impl Undefined {} gives impl coherence error, not unresolved name

[huonw]

impl Undefined {}

fn main() {}

<anon>:1:6: 1:15 error: inherent implementations are not allowed for types not defined in the current module.
<anon>:1 impl Undefined {}
              ^~~~~~~~~

This should say error: use of undeclared type name Undefined`` like fn foo() -> Undefined {} does.

[steveklabnik]

triage: still true today

[nham]

As of rustc 1.2.0-nightly (20d23d8e5 2015-06-18) the error is

18058.rs:1:6: 1:15 error: use of undeclared type name `Undefined`
18058.rs:1 impl Undefined {}
                ^~~~~~~~~
error: aborting due to previous error

I will add a regression test so this issue can be closed.