ICE encountered on pattern guard of nested match

[burg]

-*- mode: compilation; default-directory: "~/Desktop/" -*-
Compilation started at Wed Sep 26 16:06:54

RUST_LOG=rustc=0,::rt::backtrace rustc test.rc
rust: task failed at 'Assertion pats.is_not_empty() failed', /Users/burg/repos/rust/src/rustc/middle/check_alt.rs:83
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: task failed at 'explicit failure', /Users/burg/repos/rust/src/rustc/driver/rustc.rs:283
rust: domain main @0x7fe42c000010 root task failed
rust: task failed at 'killed', /Users/burg/repos/rust/src/libcore/task.rs:781

Compilation exited abnormally with code 101 at Wed Sep 26 16:06:54

[burg]

Here's a minimized test case: https://gist.github.com/3791204

[catamorphism]

Possible dup of #2869

[burg]

Maybe related, but the backtrace seemed to be different. Methinks someone needs to do a code review of pattern/guard code :-)

[catamorphism]

Code... re...view? ;-)

[nikomatsakis]

I believe the two bugs are independent. I THINK #2869 is a crash in trans vs this which appears to be a crash in the exhaustiveness checking code.

[youknowone]

This does not produce ICE on HEAD anymore.

[catamorphism]

@youknowone As of 82062a6 , this code does still produce the same ICE that was originally reported.

[youknowone]

I've run old test. thanks.

[catamorphism]

Can close once #5152 (fixing the test case) lands.