clang  14.0.0git
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/Expr.h"
25 #include "clang/AST/ExprCXX.h"
27 #include "clang/AST/StmtCXX.h"
28 #include "clang/Basic/Builtins.h"
31 #include "clang/Basic/TargetInfo.h"
32 #include "clang/Lex/HeaderSearch.h" // TODO: Sema shouldn't depend on Lex
33 #include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
34 #include "clang/Lex/ModuleLoader.h" // TODO: Sema shouldn't depend on Lex
35 #include "clang/Lex/Preprocessor.h" // Included for isCodeCompletionEnabled()
37 #include "clang/Sema/DeclSpec.h"
40 #include "clang/Sema/Lookup.h"
42 #include "clang/Sema/Scope.h"
43 #include "clang/Sema/ScopeInfo.h"
45 #include "clang/Sema/Template.h"
46 #include "llvm/ADT/SmallString.h"
47 #include "llvm/ADT/Triple.h"
48 #include <algorithm>
49 #include <cstring>
50 #include <functional>
51 #include <unordered_map>
52 
53 using namespace clang;
54 using namespace sema;
55 
57  if (OwnedType) {
58  Decl *Group[2] = { OwnedType, Ptr };
59  return DeclGroupPtrTy::make(DeclGroupRef::Create(Context, Group, 2));
60  }
61 
62  return DeclGroupPtrTy::make(DeclGroupRef(Ptr));
63 }
64 
65 namespace {
66 
67 class TypeNameValidatorCCC final : public CorrectionCandidateCallback {
68  public:
69  TypeNameValidatorCCC(bool AllowInvalid, bool WantClass = false,
70  bool AllowTemplates = false,
71  bool AllowNonTemplates = true)
72  : AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
73  AllowTemplates(AllowTemplates), AllowNonTemplates(AllowNonTemplates) {
74  WantExpressionKeywords = false;
75  WantCXXNamedCasts = false;
76  WantRemainingKeywords = false;
77  }
78 
79  bool ValidateCandidate(const TypoCorrection &candidate) override {
80  if (NamedDecl *ND = candidate.getCorrectionDecl()) {
81  if (!AllowInvalidDecl && ND->isInvalidDecl())
82  return false;
83 
84  if (getAsTypeTemplateDecl(ND))
85  return AllowTemplates;
86 
87  bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
88  if (!IsType)
89  return false;
90 
91  if (AllowNonTemplates)
92  return true;
93 
94  // An injected-class-name of a class template (specialization) is valid
95  // as a template or as a non-template.
96  if (AllowTemplates) {
97  auto *RD = dyn_cast<CXXRecordDecl>(ND);
98  if (!RD || !RD->isInjectedClassName())
99  return false;
100  RD = cast<CXXRecordDecl>(RD->getDeclContext());
101  return RD->getDescribedClassTemplate() ||
102  isa<ClassTemplateSpecializationDecl>(RD);
103  }
104 
105  return false;
106  }
107 
108  return !WantClassName && candidate.isKeyword();
109  }
110 
111  std::unique_ptr<CorrectionCandidateCallback> clone() override {
112  return std::make_unique<TypeNameValidatorCCC>(*this);
113  }
114 
115  private:
116  bool AllowInvalidDecl;
117  bool WantClassName;
118  bool AllowTemplates;
119  bool AllowNonTemplates;
120 };
121 
122 } // end anonymous namespace
123 
124 /// Determine whether the token kind starts a simple-type-specifier.
126  switch (Kind) {
127  // FIXME: Take into account the current language when deciding whether a
128  // token kind is a valid type specifier
129  case tok::kw_short:
130  case tok::kw_long:
131  case tok::kw___int64:
132  case tok::kw___int128:
133  case tok::kw_signed:
134  case tok::kw_unsigned:
135  case tok::kw_void:
136  case tok::kw_char:
137  case tok::kw_int:
138  case tok::kw_half:
139  case tok::kw_float:
140  case tok::kw_double:
141  case tok::kw___bf16:
142  case tok::kw__Float16:
143  case tok::kw___float128:
144  case tok::kw___ibm128:
145  case tok::kw_wchar_t:
146  case tok::kw_bool:
147  case tok::kw___underlying_type:
148  case tok::kw___auto_type:
149  return true;
150 
151  case tok::annot_typename:
152  case tok::kw_char16_t:
153  case tok::kw_char32_t:
154  case tok::kw_typeof:
155  case tok::annot_decltype:
156  case tok::kw_decltype:
157  return getLangOpts().CPlusPlus;
158 
159  case tok::kw_char8_t:
160  return getLangOpts().Char8;
161 
162  default:
163  break;
164  }
165 
166  return false;
167 }
168 
169 namespace {
170 enum class UnqualifiedTypeNameLookupResult {
171  NotFound,
172  FoundNonType,
173  FoundType
174 };
175 } // end anonymous namespace
176 
177 /// Tries to perform unqualified lookup of the type decls in bases for
178 /// dependent class.
179 /// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
180 /// type decl, \a FoundType if only type decls are found.
181 static UnqualifiedTypeNameLookupResult
183  SourceLocation NameLoc,
184  const CXXRecordDecl *RD) {
185  if (!RD->hasDefinition())
186  return UnqualifiedTypeNameLookupResult::NotFound;
187  // Look for type decls in base classes.
188  UnqualifiedTypeNameLookupResult FoundTypeDecl =
189  UnqualifiedTypeNameLookupResult::NotFound;
190  for (const auto &Base : RD->bases()) {
191  const CXXRecordDecl *BaseRD = nullptr;
192  if (auto *BaseTT = Base.getType()->getAs<TagType>())
193  BaseRD = BaseTT->getAsCXXRecordDecl();
194  else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
195  // Look for type decls in dependent base classes that have known primary
196  // templates.
197  if (!TST || !TST->isDependentType())
198  continue;
199  auto *TD = TST->getTemplateName().getAsTemplateDecl();
200  if (!TD)
201  continue;
202  if (auto *BasePrimaryTemplate =
203  dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
204  if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
205  BaseRD = BasePrimaryTemplate;
206  else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
208  CTD->findPartialSpecialization(Base.getType()))
209  if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
210  BaseRD = PS;
211  }
212  }
213  }
214  if (BaseRD) {
215  for (NamedDecl *ND : BaseRD->lookup(&II)) {
216  if (!isa<TypeDecl>(ND))
217  return UnqualifiedTypeNameLookupResult::FoundNonType;
218  FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
219  }
220  if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
221  switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
222  case UnqualifiedTypeNameLookupResult::FoundNonType:
223  return UnqualifiedTypeNameLookupResult::FoundNonType;
224  case UnqualifiedTypeNameLookupResult::FoundType:
225  FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
226  break;
227  case UnqualifiedTypeNameLookupResult::NotFound:
228  break;
229  }
230  }
231  }
232  }
233 
234  return FoundTypeDecl;
235 }
236 
238  const IdentifierInfo &II,
239  SourceLocation NameLoc) {
240  // Lookup in the parent class template context, if any.
241  const CXXRecordDecl *RD = nullptr;
242  UnqualifiedTypeNameLookupResult FoundTypeDecl =
243  UnqualifiedTypeNameLookupResult::NotFound;
244  for (DeclContext *DC = S.CurContext;
245  DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
246  DC = DC->getParent()) {
247  // Look for type decls in dependent base classes that have known primary
248  // templates.
249  RD = dyn_cast<CXXRecordDecl>(DC);
250  if (RD && RD->getDescribedClassTemplate())
251  FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
252  }
253  if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
254  return nullptr;
255 
256  // We found some types in dependent base classes. Recover as if the user
257  // wrote 'typename MyClass::II' instead of 'II'. We'll fully resolve the
258  // lookup during template instantiation.
259  S.Diag(NameLoc, diag::ext_found_in_dependent_base) << &II;
260 
261  ASTContext &Context = S.Context;
262  auto *NNS = NestedNameSpecifier::Create(Context, nullptr, false,
263  cast<Type>(Context.getRecordType(RD)));
264  QualType T = Context.getDependentNameType(ETK_Typename, NNS, &II);
265 
266  CXXScopeSpec SS;
267  SS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
268 
269  TypeLocBuilder Builder;
270  DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
271  DepTL.setNameLoc(NameLoc);
273  DepTL.setQualifierLoc(SS.getWithLocInContext(Context));
274  return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
275 }
276 
277 /// If the identifier refers to a type name within this scope,
278 /// return the declaration of that type.
279 ///
280 /// This routine performs ordinary name lookup of the identifier II
281 /// within the given scope, with optional C++ scope specifier SS, to
282 /// determine whether the name refers to a type. If so, returns an
283 /// opaque pointer (actually a QualType) corresponding to that
284 /// type. Otherwise, returns NULL.
286  Scope *S, CXXScopeSpec *SS,
287  bool isClassName, bool HasTrailingDot,
288  ParsedType ObjectTypePtr,
289  bool IsCtorOrDtorName,
290  bool WantNontrivialTypeSourceInfo,
291  bool IsClassTemplateDeductionContext,
292  IdentifierInfo **CorrectedII) {
293  // FIXME: Consider allowing this outside C++1z mode as an extension.
294  bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
295  getLangOpts().CPlusPlus17 && !IsCtorOrDtorName &&
296  !isClassName && !HasTrailingDot;
297 
298  // Determine where we will perform name lookup.
299  DeclContext *LookupCtx = nullptr;
300  if (ObjectTypePtr) {
301  QualType ObjectType = ObjectTypePtr.get();
302  if (ObjectType->isRecordType())
303  LookupCtx = computeDeclContext(ObjectType);
304  } else if (SS && SS->isNotEmpty()) {
305  LookupCtx = computeDeclContext(*SS, false);
306 
307  if (!LookupCtx) {
308  if (isDependentScopeSpecifier(*SS)) {
309  // C++ [temp.res]p3:
310  // A qualified-id that refers to a type and in which the
311  // nested-name-specifier depends on a template-parameter (14.6.2)
312  // shall be prefixed by the keyword typename to indicate that the
313  // qualified-id denotes a type, forming an
314  // elaborated-type-specifier (7.1.5.3).
315  //
316  // We therefore do not perform any name lookup if the result would
317  // refer to a member of an unknown specialization.
318  if (!isClassName && !IsCtorOrDtorName)
319  return nullptr;
320 
321  // We know from the grammar that this name refers to a type,
322  // so build a dependent node to describe the type.
323  if (WantNontrivialTypeSourceInfo)
324  return ActOnTypenameType(S, SourceLocation(), *SS, II, NameLoc).get();
325 
326  NestedNameSpecifierLoc QualifierLoc = SS->getWithLocInContext(Context);
327  QualType T = CheckTypenameType(ETK_None, SourceLocation(), QualifierLoc,
328  II, NameLoc);
329  return ParsedType::make(T);
330  }
331 
332  return nullptr;
333  }
334 
335  if (!LookupCtx->isDependentContext() &&
336  RequireCompleteDeclContext(*SS, LookupCtx))
337  return nullptr;
338  }
339 
340  // FIXME: LookupNestedNameSpecifierName isn't the right kind of
341  // lookup for class-names.
342  LookupNameKind Kind = isClassName ? LookupNestedNameSpecifierName :
343  LookupOrdinaryName;
344  LookupResult Result(*this, &II, NameLoc, Kind);
345  if (LookupCtx) {
346  // Perform "qualified" name lookup into the declaration context we
347  // computed, which is either the type of the base of a member access
348  // expression or the declaration context associated with a prior
349  // nested-name-specifier.
350  LookupQualifiedName(Result, LookupCtx);
351 
352  if (ObjectTypePtr && Result.empty()) {
353  // C++ [basic.lookup.classref]p3:
354  // If the unqualified-id is ~type-name, the type-name is looked up
355  // in the context of the entire postfix-expression. If the type T of
356  // the object expression is of a class type C, the type-name is also
357  // looked up in the scope of class C. At least one of the lookups shall
358  // find a name that refers to (possibly cv-qualified) T.
359  LookupName(Result, S);
360  }
361  } else {
362  // Perform unqualified name lookup.
363  LookupName(Result, S);
364 
365  // For unqualified lookup in a class template in MSVC mode, look into
366  // dependent base classes where the primary class template is known.
367  if (Result.empty() && getLangOpts().MSVCCompat && (!SS || SS->isEmpty())) {
368  if (ParsedType TypeInBase =
369  recoverFromTypeInKnownDependentBase(*this, II, NameLoc))
370  return TypeInBase;
371  }
372  }
373 
374  NamedDecl *IIDecl = nullptr;
375  switch (Result.getResultKind()) {
378  if (CorrectedII) {
379  TypeNameValidatorCCC CCC(/*AllowInvalid=*/true, isClassName,
380  AllowDeducedTemplate);
381  TypoCorrection Correction = CorrectTypo(Result.getLookupNameInfo(), Kind,
382  S, SS, CCC, CTK_ErrorRecovery);
383  IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
384  TemplateTy Template;
385  bool MemberOfUnknownSpecialization;
387  TemplateName.setIdentifier(NewII, NameLoc);
388  NestedNameSpecifier *NNS = Correction.getCorrectionSpecifier();
389  CXXScopeSpec NewSS, *NewSSPtr = SS;
390  if (SS && NNS) {
391  NewSS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
392  NewSSPtr = &NewSS;
393  }
394  if (Correction && (NNS || NewII != &II) &&
395  // Ignore a correction to a template type as the to-be-corrected
396  // identifier is not a template (typo correction for template names
397  // is handled elsewhere).
398  !(getLangOpts().CPlusPlus && NewSSPtr &&
399  isTemplateName(S, *NewSSPtr, false, TemplateName, nullptr, false,
400  Template, MemberOfUnknownSpecialization))) {
401  ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
402  isClassName, HasTrailingDot, ObjectTypePtr,
403  IsCtorOrDtorName,
404  WantNontrivialTypeSourceInfo,
405  IsClassTemplateDeductionContext);
406  if (Ty) {
407  diagnoseTypo(Correction,
408  PDiag(diag::err_unknown_type_or_class_name_suggest)
409  << Result.getLookupName() << isClassName);
410  if (SS && NNS)
411  SS->MakeTrivial(Context, NNS, SourceRange(NameLoc));
412  *CorrectedII = NewII;
413  return Ty;
414  }
415  }
416  }
417  // If typo correction failed or was not performed, fall through
418  LLVM_FALLTHROUGH;
421  Result.suppressDiagnostics();
422  return nullptr;
423 
425  // Recover from type-hiding ambiguities by hiding the type. We'll
426  // do the lookup again when looking for an object, and we can
427  // diagnose the error then. If we don't do this, then the error
428  // about hiding the type will be immediately followed by an error
429  // that only makes sense if the identifier was treated like a type.
430  if (Result.getAmbiguityKind() == LookupResult::AmbiguousTagHiding) {
431  Result.suppressDiagnostics();
432  return nullptr;
433  }
434 
435  // Look to see if we have a type anywhere in the list of results.
436  for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
437  Res != ResEnd; ++Res) {
438  NamedDecl *RealRes = (*Res)->getUnderlyingDecl();
439  if (isa<TypeDecl, ObjCInterfaceDecl, UnresolvedUsingIfExistsDecl>(
440  RealRes) ||
441  (AllowDeducedTemplate && getAsTypeTemplateDecl(RealRes))) {
442  if (!IIDecl ||
443  // Make the selection of the recovery decl deterministic.
444  RealRes->getLocation() < IIDecl->getLocation())
445  IIDecl = RealRes;
446  }
447  }
448 
449  if (!IIDecl) {
450  // None of the entities we found is a type, so there is no way
451  // to even assume that the result is a type. In this case, don't
452  // complain about the ambiguity. The parser will either try to
453  // perform this lookup again (e.g., as an object name), which
454  // will produce the ambiguity, or will complain that it expected
455  // a type name.
456  Result.suppressDiagnostics();
457  return nullptr;
458  }
459 
460  // We found a type within the ambiguous lookup; diagnose the
461  // ambiguity and then return that type. This might be the right
462  // answer, or it might not be, but it suppresses any attempt to
463  // perform the name lookup again.
464  break;
465 
466  case LookupResult::Found:
467  IIDecl = Result.getFoundDecl();
468  break;
469  }
470 
471  assert(IIDecl && "Didn't find decl");
472 
473  QualType T;
474  if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
475  // C++ [class.qual]p2: A lookup that would find the injected-class-name
476  // instead names the constructors of the class, except when naming a class.
477  // This is ill-formed when we're not actually forming a ctor or dtor name.
478  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
479  auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
480  if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
481  FoundRD->isInjectedClassName() &&
482  declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
483  Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
484  << &II << /*Type*/1;
485 
486  DiagnoseUseOfDecl(IIDecl, NameLoc);
487 
488  T = Context.getTypeDeclType(TD);
489  MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
490  } else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
491  (void)DiagnoseUseOfDecl(IDecl, NameLoc);
492  if (!HasTrailingDot)
493  T = Context.getObjCInterfaceType(IDecl);
494  } else if (auto *UD = dyn_cast<UnresolvedUsingIfExistsDecl>(IIDecl)) {
495  (void)DiagnoseUseOfDecl(UD, NameLoc);
496  // Recover with 'int'
497  T = Context.IntTy;
498  } else if (AllowDeducedTemplate) {
499  if (auto *TD = getAsTypeTemplateDecl(IIDecl))
501  QualType(), false);
502  }
503 
504  if (T.isNull()) {
505  // If it's not plausibly a type, suppress diagnostics.
506  Result.suppressDiagnostics();
507  return nullptr;
508  }
509 
510  // NOTE: avoid constructing an ElaboratedType(Loc) if this is a
511  // constructor or destructor name (in such a case, the scope specifier
512  // will be attached to the enclosing Expr or Decl node).
513  if (SS && SS->isNotEmpty() && !IsCtorOrDtorName &&
514  !isa<ObjCInterfaceDecl, UnresolvedUsingIfExistsDecl>(IIDecl)) {
515  if (WantNontrivialTypeSourceInfo) {
516  // Construct a type with type-source information.
517  TypeLocBuilder Builder;
518  Builder.pushTypeSpec(T).setNameLoc(NameLoc);
519 
520  T = getElaboratedType(ETK_None, *SS, T);
521  ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
523  ElabTL.setQualifierLoc(SS->getWithLocInContext(Context));
524  return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
525  } else {
526  T = getElaboratedType(ETK_None, *SS, T);
527  }
528  }
529 
530  return ParsedType::make(T);
531 }
532 
533 // Builds a fake NNS for the given decl context.
534 static NestedNameSpecifier *
536  for (;; DC = DC->getLookupParent()) {
537  DC = DC->getPrimaryContext();
538  auto *ND = dyn_cast<NamespaceDecl>(DC);
539  if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
540  return NestedNameSpecifier::Create(Context, nullptr, ND);
541  else if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
542  return NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
543  RD->getTypeForDecl());
544  else if (isa<TranslationUnitDecl>(DC))
545  return NestedNameSpecifier::GlobalSpecifier(Context);
546  }
547  llvm_unreachable("something isn't in TU scope?");
548 }
549 
550 /// Find the parent class with dependent bases of the innermost enclosing method
551 /// context. Do not look for enclosing CXXRecordDecls directly, or we will end
552 /// up allowing unqualified dependent type names at class-level, which MSVC
553 /// correctly rejects.
554 static const CXXRecordDecl *
556  for (; DC && DC->isDependentContext(); DC = DC->getLookupParent()) {
557  DC = DC->getPrimaryContext();
558  if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
559  if (MD->getParent()->hasAnyDependentBases())
560  return MD->getParent();
561  }
562  return nullptr;
563 }
564 
566  SourceLocation NameLoc,
567  bool IsTemplateTypeArg) {
568  assert(getLangOpts().MSVCCompat && "shouldn't be called in non-MSVC mode");
569 
570  NestedNameSpecifier *NNS = nullptr;
571  if (IsTemplateTypeArg && getCurScope()->isTemplateParamScope()) {
572  // If we weren't able to parse a default template argument, delay lookup
573  // until instantiation time by making a non-dependent DependentTypeName. We
574  // pretend we saw a NestedNameSpecifier referring to the current scope, and
575  // lookup is retried.
576  // FIXME: This hurts our diagnostic quality, since we get errors like "no
577  // type named 'Foo' in 'current_namespace'" when the user didn't write any
578  // name specifiers.
579  NNS = synthesizeCurrentNestedNameSpecifier(Context, CurContext);
580  Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
581  } else if (const CXXRecordDecl *RD =
583  // Build a DependentNameType that will perform lookup into RD at
584  // instantiation time.
585  NNS = NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
586  RD->getTypeForDecl());
587 
588  // Diagnose that this identifier was undeclared, and retry the lookup during
589  // template instantiation.
590  Diag(NameLoc, diag::ext_undeclared_unqual_id_with_dependent_base) << &II
591  << RD;
592  } else {
593  // This is not a situation that we should recover from.
594  return ParsedType();
595  }
596 
597  QualType T = Context.getDependentNameType(ETK_None, NNS, &II);
598 
599  // Build type location information. We synthesized the qualifier, so we have
600  // to build a fake NestedNameSpecifierLoc.
601  NestedNameSpecifierLocBuilder NNSLocBuilder;
602  NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
603  NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);
604 
605  TypeLocBuilder Builder;
606  DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
607  DepTL.setNameLoc(NameLoc);
609  DepTL.setQualifierLoc(QualifierLoc);
610  return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
611 }
612 
613 /// isTagName() - This method is called *for error recovery purposes only*
614 /// to determine if the specified name is a valid tag name ("struct foo"). If
615 /// so, this returns the TST for the tag corresponding to it (TST_enum,
616 /// TST_union, TST_struct, TST_interface, TST_class). This is used to diagnose
617 /// cases in C where the user forgot to specify the tag.
619  // Do a tag name lookup in this scope.
620  LookupResult R(*this, &II, SourceLocation(), LookupTagName);
621  LookupName(R, S, false);
624  if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
625  switch (TD->getTagKind()) {
626  case TTK_Struct: return DeclSpec::TST_struct;
628  case TTK_Union: return DeclSpec::TST_union;
629  case TTK_Class: return DeclSpec::TST_class;
630  case TTK_Enum: return DeclSpec::TST_enum;
631  }
632  }
633 
635 }
636 
637 /// isMicrosoftMissingTypename - In Microsoft mode, within class scope,
638 /// if a CXXScopeSpec's type is equal to the type of one of the base classes
639 /// then downgrade the missing typename error to a warning.
640 /// This is needed for MSVC compatibility; Example:
641 /// @code
642 /// template<class T> class A {
643 /// public:
644 /// typedef int TYPE;
645 /// };
646 /// template<class T> class B : public A<T> {
647 /// public:
648 /// A<T>::TYPE a; // no typename required because A<T> is a base class.
649 /// };
650 /// @endcode
652  if (CurContext->isRecord()) {
654  return true;
655 
656  const Type *Ty = SS->getScopeRep()->getAsType();
657 
658  CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
659  for (const auto &Base : RD->bases())
660  if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
661  return true;
662  return S->isFunctionPrototypeScope();
663  }
664  return CurContext->isFunctionOrMethod() || S->isFunctionPrototypeScope();
665 }
666 
668  SourceLocation IILoc,
669  Scope *S,
670  CXXScopeSpec *SS,
671  ParsedType &SuggestedType,
672  bool IsTemplateName) {
673  // Don't report typename errors for editor placeholders.
674  if (II->isEditorPlaceholder())
675  return;
676  // We don't have anything to suggest (yet).
677  SuggestedType = nullptr;
678 
679  // There may have been a typo in the name of the type. Look up typo
680  // results, in case we have something that we can suggest.
681  TypeNameValidatorCCC CCC(/*AllowInvalid=*/false, /*WantClass=*/false,
682  /*AllowTemplates=*/IsTemplateName,
683  /*AllowNonTemplates=*/!IsTemplateName);
684  if (TypoCorrection Corrected =
685  CorrectTypo(DeclarationNameInfo(II, IILoc), LookupOrdinaryName, S, SS,
686  CCC, CTK_ErrorRecovery)) {
687  // FIXME: Support error recovery for the template-name case.
688  bool CanRecover = !IsTemplateName;
689  if (Corrected.isKeyword()) {
690  // We corrected to a keyword.
691  diagnoseTypo(Corrected,
692  PDiag(IsTemplateName ? diag::err_no_template_suggest
693  : diag::err_unknown_typename_suggest)
694  << II);
695  II = Corrected.getCorrectionAsIdentifierInfo();
696  } else {
697  // We found a similarly-named type or interface; suggest that.
698  if (!SS || !SS->isSet()) {
699  diagnoseTypo(Corrected,
700  PDiag(IsTemplateName ? diag::err_no_template_suggest
701  : diag::err_unknown_typename_suggest)
702  << II, CanRecover);
703  } else if (DeclContext *DC = computeDeclContext(*SS, false)) {
704  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
705  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
706  II->getName().equals(CorrectedStr);
707  diagnoseTypo(Corrected,
708  PDiag(IsTemplateName
709  ? diag::err_no_member_template_suggest
710  : diag::err_unknown_nested_typename_suggest)
711  << II << DC << DroppedSpecifier << SS->getRange(),
712  CanRecover);
713  } else {
714  llvm_unreachable("could not have corrected a typo here");
715  }
716 
717  if (!CanRecover)
718  return;
719 
720  CXXScopeSpec tmpSS;
721  if (Corrected.getCorrectionSpecifier())
722  tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
723  SourceRange(IILoc));
724  // FIXME: Support class template argument deduction here.
725  SuggestedType =
726  getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
727  tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
728  /*IsCtorOrDtorName=*/false,
729  /*WantNontrivialTypeSourceInfo=*/true);
730  }
731  return;
732  }
733 
734  if (getLangOpts().CPlusPlus && !IsTemplateName) {
735  // See if II is a class template that the user forgot to pass arguments to.
736  UnqualifiedId Name;
737  Name.setIdentifier(II, IILoc);
738  CXXScopeSpec EmptySS;
739  TemplateTy TemplateResult;
740  bool MemberOfUnknownSpecialization;
741  if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
742  Name, nullptr, true, TemplateResult,
743  MemberOfUnknownSpecialization) == TNK_Type_template) {
744  diagnoseMissingTemplateArguments(TemplateResult.get(), IILoc);
745  return;
746  }
747  }
748 
749  // FIXME: Should we move the logic that tries to recover from a missing tag
750  // (struct, union, enum) from Parser::ParseImplicitInt here, instead?
