clang  13.0.0git
SemaTemplate.cpp
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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //===----------------------------------------------------------------------===//
7 //
8 // This file implements semantic analysis for C++ templates.
9 //===----------------------------------------------------------------------===//
10 
11 #include "TreeTransform.h"
12 #include "clang/AST/ASTConsumer.h"
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/DeclFriend.h"
15 #include "clang/AST/DeclTemplate.h"
16 #include "clang/AST/Expr.h"
17 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/TypeVisitor.h"
20 #include "clang/Basic/Builtins.h"
23 #include "clang/Basic/Stack.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
27 #include "clang/Sema/Lookup.h"
28 #include "clang/Sema/Overload.h"
30 #include "clang/Sema/Scope.h"
32 #include "clang/Sema/Template.h"
34 #include "llvm/ADT/SmallBitVector.h"
35 #include "llvm/ADT/SmallString.h"
36 #include "llvm/ADT/StringExtras.h"
37 
38 #include <iterator>
39 using namespace clang;
40 using namespace sema;
41 
42 // Exported for use by Parser.
45  unsigned N) {
46  if (!N) return SourceRange();
47  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
48 }
49 
50 unsigned Sema::getTemplateDepth(Scope *S) const {
51  unsigned Depth = 0;
52 
53  // Each template parameter scope represents one level of template parameter
54  // depth.
55  for (Scope *TempParamScope = S->getTemplateParamParent(); TempParamScope;
56  TempParamScope = TempParamScope->getParent()->getTemplateParamParent()) {
57  ++Depth;
58  }
59 
60  // Note that there are template parameters with the given depth.
61  auto ParamsAtDepth = [&](unsigned D) { Depth = std::max(Depth, D + 1); };
62 
63  // Look for parameters of an enclosing generic lambda. We don't create a
64  // template parameter scope for these.
65  for (FunctionScopeInfo *FSI : getFunctionScopes()) {
66  if (auto *LSI = dyn_cast<LambdaScopeInfo>(FSI)) {
67  if (!LSI->TemplateParams.empty()) {
68  ParamsAtDepth(LSI->AutoTemplateParameterDepth);
69  break;
70  }
71  if (LSI->GLTemplateParameterList) {
72  ParamsAtDepth(LSI->GLTemplateParameterList->getDepth());
73  break;
74  }
75  }
76  }
77 
78  // Look for parameters of an enclosing terse function template. We don't
79  // create a template parameter scope for these either.
80  for (const InventedTemplateParameterInfo &Info :
81  getInventedParameterInfos()) {
82  if (!Info.TemplateParams.empty()) {
83  ParamsAtDepth(Info.AutoTemplateParameterDepth);
84  break;
85  }
86  }
87 
88  return Depth;
89 }
90 
91 /// \brief Determine whether the declaration found is acceptable as the name
92 /// of a template and, if so, return that template declaration. Otherwise,
93 /// returns null.
94 ///
95 /// Note that this may return an UnresolvedUsingValueDecl if AllowDependent
96 /// is true. In all other cases it will return a TemplateDecl (or null).
98  bool AllowFunctionTemplates,
99  bool AllowDependent) {
100  D = D->getUnderlyingDecl();
101 
102  if (isa<TemplateDecl>(D)) {
103  if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
104  return nullptr;
105 
106  return D;
107  }
108 
109  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
110  // C++ [temp.local]p1:
111  // Like normal (non-template) classes, class templates have an
112  // injected-class-name (Clause 9). The injected-class-name
113  // can be used with or without a template-argument-list. When
114  // it is used without a template-argument-list, it is
115  // equivalent to the injected-class-name followed by the
116  // template-parameters of the class template enclosed in
117  // <>. When it is used with a template-argument-list, it
118  // refers to the specified class template specialization,
119  // which could be the current specialization or another
120  // specialization.
121  if (Record->isInjectedClassName()) {
122  Record = cast<CXXRecordDecl>(Record->getDeclContext());
123  if (Record->getDescribedClassTemplate())
124  return Record->getDescribedClassTemplate();
125 
127  = dyn_cast<ClassTemplateSpecializationDecl>(Record))
128  return Spec->getSpecializedTemplate();
129  }
130 
131  return nullptr;
132  }
133 
134  // 'using Dependent::foo;' can resolve to a template name.
135  // 'using typename Dependent::foo;' cannot (not even if 'foo' is an
136  // injected-class-name).
137  if (AllowDependent && isa<UnresolvedUsingValueDecl>(D))
138  return D;
139 
140  return nullptr;
141 }
142 
144  bool AllowFunctionTemplates,
145  bool AllowDependent) {
146  LookupResult::Filter filter = R.makeFilter();
147  while (filter.hasNext()) {
148  NamedDecl *Orig = filter.next();
149  if (!getAsTemplateNameDecl(Orig, AllowFunctionTemplates, AllowDependent))
150  filter.erase();
151  }
152  filter.done();
153 }
154 
156  bool AllowFunctionTemplates,
157  bool AllowDependent,
158  bool AllowNonTemplateFunctions) {
159  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
160  if (getAsTemplateNameDecl(*I, AllowFunctionTemplates, AllowDependent))
161  return true;
162  if (AllowNonTemplateFunctions &&
163  isa<FunctionDecl>((*I)->getUnderlyingDecl()))
164  return true;
165  }
166 
167  return false;
168 }
169 
171  CXXScopeSpec &SS,
172  bool hasTemplateKeyword,
173  const UnqualifiedId &Name,
174  ParsedType ObjectTypePtr,
175  bool EnteringContext,
176  TemplateTy &TemplateResult,
177  bool &MemberOfUnknownSpecialization,
178  bool Disambiguation) {
179  assert(getLangOpts().CPlusPlus && "No template names in C!");
180 
181  DeclarationName TName;
182  MemberOfUnknownSpecialization = false;
183 
184  switch (Name.getKind()) {
186  TName = DeclarationName(Name.Identifier);
187  break;
188 
190  TName = Context.DeclarationNames.getCXXOperatorName(
191  Name.OperatorFunctionId.Operator);
192  break;
193 
195  TName = Context.DeclarationNames.getCXXLiteralOperatorName(Name.Identifier);
196  break;
197 
198  default:
199  return TNK_Non_template;
200  }
201 
202  QualType ObjectType = ObjectTypePtr.get();
203 
204  AssumedTemplateKind AssumedTemplate;
205  LookupResult R(*this, TName, Name.getBeginLoc(), LookupOrdinaryName);
206  if (LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
207  MemberOfUnknownSpecialization, SourceLocation(),
208  &AssumedTemplate,
209  /*AllowTypoCorrection=*/!Disambiguation))
210  return TNK_Non_template;
211 
212  if (AssumedTemplate != AssumedTemplateKind::None) {
213  TemplateResult = TemplateTy::make(Context.getAssumedTemplateName(TName));
214  // Let the parser know whether we found nothing or found functions; if we
215  // found nothing, we want to more carefully check whether this is actually
216  // a function template name versus some other kind of undeclared identifier.
217  return AssumedTemplate == AssumedTemplateKind::FoundNothing
220  }
221 
222  if (R.empty())
223  return TNK_Non_template;
224 
225  NamedDecl *D = nullptr;
226  if (R.isAmbiguous()) {
227  // If we got an ambiguity involving a non-function template, treat this
228  // as a template name, and pick an arbitrary template for error recovery.
229  bool AnyFunctionTemplates = false;
230  for (NamedDecl *FoundD : R) {
231  if (NamedDecl *FoundTemplate = getAsTemplateNameDecl(FoundD)) {
232  if (isa<FunctionTemplateDecl>(FoundTemplate))
233  AnyFunctionTemplates = true;
234  else {
235  D = FoundTemplate;
236  break;
237  }
238  }
239  }
240 
241  // If we didn't find any templates at all, this isn't a template name.
242  // Leave the ambiguity for a later lookup to diagnose.
243  if (!D && !AnyFunctionTemplates) {
244  R.suppressDiagnostics();
245  return TNK_Non_template;
246  }
247 
248  // If the only templates were function templates, filter out the rest.
249  // We'll diagnose the ambiguity later.
250  if (!D)
251  FilterAcceptableTemplateNames(R);
252  }
253 
254  // At this point, we have either picked a single template name declaration D
255  // or we have a non-empty set of results R containing either one template name
256  // declaration or a set of function templates.
257 
258  TemplateName Template;
259  TemplateNameKind TemplateKind;
260 
261  unsigned ResultCount = R.end() - R.begin();
262  if (!D && ResultCount > 1) {
263  // We assume that we'll preserve the qualifier from a function
264  // template name in other ways.
265  Template = Context.getOverloadedTemplateName(R.begin(), R.end());
266  TemplateKind = TNK_Function_template;
267 
268  // We'll do this lookup again later.
270  } else {
271  if (!D) {
272  D = getAsTemplateNameDecl(*R.begin());
273  assert(D && "unambiguous result is not a template name");
274  }
275 
276  if (isa<UnresolvedUsingValueDecl>(D)) {
277  // We don't yet know whether this is a template-name or not.
278  MemberOfUnknownSpecialization = true;
279  return TNK_Non_template;
280  }
281 
282  TemplateDecl *TD = cast<TemplateDecl>(D);
283 
284  if (SS.isSet() && !SS.isInvalid()) {
285  NestedNameSpecifier *Qualifier = SS.getScopeRep();
286  Template = Context.getQualifiedTemplateName(Qualifier,
287  hasTemplateKeyword, TD);
288  } else {
289  Template = TemplateName(TD);
290  }
291 
292  if (isa<FunctionTemplateDecl>(TD)) {
293  TemplateKind = TNK_Function_template;
294 
295  // We'll do this lookup again later.
297  } else {
298  assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
299  isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
300  isa<BuiltinTemplateDecl>(TD) || isa<ConceptDecl>(TD));
301  TemplateKind =
302  isa<VarTemplateDecl>(TD) ? TNK_Var_template :
303  isa<ConceptDecl>(TD) ? TNK_Concept_template :
305  }
306  }
307 
308  TemplateResult = TemplateTy::make(Template);
309  return TemplateKind;
310 }
311 
313  SourceLocation NameLoc,
314  ParsedTemplateTy *Template) {
315  CXXScopeSpec SS;
316  bool MemberOfUnknownSpecialization = false;
317 
318  // We could use redeclaration lookup here, but we don't need to: the
319  // syntactic form of a deduction guide is enough to identify it even
320  // if we can't look up the template name at all.
321  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
322  if (LookupTemplateName(R, S, SS, /*ObjectType*/ QualType(),
323  /*EnteringContext*/ false,
324  MemberOfUnknownSpecialization))
325  return false;
326 
327  if (R.empty()) return false;
328  if (R.isAmbiguous()) {
329  // FIXME: Diagnose an ambiguity if we find at least one template.
331  return false;
332  }
333 
334  // We only treat template-names that name type templates as valid deduction
335  // guide names.
337  if (!TD || !getAsTypeTemplateDecl(TD))
338  return false;
339 
340  if (Template)
341  *Template = TemplateTy::make(TemplateName(TD));
342  return true;
343 }
344 
346  SourceLocation IILoc,
347  Scope *S,
348  const CXXScopeSpec *SS,
349  TemplateTy &SuggestedTemplate,
350  TemplateNameKind &SuggestedKind) {
351  // We can't recover unless there's a dependent scope specifier preceding the
352  // template name.
353  // FIXME: Typo correction?
354  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
355  computeDeclContext(*SS))
356  return false;
357 
358  // The code is missing a 'template' keyword prior to the dependent template
359  // name.
361  Diag(IILoc, diag::err_template_kw_missing)
362  << Qualifier << II.getName()
363  << FixItHint::CreateInsertion(IILoc, "template ");
364  SuggestedTemplate
365  = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
366  SuggestedKind = TNK_Dependent_template_name;
367  return true;
368 }
369 
371  Scope *S, CXXScopeSpec &SS,
372  QualType ObjectType,
373  bool EnteringContext,
374  bool &MemberOfUnknownSpecialization,
375  RequiredTemplateKind RequiredTemplate,
376  AssumedTemplateKind *ATK,
377  bool AllowTypoCorrection) {
378  if (ATK)
380 
381  if (SS.isInvalid())
382  return true;
383 
384  Found.setTemplateNameLookup(true);
385 
386  // Determine where to perform name lookup
387  MemberOfUnknownSpecialization = false;
388  DeclContext *LookupCtx = nullptr;
389  bool IsDependent = false;
390  if (!ObjectType.isNull()) {
391  // This nested-name-specifier occurs in a member access expression, e.g.,
392  // x->B::f, and we are looking into the type of the object.
393  assert(SS.isEmpty() && "ObjectType and scope specifier cannot coexist");
394  LookupCtx = computeDeclContext(ObjectType);
395  IsDependent = !LookupCtx && ObjectType->isDependentType();
396  assert((IsDependent || !ObjectType->isIncompleteType() ||
397  ObjectType->castAs<TagType>()->isBeingDefined()) &&
398  "Caller should have completed object type");
399 
400  // Template names cannot appear inside an Objective-C class or object type
401  // or a vector type.
402  //
403  // FIXME: This is wrong. For example:
404  //
405  // template<typename T> using Vec = T __attribute__((ext_vector_type(4)));
406  // Vec<int> vi;
407  // vi.Vec<int>::~Vec<int>();
408  //
409  // ... should be accepted but we will not treat 'Vec' as a template name
410  // here. The right thing to do would be to check if the name is a valid
411  // vector component name, and look up a template name if not. And similarly
412  // for lookups into Objective-C class and object types, where the same
413  // problem can arise.
414  if (ObjectType->isObjCObjectOrInterfaceType() ||
415  ObjectType->isVectorType()) {
416  Found.clear();
417  return false;
418  }
419  } else if (SS.isNotEmpty()) {
420  // This nested-name-specifier occurs after another nested-name-specifier,
421  // so long into the context associated with the prior nested-name-specifier.
422  LookupCtx = computeDeclContext(SS, EnteringContext);
423  IsDependent = !LookupCtx && isDependentScopeSpecifier(SS);
424 
425  // The declaration context must be complete.
426  if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
427  return true;
428  }
429 
430  bool ObjectTypeSearchedInScope = false;
431  bool AllowFunctionTemplatesInLookup = true;
432  if (LookupCtx) {
433  // Perform "qualified" name lookup into the declaration context we
434  // computed, which is either the type of the base of a member access
435  // expression or the declaration context associated with a prior
436  // nested-name-specifier.
437  LookupQualifiedName(Found, LookupCtx);
438 
439  // FIXME: The C++ standard does not clearly specify what happens in the
440  // case where the object type is dependent, and implementations vary. In
441  // Clang, we treat a name after a . or -> as a template-name if lookup
442  // finds a non-dependent member or member of the current instantiation that
443  // is a type template, or finds no such members and lookup in the context
444  // of the postfix-expression finds a type template. In the latter case, the
445  // name is nonetheless dependent, and we may resolve it to a member of an
446  // unknown specialization when we come to instantiate the template.
447  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
448  }
449 
450  if (SS.isEmpty() && (ObjectType.isNull() || Found.empty())) {
451  // C++ [basic.lookup.classref]p1:
452  // In a class member access expression (5.2.5), if the . or -> token is
453  // immediately followed by an identifier followed by a <, the
454  // identifier must be looked up to determine whether the < is the
455  // beginning of a template argument list (14.2) or a less-than operator.
456  // The identifier is first looked up in the class of the object
457  // expression. If the identifier is not found, it is then looked up in
458  // the context of the entire postfix-expression and shall name a class
459  // template.
460  if (S)
461  LookupName(Found, S);
462 
463  if (!ObjectType.isNull()) {
464  // FIXME: We should filter out all non-type templates here, particularly
465  // variable templates and concepts. But the exclusion of alias templates
466  // and template template parameters is a wording defect.
467  AllowFunctionTemplatesInLookup = false;
468  ObjectTypeSearchedInScope = true;
469  }
470 
471  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
472  }
473 
474  if (Found.isAmbiguous())
475  return false;
476 
477  if (ATK && SS.isEmpty() && ObjectType.isNull() &&
478  !RequiredTemplate.hasTemplateKeyword()) {
479  // C++2a [temp.names]p2:
480  // A name is also considered to refer to a template if it is an
481  // unqualified-id followed by a < and name lookup finds either one or more
482  // functions or finds nothing.
483  //
484  // To keep our behavior consistent, we apply the "finds nothing" part in
485  // all language modes, and diagnose the empty lookup in ActOnCallExpr if we
486  // successfully form a call to an undeclared template-id.
487  bool AllFunctions =
488  getLangOpts().CPlusPlus20 &&
489  std::all_of(Found.begin(), Found.end(), [](NamedDecl *ND) {
490  return isa<FunctionDecl>(ND->getUnderlyingDecl());
491  });
492  if (AllFunctions || (Found.empty() && !IsDependent)) {
493  // If lookup found any functions, or if this is a name that can only be
494  // used for a function, then strongly assume this is a function
495  // template-id.
496  *ATK = (Found.empty() && Found.getLookupName().isIdentifier())
497  ? AssumedTemplateKind::FoundNothing
498  : AssumedTemplateKind::FoundFunctions;
499  Found.clear();
500  return false;
501  }
502  }
503 
504  if (Found.empty() && !IsDependent && AllowTypoCorrection) {
505  // If we did not find any names, and this is not a disambiguation, attempt
506  // to correct any typos.
507  DeclarationName Name = Found.getLookupName();
508  Found.clear();
509  // Simple filter callback that, for keywords, only accepts the C++ *_cast
510  DefaultFilterCCC FilterCCC{};
511  FilterCCC.WantTypeSpecifiers = false;
512  FilterCCC.WantExpressionKeywords = false;
513  FilterCCC.WantRemainingKeywords = false;
514  FilterCCC.WantCXXNamedCasts = true;
515  if (TypoCorrection Corrected =
516  CorrectTypo(Found.getLookupNameInfo(), Found.getLookupKind(), S,
517  &SS, FilterCCC, CTK_ErrorRecovery, LookupCtx)) {
518  if (auto *ND = Corrected.getFoundDecl())
519  Found.addDecl(ND);
520  FilterAcceptableTemplateNames(Found);
521  if (Found.isAmbiguous()) {
522  Found.clear();
523  } else if (!Found.empty()) {
524  Found.setLookupName(Corrected.getCorrection());
525  if (LookupCtx) {
526  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
527  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
528  Name.getAsString() == CorrectedStr;
529  diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
530  << Name << LookupCtx << DroppedSpecifier
531  << SS.getRange());
532  } else {
533  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
534  }
535  }
536  }
537  }
538 
539  NamedDecl *ExampleLookupResult =
540  Found.empty() ? nullptr : Found.getRepresentativeDecl();
541  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
542  if (Found.empty()) {
543  if (IsDependent) {
544  MemberOfUnknownSpecialization = true;
545  return false;
546  }
547 
548  // If a 'template' keyword was used, a lookup that finds only non-template
549  // names is an error.
550  if (ExampleLookupResult && RequiredTemplate) {
551  Diag(Found.getNameLoc(), diag::err_template_kw_refers_to_non_template)
552  << Found.getLookupName() << SS.getRange()
553  << RequiredTemplate.hasTemplateKeyword()
554  << RequiredTemplate.getTemplateKeywordLoc();
555  Diag(ExampleLookupResult->getUnderlyingDecl()->getLocation(),
556  diag::note_template_kw_refers_to_non_template)
557  << Found.getLookupName();
558  return true;
559  }
560 
561  return false;
562  }
563 
564  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
565  !getLangOpts().CPlusPlus11) {
566  // C++03 [basic.lookup.classref]p1:
567  // [...] If the lookup in the class of the object expression finds a
568  // template, the name is also looked up in the context of the entire
569  // postfix-expression and [...]
570  //
571  // Note: C++11 does not perform this second lookup.
572  LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
573  LookupOrdinaryName);
574  FoundOuter.setTemplateNameLookup(true);
575  LookupName(FoundOuter, S);
576  // FIXME: We silently accept an ambiguous lookup here, in violation of
577  // [basic.lookup]/1.
578  FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
579 
580  NamedDecl *OuterTemplate;
581  if (FoundOuter.empty()) {
582  // - if the name is not found, the name found in the class of the
583  // object expression is used, otherwise
584  } else if (FoundOuter.isAmbiguous() || !FoundOuter.isSingleResult() ||
585  !(OuterTemplate =
586  getAsTemplateNameDecl(FoundOuter.getFoundDecl()))) {
587  // - if the name is found in the context of the entire
588  // postfix-expression and does not name a class template, the name
589  // found in the class of the object expression is used, otherwise
590  FoundOuter.clear();
591  } else if (!Found.isSuppressingDiagnostics()) {
592  // - if the name found is a class template, it must refer to the same
593  // entity as the one found in the class of the object expression,
594  // otherwise the program is ill-formed.
595  if (!Found.isSingleResult() ||
596  getAsTemplateNameDecl(Found.getFoundDecl())->getCanonicalDecl() !=
597  OuterTemplate->getCanonicalDecl()) {
598  Diag(Found.getNameLoc(),
599  diag::ext_nested_name_member_ref_lookup_ambiguous)
600  << Found.getLookupName()
601  << ObjectType;
603  diag::note_ambig_member_ref_object_type)
604  << ObjectType;
605  Diag(FoundOuter.getFoundDecl()->getLocation(),
606  diag::note_ambig_member_ref_scope);
607 
608  // Recover by taking the template that we found in the object
609  // expression's type.
610  }
611  }
612  }
613 
614  return false;
615 }
616 
618  SourceLocation Less,
619  SourceLocation Greater) {
620  if (TemplateName.isInvalid())
621  return;
622 
623  DeclarationNameInfo NameInfo;
624  CXXScopeSpec SS;
625  LookupNameKind LookupKind;
626 
627  DeclContext *LookupCtx = nullptr;
628  NamedDecl *Found = nullptr;
629  bool MissingTemplateKeyword = false;
630 
631  // Figure out what name we looked up.
632  if (auto *DRE = dyn_cast<DeclRefExpr>(TemplateName.get())) {
633  NameInfo = DRE->getNameInfo();
634  SS.Adopt(DRE->getQualifierLoc());
635  LookupKind = LookupOrdinaryName;
636  Found = DRE->getFoundDecl();
637  } else if (auto *ME = dyn_cast<MemberExpr>(TemplateName.get())) {
638  NameInfo = ME->getMemberNameInfo();
639  SS.Adopt(ME->getQualifierLoc());
640  LookupKind = LookupMemberName;
641  LookupCtx = ME->getBase()->getType()->getAsCXXRecordDecl();
642  Found = ME->getMemberDecl();
643  } else if (auto *DSDRE =
644  dyn_cast<DependentScopeDeclRefExpr>(TemplateName.get())) {
645  NameInfo = DSDRE->getNameInfo();
646  SS.Adopt(DSDRE->getQualifierLoc());
647  MissingTemplateKeyword = true;
648  } else if (auto *DSME =
649  dyn_cast<CXXDependentScopeMemberExpr>(TemplateName.get())) {
650  NameInfo = DSME->getMemberNameInfo();
651  SS.Adopt(DSME->getQualifierLoc());
652  MissingTemplateKeyword = true;
653  } else {
654  llvm_unreachable("unexpected kind of potential template name");
655  }
656 
657  // If this is a dependent-scope lookup, diagnose that the 'template' keyword
658  // was missing.
659  if (MissingTemplateKeyword) {
660  Diag(NameInfo.getBeginLoc(), diag::err_template_kw_missing)
661  << "" << NameInfo.getName().getAsString() << SourceRange(Less, Greater);
662  return;
663  }
664 
665  // Try to correct the name by looking for templates and C++ named casts.
