clang  13.0.0git
SemaTemplate.cpp
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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //===----------------------------------------------------------------------===//
7 //
8 // This file implements semantic analysis for C++ templates.
9 //===----------------------------------------------------------------------===//
10 
11 #include "TreeTransform.h"
12 #include "clang/AST/ASTConsumer.h"
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/DeclFriend.h"
15 #include "clang/AST/DeclTemplate.h"
16 #include "clang/AST/Expr.h"
17 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/TypeVisitor.h"
20 #include "clang/Basic/Builtins.h"
23 #include "clang/Basic/Stack.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
27 #include "clang/Sema/Lookup.h"
28 #include "clang/Sema/Overload.h"
30 #include "clang/Sema/Scope.h"
32 #include "clang/Sema/Template.h"
34 #include "llvm/ADT/SmallBitVector.h"
35 #include "llvm/ADT/SmallString.h"
36 #include "llvm/ADT/StringExtras.h"
37 
38 #include <iterator>
39 using namespace clang;
40 using namespace sema;
41 
42 // Exported for use by Parser.
45  unsigned N) {
46  if (!N) return SourceRange();
47  return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
48 }
49 
50 unsigned Sema::getTemplateDepth(Scope *S) const {
51  unsigned Depth = 0;
52 
53  // Each template parameter scope represents one level of template parameter
54  // depth.
55  for (Scope *TempParamScope = S->getTemplateParamParent(); TempParamScope;
56  TempParamScope = TempParamScope->getParent()->getTemplateParamParent()) {
57  ++Depth;
58  }
59 
60  // Note that there are template parameters with the given depth.
61  auto ParamsAtDepth = [&](unsigned D) { Depth = std::max(Depth, D + 1); };
62 
63  // Look for parameters of an enclosing generic lambda. We don't create a
64  // template parameter scope for these.
65  for (FunctionScopeInfo *FSI : getFunctionScopes()) {
66  if (auto *LSI = dyn_cast<LambdaScopeInfo>(FSI)) {
67  if (!LSI->TemplateParams.empty()) {
68  ParamsAtDepth(LSI->AutoTemplateParameterDepth);
69  break;
70  }
71  if (LSI->GLTemplateParameterList) {
72  ParamsAtDepth(LSI->GLTemplateParameterList->getDepth());
73  break;
74  }
75  }
76  }
77 
78  // Look for parameters of an enclosing terse function template. We don't
79  // create a template parameter scope for these either.
80  for (const InventedTemplateParameterInfo &Info :
81  getInventedParameterInfos()) {
82  if (!Info.TemplateParams.empty()) {
83  ParamsAtDepth(Info.AutoTemplateParameterDepth);
84  break;
85  }
86  }
87 
88  return Depth;
89 }
90 
91 /// \brief Determine whether the declaration found is acceptable as the name
92 /// of a template and, if so, return that template declaration. Otherwise,
93 /// returns null.
94 ///
95 /// Note that this may return an UnresolvedUsingValueDecl if AllowDependent
96 /// is true. In all other cases it will return a TemplateDecl (or null).
98  bool AllowFunctionTemplates,
99  bool AllowDependent) {
100  D = D->getUnderlyingDecl();
101 
102  if (isa<TemplateDecl>(D)) {
103  if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
104  return nullptr;
105 
106  return D;
107  }
108 
109  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
110  // C++ [temp.local]p1:
111  // Like normal (non-template) classes, class templates have an
112  // injected-class-name (Clause 9). The injected-class-name
113  // can be used with or without a template-argument-list. When
114  // it is used without a template-argument-list, it is
115  // equivalent to the injected-class-name followed by the
116  // template-parameters of the class template enclosed in
117  // <>. When it is used with a template-argument-list, it
118  // refers to the specified class template specialization,
119  // which could be the current specialization or another
120  // specialization.
121  if (Record->isInjectedClassName()) {
122  Record = cast<CXXRecordDecl>(Record->getDeclContext());
123  if (Record->getDescribedClassTemplate())
124  return Record->getDescribedClassTemplate();
125 
127  = dyn_cast<ClassTemplateSpecializationDecl>(Record))
128  return Spec->getSpecializedTemplate();
129  }
130 
131  return nullptr;
132  }
133 
134  // 'using Dependent::foo;' can resolve to a template name.
135  // 'using typename Dependent::foo;' cannot (not even if 'foo' is an
136  // injected-class-name).
137  if (AllowDependent && isa<UnresolvedUsingValueDecl>(D))
138  return D;
139 
140  return nullptr;
141 }
142 
144  bool AllowFunctionTemplates,
145  bool AllowDependent) {
146  LookupResult::Filter filter = R.makeFilter();
147  while (filter.hasNext()) {
148  NamedDecl *Orig = filter.next();
149  if (!getAsTemplateNameDecl(Orig, AllowFunctionTemplates, AllowDependent))
150  filter.erase();
151  }
152  filter.done();
153 }
154 
156  bool AllowFunctionTemplates,
157  bool AllowDependent,
158  bool AllowNonTemplateFunctions) {
159  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
160  if (getAsTemplateNameDecl(*I, AllowFunctionTemplates, AllowDependent))
161  return true;
162  if (AllowNonTemplateFunctions &&
163  isa<FunctionDecl>((*I)->getUnderlyingDecl()))
164  return true;
165  }
166 
167  return false;
168 }
169 
171  CXXScopeSpec &SS,
172  bool hasTemplateKeyword,
173  const UnqualifiedId &Name,
174  ParsedType ObjectTypePtr,
175  bool EnteringContext,
176  TemplateTy &TemplateResult,
177  bool &MemberOfUnknownSpecialization,
178  bool Disambiguation) {
179  assert(getLangOpts().CPlusPlus && "No template names in C!");
180 
181  DeclarationName TName;
182  MemberOfUnknownSpecialization = false;
183 
184  switch (Name.getKind()) {
186  TName = DeclarationName(Name.Identifier);
187  break;
188 
190  TName = Context.DeclarationNames.getCXXOperatorName(
191  Name.OperatorFunctionId.Operator);
192  break;
193 
195  TName = Context.DeclarationNames.getCXXLiteralOperatorName(Name.Identifier);
196  break;
197 
198  default:
199  return TNK_Non_template;
200  }
201 
202  QualType ObjectType = ObjectTypePtr.get();
203 
204  AssumedTemplateKind AssumedTemplate;
205  LookupResult R(*this, TName, Name.getBeginLoc(), LookupOrdinaryName);
206  if (LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
207  MemberOfUnknownSpecialization, SourceLocation(),
208  &AssumedTemplate,
209  /*AllowTypoCorrection=*/!Disambiguation))
210  return TNK_Non_template;
211 
212  if (AssumedTemplate != AssumedTemplateKind::None) {
213  TemplateResult = TemplateTy::make(Context.getAssumedTemplateName(TName));
214  // Let the parser know whether we found nothing or found functions; if we
215  // found nothing, we want to more carefully check whether this is actually
216  // a function template name versus some other kind of undeclared identifier.
217  return AssumedTemplate == AssumedTemplateKind::FoundNothing
220  }
221 
222  if (R.empty())
223  return TNK_Non_template;
224 
225  NamedDecl *D = nullptr;
226  if (R.isAmbiguous()) {
227  // If we got an ambiguity involving a non-function template, treat this
228  // as a template name, and pick an arbitrary template for error recovery.
229  bool AnyFunctionTemplates = false;
230  for (NamedDecl *FoundD : R) {
231  if (NamedDecl *FoundTemplate = getAsTemplateNameDecl(FoundD)) {
232  if (isa<FunctionTemplateDecl>(FoundTemplate))
233  AnyFunctionTemplates = true;
234  else {
235  D = FoundTemplate;
236  break;
237  }
238  }
239  }
240 
241  // If we didn't find any templates at all, this isn't a template name.
242  // Leave the ambiguity for a later lookup to diagnose.
243  if (!D && !AnyFunctionTemplates) {
244  R.suppressDiagnostics();
245  return TNK_Non_template;
246  }
247 
248  // If the only templates were function templates, filter out the rest.
249  // We'll diagnose the ambiguity later.
250  if (!D)
251  FilterAcceptableTemplateNames(R);
252  }
253 
254  // At this point, we have either picked a single template name declaration D
255  // or we have a non-empty set of results R containing either one template name
256  // declaration or a set of function templates.
257 
258  TemplateName Template;
259  TemplateNameKind TemplateKind;
260 
261  unsigned ResultCount = R.end() - R.begin();
262  if (!D && ResultCount > 1) {
263  // We assume that we'll preserve the qualifier from a function
264  // template name in other ways.
265  Template = Context.getOverloadedTemplateName(R.begin(), R.end());
266  TemplateKind = TNK_Function_template;
267 
268  // We'll do this lookup again later.
270  } else {
271  if (!D) {
272  D = getAsTemplateNameDecl(*R.begin());
273  assert(D && "unambiguous result is not a template name");
274  }
275 
276  if (isa<UnresolvedUsingValueDecl>(D)) {
277  // We don't yet know whether this is a template-name or not.
278  MemberOfUnknownSpecialization = true;
279  return TNK_Non_template;
280  }
281 
282  TemplateDecl *TD = cast<TemplateDecl>(D);
283 
284  if (SS.isSet() && !SS.isInvalid()) {
285  NestedNameSpecifier *Qualifier = SS.getScopeRep();
286  Template = Context.getQualifiedTemplateName(Qualifier,
287  hasTemplateKeyword, TD);
288  } else {
289  Template = TemplateName(TD);
290  }
291 
292  if (isa<FunctionTemplateDecl>(TD)) {
293  TemplateKind = TNK_Function_template;
294 
295  // We'll do this lookup again later.
297  } else {
298  assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
299  isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
300  isa<BuiltinTemplateDecl>(TD) || isa<ConceptDecl>(TD));
301  TemplateKind =
302  isa<VarTemplateDecl>(TD) ? TNK_Var_template :
303  isa<ConceptDecl>(TD) ? TNK_Concept_template :
305  }
306  }
307 
308  TemplateResult = TemplateTy::make(Template);
309  return TemplateKind;
310 }
311 
313  SourceLocation NameLoc,
314  ParsedTemplateTy *Template) {
315  CXXScopeSpec SS;
316  bool MemberOfUnknownSpecialization = false;
317 
318  // We could use redeclaration lookup here, but we don't need to: the
319  // syntactic form of a deduction guide is enough to identify it even
320  // if we can't look up the template name at all.
321  LookupResult R(*this, DeclarationName(&Name), NameLoc, LookupOrdinaryName);
322  if (LookupTemplateName(R, S, SS, /*ObjectType*/ QualType(),
323  /*EnteringContext*/ false,
324  MemberOfUnknownSpecialization))
325  return false;
326 
327  if (R.empty()) return false;
328  if (R.isAmbiguous()) {
329  // FIXME: Diagnose an ambiguity if we find at least one template.
331  return false;
332  }
333 
334  // We only treat template-names that name type templates as valid deduction
335  // guide names.
337  if (!TD || !getAsTypeTemplateDecl(TD))
338  return false;
339 
340  if (Template)
341  *Template = TemplateTy::make(TemplateName(TD));
342  return true;
343 }
344 
346  SourceLocation IILoc,
347  Scope *S,
348  const CXXScopeSpec *SS,
349  TemplateTy &SuggestedTemplate,
350  TemplateNameKind &SuggestedKind) {
351  // We can't recover unless there's a dependent scope specifier preceding the
352  // template name.
353  // FIXME: Typo correction?
354  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
355  computeDeclContext(*SS))
356  return false;
357 
358  // The code is missing a 'template' keyword prior to the dependent template
359  // name.
361  Diag(IILoc, diag::err_template_kw_missing)
362  << Qualifier << II.getName()
363  << FixItHint::CreateInsertion(IILoc, "template ");
364  SuggestedTemplate
365  = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
366  SuggestedKind = TNK_Dependent_template_name;
367  return true;
368 }
369 
371  Scope *S, CXXScopeSpec &SS,
372  QualType ObjectType,
373  bool EnteringContext,
374  bool &MemberOfUnknownSpecialization,
375  RequiredTemplateKind RequiredTemplate,
376  AssumedTemplateKind *ATK,
377  bool AllowTypoCorrection) {
378  if (ATK)
380 
381  if (SS.isInvalid())
382  return true;
383 
384  Found.setTemplateNameLookup(true);
385 
386  // Determine where to perform name lookup
387  MemberOfUnknownSpecialization = false;
388  DeclContext *LookupCtx = nullptr;
389  bool IsDependent = false;
390  if (!ObjectType.isNull()) {
391  // This nested-name-specifier occurs in a member access expression, e.g.,
392  // x->B::f, and we are looking into the type of the object.
393  assert(SS.isEmpty() && "ObjectType and scope specifier cannot coexist");
394  LookupCtx = computeDeclContext(ObjectType);
395  IsDependent = !LookupCtx && ObjectType->isDependentType();
396  assert((IsDependent || !ObjectType->isIncompleteType() ||
397  ObjectType->castAs<TagType>()->isBeingDefined()) &&
398  "Caller should have completed object type");
399 
400  // Template names cannot appear inside an Objective-C class or object type
401  // or a vector type.
402  //
403  // FIXME: This is wrong. For example:
404  //
405  // template<typename T> using Vec = T __attribute__((ext_vector_type(4)));
406  // Vec<int> vi;
407  // vi.Vec<int>::~Vec<int>();
408  //
409  // ... should be accepted but we will not treat 'Vec' as a template name
410  // here. The right thing to do would be to check if the name is a valid
411  // vector component name, and look up a template name if not. And similarly
412  // for lookups into Objective-C class and object types, where the same
413  // problem can arise.
414  if (ObjectType->isObjCObjectOrInterfaceType() ||
415  ObjectType->isVectorType()) {
416  Found.clear();
417  return false;
418  }
419  } else if (SS.isNotEmpty()) {
420  // This nested-name-specifier occurs after another nested-name-specifier,
421  // so long into the context associated with the prior nested-name-specifier.
422  LookupCtx = computeDeclContext(SS, EnteringContext);
423  IsDependent = !LookupCtx && isDependentScopeSpecifier(SS);
424 
425  // The declaration context must be complete.
426  if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
427  return true;
428  }
429 
430  bool ObjectTypeSearchedInScope = false;
431  bool AllowFunctionTemplatesInLookup = true;
432  if (LookupCtx) {
433  // Perform "qualified" name lookup into the declaration context we
434  // computed, which is either the type of the base of a member access
435  // expression or the declaration context associated with a prior
436  // nested-name-specifier.
437  LookupQualifiedName(Found, LookupCtx);
438 
439  // FIXME: The C++ standard does not clearly specify what happens in the
440  // case where the object type is dependent, and implementations vary. In
441  // Clang, we treat a name after a . or -> as a template-name if lookup
442  // finds a non-dependent member or member of the current instantiation that
443  // is a type template, or finds no such members and lookup in the context
444  // of the postfix-expression finds a type template. In the latter case, the
445  // name is nonetheless dependent, and we may resolve it to a member of an
446  // unknown specialization when we come to instantiate the template.
447  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
448  }
449 
450  if (SS.isEmpty() && (ObjectType.isNull() || Found.empty())) {
451  // C++ [basic.lookup.classref]p1:
452  // In a class member access expression (5.2.5), if the . or -> token is
453  // immediately followed by an identifier followed by a <, the
454  // identifier must be looked up to determine whether the < is the
455  // beginning of a template argument list (14.2) or a less-than operator.
456  // The identifier is first looked up in the class of the object
457  // expression. If the identifier is not found, it is then looked up in
458  // the context of the entire postfix-expression and shall name a class
459  // template.
460  if (S)
461  LookupName(Found, S);
462 
463  if (!ObjectType.isNull()) {
464  // FIXME: We should filter out all non-type templates here, particularly
465  // variable templates and concepts. But the exclusion of alias templates
466  // and template template parameters is a wording defect.
467  AllowFunctionTemplatesInLookup = false;
468  ObjectTypeSearchedInScope = true;
469  }
470 
471  IsDependent |= Found.wasNotFoundInCurrentInstantiation();
472  }
473 
474  if (Found.isAmbiguous())
475  return false;
476 
477  if (ATK && SS.isEmpty() && ObjectType.isNull() &&
478  !RequiredTemplate.hasTemplateKeyword()) {
479  // C++2a [temp.names]p2:
480  // A name is also considered to refer to a template if it is an
481  // unqualified-id followed by a < and name lookup finds either one or more
482  // functions or finds nothing.
483  //
484  // To keep our behavior consistent, we apply the "finds nothing" part in
485  // all language modes, and diagnose the empty lookup in ActOnCallExpr if we
486  // successfully form a call to an undeclared template-id.
487  bool AllFunctions =
488  getLangOpts().CPlusPlus20 &&
489  std::all_of(Found.begin(), Found.end(), [](NamedDecl *ND) {
490  return isa<FunctionDecl>(ND->getUnderlyingDecl());
491  });
492  if (AllFunctions || (Found.empty() && !IsDependent)) {
493  // If lookup found any functions, or if this is a name that can only be
494  // used for a function, then strongly assume this is a function
495  // template-id.
496  *ATK = (Found.empty() && Found.getLookupName().isIdentifier())
497  ? AssumedTemplateKind::FoundNothing
498  : AssumedTemplateKind::FoundFunctions;
499  Found.clear();
500  return false;
501  }
502  }
503 
504  if (Found.empty() && !IsDependent && AllowTypoCorrection) {
505  // If we did not find any names, and this is not a disambiguation, attempt
506  // to correct any typos.
