ICE: With (unnecessary) extra generic argument

[japaric]

STR

trait MatrixShape {}

struct Col<D, C> {
    data: D,
    col: C,
}

// NB The `T` parameter is not necessary (it shouldn't be in the list), but it triggers the ICE
impl<T, M: MatrixShape> Collection for Col<M, uint> {
    fn len(&self) -> uint {
        unimplemented!()
    }
}

fn main() {}

Backtrace

ice.rs:9:1: 13:2 error: cannot determine a type for this bounded type parameter: unconstrained type
ice.rs:9 impl<T, M: MatrixShape> Collection for Col<M, uint> {
ice.rs:10     fn len(&self) -> uint {
ice.rs:11         unimplemented!()
ice.rs:12     }
ice.rs:13 }
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. 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
task 'rustc' failed at 't_f should be a trait', /var/tmp/paludis/build/dev-lang-rust-scm/work/rust-scm/src/librustc/middle/typeck/check/vtable.rs:572

stack backtrace:
   1:     0x7f0a70dc8cf0 - rt::backtrace::imp::write::hd882173939e2d158lxr
   2:     0x7f0a70dcbdc0 - <unknown>
   3:     0x7f0a715a2ce0 - unwind::begin_unwind_inner::h65c561bad0624ee8pie
   4:     0x7f0a719827f0 - <unknown>
   5:     0x7f0a71ef4f60 - <unknown>
   6:     0x7f0a71ef1df0 - <unknown>
   7:     0x7f0a71eb7ea0 - middle::ty::each_bound_trait_and_supertraits::h477415d2339bd77d4iJ
   8:     0x7f0a71ef1870 - <unknown>
   9:     0x7f0a71eef6b0 - <unknown>
  10:     0x7f0a71f002c0 - middle::typeck::check::vtable::resolve_impl::h5d941955100c3ed0hsN
  11:     0x7f0a71f5a4f0 - middle::typeck::check::check_item::h5c01327523eacc2cc8T
  12:     0x7f0a71f61190 - middle::typeck::check::check_item_types::h929141f69725396elyT
  13:     0x7f0a719757a0 - <unknown>
  14:     0x7f0a7216f3c0 - middle::typeck::check_crate::h17528f3293b3d1e3Nbl
  15:     0x7f0a7223d080 - driver::driver::phase_3_run_analysis_passes::hefc53f5f304abf28UMz
  16:     0x7f0a722381c0 - driver::driver::compile_input::h0bf12e1ffd3fd3430yz
  17:     0x7f0a722e56c0 - <unknown>
  18:     0x7f0a722e55d0 - <unknown>
  19:     0x7f0a722f8000 - <unknown>
  20:     0x7f0a722f7e00 - <unknown>
  21:     0x7f0a72d48bb0 - <unknown>
  22:     0x7f0a715f2a90 - <unknown>
  23:     0x7f0a715f2a80 - rust_try
  24:     0x7f0a715a0340 - unwind::try::hb59840f49a9c268eF6d
  25:     0x7f0a715a00e0 - task::Task::run::h16546e7aae493143Zcd
  26:     0x7f0a72d48970 - <unknown>
  27:     0x7f0a715a1f20 - <unknown>
  28:     0x7f0a70859000 - start_thread
  29:     0x7f0a71271269 - clone
  30:                0x0 - <unknown>

Version

rustc 0.12.0-pre (eff87bc9d 2014-08-17 13:11:06 +0000)

Note The ICE doesn't occurr in the playpen (master nor 0.11 snapshot). So the ICE must have been introduced in a recent commit.