ICE when #[no_mangle] function is declared multiple times with different signatures.

[mahkoh]

#![allow(dead_code)]

mod x {
    #[no_mangle]
    fn f() { }
}

mod y {
    #[no_mangle]
    fn f(_: i32) { }
}

fn main() { }

rustc: /build/rust-git/src/rust/src/llvm/include/llvm/Support/Casting.h:237: typename llvm::cast_retty<X, Y*>::ret_type llvm::cast(Y_) [with X = llvm::Function; Y = llvm::Value; typename llvm::cast_retty<X, Y_>::ret_type = llvm::Function*]: Assertion `isa(Val) && "cast() argument of incompatible type!"' failed.

[sfackler]

I could have sworn this had already been filed, but I can't find it.

[steveklabnik]

This still ICEs for me today.

[klutzy]

Dup of #10883?