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




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132868 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 69 insertions, 6 deletions

diff --git a/include/clang/AST/DeclObjC.h b/include/clang/AST/DeclObjC.h
index 0a4d864cd8..0e698607db 100644
--- a/include/clang/AST/DeclObjC.h
+++ b/include/clang/AST/DeclObjC.h
@@ -135,6 +135,9 @@ private:
   /// in, inout, etc.
   unsigned objcDeclQualifier : 6;
 
+  /// \brief Indicates whether this method has a related result type.
+  unsigned RelatedResultType : 1;
+  
   // Number of args separated by ':' in a method declaration.
   unsigned NumSelectorArgs;
 
@@ -171,6 +174,7 @@ private:
                  bool isSynthesized = false,
                  bool isDefined = false,
                  ImplementationControl impControl = None,
+                 bool HasRelatedResultType = false,
                  unsigned numSelectorArgs = 0)
   : NamedDecl(ObjCMethod, contextDecl, beginLoc, SelInfo),
     DeclContext(ObjCMethod), Family(InvalidObjCMethodFamily),
@@ -178,8 +182,8 @@ private:
     IsSynthesized(isSynthesized),
     IsDefined(isDefined),
     DeclImplementation(impControl), objcDeclQualifier(OBJC_TQ_None),
-    NumSelectorArgs(numSelectorArgs), MethodDeclType(T), 
-    ResultTInfo(ResultTInfo),
+    RelatedResultType(HasRelatedResultType), NumSelectorArgs(numSelectorArgs), 
+    MethodDeclType(T), ResultTInfo(ResultTInfo),
     EndLoc(endLoc), Body(0), SelfDecl(0), CmdDecl(0) {}
 
   /// \brief A definition will return its interface declaration.
@@ -199,6 +203,7 @@ public:
                                 bool isSynthesized = false,
                                 bool isDefined = false,
                                 ImplementationControl impControl = None,
+                                bool HasRelatedResultType = false,
                                 unsigned numSelectorArgs = 0);
 
   virtual ObjCMethodDecl *getCanonicalDecl();
@@ -211,6 +216,13 @@ public:
   }
   void setObjCDeclQualifier(ObjCDeclQualifier QV) { objcDeclQualifier = QV; }
 
+  /// \brief Determine whether this method has a result type that is related
+  /// to the message receiver's type.
+  bool hasRelatedResultType() const { return RelatedResultType; }
+  
+  /// \brief Note whether this method has a related result type.
+  void SetRelatedResultType(bool RRT = true) { RelatedResultType = RRT; }
+  
   unsigned getNumSelectorArgs() const { return NumSelectorArgs; }
   void setNumSelectorArgs(unsigned numSelectorArgs) { 
     NumSelectorArgs = numSelectorArgs; 
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 17356b963d..7890aefc50 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -4117,5 +4117,22 @@ def err_invalid_astype_of_different_size : Error<
 
 } // end of sema category
 
+let CategoryName = "Related Result Type Issue" in {
+// Objective-C related result type compatibility
+def warn_related_result_type_compatibility_class : Warning<
+  "method is expected to return an instance of its class type %0, but "
+  "is declared to return %1">;
+def warn_related_result_type_compatibility_protocol : Warning<
+  "protocol method is expected to return an instance of the implementing "
+  "class, but is declared to return %0">;
+def note_related_result_type_overridden : Note<
+  "overridden method is part of the '%select{|alloc|copy|init|mutableCopy|"
+  "new|autorelease|dealloc|release|retain|retainCount|self}0' method family">;
+def note_related_result_type_inferred : Note<
+  "%select{class|instance}0 method %1 is assumed to return an instance of "
+  "its receiver type (%2)">;
+
+}
+
 } // end of sema component.
 
diff --git a/include/clang/Basic/IdentifierTable.h b/include/clang/Basic/IdentifierTable.h
index 683ec8312e..b4eca6d8fb 100644
--- a/include/clang/Basic/IdentifierTable.h
+++ b/include/clang/Basic/IdentifierTable.h
@@ -498,7 +498,8 @@ enum ObjCMethodFamily {
   OMF_dealloc,
   OMF_release,
   OMF_retain,
-  OMF_retainCount
+  OMF_retainCount,
+  OMF_self
 };
 
 /// Enough bits to store any enumerator in ObjCMethodFamily or
diff --git a/include/clang/Basic/LangOptions.h b/include/clang/Basic/LangOptions.h
index a5f6789b7d..f0f1432ca0 100644
--- a/include/clang/Basic/LangOptions.h
+++ b/include/clang/Basic/LangOptions.h
@@ -46,6 +46,8 @@ public:
   unsigned ObjCNonFragileABI : 1;  // Objective-C modern abi enabled
   unsigned ObjCNonFragileABI2 : 1;  // Objective-C enhanced modern abi enabled
   unsigned ObjCDefaultSynthProperties : 1; // Objective-C auto-synthesized properties.
+  unsigned ObjCInferRelatedResultType : 1; // Infer Objective-C related return
+                                           // types
   unsigned AppleKext         : 1;  // Allow apple kext features.
 
