clang  7.0.0svn
SemaTemplate.cpp
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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements semantic analysis for C++ templates.
10 //===----------------------------------------------------------------------===//
11 
12 #include "TreeTransform.h"
13 #include "clang/AST/ASTConsumer.h"
14 #include "clang/AST/ASTContext.h"
15 #include "clang/AST/DeclFriend.h"
16 #include "clang/AST/DeclTemplate.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/TypeVisitor.h"
21 #include "clang/Basic/Builtins.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
26 #include "clang/Sema/Lookup.h"
28 #include "clang/Sema/Scope.h"
30 #include "clang/Sema/Template.h"
32 #include "llvm/ADT/SmallBitVector.h"
33 #include "llvm/ADT/SmallString.h"
34 #include "llvm/ADT/StringExtras.h"
35 
36 #include <iterator>
37 using namespace clang;
38 using namespace sema;
39 
40 // Exported for use by Parser.
43  unsigned N) {
44  if (!N) return SourceRange();
45  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
46 }
47 
48 namespace clang {
49 /// [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.getLocStart(), 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.getLocStart(), diag::err_template_kw_missing)
543  << "" << NameInfo.getName().getAsString()
544  << SourceRange(Less, Greater);
545  return;
546  }
547 
548  // Try to correct the name by looking for templates and C++ named casts.
549  struct TemplateCandidateFilter : CorrectionCandidateCallback {
550  TemplateCandidateFilter() {
551  WantTypeSpecifiers = false;
552  WantExpressionKeywords = false;
553  WantRemainingKeywords = false;
554  WantCXXNamedCasts = true;
555  };
556  bool ValidateCandidate(const TypoCorrection &Candidate) override {
557  if (auto *ND = Candidate.getCorrectionDecl())
558  return isAcceptableTemplateName(ND->getASTContext(), ND, true);
559  return Candidate.isKeyword();
560  }
561  };
562 
563  DeclarationName Name = NameInfo.getName();
564  if (TypoCorrection Corrected =
565  CorrectTypo(NameInfo, LookupKind, S, &SS,
566  llvm::make_unique<TemplateCandidateFilter>(),
567  CTK_ErrorRecovery, LookupCtx)) {
568  auto *ND = Corrected.getFoundDecl();
569  if (ND)
570  ND = isAcceptableTemplateName(Context, ND,
571  /*AllowFunctionTemplates*/ true);
572  if (ND || Corrected.isKeyword()) {
573  if (LookupCtx) {
574  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
575  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
576  Name.getAsString() == CorrectedStr;
577  diagnoseTypo(Corrected,
578  PDiag(diag::err_non_template_in_member_template_id_suggest)
579  << Name << LookupCtx << DroppedSpecifier
580  << SS.getRange(), false);
581  } else {
582  diagnoseTypo(Corrected,
583  PDiag(diag::err_non_template_in_template_id_suggest)
584  << Name, false);
585  }
586  if (Found)
587  Diag(Found->getLocation(),
588  diag::note_non_template_in_template_id_found);
589  return;
590  }
591  }
592 
593  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
594  << Name << SourceRange(Less, Greater);
595  if (Found)
596  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
597 }
598 
599 /// ActOnDependentIdExpression - Handle a dependent id-expression that
600 /// was just parsed. This is only possible with an explicit scope
601 /// specifier naming a dependent type.
604  SourceLocation TemplateKWLoc,
605  const DeclarationNameInfo &NameInfo,
606  bool isAddressOfOperand,
607  const TemplateArgumentListInfo *TemplateArgs) {
608  DeclContext *DC = getFunctionLevelDeclContext();
609 
610  // C++11 [expr.prim.general]p12:
611  // An id-expression that denotes a non-static data member or non-static
612  // member function of a class can only be used:
613  // (...)
614  // - if that id-expression denotes a non-static data member and it
615  // appears in an unevaluated operand.
616  //
617  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
618  // CXXDependentScopeMemberExpr. The former can instantiate to either
619  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
620  // always a MemberExpr.
621  bool MightBeCxx11UnevalField =
622  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
623 
624  // Check if the nested name specifier is an enum type.
625  bool IsEnum = false;
626  if (NestedNameSpecifier *NNS = SS.getScopeRep())
627  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
628 
629  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
630  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
631  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
632 
633  // Since the 'this' expression is synthesized, we don't need to
634  // perform the double-lookup check.
635  NamedDecl *FirstQualifierInScope = nullptr;
636 
638  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
639  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
640  FirstQualifierInScope, NameInfo, TemplateArgs);
641  }
642 
643  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
644 }
645 
648  SourceLocation TemplateKWLoc,
649  const DeclarationNameInfo &NameInfo,
650  const TemplateArgumentListInfo *TemplateArgs) {
652  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
653  TemplateArgs);
654 }
655 
656 
657 /// Determine whether we would be unable to instantiate this template (because
658 /// it either has no definition, or is in the process of being instantiated).
660  NamedDecl *Instantiation,
661  bool InstantiatedFromMember,
662  const NamedDecl *Pattern,
663  const NamedDecl *PatternDef,
665  bool Complain /*= true*/) {
666  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
667  isa<VarDecl>(Instantiation));
668 
669  bool IsEntityBeingDefined = false;
670  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
671  IsEntityBeingDefined = TD->isBeingDefined();
672 
673  if (PatternDef && !IsEntityBeingDefined) {
674  NamedDecl *SuggestedDef = nullptr;
675  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
676  /*OnlyNeedComplete*/false)) {
677  // If we're allowed to diagnose this and recover, do so.
678  bool Recover = Complain && !isSFINAEContext();
679  if (Complain)
680  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
682  return !Recover;
683  }
684  return false;
685  }
686 
687  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
688  return true;
689 
691  QualType InstantiationTy;
692  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
693  InstantiationTy = Context.getTypeDeclType(TD);
694  if (PatternDef) {
695  Diag(PointOfInstantiation,
696  diag::err_template_instantiate_within_definition)
697  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
698  << InstantiationTy;
699  // Not much point in noting the template declaration here, since
700  // we're lexically inside it.
701  Instantiation->setInvalidDecl();
702  } else if (InstantiatedFromMember) {
703  if (isa<FunctionDecl>(Instantiation)) {
704  Diag(PointOfInstantiation,
705  diag::err_explicit_instantiation_undefined_member)
706  << /*member function*/ 1 << Instantiation->getDeclName()
707  << Instantiation->getDeclContext();
708  Note = diag::note_explicit_instantiation_here;
709  } else {
710  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
711  Diag(PointOfInstantiation,
712  diag::err_implicit_instantiate_member_undefined)
713  << InstantiationTy;
714  Note = diag::note_member_declared_at;
715  }
716  } else {
717  if (isa<FunctionDecl>(Instantiation)) {
718  Diag(PointOfInstantiation,
719  diag::err_explicit_instantiation_undefined_func_template)
720  << Pattern;
721  Note = diag::note_explicit_instantiation_here;
722  } else if (isa<TagDecl>(Instantiation)) {
723  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
724  << (TSK != TSK_ImplicitInstantiation)
725  << InstantiationTy;
726  Note = diag::note_template_decl_here;
727  } else {
728  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
729  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
730  Diag(PointOfInstantiation,
731  diag::err_explicit_instantiation_undefined_var_template)
732  << Instantiation;
733  Instantiation->setInvalidDecl();
734  } else
735  Diag(PointOfInstantiation,
736  diag::err_explicit_instantiation_undefined_member)
737  << /*static data member*/ 2 << Instantiation->getDeclName()
738  << Instantiation->getDeclContext();
739  Note = diag::note_explicit_instantiation_here;
740  }
741  }
742  if (Note) // Diagnostics were emitted.
743  Diag(Pattern->getLocation(), Note.getValue());
744 
745  // In general, Instantiation isn't marked invalid to get more than one
746  // error for multiple undefined instantiations. But the code that does
747  // explicit declaration -> explicit definition conversion can't handle
748  // invalid declarations, so mark as invalid in that case.
750  Instantiation->setInvalidDecl();
751  return true;
752 }
753 
754 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
755 /// that the template parameter 'PrevDecl' is being shadowed by a new
756 /// declaration at location Loc. Returns true to indicate that this is
757 /// an error, and false otherwise.
759  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
760 
761  // Microsoft Visual C++ permits template parameters to be shadowed.
762  if (getLangOpts().MicrosoftExt)
763  return;
764 
765  // C++ [temp.local]p4:
766  // A template-parameter shall not be redeclared within its
767  // scope (including nested scopes).
768  Diag(Loc, diag::err_template_param_shadow)
769  << cast<NamedDecl>(PrevDecl)->getDeclName();
770  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
771 }
772 
773 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
774 /// the parameter D to reference the templated declaration and return a pointer
775 /// to the template declaration. Otherwise, do nothing to D and return null.
777  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
778  D = Temp->getTemplatedDecl();
779  return Temp;
780  }
781  return nullptr;
782 }
783 
785  SourceLocation EllipsisLoc) const {
786  assert(Kind == Template &&
787  "Only template template arguments can be pack expansions here");
788  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
789  "Template template argument pack expansion without packs");
790  ParsedTemplateArgument Result(*this);
791  Result.EllipsisLoc = EllipsisLoc;
792  return Result;
793 }
794 
796  const ParsedTemplateArgument &Arg) {
797 
798  switch (Arg.getKind()) {
800  TypeSourceInfo *DI;
801  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
802  if (!DI)
803  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
804  return TemplateArgumentLoc(TemplateArgument(T), DI);
805  }
806 
808  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
810  }
811 
813  TemplateName Template = Arg.getAsTemplate().get();
814  TemplateArgument TArg;
815  if (Arg.getEllipsisLoc().isValid())
816  TArg = TemplateArgument(Template, Optional<unsigned int>());
817  else
818  TArg = Template;
819  return TemplateArgumentLoc(TArg,
821  SemaRef.Context),
822  Arg.getLocation(),
823  Arg.getEllipsisLoc());
824  }
825  }
826 
827  llvm_unreachable("Unhandled parsed template argument");
828 }
829 
830 /// Translates template arguments as provided by the parser
831 /// into template arguments used by semantic analysis.
833  TemplateArgumentListInfo &TemplateArgs) {
834  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
835  TemplateArgs.addArgument(translateTemplateArgument(*this,
836  TemplateArgsIn[I]));
837 }
838 
840  SourceLocation Loc,
841  IdentifierInfo *Name) {
842  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
844  if (PrevDecl && PrevDecl->isTemplateParameter())
845  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
846 }
847 
848 /// Convert a parsed type into a parsed template argument. This is mostly
849 /// trivial, except that we may have parsed a C++17 deduced class template
850 /// specialization type, in which case we should form a template template
851 /// argument instead of a type template argument.
853  TypeSourceInfo *TInfo;
854  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
855  if (T.isNull())
856  return ParsedTemplateArgument();
857  assert(TInfo && "template argument with no location");
858 
859  // If we might have formed a deduced template specialization type, convert
860  // it to a template template argument.
861  if (getLangOpts().CPlusPlus17) {
862  TypeLoc TL = TInfo->getTypeLoc();
863  SourceLocation EllipsisLoc;
864  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
865  EllipsisLoc = PET.getEllipsisLoc();
866  TL = PET.getPatternLoc();
867  }
868 
869  CXXScopeSpec SS;
870  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
871  SS.Adopt(ET.getQualifierLoc());
872  TL = ET.getNamedTypeLoc();
873  }
874 
875  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
876  TemplateName Name = DTST.getTypePtr()->getTemplateName();
877  if (SS.isSet())
878  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
879  /*HasTemplateKeyword*/ false,
880  Name.getAsTemplateDecl());
881  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
882  DTST.getTemplateNameLoc());
883  if (EllipsisLoc.isValid())
884  Result = Result.getTemplatePackExpansion(EllipsisLoc);
885  return Result;
886  }
887  }
888 
889  // This is a normal type template argument. Note, if the type template
890  // argument is an injected-class-name for a template, it has a dual nature
891  // and can be used as either a type or a template. We handle that in
892  // convertTypeTemplateArgumentToTemplate.
894  ParsedType.get().getAsOpaquePtr(),
895  TInfo->getTypeLoc().getLocStart());
896 }
897 
898 /// ActOnTypeParameter - Called when a C++ template type parameter
899 /// (e.g., "typename T") has been parsed. Typename specifies whether
900 /// the keyword "typename" was used to declare the type parameter
901 /// (otherwise, "class" was used), and KeyLoc is the location of the
902 /// "class" or "typename" keyword. ParamName is the name of the
903 /// parameter (NULL indicates an unnamed template parameter) and
904 /// ParamNameLoc is the location of the parameter name (if any).
905 /// If the type parameter has a default argument, it will be added
906 /// later via ActOnTypeParameterDefault.
908  SourceLocation EllipsisLoc,
909  SourceLocation KeyLoc,
910  IdentifierInfo *ParamName,
911  SourceLocation ParamNameLoc,
912  unsigned Depth, unsigned Position,
913  SourceLocation EqualLoc,
914  ParsedType DefaultArg) {
915  assert(S->isTemplateParamScope() &&
916  "Template type parameter not in template parameter scope!");
917 
918  SourceLocation Loc = ParamNameLoc;
919  if (!ParamName)
920  Loc = KeyLoc;
921 
922  bool IsParameterPack = EllipsisLoc.isValid();
923  TemplateTypeParmDecl *Param
925  KeyLoc, Loc, Depth, Position, ParamName,
926  Typename, IsParameterPack);
927  Param->setAccess(AS_public);
928 
929  if (ParamName) {
930  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
931 
932  // Add the template parameter into the current scope.
933  S->AddDecl(Param);
934  IdResolver.AddDecl(Param);
935  }
936 
937  // C++0x [temp.param]p9:
938  // A default template-argument may be specified for any kind of
939  // template-parameter that is not a template parameter pack.
940  if (DefaultArg && IsParameterPack) {
941  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
942  DefaultArg = nullptr;
943  }
944 
945  // Handle the default argument, if provided.
946  if (DefaultArg) {
947  TypeSourceInfo *DefaultTInfo;
948  GetTypeFromParser(DefaultArg, &DefaultTInfo);
949 
950  assert(DefaultTInfo && "expected source information for type");
951 
952  // Check for unexpanded parameter packs.
953  if (DiagnoseUnexpandedParameterPack(Loc, DefaultTInfo,
954  UPPC_DefaultArgument))
955  return Param;
956 
957  // Check the template argument itself.
958  if (CheckTemplateArgument(Param, DefaultTInfo)) {
959  Param->setInvalidDecl();
960  return Param;
961  }
962 
963  Param->setDefaultArgument(DefaultTInfo);
964  }
965 
966  return Param;
967 }
968 
969 /// Check that the type of a non-type template parameter is
970 /// well-formed.
971 ///
972 /// \returns the (possibly-promoted) parameter type if valid;
973 /// otherwise, produces a diagnostic and returns a NULL type.
975  SourceLocation Loc) {
976  if (TSI->getType()->isUndeducedType()) {
977  // C++1z [temp.dep.expr]p3:
978  // An id-expression is type-dependent if it contains
979  // - an identifier associated by name lookup with a non-type
980  // template-parameter declared with a type that contains a
981  // placeholder type (7.1.7.4),
982  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
983  }
984 
985  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
986 }
987 
989  SourceLocation Loc) {
990  // We don't allow variably-modified types as the type of non-type template
991  // parameters.
992  if (T->isVariablyModifiedType()) {
993  Diag(Loc, diag::err_variably_modified_nontype_template_param)
994  << T;
995  return QualType();
996  }
997 
998  // C++ [temp.param]p4:
999  //
1000  // A non-type template-parameter shall have one of the following
1001  // (optionally cv-qualified) types:
1002  //
1003  // -- integral or enumeration type,
1004  if (T->isIntegralOrEnumerationType() ||
1005  // -- pointer to object or pointer to function,
1006  T->isPointerType() ||
1007  // -- reference to object or reference to function,
1008  T->isReferenceType() ||
1009  // -- pointer to member,
1010  T->isMemberPointerType() ||
1011  // -- std::nullptr_t.
1012  T->isNullPtrType() ||
1013  // If T is a dependent type, we can't do the check now, so we
1014  // assume that it is well-formed.
1015  T->isDependentType() ||
1016  // Allow use of auto in template parameter declarations.
1017  T->isUndeducedType()) {
1018  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1019  // are ignored when determining its type.
1020  return T.getUnqualifiedType();
1021  }
1022 
1023  // C++ [temp.param]p8:
1024  //
1025  // A non-type template-parameter of type "array of T" or
1026  // "function returning T" is adjusted to be of type "pointer to
1027  // T" or "pointer to function returning T", respectively.
1028  else if (T->isArrayType() || T->isFunctionType())
1029  return Context.getDecayedType(T);
1030 
1031  Diag(Loc, diag::err_template_nontype_parm_bad_type)
1032  << T;
1033 
1034  return QualType();
1035 }
1036 
1038  unsigned Depth,
1039  unsigned Position,
1040  SourceLocation EqualLoc,
1041  Expr *Default) {
1042  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1043 
1044  // Check that we have valid decl-specifiers specified.
1045  auto CheckValidDeclSpecifiers = [this, &D] {
1046  // C++ [temp.param]
1047  // p1
1048  // template-parameter:
1049  // ...
1050  // parameter-declaration
1051  // p2
1052  // ... A storage class shall not be specified in a template-parameter
1053  // declaration.
1054  // [dcl.typedef]p1:
1055  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1056  // of a parameter-declaration
1057  const DeclSpec &DS = D.getDeclSpec();
1058  auto EmitDiag = [this](SourceLocation Loc) {
1059  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1060  << FixItHint::CreateRemoval(Loc);
1061  };
1063  EmitDiag(DS.getStorageClassSpecLoc());
1064 
1066  EmitDiag(DS.getThreadStorageClassSpecLoc());
1067 
1068  // [dcl.inline]p1:
1069  // The inline specifier can be applied only to the declaration or
1070  // definition of a variable or function.
1071 
1072  if (DS.isInlineSpecified())
1073  EmitDiag(DS.getInlineSpecLoc());
1074 
1075  // [dcl.constexpr]p1:
1076  // The constexpr specifier shall be applied only to the definition of a
1077  // variable or variable template or the declaration of a function or
1078  // function template.
1079 
1080  if (DS.isConstexprSpecified())
1081  EmitDiag(DS.getConstexprSpecLoc());
1082 
1083  // [dcl.fct.spec]p1:
1084  // Function-specifiers can be used only in function declarations.
1085 
1086  if (DS.isVirtualSpecified())
1087  EmitDiag(DS.getVirtualSpecLoc());
1088 
1089  if (DS.isExplicitSpecified())
1090  EmitDiag(DS.getExplicitSpecLoc());
1091 
1092  if (DS.isNoreturnSpecified())
1093  EmitDiag(DS.getNoreturnSpecLoc());
1094  };
1095 
1096  CheckValidDeclSpecifiers();
1097 
1098  if (TInfo->getType()->isUndeducedType()) {
1099  Diag(D.getIdentifierLoc(),
1100  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1101  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1102  }
1103 
1104  assert(S->isTemplateParamScope() &&
1105  "Non-type template parameter not in template parameter scope!");
1106  bool Invalid = false;
1107 
1108  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1109  if (T.isNull()) {
1110  T = Context.IntTy; // Recover with an 'int' type.
1111  Invalid = true;
1112  }
1113 
1114  IdentifierInfo *ParamName = D.getIdentifier();
1115  bool IsParameterPack = D.hasEllipsis();
1118  D.getLocStart(),
1119  D.getIdentifierLoc(),
1120  Depth, Position, ParamName, T,
1121  IsParameterPack, TInfo);
1122  Param->setAccess(AS_public);
1123 
1124  if (Invalid)
1125  Param->setInvalidDecl();
1126 
1127  if (ParamName) {
1129  ParamName);
1130 
1131  // Add the template parameter into the current scope.
1132  S->AddDecl(Param);
1133  IdResolver.AddDecl(Param);
1134  }
1135 
1136  // C++0x [temp.param]p9:
1137  // A default template-argument may be specified for any kind of
1138  // template-parameter that is not a template parameter pack.
1139  if (Default && IsParameterPack) {
1140  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1141  Default = nullptr;
1142  }
1143 
1144  // Check the well-formedness of the default template argument, if provided.
1145  if (Default) {
1146  // Check for unexpanded parameter packs.
1147  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1148  return Param;
1149 
1150  TemplateArgument Converted;
1151  ExprResult DefaultRes =
1152  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1153  if (DefaultRes.isInvalid()) {
1154  Param->setInvalidDecl();
1155  return Param;
1156  }
1157  Default = DefaultRes.get();
1158 
1159  Param->setDefaultArgument(Default);
1160  }
1161 
1162  return Param;
1163 }
1164 
1165 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1166 /// parameter (e.g. T in template <template <typename> class T> class array)
1167 /// has been parsed. S is the current scope.
1169  SourceLocation TmpLoc,
1170  TemplateParameterList *Params,
1171  SourceLocation EllipsisLoc,
1172  IdentifierInfo *Name,
1173  SourceLocation NameLoc,
1174  unsigned Depth,
1175  unsigned Position,
1176  SourceLocation EqualLoc,
1177  ParsedTemplateArgument Default) {
1178  assert(S->isTemplateParamScope() &&
1179  "Template template parameter not in template parameter scope!");
1180 
1181  // Construct the parameter object.
