1//===--- SemaDeclObjC.cpp - Semantic Analysis for ObjC 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 Objective C declarations.
10//
11//===----------------------------------------------------------------------===//
12
13#include "TypeLocBuilder.h"
14#include "clang/AST/ASTConsumer.h"
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/ASTMutationListener.h"
17#include "clang/AST/DeclObjC.h"
18#include "clang/AST/Expr.h"
19#include "clang/AST/ExprObjC.h"
20#include "clang/AST/RecursiveASTVisitor.h"
21#include "clang/Basic/SourceManager.h"
22#include "clang/Sema/DeclSpec.h"
23#include "clang/Sema/Lookup.h"
24#include "clang/Sema/Scope.h"
25#include "clang/Sema/ScopeInfo.h"
26#include "clang/Sema/SemaInternal.h"
27#include "llvm/ADT/DenseMap.h"
28#include "llvm/ADT/DenseSet.h"
29
30using namespace clang;
31
32/// Check whether the given method, which must be in the 'init'
33/// family, is a valid member of that family.
34///
35/// \param receiverTypeIfCall - if null, check this as if declaring it;
36///   if non-null, check this as if making a call to it with the given
37///   receiver type
38///
39/// \return true to indicate that there was an error and appropriate
40///   actions were taken
41bool Sema::checkInitMethod(ObjCMethodDecl *method,
42                           QualType receiverTypeIfCall) {
43  if (method->isInvalidDecl()) return true;
44
45  // This castAs is safe: methods that don't return an object
46  // pointer won't be inferred as inits and will reject an explicit
47  // objc_method_family(init).
48
49  // We ignore protocols here.  Should we?  What about Class?
50
51  const ObjCObjectType *result =
52      method->getReturnType()->castAs<ObjCObjectPointerType>()->getObjectType();
53
54  if (result->isObjCId()) {
55    return false;
56  } else if (result->isObjCClass()) {
57    // fall through: always an error
58  } else {
59    ObjCInterfaceDecl *resultClass = result->getInterface();
60    assert(resultClass && "unexpected object type!");
61
62    // It's okay for the result type to still be a forward declaration
63    // if we're checking an interface declaration.
64    if (!resultClass->hasDefinition()) {
65      if (receiverTypeIfCall.isNull() &&
66          !isa<ObjCImplementationDecl>(method->getDeclContext()))
67        return false;
68
69    // Otherwise, we try to compare class types.
70    } else {
71      // If this method was declared in a protocol, we can't check
72      // anything unless we have a receiver type that's an interface.
73      const ObjCInterfaceDecl *receiverClass = nullptr;
74      if (isa<ObjCProtocolDecl>(method->getDeclContext())) {
75        if (receiverTypeIfCall.isNull())
76          return false;
77
78        receiverClass = receiverTypeIfCall->castAs<ObjCObjectPointerType>()
79          ->getInterfaceDecl();
80
81        // This can be null for calls to e.g. id<Foo>.
82        if (!receiverClass) return false;
83      } else {
84        receiverClass = method->getClassInterface();
85        assert(receiverClass && "method not associated with a class!");
86      }
87
88      // If either class is a subclass of the other, it's fine.
89      if (receiverClass->isSuperClassOf(resultClass) ||
90          resultClass->isSuperClassOf(receiverClass))
91        return false;
92    }
93  }
94
95  SourceLocation loc = method->getLocation();
96
97  // If we're in a system header, and this is not a call, just make
98  // the method unusable.
99  if (receiverTypeIfCall.isNull() && getSourceManager().isInSystemHeader(loc)) {
100    method->addAttr(UnavailableAttr::CreateImplicit(Context, "",
101                      UnavailableAttr::IR_ARCInitReturnsUnrelated, loc));
102    return true;
103  }
104
105  // Otherwise, it's an error.
106  Diag(loc, diag::err_arc_init_method_unrelated_result_type);
107  method->setInvalidDecl();
108  return true;
109}
110
111/// Issue a warning if the parameter of the overridden method is non-escaping
112/// but the parameter of the overriding method is not.
113static bool diagnoseNoescape(const ParmVarDecl *NewD, const ParmVarDecl *OldD,
114                             Sema &S) {
115  if (OldD->hasAttr<NoEscapeAttr>() && !NewD->hasAttr<NoEscapeAttr>()) {
116    S.Diag(NewD->getLocation(), diag::warn_overriding_method_missing_noescape);
117    S.Diag(OldD->getLocation(), diag::note_overridden_marked_noescape);
118    return false;
119  }
120
121  return true;
122}
123
124/// Produce additional diagnostics if a category conforms to a protocol that
125/// defines a method taking a non-escaping parameter.
126static void diagnoseNoescape(const ParmVarDecl *NewD, const ParmVarDecl *OldD,
127                             const ObjCCategoryDecl *CD,
128                             const ObjCProtocolDecl *PD, Sema &S) {
129  if (!diagnoseNoescape(NewD, OldD, S))
130    S.Diag(CD->getLocation(), diag::note_cat_conform_to_noescape_prot)
131        << CD->IsClassExtension() << PD
132        << cast<ObjCMethodDecl>(NewD->getDeclContext());
133}
134
135void Sema::CheckObjCMethodOverride(ObjCMethodDecl *NewMethod,
136                                   const ObjCMethodDecl *Overridden) {
137  if (Overridden->hasRelatedResultType() &&
138      !NewMethod->hasRelatedResultType()) {
139    // This can only happen when the method follows a naming convention that
140    // implies a related result type, and the original (overridden) method has
141    // a suitable return type, but the new (overriding) method does not have
142    // a suitable return type.
143    QualType ResultType = NewMethod->getReturnType();
144    SourceRange ResultTypeRange = NewMethod->getReturnTypeSourceRange();
145
146    // Figure out which class this method is part of, if any.
147    ObjCInterfaceDecl *CurrentClass
148      = dyn_cast<ObjCInterfaceDecl>(NewMethod->getDeclContext());
149    if (!CurrentClass) {
150      DeclContext *DC = NewMethod->getDeclContext();
151      if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(DC))
152        CurrentClass = Cat->getClassInterface();
153      else if (ObjCImplDecl *Impl = dyn_cast<ObjCImplDecl>(DC))
154        CurrentClass = Impl->getClassInterface();
155      else if (ObjCCategoryImplDecl *CatImpl
156               = dyn_cast<ObjCCategoryImplDecl>(DC))
157        CurrentClass = CatImpl->getClassInterface();
158    }
159
160    if (CurrentClass) {
161      Diag(NewMethod->getLocation(),
162           diag::warn_related_result_type_compatibility_class)
163        << Context.getObjCInterfaceType(CurrentClass)
164        << ResultType
165        << ResultTypeRange;
166    } else {
167      Diag(NewMethod->getLocation(),
168           diag::warn_related_result_type_compatibility_protocol)
169        << ResultType
170        << ResultTypeRange;
171    }
172
173    if (ObjCMethodFamily Family = Overridden->getMethodFamily())
174      Diag(Overridden->getLocation(),
175           diag::note_related_result_type_family)
176        << /*overridden method*/ 0
177        << Family;
178    else
179      Diag(Overridden->getLocation(),
180           diag::note_related_result_type_overridden);
181  }
182
183  if ((NewMethod->hasAttr<NSReturnsRetainedAttr>() !=
184       Overridden->hasAttr<NSReturnsRetainedAttr>())) {
185    Diag(NewMethod->getLocation(),
186         getLangOpts().ObjCAutoRefCount
187             ? diag::err_nsreturns_retained_attribute_mismatch
188             : diag::warn_nsreturns_retained_attribute_mismatch)
189        << 1;
190    Diag(Overridden->getLocation(), diag::note_previous_decl) << "method";
191  }
192  if ((NewMethod->hasAttr<NSReturnsNotRetainedAttr>() !=
193       Overridden->hasAttr<NSReturnsNotRetainedAttr>())) {
194    Diag(NewMethod->getLocation(),
195         getLangOpts().ObjCAutoRefCount
196             ? diag::err_nsreturns_retained_attribute_mismatch
197             : diag::warn_nsreturns_retained_attribute_mismatch)
198        << 0;
199    Diag(Overridden->getLocation(), diag::note_previous_decl)  << "method";
200  }
201
202  ObjCMethodDecl::param_const_iterator oi = Overridden->param_begin(),
203                                       oe = Overridden->param_end();
204  for (ObjCMethodDecl::param_iterator ni = NewMethod->param_begin(),
205                                      ne = NewMethod->param_end();
206       ni != ne && oi != oe; ++ni, ++oi) {
207    const ParmVarDecl *oldDecl = (*oi);
208    ParmVarDecl *newDecl = (*ni);
209    if (newDecl->hasAttr<NSConsumedAttr>() !=
210        oldDecl->hasAttr<NSConsumedAttr>()) {
211      Diag(newDecl->getLocation(),
212           getLangOpts().ObjCAutoRefCount
213               ? diag::err_nsconsumed_attribute_mismatch
214               : diag::warn_nsconsumed_attribute_mismatch);
215      Diag(oldDecl->getLocation(), diag::note_previous_decl) << "parameter";
216    }
217
218    diagnoseNoescape(newDecl, oldDecl, *this);
219  }
220}
221
222/// Check a method declaration for compatibility with the Objective-C
223/// ARC conventions.
224bool Sema::CheckARCMethodDecl(ObjCMethodDecl *method) {
225  ObjCMethodFamily family = method->getMethodFamily();
226  switch (family) {
227  case OMF_None:
228  case OMF_finalize:
229  case OMF_retain:
230  case OMF_release:
231  case OMF_autorelease:
232  case OMF_retainCount:
233  case OMF_self:
234  case OMF_initialize:
235  case OMF_performSelector:
236    return false;
237
238  case OMF_dealloc:
239    if (!Context.hasSameType(method->getReturnType(), Context.VoidTy)) {
240      SourceRange ResultTypeRange = method->getReturnTypeSourceRange();
241      if (ResultTypeRange.isInvalid())
242        Diag(method->getLocation(), diag::err_dealloc_bad_result_type)
243            << method->getReturnType()
244            << FixItHint::CreateInsertion(method->getSelectorLoc(0), "(void)");
245      else
246        Diag(method->getLocation(), diag::err_dealloc_bad_result_type)
247            << method->getReturnType()
248            << FixItHint::CreateReplacement(ResultTypeRange, "void");
249      return true;
250    }
251    return false;
252
253  case OMF_init:
254    // If the method doesn't obey the init rules, don't bother annotating it.
255    if (checkInitMethod(method, QualType()))
256      return true;
257
258    method->addAttr(NSConsumesSelfAttr::CreateImplicit(Context));
259
260    // Don't add a second copy of this attribute, but otherwise don't
261    // let it be suppressed.
262    if (method->hasAttr<NSReturnsRetainedAttr>())
263      return false;
264    break;
265
266  case OMF_alloc:
267  case OMF_copy:
268  case OMF_mutableCopy:
269  case OMF_new:
270    if (method->hasAttr<NSReturnsRetainedAttr>() ||
271        method->hasAttr<NSReturnsNotRetainedAttr>() ||
272        method->hasAttr<NSReturnsAutoreleasedAttr>())
273      return false;
274    break;
275  }
276
277  method->addAttr(NSReturnsRetainedAttr::CreateImplicit(Context));
278  return false;
279}
280
281static void DiagnoseObjCImplementedDeprecations(Sema &S, const NamedDecl *ND,
282                                                SourceLocation ImplLoc) {
283  if (!ND)
284    return;
285  bool IsCategory = false;
286  StringRef RealizedPlatform;
287  AvailabilityResult Availability = ND->getAvailability(
288      /*Message=*/nullptr, /*EnclosingVersion=*/VersionTuple(),
289      &RealizedPlatform);
290  if (Availability != AR_Deprecated) {
291    if (isa<ObjCMethodDecl>(ND)) {
292      if (Availability != AR_Unavailable)
293        return;
294      if (RealizedPlatform.empty())
295        RealizedPlatform = S.Context.getTargetInfo().getPlatformName();
296      // Warn about implementing unavailable methods, unless the unavailable
297      // is for an app extension.
298      if (RealizedPlatform.endswith("_app_extension"))
299        return;
300      S.Diag(ImplLoc, diag::warn_unavailable_def);
301      S.Diag(ND->getLocation(), diag::note_method_declared_at)
302          << ND->getDeclName();
303      return;
304    }
305    if (const auto *CD = dyn_cast<ObjCCategoryDecl>(ND)) {
306      if (!CD->getClassInterface()->isDeprecated())
307        return;
308      ND = CD->getClassInterface();
309      IsCategory = true;
310    } else
311      return;
312  }
313  S.Diag(ImplLoc, diag::warn_deprecated_def)
314      << (isa<ObjCMethodDecl>(ND)
315              ? /*Method*/ 0
316              : isa<ObjCCategoryDecl>(ND) || IsCategory ? /*Category*/ 2
317                                                        : /*Class*/ 1);
318  if (isa<ObjCMethodDecl>(ND))
319    S.Diag(ND->getLocation(), diag::note_method_declared_at)
320        << ND->getDeclName();
321  else
322    S.Diag(ND->getLocation(), diag::note_previous_decl)
323        << (isa<ObjCCategoryDecl>(ND) ? "category" : "class");
324}
325
326/// AddAnyMethodToGlobalPool - Add any method, instance or factory to global
327/// pool.
328void Sema::AddAnyMethodToGlobalPool(Decl *D) {
329  ObjCMethodDecl *MDecl = dyn_cast_or_null<ObjCMethodDecl>(D);
330
331  // If we don't have a valid method decl, simply return.
332  if (!MDecl)
333    return;
334  if (MDecl->isInstanceMethod())
335    AddInstanceMethodToGlobalPool(MDecl, true);
336  else
337    AddFactoryMethodToGlobalPool(MDecl, true);
338}
339
340/// HasExplicitOwnershipAttr - returns true when pointer to ObjC pointer
341/// has explicit ownership attribute; false otherwise.
342static bool
343HasExplicitOwnershipAttr(Sema &S, ParmVarDecl *Param) {
344  QualType T = Param->getType();
345
346  if (const PointerType *PT = T->getAs<PointerType>()) {
347    T = PT->getPointeeType();
348  } else if (const ReferenceType *RT = T->getAs<ReferenceType>()) {
349    T = RT->getPointeeType();
350  } else {
351    return true;
352  }
353
354  // If we have a lifetime qualifier, but it's local, we must have
355  // inferred it. So, it is implicit.
356  return !T.getLocalQualifiers().hasObjCLifetime();
357}
358
359/// ActOnStartOfObjCMethodDef - This routine sets up parameters; invisible
360/// and user declared, in the method definition's AST.
361void Sema::ActOnStartOfObjCMethodDef(Scope *FnBodyScope, Decl *D) {
362  ImplicitlyRetainedSelfLocs.clear();
363  assert((getCurMethodDecl() == nullptr) && "Methodparsing confused");
364  ObjCMethodDecl *MDecl = dyn_cast_or_null<ObjCMethodDecl>(D);
365
366  PushExpressionEvaluationContext(ExprEvalContexts.back().Context);
367
368  // If we don't have a valid method decl, simply return.
369  if (!MDecl)
370    return;
371
372  QualType ResultType = MDecl->getReturnType();
373  if (!ResultType->isDependentType() && !ResultType->isVoidType() &&
374      !MDecl->isInvalidDecl() &&
375      RequireCompleteType(MDecl->getLocation(), ResultType,
376                          diag::err_func_def_incomplete_result))
377    MDecl->setInvalidDecl();
378
379  // Allow all of Sema to see that we are entering a method definition.
380  PushDeclContext(FnBodyScope, MDecl);
381  PushFunctionScope();
382
383  // Create Decl objects for each parameter, entrring them in the scope for
384  // binding to their use.
385
386  // Insert the invisible arguments, self and _cmd!
387  MDecl->createImplicitParams(Context, MDecl->getClassInterface());
388
389  PushOnScopeChains(MDecl->getSelfDecl(), FnBodyScope);
390  PushOnScopeChains(MDecl->getCmdDecl(), FnBodyScope);
391
392  // The ObjC parser requires parameter names so there's no need to check.
393  CheckParmsForFunctionDef(MDecl->parameters(),
394                           /*CheckParameterNames=*/false);
395
396  // Introduce all of the other parameters into this scope.
397  for (auto *Param : MDecl->parameters()) {
398    if (!Param->isInvalidDecl() &&
399        getLangOpts().ObjCAutoRefCount &&
400        !HasExplicitOwnershipAttr(*this, Param))
401      Diag(Param->getLocation(), diag::warn_arc_strong_pointer_objc_pointer) <<
402            Param->getType();
403
404    if (Param->getIdentifier())
405      PushOnScopeChains(Param, FnBodyScope);
406  }
407
408  // In ARC, disallow definition of retain/release/autorelease/retainCount
409  if (getLangOpts().ObjCAutoRefCount) {
410    switch (MDecl->getMethodFamily()) {
411    case OMF_retain:
412    case OMF_retainCount:
413    case OMF_release:
414    case OMF_autorelease:
415      Diag(MDecl->getLocation(), diag::err_arc_illegal_method_def)
416        << 0 << MDecl->getSelector();
417      break;
418
419    case OMF_None:
420    case OMF_dealloc:
421    case OMF_finalize:
422    case OMF_alloc:
423    case OMF_init:
424    case OMF_mutableCopy:
425    case OMF_copy:
426    case OMF_new:
427    case OMF_self:
428    case OMF_initialize:
429    case OMF_performSelector:
430      break;
431    }
432  }
433
434  // Warn on deprecated methods under -Wdeprecated-implementations,
435  // and prepare for warning on missing super calls.
436  if (ObjCInterfaceDecl *IC = MDecl->getClassInterface()) {
437    ObjCMethodDecl *IMD =
438      IC->lookupMethod(MDecl->getSelector(), MDecl->isInstanceMethod());
439
440    if (IMD) {
441      ObjCImplDecl *ImplDeclOfMethodDef =
442        dyn_cast<ObjCImplDecl>(MDecl->getDeclContext());
443      ObjCContainerDecl *ContDeclOfMethodDecl =
444        dyn_cast<ObjCContainerDecl>(IMD->getDeclContext());
445      ObjCImplDecl *ImplDeclOfMethodDecl = nullptr;
446      if (ObjCInterfaceDecl *OID = dyn_cast<ObjCInterfaceDecl>(ContDeclOfMethodDecl))
447        ImplDeclOfMethodDecl = OID->getImplementation();
448      else if (ObjCCategoryDecl *CD = dyn_cast<ObjCCategoryDecl>(ContDeclOfMethodDecl)) {
449        if (CD->IsClassExtension()) {
450          if (ObjCInterfaceDecl *OID = CD->getClassInterface())
451            ImplDeclOfMethodDecl = OID->getImplementation();
452        } else
453            ImplDeclOfMethodDecl = CD->getImplementation();
454      }
455      // No need to issue deprecated warning if deprecated mehod in class/category
456      // is being implemented in its own implementation (no overriding is involved).
457      if (!ImplDeclOfMethodDecl || ImplDeclOfMethodDecl != ImplDeclOfMethodDef)
458        DiagnoseObjCImplementedDeprecations(*this, IMD, MDecl->getLocation());
459    }
460
461    if (MDecl->getMethodFamily() == OMF_init) {
462      if (MDecl->isDesignatedInitializerForTheInterface()) {
463        getCurFunction()->ObjCIsDesignatedInit = true;
464        getCurFunction()->ObjCWarnForNoDesignatedInitChain =
465            IC->getSuperClass() != nullptr;
466      } else if (IC->hasDesignatedInitializers()) {
467        getCurFunction()->ObjCIsSecondaryInit = true;
468        getCurFunction()->ObjCWarnForNoInitDelegation = true;
469      }
470    }
471
472    // If this is "dealloc" or "finalize", set some bit here.
473    // Then in ActOnSuperMessage() (SemaExprObjC), set it back to false.
474    // Finally, in ActOnFinishFunctionBody() (SemaDecl), warn if flag is set.
475    // Only do this if the current class actually has a superclass.
476    if (const ObjCInterfaceDecl *SuperClass = IC->getSuperClass()) {
477      ObjCMethodFamily Family = MDecl->getMethodFamily();
478      if (Family == OMF_dealloc) {
479        if (!(getLangOpts().ObjCAutoRefCount ||
480              getLangOpts().getGC() == LangOptions::GCOnly))
481          getCurFunction()->ObjCShouldCallSuper = true;
482
483      } else if (Family == OMF_finalize) {
484        if (Context.getLangOpts().getGC() != LangOptions::NonGC)
485          getCurFunction()->ObjCShouldCallSuper = true;
486
487      } else {
488        const ObjCMethodDecl *SuperMethod =
489          SuperClass->lookupMethod(MDecl->getSelector(),
490                                   MDecl->isInstanceMethod());
491        getCurFunction()->ObjCShouldCallSuper =
492          (SuperMethod && SuperMethod->hasAttr<ObjCRequiresSuperAttr>());
493      }
494    }
495  }
496}
497
498namespace {
499
500// Callback to only accept typo corrections that are Objective-C classes.
501// If an ObjCInterfaceDecl* is given to the constructor, then the validation
502// function will reject corrections to that class.
503class ObjCInterfaceValidatorCCC final : public CorrectionCandidateCallback {
504 public:
505  ObjCInterfaceValidatorCCC() : CurrentIDecl(nullptr) {}
506  explicit ObjCInterfaceValidatorCCC(ObjCInterfaceDecl *IDecl)
507      : CurrentIDecl(IDecl) {}
508
509  bool ValidateCandidate(const TypoCorrection &candidate) override {
510    ObjCInterfaceDecl *ID = candidate.getCorrectionDeclAs<ObjCInterfaceDecl>();
511    return ID && !declaresSameEntity(ID, CurrentIDecl);
512  }
513
514  std::unique_ptr<CorrectionCandidateCallback> clone() override {
515    return std::make_unique<ObjCInterfaceValidatorCCC>(*this);
516  }
517
518 private:
519  ObjCInterfaceDecl *CurrentIDecl;
520};
521
522} // end anonymous namespace
523
524static void diagnoseUseOfProtocols(Sema &TheSema,
525                                   ObjCContainerDecl *CD,
526                                   ObjCProtocolDecl *const *ProtoRefs,
527                                   unsigned NumProtoRefs,
528                                   const SourceLocation *ProtoLocs) {
529  assert(ProtoRefs);
530  // Diagnose availability in the context of the ObjC container.
531  Sema::ContextRAII SavedContext(TheSema, CD);
532  for (unsigned i = 0; i < NumProtoRefs; ++i) {
533    (void)TheSema.DiagnoseUseOfDecl(ProtoRefs[i], ProtoLocs[i],
534                                    /*UnknownObjCClass=*/nullptr,
535                                    /*ObjCPropertyAccess=*/false,
536                                    /*AvoidPartialAvailabilityChecks=*/true);
537  }
538}
539
540void Sema::
541ActOnSuperClassOfClassInterface(Scope *S,
542                                SourceLocation AtInterfaceLoc,
543                                ObjCInterfaceDecl *IDecl,
544                                IdentifierInfo *ClassName,
545                                SourceLocation ClassLoc,
546                                IdentifierInfo *SuperName,
547                                SourceLocation SuperLoc,
548                                ArrayRef<ParsedType> SuperTypeArgs,
549                                SourceRange SuperTypeArgsRange) {
550  // Check if a different kind of symbol declared in this scope.
551  NamedDecl *PrevDecl = LookupSingleName(TUScope, SuperName, SuperLoc,
552                                         LookupOrdinaryName);
553
554  if (!PrevDecl) {
555    // Try to correct for a typo in the superclass name without correcting
556    // to the class we're defining.
557    ObjCInterfaceValidatorCCC CCC(IDecl);
558    if (TypoCorrection Corrected = CorrectTypo(
559            DeclarationNameInfo(SuperName, SuperLoc), LookupOrdinaryName,
560            TUScope, nullptr, CCC, CTK_ErrorRecovery)) {
561      diagnoseTypo(Corrected, PDiag(diag::err_undef_superclass_suggest)
562                   << SuperName << ClassName);
563      PrevDecl = Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>();
564    }
565  }
566
567  if (declaresSameEntity(PrevDecl, IDecl)) {
568    Diag(SuperLoc, diag::err_recursive_superclass)
569      << SuperName << ClassName << SourceRange(AtInterfaceLoc, ClassLoc);
570    IDecl->setEndOfDefinitionLoc(ClassLoc);
571  } else {
572    ObjCInterfaceDecl *SuperClassDecl =
573    dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
574    QualType SuperClassType;
575
576    // Diagnose classes that inherit from deprecated classes.
577    if (SuperClassDecl) {
578      (void)DiagnoseUseOfDecl(SuperClassDecl, SuperLoc);
579      SuperClassType = Context.getObjCInterfaceType(SuperClassDecl);
580    }
581
582    if (PrevDecl && !SuperClassDecl) {
583      // The previous declaration was not a class decl. Check if we have a
584      // typedef. If we do, get the underlying class type.
585      if (const TypedefNameDecl *TDecl =
586          dyn_cast_or_null<TypedefNameDecl>(PrevDecl)) {
587        QualType T = TDecl->getUnderlyingType();
588        if (T->isObjCObjectType()) {
589          if (NamedDecl *IDecl = T->castAs<ObjCObjectType>()->getInterface()) {
590            SuperClassDecl = dyn_cast<ObjCInterfaceDecl>(IDecl);
591            SuperClassType = Context.getTypeDeclType(TDecl);
592
593            // This handles the following case:
594            // @interface NewI @end
595            // typedef NewI DeprI __attribute__((deprecated("blah")))
596            // @interface SI : DeprI /* warn here */ @end
597            (void)DiagnoseUseOfDecl(const_cast<TypedefNameDecl*>(TDecl), SuperLoc);
598          }
599        }
600      }
601
602      // This handles the following case:
603      //
604      // typedef int SuperClass;
605      // @interface MyClass : SuperClass {} @end
606      //
607      if (!SuperClassDecl) {
608        Diag(SuperLoc, diag::err_redefinition_different_kind) << SuperName;
609        Diag(PrevDecl->getLocation(), diag::note_previous_definition);
610      }
611    }
612
613    if (!dyn_cast_or_null<TypedefNameDecl>(PrevDecl)) {
614      if (!SuperClassDecl)
615        Diag(SuperLoc, diag::err_undef_superclass)
616          << SuperName << ClassName << SourceRange(AtInterfaceLoc, ClassLoc);
617      else if (RequireCompleteType(SuperLoc,
618                                   SuperClassType,
619                                   diag::err_forward_superclass,
620                                   SuperClassDecl->getDeclName(),
621                                   ClassName,
622                                   SourceRange(AtInterfaceLoc, ClassLoc))) {
623        SuperClassDecl = nullptr;
624        SuperClassType = QualType();
625      }
626    }
627
628    if (SuperClassType.isNull()) {
629      assert(!SuperClassDecl && "Failed to set SuperClassType?");
630      return;
631    }
632
633    // Handle type arguments on the superclass.
634    TypeSourceInfo *SuperClassTInfo = nullptr;
635    if (!SuperTypeArgs.empty()) {
636      TypeResult fullSuperClassType = actOnObjCTypeArgsAndProtocolQualifiers(
637                                        S,
638                                        SuperLoc,
639                                        CreateParsedType(SuperClassType,
640                                                         nullptr),
641                                        SuperTypeArgsRange.getBegin(),
642                                        SuperTypeArgs,
643                                        SuperTypeArgsRange.getEnd(),
644                                        SourceLocation(),
645                                        { },
646                                        { },
647                                        SourceLocation());
648      if (!fullSuperClassType.isUsable())
649        return;
650
651      SuperClassType = GetTypeFromParser(fullSuperClassType.get(),
652                                         &SuperClassTInfo);
653    }
654
655    if (!SuperClassTInfo) {
656      SuperClassTInfo = Context.getTrivialTypeSourceInfo(SuperClassType,
657                                                         SuperLoc);
658    }
659
660    IDecl->setSuperClass(SuperClassTInfo);
661    IDecl->setEndOfDefinitionLoc(SuperClassTInfo->getTypeLoc().getEndLoc());
662  }
663}
664
665DeclResult Sema::actOnObjCTypeParam(Scope *S,
666                                    ObjCTypeParamVariance variance,
667                                    SourceLocation varianceLoc,
668                                    unsigned index,
669                                    IdentifierInfo *paramName,
670                                    SourceLocation paramLoc,
671                                    SourceLocation colonLoc,
672                                    ParsedType parsedTypeBound) {
673  // If there was an explicitly-provided type bound, check it.
674  TypeSourceInfo *typeBoundInfo = nullptr;
675  if (parsedTypeBound) {
676    // The type bound can be any Objective-C pointer type.
677    QualType typeBound = GetTypeFromParser(parsedTypeBound, &typeBoundInfo);
678    if (typeBound->isObjCObjectPointerType()) {
679      // okay
680    } else if (typeBound->isObjCObjectType()) {
681      // The user forgot the * on an Objective-C pointer type, e.g.,
682      // "T : NSView".
683      SourceLocation starLoc = getLocForEndOfToken(
684                                 typeBoundInfo->getTypeLoc().getEndLoc());
685      Diag(typeBoundInfo->getTypeLoc().getBeginLoc(),
686           diag::err_objc_type_param_bound_missing_pointer)
687        << typeBound << paramName
688        << FixItHint::CreateInsertion(starLoc, " *");
689
690      // Create a new type location builder so we can update the type
691      // location information we have.
692      TypeLocBuilder builder;
693      builder.pushFullCopy(typeBoundInfo->getTypeLoc());
694
695      // Create the Objective-C pointer type.
696      typeBound = Context.getObjCObjectPointerType(typeBound);
697      ObjCObjectPointerTypeLoc newT
698        = builder.push<ObjCObjectPointerTypeLoc>(typeBound);
699      newT.setStarLoc(starLoc);
700
701      // Form the new type source information.