666  struct TemplateCandidateFilter : CorrectionCandidateCallback {
667  Sema &S;
668  TemplateCandidateFilter(Sema &S) : S(S) {
669  WantTypeSpecifiers = false;
670  WantExpressionKeywords = false;
671  WantRemainingKeywords = false;
672  WantCXXNamedCasts = true;
673  };
674  bool ValidateCandidate(const TypoCorrection &Candidate) override {
675  if (auto *ND = Candidate.getCorrectionDecl())
676  return S.getAsTemplateNameDecl(ND);
677  return Candidate.isKeyword();
678  }
679 
680  std::unique_ptr<CorrectionCandidateCallback> clone() override {
681  return std::make_unique<TemplateCandidateFilter>(*this);
682  }
683  };
684 
685  DeclarationName Name = NameInfo.getName();
686  TemplateCandidateFilter CCC(*this);
687  if (TypoCorrection Corrected = CorrectTypo(NameInfo, LookupKind, S, &SS, CCC,
688  CTK_ErrorRecovery, LookupCtx)) {
689  auto *ND = Corrected.getFoundDecl();
690  if (ND)
691  ND = getAsTemplateNameDecl(ND);
692  if (ND || Corrected.isKeyword()) {
693  if (LookupCtx) {
694  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
695  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
696  Name.getAsString() == CorrectedStr;
697  diagnoseTypo(Corrected,
698  PDiag(diag::err_non_template_in_member_template_id_suggest)
699  << Name << LookupCtx << DroppedSpecifier
700  << SS.getRange(), false);
701  } else {
702  diagnoseTypo(Corrected,
703  PDiag(diag::err_non_template_in_template_id_suggest)
704  << Name, false);
705  }
706  if (Found)
707  Diag(Found->getLocation(),
708  diag::note_non_template_in_template_id_found);
709  return;
710  }
711  }
712 
713  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
714  << Name << SourceRange(Less, Greater);
715  if (Found)
716  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
717 }
718 
719 /// ActOnDependentIdExpression - Handle a dependent id-expression that
720 /// was just parsed. This is only possible with an explicit scope
721 /// specifier naming a dependent type.
724  SourceLocation TemplateKWLoc,
725  const DeclarationNameInfo &NameInfo,
726  bool isAddressOfOperand,
727  const TemplateArgumentListInfo *TemplateArgs) {
728  DeclContext *DC = getFunctionLevelDeclContext();
729 
730  // C++11 [expr.prim.general]p12:
731  // An id-expression that denotes a non-static data member or non-static
732  // member function of a class can only be used:
733  // (...)
734  // - if that id-expression denotes a non-static data member and it
735  // appears in an unevaluated operand.
736  //
737  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
738  // CXXDependentScopeMemberExpr. The former can instantiate to either
739  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
740  // always a MemberExpr.
741  bool MightBeCxx11UnevalField =
742  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
743 
744  // Check if the nested name specifier is an enum type.
745  bool IsEnum = false;
746  if (NestedNameSpecifier *NNS = SS.getScopeRep())
747  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
748 
749  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
750  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
751  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType();
752 
753  // Since the 'this' expression is synthesized, we don't need to
754  // perform the double-lookup check.
755  NamedDecl *FirstQualifierInScope = nullptr;
756 
758  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
759  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
760  FirstQualifierInScope, NameInfo, TemplateArgs);
761  }
762 
763  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
764 }
765 
768  SourceLocation TemplateKWLoc,
769  const DeclarationNameInfo &NameInfo,
770  const TemplateArgumentListInfo *TemplateArgs) {
771  // DependentScopeDeclRefExpr::Create requires a valid QualifierLoc
772  NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
773  if (!QualifierLoc)
774  return ExprError();
775 
777  Context, QualifierLoc, TemplateKWLoc, NameInfo, TemplateArgs);
778 }
779 
780 
781 /// Determine whether we would be unable to instantiate this template (because
782 /// it either has no definition, or is in the process of being instantiated).
784  NamedDecl *Instantiation,
785  bool InstantiatedFromMember,
786  const NamedDecl *Pattern,
787  const NamedDecl *PatternDef,
789  bool Complain /*= true*/) {
790  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
791  isa<VarDecl>(Instantiation));
792 
793  bool IsEntityBeingDefined = false;
794  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
795  IsEntityBeingDefined = TD->isBeingDefined();
796 
797  if (PatternDef && !IsEntityBeingDefined) {
798  NamedDecl *SuggestedDef = nullptr;
799  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
800  /*OnlyNeedComplete*/false)) {
801  // If we're allowed to diagnose this and recover, do so.
802  bool Recover = Complain && !isSFINAEContext();
803  if (Complain)
804  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
806  return !Recover;
807  }
808  return false;
809  }
810 
811  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
812  return true;
813 
815  QualType InstantiationTy;
816  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
817  InstantiationTy = Context.getTypeDeclType(TD);
818  if (PatternDef) {
819  Diag(PointOfInstantiation,
820  diag::err_template_instantiate_within_definition)
821  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
822  << InstantiationTy;
823  // Not much point in noting the template declaration here, since
824  // we're lexically inside it.
825  Instantiation->setInvalidDecl();
826  } else if (InstantiatedFromMember) {
827  if (isa<FunctionDecl>(Instantiation)) {
828  Diag(PointOfInstantiation,
829  diag::err_explicit_instantiation_undefined_member)
830  << /*member function*/ 1 << Instantiation->getDeclName()
831  << Instantiation->getDeclContext();
832  Note = diag::note_explicit_instantiation_here;
833  } else {
834  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
835  Diag(PointOfInstantiation,
836  diag::err_implicit_instantiate_member_undefined)
837  << InstantiationTy;
838  Note = diag::note_member_declared_at;
839  }
840  } else {
841  if (isa<FunctionDecl>(Instantiation)) {
842  Diag(PointOfInstantiation,
843  diag::err_explicit_instantiation_undefined_func_template)
844  << Pattern;
845  Note = diag::note_explicit_instantiation_here;
846  } else if (isa<TagDecl>(Instantiation)) {
847  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
848  << (TSK != TSK_ImplicitInstantiation)
849  << InstantiationTy;
850  Note = diag::note_template_decl_here;
851  } else {
852  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
853  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
854  Diag(PointOfInstantiation,
855  diag::err_explicit_instantiation_undefined_var_template)
856  << Instantiation;
857  Instantiation->setInvalidDecl();
858  } else
859  Diag(PointOfInstantiation,
860  diag::err_explicit_instantiation_undefined_member)
861  << /*static data member*/ 2 << Instantiation->getDeclName()
862  << Instantiation->getDeclContext();
863  Note = diag::note_explicit_instantiation_here;
864  }
865  }
866  if (Note) // Diagnostics were emitted.
867  Diag(Pattern->getLocation(), Note.getValue());
868 
869  // In general, Instantiation isn't marked invalid to get more than one
870  // error for multiple undefined instantiations. But the code that does
871  // explicit declaration -> explicit definition conversion can't handle
872  // invalid declarations, so mark as invalid in that case.
874  Instantiation->setInvalidDecl();
875  return true;
876 }
877 
878 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
879 /// that the template parameter 'PrevDecl' is being shadowed by a new
880 /// declaration at location Loc. Returns true to indicate that this is
881 /// an error, and false otherwise.
883  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
884 
885  // C++ [temp.local]p4:
886  // A template-parameter shall not be redeclared within its
887  // scope (including nested scopes).
888  //
889  // Make this a warning when MSVC compatibility is requested.
890  unsigned DiagId = getLangOpts().MSVCCompat ? diag::ext_template_param_shadow
891  : diag::err_template_param_shadow;
892  Diag(Loc, DiagId) << cast<NamedDecl>(PrevDecl)->getDeclName();
893  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
894 }
895 
896 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
897 /// the parameter D to reference the templated declaration and return a pointer
898 /// to the template declaration. Otherwise, do nothing to D and return null.
900  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
901  D = Temp->getTemplatedDecl();
902  return Temp;
903  }
904  return nullptr;
905 }
906 
908  SourceLocation EllipsisLoc) const {
909  assert(Kind == Template &&
910  "Only template template arguments can be pack expansions here");
911  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
912  "Template template argument pack expansion without packs");
913  ParsedTemplateArgument Result(*this);
914  Result.EllipsisLoc = EllipsisLoc;
915  return Result;
916 }
917 
919  const ParsedTemplateArgument &Arg) {
920 
921  switch (Arg.getKind()) {
923  TypeSourceInfo *DI;
924  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
925  if (!DI)
926  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
927  return TemplateArgumentLoc(TemplateArgument(T), DI);
928  }
929 
931  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
933  }
934 
936  TemplateName Template = Arg.getAsTemplate().get();
937  TemplateArgument TArg;
938  if (Arg.getEllipsisLoc().isValid())
939  TArg = TemplateArgument(Template, Optional<unsigned int>());
940  else
941  TArg = Template;
942  return TemplateArgumentLoc(
943  SemaRef.Context, TArg,
945  Arg.getLocation(), Arg.getEllipsisLoc());
946  }
947  }
948 
949  llvm_unreachable("Unhandled parsed template argument");
950 }
951 
952 /// Translates template arguments as provided by the parser
953 /// into template arguments used by semantic analysis.
955  TemplateArgumentListInfo &TemplateArgs) {
956  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
957  TemplateArgs.addArgument(translateTemplateArgument(*this,
958  TemplateArgsIn[I]));
959 }
960 
962  SourceLocation Loc,
963  IdentifierInfo *Name) {
964  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
966  if (PrevDecl && PrevDecl->isTemplateParameter())
967  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
968 }
969 
970 /// Convert a parsed type into a parsed template argument. This is mostly
971 /// trivial, except that we may have parsed a C++17 deduced class template
972 /// specialization type, in which case we should form a template template
973 /// argument instead of a type template argument.
975  TypeSourceInfo *TInfo;
976  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
977  if (T.isNull())
978  return ParsedTemplateArgument();
979  assert(TInfo && "template argument with no location");
980 
981  // If we might have formed a deduced template specialization type, convert
982  // it to a template template argument.
983  if (getLangOpts().CPlusPlus17) {
984  TypeLoc TL = TInfo->getTypeLoc();
985  SourceLocation EllipsisLoc;
986  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
987  EllipsisLoc = PET.getEllipsisLoc();
988  TL = PET.getPatternLoc();
989  }
990 
991  CXXScopeSpec SS;
992  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
993  SS.Adopt(ET.getQualifierLoc());
994  TL = ET.getNamedTypeLoc();
995  }
996 
997  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
998  TemplateName Name = DTST.getTypePtr()->getTemplateName();
999  if (SS.isSet())
1000  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
1001  /*HasTemplateKeyword*/ false,
1002  Name.getAsTemplateDecl());
1003  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
1004  DTST.getTemplateNameLoc());
1005  if (EllipsisLoc.isValid())
1006  Result = Result.getTemplatePackExpansion(EllipsisLoc);
1007  return Result;
1008  }
1009  }
1010 
1011  // This is a normal type template argument. Note, if the type template
1012  // argument is an injected-class-name for a template, it has a dual nature
1013  // and can be used as either a type or a template. We handle that in
1014  // convertTypeTemplateArgumentToTemplate.
1017  TInfo->getTypeLoc().getBeginLoc());
1018 }
1019 
1020 /// ActOnTypeParameter - Called when a C++ template type parameter
1021 /// (e.g., "typename T") has been parsed. Typename specifies whether
1022 /// the keyword "typename" was used to declare the type parameter
1023 /// (otherwise, "class" was used), and KeyLoc is the location of the
1024 /// "class" or "typename" keyword. ParamName is the name of the
1025 /// parameter (NULL indicates an unnamed template parameter) and
1026 /// ParamNameLoc is the location of the parameter name (if any).
1027 /// If the type parameter has a default argument, it will be added
1028 /// later via ActOnTypeParameterDefault.
1030  SourceLocation EllipsisLoc,
1031  SourceLocation KeyLoc,
1032  IdentifierInfo *ParamName,
1033  SourceLocation ParamNameLoc,
1034  unsigned Depth, unsigned Position,
1035  SourceLocation EqualLoc,
1036  ParsedType DefaultArg,
1037  bool HasTypeConstraint) {
1038  assert(S->isTemplateParamScope() &&
1039  "Template type parameter not in template parameter scope!");
1040 
1041  bool IsParameterPack = EllipsisLoc.isValid();
1042  TemplateTypeParmDecl *Param
1044  KeyLoc, ParamNameLoc, Depth, Position,
1045  ParamName, Typename, IsParameterPack,
1046  HasTypeConstraint);
1047  Param->setAccess(AS_public);
1048 
1049  if (Param->isParameterPack())
1050  if (auto *LSI = getEnclosingLambda())
1051  LSI->LocalPacks.push_back(Param);
1052 
1053  if (ParamName) {
1054  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
1055 
1056  // Add the template parameter into the current scope.
1057  S->AddDecl(Param);
1058  IdResolver.AddDecl(Param);
1059  }
1060 
1061  // C++0x [temp.param]p9:
1062  // A default template-argument may be specified for any kind of
1063  // template-parameter that is not a template parameter pack.
1064  if (DefaultArg && IsParameterPack) {
1065  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1066  DefaultArg = nullptr;
1067  }
1068 
1069  // Handle the default argument, if provided.
1070  if (DefaultArg) {
1071  TypeSourceInfo *DefaultTInfo;
1072  GetTypeFromParser(DefaultArg, &DefaultTInfo);
1073 
1074  assert(DefaultTInfo && "expected source information for type");
1075 
1076  // Check for unexpanded parameter packs.
1077  if (DiagnoseUnexpandedParameterPack(ParamNameLoc, DefaultTInfo,
1078  UPPC_DefaultArgument))
1079  return Param;
1080 
1081  // Check the template argument itself.
1082  if (CheckTemplateArgument(Param, DefaultTInfo)) {
1083  Param->setInvalidDecl();
1084  return Param;
1085  }
1086 
1087  Param->setDefaultArgument(DefaultTInfo);
1088  }
1089 
1090  return Param;
1091 }
1092 
1093 /// Convert the parser's template argument list representation into our form.
1096  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
1097  TemplateId.RAngleLoc);
1098  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
1099  TemplateId.NumArgs);
1100  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
1101  return TemplateArgs;
1102 }
1103 
1105  TemplateIdAnnotation *TypeConstr,
1106  TemplateTypeParmDecl *ConstrainedParameter,
1107  SourceLocation EllipsisLoc) {
1108  return BuildTypeConstraint(SS, TypeConstr, ConstrainedParameter, EllipsisLoc,
1109  false);
1110 }
1111 
1113  TemplateIdAnnotation *TypeConstr,
1114  TemplateTypeParmDecl *ConstrainedParameter,
1115  SourceLocation EllipsisLoc,
1116  bool AllowUnexpandedPack) {
1117  TemplateName TN = TypeConstr->Template.get();
1118  ConceptDecl *CD = cast<ConceptDecl>(TN.getAsTemplateDecl());
1119 
1120  // C++2a [temp.param]p4:
1121  // [...] The concept designated by a type-constraint shall be a type
1122  // concept ([temp.concept]).
1123  if (!CD->isTypeConcept()) {
1124  Diag(TypeConstr->TemplateNameLoc,
1125  diag::err_type_constraint_non_type_concept);
1126  return true;
1127  }
1128 
1129  bool WereArgsSpecified = TypeConstr->LAngleLoc.isValid();
1130 
1131  if (!WereArgsSpecified &&
1133  Diag(TypeConstr->TemplateNameLoc,
1134  diag::err_type_constraint_missing_arguments) << CD;
1135  return true;
1136  }
1137 
1138  DeclarationNameInfo ConceptName(DeclarationName(TypeConstr->Name),
1139  TypeConstr->TemplateNameLoc);
1140 
1141  TemplateArgumentListInfo TemplateArgs;
1142  if (TypeConstr->LAngleLoc.isValid()) {
1143  TemplateArgs =
1144  makeTemplateArgumentListInfo(*this, *TypeConstr);
1145 
1146  if (EllipsisLoc.isInvalid() && !AllowUnexpandedPack) {
1147  for (TemplateArgumentLoc Arg : TemplateArgs.arguments()) {
1148  if (DiagnoseUnexpandedParameterPack(Arg, UPPC_TypeConstraint))
1149  return true;
1150  }
1151  }
1152  }
1153  return AttachTypeConstraint(
1154  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc(),
1155  ConceptName, CD,
1156  TypeConstr->LAngleLoc.isValid() ? &TemplateArgs : nullptr,
1157  ConstrainedParameter, EllipsisLoc);
1158 }
1159 
1160 template<typename ArgumentLocAppender>
1163  ConceptDecl *NamedConcept, SourceLocation LAngleLoc,
1164  SourceLocation RAngleLoc, QualType ConstrainedType,
1165  SourceLocation ParamNameLoc, ArgumentLocAppender Appender,
1166  SourceLocation EllipsisLoc) {
1167 
1168  TemplateArgumentListInfo ConstraintArgs;
1169  ConstraintArgs.addArgument(
1171  /*NTTPType=*/QualType(), ParamNameLoc));
1172 
1173  ConstraintArgs.setRAngleLoc(RAngleLoc);
1174  ConstraintArgs.setLAngleLoc(LAngleLoc);
1175  Appender(ConstraintArgs);
1176 
1177  // C++2a [temp.param]p4:
1178  // [...] This constraint-expression E is called the immediately-declared
1179  // constraint of T. [...]
1180  CXXScopeSpec SS;
1181  SS.Adopt(NS);
1182  ExprResult ImmediatelyDeclaredConstraint = S.CheckConceptTemplateId(
1183  SS, /*TemplateKWLoc=*/SourceLocation(), NameInfo,
1184  /*FoundDecl=*/NamedConcept, NamedConcept, &ConstraintArgs);
1185  if (ImmediatelyDeclaredConstraint.isInvalid() || !EllipsisLoc.isValid())
1186  return ImmediatelyDeclaredConstraint;
1187 
1188  // C++2a [temp.param]p4:
1189  // [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
1190  //
1191  // We have the following case:
1192  //
1193  // template<typename T> concept C1 = true;
1194  // template<C1... T> struct s1;
1195  //
1196  // The constraint: (C1<T> && ...)
1197  //
1198  // Note that the type of C1<T> is known to be 'bool', so we don't need to do
1199  // any unqualified lookups for 'operator&&' here.
1200  return S.BuildCXXFoldExpr(/*UnqualifiedLookup=*/nullptr,
1201  /*LParenLoc=*/SourceLocation(),
1202  ImmediatelyDeclaredConstraint.get(), BO_LAnd,
1203  EllipsisLoc, /*RHS=*/nullptr,
1204  /*RParenLoc=*/SourceLocation(),
1205  /*NumExpansions=*/None);
1206 }
1207 
1208 /// Attach a type-constraint to a template parameter.
1209 /// \returns true if an error occured. This can happen if the
1210 /// immediately-declared constraint could not be formed (e.g. incorrect number
1211 /// of arguments for the named concept).
1213  DeclarationNameInfo NameInfo,
1214  ConceptDecl *NamedConcept,
1215  const TemplateArgumentListInfo *TemplateArgs,
1216  TemplateTypeParmDecl *ConstrainedParameter,
1217  SourceLocation EllipsisLoc) {
1218  // C++2a [temp.param]p4:
1219  // [...] If Q is of the form C<A1, ..., An>, then let E' be
1220  // C<T, A1, ..., An>. Otherwise, let E' be C<T>. [...]
1221  const ASTTemplateArgumentListInfo *ArgsAsWritten =
1222  TemplateArgs ? ASTTemplateArgumentListInfo::Create(Context,
1223  *TemplateArgs) : nullptr;
1224 
1225  QualType ParamAsArgument(ConstrainedParameter->getTypeForDecl(), 0);
1226 
1227  ExprResult ImmediatelyDeclaredConstraint =
1229  *this, NS, NameInfo, NamedConcept,
1230  TemplateArgs ? TemplateArgs->getLAngleLoc() : SourceLocation(),
1231  TemplateArgs ? TemplateArgs->getRAngleLoc() : SourceLocation(),
1232  ParamAsArgument, ConstrainedParameter->getLocation(),
1233  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1234  if (TemplateArgs)
1235  for (const auto &ArgLoc : TemplateArgs->arguments())
1236  ConstraintArgs.addArgument(ArgLoc);
1237  }, EllipsisLoc);
1238  if (ImmediatelyDeclaredConstraint.isInvalid())
1239  return true;
1240 
1241  ConstrainedParameter->setTypeConstraint(NS, NameInfo,
1242  /*FoundDecl=*/NamedConcept,
1243  NamedConcept, ArgsAsWritten,
1244  ImmediatelyDeclaredConstraint.get());
1245  return false;
1246 }
1247 
1249  SourceLocation EllipsisLoc) {
1250  if (NTTP->getType() != TL.getType() ||
1253  diag::err_unsupported_placeholder_constraint)
1255  return true;
1256  }
1257  // FIXME: Concepts: This should be the type of the placeholder, but this is
1258  // unclear in the wording right now.
1259  DeclRefExpr *Ref =
1260  BuildDeclRefExpr(NTTP, NTTP->getType(), VK_PRValue, NTTP->getLocation());
1261  if (!Ref)
1262  return true;
1263  ExprResult ImmediatelyDeclaredConstraint =
1266  TL.getNamedConcept(), TL.getLAngleLoc(), TL.getRAngleLoc(),
1267  BuildDecltypeType(Ref, NTTP->getLocation()), NTTP->getLocation(),
1268  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1269  for (unsigned I = 0, C = TL.getNumArgs(); I != C; ++I)
1270  ConstraintArgs.addArgument(TL.getArgLoc(I));
1271  }, EllipsisLoc);
1272  if (ImmediatelyDeclaredConstraint.isInvalid() ||
1273  !ImmediatelyDeclaredConstraint.isUsable())
1274  return true;
1275 
1276  NTTP->setPlaceholderTypeConstraint(ImmediatelyDeclaredConstraint.get());
1277  return false;
1278 }
1279 
1280 /// Check that the type of a non-type template parameter is
1281 /// well-formed.
1282 ///
1283 /// \returns the (possibly-promoted) parameter type if valid;
1284 /// otherwise, produces a diagnostic and returns a NULL type.
1286  SourceLocation Loc) {
1287  if (TSI->getType()->isUndeducedType()) {
1288  // C++17 [temp.dep.expr]p3:
1289  // An id-expression is type-dependent if it contains
1290  // - an identifier associated by name lookup with a non-type
1291  // template-parameter declared with a type that contains a
1292  // placeholder type (7.1.7.4),
1293  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
1294  }
1295 
1296  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
1297 }
1298 
1299 /// Require the given type to be a structural type, and diagnose if it is not.
1300 ///
1301 /// \return \c true if an error was produced.
1303  if (T->isDependentType())
1304  return false;
1305 
1306  if (RequireCompleteType(Loc, T, diag::err_template_nontype_parm_incomplete))
1307  return true;
1308 
1309  if (T->isStructuralType())
1310  return false;
1311 
1312  // Structural types are required to be object types or lvalue references.
1313  if (T->isRValueReferenceType()) {
1314  Diag(Loc, diag::err_template_nontype_parm_rvalue_ref) << T;
1315  return true;
1316  }
1317 
1318  // Don't mention structural types in our diagnostic prior to C++20. Also,
1319  // there's not much more we can say about non-scalar non-class types --
1320  // because we can't see functions or arrays here, those can only be language
1321  // extensions.
1322  if (!getLangOpts().CPlusPlus20 ||
1323  (!T->isScalarType() && !T->isRecordType())) {
1324  Diag(Loc, diag::err_template_nontype_parm_bad_type) << T;
1325  return true;
1326  }
1327 
1328  // Structural types are required to be literal types.
