ICE using associated type from trait implemented for reference type

[jcmoyer]

Minimal code to reproduce:

trait Inner {
    type T;
}

impl<'a> Inner for &'a i32 {
    type T = i32;
}

fn f<'a>(x: &'a i32) -> <&'a i32 as Inner>::T {
    *x
}

fn main() {}

I was actually trying to implement this for &'a Option<T> so I could get the T out of Option<T>, but this produces the same error (although with &'a Option<T> I get a different backtrace, and it doesn't ICE until I actually use the function - so I'm not sure if it's a separate issue or not). It does not ICE when the references are removed, i.e. impl Inner for i32 and f(x: i32) -> <i32 as Inner>::T. Same for the Option<T> case.

Version:

rustc 1.0.0-nightly (30e1f9a1c 2015-03-14) (built 2015-03-15)
binary: rustc
commit-hash: 30e1f9a1c2bf7134135800bc9afd082773defadc
commit-date: 2015-03-14
build-date: 2015-03-15
host: i686-unknown-linux-gnu
release: 1.0.0-nightly

Error message and backtrace:

error: internal compiler error: fictitious type <&'static i32 as Inner>::T in sizing_type_of()
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 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:190

stack backtrace:
   1:   0xfe0a14 - sys::backtrace::write::hc52363cb69d92d49YyC
   2:  0x1007933 - panicking::on_panic::haa4c63d646619106OGI
   3:   0xf31989 - rt::unwind::begin_unwind_inner::h3622bffc67b74defmnI
   4: 0x1a4700fa - rt::unwind::begin_unwind::h17473118271825318944
   5: 0x1a4709ce - diagnostic::Handler::bug::ha5af5744723c82a6lgB
   6:  0x6c92b78 - session::Session::bug::h7830cc258e0a71f48vn
   7:   0x61e93f - trans::type_of::sizing_type_of::h65ea81377c3e14831wo
   8:   0x646f82 - trans::common::type_is_immediate::hf913e55ab71352abADk
   9:   0x6e91a4 - trans::type_of::type_of_rust_fn::he4cc5eff6b6755ba0ro
  10:   0x6f1ee3 - trans::base::decl_rust_fn::ha6f27bbe2af80566Qsr
  11:   0x701081 - trans::base::register_fn::ha69eafedc56aaa9590t
  12:   0x5fc507 - trans::base::get_item_val::h067715933c9d99b7Vnu
  13:   0x5f902a - trans::base::trans_item::h7f6909c63808f532CSt
  14:   0x706006 - trans::base::trans_crate::hea1a13db65a44e5ffPu
  15:   0x8f51ca - driver::phase_4_translate_to_llvm::h406ec02b84c498ackOa
  16:   0x8cef6e - driver::compile_input::hf7e4519402c8bacfRba
  17:   0x994888 - run_compiler::h3c0938d24865bfd7x2b
  18:   0x992209 - thunk::F.Invoke<A, R>::invoke::h12389329639459538829
  19:   0x9912a6 - rt::unwind::try::try_fn::h2311466047322169838
  20:  0x1088f7a - rust_try_inner
  21:  0x1088f53 - rust_try
  22:   0x99177e - thunk::F.Invoke<A, R>::invoke::h15816452122554159345
  23:   0xff60f4 - sys::thread::thread_start::h8d422a9a48991e61B1G
  24:   0x4d5d4b - start_thread
  25:   0x1ff9dd - <unknown>

[steveklabnik]

This still ICEs for me on today's nightly.