clang  10.0.0svn
SemaDecl.cpp
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1 //===--- SemaDecl.cpp - Semantic Analysis for Declarations ----------------===//
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 //
9 // This file implements semantic analysis for declarations.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "TypeLocBuilder.h"
14 #include "clang/AST/ASTConsumer.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTLambda.h"
18 #include "clang/AST/CharUnits.h"
20 #include "clang/AST/DeclCXX.h"
21 #include "clang/AST/DeclObjC.h"
22 #include "clang/AST/DeclTemplate.h"
24 #include "clang/AST/ExprCXX.h"
26 #include "clang/AST/StmtCXX.h"
27 #include "clang/Basic/Builtins.h"
30 #include "clang/Basic/TargetInfo.h"
31 #include "clang/Lex/HeaderSearch.h" // TODO: Sema shouldn't depend on Lex
32 #include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
33 #include "clang/Lex/ModuleLoader.h" // TODO: Sema shouldn't depend on Lex
34 #include "clang/Lex/Preprocessor.h" // Included for isCodeCompletionEnabled()
36 #include "clang/Sema/DeclSpec.h"
39 #include "clang/Sema/Lookup.h"
41 #include "clang/Sema/Scope.h"
42 #include "clang/Sema/ScopeInfo.h"
44 #include "clang/Sema/Template.h"
45 #include "llvm/ADT/SmallString.h"
46 #include "llvm/ADT/Triple.h"
47 #include <algorithm>
48 #include <cstring>
49 #include <functional>
50 
51 using namespace clang;
52 using namespace sema;
53 
55  if (OwnedType) {
56  Decl *Group[2] = { OwnedType, Ptr };
57  return DeclGroupPtrTy::make(DeclGroupRef::Create(Context, Group, 2));
58  }
59 
60  return DeclGroupPtrTy::make(DeclGroupRef(Ptr));
61 }
62 
63 namespace {
64 
65 class TypeNameValidatorCCC final : public CorrectionCandidateCallback {
66  public:
67  TypeNameValidatorCCC(bool AllowInvalid, bool WantClass = false,
68  bool AllowTemplates = false,
69  bool AllowNonTemplates = true)
70  : AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
71  AllowTemplates(AllowTemplates), AllowNonTemplates(AllowNonTemplates) {
72  WantExpressionKeywords = false;
73  WantCXXNamedCasts = false;
74  WantRemainingKeywords = false;
75  }
76 
77  bool ValidateCandidate(const TypoCorrection &candidate) override {
78  if (NamedDecl *ND = candidate.getCorrectionDecl()) {
79  if (!AllowInvalidDecl && ND->isInvalidDecl())
80  return false;
81 
82  if (getAsTypeTemplateDecl(ND))
83  return AllowTemplates;
84 
85  bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
86  if (!IsType)
87  return false;
88 
89  if (AllowNonTemplates)
90  return true;
91 
92  // An injected-class-name of a class template (specialization) is valid
93  // as a template or as a non-template.
94  if (AllowTemplates) {
95  auto *RD = dyn_cast<CXXRecordDecl>(ND);
96  if (!RD || !RD->isInjectedClassName())
97  return false;
98  RD = cast<CXXRecordDecl>(RD->getDeclContext());
99  return RD->getDescribedClassTemplate() ||
100  isa<ClassTemplateSpecializationDecl>(RD);
101  }
102 
103  return false;
104  }
105 
106  return !WantClassName && candidate.isKeyword();
107  }
108 
109  std::unique_ptr<CorrectionCandidateCallback> clone() override {
110  return std::make_unique<TypeNameValidatorCCC>(*this);
111  }
112 
113  private:
114  bool AllowInvalidDecl;
115  bool WantClassName;
116  bool AllowTemplates;
117  bool AllowNonTemplates;
118 };
119 
120 } // end anonymous namespace
121 
122 /// Determine whether the token kind starts a simple-type-specifier.
124  switch (Kind) {
125  // FIXME: Take into account the current language when deciding whether a
126  // token kind is a valid type specifier
127  case tok::kw_short:
128  case tok::kw_long:
129  case tok::kw___int64:
130  case tok::kw___int128:
131  case tok::kw_signed:
132  case tok::kw_unsigned:
133  case tok::kw_void:
134  case tok::kw_char:
135  case tok::kw_int:
136  case tok::kw_half:
137  case tok::kw_float:
138  case tok::kw_double:
139  case tok::kw__Float16:
140  case tok::kw___float128:
141  case tok::kw_wchar_t:
142  case tok::kw_bool:
143  case tok::kw___underlying_type:
144  case tok::kw___auto_type:
145  return true;
146 
147  case tok::annot_typename:
148  case tok::kw_char16_t:
149  case tok::kw_char32_t:
150  case tok::kw_typeof:
151  case tok::annot_decltype:
152  case tok::kw_decltype:
153  return getLangOpts().CPlusPlus;
154 
155  case tok::kw_char8_t:
156  return getLangOpts().Char8;
157 
158  default:
159  break;
160  }
161 
162  return false;
163 }
164 
165 namespace {
167  NotFound,
168  FoundNonType,
169  FoundType
170 };
171 } // end anonymous namespace
172 
173 /// Tries to perform unqualified lookup of the type decls in bases for
174 /// dependent class.
175 /// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
176 /// type decl, \a FoundType if only type decls are found.
179  SourceLocation NameLoc,
180  const CXXRecordDecl *RD) {
181  if (!RD->hasDefinition())
182  return UnqualifiedTypeNameLookupResult::NotFound;
183  // Look for type decls in base classes.
184  UnqualifiedTypeNameLookupResult FoundTypeDecl =
185  UnqualifiedTypeNameLookupResult::NotFound;
186  for (const auto &Base : RD->bases()) {
187  const CXXRecordDecl *BaseRD = nullptr;
188  if (auto *BaseTT = Base.getType()->getAs<TagType>())
189  BaseRD = BaseTT->getAsCXXRecordDecl();
190  else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
191  // Look for type decls in dependent base classes that have known primary
192  // templates.
193  if (!TST || !TST->isDependentType())
194  continue;
195  auto *TD = TST->getTemplateName().getAsTemplateDecl();
196  if (!TD)
197  continue;
198  if (auto *BasePrimaryTemplate =
199  dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
200  if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
201  BaseRD = BasePrimaryTemplate;
202  else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
204  CTD->findPartialSpecialization(Base.getType()))
205  if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
206  BaseRD = PS;
207  }
208  }
209  }
210  if (BaseRD) {
211  for (NamedDecl *ND : BaseRD->lookup(&II)) {
212  if (!isa<TypeDecl>(ND))
213  return UnqualifiedTypeNameLookupResult::FoundNonType;
214  FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
215  }
216  if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
217  switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
218  case UnqualifiedTypeNameLookupResult::FoundNonType:
219  return UnqualifiedTypeNameLookupResult::FoundNonType;
220  case UnqualifiedTypeNameLookupResult::FoundType:
221  FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
222  break;
223  case UnqualifiedTypeNameLookupResult::NotFound:
224  break;
225  }
226  }
227  }
228  }
229 
230  return FoundTypeDecl;
231 }
232 
234  const IdentifierInfo &II,
235  SourceLocation NameLoc) {
236  // Lookup in the parent class template context, if any.
237  const CXXRecordDecl *RD = nullptr;
238  UnqualifiedTypeNameLookupResult FoundTypeDecl =
239  UnqualifiedTypeNameLookupResult::NotFound;
240  for (DeclContext *DC = S.CurContext;
241  DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
242  DC = DC->getParent()) {
243  // Look for type decls in dependent base classes that have known primary
244  // templates.
245  RD = dyn_cast<CXXRecordDecl>(DC);
246  if (RD && RD->getDescribedClassTemplate())
247  FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
248  }
249  if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
250  return nullptr;
251 
252  // We found some types in dependent base classes. Recover as if the user
253  // wrote 'typename MyClass::II' instead of 'II'. We'll fully resolve the
254  // lookup during template instantiation.
255  S.Diag(NameLoc, diag::ext_found_via_dependent_bases_lookup) << &II;
256 
257  ASTContext &Context = S.Context;
258  auto *NNS = NestedNameSpecifier::Create(Context, nullptr, false,
259  cast<Type>(Context.getRecordType(RD)));
260  QualType T = Context.getDependentNameType(ETK_Typename, NNS, &II);
261 
262  CXXScopeSpec SS;
263  SS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
264 
265  TypeLocBuilder Builder;
266  DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
267  DepTL.setNameLoc(NameLoc);
269  DepTL.setQualifierLoc(SS.getWithLocInContext(Context));
270  return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
271 }
272 
273 /// If the identifier refers to a type name within this scope,
274 /// return the declaration of that type.
275 ///
276 /// This routine performs ordinary name lookup of the identifier II
277 /// within the given scope, with optional C++ scope specifier SS, to
278 /// determine whether the name refers to a type. If so, returns an
279 /// opaque pointer (actually a QualType) corresponding to that
280 /// type. Otherwise, returns NULL.
282  Scope *S, CXXScopeSpec *SS,
283  bool isClassName, bool HasTrailingDot,
284  ParsedType ObjectTypePtr,
285  bool IsCtorOrDtorName,
286  bool WantNontrivialTypeSourceInfo,
287  bool IsClassTemplateDeductionContext,
288  IdentifierInfo **CorrectedII) {
289  // FIXME: Consider allowing this outside C++1z mode as an extension.
290  bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
291  getLangOpts().CPlusPlus17 && !IsCtorOrDtorName &&
292  !isClassName && !HasTrailingDot;
293 
294  // Determine where we will perform name lookup.
295  DeclContext *LookupCtx = nullptr;
296  if (ObjectTypePtr) {
297  QualType ObjectType = ObjectTypePtr.get();
298  if (ObjectType->isRecordType())
299  LookupCtx = computeDeclContext(ObjectType);
300  } else if (SS && SS->isNotEmpty()) {
301  LookupCtx = computeDeclContext(*SS, false);
302 
303  if (!LookupCtx) {
304  if (isDependentScopeSpecifier(*SS)) {
305  // C++ [temp.res]p3:
306  // A qualified-id that refers to a type and in which the
307  // nested-name-specifier depends on a template-parameter (14.6.2)
308  // shall be prefixed by the keyword typename to indicate that the
309  // qualified-id denotes a type, forming an
310  // elaborated-type-specifier (7.1.5.3).
311  //
312  // We therefore do not perform any name lookup if the result would
313  // refer to a member of an unknown specialization.
314  if (!isClassName && !IsCtorOrDtorName)
315  return nullptr;
316 
317  // We know from the grammar that this name refers to a type,
318  // so build a dependent node to describe the type.
319  if (WantNontrivialTypeSourceInfo)
320  return ActOnTypenameType(S, SourceLocation(), *SS, II, NameLoc).get();
321 
322  NestedNameSpecifierLoc QualifierLoc = SS->getWithLocInContext(Context);
323  QualType T = CheckTypenameType(ETK_None, SourceLocation(), QualifierLoc,
324  II, NameLoc);
325  return ParsedType::make(T);
326  }
327 
328  return nullptr;
329  }
330 
331  if (!LookupCtx->isDependentContext() &&
332  RequireCompleteDeclContext(*SS, LookupCtx))
333  return nullptr;
334  }
335 
336  // FIXME: LookupNestedNameSpecifierName isn't the right kind of
337  // lookup for class-names.
338  LookupNameKind Kind = isClassName ? LookupNestedNameSpecifierName :
339  LookupOrdinaryName;
340  LookupResult Result(*this, &II, NameLoc, Kind);
341  if (LookupCtx) {
342  // Perform "qualified" name lookup into the declaration context we
343  // computed, which is either the type of the base of a member access
344  // expression or the declaration context associated with a prior
345  // nested-name-specifier.
346  LookupQualifiedName(Result, LookupCtx);
347 
348  if (ObjectTypePtr && Result.empty()) {
349  // C++ [basic.lookup.classref]p3:
350  // If the unqualified-id is ~type-name, the type-name is looked up
351  // in the context of the entire postfix-expression. If the type T of
352  // the object expression is of a class type C, the type-name is also
353  // looked up in the scope of class C. At least one of the lookups shall
354  // find a name that refers to (possibly cv-qualified) T.
355  LookupName(Result, S);
356  }
357  } else {
358  // Perform unqualified name lookup.
359  LookupName(Result, S);
360 
361  // For unqualified lookup in a class template in MSVC mode, look into
362  // dependent base classes where the primary class template is known.
363  if (Result.empty() && getLangOpts().MSVCCompat && (!SS || SS->isEmpty())) {
364  if (ParsedType TypeInBase =
365  recoverFromTypeInKnownDependentBase(*this, II, NameLoc))
366  return TypeInBase;
367  }
368  }
369 
370  NamedDecl *IIDecl = nullptr;
371  switch (Result.getResultKind()) {
374  if (CorrectedII) {
375  TypeNameValidatorCCC CCC(/*AllowInvalid=*/true, isClassName,
376  AllowDeducedTemplate);
377  TypoCorrection Correction = CorrectTypo(Result.getLookupNameInfo(), Kind,
378  S, SS, CCC, CTK_ErrorRecovery);
379  IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
380  TemplateTy Template;
381  bool MemberOfUnknownSpecialization;
383  TemplateName.setIdentifier(NewII, NameLoc);
384  NestedNameSpecifier *NNS = Correction.getCorrectionSpecifier();
385  CXXScopeSpec NewSS, *NewSSPtr = SS;
386  if (SS && NNS) {
387  NewSS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
388  NewSSPtr = &NewSS;
389  }
390  if (Correction && (NNS || NewII != &II) &&
391  // Ignore a correction to a template type as the to-be-corrected
392  // identifier is not a template (typo correction for template names
393  // is handled elsewhere).
394  !(getLangOpts().CPlusPlus && NewSSPtr &&
395  isTemplateName(S, *NewSSPtr, false, TemplateName, nullptr, false,
396  Template, MemberOfUnknownSpecialization))) {
397  ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
398  isClassName, HasTrailingDot, ObjectTypePtr,
399  IsCtorOrDtorName,
400  WantNontrivialTypeSourceInfo,
401  IsClassTemplateDeductionContext);
402  if (Ty) {
403  diagnoseTypo(Correction,
404  PDiag(diag::err_unknown_type_or_class_name_suggest)
405  << Result.getLookupName() << isClassName);
406  if (SS && NNS)
407  SS->MakeTrivial(Context, NNS, SourceRange(NameLoc));
408  *CorrectedII = NewII;
409  return Ty;
410  }
411  }
412  }
413  // If typo correction failed or was not performed, fall through
414  LLVM_FALLTHROUGH;
417  Result.suppressDiagnostics();
418  return nullptr;
419 
421  // Recover from type-hiding ambiguities by hiding the type. We'll
422  // do the lookup again when looking for an object, and we can
423  // diagnose the error then. If we don't do this, then the error
424  // about hiding the type will be immediately followed by an error
425  // that only makes sense if the identifier was treated like a type.
427  Result.suppressDiagnostics();
428  return nullptr;
429  }
430 
431  // Look to see if we have a type anywhere in the list of results.
432  for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
433  Res != ResEnd; ++Res) {
434  if (isa<TypeDecl>(*Res) || isa<ObjCInterfaceDecl>(*Res) ||
435  (AllowDeducedTemplate && getAsTypeTemplateDecl(*Res))) {
436  if (!IIDecl ||
437  (*Res)->getLocation().getRawEncoding() <
438  IIDecl->getLocation().getRawEncoding())
439  IIDecl = *Res;
440  }
441  }
442 
443  if (!IIDecl) {
444  // None of the entities we found is a type, so there is no way
445  // to even assume that the result is a type. In this case, don't
446  // complain about the ambiguity. The parser will either try to
447  // perform this lookup again (e.g., as an object name), which
448  // will produce the ambiguity, or will complain that it expected
449  // a type name.
450  Result.suppressDiagnostics();
451  return nullptr;
452  }
453 
454  // We found a type within the ambiguous lookup; diagnose the
455  // ambiguity and then return that type. This might be the right
456  // answer, or it might not be, but it suppresses any attempt to
457  // perform the name lookup again.
458  break;
459 
460  case LookupResult::Found:
461  IIDecl = Result.getFoundDecl();
462  break;
463  }
464 
465  assert(IIDecl && "Didn't find decl");
466 
467  QualType T;
468  if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
469  // C++ [class.qual]p2: A lookup that would find the injected-class-name
470  // instead names the constructors of the class, except when naming a class.
471  // This is ill-formed when we're not actually forming a ctor or dtor name.
472  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
473  auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
474  if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
475  FoundRD->isInjectedClassName() &&
476  declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
477  Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
478  << &II << /*Type*/1;
479 
480  DiagnoseUseOfDecl(IIDecl, NameLoc);
481 
482  T = Context.getTypeDeclType(TD);
483  MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
484  } else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
485  (void)DiagnoseUseOfDecl(IDecl, NameLoc);
486  if (!HasTrailingDot)
487  T = Context.getObjCInterfaceType(IDecl);
488  } else if (AllowDeducedTemplate) {
489  if (auto *TD = getAsTypeTemplateDecl(IIDecl))
491  QualType(), false);
492  }
493 
494  if (T.isNull()) {
495  // If it's not plausibly a type, suppress diagnostics.
496  Result.suppressDiagnostics();
497  return nullptr;
498  }
499 
500  // NOTE: avoid constructing an ElaboratedType(Loc) if this is a
501  // constructor or destructor name (in such a case, the scope specifier
502  // will be attached to the enclosing Expr or Decl node).
503  if (SS && SS->isNotEmpty() && !IsCtorOrDtorName &&
504  !isa<ObjCInterfaceDecl>(IIDecl)) {
505  if (WantNontrivialTypeSourceInfo) {
506  // Construct a type with type-source information.
507  TypeLocBuilder Builder;
508  Builder.pushTypeSpec(T).setNameLoc(NameLoc);
509 
510  T = getElaboratedType(ETK_None, *SS, T);
511  ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
513  ElabTL.setQualifierLoc(SS->getWithLocInContext(Context));
514  return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
515  } else {
516  T = getElaboratedType(ETK_None, *SS, T);
517  }
518  }
519 
520  return ParsedType::make(T);
521 }
522 
523 // Builds a fake NNS for the given decl context.
524 static NestedNameSpecifier *
526  for (;; DC = DC->getLookupParent()) {
527  DC = DC->getPrimaryContext();
528  auto *ND = dyn_cast<NamespaceDecl>(DC);
529  if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
530  return NestedNameSpecifier::Create(Context, nullptr, ND);
531  else if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
532  return NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
533  RD->getTypeForDecl());
534  else if (isa<TranslationUnitDecl>(DC))
535  return NestedNameSpecifier::GlobalSpecifier(Context);
536  }
537  llvm_unreachable("something isn't in TU scope?");
538 }
539 
540 /// Find the parent class with dependent bases of the innermost enclosing method
541 /// context. Do not look for enclosing CXXRecordDecls directly, or we will end
542 /// up allowing unqualified dependent type names at class-level, which MSVC
543 /// correctly rejects.
544 static const CXXRecordDecl *
546  for (; DC && DC->isDependentContext(); DC = DC->getLookupParent()) {
547  DC = DC->getPrimaryContext();
548  if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
549  if (MD->getParent()->hasAnyDependentBases())
550  return MD->getParent();
551  }
552  return nullptr;
553 }
554 
556  SourceLocation NameLoc,
557  bool IsTemplateTypeArg) {
558  assert(getLangOpts().MSVCCompat && "shouldn't be called in non-MSVC mode");
559 
560  NestedNameSpecifier *NNS = nullptr;
561  if (IsTemplateTypeArg && getCurScope()->isTemplateParamScope()) {
562  // If we weren't able to parse a default template argument, delay lookup
563  // until instantiation time by making a non-dependent DependentTypeName. We
564  // pretend we saw a NestedNameSpecifier referring to the current scope, and
565  // lookup is retried.
566  // FIXME: This hurts our diagnostic quality, since we get errors like "no
567  // type named 'Foo' in 'current_namespace'" when the user didn't write any
568  // name specifiers.
569  NNS = synthesizeCurrentNestedNameSpecifier(Context, CurContext);
570  Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
571  } else if (const CXXRecordDecl *RD =
573  // Build a DependentNameType that will perform lookup into RD at
574  // instantiation time.
575  NNS = NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
576  RD->getTypeForDecl());
577 
578  // Diagnose that this identifier was undeclared, and retry the lookup during
579  // template instantiation.
580  Diag(NameLoc, diag::ext_undeclared_unqual_id_with_dependent_base) << &II
581  << RD;
582  } else {
583  // This is not a situation that we should recover from.
584  return ParsedType();
585  }
586 
587  QualType T = Context.getDependentNameType(ETK_None, NNS, &II);
588 
589  // Build type location information. We synthesized the qualifier, so we have
590  // to build a fake NestedNameSpecifierLoc.
591  NestedNameSpecifierLocBuilder NNSLocBuilder;
592  NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
593  NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);
594 
595  TypeLocBuilder Builder;
596  DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
597  DepTL.setNameLoc(NameLoc);
599  DepTL.setQualifierLoc(QualifierLoc);
600  return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
601 }
602 
603 /// isTagName() - This method is called *for error recovery purposes only*
604 /// to determine if the specified name is a valid tag name ("struct foo"). If
605 /// so, this returns the TST for the tag corresponding to it (TST_enum,
606 /// TST_union, TST_struct, TST_interface, TST_class). This is used to diagnose
607 /// cases in C where the user forgot to specify the tag.
609  // Do a tag name lookup in this scope.
610  LookupResult R(*this, &II, SourceLocation(), LookupTagName);
611  LookupName(R, S, false);
614  if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
615  switch (TD->getTagKind()) {
616  case TTK_Struct: return DeclSpec::TST_struct;
618  case TTK_Union: return DeclSpec::TST_union;
619  case TTK_Class: return DeclSpec::TST_class;
620  case TTK_Enum: return DeclSpec::TST_enum;
621  }
622  }
623 
625 }
626 
627 /// isMicrosoftMissingTypename - In Microsoft mode, within class scope,
628 /// if a CXXScopeSpec's type is equal to the type of one of the base classes
629 /// then downgrade the missing typename error to a warning.
630 /// This is needed for MSVC compatibility; Example:
631 /// @code
632 /// template<class T> class A {
633 /// public:
634 /// typedef int TYPE;
635 /// };
636 /// template<class T> class B : public A<T> {
637 /// public:
638 /// A<T>::TYPE a; // no typename required because A<T> is a base class.
639 /// };
640 /// @endcode
642  if (CurContext->isRecord()) {
644  return true;
645 
646  const Type *Ty = SS->getScopeRep()->getAsType();
647 
648  CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
649  for (const auto &Base : RD->bases())
650  if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
651  return true;
652  return S->isFunctionPrototypeScope();
653  }
654  return CurContext->isFunctionOrMethod() || S->isFunctionPrototypeScope();
655 }
656 
658  SourceLocation IILoc,
659  Scope *S,
660  CXXScopeSpec *SS,
661  ParsedType &SuggestedType,
662  bool IsTemplateName) {
663  // Don't report typename errors for editor placeholders.
664  if (II->isEditorPlaceholder())
665  return;
666  // We don't have anything to suggest (yet).
667  SuggestedType = nullptr;
668 
669  // There may have been a typo in the name of the type. Look up typo
670  // results, in case we have something that we can suggest.
671  TypeNameValidatorCCC CCC(/*AllowInvalid=*/false, /*WantClass=*/false,
672  /*AllowTemplates=*/IsTemplateName,
673  /*AllowNonTemplates=*/!IsTemplateName);
674  if (TypoCorrection Corrected =
675  CorrectTypo(DeclarationNameInfo(II, IILoc), LookupOrdinaryName, S, SS,
676  CCC, CTK_ErrorRecovery)) {
677  // FIXME: Support error recovery for the template-name case.
678  bool CanRecover = !IsTemplateName;
679  if (Corrected.isKeyword()) {
680  // We corrected to a keyword.
681  diagnoseTypo(Corrected,
682  PDiag(IsTemplateName ? diag::err_no_template_suggest
683  : diag::err_unknown_typename_suggest)
684  << II);
685  II = Corrected.getCorrectionAsIdentifierInfo();
686  } else {
687  // We found a similarly-named type or interface; suggest that.
688  if (!SS || !SS->isSet()) {
689  diagnoseTypo(Corrected,
690  PDiag(IsTemplateName ? diag::err_no_template_suggest
691  : diag::err_unknown_typename_suggest)
692  << II, CanRecover);
693  } else if (DeclContext *DC = computeDeclContext(*SS, false)) {
694  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
695  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
696  II->getName().equals(CorrectedStr);
697  diagnoseTypo(Corrected,
698  PDiag(IsTemplateName
699  ? diag::err_no_member_template_suggest
700  : diag::err_unknown_nested_typename_suggest)
701  << II << DC << DroppedSpecifier << SS->getRange(),
702  CanRecover);
703  } else {
704  llvm_unreachable("could not have corrected a typo here");
705  }
706 
707  if (!CanRecover)
708  return;
709 
710  CXXScopeSpec tmpSS;
711  if (Corrected.getCorrectionSpecifier())
712  tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
713  SourceRange(IILoc));
714  // FIXME: Support class template argument deduction here.
715  SuggestedType =
716  getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
717  tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
718  /*IsCtorOrDtorName=*/false,
719  /*WantNontrivialTypeSourceInfo=*/true);
720  }
721  return;
722  }
723 
724  if (getLangOpts().CPlusPlus && !IsTemplateName) {
725  // See if II is a class template that the user forgot to pass arguments to.
726  UnqualifiedId Name;
727  Name.setIdentifier(II, IILoc);
728  CXXScopeSpec EmptySS;
729  TemplateTy TemplateResult;
730  bool MemberOfUnknownSpecialization;
731  if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
732  Name, nullptr, true, TemplateResult,
733  MemberOfUnknownSpecialization) == TNK_Type_template) {
734  diagnoseMissingTemplateArguments(TemplateResult.get(), IILoc);
735  return;
736  }
737  }
738 
739  // FIXME: Should we move the logic that tries to recover from a missing tag
740  // (struct, union, enum) from Parser::ParseImplicitInt here, instead?
741 
742  if (!SS || (!SS->isSet() && !SS->isInvalid()))
743  Diag(IILoc, IsTemplateName ? diag::err_no_template
744  : diag::err_unknown_typename)
745  << II;
746  else if (DeclContext *DC = computeDeclContext(*SS, false))
747  Diag(IILoc, IsTemplateName ? diag::err_no_member_template
748  : diag::err_typename_nested_not_found)
749  << II << DC << SS->getRange();
750  else if (isDependentScopeSpecifier(*SS)) {
751  unsigned DiagID = diag::err_typename_missing;
752  if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
753  DiagID = diag::ext_typename_missing;
754 
755  Diag(SS->getRange().getBegin(), DiagID)
756  << SS->getScopeRep() << II->getName()
757  << SourceRange(SS->getRange().getBegin(), IILoc)
758  << FixItHint::CreateInsertion(SS->getRange().getBegin(), "typename ");
759  SuggestedType = ActOnTypenameType(S, SourceLocation(),
760  *SS, *II, IILoc).get();
761  } else {
762  assert(SS && SS->isInvalid() &&
763  "Invalid scope specifier has already been diagnosed");
764  }
765 }
766 
767 /// Determine whether the given result set contains either a type name
768 /// or
769 static bool isResultTypeOrTemplate(LookupResult &R, const Token &NextToken) {
770  bool CheckTemplate = R.getSema().getLangOpts().CPlusPlus &&
771  NextToken.is(tok::less);
772 
773  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
774  if (isa<TypeDecl>(*I) || isa<ObjCInterfaceDecl>(*I))
775  return true;
776 
777  if (CheckTemplate && isa<TemplateDecl>(*I))
778  return true;
779  }
780 
781  return false;
782 }
783 
784 static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
785  Scope *S, CXXScopeSpec &SS,
786  IdentifierInfo *&Name,
787  SourceLocation NameLoc) {
788  LookupResult R(SemaRef, Name, NameLoc, Sema::LookupTagName);
789  SemaRef.LookupParsedName(R, S, &SS);
790  if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
791  StringRef FixItTagName;
792  switch (Tag->getTagKind()) {
793  case TTK_Class:
794  FixItTagName = "class ";
795  break;
796 
797  case TTK_Enum:
798  FixItTagName = "enum ";
799  break;
800 
801  case TTK_Struct:
802  FixItTagName = "struct ";
803  break;
804 
805  case TTK_Interface:
806  FixItTagName = "__interface ";
807  break;
808 
809  case TTK_Union:
810  FixItTagName = "union ";
811  break;
812  }
813 
814  StringRef TagName = FixItTagName.drop_back();
815  SemaRef.Diag(NameLoc, diag::err_use_of_tag_name_without_tag)
816  << Name << TagName << SemaRef.getLangOpts().CPlusPlus
817  << FixItHint::CreateInsertion(NameLoc, FixItTagName);
818 
819  for (LookupResult::iterator I = Result.begin(), IEnd = Result.end();
820  I != IEnd; ++I)
821  SemaRef.Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
822  << Name << TagName;
823 
824  // Replace lookup results with just the tag decl.