702      typeBoundInfo = builder.getTypeSourceInfo(Context, typeBound);
703    } else {
704      // Not a valid type bound.
705      Diag(typeBoundInfo->getTypeLoc().getBeginLoc(),
706           diag::err_objc_type_param_bound_nonobject)
707        << typeBound << paramName;
708
709      // Forget the bound; we'll default to id later.
710      typeBoundInfo = nullptr;
711    }
712
713    // Type bounds cannot have qualifiers (even indirectly) or explicit
714    // nullability.
715    if (typeBoundInfo) {
716      QualType typeBound = typeBoundInfo->getType();
717      TypeLoc qual = typeBoundInfo->getTypeLoc().findExplicitQualifierLoc();
718      if (qual || typeBound.hasQualifiers()) {
719        bool diagnosed = false;
720        SourceRange rangeToRemove;
721        if (qual) {
722          if (auto attr = qual.getAs<AttributedTypeLoc>()) {
723            rangeToRemove = attr.getLocalSourceRange();
724            if (attr.getTypePtr()->getImmediateNullability()) {
725              Diag(attr.getBeginLoc(),
726                   diag::err_objc_type_param_bound_explicit_nullability)
727                  << paramName << typeBound
728                  << FixItHint::CreateRemoval(rangeToRemove);
729              diagnosed = true;
730            }
731          }
732        }
733
734        if (!diagnosed) {
735          Diag(qual ? qual.getBeginLoc()
736                    : typeBoundInfo->getTypeLoc().getBeginLoc(),
737               diag::err_objc_type_param_bound_qualified)
738              << paramName << typeBound
739              << typeBound.getQualifiers().getAsString()
740              << FixItHint::CreateRemoval(rangeToRemove);
741        }
742
743        // If the type bound has qualifiers other than CVR, we need to strip
744        // them or we'll probably assert later when trying to apply new
745        // qualifiers.
746        Qualifiers quals = typeBound.getQualifiers();
747        quals.removeCVRQualifiers();
748        if (!quals.empty()) {
749          typeBoundInfo =
750             Context.getTrivialTypeSourceInfo(typeBound.getUnqualifiedType());
751        }
752      }
753    }
754  }
755
756  // If there was no explicit type bound (or we removed it due to an error),
757  // use 'id' instead.
758  if (!typeBoundInfo) {
759    colonLoc = SourceLocation();
760    typeBoundInfo = Context.getTrivialTypeSourceInfo(Context.getObjCIdType());
761  }
762
763  // Create the type parameter.
764  return ObjCTypeParamDecl::Create(Context, CurContext, variance, varianceLoc,
765                                   index, paramLoc, paramName, colonLoc,
766                                   typeBoundInfo);
767}
768
769ObjCTypeParamList *Sema::actOnObjCTypeParamList(Scope *S,
770                                                SourceLocation lAngleLoc,
771                                                ArrayRef<Decl *> typeParamsIn,
772                                                SourceLocation rAngleLoc) {
773  // We know that the array only contains Objective-C type parameters.
774  ArrayRef<ObjCTypeParamDecl *>
775    typeParams(
776      reinterpret_cast<ObjCTypeParamDecl * const *>(typeParamsIn.data()),
777      typeParamsIn.size());
778
779  // Diagnose redeclarations of type parameters.
780  // We do this now because Objective-C type parameters aren't pushed into
781  // scope until later (after the instance variable block), but we want the
782  // diagnostics to occur right after we parse the type parameter list.
783  llvm::SmallDenseMap<IdentifierInfo *, ObjCTypeParamDecl *> knownParams;
784  for (auto typeParam : typeParams) {
785    auto known = knownParams.find(typeParam->getIdentifier());
786    if (known != knownParams.end()) {
787      Diag(typeParam->getLocation(), diag::err_objc_type_param_redecl)
788        << typeParam->getIdentifier()
789        << SourceRange(known->second->getLocation());
790
791      typeParam->setInvalidDecl();
792    } else {
793      knownParams.insert(std::make_pair(typeParam->getIdentifier(), typeParam));
794
795      // Push the type parameter into scope.
796      PushOnScopeChains(typeParam, S, /*AddToContext=*/false);
797    }
798  }
799
800  // Create the parameter list.
801  return ObjCTypeParamList::create(Context, lAngleLoc, typeParams, rAngleLoc);
802}
803
804void Sema::popObjCTypeParamList(Scope *S, ObjCTypeParamList *typeParamList) {
805  for (auto typeParam : *typeParamList) {
806    if (!typeParam->isInvalidDecl()) {
807      S->RemoveDecl(typeParam);
808      IdResolver.RemoveDecl(typeParam);
809    }
810  }
811}
812
813namespace {
814  /// The context in which an Objective-C type parameter list occurs, for use
815  /// in diagnostics.
816  enum class TypeParamListContext {
817    ForwardDeclaration,
818    Definition,
819    Category,
820    Extension
821  };
822} // end anonymous namespace
823
824/// Check consistency between two Objective-C type parameter lists, e.g.,
825/// between a category/extension and an \@interface or between an \@class and an
826/// \@interface.
827static bool checkTypeParamListConsistency(Sema &S,
828                                          ObjCTypeParamList *prevTypeParams,
829                                          ObjCTypeParamList *newTypeParams,
830                                          TypeParamListContext newContext) {
831  // If the sizes don't match, complain about that.
832  if (prevTypeParams->size() != newTypeParams->size()) {
833    SourceLocation diagLoc;
834    if (newTypeParams->size() > prevTypeParams->size()) {
835      diagLoc = newTypeParams->begin()[prevTypeParams->size()]->getLocation();
836    } else {
837      diagLoc = S.getLocForEndOfToken(newTypeParams->back()->getEndLoc());
838    }
839
840    S.Diag(diagLoc, diag::err_objc_type_param_arity_mismatch)
841      << static_cast<unsigned>(newContext)
842      << (newTypeParams->size() > prevTypeParams->size())
843      << prevTypeParams->size()
844      << newTypeParams->size();
845
846    return true;
847  }
848
849  // Match up the type parameters.
850  for (unsigned i = 0, n = prevTypeParams->size(); i != n; ++i) {
851    ObjCTypeParamDecl *prevTypeParam = prevTypeParams->begin()[i];
852    ObjCTypeParamDecl *newTypeParam = newTypeParams->begin()[i];
853
854    // Check for consistency of the variance.
855    if (newTypeParam->getVariance() != prevTypeParam->getVariance()) {
856      if (newTypeParam->getVariance() == ObjCTypeParamVariance::Invariant &&
857          newContext != TypeParamListContext::Definition) {
858        // When the new type parameter is invariant and is not part
859        // of the definition, just propagate the variance.
860        newTypeParam->setVariance(prevTypeParam->getVariance());
861      } else if (prevTypeParam->getVariance()
862                   == ObjCTypeParamVariance::Invariant &&
863                 !(isa<ObjCInterfaceDecl>(prevTypeParam->getDeclContext()) &&
864                   cast<ObjCInterfaceDecl>(prevTypeParam->getDeclContext())
865                     ->getDefinition() == prevTypeParam->getDeclContext())) {
866        // When the old parameter is invariant and was not part of the
867        // definition, just ignore the difference because it doesn't
868        // matter.
869      } else {
870        {
871          // Diagnose the conflict and update the second declaration.
872          SourceLocation diagLoc = newTypeParam->getVarianceLoc();
873          if (diagLoc.isInvalid())
874            diagLoc = newTypeParam->getBeginLoc();
875
876          auto diag = S.Diag(diagLoc,
877                             diag::err_objc_type_param_variance_conflict)
878                        << static_cast<unsigned>(newTypeParam->getVariance())
879                        << newTypeParam->getDeclName()
880                        << static_cast<unsigned>(prevTypeParam->getVariance())
881                        << prevTypeParam->getDeclName();
882          switch (prevTypeParam->getVariance()) {
883          case ObjCTypeParamVariance::Invariant:
884            diag << FixItHint::CreateRemoval(newTypeParam->getVarianceLoc());
885            break;
886
887          case ObjCTypeParamVariance::Covariant:
888          case ObjCTypeParamVariance::Contravariant: {
889            StringRef newVarianceStr
890               = prevTypeParam->getVariance() == ObjCTypeParamVariance::Covariant
891                   ? "__covariant"
892                   : "__contravariant";
893            if (newTypeParam->getVariance()
894                  == ObjCTypeParamVariance::Invariant) {
895              diag << FixItHint::CreateInsertion(newTypeParam->getBeginLoc(),
896                                                 (newVarianceStr + " ").str());
897            } else {
898              diag << FixItHint::CreateReplacement(newTypeParam->getVarianceLoc(),
899                                               newVarianceStr);
900            }
901          }
902          }
903        }
904
905        S.Diag(prevTypeParam->getLocation(), diag::note_objc_type_param_here)
906          << prevTypeParam->getDeclName();
907
908        // Override the variance.
909        newTypeParam->setVariance(prevTypeParam->getVariance());
910      }
911    }
912
913    // If the bound types match, there's nothing to do.
914    if (S.Context.hasSameType(prevTypeParam->getUnderlyingType(),
915                              newTypeParam->getUnderlyingType()))
916      continue;
917
918    // If the new type parameter's bound was explicit, complain about it being
919    // different from the original.
920    if (newTypeParam->hasExplicitBound()) {
921      SourceRange newBoundRange = newTypeParam->getTypeSourceInfo()
922                                    ->getTypeLoc().getSourceRange();
923      S.Diag(newBoundRange.getBegin(), diag::err_objc_type_param_bound_conflict)
924        << newTypeParam->getUnderlyingType()
925        << newTypeParam->getDeclName()
926        << prevTypeParam->hasExplicitBound()
927        << prevTypeParam->getUnderlyingType()
928        << (newTypeParam->getDeclName() == prevTypeParam->getDeclName())
929        << prevTypeParam->getDeclName()
930        << FixItHint::CreateReplacement(
931             newBoundRange,
932             prevTypeParam->getUnderlyingType().getAsString(
933               S.Context.getPrintingPolicy()));
934
935      S.Diag(prevTypeParam->getLocation(), diag::note_objc_type_param_here)
936        << prevTypeParam->getDeclName();
937
938      // Override the new type parameter's bound type with the previous type,
939      // so that it's consistent.
940      newTypeParam->setTypeSourceInfo(
941        S.Context.getTrivialTypeSourceInfo(prevTypeParam->getUnderlyingType()));
942      continue;
943    }
944
945    // The new type parameter got the implicit bound of 'id'. That's okay for
946    // categories and extensions (overwrite it later), but not for forward
947    // declarations and @interfaces, because those must be standalone.
948    if (newContext == TypeParamListContext::ForwardDeclaration ||
949        newContext == TypeParamListContext::Definition) {
950      // Diagnose this problem for forward declarations and definitions.
951      SourceLocation insertionLoc
952        = S.getLocForEndOfToken(newTypeParam->getLocation());
953      std::string newCode
954        = " : " + prevTypeParam->getUnderlyingType().getAsString(
955                    S.Context.getPrintingPolicy());
956      S.Diag(newTypeParam->getLocation(),
957             diag::err_objc_type_param_bound_missing)
958        << prevTypeParam->getUnderlyingType()
959        << newTypeParam->getDeclName()
960        << (newContext == TypeParamListContext::ForwardDeclaration)
961        << FixItHint::CreateInsertion(insertionLoc, newCode);
962
963      S.Diag(prevTypeParam->getLocation(), diag::note_objc_type_param_here)
964        << prevTypeParam->getDeclName();
965    }
966
967    // Update the new type parameter's bound to match the previous one.
968    newTypeParam->setTypeSourceInfo(
969      S.Context.getTrivialTypeSourceInfo(prevTypeParam->getUnderlyingType()));
970  }
971
972  return false;
973}
974
975Decl *Sema::ActOnStartClassInterface(
976    Scope *S, SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
977    SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
978    IdentifierInfo *SuperName, SourceLocation SuperLoc,
979    ArrayRef<ParsedType> SuperTypeArgs, SourceRange SuperTypeArgsRange,
980    Decl *const *ProtoRefs, unsigned NumProtoRefs,
981    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
982    const ParsedAttributesView &AttrList) {
983  assert(ClassName && "Missing class identifier");
984
985  // Check for another declaration kind with the same name.
986  NamedDecl *PrevDecl =
987      LookupSingleName(TUScope, ClassName, ClassLoc, LookupOrdinaryName,
988                       forRedeclarationInCurContext());
989
990  if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
991    Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
992    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
993  }
994
995  // Create a declaration to describe this @interface.
996  ObjCInterfaceDecl* PrevIDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
997
998  if (PrevIDecl && PrevIDecl->getIdentifier() != ClassName) {
999    // A previous decl with a different name is because of
1000    // @compatibility_alias, for example:
1001    // \code
1002    //   @class NewImage;
1003    //   @compatibility_alias OldImage NewImage;
1004    // \endcode
1005    // A lookup for 'OldImage' will return the 'NewImage' decl.
1006    //
1007    // In such a case use the real declaration name, instead of the alias one,
1008    // otherwise we will break IdentifierResolver and redecls-chain invariants.
1009    // FIXME: If necessary, add a bit to indicate that this ObjCInterfaceDecl
1010    // has been aliased.
1011    ClassName = PrevIDecl->getIdentifier();
1012  }
1013
1014  // If there was a forward declaration with type parameters, check
1015  // for consistency.
1016  if (PrevIDecl) {
1017    if (ObjCTypeParamList *prevTypeParamList = PrevIDecl->getTypeParamList()) {
1018      if (typeParamList) {
1019        // Both have type parameter lists; check for consistency.
1020        if (checkTypeParamListConsistency(*this, prevTypeParamList,
1021                                          typeParamList,
1022                                          TypeParamListContext::Definition)) {
1023          typeParamList = nullptr;
1024        }
1025      } else {
1026        Diag(ClassLoc, diag::err_objc_parameterized_forward_class_first)
1027          << ClassName;
1028        Diag(prevTypeParamList->getLAngleLoc(), diag::note_previous_decl)
1029          << ClassName;
1030
1031        // Clone the type parameter list.
1032        SmallVector<ObjCTypeParamDecl *, 4> clonedTypeParams;
1033        for (auto typeParam : *prevTypeParamList) {
1034          clonedTypeParams.push_back(
1035            ObjCTypeParamDecl::Create(
1036              Context,
1037              CurContext,
1038              typeParam->getVariance(),
1039              SourceLocation(),
1040              typeParam->getIndex(),
1041              SourceLocation(),
1042              typeParam->getIdentifier(),
1043              SourceLocation(),
1044              Context.getTrivialTypeSourceInfo(typeParam->getUnderlyingType())));
1045        }
1046
1047        typeParamList = ObjCTypeParamList::create(Context,
1048                                                  SourceLocation(),
1049                                                  clonedTypeParams,
1050                                                  SourceLocation());
1051      }
1052    }
1053  }
1054
1055  ObjCInterfaceDecl *IDecl
1056    = ObjCInterfaceDecl::Create(Context, CurContext, AtInterfaceLoc, ClassName,
1057                                typeParamList, PrevIDecl, ClassLoc);
1058  if (PrevIDecl) {
1059    // Class already seen. Was it a definition?
1060    if (ObjCInterfaceDecl *Def = PrevIDecl->getDefinition()) {
1061      Diag(AtInterfaceLoc, diag::err_duplicate_class_def)
1062        << PrevIDecl->getDeclName();
1063      Diag(Def->getLocation(), diag::note_previous_definition);
1064      IDecl->setInvalidDecl();
1065    }
1066  }
1067
1068  ProcessDeclAttributeList(TUScope, IDecl, AttrList);
1069  AddPragmaAttributes(TUScope, IDecl);
1070  PushOnScopeChains(IDecl, TUScope);
1071
1072  // Start the definition of this class. If we're in a redefinition case, there
1073  // may already be a definition, so we'll end up adding to it.
1074  if (!IDecl->hasDefinition())
1075    IDecl->startDefinition();
1076
1077  if (SuperName) {
1078    // Diagnose availability in the context of the @interface.
1079    ContextRAII SavedContext(*this, IDecl);
1080
1081    ActOnSuperClassOfClassInterface(S, AtInterfaceLoc, IDecl,
1082                                    ClassName, ClassLoc,
1083                                    SuperName, SuperLoc, SuperTypeArgs,
1084                                    SuperTypeArgsRange);
1085  } else { // we have a root class.
1086    IDecl->setEndOfDefinitionLoc(ClassLoc);
1087  }
1088
1089  // Check then save referenced protocols.
1090  if (NumProtoRefs) {
1091    diagnoseUseOfProtocols(*this, IDecl, (ObjCProtocolDecl*const*)ProtoRefs,
1092                           NumProtoRefs, ProtoLocs);
1093    IDecl->setProtocolList((ObjCProtocolDecl*const*)ProtoRefs, NumProtoRefs,
1094                           ProtoLocs, Context);
1095    IDecl->setEndOfDefinitionLoc(EndProtoLoc);
1096  }
1097
1098  CheckObjCDeclScope(IDecl);
1099  return ActOnObjCContainerStartDefinition(IDecl);
1100}
1101
1102/// ActOnTypedefedProtocols - this action finds protocol list as part of the
1103/// typedef'ed use for a qualified super class and adds them to the list
1104/// of the protocols.
1105void Sema::ActOnTypedefedProtocols(SmallVectorImpl<Decl *> &ProtocolRefs,
1106                                  SmallVectorImpl<SourceLocation> &ProtocolLocs,
1107                                   IdentifierInfo *SuperName,
1108                                   SourceLocation SuperLoc) {
1109  if (!SuperName)
1110    return;
1111  NamedDecl* IDecl = LookupSingleName(TUScope, SuperName, SuperLoc,
1112                                      LookupOrdinaryName);
1113  if (!IDecl)
1114    return;
1115
1116  if (const TypedefNameDecl *TDecl = dyn_cast_or_null<TypedefNameDecl>(IDecl)) {
1117    QualType T = TDecl->getUnderlyingType();
1118    if (T->isObjCObjectType())
1119      if (const ObjCObjectType *OPT = T->getAs<ObjCObjectType>()) {
1120        ProtocolRefs.append(OPT->qual_begin(), OPT->qual_end());
1121        // FIXME: Consider whether this should be an invalid loc since the loc
1122        // is not actually pointing to a protocol name reference but to the
1123        // typedef reference. Note that the base class name loc is also pointing
1124        // at the typedef.
1125        ProtocolLocs.append(OPT->getNumProtocols(), SuperLoc);
1126      }
1127  }
1128}
1129
1130/// ActOnCompatibilityAlias - this action is called after complete parsing of
1131/// a \@compatibility_alias declaration. It sets up the alias relationships.
1132Decl *Sema::ActOnCompatibilityAlias(SourceLocation AtLoc,
1133                                    IdentifierInfo *AliasName,
1134                                    SourceLocation AliasLocation,
1135                                    IdentifierInfo *ClassName,
1136                                    SourceLocation ClassLocation) {
1137  // Look for previous declaration of alias name
1138  NamedDecl *ADecl =
1139      LookupSingleName(TUScope, AliasName, AliasLocation, LookupOrdinaryName,
1140                       forRedeclarationInCurContext());
1141  if (ADecl) {
1142    Diag(AliasLocation, diag::err_conflicting_aliasing_type) << AliasName;
1143    Diag(ADecl->getLocation(), diag::note_previous_declaration);
1144    return nullptr;
1145  }
1146  // Check for class declaration
1147  NamedDecl *CDeclU =
1148      LookupSingleName(TUScope, ClassName, ClassLocation, LookupOrdinaryName,
1149                       forRedeclarationInCurContext());
1150  if (const TypedefNameDecl *TDecl =
1151        dyn_cast_or_null<TypedefNameDecl>(CDeclU)) {
1152    QualType T = TDecl->getUnderlyingType();
1153    if (T->isObjCObjectType()) {
1154      if (NamedDecl *IDecl = T->castAs<ObjCObjectType>()->getInterface()) {
1155        ClassName = IDecl->getIdentifier();
1156        CDeclU = LookupSingleName(TUScope, ClassName, ClassLocation,
1157                                  LookupOrdinaryName,
1158                                  forRedeclarationInCurContext());
1159      }
1160    }
1161  }
1162  ObjCInterfaceDecl *CDecl = dyn_cast_or_null<ObjCInterfaceDecl>(CDeclU);
1163  if (!CDecl) {
1164    Diag(ClassLocation, diag::warn_undef_interface) << ClassName;
1165    if (CDeclU)
1166      Diag(CDeclU->getLocation(), diag::note_previous_declaration);
1167    return nullptr;
1168  }
1169
1170  // Everything checked out, instantiate a new alias declaration AST.
1171  ObjCCompatibleAliasDecl *AliasDecl =
1172    ObjCCompatibleAliasDecl::Create(Context, CurContext, AtLoc, AliasName, CDecl);
1173
1174  if (!CheckObjCDeclScope(AliasDecl))
1175    PushOnScopeChains(AliasDecl, TUScope);
1176
1177  return AliasDecl;
1178}
1179
1180bool Sema::CheckForwardProtocolDeclarationForCircularDependency(
1181  IdentifierInfo *PName,
1182  SourceLocation &Ploc, SourceLocation PrevLoc,
1183  const ObjCList<ObjCProtocolDecl> &PList) {
1184
1185  bool res = false;
1186  for (ObjCList<ObjCProtocolDecl>::iterator I = PList.begin(),
1187       E = PList.end(); I != E; ++I) {
1188    if (ObjCProtocolDecl *PDecl = LookupProtocol((*I)->getIdentifier(),
1189                                                 Ploc)) {
1190      if (PDecl->getIdentifier() == PName) {
1191        Diag(Ploc, diag::err_protocol_has_circular_dependency);
1192        Diag(PrevLoc, diag::note_previous_definition);
1193        res = true;
1194      }
1195
1196      if (!PDecl->hasDefinition())
1197        continue;
1198
1199      if (CheckForwardProtocolDeclarationForCircularDependency(PName, Ploc,
1200            PDecl->getLocation(), PDecl->getReferencedProtocols()))
1201        res = true;
1202    }
1203  }
1204  return res;
1205}
1206
1207Decl *Sema::ActOnStartProtocolInterface(
1208    SourceLocation AtProtoInterfaceLoc, IdentifierInfo *ProtocolName,
1209    SourceLocation ProtocolLoc, Decl *const *ProtoRefs, unsigned NumProtoRefs,
1210    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
1211    const ParsedAttributesView &AttrList) {
1212  bool err = false;
1213  // FIXME: Deal with AttrList.
1214  assert(ProtocolName && "Missing protocol identifier");
1215  ObjCProtocolDecl *PrevDecl = LookupProtocol(ProtocolName, ProtocolLoc,
1216                                              forRedeclarationInCurContext());
1217  ObjCProtocolDecl *PDecl = nullptr;
1218  if (ObjCProtocolDecl *Def = PrevDecl? PrevDecl->getDefinition() : nullptr) {
1219    // If we already have a definition, complain.
1220    Diag(ProtocolLoc, diag::warn_duplicate_protocol_def) << ProtocolName;
1221    Diag(Def->getLocation(), diag::note_previous_definition);
1222
1223    // Create a new protocol that is completely distinct from previous
1224    // declarations, and do not make this protocol available for name lookup.
1225    // That way, we'll end up completely ignoring the duplicate.
1226    // FIXME: Can we turn this into an error?
1227    PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
1228                                     ProtocolLoc, AtProtoInterfaceLoc,
1229                                     /*PrevDecl=*/nullptr);
1230
1231    // If we are using modules, add the decl to the context in order to
1232    // serialize something meaningful.
1233    if (getLangOpts().Modules)
1234      PushOnScopeChains(PDecl, TUScope);
1235    PDecl->startDefinition();
1236  } else {
1237    if (PrevDecl) {
1238      // Check for circular dependencies among protocol declarations. This can
1239      // only happen if this protocol was forward-declared.
1240      ObjCList<ObjCProtocolDecl> PList;
1241      PList.set((ObjCProtocolDecl *const*)ProtoRefs, NumProtoRefs, Context);
1242      err = CheckForwardProtocolDeclarationForCircularDependency(
1243              ProtocolName, ProtocolLoc, PrevDecl->getLocation(), PList);
1244    }
1245
1246    // Create the new declaration.
1247    PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
1248                                     ProtocolLoc, AtProtoInterfaceLoc,
1249                                     /*PrevDecl=*/PrevDecl);
1250
1251    PushOnScopeChains(PDecl, TUScope);
1252    PDecl->startDefinition();
1253  }
1254
1255  ProcessDeclAttributeList(TUScope, PDecl, AttrList);
1256  AddPragmaAttributes(TUScope, PDecl);
1257
1258  // Merge attributes from previous declarations.
1259  if (PrevDecl)
1260    mergeDeclAttributes(PDecl, PrevDecl);
1261
1262  if (!err && NumProtoRefs ) {
1263    /// Check then save referenced protocols.
1264    diagnoseUseOfProtocols(*this, PDecl, (ObjCProtocolDecl*const*)ProtoRefs,
1265                           NumProtoRefs, ProtoLocs);
1266    PDecl->setProtocolList((ObjCProtocolDecl*const*)ProtoRefs, NumProtoRefs,
1267                           ProtoLocs, Context);
1268  }
1269
1270  CheckObjCDeclScope(PDecl);
1271  return ActOnObjCContainerStartDefinition(PDecl);
1272}
1273
1274static bool NestedProtocolHasNoDefinition(ObjCProtocolDecl *PDecl,
1275                                          ObjCProtocolDecl *&UndefinedProtocol) {
1276  if (!PDecl->hasDefinition() || PDecl->getDefinition()->isHidden()) {
1277    UndefinedProtocol = PDecl;
1278    return true;
1279  }
1280
1281  for (auto *PI : PDecl->protocols())
1282    if (NestedProtocolHasNoDefinition(PI, UndefinedProtocol)) {
1283      UndefinedProtocol = PI;
1284      return true;
1285    }
1286  return false;
1287}
1288
1289/// FindProtocolDeclaration - This routine looks up protocols and
1290/// issues an error if they are not declared. It returns list of
1291/// protocol declarations in its 'Protocols' argument.
1292void
1293Sema::FindProtocolDeclaration(bool WarnOnDeclarations, bool ForObjCContainer,
1294                              ArrayRef<IdentifierLocPair> ProtocolId,
1295                              SmallVectorImpl<Decl *> &Protocols) {
1296  for (const IdentifierLocPair &Pair : ProtocolId) {
1297    ObjCProtocolDecl *PDecl = LookupProtocol(Pair.first, Pair.second);
1298    if (!PDecl) {
1299      DeclFilterCCC<ObjCProtocolDecl> CCC{};
1300      TypoCorrection Corrected = CorrectTypo(
1301          DeclarationNameInfo(Pair.first, Pair.second), LookupObjCProtocolName,
1302          TUScope, nullptr, CCC, CTK_ErrorRecovery);
1303      if ((PDecl = Corrected.getCorrectionDeclAs<ObjCProtocolDecl>()))
1304        diagnoseTypo(Corrected, PDiag(diag::err_undeclared_protocol_suggest)
1305                                    << Pair.first);
1306    }
1307
1308    if (!PDecl) {
1309      Diag(Pair.second, diag::err_undeclared_protocol) << Pair.first;
1310      continue;
1311    }
1312    // If this is a forward protocol declaration, get its definition.
1313    if (!PDecl->isThisDeclarationADefinition() && PDecl->getDefinition())
1314      PDecl = PDecl->getDefinition();
1315
1316    // For an objc container, delay protocol reference checking until after we
1317    // can set the objc decl as the availability context, otherwise check now.
1318    if (!ForObjCContainer) {
1319      (void)DiagnoseUseOfDecl(PDecl, Pair.second);
1320    }
1321
1322    // If this is a forward declaration and we are supposed to warn in this
1323    // case, do it.
1324    // FIXME: Recover nicely in the hidden case.
1325    ObjCProtocolDecl *UndefinedProtocol;
1326
1327    if (WarnOnDeclarations &&
1328        NestedProtocolHasNoDefinition(PDecl, UndefinedProtocol)) {
1329      Diag(Pair.second, diag::warn_undef_protocolref) << Pair.first;
1330      Diag(UndefinedProtocol->getLocation(), diag::note_protocol_decl_undefined)
1331        << UndefinedProtocol;
1332    }
1333    Protocols.push_back(PDecl);
1334  }
1335}
1336
1337namespace {
1338// Callback to only accept typo corrections that are either
1339// Objective-C protocols or valid Objective-C type arguments.
1340class ObjCTypeArgOrProtocolValidatorCCC final
1341    : public CorrectionCandidateCallback {
1342  ASTContext &Context;
1343  Sema::LookupNameKind LookupKind;
1344 public:
1345  ObjCTypeArgOrProtocolValidatorCCC(ASTContext &context,
1346                                    Sema::LookupNameKind lookupKind)
1347    : Context(context), LookupKind(lookupKind) { }
1348
1349  bool ValidateCandidate(const TypoCorrection &candidate) override {
1350    // If we're allowed to find protocols and we have a protocol, accept it.
1351    if (LookupKind != Sema::LookupOrdinaryName) {
1352      if (candidate.getCorrectionDeclAs<ObjCProtocolDecl>())
1353        return true;
1354    }
1355
1356    // If we're allowed to find type names and we have one, accept it.
1357    if (LookupKind != Sema::LookupObjCProtocolName) {
1358      // If we have a type declaration, we might accept this result.
1359      if (auto typeDecl = candidate.getCorrectionDeclAs<TypeDecl>()) {
1360        // If we found a tag declaration outside of C++, skip it. This
1361        // can happy because we look for any name when there is no
1362        // bias to protocol or type names.
