1 //===--- SemaExprObjC.cpp - Semantic Analysis for ObjC Expressions --------===//
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 expressions.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/DeclObjC.h"
15 #include "clang/AST/ExprObjC.h"
16 #include "clang/AST/StmtVisitor.h"
17 #include "clang/AST/TypeLoc.h"
18 #include "clang/Analysis/DomainSpecific/CocoaConventions.h"
19 #include "clang/Basic/Builtins.h"
20 #include "clang/Edit/Commit.h"
21 #include "clang/Edit/Rewriters.h"
22 #include "clang/Lex/Preprocessor.h"
23 #include "clang/Sema/Initialization.h"
24 #include "clang/Sema/Lookup.h"
25 #include "clang/Sema/Scope.h"
26 #include "clang/Sema/ScopeInfo.h"
27 #include "clang/Sema/SemaInternal.h"
28 #include "llvm/ADT/SmallString.h"
29 #include "llvm/Support/ConvertUTF.h"
30 
31 using namespace clang;
32 using namespace sema;
33 using llvm::makeArrayRef;
34 
35 ExprResult Sema::ParseObjCStringLiteral(SourceLocation *AtLocs,
36                                         ArrayRef<Expr *> Strings) {
37   // Most ObjC strings are formed out of a single piece.  However, we *can*
38   // have strings formed out of multiple @ strings with multiple pptokens in
39   // each one, e.g. @"foo" "bar" @"baz" "qux"   which need to be turned into one
40   // StringLiteral for ObjCStringLiteral to hold onto.
41   StringLiteral *S = cast<StringLiteral>(Strings[0]);
42 
43   // If we have a multi-part string, merge it all together.
44   if (Strings.size() != 1) {
45     // Concatenate objc strings.
46     SmallString<128> StrBuf;
47     SmallVector<SourceLocation, 8> StrLocs;
48 
49     for (Expr *E : Strings) {
50       S = cast<StringLiteral>(E);
51 
52       // ObjC strings can't be wide or UTF.
53       if (!S->isAscii()) {
54         Diag(S->getBeginLoc(), diag::err_cfstring_literal_not_string_constant)
55             << S->getSourceRange();
56         return true;
57       }
58 
59       // Append the string.
60       StrBuf += S->getString();
61 
62       // Get the locations of the string tokens.
63       StrLocs.append(S->tokloc_begin(), S->tokloc_end());
64     }
65 
66     // Create the aggregate string with the appropriate content and location
67     // information.
68     const ConstantArrayType *CAT = Context.getAsConstantArrayType(S->getType());
69     assert(CAT && "String literal not of constant array type!");
70     QualType StrTy = Context.getConstantArrayType(
71         CAT->getElementType(), llvm::APInt(32, StrBuf.size() + 1), nullptr,
72         CAT->getSizeModifier(), CAT->getIndexTypeCVRQualifiers());
73     S = StringLiteral::Create(Context, StrBuf, StringLiteral::Ascii,
74                               /*Pascal=*/false, StrTy, &StrLocs[0],
75                               StrLocs.size());
76   }
77 
78   return BuildObjCStringLiteral(AtLocs[0], S);
79 }
80 
81 ExprResult Sema::BuildObjCStringLiteral(SourceLocation AtLoc, StringLiteral *S){
82   // Verify that this composite string is acceptable for ObjC strings.
83   if (CheckObjCString(S))
84     return true;
85 
86   // Initialize the constant string interface lazily. This assumes
87   // the NSString interface is seen in this translation unit. Note: We
88   // don't use NSConstantString, since the runtime team considers this
89   // interface private (even though it appears in the header files).
90   QualType Ty = Context.getObjCConstantStringInterface();
91   if (!Ty.isNull()) {
92     Ty = Context.getObjCObjectPointerType(Ty);
93   } else if (getLangOpts().NoConstantCFStrings) {
94     IdentifierInfo *NSIdent=nullptr;
95     std::string StringClass(getLangOpts().ObjCConstantStringClass);
96 
97     if (StringClass.empty())
98       NSIdent = &Context.Idents.get("NSConstantString");
99     else
100       NSIdent = &Context.Idents.get(StringClass);
101 
102     NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
103                                      LookupOrdinaryName);
104     if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
105       Context.setObjCConstantStringInterface(StrIF);
106       Ty = Context.getObjCConstantStringInterface();
107       Ty = Context.getObjCObjectPointerType(Ty);
108     } else {
109       // If there is no NSConstantString interface defined then treat this
110       // as error and recover from it.
111       Diag(S->getBeginLoc(), diag::err_no_nsconstant_string_class)
112           << NSIdent << S->getSourceRange();
113       Ty = Context.getObjCIdType();
114     }
115   } else {
116     IdentifierInfo *NSIdent = NSAPIObj->getNSClassId(NSAPI::ClassId_NSString);
117     NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
118                                      LookupOrdinaryName);
119     if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
120       Context.setObjCConstantStringInterface(StrIF);
121       Ty = Context.getObjCConstantStringInterface();
122       Ty = Context.getObjCObjectPointerType(Ty);
123     } else {
124       // If there is no NSString interface defined, implicitly declare
125       // a @class NSString; and use that instead. This is to make sure
126       // type of an NSString literal is represented correctly, instead of
127       // being an 'id' type.
128       Ty = Context.getObjCNSStringType();
129       if (Ty.isNull()) {
130         ObjCInterfaceDecl *NSStringIDecl =
131           ObjCInterfaceDecl::Create (Context,
132                                      Context.getTranslationUnitDecl(),
133                                      SourceLocation(), NSIdent,
134                                      nullptr, nullptr, SourceLocation());
135         Ty = Context.getObjCInterfaceType(NSStringIDecl);
136         Context.setObjCNSStringType(Ty);
137       }
138       Ty = Context.getObjCObjectPointerType(Ty);
139     }
140   }
141 
142   return new (Context) ObjCStringLiteral(S, Ty, AtLoc);
143 }
144 
145 /// Emits an error if the given method does not exist, or if the return
146 /// type is not an Objective-C object.
147 static bool validateBoxingMethod(Sema &S, SourceLocation Loc,
148                                  const ObjCInterfaceDecl *Class,
149                                  Selector Sel, const ObjCMethodDecl *Method) {
150   if (!Method) {
151     // FIXME: Is there a better way to avoid quotes than using getName()?
152     S.Diag(Loc, diag::err_undeclared_boxing_method) << Sel << Class->getName();
153     return false;
154   }
155 
156   // Make sure the return type is reasonable.
157   QualType ReturnType = Method->getReturnType();
158   if (!ReturnType->isObjCObjectPointerType()) {
159     S.Diag(Loc, diag::err_objc_literal_method_sig)
160       << Sel;
161     S.Diag(Method->getLocation(), diag::note_objc_literal_method_return)
162       << ReturnType;
163     return false;
164   }
165 
166   return true;
167 }
168 
169 /// Maps ObjCLiteralKind to NSClassIdKindKind
170 static NSAPI::NSClassIdKindKind ClassKindFromLiteralKind(
171                                             Sema::ObjCLiteralKind LiteralKind) {
172   switch (LiteralKind) {
173     case Sema::LK_Array:
174       return NSAPI::ClassId_NSArray;
175     case Sema::LK_Dictionary:
176       return NSAPI::ClassId_NSDictionary;
177     case Sema::LK_Numeric:
178       return NSAPI::ClassId_NSNumber;
179     case Sema::LK_String:
180       return NSAPI::ClassId_NSString;
181     case Sema::LK_Boxed:
182       return NSAPI::ClassId_NSValue;
183 
184     // there is no corresponding matching
185     // between LK_None/LK_Block and NSClassIdKindKind
186     case Sema::LK_Block:
187     case Sema::LK_None:
188       break;
189   }
190   llvm_unreachable("LiteralKind can't be converted into a ClassKind");
191 }
192 
193 /// Validates ObjCInterfaceDecl availability.
194 /// ObjCInterfaceDecl, used to create ObjC literals, should be defined
195 /// if clang not in a debugger mode.
196 static bool ValidateObjCLiteralInterfaceDecl(Sema &S, ObjCInterfaceDecl *Decl,
197                                             SourceLocation Loc,
198                                             Sema::ObjCLiteralKind LiteralKind) {
199   if (!Decl) {
200     NSAPI::NSClassIdKindKind Kind = ClassKindFromLiteralKind(LiteralKind);
201     IdentifierInfo *II = S.NSAPIObj->getNSClassId(Kind);
202     S.Diag(Loc, diag::err_undeclared_objc_literal_class)
203       << II->getName() << LiteralKind;
204     return false;
205   } else if (!Decl->hasDefinition() && !S.getLangOpts().DebuggerObjCLiteral) {
206     S.Diag(Loc, diag::err_undeclared_objc_literal_class)
207       << Decl->getName() << LiteralKind;
208     S.Diag(Decl->getLocation(), diag::note_forward_class);
209     return false;
210   }
211 
212   return true;
213 }
214 
215 /// Looks up ObjCInterfaceDecl of a given NSClassIdKindKind.
216 /// Used to create ObjC literals, such as NSDictionary (@{}),
217 /// NSArray (@[]) and Boxed Expressions (@())
218 static ObjCInterfaceDecl *LookupObjCInterfaceDeclForLiteral(Sema &S,
219                                             SourceLocation Loc,
220                                             Sema::ObjCLiteralKind LiteralKind) {
221   NSAPI::NSClassIdKindKind ClassKind = ClassKindFromLiteralKind(LiteralKind);
222   IdentifierInfo *II = S.NSAPIObj->getNSClassId(ClassKind);
223   NamedDecl *IF = S.LookupSingleName(S.TUScope, II, Loc,
224                                      Sema::LookupOrdinaryName);
225   ObjCInterfaceDecl *ID = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
226   if (!ID && S.getLangOpts().DebuggerObjCLiteral) {
227     ASTContext &Context = S.Context;
228     TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
229     ID = ObjCInterfaceDecl::Create (Context, TU, SourceLocation(), II,
230                                     nullptr, nullptr, SourceLocation());
231   }
232 
233   if (!ValidateObjCLiteralInterfaceDecl(S, ID, Loc, LiteralKind)) {
234     ID = nullptr;
235   }
236 
237   return ID;
238 }
239 
240 /// Retrieve the NSNumber factory method that should be used to create
241 /// an Objective-C literal for the given type.
242 static ObjCMethodDecl *getNSNumberFactoryMethod(Sema &S, SourceLocation Loc,
243                                                 QualType NumberType,
244                                                 bool isLiteral = false,
245                                                 SourceRange R = SourceRange()) {
246   Optional<NSAPI::NSNumberLiteralMethodKind> Kind =
247       S.NSAPIObj->getNSNumberFactoryMethodKind(NumberType);
248 
249   if (!Kind) {
250     if (isLiteral) {
251       S.Diag(Loc, diag::err_invalid_nsnumber_type)
252         << NumberType << R;
253     }
254     return nullptr;
255   }
256 
257   // If we already looked up this method, we're done.
258   if (S.NSNumberLiteralMethods[*Kind])
259     return S.NSNumberLiteralMethods[*Kind];
260 
261   Selector Sel = S.NSAPIObj->getNSNumberLiteralSelector(*Kind,
262                                                         /*Instance=*/false);
263 
264   ASTContext &CX = S.Context;
265 
266   // Look up the NSNumber class, if we haven't done so already. It's cached
267   // in the Sema instance.
268   if (!S.NSNumberDecl) {
269     S.NSNumberDecl = LookupObjCInterfaceDeclForLiteral(S, Loc,
270                                                        Sema::LK_Numeric);
271     if (!S.NSNumberDecl) {
272       return nullptr;
273     }
274   }
275 
276   if (S.NSNumberPointer.isNull()) {
277     // generate the pointer to NSNumber type.
278     QualType NSNumberObject = CX.getObjCInterfaceType(S.NSNumberDecl);
279     S.NSNumberPointer = CX.getObjCObjectPointerType(NSNumberObject);
280   }
281 
282   // Look for the appropriate method within NSNumber.
283   ObjCMethodDecl *Method = S.NSNumberDecl->lookupClassMethod(Sel);
284   if (!Method && S.getLangOpts().DebuggerObjCLiteral) {
285     // create a stub definition this NSNumber factory method.
286     TypeSourceInfo *ReturnTInfo = nullptr;
287     Method =
288         ObjCMethodDecl::Create(CX, SourceLocation(), SourceLocation(), Sel,
289                                S.NSNumberPointer, ReturnTInfo, S.NSNumberDecl,
290                                /*isInstance=*/false, /*isVariadic=*/false,
291                                /*isPropertyAccessor=*/false,
292                                /*isSynthesizedAccessorStub=*/false,
293                                /*isImplicitlyDeclared=*/true,
294                                /*isDefined=*/false, ObjCMethodDecl::Required,
295                                /*HasRelatedResultType=*/false);
296     ParmVarDecl *value = ParmVarDecl::Create(S.Context, Method,
297                                              SourceLocation(), SourceLocation(),
298                                              &CX.Idents.get("value"),
299                                              NumberType, /*TInfo=*/nullptr,
300                                              SC_None, nullptr);
301     Method->setMethodParams(S.Context, value, None);
302   }
303 
304   if (!validateBoxingMethod(S, Loc, S.NSNumberDecl, Sel, Method))
305     return nullptr;
306 
307   // Note: if the parameter type is out-of-line, we'll catch it later in the
308   // implicit conversion.
309 
310   S.NSNumberLiteralMethods[*Kind] = Method;
311   return Method;
312 }
313 
314 /// BuildObjCNumericLiteral - builds an ObjCBoxedExpr AST node for the
315 /// numeric literal expression. Type of the expression will be "NSNumber *".
316 ExprResult Sema::BuildObjCNumericLiteral(SourceLocation AtLoc, Expr *Number) {
317   // Determine the type of the literal.
318   QualType NumberType = Number->getType();
319   if (CharacterLiteral *Char = dyn_cast<CharacterLiteral>(Number)) {
320     // In C, character literals have type 'int'. That's not the type we want
321     // to use to determine the Objective-c literal kind.
322     switch (Char->getKind()) {
323     case CharacterLiteral::Ascii:
324     case CharacterLiteral::UTF8:
325       NumberType = Context.CharTy;
326       break;
327 
328     case CharacterLiteral::Wide:
329       NumberType = Context.getWideCharType();
330       break;
331 
332     case CharacterLiteral::UTF16:
333       NumberType = Context.Char16Ty;
334       break;
335 
336     case CharacterLiteral::UTF32:
337       NumberType = Context.Char32Ty;
338       break;
339     }
340   }
341 
342   // Look for the appropriate method within NSNumber.
343   // Construct the literal.
344   SourceRange NR(Number->getSourceRange());
345   ObjCMethodDecl *Method = getNSNumberFactoryMethod(*this, AtLoc, NumberType,
346                                                     true, NR);
347   if (!Method)
348     return ExprError();
349 
350   // Convert the number to the type that the parameter expects.
351   ParmVarDecl *ParamDecl = Method->parameters()[0];
352   InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
353                                                                     ParamDecl);
354   ExprResult ConvertedNumber = PerformCopyInitialization(Entity,
355                                                          SourceLocation(),
356                                                          Number);
357   if (ConvertedNumber.isInvalid())
358     return ExprError();
359   Number = ConvertedNumber.get();
360 
361   // Use the effective source range of the literal, including the leading '@'.
362   return MaybeBindToTemporary(
363            new (Context) ObjCBoxedExpr(Number, NSNumberPointer, Method,
364                                        SourceRange(AtLoc, NR.getEnd())));
365 }
366 
367 ExprResult Sema::ActOnObjCBoolLiteral(SourceLocation AtLoc,
368                                       SourceLocation ValueLoc,
369                                       bool Value) {
370   ExprResult Inner;
371   if (getLangOpts().CPlusPlus) {
372     Inner = ActOnCXXBoolLiteral(ValueLoc, Value? tok::kw_true : tok::kw_false);
373   } else {
374     // C doesn't actually have a way to represent literal values of type
375     // _Bool. So, we'll use 0/1 and implicit cast to _Bool.
376     Inner = ActOnIntegerConstant(ValueLoc, Value? 1 : 0);
377     Inner = ImpCastExprToType(Inner.get(), Context.BoolTy,
378                               CK_IntegralToBoolean);
379   }
380 
381   return BuildObjCNumericLiteral(AtLoc, Inner.get());
382 }
383 
384 /// Check that the given expression is a valid element of an Objective-C
385 /// collection literal.
386 static ExprResult CheckObjCCollectionLiteralElement(Sema &S, Expr *Element,
387                                                     QualType T,
388                                                     bool ArrayLiteral = false) {
389   // If the expression is type-dependent, there's nothing for us to do.
390   if (Element->isTypeDependent())
391     return Element;
392 
393   ExprResult Result = S.CheckPlaceholderExpr(Element);
394   if (Result.isInvalid())
395     return ExprError();
396   Element = Result.get();
397 
398   // In C++, check for an implicit conversion to an Objective-C object pointer
399   // type.
400   if (S.getLangOpts().CPlusPlus && Element->getType()->isRecordType()) {
401     InitializedEntity Entity
402       = InitializedEntity::InitializeParameter(S.Context, T,
403                                                /*Consumed=*/false);
404     InitializationKind Kind = InitializationKind::CreateCopy(
405         Element->getBeginLoc(), SourceLocation());
406     InitializationSequence Seq(S, Entity, Kind, Element);
407     if (!Seq.Failed())
408       return Seq.Perform(S, Entity, Kind, Element);
409   }
410 
411   Expr *OrigElement = Element;
412 
413   // Perform lvalue-to-rvalue conversion.
414   Result = S.DefaultLvalueConversion(Element);
415   if (Result.isInvalid())
416     return ExprError();
417   Element = Result.get();
418 
419   // Make sure that we have an Objective-C pointer type or block.
420   if (!Element->getType()->isObjCObjectPointerType() &&
421       !Element->getType()->isBlockPointerType()) {
422     bool Recovered = false;
423 
424     // If this is potentially an Objective-C numeric literal, add the '@'.
425     if (isa<IntegerLiteral>(OrigElement) ||
426         isa<CharacterLiteral>(OrigElement) ||
427         isa<FloatingLiteral>(OrigElement) ||
428         isa<ObjCBoolLiteralExpr>(OrigElement) ||
429         isa<CXXBoolLiteralExpr>(OrigElement)) {
430       if (S.NSAPIObj->getNSNumberFactoryMethodKind(OrigElement->getType())) {
431         int Which = isa<CharacterLiteral>(OrigElement) ? 1
432                   : (isa<CXXBoolLiteralExpr>(OrigElement) ||
433                      isa<ObjCBoolLiteralExpr>(OrigElement)) ? 2
434                   : 3;
435 
436         S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
437             << Which << OrigElement->getSourceRange()
438             << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
439 
440         Result =
441             S.BuildObjCNumericLiteral(OrigElement->getBeginLoc(), OrigElement);
442         if (Result.isInvalid())
443           return ExprError();
444 
445         Element = Result.get();
446         Recovered = true;
447       }
448     }
449     // If this is potentially an Objective-C string literal, add the '@'.
450     else if (StringLiteral *String = dyn_cast<StringLiteral>(OrigElement)) {
451       if (String->isAscii()) {
452         S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
453             << 0 << OrigElement->getSourceRange()
454             << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
455 
456         Result = S.BuildObjCStringLiteral(OrigElement->getBeginLoc(), String);
457         if (Result.isInvalid())
458           return ExprError();
459 
460         Element = Result.get();
461         Recovered = true;
462       }
463     }
464 
465     if (!Recovered) {
466       S.Diag(Element->getBeginLoc(), diag::err_invalid_collection_element)
467           << Element->getType();
468       return ExprError();
469     }
470   }
471   if (ArrayLiteral)
472     if (ObjCStringLiteral *getString =
473           dyn_cast<ObjCStringLiteral>(OrigElement)) {
474       if (StringLiteral *SL = getString->getString()) {
475         unsigned numConcat = SL->getNumConcatenated();
476         if (numConcat > 1) {
477           // Only warn if the concatenated string doesn't come from a macro.
478           bool hasMacro = false;
479           for (unsigned i = 0; i < numConcat ; ++i)
480             if (SL->getStrTokenLoc(i).isMacroID()) {
481               hasMacro = true;
482               break;
483             }
484           if (!hasMacro)
485             S.Diag(Element->getBeginLoc(),
486                    diag::warn_concatenated_nsarray_literal)
487                 << Element->getType();
488         }
489       }
490     }
491 
492   // Make sure that the element has the type that the container factory
493   // function expects.
494   return S.PerformCopyInitialization(
495       InitializedEntity::InitializeParameter(S.Context, T,
496                                              /*Consumed=*/false),
497       Element->getBeginLoc(), Element);
498 }
499 
500 ExprResult Sema::BuildObjCBoxedExpr(SourceRange SR, Expr *ValueExpr) {
501   if (ValueExpr->isTypeDependent()) {
502     ObjCBoxedExpr *BoxedExpr =
503       new (Context) ObjCBoxedExpr(ValueExpr, Context.DependentTy, nullptr, SR);
504     return BoxedExpr;
505   }
506   ObjCMethodDecl *BoxingMethod = nullptr;
507   QualType BoxedType;
508   // Convert the expression to an RValue, so we can check for pointer types...
509   ExprResult RValue = DefaultFunctionArrayLvalueConversion(ValueExpr);
510   if (RValue.isInvalid()) {
511     return ExprError();
512   }
513   SourceLocation Loc = SR.getBegin();
514   ValueExpr = RValue.get();
515   QualType ValueType(ValueExpr->getType());
516   if (const PointerType *PT = ValueType->getAs<PointerType>()) {
517     QualType PointeeType = PT->getPointeeType();
518     if (Context.hasSameUnqualifiedType(PointeeType, Context.CharTy)) {
519 
520       if (!NSStringDecl) {
521         NSStringDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
522                                                          Sema::LK_String);
523         if (!NSStringDecl) {
524           return ExprError();
525         }
526         QualType NSStringObject = Context.getObjCInterfaceType(NSStringDecl);
527         NSStringPointer = Context.getObjCObjectPointerType(NSStringObject);
528       }
529 
530       // The boxed expression can be emitted as a compile time constant if it is
531       // a string literal whose character encoding is compatible with UTF-8.
532       if (auto *CE = dyn_cast<ImplicitCastExpr>(ValueExpr))
533         if (CE->getCastKind() == CK_ArrayToPointerDecay)
534           if (auto *SL =
535                   dyn_cast<StringLiteral>(CE->getSubExpr()->IgnoreParens())) {
536             assert((SL->isAscii() || SL->isUTF8()) &&
537                    "unexpected character encoding");
538             StringRef Str = SL->getString();
539             const llvm::UTF8 *StrBegin = Str.bytes_begin();
540             const llvm::UTF8 *StrEnd = Str.bytes_end();
541             // Check that this is a valid UTF-8 string.
542             if (llvm::isLegalUTF8String(&StrBegin, StrEnd)) {
543               BoxedType = Context.getAttributedType(
544                   AttributedType::getNullabilityAttrKind(
545                       NullabilityKind::NonNull),
546                   NSStringPointer, NSStringPointer);
547               return new (Context) ObjCBoxedExpr(CE, BoxedType, nullptr, SR);
548             }
549 
550             Diag(SL->getBeginLoc(), diag::warn_objc_boxing_invalid_utf8_string)
551                 << NSStringPointer << SL->getSourceRange();
552           }
553 
554       if (!StringWithUTF8StringMethod) {
555         IdentifierInfo *II = &Context.Idents.get("stringWithUTF8String");
556         Selector stringWithUTF8String = Context.Selectors.getUnarySelector(II);
557 
558         // Look for the appropriate method within NSString.
559         BoxingMethod = NSStringDecl->lookupClassMethod(stringWithUTF8String);
560         if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
561           // Debugger needs to work even if NSString hasn't been defined.
562           TypeSourceInfo *ReturnTInfo = nullptr;
563           ObjCMethodDecl *M = ObjCMethodDecl::Create(
564               Context, SourceLocation(), SourceLocation(), stringWithUTF8String,
565               NSStringPointer, ReturnTInfo, NSStringDecl,
566               /*isInstance=*/false, /*isVariadic=*/false,
567               /*isPropertyAccessor=*/false,
568               /*isSynthesizedAccessorStub=*/false,
569               /*isImplicitlyDeclared=*/true,
570               /*isDefined=*/false, ObjCMethodDecl::Required,
571               /*HasRelatedResultType=*/false);
572           QualType ConstCharType = Context.CharTy.withConst();
573           ParmVarDecl *value =
574             ParmVarDecl::Create(Context, M,
575                                 SourceLocation(), SourceLocation(),
576                                 &Context.Idents.get("value"),
577                                 Context.getPointerType(ConstCharType),
578                                 /*TInfo=*/nullptr,
579                                 SC_None, nullptr);
580           M->setMethodParams(Context, value, None);
581           BoxingMethod = M;
582         }
583 
584         if (!validateBoxingMethod(*this, Loc, NSStringDecl,
585                                   stringWithUTF8String, BoxingMethod))
586            return ExprError();
587 
588         StringWithUTF8StringMethod = BoxingMethod;
589       }
590 
591       BoxingMethod = StringWithUTF8StringMethod;
592       BoxedType = NSStringPointer;
593       // Transfer the nullability from method's return type.
