clang  14.0.0git
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(DefaultTInfo)) {
1083  Param->setInvalidDecl();
1084  return Param;
1085  }
1086 
1087  Param->setDefaultArgument(DefaultTInfo);
1088  }
1089 
1090  return Param;
1091 }
1092 
1093 /// Convert the parser's template argument list representation into our form.
1096  TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
1097  TemplateId.RAngleLoc);
1098  ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
1099  TemplateId.NumArgs);
1100  S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
1101  return TemplateArgs;
1102 }
1103 
1105  TemplateIdAnnotation *TypeConstr,
1106  TemplateTypeParmDecl *ConstrainedParameter,
1107  SourceLocation EllipsisLoc) {
1108  return BuildTypeConstraint(SS, TypeConstr, ConstrainedParameter, EllipsisLoc,
1109  false);
1110 }
1111 
1113  TemplateIdAnnotation *TypeConstr,
1114  TemplateTypeParmDecl *ConstrainedParameter,
1115  SourceLocation EllipsisLoc,
1116  bool AllowUnexpandedPack) {
1117  TemplateName TN = TypeConstr->Template.get();
1118  ConceptDecl *CD = cast<ConceptDecl>(TN.getAsTemplateDecl());
1119 
1120  // C++2a [temp.param]p4:
1121  // [...] The concept designated by a type-constraint shall be a type
1122  // concept ([temp.concept]).
1123  if (!CD->isTypeConcept()) {
1124  Diag(TypeConstr->TemplateNameLoc,
1125  diag::err_type_constraint_non_type_concept);
1126  return true;
1127  }
1128 
1129  bool WereArgsSpecified = TypeConstr->LAngleLoc.isValid();
1130 
1131  if (!WereArgsSpecified &&
1133  Diag(TypeConstr->TemplateNameLoc,
1134  diag::err_type_constraint_missing_arguments) << CD;
1135  return true;
1136  }
1137 
1138  DeclarationNameInfo ConceptName(DeclarationName(TypeConstr->Name),
1139  TypeConstr->TemplateNameLoc);
1140 
1141  TemplateArgumentListInfo TemplateArgs;
1142  if (TypeConstr->LAngleLoc.isValid()) {
1143  TemplateArgs =
1144  makeTemplateArgumentListInfo(*this, *TypeConstr);
1145 
1146  if (EllipsisLoc.isInvalid() && !AllowUnexpandedPack) {
1147  for (TemplateArgumentLoc Arg : TemplateArgs.arguments()) {
1148  if (DiagnoseUnexpandedParameterPack(Arg, UPPC_TypeConstraint))
1149  return true;
1150  }
1151  }
1152  }
1153  return AttachTypeConstraint(
1154  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc(),
1155  ConceptName, CD,
1156  TypeConstr->LAngleLoc.isValid() ? &TemplateArgs : nullptr,
1157  ConstrainedParameter, EllipsisLoc);
1158 }
1159 
1160 template<typename ArgumentLocAppender>
1163  ConceptDecl *NamedConcept, SourceLocation LAngleLoc,
1164  SourceLocation RAngleLoc, QualType ConstrainedType,
1165  SourceLocation ParamNameLoc, ArgumentLocAppender Appender,
1166  SourceLocation EllipsisLoc) {
1167 
1168  TemplateArgumentListInfo ConstraintArgs;
1169  ConstraintArgs.addArgument(
1171  /*NTTPType=*/QualType(), ParamNameLoc));
1172 
1173  ConstraintArgs.setRAngleLoc(RAngleLoc);
1174  ConstraintArgs.setLAngleLoc(LAngleLoc);
1175  Appender(ConstraintArgs);
1176 
1177  // C++2a [temp.param]p4:
1178  // [...] This constraint-expression E is called the immediately-declared
1179  // constraint of T. [...]
1180  CXXScopeSpec SS;
1181  SS.Adopt(NS);
1182  ExprResult ImmediatelyDeclaredConstraint = S.CheckConceptTemplateId(
1183  SS, /*TemplateKWLoc=*/SourceLocation(), NameInfo,
1184  /*FoundDecl=*/NamedConcept, NamedConcept, &ConstraintArgs);
1185  if (ImmediatelyDeclaredConstraint.isInvalid() || !EllipsisLoc.isValid())
1186  return ImmediatelyDeclaredConstraint;
1187 
1188  // C++2a [temp.param]p4:
1189  // [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
1190  //
1191  // We have the following case:
1192  //
1193  // template<typename T> concept C1 = true;
1194  // template<C1... T> struct s1;
1195  //
1196  // The constraint: (C1<T> && ...)
1197  //
1198  // Note that the type of C1<T> is known to be 'bool', so we don't need to do
1199  // any unqualified lookups for 'operator&&' here.
1200  return S.BuildCXXFoldExpr(/*UnqualifiedLookup=*/nullptr,
1201  /*LParenLoc=*/SourceLocation(),
1202  ImmediatelyDeclaredConstraint.get(), BO_LAnd,
1203  EllipsisLoc, /*RHS=*/nullptr,
1204  /*RParenLoc=*/SourceLocation(),
1205  /*NumExpansions=*/None);
1206 }
1207 
1208 /// Attach a type-constraint to a template parameter.
1209 /// \returns true if an error occurred. This can happen if the
1210 /// immediately-declared constraint could not be formed (e.g. incorrect number
1211 /// of arguments for the named concept).
1213  DeclarationNameInfo NameInfo,
1214  ConceptDecl *NamedConcept,
1215  const TemplateArgumentListInfo *TemplateArgs,
1216  TemplateTypeParmDecl *ConstrainedParameter,
1217  SourceLocation EllipsisLoc) {
1218  // C++2a [temp.param]p4:
1219  // [...] If Q is of the form C<A1, ..., An>, then let E' be
1220  // C<T, A1, ..., An>. Otherwise, let E' be C<T>. [...]
1221  const ASTTemplateArgumentListInfo *ArgsAsWritten =
1222  TemplateArgs ? ASTTemplateArgumentListInfo::Create(Context,
1223  *TemplateArgs) : nullptr;
1224 
1225  QualType ParamAsArgument(ConstrainedParameter->getTypeForDecl(), 0);
1226 
1227  ExprResult ImmediatelyDeclaredConstraint =
1229  *this, NS, NameInfo, NamedConcept,
1230  TemplateArgs ? TemplateArgs->getLAngleLoc() : SourceLocation(),
1231  TemplateArgs ? TemplateArgs->getRAngleLoc() : SourceLocation(),
1232  ParamAsArgument, ConstrainedParameter->getLocation(),
1233  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1234  if (TemplateArgs)
1235  for (const auto &ArgLoc : TemplateArgs->arguments())
1236  ConstraintArgs.addArgument(ArgLoc);
1237  }, EllipsisLoc);
1238  if (ImmediatelyDeclaredConstraint.isInvalid())
1239  return true;
1240 
1241  ConstrainedParameter->setTypeConstraint(NS, NameInfo,
1242  /*FoundDecl=*/NamedConcept,
1243  NamedConcept, ArgsAsWritten,
1244  ImmediatelyDeclaredConstraint.get());
1245  return false;
1246 }
1247 
1249  SourceLocation EllipsisLoc) {
1250  if (NTTP->getType() != TL.getType() ||
1253  diag::err_unsupported_placeholder_constraint)
1255  return true;
1256  }
1257  // FIXME: Concepts: This should be the type of the placeholder, but this is
1258  // unclear in the wording right now.
1259  DeclRefExpr *Ref =
1260  BuildDeclRefExpr(NTTP, NTTP->getType(), VK_PRValue, NTTP->getLocation());
1261  if (!Ref)
1262  return true;
1263  ExprResult ImmediatelyDeclaredConstraint =
1266  TL.getNamedConcept(), TL.getLAngleLoc(), TL.getRAngleLoc(),
1267  BuildDecltypeType(Ref, NTTP->getLocation()), NTTP->getLocation(),
1268  [&] (TemplateArgumentListInfo &ConstraintArgs) {
1269  for (unsigned I = 0, C = TL.getNumArgs(); I != C; ++I)
1270  ConstraintArgs.addArgument(TL.getArgLoc(I));
1271  }, EllipsisLoc);
1272  if (ImmediatelyDeclaredConstraint.isInvalid() ||
1273  !ImmediatelyDeclaredConstraint.isUsable())
1274  return true;
1275 
1276  NTTP->setPlaceholderTypeConstraint(ImmediatelyDeclaredConstraint.get());
1277  return false;
1278 }
1279 
1280 /// Check that the type of a non-type template parameter is
1281 /// well-formed.
1282 ///
1283 /// \returns the (possibly-promoted) parameter type if valid;
1284 /// otherwise, produces a diagnostic and returns a NULL type.
1286  SourceLocation Loc) {
1287  if (TSI->getType()->isUndeducedType()) {
1288  // C++17 [temp.dep.expr]p3:
1289  // An id-expression is type-dependent if it contains
1290  // - an identifier associated by name lookup with a non-type
1291  // template-parameter declared with a type that contains a
1292  // placeholder type (7.1.7.4),
1293  TSI = SubstAutoTypeSourceInfo(TSI, Context.DependentTy);
1294  }
1295 
1296  return CheckNonTypeTemplateParameterType(TSI->getType(), Loc);
1297 }
1298 
1299 /// Require the given type to be a structural type, and diagnose if it is not.
1300 ///
1301 /// \return \c true if an error was produced.
1303  if (T->isDependentType())
1304  return false;
1305 
1306  if (RequireCompleteType(Loc, T, diag::err_template_nontype_parm_incomplete))
1307  return true;
1308 
1309  if (T->isStructuralType())
1310  return false;
1311 
1312  // Structural types are required to be object types or lvalue references.
1313  if (T->isRValueReferenceType()) {
1314  Diag(Loc, diag::err_template_nontype_parm_rvalue_ref) << T;
1315  return true;
1316  }
1317 
1318  // Don't mention structural types in our diagnostic prior to C++20. Also,
1319  // there's not much more we can say about non-scalar non-class types --
1320  // because we can't see functions or arrays here, those can only be language
1321  // extensions.
1322  if (!getLangOpts().CPlusPlus20 ||
1323  (!T->isScalarType() && !T->isRecordType())) {
1324  Diag(Loc, diag::err_template_nontype_parm_bad_type) << T;
1325  return true;
1326  }
1327 
1328  // Structural types are required to be literal types.
1329  if (RequireLiteralType(Loc, T, diag::err_template_nontype_parm_not_literal))
1330  return true;
1331 
1332  Diag(Loc, diag::err_template_nontype_parm_not_structural) << T;
1333 
1334  // Drill down into the reason why the class is non-structural.
1335  while (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
1336  // All members are required to be public and non-mutable, and can't be of
1337  // rvalue reference type. Check these conditions first to prefer a "local"
1338  // reason over a more distant one.
1339  for (const FieldDecl *FD : RD->fields()) {
1340  if (FD->getAccess() != AS_public) {
1341  Diag(FD->getLocation(), diag::note_not_structural_non_public) << T << 0;
1342  return true;
1343  }
1344  if (FD->isMutable()) {
1345  Diag(FD->getLocation(), diag::note_not_structural_mutable_field) << T;
1346  return true;
1347  }
1348  if (FD->getType()->isRValueReferenceType()) {
1349  Diag(FD->getLocation(), diag::note_not_structural_rvalue_ref_field)
1350  << T;
1351  return true;
1352  }
1353  }
1354 
1355  // All bases are required to be public.
1356  for (const auto &BaseSpec : RD->bases()) {
1357  if (BaseSpec.getAccessSpecifier() != AS_public) {
1358  Diag(BaseSpec.getBaseTypeLoc(), diag::note_not_structural_non_public)
1359  << T << 1;
1360  return true;
1361  }
1362  }
1363 
1364  // All subobjects are required to be of structural types.
1365  SourceLocation SubLoc;
1366  QualType SubType;
1367  int Kind = -1;
1368 
1369  for (const FieldDecl *FD : RD->fields()) {
1370  QualType T = Context.getBaseElementType(FD->getType());
1371  if (!T->isStructuralType()) {
1372  SubLoc = FD->getLocation();
1373  SubType = T;
1374  Kind = 0;
1375  break;
1376  }
1377  }
1378 
1379  if (Kind == -1) {
1380  for (const auto &BaseSpec : RD->bases()) {
1381  QualType T = BaseSpec.getType();
1382  if (!T->isStructuralType()) {
1383  SubLoc = BaseSpec.getBaseTypeLoc();
1384  SubType = T;
1385  Kind = 1;
1386  break;
1387  }
1388  }
1389  }
1390 
1391  assert(Kind != -1 && "couldn't find reason why type is not structural");
1392  Diag(SubLoc, diag::note_not_structural_subobject)
1393  << T << Kind << SubType;
1394  T = SubType;
1395  RD = T->getAsCXXRecordDecl();
1396  }
1397 
1398  return true;
1399 }
1400 
1402  SourceLocation Loc) {
1403  // We don't allow variably-modified types as the type of non-type template
1404  // parameters.
1405  if (T->isVariablyModifiedType()) {
1406  Diag(Loc, diag::err_variably_modified_nontype_template_param)
1407  << T;
1408  return QualType();
1409  }
1410 
1411  // C++ [temp.param]p4:
1412  //
1413  // A non-type template-parameter shall have one of the following
1414  // (optionally cv-qualified) types:
1415  //
1416  // -- integral or enumeration type,
1417  if (T->isIntegralOrEnumerationType() ||
1418  // -- pointer to object or pointer to function,
1419  T->isPointerType() ||
1420  // -- lvalue reference to object or lvalue reference to function,
1421  T->isLValueReferenceType() ||
1422  // -- pointer to member,
1423  T->isMemberPointerType() ||
1424  // -- std::nullptr_t, or
1425  T->isNullPtrType() ||
1426  // -- a type that contains a placeholder type.
1427  T->isUndeducedType()) {
1428  // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
1429  // are ignored when determining its type.
1430  return T.getUnqualifiedType();
1431  }
1432 
1433  // C++ [temp.param]p8:
1434  //
1435  // A non-type template-parameter of type "array of T" or
1436  // "function returning T" is adjusted to be of type "pointer to
1437  // T" or "pointer to function returning T", respectively.
1438  if (T->isArrayType() || T->isFunctionType())
1439  return Context.getDecayedType(T);
1440 
1441  // If T is a dependent type, we can't do the check now, so we
1442  // assume that it is well-formed. Note that stripping off the
1443  // qualifiers here is not really correct if T turns out to be
1444  // an array type, but we'll recompute the type everywhere it's
1445  // used during instantiation, so that should be OK. (Using the
1446  // qualified type is equally wrong.)
1447  if (T->isDependentType())
1448  return T.getUnqualifiedType();
1449 
1450  // C++20 [temp.param]p6:
1451  // -- a structural type
1452  if (RequireStructuralType(T, Loc))
1453  return QualType();
1454 
1455  if (!getLangOpts().CPlusPlus20) {
1456  // FIXME: Consider allowing structural types as an extension in C++17. (In
1457  // earlier language modes, the template argument evaluation rules are too
1458  // inflexible.)
1459  Diag(Loc, diag::err_template_nontype_parm_bad_structural_type) << T;
1460  return QualType();
1461  }
1462 
1463  Diag(Loc, diag::warn_cxx17_compat_template_nontype_parm_type) << T;
1464  return T.getUnqualifiedType();
1465 }
1466 
1468  unsigned Depth,
1469  unsigned Position,
1470  SourceLocation EqualLoc,
1471  Expr *Default) {
1472  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
1473 
1474  // Check that we have valid decl-specifiers specified.
1475  auto CheckValidDeclSpecifiers = [this, &D] {
1476  // C++ [temp.param]
1477  // p1
1478  // template-parameter:
1479  // ...
1480  // parameter-declaration
1481  // p2
1482  // ... A storage class shall not be specified in a template-parameter
1483  // declaration.
1484  // [dcl.typedef]p1:
1485  // The typedef specifier [...] shall not be used in the decl-specifier-seq
1486  // of a parameter-declaration
1487  const DeclSpec &DS = D.getDeclSpec();
1488  auto EmitDiag = [this](SourceLocation Loc) {
1489  Diag(Loc, diag::err_invalid_decl_specifier_in_nontype_parm)
1490  << FixItHint::CreateRemoval(Loc);
1491  };
1493  EmitDiag(DS.getStorageClassSpecLoc());
1494 
1496  EmitDiag(DS.getThreadStorageClassSpecLoc());
1497 
1498  // [dcl.inline]p1:
1499  // The inline specifier can be applied only to the declaration or
1500  // definition of a variable or function.
1501 
1502  if (DS.isInlineSpecified())
1503  EmitDiag(DS.getInlineSpecLoc());
1504 
1505  // [dcl.constexpr]p1:
1506  // The constexpr specifier shall be applied only to the definition of a
1507  // variable or variable template or the declaration of a function or
1508  // function template.
1509 
1510  if (DS.hasConstexprSpecifier())
1511  EmitDiag(DS.getConstexprSpecLoc());
1512 
1513  // [dcl.fct.spec]p1:
1514  // Function-specifiers can be used only in function declarations.
1515 
1516  if (DS.isVirtualSpecified())
1517  EmitDiag(DS.getVirtualSpecLoc());
1518 
1519  if (DS.hasExplicitSpecifier())
1520  EmitDiag(DS.getExplicitSpecLoc());
1521 
1522  if (DS.isNoreturnSpecified())
1523  EmitDiag(DS.getNoreturnSpecLoc());
1524  };
1525 
1526  CheckValidDeclSpecifiers();
1527 
1528  if (TInfo->getType()->isUndeducedType()) {
1529  Diag(D.getIdentifierLoc(),
1530  diag::warn_cxx14_compat_template_nontype_parm_auto_type)
1531  << QualType(TInfo->getType()->getContainedAutoType(), 0);
1532  }
1533 
1534  assert(S->isTemplateParamScope() &&
1535  "Non-type template parameter not in template parameter scope!");
1536  bool Invalid = false;
1537 
1538  QualType T = CheckNonTypeTemplateParameterType(TInfo, D.getIdentifierLoc());
1539  if (T.isNull()) {
1540  T = Context.IntTy; // Recover with an 'int' type.
1541  Invalid = true;
1542  }
1543 
1544  CheckFunctionOrTemplateParamDeclarator(S, D);
1545 
1546  IdentifierInfo *ParamName = D.getIdentifier();
1547  bool IsParameterPack = D.hasEllipsis();
1549  Context, Context.getTranslationUnitDecl(), D.getBeginLoc(),
1550  D.getIdentifierLoc(), Depth, Position, ParamName, T, IsParameterPack,
1551  TInfo);
1552  Param->setAccess(AS_public);
1553 
1554  if (AutoTypeLoc TL = TInfo->getTypeLoc().getContainedAutoTypeLoc())
1555  if (TL.isConstrained())
1556  if (AttachTypeConstraint(TL, Param, D.getEllipsisLoc()))
1557  Invalid = true;
1558 
1559  if (Invalid)
1560  Param->setInvalidDecl();
1561 
1562  if (Param->isParameterPack())
1563  if (auto *LSI = getEnclosingLambda())
1564  LSI->LocalPacks.push_back(Param);
1565 
1566  if (ParamName) {
1568  ParamName);
1569 
1570  // Add the template parameter into the current scope.
1571  S->AddDecl(Param);
1572  IdResolver.AddDecl(Param);
1573  }
1574 
1575  // C++0x [temp.param]p9:
1576  // A default template-argument may be specified for any kind of
1577  // template-parameter that is not a template parameter pack.
1578  if (Default && IsParameterPack) {
1579  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1580  Default = nullptr;
1581  }
1582 
1583  // Check the well-formedness of the default template argument, if provided.
1584  if (Default) {
1585  // Check for unexpanded parameter packs.
1586  if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
1587  return Param;
1588 
1589  TemplateArgument Converted;
1590  ExprResult DefaultRes =
1591  CheckTemplateArgument(Param, Param->getType(), Default, Converted);
1592  if (DefaultRes.isInvalid()) {
1593  Param->setInvalidDecl();
1594  return Param;
1595  }
1596  Default = DefaultRes.get();
1597 
1598  Param->setDefaultArgument(Default);
1599  }
1600 
1601  return Param;
1602 }
1603 
1604 /// ActOnTemplateTemplateParameter - Called when a C++ template template
1605 /// parameter (e.g. T in template <template <typename> class T> class array)
1606 /// has been parsed. S is the current scope.
1608  SourceLocation TmpLoc,
1609  TemplateParameterList *Params,
1610  SourceLocation EllipsisLoc,
1611  IdentifierInfo *Name,
1612  SourceLocation NameLoc,
1613  unsigned Depth,
1614  unsigned Position,
1615  SourceLocation EqualLoc,
1616  ParsedTemplateArgument Default) {
1617  assert(S->isTemplateParamScope() &&
1618  "Template template parameter not in template parameter scope!");
1619 
1620  // Construct the parameter object.
