clang  12.0.0git
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.
269  R.suppressDiagnostics();
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.
296  R.suppressDiagnostics();
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  ConceptDecl *CD =
1109  cast<ConceptDecl>(TypeConstr->Template.get().getAsTemplateDecl());
1110 
1111  // C++2a [temp.param]p4:
1112  // [...] The concept designated by a type-constraint shall be a type
1113  // concept ([temp.concept]).
1114  if (!CD->isTypeConcept()) {
1115  Diag(TypeConstr->TemplateNameLoc,
1116  diag::err_type_constraint_non_type_concept);
1117  return true;
1118  }
1119 
1120  bool WereArgsSpecified = TypeConstr->LAngleLoc.isValid();
1121 
1122  if (!WereArgsSpecified &&
1124  Diag(TypeConstr->TemplateNameLoc,
1125  diag::err_type_constraint_missing_arguments) << CD;
1126  return true;
1127  }
1128 
1129  TemplateArgumentListInfo TemplateArgs;
1130  if (TypeConstr->LAngleLoc.isValid()) {
1131  TemplateArgs =
1132  makeTemplateArgumentListInfo(*this, *TypeConstr);
1133  }
1134  return AttachTypeConstraint(
1135  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc(),
1137  TypeConstr->TemplateNameLoc), CD,
1138  TypeConstr->LAngleLoc.isValid() ? &TemplateArgs : nullptr,
1139  ConstrainedParameter, EllipsisLoc);
1140 }
1141 
1142 template<typename ArgumentLocAppender>
1145  ConceptDecl *NamedConcept, SourceLocation LAngleLoc,
1146  SourceLocation RAngleLoc, QualType ConstrainedType,
1147  SourceLocation ParamNameLoc, ArgumentLocAppender Appender,
1148  SourceLocation EllipsisLoc) {
1149 
1150  TemplateArgumentListInfo ConstraintArgs;
1151  ConstraintArgs.addArgument(
1153  /*NTTPType=*/QualType(), ParamNameLoc));
1154 
1155  ConstraintArgs.setRAngleLoc(RAngleLoc);
1156  ConstraintArgs.setLAngleLoc(LAngleLoc);
1157  Appender(ConstraintArgs);
1158 
1159  // C++2a [temp.param]p4:
1160  // [...] This constraint-expression E is called the immediately-declared
1161  // constraint of T. [...]
1162  CXXScopeSpec SS;
1163  SS.Adopt(NS);
1164  ExprResult ImmediatelyDeclaredConstraint = S.CheckConceptTemplateId(
1165  SS, /*TemplateKWLoc=*/SourceLocation(), NameInfo,
1166  /*FoundDecl=*/NamedConcept, NamedConcept, &ConstraintArgs);
1167  if (ImmediatelyDeclaredConstraint.isInvalid() || !EllipsisLoc.isValid())
1168  return ImmediatelyDeclaredConstraint;
1169 
1170  // C++2a [temp.param]p4:
1171  // [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
1172  //
1173  // We have the following case:
1174  //
1175  // template<typename T> concept C1 = true;
1176  // template<C1... T> struct s1;
1177  //
1178  // The constraint: (C1<T> && ...)
1179  //
1180  // Note that the type of C1<T> is known to be 'bool', so we don't need to do
1181  // any unqualified lookups for 'operator&&' here.
1182  return S.BuildCXXFoldExpr(/*UnqualifiedLookup=*/nullptr,
1183  /*LParenLoc=*/SourceLocation(),
1184  ImmediatelyDeclaredConstraint.get(), BO_LAnd,
1185  EllipsisLoc, /*RHS=*/nullptr,
1186  /*RParenLoc=*/SourceLocation(),
1187  /*NumExpansions=*/None);
1188 }
1189 
1190 /// Attach a type-constraint to a template parameter.
1191 /// \returns true if an error occured. This can happen if the
1192 /// immediately-declared constraint could not be formed (e.g. incorrect number
1193 /// of arguments for the named concept).
1195  DeclarationNameInfo NameInfo,
1196  ConceptDecl *NamedConcept,
1197  const TemplateArgumentListInfo *TemplateArgs,
1198  TemplateTypeParmDecl *ConstrainedParameter,
1199  SourceLocation EllipsisLoc) {
1200  // C++2a [temp.param]p4:
1201  // [...] If Q is of the form C<A1, ..., An>, then let E' be
1202  // C<T, A1, ..., An>. Otherwise, let E' be C<T>. [...]
1203  const ASTTemplateArgumentListInfo *ArgsAsWritten =
1204  TemplateArgs ? ASTTemplateArgumentListInfo::Create(Context,
1205  *TemplateArgs) : nullptr;
1206 
1207  QualType ParamAsArgument(ConstrainedParameter->getTypeForDecl(), 0);
1208 
1209  ExprResult ImmediatelyDeclaredConstraint =
1211  *this, NS, NameInfo, NamedConcept,
1212  TemplateArgs ? TemplateArgs->getLAngleLoc() : SourceLocation(),
1213  TemplateArgs ? TemplateArgs->getRAngleLoc() : SourceLocation(),
1214  ParamAsArgument, ConstrainedParameter->getLocation(),
1215  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1216  if (TemplateArgs)
1217  for (const auto &ArgLoc : TemplateArgs->arguments())
1218  ConstraintArgs.addArgument(ArgLoc);
1219  }, EllipsisLoc);
1220  if (ImmediatelyDeclaredConstraint.isInvalid())
1221  return true;
1222 
1223  ConstrainedParameter->setTypeConstraint(NS, NameInfo,
1224  /*FoundDecl=*/NamedConcept,
1225  NamedConcept, ArgsAsWritten,
1226  ImmediatelyDeclaredConstraint.get());
1227  return false;
1228 }
1229 
1231  SourceLocation EllipsisLoc) {
1232  if (NTTP->getType() != TL.getType() ||
1235  diag::err_unsupported_placeholder_constraint)
1237  return true;
1238  }
1239  // FIXME: Concepts: This should be the type of the placeholder, but this is
1240  // unclear in the wording right now.
1241  DeclRefExpr *Ref = BuildDeclRefExpr(NTTP, NTTP->getType(), VK_RValue,
1242  NTTP->getLocation());
1243  if (!Ref)
1244  return true;
1245  ExprResult ImmediatelyDeclaredConstraint =
1248  TL.getNamedConcept(), TL.getLAngleLoc(), TL.getRAngleLoc(),
1249  BuildDecltypeType(Ref, NTTP->getLocation()), NTTP->getLocation(),
1250  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1251  for (unsigned I = 0, C = TL.getNumArgs(); I != C; ++I)
1252  ConstraintArgs.addArgument(TL.getArgLoc(I));
1253  }, EllipsisLoc);
1254  if (ImmediatelyDeclaredConstraint.isInvalid() ||
1255  !ImmediatelyDeclaredConstraint.isUsable())
1256  return true;
1257 
1258  NTTP->setPlaceholderTypeConstraint(ImmediatelyDeclaredConstraint.get());
1259  return false;
1260 }
1261 
1262 /// Check that the type of a non-type template parameter is
1263 /// well-formed.
1264 ///
1265 /// \returns the (possibly-promoted) parameter type if valid;
1266 /// otherwise, produces a diagnostic and returns a NULL type.
1268  SourceLocation Loc) {
1269  if (TSI->getType()->isUndeducedType()) {
1270  // C++17 [temp.dep.expr]p3:
1271  // An id-expression is type-dependent if it contains
1272  // - an identifier associated by name lookup with a non-type
1273  // template-parameter declared with a type that contains a
1274  // placeholder type (7.1.7.4),
1275  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
1276  }
1277 
1278  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
1279 }
1280 
1281 /// Require the given type to be a structural type, and diagnose if it is not.
1282 ///
1283 /// \return \c true if an error was produced.
1285  if (T->isDependentType())
1286  return false;
1287 
1288  if (RequireCompleteType(Loc, T, diag::err_template_nontype_parm_incomplete))
1289  return true;
1290 
1291  if (T->isStructuralType())
1292  return false;
1293 
1294  // Structural types are required to be object types or lvalue references.
1295  if (T->isRValueReferenceType()) {
1296  Diag(Loc, diag::err_template_nontype_parm_rvalue_ref) << T;
1297  return true;
1298  }
1299 
1300  // Don't mention structural types in our diagnostic prior to C++20. Also,
1301  // there's not much more we can say about non-scalar non-class types --
1302  // because we can't see functions or arrays here, those can only be language
1303  // extensions.
1304  if (!getLangOpts().CPlusPlus20 ||
1305  (!T->isScalarType() && !T->isRecordType())) {
1306  Diag(Loc, diag::err_template_nontype_parm_bad_type) << T;
1307  return true;
1308  }
1309 
1310  // Structural types are required to be literal types.
1311  if (RequireLiteralType(Loc, T, diag::err_template_nontype_parm_not_literal))
1312  return true;
1313 
1314  Diag(Loc, diag::err_template_nontype_parm_not_structural) << T;
1315 
1316  // Drill down into the reason why the class is non-structural.
1317  while (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
1318  // All members are required to be public and non-mutable, and can't be of
1319  // rvalue reference type. Check these conditions first to prefer a "local"
1320  // reason over a more distant one.
1321  for (const FieldDecl *FD : RD->fields()) {
1322  if (FD->getAccess() != AS_public) {
1323  Diag(FD->getLocation(), diag::note_not_structural_non_public) << T << 0;
1324  return true;
1325  }
1326  if (FD->isMutable()) {
1327  Diag(FD->getLocation(), diag::note_not_structural_mutable_field) << T;
1328  return true;
1329  }
1330  if (FD->getType()->isRValueReferenceType()) {
1331  Diag(FD->getLocation(), diag::note_not_structural_rvalue_ref_field)
1332  << T;
1333  return true;
1334  }
1335  }
1336 
1337  // All bases are required to be public.
1338  for (const auto &BaseSpec : RD->bases()) {
1339  if (BaseSpec.getAccessSpecifier() != AS_public) {
1340  Diag(BaseSpec.getBaseTypeLoc(), diag::note_not_structural_non_public)
1341  << T << 1;
1342  return true;
1343  }
1344  }
1345 
1346  // All subobjects are required to be of structural types.
1347  SourceLocation SubLoc;
1348  QualType SubType;
1349  int Kind = -1;
1350 
1351  for (const FieldDecl *FD : RD->fields()) {
1352  QualType T = Context.getBaseElementType(FD->getType());
1353  if (!T->isStructuralType()) {
1354  SubLoc = FD->getLocation();
1355  SubType = T;
1356  Kind = 0;
1357  break;
1358  }
1359  }
1360 
1361  if (Kind == -1) {
1362  for (const auto &BaseSpec : RD->bases()) {
1363  QualType T = BaseSpec.getType();
1364  if (!T->isStructuralType()) {
1365  SubLoc = BaseSpec.getBaseTypeLoc();
1366  SubType = T;
1367  Kind = 1;
1368  break;
1369  }
1370  }
1371  }
1372 
1373  assert(Kind != -1 && "couldn't find reason why type is not structural");
1374  Diag(SubLoc, diag::note_not_structural_subobject)
1375  << T << Kind << SubType;
1376  T = SubType;
1377  RD = T->getAsCXXRecordDecl();
1378  }
1379 
1380  return true;
1381 }
1382 
1384  SourceLocation Loc) {
1385  // We don't allow variably-modified types as the type of non-type template
1386  // parameters.
1387  if (T->isVariablyModifiedType()) {
1388  Diag(Loc, diag::err_variably_modified_nontype_template_param)
1389  << T;
1390  return QualType();
1391  }
1392 
1393  // C++ [temp.param]p4:
1394  //
1395  // A non-type template-parameter shall have one of the following
1396  // (optionally cv-qualified) types:
1397  //
1398  // -- integral or enumeration type,
1399  if (T->isIntegralOrEnumerationType() ||
1400  // -- pointer to object or pointer to function,
1401  T->isPointerType() ||
1402  // -- lvalue reference to object or lvalue reference to function,
1403  T->isLValueReferenceType() ||
1404  // -- pointer to member,
1405  T->isMemberPointerType() ||
1406  // -- std::nullptr_t, or
1407  T->isNullPtrType() ||
1408  // -- a type that contains a placeholder type.
1409  T->isUndeducedType()) {
1410  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1411  // are ignored when determining its type.
1412  return T.getUnqualifiedType();
1413  }
1414 
1415  // C++ [temp.param]p8:
1416  //
1417  // A non-type template-parameter of type "array of T" or
1418  // "function returning T" is adjusted to be of type "pointer to
1419  // T" or "pointer to function returning T", respectively.
1420  if (T->isArrayType() || T->isFunctionType())
1421  return Context.getDecayedType(T);
1422 
1423  // If T is a dependent type, we can't do the check now, so we
1424  // assume that it is well-formed. Note that stripping off the
1425  // qualifiers here is not really correct if T turns out to be
1426  // an array type, but we'll recompute the type everywhere it's
1427  // used during instantiation, so that should be OK. (Using the
1428  // qualified type is equally wrong.)
1429  if (T->isDependentType())
1430  return T.getUnqualifiedType();
1431 
1432  // C++20 [temp.param]p6:
1433  // -- a structural type
1434  if (RequireStructuralType(T, Loc))
1435  return QualType();
1436 
1437  if (!getLangOpts().CPlusPlus20) {
1438  // FIXME: Consider allowing structural types as an extension in C++17. (In
1439  // earlier language modes, the template argument evaluation rules are too
1440  // inflexible.)
1441  Diag(Loc, diag::err_template_nontype_parm_bad_structural_type) << T;
1442  return QualType();
1443  }
1444 
1445  Diag(Loc, diag::warn_cxx17_compat_template_nontype_parm_type) << T;
1446  return T.getUnqualifiedType();
1447 }
1448 
1450  unsigned Depth,
1451  unsigned Position,
1452  SourceLocation EqualLoc,
1453  Expr *Default) {
1454  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1455 
1456  // Check that we have valid decl-specifiers specified.
1457  auto CheckValidDeclSpecifiers = [this, &D] {
1458  // C++ [temp.param]
1459  // p1
1460  // template-parameter:
1461  // ...
1462  // parameter-declaration
1463  // p2
1464  // ... A storage class shall not be specified in a template-parameter
1465  // declaration.
1466  // [dcl.typedef]p1:
1467  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1468  // of a parameter-declaration
1469  const DeclSpec &DS = D.getDeclSpec();
1470  auto EmitDiag = [this](SourceLocation Loc) {
1471  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1472  << FixItHint::CreateRemoval(Loc);
1473  };
1475  EmitDiag(DS.getStorageClassSpecLoc());
1476 
1478  EmitDiag(DS.getThreadStorageClassSpecLoc());
1479 
1480  // [dcl.inline]p1:
1481  // The inline specifier can be applied only to the declaration or
1482  // definition of a variable or function.
1483 
1484  if (DS.isInlineSpecified())
1485  EmitDiag(DS.getInlineSpecLoc());
1486 
1487  // [dcl.constexpr]p1:
1488  // The constexpr specifier shall be applied only to the definition of a
1489  // variable or variable template or the declaration of a function or
1490  // function template.
1491 
1492  if (DS.hasConstexprSpecifier())
1493  EmitDiag(DS.getConstexprSpecLoc());
1494 
1495  // [dcl.fct.spec]p1:
1496  // Function-specifiers can be used only in function declarations.
1497 
1498  if (DS.isVirtualSpecified())
1499  EmitDiag(DS.getVirtualSpecLoc());
1500 
1501  if (DS.hasExplicitSpecifier())
1502  EmitDiag(DS.getExplicitSpecLoc());
1503 
1504  if (DS.isNoreturnSpecified())
1505  EmitDiag(DS.getNoreturnSpecLoc());
1506  };
1507 
1508  CheckValidDeclSpecifiers();
1509 
1510  if (TInfo->getType()->isUndeducedType()) {
1511  Diag(D.getIdentifierLoc(),
1512  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1513  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1514  }
1515 
1516  assert(S->isTemplateParamScope() &&
1517  "Non-type template parameter not in template parameter scope!");
1518  bool Invalid = false;
1519 
1520  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1521  if (T.isNull()) {
1522  T = Context.IntTy; // Recover with an 'int' type.
1523  Invalid = true;
1524  }
1525 
1526  CheckFunctionOrTemplateParamDeclarator(S, D);
1527 
1528  IdentifierInfo *ParamName = D.getIdentifier();
1529  bool IsParameterPack = D.hasEllipsis();
1531  Context, Context.getTranslationUnitDecl(), D.getBeginLoc(),
1532  D.getIdentifierLoc(), Depth, Position, ParamName, T, IsParameterPack,
1533  TInfo);
1534  Param->setAccess(AS_public);
1535 
1536  if (AutoTypeLoc TL = TInfo->getTypeLoc().getContainedAutoTypeLoc())
1537  if (TL.isConstrained())
1538  if (AttachTypeConstraint(TL, Param, D.getEllipsisLoc()))
1539  Invalid = true;
1540 
1541  if (Invalid)
1542  Param->setInvalidDecl();
1543 
1544  if (Param->isParameterPack())
1545  if (auto *LSI = getEnclosingLambda())
1546  LSI->LocalPacks.push_back(Param);
1547 
1548  if (ParamName) {
1550  ParamName);
1551 
1552  // Add the template parameter into the current scope.
1553  S->AddDecl(Param);
1554  IdResolver.AddDecl(Param);
1555  }
1556 
1557  // C++0x [temp.param]p9:
1558  // A default template-argument may be specified for any kind of
1559  // template-parameter that is not a template parameter pack.
1560  if (Default && IsParameterPack) {
1561  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1562  Default = nullptr;
1563  }
1564 
1565  // Check the well-formedness of the default template argument, if provided.
1566  if (Default) {
1567  // Check for unexpanded parameter packs.
1568  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1569  return Param;
1570 
1571  TemplateArgument Converted;
1572  ExprResult DefaultRes =
1573  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1574  if (DefaultRes.isInvalid()) {
1575  Param->setInvalidDecl();
1576  return Param;
1577  }
1578  Default = DefaultRes.get();
1579 
1580  Param->setDefaultArgument(Default);
1581  }
1582 
1583  return Param;
1584 }
1585 
1586 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1587 /// parameter (e.g. T in template <template <typename> class T> class array)
1588 /// has been parsed. S is the current scope.
1590  SourceLocation TmpLoc,
1591  TemplateParameterList *Params,
1592  SourceLocation EllipsisLoc,
1593  IdentifierInfo *Name,
1594  SourceLocation NameLoc,
1595  unsigned Depth,
1596  unsigned Position,
1597  SourceLocation EqualLoc,
1598  ParsedTemplateArgument Default) {
1599  assert(S->isTemplateParamScope() &&
1600  "Template template parameter not in template parameter scope!");
1601 
1602  // Construct the parameter object.
1603  bool IsParameterPack = EllipsisLoc.isValid();
1604  TemplateTemplateParmDecl *Param =
1606  NameLoc.isInvalid()? TmpLoc : NameLoc,
1607  Depth, Position, IsParameterPack,
1608  Name, Params);
1609  Param->setAccess(AS_public);
1610 
1611  if (Param->isParameterPack())
1612  if (auto *LSI = getEnclosingLambda())
1613  LSI->LocalPacks.push_back(Param);
1614 
1615  // If the template template parameter has a name, then link the identifier
1616  // into the scope and lookup mechanisms.
