task 'rustc' failed at 'index out of bounds: the len is 12 but the index is 12'

[tshepang]

I got this code, a simplified form of what I saw in the Guide (section Testing):

fn three_times_four() -> int { 3 * 4 }

#[test]
fn test_1() {
    assert_eq!(12, three_times_four());
}

#[cfg(test)]
mod test {
    use super::three_times_four;

    #[test]
    fn test_2() {
        assert!(12, three_times_four())
    }
}

And running it:

$ rustc --version
rustc 0.12.0-pre (471862f40 2014-08-24 09:30:56 +0000)
$ uname --all
Linux thome 3.15-trunk-amd64 #1 SMP Debian 3.15.1-1~exp1 (2014-06-20) x86_64 GNU/Linux
$ RUST_BACKTRACE=1 rustc --test main.rs
<std macros>:8:12: 14:19 error: mismatched types: expected `bool` but found `<generic integer #0>` (expected bool but found integral variable)
<std macros>:8         if !$cond {
<std macros>:9             fail!($($arg),+)
<std macros>:10         }
<std macros>:11     );
<std macros>:12 )
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 12 but the index is 12', /home/tshepang/projects/rust/src/libsyntax/lib.rs:1

stack backtrace:
   1:     0x7f0cb4473480 - rt::backtrace::imp::write::h235035dd269e20b4UYq
   2:     0x7f0cb4476630 - failure::on_fail::hd1a7e992688ab3ceBkr
   3:     0x7f0cb8a28e40 - unwind::begin_unwind_inner::hb4c6bf8d66435096pie
   4:     0x7f0cb8a28b40 - unwind::begin_unwind_fmt::h86f5356db6ec628ePfe
   5:     0x7f0cb8a28b00 - rust_begin_unwind
   6:     0x7f0cb8a77800 - failure::begin_unwind::h7b5a533fc9421dfbnAk
   7:     0x7f0cb8a7a7c0 - failure::fail_bounds_check::h2e800593d4e78a44zyk
   8:     0x7f0cb758dee0 - codemap::FileMap::get_line::hddd51750c3eea6b5EyE
   9:     0x7f0cb7597f50 - diagnostic::emit::h17d12cac27463098tVF
  10:     0x7f0cb7594e70 - diagnostic::EmitterWriter.Emitter::emit::h072471d33cf09c1a0QF
  11:     0x7f0cb75931f0 - diagnostic::Handler::emit::h5ef2540673a3b36epyF
  12:     0x7f0cb758cae0 - diagnostic::SpanHandler::span_err::haa1d6440e60b94bbEmF
  13:     0x7f0cb9593990 - middle::typeck::infer::InferCtxt<'a>::type_error_message_str_with_expected::hecddb89bcc2602a1Pdc
  14:     0x7f0cb9632e50 - middle::typeck::infer::InferCtxt<'a>::type_error_message::h82a8041df2114fa6glc
  15:     0x7f0cb9633060 - middle::typeck::infer::InferCtxt<'a>::report_mismatched_types::he1a60d697010400emmc
  16:     0x7f0cb95e6580 - middle::typeck::check::demand::suptype::closure.122490
  17:     0x7f0cb95e6490 - middle::typeck::check::demand::suptype_with_fn::h36e7cd05f630094aISO
  18:     0x7f0cb9642be0 - middle::typeck::check::check_expr_has_type::closure.123466
  19:     0x7f0cb9637df0 - middle::typeck::check::check_expr_with_unifier::h532c026a98936bd1cxU
  20:     0x7f0cb9637df0 - middle::typeck::check::check_expr_with_unifier::h532c026a98936bd1cxU
  21:     0x7f0cb9604850 - middle::typeck::check::check_block_with_expected::hcc1fb6e3f987aab0VFW
  22:     0x7f0cb96009d0 - middle::typeck::check::check_fn::haf17c837a63ca21aYOR
  23:     0x7f0cb96006f0 - middle::typeck::check::check_bare_fn::h1697162caded9650DDR
  24:     0x7f0cb95f98d0 - middle::typeck::check::check_item::h3c5ed16ca47f89b7KbS
  25:     0x7f0cb95fb5d0 - visit::walk_item::h13949830449449897568
  26:     0x7f0cb96004f0 - middle::typeck::check::check_item_types::h86b08addca7a3d44UCR
  27:     0x7f0cb907c880 - util::common::time::h7845477028010386476
  28:     0x7f0cb97de3e0 - middle::typeck::check_crate::hca6bcc1827718082koi
  29:     0x7f0cb98a0660 - driver::driver::phase_3_run_analysis_passes::ha18773997d369cedkSw
  30:     0x7f0cb989b800 - driver::driver::compile_input::h83dff1ab89a68b6eqEw
  31:     0x7f0cb992f8d0 - driver::run_compiler::hf037f9b7b9d7b27ejbA
  32:     0x7f0cb992f7e0 - driver::main_args::closure.137206
  33:     0x7f0cb99416b0 - task::TaskBuilder<S>::try_future::closure.138326
  34:     0x7f0cb99414b0 - task::TaskBuilder<S>::spawn_internal::closure.138303
  35:     0x7f0cb8d91640 - task::spawn_opts::closure.8268
  36:     0x7f0cb8a89d20 - rust_try_inner
  37:     0x7f0cb8a89d10 - rust_try
  38:     0x7f0cb8a264b0 - unwind::try::h4632958e716dfba1F6d
  39:     0x7f0cb8a26250 - task::Task::run::h717f2b1ef13686ffZcd
  40:     0x7f0cb8d91400 - task::spawn_opts::closure.8214
  41:     0x7f0cb8a28090 - thread::thread_start::h8bc121b89a283d9aLBd
  42:     0x7f0cb37f2fe0 - start_thread
  43:     0x7f0cb86f6f89 - __clone
  44:                0x0 - <unknown>

Fixing the typo (assert -> assert_eq) builds without an issue.

[ghost]

Thanks! Looks like a duplicate of #14091.

[tshepang]

It's different code though, but I don't know enough to know if that matters.

[alexcrichton]

Yes, this looks to be a dupe, thanks @jakub-!