1363        if (isa<RecordDecl>(typeDecl) && !Context.getLangOpts().CPlusPlus)
1364          return false;
1365
1366        // Make sure the type is something we would accept as a type
1367        // argument.
1368        auto type = Context.getTypeDeclType(typeDecl);
1369        if (type->isObjCObjectPointerType() ||
1370            type->isBlockPointerType() ||
1371            type->isDependentType() ||
1372            type->isObjCObjectType())
1373          return true;
1374
1375        return false;
1376      }
1377
1378      // If we have an Objective-C class type, accept it; there will
1379      // be another fix to add the '*'.
1380      if (candidate.getCorrectionDeclAs<ObjCInterfaceDecl>())
1381        return true;
1382
1383      return false;
1384    }
1385
1386    return false;
1387  }
1388
1389  std::unique_ptr<CorrectionCandidateCallback> clone() override {
1390    return std::make_unique<ObjCTypeArgOrProtocolValidatorCCC>(*this);
1391  }
1392};
1393} // end anonymous namespace
1394
1395void Sema::DiagnoseTypeArgsAndProtocols(IdentifierInfo *ProtocolId,
1396                                        SourceLocation ProtocolLoc,
1397                                        IdentifierInfo *TypeArgId,
1398                                        SourceLocation TypeArgLoc,
1399                                        bool SelectProtocolFirst) {
1400  Diag(TypeArgLoc, diag::err_objc_type_args_and_protocols)
1401      << SelectProtocolFirst << TypeArgId << ProtocolId
1402      << SourceRange(ProtocolLoc);
1403}
1404
1405void Sema::actOnObjCTypeArgsOrProtocolQualifiers(
1406       Scope *S,
1407       ParsedType baseType,
1408       SourceLocation lAngleLoc,
1409       ArrayRef<IdentifierInfo *> identifiers,
1410       ArrayRef<SourceLocation> identifierLocs,
1411       SourceLocation rAngleLoc,
1412       SourceLocation &typeArgsLAngleLoc,
1413       SmallVectorImpl<ParsedType> &typeArgs,
1414       SourceLocation &typeArgsRAngleLoc,
1415       SourceLocation &protocolLAngleLoc,
1416       SmallVectorImpl<Decl *> &protocols,
1417       SourceLocation &protocolRAngleLoc,
1418       bool warnOnIncompleteProtocols) {
1419  // Local function that updates the declaration specifiers with
1420  // protocol information.
1421  unsigned numProtocolsResolved = 0;
1422  auto resolvedAsProtocols = [&] {
1423    assert(numProtocolsResolved == identifiers.size() && "Unresolved protocols");
1424
1425    // Determine whether the base type is a parameterized class, in
1426    // which case we want to warn about typos such as
1427    // "NSArray<NSObject>" (that should be NSArray<NSObject *>).
1428    ObjCInterfaceDecl *baseClass = nullptr;
1429    QualType base = GetTypeFromParser(baseType, nullptr);
1430    bool allAreTypeNames = false;
1431    SourceLocation firstClassNameLoc;
1432    if (!base.isNull()) {
1433      if (const auto *objcObjectType = base->getAs<ObjCObjectType>()) {
1434        baseClass = objcObjectType->getInterface();
1435        if (baseClass) {
1436          if (auto typeParams = baseClass->getTypeParamList()) {
1437            if (typeParams->size() == numProtocolsResolved) {
1438              // Note that we should be looking for type names, too.
1439              allAreTypeNames = true;
1440            }
1441          }
1442        }
1443      }
1444    }
1445
1446    for (unsigned i = 0, n = protocols.size(); i != n; ++i) {
1447      ObjCProtocolDecl *&proto
1448        = reinterpret_cast<ObjCProtocolDecl *&>(protocols[i]);
1449      // For an objc container, delay protocol reference checking until after we
1450      // can set the objc decl as the availability context, otherwise check now.
1451      if (!warnOnIncompleteProtocols) {
1452        (void)DiagnoseUseOfDecl(proto, identifierLocs[i]);
1453      }
1454
1455      // If this is a forward protocol declaration, get its definition.
1456      if (!proto->isThisDeclarationADefinition() && proto->getDefinition())
1457        proto = proto->getDefinition();
1458
1459      // If this is a forward declaration and we are supposed to warn in this
1460      // case, do it.
1461      // FIXME: Recover nicely in the hidden case.
1462      ObjCProtocolDecl *forwardDecl = nullptr;
1463      if (warnOnIncompleteProtocols &&
1464          NestedProtocolHasNoDefinition(proto, forwardDecl)) {
1465        Diag(identifierLocs[i], diag::warn_undef_protocolref)
1466          << proto->getDeclName();
1467        Diag(forwardDecl->getLocation(), diag::note_protocol_decl_undefined)
1468          << forwardDecl;
1469      }
1470
1471      // If everything this far has been a type name (and we care
1472      // about such things), check whether this name refers to a type
1473      // as well.
1474      if (allAreTypeNames) {
1475        if (auto *decl = LookupSingleName(S, identifiers[i], identifierLocs[i],
1476                                          LookupOrdinaryName)) {
1477          if (isa<ObjCInterfaceDecl>(decl)) {
1478            if (firstClassNameLoc.isInvalid())
1479              firstClassNameLoc = identifierLocs[i];
1480          } else if (!isa<TypeDecl>(decl)) {
1481            // Not a type.
1482            allAreTypeNames = false;
1483          }
1484        } else {
1485          allAreTypeNames = false;
1486        }
1487      }
1488    }
1489
1490    // All of the protocols listed also have type names, and at least
1491    // one is an Objective-C class name. Check whether all of the
1492    // protocol conformances are declared by the base class itself, in
1493    // which case we warn.
1494    if (allAreTypeNames && firstClassNameLoc.isValid()) {
1495      llvm::SmallPtrSet<ObjCProtocolDecl*, 8> knownProtocols;
1496      Context.CollectInheritedProtocols(baseClass, knownProtocols);
1497      bool allProtocolsDeclared = true;
1498      for (auto proto : protocols) {
1499        if (knownProtocols.count(static_cast<ObjCProtocolDecl *>(proto)) == 0) {
1500          allProtocolsDeclared = false;
1501          break;
1502        }
1503      }
1504
1505      if (allProtocolsDeclared) {
1506        Diag(firstClassNameLoc, diag::warn_objc_redundant_qualified_class_type)
1507          << baseClass->getDeclName() << SourceRange(lAngleLoc, rAngleLoc)
1508          << FixItHint::CreateInsertion(getLocForEndOfToken(firstClassNameLoc),
1509                                        " *");
1510      }
1511    }
1512
1513    protocolLAngleLoc = lAngleLoc;
1514    protocolRAngleLoc = rAngleLoc;
1515    assert(protocols.size() == identifierLocs.size());
1516  };
1517
1518  // Attempt to resolve all of the identifiers as protocols.
1519  for (unsigned i = 0, n = identifiers.size(); i != n; ++i) {
1520    ObjCProtocolDecl *proto = LookupProtocol(identifiers[i], identifierLocs[i]);
1521    protocols.push_back(proto);
1522    if (proto)
1523      ++numProtocolsResolved;
1524  }
1525
1526  // If all of the names were protocols, these were protocol qualifiers.
1527  if (numProtocolsResolved == identifiers.size())
1528    return resolvedAsProtocols();
1529
1530  // Attempt to resolve all of the identifiers as type names or
1531  // Objective-C class names. The latter is technically ill-formed,
1532  // but is probably something like \c NSArray<NSView *> missing the
1533  // \c*.
1534  typedef llvm::PointerUnion<TypeDecl *, ObjCInterfaceDecl *> TypeOrClassDecl;
1535  SmallVector<TypeOrClassDecl, 4> typeDecls;
1536  unsigned numTypeDeclsResolved = 0;
1537  for (unsigned i = 0, n = identifiers.size(); i != n; ++i) {
1538    NamedDecl *decl = LookupSingleName(S, identifiers[i], identifierLocs[i],
1539                                       LookupOrdinaryName);
1540    if (!decl) {
1541      typeDecls.push_back(TypeOrClassDecl());
1542      continue;
1543    }
1544
1545    if (auto typeDecl = dyn_cast<TypeDecl>(decl)) {
1546      typeDecls.push_back(typeDecl);
1547      ++numTypeDeclsResolved;
1548      continue;
1549    }
1550
1551    if (auto objcClass = dyn_cast<ObjCInterfaceDecl>(decl)) {
1552      typeDecls.push_back(objcClass);
1553      ++numTypeDeclsResolved;
1554      continue;
1555    }
1556
1557    typeDecls.push_back(TypeOrClassDecl());
1558  }
1559
1560  AttributeFactory attrFactory;
1561
1562  // Local function that forms a reference to the given type or
1563  // Objective-C class declaration.
1564  auto resolveTypeReference = [&](TypeOrClassDecl typeDecl, SourceLocation loc)
1565                                -> TypeResult {
1566    // Form declaration specifiers. They simply refer to the type.
1567    DeclSpec DS(attrFactory);
1568    const char* prevSpec; // unused
1569    unsigned diagID; // unused
1570    QualType type;
1571    if (auto *actualTypeDecl = typeDecl.dyn_cast<TypeDecl *>())
1572      type = Context.getTypeDeclType(actualTypeDecl);
1573    else
1574      type = Context.getObjCInterfaceType(typeDecl.get<ObjCInterfaceDecl *>());
1575    TypeSourceInfo *parsedTSInfo = Context.getTrivialTypeSourceInfo(type, loc);
1576    ParsedType parsedType = CreateParsedType(type, parsedTSInfo);
1577    DS.SetTypeSpecType(DeclSpec::TST_typename, loc, prevSpec, diagID,
1578                       parsedType, Context.getPrintingPolicy());
1579    // Use the identifier location for the type source range.
1580    DS.SetRangeStart(loc);
1581    DS.SetRangeEnd(loc);
1582
1583    // Form the declarator.
1584    Declarator D(DS, DeclaratorContext::TypeNameContext);
1585
1586    // If we have a typedef of an Objective-C class type that is missing a '*',
1587    // add the '*'.
1588    if (type->getAs<ObjCInterfaceType>()) {
1589      SourceLocation starLoc = getLocForEndOfToken(loc);
1590      D.AddTypeInfo(DeclaratorChunk::getPointer(/*TypeQuals=*/0, starLoc,
1591                                                SourceLocation(),
1592                                                SourceLocation(),
1593                                                SourceLocation(),
1594                                                SourceLocation(),
1595                                                SourceLocation()),
1596                                                starLoc);
1597
1598      // Diagnose the missing '*'.
1599      Diag(loc, diag::err_objc_type_arg_missing_star)
1600        << type
1601        << FixItHint::CreateInsertion(starLoc, " *");
1602    }
1603
1604    // Convert this to a type.
1605    return ActOnTypeName(S, D);
1606  };
1607
1608  // Local function that updates the declaration specifiers with
1609  // type argument information.
1610  auto resolvedAsTypeDecls = [&] {
1611    // We did not resolve these as protocols.
1612    protocols.clear();
1613
1614    assert(numTypeDeclsResolved == identifiers.size() && "Unresolved type decl");
1615    // Map type declarations to type arguments.
1616    for (unsigned i = 0, n = identifiers.size(); i != n; ++i) {
1617      // Map type reference to a type.
1618      TypeResult type = resolveTypeReference(typeDecls[i], identifierLocs[i]);
1619      if (!type.isUsable()) {
1620        typeArgs.clear();
1621        return;
1622      }
1623
1624      typeArgs.push_back(type.get());
1625    }
1626
1627    typeArgsLAngleLoc = lAngleLoc;
1628    typeArgsRAngleLoc = rAngleLoc;
1629  };
1630
1631  // If all of the identifiers can be resolved as type names or
1632  // Objective-C class names, we have type arguments.
1633  if (numTypeDeclsResolved == identifiers.size())
1634    return resolvedAsTypeDecls();
1635
1636  // Error recovery: some names weren't found, or we have a mix of
1637  // type and protocol names. Go resolve all of the unresolved names
1638  // and complain if we can't find a consistent answer.
1639  LookupNameKind lookupKind = LookupAnyName;
1640  for (unsigned i = 0, n = identifiers.size(); i != n; ++i) {
1641    // If we already have a protocol or type. Check whether it is the
1642    // right thing.
1643    if (protocols[i] || typeDecls[i]) {
1644      // If we haven't figured out whether we want types or protocols
1645      // yet, try to figure it out from this name.
1646      if (lookupKind == LookupAnyName) {
1647        // If this name refers to both a protocol and a type (e.g., \c
1648        // NSObject), don't conclude anything yet.
1649        if (protocols[i] && typeDecls[i])
1650          continue;
1651
1652        // Otherwise, let this name decide whether we'll be correcting
1653        // toward types or protocols.
1654        lookupKind = protocols[i] ? LookupObjCProtocolName
1655                                  : LookupOrdinaryName;
1656        continue;
1657      }
1658
1659      // If we want protocols and we have a protocol, there's nothing
1660      // more to do.
1661      if (lookupKind == LookupObjCProtocolName && protocols[i])
1662        continue;
1663
1664      // If we want types and we have a type declaration, there's
1665      // nothing more to do.
1666      if (lookupKind == LookupOrdinaryName && typeDecls[i])
1667        continue;
1668
1669      // We have a conflict: some names refer to protocols and others
1670      // refer to types.
1671      DiagnoseTypeArgsAndProtocols(identifiers[0], identifierLocs[0],
1672                                   identifiers[i], identifierLocs[i],
1673                                   protocols[i] != nullptr);
1674
1675      protocols.clear();
1676      typeArgs.clear();
1677      return;
1678    }
1679
1680    // Perform typo correction on the name.
1681    ObjCTypeArgOrProtocolValidatorCCC CCC(Context, lookupKind);
1682    TypoCorrection corrected =
1683        CorrectTypo(DeclarationNameInfo(identifiers[i], identifierLocs[i]),
1684                    lookupKind, S, nullptr, CCC, CTK_ErrorRecovery);
1685    if (corrected) {
1686      // Did we find a protocol?
1687      if (auto proto = corrected.getCorrectionDeclAs<ObjCProtocolDecl>()) {
1688        diagnoseTypo(corrected,
1689                     PDiag(diag::err_undeclared_protocol_suggest)
1690                       << identifiers[i]);
1691        lookupKind = LookupObjCProtocolName;
1692        protocols[i] = proto;
1693        ++numProtocolsResolved;
1694        continue;
1695      }
1696
1697      // Did we find a type?
1698      if (auto typeDecl = corrected.getCorrectionDeclAs<TypeDecl>()) {
1699        diagnoseTypo(corrected,
1700                     PDiag(diag::err_unknown_typename_suggest)
1701                       << identifiers[i]);
1702        lookupKind = LookupOrdinaryName;
1703        typeDecls[i] = typeDecl;
1704        ++numTypeDeclsResolved;
1705        continue;
1706      }
1707
1708      // Did we find an Objective-C class?
1709      if (auto objcClass = corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
1710        diagnoseTypo(corrected,
1711                     PDiag(diag::err_unknown_type_or_class_name_suggest)
1712                       << identifiers[i] << true);
1713        lookupKind = LookupOrdinaryName;
1714        typeDecls[i] = objcClass;
1715        ++numTypeDeclsResolved;
1716        continue;
1717      }
1718    }
1719
1720    // We couldn't find anything.
1721    Diag(identifierLocs[i],
1722         (lookupKind == LookupAnyName ? diag::err_objc_type_arg_missing
1723          : lookupKind == LookupObjCProtocolName ? diag::err_undeclared_protocol
1724          : diag::err_unknown_typename))
1725      << identifiers[i];
1726    protocols.clear();
1727    typeArgs.clear();
1728    return;
1729  }
1730
1731  // If all of the names were (corrected to) protocols, these were
1732  // protocol qualifiers.
1733  if (numProtocolsResolved == identifiers.size())
1734    return resolvedAsProtocols();
1735
1736  // Otherwise, all of the names were (corrected to) types.
1737  assert(numTypeDeclsResolved == identifiers.size() && "Not all types?");
1738  return resolvedAsTypeDecls();
1739}
1740
1741/// DiagnoseClassExtensionDupMethods - Check for duplicate declaration of
1742/// a class method in its extension.
1743///
1744void Sema::DiagnoseClassExtensionDupMethods(ObjCCategoryDecl *CAT,
1745                                            ObjCInterfaceDecl *ID) {
1746  if (!ID)
1747    return;  // Possibly due to previous error
1748
1749  llvm::DenseMap<Selector, const ObjCMethodDecl*> MethodMap;
1750  for (auto *MD : ID->methods())
1751    MethodMap[MD->getSelector()] = MD;
1752
1753  if (MethodMap.empty())
1754    return;
1755  for (const auto *Method : CAT->methods()) {
1756    const ObjCMethodDecl *&PrevMethod = MethodMap[Method->getSelector()];
1757    if (PrevMethod &&
1758        (PrevMethod->isInstanceMethod() == Method->isInstanceMethod()) &&
1759        !MatchTwoMethodDeclarations(Method, PrevMethod)) {
1760      Diag(Method->getLocation(), diag::err_duplicate_method_decl)
1761            << Method->getDeclName();
1762      Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
1763    }
1764  }
1765}
1766
1767/// ActOnForwardProtocolDeclaration - Handle \@protocol foo;
1768Sema::DeclGroupPtrTy
1769Sema::ActOnForwardProtocolDeclaration(SourceLocation AtProtocolLoc,
1770                                      ArrayRef<IdentifierLocPair> IdentList,
1771                                      const ParsedAttributesView &attrList) {
1772  SmallVector<Decl *, 8> DeclsInGroup;
1773  for (const IdentifierLocPair &IdentPair : IdentList) {
1774    IdentifierInfo *Ident = IdentPair.first;
1775    ObjCProtocolDecl *PrevDecl = LookupProtocol(Ident, IdentPair.second,
1776                                                forRedeclarationInCurContext());
1777    ObjCProtocolDecl *PDecl
1778      = ObjCProtocolDecl::Create(Context, CurContext, Ident,
1779                                 IdentPair.second, AtProtocolLoc,
1780                                 PrevDecl);
1781
1782    PushOnScopeChains(PDecl, TUScope);
1783    CheckObjCDeclScope(PDecl);
1784
1785    ProcessDeclAttributeList(TUScope, PDecl, attrList);
1786    AddPragmaAttributes(TUScope, PDecl);
1787
1788    if (PrevDecl)
1789      mergeDeclAttributes(PDecl, PrevDecl);
1790
1791    DeclsInGroup.push_back(PDecl);
1792  }
1793
1794  return BuildDeclaratorGroup(DeclsInGroup);
1795}
1796
1797Decl *Sema::ActOnStartCategoryInterface(
1798    SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
1799    SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
1800    IdentifierInfo *CategoryName, SourceLocation CategoryLoc,
1801    Decl *const *ProtoRefs, unsigned NumProtoRefs,
1802    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
1803    const ParsedAttributesView &AttrList) {
1804  ObjCCategoryDecl *CDecl;
1805  ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName, ClassLoc, true);
1806
1807  /// Check that class of this category is already completely declared.
1808
1809  if (!IDecl
1810      || RequireCompleteType(ClassLoc, Context.getObjCInterfaceType(IDecl),
1811                             diag::err_category_forward_interface,
1812                             CategoryName == nullptr)) {
1813    // Create an invalid ObjCCategoryDecl to serve as context for
1814    // the enclosing method declarations.  We mark the decl invalid
1815    // to make it clear that this isn't a valid AST.
1816    CDecl = ObjCCategoryDecl::Create(Context, CurContext, AtInterfaceLoc,
1817                                     ClassLoc, CategoryLoc, CategoryName,
1818                                     IDecl, typeParamList);
1819    CDecl->setInvalidDecl();
1820    CurContext->addDecl(CDecl);
1821
1822    if (!IDecl)
1823      Diag(ClassLoc, diag::err_undef_interface) << ClassName;
1824    return ActOnObjCContainerStartDefinition(CDecl);
1825  }
1826
1827  if (!CategoryName && IDecl->getImplementation()) {
1828    Diag(ClassLoc, diag::err_class_extension_after_impl) << ClassName;
1829    Diag(IDecl->getImplementation()->getLocation(),
1830          diag::note_implementation_declared);
1831  }
1832
1833  if (CategoryName) {
1834    /// Check for duplicate interface declaration for this category
1835    if (ObjCCategoryDecl *Previous
1836          = IDecl->FindCategoryDeclaration(CategoryName)) {
1837      // Class extensions can be declared multiple times, categories cannot.
1838      Diag(CategoryLoc, diag::warn_dup_category_def)
1839        << ClassName << CategoryName;
1840      Diag(Previous->getLocation(), diag::note_previous_definition);
1841    }
1842  }
1843
1844  // If we have a type parameter list, check it.
1845  if (typeParamList) {
1846    if (auto prevTypeParamList = IDecl->getTypeParamList()) {
1847      if (checkTypeParamListConsistency(*this, prevTypeParamList, typeParamList,
1848                                        CategoryName
1849                                          ? TypeParamListContext::Category
1850                                          : TypeParamListContext::Extension))
1851        typeParamList = nullptr;
1852    } else {
1853      Diag(typeParamList->getLAngleLoc(),
1854           diag::err_objc_parameterized_category_nonclass)
1855        << (CategoryName != nullptr)
1856        << ClassName
1857        << typeParamList->getSourceRange();
1858
1859      typeParamList = nullptr;
1860    }
1861  }
1862
1863  CDecl = ObjCCategoryDecl::Create(Context, CurContext, AtInterfaceLoc,
1864                                   ClassLoc, CategoryLoc, CategoryName, IDecl,
1865                                   typeParamList);
1866  // FIXME: PushOnScopeChains?
1867  CurContext->addDecl(CDecl);
1868
1869  // Process the attributes before looking at protocols to ensure that the
1870  // availability attribute is attached to the category to provide availability
1871  // checking for protocol uses.
1872  ProcessDeclAttributeList(TUScope, CDecl, AttrList);
1873  AddPragmaAttributes(TUScope, CDecl);
1874
1875  if (NumProtoRefs) {
1876    diagnoseUseOfProtocols(*this, CDecl, (ObjCProtocolDecl*const*)ProtoRefs,
1877                           NumProtoRefs, ProtoLocs);
1878    CDecl->setProtocolList((ObjCProtocolDecl*const*)ProtoRefs, NumProtoRefs,
1879                           ProtoLocs, Context);
1880    // Protocols in the class extension belong to the class.
1881    if (CDecl->IsClassExtension())
1882     IDecl->mergeClassExtensionProtocolList((ObjCProtocolDecl*const*)ProtoRefs,
1883                                            NumProtoRefs, Context);
1884  }
1885
1886  CheckObjCDeclScope(CDecl);
1887  return ActOnObjCContainerStartDefinition(CDecl);
1888}
1889
1890/// ActOnStartCategoryImplementation - Perform semantic checks on the
1891/// category implementation declaration and build an ObjCCategoryImplDecl
1892/// object.
1893Decl *Sema::ActOnStartCategoryImplementation(
1894                      SourceLocation AtCatImplLoc,
1895                      IdentifierInfo *ClassName, SourceLocation ClassLoc,
1896                      IdentifierInfo *CatName, SourceLocation CatLoc,
1897                      const ParsedAttributesView &Attrs) {
1898  ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName, ClassLoc, true);
1899  ObjCCategoryDecl *CatIDecl = nullptr;
1900  if (IDecl && IDecl->hasDefinition()) {
1901    CatIDecl = IDecl->FindCategoryDeclaration(CatName);
1902    if (!CatIDecl) {
1903      // Category @implementation with no corresponding @interface.
1904      // Create and install one.
1905      CatIDecl = ObjCCategoryDecl::Create(Context, CurContext, AtCatImplLoc,
1906                                          ClassLoc, CatLoc,
1907                                          CatName, IDecl,
1908                                          /*typeParamList=*/nullptr);
1909      CatIDecl->setImplicit();
1910    }
1911  }
1912
1913  ObjCCategoryImplDecl *CDecl =
1914    ObjCCategoryImplDecl::Create(Context, CurContext, CatName, IDecl,
1915                                 ClassLoc, AtCatImplLoc, CatLoc);
1916  /// Check that class of this category is already completely declared.
1917  if (!IDecl) {
1918    Diag(ClassLoc, diag::err_undef_interface) << ClassName;
1919    CDecl->setInvalidDecl();
1920  } else if (RequireCompleteType(ClassLoc, Context.getObjCInterfaceType(IDecl),
1921                                 diag::err_undef_interface)) {
1922    CDecl->setInvalidDecl();
1923  }
1924
1925  ProcessDeclAttributeList(TUScope, CDecl, Attrs);
1926  AddPragmaAttributes(TUScope, CDecl);
1927
1928  // FIXME: PushOnScopeChains?
1929  CurContext->addDecl(CDecl);
1930
1931  // If the interface has the objc_runtime_visible attribute, we
1932  // cannot implement a category for it.
1933  if (IDecl && IDecl->hasAttr<ObjCRuntimeVisibleAttr>()) {
1934    Diag(ClassLoc, diag::err_objc_runtime_visible_category)
1935      << IDecl->getDeclName();
1936  }
1937
1938  /// Check that CatName, category name, is not used in another implementation.
1939  if (CatIDecl) {
1940    if (CatIDecl->getImplementation()) {
1941      Diag(ClassLoc, diag::err_dup_implementation_category) << ClassName
1942        << CatName;
1943      Diag(CatIDecl->getImplementation()->getLocation(),
1944           diag::note_previous_definition);
1945      CDecl->setInvalidDecl();
1946    } else {
1947      CatIDecl->setImplementation(CDecl);
1948      // Warn on implementating category of deprecated class under
1949      // -Wdeprecated-implementations flag.
1950      DiagnoseObjCImplementedDeprecations(*this, CatIDecl,
1951                                          CDecl->getLocation());
1952    }
1953  }
1954
1955  CheckObjCDeclScope(CDecl);
1956  return ActOnObjCContainerStartDefinition(CDecl);
1957}
1958
1959Decl *Sema::ActOnStartClassImplementation(
1960                      SourceLocation AtClassImplLoc,
1961                      IdentifierInfo *ClassName, SourceLocation ClassLoc,
1962                      IdentifierInfo *SuperClassname,
1963                      SourceLocation SuperClassLoc,
1964                      const ParsedAttributesView &Attrs) {
1965  ObjCInterfaceDecl *IDecl = nullptr;
1966  // Check for another declaration kind with the same name.
1967  NamedDecl *PrevDecl
1968    = LookupSingleName(TUScope, ClassName, ClassLoc, LookupOrdinaryName,
1969                       forRedeclarationInCurContext());
1970  if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
1971    Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
1972    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1973  } else if ((IDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl))) {
1974    // FIXME: This will produce an error if the definition of the interface has
1975    // been imported from a module but is not visible.
1976    RequireCompleteType(ClassLoc, Context.getObjCInterfaceType(IDecl),
1977                        diag::warn_undef_interface);
1978  } else {
1979    // We did not find anything with the name ClassName; try to correct for
1980    // typos in the class name.
1981    ObjCInterfaceValidatorCCC CCC{};
1982    TypoCorrection Corrected =
1983        CorrectTypo(DeclarationNameInfo(ClassName, ClassLoc),
1984                    LookupOrdinaryName, TUScope, nullptr, CCC, CTK_NonError);
1985    if (Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
1986      // Suggest the (potentially) correct interface name. Don't provide a
1987      // code-modification hint or use the typo name for recovery, because
1988      // this is just a warning. The program may actually be correct.
1989      diagnoseTypo(Corrected,
1990                   PDiag(diag::warn_undef_interface_suggest) << ClassName,
1991                   /*ErrorRecovery*/false);
1992    } else {
1993      Diag(ClassLoc, diag::warn_undef_interface) << ClassName;
1994    }
1995  }
1996
1997  // Check that super class name is valid class name
1998  ObjCInterfaceDecl *SDecl = nullptr;
1999  if (SuperClassname) {
2000    // Check if a different kind of symbol declared in this scope.
2001    PrevDecl = LookupSingleName(TUScope, SuperClassname, SuperClassLoc,
2002                                LookupOrdinaryName);
2003    if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
2004      Diag(SuperClassLoc, diag::err_redefinition_different_kind)
2005        << SuperClassname;
2006      Diag(PrevDecl->getLocation(), diag::note_previous_definition);
2007    } else {
2008      SDecl = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
2009      if (SDecl && !SDecl->hasDefinition())
2010        SDecl = nullptr;
2011      if (!SDecl)
2012        Diag(SuperClassLoc, diag::err_undef_superclass)
2013          << SuperClassname << ClassName;
2014      else if (IDecl && !declaresSameEntity(IDecl->getSuperClass(), SDecl)) {
2015        // This implementation and its interface do not have the same
2016        // super class.
2017        Diag(SuperClassLoc, diag::err_conflicting_super_class)
2018          << SDecl->getDeclName();
2019        Diag(SDecl->getLocation(), diag::note_previous_definition);
2020      }
2021    }
2022  }
2023
2024  if (!IDecl) {
2025    // Legacy case of @implementation with no corresponding @interface.
2026    // Build, chain & install the interface decl into the identifier.
2027
2028    // FIXME: Do we support attributes on the @implementation? If so we should
2029    // copy them over.
2030    IDecl = ObjCInterfaceDecl::Create(Context, CurContext, AtClassImplLoc,
2031                                      ClassName, /*typeParamList=*/nullptr,
2032                                      /*PrevDecl=*/nullptr, ClassLoc,
2033                                      true);
2034    AddPragmaAttributes(TUScope, IDecl);
2035    IDecl->startDefinition();
2036    if (SDecl) {
2037      IDecl->setSuperClass(Context.getTrivialTypeSourceInfo(
2038                             Context.getObjCInterfaceType(SDecl),
2039                             SuperClassLoc));
2040      IDecl->setEndOfDefinitionLoc(SuperClassLoc);
2041    } else {
2042      IDecl->setEndOfDefinitionLoc(ClassLoc);
2043    }
2044
2045    PushOnScopeChains(IDecl, TUScope);
2046  } else {
2047    // Mark the interface as being completed, even if it was just as
2048    //   @class ....;
2049    // declaration; the user cannot reopen it.
