ICE with byte char literal in match

[lilyball]

Using a b'x' literal in a match in one arm when another arm uses an integral literal causes an ICE.

Code:

pub fn main() {
    let (a, b) = (1u8, 2u8);

    let _x = match (a, b) {
        (0x1b, b'\\') => 1u,
        (_, 0x05) => 2u,
        _ => 5u
    };
}

Results:

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 'compare_list_exprs: type mismatch', /Volumes/Himling/Users/kevin/Dev/rust/rust/src/librustc/middle/trans/_match.rs:236

stack backtrace:
   1:        0x10b611c19 - rt::backtrace::imp::write::h49e167be6c35c7a6I3q
   2:        0x10b614f71 - failure::on_fail::h2de262f0fa07a6d1mkr
   3:        0x10b89c025 - unwind::begin_unwind_inner::h9dd2b45e3189ab76PQd
   4:        0x10825d84c - unwind::begin_unwind::h17200107724015028583
   5:        0x1086bb033 - middle::trans::_match::Opt<'a>::eq::ha0347177cb74f650KDg
   6:        0x1086c7908 - middle::trans::_match::compile_submatch_continue::h2c95eff2a4dfe45ejHh
   7:        0x1086c42f0 - middle::trans::_match::compile_submatch::he72af60857c57ca2yBh
   8:        0x1086c729f - middle::trans::_match::compile_submatch_continue::h2c95eff2a4dfe45ejHh
   9:        0x1086c42f0 - middle::trans::_match::compile_submatch::he72af60857c57ca2yBh
  10:        0x10864fb8b - middle::trans::_match::trans_match::h01258bca90f67af8E0h
  11:        0x10863cc1c - middle::trans::expr::trans_rvalue_dps_unadjusted::h27302feaf01beb5aZ03
  12:        0x1085fe8ed - middle::trans::expr::trans_into::h148e25892fc50848QC2
  13:        0x1086d76fe - middle::trans::_match::store_local::closure.127410
  14:        0x1086d7565 - middle::trans::_match::mk_binding_alloca::h10952157501536158966
  15:        0x1086a375d - middle::trans::_match::store_local::h4bc417dc83908137Xdi
  16:        0x1085fde6a - middle::trans::base::init_local::hc06087db4c732c66eYd
  17:        0x1085fd331 - middle::trans::controlflow::trans_stmt::h4fb6e8ab2ae05364OEY
  18:        0x1085feb98 - middle::trans::controlflow::trans_block::h4903f12a15b4b417UJY
  19:        0x1086ac572 - middle::trans::base::trans_closure::hcc72f0bf6b75cf89EPe
  20:        0x1085f17f8 - middle::trans::base::trans_fn::h50dd8cb21b7d227f20e
  21:        0x1085eec9a - middle::trans::base::trans_item::h2481520530d8b2c5lkf
  22:        0x1086b5d78 - middle::trans::base::trans_crate::h2d09203b93180fb4Bkg
  23:        0x108abc895 - driver::driver::phase_4_translate_to_llvm::h480b949b4d48af47pJw
  24:        0x108ab5613 - driver::driver::compile_input::h7ecbeb2017ef3606rgw
  25:        0x108b33b34 - driver::run_compiler::ha722889403f0b6bdn6z
  26:        0x108b31d26 - driver::main_args::closure.146118
  27:        0x1082949ab - task::TaskBuilder<S>::try_future::closure.101380
  28:        0x1082948a3 - task::TaskBuilder<S>::spawn_internal::closure.101351
  29:        0x10b4e44bd - task::spawn_opts::closure.8577
  30:        0x10b903ecc - rust_try_inner
  31:        0x10b903eb6 - rust_try
  32:        0x10b899437 - unwind::try::h493476c01d8d39d6xFd
  33:        0x10b8992ac - task::Task::run::hd474352d5be20d9fMVc
  34:        0x10b4e4312 - task::spawn_opts::closure.8516
  35:        0x10b89af6a - thread::thread_start::hf69b37c15c1d48651fd
  36:     0x7fff8d29d2fc - _pthread_body
  37:     0x7fff8d29d279 - _pthread_body

rustc 0.12.0-pre (496b68d48 2014-09-29 01:03:06 +0000)

[lilyball]

Doesn't require byte literals. It just requires two integral literals, one which is known at const-eval time to be unsigned, and one which is unknown (and therefore defaults to signed):

pub fn main() {
    let (a, b) = (1u8, 2u8);

    let _x = match (a, b) {
        (0x1b, 0x01) => 1u,
        (_, 0x05u8) => 2u,
        _ => 5u
    };
}

[lilyball]

Oddly, if I try a simpler version:

pub fn main() {
    match 5u8 {
        1 => (),
        2u8 => (),
        _ => ()
    }
}

I get a type error:

<anon>:3:9: 3:10 error: mismatched types between arms
<anon>:3         1 => (),
                 ^
error: aborting due to previous error

Even though it seems like this should work just fine. I don't know why the previous version works.

[mahkoh]

cc #16745

[steveklabnik]

Triage: I still get an ICE today.

[tamird]

Compiles without issue.

pub fn main() {
    let (a, b) = (1u8, 2u8);

    let _x = match (a, b) {
        (0x1b, b'\\') => 1u8,
        (_, 0x05) => 2u8,
        _ => 5u8,
    };
}

[tamird]

cc @jakub- because #18538