507  DeclarationName Name = Found.getLookupName();
508  Found.clear();
509  // Simple filter callback that, for keywords, only accepts the C++ *_cast
510  DefaultFilterCCC FilterCCC{};
511  FilterCCC.WantTypeSpecifiers = false;
512  FilterCCC.WantExpressionKeywords = false;
513  FilterCCC.WantRemainingKeywords = false;
514  FilterCCC.WantCXXNamedCasts = true;
515  if (TypoCorrection Corrected =
516  CorrectTypo(Found.getLookupNameInfo(), Found.getLookupKind(), S,
517  &SS, FilterCCC, CTK_ErrorRecovery, LookupCtx)) {
518  if (auto *ND = Corrected.getFoundDecl())
519  Found.addDecl(ND);
520  FilterAcceptableTemplateNames(Found);
521  if (Found.isAmbiguous()) {
522  Found.clear();
523  } else if (!Found.empty()) {
524  Found.setLookupName(Corrected.getCorrection());
525  if (LookupCtx) {
526  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
527  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
528  Name.getAsString() == CorrectedStr;
529  diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
530  << Name << LookupCtx << DroppedSpecifier
531  << SS.getRange());
532  } else {
533  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
534  }
535  }
536  }
537  }
538 
539  NamedDecl *ExampleLookupResult =
540  Found.empty() ? nullptr : Found.getRepresentativeDecl();
541  FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
542  if (Found.empty()) {
543  if (IsDependent) {
544  MemberOfUnknownSpecialization = true;
545  return false;
546  }
547 
548  // If a 'template' keyword was used, a lookup that finds only non-template
549  // names is an error.
550  if (ExampleLookupResult && RequiredTemplate) {
551  Diag(Found.getNameLoc(), diag::err_template_kw_refers_to_non_template)
552  << Found.getLookupName() << SS.getRange()
553  << RequiredTemplate.hasTemplateKeyword()
554  << RequiredTemplate.getTemplateKeywordLoc();
555  Diag(ExampleLookupResult->getUnderlyingDecl()->getLocation(),
556  diag::note_template_kw_refers_to_non_template)
557  << Found.getLookupName();
558  return true;
559  }
560 
561  return false;
562  }
563 
564  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
565  !getLangOpts().CPlusPlus11) {
566  // C++03 [basic.lookup.classref]p1:
567  // [...] If the lookup in the class of the object expression finds a
568  // template, the name is also looked up in the context of the entire
569  // postfix-expression and [...]
570  //
571  // Note: C++11 does not perform this second lookup.
572  LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
573  LookupOrdinaryName);
574  FoundOuter.setTemplateNameLookup(true);
575  LookupName(FoundOuter, S);
576  // FIXME: We silently accept an ambiguous lookup here, in violation of
577  // [basic.lookup]/1.
578  FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
579 
580  NamedDecl *OuterTemplate;
581  if (FoundOuter.empty()) {
582  // - if the name is not found, the name found in the class of the
583  // object expression is used, otherwise
584  } else if (FoundOuter.isAmbiguous() || !FoundOuter.isSingleResult() ||
585  !(OuterTemplate =
586  getAsTemplateNameDecl(FoundOuter.getFoundDecl()))) {
587  // - if the name is found in the context of the entire
588  // postfix-expression and does not name a class template, the name
589  // found in the class of the object expression is used, otherwise
590  FoundOuter.clear();
591  } else if (!Found.isSuppressingDiagnostics()) {
592  // - if the name found is a class template, it must refer to the same
593  // entity as the one found in the class of the object expression,
594  // otherwise the program is ill-formed.
595  if (!Found.isSingleResult() ||
596  getAsTemplateNameDecl(Found.getFoundDecl())->getCanonicalDecl() !=
597  OuterTemplate->getCanonicalDecl()) {
598  Diag(Found.getNameLoc(),
599  diag::ext_nested_name_member_ref_lookup_ambiguous)
600  << Found.getLookupName()
601  << ObjectType;
603  diag::note_ambig_member_ref_object_type)
604  << ObjectType;
605  Diag(FoundOuter.getFoundDecl()->getLocation(),
606  diag::note_ambig_member_ref_scope);
607 
608  // Recover by taking the template that we found in the object
609  // expression's type.
610  }
611  }
612  }
613 
614  return false;
615 }
616 
618  SourceLocation Less,
619  SourceLocation Greater) {
620  if (TemplateName.isInvalid())
621  return;
622 
623  DeclarationNameInfo NameInfo;
624  CXXScopeSpec SS;
625  LookupNameKind LookupKind;
626 
627  DeclContext *LookupCtx = nullptr;
628  NamedDecl *Found = nullptr;
629  bool MissingTemplateKeyword = false;
630 
631  // Figure out what name we looked up.
632  if (auto *DRE = dyn_cast<DeclRefExpr>(TemplateName.get())) {
633  NameInfo = DRE->getNameInfo();
634  SS.Adopt(DRE->getQualifierLoc());
635  LookupKind = LookupOrdinaryName;
636  Found = DRE->getFoundDecl();
637  } else if (auto *ME = dyn_cast<MemberExpr>(TemplateName.get())) {
638  NameInfo = ME->getMemberNameInfo();
639  SS.Adopt(ME->getQualifierLoc());
640  LookupKind = LookupMemberName;
641  LookupCtx = ME->getBase()->getType()->getAsCXXRecordDecl();
642  Found = ME->getMemberDecl();
643  } else if (auto *DSDRE =
644  dyn_cast<DependentScopeDeclRefExpr>(TemplateName.get())) {
645  NameInfo = DSDRE->getNameInfo();
646  SS.Adopt(DSDRE->getQualifierLoc());
647  MissingTemplateKeyword = true;
648  } else if (auto *DSME =
649  dyn_cast<CXXDependentScopeMemberExpr>(TemplateName.get())) {
650  NameInfo = DSME->getMemberNameInfo();
651  SS.Adopt(DSME->getQualifierLoc());
652  MissingTemplateKeyword = true;
653  } else {
654  llvm_unreachable("unexpected kind of potential template name");
655  }
656 
657  // If this is a dependent-scope lookup, diagnose that the 'template' keyword
658  // was missing.
659  if (MissingTemplateKeyword) {
660  Diag(NameInfo.getBeginLoc(), diag::err_template_kw_missing)
661  << "" << NameInfo.getName().getAsString() << SourceRange(Less, Greater);
662  return;
663  }
664 
665  // Try to correct the name by looking for templates and C++ named casts.
666  struct TemplateCandidateFilter : CorrectionCandidateCallback {
667  Sema &S;
668  TemplateCandidateFilter(Sema &S) : S(S) {
669  WantTypeSpecifiers = false;
670  WantExpressionKeywords = false;
671  WantRemainingKeywords = false;
672  WantCXXNamedCasts = true;
673  };
674  bool ValidateCandidate(const TypoCorrection &Candidate) override {
675  if (auto *ND = Candidate.getCorrectionDecl())
676  return S.getAsTemplateNameDecl(ND);
677  return Candidate.isKeyword();
678  }
679 
680  std::unique_ptr<CorrectionCandidateCallback> clone() override {
681  return std::make_unique<TemplateCandidateFilter>(*this);
682  }
683  };
684 
685  DeclarationName Name = NameInfo.getName();
686  TemplateCandidateFilter CCC(*this);
687  if (TypoCorrection Corrected = CorrectTypo(NameInfo, LookupKind, S, &SS, CCC,
688  CTK_ErrorRecovery, LookupCtx)) {
689  auto *ND = Corrected.getFoundDecl();
690  if (ND)
691  ND = getAsTemplateNameDecl(ND);
692  if (ND || Corrected.isKeyword()) {
693  if (LookupCtx) {
694  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
695  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
696  Name.getAsString() == CorrectedStr;
697  diagnoseTypo(Corrected,
698  PDiag(diag::err_non_template_in_member_template_id_suggest)
699  << Name << LookupCtx << DroppedSpecifier
700  << SS.getRange(), false);
701  } else {
702  diagnoseTypo(Corrected,
703  PDiag(diag::err_non_template_in_template_id_suggest)
704  << Name, false);
705  }
706  if (Found)
707  Diag(Found->getLocation(),
708  diag::note_non_template_in_template_id_found);
709  return;
710  }
711  }
712 
713  Diag(NameInfo.getLoc(), diag::err_non_template_in_template_id)
714  << Name << SourceRange(Less, Greater);
715  if (Found)
716  Diag(Found->getLocation(), diag::note_non_template_in_template_id_found);
717 }
718 
719 /// ActOnDependentIdExpression - Handle a dependent id-expression that
720 /// was just parsed. This is only possible with an explicit scope
721 /// specifier naming a dependent type.
724  SourceLocation TemplateKWLoc,
725  const DeclarationNameInfo &NameInfo,
726  bool isAddressOfOperand,
727  const TemplateArgumentListInfo *TemplateArgs) {
728  DeclContext *DC = getFunctionLevelDeclContext();
729 
730  // C++11 [expr.prim.general]p12:
731  // An id-expression that denotes a non-static data member or non-static
732  // member function of a class can only be used:
733  // (...)
734  // - if that id-expression denotes a non-static data member and it
735  // appears in an unevaluated operand.
736  //
737  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
738  // CXXDependentScopeMemberExpr. The former can instantiate to either
739  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
740  // always a MemberExpr.
741  bool MightBeCxx11UnevalField =
742  getLangOpts().CPlusPlus11 && isUnevaluatedContext();
743 
744  // Check if the nested name specifier is an enum type.
745  bool IsEnum = false;
746  if (NestedNameSpecifier *NNS = SS.getScopeRep())
747  IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
748 
749  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
750  isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
751  QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType();
752 
753  // Since the 'this' expression is synthesized, we don't need to
754  // perform the double-lookup check.
755  NamedDecl *FirstQualifierInScope = nullptr;
756 
758  Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
759  /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
760  FirstQualifierInScope, NameInfo, TemplateArgs);
761  }
762 
763  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
764 }
765 
768  SourceLocation TemplateKWLoc,
769  const DeclarationNameInfo &NameInfo,
770  const TemplateArgumentListInfo *TemplateArgs) {
771  // DependentScopeDeclRefExpr::Create requires a valid QualifierLoc
772  NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
773  if (!QualifierLoc)
774  return ExprError();
775 
777  Context, QualifierLoc, TemplateKWLoc, NameInfo, TemplateArgs);
778 }
779 
780 
781 /// Determine whether we would be unable to instantiate this template (because
782 /// it either has no definition, or is in the process of being instantiated).
784  NamedDecl *Instantiation,
785  bool InstantiatedFromMember,
786  const NamedDecl *Pattern,
787  const NamedDecl *PatternDef,
789  bool Complain /*= true*/) {
790  assert(isa<TagDecl>(Instantiation) || isa<FunctionDecl>(Instantiation) ||
791  isa<VarDecl>(Instantiation));
792 
793  bool IsEntityBeingDefined = false;
794  if (const TagDecl *TD = dyn_cast_or_null<TagDecl>(PatternDef))
795  IsEntityBeingDefined = TD->isBeingDefined();
796 
797  if (PatternDef && !IsEntityBeingDefined) {
798  NamedDecl *SuggestedDef = nullptr;
799  if (!hasVisibleDefinition(const_cast<NamedDecl*>(PatternDef), &SuggestedDef,
800  /*OnlyNeedComplete*/false)) {
801  // If we're allowed to diagnose this and recover, do so.
802  bool Recover = Complain && !isSFINAEContext();
803  if (Complain)
804  diagnoseMissingImport(PointOfInstantiation, SuggestedDef,
806  return !Recover;
807  }
808  return false;
809  }
810 
811  if (!Complain || (PatternDef && PatternDef->isInvalidDecl()))
812  return true;
813 
815  QualType InstantiationTy;
816  if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
817  InstantiationTy = Context.getTypeDeclType(TD);
818  if (PatternDef) {
819  Diag(PointOfInstantiation,
820  diag::err_template_instantiate_within_definition)
821  << /*implicit|explicit*/(TSK != TSK_ImplicitInstantiation)
822  << InstantiationTy;
823  // Not much point in noting the template declaration here, since
824  // we're lexically inside it.
825  Instantiation->setInvalidDecl();
826  } else if (InstantiatedFromMember) {
827  if (isa<FunctionDecl>(Instantiation)) {
828  Diag(PointOfInstantiation,
829  diag::err_explicit_instantiation_undefined_member)
830  << /*member function*/ 1 << Instantiation->getDeclName()
831  << Instantiation->getDeclContext();
832  Note = diag::note_explicit_instantiation_here;
833  } else {
834  assert(isa<TagDecl>(Instantiation) && "Must be a TagDecl!");
835  Diag(PointOfInstantiation,
836  diag::err_implicit_instantiate_member_undefined)
837  << InstantiationTy;
838  Note = diag::note_member_declared_at;
839  }
840  } else {
841  if (isa<FunctionDecl>(Instantiation)) {
842  Diag(PointOfInstantiation,
843  diag::err_explicit_instantiation_undefined_func_template)
844  << Pattern;
845  Note = diag::note_explicit_instantiation_here;
846  } else if (isa<TagDecl>(Instantiation)) {
847  Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
848  << (TSK != TSK_ImplicitInstantiation)
849  << InstantiationTy;
850  Note = diag::note_template_decl_here;
851  } else {
852  assert(isa<VarDecl>(Instantiation) && "Must be a VarDecl!");
853  if (isa<VarTemplateSpecializationDecl>(Instantiation)) {
854  Diag(PointOfInstantiation,
855  diag::err_explicit_instantiation_undefined_var_template)
856  << Instantiation;
857  Instantiation->setInvalidDecl();
858  } else
859  Diag(PointOfInstantiation,
860  diag::err_explicit_instantiation_undefined_member)
861  << /*static data member*/ 2 << Instantiation->getDeclName()
862  << Instantiation->getDeclContext();
863  Note = diag::note_explicit_instantiation_here;
864  }
865  }
866  if (Note) // Diagnostics were emitted.
867  Diag(Pattern->getLocation(), Note.getValue());
868 
869  // In general, Instantiation isn't marked invalid to get more than one
870  // error for multiple undefined instantiations. But the code that does
871  // explicit declaration -> explicit definition conversion can't handle
872  // invalid declarations, so mark as invalid in that case.
874  Instantiation->setInvalidDecl();
875  return true;
876 }
877 
878 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
879 /// that the template parameter 'PrevDecl' is being shadowed by a new
880 /// declaration at location Loc. Returns true to indicate that this is
881 /// an error, and false otherwise.
883  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
884 
885  // C++ [temp.local]p4:
886  // A template-parameter shall not be redeclared within its
887  // scope (including nested scopes).
888  //
889  // Make this a warning when MSVC compatibility is requested.
890  unsigned DiagId = getLangOpts().MSVCCompat ? diag::ext_template_param_shadow
891  : diag::err_template_param_shadow;
892  Diag(Loc, DiagId) << cast<NamedDecl>(PrevDecl)->getDeclName();
893  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
894 }
895 
896 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
897 /// the parameter D to reference the templated declaration and return a pointer
898 /// to the template declaration. Otherwise, do nothing to D and return null.
900  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
901  D = Temp->getTemplatedDecl();
902  return Temp;
903  }
904  return nullptr;
905 }
906 
908  SourceLocation EllipsisLoc) const {
909  assert(Kind == Template &&
910  "Only template template arguments can be pack expansions here");
911  assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
912  "Template template argument pack expansion without packs");
913  ParsedTemplateArgument Result(*this);
914  Result.EllipsisLoc = EllipsisLoc;
915  return Result;
916 }
917 
919  const ParsedTemplateArgument &Arg) {
920 
921  switch (Arg.getKind()) {
923  TypeSourceInfo *DI;
924  QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
925  if (!DI)
926  DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
927  return TemplateArgumentLoc(TemplateArgument(T), DI);
928  }
929 
931  Expr *E = static_cast<Expr *>(Arg.getAsExpr());
933  }
934 
936  TemplateName Template = Arg.getAsTemplate().get();
937  TemplateArgument TArg;
938  if (Arg.getEllipsisLoc().isValid())
939  TArg = TemplateArgument(Template, Optional<unsigned int>());
940  else
941  TArg = Template;
942  return TemplateArgumentLoc(
943  SemaRef.Context, TArg,
945  Arg.getLocation(), Arg.getEllipsisLoc());
946  }
947  }
948 
949  llvm_unreachable("Unhandled parsed template argument");
950 }
951 
952 /// Translates template arguments as provided by the parser
953 /// into template arguments used by semantic analysis.
955  TemplateArgumentListInfo &TemplateArgs) {
956  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
957  TemplateArgs.addArgument(translateTemplateArgument(*this,
958  TemplateArgsIn[I]));
959 }
960 
962  SourceLocation Loc,
963  IdentifierInfo *Name) {
964  NamedDecl *PrevDecl = SemaRef.LookupSingleName(
966  if (PrevDecl && PrevDecl->isTemplateParameter())
967  SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
968 }
969 
970 /// Convert a parsed type into a parsed template argument. This is mostly
971 /// trivial, except that we may have parsed a C++17 deduced class template
972 /// specialization type, in which case we should form a template template
973 /// argument instead of a type template argument.
975  TypeSourceInfo *TInfo;
976  QualType T = GetTypeFromParser(ParsedType.get(), &TInfo);
977  if (T.isNull())
978  return ParsedTemplateArgument();
979  assert(TInfo && "template argument with no location");
980 
981  // If we might have formed a deduced template specialization type, convert
982  // it to a template template argument.
