ICE: using associated types in extern function signature

[jorisgio]

I get an ICE with similar code to this testcase : (rustc 1.3.0 (9a92aaf19 2015-09-15))

trait Test {
   type T;
}

impl Test for u32 {
   type T = i32;
}

pub type I = <u32 as Test>::T;

pub extern "C" fn test(t : I) {}

trace :

thread 'rustc' panicked at 'Box<Any>', ../src/libsyntax/diagnostic.rs:253

stack backtrace:
   1:     0x7f32612f68ee - sys::backtrace::write::haf6e4e635ac76143Ivs
   2:     0x7f32612fefd5 - panicking::on_panic::ha085a58a08f78856lzx
   3:     0x7f32612bfbce - rt::unwind::begin_unwind_inner::hc90ee27246f12475C0w
   4:     0x7f325e6dc76c - rt::unwind::begin_unwind::h11988818671084554314
   5:     0x7f325e6de0eb - diagnostic::Handler::bug::h57b1fbd717704399sdB
   6:     0x7f325f2c95a8 - session::Session::bug::h42a2bcf9b9358d7aFRt
   7:     0x7f32600d2073 - trans::type_of::in_memory_type_of::h0b2beb6279eadc99CmN
   8:     0x7f32600d1abc - trans::type_of::in_memory_type_of::h0b2beb6279eadc99CmN
   9:     0x7f32600d4191 - trans::type_of::type_of::hc9e8f77b11cdf8c20lN
  10:     0x7f32601b5473 - vec::Vec<T>.FromIterator<T>::from_iter::h8884525770310809719
  11:     0x7f32601b4eb0 - trans::foreign::foreign_signature::h983512416c3490efwOF
  12:     0x7f32601b4ac9 - trans::foreign::foreign_types_for_fn_ty::hacded173730270321PF
  13:     0x7f3260105a5c - trans::foreign::register_rust_fn_with_foreign_abi::hfd00bac55a193331xgF
  14:     0x7f32600ffa12 - trans::base::get_item_val::hd0ae7a460f0d2610BBj
  15:     0x7f32600fba29 - trans::base::trans_item::hae00c0ff97548410Pdj
  16:     0x7f326010856c - trans::base::trans_crate::h001f92a4a2fe58ffi0j
  17:     0x7f32618705d4 - driver::phase_4_translate_to_llvm::h2c6a45f20e7923ee5Oa
  18:     0x7f326186ab65 - driver::phase_3_run_analysis_passes::closure.16545
  19:     0x7f3261864d91 - middle::ty::ctxt<'tcx>::create_and_enter::h17619121053301903364
  20:     0x7f326185fc71 - driver::phase_3_run_analysis_passes::h12169435128770927116
  21:     0x7f3261843d70 - driver::compile_input::h50576600c327a48aTba
  22:     0x7f326192a083 - run_compiler::h08c4308e3023ae95A7b
  23:     0x7f3261927afe - boxed::F.FnBox<A>::call_box::h5719507417069443679
  24:     0x7f3261927429 - rt::unwind::try::try_fn::h17024725433081724618
  25:     0x7f32612feacd - __rust_try
  26:     0x7f32612e9b77 - rt::unwind::try::inner_try::h59523aa853a0e10avWw
  27:     0x7f3261927648 - boxed::F.FnBox<A>::call_box::h16487981074879516847
  28:     0x7f32612fdc11 - sys::thread::Thread::new::thread_start::h890d1188505773c835v
  29:     0x7f325b9650a3 - start_thread
  30:     0x7f3260f5404c - clone
  31:                0x0 - <unknown>