Compiler crash with unnamed parameter.

[compmstr]

If you have a default implementation for a trait method, and don't provide a name for the parameter, the compiler will crash instead of showing a syntax error.

ex:

trait Drawable{
fn draw(&mut self, f32){} // This will crash the compiler
}

trait Drawable{
fn draw(&mut self, d_time: f32){} // This will compile and work as intended
}

The backtrace when the compiler crashes is as follows:
task 'rustc' failed at 'index out of bounds: the len is 0 but the index is 0', /home/corey/programming/rust/versions/rust/src/librustc/lib.rs:1
stack backtrace:
1: 0x7ffe9dd3a600 - rt::backtrace::imp::write::h43ed367ff6ec8062mHb::v0.10.pre
2: 0x7ffe9dc9fe10 - rt::unwind::begin_unwind_inner::h429b9db6779a12dcQhb::v0.10.pre
3: 0x7ffe9dc9fd80 - rt::unwind::begin_unwind::h79798f4b44fbb17bqhb::v0.10.pre
4: 0x7ffe9dd3a210 - rt::unwind::begin_unwind_raw::h0b348fcefe22c823Zeb::v0.10.pre
5: 0x7ffe9dc9f0b0 - rt::unwind::fail_::h8824f9d64c0ec9d7Dcb::v0.10.pre
6: 0x7ffe9dd3a280 - rt::unwind::fail_bounds_check::closure.40769
7: 0x7ffe9dca1010 - rt::unwind::fail_bounds_check::hc2d5b6f9b5fc56a20cb::v0.10.pre
8: 0x7ffe9eaf7f20 - middle::lint::Context$LT$$x27a$GT$.Visitor$LT$$LP$$RP$$GT$::visit_pat::h7a9472f62848a24fC9B::v0.10.pre
9: 0x7ffe9eafa960 - visit::walk_fn::he10b1e679cee0eefj6u::v0.10.pre
10: 0x7ffe9eafa8e0 - middle::lint::Context$LT$$x27a$GT$.Visitor$LT$$LP$$RP$$GT$::visit_fn::closure.71452
11: 0x7ffe9eafaa90 - middle::lint::Context$LT$$x27a$GT$.Visitor$LT$$LP$$RP$$GT$::visit_fn::closure.71454
12: 0x7ffe9eae0410 - middle::lint::Context$LT$$x27a$GT$::with_lint_attrs::ha94646037287dd66ZTA::v0.10.pre
13: 0x7ffe9eaf73b0 - middle::lint::Context$LT$$x27a$GT$.Visitor$LT$$LP$$RP$$GT$::visit_fn::h45b6e9195921b2a4ucC::v0.10.pre
14: 0x7ffe9eaef7e0 - middle::lint::Context$LT$$x27a$GT$.Visitor$LT$$LP$$RP$$GT$::visit_item::closure.71442
15: 0x7ffe9eae0410 - middle::lint::Context$LT$$x27a$GT$::with_lint_attrs::ha94646037287dd66ZTA::v0.10.pre
16: 0x7ffe9eaf7550 - visit::Visitor::visit_mod::h2cefa0a457a05cdagZw::v0.10.pre
17: 0x7ffe9eb01040 - middle::lint::check_crate::closure.71512
18: 0x7ffe9eae0410 - middle::lint::Context$LT$$x27a$GT$::with_lint_attrs::ha94646037287dd66ZTA::v0.10.pre
19: 0x7ffe9eb007d0 - middle::lint::check_crate::h720ceda6a3842effSiC::v0.10.pre
20: 0x7ffe9eab2910 - util::common::time::h29acbd1a7bd8e027Zch::v0.10.pre
21: 0x7ffe9ee17950 - driver::driver::phase_3_run_analysis_passes::h2519405deb9df491g1e::v0.10.pre
22: 0x7ffe9ee1e4d0 - driver::driver::compile_input::he6ac8834e12409f2tqf::v0.10.pre
23: 0x7ffe9ee42000 - run_compiler::h73da9b5de1b64391p4m::v0.10.pre
24: 0x7ffe9ee55330 - main_args::closure.91104
25: 0x7ffe9ee53c60 - monitor::closure.90989
26: 0x7ffe9ee4f630 - task::TaskBuilder::try::closure.90800
27: 0x7ffea0bb7300 - task::spawn_opts::closure.7479
28: 0x7ffe9dd35d20 - rt::task::Task::run::closure.40674
29: 0x7ffe9dd41110 - rust_try
30: 0x7ffe9dd35b60 - rt::task::Task::run::hca9f4f2190d84d1fV68::v0.10.pre
31: 0x7ffea0bb70a0 - task::spawn_opts::closure.7452
32: 0x7ffe9dd390c0 - rt::thread::thread_start::h3d1b32419b999440nN9::v0.10.pre
33: 0x7ffe9b0aeea0 - start_thread
34: 0x7ffe9d95f999 - __clone
35: 0x0 -

I am running on Lubuntu x86_64.

Thanks for all the great work

[edwardw]

Dupe of #13105?

[compmstr]

Yep, sorry, didn't find that one in the search. Should I close this?

[alexcrichton]

Closing as a dupe of #13105