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/Sema/SemaInternal.h"
14 #include "clang/AST/ASTContext.h"
15 #include "clang/AST/DeclObjC.h"
16 #include "clang/AST/ExprObjC.h"
17 #include "clang/AST/StmtVisitor.h"
18 #include "clang/AST/TypeLoc.h"
19 #include "clang/Analysis/DomainSpecific/CocoaConventions.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 "llvm/ADT/SmallString.h"
28 #include "llvm/Support/ConvertUTF.h"
29 
30 using namespace clang;
31 using namespace sema;
32 using llvm::makeArrayRef;
33 
34 ExprResult Sema::ParseObjCStringLiteral(SourceLocation *AtLocs,
35                                         ArrayRef<Expr *> Strings) {
36   // Most ObjC strings are formed out of a single piece.  However, we *can*
37   // have strings formed out of multiple @ strings with multiple pptokens in
38   // each one, e.g. @"foo" "bar" @"baz" "qux"   which need to be turned into one
39   // StringLiteral for ObjCStringLiteral to hold onto.
40   StringLiteral *S = cast<StringLiteral>(Strings[0]);
41 
42   // If we have a multi-part string, merge it all together.
43   if (Strings.size() != 1) {
44     // Concatenate objc strings.
45     SmallString<128> StrBuf;
46     SmallVector<SourceLocation, 8> StrLocs;
47 
48     for (Expr *E : Strings) {
49       S = cast<StringLiteral>(E);
50 
51       // ObjC strings can't be wide or UTF.
52       if (!S->isAscii()) {
53         Diag(S->getBeginLoc(), diag::err_cfstring_literal_not_string_constant)
54             << S->getSourceRange();
55         return true;
56       }
57 
58       // Append the string.
59       StrBuf += S->getString();
60 
61       // Get the locations of the string tokens.
62       StrLocs.append(S->tokloc_begin(), S->tokloc_end());
63     }
64 
65     // Create the aggregate string with the appropriate content and location
66     // information.
67     const ConstantArrayType *CAT = Context.getAsConstantArrayType(S->getType());
68     assert(CAT && "String literal not of constant array type!");
69     QualType StrTy = Context.getConstantArrayType(
70         CAT->getElementType(), llvm::APInt(32, StrBuf.size() + 1),
71         CAT->getSizeModifier(), CAT->getIndexTypeCVRQualifiers());
72     S = StringLiteral::Create(Context, StrBuf, StringLiteral::Ascii,
73                               /*Pascal=*/false, StrTy, &StrLocs[0],
74                               StrLocs.size());
75   }
76 
77   return BuildObjCStringLiteral(AtLocs[0], S);
78 }
79 
80 ExprResult Sema::BuildObjCStringLiteral(SourceLocation AtLoc, StringLiteral *S){
81   // Verify that this composite string is acceptable for ObjC strings.
82   if (CheckObjCString(S))
83     return true;
84 
85   // Initialize the constant string interface lazily. This assumes
86   // the NSString interface is seen in this translation unit. Note: We
87   // don't use NSConstantString, since the runtime team considers this
88   // interface private (even though it appears in the header files).
89   QualType Ty = Context.getObjCConstantStringInterface();
90   if (!Ty.isNull()) {
91     Ty = Context.getObjCObjectPointerType(Ty);
92   } else if (getLangOpts().NoConstantCFStrings) {
93     IdentifierInfo *NSIdent=nullptr;
94     std::string StringClass(getLangOpts().ObjCConstantStringClass);
95 
96     if (StringClass.empty())
97       NSIdent = &Context.Idents.get("NSConstantString");
98     else
99       NSIdent = &Context.Idents.get(StringClass);
100 
101     NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
102                                      LookupOrdinaryName);
103     if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
104       Context.setObjCConstantStringInterface(StrIF);
105       Ty = Context.getObjCConstantStringInterface();
106       Ty = Context.getObjCObjectPointerType(Ty);
107     } else {
108       // If there is no NSConstantString interface defined then treat this
109       // as error and recover from it.
110       Diag(S->getBeginLoc(), diag::err_no_nsconstant_string_class)
111           << NSIdent << S->getSourceRange();
112       Ty = Context.getObjCIdType();
113     }
114   } else {
115     IdentifierInfo *NSIdent = NSAPIObj->getNSClassId(NSAPI::ClassId_NSString);
116     NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
117                                      LookupOrdinaryName);
118     if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
119       Context.setObjCConstantStringInterface(StrIF);
120       Ty = Context.getObjCConstantStringInterface();
121       Ty = Context.getObjCObjectPointerType(Ty);
122     } else {
123       // If there is no NSString interface defined, implicitly declare
124       // a @class NSString; and use that instead. This is to make sure
125       // type of an NSString literal is represented correctly, instead of
126       // being an 'id' type.
127       Ty = Context.getObjCNSStringType();
128       if (Ty.isNull()) {
129         ObjCInterfaceDecl *NSStringIDecl =
130           ObjCInterfaceDecl::Create (Context,
131                                      Context.getTranslationUnitDecl(),
132                                      SourceLocation(), NSIdent,
133                                      nullptr, nullptr, SourceLocation());
134         Ty = Context.getObjCInterfaceType(NSStringIDecl);
135         Context.setObjCNSStringType(Ty);
136       }
137       Ty = Context.getObjCObjectPointerType(Ty);
138     }
139   }
140 
141   return new (Context) ObjCStringLiteral(S, Ty, AtLoc);
142 }
143 
144 /// Emits an error if the given method does not exist, or if the return
145 /// type is not an Objective-C object.
146 static bool validateBoxingMethod(Sema &S, SourceLocation Loc,
147                                  const ObjCInterfaceDecl *Class,
148                                  Selector Sel, const ObjCMethodDecl *Method) {
149   if (!Method) {
150     // FIXME: Is there a better way to avoid quotes than using getName()?
151     S.Diag(Loc, diag::err_undeclared_boxing_method) << Sel << Class->getName();
152     return false;
153   }
154 
155   // Make sure the return type is reasonable.
156   QualType ReturnType = Method->getReturnType();
157   if (!ReturnType->isObjCObjectPointerType()) {
158     S.Diag(Loc, diag::err_objc_literal_method_sig)
159       << Sel;
160     S.Diag(Method->getLocation(), diag::note_objc_literal_method_return)
161       << ReturnType;
162     return false;
163   }
164 
165   return true;
166 }
167 
168 /// Maps ObjCLiteralKind to NSClassIdKindKind
169 static NSAPI::NSClassIdKindKind ClassKindFromLiteralKind(
170                                             Sema::ObjCLiteralKind LiteralKind) {
171   switch (LiteralKind) {
172     case Sema::LK_Array:
173       return NSAPI::ClassId_NSArray;
174     case Sema::LK_Dictionary:
175       return NSAPI::ClassId_NSDictionary;
176     case Sema::LK_Numeric:
177       return NSAPI::ClassId_NSNumber;
178     case Sema::LK_String:
179       return NSAPI::ClassId_NSString;
180     case Sema::LK_Boxed:
181       return NSAPI::ClassId_NSValue;
182 
183     // there is no corresponding matching
184     // between LK_None/LK_Block and NSClassIdKindKind
185     case Sema::LK_Block:
186     case Sema::LK_None:
187       break;
188   }
189   llvm_unreachable("LiteralKind can't be converted into a ClassKind");
190 }
191 
192 /// Validates ObjCInterfaceDecl availability.
193 /// ObjCInterfaceDecl, used to create ObjC literals, should be defined
194 /// if clang not in a debugger mode.
195 static bool ValidateObjCLiteralInterfaceDecl(Sema &S, ObjCInterfaceDecl *Decl,
196                                             SourceLocation Loc,
197                                             Sema::ObjCLiteralKind LiteralKind) {
198   if (!Decl) {
199     NSAPI::NSClassIdKindKind Kind = ClassKindFromLiteralKind(LiteralKind);
200     IdentifierInfo *II = S.NSAPIObj->getNSClassId(Kind);
201     S.Diag(Loc, diag::err_undeclared_objc_literal_class)
202       << II->getName() << LiteralKind;
203     return false;
204   } else if (!Decl->hasDefinition() && !S.getLangOpts().DebuggerObjCLiteral) {
205     S.Diag(Loc, diag::err_undeclared_objc_literal_class)
206       << Decl->getName() << LiteralKind;
207     S.Diag(Decl->getLocation(), diag::note_forward_class);
208     return false;
209   }
210 
211   return true;
212 }
213 
214 /// Looks up ObjCInterfaceDecl of a given NSClassIdKindKind.
215 /// Used to create ObjC literals, such as NSDictionary (@{}),
216 /// NSArray (@[]) and Boxed Expressions (@())
217 static ObjCInterfaceDecl *LookupObjCInterfaceDeclForLiteral(Sema &S,
218                                             SourceLocation Loc,
219                                             Sema::ObjCLiteralKind LiteralKind) {
220   NSAPI::NSClassIdKindKind ClassKind = ClassKindFromLiteralKind(LiteralKind);
221   IdentifierInfo *II = S.NSAPIObj->getNSClassId(ClassKind);
222   NamedDecl *IF = S.LookupSingleName(S.TUScope, II, Loc,
223                                      Sema::LookupOrdinaryName);
224   ObjCInterfaceDecl *ID = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
225   if (!ID && S.getLangOpts().DebuggerObjCLiteral) {
226     ASTContext &Context = S.Context;
227     TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
228     ID = ObjCInterfaceDecl::Create (Context, TU, SourceLocation(), II,
229                                     nullptr, nullptr, SourceLocation());
230   }
231 
232   if (!ValidateObjCLiteralInterfaceDecl(S, ID, Loc, LiteralKind)) {
233     ID = nullptr;
234   }
235 
236   return ID;
237 }
238 
239 /// Retrieve the NSNumber factory method that should be used to create
240 /// an Objective-C literal for the given type.
241 static ObjCMethodDecl *getNSNumberFactoryMethod(Sema &S, SourceLocation Loc,
242                                                 QualType NumberType,
243                                                 bool isLiteral = false,
244                                                 SourceRange R = SourceRange()) {
245   Optional<NSAPI::NSNumberLiteralMethodKind> Kind =
246       S.NSAPIObj->getNSNumberFactoryMethodKind(NumberType);
247 
248   if (!Kind) {
249     if (isLiteral) {
250       S.Diag(Loc, diag::err_invalid_nsnumber_type)
251         << NumberType << R;
252     }
253     return nullptr;
254   }
255 
256   // If we already looked up this method, we're done.
257   if (S.NSNumberLiteralMethods[*Kind])
258     return S.NSNumberLiteralMethods[*Kind];
259 
260   Selector Sel = S.NSAPIObj->getNSNumberLiteralSelector(*Kind,
261                                                         /*Instance=*/false);
262 
263   ASTContext &CX = S.Context;
264 
265   // Look up the NSNumber class, if we haven't done so already. It's cached
266   // in the Sema instance.
267   if (!S.NSNumberDecl) {
268     S.NSNumberDecl = LookupObjCInterfaceDeclForLiteral(S, Loc,
269                                                        Sema::LK_Numeric);
270     if (!S.NSNumberDecl) {
271       return nullptr;
272     }
273   }
274 
275   if (S.NSNumberPointer.isNull()) {
276     // generate the pointer to NSNumber type.
277     QualType NSNumberObject = CX.getObjCInterfaceType(S.NSNumberDecl);
278     S.NSNumberPointer = CX.getObjCObjectPointerType(NSNumberObject);
279   }
280 
281   // Look for the appropriate method within NSNumber.
282   ObjCMethodDecl *Method = S.NSNumberDecl->lookupClassMethod(Sel);
283   if (!Method && S.getLangOpts().DebuggerObjCLiteral) {
284     // create a stub definition this NSNumber factory method.
285     TypeSourceInfo *ReturnTInfo = nullptr;
286     Method =
287         ObjCMethodDecl::Create(CX, SourceLocation(), SourceLocation(), Sel,
288                                S.NSNumberPointer, ReturnTInfo, S.NSNumberDecl,
289                                /*isInstance=*/false, /*isVariadic=*/false,
290                                /*isPropertyAccessor=*/false,
291                                /*isImplicitlyDeclared=*/true,
292                                /*isDefined=*/false, ObjCMethodDecl::Required,
293                                /*HasRelatedResultType=*/false);
294     ParmVarDecl *value = ParmVarDecl::Create(S.Context, Method,
295                                              SourceLocation(), SourceLocation(),
296                                              &CX.Idents.get("value"),
297                                              NumberType, /*TInfo=*/nullptr,
298                                              SC_None, nullptr);
299     Method->setMethodParams(S.Context, value, None);
300   }
301 
302   if (!validateBoxingMethod(S, Loc, S.NSNumberDecl, Sel, Method))
303     return nullptr;
304 
305   // Note: if the parameter type is out-of-line, we'll catch it later in the
306   // implicit conversion.
307 
308   S.NSNumberLiteralMethods[*Kind] = Method;
309   return Method;
310 }
311 
312 /// BuildObjCNumericLiteral - builds an ObjCBoxedExpr AST node for the
313 /// numeric literal expression. Type of the expression will be "NSNumber *".
314 ExprResult Sema::BuildObjCNumericLiteral(SourceLocation AtLoc, Expr *Number) {
315   // Determine the type of the literal.
316   QualType NumberType = Number->getType();
317   if (CharacterLiteral *Char = dyn_cast<CharacterLiteral>(Number)) {
318     // In C, character literals have type 'int'. That's not the type we want
319     // to use to determine the Objective-c literal kind.
320     switch (Char->getKind()) {
321     case CharacterLiteral::Ascii:
322     case CharacterLiteral::UTF8:
323       NumberType = Context.CharTy;
324       break;
325 
326     case CharacterLiteral::Wide:
327       NumberType = Context.getWideCharType();
328       break;
329 
330     case CharacterLiteral::UTF16:
331       NumberType = Context.Char16Ty;
332       break;
333 
334     case CharacterLiteral::UTF32:
335       NumberType = Context.Char32Ty;
336       break;
337     }
338   }
339 
340   // Look for the appropriate method within NSNumber.
341   // Construct the literal.
342   SourceRange NR(Number->getSourceRange());
343   ObjCMethodDecl *Method = getNSNumberFactoryMethod(*this, AtLoc, NumberType,
344                                                     true, NR);
345   if (!Method)
346     return ExprError();
347 
348   // Convert the number to the type that the parameter expects.
349   ParmVarDecl *ParamDecl = Method->parameters()[0];
350   InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
351                                                                     ParamDecl);
352   ExprResult ConvertedNumber = PerformCopyInitialization(Entity,
353                                                          SourceLocation(),
354                                                          Number);
355   if (ConvertedNumber.isInvalid())
356     return ExprError();
357   Number = ConvertedNumber.get();
358 
359   // Use the effective source range of the literal, including the leading '@'.
360   return MaybeBindToTemporary(
361            new (Context) ObjCBoxedExpr(Number, NSNumberPointer, Method,
362                                        SourceRange(AtLoc, NR.getEnd())));
363 }
364 
365 ExprResult Sema::ActOnObjCBoolLiteral(SourceLocation AtLoc,
366                                       SourceLocation ValueLoc,
367                                       bool Value) {
368   ExprResult Inner;
369   if (getLangOpts().CPlusPlus) {
370     Inner = ActOnCXXBoolLiteral(ValueLoc, Value? tok::kw_true : tok::kw_false);
371   } else {
372     // C doesn't actually have a way to represent literal values of type
373     // _Bool. So, we'll use 0/1 and implicit cast to _Bool.
374     Inner = ActOnIntegerConstant(ValueLoc, Value? 1 : 0);
375     Inner = ImpCastExprToType(Inner.get(), Context.BoolTy,
376                               CK_IntegralToBoolean);
377   }
378 
379   return BuildObjCNumericLiteral(AtLoc, Inner.get());
380 }
381 
382 /// Check that the given expression is a valid element of an Objective-C
383 /// collection literal.
384 static ExprResult CheckObjCCollectionLiteralElement(Sema &S, Expr *Element,
385                                                     QualType T,
386                                                     bool ArrayLiteral = false) {
387   // If the expression is type-dependent, there's nothing for us to do.
388   if (Element->isTypeDependent())
389     return Element;
390 
391   ExprResult Result = S.CheckPlaceholderExpr(Element);
392   if (Result.isInvalid())
393     return ExprError();
394   Element = Result.get();
395 
396   // In C++, check for an implicit conversion to an Objective-C object pointer
397   // type.
398   if (S.getLangOpts().CPlusPlus && Element->getType()->isRecordType()) {
399     InitializedEntity Entity
400       = InitializedEntity::InitializeParameter(S.Context, T,
401                                                /*Consumed=*/false);
402     InitializationKind Kind = InitializationKind::CreateCopy(
403         Element->getBeginLoc(), SourceLocation());
404     InitializationSequence Seq(S, Entity, Kind, Element);
405     if (!Seq.Failed())
406       return Seq.Perform(S, Entity, Kind, Element);
407   }
408 
409   Expr *OrigElement = Element;
410 
411   // Perform lvalue-to-rvalue conversion.
412   Result = S.DefaultLvalueConversion(Element);
413   if (Result.isInvalid())
414     return ExprError();
415   Element = Result.get();
416 
417   // Make sure that we have an Objective-C pointer type or block.
418   if (!Element->getType()->isObjCObjectPointerType() &&
419       !Element->getType()->isBlockPointerType()) {
420     bool Recovered = false;
421 
422     // If this is potentially an Objective-C numeric literal, add the '@'.
423     if (isa<IntegerLiteral>(OrigElement) ||
424         isa<CharacterLiteral>(OrigElement) ||
425         isa<FloatingLiteral>(OrigElement) ||
426         isa<ObjCBoolLiteralExpr>(OrigElement) ||
427         isa<CXXBoolLiteralExpr>(OrigElement)) {
428       if (S.NSAPIObj->getNSNumberFactoryMethodKind(OrigElement->getType())) {
429         int Which = isa<CharacterLiteral>(OrigElement) ? 1
430                   : (isa<CXXBoolLiteralExpr>(OrigElement) ||
431                      isa<ObjCBoolLiteralExpr>(OrigElement)) ? 2
432                   : 3;
433 
434         S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
435             << Which << OrigElement->getSourceRange()
436             << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
437 
438         Result =
439             S.BuildObjCNumericLiteral(OrigElement->getBeginLoc(), OrigElement);
440         if (Result.isInvalid())
441           return ExprError();
442 
443         Element = Result.get();
444         Recovered = true;
445       }
446     }
447     // If this is potentially an Objective-C string literal, add the '@'.
448     else if (StringLiteral *String = dyn_cast<StringLiteral>(OrigElement)) {
449       if (String->isAscii()) {
450         S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
451             << 0 << OrigElement->getSourceRange()
452             << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
453 
454         Result = S.BuildObjCStringLiteral(OrigElement->getBeginLoc(), String);
455         if (Result.isInvalid())
456           return ExprError();
457 
458         Element = Result.get();
459         Recovered = true;
460       }
461     }
462 
463     if (!Recovered) {
464       S.Diag(Element->getBeginLoc(), diag::err_invalid_collection_element)
465           << Element->getType();
466       return ExprError();
467     }
468   }
469   if (ArrayLiteral)
470     if (ObjCStringLiteral *getString =
471           dyn_cast<ObjCStringLiteral>(OrigElement)) {
472       if (StringLiteral *SL = getString->getString()) {
473         unsigned numConcat = SL->getNumConcatenated();
474         if (numConcat > 1) {
475           // Only warn if the concatenated string doesn't come from a macro.
476           bool hasMacro = false;
477           for (unsigned i = 0; i < numConcat ; ++i)
478             if (SL->getStrTokenLoc(i).isMacroID()) {
479               hasMacro = true;
480               break;
481             }
482           if (!hasMacro)
483             S.Diag(Element->getBeginLoc(),
484                    diag::warn_concatenated_nsarray_literal)
485                 << Element->getType();
486         }
487       }
488     }
489 
490   // Make sure that the element has the type that the container factory
491   // function expects.
492   return S.PerformCopyInitialization(
493       InitializedEntity::InitializeParameter(S.Context, T,
494                                              /*Consumed=*/false),
495       Element->getBeginLoc(), Element);
496 }
497 
498 ExprResult Sema::BuildObjCBoxedExpr(SourceRange SR, Expr *ValueExpr) {
499   if (ValueExpr->isTypeDependent()) {
500     ObjCBoxedExpr *BoxedExpr =
501       new (Context) ObjCBoxedExpr(ValueExpr, Context.DependentTy, nullptr, SR);
502     return BoxedExpr;
503   }
504   ObjCMethodDecl *BoxingMethod = nullptr;
505   QualType BoxedType;
506   // Convert the expression to an RValue, so we can check for pointer types...
507   ExprResult RValue = DefaultFunctionArrayLvalueConversion(ValueExpr);
508   if (RValue.isInvalid()) {
509     return ExprError();
510   }
511   SourceLocation Loc = SR.getBegin();
512   ValueExpr = RValue.get();
513   QualType ValueType(ValueExpr->getType());
514   if (const PointerType *PT = ValueType->getAs<PointerType>()) {
515     QualType PointeeType = PT->getPointeeType();
516     if (Context.hasSameUnqualifiedType(PointeeType, Context.CharTy)) {
517 
518       if (!NSStringDecl) {
519         NSStringDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
520                                                          Sema::LK_String);
521         if (!NSStringDecl) {
522           return ExprError();
523         }
524         QualType NSStringObject = Context.getObjCInterfaceType(NSStringDecl);
525         NSStringPointer = Context.getObjCObjectPointerType(NSStringObject);
526       }
527 
528       // The boxed expression can be emitted as a compile time constant if it is
529       // a string literal whose character encoding is compatible with UTF-8.
530       if (auto *CE = dyn_cast<ImplicitCastExpr>(ValueExpr))
531         if (CE->getCastKind() == CK_ArrayToPointerDecay)
532           if (auto *SL =
533                   dyn_cast<StringLiteral>(CE->getSubExpr()->IgnoreParens())) {
534             assert((SL->isAscii() || SL->isUTF8()) &&
535                    "unexpected character encoding");
536             StringRef Str = SL->getString();
537             const llvm::UTF8 *StrBegin = Str.bytes_begin();
538             const llvm::UTF8 *StrEnd = Str.bytes_end();
539             // Check that this is a valid UTF-8 string.
540             if (llvm::isLegalUTF8String(&StrBegin, StrEnd)) {
541               BoxedType = Context.getAttributedType(
542                   AttributedType::getNullabilityAttrKind(
543                       NullabilityKind::NonNull),
544                   NSStringPointer, NSStringPointer);
545               return new (Context) ObjCBoxedExpr(CE, BoxedType, nullptr, SR);
546             }
547 
548             Diag(SL->getBeginLoc(), diag::warn_objc_boxing_invalid_utf8_string)
549                 << NSStringPointer << SL->getSourceRange();
550           }
551 
552       if (!StringWithUTF8StringMethod) {
553         IdentifierInfo *II = &Context.Idents.get("stringWithUTF8String");
554         Selector stringWithUTF8String = Context.Selectors.getUnarySelector(II);
555 
556         // Look for the appropriate method within NSString.
557         BoxingMethod = NSStringDecl->lookupClassMethod(stringWithUTF8String);
558         if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
559           // Debugger needs to work even if NSString hasn't been defined.
560           TypeSourceInfo *ReturnTInfo = nullptr;
561           ObjCMethodDecl *M = ObjCMethodDecl::Create(
562               Context, SourceLocation(), SourceLocation(), stringWithUTF8String,
563               NSStringPointer, ReturnTInfo, NSStringDecl,
564               /*isInstance=*/false, /*isVariadic=*/false,
565               /*isPropertyAccessor=*/false,
566               /*isImplicitlyDeclared=*/true,
567               /*isDefined=*/false, ObjCMethodDecl::Required,
568               /*HasRelatedResultType=*/false);
569           QualType ConstCharType = Context.CharTy.withConst();
570           ParmVarDecl *value =
571             ParmVarDecl::Create(Context, M,
572                                 SourceLocation(), SourceLocation(),
573                                 &Context.Idents.get("value"),
574                                 Context.getPointerType(ConstCharType),
575                                 /*TInfo=*/nullptr,
576                                 SC_None, nullptr);
577           M->setMethodParams(Context, value, None);
578           BoxingMethod = M;
579         }
580 
581         if (!validateBoxingMethod(*this, Loc, NSStringDecl,
582                                   stringWithUTF8String, BoxingMethod))
583            return ExprError();
584 
585         StringWithUTF8StringMethod = BoxingMethod;
586       }
587 
588       BoxingMethod = StringWithUTF8StringMethod;
589       BoxedType = NSStringPointer;
590       // Transfer the nullability from method's return type.
