Syntax extension example in book fails to compile

[russellmcc]

I was trying to get started with compiler plug-ins, so I tried to compile the roman numeral syntax extension example. The plug-in itself compiled properly but using it lead to a panic:

rustc --version
rustc 1.2.0-nightly (9ad0063a1 2015-06-20)

   Compiling rn_test v0.1.0 (file:///Users/russruss/proj/learnprog/rust/rn_use_test)
     Running `rustc /Users/russruss/proj/learnprog/rust/rn_test/src/lib.rs --crate-name rn_test --crate-type dylib -C prefer-dynamic -g -C metadata=54f89a58f992a7a5 -C extra-filename=-54f89a58f992a7a5 --out-dir /Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps --emit=dep-info,link -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps`
   Compiling rn_use_test v0.1.0 (file:///Users/russruss/proj/learnprog/rust/rn_use_test)
     Running `rustc src/main.rs --crate-name rn_use_test --crate-type bin -g --out-dir /Users/russruss/proj/learnprog/rust/rn_use_test/target/debug --emit=dep-info,link -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps --extern rn_test=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps/librn_test-54f89a58f992a7a5.dylib`
error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
thread 'rustc' panicked at 'index out of bounds: the len is 60 but the index is 66', ../src/libcollections/vec.rs:1362