1329  if (RequireLiteralType(Loc, T, diag::err_template_nontype_parm_not_literal))
1330  return true;
1331 
1332  Diag(Loc, diag::err_template_nontype_parm_not_structural) << T;
1333 
1334  // Drill down into the reason why the class is non-structural.
1335  while (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
1336  // All members are required to be public and non-mutable, and can't be of
1337  // rvalue reference type. Check these conditions first to prefer a "local"
1338  // reason over a more distant one.
1339  for (const FieldDecl *FD : RD->fields()) {
1340  if (FD->getAccess() != AS_public) {
1341  Diag(FD->getLocation(), diag::note_not_structural_non_public) << T << 0;
1342  return true;
1343  }
1344  if (FD->isMutable()) {
1345  Diag(FD->getLocation(), diag::note_not_structural_mutable_field) << T;
1346  return true;
1347  }
1348  if (FD->getType()->isRValueReferenceType()) {
1349  Diag(FD->getLocation(), diag::note_not_structural_rvalue_ref_field)
1350  << T;
1351  return true;
1352  }
1353  }
1354 
1355  // All bases are required to be public.
1356  for (const auto &BaseSpec : RD->bases()) {
1357  if (BaseSpec.getAccessSpecifier() != AS_public) {
1358  Diag(BaseSpec.getBaseTypeLoc(), diag::note_not_structural_non_public)
1359  << T << 1;
1360  return true;
1361  }
1362  }
1363 
1364  // All subobjects are required to be of structural types.
1365  SourceLocation SubLoc;
1366  QualType SubType;
1367  int Kind = -1;
1368 
1369  for (const FieldDecl *FD : RD->fields()) {
1370  QualType T = Context.getBaseElementType(FD->getType());
1371  if (!T->isStructuralType()) {
1372  SubLoc = FD->getLocation();
1373  SubType = T;
1374  Kind = 0;
1375  break;
1376  }
1377  }
1378 
1379  if (Kind == -1) {
1380  for (const auto &BaseSpec : RD->bases()) {
1381  QualType T = BaseSpec.getType();
1382  if (!T->isStructuralType()) {
1383  SubLoc = BaseSpec.getBaseTypeLoc();
1384  SubType = T;
1385  Kind = 1;
1386  break;
1387  }
1388  }
1389  }
1390 
1391  assert(Kind != -1 && "couldn't find reason why type is not structural");
1392  Diag(SubLoc, diag::note_not_structural_subobject)
1393  << T << Kind << SubType;
1394  T = SubType;
1395  RD = T->getAsCXXRecordDecl();
1396  }
1397 
1398  return true;
1399 }
1400 
1402  SourceLocation Loc) {
1403  // We don't allow variably-modified types as the type of non-type template
1404  // parameters.
1405  if (T->isVariablyModifiedType()) {
1406  Diag(Loc, diag::err_variably_modified_nontype_template_param)
1407  << T;
1408  return QualType();
1409  }
1410 
1411  // C++ [temp.param]p4:
1412  //
1413  // A non-type template-parameter shall have one of the following
1414  // (optionally cv-qualified) types:
1415  //
1416  // -- integral or enumeration type,
1417  if (T->isIntegralOrEnumerationType() ||
1418  // -- pointer to object or pointer to function,
1419  T->isPointerType() ||
1420  // -- lvalue reference to object or lvalue reference to function,
1421  T->isLValueReferenceType() ||
1422  // -- pointer to member,
1423  T->isMemberPointerType() ||
1424  // -- std::nullptr_t, or
1425  T->isNullPtrType() ||
1426  // -- a type that contains a placeholder type.
1427  T->isUndeducedType()) {
1428  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1429  // are ignored when determining its type.
1430  return T.getUnqualifiedType();
1431  }
1432 
1433  // C++ [temp.param]p8:
1434  //
1435  // A non-type template-parameter of type "array of T" or
1436  // "function returning T" is adjusted to be of type "pointer to
1437  // T" or "pointer to function returning T", respectively.
1438  if (T->isArrayType() || T->isFunctionType())
1439  return Context.getDecayedType(T);
1440 
1441  // If T is a dependent type, we can't do the check now, so we
1442  // assume that it is well-formed. Note that stripping off the
1443  // qualifiers here is not really correct if T turns out to be
1444  // an array type, but we'll recompute the type everywhere it's
1445  // used during instantiation, so that should be OK. (Using the
1446  // qualified type is equally wrong.)
1447  if (T->isDependentType())
1448  return T.getUnqualifiedType();
1449 
1450  // C++20 [temp.param]p6:
1451  // -- a structural type
1452  if (RequireStructuralType(T, Loc))
1453  return QualType();
1454 
1455  if (!getLangOpts().CPlusPlus20) {
1456  // FIXME: Consider allowing structural types as an extension in C++17. (In
1457  // earlier language modes, the template argument evaluation rules are too
1458  // inflexible.)
1459  Diag(Loc, diag::err_template_nontype_parm_bad_structural_type) << T;
1460  return QualType();
1461  }
1462 
1463  Diag(Loc, diag::warn_cxx17_compat_template_nontype_parm_type) << T;
1464  return T.getUnqualifiedType();
1465 }
1466 
1468  unsigned Depth,
1469  unsigned Position,
1470  SourceLocation EqualLoc,
1471  Expr *Default) {
1472  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1473 
1474  // Check that we have valid decl-specifiers specified.
1475  auto CheckValidDeclSpecifiers = [this, &D] {
1476  // C++ [temp.param]
1477  // p1
1478  // template-parameter:
1479  // ...
1480  // parameter-declaration
1481  // p2
1482  // ... A storage class shall not be specified in a template-parameter
1483  // declaration.
1484  // [dcl.typedef]p1:
1485  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1486  // of a parameter-declaration
1487  const DeclSpec &DS = D.getDeclSpec();
1488  auto EmitDiag = [this](SourceLocation Loc) {
1489  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1490  << FixItHint::CreateRemoval(Loc);
1491  };
1493  EmitDiag(DS.getStorageClassSpecLoc());
1494 
1496  EmitDiag(DS.getThreadStorageClassSpecLoc());
1497 
1498  // [dcl.inline]p1:
1499  // The inline specifier can be applied only to the declaration or
1500  // definition of a variable or function.
1501 
1502  if (DS.isInlineSpecified())
1503  EmitDiag(DS.getInlineSpecLoc());
1504 
1505  // [dcl.constexpr]p1:
1506  // The constexpr specifier shall be applied only to the definition of a
1507  // variable or variable template or the declaration of a function or
1508  // function template.
1509 
1510  if (DS.hasConstexprSpecifier())
1511  EmitDiag(DS.getConstexprSpecLoc());
1512 
1513  // [dcl.fct.spec]p1:
1514  // Function-specifiers can be used only in function declarations.
1515 
1516  if (DS.isVirtualSpecified())
1517  EmitDiag(DS.getVirtualSpecLoc());
1518 
1519  if (DS.hasExplicitSpecifier())
1520  EmitDiag(DS.getExplicitSpecLoc());
1521 
1522  if (DS.isNoreturnSpecified())
1523  EmitDiag(DS.getNoreturnSpecLoc());
1524  };
1525 
1526  CheckValidDeclSpecifiers();
1527 
1528  if (TInfo->getType()->isUndeducedType()) {
1529  Diag(D.getIdentifierLoc(),
1530  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1531  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1532  }
1533 
1534  assert(S->isTemplateParamScope() &&
1535  "Non-type template parameter not in template parameter scope!");
1536  bool Invalid = false;
1537 
1538  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1539  if (T.isNull()) {
1540  T = Context.IntTy; // Recover with an 'int' type.
1541  Invalid = true;
1542  }
1543 
1544  CheckFunctionOrTemplateParamDeclarator(S, D);
1545 
1546  IdentifierInfo *ParamName = D.getIdentifier();
1547  bool IsParameterPack = D.hasEllipsis();
1549  Context, Context.getTranslationUnitDecl(), D.getBeginLoc(),
1550  D.getIdentifierLoc(), Depth, Position, ParamName, T, IsParameterPack,
1551  TInfo);
1552  Param->setAccess(AS_public);
1553 
1554  if (AutoTypeLoc TL = TInfo->getTypeLoc().getContainedAutoTypeLoc())
1555  if (TL.isConstrained())
1556  if (AttachTypeConstraint(TL, Param, D.getEllipsisLoc()))
1557  Invalid = true;
1558 
1559  if (Invalid)
1560  Param->setInvalidDecl();
1561 
1562  if (Param->isParameterPack())
1563  if (auto *LSI = getEnclosingLambda())
1564  LSI->LocalPacks.push_back(Param);
1565 
1566  if (ParamName) {
1568  ParamName);
1569 
1570  // Add the template parameter into the current scope.
1571  S->AddDecl(Param);
1572  IdResolver.AddDecl(Param);
1573  }
1574 
1575  // C++0x [temp.param]p9:
1576  // A default template-argument may be specified for any kind of
1577  // template-parameter that is not a template parameter pack.
1578  if (Default && IsParameterPack) {
1579  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1580  Default = nullptr;
1581  }
1582 
1583  // Check the well-formedness of the default template argument, if provided.
1584  if (Default) {
1585  // Check for unexpanded parameter packs.
1586  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1587  return Param;
1588 
1589  TemplateArgument Converted;
1590  ExprResult DefaultRes =
1591  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1592  if (DefaultRes.isInvalid()) {
1593  Param->setInvalidDecl();
1594  return Param;
1595  }
1596  Default = DefaultRes.get();
1597 
1598  Param->setDefaultArgument(Default);
1599  }
1600 
1601  return Param;
1602 }
1603 
1604 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1605 /// parameter (e.g. T in template <template <typename> class T> class array)
1606 /// has been parsed. S is the current scope.
1608  SourceLocation TmpLoc,
1609  TemplateParameterList *Params,
1610  SourceLocation EllipsisLoc,
1611  IdentifierInfo *Name,
1612  SourceLocation NameLoc,
1613  unsigned Depth,
1614  unsigned Position,
1615  SourceLocation EqualLoc,
1616  ParsedTemplateArgument Default) {
1617  assert(S->isTemplateParamScope() &&
1618  "Template template parameter not in template parameter scope!");
1619 
1620  // Construct the parameter object.
1621  bool IsParameterPack = EllipsisLoc.isValid();
1622  TemplateTemplateParmDecl *Param =
1624  NameLoc.isInvalid()? TmpLoc : NameLoc,
1625  Depth, Position, IsParameterPack,
1626  Name, Params);
1627  Param->setAccess(AS_public);
1628 
1629  if (Param->isParameterPack())
1630  if (auto *LSI = getEnclosingLambda())
1631  LSI->LocalPacks.push_back(Param);
1632 
1633  // If the template template parameter has a name, then link the identifier
1634  // into the scope and lookup mechanisms.
1635  if (Name) {
1636  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1637 
1638  S->AddDecl(Param);
1639  IdResolver.AddDecl(Param);
1640  }
1641 
1642  if (Params->size() == 0) {
1643  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1644  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1645  Param->setInvalidDecl();
1646  }
1647 
1648  // C++0x [temp.param]p9:
1649  // A default template-argument may be specified for any kind of
1650  // template-parameter that is not a template parameter pack.
1651  if (IsParameterPack && !Default.isInvalid()) {
1652  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1654  }
1655 
1656  if (!Default.isInvalid()) {
1657  // Check only that we have a template template argument. We don't want to
1658  // try to check well-formedness now, because our template template parameter
1659  // might have dependent types in its template parameters, which we wouldn't
1660  // be able to match now.
1661  //
1662  // If none of the template template parameter's template arguments mention
1663  // other template parameters, we could actually perform more checking here.
1664  // However, it isn't worth doing.
1666  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1667  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1668  << DefaultArg.getSourceRange();
1669  return Param;
1670  }
1671 
1672  // Check for unexpanded parameter packs.
1673  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1674  DefaultArg.getArgument().getAsTemplate(),
1675  UPPC_DefaultArgument))
1676  return Param;
1677 
1678  Param->setDefaultArgument(Context, DefaultArg);
1679  }
1680 
1681  return Param;
1682 }
1683 
1684 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1685 /// constrained by RequiresClause, that contains the template parameters in
1686 /// Params.
1689  SourceLocation ExportLoc,
1690  SourceLocation TemplateLoc,
1691  SourceLocation LAngleLoc,
1692  ArrayRef<NamedDecl *> Params,
1693  SourceLocation RAngleLoc,
1694  Expr *RequiresClause) {
1695  if (ExportLoc.isValid())
1696  Diag(ExportLoc, diag::warn_template_export_unsupported);
1697 
1698  for (NamedDecl *P : Params)
1699  warnOnReservedIdentifier(P);
1700 
1702  Context, TemplateLoc, LAngleLoc,
1703  llvm::makeArrayRef(Params.data(), Params.size()),
1704  RAngleLoc, RequiresClause);
1705 }
1706 
1708  const CXXScopeSpec &SS) {
1709  if (SS.isSet())
1711 }
1712 
1714  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1715  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1716  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1717  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1718  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1719  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1720  assert(TemplateParams && TemplateParams->size() > 0 &&
1721  "No template parameters");
1722  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1723  bool Invalid = false;
1724 
1725  // Check that we can declare a template here.
1726  if (CheckTemplateDeclScope(S, TemplateParams))
1727  return true;
1728 
1730  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1731 
1732  // There is no such thing as an unnamed class template.
1733  if (!Name) {
1734  Diag(KWLoc, diag::err_template_unnamed_class);
1735  return true;
1736  }
1737 
1738  // Find any previous declaration with this name. For a friend with no
1739  // scope explicitly specified, we only look for tag declarations (per
1740  // C++11 [basic.lookup.elab]p2).
1741  DeclContext *SemanticContext;
1742  LookupResult Previous(*this, Name, NameLoc,
1743  (SS.isEmpty() && TUK == TUK_Friend)
1744  ? LookupTagName : LookupOrdinaryName,
1745  forRedeclarationInCurContext());
1746  if (SS.isNotEmpty() && !SS.isInvalid()) {
1747  SemanticContext = computeDeclContext(SS, true);
1748  if (!SemanticContext) {
1749  // FIXME: Horrible, horrible hack! We can't currently represent this
1750  // in the AST, and historically we have just ignored such friend
1751  // class templates, so don't complain here.
1752  Diag(NameLoc, TUK == TUK_Friend
1753  ? diag::warn_template_qualified_friend_ignored
1754  : diag::err_template_qualified_declarator_no_match)
1755  << SS.getScopeRep() << SS.getRange();
1756  return TUK != TUK_Friend;
1757  }
1758 
1759  if (RequireCompleteDeclContext(SS, SemanticContext))
1760  return true;
1761 
1762  // If we're adding a template to a dependent context, we may need to
1763  // rebuilding some of the types used within the template parameter list,
1764  // now that we know what the current instantiation is.
1765  if (SemanticContext->isDependentContext()) {
1766  ContextRAII SavedContext(*this, SemanticContext);
1767  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1768  Invalid = true;
1769  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1770  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1771 
1772  LookupQualifiedName(Previous, SemanticContext);
1773  } else {
1774  SemanticContext = CurContext;
1775 
1776  // C++14 [class.mem]p14:
1777  // If T is the name of a class, then each of the following shall have a
1778  // name different from T:
1779  // -- every member template of class T
1780  if (TUK != TUK_Friend &&
1781  DiagnoseClassNameShadow(SemanticContext,
1782  DeclarationNameInfo(Name, NameLoc)))
1783  return true;
1784 
1785  LookupName(Previous, S);
1786  }
1787 
1788  if (Previous.isAmbiguous())
1789  return true;
1790 
1791  NamedDecl *PrevDecl = nullptr;
1792  if (Previous.begin() != Previous.end())
1793  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1794 
1795  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1796  // Maybe we will complain about the shadowed template parameter.
1797  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1798  // Just pretend that we didn't see the previous declaration.
1799  PrevDecl = nullptr;
1800  }
1801 
1802  // If there is a previous declaration with the same name, check
1803  // whether this is a valid redeclaration.
1804  ClassTemplateDecl *PrevClassTemplate =
1805  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1806 
1807  // We may have found the injected-class-name of a class template,
1808  // class template partial specialization, or class template specialization.
1809  // In these cases, grab the template that is being defined or specialized.
1810  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1811  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1812  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1813  PrevClassTemplate
1814  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1815  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1816  PrevClassTemplate
1817  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1818  ->getSpecializedTemplate();
1819  }
1820  }
1821 
1822  if (TUK == TUK_Friend) {
1823  // C++ [namespace.memdef]p3:
1824  // [...] When looking for a prior declaration of a class or a function
1825  // declared as a friend, and when the name of the friend class or
1826  // function is neither a qualified name nor a template-id, scopes outside
1827  // the innermost enclosing namespace scope are not considered.
1828  if (!SS.isSet()) {
1829  DeclContext *OutermostContext = CurContext;
1830  while (!OutermostContext->isFileContext())
1831  OutermostContext = OutermostContext->getLookupParent();
1832 
1833  if (PrevDecl &&
1834  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1835  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1836  SemanticContext = PrevDecl->getDeclContext();
1837  } else {
1838  // Declarations in outer scopes don't matter. However, the outermost
1839  // context we computed is the semantic context for our new
1840  // declaration.
1841  PrevDecl = PrevClassTemplate = nullptr;
1842  SemanticContext = OutermostContext;
1843 
1844  // Check that the chosen semantic context doesn't already contain a
1845  // declaration of this name as a non-tag type.
1846  Previous.clear(LookupOrdinaryName);
1847  DeclContext *LookupContext = SemanticContext;
1848  while (LookupContext->isTransparentContext())
1849  LookupContext = LookupContext->getLookupParent();
1850  LookupQualifiedName(Previous, LookupContext);
1851 
1852  if (Previous.isAmbiguous())
1853  return true;
1854 
1855  if (Previous.begin() != Previous.end())
1856  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1857  }
1858  }
1859  } else if (PrevDecl &&
1860  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1861  S, SS.isValid()))
1862  PrevDecl = PrevClassTemplate = nullptr;
1863 
1864  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1865  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1866  if (SS.isEmpty() &&
1867  !(PrevClassTemplate &&
1868  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1869  SemanticContext->getRedeclContext()))) {
1870  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1871  Diag(Shadow->getTargetDecl()->getLocation(),
1872  diag::note_using_decl_target);
1873  Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl) << 0;
1874  // Recover by ignoring the old declaration.
1875  PrevDecl = PrevClassTemplate = nullptr;
1876  }
1877  }
1878 
1879  if (PrevClassTemplate) {
1880  // Ensure that the template parameter lists are compatible. Skip this check
1881  // for a friend in a dependent context: the template parameter list itself
1882  // could be dependent.
1883  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1884  !TemplateParameterListsAreEqual(TemplateParams,
1885  PrevClassTemplate->getTemplateParameters(),
1886  /*Complain=*/true,
1887  TPL_TemplateMatch))
1888  return true;
1889 
1890  // C++ [temp.class]p4:
1891  // In a redeclaration, partial specialization, explicit
1892  // specialization or explicit instantiation of a class template,
1893  // the class-key shall agree in kind with the original class
1894  // template declaration (7.1.5.3).
1895  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1896  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1897  TUK == TUK_Definition, KWLoc, Name)) {
1898  Diag(KWLoc, diag::err_use_with_wrong_tag)
1899  << Name
1900  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1901  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1902  Kind = PrevRecordDecl->getTagKind();
1903  }
1904 
1905  // Check for redefinition of this class template.
1906  if (TUK == TUK_Definition) {
1907  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1908  // If we have a prior definition that is not visible, treat this as
1909  // simply making that previous definition visible.
1910  NamedDecl *Hidden = nullptr;
1911  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1912  SkipBody->ShouldSkip = true;
1913  SkipBody->Previous = Def;
1914  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1915  assert(Tmpl && "original definition of a class template is not a "
1916  "class template?");
1917  makeMergedDefinitionVisible(Hidden);
1918  makeMergedDefinitionVisible(Tmpl);
1919  } else {
1920  Diag(NameLoc, diag::err_redefinition) << Name;
1921  Diag(Def->getLocation(), diag::note_previous_definition);
1922  // FIXME: Would it make sense to try to "forget" the previous
1923  // definition, as part of error recovery?
1924  return true;
1925  }
1926  }
1927  }
1928  } else if (PrevDecl) {
1929  // C++ [temp]p5:
1930  // A class template shall not have the same name as any other
1931  // template, class, function, object, enumeration, enumerator,
1932  // namespace, or type in the same scope (3.3), except as specified
1933  // in (14.5.4).
1934  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1935  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1936  return true;
1937  }
1938 
1939  // Check the template parameter list of this declaration, possibly
1940  // merging in the template parameter list from the previous class
1941  // template declaration. Skip this check for a friend in a dependent
1942  // context, because the template parameter list might be dependent.
1943  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1944  CheckTemplateParameterList(
1945  TemplateParams,
1946  PrevClassTemplate
1947  ? PrevClassTemplate->getMostRecentDecl()->getTemplateParameters()
1948  : nullptr,
1949  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1950  SemanticContext->isDependentContext())
1951  ? TPC_ClassTemplateMember
1952  : TUK == TUK_Friend ? TPC_FriendClassTemplate : TPC_ClassTemplate,
1953  SkipBody))
1954  Invalid = true;
1955 
1956  if (SS.isSet()) {
1957  // If the name of the template was qualified, we must be defining the
1958  // template out-of-line.
1959  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1960  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1961  : diag::err_member_decl_does_not_match)
1962  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1963  Invalid = true;
1964  }
1965  }
1966 
1967  // If this is a templated friend in a dependent context we should not put it
1968  // on the redecl chain. In some cases, the templated friend can be the most
1969  // recent declaration tricking the template instantiator to make substitutions
1970  // there.
1971  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1972  bool ShouldAddRedecl
1973  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1974 
1975  CXXRecordDecl *NewClass =
1976  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1977  PrevClassTemplate && ShouldAddRedecl ?
1978  PrevClassTemplate->getTemplatedDecl() : nullptr,
1979  /*DelayTypeCreation=*/true);
1980  SetNestedNameSpecifier(*this, NewClass, SS);
1981  if (NumOuterTemplateParamLists > 0)
1983  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1984  NumOuterTemplateParamLists));
1985 
1986  // Add alignment attributes if necessary; these attributes are checked when
1987  // the ASTContext lays out the structure.
1988  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
1989  AddAlignmentAttributesForRecord(NewClass);
1990  AddMsStructLayoutForRecord(NewClass);
1991  }
1992 
1993  ClassTemplateDecl *NewTemplate
1994  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1995  DeclarationName(Name), TemplateParams,
1996  NewClass);
1997 
1998  if (ShouldAddRedecl)
1999  NewTemplate->setPreviousDecl(PrevClassTemplate);
2000 
2001  NewClass->setDescribedClassTemplate(NewTemplate);
2002 
2003  if (ModulePrivateLoc.isValid())
2004  NewTemplate->setModulePrivate();
2005 
2006  // Build the type for the class template declaration now.
2007  QualType T = NewTemplate->getInjectedClassNameSpecialization();
2008  T = Context.getInjectedClassNameType(NewClass, T);
2009  assert(T->isDependentType() && "Class template type is not dependent?");
2010  (void)T;
2011 
2012  // If we are providing an explicit specialization of a member that is a
2013  // class template, make a note of that.
2014  if (PrevClassTemplate &&
2015  PrevClassTemplate->getInstantiatedFromMemberTemplate())
2016  PrevClassTemplate->setMemberSpecialization();
2017 
2018  // Set the access specifier.