594       Optional<NullabilityKind> Nullability =
595           BoxingMethod->getReturnType()->getNullability(Context);
596       if (Nullability)
597         BoxedType = Context.getAttributedType(
598             AttributedType::getNullabilityAttrKind(*Nullability), BoxedType,
599             BoxedType);
600     }
601   } else if (ValueType->isBuiltinType()) {
602     // The other types we support are numeric, char and BOOL/bool. We could also
603     // provide limited support for structure types, such as NSRange, NSRect, and
604     // NSSize. See NSValue (NSValueGeometryExtensions) in <Foundation/NSGeometry.h>
605     // for more details.
606 
607     // Check for a top-level character literal.
608     if (const CharacterLiteral *Char =
609         dyn_cast<CharacterLiteral>(ValueExpr->IgnoreParens())) {
610       // In C, character literals have type 'int'. That's not the type we want
611       // to use to determine the Objective-c literal kind.
612       switch (Char->getKind()) {
613       case CharacterLiteral::Ascii:
614       case CharacterLiteral::UTF8:
615         ValueType = Context.CharTy;
616         break;
617 
618       case CharacterLiteral::Wide:
619         ValueType = Context.getWideCharType();
620         break;
621 
622       case CharacterLiteral::UTF16:
623         ValueType = Context.Char16Ty;
624         break;
625 
626       case CharacterLiteral::UTF32:
627         ValueType = Context.Char32Ty;
628         break;
629       }
630     }
631     // FIXME:  Do I need to do anything special with BoolTy expressions?
632 
633     // Look for the appropriate method within NSNumber.
634     BoxingMethod = getNSNumberFactoryMethod(*this, Loc, ValueType);
635     BoxedType = NSNumberPointer;
636   } else if (const EnumType *ET = ValueType->getAs<EnumType>()) {
637     if (!ET->getDecl()->isComplete()) {
638       Diag(Loc, diag::err_objc_incomplete_boxed_expression_type)
639         << ValueType << ValueExpr->getSourceRange();
640       return ExprError();
641     }
642 
643     BoxingMethod = getNSNumberFactoryMethod(*this, Loc,
644                                             ET->getDecl()->getIntegerType());
645     BoxedType = NSNumberPointer;
646   } else if (ValueType->isObjCBoxableRecordType()) {
647     // Support for structure types, that marked as objc_boxable
648     // struct __attribute__((objc_boxable)) s { ... };
649 
650     // Look up the NSValue class, if we haven't done so already. It's cached
651     // in the Sema instance.
652     if (!NSValueDecl) {
653       NSValueDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
654                                                       Sema::LK_Boxed);
655       if (!NSValueDecl) {
656         return ExprError();
657       }
658 
659       // generate the pointer to NSValue type.
660       QualType NSValueObject = Context.getObjCInterfaceType(NSValueDecl);
661       NSValuePointer = Context.getObjCObjectPointerType(NSValueObject);
662     }
663 
664     if (!ValueWithBytesObjCTypeMethod) {
665       IdentifierInfo *II[] = {
666         &Context.Idents.get("valueWithBytes"),
667         &Context.Idents.get("objCType")
668       };
669       Selector ValueWithBytesObjCType = Context.Selectors.getSelector(2, II);
670 
671       // Look for the appropriate method within NSValue.
672       BoxingMethod = NSValueDecl->lookupClassMethod(ValueWithBytesObjCType);
673       if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
674         // Debugger needs to work even if NSValue hasn't been defined.
675         TypeSourceInfo *ReturnTInfo = nullptr;
676         ObjCMethodDecl *M = ObjCMethodDecl::Create(
677             Context, SourceLocation(), SourceLocation(), ValueWithBytesObjCType,
678             NSValuePointer, ReturnTInfo, NSValueDecl,
679             /*isInstance=*/false,
680             /*isVariadic=*/false,
681             /*isPropertyAccessor=*/false,
682             /*isSynthesizedAccessorStub=*/false,
683             /*isImplicitlyDeclared=*/true,
684             /*isDefined=*/false, ObjCMethodDecl::Required,
685             /*HasRelatedResultType=*/false);
686 
687         SmallVector<ParmVarDecl *, 2> Params;
688 
689         ParmVarDecl *bytes =
690         ParmVarDecl::Create(Context, M,
691                             SourceLocation(), SourceLocation(),
692                             &Context.Idents.get("bytes"),
693                             Context.VoidPtrTy.withConst(),
694                             /*TInfo=*/nullptr,
695                             SC_None, nullptr);
696         Params.push_back(bytes);
697 
698         QualType ConstCharType = Context.CharTy.withConst();
699         ParmVarDecl *type =
700         ParmVarDecl::Create(Context, M,
701                             SourceLocation(), SourceLocation(),
702                             &Context.Idents.get("type"),
703                             Context.getPointerType(ConstCharType),
704                             /*TInfo=*/nullptr,
705                             SC_None, nullptr);
706         Params.push_back(type);
707 
708         M->setMethodParams(Context, Params, None);
709         BoxingMethod = M;
710       }
711 
712       if (!validateBoxingMethod(*this, Loc, NSValueDecl,
713                                 ValueWithBytesObjCType, BoxingMethod))
714         return ExprError();
715 
716       ValueWithBytesObjCTypeMethod = BoxingMethod;
717     }
718 
719     if (!ValueType.isTriviallyCopyableType(Context)) {
720       Diag(Loc, diag::err_objc_non_trivially_copyable_boxed_expression_type)
721         << ValueType << ValueExpr->getSourceRange();
722       return ExprError();
723     }
724 
725     BoxingMethod = ValueWithBytesObjCTypeMethod;
726     BoxedType = NSValuePointer;
727   }
728 
729   if (!BoxingMethod) {
730     Diag(Loc, diag::err_objc_illegal_boxed_expression_type)
731       << ValueType << ValueExpr->getSourceRange();
732     return ExprError();
733   }
734 
735   DiagnoseUseOfDecl(BoxingMethod, Loc);
736 
737   ExprResult ConvertedValueExpr;
738   if (ValueType->isObjCBoxableRecordType()) {
739     InitializedEntity IE = InitializedEntity::InitializeTemporary(ValueType);
740     ConvertedValueExpr = PerformCopyInitialization(IE, ValueExpr->getExprLoc(),
741                                                    ValueExpr);
742   } else {
743     // Convert the expression to the type that the parameter requires.
744     ParmVarDecl *ParamDecl = BoxingMethod->parameters()[0];
745     InitializedEntity IE = InitializedEntity::InitializeParameter(Context,
746                                                                   ParamDecl);
747     ConvertedValueExpr = PerformCopyInitialization(IE, SourceLocation(),
748                                                    ValueExpr);
749   }
750 
751   if (ConvertedValueExpr.isInvalid())
752     return ExprError();
753   ValueExpr = ConvertedValueExpr.get();
754 
755   ObjCBoxedExpr *BoxedExpr =
756     new (Context) ObjCBoxedExpr(ValueExpr, BoxedType,
757                                       BoxingMethod, SR);
758   return MaybeBindToTemporary(BoxedExpr);
759 }
760 
761 /// Build an ObjC subscript pseudo-object expression, given that
762 /// that's supported by the runtime.
763 ExprResult Sema::BuildObjCSubscriptExpression(SourceLocation RB, Expr *BaseExpr,
764                                         Expr *IndexExpr,
765                                         ObjCMethodDecl *getterMethod,
766                                         ObjCMethodDecl *setterMethod) {
767   assert(!LangOpts.isSubscriptPointerArithmetic());
768 
769   // We can't get dependent types here; our callers should have
770   // filtered them out.
771   assert((!BaseExpr->isTypeDependent() && !IndexExpr->isTypeDependent()) &&
772          "base or index cannot have dependent type here");
773 
774   // Filter out placeholders in the index.  In theory, overloads could
775   // be preserved here, although that might not actually work correctly.
776   ExprResult Result = CheckPlaceholderExpr(IndexExpr);
777   if (Result.isInvalid())
778     return ExprError();
779   IndexExpr = Result.get();
780 
781   // Perform lvalue-to-rvalue conversion on the base.
782   Result = DefaultLvalueConversion(BaseExpr);
783   if (Result.isInvalid())
784     return ExprError();
785   BaseExpr = Result.get();
786 
787   // Build the pseudo-object expression.
788   return new (Context) ObjCSubscriptRefExpr(
789       BaseExpr, IndexExpr, Context.PseudoObjectTy, VK_LValue, OK_ObjCSubscript,
790       getterMethod, setterMethod, RB);
791 }
792 
793 ExprResult Sema::BuildObjCArrayLiteral(SourceRange SR, MultiExprArg Elements) {
794   SourceLocation Loc = SR.getBegin();
795 
796   if (!NSArrayDecl) {
797     NSArrayDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
798                                                     Sema::LK_Array);
799     if (!NSArrayDecl) {
800       return ExprError();
801     }
802   }
803 
804   // Find the arrayWithObjects:count: method, if we haven't done so already.
805   QualType IdT = Context.getObjCIdType();
806   if (!ArrayWithObjectsMethod) {
807     Selector
808       Sel = NSAPIObj->getNSArraySelector(NSAPI::NSArr_arrayWithObjectsCount);
809     ObjCMethodDecl *Method = NSArrayDecl->lookupClassMethod(Sel);
810     if (!Method && getLangOpts().DebuggerObjCLiteral) {
811       TypeSourceInfo *ReturnTInfo = nullptr;
812       Method = ObjCMethodDecl::Create(
813           Context, SourceLocation(), SourceLocation(), Sel, IdT, ReturnTInfo,
814           Context.getTranslationUnitDecl(), false /*Instance*/,
815           false /*isVariadic*/,
816           /*isPropertyAccessor=*/false, /*isSynthesizedAccessorStub=*/false,
817           /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
818           ObjCMethodDecl::Required, false);
819       SmallVector<ParmVarDecl *, 2> Params;
820       ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
821                                                  SourceLocation(),
822                                                  SourceLocation(),
823                                                  &Context.Idents.get("objects"),
824                                                  Context.getPointerType(IdT),
825                                                  /*TInfo=*/nullptr,
826                                                  SC_None, nullptr);
827       Params.push_back(objects);
828       ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
829                                              SourceLocation(),
830                                              SourceLocation(),
831                                              &Context.Idents.get("cnt"),
832                                              Context.UnsignedLongTy,
833                                              /*TInfo=*/nullptr, SC_None,
834                                              nullptr);
835       Params.push_back(cnt);
836       Method->setMethodParams(Context, Params, None);
837     }
838 
839     if (!validateBoxingMethod(*this, Loc, NSArrayDecl, Sel, Method))
840       return ExprError();
841 
842     // Dig out the type that all elements should be converted to.
843     QualType T = Method->parameters()[0]->getType();
844     const PointerType *PtrT = T->getAs<PointerType>();
845     if (!PtrT ||
846         !Context.hasSameUnqualifiedType(PtrT->getPointeeType(), IdT)) {
847       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
848         << Sel;
849       Diag(Method->parameters()[0]->getLocation(),
850            diag::note_objc_literal_method_param)
851         << 0 << T
852         << Context.getPointerType(IdT.withConst());
853       return ExprError();
854     }
855 
856     // Check that the 'count' parameter is integral.
857     if (!Method->parameters()[1]->getType()->isIntegerType()) {
858       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
859         << Sel;
860       Diag(Method->parameters()[1]->getLocation(),
861            diag::note_objc_literal_method_param)
862         << 1
863         << Method->parameters()[1]->getType()
864         << "integral";
865       return ExprError();
866     }
867 
868     // We've found a good +arrayWithObjects:count: method. Save it!
869     ArrayWithObjectsMethod = Method;
870   }
871 
872   QualType ObjectsType = ArrayWithObjectsMethod->parameters()[0]->getType();
873   QualType RequiredType = ObjectsType->castAs<PointerType>()->getPointeeType();
874 
875   // Check that each of the elements provided is valid in a collection literal,
876   // performing conversions as necessary.
877   Expr **ElementsBuffer = Elements.data();
878   for (unsigned I = 0, N = Elements.size(); I != N; ++I) {
879     ExprResult Converted = CheckObjCCollectionLiteralElement(*this,
880                                                              ElementsBuffer[I],
881                                                              RequiredType, true);
882     if (Converted.isInvalid())
883       return ExprError();
884 
885     ElementsBuffer[I] = Converted.get();
886   }
887 
888   QualType Ty
889     = Context.getObjCObjectPointerType(
890                                     Context.getObjCInterfaceType(NSArrayDecl));
891 
892   return MaybeBindToTemporary(
893            ObjCArrayLiteral::Create(Context, Elements, Ty,
894                                     ArrayWithObjectsMethod, SR));
895 }
896 
897 /// Check for duplicate keys in an ObjC dictionary literal. For instance:
898 ///   NSDictionary *nd = @{ @"foo" : @"bar", @"foo" : @"baz" };
899 static void
900 CheckObjCDictionaryLiteralDuplicateKeys(Sema &S,
901                                         ObjCDictionaryLiteral *Literal) {
902   if (Literal->isValueDependent() || Literal->isTypeDependent())
903     return;
904 
905   // NSNumber has quite relaxed equality semantics (for instance, @YES is
906   // considered equal to @1.0). For now, ignore floating points and just do a
907   // bit-width and sign agnostic integer compare.
908   struct APSIntCompare {
909     bool operator()(const llvm::APSInt &LHS, const llvm::APSInt &RHS) const {
910       return llvm::APSInt::compareValues(LHS, RHS) < 0;
911     }
912   };
913 
914   llvm::DenseMap<StringRef, SourceLocation> StringKeys;
915   std::map<llvm::APSInt, SourceLocation, APSIntCompare> IntegralKeys;
916 
917   auto checkOneKey = [&](auto &Map, const auto &Key, SourceLocation Loc) {
918     auto Pair = Map.insert({Key, Loc});
919     if (!Pair.second) {
920       S.Diag(Loc, diag::warn_nsdictionary_duplicate_key);
921       S.Diag(Pair.first->second, diag::note_nsdictionary_duplicate_key_here);
922     }
923   };
924 
925   for (unsigned Idx = 0, End = Literal->getNumElements(); Idx != End; ++Idx) {
926     Expr *Key = Literal->getKeyValueElement(Idx).Key->IgnoreParenImpCasts();
927 
928     if (auto *StrLit = dyn_cast<ObjCStringLiteral>(Key)) {
929       StringRef Bytes = StrLit->getString()->getBytes();
930       SourceLocation Loc = StrLit->getExprLoc();
931       checkOneKey(StringKeys, Bytes, Loc);
932     }
933 
934     if (auto *BE = dyn_cast<ObjCBoxedExpr>(Key)) {
935       Expr *Boxed = BE->getSubExpr();
936       SourceLocation Loc = BE->getExprLoc();
937 
938       // Check for @("foo").
939       if (auto *Str = dyn_cast<StringLiteral>(Boxed->IgnoreParenImpCasts())) {
940         checkOneKey(StringKeys, Str->getBytes(), Loc);
941         continue;
942       }
943 
944       Expr::EvalResult Result;
945       if (Boxed->EvaluateAsInt(Result, S.getASTContext(),
946                                Expr::SE_AllowSideEffects)) {
947         checkOneKey(IntegralKeys, Result.Val.getInt(), Loc);
948       }
949     }
950   }
951 }
952 
953 ExprResult Sema::BuildObjCDictionaryLiteral(SourceRange SR,
954                               MutableArrayRef<ObjCDictionaryElement> Elements) {
955   SourceLocation Loc = SR.getBegin();
956 
957   if (!NSDictionaryDecl) {
958     NSDictionaryDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
959                                                          Sema::LK_Dictionary);
960     if (!NSDictionaryDecl) {
961       return ExprError();
962     }
963   }
964 
965   // Find the dictionaryWithObjects:forKeys:count: method, if we haven't done
966   // so already.
967   QualType IdT = Context.getObjCIdType();
968   if (!DictionaryWithObjectsMethod) {
969     Selector Sel = NSAPIObj->getNSDictionarySelector(
970                                NSAPI::NSDict_dictionaryWithObjectsForKeysCount);
971     ObjCMethodDecl *Method = NSDictionaryDecl->lookupClassMethod(Sel);
972     if (!Method && getLangOpts().DebuggerObjCLiteral) {
973       Method = ObjCMethodDecl::Create(
974           Context, SourceLocation(), SourceLocation(), Sel, IdT,
975           nullptr /*TypeSourceInfo */, Context.getTranslationUnitDecl(),
976           false /*Instance*/, false /*isVariadic*/,
977           /*isPropertyAccessor=*/false,
978           /*isSynthesizedAccessorStub=*/false,
979           /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
980           ObjCMethodDecl::Required, false);
981       SmallVector<ParmVarDecl *, 3> Params;
982       ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
983                                                  SourceLocation(),
984                                                  SourceLocation(),
985                                                  &Context.Idents.get("objects"),
986                                                  Context.getPointerType(IdT),
987                                                  /*TInfo=*/nullptr, SC_None,
988                                                  nullptr);
989       Params.push_back(objects);
990       ParmVarDecl *keys = ParmVarDecl::Create(Context, Method,
991                                               SourceLocation(),
992                                               SourceLocation(),
993                                               &Context.Idents.get("keys"),
994                                               Context.getPointerType(IdT),
995                                               /*TInfo=*/nullptr, SC_None,
996                                               nullptr);
997       Params.push_back(keys);
998       ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
999                                              SourceLocation(),
1000                                              SourceLocation(),
1001                                              &Context.Idents.get("cnt"),
1002                                              Context.UnsignedLongTy,
1003                                              /*TInfo=*/nullptr, SC_None,
1004                                              nullptr);
1005       Params.push_back(cnt);
1006       Method->setMethodParams(Context, Params, None);
1007     }
1008 
1009     if (!validateBoxingMethod(*this, SR.getBegin(), NSDictionaryDecl, Sel,
1010                               Method))
1011        return ExprError();
1012 
1013     // Dig out the type that all values should be converted to.
1014     QualType ValueT = Method->parameters()[0]->getType();
1015     const PointerType *PtrValue = ValueT->getAs<PointerType>();
1016     if (!PtrValue ||
1017         !Context.hasSameUnqualifiedType(PtrValue->getPointeeType(), IdT)) {
1018       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
1019         << Sel;
1020       Diag(Method->parameters()[0]->getLocation(),
1021            diag::note_objc_literal_method_param)
1022         << 0 << ValueT
1023         << Context.getPointerType(IdT.withConst());
1024       return ExprError();
1025     }
1026 
1027     // Dig out the type that all keys should be converted to.
1028     QualType KeyT = Method->parameters()[1]->getType();
1029     const PointerType *PtrKey = KeyT->getAs<PointerType>();
1030     if (!PtrKey ||
1031         !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
1032                                         IdT)) {
1033       bool err = true;
1034       if (PtrKey) {
1035         if (QIDNSCopying.isNull()) {
1036           // key argument of selector is id<NSCopying>?
1037           if (ObjCProtocolDecl *NSCopyingPDecl =
1038               LookupProtocol(&Context.Idents.get("NSCopying"), SR.getBegin())) {
1039             ObjCProtocolDecl *PQ[] = {NSCopyingPDecl};
1040             QIDNSCopying =
1041               Context.getObjCObjectType(Context.ObjCBuiltinIdTy, { },
1042                                         llvm::makeArrayRef(
1043                                           (ObjCProtocolDecl**) PQ,
1044                                           1),
1045                                         false);
1046             QIDNSCopying = Context.getObjCObjectPointerType(QIDNSCopying);
1047           }
1048         }
1049         if (!QIDNSCopying.isNull())
1050           err = !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
1051                                                 QIDNSCopying);
1052       }
1053 
1054       if (err) {
1055         Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
1056           << Sel;
1057         Diag(Method->parameters()[1]->getLocation(),
1058              diag::note_objc_literal_method_param)
1059           << 1 << KeyT
1060           << Context.getPointerType(IdT.withConst());
1061         return ExprError();
1062       }
1063     }
1064 
1065     // Check that the 'count' parameter is integral.
1066     QualType CountType = Method->parameters()[2]->getType();
1067     if (!CountType->isIntegerType()) {
1068       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
1069         << Sel;
1070       Diag(Method->parameters()[2]->getLocation(),
1071            diag::note_objc_literal_method_param)
1072         << 2 << CountType
1073         << "integral";
1074       return ExprError();
1075     }
1076 
1077     // We've found a good +dictionaryWithObjects:keys:count: method; save it!
1078     DictionaryWithObjectsMethod = Method;
1079   }
1080 
1081   QualType ValuesT = DictionaryWithObjectsMethod->parameters()[0]->getType();
1082   QualType ValueT = ValuesT->castAs<PointerType>()->getPointeeType();
1083   QualType KeysT = DictionaryWithObjectsMethod->parameters()[1]->getType();
1084   QualType KeyT = KeysT->castAs<PointerType>()->getPointeeType();
1085 
1086   // Check that each of the keys and values provided is valid in a collection
1087   // literal, performing conversions as necessary.
1088   bool HasPackExpansions = false;
1089   for (ObjCDictionaryElement &Element : Elements) {
1090     // Check the key.
1091     ExprResult Key = CheckObjCCollectionLiteralElement(*this, Element.Key,
1092                                                        KeyT);
1093     if (Key.isInvalid())
1094       return ExprError();
1095 
1096     // Check the value.
1097     ExprResult Value
1098       = CheckObjCCollectionLiteralElement(*this, Element.Value, ValueT);
1099     if (Value.isInvalid())
1100       return ExprError();
1101 
1102     Element.Key = Key.get();
1103     Element.Value = Value.get();
1104 
1105     if (Element.EllipsisLoc.isInvalid())
1106       continue;
1107 
1108     if (!Element.Key->containsUnexpandedParameterPack() &&
1109         !Element.Value->containsUnexpandedParameterPack()) {
1110       Diag(Element.EllipsisLoc,
1111            diag::err_pack_expansion_without_parameter_packs)
1112           << SourceRange(Element.Key->getBeginLoc(),
1113                          Element.Value->getEndLoc());
1114       return ExprError();
1115     }
1116 
1117     HasPackExpansions = true;
1118   }
1119 
1120   QualType Ty = Context.getObjCObjectPointerType(
1121       Context.getObjCInterfaceType(NSDictionaryDecl));
1122 
1123   auto *Literal =
1124       ObjCDictionaryLiteral::Create(Context, Elements, HasPackExpansions, Ty,
1125                                     DictionaryWithObjectsMethod, SR);
1126   CheckObjCDictionaryLiteralDuplicateKeys(*this, Literal);
1127   return MaybeBindToTemporary(Literal);
1128 }
1129 
1130 ExprResult Sema::BuildObjCEncodeExpression(SourceLocation AtLoc,
1131                                       TypeSourceInfo *EncodedTypeInfo,
1132                                       SourceLocation RParenLoc) {
1133   QualType EncodedType = EncodedTypeInfo->getType();
1134   QualType StrTy;
1135   if (EncodedType->isDependentType())
1136     StrTy = Context.DependentTy;
1137   else {
1138     if (!EncodedType->getAsArrayTypeUnsafe() && //// Incomplete array is handled.
1139         !EncodedType->isVoidType()) // void is handled too.
1140       if (RequireCompleteType(AtLoc, EncodedType,
1141                               diag::err_incomplete_type_objc_at_encode,
1142                               EncodedTypeInfo->getTypeLoc()))
1143         return ExprError();
1144 
1145     std::string Str;
1146     QualType NotEncodedT;
1147     Context.getObjCEncodingForType(EncodedType, Str, nullptr, &NotEncodedT);
1148     if (!NotEncodedT.isNull())
1149       Diag(AtLoc, diag::warn_incomplete_encoded_type)
1150         << EncodedType << NotEncodedT;
1151 
1152     // The type of @encode is the same as the type of the corresponding string,
1153     // which is an array type.
1154     StrTy = Context.getStringLiteralArrayType(Context.CharTy, Str.size());
1155   }
1156 
1157   return new (Context) ObjCEncodeExpr(StrTy, EncodedTypeInfo, AtLoc, RParenLoc);
1158 }
1159 
1160 ExprResult Sema::ParseObjCEncodeExpression(SourceLocation AtLoc,
1161                                            SourceLocation EncodeLoc,
1162                                            SourceLocation LParenLoc,
1163                                            ParsedType ty,
1164                                            SourceLocation RParenLoc) {
1165   // FIXME: Preserve type source info ?
