task 'rustc' failed at 'index out of bounds: the len is 0 but the index is 0

[Nullreff]

The Rust compiler displays the following error when building my project. I'm running 32bit Debian Stable.

> rustc --version
rustc 0.12.0-pre-nightly (325808a33 2014-09-08 20:51:14 +0000)

> RUST_BACKTRACE=1 rustc rustymine.rs 
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'index out of bounds: the len is 0 but the index is 0', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/librustc/middle/check_match.rs:524

stack backtrace:
   1: 0xb5fcb7e0 - rt::backtrace::imp::write::h3a47248f3065eac3F8q
   2: 0xb5fce720 - failure::on_fail::hdbacec6aadb65e07nur
   3: 0xb633ad50 - unwind::begin_unwind_inner::h5300f193b285b88962d
   4: 0xb633a940 - unwind::begin_unwind_fmt::h7172303ea891f784q0d
   5: 0xb633a8e0 - rust_begin_unwind
   6: 0xb6386b90 - failure::begin_unwind::h655f95ed1bb60961Wnk
   7: 0xb6386a10 - failure::fail_bounds_check::h20dabaa82101fe44Skk
   8: 0xb67360b0 - middle::check_match::is_useful::h9e3b962eb29b67abC7n
   9: 0xb674ecb0 - middle::check_match::is_useful_specialized::hfe48f6eb9f7260ccygo
  10: 0xb674e1d0 - middle::check_match::is_useful::closure.115587
  11: 0xb67360b0 - middle::check_match::is_useful::h9e3b962eb29b67abC7n
  12: 0xb674ecb0 - middle::check_match::is_useful_specialized::hfe48f6eb9f7260ccygo
  13: 0xb674e1d0 - middle::check_match::is_useful::closure.115587
  14: 0xb67360b0 - middle::check_match::is_useful::h9e3b962eb29b67abC7n
  15: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  16: 0xb6733c90 - visit::walk_block::h2389838162361242636
  17: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  18: 0xb6733c90 - visit::walk_block::h2389838162361242636
  19: 0xb6731c60 - middle::check_match::check_fn::he2b12c28d6b0f26f2Fo
  20: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  21: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  22: 0xb6733c90 - visit::walk_block::h2389838162361242636
  23: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  24: 0xb6733c90 - visit::walk_block::h2389838162361242636
  25: 0xb6731c60 - middle::check_match::check_fn::he2b12c28d6b0f26f2Fo
  26: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  27: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  28: 0xb6733c90 - visit::walk_block::h2389838162361242636
  29: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  30: 0xb6733c90 - visit::walk_block::h2389838162361242636
  31: 0xb6731c60 - middle::check_match::check_fn::he2b12c28d6b0f26f2Fo
  32: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  33: 0xb672d580 - middle::check_match::check_expr::h72f8cc5487eaaabcwvn
  34: 0xb6733c90 - visit::walk_block::h2389838162361242636
  35: 0xb6731c60 - middle::check_match::check_fn::he2b12c28d6b0f26f2Fo
  36: 0xb67339b0 - visit::walk_method_helper::h1060611821396196880
  37: 0xb6732c10 - visit::walk_item::h7664931802223527900
  38: 0xb6732280 - middle::check_match::check_crate::h5b27abcac0ce801d1un
  39: 0xb6e2b490 - driver::driver::phase_3_run_analysis_passes::closure.147043
  40: 0xb64f2990 - util::common::time::h812626770107026942
  41: 0xb6dc3b20 - driver::driver::phase_3_run_analysis_passes::hb99188760c9b77156YD
  42: 0xb6dbf360 - driver::driver::compile_input::hd4ea02dac05db950JKD
  43: 0xb6e51d60 - driver::run_compiler::he2e446b60ce2ccb41CH
  44: 0xb6e51c50 - driver::main_args::closure.148066
  45: 0xb650a4d0 - task::TaskBuilder<S>::try_future::closure.100101
  46: 0xb650a2d0 - task::TaskBuilder<S>::spawn_internal::closure.100072
  47: 0xb76d6ed0 - task::spawn_opts::closure.8393
  48: 0xb633a700 - unwind::try::try_fn::hdf9b81d28426036bETd
  49: 0xb6396da0 - rust_try_inner
  50: 0xb6396d60 - rust_try
  51: 0xb63385d0 - unwind::try::hae97d74b77b782e2gRd
  52: 0xb6338420 - task::Task::run::h92279797e7a5a13d92c
  53: 0xb76d6c80 - task::spawn_opts::closure.8333
  54: 0xb6339ec0 - thread::thread_start::he3aa271ed21f4438god
  55:        0x0 - <unknown>

[mdinger]

Reduced:

use std::io::{IoError, InvalidInput};
use std::io::net::tcp::TcpStream;

enum Packet {JsonPacket(u8, str)}

impl Packet {
    fn read_json(stream: &mut TcpStream) {
        Ok(0u).and_then(|size| {
            stream.read_byte().and_then(|command| {
                stream.read_exact(size - 1).and_then(|data| {
                    match std::str::from_utf8(data.as_slice()) {
                        Some(&json) => Ok(JsonPacket(command, json)),
                        None => Err(IoError {
                            kind: InvalidInput,
                            desc: "hi",
                            detail: None
                        })
                    }
                })
            })
        });
    }
}

fn main() {}

[mdinger]

@eddyb says it reduces to this:

Min:

fn main() {
    let &x = "foo";
}

Also says it's probably the same as this: #17118 (comment)

[Nullreff]

This has been fixed on master.