1617  if (Name) {
1618  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1619 
1620  S->AddDecl(Param);
1621  IdResolver.AddDecl(Param);
1622  }
1623 
1624  if (Params->size() == 0) {
1625  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1626  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1627  Param->setInvalidDecl();
1628  }
1629 
1630  // C++0x [temp.param]p9:
1631  // A default template-argument may be specified for any kind of
1632  // template-parameter that is not a template parameter pack.
1633  if (IsParameterPack && !Default.isInvalid()) {
1634  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1636  }
1637 
1638  if (!Default.isInvalid()) {
1639  // Check only that we have a template template argument. We don't want to
1640  // try to check well-formedness now, because our template template parameter
1641  // might have dependent types in its template parameters, which we wouldn't
1642  // be able to match now.
1643  //
1644  // If none of the template template parameter's template arguments mention
1645  // other template parameters, we could actually perform more checking here.
1646  // However, it isn't worth doing.
1648  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1649  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1650  << DefaultArg.getSourceRange();
1651  return Param;
1652  }
1653 
1654  // Check for unexpanded parameter packs.
1655  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1656  DefaultArg.getArgument().getAsTemplate(),
1657  UPPC_DefaultArgument))
1658  return Param;
1659 
1660  Param->setDefaultArgument(Context, DefaultArg);
1661  }
1662 
1663  return Param;
1664 }
1665 
1666 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1667 /// constrained by RequiresClause, that contains the template parameters in
1668 /// Params.
1671  SourceLocation ExportLoc,
1672  SourceLocation TemplateLoc,
1673  SourceLocation LAngleLoc,
1674  ArrayRef<NamedDecl *> Params,
1675  SourceLocation RAngleLoc,
1676  Expr *RequiresClause) {
1677  if (ExportLoc.isValid())
1678  Diag(ExportLoc, diag::warn_template_export_unsupported);
1679 
1681  Context, TemplateLoc, LAngleLoc,
1682  llvm::makeArrayRef(Params.data(), Params.size()),
1683  RAngleLoc, RequiresClause);
1684 }
1685 
1687  const CXXScopeSpec &SS) {
1688  if (SS.isSet())
1690 }
1691 
1693  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1694  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1695  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1696  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1697  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1698  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1699  assert(TemplateParams && TemplateParams->size() > 0 &&
1700  "No template parameters");
1701  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1702  bool Invalid = false;
1703 
1704  // Check that we can declare a template here.
1705  if (CheckTemplateDeclScope(S, TemplateParams))
1706  return true;
1707 
1709  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1710 
1711  // There is no such thing as an unnamed class template.
1712  if (!Name) {
1713  Diag(KWLoc, diag::err_template_unnamed_class);
1714  return true;
1715  }
1716 
1717  // Find any previous declaration with this name. For a friend with no
1718  // scope explicitly specified, we only look for tag declarations (per
1719  // C++11 [basic.lookup.elab]p2).
1720  DeclContext *SemanticContext;
1721  LookupResult Previous(*this, Name, NameLoc,
1722  (SS.isEmpty() && TUK == TUK_Friend)
1723  ? LookupTagName : LookupOrdinaryName,
1724  forRedeclarationInCurContext());
1725  if (SS.isNotEmpty() && !SS.isInvalid()) {
1726  SemanticContext = computeDeclContext(SS, true);
1727  if (!SemanticContext) {
1728  // FIXME: Horrible, horrible hack! We can't currently represent this
1729  // in the AST, and historically we have just ignored such friend
1730  // class templates, so don't complain here.
1731  Diag(NameLoc, TUK == TUK_Friend
1732  ? diag::warn_template_qualified_friend_ignored
1733  : diag::err_template_qualified_declarator_no_match)
1734  << SS.getScopeRep() << SS.getRange();
1735  return TUK != TUK_Friend;
1736  }
1737 
1738  if (RequireCompleteDeclContext(SS, SemanticContext))
1739  return true;
1740 
1741  // If we're adding a template to a dependent context, we may need to
1742  // rebuilding some of the types used within the template parameter list,
1743  // now that we know what the current instantiation is.
1744  if (SemanticContext->isDependentContext()) {
1745  ContextRAII SavedContext(*this, SemanticContext);
1746  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1747  Invalid = true;
1748  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1749  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1750 
1751  LookupQualifiedName(Previous, SemanticContext);
1752  } else {
1753  SemanticContext = CurContext;
1754 
1755  // C++14 [class.mem]p14:
1756  // If T is the name of a class, then each of the following shall have a
1757  // name different from T:
1758  // -- every member template of class T
1759  if (TUK != TUK_Friend &&
1760  DiagnoseClassNameShadow(SemanticContext,
1761  DeclarationNameInfo(Name, NameLoc)))
1762  return true;
1763 
1764  LookupName(Previous, S);
1765  }
1766 
1767  if (Previous.isAmbiguous())
1768  return true;
1769 
1770  NamedDecl *PrevDecl = nullptr;
1771  if (Previous.begin() != Previous.end())
1772  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1773 
1774  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1775  // Maybe we will complain about the shadowed template parameter.
1776  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1777  // Just pretend that we didn't see the previous declaration.
1778  PrevDecl = nullptr;
1779  }
1780 
1781  // If there is a previous declaration with the same name, check
1782  // whether this is a valid redeclaration.
1783  ClassTemplateDecl *PrevClassTemplate =
1784  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1785 
1786  // We may have found the injected-class-name of a class template,
1787  // class template partial specialization, or class template specialization.
1788  // In these cases, grab the template that is being defined or specialized.
1789  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1790  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1791  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1792  PrevClassTemplate
1793  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1794  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1795  PrevClassTemplate
1796  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1797  ->getSpecializedTemplate();
1798  }
1799  }
1800 
1801  if (TUK == TUK_Friend) {
1802  // C++ [namespace.memdef]p3:
1803  // [...] When looking for a prior declaration of a class or a function
1804  // declared as a friend, and when the name of the friend class or
1805  // function is neither a qualified name nor a template-id, scopes outside
1806  // the innermost enclosing namespace scope are not considered.
1807  if (!SS.isSet()) {
1808  DeclContext *OutermostContext = CurContext;
1809  while (!OutermostContext->isFileContext())
1810  OutermostContext = OutermostContext->getLookupParent();
1811 
1812  if (PrevDecl &&
1813  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1814  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1815  SemanticContext = PrevDecl->getDeclContext();
1816  } else {
1817  // Declarations in outer scopes don't matter. However, the outermost
1818  // context we computed is the semantic context for our new
1819  // declaration.
1820  PrevDecl = PrevClassTemplate = nullptr;
1821  SemanticContext = OutermostContext;
1822 
1823  // Check that the chosen semantic context doesn't already contain a
1824  // declaration of this name as a non-tag type.
1825  Previous.clear(LookupOrdinaryName);
1826  DeclContext *LookupContext = SemanticContext;
1827  while (LookupContext->isTransparentContext())
1828  LookupContext = LookupContext->getLookupParent();
1829  LookupQualifiedName(Previous, LookupContext);
1830 
1831  if (Previous.isAmbiguous())
1832  return true;
1833 
1834  if (Previous.begin() != Previous.end())
1835  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1836  }
1837  }
1838  } else if (PrevDecl &&
1839  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1840  S, SS.isValid()))
1841  PrevDecl = PrevClassTemplate = nullptr;
1842 
1843  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1844  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1845  if (SS.isEmpty() &&
1846  !(PrevClassTemplate &&
1847  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1848  SemanticContext->getRedeclContext()))) {
1849  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1850  Diag(Shadow->getTargetDecl()->getLocation(),
1851  diag::note_using_decl_target);
1852  Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1853  // Recover by ignoring the old declaration.
1854  PrevDecl = PrevClassTemplate = nullptr;
1855  }
1856  }
1857 
1858  if (PrevClassTemplate) {
1859  // Ensure that the template parameter lists are compatible. Skip this check
1860  // for a friend in a dependent context: the template parameter list itself
1861  // could be dependent.
1862  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1863  !TemplateParameterListsAreEqual(TemplateParams,
1864  PrevClassTemplate->getTemplateParameters(),
1865  /*Complain=*/true,
1866  TPL_TemplateMatch))
1867  return true;
1868 
1869  // C++ [temp.class]p4:
1870  // In a redeclaration, partial specialization, explicit
1871  // specialization or explicit instantiation of a class template,
1872  // the class-key shall agree in kind with the original class
1873  // template declaration (7.1.5.3).
1874  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1875  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1876  TUK == TUK_Definition, KWLoc, Name)) {
1877  Diag(KWLoc, diag::err_use_with_wrong_tag)
1878  << Name
1879  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1880  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1881  Kind = PrevRecordDecl->getTagKind();
1882  }
1883 
1884  // Check for redefinition of this class template.
1885  if (TUK == TUK_Definition) {
1886  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1887  // If we have a prior definition that is not visible, treat this as
1888  // simply making that previous definition visible.
1889  NamedDecl *Hidden = nullptr;
1890  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1891  SkipBody->ShouldSkip = true;
1892  SkipBody->Previous = Def;
1893  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1894  assert(Tmpl && "original definition of a class template is not a "
1895  "class template?");
1896  makeMergedDefinitionVisible(Hidden);
1897  makeMergedDefinitionVisible(Tmpl);
1898  } else {
1899  Diag(NameLoc, diag::err_redefinition) << Name;
1900  Diag(Def->getLocation(), diag::note_previous_definition);
1901  // FIXME: Would it make sense to try to "forget" the previous
1902  // definition, as part of error recovery?
1903  return true;
1904  }
1905  }
1906  }
1907  } else if (PrevDecl) {
1908  // C++ [temp]p5:
1909  // A class template shall not have the same name as any other
1910  // template, class, function, object, enumeration, enumerator,
1911  // namespace, or type in the same scope (3.3), except as specified
1912  // in (14.5.4).
1913  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1914  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1915  return true;
1916  }
1917 
1918  // Check the template parameter list of this declaration, possibly
1919  // merging in the template parameter list from the previous class
1920  // template declaration. Skip this check for a friend in a dependent
1921  // context, because the template parameter list might be dependent.
1922  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1923  CheckTemplateParameterList(
1924  TemplateParams,
1925  PrevClassTemplate
1926  ? PrevClassTemplate->getMostRecentDecl()->getTemplateParameters()
1927  : nullptr,
1928  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1929  SemanticContext->isDependentContext())
1930  ? TPC_ClassTemplateMember
1931  : TUK == TUK_Friend ? TPC_FriendClassTemplate : TPC_ClassTemplate,
1932  SkipBody))
1933  Invalid = true;
1934 
1935  if (SS.isSet()) {
1936  // If the name of the template was qualified, we must be defining the
1937  // template out-of-line.
1938  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1939  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1940  : diag::err_member_decl_does_not_match)
1941  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1942  Invalid = true;
1943  }
1944  }
1945 
1946  // If this is a templated friend in a dependent context we should not put it
1947  // on the redecl chain. In some cases, the templated friend can be the most
1948  // recent declaration tricking the template instantiator to make substitutions
1949  // there.
1950  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1951  bool ShouldAddRedecl
1952  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1953 
1954  CXXRecordDecl *NewClass =
1955  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1956  PrevClassTemplate && ShouldAddRedecl ?
1957  PrevClassTemplate->getTemplatedDecl() : nullptr,
1958  /*DelayTypeCreation=*/true);
1959  SetNestedNameSpecifier(*this, NewClass, SS);
1960  if (NumOuterTemplateParamLists > 0)
1962  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1963  NumOuterTemplateParamLists));
1964 
1965  // Add alignment attributes if necessary; these attributes are checked when
1966  // the ASTContext lays out the structure.
1967  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
1968  AddAlignmentAttributesForRecord(NewClass);
1969  AddMsStructLayoutForRecord(NewClass);
1970  }
1971 
1972  ClassTemplateDecl *NewTemplate
1973  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1974  DeclarationName(Name), TemplateParams,
1975  NewClass);
1976 
1977  if (ShouldAddRedecl)
1978  NewTemplate->setPreviousDecl(PrevClassTemplate);
1979 
1980  NewClass->setDescribedClassTemplate(NewTemplate);
1981 
1982  if (ModulePrivateLoc.isValid())
1983  NewTemplate->setModulePrivate();
1984 
1985  // Build the type for the class template declaration now.
1986  QualType T = NewTemplate->getInjectedClassNameSpecialization();
1987  T = Context.getInjectedClassNameType(NewClass, T);
1988  assert(T->isDependentType() && "Class template type is not dependent?");
1989  (void)T;
1990 
1991  // If we are providing an explicit specialization of a member that is a
1992  // class template, make a note of that.
1993  if (PrevClassTemplate &&
1994  PrevClassTemplate->getInstantiatedFromMemberTemplate())
1995  PrevClassTemplate->setMemberSpecialization();
1996 
1997  // Set the access specifier.
1998  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1999  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
2000 
2001  // Set the lexical context of these templates
2002  NewClass->setLexicalDeclContext(CurContext);
2003  NewTemplate->setLexicalDeclContext(CurContext);
2004 
2005  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
2006  NewClass->startDefinition();
2007 
2008  ProcessDeclAttributeList(S, NewClass, Attr);
2009 
2010  if (PrevClassTemplate)
2011  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
2012 
2013  AddPushedVisibilityAttribute(NewClass);
2014  inferGslOwnerPointerAttribute(NewClass);
2015 
2016  if (TUK != TUK_Friend) {
2017  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
2018  Scope *Outer = S;
2019  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
2020  Outer = Outer->getParent();
2021  PushOnScopeChains(NewTemplate, Outer);
2022  } else {
2023  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
2024  NewTemplate->setAccess(PrevClassTemplate->getAccess());
2025  NewClass->setAccess(PrevClassTemplate->getAccess());
2026  }
2027 
2028  NewTemplate->setObjectOfFriendDecl();
2029 
2030  // Friend templates are visible in fairly strange ways.
2031  if (!CurContext->isDependentContext()) {
2032  DeclContext *DC = SemanticContext->getRedeclContext();
2033  DC->makeDeclVisibleInContext(NewTemplate);
2034  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
2035  PushOnScopeChains(NewTemplate, EnclosingScope,
2036  /* AddToContext = */ false);
2037  }
2038 
2039  FriendDecl *Friend = FriendDecl::Create(
2040  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
2041  Friend->setAccess(AS_public);
2042  CurContext->addDecl(Friend);
2043  }
2044 
2045  if (PrevClassTemplate)
2046  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
2047 
2048  if (Invalid) {
2049  NewTemplate->setInvalidDecl();
2050  NewClass->setInvalidDecl();
2051  }
2052 
2053  ActOnDocumentableDecl(NewTemplate);
2054 
2055  if (SkipBody && SkipBody->ShouldSkip)
2056  return SkipBody->Previous;
2057 
2058  return NewTemplate;
2059 }
2060 
2061 namespace {
2062 /// Tree transform to "extract" a transformed type from a class template's
2063 /// constructor to a deduction guide.
2064 class ExtractTypeForDeductionGuide
2065  : public TreeTransform<ExtractTypeForDeductionGuide> {
2066  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs;
2067 
2068 public:
2070  ExtractTypeForDeductionGuide(
2071  Sema &SemaRef,
2072  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs)
2073  : Base(SemaRef), MaterializedTypedefs(MaterializedTypedefs) {}
2074 
2075  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
2076 
2077  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
2078  ASTContext &Context = SemaRef.getASTContext();
2079  TypedefNameDecl *OrigDecl = TL.getTypedefNameDecl();
2080  TypedefNameDecl *Decl = OrigDecl;
2081  // Transform the underlying type of the typedef and clone the Decl only if
2082  // the typedef has a dependent context.
2083  if (OrigDecl->getDeclContext()->isDependentContext()) {
2084  TypeLocBuilder InnerTLB;
2085  QualType Transformed =
2086  TransformType(InnerTLB, OrigDecl->getTypeSourceInfo()->getTypeLoc());
2087  TypeSourceInfo *TSI = InnerTLB.getTypeSourceInfo(Context, Transformed);
2088  if (isa<TypeAliasDecl>(OrigDecl))
2090  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2091  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2092  else {
2093  assert(isa<TypedefDecl>(OrigDecl) && "Not a Type alias or typedef");
2095  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2096  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2097  }
2098  MaterializedTypedefs.push_back(Decl);
2099  }
2100 
2101  QualType TDTy = Context.getTypedefType(Decl);
2102  TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(TDTy);
2103  TypedefTL.setNameLoc(TL.getNameLoc());
2104 
2105  return TDTy;
2106  }
2107 };
2108 
2109 /// Transform to convert portions of a constructor declaration into the
2110 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
2111 struct ConvertConstructorToDeductionGuideTransform {
2112  ConvertConstructorToDeductionGuideTransform(Sema &S,
2113  ClassTemplateDecl *Template)
2114  : SemaRef(S), Template(Template) {}
2115 
2116  Sema &SemaRef;
2117  ClassTemplateDecl *Template;
2118 
2119  DeclContext *DC = Template->getDeclContext();
2120  CXXRecordDecl *Primary = Template->getTemplatedDecl();
2121  DeclarationName DeductionGuideName =
2123 
2124  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
2125 
2126  // Index adjustment to apply to convert depth-1 template parameters into
2127  // depth-0 template parameters.
2128  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
2129 
2130  /// Transform a constructor declaration into a deduction guide.
2131  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
2132  CXXConstructorDecl *CD) {
2134 
2135  LocalInstantiationScope Scope(SemaRef);
2136 
2137  // C++ [over.match.class.deduct]p1:
2138  // -- For each constructor of the class template designated by the
2139  // template-name, a function template with the following properties:
2140 
2141  // -- The template parameters are the template parameters of the class
2142  // template followed by the template parameters (including default
2143  // template arguments) of the constructor, if any.
2144  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2145  if (FTD) {
2146  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
2147  SmallVector<NamedDecl *, 16> AllParams;
2148  AllParams.reserve(TemplateParams->size() + InnerParams->size());
2149  AllParams.insert(AllParams.begin(),
2150  TemplateParams->begin(), TemplateParams->end());
2151  SubstArgs.reserve(InnerParams->size());
2152 
2153  // Later template parameters could refer to earlier ones, so build up
2154  // a list of substituted template arguments as we go.
2155  for (NamedDecl *Param : *InnerParams) {
2158  Args.addOuterTemplateArguments(SubstArgs);
2159  Args.addOuterRetainedLevel();
2160  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
2161  if (!NewParam)
2162  return nullptr;
2163  AllParams.push_back(NewParam);
2164  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
2165  SemaRef.Context.getInjectedTemplateArg(NewParam)));
2166  }
2167  TemplateParams = TemplateParameterList::Create(
2168  SemaRef.Context, InnerParams->getTemplateLoc(),
2169  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
2170  /*FIXME: RequiresClause*/ nullptr);
2171  }
2172 
2173  // If we built a new template-parameter-list, track that we need to
2174  // substitute references to the old parameters into references to the
2175  // new ones.
2178  if (FTD) {
2179  Args.addOuterTemplateArguments(SubstArgs);
2180  Args.addOuterRetainedLevel();
2181  }
2182 
2185  assert(FPTL && "no prototype for constructor declaration");
2186 
2187  // Transform the type of the function, adjusting the return type and
2188  // replacing references to the old parameters with references to the
2189  // new ones.
