 /// innermost template parameter lists.
2594 ///
2595 /// \param IsFriend Whether to apply the slightly different rules for
2596 /// matching template parameters to scope specifiers in friend
2597 /// declarations.
2598 ///
2599 /// \param IsMemberSpecialization will be set true if the scope specifier
2600 /// denotes a fully-specialized type, and therefore this is a declaration of
2601 /// a member specialization.
2602 ///
2603 /// \returns the template parameter list, if any, that corresponds to the
2604 /// name that is preceded by the scope specifier @p SS. This template
2605 /// parameter list may have template parameters (if we're declaring a
2606 /// template) or may have no template parameters (if we're declaring a
2607 /// template specialization), or may be NULL (if what we're declaring isn't
2608 /// itself a template).
2610  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
2611  TemplateIdAnnotation *TemplateId,
2612  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
2613  bool &IsMemberSpecialization, bool &Invalid) {
2614  IsMemberSpecialization = false;
2615  Invalid = false;
2616 
2617  // The sequence of nested types to which we will match up the template
2618  // parameter lists. We first build this list by starting with the type named
2619  // by the nested-name-specifier and walking out until we run out of types.
2620  SmallVector<QualType, 4> NestedTypes;
2621  QualType T;
2622  if (SS.getScopeRep()) {
2623  if (CXXRecordDecl *Record
2624  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
2625  T = Context.getTypeDeclType(Record);
2626  else
2627  T = QualType(SS.getScopeRep()->getAsType(), 0);
2628  }
2629 
2630  // If we found an explicit specialization that prevents us from needing
2631  // 'template<>' headers, this will be set to the location of that
2632  // explicit specialization.
2633  SourceLocation ExplicitSpecLoc;
2634 
2635  while (!T.isNull()) {
2636  NestedTypes.push_back(T);
2637 
2638  // Retrieve the parent of a record type.
2639  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2640  // If this type is an explicit specialization, we're done.
2642  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2643  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
2644  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
2645  ExplicitSpecLoc = Spec->getLocation();
2646  break;
2647  }
2648  } else if (Record->getTemplateSpecializationKind()
2650  ExplicitSpecLoc = Record->getLocation();
2651  break;
2652  }
2653 
2654  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
2655  T = Context.getTypeDeclType(Parent);
2656  else
2657  T = QualType();
2658  continue;
2659  }
2660 
2661  if (const TemplateSpecializationType *TST
2663  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2664  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
2665  T = Context.getTypeDeclType(Parent);
2666  else
2667  T = QualType();
2668  continue;
2669  }
2670  }
2671 
2672  // Look one step prior in a dependent template specialization type.
2673  if (const DependentTemplateSpecializationType *DependentTST
2675  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
2676  T = QualType(NNS->getAsType(), 0);
2677  else
2678  T = QualType();
2679  continue;
2680  }
2681 
2682  // Look one step prior in a dependent name type.
2683  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
2684  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
2685  T = QualType(NNS->getAsType(), 0);
2686  else
2687  T = QualType();
2688  continue;
2689  }
2690 
2691  // Retrieve the parent of an enumeration type.
2692  if (const EnumType *EnumT = T->getAs<EnumType>()) {
2693  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
2694  // check here.
2695  EnumDecl *Enum = EnumT->getDecl();
2696 
2697  // Get to the parent type.
2698  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
2699  T = Context.getTypeDeclType(Parent);
2700  else
2701  T = QualType();
2702  continue;
2703  }
2704 
2705  T = QualType();
2706  }
2707  // Reverse the nested types list, since we want to traverse from the outermost
2708  // to the innermost while checking template-parameter-lists.
2709  std::reverse(NestedTypes.begin(), NestedTypes.end());
2710 
2711  // C++0x [temp.expl.spec]p17:
2712  // A member or a member template may be nested within many
2713  // enclosing class templates. In an explicit specialization for
2714  // such a member, the member declaration shall be preceded by a
2715  // template<> for each enclosing class template that is
2716  // explicitly specialized.
2717  bool SawNonEmptyTemplateParameterList = false;
2718 
2719  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
2720  if (SawNonEmptyTemplateParameterList) {
2721  Diag(DeclLoc, diag::err_specialize_member_of_template)
2722  << !Recovery << Range;
2723  Invalid = true;
2724  IsMemberSpecialization = false;
2725  return true;
2726  }
2727 
2728  return false;
2729  };
2730 
2731  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
2732  // Check that we can have an explicit specialization here.
2733  if (CheckExplicitSpecialization(Range, true))
2734  return true;
2735 
2736  // We don't have a template header, but we should.
2737  SourceLocation ExpectedTemplateLoc;
2738  if (!ParamLists.empty())
2739  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
2740  else
2741  ExpectedTemplateLoc = DeclStartLoc;
2742 
2743  Diag(DeclLoc, diag::err_template_spec_needs_header)
2744  << Range
2745  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
2746  return false;
2747  };
2748 
2749  unsigned ParamIdx = 0;
2750  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
2751  ++TypeIdx) {
2752  T = NestedTypes[TypeIdx];
2753 
2754  // Whether we expect a 'template<>' header.
2755  bool NeedEmptyTemplateHeader = false;
2756 
2757  // Whether we expect a template header with parameters.
2758  bool NeedNonemptyTemplateHeader = false;
2759 
2760  // For a dependent type, the set of template parameters that we
2761  // expect to see.
2762  TemplateParameterList *ExpectedTemplateParams = nullptr;
2763 
2764  // C++0x [temp.expl.spec]p15:
2765  // A member or a member template may be nested within many enclosing
2766  // class templates. In an explicit specialization for such a member, the
2767  // member declaration shall be preceded by a template<> for each
2768  // enclosing class template that is explicitly specialized.
2769  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2771  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
2772  ExpectedTemplateParams = Partial->getTemplateParameters();
2773  NeedNonemptyTemplateHeader = true;
2774  } else if (Record->isDependentType()) {
2775  if (Record->getDescribedClassTemplate()) {
2776  ExpectedTemplateParams = Record->getDescribedClassTemplate()
2777  ->getTemplateParameters();
2778  NeedNonemptyTemplateHeader = true;
2779  }
2780  } else if (ClassTemplateSpecializationDecl *Spec
2781  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2782  // C++0x [temp.expl.spec]p4:
2783  // Members of an explicitly specialized class template are defined
2784  // in the same manner as members of normal classes, and not using
2785  // the template<> syntax.
2786  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
2787  NeedEmptyTemplateHeader = true;
2788  else
2789  continue;
2790  } else if (Record->getTemplateSpecializationKind()) {
2791  if (Record->getTemplateSpecializationKind()
2793  TypeIdx == NumTypes - 1)
2794  IsMemberSpecialization = true;
2795 
2796  continue;
2797  }
2798  } else if (const TemplateSpecializationType *TST
2800  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2801  ExpectedTemplateParams = Template->getTemplateParameters();
2802  NeedNonemptyTemplateHeader = true;
2803  }
2804  } else if (T->getAs<DependentTemplateSpecializationType>()) {
2805  // FIXME: We actually could/should check the template arguments here
2806  // against the corresponding template parameter list.
2807  NeedNonemptyTemplateHeader = false;
2808  }
2809 
2810  // C++ [temp.expl.spec]p16:
2811  // In an explicit specialization declaration for a member of a class
2812  // template or a member template that ap- pears in namespace scope, the
2813  // member template and some of its enclosing class templates may remain
2814  // unspecialized, except that the declaration shall not explicitly
2815  // specialize a class member template if its en- closing class templates
2816  // are not explicitly specialized as well.
2817  if (ParamIdx < ParamLists.size()) {
2818  if (ParamLists[ParamIdx]->size() == 0) {
2819  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2820  false))
2821  return nullptr;
2822  } else
2823  SawNonEmptyTemplateParameterList = true;
2824  }
2825 
2826  if (NeedEmptyTemplateHeader) {
2827  // If we're on the last of the types, and we need a 'template<>' header
2828  // here, then it's a member specialization.
2829  if (TypeIdx == NumTypes - 1)
2830  IsMemberSpecialization = true;
2831 
2832  if (ParamIdx < ParamLists.size()) {
2833  if (ParamLists[ParamIdx]->size() > 0) {
2834  // The header has template parameters when it shouldn't. Complain.
2835  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2836  diag::err_template_param_list_matches_nontemplate)
2837  << T
2838  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
2839  ParamLists[ParamIdx]->getRAngleLoc())
2840  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2841  Invalid = true;
2842  return nullptr;
2843  }
2844 
2845  // Consume this template header.
2846  ++ParamIdx;
2847  continue;
2848  }
2849 
2850  if (!IsFriend)
2851  if (DiagnoseMissingExplicitSpecialization(
2852  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
2853  return nullptr;
2854 
2855  continue;
2856  }
2857 
2858  if (NeedNonemptyTemplateHeader) {
2859  // In friend declarations we can have template-ids which don't
2860  // depend on the corresponding template parameter lists. But
2861  // assume that empty parameter lists are supposed to match this
2862  // template-id.
2863  if (IsFriend && T->isDependentType()) {
2864  if (ParamIdx < ParamLists.size() &&
2865  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
2866  ExpectedTemplateParams = nullptr;
2867  else
2868  continue;
2869  }
2870 
2871  if (ParamIdx < ParamLists.size()) {
2872  // Check the template parameter list, if we can.
2873  if (ExpectedTemplateParams &&
2874  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
2875  ExpectedTemplateParams,
2876  true, TPL_TemplateMatch))
2877  Invalid = true;
2878 
2879  if (!Invalid &&
2880  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
2881  TPC_ClassTemplateMember))
2882  Invalid = true;
2883 
2884  ++ParamIdx;
2885  continue;
2886  }
2887 
2888  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
2889  << T
2890  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2891  Invalid = true;
2892  continue;
2893  }
2894  }
2895 
2896  // If there were at least as many template-ids as there were template
2897  // parameter lists, then there are no template parameter lists remaining for
2898  // the declaration itself.
2899  if (ParamIdx >= ParamLists.size()) {
2900  if (TemplateId && !IsFriend) {
2901  // We don't have a template header for the declaration itself, but we
2902  // should.
2903  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
2904  TemplateId->RAngleLoc));
2905 
2906  // Fabricate an empty template parameter list for the invented header.
2908  SourceLocation(), None,
2909  SourceLocation(), nullptr);
2910  }
2911 
2912  return nullptr;
2913  }
2914 
2915  // If there were too many template parameter lists, complain about that now.
2916  if (ParamIdx < ParamLists.size() - 1) {
2917  bool HasAnyExplicitSpecHeader = false;
2918  bool AllExplicitSpecHeaders = true;
2919  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
2920  if (ParamLists[I]->size() == 0)
2921  HasAnyExplicitSpecHeader = true;
2922  else
2923  AllExplicitSpecHeaders = false;
2924  }
2925 
2926  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2927  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
2928  : diag::err_template_spec_extra_headers)
2929  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
2930  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
2931 
2932  // If there was a specialization somewhere, such that 'template<>' is
2933  // not required, and there were any 'template<>' headers, note where the
2934  // specialization occurred.
2935  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
2936  Diag(ExplicitSpecLoc,
2937  diag::note_explicit_template_spec_does_not_need_header)
2938  << NestedTypes.back();
2939 
2940  // We have a template parameter list with no corresponding scope, which
2941  // means that the resulting template declaration can't be instantiated
2942  // properly (we'll end up with dependent nodes when we shouldn't).
2943  if (!AllExplicitSpecHeaders)
2944  Invalid = true;
2945  }
2946 
2947  // C++ [temp.expl.spec]p16:
2948  // In an explicit specialization declaration for a member of a class
2949  // template or a member template that ap- pears in namespace scope, the
2950  // member template and some of its enclosing class templates may remain
2951  // unspecialized, except that the declaration shall not explicitly
2952  // specialize a class member template if its en- closing class templates
2953  // are not explicitly specialized as well.
2954  if (ParamLists.back()->size() == 0 &&
2955  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2956  false))
2957  return nullptr;
2958 
2959  // Return the last template parameter list, which corresponds to the
2960  // entity being declared.