2050    if (!IDecl->hasDefinition())
2051      IDecl->startDefinition();
2052  }
2053
2054  ObjCImplementationDecl* IMPDecl =
2055    ObjCImplementationDecl::Create(Context, CurContext, IDecl, SDecl,
2056                                   ClassLoc, AtClassImplLoc, SuperClassLoc);
2057
2058  ProcessDeclAttributeList(TUScope, IMPDecl, Attrs);
2059  AddPragmaAttributes(TUScope, IMPDecl);
2060
2061  if (CheckObjCDeclScope(IMPDecl))
2062    return ActOnObjCContainerStartDefinition(IMPDecl);
2063
2064  // Check that there is no duplicate implementation of this class.
2065  if (IDecl->getImplementation()) {
2066    // FIXME: Don't leak everything!
2067    Diag(ClassLoc, diag::err_dup_implementation_class) << ClassName;
2068    Diag(IDecl->getImplementation()->getLocation(),
2069         diag::note_previous_definition);
2070    IMPDecl->setInvalidDecl();
2071  } else { // add it to the list.
2072    IDecl->setImplementation(IMPDecl);
2073    PushOnScopeChains(IMPDecl, TUScope);
2074    // Warn on implementating deprecated class under
2075    // -Wdeprecated-implementations flag.
2076    DiagnoseObjCImplementedDeprecations(*this, IDecl, IMPDecl->getLocation());
2077  }
2078
2079  // If the superclass has the objc_runtime_visible attribute, we
2080  // cannot implement a subclass of it.
2081  if (IDecl->getSuperClass() &&
2082      IDecl->getSuperClass()->hasAttr<ObjCRuntimeVisibleAttr>()) {
2083    Diag(ClassLoc, diag::err_objc_runtime_visible_subclass)
2084      << IDecl->getDeclName()
2085      << IDecl->getSuperClass()->getDeclName();
2086  }
2087
2088  return ActOnObjCContainerStartDefinition(IMPDecl);
2089}
2090
2091Sema::DeclGroupPtrTy
2092Sema::ActOnFinishObjCImplementation(Decl *ObjCImpDecl, ArrayRef<Decl *> Decls) {
2093  SmallVector<Decl *, 64> DeclsInGroup;
2094  DeclsInGroup.reserve(Decls.size() + 1);
2095
2096  for (unsigned i = 0, e = Decls.size(); i != e; ++i) {
2097    Decl *Dcl = Decls[i];
2098    if (!Dcl)
2099      continue;
2100    if (Dcl->getDeclContext()->isFileContext())
2101      Dcl->setTopLevelDeclInObjCContainer();
2102    DeclsInGroup.push_back(Dcl);
2103  }
2104
2105  DeclsInGroup.push_back(ObjCImpDecl);
2106
2107  return BuildDeclaratorGroup(DeclsInGroup);
2108}
2109
2110void Sema::CheckImplementationIvars(ObjCImplementationDecl *ImpDecl,
2111                                    ObjCIvarDecl **ivars, unsigned numIvars,
2112                                    SourceLocation RBrace) {
2113  assert(ImpDecl && "missing implementation decl");
2114  ObjCInterfaceDecl* IDecl = ImpDecl->getClassInterface();
2115  if (!IDecl)
2116    return;
2117  /// Check case of non-existing \@interface decl.
2118  /// (legacy objective-c \@implementation decl without an \@interface decl).
2119  /// Add implementations's ivar to the synthesize class's ivar list.
2120  if (IDecl->isImplicitInterfaceDecl()) {
2121    IDecl->setEndOfDefinitionLoc(RBrace);
2122    // Add ivar's to class's DeclContext.
2123    for (unsigned i = 0, e = numIvars; i != e; ++i) {
2124      ivars[i]->setLexicalDeclContext(ImpDecl);
2125      IDecl->makeDeclVisibleInContext(ivars[i]);
2126      ImpDecl->addDecl(ivars[i]);
2127    }
2128
2129    return;
2130  }
2131  // If implementation has empty ivar list, just return.
2132  if (numIvars == 0)
2133    return;
2134
2135  assert(ivars && "missing @implementation ivars");
2136  if (LangOpts.ObjCRuntime.isNonFragile()) {
2137    if (ImpDecl->getSuperClass())
2138      Diag(ImpDecl->getLocation(), diag::warn_on_superclass_use);
2139    for (unsigned i = 0; i < numIvars; i++) {
2140      ObjCIvarDecl* ImplIvar = ivars[i];
2141      if (const ObjCIvarDecl *ClsIvar =
2142            IDecl->getIvarDecl(ImplIvar->getIdentifier())) {
2143        Diag(ImplIvar->getLocation(), diag::err_duplicate_ivar_declaration);
2144        Diag(ClsIvar->getLocation(), diag::note_previous_definition);
2145        continue;
2146      }
2147      // Check class extensions (unnamed categories) for duplicate ivars.
2148      for (const auto *CDecl : IDecl->visible_extensions()) {
2149        if (const ObjCIvarDecl *ClsExtIvar =
2150            CDecl->getIvarDecl(ImplIvar->getIdentifier())) {
2151          Diag(ImplIvar->getLocation(), diag::err_duplicate_ivar_declaration);
2152          Diag(ClsExtIvar->getLocation(), diag::note_previous_definition);
2153          continue;
2154        }
2155      }
2156      // Instance ivar to Implementation's DeclContext.
2157      ImplIvar->setLexicalDeclContext(ImpDecl);
2158      IDecl->makeDeclVisibleInContext(ImplIvar);
2159      ImpDecl->addDecl(ImplIvar);
2160    }
2161    return;
2162  }
2163  // Check interface's Ivar list against those in the implementation.
2164  // names and types must match.
2165  //
2166  unsigned j = 0;
2167  ObjCInterfaceDecl::ivar_iterator
2168    IVI = IDecl->ivar_begin(), IVE = IDecl->ivar_end();
2169  for (; numIvars > 0 && IVI != IVE; ++IVI) {
2170    ObjCIvarDecl* ImplIvar = ivars[j++];
2171    ObjCIvarDecl* ClsIvar = *IVI;
2172    assert (ImplIvar && "missing implementation ivar");
2173    assert (ClsIvar && "missing class ivar");
2174
2175    // First, make sure the types match.
2176    if (!Context.hasSameType(ImplIvar->getType(), ClsIvar->getType())) {
2177      Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_type)
2178        << ImplIvar->getIdentifier()
2179        << ImplIvar->getType() << ClsIvar->getType();
2180      Diag(ClsIvar->getLocation(), diag::note_previous_definition);
2181    } else if (ImplIvar->isBitField() && ClsIvar->isBitField() &&
2182               ImplIvar->getBitWidthValue(Context) !=
2183               ClsIvar->getBitWidthValue(Context)) {
2184      Diag(ImplIvar->getBitWidth()->getBeginLoc(),
2185           diag::err_conflicting_ivar_bitwidth)
2186          << ImplIvar->getIdentifier();
2187      Diag(ClsIvar->getBitWidth()->getBeginLoc(),
2188           diag::note_previous_definition);
2189    }
2190    // Make sure the names are identical.
2191    if (ImplIvar->getIdentifier() != ClsIvar->getIdentifier()) {
2192      Diag(ImplIvar->getLocation(), diag::err_conflicting_ivar_name)
2193        << ImplIvar->getIdentifier() << ClsIvar->getIdentifier();
2194      Diag(ClsIvar->getLocation(), diag::note_previous_definition);
2195    }
2196    --numIvars;
2197  }
2198
2199  if (numIvars > 0)
2200    Diag(ivars[j]->getLocation(), diag::err_inconsistent_ivar_count);
2201  else if (IVI != IVE)
2202    Diag(IVI->getLocation(), diag::err_inconsistent_ivar_count);
2203}
2204
2205static void WarnUndefinedMethod(Sema &S, SourceLocation ImpLoc,
2206                                ObjCMethodDecl *method,
2207                                bool &IncompleteImpl,
2208                                unsigned DiagID,
2209                                NamedDecl *NeededFor = nullptr) {
2210  // No point warning no definition of method which is 'unavailable'.
2211  if (method->getAvailability() == AR_Unavailable)
2212    return;
2213
2214  // FIXME: For now ignore 'IncompleteImpl'.
2215  // Previously we grouped all unimplemented methods under a single
2216  // warning, but some users strongly voiced that they would prefer
2217  // separate warnings.  We will give that approach a try, as that
2218  // matches what we do with protocols.
2219  {
2220    const Sema::SemaDiagnosticBuilder &B = S.Diag(ImpLoc, DiagID);
2221    B << method;
2222    if (NeededFor)
2223      B << NeededFor;
2224  }
2225
2226  // Issue a note to the original declaration.
2227  SourceLocation MethodLoc = method->getBeginLoc();
2228  if (MethodLoc.isValid())
2229    S.Diag(MethodLoc, diag::note_method_declared_at) << method;
2230}
2231
2232/// Determines if type B can be substituted for type A.  Returns true if we can
2233/// guarantee that anything that the user will do to an object of type A can
2234/// also be done to an object of type B.  This is trivially true if the two
2235/// types are the same, or if B is a subclass of A.  It becomes more complex
2236/// in cases where protocols are involved.
2237///
2238/// Object types in Objective-C describe the minimum requirements for an
2239/// object, rather than providing a complete description of a type.  For
2240/// example, if A is a subclass of B, then B* may refer to an instance of A.
2241/// The principle of substitutability means that we may use an instance of A
2242/// anywhere that we may use an instance of B - it will implement all of the
2243/// ivars of B and all of the methods of B.
2244///
2245/// This substitutability is important when type checking methods, because
2246/// the implementation may have stricter type definitions than the interface.
2247/// The interface specifies minimum requirements, but the implementation may
2248/// have more accurate ones.  For example, a method may privately accept
2249/// instances of B, but only publish that it accepts instances of A.  Any
2250/// object passed to it will be type checked against B, and so will implicitly
2251/// by a valid A*.  Similarly, a method may return a subclass of the class that
2252/// it is declared as returning.
2253///
2254/// This is most important when considering subclassing.  A method in a
2255/// subclass must accept any object as an argument that its superclass's
2256/// implementation accepts.  It may, however, accept a more general type
2257/// without breaking substitutability (i.e. you can still use the subclass
2258/// anywhere that you can use the superclass, but not vice versa).  The
2259/// converse requirement applies to return types: the return type for a
2260/// subclass method must be a valid object of the kind that the superclass
2261/// advertises, but it may be specified more accurately.  This avoids the need
2262/// for explicit down-casting by callers.
2263///
2264/// Note: This is a stricter requirement than for assignment.
2265static bool isObjCTypeSubstitutable(ASTContext &Context,
2266                                    const ObjCObjectPointerType *A,
2267                                    const ObjCObjectPointerType *B,
2268                                    bool rejectId) {
2269  // Reject a protocol-unqualified id.
2270  if (rejectId && B->isObjCIdType()) return false;
2271
2272  // If B is a qualified id, then A must also be a qualified id and it must
2273  // implement all of the protocols in B.  It may not be a qualified class.
2274  // For example, MyClass<A> can be assigned to id<A>, but MyClass<A> is a
2275  // stricter definition so it is not substitutable for id<A>.
2276  if (B->isObjCQualifiedIdType()) {
2277    return A->isObjCQualifiedIdType() &&
2278           Context.ObjCQualifiedIdTypesAreCompatible(A, B, false);
2279  }
2280
2281  /*
2282  // id is a special type that bypasses type checking completely.  We want a
2283  // warning when it is used in one place but not another.
2284  if (C.isObjCIdType(A) || C.isObjCIdType(B)) return false;
2285
2286
2287  // If B is a qualified id, then A must also be a qualified id (which it isn't
2288  // if we've got this far)
2289  if (B->isObjCQualifiedIdType()) return false;
2290  */
2291
2292  // Now we know that A and B are (potentially-qualified) class types.  The
2293  // normal rules for assignment apply.
2294  return Context.canAssignObjCInterfaces(A, B);
2295}
2296
2297static SourceRange getTypeRange(TypeSourceInfo *TSI) {
2298  return (TSI ? TSI->getTypeLoc().getSourceRange() : SourceRange());
2299}
2300
2301/// Determine whether two set of Objective-C declaration qualifiers conflict.
2302static bool objcModifiersConflict(Decl::ObjCDeclQualifier x,
2303                                  Decl::ObjCDeclQualifier y) {
2304  return (x & ~Decl::OBJC_TQ_CSNullability) !=
2305         (y & ~Decl::OBJC_TQ_CSNullability);
2306}
2307
2308static bool CheckMethodOverrideReturn(Sema &S,
2309                                      ObjCMethodDecl *MethodImpl,
2310                                      ObjCMethodDecl *MethodDecl,
2311                                      bool IsProtocolMethodDecl,
2312                                      bool IsOverridingMode,
2313                                      bool Warn) {
2314  if (IsProtocolMethodDecl &&
2315      objcModifiersConflict(MethodDecl->getObjCDeclQualifier(),
2316                            MethodImpl->getObjCDeclQualifier())) {
2317    if (Warn) {
2318      S.Diag(MethodImpl->getLocation(),
2319             (IsOverridingMode
2320                  ? diag::warn_conflicting_overriding_ret_type_modifiers
2321                  : diag::warn_conflicting_ret_type_modifiers))
2322          << MethodImpl->getDeclName()
2323          << MethodImpl->getReturnTypeSourceRange();
2324      S.Diag(MethodDecl->getLocation(), diag::note_previous_declaration)
2325          << MethodDecl->getReturnTypeSourceRange();
2326    }
2327    else
2328      return false;
2329  }
2330  if (Warn && IsOverridingMode &&
2331      !isa<ObjCImplementationDecl>(MethodImpl->getDeclContext()) &&
2332      !S.Context.hasSameNullabilityTypeQualifier(MethodImpl->getReturnType(),
2333                                                 MethodDecl->getReturnType(),
2334                                                 false)) {
2335    auto nullabilityMethodImpl =
2336      *MethodImpl->getReturnType()->getNullability(S.Context);
2337    auto nullabilityMethodDecl =
2338      *MethodDecl->getReturnType()->getNullability(S.Context);
2339      S.Diag(MethodImpl->getLocation(),
2340             diag::warn_conflicting_nullability_attr_overriding_ret_types)
2341        << DiagNullabilityKind(
2342             nullabilityMethodImpl,
2343             ((MethodImpl->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
2344              != 0))
2345        << DiagNullabilityKind(
2346             nullabilityMethodDecl,
2347             ((MethodDecl->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
2348                != 0));
2349      S.Diag(MethodDecl->getLocation(), diag::note_previous_declaration);
2350  }
2351
2352  if (S.Context.hasSameUnqualifiedType(MethodImpl->getReturnType(),
2353                                       MethodDecl->getReturnType()))
2354    return true;
2355  if (!Warn)
2356    return false;
2357
2358  unsigned DiagID =
2359    IsOverridingMode ? diag::warn_conflicting_overriding_ret_types
2360                     : diag::warn_conflicting_ret_types;
2361
2362  // Mismatches between ObjC pointers go into a different warning
2363  // category, and sometimes they're even completely whitelisted.
2364  if (const ObjCObjectPointerType *ImplPtrTy =
2365          MethodImpl->getReturnType()->getAs<ObjCObjectPointerType>()) {
2366    if (const ObjCObjectPointerType *IfacePtrTy =
2367            MethodDecl->getReturnType()->getAs<ObjCObjectPointerType>()) {
2368      // Allow non-matching return types as long as they don't violate
2369      // the principle of substitutability.  Specifically, we permit
2370      // return types that are subclasses of the declared return type,
2371      // or that are more-qualified versions of the declared type.
2372      if (isObjCTypeSubstitutable(S.Context, IfacePtrTy, ImplPtrTy, false))
2373        return false;
2374
2375      DiagID =
2376        IsOverridingMode ? diag::warn_non_covariant_overriding_ret_types
2377                         : diag::warn_non_covariant_ret_types;
2378    }
2379  }
2380
2381  S.Diag(MethodImpl->getLocation(), DiagID)
2382      << MethodImpl->getDeclName() << MethodDecl->getReturnType()
2383      << MethodImpl->getReturnType()
2384      << MethodImpl->getReturnTypeSourceRange();
2385  S.Diag(MethodDecl->getLocation(), IsOverridingMode
2386                                        ? diag::note_previous_declaration
2387                                        : diag::note_previous_definition)
2388      << MethodDecl->getReturnTypeSourceRange();
2389  return false;
2390}
2391
2392static bool CheckMethodOverrideParam(Sema &S,
2393                                     ObjCMethodDecl *MethodImpl,
2394                                     ObjCMethodDecl *MethodDecl,
2395                                     ParmVarDecl *ImplVar,
2396                                     ParmVarDecl *IfaceVar,
2397                                     bool IsProtocolMethodDecl,
2398                                     bool IsOverridingMode,
2399                                     bool Warn) {
2400  if (IsProtocolMethodDecl &&
2401      objcModifiersConflict(ImplVar->getObjCDeclQualifier(),
2402                            IfaceVar->getObjCDeclQualifier())) {
2403    if (Warn) {
2404      if (IsOverridingMode)
2405        S.Diag(ImplVar->getLocation(),
2406               diag::warn_conflicting_overriding_param_modifiers)
2407            << getTypeRange(ImplVar->getTypeSourceInfo())
2408            << MethodImpl->getDeclName();
2409      else S.Diag(ImplVar->getLocation(),
2410             diag::warn_conflicting_param_modifiers)
2411          << getTypeRange(ImplVar->getTypeSourceInfo())
2412          << MethodImpl->getDeclName();
2413      S.Diag(IfaceVar->getLocation(), diag::note_previous_declaration)
2414          << getTypeRange(IfaceVar->getTypeSourceInfo());
2415    }
2416    else
2417      return false;
2418  }
2419
2420  QualType ImplTy = ImplVar->getType();
2421  QualType IfaceTy = IfaceVar->getType();
2422  if (Warn && IsOverridingMode &&
2423      !isa<ObjCImplementationDecl>(MethodImpl->getDeclContext()) &&
2424      !S.Context.hasSameNullabilityTypeQualifier(ImplTy, IfaceTy, true)) {
2425    S.Diag(ImplVar->getLocation(),
2426           diag::warn_conflicting_nullability_attr_overriding_param_types)
2427      << DiagNullabilityKind(
2428           *ImplTy->getNullability(S.Context),
2429           ((ImplVar->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
2430            != 0))
2431      << DiagNullabilityKind(
2432           *IfaceTy->getNullability(S.Context),
2433           ((IfaceVar->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
2434            != 0));
2435    S.Diag(IfaceVar->getLocation(), diag::note_previous_declaration);
2436  }
2437  if (S.Context.hasSameUnqualifiedType(ImplTy, IfaceTy))
2438    return true;
2439
2440  if (!Warn)
2441    return false;
2442  unsigned DiagID =
2443    IsOverridingMode ? diag::warn_conflicting_overriding_param_types
2444                     : diag::warn_conflicting_param_types;
2445
2446  // Mismatches between ObjC pointers go into a different warning
2447  // category, and sometimes they're even completely whitelisted.
2448  if (const ObjCObjectPointerType *ImplPtrTy =
2449        ImplTy->getAs<ObjCObjectPointerType>()) {
2450    if (const ObjCObjectPointerType *IfacePtrTy =
2451          IfaceTy->getAs<ObjCObjectPointerType>()) {
2452      // Allow non-matching argument types as long as they don't
2453      // violate the principle of substitutability.  Specifically, the
2454      // implementation must accept any objects that the superclass
2455      // accepts, however it may also accept others.
2456      if (isObjCTypeSubstitutable(S.Context, ImplPtrTy, IfacePtrTy, true))
2457        return false;
2458
2459      DiagID =
2460      IsOverridingMode ? diag::warn_non_contravariant_overriding_param_types
2461                       : diag::warn_non_contravariant_param_types;
2462    }
2463  }
2464
2465  S.Diag(ImplVar->getLocation(), DiagID)
2466    << getTypeRange(ImplVar->getTypeSourceInfo())
2467    << MethodImpl->getDeclName() << IfaceTy << ImplTy;
2468  S.Diag(IfaceVar->getLocation(),
2469         (IsOverridingMode ? diag::note_previous_declaration
2470                           : diag::note_previous_definition))
2471    << getTypeRange(IfaceVar->getTypeSourceInfo());
2472  return false;
2473}
2474
2475/// In ARC, check whether the conventional meanings of the two methods
2476/// match.  If they don't, it's a hard error.
2477static bool checkMethodFamilyMismatch(Sema &S, ObjCMethodDecl *impl,
2478                                      ObjCMethodDecl *decl) {
2479  ObjCMethodFamily implFamily = impl->getMethodFamily();
2480  ObjCMethodFamily declFamily = decl->getMethodFamily();
2481  if (implFamily == declFamily) return false;
2482
2483  // Since conventions are sorted by selector, the only possibility is
2484  // that the types differ enough to cause one selector or the other
2485  // to fall out of the family.
2486  assert(implFamily == OMF_None || declFamily == OMF_None);
2487
2488  // No further diagnostics required on invalid declarations.
2489  if (impl->isInvalidDecl() || decl->isInvalidDecl()) return true;
2490
2491  const ObjCMethodDecl *unmatched = impl;
2492  ObjCMethodFamily family = declFamily;
2493  unsigned errorID = diag::err_arc_lost_method_convention;
2494  unsigned noteID = diag::note_arc_lost_method_convention;
2495  if (declFamily == OMF_None) {
2496    unmatched = decl;
2497    family = implFamily;
2498    errorID = diag::err_arc_gained_method_convention;
2499    noteID = diag::note_arc_gained_method_convention;
2500  }
2501
2502  // Indexes into a %select clause in the diagnostic.
2503  enum FamilySelector {
2504    F_alloc, F_copy, F_mutableCopy = F_copy, F_init, F_new
2505  };
2506  FamilySelector familySelector = FamilySelector();
2507
2508  switch (family) {
2509  case OMF_None: llvm_unreachable("logic error, no method convention");
2510  case OMF_retain:
2511  case OMF_release:
2512  case OMF_autorelease:
2513  case OMF_dealloc:
2514  case OMF_finalize:
2515  case OMF_retainCount:
2516  case OMF_self:
2517  case OMF_initialize:
2518  case OMF_performSelector:
2519    // Mismatches for these methods don't change ownership
2520    // conventions, so we don't care.
2521    return false;
2522
2523  case OMF_init: familySelector = F_init; break;
2524  case OMF_alloc: familySelector = F_alloc; break;
2525  case OMF_copy: familySelector = F_copy; break;
2526  case OMF_mutableCopy: familySelector = F_mutableCopy; break;
2527  case OMF_new: familySelector = F_new; break;
2528  }
2529
2530  enum ReasonSelector { R_NonObjectReturn, R_UnrelatedReturn };
2531  ReasonSelector reasonSelector;
2532
2533  // The only reason these methods don't fall within their families is
2534  // due to unusual result types.
2535  if (unmatched->getReturnType()->isObjCObjectPointerType()) {
2536    reasonSelector = R_UnrelatedReturn;
2537  } else {
2538    reasonSelector = R_NonObjectReturn;
2539  }
2540
2541  S.Diag(impl->getLocation(), errorID) << int(familySelector) << int(reasonSelector);
2542  S.Diag(decl->getLocation(), noteID) << int(familySelector) << int(reasonSelector);
2543
2544  return true;
2545}
2546
2547void Sema::WarnConflictingTypedMethods(ObjCMethodDecl *ImpMethodDecl,
2548                                       ObjCMethodDecl *MethodDecl,
2549                                       bool IsProtocolMethodDecl) {
2550  if (getLangOpts().ObjCAutoRefCount &&
2551      checkMethodFamilyMismatch(*this, ImpMethodDecl, MethodDecl))
2552    return;
2553
2554  CheckMethodOverrideReturn(*this, ImpMethodDecl, MethodDecl,
2555                            IsProtocolMethodDecl, false,
2556                            true);
2557
2558  for (ObjCMethodDecl::param_iterator IM = ImpMethodDecl->param_begin(),
2559       IF = MethodDecl->param_begin(), EM = ImpMethodDecl->param_end(),
2560       EF = MethodDecl->param_end();
2561       IM != EM && IF != EF; ++IM, ++IF) {
2562    CheckMethodOverrideParam(*this, ImpMethodDecl, MethodDecl, *IM, *IF,
2563                             IsProtocolMethodDecl, false, true);
2564  }
2565
2566  if (ImpMethodDecl->isVariadic() != MethodDecl->isVariadic()) {
2567    Diag(ImpMethodDecl->getLocation(),
2568         diag::warn_conflicting_variadic);
2569    Diag(MethodDecl->getLocation(), diag::note_previous_declaration);
2570  }
2571}
2572
2573void Sema::CheckConflictingOverridingMethod(ObjCMethodDecl *Method,
2574                                       ObjCMethodDecl *Overridden,
2575                                       bool IsProtocolMethodDecl) {
2576
2577  CheckMethodOverrideReturn(*this, Method, Overridden,
2578                            IsProtocolMethodDecl, true,
2579                            true);
2580
2581  for (ObjCMethodDecl::param_iterator IM = Method->param_begin(),
2582       IF = Overridden->param_begin(), EM = Method->param_end(),
2583       EF = Overridden->param_end();
2584       IM != EM && IF != EF; ++IM, ++IF) {
2585    CheckMethodOverrideParam(*this, Method, Overridden, *IM, *IF,
2586                             IsProtocolMethodDecl, true, true);
2587  }
2588
2589  if (Method->isVariadic() != Overridden->isVariadic()) {
2590    Diag(Method->getLocation(),
2591         diag::warn_conflicting_overriding_variadic);
2592    Diag(Overridden->getLocation(), diag::note_previous_declaration);
2593  }
2594}
2595
2596/// WarnExactTypedMethods - This routine issues a warning if method
2597/// implementation declaration matches exactly that of its declaration.
2598void Sema::WarnExactTypedMethods(ObjCMethodDecl *ImpMethodDecl,
2599                                 ObjCMethodDecl *MethodDecl,
2600                                 bool IsProtocolMethodDecl) {
2601  // don't issue warning when protocol method is optional because primary
2602  // class is not required to implement it and it is safe for protocol
2603  // to implement it.
2604  if (MethodDecl->getImplementationControl() == ObjCMethodDecl::Optional)
2605    return;
2606  // don't issue warning when primary class's method is
2607  // depecated/unavailable.
2608  if (MethodDecl->hasAttr<UnavailableAttr>() ||
2609      MethodDecl->hasAttr<DeprecatedAttr>())
2610    return;
2611
2612  bool match = CheckMethodOverrideReturn(*this, ImpMethodDecl, MethodDecl,
2613                                      IsProtocolMethodDecl, false, false);
2614  if (match)
2615    for (ObjCMethodDecl::param_iterator IM = ImpMethodDecl->param_begin(),
2616         IF = MethodDecl->param_begin(), EM = ImpMethodDecl->param_end(),
2617         EF = MethodDecl->param_end();
2618         IM != EM && IF != EF; ++IM, ++IF) {
2619      match = CheckMethodOverrideParam(*this, ImpMethodDecl, MethodDecl,
2620                                       *IM, *IF,
2621                                       IsProtocolMethodDecl, false, false);
2622      if (!match)
2623        break;
2624    }
2625  if (match)
2626    match = (ImpMethodDecl->isVariadic() == MethodDecl->isVariadic());
2627  if (match)
2628    match = !(MethodDecl->isClassMethod() &&
2629              MethodDecl->getSelector() == GetNullarySelector("load", Context));
2630
2631  if (match) {
2632    Diag(ImpMethodDecl->getLocation(),
2633         diag::warn_category_method_impl_match);
2634    Diag(MethodDecl->getLocation(), diag::note_method_declared_at)
2635      << MethodDecl->getDeclName();
2636  }
2637}
2638
2639/// FIXME: Type hierarchies in Objective-C can be deep. We could most likely
2640/// improve the efficiency of selector lookups and type checking by associating
2641/// with each protocol / interface / category the flattened instance tables. If
2642/// we used an immutable set to keep the table then it wouldn't add significant
2643/// memory cost and it would be handy for lookups.
2644
2645typedef llvm::DenseSet<IdentifierInfo*> ProtocolNameSet;
2646typedef std::unique_ptr<ProtocolNameSet> LazyProtocolNameSet;
2647
2648static void findProtocolsWithExplicitImpls(const ObjCProtocolDecl *PDecl,
2649                                           ProtocolNameSet &PNS) {
2650  if (PDecl->hasAttr<ObjCExplicitProtocolImplAttr>())
2651    PNS.insert(PDecl->getIdentifier());
2652  for (const auto *PI : PDecl->protocols())
2653    findProtocolsWithExplicitImpls(PI, PNS);
2654}
2655
2656/// Recursively populates a set with all conformed protocols in a class
2657/// hierarchy that have the 'objc_protocol_requires_explicit_implementation'
2658/// attribute.
2659static void findProtocolsWithExplicitImpls(const ObjCInterfaceDecl *Super,
2660                                           ProtocolNameSet &PNS) {
2661  if (!Super)
2662    return;
2663
2664  for (const auto *I : Super->all_referenced_protocols())
2665    findProtocolsWithExplicitImpls(I, PNS);
2666
2667  findProtocolsWithExplicitImpls(Super->getSuperClass(), PNS);
2668}
2669
2670/// CheckProtocolMethodDefs - This routine checks unimplemented methods
2671/// Declared in protocol, and those referenced by it.
