rustc crashes matching Option<&S> when S is a struct with no fields.

[jakerr]

Version: f0bad90

OSX 10.9.1
rustc 0.10-pre
host: x86_64-apple-darwin

Minimal reproduction:

struct S;

fn main() {
  let s = &S;
  let opt_s: Option<&S> = Some(s);
  match  opt_s {
    Some(&S) => println!("{:?}", S),
    _ => {}
  }
}

causes crash: error: internal compiler error: only scalars and strings supported in compare_values

back trace:

Breakpoint 1, 0x00000001000dcf10 in rust_fail ()
(gdb) bt
#0  0x00000001000dcf10 in rust_fail ()
#1  0x00000001000dceee in rt::unwind::Unwinder::begin_unwind::h5bab6b74dc9914dcZVi::v0.10.pre ()
#2  0x00000001000131a9 in rt::unwind::begin_unwind_inner::h49aeb912c6a4ce4eQ4i::v0.10.pre ()
#3  0x0000000100a42202 in rt::unwind::begin_unwind::h2c64224fbfd78a986q5::v0.10.pre ()
#4  0x0000000100a42be0 in diagnostic::Handler::fatal::h41c181a6acba83c3L2b::v0.10.pre ()
#5  0x0000000100a43158 in diagnostic::Handler::bug::h59bf254d007669aar6b::v0.10.pre ()
#6  0x0000000100ff20f1 in driver::session::Session_::bug::h1251c6a7576ff383qEj::v0.10.pre ()
#7  0x00000001011203df in middle::trans::_match::compile_submatch_continue::hd376baa48abf54ad6Mt::v0.10.pre ()
#8  0x0000000101115e6f in middle::trans::_match::compile_submatch::h9b25cc24b7fe47d0vFt::v0.10.pre ()
#9  0x000000010111c5dc in middle::trans::_match::compile_submatch_continue::hd376baa48abf54ad6Mt::v0.10.pre ()
#10 0x0000000101115e6f in middle::trans::_match::compile_submatch::h9b25cc24b7fe47d0vFt::v0.10.pre ()
#11 0x000000010111ee47 in middle::trans::_match::compile_submatch_continue::hd376baa48abf54ad6Mt::v0.10.pre ()
#12 0x0000000101115e6f in middle::trans::_match::compile_submatch::h9b25cc24b7fe47d0vFt::v0.10.pre ()
#13 0x00000001010a9067 in middle::trans::_match::trans_match::h804a8fd442d5bb1aEcu::v0.10.pre ()
#14 0x000000010109795d in middle::trans::expr::trans_rvalue_dps_unadjusted::hce8904b279cf7d8amuf::v0.10.pre ()
#15 0x000000010101a312 in middle::trans::expr::trans_into::hced97041bceb57efdAe::v0.10.pre ()
#16 0x000000010101b027 in middle::trans::controlflow::trans_block::h830e6540e96f62b384a::v0.10.pre ()
#17 0x00000001010f7f42 in middle::trans::base::trans_closure::h356b84d4c18f206ePep::v0.10.pre ()
#18 0x0000000100ff2a5a in middle::trans::base::trans_fn::he7de539c4580c505Jmp::v0.10.pre ()
#19 0x0000000100fee4c2 in middle::trans::base::trans_item::hc20a2c61f41ea0d4vyp::v0.10.pre ()
#20 0x00000001010feb6f in middle::trans::base::trans_mod::h69d707bdeb3376956Dp::v0.10.pre ()
#21 0x00000001011072ee in middle::trans::base::trans_crate::h12811b8fac70f7c81pr::v0.10.pre ()
#22 0x0000000101613a58 in driver::driver::phase_4_translate_to_llvm::h784570c37ae178b9q6h::v0.10.pre ()
#23 0x0000000101617196 in driver::driver::compile_input::h794f8e6e3126fa9dpli::v0.10.pre ()
#24 0x000000010163ab82 in run_compiler::h5cec0c25fef797c6Rcq::v0.10.pre ()
#25 0x000000010164cbbd in main_args::closure ()
#26 0x000000010164b1f2 in monitor::closure ()
#27 0x000000010164620b in task::TaskBuilder::try::closure ()
#28 0x000000010060e60c in task::bootstrap_green_task::closure ()
#29 0x00000001000d5d78 in rt::task::Task::run::closure ()
#30 0x00000001000dfc2c in rust_try ()
#31 0x000000010060e4c5 in task::bootstrap_green_task::hbb0150eeae2a78081bc::v0.10.pre ()

If a field is added to the struct in the above repro case the crash does not occur.

[eddyb]

This fails:

struct S;
match Some(&S) {
    Some(&S) => {},
    _x => {}
}

This doesn't:

struct S;
match Some(&S) {
    Some(&S) => {},
    None => {}
}

It also doesn't trigger if I replace S with () or &S with _ (or &_).