2961  return ParamLists.back();
2962 }
2963 
2965  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
2966  Diag(Template->getLocation(), diag::note_template_declared_here)
2967  << (isa<FunctionTemplateDecl>(Template)
2968  ? 0
2969  : isa<ClassTemplateDecl>(Template)
2970  ? 1
2971  : isa<VarTemplateDecl>(Template)
2972  ? 2
2973  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
2974  << Template->getDeclName();
2975  return;
2976  }
2977 
2979  for (OverloadedTemplateStorage::iterator I = OST->begin(),
2980  IEnd = OST->end();
2981  I != IEnd; ++I)
2982  Diag((*I)->getLocation(), diag::note_template_declared_here)
2983  << 0 << (*I)->getDeclName();
2984 
2985  return;
2986  }
2987 }
2988 
2989 static QualType
2991  const SmallVectorImpl<TemplateArgument> &Converted,
2992  SourceLocation TemplateLoc,
2993  TemplateArgumentListInfo &TemplateArgs) {
2994  ASTContext &Context = SemaRef.getASTContext();
2995  switch (BTD->getBuiltinTemplateKind()) {
2996  case BTK__make_integer_seq: {
2997  // Specializations of __make_integer_seq<S, T, N> are treated like
2998  // S<T, 0, ..., N-1>.
2999 
3000  // C++14 [inteseq.intseq]p1:
3001  // T shall be an integer type.
3002  if (!Converted[1].getAsType()->isIntegralType(Context)) {
3003  SemaRef.Diag(TemplateArgs[1].getLocation(),
3004  diag::err_integer_sequence_integral_element_type);
3005  return QualType();
3006  }
3007 
3008  // C++14 [inteseq.make]p1:
3009  // If N is negative the program is ill-formed.
3010  TemplateArgument NumArgsArg = Converted[2];
3011  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
3012  if (NumArgs < 0) {
3013  SemaRef.Diag(TemplateArgs[2].getLocation(),
3014  diag::err_integer_sequence_negative_length);
3015  return QualType();
3016  }
3017 
3018  QualType ArgTy = NumArgsArg.getIntegralType();
3019  TemplateArgumentListInfo SyntheticTemplateArgs;
3020  // The type argument gets reused as the first template argument in the
3021  // synthetic template argument list.
3022  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
3023  // Expand N into 0 ... N-1.
3024  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
3025  I < NumArgs; ++I) {
3026  TemplateArgument TA(Context, I, ArgTy);
3027  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
3028  TA, ArgTy, TemplateArgs[2].getLocation()));
3029  }
3030  // The first template argument will be reused as the template decl that
3031  // our synthetic template arguments will be applied to.
3032  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
3033  TemplateLoc, SyntheticTemplateArgs);
3034  }
3035 
3037  // Specializations of
3038  // __type_pack_element<Index, T_1, ..., T_N>
3039  // are treated like T_Index.
3040  assert(Converted.size() == 2 &&
3041  "__type_pack_element should be given an index and a parameter pack");
3042 
3043  // If the Index is out of bounds, the program is ill-formed.
3044  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
3045  llvm::APSInt Index = IndexArg.getAsIntegral();
3046  assert(Index >= 0 && "the index used with __type_pack_element should be of "
3047  "type std::size_t, and hence be non-negative");
3048  if (Index >= Ts.pack_size()) {
3049  SemaRef.Diag(TemplateArgs[0].getLocation(),
3050  diag::err_type_pack_element_out_of_bounds);
3051  return QualType();
3052  }
3053 
3054  // We simply return the type at index `Index`.
3055  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
3056  return Nth->getAsType();
3057  }
3058  llvm_unreachable("unexpected BuiltinTemplateDecl!");
3059 }
3060 
3061 /// Determine whether this alias template is "enable_if_t".
3062 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3063  return AliasTemplate->getName().equals("enable_if_t");
3064 }
3065 
3066 /// Collect all of the separable terms in the given condition, which
3067 /// might be a conjunction.
3068 ///
3069 /// FIXME: The right answer is to convert the logical expression into
3070 /// disjunctive normal form, so we can find the first failed term
3071 /// within each possible clause.
3072 static void collectConjunctionTerms(Expr *Clause,
3073  SmallVectorImpl<Expr *> &Terms) {
3074  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3075  if (BinOp->getOpcode() == BO_LAnd) {
3076  collectConjunctionTerms(BinOp->getLHS(), Terms);
3077  collectConjunctionTerms(BinOp->getRHS(), Terms);
3078  }
3079 
3080  return;
3081  }
3082 
3083  Terms.push_back(Clause);
3084 }
3085 
3086 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3087 // a left-hand side that is value-dependent but never true. Identify
3088 // the idiom and ignore that term.
3090  // Top-level '||'.
3091  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3092  if (!BinOp) return Cond;
3093 
3094  if (BinOp->getOpcode() != BO_LOr) return Cond;
3095 
3096  // With an inner '==' that has a literal on the right-hand side.
3097  Expr *LHS = BinOp->getLHS();
3098  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3099  if (!InnerBinOp) return Cond;
3100 
3101  if (InnerBinOp->getOpcode() != BO_EQ ||
3102  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3103  return Cond;
3104 
3105  // If the inner binary operation came from a macro expansion named
3106  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3107  // of the '||', which is the real, user-provided condition.
3108  SourceLocation Loc = InnerBinOp->getExprLoc();
3109  if (!Loc.isMacroID()) return Cond;
3110 
3111  StringRef MacroName = PP.getImmediateMacroName(Loc);
3112  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3113  return BinOp->getRHS();
3114 
3115  return Cond;
3116 }
3117 
3118 namespace {
3119 
3120 // A PrinterHelper that prints more helpful diagnostics for some sub-expressions
3121 // within failing boolean expression, such as substituting template parameters
3122 // for actual types.
3123 class FailedBooleanConditionPrinterHelper : public PrinterHelper {
3124 public:
3125  explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
3126  : Policy(P) {}
3127 
3128  bool handledStmt(Stmt *E, raw_ostream &OS) override {
3129  const auto *DR = dyn_cast<DeclRefExpr>(E);
3130  if (DR && DR->getQualifier()) {
3131  // If this is a qualified name, expand the template arguments in nested
3132  // qualifiers.
3133  DR->getQualifier()->print(OS, Policy, true);
3134  // Then print the decl itself.
3135  const ValueDecl *VD = DR->getDecl();
3136  OS << VD->getName();
3137  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3138  // This is a template variable, print the expanded template arguments.
3139  printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
3140  }
3141  return true;
3142  }
3143  return false;
3144  }
3145 
3146 private:
3147  const PrintingPolicy Policy;
3148 };
3149 
3150 } // end anonymous namespace
3151 
3152 std::pair<Expr *, std::string>
3154  Cond = lookThroughRangesV3Condition(PP, Cond);
3155 
3156  // Separate out all of the terms in a conjunction.
3157  SmallVector<Expr *, 4> Terms;
3158  collectConjunctionTerms(Cond, Terms);
3159 
3160  // Determine which term failed.
3161  Expr *FailedCond = nullptr;
3162  for (Expr *Term : Terms) {
3163  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3164 
3165  // Literals are uninteresting.
3166  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3167  isa<IntegerLiteral>(TermAsWritten))
3168  continue;
3169 
3170  // The initialization of the parameter from the argument is
3171  // a constant-evaluated context.
3172  EnterExpressionEvaluationContext ConstantEvaluated(
3174 
3175  bool Succeeded;
3176  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3177  !Succeeded) {
3178  FailedCond = TermAsWritten;
3179  break;
3180  }
3181  }
3182  if (!FailedCond)
3183  FailedCond = Cond->IgnoreParenImpCasts();
3184 
3185  std::string Description;
3186  {
3187  llvm::raw_string_ostream Out(Description);
3188  PrintingPolicy Policy = getPrintingPolicy();
3189  Policy.PrintCanonicalTypes = true;
3190  FailedBooleanConditionPrinterHelper Helper(Policy);
3191  FailedCond->printPretty(Out, &Helper, Policy, 0, "\n", nullptr);
3192  }
3193  return { FailedCond, Description };
3194 }
3195 
3197  SourceLocation TemplateLoc,
3198  TemplateArgumentListInfo &TemplateArgs) {
3201  if (DTN && DTN->isIdentifier())
3202  // When building a template-id where the template-name is dependent,
3203  // assume the template is a type template. Either our assumption is
3204  // correct, or the code is ill-formed and will be diagnosed when the
3205  // dependent name is substituted.
3207  DTN->getQualifier(),
3208  DTN->getIdentifier(),
3209  TemplateArgs);
3210 
3211  TemplateDecl *Template = Name.getAsTemplateDecl();
3212  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3213  isa<VarTemplateDecl>(Template) ||
3214  isa<ConceptDecl>(Template)) {
3215  // We might have a substituted template template parameter pack. If so,
3216  // build a template specialization type for it.
3218  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3219 
3220  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3221  << Name;
3222  NoteAllFoundTemplates(Name);
3223  return QualType();
3224  }
3225 
3226  // Check that the template argument list is well-formed for this
3227  // template.
3229  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3230  false, Converted))
3231  return QualType();
3232 
3233  QualType CanonType;
3234 
3235  bool InstantiationDependent = false;
3236  if (TypeAliasTemplateDecl *AliasTemplate =
3237  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3238  // Find the canonical type for this type alias template specialization.
3239  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3240  if (Pattern->isInvalidDecl())
3241  return QualType();
3242 
3244  Converted);
3245 
3246  // Only substitute for the innermost template argument list.
3247  MultiLevelTemplateArgumentList TemplateArgLists;
3248  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3249  unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
3250  for (unsigned I = 0; I < Depth; ++I)
3251  TemplateArgLists.addOuterTemplateArguments(None);
3252 
3254  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3255  if (Inst.isInvalid())
3256  return QualType();
3257 
3258  CanonType = SubstType(Pattern->getUnderlyingType(),
3259  TemplateArgLists, AliasTemplate->getLocation(),
3260  AliasTemplate->getDeclName());
3261  if (CanonType.isNull()) {
3262  // If this was enable_if and we failed to find the nested type
3263  // within enable_if in a SFINAE context, dig out the specific
3264  // enable_if condition that failed and present that instead.
3265  if (isEnableIfAliasTemplate(AliasTemplate)) {
3266  if (auto DeductionInfo = isSFINAEContext()) {
3267  if (*DeductionInfo &&
3268  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3269  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3270  diag::err_typename_nested_not_found_enable_if &&
3271  TemplateArgs[0].getArgument().getKind()
3273  Expr *FailedCond;
3274  std::string FailedDescription;
3275  std::tie(FailedCond, FailedDescription) =
3276  findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
3277 
3278  // Remove the old SFINAE diagnostic.
3279  PartialDiagnosticAt OldDiag =
3281  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3282 
3283  // Add a new SFINAE diagnostic specifying which condition
3284  // failed.
3285  (*DeductionInfo)->addSFINAEDiagnostic(
3286  OldDiag.first,
3287  PDiag(diag::err_typename_nested_not_found_requirement)
3288  << FailedDescription
3289  << FailedCond->getSourceRange());
3290  }
3291  }
3292  }
3293 
3294  return QualType();
3295  }
3296  } else if (Name.isDependent() ||
3298  TemplateArgs, InstantiationDependent)) {
3299  // This class template specialization is a dependent
3300  // type. Therefore, its canonical type is another class template
3301  // specialization type that contains all of the converted
3302  // arguments in canonical form. This ensures that, e.g., A<T> and
3303  // A<T, T> have identical types when A is declared as:
3304  //
3305  // template<typename T, typename U = T> struct A;
3306  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3307 
3308  // This might work out to be a current instantiation, in which
3309  // case the canonical type needs to be the InjectedClassNameType.
3310  //
3311  // TODO: in theory this could be a simple hashtable lookup; most
3312  // changes to CurContext don't change the set of current
3313  // instantiations.
3314  if (isa<ClassTemplateDecl>(Template)) {
3315  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3316  // If we get out to a namespace, we're done.
3317  if (Ctx->isFileContext()) break;
3318 
3319  // If this isn't a record, keep looking.
3320  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3321  if (!Record) continue;
3322 
3323  // Look for one of the two cases with InjectedClassNameTypes
3324  // and check whether it's the same template.
3325  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3326  !Record->getDescribedClassTemplate())
3327  continue;
3328 
3329  // Fetch the injected class name type and check whether its
3330  // injected type is equal to the type we just built.
3331  QualType ICNT = Context.getTypeDeclType(Record);
3332  QualType Injected = cast<InjectedClassNameType>(ICNT)
3333  ->getInjectedSpecializationType();
3334 
3335  if (CanonType != Injected->getCanonicalTypeInternal())
3336  continue;
3337 
3338  // If so, the canonical type of this TST is the injected
3339  // class name type of the record we just found.
3340  assert(ICNT.isCanonical());
3341  CanonType = ICNT;
3342  break;
3343  }
3344  }
3345  } else if (ClassTemplateDecl *ClassTemplate
3346  = dyn_cast<ClassTemplateDecl>(Template)) {
3347  // Find the class template specialization declaration that
3348  // corresponds to these arguments.