2190  TypeLocBuilder TLB;
2192  SmallVector<TypedefNameDecl *, 4> MaterializedTypedefs;
2193  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args,
2194  MaterializedTypedefs);
2195  if (NewType.isNull())
2196  return nullptr;
2197  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
2198 
2199  return buildDeductionGuide(TemplateParams, CD->getExplicitSpecifier(),
2200  NewTInfo, CD->getBeginLoc(), CD->getLocation(),
2201  CD->getEndLoc(), MaterializedTypedefs);
2202  }
2203 
2204  /// Build a deduction guide with the specified parameter types.
2205  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
2206  SourceLocation Loc = Template->getLocation();
2207 
2208  // Build the requested type.
2210  EPI.HasTrailingReturn = true;
2211  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
2212  DeductionGuideName, EPI);
2213  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
2214 
2215  FunctionProtoTypeLoc FPTL =
2217 
2218  // Build the parameters, needed during deduction / substitution.
2220  for (auto T : ParamTypes) {
2221  ParmVarDecl *NewParam = ParmVarDecl::Create(
2222  SemaRef.Context, DC, Loc, Loc, nullptr, T,
2223  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
2224  NewParam->setScopeInfo(0, Params.size());
2225  FPTL.setParam(Params.size(), NewParam);
2226  Params.push_back(NewParam);
2227  }
2228 
2229  return buildDeductionGuide(Template->getTemplateParameters(),
2230  ExplicitSpecifier(), TSI, Loc, Loc, Loc);
2231  }
2232 
2233 private:
2234  /// Transform a constructor template parameter into a deduction guide template
2235  /// parameter, rebuilding any internal references to earlier parameters and
2236  /// renumbering as we go.
2237  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
2239  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
2240  // TemplateTypeParmDecl's index cannot be changed after creation, so
2241  // substitute it directly.
2242  auto *NewTTP = TemplateTypeParmDecl::Create(
2243  SemaRef.Context, DC, TTP->getBeginLoc(), TTP->getLocation(),
2244  /*Depth*/ 0, Depth1IndexAdjustment + TTP->getIndex(),
2245  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
2246  TTP->isParameterPack(), TTP->hasTypeConstraint(),
2247  TTP->isExpandedParameterPack() ?
2248  llvm::Optional<unsigned>(TTP->getNumExpansionParameters()) : None);
2249  if (const auto *TC = TTP->getTypeConstraint()) {
2250  TemplateArgumentListInfo TransformedArgs;
2251  const auto *ArgsAsWritten = TC->getTemplateArgsAsWritten();
2252  if (!ArgsAsWritten ||
2253  SemaRef.Subst(ArgsAsWritten->getTemplateArgs(),
2254  ArgsAsWritten->NumTemplateArgs, TransformedArgs,
2255  Args))
2256  SemaRef.AttachTypeConstraint(
2257  TC->getNestedNameSpecifierLoc(), TC->getConceptNameInfo(),
2258  TC->getNamedConcept(), ArgsAsWritten ? &TransformedArgs : nullptr,
2259  NewTTP,
2260  NewTTP->isParameterPack()
2261  ? cast<CXXFoldExpr>(TC->getImmediatelyDeclaredConstraint())
2262  ->getEllipsisLoc()
2263  : SourceLocation());
2264  }
2265  if (TTP->hasDefaultArgument()) {
2266  TypeSourceInfo *InstantiatedDefaultArg =
2267  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
2268  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
2269  if (InstantiatedDefaultArg)
2270  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
2271  }
2272  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
2273  NewTTP);
2274  return NewTTP;
2275  }
2276 
2277  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
2278  return transformTemplateParameterImpl(TTP, Args);
2279 
2280  return transformTemplateParameterImpl(
2281  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
2282  }
2283  template<typename TemplateParmDecl>
2284  TemplateParmDecl *
2285  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
2287  // Ask the template instantiator to do the heavy lifting for us, then adjust
2288  // the index of the parameter once it's done.
2289  auto *NewParam =
2290  cast<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
2291  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
2292  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
2293  return NewParam;
2294  }
2295 
2296  QualType transformFunctionProtoType(
2300  SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2301  SmallVector<QualType, 4> ParamTypes;
2302  const FunctionProtoType *T = TL.getTypePtr();
2303 
2304  // -- The types of the function parameters are those of the constructor.
2305  for (auto *OldParam : TL.getParams()) {
2306  ParmVarDecl *NewParam =
2307  transformFunctionTypeParam(OldParam, Args, MaterializedTypedefs);
2308  if (!NewParam)
2309  return QualType();
2310  ParamTypes.push_back(NewParam->getType());
2311  Params.push_back(NewParam);
2312  }
2313 
2314  // -- The return type is the class template specialization designated by
2315  // the template-name and template arguments corresponding to the
2316  // template parameters obtained from the class template.
2317  //
2318  // We use the injected-class-name type of the primary template instead.
2319  // This has the convenient property that it is different from any type that
2320  // the user can write in a deduction-guide (because they cannot enter the
2321  // context of the template), so implicit deduction guides can never collide
2322  // with explicit ones.
2323  QualType ReturnType = DeducedType;
2324  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
2325 
2326  // Resolving a wording defect, we also inherit the variadicness of the
2327  // constructor.
2329  EPI.Variadic = T->isVariadic();
2330  EPI.HasTrailingReturn = true;
2331 
2332  QualType Result = SemaRef.BuildFunctionType(
2333  ReturnType, ParamTypes, TL.getBeginLoc(), DeductionGuideName, EPI);
2334  if (Result.isNull())
2335  return QualType();
2336 
2337  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
2339  NewTL.setLParenLoc(TL.getLParenLoc());
2340  NewTL.setRParenLoc(TL.getRParenLoc());
2342  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
2343  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
2344  NewTL.setParam(I, Params[I]);
2345 
2346  return Result;
2347  }
2348 
2349  ParmVarDecl *transformFunctionTypeParam(
2351  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2352  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
2353  TypeSourceInfo *NewDI;
2354  if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
2355  // Expand out the one and only element in each inner pack.
2356  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
2357  NewDI =
2358  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
2359  OldParam->getLocation(), OldParam->getDeclName());
2360  if (!NewDI) return nullptr;
2361  NewDI =
2362  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
2363  PackTL.getTypePtr()->getNumExpansions());
2364  } else
2365  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
2366  OldParam->getDeclName());
2367  if (!NewDI)
2368  return nullptr;
2369 
2370  // Extract the type. This (for instance) replaces references to typedef
2371  // members of the current instantiations with the definitions of those
2372  // typedefs, avoiding triggering instantiation of the deduced type during
2373  // deduction.
2374  NewDI = ExtractTypeForDeductionGuide(SemaRef, MaterializedTypedefs)
2375  .transform(NewDI);
2376 
2377  // Resolving a wording defect, we also inherit default arguments from the
2378  // constructor.
2379  ExprResult NewDefArg;
2380  if (OldParam->hasDefaultArg()) {
2381  // We don't care what the value is (we won't use it); just create a
2382  // placeholder to indicate there is a default argument.
2383  QualType ParamTy = NewDI->getType();
2384  NewDefArg = new (SemaRef.Context)
2385  OpaqueValueExpr(OldParam->getDefaultArg()->getBeginLoc(),
2386  ParamTy.getNonLValueExprType(SemaRef.Context),
2387  ParamTy->isLValueReferenceType() ? VK_LValue :
2388  ParamTy->isRValueReferenceType() ? VK_XValue :
2389  VK_RValue);
2390  }
2391 
2392  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
2393  OldParam->getInnerLocStart(),
2394  OldParam->getLocation(),
2395  OldParam->getIdentifier(),
2396  NewDI->getType(),
2397  NewDI,
2398  OldParam->getStorageClass(),
2399  NewDefArg.get());
2400  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
2401  OldParam->getFunctionScopeIndex());
2402  SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
2403  return NewParam;
2404  }
2405 
2406  FunctionTemplateDecl *buildDeductionGuide(
2407  TemplateParameterList *TemplateParams, ExplicitSpecifier ES,
2408  TypeSourceInfo *TInfo, SourceLocation LocStart, SourceLocation Loc,
2409  SourceLocation LocEnd,
2410  llvm::ArrayRef<TypedefNameDecl *> MaterializedTypedefs = {}) {
2411  DeclarationNameInfo Name(DeductionGuideName, Loc);
2412  ArrayRef<ParmVarDecl *> Params =
2413  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
2414 
2415  // Build the implicit deduction guide template.
2416  auto *Guide =
2417  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, ES, Name,
2418  TInfo->getType(), TInfo, LocEnd);
2419  Guide->setImplicit();
2420  Guide->setParams(Params);
2421 
2422  for (auto *Param : Params)
2423  Param->setDeclContext(Guide);
2424  for (auto *TD : MaterializedTypedefs)
2425  TD->setDeclContext(Guide);
2426 
2427  auto *GuideTemplate = FunctionTemplateDecl::Create(
2428  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
2429  GuideTemplate->setImplicit();
2430  Guide->setDescribedFunctionTemplate(GuideTemplate);
2431 
2432  if (isa<CXXRecordDecl>(DC)) {
2433  Guide->setAccess(AS_public);
2434  GuideTemplate->setAccess(AS_public);
2435  }
2436 
2437  DC->addDecl(GuideTemplate);
2438  return GuideTemplate;
2439  }
2440 };
2441 }
2442 
2444  SourceLocation Loc) {
2445  if (CXXRecordDecl *DefRecord =
2446  cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
2447  TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
2448  Template = DescribedTemplate ? DescribedTemplate : Template;
2449  }
2450 
2451  DeclContext *DC = Template->getDeclContext();
2452  if (DC->isDependentContext())
2453  return;
2454 
2455  ConvertConstructorToDeductionGuideTransform Transform(
2456  *this, cast<ClassTemplateDecl>(Template));
2457  if (!isCompleteType(Loc, Transform.DeducedType))
2458  return;
2459 
2460  // Check whether we've already declared deduction guides for this template.
2461  // FIXME: Consider storing a flag on the template to indicate this.
2462  auto Existing = DC->lookup(Transform.DeductionGuideName);
2463  for (auto *D : Existing)
2464  if (D->isImplicit())
2465  return;
2466 
2467  // In case we were expanding a pack when we attempted to declare deduction
2468  // guides, turn off pack expansion for everything we're about to do.
2469  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
2470  // Create a template instantiation record to track the "instantiation" of
2471  // constructors into deduction guides.
2472  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
2473  // this substitution process actually fail?
2474  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
2475  if (BuildingDeductionGuides.isInvalid())
2476  return;
2477 
2478  // Convert declared constructors into deduction guide templates.
2479  // FIXME: Skip constructors for which deduction must necessarily fail (those
2480  // for which some class template parameter without a default argument never
2481  // appears in a deduced context).
2482  bool AddedAny = false;
2483  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2484  D = D->getUnderlyingDecl();
2485  if (D->isInvalidDecl() || D->isImplicit())
2486  continue;
2487  D = cast<NamedDecl>(D->getCanonicalDecl());
2488 
2489  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2490  auto *CD =
2491  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2492  // Class-scope explicit specializations (MS extension) do not result in
2493  // deduction guides.
2494  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2495  continue;
2496 
2497  Transform.transformConstructor(FTD, CD);
2498  AddedAny = true;
2499  }
2500 
2501  // C++17 [over.match.class.deduct]
2502  // -- If C is not defined or does not declare any constructors, an
2503  // additional function template derived as above from a hypothetical
2504  // constructor C().
2505  if (!AddedAny)
2506  Transform.buildSimpleDeductionGuide(None);
2507 
2508  // -- An additional function template derived as above from a hypothetical
2509  // constructor C(C), called the copy deduction candidate.
2510  cast<CXXDeductionGuideDecl>(
2511  cast<FunctionTemplateDecl>(
2512  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2513  ->getTemplatedDecl())
2514  ->setIsCopyDeductionCandidate();
2515 }
2516 
2517 /// Diagnose the presence of a default template argument on a
2518 /// template parameter, which is ill-formed in certain contexts.
2519 ///
2520 /// \returns true if the default template argument should be dropped.
2523  SourceLocation ParamLoc,
2524  SourceRange DefArgRange) {
2525  switch (TPC) {
2527  case Sema::TPC_VarTemplate:
2529  return false;
2530 
2533  // C++ [temp.param]p9:
2534  // A default template-argument shall not be specified in a
2535  // function template declaration or a function template
2536  // definition [...]
2537  // If a friend function template declaration specifies a default
2538  // template-argument, that declaration shall be a definition and shall be
2539  // the only declaration of the function template in the translation unit.
2540  // (C++98/03 doesn't have this wording; see DR226).
2541  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2542  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2543  : diag::ext_template_parameter_default_in_function_template)
2544  << DefArgRange;
2545  return false;
2546 
2548  // C++0x [temp.param]p9:
2549  // A default template-argument shall not be specified in the
2550  // template-parameter-lists of the definition of a member of a
2551  // class template that appears outside of the member's class.
2552  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2553  << DefArgRange;
2554  return true;
2555 
2558  // C++ [temp.param]p9:
2559  // A default template-argument shall not be specified in a
2560  // friend template declaration.
2561  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2562  << DefArgRange;
2563  return true;
2564 
2565  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2566  // for friend function templates if there is only a single
2567  // declaration (and it is a definition). Strange!
2568  }
2569 
2570  llvm_unreachable("Invalid TemplateParamListContext!");
2571 }
2572 
2573 /// Check for unexpanded parameter packs within the template parameters
2574 /// of a template template parameter, recursively.
2576  TemplateTemplateParmDecl *TTP) {
2577  // A template template parameter which is a parameter pack is also a pack
2578  // expansion.
2579  if (TTP->isParameterPack())
2580  return false;
2581 
2583  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2584  NamedDecl *P = Params->getParam(I);
2585  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(P)) {
2586  if (!TTP->isParameterPack())
2587  if (const TypeConstraint *TC = TTP->getTypeConstraint())
2588  if (TC->hasExplicitTemplateArgs())
2589  for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
2590  if (S.DiagnoseUnexpandedParameterPack(ArgLoc,
2592  return true;
2593  continue;
2594  }
2595 
2596  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2597  if (!NTTP->isParameterPack() &&
2598  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2599  NTTP->getTypeSourceInfo(),
2601  return true;
2602 
2603  continue;
2604  }
2605 
2606  if (TemplateTemplateParmDecl *InnerTTP
2607  = dyn_cast<TemplateTemplateParmDecl>(P))
2608  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2609  return true;
2610  }
2611 
2612  return false;
2613 }
2614 
2615 /// Checks the validity of a template parameter list, possibly
2616 /// considering the template parameter list from a previous
2617 /// declaration.
2618 ///
2619 /// If an "old" template parameter list is provided, it must be
2620 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2621 /// template parameter list.
2622 ///
2623 /// \param NewParams Template parameter list for a new template
2624 /// declaration. This template parameter list will be updated with any
2625 /// default arguments that are carried through from the previous
2626 /// template parameter list.
2627 ///
2628 /// \param OldParams If provided, template parameter list from a
2629 /// previous declaration of the same template. Default template
2630 /// arguments will be merged from the old template parameter list to
2631 /// the new template parameter list.
2632 ///
2633 /// \param TPC Describes the context in which we are checking the given
2634 /// template parameter list.
2635 ///
2636 /// \param SkipBody If we might have already made a prior merged definition
2637 /// of this template visible, the corresponding body-skipping information.
2638 /// Default argument redefinition is not an error when skipping such a body,
2639 /// because (under the ODR) we can assume the default arguments are the same
2640 /// as the prior merged definition.
2641 ///
2642 /// \returns true if an error occurred, false otherwise.
2644  TemplateParameterList *OldParams,
2646  SkipBodyInfo *SkipBody) {
2647  bool Invalid = false;
2648 
2649  // C++ [temp.param]p10:
2650  // The set of default template-arguments available for use with a
2651  // template declaration or definition is obtained by merging the
2652  // default arguments from the definition (if in scope) and all
2653  // declarations in scope in the same way default function
2654  // arguments are (8.3.6).
2655  bool SawDefaultArgument = false;
2656  SourceLocation PreviousDefaultArgLoc;
2657 
2658  // Dummy initialization to avoid warnings.
2659  TemplateParameterList::iterator OldParam = NewParams->end();
2660  if (OldParams)
2661  OldParam = OldParams->begin();
2662 
2663  bool RemoveDefaultArguments = false;
2664  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2665  NewParamEnd = NewParams->end();
2666  NewParam != NewParamEnd; ++NewParam) {
2667  // Variables used to diagnose redundant default arguments
2668  bool RedundantDefaultArg = false;
2669  SourceLocation OldDefaultLoc;
2670  SourceLocation NewDefaultLoc;
2671 
2672  // Variable used to diagnose missing default arguments
2673  bool MissingDefaultArg = false;
2674 
2675  // Variable used to diagnose non-final parameter packs
2676  bool SawParameterPack = false;
2677 
2678  if (TemplateTypeParmDecl *NewTypeParm
2679  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2680  // Check the presence of a default argument here.
2681  if (NewTypeParm->hasDefaultArgument() &&
2683  NewTypeParm->getLocation(),
2684  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2685  .getSourceRange()))
2686  NewTypeParm->removeDefaultArgument();
2687 
2688  // Merge default arguments for template type parameters.
2689  TemplateTypeParmDecl *OldTypeParm
2690  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2691  if (NewTypeParm->isParameterPack()) {
2692  assert(!NewTypeParm->hasDefaultArgument() &&
2693  "Parameter packs can't have a default argument!");
2694  SawParameterPack = true;
2695  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2696  NewTypeParm->hasDefaultArgument() &&
2697  (!SkipBody || !SkipBody->ShouldSkip)) {
2698  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2699  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2700  SawDefaultArgument = true;
2701  RedundantDefaultArg = true;
2702  PreviousDefaultArgLoc = NewDefaultLoc;
2703  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2704  // Merge the default argument from the old declaration to the
2705  // new declaration.
2706  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2707  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2708  } else if (NewTypeParm->hasDefaultArgument()) {
2709  SawDefaultArgument = true;
2710  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2711  } else if (SawDefaultArgument)
2712  MissingDefaultArg = true;
2713  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2714  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2715  // Check for unexpanded parameter packs.
2716  if (!NewNonTypeParm->isParameterPack() &&
2717  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2718  NewNonTypeParm->getTypeSourceInfo(),
2719  UPPC_NonTypeTemplateParameterType)) {
2720  Invalid = true;
2721  continue;
2722  }
2723 
2724  // Check the presence of a default argument here.
2725  if (NewNonTypeParm->hasDefaultArgument() &&
2727  NewNonTypeParm->getLocation(),
2728  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2729  NewNonTypeParm->removeDefaultArgument();
2730  }
2731 
2732  // Merge default arguments for non-type template parameters
2733  NonTypeTemplateParmDecl *OldNonTypeParm
2734  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2735  if (NewNonTypeParm->isParameterPack()) {
2736  assert(!NewNonTypeParm->hasDefaultArgument() &&
2737  "Parameter packs can't have a default argument!");
2738  if (!NewNonTypeParm->isPackExpansion())
2739  SawParameterPack = true;
2740  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2741  NewNonTypeParm->hasDefaultArgument() &&
2742  (!SkipBody || !SkipBody->ShouldSkip)) {
2743  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2744  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2745  SawDefaultArgument = true;
2746  RedundantDefaultArg = true;
2747  PreviousDefaultArgLoc = NewDefaultLoc;
2748  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2749  // Merge the default argument from the old declaration to the
2750  // new declaration.