2672static void CheckProtocolMethodDefs(Sema &S,
2673                                    SourceLocation ImpLoc,
2674                                    ObjCProtocolDecl *PDecl,
2675                                    bool& IncompleteImpl,
2676                                    const Sema::SelectorSet &InsMap,
2677                                    const Sema::SelectorSet &ClsMap,
2678                                    ObjCContainerDecl *CDecl,
2679                                    LazyProtocolNameSet &ProtocolsExplictImpl) {
2680  ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(CDecl);
2681  ObjCInterfaceDecl *IDecl = C ? C->getClassInterface()
2682                               : dyn_cast<ObjCInterfaceDecl>(CDecl);
2683  assert (IDecl && "CheckProtocolMethodDefs - IDecl is null");
2684
2685  ObjCInterfaceDecl *Super = IDecl->getSuperClass();
2686  ObjCInterfaceDecl *NSIDecl = nullptr;
2687
2688  // If this protocol is marked 'objc_protocol_requires_explicit_implementation'
2689  // then we should check if any class in the super class hierarchy also
2690  // conforms to this protocol, either directly or via protocol inheritance.
2691  // If so, we can skip checking this protocol completely because we
2692  // know that a parent class already satisfies this protocol.
2693  //
2694  // Note: we could generalize this logic for all protocols, and merely
2695  // add the limit on looking at the super class chain for just
2696  // specially marked protocols.  This may be a good optimization.  This
2697  // change is restricted to 'objc_protocol_requires_explicit_implementation'
2698  // protocols for now for controlled evaluation.
2699  if (PDecl->hasAttr<ObjCExplicitProtocolImplAttr>()) {
2700    if (!ProtocolsExplictImpl) {
2701      ProtocolsExplictImpl.reset(new ProtocolNameSet);
2702      findProtocolsWithExplicitImpls(Super, *ProtocolsExplictImpl);
2703    }
2704    if (ProtocolsExplictImpl->find(PDecl->getIdentifier()) !=
2705        ProtocolsExplictImpl->end())
2706      return;
2707
2708    // If no super class conforms to the protocol, we should not search
2709    // for methods in the super class to implicitly satisfy the protocol.
2710    Super = nullptr;
2711  }
2712
2713  if (S.getLangOpts().ObjCRuntime.isNeXTFamily()) {
2714    // check to see if class implements forwardInvocation method and objects
2715    // of this class are derived from 'NSProxy' so that to forward requests
2716    // from one object to another.
2717    // Under such conditions, which means that every method possible is
2718    // implemented in the class, we should not issue "Method definition not
2719    // found" warnings.
2720    // FIXME: Use a general GetUnarySelector method for this.
2721    IdentifierInfo* II = &S.Context.Idents.get("forwardInvocation");
2722    Selector fISelector = S.Context.Selectors.getSelector(1, &II);
2723    if (InsMap.count(fISelector))
2724      // Is IDecl derived from 'NSProxy'? If so, no instance methods
2725      // need be implemented in the implementation.
2726      NSIDecl = IDecl->lookupInheritedClass(&S.Context.Idents.get("NSProxy"));
2727  }
2728
2729  // If this is a forward protocol declaration, get its definition.
2730  if (!PDecl->isThisDeclarationADefinition() &&
2731      PDecl->getDefinition())
2732    PDecl = PDecl->getDefinition();
2733
2734  // If a method lookup fails locally we still need to look and see if
2735  // the method was implemented by a base class or an inherited
2736  // protocol. This lookup is slow, but occurs rarely in correct code
2737  // and otherwise would terminate in a warning.
2738
2739  // check unimplemented instance methods.
2740  if (!NSIDecl)
2741    for (auto *method : PDecl->instance_methods()) {
2742      if (method->getImplementationControl() != ObjCMethodDecl::Optional &&
2743          !method->isPropertyAccessor() &&
2744          !InsMap.count(method->getSelector()) &&
2745          (!Super || !Super->lookupMethod(method->getSelector(),
2746                                          true /* instance */,
2747                                          false /* shallowCategory */,
2748                                          true /* followsSuper */,
2749                                          nullptr /* category */))) {
2750            // If a method is not implemented in the category implementation but
2751            // has been declared in its primary class, superclass,
2752            // or in one of their protocols, no need to issue the warning.
2753            // This is because method will be implemented in the primary class
2754            // or one of its super class implementation.
2755
2756            // Ugly, but necessary. Method declared in protocol might have
2757            // have been synthesized due to a property declared in the class which
2758            // uses the protocol.
2759            if (ObjCMethodDecl *MethodInClass =
2760                  IDecl->lookupMethod(method->getSelector(),
2761                                      true /* instance */,
2762                                      true /* shallowCategoryLookup */,
2763                                      false /* followSuper */))
2764              if (C || MethodInClass->isPropertyAccessor())
2765                continue;
2766            unsigned DIAG = diag::warn_unimplemented_protocol_method;
2767            if (!S.Diags.isIgnored(DIAG, ImpLoc)) {
2768              WarnUndefinedMethod(S, ImpLoc, method, IncompleteImpl, DIAG,
2769                                  PDecl);
2770            }
2771          }
2772    }
2773  // check unimplemented class methods
2774  for (auto *method : PDecl->class_methods()) {
2775    if (method->getImplementationControl() != ObjCMethodDecl::Optional &&
2776        !ClsMap.count(method->getSelector()) &&
2777        (!Super || !Super->lookupMethod(method->getSelector(),
2778                                        false /* class method */,
2779                                        false /* shallowCategoryLookup */,
2780                                        true  /* followSuper */,
2781                                        nullptr /* category */))) {
2782      // See above comment for instance method lookups.
2783      if (C && IDecl->lookupMethod(method->getSelector(),
2784                                   false /* class */,
2785                                   true /* shallowCategoryLookup */,
2786                                   false /* followSuper */))
2787        continue;
2788
2789      unsigned DIAG = diag::warn_unimplemented_protocol_method;
2790      if (!S.Diags.isIgnored(DIAG, ImpLoc)) {
2791        WarnUndefinedMethod(S, ImpLoc, method, IncompleteImpl, DIAG, PDecl);
2792      }
2793    }
2794  }
2795  // Check on this protocols's referenced protocols, recursively.
2796  for (auto *PI : PDecl->protocols())
2797    CheckProtocolMethodDefs(S, ImpLoc, PI, IncompleteImpl, InsMap, ClsMap,
2798                            CDecl, ProtocolsExplictImpl);
2799}
2800
2801/// MatchAllMethodDeclarations - Check methods declared in interface
2802/// or protocol against those declared in their implementations.
2803///
2804void Sema::MatchAllMethodDeclarations(const SelectorSet &InsMap,
2805                                      const SelectorSet &ClsMap,
2806                                      SelectorSet &InsMapSeen,
2807                                      SelectorSet &ClsMapSeen,
2808                                      ObjCImplDecl* IMPDecl,
2809                                      ObjCContainerDecl* CDecl,
2810                                      bool &IncompleteImpl,
2811                                      bool ImmediateClass,
2812                                      bool WarnCategoryMethodImpl) {
2813  // Check and see if instance methods in class interface have been
2814  // implemented in the implementation class. If so, their types match.
2815  for (auto *I : CDecl->instance_methods()) {
2816    if (!InsMapSeen.insert(I->getSelector()).second)
2817      continue;
2818    if (!I->isPropertyAccessor() &&
2819        !InsMap.count(I->getSelector())) {
2820      if (ImmediateClass)
2821        WarnUndefinedMethod(*this, IMPDecl->getLocation(), I, IncompleteImpl,
2822                            diag::warn_undef_method_impl);
2823      continue;
2824    } else {
2825      ObjCMethodDecl *ImpMethodDecl =
2826        IMPDecl->getInstanceMethod(I->getSelector());
2827      assert(CDecl->getInstanceMethod(I->getSelector(), true/*AllowHidden*/) &&
2828             "Expected to find the method through lookup as well");
2829      // ImpMethodDecl may be null as in a @dynamic property.
2830      if (ImpMethodDecl) {
2831        // Skip property accessor function stubs.
2832        if (ImpMethodDecl->isSynthesizedAccessorStub())
2833          continue;
2834        if (!WarnCategoryMethodImpl)
2835          WarnConflictingTypedMethods(ImpMethodDecl, I,
2836                                      isa<ObjCProtocolDecl>(CDecl));
2837        else if (!I->isPropertyAccessor())
2838          WarnExactTypedMethods(ImpMethodDecl, I, isa<ObjCProtocolDecl>(CDecl));
2839      }
2840    }
2841  }
2842
2843  // Check and see if class methods in class interface have been
2844  // implemented in the implementation class. If so, their types match.
2845  for (auto *I : CDecl->class_methods()) {
2846    if (!ClsMapSeen.insert(I->getSelector()).second)
2847      continue;
2848    if (!I->isPropertyAccessor() &&
2849        !ClsMap.count(I->getSelector())) {
2850      if (ImmediateClass)
2851        WarnUndefinedMethod(*this, IMPDecl->getLocation(), I, IncompleteImpl,
2852                            diag::warn_undef_method_impl);
2853    } else {
2854      ObjCMethodDecl *ImpMethodDecl =
2855        IMPDecl->getClassMethod(I->getSelector());
2856      assert(CDecl->getClassMethod(I->getSelector(), true/*AllowHidden*/) &&
2857             "Expected to find the method through lookup as well");
2858      // ImpMethodDecl may be null as in a @dynamic property.
2859      if (ImpMethodDecl) {
2860        // Skip property accessor function stubs.
2861        if (ImpMethodDecl->isSynthesizedAccessorStub())
2862          continue;
2863        if (!WarnCategoryMethodImpl)
2864          WarnConflictingTypedMethods(ImpMethodDecl, I,
2865                                      isa<ObjCProtocolDecl>(CDecl));
2866        else if (!I->isPropertyAccessor())
2867          WarnExactTypedMethods(ImpMethodDecl, I, isa<ObjCProtocolDecl>(CDecl));
2868      }
2869    }
2870  }
2871
2872  if (ObjCProtocolDecl *PD = dyn_cast<ObjCProtocolDecl> (CDecl)) {
2873    // Also, check for methods declared in protocols inherited by
2874    // this protocol.
2875    for (auto *PI : PD->protocols())
2876      MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2877                                 IMPDecl, PI, IncompleteImpl, false,
2878                                 WarnCategoryMethodImpl);
2879  }
2880
2881  if (ObjCInterfaceDecl *I = dyn_cast<ObjCInterfaceDecl> (CDecl)) {
2882    // when checking that methods in implementation match their declaration,
2883    // i.e. when WarnCategoryMethodImpl is false, check declarations in class
2884    // extension; as well as those in categories.
2885    if (!WarnCategoryMethodImpl) {
2886      for (auto *Cat : I->visible_categories())
2887        MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2888                                   IMPDecl, Cat, IncompleteImpl,
2889                                   ImmediateClass && Cat->IsClassExtension(),
2890                                   WarnCategoryMethodImpl);
2891    } else {
2892      // Also methods in class extensions need be looked at next.
2893      for (auto *Ext : I->visible_extensions())
2894        MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2895                                   IMPDecl, Ext, IncompleteImpl, false,
2896                                   WarnCategoryMethodImpl);
2897    }
2898
2899    // Check for any implementation of a methods declared in protocol.
2900    for (auto *PI : I->all_referenced_protocols())
2901      MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2902                                 IMPDecl, PI, IncompleteImpl, false,
2903                                 WarnCategoryMethodImpl);
2904
2905    // FIXME. For now, we are not checking for exact match of methods
2906    // in category implementation and its primary class's super class.
2907    if (!WarnCategoryMethodImpl && I->getSuperClass())
2908      MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2909                                 IMPDecl,
2910                                 I->getSuperClass(), IncompleteImpl, false);
2911  }
2912}
2913
2914/// CheckCategoryVsClassMethodMatches - Checks that methods implemented in
2915/// category matches with those implemented in its primary class and
2916/// warns each time an exact match is found.
2917void Sema::CheckCategoryVsClassMethodMatches(
2918                                  ObjCCategoryImplDecl *CatIMPDecl) {
2919  // Get category's primary class.
2920  ObjCCategoryDecl *CatDecl = CatIMPDecl->getCategoryDecl();
2921  if (!CatDecl)
2922    return;
2923  ObjCInterfaceDecl *IDecl = CatDecl->getClassInterface();
2924  if (!IDecl)
2925    return;
2926  ObjCInterfaceDecl *SuperIDecl = IDecl->getSuperClass();
2927  SelectorSet InsMap, ClsMap;
2928
2929  for (const auto *I : CatIMPDecl->instance_methods()) {
2930    Selector Sel = I->getSelector();
2931    // When checking for methods implemented in the category, skip over
2932    // those declared in category class's super class. This is because
2933    // the super class must implement the method.
2934    if (SuperIDecl && SuperIDecl->lookupMethod(Sel, true))
2935      continue;
2936    InsMap.insert(Sel);
2937  }
2938
2939  for (const auto *I : CatIMPDecl->class_methods()) {
2940    Selector Sel = I->getSelector();
2941    if (SuperIDecl && SuperIDecl->lookupMethod(Sel, false))
2942      continue;
2943    ClsMap.insert(Sel);
2944  }
2945  if (InsMap.empty() && ClsMap.empty())
2946    return;
2947
2948  SelectorSet InsMapSeen, ClsMapSeen;
2949  bool IncompleteImpl = false;
2950  MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
2951                             CatIMPDecl, IDecl,
2952                             IncompleteImpl, false,
2953                             true /*WarnCategoryMethodImpl*/);
2954}
2955
2956void Sema::ImplMethodsVsClassMethods(Scope *S, ObjCImplDecl* IMPDecl,
2957                                     ObjCContainerDecl* CDecl,
2958                                     bool IncompleteImpl) {
2959  SelectorSet InsMap;
2960  // Check and see if instance methods in class interface have been
2961  // implemented in the implementation class.
2962  for (const auto *I : IMPDecl->instance_methods())
2963    InsMap.insert(I->getSelector());
2964
2965  // Add the selectors for getters/setters of @dynamic properties.
2966  for (const auto *PImpl : IMPDecl->property_impls()) {
2967    // We only care about @dynamic implementations.
2968    if (PImpl->getPropertyImplementation() != ObjCPropertyImplDecl::Dynamic)
2969      continue;
2970
2971    const auto *P = PImpl->getPropertyDecl();
2972    if (!P) continue;
2973
2974    InsMap.insert(P->getGetterName());
2975    if (!P->getSetterName().isNull())
2976      InsMap.insert(P->getSetterName());
2977  }
2978
2979  // Check and see if properties declared in the interface have either 1)
2980  // an implementation or 2) there is a @synthesize/@dynamic implementation
2981  // of the property in the @implementation.
2982  if (const ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(CDecl)) {
2983    bool SynthesizeProperties = LangOpts.ObjCDefaultSynthProperties &&
2984                                LangOpts.ObjCRuntime.isNonFragile() &&
2985                                !IDecl->isObjCRequiresPropertyDefs();
2986    DiagnoseUnimplementedProperties(S, IMPDecl, CDecl, SynthesizeProperties);
2987  }
2988
2989  // Diagnose null-resettable synthesized setters.
2990  diagnoseNullResettableSynthesizedSetters(IMPDecl);
2991
2992  SelectorSet ClsMap;
2993  for (const auto *I : IMPDecl->class_methods())
2994    ClsMap.insert(I->getSelector());
2995
2996  // Check for type conflict of methods declared in a class/protocol and
2997  // its implementation; if any.
2998  SelectorSet InsMapSeen, ClsMapSeen;
2999  MatchAllMethodDeclarations(InsMap, ClsMap, InsMapSeen, ClsMapSeen,
3000                             IMPDecl, CDecl,
3001                             IncompleteImpl, true);
3002
3003  // check all methods implemented in category against those declared
3004  // in its primary class.
3005  if (ObjCCategoryImplDecl *CatDecl =
3006        dyn_cast<ObjCCategoryImplDecl>(IMPDecl))
3007    CheckCategoryVsClassMethodMatches(CatDecl);
3008
3009  // Check the protocol list for unimplemented methods in the @implementation
3010  // class.
3011  // Check and see if class methods in class interface have been
3012  // implemented in the implementation class.
3013
3014  LazyProtocolNameSet ExplicitImplProtocols;
3015
3016  if (ObjCInterfaceDecl *I = dyn_cast<ObjCInterfaceDecl> (CDecl)) {
3017    for (auto *PI : I->all_referenced_protocols())
3018      CheckProtocolMethodDefs(*this, IMPDecl->getLocation(), PI, IncompleteImpl,
3019                              InsMap, ClsMap, I, ExplicitImplProtocols);
3020  } else if (ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(CDecl)) {
3021    // For extended class, unimplemented methods in its protocols will
3022    // be reported in the primary class.
3023    if (!C->IsClassExtension()) {
3024      for (auto *P : C->protocols())
3025        CheckProtocolMethodDefs(*this, IMPDecl->getLocation(), P,
3026                                IncompleteImpl, InsMap, ClsMap, CDecl,
3027                                ExplicitImplProtocols);
3028      DiagnoseUnimplementedProperties(S, IMPDecl, CDecl,
3029                                      /*SynthesizeProperties=*/false);
3030    }
3031  } else
3032    llvm_unreachable("invalid ObjCContainerDecl type.");
3033}
3034
3035Sema::DeclGroupPtrTy
3036Sema::ActOnForwardClassDeclaration(SourceLocation AtClassLoc,
3037                                   IdentifierInfo **IdentList,
3038                                   SourceLocation *IdentLocs,
3039                                   ArrayRef<ObjCTypeParamList *> TypeParamLists,
3040                                   unsigned NumElts) {
3041  SmallVector<Decl *, 8> DeclsInGroup;
3042  for (unsigned i = 0; i != NumElts; ++i) {
3043    // Check for another declaration kind with the same name.
3044    NamedDecl *PrevDecl
3045      = LookupSingleName(TUScope, IdentList[i], IdentLocs[i],
3046                         LookupOrdinaryName, forRedeclarationInCurContext());
3047    if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
3048      // GCC apparently allows the following idiom:
3049      //
3050      // typedef NSObject < XCElementTogglerP > XCElementToggler;
3051      // @class XCElementToggler;
3052      //
3053      // Here we have chosen to ignore the forward class declaration
3054      // with a warning. Since this is the implied behavior.
3055      TypedefNameDecl *TDD = dyn_cast<TypedefNameDecl>(PrevDecl);
3056      if (!TDD || !TDD->getUnderlyingType()->isObjCObjectType()) {
3057        Diag(AtClassLoc, diag::err_redefinition_different_kind) << IdentList[i];
3058        Diag(PrevDecl->getLocation(), diag::note_previous_definition);
3059      } else {
3060        // a forward class declaration matching a typedef name of a class refers
3061        // to the underlying class. Just ignore the forward class with a warning
3062        // as this will force the intended behavior which is to lookup the
3063        // typedef name.
3064        if (isa<ObjCObjectType>(TDD->getUnderlyingType())) {
3065          Diag(AtClassLoc, diag::warn_forward_class_redefinition)
3066              << IdentList[i];
3067          Diag(PrevDecl->getLocation(), diag::note_previous_definition);
3068          continue;
3069        }
3070      }
3071    }
3072
3073    // Create a declaration to describe this forward declaration.
3074    ObjCInterfaceDecl *PrevIDecl
3075      = dyn_cast_or_null<ObjCInterfaceDecl>(PrevDecl);
3076
3077    IdentifierInfo *ClassName = IdentList[i];
3078    if (PrevIDecl && PrevIDecl->getIdentifier() != ClassName) {
3079      // A previous decl with a different name is because of
3080      // @compatibility_alias, for example:
3081      // \code
3082      //   @class NewImage;
3083      //   @compatibility_alias OldImage NewImage;
3084      // \endcode
3085      // A lookup for 'OldImage' will return the 'NewImage' decl.
3086      //
3087      // In such a case use the real declaration name, instead of the alias one,
3088      // otherwise we will break IdentifierResolver and redecls-chain invariants.
3089      // FIXME: If necessary, add a bit to indicate that this ObjCInterfaceDecl
3090      // has been aliased.
3091      ClassName = PrevIDecl->getIdentifier();
3092    }
3093
3094    // If this forward declaration has type parameters, compare them with the
3095    // type parameters of the previous declaration.
3096    ObjCTypeParamList *TypeParams = TypeParamLists[i];
3097    if (PrevIDecl && TypeParams) {
3098      if (ObjCTypeParamList *PrevTypeParams = PrevIDecl->getTypeParamList()) {
3099        // Check for consistency with the previous declaration.
3100        if (checkTypeParamListConsistency(
3101              *this, PrevTypeParams, TypeParams,
3102              TypeParamListContext::ForwardDeclaration)) {
3103          TypeParams = nullptr;
3104        }
3105      } else if (ObjCInterfaceDecl *Def = PrevIDecl->getDefinition()) {
3106        // The @interface does not have type parameters. Complain.
3107        Diag(IdentLocs[i], diag::err_objc_parameterized_forward_class)
3108          << ClassName
3109          << TypeParams->getSourceRange();
3110        Diag(Def->getLocation(), diag::note_defined_here)
3111          << ClassName;
3112
3113        TypeParams = nullptr;
3114      }
3115    }
3116
3117    ObjCInterfaceDecl *IDecl
3118      = ObjCInterfaceDecl::Create(Context, CurContext, AtClassLoc,
3119                                  ClassName, TypeParams, PrevIDecl,
3120                                  IdentLocs[i]);
3121    IDecl->setAtEndRange(IdentLocs[i]);
3122
3123    PushOnScopeChains(IDecl, TUScope);
3124    CheckObjCDeclScope(IDecl);
3125    DeclsInGroup.push_back(IDecl);
3126  }
3127
3128  return BuildDeclaratorGroup(DeclsInGroup);
3129}
3130
3131static bool tryMatchRecordTypes(ASTContext &Context,
3132                                Sema::MethodMatchStrategy strategy,
3133                                const Type *left, const Type *right);
3134
3135static bool matchTypes(ASTContext &Context, Sema::MethodMatchStrategy strategy,
3136                       QualType leftQT, QualType rightQT) {
3137  const Type *left =
3138    Context.getCanonicalType(leftQT).getUnqualifiedType().getTypePtr();
3139  const Type *right =
3140    Context.getCanonicalType(rightQT).getUnqualifiedType().getTypePtr();
3141
3142  if (left == right) return true;
3143
3144  // If we're doing a strict match, the types have to match exactly.
3145  if (strategy == Sema::MMS_strict) return false;
3146
3147  if (left->isIncompleteType() || right->isIncompleteType()) return false;
3148
3149  // Otherwise, use this absurdly complicated algorithm to try to
3150  // validate the basic, low-level compatibility of the two types.
3151
3152  // As a minimum, require the sizes and alignments to match.
3153  TypeInfo LeftTI = Context.getTypeInfo(left);
3154  TypeInfo RightTI = Context.getTypeInfo(right);
3155  if (LeftTI.Width != RightTI.Width)
3156    return false;
3157
3158  if (LeftTI.Align != RightTI.Align)
3159    return false;
3160
3161  // Consider all the kinds of non-dependent canonical types:
3162  // - functions and arrays aren't possible as return and parameter types
3163
3164  // - vector types of equal size can be arbitrarily mixed
3165  if (isa<VectorType>(left)) return isa<VectorType>(right);
3166  if (isa<VectorType>(right)) return false;
3167
3168  // - references should only match references of identical type
3169  // - structs, unions, and Objective-C objects must match more-or-less
3170  //   exactly
3171  // - everything else should be a scalar
3172  if (!left->isScalarType() || !right->isScalarType())
3173    return tryMatchRecordTypes(Context, strategy, left, right);
3174
3175  // Make scalars agree in kind, except count bools as chars, and group
3176  // all non-member pointers together.
3177  Type::ScalarTypeKind leftSK = left->getScalarTypeKind();
3178  Type::ScalarTypeKind rightSK = right->getScalarTypeKind();
3179  if (leftSK == Type::STK_Bool) leftSK = Type::STK_Integral;
3180  if (rightSK == Type::STK_Bool) rightSK = Type::STK_Integral;
3181  if (leftSK == Type::STK_CPointer || leftSK == Type::STK_BlockPointer)
3182    leftSK = Type::STK_ObjCObjectPointer;
3183  if (rightSK == Type::STK_CPointer || rightSK == Type::STK_BlockPointer)
3184    rightSK = Type::STK_ObjCObjectPointer;
3185
3186  // Note that data member pointers and function member pointers don't
3187  // intermix because of the size differences.
3188
3189  return (leftSK == rightSK);
3190}
3191
3192static bool tryMatchRecordTypes(ASTContext &Context,
3193                                Sema::MethodMatchStrategy strategy,
3194                                const Type *lt, const Type *rt) {
3195  assert(lt && rt && lt != rt);
3196
3197  if (!isa<RecordType>(lt) || !isa<RecordType>(rt)) return false;
3198  RecordDecl *left = cast<RecordType>(lt)->getDecl();
3199  RecordDecl *right = cast<RecordType>(rt)->getDecl();
3200
3201  // Require union-hood to match.
3202  if (left->isUnion() != right->isUnion()) return false;
3203
3204  // Require an exact match if either is non-POD.
3205  if ((isa<CXXRecordDecl>(left) && !cast<CXXRecordDecl>(left)->isPOD()) ||
3206      (isa<CXXRecordDecl>(right) && !cast<CXXRecordDecl>(right)->isPOD()))
3207    return false;
3208
3209  // Require size and alignment to match.
3210  TypeInfo LeftTI = Context.getTypeInfo(lt);
3211  TypeInfo RightTI = Context.getTypeInfo(rt);
3212  if (LeftTI.Width != RightTI.Width)
3213    return false;
3214
3215  if (LeftTI.Align != RightTI.Align)
3216    return false;
3217
3218  // Require fields to match.
3219  RecordDecl::field_iterator li = left->field_begin(), le = left->field_end();
3220  RecordDecl::field_iterator ri = right->field_begin(), re = right->field_end();
3221  for (; li != le && ri != re; ++li, ++ri) {
3222    if (!matchTypes(Context, strategy, li->getType(), ri->getType()))
3223      return false;
3224  }
3225  return (li == le && ri == re);
3226}
3227
3228/// MatchTwoMethodDeclarations - Checks that two methods have matching type and
3229/// returns true, or false, accordingly.
3230/// TODO: Handle protocol list; such as id<p1,p2> in type comparisons
3231bool Sema::MatchTwoMethodDeclarations(const ObjCMethodDecl *left,
3232                                      const ObjCMethodDecl *right,
3233                                      MethodMatchStrategy strategy) {
3234  if (!matchTypes(Context, strategy, left->getReturnType(),
3235                  right->getReturnType()))
3236    return false;
3237
3238  // If either is hidden, it is not considered to match.
3239  if (left->isHidden() || right->isHidden())
3240    return false;
3241
3242  if (left->isDirectMethod() != right->isDirectMethod())
3243    return false;
3244
3245  if (getLangOpts().ObjCAutoRefCount &&
3246      (left->hasAttr<NSReturnsRetainedAttr>()
3247         != right->hasAttr<NSReturnsRetainedAttr>() ||
3248       left->hasAttr<NSConsumesSelfAttr>()
3249         != right->hasAttr<NSConsumesSelfAttr>()))
3250    return false;
3251
3252  ObjCMethodDecl::param_const_iterator
3253    li = left->param_begin(), le = left->param_end(), ri = right->param_begin(),
3254    re = right->param_end();
3255
3256  for (; li != le && ri != re; ++li, ++ri) {
3257    assert(ri != right->param_end() && "Param mismatch");
3258    const ParmVarDecl *lparm = *li, *rparm = *ri;
3259
3260    if (!matchTypes(Context, strategy, lparm->getType(), rparm->getType()))
3261      return false;
3262
3263    if (getLangOpts().ObjCAutoRefCount &&
3264        lparm->hasAttr<NSConsumedAttr>() != rparm->hasAttr<NSConsumedAttr>())
3265      return false;
3266  }
3267  return true;
3268}
3269
3270static bool isMethodContextSameForKindofLookup(ObjCMethodDecl *Method,
3271                                               ObjCMethodDecl *MethodInList) {
3272  auto *MethodProtocol = dyn_cast<ObjCProtocolDecl>(Method->getDeclContext());
3273  auto *MethodInListProtocol =
3274      dyn_cast<ObjCProtocolDecl>(MethodInList->getDeclContext());
3275  // If this method belongs to a protocol but the method in list does not, or
3276  // vice versa, we say the context is not the same.
3277  if ((MethodProtocol && !MethodInListProtocol) ||
3278      (!MethodProtocol && MethodInListProtocol))
3279    return false;
3280
3281  if (MethodProtocol && MethodInListProtocol)
3282    return true;
3283
3284  ObjCInterfaceDecl *MethodInterface = Method->getClassInterface();
3285  ObjCInterfaceDecl *MethodInListInterface =
3286      MethodInList->getClassInterface();
3287  return MethodInterface == MethodInListInterface;
3288}
3289
3290void Sema::addMethodToGlobalList(ObjCMethodList *List,
3291                                 ObjCMethodDecl *Method) {
3292  // Record at the head of the list whether there were 0, 1, or >= 2 methods
3293  // inside categories.
3294  if (ObjCCategoryDecl *CD =
3295          dyn_cast<ObjCCategoryDecl>(Method->getDeclContext()))
3296    if (!CD->IsClassExtension() && List->getBits() < 2)
3297      List->setBits(List->getBits() + 1);
3298
3299  // If the list is empty, make it a singleton list.
3300  if (List->getMethod() == nullptr) {
3301    List->setMethod(Method);
3302    List->setNext(nullptr);
3303    return;
3304  }
3305
3306  // We've seen a method with this name, see if we have already seen this type
3307  // signature.