825  Result.clear(Sema::LookupTagName);
826  SemaRef.LookupParsedName(Result, S, &SS);
827  return true;
828  }
829 
830  return false;
831 }
832 
833 /// Build a ParsedType for a simple-type-specifier with a nested-name-specifier.
835  QualType T, SourceLocation NameLoc) {
836  ASTContext &Context = S.Context;
837 
838  TypeLocBuilder Builder;
839  Builder.pushTypeSpec(T).setNameLoc(NameLoc);
840 
841  T = S.getElaboratedType(ETK_None, SS, T);
842  ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
844  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
845  return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
846 }
847 
849  IdentifierInfo *&Name,
850  SourceLocation NameLoc,
851  const Token &NextToken,
853  DeclarationNameInfo NameInfo(Name, NameLoc);
854  ObjCMethodDecl *CurMethod = getCurMethodDecl();
855 
856  assert(NextToken.isNot(tok::coloncolon) &&
857  "parse nested name specifiers before calling ClassifyName");
858  if (getLangOpts().CPlusPlus && SS.isSet() &&
859  isCurrentClassName(*Name, S, &SS)) {
860  // Per [class.qual]p2, this names the constructors of SS, not the
861  // injected-class-name. We don't have a classification for that.
862  // There's not much point caching this result, since the parser
863  // will reject it later.
865  }
866 
867  LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
868  LookupParsedName(Result, S, &SS, !CurMethod);
869 
870  // For unqualified lookup in a class template in MSVC mode, look into
871  // dependent base classes where the primary class template is known.
872  if (Result.empty() && SS.isEmpty() && getLangOpts().MSVCCompat) {
873  if (ParsedType TypeInBase =
874  recoverFromTypeInKnownDependentBase(*this, *Name, NameLoc))
875  return TypeInBase;
876  }
877 
878  // Perform lookup for Objective-C instance variables (including automatically
879  // synthesized instance variables), if we're in an Objective-C method.
880  // FIXME: This lookup really, really needs to be folded in to the normal
881  // unqualified lookup mechanism.
882  if (!SS.isSet() && CurMethod && !isResultTypeOrTemplate(Result, NextToken)) {
883  DeclResult Ivar = LookupIvarInObjCMethod(Result, S, Name);
884  if (Ivar.isInvalid())
885  return NameClassification::Error();
886  if (Ivar.isUsable())
887  return NameClassification::NonType(cast<NamedDecl>(Ivar.get()));
888 
889  // We defer builtin creation until after ivar lookup inside ObjC methods.
890  if (Result.empty())
891  LookupBuiltin(Result);
892  }
893 
894  bool SecondTry = false;
895  bool IsFilteredTemplateName = false;
896 
897 Corrected:
898  switch (Result.getResultKind()) {
900  // If an unqualified-id is followed by a '(', then we have a function
901  // call.
902  if (!SS.isSet() && NextToken.is(tok::l_paren)) {
903  // In C++, this is an ADL-only call.
904  // FIXME: Reference?
905  if (getLangOpts().CPlusPlus)
906  return NameClassification::UndeclaredNonType();
907 
908  // C90 6.3.2.2:
909  // If the expression that precedes the parenthesized argument list in a
910  // function call consists solely of an identifier, and if no
911  // declaration is visible for this identifier, the identifier is
912  // implicitly declared exactly as if, in the innermost block containing
913  // the function call, the declaration
914  //
915  // extern int identifier ();
916  //
917  // appeared.
918  //
919  // We also allow this in C99 as an extension.
920  if (NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *Name, S))
921  return NameClassification::NonType(D);
922  }
923 
924  if (getLangOpts().CPlusPlus2a && !SS.isSet() && NextToken.is(tok::less)) {
925  // In C++20 onwards, this could be an ADL-only call to a function
926  // template, and we're required to assume that this is a template name.
927  //
928  // FIXME: Find a way to still do typo correction in this case.
929  TemplateName Template =
930  Context.getAssumedTemplateName(NameInfo.getName());
931  return NameClassification::UndeclaredTemplate(Template);
932  }
933 
934  // In C, we first see whether there is a tag type by the same name, in
935  // which case it's likely that the user just forgot to write "enum",
936  // "struct", or "union".
937  if (!getLangOpts().CPlusPlus && !SecondTry &&
938  isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
939  break;
940  }
941 
942  // Perform typo correction to determine if there is another name that is
943  // close to this name.
944  if (!SecondTry && CCC) {
945  SecondTry = true;
946  if (TypoCorrection Corrected =
947  CorrectTypo(Result.getLookupNameInfo(), Result.getLookupKind(), S,
948  &SS, *CCC, CTK_ErrorRecovery)) {
949  unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
950  unsigned QualifiedDiag = diag::err_no_member_suggest;
951 
952  NamedDecl *FirstDecl = Corrected.getFoundDecl();
953  NamedDecl *UnderlyingFirstDecl = Corrected.getCorrectionDecl();
954  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
955  UnderlyingFirstDecl && isa<TemplateDecl>(UnderlyingFirstDecl)) {
956  UnqualifiedDiag = diag::err_no_template_suggest;
957  QualifiedDiag = diag::err_no_member_template_suggest;
958  } else if (UnderlyingFirstDecl &&
959  (isa<TypeDecl>(UnderlyingFirstDecl) ||
960  isa<ObjCInterfaceDecl>(UnderlyingFirstDecl) ||
961  isa<ObjCCompatibleAliasDecl>(UnderlyingFirstDecl))) {
962  UnqualifiedDiag = diag::err_unknown_typename_suggest;
963  QualifiedDiag = diag::err_unknown_nested_typename_suggest;
964  }
965 
966  if (SS.isEmpty()) {
967  diagnoseTypo(Corrected, PDiag(UnqualifiedDiag) << Name);
968  } else {// FIXME: is this even reachable? Test it.
969  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
970  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
971  Name->getName().equals(CorrectedStr);
972  diagnoseTypo(Corrected, PDiag(QualifiedDiag)
973  << Name << computeDeclContext(SS, false)
974  << DroppedSpecifier << SS.getRange());
975  }
976 
977  // Update the name, so that the caller has the new name.
978  Name = Corrected.getCorrectionAsIdentifierInfo();
979 
980  // Typo correction corrected to a keyword.
981  if (Corrected.isKeyword())
982  return Name;
983 
984  // Also update the LookupResult...
985  // FIXME: This should probably go away at some point
986  Result.clear();
987  Result.setLookupName(Corrected.getCorrection());
988  if (FirstDecl)
989  Result.addDecl(FirstDecl);
990 
991  // If we found an Objective-C instance variable, let
992  // LookupInObjCMethod build the appropriate expression to
993  // reference the ivar.
994  // FIXME: This is a gross hack.
995  if (ObjCIvarDecl *Ivar = Result.getAsSingle<ObjCIvarDecl>()) {
996  DeclResult R =
997  LookupIvarInObjCMethod(Result, S, Ivar->getIdentifier());
998  if (R.isInvalid())
999  return NameClassification::Error();
1000  if (R.isUsable())
1001  return NameClassification::NonType(Ivar);
1002  }
1003 
1004  goto Corrected;
1005  }
1006  }
1007 
1008  // We failed to correct; just fall through and let the parser deal with it.
1009  Result.suppressDiagnostics();
1010  return NameClassification::Unknown();
1011 
1013  // We performed name lookup into the current instantiation, and there were
1014  // dependent bases, so we treat this result the same way as any other
1015  // dependent nested-name-specifier.
1016 
1017  // C++ [temp.res]p2:
1018  // A name used in a template declaration or definition and that is
1019  // dependent on a template-parameter is assumed not to name a type
1020  // unless the applicable name lookup finds a type name or the name is
1021  // qualified by the keyword typename.
1022  //
1023  // FIXME: If the next token is '<', we might want to ask the parser to
1024  // perform some heroics to see if we actually have a
1025  // template-argument-list, which would indicate a missing 'template'
1026  // keyword here.
1027  return NameClassification::DependentNonType();
1028  }
1029 
1030  case LookupResult::Found:
1033  break;
1034 
1036  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
1037  hasAnyAcceptableTemplateNames(Result, /*AllowFunctionTemplates=*/true,
1038  /*AllowDependent=*/false)) {
1039  // C++ [temp.local]p3:
1040  // A lookup that finds an injected-class-name (10.2) can result in an
1041  // ambiguity in certain cases (for example, if it is found in more than
1042  // one base class). If all of the injected-class-names that are found
1043  // refer to specializations of the same class template, and if the name
1044  // is followed by a template-argument-list, the reference refers to the
1045  // class template itself and not a specialization thereof, and is not
1046  // ambiguous.
1047  //
1048  // This filtering can make an ambiguous result into an unambiguous one,
1049  // so try again after filtering out template names.
1050  FilterAcceptableTemplateNames(Result);
1051  if (!Result.isAmbiguous()) {
1052  IsFilteredTemplateName = true;
1053  break;
1054  }
1055  }
1056 
1057  // Diagnose the ambiguity and return an error.
1058  return NameClassification::Error();
1059  }
1060 
1061  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
1062  (IsFilteredTemplateName ||
1063  hasAnyAcceptableTemplateNames(
1064  Result, /*AllowFunctionTemplates=*/true,
1065  /*AllowDependent=*/false,
1066  /*AllowNonTemplateFunctions*/ !SS.isSet() &&
1067  getLangOpts().CPlusPlus2a))) {
1068  // C++ [temp.names]p3:
1069  // After name lookup (3.4) finds that a name is a template-name or that
1070  // an operator-function-id or a literal- operator-id refers to a set of
1071  // overloaded functions any member of which is a function template if
1072  // this is followed by a <, the < is always taken as the delimiter of a
1073  // template-argument-list and never as the less-than operator.
1074  // C++2a [temp.names]p2:
1075  // A name is also considered to refer to a template if it is an
1076  // unqualified-id followed by a < and name lookup finds either one
1077  // or more functions or finds nothing.
1078  if (!IsFilteredTemplateName)
1079  FilterAcceptableTemplateNames(Result);
1080 
1081  bool IsFunctionTemplate;
1082  bool IsVarTemplate;
1083  TemplateName Template;
1084  if (Result.end() - Result.begin() > 1) {
1085  IsFunctionTemplate = true;
1086  Template = Context.getOverloadedTemplateName(Result.begin(),
1087  Result.end());
1088  } else if (!Result.empty()) {
1089  auto *TD = cast<TemplateDecl>(getAsTemplateNameDecl(
1090  *Result.begin(), /*AllowFunctionTemplates=*/true,
1091  /*AllowDependent=*/false));
1092  IsFunctionTemplate = isa<FunctionTemplateDecl>(TD);
1093  IsVarTemplate = isa<VarTemplateDecl>(TD);
1094 
1095  if (SS.isSet() && !SS.isInvalid())
1096  Template =
1098  /*TemplateKeyword=*/false, TD);
1099  else
1100  Template = TemplateName(TD);
1101  } else {
1102  // All results were non-template functions. This is a function template
1103  // name.
1104  IsFunctionTemplate = true;
1105  Template = Context.getAssumedTemplateName(NameInfo.getName());
1106  }
1107 
1108  if (IsFunctionTemplate) {
1109  // Function templates always go through overload resolution, at which
1110  // point we'll perform the various checks (e.g., accessibility) we need
1111  // to based on which function we selected.
1112  Result.suppressDiagnostics();
1113 
1114  return NameClassification::FunctionTemplate(Template);
1115  }
1116 
1117  return IsVarTemplate ? NameClassification::VarTemplate(Template)
1118  : NameClassification::TypeTemplate(Template);
1119  }
1120 
1121  NamedDecl *FirstDecl = (*Result.begin())->getUnderlyingDecl();
1122  if (TypeDecl *Type = dyn_cast<TypeDecl>(FirstDecl)) {
1123  DiagnoseUseOfDecl(Type, NameLoc);
1124  MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
1125  QualType T = Context.getTypeDeclType(Type);
1126  if (SS.isNotEmpty())
1127  return buildNestedType(*this, SS, T, NameLoc);
1128  return ParsedType::make(T);
1129  }
1130 
1131  ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(FirstDecl);
1132  if (!Class) {
1133  // FIXME: It's unfortunate that we don't have a Type node for handling this.
1134  if (ObjCCompatibleAliasDecl *Alias =
1135  dyn_cast<ObjCCompatibleAliasDecl>(FirstDecl))
1136  Class = Alias->getClassInterface();
1137  }
1138 
1139  if (Class) {
1140  DiagnoseUseOfDecl(Class, NameLoc);
1141 
1142  if (NextToken.is(tok::period)) {
1143  // Interface. <something> is parsed as a property reference expression.
1144  // Just return "unknown" as a fall-through for now.
1145  Result.suppressDiagnostics();
1146  return NameClassification::Unknown();
1147  }
1148 
1149  QualType T = Context.getObjCInterfaceType(Class);
1150  return ParsedType::make(T);
1151  }
1152 
1153  // We can have a type template here if we're classifying a template argument.
1154  if (isa<TemplateDecl>(FirstDecl) && !isa<FunctionTemplateDecl>(FirstDecl) &&
1155  !isa<VarTemplateDecl>(FirstDecl))
1156  return NameClassification::TypeTemplate(
1157  TemplateName(cast<TemplateDecl>(FirstDecl)));
1158 
1159  // Check for a tag type hidden by a non-type decl in a few cases where it
1160  // seems likely a type is wanted instead of the non-type that was found.
1161  bool NextIsOp = NextToken.isOneOf(tok::amp, tok::star);
1162  if ((NextToken.is(tok::identifier) ||
1163  (NextIsOp &&
1164  FirstDecl->getUnderlyingDecl()->isFunctionOrFunctionTemplate())) &&
1165  isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
1166  TypeDecl *Type = Result.getAsSingle<TypeDecl>();
1167  DiagnoseUseOfDecl(Type, NameLoc);
1168  QualType T = Context.getTypeDeclType(Type);
1169  if (SS.isNotEmpty())
1170  return buildNestedType(*this, SS, T, NameLoc);
1171  return ParsedType::make(T);
1172  }
1173 
1174  // FIXME: This is context-dependent. We need to defer building the member
1175  // expression until the classification is consumed.
1176  if (FirstDecl->isCXXClassMember())
1177  return NameClassification::ContextIndependentExpr(
1178  BuildPossibleImplicitMemberExpr(SS, SourceLocation(), Result, nullptr,
1179  S));
1180 
1181  // If we already know which single declaration is referenced, just annotate
1182  // that declaration directly.
1183  bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
1184  if (Result.isSingleResult() && !ADL)
1185  return NameClassification::NonType(Result.getRepresentativeDecl());
1186 
1187  // Build an UnresolvedLookupExpr. Note that this doesn't depend on the
1188  // context in which we performed classification, so it's safe to do now.
1189  return NameClassification::ContextIndependentExpr(
1190  BuildDeclarationNameExpr(SS, Result, ADL));
1191 }
1192 
1193 ExprResult
1195  SourceLocation NameLoc) {
1196  assert(getLangOpts().CPlusPlus && "ADL-only call in C?");
1197  CXXScopeSpec SS;
1198  LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
1199  return BuildDeclarationNameExpr(SS, Result, /*ADL=*/true);
1200 }
1201 
1202 ExprResult
1204  IdentifierInfo *Name,
1205  SourceLocation NameLoc,
1206  bool IsAddressOfOperand) {
1207  DeclarationNameInfo NameInfo(Name, NameLoc);
1208  return ActOnDependentIdExpression(SS, /*TemplateKWLoc=*/SourceLocation(),
1209  NameInfo, IsAddressOfOperand,
1210  /*TemplateArgs=*/nullptr);
1211 }
1212 
1214  NamedDecl *Found,
1215  SourceLocation NameLoc,
1216  const Token &NextToken) {
1217  if (getCurMethodDecl() && SS.isEmpty())
1218  if (auto *Ivar = dyn_cast<ObjCIvarDecl>(Found->getUnderlyingDecl()))
1219  return BuildIvarRefExpr(S, NameLoc, Ivar);
1220 
1221  // Reconstruct the lookup result.
1222  LookupResult Result(*this, Found->getDeclName(), NameLoc, LookupOrdinaryName);
1223  Result.addDecl(Found);
1224  Result.resolveKind();
1225 
1226  bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
1227  return BuildDeclarationNameExpr(SS, Result, ADL);
1228 }
1229 
1232  auto *TD = Name.getAsTemplateDecl();
1233  if (!TD)
1234  return TemplateNameKindForDiagnostics::DependentTemplate;
1235  if (isa<ClassTemplateDecl>(TD))
1236  return TemplateNameKindForDiagnostics::ClassTemplate;
1237  if (isa<FunctionTemplateDecl>(TD))
1238  return TemplateNameKindForDiagnostics::FunctionTemplate;
1239  if (isa<VarTemplateDecl>(TD))
1240  return TemplateNameKindForDiagnostics::VarTemplate;
1241  if (isa<TypeAliasTemplateDecl>(TD))
1242  return TemplateNameKindForDiagnostics::AliasTemplate;
1243  if (isa<TemplateTemplateParmDecl>(TD))
1244  return TemplateNameKindForDiagnostics::TemplateTemplateParam;
1245  if (isa<ConceptDecl>(TD))
1246  return TemplateNameKindForDiagnostics::Concept;
1247  return TemplateNameKindForDiagnostics::DependentTemplate;
1248 }
1249 
1250 // Determines the context to return to after temporarily entering a
1251 // context. This depends in an unnecessarily complicated way on the
1252 // exact ordering of callbacks from the parser.
1254 
1255  // Functions defined inline within classes aren't parsed until we've
1256  // finished parsing the top-level class, so the top-level class is
1257  // the context we'll need to return to.
1258  // A Lambda call operator whose parent is a class must not be treated
1259  // as an inline member function. A Lambda can be used legally
1260  // either as an in-class member initializer or a default argument. These
1261  // are parsed once the class has been marked complete and so the containing
1262  // context would be the nested class (when the lambda is defined in one);
1263  // If the class is not complete, then the lambda is being used in an
1264  // ill-formed fashion (such as to specify the width of a bit-field, or
1265  // in an array-bound) - in which case we still want to return the
1266  // lexically containing DC (which could be a nested class).
1267  if (isa<FunctionDecl>(DC) && !isLambdaCallOperator(DC)) {
1268  DC = DC->getLexicalParent();
1269 
1270  // A function not defined within a class will always return to its
1271  // lexical context.
1272  if (!isa<CXXRecordDecl>(DC))
1273  return DC;
1274 
1275  // A C++ inline method/friend is parsed *after* the topmost class
1276  // it was declared in is fully parsed ("complete"); the topmost
1277  // class is the context we need to return to.
1278  while (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC->getLexicalParent()))
1279  DC = RD;
1280 
1281  // Return the declaration context of the topmost class the inline method is
1282  // declared in.
1283  return DC;
1284  }
1285 
1286  return DC->getLexicalParent();
1287 }
1288 
1290  assert(getContainingDC(DC) == CurContext &&
1291  "The next DeclContext should be lexically contained in the current one.");
1292  CurContext = DC;
1293  S->setEntity(DC);
1294 }
1295 
1297  assert(CurContext && "DeclContext imbalance!");
1298 
1299  CurContext = getContainingDC(CurContext);
1300  assert(CurContext && "Popped translation unit!");
1301 }
1302 
1304  Decl *D) {
1305  // Unlike PushDeclContext, the context to which we return is not necessarily
1306  // the containing DC of TD, because the new context will be some pre-existing
1307  // TagDecl definition instead of a fresh one.
1308  auto Result = static_cast<SkippedDefinitionContext>(CurContext);
1309  CurContext = cast<TagDecl>(D)->getDefinition();
1310  assert(CurContext && "skipping definition of undefined tag");
1311  // Start lookups from the parent of the current context; we don't want to look
1312  // into the pre-existing complete definition.
1313  S->setEntity(CurContext->getLookupParent());
1314  return Result;
1315 }
1316 
1318  CurContext = static_cast<decltype(CurContext)>(Context);
1319 }
1320 
1321 /// EnterDeclaratorContext - Used when we must lookup names in the context
1322 /// of a declarator's nested name specifier.
1323 ///
1325  // C++0x [basic.lookup.unqual]p13:
1326  // A name used in the definition of a static data member of class
1327  // X (after the qualified-id of the static member) is looked up as
1328  // if the name was used in a member function of X.
1329  // C++0x [basic.lookup.unqual]p14:
1330  // If a variable member of a namespace is defined outside of the
1331  // scope of its namespace then any name used in the definition of
1332  // the variable member (after the declarator-id) is looked up as
1333  // if the definition of the variable member occurred in its
1334  // namespace.
1335  // Both of these imply that we should push a scope whose context
1336  // is the semantic context of the declaration. We can't use
1337  // PushDeclContext here because that context is not necessarily
1338  // lexically contained in the current context. Fortunately,
1339  // the containing scope should have the appropriate information.
1340 
1341  assert(!S->getEntity() && "scope already has entity");
1342 
1343 #ifndef NDEBUG
1344  Scope *Ancestor = S->getParent();
1345  while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
1346  assert(Ancestor->getEntity() == CurContext && "ancestor context mismatch");
1347 #endif
1348 
1349  CurContext = DC;
1350  S->setEntity(DC);
1351 }
1352 
1354  assert(S->getEntity() == CurContext && "Context imbalance!");
1355 
1356  // Switch back to the lexical context. The safety of this is
1357  // enforced by an assert in EnterDeclaratorContext.
1358  Scope *Ancestor = S->getParent();
1359  while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
1360  CurContext = Ancestor->getEntity();
1361 
1362  // We don't need to do anything with the scope, which is going to
1363  // disappear.
1364 }
1365 
1367  // We assume that the caller has already called
1368  // ActOnReenterTemplateScope so getTemplatedDecl() works.
1369  FunctionDecl *FD = D->getAsFunction();
1370  if (!FD)
1371  return;
1372 
1373  // Same implementation as PushDeclContext, but enters the context
1374  // from the lexical parent, rather than the top-level class.
1375  assert(CurContext == FD->getLexicalParent() &&
1376  "The next DeclContext should be lexically contained in the current one.");
1377  CurContext = FD;
1378  S->setEntity(CurContext);
1379 
1380  for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
1381  ParmVarDecl *Param = FD->getParamDecl(P);
1382  // If the parameter has an identifier, then add it to the scope
1383  if (Param->getIdentifier()) {
1384  S->AddDecl(Param);
1385  IdResolver.AddDecl(Param);
1386  }
1387  }
1388 }
1389 
1391  // Same implementation as PopDeclContext, but returns to the lexical parent,
1392  // rather than the top-level class.
1393  assert(CurContext && "DeclContext imbalance!");
1394  CurContext = CurContext->getLexicalParent();
1395  assert(CurContext && "Popped translation unit!");
1396 }
1397 
1398 /// Determine whether we allow overloading of the function
1399 /// PrevDecl with another declaration.
1400 ///
1401 /// This routine determines whether overloading is possible, not
1402 /// whether some new function is actually an overload. It will return
1403 /// true in C++ (where we can always provide overloads) or, as an
1404 /// extension, in C when the previous function is already an
1405 /// overloaded function declaration or has the "overloadable"
1406 /// attribute.
1408  ASTContext &Context,
1409  const FunctionDecl *New) {
1410  if (Context.getLangOpts().CPlusPlus)
1411  return true;
1412 
1413  if (Previous.getResultKind() == LookupResult::FoundOverloaded)
1414  return true;
1415 
1416  return Previous.getResultKind() == LookupResult::Found &&
1417  (Previous.getFoundDecl()->hasAttr<OverloadableAttr>() ||
1418  New->hasAttr<OverloadableAttr>());
1419 }
1420 
1421 /// Add this decl to the scope shadowed decl chains.
1422 void Sema::PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext) {
1423  // Move up the scope chain until we find the nearest enclosing
1424  // non-transparent context. The declaration will be introduced into this
1425  // scope.
1426  while (S->getEntity() && S->getEntity()->isTransparentContext())
1427  S = S->getParent();
1428 
1429  // Add scoped declarations into their context, so that they can be
1430  // found later. Declarations without a context won't be inserted
1431  // into any context.
1432  if (AddToContext)
1433  CurContext->addDecl(D);
1434 
1435  // Out-of-line definitions shouldn't be pushed into scope in C++, unless they
1436  // are function-local declarations.
1437  if (getLangOpts().CPlusPlus && D->isOutOfLine() &&
1441  return;
1442 
1443  // Template instantiations should also not be pushed into scope.
1444  if (isa<FunctionDecl>(D) &&
1445  cast<FunctionDecl>(D)->isFunctionTemplateSpecialization())
1446  return;
1447 
1448  // If this replaces anything in the current scope,
1449  IdentifierResolver::iterator I = IdResolver.begin(D->getDeclName()),
1450  IEnd = IdResolver.end();
1451  for (; I != IEnd; ++I) {
1452  if (S->isDeclScope(*I) && D->declarationReplaces(*I)) {
1453  S->RemoveDecl(*I);
1454  IdResolver.RemoveDecl(*I);
1455 
1456  // Should only need to replace one decl.
1457  break;
1458  }
1459  }
1460 
1461  S->AddDecl(D);
1462 
1463  if (isa<LabelDecl>(D) && !cast<LabelDecl>(D)->isGnuLocal()) {
1464  // Implicitly-generated labels may end up getting generated in an order that
1465  // isn't strictly lexical, which breaks name lookup. Be careful to insert
1466  // the label at the appropriate place in the identifier chain.
1467  for (I = IdResolver.begin(D->getDeclName()); I != IEnd; ++I) {
1468  DeclContext *IDC = (*I)->getLexicalDeclContext()->getRedeclContext();
1469  if (IDC == CurContext) {
1470  if (!S->isDeclScope(*I))
1471  continue;
1472  } else if (IDC->Encloses(CurContext))
1473  break;
1474  }
1475 
1476  IdResolver.InsertDeclAfter(I, D);
1477  } else {
1478  IdResolver.AddDecl(D);
1479  }
1480 }
1481 
1483  bool AllowInlineNamespace) {
1484  return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
1485 }
1486 
1488  DeclContext *TargetDC = DC->getPrimaryContext();
1489  do {
1490  if (DeclContext *ScopeDC = S->getEntity())
1491  if (ScopeDC->getPrimaryContext() == TargetDC)
1492  return S;
1493  } while ((S = S->getParent()));
1494 
1495  return nullptr;
1496 }
1497 
1499  DeclContext*,
1500  ASTContext&);
1501 
1502 /// Filters out lookup results that don't fall within the given scope
1503 /// as determined by isDeclInScope.