1621  bool IsParameterPack = EllipsisLoc.isValid();
1622  TemplateTemplateParmDecl *Param =
1624  NameLoc.isInvalid()? TmpLoc : NameLoc,
1625  Depth, Position, IsParameterPack,
1626  Name, Params);
1627  Param->setAccess(AS_public);
1628 
1629  if (Param->isParameterPack())
1630  if (auto *LSI = getEnclosingLambda())
1631  LSI->LocalPacks.push_back(Param);
1632 
1633  // If the template template parameter has a name, then link the identifier
1634  // into the scope and lookup mechanisms.
1635  if (Name) {
1636  maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
1637 
1638  S->AddDecl(Param);
1639  IdResolver.AddDecl(Param);
1640  }
1641 
1642  if (Params->size() == 0) {
1643  Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
1644  << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
1645  Param->setInvalidDecl();
1646  }
1647 
1648  // C++0x [temp.param]p9:
1649  // A default template-argument may be specified for any kind of
1650  // template-parameter that is not a template parameter pack.
1651  if (IsParameterPack && !Default.isInvalid()) {
1652  Diag(EqualLoc, diag::err_template_param_pack_default_arg);
1654  }
1655 
1656  if (!Default.isInvalid()) {
1657  // Check only that we have a template template argument. We don't want to
1658  // try to check well-formedness now, because our template template parameter
1659  // might have dependent types in its template parameters, which we wouldn't
1660  // be able to match now.
1661  //
1662  // If none of the template template parameter's template arguments mention
1663  // other template parameters, we could actually perform more checking here.
1664  // However, it isn't worth doing.
1666  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
1667  Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
1668  << DefaultArg.getSourceRange();
1669  return Param;
1670  }
1671 
1672  // Check for unexpanded parameter packs.
1673  if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
1674  DefaultArg.getArgument().getAsTemplate(),
1675  UPPC_DefaultArgument))
1676  return Param;
1677 
1678  Param->setDefaultArgument(Context, DefaultArg);
1679  }
1680 
1681  return Param;
1682 }
1683 
1684 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
1685 /// constrained by RequiresClause, that contains the template parameters in
1686 /// Params.
1689  SourceLocation ExportLoc,
1690  SourceLocation TemplateLoc,
1691  SourceLocation LAngleLoc,
1692  ArrayRef<NamedDecl *> Params,
1693  SourceLocation RAngleLoc,
1694  Expr *RequiresClause) {
1695  if (ExportLoc.isValid())
1696  Diag(ExportLoc, diag::warn_template_export_unsupported);
1697 
1698  for (NamedDecl *P : Params)
1699  warnOnReservedIdentifier(P);
1700 
1702  Context, TemplateLoc, LAngleLoc,
1703  llvm::makeArrayRef(Params.data(), Params.size()),
1704  RAngleLoc, RequiresClause);
1705 }
1706 
1708  const CXXScopeSpec &SS) {
1709  if (SS.isSet())
1711 }
1712 
1714  Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
1715  CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
1716  const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
1717  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
1718  SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
1719  TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
1720  assert(TemplateParams && TemplateParams->size() > 0 &&
1721  "No template parameters");
1722  assert(TUK != TUK_Reference && "Can only declare or define class templates");
1723  bool Invalid = false;
1724 
1725  // Check that we can declare a template here.
1726  if (CheckTemplateDeclScope(S, TemplateParams))
1727  return true;
1728 
1730  assert(Kind != TTK_Enum && "can't build template of enumerated type");
1731 
1732  // There is no such thing as an unnamed class template.
1733  if (!Name) {
1734  Diag(KWLoc, diag::err_template_unnamed_class);
1735  return true;
1736  }
1737 
1738  // Find any previous declaration with this name. For a friend with no
1739  // scope explicitly specified, we only look for tag declarations (per
1740  // C++11 [basic.lookup.elab]p2).
1741  DeclContext *SemanticContext;
1742  LookupResult Previous(*this, Name, NameLoc,
1743  (SS.isEmpty() && TUK == TUK_Friend)
1744  ? LookupTagName : LookupOrdinaryName,
1745  forRedeclarationInCurContext());
1746  if (SS.isNotEmpty() && !SS.isInvalid()) {
1747  SemanticContext = computeDeclContext(SS, true);
1748  if (!SemanticContext) {
1749  // FIXME: Horrible, horrible hack! We can't currently represent this
1750  // in the AST, and historically we have just ignored such friend
1751  // class templates, so don't complain here.
1752  Diag(NameLoc, TUK == TUK_Friend
1753  ? diag::warn_template_qualified_friend_ignored
1754  : diag::err_template_qualified_declarator_no_match)
1755  << SS.getScopeRep() << SS.getRange();
1756  return TUK != TUK_Friend;
1757  }
1758 
1759  if (RequireCompleteDeclContext(SS, SemanticContext))
1760  return true;
1761 
1762  // If we're adding a template to a dependent context, we may need to
1763  // rebuilding some of the types used within the template parameter list,
1764  // now that we know what the current instantiation is.
1765  if (SemanticContext->isDependentContext()) {
1766  ContextRAII SavedContext(*this, SemanticContext);
1767  if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
1768  Invalid = true;
1769  } else if (TUK != TUK_Friend && TUK != TUK_Reference)
1770  diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc, false);
1771 
1772  LookupQualifiedName(Previous, SemanticContext);
1773  } else {
1774  SemanticContext = CurContext;
1775 
1776  // C++14 [class.mem]p14:
1777  // If T is the name of a class, then each of the following shall have a
1778  // name different from T:
1779  // -- every member template of class T
1780  if (TUK != TUK_Friend &&
1781  DiagnoseClassNameShadow(SemanticContext,
1782  DeclarationNameInfo(Name, NameLoc)))
1783  return true;
1784 
1785  LookupName(Previous, S);
1786  }
1787 
1788  if (Previous.isAmbiguous())
1789  return true;
1790 
1791  NamedDecl *PrevDecl = nullptr;
1792  if (Previous.begin() != Previous.end())
1793  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1794 
1795  if (PrevDecl && PrevDecl->isTemplateParameter()) {
1796  // Maybe we will complain about the shadowed template parameter.
1797  DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
1798  // Just pretend that we didn't see the previous declaration.
1799  PrevDecl = nullptr;
1800  }
1801 
1802  // If there is a previous declaration with the same name, check
1803  // whether this is a valid redeclaration.
1804  ClassTemplateDecl *PrevClassTemplate =
1805  dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
1806 
1807  // We may have found the injected-class-name of a class template,
1808  // class template partial specialization, or class template specialization.
1809  // In these cases, grab the template that is being defined or specialized.
1810  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
1811  cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
1812  PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
1813  PrevClassTemplate
1814  = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
1815  if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
1816  PrevClassTemplate
1817  = cast<ClassTemplateSpecializationDecl>(PrevDecl)
1818  ->getSpecializedTemplate();
1819  }
1820  }
1821 
1822  if (TUK == TUK_Friend) {
1823  // C++ [namespace.memdef]p3:
1824  // [...] When looking for a prior declaration of a class or a function
1825  // declared as a friend, and when the name of the friend class or
1826  // function is neither a qualified name nor a template-id, scopes outside
1827  // the innermost enclosing namespace scope are not considered.
1828  if (!SS.isSet()) {
1829  DeclContext *OutermostContext = CurContext;
1830  while (!OutermostContext->isFileContext())
1831  OutermostContext = OutermostContext->getLookupParent();
1832 
1833  if (PrevDecl &&
1834  (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
1835  OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
1836  SemanticContext = PrevDecl->getDeclContext();
1837  } else {
1838  // Declarations in outer scopes don't matter. However, the outermost
1839  // context we computed is the semantic context for our new
1840  // declaration.
1841  PrevDecl = PrevClassTemplate = nullptr;
1842  SemanticContext = OutermostContext;
1843 
1844  // Check that the chosen semantic context doesn't already contain a
1845  // declaration of this name as a non-tag type.
1846  Previous.clear(LookupOrdinaryName);
1847  DeclContext *LookupContext = SemanticContext;
1848  while (LookupContext->isTransparentContext())
1849  LookupContext = LookupContext->getLookupParent();
1850  LookupQualifiedName(Previous, LookupContext);
1851 
1852  if (Previous.isAmbiguous())
1853  return true;
1854 
1855  if (Previous.begin() != Previous.end())
1856  PrevDecl = (*Previous.begin())->getUnderlyingDecl();
1857  }
1858  }
1859  } else if (PrevDecl &&
1860  !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
1861  S, SS.isValid()))
1862  PrevDecl = PrevClassTemplate = nullptr;
1863 
1864  if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1865  PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1866  if (SS.isEmpty() &&
1867  !(PrevClassTemplate &&
1868  PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1869  SemanticContext->getRedeclContext()))) {
1870  Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1871  Diag(Shadow->getTargetDecl()->getLocation(),
1872  diag::note_using_decl_target);
1873  Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl) << 0;
1874  // Recover by ignoring the old declaration.
1875  PrevDecl = PrevClassTemplate = nullptr;
1876  }
1877  }
1878 
1879  if (PrevClassTemplate) {
1880  // Ensure that the template parameter lists are compatible. Skip this check
1881  // for a friend in a dependent context: the template parameter list itself
1882  // could be dependent.
1883  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1884  !TemplateParameterListsAreEqual(TemplateParams,
1885  PrevClassTemplate->getTemplateParameters(),
1886  /*Complain=*/true,
1887  TPL_TemplateMatch))
1888  return true;
1889 
1890  // C++ [temp.class]p4:
1891  // In a redeclaration, partial specialization, explicit
1892  // specialization or explicit instantiation of a class template,
1893  // the class-key shall agree in kind with the original class
1894  // template declaration (7.1.5.3).
1895  RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1896  if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1897  TUK == TUK_Definition, KWLoc, Name)) {
1898  Diag(KWLoc, diag::err_use_with_wrong_tag)
1899  << Name
1900  << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1901  Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1902  Kind = PrevRecordDecl->getTagKind();
1903  }
1904 
1905  // Check for redefinition of this class template.
1906  if (TUK == TUK_Definition) {
1907  if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1908  // If we have a prior definition that is not visible, treat this as
1909  // simply making that previous definition visible.
1910  NamedDecl *Hidden = nullptr;
1911  if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1912  SkipBody->ShouldSkip = true;
1913  SkipBody->Previous = Def;
1914  auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1915  assert(Tmpl && "original definition of a class template is not a "
1916  "class template?");
1917  makeMergedDefinitionVisible(Hidden);
1918  makeMergedDefinitionVisible(Tmpl);
1919  } else {
1920  Diag(NameLoc, diag::err_redefinition) << Name;
1921  Diag(Def->getLocation(), diag::note_previous_definition);
1922  // FIXME: Would it make sense to try to "forget" the previous
1923  // definition, as part of error recovery?
1924  return true;
1925  }
1926  }
1927  }
1928  } else if (PrevDecl) {
1929  // C++ [temp]p5:
1930  // A class template shall not have the same name as any other
1931  // template, class, function, object, enumeration, enumerator,
1932  // namespace, or type in the same scope (3.3), except as specified
1933  // in (14.5.4).
1934  Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1935  Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1936  return true;
1937  }
1938 
1939  // Check the template parameter list of this declaration, possibly
1940  // merging in the template parameter list from the previous class
1941  // template declaration. Skip this check for a friend in a dependent
1942  // context, because the template parameter list might be dependent.
1943  if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1944  CheckTemplateParameterList(
1945  TemplateParams,
1946  PrevClassTemplate
1947  ? PrevClassTemplate->getMostRecentDecl()->getTemplateParameters()
1948  : nullptr,
1949  (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1950  SemanticContext->isDependentContext())
1951  ? TPC_ClassTemplateMember
1952  : TUK == TUK_Friend ? TPC_FriendClassTemplate : TPC_ClassTemplate,
1953  SkipBody))
1954  Invalid = true;
1955 
1956  if (SS.isSet()) {
1957  // If the name of the template was qualified, we must be defining the
1958  // template out-of-line.
1959  if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1960  Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1961  : diag::err_member_decl_does_not_match)
1962  << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1963  Invalid = true;
1964  }
1965  }
1966 
1967  // If this is a templated friend in a dependent context we should not put it
1968  // on the redecl chain. In some cases, the templated friend can be the most
1969  // recent declaration tricking the template instantiator to make substitutions
1970  // there.
1971  // FIXME: Figure out how to combine with shouldLinkDependentDeclWithPrevious
1972  bool ShouldAddRedecl
1973  = !(TUK == TUK_Friend && CurContext->isDependentContext());
1974 
1975  CXXRecordDecl *NewClass =
1976  CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1977  PrevClassTemplate && ShouldAddRedecl ?
1978  PrevClassTemplate->getTemplatedDecl() : nullptr,
1979  /*DelayTypeCreation=*/true);
1980  SetNestedNameSpecifier(*this, NewClass, SS);
1981  if (NumOuterTemplateParamLists > 0)
1983  Context, llvm::makeArrayRef(OuterTemplateParamLists,
1984  NumOuterTemplateParamLists));
1985 
1986  // Add alignment attributes if necessary; these attributes are checked when
1987  // the ASTContext lays out the structure.
1988  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
1989  AddAlignmentAttributesForRecord(NewClass);
1990  AddMsStructLayoutForRecord(NewClass);
1991  }
1992 
1993  ClassTemplateDecl *NewTemplate
1994  = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1995  DeclarationName(Name), TemplateParams,
1996  NewClass);
1997 
1998  if (ShouldAddRedecl)
1999  NewTemplate->setPreviousDecl(PrevClassTemplate);
2000 
2001  NewClass->setDescribedClassTemplate(NewTemplate);
2002 
2003  if (ModulePrivateLoc.isValid())
2004  NewTemplate->setModulePrivate();
2005 
2006  // Build the type for the class template declaration now.
2007  QualType T = NewTemplate->getInjectedClassNameSpecialization();
2008  T = Context.getInjectedClassNameType(NewClass, T);
2009  assert(T->isDependentType() && "Class template type is not dependent?");
2010  (void)T;
2011 
2012  // If we are providing an explicit specialization of a member that is a
2013  // class template, make a note of that.
2014  if (PrevClassTemplate &&
2015  PrevClassTemplate->getInstantiatedFromMemberTemplate())
2016  PrevClassTemplate->setMemberSpecialization();
2017 
2018  // Set the access specifier.
2019  if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
2020  SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
2021 
2022  // Set the lexical context of these templates
2023  NewClass->setLexicalDeclContext(CurContext);
2024  NewTemplate->setLexicalDeclContext(CurContext);
2025 
2026  if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
2027  NewClass->startDefinition();
2028 
2029  ProcessDeclAttributeList(S, NewClass, Attr);
2030 
2031  if (PrevClassTemplate)
2032  mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
2033 
2034  AddPushedVisibilityAttribute(NewClass);
2035  inferGslOwnerPointerAttribute(NewClass);
2036 
2037  if (TUK != TUK_Friend) {
2038  // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
2039  Scope *Outer = S;
2040  while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
2041  Outer = Outer->getParent();
2042  PushOnScopeChains(NewTemplate, Outer);
2043  } else {
2044  if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
2045  NewTemplate->setAccess(PrevClassTemplate->getAccess());
2046  NewClass->setAccess(PrevClassTemplate->getAccess());
2047  }
2048 
2049  NewTemplate->setObjectOfFriendDecl();
2050 
2051  // Friend templates are visible in fairly strange ways.
2052  if (!CurContext->isDependentContext()) {
2053  DeclContext *DC = SemanticContext->getRedeclContext();
2054  DC->makeDeclVisibleInContext(NewTemplate);
2055  if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
2056  PushOnScopeChains(NewTemplate, EnclosingScope,
2057  /* AddToContext = */ false);
2058  }
2059 
2060  FriendDecl *Friend = FriendDecl::Create(
2061  Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
2062  Friend->setAccess(AS_public);
2063  CurContext->addDecl(Friend);
2064  }
2065 
2066  if (PrevClassTemplate)
2067  CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
2068 
2069  if (Invalid) {
2070  NewTemplate->setInvalidDecl();
2071  NewClass->setInvalidDecl();
2072  }
2073 
2074  ActOnDocumentableDecl(NewTemplate);
2075 
2076  if (SkipBody && SkipBody->ShouldSkip)
2077  return SkipBody->Previous;
2078 
2079  return NewTemplate;
2080 }
2081 
2082 namespace {
2083 /// Tree transform to "extract" a transformed type from a class template's
2084 /// constructor to a deduction guide.
2085 class ExtractTypeForDeductionGuide
2086  : public TreeTransform<ExtractTypeForDeductionGuide> {
2087  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs;
2088 
2089 public:
2091  ExtractTypeForDeductionGuide(
2092  Sema &SemaRef,
2093  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs)
2094  : Base(SemaRef), MaterializedTypedefs(MaterializedTypedefs) {}
2095 
2096  TypeSourceInfo *transform(TypeSourceInfo *TSI) { return TransformType(TSI); }
2097 
2098  QualType TransformTypedefType(TypeLocBuilder &TLB, TypedefTypeLoc TL) {
2099  ASTContext &Context = SemaRef.getASTContext();
2100  TypedefNameDecl *OrigDecl = TL.getTypedefNameDecl();
2101  TypedefNameDecl *Decl = OrigDecl;
2102  // Transform the underlying type of the typedef and clone the Decl only if
2103  // the typedef has a dependent context.
2104  if (OrigDecl->getDeclContext()->isDependentContext()) {
2105  TypeLocBuilder InnerTLB;
2106  QualType Transformed =
2107  TransformType(InnerTLB, OrigDecl->getTypeSourceInfo()->getTypeLoc());
2108  TypeSourceInfo *TSI = InnerTLB.getTypeSourceInfo(Context, Transformed);
2109  if (isa<TypeAliasDecl>(OrigDecl))
2111  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2112  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2113  else {
2114  assert(isa<TypedefDecl>(OrigDecl) && "Not a Type alias or typedef");
2116  Context, Context.getTranslationUnitDecl(), OrigDecl->getBeginLoc(),
2117  OrigDecl->getLocation(), OrigDecl->getIdentifier(), TSI);
2118  }
2119  MaterializedTypedefs.push_back(Decl);
2120  }
2121 
2122  QualType TDTy = Context.getTypedefType(Decl);
2123  TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(TDTy);
2124  TypedefTL.setNameLoc(TL.getNameLoc());
2125 
2126  return TDTy;
2127  }
2128 };
2129 
2130 /// Transform to convert portions of a constructor declaration into the
2131 /// corresponding deduction guide, per C++1z [over.match.class.deduct]p1.
2132 struct ConvertConstructorToDeductionGuideTransform {
2133  ConvertConstructorToDeductionGuideTransform(Sema &S,
2134  ClassTemplateDecl *Template)
2135  : SemaRef(S), Template(Template) {}
2136 
2137  Sema &SemaRef;
2138  ClassTemplateDecl *Template;
2139 
2140  DeclContext *DC = Template->getDeclContext();
2141  CXXRecordDecl *Primary = Template->getTemplatedDecl();
2142  DeclarationName DeductionGuideName =
2144 
2145  QualType DeducedType = SemaRef.Context.getTypeDeclType(Primary);
2146 
2147  // Index adjustment to apply to convert depth-1 template parameters into
2148  // depth-0 template parameters.
2149  unsigned Depth1IndexAdjustment = Template->getTemplateParameters()->size();
2150 
2151  /// Transform a constructor declaration into a deduction guide.
2152  NamedDecl *transformConstructor(FunctionTemplateDecl *FTD,
2153  CXXConstructorDecl *CD) {
2155 
2156  LocalInstantiationScope Scope(SemaRef);
2157 
2158  // C++ [over.match.class.deduct]p1:
2159  // -- For each constructor of the class template designated by the
2160  // template-name, a function template with the following properties:
2161 
2162  // -- The template parameters are the template parameters of the class
2163  // template followed by the template parameters (including default
2164  // template arguments) of the constructor, if any.
2165  TemplateParameterList *TemplateParams = Template->getTemplateParameters();
2166  if (FTD) {
2167  TemplateParameterList *InnerParams = FTD->getTemplateParameters();
2168  SmallVector<NamedDecl *, 16> AllParams;
2169  AllParams.reserve(TemplateParams->size() + InnerParams->size());
2170  AllParams.insert(AllParams.begin(),
2171  TemplateParams->begin(), TemplateParams->end());
2172  SubstArgs.reserve(InnerParams->size());
2173 
2174  // Later template parameters could refer to earlier ones, so build up
2175  // a list of substituted template arguments as we go.