1182  bool IsParameterPack = EllipsisLoc.isValid();
1183  TemplateTemplateParmDecl *Param =
1185  NameLoc.isInvalid()? TmpLoc : NameLoc,
1186  Depth, Position, IsParameterPack,
1187  Name, Params);
1188  Param->setAccess(AS_public);
1189 
1190  // If the template template parameter has a name, then link the identifier
1191  // into the scope and lookup mechanisms.
1192  if (Name) {
1193  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1194 
1195  S->AddDecl(Param);
1196  IdResolver.AddDecl(Param);
1197  }
1198 
1199  if (Params->size() == 0) {
1200  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1201  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1202  Param->setInvalidDecl();
1203  }
1204 
1205  // C++0x [temp.param]p9:
1206  // A default template-argument may be specified for any kind of
1207  // template-parameter that is not a template parameter pack.
1208  if (IsParameterPack && !Default.isInvalid()) {
1209  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1210  Default = ParsedTemplateArgument();
1211  }
1212 
1213  if (!Default.isInvalid()) {
1214  // Check only that we have a template template argument. We don't want to
1215  // try to check well-formedness now, because our template template parameter
1216  // might have dependent types in its template parameters, which we wouldn't
1217  // be able to match now.
1218  //
1219  // If none of the template template parameter's template arguments mention
1220  // other template parameters, we could actually perform more checking here.
1221  // However, it isn't worth doing.
1222  TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
1223  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1224  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1225  << DefaultArg.getSourceRange();
1226  return Param;
1227  }
1228 
1229  // Check for unexpanded parameter packs.
1230  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1231  DefaultArg.getArgument().getAsTemplate(),
1232  UPPC_DefaultArgument))
1233  return Param;
1234 
1235  Param->setDefaultArgument(Context, DefaultArg);
1236  }
1237 
1238  return Param;
1239 }
1240 
1241 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1242 /// constrained by RequiresClause, that contains the template parameters in
1243 /// Params.
1246  SourceLocation ExportLoc,
1247  SourceLocation TemplateLoc,
1248  SourceLocation LAngleLoc,
1249  ArrayRef<NamedDecl *> Params,
1250  SourceLocation RAngleLoc,
1251  Expr *RequiresClause) {
1252  if (ExportLoc.isValid())
1253  Diag(ExportLoc, diag::warn_template_export_unsupported);
1254 
1256  Context, TemplateLoc, LAngleLoc,
1257  llvm::makeArrayRef(Params.data(), Params.size()),
1258  RAngleLoc, RequiresClause);
1259 }
1260 
1261 static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
1262  if (SS.isSet())
1264 }
1265 
1267  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1268  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1269  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1270  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1271  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1272  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1273  assert(TemplateParams && TemplateParams->size() > 0 &&
1274  "No template parameters");
1275  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1276  bool Invalid = false;
1277 
1278  // Check that we can declare a template here.
1279  if (CheckTemplateDeclScope(S, TemplateParams))
1280  return true;
1281 
1283  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1284 
1285  // There is no such thing as an unnamed class template.
1286  if (!Name) {
1287  Diag(KWLoc, diag::err_template_unnamed_class);
1288  return true;
1289  }
1290 
1291  // Find any previous declaration with this name. For a friend with no
1292  // scope explicitly specified, we only look for tag declarations (per
1293  // C++11 [basic.lookup.elab]p2).
1294  DeclContext *SemanticContext;
1295  LookupResult Previous(*this, Name, NameLoc,
1296  (SS.isEmpty() && TUK == TUK_Friend)
1297  ? LookupTagName : LookupOrdinaryName,
1298  forRedeclarationInCurContext());
1299  if (SS.isNotEmpty() && !SS.isInvalid()) {
1300  SemanticContext = computeDeclContext(SS, true);
1301  if (!SemanticContext) {
1302  // FIXME: Horrible, horrible hack! We can't currently represent this
1303  // in the AST, and historically we have just ignored such friend
1304  // class templates, so don't complain here.
1305  Diag(NameLoc, TUK == TUK_Friend
1306  ? diag::warn_template_qualified_friend_ignored
1307  : diag::err_template_qualified_declarator_no_match)
1308  << SS.getScopeRep() << SS.getRange();
1309  return TUK != TUK_Friend;
1310  }
1311 
1312  if (RequireCompleteDeclContext(SS, SemanticContext))
1313  return true;
1314 
1315  // If we're adding a template to a dependent context, we may need to
1316  // rebuilding some of the types used within the template parameter list,
1317  // now that we know what the current instantiation is.
1318  if (SemanticContext->isDependentContext()) {
1319  ContextRAII SavedContext(*this, SemanticContext);
1320  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1321  Invalid = true;
1322  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1323  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1324 
1325  LookupQualifiedName(Previous, SemanticContext);
1326  } else {
1327  SemanticContext = CurContext;
1328 
1329  // C++14 [class.mem]p14:
1330  // If T is the name of a class, then each of the following shall have a
1331  // name different from T:
1332  // -- every member template of class T
1333  if (TUK != TUK_Friend &&
1334  DiagnoseClassNameShadow(SemanticContext,
1335  DeclarationNameInfo(Name, NameLoc)))
1336  return true;
1337 
1338  LookupName(Previous, S);
1339  }
1340 
1341  if (Previous.isAmbiguous())
1342  return true;
1343 
1344  NamedDecl *PrevDecl = nullptr;
1345  if (Previous.begin() != Previous.end())
1346  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1347 
1348  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1349  // Maybe we will complain about the shadowed template parameter.
1350  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1351  // Just pretend that we didn't see the previous declaration.
1352  PrevDecl = nullptr;
1353  }
1354 
1355  // If there is a previous declaration with the same name, check
1356  // whether this is a valid redeclaration.
1357  ClassTemplateDecl *PrevClassTemplate =
1358  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1359 
1360  // We may have found the injected-class-name of a class template,
1361  // class template partial specialization, or class template specialization.
1362  // In these cases, grab the template that is being defined or specialized.
1363  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1364  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1365  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1366  PrevClassTemplate
1367  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1368  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1369  PrevClassTemplate
1370  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1371  ->getSpecializedTemplate();
1372  }
1373  }
1374 
1375  if (TUK == TUK_Friend) {
1376  // C++ [namespace.memdef]p3:
1377  // [...] When looking for a prior declaration of a class or a function
1378  // declared as a friend, and when the name of the friend class or
1379  // function is neither a qualified name nor a template-id, scopes outside
1380  // the innermost enclosing namespace scope are not considered.
1381  if (!SS.isSet()) {
1382  DeclContext *OutermostContext = CurContext;
1383  while (!OutermostContext->isFileContext())
1384  OutermostContext = OutermostContext->getLookupParent();
1385 
1386  if (PrevDecl &&
1387  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1388  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1389  SemanticContext = PrevDecl->getDeclContext();
1390  } else {
1391  // Declarations in outer scopes don't matter. However, the outermost
1392  // context we computed is the semantic context for our new
1393  // declaration.
1394  PrevDecl = PrevClassTemplate = nullptr;
1395  SemanticContext = OutermostContext;
1396 
1397  // Check that the chosen semantic context doesn't already contain a
1398  // declaration of this name as a non-tag type.
1399  Previous.clear(LookupOrdinaryName);
1400  DeclContext *LookupContext = SemanticContext;
1401  while (LookupContext->isTransparentContext())
1402  LookupContext = LookupContext->getLookupParent();
1403  LookupQualifiedName(Previous, LookupContext);
1404 
1405  if (Previous.isAmbiguous())
1406  return true;
1407 
1408  if (Previous.begin() != Previous.end())
1409  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1410  }
1411  }
1412  } else if (PrevDecl &&
1413  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1414  S, SS.isValid()))
1415  PrevDecl = PrevClassTemplate = nullptr;
1416 
1417  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1418  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1419  if (SS.isEmpty() &&
1420  !(PrevClassTemplate &&
1421  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1422  SemanticContext->getRedeclContext()))) {
1423  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1424  Diag(Shadow->getTargetDecl()->getLocation(),
1425  diag::note_using_decl_target);
1426  Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1427  // Recover by ignoring the old declaration.
1428  PrevDecl = PrevClassTemplate = nullptr;
1429  }
1430  }
1431 
1432  // TODO Memory management; associated constraints are not always stored.
1433  Expr *const CurAC = formAssociatedConstraints(TemplateParams, nullptr);
1434 
1435  if (PrevClassTemplate) {
1436  // Ensure that the template parameter lists are compatible. Skip this check
1437  // for a friend in a dependent context: the template parameter list itself
1438  // could be dependent.
1439  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1440  !TemplateParameterListsAreEqual(TemplateParams,
1441  PrevClassTemplate->getTemplateParameters(),
1442  /*Complain=*/true,
1443  TPL_TemplateMatch))
1444  return true;
1445 
1446  // Check for matching associated constraints on redeclarations.
1447  const Expr *const PrevAC = PrevClassTemplate->getAssociatedConstraints();
1448  const bool RedeclACMismatch = [&] {
1449  if (!(CurAC || PrevAC))
1450  return false; // Nothing to check; no mismatch.
1451  if (CurAC && PrevAC) {
1452  llvm::FoldingSetNodeID CurACInfo, PrevACInfo;
1453  CurAC->Profile(CurACInfo, Context, /*Canonical=*/true);
1454  PrevAC->Profile(PrevACInfo, Context, /*Canonical=*/true);
1455  if (CurACInfo == PrevACInfo)
1456  return false; // All good; no mismatch.
1457  }
1458  return true;
1459  }();
1460 
1461  if (RedeclACMismatch) {
1462  Diag(CurAC ? CurAC->getLocStart() : NameLoc,
1463  diag::err_template_different_associated_constraints);
1464  Diag(PrevAC ? PrevAC->getLocStart() : PrevClassTemplate->getLocation(),
1465  diag::note_template_prev_declaration) << /*declaration*/0;
1466  return true;
1467  }
1468 
1469  // C++ [temp.class]p4:
1470  // In a redeclaration, partial specialization, explicit
1471  // specialization or explicit instantiation of a class template,
1472  // the class-key shall agree in kind with the original class
1473  // template declaration (7.1.5.3).
1474  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1475  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1476  TUK == TUK_Definition, KWLoc, Name)) {
1477  Diag(KWLoc, diag::err_use_with_wrong_tag)
1478  << Name
1479  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1480  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1481  Kind = PrevRecordDecl->getTagKind();
1482  }
1483 
1484  // Check for redefinition of this class template.
1485  if (TUK == TUK_Definition) {
1486  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1487  // If we have a prior definition that is not visible, treat this as
1488  // simply making that previous definition visible.
1489  NamedDecl *Hidden = nullptr;
1490  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1491  SkipBody->ShouldSkip = true;
1492  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1493  assert(Tmpl && "original definition of a class template is not a "
1494  "class template?");
1495  makeMergedDefinitionVisible(Hidden);
1496  makeMergedDefinitionVisible(Tmpl);
1497  return Def;
1498  }
1499 
1500  Diag(NameLoc, diag::err_redefinition) << Name;
1501  Diag(Def->getLocation(), diag::note_previous_definition);
1502  // FIXME: Would it make sense to try to "forget" the previous
1503  // definition, as part of error recovery?
1504  return true;
1505  }
1506  }
1507  } else if (PrevDecl) {
1508  // C++ [temp]p5:
1509  // A class template shall not have the same name as any other
1510  // template, class, function, object, enumeration, enumerator,
1511  // namespace, or type in the same scope (3.3), except as specified
1512  // in (14.5.4).
1513  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1514  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1515  return true;
1516  }
1517 
1518  // Check the template parameter list of this declaration, possibly
1519  // merging in the template parameter list from the previous class
1520  // template declaration. Skip this check for a friend in a dependent
1521  // context, because the template parameter list might be dependent.
1522  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1523  CheckTemplateParameterList(
1524  TemplateParams,
1525  PrevClassTemplate ? PrevClassTemplate->getTemplateParameters()
1526  : nullptr,
1527  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1528  SemanticContext->isDependentContext())
1529  ? TPC_ClassTemplateMember
1530  : TUK == TUK_Friend ? TPC_FriendClassTemplate
1531  : TPC_ClassTemplate))
1532  Invalid = true;
1533 
1534  if (SS.isSet()) {
1535  // If the name of the template was qualified, we must be defining the
1536  // template out-of-line.
1537  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1538  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1539  : diag::err_member_decl_does_not_match)
1540  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1541  Invalid = true;
1542  }
1543  }
1544 
1545  // If this is a templated friend in a dependent context we should not put it
1546  // on the redecl chain. In some cases, the templated friend can be the most
1547  // recent declaration tricking the template instantiator to make substitutions
1548  // there.
1549  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1550  bool ShouldAddRedecl
1551  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1552 
1553  CXXRecordDecl *NewClass =
1554  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1555  PrevClassTemplate && ShouldAddRedecl ?
1556  PrevClassTemplate->getTemplatedDecl() : nullptr,
1557  /*DelayTypeCreation=*/true);
1558  SetNestedNameSpecifier(NewClass, SS);
1559  if (NumOuterTemplateParamLists > 0)
1561  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1562  NumOuterTemplateParamLists));
1563 
1564  // Add alignment attributes if necessary; these attributes are checked when
1565  // the ASTContext lays out the structure.
1566  if (TUK == TUK_Definition) {
1567  AddAlignmentAttributesForRecord(NewClass);
1568  AddMsStructLayoutForRecord(NewClass);
1569  }
1570 
1571  // Attach the associated constraints when the declaration will not be part of
1572  // a decl chain.
1573  Expr *const ACtoAttach =
1574  PrevClassTemplate && ShouldAddRedecl ? nullptr : CurAC;
1575 
1576  ClassTemplateDecl *NewTemplate
1577  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1578  DeclarationName(Name), TemplateParams,
1579  NewClass, ACtoAttach);
1580 
1581  if (ShouldAddRedecl)
1582  NewTemplate->setPreviousDecl(PrevClassTemplate);
1583 
1584  NewClass->setDescribedClassTemplate(NewTemplate);
1585 
1586  if (ModulePrivateLoc.isValid())
1587  NewTemplate->setModulePrivate();
1588 
1589  // Build the type for the class template declaration now.
1590  QualType T = NewTemplate->getInjectedClassNameSpecialization();
1591  T = Context.getInjectedClassNameType(NewClass, T);
1592  assert(T->isDependentType() && "Class template type is not dependent?");
1593  (void)T;
1594 
1595  // If we are providing an explicit specialization of a member that is a
1596  // class template, make a note of that.
1597  if (PrevClassTemplate &&
1598  PrevClassTemplate->getInstantiatedFromMemberTemplate())
1599  PrevClassTemplate->setMemberSpecialization();
1600 
1601  // Set the access specifier.
1602  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1603  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1604 
1605  // Set the lexical context of these templates
1606  NewClass->setLexicalDeclContext(CurContext);
1607  NewTemplate->setLexicalDeclContext(CurContext);
1608 
1609  if (TUK == TUK_Definition)
1610  NewClass->startDefinition();
1611 
1612  ProcessDeclAttributeList(S, NewClass, Attr);
1613 
1614  if (PrevClassTemplate)
1615  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1616 
1617  AddPushedVisibilityAttribute(NewClass);
1618 
1619  if (TUK != TUK_Friend) {
1620  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
1621  Scope *Outer = S;
1622  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
1623  Outer = Outer->getParent();
1624  PushOnScopeChains(NewTemplate, Outer);
1625  } else {
1626  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1627  NewTemplate->setAccess(PrevClassTemplate->getAccess());
1628  NewClass->setAccess(PrevClassTemplate->getAccess());
1629  }
1630 
1631  NewTemplate->setObjectOfFriendDecl();
1632 
1633  // Friend templates are visible in fairly strange ways.
1634  if (!CurContext->isDependentContext()) {
1635  DeclContext *DC = SemanticContext->getRedeclContext();
1636  DC->makeDeclVisibleInContext(NewTemplate);
1637  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1638  PushOnScopeChains(NewTemplate, EnclosingScope,
1639  /* AddToContext = */ false);
1640  }
1641 
1642  FriendDecl *Friend = FriendDecl::Create(
1643  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
1644  Friend->setAccess(AS_public);
1645  CurContext->addDecl(Friend);
1646  }
1647 
1648  if (PrevClassTemplate)
1649  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
1650 
1651  if (Invalid) {
1652  NewTemplate->setInvalidDecl();
1653  NewClass->setInvalidDecl();
1654  }
1655 
1656  ActOnDocumentableDecl(NewTemplate);
1657 
1658  return NewTemplate;
1659 }
1660 
1661 namespace {
1662 /// Transform to convert portions of a constructor declaration into the
1663 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
1664 struct ConvertConstructorToDeductionGuideTransform {
1665  ConvertConstructorToDeductionGuideTransform(Sema &S,
1666  ClassTemplateDecl *Template)
1667  : SemaRef(S), Template(Template) {}
1668 
1669  Sema &SemaRef;
1670  ClassTemplateDecl *Template;
1671 
1672  DeclContext *DC = Template->getDeclContext();
1673  CXXRecordDecl *Primary = Template->getTemplatedDecl();
1674  DeclarationName DeductionGuideName =
1676 
1677  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
1678 
1679  // Index adjustment to apply to convert depth-1 template parameters into
1680  // depth-0 template parameters.
1681  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
1682 
1683  /// Transform a constructor declaration into a deduction guide.
1684  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
1685  CXXConstructorDecl *CD) {
1687 
1688  LocalInstantiationScope Scope(SemaRef);
1689 
1690  // C++ [over.match.class.deduct]p1:
1691  // -- For each constructor of the class template designated by the
1692  // template-name, a function template with the following properties:
1693 
1694  // -- The template parameters are the template parameters of the class
1695  // template followed by the template parameters (including default
1696  // template arguments) of the constructor, if any.
1697  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
1698  if (FTD) {
1699  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
1700  SmallVector<NamedDecl *, 16> AllParams;
1701  AllParams.reserve(TemplateParams->size() + InnerParams->size());
1702  AllParams.insert(AllParams.begin(),
1703  TemplateParams->begin(), TemplateParams->end());
1704  SubstArgs.reserve(InnerParams->size());
1705 
1706  // Later template parameters could refer to earlier ones, so build up
1707  // a list of substituted template arguments as we go.
1708  for (NamedDecl *Param : *InnerParams) {
1710  Args.addOuterTemplateArguments(SubstArgs);
1711  Args.addOuterRetainedLevel();
1712  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
1713  if (!NewParam)
1714  return nullptr;
1715  AllParams.push_back(NewParam);
1716  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
1717  SemaRef.Context.getInjectedTemplateArg(NewParam)));
1718  }
1719  TemplateParams = TemplateParameterList::Create(
1720  SemaRef.Context, InnerParams->getTemplateLoc(),
1721  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
1722  /*FIXME: RequiresClause*/ nullptr);
1723  }
1724 
1725  // If we built a new template-parameter-list, track that we need to
1726  // substitute references to the old parameters into references to the
1727  // new ones.
1729  if (FTD) {
1730  Args.addOuterTemplateArguments(SubstArgs);
1731  Args.addOuterRetainedLevel();
1732  }
1733 
1736  assert(FPTL && "no prototype for constructor declaration");
1737 
1738  // Transform the type of the function, adjusting the return type and
1739  // replacing references to the old parameters with references to the
1740  // new ones.
1741  TypeLocBuilder TLB;
1743  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args);
1744  if (NewType.isNull())
1745  return nullptr;
1746  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
1747 
1748  return buildDeductionGuide(TemplateParams, CD->isExplicit(), NewTInfo,
1749  CD->getLocStart(), CD->getLocation(),
1750  CD->getLocEnd());
1751  }
1752 
1753  /// Build a deduction guide with the specified parameter types.
1754  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
1755  SourceLocation Loc = Template->getLocation();
1756 
1757  // Build the requested type.
1759  EPI.HasTrailingReturn = true;
1760  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
1761  DeductionGuideName, EPI);
1762  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
1763 
1764  FunctionProtoTypeLoc FPTL =
1766 
1767  // Build the parameters, needed during deduction / substitution.
1769  for (auto T : ParamTypes) {
1770  ParmVarDecl *NewParam = ParmVarDecl::Create(
1771  SemaRef.Context, DC, Loc, Loc, nullptr, T,
1772  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
1773  NewParam->setScopeInfo(0, Params.size());
1774  FPTL.setParam(Params.size(), NewParam);
1775  Params.push_back(NewParam);
1776  }
1777 
1778  return buildDeductionGuide(Template->getTemplateParameters(), false, TSI,
1779  Loc, Loc, Loc);
1780  }
1781 
1782 private:
1783  /// Transform a constructor template parameter into a deduction guide template
1784  /// parameter, rebuilding any internal references to earlier parameters and
1785  /// renumbering as we go.
1786  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
1788  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
1789  // TemplateTypeParmDecl's index cannot be changed after creation, so
1790  // substitute it directly.
