Can't bring nested mod into scope with `use foo::foo`

[ben0x539]

The use foo::foo; line seems to do nothing at all, the reference to foo inside main still seems to resolve to the outer foo.

    mod foo {
        pub mod foo {
            pub fn f() {}
        }
    }

    use foo::foo;

    fn main() {
        foo::f();
    }

hw.rs:10:4: 10:10 error: unresolved name: foo::f
hw.rs:10     foo::f();
             ^~~~~~

Should the use item just be illegal if it collides with an existing name? This issue confused me for quite a while with the rust-sdl package's sdl crate that contains an sdl mod.

[catamorphism]

Seems non-critical for 0.7. Nominating for milestone #1 (well-defined).

[graydon]

This is an "expected no-shadowing, got shadowing" case. it now rejects at parse level because the use things must come first. (This is actually the case that rule was introduced to handle).