1166   TypeSourceInfo *TInfo;
1167   QualType EncodedType = GetTypeFromParser(ty, &TInfo);
1168   if (!TInfo)
1169     TInfo = Context.getTrivialTypeSourceInfo(EncodedType,
1170                                              getLocForEndOfToken(LParenLoc));
1171 
1172   return BuildObjCEncodeExpression(AtLoc, TInfo, RParenLoc);
1173 }
1174 
1175 static bool HelperToDiagnoseMismatchedMethodsInGlobalPool(Sema &S,
1176                                                SourceLocation AtLoc,
1177                                                SourceLocation LParenLoc,
1178                                                SourceLocation RParenLoc,
1179                                                ObjCMethodDecl *Method,
1180                                                ObjCMethodList &MethList) {
1181   ObjCMethodList *M = &MethList;
1182   bool Warned = false;
1183   for (M = M->getNext(); M; M=M->getNext()) {
1184     ObjCMethodDecl *MatchingMethodDecl = M->getMethod();
1185     if (MatchingMethodDecl == Method ||
1186         isa<ObjCImplDecl>(MatchingMethodDecl->getDeclContext()) ||
1187         MatchingMethodDecl->getSelector() != Method->getSelector())
1188       continue;
1189     if (!S.MatchTwoMethodDeclarations(Method,
1190                                       MatchingMethodDecl, Sema::MMS_loose)) {
1191       if (!Warned) {
1192         Warned = true;
1193         S.Diag(AtLoc, diag::warn_multiple_selectors)
1194           << Method->getSelector() << FixItHint::CreateInsertion(LParenLoc, "(")
1195           << FixItHint::CreateInsertion(RParenLoc, ")");
1196         S.Diag(Method->getLocation(), diag::note_method_declared_at)
1197           << Method->getDeclName();
1198       }
1199       S.Diag(MatchingMethodDecl->getLocation(), diag::note_method_declared_at)
1200         << MatchingMethodDecl->getDeclName();
1201     }
1202   }
1203   return Warned;
1204 }
1205 
1206 static void DiagnoseMismatchedSelectors(Sema &S, SourceLocation AtLoc,
1207                                         ObjCMethodDecl *Method,
1208                                         SourceLocation LParenLoc,
1209                                         SourceLocation RParenLoc,
1210                                         bool WarnMultipleSelectors) {
1211   if (!WarnMultipleSelectors ||
1212       S.Diags.isIgnored(diag::warn_multiple_selectors, SourceLocation()))
1213     return;
1214   bool Warned = false;
1215   for (Sema::GlobalMethodPool::iterator b = S.MethodPool.begin(),
1216        e = S.MethodPool.end(); b != e; b++) {
1217     // first, instance methods
1218     ObjCMethodList &InstMethList = b->second.first;
1219     if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
1220                                                       Method, InstMethList))
1221       Warned = true;
1222 
1223     // second, class methods
1224     ObjCMethodList &ClsMethList = b->second.second;
1225     if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
1226                                                       Method, ClsMethList) || Warned)
1227       return;
1228   }
1229 }
1230 
1231 static ObjCMethodDecl *LookupDirectMethodInMethodList(Sema &S, Selector Sel,
1232                                                       ObjCMethodList &MethList,
1233                                                       bool &onlyDirect,
1234                                                       bool &anyDirect) {
1235   (void)Sel;
1236   ObjCMethodList *M = &MethList;
1237   ObjCMethodDecl *DirectMethod = nullptr;
1238   for (; M; M = M->getNext()) {
1239     ObjCMethodDecl *Method = M->getMethod();
1240     if (!Method)
1241       continue;
1242     assert(Method->getSelector() == Sel && "Method with wrong selector in method list");
1243     if (Method->isDirectMethod()) {
1244       anyDirect = true;
1245       DirectMethod = Method;
1246     } else
1247       onlyDirect = false;
1248   }
1249 
1250   return DirectMethod;
1251 }
1252 
1253 // Search the global pool for (potentially) direct methods matching the given
1254 // selector. If a non-direct method is found, set \param onlyDirect to false. If
1255 // a direct method is found, set \param anyDirect to true. Returns a direct
1256 // method, if any.
1257 static ObjCMethodDecl *LookupDirectMethodInGlobalPool(Sema &S, Selector Sel,
1258                                                       bool &onlyDirect,
1259                                                       bool &anyDirect) {
1260   auto Iter = S.MethodPool.find(Sel);
1261   if (Iter == S.MethodPool.end())
1262     return nullptr;
1263 
1264   ObjCMethodDecl *DirectInstance = LookupDirectMethodInMethodList(
1265       S, Sel, Iter->second.first, onlyDirect, anyDirect);
1266   ObjCMethodDecl *DirectClass = LookupDirectMethodInMethodList(
1267       S, Sel, Iter->second.second, onlyDirect, anyDirect);
1268 
1269   return DirectInstance ? DirectInstance : DirectClass;
1270 }
1271 
1272 static ObjCMethodDecl *findMethodInCurrentClass(Sema &S, Selector Sel) {
1273   auto *CurMD = S.getCurMethodDecl();
1274   if (!CurMD)
1275     return nullptr;
1276   ObjCInterfaceDecl *IFace = CurMD->getClassInterface();
1277 
1278   // The language enforce that only one direct method is present in a given
1279   // class, so we just need to find one method in the current class to know
1280   // whether Sel is potentially direct in this context.
1281   if (ObjCMethodDecl *MD = IFace->lookupMethod(Sel, /*isInstance=*/true))
1282     return MD;
1283   if (ObjCMethodDecl *MD = IFace->lookupPrivateMethod(Sel, /*isInstance=*/true))
1284     return MD;
1285   if (ObjCMethodDecl *MD = IFace->lookupMethod(Sel, /*isInstance=*/false))
1286     return MD;
1287   if (ObjCMethodDecl *MD = IFace->lookupPrivateMethod(Sel, /*isInstance=*/false))
1288     return MD;
1289 
1290   return nullptr;
1291 }
1292 
1293 ExprResult Sema::ParseObjCSelectorExpression(Selector Sel,
1294                                              SourceLocation AtLoc,
1295                                              SourceLocation SelLoc,
1296                                              SourceLocation LParenLoc,
1297                                              SourceLocation RParenLoc,
1298                                              bool WarnMultipleSelectors) {
1299   ObjCMethodDecl *Method = LookupInstanceMethodInGlobalPool(Sel,
1300                              SourceRange(LParenLoc, RParenLoc));
1301   if (!Method)
1302     Method = LookupFactoryMethodInGlobalPool(Sel,
1303                                           SourceRange(LParenLoc, RParenLoc));
1304   if (!Method) {
1305     if (const ObjCMethodDecl *OM = SelectorsForTypoCorrection(Sel)) {
1306       Selector MatchedSel = OM->getSelector();
1307       SourceRange SelectorRange(LParenLoc.getLocWithOffset(1),
1308                                 RParenLoc.getLocWithOffset(-1));
1309       Diag(SelLoc, diag::warn_undeclared_selector_with_typo)
1310         << Sel << MatchedSel
1311         << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
1312 
1313     } else
1314         Diag(SelLoc, diag::warn_undeclared_selector) << Sel;
1315   } else {
1316     DiagnoseMismatchedSelectors(*this, AtLoc, Method, LParenLoc, RParenLoc,
1317                                 WarnMultipleSelectors);
1318 
1319     bool onlyDirect = true;
1320     bool anyDirect = false;
1321     ObjCMethodDecl *GlobalDirectMethod =
1322         LookupDirectMethodInGlobalPool(*this, Sel, onlyDirect, anyDirect);
1323 
1324     if (onlyDirect) {
1325       Diag(AtLoc, diag::err_direct_selector_expression)
1326           << Method->getSelector();
1327       Diag(Method->getLocation(), diag::note_direct_method_declared_at)
1328           << Method->getDeclName();
1329     } else if (anyDirect) {
1330       // If we saw any direct methods, see if we see a direct member of the
1331       // current class. If so, the @selector will likely be used to refer to
1332       // this direct method.
1333       ObjCMethodDecl *LikelyTargetMethod = findMethodInCurrentClass(*this, Sel);
1334       if (LikelyTargetMethod && LikelyTargetMethod->isDirectMethod()) {
1335         Diag(AtLoc, diag::warn_potentially_direct_selector_expression) << Sel;
1336         Diag(LikelyTargetMethod->getLocation(),
1337              diag::note_direct_method_declared_at)
1338             << LikelyTargetMethod->getDeclName();
1339       } else if (!LikelyTargetMethod) {
1340         // Otherwise, emit the "strict" variant of this diagnostic, unless
1341         // LikelyTargetMethod is non-direct.
1342         Diag(AtLoc, diag::warn_strict_potentially_direct_selector_expression)
1343             << Sel;
1344         Diag(GlobalDirectMethod->getLocation(),
1345              diag::note_direct_method_declared_at)
1346             << GlobalDirectMethod->getDeclName();
1347       }
1348     }
1349   }
1350 
1351   if (Method &&
1352       Method->getImplementationControl() != ObjCMethodDecl::Optional &&
1353       !getSourceManager().isInSystemHeader(Method->getLocation()))
1354     ReferencedSelectors.insert(std::make_pair(Sel, AtLoc));
1355 
1356   // In ARC, forbid the user from using @selector for
1357   // retain/release/autorelease/dealloc/retainCount.
1358   if (getLangOpts().ObjCAutoRefCount) {
1359     switch (Sel.getMethodFamily()) {
1360     case OMF_retain:
1361     case OMF_release:
1362     case OMF_autorelease:
1363     case OMF_retainCount:
1364     case OMF_dealloc:
1365       Diag(AtLoc, diag::err_arc_illegal_selector) <<
1366         Sel << SourceRange(LParenLoc, RParenLoc);
1367       break;
1368 
1369     case OMF_None:
1370     case OMF_alloc:
1371     case OMF_copy:
1372     case OMF_finalize:
1373     case OMF_init:
1374     case OMF_mutableCopy:
1375     case OMF_new:
1376     case OMF_self:
1377     case OMF_initialize:
1378     case OMF_performSelector:
1379       break;
1380     }
1381   }
1382   QualType Ty = Context.getObjCSelType();
1383   return new (Context) ObjCSelectorExpr(Ty, Sel, AtLoc, RParenLoc);
1384 }
1385 
1386 ExprResult Sema::ParseObjCProtocolExpression(IdentifierInfo *ProtocolId,
1387                                              SourceLocation AtLoc,
1388                                              SourceLocation ProtoLoc,
1389                                              SourceLocation LParenLoc,
1390                                              SourceLocation ProtoIdLoc,
1391                                              SourceLocation RParenLoc) {
1392   ObjCProtocolDecl* PDecl = LookupProtocol(ProtocolId, ProtoIdLoc);
1393   if (!PDecl) {
1394     Diag(ProtoLoc, diag::err_undeclared_protocol) << ProtocolId;
1395     return true;
1396   }
1397   if (PDecl->isNonRuntimeProtocol())
1398     Diag(ProtoLoc, diag::err_objc_non_runtime_protocol_in_protocol_expr)
1399         << PDecl;
1400   if (!PDecl->hasDefinition()) {
1401     Diag(ProtoLoc, diag::err_atprotocol_protocol) << PDecl;
1402     Diag(PDecl->getLocation(), diag::note_entity_declared_at) << PDecl;
1403   } else {
1404     PDecl = PDecl->getDefinition();
1405   }
1406 
1407   QualType Ty = Context.getObjCProtoType();
1408   if (Ty.isNull())
1409     return true;
1410   Ty = Context.getObjCObjectPointerType(Ty);
1411   return new (Context) ObjCProtocolExpr(Ty, PDecl, AtLoc, ProtoIdLoc, RParenLoc);
1412 }
1413 
1414 /// Try to capture an implicit reference to 'self'.
1415 ObjCMethodDecl *Sema::tryCaptureObjCSelf(SourceLocation Loc) {
1416   DeclContext *DC = getFunctionLevelDeclContext();
1417 
1418   // If we're not in an ObjC method, error out.  Note that, unlike the
1419   // C++ case, we don't require an instance method --- class methods
1420   // still have a 'self', and we really do still need to capture it!
1421   ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(DC);
1422   if (!method)
1423     return nullptr;
1424 
1425   tryCaptureVariable(method->getSelfDecl(), Loc);
1426 
1427   return method;
1428 }
1429 
1430 static QualType stripObjCInstanceType(ASTContext &Context, QualType T) {
1431   QualType origType = T;
1432   if (auto nullability = AttributedType::stripOuterNullability(T)) {
1433     if (T == Context.getObjCInstanceType()) {
1434       return Context.getAttributedType(
1435                AttributedType::getNullabilityAttrKind(*nullability),
1436                Context.getObjCIdType(),
1437                Context.getObjCIdType());
1438     }
1439 
1440     return origType;
1441   }
1442 
1443   if (T == Context.getObjCInstanceType())
1444     return Context.getObjCIdType();
1445 
1446   return origType;
1447 }
1448 
1449 /// Determine the result type of a message send based on the receiver type,
1450 /// method, and the kind of message send.
1451 ///
1452 /// This is the "base" result type, which will still need to be adjusted
1453 /// to account for nullability.
1454 static QualType getBaseMessageSendResultType(Sema &S,
1455                                              QualType ReceiverType,
1456                                              ObjCMethodDecl *Method,
1457                                              bool isClassMessage,
1458                                              bool isSuperMessage) {
1459   assert(Method && "Must have a method");
1460   if (!Method->hasRelatedResultType())
1461     return Method->getSendResultType(ReceiverType);
1462 
1463   ASTContext &Context = S.Context;
1464 
1465   // Local function that transfers the nullability of the method's
1466   // result type to the returned result.
1467   auto transferNullability = [&](QualType type) -> QualType {
1468     // If the method's result type has nullability, extract it.
1469     if (auto nullability = Method->getSendResultType(ReceiverType)
1470                              ->getNullability(Context)){
1471       // Strip off any outer nullability sugar from the provided type.
1472       (void)AttributedType::stripOuterNullability(type);
1473 
1474       // Form a new attributed type using the method result type's nullability.
1475       return Context.getAttributedType(
1476                AttributedType::getNullabilityAttrKind(*nullability),
1477                type,
1478                type);
1479     }
1480 
1481     return type;
1482   };
1483 
1484   // If a method has a related return type:
1485   //   - if the method found is an instance method, but the message send
1486   //     was a class message send, T is the declared return type of the method
1487   //     found
1488   if (Method->isInstanceMethod() && isClassMessage)
1489     return stripObjCInstanceType(Context,
1490                                  Method->getSendResultType(ReceiverType));
1491 
1492   //   - if the receiver is super, T is a pointer to the class of the
1493   //     enclosing method definition
1494   if (isSuperMessage) {
1495     if (ObjCMethodDecl *CurMethod = S.getCurMethodDecl())
1496       if (ObjCInterfaceDecl *Class = CurMethod->getClassInterface()) {
1497         return transferNullability(
1498                  Context.getObjCObjectPointerType(
1499                    Context.getObjCInterfaceType(Class)));
1500       }
1501   }
1502 
1503   //   - if the receiver is the name of a class U, T is a pointer to U
1504   if (ReceiverType->getAsObjCInterfaceType())
1505     return transferNullability(Context.getObjCObjectPointerType(ReceiverType));
1506   //   - if the receiver is of type Class or qualified Class type,
1507   //     T is the declared return type of the method.
1508   if (ReceiverType->isObjCClassType() ||
1509       ReceiverType->isObjCQualifiedClassType())
1510     return stripObjCInstanceType(Context,
1511                                  Method->getSendResultType(ReceiverType));
1512 
1513   //   - if the receiver is id, qualified id, Class, or qualified Class, T
1514   //     is the receiver type, otherwise
1515   //   - T is the type of the receiver expression.
1516   return transferNullability(ReceiverType);
1517 }
1518 
1519 QualType Sema::getMessageSendResultType(const Expr *Receiver,
1520                                         QualType ReceiverType,
1521                                         ObjCMethodDecl *Method,
1522                                         bool isClassMessage,
1523                                         bool isSuperMessage) {
1524   // Produce the result type.
1525   QualType resultType = getBaseMessageSendResultType(*this, ReceiverType,
1526                                                      Method,
1527                                                      isClassMessage,
1528                                                      isSuperMessage);
1529 
1530   // If this is a class message, ignore the nullability of the receiver.
1531   if (isClassMessage) {
1532     // In a class method, class messages to 'self' that return instancetype can
1533     // be typed as the current class.  We can safely do this in ARC because self
1534     // can't be reassigned, and we do it unsafely outside of ARC because in
1535     // practice people never reassign self in class methods and there's some
1536     // virtue in not being aggressively pedantic.
1537     if (Receiver && Receiver->isObjCSelfExpr()) {
1538       assert(ReceiverType->isObjCClassType() && "expected a Class self");
1539       QualType T = Method->getSendResultType(ReceiverType);
1540       AttributedType::stripOuterNullability(T);
1541       if (T == Context.getObjCInstanceType()) {
1542         const ObjCMethodDecl *MD = cast<ObjCMethodDecl>(
1543             cast<ImplicitParamDecl>(
1544                 cast<DeclRefExpr>(Receiver->IgnoreParenImpCasts())->getDecl())
1545                 ->getDeclContext());
1546         assert(MD->isClassMethod() && "expected a class method");
1547         QualType NewResultType = Context.getObjCObjectPointerType(
1548             Context.getObjCInterfaceType(MD->getClassInterface()));
1549         if (auto Nullability = resultType->getNullability(Context))
1550           NewResultType = Context.getAttributedType(
1551               AttributedType::getNullabilityAttrKind(*Nullability),
1552               NewResultType, NewResultType);
1553         return NewResultType;
1554       }
1555     }
1556     return resultType;
1557   }
1558 
1559   // There is nothing left to do if the result type cannot have a nullability
1560   // specifier.
1561   if (!resultType->canHaveNullability())
1562     return resultType;
1563 
1564   // Map the nullability of the result into a table index.
1565   unsigned receiverNullabilityIdx = 0;
1566   if (auto nullability = ReceiverType->getNullability(Context))
1567     receiverNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
1568 
1569   unsigned resultNullabilityIdx = 0;
1570   if (auto nullability = resultType->getNullability(Context))
1571     resultNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
1572 
1573   // The table of nullability mappings, indexed by the receiver's nullability
1574   // and then the result type's nullability.
1575   static const uint8_t None = 0;
1576   static const uint8_t NonNull = 1;
1577   static const uint8_t Nullable = 2;
1578   static const uint8_t Unspecified = 3;
1579   static const uint8_t nullabilityMap[4][4] = {
1580     //                  None        NonNull       Nullable    Unspecified
1581     /* None */        { None,       None,         Nullable,   None },
1582     /* NonNull */     { None,       NonNull,      Nullable,   Unspecified },
1583     /* Nullable */    { Nullable,   Nullable,     Nullable,   Nullable },
1584     /* Unspecified */ { None,       Unspecified,  Nullable,   Unspecified }
1585   };
1586 
1587   unsigned newResultNullabilityIdx
1588     = nullabilityMap[receiverNullabilityIdx][resultNullabilityIdx];
1589   if (newResultNullabilityIdx == resultNullabilityIdx)
1590     return resultType;
1591 
1592   // Strip off the existing nullability. This removes as little type sugar as
1593   // possible.
1594   do {
1595     if (auto attributed = dyn_cast<AttributedType>(resultType.getTypePtr())) {
1596       resultType = attributed->getModifiedType();
1597     } else {
1598       resultType = resultType.getDesugaredType(Context);
1599     }
1600   } while (resultType->getNullability(Context));
1601 
1602   // Add nullability back if needed.
1603   if (newResultNullabilityIdx > 0) {
1604     auto newNullability
1605       = static_cast<NullabilityKind>(newResultNullabilityIdx-1);
1606     return Context.getAttributedType(
1607              AttributedType::getNullabilityAttrKind(newNullability),
1608              resultType, resultType);
1609   }
1610 
1611   return resultType;
1612 }
1613 
1614 /// Look for an ObjC method whose result type exactly matches the given type.
1615 static const ObjCMethodDecl *
1616 findExplicitInstancetypeDeclarer(const ObjCMethodDecl *MD,
1617                                  QualType instancetype) {
1618   if (MD->getReturnType() == instancetype)
1619     return MD;
1620 
1621   // For these purposes, a method in an @implementation overrides a
1622   // declaration in the @interface.
1623   if (const ObjCImplDecl *impl =
1624         dyn_cast<ObjCImplDecl>(MD->getDeclContext())) {
1625     const ObjCContainerDecl *iface;
1626     if (const ObjCCategoryImplDecl *catImpl =
1627           dyn_cast<ObjCCategoryImplDecl>(impl)) {
1628       iface = catImpl->getCategoryDecl();
1629     } else {
1630       iface = impl->getClassInterface();
1631     }
1632 
1633     const ObjCMethodDecl *ifaceMD =
1634       iface->getMethod(MD->getSelector(), MD->isInstanceMethod());
1635     if (ifaceMD) return findExplicitInstancetypeDeclarer(ifaceMD, instancetype);
1636   }
1637 
1638   SmallVector<const ObjCMethodDecl *, 4> overrides;
1639   MD->getOverriddenMethods(overrides);
1640   for (unsigned i = 0, e = overrides.size(); i != e; ++i) {
1641     if (const ObjCMethodDecl *result =
1642           findExplicitInstancetypeDeclarer(overrides[i], instancetype))
1643       return result;
1644   }
1645 
1646   return nullptr;
1647 }
1648 
1649 void Sema::EmitRelatedResultTypeNoteForReturn(QualType destType) {
1650   // Only complain if we're in an ObjC method and the required return
1651   // type doesn't match the method's declared return type.
1652   ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(CurContext);
1653   if (!MD || !MD->hasRelatedResultType() ||
1654       Context.hasSameUnqualifiedType(destType, MD->getReturnType()))
1655     return;
1656 
1657   // Look for a method overridden by this method which explicitly uses
1658   // 'instancetype'.
1659   if (const ObjCMethodDecl *overridden =
1660         findExplicitInstancetypeDeclarer(MD, Context.getObjCInstanceType())) {
1661     SourceRange range = overridden->getReturnTypeSourceRange();
1662     SourceLocation loc = range.getBegin();
1663     if (loc.isInvalid())
1664       loc = overridden->getLocation();
1665     Diag(loc, diag::note_related_result_type_explicit)
1666       << /*current method*/ 1 << range;
1667     return;
1668   }
1669 
1670   // Otherwise, if we have an interesting method family, note that.
1671   // This should always trigger if the above didn't.
1672   if (ObjCMethodFamily family = MD->getMethodFamily())
1673     Diag(MD->getLocation(), diag::note_related_result_type_family)
1674       << /*current method*/ 1
1675       << family;
1676 }
1677 
1678 void Sema::EmitRelatedResultTypeNote(const Expr *E) {
1679   E = E->IgnoreParenImpCasts();
1680   const ObjCMessageExpr *MsgSend = dyn_cast<ObjCMessageExpr>(E);
1681   if (!MsgSend)
1682     return;
1683 
1684   const ObjCMethodDecl *Method = MsgSend->getMethodDecl();
1685   if (!Method)
1686     return;
1687 
1688   if (!Method->hasRelatedResultType())
1689     return;
1690 
1691   if (Context.hasSameUnqualifiedType(
1692           Method->getReturnType().getNonReferenceType(), MsgSend->getType()))
1693     return;
1694 
1695   if (!Context.hasSameUnqualifiedType(Method->getReturnType(),
1696                                       Context.getObjCInstanceType()))
1697     return;
1698 
1699   Diag(Method->getLocation(), diag::note_related_result_type_inferred)
1700     << Method->isInstanceMethod() << Method->getSelector()
1701     << MsgSend->getType();
1702 }
1703 
1704 bool Sema::CheckMessageArgumentTypes(
1705     const Expr *Receiver, QualType ReceiverType, MultiExprArg Args,
1706     Selector Sel, ArrayRef<SourceLocation> SelectorLocs, ObjCMethodDecl *Method,
1707     bool isClassMessage, bool isSuperMessage, SourceLocation lbrac,
1708     SourceLocation rbrac, SourceRange RecRange, QualType &ReturnType,
1709     ExprValueKind &VK) {
1710   SourceLocation SelLoc;
1711   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
1712     SelLoc = SelectorLocs.front();
1713   else
1714     SelLoc = lbrac;
1715 
1716   if (!Method) {
1717     // Apply default argument promotion as for (C99 6.5.2.2p6).
1718     for (unsigned i = 0, e = Args.size(); i != e; i++) {
1719       if (Args[i]->isTypeDependent())
1720         continue;
1721 
1722       ExprResult result;
1723       if (getLangOpts().DebuggerSupport) {
1724         QualType paramTy; // ignored
1725         result = checkUnknownAnyArg(SelLoc, Args[i], paramTy);
1726       } else {
1727         result = DefaultArgumentPromotion(Args[i]);
1728       }
1729       if (result.isInvalid())
1730         return true;
1731       Args[i] = result.get();
1732     }
1733 
1734     unsigned DiagID;
1735     if (getLangOpts().ObjCAutoRefCount)
1736       DiagID = diag::err_arc_method_not_found;
1737     else
1738       DiagID = isClassMessage ? diag::warn_class_method_not_found
1739                               : diag::warn_inst_method_not_found;
1740     if (!getLangOpts().DebuggerSupport) {
1741       const ObjCMethodDecl *OMD = SelectorsForTypoCorrection(Sel, ReceiverType);
1742       if (OMD && !OMD->isInvalidDecl()) {
1743         if (getLangOpts().ObjCAutoRefCount)
1744           DiagID = diag::err_method_not_found_with_typo;
1745         else
1746           DiagID = isClassMessage ? diag::warn_class_method_not_found_with_typo
1747                                   : diag::warn_instance_method_not_found_with_typo;
1748         Selector MatchedSel = OMD->getSelector();
1749         SourceRange SelectorRange(SelectorLocs.front(), SelectorLocs.back());
1750         if (MatchedSel.isUnarySelector())
1751           Diag(SelLoc, DiagID)
1752             << Sel<< isClassMessage << MatchedSel
1753             << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
1754         else
1755           Diag(SelLoc, DiagID) << Sel<< isClassMessage << MatchedSel;
1756       }
1757       else
1758         Diag(SelLoc, DiagID)
1759           << Sel << isClassMessage << SourceRange(SelectorLocs.front(),
1760                                                 SelectorLocs.back());
1761       // Find the class to which we are sending this message.