1791  auto *NewTTP = TemplateTypeParmDecl::Create(
1792  SemaRef.Context, DC, TTP->getLocStart(), TTP->getLocation(),
1793  /*Depth*/0, Depth1IndexAdjustment + TTP->getIndex(),
1794  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
1795  TTP->isParameterPack());
1796  if (TTP->hasDefaultArgument()) {
1797  TypeSourceInfo *InstantiatedDefaultArg =
1798  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
1799  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
1800  if (InstantiatedDefaultArg)
1801  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
1802  }
1803  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
1804  NewTTP);
1805  return NewTTP;
1806  }
1807 
1808  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
1809  return transformTemplateParameterImpl(TTP, Args);
1810 
1811  return transformTemplateParameterImpl(
1812  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
1813  }
1814  template<typename TemplateParmDecl>
1815  TemplateParmDecl *
1816  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
1818  // Ask the template instantiator to do the heavy lifting for us, then adjust
1819  // the index of the parameter once it's done.
1820  auto *NewParam =
1821  cast_or_null<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
1822  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
1823  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
1824  return NewParam;
1825  }
1826 
1827  QualType transformFunctionProtoType(TypeLocBuilder &TLB,
1831  SmallVector<QualType, 4> ParamTypes;
1832  const FunctionProtoType *T = TL.getTypePtr();
1833 
1834  // -- The types of the function parameters are those of the constructor.
1835  for (auto *OldParam : TL.getParams()) {
1836  ParmVarDecl *NewParam = transformFunctionTypeParam(OldParam, Args);
1837  if (!NewParam)
1838  return QualType();
1839  ParamTypes.push_back(NewParam->getType());
1840  Params.push_back(NewParam);
1841  }
1842 
1843  // -- The return type is the class template specialization designated by
1844  // the template-name and template arguments corresponding to the
1845  // template parameters obtained from the class template.
1846  //
1847  // We use the injected-class-name type of the primary template instead.
1848  // This has the convenient property that it is different from any type that
1849  // the user can write in a deduction-guide (because they cannot enter the
1850  // context of the template), so implicit deduction guides can never collide
1851  // with explicit ones.
1852  QualType ReturnType = DeducedType;
1853  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
1854 
1855  // Resolving a wording defect, we also inherit the variadicness of the
1856  // constructor.
1858  EPI.Variadic = T->isVariadic();
1859  EPI.HasTrailingReturn = true;
1860 
1861  QualType Result = SemaRef.BuildFunctionType(
1862  ReturnType, ParamTypes, TL.getLocStart(), DeductionGuideName, EPI);
1863  if (Result.isNull())
1864  return QualType();
1865 
1866  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
1868  NewTL.setLParenLoc(TL.getLParenLoc());
1869  NewTL.setRParenLoc(TL.getRParenLoc());
1871  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
1872  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
1873  NewTL.setParam(I, Params[I]);
1874 
1875  return Result;
1876  }
1877 
1878  ParmVarDecl *
1879  transformFunctionTypeParam(ParmVarDecl *OldParam,
1881  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
1882  TypeSourceInfo *NewDI;
1883  if (!Args.getNumLevels())
1884  NewDI = OldDI;
1885  else if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
1886  // Expand out the one and only element in each inner pack.
1887  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
1888  NewDI =
1889  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
1890  OldParam->getLocation(), OldParam->getDeclName());
1891  if (!NewDI) return nullptr;
1892  NewDI =
1893  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
1894  PackTL.getTypePtr()->getNumExpansions());
1895  } else
1896  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
1897  OldParam->getDeclName());
1898  if (!NewDI)
1899  return nullptr;
1900 
1901  // Canonicalize the type. This (for instance) replaces references to
1902  // typedef members of the current instantiations with the definitions of
1903  // those typedefs, avoiding triggering instantiation of the deduced type
1904  // during deduction.
1905  // FIXME: It would be preferable to retain type sugar and source
1906  // information here (and handle this in substitution instead).
1907  NewDI = SemaRef.Context.getTrivialTypeSourceInfo(
1908  SemaRef.Context.getCanonicalType(NewDI->getType()),
1909  OldParam->getLocation());
1910 
1911  // Resolving a wording defect, we also inherit default arguments from the
1912  // constructor.
1913  ExprResult NewDefArg;
1914  if (OldParam->hasDefaultArg()) {
1915  NewDefArg = Args.getNumLevels()
1916  ? SemaRef.SubstExpr(OldParam->getDefaultArg(), Args)
1917  : OldParam->getDefaultArg();
1918  if (NewDefArg.isInvalid())
1919  return nullptr;
1920  }
1921 
1922  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
1923  OldParam->getInnerLocStart(),
1924  OldParam->getLocation(),
1925  OldParam->getIdentifier(),
1926  NewDI->getType(),
1927  NewDI,
1928  OldParam->getStorageClass(),
1929  NewDefArg.get());
1930  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
1931  OldParam->getFunctionScopeIndex());
1932  return NewParam;
1933  }
1934 
1935  NamedDecl *buildDeductionGuide(TemplateParameterList *TemplateParams,
1936  bool Explicit, TypeSourceInfo *TInfo,
1937  SourceLocation LocStart, SourceLocation Loc,
1938  SourceLocation LocEnd) {
1939  DeclarationNameInfo Name(DeductionGuideName, Loc);
1940  ArrayRef<ParmVarDecl *> Params =
1941  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
1942 
1943  // Build the implicit deduction guide template.
1944  auto *Guide =
1945  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, Explicit,
1946  Name, TInfo->getType(), TInfo, LocEnd);
1947  Guide->setImplicit();
1948  Guide->setParams(Params);
1949 
1950  for (auto *Param : Params)
1951  Param->setDeclContext(Guide);
1952 
1953  auto *GuideTemplate = FunctionTemplateDecl::Create(
1954  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
1955  GuideTemplate->setImplicit();
1956  Guide->setDescribedFunctionTemplate(GuideTemplate);
1957 
1958  if (isa<CXXRecordDecl>(DC)) {
1959  Guide->setAccess(AS_public);
1960  GuideTemplate->setAccess(AS_public);
1961  }
1962 
1963  DC->addDecl(GuideTemplate);
1964  return GuideTemplate;
1965  }
1966 };
1967 }
1968 
1970  SourceLocation Loc) {
1971  DeclContext *DC = Template->getDeclContext();
1972  if (DC->isDependentContext())
1973  return;
1974 
1975  ConvertConstructorToDeductionGuideTransform Transform(
1976  *this, cast<ClassTemplateDecl>(Template));
1977  if (!isCompleteType(Loc, Transform.DeducedType))
1978  return;
1979 
1980  // Check whether we've already declared deduction guides for this template.
1981  // FIXME: Consider storing a flag on the template to indicate this.
1982  auto Existing = DC->lookup(Transform.DeductionGuideName);
1983  for (auto *D : Existing)
1984  if (D->isImplicit())
1985  return;
1986 
1987  // In case we were expanding a pack when we attempted to declare deduction
1988  // guides, turn off pack expansion for everything we're about to do.
1989  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
1990  // Create a template instantiation record to track the "instantiation" of
1991  // constructors into deduction guides.
1992  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
1993  // this substitution process actually fail?
1994  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
1995  if (BuildingDeductionGuides.isInvalid())
1996  return;
1997 
1998  // Convert declared constructors into deduction guide templates.
1999  // FIXME: Skip constructors for which deduction must necessarily fail (those
2000  // for which some class template parameter without a default argument never
2001  // appears in a deduced context).
2002  bool AddedAny = false;
2003  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2004  D = D->getUnderlyingDecl();
2005  if (D->isInvalidDecl() || D->isImplicit())
2006  continue;
2007  D = cast<NamedDecl>(D->getCanonicalDecl());
2008 
2009  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2010  auto *CD =
2011  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2012  // Class-scope explicit specializations (MS extension) do not result in
2013  // deduction guides.
2014  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2015  continue;
2016 
2017  Transform.transformConstructor(FTD, CD);
2018  AddedAny = true;
2019  }
2020 
2021  // C++17 [over.match.class.deduct]
2022  // -- If C is not defined or does not declare any constructors, an
2023  // additional function template derived as above from a hypothetical
2024  // constructor C().
2025  if (!AddedAny)
2026  Transform.buildSimpleDeductionGuide(None);
2027 
2028  // -- An additional function template derived as above from a hypothetical
2029  // constructor C(C), called the copy deduction candidate.
2030  cast<CXXDeductionGuideDecl>(
2031  cast<FunctionTemplateDecl>(
2032  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2033  ->getTemplatedDecl())
2034  ->setIsCopyDeductionCandidate();
2035 }
2036 
2037 /// Diagnose the presence of a default template argument on a
2038 /// template parameter, which is ill-formed in certain contexts.
2039 ///
2040 /// \returns true if the default template argument should be dropped.
2043  SourceLocation ParamLoc,
2044  SourceRange DefArgRange) {
2045  switch (TPC) {
2047  case Sema::TPC_VarTemplate:
2049  return false;
2050 
2053  // C++ [temp.param]p9:
2054  // A default template-argument shall not be specified in a
2055  // function template declaration or a function template
2056  // definition [...]
2057  // If a friend function template declaration specifies a default
2058  // template-argument, that declaration shall be a definition and shall be
2059  // the only declaration of the function template in the translation unit.
2060  // (C++98/03 doesn't have this wording; see DR226).
2061  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2062  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2063  : diag::ext_template_parameter_default_in_function_template)
2064  << DefArgRange;
2065  return false;
2066 
2068  // C++0x [temp.param]p9:
2069  // A default template-argument shall not be specified in the
2070  // template-parameter-lists of the definition of a member of a
2071  // class template that appears outside of the member's class.
2072  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2073  << DefArgRange;
2074  return true;
2075 
2078  // C++ [temp.param]p9:
2079  // A default template-argument shall not be specified in a
2080  // friend template declaration.
2081  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2082  << DefArgRange;
2083  return true;
2084 
2085  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2086  // for friend function templates if there is only a single
2087  // declaration (and it is a definition). Strange!
2088  }
2089 
2090  llvm_unreachable("Invalid TemplateParamListContext!");
2091 }
2092 
2093 /// Check for unexpanded parameter packs within the template parameters
2094 /// of a template template parameter, recursively.
2096  TemplateTemplateParmDecl *TTP) {
2097  // A template template parameter which is a parameter pack is also a pack
2098  // expansion.
2099  if (TTP->isParameterPack())
2100  return false;
2101 
2103  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2104  NamedDecl *P = Params->getParam(I);
2105  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2106  if (!NTTP->isParameterPack() &&
2107  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2108  NTTP->getTypeSourceInfo(),
2110  return true;
2111 
2112  continue;
2113  }
2114 
2115  if (TemplateTemplateParmDecl *InnerTTP
2116  = dyn_cast<TemplateTemplateParmDecl>(P))
2117  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2118  return true;
2119  }
2120 
2121  return false;
2122 }
2123 
2124 /// Checks the validity of a template parameter list, possibly
2125 /// considering the template parameter list from a previous
2126 /// declaration.
2127 ///
2128 /// If an "old" template parameter list is provided, it must be
2129 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2130 /// template parameter list.
2131 ///
2132 /// \param NewParams Template parameter list for a new template
2133 /// declaration. This template parameter list will be updated with any
2134 /// default arguments that are carried through from the previous
2135 /// template parameter list.
2136 ///
2137 /// \param OldParams If provided, template parameter list from a
2138 /// previous declaration of the same template. Default template
2139 /// arguments will be merged from the old template parameter list to
2140 /// the new template parameter list.
2141 ///
2142 /// \param TPC Describes the context in which we are checking the given
2143 /// template parameter list.
2144 ///
2145 /// \returns true if an error occurred, false otherwise.
2147  TemplateParameterList *OldParams,
2149  bool Invalid = false;
2150 
2151  // C++ [temp.param]p10:
2152  // The set of default template-arguments available for use with a
2153  // template declaration or definition is obtained by merging the
2154  // default arguments from the definition (if in scope) and all
2155  // declarations in scope in the same way default function
2156  // arguments are (8.3.6).
2157  bool SawDefaultArgument = false;
2158  SourceLocation PreviousDefaultArgLoc;
2159 
2160  // Dummy initialization to avoid warnings.
2161  TemplateParameterList::iterator OldParam = NewParams->end();
2162  if (OldParams)
2163  OldParam = OldParams->begin();
2164 
2165  bool RemoveDefaultArguments = false;
2166  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2167  NewParamEnd = NewParams->end();
2168  NewParam != NewParamEnd; ++NewParam) {
2169  // Variables used to diagnose redundant default arguments
2170  bool RedundantDefaultArg = false;
2171  SourceLocation OldDefaultLoc;
2172  SourceLocation NewDefaultLoc;
2173 
2174  // Variable used to diagnose missing default arguments
2175  bool MissingDefaultArg = false;
2176 
2177  // Variable used to diagnose non-final parameter packs
2178  bool SawParameterPack = false;
2179 
2180  if (TemplateTypeParmDecl *NewTypeParm
2181  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2182  // Check the presence of a default argument here.
2183  if (NewTypeParm->hasDefaultArgument() &&
2185  NewTypeParm->getLocation(),
2186  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2187  .getSourceRange()))
2188  NewTypeParm->removeDefaultArgument();
2189 
2190  // Merge default arguments for template type parameters.
2191  TemplateTypeParmDecl *OldTypeParm
2192  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2193  if (NewTypeParm->isParameterPack()) {
2194  assert(!NewTypeParm->hasDefaultArgument() &&
2195  "Parameter packs can't have a default argument!");
2196  SawParameterPack = true;
2197  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2198  NewTypeParm->hasDefaultArgument()) {
2199  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2200  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2201  SawDefaultArgument = true;
2202  RedundantDefaultArg = true;
2203  PreviousDefaultArgLoc = NewDefaultLoc;
2204  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2205  // Merge the default argument from the old declaration to the
2206  // new declaration.
2207  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2208  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2209  } else if (NewTypeParm->hasDefaultArgument()) {
2210  SawDefaultArgument = true;
2211  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2212  } else if (SawDefaultArgument)
2213  MissingDefaultArg = true;
2214  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2215  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2216  // Check for unexpanded parameter packs.
2217  if (!NewNonTypeParm->isParameterPack() &&
2218  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2219  NewNonTypeParm->getTypeSourceInfo(),
2220  UPPC_NonTypeTemplateParameterType)) {
2221  Invalid = true;
2222  continue;
2223  }
2224 
2225  // Check the presence of a default argument here.
2226  if (NewNonTypeParm->hasDefaultArgument() &&
2228  NewNonTypeParm->getLocation(),
2229  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2230  NewNonTypeParm->removeDefaultArgument();
2231  }
2232 
2233  // Merge default arguments for non-type template parameters
2234  NonTypeTemplateParmDecl *OldNonTypeParm
2235  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2236  if (NewNonTypeParm->isParameterPack()) {
2237  assert(!NewNonTypeParm->hasDefaultArgument() &&
2238  "Parameter packs can't have a default argument!");
2239  if (!NewNonTypeParm->isPackExpansion())
2240  SawParameterPack = true;
2241  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2242  NewNonTypeParm->hasDefaultArgument()) {
2243  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2244  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2245  SawDefaultArgument = true;
2246  RedundantDefaultArg = true;
2247  PreviousDefaultArgLoc = NewDefaultLoc;
2248  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2249  // Merge the default argument from the old declaration to the
2250  // new declaration.
2251  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2252  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2253  } else if (NewNonTypeParm->hasDefaultArgument()) {
2254  SawDefaultArgument = true;
2255  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2256  } else if (SawDefaultArgument)
2257  MissingDefaultArg = true;
2258  } else {
2259  TemplateTemplateParmDecl *NewTemplateParm
2260  = cast<TemplateTemplateParmDecl>(*NewParam);
2261 
2262  // Check for unexpanded parameter packs, recursively.
2263  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2264  Invalid = true;
2265  continue;
2266  }
2267 
2268  // Check the presence of a default argument here.
2269  if (NewTemplateParm->hasDefaultArgument() &&
2271  NewTemplateParm->getLocation(),
2272  NewTemplateParm->getDefaultArgument().getSourceRange()))
2273  NewTemplateParm->removeDefaultArgument();
2274 
2275  // Merge default arguments for template template parameters
2276  TemplateTemplateParmDecl *OldTemplateParm
2277  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2278  if (NewTemplateParm->isParameterPack()) {
2279  assert(!NewTemplateParm->hasDefaultArgument() &&
2280  "Parameter packs can't have a default argument!");
2281  if (!NewTemplateParm->isPackExpansion())
2282  SawParameterPack = true;
2283  } else if (OldTemplateParm &&
2284  hasVisibleDefaultArgument(OldTemplateParm) &&
2285  NewTemplateParm->hasDefaultArgument()) {
2286  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2287  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2288  SawDefaultArgument = true;
2289  RedundantDefaultArg = true;
2290  PreviousDefaultArgLoc = NewDefaultLoc;
2291  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2292  // Merge the default argument from the old declaration to the
2293  // new declaration.
2294  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2295  PreviousDefaultArgLoc
2296  = OldTemplateParm->getDefaultArgument().getLocation();
2297  } else if (NewTemplateParm->hasDefaultArgument()) {
2298  SawDefaultArgument = true;
2299  PreviousDefaultArgLoc
2300  = NewTemplateParm->getDefaultArgument().getLocation();
2301  } else if (SawDefaultArgument)
2302  MissingDefaultArg = true;
2303  }
2304 
2305  // C++11 [temp.param]p11:
2306  // If a template parameter of a primary class template or alias template
2307  // is a template parameter pack, it shall be the last template parameter.
2308  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2309  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2310  TPC == TPC_TypeAliasTemplate)) {
2311  Diag((*NewParam)->getLocation(),
2312  diag::err_template_param_pack_must_be_last_template_parameter);
2313  Invalid = true;
2314  }
2315 
2316  if (RedundantDefaultArg) {
2317  // C++ [temp.param]p12:
2318  // A template-parameter shall not be given default arguments
2319  // by two different declarations in the same scope.
2320  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2321  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2322  Invalid = true;
2323  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2324  // C++ [temp.param]p11:
2325  // If a template-parameter of a class template has a default
2326  // template-argument, each subsequent template-parameter shall either
2327  // have a default template-argument supplied or be a template parameter
2328  // pack.
2329  Diag((*NewParam)->getLocation(),
2330  diag::err_template_param_default_arg_missing);
2331  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2332  Invalid = true;
2333  RemoveDefaultArguments = true;
2334  }
2335 
2336  // If we have an old template parameter list that we're merging
2337  // in, move on to the next parameter.
2338  if (OldParams)
2339  ++OldParam;
2340  }
2341 
2342  // We were missing some default arguments at the end of the list, so remove
2343  // all of the default arguments.
2344  if (RemoveDefaultArguments) {
2345  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2346  NewParamEnd = NewParams->end();
2347  NewParam != NewParamEnd; ++NewParam) {
2348  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2349  TTP->removeDefaultArgument();
2350  else if (NonTypeTemplateParmDecl *NTTP
2351  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2352  NTTP->removeDefaultArgument();
2353  else
2354  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2355  }
2356  }
2357 
2358  return Invalid;
2359 }
2360 
2361 namespace {
2362 
2363 /// A class which looks for a use of a certain level of template
2364 /// parameter.
2365 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2367 
2368  unsigned Depth;
2369 
2370  // Whether we're looking for a use of a template parameter that makes the
2371  // overall construct type-dependent / a dependent type. This is strictly
2372  // best-effort for now; we may fail to match at all for a dependent type
2373  // in some cases if this is set.
2374  bool IgnoreNonTypeDependent;
2375 
2376  bool Match;
2377  SourceLocation MatchLoc;
2378 
2379  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2380  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2381  Match(false) {}
2382 
2383  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2384  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2385  NamedDecl *ND = Params->getParam(0);
2386  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2387  Depth = PD->getDepth();
2388  } else if (NonTypeTemplateParmDecl *PD =
2389  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2390  Depth = PD->getDepth();
2391  } else {
2392  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2393  }
2394  }
2395 
2396  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2397  if (ParmDepth >= Depth) {
2398  Match = true;
2399  MatchLoc = Loc;
2400  return true;
2401  }
2402  return false;
2403  }
2404 
2405  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2406  // Prune out non-type-dependent expressions if requested. This can
2407  // sometimes result in us failing to find a template parameter reference
2408  // (if a value-dependent expression creates a dependent type), but this
2409  // mode is best-effort only.
2410  if (auto *E = dyn_cast_or_null<Expr>(S))
2411  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2412  return true;
2413  return super::TraverseStmt(S, Q);
2414  }
2415 
2416  bool TraverseTypeLoc(TypeLoc TL) {
2417  if (IgnoreNonTypeDependent && !TL.isNull() &&
2418  !TL.getType()->isDependentType())
2419  return true;
2420  return super::TraverseTypeLoc(TL);
2421  }
2422 
2423  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2424  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2425  }
2426 
2427  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2428  // For a best-effort search, keep looking until we find a location.
2429  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2430  }
2431 
2432  bool TraverseTemplateName(TemplateName N) {
2433  if (TemplateTemplateParmDecl *PD =
2434  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2435  if (Matches(PD->getDepth()))
2436  return false;
2437  return super::TraverseTemplateName(N);
2438  }
2439 
2440  bool VisitDeclRefExpr(DeclRefExpr *E) {
2441  if (NonTypeTemplateParmDecl *PD =
2442  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2443  if (Matches(PD->getDepth(), E->getExprLoc()))
2444  return false;
2445  return super::VisitDeclRefExpr(E);
2446  }
2447 
2448  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2449  return TraverseType(T->getReplacementType());
2450  }
2451 
2452  bool
2453  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2454  return TraverseTemplateArgument(T->getArgumentPack());
2455  }
2456 
2457  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2458  return TraverseType(T->getInjectedSpecializationType());
2459  }
2460 };
2461 } // end anonymous namespace
2462 
2463 /// Determines whether a given type depends on the given parameter
2464 /// list.
