rustc --ls segfaults on invalid files

[ghost]

$ echo > foo
$ rustc --ls foo
Segmentation fault (core dumped)
$ gdb -q --args rustc --ls foo
Reading symbols from /home/jurily/sys/bin/rustc...(no debugging symbols found)...done.
(gdb) run
Starting program: /home/jurily/sys/bin/rustc --ls foo
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0x7ffff7f5a700 (LWP 1017)]
[New Thread 0x7ffff2c59700 (LWP 1018)]
[New Thread 0x7ffff239e700 (LWP 1019)]
[New Thread 0x7ffff1b9d700 (LWP 1020)]
[New Thread 0x7ffff139c700 (LWP 1021)]
[New Thread 0x7ffff0b9b700 (LWP 1022)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff7f5a700 (LWP 1017)]
0x00007ffff5377fad in LLVMDisposeMemoryBuffer () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
(gdb) bt
#0  0x00007ffff5377fad in LLVMDisposeMemoryBuffer () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#1  0x00007ffff4830cf1 in metadata::loader::get_metadata_section::h3330abedea556404aF::v0.9.pre () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#2  0x00007ffff4831714 in metadata::loader::list_file_metadata::hc98d9a2045147b9caN::v0.9.pre () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#3  0x00007ffff484f40e in driver::driver::list_metadata::h8d94c62f4b32e7f4av::v0.9.pre () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#4  0x00007ffff48627aa in run_compiler::h737284f8d64daad7aC::v0.9.pre () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#5  0x00007ffff4870f9d in main_args::anon::expr_fn::at () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#6  0x00007ffff486eff4 in monitor::anon::expr_fn::aO () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#7  0x00007ffff486809e in task::TaskBuilder::try::anon::expr_fn::sEaCag () from /home/jurily/sys/bin/../lib/librustc-5b94a16f-0.9-pre.so
#8  0x00007ffff7422638 in task::__extensions__::build_start_wrapper::anon::anon::expr_fn::ab () from /home/jurily/sys/bin/../lib/libgreen-3b3a1962-0.9-pre.so
#9  0x00007ffff7767d08 in rt::task::__extensions__::run::anon::expr_fn::aW () from /home/jurily/sys/bin/../lib/libstd-04ff901e-0.9-pre.so
#10 0x00007ffff776f1dc in rust_try () from /home/jurily/sys/bin/../lib/libstd-04ff901e-0.9-pre.so
#11 0x00007ffff7767a75 in rt::task::Task::run::he7be25f7e8ea1d74YJaS::v0.9.pre () from /home/jurily/sys/bin/../lib/libstd-04ff901e-0.9-pre.so
#12 0x00007ffff74220fb in task::__extensions__::build_start_wrapper::anon::expr_fn::aV () from /home/jurily/sys/bin/../lib/libgreen-3b3a1962-0.9-pre.so
#13 0x0000000000000000 in ?? ()

[alexcrichton]

Thanks for the backtrace! Looks like this is a bug in our usage of LLVM's archive bindings.