1505  bool ConsiderLinkage,
1506  bool AllowInlineNamespace) {
1508  while (F.hasNext()) {
1509  NamedDecl *D = F.next();
1510 
1511  if (isDeclInScope(D, Ctx, S, AllowInlineNamespace))
1512  continue;
1513 
1514  if (ConsiderLinkage && isOutOfScopePreviousDeclaration(D, Ctx, Context))
1515  continue;
1516 
1517  F.erase();
1518  }
1519 
1520  F.done();
1521 }
1522 
1523 /// We've determined that \p New is a redeclaration of \p Old. Check that they
1524 /// have compatible owning modules.
1526  // FIXME: The Modules TS is not clear about how friend declarations are
1527  // to be treated. It's not meaningful to have different owning modules for
1528  // linkage in redeclarations of the same entity, so for now allow the
1529  // redeclaration and change the owning modules to match.
1530  if (New->getFriendObjectKind() &&
1533  makeMergedDefinitionVisible(New);
1534  return false;
1535  }
1536 
1537  Module *NewM = New->getOwningModule();
1538  Module *OldM = Old->getOwningModule();
1539 
1540  if (NewM && NewM->Kind == Module::PrivateModuleFragment)
1541  NewM = NewM->Parent;
1542  if (OldM && OldM->Kind == Module::PrivateModuleFragment)
1543  OldM = OldM->Parent;
1544 
1545  if (NewM == OldM)
1546  return false;
1547 
1548  bool NewIsModuleInterface = NewM && NewM->isModulePurview();
1549  bool OldIsModuleInterface = OldM && OldM->isModulePurview();
1550  if (NewIsModuleInterface || OldIsModuleInterface) {
1551  // C++ Modules TS [basic.def.odr] 6.2/6.7 [sic]:
1552  // if a declaration of D [...] appears in the purview of a module, all
1553  // other such declarations shall appear in the purview of the same module
1554  Diag(New->getLocation(), diag::err_mismatched_owning_module)
1555  << New
1556  << NewIsModuleInterface
1557  << (NewIsModuleInterface ? NewM->getFullModuleName() : "")
1558  << OldIsModuleInterface
1559  << (OldIsModuleInterface ? OldM->getFullModuleName() : "");
1560  Diag(Old->getLocation(), diag::note_previous_declaration);
1561  New->setInvalidDecl();
1562  return true;
1563  }
1564 
1565  return false;
1566 }
1567 
1568 static bool isUsingDecl(NamedDecl *D) {
1569  return isa<UsingShadowDecl>(D) ||
1570  isa<UnresolvedUsingTypenameDecl>(D) ||
1571  isa<UnresolvedUsingValueDecl>(D);
1572 }
1573 
1574 /// Removes using shadow declarations from the lookup results.
1577  while (F.hasNext())
1578  if (isUsingDecl(F.next()))
1579  F.erase();
1580 
1581  F.done();
1582 }
1583 
1584 /// Check for this common pattern:
1585 /// @code
1586 /// class S {
1587 /// S(const S&); // DO NOT IMPLEMENT
1588 /// void operator=(const S&); // DO NOT IMPLEMENT
1589 /// };
1590 /// @endcode
1592  // FIXME: Should check for private access too but access is set after we get
1593  // the decl here.
1595  return false;
1596 
1597  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
1598  return CD->isCopyConstructor();
1599  return D->isCopyAssignmentOperator();
1600 }
1601 
1602 // We need this to handle
1603 //
1604 // typedef struct {
1605 // void *foo() { return 0; }
1606 // } A;
1607 //
1608 // When we see foo we don't know if after the typedef we will get 'A' or '*A'
1609 // for example. If 'A', foo will have external linkage. If we have '*A',
1610 // foo will have no linkage. Since we can't know until we get to the end
1611 // of the typedef, this function finds out if D might have non-external linkage.
1612 // Callers should verify at the end of the TU if it D has external linkage or
1613 // not.
1614 bool Sema::mightHaveNonExternalLinkage(const DeclaratorDecl *D) {
1615  const DeclContext *DC = D->getDeclContext();
1616  while (!DC->isTranslationUnit()) {
1617  if (const RecordDecl *RD = dyn_cast<RecordDecl>(DC)){
1618  if (!RD->hasNameForLinkage())
1619  return true;
1620  }
1621  DC = DC->getParent();
1622  }
1623 
1624  return !D->isExternallyVisible();
1625 }
1626 
1627 // FIXME: This needs to be refactored; some other isInMainFile users want
1628 // these semantics.
1629 static bool isMainFileLoc(const Sema &S, SourceLocation Loc) {
1630  if (S.TUKind != TU_Complete)
1631  return false;
1632  return S.SourceMgr.isInMainFile(Loc);
1633 }
1634 
1636  assert(D);
1637 
1638  if (D->isInvalidDecl() || D->isUsed() || D->hasAttr<UnusedAttr>())
1639  return false;
1640 
1641  // Ignore all entities declared within templates, and out-of-line definitions
1642  // of members of class templates.
1643  if (D->getDeclContext()->isDependentContext() ||
1645  return false;
1646 
1647  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1648  if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
1649  return false;
1650  // A non-out-of-line declaration of a member specialization was implicitly
1651  // instantiated; it's the out-of-line declaration that we're interested in.
1652  if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
1653  FD->getMemberSpecializationInfo() && !FD->isOutOfLine())
1654  return false;
1655 
1656  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
1657  if (MD->isVirtual() || IsDisallowedCopyOrAssign(MD))
1658  return false;
1659  } else {
1660  // 'static inline' functions are defined in headers; don't warn.
1661  if (FD->isInlined() && !isMainFileLoc(*this, FD->getLocation()))
1662  return false;
1663  }
1664 
1665  if (FD->doesThisDeclarationHaveABody() &&
1666  Context.DeclMustBeEmitted(FD))
1667  return false;
1668  } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1669  // Constants and utility variables are defined in headers with internal
1670  // linkage; don't warn. (Unlike functions, there isn't a convenient marker
1671  // like "inline".)
1672  if (!isMainFileLoc(*this, VD->getLocation()))
1673  return false;
1674 
1675  if (Context.DeclMustBeEmitted(VD))
1676  return false;
1677 
1678  if (VD->isStaticDataMember() &&
1679  VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
1680  return false;
1681  if (VD->isStaticDataMember() &&
1682  VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
1683  VD->getMemberSpecializationInfo() && !VD->isOutOfLine())
1684  return false;
1685 
1686  if (VD->isInline() && !isMainFileLoc(*this, VD->getLocation()))
1687  return false;
1688  } else {
1689  return false;
1690  }
1691 
1692  // Only warn for unused decls internal to the translation unit.
1693  // FIXME: This seems like a bogus check; it suppresses -Wunused-function
1694  // for inline functions defined in the main source file, for instance.
1695  return mightHaveNonExternalLinkage(D);
1696 }
1697 
1699  if (!D)
1700  return;
1701 
1702  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1703  const FunctionDecl *First = FD->getFirstDecl();
1704  if (FD != First && ShouldWarnIfUnusedFileScopedDecl(First))
1705  return; // First should already be in the vector.
1706  }
1707 
1708  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1709  const VarDecl *First = VD->getFirstDecl();
1710  if (VD != First && ShouldWarnIfUnusedFileScopedDecl(First))
1711  return; // First should already be in the vector.
1712  }
1713 
1714  if (ShouldWarnIfUnusedFileScopedDecl(D))
1715  UnusedFileScopedDecls.push_back(D);
1716 }
1717 
1718 static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
1719  if (D->isInvalidDecl())
1720  return false;
1721 
1722  bool Referenced = false;
1723  if (auto *DD = dyn_cast<DecompositionDecl>(D)) {
1724  // For a decomposition declaration, warn if none of the bindings are
1725  // referenced, instead of if the variable itself is referenced (which
1726  // it is, by the bindings' expressions).
1727  for (auto *BD : DD->bindings()) {
1728  if (BD->isReferenced()) {
1729  Referenced = true;
1730  break;
1731  }
1732  }
1733  } else if (!D->getDeclName()) {
1734  return false;
1735  } else if (D->isReferenced() || D->isUsed()) {
1736  Referenced = true;
1737  }
1738 
1739  if (Referenced || D->hasAttr<UnusedAttr>() ||
1740  D->hasAttr<ObjCPreciseLifetimeAttr>())
1741  return false;
1742 
1743  if (isa<LabelDecl>(D))
1744  return true;
1745 
1746  // Except for labels, we only care about unused decls that are local to
1747  // functions.
1748  bool WithinFunction = D->getDeclContext()->isFunctionOrMethod();
1749  if (const auto *R = dyn_cast<CXXRecordDecl>(D->getDeclContext()))
1750  // For dependent types, the diagnostic is deferred.
1751  WithinFunction =
1752  WithinFunction || (R->isLocalClass() && !R->isDependentType());
1753  if (!WithinFunction)
1754  return false;
1755 
1756  if (isa<TypedefNameDecl>(D))
1757  return true;
1758 
1759  // White-list anything that isn't a local variable.
1760  if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D))
1761  return false;
1762 
1763  // Types of valid local variables should be complete, so this should succeed.
1764  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1765 
1766  // White-list anything with an __attribute__((unused)) type.
1767  const auto *Ty = VD->getType().getTypePtr();
1768 
1769  // Only look at the outermost level of typedef.
1770  if (const TypedefType *TT = Ty->getAs<TypedefType>()) {
1771  if (TT->getDecl()->hasAttr<UnusedAttr>())
1772  return false;
1773  }
1774 
1775  // If we failed to complete the type for some reason, or if the type is
1776  // dependent, don't diagnose the variable.
1777  if (Ty->isIncompleteType() || Ty->isDependentType())
1778  return false;
1779 
1780  // Look at the element type to ensure that the warning behaviour is
1781  // consistent for both scalars and arrays.
1782  Ty = Ty->getBaseElementTypeUnsafe();
1783 
1784  if (const TagType *TT = Ty->getAs<TagType>()) {
1785  const TagDecl *Tag = TT->getDecl();
1786  if (Tag->hasAttr<UnusedAttr>())
1787  return false;
1788 
1789  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
1790  if (!RD->hasTrivialDestructor() && !RD->hasAttr<WarnUnusedAttr>())
1791  return false;
1792 
1793  if (const Expr *Init = VD->getInit()) {
1794  if (const ExprWithCleanups *Cleanups =
1795  dyn_cast<ExprWithCleanups>(Init))
1796  Init = Cleanups->getSubExpr();
1797  const CXXConstructExpr *Construct =
1798  dyn_cast<CXXConstructExpr>(Init);
1799  if (Construct && !Construct->isElidable()) {
1800  CXXConstructorDecl *CD = Construct->getConstructor();
1801  if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
1802  (VD->getInit()->isValueDependent() || !VD->evaluateValue()))
1803  return false;
1804  }
1805  }
1806  }
1807  }
1808 
1809  // TODO: __attribute__((unused)) templates?
1810  }
1811 
1812  return true;
1813 }
1814 
1815 static void GenerateFixForUnusedDecl(const NamedDecl *D, ASTContext &Ctx,
1816  FixItHint &Hint) {
1817  if (isa<LabelDecl>(D)) {
1819  D->getEndLoc(), tok::colon, Ctx.getSourceManager(), Ctx.getLangOpts(),
1820  true);
1821  if (AfterColon.isInvalid())
1822  return;
1823  Hint = FixItHint::CreateRemoval(
1824  CharSourceRange::getCharRange(D->getBeginLoc(), AfterColon));
1825  }
1826 }
1827 
1829  if (D->getTypeForDecl()->isDependentType())
1830  return;
1831 
1832  for (auto *TmpD : D->decls()) {
1833  if (const auto *T = dyn_cast<TypedefNameDecl>(TmpD))
1834  DiagnoseUnusedDecl(T);
1835  else if(const auto *R = dyn_cast<RecordDecl>(TmpD))
1836  DiagnoseUnusedNestedTypedefs(R);
1837  }
1838 }
1839 
1840 /// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
1841 /// unless they are marked attr(unused).
1843  if (!ShouldDiagnoseUnusedDecl(D))
1844  return;
1845 
1846  if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
1847  // typedefs can be referenced later on, so the diagnostics are emitted
1848  // at end-of-translation-unit.
1849  UnusedLocalTypedefNameCandidates.insert(TD);
1850  return;
1851  }
1852 
1853  FixItHint Hint;
1854  GenerateFixForUnusedDecl(D, Context, Hint);
1855 
1856  unsigned DiagID;
1857  if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
1858  DiagID = diag::warn_unused_exception_param;
1859  else if (isa<LabelDecl>(D))
1860  DiagID = diag::warn_unused_label;
1861  else
1862  DiagID = diag::warn_unused_variable;
1863 
1864  Diag(D->getLocation(), DiagID) << D << Hint;
1865 }
1866 
1867 static void CheckPoppedLabel(LabelDecl *L, Sema &S) {
1868  // Verify that we have no forward references left. If so, there was a goto
1869  // or address of a label taken, but no definition of it. Label fwd
1870  // definitions are indicated with a null substmt which is also not a resolved
1871  // MS inline assembly label name.
1872  bool Diagnose = false;
1873  if (L->isMSAsmLabel())
1874  Diagnose = !L->isResolvedMSAsmLabel();
1875  else
1876  Diagnose = L->getStmt() == nullptr;
1877  if (Diagnose)
1878  S.Diag(L->getLocation(), diag::err_undeclared_label_use) <<L->getDeclName();
1879 }
1880 
1882  S->mergeNRVOIntoParent();
1883 
1884  if (S->decl_empty()) return;
1885  assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&
1886  "Scope shouldn't contain decls!");
1887 
1888  for (auto *TmpD : S->decls()) {
1889  assert(TmpD && "This decl didn't get pushed??");
1890 
1891  assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?");
1892  NamedDecl *D = cast<NamedDecl>(TmpD);
1893 
1894  // Diagnose unused variables in this scope.
1895  if (!S->hasUnrecoverableErrorOccurred()) {
1896  DiagnoseUnusedDecl(D);
1897  if (const auto *RD = dyn_cast<RecordDecl>(D))
1898  DiagnoseUnusedNestedTypedefs(RD);
1899  }
1900 
1901  if (!D->getDeclName()) continue;
1902 
1903  // If this was a forward reference to a label, verify it was defined.
1904  if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
1905  CheckPoppedLabel(LD, *this);
1906 
1907  // Remove this name from our lexical scope, and warn on it if we haven't
1908  // already.
1909  IdResolver.RemoveDecl(D);
1910  auto ShadowI = ShadowingDecls.find(D);
1911  if (ShadowI != ShadowingDecls.end()) {
1912  if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {
1913  Diag(D->getLocation(), diag::warn_ctor_parm_shadows_field)
1914  << D << FD << FD->getParent();
1915  Diag(FD->getLocation(), diag::note_previous_declaration);
1916  }
1917  ShadowingDecls.erase(ShadowI);
1918  }
1919  }
1920 }
1921 
1922 /// Look for an Objective-C class in the translation unit.
1923 ///
1924 /// \param Id The name of the Objective-C class we're looking for. If
1925 /// typo-correction fixes this name, the Id will be updated
1926 /// to the fixed name.
1927 ///
1928 /// \param IdLoc The location of the name in the translation unit.
1929 ///
1930 /// \param DoTypoCorrection If true, this routine will attempt typo correction
1931 /// if there is no class with the given name.
1932 ///
1933 /// \returns The declaration of the named Objective-C class, or NULL if the
1934 /// class could not be found.
1936  SourceLocation IdLoc,
1937  bool DoTypoCorrection) {
1938  // The third "scope" argument is 0 since we aren't enabling lazy built-in
1939  // creation from this context.
1940  NamedDecl *IDecl = LookupSingleName(TUScope, Id, IdLoc, LookupOrdinaryName);
1941 
1942  if (!IDecl && DoTypoCorrection) {
1943  // Perform typo correction at the given location, but only if we
1944  // find an Objective-C class name.
1946  if (TypoCorrection C =
1947  CorrectTypo(DeclarationNameInfo(Id, IdLoc), LookupOrdinaryName,
1948  TUScope, nullptr, CCC, CTK_ErrorRecovery)) {
1949  diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
1950  IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
1951  Id = IDecl->getIdentifier();
1952  }
1953  }
1954  ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
1955  // This routine must always return a class definition, if any.
1956  if (Def && Def->getDefinition())
1957  Def = Def->getDefinition();
1958  return Def;
1959 }
1960 
1961 /// getNonFieldDeclScope - Retrieves the innermost scope, starting
1962 /// from S, where a non-field would be declared. This routine copes
1963 /// with the difference between C and C++ scoping rules in structs and
1964 /// unions. For example, the following code is well-formed in C but
1965 /// ill-formed in C++:
1966 /// @code
1967 /// struct S6 {
1968 /// enum { BAR } e;
1969 /// };
1970 ///
1971 /// void test_S6() {
1972 /// struct S6 a;
1973 /// a.e = BAR;
1974 /// }
1975 /// @endcode
1976 /// For the declaration of BAR, this routine will return a different
1977 /// scope. The scope S will be the scope of the unnamed enumeration
1978 /// within S6. In C++, this routine will return the scope associated
1979 /// with S6, because the enumeration's scope is a transparent
1980 /// context but structures can contain non-field names. In C, this
1981 /// routine will return the translation unit scope, since the
1982 /// enumeration's scope is a transparent context and structures cannot
1983 /// contain non-field names.
1985  while (((S->getFlags() & Scope::DeclScope) == 0) ||
1986  (S->getEntity() && S->getEntity()->isTransparentContext()) ||
1987  (S->isClassScope() && !getLangOpts().CPlusPlus))
1988  S = S->getParent();
1989  return S;
1990 }
1991 
1992 /// Looks up the declaration of "struct objc_super" and
1993 /// saves it for later use in building builtin declaration of
1994 /// objc_msgSendSuper and objc_msgSendSuper_stret. If no such
1995 /// pre-existing declaration exists no action takes place.
1996 static void LookupPredefedObjCSuperType(Sema &ThisSema, Scope *S,
1997  IdentifierInfo *II) {
1998  if (!II->isStr("objc_msgSendSuper"))
1999  return;
2000  ASTContext &Context = ThisSema.Context;
2001 
2002  LookupResult Result(ThisSema, &Context.Idents.get("objc_super"),
2004  ThisSema.LookupName(Result, S);
2005  if (Result.getResultKind() == LookupResult::Found)
2006  if (const TagDecl *TD = Result.getAsSingle<TagDecl>())
2007  Context.setObjCSuperType(Context.getTagDeclType(TD));
2008 }
2009 
2010 static StringRef getHeaderName(Builtin::Context &BuiltinInfo, unsigned ID,
2012  switch (Error) {
2013  case ASTContext::GE_None:
2014  return "";
2016  return BuiltinInfo.getHeaderName(ID);
2018  return "stdio.h";
2020  return "setjmp.h";
2022  return "ucontext.h";
2023  }
2024  llvm_unreachable("unhandled error kind");
2025 }
2026 
2027 /// LazilyCreateBuiltin - The specified Builtin-ID was first used at
2028 /// file scope. lazily create a decl for it. ForRedeclaration is true
2029 /// if we're creating this built-in in anticipation of redeclaring the
2030 /// built-in.
2032  Scope *S, bool ForRedeclaration,
2033  SourceLocation Loc) {
2034  LookupPredefedObjCSuperType(*this, S, II);
2035 
2037  QualType R = Context.GetBuiltinType(ID, Error);
2038  if (Error) {
2039  if (!ForRedeclaration)
2040  return nullptr;
2041 
2042  // If we have a builtin without an associated type we should not emit a
2043  // warning when we were not able to find a type for it.
2044  if (Error == ASTContext::GE_Missing_type)
2045  return nullptr;
2046 
2047  // If we could not find a type for setjmp it is because the jmp_buf type was
2048  // not defined prior to the setjmp declaration.
2049  if (Error == ASTContext::GE_Missing_setjmp) {
2050  Diag(Loc, diag::warn_implicit_decl_no_jmp_buf)
2051  << Context.BuiltinInfo.getName(ID);
2052  return nullptr;
2053  }
2054 
2055  // Generally, we emit a warning that the declaration requires the
2056  // appropriate header.
2057  Diag(Loc, diag::warn_implicit_decl_requires_sysheader)
2058  << getHeaderName(Context.BuiltinInfo, ID, Error)
2059  << Context.BuiltinInfo.getName(ID);
2060  return nullptr;
2061  }
2062 
2063  if (!ForRedeclaration &&
2064  (Context.BuiltinInfo.isPredefinedLibFunction(ID) ||
2065  Context.BuiltinInfo.isHeaderDependentFunction(ID))) {
2066  Diag(Loc, diag::ext_implicit_lib_function_decl)
2067  << Context.BuiltinInfo.getName(ID) << R;
2068  if (Context.BuiltinInfo.getHeaderName(ID) &&
2069  !Diags.isIgnored(diag::ext_implicit_lib_function_decl, Loc))
2070  Diag(Loc, diag::note_include_header_or_declare)
2071  << Context.BuiltinInfo.getHeaderName(ID)
2072  << Context.BuiltinInfo.getName(ID);
2073  }
2074 
2075  if (R.isNull())
2076  return nullptr;
2077 
2079  if (getLangOpts().CPlusPlus) {
2080  LinkageSpecDecl *CLinkageDecl =
2081  LinkageSpecDecl::Create(Context, Parent, Loc, Loc,
2082  LinkageSpecDecl::lang_c, false);
2083  CLinkageDecl->setImplicit();
2084  Parent->addDecl(CLinkageDecl);
2085  Parent = CLinkageDecl;
2086  }
2087 
2088  FunctionDecl *New = FunctionDecl::Create(Context,
2089  Parent,
2090  Loc, Loc, II, R, /*TInfo=*/nullptr,
2091  SC_Extern,
2092  false,
2093  R->isFunctionProtoType());
2094  New->setImplicit();
2095 
2096  // Create Decl objects for each parameter, adding them to the
2097  // FunctionDecl.
2098  if (const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(R)) {
2100  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
2101  ParmVarDecl *parm =
2103  nullptr, FT->getParamType(i), /*TInfo=*/nullptr,
2104  SC_None, nullptr);
2105  parm->setScopeInfo(0, i);
2106  Params.push_back(parm);
2107  }
2108  New->setParams(Params);
2109  }
2110 
2111  AddKnownFunctionAttributes(New);
2112  RegisterLocallyScopedExternCDecl(New, S);
2113 
2114  // TUScope is the translation-unit scope to insert this function into.
2115  // FIXME: This is hideous. We need to teach PushOnScopeChains to
2116  // relate Scopes to DeclContexts, and probably eliminate CurContext
2117  // entirely, but we're not there yet.
2118  DeclContext *SavedContext = CurContext;
2119  CurContext = Parent;
2120  PushOnScopeChains(New, TUScope);
2121  CurContext = SavedContext;
2122  return New;
2123 }
2124 
2125 /// Typedef declarations don't have linkage, but they still denote the same
2126 /// entity if their types are the same.
2127 /// FIXME: This is notionally doing the same thing as ASTReaderDecl's
2128 /// isSameEntity.
2132  // This is only interesting when modules are enabled.
2133  if (!S.getLangOpts().Modules && !S.getLangOpts().ModulesLocalVisibility)
2134  return;
2135 
2136  // Empty sets are uninteresting.
2137  if (Previous.empty())
2138  return;
2139 
2140  LookupResult::Filter Filter = Previous.makeFilter();
2141  while (Filter.hasNext()) {
2142  NamedDecl *Old = Filter.next();
2143 
2144  // Non-hidden declarations are never ignored.
2145  if (S.isVisible(Old))
2146  continue;
2147 
2148  // Declarations of the same entity are not ignored, even if they have
2149  // different linkages.
2150  if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
2151  if (S.Context.hasSameType(OldTD->getUnderlyingType(),
2152  Decl->getUnderlyingType()))
2153  continue;
2154 
2155  // If both declarations give a tag declaration a typedef name for linkage
2156  // purposes, then they declare the same entity.
2157  if (OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true) &&
2159  continue;
2160  }
2161 
2162  Filter.erase();
2163  }
2164 
2165  Filter.done();
2166 }
2167 
2169  QualType OldType;
2170  if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
2171  OldType = OldTypedef->getUnderlyingType();
2172  else
2173  OldType = Context.getTypeDeclType(Old);
2174  QualType NewType = New->getUnderlyingType();
2175 
2176  if (NewType->isVariablyModifiedType()) {
2177  // Must not redefine a typedef with a variably-modified type.
2178  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
2179  Diag(New->getLocation(), diag::err_redefinition_variably_modified_typedef)
2180  << Kind << NewType;
2181  if (Old->getLocation().isValid())
2182  notePreviousDefinition(Old, New->getLocation());
2183  New->setInvalidDecl();
2184  return true;
2185  }
2186 
2187  if (OldType != NewType &&
2188  !OldType->isDependentType() &&
2189  !NewType->isDependentType() &&
2190  !Context.hasSameType(OldType, NewType)) {
2191  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
2192  Diag(New->getLocation(), diag::err_redefinition_different_typedef)
2193  << Kind << NewType << OldType;
2194  if (Old->getLocation().isValid())
2195  notePreviousDefinition(Old, New->getLocation());
2196  New->setInvalidDecl();
2197  return true;
2198  }
2199  return false;
2200 }
2201 
2202 /// MergeTypedefNameDecl - We just parsed a typedef 'New' which has the
2203 /// same name and scope as a previous declaration 'Old'. Figure out
2204 /// how to resolve this situation, merging decls or emitting
2205 /// diagnostics as appropriate. If there was an error, set New to be invalid.
2206 ///
2208  LookupResult &OldDecls) {
2209  // If the new decl is known invalid already, don't bother doing any
2210  // merging checks.
2211  if (New->isInvalidDecl()) return;
2212 
2213  // Allow multiple definitions for ObjC built-in typedefs.
2214  // FIXME: Verify the underlying types are equivalent!
2215  if (getLangOpts().ObjC) {
2216  const IdentifierInfo *TypeID = New->getIdentifier();
2217  switch (TypeID->getLength()) {
2218  default: break;
2219  case 2:
2220  {
2221  if (!TypeID->isStr("id"))
2222  break;
2223  QualType T = New->getUnderlyingType();
2224  if (!T->isPointerType())
2225  break;
2226  if (!T->isVoidPointerType()) {
2227  QualType PT = T->castAs<PointerType>()->getPointeeType();
2228  if (!PT->isStructureType())
2229  break;
2230  }
2231  Context.setObjCIdRedefinitionType(T);
2232  // Install the built-in type for 'id', ignoring the current definition.
2233  New->setTypeForDecl(Context.getObjCIdType().getTypePtr());
2234  return;
2235  }
2236  case 5:
2237  if (!TypeID->isStr("Class"))
2238  break;
2240  // Install the built-in type for 'Class', ignoring the current definition.
2241  New->setTypeForDecl(Context.getObjCClassType().getTypePtr());
2242  return;
2243  case 3:
2244  if (!TypeID->isStr("SEL"))
2245  break;
2247  // Install the built-in type for 'SEL', ignoring the current definition.
2248  New->setTypeForDecl(Context.getObjCSelType().getTypePtr());
2249  return;
2250  }
2251  // Fall through - the typedef name was not a builtin type.
2252  }
2253 
2254  // Verify the old decl was also a type.