751 
752  if (!SS || (!SS->isSet() && !SS->isInvalid()))
753  Diag(IILoc, IsTemplateName ? diag::err_no_template
754  : diag::err_unknown_typename)
755  << II;
756  else if (DeclContext *DC = computeDeclContext(*SS, false))
757  Diag(IILoc, IsTemplateName ? diag::err_no_member_template
758  : diag::err_typename_nested_not_found)
759  << II << DC << SS->getRange();
760  else if (SS->isValid() && SS->getScopeRep()->containsErrors()) {
761  SuggestedType =
762  ActOnTypenameType(S, SourceLocation(), *SS, *II, IILoc).get();
763  } else if (isDependentScopeSpecifier(*SS)) {
764  unsigned DiagID = diag::err_typename_missing;
765  if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
766  DiagID = diag::ext_typename_missing;
767 
768  Diag(SS->getRange().getBegin(), DiagID)
769  << SS->getScopeRep() << II->getName()
770  << SourceRange(SS->getRange().getBegin(), IILoc)
771  << FixItHint::CreateInsertion(SS->getRange().getBegin(), "typename ");
772  SuggestedType = ActOnTypenameType(S, SourceLocation(),
773  *SS, *II, IILoc).get();
774  } else {
775  assert(SS && SS->isInvalid() &&
776  "Invalid scope specifier has already been diagnosed");
777  }
778 }
779 
780 /// Determine whether the given result set contains either a type name
781 /// or
782 static bool isResultTypeOrTemplate(LookupResult &R, const Token &NextToken) {
783  bool CheckTemplate = R.getSema().getLangOpts().CPlusPlus &&
784  NextToken.is(tok::less);
785 
786  for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
787  if (isa<TypeDecl>(*I) || isa<ObjCInterfaceDecl>(*I))
788  return true;
789 
790  if (CheckTemplate && isa<TemplateDecl>(*I))
791  return true;
792  }
793 
794  return false;
795 }
796 
797 static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
798  Scope *S, CXXScopeSpec &SS,
799  IdentifierInfo *&Name,
800  SourceLocation NameLoc) {
801  LookupResult R(SemaRef, Name, NameLoc, Sema::LookupTagName);
802  SemaRef.LookupParsedName(R, S, &SS);
803  if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
804  StringRef FixItTagName;
805  switch (Tag->getTagKind()) {
806  case TTK_Class:
807  FixItTagName = "class ";
808  break;
809 
810  case TTK_Enum:
811  FixItTagName = "enum ";
812  break;
813 
814  case TTK_Struct:
815  FixItTagName = "struct ";
816  break;
817 
818  case TTK_Interface:
819  FixItTagName = "__interface ";
820  break;
821 
822  case TTK_Union:
823  FixItTagName = "union ";
824  break;
825  }
826 
827  StringRef TagName = FixItTagName.drop_back();
828  SemaRef.Diag(NameLoc, diag::err_use_of_tag_name_without_tag)
829  << Name << TagName << SemaRef.getLangOpts().CPlusPlus
830  << FixItHint::CreateInsertion(NameLoc, FixItTagName);
831 
832  for (LookupResult::iterator I = Result.begin(), IEnd = Result.end();
833  I != IEnd; ++I)
834  SemaRef.Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
835  << Name << TagName;
836 
837  // Replace lookup results with just the tag decl.
838  Result.clear(Sema::LookupTagName);
839  SemaRef.LookupParsedName(Result, S, &SS);
840  return true;
841  }
842 
843  return false;
844 }
845 
846 /// Build a ParsedType for a simple-type-specifier with a nested-name-specifier.
848  QualType T, SourceLocation NameLoc) {
849  ASTContext &Context = S.Context;
850 
851  TypeLocBuilder Builder;
852  Builder.pushTypeSpec(T).setNameLoc(NameLoc);
853 
854  T = S.getElaboratedType(ETK_None, SS, T);
855  ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
857  ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
858  return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
859 }
860 
862  IdentifierInfo *&Name,
863  SourceLocation NameLoc,
864  const Token &NextToken,
866  DeclarationNameInfo NameInfo(Name, NameLoc);
867  ObjCMethodDecl *CurMethod = getCurMethodDecl();
868 
869  assert(NextToken.isNot(tok::coloncolon) &&
870  "parse nested name specifiers before calling ClassifyName");
871  if (getLangOpts().CPlusPlus && SS.isSet() &&
872  isCurrentClassName(*Name, S, &SS)) {
873  // Per [class.qual]p2, this names the constructors of SS, not the
874  // injected-class-name. We don't have a classification for that.
875  // There's not much point caching this result, since the parser
876  // will reject it later.
878  }
879 
880  LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
881  LookupParsedName(Result, S, &SS, !CurMethod);
882 
883  if (SS.isInvalid())
884  return NameClassification::Error();
885 
886  // For unqualified lookup in a class template in MSVC mode, look into
887  // dependent base classes where the primary class template is known.
888  if (Result.empty() && SS.isEmpty() && getLangOpts().MSVCCompat) {
889  if (ParsedType TypeInBase =
890  recoverFromTypeInKnownDependentBase(*this, *Name, NameLoc))
891  return TypeInBase;
892  }
893 
894  // Perform lookup for Objective-C instance variables (including automatically
895  // synthesized instance variables), if we're in an Objective-C method.
896  // FIXME: This lookup really, really needs to be folded in to the normal
897  // unqualified lookup mechanism.
898  if (SS.isEmpty() && CurMethod && !isResultTypeOrTemplate(Result, NextToken)) {
899  DeclResult Ivar = LookupIvarInObjCMethod(Result, S, Name);
900  if (Ivar.isInvalid())
901  return NameClassification::Error();
902  if (Ivar.isUsable())
903  return NameClassification::NonType(cast<NamedDecl>(Ivar.get()));
904 
905  // We defer builtin creation until after ivar lookup inside ObjC methods.
906  if (Result.empty())
907  LookupBuiltin(Result);
908  }
909 
910  bool SecondTry = false;
911  bool IsFilteredTemplateName = false;
912 
913 Corrected:
914  switch (Result.getResultKind()) {
916  // If an unqualified-id is followed by a '(', then we have a function
917  // call.
918  if (SS.isEmpty() && NextToken.is(tok::l_paren)) {
919  // In C++, this is an ADL-only call.
920  // FIXME: Reference?
921  if (getLangOpts().CPlusPlus)
922  return NameClassification::UndeclaredNonType();
923 
924  // C90 6.3.2.2:
925  // If the expression that precedes the parenthesized argument list in a
926  // function call consists solely of an identifier, and if no
927  // declaration is visible for this identifier, the identifier is
928  // implicitly declared exactly as if, in the innermost block containing
929  // the function call, the declaration
930  //
931  // extern int identifier ();
932  //
933  // appeared.
934  //
935  // We also allow this in C99 as an extension.
936  if (NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *Name, S))
937  return NameClassification::NonType(D);
938  }
939 
940  if (getLangOpts().CPlusPlus20 && SS.isEmpty() && NextToken.is(tok::less)) {
941  // In C++20 onwards, this could be an ADL-only call to a function
942  // template, and we're required to assume that this is a template name.
943  //
944  // FIXME: Find a way to still do typo correction in this case.
945  TemplateName Template =
946  Context.getAssumedTemplateName(NameInfo.getName());
947  return NameClassification::UndeclaredTemplate(Template);
948  }
949 
950  // In C, we first see whether there is a tag type by the same name, in
951  // which case it's likely that the user just forgot to write "enum",
952  // "struct", or "union".
953  if (!getLangOpts().CPlusPlus && !SecondTry &&
954  isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
955  break;
956  }
957 
958  // Perform typo correction to determine if there is another name that is
959  // close to this name.
960  if (!SecondTry && CCC) {
961  SecondTry = true;
962  if (TypoCorrection Corrected =
963  CorrectTypo(Result.getLookupNameInfo(), Result.getLookupKind(), S,
964  &SS, *CCC, CTK_ErrorRecovery)) {
965  unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
966  unsigned QualifiedDiag = diag::err_no_member_suggest;
967 
968  NamedDecl *FirstDecl = Corrected.getFoundDecl();
969  NamedDecl *UnderlyingFirstDecl = Corrected.getCorrectionDecl();
970  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
971  UnderlyingFirstDecl && isa<TemplateDecl>(UnderlyingFirstDecl)) {
972  UnqualifiedDiag = diag::err_no_template_suggest;
973  QualifiedDiag = diag::err_no_member_template_suggest;
974  } else if (UnderlyingFirstDecl &&
975  (isa<TypeDecl>(UnderlyingFirstDecl) ||
976  isa<ObjCInterfaceDecl>(UnderlyingFirstDecl) ||
977  isa<ObjCCompatibleAliasDecl>(UnderlyingFirstDecl))) {
978  UnqualifiedDiag = diag::err_unknown_typename_suggest;
979  QualifiedDiag = diag::err_unknown_nested_typename_suggest;
980  }
981 
982  if (SS.isEmpty()) {
983  diagnoseTypo(Corrected, PDiag(UnqualifiedDiag) << Name);
984  } else {// FIXME: is this even reachable? Test it.
985  std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
986  bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
987  Name->getName().equals(CorrectedStr);
988  diagnoseTypo(Corrected, PDiag(QualifiedDiag)
989  << Name << computeDeclContext(SS, false)
990  << DroppedSpecifier << SS.getRange());
991  }
992 
993  // Update the name, so that the caller has the new name.
994  Name = Corrected.getCorrectionAsIdentifierInfo();
995 
996  // Typo correction corrected to a keyword.
997  if (Corrected.isKeyword())
998  return Name;
999 
1000  // Also update the LookupResult...
1001  // FIXME: This should probably go away at some point
1002  Result.clear();
1003  Result.setLookupName(Corrected.getCorrection());
1004  if (FirstDecl)
1005  Result.addDecl(FirstDecl);
1006 
1007  // If we found an Objective-C instance variable, let
1008  // LookupInObjCMethod build the appropriate expression to
1009  // reference the ivar.
1010  // FIXME: This is a gross hack.
1011  if (ObjCIvarDecl *Ivar = Result.getAsSingle<ObjCIvarDecl>()) {
1012  DeclResult R =
1013  LookupIvarInObjCMethod(Result, S, Ivar->getIdentifier());
1014  if (R.isInvalid())
1015  return NameClassification::Error();
1016  if (R.isUsable())
1017  return NameClassification::NonType(Ivar);
1018  }
1019 
1020  goto Corrected;
1021  }
1022  }
1023 
1024  // We failed to correct; just fall through and let the parser deal with it.
1025  Result.suppressDiagnostics();
1026  return NameClassification::Unknown();
1027 
1029  // We performed name lookup into the current instantiation, and there were
1030  // dependent bases, so we treat this result the same way as any other
1031  // dependent nested-name-specifier.
1032 
1033  // C++ [temp.res]p2:
1034  // A name used in a template declaration or definition and that is
1035  // dependent on a template-parameter is assumed not to name a type
1036  // unless the applicable name lookup finds a type name or the name is
1037  // qualified by the keyword typename.
1038  //
1039  // FIXME: If the next token is '<', we might want to ask the parser to
1040  // perform some heroics to see if we actually have a
1041  // template-argument-list, which would indicate a missing 'template'
1042  // keyword here.
1043  return NameClassification::DependentNonType();
1044  }
1045 
1046  case LookupResult::Found:
1049  break;
1050 
1052  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
1053  hasAnyAcceptableTemplateNames(Result, /*AllowFunctionTemplates=*/true,
1054  /*AllowDependent=*/false)) {
1055  // C++ [temp.local]p3:
1056  // A lookup that finds an injected-class-name (10.2) can result in an
1057  // ambiguity in certain cases (for example, if it is found in more than
1058  // one base class). If all of the injected-class-names that are found
1059  // refer to specializations of the same class template, and if the name
1060  // is followed by a template-argument-list, the reference refers to the
1061  // class template itself and not a specialization thereof, and is not
1062  // ambiguous.
1063  //
1064  // This filtering can make an ambiguous result into an unambiguous one,
1065  // so try again after filtering out template names.
1066  FilterAcceptableTemplateNames(Result);
1067  if (!Result.isAmbiguous()) {
1068  IsFilteredTemplateName = true;
1069  break;
1070  }
1071  }
1072 
1073  // Diagnose the ambiguity and return an error.
1074  return NameClassification::Error();
1075  }
1076 
1077  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
1078  (IsFilteredTemplateName ||
1079  hasAnyAcceptableTemplateNames(
1080  Result, /*AllowFunctionTemplates=*/true,
1081  /*AllowDependent=*/false,
1082  /*AllowNonTemplateFunctions*/ SS.isEmpty() &&
1083  getLangOpts().CPlusPlus20))) {
1084  // C++ [temp.names]p3:
1085  // After name lookup (3.4) finds that a name is a template-name or that
1086  // an operator-function-id or a literal- operator-id refers to a set of
1087  // overloaded functions any member of which is a function template if
1088  // this is followed by a <, the < is always taken as the delimiter of a
1089  // template-argument-list and never as the less-than operator.
1090  // C++2a [temp.names]p2:
1091  // A name is also considered to refer to a template if it is an
1092  // unqualified-id followed by a < and name lookup finds either one
1093  // or more functions or finds nothing.
1094  if (!IsFilteredTemplateName)
1095  FilterAcceptableTemplateNames(Result);
1096 
1097  bool IsFunctionTemplate;
1098  bool IsVarTemplate;
1099  TemplateName Template;
1100  if (Result.end() - Result.begin() > 1) {
1101  IsFunctionTemplate = true;
1102  Template = Context.getOverloadedTemplateName(Result.begin(),
1103  Result.end());
1104  } else if (!Result.empty()) {
1105  auto *TD = cast<TemplateDecl>(getAsTemplateNameDecl(
1106  *Result.begin(), /*AllowFunctionTemplates=*/true,
1107  /*AllowDependent=*/false));
1108  IsFunctionTemplate = isa<FunctionTemplateDecl>(TD);
1109  IsVarTemplate = isa<VarTemplateDecl>(TD);
1110 
1111  if (SS.isNotEmpty())
1112  Template =
1114  /*TemplateKeyword=*/false, TD);
1115  else
1116  Template = TemplateName(TD);
1117  } else {
1118  // All results were non-template functions. This is a function template
1119  // name.
1120  IsFunctionTemplate = true;
1121  Template = Context.getAssumedTemplateName(NameInfo.getName());
1122  }
1123 
1124  if (IsFunctionTemplate) {
1125  // Function templates always go through overload resolution, at which
1126  // point we'll perform the various checks (e.g., accessibility) we need
1127  // to based on which function we selected.
1128  Result.suppressDiagnostics();
1129 
1130  return NameClassification::FunctionTemplate(Template);
1131  }
1132 
1133  return IsVarTemplate ? NameClassification::VarTemplate(Template)
1134  : NameClassification::TypeTemplate(Template);
1135  }
1136 
1137  NamedDecl *FirstDecl = (*Result.begin())->getUnderlyingDecl();
1138  if (TypeDecl *Type = dyn_cast<TypeDecl>(FirstDecl)) {
1139  DiagnoseUseOfDecl(Type, NameLoc);
1140  MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
1141  QualType T = Context.getTypeDeclType(Type);
1142  if (SS.isNotEmpty())
1143  return buildNestedType(*this, SS, T, NameLoc);
1144  return ParsedType::make(T);
1145  }
1146 
1147  ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(FirstDecl);
1148  if (!Class) {
1149  // FIXME: It's unfortunate that we don't have a Type node for handling this.
1150  if (ObjCCompatibleAliasDecl *Alias =
1151  dyn_cast<ObjCCompatibleAliasDecl>(FirstDecl))
1152  Class = Alias->getClassInterface();
1153  }
1154 
1155  if (Class) {
1156  DiagnoseUseOfDecl(Class, NameLoc);
1157 
1158  if (NextToken.is(tok::period)) {
1159  // Interface. <something> is parsed as a property reference expression.
1160  // Just return "unknown" as a fall-through for now.
1161  Result.suppressDiagnostics();
1162  return NameClassification::Unknown();
1163  }
1164 
1165  QualType T = Context.getObjCInterfaceType(Class);
1166  return ParsedType::make(T);
1167  }
1168 
1169  if (isa<ConceptDecl>(FirstDecl))
1170  return NameClassification::Concept(
1171  TemplateName(cast<TemplateDecl>(FirstDecl)));
1172 
1173  if (auto *EmptyD = dyn_cast<UnresolvedUsingIfExistsDecl>(FirstDecl)) {
1174  (void)DiagnoseUseOfDecl(EmptyD, NameLoc);
1175  return NameClassification::Error();
1176  }
1177 
1178  // We can have a type template here if we're classifying a template argument.
1179  if (isa<TemplateDecl>(FirstDecl) && !isa<FunctionTemplateDecl>(FirstDecl) &&
1180  !isa<VarTemplateDecl>(FirstDecl))
1181  return NameClassification::TypeTemplate(
1182  TemplateName(cast<TemplateDecl>(FirstDecl)));
1183 
1184  // Check for a tag type hidden by a non-type decl in a few cases where it
1185  // seems likely a type is wanted instead of the non-type that was found.
1186  bool NextIsOp = NextToken.isOneOf(tok::amp, tok::star);
1187  if ((NextToken.is(tok::identifier) ||
1188  (NextIsOp &&
1189  FirstDecl->getUnderlyingDecl()->isFunctionOrFunctionTemplate())) &&
1190  isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
1191  TypeDecl *Type = Result.getAsSingle<TypeDecl>();
1192  DiagnoseUseOfDecl(Type, NameLoc);
1193  QualType T = Context.getTypeDeclType(Type);
1194  if (SS.isNotEmpty())
1195  return buildNestedType(*this, SS, T, NameLoc);
1196  return ParsedType::make(T);
1197  }
1198 
1199  // If we already know which single declaration is referenced, just annotate
1200  // that declaration directly. Defer resolving even non-overloaded class
1201  // member accesses, as we need to defer certain access checks until we know
1202  // the context.
1203  bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
1204  if (Result.isSingleResult() && !ADL && !FirstDecl->isCXXClassMember())
1205  return NameClassification::NonType(Result.getRepresentativeDecl());
1206 
1207  // Otherwise, this is an overload set that we will need to resolve later.
1208  Result.suppressDiagnostics();
1209  return NameClassification::OverloadSet(UnresolvedLookupExpr::Create(
1210  Context, Result.getNamingClass(), SS.getWithLocInContext(Context),
1211  Result.getLookupNameInfo(), ADL, Result.isOverloadedResult(),
1212  Result.begin(), Result.end()));
1213 }
1214 
1215 ExprResult
1217  SourceLocation NameLoc) {
1218  assert(getLangOpts().CPlusPlus && "ADL-only call in C?");
1219  CXXScopeSpec SS;
1220  LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
1221  return BuildDeclarationNameExpr(SS, Result, /*ADL=*/true);
1222 }
1223 
1224 ExprResult
1226  IdentifierInfo *Name,
1227  SourceLocation NameLoc,
1228  bool IsAddressOfOperand) {
1229  DeclarationNameInfo NameInfo(Name, NameLoc);
1230  return ActOnDependentIdExpression(SS, /*TemplateKWLoc=*/SourceLocation(),
1231  NameInfo, IsAddressOfOperand,
1232  /*TemplateArgs=*/nullptr);
1233 }
1234 
1236  NamedDecl *Found,
1237  SourceLocation NameLoc,
1238  const Token &NextToken) {
1239  if (getCurMethodDecl() && SS.isEmpty())
1240  if (auto *Ivar = dyn_cast<ObjCIvarDecl>(Found->getUnderlyingDecl()))
1241  return BuildIvarRefExpr(S, NameLoc, Ivar);
1242 
1243  // Reconstruct the lookup result.
1244  LookupResult Result(*this, Found->getDeclName(), NameLoc, LookupOrdinaryName);
1245  Result.addDecl(Found);
1246  Result.resolveKind();
1247 
1248  bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
1249  return BuildDeclarationNameExpr(SS, Result, ADL);
1250 }
1251 
1253  // For an implicit class member access, transform the result into a member
1254  // access expression if necessary.
1255  auto *ULE = cast<UnresolvedLookupExpr>(E);
1256  if ((*ULE->decls_begin())->isCXXClassMember()) {
1257  CXXScopeSpec SS;
1258  SS.Adopt(ULE->getQualifierLoc());
1259 
1260  // Reconstruct the lookup result.
1261  LookupResult Result(*this, ULE->getName(), ULE->getNameLoc(),
1262  LookupOrdinaryName);
1263  Result.setNamingClass(ULE->getNamingClass());
1264  for (auto I = ULE->decls_begin(), E = ULE->decls_end(); I != E; ++I)
1265  Result.addDecl(*I, I.getAccess());
1266  Result.resolveKind();
1267  return BuildPossibleImplicitMemberExpr(SS, SourceLocation(), Result,
1268  nullptr, S);
1269  }
1270 
1271  // Otherwise, this is already in the form we needed, and no further checks
1272  // are necessary.
1273  return ULE;
1274 }
1275 
1278  auto *TD = Name.getAsTemplateDecl();
1279  if (!TD)
1280  return TemplateNameKindForDiagnostics::DependentTemplate;
1281  if (isa<ClassTemplateDecl>(TD))
1282  return TemplateNameKindForDiagnostics::ClassTemplate;
1283  if (isa<FunctionTemplateDecl>(TD))
1284  return TemplateNameKindForDiagnostics::FunctionTemplate;
1285  if (isa<VarTemplateDecl>(TD))
1286  return TemplateNameKindForDiagnostics::VarTemplate;
1287  if (isa<TypeAliasTemplateDecl>(TD))
1288  return TemplateNameKindForDiagnostics::AliasTemplate;
1289  if (isa<TemplateTemplateParmDecl>(TD))
1290  return TemplateNameKindForDiagnostics::TemplateTemplateParam;
1291  if (isa<ConceptDecl>(TD))
1292  return TemplateNameKindForDiagnostics::Concept;
1293  return TemplateNameKindForDiagnostics::DependentTemplate;
1294 }
1295 
1297  assert(DC->getLexicalParent() == CurContext &&
1298  "The next DeclContext should be lexically contained in the current one.");
1299  CurContext = DC;
1300  S->setEntity(DC);
1301 }
1302 
1304  assert(CurContext && "DeclContext imbalance!");
1305 
1306  CurContext = CurContext->getLexicalParent();
1307  assert(CurContext && "Popped translation unit!");
1308 }
1309 
1311  Decl *D) {
1312  // Unlike PushDeclContext, the context to which we return is not necessarily
1313  // the containing DC of TD, because the new context will be some pre-existing
1314  // TagDecl definition instead of a fresh one.
1315  auto Result = static_cast<SkippedDefinitionContext>(CurContext);
1316  CurContext = cast<TagDecl>(D)->getDefinition();
1317  assert(CurContext && "skipping definition of undefined tag");
1318  // Start lookups from the parent of the current context; we don't want to look
1319  // into the pre-existing complete definition.
1320  S->setEntity(CurContext->getLookupParent());
1321  return Result;
1322 }
1323 
1325  CurContext = static_cast<decltype(CurContext)>(Context);
1326 }
1327 
1328 /// EnterDeclaratorContext - Used when we must lookup names in the context
1329 /// of a declarator's nested name specifier.
1330 ///
1332  // C++0x [basic.lookup.unqual]p13:
1333  // A name used in the definition of a static data member of class
1334  // X (after the qualified-id of the static member) is looked up as
1335  // if the name was used in a member function of X.
1336  // C++0x [basic.lookup.unqual]p14:
1337  // If a variable member of a namespace is defined outside of the
1338  // scope of its namespace then any name used in the definition of
1339  // the variable member (after the declarator-id) is looked up as
1340  // if the definition of the variable member occurred in its
1341  // namespace.
1342  // Both of these imply that we should push a scope whose context
1343  // is the semantic context of the declaration. We can't use
1344  // PushDeclContext here because that context is not necessarily
1345  // lexically contained in the current context. Fortunately,
1346  // the containing scope should have the appropriate information.
1347 
1348  assert(!S->getEntity() && "scope already has entity");
1349 
1350 #ifndef NDEBUG
1351  Scope *Ancestor = S->getParent();
1352  while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
1353  assert(Ancestor->getEntity() == CurContext && "ancestor context mismatch");
1354 #endif
1355 
1356  CurContext = DC;
1357  S->setEntity(DC);
1358 
1359  if (S->getParent()->isTemplateParamScope()) {
1360  // Also set the corresponding entities for all immediately-enclosing
1361  // template parameter scopes.
1362  EnterTemplatedContext(S->getParent(), DC);
1363  }
1364 }
1365 
1367  assert(S->getEntity() == CurContext && "Context imbalance!");
1368 
1369  // Switch back to the lexical context. The safety of this is
1370  // enforced by an assert in EnterDeclaratorContext.
1371  Scope *Ancestor = S->getParent();
1372  while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
1373  CurContext = Ancestor->getEntity();
1374 
1375  // We don't need to do anything with the scope, which is going to
1376  // disappear.
1377 }
1378 
1380  assert(S->isTemplateParamScope() &&
1381  "expected to be initializing a template parameter scope");
1382 
1383  // C++20 [temp.local]p7:
1384  // In the definition of a member of a class template that appears outside
1385  // of the class template definition, the name of a member of the class
1386  // template hides the name of a template-parameter of any enclosing class
1387  // templates (but not a template-parameter of the member if the member is a
1388  // class or function template).
1389  // C++20 [temp.local]p9:
1390  // In the definition of a class template or in the definition of a member
1391  // of such a template that appears outside of the template definition, for
1392  // each non-dependent base class (13.8.2.1), if the name of the base class
1393  // or the name of a member of the base class is the same as the name of a
1394  // template-parameter, the base class name or member name hides the
1395  // template-parameter name (6.4.10).
1396  //
1397  // This means that a template parameter scope should be searched immediately
1398  // after searching the DeclContext for which it is a template parameter
1399  // scope. For example, for
1400  // template<typename T> template<typename U> template<typename V>
1401  // void N::A<T>::B<U>::f(...)
1402  // we search V then B<U> (and base classes) then U then A<T> (and base
1403  // classes) then T then N then ::.
1404  unsigned ScopeDepth = getTemplateDepth(S);
1405  for (; S && S->isTemplateParamScope(); S = S->getParent(), --ScopeDepth) {
1406  DeclContext *SearchDCAfterScope = DC;
1407  for (; DC; DC = DC->getLookupParent()) {
1408  if (const TemplateParameterList *TPL =
1409  cast<Decl>(DC)->getDescribedTemplateParams()) {
1410  unsigned DCDepth = TPL->getDepth() + 1;
1411  if (DCDepth > ScopeDepth)
1412  continue;
1413  if (ScopeDepth == DCDepth)
1414  SearchDCAfterScope = DC = DC->getLookupParent();
1415  break;
1416  }
1417  }
1418  S->setLookupEntity(SearchDCAfterScope);
1419  }
1420 }
1421 
1423  // We assume that the caller has already called
1424  // ActOnReenterTemplateScope so getTemplatedDecl() works.
1425  FunctionDecl *FD = D->getAsFunction();
1426  if (!FD)
1427  return;
1428 
1429  // Same implementation as PushDeclContext, but enters the context
1430  // from the lexical parent, rather than the top-level class.
1431  assert(CurContext == FD->getLexicalParent() &&
1432  "The next DeclContext should be lexically contained in the current one.");
1433  CurContext = FD;
1434  S->setEntity(CurContext);
1435 
1436  for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
1437  ParmVarDecl *Param = FD->getParamDecl(P);
1438  // If the parameter has an identifier, then add it to the scope
1439  if (Param->getIdentifier()) {
1440  S->AddDecl(Param);
1441  IdResolver.AddDecl(Param);
1442  }
1443  }
1444 }
1445 
1447  // Same implementation as PopDeclContext, but returns to the lexical parent,
1448  // rather than the top-level class.
1449  assert(CurContext && "DeclContext imbalance!");
1450  CurContext = CurContext->getLexicalParent();
1451  assert(CurContext && "Popped translation unit!");
1452 }
1453 
1454 /// Determine whether we allow overloading of the function
1455 /// PrevDecl with another declaration.
1456 ///
1457 /// This routine determines whether overloading is possible, not
1458 /// whether some new function is actually an overload. It will return
1459 /// true in C++ (where we can always provide overloads) or, as an
1460 /// extension, in C when the previous function is already an
1461 /// overloaded function declaration or has the "overloadable"
1462 /// attribute.
1464  ASTContext &Context,
1465  const FunctionDecl *New) {
1466  if (Context.getLangOpts().CPlusPlus)
1467  return true;
1468 
1469  if (Previous.getResultKind() == LookupResult::FoundOverloaded)
1470  return true;
1471 
1472  return Previous.getResultKind() == LookupResult::Found &&
1473  (Previous.getFoundDecl()->hasAttr<OverloadableAttr>() ||
1474  New->hasAttr<OverloadableAttr>());
1475 }
1476 
1477 /// Add this decl to the scope shadowed decl chains.
1478 void Sema::PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext) {
1479  // Move up the scope chain until we find the nearest enclosing
1480  // non-transparent context. The declaration will be introduced into this
1481  // scope.
1482  while (S->getEntity() && S->getEntity()->isTransparentContext())
1483  S = S->getParent();
1484 
1485  // Add scoped declarations into their context, so that they can be
1486  // found later. Declarations without a context won't be inserted
1487  // into any context.