1762       if (auto *ObjPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
1763         if (ObjCInterfaceDecl *ThisClass = ObjPT->getInterfaceDecl()) {
1764           Diag(ThisClass->getLocation(), diag::note_receiver_class_declared);
1765           if (!RecRange.isInvalid())
1766             if (ThisClass->lookupClassMethod(Sel))
1767               Diag(RecRange.getBegin(), diag::note_receiver_expr_here)
1768                   << FixItHint::CreateReplacement(RecRange,
1769                                                   ThisClass->getNameAsString());
1770         }
1771       }
1772     }
1773 
1774     // In debuggers, we want to use __unknown_anytype for these
1775     // results so that clients can cast them.
1776     if (getLangOpts().DebuggerSupport) {
1777       ReturnType = Context.UnknownAnyTy;
1778     } else {
1779       ReturnType = Context.getObjCIdType();
1780     }
1781     VK = VK_RValue;
1782     return false;
1783   }
1784 
1785   ReturnType = getMessageSendResultType(Receiver, ReceiverType, Method,
1786                                         isClassMessage, isSuperMessage);
1787   VK = Expr::getValueKindForType(Method->getReturnType());
1788 
1789   unsigned NumNamedArgs = Sel.getNumArgs();
1790   // Method might have more arguments than selector indicates. This is due
1791   // to addition of c-style arguments in method.
1792   if (Method->param_size() > Sel.getNumArgs())
1793     NumNamedArgs = Method->param_size();
1794   // FIXME. This need be cleaned up.
1795   if (Args.size() < NumNamedArgs) {
1796     Diag(SelLoc, diag::err_typecheck_call_too_few_args)
1797       << 2 << NumNamedArgs << static_cast<unsigned>(Args.size());
1798     return false;
1799   }
1800 
1801   // Compute the set of type arguments to be substituted into each parameter
1802   // type.
1803   Optional<ArrayRef<QualType>> typeArgs
1804     = ReceiverType->getObjCSubstitutions(Method->getDeclContext());
1805   bool IsError = false;
1806   for (unsigned i = 0; i < NumNamedArgs; i++) {
1807     // We can't do any type-checking on a type-dependent argument.
1808     if (Args[i]->isTypeDependent())
1809       continue;
1810 
1811     Expr *argExpr = Args[i];
1812 
1813     ParmVarDecl *param = Method->parameters()[i];
1814     assert(argExpr && "CheckMessageArgumentTypes(): missing expression");
1815 
1816     if (param->hasAttr<NoEscapeAttr>())
1817       if (auto *BE = dyn_cast<BlockExpr>(
1818               argExpr->IgnoreParenNoopCasts(Context)))
1819         BE->getBlockDecl()->setDoesNotEscape();
1820 
1821     // Strip the unbridged-cast placeholder expression off unless it's
1822     // a consumed argument.
1823     if (argExpr->hasPlaceholderType(BuiltinType::ARCUnbridgedCast) &&
1824         !param->hasAttr<CFConsumedAttr>())
1825       argExpr = stripARCUnbridgedCast(argExpr);
1826 
1827     // If the parameter is __unknown_anytype, infer its type
1828     // from the argument.
1829     if (param->getType() == Context.UnknownAnyTy) {
1830       QualType paramType;
1831       ExprResult argE = checkUnknownAnyArg(SelLoc, argExpr, paramType);
1832       if (argE.isInvalid()) {
1833         IsError = true;
1834       } else {
1835         Args[i] = argE.get();
1836 
1837         // Update the parameter type in-place.
1838         param->setType(paramType);
1839       }
1840       continue;
1841     }
1842 
1843     QualType origParamType = param->getType();
1844     QualType paramType = param->getType();
1845     if (typeArgs)
1846       paramType = paramType.substObjCTypeArgs(
1847                     Context,
1848                     *typeArgs,
1849                     ObjCSubstitutionContext::Parameter);
1850 
1851     if (RequireCompleteType(argExpr->getSourceRange().getBegin(),
1852                             paramType,
1853                             diag::err_call_incomplete_argument, argExpr))
1854       return true;
1855 
1856     InitializedEntity Entity
1857       = InitializedEntity::InitializeParameter(Context, param, paramType);
1858     ExprResult ArgE = PerformCopyInitialization(Entity, SourceLocation(), argExpr);
1859     if (ArgE.isInvalid())
1860       IsError = true;
1861     else {
1862       Args[i] = ArgE.getAs<Expr>();
1863 
1864       // If we are type-erasing a block to a block-compatible
1865       // Objective-C pointer type, we may need to extend the lifetime
1866       // of the block object.
1867       if (typeArgs && Args[i]->isRValue() && paramType->isBlockPointerType() &&
1868           Args[i]->getType()->isBlockPointerType() &&
1869           origParamType->isObjCObjectPointerType()) {
1870         ExprResult arg = Args[i];
1871         maybeExtendBlockObject(arg);
1872         Args[i] = arg.get();
1873       }
1874     }
1875   }
1876 
1877   // Promote additional arguments to variadic methods.
1878   if (Method->isVariadic()) {
1879     for (unsigned i = NumNamedArgs, e = Args.size(); i < e; ++i) {
1880       if (Args[i]->isTypeDependent())
1881         continue;
1882 
1883       ExprResult Arg = DefaultVariadicArgumentPromotion(Args[i], VariadicMethod,
1884                                                         nullptr);
1885       IsError |= Arg.isInvalid();
1886       Args[i] = Arg.get();
1887     }
1888   } else {
1889     // Check for extra arguments to non-variadic methods.
1890     if (Args.size() != NumNamedArgs) {
1891       Diag(Args[NumNamedArgs]->getBeginLoc(),
1892            diag::err_typecheck_call_too_many_args)
1893           << 2 /*method*/ << NumNamedArgs << static_cast<unsigned>(Args.size())
1894           << Method->getSourceRange()
1895           << SourceRange(Args[NumNamedArgs]->getBeginLoc(),
1896                          Args.back()->getEndLoc());
1897     }
1898   }
1899 
1900   DiagnoseSentinelCalls(Method, SelLoc, Args);
1901 
1902   // Do additional checkings on method.
1903   IsError |= CheckObjCMethodCall(
1904       Method, SelLoc, makeArrayRef(Args.data(), Args.size()));
1905 
1906   return IsError;
1907 }
1908 
1909 bool Sema::isSelfExpr(Expr *RExpr) {
1910   // 'self' is objc 'self' in an objc method only.
1911   ObjCMethodDecl *Method =
1912       dyn_cast_or_null<ObjCMethodDecl>(CurContext->getNonClosureAncestor());
1913   return isSelfExpr(RExpr, Method);
1914 }
1915 
1916 bool Sema::isSelfExpr(Expr *receiver, const ObjCMethodDecl *method) {
1917   if (!method) return false;
1918 
1919   receiver = receiver->IgnoreParenLValueCasts();
1920   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(receiver))
1921     if (DRE->getDecl() == method->getSelfDecl())
1922       return true;
1923   return false;
1924 }
1925 
1926 /// LookupMethodInType - Look up a method in an ObjCObjectType.
1927 ObjCMethodDecl *Sema::LookupMethodInObjectType(Selector sel, QualType type,
1928                                                bool isInstance) {
1929   const ObjCObjectType *objType = type->castAs<ObjCObjectType>();
1930   if (ObjCInterfaceDecl *iface = objType->getInterface()) {
1931     // Look it up in the main interface (and categories, etc.)
1932     if (ObjCMethodDecl *method = iface->lookupMethod(sel, isInstance))
1933       return method;
1934 
1935     // Okay, look for "private" methods declared in any
1936     // @implementations we've seen.
1937     if (ObjCMethodDecl *method = iface->lookupPrivateMethod(sel, isInstance))
1938       return method;
1939   }
1940 
1941   // Check qualifiers.
1942   for (const auto *I : objType->quals())
1943     if (ObjCMethodDecl *method = I->lookupMethod(sel, isInstance))
1944       return method;
1945 
1946   return nullptr;
1947 }
1948 
1949 /// LookupMethodInQualifiedType - Lookups up a method in protocol qualifier
1950 /// list of a qualified objective pointer type.
1951 ObjCMethodDecl *Sema::LookupMethodInQualifiedType(Selector Sel,
1952                                               const ObjCObjectPointerType *OPT,
1953                                               bool Instance)
1954 {
1955   ObjCMethodDecl *MD = nullptr;
1956   for (const auto *PROTO : OPT->quals()) {
1957     if ((MD = PROTO->lookupMethod(Sel, Instance))) {
1958       return MD;
1959     }
1960   }
1961   return nullptr;
1962 }
1963 
1964 /// HandleExprPropertyRefExpr - Handle foo.bar where foo is a pointer to an
1965 /// objective C interface.  This is a property reference expression.
1966 ExprResult Sema::
1967 HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
1968                           Expr *BaseExpr, SourceLocation OpLoc,
1969                           DeclarationName MemberName,
1970                           SourceLocation MemberLoc,
1971                           SourceLocation SuperLoc, QualType SuperType,
1972                           bool Super) {
1973   const ObjCInterfaceType *IFaceT = OPT->getInterfaceType();
1974   ObjCInterfaceDecl *IFace = IFaceT->getDecl();
1975 
1976   if (!MemberName.isIdentifier()) {
1977     Diag(MemberLoc, diag::err_invalid_property_name)
1978       << MemberName << QualType(OPT, 0);
1979     return ExprError();
1980   }
1981 
1982   IdentifierInfo *Member = MemberName.getAsIdentifierInfo();
1983 
1984   SourceRange BaseRange = Super? SourceRange(SuperLoc)
1985                                : BaseExpr->getSourceRange();
1986   if (RequireCompleteType(MemberLoc, OPT->getPointeeType(),
1987                           diag::err_property_not_found_forward_class,
1988                           MemberName, BaseRange))
1989     return ExprError();
1990 
1991   if (ObjCPropertyDecl *PD = IFace->FindPropertyDeclaration(
1992           Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
1993     // Check whether we can reference this property.
1994     if (DiagnoseUseOfDecl(PD, MemberLoc))
1995       return ExprError();
1996     if (Super)
1997       return new (Context)
1998           ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
1999                               OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
2000     else
2001       return new (Context)
2002           ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
2003                               OK_ObjCProperty, MemberLoc, BaseExpr);
2004   }
2005   // Check protocols on qualified interfaces.
2006   for (const auto *I : OPT->quals())
2007     if (ObjCPropertyDecl *PD = I->FindPropertyDeclaration(
2008             Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
2009       // Check whether we can reference this property.
2010       if (DiagnoseUseOfDecl(PD, MemberLoc))
2011         return ExprError();
2012 
2013       if (Super)
2014         return new (Context) ObjCPropertyRefExpr(
2015             PD, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty, MemberLoc,
2016             SuperLoc, SuperType);
2017       else
2018         return new (Context)
2019             ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
2020                                 OK_ObjCProperty, MemberLoc, BaseExpr);
2021     }
2022   // If that failed, look for an "implicit" property by seeing if the nullary
2023   // selector is implemented.
2024 
2025   // FIXME: The logic for looking up nullary and unary selectors should be
2026   // shared with the code in ActOnInstanceMessage.
2027 
2028   Selector Sel = PP.getSelectorTable().getNullarySelector(Member);
2029   ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Sel);
2030 
2031   // May be found in property's qualified list.
2032   if (!Getter)
2033     Getter = LookupMethodInQualifiedType(Sel, OPT, true);
2034 
2035   // If this reference is in an @implementation, check for 'private' methods.
2036   if (!Getter)
2037     Getter = IFace->lookupPrivateMethod(Sel);
2038 
2039   if (Getter) {
2040     // Check if we can reference this property.
2041     if (DiagnoseUseOfDecl(Getter, MemberLoc))
2042       return ExprError();
2043   }
2044   // If we found a getter then this may be a valid dot-reference, we
2045   // will look for the matching setter, in case it is needed.
2046   Selector SetterSel =
2047     SelectorTable::constructSetterSelector(PP.getIdentifierTable(),
2048                                            PP.getSelectorTable(), Member);
2049   ObjCMethodDecl *Setter = IFace->lookupInstanceMethod(SetterSel);
2050 
2051   // May be found in property's qualified list.
2052   if (!Setter)
2053     Setter = LookupMethodInQualifiedType(SetterSel, OPT, true);
2054 
2055   if (!Setter) {
2056     // If this reference is in an @implementation, also check for 'private'
2057     // methods.
2058     Setter = IFace->lookupPrivateMethod(SetterSel);
2059   }
2060 
2061   if (Setter && DiagnoseUseOfDecl(Setter, MemberLoc))
2062     return ExprError();
2063 
2064   // Special warning if member name used in a property-dot for a setter accessor
2065   // does not use a property with same name; e.g. obj.X = ... for a property with
2066   // name 'x'.
2067   if (Setter && Setter->isImplicit() && Setter->isPropertyAccessor() &&
2068       !IFace->FindPropertyDeclaration(
2069           Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
2070       if (const ObjCPropertyDecl *PDecl = Setter->findPropertyDecl()) {
2071         // Do not warn if user is using property-dot syntax to make call to
2072         // user named setter.
2073         if (!(PDecl->getPropertyAttributes() &
2074               ObjCPropertyAttribute::kind_setter))
2075           Diag(MemberLoc,
2076                diag::warn_property_access_suggest)
2077           << MemberName << QualType(OPT, 0) << PDecl->getName()
2078           << FixItHint::CreateReplacement(MemberLoc, PDecl->getName());
2079       }
2080   }
2081 
2082   if (Getter || Setter) {
2083     if (Super)
2084       return new (Context)
2085           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
2086                               OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
2087     else
2088       return new (Context)
2089           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
2090                               OK_ObjCProperty, MemberLoc, BaseExpr);
2091 
2092   }
2093 
2094   // Attempt to correct for typos in property names.
2095   DeclFilterCCC<ObjCPropertyDecl> CCC{};
2096   if (TypoCorrection Corrected = CorrectTypo(
2097           DeclarationNameInfo(MemberName, MemberLoc), LookupOrdinaryName,
2098           nullptr, nullptr, CCC, CTK_ErrorRecovery, IFace, false, OPT)) {
2099     DeclarationName TypoResult = Corrected.getCorrection();
2100     if (TypoResult.isIdentifier() &&
2101         TypoResult.getAsIdentifierInfo() == Member) {
2102       // There is no need to try the correction if it is the same.
2103       NamedDecl *ChosenDecl =
2104         Corrected.isKeyword() ? nullptr : Corrected.getFoundDecl();
2105       if (ChosenDecl && isa<ObjCPropertyDecl>(ChosenDecl))
2106         if (cast<ObjCPropertyDecl>(ChosenDecl)->isClassProperty()) {
2107           // This is a class property, we should not use the instance to
2108           // access it.
2109           Diag(MemberLoc, diag::err_class_property_found) << MemberName
2110           << OPT->getInterfaceDecl()->getName()
2111           << FixItHint::CreateReplacement(BaseExpr->getSourceRange(),
2112                                           OPT->getInterfaceDecl()->getName());
2113           return ExprError();
2114         }
2115     } else {
2116       diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
2117                                 << MemberName << QualType(OPT, 0));
2118       return HandleExprPropertyRefExpr(OPT, BaseExpr, OpLoc,
2119                                        TypoResult, MemberLoc,
2120                                        SuperLoc, SuperType, Super);
2121     }
2122   }
2123   ObjCInterfaceDecl *ClassDeclared;
2124   if (ObjCIvarDecl *Ivar =
2125       IFace->lookupInstanceVariable(Member, ClassDeclared)) {
2126     QualType T = Ivar->getType();
2127     if (const ObjCObjectPointerType * OBJPT =
2128         T->getAsObjCInterfacePointerType()) {
2129       if (RequireCompleteType(MemberLoc, OBJPT->getPointeeType(),
2130                               diag::err_property_not_as_forward_class,
2131                               MemberName, BaseExpr))
2132         return ExprError();
2133     }
2134     Diag(MemberLoc,
2135          diag::err_ivar_access_using_property_syntax_suggest)
2136     << MemberName << QualType(OPT, 0) << Ivar->getDeclName()
2137     << FixItHint::CreateReplacement(OpLoc, "->");
2138     return ExprError();
2139   }
2140 
2141   Diag(MemberLoc, diag::err_property_not_found)
2142     << MemberName << QualType(OPT, 0);
2143   if (Setter)
2144     Diag(Setter->getLocation(), diag::note_getter_unavailable)
2145           << MemberName << BaseExpr->getSourceRange();
2146   return ExprError();
2147 }
2148 
2149 ExprResult Sema::
2150 ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
2151                           IdentifierInfo &propertyName,
2152                           SourceLocation receiverNameLoc,
2153                           SourceLocation propertyNameLoc) {
2154 
2155   IdentifierInfo *receiverNamePtr = &receiverName;
2156   ObjCInterfaceDecl *IFace = getObjCInterfaceDecl(receiverNamePtr,
2157                                                   receiverNameLoc);
2158 
2159   QualType SuperType;
2160   if (!IFace) {
2161     // If the "receiver" is 'super' in a method, handle it as an expression-like
2162     // property reference.
2163     if (receiverNamePtr->isStr("super")) {
2164       if (ObjCMethodDecl *CurMethod = tryCaptureObjCSelf(receiverNameLoc)) {
2165         if (auto classDecl = CurMethod->getClassInterface()) {
2166           SuperType = QualType(classDecl->getSuperClassType(), 0);
2167           if (CurMethod->isInstanceMethod()) {
2168             if (SuperType.isNull()) {
2169               // The current class does not have a superclass.
2170               Diag(receiverNameLoc, diag::err_root_class_cannot_use_super)
2171                 << CurMethod->getClassInterface()->getIdentifier();
2172               return ExprError();
2173             }
2174             QualType T = Context.getObjCObjectPointerType(SuperType);
2175 
2176             return HandleExprPropertyRefExpr(T->castAs<ObjCObjectPointerType>(),
2177                                              /*BaseExpr*/nullptr,
2178                                              SourceLocation()/*OpLoc*/,
2179                                              &propertyName,
2180                                              propertyNameLoc,
2181                                              receiverNameLoc, T, true);
2182           }
2183 
2184           // Otherwise, if this is a class method, try dispatching to our
2185           // superclass.
2186           IFace = CurMethod->getClassInterface()->getSuperClass();
2187         }
2188       }
2189     }
2190 
2191     if (!IFace) {
2192       Diag(receiverNameLoc, diag::err_expected_either) << tok::identifier
2193                                                        << tok::l_paren;
2194       return ExprError();
2195     }
2196   }
2197 
2198   Selector GetterSel;
2199   Selector SetterSel;
2200   if (auto PD = IFace->FindPropertyDeclaration(
2201           &propertyName, ObjCPropertyQueryKind::OBJC_PR_query_class)) {
2202     GetterSel = PD->getGetterName();
2203     SetterSel = PD->getSetterName();
2204   } else {
2205     GetterSel = PP.getSelectorTable().getNullarySelector(&propertyName);
2206     SetterSel = SelectorTable::constructSetterSelector(
2207         PP.getIdentifierTable(), PP.getSelectorTable(), &propertyName);
2208   }
2209 
2210   // Search for a declared property first.
2211   ObjCMethodDecl *Getter = IFace->lookupClassMethod(GetterSel);
2212 
2213   // If this reference is in an @implementation, check for 'private' methods.
2214   if (!Getter)
2215     Getter = IFace->lookupPrivateClassMethod(GetterSel);
2216 
2217   if (Getter) {
2218     // FIXME: refactor/share with ActOnMemberReference().
2219     // Check if we can reference this property.
2220     if (DiagnoseUseOfDecl(Getter, propertyNameLoc))
2221       return ExprError();
2222   }
2223 
2224   // Look for the matching setter, in case it is needed.
2225   ObjCMethodDecl *Setter = IFace->lookupClassMethod(SetterSel);
2226   if (!Setter) {
2227     // If this reference is in an @implementation, also check for 'private'
2228     // methods.
2229     Setter = IFace->lookupPrivateClassMethod(SetterSel);
2230   }
2231   // Look through local category implementations associated with the class.
2232   if (!Setter)
2233     Setter = IFace->getCategoryClassMethod(SetterSel);
2234 
2235   if (Setter && DiagnoseUseOfDecl(Setter, propertyNameLoc))
2236     return ExprError();
2237 
2238   if (Getter || Setter) {
2239     if (!SuperType.isNull())
2240       return new (Context)
2241           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
2242                               OK_ObjCProperty, propertyNameLoc, receiverNameLoc,
2243                               SuperType);
2244 
2245     return new (Context) ObjCPropertyRefExpr(
2246         Getter, Setter, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty,
2247         propertyNameLoc, receiverNameLoc, IFace);
2248   }
2249   return ExprError(Diag(propertyNameLoc, diag::err_property_not_found)
2250                      << &propertyName << Context.getObjCInterfaceType(IFace));
2251 }
2252 
2253 namespace {
2254 
2255 class ObjCInterfaceOrSuperCCC final : public CorrectionCandidateCallback {
2256  public:
2257   ObjCInterfaceOrSuperCCC(ObjCMethodDecl *Method) {
2258     // Determine whether "super" is acceptable in the current context.
2259     if (Method && Method->getClassInterface())
2260       WantObjCSuper = Method->getClassInterface()->getSuperClass();
2261   }
2262 
2263   bool ValidateCandidate(const TypoCorrection &candidate) override {
2264     return candidate.getCorrectionDeclAs<ObjCInterfaceDecl>() ||
2265         candidate.isKeyword("super");
2266   }
2267 
2268   std::unique_ptr<CorrectionCandidateCallback> clone() override {
2269     return std::make_unique<ObjCInterfaceOrSuperCCC>(*this);
2270   }
2271 };
2272 
2273 } // end anonymous namespace
2274 
2275 Sema::ObjCMessageKind Sema::getObjCMessageKind(Scope *S,
2276                                                IdentifierInfo *Name,
2277                                                SourceLocation NameLoc,
2278                                                bool IsSuper,
2279                                                bool HasTrailingDot,
2280                                                ParsedType &ReceiverType) {
2281   ReceiverType = nullptr;
2282 
2283   // If the identifier is "super" and there is no trailing dot, we're
2284   // messaging super. If the identifier is "super" and there is a
2285   // trailing dot, it's an instance message.
2286   if (IsSuper && S->isInObjcMethodScope())
2287     return HasTrailingDot? ObjCInstanceMessage : ObjCSuperMessage;
2288 
2289   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
2290   LookupName(Result, S);
2291 
2292   switch (Result.getResultKind()) {
2293   case LookupResult::NotFound:
2294     // Normal name lookup didn't find anything. If we're in an
2295     // Objective-C method, look for ivars. If we find one, we're done!
2296     // FIXME: This is a hack. Ivar lookup should be part of normal
2297     // lookup.
2298     if (ObjCMethodDecl *Method = getCurMethodDecl()) {
2299       if (!Method->getClassInterface()) {
2300         // Fall back: let the parser try to parse it as an instance message.
2301         return ObjCInstanceMessage;
2302       }
2303 
2304       ObjCInterfaceDecl *ClassDeclared;
2305       if (Method->getClassInterface()->lookupInstanceVariable(Name,
2306                                                               ClassDeclared))
2307         return ObjCInstanceMessage;
2308     }
2309 
2310     // Break out; we'll perform typo correction below.
2311     break;
2312 
2313   case LookupResult::NotFoundInCurrentInstantiation:
2314   case LookupResult::FoundOverloaded:
2315   case LookupResult::FoundUnresolvedValue:
2316   case LookupResult::Ambiguous:
2317     Result.suppressDiagnostics();
2318     return ObjCInstanceMessage;
2319 
2320   case LookupResult::Found: {
2321     // If the identifier is a class or not, and there is a trailing dot,
2322     // it's an instance message.
2323     if (HasTrailingDot)
2324       return ObjCInstanceMessage;
2325     // We found something. If it's a type, then we have a class
2326     // message. Otherwise, it's an instance message.
2327     NamedDecl *ND = Result.getFoundDecl();
2328     QualType T;
2329     if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(ND))
2330       T = Context.getObjCInterfaceType(Class);
2331     else if (TypeDecl *Type = dyn_cast<TypeDecl>(ND)) {
2332       T = Context.getTypeDeclType(Type);
2333       DiagnoseUseOfDecl(Type, NameLoc);
2334     }
2335     else
2336       return ObjCInstanceMessage;
2337 
2338     //  We have a class message, and T is the type we're
2339     //  messaging. Build source-location information for it.
2340     TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
2341     ReceiverType = CreateParsedType(T, TSInfo);
2342     return ObjCClassMessage;
2343   }
2344   }
2345 
2346   ObjCInterfaceOrSuperCCC CCC(getCurMethodDecl());
2347   if (TypoCorrection Corrected = CorrectTypo(
2348           Result.getLookupNameInfo(), Result.getLookupKind(), S, nullptr, CCC,
2349           CTK_ErrorRecovery, nullptr, false, nullptr, false)) {
2350     if (Corrected.isKeyword()) {
2351       // If we've found the keyword "super" (the only keyword that would be
2352       // returned by CorrectTypo), this is a send to super.
2353       diagnoseTypo(Corrected,
2354                    PDiag(diag::err_unknown_receiver_suggest) << Name);
2355       return ObjCSuperMessage;
2356     } else if (ObjCInterfaceDecl *Class =
2357                    Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
2358       // If we found a declaration, correct when it refers to an Objective-C
2359       // class.
2360       diagnoseTypo(Corrected,
2361                    PDiag(diag::err_unknown_receiver_suggest) << Name);
2362       QualType T = Context.getObjCInterfaceType(Class);
2363       TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
2364       ReceiverType = CreateParsedType(T, TSInfo);
2365       return ObjCClassMessage;
2366     }
2367   }
2368 
2369   // Fall back: let the parser try to parse it as an instance message.
