ICE: misplaced `$crate` in macro

[klutzy]

macro_rules! a { () => ($crate) }
a!();

fn main() {}

error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. 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
thread 'rustc' panicked at 'index out of bounds: the len is 1 but the index is 1', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/lib.rs:1

stack backtrace:
   1:     0x7f8fc2882410 - sys::backtrace::write::hb159f9850e834894l1s
   2:     0x7f8fc28a7150 - failure::on_fail::hd4fb51e7b66e269fxgz
   3:     0x7f8fc280cf20 - rt::unwind::begin_unwind_inner::he95e3015bc1198c6tVy
   4:     0x7f8fc280d8f0 - rt::unwind::begin_unwind_fmt::h300d0aa3e383be9d0Ty
   5:     0x7f8fc28a6fa0 - rust_begin_unwind
   6:     0x7f8fc28eeb10 - panicking::panic_fmt::h6cac417771adde6dn6k
   7:     0x7f8fc28f4920 - panicking::panic_bounds_check::h53e228d6998f5fcao5k
   8:     0x7f8fbd5132c0 - ast::TokenTree::get_tt::h96da5eb3848d084fM9m
   9:     0x7f8fbd5e4f60 - ext::tt::transcribe::tt_next_token::h516df05456a3cb49Ewi
  10:     0x7f8fbd5f16a0 - ext::tt::transcribe::new_tt_reader::h94749376f99cf73fToi
  11:     0x7f8fbd7dc320 - ext::tt::macro_rules::MacroRulesMacroExpander.TTMacroExpander::expand::h4430c94e783ad09bFjj
  12:     0x7f8fbd726a20 - ext::expand::expand_item_mac::hde1d20ded6017125YAe
  13:     0x7f8fbd723970 - ext::expand::expand_item::h73beca611c915148lre
  14:     0x7f8fbd7313a0 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h48955fe1515deaf2cbf
  15:     0x7f8fbd731340 - fold::noop_fold_mod::unboxed_closure.56493
  16:     0x7f8fbd7312d0 - option::Option<T>::map::h10326325581045625383
  17:     0x7f8fbd730d00 - vec::Vec<T>.FromIterator<T>::from_iter::h3348474091482747485
  18:     0x7f8fbd72ee70 - fold::noop_fold_mod::h7835387410379147079
  19:     0x7f8fbd72a270 - ext::expand::expand_item_underscore::h51bed06fced9f01aMye
  20:     0x7f8fbd728b40 - fold::noop_fold_item_simple::h11155469096104082651
  21:     0x7f8fbd728610 - ptr::P<T>::map::h14531937285677412610
  22:     0x7f8fbd723970 - ext::expand::expand_item::h73beca611c915148lre
  23:     0x7f8fbd7313a0 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h48955fe1515deaf2cbf
  24:     0x7f8fbd78edb0 - ext::expand::expand_crate::h22541f1a00aff27ftff
  25:     0x7f8fc2dfe690 - driver::phase_2_configure_and_expand::unboxed_closure.17996
  26:     0x7f8fc2dba950 - driver::phase_2_configure_and_expand::ha7022ac115dbbd06Sja
  27:     0x7f8fc2db0b50 - driver::compile_input::h4f21f66f6761bb22vba
  28:     0x7f8fc2e79640 - thunk::F.Invoke<A, R>::invoke::h1208443586143045988
  29:     0x7f8fc2e783f0 - rt::unwind::try::try_fn::h4735177180287591181
  30:     0x7f8fc290b810 - rust_try_inner
  31:     0x7f8fc290b800 - rust_try
  32:     0x7f8fc2e78740 - thunk::F.Invoke<A, R>::invoke::h6623100047367797814
  33:     0x7f8fc28933d0 - sys::thread::thread_start::h89f54a8cba556c09RSv
  34:     0x7f8fbcda1fe0 - start_thread
  35:     0x7f8fc24bcc99 - __clone
  36:                0x0 - <unknown>

(rustc ea6f65c / 2015-01-06 19:47:08 +0000)

[tamird]

Triage: still ICEs.

[steveklabnik]

This no longer ICEs for me!

error: expected one of `!` or `::`, found `<eof>`
 --> foo.rs:1:25
  |
1 | macro_rules! a { () => ($crate) }
  |