2751  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2752  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2753  } else if (NewNonTypeParm->hasDefaultArgument()) {
2754  SawDefaultArgument = true;
2755  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2756  } else if (SawDefaultArgument)
2757  MissingDefaultArg = true;
2758  } else {
2759  TemplateTemplateParmDecl *NewTemplateParm
2760  = cast<TemplateTemplateParmDecl>(*NewParam);
2761 
2762  // Check for unexpanded parameter packs, recursively.
2763  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2764  Invalid = true;
2765  continue;
2766  }
2767 
2768  // Check the presence of a default argument here.
2769  if (NewTemplateParm->hasDefaultArgument() &&
2771  NewTemplateParm->getLocation(),
2772  NewTemplateParm->getDefaultArgument().getSourceRange()))
2773  NewTemplateParm->removeDefaultArgument();
2774 
2775  // Merge default arguments for template template parameters
2776  TemplateTemplateParmDecl *OldTemplateParm
2777  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2778  if (NewTemplateParm->isParameterPack()) {
2779  assert(!NewTemplateParm->hasDefaultArgument() &&
2780  "Parameter packs can't have a default argument!");
2781  if (!NewTemplateParm->isPackExpansion())
2782  SawParameterPack = true;
2783  } else if (OldTemplateParm &&
2784  hasVisibleDefaultArgument(OldTemplateParm) &&
2785  NewTemplateParm->hasDefaultArgument() &&
2786  (!SkipBody || !SkipBody->ShouldSkip)) {
2787  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2788  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2789  SawDefaultArgument = true;
2790  RedundantDefaultArg = true;
2791  PreviousDefaultArgLoc = NewDefaultLoc;
2792  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2793  // Merge the default argument from the old declaration to the
2794  // new declaration.
2795  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2796  PreviousDefaultArgLoc
2797  = OldTemplateParm->getDefaultArgument().getLocation();
2798  } else if (NewTemplateParm->hasDefaultArgument()) {
2799  SawDefaultArgument = true;
2800  PreviousDefaultArgLoc
2801  = NewTemplateParm->getDefaultArgument().getLocation();
2802  } else if (SawDefaultArgument)
2803  MissingDefaultArg = true;
2804  }
2805 
2806  // C++11 [temp.param]p11:
2807  // If a template parameter of a primary class template or alias template
2808  // is a template parameter pack, it shall be the last template parameter.
2809  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2810  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2811  TPC == TPC_TypeAliasTemplate)) {
2812  Diag((*NewParam)->getLocation(),
2813  diag::err_template_param_pack_must_be_last_template_parameter);
2814  Invalid = true;
2815  }
2816 
2817  if (RedundantDefaultArg) {
2818  // C++ [temp.param]p12:
2819  // A template-parameter shall not be given default arguments
2820  // by two different declarations in the same scope.
2821  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2822  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2823  Invalid = true;
2824  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2825  // C++ [temp.param]p11:
2826  // If a template-parameter of a class template has a default
2827  // template-argument, each subsequent template-parameter shall either
2828  // have a default template-argument supplied or be a template parameter
2829  // pack.
2830  Diag((*NewParam)->getLocation(),
2831  diag::err_template_param_default_arg_missing);
2832  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2833  Invalid = true;
2834  RemoveDefaultArguments = true;
2835  }
2836 
2837  // If we have an old template parameter list that we're merging
2838  // in, move on to the next parameter.
2839  if (OldParams)
2840  ++OldParam;
2841  }
2842 
2843  // We were missing some default arguments at the end of the list, so remove
2844  // all of the default arguments.
2845  if (RemoveDefaultArguments) {
2846  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2847  NewParamEnd = NewParams->end();
2848  NewParam != NewParamEnd; ++NewParam) {
2849  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2850  TTP->removeDefaultArgument();
2851  else if (NonTypeTemplateParmDecl *NTTP
2852  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2853  NTTP->removeDefaultArgument();
2854  else
2855  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2856  }
2857  }
2858 
2859  return Invalid;
2860 }
2861 
2862 namespace {
2863 
2864 /// A class which looks for a use of a certain level of template
2865 /// parameter.
2866 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2868 
2869  unsigned Depth;
2870 
2871  // Whether we're looking for a use of a template parameter that makes the
2872  // overall construct type-dependent / a dependent type. This is strictly
2873  // best-effort for now; we may fail to match at all for a dependent type
2874  // in some cases if this is set.
2875  bool IgnoreNonTypeDependent;
2876 
2877  bool Match;
2878  SourceLocation MatchLoc;
2879 
2880  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2881  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2882  Match(false) {}
2883 
2884  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2885  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2886  NamedDecl *ND = Params->getParam(0);
2887  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2888  Depth = PD->getDepth();
2889  } else if (NonTypeTemplateParmDecl *PD =
2890  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2891  Depth = PD->getDepth();
2892  } else {
2893  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2894  }
2895  }
2896 
2897  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2898  if (ParmDepth >= Depth) {
2899  Match = true;
2900  MatchLoc = Loc;
2901  return true;
2902  }
2903  return false;
2904  }
2905 
2906  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2907  // Prune out non-type-dependent expressions if requested. This can
2908  // sometimes result in us failing to find a template parameter reference
2909  // (if a value-dependent expression creates a dependent type), but this
2910  // mode is best-effort only.
2911  if (auto *E = dyn_cast_or_null<Expr>(S))
2912  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2913  return true;
2914  return super::TraverseStmt(S, Q);
2915  }
2916 
2917  bool TraverseTypeLoc(TypeLoc TL) {
2918  if (IgnoreNonTypeDependent && !TL.isNull() &&
2919  !TL.getType()->isDependentType())
2920  return true;
2921  return super::TraverseTypeLoc(TL);
2922  }
2923 
2924  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2925  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2926  }
2927 
2928  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2929  // For a best-effort search, keep looking until we find a location.
2930  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2931  }
2932 
2933  bool TraverseTemplateName(TemplateName N) {
2934  if (TemplateTemplateParmDecl *PD =
2935  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2936  if (Matches(PD->getDepth()))
2937  return false;
2938  return super::TraverseTemplateName(N);
2939  }
2940 
2941  bool VisitDeclRefExpr(DeclRefExpr *E) {
2942  if (NonTypeTemplateParmDecl *PD =
2943  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2944  if (Matches(PD->getDepth(), E->getExprLoc()))
2945  return false;
2946  return super::VisitDeclRefExpr(E);
2947  }
2948 
2949  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2950  return TraverseType(T->getReplacementType());
2951  }
2952 
2953  bool
2954  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2955  return TraverseTemplateArgument(T->getArgumentPack());
2956  }
2957 
2958  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2959  return TraverseType(T->getInjectedSpecializationType());
2960  }
2961 };
2962 } // end anonymous namespace
2963 
2964 /// Determines whether a given type depends on the given parameter
2965 /// list.
2966 static bool
2968  if (!Params->size())
2969  return false;
2970 
2971  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2972  Checker.TraverseType(T);
2973  return Checker.Match;
2974 }
2975 
2976 // Find the source range corresponding to the named type in the given
2977 // nested-name-specifier, if any.
2979  QualType T,
2980  const CXXScopeSpec &SS) {
2982  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2983  if (const Type *CurType = NNS->getAsType()) {
2984  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2985  return NNSLoc.getTypeLoc().getSourceRange();
2986  } else
2987  break;
2988 
2989  NNSLoc = NNSLoc.getPrefix();
2990  }
2991 
2992  return SourceRange();
2993 }
2994 
2995 /// Match the given template parameter lists to the given scope
2996 /// specifier, returning the template parameter list that applies to the
2997 /// name.
2998 ///
2999 /// \param DeclStartLoc the start of the declaration that has a scope
3000 /// specifier or a template parameter list.
3001 ///
3002 /// \param DeclLoc The location of the declaration itself.
3003 ///
3004 /// \param SS the scope specifier that will be matched to the given template
3005 /// parameter lists. This scope specifier precedes a qualified name that is
3006 /// being declared.
3007 ///
3008 /// \param TemplateId The template-id following the scope specifier, if there
3009 /// is one. Used to check for a missing 'template<>'.
3010 ///
3011 /// \param ParamLists the template parameter lists, from the outermost to the
3012 /// innermost template parameter lists.
3013 ///
3014 /// \param IsFriend Whether to apply the slightly different rules for
3015 /// matching template parameters to scope specifiers in friend
3016 /// declarations.
3017 ///
3018 /// \param IsMemberSpecialization will be set true if the scope specifier
3019 /// denotes a fully-specialized type, and therefore this is a declaration of
3020 /// a member specialization.
3021 ///
3022 /// \returns the template parameter list, if any, that corresponds to the
3023 /// name that is preceded by the scope specifier @p SS. This template
3024 /// parameter list may have template parameters (if we're declaring a
3025 /// template) or may have no template parameters (if we're declaring a
3026 /// template specialization), or may be NULL (if what we're declaring isn't
3027 /// itself a template).
3029  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
3030  TemplateIdAnnotation *TemplateId,
3031  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
3032  bool &IsMemberSpecialization, bool &Invalid, bool SuppressDiagnostic) {
3033  IsMemberSpecialization = false;
3034  Invalid = false;
3035 
3036  // The sequence of nested types to which we will match up the template
3037  // parameter lists. We first build this list by starting with the type named
3038  // by the nested-name-specifier and walking out until we run out of types.
3039  SmallVector<QualType, 4> NestedTypes;
3040  QualType T;
3041  if (SS.getScopeRep()) {
3042  if (CXXRecordDecl *Record
3043  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
3044  T = Context.getTypeDeclType(Record);
3045  else
3046  T = QualType(SS.getScopeRep()->getAsType(), 0);
3047  }
3048 
3049  // If we found an explicit specialization that prevents us from needing
3050  // 'template<>' headers, this will be set to the location of that
3051  // explicit specialization.
3052  SourceLocation ExplicitSpecLoc;
3053 
3054  while (!T.isNull()) {
3055  NestedTypes.push_back(T);
3056 
3057  // Retrieve the parent of a record type.
3058  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3059  // If this type is an explicit specialization, we're done.
3061  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3062  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
3063  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
3064  ExplicitSpecLoc = Spec->getLocation();
3065  break;
3066  }
3067  } else if (Record->getTemplateSpecializationKind()
3069  ExplicitSpecLoc = Record->getLocation();
3070  break;
3071  }
3072 
3073  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
3074  T = Context.getTypeDeclType(Parent);
3075  else
3076  T = QualType();
3077  continue;
3078  }
3079 
3080  if (const TemplateSpecializationType *TST
3082  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3083  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
3084  T = Context.getTypeDeclType(Parent);
3085  else
3086  T = QualType();
3087  continue;
3088  }
3089  }
3090 
3091  // Look one step prior in a dependent template specialization type.
3092  if (const DependentTemplateSpecializationType *DependentTST
3094  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
3095  T = QualType(NNS->getAsType(), 0);
3096  else
3097  T = QualType();
3098  continue;
3099  }
3100 
3101  // Look one step prior in a dependent name type.
3102  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
3103  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
3104  T = QualType(NNS->getAsType(), 0);
3105  else
3106  T = QualType();
3107  continue;
3108  }
3109 
3110  // Retrieve the parent of an enumeration type.
3111  if (const EnumType *EnumT = T->getAs<EnumType>()) {
3112  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
3113  // check here.
3114  EnumDecl *Enum = EnumT->getDecl();
3115 
3116  // Get to the parent type.
3117  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
3118  T = Context.getTypeDeclType(Parent);
3119  else
3120  T = QualType();
3121  continue;
3122  }
3123 
3124  T = QualType();
3125  }
3126  // Reverse the nested types list, since we want to traverse from the outermost
3127  // to the innermost while checking template-parameter-lists.
3128  std::reverse(NestedTypes.begin(), NestedTypes.end());
3129 
3130  // C++0x [temp.expl.spec]p17:
3131  // A member or a member template may be nested within many
3132  // enclosing class templates. In an explicit specialization for
3133  // such a member, the member declaration shall be preceded by a
3134  // template<> for each enclosing class template that is
3135  // explicitly specialized.
3136  bool SawNonEmptyTemplateParameterList = false;
3137 
3138  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
3139  if (SawNonEmptyTemplateParameterList) {
3140  if (!SuppressDiagnostic)
3141  Diag(DeclLoc, diag::err_specialize_member_of_template)
3142  << !Recovery << Range;
3143  Invalid = true;
3144  IsMemberSpecialization = false;
3145  return true;
3146  }
3147 
3148  return false;
3149  };
3150 
3151  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
3152  // Check that we can have an explicit specialization here.
3153  if (CheckExplicitSpecialization(Range, true))
3154  return true;
3155 
3156  // We don't have a template header, but we should.
3157  SourceLocation ExpectedTemplateLoc;
3158  if (!ParamLists.empty())
3159  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
3160  else
3161  ExpectedTemplateLoc = DeclStartLoc;
3162 
3163  if (!SuppressDiagnostic)
3164  Diag(DeclLoc, diag::err_template_spec_needs_header)
3165  << Range
3166  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
3167  return false;
3168  };
3169 
3170  unsigned ParamIdx = 0;
3171  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
3172  ++TypeIdx) {
3173  T = NestedTypes[TypeIdx];
3174 
3175  // Whether we expect a 'template<>' header.
3176  bool NeedEmptyTemplateHeader = false;
3177 
3178  // Whether we expect a template header with parameters.
3179  bool NeedNonemptyTemplateHeader = false;
3180 
3181  // For a dependent type, the set of template parameters that we
3182  // expect to see.
3183  TemplateParameterList *ExpectedTemplateParams = nullptr;
3184 
3185  // C++0x [temp.expl.spec]p15:
3186  // A member or a member template may be nested within many enclosing
3187  // class templates. In an explicit specialization for such a member, the
3188  // member declaration shall be preceded by a template<> for each
3189  // enclosing class template that is explicitly specialized.
3190  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3192  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
3193  ExpectedTemplateParams = Partial->getTemplateParameters();
3194  NeedNonemptyTemplateHeader = true;
3195  } else if (Record->isDependentType()) {
3196  if (Record->getDescribedClassTemplate()) {
3197  ExpectedTemplateParams = Record->getDescribedClassTemplate()
3198  ->getTemplateParameters();
3199  NeedNonemptyTemplateHeader = true;
3200  }
3201  } else if (ClassTemplateSpecializationDecl *Spec
3202  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3203  // C++0x [temp.expl.spec]p4:
3204  // Members of an explicitly specialized class template are defined
3205  // in the same manner as members of normal classes, and not using
3206  // the template<> syntax.
3207  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
3208  NeedEmptyTemplateHeader = true;
3209  else
3210  continue;
3211  } else if (Record->getTemplateSpecializationKind()) {
3212  if (Record->getTemplateSpecializationKind()
3214  TypeIdx == NumTypes - 1)
3215  IsMemberSpecialization = true;
3216 
3217  continue;
3218  }
3219  } else if (const TemplateSpecializationType *TST
3221  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3222  ExpectedTemplateParams = Template->getTemplateParameters();
3223  NeedNonemptyTemplateHeader = true;
3224  }
3225  } else if (T->getAs<DependentTemplateSpecializationType>()) {
3226  // FIXME: We actually could/should check the template arguments here
3227  // against the corresponding template parameter list.
3228  NeedNonemptyTemplateHeader = false;
3229  }
3230 
3231  // C++ [temp.expl.spec]p16:
3232  // In an explicit specialization declaration for a member of a class
3233  // template or a member template that ap- pears in namespace scope, the
3234  // member template and some of its enclosing class templates may remain
3235  // unspecialized, except that the declaration shall not explicitly
3236  // specialize a class member template if its en- closing class templates
3237  // are not explicitly specialized as well.
3238  if (ParamIdx < ParamLists.size()) {
3239  if (ParamLists[ParamIdx]->size() == 0) {
3240  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3241  false))
3242  return nullptr;
3243  } else
3244  SawNonEmptyTemplateParameterList = true;
3245  }
3246 
3247  if (NeedEmptyTemplateHeader) {
3248  // If we're on the last of the types, and we need a 'template<>' header
3249  // here, then it's a member specialization.
3250  if (TypeIdx == NumTypes - 1)
3251  IsMemberSpecialization = true;
3252 
3253  if (ParamIdx < ParamLists.size()) {
3254  if (ParamLists[ParamIdx]->size() > 0) {
3255  // The header has template parameters when it shouldn't. Complain.
3256  if (!SuppressDiagnostic)
3257  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3258  diag::err_template_param_list_matches_nontemplate)
3259  << T
3260  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
3261  ParamLists[ParamIdx]->getRAngleLoc())
3262  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3263  Invalid = true;
3264  return nullptr;
3265  }
3266 
3267  // Consume this template header.
3268  ++ParamIdx;
3269  continue;
3270  }
3271 
3272  if (!IsFriend)
3273  if (DiagnoseMissingExplicitSpecialization(
3274  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
3275  return nullptr;
3276 
3277  continue;
3278  }
3279 
3280  if (NeedNonemptyTemplateHeader) {
3281  // In friend declarations we can have template-ids which don't
3282  // depend on the corresponding template parameter lists. But
3283  // assume that empty parameter lists are supposed to match this
3284  // template-id.
3285  if (IsFriend && T->isDependentType()) {
3286  if (ParamIdx < ParamLists.size() &&
3287  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
3288  ExpectedTemplateParams = nullptr;
3289  else
3290  continue;
3291  }
3292 
3293  if (ParamIdx < ParamLists.size()) {
3294  // Check the template parameter list, if we can.
3295  if (ExpectedTemplateParams &&
3296  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
3297  ExpectedTemplateParams,
3298  !SuppressDiagnostic, TPL_TemplateMatch))
3299  Invalid = true;
3300 
3301  if (!Invalid &&
3302  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
3303  TPC_ClassTemplateMember))
3304  Invalid = true;
3305 
3306  ++ParamIdx;
3307  continue;
3308  }
3309 
3310  if (!SuppressDiagnostic)
3311  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
3312  << T
3313  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3314  Invalid = true;
3315  continue;
3316  }
3317  }
3318 
3319  // If there were at least as many template-ids as there were template
3320  // parameter lists, then there are no template parameter lists remaining for
3321  // the declaration itself.
3322  if (ParamIdx >= ParamLists.size()) {
3323  if (TemplateId && !IsFriend) {
3324  // We don't have a template header for the declaration itself, but we
3325  // should.
3326  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
3327  TemplateId->RAngleLoc));
3328 
3329  // Fabricate an empty template parameter list for the invented header.
3331  SourceLocation(), None,
3332  SourceLocation(), nullptr);
3333  }
3334 
3335  return nullptr;
3336  }
3337 
3338  // If there were too many template parameter lists, complain about that now.