2465 static bool
2467  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2468  Checker.TraverseType(T);
2469  return Checker.Match;
2470 }
2471 
2472 // Find the source range corresponding to the named type in the given
2473 // nested-name-specifier, if any.
2475  QualType T,
2476  const CXXScopeSpec &SS) {
2478  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2479  if (const Type *CurType = NNS->getAsType()) {
2480  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2481  return NNSLoc.getTypeLoc().getSourceRange();
2482  } else
2483  break;
2484 
2485  NNSLoc = NNSLoc.getPrefix();
2486  }
2487 
2488  return SourceRange();
2489 }
2490 
2491 /// Match the given template parameter lists to the given scope
2492 /// specifier, returning the template parameter list that applies to the
2493 /// name.
2494 ///
2495 /// \param DeclStartLoc the start of the declaration that has a scope
2496 /// specifier or a template parameter list.
2497 ///
2498 /// \param DeclLoc The location of the declaration itself.
2499 ///
2500 /// \param SS the scope specifier that will be matched to the given template
2501 /// parameter lists. This scope specifier precedes a qualified name that is
2502 /// being declared.
2503 ///
2504 /// \param TemplateId The template-id following the scope specifier, if there
2505 /// is one. Used to check for a missing 'template<>'.
2506 ///
2507 /// \param ParamLists the template parameter lists, from the outermost to the
2508 /// innermost template parameter lists.
2509 ///
2510 /// \param IsFriend Whether to apply the slightly different rules for
2511 /// matching template parameters to scope specifiers in friend
2512 /// declarations.
2513 ///
2514 /// \param IsMemberSpecialization will be set true if the scope specifier
2515 /// denotes a fully-specialized type, and therefore this is a declaration of
2516 /// a member specialization.
2517 ///
2518 /// \returns the template parameter list, if any, that corresponds to the
2519 /// name that is preceded by the scope specifier @p SS. This template
2520 /// parameter list may have template parameters (if we're declaring a
2521 /// template) or may have no template parameters (if we're declaring a
2522 /// template specialization), or may be NULL (if what we're declaring isn't
2523 /// itself a template).
2525  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
2526  TemplateIdAnnotation *TemplateId,
2527  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
2528  bool &IsMemberSpecialization, bool &Invalid) {
2529  IsMemberSpecialization = false;
2530  Invalid = false;
2531 
2532  // The sequence of nested types to which we will match up the template
2533  // parameter lists. We first build this list by starting with the type named
2534  // by the nested-name-specifier and walking out until we run out of types.
2535  SmallVector<QualType, 4> NestedTypes;
2536  QualType T;
2537  if (SS.getScopeRep()) {
2538  if (CXXRecordDecl *Record
2539  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
2540  T = Context.getTypeDeclType(Record);
2541  else
2542  T = QualType(SS.getScopeRep()->getAsType(), 0);
2543  }
2544 
2545  // If we found an explicit specialization that prevents us from needing
2546  // 'template<>' headers, this will be set to the location of that
2547  // explicit specialization.
2548  SourceLocation ExplicitSpecLoc;
2549 
2550  while (!T.isNull()) {
2551  NestedTypes.push_back(T);
2552 
2553  // Retrieve the parent of a record type.
2554  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2555  // If this type is an explicit specialization, we're done.
2557  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2558  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
2559  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
2560  ExplicitSpecLoc = Spec->getLocation();
2561  break;
2562  }
2563  } else if (Record->getTemplateSpecializationKind()
2565  ExplicitSpecLoc = Record->getLocation();
2566  break;
2567  }
2568 
2569  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
2570  T = Context.getTypeDeclType(Parent);
2571  else
2572  T = QualType();
2573  continue;
2574  }
2575 
2576  if (const TemplateSpecializationType *TST
2578  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2579  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
2580  T = Context.getTypeDeclType(Parent);
2581  else
2582  T = QualType();
2583  continue;
2584  }
2585  }
2586 
2587  // Look one step prior in a dependent template specialization type.
2588  if (const DependentTemplateSpecializationType *DependentTST
2590  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
2591  T = QualType(NNS->getAsType(), 0);
2592  else
2593  T = QualType();
2594  continue;
2595  }
2596 
2597  // Look one step prior in a dependent name type.
2598  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
2599  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
2600  T = QualType(NNS->getAsType(), 0);
2601  else
2602  T = QualType();
2603  continue;
2604  }
2605 
2606  // Retrieve the parent of an enumeration type.
2607  if (const EnumType *EnumT = T->getAs<EnumType>()) {
2608  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
2609  // check here.
2610  EnumDecl *Enum = EnumT->getDecl();
2611 
2612  // Get to the parent type.
2613  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
2614  T = Context.getTypeDeclType(Parent);
2615  else
2616  T = QualType();
2617  continue;
2618  }
2619 
2620  T = QualType();
2621  }
2622  // Reverse the nested types list, since we want to traverse from the outermost
2623  // to the innermost while checking template-parameter-lists.
2624  std::reverse(NestedTypes.begin(), NestedTypes.end());
2625 
2626  // C++0x [temp.expl.spec]p17:
2627  // A member or a member template may be nested within many
2628  // enclosing class templates. In an explicit specialization for
2629  // such a member, the member declaration shall be preceded by a
2630  // template<> for each enclosing class template that is
2631  // explicitly specialized.
2632  bool SawNonEmptyTemplateParameterList = false;
2633 
2634  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
2635  if (SawNonEmptyTemplateParameterList) {
2636  Diag(DeclLoc, diag::err_specialize_member_of_template)
2637  << !Recovery << Range;
2638  Invalid = true;
2639  IsMemberSpecialization = false;
2640  return true;
2641  }
2642 
2643  return false;
2644  };
2645 
2646  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
2647  // Check that we can have an explicit specialization here.
2648  if (CheckExplicitSpecialization(Range, true))
2649  return true;
2650 
2651  // We don't have a template header, but we should.
2652  SourceLocation ExpectedTemplateLoc;
2653  if (!ParamLists.empty())
2654  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
2655  else
2656  ExpectedTemplateLoc = DeclStartLoc;
2657 
2658  Diag(DeclLoc, diag::err_template_spec_needs_header)
2659  << Range
2660  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
2661  return false;
2662  };
2663 
2664  unsigned ParamIdx = 0;
2665  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
2666  ++TypeIdx) {
2667  T = NestedTypes[TypeIdx];
2668 
2669  // Whether we expect a 'template<>' header.
2670  bool NeedEmptyTemplateHeader = false;
2671 
2672  // Whether we expect a template header with parameters.
2673  bool NeedNonemptyTemplateHeader = false;
2674 
2675  // For a dependent type, the set of template parameters that we
2676  // expect to see.
2677  TemplateParameterList *ExpectedTemplateParams = nullptr;
2678 
2679  // C++0x [temp.expl.spec]p15:
2680  // A member or a member template may be nested within many enclosing
2681  // class templates. In an explicit specialization for such a member, the
2682  // member declaration shall be preceded by a template<> for each
2683  // enclosing class template that is explicitly specialized.
2684  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
2686  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
2687  ExpectedTemplateParams = Partial->getTemplateParameters();
2688  NeedNonemptyTemplateHeader = true;
2689  } else if (Record->isDependentType()) {
2690  if (Record->getDescribedClassTemplate()) {
2691  ExpectedTemplateParams = Record->getDescribedClassTemplate()
2692  ->getTemplateParameters();
2693  NeedNonemptyTemplateHeader = true;
2694  }
2695  } else if (ClassTemplateSpecializationDecl *Spec
2696  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
2697  // C++0x [temp.expl.spec]p4:
2698  // Members of an explicitly specialized class template are defined
2699  // in the same manner as members of normal classes, and not using
2700  // the template<> syntax.
2701  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
2702  NeedEmptyTemplateHeader = true;
2703  else
2704  continue;
2705  } else if (Record->getTemplateSpecializationKind()) {
2706  if (Record->getTemplateSpecializationKind()
2708  TypeIdx == NumTypes - 1)
2709  IsMemberSpecialization = true;
2710 
2711  continue;
2712  }
2713  } else if (const TemplateSpecializationType *TST
2715  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
2716  ExpectedTemplateParams = Template->getTemplateParameters();
2717  NeedNonemptyTemplateHeader = true;
2718  }
2719  } else if (T->getAs<DependentTemplateSpecializationType>()) {
2720  // FIXME: We actually could/should check the template arguments here
2721  // against the corresponding template parameter list.
2722  NeedNonemptyTemplateHeader = false;
2723  }
2724 
2725  // C++ [temp.expl.spec]p16:
2726  // In an explicit specialization declaration for a member of a class
2727  // template or a member template that ap- pears in namespace scope, the
2728  // member template and some of its enclosing class templates may remain
2729  // unspecialized, except that the declaration shall not explicitly
2730  // specialize a class member template if its en- closing class templates
2731  // are not explicitly specialized as well.
2732  if (ParamIdx < ParamLists.size()) {
2733  if (ParamLists[ParamIdx]->size() == 0) {
2734  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2735  false))
2736  return nullptr;
2737  } else
2738  SawNonEmptyTemplateParameterList = true;
2739  }
2740 
2741  if (NeedEmptyTemplateHeader) {
2742  // If we're on the last of the types, and we need a 'template<>' header
2743  // here, then it's a member specialization.
2744  if (TypeIdx == NumTypes - 1)
2745  IsMemberSpecialization = true;
2746 
2747  if (ParamIdx < ParamLists.size()) {
2748  if (ParamLists[ParamIdx]->size() > 0) {
2749  // The header has template parameters when it shouldn't. Complain.
2750  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2751  diag::err_template_param_list_matches_nontemplate)
2752  << T
2753  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
2754  ParamLists[ParamIdx]->getRAngleLoc())
2755  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2756  Invalid = true;
2757  return nullptr;
2758  }
2759 
2760  // Consume this template header.
2761  ++ParamIdx;
2762  continue;
2763  }
2764 
2765  if (!IsFriend)
2766  if (DiagnoseMissingExplicitSpecialization(
2767  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
2768  return nullptr;
2769 
2770  continue;
2771  }
2772 
2773  if (NeedNonemptyTemplateHeader) {
2774  // In friend declarations we can have template-ids which don't
2775  // depend on the corresponding template parameter lists. But
2776  // assume that empty parameter lists are supposed to match this
2777  // template-id.
2778  if (IsFriend && T->isDependentType()) {
2779  if (ParamIdx < ParamLists.size() &&
2780  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
2781  ExpectedTemplateParams = nullptr;
2782  else
2783  continue;
2784  }
2785 
2786  if (ParamIdx < ParamLists.size()) {
2787  // Check the template parameter list, if we can.
2788  if (ExpectedTemplateParams &&
2789  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
2790  ExpectedTemplateParams,
2791  true, TPL_TemplateMatch))
2792  Invalid = true;
2793 
2794  if (!Invalid &&
2795  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
2796  TPC_ClassTemplateMember))
2797  Invalid = true;
2798 
2799  ++ParamIdx;
2800  continue;
2801  }
2802 
2803  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
2804  << T
2805  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
2806  Invalid = true;
2807  continue;
2808  }
2809  }
2810 
2811  // If there were at least as many template-ids as there were template
2812  // parameter lists, then there are no template parameter lists remaining for
2813  // the declaration itself.
2814  if (ParamIdx >= ParamLists.size()) {
2815  if (TemplateId && !IsFriend) {
2816  // We don't have a template header for the declaration itself, but we
2817  // should.
2818  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
2819  TemplateId->RAngleLoc));
2820 
2821  // Fabricate an empty template parameter list for the invented header.
2823  SourceLocation(), None,
2824  SourceLocation(), nullptr);
2825  }
2826 
2827  return nullptr;
2828  }
2829 
2830  // If there were too many template parameter lists, complain about that now.
2831  if (ParamIdx < ParamLists.size() - 1) {
2832  bool HasAnyExplicitSpecHeader = false;
2833  bool AllExplicitSpecHeaders = true;
2834  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
2835  if (ParamLists[I]->size() == 0)
2836  HasAnyExplicitSpecHeader = true;
2837  else
2838  AllExplicitSpecHeaders = false;
2839  }
2840 
2841  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
2842  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
2843  : diag::err_template_spec_extra_headers)
2844  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
2845  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
2846 
2847  // If there was a specialization somewhere, such that 'template<>' is
2848  // not required, and there were any 'template<>' headers, note where the
2849  // specialization occurred.
2850  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
2851  Diag(ExplicitSpecLoc,
2852  diag::note_explicit_template_spec_does_not_need_header)
2853  << NestedTypes.back();
2854 
2855  // We have a template parameter list with no corresponding scope, which
2856  // means that the resulting template declaration can't be instantiated
2857  // properly (we'll end up with dependent nodes when we shouldn't).
2858  if (!AllExplicitSpecHeaders)
2859  Invalid = true;
2860  }
2861 
2862  // C++ [temp.expl.spec]p16:
2863  // In an explicit specialization declaration for a member of a class
2864  // template or a member template that ap- pears in namespace scope, the
2865  // member template and some of its enclosing class templates may remain
2866  // unspecialized, except that the declaration shall not explicitly
2867  // specialize a class member template if its en- closing class templates
2868  // are not explicitly specialized as well.
2869  if (ParamLists.back()->size() == 0 &&
2870  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2871  false))
2872  return nullptr;
2873 
2874  // Return the last template parameter list, which corresponds to the
2875  // entity being declared.
2876  return ParamLists.back();
2877 }
2878 
2880  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
2881  Diag(Template->getLocation(), diag::note_template_declared_here)
2882  << (isa<FunctionTemplateDecl>(Template)
2883  ? 0
2884  : isa<ClassTemplateDecl>(Template)
2885  ? 1
2886  : isa<VarTemplateDecl>(Template)
2887  ? 2
2888  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
2889  << Template->getDeclName();
2890  return;
2891  }
2892 
2894  for (OverloadedTemplateStorage::iterator I = OST->begin(),
2895  IEnd = OST->end();
2896  I != IEnd; ++I)
2897  Diag((*I)->getLocation(), diag::note_template_declared_here)
2898  << 0 << (*I)->getDeclName();
2899 
2900  return;
2901  }
2902 }
2903 
2904 static QualType
2906  const SmallVectorImpl<TemplateArgument> &Converted,
2907  SourceLocation TemplateLoc,
2908  TemplateArgumentListInfo &TemplateArgs) {
2909  ASTContext &Context = SemaRef.getASTContext();
2910  switch (BTD->getBuiltinTemplateKind()) {
2911  case BTK__make_integer_seq: {
2912  // Specializations of __make_integer_seq<S, T, N> are treated like
2913  // S<T, 0, ..., N-1>.
2914 
2915  // C++14 [inteseq.intseq]p1:
2916  // T shall be an integer type.
2917  if (!Converted[1].getAsType()->isIntegralType(Context)) {
2918  SemaRef.Diag(TemplateArgs[1].getLocation(),
2919  diag::err_integer_sequence_integral_element_type);
2920  return QualType();
2921  }
2922 
2923  // C++14 [inteseq.make]p1:
2924  // If N is negative the program is ill-formed.
2925  TemplateArgument NumArgsArg = Converted[2];
2926  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
2927  if (NumArgs < 0) {
2928  SemaRef.Diag(TemplateArgs[2].getLocation(),
2929  diag::err_integer_sequence_negative_length);
2930  return QualType();
2931  }
2932 
2933  QualType ArgTy = NumArgsArg.getIntegralType();
2934  TemplateArgumentListInfo SyntheticTemplateArgs;
2935  // The type argument gets reused as the first template argument in the
2936  // synthetic template argument list.
2937  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
2938  // Expand N into 0 ... N-1.
2939  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
2940  I < NumArgs; ++I) {
2941  TemplateArgument TA(Context, I, ArgTy);
2942  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
2943  TA, ArgTy, TemplateArgs[2].getLocation()));
2944  }
2945  // The first template argument will be reused as the template decl that
2946  // our synthetic template arguments will be applied to.
2947  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
2948  TemplateLoc, SyntheticTemplateArgs);
2949  }
2950 
2952  // Specializations of
2953  // __type_pack_element<Index, T_1, ..., T_N>
2954  // are treated like T_Index.
2955  assert(Converted.size() == 2 &&
2956  "__type_pack_element should be given an index and a parameter pack");
2957 
2958  // If the Index is out of bounds, the program is ill-formed.
2959  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
2960  llvm::APSInt Index = IndexArg.getAsIntegral();
2961  assert(Index >= 0 && "the index used with __type_pack_element should be of "
2962  "type std::size_t, and hence be non-negative");
2963  if (Index >= Ts.pack_size()) {
2964  SemaRef.Diag(TemplateArgs[0].getLocation(),
2965  diag::err_type_pack_element_out_of_bounds);
2966  return QualType();
2967  }
2968 
2969  // We simply return the type at index `Index`.
2970  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
2971  return Nth->getAsType();
2972  }
2973  llvm_unreachable("unexpected BuiltinTemplateDecl!");
2974 }
2975 
2976 /// Determine whether this alias template is "enable_if_t".
2977 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
2978  return AliasTemplate->getName().equals("enable_if_t");
2979 }
2980 
2981 /// Collect all of the separable terms in the given condition, which
2982 /// might be a conjunction.
2983 ///
2984 /// FIXME: The right answer is to convert the logical expression into
2985 /// disjunctive normal form, so we can find the first failed term
2986 /// within each possible clause.
2987 static void collectConjunctionTerms(Expr *Clause,
2988  SmallVectorImpl<Expr *> &Terms) {
2989  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
2990  if (BinOp->getOpcode() == BO_LAnd) {
2991  collectConjunctionTerms(BinOp->getLHS(), Terms);
2992  collectConjunctionTerms(BinOp->getRHS(), Terms);
2993  }
2994 
2995  return;
2996  }
2997 
2998  Terms.push_back(Clause);
2999 }
3000 
3001 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3002 // a left-hand side that is value-dependent but never true. Identify
3003 // the idiom and ignore that term.
3005  // Top-level '||'.
3006  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3007  if (!BinOp) return Cond;
3008 
3009  if (BinOp->getOpcode() != BO_LOr) return Cond;
3010 
3011  // With an inner '==' that has a literal on the right-hand side.
3012  Expr *LHS = BinOp->getLHS();
3013  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3014  if (!InnerBinOp) return Cond;
3015 
3016  if (InnerBinOp->getOpcode() != BO_EQ ||
3017  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3018  return Cond;
3019 
3020  // If the inner binary operation came from a macro expansion named
3021  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3022  // of the '||', which is the real, user-provided condition.
3023  SourceLocation Loc = InnerBinOp->getExprLoc();
3024  if (!Loc.isMacroID()) return Cond;
3025 
3026  StringRef MacroName = PP.getImmediateMacroName(Loc);
3027  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3028  return BinOp->getRHS();
3029 
3030  return Cond;
3031 }
3032 
3033 std::pair<Expr *, std::string>
3034 Sema::findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond) {
3035  Cond = lookThroughRangesV3Condition(PP, Cond);
3036 
3037  // Separate out all of the terms in a conjunction.
3038  SmallVector<Expr *, 4> Terms;
3039  collectConjunctionTerms(Cond, Terms);
3040 
3041  // Determine which term failed.
3042  Expr *FailedCond = nullptr;
3043  for (Expr *Term : Terms) {
3044  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3045 
3046  // Literals are uninteresting.
3047  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3048  isa<IntegerLiteral>(TermAsWritten))
3049  continue;
3050 
3051  // The initialization of the parameter from the argument is
3052  // a constant-evaluated context.
3053  EnterExpressionEvaluationContext ConstantEvaluated(
3055 
3056  bool Succeeded;
3057  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3058  !Succeeded) {
3059  FailedCond = TermAsWritten;
3060  break;
3061  }
3062  }
3063 
3064  if (!FailedCond) {
3065  if (!AllowTopLevelCond)
3066  return { nullptr, "" };
3067 
3068  FailedCond = Cond->IgnoreParenImpCasts();
3069  }
3070 
3071  std::string Description;
3072  {
3073  llvm::raw_string_ostream Out(Description);
3074  FailedCond->printPretty(Out, nullptr, getPrintingPolicy());
3075  }
3076  return { FailedCond, Description };
3077 }
3078 
3080  SourceLocation TemplateLoc,
3081  TemplateArgumentListInfo &TemplateArgs) {
3084  if (DTN && DTN->isIdentifier())
3085  // When building a template-id where the template-name is dependent,
3086  // assume the template is a type template. Either our assumption is
3087  // correct, or the code is ill-formed and will be diagnosed when the
3088  // dependent name is substituted.
3090  DTN->getQualifier(),
3091  DTN->getIdentifier(),
3092  TemplateArgs);
3093 
3094  TemplateDecl *Template = Name.getAsTemplateDecl();
3095  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3096  isa<VarTemplateDecl>(Template)) {
3097  // We might have a substituted template template parameter pack. If so,
3098  // build a template specialization type for it.