3308  ObjCMethodList *Previous = List;
3309  ObjCMethodList *ListWithSameDeclaration = nullptr;
3310  for (; List; Previous = List, List = List->getNext()) {
3311    // If we are building a module, keep all of the methods.
3312    if (getLangOpts().isCompilingModule())
3313      continue;
3314
3315    bool SameDeclaration = MatchTwoMethodDeclarations(Method,
3316                                                      List->getMethod());
3317    // Looking for method with a type bound requires the correct context exists.
3318    // We need to insert a method into the list if the context is different.
3319    // If the method's declaration matches the list
3320    // a> the method belongs to a different context: we need to insert it, in
3321    //    order to emit the availability message, we need to prioritize over
3322    //    availability among the methods with the same declaration.
3323    // b> the method belongs to the same context: there is no need to insert a
3324    //    new entry.
3325    // If the method's declaration does not match the list, we insert it to the
3326    // end.
3327    if (!SameDeclaration ||
3328        !isMethodContextSameForKindofLookup(Method, List->getMethod())) {
3329      // Even if two method types do not match, we would like to say
3330      // there is more than one declaration so unavailability/deprecated
3331      // warning is not too noisy.
3332      if (!Method->isDefined())
3333        List->setHasMoreThanOneDecl(true);
3334
3335      // For methods with the same declaration, the one that is deprecated
3336      // should be put in the front for better diagnostics.
3337      if (Method->isDeprecated() && SameDeclaration &&
3338          !ListWithSameDeclaration && !List->getMethod()->isDeprecated())
3339        ListWithSameDeclaration = List;
3340
3341      if (Method->isUnavailable() && SameDeclaration &&
3342          !ListWithSameDeclaration &&
3343          List->getMethod()->getAvailability() < AR_Deprecated)
3344        ListWithSameDeclaration = List;
3345      continue;
3346    }
3347
3348    ObjCMethodDecl *PrevObjCMethod = List->getMethod();
3349
3350    // Propagate the 'defined' bit.
3351    if (Method->isDefined())
3352      PrevObjCMethod->setDefined(true);
3353    else {
3354      // Objective-C doesn't allow an @interface for a class after its
3355      // @implementation. So if Method is not defined and there already is
3356      // an entry for this type signature, Method has to be for a different
3357      // class than PrevObjCMethod.
3358      List->setHasMoreThanOneDecl(true);
3359    }
3360
3361    // If a method is deprecated, push it in the global pool.
3362    // This is used for better diagnostics.
3363    if (Method->isDeprecated()) {
3364      if (!PrevObjCMethod->isDeprecated())
3365        List->setMethod(Method);
3366    }
3367    // If the new method is unavailable, push it into global pool
3368    // unless previous one is deprecated.
3369    if (Method->isUnavailable()) {
3370      if (PrevObjCMethod->getAvailability() < AR_Deprecated)
3371        List->setMethod(Method);
3372    }
3373
3374    return;
3375  }
3376
3377  // We have a new signature for an existing method - add it.
3378  // This is extremely rare. Only 1% of Cocoa selectors are "overloaded".
3379  ObjCMethodList *Mem = BumpAlloc.Allocate<ObjCMethodList>();
3380
3381  // We insert it right before ListWithSameDeclaration.
3382  if (ListWithSameDeclaration) {
3383    auto *List = new (Mem) ObjCMethodList(*ListWithSameDeclaration);
3384    // FIXME: should we clear the other bits in ListWithSameDeclaration?
3385    ListWithSameDeclaration->setMethod(Method);
3386    ListWithSameDeclaration->setNext(List);
3387    return;
3388  }
3389
3390  Previous->setNext(new (Mem) ObjCMethodList(Method));
3391}
3392
3393/// Read the contents of the method pool for a given selector from
3394/// external storage.
3395void Sema::ReadMethodPool(Selector Sel) {
3396  assert(ExternalSource && "We need an external AST source");
3397  ExternalSource->ReadMethodPool(Sel);
3398}
3399
3400void Sema::updateOutOfDateSelector(Selector Sel) {
3401  if (!ExternalSource)
3402    return;
3403  ExternalSource->updateOutOfDateSelector(Sel);
3404}
3405
3406void Sema::AddMethodToGlobalPool(ObjCMethodDecl *Method, bool impl,
3407                                 bool instance) {
3408  // Ignore methods of invalid containers.
3409  if (cast<Decl>(Method->getDeclContext())->isInvalidDecl())
3410    return;
3411
3412  if (ExternalSource)
3413    ReadMethodPool(Method->getSelector());
3414
3415  GlobalMethodPool::iterator Pos = MethodPool.find(Method->getSelector());
3416  if (Pos == MethodPool.end())
3417    Pos = MethodPool.insert(std::make_pair(Method->getSelector(),
3418                                           GlobalMethods())).first;
3419
3420  Method->setDefined(impl);
3421
3422  ObjCMethodList &Entry = instance ? Pos->second.first : Pos->second.second;
3423  addMethodToGlobalList(&Entry, Method);
3424}
3425
3426/// Determines if this is an "acceptable" loose mismatch in the global
3427/// method pool.  This exists mostly as a hack to get around certain
3428/// global mismatches which we can't afford to make warnings / errors.
3429/// Really, what we want is a way to take a method out of the global
3430/// method pool.
3431static bool isAcceptableMethodMismatch(ObjCMethodDecl *chosen,
3432                                       ObjCMethodDecl *other) {
3433  if (!chosen->isInstanceMethod())
3434    return false;
3435
3436  if (chosen->isDirectMethod() != other->isDirectMethod())
3437    return false;
3438
3439  Selector sel = chosen->getSelector();
3440  if (!sel.isUnarySelector() || sel.getNameForSlot(0) != "length")
3441    return false;
3442
3443  // Don't complain about mismatches for -length if the method we
3444  // chose has an integral result type.
3445  return (chosen->getReturnType()->isIntegerType());
3446}
3447
3448/// Return true if the given method is wthin the type bound.
3449static bool FilterMethodsByTypeBound(ObjCMethodDecl *Method,
3450                                     const ObjCObjectType *TypeBound) {
3451  if (!TypeBound)
3452    return true;
3453
3454  if (TypeBound->isObjCId())
3455    // FIXME: should we handle the case of bounding to id<A, B> differently?
3456    return true;
3457
3458  auto *BoundInterface = TypeBound->getInterface();
3459  assert(BoundInterface && "unexpected object type!");
3460
3461  // Check if the Method belongs to a protocol. We should allow any method
3462  // defined in any protocol, because any subclass could adopt the protocol.
3463  auto *MethodProtocol = dyn_cast<ObjCProtocolDecl>(Method->getDeclContext());
3464  if (MethodProtocol) {
3465    return true;
3466  }
3467
3468  // If the Method belongs to a class, check if it belongs to the class
3469  // hierarchy of the class bound.
3470  if (ObjCInterfaceDecl *MethodInterface = Method->getClassInterface()) {
3471    // We allow methods declared within classes that are part of the hierarchy
3472    // of the class bound (superclass of, subclass of, or the same as the class
3473    // bound).
3474    return MethodInterface == BoundInterface ||
3475           MethodInterface->isSuperClassOf(BoundInterface) ||
3476           BoundInterface->isSuperClassOf(MethodInterface);
3477  }
3478  llvm_unreachable("unknown method context");
3479}
3480
3481/// We first select the type of the method: Instance or Factory, then collect
3482/// all methods with that type.
3483bool Sema::CollectMultipleMethodsInGlobalPool(
3484    Selector Sel, SmallVectorImpl<ObjCMethodDecl *> &Methods,
3485    bool InstanceFirst, bool CheckTheOther,
3486    const ObjCObjectType *TypeBound) {
3487  if (ExternalSource)
3488    ReadMethodPool(Sel);
3489
3490  GlobalMethodPool::iterator Pos = MethodPool.find(Sel);
3491  if (Pos == MethodPool.end())
3492    return false;
3493
3494  // Gather the non-hidden methods.
3495  ObjCMethodList &MethList = InstanceFirst ? Pos->second.first :
3496                             Pos->second.second;
3497  for (ObjCMethodList *M = &MethList; M; M = M->getNext())
3498    if (M->getMethod() && !M->getMethod()->isHidden()) {
3499      if (FilterMethodsByTypeBound(M->getMethod(), TypeBound))
3500        Methods.push_back(M->getMethod());
3501    }
3502
3503  // Return if we find any method with the desired kind.
3504  if (!Methods.empty())
3505    return Methods.size() > 1;
3506
3507  if (!CheckTheOther)
3508    return false;
3509
3510  // Gather the other kind.
3511  ObjCMethodList &MethList2 = InstanceFirst ? Pos->second.second :
3512                              Pos->second.first;
3513  for (ObjCMethodList *M = &MethList2; M; M = M->getNext())
3514    if (M->getMethod() && !M->getMethod()->isHidden()) {
3515      if (FilterMethodsByTypeBound(M->getMethod(), TypeBound))
3516        Methods.push_back(M->getMethod());
3517    }
3518
3519  return Methods.size() > 1;
3520}
3521
3522bool Sema::AreMultipleMethodsInGlobalPool(
3523    Selector Sel, ObjCMethodDecl *BestMethod, SourceRange R,
3524    bool receiverIdOrClass, SmallVectorImpl<ObjCMethodDecl *> &Methods) {
3525  // Diagnose finding more than one method in global pool.
3526  SmallVector<ObjCMethodDecl *, 4> FilteredMethods;
3527  FilteredMethods.push_back(BestMethod);
3528
3529  for (auto *M : Methods)
3530    if (M != BestMethod && !M->hasAttr<UnavailableAttr>())
3531      FilteredMethods.push_back(M);
3532
3533  if (FilteredMethods.size() > 1)
3534    DiagnoseMultipleMethodInGlobalPool(FilteredMethods, Sel, R,
3535                                       receiverIdOrClass);
3536
3537  GlobalMethodPool::iterator Pos = MethodPool.find(Sel);
3538  // Test for no method in the pool which should not trigger any warning by
3539  // caller.
3540  if (Pos == MethodPool.end())
3541    return true;
3542  ObjCMethodList &MethList =
3543    BestMethod->isInstanceMethod() ? Pos->second.first : Pos->second.second;
3544  return MethList.hasMoreThanOneDecl();
3545}
3546
3547ObjCMethodDecl *Sema::LookupMethodInGlobalPool(Selector Sel, SourceRange R,
3548                                               bool receiverIdOrClass,
3549                                               bool instance) {
3550  if (ExternalSource)
3551    ReadMethodPool(Sel);
3552
3553  GlobalMethodPool::iterator Pos = MethodPool.find(Sel);
3554  if (Pos == MethodPool.end())
3555    return nullptr;
3556
3557  // Gather the non-hidden methods.
3558  ObjCMethodList &MethList = instance ? Pos->second.first : Pos->second.second;
3559  SmallVector<ObjCMethodDecl *, 4> Methods;
3560  for (ObjCMethodList *M = &MethList; M; M = M->getNext()) {
3561    if (M->getMethod() && !M->getMethod()->isHidden())
3562      return M->getMethod();
3563  }
3564  return nullptr;
3565}
3566
3567void Sema::DiagnoseMultipleMethodInGlobalPool(SmallVectorImpl<ObjCMethodDecl*> &Methods,
3568                                              Selector Sel, SourceRange R,
3569                                              bool receiverIdOrClass) {
3570  // We found multiple methods, so we may have to complain.
3571  bool issueDiagnostic = false, issueError = false;
3572
3573  // We support a warning which complains about *any* difference in
3574  // method signature.
3575  bool strictSelectorMatch =
3576  receiverIdOrClass &&
3577  !Diags.isIgnored(diag::warn_strict_multiple_method_decl, R.getBegin());
3578  if (strictSelectorMatch) {
3579    for (unsigned I = 1, N = Methods.size(); I != N; ++I) {
3580      if (!MatchTwoMethodDeclarations(Methods[0], Methods[I], MMS_strict)) {
3581        issueDiagnostic = true;
3582        break;
3583      }
3584    }
3585  }
3586
3587  // If we didn't see any strict differences, we won't see any loose
3588  // differences.  In ARC, however, we also need to check for loose
3589  // mismatches, because most of them are errors.
3590  if (!strictSelectorMatch ||
3591      (issueDiagnostic && getLangOpts().ObjCAutoRefCount))
3592    for (unsigned I = 1, N = Methods.size(); I != N; ++I) {
3593      // This checks if the methods differ in type mismatch.
3594      if (!MatchTwoMethodDeclarations(Methods[0], Methods[I], MMS_loose) &&
3595          !isAcceptableMethodMismatch(Methods[0], Methods[I])) {
3596        issueDiagnostic = true;
3597        if (getLangOpts().ObjCAutoRefCount)
3598          issueError = true;
3599        break;
3600      }
3601    }
3602
3603  if (issueDiagnostic) {
3604    if (issueError)
3605      Diag(R.getBegin(), diag::err_arc_multiple_method_decl) << Sel << R;
3606    else if (strictSelectorMatch)
3607      Diag(R.getBegin(), diag::warn_strict_multiple_method_decl) << Sel << R;
3608    else
3609      Diag(R.getBegin(), diag::warn_multiple_method_decl) << Sel << R;
3610
3611    Diag(Methods[0]->getBeginLoc(),
3612         issueError ? diag::note_possibility : diag::note_using)
3613        << Methods[0]->getSourceRange();
3614    for (unsigned I = 1, N = Methods.size(); I != N; ++I) {
3615      Diag(Methods[I]->getBeginLoc(), diag::note_also_found)
3616          << Methods[I]->getSourceRange();
3617    }
3618  }
3619}
3620
3621ObjCMethodDecl *Sema::LookupImplementedMethodInGlobalPool(Selector Sel) {
3622  GlobalMethodPool::iterator Pos = MethodPool.find(Sel);
3623  if (Pos == MethodPool.end())
3624    return nullptr;
3625
3626  GlobalMethods &Methods = Pos->second;
3627  for (const ObjCMethodList *Method = &Methods.first; Method;
3628       Method = Method->getNext())
3629    if (Method->getMethod() &&
3630        (Method->getMethod()->isDefined() ||
3631         Method->getMethod()->isPropertyAccessor()))
3632      return Method->getMethod();
3633
3634  for (const ObjCMethodList *Method = &Methods.second; Method;
3635       Method = Method->getNext())
3636    if (Method->getMethod() &&
3637        (Method->getMethod()->isDefined() ||
3638         Method->getMethod()->isPropertyAccessor()))
3639      return Method->getMethod();
3640  return nullptr;
3641}
3642
3643static void
3644HelperSelectorsForTypoCorrection(
3645                      SmallVectorImpl<const ObjCMethodDecl *> &BestMethod,
3646                      StringRef Typo, const ObjCMethodDecl * Method) {
3647  const unsigned MaxEditDistance = 1;
3648  unsigned BestEditDistance = MaxEditDistance + 1;
3649  std::string MethodName = Method->getSelector().getAsString();
3650
3651  unsigned MinPossibleEditDistance = abs((int)MethodName.size() - (int)Typo.size());
3652  if (MinPossibleEditDistance > 0 &&
3653      Typo.size() / MinPossibleEditDistance < 1)
3654    return;
3655  unsigned EditDistance = Typo.edit_distance(MethodName, true, MaxEditDistance);
3656  if (EditDistance > MaxEditDistance)
3657    return;
3658  if (EditDistance == BestEditDistance)
3659    BestMethod.push_back(Method);
3660  else if (EditDistance < BestEditDistance) {
3661    BestMethod.clear();
3662    BestMethod.push_back(Method);
3663  }
3664}
3665
3666static bool HelperIsMethodInObjCType(Sema &S, Selector Sel,
3667                                     QualType ObjectType) {
3668  if (ObjectType.isNull())
3669    return true;
3670  if (S.LookupMethodInObjectType(Sel, ObjectType, true/*Instance method*/))
3671    return true;
3672  return S.LookupMethodInObjectType(Sel, ObjectType, false/*Class method*/) !=
3673         nullptr;
3674}
3675
3676const ObjCMethodDecl *
3677Sema::SelectorsForTypoCorrection(Selector Sel,
3678                                 QualType ObjectType) {
3679  unsigned NumArgs = Sel.getNumArgs();
3680  SmallVector<const ObjCMethodDecl *, 8> Methods;
3681  bool ObjectIsId = true, ObjectIsClass = true;
3682  if (ObjectType.isNull())
3683    ObjectIsId = ObjectIsClass = false;
3684  else if (!ObjectType->isObjCObjectPointerType())
3685    return nullptr;
3686  else if (const ObjCObjectPointerType *ObjCPtr =
3687           ObjectType->getAsObjCInterfacePointerType()) {
3688    ObjectType = QualType(ObjCPtr->getInterfaceType(), 0);
3689    ObjectIsId = ObjectIsClass = false;
3690  }
3691  else if (ObjectType->isObjCIdType() || ObjectType->isObjCQualifiedIdType())
3692    ObjectIsClass = false;
3693  else if (ObjectType->isObjCClassType() || ObjectType->isObjCQualifiedClassType())
3694    ObjectIsId = false;
3695  else
3696    return nullptr;
3697
3698  for (GlobalMethodPool::iterator b = MethodPool.begin(),
3699       e = MethodPool.end(); b != e; b++) {
3700    // instance methods
3701    for (ObjCMethodList *M = &b->second.first; M; M=M->getNext())
3702      if (M->getMethod() &&
3703          (M->getMethod()->getSelector().getNumArgs() == NumArgs) &&
3704          (M->getMethod()->getSelector() != Sel)) {
3705        if (ObjectIsId)
3706          Methods.push_back(M->getMethod());
3707        else if (!ObjectIsClass &&
3708                 HelperIsMethodInObjCType(*this, M->getMethod()->getSelector(),
3709                                          ObjectType))
3710          Methods.push_back(M->getMethod());
3711      }
3712    // class methods
3713    for (ObjCMethodList *M = &b->second.second; M; M=M->getNext())
3714      if (M->getMethod() &&
3715          (M->getMethod()->getSelector().getNumArgs() == NumArgs) &&
3716          (M->getMethod()->getSelector() != Sel)) {
3717        if (ObjectIsClass)
3718          Methods.push_back(M->getMethod());
3719        else if (!ObjectIsId &&
3720                 HelperIsMethodInObjCType(*this, M->getMethod()->getSelector(),
3721                                          ObjectType))
3722          Methods.push_back(M->getMethod());
3723      }
3724  }
3725
3726  SmallVector<const ObjCMethodDecl *, 8> SelectedMethods;
3727  for (unsigned i = 0, e = Methods.size(); i < e; i++) {
3728    HelperSelectorsForTypoCorrection(SelectedMethods,
3729                                     Sel.getAsString(), Methods[i]);
3730  }
3731  return (SelectedMethods.size() == 1) ? SelectedMethods[0] : nullptr;
3732}
3733
3734/// DiagnoseDuplicateIvars -
3735/// Check for duplicate ivars in the entire class at the start of
3736/// \@implementation. This becomes necesssary because class extension can
3737/// add ivars to a class in random order which will not be known until
3738/// class's \@implementation is seen.
3739void Sema::DiagnoseDuplicateIvars(ObjCInterfaceDecl *ID,
3740                                  ObjCInterfaceDecl *SID) {
3741  for (auto *Ivar : ID->ivars()) {
3742    if (Ivar->isInvalidDecl())
3743      continue;
3744    if (IdentifierInfo *II = Ivar->getIdentifier()) {
3745      ObjCIvarDecl* prevIvar = SID->lookupInstanceVariable(II);
3746      if (prevIvar) {
3747        Diag(Ivar->getLocation(), diag::err_duplicate_member) << II;
3748        Diag(prevIvar->getLocation(), diag::note_previous_declaration);
3749        Ivar->setInvalidDecl();
3750      }
3751    }
3752  }
3753}
3754
3755/// Diagnose attempts to define ARC-__weak ivars when __weak is disabled.
3756static void DiagnoseWeakIvars(Sema &S, ObjCImplementationDecl *ID) {
3757  if (S.getLangOpts().ObjCWeak) return;
3758
3759  for (auto ivar = ID->getClassInterface()->all_declared_ivar_begin();
3760         ivar; ivar = ivar->getNextIvar()) {
3761    if (ivar->isInvalidDecl()) continue;
3762    if (ivar->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
3763      if (S.getLangOpts().ObjCWeakRuntime) {
3764        S.Diag(ivar->getLocation(), diag::err_arc_weak_disabled);
3765      } else {
3766        S.Diag(ivar->getLocation(), diag::err_arc_weak_no_runtime);
3767      }
3768    }
3769  }
3770}
3771
3772/// Diagnose attempts to use flexible array member with retainable object type.
3773static void DiagnoseRetainableFlexibleArrayMember(Sema &S,
3774                                                  ObjCInterfaceDecl *ID) {
3775  if (!S.getLangOpts().ObjCAutoRefCount)
3776    return;
3777
3778  for (auto ivar = ID->all_declared_ivar_begin(); ivar;
3779       ivar = ivar->getNextIvar()) {
3780    if (ivar->isInvalidDecl())
3781      continue;
3782    QualType IvarTy = ivar->getType();
3783    if (IvarTy->isIncompleteArrayType() &&
3784        (IvarTy.getObjCLifetime() != Qualifiers::OCL_ExplicitNone) &&
3785        IvarTy->isObjCLifetimeType()) {
3786      S.Diag(ivar->getLocation(), diag::err_flexible_array_arc_retainable);
3787      ivar->setInvalidDecl();
3788    }
3789  }
3790}
3791
3792Sema::ObjCContainerKind Sema::getObjCContainerKind() const {
3793  switch (CurContext->getDeclKind()) {
3794    case Decl::ObjCInterface:
3795      return Sema::OCK_Interface;
3796    case Decl::ObjCProtocol:
3797      return Sema::OCK_Protocol;
3798    case Decl::ObjCCategory:
3799      if (cast<ObjCCategoryDecl>(CurContext)->IsClassExtension())
3800        return Sema::OCK_ClassExtension;
3801      return Sema::OCK_Category;
3802    case Decl::ObjCImplementation:
3803      return Sema::OCK_Implementation;
3804    case Decl::ObjCCategoryImpl:
3805      return Sema::OCK_CategoryImplementation;
3806
3807    default:
3808      return Sema::OCK_None;
3809  }
3810}
3811
3812static bool IsVariableSizedType(QualType T) {
3813  if (T->isIncompleteArrayType())
3814    return true;
3815  const auto *RecordTy = T->getAs<RecordType>();
3816  return (RecordTy && RecordTy->getDecl()->hasFlexibleArrayMember());
3817}
3818
3819static void DiagnoseVariableSizedIvars(Sema &S, ObjCContainerDecl *OCD) {
3820  ObjCInterfaceDecl *IntfDecl = nullptr;
3821  ObjCInterfaceDecl::ivar_range Ivars = llvm::make_range(
3822      ObjCInterfaceDecl::ivar_iterator(), ObjCInterfaceDecl::ivar_iterator());
3823  if ((IntfDecl = dyn_cast<ObjCInterfaceDecl>(OCD))) {
3824    Ivars = IntfDecl->ivars();
3825  } else if (auto *ImplDecl = dyn_cast<ObjCImplementationDecl>(OCD)) {
3826    IntfDecl = ImplDecl->getClassInterface();
3827    Ivars = ImplDecl->ivars();
3828  } else if (auto *CategoryDecl = dyn_cast<ObjCCategoryDecl>(OCD)) {
3829    if (CategoryDecl->IsClassExtension()) {
3830      IntfDecl = CategoryDecl->getClassInterface();
3831      Ivars = CategoryDecl->ivars();
3832    }
3833  }
3834
3835  // Check if variable sized ivar is in interface and visible to subclasses.
3836  if (!isa<ObjCInterfaceDecl>(OCD)) {
3837    for (auto ivar : Ivars) {
3838      if (!ivar->isInvalidDecl() && IsVariableSizedType(ivar->getType())) {
3839        S.Diag(ivar->getLocation(), diag::warn_variable_sized_ivar_visibility)
3840            << ivar->getDeclName() << ivar->getType();
3841      }
3842    }
3843  }
3844
3845  // Subsequent checks require interface decl.
3846  if (!IntfDecl)
3847    return;
3848
3849  // Check if variable sized ivar is followed by another ivar.
3850  for (ObjCIvarDecl *ivar = IntfDecl->all_declared_ivar_begin(); ivar;
3851       ivar = ivar->getNextIvar()) {
3852    if (ivar->isInvalidDecl() || !ivar->getNextIvar())
3853      continue;
3854    QualType IvarTy = ivar->getType();
3855    bool IsInvalidIvar = false;
3856    if (IvarTy->isIncompleteArrayType()) {
3857      S.Diag(ivar->getLocation(), diag::err_flexible_array_not_at_end)
3858          << ivar->getDeclName() << IvarTy
3859          << TTK_Class; // Use "class" for Obj-C.
3860      IsInvalidIvar = true;
3861    } else if (const RecordType *RecordTy = IvarTy->getAs<RecordType>()) {
3862      if (RecordTy->getDecl()->hasFlexibleArrayMember()) {
3863        S.Diag(ivar->getLocation(),
3864               diag::err_objc_variable_sized_type_not_at_end)
3865            << ivar->getDeclName() << IvarTy;
3866        IsInvalidIvar = true;
3867      }
3868    }
3869    if (IsInvalidIvar) {
3870      S.Diag(ivar->getNextIvar()->getLocation(),
3871             diag::note_next_ivar_declaration)
3872          << ivar->getNextIvar()->getSynthesize();
3873      ivar->setInvalidDecl();
3874    }
3875  }
3876
3877  // Check if ObjC container adds ivars after variable sized ivar in superclass.
3878  // Perform the check only if OCD is the first container to declare ivars to
3879  // avoid multiple warnings for the same ivar.
3880  ObjCIvarDecl *FirstIvar =
3881      (Ivars.begin() == Ivars.end()) ? nullptr : *Ivars.begin();
3882  if (FirstIvar && (FirstIvar == IntfDecl->all_declared_ivar_begin())) {
3883    const ObjCInterfaceDecl *SuperClass = IntfDecl->getSuperClass();
3884    while (SuperClass && SuperClass->ivar_empty())
3885      SuperClass = SuperClass->getSuperClass();
3886    if (SuperClass) {
3887      auto IvarIter = SuperClass->ivar_begin();
3888      std::advance(IvarIter, SuperClass->ivar_size() - 1);
3889      const ObjCIvarDecl *LastIvar = *IvarIter;
3890      if (IsVariableSizedType(LastIvar->getType())) {
3891        S.Diag(FirstIvar->getLocation(),
3892               diag::warn_superclass_variable_sized_type_not_at_end)
3893            << FirstIvar->getDeclName() << LastIvar->getDeclName()
3894            << LastIvar->getType() << SuperClass->getDeclName();
3895        S.Diag(LastIvar->getLocation(), diag::note_entity_declared_at)
3896            << LastIvar->getDeclName();
3897      }
3898    }
3899  }
3900}
3901
3902// Note: For class/category implementations, allMethods is always null.
3903Decl *Sema::ActOnAtEnd(Scope *S, SourceRange AtEnd, ArrayRef<Decl *> allMethods,
3904                       ArrayRef<DeclGroupPtrTy> allTUVars) {
3905  if (getObjCContainerKind() == Sema::OCK_None)
3906    return nullptr;
3907
3908  assert(AtEnd.isValid() && "Invalid location for '@end'");
3909
3910  auto *OCD = cast<ObjCContainerDecl>(CurContext);
3911  Decl *ClassDecl = OCD;
3912
3913  bool isInterfaceDeclKind =
3914        isa<ObjCInterfaceDecl>(ClassDecl) || isa<ObjCCategoryDecl>(ClassDecl)
3915         || isa<ObjCProtocolDecl>(ClassDecl);
3916  bool checkIdenticalMethods = isa<ObjCImplementationDecl>(ClassDecl);
3917
3918  // Make synthesized accessor stub functions visible.
3919  // ActOnPropertyImplDecl() creates them as not visible in case
3920  // they are overridden by an explicit method that is encountered
3921  // later.
3922  if (auto *OID = dyn_cast<ObjCImplementationDecl>(CurContext)) {
3923    for (auto PropImpl : OID->property_impls()) {
3924      if (auto *Getter = PropImpl->getGetterMethodDecl())
3925        if (Getter->isSynthesizedAccessorStub()) {
3926          OID->makeDeclVisibleInContext(Getter);
3927          OID->addDecl(Getter);
3928        }
3929      if (auto *Setter = PropImpl->getSetterMethodDecl())
3930        if (Setter->isSynthesizedAccessorStub()) {
3931          OID->makeDeclVisibleInContext(Setter);
3932          OID->addDecl(Setter);
3933        }
3934    }
3935  }
3936
3937  // FIXME: Remove these and use the ObjCContainerDecl/DeclContext.
3938  llvm::DenseMap<Selector, const ObjCMethodDecl*> InsMap;
3939  llvm::DenseMap<Selector, const ObjCMethodDecl*> ClsMap;
3940
3941  for (unsigned i = 0, e = allMethods.size(); i != e; i++ ) {
3942    ObjCMethodDecl *Method =
3943      cast_or_null<ObjCMethodDecl>(allMethods[i]);
3944
3945    if (!Method) continue;  // Already issued a diagnostic.
3946    if (Method->isInstanceMethod()) {
3947      /// Check for instance method of the same name with incompatible types
3948      const ObjCMethodDecl *&PrevMethod = InsMap[Method->getSelector()];
3949      bool match = PrevMethod ? MatchTwoMethodDeclarations(Method, PrevMethod)
3950                              : false;
3951      if ((isInterfaceDeclKind && PrevMethod && !match)
3952          || (checkIdenticalMethods && match)) {
3953          Diag(Method->getLocation(), diag::err_duplicate_method_decl)
3954            << Method->getDeclName();
3955          Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
3956        Method->setInvalidDecl();
3957      } else {
3958        if (PrevMethod) {
3959          Method->setAsRedeclaration(PrevMethod);
3960          if (!Context.getSourceManager().isInSystemHeader(
3961                 Method->getLocation()))
3962            Diag(Method->getLocation(), diag::warn_duplicate_method_decl)
3963              << Method->getDeclName();
3964          Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
3965        }
3966        InsMap[Method->getSelector()] = Method;
3967        /// The following allows us to typecheck messages to "id".