1488  if (AddToContext)
1489  CurContext->addDecl(D);
1490 
1491  // Out-of-line definitions shouldn't be pushed into scope in C++, unless they
1492  // are function-local declarations.
1493  if (getLangOpts().CPlusPlus && D->isOutOfLine() && !S->getFnParent())
1494  return;
1495 
1496  // Template instantiations should also not be pushed into scope.
1497  if (isa<FunctionDecl>(D) &&
1498  cast<FunctionDecl>(D)->isFunctionTemplateSpecialization())
1499  return;
1500 
1501  // If this replaces anything in the current scope,
1502  IdentifierResolver::iterator I = IdResolver.begin(D->getDeclName()),
1503  IEnd = IdResolver.end();
1504  for (; I != IEnd; ++I) {
1505  if (S->isDeclScope(*I) && D->declarationReplaces(*I)) {
1506  S->RemoveDecl(*I);
1507  IdResolver.RemoveDecl(*I);
1508 
1509  // Should only need to replace one decl.
1510  break;
1511  }
1512  }
1513 
1514  S->AddDecl(D);
1515 
1516  if (isa<LabelDecl>(D) && !cast<LabelDecl>(D)->isGnuLocal()) {
1517  // Implicitly-generated labels may end up getting generated in an order that
1518  // isn't strictly lexical, which breaks name lookup. Be careful to insert
1519  // the label at the appropriate place in the identifier chain.
1520  for (I = IdResolver.begin(D->getDeclName()); I != IEnd; ++I) {
1521  DeclContext *IDC = (*I)->getLexicalDeclContext()->getRedeclContext();
1522  if (IDC == CurContext) {
1523  if (!S->isDeclScope(*I))
1524  continue;
1525  } else if (IDC->Encloses(CurContext))
1526  break;
1527  }
1528 
1529  IdResolver.InsertDeclAfter(I, D);
1530  } else {
1531  IdResolver.AddDecl(D);
1532  }
1533  warnOnReservedIdentifier(D);
1534 }
1535 
1537  bool AllowInlineNamespace) {
1538  return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
1539 }
1540 
1542  DeclContext *TargetDC = DC->getPrimaryContext();
1543  do {
1544  if (DeclContext *ScopeDC = S->getEntity())
1545  if (ScopeDC->getPrimaryContext() == TargetDC)
1546  return S;
1547  } while ((S = S->getParent()));
1548 
1549  return nullptr;
1550 }
1551 
1553  DeclContext*,
1554  ASTContext&);
1555 
1556 /// Filters out lookup results that don't fall within the given scope
1557 /// as determined by isDeclInScope.
1559  bool ConsiderLinkage,
1560  bool AllowInlineNamespace) {
1562  while (F.hasNext()) {
1563  NamedDecl *D = F.next();
1564 
1565  if (isDeclInScope(D, Ctx, S, AllowInlineNamespace))
1566  continue;
1567 
1568  if (ConsiderLinkage && isOutOfScopePreviousDeclaration(D, Ctx, Context))
1569  continue;
1570 
1571  F.erase();
1572  }
1573 
1574  F.done();
1575 }
1576 
1577 /// We've determined that \p New is a redeclaration of \p Old. Check that they
1578 /// have compatible owning modules.
1580  // FIXME: The Modules TS is not clear about how friend declarations are
1581  // to be treated. It's not meaningful to have different owning modules for
1582  // linkage in redeclarations of the same entity, so for now allow the
1583  // redeclaration and change the owning modules to match.
1584  if (New->getFriendObjectKind() &&
1587  makeMergedDefinitionVisible(New);
1588  return false;
1589  }
1590 
1591  Module *NewM = New->getOwningModule();
1592  Module *OldM = Old->getOwningModule();
1593 
1594  if (NewM && NewM->Kind == Module::PrivateModuleFragment)
1595  NewM = NewM->Parent;
1596  if (OldM && OldM->Kind == Module::PrivateModuleFragment)
1597  OldM = OldM->Parent;
1598 
1599  if (NewM == OldM)
1600  return false;
1601 
1602  bool NewIsModuleInterface = NewM && NewM->isModulePurview();
1603  bool OldIsModuleInterface = OldM && OldM->isModulePurview();
1604  if (NewIsModuleInterface || OldIsModuleInterface) {
1605  // C++ Modules TS [basic.def.odr] 6.2/6.7 [sic]:
1606  // if a declaration of D [...] appears in the purview of a module, all
1607  // other such declarations shall appear in the purview of the same module
1608  Diag(New->getLocation(), diag::err_mismatched_owning_module)
1609  << New
1610  << NewIsModuleInterface
1611  << (NewIsModuleInterface ? NewM->getFullModuleName() : "")
1612  << OldIsModuleInterface
1613  << (OldIsModuleInterface ? OldM->getFullModuleName() : "");
1614  Diag(Old->getLocation(), diag::note_previous_declaration);
1615  New->setInvalidDecl();
1616  return true;
1617  }
1618 
1619  return false;
1620 }
1621 
1622 static bool isUsingDecl(NamedDecl *D) {
1623  return isa<UsingShadowDecl>(D) ||
1624  isa<UnresolvedUsingTypenameDecl>(D) ||
1625  isa<UnresolvedUsingValueDecl>(D);
1626 }
1627 
1628 /// Removes using shadow declarations from the lookup results.
1631  while (F.hasNext())
1632  if (isUsingDecl(F.next()))
1633  F.erase();
1634 
1635  F.done();
1636 }
1637 
1638 /// Check for this common pattern:
1639 /// @code
1640 /// class S {
1641 /// S(const S&); // DO NOT IMPLEMENT
1642 /// void operator=(const S&); // DO NOT IMPLEMENT
1643 /// };
1644 /// @endcode
1646  // FIXME: Should check for private access too but access is set after we get
1647  // the decl here.
1649  return false;
1650 
1651  if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
1652  return CD->isCopyConstructor();
1653  return D->isCopyAssignmentOperator();
1654 }
1655 
1656 // We need this to handle
1657 //
1658 // typedef struct {
1659 // void *foo() { return 0; }
1660 // } A;
1661 //
1662 // When we see foo we don't know if after the typedef we will get 'A' or '*A'
1663 // for example. If 'A', foo will have external linkage. If we have '*A',
1664 // foo will have no linkage. Since we can't know until we get to the end
1665 // of the typedef, this function finds out if D might have non-external linkage.
1666 // Callers should verify at the end of the TU if it D has external linkage or
1667 // not.
1668 bool Sema::mightHaveNonExternalLinkage(const DeclaratorDecl *D) {
1669  const DeclContext *DC = D->getDeclContext();
1670  while (!DC->isTranslationUnit()) {
1671  if (const RecordDecl *RD = dyn_cast<RecordDecl>(DC)){
1672  if (!RD->hasNameForLinkage())
1673  return true;
1674  }
1675  DC = DC->getParent();
1676  }
1677 
1678  return !D->isExternallyVisible();
1679 }
1680 
1681 // FIXME: This needs to be refactored; some other isInMainFile users want
1682 // these semantics.
1683 static bool isMainFileLoc(const Sema &S, SourceLocation Loc) {
1684  if (S.TUKind != TU_Complete)
1685  return false;
1686  return S.SourceMgr.isInMainFile(Loc);
1687 }
1688 
1690  assert(D);
1691 
1692  if (D->isInvalidDecl() || D->isUsed() || D->hasAttr<UnusedAttr>())
1693  return false;
1694 
1695  // Ignore all entities declared within templates, and out-of-line definitions
1696  // of members of class templates.
1697  if (D->getDeclContext()->isDependentContext() ||
1699  return false;
1700 
1701  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1702  if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
1703  return false;
1704  // A non-out-of-line declaration of a member specialization was implicitly
1705  // instantiated; it's the out-of-line declaration that we're interested in.
1706  if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
1707  FD->getMemberSpecializationInfo() && !FD->isOutOfLine())
1708  return false;
1709 
1710  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
1711  if (MD->isVirtual() || IsDisallowedCopyOrAssign(MD))
1712  return false;
1713  } else {
1714  // 'static inline' functions are defined in headers; don't warn.
1715  if (FD->isInlined() && !isMainFileLoc(*this, FD->getLocation()))
1716  return false;
1717  }
1718 
1719  if (FD->doesThisDeclarationHaveABody() &&
1720  Context.DeclMustBeEmitted(FD))
1721  return false;
1722  } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1723  // Constants and utility variables are defined in headers with internal
1724  // linkage; don't warn. (Unlike functions, there isn't a convenient marker
1725  // like "inline".)
1726  if (!isMainFileLoc(*this, VD->getLocation()))
1727  return false;
1728 
1729  if (Context.DeclMustBeEmitted(VD))
1730  return false;
1731 
1732  if (VD->isStaticDataMember() &&
1733  VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
1734  return false;
1735  if (VD->isStaticDataMember() &&
1736  VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
1737  VD->getMemberSpecializationInfo() && !VD->isOutOfLine())
1738  return false;
1739 
1740  if (VD->isInline() && !isMainFileLoc(*this, VD->getLocation()))
1741  return false;
1742  } else {
1743  return false;
1744  }
1745 
1746  // Only warn for unused decls internal to the translation unit.
1747  // FIXME: This seems like a bogus check; it suppresses -Wunused-function
1748  // for inline functions defined in the main source file, for instance.
1749  return mightHaveNonExternalLinkage(D);
1750 }
1751 
1753  if (!D)
1754  return;
1755 
1756  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
1757  const FunctionDecl *First = FD->getFirstDecl();
1758  if (FD != First && ShouldWarnIfUnusedFileScopedDecl(First))
1759  return; // First should already be in the vector.
1760  }
1761 
1762  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1763  const VarDecl *First = VD->getFirstDecl();
1764  if (VD != First && ShouldWarnIfUnusedFileScopedDecl(First))
1765  return; // First should already be in the vector.
1766  }
1767 
1768  if (ShouldWarnIfUnusedFileScopedDecl(D))
1769  UnusedFileScopedDecls.push_back(D);
1770 }
1771 
1772 static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
1773  if (D->isInvalidDecl())
1774  return false;
1775 
1776  if (auto *DD = dyn_cast<DecompositionDecl>(D)) {
1777  // For a decomposition declaration, warn if none of the bindings are
1778  // referenced, instead of if the variable itself is referenced (which
1779  // it is, by the bindings' expressions).
1780  for (auto *BD : DD->bindings())
1781  if (BD->isReferenced())
1782  return false;
1783  } else if (!D->getDeclName()) {
1784  return false;
1785  } else if (D->isReferenced() || D->isUsed()) {
1786  return false;
1787  }
1788 
1789  if (D->hasAttr<UnusedAttr>() || D->hasAttr<ObjCPreciseLifetimeAttr>())
1790  return false;
1791 
1792  if (isa<LabelDecl>(D))
1793  return true;
1794 
1795  // Except for labels, we only care about unused decls that are local to
1796  // functions.
1797  bool WithinFunction = D->getDeclContext()->isFunctionOrMethod();
1798  if (const auto *R = dyn_cast<CXXRecordDecl>(D->getDeclContext()))
1799  // For dependent types, the diagnostic is deferred.
1800  WithinFunction =
1801  WithinFunction || (R->isLocalClass() && !R->isDependentType());
1802  if (!WithinFunction)
1803  return false;
1804 
1805  if (isa<TypedefNameDecl>(D))
1806  return true;
1807 
1808  // White-list anything that isn't a local variable.
1809  if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D))
1810  return false;
1811 
1812  // Types of valid local variables should be complete, so this should succeed.
1813  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
1814 
1815  // White-list anything with an __attribute__((unused)) type.
1816  const auto *Ty = VD->getType().getTypePtr();
1817 
1818  // Only look at the outermost level of typedef.
1819  if (const TypedefType *TT = Ty->getAs<TypedefType>()) {
1820  if (TT->getDecl()->hasAttr<UnusedAttr>())
1821  return false;
1822  }
1823 
1824  // If we failed to complete the type for some reason, or if the type is
1825  // dependent, don't diagnose the variable.
1826  if (Ty->isIncompleteType() || Ty->isDependentType())
1827  return false;
1828 
1829  // Look at the element type to ensure that the warning behaviour is
1830  // consistent for both scalars and arrays.
1831  Ty = Ty->getBaseElementTypeUnsafe();
1832 
1833  if (const TagType *TT = Ty->getAs<TagType>()) {
1834  const TagDecl *Tag = TT->getDecl();
1835  if (Tag->hasAttr<UnusedAttr>())
1836  return false;
1837 
1838  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
1839  if (!RD->hasTrivialDestructor() && !RD->hasAttr<WarnUnusedAttr>())
1840  return false;
1841 
1842  if (const Expr *Init = VD->getInit()) {
1843  if (const ExprWithCleanups *Cleanups =
1844  dyn_cast<ExprWithCleanups>(Init))
1845  Init = Cleanups->getSubExpr();
1846  const CXXConstructExpr *Construct =
1847  dyn_cast<CXXConstructExpr>(Init);
1848  if (Construct && !Construct->isElidable()) {
1849  CXXConstructorDecl *CD = Construct->getConstructor();
1850  if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
1851  (VD->getInit()->isValueDependent() || !VD->evaluateValue()))
1852  return false;
1853  }
1854 
1855  // Suppress the warning if we don't know how this is constructed, and
1856  // it could possibly be non-trivial constructor.
1857  if (Init->isTypeDependent())
1858  for (const CXXConstructorDecl *Ctor : RD->ctors())
1859  if (!Ctor->isTrivial())
1860  return false;
1861  }
1862  }
1863  }
1864 
1865  // TODO: __attribute__((unused)) templates?
1866  }
1867 
1868  return true;
1869 }
1870 
1871 static void GenerateFixForUnusedDecl(const NamedDecl *D, ASTContext &Ctx,
1872  FixItHint &Hint) {
1873  if (isa<LabelDecl>(D)) {
1875  D->getEndLoc(), tok::colon, Ctx.getSourceManager(), Ctx.getLangOpts(),
1876  true);
1877  if (AfterColon.isInvalid())
1878  return;
1879  Hint = FixItHint::CreateRemoval(
1880  CharSourceRange::getCharRange(D->getBeginLoc(), AfterColon));
1881  }
1882 }
1883 
1885  if (D->getTypeForDecl()->isDependentType())
1886  return;
1887 
1888  for (auto *TmpD : D->decls()) {
1889  if (const auto *T = dyn_cast<TypedefNameDecl>(TmpD))
1890  DiagnoseUnusedDecl(T);
1891  else if(const auto *R = dyn_cast<RecordDecl>(TmpD))
1892  DiagnoseUnusedNestedTypedefs(R);
1893  }
1894 }
1895 
1896 /// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
1897 /// unless they are marked attr(unused).
1899  if (!ShouldDiagnoseUnusedDecl(D))
1900  return;
1901 
1902  if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
1903  // typedefs can be referenced later on, so the diagnostics are emitted
1904  // at end-of-translation-unit.
1905  UnusedLocalTypedefNameCandidates.insert(TD);
1906  return;
1907  }
1908 
1909  FixItHint Hint;
1910  GenerateFixForUnusedDecl(D, Context, Hint);
1911 
1912  unsigned DiagID;
1913  if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
1914  DiagID = diag::warn_unused_exception_param;
1915  else if (isa<LabelDecl>(D))
1916  DiagID = diag::warn_unused_label;
1917  else
1918  DiagID = diag::warn_unused_variable;
1919 
1920  Diag(D->getLocation(), DiagID) << D << Hint;
1921 }
1922 
1924  // If it's not referenced, it can't be set. If it has the Cleanup attribute,
1925  // it's not really unused.
1926  if (!VD->isReferenced() || !VD->getDeclName() || VD->hasAttr<UnusedAttr>() ||
1927  VD->hasAttr<CleanupAttr>())
1928  return;
1929 
1930  const auto *Ty = VD->getType().getTypePtr()->getBaseElementTypeUnsafe();
1931 
1932  if (Ty->isReferenceType() || Ty->isDependentType())
1933  return;
1934 
1935  if (const TagType *TT = Ty->getAs<TagType>()) {
1936  const TagDecl *Tag = TT->getDecl();
1937  if (Tag->hasAttr<UnusedAttr>())
1938  return;
1939  // In C++, don't warn for record types that don't have WarnUnusedAttr, to
1940  // mimic gcc's behavior.
1941  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
1942  if (!RD->hasAttr<WarnUnusedAttr>())
1943  return;
1944  }
1945  }
1946 
1947  auto iter = RefsMinusAssignments.find(VD);
1948  if (iter == RefsMinusAssignments.end())
1949  return;
1950 
1951  assert(iter->getSecond() >= 0 &&
1952  "Found a negative number of references to a VarDecl");
1953  if (iter->getSecond() != 0)
1954  return;
1955  unsigned DiagID = isa<ParmVarDecl>(VD) ? diag::warn_unused_but_set_parameter
1956  : diag::warn_unused_but_set_variable;
1957  Diag(VD->getLocation(), DiagID) << VD;
1958 }
1959 
1960 static void CheckPoppedLabel(LabelDecl *L, Sema &S) {
1961  // Verify that we have no forward references left. If so, there was a goto
1962  // or address of a label taken, but no definition of it. Label fwd
1963  // definitions are indicated with a null substmt which is also not a resolved
1964  // MS inline assembly label name.
1965  bool Diagnose = false;
1966  if (L->isMSAsmLabel())
1967  Diagnose = !L->isResolvedMSAsmLabel();
1968  else
1969  Diagnose = L->getStmt() == nullptr;
1970  if (Diagnose)
1971  S.Diag(L->getLocation(), diag::err_undeclared_label_use) << L;
1972 }
1973 
1975  S->mergeNRVOIntoParent();
1976 
1977  if (S->decl_empty()) return;
1978  assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&
1979  "Scope shouldn't contain decls!");
1980 
1981  for (auto *TmpD : S->decls()) {
1982  assert(TmpD && "This decl didn't get pushed??");
1983 
1984  assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?");
1985  NamedDecl *D = cast<NamedDecl>(TmpD);
1986 
1987  // Diagnose unused variables in this scope.
1988  if (!S->hasUnrecoverableErrorOccurred()) {
1989  DiagnoseUnusedDecl(D);
1990  if (const auto *RD = dyn_cast<RecordDecl>(D))
1991  DiagnoseUnusedNestedTypedefs(RD);
1992  if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
1993  DiagnoseUnusedButSetDecl(VD);
1994  RefsMinusAssignments.erase(VD);
1995  }
1996  }
1997 
1998  if (!D->getDeclName()) continue;
1999 
2000  // If this was a forward reference to a label, verify it was defined.
2001  if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
2002  CheckPoppedLabel(LD, *this);
2003 
2004  // Remove this name from our lexical scope, and warn on it if we haven't
2005  // already.
2006  IdResolver.RemoveDecl(D);
2007  auto ShadowI = ShadowingDecls.find(D);
2008  if (ShadowI != ShadowingDecls.end()) {
2009  if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {
2010  Diag(D->getLocation(), diag::warn_ctor_parm_shadows_field)
2011  << D << FD << FD->getParent();
2012  Diag(FD->getLocation(), diag::note_previous_declaration);
2013  }
2014  ShadowingDecls.erase(ShadowI);
2015  }
2016  }
2017 }
2018 
2019 /// Look for an Objective-C class in the translation unit.
2020 ///
2021 /// \param Id The name of the Objective-C class we're looking for. If
2022 /// typo-correction fixes this name, the Id will be updated
2023 /// to the fixed name.
2024 ///
2025 /// \param IdLoc The location of the name in the translation unit.
2026 ///
2027 /// \param DoTypoCorrection If true, this routine will attempt typo correction
2028 /// if there is no class with the given name.
2029 ///
2030 /// \returns The declaration of the named Objective-C class, or NULL if the
2031 /// class could not be found.
2033  SourceLocation IdLoc,
2034  bool DoTypoCorrection) {
2035  // The third "scope" argument is 0 since we aren't enabling lazy built-in
2036  // creation from this context.
2037  NamedDecl *IDecl = LookupSingleName(TUScope, Id, IdLoc, LookupOrdinaryName);
2038 
2039  if (!IDecl && DoTypoCorrection) {
2040  // Perform typo correction at the given location, but only if we
2041  // find an Objective-C class name.
2043  if (TypoCorrection C =
2044  CorrectTypo(DeclarationNameInfo(Id, IdLoc), LookupOrdinaryName,
2045  TUScope, nullptr, CCC, CTK_ErrorRecovery)) {
2046  diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
2047  IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
2048  Id = IDecl->getIdentifier();
2049  }
2050  }
2051  ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
2052  // This routine must always return a class definition, if any.
2053  if (Def && Def->getDefinition())
2054  Def = Def->getDefinition();
2055  return Def;
2056 }
2057 
2058 /// getNonFieldDeclScope - Retrieves the innermost scope, starting
2059 /// from S, where a non-field would be declared. This routine copes
2060 /// with the difference between C and C++ scoping rules in structs and
2061 /// unions. For example, the following code is well-formed in C but
2062 /// ill-formed in C++:
2063 /// @code
2064 /// struct S6 {
2065 /// enum { BAR } e;
2066 /// };
2067 ///
2068 /// void test_S6() {
2069 /// struct S6 a;
2070 /// a.e = BAR;
2071 /// }
2072 /// @endcode
2073 /// For the declaration of BAR, this routine will return a different
2074 /// scope. The scope S will be the scope of the unnamed enumeration
2075 /// within S6. In C++, this routine will return the scope associated
2076 /// with S6, because the enumeration's scope is a transparent
2077 /// context but structures can contain non-field names. In C, this
2078 /// routine will return the translation unit scope, since the
2079 /// enumeration's scope is a transparent context and structures cannot
2080 /// contain non-field names.
2082  while (((S->getFlags() & Scope::DeclScope) == 0) ||
2083  (S->getEntity() && S->getEntity()->isTransparentContext()) ||
2084  (S->isClassScope() && !getLangOpts().CPlusPlus))
2085  S = S->getParent();
2086  return S;
2087 }
2088 
2089 static StringRef getHeaderName(Builtin::Context &BuiltinInfo, unsigned ID,
2091  switch (Error) {
2092  case ASTContext::GE_None:
2093  return "";
2095  return BuiltinInfo.getHeaderName(ID);
2097  return "stdio.h";
2099  return "setjmp.h";
2101  return "ucontext.h";
2102  }
2103  llvm_unreachable("unhandled error kind");
2104 }
2105 
2107  unsigned ID, SourceLocation Loc) {
2109 
2110  if (getLangOpts().CPlusPlus) {
2111  LinkageSpecDecl *CLinkageDecl = LinkageSpecDecl::Create(
2112  Context, Parent, Loc, Loc, LinkageSpecDecl::lang_c, false);
2113  CLinkageDecl->setImplicit();
2114  Parent->addDecl(CLinkageDecl);
2115  Parent = CLinkageDecl;
2116  }
2117 
2118  FunctionDecl *New = FunctionDecl::Create(Context, Parent, Loc, Loc, II, Type,
2119  /*TInfo=*/nullptr, SC_Extern,
2120  getCurFPFeatures().isFPConstrained(),
2121  false, Type->isFunctionProtoType());
2122  New->setImplicit();
2123  New->addAttr(BuiltinAttr::CreateImplicit(Context, ID));
2124 
2125  // Create Decl objects for each parameter, adding them to the
2126  // FunctionDecl.
2127  if (const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(Type)) {
2129  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
2131  Context, New, SourceLocation(), SourceLocation(), nullptr,
2132  FT->getParamType(i), /*TInfo=*/nullptr, SC_None, nullptr);
2133  parm->setScopeInfo(0, i);
2134  Params.push_back(parm);
2135  }
2136  New->setParams(Params);
2137  }
2138 
2139  AddKnownFunctionAttributes(New);
2140  return New;
2141 }
2142 
2143 /// LazilyCreateBuiltin - The specified Builtin-ID was first used at
2144 /// file scope. lazily create a decl for it. ForRedeclaration is true
2145 /// if we're creating this built-in in anticipation of redeclaring the
2146 /// built-in.
2148  Scope *S, bool ForRedeclaration,
2149  SourceLocation Loc) {
2150  LookupNecessaryTypesForBuiltin(S, ID);
2151 
2153  QualType R = Context.GetBuiltinType(ID, Error);
2154  if (Error) {
2155  if (!ForRedeclaration)
2156  return nullptr;
2157 
2158  // If we have a builtin without an associated type we should not emit a
2159  // warning when we were not able to find a type for it.
2161  Context.BuiltinInfo.allowTypeMismatch(ID))
2162  return nullptr;
2163 
2164  // If we could not find a type for setjmp it is because the jmp_buf type was
2165  // not defined prior to the setjmp declaration.
2167  Diag(Loc, diag::warn_implicit_decl_no_jmp_buf)
2168  << Context.BuiltinInfo.getName(ID);
2169  return nullptr;
2170  }
2171 
2172  // Generally, we emit a warning that the declaration requires the
2173  // appropriate header.
2174  Diag(Loc, diag::warn_implicit_decl_requires_sysheader)
2175  << getHeaderName(Context.BuiltinInfo, ID, Error)
2176  << Context.BuiltinInfo.getName(ID);
2177  return nullptr;
2178  }
2179 
2180  if (!ForRedeclaration &&
2183  Diag(Loc, diag::ext_implicit_lib_function_decl)
2184  << Context.BuiltinInfo.getName(ID) << R;
2185  if (const char *Header = Context.BuiltinInfo.getHeaderName(ID))
2186  Diag(Loc, diag::note_include_header_or_declare)
2187  << Header << Context.BuiltinInfo.getName(ID);
2188  }
2189 
2190  if (R.isNull())
2191  return nullptr;
2192 
2193  FunctionDecl *New = CreateBuiltin(II, R, ID, Loc);
2194  RegisterLocallyScopedExternCDecl(New, S);
2195 
2196  // TUScope is the translation-unit scope to insert this function into.
2197  // FIXME: This is hideous. We need to teach PushOnScopeChains to
2198  // relate Scopes to DeclContexts, and probably eliminate CurContext
2199  // entirely, but we're not there yet.
2200  DeclContext *SavedContext = CurContext;
2201  CurContext = New->getDeclContext();
2202  PushOnScopeChains(New, TUScope);
2203  CurContext = SavedContext;
2204  return New;
2205 }
2206 
2207 /// Typedef declarations don't have linkage, but they still denote the same
2208 /// entity if their types are the same.
2209 /// FIXME: This is notionally doing the same thing as ASTReaderDecl's
2210 /// isSameEntity.
2214  // This is only interesting when modules are enabled.
2215  if (!S.getLangOpts().Modules && !S.getLangOpts().ModulesLocalVisibility)
2216  return;
2217 
2218  // Empty sets are uninteresting.
2219  if (Previous.empty())
2220  return;
2221 
2222  LookupResult::Filter Filter = Previous.makeFilter();
2223  while (Filter.hasNext()) {
2224  NamedDecl *Old = Filter.next();
2225 
2226  // Non-hidden declarations are never ignored.
2227  if (S.isVisible(Old))
2228  continue;
2229 
2230  // Declarations of the same entity are not ignored, even if they have
2231  // different linkages.
2232  if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
2233  if (S.Context.hasSameType(OldTD->getUnderlyingType(),
2234  Decl->getUnderlyingType()))
2235  continue;
2236 
2237  // If both declarations give a tag declaration a typedef name for linkage
2238  // purposes, then they declare the same entity.
2239  if (OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true) &&
2240  Decl->getAnonDeclWithTypedefName())
2241  continue;
2242  }
2243 
2244  Filter.erase();
2245  }
2246 
2247  Filter.done();
2248 }
2249 
2251  QualType OldType;
2252  if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
2253  OldType = OldTypedef->getUnderlyingType();
2254  else
2255  OldType = Context.getTypeDeclType(Old);
2256  QualType NewType = New->getUnderlyingType();
2257 
2258  if (NewType->isVariablyModifiedType()) {
2259  // Must not redefine a typedef with a variably-modified type.
