On rustc 1.0.0-nightly (2b01a37 2015-02-21) (built 2015-02-21) the follow causes an ICE:

trait Expr : PartialEq<Self::Item> {
    type Item = Expr;
}

fn main() {}

Full backtrace:
error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with RUST_BACKTRACE=1 for a backtrace
thread 'rustc' panicked at 'assertion failed: did.krate != ast::LOCAL_CRATE', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/librustc/middle/ty.rs:5461

stack backtrace:
1: 0x10b7aebe3 - sys::backtrace::write::hc8e3cee73e646c590nC
2: 0x10b7dcbe5 - panicking::on_panic::h00b47941f5bc8a02HOL
3: 0x10b706418 - rt::unwind::begin_unwind_inner::h539538ef7f909326UvL
4: 0x108472895 - rt::unwind::begin_unwind::h7610573592537740396
5: 0x1087eb7dc - middle::ty::lookup_trait_def::h00103e323589b59cNla
6: 0x108812687 - middle::ty::predicates_for_trait_ref::h59dd4f8104908ae1Vna
7: 0x10880c125 - middle::traits::util::Elaborator<'cx, 'tcx>.Iterator::next::h9dd8ee47ae7ea8d3QkV
8: 0x108811fd1 - middle::traits::util::Supertraits<'cx, 'tcx>.Iterator::next::h2583ba3461accfb9rnV
9: 0x108109246 - astconv::ast_ty_to_ty::closure.34580
10: 0x1080a36cb - astconv::ast_ty_to_ty::hb64a583bfbbc7b64Ncw
11: 0x1080ff44d - astconv::ast_ty_arg_to_ty::h51a53c78e1218ba4sbw
12: 0x1080feff0 - vec::Vec.FromIterator::from_iter::h8575313848639105278
13: 0x1080fc2e0 - astconv::convert_angle_bracketed_parameters::h9209f0db8109fac9biv
14: 0x108101457 - astconv::ast_path_to_trait_ref::h2a3b7b2e77e3fde5Vvv
15: 0x1080af1fb - astconv::instantiate_trait_ref::h65c5bb030d486323Csv
16: 0x1081007ea - astconv::instantiate_poly_trait_ref::hb7df5c75231f22c61qv
17: 0x10813049f - collect::compute_bounds::h0eb0cb5207e10f2ccTy
18: 0x10811270f - collect::trait_def_of_item::hb48744a94bcef339Q2x
19: 0x108110c0f - collect::CollectTraitDefVisitor<'a, 'tcx>.visit..Visitor<'v>::visit_item::h4c7bef27b106e20cS8w
20: 0x10815d07f - check_crate::closure.35774
21: 0x10815b02e - check_crate::hbe2eb4aab434ad7cVjC
22: 0x107ac68db - driver::phase_3_run_analysis_passes::h50728865d3ffa6b2gHa
23: 0x107aabb9d - driver::compile_input::h349b039ebe75c13eGba
24: 0x107b84857 - run_compiler::h1e4d87c6044fbf6dZbc
25: 0x107b81cd1 - thunk::F.Invoke<A, R>::invoke::h2059937391804860278
26: 0x107b80930 - rt::unwind::try::try_fn::h11862807381821880905
27: 0x10b8567e9 - rust_try_inner
28: 0x10b8567d6 - rust_try
29: 0x107b81095 - thunk::F.Invoke<A, R>::invoke::h6573516661401600357
30: 0x10b7c5ac3 - sys::thread::thread_start::h9e3555425c6999b2e4G
31: 0x7fff8fd0d268 - _pthread_body
32: 0x7fff8fd0d1e5 - _pthread_body