3339  if (ParamIdx < ParamLists.size() - 1) {
3340  bool HasAnyExplicitSpecHeader = false;
3341  bool AllExplicitSpecHeaders = true;
3342  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
3343  if (ParamLists[I]->size() == 0)
3344  HasAnyExplicitSpecHeader = true;
3345  else
3346  AllExplicitSpecHeaders = false;
3347  }
3348 
3349  if (!SuppressDiagnostic)
3350  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3351  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
3352  : diag::err_template_spec_extra_headers)
3353  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
3354  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
3355 
3356  // If there was a specialization somewhere, such that 'template<>' is
3357  // not required, and there were any 'template<>' headers, note where the
3358  // specialization occurred.
3359  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader &&
3360  !SuppressDiagnostic)
3361  Diag(ExplicitSpecLoc,
3362  diag::note_explicit_template_spec_does_not_need_header)
3363  << NestedTypes.back();
3364 
3365  // We have a template parameter list with no corresponding scope, which
3366  // means that the resulting template declaration can't be instantiated
3367  // properly (we'll end up with dependent nodes when we shouldn't).
3368  if (!AllExplicitSpecHeaders)
3369  Invalid = true;
3370  }
3371 
3372  // C++ [temp.expl.spec]p16:
3373  // In an explicit specialization declaration for a member of a class
3374  // template or a member template that ap- pears in namespace scope, the
3375  // member template and some of its enclosing class templates may remain
3376  // unspecialized, except that the declaration shall not explicitly
3377  // specialize a class member template if its en- closing class templates
3378  // are not explicitly specialized as well.
3379  if (ParamLists.back()->size() == 0 &&
3380  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3381  false))
3382  return nullptr;
3383 
3384  // Return the last template parameter list, which corresponds to the
3385  // entity being declared.
3386  return ParamLists.back();
3387 }
3388 
3390  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
3391  Diag(Template->getLocation(), diag::note_template_declared_here)
3392  << (isa<FunctionTemplateDecl>(Template)
3393  ? 0
3394  : isa<ClassTemplateDecl>(Template)
3395  ? 1
3396  : isa<VarTemplateDecl>(Template)
3397  ? 2
3398  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
3399  << Template->getDeclName();
3400  return;
3401  }
3402 
3403  if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
3404  for (OverloadedTemplateStorage::iterator I = OST->begin(),
3405  IEnd = OST->end();
3406  I != IEnd; ++I)
3407  Diag((*I)->getLocation(), diag::note_template_declared_here)
3408  << 0 << (*I)->getDeclName();
3409 
3410  return;
3411  }
3412 }
3413 
3414 static QualType
3416  const SmallVectorImpl<TemplateArgument> &Converted,
3417  SourceLocation TemplateLoc,
3418  TemplateArgumentListInfo &TemplateArgs) {
3419  ASTContext &Context = SemaRef.getASTContext();
3420  switch (BTD->getBuiltinTemplateKind()) {
3421  case BTK__make_integer_seq: {
3422  // Specializations of __make_integer_seq<S, T, N> are treated like
3423  // S<T, 0, ..., N-1>.
3424 
3425  // C++14 [inteseq.intseq]p1:
3426  // T shall be an integer type.
3427  if (!Converted[1].getAsType()->isIntegralType(Context)) {
3428  SemaRef.Diag(TemplateArgs[1].getLocation(),
3429  diag::err_integer_sequence_integral_element_type);
3430  return QualType();
3431  }
3432 
3433  // C++14 [inteseq.make]p1:
3434  // If N is negative the program is ill-formed.
3435  TemplateArgument NumArgsArg = Converted[2];
3436  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
3437  if (NumArgs < 0) {
3438  SemaRef.Diag(TemplateArgs[2].getLocation(),
3439  diag::err_integer_sequence_negative_length);
3440  return QualType();
3441  }
3442 
3443  QualType ArgTy = NumArgsArg.getIntegralType();
3444  TemplateArgumentListInfo SyntheticTemplateArgs;
3445  // The type argument gets reused as the first template argument in the
3446  // synthetic template argument list.
3447  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
3448  // Expand N into 0 ... N-1.
3449  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
3450  I < NumArgs; ++I) {
3451  TemplateArgument TA(Context, I, ArgTy);
3452  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
3453  TA, ArgTy, TemplateArgs[2].getLocation()));
3454  }
3455  // The first template argument will be reused as the template decl that
3456  // our synthetic template arguments will be applied to.
3457  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
3458  TemplateLoc, SyntheticTemplateArgs);
3459  }
3460 
3462  // Specializations of
3463  // __type_pack_element<Index, T_1, ..., T_N>
3464  // are treated like T_Index.
3465  assert(Converted.size() == 2 &&
3466  "__type_pack_element should be given an index and a parameter pack");
3467 
3468  // If the Index is out of bounds, the program is ill-formed.
3469  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
3470  llvm::APSInt Index = IndexArg.getAsIntegral();
3471  assert(Index >= 0 && "the index used with __type_pack_element should be of "
3472  "type std::size_t, and hence be non-negative");
3473  if (Index >= Ts.pack_size()) {
3474  SemaRef.Diag(TemplateArgs[0].getLocation(),
3475  diag::err_type_pack_element_out_of_bounds);
3476  return QualType();
3477  }
3478 
3479  // We simply return the type at index `Index`.
3480  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
3481  return Nth->getAsType();
3482  }
3483  llvm_unreachable("unexpected BuiltinTemplateDecl!");
3484 }
3485 
3486 /// Determine whether this alias template is "enable_if_t".
3487 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3488  return AliasTemplate->getName().equals("enable_if_t");
3489 }
3490 
3491 /// Collect all of the separable terms in the given condition, which
3492 /// might be a conjunction.
3493 ///
3494 /// FIXME: The right answer is to convert the logical expression into
3495 /// disjunctive normal form, so we can find the first failed term
3496 /// within each possible clause.
3497 static void collectConjunctionTerms(Expr *Clause,
3498  SmallVectorImpl<Expr *> &Terms) {
3499  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3500  if (BinOp->getOpcode() == BO_LAnd) {
3501  collectConjunctionTerms(BinOp->getLHS(), Terms);
3502  collectConjunctionTerms(BinOp->getRHS(), Terms);
3503  }
3504 
3505  return;
3506  }
3507 
3508  Terms.push_back(Clause);
3509 }
3510 
3511 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3512 // a left-hand side that is value-dependent but never true. Identify
3513 // the idiom and ignore that term.
3515  // Top-level '||'.
3516  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3517  if (!BinOp) return Cond;
3518 
3519  if (BinOp->getOpcode() != BO_LOr) return Cond;
3520 
3521  // With an inner '==' that has a literal on the right-hand side.
3522  Expr *LHS = BinOp->getLHS();
3523  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3524  if (!InnerBinOp) return Cond;
3525 
3526  if (InnerBinOp->getOpcode() != BO_EQ ||
3527  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3528  return Cond;
3529 
3530  // If the inner binary operation came from a macro expansion named
3531  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3532  // of the '||', which is the real, user-provided condition.
3533  SourceLocation Loc = InnerBinOp->getExprLoc();
3534  if (!Loc.isMacroID()) return Cond;
3535 
3536  StringRef MacroName = PP.getImmediateMacroName(Loc);
3537  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3538  return BinOp->getRHS();
3539 
3540  return Cond;
3541 }
3542 
3543 namespace {
3544 
3545 // A PrinterHelper that prints more helpful diagnostics for some sub-expressions
3546 // within failing boolean expression, such as substituting template parameters
3547 // for actual types.
3548 class FailedBooleanConditionPrinterHelper : public PrinterHelper {
3549 public:
3550  explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
3551  : Policy(P) {}
3552 
3553  bool handledStmt(Stmt *E, raw_ostream &OS) override {
3554  const auto *DR = dyn_cast<DeclRefExpr>(E);
3555  if (DR && DR->getQualifier()) {
3556  // If this is a qualified name, expand the template arguments in nested
3557  // qualifiers.
3558  DR->getQualifier()->print(OS, Policy, true);
3559  // Then print the decl itself.
3560  const ValueDecl *VD = DR->getDecl();
3561  OS << VD->getName();
3562  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3563  // This is a template variable, print the expanded template arguments.
3564  printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
3565  }
3566  return true;
3567  }
3568  return false;
3569  }
3570 
3571 private:
3572  const PrintingPolicy Policy;
3573 };
3574 
3575 } // end anonymous namespace
3576 
3577 std::pair<Expr *, std::string>
3579  Cond = lookThroughRangesV3Condition(PP, Cond);
3580 
3581  // Separate out all of the terms in a conjunction.
3582  SmallVector<Expr *, 4> Terms;
3583  collectConjunctionTerms(Cond, Terms);
3584 
3585  // Determine which term failed.
3586  Expr *FailedCond = nullptr;
3587  for (Expr *Term : Terms) {
3588  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3589 
3590  // Literals are uninteresting.
3591  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3592  isa<IntegerLiteral>(TermAsWritten))
3593  continue;
3594 
3595  // The initialization of the parameter from the argument is
3596  // a constant-evaluated context.
3597  EnterExpressionEvaluationContext ConstantEvaluated(
3599 
3600  bool Succeeded;
3601  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3602  !Succeeded) {
3603  FailedCond = TermAsWritten;
3604  break;
3605  }
3606  }
3607  if (!FailedCond)
3608  FailedCond = Cond->IgnoreParenImpCasts();
3609 
3610  std::string Description;
3611  {
3612  llvm::raw_string_ostream Out(Description);
3613  PrintingPolicy Policy = getPrintingPolicy();
3614  Policy.PrintCanonicalTypes = true;
3615  FailedBooleanConditionPrinterHelper Helper(Policy);
3616  FailedCond->printPretty(Out, &Helper, Policy, 0, "\n", nullptr);
3617  }
3618  return { FailedCond, Description };
3619 }
3620 
3622  SourceLocation TemplateLoc,
3623  TemplateArgumentListInfo &TemplateArgs) {
3625  = Name.getUnderlying().getAsDependentTemplateName();
3626  if (DTN && DTN->isIdentifier())
3627  // When building a template-id where the template-name is dependent,
3628  // assume the template is a type template. Either our assumption is
3629  // correct, or the code is ill-formed and will be diagnosed when the
3630  // dependent name is substituted.
3632  DTN->getQualifier(),
3633  DTN->getIdentifier(),
3634  TemplateArgs);
3635 
3636  if (Name.getAsAssumedTemplateName() &&
3637  resolveAssumedTemplateNameAsType(/*Scope*/nullptr, Name, TemplateLoc))
3638  return QualType();
3639 
3640  TemplateDecl *Template = Name.getAsTemplateDecl();
3641  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3642  isa<VarTemplateDecl>(Template) || isa<ConceptDecl>(Template)) {
3643  // We might have a substituted template template parameter pack. If so,
3644  // build a template specialization type for it.
3645  if (Name.getAsSubstTemplateTemplateParmPack())
3646  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3647 
3648  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3649  << Name;
3650  NoteAllFoundTemplates(Name);
3651  return QualType();
3652  }
3653 
3654  // Check that the template argument list is well-formed for this
3655  // template.
3657  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3658  false, Converted,
3659  /*UpdateArgsWithConversion=*/true))
3660  return QualType();
3661 
3662  QualType CanonType;
3663 
3665  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3666 
3667  // Find the canonical type for this type alias template specialization.
3668  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3669  if (Pattern->isInvalidDecl())
3670  return QualType();
3671 
3673  Converted);
3674 
3675  // Only substitute for the innermost template argument list.
3676  MultiLevelTemplateArgumentList TemplateArgLists;
3677  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3678  TemplateArgLists.addOuterRetainedLevels(
3679  AliasTemplate->getTemplateParameters()->getDepth());
3680 
3682  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3683  if (Inst.isInvalid())
3684  return QualType();
3685 
3686  CanonType = SubstType(Pattern->getUnderlyingType(),
3687  TemplateArgLists, AliasTemplate->getLocation(),
3688  AliasTemplate->getDeclName());
3689  if (CanonType.isNull()) {
3690  // If this was enable_if and we failed to find the nested type
3691  // within enable_if in a SFINAE context, dig out the specific
3692  // enable_if condition that failed and present that instead.
3694  if (auto DeductionInfo = isSFINAEContext()) {
3695  if (*DeductionInfo &&
3696  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3697  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3698  diag::err_typename_nested_not_found_enable_if &&
3699  TemplateArgs[0].getArgument().getKind()
3701  Expr *FailedCond;
3702  std::string FailedDescription;
3703  std::tie(FailedCond, FailedDescription) =
3704  findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
3705 
3706  // Remove the old SFINAE diagnostic.
3707  PartialDiagnosticAt OldDiag =
3709  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3710 
3711  // Add a new SFINAE diagnostic specifying which condition
3712  // failed.
3713  (*DeductionInfo)->addSFINAEDiagnostic(
3714  OldDiag.first,
3715  PDiag(diag::err_typename_nested_not_found_requirement)
3716  << FailedDescription
3717  << FailedCond->getSourceRange());
3718  }
3719  }
3720  }
3721 
3722  return QualType();
3723  }
3724  } else if (Name.isDependent() ||
3726  TemplateArgs, Converted)) {
3727  // This class template specialization is a dependent
3728  // type. Therefore, its canonical type is another class template
3729  // specialization type that contains all of the converted
3730  // arguments in canonical form. This ensures that, e.g., A<T> and
3731  // A<T, T> have identical types when A is declared as:
3732  //
3733  // template<typename T, typename U = T> struct A;
3734  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3735 
3736  // This might work out to be a current instantiation, in which
3737  // case the canonical type needs to be the InjectedClassNameType.
3738  //
3739  // TODO: in theory this could be a simple hashtable lookup; most
3740  // changes to CurContext don't change the set of current
3741  // instantiations.
3742  if (isa<ClassTemplateDecl>(Template)) {
3743  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3744  // If we get out to a namespace, we're done.
3745  if (Ctx->isFileContext()) break;
3746 
3747  // If this isn't a record, keep looking.
3748  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3749  if (!Record) continue;
3750 
3751  // Look for one of the two cases with InjectedClassNameTypes
3752  // and check whether it's the same template.
3753  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3754  !Record->getDescribedClassTemplate())
3755  continue;
3756 
3757  // Fetch the injected class name type and check whether its
3758  // injected type is equal to the type we just built.
3759  QualType ICNT = Context.getTypeDeclType(Record);
3760  QualType Injected = cast<InjectedClassNameType>(ICNT)
3761  ->getInjectedSpecializationType();
3762 
3763  if (CanonType != Injected->getCanonicalTypeInternal())
3764  continue;
3765 
3766  // If so, the canonical type of this TST is the injected
3767  // class name type of the record we just found.
3768  assert(ICNT.isCanonical());
3769  CanonType = ICNT;
3770  break;
3771  }
3772  }
3773  } else if (ClassTemplateDecl *ClassTemplate
3774  = dyn_cast<ClassTemplateDecl>(Template)) {
3775  // Find the class template specialization declaration that
3776  // corresponds to these arguments.
3777  void *InsertPos = nullptr;
3779  = ClassTemplate->findSpecialization(Converted, InsertPos);
3780  if (!Decl) {
3781  // This is the first time we have referenced this class template
3782  // specialization. Create the canonical declaration and add it to
3783  // the set of specializations.
3785  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3786  ClassTemplate->getDeclContext(),
3787  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3788  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3789  ClassTemplate->AddSpecialization(Decl, InsertPos);
3790  if (ClassTemplate->isOutOfLine())
3791  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3792  }
3793 
3794  if (Decl->getSpecializationKind() == TSK_Undeclared &&
3795  ClassTemplate->getTemplatedDecl()->hasAttrs()) {
3796  InstantiatingTemplate Inst(*this, TemplateLoc, Decl);
3797  if (!Inst.isInvalid()) {
3798  MultiLevelTemplateArgumentList TemplateArgLists;
3799  TemplateArgLists.addOuterTemplateArguments(Converted);
3800  InstantiateAttrsForDecl(TemplateArgLists,
3801  ClassTemplate->getTemplatedDecl(), Decl);
3802  }
3803  }
3804 
3805  // Diagnose uses of this specialization.
3806  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3807 
3808  CanonType = Context.getTypeDeclType(Decl);
3809  assert(isa<RecordType>(CanonType) &&
3810  "type of non-dependent specialization is not a RecordType");
3811  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3812  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3813  TemplateArgs);
3814  }
3815 
3816  // Build the fully-sugared type for this class template
3817  // specialization, which refers back to the class template
3818  // specialization we created or found.
3819  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3820 }
3821 
3823  TemplateNameKind &TNK,
3824  SourceLocation NameLoc,
3825  IdentifierInfo *&II) {
3826  assert(TNK == TNK_Undeclared_template && "not an undeclared template name");
3827 
3828  TemplateName Name = ParsedName.get();
3829  auto *ATN = Name.getAsAssumedTemplateName();
3830  assert(ATN && "not an assumed template name");
3831  II = ATN->getDeclName().getAsIdentifierInfo();
3832 
3833  if (!resolveAssumedTemplateNameAsType(S, Name, NameLoc, /*Diagnose*/false)) {
3834  // Resolved to a type template name.
3835  ParsedName = TemplateTy::make(Name);
3836  TNK = TNK_Type_template;
3837  }
3838 }
3839 
3841  SourceLocation NameLoc,
3842  bool Diagnose) {
3843  // We assumed this undeclared identifier to be an (ADL-only) function
3844  // template name, but it was used in a context where a type was required.
3845  // Try to typo-correct it now.
3846  AssumedTemplateStorage *ATN = Name.getAsAssumedTemplateName();
3847  assert(ATN && "not an assumed template name");
3848 
3849  LookupResult R(*this, ATN->getDeclName(), NameLoc, LookupOrdinaryName);
3850  struct CandidateCallback : CorrectionCandidateCallback {
3851  bool ValidateCandidate(const TypoCorrection &TC) override {
3852  return TC.getCorrectionDecl() &&
3854  }
3855  std::unique_ptr<CorrectionCandidateCallback> clone() override {
3856  return std::make_unique<CandidateCallback>(*this);
3857  }
3858  } FilterCCC;
3859 
3860  TypoCorrection Corrected =
3861  CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
3862  FilterCCC, CTK_ErrorRecovery);
3863  if (Corrected && Corrected.getFoundDecl()) {
3864  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest)
3865  << ATN->getDeclName());
3866  Name = TemplateName(Corrected.getCorrectionDeclAs<TemplateDecl>());
3867  return false;
3868  }
3869 
3870  if (Diagnose)
3871  Diag(R.getNameLoc(), diag::err_no_template) << R.getLookupName();
3872  return true;
3873 }
3874 
3876  Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
3877  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3878  SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
3879  ASTTemplateArgsPtr TemplateArgsIn, SourceLocation RAngleLoc,
3880  bool IsCtorOrDtorName, bool IsClassName) {
3881  if (SS.isInvalid())
3882  return true;
3883 
3884  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3885  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3886 
3887  // C++ [temp.res]p3:
3888  // A qualified-id that refers to a type and in which the
3889  // nested-name-specifier depends on a template-parameter (14.6.2)
3890  // shall be prefixed by the keyword typename to indicate that the
3891  // qualified-id denotes a type, forming an
3892  // elaborated-type-specifier (7.1.5.3).
3893  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3894  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3895  << SS.getScopeRep() << TemplateII->getName();
3896  // Recover as if 'typename' were specified.