3349  void *InsertPos = nullptr;
3351  = ClassTemplate->findSpecialization(Converted, InsertPos);
3352  if (!Decl) {
3353  // This is the first time we have referenced this class template
3354  // specialization. Create the canonical declaration and add it to
3355  // the set of specializations.
3357  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3358  ClassTemplate->getDeclContext(),
3359  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3360  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3361  ClassTemplate->AddSpecialization(Decl, InsertPos);
3362  if (ClassTemplate->isOutOfLine())
3363  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3364  }
3365 
3366  if (Decl->getSpecializationKind() == TSK_Undeclared) {
3367  MultiLevelTemplateArgumentList TemplateArgLists;
3368  TemplateArgLists.addOuterTemplateArguments(Converted);
3369  InstantiateAttrsForDecl(TemplateArgLists, ClassTemplate->getTemplatedDecl(),
3370  Decl);
3371  }
3372 
3373  // Diagnose uses of this specialization.
3374  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3375 
3376  CanonType = Context.getTypeDeclType(Decl);
3377  assert(isa<RecordType>(CanonType) &&
3378  "type of non-dependent specialization is not a RecordType");
3379  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3380  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3381  TemplateArgs);
3382  }
3383 
3384  // Build the fully-sugared type for this class template
3385  // specialization, which refers back to the class template
3386  // specialization we created or found.
3387  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3388 }
3389 
3391  TemplateNameKind &TNK,
3392  SourceLocation NameLoc,
3393  IdentifierInfo *&II) {
3394  assert(TNK == TNK_Undeclared_template && "not an undeclared template name");
3395 
3396  TemplateName Name = ParsedName.get();
3397  auto *ATN = Name.getAsAssumedTemplateName();
3398  assert(ATN && "not an assumed template name");
3399  II = ATN->getDeclName().getAsIdentifierInfo();
3400 
3401  if (!resolveAssumedTemplateNameAsType(S, Name, NameLoc, /*Diagnose*/false)) {
3402  // Resolved to a type template name.
3403  ParsedName = TemplateTy::make(Name);
3404  TNK = TNK_Type_template;
3405  }
3406 }
3407 
3409  SourceLocation NameLoc,
3410  bool Diagnose) {
3411  // We assumed this undeclared identifier to be an (ADL-only) function
3412  // template name, but it was used in a context where a type was required.
3413  // Try to typo-correct it now.
3415  assert(ATN && "not an assumed template name");
3416 
3417  LookupResult R(*this, ATN->getDeclName(), NameLoc, LookupOrdinaryName);
3418  struct CandidateCallback : CorrectionCandidateCallback {
3419  bool ValidateCandidate(const TypoCorrection &TC) override {
3420  return TC.getCorrectionDecl() &&
3422  }
3423  std::unique_ptr<CorrectionCandidateCallback> clone() override {
3424  return std::make_unique<CandidateCallback>(*this);
3425  }
3426  } FilterCCC;
3427 
3428  TypoCorrection Corrected =
3429  CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
3430  FilterCCC, CTK_ErrorRecovery);
3431  if (Corrected && Corrected.getFoundDecl()) {
3432  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest)
3433  << ATN->getDeclName());
3434  Name = TemplateName(Corrected.getCorrectionDeclAs<TemplateDecl>());
3435  return false;
3436  }
3437 
3438  if (Diagnose)
3439  Diag(R.getNameLoc(), diag::err_no_template) << R.getLookupName();
3440  return true;
3441 }
3442 
3444  Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
3445  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3446  SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
3447  ASTTemplateArgsPtr TemplateArgsIn, SourceLocation RAngleLoc,
3448  bool IsCtorOrDtorName, bool IsClassName) {
3449  if (SS.isInvalid())
3450  return true;
3451 
3452  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3453  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3454 
3455  // C++ [temp.res]p3:
3456  // A qualified-id that refers to a type and in which the
3457  // nested-name-specifier depends on a template-parameter (14.6.2)
3458  // shall be prefixed by the keyword typename to indicate that the
3459  // qualified-id denotes a type, forming an
3460  // elaborated-type-specifier (7.1.5.3).
3461  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3462  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3463  << SS.getScopeRep() << TemplateII->getName();
3464  // Recover as if 'typename' were specified.
3465  // FIXME: This is not quite correct recovery as we don't transform SS
3466  // into the corresponding dependent form (and we don't diagnose missing
3467  // 'template' keywords within SS as a result).
3468  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3469  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3470  TemplateArgsIn, RAngleLoc);
3471  }
3472 
3473  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3474  // it's not actually allowed to be used as a type in most cases. Because
3475  // we annotate it before we know whether it's valid, we have to check for
3476  // this case here.
3477  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3478  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3479  Diag(TemplateIILoc,
3480  TemplateKWLoc.isInvalid()
3481  ? diag::err_out_of_line_qualified_id_type_names_constructor
3482  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3483  << TemplateII << 0 /*injected-class-name used as template name*/
3484  << 1 /*if any keyword was present, it was 'template'*/;
3485  }
3486  }
3487 
3488  TemplateName Template = TemplateD.get();
3489  if (Template.getAsAssumedTemplateName() &&
3490  resolveAssumedTemplateNameAsType(S, Template, TemplateIILoc))
3491  return true;
3492 
3493  // Translate the parser's template argument list in our AST format.
3494  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3495  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3496 
3497  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3498  QualType T
3500  DTN->getQualifier(),
3501  DTN->getIdentifier(),
3502  TemplateArgs);
3503  // Build type-source information.
3504  TypeLocBuilder TLB;
3508  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3509  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3510  SpecTL.setTemplateNameLoc(TemplateIILoc);
3511  SpecTL.setLAngleLoc(LAngleLoc);
3512  SpecTL.setRAngleLoc(RAngleLoc);
3513  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3514  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3515  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3516  }
3517 
3518  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3519  if (Result.isNull())
3520  return true;
3521 
3522  // Build type-source information.
3523  TypeLocBuilder TLB;
3525  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3526  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3527  SpecTL.setTemplateNameLoc(TemplateIILoc);
3528  SpecTL.setLAngleLoc(LAngleLoc);
3529  SpecTL.setRAngleLoc(RAngleLoc);
3530  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3531  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3532 
3533  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3534  // constructor or destructor name (in such a case, the scope specifier
3535  // will be attached to the enclosing Decl or Expr node).
3536  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3537  // Create an elaborated-type-specifier containing the nested-name-specifier.
3538  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3539  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3541  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3542  }
3543 
3544  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3545 }
3546 
3548  TypeSpecifierType TagSpec,
3549  SourceLocation TagLoc,
3550  CXXScopeSpec &SS,
3551  SourceLocation TemplateKWLoc,
3552  TemplateTy TemplateD,
3553  SourceLocation TemplateLoc,
3554  SourceLocation LAngleLoc,
3555  ASTTemplateArgsPtr TemplateArgsIn,
3556  SourceLocation RAngleLoc) {
3557  TemplateName Template = TemplateD.get();
3558 
3559  // Translate the parser's template argument list in our AST format.
3560  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3561  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3562 
3563  // Determine the tag kind
3565  ElaboratedTypeKeyword Keyword
3567 
3568  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3570  DTN->getQualifier(),
3571  DTN->getIdentifier(),
3572  TemplateArgs);
3573 
3574  // Build type-source information.
3575  TypeLocBuilder TLB;
3578  SpecTL.setElaboratedKeywordLoc(TagLoc);
3579  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3580  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3581  SpecTL.setTemplateNameLoc(TemplateLoc);
3582  SpecTL.setLAngleLoc(LAngleLoc);
3583  SpecTL.setRAngleLoc(RAngleLoc);
3584  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3585  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3586  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3587  }
3588 
3589  if (TypeAliasTemplateDecl *TAT =
3590  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
3591  // C++0x [dcl.type.elab]p2:
3592  // If the identifier resolves to a typedef-name or the simple-template-id
3593  // resolves to an alias template specialization, the
3594  // elaborated-type-specifier is ill-formed.
3595  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
3596  << TAT << NTK_TypeAliasTemplate << TagKind;
3597  Diag(TAT->getLocation(), diag::note_declared_at);
3598  }
3599 
3600  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
3601  if (Result.isNull())
3602  return TypeResult(true);
3603 
3604  // Check the tag kind
3605  if (const RecordType *RT = Result->getAs<RecordType>()) {
3606  RecordDecl *D = RT->getDecl();
3607 
3609  assert(Id && "templated class must have an identifier");
3610 
3611  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
3612  TagLoc, Id)) {
3613  Diag(TagLoc, diag::err_use_with_wrong_tag)
3614  << Result
3616  Diag(D->getLocation(), diag::note_previous_use);
3617  }
3618  }
3619 
3620  // Provide source-location information for the template specialization.
3621  TypeLocBuilder TLB;
3623  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3624  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3625  SpecTL.setTemplateNameLoc(TemplateLoc);
3626  SpecTL.setLAngleLoc(LAngleLoc);
3627  SpecTL.setRAngleLoc(RAngleLoc);
3628  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3629  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3630 
3631  // Construct an elaborated type containing the nested-name-specifier (if any)
3632  // and tag keyword.
3633  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
3634  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3635  ElabTL.setElaboratedKeywordLoc(TagLoc);
3636  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3637  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3638 }
3639 
3640 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
3641  NamedDecl *PrevDecl,
3642  SourceLocation Loc,
3644 
3646 
3648  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
3649  switch (Arg.getKind()) {
3656  return false;
3657 
3658  case TemplateArgument::Type: {
3659  QualType Type = Arg.getAsType();
3660  const TemplateTypeParmType *TPT =
3662  return TPT && !Type.hasQualifiers() &&
3663  TPT->getDepth() == Depth && TPT->getIndex() == Index;
3664  }
3665 
3667  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
3668  if (!DRE || !DRE->getDecl())
3669  return false;
3670  const NonTypeTemplateParmDecl *NTTP =
3671  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
3672  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
3673  }
3674 
3676  const TemplateTemplateParmDecl *TTP =
3677  dyn_cast_or_null<TemplateTemplateParmDecl>(
3679  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
3680  }
3681  llvm_unreachable("unexpected kind of template argument");
3682 }
3683 
3686  if (Params->size() != Args.size())
3687  return false;
3688 
3689  unsigned Depth = Params->getDepth();
3690 
3691  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
3692  TemplateArgument Arg = Args[I];
3693 
3694  // If the parameter is a pack expansion, the argument must be a pack
3695  // whose only element is a pack expansion.
3696  if (Params->getParam(I)->isParameterPack()) {
3697  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
3698  !Arg.pack_begin()->isPackExpansion())
3699  return false;
3700  Arg = Arg.pack_begin()->getPackExpansionPattern();
3701  }
3702 
3703  if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
3704  return false;
3705  }
3706 
3707  return true;
3708 }
3709 
3710 /// Convert the parser's template argument list representation into our form.
3713  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
3714  TemplateId.RAngleLoc);
3715  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
3716  TemplateId.NumArgs);
3717  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
3718  return TemplateArgs;
3719 }
3720 
3721 template<typename PartialSpecDecl>
3722 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
3723  if (Partial->getDeclContext()->isDependentContext())
3724  return;
3725 
3726  // FIXME: Get the TDK from deduction in order to provide better diagnostics
3727  // for non-substitution-failure issues?
3728  TemplateDeductionInfo Info(Partial->getLocation());
3729  if (S.isMoreSpecializedThanPrimary(Partial, Info))
3730  return;
3731 
3732  auto *Template = Partial->getSpecializedTemplate();
3733  S.Diag(Partial->getLocation(),
3734  diag::ext_partial_spec_not_more_specialized_than_primary)
3735  << isa<VarTemplateDecl>(Template);
3736 
3737  if (Info.hasSFINAEDiagnostic()) {
3740  Info.takeSFINAEDiagnostic(Diag);
3741  SmallString<128> SFINAEArgString;
3742  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
3743  S.Diag(Diag.first,
3744  diag::note_partial_spec_not_more_specialized_than_primary)
3745  << SFINAEArgString;
3746  }
3747 
3748  S.Diag(Template->getLocation(), diag::note_template_decl_here);
3749 }
3750 
3751 static void
3753  const llvm::SmallBitVector &DeducibleParams) {
3754  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
3755  if (!DeducibleParams[I]) {
3756  NamedDecl *Param = TemplateParams->getParam(I);
3757  if (Param->getDeclName())
3758  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3759  << Param->getDeclName();
3760  else
3761  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3762  << "(anonymous)";
3763  }
3764  }
3765 }
3766 
3767 
3768 template<typename PartialSpecDecl>
3770  PartialSpecDecl *Partial) {
3771  // C++1z [temp.class.spec]p8: (DR1495)
3772  // - The specialization shall be more specialized than the primary
3773  // template (14.5.5.2).