2255  TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
2256  if (!Old) {
2257  Diag(New->getLocation(), diag::err_redefinition_different_kind)
2258  << New->getDeclName();
2259 
2260  NamedDecl *OldD = OldDecls.getRepresentativeDecl();
2261  if (OldD->getLocation().isValid())
2262  notePreviousDefinition(OldD, New->getLocation());
2263 
2264  return New->setInvalidDecl();
2265  }
2266 
2267  // If the old declaration is invalid, just give up here.
2268  if (Old->isInvalidDecl())
2269  return New->setInvalidDecl();
2270 
2271  if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
2272  auto *OldTag = OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
2273  auto *NewTag = New->getAnonDeclWithTypedefName();
2274  NamedDecl *Hidden = nullptr;
2275  if (OldTag && NewTag &&
2276  OldTag->getCanonicalDecl() != NewTag->getCanonicalDecl() &&
2277  !hasVisibleDefinition(OldTag, &Hidden)) {
2278  // There is a definition of this tag, but it is not visible. Use it
2279  // instead of our tag.
2280  New->setTypeForDecl(OldTD->getTypeForDecl());
2281  if (OldTD->isModed())
2282  New->setModedTypeSourceInfo(OldTD->getTypeSourceInfo(),
2283  OldTD->getUnderlyingType());
2284  else
2285  New->setTypeSourceInfo(OldTD->getTypeSourceInfo());
2286 
2287  // Make the old tag definition visible.
2288  makeMergedDefinitionVisible(Hidden);
2289 
2290  // If this was an unscoped enumeration, yank all of its enumerators
2291  // out of the scope.
2292  if (isa<EnumDecl>(NewTag)) {
2293  Scope *EnumScope = getNonFieldDeclScope(S);
2294  for (auto *D : NewTag->decls()) {
2295  auto *ED = cast<EnumConstantDecl>(D);
2296  assert(EnumScope->isDeclScope(ED));
2297  EnumScope->RemoveDecl(ED);
2298  IdResolver.RemoveDecl(ED);
2299  ED->getLexicalDeclContext()->removeDecl(ED);
2300  }
2301  }
2302  }
2303  }
2304 
2305  // If the typedef types are not identical, reject them in all languages and
2306  // with any extensions enabled.
2307  if (isIncompatibleTypedef(Old, New))
2308  return;
2309 
2310  // The types match. Link up the redeclaration chain and merge attributes if
2311  // the old declaration was a typedef.
2312  if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Old)) {
2313  New->setPreviousDecl(Typedef);
2314  mergeDeclAttributes(New, Old);
2315  }
2316 
2317  if (getLangOpts().MicrosoftExt)
2318  return;
2319 
2320  if (getLangOpts().CPlusPlus) {
2321  // C++ [dcl.typedef]p2:
2322  // In a given non-class scope, a typedef specifier can be used to
2323  // redefine the name of any type declared in that scope to refer
2324  // to the type to which it already refers.
2325  if (!isa<CXXRecordDecl>(CurContext))
2326  return;
2327 
2328  // C++0x [dcl.typedef]p4:
2329  // In a given class scope, a typedef specifier can be used to redefine
2330  // any class-name declared in that scope that is not also a typedef-name
2331  // to refer to the type to which it already refers.
2332  //
2333  // This wording came in via DR424, which was a correction to the
2334  // wording in DR56, which accidentally banned code like:
2335  //
2336  // struct S {
2337  // typedef struct A { } A;
2338  // };
2339  //
2340  // in the C++03 standard. We implement the C++0x semantics, which
2341  // allow the above but disallow
2342  //
2343  // struct S {
2344  // typedef int I;
2345  // typedef int I;
2346  // };
2347  //
2348  // since that was the intent of DR56.
2349  if (!isa<TypedefNameDecl>(Old))
2350  return;
2351 
2352  Diag(New->getLocation(), diag::err_redefinition)
2353  << New->getDeclName();
2354  notePreviousDefinition(Old, New->getLocation());
2355  return New->setInvalidDecl();
2356  }
2357 
2358  // Modules always permit redefinition of typedefs, as does C11.
2359  if (getLangOpts().Modules || getLangOpts().C11)
2360  return;
2361 
2362  // If we have a redefinition of a typedef in C, emit a warning. This warning
2363  // is normally mapped to an error, but can be controlled with
2364  // -Wtypedef-redefinition. If either the original or the redefinition is
2365  // in a system header, don't emit this for compatibility with GCC.
2366  if (getDiagnostics().getSuppressSystemWarnings() &&
2367  // Some standard types are defined implicitly in Clang (e.g. OpenCL).
2368  (Old->isImplicit() ||
2369  Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
2370  Context.getSourceManager().isInSystemHeader(New->getLocation())))
2371  return;
2372 
2373  Diag(New->getLocation(), diag::ext_redefinition_of_typedef)
2374  << New->getDeclName();
2375  notePreviousDefinition(Old, New->getLocation());
2376 }
2377 
2378 /// DeclhasAttr - returns true if decl Declaration already has the target
2379 /// attribute.
2380 static bool DeclHasAttr(const Decl *D, const Attr *A) {
2381  const OwnershipAttr *OA = dyn_cast<OwnershipAttr>(A);
2382  const AnnotateAttr *Ann = dyn_cast<AnnotateAttr>(A);
2383  for (const auto *i : D->attrs())
2384  if (i->getKind() == A->getKind()) {
2385  if (Ann) {
2386  if (Ann->getAnnotation() == cast<AnnotateAttr>(i)->getAnnotation())
2387  return true;
2388  continue;
2389  }
2390  // FIXME: Don't hardcode this check
2391  if (OA && isa<OwnershipAttr>(i))
2392  return OA->getOwnKind() == cast<OwnershipAttr>(i)->getOwnKind();
2393  return true;
2394  }
2395 
2396  return false;
2397 }
2398 
2400  if (VarDecl *VD = dyn_cast<VarDecl>(D))
2401  return VD->isThisDeclarationADefinition();
2402  if (TagDecl *TD = dyn_cast<TagDecl>(D))
2403  return TD->isCompleteDefinition() || TD->isBeingDefined();
2404  return true;
2405 }
2406 
2407 /// Merge alignment attributes from \p Old to \p New, taking into account the
2408 /// special semantics of C11's _Alignas specifier and C++11's alignas attribute.
2409 ///
2410 /// \return \c true if any attributes were added to \p New.
2411 static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
2412  // Look for alignas attributes on Old, and pick out whichever attribute
2413  // specifies the strictest alignment requirement.
2414  AlignedAttr *OldAlignasAttr = nullptr;
2415  AlignedAttr *OldStrictestAlignAttr = nullptr;
2416  unsigned OldAlign = 0;
2417  for (auto *I : Old->specific_attrs<AlignedAttr>()) {
2418  // FIXME: We have no way of representing inherited dependent alignments
2419  // in a case like:
2420  // template<int A, int B> struct alignas(A) X;
2421  // template<int A, int B> struct alignas(B) X {};
2422  // For now, we just ignore any alignas attributes which are not on the
2423  // definition in such a case.
2424  if (I->isAlignmentDependent())
2425  return false;
2426 
2427  if (I->isAlignas())
2428  OldAlignasAttr = I;
2429 
2430  unsigned Align = I->getAlignment(S.Context);
2431  if (Align > OldAlign) {
2432  OldAlign = Align;
2433  OldStrictestAlignAttr = I;
2434  }
2435  }
2436 
2437  // Look for alignas attributes on New.
2438  AlignedAttr *NewAlignasAttr = nullptr;
2439  unsigned NewAlign = 0;
2440  for (auto *I : New->specific_attrs<AlignedAttr>()) {
2441  if (I->isAlignmentDependent())
2442  return false;
2443 
2444  if (I->isAlignas())
2445  NewAlignasAttr = I;
2446 
2447  unsigned Align = I->getAlignment(S.Context);
2448  if (Align > NewAlign)
2449  NewAlign = Align;
2450  }
2451 
2452  if (OldAlignasAttr && NewAlignasAttr && OldAlign != NewAlign) {
2453  // Both declarations have 'alignas' attributes. We require them to match.
2454  // C++11 [dcl.align]p6 and C11 6.7.5/7 both come close to saying this, but
2455  // fall short. (If two declarations both have alignas, they must both match
2456  // every definition, and so must match each other if there is a definition.)
2457 
2458  // If either declaration only contains 'alignas(0)' specifiers, then it
2459  // specifies the natural alignment for the type.
2460  if (OldAlign == 0 || NewAlign == 0) {
2461  QualType Ty;
2462  if (ValueDecl *VD = dyn_cast<ValueDecl>(New))
2463  Ty = VD->getType();
2464  else
2465  Ty = S.Context.getTagDeclType(cast<TagDecl>(New));
2466 
2467  if (OldAlign == 0)
2468  OldAlign = S.Context.getTypeAlign(Ty);
2469  if (NewAlign == 0)
2470  NewAlign = S.Context.getTypeAlign(Ty);
2471  }
2472 
2473  if (OldAlign != NewAlign) {
2474  S.Diag(NewAlignasAttr->getLocation(), diag::err_alignas_mismatch)
2475  << (unsigned)S.Context.toCharUnitsFromBits(OldAlign).getQuantity()
2476  << (unsigned)S.Context.toCharUnitsFromBits(NewAlign).getQuantity();
2477  S.Diag(OldAlignasAttr->getLocation(), diag::note_previous_declaration);
2478  }
2479  }
2480 
2481  if (OldAlignasAttr && !NewAlignasAttr && isAttributeTargetADefinition(New)) {
2482  // C++11 [dcl.align]p6:
2483  // if any declaration of an entity has an alignment-specifier,
2484  // every defining declaration of that entity shall specify an
2485  // equivalent alignment.
2486  // C11 6.7.5/7:
2487  // If the definition of an object does not have an alignment
2488  // specifier, any other declaration of that object shall also
2489  // have no alignment specifier.
2490  S.Diag(New->getLocation(), diag::err_alignas_missing_on_definition)
2491  << OldAlignasAttr;
2492  S.Diag(OldAlignasAttr->getLocation(), diag::note_alignas_on_declaration)
2493  << OldAlignasAttr;
2494  }
2495 
2496  bool AnyAdded = false;
2497 
2498  // Ensure we have an attribute representing the strictest alignment.
2499  if (OldAlign > NewAlign) {
2500  AlignedAttr *Clone = OldStrictestAlignAttr->clone(S.Context);
2501  Clone->setInherited(true);
2502  New->addAttr(Clone);
2503  AnyAdded = true;
2504  }
2505 
2506  // Ensure we have an alignas attribute if the old declaration had one.
2507  if (OldAlignasAttr && !NewAlignasAttr &&
2508  !(AnyAdded && OldStrictestAlignAttr->isAlignas())) {
2509  AlignedAttr *Clone = OldAlignasAttr->clone(S.Context);
2510  Clone->setInherited(true);
2511  New->addAttr(Clone);
2512  AnyAdded = true;
2513  }
2514 
2515  return AnyAdded;
2516 }
2517 
2518 static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
2519  const InheritableAttr *Attr,
2521  // This function copies an attribute Attr from a previous declaration to the
2522  // new declaration D if the new declaration doesn't itself have that attribute
2523  // yet or if that attribute allows duplicates.
2524  // If you're adding a new attribute that requires logic different from
2525  // "use explicit attribute on decl if present, else use attribute from
2526  // previous decl", for example if the attribute needs to be consistent
2527  // between redeclarations, you need to call a custom merge function here.
2528  InheritableAttr *NewAttr = nullptr;
2529  if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
2530  NewAttr = S.mergeAvailabilityAttr(
2531  D, *AA, AA->getPlatform(), AA->isImplicit(), AA->getIntroduced(),
2532  AA->getDeprecated(), AA->getObsoleted(), AA->getUnavailable(),
2533  AA->getMessage(), AA->getStrict(), AA->getReplacement(), AMK,
2534  AA->getPriority());
2535  else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
2536  NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility());
2537  else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr))
2538  NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility());
2539  else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr))
2540  NewAttr = S.mergeDLLImportAttr(D, *ImportA);
2541  else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr))
2542  NewAttr = S.mergeDLLExportAttr(D, *ExportA);
2543  else if (const auto *FA = dyn_cast<FormatAttr>(Attr))
2544  NewAttr = S.mergeFormatAttr(D, *FA, FA->getType(), FA->getFormatIdx(),
2545  FA->getFirstArg());
2546  else if (const auto *SA = dyn_cast<SectionAttr>(Attr))
2547  NewAttr = S.mergeSectionAttr(D, *SA, SA->getName());
2548  else if (const auto *CSA = dyn_cast<CodeSegAttr>(Attr))
2549  NewAttr = S.mergeCodeSegAttr(D, *CSA, CSA->getName());
2550  else if (const auto *IA = dyn_cast<MSInheritanceAttr>(Attr))
2551  NewAttr = S.mergeMSInheritanceAttr(D, *IA, IA->getBestCase(),
2552  IA->getSemanticSpelling());
2553  else if (const auto *AA = dyn_cast<AlwaysInlineAttr>(Attr))
2554  NewAttr = S.mergeAlwaysInlineAttr(D, *AA,
2555  &S.Context.Idents.get(AA->getSpelling()));
2556  else if (S.getLangOpts().CUDA && isa<FunctionDecl>(D) &&
2557  (isa<CUDAHostAttr>(Attr) || isa<CUDADeviceAttr>(Attr) ||
2558  isa<CUDAGlobalAttr>(Attr))) {
2559  // CUDA target attributes are part of function signature for
2560  // overloading purposes and must not be merged.
2561  return false;
2562  } else if (const auto *MA = dyn_cast<MinSizeAttr>(Attr))
2563  NewAttr = S.mergeMinSizeAttr(D, *MA);
2564  else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
2565  NewAttr = S.mergeOptimizeNoneAttr(D, *OA);
2566  else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
2567  NewAttr = S.mergeInternalLinkageAttr(D, *InternalLinkageA);
2568  else if (const auto *CommonA = dyn_cast<CommonAttr>(Attr))
2569  NewAttr = S.mergeCommonAttr(D, *CommonA);
2570  else if (isa<AlignedAttr>(Attr))
2571  // AlignedAttrs are handled separately, because we need to handle all
2572  // such attributes on a declaration at the same time.
2573  NewAttr = nullptr;
2574  else if ((isa<DeprecatedAttr>(Attr) || isa<UnavailableAttr>(Attr)) &&
2575  (AMK == Sema::AMK_Override ||
2577  NewAttr = nullptr;
2578  else if (const auto *UA = dyn_cast<UuidAttr>(Attr))
2579  NewAttr = S.mergeUuidAttr(D, *UA, UA->getGuid());
2580  else if (const auto *SLHA = dyn_cast<SpeculativeLoadHardeningAttr>(Attr))
2581  NewAttr = S.mergeSpeculativeLoadHardeningAttr(D, *SLHA);
2582  else if (const auto *SLHA = dyn_cast<NoSpeculativeLoadHardeningAttr>(Attr))
2583  NewAttr = S.mergeNoSpeculativeLoadHardeningAttr(D, *SLHA);
2584  else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
2585  NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
2586 
2587  if (NewAttr) {
2588  NewAttr->setInherited(true);
2589  D->addAttr(NewAttr);
2590  if (isa<MSInheritanceAttr>(NewAttr))
2591  S.Consumer.AssignInheritanceModel(cast<CXXRecordDecl>(D));
2592  return true;
2593  }
2594 
2595  return false;
2596 }
2597 
2598 static const NamedDecl *getDefinition(const Decl *D) {
2599  if (const TagDecl *TD = dyn_cast<TagDecl>(D))
2600  return TD->getDefinition();
2601  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
2602  const VarDecl *Def = VD->getDefinition();
2603  if (Def)
2604  return Def;
2605  return VD->getActingDefinition();
2606  }
2607  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
2608  return FD->getDefinition();
2609  return nullptr;
2610 }
2611 
2612 static bool hasAttribute(const Decl *D, attr::Kind Kind) {
2613  for (const auto *Attribute : D->attrs())
2614  if (Attribute->getKind() == Kind)
2615  return true;
2616  return false;
2617 }
2618 
2619 /// checkNewAttributesAfterDef - If we already have a definition, check that
2620 /// there are no new attributes in this declaration.
2621 static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
2622  if (!New->hasAttrs())
2623  return;
2624 
2625  const NamedDecl *Def = getDefinition(Old);
2626  if (!Def || Def == New)
2627  return;
2628 
2629  AttrVec &NewAttributes = New->getAttrs();
2630  for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
2631  const Attr *NewAttribute = NewAttributes[I];
2632 
2633  if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
2634  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
2635  Sema::SkipBodyInfo SkipBody;
2636  S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);
2637 
2638  // If we're skipping this definition, drop the "alias" attribute.
2639  if (SkipBody.ShouldSkip) {
2640  NewAttributes.erase(NewAttributes.begin() + I);
2641  --E;
2642  continue;
2643  }
2644  } else {
2645  VarDecl *VD = cast<VarDecl>(New);
2646  unsigned Diag = cast<VarDecl>(Def)->isThisDeclarationADefinition() ==
2648  ? diag::err_alias_after_tentative
2649  : diag::err_redefinition;
2650  S.Diag(VD->getLocation(), Diag) << VD->getDeclName();
2651  if (Diag == diag::err_redefinition)
2652  S.notePreviousDefinition(Def, VD->getLocation());
2653  else
2654  S.Diag(Def->getLocation(), diag::note_previous_definition);
2655  VD->setInvalidDecl();
2656  }
2657  ++I;
2658  continue;
2659  }
2660 
2661  if (const VarDecl *VD = dyn_cast<VarDecl>(Def)) {
2662  // Tentative definitions are only interesting for the alias check above.
2663  if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
2664  ++I;
2665  continue;
2666  }
2667  }
2668 
2669  if (hasAttribute(Def, NewAttribute->getKind())) {
2670  ++I;
2671  continue; // regular attr merging will take care of validating this.
2672  }
2673 
2674  if (isa<C11NoReturnAttr>(NewAttribute)) {
2675  // C's _Noreturn is allowed to be added to a function after it is defined.
2676  ++I;
2677  continue;
2678  } else if (const AlignedAttr *AA = dyn_cast<AlignedAttr>(NewAttribute)) {
2679  if (AA->isAlignas()) {
2680  // C++11 [dcl.align]p6:
2681  // if any declaration of an entity has an alignment-specifier,
2682  // every defining declaration of that entity shall specify an
2683  // equivalent alignment.
2684  // C11 6.7.5/7:
2685  // If the definition of an object does not have an alignment
2686  // specifier, any other declaration of that object shall also
2687  // have no alignment specifier.
2688  S.Diag(Def->getLocation(), diag::err_alignas_missing_on_definition)
2689  << AA;
2690  S.Diag(NewAttribute->getLocation(), diag::note_alignas_on_declaration)
2691  << AA;
2692  NewAttributes.erase(NewAttributes.begin() + I);
2693  --E;
2694  continue;
2695  }
2696  } else if (isa<SelectAnyAttr>(NewAttribute) &&
2697  cast<VarDecl>(New)->isInline() &&
2698  !cast<VarDecl>(New)->isInlineSpecified()) {
2699  // Don't warn about applying selectany to implicitly inline variables.
2700  // Older compilers and language modes would require the use of selectany
2701  // to make such variables inline, and it would have no effect if we
2702  // honored it.
2703  ++I;
2704  continue;
2705  }
2706 
2707  S.Diag(NewAttribute->getLocation(),
2708  diag::warn_attribute_precede_definition);
2709  S.Diag(Def->getLocation(), diag::note_previous_definition);
2710  NewAttributes.erase(NewAttributes.begin() + I);
2711  --E;
2712  }
2713 }
2714 
2715 static void diagnoseMissingConstinit(Sema &S, const VarDecl *InitDecl,
2716  const ConstInitAttr *CIAttr,
2717  bool AttrBeforeInit) {
2718  SourceLocation InsertLoc = InitDecl->getInnerLocStart();
2719 
2720  // Figure out a good way to write this specifier on the old declaration.
2721  // FIXME: We should just use the spelling of CIAttr, but we don't preserve
2722  // enough of the attribute list spelling information to extract that without
2723  // heroics.
2724  std::string SuitableSpelling;
2725  if (S.getLangOpts().CPlusPlus2a)
2726  SuitableSpelling =
2727  S.PP.getLastMacroWithSpelling(InsertLoc, {tok::kw_constinit});
2728  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
2729  SuitableSpelling = S.PP.getLastMacroWithSpelling(
2730  InsertLoc,
2731  {tok::l_square, tok::l_square, S.PP.getIdentifierInfo("clang"),
2732  tok::coloncolon,
2733  S.PP.getIdentifierInfo("require_constant_initialization"),
2734  tok::r_square, tok::r_square});
2735  if (SuitableSpelling.empty())
2736  SuitableSpelling = S.PP.getLastMacroWithSpelling(
2737  InsertLoc,
2738  {tok::kw___attribute, tok::l_paren, tok::r_paren,
2739  S.PP.getIdentifierInfo("require_constant_initialization"),
2740  tok::r_paren, tok::r_paren});
2741  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus2a)
2742  SuitableSpelling = "constinit";
2743  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
2744  SuitableSpelling = "[[clang::require_constant_initialization]]";
2745  if (SuitableSpelling.empty())
2746  SuitableSpelling = "__attribute__((require_constant_initialization))";
2747  SuitableSpelling += " ";
2748 
2749  if (AttrBeforeInit) {
2750  // extern constinit int a;
2751  // int a = 0; // error (missing 'constinit'), accepted as extension
2752  assert(CIAttr->isConstinit() && "should not diagnose this for attribute");
2753  S.Diag(InitDecl->getLocation(), diag::ext_constinit_missing)
2754  << InitDecl << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
2755  S.Diag(CIAttr->getLocation(), diag::note_constinit_specified_here);
2756  } else {
2757  // int a = 0;
2758  // constinit extern int a; // error (missing 'constinit')
2759  S.Diag(CIAttr->getLocation(),
2760  CIAttr->isConstinit() ? diag::err_constinit_added_too_late
2761  : diag::warn_require_const_init_added_too_late)
2762  << FixItHint::CreateRemoval(SourceRange(CIAttr->getLocation()));
2763  S.Diag(InitDecl->getLocation(), diag::note_constinit_missing_here)
2764  << CIAttr->isConstinit()
2765  << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
2766  }
2767 }
2768 
2769 /// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
2771  AvailabilityMergeKind AMK) {
2772  if (UsedAttr *OldAttr = Old->getMostRecentDecl()->getAttr<UsedAttr>()) {
2773  UsedAttr *NewAttr = OldAttr->clone(Context);
2774  NewAttr->setInherited(true);
2775  New->addAttr(NewAttr);
2776  }
2777 
2778  if (!Old->hasAttrs() && !New->hasAttrs())
2779  return;
2780 
2781  // [dcl.constinit]p1:
2782  // If the [constinit] specifier is applied to any declaration of a
2783  // variable, it shall be applied to the initializing declaration.
2784  const auto *OldConstInit = Old->getAttr<ConstInitAttr>();
2785  const auto *NewConstInit = New->getAttr<ConstInitAttr>();
2786  if (bool(OldConstInit) != bool(NewConstInit)) {
2787  const auto *OldVD = cast<VarDecl>(Old);
2788  auto *NewVD = cast<VarDecl>(New);
2789 
2790  // Find the initializing declaration. Note that we might not have linked
2791  // the new declaration into the redeclaration chain yet.
2792  const VarDecl *InitDecl = OldVD->getInitializingDeclaration();
2793  if (!InitDecl &&
2794  (NewVD->hasInit() || NewVD->isThisDeclarationADefinition()))
2795  InitDecl = NewVD;
2796 
2797  if (InitDecl == NewVD) {
2798  // This is the initializing declaration. If it would inherit 'constinit',
2799  // that's ill-formed. (Note that we do not apply this to the attribute
2800  // form).
2801  if (OldConstInit && OldConstInit->isConstinit())
2802  diagnoseMissingConstinit(*this, NewVD, OldConstInit,
2803  /*AttrBeforeInit=*/true);
2804  } else if (NewConstInit) {
2805  // This is the first time we've been told that this declaration should
2806  // have a constant initializer. If we already saw the initializing
2807  // declaration, this is too late.
2808  if (InitDecl && InitDecl != NewVD) {
2809  diagnoseMissingConstinit(*this, InitDecl, NewConstInit,
2810  /*AttrBeforeInit=*/false);
2811  NewVD->dropAttr<ConstInitAttr>();
2812  }
2813  }
2814  }
2815 
2816  // Attributes declared post-definition are currently ignored.
2817  checkNewAttributesAfterDef(*this, New, Old);
2818 
2819  if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
2820  if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
2821  if (!OldA->isEquivalent(NewA)) {
2822  // This redeclaration changes __asm__ label.
2823  Diag(New->getLocation(), diag::err_different_asm_label);
2824  Diag(OldA->getLocation(), diag::note_previous_declaration);
2825  }
2826  } else if (Old->isUsed()) {
2827  // This redeclaration adds an __asm__ label to a declaration that has
2828  // already been ODR-used.
2829  Diag(New->getLocation(), diag::err_late_asm_label_name)
2830  << isa<FunctionDecl>(Old) << New->getAttr<AsmLabelAttr>()->getRange();
2831  }
2832  }
2833 
2834  // Re-declaration cannot add abi_tag's.
2835  if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) {
2836  if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) {
2837  for (const auto &NewTag : NewAbiTagAttr->tags()) {
2838  if (std::find(OldAbiTagAttr->tags_begin(), OldAbiTagAttr->tags_end(),
2839  NewTag) == OldAbiTagAttr->tags_end()) {
2840  Diag(NewAbiTagAttr->getLocation(),
2841  diag::err_new_abi_tag_on_redeclaration)
2842  << NewTag;
2843  Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration);
2844  }
2845  }
2846  } else {
2847  Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration);
2848  Diag(Old->getLocation(), diag::note_previous_declaration);
2849  }
2850  }
2851 
2852  // This redeclaration adds a section attribute.
2853  if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
2854  if (auto *VD = dyn_cast<VarDecl>(New)) {
2855  if (VD->isThisDeclarationADefinition() == VarDecl::DeclarationOnly) {
2856  Diag(New->getLocation(), diag::warn_attribute_section_on_redeclaration);
2857  Diag(Old->getLocation(), diag::note_previous_declaration);
2858  }
2859  }
2860  }
2861 
2862  // Redeclaration adds code-seg attribute.
2863  const auto *NewCSA = New->getAttr<CodeSegAttr>();
2864  if (NewCSA && !Old->hasAttr<CodeSegAttr>() &&
2865  !NewCSA->isImplicit() && isa<CXXMethodDecl>(New)) {
2866  Diag(New->getLocation(), diag::warn_mismatched_section)
2867  << 0 /*codeseg*/;
2868  Diag(Old->getLocation(), diag::note_previous_declaration);
2869  }
2870 
2871  if (!Old->hasAttrs())
2872  return;
2873 
2874  bool foundAny = New->hasAttrs();
2875 
2876  // Ensure that any moving of objects within the allocated map is done before
2877  // we process them.
2878  if (!foundAny) New->setAttrs(AttrVec());
2879 
2880  for (auto *I : Old->specific_attrs<InheritableAttr>()) {
2881  // Ignore deprecated/unavailable/availability attributes if requested.
2882  AvailabilityMergeKind LocalAMK = AMK_None;
2883  if (isa<DeprecatedAttr>(I) ||
2884  isa<UnavailableAttr>(I) ||
2885  isa<AvailabilityAttr>(I)) {
2886  switch (AMK) {
2887  case AMK_None:
2888  continue;
2889 
2890  case AMK_Redeclaration:
2891  case AMK_Override:
2892  case AMK_ProtocolImplementation:
2893  LocalAMK = AMK;
2894  break;
2895  }
2896  }
2897 
2898  // Already handled.
