[objc] -[NSObject init] is documented to not do anything, don't warn if subclasses do not call [super init] on their initializers.

Part of rdar://16568441

llvm-svn: 206410

clang/lib/Sema/SemaDecl.cpp

@@ -9976,8 +9976,20 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
           MD->isDesignatedInitializerForTheInterface(&InitMethod);
       assert(isDesignated && InitMethod);
       (void)isDesignated;
-      // Don't issue this warning for unavaialable inits.
+
-      if (!MD->isUnavailable()) {
+      auto superIsNSObject = [&](const ObjCMethodDecl *MD) {
+        auto IFace = MD->getClassInterface();
+        if (!IFace)
+          return false;
+        auto SuperD = IFace->getSuperClass();
+        if (!SuperD)
+          return false;
+        return SuperD->getIdentifier() ==
+            NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
+      };
+      // Don't issue this warning for unavailable inits or direct subclasses
+      // of NSObject.
+      if (!MD->isUnavailable() && !superIsNSObject(MD)) {
         Diag(MD->getLocation(),
              diag::warn_objc_designated_init_missing_super_call);
         Diag(InitMethod->getLocation(),

clang/test/SemaObjC/attr-designated-init.m

@@ -354,7 +354,7 @@ __attribute__((objc_root_class))
 
 __attribute__((objc_root_class))
 @interface NSObject
--(instancetype) init NS_DESIGNATED_INITIALIZER;
+-(instancetype) init NS_DESIGNATED_INITIALIZER; // expected-note {{method marked as designated initializer of the class here}}
 @end
 
 @interface Test3 : NSObject
@@ -368,3 +368,23 @@ __attribute__((objc_root_class))
   return [self initWithBasePath:0];
 }
 @end
+
+@interface Test1 : NSObject
+-(instancetype) init NS_DESIGNATED_INITIALIZER;
+@end
+@implementation Test1
+-(instancetype) init {
+  return self;
+}
+@end
+
+
+@interface Test2 : NSObject
+@end
+@interface SubTest2 : Test2
+@end
+@implementation SubTest2
+-(instancetype) init { // expected-warning {{designated initializer missing a 'super' call to a designated initializer of the super class}}
+  return self;
+}
+@end