3774  checkMoreSpecializedThanPrimary(S, Partial);
3775 
3776  // C++ [temp.class.spec]p8: (DR1315)
3777  // - Each template-parameter shall appear at least once in the
3778  // template-id outside a non-deduced context.
3779  // C++1z [temp.class.spec.match]p3 (P0127R2)
3780  // If the template arguments of a partial specialization cannot be
3781  // deduced because of the structure of its template-parameter-list
3782  // and the template-id, the program is ill-formed.
3783  auto *TemplateParams = Partial->getTemplateParameters();
3784  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3785  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
3786  TemplateParams->getDepth(), DeducibleParams);
3787 
3788  if (!DeducibleParams.all()) {
3789  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3790  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
3791  << isa<VarTemplatePartialSpecializationDecl>(Partial)
3792  << (NumNonDeducible > 1)
3793  << SourceRange(Partial->getLocation(),
3794  Partial->getTemplateArgsAsWritten()->RAngleLoc);
3795  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
3796  }
3797 }
3798 
3801  checkTemplatePartialSpecialization(*this, Partial);
3802 }
3803 
3806  checkTemplatePartialSpecialization(*this, Partial);
3807 }
3808 
3810  // C++1z [temp.param]p11:
3811  // A template parameter of a deduction guide template that does not have a
3812  // default-argument shall be deducible from the parameter-type-list of the
3813  // deduction guide template.
3814  auto *TemplateParams = TD->getTemplateParameters();
3815  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3816  MarkDeducedTemplateParameters(TD, DeducibleParams);
3817  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
3818  // A parameter pack is deducible (to an empty pack).
3819  auto *Param = TemplateParams->getParam(I);
3820  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
3821  DeducibleParams[I] = true;
3822  }
3823 
3824  if (!DeducibleParams.all()) {
3825  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3826  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
3827  << (NumNonDeducible > 1);
3828  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
3829  }
3830 }
3831 
3833  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
3834  TemplateParameterList *TemplateParams, StorageClass SC,
3835  bool IsPartialSpecialization) {
3836  // D must be variable template id.
3838  "Variable template specialization is declared with a template it.");
3839 
3840  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
3841  TemplateArgumentListInfo TemplateArgs =
3842  makeTemplateArgumentListInfo(*this, *TemplateId);
3843  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
3844  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
3845  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
3846 
3847  TemplateName Name = TemplateId->Template.get();
3848 
3849  // The template-id must name a variable template.
3850  VarTemplateDecl *VarTemplate =
3851  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
3852  if (!VarTemplate) {
3853  NamedDecl *FnTemplate;
3854  if (auto *OTS = Name.getAsOverloadedTemplate())
3855  FnTemplate = *OTS->begin();
3856  else
3857  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
3858  if (FnTemplate)
3859  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
3860  << FnTemplate->getDeclName();
3861  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
3862  << IsPartialSpecialization;
3863  }
3864 
3865  // Check for unexpanded parameter packs in any of the template arguments.
3866  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
3867  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
3868  UPPC_PartialSpecialization))
3869  return true;
3870 
3871  // Check that the template argument list is well-formed for this
3872  // template.
3874  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
3875  false, Converted))
3876  return true;
3877 
3878  // Find the variable template (partial) specialization declaration that
3879  // corresponds to these arguments.
3880  if (IsPartialSpecialization) {
3881  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
3882  TemplateArgs.size(), Converted))
3883  return true;
3884 
3885  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
3886  // also do them during instantiation.
3887  bool InstantiationDependent;
3888  if (!Name.isDependent() &&
3890  TemplateArgs.arguments(),
3891  InstantiationDependent)) {
3892  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
3893  << VarTemplate->getDeclName();
3894  IsPartialSpecialization = false;
3895  }
3896 
3898  Converted)) {
3899  // C++ [temp.class.spec]p9b3:
3900  //
3901  // -- The argument list of the specialization shall not be identical
3902  // to the implicit argument list of the primary template.
3903  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
3904  << /*variable template*/ 1
3905  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
3906  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
3907  // FIXME: Recover from this by treating the declaration as a redeclaration
3908  // of the primary template.
3909  return true;
3910  }
3911  }
3912 
3913  void *InsertPos = nullptr;
3914  VarTemplateSpecializationDecl *PrevDecl = nullptr;
3915 
3916  if (IsPartialSpecialization)
3917  // FIXME: Template parameter list matters too
3918  PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
3919  else
3920  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
3921 
3922  VarTemplateSpecializationDecl *Specialization = nullptr;
3923 
3924  // Check whether we can declare a variable template specialization in
3925  // the current scope.
3926  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
3927  TemplateNameLoc,
3928  IsPartialSpecialization))
3929  return true;
3930 
3931  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
3932  // Since the only prior variable template specialization with these
3933  // arguments was referenced but not declared, reuse that
3934  // declaration node as our own, updating its source location and
3935  // the list of outer template parameters to reflect our new declaration.
3936  Specialization = PrevDecl;
3937  Specialization->setLocation(TemplateNameLoc);
3938  PrevDecl = nullptr;
3939  } else if (IsPartialSpecialization) {
3940  // Create a new class template partial specialization declaration node.
3942  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
3945  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
3946  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
3947  Converted, TemplateArgs);
3948 
3949  if (!PrevPartial)
3950  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
3951  Specialization = Partial;
3952 
3953  // If we are providing an explicit specialization of a member variable
3954  // template specialization, make a note of that.
3955  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
3956  PrevPartial->setMemberSpecialization();
3957 
3958  CheckTemplatePartialSpecialization(Partial);
3959  } else {
3960  // Create a new class template specialization declaration node for
3961  // this explicit specialization or friend declaration.
3962  Specialization = VarTemplateSpecializationDecl::Create(
3963  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
3964  VarTemplate, DI->getType(), DI, SC, Converted);
3965  Specialization->setTemplateArgsInfo(TemplateArgs);
3966 
3967  if (!PrevDecl)
3968  VarTemplate->AddSpecialization(Specialization, InsertPos);
3969  }
3970 
3971  // C++ [temp.expl.spec]p6:
3972  // If a template, a member template or the member of a class template is
3973  // explicitly specialized then that specialization shall be declared
3974  // before the first use of that specialization that would cause an implicit
3975  // instantiation to take place, in every translation unit in which such a
3976  // use occurs; no diagnostic is required.
3977  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
3978  bool Okay = false;
3979  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
3980  // Is there any previous explicit specialization declaration?
3982  Okay = true;
3983  break;
3984  }
3985  }
3986 
3987  if (!Okay) {
3988  SourceRange Range(TemplateNameLoc, RAngleLoc);
3989  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
3990  << Name << Range;
3991 
3992  Diag(PrevDecl->getPointOfInstantiation(),
3993  diag::note_instantiation_required_here)
3994  << (PrevDecl->getTemplateSpecializationKind() !=
3996  return true;
3997  }
3998  }
3999 
4000  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
4001  Specialization->setLexicalDeclContext(CurContext);
4002 
4003  // Add the specialization into its lexical context, so that it can
4004  // be seen when iterating through the list of declarations in that
4005  // context. However, specializations are not found by name lookup.
4006  CurContext->addDecl(Specialization);
4007 
4008  // Note that this is an explicit specialization.
4010 
4011  if (PrevDecl) {
4012  // Check that this isn't a redefinition of this specialization,
4013  // merging with previous declarations.
4014  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
4015  forRedeclarationInCurContext());
4016  PrevSpec.addDecl(PrevDecl);
4017  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
4018  } else if (Specialization->isStaticDataMember() &&
4019  Specialization->isOutOfLine()) {
4020  Specialization->setAccess(VarTemplate->getAccess());
4021  }
4022 
4023  return Specialization;
4024 }
4025 
4026 namespace {
4027 /// A partial specialization whose template arguments have matched
4028 /// a given template-id.
4029 struct PartialSpecMatchResult {
4031  TemplateArgumentList *Args;
4032 };
4033 } // end anonymous namespace
4034 
4035 DeclResult
4037  SourceLocation TemplateNameLoc,
4038  const TemplateArgumentListInfo &TemplateArgs) {
4039  assert(Template && "A variable template id without template?");
4040 
4041  // Check that the template argument list is well-formed for this template.
4043  if (CheckTemplateArgumentList(
4044  Template, TemplateNameLoc,
4045  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
4046  Converted))
4047  return true;
4048 
4049  // Find the variable template specialization declaration that
4050  // corresponds to these arguments.
4051  void *InsertPos = nullptr;
4052  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
4053  Converted, InsertPos)) {
4054  checkSpecializationVisibility(TemplateNameLoc, Spec);
4055  // If we already have a variable template specialization, return it.
4056  return Spec;
4057  }
4058 
4059  // This is the first time we have referenced this variable template
4060  // specialization. Create the canonical declaration and add it to
4061  // the set of specializations, based on the closest partial specialization
4062  // that it represents. That is,
4063  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
4065  Converted);
4066  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
4067  bool AmbiguousPartialSpec = false;
4068  typedef PartialSpecMatchResult MatchResult;
4070  SourceLocation PointOfInstantiation = TemplateNameLoc;
4071  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
4072  /*ForTakingAddress=*/false);
4073 
4074  // 1. Attempt to find the closest partial specialization that this
4075  // specializes, if any.
4076  // If any of the template arguments is dependent, then this is probably
4077  // a placeholder for an incomplete declarative context; which must be
4078  // complete by instantiation time. Thus, do not search through the partial
4079  // specializations yet.
4080  // TODO: Unify with InstantiateClassTemplateSpecialization()?
4081  // Perhaps better after unification of DeduceTemplateArguments() and
4082  // getMoreSpecializedPartialSpecialization().
4083  bool InstantiationDependent = false;
4085  TemplateArgs, InstantiationDependent)) {
4086 
4088  Template->getPartialSpecializations(PartialSpecs);
4089 
4090  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
4091  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
4092  TemplateDeductionInfo Info(FailedCandidates.getLocation());
4093 
4094  if (TemplateDeductionResult Result =
4095  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
4096  // Store the failed-deduction information for use in diagnostics, later.
4097  // TODO: Actually use the failed-deduction info?
4098  FailedCandidates.addCandidate().set(
4099  DeclAccessPair::make(Template, AS_public), Partial,
4100  MakeDeductionFailureInfo(Context, Result, Info));
4101  (void)Result;
4102  } else {
4103  Matched.push_back(PartialSpecMatchResult());
4104  Matched.back().Partial = Partial;
4105  Matched.back().Args = Info.take();
4106  }
4107  }
4108 
4109  if (Matched.size() >= 1) {
4110  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
4111  if (Matched.size() == 1) {
4112  // -- If exactly one matching specialization is found, the
4113  // instantiation is generated from that specialization.
4114  // We don't need to do anything for this.
4115  } else {
4116  // -- If more than one matching specialization is found, the
4117  // partial order rules (14.5.4.2) are used to determine
4118  // whether one of the specializations is more specialized
4119  // than the others. If none of the specializations is more
4120  // specialized than all of the other matching
4121  // specializations, then the use of the variable template is
4122  // ambiguous and the program is ill-formed.
4123  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4124  PEnd = Matched.end();
4125  P != PEnd; ++P) {
4126  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4127  PointOfInstantiation) ==
4128  P->Partial)
4129  Best = P;
4130  }
4131 
4132  // Determine if the best partial specialization is more specialized than
4133  // the others.
4134  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4135  PEnd = Matched.end();
4136  P != PEnd; ++P) {
4137  if (P != Best && getMoreSpecializedPartialSpecialization(
4138  P->Partial, Best->Partial,
4139  PointOfInstantiation) != Best->Partial) {
4140  AmbiguousPartialSpec = true;
4141  break;
4142  }
4143  }
4144  }
4145 
4146  // Instantiate using the best variable template partial specialization.
4147  InstantiationPattern = Best->Partial;
4148  InstantiationArgs = Best->Args;
4149  } else {
4150  // -- If no match is found, the instantiation is generated
4151  // from the primary template.
4152  // InstantiationPattern = Template->getTemplatedDecl();
4153  }
4154  }
4155 
4156  // 2. Create the canonical declaration.
4157  // Note that we do not instantiate a definition until we see an odr-use
4158  // in DoMarkVarDeclReferenced().
4159  // FIXME: LateAttrs et al.?
4160  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4161  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4162  Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
4163  if (!Decl)
4164  return true;
4165 
4166  if (AmbiguousPartialSpec) {
4167  // Partial ordering did not produce a clear winner. Complain.
4168  Decl->setInvalidDecl();
4169  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4170  << Decl;
4171 
4172  // Print the matching partial specializations.