3897  // FIXME: This is not quite correct recovery as we don't transform SS
3898  // into the corresponding dependent form (and we don't diagnose missing
3899  // 'template' keywords within SS as a result).
3900  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3901  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3902  TemplateArgsIn, RAngleLoc);
3903  }
3904 
3905  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3906  // it's not actually allowed to be used as a type in most cases. Because
3907  // we annotate it before we know whether it's valid, we have to check for
3908  // this case here.
3909  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3910  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3911  Diag(TemplateIILoc,
3912  TemplateKWLoc.isInvalid()
3913  ? diag::err_out_of_line_qualified_id_type_names_constructor
3914  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3915  << TemplateII << 0 /*injected-class-name used as template name*/
3916  << 1 /*if any keyword was present, it was 'template'*/;
3917  }
3918  }
3919 
3920  TemplateName Template = TemplateD.get();
3921  if (Template.getAsAssumedTemplateName() &&
3922  resolveAssumedTemplateNameAsType(S, Template, TemplateIILoc))
3923  return true;
3924 
3925  // Translate the parser's template argument list in our AST format.
3926  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3927  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3928 
3929  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3930  QualType T
3932  DTN->getQualifier(),
3933  DTN->getIdentifier(),
3934  TemplateArgs);
3935  // Build type-source information.
3936  TypeLocBuilder TLB;
3940  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3941  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3942  SpecTL.setTemplateNameLoc(TemplateIILoc);
3943  SpecTL.setLAngleLoc(LAngleLoc);
3944  SpecTL.setRAngleLoc(RAngleLoc);
3945  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3946  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3947  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3948  }
3949 
3950  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3951  if (Result.isNull())
3952  return true;
3953 
3954  // Build type-source information.
3955  TypeLocBuilder TLB;
3957  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3958  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3959  SpecTL.setTemplateNameLoc(TemplateIILoc);
3960  SpecTL.setLAngleLoc(LAngleLoc);
3961  SpecTL.setRAngleLoc(RAngleLoc);
3962  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3963  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3964 
3965  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3966  // constructor or destructor name (in such a case, the scope specifier
3967  // will be attached to the enclosing Decl or Expr node).
3968  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3969  // Create an elaborated-type-specifier containing the nested-name-specifier.
3970  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3971  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3973  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3974  }
3975 
3976  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3977 }
3978 
3980  TypeSpecifierType TagSpec,
3981  SourceLocation TagLoc,
3982  CXXScopeSpec &SS,
3983  SourceLocation TemplateKWLoc,
3984  TemplateTy TemplateD,
3985  SourceLocation TemplateLoc,
3986  SourceLocation LAngleLoc,
3987  ASTTemplateArgsPtr TemplateArgsIn,
3988  SourceLocation RAngleLoc) {
3989  if (SS.isInvalid())
3990  return TypeResult(true);
3991 
3992  TemplateName Template = TemplateD.get();
3993 
3994  // Translate the parser's template argument list in our AST format.
3995  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3996  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3997 
3998  // Determine the tag kind
4000  ElaboratedTypeKeyword Keyword
4002 
4003  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
4005  DTN->getQualifier(),
4006  DTN->getIdentifier(),
4007  TemplateArgs);
4008 
4009  // Build type-source information.
4010  TypeLocBuilder TLB;
4013  SpecTL.setElaboratedKeywordLoc(TagLoc);
4014  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
4015  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4016  SpecTL.setTemplateNameLoc(TemplateLoc);
4017  SpecTL.setLAngleLoc(LAngleLoc);
4018  SpecTL.setRAngleLoc(RAngleLoc);
4019  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
4020  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
4021  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
4022  }
4023 
4024  if (TypeAliasTemplateDecl *TAT =
4025  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
4026  // C++0x [dcl.type.elab]p2:
4027  // If the identifier resolves to a typedef-name or the simple-template-id
4028  // resolves to an alias template specialization, the
4029  // elaborated-type-specifier is ill-formed.
4030  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
4031  << TAT << NTK_TypeAliasTemplate << TagKind;
4032  Diag(TAT->getLocation(), diag::note_declared_at);
4033  }
4034 
4035  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
4036  if (Result.isNull())
4037  return TypeResult(true);
4038 
4039  // Check the tag kind
4040  if (const RecordType *RT = Result->getAs<RecordType>()) {
4041  RecordDecl *D = RT->getDecl();
4042 
4044  assert(Id && "templated class must have an identifier");
4045 
4046  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
4047  TagLoc, Id)) {
4048  Diag(TagLoc, diag::err_use_with_wrong_tag)
4049  << Result
4051  Diag(D->getLocation(), diag::note_previous_use);
4052  }
4053  }
4054 
4055  // Provide source-location information for the template specialization.
4056  TypeLocBuilder TLB;
4058  = TLB.push<TemplateSpecializationTypeLoc>(Result);
4059  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4060  SpecTL.setTemplateNameLoc(TemplateLoc);
4061  SpecTL.setLAngleLoc(LAngleLoc);
4062  SpecTL.setRAngleLoc(RAngleLoc);
4063  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
4064  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
4065 
4066  // Construct an elaborated type containing the nested-name-specifier (if any)
4067  // and tag keyword.
4068  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
4069  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
4070  ElabTL.setElaboratedKeywordLoc(TagLoc);
4071  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
4072  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
4073 }
4074 
4075 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
4076  NamedDecl *PrevDecl,
4077  SourceLocation Loc,
4079 
4081 
4083  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
4084  switch (Arg.getKind()) {
4091  return false;
4092 
4093  case TemplateArgument::Type: {
4094  QualType Type = Arg.getAsType();
4095  const TemplateTypeParmType *TPT =
4097  return TPT && !Type.hasQualifiers() &&
4098  TPT->getDepth() == Depth && TPT->getIndex() == Index;
4099  }
4100 
4102  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
4103  if (!DRE || !DRE->getDecl())
4104  return false;
4105  const NonTypeTemplateParmDecl *NTTP =
4106  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4107  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
4108  }
4109 
4111  const TemplateTemplateParmDecl *TTP =
4112  dyn_cast_or_null<TemplateTemplateParmDecl>(
4114  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
4115  }
4116  llvm_unreachable("unexpected kind of template argument");
4117 }
4118 
4121  if (Params->size() != Args.size())
4122  return false;
4123 
4124  unsigned Depth = Params->getDepth();
4125 
4126  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
4127  TemplateArgument Arg = Args[I];
4128 
4129  // If the parameter is a pack expansion, the argument must be a pack
4130  // whose only element is a pack expansion.
4131  if (Params->getParam(I)->isParameterPack()) {
4132  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
4133  !Arg.pack_begin()->isPackExpansion())
4134  return false;
4135  Arg = Arg.pack_begin()->getPackExpansionPattern();
4136  }
4137 
4139  return false;
4140  }
4141 
4142  return true;
4143 }
4144 
4145 template<typename PartialSpecDecl>
4146 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
4147  if (Partial->getDeclContext()->isDependentContext())
4148  return;
4149 
4150  // FIXME: Get the TDK from deduction in order to provide better diagnostics
4151  // for non-substitution-failure issues?
4152  TemplateDeductionInfo Info(Partial->getLocation());
4153  if (S.isMoreSpecializedThanPrimary(Partial, Info))
4154  return;
4155 
4156  auto *Template = Partial->getSpecializedTemplate();
4157  S.Diag(Partial->getLocation(),
4158  diag::ext_partial_spec_not_more_specialized_than_primary)
4159  << isa<VarTemplateDecl>(Template);
4160 
4161  if (Info.hasSFINAEDiagnostic()) {
4164  Info.takeSFINAEDiagnostic(Diag);
4165  SmallString<128> SFINAEArgString;
4166  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
4167  S.Diag(Diag.first,
4168  diag::note_partial_spec_not_more_specialized_than_primary)
4169  << SFINAEArgString;
4170  }
4171 
4172  S.Diag(Template->getLocation(), diag::note_template_decl_here);
4173  SmallVector<const Expr *, 3> PartialAC, TemplateAC;
4174  Template->getAssociatedConstraints(TemplateAC);
4175  Partial->getAssociatedConstraints(PartialAC);
4176  S.MaybeEmitAmbiguousAtomicConstraintsDiagnostic(Partial, PartialAC, Template,
4177  TemplateAC);
4178 }
4179 
4180 static void
4182  const llvm::SmallBitVector &DeducibleParams) {
4183  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
4184  if (!DeducibleParams[I]) {
4185  NamedDecl *Param = TemplateParams->getParam(I);
4186  if (Param->getDeclName())
4187  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4188  << Param->getDeclName();
4189  else
4190  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4191  << "(anonymous)";
4192  }
4193  }
4194 }
4195 
4196 
4197 template<typename PartialSpecDecl>
4199  PartialSpecDecl *Partial) {
4200  // C++1z [temp.class.spec]p8: (DR1495)
4201  // - The specialization shall be more specialized than the primary
4202  // template (14.5.5.2).
4203  checkMoreSpecializedThanPrimary(S, Partial);
4204 
4205  // C++ [temp.class.spec]p8: (DR1315)
4206  // - Each template-parameter shall appear at least once in the
4207  // template-id outside a non-deduced context.
4208  // C++1z [temp.class.spec.match]p3 (P0127R2)
4209  // If the template arguments of a partial specialization cannot be
4210  // deduced because of the structure of its template-parameter-list
4211  // and the template-id, the program is ill-formed.
4212  auto *TemplateParams = Partial->getTemplateParameters();
4213  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4214  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
4215  TemplateParams->getDepth(), DeducibleParams);
4216 
4217  if (!DeducibleParams.all()) {
4218  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4219  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
4220  << isa<VarTemplatePartialSpecializationDecl>(Partial)
4221  << (NumNonDeducible > 1)
4222  << SourceRange(Partial->getLocation(),
4223  Partial->getTemplateArgsAsWritten()->RAngleLoc);
4224  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
4225  }
4226 }
4227 
4230  checkTemplatePartialSpecialization(*this, Partial);
4231 }
4232 
4235  checkTemplatePartialSpecialization(*this, Partial);
4236 }
4237 
4239  // C++1z [temp.param]p11:
4240  // A template parameter of a deduction guide template that does not have a
4241  // default-argument shall be deducible from the parameter-type-list of the
4242  // deduction guide template.
4243  auto *TemplateParams = TD->getTemplateParameters();
4244  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4245  MarkDeducedTemplateParameters(TD, DeducibleParams);
4246  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
4247  // A parameter pack is deducible (to an empty pack).
4248  auto *Param = TemplateParams->getParam(I);
4249  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
4250  DeducibleParams[I] = true;
4251  }
4252 
4253  if (!DeducibleParams.all()) {
4254  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4255  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
4256  << (NumNonDeducible > 1);
4257  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
4258  }
4259 }
4260 
4262  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
4263  TemplateParameterList *TemplateParams, StorageClass SC,
4264  bool IsPartialSpecialization) {
4265  // D must be variable template id.
4267  "Variable template specialization is declared with a template it.");
4268 
4269  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
4270  TemplateArgumentListInfo TemplateArgs =
4271  makeTemplateArgumentListInfo(*this, *TemplateId);
4272  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
4273  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
4274  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
4275 
4276  TemplateName Name = TemplateId->Template.get();
4277 
4278  // The template-id must name a variable template.
4279  VarTemplateDecl *VarTemplate =
4280  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
4281  if (!VarTemplate) {
4282  NamedDecl *FnTemplate;
4283  if (auto *OTS = Name.getAsOverloadedTemplate())
4284  FnTemplate = *OTS->begin();
4285  else
4286  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
4287  if (FnTemplate)
4288  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
4289  << FnTemplate->getDeclName();
4290  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
4292  }
4293 
4294  // Check for unexpanded parameter packs in any of the template arguments.
4295  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
4296  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
4297  UPPC_PartialSpecialization))
4298  return true;
4299 
4300  // Check that the template argument list is well-formed for this
4301  // template.
4303  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
4304  false, Converted,
4305  /*UpdateArgsWithConversion=*/true))
4306  return true;
4307 
4308  // Find the variable template (partial) specialization declaration that
4309  // corresponds to these arguments.
4311  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
4312  TemplateArgs.size(), Converted))
4313  return true;
4314 
4315  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
4316  // also do them during instantiation.
4317  if (!Name.isDependent() &&
4319  Converted)) {
4320  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
4321  << VarTemplate->getDeclName();
4322  IsPartialSpecialization = false;
4323  }
4324 
4326  Converted) &&
4327  (!Context.getLangOpts().CPlusPlus20 ||
4328  !TemplateParams->hasAssociatedConstraints())) {
4329  // C++ [temp.class.spec]p9b3:
4330  //
4331  // -- The argument list of the specialization shall not be identical
4332  // to the implicit argument list of the primary template.
4333  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
4334  << /*variable template*/ 1
4335  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
4336  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
4337  // FIXME: Recover from this by treating the declaration as a redeclaration
4338  // of the primary template.
4339  return true;
4340  }
4341  }
4342 
4343  void *InsertPos = nullptr;
4344  VarTemplateSpecializationDecl *PrevDecl = nullptr;
4345 
4347  PrevDecl = VarTemplate->findPartialSpecialization(Converted, TemplateParams,
4348  InsertPos);
4349  else
4350  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
4351 
4353 
4354  // Check whether we can declare a variable template specialization in
4355  // the current scope.
4356  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
4357  TemplateNameLoc,
4359  return true;
4360 
4361  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
4362  // Since the only prior variable template specialization with these
4363  // arguments was referenced but not declared, reuse that
4364  // declaration node as our own, updating its source location and
4365  // the list of outer template parameters to reflect our new declaration.
4366  Specialization = PrevDecl;
4367  Specialization->setLocation(TemplateNameLoc);
4368  PrevDecl = nullptr;
4369  } else if (IsPartialSpecialization) {
4370  // Create a new class template partial specialization declaration node.
4372  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
4375  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
4376  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
4377  Converted, TemplateArgs);
4378 
4379  if (!PrevPartial)
4380  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
4381  Specialization = Partial;
4382 
4383  // If we are providing an explicit specialization of a member variable
4384  // template specialization, make a note of that.
4385  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
4386  PrevPartial->setMemberSpecialization();
4387 
4388  CheckTemplatePartialSpecialization(Partial);
4389  } else {
4390  // Create a new class template specialization declaration node for
4391  // this explicit specialization or friend declaration.
4393  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
4394  VarTemplate, DI->getType(), DI, SC, Converted);
4395  Specialization->setTemplateArgsInfo(TemplateArgs);
4396 
4397  if (!PrevDecl)
4398  VarTemplate->AddSpecialization(Specialization, InsertPos);
4399  }
4400 
4401  // C++ [temp.expl.spec]p6:
4402  // If a template, a member template or the member of a class template is
4403  // explicitly specialized then that specialization shall be declared
4404  // before the first use of that specialization that would cause an implicit
4405  // instantiation to take place, in every translation unit in which such a
4406  // use occurs; no diagnostic is required.
4407  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
4408  bool Okay = false;
4409  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
4410  // Is there any previous explicit specialization declaration?
4412  Okay = true;
4413  break;
4414  }
4415  }
4416 
4417  if (!Okay) {
4418  SourceRange Range(TemplateNameLoc, RAngleLoc);
4419  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
4420  << Name << Range;
4421 
4422  Diag(PrevDecl->getPointOfInstantiation(),
4423  diag::note_instantiation_required_here)
4424  << (PrevDecl->getTemplateSpecializationKind() !=
4426  return true;
4427  }
4428  }
4429 
4430  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
4431  Specialization->setLexicalDeclContext(CurContext);
4432 
4433  // Add the specialization into its lexical context, so that it can
4434  // be seen when iterating through the list of declarations in that
4435  // context. However, specializations are not found by name lookup.
4436  CurContext->addDecl(Specialization);
4437 
4438  // Note that this is an explicit specialization.
4439  Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
4440 
4441  if (PrevDecl) {
4442  // Check that this isn't a redefinition of this specialization,
4443  // merging with previous declarations.
4444  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
4445  forRedeclarationInCurContext());
4446  PrevSpec.addDecl(PrevDecl);
4447  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
4448  } else if (Specialization->isStaticDataMember() &&
4449  Specialization->isOutOfLine()) {
4450  Specialization->setAccess(VarTemplate->getAccess());
4451  }
4452 
4453  return Specialization;
4454 }
4455 
4456 namespace {
4457 /// A partial specialization whose template arguments have matched
4458 /// a given template-id.
4459 struct PartialSpecMatchResult {
4461  TemplateArgumentList *Args;
4462 };
4463 } // end anonymous namespace
4464 
4465 DeclResult
4467  SourceLocation TemplateNameLoc,
4468  const TemplateArgumentListInfo &TemplateArgs) {
4469  assert(Template && "A variable template id without template?");
4470 
4471  // Check that the template argument list is well-formed for this template.
4473  if (CheckTemplateArgumentList(
4474  Template, TemplateNameLoc,
4475  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
4476  Converted, /*UpdateArgsWithConversion=*/true))
4477  return true;
4478 
4479  // Produce a placeholder value if the specialization is dependent.
4480  if (Template->getDeclContext()->isDependentContext() ||
4482  Converted))
4483  return DeclResult();
4484 
4485  // Find the variable template specialization declaration that
4486  // corresponds to these arguments.
4487  void *InsertPos = nullptr;
4488  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
4489  Converted, InsertPos)) {
4490  checkSpecializationVisibility(TemplateNameLoc, Spec);
4491  // If we already have a variable template specialization, return it.
4492  return Spec;
4493  }
4494 
4495  // This is the first time we have referenced this variable template
4496  // specialization. Create the canonical declaration and add it to
4497  // the set of specializations, based on the closest partial specialization
4498  // that it represents. That is,
4499  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
4501  Converted);
4502  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
4503  bool AmbiguousPartialSpec = false;
4504  typedef PartialSpecMatchResult MatchResult;
4506  SourceLocation PointOfInstantiation = TemplateNameLoc;
4507  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
4508  /*ForTakingAddress=*/false);
4509 
4510  // 1. Attempt to find the closest partial specialization that this
4511  // specializes, if any.
4512  // TODO: Unify with InstantiateClassTemplateSpecialization()?
4513  // Perhaps better after unification of DeduceTemplateArguments() and
4514  // getMoreSpecializedPartialSpecialization().
4516  Template->getPartialSpecializations(PartialSpecs);
4517 
4518  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
4519  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
4520  TemplateDeductionInfo Info(FailedCandidates.getLocation());
4521 
4522  if (TemplateDeductionResult Result =
4523  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
4524  // Store the failed-deduction information for use in diagnostics, later.
4525  // TODO: Actually use the failed-deduction info?
4526  FailedCandidates.addCandidate().set(
4527  DeclAccessPair::make(Template, AS_public), Partial,
4528  MakeDeductionFailureInfo(Context, Result, Info));
4529  (void)Result;
4530  } else {
4531  Matched.push_back(PartialSpecMatchResult());
4532  Matched.back().Partial = Partial;
4533  Matched.back().Args = Info.take();
4534  }
4535  }
4536 
4537  if (Matched.size() >= 1) {
4538  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
4539  if (Matched.size() == 1) {
4540  // -- If exactly one matching specialization is found, the
4541  // instantiation is generated from that specialization.
4542  // We don't need to do anything for this.
