1 //===--- SemaObjCProperty.cpp - Semantic Analysis for ObjC @property ------===//
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 @property and
10 //  @synthesize declarations.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Sema/SemaInternal.h"
15 #include "clang/AST/ASTMutationListener.h"
16 #include "clang/AST/DeclObjC.h"
17 #include "clang/AST/ExprCXX.h"
18 #include "clang/AST/ExprObjC.h"
19 #include "clang/Basic/SourceManager.h"
20 #include "clang/Lex/Lexer.h"
21 #include "clang/Lex/Preprocessor.h"
22 #include "clang/Sema/Initialization.h"
23 #include "llvm/ADT/DenseSet.h"
24 #include "llvm/ADT/SmallString.h"
25 
26 using namespace clang;
27 
28 //===----------------------------------------------------------------------===//
29 // Grammar actions.
30 //===----------------------------------------------------------------------===//
31 
32 /// getImpliedARCOwnership - Given a set of property attributes and a
33 /// type, infer an expected lifetime.  The type's ownership qualification
34 /// is not considered.
35 ///
36 /// Returns OCL_None if the attributes as stated do not imply an ownership.
37 /// Never returns OCL_Autoreleasing.
38 static Qualifiers::ObjCLifetime getImpliedARCOwnership(
39                                ObjCPropertyDecl::PropertyAttributeKind attrs,
40                                                 QualType type) {
41   // retain, strong, copy, weak, and unsafe_unretained are only legal
42   // on properties of retainable pointer type.
43   if (attrs & (ObjCPropertyDecl::OBJC_PR_retain |
44                ObjCPropertyDecl::OBJC_PR_strong |
45                ObjCPropertyDecl::OBJC_PR_copy)) {
46     return Qualifiers::OCL_Strong;
47   } else if (attrs & ObjCPropertyDecl::OBJC_PR_weak) {
48     return Qualifiers::OCL_Weak;
49   } else if (attrs & ObjCPropertyDecl::OBJC_PR_unsafe_unretained) {
50     return Qualifiers::OCL_ExplicitNone;
51   }
52 
53   // assign can appear on other types, so we have to check the
54   // property type.
55   if (attrs & ObjCPropertyDecl::OBJC_PR_assign &&
56       type->isObjCRetainableType()) {
57     return Qualifiers::OCL_ExplicitNone;
58   }
59 
60   return Qualifiers::OCL_None;
61 }
62 
63 /// Check the internal consistency of a property declaration with
64 /// an explicit ownership qualifier.
65 static void checkPropertyDeclWithOwnership(Sema &S,
66                                            ObjCPropertyDecl *property) {
67   if (property->isInvalidDecl()) return;
68 
69   ObjCPropertyDecl::PropertyAttributeKind propertyKind
70     = property->getPropertyAttributes();
71   Qualifiers::ObjCLifetime propertyLifetime
72     = property->getType().getObjCLifetime();
73 
74   assert(propertyLifetime != Qualifiers::OCL_None);
75 
76   Qualifiers::ObjCLifetime expectedLifetime
77     = getImpliedARCOwnership(propertyKind, property->getType());
78   if (!expectedLifetime) {
79     // We have a lifetime qualifier but no dominating property
80     // attribute.  That's okay, but restore reasonable invariants by
81     // setting the property attribute according to the lifetime
82     // qualifier.
83     ObjCPropertyDecl::PropertyAttributeKind attr;
84     if (propertyLifetime == Qualifiers::OCL_Strong) {
85       attr = ObjCPropertyDecl::OBJC_PR_strong;
86     } else if (propertyLifetime == Qualifiers::OCL_Weak) {
87       attr = ObjCPropertyDecl::OBJC_PR_weak;
88     } else {
89       assert(propertyLifetime == Qualifiers::OCL_ExplicitNone);
90       attr = ObjCPropertyDecl::OBJC_PR_unsafe_unretained;
91     }
92     property->setPropertyAttributes(attr);
93     return;
94   }
95 
96   if (propertyLifetime == expectedLifetime) return;
97 
98   property->setInvalidDecl();
99   S.Diag(property->getLocation(),
100          diag::err_arc_inconsistent_property_ownership)
101     << property->getDeclName()
102     << expectedLifetime
103     << propertyLifetime;
104 }
105 
106 /// Check this Objective-C property against a property declared in the
107 /// given protocol.
108 static void
109 CheckPropertyAgainstProtocol(Sema &S, ObjCPropertyDecl *Prop,
110                              ObjCProtocolDecl *Proto,
111                              llvm::SmallPtrSetImpl<ObjCProtocolDecl *> &Known) {
112   // Have we seen this protocol before?
113   if (!Known.insert(Proto).second)
114     return;
115 
116   // Look for a property with the same name.
117   DeclContext::lookup_result R = Proto->lookup(Prop->getDeclName());
118   for (unsigned I = 0, N = R.size(); I != N; ++I) {
119     if (ObjCPropertyDecl *ProtoProp = dyn_cast<ObjCPropertyDecl>(R[I])) {
120       S.DiagnosePropertyMismatch(Prop, ProtoProp, Proto->getIdentifier(), true);
121       return;
122     }
123   }
124 
125   // Check this property against any protocols we inherit.
126   for (auto *P : Proto->protocols())
127     CheckPropertyAgainstProtocol(S, Prop, P, Known);
128 }
129 
130 static unsigned deducePropertyOwnershipFromType(Sema &S, QualType T) {
131   // In GC mode, just look for the __weak qualifier.
132   if (S.getLangOpts().getGC() != LangOptions::NonGC) {
133     if (T.isObjCGCWeak()) return ObjCDeclSpec::DQ_PR_weak;
134 
135   // In ARC/MRC, look for an explicit ownership qualifier.
136   // For some reason, this only applies to __weak.
137   } else if (auto ownership = T.getObjCLifetime()) {
138     switch (ownership) {
139     case Qualifiers::OCL_Weak:
140       return ObjCDeclSpec::DQ_PR_weak;
141     case Qualifiers::OCL_Strong:
142       return ObjCDeclSpec::DQ_PR_strong;
143     case Qualifiers::OCL_ExplicitNone:
144       return ObjCDeclSpec::DQ_PR_unsafe_unretained;
145     case Qualifiers::OCL_Autoreleasing:
146     case Qualifiers::OCL_None:
147       return 0;
148     }
149     llvm_unreachable("bad qualifier");
150   }
151 
152   return 0;
153 }
154 
155 static const unsigned OwnershipMask =
156   (ObjCPropertyDecl::OBJC_PR_assign |
157    ObjCPropertyDecl::OBJC_PR_retain |
158    ObjCPropertyDecl::OBJC_PR_copy   |
159    ObjCPropertyDecl::OBJC_PR_weak   |
160    ObjCPropertyDecl::OBJC_PR_strong |
161    ObjCPropertyDecl::OBJC_PR_unsafe_unretained);
162 
163 static unsigned getOwnershipRule(unsigned attr) {
164   unsigned result = attr & OwnershipMask;
165 
166   // From an ownership perspective, assign and unsafe_unretained are
167   // identical; make sure one also implies the other.
168   if (result & (ObjCPropertyDecl::OBJC_PR_assign |
169                 ObjCPropertyDecl::OBJC_PR_unsafe_unretained)) {
170     result |= ObjCPropertyDecl::OBJC_PR_assign |
171               ObjCPropertyDecl::OBJC_PR_unsafe_unretained;
172   }
173 
174   return result;
175 }
176 
177 Decl *Sema::ActOnProperty(Scope *S, SourceLocation AtLoc,
178                           SourceLocation LParenLoc,
179                           FieldDeclarator &FD,
180                           ObjCDeclSpec &ODS,
181                           Selector GetterSel,
182                           Selector SetterSel,
183                           tok::ObjCKeywordKind MethodImplKind,
184                           DeclContext *lexicalDC) {
185   unsigned Attributes = ODS.getPropertyAttributes();
186   FD.D.setObjCWeakProperty((Attributes & ObjCDeclSpec::DQ_PR_weak) != 0);
187   TypeSourceInfo *TSI = GetTypeForDeclarator(FD.D, S);
188   QualType T = TSI->getType();
189   if (!getOwnershipRule(Attributes)) {
190     Attributes |= deducePropertyOwnershipFromType(*this, T);
191   }
192   bool isReadWrite = ((Attributes & ObjCDeclSpec::DQ_PR_readwrite) ||
193                       // default is readwrite!
194                       !(Attributes & ObjCDeclSpec::DQ_PR_readonly));
195 
196   // Proceed with constructing the ObjCPropertyDecls.
197   ObjCContainerDecl *ClassDecl = cast<ObjCContainerDecl>(CurContext);
198   ObjCPropertyDecl *Res = nullptr;
199   if (ObjCCategoryDecl *CDecl = dyn_cast<ObjCCategoryDecl>(ClassDecl)) {
200     if (CDecl->IsClassExtension()) {
201       Res = HandlePropertyInClassExtension(S, AtLoc, LParenLoc,
202                                            FD,
203                                            GetterSel, ODS.getGetterNameLoc(),
204                                            SetterSel, ODS.getSetterNameLoc(),
205                                            isReadWrite, Attributes,
206                                            ODS.getPropertyAttributes(),
207                                            T, TSI, MethodImplKind);
208       if (!Res)
209         return nullptr;
210     }
211   }
212 
213   if (!Res) {
214     Res = CreatePropertyDecl(S, ClassDecl, AtLoc, LParenLoc, FD,
215                              GetterSel, ODS.getGetterNameLoc(), SetterSel,
216                              ODS.getSetterNameLoc(), isReadWrite, Attributes,
217                              ODS.getPropertyAttributes(), T, TSI,
218                              MethodImplKind);
219     if (lexicalDC)
220       Res->setLexicalDeclContext(lexicalDC);
221   }
222 
223   // Validate the attributes on the @property.
224   CheckObjCPropertyAttributes(Res, AtLoc, Attributes,
225                               (isa<ObjCInterfaceDecl>(ClassDecl) ||
226                                isa<ObjCProtocolDecl>(ClassDecl)));
227 
228   // Check consistency if the type has explicit ownership qualification.
229   if (Res->getType().getObjCLifetime())
230     checkPropertyDeclWithOwnership(*this, Res);
231 
232   llvm::SmallPtrSet<ObjCProtocolDecl *, 16> KnownProtos;
233   if (ObjCInterfaceDecl *IFace = dyn_cast<ObjCInterfaceDecl>(ClassDecl)) {
234     // For a class, compare the property against a property in our superclass.
235     bool FoundInSuper = false;
236     ObjCInterfaceDecl *CurrentInterfaceDecl = IFace;
237     while (ObjCInterfaceDecl *Super = CurrentInterfaceDecl->getSuperClass()) {
238       DeclContext::lookup_result R = Super->lookup(Res->getDeclName());
239       for (unsigned I = 0, N = R.size(); I != N; ++I) {
240         if (ObjCPropertyDecl *SuperProp = dyn_cast<ObjCPropertyDecl>(R[I])) {
241           DiagnosePropertyMismatch(Res, SuperProp, Super->getIdentifier(), false);
242           FoundInSuper = true;
243           break;
244         }
245       }
246       if (FoundInSuper)
247         break;
248       else
249         CurrentInterfaceDecl = Super;
250     }
251 
252     if (FoundInSuper) {
253       // Also compare the property against a property in our protocols.
254       for (auto *P : CurrentInterfaceDecl->protocols()) {
255         CheckPropertyAgainstProtocol(*this, Res, P, KnownProtos);
256       }
257     } else {
258       // Slower path: look in all protocols we referenced.
259       for (auto *P : IFace->all_referenced_protocols()) {
260         CheckPropertyAgainstProtocol(*this, Res, P, KnownProtos);
261       }
262     }
263   } else if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(ClassDecl)) {
264     // We don't check if class extension. Because properties in class extension
265     // are meant to override some of the attributes and checking has already done
266     // when property in class extension is constructed.
267     if (!Cat->IsClassExtension())
268       for (auto *P : Cat->protocols())
269         CheckPropertyAgainstProtocol(*this, Res, P, KnownProtos);
270   } else {
271     ObjCProtocolDecl *Proto = cast<ObjCProtocolDecl>(ClassDecl);
272     for (auto *P : Proto->protocols())
273       CheckPropertyAgainstProtocol(*this, Res, P, KnownProtos);
274   }
275 
276   ActOnDocumentableDecl(Res);
277   return Res;
278 }
279 
280 static ObjCPropertyDecl::PropertyAttributeKind
281 makePropertyAttributesAsWritten(unsigned Attributes) {
282   unsigned attributesAsWritten = 0;
283   if (Attributes & ObjCDeclSpec::DQ_PR_readonly)
284     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_readonly;
285   if (Attributes & ObjCDeclSpec::DQ_PR_readwrite)
286     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_readwrite;
287   if (Attributes & ObjCDeclSpec::DQ_PR_getter)
288     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_getter;
289   if (Attributes & ObjCDeclSpec::DQ_PR_setter)
290     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_setter;
291   if (Attributes & ObjCDeclSpec::DQ_PR_assign)
292     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_assign;
293   if (Attributes & ObjCDeclSpec::DQ_PR_retain)
294     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_retain;
295   if (Attributes & ObjCDeclSpec::DQ_PR_strong)
296     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_strong;
297   if (Attributes & ObjCDeclSpec::DQ_PR_weak)
298     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_weak;
299   if (Attributes & ObjCDeclSpec::DQ_PR_copy)
300     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_copy;
301   if (Attributes & ObjCDeclSpec::DQ_PR_unsafe_unretained)
302     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_unsafe_unretained;
303   if (Attributes & ObjCDeclSpec::DQ_PR_nonatomic)
304     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_nonatomic;
305   if (Attributes & ObjCDeclSpec::DQ_PR_atomic)
306     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_atomic;
307   if (Attributes & ObjCDeclSpec::DQ_PR_class)
308     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_class;
309   if (Attributes & ObjCDeclSpec::DQ_PR_direct)
310     attributesAsWritten |= ObjCPropertyDecl::OBJC_PR_direct;
311 
312   return (ObjCPropertyDecl::PropertyAttributeKind)attributesAsWritten;
313 }
314 
315 static bool LocPropertyAttribute( ASTContext &Context, const char *attrName,
316                                  SourceLocation LParenLoc, SourceLocation &Loc) {
317   if (LParenLoc.isMacroID())
318     return false;
319 
320   SourceManager &SM = Context.getSourceManager();
321   std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(LParenLoc);
322   // Try to load the file buffer.
323   bool invalidTemp = false;
324   StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
325   if (invalidTemp)
326     return false;
327   const char *tokenBegin = file.data() + locInfo.second;
328 
329   // Lex from the start of the given location.
330   Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
331               Context.getLangOpts(),
332               file.begin(), tokenBegin, file.end());
333   Token Tok;
334   do {
335     lexer.LexFromRawLexer(Tok);
336     if (Tok.is(tok::raw_identifier) && Tok.getRawIdentifier() == attrName) {
337       Loc = Tok.getLocation();
338       return true;
339     }
340   } while (Tok.isNot(tok::r_paren));
341   return false;
342 }
343 
344 /// Check for a mismatch in the atomicity of the given properties.
345 static void checkAtomicPropertyMismatch(Sema &S,
346                                         ObjCPropertyDecl *OldProperty,
347                                         ObjCPropertyDecl *NewProperty,
348                                         bool PropagateAtomicity) {
349   // If the atomicity of both matches, we're done.
350   bool OldIsAtomic =
351     (OldProperty->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_nonatomic)
352       == 0;
353   bool NewIsAtomic =
354     (NewProperty->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_nonatomic)
355       == 0;
356   if (OldIsAtomic == NewIsAtomic) return;
357 
358   // Determine whether the given property is readonly and implicitly
359   // atomic.
360   auto isImplicitlyReadonlyAtomic = [](ObjCPropertyDecl *Property) -> bool {
361     // Is it readonly?
362     auto Attrs = Property->getPropertyAttributes();
363     if ((Attrs & ObjCPropertyDecl::OBJC_PR_readonly) == 0) return false;
364 
365     // Is it nonatomic?
366     if (Attrs & ObjCPropertyDecl::OBJC_PR_nonatomic) return false;
367 
368     // Was 'atomic' specified directly?
369     if (Property->getPropertyAttributesAsWritten() &
370           ObjCPropertyDecl::OBJC_PR_atomic)
371       return false;
372 
373     return true;
374   };
375 
376   // If we're allowed to propagate atomicity, and the new property did
377   // not specify atomicity at all, propagate.