2370   return ObjCInstanceMessage;
2371 }
2372 
2373 ExprResult Sema::ActOnSuperMessage(Scope *S,
2374                                    SourceLocation SuperLoc,
2375                                    Selector Sel,
2376                                    SourceLocation LBracLoc,
2377                                    ArrayRef<SourceLocation> SelectorLocs,
2378                                    SourceLocation RBracLoc,
2379                                    MultiExprArg Args) {
2380   // Determine whether we are inside a method or not.
2381   ObjCMethodDecl *Method = tryCaptureObjCSelf(SuperLoc);
2382   if (!Method) {
2383     Diag(SuperLoc, diag::err_invalid_receiver_to_message_super);
2384     return ExprError();
2385   }
2386 
2387   ObjCInterfaceDecl *Class = Method->getClassInterface();
2388   if (!Class) {
2389     Diag(SuperLoc, diag::err_no_super_class_message)
2390       << Method->getDeclName();
2391     return ExprError();
2392   }
2393 
2394   QualType SuperTy(Class->getSuperClassType(), 0);
2395   if (SuperTy.isNull()) {
2396     // The current class does not have a superclass.
2397     Diag(SuperLoc, diag::err_root_class_cannot_use_super)
2398       << Class->getIdentifier();
2399     return ExprError();
2400   }
2401 
2402   // We are in a method whose class has a superclass, so 'super'
2403   // is acting as a keyword.
2404   if (Method->getSelector() == Sel)
2405     getCurFunction()->ObjCShouldCallSuper = false;
2406 
2407   if (Method->isInstanceMethod()) {
2408     // Since we are in an instance method, this is an instance
2409     // message to the superclass instance.
2410     SuperTy = Context.getObjCObjectPointerType(SuperTy);
2411     return BuildInstanceMessage(nullptr, SuperTy, SuperLoc,
2412                                 Sel, /*Method=*/nullptr,
2413                                 LBracLoc, SelectorLocs, RBracLoc, Args);
2414   }
2415 
2416   // Since we are in a class method, this is a class message to
2417   // the superclass.
2418   return BuildClassMessage(/*ReceiverTypeInfo=*/nullptr,
2419                            SuperTy,
2420                            SuperLoc, Sel, /*Method=*/nullptr,
2421                            LBracLoc, SelectorLocs, RBracLoc, Args);
2422 }
2423 
2424 ExprResult Sema::BuildClassMessageImplicit(QualType ReceiverType,
2425                                            bool isSuperReceiver,
2426                                            SourceLocation Loc,
2427                                            Selector Sel,
2428                                            ObjCMethodDecl *Method,
2429                                            MultiExprArg Args) {
2430   TypeSourceInfo *receiverTypeInfo = nullptr;
2431   if (!ReceiverType.isNull())
2432     receiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType);
2433 
2434   return BuildClassMessage(receiverTypeInfo, ReceiverType,
2435                           /*SuperLoc=*/isSuperReceiver ? Loc : SourceLocation(),
2436                            Sel, Method, Loc, Loc, Loc, Args,
2437                            /*isImplicit=*/true);
2438 }
2439 
2440 static void applyCocoaAPICheck(Sema &S, const ObjCMessageExpr *Msg,
2441                                unsigned DiagID,
2442                                bool (*refactor)(const ObjCMessageExpr *,
2443                                               const NSAPI &, edit::Commit &)) {
2444   SourceLocation MsgLoc = Msg->getExprLoc();
2445   if (S.Diags.isIgnored(DiagID, MsgLoc))
2446     return;
2447 
2448   SourceManager &SM = S.SourceMgr;
2449   edit::Commit ECommit(SM, S.LangOpts);
2450   if (refactor(Msg,*S.NSAPIObj, ECommit)) {
2451     auto Builder = S.Diag(MsgLoc, DiagID)
2452                    << Msg->getSelector() << Msg->getSourceRange();
2453     // FIXME: Don't emit diagnostic at all if fixits are non-commitable.
2454     if (!ECommit.isCommitable())
2455       return;
2456     for (edit::Commit::edit_iterator
2457            I = ECommit.edit_begin(), E = ECommit.edit_end(); I != E; ++I) {
2458       const edit::Commit::Edit &Edit = *I;
2459       switch (Edit.Kind) {
2460       case edit::Commit::Act_Insert:
2461         Builder.AddFixItHint(FixItHint::CreateInsertion(Edit.OrigLoc,
2462                                                         Edit.Text,
2463                                                         Edit.BeforePrev));
2464         break;
2465       case edit::Commit::Act_InsertFromRange:
2466         Builder.AddFixItHint(
2467             FixItHint::CreateInsertionFromRange(Edit.OrigLoc,
2468                                                 Edit.getInsertFromRange(SM),
2469                                                 Edit.BeforePrev));
2470         break;
2471       case edit::Commit::Act_Remove:
2472         Builder.AddFixItHint(FixItHint::CreateRemoval(Edit.getFileRange(SM)));
2473         break;
2474       }
2475     }
2476   }
2477 }
2478 
2479 static void checkCocoaAPI(Sema &S, const ObjCMessageExpr *Msg) {
2480   applyCocoaAPICheck(S, Msg, diag::warn_objc_redundant_literal_use,
2481                      edit::rewriteObjCRedundantCallWithLiteral);
2482 }
2483 
2484 static void checkFoundationAPI(Sema &S, SourceLocation Loc,
2485                                const ObjCMethodDecl *Method,
2486                                ArrayRef<Expr *> Args, QualType ReceiverType,
2487                                bool IsClassObjectCall) {
2488   // Check if this is a performSelector method that uses a selector that returns
2489   // a record or a vector type.
2490   if (Method->getSelector().getMethodFamily() != OMF_performSelector ||
2491       Args.empty())
2492     return;
2493   const auto *SE = dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens());
2494   if (!SE)
2495     return;
2496   ObjCMethodDecl *ImpliedMethod;
2497   if (!IsClassObjectCall) {
2498     const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>();
2499     if (!OPT || !OPT->getInterfaceDecl())
2500       return;
2501     ImpliedMethod =
2502         OPT->getInterfaceDecl()->lookupInstanceMethod(SE->getSelector());
2503     if (!ImpliedMethod)
2504       ImpliedMethod =
2505           OPT->getInterfaceDecl()->lookupPrivateMethod(SE->getSelector());
2506   } else {
2507     const auto *IT = ReceiverType->getAs<ObjCInterfaceType>();
2508     if (!IT)
2509       return;
2510     ImpliedMethod = IT->getDecl()->lookupClassMethod(SE->getSelector());
2511     if (!ImpliedMethod)
2512       ImpliedMethod =
2513           IT->getDecl()->lookupPrivateClassMethod(SE->getSelector());
2514   }
2515   if (!ImpliedMethod)
2516     return;
2517   QualType Ret = ImpliedMethod->getReturnType();
2518   if (Ret->isRecordType() || Ret->isVectorType() || Ret->isExtVectorType()) {
2519     S.Diag(Loc, diag::warn_objc_unsafe_perform_selector)
2520         << Method->getSelector()
2521         << (!Ret->isRecordType()
2522                 ? /*Vector*/ 2
2523                 : Ret->isUnionType() ? /*Union*/ 1 : /*Struct*/ 0);
2524     S.Diag(ImpliedMethod->getBeginLoc(),
2525            diag::note_objc_unsafe_perform_selector_method_declared_here)
2526         << ImpliedMethod->getSelector() << Ret;
2527   }
2528 }
2529 
2530 /// Diagnose use of %s directive in an NSString which is being passed
2531 /// as formatting string to formatting method.
2532 static void
2533 DiagnoseCStringFormatDirectiveInObjCAPI(Sema &S,
2534                                         ObjCMethodDecl *Method,
2535                                         Selector Sel,
2536                                         Expr **Args, unsigned NumArgs) {
2537   unsigned Idx = 0;
2538   bool Format = false;
2539   ObjCStringFormatFamily SFFamily = Sel.getStringFormatFamily();
2540   if (SFFamily == ObjCStringFormatFamily::SFF_NSString) {
2541     Idx = 0;
2542     Format = true;
2543   }
2544   else if (Method) {
2545     for (const auto *I : Method->specific_attrs<FormatAttr>()) {
2546       if (S.GetFormatNSStringIdx(I, Idx)) {
2547         Format = true;
2548         break;
2549       }
2550     }
2551   }
2552   if (!Format || NumArgs <= Idx)
2553     return;
2554 
2555   Expr *FormatExpr = Args[Idx];
2556   if (ObjCStringLiteral *OSL =
2557       dyn_cast<ObjCStringLiteral>(FormatExpr->IgnoreParenImpCasts())) {
2558     StringLiteral *FormatString = OSL->getString();
2559     if (S.FormatStringHasSArg(FormatString)) {
2560       S.Diag(FormatExpr->getExprLoc(), diag::warn_objc_cdirective_format_string)
2561         << "%s" << 0 << 0;
2562       if (Method)
2563         S.Diag(Method->getLocation(), diag::note_method_declared_at)
2564           << Method->getDeclName();
2565     }
2566   }
2567 }
2568 
2569 /// Build an Objective-C class message expression.
2570 ///
2571 /// This routine takes care of both normal class messages and
2572 /// class messages to the superclass.
2573 ///
2574 /// \param ReceiverTypeInfo Type source information that describes the
2575 /// receiver of this message. This may be NULL, in which case we are
2576 /// sending to the superclass and \p SuperLoc must be a valid source
2577 /// location.
2578 
2579 /// \param ReceiverType The type of the object receiving the
2580 /// message. When \p ReceiverTypeInfo is non-NULL, this is the same
2581 /// type as that refers to. For a superclass send, this is the type of
2582 /// the superclass.
2583 ///
2584 /// \param SuperLoc The location of the "super" keyword in a
2585 /// superclass message.
2586 ///
2587 /// \param Sel The selector to which the message is being sent.
2588 ///
2589 /// \param Method The method that this class message is invoking, if
2590 /// already known.
2591 ///
2592 /// \param LBracLoc The location of the opening square bracket ']'.
2593 ///
2594 /// \param RBracLoc The location of the closing square bracket ']'.
2595 ///
2596 /// \param ArgsIn The message arguments.
2597 ExprResult Sema::BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
2598                                    QualType ReceiverType,
2599                                    SourceLocation SuperLoc,
2600                                    Selector Sel,
2601                                    ObjCMethodDecl *Method,
2602                                    SourceLocation LBracLoc,
2603                                    ArrayRef<SourceLocation> SelectorLocs,
2604                                    SourceLocation RBracLoc,
2605                                    MultiExprArg ArgsIn,
2606                                    bool isImplicit) {
2607   SourceLocation Loc = SuperLoc.isValid()? SuperLoc
2608     : ReceiverTypeInfo->getTypeLoc().getSourceRange().getBegin();
2609   if (LBracLoc.isInvalid()) {
2610     Diag(Loc, diag::err_missing_open_square_message_send)
2611       << FixItHint::CreateInsertion(Loc, "[");
2612     LBracLoc = Loc;
2613   }
2614   ArrayRef<SourceLocation> SelectorSlotLocs;
2615   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
2616     SelectorSlotLocs = SelectorLocs;
2617   else
2618     SelectorSlotLocs = Loc;
2619   SourceLocation SelLoc = SelectorSlotLocs.front();
2620 
2621   if (ReceiverType->isDependentType()) {
2622     // If the receiver type is dependent, we can't type-check anything
2623     // at this point. Build a dependent expression.
2624     unsigned NumArgs = ArgsIn.size();
2625     Expr **Args = ArgsIn.data();
2626     assert(SuperLoc.isInvalid() && "Message to super with dependent type");
2627     return ObjCMessageExpr::Create(
2628         Context, ReceiverType, VK_RValue, LBracLoc, ReceiverTypeInfo, Sel,
2629         SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs), RBracLoc,
2630         isImplicit);
2631   }
2632 
2633   // Find the class to which we are sending this message.
2634   ObjCInterfaceDecl *Class = nullptr;
2635   const ObjCObjectType *ClassType = ReceiverType->getAs<ObjCObjectType>();
2636   if (!ClassType || !(Class = ClassType->getInterface())) {
2637     Diag(Loc, diag::err_invalid_receiver_class_message)
2638       << ReceiverType;
2639     return ExprError();
2640   }
2641   assert(Class && "We don't know which class we're messaging?");
2642   // objc++ diagnoses during typename annotation.
2643   if (!getLangOpts().CPlusPlus)
2644     (void)DiagnoseUseOfDecl(Class, SelectorSlotLocs);
2645   // Find the method we are messaging.
2646   if (!Method) {
2647     SourceRange TypeRange
2648       = SuperLoc.isValid()? SourceRange(SuperLoc)
2649                           : ReceiverTypeInfo->getTypeLoc().getSourceRange();
2650     if (RequireCompleteType(Loc, Context.getObjCInterfaceType(Class),
2651                             (getLangOpts().ObjCAutoRefCount
2652                                ? diag::err_arc_receiver_forward_class
2653                                : diag::warn_receiver_forward_class),
2654                             TypeRange)) {
2655       // A forward class used in messaging is treated as a 'Class'
2656       Method = LookupFactoryMethodInGlobalPool(Sel,
2657                                                SourceRange(LBracLoc, RBracLoc));
2658       if (Method && !getLangOpts().ObjCAutoRefCount)
2659         Diag(Method->getLocation(), diag::note_method_sent_forward_class)
2660           << Method->getDeclName();
2661     }
2662     if (!Method)
2663       Method = Class->lookupClassMethod(Sel);
2664 
2665     // If we have an implementation in scope, check "private" methods.
2666     if (!Method)
2667       Method = Class->lookupPrivateClassMethod(Sel);
2668 
2669     if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs,
2670                                     nullptr, false, false, Class))
2671       return ExprError();
2672   }
2673 
2674   // Check the argument types and determine the result type.
2675   QualType ReturnType;
2676   ExprValueKind VK = VK_RValue;
2677 
2678   unsigned NumArgs = ArgsIn.size();
2679   Expr **Args = ArgsIn.data();
2680   if (CheckMessageArgumentTypes(/*Receiver=*/nullptr, ReceiverType,
2681                                 MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
2682                                 Method, true, SuperLoc.isValid(), LBracLoc,
2683                                 RBracLoc, SourceRange(), ReturnType, VK))
2684     return ExprError();
2685 
2686   if (Method && !Method->getReturnType()->isVoidType() &&
2687       RequireCompleteType(LBracLoc, Method->getReturnType(),
2688                           diag::err_illegal_message_expr_incomplete_type))
2689     return ExprError();
2690 
2691   if (Method && Method->isDirectMethod() && SuperLoc.isValid()) {
2692     Diag(SuperLoc, diag::err_messaging_super_with_direct_method)
2693         << FixItHint::CreateReplacement(
2694                SuperLoc, getLangOpts().ObjCAutoRefCount
2695                              ? "self"
2696                              : Method->getClassInterface()->getName());
2697     Diag(Method->getLocation(), diag::note_direct_method_declared_at)
2698         << Method->getDeclName();
2699   }
2700 
2701   // Warn about explicit call of +initialize on its own class. But not on 'super'.
2702   if (Method && Method->getMethodFamily() == OMF_initialize) {
2703     if (!SuperLoc.isValid()) {
2704       const ObjCInterfaceDecl *ID =
2705         dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext());
2706       if (ID == Class) {
2707         Diag(Loc, diag::warn_direct_initialize_call);
2708         Diag(Method->getLocation(), diag::note_method_declared_at)
2709           << Method->getDeclName();
2710       }
2711     }
2712     else if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
2713       // [super initialize] is allowed only within an +initialize implementation
2714       if (CurMeth->getMethodFamily() != OMF_initialize) {
2715         Diag(Loc, diag::warn_direct_super_initialize_call);
2716         Diag(Method->getLocation(), diag::note_method_declared_at)
2717           << Method->getDeclName();
2718         Diag(CurMeth->getLocation(), diag::note_method_declared_at)
2719         << CurMeth->getDeclName();
2720       }
2721     }
2722   }
2723 
2724   DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
2725 
2726   // Construct the appropriate ObjCMessageExpr.
2727   ObjCMessageExpr *Result;
2728   if (SuperLoc.isValid())
2729     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
2730                                      SuperLoc, /*IsInstanceSuper=*/false,
2731                                      ReceiverType, Sel, SelectorLocs,
2732                                      Method, makeArrayRef(Args, NumArgs),
2733                                      RBracLoc, isImplicit);
2734   else {
2735     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
2736                                      ReceiverTypeInfo, Sel, SelectorLocs,
2737                                      Method, makeArrayRef(Args, NumArgs),
2738                                      RBracLoc, isImplicit);
2739     if (!isImplicit)
2740       checkCocoaAPI(*this, Result);
2741   }
2742   if (Method)
2743     checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
2744                        ReceiverType, /*IsClassObjectCall=*/true);
2745   return MaybeBindToTemporary(Result);
2746 }
2747 
2748 // ActOnClassMessage - used for both unary and keyword messages.
2749 // ArgExprs is optional - if it is present, the number of expressions
2750 // is obtained from Sel.getNumArgs().
2751 ExprResult Sema::ActOnClassMessage(Scope *S,
2752                                    ParsedType Receiver,
2753                                    Selector Sel,
2754                                    SourceLocation LBracLoc,
2755                                    ArrayRef<SourceLocation> SelectorLocs,
2756                                    SourceLocation RBracLoc,
2757                                    MultiExprArg Args) {
2758   TypeSourceInfo *ReceiverTypeInfo;
2759   QualType ReceiverType = GetTypeFromParser(Receiver, &ReceiverTypeInfo);
2760   if (ReceiverType.isNull())
2761     return ExprError();
2762 
2763   if (!ReceiverTypeInfo)
2764     ReceiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType, LBracLoc);
2765 
2766   return BuildClassMessage(ReceiverTypeInfo, ReceiverType,
2767                            /*SuperLoc=*/SourceLocation(), Sel,
2768                            /*Method=*/nullptr, LBracLoc, SelectorLocs, RBracLoc,
2769                            Args);
2770 }
2771 
2772 ExprResult Sema::BuildInstanceMessageImplicit(Expr *Receiver,
2773                                               QualType ReceiverType,
2774                                               SourceLocation Loc,
2775                                               Selector Sel,
2776                                               ObjCMethodDecl *Method,
2777                                               MultiExprArg Args) {
2778   return BuildInstanceMessage(Receiver, ReceiverType,
2779                               /*SuperLoc=*/!Receiver ? Loc : SourceLocation(),
2780                               Sel, Method, Loc, Loc, Loc, Args,
2781                               /*isImplicit=*/true);
2782 }
2783 
2784 static bool isMethodDeclaredInRootProtocol(Sema &S, const ObjCMethodDecl *M) {
2785   if (!S.NSAPIObj)
2786     return false;
2787   const auto *Protocol = dyn_cast<ObjCProtocolDecl>(M->getDeclContext());
2788   if (!Protocol)
2789     return false;
2790   const IdentifierInfo *II = S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
2791   if (const auto *RootClass = dyn_cast_or_null<ObjCInterfaceDecl>(
2792           S.LookupSingleName(S.TUScope, II, Protocol->getBeginLoc(),
2793                              Sema::LookupOrdinaryName))) {
2794     for (const ObjCProtocolDecl *P : RootClass->all_referenced_protocols()) {
2795       if (P->getCanonicalDecl() == Protocol->getCanonicalDecl())
2796         return true;
2797     }
2798   }
2799   return false;
2800 }
2801 
2802 /// Build an Objective-C instance message expression.
2803 ///
2804 /// This routine takes care of both normal instance messages and
2805 /// instance messages to the superclass instance.
2806 ///
2807 /// \param Receiver The expression that computes the object that will
2808 /// receive this message. This may be empty, in which case we are
2809 /// sending to the superclass instance and \p SuperLoc must be a valid
2810 /// source location.
2811 ///
2812 /// \param ReceiverType The (static) type of the object receiving the
2813 /// message. When a \p Receiver expression is provided, this is the
2814 /// same type as that expression. For a superclass instance send, this
2815 /// is a pointer to the type of the superclass.
2816 ///
2817 /// \param SuperLoc The location of the "super" keyword in a
2818 /// superclass instance message.
2819 ///
2820 /// \param Sel The selector to which the message is being sent.
2821 ///
2822 /// \param Method The method that this instance message is invoking, if
2823 /// already known.
2824 ///
2825 /// \param LBracLoc The location of the opening square bracket ']'.
2826 ///
2827 /// \param RBracLoc The location of the closing square bracket ']'.
2828 ///
2829 /// \param ArgsIn The message arguments.
2830 ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
2831                                       QualType ReceiverType,
2832                                       SourceLocation SuperLoc,
2833                                       Selector Sel,
2834                                       ObjCMethodDecl *Method,
2835                                       SourceLocation LBracLoc,
2836                                       ArrayRef<SourceLocation> SelectorLocs,
2837                                       SourceLocation RBracLoc,
2838                                       MultiExprArg ArgsIn,
2839                                       bool isImplicit) {
2840   assert((Receiver || SuperLoc.isValid()) && "If the Receiver is null, the "
2841                                              "SuperLoc must be valid so we can "
2842                                              "use it instead.");
2843 
2844   // The location of the receiver.
2845   SourceLocation Loc = SuperLoc.isValid() ? SuperLoc : Receiver->getBeginLoc();
2846   SourceRange RecRange =
2847       SuperLoc.isValid()? SuperLoc : Receiver->getSourceRange();
2848   ArrayRef<SourceLocation> SelectorSlotLocs;
2849   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
2850     SelectorSlotLocs = SelectorLocs;
2851   else
2852     SelectorSlotLocs = Loc;
2853   SourceLocation SelLoc = SelectorSlotLocs.front();
2854 
2855   if (LBracLoc.isInvalid()) {
2856     Diag(Loc, diag::err_missing_open_square_message_send)
2857       << FixItHint::CreateInsertion(Loc, "[");
2858     LBracLoc = Loc;
2859   }
2860 
2861   // If we have a receiver expression, perform appropriate promotions
2862   // and determine receiver type.
2863   if (Receiver) {
2864     if (Receiver->hasPlaceholderType()) {
2865       ExprResult Result;
2866       if (Receiver->getType() == Context.UnknownAnyTy)
2867         Result = forceUnknownAnyToType(Receiver, Context.getObjCIdType());
2868       else
2869         Result = CheckPlaceholderExpr(Receiver);
2870       if (Result.isInvalid()) return ExprError();
2871       Receiver = Result.get();
2872     }
2873 
2874     if (Receiver->isTypeDependent()) {
2875       // If the receiver is type-dependent, we can't type-check anything
2876       // at this point. Build a dependent expression.
2877       unsigned NumArgs = ArgsIn.size();
2878       Expr **Args = ArgsIn.data();
2879       assert(SuperLoc.isInvalid() && "Message to super with dependent type");
2880       return ObjCMessageExpr::Create(
2881           Context, Context.DependentTy, VK_RValue, LBracLoc, Receiver, Sel,
2882           SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs),
2883           RBracLoc, isImplicit);
2884     }
2885 
2886     // If necessary, apply function/array conversion to the receiver.
2887     // C99 6.7.5.3p[7,8].
2888     ExprResult Result = DefaultFunctionArrayLvalueConversion(Receiver);
2889     if (Result.isInvalid())
2890       return ExprError();
2891     Receiver = Result.get();
2892     ReceiverType = Receiver->getType();
2893 
2894     // If the receiver is an ObjC pointer, a block pointer, or an
2895     // __attribute__((NSObject)) pointer, we don't need to do any
2896     // special conversion in order to look up a receiver.
2897     if (ReceiverType->isObjCRetainableType()) {
2898       // do nothing
2899     } else if (!getLangOpts().ObjCAutoRefCount &&
2900                !Context.getObjCIdType().isNull() &&
2901                (ReceiverType->isPointerType() ||
2902                 ReceiverType->isIntegerType())) {
2903       // Implicitly convert integers and pointers to 'id' but emit a warning.
2904       // But not in ARC.
2905       Diag(Loc, diag::warn_bad_receiver_type) << ReceiverType << RecRange;
2906       if (ReceiverType->isPointerType()) {
2907         Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
2908                                      CK_CPointerToObjCPointerCast).get();
2909       } else {
2910         // TODO: specialized warning on null receivers?
2911         bool IsNull = Receiver->isNullPointerConstant(Context,
2912                                               Expr::NPC_ValueDependentIsNull);
2913         CastKind Kind = IsNull ? CK_NullToPointer : CK_IntegralToPointer;
2914         Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
2915                                      Kind).get();
2916       }
2917       ReceiverType = Receiver->getType();
2918     } else if (getLangOpts().CPlusPlus) {
2919       // The receiver must be a complete type.
2920       if (RequireCompleteType(Loc, Receiver->getType(),
2921                               diag::err_incomplete_receiver_type))
2922         return ExprError();
2923 
2924       ExprResult result = PerformContextuallyConvertToObjCPointer(Receiver);
2925       if (result.isUsable()) {
2926         Receiver = result.get();
2927         ReceiverType = Receiver->getType();
2928       }
2929     }
2930   }
2931 
2932   // There's a somewhat weird interaction here where we assume that we
2933   // won't actually have a method unless we also don't need to do some
2934   // of the more detailed type-checking on the receiver.