2176  for (NamedDecl *Param : *InnerParams) {
2179  Args.addOuterTemplateArguments(SubstArgs);
2180  Args.addOuterRetainedLevel();
2181  NamedDecl *NewParam = transformTemplateParameter(Param, Args);
2182  if (!NewParam)
2183  return nullptr;
2184  AllParams.push_back(NewParam);
2185  SubstArgs.push_back(SemaRef.Context.getCanonicalTemplateArgument(
2186  SemaRef.Context.getInjectedTemplateArg(NewParam)));
2187  }
2188  TemplateParams = TemplateParameterList::Create(
2189  SemaRef.Context, InnerParams->getTemplateLoc(),
2190  InnerParams->getLAngleLoc(), AllParams, InnerParams->getRAngleLoc(),
2191  /*FIXME: RequiresClause*/ nullptr);
2192  }
2193 
2194  // If we built a new template-parameter-list, track that we need to
2195  // substitute references to the old parameters into references to the
2196  // new ones.
2199  if (FTD) {
2200  Args.addOuterTemplateArguments(SubstArgs);
2201  Args.addOuterRetainedLevel();
2202  }
2203 
2206  assert(FPTL && "no prototype for constructor declaration");
2207 
2208  // Transform the type of the function, adjusting the return type and
2209  // replacing references to the old parameters with references to the
2210  // new ones.
2211  TypeLocBuilder TLB;
2213  SmallVector<TypedefNameDecl *, 4> MaterializedTypedefs;
2214  QualType NewType = transformFunctionProtoType(TLB, FPTL, Params, Args,
2215  MaterializedTypedefs);
2216  if (NewType.isNull())
2217  return nullptr;
2218  TypeSourceInfo *NewTInfo = TLB.getTypeSourceInfo(SemaRef.Context, NewType);
2219 
2220  return buildDeductionGuide(TemplateParams, CD, CD->getExplicitSpecifier(),
2221  NewTInfo, CD->getBeginLoc(), CD->getLocation(),
2222  CD->getEndLoc(), MaterializedTypedefs);
2223  }
2224 
2225  /// Build a deduction guide with the specified parameter types.
2226  NamedDecl *buildSimpleDeductionGuide(MutableArrayRef<QualType> ParamTypes) {
2227  SourceLocation Loc = Template->getLocation();
2228 
2229  // Build the requested type.
2231  EPI.HasTrailingReturn = true;
2232  QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
2233  DeductionGuideName, EPI);
2234  TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
2235 
2236  FunctionProtoTypeLoc FPTL =
2238 
2239  // Build the parameters, needed during deduction / substitution.
2241  for (auto T : ParamTypes) {
2242  ParmVarDecl *NewParam = ParmVarDecl::Create(
2243  SemaRef.Context, DC, Loc, Loc, nullptr, T,
2244  SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
2245  NewParam->setScopeInfo(0, Params.size());
2246  FPTL.setParam(Params.size(), NewParam);
2247  Params.push_back(NewParam);
2248  }
2249 
2250  return buildDeductionGuide(Template->getTemplateParameters(), nullptr,
2251  ExplicitSpecifier(), TSI, Loc, Loc, Loc);
2252  }
2253 
2254 private:
2255  /// Transform a constructor template parameter into a deduction guide template
2256  /// parameter, rebuilding any internal references to earlier parameters and
2257  /// renumbering as we go.
2258  NamedDecl *transformTemplateParameter(NamedDecl *TemplateParam,
2260  if (auto *TTP = dyn_cast<TemplateTypeParmDecl>(TemplateParam)) {
2261  // TemplateTypeParmDecl's index cannot be changed after creation, so
2262  // substitute it directly.
2263  auto *NewTTP = TemplateTypeParmDecl::Create(
2264  SemaRef.Context, DC, TTP->getBeginLoc(), TTP->getLocation(),
2265  /*Depth*/ 0, Depth1IndexAdjustment + TTP->getIndex(),
2266  TTP->getIdentifier(), TTP->wasDeclaredWithTypename(),
2267  TTP->isParameterPack(), TTP->hasTypeConstraint(),
2268  TTP->isExpandedParameterPack() ?
2269  llvm::Optional<unsigned>(TTP->getNumExpansionParameters()) : None);
2270  if (const auto *TC = TTP->getTypeConstraint())
2271  SemaRef.SubstTypeConstraint(NewTTP, TC, Args);
2272  if (TTP->hasDefaultArgument()) {
2273  TypeSourceInfo *InstantiatedDefaultArg =
2274  SemaRef.SubstType(TTP->getDefaultArgumentInfo(), Args,
2275  TTP->getDefaultArgumentLoc(), TTP->getDeclName());
2276  if (InstantiatedDefaultArg)
2277  NewTTP->setDefaultArgument(InstantiatedDefaultArg);
2278  }
2279  SemaRef.CurrentInstantiationScope->InstantiatedLocal(TemplateParam,
2280  NewTTP);
2281  return NewTTP;
2282  }
2283 
2284  if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(TemplateParam))
2285  return transformTemplateParameterImpl(TTP, Args);
2286 
2287  return transformTemplateParameterImpl(
2288  cast<NonTypeTemplateParmDecl>(TemplateParam), Args);
2289  }
2290  template<typename TemplateParmDecl>
2291  TemplateParmDecl *
2292  transformTemplateParameterImpl(TemplateParmDecl *OldParam,
2294  // Ask the template instantiator to do the heavy lifting for us, then adjust
2295  // the index of the parameter once it's done.
2296  auto *NewParam =
2297  cast<TemplateParmDecl>(SemaRef.SubstDecl(OldParam, DC, Args));
2298  assert(NewParam->getDepth() == 0 && "unexpected template param depth");
2299  NewParam->setPosition(NewParam->getPosition() + Depth1IndexAdjustment);
2300  return NewParam;
2301  }
2302 
2303  QualType transformFunctionProtoType(
2307  SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2308  SmallVector<QualType, 4> ParamTypes;
2309  const FunctionProtoType *T = TL.getTypePtr();
2310 
2311  // -- The types of the function parameters are those of the constructor.
2312  for (auto *OldParam : TL.getParams()) {
2313  ParmVarDecl *NewParam =
2314  transformFunctionTypeParam(OldParam, Args, MaterializedTypedefs);
2315  if (!NewParam)
2316  return QualType();
2317  ParamTypes.push_back(NewParam->getType());
2318  Params.push_back(NewParam);
2319  }
2320 
2321  // -- The return type is the class template specialization designated by
2322  // the template-name and template arguments corresponding to the
2323  // template parameters obtained from the class template.
2324  //
2325  // We use the injected-class-name type of the primary template instead.
2326  // This has the convenient property that it is different from any type that
2327  // the user can write in a deduction-guide (because they cannot enter the
2328  // context of the template), so implicit deduction guides can never collide
2329  // with explicit ones.
2330  QualType ReturnType = DeducedType;
2331  TLB.pushTypeSpec(ReturnType).setNameLoc(Primary->getLocation());
2332 
2333  // Resolving a wording defect, we also inherit the variadicness of the
2334  // constructor.
2336  EPI.Variadic = T->isVariadic();
2337  EPI.HasTrailingReturn = true;
2338 
2339  QualType Result = SemaRef.BuildFunctionType(
2340  ReturnType, ParamTypes, TL.getBeginLoc(), DeductionGuideName, EPI);
2341  if (Result.isNull())
2342  return QualType();
2343 
2344  FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
2346  NewTL.setLParenLoc(TL.getLParenLoc());
2347  NewTL.setRParenLoc(TL.getRParenLoc());
2349  NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
2350  for (unsigned I = 0, E = NewTL.getNumParams(); I != E; ++I)
2351  NewTL.setParam(I, Params[I]);
2352 
2353  return Result;
2354  }
2355 
2356  ParmVarDecl *transformFunctionTypeParam(
2358  llvm::SmallVectorImpl<TypedefNameDecl *> &MaterializedTypedefs) {
2359  TypeSourceInfo *OldDI = OldParam->getTypeSourceInfo();
2360  TypeSourceInfo *NewDI;
2361  if (auto PackTL = OldDI->getTypeLoc().getAs<PackExpansionTypeLoc>()) {
2362  // Expand out the one and only element in each inner pack.
2363  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, 0);
2364  NewDI =
2365  SemaRef.SubstType(PackTL.getPatternLoc(), Args,
2366  OldParam->getLocation(), OldParam->getDeclName());
2367  if (!NewDI) return nullptr;
2368  NewDI =
2369  SemaRef.CheckPackExpansion(NewDI, PackTL.getEllipsisLoc(),
2370  PackTL.getTypePtr()->getNumExpansions());
2371  } else
2372  NewDI = SemaRef.SubstType(OldDI, Args, OldParam->getLocation(),
2373  OldParam->getDeclName());
2374  if (!NewDI)
2375  return nullptr;
2376 
2377  // Extract the type. This (for instance) replaces references to typedef
2378  // members of the current instantiations with the definitions of those
2379  // typedefs, avoiding triggering instantiation of the deduced type during
2380  // deduction.
2381  NewDI = ExtractTypeForDeductionGuide(SemaRef, MaterializedTypedefs)
2382  .transform(NewDI);
2383 
2384  // Resolving a wording defect, we also inherit default arguments from the
2385  // constructor.
2386  ExprResult NewDefArg;
2387  if (OldParam->hasDefaultArg()) {
2388  // We don't care what the value is (we won't use it); just create a
2389  // placeholder to indicate there is a default argument.
2390  QualType ParamTy = NewDI->getType();
2391  NewDefArg = new (SemaRef.Context)
2392  OpaqueValueExpr(OldParam->getDefaultArg()->getBeginLoc(),
2393  ParamTy.getNonLValueExprType(SemaRef.Context),
2394  ParamTy->isLValueReferenceType() ? VK_LValue
2395  : ParamTy->isRValueReferenceType() ? VK_XValue
2396  : VK_PRValue);
2397  }
2398 
2399  ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,
2400  OldParam->getInnerLocStart(),
2401  OldParam->getLocation(),
2402  OldParam->getIdentifier(),
2403  NewDI->getType(),
2404  NewDI,
2405  OldParam->getStorageClass(),
2406  NewDefArg.get());
2407  NewParam->setScopeInfo(OldParam->getFunctionScopeDepth(),
2408  OldParam->getFunctionScopeIndex());
2409  SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldParam, NewParam);
2410  return NewParam;
2411  }
2412 
2413  FunctionTemplateDecl *buildDeductionGuide(
2414  TemplateParameterList *TemplateParams, CXXConstructorDecl *Ctor,
2415  ExplicitSpecifier ES, TypeSourceInfo *TInfo, SourceLocation LocStart,
2416  SourceLocation Loc, SourceLocation LocEnd,
2417  llvm::ArrayRef<TypedefNameDecl *> MaterializedTypedefs = {}) {
2418  DeclarationNameInfo Name(DeductionGuideName, Loc);
2419  ArrayRef<ParmVarDecl *> Params =
2420  TInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams();
2421 
2422  // Build the implicit deduction guide template.
2423  auto *Guide =
2424  CXXDeductionGuideDecl::Create(SemaRef.Context, DC, LocStart, ES, Name,
2425  TInfo->getType(), TInfo, LocEnd, Ctor);
2426  Guide->setImplicit();
2427  Guide->setParams(Params);
2428 
2429  for (auto *Param : Params)
2430  Param->setDeclContext(Guide);
2431  for (auto *TD : MaterializedTypedefs)
2432  TD->setDeclContext(Guide);
2433 
2434  auto *GuideTemplate = FunctionTemplateDecl::Create(
2435  SemaRef.Context, DC, Loc, DeductionGuideName, TemplateParams, Guide);
2436  GuideTemplate->setImplicit();
2437  Guide->setDescribedFunctionTemplate(GuideTemplate);
2438 
2439  if (isa<CXXRecordDecl>(DC)) {
2440  Guide->setAccess(AS_public);
2441  GuideTemplate->setAccess(AS_public);
2442  }
2443 
2444  DC->addDecl(GuideTemplate);
2445  return GuideTemplate;
2446  }
2447 };
2448 }
2449 
2451  SourceLocation Loc) {
2452  if (CXXRecordDecl *DefRecord =
2453  cast<CXXRecordDecl>(Template->getTemplatedDecl())->getDefinition()) {
2454  TemplateDecl *DescribedTemplate = DefRecord->getDescribedClassTemplate();
2455  Template = DescribedTemplate ? DescribedTemplate : Template;
2456  }
2457 
2458  DeclContext *DC = Template->getDeclContext();
2459  if (DC->isDependentContext())
2460  return;
2461 
2462  ConvertConstructorToDeductionGuideTransform Transform(
2463  *this, cast<ClassTemplateDecl>(Template));
2464  if (!isCompleteType(Loc, Transform.DeducedType))
2465  return;
2466 
2467  // Check whether we've already declared deduction guides for this template.
2468  // FIXME: Consider storing a flag on the template to indicate this.
2469  auto Existing = DC->lookup(Transform.DeductionGuideName);
2470  for (auto *D : Existing)
2471  if (D->isImplicit())
2472  return;
2473 
2474  // In case we were expanding a pack when we attempted to declare deduction
2475  // guides, turn off pack expansion for everything we're about to do.
2476  ArgumentPackSubstitutionIndexRAII SubstIndex(*this, -1);
2477  // Create a template instantiation record to track the "instantiation" of
2478  // constructors into deduction guides.
2479  // FIXME: Add a kind for this to give more meaningful diagnostics. But can
2480  // this substitution process actually fail?
2481  InstantiatingTemplate BuildingDeductionGuides(*this, Loc, Template);
2482  if (BuildingDeductionGuides.isInvalid())
2483  return;
2484 
2485  // Convert declared constructors into deduction guide templates.
2486  // FIXME: Skip constructors for which deduction must necessarily fail (those
2487  // for which some class template parameter without a default argument never
2488  // appears in a deduced context).
2489  bool AddedAny = false;
2490  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
2491  D = D->getUnderlyingDecl();
2492  if (D->isInvalidDecl() || D->isImplicit())
2493  continue;
2494  D = cast<NamedDecl>(D->getCanonicalDecl());
2495 
2496  auto *FTD = dyn_cast<FunctionTemplateDecl>(D);
2497  auto *CD =
2498  dyn_cast_or_null<CXXConstructorDecl>(FTD ? FTD->getTemplatedDecl() : D);
2499  // Class-scope explicit specializations (MS extension) do not result in
2500  // deduction guides.
2501  if (!CD || (!FTD && CD->isFunctionTemplateSpecialization()))
2502  continue;
2503 
2504  // Cannot make a deduction guide when unparsed arguments are present.
2505  if (std::any_of(CD->param_begin(), CD->param_end(), [](ParmVarDecl *P) {
2506  return !P || P->hasUnparsedDefaultArg();
2507  }))
2508  continue;
2509 
2510  Transform.transformConstructor(FTD, CD);
2511  AddedAny = true;
2512  }
2513 
2514  // C++17 [over.match.class.deduct]
2515  // -- If C is not defined or does not declare any constructors, an
2516  // additional function template derived as above from a hypothetical
2517  // constructor C().
2518  if (!AddedAny)
2519  Transform.buildSimpleDeductionGuide(None);
2520 
2521  // -- An additional function template derived as above from a hypothetical
2522  // constructor C(C), called the copy deduction candidate.
2523  cast<CXXDeductionGuideDecl>(
2524  cast<FunctionTemplateDecl>(
2525  Transform.buildSimpleDeductionGuide(Transform.DeducedType))
2526  ->getTemplatedDecl())
2527  ->setIsCopyDeductionCandidate();
2528 }
2529 
2530 /// Diagnose the presence of a default template argument on a
2531 /// template parameter, which is ill-formed in certain contexts.
2532 ///
2533 /// \returns true if the default template argument should be dropped.
2536  SourceLocation ParamLoc,
2537  SourceRange DefArgRange) {
2538  switch (TPC) {
2540  case Sema::TPC_VarTemplate:
2542  return false;
2543 
2546  // C++ [temp.param]p9:
2547  // A default template-argument shall not be specified in a
2548  // function template declaration or a function template
2549  // definition [...]
2550  // If a friend function template declaration specifies a default
2551  // template-argument, that declaration shall be a definition and shall be
2552  // the only declaration of the function template in the translation unit.
2553  // (C++98/03 doesn't have this wording; see DR226).
2554  S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
2555  diag::warn_cxx98_compat_template_parameter_default_in_function_template
2556  : diag::ext_template_parameter_default_in_function_template)
2557  << DefArgRange;
2558  return false;
2559 
2561  // C++0x [temp.param]p9:
2562  // A default template-argument shall not be specified in the
2563  // template-parameter-lists of the definition of a member of a
2564  // class template that appears outside of the member's class.
2565  S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
2566  << DefArgRange;
2567  return true;
2568 
2571  // C++ [temp.param]p9:
2572  // A default template-argument shall not be specified in a
2573  // friend template declaration.
2574  S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
2575  << DefArgRange;
2576  return true;
2577 
2578  // FIXME: C++0x [temp.param]p9 allows default template-arguments
2579  // for friend function templates if there is only a single
2580  // declaration (and it is a definition). Strange!
2581  }
2582 
2583  llvm_unreachable("Invalid TemplateParamListContext!");
2584 }
2585 
2586 /// Check for unexpanded parameter packs within the template parameters
2587 /// of a template template parameter, recursively.
2589  TemplateTemplateParmDecl *TTP) {
2590  // A template template parameter which is a parameter pack is also a pack
2591  // expansion.
2592  if (TTP->isParameterPack())
2593  return false;
2594 
2596  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
2597  NamedDecl *P = Params->getParam(I);
2598  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(P)) {
2599  if (!TTP->isParameterPack())
2600  if (const TypeConstraint *TC = TTP->getTypeConstraint())
2601  if (TC->hasExplicitTemplateArgs())
2602  for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
2603  if (S.DiagnoseUnexpandedParameterPack(ArgLoc,
2605  return true;
2606  continue;
2607  }
2608 
2609  if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
2610  if (!NTTP->isParameterPack() &&
2611  S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
2612  NTTP->getTypeSourceInfo(),
2614  return true;
2615 
2616  continue;
2617  }
2618 
2619  if (TemplateTemplateParmDecl *InnerTTP
2620  = dyn_cast<TemplateTemplateParmDecl>(P))
2621  if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
2622  return true;
2623  }
2624 
2625  return false;
2626 }
2627 
2628 /// Checks the validity of a template parameter list, possibly
2629 /// considering the template parameter list from a previous
2630 /// declaration.
2631 ///
2632 /// If an "old" template parameter list is provided, it must be
2633 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
2634 /// template parameter list.
2635 ///
2636 /// \param NewParams Template parameter list for a new template
2637 /// declaration. This template parameter list will be updated with any
2638 /// default arguments that are carried through from the previous
2639 /// template parameter list.
2640 ///
2641 /// \param OldParams If provided, template parameter list from a
2642 /// previous declaration of the same template. Default template
2643 /// arguments will be merged from the old template parameter list to
2644 /// the new template parameter list.
2645 ///
2646 /// \param TPC Describes the context in which we are checking the given
2647 /// template parameter list.
2648 ///
2649 /// \param SkipBody If we might have already made a prior merged definition
2650 /// of this template visible, the corresponding body-skipping information.
2651 /// Default argument redefinition is not an error when skipping such a body,
2652 /// because (under the ODR) we can assume the default arguments are the same
2653 /// as the prior merged definition.
2654 ///
2655 /// \returns true if an error occurred, false otherwise.
2657  TemplateParameterList *OldParams,
2659  SkipBodyInfo *SkipBody) {
2660  bool Invalid = false;
2661 
2662  // C++ [temp.param]p10:
2663  // The set of default template-arguments available for use with a
2664  // template declaration or definition is obtained by merging the
2665  // default arguments from the definition (if in scope) and all
2666  // declarations in scope in the same way default function
2667  // arguments are (8.3.6).
2668  bool SawDefaultArgument = false;
2669  SourceLocation PreviousDefaultArgLoc;
2670 
2671  // Dummy initialization to avoid warnings.
2672  TemplateParameterList::iterator OldParam = NewParams->end();
2673  if (OldParams)
2674  OldParam = OldParams->begin();
2675 
2676  bool RemoveDefaultArguments = false;
2677  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2678  NewParamEnd = NewParams->end();
2679  NewParam != NewParamEnd; ++NewParam) {
2680  // Variables used to diagnose redundant default arguments
2681  bool RedundantDefaultArg = false;
2682  SourceLocation OldDefaultLoc;
2683  SourceLocation NewDefaultLoc;
2684 
2685  // Variable used to diagnose missing default arguments
2686  bool MissingDefaultArg = false;
2687 
2688  // Variable used to diagnose non-final parameter packs
2689  bool SawParameterPack = false;
2690 
2691  if (TemplateTypeParmDecl *NewTypeParm
2692  = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
2693  // Check the presence of a default argument here.
2694  if (NewTypeParm->hasDefaultArgument() &&
2696  NewTypeParm->getLocation(),
2697  NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
2698  .getSourceRange()))
2699  NewTypeParm->removeDefaultArgument();
2700 
2701  // Merge default arguments for template type parameters.