3968        AddInstanceMethodToGlobalPool(Method);
3969      }
3970    } else {
3971      /// Check for class method of the same name with incompatible types
3972      const ObjCMethodDecl *&PrevMethod = ClsMap[Method->getSelector()];
3973      bool match = PrevMethod ? MatchTwoMethodDeclarations(Method, PrevMethod)
3974                              : false;
3975      if ((isInterfaceDeclKind && PrevMethod && !match)
3976          || (checkIdenticalMethods && match)) {
3977        Diag(Method->getLocation(), diag::err_duplicate_method_decl)
3978          << Method->getDeclName();
3979        Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
3980        Method->setInvalidDecl();
3981      } else {
3982        if (PrevMethod) {
3983          Method->setAsRedeclaration(PrevMethod);
3984          if (!Context.getSourceManager().isInSystemHeader(
3985                 Method->getLocation()))
3986            Diag(Method->getLocation(), diag::warn_duplicate_method_decl)
3987              << Method->getDeclName();
3988          Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
3989        }
3990        ClsMap[Method->getSelector()] = Method;
3991        AddFactoryMethodToGlobalPool(Method);
3992      }
3993    }
3994  }
3995  if (isa<ObjCInterfaceDecl>(ClassDecl)) {
3996    // Nothing to do here.
3997  } else if (ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(ClassDecl)) {
3998    // Categories are used to extend the class by declaring new methods.
3999    // By the same token, they are also used to add new properties. No
4000    // need to compare the added property to those in the class.
4001
4002    if (C->IsClassExtension()) {
4003      ObjCInterfaceDecl *CCPrimary = C->getClassInterface();
4004      DiagnoseClassExtensionDupMethods(C, CCPrimary);
4005    }
4006  }
4007  if (ObjCContainerDecl *CDecl = dyn_cast<ObjCContainerDecl>(ClassDecl)) {
4008    if (CDecl->getIdentifier())
4009      // ProcessPropertyDecl is responsible for diagnosing conflicts with any
4010      // user-defined setter/getter. It also synthesizes setter/getter methods
4011      // and adds them to the DeclContext and global method pools.
4012      for (auto *I : CDecl->properties())
4013        ProcessPropertyDecl(I);
4014    CDecl->setAtEndRange(AtEnd);
4015  }
4016  if (ObjCImplementationDecl *IC=dyn_cast<ObjCImplementationDecl>(ClassDecl)) {
4017    IC->setAtEndRange(AtEnd);
4018    if (ObjCInterfaceDecl* IDecl = IC->getClassInterface()) {
4019      // Any property declared in a class extension might have user
4020      // declared setter or getter in current class extension or one
4021      // of the other class extensions. Mark them as synthesized as
4022      // property will be synthesized when property with same name is
4023      // seen in the @implementation.
4024      for (const auto *Ext : IDecl->visible_extensions()) {
4025        for (const auto *Property : Ext->instance_properties()) {
4026          // Skip over properties declared @dynamic
4027          if (const ObjCPropertyImplDecl *PIDecl
4028              = IC->FindPropertyImplDecl(Property->getIdentifier(),
4029                                         Property->getQueryKind()))
4030            if (PIDecl->getPropertyImplementation()
4031                  == ObjCPropertyImplDecl::Dynamic)
4032              continue;
4033
4034          for (const auto *Ext : IDecl->visible_extensions()) {
4035            if (ObjCMethodDecl *GetterMethod =
4036                    Ext->getInstanceMethod(Property->getGetterName()))
4037              GetterMethod->setPropertyAccessor(true);
4038            if (!Property->isReadOnly())
4039              if (ObjCMethodDecl *SetterMethod
4040                    = Ext->getInstanceMethod(Property->getSetterName()))
4041                SetterMethod->setPropertyAccessor(true);
4042          }
4043        }
4044      }
4045      ImplMethodsVsClassMethods(S, IC, IDecl);
4046      AtomicPropertySetterGetterRules(IC, IDecl);
4047      DiagnoseOwningPropertyGetterSynthesis(IC);
4048      DiagnoseUnusedBackingIvarInAccessor(S, IC);
4049      if (IDecl->hasDesignatedInitializers())
4050        DiagnoseMissingDesignatedInitOverrides(IC, IDecl);
4051      DiagnoseWeakIvars(*this, IC);
4052      DiagnoseRetainableFlexibleArrayMember(*this, IDecl);
4053
4054      bool HasRootClassAttr = IDecl->hasAttr<ObjCRootClassAttr>();
4055      if (IDecl->getSuperClass() == nullptr) {
4056        // This class has no superclass, so check that it has been marked with
4057        // __attribute((objc_root_class)).
4058        if (!HasRootClassAttr) {
4059          SourceLocation DeclLoc(IDecl->getLocation());
4060          SourceLocation SuperClassLoc(getLocForEndOfToken(DeclLoc));
4061          Diag(DeclLoc, diag::warn_objc_root_class_missing)
4062            << IDecl->getIdentifier();
4063          // See if NSObject is in the current scope, and if it is, suggest
4064          // adding " : NSObject " to the class declaration.
4065          NamedDecl *IF = LookupSingleName(TUScope,
4066                                           NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject),
4067                                           DeclLoc, LookupOrdinaryName);
4068          ObjCInterfaceDecl *NSObjectDecl = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
4069          if (NSObjectDecl && NSObjectDecl->getDefinition()) {
4070            Diag(SuperClassLoc, diag::note_objc_needs_superclass)
4071              << FixItHint::CreateInsertion(SuperClassLoc, " : NSObject ");
4072          } else {
4073            Diag(SuperClassLoc, diag::note_objc_needs_superclass);
4074          }
4075        }
4076      } else if (HasRootClassAttr) {
4077        // Complain that only root classes may have this attribute.
4078        Diag(IDecl->getLocation(), diag::err_objc_root_class_subclass);
4079      }
4080
4081      if (const ObjCInterfaceDecl *Super = IDecl->getSuperClass()) {
4082        // An interface can subclass another interface with a
4083        // objc_subclassing_restricted attribute when it has that attribute as
4084        // well (because of interfaces imported from Swift). Therefore we have
4085        // to check if we can subclass in the implementation as well.
4086        if (IDecl->hasAttr<ObjCSubclassingRestrictedAttr>() &&
4087            Super->hasAttr<ObjCSubclassingRestrictedAttr>()) {
4088          Diag(IC->getLocation(), diag::err_restricted_superclass_mismatch);
4089          Diag(Super->getLocation(), diag::note_class_declared);
4090        }
4091      }
4092
4093      if (IDecl->hasAttr<ObjCClassStubAttr>())
4094        Diag(IC->getLocation(), diag::err_implementation_of_class_stub);
4095
4096      if (LangOpts.ObjCRuntime.isNonFragile()) {
4097        while (IDecl->getSuperClass()) {
4098          DiagnoseDuplicateIvars(IDecl, IDecl->getSuperClass());
4099          IDecl = IDecl->getSuperClass();
4100        }
4101      }
4102    }
4103    SetIvarInitializers(IC);
4104  } else if (ObjCCategoryImplDecl* CatImplClass =
4105                                   dyn_cast<ObjCCategoryImplDecl>(ClassDecl)) {
4106    CatImplClass->setAtEndRange(AtEnd);
4107
4108    // Find category interface decl and then check that all methods declared
4109    // in this interface are implemented in the category @implementation.
4110    if (ObjCInterfaceDecl* IDecl = CatImplClass->getClassInterface()) {
4111      if (ObjCCategoryDecl *Cat
4112            = IDecl->FindCategoryDeclaration(CatImplClass->getIdentifier())) {
4113        ImplMethodsVsClassMethods(S, CatImplClass, Cat);
4114      }
4115    }
4116  } else if (const auto *IntfDecl = dyn_cast<ObjCInterfaceDecl>(ClassDecl)) {
4117    if (const ObjCInterfaceDecl *Super = IntfDecl->getSuperClass()) {
4118      if (!IntfDecl->hasAttr<ObjCSubclassingRestrictedAttr>() &&
4119          Super->hasAttr<ObjCSubclassingRestrictedAttr>()) {
4120        Diag(IntfDecl->getLocation(), diag::err_restricted_superclass_mismatch);
4121        Diag(Super->getLocation(), diag::note_class_declared);
4122      }
4123    }
4124
4125    if (IntfDecl->hasAttr<ObjCClassStubAttr>() &&
4126        !IntfDecl->hasAttr<ObjCSubclassingRestrictedAttr>())
4127      Diag(IntfDecl->getLocation(), diag::err_class_stub_subclassing_mismatch);
4128  }
4129  DiagnoseVariableSizedIvars(*this, OCD);
4130  if (isInterfaceDeclKind) {
4131    // Reject invalid vardecls.
4132    for (unsigned i = 0, e = allTUVars.size(); i != e; i++) {
4133      DeclGroupRef DG = allTUVars[i].get();
4134      for (DeclGroupRef::iterator I = DG.begin(), E = DG.end(); I != E; ++I)
4135        if (VarDecl *VDecl = dyn_cast<VarDecl>(*I)) {
4136          if (!VDecl->hasExternalStorage())
4137            Diag(VDecl->getLocation(), diag::err_objc_var_decl_inclass);
4138        }
4139    }
4140  }
4141  ActOnObjCContainerFinishDefinition();
4142
4143  for (unsigned i = 0, e = allTUVars.size(); i != e; i++) {
4144    DeclGroupRef DG = allTUVars[i].get();
4145    for (DeclGroupRef::iterator I = DG.begin(), E = DG.end(); I != E; ++I)
4146      (*I)->setTopLevelDeclInObjCContainer();
4147    Consumer.HandleTopLevelDeclInObjCContainer(DG);
4148  }
4149
4150  ActOnDocumentableDecl(ClassDecl);
4151  return ClassDecl;
4152}
4153
4154/// CvtQTToAstBitMask - utility routine to produce an AST bitmask for
4155/// objective-c's type qualifier from the parser version of the same info.
4156static Decl::ObjCDeclQualifier
4157CvtQTToAstBitMask(ObjCDeclSpec::ObjCDeclQualifier PQTVal) {
4158  return (Decl::ObjCDeclQualifier) (unsigned) PQTVal;
4159}
4160
4161/// Check whether the declared result type of the given Objective-C
4162/// method declaration is compatible with the method's class.
4163///
4164static Sema::ResultTypeCompatibilityKind
4165CheckRelatedResultTypeCompatibility(Sema &S, ObjCMethodDecl *Method,
4166                                    ObjCInterfaceDecl *CurrentClass) {
4167  QualType ResultType = Method->getReturnType();
4168
4169  // If an Objective-C method inherits its related result type, then its
4170  // declared result type must be compatible with its own class type. The
4171  // declared result type is compatible if:
4172  if (const ObjCObjectPointerType *ResultObjectType
4173                                = ResultType->getAs<ObjCObjectPointerType>()) {
4174    //   - it is id or qualified id, or
4175    if (ResultObjectType->isObjCIdType() ||
4176        ResultObjectType->isObjCQualifiedIdType())
4177      return Sema::RTC_Compatible;
4178
4179    if (CurrentClass) {
4180      if (ObjCInterfaceDecl *ResultClass
4181                                      = ResultObjectType->getInterfaceDecl()) {
4182        //   - it is the same as the method's class type, or
4183        if (declaresSameEntity(CurrentClass, ResultClass))
4184          return Sema::RTC_Compatible;
4185
4186        //   - it is a superclass of the method's class type
4187        if (ResultClass->isSuperClassOf(CurrentClass))
4188          return Sema::RTC_Compatible;
4189      }
4190    } else {
4191      // Any Objective-C pointer type might be acceptable for a protocol
4192      // method; we just don't know.
4193      return Sema::RTC_Unknown;
4194    }
4195  }
4196
4197  return Sema::RTC_Incompatible;
4198}
4199
4200namespace {
4201/// A helper class for searching for methods which a particular method
4202/// overrides.
4203class OverrideSearch {
4204public:
4205  const ObjCMethodDecl *Method;
4206  llvm::SmallSetVector<ObjCMethodDecl*, 4> Overridden;
4207  bool Recursive;
4208
4209public:
4210  OverrideSearch(Sema &S, const ObjCMethodDecl *method) : Method(method) {
4211    Selector selector = method->getSelector();
4212
4213    // Bypass this search if we've never seen an instance/class method
4214    // with this selector before.
4215    Sema::GlobalMethodPool::iterator it = S.MethodPool.find(selector);
4216    if (it == S.MethodPool.end()) {
4217      if (!S.getExternalSource()) return;
4218      S.ReadMethodPool(selector);
4219
4220      it = S.MethodPool.find(selector);
4221      if (it == S.MethodPool.end())
4222        return;
4223    }
4224    const ObjCMethodList &list =
4225      method->isInstanceMethod() ? it->second.first : it->second.second;
4226    if (!list.getMethod()) return;
4227
4228    const ObjCContainerDecl *container
4229      = cast<ObjCContainerDecl>(method->getDeclContext());
4230
4231    // Prevent the search from reaching this container again.  This is
4232    // important with categories, which override methods from the
4233    // interface and each other.
4234    if (const ObjCCategoryDecl *Category =
4235            dyn_cast<ObjCCategoryDecl>(container)) {
4236      searchFromContainer(container);
4237      if (const ObjCInterfaceDecl *Interface = Category->getClassInterface())
4238        searchFromContainer(Interface);
4239    } else {
4240      searchFromContainer(container);
4241    }
4242  }
4243
4244  typedef decltype(Overridden)::iterator iterator;
4245  iterator begin() const { return Overridden.begin(); }
4246  iterator end() const { return Overridden.end(); }
4247
4248private:
4249  void searchFromContainer(const ObjCContainerDecl *container) {
4250    if (container->isInvalidDecl()) return;
4251
4252    switch (container->getDeclKind()) {
4253#define OBJCCONTAINER(type, base) \
4254    case Decl::type: \
4255      searchFrom(cast<type##Decl>(container)); \
4256      break;
4257#define ABSTRACT_DECL(expansion)
4258#define DECL(type, base) \
4259    case Decl::type:
4260#include "clang/AST/DeclNodes.inc"
4261      llvm_unreachable("not an ObjC container!");
4262    }
4263  }
4264
4265  void searchFrom(const ObjCProtocolDecl *protocol) {
4266    if (!protocol->hasDefinition())
4267      return;
4268
4269    // A method in a protocol declaration overrides declarations from
4270    // referenced ("parent") protocols.
4271    search(protocol->getReferencedProtocols());
4272  }
4273
4274  void searchFrom(const ObjCCategoryDecl *category) {
4275    // A method in a category declaration overrides declarations from
4276    // the main class and from protocols the category references.
4277    // The main class is handled in the constructor.
4278    search(category->getReferencedProtocols());
4279  }
4280
4281  void searchFrom(const ObjCCategoryImplDecl *impl) {
4282    // A method in a category definition that has a category
4283    // declaration overrides declarations from the category
4284    // declaration.
4285    if (ObjCCategoryDecl *category = impl->getCategoryDecl()) {
4286      search(category);
4287      if (ObjCInterfaceDecl *Interface = category->getClassInterface())
4288        search(Interface);
4289
4290    // Otherwise it overrides declarations from the class.
4291    } else if (const auto *Interface = impl->getClassInterface()) {
4292      search(Interface);
4293    }
4294  }
4295
4296  void searchFrom(const ObjCInterfaceDecl *iface) {
4297    // A method in a class declaration overrides declarations from
4298    if (!iface->hasDefinition())
4299      return;
4300
4301    //   - categories,
4302    for (auto *Cat : iface->known_categories())
4303      search(Cat);
4304
4305    //   - the super class, and
4306    if (ObjCInterfaceDecl *super = iface->getSuperClass())
4307      search(super);
4308
4309    //   - any referenced protocols.
4310    search(iface->getReferencedProtocols());
4311  }
4312
4313  void searchFrom(const ObjCImplementationDecl *impl) {
4314    // A method in a class implementation overrides declarations from
4315    // the class interface.
4316    if (const auto *Interface = impl->getClassInterface())
4317      search(Interface);
4318  }
4319
4320  void search(const ObjCProtocolList &protocols) {
4321    for (const auto *Proto : protocols)
4322      search(Proto);
4323  }
4324
4325  void search(const ObjCContainerDecl *container) {
4326    // Check for a method in this container which matches this selector.
4327    ObjCMethodDecl *meth = container->getMethod(Method->getSelector(),
4328                                                Method->isInstanceMethod(),
4329                                                /*AllowHidden=*/true);
4330
4331    // If we find one, record it and bail out.
4332    if (meth) {
4333      Overridden.insert(meth);
4334      return;
4335    }
4336
4337    // Otherwise, search for methods that a hypothetical method here
4338    // would have overridden.
4339
4340    // Note that we're now in a recursive case.
4341    Recursive = true;
4342
4343    searchFromContainer(container);
4344  }
4345};
4346} // end anonymous namespace
4347
4348void Sema::CheckObjCMethodDirectOverrides(ObjCMethodDecl *method,
4349                                          ObjCMethodDecl *overridden) {
4350  if (const auto *attr = overridden->getAttr<ObjCDirectAttr>()) {
4351    Diag(method->getLocation(), diag::err_objc_override_direct_method);
4352    Diag(attr->getLocation(), diag::note_previous_declaration);
4353  } else if (const auto *attr = method->getAttr<ObjCDirectAttr>()) {
4354    Diag(attr->getLocation(), diag::err_objc_direct_on_override)
4355        << isa<ObjCProtocolDecl>(overridden->getDeclContext());
4356    Diag(overridden->getLocation(), diag::note_previous_declaration);
4357  }
4358}
4359
4360void Sema::CheckObjCMethodOverrides(ObjCMethodDecl *ObjCMethod,
4361                                    ObjCInterfaceDecl *CurrentClass,
4362                                    ResultTypeCompatibilityKind RTC) {
4363  if (!ObjCMethod)
4364    return;
4365  // Search for overridden methods and merge information down from them.
4366  OverrideSearch overrides(*this, ObjCMethod);
4367  // Keep track if the method overrides any method in the class's base classes,
4368  // its protocols, or its categories' protocols; we will keep that info
4369  // in the ObjCMethodDecl.
4370  // For this info, a method in an implementation is not considered as
4371  // overriding the same method in the interface or its categories.
4372  bool hasOverriddenMethodsInBaseOrProtocol = false;
4373  for (ObjCMethodDecl *overridden : overrides) {
4374    if (!hasOverriddenMethodsInBaseOrProtocol) {
4375      if (isa<ObjCProtocolDecl>(overridden->getDeclContext()) ||
4376          CurrentClass != overridden->getClassInterface() ||
4377          overridden->isOverriding()) {
4378        CheckObjCMethodDirectOverrides(ObjCMethod, overridden);
4379        hasOverriddenMethodsInBaseOrProtocol = true;
4380      } else if (isa<ObjCImplDecl>(ObjCMethod->getDeclContext())) {
4381        // OverrideSearch will return as "overridden" the same method in the
4382        // interface. For hasOverriddenMethodsInBaseOrProtocol, we need to
4383        // check whether a category of a base class introduced a method with the
4384        // same selector, after the interface method declaration.
4385        // To avoid unnecessary lookups in the majority of cases, we use the
4386        // extra info bits in GlobalMethodPool to check whether there were any
4387        // category methods with this selector.
4388        GlobalMethodPool::iterator It =
4389            MethodPool.find(ObjCMethod->getSelector());
4390        if (It != MethodPool.end()) {
4391          ObjCMethodList &List =
4392            ObjCMethod->isInstanceMethod()? It->second.first: It->second.second;
4393          unsigned CategCount = List.getBits();
4394          if (CategCount > 0) {
4395            // If the method is in a category we'll do lookup if there were at
4396            // least 2 category methods recorded, otherwise only one will do.
4397            if (CategCount > 1 ||
4398                !isa<ObjCCategoryImplDecl>(overridden->getDeclContext())) {
4399              OverrideSearch overrides(*this, overridden);
4400              for (ObjCMethodDecl *SuperOverridden : overrides) {
4401                if (isa<ObjCProtocolDecl>(SuperOverridden->getDeclContext()) ||
4402                    CurrentClass != SuperOverridden->getClassInterface()) {
4403                  CheckObjCMethodDirectOverrides(ObjCMethod, SuperOverridden);
4404                  hasOverriddenMethodsInBaseOrProtocol = true;
4405                  overridden->setOverriding(true);
4406                  break;
4407                }
4408              }
4409            }
4410          }
4411        }
4412      }
4413    }
4414
4415    // Propagate down the 'related result type' bit from overridden methods.
4416    if (RTC != Sema::RTC_Incompatible && overridden->hasRelatedResultType())
4417      ObjCMethod->setRelatedResultType();
4418
4419    // Then merge the declarations.
4420    mergeObjCMethodDecls(ObjCMethod, overridden);
4421
4422    if (ObjCMethod->isImplicit() && overridden->isImplicit())
4423      continue; // Conflicting properties are detected elsewhere.
4424
4425    // Check for overriding methods
4426    if (isa<ObjCInterfaceDecl>(ObjCMethod->getDeclContext()) ||
4427        isa<ObjCImplementationDecl>(ObjCMethod->getDeclContext()))
4428      CheckConflictingOverridingMethod(ObjCMethod, overridden,
4429              isa<ObjCProtocolDecl>(overridden->getDeclContext()));
4430
4431    if (CurrentClass && overridden->getDeclContext() != CurrentClass &&
4432        isa<ObjCInterfaceDecl>(overridden->getDeclContext()) &&
4433        !overridden->isImplicit() /* not meant for properties */) {
4434      ObjCMethodDecl::param_iterator ParamI = ObjCMethod->param_begin(),
4435                                          E = ObjCMethod->param_end();
4436      ObjCMethodDecl::param_iterator PrevI = overridden->param_begin(),
4437                                     PrevE = overridden->param_end();
4438      for (; ParamI != E && PrevI != PrevE; ++ParamI, ++PrevI) {
4439        assert(PrevI != overridden->param_end() && "Param mismatch");
4440        QualType T1 = Context.getCanonicalType((*ParamI)->getType());
4441        QualType T2 = Context.getCanonicalType((*PrevI)->getType());
4442        // If type of argument of method in this class does not match its
4443        // respective argument type in the super class method, issue warning;
4444        if (!Context.typesAreCompatible(T1, T2)) {
4445          Diag((*ParamI)->getLocation(), diag::ext_typecheck_base_super)
4446            << T1 << T2;
4447          Diag(overridden->getLocation(), diag::note_previous_declaration);
4448          break;
4449        }
4450      }
4451    }
4452  }
4453
4454  ObjCMethod->setOverriding(hasOverriddenMethodsInBaseOrProtocol);
4455}
4456
4457/// Merge type nullability from for a redeclaration of the same entity,
4458/// producing the updated type of the redeclared entity.
4459static QualType mergeTypeNullabilityForRedecl(Sema &S, SourceLocation loc,
4460                                              QualType type,
4461                                              bool usesCSKeyword,
4462                                              SourceLocation prevLoc,
4463                                              QualType prevType,
4464                                              bool prevUsesCSKeyword) {
4465  // Determine the nullability of both types.
4466  auto nullability = type->getNullability(S.Context);
4467  auto prevNullability = prevType->getNullability(S.Context);
4468
4469  // Easy case: both have nullability.
4470  if (nullability.hasValue() == prevNullability.hasValue()) {
4471    // Neither has nullability; continue.
4472    if (!nullability)
4473      return type;
4474
4475    // The nullabilities are equivalent; do nothing.
4476    if (*nullability == *prevNullability)
4477      return type;
4478
4479    // Complain about mismatched nullability.
4480    S.Diag(loc, diag::err_nullability_conflicting)
4481      << DiagNullabilityKind(*nullability, usesCSKeyword)
4482      << DiagNullabilityKind(*prevNullability, prevUsesCSKeyword);
4483    return type;
4484  }
4485
4486  // If it's the redeclaration that has nullability, don't change anything.
4487  if (nullability)
4488    return type;
4489
4490  // Otherwise, provide the result with the same nullability.
4491  return S.Context.getAttributedType(
4492           AttributedType::getNullabilityAttrKind(*prevNullability),
4493           type, type);
4494}
4495
4496/// Merge information from the declaration of a method in the \@interface
4497/// (or a category/extension) into the corresponding method in the
4498/// @implementation (for a class or category).
4499static void mergeInterfaceMethodToImpl(Sema &S,
4500                                       ObjCMethodDecl *method,
4501                                       ObjCMethodDecl *prevMethod) {
4502  // Merge the objc_requires_super attribute.
4503  if (prevMethod->hasAttr<ObjCRequiresSuperAttr>() &&
4504      !method->hasAttr<ObjCRequiresSuperAttr>()) {
4505    // merge the attribute into implementation.
4506    method->addAttr(
4507      ObjCRequiresSuperAttr::CreateImplicit(S.Context,
4508                                            method->getLocation()));
4509  }
4510
4511  // Merge nullability of the result type.
4512  QualType newReturnType
4513    = mergeTypeNullabilityForRedecl(
4514        S, method->getReturnTypeSourceRange().getBegin(),
4515        method->getReturnType(),
4516        method->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability,
4517        prevMethod->getReturnTypeSourceRange().getBegin(),
4518        prevMethod->getReturnType(),
4519        prevMethod->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability);
4520  method->setReturnType(newReturnType);
4521
4522  // Handle each of the parameters.
4523  unsigned numParams = method->param_size();
4524  unsigned numPrevParams = prevMethod->param_size();
4525  for (unsigned i = 0, n = std::min(numParams, numPrevParams); i != n; ++i) {
4526    ParmVarDecl *param = method->param_begin()[i];
4527    ParmVarDecl *prevParam = prevMethod->param_begin()[i];
4528
4529    // Merge nullability.
4530    QualType newParamType
4531      = mergeTypeNullabilityForRedecl(
4532          S, param->getLocation(), param->getType(),
4533          param->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability,
4534          prevParam->getLocation(), prevParam->getType(),
4535          prevParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability);
4536    param->setType(newParamType);
4537  }
4538}
4539
4540/// Verify that the method parameters/return value have types that are supported
4541/// by the x86 target.
4542static void checkObjCMethodX86VectorTypes(Sema &SemaRef,
4543                                          const ObjCMethodDecl *Method) {
4544  assert(SemaRef.getASTContext().getTargetInfo().getTriple().getArch() ==
4545             llvm::Triple::x86 &&
4546         "x86-specific check invoked for a different target");
4547  SourceLocation Loc;
4548  QualType T;
4549  for (const ParmVarDecl *P : Method->parameters()) {
4550    if (P->getType()->isVectorType()) {
4551      Loc = P->getBeginLoc();
4552      T = P->getType();
4553      break;
4554    }
4555  }
4556  if (Loc.isInvalid()) {
4557    if (Method->getReturnType()->isVectorType()) {
4558      Loc = Method->getReturnTypeSourceRange().getBegin();
4559      T = Method->getReturnType();
4560    } else
4561      return;
4562  }
4563
4564  // Vector parameters/return values are not supported by objc_msgSend on x86 in
4565  // iOS < 9 and macOS < 10.11.
4566  const auto &Triple = SemaRef.getASTContext().getTargetInfo().getTriple();
4567  VersionTuple AcceptedInVersion;
4568  if (Triple.getOS() == llvm::Triple::IOS)
4569    AcceptedInVersion = VersionTuple(/*Major=*/9);
4570  else if (Triple.isMacOSX())
4571    AcceptedInVersion = VersionTuple(/*Major=*/10, /*Minor=*/11);
4572  else
4573    return;
4574  if (SemaRef.getASTContext().getTargetInfo().getPlatformMinVersion() >=
4575      AcceptedInVersion)
4576    return;
4577  SemaRef.Diag(Loc, diag::err_objc_method_unsupported_param_ret_type)
4578      << T << (Method->getReturnType()->isVectorType() ? /*return value*/ 1
4579                                                       : /*parameter*/ 0)
4580      << (Triple.isMacOSX() ? "macOS 10.11" : "iOS 9");
4581}
4582
4583Decl *Sema::ActOnMethodDeclaration(
4584    Scope *S, SourceLocation MethodLoc, SourceLocation EndLoc,
4585    tok::TokenKind MethodType, ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
4586    ArrayRef<SourceLocation> SelectorLocs, Selector Sel,
4587    // optional arguments. The number of types/arguments is obtained
4588    // from the Sel.getNumArgs().
4589    ObjCArgInfo *ArgInfo, DeclaratorChunk::ParamInfo *CParamInfo,
4590    unsigned CNumArgs, // c-style args
4591    const ParsedAttributesView &AttrList, tok::ObjCKeywordKind MethodDeclKind,
4592    bool isVariadic, bool MethodDefinition) {
4593  // Make sure we can establish a context for the method.
4594  if (!CurContext->isObjCContainer()) {
4595    Diag(MethodLoc, diag::err_missing_method_context);
4596    return nullptr;
4597  }
4598
4599  Decl *ClassDecl = cast<ObjCContainerDecl>(CurContext);
4600  QualType resultDeclType;
4601
4602  bool HasRelatedResultType = false;
4603  TypeSourceInfo *ReturnTInfo = nullptr;
4604  if (ReturnType) {
4605    resultDeclType = GetTypeFromParser(ReturnType, &ReturnTInfo);
4606
4607    if (CheckFunctionReturnType(resultDeclType, MethodLoc))
4608      return nullptr;
4609
4610    QualType bareResultType = resultDeclType;
4611    (void)AttributedType::stripOuterNullability(bareResultType);
4612    HasRelatedResultType = (bareResultType == Context.getObjCInstanceType());
4613  } else { // get the type for "id".
