clang  8.0.0svn
SemaTemplate.cpp
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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements semantic analysis for C++ templates.
10 //===----------------------------------------------------------------------===//
11 
12 #include "TreeTransform.h"
13 #include "clang/AST/ASTConsumer.h"
14 #include "clang/AST/ASTContext.h"
15 #include "clang/AST/DeclFriend.h"
16 #include "clang/AST/DeclTemplate.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/TypeVisitor.h"
21 #include "clang/Basic/Builtins.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
26 #include "clang/Sema/Lookup.h"
28 #include "clang/Sema/Scope.h"
30 #include "clang/Sema/Template.h"
32 #include "llvm/ADT/SmallBitVector.h"
33 #include "llvm/ADT/SmallString.h"
34 #include "llvm/ADT/StringExtras.h"
35 
36 #include <iterator>
37 using namespace clang;
38 using namespace sema;
39 
40 // Exported for use by Parser.
43  unsigned N) {
44  if (!N) return SourceRange();
45  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
46 }
47 
48 namespace clang {
49 /// [temp.constr.decl]p2: A template's associated constraints are
50 /// defined as a single constraint-expression derived from the introduced
51 /// constraint-expressions [ ... ].
52 ///
53 /// \param Params The template parameter list and optional requires-clause.
54 ///
55 /// \param FD The underlying templated function declaration for a function
56 /// template.
58  FunctionDecl *FD);
59 }
60 
62  FunctionDecl *FD) {
63  // FIXME: Concepts: collect additional introduced constraint-expressions
64  assert(!FD && "Cannot collect constraints from function declaration yet.");
65  return Params->getRequiresClause();
66 }
67 
68 /// Determine whether the declaration found is acceptable as the name
69 /// of a template and, if so, return that template declaration. Otherwise,
70 /// returns NULL.
72  NamedDecl *Orig,
73  bool AllowFunctionTemplates) {
74  NamedDecl *D = Orig->getUnderlyingDecl();
75 
76  if (isa<TemplateDecl>(D)) {
77  if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
78  return nullptr;
79 
80  return Orig;
81  }
82 
83  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
84  // C++ [temp.local]p1:
85  // Like normal (non-template) classes, class templates have an
86  // injected-class-name (Clause 9). The injected-class-name
87  // can be used with or without a template-argument-list. When
88  // it is used without a template-argument-list, it is
89  // equivalent to the injected-class-name followed by the
90  // template-parameters of the class template enclosed in
91  // <>. When it is used with a template-argument-list, it
92  // refers to the specified class template specialization,
93  // which could be the current specialization or another
94  // specialization.
95  if (Record->isInjectedClassName()) {
96  Record = cast<CXXRecordDecl>(Record->getDeclContext());
97  if (Record->getDescribedClassTemplate())
98  return Record->getDescribedClassTemplate();
99 
101  = dyn_cast<ClassTemplateSpecializationDecl>(Record))
102  return Spec->getSpecializedTemplate();
103  }
104 
105  return nullptr;
106  }
107 
108  // 'using Dependent::foo;' can resolve to a template name.
109  // 'using typename Dependent::foo;' cannot (not even if 'foo' is an
110  // injected-class-name).
111  if (isa<UnresolvedUsingValueDecl>(D))
112  return D;
113 
114  return nullptr;
115 }
116 
118  bool AllowFunctionTemplates) {
119  // The set of class templates we've already seen.
120  llvm::SmallPtrSet<ClassTemplateDecl *, 8> ClassTemplates;
121  LookupResult::Filter filter = R.makeFilter();
122  while (filter.hasNext()) {
123  NamedDecl *Orig = filter.next();
124  NamedDecl *Repl = isAcceptableTemplateName(Context, Orig,
125  AllowFunctionTemplates);
126  if (!Repl)
127  filter.erase();
128  else if (Repl != Orig) {
129 
130  // C++ [temp.local]p3:
131  // A lookup that finds an injected-class-name (10.2) can result in an
132  // ambiguity in certain cases (for example, if it is found in more than
133  // one base class). If all of the injected-class-names that are found
134  // refer to specializations of the same class template, and if the name
135  // is used as a template-name, the reference refers to the class
136  // template itself and not a specialization thereof, and is not
137  // ambiguous.
138  if (ClassTemplateDecl *ClassTmpl = dyn_cast<ClassTemplateDecl>(Repl))
139  if (!ClassTemplates.insert(ClassTmpl).second) {
140  filter.erase();
141  continue;
142  }
143 
144  // FIXME: we promote access to public here as a workaround to
145  // the fact that LookupResult doesn't let us remember that we
146  // found this template through a particular injected class name,
147  // which means we end up doing nasty things to the invariants.
148  // Pretending that access is public is *much* safer.
149  filter.replace(Repl, AS_public);
150  }
151  }
152  filter.done();
153 }
154 
156  bool AllowFunctionTemplates) {
157  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I)
158  if (isAcceptableTemplateName(Context, *I, AllowFunctionTemplates))
159  return true;
160 
161  return false;
162 }
163 
165  CXXScopeSpec &SS,
166  bool hasTemplateKeyword,
167  const UnqualifiedId &Name,
168  ParsedType ObjectTypePtr,
169  bool EnteringContext,
170  TemplateTy &TemplateResult,
171  bool &MemberOfUnknownSpecialization) {
172  assert(getLangOpts().CPlusPlus && "No template names in C!");
173 
174  DeclarationName TName;
175  MemberOfUnknownSpecialization = false;
176 
177  switch (Name.getKind()) {
179  TName = DeclarationName(Name.Identifier);
180  break;
181 
183  TName = Context.DeclarationNames.getCXXOperatorName(
185  break;
186 
189  break;
190 
191  default:
192  return TNK_Non_template;
193  }
194 
195  QualType ObjectType = ObjectTypePtr.get();
196 
197  LookupResult R(*this, TName, Name.getBeginLoc(), LookupOrdinaryName);
198  if (LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
199  MemberOfUnknownSpecialization))
200  return TNK_Non_template;
201  if (R.empty()) return TNK_Non_template;
202  if (R.isAmbiguous()) {
203  // Suppress diagnostics; we'll redo this lookup later.
204  R.suppressDiagnostics();
205 
206  // FIXME: we might have ambiguous templates, in which case we
207  // should at least parse them properly!
208  return TNK_Non_template;
209  }
210 
211  TemplateName Template;
212  TemplateNameKind TemplateKind;
213 
214  unsigned ResultCount = R.end() - R.begin();
215  if (ResultCount > 1) {
216  // We assume that we'll preserve the qualifier from a function
217  // template name in other ways.
218  Template = Context.getOverloadedTemplateName(R.begin(), R.end());
219  TemplateKind = TNK_Function_template;
220 
221  // We'll do this lookup again later.
222  R.suppressDiagnostics();
223  } else if (isa<UnresolvedUsingValueDecl>((*R.begin())->getUnderlyingDecl())) {
224  // We don't yet know whether this is a template-name or not.
225  MemberOfUnknownSpecialization = true;
226  return TNK_Non_template;
227  } else {
228  TemplateDecl *TD = cast<TemplateDecl>((*R.begin())->getUnderlyingDecl());
229 
230  if (SS.isSet() && !SS.isInvalid()) {
231  NestedNameSpecifier *Qualifier = SS.getScopeRep();
232  Template = Context.getQualifiedTemplateName(Qualifier,
233  hasTemplateKeyword, TD);
234  } else {
235  Template = TemplateName(TD);
236  }
237 
238  if (isa<FunctionTemplateDecl>(TD)) {
239  TemplateKind = TNK_Function_template;
240 
241  // We'll do this lookup again later.
242  R.suppressDiagnostics();
243  } else {
244  assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
245  isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
246  isa<BuiltinTemplateDecl>(TD));
247  TemplateKind =
248  isa<VarTemplateDecl>(TD) ? TNK_Var_template : TNK_Type_template;
249  }
250  }
251 
252  TemplateResult = TemplateTy::make(Template);
253  return TemplateKind;
254 }
255 
257  SourceLocation NameLoc,
258  ParsedTemplateTy *Template) {
259  CXXScopeSpec SS;
260  bool MemberOfUnknownSpecialization = false;
261 
262  // We could use redeclaration lookup here, but we don't need to: the
263  // syntactic form of a deduction guide is enough to identify it even
264  // if we can't look up the template name at all.
265  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
266  if (LookupTemplateName(R, S, SS, /*ObjectType*/ QualType(),
267  /*EnteringContext*/ false,
268  MemberOfUnknownSpecialization))
269  return false;
270 
271  if (R.empty()) return false;
272  if (R.isAmbiguous()) {
273  // FIXME: Diagnose an ambiguity if we find at least one template.
275  return false;
276  }
277 
278  // We only treat template-names that name type templates as valid deduction
279  // guide names.
281  if (!TD || !getAsTypeTemplateDecl(TD))
282  return false;
283 
284  if (Template)
285  *Template = TemplateTy::make(TemplateName(TD));
286  return true;
287 }
288 
290  SourceLocation IILoc,
291  Scope *S,
292  const CXXScopeSpec *SS,
293  TemplateTy &SuggestedTemplate,
294  TemplateNameKind &SuggestedKind) {
295  // We can't recover unless there's a dependent scope specifier preceding the
296  // template name.
297  // FIXME: Typo correction?
298  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
299  computeDeclContext(*SS))
300  return false;
301 
302  // The code is missing a 'template' keyword prior to the dependent template
303  // name.
305  Diag(IILoc, diag::err_template_kw_missing)
306  << Qualifier << II.getName()
307  << FixItHint::CreateInsertion(IILoc, "template ");
308  SuggestedTemplate
309  = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
310  SuggestedKind = TNK_Dependent_template_name;
311  return true;
312 }
313 
315  Scope *S, CXXScopeSpec &SS,
316  QualType ObjectType,
317  bool EnteringContext,
318  bool &MemberOfUnknownSpecialization,
319  SourceLocation TemplateKWLoc) {
320  // Determine where to perform name lookup
321  MemberOfUnknownSpecialization = false;
322  DeclContext *LookupCtx = nullptr;
323  bool IsDependent = false;
324  if (!ObjectType.isNull()) {
325  // This nested-name-specifier occurs in a member access expression, e.g.,
326  // x->B::f, and we are looking into the type of the object.
327  assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
328  LookupCtx = computeDeclContext(ObjectType);
329  IsDependent = !LookupCtx;
330  assert((IsDependent || !ObjectType->isIncompleteType() ||
331  ObjectType->castAs<TagType>()->isBeingDefined()) &&
332  "Caller should have completed object type");
333 
334  // Template names cannot appear inside an Objective-C class or object type.
335  if (ObjectType->isObjCObjectOrInterfaceType()) {
336  Found.clear();
337  return false;
338  }
339  } else if (SS.isSet()) {
340  // This nested-name-specifier occurs after another nested-name-specifier,
341  // so long into the context associated with the prior nested-name-specifier.
342  LookupCtx = computeDeclContext(SS, EnteringContext);
343  IsDependent = !LookupCtx;
344 
345  // The declaration context must be complete.
346  if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
347  return true;
348  }
349 
350  bool ObjectTypeSearchedInScope = false;
351  bool AllowFunctionTemplatesInLookup = true;
352  if (LookupCtx) {
353  // Perform "qualified" name lookup into the declaration context we
354  // computed, which is either the type of the base of a member access
355  // expression or the declaration context associated with a prior
356  // nested-name-specifier.
357  LookupQualifiedName(Found, LookupCtx);
358 
359  // FIXME: The C++ standard does not clearly specify what happens in the
360  // case where the object type is dependent, and implementations vary. In
361  // Clang, we treat a name after a . or -> as a template-name if lookup
362  // finds a non-dependent member or member of the current instantiation that
363  // is a type template, or finds no such members and lookup in the context
364  // of the postfix-expression finds a type template. In the latter case, the
365  // name is nonetheless dependent, and we may resolve it to a member of an
366  // unknown specialization when we come to instantiate the template.
367  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
368  }
369 
370  if (!SS.isSet() && (ObjectType.isNull() || Found.empty())) {
371  // C++ [basic.lookup.classref]p1:
372  // In a class member access expression (5.2.5), if the . or -> token is
373  // immediately followed by an identifier followed by a <, the
374  // identifier must be looked up to determine whether the < is the
375  // beginning of a template argument list (14.2) or a less-than operator.
376  // The identifier is first looked up in the class of the object
377  // expression. If the identifier is not found, it is then looked up in
378  // the context of the entire postfix-expression and shall name a class
379  // template.
380  if (S)
381  LookupName(Found, S);
382 
383  if (!ObjectType.isNull()) {
384  // FIXME: We should filter out all non-type templates here, particularly
385  // variable templates and concepts. But the exclusion of alias templates
386  // and template template parameters is a wording defect.
387  AllowFunctionTemplatesInLookup = false;
388  ObjectTypeSearchedInScope = true;
389  }
390 
391  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
392  }
393 
394  if (Found.empty() && !IsDependent) {
395  // If we did not find any names, attempt to correct any typos.
396  DeclarationName Name = Found.getLookupName();
397  Found.clear();
398  // Simple filter callback that, for keywords, only accepts the C++ *_cast
399  auto FilterCCC = llvm::make_unique<CorrectionCandidateCallback>();
400  FilterCCC->WantTypeSpecifiers = false;
401  FilterCCC->WantExpressionKeywords = false;
402  FilterCCC->WantRemainingKeywords = false;
403  FilterCCC->WantCXXNamedCasts = true;
404  if (TypoCorrection Corrected = CorrectTypo(
405  Found.getLookupNameInfo(), Found.getLookupKind(), S, &SS,
406  std::move(FilterCCC), CTK_ErrorRecovery, LookupCtx)) {
407  Found.setLookupName(Corrected.getCorrection());
408  if (auto *ND = Corrected.getFoundDecl())
409  Found.addDecl(ND);
410  FilterAcceptableTemplateNames(Found);
411  if (!Found.empty()) {
412  if (LookupCtx) {
413  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
414  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
415  Name.getAsString() == CorrectedStr;
416  diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
417  << Name << LookupCtx << DroppedSpecifier
418  << SS.getRange());
419  } else {
420  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
421  }
422  }
423  } else {
424  Found.setLookupName(Name);
425  }
426  }
427 
428  NamedDecl *ExampleLookupResult =
429  Found.empty() ? nullptr : Found.getRepresentativeDecl();
430  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
431  if (Found.empty()) {
432  if (IsDependent) {
433  MemberOfUnknownSpecialization = true;
434  return false;
435  }
436 
437  // If a 'template' keyword was used, a lookup that finds only non-template
438  // names is an error.
439  if (ExampleLookupResult && TemplateKWLoc.isValid()) {
440  Diag(Found.getNameLoc(), diag::err_template_kw_refers_to_non_template)
441  << Found.getLookupName() << SS.getRange();
442  Diag(ExampleLookupResult->getUnderlyingDecl()->getLocation(),
443  diag::note_template_kw_refers_to_non_template)
444  << Found.getLookupName();
445  return true;
446  }
447 
448  return false;
449  }
450 
451  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
452  !getLangOpts().CPlusPlus11) {
453  // C++03 [basic.lookup.classref]p1:
454  // [...] If the lookup in the class of the object expression finds a
455  // template, the name is also looked up in the context of the entire
456  // postfix-expression and [...]
457  //
458  // Note: C++11 does not perform this second lookup.
459  LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
460  LookupOrdinaryName);
461  LookupName(FoundOuter, S);
462  FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
463 
464  if (FoundOuter.empty()) {
465  // - if the name is not found, the name found in the class of the
466  // object expression is used, otherwise
467  } else if (!FoundOuter.getAsSingle<ClassTemplateDecl>() ||
468  FoundOuter.isAmbiguous()) {
469  // - if the name is found in the context of the entire
470  // postfix-expression and does not name a class template, the name
471  // found in the class of the object expression is used, otherwise
472  FoundOuter.clear();
473  } else if (!Found.isSuppressingDiagnostics()) {
474  // - if the name found is a class template, it must refer to the same
475  // entity as the one found in the class of the object expression,
476  // otherwise the program is ill-formed.
477  if (!Found.isSingleResult() ||
478  Found.getFoundDecl()->getCanonicalDecl()
479  != FoundOuter.getFoundDecl()->getCanonicalDecl()) {
480  Diag(Found.getNameLoc(),
481  diag::ext_nested_name_member_ref_lookup_ambiguous)
482  << Found.getLookupName()
483  << ObjectType;
485  diag::note_ambig_member_ref_object_type)
486  << ObjectType;
487  Diag(FoundOuter.getFoundDecl()->getLocation(),
488  diag::note_ambig_member_ref_scope);
489 
490  // Recover by taking the template that we found in the object
491  // expression's type.
492  }
493  }
494  }
495 
496  return false;
497 }
498 
500  SourceLocation Less,
501  SourceLocation Greater) {
502  if (TemplateName.isInvalid())
503  return;
504 
505  DeclarationNameInfo NameInfo;
506  CXXScopeSpec SS;
507  LookupNameKind LookupKind;
508 
509  DeclContext *LookupCtx = nullptr;
510  NamedDecl *Found = nullptr;
511  bool MissingTemplateKeyword = false;
512 
513  // Figure out what name we looked up.
514  if (auto *DRE = dyn_cast<DeclRefExpr>(TemplateName.get())) {
515  NameInfo = DRE->getNameInfo();
516  SS.Adopt(DRE->getQualifierLoc());
517  LookupKind = LookupOrdinaryName;
518  Found = DRE->getFoundDecl();
519  } else if (auto *ME = dyn_cast<MemberExpr>(TemplateName.get())) {
520  NameInfo = ME->getMemberNameInfo();
521  SS.Adopt(ME->getQualifierLoc());
522  LookupKind = LookupMemberName;
523  LookupCtx = ME->getBase()->getType()->getAsCXXRecordDecl();
524  Found = ME->getMemberDecl();
525  } else if (auto *DSDRE =
526  dyn_cast<DependentScopeDeclRefExpr>(TemplateName.get())) {
527  NameInfo = DSDRE->getNameInfo();
528  SS.Adopt(DSDRE->getQualifierLoc());
529  MissingTemplateKeyword = true;
530  } else if (auto *DSME =
531  dyn_cast<CXXDependentScopeMemberExpr>(TemplateName.get())) {
532  NameInfo = DSME->getMemberNameInfo();
533  SS.Adopt(DSME->getQualifierLoc());
534  MissingTemplateKeyword = true;
535  } else {
536  llvm_unreachable("unexpected kind of potential template name");
537  }
538 
539  // If this is a dependent-scope lookup, diagnose that the 'template' keyword
540  // was missing.
541  if (MissingTemplateKeyword) {
542  Diag(NameInfo.getBeginLoc(), diag::err_template_kw_missing)
543  << "" << NameInfo.getName().getAsString() << SourceRange(Less, Greater);
544  return;
545  }
546 
547  // Try to correct the name by looking for templates and C++ named casts.
548  struct TemplateCandidateFilter : CorrectionCandidateCallback {
549  TemplateCandidateFilter() {
550  WantTypeSpecifiers = false;
551  WantExpressionKeywords = false;
552  WantRemainingKeywords = false;
553  WantCXXNamedCasts = true;
554  };
555  bool ValidateCandidate(const TypoCorrection &Candidate) override {
556  if (auto *ND = Candidate.getCorrectionDecl())
557  return isAcceptableTemplateName(ND->getASTContext(), ND, true);
558  return Candidate.isKeyword();
559  }
560  };
561 
562  DeclarationName Name = NameInfo.getName();
563  if (TypoCorrection Corrected =
564  CorrectTypo(NameInfo, LookupKind, S, &SS,
565  llvm::make_unique<TemplateCandidateFilter>(),
566  CTK_ErrorRecovery, LookupCtx)) {
567  auto *ND = Corrected.getFoundDecl();
568  if (ND)
569  ND = isAcceptableTemplateName(Context, ND,
570  /*AllowFunctionTemplates*/ true);
571  if (ND || Corrected.isKeyword()) {
572  if (LookupCtx) {
573  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
574  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
575  Name.getAsString() == CorrectedStr;
576  diagnoseTypo(Corrected,
577  PDiag(diag::err_non_template_in_member_template_id_suggest)
578  << Name << LookupCtx << DroppedSpecifier
579  << SS.getRange(), false);
580  } else {
581  diagnoseTypo(Corrected,
582  PDiag(diag::err_non_template_in_template_id_suggest)
583  << Name, false);
584  }
585  if (Found)
586  Diag(Found->getLocation(),
587  diag::note_non_template_in_template_id_found);
588  return;
589  }
590  }
591 
592  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
593  << Name << SourceRange(Less, Greater);
594  if (Found)
595  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
596 }
597 
598 /// ActOnDependentIdExpression - Handle a dependent id-expression that
599 /// was just parsed. This is only possible with an explicit scope
600 /// specifier naming a dependent type.
603  SourceLocation TemplateKWLoc,
604  const DeclarationNameInfo &NameInfo,
605  bool isAddressOfOperand,
606  const TemplateArgumentListInfo *TemplateArgs) {
607  DeclContext *DC = getFunctionLevelDeclContext();
608 
609  // C++11 [expr.prim.general]p12:
610  // An id-expression that denotes a non-static data member or non-static
611  // member function of a class can only be used:
612  // (...)
613  // - if that id-expression denotes a non-static data member and it
614  // appears in an unevaluated operand.
615  //
616  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
617  // CXXDependentScopeMemberExpr. The former can instantiate to either
618  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
619  // always a MemberExpr.
620  bool MightBeCxx11UnevalField =
621  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
622 
623  // Check if the nested name specifier is an enum type.
624  bool IsEnum = false;
625  if (NestedNameSpecifier *NNS = SS.getScopeRep())
626  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
627 
628  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
629  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
630  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
631 
632  // Since the 'this' expression is synthesized, we don't need to
633  // perform the double-lookup check.
634  NamedDecl *FirstQualifierInScope = nullptr;
635 
637  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
638  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
639  FirstQualifierInScope, NameInfo, TemplateArgs);
640  }
641 
642  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
643 }
644 
647  SourceLocation TemplateKWLoc,
648  const DeclarationNameInfo &NameInfo,
649  const TemplateArgumentListInfo *TemplateArgs) {
651  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
652  TemplateArgs);
653 }
654 
655 
656 /// Determine whether we would be unable to instantiate this template (because
657 /// it either has no definition, or is in the process of being instantiated).
659  NamedDecl *Instantiation,
660  bool InstantiatedFromMember,
661  const NamedDecl *Pattern,
662  const NamedDecl *PatternDef,
664  bool Complain /*= true*/) {
665  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
666  isa<VarDecl>(Instantiation));
667 
668  bool IsEntityBeingDefined = false;
669  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
670  IsEntityBeingDefined = TD->isBeingDefined();
671 
672  if (PatternDef && !IsEntityBeingDefined) {
673  NamedDecl *SuggestedDef = nullptr;
674  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
675  /*OnlyNeedComplete*/false)) {
676  // If we're allowed to diagnose this and recover, do so.
677  bool Recover = Complain && !isSFINAEContext();
678  if (Complain)
679  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
681  return !Recover;
682  }
683  return false;
684  }
685 
686  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
687  return true;
688 
690  QualType InstantiationTy;
691  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
692  InstantiationTy = Context.getTypeDeclType(TD);
693  if (PatternDef) {
694  Diag(PointOfInstantiation,
695  diag::err_template_instantiate_within_definition)
696  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
697  << InstantiationTy;
698  // Not much point in noting the template declaration here, since
699  // we're lexically inside it.
