`#[no_mangle]` on associated functions

This program works with rustc, but not in Miri (playground):

struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}

fn main() {
    extern "Rust" {
        fn foo();
    }
    AssocFn::foo();
    unsafe { foo() }
}

(And unlike #[no_mangle] on normal functions, if AsocFn::foo is not used directly, it also does not work with rustc: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=f1244afcdd26e2a28445f6e82ca46b50.)

cc #1833 (comment)

[RalfJung]

(And unlike #[no_mangle] on normal functions, if AsocFn::foo is not used directly, it also does not work with rustc: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=f1244afcdd26e2a28445f6e82ca46b50.)

That sounds like a rustc bug?

rust-lang/rust#76211 looks related. I have a patch that fixes my playground example above and non-public associated functions in rlib crates for rustc. I haven't tested it for Miri and the rustc issue yet.