591       Optional<NullabilityKind> Nullability =
592           BoxingMethod->getReturnType()->getNullability(Context);
593       if (Nullability)
594         BoxedType = Context.getAttributedType(
595             AttributedType::getNullabilityAttrKind(*Nullability), BoxedType,
596             BoxedType);
597     }
598   } else if (ValueType->isBuiltinType()) {
599     // The other types we support are numeric, char and BOOL/bool. We could also
600     // provide limited support for structure types, such as NSRange, NSRect, and
601     // NSSize. See NSValue (NSValueGeometryExtensions) in <Foundation/NSGeometry.h>
602     // for more details.
603 
604     // Check for a top-level character literal.
605     if (const CharacterLiteral *Char =
606         dyn_cast<CharacterLiteral>(ValueExpr->IgnoreParens())) {
607       // In C, character literals have type 'int'. That's not the type we want
608       // to use to determine the Objective-c literal kind.
609       switch (Char->getKind()) {
610       case CharacterLiteral::Ascii:
611       case CharacterLiteral::UTF8:
612         ValueType = Context.CharTy;
613         break;
614 
615       case CharacterLiteral::Wide:
616         ValueType = Context.getWideCharType();
617         break;
618 
619       case CharacterLiteral::UTF16:
620         ValueType = Context.Char16Ty;
621         break;
622 
623       case CharacterLiteral::UTF32:
624         ValueType = Context.Char32Ty;
625         break;
626       }
627     }
628     // FIXME:  Do I need to do anything special with BoolTy expressions?
629 
630     // Look for the appropriate method within NSNumber.
631     BoxingMethod = getNSNumberFactoryMethod(*this, Loc, ValueType);
632     BoxedType = NSNumberPointer;
633   } else if (const EnumType *ET = ValueType->getAs<EnumType>()) {
634     if (!ET->getDecl()->isComplete()) {
635       Diag(Loc, diag::err_objc_incomplete_boxed_expression_type)
636         << ValueType << ValueExpr->getSourceRange();
637       return ExprError();
638     }
639 
640     BoxingMethod = getNSNumberFactoryMethod(*this, Loc,
641                                             ET->getDecl()->getIntegerType());
642     BoxedType = NSNumberPointer;
643   } else if (ValueType->isObjCBoxableRecordType()) {
644     // Support for structure types, that marked as objc_boxable
645     // struct __attribute__((objc_boxable)) s { ... };
646 
647     // Look up the NSValue class, if we haven't done so already. It's cached
648     // in the Sema instance.
649     if (!NSValueDecl) {
650       NSValueDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
651                                                       Sema::LK_Boxed);
652       if (!NSValueDecl) {
653         return ExprError();
654       }
655 
656       // generate the pointer to NSValue type.
657       QualType NSValueObject = Context.getObjCInterfaceType(NSValueDecl);
658       NSValuePointer = Context.getObjCObjectPointerType(NSValueObject);
659     }
660 
661     if (!ValueWithBytesObjCTypeMethod) {
662       IdentifierInfo *II[] = {
663         &Context.Idents.get("valueWithBytes"),
664         &Context.Idents.get("objCType")
665       };
666       Selector ValueWithBytesObjCType = Context.Selectors.getSelector(2, II);
667 
668       // Look for the appropriate method within NSValue.
669       BoxingMethod = NSValueDecl->lookupClassMethod(ValueWithBytesObjCType);
670       if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
671         // Debugger needs to work even if NSValue hasn't been defined.
672         TypeSourceInfo *ReturnTInfo = nullptr;
673         ObjCMethodDecl *M = ObjCMethodDecl::Create(
674                                                Context,
675                                                SourceLocation(),
676                                                SourceLocation(),
677                                                ValueWithBytesObjCType,
678                                                NSValuePointer,
679                                                ReturnTInfo,
680                                                NSValueDecl,
681                                                /*isInstance=*/false,
682                                                /*isVariadic=*/false,
683                                                /*isPropertyAccessor=*/false,
684                                                /*isImplicitlyDeclared=*/true,
685                                                /*isDefined=*/false,
686                                                ObjCMethodDecl::Required,
687                                                /*HasRelatedResultType=*/false);
688 
689         SmallVector<ParmVarDecl *, 2> Params;
690 
691         ParmVarDecl *bytes =
692         ParmVarDecl::Create(Context, M,
693                             SourceLocation(), SourceLocation(),
694                             &Context.Idents.get("bytes"),
695                             Context.VoidPtrTy.withConst(),
696                             /*TInfo=*/nullptr,
697                             SC_None, nullptr);
698         Params.push_back(bytes);
699 
700         QualType ConstCharType = Context.CharTy.withConst();
701         ParmVarDecl *type =
702         ParmVarDecl::Create(Context, M,
703                             SourceLocation(), SourceLocation(),
704                             &Context.Idents.get("type"),
705                             Context.getPointerType(ConstCharType),
706                             /*TInfo=*/nullptr,
707                             SC_None, nullptr);
708         Params.push_back(type);
709 
710         M->setMethodParams(Context, Params, None);
711         BoxingMethod = M;
712       }
713 
714       if (!validateBoxingMethod(*this, Loc, NSValueDecl,
715                                 ValueWithBytesObjCType, BoxingMethod))
716         return ExprError();
717 
718       ValueWithBytesObjCTypeMethod = BoxingMethod;
719     }
720 
721     if (!ValueType.isTriviallyCopyableType(Context)) {
722       Diag(Loc, diag::err_objc_non_trivially_copyable_boxed_expression_type)
723         << ValueType << ValueExpr->getSourceRange();
724       return ExprError();
725     }
726 
727     BoxingMethod = ValueWithBytesObjCTypeMethod;
728     BoxedType = NSValuePointer;
729   }
730 
731   if (!BoxingMethod) {
732     Diag(Loc, diag::err_objc_illegal_boxed_expression_type)
733       << ValueType << ValueExpr->getSourceRange();
734     return ExprError();
735   }
736 
737   DiagnoseUseOfDecl(BoxingMethod, Loc);
738 
739   ExprResult ConvertedValueExpr;
740   if (ValueType->isObjCBoxableRecordType()) {
741     InitializedEntity IE = InitializedEntity::InitializeTemporary(ValueType);
742     ConvertedValueExpr = PerformCopyInitialization(IE, ValueExpr->getExprLoc(),
743                                                    ValueExpr);
744   } else {
745     // Convert the expression to the type that the parameter requires.
746     ParmVarDecl *ParamDecl = BoxingMethod->parameters()[0];
747     InitializedEntity IE = InitializedEntity::InitializeParameter(Context,
748                                                                   ParamDecl);
749     ConvertedValueExpr = PerformCopyInitialization(IE, SourceLocation(),
750                                                    ValueExpr);
751   }
752 
753   if (ConvertedValueExpr.isInvalid())
754     return ExprError();
755   ValueExpr = ConvertedValueExpr.get();
756 
757   ObjCBoxedExpr *BoxedExpr =
758     new (Context) ObjCBoxedExpr(ValueExpr, BoxedType,
759                                       BoxingMethod, SR);
760   return MaybeBindToTemporary(BoxedExpr);
761 }
762 
763 /// Build an ObjC subscript pseudo-object expression, given that
764 /// that's supported by the runtime.
765 ExprResult Sema::BuildObjCSubscriptExpression(SourceLocation RB, Expr *BaseExpr,
766                                         Expr *IndexExpr,
767                                         ObjCMethodDecl *getterMethod,
768                                         ObjCMethodDecl *setterMethod) {
769   assert(!LangOpts.isSubscriptPointerArithmetic());
770 
771   // We can't get dependent types here; our callers should have
772   // filtered them out.
773   assert((!BaseExpr->isTypeDependent() && !IndexExpr->isTypeDependent()) &&
774          "base or index cannot have dependent type here");
775 
776   // Filter out placeholders in the index.  In theory, overloads could
777   // be preserved here, although that might not actually work correctly.
778   ExprResult Result = CheckPlaceholderExpr(IndexExpr);
779   if (Result.isInvalid())
780     return ExprError();
781   IndexExpr = Result.get();
782 
783   // Perform lvalue-to-rvalue conversion on the base.
784   Result = DefaultLvalueConversion(BaseExpr);
785   if (Result.isInvalid())
786     return ExprError();
787   BaseExpr = Result.get();
788 
789   // Build the pseudo-object expression.
790   return new (Context) ObjCSubscriptRefExpr(
791       BaseExpr, IndexExpr, Context.PseudoObjectTy, VK_LValue, OK_ObjCSubscript,
792       getterMethod, setterMethod, RB);
793 }
794 
795 ExprResult Sema::BuildObjCArrayLiteral(SourceRange SR, MultiExprArg Elements) {
796   SourceLocation Loc = SR.getBegin();
797 
798   if (!NSArrayDecl) {
799     NSArrayDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
800                                                     Sema::LK_Array);
801     if (!NSArrayDecl) {
802       return ExprError();
803     }
804   }
805 
806   // Find the arrayWithObjects:count: method, if we haven't done so already.
807   QualType IdT = Context.getObjCIdType();
808   if (!ArrayWithObjectsMethod) {
809     Selector
810       Sel = NSAPIObj->getNSArraySelector(NSAPI::NSArr_arrayWithObjectsCount);
811     ObjCMethodDecl *Method = NSArrayDecl->lookupClassMethod(Sel);
812     if (!Method && getLangOpts().DebuggerObjCLiteral) {
813       TypeSourceInfo *ReturnTInfo = nullptr;
814       Method = ObjCMethodDecl::Create(
815           Context, SourceLocation(), SourceLocation(), Sel, IdT, ReturnTInfo,
816           Context.getTranslationUnitDecl(), false /*Instance*/,
817           false /*isVariadic*/,
818           /*isPropertyAccessor=*/false,
819           /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
820           ObjCMethodDecl::Required, false);
821       SmallVector<ParmVarDecl *, 2> Params;
822       ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
823                                                  SourceLocation(),
824                                                  SourceLocation(),
825                                                  &Context.Idents.get("objects"),
826                                                  Context.getPointerType(IdT),
827                                                  /*TInfo=*/nullptr,
828                                                  SC_None, nullptr);
829       Params.push_back(objects);
830       ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
831                                              SourceLocation(),
832                                              SourceLocation(),
833                                              &Context.Idents.get("cnt"),
834                                              Context.UnsignedLongTy,
835                                              /*TInfo=*/nullptr, SC_None,
836                                              nullptr);
837       Params.push_back(cnt);
838       Method->setMethodParams(Context, Params, None);
839     }
840 
841     if (!validateBoxingMethod(*this, Loc, NSArrayDecl, Sel, Method))
842       return ExprError();
843 
844     // Dig out the type that all elements should be converted to.
845     QualType T = Method->parameters()[0]->getType();
846     const PointerType *PtrT = T->getAs<PointerType>();
847     if (!PtrT ||
848         !Context.hasSameUnqualifiedType(PtrT->getPointeeType(), IdT)) {
849       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
850         << Sel;
851       Diag(Method->parameters()[0]->getLocation(),
852            diag::note_objc_literal_method_param)
853         << 0 << T
854         << Context.getPointerType(IdT.withConst());
855       return ExprError();
856     }
857 
858     // Check that the 'count' parameter is integral.
859     if (!Method->parameters()[1]->getType()->isIntegerType()) {
860       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
861         << Sel;
862       Diag(Method->parameters()[1]->getLocation(),
863            diag::note_objc_literal_method_param)
864         << 1
865         << Method->parameters()[1]->getType()
866         << "integral";
867       return ExprError();
868     }
869 
870     // We've found a good +arrayWithObjects:count: method. Save it!
871     ArrayWithObjectsMethod = Method;
872   }
873 
874   QualType ObjectsType = ArrayWithObjectsMethod->parameters()[0]->getType();
875   QualType RequiredType = ObjectsType->castAs<PointerType>()->getPointeeType();
876 
877   // Check that each of the elements provided is valid in a collection literal,
878   // performing conversions as necessary.
879   Expr **ElementsBuffer = Elements.data();
880   for (unsigned I = 0, N = Elements.size(); I != N; ++I) {
881     ExprResult Converted = CheckObjCCollectionLiteralElement(*this,
882                                                              ElementsBuffer[I],
883                                                              RequiredType, true);
884     if (Converted.isInvalid())
885       return ExprError();
886 
887     ElementsBuffer[I] = Converted.get();
888   }
889 
890   QualType Ty
891     = Context.getObjCObjectPointerType(
892                                     Context.getObjCInterfaceType(NSArrayDecl));
893 
894   return MaybeBindToTemporary(
895            ObjCArrayLiteral::Create(Context, Elements, Ty,
896                                     ArrayWithObjectsMethod, SR));
897 }
898 
899 ExprResult Sema::BuildObjCDictionaryLiteral(SourceRange SR,
900                               MutableArrayRef<ObjCDictionaryElement> Elements) {
901   SourceLocation Loc = SR.getBegin();
902 
903   if (!NSDictionaryDecl) {
904     NSDictionaryDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
905                                                          Sema::LK_Dictionary);
906     if (!NSDictionaryDecl) {
907       return ExprError();
908     }
909   }
910 
911   // Find the dictionaryWithObjects:forKeys:count: method, if we haven't done
912   // so already.
913   QualType IdT = Context.getObjCIdType();
914   if (!DictionaryWithObjectsMethod) {
915     Selector Sel = NSAPIObj->getNSDictionarySelector(
916                                NSAPI::NSDict_dictionaryWithObjectsForKeysCount);
917     ObjCMethodDecl *Method = NSDictionaryDecl->lookupClassMethod(Sel);
918     if (!Method && getLangOpts().DebuggerObjCLiteral) {
919       Method = ObjCMethodDecl::Create(Context,
920                            SourceLocation(), SourceLocation(), Sel,
921                            IdT,
922                            nullptr /*TypeSourceInfo */,
923                            Context.getTranslationUnitDecl(),
924                            false /*Instance*/, false/*isVariadic*/,
925                            /*isPropertyAccessor=*/false,
926                            /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
927                            ObjCMethodDecl::Required,
928                            false);
929       SmallVector<ParmVarDecl *, 3> Params;
930       ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
931                                                  SourceLocation(),
932                                                  SourceLocation(),
933                                                  &Context.Idents.get("objects"),
934                                                  Context.getPointerType(IdT),
935                                                  /*TInfo=*/nullptr, SC_None,
936                                                  nullptr);
937       Params.push_back(objects);
938       ParmVarDecl *keys = ParmVarDecl::Create(Context, Method,
939                                               SourceLocation(),
940                                               SourceLocation(),
941                                               &Context.Idents.get("keys"),
942                                               Context.getPointerType(IdT),
943                                               /*TInfo=*/nullptr, SC_None,
944                                               nullptr);
945       Params.push_back(keys);
946       ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
947                                              SourceLocation(),
948                                              SourceLocation(),
949                                              &Context.Idents.get("cnt"),
950                                              Context.UnsignedLongTy,
951                                              /*TInfo=*/nullptr, SC_None,
952                                              nullptr);
953       Params.push_back(cnt);
954       Method->setMethodParams(Context, Params, None);
955     }
956 
957     if (!validateBoxingMethod(*this, SR.getBegin(), NSDictionaryDecl, Sel,
958                               Method))
959        return ExprError();
960 
961     // Dig out the type that all values should be converted to.
962     QualType ValueT = Method->parameters()[0]->getType();
963     const PointerType *PtrValue = ValueT->getAs<PointerType>();
964     if (!PtrValue ||
965         !Context.hasSameUnqualifiedType(PtrValue->getPointeeType(), IdT)) {
966       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
967         << Sel;
968       Diag(Method->parameters()[0]->getLocation(),
969            diag::note_objc_literal_method_param)
970         << 0 << ValueT
971         << Context.getPointerType(IdT.withConst());
972       return ExprError();
973     }
974 
975     // Dig out the type that all keys should be converted to.
976     QualType KeyT = Method->parameters()[1]->getType();
977     const PointerType *PtrKey = KeyT->getAs<PointerType>();
978     if (!PtrKey ||
979         !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
980                                         IdT)) {
981       bool err = true;
982       if (PtrKey) {
983         if (QIDNSCopying.isNull()) {
984           // key argument of selector is id<NSCopying>?
985           if (ObjCProtocolDecl *NSCopyingPDecl =
986               LookupProtocol(&Context.Idents.get("NSCopying"), SR.getBegin())) {
987             ObjCProtocolDecl *PQ[] = {NSCopyingPDecl};
988             QIDNSCopying =
989               Context.getObjCObjectType(Context.ObjCBuiltinIdTy, { },
990                                         llvm::makeArrayRef(
991                                           (ObjCProtocolDecl**) PQ,
992                                           1),
993                                         false);
994             QIDNSCopying = Context.getObjCObjectPointerType(QIDNSCopying);
995           }
996         }
997         if (!QIDNSCopying.isNull())
998           err = !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
999                                                 QIDNSCopying);
1000       }
1001 
1002       if (err) {
1003         Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
1004           << Sel;
1005         Diag(Method->parameters()[1]->getLocation(),
1006              diag::note_objc_literal_method_param)
1007           << 1 << KeyT
1008           << Context.getPointerType(IdT.withConst());
1009         return ExprError();
1010       }
1011     }
1012 
1013     // Check that the 'count' parameter is integral.
1014     QualType CountType = Method->parameters()[2]->getType();
1015     if (!CountType->isIntegerType()) {
1016       Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
1017         << Sel;
1018       Diag(Method->parameters()[2]->getLocation(),
1019            diag::note_objc_literal_method_param)
1020         << 2 << CountType
1021         << "integral";
1022       return ExprError();
1023     }
1024 
1025     // We've found a good +dictionaryWithObjects:keys:count: method; save it!
1026     DictionaryWithObjectsMethod = Method;
1027   }
1028 
1029   QualType ValuesT = DictionaryWithObjectsMethod->parameters()[0]->getType();
1030   QualType ValueT = ValuesT->castAs<PointerType>()->getPointeeType();
1031   QualType KeysT = DictionaryWithObjectsMethod->parameters()[1]->getType();
1032   QualType KeyT = KeysT->castAs<PointerType>()->getPointeeType();
1033 
1034   // Check that each of the keys and values provided is valid in a collection
1035   // literal, performing conversions as necessary.
1036   bool HasPackExpansions = false;
1037   for (ObjCDictionaryElement &Element : Elements) {
1038     // Check the key.
1039     ExprResult Key = CheckObjCCollectionLiteralElement(*this, Element.Key,
1040                                                        KeyT);
1041     if (Key.isInvalid())
1042       return ExprError();
1043 
1044     // Check the value.
1045     ExprResult Value
1046       = CheckObjCCollectionLiteralElement(*this, Element.Value, ValueT);
1047     if (Value.isInvalid())
1048       return ExprError();
1049 
1050     Element.Key = Key.get();
1051     Element.Value = Value.get();
1052 
1053     if (Element.EllipsisLoc.isInvalid())
1054       continue;
1055 
1056     if (!Element.Key->containsUnexpandedParameterPack() &&
1057         !Element.Value->containsUnexpandedParameterPack()) {
1058       Diag(Element.EllipsisLoc,
1059            diag::err_pack_expansion_without_parameter_packs)
1060           << SourceRange(Element.Key->getBeginLoc(),
1061                          Element.Value->getEndLoc());
1062       return ExprError();
1063     }
1064 
1065     HasPackExpansions = true;
1066   }
1067 
1068   QualType Ty
1069     = Context.getObjCObjectPointerType(
1070                                 Context.getObjCInterfaceType(NSDictionaryDecl));
1071   return MaybeBindToTemporary(ObjCDictionaryLiteral::Create(
1072       Context, Elements, HasPackExpansions, Ty,
1073       DictionaryWithObjectsMethod, SR));
1074 }
1075 
1076 ExprResult Sema::BuildObjCEncodeExpression(SourceLocation AtLoc,
1077                                       TypeSourceInfo *EncodedTypeInfo,
1078                                       SourceLocation RParenLoc) {
1079   QualType EncodedType = EncodedTypeInfo->getType();
1080   QualType StrTy;
1081   if (EncodedType->isDependentType())
1082     StrTy = Context.DependentTy;
1083   else {
1084     if (!EncodedType->getAsArrayTypeUnsafe() && //// Incomplete array is handled.
1085         !EncodedType->isVoidType()) // void is handled too.
1086       if (RequireCompleteType(AtLoc, EncodedType,
1087                               diag::err_incomplete_type_objc_at_encode,
1088                               EncodedTypeInfo->getTypeLoc()))
1089         return ExprError();
1090 
1091     std::string Str;
1092     QualType NotEncodedT;
1093     Context.getObjCEncodingForType(EncodedType, Str, nullptr, &NotEncodedT);
1094     if (!NotEncodedT.isNull())
1095       Diag(AtLoc, diag::warn_incomplete_encoded_type)
1096         << EncodedType << NotEncodedT;
1097 
1098     // The type of @encode is the same as the type of the corresponding string,
1099     // which is an array type.
1100     StrTy = Context.CharTy;
1101     // A C++ string literal has a const-qualified element type (C++ 2.13.4p1).
1102     if (getLangOpts().CPlusPlus || getLangOpts().ConstStrings)
1103       StrTy.addConst();
1104     StrTy = Context.getConstantArrayType(StrTy, llvm::APInt(32, Str.size()+1),
1105                                          ArrayType::Normal, 0);
1106   }
1107 
1108   return new (Context) ObjCEncodeExpr(StrTy, EncodedTypeInfo, AtLoc, RParenLoc);
1109 }
1110 
1111 ExprResult Sema::ParseObjCEncodeExpression(SourceLocation AtLoc,
1112                                            SourceLocation EncodeLoc,
1113                                            SourceLocation LParenLoc,
1114                                            ParsedType ty,
1115                                            SourceLocation RParenLoc) {
1116   // FIXME: Preserve type source info ?