4173  for (MatchResult P : Matched)
4174  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4175  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4176  *P.Args);
4177  return true;
4178  }
4179 
4181  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4182  Decl->setInstantiationOf(D, InstantiationArgs);
4183 
4184  checkSpecializationVisibility(TemplateNameLoc, Decl);
4185 
4186  assert(Decl && "No variable template specialization?");
4187  return Decl;
4188 }
4189 
4190 ExprResult
4192  const DeclarationNameInfo &NameInfo,
4193  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4194  const TemplateArgumentListInfo *TemplateArgs) {
4195 
4196  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4197  *TemplateArgs);
4198  if (Decl.isInvalid())
4199  return ExprError();
4200 
4201  VarDecl *Var = cast<VarDecl>(Decl.get());
4202  if (!Var->getTemplateSpecializationKind())
4204  NameInfo.getLoc());
4205 
4206  // Build an ordinary singleton decl ref.
4207  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4208  /*FoundD=*/nullptr, TemplateArgs);
4209 }
4210 
4212  SourceLocation Loc) {
4213  Diag(Loc, diag::err_template_missing_args)
4214  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4215  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4216  Diag(TD->getLocation(), diag::note_template_decl_here)
4217  << TD->getTemplateParameters()->getSourceRange();
4218  }
4219 }
4220 
4221 ExprResult
4223  SourceLocation TemplateKWLoc,
4224  SourceLocation ConceptNameLoc,
4225  NamedDecl *FoundDecl,
4226  ConceptDecl *NamedConcept,
4227  const TemplateArgumentListInfo *TemplateArgs) {
4228  assert(NamedConcept && "A concept template id without a template?");
4229 
4231  if (CheckTemplateArgumentList(NamedConcept, ConceptNameLoc,
4232  const_cast<TemplateArgumentListInfo&>(*TemplateArgs),
4233  /*PartialTemplateArgs=*/false, Converted,
4234  /*UpdateArgsWithConversion=*/false))
4235  return ExprError();
4236 
4237  Optional<bool> IsSatisfied;
4238  bool AreArgsDependent = false;
4239  for (TemplateArgument &Arg : Converted) {
4240  if (Arg.isDependent()) {
4241  AreArgsDependent = true;
4242  break;
4243  }
4244  }
4245  if (!AreArgsDependent) {
4246  InstantiatingTemplate Inst(*this, ConceptNameLoc,
4247  InstantiatingTemplate::ConstraintsCheck{}, NamedConcept, Converted,
4248  SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameLoc,
4249  TemplateArgs->getRAngleLoc()));
4251  MLTAL.addOuterTemplateArguments(Converted);
4252  bool Satisfied;
4253  if (CalculateConstraintSatisfaction(NamedConcept, MLTAL,
4254  NamedConcept->getConstraintExpr(),
4255  Satisfied))
4256  return ExprError();
4257  IsSatisfied = Satisfied;
4258  }
4259  return ConceptSpecializationExpr::Create(Context,
4260  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
4261  TemplateKWLoc, ConceptNameLoc, FoundDecl, NamedConcept,
4262  ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
4263  IsSatisfied);
4264 }
4265 
4267  SourceLocation TemplateKWLoc,
4268  LookupResult &R,
4269  bool RequiresADL,
4270  const TemplateArgumentListInfo *TemplateArgs) {
4271  // FIXME: Can we do any checking at this point? I guess we could check the
4272  // template arguments that we have against the template name, if the template
4273  // name refers to a single template. That's not a terribly common case,
4274  // though.
4275  // foo<int> could identify a single function unambiguously
4276  // This approach does NOT work, since f<int>(1);
4277  // gets resolved prior to resorting to overload resolution
4278  // i.e., template<class T> void f(double);
4279  // vs template<class T, class U> void f(U);
4280 
4281  // These should be filtered out by our callers.
4282  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4283 
4284  // Non-function templates require a template argument list.
4285  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4286  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4287  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4288  return ExprError();
4289  }
4290  }
4291 
4292  auto AnyDependentArguments = [&]() -> bool {
4293  bool InstantiationDependent;
4294  return TemplateArgs &&
4296  *TemplateArgs, InstantiationDependent);
4297  };
4298 
4299  // In C++1y, check variable template ids.
4300  if (R.getAsSingle<VarTemplateDecl>() && !AnyDependentArguments()) {
4301  return CheckVarTemplateId(SS, R.getLookupNameInfo(),
4303  TemplateKWLoc, TemplateArgs);
4304  }
4305 
4306  if (R.getAsSingle<ConceptDecl>()) {
4307  return CheckConceptTemplateId(SS, TemplateKWLoc,
4309  R.getFoundDecl(),
4310  R.getAsSingle<ConceptDecl>(), TemplateArgs);
4311  }
4312 
4313  // We don't want lookup warnings at this point.
4314  R.suppressDiagnostics();
4315 
4318  SS.getWithLocInContext(Context),
4319  TemplateKWLoc,
4320  R.getLookupNameInfo(),
4321  RequiresADL, TemplateArgs,
4322  R.begin(), R.end());
4323 
4324  return ULE;
4325 }
4326 
4327 // We actually only call this from template instantiation.
4328 ExprResult
4330  SourceLocation TemplateKWLoc,
4331  const DeclarationNameInfo &NameInfo,
4332  const TemplateArgumentListInfo *TemplateArgs) {
4333 
4334  assert(TemplateArgs || TemplateKWLoc.isValid());
4335  DeclContext *DC;
4336  if (!(DC = computeDeclContext(SS, false)) ||
4337  DC->isDependentContext() ||
4338  RequireCompleteDeclContext(SS, DC))
4339  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4340 
4341  bool MemberOfUnknownSpecialization;
4342  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4343  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4344  /*Entering*/false, MemberOfUnknownSpecialization,
4345  TemplateKWLoc))
4346  return ExprError();
4347 
4348  if (R.isAmbiguous())
4349  return ExprError();
4350 
4351  if (R.empty()) {
4352  Diag(NameInfo.getLoc(), diag::err_no_member)
4353  << NameInfo.getName() << DC << SS.getRange();
4354  return ExprError();
4355  }
4356 
4357  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4358  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4359  << SS.getScopeRep()
4360  << NameInfo.getName().getAsString() << SS.getRange();
4361  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4362  return ExprError();
4363  }
4364 
4365  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4366 }
4367 
4368 /// Form a dependent template name.
4369 ///
4370 /// This action forms a dependent template name given the template
4371 /// name and its (presumably dependent) scope specifier. For
4372 /// example, given "MetaFun::template apply", the scope specifier \p
4373 /// SS will be "MetaFun::", \p TemplateKWLoc contains the location
4374 /// of the "template" keyword, and "apply" is the \p Name.
4376  CXXScopeSpec &SS,
4377  SourceLocation TemplateKWLoc,
4378  const UnqualifiedId &Name,
4379  ParsedType ObjectType,
4380  bool EnteringContext,
4381  TemplateTy &Result,
4382  bool AllowInjectedClassName) {
4383  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4384  Diag(TemplateKWLoc,
4385  getLangOpts().CPlusPlus11 ?
4386  diag::warn_cxx98_compat_template_outside_of_template :
4387  diag::ext_template_outside_of_template)
4388  << FixItHint::CreateRemoval(TemplateKWLoc);
4389 
4390  DeclContext *LookupCtx = nullptr;
4391  if (SS.isSet())
4392  LookupCtx = computeDeclContext(SS, EnteringContext);
4393  if (!LookupCtx && ObjectType)
4394  LookupCtx = computeDeclContext(ObjectType.get());
4395  if (LookupCtx) {
4396  // C++0x [temp.names]p5:
4397  // If a name prefixed by the keyword template is not the name of
4398  // a template, the program is ill-formed. [Note: the keyword
4399  // template may not be applied to non-template members of class
4400  // templates. -end note ] [ Note: as is the case with the
4401  // typename prefix, the template prefix is allowed in cases
4402  // where it is not strictly necessary; i.e., when the
4403  // nested-name-specifier or the expression on the left of the ->
4404  // or . is not dependent on a template-parameter, or the use
4405  // does not appear in the scope of a template. -end note]
4406  //
4407  // Note: C++03 was more strict here, because it banned the use of
4408  // the "template" keyword prior to a template-name that was not a
4409  // dependent name. C++ DR468 relaxed this requirement (the
4410  // "template" keyword is now permitted). We follow the C++0x
4411  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4412  bool MemberOfUnknownSpecialization;
4413  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4414  ObjectType, EnteringContext, Result,
4415  MemberOfUnknownSpecialization);
4416  if (TNK == TNK_Non_template && MemberOfUnknownSpecialization) {
4417  // This is a dependent template. Handle it below.
4418  } else if (TNK == TNK_Non_template) {
4419  // Do the lookup again to determine if this is a "nothing found" case or
4420  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4421  // need to do this.
4422  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4423  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4424  LookupOrdinaryName);
4425  bool MOUS;
4426  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext,
4427  MOUS, TemplateKWLoc) && !R.isAmbiguous())
4428  Diag(Name.getBeginLoc(), diag::err_no_member)
4429  << DNI.getName() << LookupCtx << SS.getRange();
4430  return TNK_Non_template;
4431  } else {
4432  // We found something; return it.
4433  auto *LookupRD = dyn_cast<CXXRecordDecl>(LookupCtx);
4434  if (!AllowInjectedClassName && SS.isSet() && LookupRD &&
4436  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4437  // C++14 [class.qual]p2:
4438  // In a lookup in which function names are not ignored and the
4439  // nested-name-specifier nominates a class C, if the name specified
4440  // [...] is the injected-class-name of C, [...] the name is instead
4441  // considered to name the constructor
4442  //
4443  // We don't get here if naming the constructor would be valid, so we
4444  // just reject immediately and recover by treating the
4445  // injected-class-name as naming the template.
4446  Diag(Name.getBeginLoc(),
4447  diag::ext_out_of_line_qualified_id_type_names_constructor)
4448  << Name.Identifier
4449  << 0 /*injected-class-name used as template name*/
4450  << 1 /*'template' keyword was used*/;
4451  }
4452  return TNK;
4453  }
4454  }
4455 
4456  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4457 
4458  switch (Name.getKind()) {
4460  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4461  Name.Identifier));
4463 
4465  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4467  return TNK_Function_template;
4468 
4470  llvm_unreachable("literal operator id cannot have a dependent scope");
4471 
4472  default:
4473  break;
4474  }
4475 
4476  Diag(Name.getBeginLoc(), diag::err_template_kw_refers_to_non_template)
4477  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4478  << TemplateKWLoc;
4479  return TNK_Non_template;
4480 }
4481 
4483  TemplateArgumentLoc &AL,
4484  SmallVectorImpl<TemplateArgument> &Converted) {
4485  const TemplateArgument &Arg = AL.getArgument();
4486  QualType ArgType;
4487  TypeSourceInfo *TSI = nullptr;
4488 
4489  // Check template type parameter.
4490  switch(Arg.getKind()) {
4492  // C++ [temp.arg.type]p1:
4493  // A template-argument for a template-parameter which is a
4494  // type shall be a type-id.
4495  ArgType = Arg.getAsType();
4496  TSI = AL.getTypeSourceInfo();
4497  break;
4500  // We have a template type parameter but the template argument
4501  // is a template without any arguments.
4502  SourceRange SR = AL.getSourceRange();
4504  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4505  return true;
4506  }
4508  // We have a template type parameter but the template argument is an
4509  // expression; see if maybe it is missing the "typename" keyword.
4510  CXXScopeSpec SS;
4511  DeclarationNameInfo NameInfo;
4512 
4513  if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
4514  SS.Adopt(ArgExpr->getQualifierLoc());
4515  NameInfo = ArgExpr->getNameInfo();
4516  } else if (DependentScopeDeclRefExpr *ArgExpr =
4517  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4518  SS.Adopt(ArgExpr->getQualifierLoc());
4519  NameInfo = ArgExpr->getNameInfo();
4520  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4521  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4522  if (ArgExpr->isImplicitAccess()) {
4523  SS.Adopt(ArgExpr->getQualifierLoc());
4524  NameInfo = ArgExpr->getMemberNameInfo();
4525  }
4526  }
4527 
4528  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4529  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4530  LookupParsedName(Result, CurScope, &SS);
4531 
4532  if (Result.getAsSingle<TypeDecl>() ||
4533  Result.getResultKind() ==
4535  // Suggest that the user add 'typename' before the NNS.
4536  SourceLocation Loc = AL.getSourceRange().getBegin();
4537  Diag(Loc, getLangOpts().MSVCCompat
4538  ? diag::ext_ms_template_type_arg_missing_typename
4539  : diag::err_template_arg_must_be_type_suggest)
4540  << FixItHint::CreateInsertion(Loc, "typename ");
4541  Diag(Param->getLocation(), diag::note_template_param_here);
4542 
4543  // Recover by synthesizing a type using the location information that we
4544  // already have.
