Tracking issue for RFC PR 385 - module system cleanup

[nrc]

• Remove the ordering requirement for mod, extern crate, and other items;
• allow extern crate in non-module blocks;
• allow pub extern crate.

[nrc]

These three are backwards compatible (so shouldn't block 1.0), however, the first in particular is a wart, so I think we'd be happy to see that fixed pre-1.0 at least.

[nrc]

RFC: https://github.com/rust-lang/rfcs/blob/master/text/0385-module-system-cleanup.md

[pnkfelix]

P-high, not 1.0 (though some would be happy to see a PR for this sooner).

[aturon]

@pnkfelix The message from the triage meeting says not 1.0, but the issue was put on the milestone anyway?

[aturon]

Nominating. From previous discussion it's not clear what milestone this belongs on, if any.

[pnkfelix]

Removing the ordering restriction would be nice for 1.0 (not 1.0-beta). The other two bullets are not necessary for 1.0.

1.0 milestone.

[nrc]

Note to self: work out what still needs to be done

[nikomatsakis]

@nrc

#![feature(core)]

pub extern crate core;

fn main() { }

compiles on play: http://is.gd/RZrZ5X

[nrc]

So, pub extern crate appears to work. extern crate in non-module blocks only seems to partially work. E.g.,:

#![feature(core)]

fn main () {
    extern crate core;
    let _ = core::cell::UnsafeCell::new(42i32);
}

Does not give an error. But, use core::cell; does not work - use expressions don't seem to be able to see the crate brought into scope.

The ordering restrictions are gone.

I'll close this issue an open one for the extern crate bug.

[glaebhoerl]

(which is #24219 for anyone else wondering)