4614    resultDeclType = Context.getObjCIdType();
4615    Diag(MethodLoc, diag::warn_missing_method_return_type)
4616      << FixItHint::CreateInsertion(SelectorLocs.front(), "(id)");
4617  }
4618
4619  ObjCMethodDecl *ObjCMethod = ObjCMethodDecl::Create(
4620      Context, MethodLoc, EndLoc, Sel, resultDeclType, ReturnTInfo, CurContext,
4621      MethodType == tok::minus, isVariadic,
4622      /*isPropertyAccessor=*/false, /*isSynthesizedAccessorStub=*/false,
4623      /*isImplicitlyDeclared=*/false, /*isDefined=*/false,
4624      MethodDeclKind == tok::objc_optional ? ObjCMethodDecl::Optional
4625                                           : ObjCMethodDecl::Required,
4626      HasRelatedResultType);
4627
4628  SmallVector<ParmVarDecl*, 16> Params;
4629
4630  for (unsigned i = 0, e = Sel.getNumArgs(); i != e; ++i) {
4631    QualType ArgType;
4632    TypeSourceInfo *DI;
4633
4634    if (!ArgInfo[i].Type) {
4635      ArgType = Context.getObjCIdType();
4636      DI = nullptr;
4637    } else {
4638      ArgType = GetTypeFromParser(ArgInfo[i].Type, &DI);
4639    }
4640
4641    LookupResult R(*this, ArgInfo[i].Name, ArgInfo[i].NameLoc,
4642                   LookupOrdinaryName, forRedeclarationInCurContext());
4643    LookupName(R, S);
4644    if (R.isSingleResult()) {
4645      NamedDecl *PrevDecl = R.getFoundDecl();
4646      if (S->isDeclScope(PrevDecl)) {
4647        Diag(ArgInfo[i].NameLoc,
4648             (MethodDefinition ? diag::warn_method_param_redefinition
4649                               : diag::warn_method_param_declaration))
4650          << ArgInfo[i].Name;
4651        Diag(PrevDecl->getLocation(),
4652             diag::note_previous_declaration);
4653      }
4654    }
4655
4656    SourceLocation StartLoc = DI
4657      ? DI->getTypeLoc().getBeginLoc()
4658      : ArgInfo[i].NameLoc;
4659
4660    ParmVarDecl* Param = CheckParameter(ObjCMethod, StartLoc,
4661                                        ArgInfo[i].NameLoc, ArgInfo[i].Name,
4662                                        ArgType, DI, SC_None);
4663
4664    Param->setObjCMethodScopeInfo(i);
4665
4666    Param->setObjCDeclQualifier(
4667      CvtQTToAstBitMask(ArgInfo[i].DeclSpec.getObjCDeclQualifier()));
4668
4669    // Apply the attributes to the parameter.
4670    ProcessDeclAttributeList(TUScope, Param, ArgInfo[i].ArgAttrs);
4671    AddPragmaAttributes(TUScope, Param);
4672
4673    if (Param->hasAttr<BlocksAttr>()) {
4674      Diag(Param->getLocation(), diag::err_block_on_nonlocal);
4675      Param->setInvalidDecl();
4676    }
4677    S->AddDecl(Param);
4678    IdResolver.AddDecl(Param);
4679
4680    Params.push_back(Param);
4681  }
4682
4683  for (unsigned i = 0, e = CNumArgs; i != e; ++i) {
4684    ParmVarDecl *Param = cast<ParmVarDecl>(CParamInfo[i].Param);
4685    QualType ArgType = Param->getType();
4686    if (ArgType.isNull())
4687      ArgType = Context.getObjCIdType();
4688    else
4689      // Perform the default array/function conversions (C99 6.7.5.3p[7,8]).
4690      ArgType = Context.getAdjustedParameterType(ArgType);
4691
4692    Param->setDeclContext(ObjCMethod);
4693    Params.push_back(Param);
4694  }
4695
4696  ObjCMethod->setMethodParams(Context, Params, SelectorLocs);
4697  ObjCMethod->setObjCDeclQualifier(
4698    CvtQTToAstBitMask(ReturnQT.getObjCDeclQualifier()));
4699
4700  ProcessDeclAttributeList(TUScope, ObjCMethod, AttrList);
4701  AddPragmaAttributes(TUScope, ObjCMethod);
4702
4703  // Add the method now.
4704  const ObjCMethodDecl *PrevMethod = nullptr;
4705  if (ObjCImplDecl *ImpDecl = dyn_cast<ObjCImplDecl>(ClassDecl)) {
4706    if (MethodType == tok::minus) {
4707      PrevMethod = ImpDecl->getInstanceMethod(Sel);
4708      ImpDecl->addInstanceMethod(ObjCMethod);
4709    } else {
4710      PrevMethod = ImpDecl->getClassMethod(Sel);
4711      ImpDecl->addClassMethod(ObjCMethod);
4712    }
4713
4714    // If this method overrides a previous @synthesize declaration,
4715    // register it with the property.  Linear search through all
4716    // properties here, because the autosynthesized stub hasn't been
4717    // made visible yet, so it can be overriden by a later
4718    // user-specified implementation.
4719    for (ObjCPropertyImplDecl *PropertyImpl : ImpDecl->property_impls()) {
4720      if (auto *Setter = PropertyImpl->getSetterMethodDecl())
4721        if (Setter->getSelector() == Sel &&
4722            Setter->isInstanceMethod() == ObjCMethod->isInstanceMethod()) {
4723          assert(Setter->isSynthesizedAccessorStub() && "autosynth stub expected");
4724          PropertyImpl->setSetterMethodDecl(ObjCMethod);
4725        }
4726      if (auto *Getter = PropertyImpl->getGetterMethodDecl())
4727        if (Getter->getSelector() == Sel &&
4728            Getter->isInstanceMethod() == ObjCMethod->isInstanceMethod()) {
4729          assert(Getter->isSynthesizedAccessorStub() && "autosynth stub expected");
4730          PropertyImpl->setGetterMethodDecl(ObjCMethod);
4731          break;
4732        }
4733    }
4734
4735    // A method is either tagged direct explicitly, or inherits it from its
4736    // canonical declaration.
4737    //
4738    // We have to do the merge upfront and not in mergeInterfaceMethodToImpl()
4739    // because IDecl->lookupMethod() returns more possible matches than just
4740    // the canonical declaration.
4741    if (!ObjCMethod->isDirectMethod()) {
4742      const ObjCMethodDecl *CanonicalMD = ObjCMethod->getCanonicalDecl();
4743      if (const auto *attr = CanonicalMD->getAttr<ObjCDirectAttr>()) {
4744        ObjCMethod->addAttr(
4745            ObjCDirectAttr::CreateImplicit(Context, attr->getLocation()));
4746      }
4747    }
4748
4749    // Merge information from the @interface declaration into the
4750    // @implementation.
4751    if (ObjCInterfaceDecl *IDecl = ImpDecl->getClassInterface()) {
4752      if (auto *IMD = IDecl->lookupMethod(ObjCMethod->getSelector(),
4753                                          ObjCMethod->isInstanceMethod())) {
4754        mergeInterfaceMethodToImpl(*this, ObjCMethod, IMD);
4755
4756        // The Idecl->lookupMethod() above will find declarations for ObjCMethod
4757        // in one of these places:
4758        //
4759        // (1) the canonical declaration in an @interface container paired
4760        //     with the ImplDecl,
4761        // (2) non canonical declarations in @interface not paired with the
4762        //     ImplDecl for the same Class,
4763        // (3) any superclass container.
4764        //
4765        // Direct methods only allow for canonical declarations in the matching
4766        // container (case 1).
4767        //
4768        // Direct methods overriding a superclass declaration (case 3) is
4769        // handled during overrides checks in CheckObjCMethodOverrides().
4770        //
4771        // We deal with same-class container mismatches (Case 2) here.
4772        if (IDecl == IMD->getClassInterface()) {
4773          auto diagContainerMismatch = [&] {
4774            int decl = 0, impl = 0;
4775
4776            if (auto *Cat = dyn_cast<ObjCCategoryDecl>(IMD->getDeclContext()))
4777              decl = Cat->IsClassExtension() ? 1 : 2;
4778
4779            if (isa<ObjCCategoryImplDecl>(ImpDecl))
4780              impl = 1 + (decl != 0);
4781
4782            Diag(ObjCMethod->getLocation(),
4783                 diag::err_objc_direct_impl_decl_mismatch)
4784                << decl << impl;
4785            Diag(IMD->getLocation(), diag::note_previous_declaration);
4786          };
4787
4788          if (const auto *attr = ObjCMethod->getAttr<ObjCDirectAttr>()) {
4789            if (ObjCMethod->getCanonicalDecl() != IMD) {
4790              diagContainerMismatch();
4791            } else if (!IMD->isDirectMethod()) {
4792              Diag(attr->getLocation(), diag::err_objc_direct_missing_on_decl);
4793              Diag(IMD->getLocation(), diag::note_previous_declaration);
4794            }
4795          } else if (const auto *attr = IMD->getAttr<ObjCDirectAttr>()) {
4796            if (ObjCMethod->getCanonicalDecl() != IMD) {
4797              diagContainerMismatch();
4798            } else {
4799              ObjCMethod->addAttr(
4800                  ObjCDirectAttr::CreateImplicit(Context, attr->getLocation()));
4801            }
4802          }
4803        }
4804
4805        // Warn about defining -dealloc in a category.
4806        if (isa<ObjCCategoryImplDecl>(ImpDecl) && IMD->isOverriding() &&
4807            ObjCMethod->getSelector().getMethodFamily() == OMF_dealloc) {
4808          Diag(ObjCMethod->getLocation(), diag::warn_dealloc_in_category)
4809            << ObjCMethod->getDeclName();
4810        }
4811      } else if (ImpDecl->hasAttr<ObjCDirectMembersAttr>()) {
4812        ObjCMethod->addAttr(
4813            ObjCDirectAttr::CreateImplicit(Context, ObjCMethod->getLocation()));
4814      }
4815
4816      // Warn if a method declared in a protocol to which a category or
4817      // extension conforms is non-escaping and the implementation's method is
4818      // escaping.
4819      for (auto *C : IDecl->visible_categories())
4820        for (auto &P : C->protocols())
4821          if (auto *IMD = P->lookupMethod(ObjCMethod->getSelector(),
4822                                          ObjCMethod->isInstanceMethod())) {
4823            assert(ObjCMethod->parameters().size() ==
4824                       IMD->parameters().size() &&
4825                   "Methods have different number of parameters");
4826            auto OI = IMD->param_begin(), OE = IMD->param_end();
4827            auto NI = ObjCMethod->param_begin();
4828            for (; OI != OE; ++OI, ++NI)
4829              diagnoseNoescape(*NI, *OI, C, P, *this);
4830          }
4831    }
4832  } else {
4833    if (!isa<ObjCProtocolDecl>(ClassDecl)) {
4834      if (!ObjCMethod->isDirectMethod() &&
4835          ClassDecl->hasAttr<ObjCDirectMembersAttr>()) {
4836        ObjCMethod->addAttr(
4837            ObjCDirectAttr::CreateImplicit(Context, ObjCMethod->getLocation()));
4838      }
4839
4840      // There can be a single declaration in any @interface container
4841      // for a given direct method, look for clashes as we add them.
4842      //
4843      // For valid code, we should always know the primary interface
4844      // declaration by now, however for invalid code we'll keep parsing
4845      // but we won't find the primary interface and IDecl will be nil.
4846      ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(ClassDecl);
4847      if (!IDecl)
4848        IDecl = cast<ObjCCategoryDecl>(ClassDecl)->getClassInterface();
4849
4850      if (IDecl)
4851        if (auto *IMD = IDecl->lookupMethod(ObjCMethod->getSelector(),
4852                                            ObjCMethod->isInstanceMethod(),
4853                                            /*shallowCategoryLookup=*/false,
4854                                            /*followSuper=*/false)) {
4855          if (isa<ObjCProtocolDecl>(IMD->getDeclContext())) {
4856            // Do not emit a diagnostic for the Protocol case:
4857            // diag::err_objc_direct_on_protocol has already been emitted
4858            // during parsing for these with a nicer diagnostic.
4859          } else if (ObjCMethod->isDirectMethod() || IMD->isDirectMethod()) {
4860            Diag(ObjCMethod->getLocation(),
4861                 diag::err_objc_direct_duplicate_decl)
4862                << ObjCMethod->isDirectMethod() << IMD->isDirectMethod()
4863                << ObjCMethod->getDeclName();
4864            Diag(IMD->getLocation(), diag::note_previous_declaration);
4865          }
4866        }
4867    }
4868
4869    cast<DeclContext>(ClassDecl)->addDecl(ObjCMethod);
4870  }
4871
4872  if (PrevMethod) {
4873    // You can never have two method definitions with the same name.
4874    Diag(ObjCMethod->getLocation(), diag::err_duplicate_method_decl)
4875      << ObjCMethod->getDeclName();
4876    Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
4877    ObjCMethod->setInvalidDecl();
4878    return ObjCMethod;
4879  }
4880
4881  // If this Objective-C method does not have a related result type, but we
4882  // are allowed to infer related result types, try to do so based on the
4883  // method family.
4884  ObjCInterfaceDecl *CurrentClass = dyn_cast<ObjCInterfaceDecl>(ClassDecl);
4885  if (!CurrentClass) {
4886    if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(ClassDecl))
4887      CurrentClass = Cat->getClassInterface();
4888    else if (ObjCImplDecl *Impl = dyn_cast<ObjCImplDecl>(ClassDecl))
4889      CurrentClass = Impl->getClassInterface();
4890    else if (ObjCCategoryImplDecl *CatImpl
4891                                   = dyn_cast<ObjCCategoryImplDecl>(ClassDecl))
4892      CurrentClass = CatImpl->getClassInterface();
4893  }
4894
4895  ResultTypeCompatibilityKind RTC
4896    = CheckRelatedResultTypeCompatibility(*this, ObjCMethod, CurrentClass);
4897
4898  CheckObjCMethodOverrides(ObjCMethod, CurrentClass, RTC);
4899
4900  bool ARCError = false;
4901  if (getLangOpts().ObjCAutoRefCount)
4902    ARCError = CheckARCMethodDecl(ObjCMethod);
4903
4904  // Infer the related result type when possible.
4905  if (!ARCError && RTC == Sema::RTC_Compatible &&
4906      !ObjCMethod->hasRelatedResultType() &&
4907      LangOpts.ObjCInferRelatedResultType) {
4908    bool InferRelatedResultType = false;
4909    switch (ObjCMethod->getMethodFamily()) {
4910    case OMF_None:
4911    case OMF_copy:
4912    case OMF_dealloc:
4913    case OMF_finalize:
4914    case OMF_mutableCopy:
4915    case OMF_release:
4916    case OMF_retainCount:
4917    case OMF_initialize:
4918    case OMF_performSelector:
4919      break;
4920
4921    case OMF_alloc:
4922    case OMF_new:
4923        InferRelatedResultType = ObjCMethod->isClassMethod();
4924      break;
4925
4926    case OMF_init:
4927    case OMF_autorelease:
4928    case OMF_retain:
4929    case OMF_self:
4930      InferRelatedResultType = ObjCMethod->isInstanceMethod();
4931      break;
4932    }
4933
4934    if (InferRelatedResultType &&
4935        !ObjCMethod->getReturnType()->isObjCIndependentClassType())
4936      ObjCMethod->setRelatedResultType();
4937  }
4938
4939  if (MethodDefinition &&
4940      Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86)
4941    checkObjCMethodX86VectorTypes(*this, ObjCMethod);
4942
4943  // + load method cannot have availability attributes. It get called on
4944  // startup, so it has to have the availability of the deployment target.
4945  if (const auto *attr = ObjCMethod->getAttr<AvailabilityAttr>()) {
4946    if (ObjCMethod->isClassMethod() &&
4947        ObjCMethod->getSelector().getAsString() == "load") {
4948      Diag(attr->getLocation(), diag::warn_availability_on_static_initializer)
4949          << 0;
4950      ObjCMethod->dropAttr<AvailabilityAttr>();
4951    }
4952  }
4953
4954  // Insert the invisible arguments, self and _cmd!
4955  ObjCMethod->createImplicitParams(Context, ObjCMethod->getClassInterface());
4956
4957  ActOnDocumentableDecl(ObjCMethod);
4958
4959  return ObjCMethod;
4960}
4961
4962bool Sema::CheckObjCDeclScope(Decl *D) {
4963  // Following is also an error. But it is caused by a missing @end
4964  // and diagnostic is issued elsewhere.
4965  if (isa<ObjCContainerDecl>(CurContext->getRedeclContext()))
4966    return false;
4967
4968  // If we switched context to translation unit while we are still lexically in
4969  // an objc container, it means the parser missed emitting an error.
4970  if (isa<TranslationUnitDecl>(getCurLexicalContext()->getRedeclContext()))
4971    return false;
4972
4973  Diag(D->getLocation(), diag::err_objc_decls_may_only_appear_in_global_scope);
4974  D->setInvalidDecl();
4975
4976  return true;
4977}
4978
4979/// Called whenever \@defs(ClassName) is encountered in the source.  Inserts the
4980/// instance variables of ClassName into Decls.
4981void Sema::ActOnDefs(Scope *S, Decl *TagD, SourceLocation DeclStart,
4982                     IdentifierInfo *ClassName,
4983                     SmallVectorImpl<Decl*> &Decls) {
4984  // Check that ClassName is a valid class
4985  ObjCInterfaceDecl *Class = getObjCInterfaceDecl(ClassName, DeclStart);
4986  if (!Class) {
4987    Diag(DeclStart, diag::err_undef_interface) << ClassName;
4988    return;
4989  }
4990  if (LangOpts.ObjCRuntime.isNonFragile()) {
4991    Diag(DeclStart, diag::err_atdef_nonfragile_interface);
4992    return;
4993  }
4994
4995  // Collect the instance variables
4996  SmallVector<const ObjCIvarDecl*, 32> Ivars;
4997  Context.DeepCollectObjCIvars(Class, true, Ivars);
4998  // For each ivar, create a fresh ObjCAtDefsFieldDecl.
4999  for (unsigned i = 0; i < Ivars.size(); i++) {
5000    const FieldDecl* ID = Ivars[i];
5001    RecordDecl *Record = dyn_cast<RecordDecl>(TagD);
5002    Decl *FD = ObjCAtDefsFieldDecl::Create(Context, Record,
5003                                           /*FIXME: StartL=*/ID->getLocation(),
5004                                           ID->getLocation(),
5005                                           ID->getIdentifier(), ID->getType(),
5006                                           ID->getBitWidth());
5007    Decls.push_back(FD);
5008  }
5009
5010  // Introduce all of these fields into the appropriate scope.
5011  for (SmallVectorImpl<Decl*>::iterator D = Decls.begin();
5012       D != Decls.end(); ++D) {
5013    FieldDecl *FD = cast<FieldDecl>(*D);
5014    if (getLangOpts().CPlusPlus)
5015      PushOnScopeChains(FD, S);
5016    else if (RecordDecl *Record = dyn_cast<RecordDecl>(TagD))
5017      Record->addDecl(FD);
5018  }
5019}
5020
5021/// Build a type-check a new Objective-C exception variable declaration.
5022VarDecl *Sema::BuildObjCExceptionDecl(TypeSourceInfo *TInfo, QualType T,
5023                                      SourceLocation StartLoc,
5024                                      SourceLocation IdLoc,
5025                                      IdentifierInfo *Id,
5026                                      bool Invalid) {
5027  // ISO/IEC TR 18037 S6.7.3: "The type of an object with automatic storage
5028  // duration shall not be qualified by an address-space qualifier."
5029  // Since all parameters have automatic store duration, they can not have
5030  // an address space.
5031  if (T.getAddressSpace() != LangAS::Default) {
5032    Diag(IdLoc, diag::err_arg_with_address_space);
5033    Invalid = true;
5034  }
5035
5036  // An @catch parameter must be an unqualified object pointer type;
5037  // FIXME: Recover from "NSObject foo" by inserting the * in "NSObject *foo"?
5038  if (Invalid) {
5039    // Don't do any further checking.
5040  } else if (T->isDependentType()) {
5041    // Okay: we don't know what this type will instantiate to.
5042  } else if (T->isObjCQualifiedIdType()) {
5043    Invalid = true;
5044    Diag(IdLoc, diag::err_illegal_qualifiers_on_catch_parm);
5045  } else if (T->isObjCIdType()) {
5046    // Okay: we don't know what this type will instantiate to.
5047  } else if (!T->isObjCObjectPointerType()) {
5048    Invalid = true;
5049    Diag(IdLoc, diag::err_catch_param_not_objc_type);
5050  } else if (!T->castAs<ObjCObjectPointerType>()->getInterfaceType()) {
5051    Invalid = true;
5052    Diag(IdLoc, diag::err_catch_param_not_objc_type);
5053  }
5054
5055  VarDecl *New = VarDecl::Create(Context, CurContext, StartLoc, IdLoc, Id,
5056                                 T, TInfo, SC_None);
5057  New->setExceptionVariable(true);
5058
5059  // In ARC, infer 'retaining' for variables of retainable type.
5060  if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(New))
5061    Invalid = true;
5062
5063  if (Invalid)
5064    New->setInvalidDecl();
5065  return New;
5066}
5067
5068Decl *Sema::ActOnObjCExceptionDecl(Scope *S, Declarator &D) {
5069  const DeclSpec &DS = D.getDeclSpec();
5070
5071  // We allow the "register" storage class on exception variables because
5072  // GCC did, but we drop it completely. Any other storage class is an error.
5073  if (DS.getStorageClassSpec() == DeclSpec::SCS_register) {
5074    Diag(DS.getStorageClassSpecLoc(), diag::warn_register_objc_catch_parm)
5075      << FixItHint::CreateRemoval(SourceRange(DS.getStorageClassSpecLoc()));
5076  } else if (DeclSpec::SCS SCS = DS.getStorageClassSpec()) {
5077    Diag(DS.getStorageClassSpecLoc(), diag::err_storage_spec_on_catch_parm)
5078      << DeclSpec::getSpecifierName(SCS);
5079  }
5080  if (DS.isInlineSpecified())
5081    Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
5082        << getLangOpts().CPlusPlus17;
5083  if (DeclSpec::TSCS TSCS = D.getDeclSpec().getThreadStorageClassSpec())
5084    Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
5085         diag::err_invalid_thread)
5086     << DeclSpec::getSpecifierName(TSCS);
5087  D.getMutableDeclSpec().ClearStorageClassSpecs();
5088
5089  DiagnoseFunctionSpecifiers(D.getDeclSpec());
5090
5091  // Check that there are no default arguments inside the type of this
5092  // exception object (C++ only).
5093  if (getLangOpts().CPlusPlus)
5094    CheckExtraCXXDefaultArguments(D);
5095
5096  TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
5097  QualType ExceptionType = TInfo->getType();
5098
5099  VarDecl *New = BuildObjCExceptionDecl(TInfo, ExceptionType,
5100                                        D.getSourceRange().getBegin(),
5101                                        D.getIdentifierLoc(),
5102                                        D.getIdentifier(),
5103                                        D.isInvalidType());
5104
5105  // Parameter declarators cannot be qualified (C++ [dcl.meaning]p1).
5106  if (D.getCXXScopeSpec().isSet()) {
5107    Diag(D.getIdentifierLoc(), diag::err_qualified_objc_catch_parm)
5108      << D.getCXXScopeSpec().getRange();
5109    New->setInvalidDecl();
5110  }
5111
5112  // Add the parameter declaration into this scope.
5113  S->AddDecl(New);
5114  if (D.getIdentifier())
5115    IdResolver.AddDecl(New);
5116
5117  ProcessDeclAttributes(S, New, D);
5118
5119  if (New->hasAttr<BlocksAttr>())
5120    Diag(New->getLocation(), diag::err_block_on_nonlocal);
5121  return New;
5122}
5123
5124/// CollectIvarsToConstructOrDestruct - Collect those ivars which require
5125/// initialization.
5126void Sema::CollectIvarsToConstructOrDestruct(ObjCInterfaceDecl *OI,
5127                                SmallVectorImpl<ObjCIvarDecl*> &Ivars) {
5128  for (ObjCIvarDecl *Iv = OI->all_declared_ivar_begin(); Iv;
5129       Iv= Iv->getNextIvar()) {
5130    QualType QT = Context.getBaseElementType(Iv->getType());
5131    if (QT->isRecordType())
5132      Ivars.push_back(Iv);
5133  }
5134}
5135
5136void Sema::DiagnoseUseOfUnimplementedSelectors() {
5137  // Load referenced selectors from the external source.
5138  if (ExternalSource) {
5139    SmallVector<std::pair<Selector, SourceLocation>, 4> Sels;
5140    ExternalSource->ReadReferencedSelectors(Sels);
5141    for (unsigned I = 0, N = Sels.size(); I != N; ++I)
5142      ReferencedSelectors[Sels[I].first] = Sels[I].second;
5143  }
5144
5145  // Warning will be issued only when selector table is
5146  // generated (which means there is at lease one implementation
5147  // in the TU). This is to match gcc's behavior.
5148  if (ReferencedSelectors.empty() ||
5149      !Context.AnyObjCImplementation())
5150    return;
5151  for (auto &SelectorAndLocation : ReferencedSelectors) {
5152    Selector Sel = SelectorAndLocation.first;
5153    SourceLocation Loc = SelectorAndLocation.second;
5154    if (!LookupImplementedMethodInGlobalPool(Sel))
5155      Diag(Loc, diag::warn_unimplemented_selector) << Sel;
5156  }
5157}
5158
5159ObjCIvarDecl *
5160Sema::GetIvarBackingPropertyAccessor(const ObjCMethodDecl *Method,
5161                                     const ObjCPropertyDecl *&PDecl) const {
5162  if (Method->isClassMethod())
5163    return nullptr;
5164  const ObjCInterfaceDecl *IDecl = Method->getClassInterface();
5165  if (!IDecl)
5166    return nullptr;
5167  Method = IDecl->lookupMethod(Method->getSelector(), /*isInstance=*/true,
5168                               /*shallowCategoryLookup=*/false,
5169                               /*followSuper=*/false);
5170  if (!Method || !Method->isPropertyAccessor())
5171    return nullptr;
5172  if ((PDecl = Method->findPropertyDecl()))
5173    if (ObjCIvarDecl *IV = PDecl->getPropertyIvarDecl()) {
5174      // property backing ivar must belong to property's class
5175      // or be a private ivar in class's implementation.
5176      // FIXME. fix the const-ness issue.
5177      IV = const_cast<ObjCInterfaceDecl *>(IDecl)->lookupInstanceVariable(
5178                                                        IV->getIdentifier());
5179      return IV;
5180    }
5181  return nullptr;
5182}
5183
5184namespace {
5185  /// Used by Sema::DiagnoseUnusedBackingIvarInAccessor to check if a property
5186  /// accessor references the backing ivar.
5187  class UnusedBackingIvarChecker :
5188      public RecursiveASTVisitor<UnusedBackingIvarChecker> {
5189  public:
5190    Sema &S;
5191    const ObjCMethodDecl *Method;
5192    const ObjCIvarDecl *IvarD;
5193    bool AccessedIvar;
5194    bool InvokedSelfMethod;
5195
5196    UnusedBackingIvarChecker(Sema &S, const ObjCMethodDecl *Method,
5197                             const ObjCIvarDecl *IvarD)
5198      : S(S), Method(Method), IvarD(IvarD),
5199        AccessedIvar(false), InvokedSelfMethod(false) {
5200      assert(IvarD);
5201    }
5202
5203    bool VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
5204      if (E->getDecl() == IvarD) {
5205        AccessedIvar = true;
5206        return false;
5207      }
5208      return true;
5209    }
5210
5211    bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
5212      if (E->getReceiverKind() == ObjCMessageExpr::Instance &&
5213          S.isSelfExpr(E->getInstanceReceiver(), Method)) {
5214        InvokedSelfMethod = true;
5215      }
5216      return true;
5217    }
5218  };
5219} // end anonymous namespace
5220
5221void Sema::DiagnoseUnusedBackingIvarInAccessor(Scope *S,
5222                                          const ObjCImplementationDecl *ImplD) {
5223  if (S->hasUnrecoverableErrorOccurred())
5224    return;
5225
5226  for (const auto *CurMethod : ImplD->instance_methods()) {
5227    unsigned DIAG = diag::warn_unused_property_backing_ivar;
5228    SourceLocation Loc = CurMethod->getLocation();
5229    if (Diags.isIgnored(DIAG, Loc))
5230      continue;
5231
5232    const ObjCPropertyDecl *PDecl;
5233    const ObjCIvarDecl *IV = GetIvarBackingPropertyAccessor(CurMethod, PDecl);
5234    if (!IV)
5235      continue;
5236
5237    if (CurMethod->isSynthesizedAccessorStub())
5238      continue;
5239
5240    UnusedBackingIvarChecker Checker(*this, CurMethod, IV);
5241    Checker.TraverseStmt(CurMethod->getBody());
5242    if (Checker.AccessedIvar)
5243      continue;
5244
5245    // Do not issue this warning if backing ivar is used somewhere and accessor
5246    // implementation makes a self call. This is to prevent false positive in
5247    // cases where the ivar is accessed by another method that the accessor
5248    // delegates to.
5249    if (!IV->isReferenced() || !Checker.InvokedSelfMethod) {
5250      Diag(Loc, DIAG) << IV;
5251      Diag(PDecl->getLocation(), diag::note_property_declare);
5252    }
5253  }
5254}
5255