[PATCH] D66831: [ObjC] Fix type checking for qualified id block parameters.

[Volodymyr Sapsai via Phabricator via llvm-commits]

vsapsai added a comment.

In D66831#1650015 <https://reviews.llvm.org/D66831#1650015>, @thakis wrote:

> We're getting a bunch of errors looking like `../../AppsListViewController.m:11:37: error: incompatible block pointer types assigning to 'void (^)(__strong id<AppCellProtocol>)' from 'void (^)(AppCollectionViewCell *__strong)'` on code that looks fairly harmless to me. It looks something like this:
>
>   @protocol AppCellProtocol <NSObject> ... @end
>   @interface AppCollectionViewCell : NSObject <AppCellProtocol> ... at enderby 
>  
>   @interface Cell : NSObject
>   @property(nonatomic, copy) void (^buttonPressed)(id<AppCellProtocol> cell);
>   @end
>  
>   @implementation Bar
>   - (void) f {
>     __weak __typeof(self) weakSelf = self;
>     cell.buttonPressed = ^(AppCollectionViewCell *pressedCell) {
>       // ...
>     };
>   }
>   @end
>
>
> The code doesn't say `__strong` anywhere as far as I can tell; it looks like regular protocol code.
>
> Is this expected?


That's the intention of the change. When you call `void (^buttonPressed)(id<AppCellProtocol> cell)`, it is only enforced that the argument conforms to `AppCellProtocol`. But you can do

  cell.buttonPressed = ^(AppCollectionViewCell *pressedCell) {
    // call some AppCollectionViewCell method not present in AppCellProtocol
  };

and get unrecognized selector error. The change should help to avoid such situations.

Does my reasoning look correct to you?


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66831/new/

https://reviews.llvm.org/D66831