4543  } else {
4544  // -- If more than one matching specialization is found, the
4545  // partial order rules (14.5.4.2) are used to determine
4546  // whether one of the specializations is more specialized
4547  // than the others. If none of the specializations is more
4548  // specialized than all of the other matching
4549  // specializations, then the use of the variable template is
4550  // ambiguous and the program is ill-formed.
4551  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4552  PEnd = Matched.end();
4553  P != PEnd; ++P) {
4554  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4555  PointOfInstantiation) ==
4556  P->Partial)
4557  Best = P;
4558  }
4559 
4560  // Determine if the best partial specialization is more specialized than
4561  // the others.
4562  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4563  PEnd = Matched.end();
4564  P != PEnd; ++P) {
4565  if (P != Best && getMoreSpecializedPartialSpecialization(
4566  P->Partial, Best->Partial,
4567  PointOfInstantiation) != Best->Partial) {
4568  AmbiguousPartialSpec = true;
4569  break;
4570  }
4571  }
4572  }
4573 
4574  // Instantiate using the best variable template partial specialization.
4575  InstantiationPattern = Best->Partial;
4576  InstantiationArgs = Best->Args;
4577  } else {
4578  // -- If no match is found, the instantiation is generated
4579  // from the primary template.
4580  // InstantiationPattern = Template->getTemplatedDecl();
4581  }
4582 
4583  // 2. Create the canonical declaration.
4584  // Note that we do not instantiate a definition until we see an odr-use
4585  // in DoMarkVarDeclReferenced().
4586  // FIXME: LateAttrs et al.?
4587  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4588  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4589  Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
4590  if (!Decl)
4591  return true;
4592 
4593  if (AmbiguousPartialSpec) {
4594  // Partial ordering did not produce a clear winner. Complain.
4595  Decl->setInvalidDecl();
4596  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4597  << Decl;
4598 
4599  // Print the matching partial specializations.
4600  for (MatchResult P : Matched)
4601  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4602  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4603  *P.Args);
4604  return true;
4605  }
4606 
4608  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4609  Decl->setInstantiationOf(D, InstantiationArgs);
4610 
4611  checkSpecializationVisibility(TemplateNameLoc, Decl);
4612 
4613  assert(Decl && "No variable template specialization?");
4614  return Decl;
4615 }
4616 
4617 ExprResult
4619  const DeclarationNameInfo &NameInfo,
4620  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4621  const TemplateArgumentListInfo *TemplateArgs) {
4622 
4623  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4624  *TemplateArgs);
4625  if (Decl.isInvalid())
4626  return ExprError();
4627 
4628  if (!Decl.get())
4629  return ExprResult();
4630 
4631  VarDecl *Var = cast<VarDecl>(Decl.get());
4632  if (!Var->getTemplateSpecializationKind())
4634  NameInfo.getLoc());
4635 
4636  // Build an ordinary singleton decl ref.
4637  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4638  /*FoundD=*/nullptr, TemplateArgs);
4639 }
4640 
4642  SourceLocation Loc) {
4643  Diag(Loc, diag::err_template_missing_args)
4644  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4645  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4646  Diag(TD->getLocation(), diag::note_template_decl_here)
4647  << TD->getTemplateParameters()->getSourceRange();
4648  }
4649 }
4650 
4651 ExprResult
4653  SourceLocation TemplateKWLoc,
4654  const DeclarationNameInfo &ConceptNameInfo,
4655  NamedDecl *FoundDecl,
4656  ConceptDecl *NamedConcept,
4657  const TemplateArgumentListInfo *TemplateArgs) {
4658  assert(NamedConcept && "A concept template id without a template?");
4659 
4661  if (CheckTemplateArgumentList(NamedConcept, ConceptNameInfo.getLoc(),
4662  const_cast<TemplateArgumentListInfo&>(*TemplateArgs),
4663  /*PartialTemplateArgs=*/false, Converted,
4664  /*UpdateArgsWithConversion=*/false))
4665  return ExprError();
4666 
4667  ConstraintSatisfaction Satisfaction;
4668  bool AreArgsDependent =
4670  Converted);
4671  if (!AreArgsDependent &&
4673  NamedConcept, {NamedConcept->getConstraintExpr()}, Converted,
4674  SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameInfo.getLoc(),
4675  TemplateArgs->getRAngleLoc()),
4676  Satisfaction))
4677  return ExprError();
4678 
4679  return ConceptSpecializationExpr::Create(Context,
4680  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
4681  TemplateKWLoc, ConceptNameInfo, FoundDecl, NamedConcept,
4682  ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
4683  AreArgsDependent ? nullptr : &Satisfaction);
4684 }
4685 
4687  SourceLocation TemplateKWLoc,
4688  LookupResult &R,
4689  bool RequiresADL,
4690  const TemplateArgumentListInfo *TemplateArgs) {
4691  // FIXME: Can we do any checking at this point? I guess we could check the
4692  // template arguments that we have against the template name, if the template
4693  // name refers to a single template. That's not a terribly common case,
4694  // though.
4695  // foo<int> could identify a single function unambiguously
4696  // This approach does NOT work, since f<int>(1);
4697  // gets resolved prior to resorting to overload resolution
4698  // i.e., template<class T> void f(double);
4699  // vs template<class T, class U> void f(U);
4700 
4701  // These should be filtered out by our callers.
4702  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4703 
4704  // Non-function templates require a template argument list.
4705  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4706  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4707  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4708  return ExprError();
4709  }
4710  }
4711 
4712  // In C++1y, check variable template ids.
4713  if (R.getAsSingle<VarTemplateDecl>()) {
4714  ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
4716  TemplateKWLoc, TemplateArgs);
4717  if (Res.isInvalid() || Res.isUsable())
4718  return Res;
4719  // Result is dependent. Carry on to build an UnresolvedLookupEpxr.
4720  }
4721 
4722  if (R.getAsSingle<ConceptDecl>()) {
4723  return CheckConceptTemplateId(SS, TemplateKWLoc, R.getLookupNameInfo(),
4724  R.getFoundDecl(),
4725  R.getAsSingle<ConceptDecl>(), TemplateArgs);
4726  }
4727 
4728  // We don't want lookup warnings at this point.
4729  R.suppressDiagnostics();
4730 
4733  SS.getWithLocInContext(Context),
4734  TemplateKWLoc,
4735  R.getLookupNameInfo(),
4736  RequiresADL, TemplateArgs,
4737  R.begin(), R.end());
4738 
4739  return ULE;
4740 }
4741 
4742 // We actually only call this from template instantiation.
4743 ExprResult
4745  SourceLocation TemplateKWLoc,
4746  const DeclarationNameInfo &NameInfo,
4747  const TemplateArgumentListInfo *TemplateArgs) {
4748 
4749  assert(TemplateArgs || TemplateKWLoc.isValid());
4750  DeclContext *DC;
4751  if (!(DC = computeDeclContext(SS, false)) ||
4752  DC->isDependentContext() ||
4753  RequireCompleteDeclContext(SS, DC))
4754  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4755 
4756  bool MemberOfUnknownSpecialization;
4757  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4758  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4759  /*Entering*/false, MemberOfUnknownSpecialization,
4760  TemplateKWLoc))
4761  return ExprError();
4762 
4763  if (R.isAmbiguous())
4764  return ExprError();
4765 
4766  if (R.empty()) {
4767  Diag(NameInfo.getLoc(), diag::err_no_member)
4768  << NameInfo.getName() << DC << SS.getRange();
4769  return ExprError();
4770  }
4771 
4772  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4773  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4774  << SS.getScopeRep()
4775  << NameInfo.getName().getAsString() << SS.getRange();
4776  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4777  return ExprError();
4778  }
4779 
4780  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4781 }
4782 
4783 /// Form a template name from a name that is syntactically required to name a
4784 /// template, either due to use of the 'template' keyword or because a name in
4785 /// this syntactic context is assumed to name a template (C++ [temp.names]p2-4).
4786 ///
4787 /// This action forms a template name given the name of the template and its
4788 /// optional scope specifier. This is used when the 'template' keyword is used
4789 /// or when the parsing context unambiguously treats a following '<' as
4790 /// introducing a template argument list. Note that this may produce a
4791 /// non-dependent template name if we can perform the lookup now and identify
4792 /// the named template.
4793 ///
4794 /// For example, given "x.MetaFun::template apply", the scope specifier
4795 /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
4796 /// of the "template" keyword, and "apply" is the \p Name.
4798  CXXScopeSpec &SS,
4799  SourceLocation TemplateKWLoc,
4800  const UnqualifiedId &Name,
4801  ParsedType ObjectType,
4802  bool EnteringContext,
4803  TemplateTy &Result,
4804  bool AllowInjectedClassName) {
4805  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4806  Diag(TemplateKWLoc,
4807  getLangOpts().CPlusPlus11 ?
4808  diag::warn_cxx98_compat_template_outside_of_template :
4809  diag::ext_template_outside_of_template)
4810  << FixItHint::CreateRemoval(TemplateKWLoc);
4811 
4812  if (SS.isInvalid())
4813  return TNK_Non_template;
4814 
4815  // Figure out where isTemplateName is going to look.
4816  DeclContext *LookupCtx = nullptr;
4817  if (SS.isNotEmpty())
4818  LookupCtx = computeDeclContext(SS, EnteringContext);
4819  else if (ObjectType)
4820  LookupCtx = computeDeclContext(GetTypeFromParser(ObjectType));
4821 
4822  // C++0x [temp.names]p5:
4823  // If a name prefixed by the keyword template is not the name of
4824  // a template, the program is ill-formed. [Note: the keyword
4825  // template may not be applied to non-template members of class
4826  // templates. -end note ] [ Note: as is the case with the
4827  // typename prefix, the template prefix is allowed in cases
4828  // where it is not strictly necessary; i.e., when the
4829  // nested-name-specifier or the expression on the left of the ->
4830  // or . is not dependent on a template-parameter, or the use
4831  // does not appear in the scope of a template. -end note]
4832  //
4833  // Note: C++03 was more strict here, because it banned the use of
4834  // the "template" keyword prior to a template-name that was not a
4835  // dependent name. C++ DR468 relaxed this requirement (the
4836  // "template" keyword is now permitted). We follow the C++0x
4837  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4838  bool MemberOfUnknownSpecialization;
4839  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4840  ObjectType, EnteringContext, Result,
4841  MemberOfUnknownSpecialization);
4842  if (TNK != TNK_Non_template) {
4843  // We resolved this to a (non-dependent) template name. Return it.
4844  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
4845  if (!AllowInjectedClassName && SS.isNotEmpty() && LookupRD &&
4846  Name.getKind() == UnqualifiedIdKind::IK_Identifier &&
4847  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4848  // C++14 [class.qual]p2:
4849  // In a lookup in which function names are not ignored and the
4850  // nested-name-specifier nominates a class C, if the name specified
4851  // [...] is the injected-class-name of C, [...] the name is instead
4852  // considered to name the constructor
4853  //
4854  // We don't get here if naming the constructor would be valid, so we
4855  // just reject immediately and recover by treating the
4856  // injected-class-name as naming the template.
4857  Diag(Name.getBeginLoc(),
4858  diag::ext_out_of_line_qualified_id_type_names_constructor)
4859  << Name.Identifier
4860  << 0 /*injected-class-name used as template name*/
4861  << TemplateKWLoc.isValid();
4862  }
4863  return TNK;
4864  }
4865 
4866  if (!MemberOfUnknownSpecialization) {
4867  // Didn't find a template name, and the lookup wasn't dependent.
4868  // Do the lookup again to determine if this is a "nothing found" case or
4869  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4870  // need to do this.
4871  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4872  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4873  LookupOrdinaryName);
4874  bool MOUS;
4875  // Tell LookupTemplateName that we require a template so that it diagnoses
4876  // cases where it finds a non-template.
4877  RequiredTemplateKind RTK = TemplateKWLoc.isValid()
4878  ? RequiredTemplateKind(TemplateKWLoc)
4879  : TemplateNameIsRequired;
4880  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext, MOUS,
4881  RTK, nullptr, /*AllowTypoCorrection=*/false) &&
4882  !R.isAmbiguous()) {
4883  if (LookupCtx)
4884  Diag(Name.getBeginLoc(), diag::err_no_member)
4885  << DNI.getName() << LookupCtx << SS.getRange();
4886  else
4887  Diag(Name.getBeginLoc(), diag::err_undeclared_use)
4888  << DNI.getName() << SS.getRange();
4889  }
4890  return TNK_Non_template;
4891  }
4892 
4893  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4894 
4895  switch (Name.getKind()) {
4897  Result = TemplateTy::make(
4898  Context.getDependentTemplateName(Qualifier, Name.Identifier));
4900 
4902  Result = TemplateTy::make(Context.getDependentTemplateName(
4903  Qualifier, Name.OperatorFunctionId.Operator));
4904  return TNK_Function_template;
4905 
4907  // This is a kind of template name, but can never occur in a dependent
4908  // scope (literal operators can only be declared at namespace scope).
4909  break;
4910 
4911  default:
4912  break;
4913  }
4914 
4915  // This name cannot possibly name a dependent template. Diagnose this now
4916  // rather than building a dependent template name that can never be valid.
4917  Diag(Name.getBeginLoc(),
4918  diag::err_template_kw_refers_to_dependent_non_template)
4919  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4920  << TemplateKWLoc.isValid() << TemplateKWLoc;
4921  return TNK_Non_template;
4922 }
4923 
4925  TemplateArgumentLoc &AL,
4926  SmallVectorImpl<TemplateArgument> &Converted) {
4927  const TemplateArgument &Arg = AL.getArgument();
4928  QualType ArgType;
4929  TypeSourceInfo *TSI = nullptr;
4930 
4931  // Check template type parameter.
4932  switch(Arg.getKind()) {
4934  // C++ [temp.arg.type]p1:
4935  // A template-argument for a template-parameter which is a
4936  // type shall be a type-id.
4937  ArgType = Arg.getAsType();
4938  TSI = AL.getTypeSourceInfo();
4939  break;
4942  // We have a template type parameter but the template argument
4943  // is a template without any arguments.
4944  SourceRange SR = AL.getSourceRange();
4946  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4947  return true;
4948  }
4950  // We have a template type parameter but the template argument is an
4951  // expression; see if maybe it is missing the "typename" keyword.
4952  CXXScopeSpec SS;
4953  DeclarationNameInfo NameInfo;
4954 
4955  if (DependentScopeDeclRefExpr *ArgExpr =
4956  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4957  SS.Adopt(ArgExpr->getQualifierLoc());
4958  NameInfo = ArgExpr->getNameInfo();
4959  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4960  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4961  if (ArgExpr->isImplicitAccess()) {
4962  SS.Adopt(ArgExpr->getQualifierLoc());
4963  NameInfo = ArgExpr->getMemberNameInfo();
4964  }
4965  }
4966 
4967  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4968  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4969  LookupParsedName(Result, CurScope, &SS);
4970 
4971  if (Result.getAsSingle<TypeDecl>() ||
4972  Result.getResultKind() ==
4974  assert(SS.getScopeRep() && "dependent scope expr must has a scope!");
4975  // Suggest that the user add 'typename' before the NNS.
4976  SourceLocation Loc = AL.getSourceRange().getBegin();
4977  Diag(Loc, getLangOpts().MSVCCompat
4978  ? diag::ext_ms_template_type_arg_missing_typename
4979  : diag::err_template_arg_must_be_type_suggest)
4980  << FixItHint::CreateInsertion(Loc, "typename ");
4981  Diag(Param->getLocation(), diag::note_template_param_here);
4982 
4983  // Recover by synthesizing a type using the location information that we
4984  // already have.
4985  ArgType =
4986  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4987  TypeLocBuilder TLB;
4988  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4989  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4990  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4991  TL.setNameLoc(NameInfo.getLoc());
4992  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4993 
4994  // Overwrite our input TemplateArgumentLoc so that we can recover
4995  // properly.
4996  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
4998 
4999  break;
5000  }
5001  }
5002  // fallthrough
5003  LLVM_FALLTHROUGH;
5004  }
5005  default: {
5006  // We have a template type parameter but the template argument
5007  // is not a type.
5008  SourceRange SR = AL.getSourceRange();
5009  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
5010  Diag(Param->getLocation(), diag::note_template_param_here);
5011 
5012  return true;
5013  }
5014  }
5015 
5016  if (CheckTemplateArgument(Param, TSI))
5017  return true;
5018 
5019  // Add the converted template type argument.
5020  ArgType = Context.getCanonicalType(ArgType);
5021 
5022  // Objective-C ARC:
5023  // If an explicitly-specified template argument type is a lifetime type
5024  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
5025  if (getLangOpts().ObjCAutoRefCount &&
5026  ArgType->isObjCLifetimeType() &&
5027  !ArgType.getObjCLifetime()) {
5028  Qualifiers Qs;
5030  ArgType = Context.getQualifiedType(ArgType, Qs);
5031  }
5032 
5033  Converted.push_back(TemplateArgument(ArgType));
5034  return false;
5035 }
5036 
5037 /// Substitute template arguments into the default template argument for
5038 /// the given template type parameter.
5039 ///
5040 /// \param SemaRef the semantic analysis object for which we are performing
5041 /// the substitution.
5042 ///
5043 /// \param Template the template that we are synthesizing template arguments
5044 /// for.
5045 ///
5046 /// \param TemplateLoc the location of the template name that started the
5047 /// template-id we are checking.
5048 ///
5049 /// \param RAngleLoc the location of the right angle bracket ('>') that
5050 /// terminates the template-id.
5051 ///
5052 /// \param Param the template template parameter whose default we are
5053 /// substituting into.
5054 ///
5055 /// \param Converted the list of template arguments provided for template
5056 /// parameters that precede \p Param in the template parameter list.
5057 /// \returns the substituted template argument, or NULL if an error occurred.
5058 static TypeSourceInfo *
5060  TemplateDecl *Template,
5061  SourceLocation TemplateLoc,
5062  SourceLocation RAngleLoc,
5063  TemplateTypeParmDecl *Param,
5064  SmallVectorImpl<TemplateArgument> &Converted) {
5065  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
5066 
5067  // If the argument type is dependent, instantiate it now based
5068  // on the previously-computed template arguments.
5069  if (ArgType->getType()->isInstantiationDependentType()) {
5070  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5071  Param, Template, Converted,
5072  SourceRange(TemplateLoc, RAngleLoc));
5073  if (Inst.isInvalid())
5074  return nullptr;
5075 
5076  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5077 
5078  // Only substitute for the innermost template argument list.
5079  MultiLevelTemplateArgumentList TemplateArgLists;
5080  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5081  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5082  TemplateArgLists.addOuterTemplateArguments(None);
5083 
5084  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5085  ArgType =
5086  SemaRef.SubstType(ArgType, TemplateArgLists,
5087  Param->getDefaultArgumentLoc(), Param->getDeclName());
5088  }
5089 
5090  return ArgType;
5091 }
5092 
5093 /// Substitute template arguments into the default template argument for
5094 /// the given non-type template parameter.
5095 ///
5096 /// \param SemaRef the semantic analysis object for which we are performing
5097 /// the substitution.
5098 ///
5099 /// \param Template the template that we are synthesizing template arguments
5100 /// for.
5101 ///
5102 /// \param TemplateLoc the location of the template name that started the
5103 /// template-id we are checking.
