Implement Objective-C Related Result Type semantics.

Related result types apply Cocoa conventions to the type of message
sends and property accesses to Objective-C methods that are known to
always return objects whose type is the same as the type of the
receiving class (or a subclass thereof), such as +alloc and
-init. This tightens up static type safety for Objective-C, so that we
now diagnose mistakes like this:

t.m:4:10: warning: incompatible pointer types initializing 'NSSet *'
with an
      expression of type 'NSArray *' [-Wincompatible-pointer-types]
  NSSet *array = [[NSArray alloc] init];
         ^       ~~~~~~~~~~~~~~~~~~~~~~
/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:72:1:
note: 
      instance method 'init' is assumed to return an instance of its
      receiver
      type ('NSArray *')
- (id)init;
^

It also means that we get decent type inference when writing code in
Objective-C++0x:

  auto array = [[NSMutableArray alloc] initWithObjects:@"one",  @"two",nil];
  //    ^ now infers NSMutableArray* rather than id

llvm-svn: 132868

4 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 3c3993f412d..8fb20d22b7d 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -92,6 +92,7 @@ PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts) {
   PARSE_LANGOPT_IMPORTANT(AppleKext, diag::warn_pch_apple_kext);
   PARSE_LANGOPT_IMPORTANT(ObjCDefaultSynthProperties,
                           diag::warn_pch_objc_auto_properties);
+  PARSE_LANGOPT_BENIGN(ObjCInferRelatedResultType)
   PARSE_LANGOPT_IMPORTANT(NoConstantCFStrings,
                           diag::warn_pch_no_constant_cfstrings);
   PARSE_LANGOPT_BENIGN(PascalStrings);
@@ -2934,6 +2935,7 @@ bool ASTReader::ParseLanguageOptions(
     PARSE_LANGOPT(ObjCNonFragileABI2);
     PARSE_LANGOPT(AppleKext);
     PARSE_LANGOPT(ObjCDefaultSynthProperties);
+    PARSE_LANGOPT(ObjCInferRelatedResultType);
     PARSE_LANGOPT(NoConstantCFStrings);
     PARSE_LANGOPT(PascalStrings);
     PARSE_LANGOPT(WritableStrings);
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index d2b014842c1..6e9d4d48204 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -468,6 +468,7 @@ void ASTDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
   MD->setDefined(Record[Idx++]);
   MD->setDeclImplementation((ObjCMethodDecl::ImplementationControl)Record[Idx++]);
   MD->setObjCDeclQualifier((Decl::ObjCDeclQualifier)Record[Idx++]);
+  MD->SetRelatedResultType(Record[Idx++]);
   MD->setNumSelectorArgs(unsigned(Record[Idx++]));
   MD->setResultType(Reader.GetType(Record[Idx++]));
   MD->setResultTypeSourceInfo(GetTypeSourceInfo(Record, Idx));
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 194d6c31cfa..ba9032e0d33 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1050,6 +1050,7 @@ void ASTWriter::WriteLanguageOptions(const LangOptions &LangOpts) {
   Record.push_back(LangOpts.AppleKext);          // Apple's kernel extensions ABI
   Record.push_back(LangOpts.ObjCDefaultSynthProperties); // Objective-C auto-synthesized
                                                       // properties enabled.
+  Record.push_back(LangOpts.ObjCInferRelatedResultType);
   Record.push_back(LangOpts.NoConstantCFStrings); // non cfstring generation enabled..
 
   Record.push_back(LangOpts.PascalStrings);  // Allow Pascal strings
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 71eb5e82313..c6b159c50bc 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -404,6 +404,7 @@ void ASTDeclWriter::VisitObjCMethodDecl(ObjCMethodDecl *D) {
   Record.push_back(D->getImplementationControl());
   // FIXME: stable encoding for in/out/inout/bycopy/byref/oneway
   Record.push_back(D->getObjCDeclQualifier());
+  Record.push_back(D->hasRelatedResultType());
   Record.push_back(D->getNumSelectorArgs());
   Writer.AddTypeRef(D->getResultType(), Record);
   Writer.AddTypeSourceInfo(D->getResultTypeSourceInfo(), Record);