Protocol methods missing from classes

[stuartmorgan-g]

(There's a bit of related discussion in #1462, but this is a distinct issue.)

I'm unable to call methods on an object that come from a protocol, even when they are required methods. The concrete case I hit is:

@interface AVAsset : NSObject <NSCopying, AVAsynchronousKeyValueLoading>
...
@end

@protocol AVAsynchronousKeyValueLoading
@required

- (AVKeyValueStatus)statusOfValueForKey:(NSString *)key error:(NSError * _Nullable * _Nullable)outError ...;

- (void)loadValuesAsynchronouslyForKeys:(NSArray<NSString *> *)keys completionHandler:(nullable void (^)(void))handler ...;
@end

In Obj-C code I can then of course call:

[asset statusOfValueForKey:@"tracks" error:nil] != AVKeyValueStatusLoaded

But that method simply doesn't exist on AVAsset in the ffigen output, even though it's an explicit part of the public interface.

[liamappelbe]

Looks like we're bitten by limitations of libclang again. Traversing the children of the interface declaration cursor, I find a CXCursor_ObjCProtocolRef for each of the protocols it implements. But there's no way of getting from the CXCursor_ObjCProtocolRef to the CXCursor_ObjCProtocolDecl. The only information on the CXCursor_ObjCProtocolRef is the name of the protocol (it doesn't even have a usr ID). So the best I can do is look up the protocol by name and throw an error if there's more than one protocol declared with that name. This should cover most of the use cases at least.

Nevermind, turns out clang_getCursorDefinition works in this case. 😅

[stuartmorgan-g]

Do I need to do something special in my config to pick up the protocol? I synced to the hash with that fix, and still don't have the methods described in the original issue description.

[liamappelbe]

@stuartmorgan No, you shouldn't need to do anything. Can you send me your config? I'll see if I can repro. There might be a second bug here.

[stuartmorgan-g]

My actual repro case is here, but I think this should be the relevant parts (I haven't set up a clean test with this though):

name: Foo
description: Test
language: objc
output:
  bindings: 'ffi_bindings.dart'
  objc-bindings: 'ffi_bindings.dart.m'
headers:
  entry-points:
    - '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/System/Library/Frameworks/AVFoundation.framework/Headers/AVFoundation.h'
exclude-all-by-default: true
objc-interfaces:
  include:
    - 'AVAudioSession'
    - 'AVMutableVideoCompositionInstruction'
    - 'AVMutableVideoCompositionLayerInstruction'
    - 'AVPlayer'
    - 'AVPlayerLayer'
enums:
  include:
    - 'AVAudioSessionCategoryOptions'

[liamappelbe]

Ah ok. The issue is that the protocol is not being included by the config. I think probably the correct behavior here is that protocols that an interface conforms to should always be included in the interface's methods, regardless of the filters (or rather they should go through the same method filtering as ordinary methods). But we should only generate bindings for the protocol itself if the protocol is included in the filter.