983  if (getLangOpts().CPlusPlus17) {
984  TypeLoc TL = TInfo->getTypeLoc();
985  SourceLocation EllipsisLoc;
986  if (auto PET = TL.getAs<PackExpansionTypeLoc>()) {
987  EllipsisLoc = PET.getEllipsisLoc();
988  TL = PET.getPatternLoc();
989  }
990 
991  CXXScopeSpec SS;
992  if (auto ET = TL.getAs<ElaboratedTypeLoc>()) {
993  SS.Adopt(ET.getQualifierLoc());
994  TL = ET.getNamedTypeLoc();
995  }
996 
997  if (auto DTST = TL.getAs<DeducedTemplateSpecializationTypeLoc>()) {
998  TemplateName Name = DTST.getTypePtr()->getTemplateName();
999  if (SS.isSet())
1000  Name = Context.getQualifiedTemplateName(SS.getScopeRep(),
1001  /*HasTemplateKeyword*/ false,
1002  Name.getAsTemplateDecl());
1003  ParsedTemplateArgument Result(SS, TemplateTy::make(Name),
1004  DTST.getTemplateNameLoc());
1005  if (EllipsisLoc.isValid())
1006  Result = Result.getTemplatePackExpansion(EllipsisLoc);
1007  return Result;
1008  }
1009  }
1010 
1011  // This is a normal type template argument. Note, if the type template
1012  // argument is an injected-class-name for a template, it has a dual nature
1013  // and can be used as either a type or a template. We handle that in
1014  // convertTypeTemplateArgumentToTemplate.
1017  TInfo->getTypeLoc().getBeginLoc());
1018 }
1019 
1020 /// ActOnTypeParameter - Called when a C++ template type parameter
1021 /// (e.g., "typename T") has been parsed. Typename specifies whether
1022 /// the keyword "typename" was used to declare the type parameter
1023 /// (otherwise, "class" was used), and KeyLoc is the location of the
1024 /// "class" or "typename" keyword. ParamName is the name of the
1025 /// parameter (NULL indicates an unnamed template parameter) and
1026 /// ParamNameLoc is the location of the parameter name (if any).
1027 /// If the type parameter has a default argument, it will be added
1028 /// later via ActOnTypeParameterDefault.
1030  SourceLocation EllipsisLoc,
1031  SourceLocation KeyLoc,
1032  IdentifierInfo *ParamName,
1033  SourceLocation ParamNameLoc,
1034  unsigned Depth, unsigned Position,
1035  SourceLocation EqualLoc,
1036  ParsedType DefaultArg,
1037  bool HasTypeConstraint) {
1038  assert(S->isTemplateParamScope() &&
1039  "Template type parameter not in template parameter scope!");
1040 
1041  bool IsParameterPack = EllipsisLoc.isValid();
1042  TemplateTypeParmDecl *Param
1044  KeyLoc, ParamNameLoc, Depth, Position,
1045  ParamName, Typename, IsParameterPack,
1046  HasTypeConstraint);
1047  Param->setAccess(AS_public);
1048 
1049  if (Param->isParameterPack())
1050  if (auto *LSI = getEnclosingLambda())
1051  LSI->LocalPacks.push_back(Param);
1052 
1053  if (ParamName) {
1054  maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
1055 
1056  // Add the template parameter into the current scope.
1057  S->AddDecl(Param);
1058  IdResolver.AddDecl(Param);
1059  }
1060 
1061  // C++0x [temp.param]p9:
1062  // A default template-argument may be specified for any kind of
1063  // template-parameter that is not a template parameter pack.
1064  if (DefaultArg && IsParameterPack) {
1065  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1066  DefaultArg = nullptr;
1067  }
1068 
1069  // Handle the default argument, if provided.
1070  if (DefaultArg) {
1071  TypeSourceInfo *DefaultTInfo;
1072  GetTypeFromParser(DefaultArg, &DefaultTInfo);
1073 
1074  assert(DefaultTInfo && "expected source information for type");
1075 
1076  // Check for unexpanded parameter packs.
1077  if (DiagnoseUnexpandedParameterPack(ParamNameLoc, DefaultTInfo,
1078  UPPC_DefaultArgument))
1079  return Param;
1080 
1081  // Check the template argument itself.
1082  if (CheckTemplateArgument(Param, DefaultTInfo)) {
1083  Param->setInvalidDecl();
1084  return Param;
1085  }
1086 
1087  Param->setDefaultArgument(DefaultTInfo);
1088  }
1089 
1090  return Param;
1091 }
1092 
1093 /// Convert the parser's template argument list representation into our form.
1096  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
1097  TemplateId.RAngleLoc);
1098  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
1099  TemplateId.NumArgs);
1100  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
1101  return TemplateArgs;
1102 }
1103 
1105  TemplateIdAnnotation *TypeConstr,
1106  TemplateTypeParmDecl *ConstrainedParameter,
1107  SourceLocation EllipsisLoc) {
1108  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  // Cannot make a deduction guide when unparsed arguments are present.
2498  if (std::any_of(CD->param_begin(), CD->param_end(), [](ParmVarDecl *P) {
2499  return !P || P->hasUnparsedDefaultArg();
2500  }))
2501  continue;
2502 
2503  Transform.transformConstructor(FTD, CD);
2504  AddedAny = true;
2505  }
2506 
2507  // C++17 [over.match.class.deduct]
2508  // -- If C is not defined or does not declare any constructors, an
2509  // additional function template derived as above from a hypothetical
2510  // constructor C().
2511  if (!AddedAny)
2512  Transform.buildSimpleDeductionGuide(None);
2513 
2514  // -- An additional function template derived as above from a hypothetical
2515  // constructor C(C), called the copy deduction candidate.
2516  cast<CXXDeductionGuideDecl>(
2517  cast<FunctionTemplateDecl>(
2518  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2519  ->getTemplatedDecl())
2520  ->setIsCopyDeductionCandidate();
2521 }
2522 
2523 /// Diagnose the presence of a default template argument on a
2524 /// template parameter, which is ill-formed in certain contexts.
2525 ///
2526 /// \returns true if the default template argument should be dropped.
2529  SourceLocation ParamLoc,
2530  SourceRange DefArgRange) {
2531  switch (TPC) {
2533  case Sema::TPC_VarTemplate:
2535  return false;
2536 
2539  // C++ [temp.param]p9:
2540  // A default template-argument shall not be specified in a
2541  // function template declaration or a function template
2542  // definition [...]
2543  // If a friend function template declaration specifies a default
2544  // template-argument, that declaration shall be a definition and shall be
2545  // the only declaration of the function template in the translation unit.
2546  // (C++98/03 doesn't have this wording; see DR226).
2547  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2548  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2549  : diag::ext_template_parameter_default_in_function_template)
2550  << DefArgRange;
2551  return false;
2552 
2554  // C++0x [temp.param]p9:
2555  // A default template-argument shall not be specified in the
2556  // template-parameter-lists of the definition of a member of a
2557  // class template that appears outside of the member's class.
2558  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2559  << DefArgRange;
2560  return true;
2561 
2564  // C++ [temp.param]p9:
2565  // A default template-argument shall not be specified in a
2566  // friend template declaration.
2567  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2568  << DefArgRange;
2569  return true;
2570 
2571  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2572  // for friend function templates if there is only a single
2573  // declaration (and it is a definition). Strange!
2574  }
2575 
2576  llvm_unreachable("Invalid TemplateParamListContext!");
2577 }
2578 
2579 /// Check for unexpanded parameter packs within the template parameters
2580 /// of a template template parameter, recursively.
2582  TemplateTemplateParmDecl *TTP) {
2583  // A template template parameter which is a parameter pack is also a pack
2584  // expansion.
2585  if (TTP->isParameterPack())
2586  return false;
2587 
2589  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2590  NamedDecl *P = Params->getParam(I);
2591  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(P)) {
2592  if (!TTP->isParameterPack())
2593  if (const TypeConstraint *TC = TTP->getTypeConstraint())
2594  if (TC->hasExplicitTemplateArgs())
2595  for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
2596  if (S.DiagnoseUnexpandedParameterPack(ArgLoc,
2598  return true;
2599  continue;
2600  }
2601 
2602  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2603  if (!NTTP->isParameterPack() &&
2604  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2605  NTTP->getTypeSourceInfo(),
2607  return true;
2608 
2609  continue;
2610  }
2611 
2612  if (TemplateTemplateParmDecl *InnerTTP
2613  = dyn_cast<TemplateTemplateParmDecl>(P))
2614  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2615  return true;
2616  }
2617 
2618  return false;
2619 }
2620 
2621 /// Checks the validity of a template parameter list, possibly
2622 /// considering the template parameter list from a previous
2623 /// declaration.
2624 ///
2625 /// If an "old" template parameter list is provided, it must be
2626 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2627 /// template parameter list.
2628 ///
2629 /// \param NewParams Template parameter list for a new template
2630 /// declaration. This template parameter list will be updated with any
2631 /// default arguments that are carried through from the previous
2632 /// template parameter list.
2633 ///
2634 /// \param OldParams If provided, template parameter list from a
2635 /// previous declaration of the same template. Default template
2636 /// arguments will be merged from the old template parameter list to
2637 /// the new template parameter list.
2638 ///
2639 /// \param TPC Describes the context in which we are checking the given
2640 /// template parameter list.
2641 ///
2642 /// \param SkipBody If we might have already made a prior merged definition
2643 /// of this template visible, the corresponding body-skipping information.
2644 /// Default argument redefinition is not an error when skipping such a body,
2645 /// because (under the ODR) we can assume the default arguments are the same
2646 /// as the prior merged definition.
2647 ///
2648 /// \returns true if an error occurred, false otherwise.
2650  TemplateParameterList *OldParams,
2652  SkipBodyInfo *SkipBody) {
2653  bool Invalid = false;
2654 
2655  // C++ [temp.param]p10:
2656  // The set of default template-arguments available for use with a
2657  // template declaration or definition is obtained by merging the
2658  // default arguments from the definition (if in scope) and all
2659  // declarations in scope in the same way default function
2660  // arguments are (8.3.6).
2661  bool SawDefaultArgument = false;
2662  SourceLocation PreviousDefaultArgLoc;
2663 
2664  // Dummy initialization to avoid warnings.
2665  TemplateParameterList::iterator OldParam = NewParams->end();
2666  if (OldParams)
2667  OldParam = OldParams->begin();
2668 
2669  bool RemoveDefaultArguments = false;
2670  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2671  NewParamEnd = NewParams->end();
2672  NewParam != NewParamEnd; ++NewParam) {
2673  // Variables used to diagnose redundant default arguments
2674  bool RedundantDefaultArg = false;
2675  SourceLocation OldDefaultLoc;
2676  SourceLocation NewDefaultLoc;
2677 
2678  // Variable used to diagnose missing default arguments
2679  bool MissingDefaultArg = false;
2680 
2681  // Variable used to diagnose non-final parameter packs
2682  bool SawParameterPack = false;
2683 
2684  if (TemplateTypeParmDecl *NewTypeParm
2685  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2686  // Check the presence of a default argument here.
2687  if (NewTypeParm->hasDefaultArgument() &&
2689  NewTypeParm->getLocation(),
2690  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2691  .getSourceRange()))
2692  NewTypeParm->removeDefaultArgument();
2693 
2694  // Merge default arguments for template type parameters.
2695  TemplateTypeParmDecl *OldTypeParm
2696  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2697  if (NewTypeParm->isParameterPack()) {
2698  assert(!NewTypeParm->hasDefaultArgument() &&
2699  "Parameter packs can't have a default argument!");
2700  SawParameterPack = true;
2701  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2702  NewTypeParm->hasDefaultArgument() &&
2703  (!SkipBody || !SkipBody->ShouldSkip)) {
2704  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2705  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2706  SawDefaultArgument = true;
2707  RedundantDefaultArg = true;
2708  PreviousDefaultArgLoc = NewDefaultLoc;
2709  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2710  // Merge the default argument from the old declaration to the
2711  // new declaration.
2712  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2713  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2714  } else if (NewTypeParm->hasDefaultArgument()) {
2715  SawDefaultArgument = true;
2716  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2717  } else if (SawDefaultArgument)
2718  MissingDefaultArg = true;
2719  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2720  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2721  // Check for unexpanded parameter packs.
2722  if (!NewNonTypeParm->isParameterPack() &&
2723  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2724  NewNonTypeParm->getTypeSourceInfo(),
2725  UPPC_NonTypeTemplateParameterType)) {
2726  Invalid = true;
2727  continue;
2728  }
2729 
2730  // Check the presence of a default argument here.
2731  if (NewNonTypeParm->hasDefaultArgument() &&
2733  NewNonTypeParm->getLocation(),
2734  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2735  NewNonTypeParm->removeDefaultArgument();
2736  }
2737 
2738  // Merge default arguments for non-type template parameters
2739  NonTypeTemplateParmDecl *OldNonTypeParm
2740  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2741  if (NewNonTypeParm->isParameterPack()) {
2742  assert(!NewNonTypeParm->hasDefaultArgument() &&
2743  "Parameter packs can't have a default argument!");
2744  if (!NewNonTypeParm->isPackExpansion())
2745  SawParameterPack = true;
2746  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2747  NewNonTypeParm->hasDefaultArgument() &&
2748  (!SkipBody || !SkipBody->ShouldSkip)) {
2749  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2750  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2751  SawDefaultArgument = true;
2752  RedundantDefaultArg = true;
2753  PreviousDefaultArgLoc = NewDefaultLoc;
2754  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2755  // Merge the default argument from the old declaration to the
2756  // new declaration.
2757  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2758  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2759  } else if (NewNonTypeParm->hasDefaultArgument()) {
2760  SawDefaultArgument = true;
2761  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2762  } else if (SawDefaultArgument)
2763  MissingDefaultArg = true;
2764  } else {
2765  TemplateTemplateParmDecl *NewTemplateParm
2766  = cast<TemplateTemplateParmDecl>(*NewParam);
2767 
2768  // Check for unexpanded parameter packs, recursively.
2769  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2770  Invalid = true;
2771  continue;
2772  }
2773 
2774  // Check the presence of a default argument here.
2775  if (NewTemplateParm->hasDefaultArgument() &&
2777  NewTemplateParm->getLocation(),
2778  NewTemplateParm->getDefaultArgument().getSourceRange()))
2779  NewTemplateParm->removeDefaultArgument();
2780 
2781  // Merge default arguments for template template parameters
2782  TemplateTemplateParmDecl *OldTemplateParm
2783  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2784  if (NewTemplateParm->isParameterPack()) {
2785  assert(!NewTemplateParm->hasDefaultArgument() &&
2786  "Parameter packs can't have a default argument!");
2787  if (!NewTemplateParm->isPackExpansion())
2788  SawParameterPack = true;
2789  } else if (OldTemplateParm &&
2790  hasVisibleDefaultArgument(OldTemplateParm) &&
2791  NewTemplateParm->hasDefaultArgument() &&
2792  (!SkipBody || !SkipBody->ShouldSkip)) {
2793  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2794  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2795  SawDefaultArgument = true;
2796  RedundantDefaultArg = true;
2797  PreviousDefaultArgLoc = NewDefaultLoc;
2798  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2799  // Merge the default argument from the old declaration to the
2800  // new declaration.
2801  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2802  PreviousDefaultArgLoc
2803  = OldTemplateParm->getDefaultArgument().getLocation();
2804  } else if (NewTemplateParm->hasDefaultArgument()) {
2805  SawDefaultArgument = true;
2806  PreviousDefaultArgLoc
2807  = NewTemplateParm->getDefaultArgument().getLocation();
2808  } else if (SawDefaultArgument)
2809  MissingDefaultArg = true;
2810  }
2811 
2812  // C++11 [temp.param]p11:
2813  // If a template parameter of a primary class template or alias template
2814  // is a template parameter pack, it shall be the last template parameter.
2815  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2816  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2817  TPC == TPC_TypeAliasTemplate)) {
2818  Diag((*NewParam)->getLocation(),
2819  diag::err_template_param_pack_must_be_last_template_parameter);
2820  Invalid = true;
2821  }
2822 
2823  if (RedundantDefaultArg) {
2824  // C++ [temp.param]p12:
2825  // A template-parameter shall not be given default arguments
2826  // by two different declarations in the same scope.
2827  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2828  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2829  Invalid = true;
2830  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2831  // C++ [temp.param]p11:
2832  // If a template-parameter of a class template has a default
2833  // template-argument, each subsequent template-parameter shall either
2834  // have a default template-argument supplied or be a template parameter
2835  // pack.
2836  Diag((*NewParam)->getLocation(),
2837  diag::err_template_param_default_arg_missing);
2838  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2839  Invalid = true;
2840  RemoveDefaultArguments = true;
2841  }
2842 
2843  // If we have an old template parameter list that we're merging
2844  // in, move on to the next parameter.
2845  if (OldParams)
2846  ++OldParam;
2847  }
2848 
2849  // We were missing some default arguments at the end of the list, so remove
2850  // all of the default arguments.
2851  if (RemoveDefaultArguments) {
2852  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2853  NewParamEnd = NewParams->end();
2854  NewParam != NewParamEnd; ++NewParam) {
2855  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2856  TTP->removeDefaultArgument();
2857  else if (NonTypeTemplateParmDecl *NTTP
2858  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2859  NTTP->removeDefaultArgument();
2860  else
2861  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2862  }
2863  }
2864 
2865  return Invalid;
2866 }
2867 
2868 namespace {
2869 
2870 /// A class which looks for a use of a certain level of template
2871 /// parameter.
2872 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2874 
2875  unsigned Depth;
2876 
2877  // Whether we're looking for a use of a template parameter that makes the
2878  // overall construct type-dependent / a dependent type. This is strictly
2879  // best-effort for now; we may fail to match at all for a dependent type
2880  // in some cases if this is set.
