Rust panic at assertion in latest nightly

[obsgolem]

I am consistently getting a panic when compiling a particular project. It does not appear to occur when compiling one of libraries that project depends on: https://github.com/retep998/winapi-rs. The project being compiled is a library. The panic appears to chronologically occur after the compiler generates dead code warnings. Here is my backtrace:

Compiling win32_experiment v0.0.1 (file:///PATH_HERE)
thread 'rustc' panicked at 'assertion failed: f.abi == Rust || f.abi == RustCall', C:\bot\slave\nightly-dist-rustc-win-64\build\src\librustc_trans\trans\base.rs:2418

stack backtrace:
   1:         0x69bee9cd - sys::backtrace::write::hd40c6de25ef01e0bfjt
   2:         0x69c01a32 - rt::unwind::register::hcb202fda23aef97aw7y
   3:         0x69b834a7 - rt::unwind::begin_unwind_inner::h43ca250f1ae88b3e64y
   4:          0x1423d4c - trans::context::CrateContext<'b, 'tcx>::link_meta::ha7fe491c1a9e61d23qm
   5:          0x1540ee7 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::hc8a6918f1c87a4b9ngK
   6:          0x1542dce - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::hc8a6918f1c87a4b9ngK
   7:          0x145dcad - trans::context::CrateContext<'b, 'tcx>::sess::h0c92734bae2bfb65wmm
   8:          0x145c390 - trans::context::CrateContext<'b, 'tcx>::stats::hfdf50b198e5f7592qzm
   9:          0x153fc48 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::hc8a6918f1c87a4b9ngK
  10:          0x145b857 - trans::context::CrateContext<'b, 'tcx>::stats::hfdf50b198e5f7592qzm
  11:          0x1544728 - trans::base::trans_crate::ha9ad2d2ee040c191Udv
  12:         0x70b2543a - driver::phase_4_translate_to_llvm::h9dcbc7c0b9c8c65bJFa
  13:         0x70b03243 - driver::compile_input::h45b30318e07c4cf6vba
  14:         0x70bcaa1e - run::heefafb1ff7869308B4b
  15:         0x70bc786a - run::heefafb1ff7869308B4b
  16:         0x69c288fc - rust_try
  17:         0x69c288d9 - rust_try
  18:         0x70bc7fa9 - run::heefafb1ff7869308B4b
  19:         0x69bf3457 - sys::tcp::TcpListener::bind::hfcf283b88d14d24bfTv
  20:     0x7ffd5c43a6e2 - BaseThreadInitThunk

This is the output of rustc --version --verbose

rustc 1.0.0-nightly (ea6f65c5f 2015-01-06 19:47:08 +0000)
binary: rustc
commit-hash: ea6f65c5f1a3f84e010d2cef02a0160804e9567a
commit-date: 2015-01-06 19:47:08 +0000
host: x86_64-pc-windows-gnu
release: 1.0.0-nightly

[obsgolem]

Still occurring in rustc 1.0.0-nightly (44a287e6e 2015-01-08 17:03:40 -0800).

[obsgolem]

I have found the cause of the panic. If you try to define an extern "system" function in the impl of a struct the compiler panics. This is the code used to reproduce the bug:

struct A;
impl A {
    extern "system" fn a() {
        println!("this does not compile");
    }
}

fn main() {
    println!("doesn't work in binaries");
}

This is the backtrace on the latest nightly 44a287e:

thread 'rustc' panicked at 'assertion failed: f.abi == Rust || f.abi == RustCall', C:\bot\slave\nightly-dist-rustc-win-64\build\src\librustc_trans\trans\base.rs:2438

stack backtrace:
   1:         0x69bec997 - sys::backtrace::write::h62d87c63e18a3ea5JRt
   2:         0x69c00672 - rt::unwind::register::haa3a38fa07bfa9beVGz
   3:         0x69b834a7 - rt::unwind::begin_unwind_inner::hbebf9f8c0125ffc9tEz
   4:          0x1473bac - trans::context::CrateContext<'b, 'tcx>::link_meta::h9c4774348aced35ahym
   5:          0x158fe67 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::h2dd10ee030f9c94e6DK
   6:          0x1591bce - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::h2dd10ee030f9c94e6DK
   7:          0x14ac310 - trans::context::CrateContext<'b, 'tcx>::sess::h6fdd1e7dea5490cdItm
   8:          0x14aa9a2 - trans::context::CrateContext<'b, 'tcx>::stats::hd7a1dc7a2465d605EGm
   9:          0x1593768 - trans::base::trans_crate::h4bc502f506e6c118Wsv
  10:         0x70b2af6a - driver::phase_4_translate_to_llvm::haa9c5e826483e242PFa
  11:         0x70b03623 - driver::compile_input::hf5b2f58693da03b5xba
  12:         0x70bd1eec - run::ha65e56249318cc0dV3b
  13:         0x70bd04cc - run::ha65e56249318cc0dV3b
  14:         0x70bcf16a - run::ha65e56249318cc0dV3b
  15:         0x69c2881c - rust_try
  16:         0x69c287f9 - rust_try
  17:         0x70bcf854 - run::ha65e56249318cc0dV3b
  18:         0x69bf14a7 - sys::tcp::TcpListener::bind::hc4a8da4adad0f541bsw
  19:     0x7ffd5c43a6e2 - BaseThreadInitThunk

[Gankra]

Still occuring.