Metadata ICE in servo

[mmeyerho]

Servo can't build because of an ICE that shows up when building rust-glut. The branch fix_strings in https://github.com/mmeyerho/servo is syntax-compatible with the current rust master (6081eb7) up through glut. The backtrace is: https://gist.github.com/3133225. It looks like one of the fields of a tuple is trying to be pretty-printed but can't be looked up successfully.

[catamorphism]

Hate to ask, but did you try "make clean" and then rebuilding?

[mmeyerho]

Yeah, I've tried both that and complete rm'ing the build directory and autogen / configuring from scratch.

[msullivan]

Here is a minimized test case:

import task::{local_data_get, local_data_set};

fn display_callback_tls_key(+_callback: @int) {
    // Empty.
}

fn display_callback() unsafe {
    assert local_data_get(display_callback_tls_key).get() == @0;
}

fn main() {}

It looks like things are failing trying to come up with names for monomorphized functions. Maybe the problem is that a function inside the TLS implementation is invoking another one with a type that isn't getting put in the metadata...?

[catamorphism]

Could be yet another reachability bug, but I'm just guessing.

[msullivan]

Yeah, that's what my guess was. It can probably be worked around by adding more exports?

[msullivan]

Related to #2313, maybe?

[msullivan]

Exporting local_data works around the bug. It's clearly still a bug, but this fixes the ICE. I am labeling the export with a FIXME referencing this bug.

[bblum]

This bug is #2733.

[bblum]

I provided a minimal test case on that bug; closing this one. I remember doing exactly the same thing sully did here, which fixed the ICE, but that was #2734 was fixed, so I didn't push it.