1117   TypeSourceInfo *TInfo;
1118   QualType EncodedType = GetTypeFromParser(ty, &TInfo);
1119   if (!TInfo)
1120     TInfo = Context.getTrivialTypeSourceInfo(EncodedType,
1121                                              getLocForEndOfToken(LParenLoc));
1122 
1123   return BuildObjCEncodeExpression(AtLoc, TInfo, RParenLoc);
1124 }
1125 
1126 static bool HelperToDiagnoseMismatchedMethodsInGlobalPool(Sema &S,
1127                                                SourceLocation AtLoc,
1128                                                SourceLocation LParenLoc,
1129                                                SourceLocation RParenLoc,
1130                                                ObjCMethodDecl *Method,
1131                                                ObjCMethodList &MethList) {
1132   ObjCMethodList *M = &MethList;
1133   bool Warned = false;
1134   for (M = M->getNext(); M; M=M->getNext()) {
1135     ObjCMethodDecl *MatchingMethodDecl = M->getMethod();
1136     if (MatchingMethodDecl == Method ||
1137         isa<ObjCImplDecl>(MatchingMethodDecl->getDeclContext()) ||
1138         MatchingMethodDecl->getSelector() != Method->getSelector())
1139       continue;
1140     if (!S.MatchTwoMethodDeclarations(Method,
1141                                       MatchingMethodDecl, Sema::MMS_loose)) {
1142       if (!Warned) {
1143         Warned = true;
1144         S.Diag(AtLoc, diag::warn_multiple_selectors)
1145           << Method->getSelector() << FixItHint::CreateInsertion(LParenLoc, "(")
1146           << FixItHint::CreateInsertion(RParenLoc, ")");
1147         S.Diag(Method->getLocation(), diag::note_method_declared_at)
1148           << Method->getDeclName();
1149       }
1150       S.Diag(MatchingMethodDecl->getLocation(), diag::note_method_declared_at)
1151         << MatchingMethodDecl->getDeclName();
1152     }
1153   }
1154   return Warned;
1155 }
1156 
1157 static void DiagnoseMismatchedSelectors(Sema &S, SourceLocation AtLoc,
1158                                         ObjCMethodDecl *Method,
1159                                         SourceLocation LParenLoc,
1160                                         SourceLocation RParenLoc,
1161                                         bool WarnMultipleSelectors) {
1162   if (!WarnMultipleSelectors ||
1163       S.Diags.isIgnored(diag::warn_multiple_selectors, SourceLocation()))
1164     return;
1165   bool Warned = false;
1166   for (Sema::GlobalMethodPool::iterator b = S.MethodPool.begin(),
1167        e = S.MethodPool.end(); b != e; b++) {
1168     // first, instance methods
1169     ObjCMethodList &InstMethList = b->second.first;
1170     if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
1171                                                       Method, InstMethList))
1172       Warned = true;
1173 
1174     // second, class methods
1175     ObjCMethodList &ClsMethList = b->second.second;
1176     if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
1177                                                       Method, ClsMethList) || Warned)
1178       return;
1179   }
1180 }
1181 
1182 ExprResult Sema::ParseObjCSelectorExpression(Selector Sel,
1183                                              SourceLocation AtLoc,
1184                                              SourceLocation SelLoc,
1185                                              SourceLocation LParenLoc,
1186                                              SourceLocation RParenLoc,
1187                                              bool WarnMultipleSelectors) {
1188   ObjCMethodDecl *Method = LookupInstanceMethodInGlobalPool(Sel,
1189                              SourceRange(LParenLoc, RParenLoc));
1190   if (!Method)
1191     Method = LookupFactoryMethodInGlobalPool(Sel,
1192                                           SourceRange(LParenLoc, RParenLoc));
1193   if (!Method) {
1194     if (const ObjCMethodDecl *OM = SelectorsForTypoCorrection(Sel)) {
1195       Selector MatchedSel = OM->getSelector();
1196       SourceRange SelectorRange(LParenLoc.getLocWithOffset(1),
1197                                 RParenLoc.getLocWithOffset(-1));
1198       Diag(SelLoc, diag::warn_undeclared_selector_with_typo)
1199         << Sel << MatchedSel
1200         << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
1201 
1202     } else
1203         Diag(SelLoc, diag::warn_undeclared_selector) << Sel;
1204   } else
1205     DiagnoseMismatchedSelectors(*this, AtLoc, Method, LParenLoc, RParenLoc,
1206                                 WarnMultipleSelectors);
1207 
1208   if (Method &&
1209       Method->getImplementationControl() != ObjCMethodDecl::Optional &&
1210       !getSourceManager().isInSystemHeader(Method->getLocation()))
1211     ReferencedSelectors.insert(std::make_pair(Sel, AtLoc));
1212 
1213   // In ARC, forbid the user from using @selector for
1214   // retain/release/autorelease/dealloc/retainCount.
1215   if (getLangOpts().ObjCAutoRefCount) {
1216     switch (Sel.getMethodFamily()) {
1217     case OMF_retain:
1218     case OMF_release:
1219     case OMF_autorelease:
1220     case OMF_retainCount:
1221     case OMF_dealloc:
1222       Diag(AtLoc, diag::err_arc_illegal_selector) <<
1223         Sel << SourceRange(LParenLoc, RParenLoc);
1224       break;
1225 
1226     case OMF_None:
1227     case OMF_alloc:
1228     case OMF_copy:
1229     case OMF_finalize:
1230     case OMF_init:
1231     case OMF_mutableCopy:
1232     case OMF_new:
1233     case OMF_self:
1234     case OMF_initialize:
1235     case OMF_performSelector:
1236       break;
1237     }
1238   }
1239   QualType Ty = Context.getObjCSelType();
1240   return new (Context) ObjCSelectorExpr(Ty, Sel, AtLoc, RParenLoc);
1241 }
1242 
1243 ExprResult Sema::ParseObjCProtocolExpression(IdentifierInfo *ProtocolId,
1244                                              SourceLocation AtLoc,
1245                                              SourceLocation ProtoLoc,
1246                                              SourceLocation LParenLoc,
1247                                              SourceLocation ProtoIdLoc,
1248                                              SourceLocation RParenLoc) {
1249   ObjCProtocolDecl* PDecl = LookupProtocol(ProtocolId, ProtoIdLoc);
1250   if (!PDecl) {
1251     Diag(ProtoLoc, diag::err_undeclared_protocol) << ProtocolId;
1252     return true;
1253   }
1254   if (!PDecl->hasDefinition()) {
1255     Diag(ProtoLoc, diag::err_atprotocol_protocol) << PDecl;
1256     Diag(PDecl->getLocation(), diag::note_entity_declared_at) << PDecl;
1257   } else {
1258     PDecl = PDecl->getDefinition();
1259   }
1260 
1261   QualType Ty = Context.getObjCProtoType();
1262   if (Ty.isNull())
1263     return true;
1264   Ty = Context.getObjCObjectPointerType(Ty);
1265   return new (Context) ObjCProtocolExpr(Ty, PDecl, AtLoc, ProtoIdLoc, RParenLoc);
1266 }
1267 
1268 /// Try to capture an implicit reference to 'self'.
1269 ObjCMethodDecl *Sema::tryCaptureObjCSelf(SourceLocation Loc) {
1270   DeclContext *DC = getFunctionLevelDeclContext();
1271 
1272   // If we're not in an ObjC method, error out.  Note that, unlike the
1273   // C++ case, we don't require an instance method --- class methods
1274   // still have a 'self', and we really do still need to capture it!
1275   ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(DC);
1276   if (!method)
1277     return nullptr;
1278 
1279   tryCaptureVariable(method->getSelfDecl(), Loc);
1280 
1281   return method;
1282 }
1283 
1284 static QualType stripObjCInstanceType(ASTContext &Context, QualType T) {
1285   QualType origType = T;
1286   if (auto nullability = AttributedType::stripOuterNullability(T)) {
1287     if (T == Context.getObjCInstanceType()) {
1288       return Context.getAttributedType(
1289                AttributedType::getNullabilityAttrKind(*nullability),
1290                Context.getObjCIdType(),
1291                Context.getObjCIdType());
1292     }
1293 
1294     return origType;
1295   }
1296 
1297   if (T == Context.getObjCInstanceType())
1298     return Context.getObjCIdType();
1299 
1300   return origType;
1301 }
1302 
1303 /// Determine the result type of a message send based on the receiver type,
1304 /// method, and the kind of message send.
1305 ///
1306 /// This is the "base" result type, which will still need to be adjusted
1307 /// to account for nullability.
1308 static QualType getBaseMessageSendResultType(Sema &S,
1309                                              QualType ReceiverType,
1310                                              ObjCMethodDecl *Method,
1311                                              bool isClassMessage,
1312                                              bool isSuperMessage) {
1313   assert(Method && "Must have a method");
1314   if (!Method->hasRelatedResultType())
1315     return Method->getSendResultType(ReceiverType);
1316 
1317   ASTContext &Context = S.Context;
1318 
1319   // Local function that transfers the nullability of the method's
1320   // result type to the returned result.
1321   auto transferNullability = [&](QualType type) -> QualType {
1322     // If the method's result type has nullability, extract it.
1323     if (auto nullability = Method->getSendResultType(ReceiverType)
1324                              ->getNullability(Context)){
1325       // Strip off any outer nullability sugar from the provided type.
1326       (void)AttributedType::stripOuterNullability(type);
1327 
1328       // Form a new attributed type using the method result type's nullability.
1329       return Context.getAttributedType(
1330                AttributedType::getNullabilityAttrKind(*nullability),
1331                type,
1332                type);
1333     }
1334 
1335     return type;
1336   };
1337 
1338   // If a method has a related return type:
1339   //   - if the method found is an instance method, but the message send
1340   //     was a class message send, T is the declared return type of the method
1341   //     found
1342   if (Method->isInstanceMethod() && isClassMessage)
1343     return stripObjCInstanceType(Context,
1344                                  Method->getSendResultType(ReceiverType));
1345 
1346   //   - if the receiver is super, T is a pointer to the class of the
1347   //     enclosing method definition
1348   if (isSuperMessage) {
1349     if (ObjCMethodDecl *CurMethod = S.getCurMethodDecl())
1350       if (ObjCInterfaceDecl *Class = CurMethod->getClassInterface()) {
1351         return transferNullability(
1352                  Context.getObjCObjectPointerType(
1353                    Context.getObjCInterfaceType(Class)));
1354       }
1355   }
1356 
1357   //   - if the receiver is the name of a class U, T is a pointer to U
1358   if (ReceiverType->getAsObjCInterfaceType())
1359     return transferNullability(Context.getObjCObjectPointerType(ReceiverType));
1360   //   - if the receiver is of type Class or qualified Class type,
1361   //     T is the declared return type of the method.
1362   if (ReceiverType->isObjCClassType() ||
1363       ReceiverType->isObjCQualifiedClassType())
1364     return stripObjCInstanceType(Context,
1365                                  Method->getSendResultType(ReceiverType));
1366 
1367   //   - if the receiver is id, qualified id, Class, or qualified Class, T
1368   //     is the receiver type, otherwise
1369   //   - T is the type of the receiver expression.
1370   return transferNullability(ReceiverType);
1371 }
1372 
1373 QualType Sema::getMessageSendResultType(const Expr *Receiver,
1374                                         QualType ReceiverType,
1375                                         ObjCMethodDecl *Method,
1376                                         bool isClassMessage,
1377                                         bool isSuperMessage) {
1378   // Produce the result type.
1379   QualType resultType = getBaseMessageSendResultType(*this, ReceiverType,
1380                                                      Method,
1381                                                      isClassMessage,
1382                                                      isSuperMessage);
1383 
1384   // If this is a class message, ignore the nullability of the receiver.
1385   if (isClassMessage) {
1386     // In a class method, class messages to 'self' that return instancetype can
1387     // be typed as the current class.  We can safely do this in ARC because self
1388     // can't be reassigned, and we do it unsafely outside of ARC because in
1389     // practice people never reassign self in class methods and there's some
1390     // virtue in not being aggressively pedantic.
1391     if (Receiver && Receiver->isObjCSelfExpr()) {
1392       assert(ReceiverType->isObjCClassType() && "expected a Class self");
1393       QualType T = Method->getSendResultType(ReceiverType);
1394       AttributedType::stripOuterNullability(T);
1395       if (T == Context.getObjCInstanceType()) {
1396         const ObjCMethodDecl *MD = cast<ObjCMethodDecl>(
1397             cast<ImplicitParamDecl>(
1398                 cast<DeclRefExpr>(Receiver->IgnoreParenImpCasts())->getDecl())
1399                 ->getDeclContext());
1400         assert(MD->isClassMethod() && "expected a class method");
1401         QualType NewResultType = Context.getObjCObjectPointerType(
1402             Context.getObjCInterfaceType(MD->getClassInterface()));
1403         if (auto Nullability = resultType->getNullability(Context))
1404           NewResultType = Context.getAttributedType(
1405               AttributedType::getNullabilityAttrKind(*Nullability),
1406               NewResultType, NewResultType);
1407         return NewResultType;
1408       }
1409     }
1410     return resultType;
1411   }
1412 
1413   // There is nothing left to do if the result type cannot have a nullability
1414   // specifier.
1415   if (!resultType->canHaveNullability())
1416     return resultType;
1417 
1418   // Map the nullability of the result into a table index.
1419   unsigned receiverNullabilityIdx = 0;
1420   if (auto nullability = ReceiverType->getNullability(Context))
1421     receiverNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
1422 
1423   unsigned resultNullabilityIdx = 0;
1424   if (auto nullability = resultType->getNullability(Context))
1425     resultNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
1426 
1427   // The table of nullability mappings, indexed by the receiver's nullability
1428   // and then the result type's nullability.
1429   static const uint8_t None = 0;
1430   static const uint8_t NonNull = 1;
1431   static const uint8_t Nullable = 2;
1432   static const uint8_t Unspecified = 3;
1433   static const uint8_t nullabilityMap[4][4] = {
1434     //                  None        NonNull       Nullable    Unspecified
1435     /* None */        { None,       None,         Nullable,   None },
1436     /* NonNull */     { None,       NonNull,      Nullable,   Unspecified },
1437     /* Nullable */    { Nullable,   Nullable,     Nullable,   Nullable },
1438     /* Unspecified */ { None,       Unspecified,  Nullable,   Unspecified }
1439   };
1440 
1441   unsigned newResultNullabilityIdx
1442     = nullabilityMap[receiverNullabilityIdx][resultNullabilityIdx];
1443   if (newResultNullabilityIdx == resultNullabilityIdx)
1444     return resultType;
1445 
1446   // Strip off the existing nullability. This removes as little type sugar as
1447   // possible.
1448   do {
1449     if (auto attributed = dyn_cast<AttributedType>(resultType.getTypePtr())) {
1450       resultType = attributed->getModifiedType();
1451     } else {
1452       resultType = resultType.getDesugaredType(Context);
1453     }
1454   } while (resultType->getNullability(Context));
1455 
1456   // Add nullability back if needed.
1457   if (newResultNullabilityIdx > 0) {
1458     auto newNullability
1459       = static_cast<NullabilityKind>(newResultNullabilityIdx-1);
1460     return Context.getAttributedType(
1461              AttributedType::getNullabilityAttrKind(newNullability),
1462              resultType, resultType);
1463   }
1464 
1465   return resultType;
1466 }
1467 
1468 /// Look for an ObjC method whose result type exactly matches the given type.
1469 static const ObjCMethodDecl *
1470 findExplicitInstancetypeDeclarer(const ObjCMethodDecl *MD,
1471                                  QualType instancetype) {
1472   if (MD->getReturnType() == instancetype)
1473     return MD;
1474 
1475   // For these purposes, a method in an @implementation overrides a
1476   // declaration in the @interface.
1477   if (const ObjCImplDecl *impl =
1478         dyn_cast<ObjCImplDecl>(MD->getDeclContext())) {
1479     const ObjCContainerDecl *iface;
1480     if (const ObjCCategoryImplDecl *catImpl =
1481           dyn_cast<ObjCCategoryImplDecl>(impl)) {
1482       iface = catImpl->getCategoryDecl();
1483     } else {
1484       iface = impl->getClassInterface();
1485     }
1486 
1487     const ObjCMethodDecl *ifaceMD =
1488       iface->getMethod(MD->getSelector(), MD->isInstanceMethod());
1489     if (ifaceMD) return findExplicitInstancetypeDeclarer(ifaceMD, instancetype);
1490   }
1491 
1492   SmallVector<const ObjCMethodDecl *, 4> overrides;
1493   MD->getOverriddenMethods(overrides);
1494   for (unsigned i = 0, e = overrides.size(); i != e; ++i) {
1495     if (const ObjCMethodDecl *result =
1496           findExplicitInstancetypeDeclarer(overrides[i], instancetype))
1497       return result;
1498   }
1499 
1500   return nullptr;
1501 }
1502 
1503 void Sema::EmitRelatedResultTypeNoteForReturn(QualType destType) {
1504   // Only complain if we're in an ObjC method and the required return
1505   // type doesn't match the method's declared return type.
1506   ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(CurContext);
1507   if (!MD || !MD->hasRelatedResultType() ||
1508       Context.hasSameUnqualifiedType(destType, MD->getReturnType()))
1509     return;
1510 
1511   // Look for a method overridden by this method which explicitly uses
1512   // 'instancetype'.
1513   if (const ObjCMethodDecl *overridden =
1514         findExplicitInstancetypeDeclarer(MD, Context.getObjCInstanceType())) {
1515     SourceRange range = overridden->getReturnTypeSourceRange();
1516     SourceLocation loc = range.getBegin();
1517     if (loc.isInvalid())
1518       loc = overridden->getLocation();
1519     Diag(loc, diag::note_related_result_type_explicit)
1520       << /*current method*/ 1 << range;
1521     return;
1522   }
1523 
1524   // Otherwise, if we have an interesting method family, note that.
1525   // This should always trigger if the above didn't.
1526   if (ObjCMethodFamily family = MD->getMethodFamily())
1527     Diag(MD->getLocation(), diag::note_related_result_type_family)
1528       << /*current method*/ 1
1529       << family;
1530 }
1531 
1532 void Sema::EmitRelatedResultTypeNote(const Expr *E) {
1533   E = E->IgnoreParenImpCasts();
1534   const ObjCMessageExpr *MsgSend = dyn_cast<ObjCMessageExpr>(E);
1535   if (!MsgSend)
1536     return;
1537 
1538   const ObjCMethodDecl *Method = MsgSend->getMethodDecl();
1539   if (!Method)
1540     return;
1541 
1542   if (!Method->hasRelatedResultType())
1543     return;
1544 
1545   if (Context.hasSameUnqualifiedType(
1546           Method->getReturnType().getNonReferenceType(), MsgSend->getType()))
1547     return;
1548 
1549   if (!Context.hasSameUnqualifiedType(Method->getReturnType(),
1550                                       Context.getObjCInstanceType()))
1551     return;
1552 
1553   Diag(Method->getLocation(), diag::note_related_result_type_inferred)
1554     << Method->isInstanceMethod() << Method->getSelector()
1555     << MsgSend->getType();
1556 }
1557 
1558 bool Sema::CheckMessageArgumentTypes(
1559     const Expr *Receiver, QualType ReceiverType, MultiExprArg Args,
1560     Selector Sel, ArrayRef<SourceLocation> SelectorLocs, ObjCMethodDecl *Method,
1561     bool isClassMessage, bool isSuperMessage, SourceLocation lbrac,
1562     SourceLocation rbrac, SourceRange RecRange, QualType &ReturnType,
1563     ExprValueKind &VK) {
1564   SourceLocation SelLoc;
1565   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
1566     SelLoc = SelectorLocs.front();
1567   else
1568     SelLoc = lbrac;
1569 
1570   if (!Method) {
1571     // Apply default argument promotion as for (C99 6.5.2.2p6).
1572     for (unsigned i = 0, e = Args.size(); i != e; i++) {
1573       if (Args[i]->isTypeDependent())
1574         continue;
1575 
1576       ExprResult result;
1577       if (getLangOpts().DebuggerSupport) {
1578         QualType paramTy; // ignored
1579         result = checkUnknownAnyArg(SelLoc, Args[i], paramTy);
1580       } else {
1581         result = DefaultArgumentPromotion(Args[i]);
1582       }
1583       if (result.isInvalid())
1584         return true;
1585       Args[i] = result.get();
1586     }
1587 
1588     unsigned DiagID;
1589     if (getLangOpts().ObjCAutoRefCount)
1590       DiagID = diag::err_arc_method_not_found;
1591     else
1592       DiagID = isClassMessage ? diag::warn_class_method_not_found
1593                               : diag::warn_inst_method_not_found;
1594     if (!getLangOpts().DebuggerSupport) {
1595       const ObjCMethodDecl *OMD = SelectorsForTypoCorrection(Sel, ReceiverType);
1596       if (OMD && !OMD->isInvalidDecl()) {
1597         if (getLangOpts().ObjCAutoRefCount)
1598           DiagID = diag::err_method_not_found_with_typo;
1599         else
1600           DiagID = isClassMessage ? diag::warn_class_method_not_found_with_typo
1601                                   : diag::warn_instance_method_not_found_with_typo;
1602         Selector MatchedSel = OMD->getSelector();
1603         SourceRange SelectorRange(SelectorLocs.front(), SelectorLocs.back());
1604         if (MatchedSel.isUnarySelector())
1605           Diag(SelLoc, DiagID)
1606             << Sel<< isClassMessage << MatchedSel
1607             << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
1608         else
1609           Diag(SelLoc, DiagID) << Sel<< isClassMessage << MatchedSel;
1610       }
1611       else
1612         Diag(SelLoc, DiagID)
1613           << Sel << isClassMessage << SourceRange(SelectorLocs.front(),
1614                                                 SelectorLocs.back());
1615       // Find the class to which we are sending this message.
1616       if (ReceiverType->isObjCObjectPointerType()) {
1617         if (ObjCInterfaceDecl *ThisClass =
1618             ReceiverType->getAs<ObjCObjectPointerType>()->getInterfaceDecl()) {
1619           Diag(ThisClass->getLocation(), diag::note_receiver_class_declared);
1620           if (!RecRange.isInvalid())
1621             if (ThisClass->lookupClassMethod(Sel))
1622               Diag(RecRange.getBegin(),diag::note_receiver_expr_here)
1623                 << FixItHint::CreateReplacement(RecRange,
1624                                                 ThisClass->getNameAsString());
1625         }
1626       }
1627     }
1628 
1629     // In debuggers, we want to use __unknown_anytype for these
1630     // results so that clients can cast them.
1631     if (getLangOpts().DebuggerSupport) {
1632       ReturnType = Context.UnknownAnyTy;
1633     } else {
1634       ReturnType = Context.getObjCIdType();
1635     }
1636     VK = VK_RValue;
1637     return false;
1638   }
1639 
1640   ReturnType = getMessageSendResultType(Receiver, ReceiverType, Method,
1641                                         isClassMessage, isSuperMessage);
1642   VK = Expr::getValueKindForType(Method->getReturnType());
1643 
1644   unsigned NumNamedArgs = Sel.getNumArgs();
1645   // Method might have more arguments than selector indicates. This is due
1646   // to addition of c-style arguments in method.
1647   if (Method->param_size() > Sel.getNumArgs())
1648     NumNamedArgs = Method->param_size();
1649   // FIXME. This need be cleaned up.
1650   if (Args.size() < NumNamedArgs) {
1651     Diag(SelLoc, diag::err_typecheck_call_too_few_args)
1652       << 2 << NumNamedArgs << static_cast<unsigned>(Args.size());
1653     return false;
1654   }
1655 
1656   // Compute the set of type arguments to be substituted into each parameter
1657   // type.
1658   Optional<ArrayRef<QualType>> typeArgs
1659     = ReceiverType->getObjCSubstitutions(Method->getDeclContext());
1660   bool IsError = false;
1661   for (unsigned i = 0; i < NumNamedArgs; i++) {
1662     // We can't do any type-checking on a type-dependent argument.
1663     if (Args[i]->isTypeDependent())
1664       continue;
1665 
1666     Expr *argExpr = Args[i];
1667 
1668     ParmVarDecl *param = Method->parameters()[i];
1669     assert(argExpr && "CheckMessageArgumentTypes(): missing expression");
1670 
1671     if (param->hasAttr<NoEscapeAttr>())
1672       if (auto *BE = dyn_cast<BlockExpr>(
1673               argExpr->IgnoreParenNoopCasts(Context)))
1674         BE->getBlockDecl()->setDoesNotEscape();
1675 
1676     // Strip the unbridged-cast placeholder expression off unless it's
1677     // a consumed argument.
1678     if (argExpr->hasPlaceholderType(BuiltinType::ARCUnbridgedCast) &&
1679         !param->hasAttr<CFConsumedAttr>())
1680       argExpr = stripARCUnbridgedCast(argExpr);
1681 
1682     // If the parameter is __unknown_anytype, infer its type
1683     // from the argument.
1684     if (param->getType() == Context.UnknownAnyTy) {
1685       QualType paramType;
1686       ExprResult argE = checkUnknownAnyArg(SelLoc, argExpr, paramType);
1687       if (argE.isInvalid()) {
1688         IsError = true;
1689       } else {
1690         Args[i] = argE.get();
1691 
1692         // Update the parameter type in-place.
1693         param->setType(paramType);
1694       }
1695       continue;
1696     }
1697 
1698     QualType origParamType = param->getType();
1699     QualType paramType = param->getType();
1700     if (typeArgs)
1701       paramType = paramType.substObjCTypeArgs(
1702                     Context,
1703                     *typeArgs,
1704                     ObjCSubstitutionContext::Parameter);
1705 
1706     if (RequireCompleteType(argExpr->getSourceRange().getBegin(),
1707                             paramType,
1708                             diag::err_call_incomplete_argument, argExpr))
1709       return true;
1710 
1711     InitializedEntity Entity
1712       = InitializedEntity::InitializeParameter(Context, param, paramType);
1713     ExprResult ArgE = PerformCopyInitialization(Entity, SourceLocation(), argExpr);
1714     if (ArgE.isInvalid())
1715       IsError = true;
1716     else {
1717       Args[i] = ArgE.getAs<Expr>();
1718 
1719       // If we are type-erasing a block to a block-compatible
1720       // Objective-C pointer type, we may need to extend the lifetime
1721       // of the block object.