5104 ///
5105 /// \param RAngleLoc the location of the right angle bracket ('>') that
5106 /// terminates the template-id.
5107 ///
5108 /// \param Param the non-type template parameter whose default we are
5109 /// substituting into.
5110 ///
5111 /// \param Converted the list of template arguments provided for template
5112 /// parameters that precede \p Param in the template parameter list.
5113 ///
5114 /// \returns the substituted template argument, or NULL if an error occurred.
5115 static ExprResult
5117  TemplateDecl *Template,
5118  SourceLocation TemplateLoc,
5119  SourceLocation RAngleLoc,
5120  NonTypeTemplateParmDecl *Param,
5121  SmallVectorImpl<TemplateArgument> &Converted) {
5122  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5123  Param, Template, Converted,
5124  SourceRange(TemplateLoc, RAngleLoc));
5125  if (Inst.isInvalid())
5126  return ExprError();
5127 
5128  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5129 
5130  // Only substitute for the innermost template argument list.
5131  MultiLevelTemplateArgumentList TemplateArgLists;
5132  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5133  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5134  TemplateArgLists.addOuterTemplateArguments(None);
5135 
5136  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5137  EnterExpressionEvaluationContext ConstantEvaluated(
5139  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
5140 }
5141 
5142 /// Substitute template arguments into the default template argument for
5143 /// the given template template parameter.
5144 ///
5145 /// \param SemaRef the semantic analysis object for which we are performing
5146 /// the substitution.
5147 ///
5148 /// \param Template the template that we are synthesizing template arguments
5149 /// for.
5150 ///
5151 /// \param TemplateLoc the location of the template name that started the
5152 /// template-id we are checking.
5153 ///
5154 /// \param RAngleLoc the location of the right angle bracket ('>') that
5155 /// terminates the template-id.
5156 ///
5157 /// \param Param the template template parameter whose default we are
5158 /// substituting into.
5159 ///
5160 /// \param Converted the list of template arguments provided for template
5161 /// parameters that precede \p Param in the template parameter list.
5162 ///
5163 /// \param QualifierLoc Will be set to the nested-name-specifier (with
5164 /// source-location information) that precedes the template name.
5165 ///
5166 /// \returns the substituted template argument, or NULL if an error occurred.
5167 static TemplateName
5169  TemplateDecl *Template,
5170  SourceLocation TemplateLoc,
5171  SourceLocation RAngleLoc,
5172  TemplateTemplateParmDecl *Param,
5174  NestedNameSpecifierLoc &QualifierLoc) {
5176  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
5177  SourceRange(TemplateLoc, RAngleLoc));
5178  if (Inst.isInvalid())
5179  return TemplateName();
5180 
5181  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5182 
5183  // Only substitute for the innermost template argument list.
5184  MultiLevelTemplateArgumentList TemplateArgLists;
5185  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5186  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5187  TemplateArgLists.addOuterTemplateArguments(None);
5188 
5189  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5190  // Substitute into the nested-name-specifier first,
5191  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
5192  if (QualifierLoc) {
5193  QualifierLoc =
5194  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
5195  if (!QualifierLoc)
5196  return TemplateName();
5197  }
5198 
5199  return SemaRef.SubstTemplateName(
5200  QualifierLoc,
5203  TemplateArgLists);
5204 }
5205 
5206 /// If the given template parameter has a default template
5207 /// argument, substitute into that default template argument and
5208 /// return the corresponding template argument.
5211  SourceLocation TemplateLoc,
5212  SourceLocation RAngleLoc,
5213  Decl *Param,
5215  &Converted,
5216  bool &HasDefaultArg) {
5217  HasDefaultArg = false;
5218 
5219  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
5220  if (!hasVisibleDefaultArgument(TypeParm))
5221  return TemplateArgumentLoc();
5222 
5223  HasDefaultArg = true;
5224  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
5225  TemplateLoc,
5226  RAngleLoc,
5227  TypeParm,
5228  Converted);
5229  if (DI)
5230  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
5231 
5232  return TemplateArgumentLoc();
5233  }
5234 
5235  if (NonTypeTemplateParmDecl *NonTypeParm
5236  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5237  if (!hasVisibleDefaultArgument(NonTypeParm))
5238  return TemplateArgumentLoc();
5239 
5240  HasDefaultArg = true;
5241  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
5242  TemplateLoc,
5243  RAngleLoc,
5244  NonTypeParm,
5245  Converted);
5246  if (Arg.isInvalid())
5247  return TemplateArgumentLoc();
5248 
5249  Expr *ArgE = Arg.getAs<Expr>();
5250  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
5251  }
5252 
5253  TemplateTemplateParmDecl *TempTempParm
5254  = cast<TemplateTemplateParmDecl>(Param);
5255  if (!hasVisibleDefaultArgument(TempTempParm))
5256  return TemplateArgumentLoc();
5257 
5258  HasDefaultArg = true;
5259  NestedNameSpecifierLoc QualifierLoc;
5260  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
5261  TemplateLoc,
5262  RAngleLoc,
5263  TempTempParm,
5264  Converted,
5265  QualifierLoc);
5266  if (TName.isNull())
5267  return TemplateArgumentLoc();
5268 
5269  return TemplateArgumentLoc(
5270  Context, TemplateArgument(TName),
5271  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
5272  TempTempParm->getDefaultArgument().getTemplateNameLoc());
5273 }
5274 
5275 /// Convert a template-argument that we parsed as a type into a template, if
5276 /// possible. C++ permits injected-class-names to perform dual service as
5277 /// template template arguments and as template type arguments.
5278 static TemplateArgumentLoc
5280  // Extract and step over any surrounding nested-name-specifier.
5281  NestedNameSpecifierLoc QualLoc;
5282  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
5283  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
5284  return TemplateArgumentLoc();
5285 
5286  QualLoc = ETLoc.getQualifierLoc();
5287  TLoc = ETLoc.getNamedTypeLoc();
5288  }
5289  // If this type was written as an injected-class-name, it can be used as a
5290  // template template argument.
5291  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
5292  return TemplateArgumentLoc(Context, InjLoc.getTypePtr()->getTemplateName(),
5293  QualLoc, InjLoc.getNameLoc());
5294 
5295  // If this type was written as an injected-class-name, it may have been
5296  // converted to a RecordType during instantiation. If the RecordType is
5297  // *not* wrapped in a TemplateSpecializationType and denotes a class
5298  // template specialization, it must have come from an injected-class-name.
5299  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
5300  if (auto *CTSD =
5301  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
5302  return TemplateArgumentLoc(Context,
5303  TemplateName(CTSD->getSpecializedTemplate()),
5304  QualLoc, RecLoc.getNameLoc());
5305 
5306  return TemplateArgumentLoc();
5307 }
5308 
5309 /// Check that the given template argument corresponds to the given
5310 /// template parameter.
5311 ///
5312 /// \param Param The template parameter against which the argument will be
5313 /// checked.
5314 ///
5315 /// \param Arg The template argument, which may be updated due to conversions.
5316 ///
5317 /// \param Template The template in which the template argument resides.
5318 ///
5319 /// \param TemplateLoc The location of the template name for the template
5320 /// whose argument list we're matching.
5321 ///
5322 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
5323 /// the template argument list.
5324 ///
5325 /// \param ArgumentPackIndex The index into the argument pack where this
5326 /// argument will be placed. Only valid if the parameter is a parameter pack.
5327 ///
5328 /// \param Converted The checked, converted argument will be added to the
5329 /// end of this small vector.
5330 ///
5331 /// \param CTAK Describes how we arrived at this particular template argument:
5332 /// explicitly written, deduced, etc.
5333 ///
5334 /// \returns true on error, false otherwise.
5336  TemplateArgumentLoc &Arg,
5337  NamedDecl *Template,
5338  SourceLocation TemplateLoc,
5339  SourceLocation RAngleLoc,
5340  unsigned ArgumentPackIndex,
5343  // Check template type parameters.
5344  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
5345  return CheckTemplateTypeArgument(TTP, Arg, Converted);
5346 
5347  // Check non-type template parameters.
5348  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5349  // Do substitution on the type of the non-type template parameter
5350  // with the template arguments we've seen thus far. But if the
5351  // template has a dependent context then we cannot substitute yet.
5352  QualType NTTPType = NTTP->getType();
5353  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
5354  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
5355 
5356  if (NTTPType->isInstantiationDependentType() &&
5357  !isa<TemplateTemplateParmDecl>(Template) &&
5358  !Template->getDeclContext()->isDependentContext()) {
5359  // Do substitution on the type of the non-type template parameter.
5360  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5361  NTTP, Converted,
5362  SourceRange(TemplateLoc, RAngleLoc));
5363  if (Inst.isInvalid())
5364  return true;
5365 
5367  Converted);
5368 
5369  // If the parameter is a pack expansion, expand this slice of the pack.
5370  if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
5371  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
5372  ArgumentPackIndex);
5373  NTTPType = SubstType(PET->getPattern(),
5374  MultiLevelTemplateArgumentList(TemplateArgs),
5375  NTTP->getLocation(),
5376  NTTP->getDeclName());
5377  } else {
5378  NTTPType = SubstType(NTTPType,
5379  MultiLevelTemplateArgumentList(TemplateArgs),
5380  NTTP->getLocation(),
5381  NTTP->getDeclName());
5382  }
5383 
5384  // If that worked, check the non-type template parameter type
5385  // for validity.
5386  if (!NTTPType.isNull())
5387  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
5388  NTTP->getLocation());
5389  if (NTTPType.isNull())
5390  return true;
5391  }
5392 
5393  switch (Arg.getArgument().getKind()) {
5395  llvm_unreachable("Should never see a NULL template argument here");
5396 
5398  TemplateArgument Result;
5399  unsigned CurSFINAEErrors = NumSFINAEErrors;
5400  ExprResult Res =
5401  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
5402  Result, CTAK);
5403  if (Res.isInvalid())
5404  return true;
5405  // If the current template argument causes an error, give up now.
5406  if (CurSFINAEErrors < NumSFINAEErrors)
5407  return true;
5408 
5409  // If the resulting expression is new, then use it in place of the
5410  // old expression in the template argument.
5411  if (Res.get() != Arg.getArgument().getAsExpr()) {
5412  TemplateArgument TA(Res.get());
5413  Arg = TemplateArgumentLoc(TA, Res.get());
5414  }
5415 
5416  Converted.push_back(Result);
5417  break;
5418  }
5419 
5423  // We've already checked this template argument, so just copy
5424  // it to the list of converted arguments.
5425  Converted.push_back(Arg.getArgument());
5426  break;
5427 
5430  // We were given a template template argument. It may not be ill-formed;
5431  // see below.
5432  if (DependentTemplateName *DTN
5435  // We have a template argument such as \c T::template X, which we
5436  // parsed as a template template argument. However, since we now
5437  // know that we need a non-type template argument, convert this
5438  // template name into an expression.
5439 
5440  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
5441  Arg.getTemplateNameLoc());
5442 
5443  CXXScopeSpec SS;
5444  SS.Adopt(Arg.getTemplateQualifierLoc());
5445  // FIXME: the template-template arg was a DependentTemplateName,
5446  // so it was provided with a template keyword. However, its source
5447  // location is not stored in the template argument structure.
5448  SourceLocation TemplateKWLoc;
5450  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
5451  nullptr);
5452 
5453  // If we parsed the template argument as a pack expansion, create a
5454  // pack expansion expression.
5456  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
5457  if (E.isInvalid())
5458  return true;
5459  }
5460 
5461  TemplateArgument Result;
5462  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
5463  if (E.isInvalid())
5464  return true;
5465 
5466  Converted.push_back(Result);
5467  break;
5468  }
5469 
5470  // We have a template argument that actually does refer to a class
5471  // template, alias template, or template template parameter, and
5472  // therefore cannot be a non-type template argument.
5473  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
5474  << Arg.getSourceRange();
5475 
5476  Diag(Param->getLocation(), diag::note_template_param_here);
5477  return true;
5478 
5479  case TemplateArgument::Type: {
5480  // We have a non-type template parameter but the template
5481  // argument is a type.
5482 
5483  // C++ [temp.arg]p2:
5484  // In a template-argument, an ambiguity between a type-id and
5485  // an expression is resolved to a type-id, regardless of the
5486  // form of the corresponding template-parameter.
5487  //
5488  // We warn specifically about this case, since it can be rather
5489  // confusing for users.
5490  QualType T = Arg.getArgument().getAsType();
5491  SourceRange SR = Arg.getSourceRange();
5492  if (T->isFunctionType())
5493  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
5494  else
5495  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
5496  Diag(Param->getLocation(), diag::note_template_param_here);
5497  return true;
5498  }
5499 
5501  llvm_unreachable("Caller must expand template argument packs");
5502  }
5503 
5504  return false;
5505  }
5506 
5507 
5508  // Check template template parameters.
5509  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
5510 
5511  TemplateParameterList *Params = TempParm->getTemplateParameters();
5512  if (TempParm->isExpandedParameterPack())
5513  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
5514 
5515  // Substitute into the template parameter list of the template
5516  // template parameter, since previously-supplied template arguments
5517  // may appear within the template template parameter.
5518  //
5519  // FIXME: Skip this if the parameters aren't instantiation-dependent.
5520  {
5521  // Set up a template instantiation context.
5523  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5524  TempParm, Converted,
5525  SourceRange(TemplateLoc, RAngleLoc));
5526  if (Inst.isInvalid())
5527  return true;
5528 
5529  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5530  Params = SubstTemplateParams(Params, CurContext,
5531  MultiLevelTemplateArgumentList(TemplateArgs));
5532  if (!Params)
5533  return true;
5534  }
5535 
5536  // C++1z [temp.local]p1: (DR1004)
5537  // When [the injected-class-name] is used [...] as a template-argument for
5538  // a template template-parameter [...] it refers to the class template
5539  // itself.
5540  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
5542  Context, Arg.getTypeSourceInfo()->getTypeLoc());
5543  if (!ConvertedArg.getArgument().isNull())
5544  Arg = ConvertedArg;
5545  }
5546 
5547  switch (Arg.getArgument().getKind()) {
5549  llvm_unreachable("Should never see a NULL template argument here");
5550 
5553  if (CheckTemplateTemplateArgument(TempParm, Params, Arg))
5554  return true;
5555 
5556  Converted.push_back(Arg.getArgument());
5557  break;
5558 
5561  // We have a template template parameter but the template
5562  // argument does not refer to a template.
5563  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
5564  << getLangOpts().CPlusPlus11;
5565  return true;
5566 
5568  llvm_unreachable("Declaration argument with template template parameter");
5570  llvm_unreachable("Integral argument with template template parameter");
5572  llvm_unreachable("Null pointer argument with template template parameter");
5573 
5575  llvm_unreachable("Caller must expand template argument packs");
5576  }
5577 
5578  return false;
5579 }
5580 
5581 /// Diagnose a missing template argument.
5582 template<typename TemplateParmDecl>
5584  TemplateDecl *TD,
5585  const TemplateParmDecl *D,
5586  TemplateArgumentListInfo &Args) {
5587  // Dig out the most recent declaration of the template parameter; there may be
5588  // declarations of the template that are more recent than TD.
5589  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
5590  ->getTemplateParameters()
5591  ->getParam(D->getIndex()));
5592 
5593  // If there's a default argument that's not visible, diagnose that we're
5594  // missing a module import.
5596  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5597  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5598  D->getDefaultArgumentLoc(), Modules,
5600  /*Recover*/true);
5601  return true;
5602  }
5603 
5604  // FIXME: If there's a more recent default argument that *is* visible,
5605  // diagnose that it was declared too late.
5606 
5608 
5609  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5610  << /*not enough args*/0
5612  << TD;
5613  S.Diag(TD->getLocation(), diag::note_template_decl_here)
5614  << Params->getSourceRange();
5615  return true;
5616 }
5617 
5618 /// Check that the given template argument list is well-formed
5619 /// for specializing the given template.
5621  TemplateDecl *Template, SourceLocation TemplateLoc,
5622  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
5624  bool UpdateArgsWithConversions, bool *ConstraintsNotSatisfied) {
5625 
5626  if (ConstraintsNotSatisfied)
5627  *ConstraintsNotSatisfied = false;
5628 
5629  // Make a copy of the template arguments for processing. Only make the
5630  // changes at the end when successful in matching the arguments to the
5631  // template.
5632  TemplateArgumentListInfo NewArgs = TemplateArgs;
5633 
5634  // Make sure we get the template parameter list from the most
5635  // recentdeclaration, since that is the only one that has is guaranteed to
5636  // have all the default template argument information.
5637  TemplateParameterList *Params =
5638  cast<TemplateDecl>(Template->getMostRecentDecl())
5639  ->getTemplateParameters();
5640 
5641  SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
5642 
5643  // C++ [temp.arg]p1:
5644  // [...] The type and form of each template-argument specified in
5645  // a template-id shall match the type and form specified for the
5646  // corresponding parameter declared by the template in its
5647  // template-parameter-list.
5648  bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
5649  SmallVector<TemplateArgument, 2> ArgumentPack;
5650  unsigned ArgIdx = 0, NumArgs = NewArgs.size();
5651  LocalInstantiationScope InstScope(*this, true);
5652  for (TemplateParameterList::iterator Param = Params->begin(),
5653  ParamEnd = Params->end();
5654  Param != ParamEnd; /* increment in loop */) {
5655  // If we have an expanded parameter pack, make sure we don't have too
5656  // many arguments.
5657  if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
5658  if (*Expansions == ArgumentPack.size()) {
5659  // We're done with this parameter pack. Pack up its arguments and add
5660  // them to the list.
5661  Converted.push_back(
5662  TemplateArgument::CreatePackCopy(Context, ArgumentPack));
5663  ArgumentPack.clear();
5664 
5665  // This argument is assigned to the next parameter.
5666  ++Param;
5667  continue;
5668  } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
5669  // Not enough arguments for this parameter pack.
5670  Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
5671  << /*not enough args*/0
5672  << (int)getTemplateNameKindForDiagnostics(TemplateName(Template))
5673  << Template;
5674  Diag(Template->getLocation(), diag::note_template_decl_here)
5675  << Params->getSourceRange();
5676  return true;
5677  }
5678  }
5679 
5680  if (ArgIdx < NumArgs) {
5681  // Check the template argument we were given.
5682  if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
5683  TemplateLoc, RAngleLoc,
5684  ArgumentPack.size(), Converted))
5685  return true;
5686 
5687  bool PackExpansionIntoNonPack =
5688  NewArgs[ArgIdx].getArgument().isPackExpansion() &&
5689  (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
5690  if (PackExpansionIntoNonPack && (isa<TypeAliasTemplateDecl>(Template) ||
5691  isa<ConceptDecl>(Template))) {
5692  // Core issue 1430: we have a pack expansion as an argument to an
5693  // alias template, and it's not part of a parameter pack. This
5694  // can't be canonicalized, so reject it now.
5695  // As for concepts - we cannot normalize constraints where this
5696  // situation exists.
5697  Diag(NewArgs[ArgIdx].getLocation(),
5698  diag::err_template_expansion_into_fixed_list)
5699  << (isa<ConceptDecl>(Template) ? 1 : 0)
5700  << NewArgs[ArgIdx].getSourceRange();
5701  Diag((*Param)->getLocation(), diag::note_template_param_here);
5702  return true;