ICE with metadata, ifaces, and generic functions

[erickt]

Good morning,

I ran into an ICE when trying to return a generic implementation across a crate. Here's a reduced example of the bug:

https://gist.github.com/2689394

a.rs:

#[link(name = "a", vers = "0.0")];
#[crate_type = "lib"];

iface i<T> { }

fn f<T>() -> i<T> {
    impl <T> of i<T> for () { }

    () as i::<T>
}

b.rs:

use a;

fn main() {
    a::f::<()>();
}

Errors with:

./run-rustc a.rs
warning: no debug symbols in executable (-arch x86_64)
./run-rustc b.rs
rust: upcall fail 'lookup_item: id not found: 13', /Users/etryzelaar/Projects/rust/rust/src/rustc/metadata/decoder.rs:94
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=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: upcall fail 'explicit failure', /Users/etryzelaar/Projects/rust/rust/src/rustc/driver/rustc.rs:248
rust: domain main @0x103000010 root task failed
rust: upcall fail 'killed', /Users/etryzelaar/Projects/rust/rust/src/libcore/task.rs:454
make: *** [all] Error 101

[jdm]

This might be another example of #2318.

[erickt]

@jdm: It doesn't look like it. I just did a make clean && make and I'm still getting the same error.

[catamorphism]

Dup of #2383. Added the test as an additional test case.