MIR panicked compilation

[Songbird0]

Hi there,

Issue #36092 title print this error too, but not for the same reason.
When I run the MIR compilation on play.rust-lang.org, I get an error.
However, I can run the Rust -> Binary compilation without any problem.

I tried this code:

use std::path::*;

fn main()
{
    let mut foo : String = "hello".to_string();
    foo.push(MAIN_SEPARATOR);
    println!("{}", foo);
}

I expected to see this happen: prints "hello/"

Instead, this happened: I get an error

Meta

rustc --version --verbose:

rustc 1.14.0-nightly (cae6ab1c4 2016-11-05)
error: internal compiler error: unexpected panic

Backtrace:

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:     0x7f32e79237fa - std::sys::imp::backtrace::tracing::imp::write::he3d1bfbdbf113480
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:42
   2:     0x7f32e793599f - std::panicking::default_hook::{{closure}}::h575f1b40d2e88f07
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:247
   3:     0x7f32e79321f5 - std::panicking::default_hook::h3d5dccce8125d0cf
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:257
   4:     0x7f32e7932907 - std::panicking::rust_panic_with_hook::h00b81bb3dcbd51f2
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:451
   5:     0x7f32e7932794 - std::panicking::begin_panic::ha6a0d553db9869ff
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:413
   6:     0x7f32e79326b9 - std::panicking::begin_panic_fmt::h24d113aee3ee4081
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:397
   7:     0x7f32e7932647 - rust_begin_unwind
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:373
   8:     0x7f32e798384d - core::panicking::panic_fmt::he441b2ea2036b98a
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libcore/panicking.rs:69
   9:     0x7f32e7983784 - core::panicking::panic::haf296e94ad32f436
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libcore/panicking.rs:49
  10:     0x7f32e7cf8de6 - rustc_driver::pretty::print_with_analysis::{{closure}}::h2fc26bd99115e425
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libcore/macros.rs:21
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_mir/pretty.rs:107
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/pretty.rs:973
  11:     0x7f32e7cf3e73 - rustc_driver::driver::phase_3_run_analysis_passes::{{closure}}::h66f9e9eb1b5f338b
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/driver.rs:979
  12:     0x7f32e7cb891f - rustc_driver::driver::phase_3_run_analysis_passes::h1111b274931d7851
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc/ty/context.rs:966
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/local.rs:245
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc/ty/context.rs:963
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc/ty/context.rs:950
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/local.rs:245
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc/ty/context.rs:947
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc/ty/context.rs:735
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/driver.rs:854
  13:     0x7f32e7ccb851 - rustc_driver::pretty::print_after_hir_lowering::had0aca66ce21139b
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/pretty.rs:954
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/pretty.rs:833
  14:     0x7f32e7cfacce - <rustc_driver::RustcDefaultCalls as rustc_driver::CompilerCalls<'a>>::build_controller::{{closure}}::h863cbb343cab38f2
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/lib.rs:487
  15:     0x7f32e7ca5b6d - rustc_driver::driver::compile_input::h21840cdf516c3ab1
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/driver.rs:144
  16:     0x7f32e7cd06a0 - rustc_driver::run_compiler::h81a62653df4e7b03
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/lib.rs:222
  17:     0x7f32e7c0fbd8 - std::panicking::try::do_call::h54deb93462da3a7f
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/lib.rs:1138
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/lib.rs:138
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/librustc_driver/lib.rs:1072
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:295
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:356
  18:     0x7f32e793d8aa - __rust_maybe_catch_panic
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libpanic_unwind/lib.rs:97
  19:     0x7f32e7c2e568 - <F as alloc::boxed::FnBox<A>>::call_box::h2181ecf694b72547
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panicking.rs:332
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/panic.rs:351
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/thread/mod.rs:287
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/liballoc/boxed.rs:595
  20:     0x7f32e79314c4 - std::sys::imp::thread::Thread::new::thread_start::h990fb082eb5abe34
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/liballoc/boxed.rs:605
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/sys_common/thread.rs:21
                        at /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/obj/../src/libstd/sys/unix/thread.rs:84
  21:     0x7f32dfbef709 - start_thread
  22:     0x7f32e75ec82c - clone
  23:                0x0 - <unknown>

Thanks for your reading.

[TimNN]

(To reproduce locally run with --unpretty mir -Z unstable-options).

[TimNN]

Introduced between nightly-2016-10-28 and nightly-2016-11-02 (Changes).

[Mark-Simulacrum]

Marking as E-needstest, doesn't reproduce today.