378   const unsigned AtomicityMask =
379     (ObjCPropertyDecl::OBJC_PR_atomic | ObjCPropertyDecl::OBJC_PR_nonatomic);
380   if (PropagateAtomicity &&
381       ((NewProperty->getPropertyAttributesAsWritten() & AtomicityMask) == 0)) {
382     unsigned Attrs = NewProperty->getPropertyAttributes();
383     Attrs = Attrs & ~AtomicityMask;
384     if (OldIsAtomic)
385       Attrs |= ObjCPropertyDecl::OBJC_PR_atomic;
386     else
387       Attrs |= ObjCPropertyDecl::OBJC_PR_nonatomic;
388 
389     NewProperty->overwritePropertyAttributes(Attrs);
390     return;
391   }
392 
393   // One of the properties is atomic; if it's a readonly property, and
394   // 'atomic' wasn't explicitly specified, we're okay.
395   if ((OldIsAtomic && isImplicitlyReadonlyAtomic(OldProperty)) ||
396       (NewIsAtomic && isImplicitlyReadonlyAtomic(NewProperty)))
397     return;
398 
399   // Diagnose the conflict.
400   const IdentifierInfo *OldContextName;
401   auto *OldDC = OldProperty->getDeclContext();
402   if (auto Category = dyn_cast<ObjCCategoryDecl>(OldDC))
403     OldContextName = Category->getClassInterface()->getIdentifier();
404   else
405     OldContextName = cast<ObjCContainerDecl>(OldDC)->getIdentifier();
406 
407   S.Diag(NewProperty->getLocation(), diag::warn_property_attribute)
408     << NewProperty->getDeclName() << "atomic"
409     << OldContextName;
410   S.Diag(OldProperty->getLocation(), diag::note_property_declare);
411 }
412 
413 ObjCPropertyDecl *
414 Sema::HandlePropertyInClassExtension(Scope *S,
415                                      SourceLocation AtLoc,
416                                      SourceLocation LParenLoc,
417                                      FieldDeclarator &FD,
418                                      Selector GetterSel,
419                                      SourceLocation GetterNameLoc,
420                                      Selector SetterSel,
421                                      SourceLocation SetterNameLoc,
422                                      const bool isReadWrite,
423                                      unsigned &Attributes,
424                                      const unsigned AttributesAsWritten,
425                                      QualType T,
426                                      TypeSourceInfo *TSI,
427                                      tok::ObjCKeywordKind MethodImplKind) {
428   ObjCCategoryDecl *CDecl = cast<ObjCCategoryDecl>(CurContext);
429   // Diagnose if this property is already in continuation class.
430   DeclContext *DC = CurContext;
431   IdentifierInfo *PropertyId = FD.D.getIdentifier();
432   ObjCInterfaceDecl *CCPrimary = CDecl->getClassInterface();
433 
434   // We need to look in the @interface to see if the @property was
435   // already declared.
436   if (!CCPrimary) {
437     Diag(CDecl->getLocation(), diag::err_continuation_class);
438     return nullptr;
439   }
440 
441   bool isClassProperty = (AttributesAsWritten & ObjCDeclSpec::DQ_PR_class) ||
442                          (Attributes & ObjCDeclSpec::DQ_PR_class);
443 
444   // Find the property in the extended class's primary class or
445   // extensions.
446   ObjCPropertyDecl *PIDecl = CCPrimary->FindPropertyVisibleInPrimaryClass(
447       PropertyId, ObjCPropertyDecl::getQueryKind(isClassProperty));
448 
449   // If we found a property in an extension, complain.
450   if (PIDecl && isa<ObjCCategoryDecl>(PIDecl->getDeclContext())) {
451     Diag(AtLoc, diag::err_duplicate_property);
452     Diag(PIDecl->getLocation(), diag::note_property_declare);
453     return nullptr;
454   }
455 
456   // Check for consistency with the previous declaration, if there is one.
457   if (PIDecl) {
458     // A readonly property declared in the primary class can be refined
459     // by adding a readwrite property within an extension.
460     // Anything else is an error.
461     if (!(PIDecl->isReadOnly() && isReadWrite)) {
462       // Tailor the diagnostics for the common case where a readwrite
463       // property is declared both in the @interface and the continuation.
464       // This is a common error where the user often intended the original
465       // declaration to be readonly.
466       unsigned diag =
467         (Attributes & ObjCDeclSpec::DQ_PR_readwrite) &&
468         (PIDecl->getPropertyAttributesAsWritten() &
469            ObjCPropertyDecl::OBJC_PR_readwrite)
470         ? diag::err_use_continuation_class_redeclaration_readwrite
471         : diag::err_use_continuation_class;
472       Diag(AtLoc, diag)
473         << CCPrimary->getDeclName();
474       Diag(PIDecl->getLocation(), diag::note_property_declare);
475       return nullptr;
476     }
477 
478     // Check for consistency of getters.
479     if (PIDecl->getGetterName() != GetterSel) {
480      // If the getter was written explicitly, complain.
481       if (AttributesAsWritten & ObjCDeclSpec::DQ_PR_getter) {
482         Diag(AtLoc, diag::warn_property_redecl_getter_mismatch)
483           << PIDecl->getGetterName() << GetterSel;
484         Diag(PIDecl->getLocation(), diag::note_property_declare);
485       }
486 
487       // Always adopt the getter from the original declaration.
488       GetterSel = PIDecl->getGetterName();
489       Attributes |= ObjCDeclSpec::DQ_PR_getter;
490     }
491 
492     // Check consistency of ownership.
493     unsigned ExistingOwnership
494       = getOwnershipRule(PIDecl->getPropertyAttributes());
495     unsigned NewOwnership = getOwnershipRule(Attributes);
496     if (ExistingOwnership && NewOwnership != ExistingOwnership) {
497       // If the ownership was written explicitly, complain.
498       if (getOwnershipRule(AttributesAsWritten)) {
499         Diag(AtLoc, diag::warn_property_attr_mismatch);
500         Diag(PIDecl->getLocation(), diag::note_property_declare);
501       }
502 
503       // Take the ownership from the original property.
504       Attributes = (Attributes & ~OwnershipMask) | ExistingOwnership;
505     }
506 
507     // If the redeclaration is 'weak' but the original property is not,
508     if ((Attributes & ObjCPropertyDecl::OBJC_PR_weak) &&
509         !(PIDecl->getPropertyAttributesAsWritten()
510             & ObjCPropertyDecl::OBJC_PR_weak) &&
511         PIDecl->getType()->getAs<ObjCObjectPointerType>() &&
512         PIDecl->getType().getObjCLifetime() == Qualifiers::OCL_None) {
513       Diag(AtLoc, diag::warn_property_implicitly_mismatched);
514       Diag(PIDecl->getLocation(), diag::note_property_declare);
515     }
516   }
517 
518   // Create a new ObjCPropertyDecl with the DeclContext being
519   // the class extension.
520   ObjCPropertyDecl *PDecl = CreatePropertyDecl(S, CDecl, AtLoc, LParenLoc,
521                                                FD, GetterSel, GetterNameLoc,
522                                                SetterSel, SetterNameLoc,
523                                                isReadWrite,
524                                                Attributes, AttributesAsWritten,
525                                                T, TSI, MethodImplKind, DC);
526 
527   // If there was no declaration of a property with the same name in
528   // the primary class, we're done.
529   if (!PIDecl) {
530     ProcessPropertyDecl(PDecl);
531     return PDecl;
532   }
533 
534   if (!Context.hasSameType(PIDecl->getType(), PDecl->getType())) {
535     bool IncompatibleObjC = false;
536     QualType ConvertedType;
537     // Relax the strict type matching for property type in continuation class.
538     // Allow property object type of continuation class to be different as long
539     // as it narrows the object type in its primary class property. Note that
540     // this conversion is safe only because the wider type is for a 'readonly'
541     // property in primary class and 'narrowed' type for a 'readwrite' property
542     // in continuation class.
543     QualType PrimaryClassPropertyT = Context.getCanonicalType(PIDecl->getType());
544     QualType ClassExtPropertyT = Context.getCanonicalType(PDecl->getType());
545     if (!isa<ObjCObjectPointerType>(PrimaryClassPropertyT) ||
546         !isa<ObjCObjectPointerType>(ClassExtPropertyT) ||
547         (!isObjCPointerConversion(ClassExtPropertyT, PrimaryClassPropertyT,
548                                   ConvertedType, IncompatibleObjC))
549         || IncompatibleObjC) {
550       Diag(AtLoc,
551           diag::err_type_mismatch_continuation_class) << PDecl->getType();
552       Diag(PIDecl->getLocation(), diag::note_property_declare);
553       return nullptr;
554     }
555   }
556 
557   // Check that atomicity of property in class extension matches the previous
558   // declaration.
559   checkAtomicPropertyMismatch(*this, PIDecl, PDecl, true);
560 
561   // Make sure getter/setter are appropriately synthesized.
562   ProcessPropertyDecl(PDecl);
563   return PDecl;
564 }
565 
566 ObjCPropertyDecl *Sema::CreatePropertyDecl(Scope *S,
567                                            ObjCContainerDecl *CDecl,
568                                            SourceLocation AtLoc,
569                                            SourceLocation LParenLoc,
570                                            FieldDeclarator &FD,
571                                            Selector GetterSel,
572                                            SourceLocation GetterNameLoc,
573                                            Selector SetterSel,
574                                            SourceLocation SetterNameLoc,
575                                            const bool isReadWrite,
576                                            const unsigned Attributes,
577                                            const unsigned AttributesAsWritten,
578                                            QualType T,
579                                            TypeSourceInfo *TInfo,
580                                            tok::ObjCKeywordKind MethodImplKind,
581                                            DeclContext *lexicalDC){
582   IdentifierInfo *PropertyId = FD.D.getIdentifier();
583 
584   // Property defaults to 'assign' if it is readwrite, unless this is ARC
585   // and the type is retainable.
586   bool isAssign;
587   if (Attributes & (ObjCDeclSpec::DQ_PR_assign |
588                     ObjCDeclSpec::DQ_PR_unsafe_unretained)) {
589     isAssign = true;
590   } else if (getOwnershipRule(Attributes) || !isReadWrite) {
591     isAssign = false;
592   } else {
593     isAssign = (!getLangOpts().ObjCAutoRefCount ||
594                 !T->isObjCRetainableType());
595   }
596 
597   // Issue a warning if property is 'assign' as default and its
598   // object, which is gc'able conforms to NSCopying protocol
599   if (getLangOpts().getGC() != LangOptions::NonGC &&
600       isAssign && !(Attributes & ObjCDeclSpec::DQ_PR_assign)) {
601     if (const ObjCObjectPointerType *ObjPtrTy =
602           T->getAs<ObjCObjectPointerType>()) {
603       ObjCInterfaceDecl *IDecl = ObjPtrTy->getObjectType()->getInterface();
604       if (IDecl)
605         if (ObjCProtocolDecl* PNSCopying =
606             LookupProtocol(&Context.Idents.get("NSCopying"), AtLoc))
607           if (IDecl->ClassImplementsProtocol(PNSCopying, true))
608             Diag(AtLoc, diag::warn_implements_nscopying) << PropertyId;
609     }
610   }
611 
612   if (T->isObjCObjectType()) {
613     SourceLocation StarLoc = TInfo->getTypeLoc().getEndLoc();
614     StarLoc = getLocForEndOfToken(StarLoc);
615     Diag(FD.D.getIdentifierLoc(), diag::err_statically_allocated_object)
616       << FixItHint::CreateInsertion(StarLoc, "*");
617     T = Context.getObjCObjectPointerType(T);
618     SourceLocation TLoc = TInfo->getTypeLoc().getBeginLoc();
619     TInfo = Context.getTrivialTypeSourceInfo(T, TLoc);
620   }
621 
622   DeclContext *DC = CDecl;
623   ObjCPropertyDecl *PDecl = ObjCPropertyDecl::Create(Context, DC,
624                                                      FD.D.getIdentifierLoc(),
625                                                      PropertyId, AtLoc,
626                                                      LParenLoc, T, TInfo);
627 
628   bool isClassProperty = (AttributesAsWritten & ObjCDeclSpec::DQ_PR_class) ||
629                          (Attributes & ObjCDeclSpec::DQ_PR_class);
630   // Class property and instance property can have the same name.
631   if (ObjCPropertyDecl *prevDecl = ObjCPropertyDecl::findPropertyDecl(
632           DC, PropertyId, ObjCPropertyDecl::getQueryKind(isClassProperty))) {
633     Diag(PDecl->getLocation(), diag::err_duplicate_property);
634     Diag(prevDecl->getLocation(), diag::note_property_declare);
635     PDecl->setInvalidDecl();
636   }
637   else {
638     DC->addDecl(PDecl);
639     if (lexicalDC)
640       PDecl->setLexicalDeclContext(lexicalDC);
641   }
642 
643   if (T->isArrayType() || T->isFunctionType()) {
644     Diag(AtLoc, diag::err_property_type) << T;
645     PDecl->setInvalidDecl();
646   }
647 
648   ProcessDeclAttributes(S, PDecl, FD.D);
649 
650   // Regardless of setter/getter attribute, we save the default getter/setter
651   // selector names in anticipation of declaration of setter/getter methods.
652   PDecl->setGetterName(GetterSel, GetterNameLoc);
653   PDecl->setSetterName(SetterSel, SetterNameLoc);
654   PDecl->setPropertyAttributesAsWritten(
655                           makePropertyAttributesAsWritten(AttributesAsWritten));
656 
657   if (Attributes & ObjCDeclSpec::DQ_PR_readonly)
658     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_readonly);
659 
660   if (Attributes & ObjCDeclSpec::DQ_PR_getter)
661     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_getter);
662 
663   if (Attributes & ObjCDeclSpec::DQ_PR_setter)
664     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_setter);
665 
666   if (isReadWrite)
667     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_readwrite);
668 
669   if (Attributes & ObjCDeclSpec::DQ_PR_retain)
670     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_retain);
671 
672   if (Attributes & ObjCDeclSpec::DQ_PR_strong)
673     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_strong);
674 
675   if (Attributes & ObjCDeclSpec::DQ_PR_weak)
676     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_weak);
677 
678   if (Attributes & ObjCDeclSpec::DQ_PR_copy)
679     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_copy);
680 
681   if (Attributes & ObjCDeclSpec::DQ_PR_unsafe_unretained)
682     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_unsafe_unretained);
683 
684   if (isAssign)
685     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_assign);
686 
687   // In the semantic attributes, one of nonatomic or atomic is always set.
688   if (Attributes & ObjCDeclSpec::DQ_PR_nonatomic)
689     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_nonatomic);
690   else
691     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_atomic);
692 
693   // 'unsafe_unretained' is alias for 'assign'.
694   if (Attributes & ObjCDeclSpec::DQ_PR_unsafe_unretained)
695     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_assign);
696   if (isAssign)
697     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_unsafe_unretained);
698 
699   if (MethodImplKind == tok::objc_required)
700     PDecl->setPropertyImplementation(ObjCPropertyDecl::Required);
701   else if (MethodImplKind == tok::objc_optional)
702     PDecl->setPropertyImplementation(ObjCPropertyDecl::Optional);
703 
704   if (Attributes & ObjCDeclSpec::DQ_PR_nullability)
705     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_nullability);
706 
707   if (Attributes & ObjCDeclSpec::DQ_PR_null_resettable)
708     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_null_resettable);
709 
710   if (Attributes & ObjCDeclSpec::DQ_PR_class)
711     PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_class);
712 
713   if ((Attributes & ObjCDeclSpec::DQ_PR_direct) ||
714       CDecl->hasAttr<ObjCDirectMembersAttr>()) {
715     if (isa<ObjCProtocolDecl>(CDecl)) {
716       Diag(PDecl->getLocation(), diag::err_objc_direct_on_protocol) << true;
717     } else if (getLangOpts().ObjCRuntime.allowsDirectDispatch()) {
718       PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_direct);
719     } else {
720       Diag(PDecl->getLocation(), diag::warn_objc_direct_property_ignored)
721           << PDecl->getDeclName();
722     }
723   }
724 
725   return PDecl;
726 }
727 
728 static void checkARCPropertyImpl(Sema &S, SourceLocation propertyImplLoc,
729                                  ObjCPropertyDecl *property,
730                                  ObjCIvarDecl *ivar) {
731   if (property->isInvalidDecl() || ivar->isInvalidDecl()) return;
732 
733   QualType ivarType = ivar->getType();
734   Qualifiers::ObjCLifetime ivarLifetime = ivarType.getObjCLifetime();
735 
736   // The lifetime implied by the property's attributes.
737   Qualifiers::ObjCLifetime propertyLifetime =
738     getImpliedARCOwnership(property->getPropertyAttributes(),
739                            property->getType());
740 
741   // We're fine if they match.
742   if (propertyLifetime == ivarLifetime) return;
743 
744   // None isn't a valid lifetime for an object ivar in ARC, and
745   // __autoreleasing is never valid; don't diagnose twice.
746   if ((ivarLifetime == Qualifiers::OCL_None &&
747        S.getLangOpts().ObjCAutoRefCount) ||
748       ivarLifetime == Qualifiers::OCL_Autoreleasing)
749     return;
750 
751   // If the ivar is private, and it's implicitly __unsafe_unretained
752   // because of its type, then pretend it was actually implicitly
753   // __strong.  This is only sound because we're processing the
754   // property implementation before parsing any method bodies.