2935 
2936   if (!Method) {
2937     // Handle messages to id and __kindof types (where we use the
2938     // global method pool).
2939     const ObjCObjectType *typeBound = nullptr;
2940     bool receiverIsIdLike = ReceiverType->isObjCIdOrObjectKindOfType(Context,
2941                                                                      typeBound);
2942     if (receiverIsIdLike || ReceiverType->isBlockPointerType() ||
2943         (Receiver && Context.isObjCNSObjectType(Receiver->getType()))) {
2944       SmallVector<ObjCMethodDecl*, 4> Methods;
2945       // If we have a type bound, further filter the methods.
2946       CollectMultipleMethodsInGlobalPool(Sel, Methods, true/*InstanceFirst*/,
2947                                          true/*CheckTheOther*/, typeBound);
2948       if (!Methods.empty()) {
2949         // We choose the first method as the initial candidate, then try to
2950         // select a better one.
2951         Method = Methods[0];
2952 
2953         if (ObjCMethodDecl *BestMethod =
2954             SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(), Methods))
2955           Method = BestMethod;
2956 
2957         if (!AreMultipleMethodsInGlobalPool(Sel, Method,
2958                                             SourceRange(LBracLoc, RBracLoc),
2959                                             receiverIsIdLike, Methods))
2960           DiagnoseUseOfDecl(Method, SelectorSlotLocs);
2961       }
2962     } else if (ReceiverType->isObjCClassOrClassKindOfType() ||
2963                ReceiverType->isObjCQualifiedClassType()) {
2964       // Handle messages to Class.
2965       // We allow sending a message to a qualified Class ("Class<foo>"), which
2966       // is ok as long as one of the protocols implements the selector (if not,
2967       // warn).
2968       if (!ReceiverType->isObjCClassOrClassKindOfType()) {
2969         const ObjCObjectPointerType *QClassTy
2970           = ReceiverType->getAsObjCQualifiedClassType();
2971         // Search protocols for class methods.
2972         Method = LookupMethodInQualifiedType(Sel, QClassTy, false);
2973         if (!Method) {
2974           Method = LookupMethodInQualifiedType(Sel, QClassTy, true);
2975           // warn if instance method found for a Class message.
2976           if (Method && !isMethodDeclaredInRootProtocol(*this, Method)) {
2977             Diag(SelLoc, diag::warn_instance_method_on_class_found)
2978               << Method->getSelector() << Sel;
2979             Diag(Method->getLocation(), diag::note_method_declared_at)
2980               << Method->getDeclName();
2981           }
2982         }
2983       } else {
2984         if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
2985           if (ObjCInterfaceDecl *ClassDecl = CurMeth->getClassInterface()) {
2986             // As a guess, try looking for the method in the current interface.
2987             // This very well may not produce the "right" method.
2988 
2989             // First check the public methods in the class interface.
2990             Method = ClassDecl->lookupClassMethod(Sel);
2991 
2992             if (!Method)
2993               Method = ClassDecl->lookupPrivateClassMethod(Sel);
2994 
2995             if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
2996               return ExprError();
2997           }
2998         }
2999         if (!Method) {
3000           // If not messaging 'self', look for any factory method named 'Sel'.
3001           if (!Receiver || !isSelfExpr(Receiver)) {
3002             // If no class (factory) method was found, check if an _instance_
3003             // method of the same name exists in the root class only.
3004             SmallVector<ObjCMethodDecl*, 4> Methods;
3005             CollectMultipleMethodsInGlobalPool(Sel, Methods,
3006                                                false/*InstanceFirst*/,
3007                                                true/*CheckTheOther*/);
3008             if (!Methods.empty()) {
3009               // We choose the first method as the initial candidate, then try
3010               // to select a better one.
3011               Method = Methods[0];
3012 
3013               // If we find an instance method, emit warning.
3014               if (Method->isInstanceMethod()) {
3015                 if (const ObjCInterfaceDecl *ID =
3016                     dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext())) {
3017                   if (ID->getSuperClass())
3018                     Diag(SelLoc, diag::warn_root_inst_method_not_found)
3019                         << Sel << SourceRange(LBracLoc, RBracLoc);
3020                 }
3021               }
3022 
3023              if (ObjCMethodDecl *BestMethod =
3024                  SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
3025                                   Methods))
3026                Method = BestMethod;
3027             }
3028           }
3029         }
3030       }
3031     } else {
3032       ObjCInterfaceDecl *ClassDecl = nullptr;
3033 
3034       // We allow sending a message to a qualified ID ("id<foo>"), which is ok as
3035       // long as one of the protocols implements the selector (if not, warn).
3036       // And as long as message is not deprecated/unavailable (warn if it is).
3037       if (const ObjCObjectPointerType *QIdTy
3038                                    = ReceiverType->getAsObjCQualifiedIdType()) {
3039         // Search protocols for instance methods.
3040         Method = LookupMethodInQualifiedType(Sel, QIdTy, true);
3041         if (!Method)
3042           Method = LookupMethodInQualifiedType(Sel, QIdTy, false);
3043         if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
3044           return ExprError();
3045       } else if (const ObjCObjectPointerType *OCIType
3046                    = ReceiverType->getAsObjCInterfacePointerType()) {
3047         // We allow sending a message to a pointer to an interface (an object).
3048         ClassDecl = OCIType->getInterfaceDecl();
3049 
3050         // Try to complete the type. Under ARC, this is a hard error from which
3051         // we don't try to recover.
3052         // FIXME: In the non-ARC case, this will still be a hard error if the
3053         // definition is found in a module that's not visible.
3054         const ObjCInterfaceDecl *forwardClass = nullptr;
3055         if (RequireCompleteType(Loc, OCIType->getPointeeType(),
3056                                 getLangOpts().ObjCAutoRefCount
3057                                     ? diag::err_arc_receiver_forward_instance
3058                                     : diag::warn_receiver_forward_instance,
3059                                 RecRange)) {
3060           if (getLangOpts().ObjCAutoRefCount)
3061             return ExprError();
3062 
3063           forwardClass = OCIType->getInterfaceDecl();
3064           Diag(Receiver ? Receiver->getBeginLoc() : SuperLoc,
3065                diag::note_receiver_is_id);
3066           Method = nullptr;
3067         } else {
3068           Method = ClassDecl->lookupInstanceMethod(Sel);
3069         }
3070 
3071         if (!Method)
3072           // Search protocol qualifiers.
3073           Method = LookupMethodInQualifiedType(Sel, OCIType, true);
3074 
3075         if (!Method) {
3076           // If we have implementations in scope, check "private" methods.
3077           Method = ClassDecl->lookupPrivateMethod(Sel);
3078 
3079           if (!Method && getLangOpts().ObjCAutoRefCount) {
3080             Diag(SelLoc, diag::err_arc_may_not_respond)
3081               << OCIType->getPointeeType() << Sel << RecRange
3082               << SourceRange(SelectorLocs.front(), SelectorLocs.back());
3083             return ExprError();
3084           }
3085 
3086           if (!Method && (!Receiver || !isSelfExpr(Receiver))) {
3087             // If we still haven't found a method, look in the global pool. This
3088             // behavior isn't very desirable, however we need it for GCC
3089             // compatibility. FIXME: should we deviate??
3090             if (OCIType->qual_empty()) {
3091               SmallVector<ObjCMethodDecl*, 4> Methods;
3092               CollectMultipleMethodsInGlobalPool(Sel, Methods,
3093                                                  true/*InstanceFirst*/,
3094                                                  false/*CheckTheOther*/);
3095               if (!Methods.empty()) {
3096                 // We choose the first method as the initial candidate, then try
3097                 // to select a better one.
3098                 Method = Methods[0];
3099 
3100                 if (ObjCMethodDecl *BestMethod =
3101                     SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
3102                                      Methods))
3103                   Method = BestMethod;
3104 
3105                 AreMultipleMethodsInGlobalPool(Sel, Method,
3106                                                SourceRange(LBracLoc, RBracLoc),
3107                                                true/*receiverIdOrClass*/,
3108                                                Methods);
3109               }
3110               if (Method && !forwardClass)
3111                 Diag(SelLoc, diag::warn_maynot_respond)
3112                   << OCIType->getInterfaceDecl()->getIdentifier()
3113                   << Sel << RecRange;
3114             }
3115           }
3116         }
3117         if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs, forwardClass))
3118           return ExprError();
3119       } else {
3120         // Reject other random receiver types (e.g. structs).
3121         Diag(Loc, diag::err_bad_receiver_type) << ReceiverType << RecRange;
3122         return ExprError();
3123       }
3124     }
3125   }
3126 
3127   FunctionScopeInfo *DIFunctionScopeInfo =
3128     (Method && Method->getMethodFamily() == OMF_init)
3129       ? getEnclosingFunction() : nullptr;
3130 
3131   if (Method && Method->isDirectMethod()) {
3132     if (ReceiverType->isObjCIdType() && !isImplicit) {
3133       Diag(Receiver->getExprLoc(),
3134            diag::err_messaging_unqualified_id_with_direct_method);
3135       Diag(Method->getLocation(), diag::note_direct_method_declared_at)
3136           << Method->getDeclName();
3137     }
3138 
3139     // Under ARC, self can't be assigned, and doing a direct call to `self`
3140     // when it's a Class is hence safe.  For other cases, we can't trust `self`
3141     // is what we think it is, so we reject it.
3142     if (ReceiverType->isObjCClassType() && !isImplicit &&
3143         !(Receiver->isObjCSelfExpr() && getLangOpts().ObjCAutoRefCount)) {
3144       {
3145         auto Builder = Diag(Receiver->getExprLoc(),
3146                             diag::err_messaging_class_with_direct_method);
3147         if (Receiver->isObjCSelfExpr()) {
3148           Builder.AddFixItHint(FixItHint::CreateReplacement(
3149               RecRange, Method->getClassInterface()->getName()));
3150         }
3151       }
3152       Diag(Method->getLocation(), diag::note_direct_method_declared_at)
3153           << Method->getDeclName();
3154     }
3155 
3156     if (SuperLoc.isValid()) {
3157       {
3158         auto Builder =
3159             Diag(SuperLoc, diag::err_messaging_super_with_direct_method);
3160         if (ReceiverType->isObjCClassType()) {
3161           Builder.AddFixItHint(FixItHint::CreateReplacement(
3162               SuperLoc, Method->getClassInterface()->getName()));
3163         } else {
3164           Builder.AddFixItHint(FixItHint::CreateReplacement(SuperLoc, "self"));
3165         }
3166       }
3167       Diag(Method->getLocation(), diag::note_direct_method_declared_at)
3168           << Method->getDeclName();
3169     }
3170   } else if (ReceiverType->isObjCIdType() && !isImplicit) {
3171     Diag(Receiver->getExprLoc(), diag::warn_messaging_unqualified_id);
3172   }
3173 
3174   if (DIFunctionScopeInfo &&
3175       DIFunctionScopeInfo->ObjCIsDesignatedInit &&
3176       (SuperLoc.isValid() || isSelfExpr(Receiver))) {
3177     bool isDesignatedInitChain = false;
3178     if (SuperLoc.isValid()) {
3179       if (const ObjCObjectPointerType *
3180             OCIType = ReceiverType->getAsObjCInterfacePointerType()) {
3181         if (const ObjCInterfaceDecl *ID = OCIType->getInterfaceDecl()) {
3182           // Either we know this is a designated initializer or we
3183           // conservatively assume it because we don't know for sure.
3184           if (!ID->declaresOrInheritsDesignatedInitializers() ||
3185               ID->isDesignatedInitializer(Sel)) {
3186             isDesignatedInitChain = true;
3187             DIFunctionScopeInfo->ObjCWarnForNoDesignatedInitChain = false;
3188           }
3189         }
3190       }
3191     }
3192     if (!isDesignatedInitChain) {
3193       const ObjCMethodDecl *InitMethod = nullptr;
3194       bool isDesignated =
3195         getCurMethodDecl()->isDesignatedInitializerForTheInterface(&InitMethod);
3196       assert(isDesignated && InitMethod);
3197       (void)isDesignated;
3198       Diag(SelLoc, SuperLoc.isValid() ?
3199              diag::warn_objc_designated_init_non_designated_init_call :
3200              diag::warn_objc_designated_init_non_super_designated_init_call);
3201       Diag(InitMethod->getLocation(),
3202            diag::note_objc_designated_init_marked_here);
3203     }
3204   }
3205 
3206   if (DIFunctionScopeInfo &&
3207       DIFunctionScopeInfo->ObjCIsSecondaryInit &&
3208       (SuperLoc.isValid() || isSelfExpr(Receiver))) {
3209     if (SuperLoc.isValid()) {
3210       Diag(SelLoc, diag::warn_objc_secondary_init_super_init_call);
3211     } else {
3212       DIFunctionScopeInfo->ObjCWarnForNoInitDelegation = false;
3213     }
3214   }
3215 
3216   // Check the message arguments.
3217   unsigned NumArgs = ArgsIn.size();
3218   Expr **Args = ArgsIn.data();
3219   QualType ReturnType;
3220   ExprValueKind VK = VK_RValue;
3221   bool ClassMessage = (ReceiverType->isObjCClassType() ||
3222                        ReceiverType->isObjCQualifiedClassType());
3223   if (CheckMessageArgumentTypes(Receiver, ReceiverType,
3224                                 MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
3225                                 Method, ClassMessage, SuperLoc.isValid(),
3226                                 LBracLoc, RBracLoc, RecRange, ReturnType, VK))
3227     return ExprError();
3228 
3229   if (Method && !Method->getReturnType()->isVoidType() &&
3230       RequireCompleteType(LBracLoc, Method->getReturnType(),
3231                           diag::err_illegal_message_expr_incomplete_type))
3232     return ExprError();
3233 
3234   // In ARC, forbid the user from sending messages to
3235   // retain/release/autorelease/dealloc/retainCount explicitly.
3236   if (getLangOpts().ObjCAutoRefCount) {
3237     ObjCMethodFamily family =
3238       (Method ? Method->getMethodFamily() : Sel.getMethodFamily());
3239     switch (family) {
3240     case OMF_init:
3241       if (Method)
3242         checkInitMethod(Method, ReceiverType);
3243       break;
3244 
3245     case OMF_None:
3246     case OMF_alloc:
3247     case OMF_copy:
3248     case OMF_finalize:
3249     case OMF_mutableCopy:
3250     case OMF_new:
3251     case OMF_self:
3252     case OMF_initialize:
3253       break;
3254 
3255     case OMF_dealloc:
3256     case OMF_retain:
3257     case OMF_release:
3258     case OMF_autorelease:
3259     case OMF_retainCount:
3260       Diag(SelLoc, diag::err_arc_illegal_explicit_message)
3261         << Sel << RecRange;
3262       break;
3263 
3264     case OMF_performSelector:
3265       if (Method && NumArgs >= 1) {
3266         if (const auto *SelExp =
3267                 dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens())) {
3268           Selector ArgSel = SelExp->getSelector();
3269           ObjCMethodDecl *SelMethod =
3270             LookupInstanceMethodInGlobalPool(ArgSel,
3271                                              SelExp->getSourceRange());
3272           if (!SelMethod)
3273             SelMethod =
3274               LookupFactoryMethodInGlobalPool(ArgSel,
3275                                               SelExp->getSourceRange());
3276           if (SelMethod) {
3277             ObjCMethodFamily SelFamily = SelMethod->getMethodFamily();
3278             switch (SelFamily) {
3279               case OMF_alloc:
3280               case OMF_copy:
3281               case OMF_mutableCopy:
3282               case OMF_new:
3283               case OMF_init:
3284                 // Issue error, unless ns_returns_not_retained.
3285                 if (!SelMethod->hasAttr<NSReturnsNotRetainedAttr>()) {
3286                   // selector names a +1 method
3287                   Diag(SelLoc,
3288                        diag::err_arc_perform_selector_retains);
3289                   Diag(SelMethod->getLocation(), diag::note_method_declared_at)
3290                     << SelMethod->getDeclName();
3291                 }
3292                 break;
3293               default:
3294                 // +0 call. OK. unless ns_returns_retained.
3295                 if (SelMethod->hasAttr<NSReturnsRetainedAttr>()) {
3296                   // selector names a +1 method
3297                   Diag(SelLoc,
3298                        diag::err_arc_perform_selector_retains);
3299                   Diag(SelMethod->getLocation(), diag::note_method_declared_at)
3300                     << SelMethod->getDeclName();
3301                 }
3302                 break;
3303             }
3304           }
3305         } else {
3306           // error (may leak).
3307           Diag(SelLoc, diag::warn_arc_perform_selector_leaks);
3308           Diag(Args[0]->getExprLoc(), diag::note_used_here);
3309         }
3310       }
3311       break;
3312     }
3313   }
3314 
3315   DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
3316 
3317   // Construct the appropriate ObjCMessageExpr instance.
3318   ObjCMessageExpr *Result;
3319   if (SuperLoc.isValid())
3320     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
3321                                      SuperLoc,  /*IsInstanceSuper=*/true,
3322                                      ReceiverType, Sel, SelectorLocs, Method,
3323                                      makeArrayRef(Args, NumArgs), RBracLoc,
3324                                      isImplicit);
3325   else {
3326     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
3327                                      Receiver, Sel, SelectorLocs, Method,
3328                                      makeArrayRef(Args, NumArgs), RBracLoc,
3329                                      isImplicit);
3330     if (!isImplicit)
3331       checkCocoaAPI(*this, Result);
3332   }
3333   if (Method) {
3334     bool IsClassObjectCall = ClassMessage;
3335     // 'self' message receivers in class methods should be treated as message
3336     // sends to the class object in order for the semantic checks to be
3337     // performed correctly. Messages to 'super' already count as class messages,
3338     // so they don't need to be handled here.
3339     if (Receiver && isSelfExpr(Receiver)) {
3340       if (const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
3341         if (OPT->getObjectType()->isObjCClass()) {
3342           if (const auto *CurMeth = getCurMethodDecl()) {
3343             IsClassObjectCall = true;
3344             ReceiverType =
3345                 Context.getObjCInterfaceType(CurMeth->getClassInterface());
3346           }
3347         }
3348       }
3349     }
3350     checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
3351                        ReceiverType, IsClassObjectCall);
3352   }
3353 
3354   if (getLangOpts().ObjCAutoRefCount) {
3355     // In ARC, annotate delegate init calls.
3356     if (Result->getMethodFamily() == OMF_init &&
3357         (SuperLoc.isValid() || isSelfExpr(Receiver))) {
3358       // Only consider init calls *directly* in init implementations,
3359       // not within blocks.
3360       ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(CurContext);
3361       if (method && method->getMethodFamily() == OMF_init) {
3362         // The implicit assignment to self means we also don't want to
3363         // consume the result.
3364         Result->setDelegateInitCall(true);
3365         return Result;
3366       }
3367     }
3368 
3369     // In ARC, check for message sends which are likely to introduce
3370     // retain cycles.
3371     checkRetainCycles(Result);
3372   }
3373 
3374   if (getLangOpts().ObjCWeak) {
3375     if (!isImplicit && Method) {
3376       if (const ObjCPropertyDecl *Prop = Method->findPropertyDecl()) {
3377         bool IsWeak =
3378             Prop->getPropertyAttributes() & ObjCPropertyAttribute::kind_weak;
3379         if (!IsWeak && Sel.isUnarySelector())
3380           IsWeak = ReturnType.getObjCLifetime() & Qualifiers::OCL_Weak;
3381         if (IsWeak && !isUnevaluatedContext() &&
3382             !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, LBracLoc))
3383           getCurFunction()->recordUseOfWeak(Result, Prop);
3384       }
3385     }
3386   }
3387 
3388   CheckObjCCircularContainer(Result);
3389 
3390   return MaybeBindToTemporary(Result);
3391 }
3392 
3393 static void RemoveSelectorFromWarningCache(Sema &S, Expr* Arg) {
3394   if (ObjCSelectorExpr *OSE =
3395       dyn_cast<ObjCSelectorExpr>(Arg->IgnoreParenCasts())) {
3396     Selector Sel = OSE->getSelector();
3397     SourceLocation Loc = OSE->getAtLoc();
3398     auto Pos = S.ReferencedSelectors.find(Sel);
3399     if (Pos != S.ReferencedSelectors.end() && Pos->second == Loc)
3400       S.ReferencedSelectors.erase(Pos);
3401   }
3402 }
3403 
3404 // ActOnInstanceMessage - used for both unary and keyword messages.
3405 // ArgExprs is optional - if it is present, the number of expressions
3406 // is obtained from Sel.getNumArgs().
3407 ExprResult Sema::ActOnInstanceMessage(Scope *S,
3408                                       Expr *Receiver,
3409                                       Selector Sel,
3410                                       SourceLocation LBracLoc,
3411                                       ArrayRef<SourceLocation> SelectorLocs,
3412                                       SourceLocation RBracLoc,
3413                                       MultiExprArg Args) {
3414   if (!Receiver)
3415     return ExprError();
3416 
3417   // A ParenListExpr can show up while doing error recovery with invalid code.
3418   if (isa<ParenListExpr>(Receiver)) {
3419     ExprResult Result = MaybeConvertParenListExprToParenExpr(S, Receiver);
3420     if (Result.isInvalid()) return ExprError();
3421     Receiver = Result.get();
3422   }
3423 
3424   if (RespondsToSelectorSel.isNull()) {
3425     IdentifierInfo *SelectorId = &Context.Idents.get("respondsToSelector");
3426     RespondsToSelectorSel = Context.Selectors.getUnarySelector(SelectorId);
3427   }
3428   if (Sel == RespondsToSelectorSel)
3429     RemoveSelectorFromWarningCache(*this, Args[0]);
3430 
3431   return BuildInstanceMessage(Receiver, Receiver->getType(),
3432                               /*SuperLoc=*/SourceLocation(), Sel,
3433                               /*Method=*/nullptr, LBracLoc, SelectorLocs,
3434                               RBracLoc, Args);
3435 }
3436 
3437 enum ARCConversionTypeClass {
3438   /// int, void, struct A
3439   ACTC_none,
3440 
3441   /// id, void (^)()
3442   ACTC_retainable,
3443 
3444   /// id*, id***, void (^*)(),
3445   ACTC_indirectRetainable,
3446 
3447   /// void* might be a normal C type, or it might a CF type.
3448   ACTC_voidPtr,
3449 
3450   /// struct A*
3451   ACTC_coreFoundation
3452 };
3453 
3454 static bool isAnyRetainable(ARCConversionTypeClass ACTC) {
3455   return (ACTC == ACTC_retainable ||
3456           ACTC == ACTC_coreFoundation ||
3457           ACTC == ACTC_voidPtr);
3458 }
3459 
3460 static bool isAnyCLike(ARCConversionTypeClass ACTC) {
3461   return ACTC == ACTC_none ||
3462          ACTC == ACTC_voidPtr ||
3463          ACTC == ACTC_coreFoundation;
3464 }
3465 
3466 static ARCConversionTypeClass classifyTypeForARCConversion(QualType type) {
3467   bool isIndirect = false;
3468 
3469   // Ignore an outermost reference type.
3470   if (const ReferenceType *ref = type->getAs<ReferenceType>()) {
3471     type = ref->getPointeeType();
3472     isIndirect = true;
3473   }
3474 
3475   // Drill through pointers and arrays recursively.
3476   while (true) {
3477     if (const PointerType *ptr = type->getAs<PointerType>()) {
3478       type = ptr->getPointeeType();
3479 
3480       // The first level of pointer may be the innermost pointer on a CF type.
3481       if (!isIndirect) {
3482         if (type->isVoidType()) return ACTC_voidPtr;
3483         if (type->isRecordType()) return ACTC_coreFoundation;
3484       }
3485     } else if (const ArrayType *array = type->getAsArrayTypeUnsafe()) {
3486       type = QualType(array->getElementType()->getBaseElementTypeUnsafe(), 0);
3487     } else {
3488       break;
3489     }
3490     isIndirect = true;
3491   }
3492 
3493   if (isIndirect) {
3494     if (type->isObjCARCBridgableType())
3495       return ACTC_indirectRetainable;
3496     return ACTC_none;
3497   }
3498 
3499   if (type->isObjCARCBridgableType())
3500     return ACTC_retainable;
3501 
3502   return ACTC_none;
3503 }
3504 
3505 namespace {
3506   /// A result from the cast checker.
3507   enum ACCResult {
3508     /// Cannot be casted.
3509     ACC_invalid,
3510 
3511     /// Can be safely retained or not retained.
3512     ACC_bottom,
3513 
3514     /// Can be casted at +0.
3515     ACC_plusZero,
3516 
3517     /// Can be casted at +1.
3518     ACC_plusOne
3519   };
3520   ACCResult merge(ACCResult left, ACCResult right) {
3521     if (left == right) return left;
3522     if (left == ACC_bottom) return right;
3523     if (right == ACC_bottom) return left;
3524     return ACC_invalid;
3525   }
3526 
3527   /// A checker which white-lists certain expressions whose conversion
3528   /// to or from retainable type would otherwise be forbidden in ARC.
3529   class ARCCastChecker : public StmtVisitor<ARCCastChecker, ACCResult> {
3530     typedef StmtVisitor<ARCCastChecker, ACCResult> super;
3531 
3532     ASTContext &Context;
3533     ARCConversionTypeClass SourceClass;
3534     ARCConversionTypeClass TargetClass;
3535     bool Diagnose;
3536 
3537     static bool isCFType(QualType type) {
3538       // Someday this can use ns_bridged.  For now, it has to do this.
