Cannot derive Clone for function pointers with reference args

[michaelwu]

http://is.gd/8pUCyO

#[derive(Copy, Clone)]
struct Foo {
    test: unsafe extern "C" fn(&u32)
}

outputs

<anon>:3:5: 3:37 error: the trait `core::clone::Clone` is not implemented for the type `unsafe extern "C" fn(&u32)` [E0277]
<anon>:3     test: unsafe extern "C" fn(&u32)
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<anon>:1:16: 1:21 note: in this expansion of #[derive_Clone] (defined in <anon>)
<anon>:3:5: 3:37 help: see the detailed explanation for E0277
<anon>:3:5: 3:37 note: required by `core::clone::Clone::clone`
error: aborting due to previous error

[michaelwu]

Looks like this is #10501