755   if (ivarLifetime == Qualifiers::OCL_ExplicitNone &&
756       propertyLifetime == Qualifiers::OCL_Strong &&
757       ivar->getAccessControl() == ObjCIvarDecl::Private) {
758     SplitQualType split = ivarType.split();
759     if (split.Quals.hasObjCLifetime()) {
760       assert(ivarType->isObjCARCImplicitlyUnretainedType());
761       split.Quals.setObjCLifetime(Qualifiers::OCL_Strong);
762       ivarType = S.Context.getQualifiedType(split);
763       ivar->setType(ivarType);
764       return;
765     }
766   }
767 
768   switch (propertyLifetime) {
769   case Qualifiers::OCL_Strong:
770     S.Diag(ivar->getLocation(), diag::err_arc_strong_property_ownership)
771       << property->getDeclName()
772       << ivar->getDeclName()
773       << ivarLifetime;
774     break;
775 
776   case Qualifiers::OCL_Weak:
777     S.Diag(ivar->getLocation(), diag::err_weak_property)
778       << property->getDeclName()
779       << ivar->getDeclName();
780     break;
781 
782   case Qualifiers::OCL_ExplicitNone:
783     S.Diag(ivar->getLocation(), diag::err_arc_assign_property_ownership)
784       << property->getDeclName()
785       << ivar->getDeclName()
786       << ((property->getPropertyAttributesAsWritten()
787            & ObjCPropertyDecl::OBJC_PR_assign) != 0);
788     break;
789 
790   case Qualifiers::OCL_Autoreleasing:
791     llvm_unreachable("properties cannot be autoreleasing");
792 
793   case Qualifiers::OCL_None:
794     // Any other property should be ignored.
795     return;
796   }
797 
798   S.Diag(property->getLocation(), diag::note_property_declare);
799   if (propertyImplLoc.isValid())
800     S.Diag(propertyImplLoc, diag::note_property_synthesize);
801 }
802 
803 /// setImpliedPropertyAttributeForReadOnlyProperty -
804 /// This routine evaludates life-time attributes for a 'readonly'
805 /// property with no known lifetime of its own, using backing
806 /// 'ivar's attribute, if any. If no backing 'ivar', property's
807 /// life-time is assumed 'strong'.
808 static void setImpliedPropertyAttributeForReadOnlyProperty(
809               ObjCPropertyDecl *property, ObjCIvarDecl *ivar) {
810   Qualifiers::ObjCLifetime propertyLifetime =
811     getImpliedARCOwnership(property->getPropertyAttributes(),
812                            property->getType());
813   if (propertyLifetime != Qualifiers::OCL_None)
814     return;
815 
816   if (!ivar) {
817     // if no backing ivar, make property 'strong'.
818     property->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_strong);
819     return;
820   }
821   // property assumes owenership of backing ivar.
822   QualType ivarType = ivar->getType();
823   Qualifiers::ObjCLifetime ivarLifetime = ivarType.getObjCLifetime();
824   if (ivarLifetime == Qualifiers::OCL_Strong)
825     property->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_strong);
826   else if (ivarLifetime == Qualifiers::OCL_Weak)
827     property->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_weak);
828 }
829 
830 static bool
831 isIncompatiblePropertyAttribute(unsigned Attr1, unsigned Attr2,
832                                 ObjCPropertyDecl::PropertyAttributeKind Kind) {
833   return (Attr1 & Kind) != (Attr2 & Kind);
834 }
835 
836 static bool areIncompatiblePropertyAttributes(unsigned Attr1, unsigned Attr2,
837                                               unsigned Kinds) {
838   return ((Attr1 & Kinds) != 0) != ((Attr2 & Kinds) != 0);
839 }
840 
841 /// SelectPropertyForSynthesisFromProtocols - Finds the most appropriate
842 /// property declaration that should be synthesised in all of the inherited
843 /// protocols. It also diagnoses properties declared in inherited protocols with
844 /// mismatched types or attributes, since any of them can be candidate for
845 /// synthesis.
846 static ObjCPropertyDecl *
847 SelectPropertyForSynthesisFromProtocols(Sema &S, SourceLocation AtLoc,
848                                         ObjCInterfaceDecl *ClassDecl,
849                                         ObjCPropertyDecl *Property) {
850   assert(isa<ObjCProtocolDecl>(Property->getDeclContext()) &&
851          "Expected a property from a protocol");
852   ObjCInterfaceDecl::ProtocolPropertySet ProtocolSet;
853   ObjCInterfaceDecl::PropertyDeclOrder Properties;
854   for (const auto *PI : ClassDecl->all_referenced_protocols()) {
855     if (const ObjCProtocolDecl *PDecl = PI->getDefinition())
856       PDecl->collectInheritedProtocolProperties(Property, ProtocolSet,
857                                                 Properties);
858   }
859   if (ObjCInterfaceDecl *SDecl = ClassDecl->getSuperClass()) {
860     while (SDecl) {
861       for (const auto *PI : SDecl->all_referenced_protocols()) {
862         if (const ObjCProtocolDecl *PDecl = PI->getDefinition())
863           PDecl->collectInheritedProtocolProperties(Property, ProtocolSet,
864                                                     Properties);
865       }
866       SDecl = SDecl->getSuperClass();
867     }
868   }
869 
870   if (Properties.empty())
871     return Property;
872 
873   ObjCPropertyDecl *OriginalProperty = Property;
874   size_t SelectedIndex = 0;
875   for (const auto &Prop : llvm::enumerate(Properties)) {
876     // Select the 'readwrite' property if such property exists.
877     if (Property->isReadOnly() && !Prop.value()->isReadOnly()) {
878       Property = Prop.value();
879       SelectedIndex = Prop.index();
880     }
881   }
882   if (Property != OriginalProperty) {
883     // Check that the old property is compatible with the new one.
884     Properties[SelectedIndex] = OriginalProperty;
885   }
886 
887   QualType RHSType = S.Context.getCanonicalType(Property->getType());
888   unsigned OriginalAttributes = Property->getPropertyAttributesAsWritten();
889   enum MismatchKind {
890     IncompatibleType = 0,
891     HasNoExpectedAttribute,
892     HasUnexpectedAttribute,
893     DifferentGetter,
894     DifferentSetter
895   };
896   // Represents a property from another protocol that conflicts with the
897   // selected declaration.
898   struct MismatchingProperty {
899     const ObjCPropertyDecl *Prop;
900     MismatchKind Kind;
901     StringRef AttributeName;
902   };
903   SmallVector<MismatchingProperty, 4> Mismatches;
904   for (ObjCPropertyDecl *Prop : Properties) {
905     // Verify the property attributes.
906     unsigned Attr = Prop->getPropertyAttributesAsWritten();
907     if (Attr != OriginalAttributes) {
908       auto Diag = [&](bool OriginalHasAttribute, StringRef AttributeName) {
909         MismatchKind Kind = OriginalHasAttribute ? HasNoExpectedAttribute
910                                                  : HasUnexpectedAttribute;
911         Mismatches.push_back({Prop, Kind, AttributeName});
912       };
913       // The ownership might be incompatible unless the property has no explicit
914       // ownership.
915       bool HasOwnership = (Attr & (ObjCPropertyDecl::OBJC_PR_retain |
916                                    ObjCPropertyDecl::OBJC_PR_strong |
917                                    ObjCPropertyDecl::OBJC_PR_copy |
918                                    ObjCPropertyDecl::OBJC_PR_assign |
919                                    ObjCPropertyDecl::OBJC_PR_unsafe_unretained |
920                                    ObjCPropertyDecl::OBJC_PR_weak)) != 0;
921       if (HasOwnership &&
922           isIncompatiblePropertyAttribute(OriginalAttributes, Attr,
923                                           ObjCPropertyDecl::OBJC_PR_copy)) {
924         Diag(OriginalAttributes & ObjCPropertyDecl::OBJC_PR_copy, "copy");
925         continue;
926       }
927       if (HasOwnership && areIncompatiblePropertyAttributes(
928                               OriginalAttributes, Attr,
929                               ObjCPropertyDecl::OBJC_PR_retain |
930                                   ObjCPropertyDecl::OBJC_PR_strong)) {
931         Diag(OriginalAttributes & (ObjCPropertyDecl::OBJC_PR_retain |
932                                    ObjCPropertyDecl::OBJC_PR_strong),
933              "retain (or strong)");
934         continue;
935       }
936       if (isIncompatiblePropertyAttribute(OriginalAttributes, Attr,
937                                           ObjCPropertyDecl::OBJC_PR_atomic)) {
938         Diag(OriginalAttributes & ObjCPropertyDecl::OBJC_PR_atomic, "atomic");
939         continue;
940       }
941     }
942     if (Property->getGetterName() != Prop->getGetterName()) {
943       Mismatches.push_back({Prop, DifferentGetter, ""});
944       continue;
945     }
946     if (!Property->isReadOnly() && !Prop->isReadOnly() &&
947         Property->getSetterName() != Prop->getSetterName()) {
948       Mismatches.push_back({Prop, DifferentSetter, ""});
949       continue;
950     }
951     QualType LHSType = S.Context.getCanonicalType(Prop->getType());
952     if (!S.Context.propertyTypesAreCompatible(LHSType, RHSType)) {
953       bool IncompatibleObjC = false;
954       QualType ConvertedType;
955       if (!S.isObjCPointerConversion(RHSType, LHSType, ConvertedType, IncompatibleObjC)
956           || IncompatibleObjC) {
957         Mismatches.push_back({Prop, IncompatibleType, ""});
958         continue;
959       }
960     }
961   }
962 
963   if (Mismatches.empty())
964     return Property;
965 
966   // Diagnose incompability.
967   {
968     bool HasIncompatibleAttributes = false;
969     for (const auto &Note : Mismatches)
970       HasIncompatibleAttributes =
971           Note.Kind != IncompatibleType ? true : HasIncompatibleAttributes;
972     // Promote the warning to an error if there are incompatible attributes or
973     // incompatible types together with readwrite/readonly incompatibility.
974     auto Diag = S.Diag(Property->getLocation(),
975                        Property != OriginalProperty || HasIncompatibleAttributes
976                            ? diag::err_protocol_property_mismatch
977                            : diag::warn_protocol_property_mismatch);
978     Diag << Mismatches[0].Kind;
979     switch (Mismatches[0].Kind) {
980     case IncompatibleType:
981       Diag << Property->getType();
982       break;
983     case HasNoExpectedAttribute:
984     case HasUnexpectedAttribute:
985       Diag << Mismatches[0].AttributeName;
986       break;
987     case DifferentGetter:
988       Diag << Property->getGetterName();
989       break;
990     case DifferentSetter:
991       Diag << Property->getSetterName();
992       break;
993     }
994   }
995   for (const auto &Note : Mismatches) {
996     auto Diag =
997         S.Diag(Note.Prop->getLocation(), diag::note_protocol_property_declare)
998         << Note.Kind;
999     switch (Note.Kind) {
1000     case IncompatibleType:
1001       Diag << Note.Prop->getType();
1002       break;
1003     case HasNoExpectedAttribute:
1004     case HasUnexpectedAttribute:
1005       Diag << Note.AttributeName;
1006       break;
1007     case DifferentGetter:
1008       Diag << Note.Prop->getGetterName();
1009       break;
1010     case DifferentSetter:
1011       Diag << Note.Prop->getSetterName();
1012       break;
1013     }
1014   }
1015   if (AtLoc.isValid())
1016     S.Diag(AtLoc, diag::note_property_synthesize);
1017 
1018   return Property;
1019 }
1020 
1021 /// Determine whether any storage attributes were written on the property.
1022 static bool hasWrittenStorageAttribute(ObjCPropertyDecl *Prop,
1023                                        ObjCPropertyQueryKind QueryKind) {
1024   if (Prop->getPropertyAttributesAsWritten() & OwnershipMask) return true;
1025 
1026   // If this is a readwrite property in a class extension that refines
1027   // a readonly property in the original class definition, check it as
1028   // well.
1029 
1030   // If it's a readonly property, we're not interested.
1031   if (Prop->isReadOnly()) return false;
1032 
1033   // Is it declared in an extension?
1034   auto Category = dyn_cast<ObjCCategoryDecl>(Prop->getDeclContext());
1035   if (!Category || !Category->IsClassExtension()) return false;
1036 
1037   // Find the corresponding property in the primary class definition.
1038   auto OrigClass = Category->getClassInterface();
1039   for (auto Found : OrigClass->lookup(Prop->getDeclName())) {
1040     if (ObjCPropertyDecl *OrigProp = dyn_cast<ObjCPropertyDecl>(Found))
1041       return OrigProp->getPropertyAttributesAsWritten() & OwnershipMask;
1042   }
1043 
1044   // Look through all of the protocols.
1045   for (const auto *Proto : OrigClass->all_referenced_protocols()) {
1046     if (ObjCPropertyDecl *OrigProp = Proto->FindPropertyDeclaration(
1047             Prop->getIdentifier(), QueryKind))
1048       return OrigProp->getPropertyAttributesAsWritten() & OwnershipMask;
1049   }
1050 
1051   return false;
1052 }
1053 
1054 /// Create a synthesized property accessor stub inside the \@implementation.
1055 static ObjCMethodDecl *
1056 RedeclarePropertyAccessor(ASTContext &Context, ObjCImplementationDecl *Impl,
1057                           ObjCMethodDecl *AccessorDecl, SourceLocation AtLoc,
1058                           SourceLocation PropertyLoc) {
1059   ObjCMethodDecl *Decl = AccessorDecl;
1060   ObjCMethodDecl *ImplDecl = ObjCMethodDecl::Create(
1061       Context, AtLoc, PropertyLoc, Decl->getSelector(), Decl->getReturnType(),
1062       Decl->getReturnTypeSourceInfo(), Impl, Decl->isInstanceMethod(),
1063       Decl->isVariadic(), Decl->isPropertyAccessor(), /* isSynthesized*/ true,
1064       Decl->isImplicit(), Decl->isDefined(), Decl->getImplementationControl(),
1065       Decl->hasRelatedResultType());
1066   ImplDecl->getMethodFamily();
1067   if (Decl->hasAttrs())
1068     ImplDecl->setAttrs(Decl->getAttrs());
1069   ImplDecl->setSelfDecl(Decl->getSelfDecl());
1070   ImplDecl->setCmdDecl(Decl->getCmdDecl());
1071   SmallVector<SourceLocation, 1> SelLocs;
1072   Decl->getSelectorLocs(SelLocs);
1073   ImplDecl->setMethodParams(Context, Decl->parameters(), SelLocs);
1074   ImplDecl->setLexicalDeclContext(Impl);
1075   ImplDecl->setDefined(false);
1076   return ImplDecl;
1077 }
1078 
1079 /// ActOnPropertyImplDecl - This routine performs semantic checks and
1080 /// builds the AST node for a property implementation declaration; declared
1081 /// as \@synthesize or \@dynamic.
1082 ///
1083 Decl *Sema::ActOnPropertyImplDecl(Scope *S,
1084                                   SourceLocation AtLoc,
1085                                   SourceLocation PropertyLoc,
1086                                   bool Synthesize,
1087                                   IdentifierInfo *PropertyId,
1088                                   IdentifierInfo *PropertyIvar,
1089                                   SourceLocation PropertyIvarLoc,
1090                                   ObjCPropertyQueryKind QueryKind) {
1091   ObjCContainerDecl *ClassImpDecl =
1092     dyn_cast<ObjCContainerDecl>(CurContext);
1093   // Make sure we have a context for the property implementation declaration.
1094   if (!ClassImpDecl) {
1095     Diag(AtLoc, diag::err_missing_property_context);
1096     return nullptr;
1097   }
1098   if (PropertyIvarLoc.isInvalid())
1099     PropertyIvarLoc = PropertyLoc;
1100   SourceLocation PropertyDiagLoc = PropertyLoc;
1101   if (PropertyDiagLoc.isInvalid())
1102     PropertyDiagLoc = ClassImpDecl->getBeginLoc();
1103   ObjCPropertyDecl *property = nullptr;
1104   ObjCInterfaceDecl *IDecl = nullptr;
1105   // Find the class or category class where this property must have
1106   // a declaration.
1107   ObjCImplementationDecl *IC = nullptr;
1108   ObjCCategoryImplDecl *CatImplClass = nullptr;
1109   if ((IC = dyn_cast<ObjCImplementationDecl>(ClassImpDecl))) {
1110     IDecl = IC->getClassInterface();
1111     // We always synthesize an interface for an implementation
1112     // without an interface decl. So, IDecl is always non-zero.
