rustc panic on "let a = [];" -- cat_expr Errd then core dump

[andybalaam]

I got a crash with a very small program. When I tried to use RUST_BACKTRACE=1 rustc dumped core, but github will not allow me to upload the core file, even 7zipped.

$ cat tmp.rs
fn main()
{
let a = [];
}

$ rustc tmp.rs
tmp.rs:4:13: 4:15 error: internal compiler error: cat_expr Errd
tmp.rs:4 let a = [];
^~
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
note: run with RUST_BACKTRACE=1 for a backtrace
thread 'rustc' panicked at 'Box', /build/buildd/rust-1.0.0-beta-201504071629b41f2dfvivid/src/libsyntax/diagnostic.rs:131

$ RUST_BACKTRACE=1 rustc tmp.rs
tmp.rs:4:13: 4:15 error: internal compiler error: cat_expr Errd
tmp.rs:4 let a = [];
^~
Illegal instruction (core dumped)

$ gdb /usr/bin/rustc core

Reading symbols from /usr/bin/rustc...(no debugging symbols found)...done.
[New LWP 2214]
[New LWP 2213]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `rustc tmp.rs'.
Program terminated with signal SIGILL, Illegal instruction.
#0 0x00007f65adc50d32 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so

(gdb) where
#0 0x00007f65adc50d32 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#1
#2 0x00007f65a5bea630 in ?? ()
#3 0x00007f65adce0907 in backtrace_pcinfo () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#4 0x00007f65adc3b55c in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#5 0x00007f65a79305b9 in _Unwind_Backtrace () from /lib/x86_64-linux-gnu/libgcc_s.so.1
#6 0x00007f65adc3ae39 in sys::backtrace::write::h3ac5855d9fa0b426kHC () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#7 0x00007f65adc66358 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#8 0x00007f65adb9dea4 in rt::unwind::begin_unwind_inner::h341bf419a797aa0eCzI () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#9 0x00007f65aaf24fae in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libsyntax-4e7c5e5c.so
#10 0x00007f65aaf24f54 in diagnostic::SpanHandler::span_bug::hc13b41cf2fb19457ImB () from /usr/lib/rust/rust-1.0.0-beta/lib/libsyntax-4e7c5e5c.so
#11 0x00007f65ab7de9d4 in session::Session::span_bug::h387971b3ca6d9dafqQq () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc-4e7c5e5c.so
#12 0x00007f65ac89e71e in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#13 0x00007f65ac89f24b in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#14 0x00007f65ac899716 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#15 0x00007f65ac9344a2 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#16 0x00007f65ac92df85 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#17 0x00007f65aca079e7 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#18 0x00007f65aca01f34 in check_crate::h88daf35079354687asC () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_typeck-4e7c5e5c.so
#19 0x00007f65ae2bb1ee in driver::phase_3_run_analysis_passes::hd95dbb6da23a4f8fgGa () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#20 0x00007f65ae29f046 in driver::compile_input::h646544737bce2e91Qba () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#21 0x00007f65ae3565f6 in run_compiler::h372ae4e1f28ce38fS4b () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#22 0x00007f65ae353f0e in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#23 0x00007f65ae35344a in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#24 0x00007f65adce29e9 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#25 0x00007f65adce29d6 in rust_try () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#26 0x00007f65ae35371c in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/librustc_driver-4e7c5e5c.so
#27 0x00007f65adc51342 in ?? () from /usr/lib/rust/rust-1.0.0-beta/lib/libstd-4e7c5e5c.so
#28 0x00007f65a7b3d6aa in start_thread (arg=0x7f65a5bff700) at pthread_create.c:333
#29 0x00007f65ad805eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

$ rustc --version --verbose
rustc 1.0.0-dev (built 2015-04-07)
binary: rustc
commit-hash: unknown
commit-date: unknown
build-date: 2015-04-07
host: x86_64-unknown-linux-gnu
release: 1.0.0-dev

[pnkfelix]

what the heck, a core dump after a cat_expr Errd ???

[huonw]

NB. Your rustc seems to be a month old now, it may be already fixed in the 1.0.0 stable compiler or maybe in the nightlies.

[andybalaam]

Apologies, with recent rust this seems to work fine. I'll try this again on the same machine before I close the issue, but on this (different) machine, with recent rust, I get:

$ rustc tmp.rs
tmp.rs:3:9: 3:15 error: cannot determine a type for this local variable: unconstrained type [E0102]
tmp.rs:3 let a = [];
^~~~~~
error: aborting due to previous error

$ rustc --version --verbose
rustc 1.2.0-dev (2dd5ad0 2015-05-18) (built 2015-05-18)
binary: rustc
commit-hash: 2dd5ad0
commit-date: 2015-05-18
build-date: 2015-05-18
host: x86_64-unknown-linux-gnu
release: 1.2.0-dev

[andybalaam]

Yes, works in rust built from latest git. Apologies for the noise.