2260  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
2261  Diag(New->getLocation(), diag::err_redefinition_variably_modified_typedef)
2262  << Kind << NewType;
2263  if (Old->getLocation().isValid())
2264  notePreviousDefinition(Old, New->getLocation());
2265  New->setInvalidDecl();
2266  return true;
2267  }
2268 
2269  if (OldType != NewType &&
2270  !OldType->isDependentType() &&
2271  !NewType->isDependentType() &&
2272  !Context.hasSameType(OldType, NewType)) {
2273  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
2274  Diag(New->getLocation(), diag::err_redefinition_different_typedef)
2275  << Kind << NewType << OldType;
2276  if (Old->getLocation().isValid())
2277  notePreviousDefinition(Old, New->getLocation());
2278  New->setInvalidDecl();
2279  return true;
2280  }
2281  return false;
2282 }
2283 
2284 /// MergeTypedefNameDecl - We just parsed a typedef 'New' which has the
2285 /// same name and scope as a previous declaration 'Old'. Figure out
2286 /// how to resolve this situation, merging decls or emitting
2287 /// diagnostics as appropriate. If there was an error, set New to be invalid.
2288 ///
2290  LookupResult &OldDecls) {
2291  // If the new decl is known invalid already, don't bother doing any
2292  // merging checks.
2293  if (New->isInvalidDecl()) return;
2294 
2295  // Allow multiple definitions for ObjC built-in typedefs.
2296  // FIXME: Verify the underlying types are equivalent!
2297  if (getLangOpts().ObjC) {
2298  const IdentifierInfo *TypeID = New->getIdentifier();
2299  switch (TypeID->getLength()) {
2300  default: break;
2301  case 2:
2302  {
2303  if (!TypeID->isStr("id"))
2304  break;
2305  QualType T = New->getUnderlyingType();
2306  if (!T->isPointerType())
2307  break;
2308  if (!T->isVoidPointerType()) {
2309  QualType PT = T->castAs<PointerType>()->getPointeeType();
2310  if (!PT->isStructureType())
2311  break;
2312  }
2313  Context.setObjCIdRedefinitionType(T);
2314  // Install the built-in type for 'id', ignoring the current definition.
2315  New->setTypeForDecl(Context.getObjCIdType().getTypePtr());
2316  return;
2317  }
2318  case 5:
2319  if (!TypeID->isStr("Class"))
2320  break;
2322  // Install the built-in type for 'Class', ignoring the current definition.
2323  New->setTypeForDecl(Context.getObjCClassType().getTypePtr());
2324  return;
2325  case 3:
2326  if (!TypeID->isStr("SEL"))
2327  break;
2329  // Install the built-in type for 'SEL', ignoring the current definition.
2330  New->setTypeForDecl(Context.getObjCSelType().getTypePtr());
2331  return;
2332  }
2333  // Fall through - the typedef name was not a builtin type.
2334  }
2335 
2336  // Verify the old decl was also a type.
2337  TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
2338  if (!Old) {
2339  Diag(New->getLocation(), diag::err_redefinition_different_kind)
2340  << New->getDeclName();
2341 
2342  NamedDecl *OldD = OldDecls.getRepresentativeDecl();
2343  if (OldD->getLocation().isValid())
2344  notePreviousDefinition(OldD, New->getLocation());
2345 
2346  return New->setInvalidDecl();
2347  }
2348 
2349  // If the old declaration is invalid, just give up here.
2350  if (Old->isInvalidDecl())
2351  return New->setInvalidDecl();
2352 
2353  if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
2354  auto *OldTag = OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
2355  auto *NewTag = New->getAnonDeclWithTypedefName();
2356  NamedDecl *Hidden = nullptr;
2357  if (OldTag && NewTag &&
2358  OldTag->getCanonicalDecl() != NewTag->getCanonicalDecl() &&
2359  !hasVisibleDefinition(OldTag, &Hidden)) {
2360  // There is a definition of this tag, but it is not visible. Use it
2361  // instead of our tag.
2362  New->setTypeForDecl(OldTD->getTypeForDecl());
2363  if (OldTD->isModed())
2364  New->setModedTypeSourceInfo(OldTD->getTypeSourceInfo(),
2365  OldTD->getUnderlyingType());
2366  else
2367  New->setTypeSourceInfo(OldTD->getTypeSourceInfo());
2368 
2369  // Make the old tag definition visible.
2370  makeMergedDefinitionVisible(Hidden);
2371 
2372  // If this was an unscoped enumeration, yank all of its enumerators
2373  // out of the scope.
2374  if (isa<EnumDecl>(NewTag)) {
2375  Scope *EnumScope = getNonFieldDeclScope(S);
2376  for (auto *D : NewTag->decls()) {
2377  auto *ED = cast<EnumConstantDecl>(D);
2378  assert(EnumScope->isDeclScope(ED));
2379  EnumScope->RemoveDecl(ED);
2380  IdResolver.RemoveDecl(ED);
2381  ED->getLexicalDeclContext()->removeDecl(ED);
2382  }
2383  }
2384  }
2385  }
2386 
2387  // If the typedef types are not identical, reject them in all languages and
2388  // with any extensions enabled.
2389  if (isIncompatibleTypedef(Old, New))
2390  return;
2391 
2392  // The types match. Link up the redeclaration chain and merge attributes if
2393  // the old declaration was a typedef.
2394  if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Old)) {
2395  New->setPreviousDecl(Typedef);
2396  mergeDeclAttributes(New, Old);
2397  }
2398 
2399  if (getLangOpts().MicrosoftExt)
2400  return;
2401 
2402  if (getLangOpts().CPlusPlus) {
2403  // C++ [dcl.typedef]p2:
2404  // In a given non-class scope, a typedef specifier can be used to
2405  // redefine the name of any type declared in that scope to refer
2406  // to the type to which it already refers.
2407  if (!isa<CXXRecordDecl>(CurContext))
2408  return;
2409 
2410  // C++0x [dcl.typedef]p4:
2411  // In a given class scope, a typedef specifier can be used to redefine
2412  // any class-name declared in that scope that is not also a typedef-name
2413  // to refer to the type to which it already refers.
2414  //
2415  // This wording came in via DR424, which was a correction to the
2416  // wording in DR56, which accidentally banned code like:
2417  //
2418  // struct S {
2419  // typedef struct A { } A;
2420  // };
2421  //
2422  // in the C++03 standard. We implement the C++0x semantics, which
2423  // allow the above but disallow
2424  //
2425  // struct S {
2426  // typedef int I;
2427  // typedef int I;
2428  // };
2429  //
2430  // since that was the intent of DR56.
2431  if (!isa<TypedefNameDecl>(Old))
2432  return;
2433 
2434  Diag(New->getLocation(), diag::err_redefinition)
2435  << New->getDeclName();
2436  notePreviousDefinition(Old, New->getLocation());
2437  return New->setInvalidDecl();
2438  }
2439 
2440  // Modules always permit redefinition of typedefs, as does C11.
2441  if (getLangOpts().Modules || getLangOpts().C11)
2442  return;
2443 
2444  // If we have a redefinition of a typedef in C, emit a warning. This warning
2445  // is normally mapped to an error, but can be controlled with
2446  // -Wtypedef-redefinition. If either the original or the redefinition is
2447  // in a system header, don't emit this for compatibility with GCC.
2448  if (getDiagnostics().getSuppressSystemWarnings() &&
2449  // Some standard types are defined implicitly in Clang (e.g. OpenCL).
2450  (Old->isImplicit() ||
2451  Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
2452  Context.getSourceManager().isInSystemHeader(New->getLocation())))
2453  return;
2454 
2455  Diag(New->getLocation(), diag::ext_redefinition_of_typedef)
2456  << New->getDeclName();
2457  notePreviousDefinition(Old, New->getLocation());
2458 }
2459 
2460 /// DeclhasAttr - returns true if decl Declaration already has the target
2461 /// attribute.
2462 static bool DeclHasAttr(const Decl *D, const Attr *A) {
2463  const OwnershipAttr *OA = dyn_cast<OwnershipAttr>(A);
2464  const AnnotateAttr *Ann = dyn_cast<AnnotateAttr>(A);
2465  for (const auto *i : D->attrs())
2466  if (i->getKind() == A->getKind()) {
2467  if (Ann) {
2468  if (Ann->getAnnotation() == cast<AnnotateAttr>(i)->getAnnotation())
2469  return true;
2470  continue;
2471  }
2472  // FIXME: Don't hardcode this check
2473  if (OA && isa<OwnershipAttr>(i))
2474  return OA->getOwnKind() == cast<OwnershipAttr>(i)->getOwnKind();
2475  return true;
2476  }
2477 
2478  return false;
2479 }
2480 
2482  if (VarDecl *VD = dyn_cast<VarDecl>(D))
2483  return VD->isThisDeclarationADefinition();
2484  if (TagDecl *TD = dyn_cast<TagDecl>(D))
2485  return TD->isCompleteDefinition() || TD->isBeingDefined();
2486  return true;
2487 }
2488 
2489 /// Merge alignment attributes from \p Old to \p New, taking into account the
2490 /// special semantics of C11's _Alignas specifier and C++11's alignas attribute.
2491 ///
2492 /// \return \c true if any attributes were added to \p New.
2493 static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
2494  // Look for alignas attributes on Old, and pick out whichever attribute
2495  // specifies the strictest alignment requirement.
2496  AlignedAttr *OldAlignasAttr = nullptr;
2497  AlignedAttr *OldStrictestAlignAttr = nullptr;
2498  unsigned OldAlign = 0;
2499  for (auto *I : Old->specific_attrs<AlignedAttr>()) {
2500  // FIXME: We have no way of representing inherited dependent alignments
2501  // in a case like:
2502  // template<int A, int B> struct alignas(A) X;
2503  // template<int A, int B> struct alignas(B) X {};
2504  // For now, we just ignore any alignas attributes which are not on the
2505  // definition in such a case.
2506  if (I->isAlignmentDependent())
2507  return false;
2508 
2509  if (I->isAlignas())
2510  OldAlignasAttr = I;
2511 
2512  unsigned Align = I->getAlignment(S.Context);
2513  if (Align > OldAlign) {
2514  OldAlign = Align;
2515  OldStrictestAlignAttr = I;
2516  }
2517  }
2518 
2519  // Look for alignas attributes on New.
2520  AlignedAttr *NewAlignasAttr = nullptr;
2521  unsigned NewAlign = 0;
2522  for (auto *I : New->specific_attrs<AlignedAttr>()) {
2523  if (I->isAlignmentDependent())
2524  return false;
2525 
2526  if (I->isAlignas())
2527  NewAlignasAttr = I;
2528 
2529  unsigned Align = I->getAlignment(S.Context);
2530  if (Align > NewAlign)
2531  NewAlign = Align;
2532  }
2533 
2534  if (OldAlignasAttr && NewAlignasAttr && OldAlign != NewAlign) {
2535  // Both declarations have 'alignas' attributes. We require them to match.
2536  // C++11 [dcl.align]p6 and C11 6.7.5/7 both come close to saying this, but
2537  // fall short. (If two declarations both have alignas, they must both match
2538  // every definition, and so must match each other if there is a definition.)
2539 
2540  // If either declaration only contains 'alignas(0)' specifiers, then it
2541  // specifies the natural alignment for the type.
2542  if (OldAlign == 0 || NewAlign == 0) {
2543  QualType Ty;
2544  if (ValueDecl *VD = dyn_cast<ValueDecl>(New))
2545  Ty = VD->getType();
2546  else
2547  Ty = S.Context.getTagDeclType(cast<TagDecl>(New));
2548 
2549  if (OldAlign == 0)
2550  OldAlign = S.Context.getTypeAlign(Ty);
2551  if (NewAlign == 0)
2552  NewAlign = S.Context.getTypeAlign(Ty);
2553  }
2554 
2555  if (OldAlign != NewAlign) {
2556  S.Diag(NewAlignasAttr->getLocation(), diag::err_alignas_mismatch)
2558  << (unsigned)S.Context.toCharUnitsFromBits(NewAlign).getQuantity();
2559  S.Diag(OldAlignasAttr->getLocation(), diag::note_previous_declaration);
2560  }
2561  }
2562 
2563  if (OldAlignasAttr && !NewAlignasAttr && isAttributeTargetADefinition(New)) {
2564  // C++11 [dcl.align]p6:
2565  // if any declaration of an entity has an alignment-specifier,
2566  // every defining declaration of that entity shall specify an
2567  // equivalent alignment.
2568  // C11 6.7.5/7:
2569  // If the definition of an object does not have an alignment
2570  // specifier, any other declaration of that object shall also
2571  // have no alignment specifier.
2572  S.Diag(New->getLocation(), diag::err_alignas_missing_on_definition)
2573  << OldAlignasAttr;
2574  S.Diag(OldAlignasAttr->getLocation(), diag::note_alignas_on_declaration)
2575  << OldAlignasAttr;
2576  }
2577 
2578  bool AnyAdded = false;
2579 
2580  // Ensure we have an attribute representing the strictest alignment.
2581  if (OldAlign > NewAlign) {
2582  AlignedAttr *Clone = OldStrictestAlignAttr->clone(S.Context);
2583  Clone->setInherited(true);
2584  New->addAttr(Clone);
2585  AnyAdded = true;
2586  }
2587 
2588  // Ensure we have an alignas attribute if the old declaration had one.
2589  if (OldAlignasAttr && !NewAlignasAttr &&
2590  !(AnyAdded && OldStrictestAlignAttr->isAlignas())) {
2591  AlignedAttr *Clone = OldAlignasAttr->clone(S.Context);
2592  Clone->setInherited(true);
2593  New->addAttr(Clone);
2594  AnyAdded = true;
2595  }
2596 
2597  return AnyAdded;
2598 }
2599 
2600 #define WANT_DECL_MERGE_LOGIC
2601 #include "clang/Sema/AttrParsedAttrImpl.inc"
2602 #undef WANT_DECL_MERGE_LOGIC
2603 
2604 static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
2605  const InheritableAttr *Attr,
2607  // Diagnose any mutual exclusions between the attribute that we want to add
2608  // and attributes that already exist on the declaration.
2609  if (!DiagnoseMutualExclusions(S, D, Attr))
2610  return false;
2611 
2612  // This function copies an attribute Attr from a previous declaration to the
2613  // new declaration D if the new declaration doesn't itself have that attribute
2614  // yet or if that attribute allows duplicates.
2615  // If you're adding a new attribute that requires logic different from
2616  // "use explicit attribute on decl if present, else use attribute from
2617  // previous decl", for example if the attribute needs to be consistent
2618  // between redeclarations, you need to call a custom merge function here.
2619  InheritableAttr *NewAttr = nullptr;
2620  if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
2621  NewAttr = S.mergeAvailabilityAttr(
2622  D, *AA, AA->getPlatform(), AA->isImplicit(), AA->getIntroduced(),
2623  AA->getDeprecated(), AA->getObsoleted(), AA->getUnavailable(),
2624  AA->getMessage(), AA->getStrict(), AA->getReplacement(), AMK,
2625  AA->getPriority());
2626  else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
2627  NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility());
2628  else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr))
2629  NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility());
2630  else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr))
2631  NewAttr = S.mergeDLLImportAttr(D, *ImportA);
2632  else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr))
2633  NewAttr = S.mergeDLLExportAttr(D, *ExportA);
2634  else if (const auto *EA = dyn_cast<ErrorAttr>(Attr))
2635  NewAttr = S.mergeErrorAttr(D, *EA, EA->getUserDiagnostic());
2636  else if (const auto *FA = dyn_cast<FormatAttr>(Attr))
2637  NewAttr = S.mergeFormatAttr(D, *FA, FA->getType(), FA->getFormatIdx(),
2638  FA->getFirstArg());
2639  else if (const auto *SA = dyn_cast<SectionAttr>(Attr))
2640  NewAttr = S.mergeSectionAttr(D, *SA, SA->getName());
2641  else if (const auto *CSA = dyn_cast<CodeSegAttr>(Attr))
2642  NewAttr = S.mergeCodeSegAttr(D, *CSA, CSA->getName());
2643  else if (const auto *IA = dyn_cast<MSInheritanceAttr>(Attr))
2644  NewAttr = S.mergeMSInheritanceAttr(D, *IA, IA->getBestCase(),
2645  IA->getInheritanceModel());
2646  else if (const auto *AA = dyn_cast<AlwaysInlineAttr>(Attr))
2647  NewAttr = S.mergeAlwaysInlineAttr(D, *AA,
2648  &S.Context.Idents.get(AA->getSpelling()));
2649  else if (S.getLangOpts().CUDA && isa<FunctionDecl>(D) &&
2650  (isa<CUDAHostAttr>(Attr) || isa<CUDADeviceAttr>(Attr) ||
2651  isa<CUDAGlobalAttr>(Attr))) {
2652  // CUDA target attributes are part of function signature for
2653  // overloading purposes and must not be merged.
2654  return false;
2655  } else if (const auto *MA = dyn_cast<MinSizeAttr>(Attr))
2656  NewAttr = S.mergeMinSizeAttr(D, *MA);
2657  else if (const auto *SNA = dyn_cast<SwiftNameAttr>(Attr))
2658  NewAttr = S.mergeSwiftNameAttr(D, *SNA, SNA->getName());
2659  else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
2660  NewAttr = S.mergeOptimizeNoneAttr(D, *OA);
2661  else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
2662  NewAttr = S.mergeInternalLinkageAttr(D, *InternalLinkageA);
2663  else if (isa<AlignedAttr>(Attr))
2664  // AlignedAttrs are handled separately, because we need to handle all
2665  // such attributes on a declaration at the same time.
2666  NewAttr = nullptr;
2667  else if ((isa<DeprecatedAttr>(Attr) || isa<UnavailableAttr>(Attr)) &&
2668  (AMK == Sema::AMK_Override ||
2671  NewAttr = nullptr;
2672  else if (const auto *UA = dyn_cast<UuidAttr>(Attr))
2673  NewAttr = S.mergeUuidAttr(D, *UA, UA->getGuid(), UA->getGuidDecl());
2674  else if (const auto *IMA = dyn_cast<WebAssemblyImportModuleAttr>(Attr))
2675  NewAttr = S.mergeImportModuleAttr(D, *IMA);
2676  else if (const auto *INA = dyn_cast<WebAssemblyImportNameAttr>(Attr))
2677  NewAttr = S.mergeImportNameAttr(D, *INA);
2678  else if (const auto *TCBA = dyn_cast<EnforceTCBAttr>(Attr))
2679  NewAttr = S.mergeEnforceTCBAttr(D, *TCBA);
2680  else if (const auto *TCBLA = dyn_cast<EnforceTCBLeafAttr>(Attr))
2681  NewAttr = S.mergeEnforceTCBLeafAttr(D, *TCBLA);
2682  else if (const auto *BTFA = dyn_cast<BTFTagAttr>(Attr))
2683  NewAttr = S.mergeBTFTagAttr(D, *BTFA);
2684  else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
2685  NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
2686 
2687  if (NewAttr) {
2688  NewAttr->setInherited(true);
2689  D->addAttr(NewAttr);
2690  if (isa<MSInheritanceAttr>(NewAttr))
2691  S.Consumer.AssignInheritanceModel(cast<CXXRecordDecl>(D));
2692  return true;
2693  }
2694 
2695  return false;
2696 }
2697 
2698 static const NamedDecl *getDefinition(const Decl *D) {
2699  if (const TagDecl *TD = dyn_cast<TagDecl>(D))
2700  return TD->getDefinition();
2701  if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
2702  const VarDecl *Def = VD->getDefinition();
2703  if (Def)
2704  return Def;
2705  return VD->getActingDefinition();
2706  }
2707  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
2708  const FunctionDecl *Def = nullptr;
2709  if (FD->isDefined(Def, true))
2710  return Def;
2711  }
2712  return nullptr;
2713 }
2714 
2715 static bool hasAttribute(const Decl *D, attr::Kind Kind) {
2716  for (const auto *Attribute : D->attrs())
2717  if (Attribute->getKind() == Kind)
2718  return true;
2719  return false;
2720 }
2721 
2722 /// checkNewAttributesAfterDef - If we already have a definition, check that
2723 /// there are no new attributes in this declaration.
2724 static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
2725  if (!New->hasAttrs())
2726  return;
2727 
2728  const NamedDecl *Def = getDefinition(Old);
2729  if (!Def || Def == New)
2730  return;
2731 
2732  AttrVec &NewAttributes = New->getAttrs();
2733  for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
2734  const Attr *NewAttribute = NewAttributes[I];
2735 
2736  if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
2737  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
2738  Sema::SkipBodyInfo SkipBody;
2739  S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);
2740 
2741  // If we're skipping this definition, drop the "alias" attribute.
2742  if (SkipBody.ShouldSkip) {
2743  NewAttributes.erase(NewAttributes.begin() + I);
2744  --E;
2745  continue;
2746  }
2747  } else {
2748  VarDecl *VD = cast<VarDecl>(New);
2749  unsigned Diag = cast<VarDecl>(Def)->isThisDeclarationADefinition() ==
2751  ? diag::err_alias_after_tentative
2752  : diag::err_redefinition;
2753  S.Diag(VD->getLocation(), Diag) << VD->getDeclName();
2754  if (Diag == diag::err_redefinition)
2755  S.notePreviousDefinition(Def, VD->getLocation());
2756  else
2757  S.Diag(Def->getLocation(), diag::note_previous_definition);
2758  VD->setInvalidDecl();
2759  }
2760  ++I;
2761  continue;
2762  }
2763 
2764  if (const VarDecl *VD = dyn_cast<VarDecl>(Def)) {
2765  // Tentative definitions are only interesting for the alias check above.
2766  if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
2767  ++I;
2768  continue;
2769  }
2770  }
2771 
2772  if (hasAttribute(Def, NewAttribute->getKind())) {
2773  ++I;
2774  continue; // regular attr merging will take care of validating this.
2775  }
2776 
2777  if (isa<C11NoReturnAttr>(NewAttribute)) {
2778  // C's _Noreturn is allowed to be added to a function after it is defined.
2779  ++I;
2780  continue;
2781  } else if (isa<UuidAttr>(NewAttribute)) {
2782  // msvc will allow a subsequent definition to add an uuid to a class
2783  ++I;
2784  continue;
2785  } else if (const AlignedAttr *AA = dyn_cast<AlignedAttr>(NewAttribute)) {
2786  if (AA->isAlignas()) {
2787  // C++11 [dcl.align]p6:
2788  // if any declaration of an entity has an alignment-specifier,
2789  // every defining declaration of that entity shall specify an
2790  // equivalent alignment.
2791  // C11 6.7.5/7:
2792  // If the definition of an object does not have an alignment
2793  // specifier, any other declaration of that object shall also
2794  // have no alignment specifier.
2795  S.Diag(Def->getLocation(), diag::err_alignas_missing_on_definition)
2796  << AA;
2797  S.Diag(NewAttribute->getLocation(), diag::note_alignas_on_declaration)
2798  << AA;
2799  NewAttributes.erase(NewAttributes.begin() + I);
2800  --E;
2801  continue;
2802  }
2803  } else if (isa<LoaderUninitializedAttr>(NewAttribute)) {
2804  // If there is a C definition followed by a redeclaration with this
2805  // attribute then there are two different definitions. In C++, prefer the
2806  // standard diagnostics.
2807  if (!S.getLangOpts().CPlusPlus) {
2808  S.Diag(NewAttribute->getLocation(),
2809  diag::err_loader_uninitialized_redeclaration);
2810  S.Diag(Def->getLocation(), diag::note_previous_definition);
2811  NewAttributes.erase(NewAttributes.begin() + I);
2812  --E;
2813  continue;
2814  }
2815  } else if (isa<SelectAnyAttr>(NewAttribute) &&
2816  cast<VarDecl>(New)->isInline() &&
2817  !cast<VarDecl>(New)->isInlineSpecified()) {
2818  // Don't warn about applying selectany to implicitly inline variables.
2819  // Older compilers and language modes would require the use of selectany
2820  // to make such variables inline, and it would have no effect if we
2821  // honored it.
2822  ++I;
2823  continue;
2824  } else if (isa<OMPDeclareVariantAttr>(NewAttribute)) {
2825  // We allow to add OMP[Begin]DeclareVariantAttr to be added to
2826  // declarations after defintions.
2827  ++I;
2828  continue;
2829  }
2830 
2831  S.Diag(NewAttribute->getLocation(),
2832  diag::warn_attribute_precede_definition);
2833  S.Diag(Def->getLocation(), diag::note_previous_definition);
2834  NewAttributes.erase(NewAttributes.begin() + I);
2835  --E;
2836  }
2837 }
2838 
2839 static void diagnoseMissingConstinit(Sema &S, const VarDecl *InitDecl,
2840  const ConstInitAttr *CIAttr,
2841  bool AttrBeforeInit) {
2842  SourceLocation InsertLoc = InitDecl->getInnerLocStart();
2843 
2844  // Figure out a good way to write this specifier on the old declaration.
2845  // FIXME: We should just use the spelling of CIAttr, but we don't preserve
2846  // enough of the attribute list spelling information to extract that without
2847  // heroics.
2848  std::string SuitableSpelling;
2849  if (S.getLangOpts().CPlusPlus20)
2850  SuitableSpelling = std::string(
2851  S.PP.getLastMacroWithSpelling(InsertLoc, {tok::kw_constinit}));
2852  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
2853  SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
2854  InsertLoc, {tok::l_square, tok::l_square,
2855  S.PP.getIdentifierInfo("clang"), tok::coloncolon,
2856  S.PP.getIdentifierInfo("require_constant_initialization"),
2857  tok::r_square, tok::r_square}));
2858  if (SuitableSpelling.empty())
2859  SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
2860  InsertLoc, {tok::kw___attribute, tok::l_paren, tok::r_paren,
2861  S.PP.getIdentifierInfo("require_constant_initialization"),
2862  tok::r_paren, tok::r_paren}));
2863  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus20)
2864  SuitableSpelling = "constinit";
2865  if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
2866  SuitableSpelling = "[[clang::require_constant_initialization]]";
2867  if (SuitableSpelling.empty())
2868  SuitableSpelling = "__attribute__((require_constant_initialization))";
2869  SuitableSpelling += " ";
2870 
2871  if (AttrBeforeInit) {
2872  // extern constinit int a;
2873  // int a = 0; // error (missing 'constinit'), accepted as extension
2874  assert(CIAttr->isConstinit() && "should not diagnose this for attribute");
2875  S.Diag(InitDecl->getLocation(), diag::ext_constinit_missing)
2876  << InitDecl << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
2877  S.Diag(CIAttr->getLocation(), diag::note_constinit_specified_here);
2878  } else {
2879  // int a = 0;
2880  // constinit extern int a; // error (missing 'constinit')
2881  S.Diag(CIAttr->getLocation(),
2882  CIAttr->isConstinit() ? diag::err_constinit_added_too_late
2883  : diag::warn_require_const_init_added_too_late)
2884  << FixItHint::CreateRemoval(SourceRange(CIAttr->getLocation()));
2885  S.Diag(InitDecl->getLocation(), diag::note_constinit_missing_here)
2886  << CIAttr->isConstinit()
2887  << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
2888  }
2889 }
2890 
2891 /// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
2893  AvailabilityMergeKind AMK) {
2894  if (UsedAttr *OldAttr = Old->getMostRecentDecl()->getAttr<UsedAttr>()) {
2895  UsedAttr *NewAttr = OldAttr->clone(Context);
2896  NewAttr->setInherited(true);
2897  New->addAttr(NewAttr);
2898  }
2899  if (RetainAttr *OldAttr = Old->getMostRecentDecl()->getAttr<RetainAttr>()) {
2900  RetainAttr *NewAttr = OldAttr->clone(Context);
2901  NewAttr->setInherited(true);
2902  New->addAttr(NewAttr);
2903  }
2904 
2905  if (!Old->hasAttrs() && !New->hasAttrs())
2906  return;
2907 
2908  // [dcl.constinit]p1:
2909  // If the [constinit] specifier is applied to any declaration of a
2910  // variable, it shall be applied to the initializing declaration.