2019  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
2020  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
2021 
2022  // Set the lexical context of these templates
2023  NewClass->setLexicalDeclContext(CurContext);
2024  NewTemplate->setLexicalDeclContext(CurContext);
2025 
2026  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
2027  NewClass->startDefinition();
2028 
2029  ProcessDeclAttributeList(S, NewClass, Attr);
2030 
2031  if (PrevClassTemplate)
2032  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
2033 
2034  AddPushedVisibilityAttribute(NewClass);
2035  inferGslOwnerPointerAttribute(NewClass);
2036 
2037  if (TUK != TUK_Friend) {
2038  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
2039  Scope *Outer = S;
2040  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
2041  Outer = Outer->getParent();
2042  PushOnScopeChains(NewTemplate, Outer);
2043  } else {
2044  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
2045  NewTemplate->setAccess(PrevClassTemplate->getAccess());
2046  NewClass->setAccess(PrevClassTemplate->getAccess());
2047  }
2048 
2049  NewTemplate->setObjectOfFriendDecl();
2050 
2051  // Friend templates are visible in fairly strange ways.
2052  if (!CurContext->isDependentContext()) {
2053  DeclContext *DC = SemanticContext->getRedeclContext();
2054  DC->makeDeclVisibleInContext(NewTemplate);
2055  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
2056  PushOnScopeChains(NewTemplate, EnclosingScope,
2057  /* AddToContext = */ false);
2058  }
2059 
2060  FriendDecl *Friend = FriendDecl::Create(
2061  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
2062  Friend->setAccess(AS_public);
2063  CurContext->addDecl(Friend);
2064  }
2065 
2066  if (PrevClassTemplate)
2067  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
2068 
2069  if (Invalid) {
2070  NewTemplate->setInvalidDecl();
2071  NewClass->setInvalidDecl();
2072  }
2073 
2074  ActOnDocumentableDecl(NewTemplate);
2075 
2076  if (SkipBody && SkipBody->ShouldSkip)
2077  return SkipBody->Previous;
2078 
2079  return NewTemplate;
2080 }
2081 
2082 namespace {
2083 /// Tree transform to "extract" a transformed type from a class template's
2084 /// constructor to a deduction guide.
2085 class ExtractTypeForDeductionGuide
2086  : public TreeTransform<ExtractTypeForDeductionGuide> {
2087  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs;
2088 
2089 public:
2091  ExtractTypeForDeductionGuide(
2092  Sema &SemaRef,
2093  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs)
2094  : Base(SemaRef), MaterializedTypedefs(MaterializedTypedefs) {}
2095 
2096  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
2097 
2098  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
2099  ASTContext &Context = SemaRef.getASTContext();
2100  TypedefNameDecl *OrigDecl = TL.getTypedefNameDecl();
2101  TypedefNameDecl *Decl = OrigDecl;
2102  // Transform the underlying type of the typedef and clone the Decl only if
2103  // the typedef has a dependent context.
2104  if (OrigDecl->getDeclContext()->isDependentContext()) {
2105  TypeLocBuilder InnerTLB;
2106  QualType Transformed =
2107  TransformType(InnerTLB, OrigDecl->getTypeSourceInfo()->getTypeLoc());
2108  TypeSourceInfo *TSI = InnerTLB.getTypeSourceInfo(Context, Transformed);
2109  if (isa<TypeAliasDecl>(OrigDecl))
2111  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2112  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2113  else {
2114  assert(isa<TypedefDecl>(OrigDecl) && "Not a Type alias or typedef");
2116  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2117  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2118  }
2119  MaterializedTypedefs.push_back(Decl);
2120  }
2121 
2122  QualType TDTy = Context.getTypedefType(Decl);
2123  TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(TDTy);
2124  TypedefTL.setNameLoc(TL.getNameLoc());
2125 
2126  return TDTy;
2127  }
2128 };
2129 
2130 /// Transform to convert portions of a constructor declaration into the
2131 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
2132 struct ConvertConstructorToDeductionGuideTransform {
2133  ConvertConstructorToDeductionGuideTransform(Sema &S,
2134  ClassTemplateDecl *Template)
2135  : SemaRef(S), Template(Template) {}
2136 
2137  Sema &SemaRef;
2138  ClassTemplateDecl *Template;
2139 
2140  DeclContext *DC = Template->getDeclContext();
2141  CXXRecordDecl *Primary = Template->getTemplatedDecl();
2142  DeclarationName DeductionGuideName =
2144 
2145  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
2146 
2147  // Index adjustment to apply to convert depth-1 template parameters into
2148  // depth-0 template parameters.
2149  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
2150 
2151  /// Transform a constructor declaration into a deduction guide.
2152  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
2153  CXXConstructorDecl *CD) {
2155 
2156  LocalInstantiationScope Scope(SemaRef);
2157 
2158  // C++ [over.match.class.deduct]p1:
2159  // -- For each constructor of the class template designated by the
2160  // template-name, a function template with the following properties:
2161 
2162  // -- The template parameters are the template parameters of the class
2163  // template followed by the template parameters (including default
2164  // template arguments) of the constructor, if any.
2165  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2166  if (FTD) {
2167  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
2168  SmallVector<NamedDecl *, 16> AllParams;
2169  AllParams.reserve(TemplateParams->size() + InnerParams->size());
2170  AllParams.insert(AllParams.begin(),
2171  TemplateParams->begin(), TemplateParams->end());
2172  SubstArgs.reserve(InnerParams->size());
2173 
2174  // Later template parameters could refer to earlier ones, so build up
2175  // a list of substituted template arguments as we go.
2176  for (NamedDecl *Param : *InnerParams) {
2179  Args.addOuterTemplateArguments(SubstArgs);
2180  Args.addOuterRetainedLevel();
2181  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
2182  if (!NewParam)
2183  return nullptr;
2184  AllParams.push_back(NewParam);
2185  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
2186  SemaRef.Context.getInjectedTemplateArg(NewParam)));
2187  }
2188  TemplateParams = TemplateParameterList::Create(
2189  SemaRef.Context, InnerParams->getTemplateLoc(),
2190  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
2191  /*FIXME: RequiresClause*/ nullptr);
2192  }
2193 
2194  // If we built a new template-parameter-list, track that we need to
2195  // substitute references to the old parameters into references to the
2196  // new ones.
2199  if (FTD) {
2200  Args.addOuterTemplateArguments(SubstArgs);
2201  Args.addOuterRetainedLevel();
2202  }
2203 
2206  assert(FPTL && "no prototype for constructor declaration");
2207 
2208  // Transform the type of the function, adjusting the return type and
2209  // replacing references to the old parameters with references to the
2210  // new ones.
2211  TypeLocBuilder TLB;
2213  SmallVector<TypedefNameDecl *, 4> MaterializedTypedefs;
2214  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args,
2215  MaterializedTypedefs);
2216  if (NewType.isNull())
2217  return nullptr;
2218  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
2219 
2220  return buildDeductionGuide(TemplateParams, CD, CD->getExplicitSpecifier(),
2221  NewTInfo, CD->getBeginLoc(), CD->getLocation(),
2222  CD->getEndLoc(), MaterializedTypedefs);
2223  }
2224 
2225  /// Build a deduction guide with the specified parameter types.
2226  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
2227  SourceLocation Loc = Template->getLocation();
2228 
2229  // Build the requested type.
2231  EPI.HasTrailingReturn = true;
2232  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
2233  DeductionGuideName, EPI);
2234  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
2235 
2236  FunctionProtoTypeLoc FPTL =
2238 
2239  // Build the parameters, needed during deduction / substitution.
2241  for (auto T : ParamTypes) {
2242  ParmVarDecl *NewParam = ParmVarDecl::Create(
2243  SemaRef.Context, DC, Loc, Loc, nullptr, T,
2244  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
2245  NewParam->setScopeInfo(0, Params.size());
2246  FPTL.setParam(Params.size(), NewParam);
2247  Params.push_back(NewParam);
2248  }
2249 
2250  return buildDeductionGuide(Template->getTemplateParameters(), nullptr,
2251  ExplicitSpecifier(), TSI, Loc, Loc, Loc);
2252  }
2253 
2254 private:
2255  /// Transform a constructor template parameter into a deduction guide template
2256  /// parameter, rebuilding any internal references to earlier parameters and
2257  /// renumbering as we go.
2258  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
2260  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
2261  // TemplateTypeParmDecl's index cannot be changed after creation, so
2262  // substitute it directly.
2263  auto *NewTTP = TemplateTypeParmDecl::Create(
2264  SemaRef.Context, DC, TTP->getBeginLoc(), TTP->getLocation(),
2265  /*Depth*/ 0, Depth1IndexAdjustment + TTP->getIndex(),
2266  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
2267  TTP->isParameterPack(), TTP->hasTypeConstraint(),
2268  TTP->isExpandedParameterPack() ?
2269  llvm::Optional<unsigned>(TTP->getNumExpansionParameters()) : None);
2270  if (const auto *TC = TTP->getTypeConstraint()) {
2271  TemplateArgumentListInfo TransformedArgs;
2272  const auto *ArgsAsWritten = TC->getTemplateArgsAsWritten();
2273  if (!ArgsAsWritten ||
2274  SemaRef.Subst(ArgsAsWritten->getTemplateArgs(),
2275  ArgsAsWritten->NumTemplateArgs, TransformedArgs,
2276  Args))
2277  SemaRef.AttachTypeConstraint(
2278  TC->getNestedNameSpecifierLoc(), TC->getConceptNameInfo(),
2279  TC->getNamedConcept(), ArgsAsWritten ? &TransformedArgs : nullptr,
2280  NewTTP,
2281  NewTTP->isParameterPack()
2282  ? cast<CXXFoldExpr>(TC->getImmediatelyDeclaredConstraint())
2283  ->getEllipsisLoc()
2284  : SourceLocation());
2285  }
2286  if (TTP->hasDefaultArgument()) {
2287  TypeSourceInfo *InstantiatedDefaultArg =
2288  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
2289  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
2290  if (InstantiatedDefaultArg)
2291  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
2292  }
2293  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
2294  NewTTP);
2295  return NewTTP;
2296  }
2297 
2298  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
2299  return transformTemplateParameterImpl(TTP, Args);
2300 
2301  return transformTemplateParameterImpl(
2302  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
2303  }
2304  template<typename TemplateParmDecl>
2305  TemplateParmDecl *
2306  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
2308  // Ask the template instantiator to do the heavy lifting for us, then adjust
2309  // the index of the parameter once it's done.
2310  auto *NewParam =
2311  cast<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
2312  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
2313  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
2314  return NewParam;
2315  }
2316 
2317  QualType transformFunctionProtoType(
2321  SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2322  SmallVector<QualType, 4> ParamTypes;
2323  const FunctionProtoType *T = TL.getTypePtr();
2324 
2325  // -- The types of the function parameters are those of the constructor.
2326  for (auto *OldParam : TL.getParams()) {
2327  ParmVarDecl *NewParam =
2328  transformFunctionTypeParam(OldParam, Args, MaterializedTypedefs);
2329  if (!NewParam)
2330  return QualType();
2331  ParamTypes.push_back(NewParam->getType());
2332  Params.push_back(NewParam);
2333  }
2334 
2335  // -- The return type is the class template specialization designated by
2336  // the template-name and template arguments corresponding to the
2337  // template parameters obtained from the class template.
2338  //
2339  // We use the injected-class-name type of the primary template instead.
2340  // This has the convenient property that it is different from any type that
2341  // the user can write in a deduction-guide (because they cannot enter the
2342  // context of the template), so implicit deduction guides can never collide
2343  // with explicit ones.
2344  QualType ReturnType = DeducedType;
2345  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
2346 
2347  // Resolving a wording defect, we also inherit the variadicness of the
2348  // constructor.
2350  EPI.Variadic = T->isVariadic();
2351  EPI.HasTrailingReturn = true;
2352 
2353  QualType Result = SemaRef.BuildFunctionType(
2354  ReturnType, ParamTypes, TL.getBeginLoc(), DeductionGuideName, EPI);
2355  if (Result.isNull())
2356  return QualType();
2357 
2358  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
2360  NewTL.setLParenLoc(TL.getLParenLoc());
2361  NewTL.setRParenLoc(TL.getRParenLoc());
2363  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
2364  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
2365  NewTL.setParam(I, Params[I]);
2366 
2367  return Result;
2368  }
2369 
2370  ParmVarDecl *transformFunctionTypeParam(
2372  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2373  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
2374  TypeSourceInfo *NewDI;
2375  if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
2376  // Expand out the one and only element in each inner pack.
2377  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
2378  NewDI =
2379  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
2380  OldParam->getLocation(), OldParam->getDeclName());
2381  if (!NewDI) return nullptr;
2382  NewDI =
2383  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
2384  PackTL.getTypePtr()->getNumExpansions());
2385  } else
2386  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
2387  OldParam->getDeclName());
2388  if (!NewDI)
2389  return nullptr;
2390 
2391  // Extract the type. This (for instance) replaces references to typedef
2392  // members of the current instantiations with the definitions of those
2393  // typedefs, avoiding triggering instantiation of the deduced type during
2394  // deduction.
2395  NewDI = ExtractTypeForDeductionGuide(SemaRef, MaterializedTypedefs)
2396  .transform(NewDI);
2397 
2398  // Resolving a wording defect, we also inherit default arguments from the
2399  // constructor.
2400  ExprResult NewDefArg;
2401  if (OldParam->hasDefaultArg()) {
2402  // We don't care what the value is (we won't use it); just create a
2403  // placeholder to indicate there is a default argument.
2404  QualType ParamTy = NewDI->getType();
2405  NewDefArg = new (SemaRef.Context)
2406  OpaqueValueExpr(OldParam->getDefaultArg()->getBeginLoc(),
2407  ParamTy.getNonLValueExprType(SemaRef.Context),
2408  ParamTy->isLValueReferenceType() ? VK_LValue
2409  : ParamTy->isRValueReferenceType() ? VK_XValue
2410  : VK_PRValue);
2411  }
2412 
2413  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
2414  OldParam->getInnerLocStart(),
2415  OldParam->getLocation(),
2416  OldParam->getIdentifier(),
2417  NewDI->getType(),
2418  NewDI,
2419  OldParam->getStorageClass(),
2420  NewDefArg.get());
2421  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
2422  OldParam->getFunctionScopeIndex());
2423  SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
2424  return NewParam;
2425  }
2426 
2427  FunctionTemplateDecl *buildDeductionGuide(
2428  TemplateParameterList *TemplateParams, CXXConstructorDecl *Ctor,
2429  ExplicitSpecifier ES, TypeSourceInfo *TInfo, SourceLocation LocStart,
2430  SourceLocation Loc, SourceLocation LocEnd,
2431  llvm::ArrayRef<TypedefNameDecl *> MaterializedTypedefs = {}) {
2432  DeclarationNameInfo Name(DeductionGuideName, Loc);
2433  ArrayRef<ParmVarDecl *> Params =
2434  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
2435 
2436  // Build the implicit deduction guide template.
2437  auto *Guide =
2438  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, ES, Name,
2439  TInfo->getType(), TInfo, LocEnd, Ctor);
2440  Guide->setImplicit();
2441  Guide->setParams(Params);
2442 
2443  for (auto *Param : Params)
2444  Param->setDeclContext(Guide);
2445  for (auto *TD : MaterializedTypedefs)
2446  TD->setDeclContext(Guide);
2447 
2448  auto *GuideTemplate = FunctionTemplateDecl::Create(
2449  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
2450  GuideTemplate->setImplicit();
2451  Guide->setDescribedFunctionTemplate(GuideTemplate);
2452 
2453  if (isa<CXXRecordDecl>(DC)) {
2454  Guide->setAccess(AS_public);
2455  GuideTemplate->setAccess(AS_public);
2456  }
2457 
2458  DC->addDecl(GuideTemplate);
2459  return GuideTemplate;
2460  }
2461 };
2462 }
2463 
2465  SourceLocation Loc) {
2466  if (CXXRecordDecl *DefRecord =
2467  cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
2468  TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
2469  Template = DescribedTemplate ? DescribedTemplate : Template;
2470  }
2471 
2472  DeclContext *DC = Template->getDeclContext();
2473  if (DC->isDependentContext())
2474  return;
2475 
2476  ConvertConstructorToDeductionGuideTransform Transform(
2477  *this, cast<ClassTemplateDecl>(Template));
2478  if (!isCompleteType(Loc, Transform.DeducedType))
2479  return;
2480 
2481  // Check whether we've already declared deduction guides for this template.
2482  // FIXME: Consider storing a flag on the template to indicate this.
2483  auto Existing = DC->lookup(Transform.DeductionGuideName);
2484  for (auto *D : Existing)
2485  if (D->isImplicit())
2486  return;
2487 
2488  // In case we were expanding a pack when we attempted to declare deduction
2489  // guides, turn off pack expansion for everything we're about to do.
2490  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
2491  // Create a template instantiation record to track the "instantiation" of
2492  // constructors into deduction guides.
2493  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
2494  // this substitution process actually fail?
2495  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
2496  if (BuildingDeductionGuides.isInvalid())
2497  return;
2498 
2499  // Convert declared constructors into deduction guide templates.
2500  // FIXME: Skip constructors for which deduction must necessarily fail (those
2501  // for which some class template parameter without a default argument never
2502  // appears in a deduced context).
2503  bool AddedAny = false;
2504  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2505  D = D->getUnderlyingDecl();
2506  if (D->isInvalidDecl() || D->isImplicit())
2507  continue;
2508  D = cast<NamedDecl>(D->getCanonicalDecl());
2509 
2510  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2511  auto *CD =
2512  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2513  // Class-scope explicit specializations (MS extension) do not result in
2514  // deduction guides.
2515  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2516  continue;
2517 
2518  // Cannot make a deduction guide when unparsed arguments are present.
2519  if (std::any_of(CD->param_begin(), CD->param_end(), [](ParmVarDecl *P) {
2520  return !P || P->hasUnparsedDefaultArg();
2521  }))
2522  continue;
2523 
2524  Transform.transformConstructor(FTD, CD);
2525  AddedAny = true;
2526  }
2527 
2528  // C++17 [over.match.class.deduct]
2529  // -- If C is not defined or does not declare any constructors, an
2530  // additional function template derived as above from a hypothetical
2531  // constructor C().
2532  if (!AddedAny)
2533  Transform.buildSimpleDeductionGuide(None);
2534 
2535  // -- An additional function template derived as above from a hypothetical
2536  // constructor C(C), called the copy deduction candidate.
2537  cast<CXXDeductionGuideDecl>(
2538  cast<FunctionTemplateDecl>(
2539  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2540  ->getTemplatedDecl())
2541  ->setIsCopyDeductionCandidate();
2542 }
2543 
2544 /// Diagnose the presence of a default template argument on a
2545 /// template parameter, which is ill-formed in certain contexts.
2546 ///
2547 /// \returns true if the default template argument should be dropped.
2550  SourceLocation ParamLoc,
2551  SourceRange DefArgRange) {
2552  switch (TPC) {
2554  case Sema::TPC_VarTemplate:
2556  return false;
2557 
2560  // C++ [temp.param]p9:
2561  // A default template-argument shall not be specified in a
2562  // function template declaration or a function template
2563  // definition [...]
2564  // If a friend function template declaration specifies a default
2565  // template-argument, that declaration shall be a definition and shall be
2566  // the only declaration of the function template in the translation unit.
2567  // (C++98/03 doesn't have this wording; see DR226).
2568  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2569  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2570  : diag::ext_template_parameter_default_in_function_template)
2571  << DefArgRange;
2572  return false;
2573 
2575  // C++0x [temp.param]p9:
2576  // A default template-argument shall not be specified in the
2577  // template-parameter-lists of the definition of a member of a
2578  // class template that appears outside of the member's class.
2579  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2580  << DefArgRange;
2581  return true;
2582 
2585  // C++ [temp.param]p9:
2586  // A default template-argument shall not be specified in a
2587  // friend template declaration.
2588  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2589  << DefArgRange;
2590  return true;
2591 
2592  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2593  // for friend function templates if there is only a single
2594  // declaration (and it is a definition). Strange!
2595  }
2596 
2597  llvm_unreachable("Invalid TemplateParamListContext!");
2598 }
2599 
2600 /// Check for unexpanded parameter packs within the template parameters
2601 /// of a template template parameter, recursively.
2603  TemplateTemplateParmDecl *TTP) {
2604  // A template template parameter which is a parameter pack is also a pack
2605  // expansion.
2606  if (TTP->isParameterPack())
2607  return false;
2608 
2610  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2611  NamedDecl *P = Params->getParam(I);
2612  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(P)) {
2613  if (!TTP->isParameterPack())
2614  if (const TypeConstraint *TC = TTP->getTypeConstraint())
2615  if (TC->hasExplicitTemplateArgs())
2616  for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
2617  if (S.DiagnoseUnexpandedParameterPack(ArgLoc,
2619  return true;
2620  continue;
2621  }
2622 
2623  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2624  if (!NTTP->isParameterPack() &&
2625  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2626  NTTP->getTypeSourceInfo(),
2628  return true;
2629 
2630  continue;
2631  }
2632 
2633  if (TemplateTemplateParmDecl *InnerTTP
2634  = dyn_cast<TemplateTemplateParmDecl>(P))
2635  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2636  return true;
2637  }
2638 
2639  return false;
2640 }
2641 
2642 /// Checks the validity of a template parameter list, possibly
2643 /// considering the template parameter list from a previous
2644 /// declaration.
2645 ///
2646 /// If an "old" template parameter list is provided, it must be
2647 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2648 /// template parameter list.
2649 ///
2650 /// \param NewParams Template parameter list for a new template
2651 /// declaration. This template parameter list will be updated with any
2652 /// default arguments that are carried through from the previous
2653 /// template parameter list.
2654 ///
2655 /// \param OldParams If provided, template parameter list from a
2656 /// previous declaration of the same template. Default template
2657 /// arguments will be merged from the old template parameter list to
2658 /// the new template parameter list.
2659 ///
2660 /// \param TPC Describes the context in which we are checking the given
2661 /// template parameter list.
2662 ///
2663 /// \param SkipBody If we might have already made a prior merged definition
2664 /// of this template visible, the corresponding body-skipping information.
2665 /// Default argument redefinition is not an error when skipping such a body,
2666 /// because (under the ODR) we can assume the default arguments are the same
2667 /// as the prior merged definition.
2668 ///
2669 /// \returns true if an error occurred, false otherwise.
2671  TemplateParameterList *OldParams,
2673  SkipBodyInfo *SkipBody) {
2674  bool Invalid = false;
2675 
2676  // C++ [temp.param]p10:
2677  // The set of default template-arguments available for use with a
2678  // template declaration or definition is obtained by merging the
2679  // default arguments from the definition (if in scope) and all
2680  // declarations in scope in the same way default function
2681  // arguments are (8.3.6).
2682  bool SawDefaultArgument = false;
2683  SourceLocation PreviousDefaultArgLoc;
2684 
2685  // Dummy initialization to avoid warnings.
2686  TemplateParameterList::iterator OldParam = NewParams->end();
2687  if (OldParams)
2688  OldParam = OldParams->begin();
2689 
2690  bool RemoveDefaultArguments = false;
2691  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2692  NewParamEnd = NewParams->end();
2693  NewParam != NewParamEnd; ++NewParam) {
2694  // Variables used to diagnose redundant default arguments
2695  bool RedundantDefaultArg = false;
2696  SourceLocation OldDefaultLoc;
2697  SourceLocation NewDefaultLoc;
2698 
2699  // Variable used to diagnose missing default arguments
2700  bool MissingDefaultArg = false;
2701 
2702  // Variable used to diagnose non-final parameter packs
2703  bool SawParameterPack = false;
2704 
2705  if (TemplateTypeParmDecl *NewTypeParm
2706  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2707  // Check the presence of a default argument here.