1113     assert(IDecl &&
1114            "ActOnPropertyImplDecl - @implementation without @interface");
1115 
1116     // Look for this property declaration in the @implementation's @interface
1117     property = IDecl->FindPropertyDeclaration(PropertyId, QueryKind);
1118     if (!property) {
1119       Diag(PropertyLoc, diag::err_bad_property_decl) << IDecl->getDeclName();
1120       return nullptr;
1121     }
1122     if (property->isClassProperty() && Synthesize) {
1123       Diag(PropertyLoc, diag::err_synthesize_on_class_property) << PropertyId;
1124       return nullptr;
1125     }
1126     unsigned PIkind = property->getPropertyAttributesAsWritten();
1127     if ((PIkind & (ObjCPropertyDecl::OBJC_PR_atomic |
1128                    ObjCPropertyDecl::OBJC_PR_nonatomic) ) == 0) {
1129       if (AtLoc.isValid())
1130         Diag(AtLoc, diag::warn_implicit_atomic_property);
1131       else
1132         Diag(IC->getLocation(), diag::warn_auto_implicit_atomic_property);
1133       Diag(property->getLocation(), diag::note_property_declare);
1134     }
1135 
1136     if (const ObjCCategoryDecl *CD =
1137         dyn_cast<ObjCCategoryDecl>(property->getDeclContext())) {
1138       if (!CD->IsClassExtension()) {
1139         Diag(PropertyLoc, diag::err_category_property) << CD->getDeclName();
1140         Diag(property->getLocation(), diag::note_property_declare);
1141         return nullptr;
1142       }
1143     }
1144     if (Synthesize&&
1145         (PIkind & ObjCPropertyDecl::OBJC_PR_readonly) &&
1146         property->hasAttr<IBOutletAttr>() &&
1147         !AtLoc.isValid()) {
1148       bool ReadWriteProperty = false;
1149       // Search into the class extensions and see if 'readonly property is
1150       // redeclared 'readwrite', then no warning is to be issued.
1151       for (auto *Ext : IDecl->known_extensions()) {
1152         DeclContext::lookup_result R = Ext->lookup(property->getDeclName());
1153         if (!R.empty())
1154           if (ObjCPropertyDecl *ExtProp = dyn_cast<ObjCPropertyDecl>(R[0])) {
1155             PIkind = ExtProp->getPropertyAttributesAsWritten();
1156             if (PIkind & ObjCPropertyDecl::OBJC_PR_readwrite) {
1157               ReadWriteProperty = true;
1158               break;
1159             }
1160           }
1161       }
1162 
1163       if (!ReadWriteProperty) {
1164         Diag(property->getLocation(), diag::warn_auto_readonly_iboutlet_property)
1165             << property;
1166         SourceLocation readonlyLoc;
1167         if (LocPropertyAttribute(Context, "readonly",
1168                                  property->getLParenLoc(), readonlyLoc)) {
1169           SourceLocation endLoc =
1170             readonlyLoc.getLocWithOffset(strlen("readonly")-1);
1171           SourceRange ReadonlySourceRange(readonlyLoc, endLoc);
1172           Diag(property->getLocation(),
1173                diag::note_auto_readonly_iboutlet_fixup_suggest) <<
1174           FixItHint::CreateReplacement(ReadonlySourceRange, "readwrite");
1175         }
1176       }
1177     }
1178     if (Synthesize && isa<ObjCProtocolDecl>(property->getDeclContext()))
1179       property = SelectPropertyForSynthesisFromProtocols(*this, AtLoc, IDecl,
1180                                                          property);
1181 
1182   } else if ((CatImplClass = dyn_cast<ObjCCategoryImplDecl>(ClassImpDecl))) {
1183     if (Synthesize) {
1184       Diag(AtLoc, diag::err_synthesize_category_decl);
1185       return nullptr;
1186     }
1187     IDecl = CatImplClass->getClassInterface();
1188     if (!IDecl) {
1189       Diag(AtLoc, diag::err_missing_property_interface);
1190       return nullptr;
1191     }
1192     ObjCCategoryDecl *Category =
1193     IDecl->FindCategoryDeclaration(CatImplClass->getIdentifier());
1194 
1195     // If category for this implementation not found, it is an error which
1196     // has already been reported eralier.
1197     if (!Category)
1198       return nullptr;
1199     // Look for this property declaration in @implementation's category
1200     property = Category->FindPropertyDeclaration(PropertyId, QueryKind);
1201     if (!property) {
1202       Diag(PropertyLoc, diag::err_bad_category_property_decl)
1203       << Category->getDeclName();
1204       return nullptr;
1205     }
1206   } else {
1207     Diag(AtLoc, diag::err_bad_property_context);
1208     return nullptr;
1209   }
1210   ObjCIvarDecl *Ivar = nullptr;
1211   bool CompleteTypeErr = false;
1212   bool compat = true;
1213   // Check that we have a valid, previously declared ivar for @synthesize
1214   if (Synthesize) {
1215     // @synthesize
1216     if (!PropertyIvar)
1217       PropertyIvar = PropertyId;
1218     // Check that this is a previously declared 'ivar' in 'IDecl' interface
1219     ObjCInterfaceDecl *ClassDeclared;
1220     Ivar = IDecl->lookupInstanceVariable(PropertyIvar, ClassDeclared);
1221     QualType PropType = property->getType();
1222     QualType PropertyIvarType = PropType.getNonReferenceType();
1223 
1224     if (RequireCompleteType(PropertyDiagLoc, PropertyIvarType,
1225                             diag::err_incomplete_synthesized_property,
1226                             property->getDeclName())) {
1227       Diag(property->getLocation(), diag::note_property_declare);
1228       CompleteTypeErr = true;
1229     }
1230 
1231     if (getLangOpts().ObjCAutoRefCount &&
1232         (property->getPropertyAttributesAsWritten() &
1233          ObjCPropertyDecl::OBJC_PR_readonly) &&
1234         PropertyIvarType->isObjCRetainableType()) {
1235       setImpliedPropertyAttributeForReadOnlyProperty(property, Ivar);
1236     }
1237 
1238     ObjCPropertyDecl::PropertyAttributeKind kind
1239       = property->getPropertyAttributes();
1240 
1241     bool isARCWeak = false;
1242     if (kind & ObjCPropertyDecl::OBJC_PR_weak) {
1243       // Add GC __weak to the ivar type if the property is weak.
1244       if (getLangOpts().getGC() != LangOptions::NonGC) {
1245         assert(!getLangOpts().ObjCAutoRefCount);
1246         if (PropertyIvarType.isObjCGCStrong()) {
1247           Diag(PropertyDiagLoc, diag::err_gc_weak_property_strong_type);
1248           Diag(property->getLocation(), diag::note_property_declare);
1249         } else {
1250           PropertyIvarType =
1251             Context.getObjCGCQualType(PropertyIvarType, Qualifiers::Weak);
1252         }
1253 
1254       // Otherwise, check whether ARC __weak is enabled and works with
1255       // the property type.
1256       } else {
1257         if (!getLangOpts().ObjCWeak) {
1258           // Only complain here when synthesizing an ivar.
1259           if (!Ivar) {
1260             Diag(PropertyDiagLoc,
1261                  getLangOpts().ObjCWeakRuntime
1262                    ? diag::err_synthesizing_arc_weak_property_disabled
1263                    : diag::err_synthesizing_arc_weak_property_no_runtime);
1264             Diag(property->getLocation(), diag::note_property_declare);
1265           }
1266           CompleteTypeErr = true; // suppress later diagnostics about the ivar
1267         } else {
1268           isARCWeak = true;
1269           if (const ObjCObjectPointerType *ObjT =
1270                 PropertyIvarType->getAs<ObjCObjectPointerType>()) {
1271             const ObjCInterfaceDecl *ObjI = ObjT->getInterfaceDecl();
1272             if (ObjI && ObjI->isArcWeakrefUnavailable()) {
1273               Diag(property->getLocation(),
1274                    diag::err_arc_weak_unavailable_property)
1275                 << PropertyIvarType;
1276               Diag(ClassImpDecl->getLocation(), diag::note_implemented_by_class)
1277                 << ClassImpDecl->getName();
1278             }
1279           }
1280         }
1281       }
1282     }
1283 
1284     if (AtLoc.isInvalid()) {
1285       // Check when default synthesizing a property that there is
1286       // an ivar matching property name and issue warning; since this
1287       // is the most common case of not using an ivar used for backing
1288       // property in non-default synthesis case.
1289       ObjCInterfaceDecl *ClassDeclared=nullptr;
1290       ObjCIvarDecl *originalIvar =
1291       IDecl->lookupInstanceVariable(property->getIdentifier(),
1292                                     ClassDeclared);
1293       if (originalIvar) {
1294         Diag(PropertyDiagLoc,
1295              diag::warn_autosynthesis_property_ivar_match)
1296         << PropertyId << (Ivar == nullptr) << PropertyIvar
1297         << originalIvar->getIdentifier();
1298         Diag(property->getLocation(), diag::note_property_declare);
1299         Diag(originalIvar->getLocation(), diag::note_ivar_decl);
1300       }
1301     }
1302 
1303     if (!Ivar) {
1304       // In ARC, give the ivar a lifetime qualifier based on the
1305       // property attributes.
1306       if ((getLangOpts().ObjCAutoRefCount || isARCWeak) &&
1307           !PropertyIvarType.getObjCLifetime() &&
1308           PropertyIvarType->isObjCRetainableType()) {
1309 
1310         // It's an error if we have to do this and the user didn't
1311         // explicitly write an ownership attribute on the property.
1312         if (!hasWrittenStorageAttribute(property, QueryKind) &&
1313             !(kind & ObjCPropertyDecl::OBJC_PR_strong)) {
1314           Diag(PropertyDiagLoc,
1315                diag::err_arc_objc_property_default_assign_on_object);
1316           Diag(property->getLocation(), diag::note_property_declare);
1317         } else {
1318           Qualifiers::ObjCLifetime lifetime =
1319             getImpliedARCOwnership(kind, PropertyIvarType);
1320           assert(lifetime && "no lifetime for property?");
1321 
1322           Qualifiers qs;
1323           qs.addObjCLifetime(lifetime);
1324           PropertyIvarType = Context.getQualifiedType(PropertyIvarType, qs);
1325         }
1326       }
1327 
1328       Ivar = ObjCIvarDecl::Create(Context, ClassImpDecl,
1329                                   PropertyIvarLoc,PropertyIvarLoc, PropertyIvar,
1330                                   PropertyIvarType, /*TInfo=*/nullptr,
1331                                   ObjCIvarDecl::Private,
1332                                   (Expr *)nullptr, true);
1333       if (RequireNonAbstractType(PropertyIvarLoc,
1334                                  PropertyIvarType,
1335                                  diag::err_abstract_type_in_decl,
1336                                  AbstractSynthesizedIvarType)) {
1337         Diag(property->getLocation(), diag::note_property_declare);
1338         // An abstract type is as bad as an incomplete type.
1339         CompleteTypeErr = true;
1340       }
1341       if (!CompleteTypeErr) {
1342         const RecordType *RecordTy = PropertyIvarType->getAs<RecordType>();
1343         if (RecordTy && RecordTy->getDecl()->hasFlexibleArrayMember()) {
1344           Diag(PropertyIvarLoc, diag::err_synthesize_variable_sized_ivar)
1345             << PropertyIvarType;
1346           CompleteTypeErr = true; // suppress later diagnostics about the ivar
1347         }
1348       }
1349       if (CompleteTypeErr)
1350         Ivar->setInvalidDecl();
1351       ClassImpDecl->addDecl(Ivar);
1352       IDecl->makeDeclVisibleInContext(Ivar);
1353 
1354       if (getLangOpts().ObjCRuntime.isFragile())
1355         Diag(PropertyDiagLoc, diag::err_missing_property_ivar_decl)
1356             << PropertyId;
1357       // Note! I deliberately want it to fall thru so, we have a
1358       // a property implementation and to avoid future warnings.
1359     } else if (getLangOpts().ObjCRuntime.isNonFragile() &&
1360                !declaresSameEntity(ClassDeclared, IDecl)) {
1361       Diag(PropertyDiagLoc, diag::err_ivar_in_superclass_use)
1362       << property->getDeclName() << Ivar->getDeclName()
1363       << ClassDeclared->getDeclName();
1364       Diag(Ivar->getLocation(), diag::note_previous_access_declaration)
1365       << Ivar << Ivar->getName();
1366       // Note! I deliberately want it to fall thru so more errors are caught.
1367     }
1368     property->setPropertyIvarDecl(Ivar);
1369 
1370     QualType IvarType = Context.getCanonicalType(Ivar->getType());
1371 
1372     // Check that type of property and its ivar are type compatible.
1373     if (!Context.hasSameType(PropertyIvarType, IvarType)) {
1374       if (isa<ObjCObjectPointerType>(PropertyIvarType)
1375           && isa<ObjCObjectPointerType>(IvarType))
1376         compat =
1377           Context.canAssignObjCInterfaces(
1378                                   PropertyIvarType->getAs<ObjCObjectPointerType>(),
1379                                   IvarType->getAs<ObjCObjectPointerType>());
1380       else {
1381         compat = (CheckAssignmentConstraints(PropertyIvarLoc, PropertyIvarType,
1382                                              IvarType)
1383                     == Compatible);
1384       }
1385       if (!compat) {
1386         Diag(PropertyDiagLoc, diag::err_property_ivar_type)
1387           << property->getDeclName() << PropType
1388           << Ivar->getDeclName() << IvarType;
1389         Diag(Ivar->getLocation(), diag::note_ivar_decl);
1390         // Note! I deliberately want it to fall thru so, we have a
1391         // a property implementation and to avoid future warnings.
1392       }
1393       else {
1394         // FIXME! Rules for properties are somewhat different that those
1395         // for assignments. Use a new routine to consolidate all cases;
1396         // specifically for property redeclarations as well as for ivars.
1397         QualType lhsType =Context.getCanonicalType(PropertyIvarType).getUnqualifiedType();
1398         QualType rhsType =Context.getCanonicalType(IvarType).getUnqualifiedType();
1399         if (lhsType != rhsType &&
1400             lhsType->isArithmeticType()) {
1401           Diag(PropertyDiagLoc, diag::err_property_ivar_type)
1402             << property->getDeclName() << PropType
1403             << Ivar->getDeclName() << IvarType;
1404           Diag(Ivar->getLocation(), diag::note_ivar_decl);
1405           // Fall thru - see previous comment
1406         }
1407       }
1408       // __weak is explicit. So it works on Canonical type.
1409       if ((PropType.isObjCGCWeak() && !IvarType.isObjCGCWeak() &&
1410            getLangOpts().getGC() != LangOptions::NonGC)) {
1411         Diag(PropertyDiagLoc, diag::err_weak_property)
1412         << property->getDeclName() << Ivar->getDeclName();
1413         Diag(Ivar->getLocation(), diag::note_ivar_decl);
1414         // Fall thru - see previous comment
1415       }
1416       // Fall thru - see previous comment
1417       if ((property->getType()->isObjCObjectPointerType() ||
1418            PropType.isObjCGCStrong()) && IvarType.isObjCGCWeak() &&
1419           getLangOpts().getGC() != LangOptions::NonGC) {
1420         Diag(PropertyDiagLoc, diag::err_strong_property)
1421         << property->getDeclName() << Ivar->getDeclName();
1422         // Fall thru - see previous comment
1423       }
1424     }
1425     if (getLangOpts().ObjCAutoRefCount || isARCWeak ||
1426         Ivar->getType().getObjCLifetime())
1427       checkARCPropertyImpl(*this, PropertyLoc, property, Ivar);
1428   } else if (PropertyIvar)
1429     // @dynamic
1430     Diag(PropertyDiagLoc, diag::err_dynamic_property_ivar_decl);
1431 
1432   assert (property && "ActOnPropertyImplDecl - property declaration missing");
1433   ObjCPropertyImplDecl *PIDecl =
1434   ObjCPropertyImplDecl::Create(Context, CurContext, AtLoc, PropertyLoc,
1435                                property,
1436                                (Synthesize ?
1437                                 ObjCPropertyImplDecl::Synthesize
1438                                 : ObjCPropertyImplDecl::Dynamic),
1439                                Ivar, PropertyIvarLoc);
1440 
1441   if (CompleteTypeErr || !compat)
1442     PIDecl->setInvalidDecl();
1443 
1444   if (ObjCMethodDecl *getterMethod = property->getGetterMethodDecl()) {
1445     getterMethod->createImplicitParams(Context, IDecl);
1446 
1447     // Redeclare the getter within the implementation as DeclContext.
1448     if (Synthesize) {
1449       // If the method hasn't been overridden, create a synthesized implementation.
1450       ObjCMethodDecl *OMD = ClassImpDecl->getMethod(
1451           getterMethod->getSelector(), getterMethod->isInstanceMethod());
1452       if (!OMD)
1453         OMD = RedeclarePropertyAccessor(Context, IC, getterMethod, AtLoc,
1454                                         PropertyLoc);
1455       PIDecl->setGetterMethodDecl(OMD);
1456     }
1457 
1458     if (getLangOpts().CPlusPlus && Synthesize && !CompleteTypeErr &&
1459         Ivar->getType()->isRecordType()) {
1460       // For Objective-C++, need to synthesize the AST for the IVAR object to be
1461       // returned by the getter as it must conform to C++'s copy-return rules.