2911  const auto *OldConstInit = Old->getAttr<ConstInitAttr>();
2912  const auto *NewConstInit = New->getAttr<ConstInitAttr>();
2913  if (bool(OldConstInit) != bool(NewConstInit)) {
2914  const auto *OldVD = cast<VarDecl>(Old);
2915  auto *NewVD = cast<VarDecl>(New);
2916 
2917  // Find the initializing declaration. Note that we might not have linked
2918  // the new declaration into the redeclaration chain yet.
2919  const VarDecl *InitDecl = OldVD->getInitializingDeclaration();
2920  if (!InitDecl &&
2921  (NewVD->hasInit() || NewVD->isThisDeclarationADefinition()))
2922  InitDecl = NewVD;
2923 
2924  if (InitDecl == NewVD) {
2925  // This is the initializing declaration. If it would inherit 'constinit',
2926  // that's ill-formed. (Note that we do not apply this to the attribute
2927  // form).
2928  if (OldConstInit && OldConstInit->isConstinit())
2929  diagnoseMissingConstinit(*this, NewVD, OldConstInit,
2930  /*AttrBeforeInit=*/true);
2931  } else if (NewConstInit) {
2932  // This is the first time we've been told that this declaration should
2933  // have a constant initializer. If we already saw the initializing
2934  // declaration, this is too late.
2935  if (InitDecl && InitDecl != NewVD) {
2936  diagnoseMissingConstinit(*this, InitDecl, NewConstInit,
2937  /*AttrBeforeInit=*/false);
2938  NewVD->dropAttr<ConstInitAttr>();
2939  }
2940  }
2941  }
2942 
2943  // Attributes declared post-definition are currently ignored.
2944  checkNewAttributesAfterDef(*this, New, Old);
2945 
2946  if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
2947  if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
2948  if (!OldA->isEquivalent(NewA)) {
2949  // This redeclaration changes __asm__ label.
2950  Diag(New->getLocation(), diag::err_different_asm_label);
2951  Diag(OldA->getLocation(), diag::note_previous_declaration);
2952  }
2953  } else if (Old->isUsed()) {
2954  // This redeclaration adds an __asm__ label to a declaration that has
2955  // already been ODR-used.
2956  Diag(New->getLocation(), diag::err_late_asm_label_name)
2957  << isa<FunctionDecl>(Old) << New->getAttr<AsmLabelAttr>()->getRange();
2958  }
2959  }
2960 
2961  // Re-declaration cannot add abi_tag's.
2962  if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) {
2963  if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) {
2964  for (const auto &NewTag : NewAbiTagAttr->tags()) {
2965  if (std::find(OldAbiTagAttr->tags_begin(), OldAbiTagAttr->tags_end(),
2966  NewTag) == OldAbiTagAttr->tags_end()) {
2967  Diag(NewAbiTagAttr->getLocation(),
2968  diag::err_new_abi_tag_on_redeclaration)
2969  << NewTag;
2970  Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration);
2971  }
2972  }
2973  } else {
2974  Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration);
2975  Diag(Old->getLocation(), diag::note_previous_declaration);
2976  }
2977  }
2978 
2979  // This redeclaration adds a section attribute.
2980  if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
2981  if (auto *VD = dyn_cast<VarDecl>(New)) {
2982  if (VD->isThisDeclarationADefinition() == VarDecl::DeclarationOnly) {
2983  Diag(New->getLocation(), diag::warn_attribute_section_on_redeclaration);
2984  Diag(Old->getLocation(), diag::note_previous_declaration);
2985  }
2986  }
2987  }
2988 
2989  // Redeclaration adds code-seg attribute.
2990  const auto *NewCSA = New->getAttr<CodeSegAttr>();
2991  if (NewCSA && !Old->hasAttr<CodeSegAttr>() &&
2992  !NewCSA->isImplicit() && isa<CXXMethodDecl>(New)) {
2993  Diag(New->getLocation(), diag::warn_mismatched_section)
2994  << 0 /*codeseg*/;
2995  Diag(Old->getLocation(), diag::note_previous_declaration);
2996  }
2997 
2998  if (!Old->hasAttrs())
2999  return;
3000 
3001  bool foundAny = New->hasAttrs();
3002 
3003  // Ensure that any moving of objects within the allocated map is done before
3004  // we process them.
3005  if (!foundAny) New->setAttrs(AttrVec());
3006 
3007  for (auto *I : Old->specific_attrs<InheritableAttr>()) {
3008  // Ignore deprecated/unavailable/availability attributes if requested.
3009  AvailabilityMergeKind LocalAMK = AMK_None;
3010  if (isa<DeprecatedAttr>(I) ||
3011  isa<UnavailableAttr>(I) ||
3012  isa<AvailabilityAttr>(I)) {
3013  switch (AMK) {
3014  case AMK_None:
3015  continue;
3016 
3017  case AMK_Redeclaration:
3018  case AMK_Override:
3019  case AMK_ProtocolImplementation:
3020  case AMK_OptionalProtocolImplementation:
3021  LocalAMK = AMK;
3022  break;
3023  }
3024  }
3025 
3026  // Already handled.
3027  if (isa<UsedAttr>(I) || isa<RetainAttr>(I))
3028  continue;
3029 
3030  if (mergeDeclAttribute(*this, New, I, LocalAMK))
3031  foundAny = true;
3032  }
3033 
3034  if (mergeAlignedAttrs(*this, New, Old))
3035  foundAny = true;
3036 
3037  if (!foundAny) New->dropAttrs();
3038 }
3039 
3040 /// mergeParamDeclAttributes - Copy attributes from the old parameter
3041 /// to the new one.
3043  const ParmVarDecl *oldDecl,
3044  Sema &S) {
3045  // C++11 [dcl.attr.depend]p2:
3046  // The first declaration of a function shall specify the
3047  // carries_dependency attribute for its declarator-id if any declaration
3048  // of the function specifies the carries_dependency attribute.
3049  const CarriesDependencyAttr *CDA = newDecl->getAttr<CarriesDependencyAttr>();
3050  if (CDA && !oldDecl->hasAttr<CarriesDependencyAttr>()) {
3051  S.Diag(CDA->getLocation(),
3052  diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
3053  // Find the first declaration of the parameter.
3054  // FIXME: Should we build redeclaration chains for function parameters?
3055  const FunctionDecl *FirstFD =
3056  cast<FunctionDecl>(oldDecl->getDeclContext())->getFirstDecl();
3057  const ParmVarDecl *FirstVD =
3058  FirstFD->getParamDecl(oldDecl->getFunctionScopeIndex());
3059  S.Diag(FirstVD->getLocation(),
3060  diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
3061  }
3062 
3063  if (!oldDecl->hasAttrs())
3064  return;
3065 
3066  bool foundAny = newDecl->hasAttrs();
3067 
3068  // Ensure that any moving of objects within the allocated map is
3069  // done before we process them.
3070  if (!foundAny) newDecl->setAttrs(AttrVec());
3071 
3072  for (const auto *I : oldDecl->specific_attrs<InheritableParamAttr>()) {
3073  if (!DeclHasAttr(newDecl, I)) {
3074  InheritableAttr *newAttr =
3075  cast<InheritableParamAttr>(I->clone(S.Context));
3076  newAttr->setInherited(true);
3077  newDecl->addAttr(newAttr);
3078  foundAny = true;
3079  }
3080  }
3081 
3082  if (!foundAny) newDecl->dropAttrs();
3083 }
3084 
3085 static void mergeParamDeclTypes(ParmVarDecl *NewParam,
3086  const ParmVarDecl *OldParam,
3087  Sema &S) {
3088  if (auto Oldnullability = OldParam->getType()->getNullability(S.Context)) {
3089  if (auto Newnullability = NewParam->getType()->getNullability(S.Context)) {
3090  if (*Oldnullability != *Newnullability) {
3091  S.Diag(NewParam->getLocation(), diag::warn_mismatched_nullability_attr)
3093  *Newnullability,
3095  != 0))
3097  *Oldnullability,
3099  != 0));
3100  S.Diag(OldParam->getLocation(), diag::note_previous_declaration);
3101  }
3102  } else {
3103  QualType NewT = NewParam->getType();
3104  NewT = S.Context.getAttributedType(
3105  AttributedType::getNullabilityAttrKind(*Oldnullability),
3106  NewT, NewT);
3107  NewParam->setType(NewT);
3108  }
3109  }
3110 }
3111 
3112 namespace {
3113 
3114 /// Used in MergeFunctionDecl to keep track of function parameters in
3115 /// C.
3116 struct GNUCompatibleParamWarning {
3117  ParmVarDecl *OldParm;
3118  ParmVarDecl *NewParm;
3119  QualType PromotedType;
3120 };
3121 
3122 } // end anonymous namespace
3123 
3124 // Determine whether the previous declaration was a definition, implicit
3125 // declaration, or a declaration.
3126 template <typename T>
3127 static std::pair<diag::kind, SourceLocation>
3128 getNoteDiagForInvalidRedeclaration(const T *Old, const T *New) {
3129  diag::kind PrevDiag;
3130  SourceLocation OldLocation = Old->getLocation();
3131  if (Old->isThisDeclarationADefinition())
3132  PrevDiag = diag::note_previous_definition;
3133  else if (Old->isImplicit()) {
3134  PrevDiag = diag::note_previous_implicit_declaration;
3135  if (OldLocation.isInvalid())
3136  OldLocation = New->getLocation();
3137  } else
3138  PrevDiag = diag::note_previous_declaration;
3139  return std::make_pair(PrevDiag, OldLocation);
3140 }
3141 
3142 /// canRedefineFunction - checks if a function can be redefined. Currently,
3143 /// only extern inline functions can be redefined, and even then only in
3144 /// GNU89 mode.
3145 static bool canRedefineFunction(const FunctionDecl *FD,
3146  const LangOptions& LangOpts) {
3147  return ((FD->hasAttr<GNUInlineAttr>() || LangOpts.GNUInline) &&
3148  !LangOpts.CPlusPlus &&
3149  FD->isInlineSpecified() &&
3150  FD->getStorageClass() == SC_Extern);
3151 }
3152 
3154  const AttributedType *AT = T->getAs<AttributedType>();
3155  while (AT && !AT->isCallingConv())
3156  AT = AT->getModifiedType()->getAs<AttributedType>();
3157  return AT;
3158 }
3159 
3160 template <typename T>
3161 static bool haveIncompatibleLanguageLinkages(const T *Old, const T *New) {
3162  const DeclContext *DC = Old->getDeclContext();
3163  if (DC->isRecord())
3164  return false;
3165 
3166  LanguageLinkage OldLinkage = Old->getLanguageLinkage();
3167  if (OldLinkage == CXXLanguageLinkage && New->isInExternCContext())
3168  return true;
3169  if (OldLinkage == CLanguageLinkage && New->isInExternCXXContext())
3170  return true;
3171  return false;
3172 }
3173 
3174 template<typename T> static bool isExternC(T *D) { return D->isExternC(); }
3175 static bool isExternC(VarTemplateDecl *) { return false; }
3176 static bool isExternC(FunctionTemplateDecl *) { return false; }
3177 
3178 /// Check whether a redeclaration of an entity introduced by a
3179 /// using-declaration is valid, given that we know it's not an overload
3180 /// (nor a hidden tag declaration).
3181 template<typename ExpectedDecl>
3183  ExpectedDecl *New) {
3184  // C++11 [basic.scope.declarative]p4:
3185  // Given a set of declarations in a single declarative region, each of
3186  // which specifies the same unqualified name,
3187  // -- they shall all refer to the same entity, or all refer to functions
3188  // and function templates; or
3189  // -- exactly one declaration shall declare a class name or enumeration
3190  // name that is not a typedef name and the other declarations shall all
3191  // refer to the same variable or enumerator, or all refer to functions
3192  // and function templates; in this case the class name or enumeration
3193  // name is hidden (3.3.10).
3194 
3195  // C++11 [namespace.udecl]p14:
3196  // If a function declaration in namespace scope or block scope has the
3197  // same name and the same parameter-type-list as a function introduced
3198  // by a using-declaration, and the declarations do not declare the same
3199  // function, the program is ill-formed.
3200 
3201  auto *Old = dyn_cast<ExpectedDecl>(OldS->getTargetDecl());
3202  if (Old &&
3203  !Old->getDeclContext()->getRedeclContext()->Equals(
3204  New->getDeclContext()->getRedeclContext()) &&
3205  !(isExternC(Old) && isExternC(New)))
3206  Old = nullptr;
3207 
3208  if (!Old) {
3209  S.Diag(New->getLocation(), diag::err_using_decl_conflict_reverse);
3210  S.Diag(OldS->getTargetDecl()->getLocation(), diag::note_using_decl_target);
3211  S.Diag(OldS->getIntroducer()->getLocation(), diag::note_using_decl) << 0;
3212  return true;
3213  }
3214  return false;
3215 }
3216 
3218  const FunctionDecl *B) {
3219  assert(A->getNumParams() == B->getNumParams());
3220 
3221  auto AttrEq = [](const ParmVarDecl *A, const ParmVarDecl *B) {
3222  const auto *AttrA = A->getAttr<PassObjectSizeAttr>();
3223  const auto *AttrB = B->getAttr<PassObjectSizeAttr>();
3224  if (AttrA == AttrB)
3225  return true;
3226  return AttrA && AttrB && AttrA->getType() == AttrB->getType() &&
3227  AttrA->isDynamic() == AttrB->isDynamic();
3228  };
3229 
3230  return std::equal(A->param_begin(), A->param_end(), B->param_begin(), AttrEq);
3231 }
3232 
3233 /// If necessary, adjust the semantic declaration context for a qualified
3234 /// declaration to name the correct inline namespace within the qualifier.
3236  DeclaratorDecl *OldD) {
3237  // The only case where we need to update the DeclContext is when
3238  // redeclaration lookup for a qualified name finds a declaration
3239  // in an inline namespace within the context named by the qualifier:
3240  //
3241  // inline namespace N { int f(); }
3242  // int ::f(); // Sema DC needs adjusting from :: to N::.
3243  //
3244  // For unqualified declarations, the semantic context *can* change
3245  // along the redeclaration chain (for local extern declarations,
3246  // extern "C" declarations, and friend declarations in particular).
3247  if (!NewD->getQualifier())
3248  return;
3249 
3250  // NewD is probably already in the right context.
3251  auto *NamedDC = NewD->getDeclContext()->getRedeclContext();
3252  auto *SemaDC = OldD->getDeclContext()->getRedeclContext();
3253  if (NamedDC->Equals(SemaDC))
3254  return;
3255 
3256  assert((NamedDC->InEnclosingNamespaceSetOf(SemaDC) ||
3257  NewD->isInvalidDecl() || OldD->isInvalidDecl()) &&
3258  "unexpected context for redeclaration");
3259 
3260  auto *LexDC = NewD->getLexicalDeclContext();
3261  auto FixSemaDC = [=](NamedDecl *D) {
3262  if (!D)
3263  return;
3264  D->setDeclContext(SemaDC);
3265  D->setLexicalDeclContext(LexDC);
3266  };
3267 
3268  FixSemaDC(NewD);
3269  if (auto *FD = dyn_cast<FunctionDecl>(NewD))
3270  FixSemaDC(FD->getDescribedFunctionTemplate());
3271  else if (auto *VD = dyn_cast<VarDecl>(NewD))
3272  FixSemaDC(VD->getDescribedVarTemplate());
3273 }
3274 
3275 /// MergeFunctionDecl - We just parsed a function 'New' from
3276 /// declarator D which has the same name and scope as a previous
3277 /// declaration 'Old'. Figure out how to resolve this situation,
3278 /// merging decls or emitting diagnostics as appropriate.
3279 ///
3280 /// In C++, New and Old must be declarations that are not
3281 /// overloaded. Use IsOverload to determine whether New and Old are
3282 /// overloaded, and to select the Old declaration that New should be
3283 /// merged with.
3284 ///
3285 /// Returns true if there was an error, false otherwise.
3287  Scope *S, bool MergeTypeWithOld) {
3288  // Verify the old decl was also a function.
3289  FunctionDecl *Old = OldD->getAsFunction();
3290  if (!Old) {
3291  if (UsingShadowDecl *Shadow = dyn_cast<UsingShadowDecl>(OldD)) {
3292  if (New->getFriendObjectKind()) {
3293  Diag(New->getLocation(), diag::err_using_decl_friend);
3294  Diag(Shadow->getTargetDecl()->getLocation(),
3295  diag::note_using_decl_target);
3296  Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl)
3297  << 0;
3298  return true;
3299  }
3300 
3301  // Check whether the two declarations might declare the same function or
3302  // function template.
3303  if (FunctionTemplateDecl *NewTemplate =
3305  if (checkUsingShadowRedecl<FunctionTemplateDecl>(*this, Shadow,
3306  NewTemplate))
3307  return true;
3308  OldD = Old = cast<FunctionTemplateDecl>(Shadow->getTargetDecl())
3309  ->getAsFunction();
3310  } else {
3311  if (checkUsingShadowRedecl<FunctionDecl>(*this, Shadow, New))
3312  return true;
3313  OldD = Old = cast<FunctionDecl>(Shadow->getTargetDecl());
3314  }
3315  } else {
3316  Diag(New->getLocation(), diag::err_redefinition_different_kind)
3317  << New->getDeclName();
3318  notePreviousDefinition(OldD, New->getLocation());
3319  return true;
3320  }
3321  }
3322 
3323  // If the old declaration was found in an inline namespace and the new
3324  // declaration was qualified, update the DeclContext to match.
3326 
3327  // If the old declaration is invalid, just give up here.
3328  if (Old->isInvalidDecl())
3329  return true;
3330 
3331  // Disallow redeclaration of some builtins.
3332  if (!getASTContext().canBuiltinBeRedeclared(Old)) {
3333  Diag(New->getLocation(), diag::err_builtin_redeclare) << Old->getDeclName();
3334  Diag(Old->getLocation(), diag::note_previous_builtin_declaration)
3335  << Old << Old->getType();
3336  return true;
3337  }
3338 
3339  diag::kind PrevDiag;
3340  SourceLocation OldLocation;
3341  std::tie(PrevDiag, OldLocation) =
3343 
3344  // Don't complain about this if we're in GNU89 mode and the old function
3345  // is an extern inline function.
3346  // Don't complain about specializations. They are not supposed to have
3347  // storage classes.
3348  if (!isa<CXXMethodDecl>(New) && !isa<CXXMethodDecl>(Old) &&
3349  New->getStorageClass() == SC_Static &&
3350  Old->hasExternalFormalLinkage() &&
3352  !canRedefineFunction(Old, getLangOpts())) {
3353  if (getLangOpts().MicrosoftExt) {
3354  Diag(New->getLocation(), diag::ext_static_non_static) << New;
3355  Diag(OldLocation, PrevDiag);
3356  } else {
3357  Diag(New->getLocation(), diag::err_static_non_static) << New;
3358  Diag(OldLocation, PrevDiag);
3359  return true;
3360  }
3361  }
3362 
3363  if (const auto *ILA = New->getAttr<InternalLinkageAttr>())
3364  if (!Old->hasAttr<InternalLinkageAttr>()) {
3365  Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
3366  << ILA;
3367  Diag(Old->getLocation(), diag::note_previous_declaration);
3368  New->dropAttr<InternalLinkageAttr>();
3369  }
3370 
3371  if (auto *EA = New->getAttr<ErrorAttr>()) {
3372  if (!Old->hasAttr<ErrorAttr>()) {
3373  Diag(EA->getLocation(), diag::err_attribute_missing_on_first_decl) << EA;
3374  Diag(Old->getLocation(), diag::note_previous_declaration);
3375  New->dropAttr<ErrorAttr>();
3376  }
3377  }
3378 
3379  if (CheckRedeclarationModuleOwnership(New, Old))
3380  return true;
3381 
3382  if (!getLangOpts().CPlusPlus) {
3383  bool OldOvl = Old->hasAttr<OverloadableAttr>();
3384  if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) {
3385  Diag(New->getLocation(), diag::err_attribute_overloadable_mismatch)
3386  << New << OldOvl;
3387 
3388  // Try our best to find a decl that actually has the overloadable
3389  // attribute for the note. In most cases (e.g. programs with only one
3390  // broken declaration/definition), this won't matter.
3391  //
3392  // FIXME: We could do this if we juggled some extra state in
3393  // OverloadableAttr, rather than just removing it.
3394  const Decl *DiagOld = Old;
3395  if (OldOvl) {
3396  auto OldIter = llvm::find_if(Old->redecls(), [](const Decl *D) {
3397  const auto *A = D->getAttr<OverloadableAttr>();
3398  return A && !A->isImplicit();
3399  });
3400  // If we've implicitly added *all* of the overloadable attrs to this
3401  // chain, emitting a "previous redecl" note is pointless.
3402  DiagOld = OldIter == Old->redecls_end() ? nullptr : *OldIter;
3403  }
3404 
3405  if (DiagOld)
3406  Diag(DiagOld->getLocation(),
3407  diag::note_attribute_overloadable_prev_overload)
3408  << OldOvl;
3409 
3410  if (OldOvl)
3411  New->addAttr(OverloadableAttr::CreateImplicit(Context));
3412  else
3413  New->dropAttr<OverloadableAttr>();
3414  }
3415  }
3416 
3417  // If a function is first declared with a calling convention, but is later
3418  // declared or defined without one, all following decls assume the calling
3419  // convention of the first.
3420  //
3421  // It's OK if a function is first declared without a calling convention,
3422  // but is later declared or defined with the default calling convention.
3423  //
3424  // To test if either decl has an explicit calling convention, we look for
3425  // AttributedType sugar nodes on the type as written. If they are missing or
3426  // were canonicalized away, we assume the calling convention was implicit.
3427  //
3428  // Note also that we DO NOT return at this point, because we still have
3429  // other tests to run.
3430  QualType OldQType = Context.getCanonicalType(Old->getType());
3431  QualType NewQType = Context.getCanonicalType(New->getType());
3432  const FunctionType *OldType = cast<FunctionType>(OldQType);
3433  const FunctionType *NewType = cast<FunctionType>(NewQType);
3434  FunctionType::ExtInfo OldTypeInfo = OldType->getExtInfo();
3435  FunctionType::ExtInfo NewTypeInfo = NewType->getExtInfo();
3436  bool RequiresAdjustment = false;
3437 
3438  if (OldTypeInfo.getCC() != NewTypeInfo.getCC()) {
3439  FunctionDecl *First = Old->getFirstDecl();
3440  const FunctionType *FT =
3441  First->getType().getCanonicalType()->castAs<FunctionType>();
3442  FunctionType::ExtInfo FI = FT->getExtInfo();
3443  bool NewCCExplicit = getCallingConvAttributedType(New->getType());
3444  if (!NewCCExplicit) {
3445  // Inherit the CC from the previous declaration if it was specified
3446  // there but not here.
3447  NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
3448  RequiresAdjustment = true;
3449  } else if (Old->getBuiltinID()) {
3450  // Builtin attribute isn't propagated to the new one yet at this point,
3451  // so we check if the old one is a builtin.
3452 
3453  // Calling Conventions on a Builtin aren't really useful and setting a
3454  // default calling convention and cdecl'ing some builtin redeclarations is
3455  // common, so warn and ignore the calling convention on the redeclaration.
3456  Diag(New->getLocation(), diag::warn_cconv_unsupported)
3457  << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
3458  << (int)CallingConventionIgnoredReason::BuiltinFunction;
3459  NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
3460  RequiresAdjustment = true;
3461  } else {
3462  // Calling conventions aren't compatible, so complain.
3463  bool FirstCCExplicit = getCallingConvAttributedType(First->getType());
3464  Diag(New->getLocation(), diag::err_cconv_change)
3465  << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
3466  << !FirstCCExplicit
3467  << (!FirstCCExplicit ? "" :
3468  FunctionType::getNameForCallConv(FI.getCC()));
3469 
3470  // Put the note on the first decl, since it is the one that matters.
3471  Diag(First->getLocation(), diag::note_previous_declaration);
3472  return true;
3473  }
3474  }
3475 
3476  // FIXME: diagnose the other way around?
3477  if (OldTypeInfo.getNoReturn() && !NewTypeInfo.getNoReturn()) {
3478  NewTypeInfo = NewTypeInfo.withNoReturn(true);
3479  RequiresAdjustment = true;
3480  }
3481 
3482  // Merge regparm attribute.
3483  if (OldTypeInfo.getHasRegParm() != NewTypeInfo.getHasRegParm() ||
3484  OldTypeInfo.getRegParm() != NewTypeInfo.getRegParm()) {
3485  if (NewTypeInfo.getHasRegParm()) {
3486  Diag(New->getLocation(), diag::err_regparm_mismatch)
3487  << NewType->getRegParmType()
3488  << OldType->getRegParmType();
3489  Diag(OldLocation, diag::note_previous_declaration);
3490  return true;
3491  }
3492 
3493  NewTypeInfo = NewTypeInfo.withRegParm(OldTypeInfo.getRegParm());
3494  RequiresAdjustment = true;
3495  }
3496 
3497  // Merge ns_returns_retained attribute.
3498  if (OldTypeInfo.getProducesResult() != NewTypeInfo.getProducesResult()) {
3499  if (NewTypeInfo.getProducesResult()) {
3500  Diag(New->getLocation(), diag::err_function_attribute_mismatch)
3501  << "'ns_returns_retained'";
3502  Diag(OldLocation, diag::note_previous_declaration);
3503  return true;
3504  }
3505 
3506  NewTypeInfo = NewTypeInfo.withProducesResult(true);
3507  RequiresAdjustment = true;
3508  }
3509 
3510  if (OldTypeInfo.getNoCallerSavedRegs() !=
3511  NewTypeInfo.getNoCallerSavedRegs()) {
3512  if (NewTypeInfo.getNoCallerSavedRegs()) {
3513  AnyX86NoCallerSavedRegistersAttr *Attr =
3514  New->getAttr<AnyX86NoCallerSavedRegistersAttr>();
3515  Diag(New->getLocation(), diag::err_function_attribute_mismatch) << Attr;
3516  Diag(OldLocation, diag::note_previous_declaration);
3517  return true;
3518  }
3519 
3520  NewTypeInfo = NewTypeInfo.withNoCallerSavedRegs(true);
3521  RequiresAdjustment = true;
3522  }
3523 
3524  if (RequiresAdjustment) {
3525  const FunctionType *AdjustedType = New->getType()->getAs<FunctionType>();
3526  AdjustedType = Context.adjustFunctionType(AdjustedType, NewTypeInfo);
3527  New->setType(QualType(AdjustedType, 0));
3528  NewQType = Context.getCanonicalType(New->getType());
3529  }
3530 
3531  // If this redeclaration makes the function inline, we may need to add it to
3532  // UndefinedButUsed.
3533  if (!Old->isInlined() && New->isInlined() &&
3534  !New->hasAttr<GNUInlineAttr>() &&
3535  !getLangOpts().GNUInline &&
3536  Old->isUsed(false) &&
3537  !Old->isDefined() && !New->isThisDeclarationADefinition())
3538  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
3539  SourceLocation()));
3540 
3541  // If this redeclaration makes it newly gnu_inline, we don't want to warn
3542  // about it.
3543  if (New->hasAttr<GNUInlineAttr>() &&
3544  Old->isInlined() && !Old->hasAttr<GNUInlineAttr>()) {
3545  UndefinedButUsed.erase(Old->getCanonicalDecl());
3546  }
3547 
3548  // If pass_object_size params don't match up perfectly, this isn't a valid
3549  // redeclaration.
