Merge pull request #26589 from xymus/dont-inherit-clang-availability

Don't apply the unavailability of an extension to members imported from Clang

Author: xymus

lib/AST/Attr.cpp

@@ -1073,8 +1073,15 @@ const AvailableAttr *AvailableAttr::isUnavailable(const Decl *D) {
     return attr;
 
   // If D is an extension member, check if the extension is unavailable.
-  if (auto ext = dyn_cast<ExtensionDecl>(D->getDeclContext()))
-    return AvailableAttr::isUnavailable(ext);
+  //
+  // Skip decls imported from Clang, they could be associated to the wrong
+  // extension and inherit undesired unavailability. The ClangImporter
+  // associates Objective-C protocol members to the first category where the
+  // protocol is directly or indirectly adopted, no matter its availability
+  // and the availability of other categories. rdar://problem/53956555
+  if (!D->getClangNode())
+    if (auto ext = dyn_cast<ExtensionDecl>(D->getDeclContext()))
+        return AvailableAttr::isUnavailable(ext);
 
   return nullptr;
 }

test/ClangImporter/Inputs/availability_platform_categories.h

@@ -0,0 +1,19 @@
+#import <Foundation/Foundation.h>
+
+@interface SharedInterface
+@end
+
+@protocol SharedProtocol <NSObject>
++ (NSInteger)foo;
+@end
+
+// ClangImporter imports the first category as the extension parent of
+// SharedInterface.foo, making foo unavailable on macOS when the extension
+// unavailability is inherited by its members.
+API_UNAVAILABLE(macos)
+@interface SharedInterface (IOSCategory) <SharedProtocol>
+@end
+
+API_UNAVAILABLE(ios)
+@interface SharedInterface (MacOSCategory) <SharedProtocol>
+@end

test/ClangImporter/availability_platform_categories.swift

@@ -0,0 +1,8 @@
+// RUN: %target-swift-frontend -typecheck %s -import-objc-header %S/Inputs/availability_platform_categories.h
+
+// REQUIRES: OS=macos
+
+// Test when a function is associated to an Objective-C category with the
+// wrong unavailability. rdar://problem/53956555
+
+print(SharedInterface.foo())