4545  ArgType =
4546  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4547  TypeLocBuilder TLB;
4548  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4549  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4550  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4551  TL.setNameLoc(NameInfo.getLoc());
4552  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4553 
4554  // Overwrite our input TemplateArgumentLoc so that we can recover
4555  // properly.
4556  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
4558 
4559  break;
4560  }
4561  }
4562  // fallthrough
4563  LLVM_FALLTHROUGH;
4564  }
4565  default: {
4566  // We have a template type parameter but the template argument
4567  // is not a type.
4568  SourceRange SR = AL.getSourceRange();
4569  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
4570  Diag(Param->getLocation(), diag::note_template_param_here);
4571 
4572  return true;
4573  }
4574  }
4575 
4576  if (CheckTemplateArgument(Param, TSI))
4577  return true;
4578 
4579  // Add the converted template type argument.
4580  ArgType = Context.getCanonicalType(ArgType);
4581 
4582  // Objective-C ARC:
4583  // If an explicitly-specified template argument type is a lifetime type
4584  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
4585  if (getLangOpts().ObjCAutoRefCount &&
4586  ArgType->isObjCLifetimeType() &&
4587  !ArgType.getObjCLifetime()) {
4588  Qualifiers Qs;
4590  ArgType = Context.getQualifiedType(ArgType, Qs);
4591  }
4592 
4593  Converted.push_back(TemplateArgument(ArgType));
4594  return false;
4595 }
4596 
4597 /// Substitute template arguments into the default template argument for
4598 /// the given template type parameter.
4599 ///
4600 /// \param SemaRef the semantic analysis object for which we are performing
4601 /// the substitution.
4602 ///
4603 /// \param Template the template that we are synthesizing template arguments
4604 /// for.
4605 ///
4606 /// \param TemplateLoc the location of the template name that started the
4607 /// template-id we are checking.
4608 ///
4609 /// \param RAngleLoc the location of the right angle bracket ('>') that
4610 /// terminates the template-id.
4611 ///
4612 /// \param Param the template template parameter whose default we are
4613 /// substituting into.
4614 ///
4615 /// \param Converted the list of template arguments provided for template
4616 /// parameters that precede \p Param in the template parameter list.
4617 /// \returns the substituted template argument, or NULL if an error occurred.
4618 static TypeSourceInfo *
4620  TemplateDecl *Template,
4621  SourceLocation TemplateLoc,
4622  SourceLocation RAngleLoc,
4623  TemplateTypeParmDecl *Param,
4624  SmallVectorImpl<TemplateArgument> &Converted) {
4625  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
4626 
4627  // If the argument type is dependent, instantiate it now based
4628  // on the previously-computed template arguments.
4629  if (ArgType->getType()->isInstantiationDependentType()) {
4630  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4631  Param, Template, Converted,
4632  SourceRange(TemplateLoc, RAngleLoc));
4633  if (Inst.isInvalid())
4634  return nullptr;
4635 
4636  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4637 
4638  // Only substitute for the innermost template argument list.
4639  MultiLevelTemplateArgumentList TemplateArgLists;
4640  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4641  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4642  TemplateArgLists.addOuterTemplateArguments(None);
4643 
4644  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4645  ArgType =
4646  SemaRef.SubstType(ArgType, TemplateArgLists,
4647  Param->getDefaultArgumentLoc(), Param->getDeclName());
4648  }
4649 
4650  return ArgType;
4651 }
4652 
4653 /// Substitute template arguments into the default template argument for
4654 /// the given non-type template parameter.
4655 ///
4656 /// \param SemaRef the semantic analysis object for which we are performing
4657 /// the substitution.
4658 ///
4659 /// \param Template the template that we are synthesizing template arguments
4660 /// for.
4661 ///
4662 /// \param TemplateLoc the location of the template name that started the
4663 /// template-id we are checking.
4664 ///
4665 /// \param RAngleLoc the location of the right angle bracket ('>') that
4666 /// terminates the template-id.
4667 ///
4668 /// \param Param the non-type template parameter whose default we are
4669 /// substituting into.
4670 ///
4671 /// \param Converted the list of template arguments provided for template
4672 /// parameters that precede \p Param in the template parameter list.
4673 ///
4674 /// \returns the substituted template argument, or NULL if an error occurred.
4675 static ExprResult
4677  TemplateDecl *Template,
4678  SourceLocation TemplateLoc,
4679  SourceLocation RAngleLoc,
4680  NonTypeTemplateParmDecl *Param,
4681  SmallVectorImpl<TemplateArgument> &Converted) {
4682  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4683  Param, Template, Converted,
4684  SourceRange(TemplateLoc, RAngleLoc));
4685  if (Inst.isInvalid())
4686  return ExprError();
4687 
4688  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4689 
4690  // Only substitute for the innermost template argument list.
4691  MultiLevelTemplateArgumentList TemplateArgLists;
4692  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4693  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4694  TemplateArgLists.addOuterTemplateArguments(None);
4695 
4696  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4697  EnterExpressionEvaluationContext ConstantEvaluated(
4699  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
4700 }
4701 
4702 /// Substitute template arguments into the default template argument for
4703 /// the given template template parameter.
4704 ///
4705 /// \param SemaRef the semantic analysis object for which we are performing
4706 /// the substitution.
4707 ///
4708 /// \param Template the template that we are synthesizing template arguments
4709 /// for.
4710 ///
4711 /// \param TemplateLoc the location of the template name that started the
4712 /// template-id we are checking.
4713 ///
4714 /// \param RAngleLoc the location of the right angle bracket ('>') that
4715 /// terminates the template-id.
4716 ///
4717 /// \param Param the template template parameter whose default we are
4718 /// substituting into.
4719 ///
4720 /// \param Converted the list of template arguments provided for template
4721 /// parameters that precede \p Param in the template parameter list.
4722 ///
4723 /// \param QualifierLoc Will be set to the nested-name-specifier (with
4724 /// source-location information) that precedes the template name.
4725 ///
4726 /// \returns the substituted template argument, or NULL if an error occurred.
4727 static TemplateName
4729  TemplateDecl *Template,
4730  SourceLocation TemplateLoc,
4731  SourceLocation RAngleLoc,
4732  TemplateTemplateParmDecl *Param,
4734  NestedNameSpecifierLoc &QualifierLoc) {
4736  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
4737  SourceRange(TemplateLoc, RAngleLoc));
4738  if (Inst.isInvalid())
4739  return TemplateName();
4740 
4741  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4742 
4743  // Only substitute for the innermost template argument list.
4744  MultiLevelTemplateArgumentList TemplateArgLists;
4745  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4746  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4747  TemplateArgLists.addOuterTemplateArguments(None);
4748 
4749  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4750  // Substitute into the nested-name-specifier first,
4751  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
4752  if (QualifierLoc) {
4753  QualifierLoc =
4754  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
4755  if (!QualifierLoc)
4756  return TemplateName();
4757  }
4758 
4759  return SemaRef.SubstTemplateName(
4760  QualifierLoc,
4763  TemplateArgLists);
4764 }
4765 
4766 /// If the given template parameter has a default template
4767 /// argument, substitute into that default template argument and
4768 /// return the corresponding template argument.
4771  SourceLocation TemplateLoc,
4772  SourceLocation RAngleLoc,
4773  Decl *Param,
4775  &Converted,
4776  bool &HasDefaultArg) {
4777  HasDefaultArg = false;
4778 
4779  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
4780  if (!hasVisibleDefaultArgument(TypeParm))
4781  return TemplateArgumentLoc();
4782 
4783  HasDefaultArg = true;
4784  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
4785  TemplateLoc,
4786  RAngleLoc,
4787  TypeParm,
4788  Converted);
4789  if (DI)
4790  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
4791 
4792  return TemplateArgumentLoc();
4793  }
4794 
4795  if (NonTypeTemplateParmDecl *NonTypeParm
4796  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4797  if (!hasVisibleDefaultArgument(NonTypeParm))
4798  return TemplateArgumentLoc();
4799 
4800  HasDefaultArg = true;
4801  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
4802  TemplateLoc,
4803  RAngleLoc,
4804  NonTypeParm,
4805  Converted);
4806  if (Arg.isInvalid())
4807  return TemplateArgumentLoc();
4808 
4809  Expr *ArgE = Arg.getAs<Expr>();
4810  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
4811  }
4812 
4813  TemplateTemplateParmDecl *TempTempParm
4814  = cast<TemplateTemplateParmDecl>(Param);
4815  if (!hasVisibleDefaultArgument(TempTempParm))
4816  return TemplateArgumentLoc();
4817 
4818  HasDefaultArg = true;
4819  NestedNameSpecifierLoc QualifierLoc;
4820  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
4821  TemplateLoc,
4822  RAngleLoc,
4823  TempTempParm,
4824  Converted,
4825  QualifierLoc);
4826  if (TName.isNull())
4827  return TemplateArgumentLoc();
4828 
4829  return TemplateArgumentLoc(TemplateArgument(TName),
4830  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
4831  TempTempParm->getDefaultArgument().getTemplateNameLoc());
4832 }
4833 
4834 /// Convert a template-argument that we parsed as a type into a template, if
4835 /// possible. C++ permits injected-class-names to perform dual service as
4836 /// template template arguments and as template type arguments.
4838  // Extract and step over any surrounding nested-name-specifier.
4839  NestedNameSpecifierLoc QualLoc;
4840  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
4841  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
4842  return TemplateArgumentLoc();
4843 
4844  QualLoc = ETLoc.getQualifierLoc();
4845  TLoc = ETLoc.getNamedTypeLoc();
4846  }
4847 
4848  // If this type was written as an injected-class-name, it can be used as a
4849  // template template argument.
4850  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
4851  return TemplateArgumentLoc(InjLoc.getTypePtr()->getTemplateName(),
4852  QualLoc, InjLoc.getNameLoc());
4853 
4854  // If this type was written as an injected-class-name, it may have been
4855  // converted to a RecordType during instantiation. If the RecordType is
4856  // *not* wrapped in a TemplateSpecializationType and denotes a class
4857  // template specialization, it must have come from an injected-class-name.
4858  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
4859  if (auto *CTSD =
4860  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
4861  return TemplateArgumentLoc(TemplateName(CTSD->getSpecializedTemplate()),
4862  QualLoc, RecLoc.getNameLoc());
4863 
4864  return TemplateArgumentLoc();
4865 }
4866 
4867 /// Check that the given template argument corresponds to the given
4868 /// template parameter.
4869 ///
4870 /// \param Param The template parameter against which the argument will be
4871 /// checked.
4872 ///
4873 /// \param Arg The template argument, which may be updated due to conversions.
4874 ///
4875 /// \param Template The template in which the template argument resides.
4876 ///
4877 /// \param TemplateLoc The location of the template name for the template
4878 /// whose argument list we're matching.
4879 ///
4880 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
4881 /// the template argument list.
4882 ///
4883 /// \param ArgumentPackIndex The index into the argument pack where this
4884 /// argument will be placed. Only valid if the parameter is a parameter pack.
4885 ///
4886 /// \param Converted The checked, converted argument will be added to the
4887 /// end of this small vector.
4888 ///
4889 /// \param CTAK Describes how we arrived at this particular template argument:
4890 /// explicitly written, deduced, etc.
4891 ///
4892 /// \returns true on error, false otherwise.
4894  TemplateArgumentLoc &Arg,
4895  NamedDecl *Template,
4896  SourceLocation TemplateLoc,
4897  SourceLocation RAngleLoc,
4898  unsigned ArgumentPackIndex,
4901  // Check template type parameters.
4902  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
4903  return CheckTemplateTypeArgument(TTP, Arg, Converted);
4904 
4905  // Check non-type template parameters.
4906  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4907  // Do substitution on the type of the non-type template parameter
4908  // with the template arguments we've seen thus far. But if the
4909  // template has a dependent context then we cannot substitute yet.
4910  QualType NTTPType = NTTP->getType();
4911  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
4912  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
4913 
4914  if (NTTPType->isInstantiationDependentType() &&
4915  !isa<TemplateTemplateParmDecl>(Template) &&
4916  !Template->getDeclContext()->isDependentContext()) {
4917  // Do substitution on the type of the non-type template parameter.
4918  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4919  NTTP, Converted,
4920  SourceRange(TemplateLoc, RAngleLoc));
4921  if (Inst.isInvalid())
4922  return true;
4923 
4925  Converted);
4926 
4927  // If the parameter is a pack expansion, expand this slice of the pack.