1722       if (typeArgs && Args[i]->isRValue() && paramType->isBlockPointerType() &&
1723           Args[i]->getType()->isBlockPointerType() &&
1724           origParamType->isObjCObjectPointerType()) {
1725         ExprResult arg = Args[i];
1726         maybeExtendBlockObject(arg);
1727         Args[i] = arg.get();
1728       }
1729     }
1730   }
1731 
1732   // Promote additional arguments to variadic methods.
1733   if (Method->isVariadic()) {
1734     for (unsigned i = NumNamedArgs, e = Args.size(); i < e; ++i) {
1735       if (Args[i]->isTypeDependent())
1736         continue;
1737 
1738       ExprResult Arg = DefaultVariadicArgumentPromotion(Args[i], VariadicMethod,
1739                                                         nullptr);
1740       IsError |= Arg.isInvalid();
1741       Args[i] = Arg.get();
1742     }
1743   } else {
1744     // Check for extra arguments to non-variadic methods.
1745     if (Args.size() != NumNamedArgs) {
1746       Diag(Args[NumNamedArgs]->getBeginLoc(),
1747            diag::err_typecheck_call_too_many_args)
1748           << 2 /*method*/ << NumNamedArgs << static_cast<unsigned>(Args.size())
1749           << Method->getSourceRange()
1750           << SourceRange(Args[NumNamedArgs]->getBeginLoc(),
1751                          Args.back()->getEndLoc());
1752     }
1753   }
1754 
1755   DiagnoseSentinelCalls(Method, SelLoc, Args);
1756 
1757   // Do additional checkings on method.
1758   IsError |= CheckObjCMethodCall(
1759       Method, SelLoc, makeArrayRef(Args.data(), Args.size()));
1760 
1761   return IsError;
1762 }
1763 
1764 bool Sema::isSelfExpr(Expr *RExpr) {
1765   // 'self' is objc 'self' in an objc method only.
1766   ObjCMethodDecl *Method =
1767       dyn_cast_or_null<ObjCMethodDecl>(CurContext->getNonClosureAncestor());
1768   return isSelfExpr(RExpr, Method);
1769 }
1770 
1771 bool Sema::isSelfExpr(Expr *receiver, const ObjCMethodDecl *method) {
1772   if (!method) return false;
1773 
1774   receiver = receiver->IgnoreParenLValueCasts();
1775   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(receiver))
1776     if (DRE->getDecl() == method->getSelfDecl())
1777       return true;
1778   return false;
1779 }
1780 
1781 /// LookupMethodInType - Look up a method in an ObjCObjectType.
1782 ObjCMethodDecl *Sema::LookupMethodInObjectType(Selector sel, QualType type,
1783                                                bool isInstance) {
1784   const ObjCObjectType *objType = type->castAs<ObjCObjectType>();
1785   if (ObjCInterfaceDecl *iface = objType->getInterface()) {
1786     // Look it up in the main interface (and categories, etc.)
1787     if (ObjCMethodDecl *method = iface->lookupMethod(sel, isInstance))
1788       return method;
1789 
1790     // Okay, look for "private" methods declared in any
1791     // @implementations we've seen.
1792     if (ObjCMethodDecl *method = iface->lookupPrivateMethod(sel, isInstance))
1793       return method;
1794   }
1795 
1796   // Check qualifiers.
1797   for (const auto *I : objType->quals())
1798     if (ObjCMethodDecl *method = I->lookupMethod(sel, isInstance))
1799       return method;
1800 
1801   return nullptr;
1802 }
1803 
1804 /// LookupMethodInQualifiedType - Lookups up a method in protocol qualifier
1805 /// list of a qualified objective pointer type.
1806 ObjCMethodDecl *Sema::LookupMethodInQualifiedType(Selector Sel,
1807                                               const ObjCObjectPointerType *OPT,
1808                                               bool Instance)
1809 {
1810   ObjCMethodDecl *MD = nullptr;
1811   for (const auto *PROTO : OPT->quals()) {
1812     if ((MD = PROTO->lookupMethod(Sel, Instance))) {
1813       return MD;
1814     }
1815   }
1816   return nullptr;
1817 }
1818 
1819 /// HandleExprPropertyRefExpr - Handle foo.bar where foo is a pointer to an
1820 /// objective C interface.  This is a property reference expression.
1821 ExprResult Sema::
1822 HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
1823                           Expr *BaseExpr, SourceLocation OpLoc,
1824                           DeclarationName MemberName,
1825                           SourceLocation MemberLoc,
1826                           SourceLocation SuperLoc, QualType SuperType,
1827                           bool Super) {
1828   const ObjCInterfaceType *IFaceT = OPT->getInterfaceType();
1829   ObjCInterfaceDecl *IFace = IFaceT->getDecl();
1830 
1831   if (!MemberName.isIdentifier()) {
1832     Diag(MemberLoc, diag::err_invalid_property_name)
1833       << MemberName << QualType(OPT, 0);
1834     return ExprError();
1835   }
1836 
1837   IdentifierInfo *Member = MemberName.getAsIdentifierInfo();
1838 
1839   SourceRange BaseRange = Super? SourceRange(SuperLoc)
1840                                : BaseExpr->getSourceRange();
1841   if (RequireCompleteType(MemberLoc, OPT->getPointeeType(),
1842                           diag::err_property_not_found_forward_class,
1843                           MemberName, BaseRange))
1844     return ExprError();
1845 
1846   if (ObjCPropertyDecl *PD = IFace->FindPropertyDeclaration(
1847           Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
1848     // Check whether we can reference this property.
1849     if (DiagnoseUseOfDecl(PD, MemberLoc))
1850       return ExprError();
1851     if (Super)
1852       return new (Context)
1853           ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
1854                               OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
1855     else
1856       return new (Context)
1857           ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
1858                               OK_ObjCProperty, MemberLoc, BaseExpr);
1859   }
1860   // Check protocols on qualified interfaces.
1861   for (const auto *I : OPT->quals())
1862     if (ObjCPropertyDecl *PD = I->FindPropertyDeclaration(
1863             Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
1864       // Check whether we can reference this property.
1865       if (DiagnoseUseOfDecl(PD, MemberLoc))
1866         return ExprError();
1867 
1868       if (Super)
1869         return new (Context) ObjCPropertyRefExpr(
1870             PD, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty, MemberLoc,
1871             SuperLoc, SuperType);
1872       else
1873         return new (Context)
1874             ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
1875                                 OK_ObjCProperty, MemberLoc, BaseExpr);
1876     }
1877   // If that failed, look for an "implicit" property by seeing if the nullary
1878   // selector is implemented.
1879 
1880   // FIXME: The logic for looking up nullary and unary selectors should be
1881   // shared with the code in ActOnInstanceMessage.
1882 
1883   Selector Sel = PP.getSelectorTable().getNullarySelector(Member);
1884   ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Sel);
1885 
1886   // May be found in property's qualified list.
1887   if (!Getter)
1888     Getter = LookupMethodInQualifiedType(Sel, OPT, true);
1889 
1890   // If this reference is in an @implementation, check for 'private' methods.
1891   if (!Getter)
1892     Getter = IFace->lookupPrivateMethod(Sel);
1893 
1894   if (Getter) {
1895     // Check if we can reference this property.
1896     if (DiagnoseUseOfDecl(Getter, MemberLoc))
1897       return ExprError();
1898   }
1899   // If we found a getter then this may be a valid dot-reference, we
1900   // will look for the matching setter, in case it is needed.
1901   Selector SetterSel =
1902     SelectorTable::constructSetterSelector(PP.getIdentifierTable(),
1903                                            PP.getSelectorTable(), Member);
1904   ObjCMethodDecl *Setter = IFace->lookupInstanceMethod(SetterSel);
1905 
1906   // May be found in property's qualified list.
1907   if (!Setter)
1908     Setter = LookupMethodInQualifiedType(SetterSel, OPT, true);
1909 
1910   if (!Setter) {
1911     // If this reference is in an @implementation, also check for 'private'
1912     // methods.
1913     Setter = IFace->lookupPrivateMethod(SetterSel);
1914   }
1915 
1916   if (Setter && DiagnoseUseOfDecl(Setter, MemberLoc))
1917     return ExprError();
1918 
1919   // Special warning if member name used in a property-dot for a setter accessor
1920   // does not use a property with same name; e.g. obj.X = ... for a property with
1921   // name 'x'.
1922   if (Setter && Setter->isImplicit() && Setter->isPropertyAccessor() &&
1923       !IFace->FindPropertyDeclaration(
1924           Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
1925       if (const ObjCPropertyDecl *PDecl = Setter->findPropertyDecl()) {
1926         // Do not warn if user is using property-dot syntax to make call to
1927         // user named setter.
1928         if (!(PDecl->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_setter))
1929           Diag(MemberLoc,
1930                diag::warn_property_access_suggest)
1931           << MemberName << QualType(OPT, 0) << PDecl->getName()
1932           << FixItHint::CreateReplacement(MemberLoc, PDecl->getName());
1933       }
1934   }
1935 
1936   if (Getter || Setter) {
1937     if (Super)
1938       return new (Context)
1939           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
1940                               OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
1941     else
1942       return new (Context)
1943           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
1944                               OK_ObjCProperty, MemberLoc, BaseExpr);
1945 
1946   }
1947 
1948   // Attempt to correct for typos in property names.
1949   DeclFilterCCC<ObjCPropertyDecl> CCC{};
1950   if (TypoCorrection Corrected = CorrectTypo(
1951           DeclarationNameInfo(MemberName, MemberLoc), LookupOrdinaryName,
1952           nullptr, nullptr, CCC, CTK_ErrorRecovery, IFace, false, OPT)) {
1953     DeclarationName TypoResult = Corrected.getCorrection();
1954     if (TypoResult.isIdentifier() &&
1955         TypoResult.getAsIdentifierInfo() == Member) {
1956       // There is no need to try the correction if it is the same.
1957       NamedDecl *ChosenDecl =
1958         Corrected.isKeyword() ? nullptr : Corrected.getFoundDecl();
1959       if (ChosenDecl && isa<ObjCPropertyDecl>(ChosenDecl))
1960         if (cast<ObjCPropertyDecl>(ChosenDecl)->isClassProperty()) {
1961           // This is a class property, we should not use the instance to
1962           // access it.
1963           Diag(MemberLoc, diag::err_class_property_found) << MemberName
1964           << OPT->getInterfaceDecl()->getName()
1965           << FixItHint::CreateReplacement(BaseExpr->getSourceRange(),
1966                                           OPT->getInterfaceDecl()->getName());
1967           return ExprError();
1968         }
1969     } else {
1970       diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
1971                                 << MemberName << QualType(OPT, 0));
1972       return HandleExprPropertyRefExpr(OPT, BaseExpr, OpLoc,
1973                                        TypoResult, MemberLoc,
1974                                        SuperLoc, SuperType, Super);
1975     }
1976   }
1977   ObjCInterfaceDecl *ClassDeclared;
1978   if (ObjCIvarDecl *Ivar =
1979       IFace->lookupInstanceVariable(Member, ClassDeclared)) {
1980     QualType T = Ivar->getType();
1981     if (const ObjCObjectPointerType * OBJPT =
1982         T->getAsObjCInterfacePointerType()) {
1983       if (RequireCompleteType(MemberLoc, OBJPT->getPointeeType(),
1984                               diag::err_property_not_as_forward_class,
1985                               MemberName, BaseExpr))
1986         return ExprError();
1987     }
1988     Diag(MemberLoc,
1989          diag::err_ivar_access_using_property_syntax_suggest)
1990     << MemberName << QualType(OPT, 0) << Ivar->getDeclName()
1991     << FixItHint::CreateReplacement(OpLoc, "->");
1992     return ExprError();
1993   }
1994 
1995   Diag(MemberLoc, diag::err_property_not_found)
1996     << MemberName << QualType(OPT, 0);
1997   if (Setter)
1998     Diag(Setter->getLocation(), diag::note_getter_unavailable)
1999           << MemberName << BaseExpr->getSourceRange();
2000   return ExprError();
2001 }
2002 
2003 ExprResult Sema::
2004 ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
2005                           IdentifierInfo &propertyName,
2006                           SourceLocation receiverNameLoc,
2007                           SourceLocation propertyNameLoc) {
2008 
2009   IdentifierInfo *receiverNamePtr = &receiverName;
2010   ObjCInterfaceDecl *IFace = getObjCInterfaceDecl(receiverNamePtr,
2011                                                   receiverNameLoc);
2012 
2013   QualType SuperType;
2014   if (!IFace) {
2015     // If the "receiver" is 'super' in a method, handle it as an expression-like
2016     // property reference.
2017     if (receiverNamePtr->isStr("super")) {
2018       if (ObjCMethodDecl *CurMethod = tryCaptureObjCSelf(receiverNameLoc)) {
2019         if (auto classDecl = CurMethod->getClassInterface()) {
2020           SuperType = QualType(classDecl->getSuperClassType(), 0);
2021           if (CurMethod->isInstanceMethod()) {
2022             if (SuperType.isNull()) {
2023               // The current class does not have a superclass.
2024               Diag(receiverNameLoc, diag::err_root_class_cannot_use_super)
2025                 << CurMethod->getClassInterface()->getIdentifier();
2026               return ExprError();
2027             }
2028             QualType T = Context.getObjCObjectPointerType(SuperType);
2029 
2030             return HandleExprPropertyRefExpr(T->castAs<ObjCObjectPointerType>(),
2031                                              /*BaseExpr*/nullptr,
2032                                              SourceLocation()/*OpLoc*/,
2033                                              &propertyName,
2034                                              propertyNameLoc,
2035                                              receiverNameLoc, T, true);
2036           }
2037 
2038           // Otherwise, if this is a class method, try dispatching to our
2039           // superclass.
2040           IFace = CurMethod->getClassInterface()->getSuperClass();
2041         }
2042       }
2043     }
2044 
2045     if (!IFace) {
2046       Diag(receiverNameLoc, diag::err_expected_either) << tok::identifier
2047                                                        << tok::l_paren;
2048       return ExprError();
2049     }
2050   }
2051 
2052   Selector GetterSel;
2053   Selector SetterSel;
2054   if (auto PD = IFace->FindPropertyDeclaration(
2055           &propertyName, ObjCPropertyQueryKind::OBJC_PR_query_class)) {
2056     GetterSel = PD->getGetterName();
2057     SetterSel = PD->getSetterName();
2058   } else {
2059     GetterSel = PP.getSelectorTable().getNullarySelector(&propertyName);
2060     SetterSel = SelectorTable::constructSetterSelector(
2061         PP.getIdentifierTable(), PP.getSelectorTable(), &propertyName);
2062   }
2063 
2064   // Search for a declared property first.
2065   ObjCMethodDecl *Getter = IFace->lookupClassMethod(GetterSel);
2066 
2067   // If this reference is in an @implementation, check for 'private' methods.
2068   if (!Getter)
2069     Getter = IFace->lookupPrivateClassMethod(GetterSel);
2070 
2071   if (Getter) {
2072     // FIXME: refactor/share with ActOnMemberReference().
2073     // Check if we can reference this property.
2074     if (DiagnoseUseOfDecl(Getter, propertyNameLoc))
2075       return ExprError();
2076   }
2077 
2078   // Look for the matching setter, in case it is needed.
2079   ObjCMethodDecl *Setter = IFace->lookupClassMethod(SetterSel);
2080   if (!Setter) {
2081     // If this reference is in an @implementation, also check for 'private'
2082     // methods.
2083     Setter = IFace->lookupPrivateClassMethod(SetterSel);
2084   }
2085   // Look through local category implementations associated with the class.
2086   if (!Setter)
2087     Setter = IFace->getCategoryClassMethod(SetterSel);
2088 
2089   if (Setter && DiagnoseUseOfDecl(Setter, propertyNameLoc))
2090     return ExprError();
2091 
2092   if (Getter || Setter) {
2093     if (!SuperType.isNull())
2094       return new (Context)
2095           ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
2096                               OK_ObjCProperty, propertyNameLoc, receiverNameLoc,
2097                               SuperType);
2098 
2099     return new (Context) ObjCPropertyRefExpr(
2100         Getter, Setter, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty,
2101         propertyNameLoc, receiverNameLoc, IFace);
2102   }
2103   return ExprError(Diag(propertyNameLoc, diag::err_property_not_found)
2104                      << &propertyName << Context.getObjCInterfaceType(IFace));
2105 }
2106 
2107 namespace {
2108 
2109 class ObjCInterfaceOrSuperCCC final : public CorrectionCandidateCallback {
2110  public:
2111   ObjCInterfaceOrSuperCCC(ObjCMethodDecl *Method) {
2112     // Determine whether "super" is acceptable in the current context.
2113     if (Method && Method->getClassInterface())
2114       WantObjCSuper = Method->getClassInterface()->getSuperClass();
2115   }
2116 
2117   bool ValidateCandidate(const TypoCorrection &candidate) override {
2118     return candidate.getCorrectionDeclAs<ObjCInterfaceDecl>() ||
2119         candidate.isKeyword("super");
2120   }
2121 
2122   std::unique_ptr<CorrectionCandidateCallback> clone() override {
2123     return llvm::make_unique<ObjCInterfaceOrSuperCCC>(*this);
2124   }
2125 };
2126 
2127 } // end anonymous namespace
2128 
2129 Sema::ObjCMessageKind Sema::getObjCMessageKind(Scope *S,
2130                                                IdentifierInfo *Name,
2131                                                SourceLocation NameLoc,
2132                                                bool IsSuper,
2133                                                bool HasTrailingDot,
2134                                                ParsedType &ReceiverType) {
2135   ReceiverType = nullptr;
2136 
2137   // If the identifier is "super" and there is no trailing dot, we're
2138   // messaging super. If the identifier is "super" and there is a
2139   // trailing dot, it's an instance message.
2140   if (IsSuper && S->isInObjcMethodScope())
2141     return HasTrailingDot? ObjCInstanceMessage : ObjCSuperMessage;
2142 
2143   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
2144   LookupName(Result, S);
2145 
2146   switch (Result.getResultKind()) {
2147   case LookupResult::NotFound:
2148     // Normal name lookup didn't find anything. If we're in an
2149     // Objective-C method, look for ivars. If we find one, we're done!
2150     // FIXME: This is a hack. Ivar lookup should be part of normal
2151     // lookup.
2152     if (ObjCMethodDecl *Method = getCurMethodDecl()) {
2153       if (!Method->getClassInterface()) {
2154         // Fall back: let the parser try to parse it as an instance message.
2155         return ObjCInstanceMessage;
2156       }
2157 
2158       ObjCInterfaceDecl *ClassDeclared;
2159       if (Method->getClassInterface()->lookupInstanceVariable(Name,
2160                                                               ClassDeclared))
2161         return ObjCInstanceMessage;
2162     }
2163 
2164     // Break out; we'll perform typo correction below.
2165     break;
2166 
2167   case LookupResult::NotFoundInCurrentInstantiation:
2168   case LookupResult::FoundOverloaded:
2169   case LookupResult::FoundUnresolvedValue:
2170   case LookupResult::Ambiguous:
2171     Result.suppressDiagnostics();
2172     return ObjCInstanceMessage;
2173 
2174   case LookupResult::Found: {
2175     // If the identifier is a class or not, and there is a trailing dot,
2176     // it's an instance message.
2177     if (HasTrailingDot)
2178       return ObjCInstanceMessage;
2179     // We found something. If it's a type, then we have a class
2180     // message. Otherwise, it's an instance message.
2181     NamedDecl *ND = Result.getFoundDecl();
2182     QualType T;
2183     if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(ND))
2184       T = Context.getObjCInterfaceType(Class);
2185     else if (TypeDecl *Type = dyn_cast<TypeDecl>(ND)) {
2186       T = Context.getTypeDeclType(Type);
2187       DiagnoseUseOfDecl(Type, NameLoc);
2188     }
2189     else
2190       return ObjCInstanceMessage;
2191 
2192     //  We have a class message, and T is the type we're
2193     //  messaging. Build source-location information for it.
2194     TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
2195     ReceiverType = CreateParsedType(T, TSInfo);
2196     return ObjCClassMessage;
2197   }
2198   }
2199 
2200   ObjCInterfaceOrSuperCCC CCC(getCurMethodDecl());
2201   if (TypoCorrection Corrected = CorrectTypo(
2202           Result.getLookupNameInfo(), Result.getLookupKind(), S, nullptr, CCC,
2203           CTK_ErrorRecovery, nullptr, false, nullptr, false)) {
2204     if (Corrected.isKeyword()) {
2205       // If we've found the keyword "super" (the only keyword that would be
2206       // returned by CorrectTypo), this is a send to super.
2207       diagnoseTypo(Corrected,
2208                    PDiag(diag::err_unknown_receiver_suggest) << Name);
2209       return ObjCSuperMessage;
2210     } else if (ObjCInterfaceDecl *Class =
2211                    Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
2212       // If we found a declaration, correct when it refers to an Objective-C
2213       // class.
2214       diagnoseTypo(Corrected,
2215                    PDiag(diag::err_unknown_receiver_suggest) << Name);
2216       QualType T = Context.getObjCInterfaceType(Class);
2217       TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
2218       ReceiverType = CreateParsedType(T, TSInfo);
2219       return ObjCClassMessage;
2220     }
2221   }
2222 
2223   // Fall back: let the parser try to parse it as an instance message.
2224   return ObjCInstanceMessage;
2225 }
2226 
2227 ExprResult Sema::ActOnSuperMessage(Scope *S,
2228                                    SourceLocation SuperLoc,
2229                                    Selector Sel,
2230                                    SourceLocation LBracLoc,
2231                                    ArrayRef<SourceLocation> SelectorLocs,
2232                                    SourceLocation RBracLoc,
2233                                    MultiExprArg Args) {
2234   // Determine whether we are inside a method or not.
2235   ObjCMethodDecl *Method = tryCaptureObjCSelf(SuperLoc);
2236   if (!Method) {
2237     Diag(SuperLoc, diag::err_invalid_receiver_to_message_super);
2238     return ExprError();
2239   }
2240 
2241   ObjCInterfaceDecl *Class = Method->getClassInterface();
2242   if (!Class) {
2243     Diag(SuperLoc, diag::err_no_super_class_message)
2244       << Method->getDeclName();
2245     return ExprError();
2246   }
2247 
2248   QualType SuperTy(Class->getSuperClassType(), 0);
2249   if (SuperTy.isNull()) {
2250     // The current class does not have a superclass.
2251     Diag(SuperLoc, diag::err_root_class_cannot_use_super)
2252       << Class->getIdentifier();
2253     return ExprError();
2254   }
2255 
2256   // We are in a method whose class has a superclass, so 'super'
2257   // is acting as a keyword.
2258   if (Method->getSelector() == Sel)
2259     getCurFunction()->ObjCShouldCallSuper = false;
2260 
2261   if (Method->isInstanceMethod()) {
2262     // Since we are in an instance method, this is an instance
2263     // message to the superclass instance.
2264     SuperTy = Context.getObjCObjectPointerType(SuperTy);
2265     return BuildInstanceMessage(nullptr, SuperTy, SuperLoc,
2266                                 Sel, /*Method=*/nullptr,
2267                                 LBracLoc, SelectorLocs, RBracLoc, Args);
2268   }
2269 
2270   // Since we are in a class method, this is a class message to
2271   // the superclass.
