smeenai added a comment.
Sorry for the late feedback here – we're in the process of testing with Clang
10 and noticed a behavior change caused by this commit.
Consider the following piece of code:
@protocol P
@end
@protocol Q
@end
@interface I <P>
@end
@interface J : I <Q>
@end
void f(void (^)(id<P>));
void g() {
f(^(J *j){});
}
Clang 9 would accept it, whereas Clang 10 complains about incompatible block
pointer types. If I change the declaration of `J` to instead be:
@interface J : I
Both Clang 9 and Clang 10 accept it.
I'm not very familiar with Objective-C semantics. Does saying `@interface J : I
<Q>` mean we're overriding the conformance being specified by `@interface I
<P>`? In that case, the Clang 10 error makes sense to me.
In practice though, classes like `UIImage` are declared as inheriting from
`NSObject<NSSecureCoding>`, so passing a `UIImage *` to a block with a
parameter of type `id<NSObject>` gives an error with Clang 10.
Repository:
rL LLVM
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D66831/new/
https://reviews.llvm.org/D66831
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