2702  TemplateTypeParmDecl *OldTypeParm
2703  = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
2704  if (NewTypeParm->isParameterPack()) {
2705  assert(!NewTypeParm->hasDefaultArgument() &&
2706  "Parameter packs can't have a default argument!");
2707  SawParameterPack = true;
2708  } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
2709  NewTypeParm->hasDefaultArgument() &&
2710  (!SkipBody || !SkipBody->ShouldSkip)) {
2711  OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
2712  NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
2713  SawDefaultArgument = true;
2714  RedundantDefaultArg = true;
2715  PreviousDefaultArgLoc = NewDefaultLoc;
2716  } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
2717  // Merge the default argument from the old declaration to the
2718  // new declaration.
2719  NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
2720  PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
2721  } else if (NewTypeParm->hasDefaultArgument()) {
2722  SawDefaultArgument = true;
2723  PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
2724  } else if (SawDefaultArgument)
2725  MissingDefaultArg = true;
2726  } else if (NonTypeTemplateParmDecl *NewNonTypeParm
2727  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
2728  // Check for unexpanded parameter packs.
2729  if (!NewNonTypeParm->isParameterPack() &&
2730  DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
2731  NewNonTypeParm->getTypeSourceInfo(),
2732  UPPC_NonTypeTemplateParameterType)) {
2733  Invalid = true;
2734  continue;
2735  }
2736 
2737  // Check the presence of a default argument here.
2738  if (NewNonTypeParm->hasDefaultArgument() &&
2740  NewNonTypeParm->getLocation(),
2741  NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
2742  NewNonTypeParm->removeDefaultArgument();
2743  }
2744 
2745  // Merge default arguments for non-type template parameters
2746  NonTypeTemplateParmDecl *OldNonTypeParm
2747  = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
2748  if (NewNonTypeParm->isParameterPack()) {
2749  assert(!NewNonTypeParm->hasDefaultArgument() &&
2750  "Parameter packs can't have a default argument!");
2751  if (!NewNonTypeParm->isPackExpansion())
2752  SawParameterPack = true;
2753  } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
2754  NewNonTypeParm->hasDefaultArgument() &&
2755  (!SkipBody || !SkipBody->ShouldSkip)) {
2756  OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
2757  NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
2758  SawDefaultArgument = true;
2759  RedundantDefaultArg = true;
2760  PreviousDefaultArgLoc = NewDefaultLoc;
2761  } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
2762  // Merge the default argument from the old declaration to the
2763  // new declaration.
2764  NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
2765  PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
2766  } else if (NewNonTypeParm->hasDefaultArgument()) {
2767  SawDefaultArgument = true;
2768  PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
2769  } else if (SawDefaultArgument)
2770  MissingDefaultArg = true;
2771  } else {
2772  TemplateTemplateParmDecl *NewTemplateParm
2773  = cast<TemplateTemplateParmDecl>(*NewParam);
2774 
2775  // Check for unexpanded parameter packs, recursively.
2776  if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
2777  Invalid = true;
2778  continue;
2779  }
2780 
2781  // Check the presence of a default argument here.
2782  if (NewTemplateParm->hasDefaultArgument() &&
2784  NewTemplateParm->getLocation(),
2785  NewTemplateParm->getDefaultArgument().getSourceRange()))
2786  NewTemplateParm->removeDefaultArgument();
2787 
2788  // Merge default arguments for template template parameters
2789  TemplateTemplateParmDecl *OldTemplateParm
2790  = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
2791  if (NewTemplateParm->isParameterPack()) {
2792  assert(!NewTemplateParm->hasDefaultArgument() &&
2793  "Parameter packs can't have a default argument!");
2794  if (!NewTemplateParm->isPackExpansion())
2795  SawParameterPack = true;
2796  } else if (OldTemplateParm &&
2797  hasVisibleDefaultArgument(OldTemplateParm) &&
2798  NewTemplateParm->hasDefaultArgument() &&
2799  (!SkipBody || !SkipBody->ShouldSkip)) {
2800  OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
2801  NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
2802  SawDefaultArgument = true;
2803  RedundantDefaultArg = true;
2804  PreviousDefaultArgLoc = NewDefaultLoc;
2805  } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
2806  // Merge the default argument from the old declaration to the
2807  // new declaration.
2808  NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
2809  PreviousDefaultArgLoc
2810  = OldTemplateParm->getDefaultArgument().getLocation();
2811  } else if (NewTemplateParm->hasDefaultArgument()) {
2812  SawDefaultArgument = true;
2813  PreviousDefaultArgLoc
2814  = NewTemplateParm->getDefaultArgument().getLocation();
2815  } else if (SawDefaultArgument)
2816  MissingDefaultArg = true;
2817  }
2818 
2819  // C++11 [temp.param]p11:
2820  // If a template parameter of a primary class template or alias template
2821  // is a template parameter pack, it shall be the last template parameter.
2822  if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
2823  (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
2824  TPC == TPC_TypeAliasTemplate)) {
2825  Diag((*NewParam)->getLocation(),
2826  diag::err_template_param_pack_must_be_last_template_parameter);
2827  Invalid = true;
2828  }
2829 
2830  if (RedundantDefaultArg) {
2831  // C++ [temp.param]p12:
2832  // A template-parameter shall not be given default arguments
2833  // by two different declarations in the same scope.
2834  Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
2835  Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
2836  Invalid = true;
2837  } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
2838  // C++ [temp.param]p11:
2839  // If a template-parameter of a class template has a default
2840  // template-argument, each subsequent template-parameter shall either
2841  // have a default template-argument supplied or be a template parameter
2842  // pack.
2843  Diag((*NewParam)->getLocation(),
2844  diag::err_template_param_default_arg_missing);
2845  Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
2846  Invalid = true;
2847  RemoveDefaultArguments = true;
2848  }
2849 
2850  // If we have an old template parameter list that we're merging
2851  // in, move on to the next parameter.
2852  if (OldParams)
2853  ++OldParam;
2854  }
2855 
2856  // We were missing some default arguments at the end of the list, so remove
2857  // all of the default arguments.
2858  if (RemoveDefaultArguments) {
2859  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
2860  NewParamEnd = NewParams->end();
2861  NewParam != NewParamEnd; ++NewParam) {
2862  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
2863  TTP->removeDefaultArgument();
2864  else if (NonTypeTemplateParmDecl *NTTP
2865  = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
2866  NTTP->removeDefaultArgument();
2867  else
2868  cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
2869  }
2870  }
2871 
2872  return Invalid;
2873 }
2874 
2875 namespace {
2876 
2877 /// A class which looks for a use of a certain level of template
2878 /// parameter.
2879 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
2881 
2882  unsigned Depth;
2883 
2884  // Whether we're looking for a use of a template parameter that makes the
2885  // overall construct type-dependent / a dependent type. This is strictly
2886  // best-effort for now; we may fail to match at all for a dependent type
2887  // in some cases if this is set.
2888  bool IgnoreNonTypeDependent;
2889 
2890  bool Match;
2891  SourceLocation MatchLoc;
2892 
2893  DependencyChecker(unsigned Depth, bool IgnoreNonTypeDependent)
2894  : Depth(Depth), IgnoreNonTypeDependent(IgnoreNonTypeDependent),
2895  Match(false) {}
2896 
2897  DependencyChecker(TemplateParameterList *Params, bool IgnoreNonTypeDependent)
2898  : IgnoreNonTypeDependent(IgnoreNonTypeDependent), Match(false) {
2899  NamedDecl *ND = Params->getParam(0);
2900  if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
2901  Depth = PD->getDepth();
2902  } else if (NonTypeTemplateParmDecl *PD =
2903  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
2904  Depth = PD->getDepth();
2905  } else {
2906  Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
2907  }
2908  }
2909 
2910  bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
2911  if (ParmDepth >= Depth) {
2912  Match = true;
2913  MatchLoc = Loc;
2914  return true;
2915  }
2916  return false;
2917  }
2918 
2919  bool TraverseStmt(Stmt *S, DataRecursionQueue *Q = nullptr) {
2920  // Prune out non-type-dependent expressions if requested. This can
2921  // sometimes result in us failing to find a template parameter reference
2922  // (if a value-dependent expression creates a dependent type), but this
2923  // mode is best-effort only.
2924  if (auto *E = dyn_cast_or_null<Expr>(S))
2925  if (IgnoreNonTypeDependent && !E->isTypeDependent())
2926  return true;
2927  return super::TraverseStmt(S, Q);
2928  }
2929 
2930  bool TraverseTypeLoc(TypeLoc TL) {
2931  if (IgnoreNonTypeDependent && !TL.isNull() &&
2932  !TL.getType()->isDependentType())
2933  return true;
2934  return super::TraverseTypeLoc(TL);
2935  }
2936 
2937  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
2938  return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
2939  }
2940 
2941  bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
2942  // For a best-effort search, keep looking until we find a location.
2943  return IgnoreNonTypeDependent || !Matches(T->getDepth());
2944  }
2945 
2946  bool TraverseTemplateName(TemplateName N) {
2947  if (TemplateTemplateParmDecl *PD =
2948  dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
2949  if (Matches(PD->getDepth()))
2950  return false;
2951  return super::TraverseTemplateName(N);
2952  }
2953 
2954  bool VisitDeclRefExpr(DeclRefExpr *E) {
2955  if (NonTypeTemplateParmDecl *PD =
2956  dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
2957  if (Matches(PD->getDepth(), E->getExprLoc()))
2958  return false;
2959  return super::VisitDeclRefExpr(E);
2960  }
2961 
2962  bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
2963  return TraverseType(T->getReplacementType());
2964  }
2965 
2966  bool
2967  VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
2968  return TraverseTemplateArgument(T->getArgumentPack());
2969  }
2970 
2971  bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
2972  return TraverseType(T->getInjectedSpecializationType());
2973  }
2974 };
2975 } // end anonymous namespace
2976 
2977 /// Determines whether a given type depends on the given parameter
2978 /// list.
2979 static bool
2981  if (!Params->size())
2982  return false;
2983 
2984  DependencyChecker Checker(Params, /*IgnoreNonTypeDependent*/false);
2985  Checker.TraverseType(T);
2986  return Checker.Match;
2987 }
2988 
2989 // Find the source range corresponding to the named type in the given
2990 // nested-name-specifier, if any.
2992  QualType T,
2993  const CXXScopeSpec &SS) {
2995  while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
2996  if (const Type *CurType = NNS->getAsType()) {
2997  if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
2998  return NNSLoc.getTypeLoc().getSourceRange();
2999  } else
3000  break;
3001 
3002  NNSLoc = NNSLoc.getPrefix();
3003  }
3004 
3005  return SourceRange();
3006 }
3007 
3008 /// Match the given template parameter lists to the given scope
3009 /// specifier, returning the template parameter list that applies to the
3010 /// name.
3011 ///
3012 /// \param DeclStartLoc the start of the declaration that has a scope
3013 /// specifier or a template parameter list.
3014 ///
3015 /// \param DeclLoc The location of the declaration itself.
3016 ///
3017 /// \param SS the scope specifier that will be matched to the given template
3018 /// parameter lists. This scope specifier precedes a qualified name that is
3019 /// being declared.
3020 ///
3021 /// \param TemplateId The template-id following the scope specifier, if there
3022 /// is one. Used to check for a missing 'template<>'.
3023 ///
3024 /// \param ParamLists the template parameter lists, from the outermost to the
3025 /// innermost template parameter lists.
3026 ///
3027 /// \param IsFriend Whether to apply the slightly different rules for
3028 /// matching template parameters to scope specifiers in friend
3029 /// declarations.
3030 ///
3031 /// \param IsMemberSpecialization will be set true if the scope specifier
3032 /// denotes a fully-specialized type, and therefore this is a declaration of
3033 /// a member specialization.
3034 ///
3035 /// \returns the template parameter list, if any, that corresponds to the
3036 /// name that is preceded by the scope specifier @p SS. This template
3037 /// parameter list may have template parameters (if we're declaring a
3038 /// template) or may have no template parameters (if we're declaring a
3039 /// template specialization), or may be NULL (if what we're declaring isn't
3040 /// itself a template).
3042  SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
3043  TemplateIdAnnotation *TemplateId,
3044  ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
3045  bool &IsMemberSpecialization, bool &Invalid, bool SuppressDiagnostic) {
3046  IsMemberSpecialization = false;
3047  Invalid = false;
3048 
3049  // The sequence of nested types to which we will match up the template
3050  // parameter lists. We first build this list by starting with the type named
3051  // by the nested-name-specifier and walking out until we run out of types.
3052  SmallVector<QualType, 4> NestedTypes;
3053  QualType T;
3054  if (SS.getScopeRep()) {
3055  if (CXXRecordDecl *Record
3056  = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
3057  T = Context.getTypeDeclType(Record);
3058  else
3059  T = QualType(SS.getScopeRep()->getAsType(), 0);
3060  }
3061 
3062  // If we found an explicit specialization that prevents us from needing
3063  // 'template<>' headers, this will be set to the location of that
3064  // explicit specialization.
3065  SourceLocation ExplicitSpecLoc;
3066 
3067  while (!T.isNull()) {
3068  NestedTypes.push_back(T);
3069 
3070  // Retrieve the parent of a record type.
3071  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3072  // If this type is an explicit specialization, we're done.
3074  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3075  if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
3076  Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
3077  ExplicitSpecLoc = Spec->getLocation();
3078  break;
3079  }
3080  } else if (Record->getTemplateSpecializationKind()
3082  ExplicitSpecLoc = Record->getLocation();
3083  break;
3084  }
3085 
3086  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
3087  T = Context.getTypeDeclType(Parent);
3088  else
3089  T = QualType();
3090  continue;
3091  }
3092 
3093  if (const TemplateSpecializationType *TST
3095  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3096  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
3097  T = Context.getTypeDeclType(Parent);
3098  else
3099  T = QualType();
3100  continue;
3101  }
3102  }
3103 
3104  // Look one step prior in a dependent template specialization type.
3105  if (const DependentTemplateSpecializationType *DependentTST
3107  if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
3108  T = QualType(NNS->getAsType(), 0);
3109  else
3110  T = QualType();
3111  continue;
3112  }
3113 
3114  // Look one step prior in a dependent name type.
3115  if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
3116  if (NestedNameSpecifier *NNS = DependentName->getQualifier())
3117  T = QualType(NNS->getAsType(), 0);
3118  else
3119  T = QualType();
3120  continue;
3121  }
3122 
3123  // Retrieve the parent of an enumeration type.
3124  if (const EnumType *EnumT = T->getAs<EnumType>()) {
3125  // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
3126  // check here.
3127  EnumDecl *Enum = EnumT->getDecl();
3128 
3129  // Get to the parent type.
3130  if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
3131  T = Context.getTypeDeclType(Parent);
3132  else
3133  T = QualType();
3134  continue;
3135  }
3136 
3137  T = QualType();
3138  }
3139  // Reverse the nested types list, since we want to traverse from the outermost
3140  // to the innermost while checking template-parameter-lists.
3141  std::reverse(NestedTypes.begin(), NestedTypes.end());
3142 
3143  // C++0x [temp.expl.spec]p17:
3144  // A member or a member template may be nested within many
3145  // enclosing class templates. In an explicit specialization for
3146  // such a member, the member declaration shall be preceded by a
3147  // template<> for each enclosing class template that is
3148  // explicitly specialized.
3149  bool SawNonEmptyTemplateParameterList = false;
3150 
3151  auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
3152  if (SawNonEmptyTemplateParameterList) {
3153  if (!SuppressDiagnostic)
3154  Diag(DeclLoc, diag::err_specialize_member_of_template)
3155  << !Recovery << Range;
3156  Invalid = true;
3157  IsMemberSpecialization = false;
3158  return true;
3159  }
3160 
3161  return false;
3162  };
3163 
3164  auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
3165  // Check that we can have an explicit specialization here.
3166  if (CheckExplicitSpecialization(Range, true))
3167  return true;
3168 
3169  // We don't have a template header, but we should.
3170  SourceLocation ExpectedTemplateLoc;
3171  if (!ParamLists.empty())
3172  ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
3173  else
3174  ExpectedTemplateLoc = DeclStartLoc;
3175 
3176  if (!SuppressDiagnostic)
3177  Diag(DeclLoc, diag::err_template_spec_needs_header)
3178  << Range
3179  << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
3180  return false;
3181  };
3182 
3183  unsigned ParamIdx = 0;
3184  for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
3185  ++TypeIdx) {
3186  T = NestedTypes[TypeIdx];
3187 
3188  // Whether we expect a 'template<>' header.
3189  bool NeedEmptyTemplateHeader = false;
3190 
3191  // Whether we expect a template header with parameters.
3192  bool NeedNonemptyTemplateHeader = false;
3193 
3194  // For a dependent type, the set of template parameters that we
3195  // expect to see.
3196  TemplateParameterList *ExpectedTemplateParams = nullptr;
3197 
3198  // C++0x [temp.expl.spec]p15:
3199  // A member or a member template may be nested within many enclosing
3200  // class templates. In an explicit specialization for such a member, the
3201  // member declaration shall be preceded by a template<> for each
3202  // enclosing class template that is explicitly specialized.
3203  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
3205  = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
3206  ExpectedTemplateParams = Partial->getTemplateParameters();
3207  NeedNonemptyTemplateHeader = true;
3208  } else if (Record->isDependentType()) {
3209  if (Record->getDescribedClassTemplate()) {
3210  ExpectedTemplateParams = Record->getDescribedClassTemplate()
3211  ->getTemplateParameters();
3212  NeedNonemptyTemplateHeader = true;
3213  }
3214  } else if (ClassTemplateSpecializationDecl *Spec
3215  = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
3216  // C++0x [temp.expl.spec]p4:
3217  // Members of an explicitly specialized class template are defined
3218  // in the same manner as members of normal classes, and not using
3219  // the template<> syntax.
3220  if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
3221  NeedEmptyTemplateHeader = true;
3222  else
3223  continue;
3224  } else if (Record->getTemplateSpecializationKind()) {
3225  if (Record->getTemplateSpecializationKind()
3227  TypeIdx == NumTypes - 1)
3228  IsMemberSpecialization = true;
3229 
3230  continue;
3231  }
3232  } else if (const TemplateSpecializationType *TST
3234  if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
3235  ExpectedTemplateParams = Template->getTemplateParameters();
3236  NeedNonemptyTemplateHeader = true;
3237  }
3238  } else if (T->getAs<DependentTemplateSpecializationType>()) {
3239  // FIXME: We actually could/should check the template arguments here
3240  // against the corresponding template parameter list.
3241  NeedNonemptyTemplateHeader = false;
3242  }
3243 
3244  // C++ [temp.expl.spec]p16:
3245  // In an explicit specialization declaration for a member of a class
3246  // template or a member template that ap- pears in namespace scope, the
3247  // member template and some of its enclosing class templates may remain
3248  // unspecialized, except that the declaration shall not explicitly
3249  // specialize a class member template if its en- closing class templates
3250  // are not explicitly specialized as well.
3251  if (ParamIdx < ParamLists.size()) {
3252  if (ParamLists[ParamIdx]->size() == 0) {
3253  if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3254  false))
3255  return nullptr;
3256  } else
3257  SawNonEmptyTemplateParameterList = true;
3258  }
3259 
3260  if (NeedEmptyTemplateHeader) {
3261  // If we're on the last of the types, and we need a 'template<>' header
3262  // here, then it's a member specialization.
3263  if (TypeIdx == NumTypes - 1)
3264  IsMemberSpecialization = true;
3265 
3266  if (ParamIdx < ParamLists.size()) {
3267  if (ParamLists[ParamIdx]->size() > 0) {
3268  // The header has template parameters when it shouldn't. Complain.
3269  if (!SuppressDiagnostic)
3270  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3271  diag::err_template_param_list_matches_nontemplate)
3272  << T
3273  << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
3274  ParamLists[ParamIdx]->getRAngleLoc())
3275  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3276  Invalid = true;
3277  return nullptr;
3278  }
3279 
3280  // Consume this template header.
3281  ++ParamIdx;
3282  continue;
3283  }
3284 
3285  if (!IsFriend)
3286  if (DiagnoseMissingExplicitSpecialization(
3287  getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
3288  return nullptr;
3289 
3290  continue;
3291  }
3292 
3293  if (NeedNonemptyTemplateHeader) {
3294  // In friend declarations we can have template-ids which don't
3295  // depend on the corresponding template parameter lists. But
3296  // assume that empty parameter lists are supposed to match this
3297  // template-id.
3298  if (IsFriend && T->isDependentType()) {
3299  if (ParamIdx < ParamLists.size() &&
3300  DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
3301  ExpectedTemplateParams = nullptr;
3302  else
3303  continue;
3304  }
3305 
3306  if (ParamIdx < ParamLists.size()) {
3307  // Check the template parameter list, if we can.