700  Instantiation->setInvalidDecl();
701  } else if (InstantiatedFromMember) {
702  if (isa<FunctionDecl>(Instantiation)) {
703  Diag(PointOfInstantiation,
704  diag::err_explicit_instantiation_undefined_member)
705  << /*member function*/ 1 << Instantiation->getDeclName()
706  << Instantiation->getDeclContext();
707  Note = diag::note_explicit_instantiation_here;
708  } else {
709  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
710  Diag(PointOfInstantiation,
711  diag::err_implicit_instantiate_member_undefined)
712  << InstantiationTy;
713  Note = diag::note_member_declared_at;
714  }
715  } else {
716  if (isa<FunctionDecl>(Instantiation)) {
717  Diag(PointOfInstantiation,
718  diag::err_explicit_instantiation_undefined_func_template)
719  << Pattern;
720  Note = diag::note_explicit_instantiation_here;
721  } else if (isa<TagDecl>(Instantiation)) {
722  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
723  << (TSK != TSK_ImplicitInstantiation)
724  << InstantiationTy;
725  Note = diag::note_template_decl_here;
726  } else {
727  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
728  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
729  Diag(PointOfInstantiation,
730  diag::err_explicit_instantiation_undefined_var_template)
731  << Instantiation;
732  Instantiation->setInvalidDecl();
733  } else
734  Diag(PointOfInstantiation,
735  diag::err_explicit_instantiation_undefined_member)
736  << /*static data member*/ 2 << Instantiation->getDeclName()
737  << Instantiation->getDeclContext();
738  Note = diag::note_explicit_instantiation_here;
739  }
740  }
741  if (Note) // Diagnostics were emitted.
742  Diag(Pattern->getLocation(), Note.getValue());
743 
744  // In general, Instantiation isn't marked invalid to get more than one
745  // error for multiple undefined instantiations. But the code that does
746  // explicit declaration -> explicit definition conversion can't handle
747  // invalid declarations, so mark as invalid in that case.
749  Instantiation->setInvalidDecl();
750  return true;
751 }
752 
753 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
754 /// that the template parameter 'PrevDecl' is being shadowed by a new
755 /// declaration at location Loc. Returns true to indicate that this is
756 /// an error, and false otherwise.
758  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
759 
760  // Microsoft Visual C++ permits template parameters to be shadowed.
761  if (getLangOpts().MicrosoftExt)
762  return;
763 
764  // C++ [temp.local]p4:
765  // A template-parameter shall not be redeclared within its
766  // scope (including nested scopes).
767  Diag(Loc, diag::err_template_param_shadow)
768  << cast<NamedDecl>(PrevDecl)->getDeclName();
769  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
770 }
771 
772 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
773 /// the parameter D to reference the templated declaration and return a pointer
774 /// to the template declaration. Otherwise, do nothing to D and return null.
776  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
777  D = Temp->getTemplatedDecl();
778  return Temp;
779  }
780  return nullptr;
781 }
782 
784  SourceLocation EllipsisLoc) const {
785  assert(Kind == Template &&
786  "Only template template arguments can be pack expansions here");
787  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
788  "Template template argument pack expansion without packs");
789  ParsedTemplateArgument Result(*this);
790  Result.EllipsisLoc = EllipsisLoc;
791  return Result;
792 }
793 
795  const ParsedTemplateArgument &Arg) {
796 
797  switch (Arg.getKind()) {
799  TypeSourceInfo *DI;
800  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
801  if (!DI)
802  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
803  return TemplateArgumentLoc(TemplateArgument(T), DI);
804  }
805 
807  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
809  }
810 
812  TemplateName Template = Arg.getAsTemplate().get();
813  TemplateArgument TArg;
814  if (Arg.getEllipsisLoc().isValid())
815  TArg = TemplateArgument(Template, Optional<unsigned int>());
816  else
817  TArg = Template;
818  return TemplateArgumentLoc(TArg,
820  SemaRef.Context),
821  Arg.getLocation(),
822  Arg.getEllipsisLoc());
823  }
824  }
825 
826  llvm_unreachable("Unhandled parsed template argument");
827 }
828 
829 /// Translates template arguments as provided by the parser
830 /// into template arguments used by semantic analysis.
832  TemplateArgumentListInfo &TemplateArgs) {
833  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
834  TemplateArgs.addArgument(translateTemplateArgument(*this,
835  TemplateArgsIn[I]));
836 }
837 
839  SourceLocation Loc,
840  IdentifierInfo *Name) {
841  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
843  if (PrevDecl && PrevDecl->isTemplateParameter())
844  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
845 }
846 
847 /// Convert a parsed type into a parsed template argument. This is mostly
848 /// trivial, except that we may have parsed a C++17 deduced class template
849 /// specialization type, in which case we should form a template template
850 /// argument instead of a type template argument.
852  TypeSourceInfo *TInfo;
853  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
854  if (T.isNull())
855  return ParsedTemplateArgument();
856  assert(TInfo && "template argument with no location");
857 
858  // If we might have formed a deduced template specialization type, convert
859  // it to a template template argument.
860  if (getLangOpts().CPlusPlus17) {
861  TypeLoc TL = TInfo->getTypeLoc();
862  SourceLocation EllipsisLoc;
863  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
864  EllipsisLoc = PET.getEllipsisLoc();
865  TL = PET.getPatternLoc();
866  }
867 
868  CXXScopeSpec SS;
869  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
870  SS.Adopt(ET.getQualifierLoc());
871  TL = ET.getNamedTypeLoc();
872  }
873 
874  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
875  TemplateName Name = DTST.getTypePtr()->getTemplateName();
876  if (SS.isSet())
877  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
878  /*HasTemplateKeyword*/ false,
879  Name.getAsTemplateDecl());
880  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
881  DTST.getTemplateNameLoc());
882  if (EllipsisLoc.isValid())
883  Result = Result.getTemplatePackExpansion(EllipsisLoc);
884  return Result;
885  }
886  }
887 
888  // This is a normal type template argument. Note, if the type template
889  // argument is an injected-class-name for a template, it has a dual nature
890  // and can be used as either a type or a template. We handle that in
891  // convertTypeTemplateArgumentToTemplate.
893  ParsedType.get().getAsOpaquePtr(),
894  TInfo->getTypeLoc().getBeginLoc());
895 }
896 
897 /// ActOnTypeParameter - Called when a C++ template type parameter
898 /// (e.g., "typename T") has been parsed. Typename specifies whether
899 /// the keyword "typename" was used to declare the type parameter
900 /// (otherwise, "class" was used), and KeyLoc is the location of the
901 /// "class" or "typename" keyword. ParamName is the name of the
902 /// parameter (NULL indicates an unnamed template parameter) and
903 /// ParamNameLoc is the location of the parameter name (if any).
904 /// If the type parameter has a default argument, it will be added
905 /// later via ActOnTypeParameterDefault.
907  SourceLocation EllipsisLoc,
908  SourceLocation KeyLoc,
909  IdentifierInfo *ParamName,
910  SourceLocation ParamNameLoc,
911  unsigned Depth, unsigned Position,
912  SourceLocation EqualLoc,
913  ParsedType DefaultArg) {
914  assert(S->isTemplateParamScope() &&
915  "Template type parameter not in template parameter scope!");
916 
917  SourceLocation Loc = ParamNameLoc;
918  if (!ParamName)
919  Loc = KeyLoc;
920 
921  bool IsParameterPack = EllipsisLoc.isValid();
922  TemplateTypeParmDecl *Param
924  KeyLoc, Loc, Depth, Position, ParamName,
925  Typename, IsParameterPack);
926  Param->setAccess(AS_public);
927 
928  if (ParamName) {
929  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
930 
931  // Add the template parameter into the current scope.
932  S->AddDecl(Param);
933  IdResolver.AddDecl(Param);
934  }
935 
936  // C++0x [temp.param]p9:
937  // A default template-argument may be specified for any kind of
938  // template-parameter that is not a template parameter pack.
939  if (DefaultArg && IsParameterPack) {
940  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
941  DefaultArg = nullptr;
942  }
943 
944  // Handle the default argument, if provided.
945  if (DefaultArg) {
946  TypeSourceInfo *DefaultTInfo;
947  GetTypeFromParser(DefaultArg, &DefaultTInfo);
948 
949  assert(DefaultTInfo && "expected source information for type");
950 
951  // Check for unexpanded parameter packs.
952  if (DiagnoseUnexpandedParameterPack(Loc, DefaultTInfo,
953  UPPC_DefaultArgument))
954  return Param;
955 
956  // Check the template argument itself.
957  if (CheckTemplateArgument(Param, DefaultTInfo)) {
958  Param->setInvalidDecl();
959  return Param;
960  }
961 
962  Param->setDefaultArgument(DefaultTInfo);
963  }
964 
965  return Param;
966 }
967 
968 /// Check that the type of a non-type template parameter is
969 /// well-formed.
970 ///
971 /// \returns the (possibly-promoted) parameter type if valid;
972 /// otherwise, produces a diagnostic and returns a NULL type.
974  SourceLocation Loc) {
975  if (TSI->getType()->isUndeducedType()) {
976  // C++17 [temp.dep.expr]p3:
977  // An id-expression is type-dependent if it contains
978  // - an identifier associated by name lookup with a non-type
979  // template-parameter declared with a type that contains a
980  // placeholder type (7.1.7.4),
981  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
982  }
983 
984  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
985 }
986 
988  SourceLocation Loc) {
989  // We don't allow variably-modified types as the type of non-type template
990  // parameters.
991  if (T->isVariablyModifiedType()) {
992  Diag(Loc, diag::err_variably_modified_nontype_template_param)
993  << T;
994  return QualType();
995  }
996 
997  // C++ [temp.param]p4:
998  //
999  // A non-type template-parameter shall have one of the following
1000  // (optionally cv-qualified) types:
1001  //
1002  // -- integral or enumeration type,
1003  if (T->isIntegralOrEnumerationType() ||
1004  // -- pointer to object or pointer to function,
1005  T->isPointerType() ||
1006  // -- reference to object or reference to function,
1007  T->isReferenceType() ||
1008  // -- pointer to member,
1009  T->isMemberPointerType() ||
1010  // -- std::nullptr_t.
1011  T->isNullPtrType() ||
1012  // If T is a dependent type, we can't do the check now, so we
1013  // assume that it is well-formed.
1014  T->isDependentType() ||
1015  // Allow use of auto in template parameter declarations.
1016  T->isUndeducedType()) {
1017  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1018  // are ignored when determining its type.
1019  return T.getUnqualifiedType();
1020  }
1021 
1022  // C++ [temp.param]p8:
1023  //
1024  // A non-type template-parameter of type "array of T" or
1025  // "function returning T" is adjusted to be of type "pointer to
1026  // T" or "pointer to function returning T", respectively.
1027  else if (T->isArrayType() || T->isFunctionType())
1028  return Context.getDecayedType(T);
1029 
1030  Diag(Loc, diag::err_template_nontype_parm_bad_type)
1031  << T;
1032 
1033  return QualType();
1034 }
1035 
1037  unsigned Depth,
1038  unsigned Position,
1039  SourceLocation EqualLoc,
1040  Expr *Default) {
1041  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1042 
1043  // Check that we have valid decl-specifiers specified.
1044  auto CheckValidDeclSpecifiers = [this, &D] {
1045  // C++ [temp.param]
1046  // p1
1047  // template-parameter:
1048  // ...
1049  // parameter-declaration
1050  // p2
1051  // ... A storage class shall not be specified in a template-parameter
1052  // declaration.
1053  // [dcl.typedef]p1:
1054  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1055  // of a parameter-declaration
1056  const DeclSpec &DS = D.getDeclSpec();
1057  auto EmitDiag = [this](SourceLocation Loc) {
1058  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1059  << FixItHint::CreateRemoval(Loc);
1060  };
1062  EmitDiag(DS.getStorageClassSpecLoc());
1063 
1065  EmitDiag(DS.getThreadStorageClassSpecLoc());
1066 
1067  // [dcl.inline]p1:
1068  // The inline specifier can be applied only to the declaration or
1069  // definition of a variable or function.
1070 
1071  if (DS.isInlineSpecified())
1072  EmitDiag(DS.getInlineSpecLoc());
1073 
1074  // [dcl.constexpr]p1:
1075  // The constexpr specifier shall be applied only to the definition of a
1076  // variable or variable template or the declaration of a function or
1077  // function template.
1078 
1079  if (DS.isConstexprSpecified())
1080  EmitDiag(DS.getConstexprSpecLoc());
1081 
1082  // [dcl.fct.spec]p1:
1083  // Function-specifiers can be used only in function declarations.
1084 
1085  if (DS.isVirtualSpecified())
1086  EmitDiag(DS.getVirtualSpecLoc());
1087 
1088  if (DS.isExplicitSpecified())
1089  EmitDiag(DS.getExplicitSpecLoc());
1090 
1091  if (DS.isNoreturnSpecified())
1092  EmitDiag(DS.getNoreturnSpecLoc());
1093  };
1094 
1095  CheckValidDeclSpecifiers();
1096 
1097  if (TInfo->getType()->isUndeducedType()) {
1098  Diag(D.getIdentifierLoc(),
1099  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1100  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1101  }
1102 
1103  assert(S->isTemplateParamScope() &&
1104  "Non-type template parameter not in template parameter scope!");
1105  bool Invalid = false;
1106 
1107  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1108  if (T.isNull()) {
1109  T = Context.IntTy; // Recover with an 'int' type.
1110  Invalid = true;
1111  }
1112 
1113  IdentifierInfo *ParamName = D.getIdentifier();
1114  bool IsParameterPack = D.hasEllipsis();
1116  Context, Context.getTranslationUnitDecl(), D.getBeginLoc(),
1117  D.getIdentifierLoc(), Depth, Position, ParamName, T, IsParameterPack,
1118  TInfo);
1119  Param->setAccess(AS_public);
1120 
1121  if (Invalid)
1122  Param->setInvalidDecl();
1123 
1124  if (ParamName) {
1126  ParamName);
1127 
1128  // Add the template parameter into the current scope.
1129  S->AddDecl(Param);
1130  IdResolver.AddDecl(Param);
1131  }
1132 
1133  // C++0x [temp.param]p9:
1134  // A default template-argument may be specified for any kind of
1135  // template-parameter that is not a template parameter pack.
1136  if (Default && IsParameterPack) {
1137  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1138  Default = nullptr;
1139  }
1140 
1141  // Check the well-formedness of the default template argument, if provided.
1142  if (Default) {
1143  // Check for unexpanded parameter packs.
1144  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1145  return Param;
1146 
1147  TemplateArgument Converted;
1148  ExprResult DefaultRes =
1149  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1150  if (DefaultRes.isInvalid()) {
1151  Param->setInvalidDecl();
1152  return Param;
1153  }
1154  Default = DefaultRes.get();
1155 
1156  Param->setDefaultArgument(Default);
1157  }
1158 
1159  return Param;
1160 }
1161 
1162 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1163 /// parameter (e.g. T in template <template <typename> class T> class array)
1164 /// has been parsed. S is the current scope.
1166  SourceLocation TmpLoc,
1167  TemplateParameterList *Params,
1168  SourceLocation EllipsisLoc,
1169  IdentifierInfo *Name,
1170  SourceLocation NameLoc,
1171  unsigned Depth,
1172  unsigned Position,
1173  SourceLocation EqualLoc,
1174  ParsedTemplateArgument Default) {
1175  assert(S->isTemplateParamScope() &&
1176  "Template template parameter not in template parameter scope!");
1177 
1178  // Construct the parameter object.
1179  bool IsParameterPack = EllipsisLoc.isValid();
1180  TemplateTemplateParmDecl *Param =
1182  NameLoc.isInvalid()? TmpLoc : NameLoc,
1183  Depth, Position, IsParameterPack,
1184  Name, Params);
1185  Param->setAccess(AS_public);
1186 
1187  // If the template template parameter has a name, then link the identifier
1188  // into the scope and lookup mechanisms.
1189  if (Name) {
1190  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1191 
1192  S->AddDecl(Param);
1193  IdResolver.AddDecl(Param);
1194  }
1195 
1196  if (Params->size() == 0) {
1197  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1198  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1199  Param->setInvalidDecl();
1200  }
1201 
1202  // C++0x [temp.param]p9:
1203  // A default template-argument may be specified for any kind of
1204  // template-parameter that is not a template parameter pack.
1205  if (IsParameterPack && !Default.isInvalid()) {
1206  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1207  Default = ParsedTemplateArgument();
1208  }
1209 
1210  if (!Default.isInvalid()) {
1211  // Check only that we have a template template argument. We don't want to
1212  // try to check well-formedness now, because our template template parameter
1213  // might have dependent types in its template parameters, which we wouldn't
1214  // be able to match now.
1215  //
1216  // If none of the template template parameter's template arguments mention
1217  // other template parameters, we could actually perform more checking here.
1218  // However, it isn't worth doing.
1219  TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
1220  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1221  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1222  << DefaultArg.getSourceRange();
1223  return Param;
1224  }
1225 
1226  // Check for unexpanded parameter packs.
1227  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1228  DefaultArg.getArgument().getAsTemplate(),
1229  UPPC_DefaultArgument))
1230  return Param;
1231 
1232  Param->setDefaultArgument(Context, DefaultArg);
1233  }
1234 
1235  return Param;
1236 }
1237 
1238 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1239 /// constrained by RequiresClause, that contains the template parameters in
1240 /// Params.
1243  SourceLocation ExportLoc,
1244  SourceLocation TemplateLoc,
1245  SourceLocation LAngleLoc,
1246  ArrayRef<NamedDecl *> Params,
1247  SourceLocation RAngleLoc,
1248  Expr *RequiresClause) {
1249  if (ExportLoc.isValid())
1250  Diag(ExportLoc, diag::warn_template_export_unsupported);
1251 
1253  Context, TemplateLoc, LAngleLoc,
1254  llvm::makeArrayRef(Params.data(), Params.size()),
1255  RAngleLoc, RequiresClause);
1256 }
1257 
1258 static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
1259  if (SS.isSet())
1261 }
1262 
1264  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1265  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1266  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1267  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1268  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1269  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1270  assert(TemplateParams && TemplateParams->size() > 0 &&
1271  "No template parameters");
1272  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1273  bool Invalid = false;
1274 
1275  // Check that we can declare a template here.
1276  if (CheckTemplateDeclScope(S, TemplateParams))
1277  return true;
1278 
1280  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1281 
1282  // There is no such thing as an unnamed class template.
1283  if (!Name) {
1284  Diag(KWLoc, diag::err_template_unnamed_class);
1285  return true;
1286  }
1287 
1288  // Find any previous declaration with this name. For a friend with no
1289  // scope explicitly specified, we only look for tag declarations (per
1290  // C++11 [basic.lookup.elab]p2).
1291  DeclContext *SemanticContext;
1292  LookupResult Previous(*this, Name, NameLoc,
1293  (SS.isEmpty() && TUK == TUK_Friend)
1294  ? LookupTagName : LookupOrdinaryName,
1295  forRedeclarationInCurContext());
1296  if (SS.isNotEmpty() && !SS.isInvalid()) {
1297  SemanticContext = computeDeclContext(SS, true);
1298  if (!SemanticContext) {
1299  // FIXME: Horrible, horrible hack! We can't currently represent this
1300  // in the AST, and historically we have just ignored such friend
1301  // class templates, so don't complain here.
1302  Diag(NameLoc, TUK == TUK_Friend
1303  ? diag::warn_template_qualified_friend_ignored
1304  : diag::err_template_qualified_declarator_no_match)
1305  << SS.getScopeRep() << SS.getRange();
1306  return TUK != TUK_Friend;
1307  }
1308 
1309  if (RequireCompleteDeclContext(SS, SemanticContext))
1310  return true;
1311 
1312  // If we're adding a template to a dependent context, we may need to
1313  // rebuilding some of the types used within the template parameter list,
1314  // now that we know what the current instantiation is.
1315  if (SemanticContext->isDependentContext()) {
1316  ContextRAII SavedContext(*this, SemanticContext);
1317  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1318  Invalid = true;
1319  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1320  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1321 
1322  LookupQualifiedName(Previous, SemanticContext);
1323  } else {
1324  SemanticContext = CurContext;
1325 
1326  // C++14 [class.mem]p14:
1327  // If T is the name of a class, then each of the following shall have a
1328  // name different from T:
1329  // -- every member template of class T
1330  if (TUK != TUK_Friend &&
1331  DiagnoseClassNameShadow(SemanticContext,
1332  DeclarationNameInfo(Name, NameLoc)))
1333  return true;
1334 
1335  LookupName(Previous, S);
1336  }
1337 
1338  if (Previous.isAmbiguous())
1339  return true;
1340 
1341  NamedDecl *PrevDecl = nullptr;
1342  if (Previous.begin() != Previous.end())
1343  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1344 
1345  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1346  // Maybe we will complain about the shadowed template parameter.
1347  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1348  // Just pretend that we didn't see the previous declaration.
1349  PrevDecl = nullptr;
1350  }
1351 
1352  // If there is a previous declaration with the same name, check
1353  // whether this is a valid redeclaration.
1354  ClassTemplateDecl *PrevClassTemplate =
1355  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1356 
1357  // We may have found the injected-class-name of a class template,
1358  // class template partial specialization, or class template specialization.
1359  // In these cases, grab the template that is being defined or specialized.
1360  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1361  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1362  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1363  PrevClassTemplate
1364  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1365  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1366  PrevClassTemplate
1367  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1368  ->getSpecializedTemplate();
1369  }
1370  }
1371 
1372  if (TUK == TUK_Friend) {
1373  // C++ [namespace.memdef]p3:
1374  // [...] When looking for a prior declaration of a class or a function
1375  // declared as a friend, and when the name of the friend class or
1376  // function is neither a qualified name nor a template-id, scopes outside
1377  // the innermost enclosing namespace scope are not considered.
1378  if (!SS.isSet()) {
1379  DeclContext *OutermostContext = CurContext;
1380  while (!OutermostContext->isFileContext())
1381  OutermostContext = OutermostContext->getLookupParent();
1382 
1383  if (PrevDecl &&
1384  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1385  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1386  SemanticContext = PrevDecl->getDeclContext();
1387  } else {
1388  // Declarations in outer scopes don't matter. However, the outermost
1389  // context we computed is the semantic context for our new
1390  // declaration.
1391  PrevDecl = PrevClassTemplate = nullptr;
1392  SemanticContext = OutermostContext;
1393 
1394  // Check that the chosen semantic context doesn't already contain a
1395  // declaration of this name as a non-tag type.
1396  Previous.clear(LookupOrdinaryName);
1397  DeclContext *LookupContext = SemanticContext;
1398  while (LookupContext->isTransparentContext())
1399  LookupContext = LookupContext->getLookupParent();
1400  LookupQualifiedName(Previous, LookupContext);
1401 
1402  if (Previous.isAmbiguous())
1403  return true;
1404 
1405  if (Previous.begin() != Previous.end())
1406  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1407  }
1408  }
1409  } else if (PrevDecl &&
1410  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1411  S, SS.isValid()))
1412  PrevDecl = PrevClassTemplate = nullptr;
1413 
1414  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1415  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1416  if (SS.isEmpty() &&
1417  !(PrevClassTemplate &&
1418  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1419  SemanticContext->getRedeclContext()))) {
1420  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1421  Diag(Shadow->getTargetDecl()->getLocation(),
1422  diag::note_using_decl_target);
1423  Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1424  // Recover by ignoring the old declaration.