2899  if (isa<UsedAttr>(I))
2900  continue;
2901 
2902  if (mergeDeclAttribute(*this, New, I, LocalAMK))
2903  foundAny = true;
2904  }
2905 
2906  if (mergeAlignedAttrs(*this, New, Old))
2907  foundAny = true;
2908 
2909  if (!foundAny) New->dropAttrs();
2910 }
2911 
2912 /// mergeParamDeclAttributes - Copy attributes from the old parameter
2913 /// to the new one.
2915  const ParmVarDecl *oldDecl,
2916  Sema &S) {
2917  // C++11 [dcl.attr.depend]p2:
2918  // The first declaration of a function shall specify the
2919  // carries_dependency attribute for its declarator-id if any declaration
2920  // of the function specifies the carries_dependency attribute.
2921  const CarriesDependencyAttr *CDA = newDecl->getAttr<CarriesDependencyAttr>();
2922  if (CDA && !oldDecl->hasAttr<CarriesDependencyAttr>()) {
2923  S.Diag(CDA->getLocation(),
2924  diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
2925  // Find the first declaration of the parameter.
2926  // FIXME: Should we build redeclaration chains for function parameters?
2927  const FunctionDecl *FirstFD =
2928  cast<FunctionDecl>(oldDecl->getDeclContext())->getFirstDecl();
2929  const ParmVarDecl *FirstVD =
2930  FirstFD->getParamDecl(oldDecl->getFunctionScopeIndex());
2931  S.Diag(FirstVD->getLocation(),
2932  diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
2933  }
2934 
2935  if (!oldDecl->hasAttrs())
2936  return;
2937 
2938  bool foundAny = newDecl->hasAttrs();
2939 
2940  // Ensure that any moving of objects within the allocated map is
2941  // done before we process them.
2942  if (!foundAny) newDecl->setAttrs(AttrVec());
2943 
2944  for (const auto *I : oldDecl->specific_attrs<InheritableParamAttr>()) {
2945  if (!DeclHasAttr(newDecl, I)) {
2946  InheritableAttr *newAttr =
2947  cast<InheritableParamAttr>(I->clone(S.Context));
2948  newAttr->setInherited(true);
2949  newDecl->addAttr(newAttr);
2950  foundAny = true;
2951  }
2952  }
2953 
2954  if (!foundAny) newDecl->dropAttrs();
2955 }
2956 
2957 static void mergeParamDeclTypes(ParmVarDecl *NewParam,
2958  const ParmVarDecl *OldParam,
2959  Sema &S) {
2960  if (auto Oldnullability = OldParam->getType()->getNullability(S.Context)) {
2961  if (auto Newnullability = NewParam->getType()->getNullability(S.Context)) {
2962  if (*Oldnullability != *Newnullability) {
2963  S.Diag(NewParam->getLocation(), diag::warn_mismatched_nullability_attr)
2965  *Newnullability,
2967  != 0))
2969  *Oldnullability,
2971  != 0));
2972  S.Diag(OldParam->getLocation(), diag::note_previous_declaration);
2973  }
2974  } else {
2975  QualType NewT = NewParam->getType();
2976  NewT = S.Context.getAttributedType(
2977  AttributedType::getNullabilityAttrKind(*Oldnullability),
2978  NewT, NewT);
2979  NewParam->setType(NewT);
2980  }
2981  }
2982 }
2983 
2984 namespace {
2985 
2986 /// Used in MergeFunctionDecl to keep track of function parameters in
2987 /// C.
2988 struct GNUCompatibleParamWarning {
2989  ParmVarDecl *OldParm;
2990  ParmVarDecl *NewParm;
2991  QualType PromotedType;
2992 };
2993 
2994 } // end anonymous namespace
2995 
2996 /// getSpecialMember - get the special member enum for a method.
2998  if (const CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(MD)) {
2999  if (Ctor->isDefaultConstructor())
3001 
3002  if (Ctor->isCopyConstructor())
3003  return Sema::CXXCopyConstructor;
3004 
3005  if (Ctor->isMoveConstructor())
3006  return Sema::CXXMoveConstructor;
3007  } else if (isa<CXXDestructorDecl>(MD)) {
3008  return Sema::CXXDestructor;
3009  } else if (MD->isCopyAssignmentOperator()) {
3010  return Sema::CXXCopyAssignment;
3011  } else if (MD->isMoveAssignmentOperator()) {
3012  return Sema::CXXMoveAssignment;
3013  }
3014 
3015  return Sema::CXXInvalid;
3016 }
3017 
3018 // Determine whether the previous declaration was a definition, implicit
3019 // declaration, or a declaration.
3020 template <typename T>
3021 static std::pair<diag::kind, SourceLocation>
3022 getNoteDiagForInvalidRedeclaration(const T *Old, const T *New) {
3023  diag::kind PrevDiag;
3024  SourceLocation OldLocation = Old->getLocation();
3025  if (Old->isThisDeclarationADefinition())
3026  PrevDiag = diag::note_previous_definition;
3027  else if (Old->isImplicit()) {
3028  PrevDiag = diag::note_previous_implicit_declaration;
3029  if (OldLocation.isInvalid())
3030  OldLocation = New->getLocation();
3031  } else
3032  PrevDiag = diag::note_previous_declaration;
3033  return std::make_pair(PrevDiag, OldLocation);
3034 }
3035 
3036 /// canRedefineFunction - checks if a function can be redefined. Currently,
3037 /// only extern inline functions can be redefined, and even then only in
3038 /// GNU89 mode.
3039 static bool canRedefineFunction(const FunctionDecl *FD,
3040  const LangOptions& LangOpts) {
3041  return ((FD->hasAttr<GNUInlineAttr>() || LangOpts.GNUInline) &&
3042  !LangOpts.CPlusPlus &&
3043  FD->isInlineSpecified() &&
3044  FD->getStorageClass() == SC_Extern);
3045 }
3046 
3048  const AttributedType *AT = T->getAs<AttributedType>();
3049  while (AT && !AT->isCallingConv())
3050  AT = AT->getModifiedType()->getAs<AttributedType>();
3051  return AT;
3052 }
3053 
3054 template <typename T>
3055 static bool haveIncompatibleLanguageLinkages(const T *Old, const T *New) {
3056  const DeclContext *DC = Old->getDeclContext();
3057  if (DC->isRecord())
3058  return false;
3059 
3060  LanguageLinkage OldLinkage = Old->getLanguageLinkage();
3061  if (OldLinkage == CXXLanguageLinkage && New->isInExternCContext())
3062  return true;
3063  if (OldLinkage == CLanguageLinkage && New->isInExternCXXContext())
3064  return true;
3065  return false;
3066 }
3067 
3068 template<typename T> static bool isExternC(T *D) { return D->isExternC(); }
3069 static bool isExternC(VarTemplateDecl *) { return false; }
3070 
3071 /// Check whether a redeclaration of an entity introduced by a
3072 /// using-declaration is valid, given that we know it's not an overload
3073 /// (nor a hidden tag declaration).
3074 template<typename ExpectedDecl>
3076  ExpectedDecl *New) {
3077  // C++11 [basic.scope.declarative]p4:
3078  // Given a set of declarations in a single declarative region, each of
3079  // which specifies the same unqualified name,
3080  // -- they shall all refer to the same entity, or all refer to functions
3081  // and function templates; or
3082  // -- exactly one declaration shall declare a class name or enumeration
3083  // name that is not a typedef name and the other declarations shall all
3084  // refer to the same variable or enumerator, or all refer to functions
3085  // and function templates; in this case the class name or enumeration
3086  // name is hidden (3.3.10).
3087 
3088  // C++11 [namespace.udecl]p14:
3089  // If a function declaration in namespace scope or block scope has the
3090  // same name and the same parameter-type-list as a function introduced
3091  // by a using-declaration, and the declarations do not declare the same
3092  // function, the program is ill-formed.
3093 
3094  auto *Old = dyn_cast<ExpectedDecl>(OldS->getTargetDecl());
3095  if (Old &&
3096  !Old->getDeclContext()->getRedeclContext()->Equals(
3097  New->getDeclContext()->getRedeclContext()) &&
3098  !(isExternC(Old) && isExternC(New)))
3099  Old = nullptr;
3100 
3101  if (!Old) {
3102  S.Diag(New->getLocation(), diag::err_using_decl_conflict_reverse);
3103  S.Diag(OldS->getTargetDecl()->getLocation(), diag::note_using_decl_target);
3104  S.Diag(OldS->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
3105  return true;
3106  }
3107  return false;
3108 }
3109 
3111  const FunctionDecl *B) {
3112  assert(A->getNumParams() == B->getNumParams());
3113 
3114  auto AttrEq = [](const ParmVarDecl *A, const ParmVarDecl *B) {
3115  const auto *AttrA = A->getAttr<PassObjectSizeAttr>();
3116  const auto *AttrB = B->getAttr<PassObjectSizeAttr>();
3117  if (AttrA == AttrB)
3118  return true;
3119  return AttrA && AttrB && AttrA->getType() == AttrB->getType() &&
3120  AttrA->isDynamic() == AttrB->isDynamic();
3121  };
3122 
3123  return std::equal(A->param_begin(), A->param_end(), B->param_begin(), AttrEq);
3124 }
3125 
3126 /// If necessary, adjust the semantic declaration context for a qualified
3127 /// declaration to name the correct inline namespace within the qualifier.
3129  DeclaratorDecl *OldD) {
3130  // The only case where we need to update the DeclContext is when
3131  // redeclaration lookup for a qualified name finds a declaration
3132  // in an inline namespace within the context named by the qualifier:
3133  //
3134  // inline namespace N { int f(); }
3135  // int ::f(); // Sema DC needs adjusting from :: to N::.
3136  //
3137  // For unqualified declarations, the semantic context *can* change
3138  // along the redeclaration chain (for local extern declarations,
3139  // extern "C" declarations, and friend declarations in particular).
3140  if (!NewD->getQualifier())
3141  return;
3142 
3143  // NewD is probably already in the right context.
3144  auto *NamedDC = NewD->getDeclContext()->getRedeclContext();
3145  auto *SemaDC = OldD->getDeclContext()->getRedeclContext();
3146  if (NamedDC->Equals(SemaDC))
3147  return;
3148 
3149  assert((NamedDC->InEnclosingNamespaceSetOf(SemaDC) ||
3150  NewD->isInvalidDecl() || OldD->isInvalidDecl()) &&
3151  "unexpected context for redeclaration");
3152 
3153  auto *LexDC = NewD->getLexicalDeclContext();
3154  auto FixSemaDC = [=](NamedDecl *D) {
3155  if (!D)
3156  return;
3157  D->setDeclContext(SemaDC);
3158  D->setLexicalDeclContext(LexDC);
3159  };
3160 
3161  FixSemaDC(NewD);
3162  if (auto *FD = dyn_cast<FunctionDecl>(NewD))
3163  FixSemaDC(FD->getDescribedFunctionTemplate());
3164  else if (auto *VD = dyn_cast<VarDecl>(NewD))
3165  FixSemaDC(VD->getDescribedVarTemplate());
3166 }
3167 
3168 /// MergeFunctionDecl - We just parsed a function 'New' from
3169 /// declarator D which has the same name and scope as a previous
3170 /// declaration 'Old'. Figure out how to resolve this situation,
3171 /// merging decls or emitting diagnostics as appropriate.
3172 ///
3173 /// In C++, New and Old must be declarations that are not
3174 /// overloaded. Use IsOverload to determine whether New and Old are
3175 /// overloaded, and to select the Old declaration that New should be
3176 /// merged with.
3177 ///
3178 /// Returns true if there was an error, false otherwise.
3180  Scope *S, bool MergeTypeWithOld) {
3181  // Verify the old decl was also a function.
3182  FunctionDecl *Old = OldD->getAsFunction();
3183  if (!Old) {
3184  if (UsingShadowDecl *Shadow = dyn_cast<UsingShadowDecl>(OldD)) {
3185  if (New->getFriendObjectKind()) {
3186  Diag(New->getLocation(), diag::err_using_decl_friend);
3187  Diag(Shadow->getTargetDecl()->getLocation(),
3188  diag::note_using_decl_target);
3189  Diag(Shadow->getUsingDecl()->getLocation(),
3190  diag::note_using_decl) << 0;
3191  return true;
3192  }
3193 
3194  // Check whether the two declarations might declare the same function.
3195  if (checkUsingShadowRedecl<FunctionDecl>(*this, Shadow, New))
3196  return true;
3197  OldD = Old = cast<FunctionDecl>(Shadow->getTargetDecl());
3198  } else {
3199  Diag(New->getLocation(), diag::err_redefinition_different_kind)
3200  << New->getDeclName();
3201  notePreviousDefinition(OldD, New->getLocation());
3202  return true;
3203  }
3204  }
3205 
3206  // If the old declaration is invalid, just give up here.
3207  if (Old->isInvalidDecl())
3208  return true;
3209 
3210  // Disallow redeclaration of some builtins.
3211  if (!getASTContext().canBuiltinBeRedeclared(Old)) {
3212  Diag(New->getLocation(), diag::err_builtin_redeclare) << Old->getDeclName();
3213  Diag(Old->getLocation(), diag::note_previous_builtin_declaration)
3214  << Old << Old->getType();
3215  return true;
3216  }
3217 
3218  diag::kind PrevDiag;
3219  SourceLocation OldLocation;
3220  std::tie(PrevDiag, OldLocation) =
3222 
3223  // Don't complain about this if we're in GNU89 mode and the old function
3224  // is an extern inline function.
3225  // Don't complain about specializations. They are not supposed to have
3226  // storage classes.
3227  if (!isa<CXXMethodDecl>(New) && !isa<CXXMethodDecl>(Old) &&
3228  New->getStorageClass() == SC_Static &&
3229  Old->hasExternalFormalLinkage() &&
3231  !canRedefineFunction(Old, getLangOpts())) {
3232  if (getLangOpts().MicrosoftExt) {
3233  Diag(New->getLocation(), diag::ext_static_non_static) << New;
3234  Diag(OldLocation, PrevDiag);
3235  } else {
3236  Diag(New->getLocation(), diag::err_static_non_static) << New;
3237  Diag(OldLocation, PrevDiag);
3238  return true;
3239  }
3240  }
3241 
3242  if (New->hasAttr<InternalLinkageAttr>() &&
3243  !Old->hasAttr<InternalLinkageAttr>()) {
3244  Diag(New->getLocation(), diag::err_internal_linkage_redeclaration)
3245  << New->getDeclName();
3246  notePreviousDefinition(Old, New->getLocation());
3247  New->dropAttr<InternalLinkageAttr>();
3248  }
3249 
3250  if (CheckRedeclarationModuleOwnership(New, Old))
3251  return true;
3252 
3253  if (!getLangOpts().CPlusPlus) {
3254  bool OldOvl = Old->hasAttr<OverloadableAttr>();
3255  if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) {
3256  Diag(New->getLocation(), diag::err_attribute_overloadable_mismatch)
3257  << New << OldOvl;
3258 
3259  // Try our best to find a decl that actually has the overloadable
3260  // attribute for the note. In most cases (e.g. programs with only one
3261  // broken declaration/definition), this won't matter.
3262  //
3263  // FIXME: We could do this if we juggled some extra state in
3264  // OverloadableAttr, rather than just removing it.
3265  const Decl *DiagOld = Old;
3266  if (OldOvl) {
3267  auto OldIter = llvm::find_if(Old->redecls(), [](const Decl *D) {
3268  const auto *A = D->getAttr<OverloadableAttr>();
3269  return A && !A->isImplicit();
3270  });
3271  // If we've implicitly added *all* of the overloadable attrs to this
3272  // chain, emitting a "previous redecl" note is pointless.
3273  DiagOld = OldIter == Old->redecls_end() ? nullptr : *OldIter;
3274  }
3275 
3276  if (DiagOld)
3277  Diag(DiagOld->getLocation(),
3278  diag::note_attribute_overloadable_prev_overload)
3279  << OldOvl;
3280 
3281  if (OldOvl)
3282  New->addAttr(OverloadableAttr::CreateImplicit(Context));
3283  else
3284  New->dropAttr<OverloadableAttr>();
3285  }
3286  }
3287 
3288  // If a function is first declared with a calling convention, but is later
3289  // declared or defined without one, all following decls assume the calling
3290  // convention of the first.
3291  //
3292  // It's OK if a function is first declared without a calling convention,
3293  // but is later declared or defined with the default calling convention.
3294  //
3295  // To test if either decl has an explicit calling convention, we look for
3296  // AttributedType sugar nodes on the type as written. If they are missing or
3297  // were canonicalized away, we assume the calling convention was implicit.
3298  //
3299  // Note also that we DO NOT return at this point, because we still have
3300  // other tests to run.
3301  QualType OldQType = Context.getCanonicalType(Old->getType());
3302  QualType NewQType = Context.getCanonicalType(New->getType());
3303  const FunctionType *OldType = cast<FunctionType>(OldQType);
3304  const FunctionType *NewType = cast<FunctionType>(NewQType);
3305  FunctionType::ExtInfo OldTypeInfo = OldType->getExtInfo();
3306  FunctionType::ExtInfo NewTypeInfo = NewType->getExtInfo();
3307  bool RequiresAdjustment = false;
3308 
3309  if (OldTypeInfo.getCC() != NewTypeInfo.getCC()) {
3310  FunctionDecl *First = Old->getFirstDecl();
3311  const FunctionType *FT =
3313  FunctionType::ExtInfo FI = FT->getExtInfo();
3314  bool NewCCExplicit = getCallingConvAttributedType(New->getType());
3315  if (!NewCCExplicit) {
3316  // Inherit the CC from the previous declaration if it was specified
3317  // there but not here.
3318  NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
3319  RequiresAdjustment = true;
3320  } else if (New->getBuiltinID()) {
3321  // Calling Conventions on a Builtin aren't really useful and setting a
3322  // default calling convention and cdecl'ing some builtin redeclarations is
3323  // common, so warn and ignore the calling convention on the redeclaration.
3324  Diag(New->getLocation(), diag::warn_cconv_unsupported)
3325  << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
3326  << (int)CallingConventionIgnoredReason::BuiltinFunction;
3327  NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
3328  RequiresAdjustment = true;
3329  } else {
3330  // Calling conventions aren't compatible, so complain.
3331  bool FirstCCExplicit = getCallingConvAttributedType(First->getType());
3332  Diag(New->getLocation(), diag::err_cconv_change)
3333  << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
3334  << !FirstCCExplicit
3335  << (!FirstCCExplicit ? "" :
3336  FunctionType::getNameForCallConv(FI.getCC()));
3337 
3338  // Put the note on the first decl, since it is the one that matters.
3339  Diag(First->getLocation(), diag::note_previous_declaration);
3340  return true;
3341  }
3342  }
3343 
3344  // FIXME: diagnose the other way around?
3345  if (OldTypeInfo.getNoReturn() && !NewTypeInfo.getNoReturn()) {
3346  NewTypeInfo = NewTypeInfo.withNoReturn(true);
3347  RequiresAdjustment = true;
3348  }
3349 
3350  // Merge regparm attribute.
3351  if (OldTypeInfo.getHasRegParm() != NewTypeInfo.getHasRegParm() ||
3352  OldTypeInfo.getRegParm() != NewTypeInfo.getRegParm()) {
3353  if (NewTypeInfo.getHasRegParm()) {
3354  Diag(New->getLocation(), diag::err_regparm_mismatch)
3355  << NewType->getRegParmType()
3356  << OldType->getRegParmType();
3357  Diag(OldLocation, diag::note_previous_declaration);
3358  return true;
3359  }
3360 
3361  NewTypeInfo = NewTypeInfo.withRegParm(OldTypeInfo.getRegParm());
3362  RequiresAdjustment = true;
3363  }
3364 
3365  // Merge ns_returns_retained attribute.
3366  if (OldTypeInfo.getProducesResult() != NewTypeInfo.getProducesResult()) {
3367  if (NewTypeInfo.getProducesResult()) {
3368  Diag(New->getLocation(), diag::err_function_attribute_mismatch)
3369  << "'ns_returns_retained'";
3370  Diag(OldLocation, diag::note_previous_declaration);
3371  return true;
3372  }
3373 
3374  NewTypeInfo = NewTypeInfo.withProducesResult(true);
3375  RequiresAdjustment = true;
3376  }
3377 
3378  if (OldTypeInfo.getNoCallerSavedRegs() !=
3379  NewTypeInfo.getNoCallerSavedRegs()) {
3380  if (NewTypeInfo.getNoCallerSavedRegs()) {
3381  AnyX86NoCallerSavedRegistersAttr *Attr =
3382  New->getAttr<AnyX86NoCallerSavedRegistersAttr>();
3383  Diag(New->getLocation(), diag::err_function_attribute_mismatch) << Attr;
3384  Diag(OldLocation, diag::note_previous_declaration);
3385  return true;
3386  }
3387 
3388  NewTypeInfo = NewTypeInfo.withNoCallerSavedRegs(true);
3389  RequiresAdjustment = true;
3390  }
3391 
3392  if (RequiresAdjustment) {
3393  const FunctionType *AdjustedType = New->getType()->getAs<FunctionType>();
3394  AdjustedType = Context.adjustFunctionType(AdjustedType, NewTypeInfo);
3395  New->setType(QualType(AdjustedType, 0));
3396  NewQType = Context.getCanonicalType(New->getType());
3397  }
3398 
3399  // If this redeclaration makes the function inline, we may need to add it to
3400  // UndefinedButUsed.
3401  if (!Old->isInlined() && New->isInlined() &&
3402  !New->hasAttr<GNUInlineAttr>() &&
3403  !getLangOpts().GNUInline &&
3404  Old->isUsed(false) &&
3405  !Old->isDefined() && !New->isThisDeclarationADefinition())
3406  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
3407  SourceLocation()));
3408 
3409  // If this redeclaration makes it newly gnu_inline, we don't want to warn
3410  // about it.
3411  if (New->hasAttr<GNUInlineAttr>() &&
3412  Old->isInlined() && !Old->hasAttr<GNUInlineAttr>()) {
3413  UndefinedButUsed.erase(Old->getCanonicalDecl());
3414  }
3415 
3416  // If pass_object_size params don't match up perfectly, this isn't a valid
3417  // redeclaration.
3418  if (Old->getNumParams() > 0 && Old->getNumParams() == New->getNumParams() &&
3419  !hasIdenticalPassObjectSizeAttrs(Old, New)) {
3420  Diag(New->getLocation(), diag::err_different_pass_object_size_params)
3421  << New->getDeclName();
3422  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3423  return true;
3424  }
3425 
3426  if (getLangOpts().CPlusPlus) {
3427  // C++1z [over.load]p2
3428  // Certain function declarations cannot be overloaded:
3429  // -- Function declarations that differ only in the return type,
3430  // the exception specification, or both cannot be overloaded.
3431 
3432  // Check the exception specifications match. This may recompute the type of
3433  // both Old and New if it resolved exception specifications, so grab the
3434  // types again after this. Because this updates the type, we do this before
3435  // any of the other checks below, which may update the "de facto" NewQType
3436  // but do not necessarily update the type of New.
3437  if (CheckEquivalentExceptionSpec(Old, New))
3438  return true;
3439  OldQType = Context.getCanonicalType(Old->getType());
3440  NewQType = Context.getCanonicalType(New->getType());
3441 
3442  // Go back to the type source info to compare the declared return types,
3443  // per C++1y [dcl.type.auto]p13:
3444  // Redeclarations or specializations of a function or function template
3445  // with a declared return type that uses a placeholder type shall also
3446  // use that placeholder, not a deduced type.
3447  QualType OldDeclaredReturnType = Old->getDeclaredReturnType();
3448  QualType NewDeclaredReturnType = New->getDeclaredReturnType();
3449  if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
3450  canFullyTypeCheckRedeclaration(New, Old, NewDeclaredReturnType,
3451  OldDeclaredReturnType)) {
3452  QualType ResQT;
3453  if (NewDeclaredReturnType->isObjCObjectPointerType() &&
3454  OldDeclaredReturnType->isObjCObjectPointerType())
3455  // FIXME: This does the wrong thing for a deduced return type.
3456  ResQT = Context.mergeObjCGCQualifiers(NewQType, OldQType);
3457  if (ResQT.isNull()) {
3458  if (New->isCXXClassMember() && New->isOutOfLine())
3459  Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type)
3460  << New << New->getReturnTypeSourceRange();
3461  else
3462  Diag(New->getLocation(), diag::err_ovl_diff_return_type)
3463  << New->getReturnTypeSourceRange();
3464  Diag(OldLocation, PrevDiag) << Old << Old->getType()
3465  << Old->getReturnTypeSourceRange();
3466  return true;
3467  }
3468  else
3469  NewQType = ResQT;
3470  }
3471 
3472  QualType OldReturnType = OldType->getReturnType();
3473  QualType NewReturnType = cast<FunctionType>(NewQType)->getReturnType();
3474  if (OldReturnType != NewReturnType) {
3475  // If this function has a deduced return type and has already been
3476  // defined, copy the deduced value from the old declaration.
3477  AutoType *OldAT = Old->getReturnType()->getContainedAutoType();
3478  if (OldAT && OldAT->isDeduced()) {
3479  New->setType(
3480  SubstAutoType(New->getType(),
3481  OldAT->isDependentType() ? Context.DependentTy
3482  : OldAT->getDeducedType()));
3483  NewQType = Context.getCanonicalType(
3484  SubstAutoType(NewQType,
3485  OldAT->isDependentType() ? Context.DependentTy
3486  : OldAT->getDeducedType()));
3487  }
3488  }
3489 
3490  const CXXMethodDecl *OldMethod = dyn_cast<CXXMethodDecl>(Old);
3491  CXXMethodDecl *NewMethod = dyn_cast<CXXMethodDecl>(New);
3492  if (OldMethod && NewMethod) {
3493  // Preserve triviality.
3494  NewMethod->setTrivial(OldMethod->isTrivial());
3495 
3496  // MSVC allows explicit template specialization at class scope:
3497  // 2 CXXMethodDecls referring to the same function will be injected.
3498  // We don't want a redeclaration error.
3499  bool IsClassScopeExplicitSpecialization =
3500  OldMethod->isFunctionTemplateSpecialization() &&
3501  NewMethod->isFunctionTemplateSpecialization();
3502  bool isFriend = NewMethod->getFriendObjectKind();
3503 
3504  if (!isFriend && NewMethod->getLexicalDeclContext()->isRecord() &&
3505  !IsClassScopeExplicitSpecialization) {
3506  // -- Member function declarations with the same name and the
3507  // same parameter types cannot be overloaded if any of them
3508  // is a static member function declaration.
3509  if (OldMethod->isStatic() != NewMethod->isStatic()) {
3510  Diag(New->getLocation(), diag::err_ovl_static_nonstatic_member);
3511  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3512  return true;
3513  }
3514 
3515  // C++ [class.mem]p1:
3516  // [...] A member shall not be declared twice in the
3517  // member-specification, except that a nested class or member
3518  // class template can be declared and then later defined.
3519  if (!inTemplateInstantiation()) {
3520  unsigned NewDiag;
3521  if (isa<CXXConstructorDecl>(OldMethod))
3522  NewDiag = diag::err_constructor_redeclared;
3523  else if (isa<CXXDestructorDecl>(NewMethod))
3524  NewDiag = diag::err_destructor_redeclared;
3525  else if (isa<CXXConversionDecl>(NewMethod))
3526  NewDiag = diag::err_conv_function_redeclared;
3527  else
3528  NewDiag = diag::err_member_redeclared;
3529 
3530  Diag(New->getLocation(), NewDiag);
3531  } else {
3532  Diag(New->getLocation(), diag::err_member_redeclared_in_instantiation)
3533  << New << New->getType();
3534  }
3535  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3536  return true;
3537 
3538  // Complain if this is an explicit declaration of a special
3539  // member that was initially declared implicitly.