   unsigned PascalStrings     : 1;  // Allow Pascal strings
@@ -173,6 +175,7 @@ public:
     GC = ObjC1 = ObjC2 = ObjCNonFragileABI = ObjCNonFragileABI2 = 0;
     AppleKext = 0;
     ObjCDefaultSynthProperties = 0;
+    ObjCInferRelatedResultType = 0;
     NoConstantCFStrings = 0; InlineVisibilityHidden = 0;
     C99 = C1X = Microsoft = Borland = CPlusPlus = CPlusPlus0x = 0;
     CXXOperatorNames = PascalStrings = WritableStrings = ConstStrings = 0;
diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 155ecae579..14d8f67b9d 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -493,6 +493,8 @@ def print_ivar_layout : Flag<"-print-ivar-layout">,
   HelpText<"Enable Objective-C Ivar layout bitmap print trace">;
 def fobjc_nonfragile_abi : Flag<"-fobjc-nonfragile-abi">,
   HelpText<"enable objective-c's nonfragile abi">;
+def fobjc_infer_related_result_type : Flag<"-fobjc-infer-related-result-type">,
+  HelpText<"infer Objective-C related result type based on method family">;
 def ftrapv : Flag<"-ftrapv">,
   HelpText<"Trap on integer overflow">;
 def ftrapv_handler : Separate<"-ftrapv-handler">,
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 23b351c78a..72039766d9 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -392,6 +392,10 @@ def fobjc_gc_only : Flag<"-fobjc-gc-only">, Group<f_Group>;
 def fobjc_gc : Flag<"-fobjc-gc">, Group<f_Group>;
 def fobjc_legacy_dispatch : Flag<"-fobjc-legacy-dispatch">, Group<f_Group>;
 def fobjc_new_property : Flag<"-fobjc-new-property">, Group<clang_ignored_f_Group>;
+def fobjc_infer_related_result_type : Flag<"-fobjc-infer-related-result-type">, 
+                                      Group<f_Group>;
+def fno_objc_infer_related_result_type : Flag<
+  "-fno-objc-infer-related-result-type">, Group<f_Group>;
 
 // Objective-C ABI options.
 def fobjc_abi_version_EQ : Joined<"-fobjc-abi-version=">, Group<f_Group>;
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index a1c0ba9dcf..bb3ec2dbed 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -4981,7 +4981,7 @@ public:
     SourceLocation EndLoc,   // location of the ; or {.
     tok::TokenKind MethodType,
     Decl *ClassDecl, ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
-    Selector Sel,
+    SourceLocation SelectorStartLoc, Selector Sel,
     // optional arguments. The number of types/arguments is obtained
     // from the Sel.getNumArgs().
     ObjCArgInfo *ArgInfo,
@@ -5079,7 +5079,18 @@ public:
                                   SourceLocation RBracLoc,
                                   MultiExprArg Args);
 
-
+  /// \brief Check whether the given new method is a valid override of the
+  /// given overridden method, and set any properties that should be inherited.
+  ///
+  /// \returns True if an error occurred.
+  bool CheckObjCMethodOverride(ObjCMethodDecl *NewMethod, 
+                               const ObjCMethodDecl *Overridden,
+                               bool IsImplementation);
+    
+  /// \brief Check whether the given method overrides any methods in its class,
+  /// calling \c CheckObjCMethodOverride for each overridden method.
+  bool CheckObjCMethodOverrides(ObjCMethodDecl *NewMethod, DeclContext *DC);
+  
   enum PragmaOptionsAlignKind {
     POAK_Native,  // #pragma options align=native
     POAK_Natural, // #pragma options align=natural
@@ -5501,11 +5512,24 @@ public:
   /// \param Method - May be null.
   /// \param [out] ReturnType - The return type of the send.
   /// \return true iff there were any incompatible types.
-  bool CheckMessageArgumentTypes(Expr **Args, unsigned NumArgs, Selector Sel,
+  bool CheckMessageArgumentTypes(QualType ReceiverType,
+                                 Expr **Args, unsigned NumArgs, Selector Sel,
                                  ObjCMethodDecl *Method, bool isClassMessage,
+                                 bool isSuperMessage,
                                  SourceLocation lbrac, SourceLocation rbrac,
                                  QualType &ReturnType, ExprValueKind &VK);
 
+  /// \brief Determine the result of a message send expression based on
+  /// the type of the receiver, the method expected to receive the message,
+  /// and the form of the message send.
+  QualType getMessageSendResultType(QualType ReceiverType,
+                                    ObjCMethodDecl *Method,
+                                    bool isClassMessage, bool isSuperMessage);
+    
+  /// \brief If the given expression involves a message send to a method
+  /// with a related result type, emit a note describing what happened.
+  void EmitRelatedResultTypeNote(const Expr *E);
+  
   /// CheckBooleanCondition - Diagnose problems involving the use of
   /// the given expression as a boolean condition (e.g. in an if
   /// statement).  Also performs the standard function and array