Non-module extern crate is not visible to imports

[nrc]

fn main() {
    extern crate core;
    use core::cell;
}

Should work but doesn't. Note that it is only imports that seem to be affected, in the above example, using core in a path in a type or expression work fine.

[ftxqxd]

I think the example in the issue is the intended behaviour, as use accepts a global path, while everything else uses a local path by default. self normally lets you use a local path in use, though, but that doesn't work either, so I guess this is a real bug.

[sfackler]

cc #18084

[nrc]

So, since use always uses absolute paths, fixing #18084 seems to be the way to resolve this.

[glaebhoerl]

See also rust-lang/rfcs#959.