1425  PrevDecl = PrevClassTemplate = nullptr;
1426  }
1427  }
1428 
1429  // TODO Memory management; associated constraints are not always stored.
1430  Expr *const CurAC = formAssociatedConstraints(TemplateParams, nullptr);
1431 
1432  if (PrevClassTemplate) {
1433  // Ensure that the template parameter lists are compatible. Skip this check
1434  // for a friend in a dependent context: the template parameter list itself
1435  // could be dependent.
1436  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1437  !TemplateParameterListsAreEqual(TemplateParams,
1438  PrevClassTemplate->getTemplateParameters(),
1439  /*Complain=*/true,
1440  TPL_TemplateMatch))
1441  return true;
1442 
1443  // Check for matching associated constraints on redeclarations.
1444  const Expr *const PrevAC = PrevClassTemplate->getAssociatedConstraints();
1445  const bool RedeclACMismatch = [&] {
1446  if (!(CurAC || PrevAC))
1447  return false; // Nothing to check; no mismatch.
1448  if (CurAC && PrevAC) {
1449  llvm::FoldingSetNodeID CurACInfo, PrevACInfo;
1450  CurAC->Profile(CurACInfo, Context, /*Canonical=*/true);
1451  PrevAC->Profile(PrevACInfo, Context, /*Canonical=*/true);
1452  if (CurACInfo == PrevACInfo)
1453  return false; // All good; no mismatch.
1454  }
1455  return true;
1456  }();
1457 
1458  if (RedeclACMismatch) {
1459  Diag(CurAC ? CurAC->getBeginLoc() : NameLoc,
1460  diag::err_template_different_associated_constraints);
1461  Diag(PrevAC ? PrevAC->getBeginLoc() : PrevClassTemplate->getLocation(),
1462  diag::note_template_prev_declaration)
1463  << /*declaration*/ 0;
1464  return true;
1465  }
1466 
1467  // C++ [temp.class]p4:
1468  // In a redeclaration, partial specialization, explicit
1469  // specialization or explicit instantiation of a class template,
1470  // the class-key shall agree in kind with the original class
1471  // template declaration (7.1.5.3).
1472  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1473  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1474  TUK == TUK_Definition, KWLoc, Name)) {
1475  Diag(KWLoc, diag::err_use_with_wrong_tag)
1476  << Name
1477  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1478  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1479  Kind = PrevRecordDecl->getTagKind();
1480  }
1481 
1482  // Check for redefinition of this class template.
1483  if (TUK == TUK_Definition) {
1484  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1485  // If we have a prior definition that is not visible, treat this as
1486  // simply making that previous definition visible.
1487  NamedDecl *Hidden = nullptr;
1488  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1489  SkipBody->ShouldSkip = true;
1490  SkipBody->Previous = Def;
1491  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1492  assert(Tmpl && "original definition of a class template is not a "
1493  "class template?");
1494  makeMergedDefinitionVisible(Hidden);
1495  makeMergedDefinitionVisible(Tmpl);
1496  } else {
1497  Diag(NameLoc, diag::err_redefinition) << Name;
1498  Diag(Def->getLocation(), diag::note_previous_definition);
1499  // FIXME: Would it make sense to try to "forget" the previous
1500  // definition, as part of error recovery?
1501  return true;
1502  }
1503  }
1504  }
1505  } else if (PrevDecl) {
1506  // C++ [temp]p5:
1507  // A class template shall not have the same name as any other
1508  // template, class, function, object, enumeration, enumerator,
1509  // namespace, or type in the same scope (3.3), except as specified
1510  // in (14.5.4).
1511  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1512  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1513  return true;
1514  }
1515 
1516  // Check the template parameter list of this declaration, possibly
1517  // merging in the template parameter list from the previous class
1518  // template declaration. Skip this check for a friend in a dependent
1519  // context, because the template parameter list might be dependent.
1520  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1521  CheckTemplateParameterList(
1522  TemplateParams,
1523  PrevClassTemplate
1524  ? PrevClassTemplate->getMostRecentDecl()->getTemplateParameters()
1525  : nullptr,
1526  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1527  SemanticContext->isDependentContext())
1528  ? TPC_ClassTemplateMember
1529  : TUK == TUK_Friend ? TPC_FriendClassTemplate : TPC_ClassTemplate,
1530  SkipBody))
1531  Invalid = true;
1532 
1533  if (SS.isSet()) {
1534  // If the name of the template was qualified, we must be defining the
1535  // template out-of-line.
1536  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1537  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1538  : diag::err_member_decl_does_not_match)
1539  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1540  Invalid = true;
1541  }
1542  }
1543 
1544  // If this is a templated friend in a dependent context we should not put it
1545  // on the redecl chain. In some cases, the templated friend can be the most
1546  // recent declaration tricking the template instantiator to make substitutions
1547  // there.
1548  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1549  bool ShouldAddRedecl
1550  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1551 
1552  CXXRecordDecl *NewClass =
1553  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1554  PrevClassTemplate && ShouldAddRedecl ?
1555  PrevClassTemplate->getTemplatedDecl() : nullptr,
1556  /*DelayTypeCreation=*/true);
1557  SetNestedNameSpecifier(NewClass, SS);
1558  if (NumOuterTemplateParamLists > 0)
1560  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1561  NumOuterTemplateParamLists));
1562 
1563  // Add alignment attributes if necessary; these attributes are checked when
1564  // the ASTContext lays out the structure.
1565  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
1566  AddAlignmentAttributesForRecord(NewClass);
1567  AddMsStructLayoutForRecord(NewClass);
1568  }
1569 
1570  // Attach the associated constraints when the declaration will not be part of
1571  // a decl chain.
1572  Expr *const ACtoAttach =
1573  PrevClassTemplate && ShouldAddRedecl ? nullptr : CurAC;
1574 
1575  ClassTemplateDecl *NewTemplate
1576  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1577  DeclarationName(Name), TemplateParams,
1578  NewClass, ACtoAttach);
1579 
1580  if (ShouldAddRedecl)
1581  NewTemplate->setPreviousDecl(PrevClassTemplate);
1582 
1583  NewClass->setDescribedClassTemplate(NewTemplate);
1584 
1585  if (ModulePrivateLoc.isValid())
1586  NewTemplate->setModulePrivate();
1587 
1588  // Build the type for the class template declaration now.
1589  QualType T = NewTemplate->getInjectedClassNameSpecialization();
1590  T = Context.getInjectedClassNameType(NewClass, T);
1591  assert(T->isDependentType() && "Class template type is not dependent?");
1592  (void)T;
1593 
1594  // If we are providing an explicit specialization of a member that is a
1595  // class template, make a note of that.
1596  if (PrevClassTemplate &&
1597  PrevClassTemplate->getInstantiatedFromMemberTemplate())
1598  PrevClassTemplate->setMemberSpecialization();
1599 
1600  // Set the access specifier.
1601  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1602  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1603 
1604  // Set the lexical context of these templates
1605  NewClass->setLexicalDeclContext(CurContext);
1606  NewTemplate->setLexicalDeclContext(CurContext);
1607 
1608  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
1609  NewClass->startDefinition();
1610 
1611  ProcessDeclAttributeList(S, NewClass, Attr);
1612 
1613  if (PrevClassTemplate)
1614  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1615 
1616  AddPushedVisibilityAttribute(NewClass);
1617 
1618  if (TUK != TUK_Friend) {
1619  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
1620  Scope *Outer = S;
1621  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
1622  Outer = Outer->getParent();
1623  PushOnScopeChains(NewTemplate, Outer);
1624  } else {
1625  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1626  NewTemplate->setAccess(PrevClassTemplate->getAccess());
1627  NewClass->setAccess(PrevClassTemplate->getAccess());
1628  }
1629 
1630  NewTemplate->setObjectOfFriendDecl();
1631 
1632  // Friend templates are visible in fairly strange ways.
1633  if (!CurContext->isDependentContext()) {
1634  DeclContext *DC = SemanticContext->getRedeclContext();
1635  DC->makeDeclVisibleInContext(NewTemplate);
1636  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1637  PushOnScopeChains(NewTemplate, EnclosingScope,
1638  /* AddToContext = */ false);
1639  }
1640 
1641  FriendDecl *Friend = FriendDecl::Create(
1642  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
1643  Friend->setAccess(AS_public);
1644  CurContext->addDecl(Friend);
1645  }
1646 
1647  if (PrevClassTemplate)
1648  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
1649 
1650  if (Invalid) {
1651  NewTemplate->setInvalidDecl();
1652  NewClass->setInvalidDecl();
1653  }
1654 
1655  ActOnDocumentableDecl(NewTemplate);
1656 
1657  if (SkipBody && SkipBody->ShouldSkip)
1658  return SkipBody->Previous;
1659 
1660  return NewTemplate;
1661 }
1662 
1663 namespace {
1664 /// Tree transform to "extract" a transformed type from a class template's
1665 /// constructor to a deduction guide.
1666 class ExtractTypeForDeductionGuide
1667  : public TreeTransform<ExtractTypeForDeductionGuide> {
1668 public:
1670  ExtractTypeForDeductionGuide(Sema &SemaRef) : Base(SemaRef) {}
1671 
1672  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
1673 
1674  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
1675  return TransformType(
1676  TLB,
1678  }
1679 };
1680 
1681 /// Transform to convert portions of a constructor declaration into the
1682 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
1683 struct ConvertConstructorToDeductionGuideTransform {
1684  ConvertConstructorToDeductionGuideTransform(Sema &S,
1685  ClassTemplateDecl *Template)
1686  : SemaRef(S), Template(Template) {}
1687 
1688  Sema &SemaRef;
1689  ClassTemplateDecl *Template;
1690 
1691  DeclContext *DC = Template->getDeclContext();
1692  CXXRecordDecl *Primary = Template->getTemplatedDecl();
1693  DeclarationName DeductionGuideName =
1695 
1696  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
1697 
1698  // Index adjustment to apply to convert depth-1 template parameters into
1699  // depth-0 template parameters.
1700  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
1701 
1702  /// Transform a constructor declaration into a deduction guide.
1703  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
1704  CXXConstructorDecl *CD) {
1706 
1707  LocalInstantiationScope Scope(SemaRef);
1708 
1709  // C++ [over.match.class.deduct]p1:
1710  // -- For each constructor of the class template designated by the
1711  // template-name, a function template with the following properties:
1712 
1713  // -- The template parameters are the template parameters of the class
1714  // template followed by the template parameters (including default
1715  // template arguments) of the constructor, if any.
1716  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
1717  if (FTD) {
1718  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
1719  SmallVector<NamedDecl *, 16> AllParams;
1720  AllParams.reserve(TemplateParams->size() + InnerParams->size());
1721  AllParams.insert(AllParams.begin(),
1722  TemplateParams->begin(), TemplateParams->end());
1723  SubstArgs.reserve(InnerParams->size());
1724 
1725  // Later template parameters could refer to earlier ones, so build up
1726  // a list of substituted template arguments as we go.
1727  for (NamedDecl *Param : *InnerParams) {
1729  Args.addOuterTemplateArguments(SubstArgs);
1730  Args.addOuterRetainedLevel();
1731  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
1732  if (!NewParam)
1733  return nullptr;
1734  AllParams.push_back(NewParam);
1735  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
1736  SemaRef.Context.getInjectedTemplateArg(NewParam)));
1737  }
1738  TemplateParams = TemplateParameterList::Create(
1739  SemaRef.Context, InnerParams->getTemplateLoc(),
1740  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
1741  /*FIXME: RequiresClause*/ nullptr);
1742  }
1743 
1744  // If we built a new template-parameter-list, track that we need to
1745  // substitute references to the old parameters into references to the
1746  // new ones.
1748  if (FTD) {
1749  Args.addOuterTemplateArguments(SubstArgs);
1750  Args.addOuterRetainedLevel();
1751  }
1752 
1755  assert(FPTL && "no prototype for constructor declaration");
1756 
1757  // Transform the type of the function, adjusting the return type and
1758  // replacing references to the old parameters with references to the
1759  // new ones.
1760  TypeLocBuilder TLB;
1762  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args);
1763  if (NewType.isNull())
1764  return nullptr;
1765  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
1766 
1767  return buildDeductionGuide(TemplateParams, CD->isExplicit(), NewTInfo,
1768  CD->getBeginLoc(), CD->getLocation(),
1769  CD->getEndLoc());
1770  }
1771 
1772  /// Build a deduction guide with the specified parameter types.
1773  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
1774  SourceLocation Loc = Template->getLocation();
1775 
1776  // Build the requested type.
1778  EPI.HasTrailingReturn = true;
1779  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
1780  DeductionGuideName, EPI);
1781  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
1782 
1783  FunctionProtoTypeLoc FPTL =
1785 
1786  // Build the parameters, needed during deduction / substitution.
1788  for (auto T : ParamTypes) {
1789  ParmVarDecl *NewParam = ParmVarDecl::Create(
1790  SemaRef.Context, DC, Loc, Loc, nullptr, T,
1791  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
1792  NewParam->setScopeInfo(0, Params.size());
1793  FPTL.setParam(Params.size(), NewParam);
1794  Params.push_back(NewParam);
1795  }
1796 
1797  return buildDeductionGuide(Template->getTemplateParameters(), false, TSI,
1798  Loc, Loc, Loc);
1799  }
1800 
1801 private:
1802  /// Transform a constructor template parameter into a deduction guide template
1803  /// parameter, rebuilding any internal references to earlier parameters and
1804  /// renumbering as we go.
1805  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
1807  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
1808  // TemplateTypeParmDecl's index cannot be changed after creation, so
1809  // substitute it directly.
1810  auto *NewTTP = TemplateTypeParmDecl::Create(
1811  SemaRef.Context, DC, TTP->getBeginLoc(), TTP->getLocation(),
1812  /*Depth*/ 0, Depth1IndexAdjustment + TTP->getIndex(),
1813  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
1814  TTP->isParameterPack());
1815  if (TTP->hasDefaultArgument()) {
1816  TypeSourceInfo *InstantiatedDefaultArg =
1817  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
1818  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
1819  if (InstantiatedDefaultArg)
1820  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
1821  }
1822  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
1823  NewTTP);
1824  return NewTTP;
1825  }
1826 
1827  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
1828  return transformTemplateParameterImpl(TTP, Args);
1829 
1830  return transformTemplateParameterImpl(
1831  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
1832  }
1833  template<typename TemplateParmDecl>
1834  TemplateParmDecl *
1835  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
1837  // Ask the template instantiator to do the heavy lifting for us, then adjust
1838  // the index of the parameter once it's done.
1839  auto *NewParam =
1840  cast_or_null<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
1841  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
1842  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
1843  return NewParam;
1844  }
1845 
1846  QualType transformFunctionProtoType(TypeLocBuilder &TLB,
1850  SmallVector<QualType, 4> ParamTypes;
1851  const FunctionProtoType *T = TL.getTypePtr();
1852 
1853  // -- The types of the function parameters are those of the constructor.
1854  for (auto *OldParam : TL.getParams()) {
1855  ParmVarDecl *NewParam = transformFunctionTypeParam(OldParam, Args);
1856  if (!NewParam)
1857  return QualType();
1858  ParamTypes.push_back(NewParam->getType());
1859  Params.push_back(NewParam);
1860  }
1861 
1862  // -- The return type is the class template specialization designated by
1863  // the template-name and template arguments corresponding to the
1864  // template parameters obtained from the class template.
1865  //
1866  // We use the injected-class-name type of the primary template instead.
1867  // This has the convenient property that it is different from any type that
1868  // the user can write in a deduction-guide (because they cannot enter the
1869  // context of the template), so implicit deduction guides can never collide
1870  // with explicit ones.
1871  QualType ReturnType = DeducedType;
1872  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
1873 
1874  // Resolving a wording defect, we also inherit the variadicness of the
1875  // constructor.
1877  EPI.Variadic = T->isVariadic();
1878  EPI.HasTrailingReturn = true;
1879 
1880  QualType Result = SemaRef.BuildFunctionType(
1881  ReturnType, ParamTypes, TL.getBeginLoc(), DeductionGuideName, EPI);
1882  if (Result.isNull())
1883  return QualType();
1884 
1885  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
1887  NewTL.setLParenLoc(TL.getLParenLoc());
1888  NewTL.setRParenLoc(TL.getRParenLoc());
1890  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
1891  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
1892  NewTL.setParam(I, Params[I]);
1893 
1894  return Result;
1895  }
1896 
1897  ParmVarDecl *
1898  transformFunctionTypeParam(ParmVarDecl *OldParam,
1900  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
1901  TypeSourceInfo *NewDI;
1902  if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
1903  // Expand out the one and only element in each inner pack.
1904  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
1905  NewDI =
1906  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
1907  OldParam->getLocation(), OldParam->getDeclName());
1908  if (!NewDI) return nullptr;
1909  NewDI =
1910  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
1911  PackTL.getTypePtr()->getNumExpansions());
1912  } else
1913  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
1914  OldParam->getDeclName());
1915  if (!NewDI)
1916  return nullptr;
1917 
1918  // Extract the type. This (for instance) replaces references to typedef
1919  // members of the current instantiations with the definitions of those
1920  // typedefs, avoiding triggering instantiation of the deduced type during
1921  // deduction.
1922  NewDI = ExtractTypeForDeductionGuide(SemaRef).transform(NewDI);
1923 
1924  // Resolving a wording defect, we also inherit default arguments from the
1925  // constructor.
1926  ExprResult NewDefArg;
1927  if (OldParam->hasDefaultArg()) {
1928  NewDefArg = SemaRef.SubstExpr(OldParam->getDefaultArg(), Args);
1929  if (NewDefArg.isInvalid())
1930  return nullptr;
1931  }
1932 
1933  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
1934  OldParam->getInnerLocStart(),
1935  OldParam->getLocation(),
1936  OldParam->getIdentifier(),
1937  NewDI->getType(),
1938  NewDI,
1939  OldParam->getStorageClass(),
1940  NewDefArg.get());
1941  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
1942  OldParam->getFunctionScopeIndex());
1943  SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
1944  return NewParam;
1945  }
1946 
1947  NamedDecl *buildDeductionGuide(TemplateParameterList *TemplateParams,
1948  bool Explicit, TypeSourceInfo *TInfo,
1949  SourceLocation LocStart, SourceLocation Loc,
1950  SourceLocation LocEnd) {
1951  DeclarationNameInfo Name(DeductionGuideName, Loc);
1952  ArrayRef<ParmVarDecl *> Params =
1953  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
1954 
1955  // Build the implicit deduction guide template.
1956  auto *Guide =
1957  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, Explicit,
1958  Name, TInfo->getType(), TInfo, LocEnd);
1959  Guide->setImplicit();
1960  Guide->setParams(Params);
1961 
1962  for (auto *Param : Params)
1963  Param->setDeclContext(Guide);
1964 
1965  auto *GuideTemplate = FunctionTemplateDecl::Create(
1966  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
1967  GuideTemplate->setImplicit();
1968  Guide->setDescribedFunctionTemplate(GuideTemplate);
1969 
1970  if (isa<CXXRecordDecl>(DC)) {
1971  Guide->setAccess(AS_public);
1972  GuideTemplate->setAccess(AS_public);
1973  }
1974 
1975  DC->addDecl(GuideTemplate);
1976  return GuideTemplate;
1977  }
1978 };
1979 }
1980 
1982  SourceLocation Loc) {
1983  DeclContext *DC = Template->getDeclContext();
1984  if (DC->isDependentContext())
1985  return;
1986 
1987  ConvertConstructorToDeductionGuideTransform Transform(
1988  *this, cast<ClassTemplateDecl>(Template));
1989  if (!isCompleteType(Loc, Transform.DeducedType))
1990  return;
1991 
1992  // Check whether we've already declared deduction guides for this template.
1993  // FIXME: Consider storing a flag on the template to indicate this.
1994  auto Existing = DC->lookup(Transform.DeductionGuideName);
1995  for (auto *D : Existing)
1996  if (D->isImplicit())
1997  return;
1998 
1999  // In case we were expanding a pack when we attempted to declare deduction
2000  // guides, turn off pack expansion for everything we're about to do.
2001  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
2002  // Create a template instantiation record to track the "instantiation" of
2003  // constructors into deduction guides.
2004  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
2005  // this substitution process actually fail?
2006  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
2007  if (BuildingDeductionGuides.isInvalid())
2008  return;
2009 
2010  // Convert declared constructors into deduction guide templates.
2011  // FIXME: Skip constructors for which deduction must necessarily fail (those
2012  // for which some class template parameter without a default argument never
2013  // appears in a deduced context).
2014  bool AddedAny = false;
2015  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2016  D = D->getUnderlyingDecl();
2017  if (D->isInvalidDecl() || D->isImplicit())
2018  continue;
2019  D = cast<NamedDecl>(D->getCanonicalDecl());
2020 
2021  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2022  auto *CD =
2023  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2024  // Class-scope explicit specializations (MS extension) do not result in
2025  // deduction guides.
2026  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2027  continue;
2028 
2029  Transform.transformConstructor(FTD, CD);
2030  AddedAny = true;
2031  }
2032 
2033  // C++17 [over.match.class.deduct]
2034  // -- If C is not defined or does not declare any constructors, an
2035  // additional function template derived as above from a hypothetical
2036  // constructor C().
2037  if (!AddedAny)
2038  Transform.buildSimpleDeductionGuide(None);
2039 
2040  // -- An additional function template derived as above from a hypothetical
2041  // constructor C(C), called the copy deduction candidate.
2042  cast<CXXDeductionGuideDecl>(
2043  cast<FunctionTemplateDecl>(
2044  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2045  ->getTemplatedDecl())
2046  ->setIsCopyDeductionCandidate();
2047 }
2048 
2049 /// Diagnose the presence of a default template argument on a
2050 /// template parameter, which is ill-formed in certain contexts.
2051 ///
2052 /// \returns true if the default template argument should be dropped.
2055  SourceLocation ParamLoc,
2056  SourceRange DefArgRange) {
2057  switch (TPC) {
2059  case Sema::TPC_VarTemplate:
2061  return false;
2062 
2065  // C++ [temp.param]p9:
2066  // A default template-argument shall not be specified in a
2067  // function template declaration or a function template
2068  // definition [...]
2069  // If a friend function template declaration specifies a default
2070  // template-argument, that declaration shall be a definition and shall be
2071  // the only declaration of the function template in the translation unit.
2072  // (C++98/03 doesn't have this wording; see DR226).
2073  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2074  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2075  : diag::ext_template_parameter_default_in_function_template)
2076  << DefArgRange;
2077  return false;
2078 
2080  // C++0x [temp.param]p9:
2081  // A default template-argument shall not be specified in the
2082  // template-parameter-lists of the definition of a member of a
2083  // class template that appears outside of the member's class.
2084  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2085  << DefArgRange;
2086  return true;
2087 
2090  // C++ [temp.param]p9:
2091  // A default template-argument shall not be specified in a
2092  // friend template declaration.
2093  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2094  << DefArgRange;
2095  return true;
2096 
2097  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2098  // for friend function templates if there is only a single
2099  // declaration (and it is a definition). Strange!
2100  }
2101 
2102  llvm_unreachable("Invalid TemplateParamListContext!");
2103 }
2104 
2105 /// Check for unexpanded parameter packs within the template parameters
2106 /// of a template template parameter, recursively.
