ICE when compiling lewton

[est31]

When on latest rust nightly f09420685 2016-10-20, you get an ICE when compiling lewton.

error: internal compiler error: unexpected panic

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 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:323
stack backtrace:
   1:     0x7f78233a903f - std::sys::backtrace::tracing::imp::write::h22f199c1dbb72ba2
   2:     0x7f78233b859d - std::panicking::default_hook::{{closure}}::h9a389c462b6a22dd
   3:     0x7f78233b59c6 - std::panicking::default_hook::h852b4223c1c00c59
   4:     0x7f78233b60a8 - std::panicking::rust_panic_with_hook::hcd9d05f53fa0dafc
   5:     0x7f78233b5f42 - std::panicking::begin_panic::hf6c488cee66e7f17
   6:     0x7f78233b5e80 - std::panicking::begin_panic_fmt::hb0a7126ee57cdd27
   7:     0x7f78233b5e01 - rust_begin_unwind
   8:     0x7f7823403f8f - core::panicking::panic_fmt::h9af671b78898cdba
   9:     0x7f7823403ebb - core::panicking::panic::h1a2d1a6b50eaa468
  10:     0x7f782299f63e - rustc_resolve::Resolver::resolve_module_path::he3d58c7c2b3cede9
  11:     0x7f78229a9439 - rustc_resolve::Resolver::resolve_path::h50912d8fbfa6340b
  12:     0x7f78229a8de8 - rustc_resolve::Resolver::resolve_possibly_assoc_item::h1e6fba50a34943a3
  13:     0x7f78229b2f5d - rustc_resolve::Resolver::resolve_pattern::{{closure}}::h4de63490e31f16d0
  14:     0x7f7822976efa - syntax::ast::Pat::walk::h007eb000795b4942
  15:     0x7f78229a65dd - rustc_resolve::Resolver::resolve_arm::hc9823a8a0b793db7
  16:     0x7f782297f61e - syntax::visit::walk_expr::hd41dc9e4032721dc
  17:     0x7f78229ae028 - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  18:     0x7f78229a6373 - rustc_resolve::Resolver::resolve_local::h3c12c3dc9f1be5bd
  19:     0x7f78229a74cc - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  20:     0x7f78229ac7b5 - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  21:     0x7f78229a74b5 - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  22:     0x7f782297f585 - syntax::visit::walk_expr::hd41dc9e4032721dc
  23:     0x7f78229ae028 - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  24:     0x7f78229a74b5 - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  25:     0x7f78229ae028 - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  26:     0x7f78229a74b5 - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  27:     0x7f78229ac7b5 - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  28:     0x7f78229a74b5 - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  29:     0x7f78229ac07c - rustc_resolve::Resolver::resolve_expr::hcad9be65fa81ebaf
  30:     0x7f78229a74b5 - rustc_resolve::Resolver::resolve_block::h4374c692a6acfefb
  31:     0x7f78229a39bd - rustc_resolve::Resolver::resolve_function::ha0d1c19ce80ef5b9
  32:     0x7f782297f8bf - syntax::visit::walk_item::h395ea077a40162c7
  33:     0x7f78229a0b50 - rustc_resolve::Resolver::resolve_item::hcc157cba4cb08939
  34:     0x7f782297f8ef - syntax::visit::walk_item::h395ea077a40162c7
  35:     0x7f782299fb2d - rustc_resolve::Resolver::resolve_item::hcc157cba4cb08939
  36:     0x7f782299b6ff - rustc_resolve::Resolver::resolve_crate::h611e363ca5034f18
  37:     0x7f78237751ba - rustc_driver::driver::phase_2_configure_and_expand::{{closure}}::hce8b4e82876f8500
  38:     0x7f78237297cb - rustc_driver::driver::phase_2_configure_and_expand::h04526112c643cb41
  39:     0x7f78237210b1 - rustc_driver::driver::compile_input::h5b63ccd49eeeb98b
  40:     0x7f782374e1da - rustc_driver::run_compiler::h98c7274e7cb1d11d
  41:     0x7f782368ae0b - std::panicking::try::do_call::h99ed0da044e497c3
  42:     0x7f78233c0496 - __rust_maybe_catch_panic
  43:     0x7f78236a8951 - <F as alloc::boxed::FnBox<A>>::call_box::hbdd5a14cd8e33b97
  44:     0x7f78233b4420 - std::sys::thread::Thread::new::thread_start::h50b05608a499d2b2
  45:     0x7f781b673709 - start_thread
  46:     0x7f782307b0ae - __clone
  47:                0x0 - <unknown>

error: Could not compile `lewton`.

To learn more, run the command again with --verbose.

[est31]

Its a pretty recent regression, it can't be reproduced with 16eeeac78 2016-10-18.

[est31]

Okay, managed to minimize it:

macro_rules! eno {
    ($expr:expr) => (match $expr {
        $crate::std::result::Result::Ok(val) => (),
        $crate::std::result::Result::Err(_) => (),
    })
}
eno!(Ok(()));

Looks like a regression of #37213.

cc @jseyfried any ideas on this?

[jseyfried]

@est31 Yeah, this was caused by an oversight in #37213 -- fixed in #37361.