rustc crashes when called without arguments

[dotdash]

bs@bs:rust (incoming) $ RUST_LOG=rustc=1,::rt::backtrace rustc
rust: task failed at 'word longer than limit!', /home/bs/src/rust/src/libcore/str.rs:729
/home/bs/rust/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f2cffdebc2b]
/home/bs/rust/bin/../lib/librustrt.so(+0x308a9)[0x7f2cffdfc8a9]
/home/bs/rust/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7f2cffdeda60]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x10a23b)[0x7f2cffa0a23b]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x10a1e2)[0x7f2cffa0a1e2]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(_ZN3sys12begin_unwind16_701b8ec61f97ead3_06E+0x71)[0x7f2cff9529c1]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0xab905)[0x7f2cff9ab905]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(_ZN3str17each_split_within16_9397a03c2e16f823_06E+0x167)[0x7f2cff9ab617]
/home/bs/rust/bin/../lib/libstd-4782a756585a81-0.6.so(_ZN7getopts6groups5usage17_8054bef278ffe5323_06E+0x13bb)[0x7f2cff76e36b]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(_ZN5usage17_cabc1a5eac86665f3_06E+0x1f7)[0x7f2cfefa2967]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(+0x8ca514)[0x7f2cfefb5514]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(_ZN12run_compiler17_ed2ef74811c465933_06E+0x65d)[0x7f2cfefa4f6d]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(+0x8c7fe1)[0x7f2cfefb2fe1]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(+0x8c480c)[0x7f2cfefaf80c]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(+0x8ca514)[0x7f2cfefb5514]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0xd2d6e)[0x7f2cff9d2d6e]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x1527c4)[0x7f2cffa527c4]
/home/bs/rust/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f2cffdec474]
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/bs/src/rust/src/librustc/rustc.rc:356
/home/bs/rust/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f2cffdebc2b]
/home/bs/rust/bin/../lib/librustrt.so(+0x308a9)[0x7f2cffdfc8a9]
/home/bs/rust/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7f2cffdeda60]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x10a23b)[0x7f2cffa0a23b]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x10a1e2)[0x7f2cffa0a1e2]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(_ZN3sys12begin_unwind16_701b8ec61f97ead3_06E+0x71)[0x7f2cff9529c1]
/home/bs/rust/bin/../lib/libcore-c3ca5d77d81b46c1-0.6.so(+0x1527c4)[0x7f2cffa527c4]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(_ZN7monitor16_5be8265772b87d83_06E+0x1577)[0x7f2cfefa8fd7]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(+0x8ca514)[0x7f2cfefb5514]
/home/bs/rust/bin/../lib/librustc-c84825241471686d-0.6.so(_ZN4main16_706f4ee7413ae583_06E+0x7e)[0x7f2cfefb512e]
/home/bs/rust/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f2cffdec474]
rust: domain main @0x5bf3c0 root task failed

[jbclements]

This looks to me like a uint issue on line 729 of str.rs, where i - last_start +1 is "smaller than zero", a.k.a. very big. There are probably other bugs involved, too...

[dotdash]

It was actually just a url in the help that was indeed too long, already fixed by #5609