2108  TemplateTemplateParmDecl *TTP) {
2109  // A template template parameter which is a parameter pack is also a pack
2110  // expansion.
2111  if (TTP->isParameterPack())
2112  return false;
2113 
2115  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2116  NamedDecl *P = Params->getParam(I);
2117  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2118  if (!NTTP->isParameterPack() &&
2119  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2120  NTTP->getTypeSourceInfo(),
2122  return true;
2123 
2124  continue;
2125  }
2126 
2127  if (TemplateTemplateParmDecl *InnerTTP
2128  = dyn_cast<TemplateTemplateParmDecl>(P))
2129  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2130  return true;
2131  }
2132 
2133  return false;
2134 }
2135 
2136 /// Checks the validity of a template parameter list, possibly
2137 /// considering the template parameter list from a previous
2138 /// declaration.
2139 ///
2140 /// If an "old" template parameter list is provided, it must be
2141 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2142 /// template parameter list.
2143 ///
2144 /// \param NewParams Template parameter list for a new template
2145 /// declaration. This template parameter list will be updated with any
2146 /// default arguments that are carried through from the previous
2147 /// template parameter list.
2148 ///
2149 /// \param OldParams If provided, template parameter list from a
2150 /// previous declaration of the same template. Default template
2151 /// arguments will be merged from the old template parameter list to
2152 /// the new template parameter list.
2153 ///
2154 /// \param TPC Describes the context in which we are checking the given
2155 /// template parameter list.
2156 ///
2157 /// \param SkipBody If we might have already made a prior merged definition
2158 /// of this template visible, the corresponding body-skipping information.
2159 /// Default argument redefinition is not an error when skipping such a body,
2160 /// because (under the ODR) we can assume the default arguments are the same
2161 /// as the prior merged definition.
2162 ///
2163 /// \returns true if an error occurred, false otherwise.
2165  TemplateParameterList *OldParams,
2167  SkipBodyInfo *SkipBody) {
2168  bool Invalid = false;
2169 
2170  // C++ [temp.param]p10:
2171  // The set of default template-arguments available for use with a
2172  // template declaration or definition is obtained by merging the
2173  // default arguments from the definition (if in scope) and all
2174  // declarations in scope in the same way default function
2175  // arguments are (8.3.6).
2176  bool SawDefaultArgument = false;
2177  SourceLocation PreviousDefaultArgLoc;
2178 
2179  // Dummy initialization to avoid warnings.
2180  TemplateParameterList::iterator OldParam = NewParams->end();
2181  if (OldParams)
2182  OldParam = OldParams->begin();
2183 
2184  bool RemoveDefaultArguments = false;
2185  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2186  NewParamEnd = NewParams->end();
2187  NewParam != NewParamEnd; ++NewParam) {
2188  // Variables used to diagnose redundant default arguments
2189  bool RedundantDefaultArg = false;
2190  SourceLocation OldDefaultLoc;
2191  SourceLocation NewDefaultLoc;
2192 
2193  // Variable used to diagnose missing default arguments
2194  bool MissingDefaultArg = false;
2195 
2196  // Variable used to diagnose non-final parameter packs
2197  bool SawParameterPack = false;
2198 
2199  if (TemplateTypeParmDecl *NewTypeParm
2200  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2201  // Check the presence of a default argument here.
2202  if (NewTypeParm->hasDefaultArgument() &&
2204  NewTypeParm->getLocation(),
2205  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2206  .getSourceRange()))
2207  NewTypeParm->removeDefaultArgument();
2208 
2209  // Merge default arguments for template type parameters.
2210  TemplateTypeParmDecl *OldTypeParm
2211  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2212  if (NewTypeParm->isParameterPack()) {
2213  assert(!NewTypeParm->hasDefaultArgument() &&
2214  "Parameter packs can't have a default argument!");
2215  SawParameterPack = true;
2216  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2217  NewTypeParm->hasDefaultArgument() &&
2218  (!SkipBody || !SkipBody->ShouldSkip)) {
2219  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2220  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2221  SawDefaultArgument = true;
2222  RedundantDefaultArg = true;
2223  PreviousDefaultArgLoc = NewDefaultLoc;
2224  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2225  // Merge the default argument from the old declaration to the
2226  // new declaration.
2227  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2228  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2229  } else if (NewTypeParm->hasDefaultArgument()) {
2230  SawDefaultArgument = true;
2231  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2232  } else if (SawDefaultArgument)
2233  MissingDefaultArg = true;
2234  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2235  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2236  // Check for unexpanded parameter packs.
2237  if (!NewNonTypeParm->isParameterPack() &&
2238  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2239  NewNonTypeParm->getTypeSourceInfo(),
2240  UPPC_NonTypeTemplateParameterType)) {
2241  Invalid = true;
2242  continue;
2243  }
2244 
2245  // Check the presence of a default argument here.
2246  if (NewNonTypeParm->hasDefaultArgument() &&
2248  NewNonTypeParm->getLocation(),
2249  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2250  NewNonTypeParm->removeDefaultArgument();
2251  }
2252 
2253  // Merge default arguments for non-type template parameters
2254  NonTypeTemplateParmDecl *OldNonTypeParm
2255  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2256  if (NewNonTypeParm->isParameterPack()) {
2257  assert(!NewNonTypeParm->hasDefaultArgument() &&
2258  "Parameter packs can't have a default argument!");
2259  if (!NewNonTypeParm->isPackExpansion())
2260  SawParameterPack = true;
2261  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2262  NewNonTypeParm->hasDefaultArgument() &&
2263  (!SkipBody || !SkipBody->ShouldSkip)) {
2264  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2265  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2266  SawDefaultArgument = true;
2267  RedundantDefaultArg = true;
2268  PreviousDefaultArgLoc = NewDefaultLoc;
2269  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2270  // Merge the default argument from the old declaration to the
2271  // new declaration.
2272  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2273  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2274  } else if (NewNonTypeParm->hasDefaultArgument()) {
2275  SawDefaultArgument = true;
2276  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2277  } else if (SawDefaultArgument)
2278  MissingDefaultArg = true;
2279  } else {
2280  TemplateTemplateParmDecl *NewTemplateParm
2281  = cast<TemplateTemplateParmDecl>(*NewParam);
2282 
2283  // Check for unexpanded parameter packs, recursively.
2284  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2285  Invalid = true;
2286  continue;
2287  }
2288 
2289  // Check the presence of a default argument here.
2290  if (NewTemplateParm->hasDefaultArgument() &&
2292  NewTemplateParm->getLocation(),
2293  NewTemplateParm->getDefaultArgument().getSourceRange()))
2294  NewTemplateParm->removeDefaultArgument();
2295 
2296  // Merge default arguments for template template parameters
2297  TemplateTemplateParmDecl *OldTemplateParm
2298  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2299  if (NewTemplateParm->isParameterPack()) {
2300  assert(!NewTemplateParm->hasDefaultArgument() &&
2301  "Parameter packs can't have a default argument!");
2302  if (!NewTemplateParm->isPackExpansion())
2303  SawParameterPack = true;
2304  } else if (OldTemplateParm &&
2305  hasVisibleDefaultArgument(OldTemplateParm) &&
2306  NewTemplateParm->hasDefaultArgument() &&
2307  (!SkipBody || !SkipBody->ShouldSkip)) {
2308  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2309  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2310  SawDefaultArgument = true;
2311  RedundantDefaultArg = true;
2312  PreviousDefaultArgLoc = NewDefaultLoc;
2313  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2314  // Merge the default argument from the old declaration to the
2315  // new declaration.
2316  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2317  PreviousDefaultArgLoc
2318  = OldTemplateParm->getDefaultArgument().getLocation();
2319  } else if (NewTemplateParm->hasDefaultArgument()) {
2320  SawDefaultArgument = true;
2321  PreviousDefaultArgLoc
2322  = NewTemplateParm->getDefaultArgument().getLocation();
2323  } else if (SawDefaultArgument)
2324  MissingDefaultArg = true;
2325  }
2326 
2327  // C++11 [temp.param]p11:
2328  // If a template parameter of a primary class template or alias template
2329  // is a template parameter pack, it shall be the last template parameter.
2330  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2331  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2332  TPC == TPC_TypeAliasTemplate)) {
2333  Diag((*NewParam)->getLocation(),
2334  diag::err_template_param_pack_must_be_last_template_parameter);
2335  Invalid = true;
2336  }
2337 
2338  if (RedundantDefaultArg) {
2339  // C++ [temp.param]p12:
2340  // A template-parameter shall not be given default arguments
2341  // by two different declarations in the same scope.
2342  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2343  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2344  Invalid = true;
2345  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2346  // C++ [temp.param]p11:
2347  // If a template-parameter of a class template has a default
2348  // template-argument, each subsequent template-parameter shall either
2349  // have a default template-argument supplied or be a template parameter
2350  // pack.
2351  Diag((*NewParam)->getLocation(),
2352  diag::err_template_param_default_arg_missing);
2353  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2354  Invalid = true;
2355  RemoveDefaultArguments = true;
2356  }
2357 
2358  // If we have an old template parameter list that we're merging
2359  // in, move on to the next parameter.
2360  if (OldParams)
2361  ++OldParam;
2362  }
2363 
2364  // We were missing some default arguments at the end of the list, so remove
2365  // all of the default arguments.
2366  if (RemoveDefaultArguments) {
2367  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2368  NewParamEnd = NewParams->end();
2369  NewParam != NewParamEnd; ++NewParam) {
2370  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2371  TTP->removeDefaultArgument();
2372  else if (NonTypeTemplateParmDecl *NTTP
2373  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2374  NTTP->removeDefaultArgument();
2375  else
2376  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2377  }
2378  }
2379 
2380  return Invalid;
2381 }
2382 
2383 namespace {
2384 
2385 /// A class which looks for a use of a certain level of template
2386 /// parameter.
2387 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2389 
2390  unsigned Depth;
2391 
2392  // Whether we're looking for a use of a template parameter that makes the
2393  // overall construct type-dependent / a dependent type. This is strictly
2394  // best-effort for now; we may fail to match at all for a dependent type
2395  // in some cases if this is set.
2396  bool IgnoreNonTypeDependent;
2397 
2398  bool Match;
2399  SourceLocation MatchLoc;
2400 
2401  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2402  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2403  Match(false) {}
2404 
2405  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2406  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2407  NamedDecl *ND = Params->getParam(0);
2408  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2409  Depth = PD->getDepth();
2410  } else if (NonTypeTemplateParmDecl *PD =
2411  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2412  Depth = PD->getDepth();
2413  } else {
2414  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2415  }
2416  }
2417 
2418  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2419  if (ParmDepth >= Depth) {
2420  Match = true;
2421  MatchLoc = Loc;
2422  return true;
2423  }
2424  return false;
2425  }
2426 
2427  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2428  // Prune out non-type-dependent expressions if requested. This can
2429  // sometimes result in us failing to find a template parameter reference
2430  // (if a value-dependent expression creates a dependent type), but this
2431  // mode is best-effort only.
2432  if (auto *E = dyn_cast_or_null<Expr>(S))
2433  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2434  return true;
2435  return super::TraverseStmt(S, Q);
2436  }
2437 
2438  bool TraverseTypeLoc(TypeLoc TL) {
2439  if (IgnoreNonTypeDependent && !TL.isNull() &&
2440  !TL.getType()->isDependentType())
2441  return true;
2442  return super::TraverseTypeLoc(TL);
2443  }
2444 
2445  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2446  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2447  }
2448 
2449  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2450  // For a best-effort search, keep looking until we find a location.
2451  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2452  }
2453 
2454  bool TraverseTemplateName(TemplateName N) {
2455  if (TemplateTemplateParmDecl *PD =
2456  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2457  if (Matches(PD->getDepth()))
2458  return false;
2459  return super::TraverseTemplateName(N);
2460  }
2461 
2462  bool VisitDeclRefExpr(DeclRefExpr *E) {
2463  if (NonTypeTemplateParmDecl *PD =
2464  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2465  if (Matches(PD->getDepth(), E->getExprLoc()))
2466  return false;
2467  return super::VisitDeclRefExpr(E);
2468  }
2469 
2470  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2471  return TraverseType(T->getReplacementType());
2472  }
2473 
2474  bool
2475  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2476  return TraverseTemplateArgument(T->getArgumentPack());
2477  }
2478 
2479  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2480  return TraverseType(T->getInjectedSpecializationType());
2481  }
2482 };
2483 } // end anonymous namespace
2484 
2485 /// Determines whether a given type depends on the given parameter
2486 /// list.
2487 static bool
2489  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2490  Checker.TraverseType(T);
2491  return Checker.Match;
2492 }
2493 
2494 // Find the source range corresponding to the named type in the given
2495 // nested-name-specifier, if any.
2497  QualType T,
2498  const CXXScopeSpec &SS) {
2500  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2501  if (const Type *CurType = NNS->getAsType()) {
2502  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2503  return NNSLoc.getTypeLoc().getSourceRange();
2504  } else
2505  break;
2506 
2507  NNSLoc = NNSLoc.getPrefix();
2508  }
2509 
2510  return SourceRange();
2511 }
2512 
2513 /// Match the given template parameter lists to the given scope
2514 /// specifier, returning the template parameter list that applies to the
2515 /// name.
2516 ///
2517 /// \param DeclStartLoc the start of the declaration that has a scope
2518 /// specifier or a template parameter list.
2519 ///
2520 /// \param DeclLoc The location of the declaration itself.
2521 ///
2522 /// \param SS the scope specifier that will be matched to the given template
2523 /// parameter lists. This scope specifier precedes a qualified name that is
2524 /// being declared.
2525 ///
2526 /// \param TemplateId The template-id following the scope specifier, if there
2527 /// is one. Used to check for a missing 'template<>'.
2528 ///
2529 /// \param ParamLists the template parameter lists, from the outermost to the
2530 /// innermost template parameter lists.
2531 ///
2532 /// \param IsFriend Whether to apply the slightly different rules for
2533 /// matching template parameters to scope specifiers in friend
2534 /// declarations.
2535 ///
2536 /// \param IsMemberSpecialization will be set true if the scope specifier
2537 /// denotes a fully-specialized type, and therefore this is a declaration of
2538 /// a member specialization.
2539 ///
2540 /// \returns the template parameter list, if any, that corresponds to the
2541 /// name that is preceded by the scope specifier @p SS. This template
2542 /// parameter list may have template parameters (if we're declaring a
2543 /// template) or may have no template parameters (if we're declaring a
2544 /// template specialization), or may be NULL (if what we're declaring isn't
2545 /// itself a template).
2547  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
2548  TemplateIdAnnotation *TemplateId,
2549  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
2550  bool &IsMemberSpecialization, bool &Invalid) {
2551  IsMemberSpecialization = false;
2552  Invalid = false;
2553 
2554  // The sequence of nested types to which we will match up the template
2555  // parameter lists. We first build this list by starting with the type named
2556  // by the nested-name-specifier and walking out until we run out of types.
2557  SmallVector<QualType, 4> NestedTypes;
2558  QualType T;
2559  if (SS.getScopeRep()) {
2560  if (CXXRecordDecl *Record
2561  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
2562  T = Context.getTypeDeclType(Record);
2563  else
2564  T = QualType(SS.getScopeRep()->getAsType(), 0);
2565  }
2566 
2567  // If we found an explicit specialization that prevents us from needing
2568  // 'template<>' headers, this will be set to the location of that
2569  // explicit specialization.
2570  SourceLocation ExplicitSpecLoc;
2571 
2572  while (!T.isNull()) {
2573  NestedTypes.push_back(T);
2574 
2575  // Retrieve the parent of a record type.
2576  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2577  // If this type is an explicit specialization, we're done.
2579  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2580  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
2581  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
2582  ExplicitSpecLoc = Spec->getLocation();
2583  break;
2584  }
2585  } else if (Record->getTemplateSpecializationKind()
2587  ExplicitSpecLoc = Record->getLocation();
2588  break;
2589  }
2590 
2591  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
2592  T = Context.getTypeDeclType(Parent);
2593  else
2594  T = QualType();
2595  continue;
2596  }
2597 
2598  if (const TemplateSpecializationType *TST
2600  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2601  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
2602  T = Context.getTypeDeclType(Parent);
2603  else
2604  T = QualType();
2605  continue;
2606  }
2607  }
2608 
2609  // Look one step prior in a dependent template specialization type.
2610  if (const DependentTemplateSpecializationType *DependentTST
2612  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
2613  T = QualType(NNS->getAsType(), 0);
2614  else
2615  T = QualType();
2616  continue;
2617  }
2618 
2619  // Look one step prior in a dependent name type.
2620  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
2621  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
2622  T = QualType(NNS->getAsType(), 0);
2623  else
2624  T = QualType();
2625  continue;
2626  }
2627 
2628  // Retrieve the parent of an enumeration type.
2629  if (const EnumType *EnumT = T->getAs<EnumType>()) {
2630  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
2631  // check here.
2632  EnumDecl *Enum = EnumT->getDecl();
2633 
2634  // Get to the parent type.
2635  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
2636  T = Context.getTypeDeclType(Parent);
2637  else
2638  T = QualType();
2639  continue;
2640  }
2641 
2642  T = QualType();
2643  }
2644  // Reverse the nested types list, since we want to traverse from the outermost
2645  // to the innermost while checking template-parameter-lists.
2646  std::reverse(NestedTypes.begin(), NestedTypes.end());
2647 
2648  // C++0x [temp.expl.spec]p17:
2649  // A member or a member template may be nested within many
2650  // enclosing class templates. In an explicit specialization for
2651  // such a member, the member declaration shall be preceded by a
2652  // template<> for each enclosing class template that is
2653  // explicitly specialized.
2654  bool SawNonEmptyTemplateParameterList = false;
2655 
2656  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
2657  if (SawNonEmptyTemplateParameterList) {
2658  Diag(DeclLoc, diag::err_specialize_member_of_template)
2659  << !Recovery << Range;
2660  Invalid = true;
2661  IsMemberSpecialization = false;
2662  return true;
2663  }
2664 
2665  return false;
2666  };
2667 
2668  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
2669  // Check that we can have an explicit specialization here.
2670  if (CheckExplicitSpecialization(Range, true))
2671  return true;
2672 
2673  // We don't have a template header, but we should.
2674  SourceLocation ExpectedTemplateLoc;
2675  if (!ParamLists.empty())
2676  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
2677  else
2678  ExpectedTemplateLoc = DeclStartLoc;
2679 
2680  Diag(DeclLoc, diag::err_template_spec_needs_header)
2681  << Range
2682  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
2683  return false;
2684  };
2685 
2686  unsigned ParamIdx = 0;
2687  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
2688  ++TypeIdx) {
2689  T = NestedTypes[TypeIdx];
2690 
2691  // Whether we expect a 'template<>' header.
2692  bool NeedEmptyTemplateHeader = false;
2693 
2694  // Whether we expect a template header with parameters.
2695  bool NeedNonemptyTemplateHeader = false;
2696 
2697  // For a dependent type, the set of template parameters that we
2698  // expect to see.
2699  TemplateParameterList *ExpectedTemplateParams = nullptr;
2700 
2701  // C++0x [temp.expl.spec]p15:
2702  // A member or a member template may be nested within many enclosing
2703  // class templates. In an explicit specialization for such a member, the
2704  // member declaration shall be preceded by a template<> for each
2705  // enclosing class template that is explicitly specialized.
2706  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2708  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
2709  ExpectedTemplateParams = Partial->getTemplateParameters();
2710  NeedNonemptyTemplateHeader = true;
2711  } else if (Record->isDependentType()) {
2712  if (Record->getDescribedClassTemplate()) {
2713  ExpectedTemplateParams = Record->getDescribedClassTemplate()
2714  ->getTemplateParameters();
2715  NeedNonemptyTemplateHeader = true;
2716  }
2717  } else if (ClassTemplateSpecializationDecl *Spec
2718  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2719  // C++0x [temp.expl.spec]p4:
2720  // Members of an explicitly specialized class template are defined
2721  // in the same manner as members of normal classes, and not using
2722  // the template<> syntax.
2723  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
2724  NeedEmptyTemplateHeader = true;
2725  else
2726  continue;
2727  } else if (Record->getTemplateSpecializationKind()) {
2728  if (Record->getTemplateSpecializationKind()
2730  TypeIdx == NumTypes - 1)
2731  IsMemberSpecialization = true;
2732 
2733  continue;
2734  }
2735  } else if (const TemplateSpecializationType *TST
2737  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2738  ExpectedTemplateParams = Template->getTemplateParameters();
2739  NeedNonemptyTemplateHeader = true;
2740  }
2741  } else if (T->getAs<DependentTemplateSpecializationType>()) {
2742  // FIXME: We actually could/should check the template arguments here
2743  // against the corresponding template parameter list.
2744  NeedNonemptyTemplateHeader = false;
2745  }
2746 
2747  // C++ [temp.expl.spec]p16:
2748  // In an explicit specialization declaration for a member of a class
2749  // template or a member template that ap- pears in namespace scope, the
2750  // member template and some of its enclosing class templates may remain
2751  // unspecialized, except that the declaration shall not explicitly
2752  // specialize a class member template if its en- closing class templates
2753  // are not explicitly specialized as well.
2754  if (ParamIdx < ParamLists.size()) {
2755  if (ParamLists[ParamIdx]->size() == 0) {
2756  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2757  false))
2758  return nullptr;
2759  } else
2760  SawNonEmptyTemplateParameterList = true;
2761  }
2762 
2763  if (NeedEmptyTemplateHeader) {
2764  // If we're on the last of the types, and we need a 'template<>' header
2765  // here, then it's a member specialization.
2766  if (TypeIdx == NumTypes - 1)
2767  IsMemberSpecialization = true;
2768 
2769  if (ParamIdx < ParamLists.size()) {
2770  if (ParamLists[ParamIdx]->size() > 0) {
2771  // The header has template parameters when it shouldn't. Complain.
2772  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2773  diag::err_template_param_list_matches_nontemplate)
2774  << T
2775  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
2776  ParamLists[ParamIdx]->getRAngleLoc())
2777  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2778  Invalid = true;
2779  return nullptr;
2780  }
2781 
2782  // Consume this template header.
2783  ++ParamIdx;
2784  continue;
2785  }
2786 
2787  if (!IsFriend)
2788  if (DiagnoseMissingExplicitSpecialization(
2789  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
2790  return nullptr;
2791 
2792  continue;
2793  }
2794 
2795  if (NeedNonemptyTemplateHeader) {
2796  // In friend declarations we can have template-ids which don't
2797  // depend on the corresponding template parameter lists. But
2798  // assume that empty parameter lists are supposed to match this
2799  // template-id.
2800  if (IsFriend && T->isDependentType()) {
2801  if (ParamIdx < ParamLists.size() &&
2802  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
2803  ExpectedTemplateParams = nullptr;
2804  else
2805  continue;
2806  }
2807 
2808  if (ParamIdx < ParamLists.size()) {
2809  // Check the template parameter list, if we can.
2810  if (ExpectedTemplateParams &&
2811  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
2812  ExpectedTemplateParams,
2813  true, TPL_TemplateMatch))
2814  Invalid = true;
2815 
2816  if (!Invalid &&
2817  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
2818  TPC_ClassTemplateMember))
2819  Invalid = true;
2820 
2821  ++ParamIdx;
2822  continue;
2823  }
2824 
2825  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
2826  << T
2827  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2828  Invalid = true;
2829  continue;
2830  }
2831  }
2832 
2833  // If there were at least as many template-ids as there were template
2834  // parameter lists, then there are no template parameter lists remaining for
2835  // the declaration itself.