3550  if (Old->getNumParams() > 0 && Old->getNumParams() == New->getNumParams() &&
3551  !hasIdenticalPassObjectSizeAttrs(Old, New)) {
3552  Diag(New->getLocation(), diag::err_different_pass_object_size_params)
3553  << New->getDeclName();
3554  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3555  return true;
3556  }
3557 
3558  if (getLangOpts().CPlusPlus) {
3559  // C++1z [over.load]p2
3560  // Certain function declarations cannot be overloaded:
3561  // -- Function declarations that differ only in the return type,
3562  // the exception specification, or both cannot be overloaded.
3563 
3564  // Check the exception specifications match. This may recompute the type of
3565  // both Old and New if it resolved exception specifications, so grab the
3566  // types again after this. Because this updates the type, we do this before
3567  // any of the other checks below, which may update the "de facto" NewQType
3568  // but do not necessarily update the type of New.
3569  if (CheckEquivalentExceptionSpec(Old, New))
3570  return true;
3571  OldQType = Context.getCanonicalType(Old->getType());
3572  NewQType = Context.getCanonicalType(New->getType());
3573 
3574  // Go back to the type source info to compare the declared return types,
3575  // per C++1y [dcl.type.auto]p13:
3576  // Redeclarations or specializations of a function or function template
3577  // with a declared return type that uses a placeholder type shall also
3578  // use that placeholder, not a deduced type.
3579  QualType OldDeclaredReturnType = Old->getDeclaredReturnType();
3580  QualType NewDeclaredReturnType = New->getDeclaredReturnType();
3581  if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
3582  canFullyTypeCheckRedeclaration(New, Old, NewDeclaredReturnType,
3583  OldDeclaredReturnType)) {
3584  QualType ResQT;
3585  if (NewDeclaredReturnType->isObjCObjectPointerType() &&
3586  OldDeclaredReturnType->isObjCObjectPointerType())
3587  // FIXME: This does the wrong thing for a deduced return type.
3588  ResQT = Context.mergeObjCGCQualifiers(NewQType, OldQType);
3589  if (ResQT.isNull()) {
3590  if (New->isCXXClassMember() && New->isOutOfLine())
3591  Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type)
3592  << New << New->getReturnTypeSourceRange();
3593  else
3594  Diag(New->getLocation(), diag::err_ovl_diff_return_type)
3595  << New->getReturnTypeSourceRange();
3596  Diag(OldLocation, PrevDiag) << Old << Old->getType()
3597  << Old->getReturnTypeSourceRange();
3598  return true;
3599  }
3600  else
3601  NewQType = ResQT;
3602  }
3603 
3604  QualType OldReturnType = OldType->getReturnType();
3605  QualType NewReturnType = cast<FunctionType>(NewQType)->getReturnType();
3606  if (OldReturnType != NewReturnType) {
3607  // If this function has a deduced return type and has already been
3608  // defined, copy the deduced value from the old declaration.
3609  AutoType *OldAT = Old->getReturnType()->getContainedAutoType();
3610  if (OldAT && OldAT->isDeduced()) {
3611  New->setType(
3612  SubstAutoType(New->getType(),
3613  OldAT->isDependentType() ? Context.DependentTy
3614  : OldAT->getDeducedType()));
3615  NewQType = Context.getCanonicalType(
3616  SubstAutoType(NewQType,
3617  OldAT->isDependentType() ? Context.DependentTy
3618  : OldAT->getDeducedType()));
3619  }
3620  }
3621 
3622  const CXXMethodDecl *OldMethod = dyn_cast<CXXMethodDecl>(Old);
3623  CXXMethodDecl *NewMethod = dyn_cast<CXXMethodDecl>(New);
3624  if (OldMethod && NewMethod) {
3625  // Preserve triviality.
3626  NewMethod->setTrivial(OldMethod->isTrivial());
3627 
3628  // MSVC allows explicit template specialization at class scope:
3629  // 2 CXXMethodDecls referring to the same function will be injected.
3630  // We don't want a redeclaration error.
3631  bool IsClassScopeExplicitSpecialization =
3632  OldMethod->isFunctionTemplateSpecialization() &&
3633  NewMethod->isFunctionTemplateSpecialization();
3634  bool isFriend = NewMethod->getFriendObjectKind();
3635 
3636  if (!isFriend && NewMethod->getLexicalDeclContext()->isRecord() &&
3637  !IsClassScopeExplicitSpecialization) {
3638  // -- Member function declarations with the same name and the
3639  // same parameter types cannot be overloaded if any of them
3640  // is a static member function declaration.
3641  if (OldMethod->isStatic() != NewMethod->isStatic()) {
3642  Diag(New->getLocation(), diag::err_ovl_static_nonstatic_member);
3643  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3644  return true;
3645  }
3646 
3647  // C++ [class.mem]p1:
3648  // [...] A member shall not be declared twice in the
3649  // member-specification, except that a nested class or member
3650  // class template can be declared and then later defined.
3651  if (!inTemplateInstantiation()) {
3652  unsigned NewDiag;
3653  if (isa<CXXConstructorDecl>(OldMethod))
3654  NewDiag = diag::err_constructor_redeclared;
3655  else if (isa<CXXDestructorDecl>(NewMethod))
3656  NewDiag = diag::err_destructor_redeclared;
3657  else if (isa<CXXConversionDecl>(NewMethod))
3658  NewDiag = diag::err_conv_function_redeclared;
3659  else
3660  NewDiag = diag::err_member_redeclared;
3661 
3662  Diag(New->getLocation(), NewDiag);
3663  } else {
3664  Diag(New->getLocation(), diag::err_member_redeclared_in_instantiation)
3665  << New << New->getType();
3666  }
3667  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3668  return true;
3669 
3670  // Complain if this is an explicit declaration of a special
3671  // member that was initially declared implicitly.
3672  //
3673  // As an exception, it's okay to befriend such methods in order
3674  // to permit the implicit constructor/destructor/operator calls.
3675  } else if (OldMethod->isImplicit()) {
3676  if (isFriend) {
3677  NewMethod->setImplicit();
3678  } else {
3679  Diag(NewMethod->getLocation(),
3680  diag::err_definition_of_implicitly_declared_member)
3681  << New << getSpecialMember(OldMethod);
3682  return true;
3683  }
3684  } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
3685  Diag(NewMethod->getLocation(),
3686  diag::err_definition_of_explicitly_defaulted_member)
3687  << getSpecialMember(OldMethod);
3688  return true;
3689  }
3690  }
3691 
3692  // C++11 [dcl.attr.noreturn]p1:
3693  // The first declaration of a function shall specify the noreturn
3694  // attribute if any declaration of that function specifies the noreturn
3695  // attribute.
3696  if (const auto *NRA = New->getAttr<CXX11NoReturnAttr>())
3697  if (!Old->hasAttr<CXX11NoReturnAttr>()) {
3698  Diag(NRA->getLocation(), diag::err_attribute_missing_on_first_decl)
3699  << NRA;
3700  Diag(Old->getLocation(), diag::note_previous_declaration);
3701  }
3702 
3703  // C++11 [dcl.attr.depend]p2:
3704  // The first declaration of a function shall specify the
3705  // carries_dependency attribute for its declarator-id if any declaration
3706  // of the function specifies the carries_dependency attribute.
3707  const CarriesDependencyAttr *CDA = New->getAttr<CarriesDependencyAttr>();
3708  if (CDA && !Old->hasAttr<CarriesDependencyAttr>()) {
3709  Diag(CDA->getLocation(),
3710  diag::err_carries_dependency_missing_on_first_decl) << 0/*Function*/;
3711  Diag(Old->getFirstDecl()->getLocation(),
3712  diag::note_carries_dependency_missing_first_decl) << 0/*Function*/;
3713  }
3714 
3715  // (C++98 8.3.5p3):
3716  // All declarations for a function shall agree exactly in both the
3717  // return type and the parameter-type-list.
3718  // We also want to respect all the extended bits except noreturn.
3719 
3720  // noreturn should now match unless the old type info didn't have it.
3721  QualType OldQTypeForComparison = OldQType;
3722  if (!OldTypeInfo.getNoReturn() && NewTypeInfo.getNoReturn()) {
3723  auto *OldType = OldQType->castAs<FunctionProtoType>();
3724  const FunctionType *OldTypeForComparison
3725  = Context.adjustFunctionType(OldType, OldTypeInfo.withNoReturn(true));
3726  OldQTypeForComparison = QualType(OldTypeForComparison, 0);
3727  assert(OldQTypeForComparison.isCanonical());
3728  }
3729 
3730  if (haveIncompatibleLanguageLinkages(Old, New)) {
3731  // As a special case, retain the language linkage from previous
3732  // declarations of a friend function as an extension.
3733  //
3734  // This liberal interpretation of C++ [class.friend]p3 matches GCC/MSVC
3735  // and is useful because there's otherwise no way to specify language
3736  // linkage within class scope.
3737  //
3738  // Check cautiously as the friend object kind isn't yet complete.
3739  if (New->getFriendObjectKind() != Decl::FOK_None) {
3740  Diag(New->getLocation(), diag::ext_retained_language_linkage) << New;
3741  Diag(OldLocation, PrevDiag);
3742  } else {
3743  Diag(New->getLocation(), diag::err_different_language_linkage) << New;
3744  Diag(OldLocation, PrevDiag);
3745  return true;
3746  }
3747  }
3748 
3749  // If the function types are compatible, merge the declarations. Ignore the
3750  // exception specifier because it was already checked above in
3751  // CheckEquivalentExceptionSpec, and we don't want follow-on diagnostics
3752  // about incompatible types under -fms-compatibility.
3753  if (Context.hasSameFunctionTypeIgnoringExceptionSpec(OldQTypeForComparison,
3754  NewQType))
3755  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3756 
3757  // If the types are imprecise (due to dependent constructs in friends or
3758  // local extern declarations), it's OK if they differ. We'll check again
3759  // during instantiation.
3760  if (!canFullyTypeCheckRedeclaration(New, Old, NewQType, OldQType))
3761  return false;
3762 
3763  // Fall through for conflicting redeclarations and redefinitions.
3764  }
3765 
3766  // C: Function types need to be compatible, not identical. This handles
3767  // duplicate function decls like "void f(int); void f(enum X);" properly.
3768  if (!getLangOpts().CPlusPlus &&
3769  Context.typesAreCompatible(OldQType, NewQType)) {
3770  const FunctionType *OldFuncType = OldQType->getAs<FunctionType>();
3771  const FunctionType *NewFuncType = NewQType->getAs<FunctionType>();
3772  const FunctionProtoType *OldProto = nullptr;
3773  if (MergeTypeWithOld && isa<FunctionNoProtoType>(NewFuncType) &&
3774  (OldProto = dyn_cast<FunctionProtoType>(OldFuncType))) {
3775  // The old declaration provided a function prototype, but the
3776  // new declaration does not. Merge in the prototype.
3777  assert(!OldProto->hasExceptionSpec() && "Exception spec in C");
3778  SmallVector<QualType, 16> ParamTypes(OldProto->param_types());
3779  NewQType =
3780  Context.getFunctionType(NewFuncType->getReturnType(), ParamTypes,
3781  OldProto->getExtProtoInfo());
3782  New->setType(NewQType);
3783  New->setHasInheritedPrototype();
3784 
3785  // Synthesize parameters with the same types.
3787  for (const auto &ParamType : OldProto->param_types()) {
3788  ParmVarDecl *Param = ParmVarDecl::Create(Context, New, SourceLocation(),
3789  SourceLocation(), nullptr,
3790  ParamType, /*TInfo=*/nullptr,
3791  SC_None, nullptr);
3792  Param->setScopeInfo(0, Params.size());
3793  Param->setImplicit();
3794  Params.push_back(Param);
3795  }
3796 
3797  New->setParams(Params);
3798  }
3799 
3800  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3801  }
3802 
3803  // Check if the function types are compatible when pointer size address
3804  // spaces are ignored.
3805  if (Context.hasSameFunctionTypeIgnoringPtrSizes(OldQType, NewQType))
3806  return false;
3807 
3808  // GNU C permits a K&R definition to follow a prototype declaration
3809  // if the declared types of the parameters in the K&R definition
3810  // match the types in the prototype declaration, even when the
3811  // promoted types of the parameters from the K&R definition differ
3812  // from the types in the prototype. GCC then keeps the types from
3813  // the prototype.
3814  //
3815  // If a variadic prototype is followed by a non-variadic K&R definition,
3816  // the K&R definition becomes variadic. This is sort of an edge case, but
3817  // it's legal per the standard depending on how you read C99 6.7.5.3p15 and
3818  // C99 6.9.1p8.
3819  if (!getLangOpts().CPlusPlus &&
3820  Old->hasPrototype() && !New->hasPrototype() &&
3821  New->getType()->getAs<FunctionProtoType>() &&
3822  Old->getNumParams() == New->getNumParams()) {
3823  SmallVector<QualType, 16> ArgTypes;
3825  const FunctionProtoType *OldProto
3826  = Old->getType()->getAs<FunctionProtoType>();
3827  const FunctionProtoType *NewProto
3828  = New->getType()->getAs<FunctionProtoType>();
3829 
3830  // Determine whether this is the GNU C extension.
3831  QualType MergedReturn = Context.mergeTypes(OldProto->getReturnType(),
3832  NewProto->getReturnType());
3833  bool LooseCompatible = !MergedReturn.isNull();
3834  for (unsigned Idx = 0, End = Old->getNumParams();
3835  LooseCompatible && Idx != End; ++Idx) {
3836  ParmVarDecl *OldParm = Old->getParamDecl(Idx);
3837  ParmVarDecl *NewParm = New->getParamDecl(Idx);
3838  if (Context.typesAreCompatible(OldParm->getType(),
3839  NewProto->getParamType(Idx))) {
3840  ArgTypes.push_back(NewParm->getType());
3841  } else if (Context.typesAreCompatible(OldParm->getType(),
3842  NewParm->getType(),
3843  /*CompareUnqualified=*/true)) {
3844  GNUCompatibleParamWarning Warn = { OldParm, NewParm,
3845  NewProto->getParamType(Idx) };
3846  Warnings.push_back(Warn);
3847  ArgTypes.push_back(NewParm->getType());
3848  } else
3849  LooseCompatible = false;
3850  }
3851 
3852  if (LooseCompatible) {
3853  for (unsigned Warn = 0; Warn < Warnings.size(); ++Warn) {
3854  Diag(Warnings[Warn].NewParm->getLocation(),
3855  diag::ext_param_promoted_not_compatible_with_prototype)
3856  << Warnings[Warn].PromotedType
3857  << Warnings[Warn].OldParm->getType();
3858  if (Warnings[Warn].OldParm->getLocation().isValid())
3859  Diag(Warnings[Warn].OldParm->getLocation(),
3860  diag::note_previous_declaration);
3861  }
3862 
3863  if (MergeTypeWithOld)
3864  New->setType(Context.getFunctionType(MergedReturn, ArgTypes,
3865  OldProto->getExtProtoInfo()));
3866  return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
3867  }
3868 
3869  // Fall through to diagnose conflicting types.
3870  }
3871 
3872  // A function that has already been declared has been redeclared or
3873  // defined with a different type; show an appropriate diagnostic.
3874 
3875  // If the previous declaration was an implicitly-generated builtin
3876  // declaration, then at the very least we should use a specialized note.
3877  unsigned BuiltinID;
3878  if (Old->isImplicit() && (BuiltinID = Old->getBuiltinID())) {
3879  // If it's actually a library-defined builtin function like 'malloc'
3880  // or 'printf', just warn about the incompatible redeclaration.
3881  if (Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) {
3882  Diag(New->getLocation(), diag::warn_redecl_library_builtin) << New;
3883  Diag(OldLocation, diag::note_previous_builtin_declaration)
3884  << Old << Old->getType();
3885  return false;
3886  }
3887 
3888  PrevDiag = diag::note_previous_builtin_declaration;
3889  }
3890 
3891  Diag(New->getLocation(), diag::err_conflicting_types) << New->getDeclName();
3892  Diag(OldLocation, PrevDiag) << Old << Old->getType();
3893  return true;
3894 }
3895 
3896 /// Completes the merge of two function declarations that are
3897 /// known to be compatible.
3898 ///
3899 /// This routine handles the merging of attributes and other
3900 /// properties of function declarations from the old declaration to
3901 /// the new declaration, once we know that New is in fact a
3902 /// redeclaration of Old.
3903 ///
3904 /// \returns false
3906  Scope *S, bool MergeTypeWithOld) {
3907  // Merge the attributes
3908  mergeDeclAttributes(New, Old);
3909 
3910  // Merge "pure" flag.
3911  if (Old->isPure())
3912  New->setPure();
3913 
3914  // Merge "used" flag.
3915  if (Old->getMostRecentDecl()->isUsed(false))
3916  New->setIsUsed();
3917 
3918  // Merge attributes from the parameters. These can mismatch with K&R
3919  // declarations.
3920  if (New->getNumParams() == Old->getNumParams())
3921  for (unsigned i = 0, e = New->getNumParams(); i != e; ++i) {
3922  ParmVarDecl *NewParam = New->getParamDecl(i);
3923  ParmVarDecl *OldParam = Old->getParamDecl(i);
3924  mergeParamDeclAttributes(NewParam, OldParam, *this);
3925  mergeParamDeclTypes(NewParam, OldParam, *this);
3926  }
3927 
3928  if (getLangOpts().CPlusPlus)
3929  return MergeCXXFunctionDecl(New, Old, S);
3930 
3931  // Merge the function types so the we get the composite types for the return
3932  // and argument types. Per C11 6.2.7/4, only update the type if the old decl
3933  // was visible.
3934  QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
3935  if (!Merged.isNull() && MergeTypeWithOld)
3936  New->setType(Merged);
3937 
3938  return false;
3939 }
3940 
3942  ObjCMethodDecl *oldMethod) {
3943  // Merge the attributes, including deprecated/unavailable
3944  AvailabilityMergeKind MergeKind =
3945  isa<ObjCProtocolDecl>(oldMethod->getDeclContext())
3946  ? (oldMethod->isOptional() ? AMK_OptionalProtocolImplementation
3947  : AMK_ProtocolImplementation)
3948  : isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
3949  : AMK_Override;
3950 
3951  mergeDeclAttributes(newMethod, oldMethod, MergeKind);
3952 
3953  // Merge attributes from the parameters.
3955  oe = oldMethod->param_end();
3957  ni = newMethod->param_begin(), ne = newMethod->param_end();
3958  ni != ne && oi != oe; ++ni, ++oi)
3959  mergeParamDeclAttributes(*ni, *oi, *this);
3960 
3961  CheckObjCMethodOverride(newMethod, oldMethod);
3962 }
3963 
3964 static void diagnoseVarDeclTypeMismatch(Sema &S, VarDecl *New, VarDecl* Old) {
3965  assert(!S.Context.hasSameType(New->getType(), Old->getType()));
3966 
3968  ? diag::err_redefinition_different_type
3969  : diag::err_redeclaration_different_type)
3970  << New->getDeclName() << New->getType() << Old->getType();
3971 
3972  diag::kind PrevDiag;
3973  SourceLocation OldLocation;
3974  std::tie(PrevDiag, OldLocation)
3976  S.Diag(OldLocation, PrevDiag);
3977  New->setInvalidDecl();
3978 }
3979 
3980 /// MergeVarDeclTypes - We parsed a variable 'New' which has the same name and
3981 /// scope as a previous declaration 'Old'. Figure out how to merge their types,
3982 /// emitting diagnostics as appropriate.
3983 ///
3984 /// Declarations using the auto type specifier (C++ [decl.spec.auto]) call back
3985 /// to here in AddInitializerToDecl. We can't check them before the initializer
3986 /// is attached.
3988  bool MergeTypeWithOld) {
3989  if (New->isInvalidDecl() || Old->isInvalidDecl())
3990  return;
3991 
3992  QualType MergedT;
3993  if (getLangOpts().CPlusPlus) {
3994  if (New->getType()->isUndeducedType()) {
3995  // We don't know what the new type is until the initializer is attached.
3996  return;
3997  } else if (Context.hasSameType(New->getType(), Old->getType())) {
3998  // These could still be something that needs exception specs checked.
3999  return MergeVarDeclExceptionSpecs(New, Old);
4000  }
4001  // C++ [basic.link]p10:
4002  // [...] the types specified by all declarations referring to a given
4003  // object or function shall be identical, except that declarations for an
4004  // array object can specify array types that differ by the presence or
4005  // absence of a major array bound (8.3.4).
4006  else if (Old->getType()->isArrayType() && New->getType()->isArrayType()) {
4007  const ArrayType *OldArray = Context.getAsArrayType(Old->getType());
4008  const ArrayType *NewArray = Context.getAsArrayType(New->getType());
4009 
4010  // We are merging a variable declaration New into Old. If it has an array
4011  // bound, and that bound differs from Old's bound, we should diagnose the
4012  // mismatch.
4013  if (!NewArray->isIncompleteArrayType() && !NewArray->isDependentType()) {
4014  for (VarDecl *PrevVD = Old->getMostRecentDecl(); PrevVD;
4015  PrevVD = PrevVD->getPreviousDecl()) {
4016  QualType PrevVDTy = PrevVD->getType();
4017  if (PrevVDTy->isIncompleteArrayType() || PrevVDTy->isDependentType())
4018  continue;
4019 
4020  if (!Context.hasSameType(New->getType(), PrevVDTy))
4021  return diagnoseVarDeclTypeMismatch(*this, New, PrevVD);
4022  }
4023  }
4024 
4025  if (OldArray->isIncompleteArrayType() && NewArray->isArrayType()) {
4026  if (Context.hasSameType(OldArray->getElementType(),
4027  NewArray->getElementType()))
4028  MergedT = New->getType();
4029  }
4030  // FIXME: Check visibility. New is hidden but has a complete type. If New
4031  // has no array bound, it should not inherit one from Old, if Old is not
4032  // visible.
4033  else if (OldArray->isArrayType() && NewArray->isIncompleteArrayType()) {
4034  if (Context.hasSameType(OldArray->getElementType(),
4035  NewArray->getElementType()))
4036  MergedT = Old->getType();
4037  }
4038  }
4039  else if (New->getType()->isObjCObjectPointerType() &&
4040  Old->getType()->isObjCObjectPointerType()) {
4041  MergedT = Context.mergeObjCGCQualifiers(New->getType(),
4042  Old->getType());
4043  }
4044  } else {
4045  // C 6.2.7p2:
4046  // All declarations that refer to the same object or function shall have
4047  // compatible type.
4048  MergedT = Context.mergeTypes(New->getType(), Old->getType());
4049  }
4050  if (MergedT.isNull()) {
4051  // It's OK if we couldn't merge types if either type is dependent, for a
4052  // block-scope variable. In other cases (static data members of class
4053  // templates, variable templates, ...), we require the types to be
4054  // equivalent.
4055  // FIXME: The C++ standard doesn't say anything about this.
4056  if ((New->getType()->isDependentType() ||
4057  Old->getType()->isDependentType()) && New->isLocalVarDecl()) {
4058  // If the old type was dependent, we can't merge with it, so the new type
4059  // becomes dependent for now. We'll reproduce the original type when we
4060  // instantiate the TypeSourceInfo for the variable.
4061  if (!New->getType()->isDependentType() && MergeTypeWithOld)
4062  New->setType(Context.DependentTy);
4063  return;
4064  }
4065  return diagnoseVarDeclTypeMismatch(*this, New, Old);
4066  }
4067 
4068  // Don't actually update the type on the new declaration if the old
4069  // declaration was an extern declaration in a different scope.
4070  if (MergeTypeWithOld)
4071  New->setType(MergedT);
4072 }
4073 
4074 static bool mergeTypeWithPrevious(Sema &S, VarDecl *NewVD, VarDecl *OldVD,
4076  // C11 6.2.7p4:
4077  // For an identifier with internal or external linkage declared
4078  // in a scope in which a prior declaration of that identifier is
4079  // visible, if the prior declaration specifies internal or
4080  // external linkage, the type of the identifier at the later
4081  // declaration becomes the composite type.
4082  //
4083  // If the variable isn't visible, we do not merge with its type.
4084  if (Previous.isShadowed())
4085  return false;
4086 
4087  if (S.getLangOpts().CPlusPlus) {
4088  // C++11 [dcl.array]p3:
4089  // If there is a preceding declaration of the entity in the same
4090  // scope in which the bound was specified, an omitted array bound
4091  // is taken to be the same as in that earlier declaration.
4092  return NewVD->isPreviousDeclInSameBlockScope() ||
4093  (!OldVD->getLexicalDeclContext()->isFunctionOrMethod() &&
4095  } else {
4096  // If the old declaration was function-local, don't merge with its
4097  // type unless we're in the same function.
4098  return !OldVD->getLexicalDeclContext()->isFunctionOrMethod() ||
4099  OldVD->getLexicalDeclContext() == NewVD->getLexicalDeclContext();
4100  }
4101 }
4102 
4103 /// MergeVarDecl - We just parsed a variable 'New' which has the same name
4104 /// and scope as a previous declaration 'Old'. Figure out how to resolve this
4105 /// situation, merging decls or emitting diagnostics as appropriate.
4106 ///
4107 /// Tentative definition rules (C99 6.9.2p2) are checked by
4108 /// FinalizeDeclaratorGroup. Unfortunately, we can't analyze tentative
4109 /// definitions here, since the initializer hasn't been attached.
4110 ///
4112  // If the new decl is already invalid, don't do any other checking.
4113  if (New->isInvalidDecl())
4114  return;
4115 
4116  if (!shouldLinkPossiblyHiddenDecl(Previous, New))
4117  return;
4118 
4119  VarTemplateDecl *NewTemplate = New->getDescribedVarTemplate();
4120 
4121  // Verify the old decl was also a variable or variable template.
4122  VarDecl *Old = nullptr;
4123  VarTemplateDecl *OldTemplate = nullptr;
4124  if (Previous.isSingleResult()) {
4125  if (NewTemplate) {
4126  OldTemplate = dyn_cast<VarTemplateDecl>(Previous.getFoundDecl());
4127  Old = OldTemplate ? OldTemplate->getTemplatedDecl() : nullptr;
4128 
4129  if (auto *Shadow =
4130  dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
4131  if (checkUsingShadowRedecl<VarTemplateDecl>(*this, Shadow, NewTemplate))
4132  return New->setInvalidDecl();
4133  } else {
4134  Old = dyn_cast<VarDecl>(Previous.getFoundDecl());
4135 
4136  if (auto *Shadow =
4137  dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
4138  if (checkUsingShadowRedecl<VarDecl>(*this, Shadow, New))
4139  return New->setInvalidDecl();
4140  }
4141  }
4142  if (!Old) {
4143  Diag(New->getLocation(), diag::err_redefinition_different_kind)
4144  << New->getDeclName();
4145  notePreviousDefinition(Previous.getRepresentativeDecl(),
4146  New->getLocation());
4147  return New->setInvalidDecl();
4148  }
4149 
4150  // If the old declaration was found in an inline namespace and the new
4151  // declaration was qualified, update the DeclContext to match.
4153 
4154  // Ensure the template parameters are compatible.
4155  if (NewTemplate &&
4156  !TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
4157  OldTemplate->getTemplateParameters(),
4158  /*Complain=*/true, TPL_TemplateMatch))
4159  return New->setInvalidDecl();
4160 
4161  // C++ [class.mem]p1:
4162  // A member shall not be declared twice in the member-specification [...]
4163  //
4164  // Here, we need only consider static data members.
4165  if (Old->isStaticDataMember() && !New->isOutOfLine()) {
4166  Diag(New->getLocation(), diag::err_duplicate_member)
4167  << New->getIdentifier();
4168  Diag(Old->getLocation(), diag::note_previous_declaration);
4169  New->setInvalidDecl();
4170  }
4171 
4172  mergeDeclAttributes(New, Old);
4173  // Warn if an already-declared variable is made a weak_import in a subsequent
4174  // declaration
4175  if (New->hasAttr<WeakImportAttr>() &&
4176  Old->getStorageClass() == SC_None &&
4177  !Old->hasAttr<WeakImportAttr>()) {
4178  Diag(New->getLocation(), diag::warn_weak_import) << New->getDeclName();
4179  Diag(Old->getLocation(), diag::note_previous_declaration);
4180  // Remove weak_import attribute on new declaration.
