ICE when compiling a package

[goddessfreya]

The compiler panics.

I tried this code:
https://github.com/XavilPergis/birblike

I expected to see this happen: The program compiling or giving an error.

Instead, this happened: The program paniced

Meta

rustc --version --verbose:

rustc 1.28.0-nightly (01cc982e9 2018-06-24)
binary: rustc
commit-hash: 01cc982e936120acb0424e41de14e42ba2d88c6f
commit-date: 2018-06-24
host: x86_64-unknown-linux-gnu
release: 1.28.0-nightly
LLVM version: 6.0

Backtrace:

stack backtrace:
   0:     0x563761a8ce5c - backtrace::backtrace::trace::h472e449cde1c6db8
   1:     0x563761a8b842 - backtrace::capture::Backtrace::new_unresolved::ha5d86bb667abb4d6
   2:     0x563761a8b4b2 - failure::backtrace::internal::InternalBacktrace::new::h5aacf1ab9379901b
   3:     0x563761a8af11 - <failure::backtrace::Backtrace as core::default::Default>::default::h3338d50a42bee772
   4:     0x563761a8af68 - failure::backtrace::Backtrace::new::hd9cc93bbf7427c49
   5:     0x56376160f66a - cargo::util::process_builder::ProcessBuilder::exec::hd51ef9b28c6bd41a
   6:     0x5637617186bf - cargo::core::compiler::Executor::exec::hc21f154f92a53265
   7:     0x563761710796 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::hece56ccf2a0ff770
   8:     0x5637616722f0 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::h7da33457f01d1a28
   9:     0x5637616722f0 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::h7da33457f01d1a28
  10:     0x56376167291b - cargo::core::compiler::job::Job::run::hf433aeb4ba83654f
  11:     0x5637616a03af - <F as crossbeam::FnBox>::call_box::ha53148e1d0135323
  12:     0x563761c82bb9 - __rust_maybe_catch_panic
                        at libpanic_unwind/lib.rs:105
  13:     0x5637615fdc49 - <F as alloc::boxed::FnBox<A>>::call_box::h98611f1a55834dbf
  14:     0x563761c6f2da - <alloc::boxed::Box<alloc::boxed::FnBox<A, Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$::call_once::hbf81ad29f57ceb92
                        at /checkout/src/liballoc/boxed.rs:650
                         - std::sys_common::thread::start_thread::h9f808e1cb13674ec
                        at libstd/sys_common/thread.rs:24
  15:     0x563761c5c6e5 - std::sys::unix::thread::Thread::new::thread_start::h668a95d388fe6493
                        at libstd/sys/unix/thread.rs:90
  16:     0x7f73a1227074 - start_thread
  17:     0x7f73a0d4053e - clone
  18:                0x0 - <unknown>

stack backtrace:
   0:     0x563761a8ce5c - backtrace::backtrace::trace::h472e449cde1c6db8
   1:     0x563761a8b842 - backtrace::capture::Backtrace::new_unresolved::ha5d86bb667abb4d6
   2:     0x563761a8b4b2 - failure::backtrace::internal::InternalBacktrace::new::h5aacf1ab9379901b
   3:     0x563761a8af11 - <failure::backtrace::Backtrace as core::default::Default>::default::h3338d50a42bee772
   4:     0x563761a8af68 - failure::backtrace::Backtrace::new::hd9cc93bbf7427c49
   5:     0x5637616c8008 - <core::result::Result<T, E> as cargo::util::errors::CargoResultExt<T, E>>::chain_err::h5438d11452f469cd
   6:     0x5637617107b3 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::hece56ccf2a0ff770
   7:     0x5637616722f0 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::h7da33457f01d1a28
   8:     0x5637616722f0 - <F as cargo::core::compiler::job::FnBox<A, R>>::call_box::h7da33457f01d1a28
   9:     0x56376167291b - cargo::core::compiler::job::Job::run::hf433aeb4ba83654f
  10:     0x5637616a03af - <F as crossbeam::FnBox>::call_box::ha53148e1d0135323
  11:     0x563761c82bb9 - __rust_maybe_catch_panic
                        at libpanic_unwind/lib.rs:105
  12:     0x5637615fdc49 - <F as alloc::boxed::FnBox<A>>::call_box::h98611f1a55834dbf
  13:     0x563761c6f2da - <alloc::boxed::Box<alloc::boxed::FnBox<A, Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$::call_once::hbf81ad29f57ceb92
                        at /checkout/src/liballoc/boxed.rs:650
                         - std::sys_common::thread::start_thread::h9f808e1cb13674ec
                        at libstd/sys_common/thread.rs:24
  14:     0x563761c5c6e5 - std::sys::unix::thread::Thread::new::thread_start::h668a95d388fe6493
                        at libstd/sys/unix/thread.rs:90
  15:     0x7f73a1227074 - start_thread
  16:     0x7f73a0d4053e - clone
  17:                0x0 - <unknown>
`

[goddessfreya]

Full info attached
log.zip

[jonas-schievink]

This builds fine on the current nightly. Getting a test case might be difficult though.

[rossmacarthur]

Reduced to

#![feature(nll)]

use std::ops::Index;

pub struct Test<T> {
    a: T,
}

impl<T> Index<usize> for Test<T> {
    type Output = T;

    fn index(&self, _index: usize) -> &Self::Output {
        &self.a
    }
}

fn main() {}

This fails with the identical error

$ RUSTUP_TOOLCHAIN=nightly-2018-06-24 rustc issue-51770.rs
thread 'main' panicked at 'region_obligations not empty: [
    (
        NodeId(
            23
        ),
        RegionObligation(sub_region='_#1r, sup_type=T)
    )
]', librustc/infer/mod.rs:1057:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.

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: rustc 1.28.0-nightly (60efbdead 2018-06-23) running on x86_64-apple-darwin

Submitting a PR now with this as a test.