4928  if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
4929  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
4930  ArgumentPackIndex);
4931  NTTPType = SubstType(PET->getPattern(),
4932  MultiLevelTemplateArgumentList(TemplateArgs),
4933  NTTP->getLocation(),
4934  NTTP->getDeclName());
4935  } else {
4936  NTTPType = SubstType(NTTPType,
4937  MultiLevelTemplateArgumentList(TemplateArgs),
4938  NTTP->getLocation(),
4939  NTTP->getDeclName());
4940  }
4941 
4942  // If that worked, check the non-type template parameter type
4943  // for validity.
4944  if (!NTTPType.isNull())
4945  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
4946  NTTP->getLocation());
4947  if (NTTPType.isNull())
4948  return true;
4949  }
4950 
4951  switch (Arg.getArgument().getKind()) {
4953  llvm_unreachable("Should never see a NULL template argument here");
4954 
4956  TemplateArgument Result;
4957  unsigned CurSFINAEErrors = NumSFINAEErrors;
4958  ExprResult Res =
4959  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
4960  Result, CTAK);
4961  if (Res.isInvalid())
4962  return true;
4963  // If the current template argument causes an error, give up now.
4964  if (CurSFINAEErrors < NumSFINAEErrors)
4965  return true;
4966 
4967  // If the resulting expression is new, then use it in place of the
4968  // old expression in the template argument.
4969  if (Res.get() != Arg.getArgument().getAsExpr()) {
4970  TemplateArgument TA(Res.get());
4971  Arg = TemplateArgumentLoc(TA, Res.get());
4972  }
4973 
4974  Converted.push_back(Result);
4975  break;
4976  }
4977 
4981  // We've already checked this template argument, so just copy
4982  // it to the list of converted arguments.
4983  Converted.push_back(Arg.getArgument());
4984  break;
4985 
4988  // We were given a template template argument. It may not be ill-formed;
4989  // see below.
4990  if (DependentTemplateName *DTN
4993  // We have a template argument such as \c T::template X, which we
4994  // parsed as a template template argument. However, since we now
4995  // know that we need a non-type template argument, convert this
4996  // template name into an expression.
4997 
4998  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
4999  Arg.getTemplateNameLoc());
5000 
5001  CXXScopeSpec SS;
5002  SS.Adopt(Arg.getTemplateQualifierLoc());
5003  // FIXME: the template-template arg was a DependentTemplateName,
5004  // so it was provided with a template keyword. However, its source
5005  // location is not stored in the template argument structure.
5006  SourceLocation TemplateKWLoc;
5008  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
5009  nullptr);
5010 
5011  // If we parsed the template argument as a pack expansion, create a
5012  // pack expansion expression.
5014  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
5015  if (E.isInvalid())
5016  return true;
5017  }
5018 
5019  TemplateArgument Result;
5020  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
5021  if (E.isInvalid())
5022  return true;
5023 
5024  Converted.push_back(Result);
5025  break;
5026  }
5027 
5028  // We have a template argument that actually does refer to a class
5029  // template, alias template, or template template parameter, and
5030  // therefore cannot be a non-type template argument.
5031  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
5032  << Arg.getSourceRange();
5033 
5034  Diag(Param->getLocation(), diag::note_template_param_here);
5035  return true;
5036 
5037  case TemplateArgument::Type: {
5038  // We have a non-type template parameter but the template
5039  // argument is a type.
5040 
5041  // C++ [temp.arg]p2:
5042  // In a template-argument, an ambiguity between a type-id and
5043  // an expression is resolved to a type-id, regardless of the
5044  // form of the corresponding template-parameter.
5045  //
5046  // We warn specifically about this case, since it can be rather
5047  // confusing for users.
5048  QualType T = Arg.getArgument().getAsType();
5049  SourceRange SR = Arg.getSourceRange();
5050  if (T->isFunctionType())
5051  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
5052  else
5053  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
5054  Diag(Param->getLocation(), diag::note_template_param_here);
5055  return true;
5056  }
5057 
5059  llvm_unreachable("Caller must expand template argument packs");
5060  }
5061 
5062  return false;
5063  }
5064 
5065 
5066  // Check template template parameters.
5067  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
5068 
5069  TemplateParameterList *Params = TempParm->getTemplateParameters();
5070  if (TempParm->isExpandedParameterPack())
5071  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
5072 
5073  // Substitute into the template parameter list of the template
5074  // template parameter, since previously-supplied template arguments
5075  // may appear within the template template parameter.
5076  //
5077  // FIXME: Skip this if the parameters aren't instantiation-dependent.
5078  {
5079  // Set up a template instantiation context.
5081  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5082  TempParm, Converted,
5083  SourceRange(TemplateLoc, RAngleLoc));
5084  if (Inst.isInvalid())
5085  return true;
5086 
5087  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5088  Params = SubstTemplateParams(Params, CurContext,
5089  MultiLevelTemplateArgumentList(TemplateArgs));
5090  if (!Params)
5091  return true;
5092  }
5093 
5094  // C++1z [temp.local]p1: (DR1004)
5095  // When [the injected-class-name] is used [...] as a template-argument for
5096  // a template template-parameter [...] it refers to the class template
5097  // itself.
5098  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
5100  Arg.getTypeSourceInfo()->getTypeLoc());
5101  if (!ConvertedArg.getArgument().isNull())
5102  Arg = ConvertedArg;
5103  }
5104 
5105  switch (Arg.getArgument().getKind()) {
5107  llvm_unreachable("Should never see a NULL template argument here");
5108 
5111  if (CheckTemplateTemplateArgument(Params, Arg))
5112  return true;
5113 
5114  Converted.push_back(Arg.getArgument());
5115  break;
5116 
5119  // We have a template template parameter but the template
5120  // argument does not refer to a template.
5121  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
5122  << getLangOpts().CPlusPlus11;
5123  return true;
5124 
5126  llvm_unreachable("Declaration argument with template template parameter");
5128  llvm_unreachable("Integral argument with template template parameter");
5130  llvm_unreachable("Null pointer argument with template template parameter");
5131 
5133  llvm_unreachable("Caller must expand template argument packs");
5134  }
5135 
5136  return false;
5137 }
5138 
5139 /// Check whether the template parameter is a pack expansion, and if so,
5140 /// determine the number of parameters produced by that expansion. For instance:
5141 ///
5142 /// \code
5143 /// template<typename ...Ts> struct A {
5144 /// template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
5145 /// };
5146 /// \endcode
5147 ///
5148 /// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
5149 /// is not a pack expansion, so returns an empty Optional.
5151  if (NonTypeTemplateParmDecl *NTTP
5152  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5153  if (NTTP->isExpandedParameterPack())
5154  return NTTP->getNumExpansionTypes();
5155  }
5156 
5157  if (TemplateTemplateParmDecl *TTP
5158  = dyn_cast<TemplateTemplateParmDecl>(Param)) {
5159  if (TTP->isExpandedParameterPack())
5160  return TTP->getNumExpansionTemplateParameters();
5161  }
5162 
5163  return None;
5164 }
5165 
5166 /// Diagnose a missing template argument.
5167 template<typename TemplateParmDecl>
5169  TemplateDecl *TD,
5170  const TemplateParmDecl *D,
5171  TemplateArgumentListInfo &Args) {
5172  // Dig out the most recent declaration of the template parameter; there may be
5173  // declarations of the template that are more recent than TD.
5174  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
5175  ->getTemplateParameters()
5176  ->getParam(D->getIndex()));
5177 
5178  // If there's a default argument that's not visible, diagnose that we're
5179  // missing a module import.
5181  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5182  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5183  D->getDefaultArgumentLoc(), Modules,
5185  /*Recover*/true);
5186  return true;
5187  }
5188 
5189  // FIXME: If there's a more recent default argument that *is* visible,
5190  // diagnose that it was declared too late.
5191 
5193 
5194  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5195  << /*not enough args*/0
5197  << TD;
5198  S.Diag(TD->getLocation(), diag::note_template_decl_here)
5199  << Params->getSourceRange();
5200  return true;
5201 }
5202 
5203 /// Check that the given template argument list is well-formed
5204 /// for specializing the given template.
5206  TemplateDecl *Template, SourceLocation TemplateLoc,
5207  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
5209  bool UpdateArgsWithConversions) {
5210  // Make a copy of the template arguments for processing. Only make the
5211  // changes at the end when successful in matching the arguments to the
5212  // template.
5213  TemplateArgumentListInfo NewArgs = TemplateArgs;
5214 
5215  // Make sure we get the template parameter list from the most
5216  // recentdeclaration, since that is the only one that has is guaranteed to
5217  // have all the default template argument information.
5218  TemplateParameterList *Params =
5219  cast<TemplateDecl>(Template->getMostRecentDecl())
5220  ->getTemplateParameters();
5221 
5222  SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
5223 
5224  // C++ [temp.arg]p1:
5225  // [...] The type and form of each template-argument specified in
5226  // a template-id shall match the type and form specified for the
5227  // corresponding parameter declared by the template in its
5228  // template-parameter-list.
5229  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
5230  SmallVector<TemplateArgument, 2> ArgumentPack;
5231  unsigned ArgIdx = 0, NumArgs = NewArgs.size();
5232  LocalInstantiationScope InstScope(*this, true);
5233  for (TemplateParameterList::iterator Param = Params->begin(),
5234  ParamEnd = Params->end();
5235  Param != ParamEnd; /* increment in loop */) {
5236  // If we have an expanded parameter pack, make sure we don't have too
5237  // many arguments.
5238  if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
5239  if (*Expansions == ArgumentPack.size()) {
5240  // We're done with this parameter pack. Pack up its arguments and add
5241  // them to the list.
5242  Converted.push_back(
5243  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5244  ArgumentPack.clear();
5245 
5246  // This argument is assigned to the next parameter.
5247  ++Param;
5248  continue;
5249  } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
5250  // Not enough arguments for this parameter pack.
5251  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5252  << /*not enough args*/0
5253  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5254  << Template;
5255  Diag(Template->getLocation(), diag::note_template_decl_here)
5256  << Params->getSourceRange();
5257  return true;
5258  }
5259  }
5260 
5261  if (ArgIdx < NumArgs) {
5262  // Check the template argument we were given.
5263  if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
5264  TemplateLoc, RAngleLoc,
5265  ArgumentPack.size(), Converted))
5266  return true;
5267 
5268  bool PackExpansionIntoNonPack =
5269  NewArgs[ArgIdx].getArgument().isPackExpansion() &&
5270  (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
5271  if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
5272  // Core issue 1430: we have a pack expansion as an argument to an
5273  // alias template, and it's not part of a parameter pack. This
5274  // can't be canonicalized, so reject it now.
5275  Diag(NewArgs[ArgIdx].getLocation(),
5276  diag::err_alias_template_expansion_into_fixed_list)
5277  << NewArgs[ArgIdx].getSourceRange();
5278  Diag((*Param)->getLocation(), diag::note_template_param_here);
5279  return true;
5280  }
5281 
5282  // We're now done with this argument.
5283  ++ArgIdx;
5284 
5285  if ((*Param)->isTemplateParameterPack()) {
5286  // The template parameter was a template parameter pack, so take the
5287  // deduced argument and place it on the argument pack. Note that we
5288  // stay on the same template parameter so that we can deduce more
5289  // arguments.
5290  ArgumentPack.push_back(Converted.pop_back_val());
5291  } else {
5292  // Move to the next template parameter.
5293  ++Param;
5294  }
5295 
5296  // If we just saw a pack expansion into a non-pack, then directly convert
5297  // the remaining arguments, because we don't know what parameters they'll
5298  // match up with.
5299  if (PackExpansionIntoNonPack) {
5300  if (!ArgumentPack.empty()) {
5301  // If we were part way through filling in an expanded parameter pack,
5302  // fall back to just producing individual arguments.
5303  Converted.insert(Converted.end(),
5304  ArgumentPack.begin(), ArgumentPack.end());
5305  ArgumentPack.clear();
5306  }
5307 
5308  while (ArgIdx < NumArgs) {
5309  Converted.push_back(NewArgs[ArgIdx].getArgument());
5310  ++ArgIdx;
5311  }
5312 
5313  return false;
5314  }
5315 
5316  continue;
5317  }
5318 
5319  // If we're checking a partial template argument list, we're done.
5320  if (PartialTemplateArgs) {
5321  if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
5322  Converted.push_back(
5323  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5324 
5325  return false;
5326  }
5327 
5328  // If we have a template parameter pack with no more corresponding
5329  // arguments, just break out now and we'll fill in the argument pack below.
5330  if ((*Param)->isTemplateParameterPack()) {
5331  assert(!getExpandedPackSize(*Param) &&
5332  "Should have dealt with this already");
5333 
5334  // A non-expanded parameter pack before the end of the parameter list
5335  // only occurs for an ill-formed template parameter list, unless we've
5336  // got a partial argument list for a function template, so just bail out.