2881  bool IgnoreNonTypeDependent;
2882 
2883  bool Match;
2884  SourceLocation MatchLoc;
2885 
2886  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2887  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2888  Match(false) {}
2889 
2890  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2891  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2892  NamedDecl *ND = Params->getParam(0);
2893  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2894  Depth = PD->getDepth();
2895  } else if (NonTypeTemplateParmDecl *PD =
2896  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2897  Depth = PD->getDepth();
2898  } else {
2899  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2900  }
2901  }
2902 
2903  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2904  if (ParmDepth >= Depth) {
2905  Match = true;
2906  MatchLoc = Loc;
2907  return true;
2908  }
2909  return false;
2910  }
2911 
2912  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2913  // Prune out non-type-dependent expressions if requested. This can
2914  // sometimes result in us failing to find a template parameter reference
2915  // (if a value-dependent expression creates a dependent type), but this
2916  // mode is best-effort only.
2917  if (auto *E = dyn_cast_or_null<Expr>(S))
2918  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2919  return true;
2920  return super::TraverseStmt(S, Q);
2921  }
2922 
2923  bool TraverseTypeLoc(TypeLoc TL) {
2924  if (IgnoreNonTypeDependent && !TL.isNull() &&
2925  !TL.getType()->isDependentType())
2926  return true;
2927  return super::TraverseTypeLoc(TL);
2928  }
2929 
2930  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2931  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2932  }
2933 
2934  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2935  // For a best-effort search, keep looking until we find a location.
2936  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2937  }
2938 
2939  bool TraverseTemplateName(TemplateName N) {
2940  if (TemplateTemplateParmDecl *PD =
2941  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2942  if (Matches(PD->getDepth()))
2943  return false;
2944  return super::TraverseTemplateName(N);
2945  }
2946 
2947  bool VisitDeclRefExpr(DeclRefExpr *E) {
2948  if (NonTypeTemplateParmDecl *PD =
2949  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2950  if (Matches(PD->getDepth(), E->getExprLoc()))
2951  return false;
2952  return super::VisitDeclRefExpr(E);
2953  }
2954 
2955  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2956  return TraverseType(T->getReplacementType());
2957  }
2958 
2959  bool
2960  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2961  return TraverseTemplateArgument(T->getArgumentPack());
2962  }
2963 
2964  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2965  return TraverseType(T->getInjectedSpecializationType());
2966  }
2967 };
2968 } // end anonymous namespace
2969 
2970 /// Determines whether a given type depends on the given parameter
2971 /// list.
2972 static bool
2974  if (!Params->size())
2975  return false;
2976 
2977  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2978  Checker.TraverseType(T);
2979  return Checker.Match;
2980 }
2981 
2982 // Find the source range corresponding to the named type in the given
2983 // nested-name-specifier, if any.
2985  QualType T,
2986  const CXXScopeSpec &SS) {
2988  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2989  if (const Type *CurType = NNS->getAsType()) {
2990  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2991  return NNSLoc.getTypeLoc().getSourceRange();
2992  } else
2993  break;
2994 
2995  NNSLoc = NNSLoc.getPrefix();
2996  }
2997 
2998  return SourceRange();
2999 }
3000 
3001 /// Match the given template parameter lists to the given scope
3002 /// specifier, returning the template parameter list that applies to the
3003 /// name.
3004 ///
3005 /// \param DeclStartLoc the start of the declaration that has a scope
3006 /// specifier or a template parameter list.
3007 ///
3008 /// \param DeclLoc The location of the declaration itself.
3009 ///
3010 /// \param SS the scope specifier that will be matched to the given template
3011 /// parameter lists. This scope specifier precedes a qualified name that is
3012 /// being declared.
3013 ///
3014 /// \param TemplateId The template-id following the scope specifier, if there
3015 /// is one. Used to check for a missing 'template<>'.
3016 ///
3017 /// \param ParamLists the template parameter lists, from the outermost to the
3018 /// innermost template parameter lists.
3019 ///
3020 /// \param IsFriend Whether to apply the slightly different rules for
3021 /// matching template parameters to scope specifiers in friend
3022 /// declarations.
3023 ///
3024 /// \param IsMemberSpecialization will be set true if the scope specifier
3025 /// denotes a fully-specialized type, and therefore this is a declaration of
3026 /// a member specialization.
3027 ///
3028 /// \returns the template parameter list, if any, that corresponds to the
3029 /// name that is preceded by the scope specifier @p SS. This template
3030 /// parameter list may have template parameters (if we're declaring a
3031 /// template) or may have no template parameters (if we're declaring a
3032 /// template specialization), or may be NULL (if what we're declaring isn't
3033 /// itself a template).
3035  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
3036  TemplateIdAnnotation *TemplateId,
3037  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
3038  bool &IsMemberSpecialization, bool &Invalid, bool SuppressDiagnostic) {
3039  IsMemberSpecialization = false;
3040  Invalid = false;
3041 
3042  // The sequence of nested types to which we will match up the template
3043  // parameter lists. We first build this list by starting with the type named
3044  // by the nested-name-specifier and walking out until we run out of types.
3045  SmallVector<QualType, 4> NestedTypes;
3046  QualType T;
3047  if (SS.getScopeRep()) {
3048  if (CXXRecordDecl *Record
3049  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
3050  T = Context.getTypeDeclType(Record);
3051  else
3052  T = QualType(SS.getScopeRep()->getAsType(), 0);
3053  }
3054 
3055  // If we found an explicit specialization that prevents us from needing
3056  // 'template<>' headers, this will be set to the location of that
3057  // explicit specialization.
3058  SourceLocation ExplicitSpecLoc;
3059 
3060  while (!T.isNull()) {
3061  NestedTypes.push_back(T);
3062 
3063  // Retrieve the parent of a record type.
3064  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3065  // If this type is an explicit specialization, we're done.
3067  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3068  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
3069  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
3070  ExplicitSpecLoc = Spec->getLocation();
3071  break;
3072  }
3073  } else if (Record->getTemplateSpecializationKind()
3075  ExplicitSpecLoc = Record->getLocation();
3076  break;
3077  }
3078 
3079  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
3080  T = Context.getTypeDeclType(Parent);
3081  else
3082  T = QualType();
3083  continue;
3084  }
3085 
3086  if (const TemplateSpecializationType *TST
3088  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3089  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
3090  T = Context.getTypeDeclType(Parent);
3091  else
3092  T = QualType();
3093  continue;
3094  }
3095  }
3096 
3097  // Look one step prior in a dependent template specialization type.
3098  if (const DependentTemplateSpecializationType *DependentTST
3100  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
3101  T = QualType(NNS->getAsType(), 0);
3102  else
3103  T = QualType();
3104  continue;
3105  }
3106 
3107  // Look one step prior in a dependent name type.
3108  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
3109  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
3110  T = QualType(NNS->getAsType(), 0);
3111  else
3112  T = QualType();
3113  continue;
3114  }
3115 
3116  // Retrieve the parent of an enumeration type.
3117  if (const EnumType *EnumT = T->getAs<EnumType>()) {
3118  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
3119  // check here.
3120  EnumDecl *Enum = EnumT->getDecl();
3121 
3122  // Get to the parent type.
3123  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
3124  T = Context.getTypeDeclType(Parent);
3125  else
3126  T = QualType();
3127  continue;
3128  }
3129 
3130  T = QualType();
3131  }
3132  // Reverse the nested types list, since we want to traverse from the outermost
3133  // to the innermost while checking template-parameter-lists.
3134  std::reverse(NestedTypes.begin(), NestedTypes.end());
3135 
3136  // C++0x [temp.expl.spec]p17:
3137  // A member or a member template may be nested within many
3138  // enclosing class templates. In an explicit specialization for
3139  // such a member, the member declaration shall be preceded by a
3140  // template<> for each enclosing class template that is
3141  // explicitly specialized.
3142  bool SawNonEmptyTemplateParameterList = false;
3143 
3144  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
3145  if (SawNonEmptyTemplateParameterList) {
3146  if (!SuppressDiagnostic)
3147  Diag(DeclLoc, diag::err_specialize_member_of_template)
3148  << !Recovery << Range;
3149  Invalid = true;
3150  IsMemberSpecialization = false;
3151  return true;
3152  }
3153 
3154  return false;
3155  };
3156 
3157  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
3158  // Check that we can have an explicit specialization here.
3159  if (CheckExplicitSpecialization(Range, true))
3160  return true;
3161 
3162  // We don't have a template header, but we should.
3163  SourceLocation ExpectedTemplateLoc;
3164  if (!ParamLists.empty())
3165  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
3166  else
3167  ExpectedTemplateLoc = DeclStartLoc;
3168 
3169  if (!SuppressDiagnostic)
3170  Diag(DeclLoc, diag::err_template_spec_needs_header)
3171  << Range
3172  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
3173  return false;
3174  };
3175 
3176  unsigned ParamIdx = 0;
3177  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
3178  ++TypeIdx) {
3179  T = NestedTypes[TypeIdx];
3180 
3181  // Whether we expect a 'template<>' header.
3182  bool NeedEmptyTemplateHeader = false;
3183 
3184  // Whether we expect a template header with parameters.
3185  bool NeedNonemptyTemplateHeader = false;
3186 
3187  // For a dependent type, the set of template parameters that we
3188  // expect to see.
3189  TemplateParameterList *ExpectedTemplateParams = nullptr;
3190 
3191  // C++0x [temp.expl.spec]p15:
3192  // A member or a member template may be nested within many enclosing
3193  // class templates. In an explicit specialization for such a member, the
3194  // member declaration shall be preceded by a template<> for each
3195  // enclosing class template that is explicitly specialized.
3196  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3198  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
3199  ExpectedTemplateParams = Partial->getTemplateParameters();
3200  NeedNonemptyTemplateHeader = true;
3201  } else if (Record->isDependentType()) {
3202  if (Record->getDescribedClassTemplate()) {
3203  ExpectedTemplateParams = Record->getDescribedClassTemplate()
3204  ->getTemplateParameters();
3205  NeedNonemptyTemplateHeader = true;
3206  }
3207  } else if (ClassTemplateSpecializationDecl *Spec
3208  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3209  // C++0x [temp.expl.spec]p4:
3210  // Members of an explicitly specialized class template are defined
3211  // in the same manner as members of normal classes, and not using
3212  // the template<> syntax.
3213  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
3214  NeedEmptyTemplateHeader = true;
3215  else
3216  continue;
3217  } else if (Record->getTemplateSpecializationKind()) {
3218  if (Record->getTemplateSpecializationKind()
3220  TypeIdx == NumTypes - 1)
3221  IsMemberSpecialization = true;
3222 
3223  continue;
3224  }
3225  } else if (const TemplateSpecializationType *TST
3227  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3228  ExpectedTemplateParams = Template->getTemplateParameters();
3229  NeedNonemptyTemplateHeader = true;
3230  }
3231  } else if (T->getAs<DependentTemplateSpecializationType>()) {
3232  // FIXME: We actually could/should check the template arguments here
3233  // against the corresponding template parameter list.
3234  NeedNonemptyTemplateHeader = false;
3235  }
3236 
3237  // C++ [temp.expl.spec]p16:
3238  // In an explicit specialization declaration for a member of a class
3239  // template or a member template that ap- pears in namespace scope, the
3240  // member template and some of its enclosing class templates may remain
3241  // unspecialized, except that the declaration shall not explicitly
3242  // specialize a class member template if its en- closing class templates
3243  // are not explicitly specialized as well.
3244  if (ParamIdx < ParamLists.size()) {
3245  if (ParamLists[ParamIdx]->size() == 0) {
3246  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3247  false))
3248  return nullptr;
3249  } else
3250  SawNonEmptyTemplateParameterList = true;
3251  }
3252 
3253  if (NeedEmptyTemplateHeader) {
3254  // If we're on the last of the types, and we need a 'template<>' header
3255  // here, then it's a member specialization.
3256  if (TypeIdx == NumTypes - 1)
3257  IsMemberSpecialization = true;
3258 
3259  if (ParamIdx < ParamLists.size()) {
3260  if (ParamLists[ParamIdx]->size() > 0) {
3261  // The header has template parameters when it shouldn't. Complain.
3262  if (!SuppressDiagnostic)
3263  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3264  diag::err_template_param_list_matches_nontemplate)
3265  << T
3266  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
3267  ParamLists[ParamIdx]->getRAngleLoc())
3268  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3269  Invalid = true;
3270  return nullptr;
3271  }
3272 
3273  // Consume this template header.
3274  ++ParamIdx;
3275  continue;
3276  }
3277 
3278  if (!IsFriend)
3279  if (DiagnoseMissingExplicitSpecialization(
3280  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
3281  return nullptr;
3282 
3283  continue;
3284  }
3285 
3286  if (NeedNonemptyTemplateHeader) {
3287  // In friend declarations we can have template-ids which don't
3288  // depend on the corresponding template parameter lists. But
3289  // assume that empty parameter lists are supposed to match this
3290  // template-id.
3291  if (IsFriend && T->isDependentType()) {
3292  if (ParamIdx < ParamLists.size() &&
3293  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
3294  ExpectedTemplateParams = nullptr;
3295  else
3296  continue;
3297  }
3298 
3299  if (ParamIdx < ParamLists.size()) {
3300  // Check the template parameter list, if we can.
3301  if (ExpectedTemplateParams &&
3302  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
3303  ExpectedTemplateParams,
3304  !SuppressDiagnostic, TPL_TemplateMatch))
3305  Invalid = true;
3306 
3307  if (!Invalid &&
3308  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
3309  TPC_ClassTemplateMember))
3310  Invalid = true;
3311 
3312  ++ParamIdx;
3313  continue;
3314  }
3315 
3316  if (!SuppressDiagnostic)
3317  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
3318  << T
3319  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3320  Invalid = true;
3321  continue;
3322  }
3323  }
3324 
3325  // If there were at least as many template-ids as there were template
3326  // parameter lists, then there are no template parameter lists remaining for
3327  // the declaration itself.
3328  if (ParamIdx >= ParamLists.size()) {
3329  if (TemplateId && !IsFriend) {
3330  // We don't have a template header for the declaration itself, but we
3331  // should.
3332  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
3333  TemplateId->RAngleLoc));
3334 
3335  // Fabricate an empty template parameter list for the invented header.
3337  SourceLocation(), None,
3338  SourceLocation(), nullptr);
3339  }
3340 
3341  return nullptr;
3342  }
3343 
3344  // If there were too many template parameter lists, complain about that now.
3345  if (ParamIdx < ParamLists.size() - 1) {
3346  bool HasAnyExplicitSpecHeader = false;
3347  bool AllExplicitSpecHeaders = true;
3348  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
3349  if (ParamLists[I]->size() == 0)
3350  HasAnyExplicitSpecHeader = true;
3351  else
3352  AllExplicitSpecHeaders = false;
3353  }
3354 
3355  if (!SuppressDiagnostic)
3356  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3357  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
3358  : diag::err_template_spec_extra_headers)
3359  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
3360  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
3361 
3362  // If there was a specialization somewhere, such that 'template<>' is
3363  // not required, and there were any 'template<>' headers, note where the
3364  // specialization occurred.
3365  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader &&
3366  !SuppressDiagnostic)
3367  Diag(ExplicitSpecLoc,
3368  diag::note_explicit_template_spec_does_not_need_header)
3369  << NestedTypes.back();
3370 
3371  // We have a template parameter list with no corresponding scope, which
3372  // means that the resulting template declaration can't be instantiated
3373  // properly (we'll end up with dependent nodes when we shouldn't).
3374  if (!AllExplicitSpecHeaders)
3375  Invalid = true;
3376  }
3377 
3378  // C++ [temp.expl.spec]p16:
3379  // In an explicit specialization declaration for a member of a class
3380  // template or a member template that ap- pears in namespace scope, the
3381  // member template and some of its enclosing class templates may remain
3382  // unspecialized, except that the declaration shall not explicitly
3383  // specialize a class member template if its en- closing class templates
3384  // are not explicitly specialized as well.
3385  if (ParamLists.back()->size() == 0 &&
3386  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3387  false))
3388  return nullptr;
3389 
3390  // Return the last template parameter list, which corresponds to the
3391  // entity being declared.
3392  return ParamLists.back();
3393 }
3394 
3396  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
3397  Diag(Template->getLocation(), diag::note_template_declared_here)
3398  << (isa<FunctionTemplateDecl>(Template)
3399  ? 0
3400  : isa<ClassTemplateDecl>(Template)
3401  ? 1
3402  : isa<VarTemplateDecl>(Template)
3403  ? 2
3404  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
3405  << Template->getDeclName();
3406  return;
3407  }
3408 
3409  if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
3410  for (OverloadedTemplateStorage::iterator I = OST->begin(),
3411  IEnd = OST->end();
3412  I != IEnd; ++I)
3413  Diag((*I)->getLocation(), diag::note_template_declared_here)
3414  << 0 << (*I)->getDeclName();
3415 
3416  return;
3417  }
3418 }
3419 
3420 static QualType
3422  const SmallVectorImpl<TemplateArgument> &Converted,
3423  SourceLocation TemplateLoc,
3424  TemplateArgumentListInfo &TemplateArgs) {
3425  ASTContext &Context = SemaRef.getASTContext();
3426  switch (BTD->getBuiltinTemplateKind()) {
3427  case BTK__make_integer_seq: {
3428  // Specializations of __make_integer_seq<S, T, N> are treated like
3429  // S<T, 0, ..., N-1>.
3430 
3431  // C++14 [inteseq.intseq]p1:
3432  // T shall be an integer type.
3433  if (!Converted[1].getAsType()->isIntegralType(Context)) {
3434  SemaRef.Diag(TemplateArgs[1].getLocation(),
3435  diag::err_integer_sequence_integral_element_type);
3436  return QualType();
3437  }
3438 
3439  // C++14 [inteseq.make]p1:
3440  // If N is negative the program is ill-formed.
3441  TemplateArgument NumArgsArg = Converted[2];
3442  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
3443  if (NumArgs < 0) {
3444  SemaRef.Diag(TemplateArgs[2].getLocation(),
3445  diag::err_integer_sequence_negative_length);
3446  return QualType();
3447  }
3448 
3449  QualType ArgTy = NumArgsArg.getIntegralType();
3450  TemplateArgumentListInfo SyntheticTemplateArgs;
3451  // The type argument gets reused as the first template argument in the
3452  // synthetic template argument list.