3540  //
3541  // As an exception, it's okay to befriend such methods in order
3542  // to permit the implicit constructor/destructor/operator calls.
3543  } else if (OldMethod->isImplicit()) {
3544  if (isFriend) {
3545  NewMethod->setImplicit();
3546  } else {
3547  Diag(NewMethod->getLocation(),
3548  diag::err_definition_of_implicitly_declared_member)
3549  << New << getSpecialMember(OldMethod);
3550  return true;
3551  }
3552  } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
3553  Diag(NewMethod->getLocation(),
3554  diag::err_definition_of_explicitly_defaulted_member)
3555  << getSpecialMember(OldMethod);
3556  return true;
3557  }
3558  }
3559 
3560  // C++11 [dcl.attr.noreturn]p1:
3561  // The first declaration of a function shall specify the noreturn
3562  // attribute if any declaration of that function specifies the noreturn
3563  // attribute.
3564  const CXX11NoReturnAttr *NRA = New->getAttr<CXX11NoReturnAttr>();
3565  if (NRA && !Old->hasAttr<CXX11NoReturnAttr>()) {
3566  Diag(NRA->getLocation(), diag::err_noreturn_missing_on_first_decl);
3567  Diag(Old->getFirstDecl()->getLocation(),
3568  diag::note_noreturn_missing_first_decl);
3569  }
3570 
3571  // C++11 [dcl.attr.depend]p2:
3572  // The first declaration of a function shall specify the
3573  // carries_dependency attribute for its declarator-id if any declaration
3574  // of the function specifies the carries_dependency attribute.
3575  const CarriesDependencyAttr *CDA = New->getAttr<CarriesDependencyAttr>();
3576  if (CDA && !Old->hasAttr<CarriesDependencyAttr>()) {
3577  Diag(CDA->getLocation(),
3578  diag::err_carries_dependency_missing_on_first_decl) << 0/*Function*/;
3579  Diag(Old->getFirstDecl()->getLocation(),
3580  diag::note_carries_dependency_missing_first_decl) << 0/*Function*/;
3581  }
3582 
3583  // (C++98 8.3.5p3):
3584  // All declarations for a function shall agree exactly in both the
3585  // return type and the parameter-type-list.
3586  // We also want to respect all the extended bits except noreturn.
3587 
3588  // noreturn should now match unless the old type info didn't have it.
3589  QualType OldQTypeForComparison = OldQType;
3590  if (!OldTypeInfo.getNoReturn() && NewTypeInfo.getNoReturn()) {
3591  auto *OldType = OldQType->castAs<FunctionProtoType>();
3592  const FunctionType *OldTypeForComparison
3593  = Context.adjustFunctionType(OldType, OldTypeInfo.withNoReturn(true));
3594  OldQTypeForComparison = QualType(OldTypeForComparison, 0);
3595  assert(OldQTypeForComparison.isCanonical());
3596  }
3597 
3598  if (haveIncompatibleLanguageLinkages(Old, New)) {
3599  // As a special case, retain the language linkage from previous
3600  // declarations of a friend function as an extension.
3601  //
3602  // This liberal interpretation of C++ [class.friend]p3 matches GCC/MSVC
3603  // and is useful because there's otherwise no way to specify language
3604  // linkage within class scope.
3605  //
3606  // Check cautiously as the friend object kind isn't yet complete.
3607  if (New->getFriendObjectKind() != Decl::FOK_None) {
3608  Diag(New->getLocation(), diag::ext_retained_language_linkage) << New;
3609  Diag(OldLocation, PrevDiag);
3610  } else {
3611  Diag(New->getLocation(), diag::err_different_language_linkage) << New;
3612  Diag(OldLocation, PrevDiag);
3613  return true;
3614  }
3615  }
3616 
3617  // If the function types are compatible, merge the declarations. Ignore the
3618  // exception specifier because it was already checked above in
3619  // CheckEquivalentExceptionSpec, and we don't want follow-on diagnostics
3620  // about incompatible types under -fms-compatibility.
3621  if (Context.hasSameFunctionTypeIgnoringExceptionSpec(OldQTypeForComparison,
3622  NewQType))
3623  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3624 
3625  // If the types are imprecise (due to dependent constructs in friends or
3626  // local extern declarations), it's OK if they differ. We'll check again
3627  // during instantiation.
3628  if (!canFullyTypeCheckRedeclaration(New, Old, NewQType, OldQType))
3629  return false;
3630 
3631  // Fall through for conflicting redeclarations and redefinitions.
3632  }
3633 
3634  // C: Function types need to be compatible, not identical. This handles
3635  // duplicate function decls like "void f(int); void f(enum X);" properly.
3636  if (!getLangOpts().CPlusPlus &&
3637  Context.typesAreCompatible(OldQType, NewQType)) {
3638  const FunctionType *OldFuncType = OldQType->getAs<FunctionType>();
3639  const FunctionType *NewFuncType = NewQType->getAs<FunctionType>();
3640  const FunctionProtoType *OldProto = nullptr;
3641  if (MergeTypeWithOld && isa<FunctionNoProtoType>(NewFuncType) &&
3642  (OldProto = dyn_cast<FunctionProtoType>(OldFuncType))) {
3643  // The old declaration provided a function prototype, but the
3644  // new declaration does not. Merge in the prototype.
3645  assert(!OldProto->hasExceptionSpec() && "Exception spec in C");
3646  SmallVector<QualType, 16> ParamTypes(OldProto->param_types());
3647  NewQType =
3648  Context.getFunctionType(NewFuncType->getReturnType(), ParamTypes,
3649  OldProto->getExtProtoInfo());
3650  New->setType(NewQType);
3651  New->setHasInheritedPrototype();
3652 
3653  // Synthesize parameters with the same types.
3655  for (const auto &ParamType : OldProto->param_types()) {
3656  ParmVarDecl *Param = ParmVarDecl::Create(Context, New, SourceLocation(),
3657  SourceLocation(), nullptr,
3658  ParamType, /*TInfo=*/nullptr,
3659  SC_None, nullptr);
3660  Param->setScopeInfo(0, Params.size());
3661  Param->setImplicit();
3662  Params.push_back(Param);
3663  }
3664 
3665  New->setParams(Params);
3666  }
3667 
3668  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3669  }
3670 
3671  // GNU C permits a K&R definition to follow a prototype declaration
3672  // if the declared types of the parameters in the K&R definition
3673  // match the types in the prototype declaration, even when the
3674  // promoted types of the parameters from the K&R definition differ
3675  // from the types in the prototype. GCC then keeps the types from
3676  // the prototype.
3677  //
3678  // If a variadic prototype is followed by a non-variadic K&R definition,
3679  // the K&R definition becomes variadic. This is sort of an edge case, but
3680  // it's legal per the standard depending on how you read C99 6.7.5.3p15 and
3681  // C99 6.9.1p8.
3682  if (!getLangOpts().CPlusPlus &&
3683  Old->hasPrototype() && !New->hasPrototype() &&
3684  New->getType()->getAs<FunctionProtoType>() &&
3685  Old->getNumParams() == New->getNumParams()) {
3686  SmallVector<QualType, 16> ArgTypes;
3688  const FunctionProtoType *OldProto
3689  = Old->getType()->getAs<FunctionProtoType>();
3690  const FunctionProtoType *NewProto
3691  = New->getType()->getAs<FunctionProtoType>();
3692 
3693  // Determine whether this is the GNU C extension.
3694  QualType MergedReturn = Context.mergeTypes(OldProto->getReturnType(),
3695  NewProto->getReturnType());
3696  bool LooseCompatible = !MergedReturn.isNull();
3697  for (unsigned Idx = 0, End = Old->getNumParams();
3698  LooseCompatible && Idx != End; ++Idx) {
3699  ParmVarDecl *OldParm = Old->getParamDecl(Idx);
3700  ParmVarDecl *NewParm = New->getParamDecl(Idx);
3701  if (Context.typesAreCompatible(OldParm->getType(),
3702  NewProto->getParamType(Idx))) {
3703  ArgTypes.push_back(NewParm->getType());
3704  } else if (Context.typesAreCompatible(OldParm->getType(),
3705  NewParm->getType(),
3706  /*CompareUnqualified=*/true)) {
3707  GNUCompatibleParamWarning Warn = { OldParm, NewParm,
3708  NewProto->getParamType(Idx) };
3709  Warnings.push_back(Warn);
3710  ArgTypes.push_back(NewParm->getType());
3711  } else
3712  LooseCompatible = false;
3713  }
3714 
3715  if (LooseCompatible) {
3716  for (unsigned Warn = 0; Warn < Warnings.size(); ++Warn) {
3717  Diag(Warnings[Warn].NewParm->getLocation(),
3718  diag::ext_param_promoted_not_compatible_with_prototype)
3719  << Warnings[Warn].PromotedType
3720  << Warnings[Warn].OldParm->getType();
3721  if (Warnings[Warn].OldParm->getLocation().isValid())
3722  Diag(Warnings[Warn].OldParm->getLocation(),
3723  diag::note_previous_declaration);
3724  }
3725 
3726  if (MergeTypeWithOld)
3727  New->setType(Context.getFunctionType(MergedReturn, ArgTypes,
3728  OldProto->getExtProtoInfo()));
3729  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3730  }
3731 
3732  // Fall through to diagnose conflicting types.
3733  }
3734 
3735  // A function that has already been declared has been redeclared or
3736  // defined with a different type; show an appropriate diagnostic.
3737 
3738  // If the previous declaration was an implicitly-generated builtin
3739  // declaration, then at the very least we should use a specialized note.
3740  unsigned BuiltinID;
3741  if (Old->isImplicit() && (BuiltinID = Old->getBuiltinID())) {
3742  // If it's actually a library-defined builtin function like 'malloc'
3743  // or 'printf', just warn about the incompatible redeclaration.
3744  if (Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) {
3745  Diag(New->getLocation(), diag::warn_redecl_library_builtin) << New;
3746  Diag(OldLocation, diag::note_previous_builtin_declaration)
3747  << Old << Old->getType();
3748 
3749  // If this is a global redeclaration, just forget hereafter
3750  // about the "builtin-ness" of the function.
3751  //
3752  // Doing this for local extern declarations is problematic. If
3753  // the builtin declaration remains visible, a second invalid
3754  // local declaration will produce a hard error; if it doesn't
3755  // remain visible, a single bogus local redeclaration (which is
3756  // actually only a warning) could break all the downstream code.
3758  New->getIdentifier()->revertBuiltin();
3759 
3760  return false;
3761  }
3762 
3763  PrevDiag = diag::note_previous_builtin_declaration;
3764  }
3765 
3766  Diag(New->getLocation(), diag::err_conflicting_types) << New->getDeclName();
3767  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3768  return true;
3769 }
3770 
3771 /// Completes the merge of two function declarations that are
3772 /// known to be compatible.
3773 ///
3774 /// This routine handles the merging of attributes and other
3775 /// properties of function declarations from the old declaration to
3776 /// the new declaration, once we know that New is in fact a
3777 /// redeclaration of Old.
3778 ///
3779 /// \returns false
3781  Scope *S, bool MergeTypeWithOld) {
3782  // Merge the attributes
3783  mergeDeclAttributes(New, Old);
3784 
3785  // Merge "pure" flag.
3786  if (Old->isPure())
3787  New->setPure();
3788 
3789  // Merge "used" flag.
3790  if (Old->getMostRecentDecl()->isUsed(false))
3791  New->setIsUsed();
3792 
3793  // Merge attributes from the parameters. These can mismatch with K&R
3794  // declarations.
3795  if (New->getNumParams() == Old->getNumParams())
3796  for (unsigned i = 0, e = New->getNumParams(); i != e; ++i) {
3797  ParmVarDecl *NewParam = New->getParamDecl(i);
3798  ParmVarDecl *OldParam = Old->getParamDecl(i);
3799  mergeParamDeclAttributes(NewParam, OldParam, *this);
3800  mergeParamDeclTypes(NewParam, OldParam, *this);
3801  }
3802 
3803  if (getLangOpts().CPlusPlus)
3804  return MergeCXXFunctionDecl(New, Old, S);
3805 
3806  // Merge the function types so the we get the composite types for the return
3807  // and argument types. Per C11 6.2.7/4, only update the type if the old decl
3808  // was visible.
3809  QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
3810  if (!Merged.isNull() && MergeTypeWithOld)
3811  New->setType(Merged);
3812 
3813  return false;
3814 }
3815 
3817  ObjCMethodDecl *oldMethod) {
3818  // Merge the attributes, including deprecated/unavailable
3819  AvailabilityMergeKind MergeKind =
3820  isa<ObjCProtocolDecl>(oldMethod->getDeclContext())
3821  ? AMK_ProtocolImplementation
3822  : isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
3823  : AMK_Override;
3824 
3825  mergeDeclAttributes(newMethod, oldMethod, MergeKind);
3826 
3827  // Merge attributes from the parameters.
3829  oe = oldMethod->param_end();
3831  ni = newMethod->param_begin(), ne = newMethod->param_end();
3832  ni != ne && oi != oe; ++ni, ++oi)
3833  mergeParamDeclAttributes(*ni, *oi, *this);
3834 
3835  CheckObjCMethodOverride(newMethod, oldMethod);
3836 }
3837 
3838 static void diagnoseVarDeclTypeMismatch(Sema &S, VarDecl *New, VarDecl* Old) {
3839  assert(!S.Context.hasSameType(New->getType(), Old->getType()));
3840 
3842  ? diag::err_redefinition_different_type
3843  : diag::err_redeclaration_different_type)
3844  << New->getDeclName() << New->getType() << Old->getType();
3845 
3846  diag::kind PrevDiag;
3847  SourceLocation OldLocation;
3848  std::tie(PrevDiag, OldLocation)
3850  S.Diag(OldLocation, PrevDiag);
3851  New->setInvalidDecl();
3852 }
3853 
3854 /// MergeVarDeclTypes - We parsed a variable 'New' which has the same name and
3855 /// scope as a previous declaration 'Old'. Figure out how to merge their types,
3856 /// emitting diagnostics as appropriate.
3857 ///
3858 /// Declarations using the auto type specifier (C++ [decl.spec.auto]) call back
3859 /// to here in AddInitializerToDecl. We can't check them before the initializer
3860 /// is attached.
3862  bool MergeTypeWithOld) {
3863  if (New->isInvalidDecl() || Old->isInvalidDecl())
3864  return;
3865 
3866  QualType MergedT;
3867  if (getLangOpts().CPlusPlus) {
3868  if (New->getType()->isUndeducedType()) {
3869  // We don't know what the new type is until the initializer is attached.
3870  return;
3871  } else if (Context.hasSameType(New->getType(), Old->getType())) {
3872  // These could still be something that needs exception specs checked.
3873  return MergeVarDeclExceptionSpecs(New, Old);
3874  }
3875  // C++ [basic.link]p10:
3876  // [...] the types specified by all declarations referring to a given
3877  // object or function shall be identical, except that declarations for an
3878  // array object can specify array types that differ by the presence or
3879  // absence of a major array bound (8.3.4).
3880  else if (Old->getType()->isArrayType() && New->getType()->isArrayType()) {
3881  const ArrayType *OldArray = Context.getAsArrayType(Old->getType());
3882  const ArrayType *NewArray = Context.getAsArrayType(New->getType());
3883 
3884  // We are merging a variable declaration New into Old. If it has an array
3885  // bound, and that bound differs from Old's bound, we should diagnose the
3886  // mismatch.
3887  if (!NewArray->isIncompleteArrayType() && !NewArray->isDependentType()) {
3888  for (VarDecl *PrevVD = Old->getMostRecentDecl(); PrevVD;
3889  PrevVD = PrevVD->getPreviousDecl()) {
3890  const ArrayType *PrevVDTy = Context.getAsArrayType(PrevVD->getType());
3891  if (PrevVDTy->isIncompleteArrayType() || PrevVDTy->isDependentType())
3892  continue;
3893 
3894  if (!Context.hasSameType(NewArray, PrevVDTy))
3895  return diagnoseVarDeclTypeMismatch(*this, New, PrevVD);
3896  }
3897  }
3898 
3899  if (OldArray->isIncompleteArrayType() && NewArray->isArrayType()) {
3900  if (Context.hasSameType(OldArray->getElementType(),
3901  NewArray->getElementType()))
3902  MergedT = New->getType();
3903  }
3904  // FIXME: Check visibility. New is hidden but has a complete type. If New
3905  // has no array bound, it should not inherit one from Old, if Old is not
3906  // visible.
3907  else if (OldArray->isArrayType() && NewArray->isIncompleteArrayType()) {
3908  if (Context.hasSameType(OldArray->getElementType(),
3909  NewArray->getElementType()))
3910  MergedT = Old->getType();
3911  }
3912  }
3913  else if (New->getType()->isObjCObjectPointerType() &&
3914  Old->getType()->isObjCObjectPointerType()) {
3915  MergedT = Context.mergeObjCGCQualifiers(New->getType(),
3916  Old->getType());
3917  }
3918  } else {
3919  // C 6.2.7p2:
3920  // All declarations that refer to the same object or function shall have
3921  // compatible type.
3922  MergedT = Context.mergeTypes(New->getType(), Old->getType());
3923  }
3924  if (MergedT.isNull()) {
3925  // It's OK if we couldn't merge types if either type is dependent, for a
3926  // block-scope variable. In other cases (static data members of class
3927  // templates, variable templates, ...), we require the types to be
3928  // equivalent.
3929  // FIXME: The C++ standard doesn't say anything about this.
3930  if ((New->getType()->isDependentType() ||
3931  Old->getType()->isDependentType()) && New->isLocalVarDecl()) {
3932  // If the old type was dependent, we can't merge with it, so the new type
3933  // becomes dependent for now. We'll reproduce the original type when we
3934  // instantiate the TypeSourceInfo for the variable.
3935  if (!New->getType()->isDependentType() && MergeTypeWithOld)
3936  New->setType(Context.DependentTy);
3937  return;
3938  }
3939  return diagnoseVarDeclTypeMismatch(*this, New, Old);
3940  }
3941 
3942  // Don't actually update the type on the new declaration if the old
3943  // declaration was an extern declaration in a different scope.
3944  if (MergeTypeWithOld)
3945  New->setType(MergedT);
3946 }
3947 
3948 static bool mergeTypeWithPrevious(Sema &S, VarDecl *NewVD, VarDecl *OldVD,
3950  // C11 6.2.7p4:
3951  // For an identifier with internal or external linkage declared
3952  // in a scope in which a prior declaration of that identifier is
3953  // visible, if the prior declaration specifies internal or
3954  // external linkage, the type of the identifier at the later
3955  // declaration becomes the composite type.
3956  //
3957  // If the variable isn't visible, we do not merge with its type.
3958  if (Previous.isShadowed())
3959  return false;
3960 
3961  if (S.getLangOpts().CPlusPlus) {
3962  // C++11 [dcl.array]p3:
3963  // If there is a preceding declaration of the entity in the same
3964  // scope in which the bound was specified, an omitted array bound
3965  // is taken to be the same as in that earlier declaration.
3966  return NewVD->isPreviousDeclInSameBlockScope() ||
3967  (!OldVD->getLexicalDeclContext()->isFunctionOrMethod() &&
3969  } else {
3970  // If the old declaration was function-local, don't merge with its
3971  // type unless we're in the same function.
3972  return !OldVD->getLexicalDeclContext()->isFunctionOrMethod() ||
3973  OldVD->getLexicalDeclContext() == NewVD->getLexicalDeclContext();
3974  }
3975 }
3976 
3977 /// MergeVarDecl - We just parsed a variable 'New' which has the same name
3978 /// and scope as a previous declaration 'Old'. Figure out how to resolve this
3979 /// situation, merging decls or emitting diagnostics as appropriate.
3980 ///
3981 /// Tentative definition rules (C99 6.9.2p2) are checked by
3982 /// FinalizeDeclaratorGroup. Unfortunately, we can't analyze tentative
3983 /// definitions here, since the initializer hasn't been attached.
3984 ///
3986  // If the new decl is already invalid, don't do any other checking.
3987  if (New->isInvalidDecl())
3988  return;
3989 
3990  if (!shouldLinkPossiblyHiddenDecl(Previous, New))
3991  return;
3992 
3993  VarTemplateDecl *NewTemplate = New->getDescribedVarTemplate();
3994 
3995  // Verify the old decl was also a variable or variable template.
3996  VarDecl *Old = nullptr;
3997  VarTemplateDecl *OldTemplate = nullptr;
3998  if (Previous.isSingleResult()) {
3999  if (NewTemplate) {
4000  OldTemplate = dyn_cast<VarTemplateDecl>(Previous.getFoundDecl());
4001  Old = OldTemplate ? OldTemplate->getTemplatedDecl() : nullptr;
4002 
4003  if (auto *Shadow =
4004  dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
4005  if (checkUsingShadowRedecl<VarTemplateDecl>(*this, Shadow, NewTemplate))
4006  return New->setInvalidDecl();
4007  } else {
4008  Old = dyn_cast<VarDecl>(Previous.getFoundDecl());
4009 
4010  if (auto *Shadow =
4011  dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
4012  if (checkUsingShadowRedecl<VarDecl>(*this, Shadow, New))
4013  return New->setInvalidDecl();
4014  }
4015  }
4016  if (!Old) {
4017  Diag(New->getLocation(), diag::err_redefinition_different_kind)
4018  << New->getDeclName();
4019  notePreviousDefinition(Previous.getRepresentativeDecl(),
4020  New->getLocation());
4021  return New->setInvalidDecl();
4022  }
4023 
4024  // Ensure the template parameters are compatible.
4025  if (NewTemplate &&
4026  !TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
4027  OldTemplate->getTemplateParameters(),
4028  /*Complain=*/true, TPL_TemplateMatch))
4029  return New->setInvalidDecl();
4030 
4031  // C++ [class.mem]p1:
4032  // A member shall not be declared twice in the member-specification [...]
4033  //
4034  // Here, we need only consider static data members.
4035  if (Old->isStaticDataMember() && !New->isOutOfLine()) {
4036  Diag(New->getLocation(), diag::err_duplicate_member)
4037  << New->getIdentifier();
4038  Diag(Old->getLocation(), diag::note_previous_declaration);
4039  New->setInvalidDecl();
4040  }
4041 
4042  mergeDeclAttributes(New, Old);
4043  // Warn if an already-declared variable is made a weak_import in a subsequent
4044  // declaration
4045  if (New->hasAttr<WeakImportAttr>() &&
4046  Old->getStorageClass() == SC_None &&
4047  !Old->hasAttr<WeakImportAttr>()) {
4048  Diag(New->getLocation(), diag::warn_weak_import) << New->getDeclName();
4049  notePreviousDefinition(Old, New->getLocation());
4050  // Remove weak_import attribute on new declaration.
4051  New->dropAttr<WeakImportAttr>();
4052  }
4053 
4054  if (New->hasAttr<InternalLinkageAttr>() &&
4055  !Old->hasAttr<InternalLinkageAttr>()) {
4056  Diag(New->getLocation(), diag::err_internal_linkage_redeclaration)
4057  << New->getDeclName();
4058  notePreviousDefinition(Old, New->getLocation());
4059  New->dropAttr<InternalLinkageAttr>();
4060  }
4061 
4062  // Merge the types.
4063  VarDecl *MostRecent = Old->getMostRecentDecl();
4064  if (MostRecent != Old) {
4065  MergeVarDeclTypes(New, MostRecent,
4066  mergeTypeWithPrevious(*this, New, MostRecent, Previous));
4067  if (New->isInvalidDecl())
4068  return;
4069  }
4070 
4071  MergeVarDeclTypes(New, Old, mergeTypeWithPrevious(*this, New, Old, Previous));
4072  if (New->isInvalidDecl())
4073  return;
4074 
4075  diag::kind PrevDiag;
4076  SourceLocation OldLocation;
4077  std::tie(PrevDiag, OldLocation) =
4079 
4080  // [dcl.stc]p8: Check if we have a non-static decl followed by a static.
4081  if (New->getStorageClass() == SC_Static &&
4082  !New->isStaticDataMember() &&
4083  Old->hasExternalFormalLinkage()) {
4084  if (getLangOpts().MicrosoftExt) {
4085  Diag(New->getLocation(), diag::ext_static_non_static)
4086  << New->getDeclName();
4087  Diag(OldLocation, PrevDiag);
4088  } else {
4089  Diag(New->getLocation(), diag::err_static_non_static)
4090  << New->getDeclName();
4091  Diag(OldLocation, PrevDiag);
4092  return New->setInvalidDecl();
4093  }
4094  }
4095  // C99 6.2.2p4:
4096  // For an identifier declared with the storage-class specifier
4097  // extern in a scope in which a prior declaration of that
4098  // identifier is visible,23) if the prior declaration specifies
4099  // internal or external linkage, the linkage of the identifier at
4100  // the later declaration is the same as the linkage specified at
4101  // the prior declaration. If no prior declaration is visible, or
4102  // if the prior declaration specifies no linkage, then the
4103  // identifier has external linkage.
4104  if (New->hasExternalStorage() && Old->hasLinkage())
4105  /* Okay */;
4106  else if (New->getCanonicalDecl()->getStorageClass() != SC_Static &&
4107  !New->isStaticDataMember() &&
4109  Diag(New->getLocation(), diag::err_non_static_static) << New->getDeclName();
4110  Diag(OldLocation, PrevDiag);
4111  return New->setInvalidDecl();
4112  }
4113 
4114  // Check if extern is followed by non-extern and vice-versa.
4115  if (New->hasExternalStorage() &&
4116  !Old->hasLinkage() && Old->isLocalVarDeclOrParm()) {
4117  Diag(New->getLocation(), diag::err_extern_non_extern) << New->getDeclName();
4118  Diag(OldLocation, PrevDiag);
4119  return New->setInvalidDecl();
4120  }
4121  if (Old->hasLinkage() && New->isLocalVarDeclOrParm() &&
4122  !New->hasExternalStorage()) {
4123  Diag(New->getLocation(), diag::err_non_extern_extern) << New->getDeclName();
4124  Diag(OldLocation, PrevDiag);
4125  return New->setInvalidDecl();
4126  }
4127 
4128  if (CheckRedeclarationModuleOwnership(New, Old))
4129  return;
4130 
4131  // Variables with external linkage are analyzed in FinalizeDeclaratorGroup.
4132 
4133  // FIXME: The test for external storage here seems wrong? We still
4134  // need to check for mismatches.
4135  if (!New->hasExternalStorage() && !New->isFileVarDecl() &&
4136  // Don't complain about out-of-line definitions of static members.
4137  !(Old->getLexicalDeclContext()->isRecord() &&
4138  !New->getLexicalDeclContext()->isRecord())) {
4139  Diag(New->getLocation(), diag::err_redefinition) << New->getDeclName();
4140  Diag(OldLocation, PrevDiag);
4141  return New->setInvalidDecl();
4142  }
4143 
4144  if (New->isInline() && !Old->getMostRecentDecl()->isInline()) {
4145  if (VarDecl *Def = Old->getDefinition()) {
4146  // C++1z [dcl.fcn.spec]p4:
4147  // If the definition of a variable appears in a translation unit before
4148  // its first declaration as inline, the program is ill-formed.
4149  Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
4150  Diag(Def->getLocation(), diag::note_previous_definition);
4151  }
4152  }
4153 
4154  // If this redeclaration makes the variable inline, we may need to add it to
4155  // UndefinedButUsed.