2836  if (ParamIdx >= ParamLists.size()) {
2837  if (TemplateId && !IsFriend) {
2838  // We don't have a template header for the declaration itself, but we
2839  // should.
2840  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
2841  TemplateId->RAngleLoc));
2842 
2843  // Fabricate an empty template parameter list for the invented header.
2845  SourceLocation(), None,
2846  SourceLocation(), nullptr);
2847  }
2848 
2849  return nullptr;
2850  }
2851 
2852  // If there were too many template parameter lists, complain about that now.
2853  if (ParamIdx < ParamLists.size() - 1) {
2854  bool HasAnyExplicitSpecHeader = false;
2855  bool AllExplicitSpecHeaders = true;
2856  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
2857  if (ParamLists[I]->size() == 0)
2858  HasAnyExplicitSpecHeader = true;
2859  else
2860  AllExplicitSpecHeaders = false;
2861  }
2862 
2863  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2864  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
2865  : diag::err_template_spec_extra_headers)
2866  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
2867  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
2868 
2869  // If there was a specialization somewhere, such that 'template<>' is
2870  // not required, and there were any 'template<>' headers, note where the
2871  // specialization occurred.
2872  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
2873  Diag(ExplicitSpecLoc,
2874  diag::note_explicit_template_spec_does_not_need_header)
2875  << NestedTypes.back();
2876 
2877  // We have a template parameter list with no corresponding scope, which
2878  // means that the resulting template declaration can't be instantiated
2879  // properly (we'll end up with dependent nodes when we shouldn't).
2880  if (!AllExplicitSpecHeaders)
2881  Invalid = true;
2882  }
2883 
2884  // C++ [temp.expl.spec]p16:
2885  // In an explicit specialization declaration for a member of a class
2886  // template or a member template that ap- pears in namespace scope, the
2887  // member template and some of its enclosing class templates may remain
2888  // unspecialized, except that the declaration shall not explicitly
2889  // specialize a class member template if its en- closing class templates
2890  // are not explicitly specialized as well.
2891  if (ParamLists.back()->size() == 0 &&
2892  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2893  false))
2894  return nullptr;
2895 
2896  // Return the last template parameter list, which corresponds to the
2897  // entity being declared.
2898  return ParamLists.back();
2899 }
2900 
2902  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
2903  Diag(Template->getLocation(), diag::note_template_declared_here)
2904  << (isa<FunctionTemplateDecl>(Template)
2905  ? 0
2906  : isa<ClassTemplateDecl>(Template)
2907  ? 1
2908  : isa<VarTemplateDecl>(Template)
2909  ? 2
2910  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
2911  << Template->getDeclName();
2912  return;
2913  }
2914 
2916  for (OverloadedTemplateStorage::iterator I = OST->begin(),
2917  IEnd = OST->end();
2918  I != IEnd; ++I)
2919  Diag((*I)->getLocation(), diag::note_template_declared_here)
2920  << 0 << (*I)->getDeclName();
2921 
2922  return;
2923  }
2924 }
2925 
2926 static QualType
2928  const SmallVectorImpl<TemplateArgument> &Converted,
2929  SourceLocation TemplateLoc,
2930  TemplateArgumentListInfo &TemplateArgs) {
2931  ASTContext &Context = SemaRef.getASTContext();
2932  switch (BTD->getBuiltinTemplateKind()) {
2933  case BTK__make_integer_seq: {
2934  // Specializations of __make_integer_seq<S, T, N> are treated like
2935  // S<T, 0, ..., N-1>.
2936 
2937  // C++14 [inteseq.intseq]p1:
2938  // T shall be an integer type.
2939  if (!Converted[1].getAsType()->isIntegralType(Context)) {
2940  SemaRef.Diag(TemplateArgs[1].getLocation(),
2941  diag::err_integer_sequence_integral_element_type);
2942  return QualType();
2943  }
2944 
2945  // C++14 [inteseq.make]p1:
2946  // If N is negative the program is ill-formed.
2947  TemplateArgument NumArgsArg = Converted[2];
2948  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
2949  if (NumArgs < 0) {
2950  SemaRef.Diag(TemplateArgs[2].getLocation(),
2951  diag::err_integer_sequence_negative_length);
2952  return QualType();
2953  }
2954 
2955  QualType ArgTy = NumArgsArg.getIntegralType();
2956  TemplateArgumentListInfo SyntheticTemplateArgs;
2957  // The type argument gets reused as the first template argument in the
2958  // synthetic template argument list.
2959  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
2960  // Expand N into 0 ... N-1.
2961  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
2962  I < NumArgs; ++I) {
2963  TemplateArgument TA(Context, I, ArgTy);
2964  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
2965  TA, ArgTy, TemplateArgs[2].getLocation()));
2966  }
2967  // The first template argument will be reused as the template decl that
2968  // our synthetic template arguments will be applied to.
2969  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
2970  TemplateLoc, SyntheticTemplateArgs);
2971  }
2972 
2974  // Specializations of
2975  // __type_pack_element<Index, T_1, ..., T_N>
2976  // are treated like T_Index.
2977  assert(Converted.size() == 2 &&
2978  "__type_pack_element should be given an index and a parameter pack");
2979 
2980  // If the Index is out of bounds, the program is ill-formed.
2981  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
2982  llvm::APSInt Index = IndexArg.getAsIntegral();
2983  assert(Index >= 0 && "the index used with __type_pack_element should be of "
2984  "type std::size_t, and hence be non-negative");
2985  if (Index >= Ts.pack_size()) {
2986  SemaRef.Diag(TemplateArgs[0].getLocation(),
2987  diag::err_type_pack_element_out_of_bounds);
2988  return QualType();
2989  }
2990 
2991  // We simply return the type at index `Index`.
2992  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
2993  return Nth->getAsType();
2994  }
2995  llvm_unreachable("unexpected BuiltinTemplateDecl!");
2996 }
2997 
2998 /// Determine whether this alias template is "enable_if_t".
2999 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3000  return AliasTemplate->getName().equals("enable_if_t");
3001 }
3002 
3003 /// Collect all of the separable terms in the given condition, which
3004 /// might be a conjunction.
3005 ///
3006 /// FIXME: The right answer is to convert the logical expression into
3007 /// disjunctive normal form, so we can find the first failed term
3008 /// within each possible clause.
3009 static void collectConjunctionTerms(Expr *Clause,
3010  SmallVectorImpl<Expr *> &Terms) {
3011  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3012  if (BinOp->getOpcode() == BO_LAnd) {
3013  collectConjunctionTerms(BinOp->getLHS(), Terms);
3014  collectConjunctionTerms(BinOp->getRHS(), Terms);
3015  }
3016 
3017  return;
3018  }
3019 
3020  Terms.push_back(Clause);
3021 }
3022 
3023 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3024 // a left-hand side that is value-dependent but never true. Identify
3025 // the idiom and ignore that term.
3027  // Top-level '||'.
3028  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3029  if (!BinOp) return Cond;
3030 
3031  if (BinOp->getOpcode() != BO_LOr) return Cond;
3032 
3033  // With an inner '==' that has a literal on the right-hand side.
3034  Expr *LHS = BinOp->getLHS();
3035  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3036  if (!InnerBinOp) return Cond;
3037 
3038  if (InnerBinOp->getOpcode() != BO_EQ ||
3039  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3040  return Cond;
3041 
3042  // If the inner binary operation came from a macro expansion named
3043  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3044  // of the '||', which is the real, user-provided condition.
3045  SourceLocation Loc = InnerBinOp->getExprLoc();
3046  if (!Loc.isMacroID()) return Cond;
3047 
3048  StringRef MacroName = PP.getImmediateMacroName(Loc);
3049  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3050  return BinOp->getRHS();
3051 
3052  return Cond;
3053 }
3054 
3055 // Print a diagnostic for the failing static_assert expression. Defaults to
3056 // pretty-printing the expression.
3057 static void prettyPrintFailedBooleanCondition(llvm::raw_string_ostream &OS,
3058  const Expr *FailedCond,
3059  const PrintingPolicy &Policy) {
3060  const auto *DR = dyn_cast<DeclRefExpr>(FailedCond);
3061  if (DR && DR->getQualifier()) {
3062  // If this is a qualified name, expand the template arguments in nested
3063  // qualifiers.
3064  DR->getQualifier()->print(OS, Policy, true);
3065  // Then print the decl itself.
3066  const ValueDecl *VD = DR->getDecl();
3067  OS << VD->getName();
3068  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3069  // This is a template variable, print the expanded template arguments.
3070  printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
3071  }
3072  return;
3073  }
3074  FailedCond->printPretty(OS, nullptr, Policy);
3075 }
3076 
3077 std::pair<Expr *, std::string>
3078 Sema::findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond) {
3079  Cond = lookThroughRangesV3Condition(PP, Cond);
3080 
3081  // Separate out all of the terms in a conjunction.
3082  SmallVector<Expr *, 4> Terms;
3083  collectConjunctionTerms(Cond, Terms);
3084 
3085  // Determine which term failed.
3086  Expr *FailedCond = nullptr;
3087  for (Expr *Term : Terms) {
3088  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3089 
3090  // Literals are uninteresting.
3091  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3092  isa<IntegerLiteral>(TermAsWritten))
3093  continue;
3094 
3095  // The initialization of the parameter from the argument is
3096  // a constant-evaluated context.
3097  EnterExpressionEvaluationContext ConstantEvaluated(
3099 
3100  bool Succeeded;
3101  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3102  !Succeeded) {
3103  FailedCond = TermAsWritten;
3104  break;
3105  }
3106  }
3107 
3108  if (!FailedCond) {
3109  if (!AllowTopLevelCond)
3110  return { nullptr, "" };
3111 
3112  FailedCond = Cond->IgnoreParenImpCasts();
3113  }
3114 
3115  std::string Description;
3116  {
3117  llvm::raw_string_ostream Out(Description);
3118  prettyPrintFailedBooleanCondition(Out, FailedCond, getPrintingPolicy());
3119  }
3120  return { FailedCond, Description };
3121 }
3122 
3124  SourceLocation TemplateLoc,
3125  TemplateArgumentListInfo &TemplateArgs) {
3128  if (DTN && DTN->isIdentifier())
3129  // When building a template-id where the template-name is dependent,
3130  // assume the template is a type template. Either our assumption is
3131  // correct, or the code is ill-formed and will be diagnosed when the
3132  // dependent name is substituted.
3134  DTN->getQualifier(),
3135  DTN->getIdentifier(),
3136  TemplateArgs);
3137 
3138  TemplateDecl *Template = Name.getAsTemplateDecl();
3139  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3140  isa<VarTemplateDecl>(Template)) {
3141  // We might have a substituted template template parameter pack. If so,
3142  // build a template specialization type for it.
3144  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3145 
3146  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3147  << Name;
3148  NoteAllFoundTemplates(Name);
3149  return QualType();
3150  }
3151 
3152  // Check that the template argument list is well-formed for this
3153  // template.
3155  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3156  false, Converted))
3157  return QualType();
3158 
3159  QualType CanonType;
3160 
3161  bool InstantiationDependent = false;
3162  if (TypeAliasTemplateDecl *AliasTemplate =
3163  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3164  // Find the canonical type for this type alias template specialization.
3165  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3166  if (Pattern->isInvalidDecl())
3167  return QualType();
3168 
3170  Converted);
3171 
3172  // Only substitute for the innermost template argument list.
3173  MultiLevelTemplateArgumentList TemplateArgLists;
3174  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3175  unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
3176  for (unsigned I = 0; I < Depth; ++I)
3177  TemplateArgLists.addOuterTemplateArguments(None);
3178 
3180  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3181  if (Inst.isInvalid())
3182  return QualType();
3183 
3184  CanonType = SubstType(Pattern->getUnderlyingType(),
3185  TemplateArgLists, AliasTemplate->getLocation(),
3186  AliasTemplate->getDeclName());
3187  if (CanonType.isNull()) {
3188  // If this was enable_if and we failed to find the nested type
3189  // within enable_if in a SFINAE context, dig out the specific
3190  // enable_if condition that failed and present that instead.
3191  if (isEnableIfAliasTemplate(AliasTemplate)) {
3192  if (auto DeductionInfo = isSFINAEContext()) {
3193  if (*DeductionInfo &&
3194  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3195  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3196  diag::err_typename_nested_not_found_enable_if &&
3197  TemplateArgs[0].getArgument().getKind()
3199  Expr *FailedCond;
3200  std::string FailedDescription;
3201  std::tie(FailedCond, FailedDescription) =
3202  findFailedBooleanCondition(
3203  TemplateArgs[0].getSourceExpression(),
3204  /*AllowTopLevelCond=*/true);
3205 
3206  // Remove the old SFINAE diagnostic.
3207  PartialDiagnosticAt OldDiag =
3209  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3210 
3211  // Add a new SFINAE diagnostic specifying which condition
3212  // failed.
3213  (*DeductionInfo)->addSFINAEDiagnostic(
3214  OldDiag.first,
3215  PDiag(diag::err_typename_nested_not_found_requirement)
3216  << FailedDescription
3217  << FailedCond->getSourceRange());
3218  }
3219  }
3220  }
3221 
3222  return QualType();
3223  }
3224  } else if (Name.isDependent() ||
3226  TemplateArgs, InstantiationDependent)) {
3227  // This class template specialization is a dependent
3228  // type. Therefore, its canonical type is another class template
3229  // specialization type that contains all of the converted
3230  // arguments in canonical form. This ensures that, e.g., A<T> and
3231  // A<T, T> have identical types when A is declared as:
3232  //
3233  // template<typename T, typename U = T> struct A;
3234  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3235 
3236  // This might work out to be a current instantiation, in which
3237  // case the canonical type needs to be the InjectedClassNameType.
3238  //
3239  // TODO: in theory this could be a simple hashtable lookup; most
3240  // changes to CurContext don't change the set of current
3241  // instantiations.
3242  if (isa<ClassTemplateDecl>(Template)) {
3243  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3244  // If we get out to a namespace, we're done.
3245  if (Ctx->isFileContext()) break;
3246 
3247  // If this isn't a record, keep looking.
3248  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3249  if (!Record) continue;
3250 
3251  // Look for one of the two cases with InjectedClassNameTypes
3252  // and check whether it's the same template.
3253  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3254  !Record->getDescribedClassTemplate())
3255  continue;
3256 
3257  // Fetch the injected class name type and check whether its
3258  // injected type is equal to the type we just built.
3259  QualType ICNT = Context.getTypeDeclType(Record);
3260  QualType Injected = cast<InjectedClassNameType>(ICNT)
3261  ->getInjectedSpecializationType();
3262 
3263  if (CanonType != Injected->getCanonicalTypeInternal())
3264  continue;
3265 
3266  // If so, the canonical type of this TST is the injected
3267  // class name type of the record we just found.
3268  assert(ICNT.isCanonical());
3269  CanonType = ICNT;
3270  break;
3271  }
3272  }
3273  } else if (ClassTemplateDecl *ClassTemplate
3274  = dyn_cast<ClassTemplateDecl>(Template)) {
3275  // Find the class template specialization declaration that
3276  // corresponds to these arguments.
3277  void *InsertPos = nullptr;
3279  = ClassTemplate->findSpecialization(Converted, InsertPos);
3280  if (!Decl) {
3281  // This is the first time we have referenced this class template
3282  // specialization. Create the canonical declaration and add it to
3283  // the set of specializations.
3285  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3286  ClassTemplate->getDeclContext(),
3287  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3288  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3289  ClassTemplate->AddSpecialization(Decl, InsertPos);
3290  if (ClassTemplate->isOutOfLine())
3291  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3292  }
3293 
3294  if (Decl->getSpecializationKind() == TSK_Undeclared) {
3295  MultiLevelTemplateArgumentList TemplateArgLists;
3296  TemplateArgLists.addOuterTemplateArguments(Converted);
3297  InstantiateAttrsForDecl(TemplateArgLists, ClassTemplate->getTemplatedDecl(),
3298  Decl);
3299  }
3300 
3301  // Diagnose uses of this specialization.
3302  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3303 
3304  CanonType = Context.getTypeDeclType(Decl);
3305  assert(isa<RecordType>(CanonType) &&
3306  "type of non-dependent specialization is not a RecordType");
3307  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3308  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3309  TemplateArgs);
3310  }
3311 
3312  // Build the fully-sugared type for this class template
3313  // specialization, which refers back to the class template
3314  // specialization we created or found.
3315  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3316 }
3317 
3318 TypeResult
3320  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3321  SourceLocation TemplateIILoc,
3322  SourceLocation LAngleLoc,
3323  ASTTemplateArgsPtr TemplateArgsIn,
3324  SourceLocation RAngleLoc,
3325  bool IsCtorOrDtorName, bool IsClassName) {
3326  if (SS.isInvalid())
3327  return true;
3328 
3329  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3330  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3331 
3332  // C++ [temp.res]p3:
3333  // A qualified-id that refers to a type and in which the
3334  // nested-name-specifier depends on a template-parameter (14.6.2)
3335  // shall be prefixed by the keyword typename to indicate that the
3336  // qualified-id denotes a type, forming an
3337  // elaborated-type-specifier (7.1.5.3).
3338  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3339  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3340  << SS.getScopeRep() << TemplateII->getName();
3341  // Recover as if 'typename' were specified.
3342  // FIXME: This is not quite correct recovery as we don't transform SS
3343  // into the corresponding dependent form (and we don't diagnose missing
3344  // 'template' keywords within SS as a result).
3345  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3346  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3347  TemplateArgsIn, RAngleLoc);
3348  }
3349 
3350  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3351  // it's not actually allowed to be used as a type in most cases. Because
3352  // we annotate it before we know whether it's valid, we have to check for
3353  // this case here.
3354  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3355  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3356  Diag(TemplateIILoc,
3357  TemplateKWLoc.isInvalid()
3358  ? diag::err_out_of_line_qualified_id_type_names_constructor
3359  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3360  << TemplateII << 0 /*injected-class-name used as template name*/
3361  << 1 /*if any keyword was present, it was 'template'*/;
3362  }
3363  }
3364 
3365  TemplateName Template = TemplateD.get();
3366 
3367  // Translate the parser's template argument list in our AST format.
3368  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3369  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3370 
3371  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3372  QualType T
3374  DTN->getQualifier(),
3375  DTN->getIdentifier(),
3376  TemplateArgs);
3377  // Build type-source information.
3378  TypeLocBuilder TLB;
3382  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3383  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3384  SpecTL.setTemplateNameLoc(TemplateIILoc);
3385  SpecTL.setLAngleLoc(LAngleLoc);
3386  SpecTL.setRAngleLoc(RAngleLoc);
3387  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3388  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3389  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3390  }
3391 
3392  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3393  if (Result.isNull())
3394  return true;
3395 
3396  // Build type-source information.
3397  TypeLocBuilder TLB;
3399  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3400  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3401  SpecTL.setTemplateNameLoc(TemplateIILoc);
3402  SpecTL.setLAngleLoc(LAngleLoc);
3403  SpecTL.setRAngleLoc(RAngleLoc);
3404  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3405  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3406 
3407  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3408  // constructor or destructor name (in such a case, the scope specifier
3409  // will be attached to the enclosing Decl or Expr node).
3410  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3411  // Create an elaborated-type-specifier containing the nested-name-specifier.
3412  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3413  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3415  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3416  }
3417 
3418  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3419 }
3420 
3422  TypeSpecifierType TagSpec,
3423  SourceLocation TagLoc,
3424  CXXScopeSpec &SS,
3425  SourceLocation TemplateKWLoc,
3426  TemplateTy TemplateD,
3427  SourceLocation TemplateLoc,
3428  SourceLocation LAngleLoc,
3429  ASTTemplateArgsPtr TemplateArgsIn,
3430  SourceLocation RAngleLoc) {
3431  TemplateName Template = TemplateD.get();
3432 
3433  // Translate the parser's template argument list in our AST format.
3434  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3435  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3436 
3437  // Determine the tag kind
3439  ElaboratedTypeKeyword Keyword
3441 
3442  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3444  DTN->getQualifier(),
3445  DTN->getIdentifier(),
3446  TemplateArgs);
3447 
3448  // Build type-source information.
3449  TypeLocBuilder TLB;
3452  SpecTL.setElaboratedKeywordLoc(TagLoc);
3453  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3454  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3455  SpecTL.setTemplateNameLoc(TemplateLoc);
3456  SpecTL.setLAngleLoc(LAngleLoc);
3457  SpecTL.setRAngleLoc(RAngleLoc);
3458  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3459  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3460  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3461  }
3462 
3463  if (TypeAliasTemplateDecl *TAT =
3464  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
3465  // C++0x [dcl.type.elab]p2:
3466  // If the identifier resolves to a typedef-name or the simple-template-id
3467  // resolves to an alias template specialization, the
3468  // elaborated-type-specifier is ill-formed.
3469  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
3470  << TAT << NTK_TypeAliasTemplate << TagKind;
3471  Diag(TAT->getLocation(), diag::note_declared_at);
3472  }
3473 
3474  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
3475  if (Result.isNull())
3476  return TypeResult(true);
3477 
3478  // Check the tag kind
3479  if (const RecordType *RT = Result->getAs<RecordType>()) {
3480  RecordDecl *D = RT->getDecl();
3481 
3483  assert(Id && "templated class must have an identifier");
3484 
3485  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
3486  TagLoc, Id)) {
3487  Diag(TagLoc, diag::err_use_with_wrong_tag)
3488  << Result
3490  Diag(D->getLocation(), diag::note_previous_use);
3491  }
3492  }
3493 
3494  // Provide source-location information for the template specialization.
3495  TypeLocBuilder TLB;
3497  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3498  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3499  SpecTL.setTemplateNameLoc(TemplateLoc);
3500  SpecTL.setLAngleLoc(LAngleLoc);
3501  SpecTL.setRAngleLoc(RAngleLoc);
3502  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3503  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3504 
3505  // Construct an elaborated type containing the nested-name-specifier (if any)
3506  // and tag keyword.
3507  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
3508  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3509  ElabTL.setElaboratedKeywordLoc(TagLoc);
3510  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3511  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3512 }
3513 
3514 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
3515  NamedDecl *PrevDecl,
3516  SourceLocation Loc,
3518 
3520 
3522  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
3523  switch (Arg.getKind()) {
3530  return false;
3531 
3532  case TemplateArgument::Type: {
3533  QualType Type = Arg.getAsType();
3534  const TemplateTypeParmType *TPT =
3536  return TPT && !Type.hasQualifiers() &&
3537  TPT->getDepth() == Depth && TPT->getIndex() == Index;
3538  }
3539 
3541  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
3542  if (!DRE || !DRE->getDecl())
3543  return false;
3544  const NonTypeTemplateParmDecl *NTTP =
3545  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
3546  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
3547  }
3548 
3550  const TemplateTemplateParmDecl *TTP =
3551  dyn_cast_or_null<TemplateTemplateParmDecl>(
3553  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
3554  }
3555  llvm_unreachable("unexpected kind of template argument");
3556 }
3557 
3560  if (Params->size() != Args.size())
3561  return false;
3562 
3563  unsigned Depth = Params->getDepth();
3564 
3565  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
3566  TemplateArgument Arg = Args[I];
3567 
3568  // If the parameter is a pack expansion, the argument must be a pack
3569  // whose only element is a pack expansion.
