ICE when compiling an FFI binding with a certain type

[Blei]

The following small binding produces an ICE:

use libc::*;

pub struct KEYGEN {
    hash_algorithm: [c_uint]/2,
    count: uint32_t,
    salt: *c_void,
    salt_size: uint32_t,
}

extern {
    pub fn mhash_keygen_ext(++data: KEYGEN);
}

According to some comments in the IRC channel, the ++ mode is necessary to comply to the C ABI.

Trace:

% RUST_LOG=rustc=0,::rt::backtrace rustc --lib fail.rs 
warning: missing crate link meta `name`, using `fail` as default
warning: missing crate link meta `vers`, using `0.0` as default
rust: task failed at 'index out of bounds: the len is 3 but the index is 3', /home/philipp/programming/rust-git/src/rustc/middle/trans/foreign.rs:138
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x5d)[0x7f96e557670d]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(+0x31fed)[0x7f96e558dfed]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(upcall_fail+0x1a8)[0x7f96e5579008]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(_ZN2rt20rt_fail_bounds_check17_e739cc78d15657703_04E+0x1a0)[0x7f96e6b9c360]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24c007)[0x7f96e5a0a007]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24c17a)[0x7f96e5a0a17a]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24c2e8)[0x7f96e5a0a2e8]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24c2e8)[0x7f96e5a0a2e8]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24d4b4)[0x7f96e5a0b4b4]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24f060)[0x7f96e5a0d060]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24cdae)[0x7f96e5a0adae]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x24fff4)[0x7f96e5a0dff4]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x252d50)[0x7f96e5a10d50]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6middle5trans7foreign17trans_foreign_mod17_3368894e4dbb26b13_04E+0xce)[0x7f96e59bd0ae]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6middle5trans4base10trans_item16_de1f8cec64c49493_04E+0x19f)[0x7f96e58ae18f]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6middle5trans4base9trans_mod16_583ddc9f4c3703c3_04E+0x8f)[0x7f96e59bcf5f]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6middle5trans4base11trans_crate17_fd92dc19557ff9d53_04E+0x149a)[0x7f96e59d69ca]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6driver6driver12compile_upto15_aa75a51be7967c3_04E+0x2560)[0x7f96e5e213b0]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(+0x68d2a0)[0x7f96e5e4b2a0]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustc-c84825241471686d-0.4.so(_ZN6driver6driver13compile_input17_a1da55cea41e7ba53_04E+0xbd)[0x7f96e5e2379d]
rustc[0x408d68]
rustc[0x4120c4]
rustc[0x40e543]
rustc[0x40d1fc]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x75ef4)[0x7f96e6bd0ef4]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0xb7150)[0x7f96e6c12150]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f96e5576eb4]
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=0,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /home/philipp/programming/rust-git/src/rustc/driver/rustc.rs:275
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x5d)[0x7f96e557670d]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(+0x31fed)[0x7f96e558dfed]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(upcall_fail+0x1a8)[0x7f96e5579008]
rustc(_rust_main+0xbf4)[0x411c94]
rustc[0x4120c4]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f96e5576eb4]
rust: domain main @0x1d99240 root task failed
rust: task failed at 'killed', /home/philipp/programming/rust-git/src/libcore/task.rs:662
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x5d)[0x7f96e557670d]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(+0x31fed)[0x7f96e558dfed]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(upcall_fail+0x1a8)[0x7f96e5579008]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(_ZN4task5yield16_9531951b4f79f8b3_04E+0xbd)[0x7f96e6bba4ad]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x90d76)[0x7f96e6bebd76]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(_ZN7private11weaken_task16_1454432f47864e73_04E+0xd2)[0x7f96e6bebbb2]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x90aab)[0x7f96e6bebaab]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0xb7150)[0x7f96e6c12150]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x8fe00)[0x7f96e6beae00]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x8f79e)[0x7f96e6bea79e]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x8ee06)[0x7f96e6be9e06]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x75ef4)[0x7f96e6bd0ef4]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/libcore-c3ca5d77d81b46c1-0.4.so(+0xb7150)[0x7f96e6c12150]
/home/philipp/programming/rust-git/x86_64-unknown-linux-gnu/stage2/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f96e5576eb4]