3453  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
3454  // Expand N into 0 ... N-1.
3455  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
3456  I < NumArgs; ++I) {
3457  TemplateArgument TA(Context, I, ArgTy);
3458  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
3459  TA, ArgTy, TemplateArgs[2].getLocation()));
3460  }
3461  // The first template argument will be reused as the template decl that
3462  // our synthetic template arguments will be applied to.
3463  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
3464  TemplateLoc, SyntheticTemplateArgs);
3465  }
3466 
3468  // Specializations of
3469  // __type_pack_element<Index, T_1, ..., T_N>
3470  // are treated like T_Index.
3471  assert(Converted.size() == 2 &&
3472  "__type_pack_element should be given an index and a parameter pack");
3473 
3474  // If the Index is out of bounds, the program is ill-formed.
3475  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
3476  llvm::APSInt Index = IndexArg.getAsIntegral();
3477  assert(Index >= 0 && "the index used with __type_pack_element should be of "
3478  "type std::size_t, and hence be non-negative");
3479  if (Index >= Ts.pack_size()) {
3480  SemaRef.Diag(TemplateArgs[0].getLocation(),
3481  diag::err_type_pack_element_out_of_bounds);
3482  return QualType();
3483  }
3484 
3485  // We simply return the type at index `Index`.
3486  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
3487  return Nth->getAsType();
3488  }
3489  llvm_unreachable("unexpected BuiltinTemplateDecl!");
3490 }
3491 
3492 /// Determine whether this alias template is "enable_if_t".
3493 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3494  return AliasTemplate->getName().equals("enable_if_t");
3495 }
3496 
3497 /// Collect all of the separable terms in the given condition, which
3498 /// might be a conjunction.
3499 ///
3500 /// FIXME: The right answer is to convert the logical expression into
3501 /// disjunctive normal form, so we can find the first failed term
3502 /// within each possible clause.
3503 static void collectConjunctionTerms(Expr *Clause,
3504  SmallVectorImpl<Expr *> &Terms) {
3505  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3506  if (BinOp->getOpcode() == BO_LAnd) {
3507  collectConjunctionTerms(BinOp->getLHS(), Terms);
3508  collectConjunctionTerms(BinOp->getRHS(), Terms);
3509  }
3510 
3511  return;
3512  }
3513 
3514  Terms.push_back(Clause);
3515 }
3516 
3517 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3518 // a left-hand side that is value-dependent but never true. Identify
3519 // the idiom and ignore that term.
3521  // Top-level '||'.
3522  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3523  if (!BinOp) return Cond;
3524 
3525  if (BinOp->getOpcode() != BO_LOr) return Cond;
3526 
3527  // With an inner '==' that has a literal on the right-hand side.
3528  Expr *LHS = BinOp->getLHS();
3529  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3530  if (!InnerBinOp) return Cond;
3531 
3532  if (InnerBinOp->getOpcode() != BO_EQ ||
3533  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3534  return Cond;
3535 
3536  // If the inner binary operation came from a macro expansion named
3537  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3538  // of the '||', which is the real, user-provided condition.
3539  SourceLocation Loc = InnerBinOp->getExprLoc();
3540  if (!Loc.isMacroID()) return Cond;
3541 
3542  StringRef MacroName = PP.getImmediateMacroName(Loc);
3543  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3544  return BinOp->getRHS();
3545 
3546  return Cond;
3547 }
3548 
3549 namespace {
3550 
3551 // A PrinterHelper that prints more helpful diagnostics for some sub-expressions
3552 // within failing boolean expression, such as substituting template parameters
3553 // for actual types.
3554 class FailedBooleanConditionPrinterHelper : public PrinterHelper {
3555 public:
3556  explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
3557  : Policy(P) {}
3558 
3559  bool handledStmt(Stmt *E, raw_ostream &OS) override {
3560  const auto *DR = dyn_cast<DeclRefExpr>(E);
3561  if (DR && DR->getQualifier()) {
3562  // If this is a qualified name, expand the template arguments in nested
3563  // qualifiers.
3564  DR->getQualifier()->print(OS, Policy, true);
3565  // Then print the decl itself.
3566  const ValueDecl *VD = DR->getDecl();
3567  OS << VD->getName();
3568  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3569  // This is a template variable, print the expanded template arguments.
3570  printTemplateArgumentList(OS, IV->getTemplateArgs().asArray(), Policy);
3571  }
3572  return true;
3573  }
3574  return false;
3575  }
3576 
3577 private:
3578  const PrintingPolicy Policy;
3579 };
3580 
3581 } // end anonymous namespace
3582 
3583 std::pair<Expr *, std::string>
3585  Cond = lookThroughRangesV3Condition(PP, Cond);
3586 
3587  // Separate out all of the terms in a conjunction.
3588  SmallVector<Expr *, 4> Terms;
3589  collectConjunctionTerms(Cond, Terms);
3590 
3591  // Determine which term failed.
3592  Expr *FailedCond = nullptr;
3593  for (Expr *Term : Terms) {
3594  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3595 
3596  // Literals are uninteresting.
3597  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3598  isa<IntegerLiteral>(TermAsWritten))
3599  continue;
3600 
3601  // The initialization of the parameter from the argument is
3602  // a constant-evaluated context.
3603  EnterExpressionEvaluationContext ConstantEvaluated(
3605 
3606  bool Succeeded;
3607  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3608  !Succeeded) {
3609  FailedCond = TermAsWritten;
3610  break;
3611  }
3612  }
3613  if (!FailedCond)
3614  FailedCond = Cond->IgnoreParenImpCasts();
3615 
3616  std::string Description;
3617  {
3618  llvm::raw_string_ostream Out(Description);
3619  PrintingPolicy Policy = getPrintingPolicy();
3620  Policy.PrintCanonicalTypes = true;
3621  FailedBooleanConditionPrinterHelper Helper(Policy);
3622  FailedCond->printPretty(Out, &Helper, Policy, 0, "\n", nullptr);
3623  }
3624  return { FailedCond, Description };
3625 }
3626 
3628  SourceLocation TemplateLoc,
3629  TemplateArgumentListInfo &TemplateArgs) {
3631  = Name.getUnderlying().getAsDependentTemplateName();
3632  if (DTN && DTN->isIdentifier())
3633  // When building a template-id where the template-name is dependent,
3634  // assume the template is a type template. Either our assumption is
3635  // correct, or the code is ill-formed and will be diagnosed when the
3636  // dependent name is substituted.
3638  DTN->getQualifier(),
3639  DTN->getIdentifier(),
3640  TemplateArgs);
3641 
3642  if (Name.getAsAssumedTemplateName() &&
3643  resolveAssumedTemplateNameAsType(/*Scope*/nullptr, Name, TemplateLoc))
3644  return QualType();
3645 
3646  TemplateDecl *Template = Name.getAsTemplateDecl();
3647  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3648  isa<VarTemplateDecl>(Template) || isa<ConceptDecl>(Template)) {
3649  // We might have a substituted template template parameter pack. If so,
3650  // build a template specialization type for it.
3651  if (Name.getAsSubstTemplateTemplateParmPack())
3652  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3653 
3654  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3655  << Name;
3656  NoteAllFoundTemplates(Name);
3657  return QualType();
3658  }
3659 
3660  // Check that the template argument list is well-formed for this
3661  // template.
3663  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3664  false, Converted,
3665  /*UpdateArgsWithConversion=*/true))
3666  return QualType();
3667 
3668  QualType CanonType;
3669 
3671  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3672 
3673  // Find the canonical type for this type alias template specialization.
3674  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3675  if (Pattern->isInvalidDecl())
3676  return QualType();
3677 
3679  Converted);
3680 
3681  // Only substitute for the innermost template argument list.
3682  MultiLevelTemplateArgumentList TemplateArgLists;
3683  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3684  TemplateArgLists.addOuterRetainedLevels(
3685  AliasTemplate->getTemplateParameters()->getDepth());
3686 
3688  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3689  if (Inst.isInvalid())
3690  return QualType();
3691 
3692  CanonType = SubstType(Pattern->getUnderlyingType(),
3693  TemplateArgLists, AliasTemplate->getLocation(),
3694  AliasTemplate->getDeclName());
3695  if (CanonType.isNull()) {
3696  // If this was enable_if and we failed to find the nested type
3697  // within enable_if in a SFINAE context, dig out the specific
3698  // enable_if condition that failed and present that instead.
3700  if (auto DeductionInfo = isSFINAEContext()) {
3701  if (*DeductionInfo &&
3702  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3703  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3704  diag::err_typename_nested_not_found_enable_if &&
3705  TemplateArgs[0].getArgument().getKind()
3707  Expr *FailedCond;
3708  std::string FailedDescription;
3709  std::tie(FailedCond, FailedDescription) =
3710  findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
3711 
3712  // Remove the old SFINAE diagnostic.
3713  PartialDiagnosticAt OldDiag =
3715  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3716 
3717  // Add a new SFINAE diagnostic specifying which condition
3718  // failed.
3719  (*DeductionInfo)->addSFINAEDiagnostic(
3720  OldDiag.first,
3721  PDiag(diag::err_typename_nested_not_found_requirement)
3722  << FailedDescription
3723  << FailedCond->getSourceRange());
3724  }
3725  }
3726  }
3727 
3728  return QualType();
3729  }
3730  } else if (Name.isDependent() ||
3732  TemplateArgs, Converted)) {
3733  // This class template specialization is a dependent
3734  // type. Therefore, its canonical type is another class template
3735  // specialization type that contains all of the converted
3736  // arguments in canonical form. This ensures that, e.g., A<T> and
3737  // A<T, T> have identical types when A is declared as:
3738  //
3739  // template<typename T, typename U = T> struct A;
3740  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3741 
3742  // This might work out to be a current instantiation, in which
3743  // case the canonical type needs to be the InjectedClassNameType.
3744  //
3745  // TODO: in theory this could be a simple hashtable lookup; most
3746  // changes to CurContext don't change the set of current
3747  // instantiations.
3748  if (isa<ClassTemplateDecl>(Template)) {
3749  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3750  // If we get out to a namespace, we're done.
3751  if (Ctx->isFileContext()) break;
3752 
3753  // If this isn't a record, keep looking.
3754  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3755  if (!Record) continue;
3756 
3757  // Look for one of the two cases with InjectedClassNameTypes
3758  // and check whether it's the same template.
3759  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3760  !Record->getDescribedClassTemplate())
3761  continue;
3762 
3763  // Fetch the injected class name type and check whether its
3764  // injected type is equal to the type we just built.
3765  QualType ICNT = Context.getTypeDeclType(Record);
3766  QualType Injected = cast<InjectedClassNameType>(ICNT)
3767  ->getInjectedSpecializationType();
3768 
3769  if (CanonType != Injected->getCanonicalTypeInternal())
3770  continue;
3771 
3772  // If so, the canonical type of this TST is the injected
3773  // class name type of the record we just found.
3774  assert(ICNT.isCanonical());
3775  CanonType = ICNT;
3776  break;
3777  }
3778  }
3779  } else if (ClassTemplateDecl *ClassTemplate
3780  = dyn_cast<ClassTemplateDecl>(Template)) {
3781  // Find the class template specialization declaration that
3782  // corresponds to these arguments.
3783  void *InsertPos = nullptr;
3785  = ClassTemplate->findSpecialization(Converted, InsertPos);
3786  if (!Decl) {
3787  // This is the first time we have referenced this class template
3788  // specialization. Create the canonical declaration and add it to
3789  // the set of specializations.
3791  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3792  ClassTemplate->getDeclContext(),
3793  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3794  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3795  ClassTemplate->AddSpecialization(Decl, InsertPos);
3796  if (ClassTemplate->isOutOfLine())
3797  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3798  }
3799 
3800  if (Decl->getSpecializationKind() == TSK_Undeclared &&
3801  ClassTemplate->getTemplatedDecl()->hasAttrs()) {
3802  InstantiatingTemplate Inst(*this, TemplateLoc, Decl);
3803  if (!Inst.isInvalid()) {
3804  MultiLevelTemplateArgumentList TemplateArgLists;
3805  TemplateArgLists.addOuterTemplateArguments(Converted);
3806  InstantiateAttrsForDecl(TemplateArgLists,
3807  ClassTemplate->getTemplatedDecl(), Decl);
3808  }
3809  }
3810 
3811  // Diagnose uses of this specialization.
3812  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3813 
3814  CanonType = Context.getTypeDeclType(Decl);
3815  assert(isa<RecordType>(CanonType) &&
3816  "type of non-dependent specialization is not a RecordType");
3817  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3818  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3819  TemplateArgs);
3820  }
3821 
3822  // Build the fully-sugared type for this class template
3823  // specialization, which refers back to the class template
3824  // specialization we created or found.
3825  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3826 }
3827 
3829  TemplateNameKind &TNK,
3830  SourceLocation NameLoc,
3831  IdentifierInfo *&II) {
3832  assert(TNK == TNK_Undeclared_template && "not an undeclared template name");
3833 
3834  TemplateName Name = ParsedName.get();
3835  auto *ATN = Name.getAsAssumedTemplateName();
3836  assert(ATN && "not an assumed template name");
3837  II = ATN->getDeclName().getAsIdentifierInfo();
3838 
3839  if (!resolveAssumedTemplateNameAsType(S, Name, NameLoc, /*Diagnose*/false)) {
3840  // Resolved to a type template name.
3841  ParsedName = TemplateTy::make(Name);
3842  TNK = TNK_Type_template;
3843  }
3844 }
3845 
3847  SourceLocation NameLoc,
3848  bool Diagnose) {
3849  // We assumed this undeclared identifier to be an (ADL-only) function
3850  // template name, but it was used in a context where a type was required.
3851  // Try to typo-correct it now.
3852  AssumedTemplateStorage *ATN = Name.getAsAssumedTemplateName();
3853  assert(ATN && "not an assumed template name");
3854 
3855  LookupResult R(*this, ATN->getDeclName(), NameLoc, LookupOrdinaryName);
3856  struct CandidateCallback : CorrectionCandidateCallback {
3857  bool ValidateCandidate(const TypoCorrection &TC) override {
3858  return TC.getCorrectionDecl() &&
3860  }
3861  std::unique_ptr<CorrectionCandidateCallback> clone() override {
3862  return std::make_unique<CandidateCallback>(*this);
3863  }
3864  } FilterCCC;
3865 
3866  TypoCorrection Corrected =
3867  CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
3868  FilterCCC, CTK_ErrorRecovery);
3869  if (Corrected && Corrected.getFoundDecl()) {
3870  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest)
3871  << ATN->getDeclName());
3872  Name = TemplateName(Corrected.getCorrectionDeclAs<TemplateDecl>());
3873  return false;
3874  }
3875 
3876  if (Diagnose)
3877  Diag(R.getNameLoc(), diag::err_no_template) << R.getLookupName();
3878  return true;
3879 }
3880 
3882  Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
3883  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3884  SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
3885  ASTTemplateArgsPtr TemplateArgsIn, SourceLocation RAngleLoc,
3886  bool IsCtorOrDtorName, bool IsClassName) {
3887  if (SS.isInvalid())
3888  return true;
3889 
3890  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3891  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3892 
3893  // C++ [temp.res]p3:
3894  // A qualified-id that refers to a type and in which the
3895  // nested-name-specifier depends on a template-parameter (14.6.2)
3896  // shall be prefixed by the keyword typename to indicate that the
3897  // qualified-id denotes a type, forming an
3898  // elaborated-type-specifier (7.1.5.3).
3899  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3900  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3901  << SS.getScopeRep() << TemplateII->getName();
3902  // Recover as if 'typename' were specified.
3903  // FIXME: This is not quite correct recovery as we don't transform SS
3904  // into the corresponding dependent form (and we don't diagnose missing
3905  // 'template' keywords within SS as a result).
3906  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3907  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3908  TemplateArgsIn, RAngleLoc);
3909  }
3910 
3911  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3912  // it's not actually allowed to be used as a type in most cases. Because
3913  // we annotate it before we know whether it's valid, we have to check for
3914  // this case here.
3915  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3916  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3917  Diag(TemplateIILoc,
3918  TemplateKWLoc.isInvalid()
3919  ? diag::err_out_of_line_qualified_id_type_names_constructor
3920  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3921  << TemplateII << 0 /*injected-class-name used as template name*/
3922  << 1 /*if any keyword was present, it was 'template'*/;
3923  }
3924  }
3925 
3926  TemplateName Template = TemplateD.get();
3927  if (Template.getAsAssumedTemplateName() &&
3928  resolveAssumedTemplateNameAsType(S, Template, TemplateIILoc))
3929  return true;
3930 
3931  // Translate the parser's template argument list in our AST format.
3932  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3933  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3934 
3935  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3936  QualType T
3938  DTN->getQualifier(),
3939  DTN->getIdentifier(),
3940  TemplateArgs);
3941  // Build type-source information.
3942  TypeLocBuilder TLB;
3946  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3947  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3948  SpecTL.setTemplateNameLoc(TemplateIILoc);
3949  SpecTL.setLAngleLoc(LAngleLoc);
3950  SpecTL.setRAngleLoc(RAngleLoc);
3951  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3952  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3953  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3954  }
3955 
3956  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3957  if (Result.isNull())
3958  return true;
3959 
3960  // Build type-source information.
3961  TypeLocBuilder TLB;
3963  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3964  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3965  SpecTL.setTemplateNameLoc(TemplateIILoc);
3966  SpecTL.setLAngleLoc(LAngleLoc);
3967  SpecTL.setRAngleLoc(RAngleLoc);
3968  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3969  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3970 
3971  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3972  // constructor or destructor name (in such a case, the scope specifier
3973  // will be attached to the enclosing Decl or Expr node).