3539       return type->isCARCBridgableType();
3540     }
3541 
3542   public:
3543     ARCCastChecker(ASTContext &Context, ARCConversionTypeClass source,
3544                    ARCConversionTypeClass target, bool diagnose)
3545       : Context(Context), SourceClass(source), TargetClass(target),
3546         Diagnose(diagnose) {}
3547 
3548     using super::Visit;
3549     ACCResult Visit(Expr *e) {
3550       return super::Visit(e->IgnoreParens());
3551     }
3552 
3553     ACCResult VisitStmt(Stmt *s) {
3554       return ACC_invalid;
3555     }
3556 
3557     /// Null pointer constants can be casted however you please.
3558     ACCResult VisitExpr(Expr *e) {
3559       if (e->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
3560         return ACC_bottom;
3561       return ACC_invalid;
3562     }
3563 
3564     /// Objective-C string literals can be safely casted.
3565     ACCResult VisitObjCStringLiteral(ObjCStringLiteral *e) {
3566       // If we're casting to any retainable type, go ahead.  Global
3567       // strings are immune to retains, so this is bottom.
3568       if (isAnyRetainable(TargetClass)) return ACC_bottom;
3569 
3570       return ACC_invalid;
3571     }
3572 
3573     /// Look through certain implicit and explicit casts.
3574     ACCResult VisitCastExpr(CastExpr *e) {
3575       switch (e->getCastKind()) {
3576         case CK_NullToPointer:
3577           return ACC_bottom;
3578 
3579         case CK_NoOp:
3580         case CK_LValueToRValue:
3581         case CK_BitCast:
3582         case CK_CPointerToObjCPointerCast:
3583         case CK_BlockPointerToObjCPointerCast:
3584         case CK_AnyPointerToBlockPointerCast:
3585           return Visit(e->getSubExpr());
3586 
3587         default:
3588           return ACC_invalid;
3589       }
3590     }
3591 
3592     /// Look through unary extension.
3593     ACCResult VisitUnaryExtension(UnaryOperator *e) {
3594       return Visit(e->getSubExpr());
3595     }
3596 
3597     /// Ignore the LHS of a comma operator.
3598     ACCResult VisitBinComma(BinaryOperator *e) {
3599       return Visit(e->getRHS());
3600     }
3601 
3602     /// Conditional operators are okay if both sides are okay.
3603     ACCResult VisitConditionalOperator(ConditionalOperator *e) {
3604       ACCResult left = Visit(e->getTrueExpr());
3605       if (left == ACC_invalid) return ACC_invalid;
3606       return merge(left, Visit(e->getFalseExpr()));
3607     }
3608 
3609     /// Look through pseudo-objects.
3610     ACCResult VisitPseudoObjectExpr(PseudoObjectExpr *e) {
3611       // If we're getting here, we should always have a result.
3612       return Visit(e->getResultExpr());
3613     }
3614 
3615     /// Statement expressions are okay if their result expression is okay.
3616     ACCResult VisitStmtExpr(StmtExpr *e) {
3617       return Visit(e->getSubStmt()->body_back());
3618     }
3619 
3620     /// Some declaration references are okay.
3621     ACCResult VisitDeclRefExpr(DeclRefExpr *e) {
3622       VarDecl *var = dyn_cast<VarDecl>(e->getDecl());
3623       // References to global constants are okay.
3624       if (isAnyRetainable(TargetClass) &&
3625           isAnyRetainable(SourceClass) &&
3626           var &&
3627           !var->hasDefinition(Context) &&
3628           var->getType().isConstQualified()) {
3629 
3630         // In system headers, they can also be assumed to be immune to retains.
3631         // These are things like 'kCFStringTransformToLatin'.
3632         if (Context.getSourceManager().isInSystemHeader(var->getLocation()))
3633           return ACC_bottom;
3634 
3635         return ACC_plusZero;
3636       }
3637 
3638       // Nothing else.
3639       return ACC_invalid;
3640     }
3641 
3642     /// Some calls are okay.
3643     ACCResult VisitCallExpr(CallExpr *e) {
3644       if (FunctionDecl *fn = e->getDirectCallee())
3645         if (ACCResult result = checkCallToFunction(fn))
3646           return result;
3647 
3648       return super::VisitCallExpr(e);
3649     }
3650 
3651     ACCResult checkCallToFunction(FunctionDecl *fn) {
3652       // Require a CF*Ref return type.
3653       if (!isCFType(fn->getReturnType()))
3654         return ACC_invalid;
3655 
3656       if (!isAnyRetainable(TargetClass))
3657         return ACC_invalid;
3658 
3659       // Honor an explicit 'not retained' attribute.
3660       if (fn->hasAttr<CFReturnsNotRetainedAttr>())
3661         return ACC_plusZero;
3662 
3663       // Honor an explicit 'retained' attribute, except that for
3664       // now we're not going to permit implicit handling of +1 results,
3665       // because it's a bit frightening.
3666       if (fn->hasAttr<CFReturnsRetainedAttr>())
3667         return Diagnose ? ACC_plusOne
3668                         : ACC_invalid; // ACC_plusOne if we start accepting this
3669 
3670       // Recognize this specific builtin function, which is used by CFSTR.
3671       unsigned builtinID = fn->getBuiltinID();
3672       if (builtinID == Builtin::BI__builtin___CFStringMakeConstantString)
3673         return ACC_bottom;
3674 
3675       // Otherwise, don't do anything implicit with an unaudited function.
3676       if (!fn->hasAttr<CFAuditedTransferAttr>())
3677         return ACC_invalid;
3678 
3679       // Otherwise, it's +0 unless it follows the create convention.
3680       if (ento::coreFoundation::followsCreateRule(fn))
3681         return Diagnose ? ACC_plusOne
3682                         : ACC_invalid; // ACC_plusOne if we start accepting this
3683 
3684       return ACC_plusZero;
3685     }
3686 
3687     ACCResult VisitObjCMessageExpr(ObjCMessageExpr *e) {
3688       return checkCallToMethod(e->getMethodDecl());
3689     }
3690 
3691     ACCResult VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *e) {
3692       ObjCMethodDecl *method;
3693       if (e->isExplicitProperty())
3694         method = e->getExplicitProperty()->getGetterMethodDecl();
3695       else
3696         method = e->getImplicitPropertyGetter();
3697       return checkCallToMethod(method);
3698     }
3699 
3700     ACCResult checkCallToMethod(ObjCMethodDecl *method) {
3701       if (!method) return ACC_invalid;
3702 
3703       // Check for message sends to functions returning CF types.  We
3704       // just obey the Cocoa conventions with these, even though the
3705       // return type is CF.
3706       if (!isAnyRetainable(TargetClass) || !isCFType(method->getReturnType()))
3707         return ACC_invalid;
3708 
3709       // If the method is explicitly marked not-retained, it's +0.
3710       if (method->hasAttr<CFReturnsNotRetainedAttr>())
3711         return ACC_plusZero;
3712 
3713       // If the method is explicitly marked as returning retained, or its
3714       // selector follows a +1 Cocoa convention, treat it as +1.
3715       if (method->hasAttr<CFReturnsRetainedAttr>())
3716         return ACC_plusOne;
3717 
3718       switch (method->getSelector().getMethodFamily()) {
3719       case OMF_alloc:
3720       case OMF_copy:
3721       case OMF_mutableCopy:
3722       case OMF_new:
3723         return ACC_plusOne;
3724 
3725       default:
3726         // Otherwise, treat it as +0.
3727         return ACC_plusZero;
3728       }
3729     }
3730   };
3731 } // end anonymous namespace
3732 
3733 bool Sema::isKnownName(StringRef name) {
3734   if (name.empty())
3735     return false;
3736   LookupResult R(*this, &Context.Idents.get(name), SourceLocation(),
3737                  Sema::LookupOrdinaryName);
3738   return LookupName(R, TUScope, false);
3739 }
3740 
3741 template <typename DiagBuilderT>
3742 static void addFixitForObjCARCConversion(
3743     Sema &S, DiagBuilderT &DiagB, Sema::CheckedConversionKind CCK,
3744     SourceLocation afterLParen, QualType castType, Expr *castExpr,
3745     Expr *realCast, const char *bridgeKeyword, const char *CFBridgeName) {
3746   // We handle C-style and implicit casts here.
3747   switch (CCK) {
3748   case Sema::CCK_ImplicitConversion:
3749   case Sema::CCK_ForBuiltinOverloadedOp:
3750   case Sema::CCK_CStyleCast:
3751   case Sema::CCK_OtherCast:
3752     break;
3753   case Sema::CCK_FunctionalCast:
3754     return;
3755   }
3756 
3757   if (CFBridgeName) {
3758     if (CCK == Sema::CCK_OtherCast) {
3759       if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
3760         SourceRange range(NCE->getOperatorLoc(),
3761                           NCE->getAngleBrackets().getEnd());
3762         SmallString<32> BridgeCall;
3763 
3764         SourceManager &SM = S.getSourceManager();
3765         char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
3766         if (Lexer::isIdentifierBodyChar(PrevChar, S.getLangOpts()))
3767           BridgeCall += ' ';
3768 
3769         BridgeCall += CFBridgeName;
3770         DiagB.AddFixItHint(FixItHint::CreateReplacement(range, BridgeCall));
3771       }
3772       return;
3773     }
3774     Expr *castedE = castExpr;
3775     if (CStyleCastExpr *CCE = dyn_cast<CStyleCastExpr>(castedE))
3776       castedE = CCE->getSubExpr();
3777     castedE = castedE->IgnoreImpCasts();
3778     SourceRange range = castedE->getSourceRange();
3779 
3780     SmallString<32> BridgeCall;
3781 
3782     SourceManager &SM = S.getSourceManager();
3783     char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
3784     if (Lexer::isIdentifierBodyChar(PrevChar, S.getLangOpts()))
3785       BridgeCall += ' ';
3786 
3787     BridgeCall += CFBridgeName;
3788 
3789     if (isa<ParenExpr>(castedE)) {
3790       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3791                          BridgeCall));
3792     } else {
3793       BridgeCall += '(';
3794       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3795                                                     BridgeCall));
3796       DiagB.AddFixItHint(FixItHint::CreateInsertion(
3797                                        S.getLocForEndOfToken(range.getEnd()),
3798                                        ")"));
3799     }
3800     return;
3801   }
3802 
3803   if (CCK == Sema::CCK_CStyleCast) {
3804     DiagB.AddFixItHint(FixItHint::CreateInsertion(afterLParen, bridgeKeyword));
3805   } else if (CCK == Sema::CCK_OtherCast) {
3806     if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
3807       std::string castCode = "(";
3808       castCode += bridgeKeyword;
3809       castCode += castType.getAsString();
3810       castCode += ")";
3811       SourceRange Range(NCE->getOperatorLoc(),
3812                         NCE->getAngleBrackets().getEnd());
3813       DiagB.AddFixItHint(FixItHint::CreateReplacement(Range, castCode));
3814     }
3815   } else {
3816     std::string castCode = "(";
3817     castCode += bridgeKeyword;
3818     castCode += castType.getAsString();
3819     castCode += ")";
3820     Expr *castedE = castExpr->IgnoreImpCasts();
3821     SourceRange range = castedE->getSourceRange();
3822     if (isa<ParenExpr>(castedE)) {
3823       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3824                          castCode));
3825     } else {
3826       castCode += "(";
3827       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3828                                                     castCode));
3829       DiagB.AddFixItHint(FixItHint::CreateInsertion(
3830                                        S.getLocForEndOfToken(range.getEnd()),
3831                                        ")"));
3832     }
3833   }
3834 }
3835 
3836 template <typename T>
3837 static inline T *getObjCBridgeAttr(const TypedefType *TD) {
3838   TypedefNameDecl *TDNDecl = TD->getDecl();
3839   QualType QT = TDNDecl->getUnderlyingType();
3840   if (QT->isPointerType()) {
3841     QT = QT->getPointeeType();
3842     if (const RecordType *RT = QT->getAs<RecordType>())
3843       if (RecordDecl *RD = RT->getDecl()->getMostRecentDecl())
3844         return RD->getAttr<T>();
3845   }
3846   return nullptr;
3847 }
3848 
3849 static ObjCBridgeRelatedAttr *ObjCBridgeRelatedAttrFromType(QualType T,
3850                                                             TypedefNameDecl *&TDNDecl) {
3851   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
3852     TDNDecl = TD->getDecl();
3853     if (ObjCBridgeRelatedAttr *ObjCBAttr =
3854         getObjCBridgeAttr<ObjCBridgeRelatedAttr>(TD))
3855       return ObjCBAttr;
3856     T = TDNDecl->getUnderlyingType();
3857   }
3858   return nullptr;
3859 }
3860 
3861 static void
3862 diagnoseObjCARCConversion(Sema &S, SourceRange castRange,
3863                           QualType castType, ARCConversionTypeClass castACTC,
3864                           Expr *castExpr, Expr *realCast,
3865                           ARCConversionTypeClass exprACTC,
3866                           Sema::CheckedConversionKind CCK) {
3867   SourceLocation loc =
3868     (castRange.isValid() ? castRange.getBegin() : castExpr->getExprLoc());
3869 
3870   if (S.makeUnavailableInSystemHeader(loc,
3871                                  UnavailableAttr::IR_ARCForbiddenConversion))
3872     return;
3873 
3874   QualType castExprType = castExpr->getType();
3875   // Defer emitting a diagnostic for bridge-related casts; that will be
3876   // handled by CheckObjCBridgeRelatedConversions.
3877   TypedefNameDecl *TDNDecl = nullptr;
3878   if ((castACTC == ACTC_coreFoundation &&  exprACTC == ACTC_retainable &&
3879        ObjCBridgeRelatedAttrFromType(castType, TDNDecl)) ||
3880       (exprACTC == ACTC_coreFoundation && castACTC == ACTC_retainable &&
3881        ObjCBridgeRelatedAttrFromType(castExprType, TDNDecl)))
3882     return;
3883 
3884   unsigned srcKind = 0;
3885   switch (exprACTC) {
3886   case ACTC_none:
3887   case ACTC_coreFoundation:
3888   case ACTC_voidPtr:
3889     srcKind = (castExprType->isPointerType() ? 1 : 0);
3890     break;
3891   case ACTC_retainable:
3892     srcKind = (castExprType->isBlockPointerType() ? 2 : 3);
3893     break;
3894   case ACTC_indirectRetainable:
3895     srcKind = 4;
3896     break;
3897   }
3898 
3899   // Check whether this could be fixed with a bridge cast.
3900   SourceLocation afterLParen = S.getLocForEndOfToken(castRange.getBegin());
3901   SourceLocation noteLoc = afterLParen.isValid() ? afterLParen : loc;
3902 
3903   unsigned convKindForDiag = Sema::isCast(CCK) ? 0 : 1;
3904 
3905   // Bridge from an ARC type to a CF type.
3906   if (castACTC == ACTC_retainable && isAnyRetainable(exprACTC)) {
3907 
3908     S.Diag(loc, diag::err_arc_cast_requires_bridge)
3909       << convKindForDiag
3910       << 2 // of C pointer type
3911       << castExprType
3912       << unsigned(castType->isBlockPointerType()) // to ObjC|block type
3913       << castType
3914       << castRange
3915       << castExpr->getSourceRange();
3916     bool br = S.isKnownName("CFBridgingRelease");
3917     ACCResult CreateRule =
3918       ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
3919     assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
3920     if (CreateRule != ACC_plusOne)
3921     {
3922       auto DiagB = (CCK != Sema::CCK_OtherCast)
3923                        ? S.Diag(noteLoc, diag::note_arc_bridge)
3924                        : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
3925 
3926       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3927                                    castType, castExpr, realCast, "__bridge ",
3928                                    nullptr);
3929     }
3930     if (CreateRule != ACC_plusZero)
3931     {
3932       auto DiagB = (CCK == Sema::CCK_OtherCast && !br)
3933                        ? S.Diag(noteLoc, diag::note_arc_cstyle_bridge_transfer)
3934                              << castExprType
3935                        : S.Diag(br ? castExpr->getExprLoc() : noteLoc,
3936                                 diag::note_arc_bridge_transfer)
3937                              << castExprType << br;
3938 
3939       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3940                                    castType, castExpr, realCast, "__bridge_transfer ",
3941                                    br ? "CFBridgingRelease" : nullptr);
3942     }
3943 
3944     return;
3945   }
3946 
3947   // Bridge from a CF type to an ARC type.
3948   if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC)) {
3949     bool br = S.isKnownName("CFBridgingRetain");
3950     S.Diag(loc, diag::err_arc_cast_requires_bridge)
3951       << convKindForDiag
3952       << unsigned(castExprType->isBlockPointerType()) // of ObjC|block type
3953       << castExprType
3954       << 2 // to C pointer type
3955       << castType
3956       << castRange
3957       << castExpr->getSourceRange();
3958     ACCResult CreateRule =
3959       ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
3960     assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
3961     if (CreateRule != ACC_plusOne)
3962     {
3963       auto DiagB = (CCK != Sema::CCK_OtherCast)
3964                        ? S.Diag(noteLoc, diag::note_arc_bridge)
3965                        : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
3966       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3967                                    castType, castExpr, realCast, "__bridge ",
3968                                    nullptr);
3969     }
3970     if (CreateRule != ACC_plusZero)
3971     {
3972       auto DiagB = (CCK == Sema::CCK_OtherCast && !br)
3973                        ? S.Diag(noteLoc, diag::note_arc_cstyle_bridge_retained)
3974                              << castType
3975                        : S.Diag(br ? castExpr->getExprLoc() : noteLoc,
3976                                 diag::note_arc_bridge_retained)
3977                              << castType << br;
3978 
3979       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3980                                    castType, castExpr, realCast, "__bridge_retained ",
3981                                    br ? "CFBridgingRetain" : nullptr);
3982     }
3983 
3984     return;
3985   }
3986 
3987   S.Diag(loc, diag::err_arc_mismatched_cast)
3988     << !convKindForDiag
3989     << srcKind << castExprType << castType
3990     << castRange << castExpr->getSourceRange();
3991 }
3992 
3993 template <typename TB>
3994 static bool CheckObjCBridgeNSCast(Sema &S, QualType castType, Expr *castExpr,
3995                                   bool &HadTheAttribute, bool warn) {
3996   QualType T = castExpr->getType();
3997   HadTheAttribute = false;
3998   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
3999     TypedefNameDecl *TDNDecl = TD->getDecl();
4000     if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
4001       if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
4002         HadTheAttribute = true;
4003         if (Parm->isStr("id"))
4004           return true;
4005 
4006         NamedDecl *Target = nullptr;
4007         // Check for an existing type with this name.
4008         LookupResult R(S, DeclarationName(Parm), SourceLocation(),
4009                        Sema::LookupOrdinaryName);
4010         if (S.LookupName(R, S.TUScope)) {
4011           Target = R.getFoundDecl();
4012           if (Target && isa<ObjCInterfaceDecl>(Target)) {
4013             ObjCInterfaceDecl *ExprClass = cast<ObjCInterfaceDecl>(Target);
4014             if (const ObjCObjectPointerType *InterfacePointerType =
4015                   castType->getAsObjCInterfacePointerType()) {
4016               ObjCInterfaceDecl *CastClass
4017                 = InterfacePointerType->getObjectType()->getInterface();
4018               if ((CastClass == ExprClass) ||
4019                   (CastClass && CastClass->isSuperClassOf(ExprClass)))
4020                 return true;
4021               if (warn)
4022                 S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
4023                     << T << Target->getName() << castType->getPointeeType();
4024               return false;
4025             } else if (castType->isObjCIdType() ||
4026                        (S.Context.ObjCObjectAdoptsQTypeProtocols(
4027                           castType, ExprClass)))
4028               // ok to cast to 'id'.
4029               // casting to id<p-list> is ok if bridge type adopts all of
4030               // p-list protocols.
4031               return true;
4032             else {
4033               if (warn) {
4034                 S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
4035                     << T << Target->getName() << castType;
4036                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4037                 S.Diag(Target->getBeginLoc(), diag::note_declared_at);
4038               }
4039               return false;
4040            }
4041           }
4042         } else if (!castType->isObjCIdType()) {
4043           S.Diag(castExpr->getBeginLoc(),
4044                  diag::err_objc_cf_bridged_not_interface)
4045               << castExpr->getType() << Parm;
4046           S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4047           if (Target)
4048             S.Diag(Target->getBeginLoc(), diag::note_declared_at);
4049         }
4050         return true;
4051       }
4052       return false;
4053     }
4054     T = TDNDecl->getUnderlyingType();
4055   }
4056   return true;
4057 }
4058 
4059 template <typename TB>
4060 static bool CheckObjCBridgeCFCast(Sema &S, QualType castType, Expr *castExpr,
4061                                   bool &HadTheAttribute, bool warn) {
4062   QualType T = castType;
4063   HadTheAttribute = false;
4064   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
4065     TypedefNameDecl *TDNDecl = TD->getDecl();
4066     if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
4067       if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
4068         HadTheAttribute = true;
4069         if (Parm->isStr("id"))
4070           return true;
4071 
4072         NamedDecl *Target = nullptr;
4073         // Check for an existing type with this name.
4074         LookupResult R(S, DeclarationName(Parm), SourceLocation(),
4075                        Sema::LookupOrdinaryName);
4076         if (S.LookupName(R, S.TUScope)) {
4077           Target = R.getFoundDecl();
4078           if (Target && isa<ObjCInterfaceDecl>(Target)) {
4079             ObjCInterfaceDecl *CastClass = cast<ObjCInterfaceDecl>(Target);
4080             if (const ObjCObjectPointerType *InterfacePointerType =
4081                   castExpr->getType()->getAsObjCInterfacePointerType()) {
4082               ObjCInterfaceDecl *ExprClass
4083                 = InterfacePointerType->getObjectType()->getInterface();
4084               if ((CastClass == ExprClass) ||
4085                   (ExprClass && CastClass->isSuperClassOf(ExprClass)))
4086                 return true;
4087               if (warn) {
4088                 S.Diag(castExpr->getBeginLoc(),
4089                        diag::warn_objc_invalid_bridge_to_cf)
4090                     << castExpr->getType()->getPointeeType() << T;
4091                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4092               }
4093               return false;
4094             } else if (castExpr->getType()->isObjCIdType() ||
4095                        (S.Context.QIdProtocolsAdoptObjCObjectProtocols(
4096                           castExpr->getType(), CastClass)))
4097               // ok to cast an 'id' expression to a CFtype.
4098               // ok to cast an 'id<plist>' expression to CFtype provided plist
4099               // adopts all of CFtype's ObjetiveC's class plist.
4100               return true;
4101             else {
4102               if (warn) {
4103                 S.Diag(castExpr->getBeginLoc(),
4104                        diag::warn_objc_invalid_bridge_to_cf)
4105                     << castExpr->getType() << castType;
4106                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4107                 S.Diag(Target->getBeginLoc(), diag::note_declared_at);
4108               }
4109               return false;
4110             }
4111           }
4112         }
4113         S.Diag(castExpr->getBeginLoc(),
4114                diag::err_objc_ns_bridged_invalid_cfobject)
4115             << castExpr->getType() << castType;
4116         S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4117         if (Target)
4118           S.Diag(Target->getBeginLoc(), diag::note_declared_at);
4119         return true;
4120       }
4121       return false;
4122     }
4123     T = TDNDecl->getUnderlyingType();
4124   }
4125   return true;
4126 }
4127 
4128 void Sema::CheckTollFreeBridgeCast(QualType castType, Expr *castExpr) {
4129   if (!getLangOpts().ObjC)
4130     return;
4131   // warn in presence of __bridge casting to or from a toll free bridge cast.