3308  if (ExpectedTemplateParams &&
3309  !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
3310  ExpectedTemplateParams,
3311  !SuppressDiagnostic, TPL_TemplateMatch))
3312  Invalid = true;
3313 
3314  if (!Invalid &&
3315  CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
3316  TPC_ClassTemplateMember))
3317  Invalid = true;
3318 
3319  ++ParamIdx;
3320  continue;
3321  }
3322 
3323  if (!SuppressDiagnostic)
3324  Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
3325  << T
3326  << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
3327  Invalid = true;
3328  continue;
3329  }
3330  }
3331 
3332  // If there were at least as many template-ids as there were template
3333  // parameter lists, then there are no template parameter lists remaining for
3334  // the declaration itself.
3335  if (ParamIdx >= ParamLists.size()) {
3336  if (TemplateId && !IsFriend) {
3337  // We don't have a template header for the declaration itself, but we
3338  // should.
3339  DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
3340  TemplateId->RAngleLoc));
3341 
3342  // Fabricate an empty template parameter list for the invented header.
3344  SourceLocation(), None,
3345  SourceLocation(), nullptr);
3346  }
3347 
3348  return nullptr;
3349  }
3350 
3351  // If there were too many template parameter lists, complain about that now.
3352  if (ParamIdx < ParamLists.size() - 1) {
3353  bool HasAnyExplicitSpecHeader = false;
3354  bool AllExplicitSpecHeaders = true;
3355  for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
3356  if (ParamLists[I]->size() == 0)
3357  HasAnyExplicitSpecHeader = true;
3358  else
3359  AllExplicitSpecHeaders = false;
3360  }
3361 
3362  if (!SuppressDiagnostic)
3363  Diag(ParamLists[ParamIdx]->getTemplateLoc(),
3364  AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
3365  : diag::err_template_spec_extra_headers)
3366  << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
3367  ParamLists[ParamLists.size() - 2]->getRAngleLoc());
3368 
3369  // If there was a specialization somewhere, such that 'template<>' is
3370  // not required, and there were any 'template<>' headers, note where the
3371  // specialization occurred.
3372  if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader &&
3373  !SuppressDiagnostic)
3374  Diag(ExplicitSpecLoc,
3375  diag::note_explicit_template_spec_does_not_need_header)
3376  << NestedTypes.back();
3377 
3378  // We have a template parameter list with no corresponding scope, which
3379  // means that the resulting template declaration can't be instantiated
3380  // properly (we'll end up with dependent nodes when we shouldn't).
3381  if (!AllExplicitSpecHeaders)
3382  Invalid = true;
3383  }
3384 
3385  // C++ [temp.expl.spec]p16:
3386  // In an explicit specialization declaration for a member of a class
3387  // template or a member template that ap- pears in namespace scope, the
3388  // member template and some of its enclosing class templates may remain
3389  // unspecialized, except that the declaration shall not explicitly
3390  // specialize a class member template if its en- closing class templates
3391  // are not explicitly specialized as well.
3392  if (ParamLists.back()->size() == 0 &&
3393  CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
3394  false))
3395  return nullptr;
3396 
3397  // Return the last template parameter list, which corresponds to the
3398  // entity being declared.
3399  return ParamLists.back();
3400 }
3401 
3403  if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
3404  Diag(Template->getLocation(), diag::note_template_declared_here)
3405  << (isa<FunctionTemplateDecl>(Template)
3406  ? 0
3407  : isa<ClassTemplateDecl>(Template)
3408  ? 1
3409  : isa<VarTemplateDecl>(Template)
3410  ? 2
3411  : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
3412  << Template->getDeclName();
3413  return;
3414  }
3415 
3416  if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
3417  for (OverloadedTemplateStorage::iterator I = OST->begin(),
3418  IEnd = OST->end();
3419  I != IEnd; ++I)
3420  Diag((*I)->getLocation(), diag::note_template_declared_here)
3421  << 0 << (*I)->getDeclName();
3422 
3423  return;
3424  }
3425 }
3426 
3427 static QualType
3429  const SmallVectorImpl<TemplateArgument> &Converted,
3430  SourceLocation TemplateLoc,
3431  TemplateArgumentListInfo &TemplateArgs) {
3432  ASTContext &Context = SemaRef.getASTContext();
3433  switch (BTD->getBuiltinTemplateKind()) {
3434  case BTK__make_integer_seq: {
3435  // Specializations of __make_integer_seq<S, T, N> are treated like
3436  // S<T, 0, ..., N-1>.
3437 
3438  // C++14 [inteseq.intseq]p1:
3439  // T shall be an integer type.
3440  if (!Converted[1].getAsType()->isIntegralType(Context)) {
3441  SemaRef.Diag(TemplateArgs[1].getLocation(),
3442  diag::err_integer_sequence_integral_element_type);
3443  return QualType();
3444  }
3445 
3446  // C++14 [inteseq.make]p1:
3447  // If N is negative the program is ill-formed.
3448  TemplateArgument NumArgsArg = Converted[2];
3449  llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
3450  if (NumArgs < 0) {
3451  SemaRef.Diag(TemplateArgs[2].getLocation(),
3452  diag::err_integer_sequence_negative_length);
3453  return QualType();
3454  }
3455 
3456  QualType ArgTy = NumArgsArg.getIntegralType();
3457  TemplateArgumentListInfo SyntheticTemplateArgs;
3458  // The type argument gets reused as the first template argument in the
3459  // synthetic template argument list.
3460  SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
3461  // Expand N into 0 ... N-1.
3462  for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
3463  I < NumArgs; ++I) {
3464  TemplateArgument TA(Context, I, ArgTy);
3465  SyntheticTemplateArgs.addArgument(SemaRef.getTrivialTemplateArgumentLoc(
3466  TA, ArgTy, TemplateArgs[2].getLocation()));
3467  }
3468  // The first template argument will be reused as the template decl that
3469  // our synthetic template arguments will be applied to.
3470  return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
3471  TemplateLoc, SyntheticTemplateArgs);
3472  }
3473 
3475  // Specializations of
3476  // __type_pack_element<Index, T_1, ..., T_N>
3477  // are treated like T_Index.
3478  assert(Converted.size() == 2 &&
3479  "__type_pack_element should be given an index and a parameter pack");
3480 
3481  // If the Index is out of bounds, the program is ill-formed.
3482  TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
3483  llvm::APSInt Index = IndexArg.getAsIntegral();
3484  assert(Index >= 0 && "the index used with __type_pack_element should be of "
3485  "type std::size_t, and hence be non-negative");
3486  if (Index >= Ts.pack_size()) {
3487  SemaRef.Diag(TemplateArgs[0].getLocation(),
3488  diag::err_type_pack_element_out_of_bounds);
3489  return QualType();
3490  }
3491 
3492  // We simply return the type at index `Index`.
3493  auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
3494  return Nth->getAsType();
3495  }
3496  llvm_unreachable("unexpected BuiltinTemplateDecl!");
3497 }
3498 
3499 /// Determine whether this alias template is "enable_if_t".
3500 /// libc++ >=14 uses "__enable_if_t" in C++11 mode.
3501 static bool isEnableIfAliasTemplate(TypeAliasTemplateDecl *AliasTemplate) {
3502  return AliasTemplate->getName().equals("enable_if_t") ||
3503  AliasTemplate->getName().equals("__enable_if_t");
3504 }
3505 
3506 /// Collect all of the separable terms in the given condition, which
3507 /// might be a conjunction.
3508 ///
3509 /// FIXME: The right answer is to convert the logical expression into
3510 /// disjunctive normal form, so we can find the first failed term
3511 /// within each possible clause.
3512 static void collectConjunctionTerms(Expr *Clause,
3513  SmallVectorImpl<Expr *> &Terms) {
3514  if (auto BinOp = dyn_cast<BinaryOperator>(Clause->IgnoreParenImpCasts())) {
3515  if (BinOp->getOpcode() == BO_LAnd) {
3516  collectConjunctionTerms(BinOp->getLHS(), Terms);
3517  collectConjunctionTerms(BinOp->getRHS(), Terms);
3518  }
3519 
3520  return;
3521  }
3522 
3523  Terms.push_back(Clause);
3524 }
3525 
3526 // The ranges-v3 library uses an odd pattern of a top-level "||" with
3527 // a left-hand side that is value-dependent but never true. Identify
3528 // the idiom and ignore that term.
3530  // Top-level '||'.
3531  auto *BinOp = dyn_cast<BinaryOperator>(Cond->IgnoreParenImpCasts());
3532  if (!BinOp) return Cond;
3533 
3534  if (BinOp->getOpcode() != BO_LOr) return Cond;
3535 
3536  // With an inner '==' that has a literal on the right-hand side.
3537  Expr *LHS = BinOp->getLHS();
3538  auto *InnerBinOp = dyn_cast<BinaryOperator>(LHS->IgnoreParenImpCasts());
3539  if (!InnerBinOp) return Cond;
3540 
3541  if (InnerBinOp->getOpcode() != BO_EQ ||
3542  !isa<IntegerLiteral>(InnerBinOp->getRHS()))
3543  return Cond;
3544 
3545  // If the inner binary operation came from a macro expansion named
3546  // CONCEPT_REQUIRES or CONCEPT_REQUIRES_, return the right-hand side
3547  // of the '||', which is the real, user-provided condition.
3548  SourceLocation Loc = InnerBinOp->getExprLoc();
3549  if (!Loc.isMacroID()) return Cond;
3550 
3551  StringRef MacroName = PP.getImmediateMacroName(Loc);
3552  if (MacroName == "CONCEPT_REQUIRES" || MacroName == "CONCEPT_REQUIRES_")
3553  return BinOp->getRHS();
3554 
3555  return Cond;
3556 }
3557 
3558 namespace {
3559 
3560 // A PrinterHelper that prints more helpful diagnostics for some sub-expressions
3561 // within failing boolean expression, such as substituting template parameters
3562 // for actual types.
3563 class FailedBooleanConditionPrinterHelper : public PrinterHelper {
3564 public:
3565  explicit FailedBooleanConditionPrinterHelper(const PrintingPolicy &P)
3566  : Policy(P) {}
3567 
3568  bool handledStmt(Stmt *E, raw_ostream &OS) override {
3569  const auto *DR = dyn_cast<DeclRefExpr>(E);
3570  if (DR && DR->getQualifier()) {
3571  // If this is a qualified name, expand the template arguments in nested
3572  // qualifiers.
3573  DR->getQualifier()->print(OS, Policy, true);
3574  // Then print the decl itself.
3575  const ValueDecl *VD = DR->getDecl();
3576  OS << VD->getName();
3577  if (const auto *IV = dyn_cast<VarTemplateSpecializationDecl>(VD)) {
3578  // This is a template variable, print the expanded template arguments.
3580  OS, IV->getTemplateArgs().asArray(), Policy,
3581  IV->getSpecializedTemplate()->getTemplateParameters());
3582  }
3583  return true;
3584  }
3585  return false;
3586  }
3587 
3588 private:
3589  const PrintingPolicy Policy;
3590 };
3591 
3592 } // end anonymous namespace
3593 
3594 std::pair<Expr *, std::string>
3596  Cond = lookThroughRangesV3Condition(PP, Cond);
3597 
3598  // Separate out all of the terms in a conjunction.
3599  SmallVector<Expr *, 4> Terms;
3600  collectConjunctionTerms(Cond, Terms);
3601 
3602  // Determine which term failed.
3603  Expr *FailedCond = nullptr;
3604  for (Expr *Term : Terms) {
3605  Expr *TermAsWritten = Term->IgnoreParenImpCasts();
3606 
3607  // Literals are uninteresting.
3608  if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
3609  isa<IntegerLiteral>(TermAsWritten))
3610  continue;
3611 
3612  // The initialization of the parameter from the argument is
3613  // a constant-evaluated context.
3614  EnterExpressionEvaluationContext ConstantEvaluated(
3616 
3617  bool Succeeded;
3618  if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
3619  !Succeeded) {
3620  FailedCond = TermAsWritten;
3621  break;
3622  }
3623  }
3624  if (!FailedCond)
3625  FailedCond = Cond->IgnoreParenImpCasts();
3626 
3627  std::string Description;
3628  {
3629  llvm::raw_string_ostream Out(Description);
3630  PrintingPolicy Policy = getPrintingPolicy();
3631  Policy.PrintCanonicalTypes = true;
3632  FailedBooleanConditionPrinterHelper Helper(Policy);
3633  FailedCond->printPretty(Out, &Helper, Policy, 0, "\n", nullptr);
3634  }
3635  return { FailedCond, Description };
3636 }
3637 
3639  SourceLocation TemplateLoc,
3640  TemplateArgumentListInfo &TemplateArgs) {
3642  = Name.getUnderlying().getAsDependentTemplateName();
3643  if (DTN && DTN->isIdentifier())
3644  // When building a template-id where the template-name is dependent,
3645  // assume the template is a type template. Either our assumption is
3646  // correct, or the code is ill-formed and will be diagnosed when the
3647  // dependent name is substituted.
3649  DTN->getQualifier(),
3650  DTN->getIdentifier(),
3651  TemplateArgs);
3652 
3653  if (Name.getAsAssumedTemplateName() &&
3654  resolveAssumedTemplateNameAsType(/*Scope*/nullptr, Name, TemplateLoc))
3655  return QualType();
3656 
3657  TemplateDecl *Template = Name.getAsTemplateDecl();
3658  if (!Template || isa<FunctionTemplateDecl>(Template) ||
3659  isa<VarTemplateDecl>(Template) || isa<ConceptDecl>(Template)) {
3660  // We might have a substituted template template parameter pack. If so,
3661  // build a template specialization type for it.
3662  if (Name.getAsSubstTemplateTemplateParmPack())
3663  return Context.getTemplateSpecializationType(Name, TemplateArgs);
3664 
3665  Diag(TemplateLoc, diag::err_template_id_not_a_type)
3666  << Name;
3667  NoteAllFoundTemplates(Name);
3668  return QualType();
3669  }
3670 
3671  // Check that the template argument list is well-formed for this
3672  // template.
3674  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
3675  false, Converted,
3676  /*UpdateArgsWithConversion=*/true))
3677  return QualType();
3678 
3679  QualType CanonType;
3680 
3682  dyn_cast<TypeAliasTemplateDecl>(Template)) {
3683 
3684  // Find the canonical type for this type alias template specialization.
3685  TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
3686  if (Pattern->isInvalidDecl())
3687  return QualType();
3688 
3690  Converted);
3691 
3692  // Only substitute for the innermost template argument list.
3693  MultiLevelTemplateArgumentList TemplateArgLists;
3694  TemplateArgLists.addOuterTemplateArguments(&StackTemplateArgs);
3695  TemplateArgLists.addOuterRetainedLevels(
3696  AliasTemplate->getTemplateParameters()->getDepth());
3697 
3699  InstantiatingTemplate Inst(*this, TemplateLoc, Template);
3700  if (Inst.isInvalid())
3701  return QualType();
3702 
3703  CanonType = SubstType(Pattern->getUnderlyingType(),
3704  TemplateArgLists, AliasTemplate->getLocation(),
3705  AliasTemplate->getDeclName());
3706  if (CanonType.isNull()) {
3707  // If this was enable_if and we failed to find the nested type
3708  // within enable_if in a SFINAE context, dig out the specific
3709  // enable_if condition that failed and present that instead.
3711  if (auto DeductionInfo = isSFINAEContext()) {
3712  if (*DeductionInfo &&
3713  (*DeductionInfo)->hasSFINAEDiagnostic() &&
3714  (*DeductionInfo)->peekSFINAEDiagnostic().second.getDiagID() ==
3715  diag::err_typename_nested_not_found_enable_if &&
3716  TemplateArgs[0].getArgument().getKind()
3718  Expr *FailedCond;
3719  std::string FailedDescription;
3720  std::tie(FailedCond, FailedDescription) =
3721  findFailedBooleanCondition(TemplateArgs[0].getSourceExpression());
3722 
3723  // Remove the old SFINAE diagnostic.
3724  PartialDiagnosticAt OldDiag =
3726  (*DeductionInfo)->takeSFINAEDiagnostic(OldDiag);
3727 
3728  // Add a new SFINAE diagnostic specifying which condition
3729  // failed.
3730  (*DeductionInfo)->addSFINAEDiagnostic(
3731  OldDiag.first,
3732  PDiag(diag::err_typename_nested_not_found_requirement)
3733  << FailedDescription
3734  << FailedCond->getSourceRange());
3735  }
3736  }
3737  }
3738 
3739  return QualType();
3740  }
3741  } else if (Name.isDependent() ||
3743  TemplateArgs, Converted)) {
3744  // This class template specialization is a dependent
3745  // type. Therefore, its canonical type is another class template
3746  // specialization type that contains all of the converted
3747  // arguments in canonical form. This ensures that, e.g., A<T> and
3748  // A<T, T> have identical types when A is declared as:
3749  //
3750  // template<typename T, typename U = T> struct A;
3751  CanonType = Context.getCanonicalTemplateSpecializationType(Name, Converted);
3752 
3753  // This might work out to be a current instantiation, in which
3754  // case the canonical type needs to be the InjectedClassNameType.
3755  //
3756  // TODO: in theory this could be a simple hashtable lookup; most
3757  // changes to CurContext don't change the set of current
3758  // instantiations.
3759  if (isa<ClassTemplateDecl>(Template)) {
3760  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
3761  // If we get out to a namespace, we're done.
3762  if (Ctx->isFileContext()) break;
3763 
3764  // If this isn't a record, keep looking.
3765  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
3766  if (!Record) continue;
3767 
3768  // Look for one of the two cases with InjectedClassNameTypes
3769  // and check whether it's the same template.
3770  if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
3771  !Record->getDescribedClassTemplate())
3772  continue;
3773 
3774  // Fetch the injected class name type and check whether its
3775  // injected type is equal to the type we just built.
3776  QualType ICNT = Context.getTypeDeclType(Record);
3777  QualType Injected = cast<InjectedClassNameType>(ICNT)
3778  ->getInjectedSpecializationType();
3779 
3780  if (CanonType != Injected->getCanonicalTypeInternal())
3781  continue;
3782 
3783  // If so, the canonical type of this TST is the injected
3784  // class name type of the record we just found.
3785  assert(ICNT.isCanonical());
3786  CanonType = ICNT;
3787  break;
3788  }
3789  }
3790  } else if (ClassTemplateDecl *ClassTemplate
3791  = dyn_cast<ClassTemplateDecl>(Template)) {
3792  // Find the class template specialization declaration that
3793  // corresponds to these arguments.
3794  void *InsertPos = nullptr;
3796  = ClassTemplate->findSpecialization(Converted, InsertPos);
3797  if (!Decl) {
3798  // This is the first time we have referenced this class template
3799  // specialization. Create the canonical declaration and add it to
3800  // the set of specializations.
3802  Context, ClassTemplate->getTemplatedDecl()->getTagKind(),
3803  ClassTemplate->getDeclContext(),
3804  ClassTemplate->getTemplatedDecl()->getBeginLoc(),
3805  ClassTemplate->getLocation(), ClassTemplate, Converted, nullptr);
3806  ClassTemplate->AddSpecialization(Decl, InsertPos);
3807  if (ClassTemplate->isOutOfLine())
3808  Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
3809  }
3810 
3811  if (Decl->getSpecializationKind() == TSK_Undeclared &&
3812  ClassTemplate->getTemplatedDecl()->hasAttrs()) {
3813  InstantiatingTemplate Inst(*this, TemplateLoc, Decl);
3814  if (!Inst.isInvalid()) {
3815  MultiLevelTemplateArgumentList TemplateArgLists;
3816  TemplateArgLists.addOuterTemplateArguments(Converted);
3817  InstantiateAttrsForDecl(TemplateArgLists,
3818  ClassTemplate->getTemplatedDecl(), Decl);
3819  }
3820  }
3821 
3822  // Diagnose uses of this specialization.
3823  (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
3824 
3825  CanonType = Context.getTypeDeclType(Decl);
3826  assert(isa<RecordType>(CanonType) &&
3827  "type of non-dependent specialization is not a RecordType");
3828  } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
3829  CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
3830  TemplateArgs);
3831  }
3832 
3833  // Build the fully-sugared type for this class template
3834  // specialization, which refers back to the class template
3835  // specialization we created or found.
3836  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
3837 }
3838 
3840  TemplateNameKind &TNK,
3841  SourceLocation NameLoc,
3842  IdentifierInfo *&II) {
3843  assert(TNK == TNK_Undeclared_template && "not an undeclared template name");
3844 
3845  TemplateName Name = ParsedName.get();
3846  auto *ATN = Name.getAsAssumedTemplateName();
3847  assert(ATN && "not an assumed template name");
3848  II = ATN->getDeclName().getAsIdentifierInfo();
3849 
3850  if (!resolveAssumedTemplateNameAsType(S, Name, NameLoc, /*Diagnose*/false)) {
3851  // Resolved to a type template name.