3100  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3101 
3102  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3103  << Name;
3104  NoteAllFoundTemplates(Name);
3105  return QualType();
3106  }
3107 
3108  // Check that the template argument list is well-formed for this
3109  // template.
3111  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3112  false, Converted))
3113  return QualType();
3114 
3115  QualType CanonType;
3116 
3117  bool InstantiationDependent = false;
3118  if (TypeAliasTemplateDecl *AliasTemplate =
3119  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3120  // Find the canonical type for this type alias template specialization.
3121  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3122  if (Pattern->isInvalidDecl())
3123  return QualType();
3124 
3126  Converted);
3127 
3128  // Only substitute for the innermost template argument list.
3129  MultiLevelTemplateArgumentList TemplateArgLists;
3130  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3131  unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
3132  for (unsigned I = 0; I < Depth; ++I)
3133  TemplateArgLists.addOuterTemplateArguments(None);
3134 
3136  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3137  if (Inst.isInvalid())
3138  return QualType();
3139 
3140  CanonType = SubstType(Pattern->getUnderlyingType(),
3141  TemplateArgLists, AliasTemplate->getLocation(),
3142  AliasTemplate->getDeclName());
3143  if (CanonType.isNull()) {
3144  // If this was enable_if and we failed to find the nested type
3145  // within enable_if in a SFINAE context, dig out the specific
3146  // enable_if condition that failed and present that instead.
3147  if (isEnableIfAliasTemplate(AliasTemplate)) {
3148  if (auto DeductionInfo = isSFINAEContext()) {
3149  if (*DeductionInfo &&
3150  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3151  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3152  diag::err_typename_nested_not_found_enable_if &&
3153  TemplateArgs[0].getArgument().getKind()
3155  Expr *FailedCond;
3156  std::string FailedDescription;
3157  std::tie(FailedCond, FailedDescription) =
3158  findFailedBooleanCondition(
3159  TemplateArgs[0].getSourceExpression(),
3160  /*AllowTopLevelCond=*/true);
3161 
3162  // Remove the old SFINAE diagnostic.
3163  PartialDiagnosticAt OldDiag =
3165  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3166 
3167  // Add a new SFINAE diagnostic specifying which condition
3168  // failed.
3169  (*DeductionInfo)->addSFINAEDiagnostic(
3170  OldDiag.first,
3171  PDiag(diag::err_typename_nested_not_found_requirement)
3172  << FailedDescription
3173  << FailedCond->getSourceRange());
3174  }
3175  }
3176  }
3177 
3178  return QualType();
3179  }
3180  } else if (Name.isDependent() ||
3182  TemplateArgs, InstantiationDependent)) {
3183  // This class template specialization is a dependent
3184  // type. Therefore, its canonical type is another class template
3185  // specialization type that contains all of the converted
3186  // arguments in canonical form. This ensures that, e.g., A<T> and
3187  // A<T, T> have identical types when A is declared as:
3188  //
3189  // template<typename T, typename U = T> struct A;
3190  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3191 
3192  // This might work out to be a current instantiation, in which
3193  // case the canonical type needs to be the InjectedClassNameType.
3194  //
3195  // TODO: in theory this could be a simple hashtable lookup; most
3196  // changes to CurContext don't change the set of current
3197  // instantiations.
3198  if (isa<ClassTemplateDecl>(Template)) {
3199  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3200  // If we get out to a namespace, we're done.
3201  if (Ctx->isFileContext()) break;
3202 
3203  // If this isn't a record, keep looking.
3204  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3205  if (!Record) continue;
3206 
3207  // Look for one of the two cases with InjectedClassNameTypes
3208  // and check whether it's the same template.
3209  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3210  !Record->getDescribedClassTemplate())
3211  continue;
3212 
3213  // Fetch the injected class name type and check whether its
3214  // injected type is equal to the type we just built.
3215  QualType ICNT = Context.getTypeDeclType(Record);
3216  QualType Injected = cast<InjectedClassNameType>(ICNT)
3217  ->getInjectedSpecializationType();
3218 
3219  if (CanonType != Injected->getCanonicalTypeInternal())
3220  continue;
3221 
3222  // If so, the canonical type of this TST is the injected
3223  // class name type of the record we just found.
3224  assert(ICNT.isCanonical());
3225  CanonType = ICNT;
3226  break;
3227  }
3228  }
3229  } else if (ClassTemplateDecl *ClassTemplate
3230  = dyn_cast<ClassTemplateDecl>(Template)) {
3231  // Find the class template specialization declaration that
3232  // corresponds to these arguments.
3233  void *InsertPos = nullptr;
3235  = ClassTemplate->findSpecialization(Converted, InsertPos);
3236  if (!Decl) {
3237  // This is the first time we have referenced this class template
3238  // specialization. Create the canonical declaration and add it to
3239  // the set of specializations.
3241  ClassTemplate->getTemplatedDecl()->getTagKind(),
3242  ClassTemplate->getDeclContext(),
3243  ClassTemplate->getTemplatedDecl()->getLocStart(),
3244  ClassTemplate->getLocation(),
3245  ClassTemplate,
3246  Converted, nullptr);
3247  ClassTemplate->AddSpecialization(Decl, InsertPos);
3248  if (ClassTemplate->isOutOfLine())
3249  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3250  }
3251 
3252  if (Decl->getSpecializationKind() == TSK_Undeclared) {
3253  MultiLevelTemplateArgumentList TemplateArgLists;
3254  TemplateArgLists.addOuterTemplateArguments(Converted);
3255  InstantiateAttrsForDecl(TemplateArgLists, ClassTemplate->getTemplatedDecl(),
3256  Decl);
3257  }
3258 
3259  // Diagnose uses of this specialization.
3260  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3261 
3262  CanonType = Context.getTypeDeclType(Decl);
3263  assert(isa<RecordType>(CanonType) &&
3264  "type of non-dependent specialization is not a RecordType");
3265  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3266  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3267  TemplateArgs);
3268  }
3269 
3270  // Build the fully-sugared type for this class template
3271  // specialization, which refers back to the class template
3272  // specialization we created or found.
3273  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3274 }
3275 
3276 TypeResult
3278  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3279  SourceLocation TemplateIILoc,
3280  SourceLocation LAngleLoc,
3281  ASTTemplateArgsPtr TemplateArgsIn,
3282  SourceLocation RAngleLoc,
3283  bool IsCtorOrDtorName, bool IsClassName) {
3284  if (SS.isInvalid())
3285  return true;
3286 
3287  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3288  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3289 
3290  // C++ [temp.res]p3:
3291  // A qualified-id that refers to a type and in which the
3292  // nested-name-specifier depends on a template-parameter (14.6.2)
3293  // shall be prefixed by the keyword typename to indicate that the
3294  // qualified-id denotes a type, forming an
3295  // elaborated-type-specifier (7.1.5.3).
3296  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3297  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3298  << SS.getScopeRep() << TemplateII->getName();
3299  // Recover as if 'typename' were specified.
3300  // FIXME: This is not quite correct recovery as we don't transform SS
3301  // into the corresponding dependent form (and we don't diagnose missing
3302  // 'template' keywords within SS as a result).
3303  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3304  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3305  TemplateArgsIn, RAngleLoc);
3306  }
3307 
3308  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3309  // it's not actually allowed to be used as a type in most cases. Because
3310  // we annotate it before we know whether it's valid, we have to check for
3311  // this case here.
3312  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3313  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3314  Diag(TemplateIILoc,
3315  TemplateKWLoc.isInvalid()
3316  ? diag::err_out_of_line_qualified_id_type_names_constructor
3317  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3318  << TemplateII << 0 /*injected-class-name used as template name*/
3319  << 1 /*if any keyword was present, it was 'template'*/;
3320  }
3321  }
3322 
3323  TemplateName Template = TemplateD.get();
3324 
3325  // Translate the parser's template argument list in our AST format.
3326  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3327  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3328 
3329  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3330  QualType T
3332  DTN->getQualifier(),
3333  DTN->getIdentifier(),
3334  TemplateArgs);
3335  // Build type-source information.
3336  TypeLocBuilder TLB;
3340  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3341  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3342  SpecTL.setTemplateNameLoc(TemplateIILoc);
3343  SpecTL.setLAngleLoc(LAngleLoc);
3344  SpecTL.setRAngleLoc(RAngleLoc);
3345  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3346  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3347  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3348  }
3349 
3350  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3351  if (Result.isNull())
3352  return true;
3353 
3354  // Build type-source information.
3355  TypeLocBuilder TLB;
3357  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3358  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3359  SpecTL.setTemplateNameLoc(TemplateIILoc);
3360  SpecTL.setLAngleLoc(LAngleLoc);
3361  SpecTL.setRAngleLoc(RAngleLoc);
3362  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3363  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3364 
3365  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3366  // constructor or destructor name (in such a case, the scope specifier
3367  // will be attached to the enclosing Decl or Expr node).
3368  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3369  // Create an elaborated-type-specifier containing the nested-name-specifier.
3370  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3371  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3373  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3374  }
3375 
3376  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3377 }
3378 
3380  TypeSpecifierType TagSpec,
3381  SourceLocation TagLoc,
3382  CXXScopeSpec &SS,
3383  SourceLocation TemplateKWLoc,
3384  TemplateTy TemplateD,
3385  SourceLocation TemplateLoc,
3386  SourceLocation LAngleLoc,
3387  ASTTemplateArgsPtr TemplateArgsIn,
3388  SourceLocation RAngleLoc) {
3389  TemplateName Template = TemplateD.get();
3390 
3391  // Translate the parser's template argument list in our AST format.
3392  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3393  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3394 
3395  // Determine the tag kind
3397  ElaboratedTypeKeyword Keyword
3399 
3400  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3402  DTN->getQualifier(),
3403  DTN->getIdentifier(),
3404  TemplateArgs);
3405 
3406  // Build type-source information.
3407  TypeLocBuilder TLB;
3410  SpecTL.setElaboratedKeywordLoc(TagLoc);
3411  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3412  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3413  SpecTL.setTemplateNameLoc(TemplateLoc);
3414  SpecTL.setLAngleLoc(LAngleLoc);
3415  SpecTL.setRAngleLoc(RAngleLoc);
3416  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3417  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3418  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3419  }
3420 
3421  if (TypeAliasTemplateDecl *TAT =
3422  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
3423  // C++0x [dcl.type.elab]p2:
3424  // If the identifier resolves to a typedef-name or the simple-template-id
3425  // resolves to an alias template specialization, the
3426  // elaborated-type-specifier is ill-formed.
3427  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
3428  << TAT << NTK_TypeAliasTemplate << TagKind;
3429  Diag(TAT->getLocation(), diag::note_declared_at);
3430  }
3431 
3432  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
3433  if (Result.isNull())
3434  return TypeResult(true);
3435 
3436  // Check the tag kind
3437  if (const RecordType *RT = Result->getAs<RecordType>()) {
3438  RecordDecl *D = RT->getDecl();
3439 
3441  assert(Id && "templated class must have an identifier");
3442 
3443  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
3444  TagLoc, Id)) {
3445  Diag(TagLoc, diag::err_use_with_wrong_tag)
3446  << Result
3448  Diag(D->getLocation(), diag::note_previous_use);
3449  }
3450  }
3451 
3452  // Provide source-location information for the template specialization.
3453  TypeLocBuilder TLB;
3455  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3456  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3457  SpecTL.setTemplateNameLoc(TemplateLoc);
3458  SpecTL.setLAngleLoc(LAngleLoc);
3459  SpecTL.setRAngleLoc(RAngleLoc);
3460  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3461  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3462 
3463  // Construct an elaborated type containing the nested-name-specifier (if any)
3464  // and tag keyword.
3465  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
3466  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3467  ElabTL.setElaboratedKeywordLoc(TagLoc);
3468  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3469  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3470 }
3471 
3472 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
3473  NamedDecl *PrevDecl,
3474  SourceLocation Loc,
3476 
3478 
3480  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
3481  switch (Arg.getKind()) {
3488  return false;
3489 
3490  case TemplateArgument::Type: {
3491  QualType Type = Arg.getAsType();
3492  const TemplateTypeParmType *TPT =
3494  return TPT && !Type.hasQualifiers() &&
3495  TPT->getDepth() == Depth && TPT->getIndex() == Index;
3496  }
3497 
3499  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
3500  if (!DRE || !DRE->getDecl())
3501  return false;
3502  const NonTypeTemplateParmDecl *NTTP =
3503  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
3504  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
3505  }
3506 
3508  const TemplateTemplateParmDecl *TTP =
3509  dyn_cast_or_null<TemplateTemplateParmDecl>(
3511  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
3512  }
3513  llvm_unreachable("unexpected kind of template argument");
3514 }
3515 
3518  if (Params->size() != Args.size())
3519  return false;
3520 
3521  unsigned Depth = Params->getDepth();
3522 
3523  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
3524  TemplateArgument Arg = Args[I];
3525 
3526  // If the parameter is a pack expansion, the argument must be a pack
3527  // whose only element is a pack expansion.
3528  if (Params->getParam(I)->isParameterPack()) {
3529  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
3530  !Arg.pack_begin()->isPackExpansion())
3531  return false;
3532  Arg = Arg.pack_begin()->getPackExpansionPattern();
3533  }
3534 
3535  if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
3536  return false;
3537  }
3538 
3539  return true;
3540 }
3541 
3542 /// Convert the parser's template argument list representation into our form.
3545  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
3546  TemplateId.RAngleLoc);
3547  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
3548  TemplateId.NumArgs);
3549  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
3550  return TemplateArgs;
3551 }
3552 
3553 template<typename PartialSpecDecl>
3554 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
3555  if (Partial->getDeclContext()->isDependentContext())
3556  return;
3557 
3558  // FIXME: Get the TDK from deduction in order to provide better diagnostics
3559  // for non-substitution-failure issues?
3560  TemplateDeductionInfo Info(Partial->getLocation());
3561  if (S.isMoreSpecializedThanPrimary(Partial, Info))
3562  return;
3563 
3564  auto *Template = Partial->getSpecializedTemplate();
3565  S.Diag(Partial->getLocation(),
3566  diag::ext_partial_spec_not_more_specialized_than_primary)
3567  << isa<VarTemplateDecl>(Template);
3568 
3569  if (Info.hasSFINAEDiagnostic()) {
3572  Info.takeSFINAEDiagnostic(Diag);
3573  SmallString<128> SFINAEArgString;
3574  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
3575  S.Diag(Diag.first,
3576  diag::note_partial_spec_not_more_specialized_than_primary)
3577  << SFINAEArgString;
3578  }
3579 
3580  S.Diag(Template->getLocation(), diag::note_template_decl_here);
3581 }
3582 
3583 static void
3585  const llvm::SmallBitVector &DeducibleParams) {
3586  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
3587  if (!DeducibleParams[I]) {
3588  NamedDecl *Param = TemplateParams->getParam(I);
3589  if (Param->getDeclName())
3590  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3591  << Param->getDeclName();
3592  else
3593  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
3594  << "(anonymous)";
3595  }
3596  }
3597 }
3598 
3599 
3600 template<typename PartialSpecDecl>
3602  PartialSpecDecl *Partial) {
3603  // C++1z [temp.class.spec]p8: (DR1495)
3604  // - The specialization shall be more specialized than the primary
3605  // template (14.5.5.2).
3606  checkMoreSpecializedThanPrimary(S, Partial);
3607 
3608  // C++ [temp.class.spec]p8: (DR1315)
3609  // - Each template-parameter shall appear at least once in the
3610  // template-id outside a non-deduced context.
3611  // C++1z [temp.class.spec.match]p3 (P0127R2)
3612  // If the template arguments of a partial specialization cannot be
3613  // deduced because of the structure of its template-parameter-list
3614  // and the template-id, the program is ill-formed.
3615  auto *TemplateParams = Partial->getTemplateParameters();
3616  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3617  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
3618  TemplateParams->getDepth(), DeducibleParams);
3619 
3620  if (!DeducibleParams.all()) {
3621  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3622  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
3623  << isa<VarTemplatePartialSpecializationDecl>(Partial)
3624  << (NumNonDeducible > 1)
3625  << SourceRange(Partial->getLocation(),
3626  Partial->getTemplateArgsAsWritten()->RAngleLoc);
3627  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
3628  }
3629 }
3630 
3633  checkTemplatePartialSpecialization(*this, Partial);
3634 }
3635 
3638  checkTemplatePartialSpecialization(*this, Partial);
3639 }
3640 
3642  // C++1z [temp.param]p11:
3643  // A template parameter of a deduction guide template that does not have a
3644  // default-argument shall be deducible from the parameter-type-list of the
3645  // deduction guide template.
3646  auto *TemplateParams = TD->getTemplateParameters();
3647  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
3648  MarkDeducedTemplateParameters(TD, DeducibleParams);
3649  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
3650  // A parameter pack is deducible (to an empty pack).
3651  auto *Param = TemplateParams->getParam(I);
3652  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
3653  DeducibleParams[I] = true;
3654  }
3655 
3656  if (!DeducibleParams.all()) {
3657  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
3658  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
3659  << (NumNonDeducible > 1);
3660  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
3661  }
3662 }
3663 
3665  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
3666  TemplateParameterList *TemplateParams, StorageClass SC,
3667  bool IsPartialSpecialization) {
3668  // D must be variable template id.
3670  "Variable template specialization is declared with a template it.");
3671 
3672  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
3673  TemplateArgumentListInfo TemplateArgs =
3674  makeTemplateArgumentListInfo(*this, *TemplateId);
3675  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
3676  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
3677  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
3678 
3679  TemplateName Name = TemplateId->Template.get();
3680 
3681  // The template-id must name a variable template.
3682  VarTemplateDecl *VarTemplate =
3683  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
3684  if (!VarTemplate) {
3685  NamedDecl *FnTemplate;
3686  if (auto *OTS = Name.getAsOverloadedTemplate())
3687  FnTemplate = *OTS->begin();
3688  else
3689  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
3690  if (FnTemplate)
3691  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
3692  << FnTemplate->getDeclName();
3693  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
3694  << IsPartialSpecialization;
3695  }
3696 
3697  // Check for unexpanded parameter packs in any of the template arguments.
3698  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
3699  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
3700  UPPC_PartialSpecialization))
3701  return true;
3702 
3703  // Check that the template argument list is well-formed for this
3704  // template.
3706  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
3707  false, Converted))
3708  return true;
3709 
3710  // Find the variable template (partial) specialization declaration that
3711  // corresponds to these arguments.
3712  if (IsPartialSpecialization) {
3713  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
3714  TemplateArgs.size(), Converted))
3715  return true;
3716 
3717  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
3718  // also do them during instantiation.
3719  bool InstantiationDependent;
3720  if (!Name.isDependent() &&
3722  TemplateArgs.arguments(),
3723  InstantiationDependent)) {
3724  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
3725  << VarTemplate->getDeclName();
3726  IsPartialSpecialization = false;
3727  }
3728 
3730  Converted)) {
3731  // C++ [temp.class.spec]p9b3:
3732  //
3733  // -- The argument list of the specialization shall not be identical
3734  // to the implicit argument list of the primary template.
3735  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
3736  << /*variable template*/ 1
3737  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
3738  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
3739  // FIXME: Recover from this by treating the declaration as a redeclaration
3740  // of the primary template.
3741  return true;
3742  }
3743  }
3744 
3745  void *InsertPos = nullptr;
3746  VarTemplateSpecializationDecl *PrevDecl = nullptr;
3747 
3748  if (IsPartialSpecialization)
3749  // FIXME: Template parameter list matters too
3750  PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
3751  else
3752  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
3753 
3754  VarTemplateSpecializationDecl *Specialization = nullptr;
3755 
3756  // Check whether we can declare a variable template specialization in
3757  // the current scope.
3758  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
3759  TemplateNameLoc,
3760  IsPartialSpecialization))
3761  return true;
3762 
3763  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
3764  // Since the only prior variable template specialization with these
3765  // arguments was referenced but not declared, reuse that
3766  // declaration node as our own, updating its source location and
3767  // the list of outer template parameters to reflect our new declaration.
3768  Specialization = PrevDecl;
3769  Specialization->setLocation(TemplateNameLoc);
3770  PrevDecl = nullptr;
3771  } else if (IsPartialSpecialization) {
3772  // Create a new class template partial specialization declaration node.
3774  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
3777  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
3778  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
3779  Converted, TemplateArgs);
3780 
3781  if (!PrevPartial)
3782  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
3783  Specialization = Partial;
3784 
3785  // If we are providing an explicit specialization of a member variable
3786  // template specialization, make a note of that.
3787  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
3788  PrevPartial->setMemberSpecialization();
3789 
3790  CheckTemplatePartialSpecialization(Partial);
3791  } else {
3792  // Create a new class template specialization declaration node for
3793  // this explicit specialization or friend declaration.
3794  Specialization = VarTemplateSpecializationDecl::Create(
3795  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
3796  VarTemplate, DI->getType(), DI, SC, Converted);
3797  Specialization->setTemplateArgsInfo(TemplateArgs);
3798 
3799  if (!PrevDecl)
3800  VarTemplate->AddSpecialization(Specialization, InsertPos);
3801  }
3802 
3803  // C++ [temp.expl.spec]p6:
3804  // If a template, a member template or the member of a class template is
3805  // explicitly specialized then that specialization shall be declared
3806  // before the first use of that specialization that would cause an implicit
3807  // instantiation to take place, in every translation unit in which such a
3808  // use occurs; no diagnostic is required.