2272   return BuildClassMessage(/*ReceiverTypeInfo=*/nullptr,
2273                            SuperTy,
2274                            SuperLoc, Sel, /*Method=*/nullptr,
2275                            LBracLoc, SelectorLocs, RBracLoc, Args);
2276 }
2277 
2278 ExprResult Sema::BuildClassMessageImplicit(QualType ReceiverType,
2279                                            bool isSuperReceiver,
2280                                            SourceLocation Loc,
2281                                            Selector Sel,
2282                                            ObjCMethodDecl *Method,
2283                                            MultiExprArg Args) {
2284   TypeSourceInfo *receiverTypeInfo = nullptr;
2285   if (!ReceiverType.isNull())
2286     receiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType);
2287 
2288   return BuildClassMessage(receiverTypeInfo, ReceiverType,
2289                           /*SuperLoc=*/isSuperReceiver ? Loc : SourceLocation(),
2290                            Sel, Method, Loc, Loc, Loc, Args,
2291                            /*isImplicit=*/true);
2292 }
2293 
2294 static void applyCocoaAPICheck(Sema &S, const ObjCMessageExpr *Msg,
2295                                unsigned DiagID,
2296                                bool (*refactor)(const ObjCMessageExpr *,
2297                                               const NSAPI &, edit::Commit &)) {
2298   SourceLocation MsgLoc = Msg->getExprLoc();
2299   if (S.Diags.isIgnored(DiagID, MsgLoc))
2300     return;
2301 
2302   SourceManager &SM = S.SourceMgr;
2303   edit::Commit ECommit(SM, S.LangOpts);
2304   if (refactor(Msg,*S.NSAPIObj, ECommit)) {
2305     DiagnosticBuilder Builder = S.Diag(MsgLoc, DiagID)
2306                         << Msg->getSelector() << Msg->getSourceRange();
2307     // FIXME: Don't emit diagnostic at all if fixits are non-commitable.
2308     if (!ECommit.isCommitable())
2309       return;
2310     for (edit::Commit::edit_iterator
2311            I = ECommit.edit_begin(), E = ECommit.edit_end(); I != E; ++I) {
2312       const edit::Commit::Edit &Edit = *I;
2313       switch (Edit.Kind) {
2314       case edit::Commit::Act_Insert:
2315         Builder.AddFixItHint(FixItHint::CreateInsertion(Edit.OrigLoc,
2316                                                         Edit.Text,
2317                                                         Edit.BeforePrev));
2318         break;
2319       case edit::Commit::Act_InsertFromRange:
2320         Builder.AddFixItHint(
2321             FixItHint::CreateInsertionFromRange(Edit.OrigLoc,
2322                                                 Edit.getInsertFromRange(SM),
2323                                                 Edit.BeforePrev));
2324         break;
2325       case edit::Commit::Act_Remove:
2326         Builder.AddFixItHint(FixItHint::CreateRemoval(Edit.getFileRange(SM)));
2327         break;
2328       }
2329     }
2330   }
2331 }
2332 
2333 static void checkCocoaAPI(Sema &S, const ObjCMessageExpr *Msg) {
2334   applyCocoaAPICheck(S, Msg, diag::warn_objc_redundant_literal_use,
2335                      edit::rewriteObjCRedundantCallWithLiteral);
2336 }
2337 
2338 static void checkFoundationAPI(Sema &S, SourceLocation Loc,
2339                                const ObjCMethodDecl *Method,
2340                                ArrayRef<Expr *> Args, QualType ReceiverType,
2341                                bool IsClassObjectCall) {
2342   // Check if this is a performSelector method that uses a selector that returns
2343   // a record or a vector type.
2344   if (Method->getSelector().getMethodFamily() != OMF_performSelector ||
2345       Args.empty())
2346     return;
2347   const auto *SE = dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens());
2348   if (!SE)
2349     return;
2350   ObjCMethodDecl *ImpliedMethod;
2351   if (!IsClassObjectCall) {
2352     const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>();
2353     if (!OPT || !OPT->getInterfaceDecl())
2354       return;
2355     ImpliedMethod =
2356         OPT->getInterfaceDecl()->lookupInstanceMethod(SE->getSelector());
2357     if (!ImpliedMethod)
2358       ImpliedMethod =
2359           OPT->getInterfaceDecl()->lookupPrivateMethod(SE->getSelector());
2360   } else {
2361     const auto *IT = ReceiverType->getAs<ObjCInterfaceType>();
2362     if (!IT)
2363       return;
2364     ImpliedMethod = IT->getDecl()->lookupClassMethod(SE->getSelector());
2365     if (!ImpliedMethod)
2366       ImpliedMethod =
2367           IT->getDecl()->lookupPrivateClassMethod(SE->getSelector());
2368   }
2369   if (!ImpliedMethod)
2370     return;
2371   QualType Ret = ImpliedMethod->getReturnType();
2372   if (Ret->isRecordType() || Ret->isVectorType() || Ret->isExtVectorType()) {
2373     QualType Ret = ImpliedMethod->getReturnType();
2374     S.Diag(Loc, diag::warn_objc_unsafe_perform_selector)
2375         << Method->getSelector()
2376         << (!Ret->isRecordType()
2377                 ? /*Vector*/ 2
2378                 : Ret->isUnionType() ? /*Union*/ 1 : /*Struct*/ 0);
2379     S.Diag(ImpliedMethod->getBeginLoc(),
2380            diag::note_objc_unsafe_perform_selector_method_declared_here)
2381         << ImpliedMethod->getSelector() << Ret;
2382   }
2383 }
2384 
2385 /// Diagnose use of %s directive in an NSString which is being passed
2386 /// as formatting string to formatting method.
2387 static void
2388 DiagnoseCStringFormatDirectiveInObjCAPI(Sema &S,
2389                                         ObjCMethodDecl *Method,
2390                                         Selector Sel,
2391                                         Expr **Args, unsigned NumArgs) {
2392   unsigned Idx = 0;
2393   bool Format = false;
2394   ObjCStringFormatFamily SFFamily = Sel.getStringFormatFamily();
2395   if (SFFamily == ObjCStringFormatFamily::SFF_NSString) {
2396     Idx = 0;
2397     Format = true;
2398   }
2399   else if (Method) {
2400     for (const auto *I : Method->specific_attrs<FormatAttr>()) {
2401       if (S.GetFormatNSStringIdx(I, Idx)) {
2402         Format = true;
2403         break;
2404       }
2405     }
2406   }
2407   if (!Format || NumArgs <= Idx)
2408     return;
2409 
2410   Expr *FormatExpr = Args[Idx];
2411   if (ObjCStringLiteral *OSL =
2412       dyn_cast<ObjCStringLiteral>(FormatExpr->IgnoreParenImpCasts())) {
2413     StringLiteral *FormatString = OSL->getString();
2414     if (S.FormatStringHasSArg(FormatString)) {
2415       S.Diag(FormatExpr->getExprLoc(), diag::warn_objc_cdirective_format_string)
2416         << "%s" << 0 << 0;
2417       if (Method)
2418         S.Diag(Method->getLocation(), diag::note_method_declared_at)
2419           << Method->getDeclName();
2420     }
2421   }
2422 }
2423 
2424 /// Build an Objective-C class message expression.
2425 ///
2426 /// This routine takes care of both normal class messages and
2427 /// class messages to the superclass.
2428 ///
2429 /// \param ReceiverTypeInfo Type source information that describes the
2430 /// receiver of this message. This may be NULL, in which case we are
2431 /// sending to the superclass and \p SuperLoc must be a valid source
2432 /// location.
2433 
2434 /// \param ReceiverType The type of the object receiving the
2435 /// message. When \p ReceiverTypeInfo is non-NULL, this is the same
2436 /// type as that refers to. For a superclass send, this is the type of
2437 /// the superclass.
2438 ///
2439 /// \param SuperLoc The location of the "super" keyword in a
2440 /// superclass message.
2441 ///
2442 /// \param Sel The selector to which the message is being sent.
2443 ///
2444 /// \param Method The method that this class message is invoking, if
2445 /// already known.
2446 ///
2447 /// \param LBracLoc The location of the opening square bracket ']'.
2448 ///
2449 /// \param RBracLoc The location of the closing square bracket ']'.
2450 ///
2451 /// \param ArgsIn The message arguments.
2452 ExprResult Sema::BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
2453                                    QualType ReceiverType,
2454                                    SourceLocation SuperLoc,
2455                                    Selector Sel,
2456                                    ObjCMethodDecl *Method,
2457                                    SourceLocation LBracLoc,
2458                                    ArrayRef<SourceLocation> SelectorLocs,
2459                                    SourceLocation RBracLoc,
2460                                    MultiExprArg ArgsIn,
2461                                    bool isImplicit) {
2462   SourceLocation Loc = SuperLoc.isValid()? SuperLoc
2463     : ReceiverTypeInfo->getTypeLoc().getSourceRange().getBegin();
2464   if (LBracLoc.isInvalid()) {
2465     Diag(Loc, diag::err_missing_open_square_message_send)
2466       << FixItHint::CreateInsertion(Loc, "[");
2467     LBracLoc = Loc;
2468   }
2469   ArrayRef<SourceLocation> SelectorSlotLocs;
2470   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
2471     SelectorSlotLocs = SelectorLocs;
2472   else
2473     SelectorSlotLocs = Loc;
2474   SourceLocation SelLoc = SelectorSlotLocs.front();
2475 
2476   if (ReceiverType->isDependentType()) {
2477     // If the receiver type is dependent, we can't type-check anything
2478     // at this point. Build a dependent expression.
2479     unsigned NumArgs = ArgsIn.size();
2480     Expr **Args = ArgsIn.data();
2481     assert(SuperLoc.isInvalid() && "Message to super with dependent type");
2482     return ObjCMessageExpr::Create(
2483         Context, ReceiverType, VK_RValue, LBracLoc, ReceiverTypeInfo, Sel,
2484         SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs), RBracLoc,
2485         isImplicit);
2486   }
2487 
2488   // Find the class to which we are sending this message.
2489   ObjCInterfaceDecl *Class = nullptr;
2490   const ObjCObjectType *ClassType = ReceiverType->getAs<ObjCObjectType>();
2491   if (!ClassType || !(Class = ClassType->getInterface())) {
2492     Diag(Loc, diag::err_invalid_receiver_class_message)
2493       << ReceiverType;
2494     return ExprError();
2495   }
2496   assert(Class && "We don't know which class we're messaging?");
2497   // objc++ diagnoses during typename annotation.
2498   if (!getLangOpts().CPlusPlus)
2499     (void)DiagnoseUseOfDecl(Class, SelectorSlotLocs);
2500   // Find the method we are messaging.
2501   if (!Method) {
2502     SourceRange TypeRange
2503       = SuperLoc.isValid()? SourceRange(SuperLoc)
2504                           : ReceiverTypeInfo->getTypeLoc().getSourceRange();
2505     if (RequireCompleteType(Loc, Context.getObjCInterfaceType(Class),
2506                             (getLangOpts().ObjCAutoRefCount
2507                                ? diag::err_arc_receiver_forward_class
2508                                : diag::warn_receiver_forward_class),
2509                             TypeRange)) {
2510       // A forward class used in messaging is treated as a 'Class'
2511       Method = LookupFactoryMethodInGlobalPool(Sel,
2512                                                SourceRange(LBracLoc, RBracLoc));
2513       if (Method && !getLangOpts().ObjCAutoRefCount)
2514         Diag(Method->getLocation(), diag::note_method_sent_forward_class)
2515           << Method->getDeclName();
2516     }
2517     if (!Method)
2518       Method = Class->lookupClassMethod(Sel);
2519 
2520     // If we have an implementation in scope, check "private" methods.
2521     if (!Method)
2522       Method = Class->lookupPrivateClassMethod(Sel);
2523 
2524     if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs,
2525                                     nullptr, false, false, Class))
2526       return ExprError();
2527   }
2528 
2529   // Check the argument types and determine the result type.
2530   QualType ReturnType;
2531   ExprValueKind VK = VK_RValue;
2532 
2533   unsigned NumArgs = ArgsIn.size();
2534   Expr **Args = ArgsIn.data();
2535   if (CheckMessageArgumentTypes(/*Receiver=*/nullptr, ReceiverType,
2536                                 MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
2537                                 Method, true, SuperLoc.isValid(), LBracLoc,
2538                                 RBracLoc, SourceRange(), ReturnType, VK))
2539     return ExprError();
2540 
2541   if (Method && !Method->getReturnType()->isVoidType() &&
2542       RequireCompleteType(LBracLoc, Method->getReturnType(),
2543                           diag::err_illegal_message_expr_incomplete_type))
2544     return ExprError();
2545 
2546   // Warn about explicit call of +initialize on its own class. But not on 'super'.
2547   if (Method && Method->getMethodFamily() == OMF_initialize) {
2548     if (!SuperLoc.isValid()) {
2549       const ObjCInterfaceDecl *ID =
2550         dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext());
2551       if (ID == Class) {
2552         Diag(Loc, diag::warn_direct_initialize_call);
2553         Diag(Method->getLocation(), diag::note_method_declared_at)
2554           << Method->getDeclName();
2555       }
2556     }
2557     else if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
2558       // [super initialize] is allowed only within an +initialize implementation
2559       if (CurMeth->getMethodFamily() != OMF_initialize) {
2560         Diag(Loc, diag::warn_direct_super_initialize_call);
2561         Diag(Method->getLocation(), diag::note_method_declared_at)
2562           << Method->getDeclName();
2563         Diag(CurMeth->getLocation(), diag::note_method_declared_at)
2564         << CurMeth->getDeclName();
2565       }
2566     }
2567   }
2568 
2569   DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
2570 
2571   // Construct the appropriate ObjCMessageExpr.
2572   ObjCMessageExpr *Result;
2573   if (SuperLoc.isValid())
2574     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
2575                                      SuperLoc, /*IsInstanceSuper=*/false,
2576                                      ReceiverType, Sel, SelectorLocs,
2577                                      Method, makeArrayRef(Args, NumArgs),
2578                                      RBracLoc, isImplicit);
2579   else {
2580     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
2581                                      ReceiverTypeInfo, Sel, SelectorLocs,
2582                                      Method, makeArrayRef(Args, NumArgs),
2583                                      RBracLoc, isImplicit);
2584     if (!isImplicit)
2585       checkCocoaAPI(*this, Result);
2586   }
2587   if (Method)
2588     checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
2589                        ReceiverType, /*IsClassObjectCall=*/true);
2590   return MaybeBindToTemporary(Result);
2591 }
2592 
2593 // ActOnClassMessage - used for both unary and keyword messages.
2594 // ArgExprs is optional - if it is present, the number of expressions
2595 // is obtained from Sel.getNumArgs().
2596 ExprResult Sema::ActOnClassMessage(Scope *S,
2597                                    ParsedType Receiver,
2598                                    Selector Sel,
2599                                    SourceLocation LBracLoc,
2600                                    ArrayRef<SourceLocation> SelectorLocs,
2601                                    SourceLocation RBracLoc,
2602                                    MultiExprArg Args) {
2603   TypeSourceInfo *ReceiverTypeInfo;
2604   QualType ReceiverType = GetTypeFromParser(Receiver, &ReceiverTypeInfo);
2605   if (ReceiverType.isNull())
2606     return ExprError();
2607 
2608   if (!ReceiverTypeInfo)
2609     ReceiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType, LBracLoc);
2610 
2611   return BuildClassMessage(ReceiverTypeInfo, ReceiverType,
2612                            /*SuperLoc=*/SourceLocation(), Sel,
2613                            /*Method=*/nullptr, LBracLoc, SelectorLocs, RBracLoc,
2614                            Args);
2615 }
2616 
2617 ExprResult Sema::BuildInstanceMessageImplicit(Expr *Receiver,
2618                                               QualType ReceiverType,
2619                                               SourceLocation Loc,
2620                                               Selector Sel,
2621                                               ObjCMethodDecl *Method,
2622                                               MultiExprArg Args) {
2623   return BuildInstanceMessage(Receiver, ReceiverType,
2624                               /*SuperLoc=*/!Receiver ? Loc : SourceLocation(),
2625                               Sel, Method, Loc, Loc, Loc, Args,
2626                               /*isImplicit=*/true);
2627 }
2628 
2629 static bool isMethodDeclaredInRootProtocol(Sema &S, const ObjCMethodDecl *M) {
2630   if (!S.NSAPIObj)
2631     return false;
2632   const auto *Protocol = dyn_cast<ObjCProtocolDecl>(M->getDeclContext());
2633   if (!Protocol)
2634     return false;
2635   const IdentifierInfo *II = S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
2636   if (const auto *RootClass = dyn_cast_or_null<ObjCInterfaceDecl>(
2637           S.LookupSingleName(S.TUScope, II, Protocol->getBeginLoc(),
2638                              Sema::LookupOrdinaryName))) {
2639     for (const ObjCProtocolDecl *P : RootClass->all_referenced_protocols()) {
2640       if (P->getCanonicalDecl() == Protocol->getCanonicalDecl())
2641         return true;
2642     }
2643   }
2644   return false;
2645 }
2646 
2647 /// Build an Objective-C instance message expression.
2648 ///
2649 /// This routine takes care of both normal instance messages and
2650 /// instance messages to the superclass instance.
2651 ///
2652 /// \param Receiver The expression that computes the object that will
2653 /// receive this message. This may be empty, in which case we are
2654 /// sending to the superclass instance and \p SuperLoc must be a valid
2655 /// source location.
2656 ///
2657 /// \param ReceiverType The (static) type of the object receiving the
2658 /// message. When a \p Receiver expression is provided, this is the
2659 /// same type as that expression. For a superclass instance send, this
2660 /// is a pointer to the type of the superclass.
2661 ///
2662 /// \param SuperLoc The location of the "super" keyword in a
2663 /// superclass instance message.
2664 ///
2665 /// \param Sel The selector to which the message is being sent.
2666 ///
2667 /// \param Method The method that this instance message is invoking, if
2668 /// already known.
2669 ///
2670 /// \param LBracLoc The location of the opening square bracket ']'.
2671 ///
2672 /// \param RBracLoc The location of the closing square bracket ']'.
2673 ///
2674 /// \param ArgsIn The message arguments.
2675 ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
2676                                       QualType ReceiverType,
2677                                       SourceLocation SuperLoc,
2678                                       Selector Sel,
2679                                       ObjCMethodDecl *Method,
2680                                       SourceLocation LBracLoc,
2681                                       ArrayRef<SourceLocation> SelectorLocs,
2682                                       SourceLocation RBracLoc,
2683                                       MultiExprArg ArgsIn,
2684                                       bool isImplicit) {
2685   assert((Receiver || SuperLoc.isValid()) && "If the Receiver is null, the "
2686                                              "SuperLoc must be valid so we can "
2687                                              "use it instead.");
2688 
2689   // The location of the receiver.
2690   SourceLocation Loc = SuperLoc.isValid() ? SuperLoc : Receiver->getBeginLoc();
2691   SourceRange RecRange =
2692       SuperLoc.isValid()? SuperLoc : Receiver->getSourceRange();
2693   ArrayRef<SourceLocation> SelectorSlotLocs;
2694   if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
2695     SelectorSlotLocs = SelectorLocs;
2696   else
2697     SelectorSlotLocs = Loc;
2698   SourceLocation SelLoc = SelectorSlotLocs.front();
2699 
2700   if (LBracLoc.isInvalid()) {
2701     Diag(Loc, diag::err_missing_open_square_message_send)
2702       << FixItHint::CreateInsertion(Loc, "[");
2703     LBracLoc = Loc;
2704   }
2705 
2706   // If we have a receiver expression, perform appropriate promotions
2707   // and determine receiver type.
2708   if (Receiver) {
2709     if (Receiver->hasPlaceholderType()) {
2710       ExprResult Result;
2711       if (Receiver->getType() == Context.UnknownAnyTy)
2712         Result = forceUnknownAnyToType(Receiver, Context.getObjCIdType());
2713       else
2714         Result = CheckPlaceholderExpr(Receiver);
2715       if (Result.isInvalid()) return ExprError();
2716       Receiver = Result.get();
2717     }
2718 
2719     if (Receiver->isTypeDependent()) {
2720       // If the receiver is type-dependent, we can't type-check anything
2721       // at this point. Build a dependent expression.
2722       unsigned NumArgs = ArgsIn.size();
2723       Expr **Args = ArgsIn.data();
2724       assert(SuperLoc.isInvalid() && "Message to super with dependent type");
2725       return ObjCMessageExpr::Create(
2726           Context, Context.DependentTy, VK_RValue, LBracLoc, Receiver, Sel,
2727           SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs),
2728           RBracLoc, isImplicit);
2729     }
2730 
2731     // If necessary, apply function/array conversion to the receiver.
2732     // C99 6.7.5.3p[7,8].
2733     ExprResult Result = DefaultFunctionArrayLvalueConversion(Receiver);
2734     if (Result.isInvalid())
2735       return ExprError();
2736     Receiver = Result.get();
2737     ReceiverType = Receiver->getType();
2738 
2739     // If the receiver is an ObjC pointer, a block pointer, or an
2740     // __attribute__((NSObject)) pointer, we don't need to do any
2741     // special conversion in order to look up a receiver.
2742     if (ReceiverType->isObjCRetainableType()) {
2743       // do nothing
2744     } else if (!getLangOpts().ObjCAutoRefCount &&
2745                !Context.getObjCIdType().isNull() &&
2746                (ReceiverType->isPointerType() ||
2747                 ReceiverType->isIntegerType())) {
2748       // Implicitly convert integers and pointers to 'id' but emit a warning.
2749       // But not in ARC.
2750       Diag(Loc, diag::warn_bad_receiver_type)
2751         << ReceiverType
2752         << Receiver->getSourceRange();
2753       if (ReceiverType->isPointerType()) {
2754         Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
2755                                      CK_CPointerToObjCPointerCast).get();
2756       } else {
2757         // TODO: specialized warning on null receivers?
2758         bool IsNull = Receiver->isNullPointerConstant(Context,
2759                                               Expr::NPC_ValueDependentIsNull);
2760         CastKind Kind = IsNull ? CK_NullToPointer : CK_IntegralToPointer;
2761         Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
2762                                      Kind).get();
2763       }
2764       ReceiverType = Receiver->getType();
2765     } else if (getLangOpts().CPlusPlus) {
2766       // The receiver must be a complete type.
2767       if (RequireCompleteType(Loc, Receiver->getType(),
2768                               diag::err_incomplete_receiver_type))
2769         return ExprError();
2770 
2771       ExprResult result = PerformContextuallyConvertToObjCPointer(Receiver);
2772       if (result.isUsable()) {
2773         Receiver = result.get();
2774         ReceiverType = Receiver->getType();
2775       }
2776     }
2777   }
2778 
2779   if (ReceiverType->isObjCIdType() && !isImplicit)
2780     Diag(Receiver->getExprLoc(), diag::warn_messaging_unqualified_id);
2781 
2782   // There's a somewhat weird interaction here where we assume that we
2783   // won't actually have a method unless we also don't need to do some
2784   // of the more detailed type-checking on the receiver.
2785 
2786   if (!Method) {
2787     // Handle messages to id and __kindof types (where we use the
2788     // global method pool).
2789     const ObjCObjectType *typeBound = nullptr;
2790     bool receiverIsIdLike = ReceiverType->isObjCIdOrObjectKindOfType(Context,
2791                                                                      typeBound);
2792     if (receiverIsIdLike || ReceiverType->isBlockPointerType() ||
2793         (Receiver && Context.isObjCNSObjectType(Receiver->getType()))) {
2794       SmallVector<ObjCMethodDecl*, 4> Methods;
2795       // If we have a type bound, further filter the methods.
2796       CollectMultipleMethodsInGlobalPool(Sel, Methods, true/*InstanceFirst*/,
2797                                          true/*CheckTheOther*/, typeBound);
2798       if (!Methods.empty()) {
2799         // We choose the first method as the initial candidate, then try to
2800         // select a better one.
2801         Method = Methods[0];
2802 
2803         if (ObjCMethodDecl *BestMethod =
2804             SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(), Methods))
2805           Method = BestMethod;
2806 
2807         if (!AreMultipleMethodsInGlobalPool(Sel, Method,
2808                                             SourceRange(LBracLoc, RBracLoc),
2809                                             receiverIsIdLike, Methods))
2810           DiagnoseUseOfDecl(Method, SelectorSlotLocs);
2811       }
2812     } else if (ReceiverType->isObjCClassOrClassKindOfType() ||
2813                ReceiverType->isObjCQualifiedClassType()) {
2814       // Handle messages to Class.
2815       // We allow sending a message to a qualified Class ("Class<foo>"), which
2816       // is ok as long as one of the protocols implements the selector (if not,
2817       // warn).
2818       if (!ReceiverType->isObjCClassOrClassKindOfType()) {
2819         const ObjCObjectPointerType *QClassTy
2820           = ReceiverType->getAsObjCQualifiedClassType();
2821         // Search protocols for class methods.