3852  ParsedName = TemplateTy::make(Name);
3853  TNK = TNK_Type_template;
3854  }
3855 }
3856 
3858  SourceLocation NameLoc,
3859  bool Diagnose) {
3860  // We assumed this undeclared identifier to be an (ADL-only) function
3861  // template name, but it was used in a context where a type was required.
3862  // Try to typo-correct it now.
3863  AssumedTemplateStorage *ATN = Name.getAsAssumedTemplateName();
3864  assert(ATN && "not an assumed template name");
3865 
3866  LookupResult R(*this, ATN->getDeclName(), NameLoc, LookupOrdinaryName);
3867  struct CandidateCallback : CorrectionCandidateCallback {
3868  bool ValidateCandidate(const TypoCorrection &TC) override {
3869  return TC.getCorrectionDecl() &&
3871  }
3872  std::unique_ptr<CorrectionCandidateCallback> clone() override {
3873  return std::make_unique<CandidateCallback>(*this);
3874  }
3875  } FilterCCC;
3876 
3877  TypoCorrection Corrected =
3878  CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, nullptr,
3879  FilterCCC, CTK_ErrorRecovery);
3880  if (Corrected && Corrected.getFoundDecl()) {
3881  diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest)
3882  << ATN->getDeclName());
3883  Name = TemplateName(Corrected.getCorrectionDeclAs<TemplateDecl>());
3884  return false;
3885  }
3886 
3887  if (Diagnose)
3888  Diag(R.getNameLoc(), diag::err_no_template) << R.getLookupName();
3889  return true;
3890 }
3891 
3893  Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
3894  TemplateTy TemplateD, IdentifierInfo *TemplateII,
3895  SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
3896  ASTTemplateArgsPtr TemplateArgsIn, SourceLocation RAngleLoc,
3897  bool IsCtorOrDtorName, bool IsClassName) {
3898  if (SS.isInvalid())
3899  return true;
3900 
3901  if (!IsCtorOrDtorName && !IsClassName && SS.isSet()) {
3902  DeclContext *LookupCtx = computeDeclContext(SS, /*EnteringContext*/false);
3903 
3904  // C++ [temp.res]p3:
3905  // A qualified-id that refers to a type and in which the
3906  // nested-name-specifier depends on a template-parameter (14.6.2)
3907  // shall be prefixed by the keyword typename to indicate that the
3908  // qualified-id denotes a type, forming an
3909  // elaborated-type-specifier (7.1.5.3).
3910  if (!LookupCtx && isDependentScopeSpecifier(SS)) {
3911  Diag(SS.getBeginLoc(), diag::err_typename_missing_template)
3912  << SS.getScopeRep() << TemplateII->getName();
3913  // Recover as if 'typename' were specified.
3914  // FIXME: This is not quite correct recovery as we don't transform SS
3915  // into the corresponding dependent form (and we don't diagnose missing
3916  // 'template' keywords within SS as a result).
3917  return ActOnTypenameType(nullptr, SourceLocation(), SS, TemplateKWLoc,
3918  TemplateD, TemplateII, TemplateIILoc, LAngleLoc,
3919  TemplateArgsIn, RAngleLoc);
3920  }
3921 
3922  // Per C++ [class.qual]p2, if the template-id was an injected-class-name,
3923  // it's not actually allowed to be used as a type in most cases. Because
3924  // we annotate it before we know whether it's valid, we have to check for
3925  // this case here.
3926  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
3927  if (LookupRD && LookupRD->getIdentifier() == TemplateII) {
3928  Diag(TemplateIILoc,
3929  TemplateKWLoc.isInvalid()
3930  ? diag::err_out_of_line_qualified_id_type_names_constructor
3931  : diag::ext_out_of_line_qualified_id_type_names_constructor)
3932  << TemplateII << 0 /*injected-class-name used as template name*/
3933  << 1 /*if any keyword was present, it was 'template'*/;
3934  }
3935  }
3936 
3937  TemplateName Template = TemplateD.get();
3938  if (Template.getAsAssumedTemplateName() &&
3939  resolveAssumedTemplateNameAsType(S, Template, TemplateIILoc))
3940  return true;
3941 
3942  // Translate the parser's template argument list in our AST format.
3943  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
3944  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
3945 
3946  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
3947  QualType T
3949  DTN->getQualifier(),
3950  DTN->getIdentifier(),
3951  TemplateArgs);
3952  // Build type-source information.
3953  TypeLocBuilder TLB;
3957  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
3958  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3959  SpecTL.setTemplateNameLoc(TemplateIILoc);
3960  SpecTL.setLAngleLoc(LAngleLoc);
3961  SpecTL.setRAngleLoc(RAngleLoc);
3962  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
3963  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
3964  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
3965  }
3966 
3967  QualType Result = CheckTemplateIdType(Template, TemplateIILoc, TemplateArgs);
3968  if (Result.isNull())
3969  return true;
3970 
3971  // Build type-source information.
3972  TypeLocBuilder TLB;
3974  = TLB.push<TemplateSpecializationTypeLoc>(Result);
3975  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
3976  SpecTL.setTemplateNameLoc(TemplateIILoc);
3977  SpecTL.setLAngleLoc(LAngleLoc);
3978  SpecTL.setRAngleLoc(RAngleLoc);
3979  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
3980  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
3981 
3982  // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
3983  // constructor or destructor name (in such a case, the scope specifier
3984  // will be attached to the enclosing Decl or Expr node).
3985  if (SS.isNotEmpty() && !IsCtorOrDtorName) {
3986  // Create an elaborated-type-specifier containing the nested-name-specifier.
3987  Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
3988  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
3990  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
3991  }
3992 
3993  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
3994 }
3995 
3997  TypeSpecifierType TagSpec,
3998  SourceLocation TagLoc,
3999  CXXScopeSpec &SS,
4000  SourceLocation TemplateKWLoc,
4001  TemplateTy TemplateD,
4002  SourceLocation TemplateLoc,
4003  SourceLocation LAngleLoc,
4004  ASTTemplateArgsPtr TemplateArgsIn,
4005  SourceLocation RAngleLoc) {
4006  if (SS.isInvalid())
4007  return TypeResult(true);
4008 
4009  TemplateName Template = TemplateD.get();
4010 
4011  // Translate the parser's template argument list in our AST format.
4012  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
4013  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
4014 
4015  // Determine the tag kind
4017  ElaboratedTypeKeyword Keyword
4019 
4020  if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
4022  DTN->getQualifier(),
4023  DTN->getIdentifier(),
4024  TemplateArgs);
4025 
4026  // Build type-source information.
4027  TypeLocBuilder TLB;
4030  SpecTL.setElaboratedKeywordLoc(TagLoc);
4031  SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
4032  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4033  SpecTL.setTemplateNameLoc(TemplateLoc);
4034  SpecTL.setLAngleLoc(LAngleLoc);
4035  SpecTL.setRAngleLoc(RAngleLoc);
4036  for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
4037  SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
4038  return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
4039  }
4040 
4041  if (TypeAliasTemplateDecl *TAT =
4042  dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
4043  // C++0x [dcl.type.elab]p2:
4044  // If the identifier resolves to a typedef-name or the simple-template-id
4045  // resolves to an alias template specialization, the
4046  // elaborated-type-specifier is ill-formed.
4047  Diag(TemplateLoc, diag::err_tag_reference_non_tag)
4048  << TAT << NTK_TypeAliasTemplate << TagKind;
4049  Diag(TAT->getLocation(), diag::note_declared_at);
4050  }
4051 
4052  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
4053  if (Result.isNull())
4054  return TypeResult(true);
4055 
4056  // Check the tag kind
4057  if (const RecordType *RT = Result->getAs<RecordType>()) {
4058  RecordDecl *D = RT->getDecl();
4059 
4061  assert(Id && "templated class must have an identifier");
4062 
4063  if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
4064  TagLoc, Id)) {
4065  Diag(TagLoc, diag::err_use_with_wrong_tag)
4066  << Result
4068  Diag(D->getLocation(), diag::note_previous_use);
4069  }
4070  }
4071 
4072  // Provide source-location information for the template specialization.
4073  TypeLocBuilder TLB;
4075  = TLB.push<TemplateSpecializationTypeLoc>(Result);
4076  SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
4077  SpecTL.setTemplateNameLoc(TemplateLoc);
4078  SpecTL.setLAngleLoc(LAngleLoc);
4079  SpecTL.setRAngleLoc(RAngleLoc);
4080  for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
4081  SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
4082 
4083  // Construct an elaborated type containing the nested-name-specifier (if any)
4084  // and tag keyword.
4085  Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
4086  ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
4087  ElabTL.setElaboratedKeywordLoc(TagLoc);
4088  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
4089  return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
4090 }
4091 
4092 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
4093  NamedDecl *PrevDecl,
4094  SourceLocation Loc,
4096 
4098 
4100  const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
4101  switch (Arg.getKind()) {
4108  return false;
4109 
4110  case TemplateArgument::Type: {
4111  QualType Type = Arg.getAsType();
4112  const TemplateTypeParmType *TPT =
4114  return TPT && !Type.hasQualifiers() &&
4115  TPT->getDepth() == Depth && TPT->getIndex() == Index;
4116  }
4117 
4119  DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
4120  if (!DRE || !DRE->getDecl())
4121  return false;
4122  const NonTypeTemplateParmDecl *NTTP =
4123  dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
4124  return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
4125  }
4126 
4128  const TemplateTemplateParmDecl *TTP =
4129  dyn_cast_or_null<TemplateTemplateParmDecl>(
4131  return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
4132  }
4133  llvm_unreachable("unexpected kind of template argument");
4134 }
4135 
4138  if (Params->size() != Args.size())
4139  return false;
4140 
4141  unsigned Depth = Params->getDepth();
4142 
4143  for (unsigned I = 0, N = Args.size(); I != N; ++I) {
4144  TemplateArgument Arg = Args[I];
4145 
4146  // If the parameter is a pack expansion, the argument must be a pack
4147  // whose only element is a pack expansion.
4148  if (Params->getParam(I)->isParameterPack()) {
4149  if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
4150  !Arg.pack_begin()->isPackExpansion())
4151  return false;
4152  Arg = Arg.pack_begin()->getPackExpansionPattern();
4153  }
4154 
4156  return false;
4157  }
4158 
4159  return true;
4160 }
4161 
4162 template<typename PartialSpecDecl>
4163 static void checkMoreSpecializedThanPrimary(Sema &S, PartialSpecDecl *Partial) {
4164  if (Partial->getDeclContext()->isDependentContext())
4165  return;
4166 
4167  // FIXME: Get the TDK from deduction in order to provide better diagnostics
4168  // for non-substitution-failure issues?
4169  TemplateDeductionInfo Info(Partial->getLocation());
4170  if (S.isMoreSpecializedThanPrimary(Partial, Info))
4171  return;
4172 
4173  auto *Template = Partial->getSpecializedTemplate();
4174  S.Diag(Partial->getLocation(),
4175  diag::ext_partial_spec_not_more_specialized_than_primary)
4176  << isa<VarTemplateDecl>(Template);
4177 
4178  if (Info.hasSFINAEDiagnostic()) {
4181  Info.takeSFINAEDiagnostic(Diag);
4182  SmallString<128> SFINAEArgString;
4183  Diag.second.EmitToString(S.getDiagnostics(), SFINAEArgString);
4184  S.Diag(Diag.first,
4185  diag::note_partial_spec_not_more_specialized_than_primary)
4186  << SFINAEArgString;
4187  }
4188 
4189  S.Diag(Template->getLocation(), diag::note_template_decl_here);
4190  SmallVector<const Expr *, 3> PartialAC, TemplateAC;
4191  Template->getAssociatedConstraints(TemplateAC);
4192  Partial->getAssociatedConstraints(PartialAC);
4193  S.MaybeEmitAmbiguousAtomicConstraintsDiagnostic(Partial, PartialAC, Template,
4194  TemplateAC);
4195 }
4196 
4197 static void
4199  const llvm::SmallBitVector &DeducibleParams) {
4200  for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
4201  if (!DeducibleParams[I]) {
4202  NamedDecl *Param = TemplateParams->getParam(I);
4203  if (Param->getDeclName())
4204  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4205  << Param->getDeclName();
4206  else
4207  S.Diag(Param->getLocation(), diag::note_non_deducible_parameter)
4208  << "(anonymous)";
4209  }
4210  }
4211 }
4212 
4213 
4214 template<typename PartialSpecDecl>
4216  PartialSpecDecl *Partial) {
4217  // C++1z [temp.class.spec]p8: (DR1495)
4218  // - The specialization shall be more specialized than the primary
4219  // template (14.5.5.2).
4220  checkMoreSpecializedThanPrimary(S, Partial);
4221 
4222  // C++ [temp.class.spec]p8: (DR1315)
4223  // - Each template-parameter shall appear at least once in the
4224  // template-id outside a non-deduced context.
4225  // C++1z [temp.class.spec.match]p3 (P0127R2)
4226  // If the template arguments of a partial specialization cannot be
4227  // deduced because of the structure of its template-parameter-list
4228  // and the template-id, the program is ill-formed.
4229  auto *TemplateParams = Partial->getTemplateParameters();
4230  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4231  S.MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
4232  TemplateParams->getDepth(), DeducibleParams);
4233 
4234  if (!DeducibleParams.all()) {
4235  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4236  S.Diag(Partial->getLocation(), diag::ext_partial_specs_not_deducible)
4237  << isa<VarTemplatePartialSpecializationDecl>(Partial)
4238  << (NumNonDeducible > 1)
4239  << SourceRange(Partial->getLocation(),
4240  Partial->getTemplateArgsAsWritten()->RAngleLoc);
4241  noteNonDeducibleParameters(S, TemplateParams, DeducibleParams);
4242  }
4243 }
4244 
4247  checkTemplatePartialSpecialization(*this, Partial);
4248 }
4249 
4252  checkTemplatePartialSpecialization(*this, Partial);
4253 }
4254 
4256  // C++1z [temp.param]p11:
4257  // A template parameter of a deduction guide template that does not have a
4258  // default-argument shall be deducible from the parameter-type-list of the
4259  // deduction guide template.
4260  auto *TemplateParams = TD->getTemplateParameters();
4261  llvm::SmallBitVector DeducibleParams(TemplateParams->size());
4262  MarkDeducedTemplateParameters(TD, DeducibleParams);
4263  for (unsigned I = 0; I != TemplateParams->size(); ++I) {
4264  // A parameter pack is deducible (to an empty pack).
4265  auto *Param = TemplateParams->getParam(I);
4266  if (Param->isParameterPack() || hasVisibleDefaultArgument(Param))
4267  DeducibleParams[I] = true;
4268  }
4269 
4270  if (!DeducibleParams.all()) {
4271  unsigned NumNonDeducible = DeducibleParams.size() - DeducibleParams.count();
4272  Diag(TD->getLocation(), diag::err_deduction_guide_template_not_deducible)
4273  << (NumNonDeducible > 1);
4274  noteNonDeducibleParameters(*this, TemplateParams, DeducibleParams);
4275  }
4276 }
4277 
4279  Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
4280  TemplateParameterList *TemplateParams, StorageClass SC,
4281  bool IsPartialSpecialization) {
4282  // D must be variable template id.
4284  "Variable template specialization is declared with a template it.");
4285 
4286  TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
4287  TemplateArgumentListInfo TemplateArgs =
4288  makeTemplateArgumentListInfo(*this, *TemplateId);
4289  SourceLocation TemplateNameLoc = D.getIdentifierLoc();
4290  SourceLocation LAngleLoc = TemplateId->LAngleLoc;
4291  SourceLocation RAngleLoc = TemplateId->RAngleLoc;
4292 
4293  TemplateName Name = TemplateId->Template.get();
4294 
4295  // The template-id must name a variable template.
4296  VarTemplateDecl *VarTemplate =
4297  dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
4298  if (!VarTemplate) {
4299  NamedDecl *FnTemplate;
4300  if (auto *OTS = Name.getAsOverloadedTemplate())
4301  FnTemplate = *OTS->begin();
4302  else
4303  FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
4304  if (FnTemplate)
4305  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
4306  << FnTemplate->getDeclName();
4307  return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
4309  }
4310 
4311  // Check for unexpanded parameter packs in any of the template arguments.
4312  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
4313  if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
4314  UPPC_PartialSpecialization))
4315  return true;
4316 
4317  // Check that the template argument list is well-formed for this
4318  // template.
4320  if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
4321  false, Converted,
4322  /*UpdateArgsWithConversion=*/true))
4323  return true;
4324 
4325  // Find the variable template (partial) specialization declaration that
4326  // corresponds to these arguments.
4328  if (CheckTemplatePartialSpecializationArgs(TemplateNameLoc, VarTemplate,
4329  TemplateArgs.size(), Converted))
4330  return true;
4331 
4332  // FIXME: Move these checks to CheckTemplatePartialSpecializationArgs so we
4333  // also do them during instantiation.
4334  if (!Name.isDependent() &&
4336  Converted)) {
4337  Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
4338  << VarTemplate->getDeclName();
4339  IsPartialSpecialization = false;
4340  }
4341 
4343  Converted) &&
4344  (!Context.getLangOpts().CPlusPlus20 ||
4345  !TemplateParams->hasAssociatedConstraints())) {
4346  // C++ [temp.class.spec]p9b3:
4347  //
4348  // -- The argument list of the specialization shall not be identical
4349  // to the implicit argument list of the primary template.
4350  Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
4351  << /*variable template*/ 1
4352  << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
4353  << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
4354  // FIXME: Recover from this by treating the declaration as a redeclaration
4355  // of the primary template.
4356  return true;
4357  }
4358  }
4359 
4360  void *InsertPos = nullptr;
4361  VarTemplateSpecializationDecl *PrevDecl = nullptr;
4362 
4364  PrevDecl = VarTemplate->findPartialSpecialization(Converted, TemplateParams,
4365  InsertPos);
4366  else
4367  PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
4368 
4370 
4371  // Check whether we can declare a variable template specialization in
4372  // the current scope.
4373  if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
4374  TemplateNameLoc,
4376  return true;
4377 
4378  if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
4379  // Since the only prior variable template specialization with these
4380  // arguments was referenced but not declared, reuse that
4381  // declaration node as our own, updating its source location and
4382  // the list of outer template parameters to reflect our new declaration.
4383  Specialization = PrevDecl;
4384  Specialization->setLocation(TemplateNameLoc);
4385  PrevDecl = nullptr;
4386  } else if (IsPartialSpecialization) {
4387  // Create a new class template partial specialization declaration node.
4389  cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
4392  Context, VarTemplate->getDeclContext(), TemplateKWLoc,
4393  TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
4394  Converted, TemplateArgs);
4395 
4396  if (!PrevPartial)
4397  VarTemplate->AddPartialSpecialization(Partial, InsertPos);
4398  Specialization = Partial;
4399 
4400  // If we are providing an explicit specialization of a member variable
4401  // template specialization, make a note of that.
4402  if (PrevPartial && PrevPartial->getInstantiatedFromMember())
4403  PrevPartial->setMemberSpecialization();
4404 
4405  CheckTemplatePartialSpecialization(Partial);
4406  } else {
4407  // Create a new class template specialization declaration node for
4408  // this explicit specialization or friend declaration.
4410  Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
4411  VarTemplate, DI->getType(), DI, SC, Converted);
4412  Specialization->setTemplateArgsInfo(TemplateArgs);
4413 
4414  if (!PrevDecl)
4415  VarTemplate->AddSpecialization(Specialization, InsertPos);
4416  }
4417 
4418  // C++ [temp.expl.spec]p6:
4419  // If a template, a member template or the member of a class template is
4420  // explicitly specialized then that specialization shall be declared
4421  // before the first use of that specialization that would cause an implicit
4422  // instantiation to take place, in every translation unit in which such a
4423  // use occurs; no diagnostic is required.
4424  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
4425  bool Okay = false;
4426  for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
4427  // Is there any previous explicit specialization declaration?
4429  Okay = true;
4430  break;
4431  }
4432  }
4433 
4434  if (!Okay) {
4435  SourceRange Range(TemplateNameLoc, RAngleLoc);
4436  Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
4437  << Name << Range;
4438 
4439  Diag(PrevDecl->getPointOfInstantiation(),
4440  diag::note_instantiation_required_here)
4441  << (PrevDecl->getTemplateSpecializationKind() !=
4443  return true;
4444  }
4445  }
4446 
4447  Specialization->setTemplateKeywordLoc(TemplateKWLoc);
4448  Specialization->setLexicalDeclContext(CurContext);
4449 
4450  // Add the specialization into its lexical context, so that it can
4451  // be seen when iterating through the list of declarations in that
4452  // context. However, specializations are not found by name lookup.
4453  CurContext->addDecl(Specialization);
4454 
4455  // Note that this is an explicit specialization.
4456  Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
4457 
4458  if (PrevDecl) {
4459  // Check that this isn't a redefinition of this specialization,
4460  // merging with previous declarations.
