ICE: unimplemented foreign functions with Rust ABI

[mark3982]

error: internal compiler error: unimplemented foreign functions with Rust ABI
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>', /mnt/host/kmcg3413.net/rust/src/libsyntax/diagnostic.rs:189

stack backtrace:
   1:     0x7f614b4d6772 - sys::backtrace::write::hf2cbe7ef4486b86aIDA
   2:     0x7f614b4fc7f2 - panicking::on_panic::he84feb8369199f6ebJJ
   3:     0x7f614b442e59 - rt::unwind::begin_unwind_inner::h23c9613fd5cda727epJ
   4:     0x7f6148a7acbd - rt::unwind::begin_unwind::h15201399472590650528
   5:     0x7f6148a7b4f5 - diagnostic::Handler::bug::he54a8ae8f22ddcc8GdE
   6:     0x7f6148a7b5c4 - diagnostic::Handler::unimpl::ha56677ddd99e28b6leE
   7:     0x7f61497003bb - session::Session::unimpl::h68e50f0bb54be78frZp
   8:     0x7f614acaddcb - trans::foreign::llvm_calling_convention::h44561cf6ae228910QNA
   9:     0x7f614ac6052b - trans::foreign::register_foreign_item_fn::h16acdaac87c5cffaARA
  10:     0x7f614ab9d69c - trans::base::get_item_val::h954ded8ff9256432ctu
  11:     0x7f614abd67f7 - trans::callee::trans_fn_ref_with_substs::hb375d83ac616a594ong
  12:     0x7f614abd52a9 - trans::callee::trans_fn_ref::hbd5a38063ce6f684Ybg
  13:     0x7f614abd32b2 - trans::callee::trans::h391e2ad0af4ecbdcf1f
  14:     0x7f614abe6282 - trans::callee::trans_call_inner::h3254752094884955895
  15:     0x7f614abeffb7 - trans::expr::trans_rvalue_dps_unadjusted::hef8dfca3ed40ae1ayCi
  16:     0x7f614abaeb16 - trans::expr::trans_into::hfd1d86829031637bTph
  17:     0x7f614abade9e - trans::controlflow::trans_stmt_semi::h55989b37a84cb9a5I6d
  18:     0x7f614abaf56d - trans::controlflow::trans_block::h256c6adade2f2b19v7d
  19:     0x7f614abef5ca - trans::expr::trans_rvalue_dps_unadjusted::hef8dfca3ed40ae1ayCi
  20:     0x7f614abaeb16 - trans::expr::trans_into::hfd1d86829031637bTph
  21:     0x7f614abaf8c7 - trans::controlflow::trans_block::h256c6adade2f2b19v7d
  22:     0x7f614ac6b430 - trans::base::trans_closure::he79ea7f539d044908ot
  23:     0x7f614ab9ee8b - trans::base::trans_fn::hf8ffda1f6e15e21f1zt
  24:     0x7f614ab9ae36 - trans::base::trans_item::h1e743d406713e7f3TXt
  25:     0x7f614ab9afbc - trans::base::trans_item::h1e743d406713e7f3TXt
  26:     0x7f614ac71bdc - trans::base::trans_crate::h36583585edaa27744Tu
  27:     0x7f614bafb292 - driver::phase_4_translate_to_llvm::hcd9743fc2b81ca5dgOa
  28:     0x7f614bad6c8a - driver::compile_input::ha2891122eb1a39f0Nba
  29:     0x7f614bb9b31d - run_compiler::hc4e992049010d432N6b
  30:     0x7f614bb9908c - thunk::F.Invoke<A, R>::invoke::h14385132183911481449
  31:     0x7f614bb97ce0 - rt::unwind::try::try_fn::h10665785272209311867
  32:     0x7f614b5687b8 - rust_try_inner
  33:     0x7f614b5687a5 - rust_try
  34:     0x7f614bb9846b - thunk::F.Invoke<A, R>::invoke::h8207817643633544688
  35:     0x7f614b4e9ff5 - sys::thread::thread_start::hd01357c835e1f75claF
  36:     0x7f6145699b4f - start_thread
  37:     0x7f614b0ce7bc - <unknown>

rustc 1.0.0-dev (6048ba8a5 2015-03-10) (built 2015-03-11)

[frewsxcv]

Is there code we can compile to try and reproduce/debug this error?

[mitaa]

extern "Rust" {
    fn foo();
}

fn main() {
    unsafe { foo() };
}

error: internal compiler error: unimplemented foreign functions with Rust ABI
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/libsyntax/diagnostic.rs:253


playpen: application terminated with error code 101

[randomPoison]

I ran into this issue when I did have the symbol defined, something like:

pub fn foo() {}

mod bar {
    extern "Rust" {
        fn foo();
    }

    pub fn bar() {
        foo();
    }
}

I would have expected this to work, though at least it shouldn't hit an ICE.

[steveklabnik]

Triage: tracked by glacier. no change.

[Mark-Simulacrum]

Neither example ICEs today; not sure why glacier didn't catch this... I believe this is statically impossible today; closing.