1462       // FIXME. Eventually we want to do this for Objective-C as well.
1463       SynthesizedFunctionScope Scope(*this, getterMethod);
1464       ImplicitParamDecl *SelfDecl = getterMethod->getSelfDecl();
1465       DeclRefExpr *SelfExpr = new (Context)
1466           DeclRefExpr(Context, SelfDecl, false, SelfDecl->getType(), VK_LValue,
1467                       PropertyDiagLoc);
1468       MarkDeclRefReferenced(SelfExpr);
1469       Expr *LoadSelfExpr =
1470         ImplicitCastExpr::Create(Context, SelfDecl->getType(),
1471                                  CK_LValueToRValue, SelfExpr, nullptr,
1472                                  VK_RValue);
1473       Expr *IvarRefExpr =
1474         new (Context) ObjCIvarRefExpr(Ivar,
1475                                       Ivar->getUsageType(SelfDecl->getType()),
1476                                       PropertyDiagLoc,
1477                                       Ivar->getLocation(),
1478                                       LoadSelfExpr, true, true);
1479       ExprResult Res = PerformCopyInitialization(
1480           InitializedEntity::InitializeResult(PropertyDiagLoc,
1481                                               getterMethod->getReturnType(),
1482                                               /*NRVO=*/false),
1483           PropertyDiagLoc, IvarRefExpr);
1484       if (!Res.isInvalid()) {
1485         Expr *ResExpr = Res.getAs<Expr>();
1486         if (ResExpr)
1487           ResExpr = MaybeCreateExprWithCleanups(ResExpr);
1488         PIDecl->setGetterCXXConstructor(ResExpr);
1489       }
1490     }
1491     if (property->hasAttr<NSReturnsNotRetainedAttr>() &&
1492         !getterMethod->hasAttr<NSReturnsNotRetainedAttr>()) {
1493       Diag(getterMethod->getLocation(),
1494            diag::warn_property_getter_owning_mismatch);
1495       Diag(property->getLocation(), diag::note_property_declare);
1496     }
1497     if (getLangOpts().ObjCAutoRefCount && Synthesize)
1498       switch (getterMethod->getMethodFamily()) {
1499         case OMF_retain:
1500         case OMF_retainCount:
1501         case OMF_release:
1502         case OMF_autorelease:
1503           Diag(getterMethod->getLocation(), diag::err_arc_illegal_method_def)
1504             << 1 << getterMethod->getSelector();
1505           break;
1506         default:
1507           break;
1508       }
1509   }
1510 
1511   if (ObjCMethodDecl *setterMethod = property->getSetterMethodDecl()) {
1512     setterMethod->createImplicitParams(Context, IDecl);
1513 
1514     // Redeclare the setter within the implementation as DeclContext.
1515     if (Synthesize) {
1516       ObjCMethodDecl *OMD = ClassImpDecl->getMethod(
1517           setterMethod->getSelector(), setterMethod->isInstanceMethod());
1518       if (!OMD)
1519         OMD = RedeclarePropertyAccessor(Context, IC, setterMethod,
1520                                         AtLoc, PropertyLoc);
1521       PIDecl->setSetterMethodDecl(OMD);
1522     }
1523 
1524     if (getLangOpts().CPlusPlus && Synthesize && !CompleteTypeErr &&
1525         Ivar->getType()->isRecordType()) {
1526       // FIXME. Eventually we want to do this for Objective-C as well.
1527       SynthesizedFunctionScope Scope(*this, setterMethod);
1528       ImplicitParamDecl *SelfDecl = setterMethod->getSelfDecl();
1529       DeclRefExpr *SelfExpr = new (Context)
1530           DeclRefExpr(Context, SelfDecl, false, SelfDecl->getType(), VK_LValue,
1531                       PropertyDiagLoc);
1532       MarkDeclRefReferenced(SelfExpr);
1533       Expr *LoadSelfExpr =
1534         ImplicitCastExpr::Create(Context, SelfDecl->getType(),
1535                                  CK_LValueToRValue, SelfExpr, nullptr,
1536                                  VK_RValue);
1537       Expr *lhs =
1538         new (Context) ObjCIvarRefExpr(Ivar,
1539                                       Ivar->getUsageType(SelfDecl->getType()),
1540                                       PropertyDiagLoc,
1541                                       Ivar->getLocation(),
1542                                       LoadSelfExpr, true, true);
1543       ObjCMethodDecl::param_iterator P = setterMethod->param_begin();
1544       ParmVarDecl *Param = (*P);
1545       QualType T = Param->getType().getNonReferenceType();
1546       DeclRefExpr *rhs = new (Context)
1547           DeclRefExpr(Context, Param, false, T, VK_LValue, PropertyDiagLoc);
1548       MarkDeclRefReferenced(rhs);
1549       ExprResult Res = BuildBinOp(S, PropertyDiagLoc,
1550                                   BO_Assign, lhs, rhs);
1551       if (property->getPropertyAttributes() &
1552           ObjCPropertyDecl::OBJC_PR_atomic) {
1553         Expr *callExpr = Res.getAs<Expr>();
1554         if (const CXXOperatorCallExpr *CXXCE =
1555               dyn_cast_or_null<CXXOperatorCallExpr>(callExpr))
1556           if (const FunctionDecl *FuncDecl = CXXCE->getDirectCallee())
1557             if (!FuncDecl->isTrivial())
1558               if (property->getType()->isReferenceType()) {
1559                 Diag(PropertyDiagLoc,
1560                      diag::err_atomic_property_nontrivial_assign_op)
1561                     << property->getType();
1562                 Diag(FuncDecl->getBeginLoc(), diag::note_callee_decl)
1563                     << FuncDecl;
1564               }
1565       }
1566       PIDecl->setSetterCXXAssignment(Res.getAs<Expr>());
1567     }
1568   }
1569 
1570   if (IC) {
1571     if (Synthesize)
1572       if (ObjCPropertyImplDecl *PPIDecl =
1573           IC->FindPropertyImplIvarDecl(PropertyIvar)) {
1574         Diag(PropertyLoc, diag::err_duplicate_ivar_use)
1575         << PropertyId << PPIDecl->getPropertyDecl()->getIdentifier()
1576         << PropertyIvar;
1577         Diag(PPIDecl->getLocation(), diag::note_previous_use);
1578       }
1579 
1580     if (ObjCPropertyImplDecl *PPIDecl
1581         = IC->FindPropertyImplDecl(PropertyId, QueryKind)) {
1582       Diag(PropertyLoc, diag::err_property_implemented) << PropertyId;
1583       Diag(PPIDecl->getLocation(), diag::note_previous_declaration);
1584       return nullptr;
1585     }
1586     IC->addPropertyImplementation(PIDecl);
1587     if (getLangOpts().ObjCDefaultSynthProperties &&
1588         getLangOpts().ObjCRuntime.isNonFragile() &&
1589         !IDecl->isObjCRequiresPropertyDefs()) {
1590       // Diagnose if an ivar was lazily synthesdized due to a previous
1591       // use and if 1) property is @dynamic or 2) property is synthesized
1592       // but it requires an ivar of different name.
1593       ObjCInterfaceDecl *ClassDeclared=nullptr;
1594       ObjCIvarDecl *Ivar = nullptr;
1595       if (!Synthesize)
1596         Ivar = IDecl->lookupInstanceVariable(PropertyId, ClassDeclared);
1597       else {
1598         if (PropertyIvar && PropertyIvar != PropertyId)
1599           Ivar = IDecl->lookupInstanceVariable(PropertyId, ClassDeclared);
1600       }
1601       // Issue diagnostics only if Ivar belongs to current class.
1602       if (Ivar && Ivar->getSynthesize() &&
1603           declaresSameEntity(IC->getClassInterface(), ClassDeclared)) {
1604         Diag(Ivar->getLocation(), diag::err_undeclared_var_use)
1605         << PropertyId;
1606         Ivar->setInvalidDecl();
1607       }
1608     }
1609   } else {
1610     if (Synthesize)
1611       if (ObjCPropertyImplDecl *PPIDecl =
1612           CatImplClass->FindPropertyImplIvarDecl(PropertyIvar)) {
1613         Diag(PropertyDiagLoc, diag::err_duplicate_ivar_use)
1614         << PropertyId << PPIDecl->getPropertyDecl()->getIdentifier()
1615         << PropertyIvar;
1616         Diag(PPIDecl->getLocation(), diag::note_previous_use);
1617       }
1618 
1619     if (ObjCPropertyImplDecl *PPIDecl =
1620         CatImplClass->FindPropertyImplDecl(PropertyId, QueryKind)) {
1621       Diag(PropertyDiagLoc, diag::err_property_implemented) << PropertyId;
1622       Diag(PPIDecl->getLocation(), diag::note_previous_declaration);
1623       return nullptr;
1624     }
1625     CatImplClass->addPropertyImplementation(PIDecl);
1626   }
1627 
1628   return PIDecl;
1629 }
1630 
1631 //===----------------------------------------------------------------------===//
1632 // Helper methods.
1633 //===----------------------------------------------------------------------===//
1634 
1635 /// DiagnosePropertyMismatch - Compares two properties for their
1636 /// attributes and types and warns on a variety of inconsistencies.
1637 ///
1638 void
1639 Sema::DiagnosePropertyMismatch(ObjCPropertyDecl *Property,
1640                                ObjCPropertyDecl *SuperProperty,
1641                                const IdentifierInfo *inheritedName,
1642                                bool OverridingProtocolProperty) {
1643   ObjCPropertyDecl::PropertyAttributeKind CAttr =
1644     Property->getPropertyAttributes();
1645   ObjCPropertyDecl::PropertyAttributeKind SAttr =
1646     SuperProperty->getPropertyAttributes();
1647 
1648   // We allow readonly properties without an explicit ownership
1649   // (assign/unsafe_unretained/weak/retain/strong/copy) in super class
1650   // to be overridden by a property with any explicit ownership in the subclass.
1651   if (!OverridingProtocolProperty &&
1652       !getOwnershipRule(SAttr) && getOwnershipRule(CAttr))
1653     ;
1654   else {
1655     if ((CAttr & ObjCPropertyDecl::OBJC_PR_readonly)
1656         && (SAttr & ObjCPropertyDecl::OBJC_PR_readwrite))
1657       Diag(Property->getLocation(), diag::warn_readonly_property)
1658         << Property->getDeclName() << inheritedName;
1659     if ((CAttr & ObjCPropertyDecl::OBJC_PR_copy)
1660         != (SAttr & ObjCPropertyDecl::OBJC_PR_copy))
1661       Diag(Property->getLocation(), diag::warn_property_attribute)
1662         << Property->getDeclName() << "copy" << inheritedName;
1663     else if (!(SAttr & ObjCPropertyDecl::OBJC_PR_readonly)){
1664       unsigned CAttrRetain =
1665         (CAttr &
1666          (ObjCPropertyDecl::OBJC_PR_retain | ObjCPropertyDecl::OBJC_PR_strong));
1667       unsigned SAttrRetain =
1668         (SAttr &
1669          (ObjCPropertyDecl::OBJC_PR_retain | ObjCPropertyDecl::OBJC_PR_strong));
1670       bool CStrong = (CAttrRetain != 0);
1671       bool SStrong = (SAttrRetain != 0);
1672       if (CStrong != SStrong)
1673         Diag(Property->getLocation(), diag::warn_property_attribute)
1674           << Property->getDeclName() << "retain (or strong)" << inheritedName;
1675     }
1676   }
1677 
1678   // Check for nonatomic; note that nonatomic is effectively
1679   // meaningless for readonly properties, so don't diagnose if the
1680   // atomic property is 'readonly'.
1681   checkAtomicPropertyMismatch(*this, SuperProperty, Property, false);
1682   // Readonly properties from protocols can be implemented as "readwrite"
1683   // with a custom setter name.
1684   if (Property->getSetterName() != SuperProperty->getSetterName() &&
1685       !(SuperProperty->isReadOnly() &&
1686         isa<ObjCProtocolDecl>(SuperProperty->getDeclContext()))) {
1687     Diag(Property->getLocation(), diag::warn_property_attribute)
1688       << Property->getDeclName() << "setter" << inheritedName;
1689     Diag(SuperProperty->getLocation(), diag::note_property_declare);
1690   }
1691   if (Property->getGetterName() != SuperProperty->getGetterName()) {
1692     Diag(Property->getLocation(), diag::warn_property_attribute)
1693       << Property->getDeclName() << "getter" << inheritedName;
1694     Diag(SuperProperty->getLocation(), diag::note_property_declare);
1695   }
1696 
1697   QualType LHSType =
1698     Context.getCanonicalType(SuperProperty->getType());
1699   QualType RHSType =
1700     Context.getCanonicalType(Property->getType());
1701 
1702   if (!Context.propertyTypesAreCompatible(LHSType, RHSType)) {
1703     // Do cases not handled in above.
1704     // FIXME. For future support of covariant property types, revisit this.
1705     bool IncompatibleObjC = false;
1706     QualType ConvertedType;
1707     if (!isObjCPointerConversion(RHSType, LHSType,
1708                                  ConvertedType, IncompatibleObjC) ||
1709         IncompatibleObjC) {
1710         Diag(Property->getLocation(), diag::warn_property_types_are_incompatible)
1711         << Property->getType() << SuperProperty->getType() << inheritedName;
1712       Diag(SuperProperty->getLocation(), diag::note_property_declare);
1713     }
1714   }
1715 }
1716 
1717 bool Sema::DiagnosePropertyAccessorMismatch(ObjCPropertyDecl *property,
1718                                             ObjCMethodDecl *GetterMethod,
1719                                             SourceLocation Loc) {
1720   if (!GetterMethod)
1721     return false;
1722   QualType GetterType = GetterMethod->getReturnType().getNonReferenceType();
1723   QualType PropertyRValueType =
1724       property->getType().getNonReferenceType().getAtomicUnqualifiedType();
1725   bool compat = Context.hasSameType(PropertyRValueType, GetterType);
1726   if (!compat) {
1727     const ObjCObjectPointerType *propertyObjCPtr = nullptr;
1728     const ObjCObjectPointerType *getterObjCPtr = nullptr;
1729     if ((propertyObjCPtr =
1730              PropertyRValueType->getAs<ObjCObjectPointerType>()) &&
1731         (getterObjCPtr = GetterType->getAs<ObjCObjectPointerType>()))
1732       compat = Context.canAssignObjCInterfaces(getterObjCPtr, propertyObjCPtr);
1733     else if (CheckAssignmentConstraints(Loc, GetterType, PropertyRValueType)
1734               != Compatible) {
1735           Diag(Loc, diag::err_property_accessor_type)
1736             << property->getDeclName() << PropertyRValueType
1737             << GetterMethod->getSelector() << GetterType;
1738           Diag(GetterMethod->getLocation(), diag::note_declared_at);
1739           return true;
1740     } else {
1741       compat = true;
1742       QualType lhsType = Context.getCanonicalType(PropertyRValueType);
1743       QualType rhsType =Context.getCanonicalType(GetterType).getUnqualifiedType();
1744       if (lhsType != rhsType && lhsType->isArithmeticType())
1745         compat = false;
1746     }
1747   }
1748 
1749   if (!compat) {
1750     Diag(Loc, diag::warn_accessor_property_type_mismatch)
1751     << property->getDeclName()
1752     << GetterMethod->getSelector();
1753     Diag(GetterMethod->getLocation(), diag::note_declared_at);
1754     return true;
1755   }
1756 
1757   return false;
1758 }
1759 
1760 /// CollectImmediateProperties - This routine collects all properties in
1761 /// the class and its conforming protocols; but not those in its super class.
1762 static void
1763 CollectImmediateProperties(ObjCContainerDecl *CDecl,
1764                            ObjCContainerDecl::PropertyMap &PropMap,
1765                            ObjCContainerDecl::PropertyMap &SuperPropMap,
1766                            bool CollectClassPropsOnly = false,
1767                            bool IncludeProtocols = true) {
1768   if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(CDecl)) {
1769     for (auto *Prop : IDecl->properties()) {
1770       if (CollectClassPropsOnly && !Prop->isClassProperty())
1771         continue;
1772       PropMap[std::make_pair(Prop->getIdentifier(), Prop->isClassProperty())] =
1773           Prop;
1774     }
1775 
1776     // Collect the properties from visible extensions.
1777     for (auto *Ext : IDecl->visible_extensions())
1778       CollectImmediateProperties(Ext, PropMap, SuperPropMap,
1779                                  CollectClassPropsOnly, IncludeProtocols);
1780 
1781     if (IncludeProtocols) {
1782       // Scan through class's protocols.