2822         Method = LookupMethodInQualifiedType(Sel, QClassTy, false);
2823         if (!Method) {
2824           Method = LookupMethodInQualifiedType(Sel, QClassTy, true);
2825           // warn if instance method found for a Class message.
2826           if (Method && !isMethodDeclaredInRootProtocol(*this, Method)) {
2827             Diag(SelLoc, diag::warn_instance_method_on_class_found)
2828               << Method->getSelector() << Sel;
2829             Diag(Method->getLocation(), diag::note_method_declared_at)
2830               << Method->getDeclName();
2831           }
2832         }
2833       } else {
2834         if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
2835           if (ObjCInterfaceDecl *ClassDecl = CurMeth->getClassInterface()) {
2836             // As a guess, try looking for the method in the current interface.
2837             // This very well may not produce the "right" method.
2838 
2839             // First check the public methods in the class interface.
2840             Method = ClassDecl->lookupClassMethod(Sel);
2841 
2842             if (!Method)
2843               Method = ClassDecl->lookupPrivateClassMethod(Sel);
2844 
2845             if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
2846               return ExprError();
2847           }
2848         }
2849         if (!Method) {
2850           // If not messaging 'self', look for any factory method named 'Sel'.
2851           if (!Receiver || !isSelfExpr(Receiver)) {
2852             // If no class (factory) method was found, check if an _instance_
2853             // method of the same name exists in the root class only.
2854             SmallVector<ObjCMethodDecl*, 4> Methods;
2855             CollectMultipleMethodsInGlobalPool(Sel, Methods,
2856                                                false/*InstanceFirst*/,
2857                                                true/*CheckTheOther*/);
2858             if (!Methods.empty()) {
2859               // We choose the first method as the initial candidate, then try
2860               // to select a better one.
2861               Method = Methods[0];
2862 
2863               // If we find an instance method, emit warning.
2864               if (Method->isInstanceMethod()) {
2865                 if (const ObjCInterfaceDecl *ID =
2866                     dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext())) {
2867                   if (ID->getSuperClass())
2868                     Diag(SelLoc, diag::warn_root_inst_method_not_found)
2869                         << Sel << SourceRange(LBracLoc, RBracLoc);
2870                 }
2871               }
2872 
2873              if (ObjCMethodDecl *BestMethod =
2874                  SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
2875                                   Methods))
2876                Method = BestMethod;
2877             }
2878           }
2879         }
2880       }
2881     } else {
2882       ObjCInterfaceDecl *ClassDecl = nullptr;
2883 
2884       // We allow sending a message to a qualified ID ("id<foo>"), which is ok as
2885       // long as one of the protocols implements the selector (if not, warn).
2886       // And as long as message is not deprecated/unavailable (warn if it is).
2887       if (const ObjCObjectPointerType *QIdTy
2888                                    = ReceiverType->getAsObjCQualifiedIdType()) {
2889         // Search protocols for instance methods.
2890         Method = LookupMethodInQualifiedType(Sel, QIdTy, true);
2891         if (!Method)
2892           Method = LookupMethodInQualifiedType(Sel, QIdTy, false);
2893         if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
2894           return ExprError();
2895       } else if (const ObjCObjectPointerType *OCIType
2896                    = ReceiverType->getAsObjCInterfacePointerType()) {
2897         // We allow sending a message to a pointer to an interface (an object).
2898         ClassDecl = OCIType->getInterfaceDecl();
2899 
2900         // Try to complete the type. Under ARC, this is a hard error from which
2901         // we don't try to recover.
2902         // FIXME: In the non-ARC case, this will still be a hard error if the
2903         // definition is found in a module that's not visible.
2904         const ObjCInterfaceDecl *forwardClass = nullptr;
2905         if (RequireCompleteType(Loc, OCIType->getPointeeType(),
2906               getLangOpts().ObjCAutoRefCount
2907                 ? diag::err_arc_receiver_forward_instance
2908                 : diag::warn_receiver_forward_instance,
2909                                 Receiver? Receiver->getSourceRange()
2910                                         : SourceRange(SuperLoc))) {
2911           if (getLangOpts().ObjCAutoRefCount)
2912             return ExprError();
2913 
2914           forwardClass = OCIType->getInterfaceDecl();
2915           Diag(Receiver ? Receiver->getBeginLoc() : SuperLoc,
2916                diag::note_receiver_is_id);
2917           Method = nullptr;
2918         } else {
2919           Method = ClassDecl->lookupInstanceMethod(Sel);
2920         }
2921 
2922         if (!Method)
2923           // Search protocol qualifiers.
2924           Method = LookupMethodInQualifiedType(Sel, OCIType, true);
2925 
2926         if (!Method) {
2927           // If we have implementations in scope, check "private" methods.
2928           Method = ClassDecl->lookupPrivateMethod(Sel);
2929 
2930           if (!Method && getLangOpts().ObjCAutoRefCount) {
2931             Diag(SelLoc, diag::err_arc_may_not_respond)
2932               << OCIType->getPointeeType() << Sel << RecRange
2933               << SourceRange(SelectorLocs.front(), SelectorLocs.back());
2934             return ExprError();
2935           }
2936 
2937           if (!Method && (!Receiver || !isSelfExpr(Receiver))) {
2938             // If we still haven't found a method, look in the global pool. This
2939             // behavior isn't very desirable, however we need it for GCC
2940             // compatibility. FIXME: should we deviate??
2941             if (OCIType->qual_empty()) {
2942               SmallVector<ObjCMethodDecl*, 4> Methods;
2943               CollectMultipleMethodsInGlobalPool(Sel, Methods,
2944                                                  true/*InstanceFirst*/,
2945                                                  false/*CheckTheOther*/);
2946               if (!Methods.empty()) {
2947                 // We choose the first method as the initial candidate, then try
2948                 // to select a better one.
2949                 Method = Methods[0];
2950 
2951                 if (ObjCMethodDecl *BestMethod =
2952                     SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
2953                                      Methods))
2954                   Method = BestMethod;
2955 
2956                 AreMultipleMethodsInGlobalPool(Sel, Method,
2957                                                SourceRange(LBracLoc, RBracLoc),
2958                                                true/*receiverIdOrClass*/,
2959                                                Methods);
2960               }
2961               if (Method && !forwardClass)
2962                 Diag(SelLoc, diag::warn_maynot_respond)
2963                   << OCIType->getInterfaceDecl()->getIdentifier()
2964                   << Sel << RecRange;
2965             }
2966           }
2967         }
2968         if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs, forwardClass))
2969           return ExprError();
2970       } else {
2971         // Reject other random receiver types (e.g. structs).
2972         Diag(Loc, diag::err_bad_receiver_type)
2973           << ReceiverType << Receiver->getSourceRange();
2974         return ExprError();
2975       }
2976     }
2977   }
2978 
2979   FunctionScopeInfo *DIFunctionScopeInfo =
2980     (Method && Method->getMethodFamily() == OMF_init)
2981       ? getEnclosingFunction() : nullptr;
2982 
2983   if (DIFunctionScopeInfo &&
2984       DIFunctionScopeInfo->ObjCIsDesignatedInit &&
2985       (SuperLoc.isValid() || isSelfExpr(Receiver))) {
2986     bool isDesignatedInitChain = false;
2987     if (SuperLoc.isValid()) {
2988       if (const ObjCObjectPointerType *
2989             OCIType = ReceiverType->getAsObjCInterfacePointerType()) {
2990         if (const ObjCInterfaceDecl *ID = OCIType->getInterfaceDecl()) {
2991           // Either we know this is a designated initializer or we
2992           // conservatively assume it because we don't know for sure.
2993           if (!ID->declaresOrInheritsDesignatedInitializers() ||
2994               ID->isDesignatedInitializer(Sel)) {
2995             isDesignatedInitChain = true;
2996             DIFunctionScopeInfo->ObjCWarnForNoDesignatedInitChain = false;
2997           }
2998         }
2999       }
3000     }
3001     if (!isDesignatedInitChain) {
3002       const ObjCMethodDecl *InitMethod = nullptr;
3003       bool isDesignated =
3004         getCurMethodDecl()->isDesignatedInitializerForTheInterface(&InitMethod);
3005       assert(isDesignated && InitMethod);
3006       (void)isDesignated;
3007       Diag(SelLoc, SuperLoc.isValid() ?
3008              diag::warn_objc_designated_init_non_designated_init_call :
3009              diag::warn_objc_designated_init_non_super_designated_init_call);
3010       Diag(InitMethod->getLocation(),
3011            diag::note_objc_designated_init_marked_here);
3012     }
3013   }
3014 
3015   if (DIFunctionScopeInfo &&
3016       DIFunctionScopeInfo->ObjCIsSecondaryInit &&
3017       (SuperLoc.isValid() || isSelfExpr(Receiver))) {
3018     if (SuperLoc.isValid()) {
3019       Diag(SelLoc, diag::warn_objc_secondary_init_super_init_call);
3020     } else {
3021       DIFunctionScopeInfo->ObjCWarnForNoInitDelegation = false;
3022     }
3023   }
3024 
3025   // Check the message arguments.
3026   unsigned NumArgs = ArgsIn.size();
3027   Expr **Args = ArgsIn.data();
3028   QualType ReturnType;
3029   ExprValueKind VK = VK_RValue;
3030   bool ClassMessage = (ReceiverType->isObjCClassType() ||
3031                        ReceiverType->isObjCQualifiedClassType());
3032   if (CheckMessageArgumentTypes(Receiver, ReceiverType,
3033                                 MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
3034                                 Method, ClassMessage, SuperLoc.isValid(),
3035                                 LBracLoc, RBracLoc, RecRange, ReturnType, VK))
3036     return ExprError();
3037 
3038   if (Method && !Method->getReturnType()->isVoidType() &&
3039       RequireCompleteType(LBracLoc, Method->getReturnType(),
3040                           diag::err_illegal_message_expr_incomplete_type))
3041     return ExprError();
3042 
3043   // In ARC, forbid the user from sending messages to
3044   // retain/release/autorelease/dealloc/retainCount explicitly.
3045   if (getLangOpts().ObjCAutoRefCount) {
3046     ObjCMethodFamily family =
3047       (Method ? Method->getMethodFamily() : Sel.getMethodFamily());
3048     switch (family) {
3049     case OMF_init:
3050       if (Method)
3051         checkInitMethod(Method, ReceiverType);
3052       break;
3053 
3054     case OMF_None:
3055     case OMF_alloc:
3056     case OMF_copy:
3057     case OMF_finalize:
3058     case OMF_mutableCopy:
3059     case OMF_new:
3060     case OMF_self:
3061     case OMF_initialize:
3062       break;
3063 
3064     case OMF_dealloc:
3065     case OMF_retain:
3066     case OMF_release:
3067     case OMF_autorelease:
3068     case OMF_retainCount:
3069       Diag(SelLoc, diag::err_arc_illegal_explicit_message)
3070         << Sel << RecRange;
3071       break;
3072 
3073     case OMF_performSelector:
3074       if (Method && NumArgs >= 1) {
3075         if (const auto *SelExp =
3076                 dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens())) {
3077           Selector ArgSel = SelExp->getSelector();
3078           ObjCMethodDecl *SelMethod =
3079             LookupInstanceMethodInGlobalPool(ArgSel,
3080                                              SelExp->getSourceRange());
3081           if (!SelMethod)
3082             SelMethod =
3083               LookupFactoryMethodInGlobalPool(ArgSel,
3084                                               SelExp->getSourceRange());
3085           if (SelMethod) {
3086             ObjCMethodFamily SelFamily = SelMethod->getMethodFamily();
3087             switch (SelFamily) {
3088               case OMF_alloc:
3089               case OMF_copy:
3090               case OMF_mutableCopy:
3091               case OMF_new:
3092               case OMF_init:
3093                 // Issue error, unless ns_returns_not_retained.
3094                 if (!SelMethod->hasAttr<NSReturnsNotRetainedAttr>()) {
3095                   // selector names a +1 method
3096                   Diag(SelLoc,
3097                        diag::err_arc_perform_selector_retains);
3098                   Diag(SelMethod->getLocation(), diag::note_method_declared_at)
3099                     << SelMethod->getDeclName();
3100                 }
3101                 break;
3102               default:
3103                 // +0 call. OK. unless ns_returns_retained.
3104                 if (SelMethod->hasAttr<NSReturnsRetainedAttr>()) {
3105                   // selector names a +1 method
3106                   Diag(SelLoc,
3107                        diag::err_arc_perform_selector_retains);
3108                   Diag(SelMethod->getLocation(), diag::note_method_declared_at)
3109                     << SelMethod->getDeclName();
3110                 }
3111                 break;
3112             }
3113           }
3114         } else {
3115           // error (may leak).
3116           Diag(SelLoc, diag::warn_arc_perform_selector_leaks);
3117           Diag(Args[0]->getExprLoc(), diag::note_used_here);
3118         }
3119       }
3120       break;
3121     }
3122   }
3123 
3124   DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
3125 
3126   // Construct the appropriate ObjCMessageExpr instance.
3127   ObjCMessageExpr *Result;
3128   if (SuperLoc.isValid())
3129     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
3130                                      SuperLoc,  /*IsInstanceSuper=*/true,
3131                                      ReceiverType, Sel, SelectorLocs, Method,
3132                                      makeArrayRef(Args, NumArgs), RBracLoc,
3133                                      isImplicit);
3134   else {
3135     Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
3136                                      Receiver, Sel, SelectorLocs, Method,
3137                                      makeArrayRef(Args, NumArgs), RBracLoc,
3138                                      isImplicit);
3139     if (!isImplicit)
3140       checkCocoaAPI(*this, Result);
3141   }
3142   if (Method) {
3143     bool IsClassObjectCall = ClassMessage;
3144     // 'self' message receivers in class methods should be treated as message
3145     // sends to the class object in order for the semantic checks to be
3146     // performed correctly. Messages to 'super' already count as class messages,
3147     // so they don't need to be handled here.
3148     if (Receiver && isSelfExpr(Receiver)) {
3149       if (const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
3150         if (OPT->getObjectType()->isObjCClass()) {
3151           if (const auto *CurMeth = getCurMethodDecl()) {
3152             IsClassObjectCall = true;
3153             ReceiverType =
3154                 Context.getObjCInterfaceType(CurMeth->getClassInterface());
3155           }
3156         }
3157       }
3158     }
3159     checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
3160                        ReceiverType, IsClassObjectCall);
3161   }
3162 
3163   if (getLangOpts().ObjCAutoRefCount) {
3164     // In ARC, annotate delegate init calls.
3165     if (Result->getMethodFamily() == OMF_init &&
3166         (SuperLoc.isValid() || isSelfExpr(Receiver))) {
3167       // Only consider init calls *directly* in init implementations,
3168       // not within blocks.
3169       ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(CurContext);
3170       if (method && method->getMethodFamily() == OMF_init) {
3171         // The implicit assignment to self means we also don't want to
3172         // consume the result.
3173         Result->setDelegateInitCall(true);
3174         return Result;
3175       }
3176     }
3177 
3178     // In ARC, check for message sends which are likely to introduce
3179     // retain cycles.
3180     checkRetainCycles(Result);
3181   }
3182 
3183   if (getLangOpts().ObjCWeak) {
3184     if (!isImplicit && Method) {
3185       if (const ObjCPropertyDecl *Prop = Method->findPropertyDecl()) {
3186         bool IsWeak =
3187           Prop->getPropertyAttributes() & ObjCPropertyDecl::OBJC_PR_weak;
3188         if (!IsWeak && Sel.isUnarySelector())
3189           IsWeak = ReturnType.getObjCLifetime() & Qualifiers::OCL_Weak;
3190         if (IsWeak && !isUnevaluatedContext() &&
3191             !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, LBracLoc))
3192           getCurFunction()->recordUseOfWeak(Result, Prop);
3193       }
3194     }
3195   }
3196 
3197   CheckObjCCircularContainer(Result);
3198 
3199   return MaybeBindToTemporary(Result);
3200 }
3201 
3202 static void RemoveSelectorFromWarningCache(Sema &S, Expr* Arg) {
3203   if (ObjCSelectorExpr *OSE =
3204       dyn_cast<ObjCSelectorExpr>(Arg->IgnoreParenCasts())) {
3205     Selector Sel = OSE->getSelector();
3206     SourceLocation Loc = OSE->getAtLoc();
3207     auto Pos = S.ReferencedSelectors.find(Sel);
3208     if (Pos != S.ReferencedSelectors.end() && Pos->second == Loc)
3209       S.ReferencedSelectors.erase(Pos);
3210   }
3211 }
3212 
3213 // ActOnInstanceMessage - used for both unary and keyword messages.
3214 // ArgExprs is optional - if it is present, the number of expressions
3215 // is obtained from Sel.getNumArgs().
3216 ExprResult Sema::ActOnInstanceMessage(Scope *S,
3217                                       Expr *Receiver,
3218                                       Selector Sel,
3219                                       SourceLocation LBracLoc,
3220                                       ArrayRef<SourceLocation> SelectorLocs,
3221                                       SourceLocation RBracLoc,
3222                                       MultiExprArg Args) {
3223   if (!Receiver)
3224     return ExprError();
3225 
3226   // A ParenListExpr can show up while doing error recovery with invalid code.
3227   if (isa<ParenListExpr>(Receiver)) {
3228     ExprResult Result = MaybeConvertParenListExprToParenExpr(S, Receiver);
3229     if (Result.isInvalid()) return ExprError();
3230     Receiver = Result.get();
3231   }
3232 
3233   if (RespondsToSelectorSel.isNull()) {
3234     IdentifierInfo *SelectorId = &Context.Idents.get("respondsToSelector");
3235     RespondsToSelectorSel = Context.Selectors.getUnarySelector(SelectorId);
3236   }
3237   if (Sel == RespondsToSelectorSel)
3238     RemoveSelectorFromWarningCache(*this, Args[0]);
3239 
3240   return BuildInstanceMessage(Receiver, Receiver->getType(),
3241                               /*SuperLoc=*/SourceLocation(), Sel,
3242                               /*Method=*/nullptr, LBracLoc, SelectorLocs,
3243                               RBracLoc, Args);
3244 }
3245 
3246 enum ARCConversionTypeClass {
3247   /// int, void, struct A
3248   ACTC_none,
3249 
3250   /// id, void (^)()
3251   ACTC_retainable,
3252 
3253   /// id*, id***, void (^*)(),
3254   ACTC_indirectRetainable,
3255 
3256   /// void* might be a normal C type, or it might a CF type.
3257   ACTC_voidPtr,
3258 
3259   /// struct A*
3260   ACTC_coreFoundation
3261 };
3262 
3263 static bool isAnyRetainable(ARCConversionTypeClass ACTC) {
3264   return (ACTC == ACTC_retainable ||
3265           ACTC == ACTC_coreFoundation ||
3266           ACTC == ACTC_voidPtr);
3267 }
3268 
3269 static bool isAnyCLike(ARCConversionTypeClass ACTC) {
3270   return ACTC == ACTC_none ||
3271          ACTC == ACTC_voidPtr ||
3272          ACTC == ACTC_coreFoundation;
3273 }
3274 
3275 static ARCConversionTypeClass classifyTypeForARCConversion(QualType type) {
3276   bool isIndirect = false;
3277 
3278   // Ignore an outermost reference type.
3279   if (const ReferenceType *ref = type->getAs<ReferenceType>()) {
3280     type = ref->getPointeeType();
3281     isIndirect = true;
3282   }
3283 
3284   // Drill through pointers and arrays recursively.
3285   while (true) {
3286     if (const PointerType *ptr = type->getAs<PointerType>()) {
3287       type = ptr->getPointeeType();
3288 
3289       // The first level of pointer may be the innermost pointer on a CF type.
3290       if (!isIndirect) {
3291         if (type->isVoidType()) return ACTC_voidPtr;
3292         if (type->isRecordType()) return ACTC_coreFoundation;
3293       }
3294     } else if (const ArrayType *array = type->getAsArrayTypeUnsafe()) {
3295       type = QualType(array->getElementType()->getBaseElementTypeUnsafe(), 0);
3296     } else {
3297       break;
3298     }
3299     isIndirect = true;
3300   }
3301 
3302   if (isIndirect) {
3303     if (type->isObjCARCBridgableType())
3304       return ACTC_indirectRetainable;
3305     return ACTC_none;
3306   }
3307 
3308   if (type->isObjCARCBridgableType())
3309     return ACTC_retainable;
3310 
3311   return ACTC_none;
3312 }
3313 
3314 namespace {
3315   /// A result from the cast checker.
3316   enum ACCResult {
3317     /// Cannot be casted.
3318     ACC_invalid,
3319 
3320     /// Can be safely retained or not retained.
3321     ACC_bottom,
3322 
3323     /// Can be casted at +0.
3324     ACC_plusZero,
3325 
3326     /// Can be casted at +1.
3327     ACC_plusOne
3328   };
3329   ACCResult merge(ACCResult left, ACCResult right) {
3330     if (left == right) return left;
3331     if (left == ACC_bottom) return right;
3332     if (right == ACC_bottom) return left;
3333     return ACC_invalid;
3334   }
3335 
3336   /// A checker which white-lists certain expressions whose conversion
3337   /// to or from retainable type would otherwise be forbidden in ARC.
3338   class ARCCastChecker : public StmtVisitor<ARCCastChecker, ACCResult> {
3339     typedef StmtVisitor<ARCCastChecker, ACCResult> super;
3340 
3341     ASTContext &Context;
3342     ARCConversionTypeClass SourceClass;
3343     ARCConversionTypeClass TargetClass;
3344     bool Diagnose;
3345 
3346     static bool isCFType(QualType type) {
3347       // Someday this can use ns_bridged.  For now, it has to do this.
3348       return type->isCARCBridgableType();
3349     }
3350 
3351   public:
3352     ARCCastChecker(ASTContext &Context, ARCConversionTypeClass source,
3353                    ARCConversionTypeClass target, bool diagnose)
3354       : Context(Context), SourceClass(source), TargetClass(target),
3355         Diagnose(diagnose) {}
3356 
3357     using super::Visit;
3358     ACCResult Visit(Expr *e) {
3359       return super::Visit(e->IgnoreParens());
3360     }
3361 
3362     ACCResult VisitStmt(Stmt *s) {
3363       return ACC_invalid;
3364     }
3365 
3366     /// Null pointer constants can be casted however you please.
3367     ACCResult VisitExpr(Expr *e) {
3368       if (e->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
3369         return ACC_bottom;
3370       return ACC_invalid;
3371     }
3372 
3373     /// Objective-C string literals can be safely casted.
3374     ACCResult VisitObjCStringLiteral(ObjCStringLiteral *e) {
3375       // If we're casting to any retainable type, go ahead.  Global
3376       // strings are immune to retains, so this is bottom.
3377       if (isAnyRetainable(TargetClass)) return ACC_bottom;
3378 
3379       return ACC_invalid;
3380     }
3381 
3382     /// Look through certain implicit and explicit casts.
3383     ACCResult VisitCastExpr(CastExpr *e) {
3384       switch (e->getCastKind()) {
3385         case CK_NullToPointer:
3386           return ACC_bottom;
3387 
3388         case CK_NoOp:
3389         case CK_LValueToRValue:
3390         case CK_BitCast:
3391         case CK_CPointerToObjCPointerCast:
3392         case CK_BlockPointerToObjCPointerCast:
3393         case CK_AnyPointerToBlockPointerCast:
3394           return Visit(e->getSubExpr());
3395 
3396         default:
3397           return ACC_invalid;
3398       }
3399     }
3400 
3401     /// Look through unary extension.
3402     ACCResult VisitUnaryExtension(UnaryOperator *e) {
3403       return Visit(e->getSubExpr());
3404     }
3405 
3406     /// Ignore the LHS of a comma operator.
3407     ACCResult VisitBinComma(BinaryOperator *e) {
3408       return Visit(e->getRHS());
3409     }
3410 
3411     /// Conditional operators are okay if both sides are okay.
3412     ACCResult VisitConditionalOperator(ConditionalOperator *e) {
3413       ACCResult left = Visit(e->getTrueExpr());
3414       if (left == ACC_invalid) return ACC_invalid;
3415       return merge(left, Visit(e->getFalseExpr()));
3416     }
3417 
3418     /// Look through pseudo-objects.
