Lifetime bounds in Copy impls are ignored

[arielb1]

UPDATE: Mentoring instructions below.

---

Affected Versions

rustc 1.3.0 - 1.5.0

STR

#[derive(Clone)] struct Foo<'a>(&'a u32);
impl Copy for Foo<'static> {}

fn main() {
    let s = 2;
    let a = Foo(&s);
    drop(a);
    drop(a);
}

Expected Result

Foo<'a> is not Copy, so this should cause a borrowck error.

Actual Result

The code compiles :-).

cc @nikomatsakis

[nikomatsakis]

Nominating.

[nikomatsakis]

triage: P-high

[nikomatsakis]

Correct behavior here is not entirely obvious, given that we erase lifetimes at trans. Possibly we should be treating this affine, or possibly the impl should be an error? Have to mull this over.

cc @rust-lang/lang

[nikomatsakis]

Nominating for discussion at the lang meeting.