2708  if (NewTypeParm->hasDefaultArgument() &&
2710  NewTypeParm->getLocation(),
2711  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2712  .getSourceRange()))
2713  NewTypeParm->removeDefaultArgument();
2714 
2715  // Merge default arguments for template type parameters.
2716  TemplateTypeParmDecl *OldTypeParm
2717  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2718  if (NewTypeParm->isParameterPack()) {
2719  assert(!NewTypeParm->hasDefaultArgument() &&
2720  "Parameter packs can't have a default argument!");
2721  SawParameterPack = true;
2722  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2723  NewTypeParm->hasDefaultArgument() &&
2724  (!SkipBody || !SkipBody->ShouldSkip)) {
2725  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2726  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2727  SawDefaultArgument = true;
2728  RedundantDefaultArg = true;
2729  PreviousDefaultArgLoc = NewDefaultLoc;
2730  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2731  // Merge the default argument from the old declaration to the
2732  // new declaration.
2733  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2734  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2735  } else if (NewTypeParm->hasDefaultArgument()) {
2736  SawDefaultArgument = true;
2737  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2738  } else if (SawDefaultArgument)
2739  MissingDefaultArg = true;
2740  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2741  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2742  // Check for unexpanded parameter packs.
2743  if (!NewNonTypeParm->isParameterPack() &&
2744  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2745  NewNonTypeParm->getTypeSourceInfo(),
2746  UPPC_NonTypeTemplateParameterType)) {
2747  Invalid = true;
2748  continue;
2749  }
2750 
2751  // Check the presence of a default argument here.
2752  if (NewNonTypeParm->hasDefaultArgument() &&
2754  NewNonTypeParm->getLocation(),
2755  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2756  NewNonTypeParm->removeDefaultArgument();
2757  }
2758 
2759  // Merge default arguments for non-type template parameters
2760  NonTypeTemplateParmDecl *OldNonTypeParm
2761  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2762  if (NewNonTypeParm->isParameterPack()) {
2763  assert(!NewNonTypeParm->hasDefaultArgument() &&
2764  "Parameter packs can't have a default argument!");
2765  if (!NewNonTypeParm->isPackExpansion())
2766  SawParameterPack = true;
2767  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2768  NewNonTypeParm->hasDefaultArgument() &&
2769  (!SkipBody || !SkipBody->ShouldSkip)) {
2770  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2771  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2772  SawDefaultArgument = true;
2773  RedundantDefaultArg = true;
2774  PreviousDefaultArgLoc = NewDefaultLoc;
2775  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2776  // Merge the default argument from the old declaration to the
2777  // new declaration.
2778  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2779  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2780  } else if (NewNonTypeParm->hasDefaultArgument()) {
2781  SawDefaultArgument = true;
2782  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2783  } else if (SawDefaultArgument)
2784  MissingDefaultArg = true;
2785  } else {
2786  TemplateTemplateParmDecl *NewTemplateParm
2787  = cast<TemplateTemplateParmDecl>(*NewParam);
2788 
2789  // Check for unexpanded parameter packs, recursively.
2790  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2791  Invalid = true;
2792  continue;
2793  }
2794 
2795  // Check the presence of a default argument here.
2796  if (NewTemplateParm->hasDefaultArgument() &&
2798  NewTemplateParm->getLocation(),
2799  NewTemplateParm->getDefaultArgument().getSourceRange()))
2800  NewTemplateParm->removeDefaultArgument();
2801 
2802  // Merge default arguments for template template parameters
2803  TemplateTemplateParmDecl *OldTemplateParm
2804  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2805  if (NewTemplateParm->isParameterPack()) {
2806  assert(!NewTemplateParm->hasDefaultArgument() &&
2807  "Parameter packs can't have a default argument!");
2808  if (!NewTemplateParm->isPackExpansion())
2809  SawParameterPack = true;
2810  } else if (OldTemplateParm &&
2811  hasVisibleDefaultArgument(OldTemplateParm) &&
2812  NewTemplateParm->hasDefaultArgument() &&
2813  (!SkipBody || !SkipBody->ShouldSkip)) {
2814  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2815  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2816  SawDefaultArgument = true;
2817  RedundantDefaultArg = true;
2818  PreviousDefaultArgLoc = NewDefaultLoc;
2819  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2820  // Merge the default argument from the old declaration to the
2821  // new declaration.
2822  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2823  PreviousDefaultArgLoc
2824  = OldTemplateParm->getDefaultArgument().getLocation();
2825  } else if (NewTemplateParm->hasDefaultArgument()) {
2826  SawDefaultArgument = true;
2827  PreviousDefaultArgLoc
2828  = NewTemplateParm->getDefaultArgument().getLocation();
2829  } else if (SawDefaultArgument)
2830  MissingDefaultArg = true;
2831  }
2832 
2833  // C++11 [temp.param]p11:
2834  // If a template parameter of a primary class template or alias template
2835  // is a template parameter pack, it shall be the last template parameter.
2836  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2837  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2838  TPC == TPC_TypeAliasTemplate)) {
2839  Diag((*NewParam)->getLocation(),
2840  diag::err_template_param_pack_must_be_last_template_parameter);
2841  Invalid = true;
2842  }
2843 
2844  if (RedundantDefaultArg) {
2845  // C++ [temp.param]p12:
2846  // A template-parameter shall not be given default arguments
2847  // by two different declarations in the same scope.
2848  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2849  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2850  Invalid = true;
2851  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2852  // C++ [temp.param]p11:
2853  // If a template-parameter of a class template has a default
2854  // template-argument, each subsequent template-parameter shall either
2855  // have a default template-argument supplied or be a template parameter
2856  // pack.
2857  Diag((*NewParam)->getLocation(),
2858  diag::err_template_param_default_arg_missing);
2859  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2860  Invalid = true;
2861  RemoveDefaultArguments = true;
2862  }
2863 
2864  // If we have an old template parameter list that we're merging
2865  // in, move on to the next parameter.
2866  if (OldParams)
2867  ++OldParam;
2868  }
2869 
2870  // We were missing some default arguments at the end of the list, so remove
2871  // all of the default arguments.
2872  if (RemoveDefaultArguments) {
2873  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2874  NewParamEnd = NewParams->end();
2875  NewParam != NewParamEnd; ++NewParam) {
2876  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2877  TTP->removeDefaultArgument();
2878  else if (NonTypeTemplateParmDecl *NTTP
2879  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2880  NTTP->removeDefaultArgument();
2881  else
2882  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2883  }
2884  }
2885 
2886  return Invalid;
2887 }
2888 
2889 namespace {
2890 
2891 /// A class which looks for a use of a certain level of template
2892 /// parameter.
2893 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2895 
2896  unsigned Depth;
2897 
2898  // Whether we're looking for a use of a template parameter that makes the
2899  // overall construct type-dependent / a dependent type. This is strictly
2900  // best-effort for now; we may fail to match at all for a dependent type
2901  // in some cases if this is set.
2902  bool IgnoreNonTypeDependent;
2903 
2904  bool Match;
2905  SourceLocation MatchLoc;
2906 
2907  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2908  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2909  Match(false) {}
2910 
2911  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2912  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2913  NamedDecl *ND = Params->getParam(0);
2914  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2915  Depth = PD->getDepth();
2916  } else if (NonTypeTemplateParmDecl *PD =
2917  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2918  Depth = PD->getDepth();
2919  } else {
2920  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2921  }
2922  }
2923 
2924  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2925  if (ParmDepth >= Depth) {
2926  Match = true;
2927  MatchLoc = Loc;
2928  return true;
2929  }
2930  return false;
2931  }
2932 
2933  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2934  // Prune out non-type-dependent expressions if requested. This can
2935  // sometimes result in us failing to find a template parameter reference
2936  // (if a value-dependent expression creates a dependent type), but this
2937  // mode is best-effort only.
2938  if (auto *E = dyn_cast_or_null<Expr>(S))
2939  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2940  return true;
2941  return super::TraverseStmt(S, Q);
2942  }
2943 
2944  bool TraverseTypeLoc(TypeLoc TL) {
2945  if (IgnoreNonTypeDependent && !TL.isNull() &&
2946  !TL.getType()->isDependentType())
2947  return true;
2948  return super::TraverseTypeLoc(TL);
2949  }
2950 
2951  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2952  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2953  }
2954 
2955  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2956  // For a best-effort search, keep looking until we find a location.
2957  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2958  }
2959 
2960  bool TraverseTemplateName(TemplateName N) {
2961  if (TemplateTemplateParmDecl *PD =
2962  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2963  if (Matches(PD->getDepth()))
2964  return false;
2965  return super::TraverseTemplateName(N);
2966  }
2967 
2968  bool VisitDeclRefExpr(DeclRefExpr *E) {
2969  if (NonTypeTemplateParmDecl *PD =
2970  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2971  if (Matches(PD->getDepth(), E->getExprLoc()))
2972  return false;
2973  return super::VisitDeclRefExpr(E);
2974  }
2975 
2976  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2977  return TraverseType(T->getReplacementType());
2978  }
2979 
2980  bool
2981  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2982  return TraverseTemplateArgument(T->getArgumentPack());
2983  }
2984 
2985  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2986  return TraverseType(T->getInjectedSpecializationType());
2987  }
2988 };
2989 } // end anonymous namespace
2990 
2991 /// Determines whether a given type depends on the given parameter
2992 /// list.
2993 static bool
2995  if (!Params->size())
2996  return false;
2997 
2998  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2999  Checker.TraverseType(T);
3000  return Checker.Match;
3001 }
3002 
3003 // Find the source range corresponding to the named type in the given
3004 // nested-name-specifier, if any.
3006  QualType T,
3007  const CXXScopeSpec &SS) {
3009  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
3010  if (const Type *CurType = NNS->getAsType()) {
3011  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
3012  return NNSLoc.getTypeLoc().getSourceRange();
3013  } else
3014  break;
3015 
3016  NNSLoc = NNSLoc.getPrefix();
3017  }
3018 
3019  return SourceRange();
3020 }
3021 
3022 /// Match the given template parameter lists to the given scope
3023 /// specifier, returning the template parameter list that applies to the
3024 /// name.
3025 ///
3026 /// \param DeclStartLoc the start of the declaration that has a scope
3027 /// specifier or a template parameter list.
3028 ///
3029 /// \param DeclLoc The location of the declaration itself.
3030 ///
3031 /// \param SS the scope specifier that will be matched to the given template
3032 /// parameter lists. This scope specifier precedes a qualified name that is
3033 /// being declared.
3034 ///
3035 /// \param TemplateId The template-id following the scope specifier, if there
3036 /// is one. Used to check for a missing 'template<>'.
3037 ///
3038 /// \param ParamLists the template parameter lists, from the outermost to the
3039 /// innermost template parameter lists.
3040 ///
3041 /// \param IsFriend Whether to apply the slightly different rules for
3042 /// matching template parameters to scope specifiers in friend
3043 /// declarations.
3044 ///
3045 /// \param IsMemberSpecialization will be set true if the scope specifier
3046 /// denotes a fully-specialized type, and therefore this is a declaration of
3047 /// a member specialization.
3048 ///
3049 /// \returns the template parameter list, if any, that corresponds to the
3050 /// name that is preceded by the scope specifier @p SS. This template
3051 /// parameter list may have template parameters (if we're declaring a
3052 /// template) or may have no template parameters (if we're declaring a
3053 /// template specialization), or may be NULL (if what we're declaring isn't
3054 /// itself a template).
3056  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
3057  TemplateIdAnnotation *TemplateId,
3058  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
3059  bool &IsMemberSpecialization, bool &Invalid, bool SuppressDiagnostic) {
3060  IsMemberSpecialization = false;
3061  Invalid = false;
3062 
3063  // The sequence of nested types to which we will match up the template
3064  // parameter lists. We first build this list by starting with the type named
3065  // by the nested-name-specifier and walking out until we run out of types.
3066  SmallVector<QualType, 4> NestedTypes;
3067  QualType T;
3068  if (SS.getScopeRep()) {
3069  if (CXXRecordDecl *Record
3070  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
3071  T = Context.getTypeDeclType(Record);
3072  else
3073  T = QualType(SS.getScopeRep()->getAsType(), 0);
3074  }
3075 
3076  // If we found an explicit specialization that prevents us from needing
3077  // 'template<>' headers, this will be set to the location of that
3078  // explicit specialization.
3079  SourceLocation ExplicitSpecLoc;
3080 
3081  while (!T.isNull()) {
3082  NestedTypes.push_back(T);
3083 
3084  // Retrieve the parent of a record type.
3085  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3086  // If this type is an explicit specialization, we're done.
3088  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3089  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
3090  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
3091  ExplicitSpecLoc = Spec->getLocation();
3092  break;
3093  }
3094  } else if (Record->getTemplateSpecializationKind()
3096  ExplicitSpecLoc = Record->getLocation();
3097  break;
3098  }
3099 
3100  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
3101  T = Context.getTypeDeclType(Parent);
3102  else
3103  T = QualType();
3104  continue;
3105  }
3106 
3107  if (const TemplateSpecializationType *TST
3109  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3110  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
3111  T = Context.getTypeDeclType(Parent);
3112  else
3113  T = QualType();
3114  continue;
3115  }
3116  }
3117 
3118  // Look one step prior in a dependent template specialization type.
3119  if (const DependentTemplateSpecializationType *DependentTST
3121  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
3122  T = QualType(NNS->getAsType(), 0);
3123  else
3124  T = QualType();
3125  continue;
3126  }
3127 
3128  // Look one step prior in a dependent name type.
3129  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
3130  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
3131  T = QualType(NNS->getAsType(), 0);
3132  else
3133  T = QualType();
3134  continue;
3135  }
3136 
3137  // Retrieve the parent of an enumeration type.
3138  if (const EnumType *EnumT = T->getAs<EnumType>()) {
3139  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
3140  // check here.
3141  EnumDecl *Enum = EnumT->getDecl();
3142 
3143  // Get to the parent type.
3144  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
3145  T = Context.getTypeDeclType(Parent);
3146  else
3147  T = QualType();
3148  continue;
3149  }
3150 
3151  T = QualType();
3152  }
3153  // Reverse the nested types list, since we want to traverse from the outermost
3154  // to the innermost while checking template-parameter-lists.
3155  std::reverse(NestedTypes.begin(), NestedTypes.end());
3156 
3157  // C++0x [temp.expl.spec]p17:
3158  // A member or a member template may be nested within many
3159  // enclosing class templates. In an explicit specialization for
3160  // such a member, the member declaration shall be preceded by a
3161  // template<> for each enclosing class template that is
3162  // explicitly specialized.
3163  bool SawNonEmptyTemplateParameterList = false;
3164 
3165  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
3166  if (SawNonEmptyTemplateParameterList) {
3167  if (!SuppressDiagnostic)
3168  Diag(DeclLoc, diag::err_specialize_member_of_template)
3169  << !Recovery << Range;
3170  Invalid = true;
3171  IsMemberSpecialization = false;
3172  return true;
3173  }
3174 
3175  return false;
3176  };
3177 
3178  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
3179  // Check that we can have an explicit specialization here.
3180  if (CheckExplicitSpecialization(Range, true))
3181  return true;
3182 
3183  // We don't have a template header, but we should.
3184  SourceLocation ExpectedTemplateLoc;
3185  if (!ParamLists.empty())
3186  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
3187  else
3188  ExpectedTemplateLoc = DeclStartLoc;
3189 
3190  if (!SuppressDiagnostic)
3191  Diag(DeclLoc, diag::err_template_spec_needs_header)
3192  << Range
3193  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
3194  return false;
3195  };
3196 
3197  unsigned ParamIdx = 0;
3198  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
3199  ++TypeIdx) {
3200  T = NestedTypes[TypeIdx];
3201 
3202  // Whether we expect a 'template<>' header.
3203  bool NeedEmptyTemplateHeader = false;
3204 
3205  // Whether we expect a template header with parameters.
3206  bool NeedNonemptyTemplateHeader = false;
3207 
3208  // For a dependent type, the set of template parameters that we
3209  // expect to see.
3210  TemplateParameterList *ExpectedTemplateParams = nullptr;
3211 
3212  // C++0x [temp.expl.spec]p15:
3213  // A member or a member template may be nested within many enclosing
3214  // class templates. In an explicit specialization for such a member, the
3215  // member declaration shall be preceded by a template<> for each
3216  // enclosing class template that is explicitly specialized.
3217  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3219  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
3220  ExpectedTemplateParams = Partial->getTemplateParameters();
3221  NeedNonemptyTemplateHeader = true;
3222  } else if (Record->isDependentType()) {
3223  if (Record->getDescribedClassTemplate()) {
3224  ExpectedTemplateParams = Record->getDescribedClassTemplate()
3225  ->getTemplateParameters();
3226  NeedNonemptyTemplateHeader = true;
3227  }
3228  } else if (ClassTemplateSpecializationDecl *Spec
3229  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3230  // C++0x [temp.expl.spec]p4:
3231  // Members of an explicitly specialized class template are defined
3232  // in the same manner as members of normal classes, and not using
3233  // the template<> syntax.
3234  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
3235  NeedEmptyTemplateHeader = true;
3236  else
3237  continue;
3238  } else if (Record->getTemplateSpecializationKind()) {
3239  if (Record->getTemplateSpecializationKind()
3241  TypeIdx == NumTypes - 1)
3242  IsMemberSpecialization = true;
3243 
3244  continue;
3245  }
3246  } else if (const TemplateSpecializationType *TST
3248  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3249  ExpectedTemplateParams = Template->getTemplateParameters();
3250  NeedNonemptyTemplateHeader = true;
3251  }
3252  } else if (T->getAs<DependentTemplateSpecializationType>()) {
3253  // FIXME: We actually could/should check the template arguments here
3254  // against the corresponding template parameter list.
3255  NeedNonemptyTemplateHeader = false;
3256  }
3257 
3258  // C++ [temp.expl.spec]p16:
3259  // In an explicit specialization declaration for a member of a class
3260  // template or a member template that ap- pears in namespace scope, the
3261  // member template and some of its enclosing class templates may remain
3262  // unspecialized, except that the declaration shall not explicitly
3263  // specialize a class member template if its en- closing class templates
3264  // are not explicitly specialized as well.
3265  if (ParamIdx < ParamLists.size()) {
3266  if (ParamLists[ParamIdx]->size() == 0) {
3267  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3268  false))
3269  return nullptr;
3270  } else
3271  SawNonEmptyTemplateParameterList = true;
3272  }
3273 
3274  if (NeedEmptyTemplateHeader) {
3275  // If we're on the last of the types, and we need a 'template<>' header
3276  // here, then it's a member specialization.
3277  if (TypeIdx == NumTypes - 1)
3278  IsMemberSpecialization = true;
3279 
3280  if (ParamIdx < ParamLists.size()) {
3281  if (ParamLists[ParamIdx]->size() > 0) {
3282  // The header has template parameters when it shouldn't. Complain.
3283  if (!SuppressDiagnostic)
3284  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3285  diag::err_template_param_list_matches_nontemplate)
3286  << T
3287  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
3288  ParamLists[ParamIdx]->getRAngleLoc())
3289  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3290  Invalid = true;
3291  return nullptr;
3292  }
3293 
3294  // Consume this template header.
3295  ++ParamIdx;
3296  continue;
3297  }
3298 
3299  if (!IsFriend)
3300  if (DiagnoseMissingExplicitSpecialization(
3301  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
3302  return nullptr;
3303 
3304  continue;
3305  }
3306 
3307  if (NeedNonemptyTemplateHeader) {
3308  // In friend declarations we can have template-ids which don't
3309  // depend on the corresponding template parameter lists. But
3310  // assume that empty parameter lists are supposed to match this
3311  // template-id.
3312  if (IsFriend && T->isDependentType()) {
3313  if (ParamIdx < ParamLists.size() &&
3314  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
3315  ExpectedTemplateParams = nullptr;
3316  else
3317  continue;
3318  }
3319 
3320  if (ParamIdx < ParamLists.size()) {
3321  // Check the template parameter list, if we can.
3322  if (ExpectedTemplateParams &&
3323  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
3324  ExpectedTemplateParams,
3325  !SuppressDiagnostic, TPL_TemplateMatch))
3326  Invalid = true;
3327 
3328  if (!Invalid &&
3329  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
3330  TPC_ClassTemplateMember))
3331  Invalid = true;
3332 
3333  ++ParamIdx;
3334  continue;
3335  }
3336 
3337  if (!SuppressDiagnostic)
3338  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
3339  << T
3340  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3341  Invalid = true;
3342  continue;
3343  }
3344  }
3345 
3346  // If there were at least as many template-ids as there were template
3347  // parameter lists, then there are no template parameter lists remaining for
3348  // the declaration itself.
3349  if (ParamIdx >= ParamLists.size()) {
3350  if (TemplateId && !IsFriend) {
3351  // We don't have a template header for the declaration itself, but we
3352  // should.
3353  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
3354  TemplateId->RAngleLoc));
3355 
3356  // Fabricate an empty template parameter list for the invented header.
3358  SourceLocation(), None,
3359  SourceLocation(), nullptr);
3360  }
3361 
3362  return nullptr;
3363  }
3364 
3365  // If there were too many template parameter lists, complain about that now.
3366  if (ParamIdx < ParamLists.size() - 1) {
3367  bool HasAnyExplicitSpecHeader = false;
3368  bool AllExplicitSpecHeaders = true;
3369  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
3370  if (ParamLists[I]->size() == 0)
3371  HasAnyExplicitSpecHeader = true;
3372  else
3373  AllExplicitSpecHeaders = false;
3374  }
3375 
3376  if (!SuppressDiagnostic)
3377  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3378  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
3379  : diag::err_template_spec_extra_headers)
3380  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
3381  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
3382 
3383  // If there was a specialization somewhere, such that 'template<>' is
3384  // not required, and there were any 'template<>' headers, note where the
3385  // specialization occurred.
3386  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader &&
3387  !SuppressDiagnostic)
3388  Diag(ExplicitSpecLoc,
3389  diag::note_explicit_template_spec_does_not_need_header)
3390  << NestedTypes.back();
3391 
3392  // We have a template parameter list with no corresponding scope, which
3393  // means that the resulting template declaration can't be instantiated
3394  // properly (we'll end up with dependent nodes when we shouldn't).
3395  if (!AllExplicitSpecHeaders)
3396  Invalid = true;
3397  }
3398 
3399  // C++ [temp.expl.spec]p16:
3400  // In an explicit specialization declaration for a member of a class
3401  // template or a member template that ap- pears in namespace scope, the
3402  // member template and some of its enclosing class templates may remain
3403  // unspecialized, except that the declaration shall not explicitly
3404  // specialize a class member template if its en- closing class templates
3405  // are not explicitly specialized as well.
3406  if (ParamLists.back()->size() == 0 &&
3407  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3408  false))
3409  return nullptr;
3410 
3411  // Return the last template parameter list, which corresponds to the
3412  // entity being declared.
3413  return ParamLists.back();
3414 }
3415 
3417  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
3418  Diag(Template->getLocation(), diag::note_template_declared_here)
3419  << (isa<FunctionTemplateDecl>(Template)
3420  ? 0
3421  : isa<ClassTemplateDecl>(Template)
3422  ? 1
3423  : isa<VarTemplateDecl>(Template)
3424  ? 2
3425  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
3426  << Template->getDeclName();
3427  return;
3428  }
3429 
3430  if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
3431  for (OverloadedTemplateStorage::iterator I = OST->begin(),
3432  IEnd = OST->end();
3433  I != IEnd; ++I)
3434  Diag((*I)->getLocation(), diag::note_template_declared_here)
3435  << 0 << (*I)->getDeclName();
3436 
3437  return;
3438  }
3439 }
3440 
3441 static QualType
3443  const SmallVectorImpl<TemplateArgument> &Converted,
3444  SourceLocation TemplateLoc,
3445  TemplateArgumentListInfo &TemplateArgs) {
3446  ASTContext &Context = SemaRef.getASTContext();
3447  switch (BTD->getBuiltinTemplateKind()) {
3448  case BTK__make_integer_seq: {
3449  // Specializations of __make_integer_seq<S, T, N> are treated like
3450  // S<T, 0, ..., N-1>.