3809  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
3810  bool Okay = false;
3811  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
3812  // Is there any previous explicit specialization declaration?
3814  Okay = true;
3815  break;
3816  }
3817  }
3818 
3819  if (!Okay) {
3820  SourceRange Range(TemplateNameLoc, RAngleLoc);
3821  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
3822  << Name << Range;
3823 
3824  Diag(PrevDecl->getPointOfInstantiation(),
3825  diag::note_instantiation_required_here)
3826  << (PrevDecl->getTemplateSpecializationKind() !=
3828  return true;
3829  }
3830  }
3831 
3832  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
3833  Specialization->setLexicalDeclContext(CurContext);
3834 
3835  // Add the specialization into its lexical context, so that it can
3836  // be seen when iterating through the list of declarations in that
3837  // context. However, specializations are not found by name lookup.
3838  CurContext->addDecl(Specialization);
3839 
3840  // Note that this is an explicit specialization.
3842 
3843  if (PrevDecl) {
3844  // Check that this isn't a redefinition of this specialization,
3845  // merging with previous declarations.
3846  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
3847  forRedeclarationInCurContext());
3848  PrevSpec.addDecl(PrevDecl);
3849  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
3850  } else if (Specialization->isStaticDataMember() &&
3851  Specialization->isOutOfLine()) {
3852  Specialization->setAccess(VarTemplate->getAccess());
3853  }
3854 
3855  // Link instantiations of static data members back to the template from
3856  // which they were instantiated.
3857  if (Specialization->isStaticDataMember())
3858  Specialization->setInstantiationOfStaticDataMember(
3859  VarTemplate->getTemplatedDecl(),
3860  Specialization->getSpecializationKind());
3861 
3862  return Specialization;
3863 }
3864 
3865 namespace {
3866 /// A partial specialization whose template arguments have matched
3867 /// a given template-id.
3868 struct PartialSpecMatchResult {
3870  TemplateArgumentList *Args;
3871 };
3872 } // end anonymous namespace
3873 
3874 DeclResult
3876  SourceLocation TemplateNameLoc,
3877  const TemplateArgumentListInfo &TemplateArgs) {
3878  assert(Template && "A variable template id without template?");
3879 
3880  // Check that the template argument list is well-formed for this template.
3882  if (CheckTemplateArgumentList(
3883  Template, TemplateNameLoc,
3884  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
3885  Converted))
3886  return true;
3887 
3888  // Find the variable template specialization declaration that
3889  // corresponds to these arguments.
3890  void *InsertPos = nullptr;
3891  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
3892  Converted, InsertPos)) {
3893  checkSpecializationVisibility(TemplateNameLoc, Spec);
3894  // If we already have a variable template specialization, return it.
3895  return Spec;
3896  }
3897 
3898  // This is the first time we have referenced this variable template
3899  // specialization. Create the canonical declaration and add it to
3900  // the set of specializations, based on the closest partial specialization
3901  // that it represents. That is,
3902  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
3904  Converted);
3905  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
3906  bool AmbiguousPartialSpec = false;
3907  typedef PartialSpecMatchResult MatchResult;
3909  SourceLocation PointOfInstantiation = TemplateNameLoc;
3910  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
3911  /*ForTakingAddress=*/false);
3912 
3913  // 1. Attempt to find the closest partial specialization that this
3914  // specializes, if any.
3915  // If any of the template arguments is dependent, then this is probably
3916  // a placeholder for an incomplete declarative context; which must be
3917  // complete by instantiation time. Thus, do not search through the partial
3918  // specializations yet.
3919  // TODO: Unify with InstantiateClassTemplateSpecialization()?
3920  // Perhaps better after unification of DeduceTemplateArguments() and
3921  // getMoreSpecializedPartialSpecialization().
3922  bool InstantiationDependent = false;
3924  TemplateArgs, InstantiationDependent)) {
3925 
3927  Template->getPartialSpecializations(PartialSpecs);
3928 
3929  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
3930  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
3931  TemplateDeductionInfo Info(FailedCandidates.getLocation());
3932 
3933  if (TemplateDeductionResult Result =
3934  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
3935  // Store the failed-deduction information for use in diagnostics, later.
3936  // TODO: Actually use the failed-deduction info?
3937  FailedCandidates.addCandidate().set(
3938  DeclAccessPair::make(Template, AS_public), Partial,
3939  MakeDeductionFailureInfo(Context, Result, Info));
3940  (void)Result;
3941  } else {
3942  Matched.push_back(PartialSpecMatchResult());
3943  Matched.back().Partial = Partial;
3944  Matched.back().Args = Info.take();
3945  }
3946  }
3947 
3948  if (Matched.size() >= 1) {
3949  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
3950  if (Matched.size() == 1) {
3951  // -- If exactly one matching specialization is found, the
3952  // instantiation is generated from that specialization.
3953  // We don't need to do anything for this.
3954  } else {
3955  // -- If more than one matching specialization is found, the
3956  // partial order rules (14.5.4.2) are used to determine
3957  // whether one of the specializations is more specialized
3958  // than the others. If none of the specializations is more
3959  // specialized than all of the other matching
3960  // specializations, then the use of the variable template is
3961  // ambiguous and the program is ill-formed.
3962  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
3963  PEnd = Matched.end();
3964  P != PEnd; ++P) {
3965  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
3966  PointOfInstantiation) ==
3967  P->Partial)
3968  Best = P;
3969  }
3970 
3971  // Determine if the best partial specialization is more specialized than
3972  // the others.
3973  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
3974  PEnd = Matched.end();
3975  P != PEnd; ++P) {
3976  if (P != Best && getMoreSpecializedPartialSpecialization(
3977  P->Partial, Best->Partial,
3978  PointOfInstantiation) != Best->Partial) {
3979  AmbiguousPartialSpec = true;
3980  break;
3981  }
3982  }
3983  }
3984 
3985  // Instantiate using the best variable template partial specialization.
3986  InstantiationPattern = Best->Partial;
3987  InstantiationArgs = Best->Args;
3988  } else {
3989  // -- If no match is found, the instantiation is generated
3990  // from the primary template.
3991  // InstantiationPattern = Template->getTemplatedDecl();
3992  }
3993  }
3994 
3995  // 2. Create the canonical declaration.
3996  // Note that we do not instantiate a definition until we see an odr-use
3997  // in DoMarkVarDeclReferenced().
3998  // FIXME: LateAttrs et al.?
3999  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4000  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4001  Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
4002  if (!Decl)
4003  return true;
4004 
4005  if (AmbiguousPartialSpec) {
4006  // Partial ordering did not produce a clear winner. Complain.
4007  Decl->setInvalidDecl();
4008  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4009  << Decl;
4010 
4011  // Print the matching partial specializations.
4012  for (MatchResult P : Matched)
4013  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4014  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4015  *P.Args);
4016  return true;
4017  }
4018 
4020  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4021  Decl->setInstantiationOf(D, InstantiationArgs);
4022 
4023  checkSpecializationVisibility(TemplateNameLoc, Decl);
4024 
4025  assert(Decl && "No variable template specialization?");
4026  return Decl;
4027 }
4028 
4029 ExprResult
4031  const DeclarationNameInfo &NameInfo,
4032  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4033  const TemplateArgumentListInfo *TemplateArgs) {
4034 
4035  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4036  *TemplateArgs);
4037  if (Decl.isInvalid())
4038  return ExprError();
4039 
4040  VarDecl *Var = cast<VarDecl>(Decl.get());
4041  if (!Var->getTemplateSpecializationKind())
4043  NameInfo.getLoc());
4044 
4045  // Build an ordinary singleton decl ref.
4046  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4047  /*FoundD=*/nullptr, TemplateArgs);
4048 }
4049 
4051  SourceLocation Loc) {
4052  Diag(Loc, diag::err_template_missing_args)
4053  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4054  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4055  Diag(TD->getLocation(), diag::note_template_decl_here)
4056  << TD->getTemplateParameters()->getSourceRange();
4057  }
4058 }
4059 
4061  SourceLocation TemplateKWLoc,
4062  LookupResult &R,
4063  bool RequiresADL,
4064  const TemplateArgumentListInfo *TemplateArgs) {
4065  // FIXME: Can we do any checking at this point? I guess we could check the
4066  // template arguments that we have against the template name, if the template
4067  // name refers to a single template. That's not a terribly common case,
4068  // though.
4069  // foo<int> could identify a single function unambiguously
4070  // This approach does NOT work, since f<int>(1);
4071  // gets resolved prior to resorting to overload resolution
4072  // i.e., template<class T> void f(double);
4073  // vs template<class T, class U> void f(U);
4074 
4075  // These should be filtered out by our callers.
4076  assert(!R.empty() && "empty lookup results when building templateid");
4077  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4078 
4079  // Non-function templates require a template argument list.
4080  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4081  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4082  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4083  return ExprError();
4084  }
4085  }
4086 
4087  auto AnyDependentArguments = [&]() -> bool {
4088  bool InstantiationDependent;
4089  return TemplateArgs &&
4091  *TemplateArgs, InstantiationDependent);
4092  };
4093 
4094  // In C++1y, check variable template ids.
4095  if (R.getAsSingle<VarTemplateDecl>() && !AnyDependentArguments()) {
4096  return CheckVarTemplateId(SS, R.getLookupNameInfo(),
4098  TemplateKWLoc, TemplateArgs);
4099  }
4100 
4101  // We don't want lookup warnings at this point.
4102  R.suppressDiagnostics();
4103 
4106  SS.getWithLocInContext(Context),
4107  TemplateKWLoc,
4108  R.getLookupNameInfo(),
4109  RequiresADL, TemplateArgs,
4110  R.begin(), R.end());
4111 
4112  return ULE;
4113 }
4114 
4115 // We actually only call this from template instantiation.
4116 ExprResult
4118  SourceLocation TemplateKWLoc,
4119  const DeclarationNameInfo &NameInfo,
4120  const TemplateArgumentListInfo *TemplateArgs) {
4121 
4122  assert(TemplateArgs || TemplateKWLoc.isValid());
4123  DeclContext *DC;
4124  if (!(DC = computeDeclContext(SS, false)) ||
4125  DC->isDependentContext() ||
4126  RequireCompleteDeclContext(SS, DC))
4127  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4128 
4129  bool MemberOfUnknownSpecialization;
4130  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4131  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4132  /*Entering*/false, MemberOfUnknownSpecialization,
4133  TemplateKWLoc))
4134  return ExprError();
4135 
4136  if (R.isAmbiguous())
4137  return ExprError();
4138 
4139  if (R.empty()) {
4140  Diag(NameInfo.getLoc(), diag::err_no_member)
4141  << NameInfo.getName() << DC << SS.getRange();
4142  return ExprError();
4143  }
4144 
4145  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4146  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4147  << SS.getScopeRep()
4148  << NameInfo.getName().getAsString() << SS.getRange();
4149  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4150  return ExprError();
4151  }
4152 
4153  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4154 }
4155 
4156 /// Form a dependent template name.
4157 ///
4158 /// This action forms a dependent template name given the template
4159 /// name and its (presumably dependent) scope specifier. For
4160 /// example, given "MetaFun::template apply", the scope specifier \p
4161 /// SS will be "MetaFun::", \p TemplateKWLoc contains the location
4162 /// of the "template" keyword, and "apply" is the \p Name.
4164  CXXScopeSpec &SS,
4165  SourceLocation TemplateKWLoc,
4166  const UnqualifiedId &Name,
4167  ParsedType ObjectType,
4168  bool EnteringContext,
4169  TemplateTy &Result,
4170  bool AllowInjectedClassName) {
4171  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4172  Diag(TemplateKWLoc,
4173  getLangOpts().CPlusPlus11 ?
4174  diag::warn_cxx98_compat_template_outside_of_template :
4175  diag::ext_template_outside_of_template)
4176  << FixItHint::CreateRemoval(TemplateKWLoc);
4177 
4178  DeclContext *LookupCtx = nullptr;
4179  if (SS.isSet())
4180  LookupCtx = computeDeclContext(SS, EnteringContext);
4181  if (!LookupCtx && ObjectType)
4182  LookupCtx = computeDeclContext(ObjectType.get());
4183  if (LookupCtx) {
4184  // C++0x [temp.names]p5:
4185  // If a name prefixed by the keyword template is not the name of
4186  // a template, the program is ill-formed. [Note: the keyword
4187  // template may not be applied to non-template members of class
4188  // templates. -end note ] [ Note: as is the case with the
4189  // typename prefix, the template prefix is allowed in cases
4190  // where it is not strictly necessary; i.e., when the
4191  // nested-name-specifier or the expression on the left of the ->
4192  // or . is not dependent on a template-parameter, or the use
4193  // does not appear in the scope of a template. -end note]
4194  //
4195  // Note: C++03 was more strict here, because it banned the use of
4196  // the "template" keyword prior to a template-name that was not a
4197  // dependent name. C++ DR468 relaxed this requirement (the
4198  // "template" keyword is now permitted). We follow the C++0x
4199  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4200  bool MemberOfUnknownSpecialization;
4201  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4202  ObjectType, EnteringContext, Result,
4203  MemberOfUnknownSpecialization);
4204  if (TNK == TNK_Non_template && MemberOfUnknownSpecialization) {
4205  // This is a dependent template. Handle it below.
4206  } else if (TNK == TNK_Non_template) {
4207  // Do the lookup again to determine if this is a "nothing found" case or
4208  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4209  // need to do this.
4210  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4211  LookupResult R(*this, DNI.getName(), Name.getLocStart(),
4212  LookupOrdinaryName);
4213  bool MOUS;
4214  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext,
4215  MOUS, TemplateKWLoc))
4216  Diag(Name.getLocStart(), diag::err_no_member)
4217  << DNI.getName() << LookupCtx << SS.getRange();
4218  return TNK_Non_template;
4219  } else {
4220  // We found something; return it.
4221  auto *LookupRD = dyn_cast<CXXRecordDecl>(LookupCtx);
4222  if (!AllowInjectedClassName && SS.isSet() && LookupRD &&
4224  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4225  // C++14 [class.qual]p2:
4226  // In a lookup in which function names are not ignored and the
4227  // nested-name-specifier nominates a class C, if the name specified
4228  // [...] is the injected-class-name of C, [...] the name is instead
4229  // considered to name the constructor
4230  //
4231  // We don't get here if naming the constructor would be valid, so we
4232  // just reject immediately and recover by treating the
4233  // injected-class-name as naming the template.
4234  Diag(Name.getLocStart(),
4235  diag::ext_out_of_line_qualified_id_type_names_constructor)
4236  << Name.Identifier << 0 /*injected-class-name used as template name*/
4237  << 1 /*'template' keyword was used*/;
4238  }
4239  return TNK;
4240  }
4241  }
4242 
4243  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4244 
4245  switch (Name.getKind()) {
4247  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4248  Name.Identifier));
4250 
4252  Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
4254  return TNK_Function_template;
4255 
4257  llvm_unreachable("literal operator id cannot have a dependent scope");
4258 
4259  default:
4260  break;
4261  }
4262 
4263  Diag(Name.getLocStart(),
4264  diag::err_template_kw_refers_to_non_template)
4265  << GetNameFromUnqualifiedId(Name).getName()
4266  << Name.getSourceRange()
4267  << TemplateKWLoc;
4268  return TNK_Non_template;
4269 }
4270 
4272  TemplateArgumentLoc &AL,
4273  SmallVectorImpl<TemplateArgument> &Converted) {
4274  const TemplateArgument &Arg = AL.getArgument();
4275  QualType ArgType;
4276  TypeSourceInfo *TSI = nullptr;
4277 
4278  // Check template type parameter.
4279  switch(Arg.getKind()) {
4281  // C++ [temp.arg.type]p1:
4282  // A template-argument for a template-parameter which is a
4283  // type shall be a type-id.
4284  ArgType = Arg.getAsType();
4285  TSI = AL.getTypeSourceInfo();
4286  break;
4289  // We have a template type parameter but the template argument
4290  // is a template without any arguments.
4291  SourceRange SR = AL.getSourceRange();
4293  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4294  return true;
4295  }
4297  // We have a template type parameter but the template argument is an
4298  // expression; see if maybe it is missing the "typename" keyword.
4299  CXXScopeSpec SS;
4300  DeclarationNameInfo NameInfo;
4301 
4302  if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
4303  SS.Adopt(ArgExpr->getQualifierLoc());
4304  NameInfo = ArgExpr->getNameInfo();
4305  } else if (DependentScopeDeclRefExpr *ArgExpr =
4306  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4307  SS.Adopt(ArgExpr->getQualifierLoc());
4308  NameInfo = ArgExpr->getNameInfo();
4309  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4310  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4311  if (ArgExpr->isImplicitAccess()) {
4312  SS.Adopt(ArgExpr->getQualifierLoc());
4313  NameInfo = ArgExpr->getMemberNameInfo();
4314  }
4315  }
4316 
4317  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4318  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4319  LookupParsedName(Result, CurScope, &SS);
4320 
4321  if (Result.getAsSingle<TypeDecl>() ||
4322  Result.getResultKind() ==
4324  // Suggest that the user add 'typename' before the NNS.
4325  SourceLocation Loc = AL.getSourceRange().getBegin();
4326  Diag(Loc, getLangOpts().MSVCCompat
4327  ? diag::ext_ms_template_type_arg_missing_typename
4328  : diag::err_template_arg_must_be_type_suggest)
4329  << FixItHint::CreateInsertion(Loc, "typename ");
4330  Diag(Param->getLocation(), diag::note_template_param_here);
4331 
4332  // Recover by synthesizing a type using the location information that we
4333  // already have.
4334  ArgType =
4335  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4336  TypeLocBuilder TLB;
4337  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4338  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4339  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4340  TL.setNameLoc(NameInfo.getLoc());
4341  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4342 
4343  // Overwrite our input TemplateArgumentLoc so that we can recover
4344  // properly.
4345  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
4347 
4348  break;
4349  }
4350  }
4351  // fallthrough
4352  LLVM_FALLTHROUGH;
4353  }
4354  default: {
4355  // We have a template type parameter but the template argument
4356  // is not a type.
4357  SourceRange SR = AL.getSourceRange();
4358  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
4359  Diag(Param->getLocation(), diag::note_template_param_here);
4360 
4361  return true;
4362  }
4363  }
4364 
4365  if (CheckTemplateArgument(Param, TSI))
4366  return true;
4367 
4368  // Add the converted template type argument.
4369  ArgType = Context.getCanonicalType(ArgType);
4370 
4371  // Objective-C ARC:
4372  // If an explicitly-specified template argument type is a lifetime type
4373  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
4374  if (getLangOpts().ObjCAutoRefCount &&
4375  ArgType->isObjCLifetimeType() &&
4376  !ArgType.getObjCLifetime()) {
4377  Qualifiers Qs;
4379  ArgType = Context.getQualifiedType(ArgType, Qs);
4380  }
4381 
4382  Converted.push_back(TemplateArgument(ArgType));
4383  return false;
4384 }
4385 
4386 /// Substitute template arguments into the default template argument for
4387 /// the given template type parameter.
4388 ///
4389 /// \param SemaRef the semantic analysis object for which we are performing
4390 /// the substitution.
4391 ///
4392 /// \param Template the template that we are synthesizing template arguments
4393 /// for.
4394 ///
4395 /// \param TemplateLoc the location of the template name that started the
4396 /// template-id we are checking.
4397 ///
4398 /// \param RAngleLoc the location of the right angle bracket ('>') that
4399 /// terminates the template-id.
4400 ///
4401 /// \param Param the template template parameter whose default we are
4402 /// substituting into.
4403 ///
4404 /// \param Converted the list of template arguments provided for template
4405 /// parameters that precede \p Param in the template parameter list.
4406 /// \returns the substituted template argument, or NULL if an error occurred.
4407 static TypeSourceInfo *
4409  TemplateDecl *Template,
4410  SourceLocation TemplateLoc,
4411  SourceLocation RAngleLoc,
4412  TemplateTypeParmDecl *Param,
4413  SmallVectorImpl<TemplateArgument> &Converted) {
4414  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
4415 
4416  // If the argument type is dependent, instantiate it now based
4417  // on the previously-computed template arguments.
4418  if (ArgType->getType()->isDependentType()) {
4419  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4420  Param, Template, Converted,
4421  SourceRange(TemplateLoc, RAngleLoc));
4422  if (Inst.isInvalid())
4423  return nullptr;
4424 
4425  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4426 
4427  // Only substitute for the innermost template argument list.
4428  MultiLevelTemplateArgumentList TemplateArgLists;
4429  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4430  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4431  TemplateArgLists.addOuterTemplateArguments(None);
4432 
4433  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4434  ArgType =
4435  SemaRef.SubstType(ArgType, TemplateArgLists,
4436  Param->getDefaultArgumentLoc(), Param->getDeclName());
4437  }
4438 
4439  return ArgType;
4440 }
4441 
4442 /// Substitute template arguments into the default template argument for
4443 /// the given non-type template parameter.
4444 ///
4445 /// \param SemaRef the semantic analysis object for which we are performing
4446 /// the substitution.
4447 ///
4448 /// \param Template the template that we are synthesizing template arguments
4449 /// for.