4181  New->dropAttr<WeakImportAttr>();
4182  }
4183 
4184  if (const auto *ILA = New->getAttr<InternalLinkageAttr>())
4185  if (!Old->hasAttr<InternalLinkageAttr>()) {
4186  Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
4187  << ILA;
4188  Diag(Old->getLocation(), diag::note_previous_declaration);
4189  New->dropAttr<InternalLinkageAttr>();
4190  }
4191 
4192  // Merge the types.
4193  VarDecl *MostRecent = Old->getMostRecentDecl();
4194  if (MostRecent != Old) {
4195  MergeVarDeclTypes(New, MostRecent,
4196  mergeTypeWithPrevious(*this, New, MostRecent, Previous));
4197  if (New->isInvalidDecl())
4198  return;
4199  }
4200 
4201  MergeVarDeclTypes(New, Old, mergeTypeWithPrevious(*this, New, Old, Previous));
4202  if (New->isInvalidDecl())
4203  return;
4204 
4205  diag::kind PrevDiag;
4206  SourceLocation OldLocation;
4207  std::tie(PrevDiag, OldLocation) =
4209 
4210  // [dcl.stc]p8: Check if we have a non-static decl followed by a static.
4211  if (New->getStorageClass() == SC_Static &&
4212  !New->isStaticDataMember() &&
4213  Old->hasExternalFormalLinkage()) {
4214  if (getLangOpts().MicrosoftExt) {
4215  Diag(New->getLocation(), diag::ext_static_non_static)
4216  << New->getDeclName();
4217  Diag(OldLocation, PrevDiag);
4218  } else {
4219  Diag(New->getLocation(), diag::err_static_non_static)
4220  << New->getDeclName();
4221  Diag(OldLocation, PrevDiag);
4222  return New->setInvalidDecl();
4223  }
4224  }
4225  // C99 6.2.2p4:
4226  // For an identifier declared with the storage-class specifier
4227  // extern in a scope in which a prior declaration of that
4228  // identifier is visible,23) if the prior declaration specifies
4229  // internal or external linkage, the linkage of the identifier at
4230  // the later declaration is the same as the linkage specified at
4231  // the prior declaration. If no prior declaration is visible, or
4232  // if the prior declaration specifies no linkage, then the
4233  // identifier has external linkage.
4234  if (New->hasExternalStorage() && Old->hasLinkage())
4235  /* Okay */;
4236  else if (New->getCanonicalDecl()->getStorageClass() != SC_Static &&
4237  !New->isStaticDataMember() &&
4239  Diag(New->getLocation(), diag::err_non_static_static) << New->getDeclName();
4240  Diag(OldLocation, PrevDiag);
4241  return New->setInvalidDecl();
4242  }
4243 
4244  // Check if extern is followed by non-extern and vice-versa.
4245  if (New->hasExternalStorage() &&
4246  !Old->hasLinkage() && Old->isLocalVarDeclOrParm()) {
4247  Diag(New->getLocation(), diag::err_extern_non_extern) << New->getDeclName();
4248  Diag(OldLocation, PrevDiag);
4249  return New->setInvalidDecl();
4250  }
4251  if (Old->hasLinkage() && New->isLocalVarDeclOrParm() &&
4252  !New->hasExternalStorage()) {
4253  Diag(New->getLocation(), diag::err_non_extern_extern) << New->getDeclName();
4254  Diag(OldLocation, PrevDiag);
4255  return New->setInvalidDecl();
4256  }
4257 
4258  if (CheckRedeclarationModuleOwnership(New, Old))
4259  return;
4260 
4261  // Variables with external linkage are analyzed in FinalizeDeclaratorGroup.
4262 
4263  // FIXME: The test for external storage here seems wrong? We still
4264  // need to check for mismatches.
4265  if (!New->hasExternalStorage() && !New->isFileVarDecl() &&
4266  // Don't complain about out-of-line definitions of static members.
4267  !(Old->getLexicalDeclContext()->isRecord() &&
4268  !New->getLexicalDeclContext()->isRecord())) {
4269  Diag(New->getLocation(), diag::err_redefinition) << New->getDeclName();
4270  Diag(OldLocation, PrevDiag);
4271  return New->setInvalidDecl();
4272  }
4273 
4274  if (New->isInline() && !Old->getMostRecentDecl()->isInline()) {
4275  if (VarDecl *Def = Old->getDefinition()) {
4276  // C++1z [dcl.fcn.spec]p4:
4277  // If the definition of a variable appears in a translation unit before
4278  // its first declaration as inline, the program is ill-formed.
4279  Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
4280  Diag(Def->getLocation(), diag::note_previous_definition);
4281  }
4282  }
4283 
4284  // If this redeclaration makes the variable inline, we may need to add it to
4285  // UndefinedButUsed.
4286  if (!Old->isInline() && New->isInline() && Old->isUsed(false) &&
4287  !Old->getDefinition() && !New->isThisDeclarationADefinition())
4288  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
4289  SourceLocation()));
4290 
4291  if (New->getTLSKind() != Old->getTLSKind()) {
4292  if (!Old->getTLSKind()) {
4293  Diag(New->getLocation(), diag::err_thread_non_thread) << New->getDeclName();
4294  Diag(OldLocation, PrevDiag);
4295  } else if (!New->getTLSKind()) {
4296  Diag(New->getLocation(), diag::err_non_thread_thread) << New->getDeclName();
4297  Diag(OldLocation, PrevDiag);
4298  } else {
4299  // Do not allow redeclaration to change the variable between requiring
4300  // static and dynamic initialization.
4301  // FIXME: GCC allows this, but uses the TLS keyword on the first
4302  // declaration to determine the kind. Do we need to be compatible here?
4303  Diag(New->getLocation(), diag::err_thread_thread_different_kind)
4304  << New->getDeclName() << (New->getTLSKind() == VarDecl::TLS_Dynamic);
4305  Diag(OldLocation, PrevDiag);
4306  }
4307  }
4308 
4309  // C++ doesn't have tentative definitions, so go right ahead and check here.
4310  if (getLangOpts().CPlusPlus &&
4312  if (Old->isStaticDataMember() && Old->getCanonicalDecl()->isInline() &&
4313  Old->getCanonicalDecl()->isConstexpr()) {
4314  // This definition won't be a definition any more once it's been merged.
4315  Diag(New->getLocation(),
4316  diag::warn_deprecated_redundant_constexpr_static_def);
4317  } else if (VarDecl *Def = Old->getDefinition()) {
4318  if (checkVarDeclRedefinition(Def, New))
4319  return;
4320  }
4321  }
4322 
4323  if (haveIncompatibleLanguageLinkages(Old, New)) {
4324  Diag(New->getLocation(), diag::err_different_language_linkage) << New;
4325  Diag(OldLocation, PrevDiag);
4326  New->setInvalidDecl();
4327  return;
4328  }
4329 
4330  // Merge "used" flag.
4331  if (Old->getMostRecentDecl()->isUsed(false))
4332  New->setIsUsed();
4333 
4334  // Keep a chain of previous declarations.
4335  New->setPreviousDecl(Old);
4336  if (NewTemplate)
4337  NewTemplate->setPreviousDecl(OldTemplate);
4338 
4339  // Inherit access appropriately.
4340  New->setAccess(Old->getAccess());
4341  if (NewTemplate)
4342  NewTemplate->setAccess(New->getAccess());
4343 
4344  if (Old->isInline())
4345  New->setImplicitlyInline();
4346 }
4347 
4349  SourceManager &SrcMgr = getSourceManager();
4350  auto FNewDecLoc = SrcMgr.getDecomposedLoc(New);
4351  auto FOldDecLoc = SrcMgr.getDecomposedLoc(Old->getLocation());
4352  auto *FNew = SrcMgr.getFileEntryForID(FNewDecLoc.first);
4353  auto *FOld = SrcMgr.getFileEntryForID(FOldDecLoc.first);
4354  auto &HSI = PP.getHeaderSearchInfo();
4355  StringRef HdrFilename =
4356  SrcMgr.getFilename(SrcMgr.getSpellingLoc(Old->getLocation()));
4357 
4358  auto noteFromModuleOrInclude = [&](Module *Mod,
4359  SourceLocation IncLoc) -> bool {
4360  // Redefinition errors with modules are common with non modular mapped
4361  // headers, example: a non-modular header H in module A that also gets
4362  // included directly in a TU. Pointing twice to the same header/definition
4363  // is confusing, try to get better diagnostics when modules is on.
4364  if (IncLoc.isValid()) {
4365  if (Mod) {
4366  Diag(IncLoc, diag::note_redefinition_modules_same_file)
4367  << HdrFilename.str() << Mod->getFullModuleName();
4368  if (!Mod->DefinitionLoc.isInvalid())
4369  Diag(Mod->DefinitionLoc, diag::note_defined_here)
4370  << Mod->getFullModuleName();
4371  } else {
4372  Diag(IncLoc, diag::note_redefinition_include_same_file)
4373  << HdrFilename.str();
4374  }
4375  return true;
4376  }
4377 
4378  return false;
4379  };
4380 
4381  // Is it the same file and same offset? Provide more information on why
4382  // this leads to a redefinition error.
4383  if (FNew == FOld && FNewDecLoc.second == FOldDecLoc.second) {
4384  SourceLocation OldIncLoc = SrcMgr.getIncludeLoc(FOldDecLoc.first);
4385  SourceLocation NewIncLoc = SrcMgr.getIncludeLoc(FNewDecLoc.first);
4386  bool EmittedDiag =
4387  noteFromModuleOrInclude(Old->getOwningModule(), OldIncLoc);
4388  EmittedDiag |= noteFromModuleOrInclude(getCurrentModule(), NewIncLoc);
4389 
4390  // If the header has no guards, emit a note suggesting one.
4391  if (FOld && !HSI.isFileMultipleIncludeGuarded(FOld))
4392  Diag(Old->getLocation(), diag::note_use_ifdef_guards);
4393 
4394  if (EmittedDiag)
4395  return;
4396  }
4397 
4398  // Redefinition coming from different files or couldn't do better above.
4399  if (Old->getLocation().isValid())
4400  Diag(Old->getLocation(), diag::note_previous_definition);
4401 }
4402 
4403 /// We've just determined that \p Old and \p New both appear to be definitions
4404 /// of the same variable. Either diagnose or fix the problem.
4406  if (!hasVisibleDefinition(Old) &&
4407  (New->getFormalLinkage() == InternalLinkage ||
4408  New->isInline() ||
4409  New->getDescribedVarTemplate() ||
4411  New->getDeclContext()->isDependentContext())) {
4412  // The previous definition is hidden, and multiple definitions are
4413  // permitted (in separate TUs). Demote this to a declaration.
4415 
4416  // Make the canonical definition visible.
4417  if (auto *OldTD = Old->getDescribedVarTemplate())
4418  makeMergedDefinitionVisible(OldTD);
4419  makeMergedDefinitionVisible(Old);
4420  return false;
4421  } else {
4422  Diag(New->getLocation(), diag::err_redefinition) << New;
4423  notePreviousDefinition(Old, New->getLocation());
4424  New->setInvalidDecl();
4425  return true;
4426  }
4427 }
4428 
4429 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
4430 /// no declarator (e.g. "struct foo;") is parsed.
4431 Decl *
4433  RecordDecl *&AnonRecord) {
4434  return ParsedFreeStandingDeclSpec(S, AS, DS, MultiTemplateParamsArg(), false,
4435  AnonRecord);
4436 }
4437 
4438 // The MS ABI changed between VS2013 and VS2015 with regard to numbers used to
4439 // disambiguate entities defined in different scopes.
4440 // While the VS2015 ABI fixes potential miscompiles, it is also breaks
4441 // compatibility.
4442 // We will pick our mangling number depending on which version of MSVC is being
4443 // targeted.
4444 static unsigned getMSManglingNumber(const LangOptions &LO, Scope *S) {
4446  ? S->getMSCurManglingNumber()
4447  : S->getMSLastManglingNumber();
4448 }
4449 
4450 void Sema::handleTagNumbering(const TagDecl *Tag, Scope *TagScope) {
4451  if (!Context.getLangOpts().CPlusPlus)
4452  return;
4453 
4454  if (isa<CXXRecordDecl>(Tag->getParent())) {
4455  // If this tag is the direct child of a class, number it if
4456  // it is anonymous.
4457  if (!Tag->getName().empty() || Tag->getTypedefNameForAnonDecl())
4458  return;
4459  MangleNumberingContext &MCtx =
4460  Context.getManglingNumberContext(Tag->getParent());
4461  Context.setManglingNumber(
4462  Tag, MCtx.getManglingNumber(
4463  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
4464  return;
4465  }
4466 
4467  // If this tag isn't a direct child of a class, number it if it is local.
4468  MangleNumberingContext *MCtx;
4469  Decl *ManglingContextDecl;
4470  std::tie(MCtx, ManglingContextDecl) =
4471  getCurrentMangleNumberContext(Tag->getDeclContext());
4472  if (MCtx) {
4473  Context.setManglingNumber(
4474  Tag, MCtx->getManglingNumber(
4475  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
4476  }
4477 }
4478 
4479 namespace {
4480 struct NonCLikeKind {
4481  enum {
4482  None,
4483  BaseClass,
4484  DefaultMemberInit,
4485  Lambda,
4486  Friend,
4487  OtherMember,
4488  Invalid,
4489  } Kind = None;
4490  SourceRange Range;
4491 
4492  explicit operator bool() { return Kind != None; }
4493 };
4494 }
4495 
4496 /// Determine whether a class is C-like, according to the rules of C++
4497 /// [dcl.typedef] for anonymous classes with typedef names for linkage.
4498 static NonCLikeKind getNonCLikeKindForAnonymousStruct(const CXXRecordDecl *RD) {
4499  if (RD->isInvalidDecl())
4500  return {NonCLikeKind::Invalid, {}};
4501 
4502  // C++ [dcl.typedef]p9: [P1766R1]
4503  // An unnamed class with a typedef name for linkage purposes shall not
4504  //
4505  // -- have any base classes
4506  if (RD->getNumBases())
4507  return {NonCLikeKind::BaseClass,
4509  RD->bases_end()[-1].getEndLoc())};
4510  bool Invalid = false;
4511  for (Decl *D : RD->decls()) {
4512  // Don't complain about things we already diagnosed.
4513  if (D->isInvalidDecl()) {
4514  Invalid = true;
4515  continue;
4516  }
4517 
4518  // -- have any [...] default member initializers
4519  if (auto *FD = dyn_cast<FieldDecl>(D)) {
4520  if (FD->hasInClassInitializer()) {
4521  auto *Init = FD->getInClassInitializer();
4522  return {NonCLikeKind::DefaultMemberInit,
4523  Init ? Init->getSourceRange() : D->getSourceRange()};
4524  }
4525  continue;
4526  }
4527 
4528  // FIXME: We don't allow friend declarations. This violates the wording of
4529  // P1766, but not the intent.
4530  if (isa<FriendDecl>(D))
4531  return {NonCLikeKind::Friend, D->getSourceRange()};
4532 
4533  // -- declare any members other than non-static data members, member
4534  // enumerations, or member classes,
4535  if (isa<StaticAssertDecl>(D) || isa<IndirectFieldDecl>(D) ||
4536  isa<EnumDecl>(D))
4537  continue;
4538  auto *MemberRD = dyn_cast<CXXRecordDecl>(D);
4539  if (!MemberRD) {
4540  if (D->isImplicit())
4541  continue;
4542  return {NonCLikeKind::OtherMember, D->getSourceRange()};
4543  }
4544 
4545  // -- contain a lambda-expression,
4546  if (MemberRD->isLambda())
4547  return {NonCLikeKind::Lambda, MemberRD->getSourceRange()};
4548 
4549  // and all member classes shall also satisfy these requirements
4550  // (recursively).
4551  if (MemberRD->isThisDeclarationADefinition()) {
4552  if (auto Kind = getNonCLikeKindForAnonymousStruct(MemberRD))
4553  return Kind;
4554  }
4555  }
4556 
4557  return {Invalid ? NonCLikeKind::Invalid : NonCLikeKind::None, {}};
4558 }
4559 
4561  TypedefNameDecl *NewTD) {
4562  if (TagFromDeclSpec->isInvalidDecl())
4563  return;
4564 
4565  // Do nothing if the tag already has a name for linkage purposes.
4566  if (TagFromDeclSpec->hasNameForLinkage())
4567  return;
4568 
4569  // A well-formed anonymous tag must always be a TUK_Definition.
4570  assert(TagFromDeclSpec->isThisDeclarationADefinition());
4571 
4572  // The type must match the tag exactly; no qualifiers allowed.
4573  if (!Context.hasSameType(NewTD->getUnderlyingType(),
4574  Context.getTagDeclType(TagFromDeclSpec))) {
4575  if (getLangOpts().CPlusPlus)
4576  Context.addTypedefNameForUnnamedTagDecl(TagFromDeclSpec, NewTD);
4577  return;
4578  }
4579 
4580  // C++ [dcl.typedef]p9: [P1766R1, applied as DR]
4581  // An unnamed class with a typedef name for linkage purposes shall [be
4582  // C-like].
4583  //
4584  // FIXME: Also diagnose if we've already computed the linkage. That ideally
4585  // shouldn't happen, but there are constructs that the language rule doesn't
4586  // disallow for which we can't reasonably avoid computing linkage early.
4587  const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(TagFromDeclSpec);
4588  NonCLikeKind NonCLike = RD ? getNonCLikeKindForAnonymousStruct(RD)
4589  : NonCLikeKind();
4590  bool ChangesLinkage = TagFromDeclSpec->hasLinkageBeenComputed();
4591  if (NonCLike || ChangesLinkage) {
4592  if (NonCLike.Kind == NonCLikeKind::Invalid)
4593  return;
4594 
4595  unsigned DiagID = diag::ext_non_c_like_anon_struct_in_typedef;
4596  if (ChangesLinkage) {
4597  // If the linkage changes, we can't accept this as an extension.
4598  if (NonCLike.Kind == NonCLikeKind::None)
4599  DiagID = diag::err_typedef_changes_linkage;
4600  else
4601  DiagID = diag::err_non_c_like_anon_struct_in_typedef;
4602  }
4603 
4604  SourceLocation FixitLoc =
4605  getLocForEndOfToken(TagFromDeclSpec->getInnerLocStart());
4606  llvm::SmallString<40> TextToInsert;
4607  TextToInsert += ' ';
4608  TextToInsert += NewTD->getIdentifier()->getName();
4609 
4610  Diag(FixitLoc, DiagID)
4611  << isa<TypeAliasDecl>(NewTD)
4612  << FixItHint::CreateInsertion(FixitLoc, TextToInsert);
4613  if (NonCLike.Kind != NonCLikeKind::None) {
4614  Diag(NonCLike.Range.getBegin(), diag::note_non_c_like_anon_struct)
4615  << NonCLike.Kind - 1 << NonCLike.Range;
4616  }
4617  Diag(NewTD->getLocation(), diag::note_typedef_for_linkage_here)
4618  << NewTD << isa<TypeAliasDecl>(NewTD);
4619 
4620  if (ChangesLinkage)
4621  return;
4622  }
4623 
4624  // Otherwise, set this as the anon-decl typedef for the tag.
4625  TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
4626 }
4627 
4629  switch (T) {
4630  case DeclSpec::TST_class:
4631  return 0;
4632  case DeclSpec::TST_struct:
4633  return 1;
4635  return 2;
4636  case DeclSpec::TST_union:
4637  return 3;
4638  case DeclSpec::TST_enum:
4639  return 4;
4640  default:
4641  llvm_unreachable("unexpected type specifier");
4642  }
4643 }
4644 
4645 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
4646 /// no declarator (e.g. "struct foo;") is parsed. It also accepts template
4647 /// parameters to cope with template friend declarations.
4648 Decl *
4650  MultiTemplateParamsArg TemplateParams,
4651  bool IsExplicitInstantiation,
4652  RecordDecl *&AnonRecord) {
4653  Decl *TagD = nullptr;
4654  TagDecl *Tag = nullptr;
4655  if (DS.getTypeSpecType() == DeclSpec::TST_class ||
4660  TagD = DS.getRepAsDecl();
4661 
4662  if (!TagD) // We probably had an error
4663  return nullptr;
4664 
4665  // Note that the above type specs guarantee that the
4666  // type rep is a Decl, whereas in many of the others
4667  // it's a Type.
4668  if (isa<TagDecl>(TagD))
4669  Tag = cast<TagDecl>(TagD);
4670  else if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(TagD))
4671  Tag = CTD->getTemplatedDecl();
4672  }
4673 
4674  if (Tag) {
4675  handleTagNumbering(Tag, S);
4676  Tag->setFreeStanding();
4677  if (Tag->isInvalidDecl())
4678  return Tag;
4679  }
4680 
4681  if (unsigned TypeQuals = DS.getTypeQualifiers()) {
4682  // Enforce C99 6.7.3p2: "Types other than pointer types derived from object
4683  // or incomplete types shall not be restrict-qualified."
4684  if (TypeQuals & DeclSpec::TQ_restrict)
4685  Diag(DS.getRestrictSpecLoc(),
4686  diag::err_typecheck_invalid_restrict_not_pointer_noarg)
4687  << DS.getSourceRange();
4688  }
4689 
4690  if (DS.isInlineSpecified())
4691  Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
4692  << getLangOpts().CPlusPlus17;
4693 
4694  if (DS.hasConstexprSpecifier()) {
4695  // C++0x [dcl.constexpr]p1: constexpr can only be applied to declarations
4696  // and definitions of functions and variables.
4697  // C++2a [dcl.constexpr]p1: The consteval specifier shall be applied only to
4698  // the declaration of a function or function template
4699  if (Tag)
4700  Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
4702  << static_cast<int>(DS.getConstexprSpecifier());
4703  else
4704  Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_wrong_decl_kind)
4705  << static_cast<int>(DS.getConstexprSpecifier());
4706  // Don't emit warnings after this error.
4707  return TagD;
4708  }
4709 
4710  DiagnoseFunctionSpecifiers(DS);
4711 
4712  if (DS.isFriendSpecified()) {
4713  // If we're dealing with a decl but not a TagDecl, assume that
4714  // whatever routines created it handled the friendship aspect.
4715  if (TagD && !Tag)
4716  return nullptr;
4717  return ActOnFriendTypeDecl(S, DS, TemplateParams);
4718  }
4719 
4720  const CXXScopeSpec &SS = DS.getTypeSpecScope();
4721  bool IsExplicitSpecialization =
4722  !TemplateParams.empty() && TemplateParams.back()->size() == 0;
4723  if (Tag && SS.isNotEmpty() && !Tag->isCompleteDefinition() &&
4724  !IsExplicitInstantiation && !IsExplicitSpecialization &&
4725  !isa<ClassTemplatePartialSpecializationDecl>(Tag)) {
4726  // Per C++ [dcl.type.elab]p1, a class declaration cannot have a
4727  // nested-name-specifier unless it is an explicit instantiation
4728  // or an explicit specialization.
4729  //
4730  // FIXME: We allow class template partial specializations here too, per the
4731  // obvious intent of DR1819.
4732  //
4733  // Per C++ [dcl.enum]p1, an opaque-enum-declaration can't either.
4734  Diag(SS.getBeginLoc(), diag::err_standalone_class_nested_name_specifier)
4736  return nullptr;
4737  }
4738 
4739  // Track whether this decl-specifier declares anything.
4740  bool DeclaresAnything = true;
4741 
4742  // Handle anonymous struct definitions.
4743  if (RecordDecl *Record = dyn_cast_or_null<RecordDecl>(Tag)) {
4744  if (!Record->getDeclName() && Record->isCompleteDefinition() &&
4746  if (getLangOpts().CPlusPlus ||
4747  Record->getDeclContext()->isRecord()) {
4748  // If CurContext is a DeclContext that can contain statements,
4749  // RecursiveASTVisitor won't visit the decls that
4750  // BuildAnonymousStructOrUnion() will put into CurContext.
4751  // Also store them here so that they can be part of the
4752  // DeclStmt that gets created in this case.
4753  // FIXME: Also return the IndirectFieldDecls created by
4754  // BuildAnonymousStructOr union, for the same reason?
4755  if (CurContext->isFunctionOrMethod())
4756  AnonRecord = Record;
4757  return BuildAnonymousStructOrUnion(S, DS, AS, Record,
4758  Context.getPrintingPolicy());
4759  }
4760 
4761  DeclaresAnything = false;
4762  }
4763  }
4764 
4765  // C11 6.7.2.1p2:
4766  // A struct-declaration that does not declare an anonymous structure or
4767  // anonymous union shall contain a struct-declarator-list.
4768  //
4769  // This rule also existed in C89 and C99; the grammar for struct-declaration
4770  // did not permit a struct-declaration without a struct-declarator-list.
4771  if (!getLangOpts().CPlusPlus && CurContext->isRecord() &&
4773  // Check for Microsoft C extension: anonymous struct/union member.
4774  // Handle 2 kinds of anonymous struct/union:
4775  // struct STRUCT;
4776  // union UNION;
4777  // and
4778  // STRUCT_TYPE; <- where STRUCT_TYPE is a typedef struct.
4779  // UNION_TYPE; <- where UNION_TYPE is a typedef union.
4780  if ((Tag && Tag->getDeclName()) ||
4782  RecordDecl *Record = nullptr;
4783  if (Tag)
4784  Record = dyn_cast<RecordDecl>(Tag);
4785  else if (const RecordType *RT =
4787  Record = RT->getDecl();
4788  else if (const RecordType *UT = DS.getRepAsType().get()->getAsUnionType())
4789  Record = UT->getDecl();
4790 
4791  if (Record && getLangOpts().MicrosoftExt) {
4792  Diag(DS.getBeginLoc(), diag::ext_ms_anonymous_record)
4793  << Record->isUnion() << DS.getSourceRange();
4794  return BuildMicrosoftCAnonymousStruct(S, DS, Record);
4795  }
4796 
4797  DeclaresAnything = false;
4798  }
4799  }
4800 
4801  // Skip all the checks below if we have a type error.
4802  if (DS.getTypeSpecType() == DeclSpec::TST_error ||
4803  (TagD && TagD->isInvalidDecl()))
4804  return TagD;
4805 
4806  if (getLangOpts().CPlusPlus &&
4808  if (EnumDecl *Enum = dyn_cast_or_null<EnumDecl>(Tag))
4809  if (Enum->enumerator_begin() == Enum->enumerator_end() &&
4810  !Enum->getIdentifier() && !Enum->isInvalidDecl())
4811  DeclaresAnything = false;
4812 
4813  if (!DS.isMissingDeclaratorOk()) {
4814  // Customize diagnostic for a typedef missing a name.
4816  Diag(DS.getBeginLoc(), diag::ext_typedef_without_a_name)
4817  << DS.getSourceRange();
4818  else
4819  DeclaresAnything = false;
4820  }
4821 
4822  if (DS.isModulePrivateSpecified() &&
4823  Tag && Tag->getDeclContext()->isFunctionOrMethod())
4824  Diag(DS.getModulePrivateSpecLoc(), diag::err_module_private_local_class)
4825  << Tag->getTagKind()
4827 
4828  ActOnDocumentableDecl(TagD);
4829 
4830  // C 6.7/2:
4831  // A declaration [...] shall declare at least a declarator [...], a tag,
4832  // or the members of an enumeration.
4833  // C++ [dcl.dcl]p3:
4834  // [If there are no declarators], and except for the declaration of an
4835  // unnamed bit-field, the decl-specifier-seq shall introduce one or more
4836  // names into the program, or shall redeclare a name introduced by a
4837  // previous declaration.
