uses in crate root shadow crates in inner modules

[mind-zz]

extern crate sync;
use std::sync;

mod inner {  use sync::RWArc;  }

rustc errors:

foo.rs:4:17: 4:28 error: unresolved import: there is no RWArc in std::sync

(rustc 0.10-pre (6720977 2014-02-24 04:11:53 -0800))

[alexcrichton]

Closing as working as intended. This is what the syntaxes extern crate foo = "bar" and use foo = bar are used for (resolving name conflicts).

[mind-zz]

Even across different modules? It's unintuitive that the use declarations in foo.rs would be affecting the use declarations in inner.rs. Although the problem would be quite apparent if name collisions resulted in an error.

[alexcrichton]

Oops sorry, misread! That's indeed a bug.

[huonw]

I think it makes perfect sense to shadow if these were pub use... but since they're not, and so this is very weird (especially as one often puts code in the crate root, and so the uses are necessary).

#7663 and #10884 are similar, but I think this case is a particularly bad consequence of our use rules.

[alexcrichton]

Nominating. This itself is not a backwards compatibility hazard (it's just a bug), but nearly every tweak I've made to resolve has broken many programs before. Thankfully, this program does not compile:

use std::c_str;

mod foo {
    use c_str;
}

However, I think we should fix this before 1.0 to be sure that we don't accidentally break programs.

[pnkfelix]

Assigning 1.0, P-high.