3451 
3452  // C++14 [inteseq.intseq]p1:
3453  // T shall be an integer type.
3454  if (!Converted[1].getAsType()->isIntegralType(Context)) {
3455  SemaRef.Diag(TemplateArgs[1].getLocation(),
3456  diag::err_integer_sequence_integral_element_type);
3457  return QualType();
3458  }
3459 
3460  // C++14 [inteseq.make]p1:
3461  // If N is negative the program is ill-formed.
3462  TemplateArgument NumArgsArg = Converted[2];
3463  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
3464  if (NumArgs < 0) {
3465  SemaRef.Diag(TemplateArgs[2].getLocation(),
3466  diag::err_integer_sequence_negative_length);
3467  return QualType();
3468  }
3469 
3470  QualType ArgTy = NumArgsArg.getIntegralType();
3471  TemplateArgumentListInfo SyntheticTemplateArgs;
3472  // The type argument gets reused as the first template argument in the
3473  // synthetic template argument list.
3474  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
3475  // Expand N into 0 ... N-1.
3476  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
3477  I < NumArgs; ++I) {
3478  TemplateArgument TA(Context, I, ArgTy);
3479  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
3480  TA, ArgTy, TemplateArgs[2].getLocation()));
3481  }
3482  // The first template argument will be reused as the template decl that
3483  // our synthetic template arguments will be applied to.
3484  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
3485  TemplateLoc, SyntheticTemplateArgs);
3486  }
3487 
3489  // Specializations of
3490  // __type_pack_element<Index, T_1, ..., T_N>
3491  // are treated like T_Index.
3492  assert(Converted.size() == 2 &&
3493  "__type_pack_element should be given an index and a parameter pack");
3494 
3495  // If the Index is out of bounds, the program is ill-formed.
3496  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
3497  llvm::APSInt Index = IndexArg.getAsIntegral();
3498  assert(Index >= 0 && "the index used with __type_pack_element should be of "
3499  "type std::size_t, and hence be non-negative");
3500  if (Index >= Ts.pack_size()) {
3501  SemaRef.Diag(TemplateArgs[0].getLocation(),
3502  diag::err_type_pack_element_out_of_bounds);
3503  return QualType();
3504  }
3505 
3506  // We simply return the type at index `Index`.
3507  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
3508  return Nth->getAsType();
3509  }
3510  llvm_unreachable("unexpected BuiltinTemplateDecl!");
3511 }
3512 
3513 /// Determine whether this alias template is "enable_if_t".
3514 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3515  return AliasTemplate->getName().equals("enable_if_t");
3516 }
3517 
3518 /// Collect all of the separable terms in the given condition, which
3519 /// might be a conjunction.
3520 ///
3521 /// FIXME: The right answer is to convert the logical expression into
3522 /// disjunctive normal form, so we can find the first failed term
3523 /// within each possible clause.
3524 static void collectConjunctionTerms(Expr *Clause,
3525  SmallVectorImpl<Expr *> &Terms) {
3526  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3527  if (BinOp->getOpcode() == BO_LAnd) {
3528  collectConjunctionTerms(BinOp->getLHS(), Terms);
3529  collectConjunctionTerms(BinOp->getRHS(), Terms);
3530  }
3531 
3532  return;
3533  }
3534 
3535  Terms.push_back(Clause);
3536 }
3537 
3538 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3539 // a left-hand side that is value-dependent but never true. Identify
3540 // the idiom and ignore that term.
3542  // Top-level '||'.
3543  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3544  if (!BinOp) return Cond;
3545 
3546  if (BinOp->getOpcode() != BO_LOr) return Cond;
3547 
3548  // With an inner '==' that has a literal on the right-hand side.
3549  Expr *LHS = BinOp->getLHS();
3550  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3551  if (!InnerBinOp) return Cond;
3552 
3553  if (InnerBinOp->getOpcode() != BO_EQ ||
3554  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3555  return Cond;
3556 
3557  // If the inner binary operation came from a macro expansion named
3558  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3559  // of the '||', which is the real, user-provided condition.
3560  SourceLocation Loc = InnerBinOp->getExprLoc();
3561  if (!Loc.isMacroID()) return Cond;
3562 
3563  StringRef MacroName = PP.getImmediateMacroName(Loc);
3564  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3565  return BinOp->getRHS();
3566 
3567  return Cond;
3568 }
3569 
3570 namespace {
3571 
3572 // A PrinterHelper that prints more helpful diagnostics for some sub-expressions
3573 // within failing boolean expression, such as substituting template parameters
3574 // for actual types.
3575 class FailedBooleanConditionPrinterHelper : public PrinterHelper {
3576 public:
3577  explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
3578  : Policy(P) {}
3579 
3580  bool handledStmt(Stmt *E, raw_ostream &OS) override {
3581  const auto *DR = dyn_cast<DeclRefExpr>(E);
3582  if (DR && DR->getQualifier()) {
3583  // If this is a qualified name, expand the template arguments in nested
3584  // qualifiers.
3585  DR->getQualifier()->print(OS, Policy, true);
3586  // Then print the decl itself.
3587  const ValueDecl *VD = DR->getDecl();
3588  OS << VD->getName();
3589  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3590  // This is a template variable, print the expanded template arguments.
3592  OS, IV->getTemplateArgs().asArray(), Policy,
3593  IV->getSpecializedTemplate()->getTemplateParameters());
3594  }
3595  return true;
3596  }
3597  return false;
3598  }
3599 
3600 private:
3601  const PrintingPolicy Policy;
3602 };
3603 
3604 } // end anonymous namespace
3605 
3606 std::pair<Expr *, std::string>
3608  Cond = lookThroughRangesV3Condition(PP, Cond);
3609 
3610  // Separate out all of the terms in a conjunction.
3611  SmallVector<Expr *, 4> Terms;
3612  collectConjunctionTerms(Cond, Terms);
3613 
3614  // Determine which term failed.
3615  Expr *FailedCond = nullptr;
3616  for (Expr *Term : Terms) {
3617  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3618 
3619  // Literals are uninteresting.
3620  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3621  isa<IntegerLiteral>(TermAsWritten))
3622  continue;
3623 
3624  // The initialization of the parameter from the argument is
3625  // a constant-evaluated context.
3626  EnterExpressionEvaluationContext ConstantEvaluated(
3628 
3629  bool Succeeded;
3630  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3631  !Succeeded) {
3632  FailedCond = TermAsWritten;
3633  break;
3634  }
3635  }
3636  if (!FailedCond)
3637  FailedCond = Cond->IgnoreParenImpCasts();
3638 
3639  std::string Description;
3640  {
3641  llvm::raw_string_ostream Out(Description);
3642  PrintingPolicy Policy = getPrintingPolicy();
3643  Policy.PrintCanonicalTypes = true;
3644  FailedBooleanConditionPrinterHelper Helper(Policy);
3645  FailedCond->printPretty(Out, &Helper, Policy, 0, "\n", nullptr);
3646  }
3647  return { FailedCond, Description };
3648 }
3649 
3651  SourceLocation TemplateLoc,
3652  TemplateArgumentListInfo &TemplateArgs) {
3654  = Name.getUnderlying().getAsDependentTemplateName();
3655  if (DTN && DTN->isIdentifier())
3656  // When building a template-id where the template-name is dependent,
3657  // assume the template is a type template. Either our assumption is
3658  // correct, or the code is ill-formed and will be diagnosed when the
3659  // dependent name is substituted.
3661  DTN->getQualifier(),
3662  DTN->getIdentifier(),
3663  TemplateArgs);
3664 
3665  if (Name.getAsAssumedTemplateName() &&
3666  resolveAssumedTemplateNameAsType(/*Scope*/nullptr, Name, TemplateLoc))
3667  return QualType();
3668 
3669  TemplateDecl *Template = Name.getAsTemplateDecl();
3670  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3671  isa<VarTemplateDecl>(Template) || isa<ConceptDecl>(Template)) {
3672  // We might have a substituted template template parameter pack. If so,
3673  // build a template specialization type for it.
3674  if (Name.getAsSubstTemplateTemplateParmPack())
3675  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3676 
3677  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3678  << Name;
3679  NoteAllFoundTemplates(Name);
3680  return QualType();
3681  }
3682 
3683  // Check that the template argument list is well-formed for this
3684  // template.
3686  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3687  false, Converted,
3688  /*UpdateArgsWithConversion=*/true))
3689  return QualType();
3690 
3691  QualType CanonType;
3692 
3694  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3695 
3696  // Find the canonical type for this type alias template specialization.
3697  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3698  if (Pattern->isInvalidDecl())
3699  return QualType();
3700 
3702  Converted);
3703 
3704  // Only substitute for the innermost template argument list.
3705  MultiLevelTemplateArgumentList TemplateArgLists;
3706  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3707  TemplateArgLists.addOuterRetainedLevels(
3708  AliasTemplate->getTemplateParameters()->getDepth());
3709 
3711  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3712  if (Inst.isInvalid())
3713  return QualType();
3714 
3715  CanonType = SubstType(Pattern->getUnderlyingType(),
3716  TemplateArgLists, AliasTemplate->getLocation(),
3717  AliasTemplate->getDeclName());
3718  if (CanonType.isNull()) {
3719  // If this was enable_if and we failed to find the nested type
3720  // within enable_if in a SFINAE context, dig out the specific
3721  // enable_if condition that failed and present that instead.
3723  if (auto DeductionInfo = isSFINAEContext()) {
3724  if (*DeductionInfo &&
3725  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3726  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3727  diag::err_typename_nested_not_found_enable_if &&
3728  TemplateArgs[0].getArgument().getKind()
3730  Expr *FailedCond;
3731  std::string FailedDescription;
3732  std::tie(FailedCond, FailedDescription) =
3733  findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
3734 
3735  // Remove the old SFINAE diagnostic.
3736  PartialDiagnosticAt OldDiag =
3738  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3739 
3740  // Add a new SFINAE diagnostic specifying which condition
3741  // failed.
3742  (*DeductionInfo)->addSFINAEDiagnostic(
3743  OldDiag.first,
3744  PDiag(diag::err_typename_nested_not_found_requirement)
3745  << FailedDescription
3746  << FailedCond->getSourceRange());
3747  }
3748  }
3749  }
3750 
3751  return QualType();
3752  }
3753  } else if (Name.isDependent() ||
3755  TemplateArgs, Converted)) {
3756  // This class template specialization is a dependent
3757  // type. Therefore, its canonical type is another class template
3758  // specialization type that contains all of the converted
3759  // arguments in canonical form. This ensures that, e.g., A<T> and
3760  // A<T, T> have identical types when A is declared as:
3761  //
3762  // template<typename T, typename U = T> struct A;
3763  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3764 
3765  // This might work out to be a current instantiation, in which
3766  // case the canonical type needs to be the InjectedClassNameType.
3767  //
3768  // TODO: in theory this could be a simple hashtable lookup; most
3769  // changes to CurContext don't change the set of current
3770  // instantiations.
3771  if (isa<ClassTemplateDecl>(Template)) {
3772  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3773  // If we get out to a namespace, we're done.
3774  if (Ctx->isFileContext()) break;
3775 
3776  // If this isn't a record, keep looking.
3777  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3778  if (!Record) continue;
3779 
3780  // Look for one of the two cases with InjectedClassNameTypes
3781  // and check whether it's the same template.
3782  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3783  !Record->getDescribedClassTemplate())
3784  continue;
3785 
3786  // Fetch the injected class name type and check whether its
3787  // injected type is equal to the type we just built.
3788  QualType ICNT = Context.getTypeDeclType(Record);
3789  QualType Injected = cast<InjectedClassNameType>(ICNT)
3790  ->getInjectedSpecializationType();
3791 
3792  if (CanonType != Injected->getCanonicalTypeInternal())
3793  continue;
3794 
3795  // If so, the canonical type of this TST is the injected
3796  // class name type of the record we just found.
3797  assert(ICNT.isCanonical());
3798  CanonType = ICNT;
3799  break;
3800  }
3801  }
3802  } else if (ClassTemplateDecl *ClassTemplate
3803  = dyn_cast<ClassTemplateDecl>(Template)) {
3804  // Find the class template specialization declaration that
3805  // corresponds to these arguments.
3806  void *InsertPos = nullptr;
3808  = ClassTemplate->findSpecialization(Converted, InsertPos);
3809  if (!Decl) {
3810  // This is the first time we have referenced this class template
3811  // specialization. Create the canonical declaration and add it to
3812  // the set of specializations.
3814  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3815  ClassTemplate->getDeclContext(),
3816  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3817  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3818  ClassTemplate->AddSpecialization(Decl, InsertPos);
3819  if (ClassTemplate->isOutOfLine())
3820  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3821  }
3822 
3823  if (Decl->getSpecializationKind() == TSK_Undeclared &&
3824  ClassTemplate->getTemplatedDecl()->hasAttrs()) {
3825  InstantiatingTemplate Inst(*this, TemplateLoc, Decl);
3826  if (!Inst.isInvalid()) {
3827  MultiLevelTemplateArgumentList TemplateArgLists;
3828  TemplateArgLists.addOuterTemplateArguments(Converted);
3829  InstantiateAttrsForDecl(TemplateArgLists,
3830  ClassTemplate->getTemplatedDecl(), Decl);
3831  }
3832  }
3833 
3834  // Diagnose uses of this specialization.
3835  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3836 
3837  CanonType = Context.getTypeDeclType(Decl);
3838  assert(isa<RecordType>(CanonType) &&
3839  "type of non-dependent specialization is not a RecordType");
3840  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3841  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3842  TemplateArgs);
3843  }
3844 
3845  // Build the fully-sugared type for this class template
3846  // specialization, which refers back to the class template
3847  // specialization we created or found.
3848  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3849 }
3850 
3852  TemplateNameKind &TNK,
3853  SourceLocation NameLoc,
3854  IdentifierInfo *&II) {
3855  assert(TNK == TNK_Undeclared_template && "not an undeclared template name");
3856 
3857  TemplateName Name = ParsedName.get();
3858  auto *ATN = Name.getAsAssumedTemplateName();
3859  assert(ATN && "not an assumed template name");
3860  II = ATN->getDeclName().getAsIdentifierInfo();
3861 
3862  if (!resolveAssumedTemplateNameAsType(S, Name, NameLoc, /*Diagnose*/false)) {
3863  // Resolved to a type template name.
3864  ParsedName = TemplateTy::make(Name);
3865  TNK = TNK_Type_template;
3866  }
3867 }
3868 
3870  SourceLocation NameLoc,
3871  bool Diagnose) {
3872  // We assumed this undeclared identifier to be an (ADL-only) function
3873  // template name, but it was used in a context where a type was required.
3874  // Try to typo-correct it now.
3875  AssumedTemplateStorage *ATN = Name.getAsAssumedTemplateName();
3876  assert(ATN && "not an assumed template name");
3877 
3878  LookupResult R(*this, ATN->getDeclName(), NameLoc, LookupOrdinaryName);
3879  struct CandidateCallback : CorrectionCandidateCallback {
3880  bool ValidateCandidate(const TypoCorrection &TC) override {
3881  return TC.getCorrectionDecl() &&
3883  }
3884  std::unique_ptr<CorrectionCandidateCallback> clone() override {
3885  return std::make_unique<CandidateCallback>(*this);
3886  }
3887  } FilterCCC;
3888 
3889  TypoCorrection Corrected =
3890  CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
3891  FilterCCC, CTK_ErrorRecovery);
3892  if (Corrected && Corrected.getFoundDecl()) {
3893  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest)
3894  << ATN->getDeclName());
3895  Name = TemplateName(Corrected.getCorrectionDeclAs<TemplateDecl>());
3896  return false;
3897  }
3898 
3899  if (Diagnose)
3900  Diag(R.getNameLoc(), diag::err_no_template) << R.getLookupName();
3901  return true;
3902 }
3903 
3905  Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
3906  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3907  SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
3908  ASTTemplateArgsPtr TemplateArgsIn, SourceLocation RAngleLoc,
3909  bool IsCtorOrDtorName, bool IsClassName) {
3910  if (SS.isInvalid())
3911  return true;
3912 
3913  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3914  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3915 
3916  // C++ [temp.res]p3:
3917  // A qualified-id that refers to a type and in which the
3918  // nested-name-specifier depends on a template-parameter (14.6.2)
3919  // shall be prefixed by the keyword typename to indicate that the
3920  // qualified-id denotes a type, forming an
3921  // elaborated-type-specifier (7.1.5.3).
3922  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3923  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3924  << SS.getScopeRep() << TemplateII->getName();
3925  // Recover as if 'typename' were specified.
3926  // FIXME: This is not quite correct recovery as we don't transform SS
3927  // into the corresponding dependent form (and we don't diagnose missing
3928  // 'template' keywords within SS as a result).
3929  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3930  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3931  TemplateArgsIn, RAngleLoc);
3932  }
3933 
3934  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3935  // it's not actually allowed to be used as a type in most cases. Because
3936  // we annotate it before we know whether it's valid, we have to check for
3937  // this case here.
3938  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3939  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3940  Diag(TemplateIILoc,
3941  TemplateKWLoc.isInvalid()
3942  ? diag::err_out_of_line_qualified_id_type_names_constructor
3943  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3944  << TemplateII << 0 /*injected-class-name used as template name*/
3945  << 1 /*if any keyword was present, it was 'template'*/;
3946  }
3947  }
3948 
3949  TemplateName Template = TemplateD.get();
3950  if (Template.getAsAssumedTemplateName() &&
3951  resolveAssumedTemplateNameAsType(S, Template, TemplateIILoc))
3952  return true;
3953 
3954  // Translate the parser's template argument list in our AST format.
3955  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3956  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3957 
3958  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3959  QualType T
3961  DTN->getQualifier(),
3962  DTN->getIdentifier(),
3963  TemplateArgs);
3964  // Build type-source information.
3965  TypeLocBuilder TLB;
3969  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3970  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3971  SpecTL.setTemplateNameLoc(TemplateIILoc);
3972  SpecTL.setLAngleLoc(LAngleLoc);
3973  SpecTL.setRAngleLoc(RAngleLoc);
3974  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3975  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3976  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3977  }
3978 
3979  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3980  if (Result.isNull())
3981  return true;
3982 
3983  // Build type-source information.
3984  TypeLocBuilder TLB;
3986  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3987  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3988  SpecTL.setTemplateNameLoc(TemplateIILoc);
3989  SpecTL.setLAngleLoc(LAngleLoc);
3990  SpecTL.setRAngleLoc(RAngleLoc);
3991  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3992  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3993 
3994  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3995  // constructor or destructor name (in such a case, the scope specifier
3996  // will be attached to the enclosing Decl or Expr node).
3997  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3998  // Create an elaborated-type-specifier containing the nested-name-specifier.
3999  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
4000  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
4002  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
4003  }
4004 
4005  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
4006 }
4007 
4009  TypeSpecifierType TagSpec,
4010  SourceLocation TagLoc,
4011  CXXScopeSpec &SS,
4012  SourceLocation TemplateKWLoc,
4013  TemplateTy TemplateD,
4014  SourceLocation TemplateLoc,
4015  SourceLocation LAngleLoc,
4016  ASTTemplateArgsPtr TemplateArgsIn,
4017  SourceLocation RAngleLoc) {
4018  if (SS.isInvalid())
4019  return TypeResult(true);
4020 
4021  TemplateName Template = TemplateD.get();
4022 
4023  // Translate the parser's template argument list in our AST format.
4024  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
4025  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
4026 
4027  // Determine the tag kind
4029  ElaboratedTypeKeyword Keyword
4031 
4032  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
4034  DTN->getQualifier(),
4035  DTN->getIdentifier(),
4036  TemplateArgs);
4037 
4038  // Build type-source information.
4039  TypeLocBuilder TLB;
4042  SpecTL.setElaboratedKeywordLoc(TagLoc);
4043  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
4044  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4045  SpecTL.setTemplateNameLoc(TemplateLoc);
4046  SpecTL.setLAngleLoc(LAngleLoc);
4047  SpecTL.setRAngleLoc(RAngleLoc);
4048  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
4049  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
4050  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
4051  }
4052 
4053  if (TypeAliasTemplateDecl *TAT =
4054  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
4055  // C++0x [dcl.type.elab]p2:
4056  // If the identifier resolves to a typedef-name or the simple-template-id
4057  // resolves to an alias template specialization, the
4058  // elaborated-type-specifier is ill-formed.
4059  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
4060  << TAT << NTK_TypeAliasTemplate << TagKind;
4061  Diag(TAT->getLocation(), diag::note_declared_at);
4062  }
4063 
4064  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
4065  if (Result.isNull())
4066  return TypeResult(true);
4067 
4068  // Check the tag kind
4069  if (const RecordType *RT = Result->getAs<RecordType>()) {
4070  RecordDecl *D = RT->getDecl();
4071 
4073  assert(Id && "templated class must have an identifier");
4074 
4075  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
4076  TagLoc, Id)) {
4077  Diag(TagLoc, diag::err_use_with_wrong_tag)
4078  << Result
4080  Diag(D->getLocation(), diag::note_previous_use);
4081  }
4082  }
4083 
4084  // Provide source-location information for the template specialization.
4085  TypeLocBuilder TLB;
4087  = TLB.push<TemplateSpecializationTypeLoc>(Result);
4088  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4089  SpecTL.setTemplateNameLoc(TemplateLoc);
4090  SpecTL.setLAngleLoc(LAngleLoc);
4091  SpecTL.setRAngleLoc(RAngleLoc);
4092  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
4093  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
4094 
4095  // Construct an elaborated type containing the nested-name-specifier (if any)
4096  // and tag keyword.
4097  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
4098  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
4099  ElabTL.setElaboratedKeywordLoc(TagLoc);
4100  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
4101  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
4102 }
4103 
4104 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
4105  NamedDecl *PrevDecl,
4106  SourceLocation Loc,
4108 
4110 
4112  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
4113  switch (Arg.getKind()) {
4120  return false;
4121 
4122  case TemplateArgument::Type: {
4123  QualType Type = Arg.getAsType();
4124  const TemplateTypeParmType *TPT =
4126  return TPT && !Type.hasQualifiers() &&
4127  TPT->getDepth() == Depth && TPT->getIndex() == Index;
4128  }
4129 
4131  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
4132  if (!DRE || !DRE->getDecl())
4133  return false;
4134  const NonTypeTemplateParmDecl *NTTP =
4135  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4136  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
4137  }
4138 
4140  const TemplateTemplateParmDecl *TTP =
4141  dyn_cast_or_null<TemplateTemplateParmDecl>(
4143  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
4144  }
4145  llvm_unreachable("unexpected kind of template argument");
4146 }
4147 
4150  if (Params->size() != Args.size())
4151  return false;
4152 
4153  unsigned Depth = Params->getDepth();
4154 
4155  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
4156  TemplateArgument Arg = Args[I];
4157 
4158  // If the parameter is a pack expansion, the argument must be a pack
4159  // whose only element is a pack expansion.
4160  if (Params->getParam(I)->isParameterPack()) {
4161  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
4162  !Arg.pack_begin()->isPackExpansion())
4163  return false;
4164  Arg = Arg.pack_begin()->getPackExpansionPattern();
4165  }
4166 
4168  return false;
4169  }
4170 
4171  return true;
4172 }
4173 
4174 template<typename PartialSpecDecl>
4175 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
4176  if (Partial->getDeclContext()->isDependentContext())
4177  return;
4178 
4179  // FIXME: Get the TDK from deduction in order to provide better diagnostics
4180  // for non-substitution-failure issues?