4132   ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExpr->getType());
4133   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
4134   if (castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) {
4135     bool HasObjCBridgeAttr;
4136     bool ObjCBridgeAttrWillNotWarn =
4137       CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
4138                                             false);
4139     if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
4140       return;
4141     bool HasObjCBridgeMutableAttr;
4142     bool ObjCBridgeMutableAttrWillNotWarn =
4143       CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
4144                                                    HasObjCBridgeMutableAttr, false);
4145     if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
4146       return;
4147 
4148     if (HasObjCBridgeAttr)
4149       CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
4150                                             true);
4151     else if (HasObjCBridgeMutableAttr)
4152       CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
4153                                                    HasObjCBridgeMutableAttr, true);
4154   }
4155   else if (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable) {
4156     bool HasObjCBridgeAttr;
4157     bool ObjCBridgeAttrWillNotWarn =
4158       CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
4159                                             false);
4160     if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
4161       return;
4162     bool HasObjCBridgeMutableAttr;
4163     bool ObjCBridgeMutableAttrWillNotWarn =
4164       CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
4165                                                    HasObjCBridgeMutableAttr, false);
4166     if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
4167       return;
4168 
4169     if (HasObjCBridgeAttr)
4170       CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
4171                                             true);
4172     else if (HasObjCBridgeMutableAttr)
4173       CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
4174                                                    HasObjCBridgeMutableAttr, true);
4175   }
4176 }
4177 
4178 void Sema::CheckObjCBridgeRelatedCast(QualType castType, Expr *castExpr) {
4179   QualType SrcType = castExpr->getType();
4180   if (ObjCPropertyRefExpr *PRE = dyn_cast<ObjCPropertyRefExpr>(castExpr)) {
4181     if (PRE->isExplicitProperty()) {
4182       if (ObjCPropertyDecl *PDecl = PRE->getExplicitProperty())
4183         SrcType = PDecl->getType();
4184     }
4185     else if (PRE->isImplicitProperty()) {
4186       if (ObjCMethodDecl *Getter = PRE->getImplicitPropertyGetter())
4187         SrcType = Getter->getReturnType();
4188     }
4189   }
4190 
4191   ARCConversionTypeClass srcExprACTC = classifyTypeForARCConversion(SrcType);
4192   ARCConversionTypeClass castExprACTC = classifyTypeForARCConversion(castType);
4193   if (srcExprACTC != ACTC_retainable || castExprACTC != ACTC_coreFoundation)
4194     return;
4195   CheckObjCBridgeRelatedConversions(castExpr->getBeginLoc(), castType, SrcType,
4196                                     castExpr);
4197 }
4198 
4199 bool Sema::CheckTollFreeBridgeStaticCast(QualType castType, Expr *castExpr,
4200                                          CastKind &Kind) {
4201   if (!getLangOpts().ObjC)
4202     return false;
4203   ARCConversionTypeClass exprACTC =
4204     classifyTypeForARCConversion(castExpr->getType());
4205   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
4206   if ((castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) ||
4207       (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable)) {
4208     CheckTollFreeBridgeCast(castType, castExpr);
4209     Kind = (castACTC == ACTC_coreFoundation) ? CK_BitCast
4210                                              : CK_CPointerToObjCPointerCast;
4211     return true;
4212   }
4213   return false;
4214 }
4215 
4216 bool Sema::checkObjCBridgeRelatedComponents(SourceLocation Loc,
4217                                             QualType DestType, QualType SrcType,
4218                                             ObjCInterfaceDecl *&RelatedClass,
4219                                             ObjCMethodDecl *&ClassMethod,
4220                                             ObjCMethodDecl *&InstanceMethod,
4221                                             TypedefNameDecl *&TDNDecl,
4222                                             bool CfToNs, bool Diagnose) {
4223   QualType T = CfToNs ? SrcType : DestType;
4224   ObjCBridgeRelatedAttr *ObjCBAttr = ObjCBridgeRelatedAttrFromType(T, TDNDecl);
4225   if (!ObjCBAttr)
4226     return false;
4227 
4228   IdentifierInfo *RCId = ObjCBAttr->getRelatedClass();
4229   IdentifierInfo *CMId = ObjCBAttr->getClassMethod();
4230   IdentifierInfo *IMId = ObjCBAttr->getInstanceMethod();
4231   if (!RCId)
4232     return false;
4233   NamedDecl *Target = nullptr;
4234   // Check for an existing type with this name.
4235   LookupResult R(*this, DeclarationName(RCId), SourceLocation(),
4236                  Sema::LookupOrdinaryName);
4237   if (!LookupName(R, TUScope)) {
4238     if (Diagnose) {
4239       Diag(Loc, diag::err_objc_bridged_related_invalid_class) << RCId
4240             << SrcType << DestType;
4241       Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4242     }
4243     return false;
4244   }
4245   Target = R.getFoundDecl();
4246   if (Target && isa<ObjCInterfaceDecl>(Target))
4247     RelatedClass = cast<ObjCInterfaceDecl>(Target);
4248   else {
4249     if (Diagnose) {
4250       Diag(Loc, diag::err_objc_bridged_related_invalid_class_name) << RCId
4251             << SrcType << DestType;
4252       Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4253       if (Target)
4254         Diag(Target->getBeginLoc(), diag::note_declared_at);
4255     }
4256     return false;
4257   }
4258 
4259   // Check for an existing class method with the given selector name.
4260   if (CfToNs && CMId) {
4261     Selector Sel = Context.Selectors.getUnarySelector(CMId);
4262     ClassMethod = RelatedClass->lookupMethod(Sel, false);
4263     if (!ClassMethod) {
4264       if (Diagnose) {
4265         Diag(Loc, diag::err_objc_bridged_related_known_method)
4266               << SrcType << DestType << Sel << false;
4267         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4268       }
4269       return false;
4270     }
4271   }
4272 
4273   // Check for an existing instance method with the given selector name.
4274   if (!CfToNs && IMId) {
4275     Selector Sel = Context.Selectors.getNullarySelector(IMId);
4276     InstanceMethod = RelatedClass->lookupMethod(Sel, true);
4277     if (!InstanceMethod) {
4278       if (Diagnose) {
4279         Diag(Loc, diag::err_objc_bridged_related_known_method)
4280               << SrcType << DestType << Sel << true;
4281         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4282       }
4283       return false;
4284     }
4285   }
4286   return true;
4287 }
4288 
4289 bool
4290 Sema::CheckObjCBridgeRelatedConversions(SourceLocation Loc,
4291                                         QualType DestType, QualType SrcType,
4292                                         Expr *&SrcExpr, bool Diagnose) {
4293   ARCConversionTypeClass rhsExprACTC = classifyTypeForARCConversion(SrcType);
4294   ARCConversionTypeClass lhsExprACTC = classifyTypeForARCConversion(DestType);
4295   bool CfToNs = (rhsExprACTC == ACTC_coreFoundation && lhsExprACTC == ACTC_retainable);
4296   bool NsToCf = (rhsExprACTC == ACTC_retainable && lhsExprACTC == ACTC_coreFoundation);
4297   if (!CfToNs && !NsToCf)
4298     return false;
4299 
4300   ObjCInterfaceDecl *RelatedClass;
4301   ObjCMethodDecl *ClassMethod = nullptr;
4302   ObjCMethodDecl *InstanceMethod = nullptr;
4303   TypedefNameDecl *TDNDecl = nullptr;
4304   if (!checkObjCBridgeRelatedComponents(Loc, DestType, SrcType, RelatedClass,
4305                                         ClassMethod, InstanceMethod, TDNDecl,
4306                                         CfToNs, Diagnose))
4307     return false;
4308 
4309   if (CfToNs) {
4310     // Implicit conversion from CF to ObjC object is needed.
4311     if (ClassMethod) {
4312       if (Diagnose) {
4313         std::string ExpressionString = "[";
4314         ExpressionString += RelatedClass->getNameAsString();
4315         ExpressionString += " ";
4316         ExpressionString += ClassMethod->getSelector().getAsString();
4317         SourceLocation SrcExprEndLoc =
4318             getLocForEndOfToken(SrcExpr->getEndLoc());
4319         // Provide a fixit: [RelatedClass ClassMethod SrcExpr]
4320         Diag(Loc, diag::err_objc_bridged_related_known_method)
4321             << SrcType << DestType << ClassMethod->getSelector() << false
4322             << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(),
4323                                           ExpressionString)
4324             << FixItHint::CreateInsertion(SrcExprEndLoc, "]");
4325         Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
4326         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4327 
4328         QualType receiverType = Context.getObjCInterfaceType(RelatedClass);
4329         // Argument.
4330         Expr *args[] = { SrcExpr };
4331         ExprResult msg = BuildClassMessageImplicit(receiverType, false,
4332                                       ClassMethod->getLocation(),
4333                                       ClassMethod->getSelector(), ClassMethod,
4334                                       MultiExprArg(args, 1));
4335         SrcExpr = msg.get();
4336       }
4337       return true;
4338     }
4339   }
4340   else {
4341     // Implicit conversion from ObjC type to CF object is needed.
4342     if (InstanceMethod) {
4343       if (Diagnose) {
4344         std::string ExpressionString;
4345         SourceLocation SrcExprEndLoc =
4346             getLocForEndOfToken(SrcExpr->getEndLoc());
4347         if (InstanceMethod->isPropertyAccessor())
4348           if (const ObjCPropertyDecl *PDecl =
4349                   InstanceMethod->findPropertyDecl()) {
4350             // fixit: ObjectExpr.propertyname when it is  aproperty accessor.
4351             ExpressionString = ".";
4352             ExpressionString += PDecl->getNameAsString();
4353             Diag(Loc, diag::err_objc_bridged_related_known_method)
4354                 << SrcType << DestType << InstanceMethod->getSelector() << true
4355                 << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
4356           }
4357         if (ExpressionString.empty()) {
4358           // Provide a fixit: [ObjectExpr InstanceMethod]
4359           ExpressionString = " ";
4360           ExpressionString += InstanceMethod->getSelector().getAsString();
4361           ExpressionString += "]";
4362 
4363           Diag(Loc, diag::err_objc_bridged_related_known_method)
4364               << SrcType << DestType << InstanceMethod->getSelector() << true
4365               << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(), "[")
4366               << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
4367         }
4368         Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
4369         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4370 
4371         ExprResult msg =
4372           BuildInstanceMessageImplicit(SrcExpr, SrcType,
4373                                        InstanceMethod->getLocation(),
4374                                        InstanceMethod->getSelector(),
4375                                        InstanceMethod, None);
4376         SrcExpr = msg.get();
4377       }
4378       return true;
4379     }
4380   }
4381   return false;
4382 }
4383 
4384 Sema::ARCConversionResult
4385 Sema::CheckObjCConversion(SourceRange castRange, QualType castType,
4386                           Expr *&castExpr, CheckedConversionKind CCK,
4387                           bool Diagnose, bool DiagnoseCFAudited,
4388                           BinaryOperatorKind Opc) {
4389   QualType castExprType = castExpr->getType();
4390 
4391   // For the purposes of the classification, we assume reference types
4392   // will bind to temporaries.
4393   QualType effCastType = castType;
4394   if (const ReferenceType *ref = castType->getAs<ReferenceType>())
4395     effCastType = ref->getPointeeType();
4396 
4397   ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExprType);
4398   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(effCastType);
4399   if (exprACTC == castACTC) {
4400     // Check for viability and report error if casting an rvalue to a
4401     // life-time qualifier.
4402     if (castACTC == ACTC_retainable &&
4403         (CCK == CCK_CStyleCast || CCK == CCK_OtherCast) &&
4404         castType != castExprType) {
4405       const Type *DT = castType.getTypePtr();
4406       QualType QDT = castType;
4407       // We desugar some types but not others. We ignore those
4408       // that cannot happen in a cast; i.e. auto, and those which
4409       // should not be de-sugared; i.e typedef.
4410       if (const ParenType *PT = dyn_cast<ParenType>(DT))
4411         QDT = PT->desugar();
4412       else if (const TypeOfType *TP = dyn_cast<TypeOfType>(DT))
4413         QDT = TP->desugar();
4414       else if (const AttributedType *AT = dyn_cast<AttributedType>(DT))
4415         QDT = AT->desugar();
4416       if (QDT != castType &&
4417           QDT.getObjCLifetime() !=  Qualifiers::OCL_None) {
4418         if (Diagnose) {
4419           SourceLocation loc = (castRange.isValid() ? castRange.getBegin()
4420                                                     : castExpr->getExprLoc());
4421           Diag(loc, diag::err_arc_nolifetime_behavior);
4422         }
4423         return ACR_error;
4424       }
4425     }
4426     return ACR_okay;
4427   }
4428 
4429   // The life-time qualifier cast check above is all we need for ObjCWeak.
4430   // ObjCAutoRefCount has more restrictions on what is legal.
4431   if (!getLangOpts().ObjCAutoRefCount)
4432     return ACR_okay;
4433 
4434   if (isAnyCLike(exprACTC) && isAnyCLike(castACTC)) return ACR_okay;
4435 
4436   // Allow all of these types to be cast to integer types (but not
4437   // vice-versa).
4438   if (castACTC == ACTC_none && castType->isIntegralType(Context))
4439     return ACR_okay;
4440 
4441   // Allow casts between pointers to lifetime types (e.g., __strong id*)
4442   // and pointers to void (e.g., cv void *). Casting from void* to lifetime*
4443   // must be explicit.
4444   if (exprACTC == ACTC_indirectRetainable && castACTC == ACTC_voidPtr)
4445     return ACR_okay;
4446   if (castACTC == ACTC_indirectRetainable && exprACTC == ACTC_voidPtr &&
4447       isCast(CCK))
4448     return ACR_okay;
4449 
4450   switch (ARCCastChecker(Context, exprACTC, castACTC, false).Visit(castExpr)) {
4451   // For invalid casts, fall through.
4452   case ACC_invalid:
4453     break;
4454 
4455   // Do nothing for both bottom and +0.
4456   case ACC_bottom:
4457   case ACC_plusZero:
4458     return ACR_okay;
4459 
4460   // If the result is +1, consume it here.
4461   case ACC_plusOne:
4462     castExpr = ImplicitCastExpr::Create(Context, castExpr->getType(),
4463                                         CK_ARCConsumeObject, castExpr, nullptr,
4464                                         VK_RValue, FPOptionsOverride());
4465     Cleanup.setExprNeedsCleanups(true);
4466     return ACR_okay;
4467   }
4468 
4469   // If this is a non-implicit cast from id or block type to a
4470   // CoreFoundation type, delay complaining in case the cast is used
4471   // in an acceptable context.
4472   if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC) && isCast(CCK))
4473     return ACR_unbridged;
4474 
4475   // Issue a diagnostic about a missing @-sign when implicit casting a cstring
4476   // to 'NSString *', instead of falling through to report a "bridge cast"
4477   // diagnostic.
4478   if (castACTC == ACTC_retainable && exprACTC == ACTC_none &&
4479       CheckConversionToObjCLiteral(castType, castExpr, Diagnose))
4480     return ACR_error;
4481 
4482   // Do not issue "bridge cast" diagnostic when implicit casting
4483   // a retainable object to a CF type parameter belonging to an audited
4484   // CF API function. Let caller issue a normal type mismatched diagnostic
4485   // instead.
4486   if ((!DiagnoseCFAudited || exprACTC != ACTC_retainable ||
4487        castACTC != ACTC_coreFoundation) &&
4488       !(exprACTC == ACTC_voidPtr && castACTC == ACTC_retainable &&
4489         (Opc == BO_NE || Opc == BO_EQ))) {
4490     if (Diagnose)
4491       diagnoseObjCARCConversion(*this, castRange, castType, castACTC, castExpr,
4492                                 castExpr, exprACTC, CCK);
4493     return ACR_error;
4494   }
4495   return ACR_okay;
4496 }
4497 
4498 /// Given that we saw an expression with the ARCUnbridgedCastTy
4499 /// placeholder type, complain bitterly.
4500 void Sema::diagnoseARCUnbridgedCast(Expr *e) {
4501   // We expect the spurious ImplicitCastExpr to already have been stripped.
4502   assert(!e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
4503   CastExpr *realCast = cast<CastExpr>(e->IgnoreParens());
4504 
4505   SourceRange castRange;
4506   QualType castType;
4507   CheckedConversionKind CCK;
4508 
4509   if (CStyleCastExpr *cast = dyn_cast<CStyleCastExpr>(realCast)) {
4510     castRange = SourceRange(cast->getLParenLoc(), cast->getRParenLoc());
4511     castType = cast->getTypeAsWritten();
4512     CCK = CCK_CStyleCast;
4513   } else if (ExplicitCastExpr *cast = dyn_cast<ExplicitCastExpr>(realCast)) {
4514     castRange = cast->getTypeInfoAsWritten()->getTypeLoc().getSourceRange();
4515     castType = cast->getTypeAsWritten();
4516     CCK = CCK_OtherCast;
4517   } else {
4518     llvm_unreachable("Unexpected ImplicitCastExpr");
4519   }
4520 
4521   ARCConversionTypeClass castACTC =
4522     classifyTypeForARCConversion(castType.getNonReferenceType());
4523 
4524   Expr *castExpr = realCast->getSubExpr();
4525   assert(classifyTypeForARCConversion(castExpr->getType()) == ACTC_retainable);
4526 
4527   diagnoseObjCARCConversion(*this, castRange, castType, castACTC,
4528                             castExpr, realCast, ACTC_retainable, CCK);
4529 }
4530 
4531 /// stripARCUnbridgedCast - Given an expression of ARCUnbridgedCast
4532 /// type, remove the placeholder cast.
4533 Expr *Sema::stripARCUnbridgedCast(Expr *e) {
4534   assert(e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
4535 
4536   if (ParenExpr *pe = dyn_cast<ParenExpr>(e)) {
4537     Expr *sub = stripARCUnbridgedCast(pe->getSubExpr());
4538     return new (Context) ParenExpr(pe->getLParen(), pe->getRParen(), sub);
4539   } else if (UnaryOperator *uo = dyn_cast<UnaryOperator>(e)) {
4540     assert(uo->getOpcode() == UO_Extension);
4541     Expr *sub = stripARCUnbridgedCast(uo->getSubExpr());
4542     return UnaryOperator::Create(Context, sub, UO_Extension, sub->getType(),
4543                                  sub->getValueKind(), sub->getObjectKind(),
4544                                  uo->getOperatorLoc(), false,
4545                                  CurFPFeatureOverrides());
4546   } else if (GenericSelectionExpr *gse = dyn_cast<GenericSelectionExpr>(e)) {
4547     assert(!gse->isResultDependent());
4548 
4549     unsigned n = gse->getNumAssocs();
4550     SmallVector<Expr *, 4> subExprs;
4551     SmallVector<TypeSourceInfo *, 4> subTypes;
4552     subExprs.reserve(n);
4553     subTypes.reserve(n);
4554     for (const GenericSelectionExpr::Association assoc : gse->associations()) {
4555       subTypes.push_back(assoc.getTypeSourceInfo());
4556       Expr *sub = assoc.getAssociationExpr();
4557       if (assoc.isSelected())
4558         sub = stripARCUnbridgedCast(sub);
4559       subExprs.push_back(sub);
4560     }
4561 
4562     return GenericSelectionExpr::Create(
4563         Context, gse->getGenericLoc(), gse->getControllingExpr(), subTypes,
4564         subExprs, gse->getDefaultLoc(), gse->getRParenLoc(),
4565         gse->containsUnexpandedParameterPack(), gse->getResultIndex());
4566   } else {
4567     assert(isa<ImplicitCastExpr>(e) && "bad form of unbridged cast!");
4568     return cast<ImplicitCastExpr>(e)->getSubExpr();
4569   }
4570 }
4571 
4572 bool Sema::CheckObjCARCUnavailableWeakConversion(QualType castType,
4573                                                  QualType exprType) {
4574   QualType canCastType =
4575     Context.getCanonicalType(castType).getUnqualifiedType();
4576   QualType canExprType =
4577     Context.getCanonicalType(exprType).getUnqualifiedType();
4578   if (isa<ObjCObjectPointerType>(canCastType) &&
4579       castType.getObjCLifetime() == Qualifiers::OCL_Weak &&
4580       canExprType->isObjCObjectPointerType()) {
4581     if (const ObjCObjectPointerType *ObjT =
4582         canExprType->getAs<ObjCObjectPointerType>())
4583       if (const ObjCInterfaceDecl *ObjI = ObjT->getInterfaceDecl())
4584         return !ObjI->isArcWeakrefUnavailable();
4585   }
4586   return true;
4587 }
4588 
4589 /// Look for an ObjCReclaimReturnedObject cast and destroy it.
4590 static Expr *maybeUndoReclaimObject(Expr *e) {
4591   Expr *curExpr = e, *prevExpr = nullptr;
4592 
4593   // Walk down the expression until we hit an implicit cast of kind
4594   // ARCReclaimReturnedObject or an Expr that is neither a Paren nor a Cast.
4595   while (true) {
4596     if (auto *pe = dyn_cast<ParenExpr>(curExpr)) {
4597       prevExpr = curExpr;
4598       curExpr = pe->getSubExpr();
4599       continue;
4600     }
4601 
4602     if (auto *ce = dyn_cast<CastExpr>(curExpr)) {
4603       if (auto *ice = dyn_cast<ImplicitCastExpr>(ce))
4604         if (ice->getCastKind() == CK_ARCReclaimReturnedObject) {
4605           if (!prevExpr)
4606             return ice->getSubExpr();
4607           if (auto *pe = dyn_cast<ParenExpr>(prevExpr))
4608             pe->setSubExpr(ice->getSubExpr());
4609           else
4610             cast<CastExpr>(prevExpr)->setSubExpr(ice->getSubExpr());
4611           return e;
4612         }
4613 
4614       prevExpr = curExpr;
4615       curExpr = ce->getSubExpr();
4616       continue;
4617     }
4618 
4619     // Break out of the loop if curExpr is neither a Paren nor a Cast.
4620     break;
4621   }
4622 
4623   return e;
4624 }
4625 
4626 ExprResult Sema::BuildObjCBridgedCast(SourceLocation LParenLoc,
4627                                       ObjCBridgeCastKind Kind,
4628                                       SourceLocation BridgeKeywordLoc,
4629                                       TypeSourceInfo *TSInfo,
4630                                       Expr *SubExpr) {
4631   ExprResult SubResult = UsualUnaryConversions(SubExpr);
4632   if (SubResult.isInvalid()) return ExprError();
4633   SubExpr = SubResult.get();
4634 
4635   QualType T = TSInfo->getType();
4636   QualType FromType = SubExpr->getType();
4637 
4638   CastKind CK;
4639 
4640   bool MustConsume = false;
4641   if (T->isDependentType() || SubExpr->isTypeDependent()) {
4642     // Okay: we'll build a dependent expression type.
4643     CK = CK_Dependent;
4644   } else if (T->isObjCARCBridgableType() && FromType->isCARCBridgableType()) {
4645     // Casting CF -> id
4646     CK = (T->isBlockPointerType() ? CK_AnyPointerToBlockPointerCast
4647                                   : CK_CPointerToObjCPointerCast);
4648     switch (Kind) {
4649     case OBC_Bridge:
4650       break;
4651 
4652     case OBC_BridgeRetained: {
4653       bool br = isKnownName("CFBridgingRelease");
4654       Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
4655         << 2
4656         << FromType
4657         << (T->isBlockPointerType()? 1 : 0)
4658         << T
4659         << SubExpr->getSourceRange()
4660         << Kind;
4661       Diag(BridgeKeywordLoc, diag::note_arc_bridge)
4662         << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge");
4663       Diag(BridgeKeywordLoc, diag::note_arc_bridge_transfer)
4664         << FromType << br
4665         << FixItHint::CreateReplacement(BridgeKeywordLoc,
4666                                         br ? "CFBridgingRelease "
4667                                            : "__bridge_transfer ");
4668 
4669       Kind = OBC_Bridge;
4670       break;
4671     }
4672 
4673     case OBC_BridgeTransfer:
4674       // We must consume the Objective-C object produced by the cast.
4675       MustConsume = true;
4676       break;
4677     }
4678   } else if (T->isCARCBridgableType() && FromType->isObjCARCBridgableType()) {
4679     // Okay: id -> CF
4680     CK = CK_BitCast;
4681     switch (Kind) {
4682     case OBC_Bridge:
4683       // Reclaiming a value that's going to be __bridge-casted to CF
4684       // is very dangerous, so we don't do it.
4685       SubExpr = maybeUndoReclaimObject(SubExpr);
4686       break;
4687 
4688     case OBC_BridgeRetained:
4689       // Produce the object before casting it.
4690       SubExpr = ImplicitCastExpr::Create(Context, FromType, CK_ARCProduceObject,
4691                                          SubExpr, nullptr, VK_RValue,
4692                                          FPOptionsOverride());
4693       break;
4694 
4695     case OBC_BridgeTransfer: {
4696       bool br = isKnownName("CFBridgingRetain");
4697       Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
4698         << (FromType->isBlockPointerType()? 1 : 0)
4699         << FromType
4700         << 2
4701         << T
4702         << SubExpr->getSourceRange()
4703         << Kind;
4704 
4705       Diag(BridgeKeywordLoc, diag::note_arc_bridge)
4706         << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge ");
4707       Diag(BridgeKeywordLoc, diag::note_arc_bridge_retained)
4708         << T << br
4709         << FixItHint::CreateReplacement(BridgeKeywordLoc,
4710                           br ? "CFBridgingRetain " : "__bridge_retained");
4711 
4712       Kind = OBC_Bridge;
4713       break;
4714     }
4715     }
4716   } else {
4717     Diag(LParenLoc, diag::err_arc_bridge_cast_incompatible)
4718       << FromType << T << Kind
4719       << SubExpr->getSourceRange()
4720       << TSInfo->getTypeLoc().getSourceRange();
4721     return ExprError();
4722   }
4723 
4724   Expr *Result = new (Context) ObjCBridgedCastExpr(LParenLoc, Kind, CK,
4725                                                    BridgeKeywordLoc,
4726                                                    TSInfo, SubExpr);
4727 
4728   if (MustConsume) {
4729     Cleanup.setExprNeedsCleanups(true);
4730     Result = ImplicitCastExpr::Create(Context, T, CK_ARCConsumeObject, Result,
4731                                       nullptr, VK_RValue, FPOptionsOverride());
4732   }
4733 
4734   return Result;
4735 }
4736 
4737 ExprResult Sema::ActOnObjCBridgedCast(Scope *S,
4738                                       SourceLocation LParenLoc,
4739                                       ObjCBridgeCastKind Kind,
4740                                       SourceLocation BridgeKeywordLoc,
4741                                       ParsedType Type,
4742                                       SourceLocation RParenLoc,
4743                                       Expr *SubExpr) {
4744   TypeSourceInfo *TSInfo = nullptr;
4745   QualType T = GetTypeFromParser(Type, &TSInfo);
4746   if (Kind == OBC_Bridge)
4747     CheckTollFreeBridgeCast(T, SubExpr);
4748   if (!TSInfo)
4749     TSInfo = Context.getTrivialTypeSourceInfo(T, LParenLoc);
4750   return BuildObjCBridgedCast(LParenLoc, Kind, BridgeKeywordLoc, TSInfo,
4751                               SubExpr);
4752 }
4753