3570  if (Params->getParam(I)->isParameterPack()) {
3571  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
3572  !Arg.pack_begin()->isPackExpansion())
3573  return false;
3574  Arg = Arg.pack_begin()->getPackExpansionPattern();
3575  }
3576 
3577  if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
3578  return false;
3579  }
3580 
3581  return true;
3582 }
3583 
3584 /// Convert the parser's template argument list representation into our form.
3587  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
3588  TemplateId.RAngleLoc);
3589  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
3590  TemplateId.NumArgs);
3591  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
3592  return TemplateArgs;
3593 }
3594 
3595 template<typename PartialSpecDecl>
3596 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
3597  if (Partial->getDeclContext()->isDependentContext())
3598  return;
3599 
3600  // FIXME: Get the TDK from deduction in order to provide better diagnostics
3601  // for non-substitution-failure issues?
3602  TemplateDeductionInfo Info(Partial->getLocation());
3603  if (S.isMoreSpecializedThanPrimary(Partial, Info))
3604  return;
3605 
3606  auto *Template = Partial->getSpecializedTemplate();
3607  S.Diag(Partial->getLocation(),
3608  diag::ext_partial_spec_not_more_specialized_than_primary)
3609  << isa<VarTemplateDecl>(Template);
3610 
3611  if (Info.hasSFINAEDiagnostic()) {
3614  Info.takeSFINAEDiagnostic(Diag);
3615  SmallString<128> SFINAEArgString;
3616  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
3617  S.Diag(Diag.first,
3618  diag::note_partial_spec_not_more_specialized_than_primary)
3619  << SFINAEArgString;
3620  }
3621 
3622  S.Diag(Template->getLocation(), diag::note_template_decl_here);
3623 }
3624 
3625 static void
3627  const llvm::SmallBitVector &DeducibleParams) {
3628  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
3629  if (!DeducibleParams[I]) {
3630  NamedDecl *Param = TemplateParams->getParam(I);
3631  if (Param->getDeclName())
3632  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3633  << Param->getDeclName();
3634  else
3635  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3636  << "(anonymous)";
3637  }
3638  }
3639 }
3640 
3641 
3642 template<typename PartialSpecDecl>
3644  PartialSpecDecl *Partial) {
3645  // C++1z [temp.class.spec]p8: (DR1495)
3646  // - The specialization shall be more specialized than the primary
3647  // template (14.5.5.2).
3648  checkMoreSpecializedThanPrimary(S, Partial);
3649 
3650  // C++ [temp.class.spec]p8: (DR1315)
3651  // - Each template-parameter shall appear at least once in the
3652  // template-id outside a non-deduced context.
3653  // C++1z [temp.class.spec.match]p3 (P0127R2)
3654  // If the template arguments of a partial specialization cannot be
3655  // deduced because of the structure of its template-parameter-list
3656  // and the template-id, the program is ill-formed.
3657  auto *TemplateParams = Partial->getTemplateParameters();
3658  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3659  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
3660  TemplateParams->getDepth(), DeducibleParams);
3661 
3662  if (!DeducibleParams.all()) {
3663  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3664  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
3665  << isa<VarTemplatePartialSpecializationDecl>(Partial)
3666  << (NumNonDeducible > 1)
3667  << SourceRange(Partial->getLocation(),
3668  Partial->getTemplateArgsAsWritten()->RAngleLoc);
3669  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
3670  }
3671 }
3672 
3675  checkTemplatePartialSpecialization(*this, Partial);
3676 }
3677 
3680  checkTemplatePartialSpecialization(*this, Partial);
3681 }
3682 
3684  // C++1z [temp.param]p11:
3685  // A template parameter of a deduction guide template that does not have a
3686  // default-argument shall be deducible from the parameter-type-list of the
3687  // deduction guide template.
3688  auto *TemplateParams = TD->getTemplateParameters();
3689  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3690  MarkDeducedTemplateParameters(TD, DeducibleParams);
3691  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
3692  // A parameter pack is deducible (to an empty pack).
3693  auto *Param = TemplateParams->getParam(I);
3694  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
3695  DeducibleParams[I] = true;
3696  }
3697 
3698  if (!DeducibleParams.all()) {
3699  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3700  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
3701  << (NumNonDeducible > 1);
3702  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
3703  }
3704 }
3705 
3707  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
3708  TemplateParameterList *TemplateParams, StorageClass SC,
3709  bool IsPartialSpecialization) {
3710  // D must be variable template id.
3712  "Variable template specialization is declared with a template it.");
3713 
3714  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
3715  TemplateArgumentListInfo TemplateArgs =
3716  makeTemplateArgumentListInfo(*this, *TemplateId);
3717  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
3718  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
3719  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
3720 
3721  TemplateName Name = TemplateId->Template.get();
3722 
3723  // The template-id must name a variable template.
3724  VarTemplateDecl *VarTemplate =
3725  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
3726  if (!VarTemplate) {
3727  NamedDecl *FnTemplate;
3728  if (auto *OTS = Name.getAsOverloadedTemplate())
3729  FnTemplate = *OTS->begin();
3730  else
3731  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
3732  if (FnTemplate)
3733  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
3734  << FnTemplate->getDeclName();
3735  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
3736  << IsPartialSpecialization;
3737  }
3738 
3739  // Check for unexpanded parameter packs in any of the template arguments.
3740  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
3741  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
3742  UPPC_PartialSpecialization))
3743  return true;
3744 
3745  // Check that the template argument list is well-formed for this
3746  // template.
3748  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
3749  false, Converted))
3750  return true;
3751 
3752  // Find the variable template (partial) specialization declaration that
3753  // corresponds to these arguments.
3754  if (IsPartialSpecialization) {
3755  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
3756  TemplateArgs.size(), Converted))
3757  return true;
3758 
3759  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
3760  // also do them during instantiation.
3761  bool InstantiationDependent;
3762  if (!Name.isDependent() &&
3764  TemplateArgs.arguments(),
3765  InstantiationDependent)) {
3766  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
3767  << VarTemplate->getDeclName();
3768  IsPartialSpecialization = false;
3769  }
3770 
3772  Converted)) {
3773  // C++ [temp.class.spec]p9b3:
3774  //
3775  // -- The argument list of the specialization shall not be identical
3776  // to the implicit argument list of the primary template.
3777  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
3778  << /*variable template*/ 1
3779  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
3780  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
3781  // FIXME: Recover from this by treating the declaration as a redeclaration
3782  // of the primary template.
3783  return true;
3784  }
3785  }
3786 
3787  void *InsertPos = nullptr;
3788  VarTemplateSpecializationDecl *PrevDecl = nullptr;
3789 
3790  if (IsPartialSpecialization)
3791  // FIXME: Template parameter list matters too
3792  PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
3793  else
3794  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
3795 
3796  VarTemplateSpecializationDecl *Specialization = nullptr;
3797 
3798  // Check whether we can declare a variable template specialization in
3799  // the current scope.
3800  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
3801  TemplateNameLoc,
3802  IsPartialSpecialization))
3803  return true;
3804 
3805  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
3806  // Since the only prior variable template specialization with these
3807  // arguments was referenced but not declared, reuse that
3808  // declaration node as our own, updating its source location and
3809  // the list of outer template parameters to reflect our new declaration.
3810  Specialization = PrevDecl;
3811  Specialization->setLocation(TemplateNameLoc);
3812  PrevDecl = nullptr;
3813  } else if (IsPartialSpecialization) {
3814  // Create a new class template partial specialization declaration node.
3816  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
3819  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
3820  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
3821  Converted, TemplateArgs);
3822 
3823  if (!PrevPartial)
3824  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
3825  Specialization = Partial;
3826 
3827  // If we are providing an explicit specialization of a member variable
3828  // template specialization, make a note of that.
3829  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
3830  PrevPartial->setMemberSpecialization();
3831 
3832  CheckTemplatePartialSpecialization(Partial);
3833  } else {
3834  // Create a new class template specialization declaration node for
3835  // this explicit specialization or friend declaration.
3836  Specialization = VarTemplateSpecializationDecl::Create(
3837  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
3838  VarTemplate, DI->getType(), DI, SC, Converted);
3839  Specialization->setTemplateArgsInfo(TemplateArgs);
3840 
3841  if (!PrevDecl)
3842  VarTemplate->AddSpecialization(Specialization, InsertPos);
3843  }
3844 
3845  // C++ [temp.expl.spec]p6:
3846  // If a template, a member template or the member of a class template is
3847  // explicitly specialized then that specialization shall be declared
3848  // before the first use of that specialization that would cause an implicit
3849  // instantiation to take place, in every translation unit in which such a
3850  // use occurs; no diagnostic is required.
3851  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
3852  bool Okay = false;
3853  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
3854  // Is there any previous explicit specialization declaration?
3856  Okay = true;
3857  break;
3858  }
3859  }
3860 
3861  if (!Okay) {
3862  SourceRange Range(TemplateNameLoc, RAngleLoc);
3863  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
3864  << Name << Range;
3865 
3866  Diag(PrevDecl->getPointOfInstantiation(),
3867  diag::note_instantiation_required_here)
3868  << (PrevDecl->getTemplateSpecializationKind() !=
3870  return true;
3871  }
3872  }
3873 
3874  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
3875  Specialization->setLexicalDeclContext(CurContext);
3876 
3877  // Add the specialization into its lexical context, so that it can
3878  // be seen when iterating through the list of declarations in that
3879  // context. However, specializations are not found by name lookup.
3880  CurContext->addDecl(Specialization);
3881 
3882  // Note that this is an explicit specialization.
3884 
3885  if (PrevDecl) {
3886  // Check that this isn't a redefinition of this specialization,
3887  // merging with previous declarations.
3888  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
3889  forRedeclarationInCurContext());
3890  PrevSpec.addDecl(PrevDecl);
3891  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
3892  } else if (Specialization->isStaticDataMember() &&
3893  Specialization->isOutOfLine()) {
3894  Specialization->setAccess(VarTemplate->getAccess());
3895  }
3896 
3897  // Link instantiations of static data members back to the template from
3898  // which they were instantiated.
3899  if (Specialization->isStaticDataMember())
3900  Specialization->setInstantiationOfStaticDataMember(
3901  VarTemplate->getTemplatedDecl(),
3902  Specialization->getSpecializationKind());
3903 
3904  return Specialization;
3905 }
3906 
3907 namespace {
3908 /// A partial specialization whose template arguments have matched
3909 /// a given template-id.
3910 struct PartialSpecMatchResult {
3912  TemplateArgumentList *Args;
3913 };
3914 } // end anonymous namespace
3915 
3916 DeclResult
3918  SourceLocation TemplateNameLoc,
3919  const TemplateArgumentListInfo &TemplateArgs) {
3920  assert(Template && "A variable template id without template?");
3921 
3922  // Check that the template argument list is well-formed for this template.
3924  if (CheckTemplateArgumentList(
3925  Template, TemplateNameLoc,
3926  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
3927  Converted))
3928  return true;
3929 
3930  // Find the variable template specialization declaration that
3931  // corresponds to these arguments.
3932  void *InsertPos = nullptr;
3933  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
3934  Converted, InsertPos)) {
3935  checkSpecializationVisibility(TemplateNameLoc, Spec);
3936  // If we already have a variable template specialization, return it.
3937  return Spec;
3938  }
3939 
3940  // This is the first time we have referenced this variable template
3941  // specialization. Create the canonical declaration and add it to
3942  // the set of specializations, based on the closest partial specialization
3943  // that it represents. That is,
3944  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
3946  Converted);
3947  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
3948  bool AmbiguousPartialSpec = false;
3949  typedef PartialSpecMatchResult MatchResult;
3951  SourceLocation PointOfInstantiation = TemplateNameLoc;
3952  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
3953  /*ForTakingAddress=*/false);
3954 
3955  // 1. Attempt to find the closest partial specialization that this
3956  // specializes, if any.
3957  // If any of the template arguments is dependent, then this is probably
3958  // a placeholder for an incomplete declarative context; which must be
3959  // complete by instantiation time. Thus, do not search through the partial
3960  // specializations yet.
3961  // TODO: Unify with InstantiateClassTemplateSpecialization()?
3962  // Perhaps better after unification of DeduceTemplateArguments() and
3963  // getMoreSpecializedPartialSpecialization().
3964  bool InstantiationDependent = false;
3966  TemplateArgs, InstantiationDependent)) {
3967 
3969  Template->getPartialSpecializations(PartialSpecs);
3970 
3971  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
3972  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
3973  TemplateDeductionInfo Info(FailedCandidates.getLocation());
3974 
3975  if (TemplateDeductionResult Result =
3976  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
3977  // Store the failed-deduction information for use in diagnostics, later.
3978  // TODO: Actually use the failed-deduction info?
3979  FailedCandidates.addCandidate().set(
3980  DeclAccessPair::make(Template, AS_public), Partial,
3981  MakeDeductionFailureInfo(Context, Result, Info));
3982  (void)Result;
3983  } else {
3984  Matched.push_back(PartialSpecMatchResult());
3985  Matched.back().Partial = Partial;
3986  Matched.back().Args = Info.take();
3987  }
3988  }
3989 
3990  if (Matched.size() >= 1) {
3991  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
3992  if (Matched.size() == 1) {
3993  // -- If exactly one matching specialization is found, the
3994  // instantiation is generated from that specialization.
3995  // We don't need to do anything for this.
3996  } else {
3997  // -- If more than one matching specialization is found, the
3998  // partial order rules (14.5.4.2) are used to determine
3999  // whether one of the specializations is more specialized
4000  // than the others. If none of the specializations is more
4001  // specialized than all of the other matching
4002  // specializations, then the use of the variable template is
4003  // ambiguous and the program is ill-formed.
4004  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4005  PEnd = Matched.end();
4006  P != PEnd; ++P) {
4007  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4008  PointOfInstantiation) ==
4009  P->Partial)
4010  Best = P;
4011  }
4012 
4013  // Determine if the best partial specialization is more specialized than
4014  // the others.
4015  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4016  PEnd = Matched.end();
4017  P != PEnd; ++P) {
4018  if (P != Best && getMoreSpecializedPartialSpecialization(
4019  P->Partial, Best->Partial,
4020  PointOfInstantiation) != Best->Partial) {
4021  AmbiguousPartialSpec = true;
4022  break;
4023  }
4024  }
4025  }
4026 
4027  // Instantiate using the best variable template partial specialization.
4028  InstantiationPattern = Best->Partial;
4029  InstantiationArgs = Best->Args;
4030  } else {
4031  // -- If no match is found, the instantiation is generated
4032  // from the primary template.
4033  // InstantiationPattern = Template->getTemplatedDecl();
4034  }
4035  }
4036 
4037  // 2. Create the canonical declaration.
4038  // Note that we do not instantiate a definition until we see an odr-use
4039  // in DoMarkVarDeclReferenced().
4040  // FIXME: LateAttrs et al.?
4041  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4042  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4043  Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
4044  if (!Decl)
4045  return true;
4046 
4047  if (AmbiguousPartialSpec) {
4048  // Partial ordering did not produce a clear winner. Complain.
4049  Decl->setInvalidDecl();
4050  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4051  << Decl;
4052 
4053  // Print the matching partial specializations.
4054  for (MatchResult P : Matched)
4055  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4056  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4057  *P.Args);
4058  return true;
4059  }
4060 
4062  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4063  Decl->setInstantiationOf(D, InstantiationArgs);
4064 
4065  checkSpecializationVisibility(TemplateNameLoc, Decl);
4066 
4067  assert(Decl && "No variable template specialization?");
4068  return Decl;
4069 }
4070 
4071 ExprResult
4073  const DeclarationNameInfo &NameInfo,
4074  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4075  const TemplateArgumentListInfo *TemplateArgs) {
4076 
4077  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4078  *TemplateArgs);
4079  if (Decl.isInvalid())
4080  return ExprError();
4081 
4082  VarDecl *Var = cast<VarDecl>(Decl.get());
4083  if (!Var->getTemplateSpecializationKind())
4085  NameInfo.getLoc());
4086 
4087  // Build an ordinary singleton decl ref.
4088  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4089  /*FoundD=*/nullptr, TemplateArgs);
4090 }
4091 
4093  SourceLocation Loc) {
4094  Diag(Loc, diag::err_template_missing_args)
4095  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4096  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4097  Diag(TD->getLocation(), diag::note_template_decl_here)
4098  << TD->getTemplateParameters()->getSourceRange();
4099  }
4100 }
4101 
4103  SourceLocation TemplateKWLoc,
4104  LookupResult &R,
4105  bool RequiresADL,
4106  const TemplateArgumentListInfo *TemplateArgs) {
4107  // FIXME: Can we do any checking at this point? I guess we could check the
4108  // template arguments that we have against the template name, if the template
4109  // name refers to a single template. That's not a terribly common case,
4110  // though.
4111  // foo<int> could identify a single function unambiguously
4112  // This approach does NOT work, since f<int>(1);
4113  // gets resolved prior to resorting to overload resolution
4114  // i.e., template<class T> void f(double);
4115  // vs template<class T, class U> void f(U);
4116 
4117  // These should be filtered out by our callers.
4118  assert(!R.empty() && "empty lookup results when building templateid");
4119  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4120 
4121  // Non-function templates require a template argument list.
4122  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4123  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4124  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4125  return ExprError();
4126  }
4127  }
4128 
4129  auto AnyDependentArguments = [&]() -> bool {
4130  bool InstantiationDependent;
4131  return TemplateArgs &&
4133  *TemplateArgs, InstantiationDependent);
4134  };
4135 
4136  // In C++1y, check variable template ids.
4137  if (R.getAsSingle<VarTemplateDecl>() && !AnyDependentArguments()) {
4138  return CheckVarTemplateId(SS, R.getLookupNameInfo(),
4140  TemplateKWLoc, TemplateArgs);
4141  }
4142 
4143  // We don't want lookup warnings at this point.
4144  R.suppressDiagnostics();
4145 
4148  SS.getWithLocInContext(Context),
4149  TemplateKWLoc,
4150  R.getLookupNameInfo(),
4151  RequiresADL, TemplateArgs,
4152  R.begin(), R.end());
4153 
4154  return ULE;
4155 }
4156 
4157 // We actually only call this from template instantiation.
4158 ExprResult
4160  SourceLocation TemplateKWLoc,
4161  const DeclarationNameInfo &NameInfo,
4162  const TemplateArgumentListInfo *TemplateArgs) {
4163 
4164  assert(TemplateArgs || TemplateKWLoc.isValid());
4165  DeclContext *DC;
4166  if (!(DC = computeDeclContext(SS, false)) ||
4167  DC->isDependentContext() ||
4168  RequireCompleteDeclContext(SS, DC))
4169  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4170 
4171  bool MemberOfUnknownSpecialization;
4172  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4173  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4174  /*Entering*/false, MemberOfUnknownSpecialization,
4175  TemplateKWLoc))
4176  return ExprError();
4177 
4178  if (R.isAmbiguous())
4179  return ExprError();
4180 
4181  if (R.empty()) {
4182  Diag(NameInfo.getLoc(), diag::err_no_member)
4183  << NameInfo.getName() << DC << SS.getRange();
4184  return ExprError();
4185  }
4186 
4187  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4188  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4189  << SS.getScopeRep()
4190  << NameInfo.getName().getAsString() << SS.getRange();
4191  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4192  return ExprError();
4193  }
4194 
4195  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4196 }
4197 
4198 /// Form a dependent template name.
4199 ///
4200 /// This action forms a dependent template name given the template
4201 /// name and its (presumably dependent) scope specifier. For
4202 /// example, given "MetaFun::template apply", the scope specifier \p
4203 /// SS will be "MetaFun::", \p TemplateKWLoc contains the location
4204 /// of the "template" keyword, and "apply" is the \p Name.
4206  CXXScopeSpec &SS,
4207  SourceLocation TemplateKWLoc,
4208  const UnqualifiedId &Name,
4209  ParsedType ObjectType,
4210  bool EnteringContext,
4211  TemplateTy &Result,
4212  bool AllowInjectedClassName) {
4213  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4214  Diag(TemplateKWLoc,
4215  getLangOpts().CPlusPlus11 ?
4216  diag::warn_cxx98_compat_template_outside_of_template :
4217  diag::ext_template_outside_of_template)
4218  << FixItHint::CreateRemoval(TemplateKWLoc);
4219 
4220  DeclContext *LookupCtx = nullptr;
4221  if (SS.isSet())
4222  LookupCtx = computeDeclContext(SS, EnteringContext);
4223  if (!LookupCtx && ObjectType)
4224  LookupCtx = computeDeclContext(ObjectType.get());
4225  if (LookupCtx) {
4226  // C++0x [temp.names]p5:
4227  // If a name prefixed by the keyword template is not the name of
4228  // a template, the program is ill-formed. [Note: the keyword
4229  // template may not be applied to non-template members of class
4230  // templates. -end note ] [ Note: as is the case with the
4231  // typename prefix, the template prefix is allowed in cases
4232  // where it is not strictly necessary; i.e., when the
4233  // nested-name-specifier or the expression on the left of the ->
4234  // or . is not dependent on a template-parameter, or the use
4235  // does not appear in the scope of a template. -end note]
4236  //
4237  // Note: C++03 was more strict here, because it banned the use of
4238  // the "template" keyword prior to a template-name that was not a
4239  // dependent name. C++ DR468 relaxed this requirement (the
4240  // "template" keyword is now permitted). We follow the C++0x
4241  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4242  bool MemberOfUnknownSpecialization;
4243  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4244  ObjectType, EnteringContext, Result,
4245  MemberOfUnknownSpecialization);
4246  if (TNK == TNK_Non_template && MemberOfUnknownSpecialization) {
4247  // This is a dependent template. Handle it below.
4248  } else if (TNK == TNK_Non_template) {
4249  // Do the lookup again to determine if this is a "nothing found" case or
4250  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4251  // need to do this.
4252  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4253  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4254  LookupOrdinaryName);
4255  bool MOUS;
4256  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext,
4257  MOUS, TemplateKWLoc))
4258  Diag(Name.getBeginLoc(), diag::err_no_member)
4259  << DNI.getName() << LookupCtx << SS.getRange();
4260  return TNK_Non_template;
4261  } else {
4262  // We found something; return it.
4263  auto *LookupRD = dyn_cast<CXXRecordDecl>(LookupCtx);
4264  if (!AllowInjectedClassName && SS.isSet() && LookupRD &&
4266  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4267  // C++14 [class.qual]p2:
4268  // In a lookup in which function names are not ignored and the
4269  // nested-name-specifier nominates a class C, if the name specified
4270  // [...] is the injected-class-name of C, [...] the name is instead
4271  // considered to name the constructor
4272  //
4273  // We don't get here if naming the constructor would be valid, so we
4274  // just reject immediately and recover by treating the
4275  // injected-class-name as naming the template.
