[ObjC Availability] Fix false positive of -Wpartial-availability introduced in r277058

[erik.pilkington]

Summary

As of r277058, Clang would incorrectly emit -Wpartial-availability for the following (when compiled with -mmacosx-verison-min=10.6):

int fn_10_5() __attribute__((availablity(macos, introduced=10.5)));
int use() __attribute__((availability(macos, introduced=10.4))) {
  return fn_10_5(); // incorrect warning: fn_10_5 is partial
}

The problem is that I didn't consider the base deployment target when getting the context version, so the availability of the context of the call to fn_10_5 was 10.4 (from the function), not 10.6 (from the deployment target). Therefore, a warning was emitted.

Thanks Nico Weber for pointing this out!

[thakis]

Thanks for the quick fix!

lib/Sema/SemaDeclAttr.cpp

     Interface = ID->getClassInterface();
 
   if (Interface) {
     if (const auto *AA = getAttrForPlatform(getASTContext(), Interface))
       if (AA->getIntroduced() > DeclVersion)
         DeclVersion = AA->getIntroduced();
   }
 
-  return DeclVersion;
+  return std::max(DeclVersion, Context.getTargetInfo().getPlatformMinVersion());
 }

test/SemaObjC/attr-availability.m

 -(void)method {
   InheritUnavailableSuper *obj = self;
   [obj method]; // expected-error{{'method' is unavailable}}
 }
 @end
 
 #if defined(WARN_PARTIAL)
 
+int fn_10_0() __attribute__((availability(macosx, introduced=10.0)));
 int fn_10_7() __attribute__((availability(macosx, introduced=10.7))); // expected-note{{marked partial here}}
 int fn_10_8() __attribute__((availability(macosx, introduced=10.8))) { // expected-note{{marked partial here}}
   return fn_10_7();
 }
 
 __attribute__((objc_root_class))
 @interface LookupAvailabilityBase
 -(void) method1;

 @end
 
 @implementation LookupAvailability
 -(void)method2 { fn_10_7(); }
 -(void)method3 { fn_10_8(); } // expected-warning{{partial}} expected-note{{explicitly redeclare}}
 -(void)method4 { fn_10_8(); }
 @end
 
+int old_func() __attribute__((availability(macos, introduced=10.4))) {
+  fn_10_0();
+}
+
 #endif