4838  if (!DeclaresAnything) {
4839  // In C, we allow this as a (popular) extension / bug. Don't bother
4840  // producing further diagnostics for redundant qualifiers after this.
4841  Diag(DS.getBeginLoc(), (IsExplicitInstantiation || !TemplateParams.empty())
4842  ? diag::err_no_declarators
4843  : diag::ext_no_declarators)
4844  << DS.getSourceRange();
4845  return TagD;
4846  }
4847 
4848  // C++ [dcl.stc]p1:
4849  // If a storage-class-specifier appears in a decl-specifier-seq, [...] the
4850  // init-declarator-list of the declaration shall not be empty.
4851  // C++ [dcl.fct.spec]p1:
4852  // If a cv-qualifier appears in a decl-specifier-seq, the
4853  // init-declarator-list of the declaration shall not be empty.
4854  //
4855  // Spurious qualifiers here appear to be valid in C.
4856  unsigned DiagID = diag::warn_standalone_specifier;
4857  if (getLangOpts().CPlusPlus)
4858  DiagID = diag::ext_standalone_specifier;
4859 
4860  // Note that a linkage-specification sets a storage class, but
4861  // 'extern "C" struct foo;' is actually valid and not theoretically
4862  // useless.
4863  if (DeclSpec::SCS SCS = DS.getStorageClassSpec()) {
4864  if (SCS == DeclSpec::SCS_mutable)
4865  // Since mutable is not a viable storage class specifier in C, there is
4866  // no reason to treat it as an extension. Instead, diagnose as an error.
4867  Diag(DS.getStorageClassSpecLoc(), diag::err_mutable_nonmember);
4868  else if (!DS.isExternInLinkageSpec() && SCS != DeclSpec::SCS_typedef)
4869  Diag(DS.getStorageClassSpecLoc(), DiagID)
4871  }
4872 
4873  if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
4874  Diag(DS.getThreadStorageClassSpecLoc(), DiagID)
4875  << DeclSpec::getSpecifierName(TSCS);
4876  if (DS.getTypeQualifiers()) {
4878  Diag(DS.getConstSpecLoc(), DiagID) << "const";
4880  Diag(DS.getConstSpecLoc(), DiagID) << "volatile";
4881  // Restrict is covered above.
4883  Diag(DS.getAtomicSpecLoc(), DiagID) << "_Atomic";
4885  Diag(DS.getUnalignedSpecLoc(), DiagID) << "__unaligned";
4886  }
4887 
4888  // Warn about ignored type attributes, for example:
4889  // __attribute__((aligned)) struct A;
4890  // Attributes should be placed after tag to apply to type declaration.
4891  if (!DS.getAttributes().empty()) {
4892  DeclSpec::TST TypeSpecType = DS.getTypeSpecType();
4893  if (TypeSpecType == DeclSpec::TST_class ||
4894  TypeSpecType == DeclSpec::TST_struct ||
4895  TypeSpecType == DeclSpec::TST_interface ||
4896  TypeSpecType == DeclSpec::TST_union ||
4897  TypeSpecType == DeclSpec::TST_enum) {
4898  for (const ParsedAttr &AL : DS.getAttributes())
4899  Diag(AL.getLoc(), diag::warn_declspec_attribute_ignored)
4900  << AL << GetDiagnosticTypeSpecifierID(TypeSpecType);
4901  }
4902  }
4903 
4904  return TagD;
4905 }
4906 
4907 /// We are trying to inject an anonymous member into the given scope;
4908 /// check if there's an existing declaration that can't be overloaded.
4909 ///
4910 /// \return true if this is a forbidden redeclaration
4911 static bool CheckAnonMemberRedeclaration(Sema &SemaRef,
4912  Scope *S,
4913  DeclContext *Owner,
4914  DeclarationName Name,
4915  SourceLocation NameLoc,
4916  bool IsUnion) {
4917  LookupResult R(SemaRef, Name, NameLoc, Sema::LookupMemberName,
4919  if (!SemaRef.LookupName(R, S)) return false;
4920 
4921  // Pick a representative declaration.
4923  assert(PrevDecl && "Expected a non-null Decl");
4924 
4925  if (!SemaRef.isDeclInScope(PrevDecl, Owner, S))
4926  return false;
4927 
4928  SemaRef.Diag(NameLoc, diag::err_anonymous_record_member_redecl)
4929  << IsUnion << Name;
4930  SemaRef.Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
4931 
4932  return true;
4933 }
4934 
4935 /// InjectAnonymousStructOrUnionMembers - Inject the members of the
4936 /// anonymous struct or union AnonRecord into the owning context Owner
4937 /// and scope S. This routine will be invoked just after we realize
4938 /// that an unnamed union or struct is actually an anonymous union or
4939 /// struct, e.g.,
4940 ///
4941 /// @code
4942 /// union {
4943 /// int i;
4944 /// float f;
4945 /// }; // InjectAnonymousStructOrUnionMembers called here to inject i and
4946 /// // f into the surrounding scope.x
4947 /// @endcode
4948 ///
4949 /// This routine is recursive, injecting the names of nested anonymous
4950 /// structs/unions into the owning context and scope as well.
4951 static bool
4953  RecordDecl *AnonRecord, AccessSpecifier AS,
4954  SmallVectorImpl<NamedDecl *> &Chaining) {
4955  bool Invalid = false;
4956 
4957  // Look every FieldDecl and IndirectFieldDecl with a name.
4958  for (auto *D : AnonRecord->decls()) {
4959  if ((isa<FieldDecl>(D) || isa<IndirectFieldDecl>(D)) &&
4960  cast<NamedDecl>(D)->getDeclName()) {
4961  ValueDecl *VD = cast<ValueDecl>(D);
4962  if (CheckAnonMemberRedeclaration(SemaRef, S, Owner, VD->getDeclName(),
4963  VD->getLocation(),
4964  AnonRecord->isUnion())) {
4965  // C++ [class.union]p2:
4966  // The names of the members of an anonymous union shall be
4967  // distinct from the names of any other entity in the
4968  // scope in which the anonymous union is declared.
4969  Invalid = true;
4970  } else {
4971  // C++ [class.union]p2:
4972  // For the purpose of name lookup, after the anonymous union
4973  // definition, the members of the anonymous union are
4974  // considered to have been defined in the scope in which the
4975  // anonymous union is declared.
4976  unsigned OldChainingSize = Chaining.size();
4977  if (IndirectFieldDecl *IF = dyn_cast<IndirectFieldDecl>(VD))
4978  Chaining.append(IF->chain_begin(), IF->chain_end());
4979  else
4980  Chaining.push_back(VD);
4981 
4982  assert(Chaining.size() >= 2);
4983  NamedDecl **NamedChain =
4984  new (SemaRef.Context)NamedDecl*[Chaining.size()];
4985  for (unsigned i = 0; i < Chaining.size(); i++)
4986  NamedChain[i] = Chaining[i];
4987 
4989  SemaRef.Context, Owner, VD->getLocation(), VD->getIdentifier(),
4990  VD->getType(), {NamedChain, Chaining.size()});
4991 
4992  for (const auto *Attr : VD->attrs())
4993  IndirectField->addAttr(Attr->clone(SemaRef.Context));
4994 
4995  IndirectField->setAccess(AS);
4996  IndirectField->setImplicit();
4997  SemaRef.PushOnScopeChains(IndirectField, S);
4998 
4999  // That includes picking up the appropriate access specifier.
5000  if (AS != AS_none) IndirectField->setAccess(AS);
5001 
5002  Chaining.resize(OldChainingSize);
5003  }
5004  }
5005  }
5006 
5007  return Invalid;
5008 }
5009 
5010 /// StorageClassSpecToVarDeclStorageClass - Maps a DeclSpec::SCS to
5011 /// a VarDecl::StorageClass. Any error reporting is up to the caller:
5012 /// illegal input values are mapped to SC_None.
5013 static StorageClass
5015  DeclSpec::SCS StorageClassSpec = DS.getStorageClassSpec();
5016  assert(StorageClassSpec != DeclSpec::SCS_typedef &&
5017  "Parser allowed 'typedef' as storage class VarDecl.");
5018  switch (StorageClassSpec) {
5019  case DeclSpec::SCS_unspecified: return SC_None;
5020  case DeclSpec::SCS_extern:
5021  if (DS.isExternInLinkageSpec())
5022  return SC_None;
5023  return SC_Extern;
5024  case DeclSpec::SCS_static: return SC_Static;
5025  case DeclSpec::SCS_auto: return SC_Auto;
5026  case DeclSpec::SCS_register: return SC_Register;
5028  // Illegal SCSs map to None: error reporting is up to the caller.
5029  case DeclSpec::SCS_mutable: // Fall through.
5030  case DeclSpec::SCS_typedef: return SC_None;
5031  }
5032  llvm_unreachable("unknown storage class specifier");
5033 }
5034 
5036  assert(Record->hasInClassInitializer());
5037 
5038  for (const auto *I : Record->decls()) {
5039  const auto *FD = dyn_cast<FieldDecl>(I);
5040  if (const auto *IFD = dyn_cast<IndirectFieldDecl>(I))
5041  FD = IFD->getAnonField();
5042  if (FD && FD->hasInClassInitializer())
5043  return FD->getLocation();
5044  }
5045 
5046  llvm_unreachable("couldn't find in-class initializer");
5047 }
5048 
5050  SourceLocation DefaultInitLoc) {
5051  if (!Parent->isUnion() || !Parent->hasInClassInitializer())
5052  return;
5053 
5054  S.Diag(DefaultInitLoc, diag::err_multiple_mem_union_initialization);
5055  S.Diag(findDefaultInitializer(Parent), diag::note_previous_initializer) << 0;
5056 }
5057 
5059  CXXRecordDecl *AnonUnion) {
5060  if (!Parent->isUnion() || !Parent->hasInClassInitializer())
5061  return;
5062 
5064 }
5065 
5066 /// BuildAnonymousStructOrUnion - Handle the declaration of an
5067 /// anonymous structure or union. Anonymous unions are a C++ feature
5068 /// (C++ [class.union]) and a C11 feature; anonymous structures
5069 /// are a C11 feature and GNU C++ extension.
5071  AccessSpecifier AS,
5072  RecordDecl *Record,
5073  const PrintingPolicy &Policy) {
5074  DeclContext *Owner = Record->getDeclContext();
5075 
5076  // Diagnose whether this anonymous struct/union is an extension.
5077  if (Record->isUnion() && !getLangOpts().CPlusPlus && !getLangOpts().C11)
5078  Diag(Record->getLocation(), diag::ext_anonymous_union);
5079  else if (!Record->isUnion() && getLangOpts().CPlusPlus)
5080  Diag(Record->getLocation(), diag::ext_gnu_anonymous_struct);
5081  else if (!Record->isUnion() && !getLangOpts().C11)
5082  Diag(Record->getLocation(), diag::ext_c11_anonymous_struct);
5083 
5084  // C and C++ require different kinds of checks for anonymous
5085  // structs/unions.
5086  bool Invalid = false;
5087  if (getLangOpts().CPlusPlus) {
5088  const char *PrevSpec = nullptr;
5089  if (Record->isUnion()) {
5090  // C++ [class.union]p6:
5091  // C++17 [class.union.anon]p2:
5092  // Anonymous unions declared in a named namespace or in the
5093  // global namespace shall be declared static.
5094  unsigned DiagID;
5095  DeclContext *OwnerScope = Owner->getRedeclContext();
5097  (OwnerScope->isTranslationUnit() ||
5098  (OwnerScope->isNamespace() &&
5099  !cast<NamespaceDecl>(OwnerScope)->isAnonymousNamespace()))) {
5100  Diag(Record->getLocation(), diag::err_anonymous_union_not_static)
5101  << FixItHint::CreateInsertion(Record->getLocation(), "static ");
5102 
5103  // Recover by adding 'static'.
5105  PrevSpec, DiagID, Policy);
5106  }
5107  // C++ [class.union]p6:
5108  // A storage class is not allowed in a declaration of an
5109  // anonymous union in a class scope.
5111  isa<RecordDecl>(Owner)) {
5113  diag::err_anonymous_union_with_storage_spec)
5115 
5116  // Recover by removing the storage specifier.
5118  SourceLocation(),
5119  PrevSpec, DiagID, Context.getPrintingPolicy());
5120  }
5121  }
5122 
5123  // Ignore const/volatile/restrict qualifiers.
5124  if (DS.getTypeQualifiers()) {
5126  Diag(DS.getConstSpecLoc(), diag::ext_anonymous_struct_union_qualified)
5127  << Record->isUnion() << "const"
5130  Diag(DS.getVolatileSpecLoc(),
5131  diag::ext_anonymous_struct_union_qualified)
5132  << Record->isUnion() << "volatile"
5135  Diag(DS.getRestrictSpecLoc(),
5136  diag::ext_anonymous_struct_union_qualified)
5137  << Record->isUnion() << "restrict"
5140  Diag(DS.getAtomicSpecLoc(),
5141  diag::ext_anonymous_struct_union_qualified)
5142  << Record->isUnion() << "_Atomic"
5146  diag::ext_anonymous_struct_union_qualified)
5147  << Record->isUnion() << "__unaligned"
5149 
5150  DS.ClearTypeQualifiers();
5151  }
5152 
5153  // C++ [class.union]p2:
5154  // The member-specification of an anonymous union shall only
5155  // define non-static data members. [Note: nested types and
5156  // functions cannot be declared within an anonymous union. ]
5157  for (auto *Mem : Record->decls()) {
5158  // Ignore invalid declarations; we already diagnosed them.
5159  if (Mem->isInvalidDecl())
5160  continue;
5161 
5162  if (auto *FD = dyn_cast<FieldDecl>(Mem)) {
5163  // C++ [class.union]p3:
5164  // An anonymous union shall not have private or protected
5165  // members (clause 11).
5166  assert(FD->getAccess() != AS_none);
5167  if (FD->getAccess() != AS_public) {
5168  Diag(FD->getLocation(), diag::err_anonymous_record_nonpublic_member)
5169  << Record->isUnion() << (FD->getAccess() == AS_protected);
5170  Invalid = true;
5171  }
5172 
5173  // C++ [class.union]p1
5174  // An object of a class with a non-trivial constructor, a non-trivial
5175  // copy constructor, a non-trivial destructor, or a non-trivial copy
5176  // assignment operator cannot be a member of a union, nor can an
5177  // array of such objects.
5178  if (CheckNontrivialField(FD))
5179  Invalid = true;
5180  } else if (Mem->isImplicit()) {
5181  // Any implicit members are fine.
5182  } else if (isa<TagDecl>(Mem) && Mem->getDeclContext() != Record) {
5183  // This is a type that showed up in an
5184  // elaborated-type-specifier inside the anonymous struct or
5185  // union, but which actually declares a type outside of the
5186  // anonymous struct or union. It's okay.
5187  } else if (auto *MemRecord = dyn_cast<RecordDecl>(Mem)) {
5188  if (!MemRecord->isAnonymousStructOrUnion() &&
5189  MemRecord->getDeclName()) {
5190  // Visual C++ allows type definition in anonymous struct or union.
5191  if (getLangOpts().MicrosoftExt)
5192  Diag(MemRecord->getLocation(), diag::ext_anonymous_record_with_type)
5193  << Record->isUnion();
5194  else {
5195  // This is a nested type declaration.
5196  Diag(MemRecord->getLocation(), diag::err_anonymous_record_with_type)
5197  << Record->isUnion();
5198  Invalid = true;
5199  }
5200  } else {
5201  // This is an anonymous type definition within another anonymous type.
5202  // This is a popular extension, provided by Plan9, MSVC and GCC, but
5203  // not part of standard C++.
5204  Diag(MemRecord->getLocation(),
5205  diag::ext_anonymous_record_with_anonymous_type)
5206  << Record->isUnion();
5207  }
5208  } else if (isa<AccessSpecDecl>(Mem)) {
5209  // Any access specifier is fine.
5210  } else if (isa<StaticAssertDecl>(Mem)) {
5211  // In C++1z, static_assert declarations are also fine.
5212  } else {
5213  // We have something that isn't a non-static data
5214  // member. Complain about it.
5215  unsigned DK = diag::err_anonymous_record_bad_member;
5216  if (isa<TypeDecl>(Mem))
5217  DK = diag::err_anonymous_record_with_type;
5218  else if (isa<FunctionDecl>(Mem))
5219  DK = diag::err_anonymous_record_with_function;
5220  else if (isa<VarDecl>(Mem))
5221  DK = diag::err_anonymous_record_with_static;
5222 
5223  // Visual C++ allows type definition in anonymous struct or union.
5224  if (getLangOpts().MicrosoftExt &&
5225  DK == diag::err_anonymous_record_with_type)
5226  Diag(Mem->getLocation(), diag::ext_anonymous_record_with_type)
5227  << Record->isUnion();
5228  else {
5229  Diag(Mem->getLocation(), DK) << Record->isUnion();
5230  Invalid = true;
5231  }
5232  }
5233  }
5234 
5235  // C++11 [class.union]p8 (DR1460):
5236  // At most one variant member of a union may have a
5237  // brace-or-equal-initializer.
5238  if (cast<CXXRecordDecl>(Record)->hasInClassInitializer() &&
5239  Owner->isRecord())
5240  checkDuplicateDefaultInit(*this, cast<CXXRecordDecl>(Owner),
5241  cast<CXXRecordDecl>(Record));
5242  }
5243 
5244  if (!Record->isUnion() && !Owner->isRecord()) {
5245  Diag(Record->getLocation(), diag::err_anonymous_struct_not_member)
5246  << getLangOpts().CPlusPlus;
5247  Invalid = true;
5248  }
5249 
5250  // C++ [dcl.dcl]p3:
5251  // [If there are no declarators], and except for the declaration of an
5252  // unnamed bit-field, the decl-specifier-seq shall introduce one or more
5253  // names into the program
5254  // C++ [class.mem]p2:
5255  // each such member-declaration shall either declare at least one member
5256  // name of the class or declare at least one unnamed bit-field
5257  //
5258  // For C this is an error even for a named struct, and is diagnosed elsewhere.
5259  if (getLangOpts().CPlusPlus && Record->field_empty())
5260  Diag(DS.getBeginLoc(), diag::ext_no_declarators) << DS.getSourceRange();
5261 
5262  // Mock up a declarator.
5264  TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
5265  assert(TInfo && "couldn't build declarator info for anonymous struct/union");
5266 
5267  // Create a declaration for this anonymous struct/union.
5268  NamedDecl *Anon = nullptr;
5269  if (RecordDecl *OwningClass = dyn_cast<RecordDecl>(Owner)) {
5270  Anon = FieldDecl::Create(
5271  Context, OwningClass, DS.getBeginLoc(), Record->getLocation(),
5272  /*IdentifierInfo=*/nullptr, Context.getTypeDeclType(Record), TInfo,
5273  /*BitWidth=*/nullptr, /*Mutable=*/false,
5274  /*InitStyle=*/ICIS_NoInit);
5275  Anon->setAccess(AS);
5276  ProcessDeclAttributes(S, Anon, Dc);
5277 
5278  if (getLangOpts().CPlusPlus)
5279  FieldCollector->Add(cast<FieldDecl>(Anon));
5280  } else {
5281  DeclSpec::SCS SCSpec = DS.getStorageClassSpec();
5283  if (SCSpec == DeclSpec::SCS_mutable) {
5284  // mutable can only appear on non-static class members, so it's always
5285  // an error here
5286  Diag(Record->getLocation(), diag::err_mutable_nonmember);
5287  Invalid = true;
5288  SC = SC_None;
5289  }
5290 
5291  assert(DS.getAttributes().empty() && "No attribute expected");
5292  Anon = VarDecl::Create(Context, Owner, DS.getBeginLoc(),
5293  Record->getLocation(), /*IdentifierInfo=*/nullptr,
5294  Context.getTypeDeclType(Record), TInfo, SC);
5295 
5296  // Default-initialize the implicit variable. This initialization will be
5297  // trivial in almost all cases, except if a union member has an in-class
5298  // initializer:
5299  // union { int n = 0; };
5300  if (!Invalid)
5301  ActOnUninitializedDecl(Anon);
5302  }
5303  Anon->setImplicit();
5304 
5305  // Mark this as an anonymous struct/union type.
5306  Record->setAnonymousStructOrUnion(true);
5307 
5308  // Add the anonymous struct/union object to the current
5309  // context. We'll be referencing this object when we refer to one of
5310  // its members.
5311  Owner->addDecl(Anon);
5312 
5313  // Inject the members of the anonymous struct/union into the owning
5314  // context and into the identifier resolver chain for name lookup
5315  // purposes.
5317  Chain.push_back(Anon);
5318 
5319  if (InjectAnonymousStructOrUnionMembers(*this, S, Owner, Record, AS, Chain))
5320  Invalid = true;
5321 
5322  if (VarDecl *NewVD = dyn_cast<VarDecl>(Anon)) {
5323  if (getLangOpts().CPlusPlus && NewVD->isStaticLocal()) {
5324  MangleNumberingContext *MCtx;
5325  Decl *ManglingContextDecl;
5326  std::tie(MCtx, ManglingContextDecl) =
5327  getCurrentMangleNumberContext(NewVD->getDeclContext());
5328  if (MCtx) {
5329  Context.setManglingNumber(
5330  NewVD, MCtx->getManglingNumber(
5331  NewVD, getMSManglingNumber(getLangOpts(), S)));
5332  Context.setStaticLocalNumber(NewVD, MCtx->getStaticLocalNumber(NewVD));
5333  }
5334  }
5335  }
5336 
5337  if (Invalid)
5338  Anon->setInvalidDecl();
5339 
5340  return Anon;
5341 }
5342 
5343 /// BuildMicrosoftCAnonymousStruct - Handle the declaration of an
5344 /// Microsoft C anonymous structure.
5345 /// Ref: http://msdn.microsoft.com/en-us/library/z2cx9y4f.aspx
5346 /// Example:
5347 ///
5348 /// struct A { int a; };
5349 /// struct B { struct A; int b; };
5350 ///
5351 /// void foo() {
5352 /// B var;
5353 /// var.a = 3;
5354 /// }
5355 ///
5357  RecordDecl *Record) {
5358  assert(Record && "expected a record!");
5359 
5360  // Mock up a declarator.
5362  TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
5363  assert(TInfo && "couldn't build declarator info for anonymous struct");
5364 
5365  auto *ParentDecl = cast<RecordDecl>(CurContext);
5366  QualType RecTy = Context.getTypeDeclType(Record);
5367 
5368  // Create a declaration for this anonymous struct.
5369  NamedDecl *Anon =
5370  FieldDecl::Create(Context, ParentDecl, DS.getBeginLoc(), DS.getBeginLoc(),
5371  /*IdentifierInfo=*/nullptr, RecTy, TInfo,
5372  /*BitWidth=*/nullptr, /*Mutable=*/false,
5373  /*InitStyle=*/ICIS_NoInit);
5374  Anon->setImplicit();
5375 
5376  // Add the anonymous struct object to the current context.
5377  CurContext->addDecl(Anon);
5378 
5379  // Inject the members of the anonymous struct into the current
5380  // context and into the identifier resolver chain for name lookup
5381  // purposes.
5383  Chain.push_back(Anon);
5384 
5385  RecordDecl *RecordDef = Record->getDefinition();
5386  if (RequireCompleteSizedType(Anon->getLocation(), RecTy,
5387  diag::err_field_incomplete_or_sizeless) ||
5388  InjectAnonymousStructOrUnionMembers(*this, S, CurContext, RecordDef,
5389  AS_none, Chain)) {
5390  Anon->setInvalidDecl();
5391  ParentDecl->setInvalidDecl();
5392  }
5393 
5394  return Anon;
5395 }
5396 
5397 /// GetNameForDeclarator - Determine the full declaration name for the
5398 /// given Declarator.
5400  return GetNameFromUnqualifiedId(D.getName());
5401 }
5402 
5403 /// Retrieves the declaration name from a parsed unqualified-id.
5406  DeclarationNameInfo NameInfo;
5407  NameInfo.setLoc(Name.StartLocation);
5408 
5409  switch (Name.getKind()) {
5410 
5413  NameInfo.setName(Name.Identifier);
5414  return NameInfo;
5415 
5417  // C++ [temp.deduct.guide]p3:
5418  // The simple-template-id shall name a class template specialization.
5419  // The template-name shall be the same identifier as the template-name
5420  // of the simple-template-id.
5421  // These together intend to imply that the template-name shall name a
5422  // class template.
5423  // FIXME: template<typename T> struct X {};
5424  // template<typename T> using Y = X<T>;
5425  // Y(int) -> Y<int>;
5426  // satisfies these rules but does not name a class template.
5427  TemplateName TN = Name.TemplateName.get().get();
5428  auto *Template = TN.getAsTemplateDecl();
5429  if (!Template || !isa<ClassTemplateDecl>(Template)) {
5430  Diag(Name.StartLocation,
5431  diag::err_deduction_guide_name_not_class_template)
5432  << (int)getTemplateNameKindForDiagnostics(TN) << TN;
5433  if (Template)
5434  Diag(Template->getLocation(), diag::note_template_decl_here);
5435  return DeclarationNameInfo();
5436  }
5437 
5438  NameInfo.setName(
5439  Context.DeclarationNames.getCXXDeductionGuideName(Template));
5440  return NameInfo;
5441  }
5442 
5444  NameInfo.setName(Context.DeclarationNames.getCXXOperatorName(
5445  Name.OperatorFunctionId.Operator));
5447  Name.OperatorFunctionId.SymbolLocations[0], Name.EndLocation));
5448  return NameInfo;
5449 
5452  Name.Identifier));
5453  NameInfo.setCXXLiteralOperatorNameLoc(Name.EndLocation);
5454  return NameInfo;
5455 
5457  TypeSourceInfo *TInfo;
5458  QualType Ty = GetTypeFromParser(Name.ConversionFunctionId, &TInfo);
5459  if (Ty.isNull())
5460  return DeclarationNameInfo();
5462  Context.getCanonicalType(Ty)));
5463  NameInfo.setNamedTypeInfo(TInfo);
5464  return NameInfo;
5465  }
5466 
5468  TypeSourceInfo *TInfo;
5469  QualType Ty = GetTypeFromParser(Name.ConstructorName, &TInfo);
5470  if (Ty.isNull())
5471  return DeclarationNameInfo();
5473  Context.getCanonicalType(Ty)));
5474  NameInfo.setNamedTypeInfo(TInfo);
5475  return NameInfo;
5476  }
5477 
5479  // In well-formed code, we can only have a constructor
5480  // template-id that refers to the current context, so go there
5481  // to find the actual type being constructed.
5482  CXXRecordDecl *CurClass = dyn_cast<CXXRecordDecl>(CurContext);
5483  if (!CurClass || CurClass->getIdentifier() != Name.TemplateId->Name)
5484  return DeclarationNameInfo();
5485 
5486  // Determine the type of the class being constructed.
5487  QualType CurClassType = Context.getTypeDeclType(CurClass);
5488 
5489  // FIXME: Check two things: that the template-id names the same type as
5490  // CurClassType, and that the template-id does not occur when the name
5491  // was qualified.
5492 
5494  Context.getCanonicalType(CurClassType)));
5495  // FIXME: should we retrieve TypeSourceInfo?
5496  NameInfo.setNamedTypeInfo(nullptr);
5497  return NameInfo;
5498  }
5499 
5501  TypeSourceInfo *TInfo;
5502  QualType Ty = GetTypeFromParser(Name.DestructorName, &TInfo);
5503  if (Ty.isNull())
5504  return DeclarationNameInfo();
5506  Context.getCanonicalType(Ty)));
5507  NameInfo.setNamedTypeInfo(TInfo);
5508  return NameInfo;
5509  }
5510 
5512  TemplateName TName = Name.TemplateId->Template.get();
5513  SourceLocation TNameLoc = Name.TemplateId->TemplateNameLoc;
5514  return Context.ge