3419     ACCResult VisitPseudoObjectExpr(PseudoObjectExpr *e) {
3420       // If we're getting here, we should always have a result.
3421       return Visit(e->getResultExpr());
3422     }
3423 
3424     /// Statement expressions are okay if their result expression is okay.
3425     ACCResult VisitStmtExpr(StmtExpr *e) {
3426       return Visit(e->getSubStmt()->body_back());
3427     }
3428 
3429     /// Some declaration references are okay.
3430     ACCResult VisitDeclRefExpr(DeclRefExpr *e) {
3431       VarDecl *var = dyn_cast<VarDecl>(e->getDecl());
3432       // References to global constants are okay.
3433       if (isAnyRetainable(TargetClass) &&
3434           isAnyRetainable(SourceClass) &&
3435           var &&
3436           !var->hasDefinition(Context) &&
3437           var->getType().isConstQualified()) {
3438 
3439         // In system headers, they can also be assumed to be immune to retains.
3440         // These are things like 'kCFStringTransformToLatin'.
3441         if (Context.getSourceManager().isInSystemHeader(var->getLocation()))
3442           return ACC_bottom;
3443 
3444         return ACC_plusZero;
3445       }
3446 
3447       // Nothing else.
3448       return ACC_invalid;
3449     }
3450 
3451     /// Some calls are okay.
3452     ACCResult VisitCallExpr(CallExpr *e) {
3453       if (FunctionDecl *fn = e->getDirectCallee())
3454         if (ACCResult result = checkCallToFunction(fn))
3455           return result;
3456 
3457       return super::VisitCallExpr(e);
3458     }
3459 
3460     ACCResult checkCallToFunction(FunctionDecl *fn) {
3461       // Require a CF*Ref return type.
3462       if (!isCFType(fn->getReturnType()))
3463         return ACC_invalid;
3464 
3465       if (!isAnyRetainable(TargetClass))
3466         return ACC_invalid;
3467 
3468       // Honor an explicit 'not retained' attribute.
3469       if (fn->hasAttr<CFReturnsNotRetainedAttr>())
3470         return ACC_plusZero;
3471 
3472       // Honor an explicit 'retained' attribute, except that for
3473       // now we're not going to permit implicit handling of +1 results,
3474       // because it's a bit frightening.
3475       if (fn->hasAttr<CFReturnsRetainedAttr>())
3476         return Diagnose ? ACC_plusOne
3477                         : ACC_invalid; // ACC_plusOne if we start accepting this
3478 
3479       // Recognize this specific builtin function, which is used by CFSTR.
3480       unsigned builtinID = fn->getBuiltinID();
3481       if (builtinID == Builtin::BI__builtin___CFStringMakeConstantString)
3482         return ACC_bottom;
3483 
3484       // Otherwise, don't do anything implicit with an unaudited function.
3485       if (!fn->hasAttr<CFAuditedTransferAttr>())
3486         return ACC_invalid;
3487 
3488       // Otherwise, it's +0 unless it follows the create convention.
3489       if (ento::coreFoundation::followsCreateRule(fn))
3490         return Diagnose ? ACC_plusOne
3491                         : ACC_invalid; // ACC_plusOne if we start accepting this
3492 
3493       return ACC_plusZero;
3494     }
3495 
3496     ACCResult VisitObjCMessageExpr(ObjCMessageExpr *e) {
3497       return checkCallToMethod(e->getMethodDecl());
3498     }
3499 
3500     ACCResult VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *e) {
3501       ObjCMethodDecl *method;
3502       if (e->isExplicitProperty())
3503         method = e->getExplicitProperty()->getGetterMethodDecl();
3504       else
3505         method = e->getImplicitPropertyGetter();
3506       return checkCallToMethod(method);
3507     }
3508 
3509     ACCResult checkCallToMethod(ObjCMethodDecl *method) {
3510       if (!method) return ACC_invalid;
3511 
3512       // Check for message sends to functions returning CF types.  We
3513       // just obey the Cocoa conventions with these, even though the
3514       // return type is CF.
3515       if (!isAnyRetainable(TargetClass) || !isCFType(method->getReturnType()))
3516         return ACC_invalid;
3517 
3518       // If the method is explicitly marked not-retained, it's +0.
3519       if (method->hasAttr<CFReturnsNotRetainedAttr>())
3520         return ACC_plusZero;
3521 
3522       // If the method is explicitly marked as returning retained, or its
3523       // selector follows a +1 Cocoa convention, treat it as +1.
3524       if (method->hasAttr<CFReturnsRetainedAttr>())
3525         return ACC_plusOne;
3526 
3527       switch (method->getSelector().getMethodFamily()) {
3528       case OMF_alloc:
3529       case OMF_copy:
3530       case OMF_mutableCopy:
3531       case OMF_new:
3532         return ACC_plusOne;
3533 
3534       default:
3535         // Otherwise, treat it as +0.
3536         return ACC_plusZero;
3537       }
3538     }
3539   };
3540 } // end anonymous namespace
3541 
3542 bool Sema::isKnownName(StringRef name) {
3543   if (name.empty())
3544     return false;
3545   LookupResult R(*this, &Context.Idents.get(name), SourceLocation(),
3546                  Sema::LookupOrdinaryName);
3547   return LookupName(R, TUScope, false);
3548 }
3549 
3550 static void addFixitForObjCARCConversion(Sema &S,
3551                                          DiagnosticBuilder &DiagB,
3552                                          Sema::CheckedConversionKind CCK,
3553                                          SourceLocation afterLParen,
3554                                          QualType castType,
3555                                          Expr *castExpr,
3556                                          Expr *realCast,
3557                                          const char *bridgeKeyword,
3558                                          const char *CFBridgeName) {
3559   // We handle C-style and implicit casts here.
3560   switch (CCK) {
3561   case Sema::CCK_ImplicitConversion:
3562   case Sema::CCK_ForBuiltinOverloadedOp:
3563   case Sema::CCK_CStyleCast:
3564   case Sema::CCK_OtherCast:
3565     break;
3566   case Sema::CCK_FunctionalCast:
3567     return;
3568   }
3569 
3570   if (CFBridgeName) {
3571     if (CCK == Sema::CCK_OtherCast) {
3572       if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
3573         SourceRange range(NCE->getOperatorLoc(),
3574                           NCE->getAngleBrackets().getEnd());
3575         SmallString<32> BridgeCall;
3576 
3577         SourceManager &SM = S.getSourceManager();
3578         char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
3579         if (Lexer::isIdentifierBodyChar(PrevChar, S.getLangOpts()))
3580           BridgeCall += ' ';
3581 
3582         BridgeCall += CFBridgeName;
3583         DiagB.AddFixItHint(FixItHint::CreateReplacement(range, BridgeCall));
3584       }
3585       return;
3586     }
3587     Expr *castedE = castExpr;
3588     if (CStyleCastExpr *CCE = dyn_cast<CStyleCastExpr>(castedE))
3589       castedE = CCE->getSubExpr();
3590     castedE = castedE->IgnoreImpCasts();
3591     SourceRange range = castedE->getSourceRange();
3592 
3593     SmallString<32> BridgeCall;
3594 
3595     SourceManager &SM = S.getSourceManager();
3596     char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
3597     if (Lexer::isIdentifierBodyChar(PrevChar, S.getLangOpts()))
3598       BridgeCall += ' ';
3599 
3600     BridgeCall += CFBridgeName;
3601 
3602     if (isa<ParenExpr>(castedE)) {
3603       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3604                          BridgeCall));
3605     } else {
3606       BridgeCall += '(';
3607       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3608                                                     BridgeCall));
3609       DiagB.AddFixItHint(FixItHint::CreateInsertion(
3610                                        S.getLocForEndOfToken(range.getEnd()),
3611                                        ")"));
3612     }
3613     return;
3614   }
3615 
3616   if (CCK == Sema::CCK_CStyleCast) {
3617     DiagB.AddFixItHint(FixItHint::CreateInsertion(afterLParen, bridgeKeyword));
3618   } else if (CCK == Sema::CCK_OtherCast) {
3619     if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
3620       std::string castCode = "(";
3621       castCode += bridgeKeyword;
3622       castCode += castType.getAsString();
3623       castCode += ")";
3624       SourceRange Range(NCE->getOperatorLoc(),
3625                         NCE->getAngleBrackets().getEnd());
3626       DiagB.AddFixItHint(FixItHint::CreateReplacement(Range, castCode));
3627     }
3628   } else {
3629     std::string castCode = "(";
3630     castCode += bridgeKeyword;
3631     castCode += castType.getAsString();
3632     castCode += ")";
3633     Expr *castedE = castExpr->IgnoreImpCasts();
3634     SourceRange range = castedE->getSourceRange();
3635     if (isa<ParenExpr>(castedE)) {
3636       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3637                          castCode));
3638     } else {
3639       castCode += "(";
3640       DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
3641                                                     castCode));
3642       DiagB.AddFixItHint(FixItHint::CreateInsertion(
3643                                        S.getLocForEndOfToken(range.getEnd()),
3644                                        ")"));
3645     }
3646   }
3647 }
3648 
3649 template <typename T>
3650 static inline T *getObjCBridgeAttr(const TypedefType *TD) {
3651   TypedefNameDecl *TDNDecl = TD->getDecl();
3652   QualType QT = TDNDecl->getUnderlyingType();
3653   if (QT->isPointerType()) {
3654     QT = QT->getPointeeType();
3655     if (const RecordType *RT = QT->getAs<RecordType>())
3656       if (RecordDecl *RD = RT->getDecl()->getMostRecentDecl())
3657         return RD->getAttr<T>();
3658   }
3659   return nullptr;
3660 }
3661 
3662 static ObjCBridgeRelatedAttr *ObjCBridgeRelatedAttrFromType(QualType T,
3663                                                             TypedefNameDecl *&TDNDecl) {
3664   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
3665     TDNDecl = TD->getDecl();
3666     if (ObjCBridgeRelatedAttr *ObjCBAttr =
3667         getObjCBridgeAttr<ObjCBridgeRelatedAttr>(TD))
3668       return ObjCBAttr;
3669     T = TDNDecl->getUnderlyingType();
3670   }
3671   return nullptr;
3672 }
3673 
3674 static void
3675 diagnoseObjCARCConversion(Sema &S, SourceRange castRange,
3676                           QualType castType, ARCConversionTypeClass castACTC,
3677                           Expr *castExpr, Expr *realCast,
3678                           ARCConversionTypeClass exprACTC,
3679                           Sema::CheckedConversionKind CCK) {
3680   SourceLocation loc =
3681     (castRange.isValid() ? castRange.getBegin() : castExpr->getExprLoc());
3682 
3683   if (S.makeUnavailableInSystemHeader(loc,
3684                                  UnavailableAttr::IR_ARCForbiddenConversion))
3685     return;
3686 
3687   QualType castExprType = castExpr->getType();
3688   // Defer emitting a diagnostic for bridge-related casts; that will be
3689   // handled by CheckObjCBridgeRelatedConversions.
3690   TypedefNameDecl *TDNDecl = nullptr;
3691   if ((castACTC == ACTC_coreFoundation &&  exprACTC == ACTC_retainable &&
3692        ObjCBridgeRelatedAttrFromType(castType, TDNDecl)) ||
3693       (exprACTC == ACTC_coreFoundation && castACTC == ACTC_retainable &&
3694        ObjCBridgeRelatedAttrFromType(castExprType, TDNDecl)))
3695     return;
3696 
3697   unsigned srcKind = 0;
3698   switch (exprACTC) {
3699   case ACTC_none:
3700   case ACTC_coreFoundation:
3701   case ACTC_voidPtr:
3702     srcKind = (castExprType->isPointerType() ? 1 : 0);
3703     break;
3704   case ACTC_retainable:
3705     srcKind = (castExprType->isBlockPointerType() ? 2 : 3);
3706     break;
3707   case ACTC_indirectRetainable:
3708     srcKind = 4;
3709     break;
3710   }
3711 
3712   // Check whether this could be fixed with a bridge cast.
3713   SourceLocation afterLParen = S.getLocForEndOfToken(castRange.getBegin());
3714   SourceLocation noteLoc = afterLParen.isValid() ? afterLParen : loc;
3715 
3716   unsigned convKindForDiag = Sema::isCast(CCK) ? 0 : 1;
3717 
3718   // Bridge from an ARC type to a CF type.
3719   if (castACTC == ACTC_retainable && isAnyRetainable(exprACTC)) {
3720 
3721     S.Diag(loc, diag::err_arc_cast_requires_bridge)
3722       << convKindForDiag
3723       << 2 // of C pointer type
3724       << castExprType
3725       << unsigned(castType->isBlockPointerType()) // to ObjC|block type
3726       << castType
3727       << castRange
3728       << castExpr->getSourceRange();
3729     bool br = S.isKnownName("CFBridgingRelease");
3730     ACCResult CreateRule =
3731       ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
3732     assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
3733     if (CreateRule != ACC_plusOne)
3734     {
3735       DiagnosticBuilder DiagB =
3736         (CCK != Sema::CCK_OtherCast) ? S.Diag(noteLoc, diag::note_arc_bridge)
3737                               : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
3738 
3739       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3740                                    castType, castExpr, realCast, "__bridge ",
3741                                    nullptr);
3742     }
3743     if (CreateRule != ACC_plusZero)
3744     {
3745       DiagnosticBuilder DiagB =
3746         (CCK == Sema::CCK_OtherCast && !br) ?
3747           S.Diag(noteLoc, diag::note_arc_cstyle_bridge_transfer) << castExprType :
3748           S.Diag(br ? castExpr->getExprLoc() : noteLoc,
3749                  diag::note_arc_bridge_transfer)
3750             << castExprType << br;
3751 
3752       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3753                                    castType, castExpr, realCast, "__bridge_transfer ",
3754                                    br ? "CFBridgingRelease" : nullptr);
3755     }
3756 
3757     return;
3758   }
3759 
3760   // Bridge from a CF type to an ARC type.
3761   if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC)) {
3762     bool br = S.isKnownName("CFBridgingRetain");
3763     S.Diag(loc, diag::err_arc_cast_requires_bridge)
3764       << convKindForDiag
3765       << unsigned(castExprType->isBlockPointerType()) // of ObjC|block type
3766       << castExprType
3767       << 2 // to C pointer type
3768       << castType
3769       << castRange
3770       << castExpr->getSourceRange();
3771     ACCResult CreateRule =
3772       ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
3773     assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
3774     if (CreateRule != ACC_plusOne)
3775     {
3776       DiagnosticBuilder DiagB =
3777       (CCK != Sema::CCK_OtherCast) ? S.Diag(noteLoc, diag::note_arc_bridge)
3778                                : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
3779       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3780                                    castType, castExpr, realCast, "__bridge ",
3781                                    nullptr);
3782     }
3783     if (CreateRule != ACC_plusZero)
3784     {
3785       DiagnosticBuilder DiagB =
3786         (CCK == Sema::CCK_OtherCast && !br) ?
3787           S.Diag(noteLoc, diag::note_arc_cstyle_bridge_retained) << castType :
3788           S.Diag(br ? castExpr->getExprLoc() : noteLoc,
3789                  diag::note_arc_bridge_retained)
3790             << castType << br;
3791 
3792       addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
3793                                    castType, castExpr, realCast, "__bridge_retained ",
3794                                    br ? "CFBridgingRetain" : nullptr);
3795     }
3796 
3797     return;
3798   }
3799 
3800   S.Diag(loc, diag::err_arc_mismatched_cast)
3801     << !convKindForDiag
3802     << srcKind << castExprType << castType
3803     << castRange << castExpr->getSourceRange();
3804 }
3805 
3806 template <typename TB>
3807 static bool CheckObjCBridgeNSCast(Sema &S, QualType castType, Expr *castExpr,
3808                                   bool &HadTheAttribute, bool warn) {
3809   QualType T = castExpr->getType();
3810   HadTheAttribute = false;
3811   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
3812     TypedefNameDecl *TDNDecl = TD->getDecl();
3813     if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
3814       if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
3815         HadTheAttribute = true;
3816         if (Parm->isStr("id"))
3817           return true;
3818 
3819         NamedDecl *Target = nullptr;
3820         // Check for an existing type with this name.
3821         LookupResult R(S, DeclarationName(Parm), SourceLocation(),
3822                        Sema::LookupOrdinaryName);
3823         if (S.LookupName(R, S.TUScope)) {
3824           Target = R.getFoundDecl();
3825           if (Target && isa<ObjCInterfaceDecl>(Target)) {
3826             ObjCInterfaceDecl *ExprClass = cast<ObjCInterfaceDecl>(Target);
3827             if (const ObjCObjectPointerType *InterfacePointerType =
3828                   castType->getAsObjCInterfacePointerType()) {
3829               ObjCInterfaceDecl *CastClass
3830                 = InterfacePointerType->getObjectType()->getInterface();
3831               if ((CastClass == ExprClass) ||
3832                   (CastClass && CastClass->isSuperClassOf(ExprClass)))
3833                 return true;
3834               if (warn)
3835                 S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
3836                     << T << Target->getName() << castType->getPointeeType();
3837               return false;
3838             } else if (castType->isObjCIdType() ||
3839                        (S.Context.ObjCObjectAdoptsQTypeProtocols(
3840                           castType, ExprClass)))
3841               // ok to cast to 'id'.
3842               // casting to id<p-list> is ok if bridge type adopts all of
3843               // p-list protocols.
3844               return true;
3845             else {
3846               if (warn) {
3847                 S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
3848                     << T << Target->getName() << castType;
3849                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
3850                 S.Diag(Target->getBeginLoc(), diag::note_declared_at);
3851               }
3852               return false;
3853            }
3854           }
3855         } else if (!castType->isObjCIdType()) {
3856           S.Diag(castExpr->getBeginLoc(),
3857                  diag::err_objc_cf_bridged_not_interface)
3858               << castExpr->getType() << Parm;
3859           S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
3860           if (Target)
3861             S.Diag(Target->getBeginLoc(), diag::note_declared_at);
3862         }
3863         return true;
3864       }
3865       return false;
3866     }
3867     T = TDNDecl->getUnderlyingType();
3868   }
3869   return true;
3870 }
3871 
3872 template <typename TB>
3873 static bool CheckObjCBridgeCFCast(Sema &S, QualType castType, Expr *castExpr,
3874                                   bool &HadTheAttribute, bool warn) {
3875   QualType T = castType;
3876   HadTheAttribute = false;
3877   while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
3878     TypedefNameDecl *TDNDecl = TD->getDecl();
3879     if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
3880       if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
3881         HadTheAttribute = true;
3882         if (Parm->isStr("id"))
3883           return true;
3884 
3885         NamedDecl *Target = nullptr;
3886         // Check for an existing type with this name.
3887         LookupResult R(S, DeclarationName(Parm), SourceLocation(),
3888                        Sema::LookupOrdinaryName);
3889         if (S.LookupName(R, S.TUScope)) {
3890           Target = R.getFoundDecl();
3891           if (Target && isa<ObjCInterfaceDecl>(Target)) {
3892             ObjCInterfaceDecl *CastClass = cast<ObjCInterfaceDecl>(Target);
3893             if (const ObjCObjectPointerType *InterfacePointerType =
3894                   castExpr->getType()->getAsObjCInterfacePointerType()) {
3895               ObjCInterfaceDecl *ExprClass
3896                 = InterfacePointerType->getObjectType()->getInterface();
3897               if ((CastClass == ExprClass) ||
3898                   (ExprClass && CastClass->isSuperClassOf(ExprClass)))
3899                 return true;
3900               if (warn) {
3901                 S.Diag(castExpr->getBeginLoc(),
3902                        diag::warn_objc_invalid_bridge_to_cf)
3903                     << castExpr->getType()->getPointeeType() << T;
3904                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
3905               }
3906               return false;
3907             } else if (castExpr->getType()->isObjCIdType() ||
3908                        (S.Context.QIdProtocolsAdoptObjCObjectProtocols(
3909                           castExpr->getType(), CastClass)))
3910               // ok to cast an 'id' expression to a CFtype.
3911               // ok to cast an 'id<plist>' expression to CFtype provided plist
3912               // adopts all of CFtype's ObjetiveC's class plist.
3913               return true;
3914             else {
3915               if (warn) {
3916                 S.Diag(castExpr->getBeginLoc(),
3917                        diag::warn_objc_invalid_bridge_to_cf)
3918                     << castExpr->getType() << castType;
3919                 S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
3920                 S.Diag(Target->getBeginLoc(), diag::note_declared_at);
3921               }
3922               return false;
3923             }
3924           }
3925         }
3926         S.Diag(castExpr->getBeginLoc(),
3927                diag::err_objc_ns_bridged_invalid_cfobject)
3928             << castExpr->getType() << castType;
3929         S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
3930         if (Target)
3931           S.Diag(Target->getBeginLoc(), diag::note_declared_at);
3932         return true;
3933       }
3934       return false;
3935     }
3936     T = TDNDecl->getUnderlyingType();
3937   }
3938   return true;
3939 }
3940 
3941 void Sema::CheckTollFreeBridgeCast(QualType castType, Expr *castExpr) {
3942   if (!getLangOpts().ObjC)
3943     return;
3944   // warn in presence of __bridge casting to or from a toll free bridge cast.
3945   ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExpr->getType());
3946   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
3947   if (castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) {
3948     bool HasObjCBridgeAttr;
3949     bool ObjCBridgeAttrWillNotWarn =
3950       CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
3951                                             false);
3952     if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
3953       return;
3954     bool HasObjCBridgeMutableAttr;
3955     bool ObjCBridgeMutableAttrWillNotWarn =
3956       CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
3957                                                    HasObjCBridgeMutableAttr, false);
3958     if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
3959       return;
3960 
3961     if (HasObjCBridgeAttr)
3962       CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
3963                                             true);
3964     else if (HasObjCBridgeMutableAttr)
3965       CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
3966                                                    HasObjCBridgeMutableAttr, true);
3967   }
3968   else if (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable) {
3969     bool HasObjCBridgeAttr;
3970     bool ObjCBridgeAttrWillNotWarn =
3971       CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
3972                                             false);
3973     if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
3974       return;
3975     bool HasObjCBridgeMutableAttr;
3976     bool ObjCBridgeMutableAttrWillNotWarn =
3977       CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
3978                                                    HasObjCBridgeMutableAttr, false);
3979     if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
3980       return;
3981 
3982     if (HasObjCBridgeAttr)
3983       CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
3984                                             true);
3985     else if (HasObjCBridgeMutableAttr)
3986       CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
3987                                                    HasObjCBridgeMutableAttr, true);
3988   }
3989 }
3990 
3991 void Sema::CheckObjCBridgeRelatedCast(QualType castType, Expr *castExpr) {
3992   QualType SrcType = castExpr->getType();
3993   if (ObjCPropertyRefExpr *PRE = dyn_cast<ObjCPropertyRefExpr>(castExpr)) {
3994     if (PRE->isExplicitProperty()) {
3995       if (ObjCPropertyDecl *PDecl = PRE->getExplicitProperty())
3996         SrcType = PDecl->getType();
3997     }
3998     else if (PRE->isImplicitProperty()) {
3999       if (ObjCMethodDecl *Getter = PRE->getImplicitPropertyGetter())
4000         SrcType = Getter->getReturnType();
4001     }
4002   }
4003 
4004   ARCConversionTypeClass srcExprACTC = classifyTypeForARCConversion(SrcType);
4005   ARCConversionTypeClass castExprACTC = classifyTypeForARCConversion(castType);
4006   if (srcExprACTC != ACTC_retainable || castExprACTC != ACTC_coreFoundation)
4007     return;
4008   CheckObjCBridgeRelatedConversions(castExpr->getBeginLoc(), castType, SrcType,
4009                                     castExpr);
4010 }
4011 
4012 bool Sema::CheckTollFreeBridgeStaticCast(QualType castType, Expr *castExpr,
4013                                          CastKind &Kind) {
4014   if (!getLangOpts().ObjC)
4015     return false;
4016   ARCConversionTypeClass exprACTC =
4017     classifyTypeForARCConversion(castExpr->getType());
4018   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
4019   if ((castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) ||
4020       (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable)) {
4021     CheckTollFreeBridgeCast(castType, castExpr);
4022     Kind = (castACTC == ACTC_coreFoundation) ? CK_BitCast
4023                                              : CK_CPointerToObjCPointerCast;
4024     return true;
4025   }
4026   return false;
4027 }
4028 
4029 bool Sema::checkObjCBridgeRelatedComponents(SourceLocation Loc,
4030                                             QualType DestType, QualType SrcType,
4031                                             ObjCInterfaceDecl *&RelatedClass,
4032                                             ObjCMethodDecl *&ClassMethod,
4033                                             ObjCMethodDecl *&InstanceMethod,
4034                                             TypedefNameDecl *&TDNDecl,
4035                                             bool CfToNs, bool Diagnose) {
4036   QualType T = CfToNs ? SrcType : DestType;
4037   ObjCBridgeRelatedAttr *ObjCBAttr = ObjCBridgeRelatedAttrFromType(T, TDNDecl);
4038   if (!ObjCBAttr)
4039     return false;
4040 
4041   IdentifierInfo *RCId = ObjCBAttr->getRelatedClass();
4042   IdentifierInfo *CMId = ObjCBAttr->getClassMethod();
4043   IdentifierInfo *IMId = ObjCBAttr->getInstanceMethod();
4044   if (!RCId)
4045     return false;
4046   NamedDecl *Target = nullptr;
4047   // Check for an existing type with this name.