3974  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3975  // Create an elaborated-type-specifier containing the nested-name-specifier.
3976  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3977  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3979  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3980  }
3981 
3982  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3983 }
3984 
3986  TypeSpecifierType TagSpec,
3987  SourceLocation TagLoc,
3988  CXXScopeSpec &SS,
3989  SourceLocation TemplateKWLoc,
3990  TemplateTy TemplateD,
3991  SourceLocation TemplateLoc,
3992  SourceLocation LAngleLoc,
3993  ASTTemplateArgsPtr TemplateArgsIn,
3994  SourceLocation RAngleLoc) {
3995  if (SS.isInvalid())
3996  return TypeResult(true);
3997 
3998  TemplateName Template = TemplateD.get();
3999 
4000  // Translate the parser's template argument list in our AST format.
4001  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
4002  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
4003 
4004  // Determine the tag kind
4006  ElaboratedTypeKeyword Keyword
4008 
4009  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
4011  DTN->getQualifier(),
4012  DTN->getIdentifier(),
4013  TemplateArgs);
4014 
4015  // Build type-source information.
4016  TypeLocBuilder TLB;
4019  SpecTL.setElaboratedKeywordLoc(TagLoc);
4020  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
4021  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4022  SpecTL.setTemplateNameLoc(TemplateLoc);
4023  SpecTL.setLAngleLoc(LAngleLoc);
4024  SpecTL.setRAngleLoc(RAngleLoc);
4025  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
4026  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
4027  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
4028  }
4029 
4030  if (TypeAliasTemplateDecl *TAT =
4031  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
4032  // C++0x [dcl.type.elab]p2:
4033  // If the identifier resolves to a typedef-name or the simple-template-id
4034  // resolves to an alias template specialization, the
4035  // elaborated-type-specifier is ill-formed.
4036  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
4037  << TAT << NTK_TypeAliasTemplate << TagKind;
4038  Diag(TAT->getLocation(), diag::note_declared_at);
4039  }
4040 
4041  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
4042  if (Result.isNull())
4043  return TypeResult(true);
4044 
4045  // Check the tag kind
4046  if (const RecordType *RT = Result->getAs<RecordType>()) {
4047  RecordDecl *D = RT->getDecl();
4048 
4050  assert(Id && "templated class must have an identifier");
4051 
4052  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
4053  TagLoc, Id)) {
4054  Diag(TagLoc, diag::err_use_with_wrong_tag)
4055  << Result
4057  Diag(D->getLocation(), diag::note_previous_use);
4058  }
4059  }
4060 
4061  // Provide source-location information for the template specialization.
4062  TypeLocBuilder TLB;
4064  = TLB.push<TemplateSpecializationTypeLoc>(Result);
4065  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4066  SpecTL.setTemplateNameLoc(TemplateLoc);
4067  SpecTL.setLAngleLoc(LAngleLoc);
4068  SpecTL.setRAngleLoc(RAngleLoc);
4069  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
4070  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
4071 
4072  // Construct an elaborated type containing the nested-name-specifier (if any)
4073  // and tag keyword.
4074  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
4075  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
4076  ElabTL.setElaboratedKeywordLoc(TagLoc);
4077  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
4078  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
4079 }
4080 
4081 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
4082  NamedDecl *PrevDecl,
4083  SourceLocation Loc,
4085 
4087 
4089  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
4090  switch (Arg.getKind()) {
4097  return false;
4098 
4099  case TemplateArgument::Type: {
4100  QualType Type = Arg.getAsType();
4101  const TemplateTypeParmType *TPT =
4103  return TPT && !Type.hasQualifiers() &&
4104  TPT->getDepth() == Depth && TPT->getIndex() == Index;
4105  }
4106 
4108  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
4109  if (!DRE || !DRE->getDecl())
4110  return false;
4111  const NonTypeTemplateParmDecl *NTTP =
4112  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4113  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
4114  }
4115 
4117  const TemplateTemplateParmDecl *TTP =
4118  dyn_cast_or_null<TemplateTemplateParmDecl>(
4120  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
4121  }
4122  llvm_unreachable("unexpected kind of template argument");
4123 }
4124 
4127  if (Params->size() != Args.size())
4128  return false;
4129 
4130  unsigned Depth = Params->getDepth();
4131 
4132  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
4133  TemplateArgument Arg = Args[I];
4134 
4135  // If the parameter is a pack expansion, the argument must be a pack
4136  // whose only element is a pack expansion.
4137  if (Params->getParam(I)->isParameterPack()) {
4138  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
4139  !Arg.pack_begin()->isPackExpansion())
4140  return false;
4141  Arg = Arg.pack_begin()->getPackExpansionPattern();
4142  }
4143 
4145  return false;
4146  }
4147 
4148  return true;
4149 }
4150 
4151 template<typename PartialSpecDecl>
4152 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
4153  if (Partial->getDeclContext()->isDependentContext())
4154  return;
4155 
4156  // FIXME: Get the TDK from deduction in order to provide better diagnostics
4157  // for non-substitution-failure issues?
4158  TemplateDeductionInfo Info(Partial->getLocation());
4159  if (S.isMoreSpecializedThanPrimary(Partial, Info))
4160  return;
4161 
4162  auto *Template = Partial->getSpecializedTemplate();
4163  S.Diag(Partial->getLocation(),
4164  diag::ext_partial_spec_not_more_specialized_than_primary)
4165  << isa<VarTemplateDecl>(Template);
4166 
4167  if (Info.hasSFINAEDiagnostic()) {
4170  Info.takeSFINAEDiagnostic(Diag);
4171  SmallString<128> SFINAEArgString;
4172  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
4173  S.Diag(Diag.first,
4174  diag::note_partial_spec_not_more_specialized_than_primary)
4175  << SFINAEArgString;
4176  }
4177 
4178  S.Diag(Template->getLocation(), diag::note_template_decl_here);
4179  SmallVector<const Expr *, 3> PartialAC, TemplateAC;
4180  Template->getAssociatedConstraints(TemplateAC);
4181  Partial->getAssociatedConstraints(PartialAC);
4182  S.MaybeEmitAmbiguousAtomicConstraintsDiagnostic(Partial, PartialAC, Template,
4183  TemplateAC);
4184 }
4185 
4186 static void
4188  const llvm::SmallBitVector &DeducibleParams) {
4189  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
4190  if (!DeducibleParams[I]) {
4191  NamedDecl *Param = TemplateParams->getParam(I);
4192  if (Param->getDeclName())
4193  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4194  << Param->getDeclName();
4195  else
4196  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4197  << "(anonymous)";
4198  }
4199  }
4200 }
4201 
4202 
4203 template<typename PartialSpecDecl>
4205  PartialSpecDecl *Partial) {
4206  // C++1z [temp.class.spec]p8: (DR1495)
4207  // - The specialization shall be more specialized than the primary
4208  // template (14.5.5.2).
4209  checkMoreSpecializedThanPrimary(S, Partial);
4210 
4211  // C++ [temp.class.spec]p8: (DR1315)
4212  // - Each template-parameter shall appear at least once in the
4213  // template-id outside a non-deduced context.
4214  // C++1z [temp.class.spec.match]p3 (P0127R2)
4215  // If the template arguments of a partial specialization cannot be
4216  // deduced because of the structure of its template-parameter-list
4217  // and the template-id, the program is ill-formed.
4218  auto *TemplateParams = Partial->getTemplateParameters();
4219  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4220  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
4221  TemplateParams->getDepth(), DeducibleParams);
4222 
4223  if (!DeducibleParams.all()) {
4224  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4225  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
4226  << isa<VarTemplatePartialSpecializationDecl>(Partial)
4227  << (NumNonDeducible > 1)
4228  << SourceRange(Partial->getLocation(),
4229  Partial->getTemplateArgsAsWritten()->RAngleLoc);
4230  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
4231  }
4232 }
4233 
4236  checkTemplatePartialSpecialization(*this, Partial);
4237 }
4238 
4241  checkTemplatePartialSpecialization(*this, Partial);
4242 }
4243 
4245  // C++1z [temp.param]p11:
4246  // A template parameter of a deduction guide template that does not have a
4247  // default-argument shall be deducible from the parameter-type-list of the
4248  // deduction guide template.
4249  auto *TemplateParams = TD->getTemplateParameters();
4250  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4251  MarkDeducedTemplateParameters(TD, DeducibleParams);
4252  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
4253  // A parameter pack is deducible (to an empty pack).
4254  auto *Param = TemplateParams->getParam(I);
4255  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
4256  DeducibleParams[I] = true;
4257  }
4258 
4259  if (!DeducibleParams.all()) {
4260  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4261  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
4262  << (NumNonDeducible > 1);
4263  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
4264  }
4265 }
4266 
4268  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
4269  TemplateParameterList *TemplateParams, StorageClass SC,
4270  bool IsPartialSpecialization) {
4271  // D must be variable template id.
4273  "Variable template specialization is declared with a template it.");
4274 
4275  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
4276  TemplateArgumentListInfo TemplateArgs =
4277  makeTemplateArgumentListInfo(*this, *TemplateId);
4278  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
4279  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
4280  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
4281 
4282  TemplateName Name = TemplateId->Template.get();
4283 
4284  // The template-id must name a variable template.
4285  VarTemplateDecl *VarTemplate =
4286  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
4287  if (!VarTemplate) {
4288  NamedDecl *FnTemplate;
4289  if (auto *OTS = Name.getAsOverloadedTemplate())
4290  FnTemplate = *OTS->begin();
4291  else
4292  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
4293  if (FnTemplate)
4294  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
4295  << FnTemplate->getDeclName();
4296  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
4298  }
4299 
4300  // Check for unexpanded parameter packs in any of the template arguments.
4301  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
4302  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
4303  UPPC_PartialSpecialization))
4304  return true;
4305 
4306  // Check that the template argument list is well-formed for this
4307  // template.
4309  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
4310  false, Converted,
4311  /*UpdateArgsWithConversion=*/true))
4312  return true;
4313 
4314  // Find the variable template (partial) specialization declaration that
4315  // corresponds to these arguments.
4317  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
4318  TemplateArgs.size(), Converted))
4319  return true;
4320 
4321  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
4322  // also do them during instantiation.
4323  if (!Name.isDependent() &&
4325  Converted)) {
4326  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
4327  << VarTemplate->getDeclName();
4328  IsPartialSpecialization = false;
4329  }
4330 
4332  Converted) &&
4333  (!Context.getLangOpts().CPlusPlus20 ||
4334  !TemplateParams->hasAssociatedConstraints())) {
4335  // C++ [temp.class.spec]p9b3:
4336  //
4337  // -- The argument list of the specialization shall not be identical
4338  // to the implicit argument list of the primary template.
4339  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
4340  << /*variable template*/ 1
4341  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
4342  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
4343  // FIXME: Recover from this by treating the declaration as a redeclaration
4344  // of the primary template.
4345  return true;
4346  }
4347  }
4348 
4349  void *InsertPos = nullptr;
4350  VarTemplateSpecializationDecl *PrevDecl = nullptr;
4351 
4353  PrevDecl = VarTemplate->findPartialSpecialization(Converted, TemplateParams,
4354  InsertPos);
4355  else
4356  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
4357 
4359 
4360  // Check whether we can declare a variable template specialization in
4361  // the current scope.
4362  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
4363  TemplateNameLoc,
4365  return true;
4366 
4367  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
4368  // Since the only prior variable template specialization with these
4369  // arguments was referenced but not declared, reuse that
4370  // declaration node as our own, updating its source location and
4371  // the list of outer template parameters to reflect our new declaration.
4372  Specialization = PrevDecl;
4373  Specialization->setLocation(TemplateNameLoc);
4374  PrevDecl = nullptr;
4375  } else if (IsPartialSpecialization) {
4376  // Create a new class template partial specialization declaration node.
4378  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
4381  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
4382  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
4383  Converted, TemplateArgs);
4384 
4385  if (!PrevPartial)
4386  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
4387  Specialization = Partial;
4388 
4389  // If we are providing an explicit specialization of a member variable
4390  // template specialization, make a note of that.
4391  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
4392  PrevPartial->setMemberSpecialization();
4393 
4394  CheckTemplatePartialSpecialization(Partial);
4395  } else {
4396  // Create a new class template specialization declaration node for
4397  // this explicit specialization or friend declaration.
4399  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
4400  VarTemplate, DI->getType(), DI, SC, Converted);
4401  Specialization->setTemplateArgsInfo(TemplateArgs);
4402 
4403  if (!PrevDecl)
4404  VarTemplate->AddSpecialization(Specialization, InsertPos);
4405  }
4406 
4407  // C++ [temp.expl.spec]p6:
4408  // If a template, a member template or the member of a class template is
4409  // explicitly specialized then that specialization shall be declared
4410  // before the first use of that specialization that would cause an implicit
4411  // instantiation to take place, in every translation unit in which such a
4412  // use occurs; no diagnostic is required.
4413  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
4414  bool Okay = false;
4415  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
4416  // Is there any previous explicit specialization declaration?
4418  Okay = true;
4419  break;
4420  }
4421  }
4422 
4423  if (!Okay) {
4424  SourceRange Range(TemplateNameLoc, RAngleLoc);
4425  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
4426  << Name << Range;
4427 
4428  Diag(PrevDecl->getPointOfInstantiation(),
4429  diag::note_instantiation_required_here)
4430  << (PrevDecl->getTemplateSpecializationKind() !=
4432  return true;
4433  }
4434  }
4435 
4436  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
4437  Specialization->setLexicalDeclContext(CurContext);
4438 
4439  // Add the specialization into its lexical context, so that it can
4440  // be seen when iterating through the list of declarations in that
4441  // context. However, specializations are not found by name lookup.
4442  CurContext->addDecl(Specialization);
4443 
4444  // Note that this is an explicit specialization.
4445  Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
4446 
4447  if (PrevDecl) {
4448  // Check that this isn't a redefinition of this specialization,
4449  // merging with previous declarations.
4450  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
4451  forRedeclarationInCurContext());
4452  PrevSpec.addDecl(PrevDecl);
4453  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
4454  } else if (Specialization->isStaticDataMember() &&
4455  Specialization->isOutOfLine()) {
4456  Specialization->setAccess(VarTemplate->getAccess());
4457  }
4458 
4459  return Specialization;
4460 }
4461 
4462 namespace {
4463 /// A partial specialization whose template arguments have matched
4464 /// a given template-id.
4465 struct PartialSpecMatchResult {
4467  TemplateArgumentList *Args;
4468 };
4469 } // end anonymous namespace
4470 
4471 DeclResult
4473  SourceLocation TemplateNameLoc,
4474  const TemplateArgumentListInfo &TemplateArgs) {
4475  assert(Template && "A variable template id without template?");
4476 
4477  // Check that the template argument list is well-formed for this template.
4479  if (CheckTemplateArgumentList(
4480  Template, TemplateNameLoc,
4481  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
4482  Converted, /*UpdateArgsWithConversion=*/true))
4483  return true;
4484 
4485  // Produce a placeholder value if the specialization is dependent.
4486  if (Template->getDeclContext()->isDependentContext() ||
4488  Converted))
4489  return DeclResult();
4490 
4491  // Find the variable template specialization declaration that
4492  // corresponds to these arguments.
4493  void *InsertPos = nullptr;
4494  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
4495  Converted, InsertPos)) {
4496  checkSpecializationVisibility(TemplateNameLoc, Spec);
4497  // If we already have a variable template specialization, return it.
4498  return Spec;
4499  }
4500 
4501  // This is the first time we have referenced this variable template
4502  // specialization. Create the canonical declaration and add it to
4503  // the set of specializations, based on the closest partial specialization
4504  // that it represents. That is,
4505  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
4507  Converted);
4508  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
4509  bool AmbiguousPartialSpec = false;
4510  typedef PartialSpecMatchResult MatchResult;
4512  SourceLocation PointOfInstantiation = TemplateNameLoc;
4513  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
4514  /*ForTakingAddress=*/false);
4515 
4516  // 1. Attempt to find the closest partial specialization that this
4517  // specializes, if any.
4518  // TODO: Unify with InstantiateClassTemplateSpecialization()?
4519  // Perhaps better after unification of DeduceTemplateArguments() and
4520  // getMoreSpecializedPartialSpecialization().
4522  Template->getPartialSpecializations(PartialSpecs);
4523 
4524  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
4525  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
4526  TemplateDeductionInfo Info(FailedCandidates.getLocation());
4527 
4528  if (TemplateDeductionResult Result =
4529  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
4530  // Store the failed-deduction information for use in diagnostics, later.
4531  // TODO: Actually use the failed-deduction info?
4532  FailedCandidates.addCandidate().set(
4533  DeclAccessPair::make(Template, AS_public), Partial,
4534  MakeDeductionFailureInfo(Context, Result, Info));
4535  (void)Result;
4536  } else {
4537  Matched.push_back(PartialSpecMatchResult());
4538  Matched.back().Partial = Partial;
4539  Matched.back().Args = Info.take();
4540  }
4541  }
4542 
4543  if (Matched.size() >= 1) {
4544  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
4545  if (Matched.size() == 1) {
4546  // -- If exactly one matching specialization is found, the
4547  // instantiation is generated from that specialization.
4548  // We don't need to do anything for this.
4549  } else {
4550  // -- If more than one matching specialization is found, the
4551  // partial order rules (14.5.4.2) are used to determine
4552  // whether one of the specializations is more specialized
4553  // than the others. If none of the specializations is more
4554  // specialized than all of the other matching
4555  // specializations, then the use of the variable template is
4556  // ambiguous and the program is ill-formed.
