internal compiler error: unexpected panic

[yggie]

Ran into another bug today, unfortunately the compiler doesn’t tell me any more than this:

error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'no entry found for key', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libcore/option.rs:329

stack backtrace:
   1:        0x10ecf3d4c - sys::backtrace::write::ha6579a44c93c5b13weu
   2:        0x10ed17c8f - failure::on_fail::hf4fc7d467c56f479rdB
   3:        0x10ec81bee - rt::unwind::begin_unwind_inner::h1798f590d33010eenVA
   4:        0x10ec822fa - rt::unwind::begin_unwind_fmt::hccfdf16b93d72dd3TTA
   5:        0x10ed1776e - rust_begin_unwind
   6:        0x10ed63f54 - panicking::panic_fmt::ha0a5c3fa6a3e8d87TQv
   7:        0x10ba43fbf - astconv::ast_ty_to_ty::unboxed_closure.30766
   8:        0x10b9de9d6 - astconv::ast_ty_to_ty::h2710260cb7deea76ujt
   9:        0x10ba6cfab - collect::ty_generics::hda890650500761b6lqv
  10:        0x10ba50ee4 - collect::trait_def_of_item::ha27c345daf14c8a6i1u
  11:        0x10ba4fd4f - collect::CollectTraitDefVisitor<'a, 'tcx>.visit..Visitor<'v>::visit_item::h84d53113dbbda134Ldu
  12:        0x10ba4ff7f - collect::CollectTraitDefVisitor<'a, 'tcx>.visit..Visitor<'v>::visit_item::h84d53113dbbda134Ldu
  13:        0x10ba8e82f - check_crate::unboxed_closure.31904
  14:        0x10ba8c971 - check_crate::he5dc8ed100b8048eYMy
  15:        0x10b483c4e - driver::phase_3_run_analysis_passes::h094520913aa775afVFa
  16:        0x10b46ac36 - driver::compile_input::h385f7696c25beae6Bba
  17:        0x10b529826 - run_compiler::he16877a561eaef1dR8b
  18:        0x10b526b73 - thunk::F.Invoke<A, R>::invoke::h6774480594258817770
  19:        0x10b5259d8 - rt::unwind::try::try_fn::h5509419198239539026
  20:        0x10ed8d3a9 - rust_try_inner
  21:        0x10ed8d396 - rust_try
  22:        0x10b526016 - thunk::F.Invoke<A, R>::invoke::h1573488770652611368
  23:        0x10ed03611 - sys::thread::thread_start::h4a3cbd9668f8d1c3K6w
  24:     0x7fff88ea52fc - _pthread_body
  25:     0x7fff88ea5279 - _pthread_body

I managed to reproduce the issue with this snippet: http://is.gd/yUKE00

This is the output from rustc --verbose --version:

rustc 1.0.0-nightly (4e4e8cff1 2015-01-24 22:14:14 +0000)
binary: rustc
commit-hash: 4e4e8cff1697ec79bcd0a1e45e63fb2f54a7ea28
commit-date: 2015-01-24 22:14:14 +0000
host: x86_64-apple-darwin
release: 1.0.0-nightly

[nagisa]

Can confirm. Even more minimal test case

#![crate_type="rlib"]
pub trait Foo where Self::Bar: Sized {
}

[nagisa]

Duplicate of #21140

[Gankra]

Thanks for the sleuthing, @nagisa!