stack backtrace:
   1:        0x10763bd35 - sys::backtrace::write::hedd23d39cd9e7a9azns
   2:        0x107644562 - panicking::on_panic::haefb92227f11fe31HHw
   3:        0x107600542 - rt::unwind::begin_unwind_inner::hbd25dce0c263cfbdTpw
   4:        0x107601299 - rt::unwind::begin_unwind_fmt::h4e41fe74d3e63554Zow
   5:        0x10764411c - rust_begin_unwind
   6:        0x107698045 - panicking::panic_fmt::h03749e86046e7c85E8B
   7:        0x1076927c5 - panicking::panic_bounds_check::hed26c3125161d258K7B
   8:        0x10c7ebca7 - util::interner::StrInterner::get::h619fad0592b15e68Fpa
   9:        0x107b7b404 - parse::token::get_name::hd0ab16ef5f33cd25BaT
  10:        0x107b7b338 - parse::token::get_ident::h3505388221878bd1SaT
  11:        0x107b779dd - expand_rn::h65ba18f76bf4dba9saa
  12:        0x10c268a9e - ext::base::F.TTMacroExpander::expand::h3915518365159958189
  13:        0x1050cdc2b - ext::expand::expand_expr::closure.64694
  14:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  15:        0x1050d13c6 - fold::noop_fold_expr::h7579904053176116772
  16:        0x1050c94b2 - ext::expand::expand_expr::closure.64694
  17:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  18:        0x1050d2dd5 - fold::noop_fold_expr::h7579904053176116772
  19:        0x1050c94b2 - ext::expand::expand_expr::closure.64694
  20:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  21:        0x1050d1a9d - fold::noop_fold_expr::h7579904053176116772
  22:        0x1050c94b2 - ext::expand::expand_expr::closure.64694
  23:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  24:        0x1050d222c - fold::noop_fold_expr::h7579904053176116772
  25:        0x1050c94b2 - ext::expand::expand_expr::closure.64694
  26:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  27:        0x10512257e - ext::expand::expand_block_elts::closure.65414
  28:        0x1051208de - ext::expand::expand_block_elts::closure.65395
  29:        0x1050dc92a - ext::expand::expand_block_elts::hdf84aa5274590198wPb
  30:        0x1051202f2 - ext::expand::expand_block::h24d11839a7d766c2ROb
  31:        0x1050d2933 - fold::noop_fold_expr::h7579904053176116772
  32:        0x1050c94b2 - ext::expand::expand_expr::closure.64694
  33:        0x1050c92b0 - ext::expand::expand_expr::h3bd09218499b8fc1T3a
  34:        0x105119b70 - fold::noop_fold_stmt::h7591722087387603310
  35:        0x1050f586e - ext::expand::expand_stmt::h7376ca7d2a57107eAEb
  36:        0x1050f884c - iter::FlatMap<I, U, F>.Iterator::next::h9212628285290734802
  37:        0x1050f7987 - util::small_vector::SmallVector<T>.FromIterator<T>::from_iter::h6873315887265380074
  38:        0x1050f6891 - ext::expand::expand_stmt::h7376ca7d2a57107eAEb
  39:        0x105122473 - ext::expand::expand_block_elts::closure.65401
  40:        0x105122126 - iter::FlatMap<I, U, F>.Iterator::next::h5647249170750674838
  41:        0x105120d75 - vec::Vec<T>.FromIterator<T>::from_iter::h3784764330073977859
  42:        0x10512063d - ext::expand::expand_block_elts::closure.65395
  43:        0x1050dc92a - ext::expand::expand_block_elts::hdf84aa5274590198wPb
  44:        0x1051202f2 - ext::expand::expand_block::h24d11839a7d766c2ROb
  45:        0x1050dc2fc - ext::expand::expand_and_rename_fn_decl_and_block::he9fd348cb5bd2755Vic
  46:        0x1050e389d - ext::expand::expand_item_underscore::hd72d084e46a32acb0sb
  47:        0x1051474e4 - fold::Folder::fold_item_simple::h2914524661209321778
  48:        0x1051470b3 - ptr::P<T>::map::h12098919794669766025
  49:        0x1050e0d6d - ext::expand::expand_annotatable::h18105362623436c9SZb
  50:        0x1050dcab1 - ext::expand::expand_item::h6e40b5a3505338c6psb
  51:        0x1050e99aa - iter::FlatMap<I, U, F>.Iterator::next::h6906720827660212339
  52:        0x1050e88b7 - vec::Vec<T>.FromIterator<T>::from_iter::h14651162845813094091
  53:        0x1050e807f - fold::noop_fold_mod::h622930514852582360
  54:        0x1050e402e - ext::expand::expand_item_underscore::hd72d084e46a32acb0sb
  55:        0x1051474e4 - fold::Folder::fold_item_simple::h2914524661209321778
  56:        0x1051470b3 - ptr::P<T>::map::h12098919794669766025
  57:        0x1050e17ed - ext::expand::expand_annotatable::h18105362623436c9SZb
  58:        0x1050dcab1 - ext::expand::expand_item::h6e40b5a3505338c6psb
  59:        0x10515078f - ext::expand::expand_crate::hbe292a2cc58dc8c6qrc
  60:        0x103b22b92 - driver::phase_2_configure_and_expand::closure.21464
  61:        0x103ad6f42 - driver::phase_2_configure_and_expand::hbecc670a8758f096ita
  62:        0x103ac67cd - driver::compile_input::h28deac6d4a93d734Tba
  63:        0x103ba37af - run_compiler::h64b107044b742926x7b
  64:        0x103ba1063 - boxed::F.FnBox<A>::call_box::h14920861784355226004
  65:        0x103ba0827 - rt::unwind::try::try_fn::h13446674677803050384
  66:        0x1076ceea8 - rust_try_inner
  67:        0x1076cee95 - rust_try
  68:        0x10762e275 - rt::unwind::try::inner_try::he9303ddbfc52c927Mlw
  69:        0x103ba0a58 - boxed::F.FnBox<A>::call_box::h8722405328789365899
  70:        0x10764301d - sys::thread::Thread::new::thread_start::h20bd66ec5dc1b5ec6Jv
  71:     0x7fff9844e267 - _pthread_body
  72:     0x7fff9844e1e4 - _pthread_start

Could not compile `rn_use_test`.

Caused by:
  Process didn't exit successfully: `rustc src/main.rs --crate-name rn_use_test --crate-type bin -g --out-dir /Users/russruss/proj/learnprog/rust/rn_use_test/target/debug --emit=dep-info,link -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug -L dependency=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps --extern rn_test=/Users/russruss/proj/learnprog/rust/rn_use_test/target/debug/deps/librn_test-54f89a58f992a7a5.dylib` (exit code: 101)

[russellmcc]

I can't reproduce this on 320bd6f, so I guess it's probably fixed