4557  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4558  PEnd = Matched.end();
4559  P != PEnd; ++P) {
4560  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4561  PointOfInstantiation) ==
4562  P->Partial)
4563  Best = P;
4564  }
4565 
4566  // Determine if the best partial specialization is more specialized than
4567  // the others.
4568  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4569  PEnd = Matched.end();
4570  P != PEnd; ++P) {
4571  if (P != Best && getMoreSpecializedPartialSpecialization(
4572  P->Partial, Best->Partial,
4573  PointOfInstantiation) != Best->Partial) {
4574  AmbiguousPartialSpec = true;
4575  break;
4576  }
4577  }
4578  }
4579 
4580  // Instantiate using the best variable template partial specialization.
4581  InstantiationPattern = Best->Partial;
4582  InstantiationArgs = Best->Args;
4583  } else {
4584  // -- If no match is found, the instantiation is generated
4585  // from the primary template.
4586  // InstantiationPattern = Template->getTemplatedDecl();
4587  }
4588 
4589  // 2. Create the canonical declaration.
4590  // Note that we do not instantiate a definition until we see an odr-use
4591  // in DoMarkVarDeclReferenced().
4592  // FIXME: LateAttrs et al.?
4593  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4594  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4595  Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
4596  if (!Decl)
4597  return true;
4598 
4599  if (AmbiguousPartialSpec) {
4600  // Partial ordering did not produce a clear winner. Complain.
4601  Decl->setInvalidDecl();
4602  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4603  << Decl;
4604 
4605  // Print the matching partial specializations.
4606  for (MatchResult P : Matched)
4607  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4608  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4609  *P.Args);
4610  return true;
4611  }
4612 
4614  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4615  Decl->setInstantiationOf(D, InstantiationArgs);
4616 
4617  checkSpecializationVisibility(TemplateNameLoc, Decl);
4618 
4619  assert(Decl && "No variable template specialization?");
4620  return Decl;
4621 }
4622 
4623 ExprResult
4625  const DeclarationNameInfo &NameInfo,
4626  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4627  const TemplateArgumentListInfo *TemplateArgs) {
4628 
4629  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4630  *TemplateArgs);
4631  if (Decl.isInvalid())
4632  return ExprError();
4633 
4634  if (!Decl.get())
4635  return ExprResult();
4636 
4637  VarDecl *Var = cast<VarDecl>(Decl.get());
4638  if (!Var->getTemplateSpecializationKind())
4640  NameInfo.getLoc());
4641 
4642  // Build an ordinary singleton decl ref.
4643  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4644  /*FoundD=*/nullptr, TemplateArgs);
4645 }
4646 
4648  SourceLocation Loc) {
4649  Diag(Loc, diag::err_template_missing_args)
4650  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4651  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4652  Diag(TD->getLocation(), diag::note_template_decl_here)
4653  << TD->getTemplateParameters()->getSourceRange();
4654  }
4655 }
4656 
4657 ExprResult
4659  SourceLocation TemplateKWLoc,
4660  const DeclarationNameInfo &ConceptNameInfo,
4661  NamedDecl *FoundDecl,
4662  ConceptDecl *NamedConcept,
4663  const TemplateArgumentListInfo *TemplateArgs) {
4664  assert(NamedConcept && "A concept template id without a template?");
4665 
4667  if (CheckTemplateArgumentList(NamedConcept, ConceptNameInfo.getLoc(),
4668  const_cast<TemplateArgumentListInfo&>(*TemplateArgs),
4669  /*PartialTemplateArgs=*/false, Converted,
4670  /*UpdateArgsWithConversion=*/false))
4671  return ExprError();
4672 
4673  ConstraintSatisfaction Satisfaction;
4674  bool AreArgsDependent =
4676  Converted);
4677  if (!AreArgsDependent &&
4679  NamedConcept, {NamedConcept->getConstraintExpr()}, Converted,
4680  SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameInfo.getLoc(),
4681  TemplateArgs->getRAngleLoc()),
4682  Satisfaction))
4683  return ExprError();
4684 
4685  return ConceptSpecializationExpr::Create(Context,
4686  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
4687  TemplateKWLoc, ConceptNameInfo, FoundDecl, NamedConcept,
4688  ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
4689  AreArgsDependent ? nullptr : &Satisfaction);
4690 }
4691 
4693  SourceLocation TemplateKWLoc,
4694  LookupResult &R,
4695  bool RequiresADL,
4696  const TemplateArgumentListInfo *TemplateArgs) {
4697  // FIXME: Can we do any checking at this point? I guess we could check the
4698  // template arguments that we have against the template name, if the template
4699  // name refers to a single template. That's not a terribly common case,
4700  // though.
4701  // foo<int> could identify a single function unambiguously
4702  // This approach does NOT work, since f<int>(1);
4703  // gets resolved prior to resorting to overload resolution
4704  // i.e., template<class T> void f(double);
4705  // vs template<class T, class U> void f(U);
4706 
4707  // These should be filtered out by our callers.
4708  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4709 
4710  // Non-function templates require a template argument list.
4711  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4712  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4713  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4714  return ExprError();
4715  }
4716  }
4717 
4718  // In C++1y, check variable template ids.
4719  if (R.getAsSingle<VarTemplateDecl>()) {
4720  ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
4722  TemplateKWLoc, TemplateArgs);
4723  if (Res.isInvalid() || Res.isUsable())
4724  return Res;
4725  // Result is dependent. Carry on to build an UnresolvedLookupEpxr.
4726  }
4727 
4728  if (R.getAsSingle<ConceptDecl>()) {
4729  return CheckConceptTemplateId(SS, TemplateKWLoc, R.getLookupNameInfo(),
4730  R.getFoundDecl(),
4731  R.getAsSingle<ConceptDecl>(), TemplateArgs);
4732  }
4733 
4734  // We don't want lookup warnings at this point.
4735  R.suppressDiagnostics();
4736 
4739  SS.getWithLocInContext(Context),
4740  TemplateKWLoc,
4741  R.getLookupNameInfo(),
4742  RequiresADL, TemplateArgs,
4743  R.begin(), R.end());
4744 
4745  return ULE;
4746 }
4747 
4748 // We actually only call this from template instantiation.
4749 ExprResult
4751  SourceLocation TemplateKWLoc,
4752  const DeclarationNameInfo &NameInfo,
4753  const TemplateArgumentListInfo *TemplateArgs) {
4754 
4755  assert(TemplateArgs || TemplateKWLoc.isValid());
4756  DeclContext *DC;
4757  if (!(DC = computeDeclContext(SS, false)) ||
4758  DC->isDependentContext() ||
4759  RequireCompleteDeclContext(SS, DC))
4760  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4761 
4762  bool MemberOfUnknownSpecialization;
4763  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4764  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4765  /*Entering*/false, MemberOfUnknownSpecialization,
4766  TemplateKWLoc))
4767  return ExprError();
4768 
4769  if (R.isAmbiguous())
4770  return ExprError();
4771 
4772  if (R.empty()) {
4773  Diag(NameInfo.getLoc(), diag::err_no_member)
4774  << NameInfo.getName() << DC << SS.getRange();
4775  return ExprError();
4776  }
4777 
4778  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4779  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4780  << SS.getScopeRep()
4781  << NameInfo.getName().getAsString() << SS.getRange();
4782  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4783  return ExprError();
4784  }
4785 
4786  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4787 }
4788 
4789 /// Form a template name from a name that is syntactically required to name a
4790 /// template, either due to use of the 'template' keyword or because a name in
4791 /// this syntactic context is assumed to name a template (C++ [temp.names]p2-4).
4792 ///
4793 /// This action forms a template name given the name of the template and its
4794 /// optional scope specifier. This is used when the 'template' keyword is used
4795 /// or when the parsing context unambiguously treats a following '<' as
4796 /// introducing a template argument list. Note that this may produce a
4797 /// non-dependent template name if we can perform the lookup now and identify
4798 /// the named template.
4799 ///
4800 /// For example, given "x.MetaFun::template apply", the scope specifier
4801 /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
4802 /// of the "template" keyword, and "apply" is the \p Name.
4804  CXXScopeSpec &SS,
4805  SourceLocation TemplateKWLoc,
4806  const UnqualifiedId &Name,
4807  ParsedType ObjectType,
4808  bool EnteringContext,
4809  TemplateTy &Result,
4810  bool AllowInjectedClassName) {
4811  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4812  Diag(TemplateKWLoc,
4813  getLangOpts().CPlusPlus11 ?
4814  diag::warn_cxx98_compat_template_outside_of_template :
4815  diag::ext_template_outside_of_template)
4816  << FixItHint::CreateRemoval(TemplateKWLoc);
4817 
4818  if (SS.isInvalid())
4819  return TNK_Non_template;
4820 
4821  // Figure out where isTemplateName is going to look.
4822  DeclContext *LookupCtx = nullptr;
4823  if (SS.isNotEmpty())
4824  LookupCtx = computeDeclContext(SS, EnteringContext);
4825  else if (ObjectType)
4826  LookupCtx = computeDeclContext(GetTypeFromParser(ObjectType));
4827 
4828  // C++0x [temp.names]p5:
4829  // If a name prefixed by the keyword template is not the name of
4830  // a template, the program is ill-formed. [Note: the keyword
4831  // template may not be applied to non-template members of class
4832  // templates. -end note ] [ Note: as is the case with the
4833  // typename prefix, the template prefix is allowed in cases
4834  // where it is not strictly necessary; i.e., when the
4835  // nested-name-specifier or the expression on the left of the ->
4836  // or . is not dependent on a template-parameter, or the use
4837  // does not appear in the scope of a template. -end note]
4838  //
4839  // Note: C++03 was more strict here, because it banned the use of
4840  // the "template" keyword prior to a template-name that was not a
4841  // dependent name. C++ DR468 relaxed this requirement (the
4842  // "template" keyword is now permitted). We follow the C++0x
4843  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4844  bool MemberOfUnknownSpecialization;
4845  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4846  ObjectType, EnteringContext, Result,
4847  MemberOfUnknownSpecialization);
4848  if (TNK != TNK_Non_template) {
4849  // We resolved this to a (non-dependent) template name. Return it.
4850  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
4851  if (!AllowInjectedClassName && SS.isNotEmpty() && LookupRD &&
4852  Name.getKind() == UnqualifiedIdKind::IK_Identifier &&
4853  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4854  // C++14 [class.qual]p2:
4855  // In a lookup in which function names are not ignored and the
4856  // nested-name-specifier nominates a class C, if the name specified
4857  // [...] is the injected-class-name of C, [...] the name is instead
4858  // considered to name the constructor
4859  //
4860  // We don't get here if naming the constructor would be valid, so we
4861  // just reject immediately and recover by treating the
4862  // injected-class-name as naming the template.
4863  Diag(Name.getBeginLoc(),
4864  diag::ext_out_of_line_qualified_id_type_names_constructor)
4865  << Name.Identifier
4866  << 0 /*injected-class-name used as template name*/
4867  << TemplateKWLoc.isValid();
4868  }
4869  return TNK;
4870  }
4871 
4872  if (!MemberOfUnknownSpecialization) {
4873  // Didn't find a template name, and the lookup wasn't dependent.
4874  // Do the lookup again to determine if this is a "nothing found" case or
4875  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4876  // need to do this.
4877  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4878  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4879  LookupOrdinaryName);
4880  bool MOUS;
4881  // Tell LookupTemplateName that we require a template so that it diagnoses
4882  // cases where it finds a non-template.
4883  RequiredTemplateKind RTK = TemplateKWLoc.isValid()
4884  ? RequiredTemplateKind(TemplateKWLoc)
4885  : TemplateNameIsRequired;
4886  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext, MOUS,
4887  RTK, nullptr, /*AllowTypoCorrection=*/false) &&
4888  !R.isAmbiguous()) {
4889  if (LookupCtx)
4890  Diag(Name.getBeginLoc(), diag::err_no_member)
4891  << DNI.getName() << LookupCtx << SS.getRange();
4892  else
4893  Diag(Name.getBeginLoc(), diag::err_undeclared_use)
4894  << DNI.getName() << SS.getRange();
4895  }
4896  return TNK_Non_template;
4897  }
4898 
4899  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4900 
4901  switch (Name.getKind()) {
4903  Result = TemplateTy::make(
4904  Context.getDependentTemplateName(Qualifier, Name.Identifier));
4906 
4908  Result = TemplateTy::make(Context.getDependentTemplateName(
4909  Qualifier, Name.OperatorFunctionId.Operator));
4910  return TNK_Function_template;
4911 
4913  // This is a kind of template name, but can never occur in a dependent
4914  // scope (literal operators can only be declared at namespace scope).
4915  break;
4916 
4917  default:
4918  break;
4919  }
4920 
4921  // This name cannot possibly name a dependent template. Diagnose this now
4922  // rather than building a dependent template name that can never be valid.
4923  Diag(Name.getBeginLoc(),
4924  diag::err_template_kw_refers_to_dependent_non_template)
4925  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4926  << TemplateKWLoc.isValid() << TemplateKWLoc;
4927  return TNK_Non_template;
4928 }
4929 
4931  TemplateArgumentLoc &AL,
4932  SmallVectorImpl<TemplateArgument> &Converted) {
4933  const TemplateArgument &Arg = AL.getArgument();
4934  QualType ArgType;
4935  TypeSourceInfo *TSI = nullptr;
4936 
4937  // Check template type parameter.
4938  switch(Arg.getKind()) {
4940  // C++ [temp.arg.type]p1:
4941  // A template-argument for a template-parameter which is a
4942  // type shall be a type-id.
4943  ArgType = Arg.getAsType();
4944  TSI = AL.getTypeSourceInfo();
4945  break;
4948  // We have a template type parameter but the template argument
4949  // is a template without any arguments.
4950  SourceRange SR = AL.getSourceRange();
4952  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4953  return true;
4954  }
4956  // We have a template type parameter but the template argument is an
4957  // expression; see if maybe it is missing the "typename" keyword.
4958  CXXScopeSpec SS;
4959  DeclarationNameInfo NameInfo;
4960 
4961  if (DependentScopeDeclRefExpr *ArgExpr =
4962  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4963  SS.Adopt(ArgExpr->getQualifierLoc());
4964  NameInfo = ArgExpr->getNameInfo();
4965  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4966  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4967  if (ArgExpr->isImplicitAccess()) {
4968  SS.Adopt(ArgExpr->getQualifierLoc());
4969  NameInfo = ArgExpr->getMemberNameInfo();
4970  }
4971  }
4972 
4973  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4974  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4975  LookupParsedName(Result, CurScope, &SS);
4976 
4977  if (Result.getAsSingle<TypeDecl>() ||
4978  Result.getResultKind() ==
4980  assert(SS.getScopeRep() && "dependent scope expr must has a scope!");
4981  // Suggest that the user add 'typename' before the NNS.
4982  SourceLocation Loc = AL.getSourceRange().getBegin();
4983  Diag(Loc, getLangOpts().MSVCCompat
4984  ? diag::ext_ms_template_type_arg_missing_typename
4985  : diag::err_template_arg_must_be_type_suggest)
4986  << FixItHint::CreateInsertion(Loc, "typename ");
4987  Diag(Param->getLocation(), diag::note_template_param_here);
4988 
4989  // Recover by synthesizing a type using the location information that we
4990  // already have.
4991  ArgType =
4992  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
4993  TypeLocBuilder TLB;
4994  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
4995  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
4996  TL.setQualifierLoc(SS.getWithLocInContext(Context));
4997  TL.setNameLoc(NameInfo.getLoc());
4998  TSI = TLB.getTypeSourceInfo(Context, ArgType);
4999 
5000  // Overwrite our input TemplateArgumentLoc so that we can recover
5001  // properly.
5002  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
5004 
5005  break;
5006  }
5007  }
5008  // fallthrough
5009  LLVM_FALLTHROUGH;
5010  }
5011  default: {
5012  // We have a template type parameter but the template argument
5013  // is not a type.
5014  SourceRange SR = AL.getSourceRange();
5015  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
5016  Diag(Param->getLocation(), diag::note_template_param_here);
5017 
5018  return true;
5019  }
5020  }
5021 
5022  if (CheckTemplateArgument(Param, TSI))
5023  return true;
5024 
5025  // Add the converted template type argument.
5026  ArgType = Context.getCanonicalType(ArgType);
5027 
5028  // Objective-C ARC:
5029  // If an explicitly-specified template argument type is a lifetime type
5030  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
5031  if (getLangOpts().ObjCAutoRefCount &&
5032  ArgType->isObjCLifetimeType() &&
5033  !ArgType.getObjCLifetime()) {
5034  Qualifiers Qs;
5036  ArgType = Context.getQualifiedType(ArgType, Qs);
5037  }
5038 
5039  Converted.push_back(TemplateArgument(ArgType));
5040  return false;
5041 }
5042 
5043 /// Substitute template arguments into the default template argument for
5044 /// the given template type parameter.
5045 ///
5046 /// \param SemaRef the semantic analysis object for which we are performing
5047 /// the substitution.
5048 ///
5049 /// \param Template the template that we are synthesizing template arguments
5050 /// for.
5051 ///
5052 /// \param TemplateLoc the location of the template name that started the
5053 /// template-id we are checking.
5054 ///
5055 /// \param RAngleLoc the location of the right angle bracket ('>') that
5056 /// terminates the template-id.
5057 ///
5058 /// \param Param the template template parameter whose default we are
5059 /// substituting into.
5060 ///
5061 /// \param Converted the list of template arguments provided for template
5062 /// parameters that precede \p Param in the template parameter list.
5063 /// \returns the substituted template argument, or NULL if an error occurred.
5064 static TypeSourceInfo *
5066  TemplateDecl *Template,
5067  SourceLocation TemplateLoc,
5068  SourceLocation RAngleLoc,
5069  TemplateTypeParmDecl *Param,
5070  SmallVectorImpl<TemplateArgument> &Converted) {
5071  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
5072 
5073  // If the argument type is dependent, instantiate it now based
5074  // on the previously-computed template arguments.