4048   LookupResult R(*this, DeclarationName(RCId), SourceLocation(),
4049                  Sema::LookupOrdinaryName);
4050   if (!LookupName(R, TUScope)) {
4051     if (Diagnose) {
4052       Diag(Loc, diag::err_objc_bridged_related_invalid_class) << RCId
4053             << SrcType << DestType;
4054       Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4055     }
4056     return false;
4057   }
4058   Target = R.getFoundDecl();
4059   if (Target && isa<ObjCInterfaceDecl>(Target))
4060     RelatedClass = cast<ObjCInterfaceDecl>(Target);
4061   else {
4062     if (Diagnose) {
4063       Diag(Loc, diag::err_objc_bridged_related_invalid_class_name) << RCId
4064             << SrcType << DestType;
4065       Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4066       if (Target)
4067         Diag(Target->getBeginLoc(), diag::note_declared_at);
4068     }
4069     return false;
4070   }
4071 
4072   // Check for an existing class method with the given selector name.
4073   if (CfToNs && CMId) {
4074     Selector Sel = Context.Selectors.getUnarySelector(CMId);
4075     ClassMethod = RelatedClass->lookupMethod(Sel, false);
4076     if (!ClassMethod) {
4077       if (Diagnose) {
4078         Diag(Loc, diag::err_objc_bridged_related_known_method)
4079               << SrcType << DestType << Sel << false;
4080         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4081       }
4082       return false;
4083     }
4084   }
4085 
4086   // Check for an existing instance method with the given selector name.
4087   if (!CfToNs && IMId) {
4088     Selector Sel = Context.Selectors.getNullarySelector(IMId);
4089     InstanceMethod = RelatedClass->lookupMethod(Sel, true);
4090     if (!InstanceMethod) {
4091       if (Diagnose) {
4092         Diag(Loc, diag::err_objc_bridged_related_known_method)
4093               << SrcType << DestType << Sel << true;
4094         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4095       }
4096       return false;
4097     }
4098   }
4099   return true;
4100 }
4101 
4102 bool
4103 Sema::CheckObjCBridgeRelatedConversions(SourceLocation Loc,
4104                                         QualType DestType, QualType SrcType,
4105                                         Expr *&SrcExpr, bool Diagnose) {
4106   ARCConversionTypeClass rhsExprACTC = classifyTypeForARCConversion(SrcType);
4107   ARCConversionTypeClass lhsExprACTC = classifyTypeForARCConversion(DestType);
4108   bool CfToNs = (rhsExprACTC == ACTC_coreFoundation && lhsExprACTC == ACTC_retainable);
4109   bool NsToCf = (rhsExprACTC == ACTC_retainable && lhsExprACTC == ACTC_coreFoundation);
4110   if (!CfToNs && !NsToCf)
4111     return false;
4112 
4113   ObjCInterfaceDecl *RelatedClass;
4114   ObjCMethodDecl *ClassMethod = nullptr;
4115   ObjCMethodDecl *InstanceMethod = nullptr;
4116   TypedefNameDecl *TDNDecl = nullptr;
4117   if (!checkObjCBridgeRelatedComponents(Loc, DestType, SrcType, RelatedClass,
4118                                         ClassMethod, InstanceMethod, TDNDecl,
4119                                         CfToNs, Diagnose))
4120     return false;
4121 
4122   if (CfToNs) {
4123     // Implicit conversion from CF to ObjC object is needed.
4124     if (ClassMethod) {
4125       if (Diagnose) {
4126         std::string ExpressionString = "[";
4127         ExpressionString += RelatedClass->getNameAsString();
4128         ExpressionString += " ";
4129         ExpressionString += ClassMethod->getSelector().getAsString();
4130         SourceLocation SrcExprEndLoc =
4131             getLocForEndOfToken(SrcExpr->getEndLoc());
4132         // Provide a fixit: [RelatedClass ClassMethod SrcExpr]
4133         Diag(Loc, diag::err_objc_bridged_related_known_method)
4134             << SrcType << DestType << ClassMethod->getSelector() << false
4135             << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(),
4136                                           ExpressionString)
4137             << FixItHint::CreateInsertion(SrcExprEndLoc, "]");
4138         Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
4139         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4140 
4141         QualType receiverType = Context.getObjCInterfaceType(RelatedClass);
4142         // Argument.
4143         Expr *args[] = { SrcExpr };
4144         ExprResult msg = BuildClassMessageImplicit(receiverType, false,
4145                                       ClassMethod->getLocation(),
4146                                       ClassMethod->getSelector(), ClassMethod,
4147                                       MultiExprArg(args, 1));
4148         SrcExpr = msg.get();
4149       }
4150       return true;
4151     }
4152   }
4153   else {
4154     // Implicit conversion from ObjC type to CF object is needed.
4155     if (InstanceMethod) {
4156       if (Diagnose) {
4157         std::string ExpressionString;
4158         SourceLocation SrcExprEndLoc =
4159             getLocForEndOfToken(SrcExpr->getEndLoc());
4160         if (InstanceMethod->isPropertyAccessor())
4161           if (const ObjCPropertyDecl *PDecl =
4162                   InstanceMethod->findPropertyDecl()) {
4163             // fixit: ObjectExpr.propertyname when it is  aproperty accessor.
4164             ExpressionString = ".";
4165             ExpressionString += PDecl->getNameAsString();
4166             Diag(Loc, diag::err_objc_bridged_related_known_method)
4167                 << SrcType << DestType << InstanceMethod->getSelector() << true
4168                 << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
4169           }
4170         if (ExpressionString.empty()) {
4171           // Provide a fixit: [ObjectExpr InstanceMethod]
4172           ExpressionString = " ";
4173           ExpressionString += InstanceMethod->getSelector().getAsString();
4174           ExpressionString += "]";
4175 
4176           Diag(Loc, diag::err_objc_bridged_related_known_method)
4177               << SrcType << DestType << InstanceMethod->getSelector() << true
4178               << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(), "[")
4179               << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
4180         }
4181         Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
4182         Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
4183 
4184         ExprResult msg =
4185           BuildInstanceMessageImplicit(SrcExpr, SrcType,
4186                                        InstanceMethod->getLocation(),
4187                                        InstanceMethod->getSelector(),
4188                                        InstanceMethod, None);
4189         SrcExpr = msg.get();
4190       }
4191       return true;
4192     }
4193   }
4194   return false;
4195 }
4196 
4197 Sema::ARCConversionResult
4198 Sema::CheckObjCConversion(SourceRange castRange, QualType castType,
4199                           Expr *&castExpr, CheckedConversionKind CCK,
4200                           bool Diagnose, bool DiagnoseCFAudited,
4201                           BinaryOperatorKind Opc) {
4202   QualType castExprType = castExpr->getType();
4203 
4204   // For the purposes of the classification, we assume reference types
4205   // will bind to temporaries.
4206   QualType effCastType = castType;
4207   if (const ReferenceType *ref = castType->getAs<ReferenceType>())
4208     effCastType = ref->getPointeeType();
4209 
4210   ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExprType);
4211   ARCConversionTypeClass castACTC = classifyTypeForARCConversion(effCastType);
4212   if (exprACTC == castACTC) {
4213     // Check for viability and report error if casting an rvalue to a
4214     // life-time qualifier.
4215     if (castACTC == ACTC_retainable &&
4216         (CCK == CCK_CStyleCast || CCK == CCK_OtherCast) &&
4217         castType != castExprType) {
4218       const Type *DT = castType.getTypePtr();
4219       QualType QDT = castType;
4220       // We desugar some types but not others. We ignore those
4221       // that cannot happen in a cast; i.e. auto, and those which
4222       // should not be de-sugared; i.e typedef.
4223       if (const ParenType *PT = dyn_cast<ParenType>(DT))
4224         QDT = PT->desugar();
4225       else if (const TypeOfType *TP = dyn_cast<TypeOfType>(DT))
4226         QDT = TP->desugar();
4227       else if (const AttributedType *AT = dyn_cast<AttributedType>(DT))
4228         QDT = AT->desugar();
4229       if (QDT != castType &&
4230           QDT.getObjCLifetime() !=  Qualifiers::OCL_None) {
4231         if (Diagnose) {
4232           SourceLocation loc = (castRange.isValid() ? castRange.getBegin()
4233                                                     : castExpr->getExprLoc());
4234           Diag(loc, diag::err_arc_nolifetime_behavior);
4235         }
4236         return ACR_error;
4237       }
4238     }
4239     return ACR_okay;
4240   }
4241 
4242   // The life-time qualifier cast check above is all we need for ObjCWeak.
4243   // ObjCAutoRefCount has more restrictions on what is legal.
4244   if (!getLangOpts().ObjCAutoRefCount)
4245     return ACR_okay;
4246 
4247   if (isAnyCLike(exprACTC) && isAnyCLike(castACTC)) return ACR_okay;
4248 
4249   // Allow all of these types to be cast to integer types (but not
4250   // vice-versa).
4251   if (castACTC == ACTC_none && castType->isIntegralType(Context))
4252     return ACR_okay;
4253 
4254   // Allow casts between pointers to lifetime types (e.g., __strong id*)
4255   // and pointers to void (e.g., cv void *). Casting from void* to lifetime*
4256   // must be explicit.
4257   if (exprACTC == ACTC_indirectRetainable && castACTC == ACTC_voidPtr)
4258     return ACR_okay;
4259   if (castACTC == ACTC_indirectRetainable && exprACTC == ACTC_voidPtr &&
4260       isCast(CCK))
4261     return ACR_okay;
4262 
4263   switch (ARCCastChecker(Context, exprACTC, castACTC, false).Visit(castExpr)) {
4264   // For invalid casts, fall through.
4265   case ACC_invalid:
4266     break;
4267 
4268   // Do nothing for both bottom and +0.
4269   case ACC_bottom:
4270   case ACC_plusZero:
4271     return ACR_okay;
4272 
4273   // If the result is +1, consume it here.
4274   case ACC_plusOne:
4275     castExpr = ImplicitCastExpr::Create(Context, castExpr->getType(),
4276                                         CK_ARCConsumeObject, castExpr,
4277                                         nullptr, VK_RValue);
4278     Cleanup.setExprNeedsCleanups(true);
4279     return ACR_okay;
4280   }
4281 
4282   // If this is a non-implicit cast from id or block type to a
4283   // CoreFoundation type, delay complaining in case the cast is used
4284   // in an acceptable context.
4285   if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC) && isCast(CCK))
4286     return ACR_unbridged;
4287 
4288   // Issue a diagnostic about a missing @-sign when implicit casting a cstring
4289   // to 'NSString *', instead of falling through to report a "bridge cast"
4290   // diagnostic.
4291   if (castACTC == ACTC_retainable && exprACTC == ACTC_none &&
4292       ConversionToObjCStringLiteralCheck(castType, castExpr, Diagnose))
4293     return ACR_error;
4294 
4295   // Do not issue "bridge cast" diagnostic when implicit casting
4296   // a retainable object to a CF type parameter belonging to an audited
4297   // CF API function. Let caller issue a normal type mismatched diagnostic
4298   // instead.
4299   if ((!DiagnoseCFAudited || exprACTC != ACTC_retainable ||
4300        castACTC != ACTC_coreFoundation) &&
4301       !(exprACTC == ACTC_voidPtr && castACTC == ACTC_retainable &&
4302         (Opc == BO_NE || Opc == BO_EQ))) {
4303     if (Diagnose)
4304       diagnoseObjCARCConversion(*this, castRange, castType, castACTC, castExpr,
4305                                 castExpr, exprACTC, CCK);
4306     return ACR_error;
4307   }
4308   return ACR_okay;
4309 }
4310 
4311 /// Given that we saw an expression with the ARCUnbridgedCastTy
4312 /// placeholder type, complain bitterly.
4313 void Sema::diagnoseARCUnbridgedCast(Expr *e) {
4314   // We expect the spurious ImplicitCastExpr to already have been stripped.
4315   assert(!e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
4316   CastExpr *realCast = cast<CastExpr>(e->IgnoreParens());
4317 
4318   SourceRange castRange;
4319   QualType castType;
4320   CheckedConversionKind CCK;
4321 
4322   if (CStyleCastExpr *cast = dyn_cast<CStyleCastExpr>(realCast)) {
4323     castRange = SourceRange(cast->getLParenLoc(), cast->getRParenLoc());
4324     castType = cast->getTypeAsWritten();
4325     CCK = CCK_CStyleCast;
4326   } else if (ExplicitCastExpr *cast = dyn_cast<ExplicitCastExpr>(realCast)) {
4327     castRange = cast->getTypeInfoAsWritten()->getTypeLoc().getSourceRange();
4328     castType = cast->getTypeAsWritten();
4329     CCK = CCK_OtherCast;
4330   } else {
4331     llvm_unreachable("Unexpected ImplicitCastExpr");
4332   }
4333 
4334   ARCConversionTypeClass castACTC =
4335     classifyTypeForARCConversion(castType.getNonReferenceType());
4336 
4337   Expr *castExpr = realCast->getSubExpr();
4338   assert(classifyTypeForARCConversion(castExpr->getType()) == ACTC_retainable);
4339 
4340   diagnoseObjCARCConversion(*this, castRange, castType, castACTC,
4341                             castExpr, realCast, ACTC_retainable, CCK);
4342 }
4343 
4344 /// stripARCUnbridgedCast - Given an expression of ARCUnbridgedCast
4345 /// type, remove the placeholder cast.
4346 Expr *Sema::stripARCUnbridgedCast(Expr *e) {
4347   assert(e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
4348 
4349   if (ParenExpr *pe = dyn_cast<ParenExpr>(e)) {
4350     Expr *sub = stripARCUnbridgedCast(pe->getSubExpr());
4351     return new (Context) ParenExpr(pe->getLParen(), pe->getRParen(), sub);
4352   } else if (UnaryOperator *uo = dyn_cast<UnaryOperator>(e)) {
4353     assert(uo->getOpcode() == UO_Extension);
4354     Expr *sub = stripARCUnbridgedCast(uo->getSubExpr());
4355     return new (Context)
4356         UnaryOperator(sub, UO_Extension, sub->getType(), sub->getValueKind(),
4357                       sub->getObjectKind(), uo->getOperatorLoc(), false);
4358   } else if (GenericSelectionExpr *gse = dyn_cast<GenericSelectionExpr>(e)) {
4359     assert(!gse->isResultDependent());
4360 
4361     unsigned n = gse->getNumAssocs();
4362     SmallVector<Expr *, 4> subExprs;
4363     SmallVector<TypeSourceInfo *, 4> subTypes;
4364     subExprs.reserve(n);
4365     subTypes.reserve(n);
4366     for (const GenericSelectionExpr::Association &assoc : gse->associations()) {
4367       subTypes.push_back(assoc.getTypeSourceInfo());
4368       Expr *sub = assoc.getAssociationExpr();
4369       if (assoc.isSelected())
4370         sub = stripARCUnbridgedCast(sub);
4371       subExprs.push_back(sub);
4372     }
4373 
4374     return GenericSelectionExpr::Create(
4375         Context, gse->getGenericLoc(), gse->getControllingExpr(), subTypes,
4376         subExprs, gse->getDefaultLoc(), gse->getRParenLoc(),
4377         gse->containsUnexpandedParameterPack(), gse->getResultIndex());
4378   } else {
4379     assert(isa<ImplicitCastExpr>(e) && "bad form of unbridged cast!");
4380     return cast<ImplicitCastExpr>(e)->getSubExpr();
4381   }
4382 }
4383 
4384 bool Sema::CheckObjCARCUnavailableWeakConversion(QualType castType,
4385                                                  QualType exprType) {
4386   QualType canCastType =
4387     Context.getCanonicalType(castType).getUnqualifiedType();
4388   QualType canExprType =
4389     Context.getCanonicalType(exprType).getUnqualifiedType();
4390   if (isa<ObjCObjectPointerType>(canCastType) &&
4391       castType.getObjCLifetime() == Qualifiers::OCL_Weak &&
4392       canExprType->isObjCObjectPointerType()) {
4393     if (const ObjCObjectPointerType *ObjT =
4394         canExprType->getAs<ObjCObjectPointerType>())
4395       if (const ObjCInterfaceDecl *ObjI = ObjT->getInterfaceDecl())
4396         return !ObjI->isArcWeakrefUnavailable();
4397   }
4398   return true;
4399 }
4400 
4401 /// Look for an ObjCReclaimReturnedObject cast and destroy it.
4402 static Expr *maybeUndoReclaimObject(Expr *e) {
4403   Expr *curExpr = e, *prevExpr = nullptr;
4404 
4405   // Walk down the expression until we hit an implicit cast of kind
4406   // ARCReclaimReturnedObject or an Expr that is neither a Paren nor a Cast.
4407   while (true) {
4408     if (auto *pe = dyn_cast<ParenExpr>(curExpr)) {
4409       prevExpr = curExpr;
4410       curExpr = pe->getSubExpr();
4411       continue;
4412     }
4413 
4414     if (auto *ce = dyn_cast<CastExpr>(curExpr)) {
4415       if (auto *ice = dyn_cast<ImplicitCastExpr>(ce))
4416         if (ice->getCastKind() == CK_ARCReclaimReturnedObject) {
4417           if (!prevExpr)
4418             return ice->getSubExpr();
4419           if (auto *pe = dyn_cast<ParenExpr>(prevExpr))
4420             pe->setSubExpr(ice->getSubExpr());
4421           else
4422             cast<CastExpr>(prevExpr)->setSubExpr(ice->getSubExpr());
4423           return e;
4424         }
4425 
4426       prevExpr = curExpr;
4427       curExpr = ce->getSubExpr();
4428       continue;
4429     }
4430 
4431     // Break out of the loop if curExpr is neither a Paren nor a Cast.
4432     break;
4433   }
4434 
4435   return e;
4436 }
4437 
4438 ExprResult Sema::BuildObjCBridgedCast(SourceLocation LParenLoc,
4439                                       ObjCBridgeCastKind Kind,
4440                                       SourceLocation BridgeKeywordLoc,
4441                                       TypeSourceInfo *TSInfo,
4442                                       Expr *SubExpr) {
4443   ExprResult SubResult = UsualUnaryConversions(SubExpr);
4444   if (SubResult.isInvalid()) return ExprError();
4445   SubExpr = SubResult.get();
4446 
4447   QualType T = TSInfo->getType();
4448   QualType FromType = SubExpr->getType();
4449 
4450   CastKind CK;
4451 
4452   bool MustConsume = false;
4453   if (T->isDependentType() || SubExpr->isTypeDependent()) {
4454     // Okay: we'll build a dependent expression type.
4455     CK = CK_Dependent;
4456   } else if (T->isObjCARCBridgableType() && FromType->isCARCBridgableType()) {
4457     // Casting CF -> id
4458     CK = (T->isBlockPointerType() ? CK_AnyPointerToBlockPointerCast
4459                                   : CK_CPointerToObjCPointerCast);
4460     switch (Kind) {
4461     case OBC_Bridge:
4462       break;
4463 
4464     case OBC_BridgeRetained: {
4465       bool br = isKnownName("CFBridgingRelease");
4466       Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
4467         << 2
4468         << FromType
4469         << (T->isBlockPointerType()? 1 : 0)
4470         << T
4471         << SubExpr->getSourceRange()
4472         << Kind;
4473       Diag(BridgeKeywordLoc, diag::note_arc_bridge)
4474         << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge");
4475       Diag(BridgeKeywordLoc, diag::note_arc_bridge_transfer)
4476         << FromType << br
4477         << FixItHint::CreateReplacement(BridgeKeywordLoc,
4478                                         br ? "CFBridgingRelease "
4479                                            : "__bridge_transfer ");
4480 
4481       Kind = OBC_Bridge;
4482       break;
4483     }
4484 
4485     case OBC_BridgeTransfer:
4486       // We must consume the Objective-C object produced by the cast.
4487       MustConsume = true;
4488       break;
4489     }
4490   } else if (T->isCARCBridgableType() && FromType->isObjCARCBridgableType()) {
4491     // Okay: id -> CF
4492     CK = CK_BitCast;
4493     switch (Kind) {
4494     case OBC_Bridge:
4495       // Reclaiming a value that's going to be __bridge-casted to CF
4496       // is very dangerous, so we don't do it.
4497       SubExpr = maybeUndoReclaimObject(SubExpr);
4498       break;
4499 
4500     case OBC_BridgeRetained:
4501       // Produce the object before casting it.
4502       SubExpr = ImplicitCastExpr::Create(Context, FromType,
4503                                          CK_ARCProduceObject,
4504                                          SubExpr, nullptr, VK_RValue);
4505       break;
4506 
4507     case OBC_BridgeTransfer: {
4508       bool br = isKnownName("CFBridgingRetain");
4509       Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
4510         << (FromType->isBlockPointerType()? 1 : 0)
4511         << FromType
4512         << 2
4513         << T
4514         << SubExpr->getSourceRange()
4515         << Kind;
4516 
4517       Diag(BridgeKeywordLoc, diag::note_arc_bridge)
4518         << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge ");
4519       Diag(BridgeKeywordLoc, diag::note_arc_bridge_retained)
4520         << T << br
4521         << FixItHint::CreateReplacement(BridgeKeywordLoc,
4522                           br ? "CFBridgingRetain " : "__bridge_retained");
4523 
4524       Kind = OBC_Bridge;
4525       break;
4526     }
4527     }
4528   } else {
4529     Diag(LParenLoc, diag::err_arc_bridge_cast_incompatible)
4530       << FromType << T << Kind
4531       << SubExpr->getSourceRange()
4532       << TSInfo->getTypeLoc().getSourceRange();
4533     return ExprError();
4534   }
4535 
4536   Expr *Result = new (Context) ObjCBridgedCastExpr(LParenLoc, Kind, CK,
4537                                                    BridgeKeywordLoc,
4538                                                    TSInfo, SubExpr);
4539 
4540   if (MustConsume) {
4541     Cleanup.setExprNeedsCleanups(true);
4542     Result = ImplicitCastExpr::Create(Context, T, CK_ARCConsumeObject, Result,
4543                                       nullptr, VK_RValue);
4544   }
4545 
4546   return Result;
4547 }
4548 
4549 ExprResult Sema::ActOnObjCBridgedCast(Scope *S,
4550                                       SourceLocation LParenLoc,
4551                                       ObjCBridgeCastKind Kind,
4552                                       SourceLocation BridgeKeywordLoc,
4553                                       ParsedType Type,
4554                                       SourceLocation RParenLoc,
4555                                       Expr *SubExpr) {
4556   TypeSourceInfo *TSInfo = nullptr;
4557   QualType T = GetTypeFromParser(Type, &TSInfo);
4558   if (Kind == OBC_Bridge)
4559     CheckTollFreeBridgeCast(T, SubExpr);
4560   if (!TSInfo)
4561     TSInfo = Context.getTrivialTypeSourceInfo(T, LParenLoc);
4562   return BuildObjCBridgedCast(LParenLoc, Kind, BridgeKeywordLoc, TSInfo,
4563                               SubExpr);
4564 }
4565