4461  LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
4462  forRedeclarationInCurContext());
4463  PrevSpec.addDecl(PrevDecl);
4464  D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
4465  } else if (Specialization->isStaticDataMember() &&
4466  Specialization->isOutOfLine()) {
4467  Specialization->setAccess(VarTemplate->getAccess());
4468  }
4469 
4470  return Specialization;
4471 }
4472 
4473 namespace {
4474 /// A partial specialization whose template arguments have matched
4475 /// a given template-id.
4476 struct PartialSpecMatchResult {
4478  TemplateArgumentList *Args;
4479 };
4480 } // end anonymous namespace
4481 
4482 DeclResult
4484  SourceLocation TemplateNameLoc,
4485  const TemplateArgumentListInfo &TemplateArgs) {
4486  assert(Template && "A variable template id without template?");
4487 
4488  // Check that the template argument list is well-formed for this template.
4490  if (CheckTemplateArgumentList(
4491  Template, TemplateNameLoc,
4492  const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
4493  Converted, /*UpdateArgsWithConversion=*/true))
4494  return true;
4495 
4496  // Produce a placeholder value if the specialization is dependent.
4497  if (Template->getDeclContext()->isDependentContext() ||
4499  Converted))
4500  return DeclResult();
4501 
4502  // Find the variable template specialization declaration that
4503  // corresponds to these arguments.
4504  void *InsertPos = nullptr;
4505  if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
4506  Converted, InsertPos)) {
4507  checkSpecializationVisibility(TemplateNameLoc, Spec);
4508  // If we already have a variable template specialization, return it.
4509  return Spec;
4510  }
4511 
4512  // This is the first time we have referenced this variable template
4513  // specialization. Create the canonical declaration and add it to
4514  // the set of specializations, based on the closest partial specialization
4515  // that it represents. That is,
4516  VarDecl *InstantiationPattern = Template->getTemplatedDecl();
4518  Converted);
4519  TemplateArgumentList *InstantiationArgs = &TemplateArgList;
4520  bool AmbiguousPartialSpec = false;
4521  typedef PartialSpecMatchResult MatchResult;
4523  SourceLocation PointOfInstantiation = TemplateNameLoc;
4524  TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
4525  /*ForTakingAddress=*/false);
4526 
4527  // 1. Attempt to find the closest partial specialization that this
4528  // specializes, if any.
4529  // TODO: Unify with InstantiateClassTemplateSpecialization()?
4530  // Perhaps better after unification of DeduceTemplateArguments() and
4531  // getMoreSpecializedPartialSpecialization().
4533  Template->getPartialSpecializations(PartialSpecs);
4534 
4535  for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
4536  VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
4537  TemplateDeductionInfo Info(FailedCandidates.getLocation());
4538 
4539  if (TemplateDeductionResult Result =
4540  DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
4541  // Store the failed-deduction information for use in diagnostics, later.
4542  // TODO: Actually use the failed-deduction info?
4543  FailedCandidates.addCandidate().set(
4544  DeclAccessPair::make(Template, AS_public), Partial,
4545  MakeDeductionFailureInfo(Context, Result, Info));
4546  (void)Result;
4547  } else {
4548  Matched.push_back(PartialSpecMatchResult());
4549  Matched.back().Partial = Partial;
4550  Matched.back().Args = Info.take();
4551  }
4552  }
4553 
4554  if (Matched.size() >= 1) {
4555  SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
4556  if (Matched.size() == 1) {
4557  // -- If exactly one matching specialization is found, the
4558  // instantiation is generated from that specialization.
4559  // We don't need to do anything for this.
4560  } else {
4561  // -- If more than one matching specialization is found, the
4562  // partial order rules (14.5.4.2) are used to determine
4563  // whether one of the specializations is more specialized
4564  // than the others. If none of the specializations is more
4565  // specialized than all of the other matching
4566  // specializations, then the use of the variable template is
4567  // ambiguous and the program is ill-formed.
4568  for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
4569  PEnd = Matched.end();
4570  P != PEnd; ++P) {
4571  if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
4572  PointOfInstantiation) ==
4573  P->Partial)
4574  Best = P;
4575  }
4576 
4577  // Determine if the best partial specialization is more specialized than
4578  // the others.
4579  for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
4580  PEnd = Matched.end();
4581  P != PEnd; ++P) {
4582  if (P != Best && getMoreSpecializedPartialSpecialization(
4583  P->Partial, Best->Partial,
4584  PointOfInstantiation) != Best->Partial) {
4585  AmbiguousPartialSpec = true;
4586  break;
4587  }
4588  }
4589  }
4590 
4591  // Instantiate using the best variable template partial specialization.
4592  InstantiationPattern = Best->Partial;
4593  InstantiationArgs = Best->Args;
4594  } else {
4595  // -- If no match is found, the instantiation is generated
4596  // from the primary template.
4597  // InstantiationPattern = Template->getTemplatedDecl();
4598  }
4599 
4600  // 2. Create the canonical declaration.
4601  // Note that we do not instantiate a definition until we see an odr-use
4602  // in DoMarkVarDeclReferenced().
4603  // FIXME: LateAttrs et al.?
4604  VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
4605  Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
4606  Converted, TemplateNameLoc /*, LateAttrs, StartingScope*/);
4607  if (!Decl)
4608  return true;
4609 
4610  if (AmbiguousPartialSpec) {
4611  // Partial ordering did not produce a clear winner. Complain.
4612  Decl->setInvalidDecl();
4613  Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
4614  << Decl;
4615 
4616  // Print the matching partial specializations.
4617  for (MatchResult P : Matched)
4618  Diag(P.Partial->getLocation(), diag::note_partial_spec_match)
4619  << getTemplateArgumentBindingsText(P.Partial->getTemplateParameters(),
4620  *P.Args);
4621  return true;
4622  }
4623 
4625  dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
4626  Decl->setInstantiationOf(D, InstantiationArgs);
4627 
4628  checkSpecializationVisibility(TemplateNameLoc, Decl);
4629 
4630  assert(Decl && "No variable template specialization?");
4631  return Decl;
4632 }
4633 
4634 ExprResult
4636  const DeclarationNameInfo &NameInfo,
4637  VarTemplateDecl *Template, SourceLocation TemplateLoc,
4638  const TemplateArgumentListInfo *TemplateArgs) {
4639 
4640  DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
4641  *TemplateArgs);
4642  if (Decl.isInvalid())
4643  return ExprError();
4644 
4645  if (!Decl.get())
4646  return ExprResult();
4647 
4648  VarDecl *Var = cast<VarDecl>(Decl.get());
4649  if (!Var->getTemplateSpecializationKind())
4651  NameInfo.getLoc());
4652 
4653  // Build an ordinary singleton decl ref.
4654  return BuildDeclarationNameExpr(SS, NameInfo, Var,
4655  /*FoundD=*/nullptr, TemplateArgs);
4656 }
4657 
4659  SourceLocation Loc) {
4660  Diag(Loc, diag::err_template_missing_args)
4661  << (int)getTemplateNameKindForDiagnostics(Name) << Name;
4662  if (TemplateDecl *TD = Name.getAsTemplateDecl()) {
4663  Diag(TD->getLocation(), diag::note_template_decl_here)
4664  << TD->getTemplateParameters()->getSourceRange();
4665  }
4666 }
4667 
4668 ExprResult
4670  SourceLocation TemplateKWLoc,
4671  const DeclarationNameInfo &ConceptNameInfo,
4672  NamedDecl *FoundDecl,
4673  ConceptDecl *NamedConcept,
4674  const TemplateArgumentListInfo *TemplateArgs) {
4675  assert(NamedConcept && "A concept template id without a template?");
4676 
4678  if (CheckTemplateArgumentList(NamedConcept, ConceptNameInfo.getLoc(),
4679  const_cast<TemplateArgumentListInfo&>(*TemplateArgs),
4680  /*PartialTemplateArgs=*/false, Converted,
4681  /*UpdateArgsWithConversion=*/false))
4682  return ExprError();
4683 
4684  ConstraintSatisfaction Satisfaction;
4685  bool AreArgsDependent =
4687  Converted);
4688  if (!AreArgsDependent &&
4690  NamedConcept, {NamedConcept->getConstraintExpr()}, Converted,
4691  SourceRange(SS.isSet() ? SS.getBeginLoc() : ConceptNameInfo.getLoc(),
4692  TemplateArgs->getRAngleLoc()),
4693  Satisfaction))
4694  return ExprError();
4695 
4696  return ConceptSpecializationExpr::Create(Context,
4697  SS.isSet() ? SS.getWithLocInContext(Context) : NestedNameSpecifierLoc{},
4698  TemplateKWLoc, ConceptNameInfo, FoundDecl, NamedConcept,
4699  ASTTemplateArgumentListInfo::Create(Context, *TemplateArgs), Converted,
4700  AreArgsDependent ? nullptr : &Satisfaction);
4701 }
4702 
4704  SourceLocation TemplateKWLoc,
4705  LookupResult &R,
4706  bool RequiresADL,
4707  const TemplateArgumentListInfo *TemplateArgs) {
4708  // FIXME: Can we do any checking at this point? I guess we could check the
4709  // template arguments that we have against the template name, if the template
4710  // name refers to a single template. That's not a terribly common case,
4711  // though.
4712  // foo<int> could identify a single function unambiguously
4713  // This approach does NOT work, since f<int>(1);
4714  // gets resolved prior to resorting to overload resolution
4715  // i.e., template<class T> void f(double);
4716  // vs template<class T, class U> void f(U);
4717 
4718  // These should be filtered out by our callers.
4719  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
4720 
4721  // Non-function templates require a template argument list.
4722  if (auto *TD = R.getAsSingle<TemplateDecl>()) {
4723  if (!TemplateArgs && !isa<FunctionTemplateDecl>(TD)) {
4724  diagnoseMissingTemplateArguments(TemplateName(TD), R.getNameLoc());
4725  return ExprError();
4726  }
4727  }
4728 
4729  // In C++1y, check variable template ids.
4730  if (R.getAsSingle<VarTemplateDecl>()) {
4731  ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
4733  TemplateKWLoc, TemplateArgs);
4734  if (Res.isInvalid() || Res.isUsable())
4735  return Res;
4736  // Result is dependent. Carry on to build an UnresolvedLookupEpxr.
4737  }
4738 
4739  if (R.getAsSingle<ConceptDecl>()) {
4740  return CheckConceptTemplateId(SS, TemplateKWLoc, R.getLookupNameInfo(),
4741  R.getFoundDecl(),
4742  R.getAsSingle<ConceptDecl>(), TemplateArgs);
4743  }
4744 
4745  // We don't want lookup warnings at this point.
4746  R.suppressDiagnostics();
4747 
4750  SS.getWithLocInContext(Context),
4751  TemplateKWLoc,
4752  R.getLookupNameInfo(),
4753  RequiresADL, TemplateArgs,
4754  R.begin(), R.end());
4755 
4756  return ULE;
4757 }
4758 
4759 // We actually only call this from template instantiation.
4760 ExprResult
4762  SourceLocation TemplateKWLoc,
4763  const DeclarationNameInfo &NameInfo,
4764  const TemplateArgumentListInfo *TemplateArgs) {
4765 
4766  assert(TemplateArgs || TemplateKWLoc.isValid());
4767  DeclContext *DC;
4768  if (!(DC = computeDeclContext(SS, false)) ||
4769  DC->isDependentContext() ||
4770  RequireCompleteDeclContext(SS, DC))
4771  return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
4772 
4773  bool MemberOfUnknownSpecialization;
4774  LookupResult R(*this, NameInfo, LookupOrdinaryName);
4775  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
4776  /*Entering*/false, MemberOfUnknownSpecialization,
4777  TemplateKWLoc))
4778  return ExprError();
4779 
4780  if (R.isAmbiguous())
4781  return ExprError();
4782 
4783  if (R.empty()) {
4784  Diag(NameInfo.getLoc(), diag::err_no_member)
4785  << NameInfo.getName() << DC << SS.getRange();
4786  return ExprError();
4787  }
4788 
4789  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
4790  Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
4791  << SS.getScopeRep()
4792  << NameInfo.getName().getAsString() << SS.getRange();
4793  Diag(Temp->getLocation(), diag::note_referenced_class_template);
4794  return ExprError();
4795  }
4796 
4797  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
4798 }
4799 
4800 /// Form a template name from a name that is syntactically required to name a
4801 /// template, either due to use of the 'template' keyword or because a name in
4802 /// this syntactic context is assumed to name a template (C++ [temp.names]p2-4).
4803 ///
4804 /// This action forms a template name given the name of the template and its
4805 /// optional scope specifier. This is used when the 'template' keyword is used
4806 /// or when the parsing context unambiguously treats a following '<' as
4807 /// introducing a template argument list. Note that this may produce a
4808 /// non-dependent template name if we can perform the lookup now and identify
4809 /// the named template.
4810 ///
4811 /// For example, given "x.MetaFun::template apply", the scope specifier
4812 /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
4813 /// of the "template" keyword, and "apply" is the \p Name.
4815  CXXScopeSpec &SS,
4816  SourceLocation TemplateKWLoc,
4817  const UnqualifiedId &Name,
4818  ParsedType ObjectType,
4819  bool EnteringContext,
4820  TemplateTy &Result,
4821  bool AllowInjectedClassName) {
4822  if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
4823  Diag(TemplateKWLoc,
4824  getLangOpts().CPlusPlus11 ?
4825  diag::warn_cxx98_compat_template_outside_of_template :
4826  diag::ext_template_outside_of_template)
4827  << FixItHint::CreateRemoval(TemplateKWLoc);
4828 
4829  if (SS.isInvalid())
4830  return TNK_Non_template;
4831 
4832  // Figure out where isTemplateName is going to look.
4833  DeclContext *LookupCtx = nullptr;
4834  if (SS.isNotEmpty())
4835  LookupCtx = computeDeclContext(SS, EnteringContext);
4836  else if (ObjectType)
4837  LookupCtx = computeDeclContext(GetTypeFromParser(ObjectType));
4838 
4839  // C++0x [temp.names]p5:
4840  // If a name prefixed by the keyword template is not the name of
4841  // a template, the program is ill-formed. [Note: the keyword
4842  // template may not be applied to non-template members of class
4843  // templates. -end note ] [ Note: as is the case with the
4844  // typename prefix, the template prefix is allowed in cases
4845  // where it is not strictly necessary; i.e., when the
4846  // nested-name-specifier or the expression on the left of the ->
4847  // or . is not dependent on a template-parameter, or the use
4848  // does not appear in the scope of a template. -end note]
4849  //
4850  // Note: C++03 was more strict here, because it banned the use of
4851  // the "template" keyword prior to a template-name that was not a
4852  // dependent name. C++ DR468 relaxed this requirement (the
4853  // "template" keyword is now permitted). We follow the C++0x
4854  // rules, even in C++03 mode with a warning, retroactively applying the DR.
4855  bool MemberOfUnknownSpecialization;
4856  TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
4857  ObjectType, EnteringContext, Result,
4858  MemberOfUnknownSpecialization);
4859  if (TNK != TNK_Non_template) {
4860  // We resolved this to a (non-dependent) template name. Return it.
4861  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
4862  if (!AllowInjectedClassName && SS.isNotEmpty() && LookupRD &&
4863  Name.getKind() == UnqualifiedIdKind::IK_Identifier &&
4864  Name.Identifier && LookupRD->getIdentifier() == Name.Identifier) {
4865  // C++14 [class.qual]p2:
4866  // In a lookup in which function names are not ignored and the
4867  // nested-name-specifier nominates a class C, if the name specified
4868  // [...] is the injected-class-name of C, [...] the name is instead
4869  // considered to name the constructor
4870  //
4871  // We don't get here if naming the constructor would be valid, so we
4872  // just reject immediately and recover by treating the
4873  // injected-class-name as naming the template.
4874  Diag(Name.getBeginLoc(),
4875  diag::ext_out_of_line_qualified_id_type_names_constructor)
4876  << Name.Identifier
4877  << 0 /*injected-class-name used as template name*/
4878  << TemplateKWLoc.isValid();
4879  }
4880  return TNK;
4881  }
4882 
4883  if (!MemberOfUnknownSpecialization) {
4884  // Didn't find a template name, and the lookup wasn't dependent.
4885  // Do the lookup again to determine if this is a "nothing found" case or
4886  // a "not a template" case. FIXME: Refactor isTemplateName so we don't
4887  // need to do this.
4888  DeclarationNameInfo DNI = GetNameFromUnqualifiedId(Name);
4889  LookupResult R(*this, DNI.getName(), Name.getBeginLoc(),
4890  LookupOrdinaryName);
4891  bool MOUS;
4892  // Tell LookupTemplateName that we require a template so that it diagnoses
4893  // cases where it finds a non-template.
4894  RequiredTemplateKind RTK = TemplateKWLoc.isValid()
4895  ? RequiredTemplateKind(TemplateKWLoc)
4896  : TemplateNameIsRequired;
4897  if (!LookupTemplateName(R, S, SS, ObjectType.get(), EnteringContext, MOUS,
4898  RTK, nullptr, /*AllowTypoCorrection=*/false) &&
4899  !R.isAmbiguous()) {
4900  if (LookupCtx)
4901  Diag(Name.getBeginLoc(), diag::err_no_member)
4902  << DNI.getName() << LookupCtx << SS.getRange();
4903  else
4904  Diag(Name.getBeginLoc(), diag::err_undeclared_use)
4905  << DNI.getName() << SS.getRange();
4906  }
4907  return TNK_Non_template;
4908  }
4909 
4910  NestedNameSpecifier *Qualifier = SS.getScopeRep();
4911 
4912  switch (Name.getKind()) {
4914  Result = TemplateTy::make(
4915  Context.getDependentTemplateName(Qualifier, Name.Identifier));
4917 
4919  Result = TemplateTy::make(Context.getDependentTemplateName(
4920  Qualifier, Name.OperatorFunctionId.Operator));
4921  return TNK_Function_template;
4922 
4924  // This is a kind of template name, but can never occur in a dependent
4925  // scope (literal operators can only be declared at namespace scope).
4926  break;
4927 
4928  default:
4929  break;
4930  }
4931 
4932  // This name cannot possibly name a dependent template. Diagnose this now
4933  // rather than building a dependent template name that can never be valid.
4934  Diag(Name.getBeginLoc(),
4935  diag::err_template_kw_refers_to_dependent_non_template)
4936  << GetNameFromUnqualifiedId(Name).getName() << Name.getSourceRange()
4937  << TemplateKWLoc.isValid() << TemplateKWLoc;
4938  return TNK_Non_template;
4939 }
4940 
4942  TemplateArgumentLoc &AL,
4943  SmallVectorImpl<TemplateArgument> &Converted) {
4944  const TemplateArgument &Arg = AL.getArgument();
4945  QualType ArgType;
4946  TypeSourceInfo *TSI = nullptr;
4947 
4948  // Check template type parameter.
4949  switch(Arg.getKind()) {
4951  // C++ [temp.arg.type]p1:
4952  // A template-argument for a template-parameter which is a
4953  // type shall be a type-id.
4954  ArgType = Arg.getAsType();
4955  TSI = AL.getTypeSourceInfo();
4956  break;
4959  // We have a template type parameter but the template argument
4960  // is a template without any arguments.
4961  SourceRange SR = AL.getSourceRange();
4963  diagnoseMissingTemplateArguments(Name, SR.getEnd());
4964  return true;
4965  }
4967  // We have a template type parameter but the template argument is an
4968  // expression; see if maybe it is missing the "typename" keyword.
4969  CXXScopeSpec SS;
4970  DeclarationNameInfo NameInfo;
4971 
4972  if (DependentScopeDeclRefExpr *ArgExpr =
4973  dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
4974  SS.Adopt(ArgExpr->getQualifierLoc());
4975  NameInfo = ArgExpr->getNameInfo();
4976  } else if (CXXDependentScopeMemberExpr *ArgExpr =
4977  dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
4978  if (ArgExpr->isImplicitAccess()) {
4979  SS.Adopt(ArgExpr->getQualifierLoc());
4980  NameInfo = ArgExpr->getMemberNameInfo();
4981  }
4982  }
4983 
4984  if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
4985  LookupResult Result(*this, NameInfo, LookupOrdinaryName);
4986  LookupParsedName(Result, CurScope, &SS);
4987 
4988  if (Result.getAsSingle<TypeDecl>() ||
4989  Result.getResultKind() ==
4991  assert(SS.getScopeRep() && "dependent scope expr must has a scope!");
4992  // Suggest that the user add 'typename' before the NNS.
4993  SourceLocation Loc = AL.getSourceRange().getBegin();
4994  Diag(Loc, getLangOpts().MSVCCompat
4995  ? diag::ext_ms_template_type_arg_missing_typename
4996  : diag::err_template_arg_must_be_type_suggest)
4997  << FixItHint::CreateInsertion(Loc, "typename ");
4998  Diag(Param->getLocation(), diag::note_template_param_here);
4999 
5000  // Recover by synthesizing a type using the location information that we
5001  // already have.