5337  if (Param + 1 != ParamEnd)
5338  return true;
5339 
5340  Converted.push_back(
5341  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5342  ArgumentPack.clear();
5343 
5344  ++Param;
5345  continue;
5346  }
5347 
5348  // Check whether we have a default argument.
5349  TemplateArgumentLoc Arg;
5350 
5351  // Retrieve the default template argument from the template
5352  // parameter. For each kind of template parameter, we substitute the
5353  // template arguments provided thus far and any "outer" template arguments
5354  // (when the template parameter was part of a nested template) into
5355  // the default argument.
5356  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
5357  if (!hasVisibleDefaultArgument(TTP))
5358  return diagnoseMissingArgument(*this, TemplateLoc, Template, TTP,
5359  NewArgs);
5360 
5362  Template,
5363  TemplateLoc,
5364  RAngleLoc,
5365  TTP,
5366  Converted);
5367  if (!ArgType)
5368  return true;
5369 
5370  Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
5371  ArgType);
5372  } else if (NonTypeTemplateParmDecl *NTTP
5373  = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
5374  if (!hasVisibleDefaultArgument(NTTP))
5375  return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
5376  NewArgs);
5377 
5378  ExprResult E = SubstDefaultTemplateArgument(*this, Template,
5379  TemplateLoc,
5380  RAngleLoc,
5381  NTTP,
5382  Converted);
5383  if (E.isInvalid())
5384  return true;
5385 
5386  Expr *Ex = E.getAs<Expr>();
5387  Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
5388  } else {
5389  TemplateTemplateParmDecl *TempParm
5390  = cast<TemplateTemplateParmDecl>(*Param);
5391 
5392  if (!hasVisibleDefaultArgument(TempParm))
5393  return diagnoseMissingArgument(*this, TemplateLoc, Template, TempParm,
5394  NewArgs);
5395 
5396  NestedNameSpecifierLoc QualifierLoc;
5397  TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
5398  TemplateLoc,
5399  RAngleLoc,
5400  TempParm,
5401  Converted,
5402  QualifierLoc);
5403  if (Name.isNull())
5404  return true;
5405 
5406  Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
5407  TempParm->getDefaultArgument().getTemplateNameLoc());
5408  }
5409 
5410  // Introduce an instantiation record that describes where we are using
5411  // the default template argument. We're not actually instantiating a
5412  // template here, we just create this object to put a note into the
5413  // context stack.
5414  InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
5415  SourceRange(TemplateLoc, RAngleLoc));
5416  if (Inst.isInvalid())
5417  return true;
5418 
5419  // Check the default template argument.
5420  if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
5421  RAngleLoc, 0, Converted))
5422  return true;
5423 
5424  // Core issue 150 (assumed resolution): if this is a template template
5425  // parameter, keep track of the default template arguments from the
5426  // template definition.
5427  if (isTemplateTemplateParameter)
5428  NewArgs.addArgument(Arg);
5429 
5430  // Move to the next template parameter and argument.
5431  ++Param;
5432  ++ArgIdx;
5433  }
5434 
5435  // If we're performing a partial argument substitution, allow any trailing
5436  // pack expansions; they might be empty. This can happen even if
5437  // PartialTemplateArgs is false (the list of arguments is complete but
5438  // still dependent).
5439  if (ArgIdx < NumArgs && CurrentInstantiationScope &&
5440  CurrentInstantiationScope->getPartiallySubstitutedPack()) {
5441  while (ArgIdx < NumArgs && NewArgs[ArgIdx].getArgument().isPackExpansion())
5442  Converted.push_back(NewArgs[ArgIdx++].getArgument());
5443  }
5444 
5445  // If we have any leftover arguments, then there were too many arguments.
5446  // Complain and fail.
5447  if (ArgIdx < NumArgs) {
5448  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5449  << /*too many args*/1
5450  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5451  << Template
5452  << SourceRange(NewArgs[ArgIdx].getLocation(), NewArgs.getRAngleLoc());
5453  Diag(Template->getLocation(), diag::note_template_decl_here)
5454  << Params->getSourceRange();
5455  return true;
5456  }
5457 
5458  // No problems found with the new argument list, propagate changes back
5459  // to caller.
5460  if (UpdateArgsWithConversions)
5461  TemplateArgs = std::move(NewArgs);
5462 
5463  return false;
5464 }
5465 
5466 namespace {
5467  class UnnamedLocalNoLinkageFinder
5468  : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
5469  {
5470  Sema &S;
5471  SourceRange SR;
5472 
5474 
5475  public:
5476  UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
5477 
5478  bool Visit(QualType T) {
5479  return T.isNull() ? false : inherited::Visit(T.getTypePtr());
5480  }
5481 
5482 #define TYPE(Class, Parent) \
5483  bool Visit##Class##Type(const Class##Type *);
5484 #define ABSTRACT_TYPE(Class, Parent) \
5485  bool Visit##Class##Type(const Class##Type *) { return false; }
5486 #define NON_CANONICAL_TYPE(Class, Parent) \
5487  bool Visit##Class##Type(const Class##Type *) { return false; }
5488 #include "clang/AST/TypeNodes.inc"
5489 
5490  bool VisitTagDecl(const TagDecl *Tag);
5491  bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
5492  };
5493 } // end anonymous namespace
5494 
5495 bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
5496  return false;
5497 }
5498 
5499 bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
5500  return Visit(T->getElementType());
5501 }
5502 
5503 bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
5504  return Visit(T->getPointeeType());
5505 }
5506 
5507 bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
5508  const BlockPointerType* T) {
5509  return Visit(T->getPointeeType());
5510 }
5511 
5512 bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
5513  const LValueReferenceType* T) {
5514  return Visit(T->getPointeeType());
5515 }
5516 
5517 bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
5518  const RValueReferenceType* T) {
5519  return Visit(T->getPointeeType());
5520 }
5521 
5522 bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
5523  const MemberPointerType* T) {
5524  return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
5525 }
5526 
5527 bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
5528  const ConstantArrayType* T) {
5529  return Visit(T->getElementType());
5530 }
5531 
5532 bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
5533  const IncompleteArrayType* T) {
5534  return Visit(T->getElementType());
5535 }
5536 
5537 bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
5538  const VariableArrayType* T) {
5539  return Visit(T->getElementType());
5540 }
5541 
5542 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
5543  const DependentSizedArrayType* T) {
5544  return Visit(T->getElementType());
5545 }
5546 
5547 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
5548  const DependentSizedExtVectorType* T) {
5549  return Visit(T->getElementType());
5550 }
5551 
5552 bool UnnamedLocalNoLinkageFinder::VisitDependentAddressSpaceType(
5553  const DependentAddressSpaceType *T) {
5554  return Visit(T->getPointeeType());
5555 }
5556 
5557 bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
5558  return Visit(T->getElementType());
5559 }
5560 
5561 bool UnnamedLocalNoLinkageFinder::VisitDependentVectorType(
5562  const DependentVectorType *T) {
5563  return Visit(T->getElementType());
5564 }
5565 
5566 bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
5567  return Visit(T->getElementType());
5568 }
5569 
5570 bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
5571  const FunctionProtoType* T) {
5572  for (const auto &A : T->param_types()) {
5573  if (Visit(A))
5574  return true;
5575  }
5576 
5577  return Visit(T->getReturnType());
5578 }
5579 
5580 bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
5581  const FunctionNoProtoType* T) {
5582  return Visit(T->getReturnType());
5583 }
5584 
5585 bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
5586  const UnresolvedUsingType*) {
5587  return false;
5588 }
5589 
5590 bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
5591  return false;
5592 }
5593 
5594 bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
5595  return Visit(T->getUnderlyingType());
5596 }
5597 
5598 bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
5599  return false;
5600 }
5601 
5602 bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
5603  const UnaryTransformType*) {
5604  return false;
5605 }
5606 
5607 bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
5608  return Visit(T->getDeducedType());
5609 }
5610 
5611 bool UnnamedLocalNoLinkageFinder::VisitDeducedTemplateSpecializationType(
5613  return Visit(T->getDeducedType());
5614 }
5615 
5616 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
5617  return VisitTagDecl(T->getDecl());
5618 }
5619 
5620 bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
5621  return VisitTagDecl(T->getDecl());
5622 }
5623 
5624 bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
5625  const TemplateTypeParmType*) {
5626  return false;
5627 }
5628 
5629 bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
5631  return false;
5632 }
5633 
5634 bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
5635  const TemplateSpecializationType*) {
5636  return false;
5637 }
5638 
5639 bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
5640  const InjectedClassNameType* T) {
5641  return VisitTagDecl(T->getDecl());
5642 }
5643 
5644 bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
5645  const DependentNameType* T) {
5646  return VisitNestedNameSpecifier(T->getQualifier());
5647 }
5648 
5649 bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
5651  return VisitNestedNameSpecifier(T->getQualifier());
5652 }
5653 
5654 bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
5655  const PackExpansionType* T) {
5656  return Visit(T->getPattern());
5657 }
5658 
5659 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
5660  return false;
5661 }
5662 
5663 bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
5664  const ObjCInterfaceType *) {
5665  return false;
5666 }
5667 
5668 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
5669  const ObjCObjectPointerType *) {
5670  return false;
5671 }
5672 
5673 bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
5674  return Visit(T->getValueType());
5675 }
5676 
5677 bool UnnamedLocalNoLinkageFinder::VisitPipeType(const PipeType* T) {
5678  return false;
5679 }
5680 
5681 bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
5682  if (Tag->getDeclContext()->isFunctionOrMethod()) {
5683  S.Diag(SR.getBegin(),
5684  S.getLangOpts().CPlusPlus11 ?
5685  diag::warn_cxx98_compat_template_arg_local_type :
5686  diag::ext_template_arg_local_type)
5687  << S.Context.getTypeDeclType(Tag) << SR;
5688  return true;
5689  }
5690 
5691  if (!Tag->hasNameForLinkage()) {
5692  S.Diag(SR.getBegin(),
5693  S.getLangOpts().CPlusPlus11 ?
5694  diag::warn_cxx98_compat_template_arg_unnamed_type :
5695  diag::ext_template_arg_unnamed_type) << SR;
5696  S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
5697  return true;
5698  }
5699 
5700  return false;
5701 }
5702 
5703 bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
5704  NestedNameSpecifier *NNS) {
5705  if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
5706  return true;
5707 
5708  switch (NNS->getKind()) {
5714  return false;
5715 
5718  return Visit(QualType(NNS->getAsType(), 0));
5719  }
5720  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
5721 }
5722 
5723 /// Check a template argument against its corresponding
5724 /// template type parameter.
5725 ///
5726 /// This routine implements the semantics of C++ [temp.arg.type]. It
5727 /// returns true if an error occurred, and false otherwise.
5729  TypeSourceInfo *ArgInfo) {
5730  assert(ArgInfo && "invalid TypeSourceInfo");
5731  QualType Arg = ArgInfo->getType();
5732  SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
5733 
5734  if (Arg->isVariablyModifiedType()) {
5735  return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
5736  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
5737  return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
5738  }
5739 
5740  // C++03 [temp.arg.type]p2:
5741  // A local type, a type with no linkage, an unnamed type or a type
5742  // compounded from any of these types shall not be used as a
5743  // template-argument for a template type-parameter.
5744  //
5745  // C++11 allows these, and even in C++03 we allow them as an extension with
5746  // a warning.
5747  if (LangOpts.CPlusPlus11 || Arg->hasUnnamedOrLocalType()) {
5748  UnnamedLocalNoLinkageFinder Finder(*this, SR);
5749  (void)Finder.Visit(Context.getCanonicalType(Arg));
5750  }
5751 
5752  return false;
5753 }
5754 
5759 };
5760 
5761 /// Determine whether the given template argument is a null pointer
5762 /// value of the appropriate type.
5763 static NullPointerValueKind
5765  QualType ParamType, Expr *Arg,
5766  Decl *Entity = nullptr) {
5767  if (Arg->isValueDependent() || Arg->isTypeDependent())
5768  return NPV_NotNullPointer;
5769 
5770  // dllimport'd entities aren't constant but are available inside of template
5771  // arguments.
5772  if (Entity && Entity->hasAttr<DLLImportAttr>())
5773  return NPV_NotNullPointer;
5774 
5775  if (!S.isCompleteType(Arg->getExprLoc(), ParamType))
5776  llvm_unreachable(
5777  "Incomplete parameter type in isNullPointerValueTemplateArgument!");
5778 
5779  if (!S.getLangOpts().CPlusPlus11)
5780  return NPV_NotNullPointer;
5781 
5782  // Determine whether we have a constant expression.
5783