4450 ///
4451 /// \param TemplateLoc the location of the template name that started the
4452 /// template-id we are checking.
4453 ///
4454 /// \param RAngleLoc the location of the right angle bracket ('>') that
4455 /// terminates the template-id.
4456 ///
4457 /// \param Param the non-type template parameter whose default we are
4458 /// substituting into.
4459 ///
4460 /// \param Converted the list of template arguments provided for template
4461 /// parameters that precede \p Param in the template parameter list.
4462 ///
4463 /// \returns the substituted template argument, or NULL if an error occurred.
4464 static ExprResult
4466  TemplateDecl *Template,
4467  SourceLocation TemplateLoc,
4468  SourceLocation RAngleLoc,
4469  NonTypeTemplateParmDecl *Param,
4470  SmallVectorImpl<TemplateArgument> &Converted) {
4471  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
4472  Param, Template, Converted,
4473  SourceRange(TemplateLoc, RAngleLoc));
4474  if (Inst.isInvalid())
4475  return ExprError();
4476 
4477  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4478 
4479  // Only substitute for the innermost template argument list.
4480  MultiLevelTemplateArgumentList TemplateArgLists;
4481  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4482  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4483  TemplateArgLists.addOuterTemplateArguments(None);
4484 
4485  EnterExpressionEvaluationContext ConstantEvaluated(
4487  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
4488 }
4489 
4490 /// Substitute template arguments into the default template argument for
4491 /// the given template template parameter.
4492 ///
4493 /// \param SemaRef the semantic analysis object for which we are performing
4494 /// the substitution.
4495 ///
4496 /// \param Template the template that we are synthesizing template arguments
4497 /// for.
4498 ///
4499 /// \param TemplateLoc the location of the template name that started the
4500 /// template-id we are checking.
4501 ///
4502 /// \param RAngleLoc the location of the right angle bracket ('>') that
4503 /// terminates the template-id.
4504 ///
4505 /// \param Param the template template parameter whose default we are
4506 /// substituting into.
4507 ///
4508 /// \param Converted the list of template arguments provided for template
4509 /// parameters that precede \p Param in the template parameter list.
4510 ///
4511 /// \param QualifierLoc Will be set to the nested-name-specifier (with
4512 /// source-location information) that precedes the template name.
4513 ///
4514 /// \returns the substituted template argument, or NULL if an error occurred.
4515 static TemplateName
4517  TemplateDecl *Template,
4518  SourceLocation TemplateLoc,
4519  SourceLocation RAngleLoc,
4520  TemplateTemplateParmDecl *Param,
4522  NestedNameSpecifierLoc &QualifierLoc) {
4524  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
4525  SourceRange(TemplateLoc, RAngleLoc));
4526  if (Inst.isInvalid())
4527  return TemplateName();
4528 
4529  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4530 
4531  // Only substitute for the innermost template argument list.
4532  MultiLevelTemplateArgumentList TemplateArgLists;
4533  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
4534  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
4535  TemplateArgLists.addOuterTemplateArguments(None);
4536 
4537  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
4538  // Substitute into the nested-name-specifier first,
4539  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
4540  if (QualifierLoc) {
4541  QualifierLoc =
4542  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
4543  if (!QualifierLoc)
4544  return TemplateName();
4545  }
4546 
4547  return SemaRef.SubstTemplateName(
4548  QualifierLoc,
4551  TemplateArgLists);
4552 }
4553 
4554 /// If the given template parameter has a default template
4555 /// argument, substitute into that default template argument and
4556 /// return the corresponding template argument.
4559  SourceLocation TemplateLoc,
4560  SourceLocation RAngleLoc,
4561  Decl *Param,
4563  &Converted,
4564  bool &HasDefaultArg) {
4565  HasDefaultArg = false;
4566 
4567  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
4568  if (!hasVisibleDefaultArgument(TypeParm))
4569  return TemplateArgumentLoc();
4570 
4571  HasDefaultArg = true;
4572  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
4573  TemplateLoc,
4574  RAngleLoc,
4575  TypeParm,
4576  Converted);
4577  if (DI)
4578  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
4579 
4580  return TemplateArgumentLoc();
4581  }
4582 
4583  if (NonTypeTemplateParmDecl *NonTypeParm
4584  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4585  if (!hasVisibleDefaultArgument(NonTypeParm))
4586  return TemplateArgumentLoc();
4587 
4588  HasDefaultArg = true;
4589  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
4590  TemplateLoc,
4591  RAngleLoc,
4592  NonTypeParm,
4593  Converted);
4594  if (Arg.isInvalid())
4595  return TemplateArgumentLoc();
4596 
4597  Expr *ArgE = Arg.getAs<Expr>();
4598  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
4599  }
4600 
4601  TemplateTemplateParmDecl *TempTempParm
4602  = cast<TemplateTemplateParmDecl>(Param);
4603  if (!hasVisibleDefaultArgument(TempTempParm))
4604  return TemplateArgumentLoc();
4605 
4606  HasDefaultArg = true;
4607  NestedNameSpecifierLoc QualifierLoc;
4608  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
4609  TemplateLoc,
4610  RAngleLoc,
4611  TempTempParm,
4612  Converted,
4613  QualifierLoc);
4614  if (TName.isNull())
4615  return TemplateArgumentLoc();
4616 
4617  return TemplateArgumentLoc(TemplateArgument(TName),
4618  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
4619  TempTempParm->getDefaultArgument().getTemplateNameLoc());
4620 }
4621 
4622 /// Convert a template-argument that we parsed as a type into a template, if
4623 /// possible. C++ permits injected-class-names to perform dual service as
4624 /// template template arguments and as template type arguments.
4626  // Extract and step over any surrounding nested-name-specifier.
4627  NestedNameSpecifierLoc QualLoc;
4628  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
4629  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
4630  return TemplateArgumentLoc();
4631 
4632  QualLoc = ETLoc.getQualifierLoc();
4633  TLoc = ETLoc.getNamedTypeLoc();
4634  }
4635 
4636  // If this type was written as an injected-class-name, it can be used as a
4637  // template template argument.
4638  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
4639  return TemplateArgumentLoc(InjLoc.getTypePtr()->getTemplateName(),
4640  QualLoc, InjLoc.getNameLoc());
4641 
4642  // If this type was written as an injected-class-name, it may have been
4643  // converted to a RecordType during instantiation. If the RecordType is
4644  // *not* wrapped in a TemplateSpecializationType and denotes a class
4645  // template specialization, it must have come from an injected-class-name.
4646  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
4647  if (auto *CTSD =
4648  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
4649  return TemplateArgumentLoc(TemplateName(CTSD->getSpecializedTemplate()),
4650  QualLoc, RecLoc.getNameLoc());
4651 
4652  return TemplateArgumentLoc();
4653 }
4654 
4655 /// Check that the given template argument corresponds to the given
4656 /// template parameter.
4657 ///
4658 /// \param Param The template parameter against which the argument will be
4659 /// checked.
4660 ///
4661 /// \param Arg The template argument, which may be updated due to conversions.
4662 ///
4663 /// \param Template The template in which the template argument resides.
4664 ///
4665 /// \param TemplateLoc The location of the template name for the template
4666 /// whose argument list we're matching.
4667 ///
4668 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
4669 /// the template argument list.
4670 ///
4671 /// \param ArgumentPackIndex The index into the argument pack where this
4672 /// argument will be placed. Only valid if the parameter is a parameter pack.
4673 ///
4674 /// \param Converted The checked, converted argument will be added to the
4675 /// end of this small vector.
4676 ///
4677 /// \param CTAK Describes how we arrived at this particular template argument:
4678 /// explicitly written, deduced, etc.
4679 ///
4680 /// \returns true on error, false otherwise.
4682  TemplateArgumentLoc &Arg,
4683  NamedDecl *Template,
4684  SourceLocation TemplateLoc,
4685  SourceLocation RAngleLoc,
4686  unsigned ArgumentPackIndex,
4689  // Check template type parameters.
4690  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
4691  return CheckTemplateTypeArgument(TTP, Arg, Converted);
4692 
4693  // Check non-type template parameters.
4694  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4695  // Do substitution on the type of the non-type template parameter
4696  // with the template arguments we've seen thus far. But if the
4697  // template has a dependent context then we cannot substitute yet.
4698  QualType NTTPType = NTTP->getType();
4699  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
4700  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
4701 
4702  // FIXME: Do we need to substitute into parameters here if they're
4703  // instantiation-dependent but not dependent?
4704  if (NTTPType->isDependentType() &&
4705  !isa<TemplateTemplateParmDecl>(Template) &&
4706  !Template->getDeclContext()->isDependentContext()) {
4707  // Do substitution on the type of the non-type template parameter.
4708  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4709  NTTP, Converted,
4710  SourceRange(TemplateLoc, RAngleLoc));
4711  if (Inst.isInvalid())
4712  return true;
4713 
4715  Converted);
4716  NTTPType = SubstType(NTTPType,
4717  MultiLevelTemplateArgumentList(TemplateArgs),
4718  NTTP->getLocation(),
4719  NTTP->getDeclName());
4720  // If that worked, check the non-type template parameter type
4721  // for validity.
4722  if (!NTTPType.isNull())
4723  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
4724  NTTP->getLocation());
4725  if (NTTPType.isNull())
4726  return true;
4727  }
4728 
4729  switch (Arg.getArgument().getKind()) {
4731  llvm_unreachable("Should never see a NULL template argument here");
4732 
4734  TemplateArgument Result;
4735  unsigned CurSFINAEErrors = NumSFINAEErrors;
4736  ExprResult Res =
4737  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
4738  Result, CTAK);
4739  if (Res.isInvalid())
4740  return true;
4741  // If the current template argument causes an error, give up now.
4742  if (CurSFINAEErrors < NumSFINAEErrors)
4743  return true;
4744 
4745  // If the resulting expression is new, then use it in place of the
4746  // old expression in the template argument.
4747  if (Res.get() != Arg.getArgument().getAsExpr()) {
4748  TemplateArgument TA(Res.get());
4749  Arg = TemplateArgumentLoc(TA, Res.get());
4750  }
4751 
4752  Converted.push_back(Result);
4753  break;
4754  }
4755 
4759  // We've already checked this template argument, so just copy
4760  // it to the list of converted arguments.
4761  Converted.push_back(Arg.getArgument());
4762  break;
4763 
4766  // We were given a template template argument. It may not be ill-formed;
4767  // see below.
4768  if (DependentTemplateName *DTN
4771  // We have a template argument such as \c T::template X, which we
4772  // parsed as a template template argument. However, since we now
4773  // know that we need a non-type template argument, convert this
4774  // template name into an expression.
4775 
4776  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
4777  Arg.getTemplateNameLoc());
4778 
4779  CXXScopeSpec SS;
4780  SS.Adopt(Arg.getTemplateQualifierLoc());
4781  // FIXME: the template-template arg was a DependentTemplateName,
4782  // so it was provided with a template keyword. However, its source
4783  // location is not stored in the template argument structure.
4784  SourceLocation TemplateKWLoc;
4786  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
4787  nullptr);
4788 
4789  // If we parsed the template argument as a pack expansion, create a
4790  // pack expansion expression.
4792  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
4793  if (E.isInvalid())
4794  return true;
4795  }
4796 
4797  TemplateArgument Result;
4798  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
4799  if (E.isInvalid())
4800  return true;
4801 
4802  Converted.push_back(Result);
4803  break;
4804  }
4805 
4806  // We have a template argument that actually does refer to a class
4807  // template, alias template, or template template parameter, and
4808  // therefore cannot be a non-type template argument.
4809  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
4810  << Arg.getSourceRange();
4811 
4812  Diag(Param->getLocation(), diag::note_template_param_here);
4813  return true;
4814 
4815  case TemplateArgument::Type: {
4816  // We have a non-type template parameter but the template
4817  // argument is a type.
4818 
4819  // C++ [temp.arg]p2:
4820  // In a template-argument, an ambiguity between a type-id and
4821  // an expression is resolved to a type-id, regardless of the
4822  // form of the corresponding template-parameter.
4823  //
4824  // We warn specifically about this case, since it can be rather
4825  // confusing for users.
4826  QualType T = Arg.getArgument().getAsType();
4827  SourceRange SR = Arg.getSourceRange();
4828  if (T->isFunctionType())
4829  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
4830  else
4831  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
4832  Diag(Param->getLocation(), diag::note_template_param_here);
4833  return true;
4834  }
4835 
4837  llvm_unreachable("Caller must expand template argument packs");
4838  }
4839 
4840  return false;
4841  }
4842 
4843 
4844  // Check template template parameters.
4845  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
4846 
4847  TemplateParameterList *Params = TempParm->getTemplateParameters();
4848  if (TempParm->isExpandedParameterPack())
4849  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
4850 
4851  // Substitute into the template parameter list of the template
4852  // template parameter, since previously-supplied template arguments
4853  // may appear within the template template parameter.
4854  //
4855  // FIXME: Skip this if the parameters aren't instantiation-dependent.
4856  {
4857  // Set up a template instantiation context.
4859  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
4860  TempParm, Converted,
4861  SourceRange(TemplateLoc, RAngleLoc));
4862  if (Inst.isInvalid())
4863  return true;
4864 
4865  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
4866  Params = SubstTemplateParams(Params, CurContext,
4867  MultiLevelTemplateArgumentList(TemplateArgs));
4868  if (!Params)
4869  return true;
4870  }
4871 
4872  // C++1z [temp.local]p1: (DR1004)
4873  // When [the injected-class-name] is used [...] as a template-argument for
4874  // a template template-parameter [...] it refers to the class template
4875  // itself.
4876  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
4878  Arg.getTypeSourceInfo()->getTypeLoc());
4879  if (!ConvertedArg.getArgument().isNull())
4880  Arg = ConvertedArg;
4881  }
4882 
4883  switch (Arg.getArgument().getKind()) {
4885  llvm_unreachable("Should never see a NULL template argument here");
4886 
4889  if (CheckTemplateTemplateArgument(Params, Arg))
4890  return true;
4891 
4892  Converted.push_back(Arg.getArgument());
4893  break;
4894 
4897  // We have a template template parameter but the template
4898  // argument does not refer to a template.
4899  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
4900  << getLangOpts().CPlusPlus11;
4901  return true;
4902 
4904  llvm_unreachable("Declaration argument with template template parameter");
4906  llvm_unreachable("Integral argument with template template parameter");
4908  llvm_unreachable("Null pointer argument with template template parameter");
4909 
4911  llvm_unreachable("Caller must expand template argument packs");
4912  }
4913 
4914  return false;
4915 }
4916 
4917 /// Check whether the template parameter is a pack expansion, and if so,
4918 /// determine the number of parameters produced by that expansion. For instance:
4919 ///
4920 /// \code
4921 /// template<typename ...Ts> struct A {
4922 /// template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
4923 /// };
4924 /// \endcode
4925 ///
4926 /// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
4927 /// is not a pack expansion, so returns an empty Optional.
4929  if (NonTypeTemplateParmDecl *NTTP
4930  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
4931  if (NTTP->isExpandedParameterPack())
4932  return NTTP->getNumExpansionTypes();
4933  }
4934 
4935  if (TemplateTemplateParmDecl *TTP
4936  = dyn_cast<TemplateTemplateParmDecl>(Param)) {
4937  if (TTP->isExpandedParameterPack())
4938  return TTP->getNumExpansionTemplateParameters();
4939  }
4940 
4941  return None;
4942 }
4943 
4944 /// Diagnose a missing template argument.
4945 template<typename TemplateParmDecl>
4947  TemplateDecl *TD,
4948  const TemplateParmDecl *D,
4949  TemplateArgumentListInfo &Args) {
4950  // Dig out the most recent declaration of the template parameter; there may be
4951  // declarations of the template that are more recent than TD.
4952  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
4953  ->getTemplateParameters()
4954  ->getParam(D->getIndex()));
4955 
4956  // If there's a default argument that's not visible, diagnose that we're
4957  // missing a module import.
4959  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
4960  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
4961  D->getDefaultArgumentLoc(), Modules,
4963  /*Recover*/true);
4964  return true;
4965  }
4966 
4967  // FIXME: If there's a more recent default argument that *is* visible,
4968  // diagnose that it was declared too late.
4969 
4971 
4972  S.Diag(Loc, diag::err_template_arg_list_different_arity)
4973  << /*not enough args*/0
4975  << TD;
4976  S.Diag(TD->getLocation(), diag::note_template_decl_here)
4977  << Params->getSourceRange();
4978  return true;
4979 }
4980 
4981 /// Check that the given template argument list is well-formed
4982 /// for specializing the given template.
4984  TemplateDecl *Template, SourceLocation TemplateLoc,
4985  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
4987  bool UpdateArgsWithConversions) {
4988  // Make a copy of the template arguments for processing. Only make the
4989  // changes at the end when successful in matching the arguments to the
4990  // template.
4991  TemplateArgumentListInfo NewArgs = TemplateArgs;
4992 
4993  // Make sure we get the template parameter list from the most
4994  // recentdeclaration, since that is the only one that has is guaranteed to
4995  // have all the default template argument information.
4996  TemplateParameterList *Params =
4997  cast<TemplateDecl>(Template->getMostRecentDecl())
4998  ->getTemplateParameters();
4999 
5000  SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
5001 
5002  // C++ [temp.arg]p1:
5003  // [...] The type and form of each template-argument specified in
5004  // a template-id shall match the type and form specified for the
5005  // corresponding parameter declared by the template in its
5006  // template-parameter-list.
5007  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
5008  SmallVector<TemplateArgument, 2> ArgumentPack;
5009  unsigned ArgIdx = 0, NumArgs = NewArgs.size();
5010  LocalInstantiationScope InstScope(*this, true);
5011  for (TemplateParameterList::iterator Param = Params->begin(),
5012  ParamEnd = Params->end();
5013  Param != ParamEnd; /* increment in loop */) {
5014  // If we have an expanded parameter pack, make sure we don't have too
5015  // many arguments.
5016  if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
5017  if (*Expansions == ArgumentPack.size()) {
5018  // We're done with this parameter pack. Pack up its arguments and add
5019  // them to the list.
5020  Converted.push_back(
5021  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5022  ArgumentPack.clear();
5023 
5024  // This argument is assigned to the next parameter.
5025  ++Param;
5026  continue;
5027  } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
5028  // Not enough arguments for this parameter pack.
5029  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5030  << /*not enough args*/0
5031  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5032  << Template;
5033  Diag(Template->getLocation(), diag::note_template_decl_here)
5034  << Params->getSourceRange();
5035  return true;
5036  }
5037  }
5038 
5039  if (ArgIdx < NumArgs) {
5040  // Check the template argument we were given.
5041  if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
5042  TemplateLoc, RAngleLoc,
5043  ArgumentPack.size(), Converted))
5044  return true;
5045 
5046  bool PackExpansionIntoNonPack =
5047  NewArgs[ArgIdx].getArgument().isPackExpansion() &&
5048  (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
5049  if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
5050  // Core issue 1430: we have a pack expansion as an argument to an
5051  // alias template, and it's not part of a parameter pack. This
5052  // can't be canonicalized, so reject it now.
5053  Diag(NewArgs[ArgIdx].getLocation(),
5054  diag::err_alias_template_expansion_into_fixed_list)
5055  << NewArgs[ArgIdx].getSourceRange();
5056  Diag((*Param)->getLocation(), diag::note_template_param_here);
5057  return true;
5058  }
5059 
5060  // We're now done with this argument.
5061  ++ArgIdx;
5062 
5063  if ((*Param)->isTemplateParameterPack()) {
5064  // The template parameter was a template parameter pack, so take the
5065  // deduced argument and place it on the argument pack. Note that we
5066  // stay on the same template parameter so that we can deduce more
5067  // arguments.
5068  ArgumentPack.push_back(Converted.pop_back_val());
5069  } else {
5070  // Move to the next template parameter.
5071  ++Param;
5072  }
5073 
5074  // If we just saw a pack expansion into a non-pack, then directly convert
5075  // the remaining arguments, because we don't know what parameters they'll
5076  // match up with.
5077  if (PackExpansionIntoNonPack) {
5078  if (!ArgumentPack.empty()) {
5079  // If we were part way through filling in an expanded parameter pack,
5080  // fall back to just producing individual arguments.
5081  Converted.insert(Converted.end(),
5082  ArgumentPack.begin(), ArgumentPack.end());
5083  ArgumentPack.clear();
5084  }
5085 
5086  while (ArgIdx < NumArgs) {
5087  Converted.push_back(NewArgs[ArgIdx].getArgument());
5088  ++ArgIdx;
5089  }
5090 
5091  return false;
5092  }
5093 
5094  continue;
5095  }
5096 
5097  // If we're checking a partial template argument list, we're done.
5098  if (PartialTemplateArgs) {
5099  if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
5100  Converted.push_back(
5101  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5102 
5103  return false;
5104  }
5105 
5106  // If we have a template parameter pack with no more corresponding
5107  // arguments, just break out now and we'll fill in the argument pack below.
5108  if ((*Param)->isTemplateParameterPack()) {
5109  assert(!getExpandedPackSize(*Param) &&
5110  "Should have dealt with this already");
5111 
5112  // A non-expanded parameter pack before the end of the parameter list
5113  // only occurs for an ill-formed template parameter list, unless we've
5114  // got a partial argument list for a function template, so just bail out.