1783       for (auto *PI : IDecl->all_referenced_protocols())
1784         CollectImmediateProperties(PI, PropMap, SuperPropMap,
1785                                    CollectClassPropsOnly);
1786     }
1787   }
1788   if (ObjCCategoryDecl *CATDecl = dyn_cast<ObjCCategoryDecl>(CDecl)) {
1789     for (auto *Prop : CATDecl->properties()) {
1790       if (CollectClassPropsOnly && !Prop->isClassProperty())
1791         continue;
1792       PropMap[std::make_pair(Prop->getIdentifier(), Prop->isClassProperty())] =
1793           Prop;
1794     }
1795     if (IncludeProtocols) {
1796       // Scan through class's protocols.
1797       for (auto *PI : CATDecl->protocols())
1798         CollectImmediateProperties(PI, PropMap, SuperPropMap,
1799                                    CollectClassPropsOnly);
1800     }
1801   }
1802   else if (ObjCProtocolDecl *PDecl = dyn_cast<ObjCProtocolDecl>(CDecl)) {
1803     for (auto *Prop : PDecl->properties()) {
1804       if (CollectClassPropsOnly && !Prop->isClassProperty())
1805         continue;
1806       ObjCPropertyDecl *PropertyFromSuper =
1807           SuperPropMap[std::make_pair(Prop->getIdentifier(),
1808                                       Prop->isClassProperty())];
1809       // Exclude property for protocols which conform to class's super-class,
1810       // as super-class has to implement the property.
1811       if (!PropertyFromSuper ||
1812           PropertyFromSuper->getIdentifier() != Prop->getIdentifier()) {
1813         ObjCPropertyDecl *&PropEntry =
1814             PropMap[std::make_pair(Prop->getIdentifier(),
1815                                    Prop->isClassProperty())];
1816         if (!PropEntry)
1817           PropEntry = Prop;
1818       }
1819     }
1820     // Scan through protocol's protocols.
1821     for (auto *PI : PDecl->protocols())
1822       CollectImmediateProperties(PI, PropMap, SuperPropMap,
1823                                  CollectClassPropsOnly);
1824   }
1825 }
1826 
1827 /// CollectSuperClassPropertyImplementations - This routine collects list of
1828 /// properties to be implemented in super class(s) and also coming from their
1829 /// conforming protocols.
1830 static void CollectSuperClassPropertyImplementations(ObjCInterfaceDecl *CDecl,
1831                                     ObjCInterfaceDecl::PropertyMap &PropMap) {
1832   if (ObjCInterfaceDecl *SDecl = CDecl->getSuperClass()) {
1833     ObjCInterfaceDecl::PropertyDeclOrder PO;
1834     while (SDecl) {
1835       SDecl->collectPropertiesToImplement(PropMap, PO);
1836       SDecl = SDecl->getSuperClass();
1837     }
1838   }
1839 }
1840 
1841 /// IvarBacksCurrentMethodAccessor - This routine returns 'true' if 'IV' is
1842 /// an ivar synthesized for 'Method' and 'Method' is a property accessor
1843 /// declared in class 'IFace'.
1844 bool
1845 Sema::IvarBacksCurrentMethodAccessor(ObjCInterfaceDecl *IFace,
1846                                      ObjCMethodDecl *Method, ObjCIvarDecl *IV) {
1847   if (!IV->getSynthesize())
1848     return false;
1849   ObjCMethodDecl *IMD = IFace->lookupMethod(Method->getSelector(),
1850                                             Method->isInstanceMethod());
1851   if (!IMD || !IMD->isPropertyAccessor())
1852     return false;
1853 
1854   // look up a property declaration whose one of its accessors is implemented
1855   // by this method.
1856   for (const auto *Property : IFace->instance_properties()) {
1857     if ((Property->getGetterName() == IMD->getSelector() ||
1858          Property->getSetterName() == IMD->getSelector()) &&
1859         (Property->getPropertyIvarDecl() == IV))
1860       return true;
1861   }
1862   // Also look up property declaration in class extension whose one of its
1863   // accessors is implemented by this method.
1864   for (const auto *Ext : IFace->known_extensions())
1865     for (const auto *Property : Ext->instance_properties())
1866       if ((Property->getGetterName() == IMD->getSelector() ||
1867            Property->getSetterName() == IMD->getSelector()) &&
1868           (Property->getPropertyIvarDecl() == IV))
1869         return true;
1870   return false;
1871 }
1872 
1873 static bool SuperClassImplementsProperty(ObjCInterfaceDecl *IDecl,
1874                                          ObjCPropertyDecl *Prop) {
1875   bool SuperClassImplementsGetter = false;
1876   bool SuperClassImplementsSetter = false;
1877   if (Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_readonly)
1878     SuperClassImplementsSetter = true;
1879 
1880   while (IDecl->getSuperClass()) {
1881     ObjCInterfaceDecl *SDecl = IDecl->getSuperClass();
1882     if (!SuperClassImplementsGetter && SDecl->getInstanceMethod(Prop->getGetterName()))
1883       SuperClassImplementsGetter = true;
1884 
1885     if (!SuperClassImplementsSetter && SDecl->getInstanceMethod(Prop->getSetterName()))
1886       SuperClassImplementsSetter = true;
1887     if (SuperClassImplementsGetter && SuperClassImplementsSetter)
1888       return true;
1889     IDecl = IDecl->getSuperClass();
1890   }
1891   return false;
1892 }
1893 
1894 /// Default synthesizes all properties which must be synthesized
1895 /// in class's \@implementation.
1896 void Sema::DefaultSynthesizeProperties(Scope *S, ObjCImplDecl *IMPDecl,
1897                                        ObjCInterfaceDecl *IDecl,
1898                                        SourceLocation AtEnd) {
1899   ObjCInterfaceDecl::PropertyMap PropMap;
1900   ObjCInterfaceDecl::PropertyDeclOrder PropertyOrder;
1901   IDecl->collectPropertiesToImplement(PropMap, PropertyOrder);
1902   if (PropMap.empty())
1903     return;
1904   ObjCInterfaceDecl::PropertyMap SuperPropMap;
1905   CollectSuperClassPropertyImplementations(IDecl, SuperPropMap);
1906 
1907   for (unsigned i = 0, e = PropertyOrder.size(); i != e; i++) {
1908     ObjCPropertyDecl *Prop = PropertyOrder[i];
1909     // Is there a matching property synthesize/dynamic?
1910     if (Prop->isInvalidDecl() ||
1911         Prop->isClassProperty() ||
1912         Prop->getPropertyImplementation() == ObjCPropertyDecl::Optional)
1913       continue;
1914     // Property may have been synthesized by user.
1915     if (IMPDecl->FindPropertyImplDecl(
1916             Prop->getIdentifier(), Prop->getQueryKind()))
1917       continue;
1918     ObjCMethodDecl *ImpMethod = IMPDecl->getInstanceMethod(Prop->getGetterName());
1919     if (ImpMethod && !ImpMethod->getBody()) {
1920       if (Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_readonly)
1921         continue;
1922       ImpMethod = IMPDecl->getInstanceMethod(Prop->getSetterName());
1923       if (ImpMethod && !ImpMethod->getBody())
1924         continue;
1925     }
1926     if (ObjCPropertyImplDecl *PID =
1927         IMPDecl->FindPropertyImplIvarDecl(Prop->getIdentifier())) {
1928       Diag(Prop->getLocation(), diag::warn_no_autosynthesis_shared_ivar_property)
1929         << Prop->getIdentifier();
1930       if (PID->getLocation().isValid())
1931         Diag(PID->getLocation(), diag::note_property_synthesize);
1932       continue;
1933     }
1934     ObjCPropertyDecl *PropInSuperClass =
1935         SuperPropMap[std::make_pair(Prop->getIdentifier(),
1936                                     Prop->isClassProperty())];
1937     if (ObjCProtocolDecl *Proto =
1938           dyn_cast<ObjCProtocolDecl>(Prop->getDeclContext())) {
1939       // We won't auto-synthesize properties declared in protocols.
1940       // Suppress the warning if class's superclass implements property's
1941       // getter and implements property's setter (if readwrite property).
1942       // Or, if property is going to be implemented in its super class.
1943       if (!SuperClassImplementsProperty(IDecl, Prop) && !PropInSuperClass) {
1944         Diag(IMPDecl->getLocation(),
1945              diag::warn_auto_synthesizing_protocol_property)
1946           << Prop << Proto;
1947         Diag(Prop->getLocation(), diag::note_property_declare);
1948         std::string FixIt =
1949             (Twine("@synthesize ") + Prop->getName() + ";\n\n").str();
1950         Diag(AtEnd, diag::note_add_synthesize_directive)
1951             << FixItHint::CreateInsertion(AtEnd, FixIt);
1952       }
1953       continue;
1954     }
1955     // If property to be implemented in the super class, ignore.
1956     if (PropInSuperClass) {
1957       if ((Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_readwrite) &&
1958           (PropInSuperClass->getPropertyAttributes() &
1959            ObjCPropertyDecl::OBJC_PR_readonly) &&
1960           !IMPDecl->getInstanceMethod(Prop->getSetterName()) &&
1961           !IDecl->HasUserDeclaredSetterMethod(Prop)) {
1962         Diag(Prop->getLocation(), diag::warn_no_autosynthesis_property)
1963         << Prop->getIdentifier();
1964         Diag(PropInSuperClass->getLocation(), diag::note_property_declare);
1965       }
1966       else {
1967         Diag(Prop->getLocation(), diag::warn_autosynthesis_property_in_superclass)
1968         << Prop->getIdentifier();
1969         Diag(PropInSuperClass->getLocation(), diag::note_property_declare);
1970         Diag(IMPDecl->getLocation(), diag::note_while_in_implementation);
1971       }
1972       continue;
1973     }
1974     // We use invalid SourceLocations for the synthesized ivars since they
1975     // aren't really synthesized at a particular location; they just exist.
1976     // Saying that they are located at the @implementation isn't really going
1977     // to help users.
1978     ObjCPropertyImplDecl *PIDecl = dyn_cast_or_null<ObjCPropertyImplDecl>(
1979       ActOnPropertyImplDecl(S, SourceLocation(), SourceLocation(),
1980                             true,
1981                             /* property = */ Prop->getIdentifier(),
1982                             /* ivar = */ Prop->getDefaultSynthIvarName(Context),
1983                             Prop->getLocation(), Prop->getQueryKind()));
1984     if (PIDecl && !Prop->isUnavailable()) {
1985       Diag(Prop->getLocation(), diag::warn_missing_explicit_synthesis);
1986       Diag(IMPDecl->getLocation(), diag::note_while_in_implementation);
1987     }
1988   }
1989 }
1990 
1991 void Sema::DefaultSynthesizeProperties(Scope *S, Decl *D,
1992                                        SourceLocation AtEnd) {
1993   if (!LangOpts.ObjCDefaultSynthProperties || LangOpts.ObjCRuntime.isFragile())
1994     return;
1995   ObjCImplementationDecl *IC=dyn_cast_or_null<ObjCImplementationDecl>(D);
1996   if (!IC)
1997     return;
1998   if (ObjCInterfaceDecl* IDecl = IC->getClassInterface())
1999     if (!IDecl->isObjCRequiresPropertyDefs())
2000       DefaultSynthesizeProperties(S, IC, IDecl, AtEnd);
2001 }
2002 
2003 static void DiagnoseUnimplementedAccessor(
2004     Sema &S, ObjCInterfaceDecl *PrimaryClass, Selector Method,
2005     ObjCImplDecl *IMPDecl, ObjCContainerDecl *CDecl, ObjCCategoryDecl *C,
2006     ObjCPropertyDecl *Prop,
2007     llvm::SmallPtrSet<const ObjCMethodDecl *, 8> &SMap) {
2008   // Check to see if we have a corresponding selector in SMap and with the
2009   // right method type.
2010   auto I = llvm::find_if(SMap, [&](const ObjCMethodDecl *x) {
2011     return x->getSelector() == Method &&
2012            x->isClassMethod() == Prop->isClassProperty();
2013   });
2014   // When reporting on missing property setter/getter implementation in
2015   // categories, do not report when they are declared in primary class,
2016   // class's protocol, or one of it super classes. This is because,
2017   // the class is going to implement them.
2018   if (I == SMap.end() &&
2019       (PrimaryClass == nullptr ||
2020        !PrimaryClass->lookupPropertyAccessor(Method, C,
2021                                              Prop->isClassProperty()))) {
2022     unsigned diag =
2023         isa<ObjCCategoryDecl>(CDecl)
2024             ? (Prop->isClassProperty()
2025                    ? diag::warn_impl_required_in_category_for_class_property
2026                    : diag::warn_setter_getter_impl_required_in_category)
2027             : (Prop->isClassProperty()
2028                    ? diag::warn_impl_required_for_class_property
2029                    : diag::warn_setter_getter_impl_required);
2030     S.Diag(IMPDecl->getLocation(), diag) << Prop->getDeclName() << Method;
2031     S.Diag(Prop->getLocation(), diag::note_property_declare);
2032     if (S.LangOpts.ObjCDefaultSynthProperties &&
2033         S.LangOpts.ObjCRuntime.isNonFragile())
2034       if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(CDecl))
2035         if (const ObjCInterfaceDecl *RID = ID->isObjCRequiresPropertyDefs())
2036           S.Diag(RID->getLocation(), diag::note_suppressed_class_declare);
2037   }
2038 }
2039 
2040 void Sema::DiagnoseUnimplementedProperties(Scope *S, ObjCImplDecl* IMPDecl,
2041                                            ObjCContainerDecl *CDecl,
2042                                            bool SynthesizeProperties) {
2043   ObjCContainerDecl::PropertyMap PropMap;
2044   ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(CDecl);
2045 
2046   // Since we don't synthesize class properties, we should emit diagnose even
2047   // if SynthesizeProperties is true.
2048   ObjCContainerDecl::PropertyMap NoNeedToImplPropMap;
2049   // Gather properties which need not be implemented in this class
2050   // or category.
2051   if (!IDecl)
2052     if (ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(CDecl)) {
2053       // For categories, no need to implement properties declared in
2054       // its primary class (and its super classes) if property is
2055       // declared in one of those containers.
2056       if ((IDecl = C->getClassInterface())) {
2057         ObjCInterfaceDecl::PropertyDeclOrder PO;
2058         IDecl->collectPropertiesToImplement(NoNeedToImplPropMap, PO);
2059       }
2060     }
2061   if (IDecl)
2062     CollectSuperClassPropertyImplementations(IDecl, NoNeedToImplPropMap);
2063 
2064   // When SynthesizeProperties is true, we only check class properties.
2065   CollectImmediateProperties(CDecl, PropMap, NoNeedToImplPropMap,
2066                              SynthesizeProperties/*CollectClassPropsOnly*/);
2067 
2068   // Scan the @interface to see if any of the protocols it adopts
2069   // require an explicit implementation, via attribute
2070   // 'objc_protocol_requires_explicit_implementation'.
2071   if (IDecl) {
2072     std::unique_ptr<ObjCContainerDecl::PropertyMap> LazyMap;
2073 
2074     for (auto *PDecl : IDecl->all_referenced_protocols()) {
2075       if (!PDecl->hasAttr<ObjCExplicitProtocolImplAttr>())
2076         continue;
2077       // Lazily construct a set of all the properties in the @interface
2078       // of the class, without looking at the superclass.  We cannot
2079       // use the call to CollectImmediateProperties() above as that
2080       // utilizes information from the super class's properties as well
2081       // as scans the adopted protocols.  This work only triggers for protocols
2082       // with the attribute, which is very rare, and only occurs when
2083       // analyzing the @implementation.
2084       if (!LazyMap) {
2085         ObjCContainerDecl::PropertyMap NoNeedToImplPropMap;
2086         LazyMap.reset(new ObjCContainerDecl::PropertyMap());
2087         CollectImmediateProperties(CDecl, *LazyMap, NoNeedToImplPropMap,
2088                                    /* CollectClassPropsOnly */ false,
2089                                    /* IncludeProtocols */ false);
2090       }
2091       // Add the properties of 'PDecl' to the list of properties that
2092       // need to be implemented.
2093       for (auto *PropDecl : PDecl->properties()) {
2094         if ((*LazyMap)[std::make_pair(PropDecl->getIdentifier(),
2095                                       PropDecl->isClassProperty())])
2096           continue;
2097         PropMap[std::make_pair(PropDecl->getIdentifier(),
2098                                PropDecl->isClassProperty())] = PropDecl;
2099       }
2100     }
2101   }
2102 
2103   if (PropMap.empty())
2104     return;
2105 
2106   llvm::DenseSet<ObjCPropertyDecl *> PropImplMap;
2107   for (const auto *I : IMPDecl->property_impls())
2108     PropImplMap.insert(I->getPropertyDecl());
2109 
2110   llvm::SmallPtrSet<const ObjCMethodDecl *, 8> InsMap;
2111   // Collect property accessors implemented in current implementation.
2112   for (const auto *I : IMPDecl->methods())
2113     InsMap.insert(I);
2114 
2115   ObjCCategoryDecl *C = dyn_cast<ObjCCategoryDecl>(CDecl);
2116   ObjCInterfaceDecl *PrimaryClass = nullptr;
2117   if (C && !C->IsClassExtension())
2118     if ((PrimaryClass = C->getClassInterface()))
2119       // Report unimplemented properties in the category as well.