4181  TemplateDeductionInfo Info(Partial->getLocation());
4182  if (S.isMoreSpecializedThanPrimary(Partial, Info))
4183  return;
4184 
4185  auto *Template = Partial->getSpecializedTemplate();
4186  S.Diag(Partial->getLocation(),
4187  diag::ext_partial_spec_not_more_specialized_than_primary)
4188  << isa<VarTemplateDecl>(Template);
4189 
4190  if (Info.hasSFINAEDiagnostic()) {
4193  Info.takeSFINAEDiagnostic(Diag);
4194  SmallString<128> SFINAEArgString;
4195  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
4196  S.Diag(Diag.first,
4197  diag::note_partial_spec_not_more_specialized_than_primary)
4198  << SFINAEArgString;
4199  }
4200 
4201  S.Diag(Template->getLocation(), diag::note_template_decl_here);
4202  SmallVector<const Expr *, 3> PartialAC, TemplateAC;
4203  Template->getAssociatedConstraints(TemplateAC);
4204  Partial->getAssociatedConstraints(PartialAC);
4205  S.MaybeEmitAmbiguousAtomicConstraintsDiagnostic(Partial, PartialAC, Template,
4206  TemplateAC);
4207 }
4208 
4209 static void
4211  const llvm::SmallBitVector &DeducibleParams) {
4212  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
4213  if (!DeducibleParams[I]) {
4214  NamedDecl *Param = TemplateParams->getParam(I);
4215  if (Param->getDeclName())
4216  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4217  << Param->getDeclName();
4218  else
4219  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4220  << "(anonymous)";
4221  }
4222  }
4223 }
4224 
4225 
4226 template<typename PartialSpecDecl>
4228  PartialSpecDecl *Partial) {
4229  // C++1z [temp.class.spec]p8: (DR1495)
4230  // - The specialization shall be more specialized than the primary
4231  // template (14.5.5.2).
4232  checkMoreSpecializedThanPrimary(S, Partial);
4233 
4234  // C++ [temp.class.spec]p8: (DR1315)
4235  // - Each template-parameter shall appear at least once in the
4236  // template-id outside a non-deduced context.
4237  // C++1z [temp.class.spec.match]p3 (P0127R2)
4238  // If the template arguments of a partial specialization cannot be
4239  // deduced because of the structure of its template-parameter-list
4240  // and the template-id, the program is ill-formed.
4241  auto *TemplateParams = Partial->getTemplateParameters();
4242  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4243  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
4244  TemplateParams->getDepth(), DeducibleParams);
4245 
4246  if (!DeducibleParams.all()) {
4247  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4248  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
4249  << isa<VarTemplatePartialSpecializationDecl>(Partial)
4250  << (NumNonDeducible > 1)
4251  << SourceRange(Partial->getLocation(),
4252  Partial->getTemplateArgsAsWritten()->RAngleLoc);
4253  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
4254  }
4255 }
4256 
4259  checkTemplatePartialSpecialization(*this, Partial);
4260 }
4261 
4264  checkTemplatePartialSpecialization(*this, Partial);
4265 }
4266 
4268  // C++1z [temp.param]p11:
4269  // A template parameter of a deduction guide template that does not have a
4270  // default-argument shall be deducible from the parameter-type-list of the
4271  // deduction guide template.
4272  auto *TemplateParams = TD->getTemplateParameters();
4273  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4274  MarkDeducedTemplateParameters(TD, DeducibleParams);
4275  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
4276  // A parameter pack is deducible (to an empty pack).
4277  auto *Param = TemplateParams->getParam(I);
4278  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
4279  DeducibleParams[I] = true;
4280  }
4281 
4282  if (!DeducibleParams.all()) {
4283  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4284  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
4285  << (NumNonDeducible > 1);
4286  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
4287  }
4288 }
4289 
4291  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
4292  TemplateParameterList *TemplateParams, StorageClass SC,
4293  bool IsPartialSpecialization) {
4294  // D must be variable template id.
4296  "Variable template specialization is declared with a template it.");
4297 
4298  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
4299  TemplateArgumentListInfo TemplateArgs =
4300  makeTemplateArgumentListInfo(*this, *TemplateId);
4301  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
4302  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
4303  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
4304 
4305  TemplateName Name = TemplateId->Template.get();
4306 
4307  // The template-id must name a variable template.
4308  VarTemplateDecl *VarTemplate =
4309  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
4310  if (!VarTemplate) {
4311  NamedDecl *FnTemplate;
4312  if (auto *OTS = Name.getAsOverloadedTemplate())
4313  FnTemplate = *OTS->begin();
4314  else
4315  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
4316  if (FnTemplate)
4317  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
4318  << FnTemplate->getDeclName();
4319  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
4321  }
4322 
4323  // Check for unexpanded parameter packs in any of the template arguments.
4324  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
4325  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
4326  UPPC_PartialSpecialization))
4327  return true;
4328 
4329  // Check that the template argument list is well-formed for this
4330  // template.
4332  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
4333  false, Converted,
4334  /*UpdateArgsWithConversion=*/true))
4335  return true;
4336 
4337  // Find the variable template (partial) specialization declaration that
4338  // corresponds to these arguments.
4340  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
4341  TemplateArgs.size(), Converted))
4342  return true;
4343 
4344  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
4345  // also do them during instantiation.
4346  if (!Name.isDependent() &&
4348  Converted)) {
4349  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
4350  << VarTemplate->getDeclName();
4351  IsPartialSpecialization = false;
4352  }
4353 
4355  Converted) &&
4356  (!Context.getLangOpts().CPlusPlus20 ||
4357  !TemplateParams->hasAssociatedConstraints())) {
4358  // C++ [temp.class.spec]p9b3:
4359  //
4360  // -- The argument list of the specialization shall not be identical
4361  // to the implicit argument list of the primary template.
4362  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
4363  << /*variable template*/ 1
4364  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
4365  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
4366  // FIXME: Recover from this by treating the declaration as a redeclaration
4367  // of the primary template.
4368  return true;
4369  }
4370  }
4371 
4372  void *InsertPos = nullptr;
4373  VarTemplateSpecializationDecl *PrevDecl = nullptr;
4374 
4376  PrevDecl = VarTemplate->findPartialSpecialization(Converted, TemplateParams,
4377  InsertPos);
4378  else
4379  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
4380 
4382 
4383  // Check whether we can declare a variable template specialization in
4384  // the current scope.
4385  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
4386  TemplateNameLoc,
4388  return true;
4389 
4390  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
4391  // Since the only prior variable template specialization with these
4392  // arguments was referenced but not declared, reuse that
4393  // declaration node as our own, updating its source location and
4394  // the list of outer template parameters to reflect our new declaration.
4395  Specialization = PrevDecl;
4396  Specialization->setLocation(TemplateNameLoc);
4397  PrevDecl = nullptr;
4398  } else if (IsPartialSpecialization) {
4399  // Create a new class template partial specialization declaration node.
4401  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
4404  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
4405  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
4406  Converted, TemplateArgs);
4407 
4408  if (!PrevPartial)
4409  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
4410  Specialization = Partial;
4411 
4412  // If we are providing an explicit specialization of a member variable
4413  // template specialization, make a note of that.
4414  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
4415  PrevPartial->setMemberSpecialization();
4416 
4417  CheckTemplatePartialSpecialization(Partial);
4418  } else {
4419  // Create a new class template specialization declaration node for
4420  // this explicit specialization or friend declaration.
4422  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
4423  VarTemplate, DI->getType(), DI, SC, Converted);
4424  Specialization->setTemplateArgsInfo(TemplateArgs);
4425 
4426  if (!PrevDecl)
4427  VarTemplate->AddSpecialization(Specialization, InsertPos);
4428  }
4429 
4430  // C++ [temp.expl.spec]p6:
4431  // If a template, a member template or the member of a class template is
4432  // explicitly specialized then that specialization shall be declared
4433  // before the first use of that specialization that would cause an implicit
4434  // instantiation to take place, in every translation unit in which such a
4435  // use occurs; no diagnostic is required.
4436  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
4437  bool Okay = false;
4438  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
4439  // Is there any previous explicit specialization declaration?
4441  Okay = true;
4442  break;
4443  }
4444  }
4445 
4446  if (!Okay) {
4447  SourceRange Range(TemplateNameLoc, RAngleLoc);
4448  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
4449  << Name << Range;
4450 
4451  Diag(PrevDecl->getPointOfInstantiation(),
4452  diag::note_instantiation_required_here)
4453  << (PrevDecl->getTemplateSpecializationKind() !=
4455  return true;
4456  }
4457  }
4458 
4459  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
4460  Specialization->setLexicalDeclContext(CurContext);
4461 
4462  // Add the specialization into its lexical context, so that it can
4463  // be seen when iterating through the list of declarations in that
4464  // context. However, specializations are not found by name lookup.
4465  CurContext->addDecl(Specialization);
4466 
4467  // Note that this is an explicit specialization.
4468  Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
4469 
4470  if (PrevDecl) {
4471  // Check that this isn't a redefinition of this specialization,
4472  // merging with previous declarations.
4473  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
4474  forRedeclarationInCurContext());
4475  PrevSpec.addDecl(PrevDecl);
4476  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
4477  } else if (Specialization->isStaticDataMember() &&
4478  Specialization->isOutOfLine()) {
4479  Specialization->setAccess(VarTemplate->getAccess());
4480  }
4481 
4482  return Specialization;
4483 }
4484 
4485 namespace {
4486 /// A partial specialization whose template arguments have matched
4487 /// a given template-id.
4488 struct PartialSpecMatchResult {
4490  TemplateArgumentList *Args;
4491 };
4492 } // end anonymous namespace
4493 
4494 DeclResult
4496  SourceLocation TemplateNameLoc,
4497  const TemplateArgumentListInfo &TemplateArgs) {
4498  assert(Template && "A variable template id without template?");
4499 
4500  // Check that the template argument list is well-formed for this template.
4502  if (CheckTemplateArgumentList(
4503  Template, TemplateNameLoc,
4504  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
4505  Converted, /*UpdateArgsWithConversion=*/true))
4506  return true;
4507 
4508  // Produce a placeholder value if the specialization is dependent.
4509  if (Template->getDeclContext()->isDependentContext() ||
4511  Converted))
4512  return DeclResult();
4513 
4514  // Find the variable template specialization declaration that
4515  // corresponds to these arguments.
4516  void *InsertPos = nullptr;
4517  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
4518  Converted, InsertPos)) {
4519  checkSpecializationVisibility(TemplateNameLoc, Spec);
4520  // If we already have a variable template specialization, return it.
4521  return Spec;
4522  }
4523 
4524  // This is the first time we have referenced this variable template
4525  // specialization. Create the canonical declaration and add it to
4526  // the set of specializations, based on the closest partial specialization
4527  // that it represents. That is,
4528  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
4530  Converted);
4531  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
4532  bool AmbiguousPartialSpec = false;
4533  typedef PartialSpecMatchResult MatchResult;
4535  SourceLocation PointOfInstantiation = TemplateNameLoc;
4536  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
4537  /*ForTakingAddress=*/false);
4538 
4539  // 1. Attempt to find the closest partial specialization that this
4540  // specializes, if any.
4541  // TODO: Unify with InstantiateClassTemplateSpecialization()?
4542  // Perhaps better after unification of DeduceTemplateArguments() and
4543  // getMoreSpecializedPartialSpecialization().
4545  Template->getPartialSpecializations(PartialSpecs);
4546 
4547  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
4548  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
4549  TemplateDeductionInfo Info(FailedCandidates.getLocation());
4550 
4551  if (TemplateDeductionResult Result =
4552  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
4553  // Store the failed-deduction information for use in diagnostics, later.
4554  // TODO: Actually use the failed-deduction info?
4555  FailedCandidates.addCandidate().set(
4556  DeclAccessPair::make(Template, AS_public), Partial,
4557  MakeDeductionFailureInfo(Context, Result, Info));
4558  (void)Result;
4559  } else {
4560  Matched.push_back(PartialSpecMatchResult());
4561  Matched.back().Partial = Partial;
4562  Matched.back().Args = Info.take();
4563  }
4564  }
4565 
4566  if (Matched.size() >= 1) {
4567  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
4568  if (Matched.size() == 1) {
4569  // -- If exactly one matching specialization is found, the
4570  // instantiation is generated from that specialization.
4571  // We don't need to do anything for this.
4572  } else {
4573  // -- If more than one matching specialization is found, the
4574  // partial order rules (14.5.4.2) are used to determine
4575  // whether one of the specializations is more specialized
4576  // than the others. If none of the specializations is more
4577  // specialized than all of the other matching
4578  // specializations, then the use of the variable template is
4579  // ambiguous and the program is ill-formed.
4580  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4581  PEnd = Matched.end();
4582  P != PEnd; ++P) {
4583  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4584  PointOfInstantiation) ==
4585  P->Partial)
4586  Best = P;
4587  }
4588 
4589  // Determine if the best partial specialization is more specialized than
4590  // the others.
4591  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4592  PEnd = Matched.end();
4593  P != PEnd; ++P) {
4594  if (P != Best && getMoreSpecializedPartialSpecialization(
4595  P->Partial, Best->Partial,
4596  PointOfInstantiation) != Best->Partial) {
4597  AmbiguousPartialSpec = true;
4598  break;
4599  }
4600  }
4601  }
4602 
4603  // Instantiate using the best variable template partial specialization.
4604  InstantiationPattern = Best->Partial;
4605  InstantiationArgs = Best->Args;
4606  } else {
4607  // -- If no match is found, the instantiation is generated
4608  // from the primary template.
4609  // InstantiationPattern = Template->getTemplatedDecl();
4610  }
4611 
4612  // 2. Create the canonical declaration.
4613  // Note that we do not instantiate a definition until we see an odr-use
4614  // in DoMarkVarDeclReferenced().
4615  // FIXME: LateAttrs et al.?
4616  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4617  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4618  Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
4619  if (!Decl)
4620  return true;
4621 
4622  if (AmbiguousPartialSpec) {
4623  // Partial ordering did not produce a clear winner. Complain.
4624  Decl->setInvalidDecl();
4625  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4626  << Decl;
4627 
4628  // Print the matching partial specializations.
4629  for (MatchResult P : Matched)
4630  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4631  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4632  *P.Args);
4633  return true;
4634  }
4635 
4637  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4638  Decl->setInstantiationOf(D, InstantiationArgs);
4639 
4640  checkSpecializationVisibility(TemplateNameLoc, Decl);
4641 
4642  assert(Decl && "No variable template specialization?");
4643  return Decl;
4644 }
4645 
4646 ExprResult
4648  const DeclarationNameInfo &NameInfo,
4649  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4650  const TemplateArgumentListInfo *TemplateArgs) {
4651 
4652  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4653  *TemplateArgs);
4654  if (Decl.isInvalid())
4655  return ExprError();
4656 
4657  if (!Decl.get())
4658  return ExprResult();
4659 
4660  VarDecl *Var = cast<VarDecl>(Decl.get());
4661  if (!Var->getTemplateSpecializationKind())
4663  NameInfo.getLoc());
4664 
4665  // Build an ordinary singleton decl ref.
4666  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4667  /*FoundD=*/nullptr, TemplateArgs);
4668 }
4669 
4671  SourceLocation Loc) {
4672  Diag(Loc, diag::err_template_missing_args)
4673  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4674  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4675  Diag(TD->getLocation(), diag::note_template_decl_here)
4676  << TD->getTemplateParameters()->getSourceRange();
4677  }
4678 }
4679 
4680 ExprResult
4682  SourceLocation TemplateKWLoc,
4683  const DeclarationNameInfo &ConceptNameInfo,
4684  NamedDecl *FoundDecl,
4685  ConceptDecl *NamedConcept,
4686  const TemplateArgumentListInfo *TemplateArgs) {
4687  assert(NamedConcept && "A concept template id without a template?");
4688 
4690  if (CheckTemplateArgumentList(NamedConcept, ConceptNameInfo.getLoc(),
4691  const_cast<TemplateArgumentListInfo&>(*TemplateArgs),
4692  /*PartialTemplateArgs=*/false, Converted,
4693  /*UpdateArgsWithConversion=*/false))
4694  return ExprError();
4695 
4696  ConstraintSatisfaction Satisfaction;
4697  bool AreArgsDependent =
4699  Converted);
4700  if (!AreArgsDependent &&
4702  NamedConcept, {NamedConcept->getConstraintExpr()}, Converted,
4703  SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameInfo.getLoc(),
4704  TemplateArgs->getRAngleLoc()),
4705  Satisfaction))
4706  return ExprError();
4707 
4708  return ConceptSpecializationExpr::Create(Context,
4709  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
4710  TemplateKWLoc, ConceptNameInfo, FoundDecl, NamedConcept,
4711  ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
4712  AreArgsDependent ? nullptr : &Satisfaction);
4713 }
4714 
4716  SourceLocation TemplateKWLoc,
4717  LookupResult &R,
4718  bool RequiresADL,
4719  const TemplateArgumentListInfo *TemplateArgs) {
4720  // FIXME: Can we do any checking at this point? I guess we could check the
4721  // template arguments that we have against the template name, if the template
4722  // name refers to a single template. That's not a terribly common case,
4723  // though.
4724  // foo<int> could identify a single function unambiguously
4725  // This approach does NOT work, since f<int>(1);
4726  // gets resolved prior to resorting to overload resolution
4727  // i.e., template<class T> void f(double);
4728  // vs template<class T, class U> void f(U);
4729 
4730  // These should be filtered out by our callers.
4731  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4732 
4733  // Non-function templates require a template argument list.
4734  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4735  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4736  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4737  return ExprError();
4738  }
4739  }
4740 
4741  // In C++1y, check variable template ids.
4742  if (R.getAsSingle<VarTemplateDecl>()) {
4743  ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
4745  TemplateKWLoc, TemplateArgs);
4746  if (Res.isInvalid() || Res.isUsable())
4747  return Res;
4748  // Result is dependent. Carry on to build an UnresolvedLookupEpxr.
4749  }
4750 
4751  if (R.getAsSingle<ConceptDecl>()) {
4752  return CheckConceptTemplateId(SS, TemplateKWLoc, R.getLookupNameInfo(),
4753  R.getFoundDecl(),
4754  R.getAsSingle<ConceptDecl>(), TemplateArgs);
4755  }
4756 
4757  // We don't want lookup warnings at this point.
4758  R.suppressDiagnostics();
4759 
4762  SS.getWithLocInContext(Context),
4763  TemplateKWLoc,
4764  R.getLookupNameInfo(),
4765  RequiresADL, TemplateArgs,
4766  R.begin(), R.end());
4767 
4768  return ULE;
4769 }
4770 
4771 // We actually only call this from template instantiation.
4772 ExprResult
4774  SourceLocation TemplateKWLoc,
4775  const DeclarationNameInfo &NameInfo,
4776  const TemplateArgumentListInfo *TemplateArgs) {
4777 
4778  assert(TemplateArgs || TemplateKWLoc.isValid());
4779  DeclContext *DC;
4780  if (!(DC = computeDeclContext(SS, false)) ||
4781  DC->isDependentContext() ||
4782  RequireCompleteDeclContext(SS, DC))
4783  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4784 
4785  bool MemberOfUnknownSpecialization;
4786  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4787  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4788  /*Entering*/false, MemberOfUnknownSpecialization,
4789  TemplateKWLoc))
4790  return ExprError();
4791 
4792  if (R.isAmbiguous())
4793  return ExprError();
4794 
4795  if (R.empty()) {
4796  Diag(NameInfo.getLoc(), diag::err_no_member)
4797  << NameInfo.getName() << DC << SS.getRange();
4798  return ExprError();
4799  }
4800 
4801  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4802  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4803  << SS.getScopeRep()
4804  << NameInfo.getName().getAsString() << SS.getRange();
4805  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4806  return ExprError();
4807  }
4808 
4809  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4810 }
4811 
4812 /// Form a template name from a name that is syntactically required to name a
4813 /// template, either due to use of the 'template' keyword or because a name in
4814 /// this syntactic context is assumed to name a template (C++ [temp.names]p2-4).
4815 ///
4816 /// This action forms a template name given the name of the template and its
4817 /// optional scope specifier. This is used when the 'template' keyword is used
4818 /// or when the parsing context unambiguously treats a following '<' as
4819 /// introducing a template argument list. Note that this may produce a
4820 /// non-dependent template name if we can perform the lookup now and identify
4821 /// the named template.
4822 ///
4823 /// For example, given "x.MetaFun::template apply", the scope specifier
4824 /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
4825 /// of the "template" keyword, and "apply" is the \p Name.
4827  CXXScopeSpec &SS,
4828  SourceLocation TemplateKWLoc,
4829  const UnqualifiedId &Name,
4830  ParsedType ObjectType,
4831  bool EnteringContext,
4832  TemplateTy &Result,
4833  bool AllowInjectedClassName) {
4834  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4835  Diag(TemplateKWLoc,
4836  getLangOpts().CPlusPlus11 ?
4837  diag::warn_cxx98_compat_template_outside_of_template :
4838  diag::ext_template_outside_of_template)
4839  << FixItHint::CreateRemoval(TemplateKWLoc);
4840 
4841  if (SS.isInvalid())
4842  return TNK_Non_template;
4843 
4844  // Figure out where isTemplateName is going to look.
4845  DeclContext *LookupCtx = nullptr;
4846  if (SS.isNotEmpty())
4847  LookupCtx = computeDeclContext(SS, EnteringContext);
4848  else if (ObjectType)
4849  LookupCtx = computeDeclContext(GetTypeFromParser(ObjectType));
4850 
4851  // C++0x [temp.names]p5:
4852  // If a name prefixed by the keyword template is not the name of
4853  // a template, the program is ill-formed. [Note: the keyword
4854  // template may not be applied to non-template members of class
4855  // templates. -end note ] [ Note: as is the case with the
4856  // typename prefix, the template prefix is allowed in cases
4857  // where it is not strictly necessary; i.e., when the
4858  // nested-name-specifier or the expression on the left of the ->
4859  // or . is not dependent on a template-parameter, or the use
4860  // does not appear in the scope of a template. -end note]
4861  //
4862  // Note: C++03 was more strict here, because it banned the use of
4863  // the "template" keyword prior to a template-name that was not a
4864  // dependent name. C++ DR468 relaxed this requirement (the
4865  // "template" keyword is now permitted). We follow the C++0x
4866  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4867  bool MemberOfUnknownSpecialization;
4868  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4869  ObjectType, EnteringContext, Result,
4870  MemberOfUnknownSpecialization);
4871  if (TNK != TNK_Non_template) {
4872  // We resolved this to a (non-dependent) template name. Return it.
4873  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
4874  if (!AllowInjectedClassName && SS.isNotEmpty() && LookupRD &&
4875  Name.getKind() == UnqualifiedIdKind::IK_Identifier &&
4876  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4877  // C++14 [class.qual]p2:
4878  // In a lookup in which function names are not ignored and the
4879  // nested-name-specifier nominates a class C, if the name specified
4880  // [...] is the injected-class-name of C, [...] the name is instead
4881  // considered to name the constructor
4882  //
4883  // We don't get here if naming the constructor would be valid, so we
4884  // just reject immediately and recover by treating the
4885  // injected-class-name as naming the template.
4886  Diag(Name.getBeginLoc(),
4887  diag::ext_out_of_line_qualified_id_type_names_constructor)
4888  << Name.Identifier
4889  << 0 /*injected-class-name used as template name*/
4890  << TemplateKWLoc.isValid();
4891  }
4892  return TNK;
4893  }
4894 
4895  if (!MemberOfUnknownSpecialization) {
4896  // Didn't find a template name, and the lookup wasn't dependent.