5115  if (Param + 1 != ParamEnd)
5116  return true;
5117 
5118  Converted.push_back(
5119  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5120  ArgumentPack.clear();
5121 
5122  ++Param;
5123  continue;
5124  }
5125 
5126  // Check whether we have a default argument.
5127  TemplateArgumentLoc Arg;
5128 
5129  // Retrieve the default template argument from the template
5130  // parameter. For each kind of template parameter, we substitute the
5131  // template arguments provided thus far and any "outer" template arguments
5132  // (when the template parameter was part of a nested template) into
5133  // the default argument.
5134  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
5135  if (!hasVisibleDefaultArgument(TTP))
5136  return diagnoseMissingArgument(*this, TemplateLoc, Template, TTP,
5137  NewArgs);
5138 
5140  Template,
5141  TemplateLoc,
5142  RAngleLoc,
5143  TTP,
5144  Converted);
5145  if (!ArgType)
5146  return true;
5147 
5148  Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
5149  ArgType);
5150  } else if (NonTypeTemplateParmDecl *NTTP
5151  = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
5152  if (!hasVisibleDefaultArgument(NTTP))
5153  return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
5154  NewArgs);
5155 
5156  ExprResult E = SubstDefaultTemplateArgument(*this, Template,
5157  TemplateLoc,
5158  RAngleLoc,
5159  NTTP,
5160  Converted);
5161  if (E.isInvalid())
5162  return true;
5163 
5164  Expr *Ex = E.getAs<Expr>();
5165  Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
5166  } else {
5167  TemplateTemplateParmDecl *TempParm
5168  = cast<TemplateTemplateParmDecl>(*Param);
5169 
5170  if (!hasVisibleDefaultArgument(TempParm))
5171  return diagnoseMissingArgument(*this, TemplateLoc, Template, TempParm,
5172  NewArgs);
5173 
5174  NestedNameSpecifierLoc QualifierLoc;
5175  TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
5176  TemplateLoc,
5177  RAngleLoc,
5178  TempParm,
5179  Converted,
5180  QualifierLoc);
5181  if (Name.isNull())
5182  return true;
5183 
5184  Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
5185  TempParm->getDefaultArgument().getTemplateNameLoc());
5186  }
5187 
5188  // Introduce an instantiation record that describes where we are using
5189  // the default template argument. We're not actually instantiating a
5190  // template here, we just create this object to put a note into the
5191  // context stack.
5192  InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
5193  SourceRange(TemplateLoc, RAngleLoc));
5194  if (Inst.isInvalid())
5195  return true;
5196 
5197  // Check the default template argument.
5198  if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
5199  RAngleLoc, 0, Converted))
5200  return true;
5201 
5202  // Core issue 150 (assumed resolution): if this is a template template
5203  // parameter, keep track of the default template arguments from the
5204  // template definition.
5205  if (isTemplateTemplateParameter)
5206  NewArgs.addArgument(Arg);
5207 
5208  // Move to the next template parameter and argument.
5209  ++Param;
5210  ++ArgIdx;
5211  }
5212 
5213  // If we're performing a partial argument substitution, allow any trailing
5214  // pack expansions; they might be empty. This can happen even if
5215  // PartialTemplateArgs is false (the list of arguments is complete but
5216  // still dependent).
5217  if (ArgIdx < NumArgs && CurrentInstantiationScope &&
5218  CurrentInstantiationScope->getPartiallySubstitutedPack()) {
5219  while (ArgIdx < NumArgs && NewArgs[ArgIdx].getArgument().isPackExpansion())
5220  Converted.push_back(NewArgs[ArgIdx++].getArgument());
5221  }
5222 
5223  // If we have any leftover arguments, then there were too many arguments.
5224  // Complain and fail.
5225  if (ArgIdx < NumArgs) {
5226  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5227  << /*too many args*/1
5228  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5229  << Template
5230  << SourceRange(NewArgs[ArgIdx].getLocation(), NewArgs.getRAngleLoc());
5231  Diag(Template->getLocation(), diag::note_template_decl_here)
5232  << Params->getSourceRange();
5233  return true;
5234  }
5235 
5236  // No problems found with the new argument list, propagate changes back
5237  // to caller.
5238  if (UpdateArgsWithConversions)
5239  TemplateArgs = std::move(NewArgs);
5240 
5241  return false;
5242 }
5243 
5244 namespace {
5245  class UnnamedLocalNoLinkageFinder
5246  : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
5247  {
5248  Sema &S;
5249  SourceRange SR;
5250 
5252 
5253  public:
5254  UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
5255 
5256  bool Visit(QualType T) {
5257  return T.isNull() ? false : inherited::Visit(T.getTypePtr());
5258  }
5259 
5260 #define TYPE(Class, Parent) \
5261  bool Visit##Class##Type(const Class##Type *);
5262 #define ABSTRACT_TYPE(Class, Parent) \
5263  bool Visit##Class##Type(const Class##Type *) { return false; }
5264 #define NON_CANONICAL_TYPE(Class, Parent) \
5265  bool Visit##Class##Type(const Class##Type *) { return false; }
5266 #include "clang/AST/TypeNodes.def"
5267 
5268  bool VisitTagDecl(const TagDecl *Tag);
5269  bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
5270  };
5271 } // end anonymous namespace
5272 
5273 bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
5274  return false;
5275 }
5276 
5277 bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
5278  return Visit(T->getElementType());
5279 }
5280 
5281 bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
5282  return Visit(T->getPointeeType());
5283 }
5284 
5285 bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
5286  const BlockPointerType* T) {
5287  return Visit(T->getPointeeType());
5288 }
5289 
5290 bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
5291  const LValueReferenceType* T) {
5292  return Visit(T->getPointeeType());
5293 }
5294 
5295 bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
5296  const RValueReferenceType* T) {
5297  return Visit(T->getPointeeType());
5298 }
5299 
5300 bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
5301  const MemberPointerType* T) {
5302  return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
5303 }
5304 
5305 bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
5306  const ConstantArrayType* T) {
5307  return Visit(T->getElementType());
5308 }
5309 
5310 bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
5311  const IncompleteArrayType* T) {
5312  return Visit(T->getElementType());
5313 }
5314 
5315 bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
5316  const VariableArrayType* T) {
5317  return Visit(T->getElementType());
5318 }
5319 
5320 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
5321  const DependentSizedArrayType* T) {
5322  return Visit(T->getElementType());
5323 }
5324 
5325 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
5326  const DependentSizedExtVectorType* T) {
5327  return Visit(T->getElementType());
5328 }
5329 
5330 bool UnnamedLocalNoLinkageFinder::VisitDependentAddressSpaceType(
5331  const DependentAddressSpaceType *T) {
5332  return Visit(T->getPointeeType());
5333 }
5334 
5335 bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
5336  return Visit(T->getElementType());
5337 }
5338 
5339 bool UnnamedLocalNoLinkageFinder::VisitDependentVectorType(
5340  const DependentVectorType *T) {
5341  return Visit(T->getElementType());
5342 }
5343 
5344 bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
5345  return Visit(T->getElementType());
5346 }
5347 
5348 bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
5349  const FunctionProtoType* T) {
5350  for (const auto &A : T->param_types()) {
5351  if (Visit(A))
5352  return true;
5353  }
5354 
5355  return Visit(T->getReturnType());
5356 }
5357 
5358 bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
5359  const FunctionNoProtoType* T) {
5360  return Visit(T->getReturnType());
5361 }
5362 
5363 bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
5364  const UnresolvedUsingType*) {
5365  return false;
5366 }
5367 
5368 bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
5369  return false;
5370 }
5371 
5372 bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
5373  return Visit(T->getUnderlyingType());
5374 }
5375 
5376 bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
5377  return false;
5378 }
5379 
5380 bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
5381  const UnaryTransformType*) {
5382  return false;
5383 }
5384 
5385 bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
5386  return Visit(T->getDeducedType());
5387 }
5388 
5389 bool UnnamedLocalNoLinkageFinder::VisitDeducedTemplateSpecializationType(
5391  return Visit(T->getDeducedType());
5392 }
5393 
5394 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
5395  return VisitTagDecl(T->getDecl());
5396 }
5397 
5398 bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
5399  return VisitTagDecl(T->getDecl());
5400 }
5401 
5402 bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
5403  const TemplateTypeParmType*) {
5404  return false;
5405 }
5406 
5407 bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
5409  return false;
5410 }
5411 
5412 bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
5413  const TemplateSpecializationType*) {
5414  return false;
5415 }
5416 
5417 bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
5418  const InjectedClassNameType* T) {
5419  return VisitTagDecl(T->getDecl());
5420 }
5421 
5422 bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
5423  const DependentNameType* T) {
5424  return VisitNestedNameSpecifier(T->getQualifier());
5425 }
5426 
5427 bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
5429  return VisitNestedNameSpecifier(T->getQualifier());
5430 }
5431 
5432 bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
5433  const PackExpansionType* T) {
5434  return Visit(T->getPattern());
5435 }
5436 
5437 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
5438  return false;
5439 }
5440 
5441 bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
5442  const ObjCInterfaceType *) {
5443  return false;
5444 }
5445 
5446 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
5447  const ObjCObjectPointerType *) {
5448  return false;
5449 }
5450 
5451 bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
5452  return Visit(T->getValueType());
5453 }
5454 
5455 bool UnnamedLocalNoLinkageFinder::VisitPipeType(const PipeType* T) {
5456  return false;
5457 }
5458 
5459 bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
5460  if (Tag->getDeclContext()->isFunctionOrMethod()) {
5461  S.Diag(SR.getBegin(),
5462  S.getLangOpts().CPlusPlus11 ?
5463  diag::warn_cxx98_compat_template_arg_local_type :
5464  diag::ext_template_arg_local_type)
5465  << S.Context.getTypeDeclType(Tag) << SR;
5466  return true;
5467  }
5468 
5469  if (!Tag->hasNameForLinkage()) {
5470  S.Diag(SR.getBegin(),
5471  S.getLangOpts().CPlusPlus11 ?
5472  diag::warn_cxx98_compat_template_arg_unnamed_type :
5473  diag::ext_template_arg_unnamed_type) << SR;
5474  S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
5475  return true;
5476  }
5477 
5478  return false;
5479 }
5480 
5481 bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
5482  NestedNameSpecifier *NNS) {
5483  if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
5484  return true;
5485 
5486  switch (NNS->getKind()) {
5492  return false;
5493 
5496  return Visit(QualType(NNS->getAsType(), 0));
5497  }
5498  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
5499 }
5500 
5501 /// Check a template argument against its corresponding
5502 /// template type parameter.
5503 ///
5504 /// This routine implements the semantics of C++ [temp.arg.type]. It
5505 /// returns true if an error occurred, and false otherwise.
5507  TypeSourceInfo *ArgInfo) {
5508  assert(ArgInfo && "invalid TypeSourceInfo");
5509  QualType Arg = ArgInfo->getType();
5510  SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
5511 
5512  if (Arg->isVariablyModifiedType()) {
5513  return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
5514  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
5515  return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
5516  }
5517 
5518  // C++03 [temp.arg.type]p2:
5519  // A local type, a type with no linkage, an unnamed type or a type
5520  // compounded from any of these types shall not be used as a
5521  // template-argument for a template type-parameter.
5522  //
5523  // C++11 allows these, and even in C++03 we allow them as an extension with
5524  // a warning.
5525  if (LangOpts.CPlusPlus11 || Arg->hasUnnamedOrLocalType()) {
5526  UnnamedLocalNoLinkageFinder Finder(*this, SR);
5527  (void)Finder.Visit(Context.getCanonicalType(Arg));
5528  }
5529 
5530  return false;
5531 }
5532 
5537 };
5538 
5539 /// Determine whether the given template argument is a null pointer
5540 /// value of the appropriate type.
5541 static NullPointerValueKind
5543  QualType ParamType, Expr *Arg,
5544  Decl *Entity = nullptr) {
5545  if (Arg->isValueDependent() || Arg->isTypeDependent())
5546  return NPV_NotNullPointer;
5547 
5548  // dllimport'd entities aren't constant but are available inside of template
5549  // arguments.
5550  if (Entity && Entity->hasAttr<DLLImportAttr>())
5551  return NPV_NotNullPointer;
5552 
5553  if (!S.isCompleteType(Arg->getExprLoc(), ParamType))
5554  llvm_unreachable(
5555  "Incomplete parameter type in isNullPointerValueTemplateArgument!");
5556 
5557  if (!S.getLangOpts().CPlusPlus11)
5558  return NPV_NotNullPointer;
5559 
5560  // Determine whether we have a constant expression.
5562  if (ArgRV.isInvalid())
5563  return NPV_Error;
5564  Arg = ArgRV.get();
5565 
5566  Expr::EvalResult EvalResult;
5568  EvalResult.Diag = &Notes;
5569  if (!Arg->EvaluateAsRValue(EvalResult, S.Context) ||
5570  EvalResult.HasSideEffects) {
5571  SourceLocation DiagLoc = Arg->getExprLoc();
5572 
5573  // If our only note is the usual "invalid subexpression" note, just point
5574  // the caret at its location rather than producing an essentially
5575  // redundant note.
5576  if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
5577  diag::note_invalid_subexpr_in_const_expr) {
5578  DiagLoc = Notes[0].first;
5579  Notes.clear();
5580  }
5581 
5582  S.Diag(DiagLoc, diag::err_template_arg_not_address_constant)
5583  << Arg->getType() << Arg->getSourceRange();
5584  for (unsigned I = 0, N = Notes.size(); I != N; ++I)
5585  S.Diag(Notes[I].first, Notes[I].second);
5586 
5587  S.Diag(Param->getLocation(), diag::note_template_param_here);
5588  return NPV_Error;
5589  }
5590 
5591  // C++11 [temp.arg.nontype]p1:
5592  // - an address constant expression of type std::nullptr_t
5593  if (Arg->getType()->isNullPtrType())
5594  return NPV_NullPointer;
5595 
5596  // - a constant expression that evaluates to a null pointer value (4.10); or
5597  // - a constant expression that evaluates to a null member pointer value
5598  // (4.11); or
5599  if ((EvalResult.Val.isLValue() && !EvalResult.Val.getLValueBase()) ||
5600  (EvalResult.Val.isMemberPointer() &&
5601  !EvalResult.Val.getMemberPointerDecl())) {
5602  // If our expression has an appropriate type, we've succeeded.
5603  bool ObjCLifetimeConversion;
5604  if (S.Context.hasSameUnqualifiedType(Arg->getType(), ParamType) ||
5605  S.IsQualificationConversion(Arg->getType(), ParamType, false,
5606  ObjCLifetimeConversion))
5607  return NPV_NullPointer;
5608 
5609  // The types didn't match, but we know we got a null pointer; complain,
5610  // then recover as if the types were correct.
5611  S.Diag(Arg->getExprLoc(), diag::err_template_arg_wrongtype_null_constant)
5612  << Arg->getType() << ParamType << Arg->getSourceRange();
5613  S.Diag(Param->getLocation(), diag::note_template_param_here);
5614  return NPV_NullPointer;
5615  }
5616 
5617  // If we don't have a null pointer value, but we do have a NULL pointer
5618  // constant, suggest a cast to the appropriate type.
5620  std::string Code = "static_cast<" + ParamType.getAsString() + ">(";
5621  S.Diag(Arg->getExprLoc(), diag::err_template_arg_untyped_null_constant)
5622  << ParamType << FixItHint::CreateInsertion(Arg->getLocStart(), Code)
5624  ")");
5625  S.Diag(Param->getLocation(), diag::note_template_param_here);
5626  return NPV_NullPointer;
5627  }
5628 
5629  // FIXME: If we ever want to support general, address-constant expressions
5630  // as non-type template arguments, we should return the ExprResult here to
5631  // be interpreted by the caller.
5632  return NPV_NotNullPointer;
5633 }
5634 
5635 /// Checks whether the given template argument is compatible with its
5636 /// template parameter.
5638  Sema &S, NonTypeTemplateParmDecl *Param, QualType ParamType, Expr *ArgIn,
5639  Expr *Arg, QualType ArgType) {
5640  bool ObjCLifetimeConversion;
5641  if (ParamType->isPointerType() &&
5642  !ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType() &&
5643  S.IsQualificationConversion(ArgType, ParamType, false,
5644  ObjCLifetimeConversion)) {
5645  // For pointer-to-object types, qualification conversions are
5646  // permitted.
5647  } else {
5648  if (const ReferenceType *ParamRef = ParamType->getAs<ReferenceType>()) {
5649  if (!ParamRef->getPointeeType()->isFunctionType()) {
5650  // C++ [temp.arg.nontype]p5b3:
5651  // For a non-type template-parameter of type reference to
5652  // object, no conversions apply. The type referred to by the
5653  // reference may be more cv-qualified than the (otherwise
5654  // identical) type of the template- argument. The
5655  // template-parameter is bound directly to the
5656  // template-argument, which shall be an lvalue.
5657 
5658  // FIXME: Other qualifiers?
5659  unsigned ParamQuals = ParamRef->getPointeeType().getCVRQualifiers();
5660  unsigned ArgQuals = ArgType.getCVRQualifiers();
5661 
5662  if ((ParamQuals | ArgQuals) != ParamQuals) {
5663  S.Diag(Arg->getLocStart(),
5664  diag::err_template_arg_ref_bind_ignores_quals)
5665  << ParamType << Arg->getType() << Arg->getSourceRange();
5666  S.Diag(Param->getLocation(), diag::note_template_param_here);
5667  return true;
5668  }
5669  }
5670  }
5671 
5672  // At this point, the template argument refers to an object or
5673  // function with external linkage. We now need to check whether the
5674  // argument and parameter types are compatible.
5675  if (!S.Context.hasSameUnqualifiedType(ArgType,
5676  ParamType.getNonReferenceType())) {
5677  // We can't perform this conversion or binding.
5678  if (ParamType->isReferenceType())
5679  S.Diag(Arg->getLocStart(), diag::err_template_arg_no_ref_bind)
5680  << ParamType << ArgIn->getType() << Arg->getSourceRange();
5681  else
5682  S.Diag(Arg->getLocStart(), diag::err_template_arg_not_convertible)
5683  << ArgIn->getType() << ParamType << Arg->getSourceRange();
5684  S.Diag(Param->getLocation(), diag::note_template_param_here);
5685  return true;
5686  }
5687  }
5688 
5689  return false;
5690 }
5691 
5692 /// Checks whether the given template argument is the address
5693 /// of an object or function according to C++ [temp.arg.nontype]p1.
5694 static bool
5696  NonTypeTemplateParmDecl *Param,
5697  QualType ParamType,
5698  Expr *ArgIn,
5699  TemplateArgument &Converted) {
5700  bool Invalid = false;
5701  Expr *Arg = ArgIn;
5702  QualType ArgType = Arg->getType();
5703 
5704  bool AddressTaken = false;
5705  SourceLocation AddrOpLoc;
5706  if (S.getLangOpts().MicrosoftExt) {
5707  // Microsoft Visual C++ strips all casts, allows an arbitrary number of
5708  // dereference and address-of operators.
5709  Arg = Arg->IgnoreParenCasts();
5710 
5711  bool ExtWarnMSTemplateArg = false;
5712  UnaryOperatorKind FirstOpKind;
5713  SourceLocation FirstOpLoc;
5714  while (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
5715  UnaryOperatorKind UnOpKind = UnOp->getOpcode();
5716  if (UnOpKind == UO_Deref)
5717  ExtWarnMSTemplateArg = true;
5718  if (UnOpKind == UO_AddrOf || UnOpKind == UO_Deref) {
5719  Arg = UnOp->getSubExpr()->IgnoreParenCasts();
5720  if (!AddrOpLoc.isValid()) {
5721  FirstOpKind = UnOpKind;
5722  FirstOpLoc = UnOp->getOperatorLoc();
5723  }
5724  } else
5725  break;
5726  }
5727  if (FirstOpLoc.isValid()) {
5728  if (ExtWarnMSTemplateArg)
5729  S.Diag(ArgIn->getLocStart(), diag::ext_ms_deref_template_argument)
5730  << ArgIn->getSourceRange();
5731 
5732  if (FirstOpKind == UO_AddrOf)
5733  AddressTaken = true;
5734  else if (Arg->getType()->isPointerType()) {
5735  // We cannot let pointers get dereferenced here, that is obviously not a
5736  // constant expression.
5737  assert(FirstOpKind == UO_Deref);
5738  S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
5739  << Arg->getSourceRange();
5740  }
5741  }
5742  } else {
5743  // See through any implicit casts we added to fix the type.
5744  Arg = Arg->IgnoreImpCasts();
5745 
5746  // C++ [temp.arg.nontype]p1:
5747  //
5748  // A template-argument for a non-type, non-template
5749  // template-parameter shall be one of: [...]
5750  //
5751  // -- the address of an object or function with external
5752  // linkage, including function templates and function
5753  // template-ids but excluding non-static class members,
5754  // expressed as & id-expression where the & is optional if
5755  // the name refers to a function or array, or if the
5756  // corresponding template-parameter is a reference; or
5757 
5758  // In C++98/03 mode, give an extension warning on any extra parentheses.
5759  // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
5760  bool ExtraParens = false;
5761  while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
5762  if (!Invalid && !ExtraParens) {
5763  S.Diag(Arg->getLocStart(),
5764  S.getLangOpts().CPlusPlus11