4156  if (!Old->isInline() && New->isInline() && Old->isUsed(false) &&
4157  !Old->getDefinition() && !New->isThisDeclarationADefinition())
4158  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
4159  SourceLocation()));
4160 
4161  if (New->getTLSKind() != Old->getTLSKind()) {
4162  if (!Old->getTLSKind()) {
4163  Diag(New->getLocation(), diag::err_thread_non_thread) << New->getDeclName();
4164  Diag(OldLocation, PrevDiag);
4165  } else if (!New->getTLSKind()) {
4166  Diag(New->getLocation(), diag::err_non_thread_thread) << New->getDeclName();
4167  Diag(OldLocation, PrevDiag);
4168  } else {
4169  // Do not allow redeclaration to change the variable between requiring
4170  // static and dynamic initialization.
4171  // FIXME: GCC allows this, but uses the TLS keyword on the first
4172  // declaration to determine the kind. Do we need to be compatible here?
4173  Diag(New->getLocation(), diag::err_thread_thread_different_kind)
4174  << New->getDeclName() << (New->getTLSKind() == VarDecl::TLS_Dynamic);
4175  Diag(OldLocation, PrevDiag);
4176  }
4177  }
4178 
4179  // C++ doesn't have tentative definitions, so go right ahead and check here.
4180  if (getLangOpts().CPlusPlus &&
4182  if (Old->isStaticDataMember() && Old->getCanonicalDecl()->isInline() &&
4183  Old->getCanonicalDecl()->isConstexpr()) {
4184  // This definition won't be a definition any more once it's been merged.
4185  Diag(New->getLocation(),
4186  diag::warn_deprecated_redundant_constexpr_static_def);
4187  } else if (VarDecl *Def = Old->getDefinition()) {
4188  if (checkVarDeclRedefinition(Def, New))
4189  return;
4190  }
4191  }
4192 
4193  if (haveIncompatibleLanguageLinkages(Old, New)) {
4194  Diag(New->getLocation(), diag::err_different_language_linkage) << New;
4195  Diag(OldLocation, PrevDiag);
4196  New->setInvalidDecl();
4197  return;
4198  }
4199 
4200  // Merge "used" flag.
4201  if (Old->getMostRecentDecl()->isUsed(false))
4202  New->setIsUsed();
4203 
4204  // Keep a chain of previous declarations.
4205  New->setPreviousDecl(Old);
4206  if (NewTemplate)
4207  NewTemplate->setPreviousDecl(OldTemplate);
4209 
4210  // Inherit access appropriately.
4211  New->setAccess(Old->getAccess());
4212  if (NewTemplate)
4213  NewTemplate->setAccess(New->getAccess());
4214 
4215  if (Old->isInline())
4216  New->setImplicitlyInline();
4217 }
4218 
4220  SourceManager &SrcMgr = getSourceManager();
4221  auto FNewDecLoc = SrcMgr.getDecomposedLoc(New);
4222  auto FOldDecLoc = SrcMgr.getDecomposedLoc(Old->getLocation());
4223  auto *FNew = SrcMgr.getFileEntryForID(FNewDecLoc.first);
4224  auto *FOld = SrcMgr.getFileEntryForID(FOldDecLoc.first);
4225  auto &HSI = PP.getHeaderSearchInfo();
4226  StringRef HdrFilename =
4227  SrcMgr.getFilename(SrcMgr.getSpellingLoc(Old->getLocation()));
4228 
4229  auto noteFromModuleOrInclude = [&](Module *Mod,
4230  SourceLocation IncLoc) -> bool {
4231  // Redefinition errors with modules are common with non modular mapped
4232  // headers, example: a non-modular header H in module A that also gets
4233  // included directly in a TU. Pointing twice to the same header/definition
4234  // is confusing, try to get better diagnostics when modules is on.
4235  if (IncLoc.isValid()) {
4236  if (Mod) {
4237  Diag(IncLoc, diag::note_redefinition_modules_same_file)
4238  << HdrFilename.str() << Mod->getFullModuleName();
4239  if (!Mod->DefinitionLoc.isInvalid())
4240  Diag(Mod->DefinitionLoc, diag::note_defined_here)
4241  << Mod->getFullModuleName();
4242  } else {
4243  Diag(IncLoc, diag::note_redefinition_include_same_file)
4244  << HdrFilename.str();
4245  }
4246  return true;
4247  }
4248 
4249  return false;
4250  };
4251 
4252  // Is it the same file and same offset? Provide more information on why
4253  // this leads to a redefinition error.
4254  if (FNew == FOld && FNewDecLoc.second == FOldDecLoc.second) {
4255  SourceLocation OldIncLoc = SrcMgr.getIncludeLoc(FOldDecLoc.first);
4256  SourceLocation NewIncLoc = SrcMgr.getIncludeLoc(FNewDecLoc.first);
4257  bool EmittedDiag =
4258  noteFromModuleOrInclude(Old->getOwningModule(), OldIncLoc);
4259  EmittedDiag |= noteFromModuleOrInclude(getCurrentModule(), NewIncLoc);
4260 
4261  // If the header has no guards, emit a note suggesting one.
4262  if (FOld && !HSI.isFileMultipleIncludeGuarded(FOld))
4263  Diag(Old->getLocation(), diag::note_use_ifdef_guards);
4264 
4265  if (EmittedDiag)
4266  return;
4267  }
4268 
4269  // Redefinition coming from different files or couldn't do better above.
4270  if (Old->getLocation().isValid())
4271  Diag(Old->getLocation(), diag::note_previous_definition);
4272 }
4273 
4274 /// We've just determined that \p Old and \p New both appear to be definitions
4275 /// of the same variable. Either diagnose or fix the problem.
4277  if (!hasVisibleDefinition(Old) &&
4278  (New->getFormalLinkage() == InternalLinkage ||
4279  New->isInline() ||
4280  New->getDescribedVarTemplate() ||
4282  New->getDeclContext()->isDependentContext())) {
4283  // The previous definition is hidden, and multiple definitions are
4284  // permitted (in separate TUs). Demote this to a declaration.
4286 
4287  // Make the canonical definition visible.
4288  if (auto *OldTD = Old->getDescribedVarTemplate())
4289  makeMergedDefinitionVisible(OldTD);
4290  makeMergedDefinitionVisible(Old);
4291  return false;
4292  } else {
4293  Diag(New->getLocation(), diag::err_redefinition) << New;
4294  notePreviousDefinition(Old, New->getLocation());
4295  New->setInvalidDecl();
4296  return true;
4297  }
4298 }
4299 
4300 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
4301 /// no declarator (e.g. "struct foo;") is parsed.
4302 Decl *
4304  RecordDecl *&AnonRecord) {
4305  return ParsedFreeStandingDeclSpec(S, AS, DS, MultiTemplateParamsArg(), false,
4306  AnonRecord);
4307 }
4308 
4309 // The MS ABI changed between VS2013 and VS2015 with regard to numbers used to
4310 // disambiguate entities defined in different scopes.
4311 // While the VS2015 ABI fixes potential miscompiles, it is also breaks
4312 // compatibility.
4313 // We will pick our mangling number depending on which version of MSVC is being
4314 // targeted.
4315 static unsigned getMSManglingNumber(const LangOptions &LO, Scope *S) {
4317  ? S->getMSCurManglingNumber()
4318  : S->getMSLastManglingNumber();
4319 }
4320 
4321 void Sema::handleTagNumbering(const TagDecl *Tag, Scope *TagScope) {
4322  if (!Context.getLangOpts().CPlusPlus)
4323  return;
4324 
4325  if (isa<CXXRecordDecl>(Tag->getParent())) {
4326  // If this tag is the direct child of a class, number it if
4327  // it is anonymous.
4328  if (!Tag->getName().empty() || Tag->getTypedefNameForAnonDecl())
4329  return;
4330  MangleNumberingContext &MCtx =
4331  Context.getManglingNumberContext(Tag->getParent());
4332  Context.setManglingNumber(
4333  Tag, MCtx.getManglingNumber(
4334  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
4335  return;
4336  }
4337 
4338  // If this tag isn't a direct child of a class, number it if it is local.
4339  MangleNumberingContext *MCtx;
4340  Decl *ManglingContextDecl;
4341  std::tie(MCtx, ManglingContextDecl) =
4342  getCurrentMangleNumberContext(Tag->getDeclContext());
4343  if (MCtx) {
4344  Context.setManglingNumber(
4345  Tag, MCtx->getManglingNumber(
4346  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
4347  }
4348 }
4349 
4351  TypedefNameDecl *NewTD) {
4352  if (TagFromDeclSpec->isInvalidDecl())
4353  return;
4354 
4355  // Do nothing if the tag already has a name for linkage purposes.
4356  if (TagFromDeclSpec->hasNameForLinkage())
4357  return;
4358 
4359  // A well-formed anonymous tag must always be a TUK_Definition.
4360  assert(TagFromDeclSpec->isThisDeclarationADefinition());
4361 
4362  // The type must match the tag exactly; no qualifiers allowed.
4363  if (!Context.hasSameType(NewTD->getUnderlyingType(),
4364  Context.getTagDeclType(TagFromDeclSpec))) {
4365  if (getLangOpts().CPlusPlus)
4366  Context.addTypedefNameForUnnamedTagDecl(TagFromDeclSpec, NewTD);
4367  return;
4368  }
4369 
4370  // If we've already computed linkage for the anonymous tag, then
4371  // adding a typedef name for the anonymous decl can change that
4372  // linkage, which might be a serious problem. Diagnose this as
4373  // unsupported and ignore the typedef name. TODO: we should
4374  // pursue this as a language defect and establish a formal rule
4375  // for how to handle it.
4376  if (TagFromDeclSpec->hasLinkageBeenComputed()) {
4377  Diag(NewTD->getLocation(), diag::err_typedef_changes_linkage);
4378 
4379  SourceLocation tagLoc = TagFromDeclSpec->getInnerLocStart();
4380  tagLoc = getLocForEndOfToken(tagLoc);
4381 
4382  llvm::SmallString<40> textToInsert;
4383  textToInsert += ' ';
4384  textToInsert += NewTD->getIdentifier()->getName();
4385  Diag(tagLoc, diag::note_typedef_changes_linkage)
4386  << FixItHint::CreateInsertion(tagLoc, textToInsert);
4387  return;
4388  }
4389 
4390  // Otherwise, set this is the anon-decl typedef for the tag.
4391  TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
4392 }
4393 
4395  switch (T) {
4396  case DeclSpec::TST_class:
4397  return 0;
4398  case DeclSpec::TST_struct:
4399  return 1;
4401  return 2;
4402  case DeclSpec::TST_union:
4403  return 3;
4404  case DeclSpec::TST_enum:
4405  return 4;
4406  default:
4407  llvm_unreachable("unexpected type specifier");
4408  }
4409 }
4410 
4411 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
4412 /// no declarator (e.g. "struct foo;") is parsed. It also accepts template
4413 /// parameters to cope with template friend declarations.
4414 Decl *
4416  MultiTemplateParamsArg TemplateParams,
4417  bool IsExplicitInstantiation,
4418  RecordDecl *&AnonRecord) {
4419  Decl *TagD = nullptr;
4420  TagDecl *Tag = nullptr;
4421  if (DS.getTypeSpecType() == DeclSpec::TST_class ||
4426  TagD = DS.getRepAsDecl();
4427 
4428  if (!TagD) // We probably had an error
4429  return nullptr;
4430 
4431  // Note that the above type specs guarantee that the
4432  // type rep is a Decl, whereas in many of the others
4433  // it's a Type.
4434  if (isa<TagDecl>(TagD))
4435  Tag = cast<TagDecl>(TagD);
4436  else if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(TagD))
4437  Tag = CTD->getTemplatedDecl();
4438  }
4439 
4440  if (Tag) {
4441  handleTagNumbering(Tag, S);
4442  Tag->setFreeStanding();
4443  if (Tag->isInvalidDecl())
4444  return Tag;
4445  }
4446 
4447  if (unsigned TypeQuals = DS.getTypeQualifiers()) {
4448  // Enforce C99 6.7.3p2: "Types other than pointer types derived from object
4449  // or incomplete types shall not be restrict-qualified."
4450  if (TypeQuals & DeclSpec::TQ_restrict)
4451  Diag(DS.getRestrictSpecLoc(),
4452  diag::err_typecheck_invalid_restrict_not_pointer_noarg)
4453  << DS.getSourceRange();
4454  }
4455 
4456  if (DS.isInlineSpecified())
4457  Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
4458  << getLangOpts().CPlusPlus17;
4459 
4460  if (DS.hasConstexprSpecifier()) {
4461  // C++0x [dcl.constexpr]p1: constexpr can only be applied to declarations
4462  // and definitions of functions and variables.
4463  // C++2a [dcl.constexpr]p1: The consteval specifier shall be applied only to
4464  // the declaration of a function or function template
4465  if (Tag)
4466  Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
4468  << DS.getConstexprSpecifier();
4469  else
4470  Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_wrong_decl_kind)
4471  << DS.getConstexprSpecifier();
4472  // Don't emit warnings after this error.
4473  return TagD;
4474  }
4475 
4476  DiagnoseFunctionSpecifiers(DS);
4477 
4478  if (DS.isFriendSpecified()) {
4479  // If we're dealing with a decl but not a TagDecl, assume that
4480  // whatever routines created it handled the friendship aspect.
4481  if (TagD && !Tag)
4482  return nullptr;
4483  return ActOnFriendTypeDecl(S, DS, TemplateParams);
4484  }
4485 
4486  const CXXScopeSpec &SS = DS.getTypeSpecScope();
4487  bool IsExplicitSpecialization =
4488  !TemplateParams.empty() && TemplateParams.back()->size() == 0;
4489  if (Tag && SS.isNotEmpty() && !Tag->isCompleteDefinition() &&
4490  !IsExplicitInstantiation && !IsExplicitSpecialization &&
4491  !isa<ClassTemplatePartialSpecializationDecl>(Tag)) {
4492  // Per C++ [dcl.type.elab]p1, a class declaration cannot have a
4493  // nested-name-specifier unless it is an explicit instantiation
4494  // or an explicit specialization.
4495  //
4496  // FIXME: We allow class template partial specializations here too, per the
4497  // obvious intent of DR1819.
4498  //
4499  // Per C++ [dcl.enum]p1, an opaque-enum-declaration can't either.
4500  Diag(SS.getBeginLoc(), diag::err_standalone_class_nested_name_specifier)
4502  return nullptr;
4503  }
4504 
4505  // Track whether this decl-specifier declares anything.
4506  bool DeclaresAnything = true;
4507 
4508  // Handle anonymous struct definitions.
4509  if (RecordDecl *Record = dyn_cast_or_null<RecordDecl>(Tag)) {
4510  if (!Record->getDeclName() && Record->isCompleteDefinition() &&
4512  if (getLangOpts().CPlusPlus ||
4513  Record->getDeclContext()->isRecord()) {
4514  // If CurContext is a DeclContext that can contain statements,
4515  // RecursiveASTVisitor won't visit the decls that
4516  // BuildAnonymousStructOrUnion() will put into CurContext.
4517  // Also store them here so that they can be part of the
4518  // DeclStmt that gets created in this case.
4519  // FIXME: Also return the IndirectFieldDecls created by
4520  // BuildAnonymousStructOr union, for the same reason?
4521  if (CurContext->isFunctionOrMethod())
4522  AnonRecord = Record;
4523  return BuildAnonymousStructOrUnion(S, DS, AS, Record,
4524  Context.getPrintingPolicy());
4525  }
4526 
4527  DeclaresAnything = false;
4528  }
4529  }
4530 
4531  // C11 6.7.2.1p2:
4532  // A struct-declaration that does not declare an anonymous structure or
4533  // anonymous union shall contain a struct-declarator-list.
4534  //
4535  // This rule also existed in C89 and C99; the grammar for struct-declaration
4536  // did not permit a struct-declaration without a struct-declarator-list.
4537  if (!getLangOpts().CPlusPlus && CurContext->isRecord() &&
4539  // Check for Microsoft C extension: anonymous struct/union member.
4540  // Handle 2 kinds of anonymous struct/union:
4541  // struct STRUCT;
4542  // union UNION;
4543  // and
4544  // STRUCT_TYPE; <- where STRUCT_TYPE is a typedef struct.
4545  // UNION_TYPE; <- where UNION_TYPE is a typedef union.
4546  if ((Tag && Tag->getDeclName()) ||
4548  RecordDecl *Record = nullptr;
4549  if (Tag)
4550  Record = dyn_cast<RecordDecl>(Tag);
4551  else if (const RecordType *RT =
4553  Record = RT->getDecl();
4554  else if (const RecordType *UT = DS.getRepAsType().get()->getAsUnionType())
4555  Record = UT->getDecl();
4556 
4557  if (Record && getLangOpts().MicrosoftExt) {
4558  Diag(DS.getBeginLoc(), diag::ext_ms_anonymous_record)
4559  << Record->isUnion() << DS.getSourceRange();
4560  return BuildMicrosoftCAnonymousStruct(S, DS, Record);
4561  }
4562 
4563  DeclaresAnything = false;
4564  }
4565  }
4566 
4567  // Skip all the checks below if we have a type error.
4568  if (DS.getTypeSpecType() == DeclSpec::TST_error ||
4569  (TagD && TagD->isInvalidDecl()))
4570  return TagD;
4571 
4572  if (getLangOpts().CPlusPlus &&
4574  if (EnumDecl *Enum = dyn_cast_or_null<EnumDecl>(Tag))
4575  if (Enum->enumerator_begin() == Enum->enumerator_end() &&
4576  !Enum->getIdentifier() && !Enum->isInvalidDecl())
4577  DeclaresAnything = false;
4578 
4579  if (!DS.isMissingDeclaratorOk()) {
4580  // Customize diagnostic for a typedef missing a name.
4582  Diag(DS.getBeginLoc(), diag::ext_typedef_without_a_name)
4583  << DS.getSourceRange();
4584  else
4585  DeclaresAnything = false;
4586  }
4587 
4588  if (DS.isModulePrivateSpecified() &&
4589  Tag && Tag->getDeclContext()->isFunctionOrMethod())
4590  Diag(DS.getModulePrivateSpecLoc(), diag::err_module_private_local_class)
4591  << Tag->getTagKind()
4593 
4594  ActOnDocumentableDecl(TagD);
4595 
4596  // C 6.7/2:
4597  // A declaration [...] shall declare at least a declarator [...], a tag,
4598  // or the members of an enumeration.
4599  // C++ [dcl.dcl]p3:
4600  // [If there are no declarators], and except for the declaration of an
4601  // unnamed bit-field, the decl-specifier-seq shall introduce one or more
4602  // names into the program, or shall redeclare a name introduced by a
4603  // previous declaration.
4604  if (!DeclaresAnything) {
4605  // In C, we allow this as a (popular) extension / bug. Don't bother
4606  // producing further diagnostics for redundant qualifiers after this.
4607  Diag(DS.getBeginLoc(), diag::ext_no_declarators) << DS.getSourceRange();
4608  return TagD;
4609  }
4610 
4611  // C++ [dcl.stc]p1:
4612  // If a storage-class-specifier appears in a decl-specifier-seq, [...] the
4613  // init-declarator-list of the declaration shall not be empty.
4614  // C++ [dcl.fct.spec]p1:
4615  // If a cv-qualifier appears in a decl-specifier-seq, the
4616  // init-declarator-list of the declaration shall not be empty.
4617  //
4618  // Spurious qualifiers here appear to be valid in C.
4619  unsigned DiagID = diag::warn_standalone_specifier;
4620  if (getLangOpts().CPlusPlus)
4621  DiagID = diag::ext_standalone_specifier;
4622 
4623  // Note that a linkage-specification sets a storage class, but
4624  // 'extern "C" struct foo;' is actually valid and not theoretically
4625  // useless.
4626  if (DeclSpec::SCS SCS = DS.getStorageClassSpec()) {
4627  if (SCS == DeclSpec::SCS_mutable)
4628  // Since mutable is not a viable storage class specifier in C, there is
4629  // no reason to treat it as an extension. Instead, diagnose as an error.
4630  Diag(DS.getStorageClassSpecLoc(), diag::err_mutable_nonmember);
4631  else if (!DS.isExternInLinkageSpec() && SCS != DeclSpec::SCS_typedef)
4632  Diag(DS.getStorageClassSpecLoc(), DiagID)
4634  }
4635 
4636  if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
4637  Diag(DS.getThreadStorageClassSpecLoc(), DiagID)
4638  << DeclSpec::getSpecifierName(TSCS);
4639  if (DS.getTypeQualifiers()) {
4641  Diag(DS.getConstSpecLoc(), DiagID) << "const";
4643  Diag(DS.getConstSpecLoc(), DiagID) << "volatile";
4644  // Restrict is covered above.
4646  Diag(DS.getAtomicSpecLoc(), DiagID) << "_Atomic";
4648  Diag(DS.getUnalignedSpecLoc(), DiagID) << "__unaligned";
4649  }
4650 
4651  // Warn about ignored type attributes, for example:
4652  // __attribute__((aligned)) struct A;
4653  // Attributes should be placed after tag to apply to type declaration.
4654  if (!DS.getAttributes().empty()) {
4655  DeclSpec::TST TypeSpecType = DS.getTypeSpecType();
4656  if (TypeSpecType == DeclSpec::TST_class ||
4657  TypeSpecType == DeclSpec::TST_struct ||
4658  TypeSpecType == DeclSpec::TST_interface ||
4659  TypeSpecType == DeclSpec::TST_union ||
4660  TypeSpecType == DeclSpec::TST_enum) {
4661  for (const ParsedAttr &AL : DS.getAttributes())
4662  Diag(AL.getLoc(), diag::warn_declspec_attribute_ignored)
4663  << AL << GetDiagnosticTypeSpecifierID(TypeSpecType);
4664  }
4665  }
4666 
4667  return TagD;
4668 }
4669 
4670 /// We are trying to inject an anonymous member into the given scope;
4671 /// check if there's an existing declaration that can't be overloaded.
4672 ///
4673 /// \return true if this is a forbidden redeclaration
4674 static bool CheckAnonMemberRedeclaration(Sema &SemaRef,
4675  Scope *S,
4676  DeclContext *Owner,
4677  DeclarationName Name,
4678  SourceLocation NameLoc,
4679  bool IsUnion) {
4680  LookupResult R(SemaRef, Name, NameLoc, Sema::LookupMemberName,
4682  if (!SemaRef.LookupName(R, S)) return false;
4683 
4684  // Pick a representative declaration.
4686  assert(PrevDecl && "Expected a non-null Decl");
4687 
4688  if (!SemaRef.isDeclInScope(PrevDecl, Owner, S))
4689  return false;
4690 
4691  SemaRef.Diag(NameLoc, diag::err_anonymous_record_member_redecl)
4692  << IsUnion << Name;
4693  SemaRef.Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
4694 
4695  return true;
4696 }
4697 
4698 /// InjectAnonymousStructOrUnionMembers - Inject the members of the
4699 /// anonymous struct or union AnonRecord into the owning context Owner
4700 /// and scope S. This routine will be invoked just after we realize
4701 /// that an unnamed union or struct is actually an anonymous union or
4702 /// struct, e.g.,
4703 ///
4704 /// @code
4705 /// union {
4706 /// int i;
4707 /// float f;
4708 /// }; // InjectAnonymousStructOrUnionMembers called here to inject i and
4709 /// // f into the surrounding scope.x
4710 /// @endcode
4711 ///
4712 /// This routine is recursive, injecting the names of nested anonymous
4713 /// structs/unions into the owning context and scope as well.
4714 static bool
4716  RecordDecl *AnonRecord, AccessSpecifier AS,
4717  SmallVectorImpl<NamedDecl *> &Chaining) {
4718  bool Invalid = false;
4719 
4720  // Look every FieldDecl and IndirectFieldDecl with a name.
4721  for (auto *D : AnonRecord->decls()) {
4722  if ((isa<FieldDecl>(D) || isa<IndirectFieldDecl>(D)) &&
4723  cast<NamedDecl>(D)->getDeclName()) {
4724  ValueDecl *VD = cast<ValueDecl>(D);
4725  if (CheckAnonMemberRedeclaration(SemaRef, S, Owner, VD->getDeclName(),
4726  VD->getLocation(),
4727  AnonRecord->isUnion())) {
4728  // C++ [class.union]p2:
4729  // The names of the members of an anonymous union shall be
4730  // distinct from the names of any other entity in the
4731  // scope in which the anonymous union is declared.
4732  Invalid = true;
4733  } else {
4734  // C++ [class.union]p2:
4735  // For the purpose of name lookup, after the anonymous union
4736  // definition, the members of the anonymous union are
4737  // considered to have been defined in the scope in which the
4738  // anonymous union is declared.
4739  unsigned OldChainingSize = Chaining.size();
4740  if (IndirectFieldDecl *IF = dyn_cast<IndirectFieldDecl>(VD))
4741  Chaining.append(IF->chain_begin(), IF->chain_end());
4742  else
4743  Chaining.push_back(VD);
4744 
4745  assert(Chaining.size() >= 2);
4746  NamedDecl **NamedChain =
4747  new (SemaRef.Context)NamedDecl*[Chaining.size()];
4748  for (unsigned i = 0; i < Chaining.size(); i++)
4749  NamedChain[i] = Chaining[i];
4750 
4752  SemaRef.Context, Owner, VD->getLocation(), VD->getIdentifier(),
4753  VD->getType(), {NamedChain, Chaining.size()});
4754 
4755  for (const auto *Attr : VD->attrs())
4756  IndirectField->addAttr(Attr->clone(SemaRef.Context));
4757 
4758  IndirectField->setAccess(AS);
4759  IndirectField->setImplicit();
4760  SemaRef.PushOnScopeChains(IndirectField, S);
4761 
4762  // That includes picking up the appropriate access specifier.
4763  if (AS != AS_none) IndirectField->setAccess(AS);
4764 
4765  Chaining.resize(OldChainingSize);
4766  }
4767  }
4768  }
4769 
4770  return Invalid;
4771 }
4772 
4773 /// StorageClassSpecToVarDeclStorageClass - Maps a DeclSpec::SCS to
4774 /// a VarDecl::StorageClass. Any error reporting is up to the caller:
4775 /// illegal input values are mapped to SC_None.
4776 static StorageClass
4778  DeclSpec::SCS StorageClassSpec = DS.getStorageClassSpec();
4779  assert(StorageClassSpec != DeclSpec::SCS_typedef &&
4780  "Parser allowed 'typedef' as storage class VarDecl.");
4781  switch (StorageClassSpec) {
4782  case DeclSpec::SCS_unspecified: return SC_None;
4783  case DeclSpec::SCS_extern:
4784  if (DS.isExternInLinkageSpec())
4785  return SC_None;
4786  return SC_Extern;
4787  case DeclSpec::SCS_static: return SC_Static;
4788  case DeclSpec::SCS_auto: return SC_Auto;
4789  case DeclSpec::SCS_register: return SC_Register;
4791  // Illegal SCSs map to None: error reporting is up to the caller.
4792  case DeclSpec::SCS_mutable: // Fall through.