4276  Diag(Name.getBeginLoc(),
4277  diag::ext_out_of_line_qualified_id_type_names_constructor)
4278  << Name.Identifier
4279  << 0 /*injected-class-name used as template name*/
4280  << 1 /*'template' keyword was used*/;
4281  }
4282  return TNK;
4283  }
4284  }
4285 
4286  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4287 
4288  switch (Name.getKind()) {
4290  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4291  Name.Identifier));
4293 
4295  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4297  return TNK_Function_template;
4298 
4300  llvm_unreachable("literal operator id cannot have a dependent scope");
4301 
4302  default:
4303  break;
4304  }
4305 
4306  Diag(Name.getBeginLoc(), diag::err_template_kw_refers_to_non_template)
4307  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4308  << TemplateKWLoc;
4309  return TNK_Non_template;
4310 }
4311 
4313  TemplateArgumentLoc &AL,
4314  SmallVectorImpl<TemplateArgument> &Converted) {
4315  const TemplateArgument &Arg = AL.getArgument();
4316  QualType ArgType;
4317  TypeSourceInfo *TSI = nullptr;
4318 
4319  // Check template type parameter.
4320  switch(Arg.getKind()) {
4322  // C++ [temp.arg.type]p1:
4323  // A template-argument for a template-parameter which is a
4324  // type shall be a type-id.
4325  ArgType = Arg.getAsType();
4326  TSI = AL.getTypeSourceInfo();
4327  break;
4330  // We have a template type parameter but the template argument
4331  // is a template without any arguments.
4332  SourceRange SR = AL.getSourceRange();
4334  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4335  return true;
4336  }
4338  // We have a template type parameter but the template argument is an
4339  // expression; see if maybe it is missing the "typename" keyword.
4340  CXXScopeSpec SS;
4341  DeclarationNameInfo NameInfo;
4342 
4343  if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
4344  SS.Adopt(ArgExpr->getQualifierLoc());
4345  NameInfo = ArgExpr->getNameInfo();
4346  } else if (DependentScopeDeclRefExpr *ArgExpr =
4347  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4348  SS.Adopt(ArgExpr->getQualifierLoc());
4349  NameInfo = ArgExpr->getNameInfo();
4350  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4351  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4352  if (ArgExpr->isImplicitAccess()) {
4353  SS.Adopt(ArgExpr->getQualifierLoc());
4354  NameInfo = ArgExpr->getMemberNameInfo();
4355  }
4356  }
4357 
4358  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4359  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4360  LookupParsedName(Result, CurScope, &SS);
4361 
4362  if (Result.getAsSingle<TypeDecl>() ||
4363  Result.getResultKind() ==
4365  // Suggest that the user add 'typename' before the NNS.
4366  SourceLocation Loc = AL.getSourceRange().getBegin();
4367  Diag(Loc, getLangOpts().MSVCCompat
4368  ? diag::ext_ms_template_type_arg_missing_typename
4369  : diag::err_template_arg_must_be_type_suggest)
4370  << FixItHint::CreateInsertion(Loc, "typename ");
4371  Diag(Param->getLocation(), diag::note_template_param_here);
4372 
4373  // Recover by synthesizing a type using the location information that we
4374  // already have.
4375  ArgType =
4376  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4377  TypeLocBuilder TLB;
4378  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4379  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4380  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4381  TL.setNameLoc(NameInfo.getLoc());
4382  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4383 
4384  // Overwrite our input TemplateArgumentLoc so that we can recover
4385  // properly.
4386  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
4388 
4389  break;
4390  }
4391  }
4392  // fallthrough
4393  LLVM_FALLTHROUGH;
4394  }
4395  default: {
4396  // We have a template type parameter but the template argument
4397  // is not a type.
4398  SourceRange SR = AL.getSourceRange();
4399  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
4400  Diag(Param->getLocation(), diag::note_template_param_here);
4401 
4402  return true;
4403  }
4404  }
4405 
4406  if (CheckTemplateArgument(Param, TSI))
4407  return true;
4408 
4409  // Add the converted template type argument.
4410  ArgType = Context.getCanonicalType(ArgType);
4411 
4412  // Objective-C ARC:
4413  // If an explicitly-specified template argument type is a lifetime type
4414  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
4415  if (getLangOpts().ObjCAutoRefCount &&
4416  ArgType->isObjCLifetimeType() &&
4417  !ArgType.getObjCLifetime()) {
4418  Qualifiers Qs;
4420  ArgType = Context.getQualifiedType(ArgType, Qs);
4421  }
4422 
4423  Converted.push_back(TemplateArgument(ArgType));
4424  return false;
4425 }
4426 
4427 /// Substitute template arguments into the default template argument for
4428 /// the given template type parameter.
4429 ///
4430 /// \param SemaRef the semantic analysis object for which we are performing
4431 /// the substitution.
4432 ///
4433 /// \param Template the template that we are synthesizing template arguments
4434 /// for.
4435 ///
4436 /// \param TemplateLoc the location of the template name that started the
4437 /// template-id we are checking.
4438 ///
4439 /// \param RAngleLoc the location of the right angle bracket ('>') that
4440 /// terminates the template-id.
4441 ///
4442 /// \param Param the template template parameter whose default we are
4443 /// substituting into.
4444 ///
4445 /// \param Converted the list of template arguments provided for template
4446 /// parameters that precede \p Param in the template parameter list.
4447 /// \returns the substituted template argument, or NULL if an error occurred.
4448 static TypeSourceInfo *
4450  TemplateDecl *Template,
4451  SourceLocation TemplateLoc,
4452  SourceLocation RAngleLoc,
4453  TemplateTypeParmDecl *Param,
4454  SmallVectorImpl<TemplateArgument> &Converted) {
4455  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
4456 
4457  // If the argument type is dependent, instantiate it now based
4458  // on the previously-computed template arguments.
4459  if (ArgType->getType()->isInstantiationDependentType()) {
4460  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4461  Param, Template, Converted,
4462  SourceRange(TemplateLoc, RAngleLoc));
4463  if (Inst.isInvalid())
4464  return nullptr;
4465 
4466  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4467 
4468  // Only substitute for the innermost template argument list.
4469  MultiLevelTemplateArgumentList TemplateArgLists;
4470  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4471  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4472  TemplateArgLists.addOuterTemplateArguments(None);
4473 
4474  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4475  ArgType =
4476  SemaRef.SubstType(ArgType, TemplateArgLists,
4477  Param->getDefaultArgumentLoc(), Param->getDeclName());
4478  }
4479 
4480  return ArgType;
4481 }
4482 
4483 /// Substitute template arguments into the default template argument for
4484 /// the given non-type template parameter.
4485 ///
4486 /// \param SemaRef the semantic analysis object for which we are performing
4487 /// the substitution.
4488 ///
4489 /// \param Template the template that we are synthesizing template arguments
4490 /// for.
4491 ///
4492 /// \param TemplateLoc the location of the template name that started the
4493 /// template-id we are checking.
4494 ///
4495 /// \param RAngleLoc the location of the right angle bracket ('>') that
4496 /// terminates the template-id.
4497 ///
4498 /// \param Param the non-type template parameter whose default we are
4499 /// substituting into.
4500 ///
4501 /// \param Converted the list of template arguments provided for template
4502 /// parameters that precede \p Param in the template parameter list.
4503 ///
4504 /// \returns the substituted template argument, or NULL if an error occurred.
4505 static ExprResult
4507  TemplateDecl *Template,
4508  SourceLocation TemplateLoc,
4509  SourceLocation RAngleLoc,
4510  NonTypeTemplateParmDecl *Param,
4511  SmallVectorImpl<TemplateArgument> &Converted) {
4512  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4513  Param, Template, Converted,
4514  SourceRange(TemplateLoc, RAngleLoc));
4515  if (Inst.isInvalid())
4516  return ExprError();
4517 
4518  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4519 
4520  // Only substitute for the innermost template argument list.
4521  MultiLevelTemplateArgumentList TemplateArgLists;
4522  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4523  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4524  TemplateArgLists.addOuterTemplateArguments(None);
4525 
4526  EnterExpressionEvaluationContext ConstantEvaluated(
4528  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
4529 }
4530 
4531 /// Substitute template arguments into the default template argument for
4532 /// the given template template parameter.
4533 ///
4534 /// \param SemaRef the semantic analysis object for which we are performing
4535 /// the substitution.
4536 ///
4537 /// \param Template the template that we are synthesizing template arguments
4538 /// for.
4539 ///
4540 /// \param TemplateLoc the location of the template name that started the
4541 /// template-id we are checking.
4542 ///
4543 /// \param RAngleLoc the location of the right angle bracket ('>') that
4544 /// terminates the template-id.
4545 ///
4546 /// \param Param the template template parameter whose default we are
4547 /// substituting into.
4548 ///
4549 /// \param Converted the list of template arguments provided for template
4550 /// parameters that precede \p Param in the template parameter list.
4551 ///
4552 /// \param QualifierLoc Will be set to the nested-name-specifier (with
4553 /// source-location information) that precedes the template name.
4554 ///
4555 /// \returns the substituted template argument, or NULL if an error occurred.
4556 static TemplateName
4558  TemplateDecl *Template,
4559  SourceLocation TemplateLoc,
4560  SourceLocation RAngleLoc,
4561  TemplateTemplateParmDecl *Param,
4563  NestedNameSpecifierLoc &QualifierLoc) {
4565  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
4566  SourceRange(TemplateLoc, RAngleLoc));
4567  if (Inst.isInvalid())
4568  return TemplateName();
4569 
4570  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4571 
4572  // Only substitute for the innermost template argument list.
4573  MultiLevelTemplateArgumentList TemplateArgLists;
4574  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4575  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4576  TemplateArgLists.addOuterTemplateArguments(None);
4577 
4578  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4579  // Substitute into the nested-name-specifier first,
4580  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
4581  if (QualifierLoc) {
4582  QualifierLoc =
4583  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
4584  if (!QualifierLoc)
4585  return TemplateName();
4586  }
4587 
4588  return SemaRef.SubstTemplateName(
4589  QualifierLoc,
4592  TemplateArgLists);
4593 }
4594 
4595 /// If the given template parameter has a default template
4596 /// argument, substitute into that default template argument and
4597 /// return the corresponding template argument.
4600  SourceLocation TemplateLoc,
4601  SourceLocation RAngleLoc,
4602  Decl *Param,
4604  &Converted,
4605  bool &HasDefaultArg) {
4606  HasDefaultArg = false;
4607 
4608  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
4609  if (!hasVisibleDefaultArgument(TypeParm))
4610  return TemplateArgumentLoc();
4611 
4612  HasDefaultArg = true;
4613  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
4614  TemplateLoc,
4615  RAngleLoc,
4616  TypeParm,
4617  Converted);
4618  if (DI)
4619  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
4620 
4621  return TemplateArgumentLoc();
4622  }
4623 
4624  if (NonTypeTemplateParmDecl *NonTypeParm
4625  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4626  if (!hasVisibleDefaultArgument(NonTypeParm))
4627  return TemplateArgumentLoc();
4628 
4629  HasDefaultArg = true;
4630  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
4631  TemplateLoc,
4632  RAngleLoc,
4633  NonTypeParm,
4634  Converted);
4635  if (Arg.isInvalid())
4636  return TemplateArgumentLoc();
4637 
4638  Expr *ArgE = Arg.getAs<Expr>();
4639  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
4640  }
4641 
4642  TemplateTemplateParmDecl *TempTempParm
4643  = cast<TemplateTemplateParmDecl>(Param);
4644  if (!hasVisibleDefaultArgument(TempTempParm))
4645  return TemplateArgumentLoc();
4646 
4647  HasDefaultArg = true;
4648  NestedNameSpecifierLoc QualifierLoc;
4649  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
4650  TemplateLoc,
4651  RAngleLoc,
4652  TempTempParm,
4653  Converted,
4654  QualifierLoc);
4655  if (TName.isNull())
4656  return TemplateArgumentLoc();
4657 
4658  return TemplateArgumentLoc(TemplateArgument(TName),
4659  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
4660  TempTempParm->getDefaultArgument().getTemplateNameLoc());
4661 }
4662 
4663 /// Convert a template-argument that we parsed as a type into a template, if
4664 /// possible. C++ permits injected-class-names to perform dual service as
4665 /// template template arguments and as template type arguments.
4667  // Extract and step over any surrounding nested-name-specifier.
4668  NestedNameSpecifierLoc QualLoc;
4669  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
4670  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
4671  return TemplateArgumentLoc();
4672 
4673  QualLoc = ETLoc.getQualifierLoc();
4674  TLoc = ETLoc.getNamedTypeLoc();
4675  }
4676 
4677  // If this type was written as an injected-class-name, it can be used as a
4678  // template template argument.
4679  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
4680  return TemplateArgumentLoc(InjLoc.getTypePtr()->getTemplateName(),
4681  QualLoc, InjLoc.getNameLoc());
4682 
4683  // If this type was written as an injected-class-name, it may have been
4684  // converted to a RecordType during instantiation. If the RecordType is
4685  // *not* wrapped in a TemplateSpecializationType and denotes a class
4686  // template specialization, it must have come from an injected-class-name.
4687  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
4688  if (auto *CTSD =
4689  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
4690  return TemplateArgumentLoc(TemplateName(CTSD->getSpecializedTemplate()),
4691  QualLoc, RecLoc.getNameLoc());
4692 
4693  return TemplateArgumentLoc();
4694 }
4695 
4696 /// Check that the given template argument corresponds to the given
4697 /// template parameter.
4698 ///
4699 /// \param Param The template parameter against which the argument will be
4700 /// checked.
4701 ///
4702 /// \param Arg The template argument, which may be updated due to conversions.
4703 ///
4704 /// \param Template The template in which the template argument resides.
4705 ///
4706 /// \param TemplateLoc The location of the template name for the template
4707 /// whose argument list we're matching.
4708 ///
4709 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
4710 /// the template argument list.
4711 ///
4712 /// \param ArgumentPackIndex The index into the argument pack where this
4713 /// argument will be placed. Only valid if the parameter is a parameter pack.
4714 ///
4715 /// \param Converted The checked, converted argument will be added to the
4716 /// end of this small vector.
4717 ///
4718 /// \param CTAK Describes how we arrived at this particular template argument:
4719 /// explicitly written, deduced, etc.
4720 ///
4721 /// \returns true on error, false otherwise.
4723  TemplateArgumentLoc &Arg,
4724  NamedDecl *Template,
4725  SourceLocation TemplateLoc,
4726  SourceLocation RAngleLoc,
4727  unsigned ArgumentPackIndex,
4730  // Check template type parameters.
4731  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
4732  return CheckTemplateTypeArgument(TTP, Arg, Converted);
4733 
4734  // Check non-type template parameters.
4735  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4736  // Do substitution on the type of the non-type template parameter
4737  // with the template arguments we've seen thus far. But if the
4738  // template has a dependent context then we cannot substitute yet.
4739  QualType NTTPType = NTTP->getType();
4740  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
4741  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
4742 
4743  // FIXME: Do we need to substitute into parameters here if they're
4744  // instantiation-dependent but not dependent?
4745  if (NTTPType->isDependentType() &&
4746  !isa<TemplateTemplateParmDecl>(Template) &&
4747  !Template->getDeclContext()->isDependentContext()) {
4748  // Do substitution on the type of the non-type template parameter.
4749  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4750  NTTP, Converted,
4751  SourceRange(TemplateLoc, RAngleLoc));
4752  if (Inst.isInvalid())
4753  return true;
4754 
4756  Converted);
4757  NTTPType = SubstType(NTTPType,
4758  MultiLevelTemplateArgumentList(TemplateArgs),
4759  NTTP->getLocation(),
4760  NTTP->getDeclName());
4761  // If that worked, check the non-type template parameter type
4762  // for validity.
4763  if (!NTTPType.isNull())
4764  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
4765  NTTP->getLocation());
4766  if (NTTPType.isNull())
4767  return true;
4768  }
4769 
4770  switch (Arg.getArgument().getKind()) {
4772  llvm_unreachable("Should never see a NULL template argument here");
4773 
4775  TemplateArgument Result;
4776  unsigned CurSFINAEErrors = NumSFINAEErrors;
4777  ExprResult Res =
4778  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
4779  Result, CTAK);
4780  if (Res.isInvalid())
4781  return true;
4782  // If the current template argument causes an error, give up now.
4783  if (CurSFINAEErrors < NumSFINAEErrors)
4784  return true;
4785 
4786  // If the resulting expression is new, then use it in place of the
4787  // old expression in the template argument.
4788  if (Res.get() != Arg.getArgument().getAsExpr()) {
4789  TemplateArgument TA(Res.get());
4790  Arg = TemplateArgumentLoc(TA, Res.get());
4791  }
4792 
4793  Converted.push_back(Result);
4794  break;
4795  }
4796 
4800  // We've already checked this template argument, so just copy
4801  // it to the list of converted arguments.
4802  Converted.push_back(Arg.getArgument());
4803  break;
4804 
4807  // We were given a template template argument. It may not be ill-formed;
4808  // see below.
4809  if (DependentTemplateName *DTN
4812  // We have a template argument such as \c T::template X, which we
4813  // parsed as a template template argument. However, since we now
4814  // know that we need a non-type template argument, convert this
4815  // template name into an expression.
4816 
4817  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
4818  Arg.getTemplateNameLoc());
4819 
4820  CXXScopeSpec SS;
4821  SS.Adopt(Arg.getTemplateQualifierLoc());
4822  // FIXME: the template-template arg was a DependentTemplateName,
4823  // so it was provided with a template keyword. However, its source
4824  // location is not stored in the template argument structure.
4825  SourceLocation TemplateKWLoc;
4827  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
4828  nullptr);
4829 
4830  // If we parsed the template argument as a pack expansion, create a
4831  // pack expansion expression.
4833  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
4834  if (E.isInvalid())
4835  return true;
4836  }
4837 
4838  TemplateArgument Result;
4839  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
4840  if (E.isInvalid())
4841  return true;
4842 
4843  Converted.push_back(Result);
4844  break;
4845  }
4846 
4847  // We have a template argument that actually does refer to a class
4848  // template, alias template, or template template parameter, and
4849  // therefore cannot be a non-type template argument.
4850  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
4851  << Arg.getSourceRange();
4852 
4853  Diag(Param->getLocation(), diag::note_template_param_here);
4854  return true;
4855 
4856  case TemplateArgument::Type: {
4857  // We have a non-type template parameter but the template
4858  // argument is a type.
4859 
4860  // C++ [temp.arg]p2:
4861  // In a template-argument, an ambiguity between a type-id and
4862  // an expression is resolved to a type-id, regardless of the
4863  // form of the corresponding template-parameter.
4864  //
4865  // We warn specifically about this case, since it can be rather
4866  // confusing for users.
4867  QualType T = Arg.getArgument().getAsType();
4868  SourceRange SR = Arg.getSourceRange();
4869  if (T->isFunctionType())
4870  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
4871  else
4872  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
4873  Diag(Param->getLocation(), diag::note_template_param_here);
4874  return true;
4875  }
4876 
4878  llvm_unreachable("Caller must expand template argument packs");
4879  }
4880 
4881  return false;
4882  }
4883 
4884 
4885  // Check template template parameters.
4886  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
4887 
4888  TemplateParameterList *Params = TempParm->getTemplateParameters();
4889  if (TempParm->isExpandedParameterPack())
4890  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
4891 
4892  // Substitute into the template parameter list of the template
4893  // template parameter, since previously-supplied template arguments
4894  // may appear within the template template parameter.
4895  //
4896  // FIXME: Skip this if the parameters aren't instantiation-dependent.
4897  {
4898  // Set up a template instantiation context.
4900  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4901  TempParm, Converted,
4902  SourceRange(TemplateLoc, RAngleLoc));
4903  if (Inst.isInvalid())
4904  return true;
4905 
4906  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4907  Params = SubstTemplateParams(Params, CurContext,
4908  MultiLevelTemplateArgumentList(TemplateArgs));
4909  if (!Params)
4910  return true;
4911  }
4912 
4913  // C++1z [temp.local]p1: (DR1004)
4914  // When [the injected-class-name] is used [...] as a template-argument for
4915  // a template template-parameter [...] it refers to the class template
4916  // itself.
4917  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
4919  Arg.getTypeSourceInfo()->getTypeLoc());
4920  if (!ConvertedArg.getArgument().isNull())
4921  Arg = ConvertedArg;
4922  }
4923 
4924  switch (Arg.getArgument().getKind()) {
4926  llvm_unreachable("Should never see a NULL template argument here");
4927 
4930  if (CheckTemplateTemplateArgument(Params, Arg))
4931  return true;
4932 
4933  Converted.push_back(Arg.getArgument());
4934  break;
4935 
4938  // We have a template template parameter but the template
4939  // argument does not refer to a template.
4940  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
4941  << getLangOpts().CPlusPlus11;
4942  return true;
4943 
4945  llvm_unreachable("Declaration argument with template template parameter");
4947  llvm_unreachable("Integral argument with template template parameter");
4949  llvm_unreachable("Null pointer argument with template template parameter");
4950 
4952  llvm_unreachable("Caller must expand template argument packs");
4953  }
4954 
4955  return false;
4956 }
4957 
4958 /// Check whether the template parameter is a pack expansion, and if so,
4959 /// determine the number of parameters produced by that expansion. For instance:
4960 ///
4961 /// \code
4962 /// template<typename ...Ts> struct A {
4963 /// template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
4964 /// };
4965 /// \endcode
4966 ///
4967 /// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
4968 /// is not a pack expansion, so returns an empty Optional.
4970  if (NonTypeTemplateParmDecl *NTTP
4971  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4972  if (NTTP->isExpandedParameterPack())
4973  return NTTP->getNumExpansionTypes();
4974  }
4975 
4976  if (TemplateTemplateParmDecl *TTP
4977  = dyn_cast<TemplateTemplateParmDecl>(Param)) {
4978  if (TTP->isExpandedParameterPack())
4979  return TTP->getNumExpansionTemplateParameters();
4980  }
4981 
4982  return None;
4983 }
4984 
4985 /// Diagnose a missing template argument.
4986 template<typename TemplateParmDecl>
4988  TemplateDecl *TD,
4989  const TemplateParmDecl *D,
4990  TemplateArgumentListInfo &Args) {
4991  // Dig out the most recent declaration of the template parameter; there may be
4992  // declarations of the template that are more recent than TD.
4993  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
4994  ->getTemplateParameters()
4995  ->getParam(D->getIndex()));
4996 
4997  // If there's a default argument that's not visible, diagnose that we're
4998  // missing a module import.
5000  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5001  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5002  D->getDefaultArgumentLoc(), Modules,
5004  /*Recover*/true);
5005  return true;
5006  }
5007 
5008  // FIXME: If there's a more recent default argument that *is* visible,
5009  // diagnose that it was declared too late.
5010 
5012 
5013  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5014  << /*not enough args*/0
5016  << TD;
5017  S.Diag(TD->getLocation(), diag::note_template_decl_here)
5018  << Params->getSourceRange();
5019  return true;
5020 }
5021 
5022 /// Check that the given template argument list is well-formed
5023 /// for specializing the given template.
5025  TemplateDecl *Template, SourceLocation TemplateLoc,
5026  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
5028  bool UpdateArgsWithConversions) {
5029  // Make a copy of the template arguments for processing. Only make the
5030  // changes at the end when successful in matching the arguments to the
5031  // template.
5032  TemplateArgumentListInfo NewArgs = TemplateArgs;
5033 
5034  // Make sure we get the template parameter list from the most
5035  // recentdeclaration, since that is the only one that has is guaranteed to
5036  // have all the default template argument information.
5037  TemplateParameterList *Params =
5038  cast<TemplateDecl>(Template->getMostRecentDecl())
5039  ->getTemplateParameters();
5040 
5041  SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
5042 
5043  // C++ [temp.arg]p1:
5044  // [...] The type and form of each template-argument specified in
5045  // a template-id shall match the type and form specified for the
5046  // corresponding parameter declared by the template in its
5047  // template-parameter-list.
