Cross-crate generics result in strange error.

[mstewartgallus]

Okay, so I really don't know how to title this error properly but cross-crate generics can result in this strange error. The error:

RUST_LOG=1 rustc main.rs -L .
rust: task failed at 'assertion failed: `(left == right) && (right == left)` (left: `2`, right: `0`)', /home/steven/others/src/rust/src/librustc/middle/trans/callee.rs:398
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /home/steven/others/src/rust/src/librustc/rustc.rs:362
rust: domain main @0xa75010 root task failed

main.rs

extern mod myextra;

use myextra::WriteLocked;

fn main() {
    let _foo: WriteLocked<()> = WriteLocked::new();
}

myextra.rs

#[crate_type = "lib"];

impl <T> WriteLocked<T> {
    pub fn new() -> WriteLocked<T> {
        WriteLocked(())
    }
}

pub struct WriteLocked<T> (());

Even weirder is the error that results when WriteLocked(()) is used directly in main.rs:

main.rs:6:32: 6:48 error: mismatched types: expected `myextra::WriteLocked<()>` but found `myextra::WriteLocked<BUG[0]>` (expected () but found type parameter)
main.rs:6     let _foo: WriteLocked<()> = WriteLocked(());
                                          ^~~~~~~~~~~~~~~~

[huonw]

Looks like a dup of #4545 and #7899 respectively for the two different errors. Closing in favour of them.