ICE: fictitious type <i32 as ToRef>::Ref in sizing_type_of()

[jp-beaumont]

This example causes an internal compiler error:

pub trait ToRef<'a> {
    type Ref: 'a;
}

impl<'a, U: 'a> ToRef<'a> for U {
    type Ref = &'a U;
}

fn example<'a, T>(value: &'a T) -> (<T as ToRef<'a>>::Ref, u32) {
    (value, 0)
}

fn main() {
    example(&0);
}

Small changes to example or main such as eliminating the tuple or printing the result produce working code.

Version:

rustc 1.14.0-nightly (a3bc191b5 2016-10-10)
binary: rustc
commit-hash: a3bc191b5f41df5143cc65084b13999896411817
commit-date: 2016-10-10
host: x86_64-unknown-linux-gnu
release: 1.14.0-nightly

Errror message and backtrace:

error: internal compiler error: ../src/librustc_trans/type_of.rs:98: fictitious type <i32 as ToRef>::Ref 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>', ../src/librustc_errors/lib.rs:656
stack backtrace:
   1:     0x7f3497eb9aef - std::sys::backtrace::tracing::imp::write::h22f199c1dbb72ba2
   2:     0x7f3497ec901d - std::panicking::default_hook::{{closure}}::h9a389c462b6a22dd
   3:     0x7f3497ec6496 - std::panicking::default_hook::h852b4223c1c00c59
   4:     0x7f3497ec6b78 - std::panicking::rust_panic_with_hook::hcd9d05f53fa0dafc
   5:     0x7f3494325607 - std::panicking::begin_panic::h2f463d37998ebeba
   6:     0x7f3494335768 - rustc_errors::Handler::bug::haca77c19c882b432
   7:     0x7f349538aa9a - rustc::session::opt_span_bug_fmt::{{closure}}::hfeb850fbe828b399
   8:     0x7f34952c9ba5 - rustc::session::opt_span_bug_fmt::h46e45438a860a75e
   9:     0x7f34952c99e2 - rustc::session::bug_fmt::hde22f071bf5a80ea
  10:     0x7f3496b20147 - rustc_trans::type_of::sizing_type_of::hf7867aeeebdabbb0
  11:     0x7f3496abc480 - rustc_trans::common::type_is_immediate::h93795cb753d0e711
  12:     0x7f3496abc6f0 - rustc_trans::common::type_is_imm_pair::h7e59f57fc9ab4576
  13:     0x7f3496b097b9 - rustc_trans::mir::operand::<impl rustc_trans::mir::MirContext<'bcx, 'tcx>>::trans_load::h2c9d8b0a9e8182b8
  14:     0x7f3496aff4cb - rustc_trans::mir::block::<impl rustc_trans::mir::MirContext<'bcx, 'tcx>>::store_return::h4d500d9c42a44cf7
  15:     0x7f3496afc4f9 - rustc_trans::mir::block::<impl rustc_trans::mir::MirContext<'bcx, 'tcx>>::trans_block::he67d3259f79e4177
  16:     0x7f3496af6b58 - rustc_trans::mir::trans_mir::h2fb44ecb31cfdffa
  17:     0x7f3496a98cdc - rustc_trans::base::trans_closure::h941de14309416d66
  18:     0x7f3496b16a34 - rustc_trans::trans_item::TransItem::define::ha4a18b94a3d46bf3
  19:     0x7f3496a9c254 - rustc_trans::base::trans_crate::h9b06de31ed8799d1
  20:     0x7f349824ed4d - rustc_driver::driver::phase_4_translate_to_llvm::hc3883ea2c4750179
  21:     0x7f3498289cf7 - rustc_driver::driver::compile_input::{{closure}}::h9162a2fa292aeb3f
  22:     0x7f3498280ef3 - rustc_driver::driver::phase_3_run_analysis_passes::{{closure}}::h1928c4704cfe9c61
  23:     0x7f349824c6ed - rustc_driver::driver::phase_3_run_analysis_passes::he578df6b8805151c
  24:     0x7f3498238f69 - rustc_driver::driver::compile_input::h5b63ccd49eeeb98b
  25:     0x7f34982622ba - rustc_driver::run_compiler::h98c7274e7cb1d11d
  26:     0x7f349819bf0b - std::panicking::try::do_call::h99ed0da044e497c3
  27:     0x7f3497ed0f16 - __rust_maybe_catch_panic
  28:     0x7f34981ba461 - <F as alloc::boxed::FnBox<A>>::call_box::hbdd5a14cd8e33b97
  29:     0x7f3497ec4ef0 - std::sys::thread::Thread::new::thread_start::h50b05608a499d2b2
  30:     0x7f34901c0483 - start_thread
  31:     0x7f3497b916dc - clone
  32:                0x0 - <unknown>

[TimNN]

Regression from 1.11 to 1.12.

[alexcrichton]

cc @rust-lang/compiler, another stable-to-stable regression :(

[nikomatsakis]

Pending fix in #37110

[brson]

There is a PR open to solve this in a different way.