2120       if (ObjCImplDecl *IMP = PrimaryClass->getImplementation()) {
2121         // When reporting on missing setter/getters, do not report when
2122         // setter/getter is implemented in category's primary class
2123         // implementation.
2124         for (const auto *I : IMP->methods())
2125           InsMap.insert(I);
2126       }
2127 
2128   for (ObjCContainerDecl::PropertyMap::iterator
2129        P = PropMap.begin(), E = PropMap.end(); P != E; ++P) {
2130     ObjCPropertyDecl *Prop = P->second;
2131     // Is there a matching property synthesize/dynamic?
2132     if (Prop->isInvalidDecl() ||
2133         Prop->getPropertyImplementation() == ObjCPropertyDecl::Optional ||
2134         PropImplMap.count(Prop) ||
2135         Prop->getAvailability() == AR_Unavailable)
2136       continue;
2137 
2138     // Diagnose unimplemented getters and setters.
2139     DiagnoseUnimplementedAccessor(*this,
2140           PrimaryClass, Prop->getGetterName(), IMPDecl, CDecl, C, Prop, InsMap);
2141     if (!Prop->isReadOnly())
2142       DiagnoseUnimplementedAccessor(*this,
2143                                     PrimaryClass, Prop->getSetterName(),
2144                                     IMPDecl, CDecl, C, Prop, InsMap);
2145   }
2146 }
2147 
2148 void Sema::diagnoseNullResettableSynthesizedSetters(const ObjCImplDecl *impDecl) {
2149   for (const auto *propertyImpl : impDecl->property_impls()) {
2150     const auto *property = propertyImpl->getPropertyDecl();
2151     // Warn about null_resettable properties with synthesized setters,
2152     // because the setter won't properly handle nil.
2153     if (propertyImpl->getPropertyImplementation()
2154           == ObjCPropertyImplDecl::Synthesize &&
2155         (property->getPropertyAttributes() &
2156          ObjCPropertyDecl::OBJC_PR_null_resettable) &&
2157         property->getGetterMethodDecl() &&
2158         property->getSetterMethodDecl()) {
2159       auto *getterImpl = propertyImpl->getGetterMethodDecl();
2160       auto *setterImpl = propertyImpl->getSetterMethodDecl();
2161       if ((!getterImpl || getterImpl->isSynthesizedAccessorStub()) &&
2162           (!setterImpl || setterImpl->isSynthesizedAccessorStub())) {
2163         SourceLocation loc = propertyImpl->getLocation();
2164         if (loc.isInvalid())
2165           loc = impDecl->getBeginLoc();
2166 
2167         Diag(loc, diag::warn_null_resettable_setter)
2168           << setterImpl->getSelector() << property->getDeclName();
2169       }
2170     }
2171   }
2172 }
2173 
2174 void
2175 Sema::AtomicPropertySetterGetterRules (ObjCImplDecl* IMPDecl,
2176                                        ObjCInterfaceDecl* IDecl) {
2177   // Rules apply in non-GC mode only
2178   if (getLangOpts().getGC() != LangOptions::NonGC)
2179     return;
2180   ObjCContainerDecl::PropertyMap PM;
2181   for (auto *Prop : IDecl->properties())
2182     PM[std::make_pair(Prop->getIdentifier(), Prop->isClassProperty())] = Prop;
2183   for (const auto *Ext : IDecl->known_extensions())
2184     for (auto *Prop : Ext->properties())
2185       PM[std::make_pair(Prop->getIdentifier(), Prop->isClassProperty())] = Prop;
2186 
2187   for (ObjCContainerDecl::PropertyMap::iterator I = PM.begin(), E = PM.end();
2188        I != E; ++I) {
2189     const ObjCPropertyDecl *Property = I->second;
2190     ObjCMethodDecl *GetterMethod = nullptr;
2191     ObjCMethodDecl *SetterMethod = nullptr;
2192 
2193     unsigned Attributes = Property->getPropertyAttributes();
2194     unsigned AttributesAsWritten = Property->getPropertyAttributesAsWritten();
2195 
2196     if (!(AttributesAsWritten & ObjCPropertyDecl::OBJC_PR_atomic) &&
2197         !(AttributesAsWritten & ObjCPropertyDecl::OBJC_PR_nonatomic)) {
2198       GetterMethod = Property->isClassProperty() ?
2199                      IMPDecl->getClassMethod(Property->getGetterName()) :
2200                      IMPDecl->getInstanceMethod(Property->getGetterName());
2201       SetterMethod = Property->isClassProperty() ?
2202                      IMPDecl->getClassMethod(Property->getSetterName()) :
2203                      IMPDecl->getInstanceMethod(Property->getSetterName());
2204       if (GetterMethod && GetterMethod->isSynthesizedAccessorStub())
2205         GetterMethod = nullptr;
2206       if (SetterMethod && SetterMethod->isSynthesizedAccessorStub())
2207         SetterMethod = nullptr;
2208       if (GetterMethod) {
2209         Diag(GetterMethod->getLocation(),
2210              diag::warn_default_atomic_custom_getter_setter)
2211           << Property->getIdentifier() << 0;
2212         Diag(Property->getLocation(), diag::note_property_declare);
2213       }
2214       if (SetterMethod) {
2215         Diag(SetterMethod->getLocation(),
2216              diag::warn_default_atomic_custom_getter_setter)
2217           << Property->getIdentifier() << 1;
2218         Diag(Property->getLocation(), diag::note_property_declare);
2219       }
2220     }
2221 
2222     // We only care about readwrite atomic property.
2223     if ((Attributes & ObjCPropertyDecl::OBJC_PR_nonatomic) ||
2224         !(Attributes & ObjCPropertyDecl::OBJC_PR_readwrite))
2225       continue;
2226     if (const ObjCPropertyImplDecl *PIDecl = IMPDecl->FindPropertyImplDecl(
2227             Property->getIdentifier(), Property->getQueryKind())) {
2228       if (PIDecl->getPropertyImplementation() == ObjCPropertyImplDecl::Dynamic)
2229         continue;
2230       GetterMethod = PIDecl->getGetterMethodDecl();
2231       SetterMethod = PIDecl->getSetterMethodDecl();
2232       if (GetterMethod && GetterMethod->isSynthesizedAccessorStub())
2233         GetterMethod = nullptr;
2234       if (SetterMethod && SetterMethod->isSynthesizedAccessorStub())
2235         SetterMethod = nullptr;
2236       if ((bool)GetterMethod ^ (bool)SetterMethod) {
2237         SourceLocation MethodLoc =
2238           (GetterMethod ? GetterMethod->getLocation()
2239                         : SetterMethod->getLocation());
2240         Diag(MethodLoc, diag::warn_atomic_property_rule)
2241           << Property->getIdentifier() << (GetterMethod != nullptr)
2242           << (SetterMethod != nullptr);
2243         // fixit stuff.
2244         if (Property->getLParenLoc().isValid() &&
2245             !(AttributesAsWritten & ObjCPropertyDecl::OBJC_PR_atomic)) {
2246           // @property () ... case.
2247           SourceLocation AfterLParen =
2248             getLocForEndOfToken(Property->getLParenLoc());
2249           StringRef NonatomicStr = AttributesAsWritten? "nonatomic, "
2250                                                       : "nonatomic";
2251           Diag(Property->getLocation(),
2252                diag::note_atomic_property_fixup_suggest)
2253             << FixItHint::CreateInsertion(AfterLParen, NonatomicStr);
2254         } else if (Property->getLParenLoc().isInvalid()) {
2255           //@property id etc.
2256           SourceLocation startLoc =
2257             Property->getTypeSourceInfo()->getTypeLoc().getBeginLoc();
2258           Diag(Property->getLocation(),
2259                diag::note_atomic_property_fixup_suggest)
2260             << FixItHint::CreateInsertion(startLoc, "(nonatomic) ");
2261         }
2262         else
2263           Diag(MethodLoc, diag::note_atomic_property_fixup_suggest);
2264         Diag(Property->getLocation(), diag::note_property_declare);
2265       }
2266     }
2267   }
2268 }
2269 
2270 void Sema::DiagnoseOwningPropertyGetterSynthesis(const ObjCImplementationDecl *D) {
2271   if (getLangOpts().getGC() == LangOptions::GCOnly)
2272     return;
2273 
2274   for (const auto *PID : D->property_impls()) {
2275     const ObjCPropertyDecl *PD = PID->getPropertyDecl();
2276     if (PD && !PD->hasAttr<NSReturnsNotRetainedAttr>() &&
2277         !PD->isClassProperty()) {
2278       ObjCMethodDecl *IM = PID->getGetterMethodDecl();
2279       if (IM && !IM->isSynthesizedAccessorStub())
2280         continue;
2281       ObjCMethodDecl *method = PD->getGetterMethodDecl();
2282       if (!method)
2283         continue;
2284       ObjCMethodFamily family = method->getMethodFamily();
2285       if (family == OMF_alloc || family == OMF_copy ||
2286           family == OMF_mutableCopy || family == OMF_new) {
2287         if (getLangOpts().ObjCAutoRefCount)
2288           Diag(PD->getLocation(), diag::err_cocoa_naming_owned_rule);
2289         else
2290           Diag(PD->getLocation(), diag::warn_cocoa_naming_owned_rule);
2291 
2292         // Look for a getter explicitly declared alongside the property.
2293         // If we find one, use its location for the note.
2294         SourceLocation noteLoc = PD->getLocation();
2295         SourceLocation fixItLoc;
2296         for (auto *getterRedecl : method->redecls()) {
2297           if (getterRedecl->isImplicit())
2298             continue;
2299           if (getterRedecl->getDeclContext() != PD->getDeclContext())
2300             continue;
2301           noteLoc = getterRedecl->getLocation();
2302           fixItLoc = getterRedecl->getEndLoc();
2303         }
2304 
2305         Preprocessor &PP = getPreprocessor();
2306         TokenValue tokens[] = {
2307           tok::kw___attribute, tok::l_paren, tok::l_paren,
2308           PP.getIdentifierInfo("objc_method_family"), tok::l_paren,
2309           PP.getIdentifierInfo("none"), tok::r_paren,
2310           tok::r_paren, tok::r_paren
2311         };
2312         StringRef spelling = "__attribute__((objc_method_family(none)))";
2313         StringRef macroName = PP.getLastMacroWithSpelling(noteLoc, tokens);
2314         if (!macroName.empty())
2315           spelling = macroName;
2316 
2317         auto noteDiag = Diag(noteLoc, diag::note_cocoa_naming_declare_family)
2318             << method->getDeclName() << spelling;
2319         if (fixItLoc.isValid()) {
2320           SmallString<64> fixItText(" ");
2321           fixItText += spelling;
2322           noteDiag << FixItHint::CreateInsertion(fixItLoc, fixItText);
2323         }
2324       }
2325     }
2326   }
2327 }
2328 
2329 void Sema::DiagnoseMissingDesignatedInitOverrides(
2330                                             const ObjCImplementationDecl *ImplD,
2331                                             const ObjCInterfaceDecl *IFD) {
2332   assert(IFD->hasDesignatedInitializers());
2333   const ObjCInterfaceDecl *SuperD = IFD->getSuperClass();
2334   if (!SuperD)
2335     return;
2336 
2337   SelectorSet InitSelSet;
2338   for (const auto *I : ImplD->instance_methods())
2339     if (I->getMethodFamily() == OMF_init)
2340       InitSelSet.insert(I->getSelector());
2341 
2342   SmallVector<const ObjCMethodDecl *, 8> DesignatedInits;
2343   SuperD->getDesignatedInitializers(DesignatedInits);
2344   for (SmallVector<const ObjCMethodDecl *, 8>::iterator
2345          I = DesignatedInits.begin(), E = DesignatedInits.end(); I != E; ++I) {
2346     const ObjCMethodDecl *MD = *I;
2347     if (!InitSelSet.count(MD->getSelector())) {
2348       // Don't emit a diagnostic if the overriding method in the subclass is
2349       // marked as unavailable.
2350       bool Ignore = false;
2351       if (auto *IMD = IFD->getInstanceMethod(MD->getSelector())) {
2352         Ignore = IMD->isUnavailable();
2353       } else {
2354         // Check the methods declared in the class extensions too.
2355         for (auto *Ext : IFD->visible_extensions())
2356           if (auto *IMD = Ext->getInstanceMethod(MD->getSelector())) {
2357             Ignore = IMD->isUnavailable();
2358             break;
2359           }
2360       }
2361       if (!Ignore) {
2362         Diag(ImplD->getLocation(),
2363              diag::warn_objc_implementation_missing_designated_init_override)
2364           << MD->getSelector();
2365         Diag(MD->getLocation(), diag::note_objc_designated_init_marked_here);
2366       }
2367     }
2368   }
2369 }
2370 
2371 /// AddPropertyAttrs - Propagates attributes from a property to the
2372 /// implicitly-declared getter or setter for that property.
2373 static void AddPropertyAttrs(Sema &S, ObjCMethodDecl *PropertyMethod,
2374                              ObjCPropertyDecl *Property) {
2375   // Should we just clone all attributes over?
2376   for (const auto *A : Property->attrs()) {
2377     if (isa<DeprecatedAttr>(A) ||
2378         isa<UnavailableAttr>(A) ||
2379         isa<AvailabilityAttr>(A))
2380       PropertyMethod->addAttr(A->clone(S.Context));
2381   }
2382 }
2383 
2384 /// ProcessPropertyDecl - Make sure that any user-defined setter/getter methods
2385 /// have the property type and issue diagnostics if they don't.
2386 /// Also synthesize a getter/setter method if none exist (and update the
2387 /// appropriate lookup tables.
2388 void Sema::ProcessPropertyDecl(ObjCPropertyDecl *property) {
2389   ObjCMethodDecl *GetterMethod, *SetterMethod;
2390   ObjCContainerDecl *CD = cast<ObjCContainerDecl>(property->getDeclContext());
2391   if (CD->isInvalidDecl())
2392     return;
2393 
2394   bool IsClassProperty = property->isClassProperty();
2395   GetterMethod = IsClassProperty ?
2396     CD->getClassMethod(property->getGetterName()) :
2397     CD->getInstanceMethod(property->getGetterName());
2398 
2399   // if setter or getter is not found in class extension, it might be
2400   // in the primary class.
2401   if (!GetterMethod)
2402     if (const ObjCCategoryDecl *CatDecl = dyn_cast<ObjCCategoryDecl>(CD))
2403       if (CatDecl->IsClassExtension())
2404         GetterMethod = IsClassProperty ? CatDecl->getClassInterface()->
2405                          getClassMethod(property->getGetterName()) :
2406                        CatDecl->getClassInterface()->
2407                          getInstanceMethod(property->getGetterName());
2408 
2409   SetterMethod = IsClassProperty ?
2410                  CD->getClassMethod(property->getSetterName()) :
2411                  CD->getInstanceMethod(property->getSetterName());
2412   if (!SetterMethod)
2413     if (const ObjCCategoryDecl *CatDecl = dyn_cast<ObjCCategoryDecl>(CD))
2414       if (CatDecl->IsClassExtension())
2415         SetterMethod = IsClassProperty ? CatDecl->getClassInterface()->
2416                           getClassMethod(property->getSetterName()) :
2417                        CatDecl->getClassInterface()->
2418                           getInstanceMethod(property->getSetterName());
2419   DiagnosePropertyAccessorMismatch(property, GetterMethod,
2420                                    property->getLocation());
2421 
2422   if (!property->isReadOnly() && SetterMethod) {
2423     if (Context.getCanonicalType(SetterMethod->getReturnType()) !=
2424         Context.VoidTy)
2425       Diag(SetterMethod->getLocation(), diag::err_setter_type_void);
2426     if (SetterMethod->param_size() != 1 ||
2427         !Context.hasSameUnqualifiedType(
2428           (*SetterMethod->param_begin())->getType().getNonReferenceType(),
2429           property->getType().getNonReferenceType())) {
2430       Diag(property->getLocation(),
2431            diag::warn_accessor_property_type_mismatch)
2432         << property->getDeclName()
2433         << SetterMethod->getSelector();
2434       Diag(SetterMethod->getLocation(), diag::note_declared_at);
2435     }
2436   }
2437 
2438   // Synthesize getter/setter methods if none exist.
2439   // Find the default getter and if one not found, add one.
2440   // FIXME: The synthesized property we set here is misleading. We almost always
2441   // synthesize these methods unless the user explicitly provided prototypes
2442   // (which is odd, but allowed). Sema should be typechecking that the
2443   // declarations jive in that situation (which it is not currently).
2444   if (!GetterMethod) {
2445     // No instance/class method of same name as property getter name was found.
2446     // Declare a getter method and add it to the list of methods
2447     // for this class.