5075  if (ArgType->getType()->isInstantiationDependentType()) {
5076  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5077  Param, Template, Converted,
5078  SourceRange(TemplateLoc, RAngleLoc));
5079  if (Inst.isInvalid())
5080  return nullptr;
5081 
5082  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5083 
5084  // Only substitute for the innermost template argument list.
5085  MultiLevelTemplateArgumentList TemplateArgLists;
5086  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5087  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5088  TemplateArgLists.addOuterTemplateArguments(None);
5089 
5090  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5091  ArgType =
5092  SemaRef.SubstType(ArgType, TemplateArgLists,
5093  Param->getDefaultArgumentLoc(), Param->getDeclName());
5094  }
5095 
5096  return ArgType;
5097 }
5098 
5099 /// Substitute template arguments into the default template argument for
5100 /// the given non-type template parameter.
5101 ///
5102 /// \param SemaRef the semantic analysis object for which we are performing
5103 /// the substitution.
5104 ///
5105 /// \param Template the template that we are synthesizing template arguments
5106 /// for.
5107 ///
5108 /// \param TemplateLoc the location of the template name that started the
5109 /// template-id we are checking.
5110 ///
5111 /// \param RAngleLoc the location of the right angle bracket ('>') that
5112 /// terminates the template-id.
5113 ///
5114 /// \param Param the non-type template parameter whose default we are
5115 /// substituting into.
5116 ///
5117 /// \param Converted the list of template arguments provided for template
5118 /// parameters that precede \p Param in the template parameter list.
5119 ///
5120 /// \returns the substituted template argument, or NULL if an error occurred.
5121 static ExprResult
5123  TemplateDecl *Template,
5124  SourceLocation TemplateLoc,
5125  SourceLocation RAngleLoc,
5126  NonTypeTemplateParmDecl *Param,
5127  SmallVectorImpl<TemplateArgument> &Converted) {
5128  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5129  Param, Template, Converted,
5130  SourceRange(TemplateLoc, RAngleLoc));
5131  if (Inst.isInvalid())
5132  return ExprError();
5133 
5134  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5135 
5136  // Only substitute for the innermost template argument list.
5137  MultiLevelTemplateArgumentList TemplateArgLists;
5138  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5139  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5140  TemplateArgLists.addOuterTemplateArguments(None);
5141 
5142  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5143  EnterExpressionEvaluationContext ConstantEvaluated(
5145  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
5146 }
5147 
5148 /// Substitute template arguments into the default template argument for
5149 /// the given template template parameter.
5150 ///
5151 /// \param SemaRef the semantic analysis object for which we are performing
5152 /// the substitution.
5153 ///
5154 /// \param Template the template that we are synthesizing template arguments
5155 /// for.
5156 ///
5157 /// \param TemplateLoc the location of the template name that started the
5158 /// template-id we are checking.
5159 ///
5160 /// \param RAngleLoc the location of the right angle bracket ('>') that
5161 /// terminates the template-id.
5162 ///
5163 /// \param Param the template template parameter whose default we are
5164 /// substituting into.
5165 ///
5166 /// \param Converted the list of template arguments provided for template
5167 /// parameters that precede \p Param in the template parameter list.
5168 ///
5169 /// \param QualifierLoc Will be set to the nested-name-specifier (with
5170 /// source-location information) that precedes the template name.
5171 ///
5172 /// \returns the substituted template argument, or NULL if an error occurred.
5173 static TemplateName
5175  TemplateDecl *Template,
5176  SourceLocation TemplateLoc,
5177  SourceLocation RAngleLoc,
5178  TemplateTemplateParmDecl *Param,
5180  NestedNameSpecifierLoc &QualifierLoc) {
5182  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
5183  SourceRange(TemplateLoc, RAngleLoc));
5184  if (Inst.isInvalid())
5185  return TemplateName();
5186 
5187  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5188 
5189  // Only substitute for the innermost template argument list.
5190  MultiLevelTemplateArgumentList TemplateArgLists;
5191  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5192  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5193  TemplateArgLists.addOuterTemplateArguments(None);
5194 
5195  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5196  // Substitute into the nested-name-specifier first,
5197  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
5198  if (QualifierLoc) {
5199  QualifierLoc =
5200  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
5201  if (!QualifierLoc)
5202  return TemplateName();
5203  }
5204 
5205  return SemaRef.SubstTemplateName(
5206  QualifierLoc,
5209  TemplateArgLists);
5210 }
5211 
5212 /// If the given template parameter has a default template
5213 /// argument, substitute into that default template argument and
5214 /// return the corresponding template argument.
5217  SourceLocation TemplateLoc,
5218  SourceLocation RAngleLoc,
5219  Decl *Param,
5221  &Converted,
5222  bool &HasDefaultArg) {
5223  HasDefaultArg = false;
5224 
5225  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
5226  if (!hasVisibleDefaultArgument(TypeParm))
5227  return TemplateArgumentLoc();
5228 
5229  HasDefaultArg = true;
5230  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
5231  TemplateLoc,
5232  RAngleLoc,
5233  TypeParm,
5234  Converted);
5235  if (DI)
5236  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
5237 
5238  return TemplateArgumentLoc();
5239  }
5240 
5241  if (NonTypeTemplateParmDecl *NonTypeParm
5242  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5243  if (!hasVisibleDefaultArgument(NonTypeParm))
5244  return TemplateArgumentLoc();
5245 
5246  HasDefaultArg = true;
5247  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
5248  TemplateLoc,
5249  RAngleLoc,
5250  NonTypeParm,
5251  Converted);
5252  if (Arg.isInvalid())
5253  return TemplateArgumentLoc();
5254 
5255  Expr *ArgE = Arg.getAs<Expr>();
5256  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
5257  }
5258 
5259  TemplateTemplateParmDecl *TempTempParm
5260  = cast<TemplateTemplateParmDecl>(Param);
5261  if (!hasVisibleDefaultArgument(TempTempParm))
5262  return TemplateArgumentLoc();
5263 
5264  HasDefaultArg = true;
5265  NestedNameSpecifierLoc QualifierLoc;
5266  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
5267  TemplateLoc,
5268  RAngleLoc,
5269  TempTempParm,
5270  Converted,
5271  QualifierLoc);
5272  if (TName.isNull())
5273  return TemplateArgumentLoc();
5274 
5275  return TemplateArgumentLoc(
5276  Context, TemplateArgument(TName),
5277  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
5278  TempTempParm->getDefaultArgument().getTemplateNameLoc());
5279 }
5280 
5281 /// Convert a template-argument that we parsed as a type into a template, if
5282 /// possible. C++ permits injected-class-names to perform dual service as
5283 /// template template arguments and as template type arguments.
5284 static TemplateArgumentLoc
5286  // Extract and step over any surrounding nested-name-specifier.
5287  NestedNameSpecifierLoc QualLoc;
5288  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
5289  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
5290  return TemplateArgumentLoc();
5291 
5292  QualLoc = ETLoc.getQualifierLoc();
5293  TLoc = ETLoc.getNamedTypeLoc();
5294  }
5295  // If this type was written as an injected-class-name, it can be used as a
5296  // template template argument.
5297  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
5298  return TemplateArgumentLoc(Context, InjLoc.getTypePtr()->getTemplateName(),
5299  QualLoc, InjLoc.getNameLoc());
5300 
5301  // If this type was written as an injected-class-name, it may have been
5302  // converted to a RecordType during instantiation. If the RecordType is
5303  // *not* wrapped in a TemplateSpecializationType and denotes a class
5304  // template specialization, it must have come from an injected-class-name.
5305  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
5306  if (auto *CTSD =
5307  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
5308  return TemplateArgumentLoc(Context,
5309  TemplateName(CTSD->getSpecializedTemplate()),
5310  QualLoc, RecLoc.getNameLoc());
5311 
5312  return TemplateArgumentLoc();
5313 }
5314 
5315 /// Check that the given template argument corresponds to the given
5316 /// template parameter.
5317 ///
5318 /// \param Param The template parameter against which the argument will be
5319 /// checked.
5320 ///
5321 /// \param Arg The template argument, which may be updated due to conversions.
5322 ///
5323 /// \param Template The template in which the template argument resides.
5324 ///
5325 /// \param TemplateLoc The location of the template name for the template
5326 /// whose argument list we're matching.
5327 ///
5328 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
5329 /// the template argument list.
5330 ///
5331 /// \param ArgumentPackIndex The index into the argument pack where this
5332 /// argument will be placed. Only valid if the parameter is a parameter pack.
5333 ///
5334 /// \param Converted The checked, converted argument will be added to the
5335 /// end of this small vector.
5336 ///
5337 /// \param CTAK Describes how we arrived at this particular template argument:
5338 /// explicitly written, deduced, etc.
5339 ///
5340 /// \returns true on error, false otherwise.
5342  TemplateArgumentLoc &Arg,
5343  NamedDecl *Template,
5344  SourceLocation TemplateLoc,
5345  SourceLocation RAngleLoc,
5346  unsigned ArgumentPackIndex,
5349  // Check template type parameters.
5350  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
5351  return CheckTemplateTypeArgument(TTP, Arg, Converted);
5352 
5353  // Check non-type template parameters.
5354  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5355  // Do substitution on the type of the non-type template parameter
5356  // with the template arguments we've seen thus far. But if the
5357  // template has a dependent context then we cannot substitute yet.
5358  QualType NTTPType = NTTP->getType();
5359  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
5360  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
5361 
5362  if (NTTPType->isInstantiationDependentType() &&
5363  !isa<TemplateTemplateParmDecl>(Template) &&
5364  !Template->getDeclContext()->isDependentContext()) {
5365  // Do substitution on the type of the non-type template parameter.
5366  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5367  NTTP, Converted,
5368  SourceRange(TemplateLoc, RAngleLoc));
5369  if (Inst.isInvalid())
5370  return true;
5371 
5373  Converted);
5374 
5375  // If the parameter is a pack expansion, expand this slice of the pack.
5376  if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
5377  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
5378  ArgumentPackIndex);
5379  NTTPType = SubstType(PET->getPattern(),
5380  MultiLevelTemplateArgumentList(TemplateArgs),
5381  NTTP->getLocation(),
5382  NTTP->getDeclName());
5383  } else {
5384  NTTPType = SubstType(NTTPType,
5385  MultiLevelTemplateArgumentList(TemplateArgs),
5386  NTTP->getLocation(),
5387  NTTP->getDeclName());
5388  }
5389 
5390  // If that worked, check the non-type template parameter type
5391  // for validity.
5392  if (!NTTPType.isNull())
5393  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
5394  NTTP->getLocation());
5395  if (NTTPType.isNull())
5396  return true;
5397  }
5398 
5399  switch (Arg.getArgument().getKind()) {
5401  llvm_unreachable("Should never see a NULL template argument here");
5402 
5404  TemplateArgument Result;
5405  unsigned CurSFINAEErrors = NumSFINAEErrors;
5406  ExprResult Res =
5407  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
5408  Result, CTAK);
5409  if (Res.isInvalid())
5410  return true;
5411  // If the current template argument causes an error, give up now.
5412  if (CurSFINAEErrors < NumSFINAEErrors)
5413  return true;
5414 
5415  // If the resulting expression is new, then use it in place of the
5416  // old expression in the template argument.
5417  if (Res.get() != Arg.getArgument().getAsExpr()) {
5418  TemplateArgument TA(Res.get());
5419  Arg = TemplateArgumentLoc(TA, Res.get());
5420  }
5421 
5422  Converted.push_back(Result);
5423  break;
5424  }
5425 
5429  // We've already checked this template argument, so just copy
5430  // it to the list of converted arguments.
5431  Converted.push_back(Arg.getArgument());
5432  break;
5433 
5436  // We were given a template template argument. It may not be ill-formed;
5437  // see below.
5438  if (DependentTemplateName *DTN
5441  // We have a template argument such as \c T::template X, which we
5442  // parsed as a template template argument. However, since we now
5443  // know that we need a non-type template argument, convert this
5444  // template name into an expression.
5445 
5446  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
5447  Arg.getTemplateNameLoc());
5448 
5449  CXXScopeSpec SS;
5450  SS.Adopt(Arg.getTemplateQualifierLoc());
5451  // FIXME: the template-template arg was a DependentTemplateName,
5452  // so it was provided with a template keyword. However, its source
5453  // location is not stored in the template argument structure.
5454  SourceLocation TemplateKWLoc;
5456  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
5457  nullptr);
5458 
5459  // If we parsed the template argument as a pack expansion, create a
5460  // pack expansion expression.
5462  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
5463  if (E.isInvalid())
5464  return true;
5465  }
5466 
5467  TemplateArgument Result;
5468  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
5469  if (E.isInvalid())
5470  return true;
5471 
5472  Converted.push_back(Result);
5473  break;
5474  }
5475 
5476  // We have a template argument that actually does refer to a class
5477  // template, alias template, or template template parameter, and
5478  // therefore cannot be a non-type template argument.
5479  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
5480  << Arg.getSourceRange();
5481 
5482  Diag(Param->getLocation(), diag::note_template_param_here);
5483  return true;
5484 
5485  case TemplateArgument::Type: {
5486  // We have a non-type template parameter but the template
5487  // argument is a type.
5488 
5489  // C++ [temp.arg]p2:
5490  // In a template-argument, an ambiguity between a type-id and
5491  // an expression is resolved to a type-id, regardless of the
5492  // form of the corresponding template-parameter.
5493  //
5494  // We warn specifically about this case, since it can be rather
5495  // confusing for users.
5496  QualType T = Arg.getArgument().getAsType();
5497  SourceRange SR = Arg.getSourceRange();
5498  if (T->isFunctionType())
5499  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
5500  else
5501  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
5502  Diag(Param->getLocation(), diag::note_template_param_here);
5503  return true;
5504  }
5505 
5507  llvm_unreachable("Caller must expand template argument packs");
5508  }
5509 
5510  return false;
5511  }
5512 
5513 
5514  // Check template template parameters.
5515  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
5516 
5517  TemplateParameterList *Params = TempParm->getTemplateParameters();
5518  if (TempParm->isExpandedParameterPack())
5519  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
5520 
5521  // Substitute into the template parameter list of the template
5522  // template parameter, since previously-supplied template arguments
5523  // may appear within the template template parameter.
5524  //
5525  // FIXME: Skip this if the parameters aren't instantiation-dependent.
5526  {
5527  // Set up a template instantiation context.
5529  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5530  TempParm, Converted,
5531  SourceRange(TemplateLoc, RAngleLoc));
5532  if (Inst.isInvalid())
5533  return true;
5534 
5535  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5536  Params = SubstTemplateParams(Params, CurContext,
5537  MultiLevelTemplateArgumentList(TemplateArgs));
5538  if (!Params)
5539  return true;
5540  }
5541 
5542  // C++1z [temp.local]p1: (DR1004)
5543  // When [the injected-class-name] is used [...] as a template-argument for
5544  // a template template-parameter [...] it refers to the class template
5545  // itself.
5546  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
5548  Context, Arg.getTypeSourceInfo()->getTypeLoc());
5549  if (!ConvertedArg.getArgument().isNull())
5550  Arg = ConvertedArg;
5551  }
5552 
5553  switch (Arg.getArgument().getKind()) {
5555  llvm_unreachable("Should never see a NULL template argument here");
5556 
5559  if (CheckTemplateTemplateArgument(TempParm, Params, Arg))
5560  return true;
5561 
5562  Converted.push_back(Arg.getArgument());
5563  break;
5564 
5567  // We have a template template parameter but the template
5568  // argument does not refer to a template.
5569  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
5570  << getLangOpts().CPlusPlus11;
5571  return true;
5572 
5574  llvm_unreachable("Declaration argument with template template parameter");
5576  llvm_unreachable("Integral argument with template template parameter");
5578  llvm_unreachable("Null pointer argument with template template parameter");
5579 
5581  llvm_unreachable("Caller must expand template argument packs");
5582  }
5583 
5584  return false;
5585 }
5586 
5587 /// Diagnose a missing template argument.
5588 template<typename TemplateParmDecl>
5590  TemplateDecl *TD,
5591  const TemplateParmDecl *D,
5592  TemplateArgumentListInfo &Args) {
5593  // Dig out the most recent declaration of the template parameter; there may be
5594  // declarations of the template that are more recent than TD.
5595  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
5596  ->getTemplateParameters()
5597  ->getParam(D->getIndex()));
5598 
5599  // If there's a default argument that's not visible, diagnose that we're
5600  // missing a module import.
5602  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5603  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5604  D->getDefaultArgumentLoc(), Modules,
5606  /*Recover*/true);
5607  return true;
5608  }
5609 
5610  // FIXME: If there's a more recent default argument that *is* visible,
5611  // diagnose that it was declared too late.
5612 
5614 
5615  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5616  << /*not enough args*/0
5618  << TD;
5619  S.Diag(TD->getLocation(), diag::note_template_decl_here)
5620  << Params->getSourceRange();
5621  return true;
5622 }
5623 
5624 /// Check that the given template argument list is well-formed
5625 /// for specializing the given template.
5627  TemplateDecl *Template, SourceLocation TemplateLoc,
5628  TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
5630  bool UpdateArgsWithConversions, bool *ConstraintsNotSatisfied) {
5631 
5632  if (ConstraintsNotSatisfied)
5633  *ConstraintsNotSatisfied = false;
5634 
5635  // Make a copy of the template arguments for processing. Only make the
5636  // changes at the end when successful in matching the arguments to the
5637  // template.
5638  TemplateArgumentListInfo NewArgs = TemplateArgs;
5639 
5640  // Make sure we get the template parameter list from the most
5641  // recentdeclaration, since that is the o