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

I'm working through the tutorial, and managed to get a compilation error.

Tested with 0.11.0-pre-nightly (f8c9aec 2014-06-19 05:21:16 +0000) and rustc 0.11.0-pre (a490871a6c3fae9017a6402fcf911d05dcf1d013 2014-06-29 21:41:45 +0000)

OS is Manjaro Linux 64bit

enum List<T> {
    Cons(T, Box<List<T>>),
    Nil
}

fn main() {

    let xs = Cons(5, box Cons(10, box Nil));
    let ys = Cons(5, box Cons(10, box Nil));

    // The methods below are part of the PartialEq trait,
    // which we implemented on our linked list.
    assert!(xs,eq(&ys));

}

fn eq<T: PartialEq> (xs:&List<T>, ys: &List<T>) -> bool {
    // Match on the next node in both lists.
    match (xs, ys) {
        // If we have reached the end of both lists, they are equal.
        (&Nil, &Nil) => true,
        // If the current elements of both lists are equal, keep going.
        (&Cons(ref x, box ref next_xs), &Cons(ref y, box ref next_ys))
            if x == y => eq(next_xs, next_ys),
        // If the current elements are not equal, the lists are not equal.
        _ => false
    }
}

<std macros>:8:12: 13:15 error: cannot apply unary operator `!` to type `List<<generic integer #1>>`
<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/kingsley/Projects/Repositories/rust/src/libsyntax/lib.rs:1

stack backtrace:
   1:     0x7fa6197c8e60 - rt::backtrace::imp::write::h416f5febecf481e0UGp::v0.11.0.pre
   2:     0x7fa6197cf990 - failure::on_fail::hd9dabba9151477e991p::v0.11.0.pre
   3:     0x7fa61b918b10 - unwind::begin_unwind_inner::h48ee93a0d7f13eaccZd::v0.11.0.pre
   4:     0x7fa61b9185c0 - unwind::begin_unwind_fmt::h6e98fd5ad319e451FWd::v0.11.0.pre
   5:     0x7fa61b918580 - rust_begin_unwind
   6:     0x7fa61b9632c0 - failure::begin_unwind::hee56801fc34bd58cX2v::v0.11.0.pre
   7:     0x7fa61b964cd0 - failure::fail_bounds_check::h2c22b5b93c6cdf7090v::v0.11.0.pre
   8:     0x7fa61ad6e9a0 - codemap::FileMap::get_line::ha6ed00e959e41056RDd::v0.11.0.pre
   9:     0x7fa61ad6a410 - diagnostic::emit::h93a2a5b799d5960c0uc::v0.11.0.pre
  10:     0x7fa61ad656b0 - diagnostic::EmitterWriter.Emitter::emit::haaf5e62e051041109qc::v0.11.0.pre
  11:     0x7fa61ad63c40 - diagnostic::Handler::emit::he4f3014008107a63kec::v0.11.0.pre
  12:     0x7fa61ad62f10 - diagnostic::SpanHandler::span_err::h7b21ffeef41be1b3Q4b::v0.11.0.pre
  13:     0x7fa61c519350 - middle::typeck::infer::InferCtxt<'a>::type_error_message_str_with_expected::h34f02c25bcd032bd6Kw::v0.11.0.pre
  14:     0x7fa61c5c9810 - middle::typeck::infer::InferCtxt<'a>::type_error_message::hdf83fa3337b86f10OSw::v0.11.0.pre
  15:     0x7fa61c5d7cc0 - middle::typeck::check::check_expr_with_unifier::check_user_unop::closure.92651
  16:     0x7fa61c5d5450 - middle::typeck::check::check_expr_with_unifier::lookup_op_method::he5adda6db52a2c77SFf::v0.11.0.pre
  17:     0x7fa61c5d7950 - middle::typeck::check::check_expr_with_unifier::check_user_unop::h2b1f451b9b0268c8HUf::v0.11.0.pre
  18:     0x7fa61c5cd4c0 - middle::typeck::check::check_expr_with_unifier::hbb12d5ac9878a1467rf::v0.11.0.pre
  19:     0x7fa61c5cd4c0 - middle::typeck::check::check_expr_with_unifier::hbb12d5ac9878a1467rf::v0.11.0.pre
  20:     0x7fa61c5e8ce0 - middle::typeck::check::check_stmt::h616240c5bb924a2f1ih::v0.11.0.pre
  21:     0x7fa61c5a2f70 - middle::typeck::check::check_block_with_expected::hd46188bf10bca4c0cnh::v0.11.0.pre
  22:     0x7fa61c59e670 - middle::typeck::check::check_fn::h6b698d4a809e2272jUc::v0.11.0.pre
  23:     0x7fa61c59e430 - middle::typeck::check::check_bare_fn::h5e40c317ce0ca95bRJc::v0.11.0.pre
  24:     0x7fa61c597e80 - middle::typeck::check::check_item::h42f9fe4be6f302635gd::v0.11.0.pre
  25:     0x7fa61c59e230 - middle::typeck::check::check_item_types::habfcdf0c64ccccdf9Ic::v0.11.0.pre
  26:     0x7fa61c71b810 - middle::typeck::check_crate::h27c2b9882055e043SJC::v0.11.0.pre
  27:     0x7fa61cb93c80 - driver::driver::phase_3_run_analysis_passes::h3d00644185dbaa4f84p::v0.11.0.pre
  28:     0x7fa61cb8f230 - driver::driver::compile_input::h3cdb3a46225f37066Rp::v0.11.0.pre
  29:     0x7fa61cc5bfe0 - driver::run_compiler::h0b665bca7c20427c5Bs::v0.11.0.pre
  30:     0x7fa61cc5bef0 - driver::main_args::closure.117254
  31:     0x7fa61cc71010 - task::TaskBuilder<S>::try_future::closure.118394
  32:     0x7fa61cc70c30 - task::TaskBuilder<S>::spawn_internal::closure.118371
  33:     0x7fa61bc76cc0 - task::spawn_opts::closure.7461
  34:     0x7fa61b979170 - rust_try
  35:     0x7fa61b915120 - unwind::try::hf096e195bac714bbBNd::v0.11.0.pre
  36:     0x7fa61b914e00 - task::Task::run::he089a676a6c62e49XYc::v0.11.0.pre
  37:     0x7fa61bc76a80 - task::spawn_opts::closure.7407
  38:     0x7fa61b9179c0 - thread::thread_start::he5b88e576f787f6dvld::v0.11.0.pre
  39:     0x7fa61923e060 - start_thread
  40:     0x7fa61b5df489 - __clone
  41:                0x0 - <unknown>

[ben0x539]

Can you reproduce this with a more recent rustc build/nightly somehow? It errors properly without an ICE for me.

Sorry for the delay.
I noticed what I pasted wasn't quite right, and I've updated my first post. Same error with latest git version.

[ben0x539]

This is pretty weird, you can remove almost all the code but it's whitespace sensitive. Reproduces for me with no less than 12 blank lines and then one line with just fn main() { assert!((),()); }

[schmee]

Looks like a dupe of #14091.

[alexcrichton]

Closing as a dupe of #14091