5002  ArgType =
5003  Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
5004  TypeLocBuilder TLB;
5005  DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
5006  TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
5007  TL.setQualifierLoc(SS.getWithLocInContext(Context));
5008  TL.setNameLoc(NameInfo.getLoc());
5009  TSI = TLB.getTypeSourceInfo(Context, ArgType);
5010 
5011  // Overwrite our input TemplateArgumentLoc so that we can recover
5012  // properly.
5013  AL = TemplateArgumentLoc(TemplateArgument(ArgType),
5015 
5016  break;
5017  }
5018  }
5019  // fallthrough
5020  LLVM_FALLTHROUGH;
5021  }
5022  default: {
5023  // We have a template type parameter but the template argument
5024  // is not a type.
5025  SourceRange SR = AL.getSourceRange();
5026  Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
5027  Diag(Param->getLocation(), diag::note_template_param_here);
5028 
5029  return true;
5030  }
5031  }
5032 
5033  if (CheckTemplateArgument(TSI))
5034  return true;
5035 
5036  // Add the converted template type argument.
5037  ArgType = Context.getCanonicalType(ArgType);
5038 
5039  // Objective-C ARC:
5040  // If an explicitly-specified template argument type is a lifetime type
5041  // with no lifetime qualifier, the __strong lifetime qualifier is inferred.
5042  if (getLangOpts().ObjCAutoRefCount &&
5043  ArgType->isObjCLifetimeType() &&
5044  !ArgType.getObjCLifetime()) {
5045  Qualifiers Qs;
5047  ArgType = Context.getQualifiedType(ArgType, Qs);
5048  }
5049 
5050  Converted.push_back(TemplateArgument(ArgType));
5051  return false;
5052 }
5053 
5054 /// Substitute template arguments into the default template argument for
5055 /// the given template type parameter.
5056 ///
5057 /// \param SemaRef the semantic analysis object for which we are performing
5058 /// the substitution.
5059 ///
5060 /// \param Template the template that we are synthesizing template arguments
5061 /// for.
5062 ///
5063 /// \param TemplateLoc the location of the template name that started the
5064 /// template-id we are checking.
5065 ///
5066 /// \param RAngleLoc the location of the right angle bracket ('>') that
5067 /// terminates the template-id.
5068 ///
5069 /// \param Param the template template parameter whose default we are
5070 /// substituting into.
5071 ///
5072 /// \param Converted the list of template arguments provided for template
5073 /// parameters that precede \p Param in the template parameter list.
5074 /// \returns the substituted template argument, or NULL if an error occurred.
5075 static TypeSourceInfo *
5077  TemplateDecl *Template,
5078  SourceLocation TemplateLoc,
5079  SourceLocation RAngleLoc,
5080  TemplateTypeParmDecl *Param,
5081  SmallVectorImpl<TemplateArgument> &Converted) {
5082  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
5083 
5084  // If the argument type is dependent, instantiate it now based
5085  // on the previously-computed template arguments.
5086  if (ArgType->getType()->isInstantiationDependentType()) {
5087  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5088  Param, Template, Converted,
5089  SourceRange(TemplateLoc, RAngleLoc));
5090  if (Inst.isInvalid())
5091  return nullptr;
5092 
5093  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5094 
5095  // Only substitute for the innermost template argument list.
5096  MultiLevelTemplateArgumentList TemplateArgLists;
5097  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5098  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5099  TemplateArgLists.addOuterTemplateArguments(None);
5100 
5101  bool ForLambdaCallOperator = false;
5102  if (const auto *Rec = dyn_cast<CXXRecordDecl>(Template->getDeclContext()))
5103  ForLambdaCallOperator = Rec->isLambda();
5104  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext(),
5105  !ForLambdaCallOperator);
5106  ArgType =
5107  SemaRef.SubstType(ArgType, TemplateArgLists,
5108  Param->getDefaultArgumentLoc(), Param->getDeclName());
5109  }
5110 
5111  return ArgType;
5112 }
5113 
5114 /// Substitute template arguments into the default template argument for
5115 /// the given non-type template parameter.
5116 ///
5117 /// \param SemaRef the semantic analysis object for which we are performing
5118 /// the substitution.
5119 ///
5120 /// \param Template the template that we are synthesizing template arguments
5121 /// for.
5122 ///
5123 /// \param TemplateLoc the location of the template name that started the
5124 /// template-id we are checking.
5125 ///
5126 /// \param RAngleLoc the location of the right angle bracket ('>') that
5127 /// terminates the template-id.
5128 ///
5129 /// \param Param the non-type template parameter whose default we are
5130 /// substituting into.
5131 ///
5132 /// \param Converted the list of template arguments provided for template
5133 /// parameters that precede \p Param in the template parameter list.
5134 ///
5135 /// \returns the substituted template argument, or NULL if an error occurred.
5136 static ExprResult
5138  TemplateDecl *Template,
5139  SourceLocation TemplateLoc,
5140  SourceLocation RAngleLoc,
5141  NonTypeTemplateParmDecl *Param,
5142  SmallVectorImpl<TemplateArgument> &Converted) {
5143  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
5144  Param, Template, Converted,
5145  SourceRange(TemplateLoc, RAngleLoc));
5146  if (Inst.isInvalid())
5147  return ExprError();
5148 
5149  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5150 
5151  // Only substitute for the innermost template argument list.
5152  MultiLevelTemplateArgumentList TemplateArgLists;
5153  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5154  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5155  TemplateArgLists.addOuterTemplateArguments(None);
5156 
5157  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5158  EnterExpressionEvaluationContext ConstantEvaluated(
5160  return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
5161 }
5162 
5163 /// Substitute template arguments into the default template argument for
5164 /// the given template template parameter.
5165 ///
5166 /// \param SemaRef the semantic analysis object for which we are performing
5167 /// the substitution.
5168 ///
5169 /// \param Template the template that we are synthesizing template arguments
5170 /// for.
5171 ///
5172 /// \param TemplateLoc the location of the template name that started the
5173 /// template-id we are checking.
5174 ///
5175 /// \param RAngleLoc the location of the right angle bracket ('>') that
5176 /// terminates the template-id.
5177 ///
5178 /// \param Param the template template parameter whose default we are
5179 /// substituting into.
5180 ///
5181 /// \param Converted the list of template arguments provided for template
5182 /// parameters that precede \p Param in the template parameter list.
5183 ///
5184 /// \param QualifierLoc Will be set to the nested-name-specifier (with
5185 /// source-location information) that precedes the template name.
5186 ///
5187 /// \returns the substituted template argument, or NULL if an error occurred.
5188 static TemplateName
5190  TemplateDecl *Template,
5191  SourceLocation TemplateLoc,
5192  SourceLocation RAngleLoc,
5193  TemplateTemplateParmDecl *Param,
5195  NestedNameSpecifierLoc &QualifierLoc) {
5197  SemaRef, TemplateLoc, TemplateParameter(Param), Template, Converted,
5198  SourceRange(TemplateLoc, RAngleLoc));
5199  if (Inst.isInvalid())
5200  return TemplateName();
5201 
5202  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5203 
5204  // Only substitute for the innermost template argument list.
5205  MultiLevelTemplateArgumentList TemplateArgLists;
5206  TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
5207  for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
5208  TemplateArgLists.addOuterTemplateArguments(None);
5209 
5210  Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
5211  // Substitute into the nested-name-specifier first,
5212  QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
5213  if (QualifierLoc) {
5214  QualifierLoc =
5215  SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
5216  if (!QualifierLoc)
5217  return TemplateName();
5218  }
5219 
5220  return SemaRef.SubstTemplateName(
5221  QualifierLoc,
5224  TemplateArgLists);
5225 }
5226 
5227 /// If the given template parameter has a default template
5228 /// argument, substitute into that default template argument and
5229 /// return the corresponding template argument.
5232  SourceLocation TemplateLoc,
5233  SourceLocation RAngleLoc,
5234  Decl *Param,
5236  &Converted,
5237  bool &HasDefaultArg) {
5238  HasDefaultArg = false;
5239 
5240  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
5241  if (!hasVisibleDefaultArgument(TypeParm))
5242  return TemplateArgumentLoc();
5243 
5244  HasDefaultArg = true;
5245  TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
5246  TemplateLoc,
5247  RAngleLoc,
5248  TypeParm,
5249  Converted);
5250  if (DI)
5251  return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
5252 
5253  return TemplateArgumentLoc();
5254  }
5255 
5256  if (NonTypeTemplateParmDecl *NonTypeParm
5257  = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5258  if (!hasVisibleDefaultArgument(NonTypeParm))
5259  return TemplateArgumentLoc();
5260 
5261  HasDefaultArg = true;
5262  ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
5263  TemplateLoc,
5264  RAngleLoc,
5265  NonTypeParm,
5266  Converted);
5267  if (Arg.isInvalid())
5268  return TemplateArgumentLoc();
5269 
5270  Expr *ArgE = Arg.getAs<Expr>();
5271  return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
5272  }
5273 
5274  TemplateTemplateParmDecl *TempTempParm
5275  = cast<TemplateTemplateParmDecl>(Param);
5276  if (!hasVisibleDefaultArgument(TempTempParm))
5277  return TemplateArgumentLoc();
5278 
5279  HasDefaultArg = true;
5280  NestedNameSpecifierLoc QualifierLoc;
5281  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
5282  TemplateLoc,
5283  RAngleLoc,
5284  TempTempParm,
5285  Converted,
5286  QualifierLoc);
5287  if (TName.isNull())
5288  return TemplateArgumentLoc();
5289 
5290  return TemplateArgumentLoc(
5291  Context, TemplateArgument(TName),
5292  TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
5293  TempTempParm->getDefaultArgument().getTemplateNameLoc());
5294 }
5295 
5296 /// Convert a template-argument that we parsed as a type into a template, if
5297 /// possible. C++ permits injected-class-names to perform dual service as
5298 /// template template arguments and as template type arguments.
5299 static TemplateArgumentLoc
5301  // Extract and step over any surrounding nested-name-specifier.
5302  NestedNameSpecifierLoc QualLoc;
5303  if (auto ETLoc = TLoc.getAs<ElaboratedTypeLoc>()) {
5304  if (ETLoc.getTypePtr()->getKeyword() != ETK_None)
5305  return TemplateArgumentLoc();
5306 
5307  QualLoc = ETLoc.getQualifierLoc();
5308  TLoc = ETLoc.getNamedTypeLoc();
5309  }
5310  // If this type was written as an injected-class-name, it can be used as a
5311  // template template argument.
5312  if (auto InjLoc = TLoc.getAs<InjectedClassNameTypeLoc>())
5313  return TemplateArgumentLoc(Context, InjLoc.getTypePtr()->getTemplateName(),
5314  QualLoc, InjLoc.getNameLoc());
5315 
5316  // If this type was written as an injected-class-name, it may have been
5317  // converted to a RecordType during instantiation. If the RecordType is
5318  // *not* wrapped in a TemplateSpecializationType and denotes a class
5319  // template specialization, it must have come from an injected-class-name.
5320  if (auto RecLoc = TLoc.getAs<RecordTypeLoc>())
5321  if (auto *CTSD =
5322  dyn_cast<ClassTemplateSpecializationDecl>(RecLoc.getDecl()))
5323  return TemplateArgumentLoc(Context,
5324  TemplateName(CTSD->getSpecializedTemplate()),
5325  QualLoc, RecLoc.getNameLoc());
5326 
5327  return TemplateArgumentLoc();
5328 }
5329 
5330 /// Check that the given template argument corresponds to the given
5331 /// template parameter.
5332 ///
5333 /// \param Param The template parameter against which the argument will be
5334 /// checked.
5335 ///
5336 /// \param Arg The template argument, which may be updated due to conversions.
5337 ///
5338 /// \param Template The template in which the template argument resides.
5339 ///
5340 /// \param TemplateLoc The location of the template name for the template
5341 /// whose argument list we're matching.
5342 ///
5343 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
5344 /// the template argument list.
5345 ///
5346 /// \param ArgumentPackIndex The index into the argument pack where this
5347 /// argument will be placed. Only valid if the parameter is a parameter pack.
5348 ///
5349 /// \param Converted The checked, converted argument will be added to the
5350 /// end of this small vector.
5351 ///
5352 /// \param CTAK Describes how we arrived at this particular template argument:
5353 /// explicitly written, deduced, etc.
5354 ///
5355 /// \returns true on error, false otherwise.
5357  TemplateArgumentLoc &Arg,
5358  NamedDecl *Template,
5359  SourceLocation TemplateLoc,
5360  SourceLocation RAngleLoc,
5361  unsigned ArgumentPackIndex,
5364  // Check template type parameters.
5365  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
5366  return CheckTemplateTypeArgument(TTP, Arg, Converted);
5367 
5368  // Check non-type template parameters.
5369  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
5370  // Do substitution on the type of the non-type template parameter
5371  // with the template arguments we've seen thus far. But if the
5372  // template has a dependent context then we cannot substitute yet.
5373  QualType NTTPType = NTTP->getType();
5374  if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
5375  NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
5376 
5377  if (NTTPType->isInstantiationDependentType() &&
5378  !isa<TemplateTemplateParmDecl>(Template) &&
5379  !Template->getDeclContext()->isDependentContext()) {
5380  // Do substitution on the type of the non-type template parameter.
5381  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5382  NTTP, Converted,
5383  SourceRange(TemplateLoc, RAngleLoc));
5384  if (Inst.isInvalid())
5385  return true;
5386 
5388  Converted);
5389 
5390  // If the parameter is a pack expansion, expand this slice of the pack.
5391  if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
5392  Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
5393  ArgumentPackIndex);
5394  NTTPType = SubstType(PET->getPattern(),
5395  MultiLevelTemplateArgumentList(TemplateArgs),
5396  NTTP->getLocation(),
5397  NTTP->getDeclName());
5398  } else {
5399  NTTPType = SubstType(NTTPType,
5400  MultiLevelTemplateArgumentList(TemplateArgs),
5401  NTTP->getLocation(),
5402  NTTP->getDeclName());
5403  }
5404 
5405  // If that worked, check the non-type template parameter type
5406  // for validity.
5407  if (!NTTPType.isNull())
5408  NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
5409  NTTP->getLocation());
5410  if (NTTPType.isNull())
5411  return true;
5412  }
5413 
5414  switch (Arg.getArgument().getKind()) {
5416  llvm_unreachable("Should never see a NULL template argument here");
5417 
5419  TemplateArgument Result;
5420  unsigned CurSFINAEErrors = NumSFINAEErrors;
5421  ExprResult Res =
5422  CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
5423  Result, CTAK);
5424  if (Res.isInvalid())
5425  return true;
5426  // If the current template argument causes an error, give up now.
5427  if (CurSFINAEErrors < NumSFINAEErrors)
5428  return true;
5429 
5430  // If the resulting expression is new, then use it in place of the
5431  // old expression in the template argument.
5432  if (Res.get() != Arg.getArgument().getAsExpr()) {
5433  TemplateArgument TA(Res.get());
5434  Arg = TemplateArgumentLoc(TA, Res.get());
5435  }
5436 
5437  Converted.push_back(Result);
5438  break;
5439  }
5440 
5444  // We've already checked this template argument, so just copy
5445  // it to the list of converted arguments.
5446  Converted.push_back(Arg.getArgument());
5447  break;
5448 
5451  // We were given a template template argument. It may not be ill-formed;
5452  // see below.
5453  if (DependentTemplateName *DTN
5456  // We have a template argument such as \c T::template X, which we
5457  // parsed as a template template argument. However, since we now
5458  // know that we need a non-type template argument, convert this
5459  // template name into an expression.
5460 
5461  DeclarationNameInfo NameInfo(DTN->getIdentifier(),
5462  Arg.getTemplateNameLoc());
5463 
5464  CXXScopeSpec SS;
5465  SS.Adopt(Arg.getTemplateQualifierLoc());
5466  // FIXME: the template-template arg was a DependentTemplateName,
5467  // so it was provided with a template keyword. However, its source
5468  // location is not stored in the template argument structure.
5469  SourceLocation TemplateKWLoc;
5471  Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
5472  nullptr);
5473 
5474  // If we parsed the template argument as a pack expansion, create a
5475  // pack expansion expression.
5477  E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
5478  if (E.isInvalid())
5479  return true;
5480  }
5481 
5482  TemplateArgument Result;
5483  E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
5484  if (E.isInvalid())
5485  return true;
5486 
5487  Converted.push_back(Result);
5488  break;
5489  }
5490 
5491  // We have a template argument that actually does refer to a class
5492  // template, alias template, or template template parameter, and
5493  // therefore cannot be a non-type template argument.
5494  Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
5495  << Arg.getSourceRange();
5496 
5497  Diag(Param->getLocation(), diag::note_template_param_here);
5498  return true;
5499 
5500  case TemplateArgument::Type: {
5501  // We have a non-type template parameter but the template
5502  // argument is a type.
5503 
5504  // C++ [temp.arg]p2:
5505  // In a template-argument, an ambiguity between a type-id and
5506  // an expression is resolved to a type-id, regardless of the
5507  // form of the corresponding template-parameter.
5508  //
5509  // We warn specifically about this case, since it can be rather
5510  // confusing for users.
5511  QualType T = Arg.getArgument().getAsType();
5512  SourceRange SR = Arg.getSourceRange();
5513  if (T->isFunctionType())
5514  Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
5515  else
5516  Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
5517  Diag(Param->getLocation(), diag::note_template_param_here);
5518  return true;
5519  }
5520 
5522  llvm_unreachable("Caller must expand template argument packs");
5523  }
5524 
5525  return false;
5526  }
5527 
5528 
5529  // Check template template parameters.
5530  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
5531 
5532  TemplateParameterList *Params = TempParm->getTemplateParameters();
5533  if (TempParm->isExpandedParameterPack())
5534  Params = TempParm->getExpansionTemplateParameters(ArgumentPackIndex);
5535 
5536  // Substitute into the template parameter list of the template
5537  // template parameter, since previously-supplied template arguments
5538  // may appear within the template template parameter.
5539  //
5540  // FIXME: Skip this if the parameters aren't instantiation-dependent.
5541  {
5542  // Set up a template instantiation context.
5544  InstantiatingTemplate Inst(*this, TemplateLoc, Template,
5545  TempParm, Converted,
5546  SourceRange(TemplateLoc, RAngleLoc));
5547  if (Inst.isInvalid())
5548  return true;
5549 
5550  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
5551  Params = SubstTemplateParams(Params, CurContext,
5552  MultiLevelTemplateArgumentList(TemplateArgs));
5553  if (!Params)
5554  return true;
5555  }
5556 
5557  // C++1z [temp.local]p1: (DR1004)
5558  // When [the injected-class-name] is used [...] as a template-argument for
5559  // a template template-parameter [...] it refers to the class template
5560  // itself.
5561  if (Arg.getArgument().getKind() == TemplateArgument::Type) {
5563  Context, Arg.getTypeSourceInfo()->getTypeLoc());
5564  if (!ConvertedArg.getArgument().isNull())
5565  Arg = ConvertedArg;
5566  }
5567 
5568  switch (Arg.getArgument().getKind()) {
5570  llvm_unreachable("Should never see a NULL template argument here");
5571 
5574  if (CheckTemplateTemplateArgument(TempParm, Params, Arg))
5575  return true;
5576 
5577  Converted.push_back(Arg.getArgument());
5578  break;
5579 
5582  // We have a template template parameter but the template
5583  // argument does not refer to a template.
5584  Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
5585  << getLangOpts().CPlusPlus11;
5586  return true;
5587 
5589  llvm_unreachable("Declaration argument with template template parameter");
5591  llvm_unreachable("Integral argument with template template parameter");
5593  llvm_unreachable("Null pointer argument with template template parameter");
5594 
5596  llvm_unreachable("Caller must expand template argument packs");
5597  }
5598 
5599  return false;
5600 }
5601 
5602 /// Diagnose a missing template argument.
5603 template<typename TemplateParmDecl>
5605  TemplateDecl *TD,
5606  const TemplateParmDecl *D,
5607  TemplateArgumentListInfo &Args) {
5608  // Dig out the most recent declaration of the template parameter; there may be
5609  // declarations of the template that are more recent than TD.
5610  D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
5611  ->getTemplateParameters()
5612  ->getParam(D->getIndex()));
5613 
5614  // If there's a default argument that's not visible, diagnose that we're
5615  // missing a module import.
5617  if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
5618  S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
5619  D->getDefaultArgumentLoc(), Modules,
5621  /*Recover*/true);
5622  return true;
5623  }
5624 
5625  // FIXME: If there's a more recent default argument that *is* visible,
5626  // diagnose that it was declared too late.
5627 
5629 
5630  S.Diag(Loc, diag::err_template_arg_list_different_arity)
5631  << /*not enough args*/0
5633  << TD;
5634  S.Diag(TD->getLocation(), diag::note_template_decl_here)
5635  << Params->getSourceRange();
5636  return true;