5048  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
5049  SmallVector<TemplateArgument, 2> ArgumentPack;
5050  unsigned ArgIdx = 0, NumArgs = NewArgs.size();
5051  LocalInstantiationScope InstScope(*this, true);
5052  for (TemplateParameterList::iterator Param = Params->begin(),
5053  ParamEnd = Params->end();
5054  Param != ParamEnd; /* increment in loop */) {
5055  // If we have an expanded parameter pack, make sure we don't have too
5056  // many arguments.
5057  if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
5058  if (*Expansions == ArgumentPack.size()) {
5059  // We're done with this parameter pack. Pack up its arguments and add
5060  // them to the list.
5061  Converted.push_back(
5062  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5063  ArgumentPack.clear();
5064 
5065  // This argument is assigned to the next parameter.
5066  ++Param;
5067  continue;
5068  } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
5069  // Not enough arguments for this parameter pack.
5070  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5071  << /*not enough args*/0
5072  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5073  << Template;
5074  Diag(Template->getLocation(), diag::note_template_decl_here)
5075  << Params->getSourceRange();
5076  return true;
5077  }
5078  }
5079 
5080  if (ArgIdx < NumArgs) {
5081  // Check the template argument we were given.
5082  if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
5083  TemplateLoc, RAngleLoc,
5084  ArgumentPack.size(), Converted))
5085  return true;
5086 
5087  bool PackExpansionIntoNonPack =
5088  NewArgs[ArgIdx].getArgument().isPackExpansion() &&
5089  (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
5090  if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
5091  // Core issue 1430: we have a pack expansion as an argument to an
5092  // alias template, and it's not part of a parameter pack. This
5093  // can't be canonicalized, so reject it now.
5094  Diag(NewArgs[ArgIdx].getLocation(),
5095  diag::err_alias_template_expansion_into_fixed_list)
5096  << NewArgs[ArgIdx].getSourceRange();
5097  Diag((*Param)->getLocation(), diag::note_template_param_here);
5098  return true;
5099  }
5100 
5101  // We're now done with this argument.
5102  ++ArgIdx;
5103 
5104  if ((*Param)->isTemplateParameterPack()) {
5105  // The template parameter was a template parameter pack, so take the
5106  // deduced argument and place it on the argument pack. Note that we
5107  // stay on the same template parameter so that we can deduce more
5108  // arguments.
5109  ArgumentPack.push_back(Converted.pop_back_val());
5110  } else {
5111  // Move to the next template parameter.
5112  ++Param;
5113  }
5114 
5115  // If we just saw a pack expansion into a non-pack, then directly convert
5116  // the remaining arguments, because we don't know what parameters they'll
5117  // match up with.
5118  if (PackExpansionIntoNonPack) {
5119  if (!ArgumentPack.empty()) {
5120  // If we were part way through filling in an expanded parameter pack,
5121  // fall back to just producing individual arguments.
5122  Converted.insert(Converted.end(),
5123  ArgumentPack.begin(), ArgumentPack.end());
5124  ArgumentPack.clear();
5125  }
5126 
5127  while (ArgIdx < NumArgs) {
5128  Converted.push_back(NewArgs[ArgIdx].getArgument());
5129  ++ArgIdx;
5130  }
5131 
5132  return false;
5133  }
5134 
5135  continue;
5136  }
5137 
5138  // If we're checking a partial template argument list, we're done.
5139  if (PartialTemplateArgs) {
5140  if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
5141  Converted.push_back(
5142  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5143 
5144  return false;
5145  }
5146 
5147  // If we have a template parameter pack with no more corresponding
5148  // arguments, just break out now and we'll fill in the argument pack below.
5149  if ((*Param)->isTemplateParameterPack()) {
5150  assert(!getExpandedPackSize(*Param) &&
5151  "Should have dealt with this already");
5152 
5153  // A non-expanded parameter pack before the end of the parameter list
5154  // only occurs for an ill-formed template parameter list, unless we've
5155  // got a partial argument list for a function template, so just bail out.
5156  if (Param + 1 != ParamEnd)
5157  return true;
5158 
5159  Converted.push_back(
5160  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5161  ArgumentPack.clear();
5162 
5163  ++Param;
5164  continue;
5165  }
5166 
5167  // Check whether we have a default argument.
5168  TemplateArgumentLoc Arg;
5169 
5170  // Retrieve the default template argument from the template
5171  // parameter. For each kind of template parameter, we substitute the
5172  // template arguments provided thus far and any "outer" template arguments
5173  // (when the template parameter was part of a nested template) into
5174  // the default argument.
5175  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
5176  if (!hasVisibleDefaultArgument(TTP))
5177  return diagnoseMissingArgument(*this, TemplateLoc, Template, TTP,
5178  NewArgs);
5179 
5181  Template,
5182  TemplateLoc,
5183  RAngleLoc,
5184  TTP,
5185  Converted);
5186  if (!ArgType)
5187  return true;
5188 
5189  Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
5190  ArgType);
5191  } else if (NonTypeTemplateParmDecl *NTTP
5192  = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
5193  if (!hasVisibleDefaultArgument(NTTP))
5194  return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
5195  NewArgs);
5196 
5197  ExprResult E = SubstDefaultTemplateArgument(*this, Template,
5198  TemplateLoc,
5199  RAngleLoc,
5200  NTTP,
5201  Converted);
5202  if (E.isInvalid())
5203  return true;
5204 
5205  Expr *Ex = E.getAs<Expr>();
5206  Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
5207  } else {
5208  TemplateTemplateParmDecl *TempParm
5209  = cast<TemplateTemplateParmDecl>(*Param);
5210 
5211  if (!hasVisibleDefaultArgument(TempParm))
5212  return diagnoseMissingArgument(*this, TemplateLoc, Template, TempParm,
5213  NewArgs);
5214 
5215  NestedNameSpecifierLoc QualifierLoc;
5216  TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
5217  TemplateLoc,
5218  RAngleLoc,
5219  TempParm,
5220  Converted,
5221  QualifierLoc);
5222  if (Name.isNull())
5223  return true;
5224 
5225  Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
5226  TempParm->getDefaultArgument().getTemplateNameLoc());
5227  }
5228 
5229  // Introduce an instantiation record that describes where we are using
5230  // the default template argument. We're not actually instantiating a
5231  // template here, we just create this object to put a note into the
5232  // context stack.
5233  InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
5234  SourceRange(TemplateLoc, RAngleLoc));
5235  if (Inst.isInvalid())
5236  return true;
5237 
5238  // Check the default template argument.
5239  if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
5240  RAngleLoc, 0, Converted))
5241  return true;
5242 
5243  // Core issue 150 (assumed resolution): if this is a template template
5244  // parameter, keep track of the default template arguments from the
5245  // template definition.
5246  if (isTemplateTemplateParameter)
5247  NewArgs.addArgument(Arg);
5248 
5249  // Move to the next template parameter and argument.
5250  ++Param;
5251  ++ArgIdx;
5252  }
5253 
5254  // If we're performing a partial argument substitution, allow any trailing
5255  // pack expansions; they might be empty. This can happen even if
5256  // PartialTemplateArgs is false (the list of arguments is complete but
5257  // still dependent).
5258  if (ArgIdx < NumArgs && CurrentInstantiationScope &&
5259  CurrentInstantiationScope->getPartiallySubstitutedPack()) {
5260  while (ArgIdx < NumArgs && NewArgs[ArgIdx].getArgument().isPackExpansion())
5261  Converted.push_back(NewArgs[ArgIdx++].getArgument());
5262  }
5263 
5264  // If we have any leftover arguments, then there were too many arguments.
5265  // Complain and fail.
5266  if (ArgIdx < NumArgs) {
5267  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5268  << /*too many args*/1
5269  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5270  << Template
5271  << SourceRange(NewArgs[ArgIdx].getLocation(), NewArgs.getRAngleLoc());
5272  Diag(Template->getLocation(), diag::note_template_decl_here)
5273  << Params->getSourceRange();
5274  return true;
5275  }
5276 
5277  // No problems found with the new argument list, propagate changes back
5278  // to caller.
5279  if (UpdateArgsWithConversions)
5280  TemplateArgs = std::move(NewArgs);
5281 
5282  return false;
5283 }
5284 
5285 namespace {
5286  class UnnamedLocalNoLinkageFinder
5287  : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
5288  {
5289  Sema &S;
5290  SourceRange SR;
5291 
5293 
5294  public:
5295  UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
5296 
5297  bool Visit(QualType T) {
5298  return T.isNull() ? false : inherited::Visit(T.getTypePtr());
5299  }
5300 
5301 #define TYPE(Class, Parent) \
5302  bool Visit##Class##Type(const Class##Type *);
5303 #define ABSTRACT_TYPE(Class, Parent) \
5304  bool Visit##Class##Type(const Class##Type *) { return false; }
5305 #define NON_CANONICAL_TYPE(Class, Parent) \
5306  bool Visit##Class##Type(const Class##Type *) { return false; }
5307 #include "clang/AST/TypeNodes.def"
5308 
5309  bool VisitTagDecl(const TagDecl *Tag);
5310  bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
5311  };
5312 } // end anonymous namespace
5313 
5314 bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
5315  return false;
5316 }
5317 
5318 bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
5319  return Visit(T->getElementType());
5320 }
5321 
5322 bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
5323  return Visit(T->getPointeeType());
5324 }
5325 
5326 bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
5327  const BlockPointerType* T) {
5328  return Visit(T->getPointeeType());
5329 }
5330 
5331 bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
5332  const LValueReferenceType* T) {
5333  return Visit(T->getPointeeType());
5334 }
5335 
5336 bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
5337  const RValueReferenceType* T) {
5338  return Visit(T->getPointeeType());
5339 }
5340 
5341 bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
5342  const MemberPointerType* T) {
5343  return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
5344 }
5345 
5346 bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
5347  const ConstantArrayType* T) {
5348  return Visit(T->getElementType());
5349 }
5350 
5351 bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
5352  const IncompleteArrayType* T) {
5353  return Visit(T->getElementType());
5354 }
5355 
5356 bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
5357  const VariableArrayType* T) {
5358  return Visit(T->getElementType());
5359 }
5360 
5361 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
5362  const DependentSizedArrayType* T) {
5363  return Visit(T->getElementType());
5364 }
5365 
5366 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
5367  const DependentSizedExtVectorType* T) {
5368  return Visit(T->getElementType());
5369 }
5370 
5371 bool UnnamedLocalNoLinkageFinder::VisitDependentAddressSpaceType(
5372  const DependentAddressSpaceType *T) {
5373  return Visit(T->getPointeeType());
5374 }
5375 
5376 bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
5377  return Visit(T->getElementType());
5378 }
5379 
5380 bool UnnamedLocalNoLinkageFinder::VisitDependentVectorType(
5381  const DependentVectorType *T) {
5382  return Visit(T->getElementType());
5383 }
5384 
5385 bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
5386  return Visit(T->getElementType());
5387 }
5388 
5389 bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
5390  const FunctionProtoType* T) {
5391  for (const auto &A : T->param_types()) {
5392  if (Visit(A))
5393  return true;
5394  }
5395 
5396  return Visit(T->getReturnType());
5397 }
5398 
5399 bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
5400  const FunctionNoProtoType* T) {
5401  return Visit(T->getReturnType());
5402 }
5403 
5404 bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
5405  const UnresolvedUsingType*) {
5406  return false;
5407 }
5408 
5409 bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
5410  return false;
5411 }
5412 
5413 bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
5414  return Visit(T->getUnderlyingType());
5415 }
5416 
5417 bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
5418  return false;
5419 }
5420 
5421 bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
5422  const UnaryTransformType*) {
5423  return false;
5424 }
5425 
5426 bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
5427  return Visit(T->getDeducedType());
5428 }
5429 
5430 bool UnnamedLocalNoLinkageFinder::VisitDeducedTemplateSpecializationType(
5432  return Visit(T->getDeducedType());
5433 }
5434 
5435 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
5436  return VisitTagDecl(T->getDecl());
5437 }
5438 
5439 bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
5440  return VisitTagDecl(T->getDecl());
5441 }
5442 
5443 bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
5444  const TemplateTypeParmType*) {
5445  return false;
5446 }
5447 
5448 bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
5450  return false;
5451 }
5452 
5453 bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
5454  const TemplateSpecializationType*) {
5455  return false;
5456 }
5457 
5458 bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
5459  const InjectedClassNameType* T) {
5460  return VisitTagDecl(T->getDecl());
5461 }
5462 
5463 bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
5464  const DependentNameType* T) {
5465  return VisitNestedNameSpecifier(T->getQualifier());
5466 }
5467 
5468 bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
5470  return VisitNestedNameSpecifier(T->getQualifier());
5471 }
5472 
5473 bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
5474  const PackExpansionType* T) {
5475  return Visit(T->getPattern());
5476 }
5477 
5478 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
5479  return false;
5480 }
5481 
5482 bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
5483  const ObjCInterfaceType *) {
5484  return false;
5485 }
5486 
5487 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
5488  const ObjCObjectPointerType *) {
5489  return false;
5490 }
5491 
5492 bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
5493  return Visit(T->getValueType());
5494 }
5495 
5496 bool UnnamedLocalNoLinkageFinder::VisitPipeType(const PipeType* T) {
5497  return false;
5498 }
5499 
5500 bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
5501  if (Tag->getDeclContext()->isFunctionOrMethod()) {
5502  S.Diag(SR.getBegin(),
5503  S.getLangOpts().CPlusPlus11 ?
5504  diag::warn_cxx98_compat_template_arg_local_type :
5505  diag::ext_template_arg_local_type)
5506  << S.Context.getTypeDeclType(Tag) << SR;
5507  return true;
5508  }
5509 
5510  if (!Tag->hasNameForLinkage()) {
5511  S.Diag(SR.getBegin(),
5512  S.getLangOpts().CPlusPlus11 ?
5513  diag::warn_cxx98_compat_template_arg_unnamed_type :
5514  diag::ext_template_arg_unnamed_type) << SR;
5515  S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
5516  return true;
5517  }
5518 
5519  return false;
5520 }
5521 
5522 bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
5523  NestedNameSpecifier *NNS) {
5524  if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
5525  return true;
5526 
5527  switch (NNS->getKind()) {
5533  return false;
5534 
5537  return Visit(QualType(NNS->getAsType(), 0));
5538  }
5539  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
5540 }
5541 
5542 /// Check a template argument against its corresponding
5543 /// template type parameter.
5544 ///
5545 /// This routine implements the semantics of C++ [temp.arg.type]. It
5546 /// returns true if an error occurred, and false otherwise.
5548  TypeSourceInfo *ArgInfo) {
5549  assert(ArgInfo && "invalid TypeSourceInfo");
5550  QualType Arg = ArgInfo->getType();
5551  SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
5552 
5553  if (Arg->isVariablyModifiedType()) {
5554  return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
5555  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
5556  return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
5557  }
5558 
5559  // C++03 [temp.arg.type]p2:
5560  // A local type, a type with no linkage, an unnamed type or a type
5561  // compounded from any of these types shall not be used as a
5562  // template-argument for a template type-parameter.
5563  //
5564  // C++11 allows these, and even in C++03 we allow them as an extension with
5565  // a warning.
5566  if (LangOpts.CPlusPlus11 || Arg->hasUnnamedOrLocalType()) {
5567  UnnamedLocalNoLinkageFinder Finder(*this, SR);
5568  (void)Finder.Visit(Context.getCanonicalType(Arg));
5569  }
5570 
5571  return false;
5572 }
5573 
5578 };
5579 
5580 /// Determine whether the given template argument is a null pointer
5581 /// value of the appropriate type.
5582 static NullPointerValueKind
5584  QualType ParamType, Expr *Arg,
5585  Decl *Entity = nullptr) {
5586  if (Arg->isValueDependent() || Arg->isTypeDependent())
5587  return NPV_NotNullPointer;
5588 
5589  // dllimport'd entities aren't constant but are available inside of template
5590  // arguments.
5591  if (Entity && Entity->hasAttr<DLLImportAttr>())
5592  return NPV_NotNullPointer;
5593 
5594  if (!S.isCompleteType(Arg->getExprLoc(), ParamType))
5595  llvm_unreachable(
5596  "Incomplete parameter type in isNullPointerValueTemplateArgument!");
5597 
5598  if (!S.getLangOpts().CPlusPlus11)
5599  return NPV_NotNullPointer;
5600 
5601  // Determine whether we have a constant expression.
5603  if (ArgRV.isInvalid())
5604  return NPV_Error;
5605  Arg = ArgRV.get();
5606 
5607  Expr::EvalResult EvalResult;
5609  EvalResult.Diag = &Notes;
5610  if (!Arg->EvaluateAsRValue(EvalResult, S.Context) ||
5611  EvalResult.HasSideEffects) {
5612  SourceLocation DiagLoc = Arg->getExprLoc();
5613 
5614  // If our only note is the usual "invalid subexpression" note, just point
5615  // the caret at its location rather than producing an essentially
5616  // redundant note.
5617  if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
5618  diag::note_invalid_subexpr_in_const_expr) {
5619  DiagLoc = Notes[0].first;
5620  Notes.clear();
5621  }
5622 
5623  S.Diag(DiagLoc, diag::err_template_arg_not_address_constant)
5624  << Arg->getType() << Arg->getSourceRange();
5625  for (unsigned I = 0, N = Notes.size(); I != N; ++I)
5626  S.Diag(Notes[I].first, Notes[I].second);
5627 
5628  S.Diag(Param->getLocation(), diag::note_template_param_here);
5629  return NPV_Error;
5630  }
5631 
5632  // C++11 [temp.arg.nontype]p1:
5633  // - an address constant expression of type std::nullptr_t
5634  if (Arg->getType()->isNullPtrType())
5635  return NPV_NullPointer;
5636 
5637  // - a constant expression that evaluates to a null pointer value (4.10); or
5638  // - a constant expression that evaluates to a null member pointer value
5639  // (4.11); or
5640  if ((EvalResult.Val.isLValue() && !EvalResult.Val.getLValueBase()) ||
5641  (EvalResult.Val.isMemberPointer() &&
5642  !EvalResult.Val.getMemberPointerDecl())) {
5643  // If our expression has an appropriate type, we've succeeded.
5644  bool ObjCLifetimeConversion;
5645  if (S.Context.hasSameUnqualifiedType(Arg->getType(), ParamType) ||
5646  S.IsQualificationConversion(Arg->getType(), ParamType, false,
5647  ObjCLifetimeConversion))
5648  return NPV_NullPointer;
5649 
5650  // The types didn't match, but we know we got a null pointer; complain,
5651  // then recover as if the types were correct.
5652  S.Diag(Arg->getExprLoc(), diag::err_template_arg_wrongtype_null_constant)
5653  << Arg->getType() << ParamType << Arg->getSourceRange();
5654  S.Diag(Param->getLocation(), diag::note_template_param_here);
5655  return NPV_NullPointer;
5656  }
5657 
5658  // If we don't have a null pointer value, but we do have a NULL pointer
5659  // constant, suggest a cast to the appropriate type.
5661  std::string Code = "static_cast<" + ParamType.getAsString() + ">(";
5662  S.Diag(Arg->getExprLoc(), diag::err_template_arg_untyped_null_constant)
5663  << ParamType << FixItHint::CreateInsertion(Arg->getBeginLoc(), Code)
5665  ")");
5666  S.Diag(Param->getLocation(), diag::note_template_param_here);
5667  return NPV_NullPointer;
5668  }
5669 
5670  // FIXME: If we ever want to support general, address-constant expressions
5671  // as non-type template arguments, we should return the ExprResult here to
5672  // be interpreted by the caller.
5673  return NPV_NotNullPointer;
5674 }
5675 
5676 /// Checks whether the given template argument is compatible with its
5677 /// template parameter.
5679  Sema &S, NonTypeTemplateParmDecl *Param, QualType ParamType, Expr *ArgIn,
5680  Expr *Arg, QualType ArgType) {
5681  bool ObjCLifetimeConversion;
5682  if (ParamType->isPointerType() &&
5683  !ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType() &&
5684  S.IsQualificationConversion(ArgType, ParamType, false,
5685  ObjCLifetimeConversion)) {
5686  // For pointer-to-object types, qualification conversions are
5687  // permitted.
5688  } else {
5689  if (const ReferenceType *ParamRef = ParamType->getAs<ReferenceType>()) {
5690  if (!ParamRef->getPointeeType()->isFunctionType()) {
5691  // C++ [temp.arg.nontype]p5b3:
5692  // For a non-type template-parameter of type reference to
5693  // object, no conversions apply. The type referred to by the
5694  // reference may be more cv-qualified than the (otherwise
5695  // identical) type of the template- argument. The
5696  // template-parameter is bound directly to the
5697  // template-argument, which shall be an lvalue.
5698 
5699  // FIXME: Other qualifiers?
5700  unsigned ParamQuals = ParamRef->getPointeeType().getCVRQualifiers();
5701  unsigned ArgQuals = ArgType.getCVRQualifiers();
5702 
5703  if ((ParamQuals | ArgQuals) != ParamQuals) {
5704  S.Diag(Arg->getBeginLoc(),
5705  diag::err_template_arg_ref_bind_ignores_quals)
5706  << ParamType << Arg->getType() << Arg->getSourceRange();
5707  S.Diag(Param->getLocation(), diag::note_template_param_here);
5708  return true;
5709  }
5710  }
5711  }
5712 
5713  // At this point, the template argument refers to an object or
5714  // function with external linkage. We now need to check whether the
5715  // argument and parameter types are compatible.
5716  if (!S.Context.hasSameUnqualifiedType(ArgType,
5717  ParamType.getNonReferenceType())) {
5718  // We can't perform this conversion or binding.
5719  if (ParamType->isReferenceType())
5720  S.Diag(Arg->getBeginLoc(), diag::err_template_arg_no_ref_bind)
5721  << ParamType << ArgIn->getType() << Arg->getSourceRange();
5722  else
5723  S.Diag(Arg->getBeginLoc(), diag::err_template_arg_not_convertible)
5724  << ArgIn->getType() << ParamType << Arg->getSourceRange();
5725  S.Diag(Param->getLocation(), diag::note_template_param_here);
5726  return true;
5727  }
5728  }
5729 
5730  return false;
5731 }
5732 
5733 /// Checks whether the given template argument is the address
5734 /// of an object or function according to C++ [temp.arg.nontype]p1.
5735 static bool
5737  NonTypeTemplateParmDecl *Param,
5738  QualType ParamType,
5739  Expr *ArgIn,
5740  TemplateArgument &Converted) {
5741  bool Invalid = false;
5742  Expr *Arg = ArgIn;
5743  QualType ArgType = Arg->getType();
5744 
5745  bool AddressTaken = false;
5746  SourceLocation AddrOpLoc;
5747  if (S.getLangOpts().MicrosoftExt) {
5748  // Microsoft Visual C++ strips all casts, allows an arbitrary number of
5749  // dereference and address-of operators.
5750  Arg = Arg->IgnoreParenCasts();
5751 
5752  bool ExtWarnMSTemplateArg = false;
5753  UnaryOperatorKind FirstOpKind;
5754  SourceLocation FirstOpLoc;
5755  while (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
5756  UnaryOperatorKind UnOpKind = UnOp->getOpcode();
5757  if (UnOpKind == UO_Deref)
5758  ExtWar