ICE with unicode identifiers

[huonw]

fn main() {
    enum Sets { ℕ, ℝ, ℤ };
    println(fmt!("%?", (ℕ, ℝ, ℤ)))
}

These are in the XID_Start unicode category according to this.

rust: task failed at 'assertion failed: is_char_boundary(s, end)', /home/huon/rust/src/libcore/str.rs:469
/usr/local/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7fcf9619ebab]
/usr/local/bin/../lib/librustrt.so(+0x2cb49)[0x7fcf961afb49]
/usr/local/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7fcf961a0b50]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x11835b)[0x7fcf99aab35b]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x118302)[0x7fcf99aab302]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys14__extensions__9meth_69349fail_with17_ac9eb45dc42bd6906_07preE+0x6b)[0x7fcf999f7ddb]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3str5slice16_885ba6d6c535c966_07preE+0x2f6)[0x7fcf99a45216]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x734f10)[0x7fcf98452f10]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x72e68a)[0x7fcf9844c68a]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x737670)[0x7fcf98455670]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xf71a7)[0x7fcf98ce81a7]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xfa929)[0x7fcf98ceb929]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xf9077)[0x7fcf98cea077]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xef8a8)[0x7fcf98ce08a8]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0x679d9)[0x7fcf98c589d9]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xf8c41)[0x7fcf98ce9c41]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xfb932)[0x7fcf98cec932]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xf7760)[0x7fcf98ce8760]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xeee62)[0x7fcf98cdfe62]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0x679d9)[0x7fcf98c589d9]
/usr/local/bin/../lib/libsyntax-84efebcb12c867a2-0.7-pre.so(+0xf679c)[0x7fcf98ce779c]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x2cc071)[0x7fcf97fea071]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle4lint11check_crate17_402986ad7fcf72da6_07preE+0x44d)[0x7fcf984553bd]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9c6d12)[0x7fcf986e4d12]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x6c4b35)[0x7fcf983e2b35]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_rest15_145f45ce42f9c06_07preE+0x24d8)[0x7fcf986dfe78]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_upto16_2fb35e5cb55ee9d6_07preE+0x192)[0x7fcf986e5092]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver13compile_input17_b22f68de44847bf06_07preE+0x107)[0x7fcf986e5517]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN12run_compiler17_faf6647f92eef22b6_07preE+0x2bf4)[0x7fcf98711314]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa051de)[0x7fcf987231de]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa02cec)[0x7fcf98720cec]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa00e7c)[0x7fcf9871ee7c]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa054b0)[0x7fcf987234b0]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xe36e3)[0x7fcf99a766e3]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x15bbc8)[0x7fcf99aeebc8]
/usr/local/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7fcf9619f554]
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /home/huon/rust/src/librustc/rustc.rc:349
/usr/local/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7fcf9619ebab]
/usr/local/bin/../lib/librustrt.so(+0x2cb49)[0x7fcf961afb49]
/usr/local/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7fcf961a0b50]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x11835b)[0x7fcf99aab35b]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x1183a2)[0x7fcf99aab3a2]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xc3cc4)[0x7fcf99a56cc4]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN7monitor17_9fc4cea5345c48116_07preE+0x6bc5)[0x7fcf987190d5]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa054b0)[0x7fcf987234b0]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN4main15_c4de63b748e03d6_07preE+0x69)[0x7fcf98723119]
rustc(_rust_main+0x2e)[0x400c7e]
/usr/local/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7fcf9619f554]
rust: domain main @0x919410 root task failed

[pnkfelix]

nominating for maturity milestone 2: "backwards compatible."

[emberian]

Can not reproduce on 0bd67f6, closing.