2448     SourceLocation Loc = property->getLocation();
2449 
2450     // The getter returns the declared property type with all qualifiers
2451     // removed.
2452     QualType resultTy = property->getType().getAtomicUnqualifiedType();
2453 
2454     // If the property is null_resettable, the getter returns nonnull.
2455     if (property->getPropertyAttributes() &
2456         ObjCPropertyDecl::OBJC_PR_null_resettable) {
2457       QualType modifiedTy = resultTy;
2458       if (auto nullability = AttributedType::stripOuterNullability(modifiedTy)) {
2459         if (*nullability == NullabilityKind::Unspecified)
2460           resultTy = Context.getAttributedType(attr::TypeNonNull,
2461                                                modifiedTy, modifiedTy);
2462       }
2463     }
2464 
2465     GetterMethod = ObjCMethodDecl::Create(
2466         Context, Loc, Loc, property->getGetterName(), resultTy, nullptr, CD,
2467         !IsClassProperty, /*isVariadic=*/false,
2468         /*isPropertyAccessor=*/true, /*isSynthesizedAccessorStub=*/false,
2469         /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
2470         (property->getPropertyImplementation() == ObjCPropertyDecl::Optional)
2471             ? ObjCMethodDecl::Optional
2472             : ObjCMethodDecl::Required);
2473     CD->addDecl(GetterMethod);
2474 
2475     AddPropertyAttrs(*this, GetterMethod, property);
2476 
2477     if (property->isDirectProperty())
2478       GetterMethod->addAttr(ObjCDirectAttr::CreateImplicit(Context, Loc));
2479 
2480     if (property->hasAttr<NSReturnsNotRetainedAttr>())
2481       GetterMethod->addAttr(NSReturnsNotRetainedAttr::CreateImplicit(Context,
2482                                                                      Loc));
2483 
2484     if (property->hasAttr<ObjCReturnsInnerPointerAttr>())
2485       GetterMethod->addAttr(
2486         ObjCReturnsInnerPointerAttr::CreateImplicit(Context, Loc));
2487 
2488     if (const SectionAttr *SA = property->getAttr<SectionAttr>())
2489       GetterMethod->addAttr(SectionAttr::CreateImplicit(
2490           Context, SA->getName(), Loc, AttributeCommonInfo::AS_GNU,
2491           SectionAttr::GNU_section));
2492 
2493     if (getLangOpts().ObjCAutoRefCount)
2494       CheckARCMethodDecl(GetterMethod);
2495   } else
2496     // A user declared getter will be synthesize when @synthesize of
2497     // the property with the same name is seen in the @implementation
2498     GetterMethod->setPropertyAccessor(true);
2499   property->setGetterMethodDecl(GetterMethod);
2500 
2501   // Skip setter if property is read-only.
2502   if (!property->isReadOnly()) {
2503     // Find the default setter and if one not found, add one.
2504     if (!SetterMethod) {
2505       // No instance/class method of same name as property setter name was
2506       // found.
2507       // Declare a setter method and add it to the list of methods
2508       // for this class.
2509       SourceLocation Loc = property->getLocation();
2510 
2511       SetterMethod =
2512         ObjCMethodDecl::Create(Context, Loc, Loc,
2513                                property->getSetterName(), Context.VoidTy,
2514                                nullptr, CD, !IsClassProperty,
2515                                /*isVariadic=*/false,
2516                                /*isPropertyAccessor=*/true,
2517                                /*isSynthesizedAccessorStub=*/false,
2518                                /*isImplicitlyDeclared=*/true,
2519                                /*isDefined=*/false,
2520                                (property->getPropertyImplementation() ==
2521                                 ObjCPropertyDecl::Optional) ?
2522                                 ObjCMethodDecl::Optional :
2523                                 ObjCMethodDecl::Required);
2524 
2525       // Remove all qualifiers from the setter's parameter type.
2526       QualType paramTy =
2527           property->getType().getUnqualifiedType().getAtomicUnqualifiedType();
2528 
2529       // If the property is null_resettable, the setter accepts a
2530       // nullable value.
2531       if (property->getPropertyAttributes() &
2532           ObjCPropertyDecl::OBJC_PR_null_resettable) {
2533         QualType modifiedTy = paramTy;
2534         if (auto nullability = AttributedType::stripOuterNullability(modifiedTy)){
2535           if (*nullability == NullabilityKind::Unspecified)
2536             paramTy = Context.getAttributedType(attr::TypeNullable,
2537                                                 modifiedTy, modifiedTy);
2538         }
2539       }
2540 
2541       // Invent the arguments for the setter. We don't bother making a
2542       // nice name for the argument.
2543       ParmVarDecl *Argument = ParmVarDecl::Create(Context, SetterMethod,
2544                                                   Loc, Loc,
2545                                                   property->getIdentifier(),
2546                                                   paramTy,
2547                                                   /*TInfo=*/nullptr,
2548                                                   SC_None,
2549                                                   nullptr);
2550       SetterMethod->setMethodParams(Context, Argument, None);
2551 
2552       AddPropertyAttrs(*this, SetterMethod, property);
2553 
2554       if (property->isDirectProperty())
2555         SetterMethod->addAttr(ObjCDirectAttr::CreateImplicit(Context, Loc));
2556 
2557       CD->addDecl(SetterMethod);
2558       if (const SectionAttr *SA = property->getAttr<SectionAttr>())
2559         SetterMethod->addAttr(SectionAttr::CreateImplicit(
2560             Context, SA->getName(), Loc, AttributeCommonInfo::AS_GNU,
2561             SectionAttr::GNU_section));
2562       // It's possible for the user to have set a very odd custom
2563       // setter selector that causes it to have a method family.
2564       if (getLangOpts().ObjCAutoRefCount)
2565         CheckARCMethodDecl(SetterMethod);
2566     } else
2567       // A user declared setter will be synthesize when @synthesize of
2568       // the property with the same name is seen in the @implementation
2569       SetterMethod->setPropertyAccessor(true);
2570     property->setSetterMethodDecl(SetterMethod);
2571   }
2572   // Add any synthesized methods to the global pool. This allows us to
2573   // handle the following, which is supported by GCC (and part of the design).
2574   //
2575   // @interface Foo
2576   // @property double bar;
2577   // @end
2578   //
2579   // void thisIsUnfortunate() {
2580   //   id foo;
2581   //   double bar = [foo bar];
2582   // }
2583   //
2584   if (!IsClassProperty) {
2585     if (GetterMethod)
2586       AddInstanceMethodToGlobalPool(GetterMethod);
2587     if (SetterMethod)
2588       AddInstanceMethodToGlobalPool(SetterMethod);
2589   } else {
2590     if (GetterMethod)
2591       AddFactoryMethodToGlobalPool(GetterMethod);
2592     if (SetterMethod)
2593       AddFactoryMethodToGlobalPool(SetterMethod);
2594   }
2595 
2596   ObjCInterfaceDecl *CurrentClass = dyn_cast<ObjCInterfaceDecl>(CD);
2597   if (!CurrentClass) {
2598     if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(CD))
2599       CurrentClass = Cat->getClassInterface();
2600     else if (ObjCImplDecl *Impl = dyn_cast<ObjCImplDecl>(CD))
2601       CurrentClass = Impl->getClassInterface();
2602   }
2603   if (GetterMethod)
2604     CheckObjCMethodOverrides(GetterMethod, CurrentClass, Sema::RTC_Unknown);
2605   if (SetterMethod)
2606     CheckObjCMethodOverrides(SetterMethod, CurrentClass, Sema::RTC_Unknown);
2607 }
2608 
2609 void Sema::CheckObjCPropertyAttributes(Decl *PDecl,
2610                                        SourceLocation Loc,
2611                                        unsigned &Attributes,
2612                                        bool propertyInPrimaryClass) {
2613   // FIXME: Improve the reported location.
2614   if (!PDecl || PDecl->isInvalidDecl())
2615     return;
2616 
2617   if ((Attributes & ObjCDeclSpec::DQ_PR_readonly) &&
2618       (Attributes & ObjCDeclSpec::DQ_PR_readwrite))
2619     Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2620     << "readonly" << "readwrite";
2621 
2622   ObjCPropertyDecl *PropertyDecl = cast<ObjCPropertyDecl>(PDecl);
2623   QualType PropertyTy = PropertyDecl->getType();
2624 
2625   // Check for copy or retain on non-object types.
2626   if ((Attributes & (ObjCDeclSpec::DQ_PR_weak | ObjCDeclSpec::DQ_PR_copy |
2627                     ObjCDeclSpec::DQ_PR_retain | ObjCDeclSpec::DQ_PR_strong)) &&
2628       !PropertyTy->isObjCRetainableType() &&
2629       !PropertyDecl->hasAttr<ObjCNSObjectAttr>()) {
2630     Diag(Loc, diag::err_objc_property_requires_object)
2631       << (Attributes & ObjCDeclSpec::DQ_PR_weak ? "weak" :
2632           Attributes & ObjCDeclSpec::DQ_PR_copy ? "copy" : "retain (or strong)");
2633     Attributes &= ~(ObjCDeclSpec::DQ_PR_weak   | ObjCDeclSpec::DQ_PR_copy |
2634                     ObjCDeclSpec::DQ_PR_retain | ObjCDeclSpec::DQ_PR_strong);
2635     PropertyDecl->setInvalidDecl();
2636   }
2637 
2638   // Check for assign on object types.
2639   if ((Attributes & ObjCDeclSpec::DQ_PR_assign) &&
2640       !(Attributes & ObjCDeclSpec::DQ_PR_unsafe_unretained) &&
2641       PropertyTy->isObjCRetainableType() &&
2642       !PropertyTy->isObjCARCImplicitlyUnretainedType()) {
2643     Diag(Loc, diag::warn_objc_property_assign_on_object);
2644   }
2645 
2646   // Check for more than one of { assign, copy, retain }.
2647   if (Attributes & ObjCDeclSpec::DQ_PR_assign) {
2648     if (Attributes & ObjCDeclSpec::DQ_PR_copy) {
2649       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2650         << "assign" << "copy";
2651       Attributes &= ~ObjCDeclSpec::DQ_PR_copy;
2652     }
2653     if (Attributes & ObjCDeclSpec::DQ_PR_retain) {
2654       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2655         << "assign" << "retain";
2656       Attributes &= ~ObjCDeclSpec::DQ_PR_retain;
2657     }
2658     if (Attributes & ObjCDeclSpec::DQ_PR_strong) {
2659       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2660         << "assign" << "strong";
2661       Attributes &= ~ObjCDeclSpec::DQ_PR_strong;
2662     }
2663     if (getLangOpts().ObjCAutoRefCount  &&
2664         (Attributes & ObjCDeclSpec::DQ_PR_weak)) {
2665       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2666         << "assign" << "weak";
2667       Attributes &= ~ObjCDeclSpec::DQ_PR_weak;
2668     }
2669     if (PropertyDecl->hasAttr<IBOutletCollectionAttr>())
2670       Diag(Loc, diag::warn_iboutletcollection_property_assign);
2671   } else if (Attributes & ObjCDeclSpec::DQ_PR_unsafe_unretained) {
2672     if (Attributes & ObjCDeclSpec::DQ_PR_copy) {
2673       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2674         << "unsafe_unretained" << "copy";
2675       Attributes &= ~ObjCDeclSpec::DQ_PR_copy;
2676     }
2677     if (Attributes & ObjCDeclSpec::DQ_PR_retain) {
2678       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2679         << "unsafe_unretained" << "retain";
2680       Attributes &= ~ObjCDeclSpec::DQ_PR_retain;
2681     }
2682     if (Attributes & ObjCDeclSpec::DQ_PR_strong) {
2683       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2684         << "unsafe_unretained" << "strong";
2685       Attributes &= ~ObjCDeclSpec::DQ_PR_strong;
2686     }
2687     if (getLangOpts().ObjCAutoRefCount  &&
2688         (Attributes & ObjCDeclSpec::DQ_PR_weak)) {
2689       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2690         << "unsafe_unretained" << "weak";
2691       Attributes &= ~ObjCDeclSpec::DQ_PR_weak;
2692     }
2693   } else if (Attributes & ObjCDeclSpec::DQ_PR_copy) {
2694     if (Attributes & ObjCDeclSpec::DQ_PR_retain) {
2695       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2696         << "copy" << "retain";
2697       Attributes &= ~ObjCDeclSpec::DQ_PR_retain;
2698     }
2699     if (Attributes & ObjCDeclSpec::DQ_PR_strong) {
2700       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2701         << "copy" << "strong";
2702       Attributes &= ~ObjCDeclSpec::DQ_PR_strong;
2703     }
2704     if (Attributes & ObjCDeclSpec::DQ_PR_weak) {
2705       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2706         << "copy" << "weak";
2707       Attributes &= ~ObjCDeclSpec::DQ_PR_weak;
2708     }
2709   }
2710   else if ((Attributes & ObjCDeclSpec::DQ_PR_retain) &&
2711            (Attributes & ObjCDeclSpec::DQ_PR_weak)) {
2712       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2713         << "retain" << "weak";
2714       Attributes &= ~ObjCDeclSpec::DQ_PR_retain;
2715   }
2716   else if ((Attributes & ObjCDeclSpec::DQ_PR_strong) &&
2717            (Attributes & ObjCDeclSpec::DQ_PR_weak)) {
2718       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2719         << "strong" << "weak";
2720       Attributes &= ~ObjCDeclSpec::DQ_PR_weak;
2721   }
2722 
2723   if (Attributes & ObjCDeclSpec::DQ_PR_weak) {
2724     // 'weak' and 'nonnull' are mutually exclusive.
2725     if (auto nullability = PropertyTy->getNullability(Context)) {
2726       if (*nullability == NullabilityKind::NonNull)
2727         Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2728           << "nonnull" << "weak";
2729     }
2730   }
2731 
2732   if ((Attributes & ObjCDeclSpec::DQ_PR_atomic) &&
2733       (Attributes & ObjCDeclSpec::DQ_PR_nonatomic)) {
2734       Diag(Loc, diag::err_objc_property_attr_mutually_exclusive)
2735         << "atomic" << "nonatomic";
2736       Attributes &= ~ObjCDeclSpec::DQ_PR_atomic;
2737   }
2738 
2739   // Warn if user supplied no assignment attribute, property is
2740   // readwrite, and this is an object type.
2741   if (!getOwnershipRule(Attributes) && PropertyTy->isObjCRetainableType()) {
2742     if (Attributes & ObjCDeclSpec::DQ_PR_readonly) {
2743       // do nothing
2744     } else if (getLangOpts().ObjCAutoRefCount) {
2745       // With arc, @property definitions should default to strong when
2746       // not specified.
2747       PropertyDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_strong);
2748     } else if (PropertyTy->isObjCObjectPointerType()) {
2749         bool isAnyClassTy =
2750           (PropertyTy->isObjCClassType() ||
2751            PropertyTy->isObjCQualifiedClassType());
2752         // In non-gc, non-arc mode, 'Class' is treated as a 'void *' no need to
2753         // issue any warning.
2754         if (isAnyClassTy && getLangOpts().getGC() == LangOptions::NonGC)
2755           ;
2756         else if (propertyInPrimaryClass) {
2757           // Don't issue warning on property with no life time in class
2758           // extension as it is inherited from property in primary class.
2759           // Skip this warning in gc-only mode.
2760           if (getLangOpts().getGC() != LangOptions::GCOnly)
2761             Diag(Loc, diag::warn_objc_property_no_assignment_attribute);
2762 
2763           // If non-gc code warn that this is likely inappropriate.
2764           if (getLangOpts().getGC() == LangOptions::NonGC)
2765             Diag(Loc, diag::warn_objc_property_default_assign_on_object);
2766         }
2767     }
2768 
2769     // FIXME: Implement warning dependent on NSCopying being
2770     // implemented. See also:
2771     // <rdar://5168496&4855821&5607453&5096644&4947311&5698469&4947014&5168496>
2772     // (please trim this list while you are at it).
2773   }
2774 
2775   if (!(Attributes & ObjCDeclSpec::DQ_PR_copy)
2776       &&!(Attributes & ObjCDeclSpec::DQ_PR_readonly)
2777       && getLangOpts().getGC() == LangOptions::GCOnly
2778       && PropertyTy->isBlockPointerType())
2779     Diag(Loc, diag::warn_objc_property_copy_missing_on_block);
2780   else if ((Attributes & ObjCDeclSpec::DQ_PR_retain) &&
2781            !(Attributes & ObjCDeclSpec::DQ_PR_readonly) &&
2782            !(Attributes & ObjCDeclSpec::DQ_PR_strong) &&
2783            PropertyTy->isBlockPointerType())
2784       Diag(Loc, diag::warn_objc_property_retain_of_block);
2785 
2786   if ((Attributes & ObjCDeclSpec::DQ_PR_readonly) &&
2787       (Attributes & ObjCDeclSpec::DQ_PR_setter))
2788     Diag(Loc, diag::warn_objc_readonly_property_has_setter);
2789 }
2790