4897  // Do the lookup again to determine if this is a "nothing found" case or
4898  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4899  // need to do this.
4900  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4901  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4902  LookupOrdinaryName);
4903  bool MOUS;
4904  // Tell LookupTemplateName that we require a template so that it diagnoses
4905  // cases where it finds a non-template.
4906  RequiredTemplateKind RTK = TemplateKWLoc.isValid()
4907  ? RequiredTemplateKind(TemplateKWLoc)
4908  : TemplateNameIsRequired;
4909  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext, MOUS,
4910  RTK, nullptr, /*AllowTypoCorrection=*/false) &&
4911  !R.isAmbiguous()) {
4912  if (LookupCtx)
4913  Diag(Name.getBeginLoc(), diag::err_no_member)
4914  << DNI.getName() << LookupCtx << SS.getRange();
4915  else
4916  Diag(Name.getBeginLoc(), diag::err_undeclared_use)
4917  << DNI.getName() << SS.getRange();
4918  }
4919  return TNK_Non_template;
4920  }
4921 
4922  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4923 
4924  switch (Name.getKind()) {
4926  Result = TemplateTy::make(
4927  Context.getDependentTemplateName(Qualifier, Name.Identifier));
4929 
4931  Result = TemplateTy::make(Context.getDependentTemplateName(
4932  Qualifier, Name.OperatorFunctionId.Operator));
4933  return TNK_Function_template;
4934 
4936  // This is a kind of template name, but can never occur in a dependent
4937  // scope (literal operators can only be declared at namespace scope).
4938  break;
4939 
4940  default:
4941  break;
4942  }
4943 
4944  // This name cannot possibly name a dependent template. Diagnose this now
4945  // rather than building a dependent template name that can never be valid.
4946  Diag(Name.getBeginLoc(),
4947  diag::err_template_kw_refers_to_dependent_non_template)
4948  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4949  << TemplateKWLoc.isValid() << TemplateKWLoc;
4950  return TNK_Non_template;
4951 }
4952 
4954  TemplateArgumentLoc &AL,
4955  SmallVectorImpl<TemplateArgument> &Converted) {
4956  const TemplateArgument &Arg = AL.getArgument();
4957  QualType ArgType;
4958  TypeSourceInfo *TSI = nullptr;
4959 
4960  // Check template type parameter.
4961  switch(Arg.getKind()) {
4963  // C++ [temp.arg.type]p1:
4964  // A template-argument for a template-parameter which is a
4965  // type shall be a type-id.
4966  ArgType = Arg.getAsType();
4967  TSI = AL.getTypeSourceInfo();
4968  break;
4971  // We have a template type parameter but the template argument
4972  // is a template without any arguments.
4973  SourceRange SR = AL.getSourceRange();
4975  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4976  return true;
4977  }
4979  // We have a template type parameter but the template argument is an
4980  // expression; see if maybe it is missing the "typename" keyword.
4981  CXXScopeSpec SS;
4982  DeclarationNameInfo NameInfo;
4983 
4984  if (DependentScopeDeclRefExpr *ArgExpr =
4985  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4986  SS.Adopt(ArgExpr->getQualifierLoc());
4987  NameInfo = ArgExpr->getNameInfo();
4988  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4989  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4990  if (ArgExpr->isImplicitAccess()) {
4991  SS.Adopt(ArgExpr->getQualifierLoc());
4992  NameInfo = ArgExpr->getMemberNameInfo();
4993  }
4994  }
4995 
4996  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4997  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4998  LookupParsedName(Result, CurScope, &SS);
4999 
5000  if (Result.getAsSingle<TypeDecl>() ||
5001  Result.getResultKind() ==
5003  assert(SS.getScopeRep() && "dependent scope expr must has a scope!");
5004  // Suggest that the user add 'typename' before the NNS.
5005  SourceLocation Loc = AL.getSourceRange().getBegin();
5006  Diag(Loc, getLangOpts().MSVCCompat
5007  ? diag::ext_ms_template_type_arg_missing_typename
5008  : diag::err_template_arg_must_be_type_suggest)
5009  << FixItHint::CreateInsertion(Loc, "typename ");
5010  Diag(Param->getLocation(), diag::note_template_param_here);
5011 
5012  // Recover by synthesizing a type using the location information that we
5013  // already have.
5014  ArgType =
5015  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
5016  TypeLocBuilder TLB;
5017  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
5018  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
5019  TL.setQualifierLoc(SS.getWithLocInContext(Context));
5020  TL.setNameLoc(NameInfo.getLoc());
5021  TSI = TLB.getTypeSourceInfo(Context, ArgType);
5022 
5023  // Overwrite our input TemplateArgumentLoc so that we can recover
5024  // properly.
5025  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
5027 
5028  break;
5029  }
5030  }
5031  // fallthrough
5032  LLVM_FALLTHROUGH;
5033  }
5034  default: {
5035  // We have a template type parameter but the template argument
5036  // is not a type.
5037  SourceRange SR = AL.getSourceRange();
5038  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
5039  Diag(Param->getLocation(), diag::note_template_param_here);
5040 
5041  return true;
5042  }
5043  }
5044 
5045  if (CheckTemplateArgument(Param, TSI))
5046  return true;
5047 
5048  // Add the converted template type argument.
5049  ArgType = Context.getCanonicalType(ArgType);
5050 
5051  // Objective-C ARC:
5052  // If an explicitly-specified template argument type is a lifetime type
5053  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
5054  if (getLangOpts().ObjCAutoRefCount &&
5055  ArgType->isObjCLifetimeType() &&
5056  !ArgType.getObjCLifetime()) {
5057  Qualifiers Qs;
5059  ArgType = Context.getQualifiedType(ArgType, Qs);
5060  }
5061 
5062  Converted.push_back(TemplateArgument(ArgType));
5063  return false;
5064 }
5065 
5066 /// Substitute template arguments into the default template argument for
5067 /// the given template type parameter.
5068 ///
5069 /// \param SemaRef the semantic analysis object for which we are performing
5070 /// the substitution.
5071 ///
5072 /// \param Template the template that we are synthesizing template arguments
5073 /// for.
5074 ///
5075 /// \param TemplateLoc the location of the template name that started the
5076 /// template-id we are checking.
5077 ///
5078 /// \param RAngleLoc the location of the right angle bracket ('>') that
5079 /// terminates the template-id.
5080 ///
5081 /// \param Param the template template parameter whose default we are
5082 /// substituting into.
5083 ///
5084 /// \param Converted the list of template arguments provided for template
5085 /// parameters that precede \p Param in the template parameter list.
5086 /// \returns the substituted template argument, or NULL if an error occurred.
5087 static TypeSourceInfo *
5089  TemplateDecl *Template,
5090  SourceLocation TemplateLoc,
5091  SourceLocation RAngleLoc,
5092  TemplateTypeParmDecl *Param,
5093  SmallVectorImpl<TemplateArgument> &Converted) {
5094  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
5095 
5096  // If the argument type is dependent, instantiate it now based
5097  // on the previously-computed template arguments.
5098  if (ArgType->getType()->isInstantiationDependentType()) {
5099  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5100  Param, Template, Converted,
5101  SourceRange(TemplateLoc, RAngleLoc));
5102  if (Inst.isInvalid())
5103  return nullptr;
5104 
5105  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5106 
5107  // Only substitute for the innermost template argument list.
5108  MultiLevelTemplateArgumentList TemplateArgLists;
5109  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5110  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5111  TemplateArgLists.addOuterTemplateArguments(None);
5112 
5113  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5114  ArgType =
5115  SemaRef.SubstType(ArgType, TemplateArgLists,
5116  Param->getDefaultArgumentLoc(), Param->getDeclName());
5117  }
5118 
5119  return ArgType;
5120 }
5121 
5122 /// Substitute template arguments into the default template argument for
5123 /// the given non-type template parameter.
5124 ///
5125 /// \param SemaRef the semantic analysis object for which we are performing
5126 /// the substitution.
5127 ///
5128 /// \param Template the template that we are synthesizing template arguments
5129 /// for.
5130 ///
5131 /// \param TemplateLoc the location of the template name that started the
5132 /// template-id we are checking.
5133 ///
5134 /// \param RAngleLoc the location of the right angle bracket ('>') that
5135 /// terminates the template-id.
5136 ///
5137 /// \param Param the non-type template parameter whose default we are
5138 /// substituting into.
5139 ///
5140 /// \param Converted the list of template arguments provided for template
5141 /// parameters that precede \p Param in the template parameter list.
5142 ///
5143 /// \returns the substituted template argument, or NULL if an error occurred.
5144 static ExprResult
5146  TemplateDecl *Template,
5147  SourceLocation TemplateLoc,
5148  SourceLocation RAngleLoc,
5149  NonTypeTemplateParmDecl *Param,
5150  SmallVectorImpl<TemplateArgument> &Converted) {
5151  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5152  Param, Template, Converted,
5153  SourceRange(TemplateLoc, RAngleLoc));
5154  if (Inst.isInvalid())
5155  return ExprError();
5156 
5157  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5158 
5159  // Only substitute for the innermost template argument list.
5160  MultiLevelTemplateArgumentList TemplateArgLists;
5161  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5162  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5163  TemplateArgLists.addOuterTemplateArguments(None);
5164 
5165  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5166  EnterExpressionEvaluationContext ConstantEvaluated(
5168  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
5169 }
5170 
5171 /// Substitute template arguments into the default template argument for
5172 /// the given template template parameter.
5173 ///
5174 /// \param SemaRef the semantic analysis object for which we are performing
5175 /// the substitution.
5176 ///
5177 /// \param Template the template that we are synthesizing template arguments
5178 /// for.
5179 ///
5180 /// \param TemplateLoc the location of the template name that started the
5181 /// template-id we are checking.
5182 ///
5183 /// \param RAngleLoc the location of the right angle bracket ('>') that
5184 /// terminates the template-id.
5185 ///
5186 /// \param Param the template template parameter whose default we are
5187 /// substituting into.
5188 ///
5189 /// \param Converted the list of template arguments provided for template
5190 /// parameters that precede \p Param in the template parameter list.
5191 ///
5192 /// \param QualifierLoc Will be set to the nested-name-specifier (with
5193 /// source-location information) that precedes the template name.
5194 ///
5195 /// \returns the substituted template argument, or NULL if an error occurred.
5196 static TemplateName
5198  TemplateDecl *Template,
5199  SourceLocation TemplateLoc,
5200  SourceLocation RAngleLoc,
5201  TemplateTemplateParmDecl *Param,
5203  NestedNameSpecifierLoc &QualifierLoc) {
5205  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
5206  SourceRange(TemplateLoc, RAngleLoc));
5207  if (Inst.isInvalid())
5208  return TemplateName();
5209 
5210  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5211 
5212  // Only substitute for the innermost template argument list.
5213  MultiLevelTemplateArgumentList TemplateArgLists;
5214  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5215  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5216  TemplateArgLists.addOuterTemplateArguments(None);
5217 
5218  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5219  // Substitute into the nested-name-specifier first,
5220  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
5221  if (QualifierLoc) {
5222  QualifierLoc =
5223  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
5224  if (!QualifierLoc)
5225  return TemplateName();
5226  }
5227 
5228  return SemaRef.SubstTemplateName(
5229  QualifierLoc,
5232  TemplateArgLists);
5233 }
5234 
5235 /// If the given template parameter has a default template
5236 /// argument, substitute into that default template argument and
5237 /// return the corresponding template argument.
5240  SourceLocation TemplateLoc,
5241  SourceLocation RAngleLoc,
5242  Decl *Param,
5244  &Converted,
5245  bool &HasDefaultArg) {
5246  HasDefaultArg = false;
5247 
5248  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
5249  if (!hasVisibleDefaultArgument(TypeParm))
5250  return TemplateArgumentLoc();
5251 
5252  HasDefaultArg = true;
5253  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
5254  TemplateLoc,
5255  RAngleLoc,
5256  TypeParm,
5257  Converted);
5258  if (DI)
5259  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
5260 
5261  return TemplateArgumentLoc();
5262  }
5263 
5264  if (NonTypeTemplateParmDecl *NonTypeParm
5265  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5266  if (!hasVisibleDefaultArgument(NonTypeParm))
5267  return TemplateArgumentLoc();
5268 
5269  HasDefaultArg = true;
5270  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
5271  TemplateLoc,
5272  RAngleLoc,
5273  NonTypeParm,
5274  Converted);
5275  if (Arg.isInvalid())
5276  return TemplateArgumentLoc();
5277 
5278  Expr *ArgE = Arg.getAs<Expr>();
5279  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
5280  }
5281 
5282  TemplateTemplateParmDecl *TempTempParm
5283  = cast<TemplateTemplateParmDecl>(Param);
5284  if (!hasVisibleDefaultArgument(TempTempParm))
5285  return TemplateArgumentLoc();
5286 
5287  HasDefaultArg = true;
5288  NestedNameSpecifierLoc QualifierLoc;
5289  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
5290  TemplateLoc,
5291  RAngleLoc,
5292  TempTempParm,
5293  Converted,
5294  QualifierLoc);
5295  if (TName.isNull())
5296  return TemplateArgumentLoc();
5297 
5298  return TemplateArgumentLoc(
5299  Context, TemplateArgument(TName),
5300  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
5301  TempTempParm->getDefaultArgument().getTemplateNameLoc());
5302 }
5303 
5304 /// Convert a template-argument that we parsed as a type into a template, if
5305 /// possible. C++ permits injected-class-names to perform dual service as
5306 /// template template arguments and as template type arguments.
5307 static TemplateArgumentLoc
5309  // Extract and step over any surrounding nested-name-specifier.
5310  NestedNameSpecifierLoc QualLoc;
5311  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
5312  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
5313  return TemplateArgumentLoc();
5314 
5315  QualLoc = ETLoc.getQualifierLoc();
5316  TLoc = ETLoc.getNamedTypeLoc();
5317  }
5318  // If this type was written as an injected-class-name, it can be used as a
5319  // template template argument.
5320  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
5321  return TemplateArgumentLoc(Context, InjLoc.getTypePtr()->getTemplateName(),
5322  QualLoc, InjLoc.getNameLoc());
5323 
5324  // If this type was written as an injected-class-name, it may have been
5325  // converted to a RecordType during instantiation. If the RecordType is
5326  // *not* wrapped in a TemplateSpecializationType and denotes a class
5327  // template specialization, it must have come from an injected-class-name.
5328  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
5329  if (auto *CTSD =
5330  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
5331  return TemplateArgumentLoc(Context,
5332  TemplateName(CTSD->getSpecializedTemplate()),
5333  QualLoc, RecLoc.getNameLoc());
5334 
5335  return TemplateArgumentLoc();
5336 }
5337 
5338 /// Check that the given template argument corresponds to the given
5339 /// template parameter.
5340 ///
5341 /// \param Param The template parameter against which the argument will be
5342 /// checked.
5343 ///
5344 /// \param Arg The template argument, which may be updated due to conversions.
5345 ///
5346 /// \param Template The template in which the template argument resides.
5347 ///
5348 /// \param TemplateLoc The location of the template name for the template
5349 /// whose argument list we're matching.
5350 ///
5351 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
5352 /// the template argument list.
5353 ///
5354 /// \param ArgumentPackIndex The index into the argument pack where this
5355 /// argument will be placed. Only valid if the parameter is a parameter pack.
5356 ///
5357 /// \param Converted The checked, converted argument will be added to the
5358 /// end of this small vector.
5359 ///
5360 /// \param CTAK Describes how we arrived at this particular template argument:
5361 /// explicitly written, deduced, etc.
5362 ///
5363 /// \returns true on error, false otherwise.
5365  TemplateArgumentLoc &Arg,
5366  NamedDecl *Template,
5367  SourceLocation TemplateLoc,
5368  SourceLocation RAngleLoc,
5369  unsigned ArgumentPackIndex,
5372  // Check template type parameters.
5373  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
5374  return CheckTemplateTypeArgument(TTP, Arg, Converted);
5375 
5376  // Check non-type template parameters.
5377  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5378  // Do substitution on the type of the non-type template parameter
5379  // with the template arguments we've seen thus far. But if the
5380  // template has a dependent context then we cannot substitute yet.
5381  QualType NTTPType = NTTP->getType();
5382  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
5383  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
5384 
5385  if (NTTPType->isInstantiationDependentType() &&
5386  !isa<TemplateTemplateParmDecl>(Template) &&
5387  !Template->getDeclContext()->isDependentContext()) {
5388  // Do substitution on the type of the non-type template parameter.
5389  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5390  NTTP, Converted,
5391  SourceRange(TemplateLoc, RAngleLoc));
5392  if (Inst.isInvalid())
5393  return true;
5394 
5396  Converted);
5397 
5398  // If the parameter is a pack expansion, expand this slice of the pack.
5399  if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
5400  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
5401  ArgumentPackIndex);
5402  NTTPType = SubstType(PET->getPattern(),
5403  MultiLevelTemplateArgumentList(TemplateArgs),
5404  NTTP->getLocation(),
5405  NTTP->getDeclName());
5406  } else {
5407  NTTPType = SubstType(NTTPType,
5408  MultiLevelTemplateArgumentList(TemplateArgs),
5409  NTTP->getLocation(),
5410  NTTP->getDeclName());
5411  }
5412 
5413  // If that worked, check the non-type template parameter type
5414  // for validity.
5415  if (!NTTPType.isNull())
5416  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
5417  NTTP->getLocation());
5418  if (NTTPType.isNull())
5419  return true;
5420  }
5421 
5422  switch (Arg.getArgument().getKind()) {
5424  llvm_unreachable("Should never see a NULL template argument here");
5425 
5427  TemplateArgument Result;
5428  unsigned CurSFINAEErrors = NumSFINAEErrors;
5429  ExprResult Res =
5430  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
5431  Result, CTAK);
5432  if (Res.isInvalid())
5433  return true;
5434  // If the current template argument causes an error, give up now.
5435  if (CurSFINAEErrors < NumSFINAEErrors)
5436  return true;
5437 
5438  // If the resulting expression is new, then use it in place of the
5439  // old expression in the template argument.
5440  if (Res.get() != Arg.getArgument().getAsExpr()) {
5441  TemplateArgument TA(Res.get());
5442  Arg = TemplateArgumentLoc(TA, Res.get());
5443  }
5444 
5445  Converted.push_back(Result);
5446  break;
5447  }
5448 
5452  // We've already checked this template argument, so just copy
5453  // it to the list of converted arguments.
5454  Converted.push_back(Arg.getArgument());
5455  break;
5456 
5459  // We were given a template template argument. It may not be ill-formed;
5460  // see below.
5461  if (DependentTemplateName *DTN
5464  // We have a template argument such as \c T::template X, which we
5465  // parsed as a template template argument. However, since we now
5466  // know that we need a non-type template argument, convert this
5467  // template name into an expression.
5468 
5469  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
5470  Arg.getTemplateNameLoc());
5471 
5472  CXXScopeSpec SS;
5473  SS.Adopt(Arg.getTemplateQualifierLoc());
5474  // FIXME: the template-template arg was a DependentTemplateName,
5475  // so it was provided with a template keyword. However, its source
5476  // location is not stored in the template argument structure.
5477  SourceLocation TemplateKWLoc;
5479  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
5480  nullptr);
5481 
5482  // If we parsed the template argument as a pack expansion, create a
5483  // pack expansion expression.
5485  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
5486  if (E.isInvalid())
5487  return true;
5488  }
5489 
5490  TemplateArgument Result;
5491  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
5492  if (E.isInvalid())
5493  return true;
5494 
5495  Converted.push_back(Result);
5496  break;
5497  }
5498 
5499  // We have a template argument that actually does refer to a class
5500  // template, alias template, or template template parameter, and
5501  // therefore cannot be a non-type template argument.
5502  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
5503  << Arg.getSourceRange();
5504 
5505  Diag(Param->getLocation(), diag::note_template_param_here);
5506  return true;
5507 
5508  case TemplateArgument::Type: {
5509  // We have a non-type template parameter but the template
5510  // argument is a type.
5511 
5512  // C++ [temp.arg]p2:
5513  // In a template-argument, an ambiguity between a type-id and
5514  // an expression is resolved to a type-id, regardless of the
5515  // form of the corresponding template-parameter.
5516  //
5517  // We warn specifically about this case, since it can be rather
5518  // confusing for users.
5519  QualType T = Arg.getArgument().getAsType();
5520  SourceRange SR = Arg.getSourceRange();
5521  if (T->isFunctionType())
5522  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
5523  else
5524  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
5525  Diag(Param->getLocation(), diag::note_template_param_here);
5526  return true;
5527  }
5528 
5530  llvm_unreachable("Caller must expand template argument packs");
5531  }
5532 
5533  return false;
5534  }
5535 
5536 
5537  // Check template template parameters.
5538  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
5539 
5540  TemplateParameterList *Params = TempParm->getTemplateParameters();
5541  if (TempParm->isExpandedParameterPack())
5542  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
5543 
5544  // Substitute into the template parameter list of the template
5545  // template parameter, since previously-supplied template arguments
5546  // may appear within the template template parameter.
5547  //
5548  // FIXME: Skip this if the parameters aren't instantiation-dependent.
5549  {
5550  // Set up a template instantiation context.
5552  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5553  TempParm, Converted,
5554  SourceRange(TemplateLoc, RAngleLoc));
5555  if (Inst.isInvalid())
5556  return true;
5557 
5558  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5559  Params = SubstTemplateParams(Params, CurContext,
5560  MultiLevelTemplateArgumentList(TemplateArgs));
5561  if (!Params)
5562  return true;
5563  }
5564 
5565  // C++1z [temp.local]p1: (DR1004)
5566  // When [the injected-class-name] is used [...] as a template-argument for
5567  // a template template-parameter [...] it refers to the class template
5568  // itself.
5569  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
5571  Context, Arg.getTypeSourceInfo()->getTypeLoc());
5572  if (!ConvertedArg.getArgument().isNull())
5573  Arg = ConvertedArg;
5574  }
5575 
5576  switch (Arg.getArgument().getKind()) {
5578  llvm_unreachable("Should never see a NULL template argument here");
5579 
5582  if (CheckTemplateTemplateArgument(TempParm, Params, Arg))
5583  return true;
5584 
5585  Converted.push_back(Arg.getArgument());
5586  break;
5587 
5590  // We have a template template parameter but the template
5591  // argument does not refer to a template.
5592  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
5593  << getLangOpts().CPlusPlus11;
5594  return true;
5595 
5597  llvm_unreachable("Declaration argument with template template parameter");
5599  llvm_unreachable("Integral argument with template template parameter");
5601  llvm_unreachable("Null pointer argument with template template parameter");
5602 
5604  llvm_unreachable("Caller must expand template argument packs");
5605  }
5606 
5607  return false;
5608 }
5609 
5610 /// Diagnose a missing template argument.
5611 template<typename TemplateParmDecl>
5613  TemplateDecl *TD,
5614  const TemplateParmDecl *D,
5615  TemplateArgumentListInfo &Args) {
5616  // Dig out the most recent declaration of the template parameter; there may be
5617  // declarations of the template that are more recent than TD.
5618  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
5619  ->getTemplateParameters()
5620  ->getParam(D->getIndex()));
5621 
5622  // If there's a default argument that's not visible, diagnose that we're
5623  // missing a module import.
5625  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5626  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5627  D->getDefaultArgumentLoc(), Modules,
5629  /*Recover*/true);
5630  return true;
5631  }
5632 
5633  // FIXME: If there's a more recent default argument that *is* visible,
5634  // diagnose that it was declared too late.
5635 
5637 
5638  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5639  << /*not enough args*/0