4793  case DeclSpec::SCS_typedef: return SC_None;
4794  }
4795  llvm_unreachable("unknown storage class specifier");
4796 }
4797 
4799  assert(Record->hasInClassInitializer());
4800 
4801  for (const auto *I : Record->decls()) {
4802  const auto *FD = dyn_cast<FieldDecl>(I);
4803  if (const auto *IFD = dyn_cast<IndirectFieldDecl>(I))
4804  FD = IFD->getAnonField();
4805  if (FD && FD->hasInClassInitializer())
4806  return FD->getLocation();
4807  }
4808 
4809  llvm_unreachable("couldn't find in-class initializer");
4810 }
4811 
4813  SourceLocation DefaultInitLoc) {
4814  if (!Parent->isUnion() || !Parent->hasInClassInitializer())
4815  return;
4816 
4817  S.Diag(DefaultInitLoc, diag::err_multiple_mem_union_initialization);
4818  S.Diag(findDefaultInitializer(Parent), diag::note_previous_initializer) << 0;
4819 }
4820 
4822  CXXRecordDecl *AnonUnion) {
4823  if (!Parent->isUnion() || !Parent->hasInClassInitializer())
4824  return;
4825 
4826  checkDuplicateDefaultInit(S, Parent, findDefaultInitializer(AnonUnion));
4827 }
4828 
4829 /// BuildAnonymousStructOrUnion - Handle the declaration of an
4830 /// anonymous structure or union. Anonymous unions are a C++ feature
4831 /// (C++ [class.union]) and a C11 feature; anonymous structures
4832 /// are a C11 feature and GNU C++ extension.
4834  AccessSpecifier AS,
4835  RecordDecl *Record,
4836  const PrintingPolicy &Policy) {
4837  DeclContext *Owner = Record->getDeclContext();
4838 
4839  // Diagnose whether this anonymous struct/union is an extension.
4840  if (Record->isUnion() && !getLangOpts().CPlusPlus && !getLangOpts().C11)
4841  Diag(Record->getLocation(), diag::ext_anonymous_union);
4842  else if (!Record->isUnion() && getLangOpts().CPlusPlus)
4843  Diag(Record->getLocation(), diag::ext_gnu_anonymous_struct);
4844  else if (!Record->isUnion() && !getLangOpts().C11)
4845  Diag(Record->getLocation(), diag::ext_c11_anonymous_struct);
4846 
4847  // C and C++ require different kinds of checks for anonymous
4848  // structs/unions.
4849  bool Invalid = false;
4850  if (getLangOpts().CPlusPlus) {
4851  const char *PrevSpec = nullptr;
4852  if (Record->isUnion()) {
4853  // C++ [class.union]p6:
4854  // C++17 [class.union.anon]p2:
4855  // Anonymous unions declared in a named namespace or in the
4856  // global namespace shall be declared static.
4857  unsigned DiagID;
4858  DeclContext *OwnerScope = Owner->getRedeclContext();
4860  (OwnerScope->isTranslationUnit() ||
4861  (OwnerScope->isNamespace() &&
4862  !cast<NamespaceDecl>(OwnerScope)->isAnonymousNamespace()))) {
4863  Diag(Record->getLocation(), diag::err_anonymous_union_not_static)
4864  << FixItHint::CreateInsertion(Record->getLocation(), "static ");
4865 
4866  // Recover by adding 'static'.
4868  PrevSpec, DiagID, Policy);
4869  }
4870  // C++ [class.union]p6:
4871  // A storage class is not allowed in a declaration of an
4872  // anonymous union in a class scope.
4874  isa<RecordDecl>(Owner)) {
4876  diag::err_anonymous_union_with_storage_spec)
4878 
4879  // Recover by removing the storage specifier.
4881  SourceLocation(),
4882  PrevSpec, DiagID, Context.getPrintingPolicy());
4883  }
4884  }
4885 
4886  // Ignore const/volatile/restrict qualifiers.
4887  if (DS.getTypeQualifiers()) {
4889  Diag(DS.getConstSpecLoc(), diag::ext_anonymous_struct_union_qualified)
4890  << Record->isUnion() << "const"
4893  Diag(DS.getVolatileSpecLoc(),
4894  diag::ext_anonymous_struct_union_qualified)
4895  << Record->isUnion() << "volatile"
4898  Diag(DS.getRestrictSpecLoc(),
4899  diag::ext_anonymous_struct_union_qualified)
4900  << Record->isUnion() << "restrict"
4903  Diag(DS.getAtomicSpecLoc(),
4904  diag::ext_anonymous_struct_union_qualified)
4905  << Record->isUnion() << "_Atomic"
4909  diag::ext_anonymous_struct_union_qualified)
4910  << Record->isUnion() << "__unaligned"
4912 
4913  DS.ClearTypeQualifiers();
4914  }
4915 
4916  // C++ [class.union]p2:
4917  // The member-specification of an anonymous union shall only
4918  // define non-static data members. [Note: nested types and
4919  // functions cannot be declared within an anonymous union. ]
4920  for (auto *Mem : Record->decls()) {
4921  if (auto *FD = dyn_cast<FieldDecl>(Mem)) {
4922  // C++ [class.union]p3:
4923  // An anonymous union shall not have private or protected
4924  // members (clause 11).
4925  assert(FD->getAccess() != AS_none);
4926  if (FD->getAccess() != AS_public) {
4927  Diag(FD->getLocation(), diag::err_anonymous_record_nonpublic_member)
4928  << Record->isUnion() << (FD->getAccess() == AS_protected);
4929  Invalid = true;
4930  }
4931 
4932  // C++ [class.union]p1
4933  // An object of a class with a non-trivial constructor, a non-trivial
4934  // copy constructor, a non-trivial destructor, or a non-trivial copy
4935  // assignment operator cannot be a member of a union, nor can an
4936  // array of such objects.
4937  if (CheckNontrivialField(FD))
4938  Invalid = true;
4939  } else if (Mem->isImplicit()) {
4940  // Any implicit members are fine.
4941  } else if (isa<TagDecl>(Mem) && Mem->getDeclContext() != Record) {
4942  // This is a type that showed up in an
4943  // elaborated-type-specifier inside the anonymous struct or
4944  // union, but which actually declares a type outside of the
4945  // anonymous struct or union. It's okay.
4946  } else if (auto *MemRecord = dyn_cast<RecordDecl>(Mem)) {
4947  if (!MemRecord->isAnonymousStructOrUnion() &&
4948  MemRecord->getDeclName()) {
4949  // Visual C++ allows type definition in anonymous struct or union.
4950  if (getLangOpts().MicrosoftExt)
4951  Diag(MemRecord->getLocation(), diag::ext_anonymous_record_with_type)
4952  << Record->isUnion();
4953  else {
4954  // This is a nested type declaration.
4955  Diag(MemRecord->getLocation(), diag::err_anonymous_record_with_type)
4956  << Record->isUnion();
4957  Invalid = true;
4958  }
4959  } else {
4960  // This is an anonymous type definition within another anonymous type.
4961  // This is a popular extension, provided by Plan9, MSVC and GCC, but
4962  // not part of standard C++.
4963  Diag(MemRecord->getLocation(),
4964  diag::ext_anonymous_record_with_anonymous_type)
4965  << Record->isUnion();
4966  }
4967  } else if (isa<AccessSpecDecl>(Mem)) {
4968  // Any access specifier is fine.
4969  } else if (isa<StaticAssertDecl>(Mem)) {
4970  // In C++1z, static_assert declarations are also fine.
4971  } else {
4972  // We have something that isn't a non-static data
4973  // member. Complain about it.
4974  unsigned DK = diag::err_anonymous_record_bad_member;
4975  if (isa<TypeDecl>(Mem))
4976  DK = diag::err_anonymous_record_with_type;
4977  else if (isa<FunctionDecl>(Mem))
4978  DK = diag::err_anonymous_record_with_function;
4979  else if (isa<VarDecl>(Mem))
4980  DK = diag::err_anonymous_record_with_static;
4981 
4982  // Visual C++ allows type definition in anonymous struct or union.
4983  if (getLangOpts().MicrosoftExt &&
4984  DK == diag::err_anonymous_record_with_type)
4985  Diag(Mem->getLocation(), diag::ext_anonymous_record_with_type)
4986  << Record->isUnion();
4987  else {
4988  Diag(Mem->getLocation(), DK) << Record->isUnion();
4989  Invalid = true;
4990  }
4991  }
4992  }
4993 
4994  // C++11 [class.union]p8 (DR1460):
4995  // At most one variant member of a union may have a
4996  // brace-or-equal-initializer.
4997  if (cast<CXXRecordDecl>(Record)->hasInClassInitializer() &&
4998  Owner->isRecord())
4999  checkDuplicateDefaultInit(*this, cast<CXXRecordDecl>(Owner),
5000  cast<CXXRecordDecl>(Record));
5001  }
5002 
5003  if (!Record->isUnion() && !Owner->isRecord()) {
5004  Diag(Record->getLocation(), diag::err_anonymous_struct_not_member)
5005  << getLangOpts().CPlusPlus;
5006  Invalid = true;
5007  }
5008 
5009  // C++ [dcl.dcl]p3:
5010  // [If there are no declarators], and except for the declaration of an
5011  // unnamed bit-field, the decl-specifier-seq shall introduce one or more
5012  // names into the program
5013  // C++ [class.mem]p2:
5014  // each such member-declaration shall either declare at least one member
5015  // name of the class or declare at least one unnamed bit-field
5016  //
5017  // For C this is an error even for a named struct, and is diagnosed elsewhere.
5018  if (getLangOpts().CPlusPlus && Record->field_empty())
5019  Diag(DS.getBeginLoc(), diag::ext_no_declarators) << DS.getSourceRange();
5020 
5021  // Mock up a declarator.
5023  TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
5024  assert(TInfo && "couldn't build declarator info for anonymous struct/union");
5025 
5026  // Create a declaration for this anonymous struct/union.
5027  NamedDecl *Anon = nullptr;
5028  if (RecordDecl *OwningClass = dyn_cast<RecordDecl>(Owner)) {
5029  Anon = FieldDecl::Create(
5030  Context, OwningClass, DS.getBeginLoc(), Record->getLocation(),
5031  /*IdentifierInfo=*/nullptr, Context.getTypeDeclType(Record), TInfo,
5032  /*BitWidth=*/nullptr, /*Mutable=*/false,
5033  /*InitStyle=*/ICIS_NoInit);
5034  Anon->setAccess(AS);
5035  if (getLangOpts().CPlusPlus)
5036  FieldCollector->Add(cast<FieldDecl>(Anon));
5037  } else {
5038  DeclSpec::SCS SCSpec = DS.getStorageClassSpec();
5040  if (SCSpec == DeclSpec::SCS_mutable) {
5041  // mutable can only appear on non-static class members, so it's always
5042  // an error here
5043  Diag(Record->getLocation(), diag::err_mutable_nonmember);
5044  Invalid = true;
5045  SC = SC_None;
5046  }
5047 
5048  Anon = VarDecl::Create(Context, Owner, DS.getBeginLoc(),
5049  Record->getLocation(), /*IdentifierInfo=*/nullptr,
5050  Context.getTypeDeclType(Record), TInfo, SC);
5051 
5052  // Default-initialize the implicit variable. This initialization will be
5053  // trivial in almost all cases, except if a union member has an in-class
5054  // initializer:
5055  // union { int n = 0; };
5056  ActOnUninitializedDecl(Anon);
5057  }
5058  Anon->setImplicit();
5059 
5060  // Mark this as an anonymous struct/union type.
5061  Record->setAnonymousStructOrUnion(true);
5062 
5063  // Add the anonymous struct/union object to the current
5064  // context. We'll be referencing this object when we refer to one of
5065  // its members.
5066  Owner->addDecl(Anon);
5067 
5068  // Inject the members of the anonymous struct/union into the owning
5069  // context and into the identifier resolver chain for name lookup
5070  // purposes.
5072  Chain.push_back(Anon);
5073 
5074  if (InjectAnonymousStructOrUnionMembers(*this, S, Owner, Record, AS, Chain))
5075  Invalid = true;
5076 
5077  if (VarDecl *NewVD = dyn_cast<VarDecl>(Anon)) {
5078  if (getLangOpts().CPlusPlus && NewVD->isStaticLocal()) {
5079  MangleNumberingContext *MCtx;
5080  Decl *ManglingContextDecl;
5081  std::tie(MCtx, ManglingContextDecl) =
5082  getCurrentMangleNumberContext(NewVD->getDeclContext());
5083  if (MCtx) {
5084  Context.setManglingNumber(
5085  NewVD, MCtx->getManglingNumber(
5086  NewVD, getMSManglingNumber(getLangOpts(), S)));
5087  Context.setStaticLocalNumber(NewVD, MCtx->getStaticLocalNumber(NewVD));
5088  }
5089  }
5090  }
5091 
5092  if (Invalid)
5093  Anon->setInvalidDecl();
5094 
5095  return Anon;
5096 }
5097 
5098 /// BuildMicrosoftCAnonymousStruct - Handle the declaration of an
5099 /// Microsoft C anonymous structure.
5100 /// Ref: http://msdn.microsoft.com/en-us/library/z2cx9y4f.aspx
5101 /// Example:
5102 ///
5103 /// struct A { int a; };
5104 /// struct B { struct A; int b; };
5105 ///
5106 /// void foo() {
5107 /// B var;
5108 /// var.a = 3;
5109 /// }
5110 ///
5112  RecordDecl *Record) {
5113  assert(Record && "expected a record!");
5114 
5115  // Mock up a declarator.
5117  TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
5118  assert(TInfo && "couldn't build declarator info for anonymous struct");
5119 
5120  auto *ParentDecl = cast<RecordDecl>(CurContext);
5121  QualType RecTy = Context.getTypeDeclType(Record);
5122 
5123  // Create a declaration for this anonymous struct.
5124  NamedDecl *Anon =
5125  FieldDecl::Create(Context, ParentDecl, DS.getBeginLoc(), DS.getBeginLoc(),
5126  /*IdentifierInfo=*/nullptr, RecTy, TInfo,
5127  /*BitWidth=*/nullptr, /*Mutable=*/false,
5128  /*InitStyle=*/ICIS_NoInit);
5129  Anon->setImplicit();
5130 
5131  // Add the anonymous struct object to the current context.
5132  CurContext->addDecl(Anon);
5133 
5134  // Inject the members of the anonymous struct into the current
5135  // context and into the identifier resolver chain for name lookup
5136  // purposes.
5138  Chain.push_back(Anon);
5139 
5140  RecordDecl *RecordDef = Record->getDefinition();
5141  if (RequireCompleteType(Anon->getLocation(), RecTy,
5142  diag::err_field_incomplete) ||
5143  InjectAnonymousStructOrUnionMembers(*this, S, CurContext, RecordDef,
5144  AS_none, Chain)) {
5145  Anon->setInvalidDecl();
5146  ParentDecl->setInvalidDecl();
5147  }
5148 
5149  return Anon;
5150 }
5151 
5152 /// GetNameForDeclarator - Determine the full declaration name for the
5153 /// given Declarator.
5155  return GetNameFromUnqualifiedId(D.getName());
5156 }
5157 
5158 /// Retrieves the declaration name from a parsed unqualified-id.
5161  DeclarationNameInfo NameInfo;
5162  NameInfo.setLoc(Name.StartLocation);
5163 
5164  switch (Name.getKind()) {
5165 
5168  NameInfo.setName(Name.Identifier);
5169  return NameInfo;
5170 
5172  // C++ [temp.deduct.guide]p3:
5173  // The simple-template-id shall name a class template specialization.
5174  // The template-name shall be the same identifier as the template-name
5175  // of the simple-template-id.
5176  // These together intend to imply that the template-name shall name a
5177  // class template.
5178  // FIXME: template<typename T> struct X {};
5179  // template<typename T> using Y = X<T>;
5180  // Y(int) -> Y<int>;
5181  // satisfies these rules but does not name a class template.
5182  TemplateName TN = Name.TemplateName.get().get();
5183  auto *Template = TN.getAsTemplateDecl();
5184  if (!Template || !isa<ClassTemplateDecl>(Template)) {
5185  Diag(Name.StartLocation,
5186  diag::err_deduction_guide_name_not_class_template)
5187  << (int)getTemplateNameKindForDiagnostics(TN) << TN;
5188  if (Template)
5189  Diag(Template->getLocation(), diag::note_template_decl_here);
5190  return DeclarationNameInfo();
5191  }
5192 
5193  NameInfo.setName(
5194  Context.DeclarationNames.getCXXDeductionGuideName(Template));
5195  return NameInfo;
5196  }
5197 
5199  NameInfo.setName(Context.DeclarationNames.getCXXOperatorName(
5204  = Name.EndLocation.getRawEncoding();
5205  return NameInfo;
5206 
5209  Name.Identifier));
5211  return NameInfo;
5212 
5214  TypeSourceInfo *TInfo;
5215  QualType Ty = GetTypeFromParser(Name.ConversionFunctionId, &TInfo);
5216  if (Ty.isNull())
5217  return DeclarationNameInfo();
5219  Context.getCanonicalType(Ty)));
5220  NameInfo.setNamedTypeInfo(TInfo);
5221  return NameInfo;
5222  }
5223 
5225  TypeSourceInfo *TInfo;
5226  QualType Ty = GetTypeFromParser(Name.ConstructorName, &TInfo);
5227  if (Ty.isNull())
5228  return DeclarationNameInfo();
5230  Context.getCanonicalType(Ty)));
5231  NameInfo.setNamedTypeInfo(TInfo);
5232  return NameInfo;
5233  }
5234 
5236  // In well-formed code, we can only have a constructor
5237  // template-id that refers to the current context, so go there
5238  // to find the actual type being constructed.
5239  CXXRecordDecl *CurClass = dyn_cast<CXXRecordDecl>(CurContext);
5240  if (!CurClass || CurClass->getIdentifier() != Name.TemplateId->Name)
5241  return DeclarationNameInfo();
5242 
5243  // Determine the type of the class being constructed.
5244  QualType CurClassType = Context.getTypeDeclType(CurClass);
5245 
5246  // FIXME: Check two things: that the template-id names the same type as
5247  // CurClassType, and that the template-id does not occur when the name
5248  // was qualified.
5249 
5251  Context.getCanonicalType(CurClassType)));
5252  // FIXME: should we retrieve TypeSourceInfo?
5253  NameInfo.setNamedTypeInfo(nullptr);
5254  return NameInfo;
5255  }
5256 
5258  TypeSourceInfo *TInfo;
5259  QualType Ty = GetTypeFromParser(Name.DestructorName, &TInfo);
5260  if (Ty.isNull())
5261  return DeclarationNameInfo();
5263  Context.getCanonicalType(Ty)));
5264  NameInfo.setNamedTypeInfo(TInfo);
5265  return NameInfo;
5266  }
5267 
5269  TemplateName TName = Name.TemplateId->Template.get();
5270  SourceLocation TNameLoc = Name.TemplateId->TemplateNameLoc;
5271  return Context.getNameForTemplate(TName, TNameLoc);
5272  }
5273 
5274  } // switch (Name.getKind())
5275 
5276  llvm_unreachable("Unknown name kind");
5277 }
5278 
5280  do {
5281  if (Ty->isPointerType() || Ty->isReferenceType())
5282  Ty = Ty->getPointeeType();
5283  else if (Ty->isArrayType())
5284  Ty = Ty->castAsArrayTypeUnsafe()->getElementType();
5285  else
5286  return Ty.withoutLocalFastQualifiers();
5287  } while (true);
5288 }
5289 
5290 /// hasSimilarParameters - Determine whether the C++ functions Declaration
5291 /// and Definition have "nearly" matching parameters. This heuristic is
5292 /// used to improve diagnostics in the case where an out-of-line function
5293 /// definition doesn't match any declaration within the class or namespace.
5294 /// Also sets Params to the list of indices to the parameters that differ
5295 /// between the declaration and the definition. If hasSimilarParameters
5296 /// returns true and Params is empty, then all of the parameters match.
5297 static bool hasSimilarParameters(ASTContext &Context,
5298  FunctionDecl *Declaration,
5299  FunctionDecl *Definition,
5300  SmallVectorImpl<unsigned> &Params) {
5301  Params.clear();
5302  if (Declaration->param_size() != Definition->param_size())
5303  return false;
5304  for (unsigned Idx = 0; Idx < Declaration->param_size(); ++Idx) {
5305  QualType DeclParamTy = Declaration->getParamDecl(Idx)->getType();
5306  QualType DefParamTy = Definition->getParamDecl(Idx)->getType();
5307 
5308  // The parameter types are identical
5309  if (Context.hasSameUnqualifiedType(DefParamTy, DeclParamTy))
5310  continue;
5311 
5312  QualType DeclParamBaseTy = getCoreType(DeclParamTy);
5313  QualType DefParamBaseTy = getCoreType(DefParamTy);
5314  const IdentifierInfo *DeclTyName = DeclParamBaseTy.getBaseTypeIdentifier();
5315  const IdentifierInfo *DefTyName = DefParamBaseTy.getBaseTypeIdentifier();
5316 
5317  if (Context.hasSameUnqualifiedType(DeclParamBaseTy, DefParamBaseTy) ||
5318  (DeclTyName && DeclTyName == DefTyName))
5319  Params.push_back(Idx);
5320  else // The two parameters aren't even close
5321  return false;
5322  }
5323 
5324  return true;
5325 }
5326 
5327 /// NeedsRebuildingInCurrentInstantiation - Checks whether the given
5328 /// declarator needs to be rebuilt in the current instantiation.
5329 /// Any bits of declarator which appear before the name are valid for
5330 /// consideration here. That's specifically the type in the decl spec
5331 /// and the base type in any member-pointer chunks.
5333  DeclarationName Name) {
5334  // The types we specifically need to rebuild are:
5335  // - typenames, typeofs, and decltypes
5336  // - types which will become injected class names
5337  // Of course, we also need to rebuild any type referencing such a
5338  // type. It's safest to just say "dependent", but we call out a
5339  // few cases here.
5340 
5341  DeclSpec &DS = D.getMutableDeclSpec();
5342  switch (DS.getTypeSpecType()) {
5346  case DeclSpec::TST_atomic: {
5347  // Grab the type from the parser.
5348  TypeSourceInfo *TSI = nullptr;
5349  QualType T = S.GetTypeFromParser(DS.getRepAsType(), &TSI);
5350  if (T.isNull() || !T->isDependentType()) break;
5351 
5352  // Make sure there's a type source info. This isn't really much
5353  // of a waste; most dependent types should have type source info
5354  // attached already.
5355  if (!TSI)
5357 
5358  // Rebuild the type in the current instantiation.
5359  TSI = S.RebuildTypeInCurrentInstantiation(TSI, D.getIdentifierLoc(), Name);
5360  if (!TSI) return true;
5361 
5362  // Store the new type back in the decl spec.
5363  ParsedType LocType = S.CreateParsedType(TSI->getType(), TSI);
5364  DS.UpdateTypeRep(LocType);
5365  break;
5366  }
5367 
5369  case DeclSpec::TST_typeofExpr: {
5370  Expr *E = DS.getRepAsExpr();
5372  if (Result.isInvalid()) return true;
5373  DS.UpdateExprRep(Result.get());
5374  break;
5375  }
5376 
5377  default:
5378  // Nothing to do for these decl specs.
5379  break;
5380  }
5381 
5382  // It doesn't matter what order we do this in.
5383  for (unsigned I = 0, E = D.getNumTypeObjects(); I != E; ++I) {
5384  DeclaratorChunk &Chunk = D.getTypeObject(I);
5385 
5386  // The only type information in the declarator which can come
5387  // before the declaration name is the base type of a member
5388  // pointer.
5389  if (Chunk.Kind != DeclaratorChunk::MemberPointer)
5390  continue;
5391 
5392  // Rebuild the scope specifier in-place.
5393  CXXScopeSpec &SS = Chunk.Mem.Scope();
5395  return true;
5396  }
5397 
5398  return false;
5399 }
5400 
5403  Decl *Dcl = HandleDeclarator(S, D, MultiTemplateParamsArg());
5404 
5405  if (OriginalLexicalContext && OriginalLexicalContext->isObjCContainer() &&
5406  Dcl && Dcl->getDeclContext()->isFileContext())
5408 
5409  if (getLangOpts().OpenCL)
5410  setCurrentOpenCLExtensionForDecl(Dcl);
5411 
5412  return Dcl;
5413 }
5414 
5415 /// DiagnoseClassNameShadow - Implement C++ [class.mem]p13:
5416 /// If T is the name of a class, then each of the following shall have a
5417 /// name different from T:
5418 /// - every static data member of class T;
5419 /// - every member function of class T
5420 /// - every member of class T that is itself a type;
5421 /// \returns true if the declaration name violates these rules.
5423  DeclarationNameInfo NameInfo) {
5424  DeclarationName Name = NameInfo.getName();
5425 
5426  CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(DC);
5427  while (Record && Record->isAnonymousStructOrUnion())
5428  Record = dyn_cast<CXXRecordDecl>(Record->getParent());
5429  if (Record && Record->getIdentifier() && Record->getDeclName() == Name) {
5430  Diag(NameInfo.getLoc(), diag::err_member_name_of_class) << Name;
5431  return true;
5432  }
5433 
5434  return false;
5435 }
5436 
5437 /// Diagnose a declaration whose declarator-id has the given
5438 /// nested-name-specifier.
5439 ///
5440 /// \param SS The nested-name-specifier of the declarator-id.
5441 ///
5442 /// \param DC The declaration context to which the nested-name-specifier
5443 /// resolves.
5444 ///
5445 /// \param Name The name of the entity being declared.
5446 ///
5447 /// \param Loc The location of the name of the entity being declared.
5448 ///
5449 /// \param IsTemplateId Whether the name is a (simple-)template-id, and thus
5450 /// we're declaring an explicit / partial specialization / instantiation.
5451 ///
5452 /// \returns true if we cannot safely recover from this error, false otherwise.
5454  DeclarationName Name,
5455  SourceLocation Loc, bool IsTemplateId) {
5456  DeclContext *Cur = CurContext;
5457  while (isa<LinkageSpecDecl>(Cur) || isa<CapturedDecl>(Cur))
5458  Cur = Cur->getParent();
5459 
5460  // If the user provided a superfluous scope specifier that refers back to the
5461  // class in which the entity is already declared, diagnose and ignore it.
5462  //
5463  // class X {
5464  // void X::f();
5465  // };
5466  //
5467  // Note, it was once ill-formed to give redundant qualification in all
5468  // contexts, but that rule was removed by DR482.
5469  if (Cur->Equals(DC)) {
5470  if (Cur->isRecord()) {
5471  Diag(Loc, LangOpts.MicrosoftExt ? diag::warn_member_extra_qualification
5472  : diag::err_member_extra_qualification)
5473  << Name << FixItHint::CreateRemoval(SS.getRange());
5474  SS.clear();
5475  } else {
5476  Diag(Loc, diag::warn_namespace_member_extra_qualification) << Name;
5477  }
5478  return false;
5479  }
5480 
5481  // Check whether the qualifying scope encloses the scope of the original
5482  // declaration. For a template-id, we perform the checks in
5483  // CheckTemplateSpecializationScope.
5484  if (!Cur->Encloses(DC) && !IsTemplateId) {
5485  if (Cur->isRecord())
5486  Diag(Loc, diag::err_member_qualification)
5487  << Name << SS.getRange();
5488  else if (isa<TranslationUnitDecl>(DC))
5489  Diag(Loc, diag::err_invalid_declarator_global_scope)
5490  << Name << SS.getRange();
5491  else if (isa<FunctionDecl>(Cur))
5492  Diag(Loc, diag::err_invalid_declarator_in_function)
5493  << Name << SS.getRange();
5494  else if (isa<BlockDecl>(Cur))
5495  Diag(Loc, diag::err_invalid_declarator_in_block)
5496  << Name << SS.getRange();
5497  else
5498  Diag(Loc, diag::err_invalid_declarator_scope)
5499  << Name << cast<NamedDecl>(Cur) << cast<NamedDecl>(DC) << SS.getRange();
5500 
5501  return true;
5502  }
5503 
5504  if (Cur->isRecord()) {
5505  // Cannot qualify members within a class.
5506  Diag(Loc, diag::err_member_qualification)
5507  << Name << SS.getRange<