Assignment operator for BigInt causes ICE

[gifnksm]

The following core causes ICE.

extern mod std;

use core::num::{IntConvertible};
use std::bigint::{BigInt};

fn main() {
  let mut n = IntConvertible::from_int::<BigInt>(1);
  n += IntConvertible::from_int::<BigInt>(2);
  println(fmt!("%s", n.to_str()));
}

$ RUST_LOG=rustc=1,::rt::backtrace rustc ng.rs
rust: task failed at 'assertion failed: !bcx.ccx().maps.moves_map.contains(&arg_expr.id)', /home/nksm/pkg/rust-incoming/src/rust/src/librustc/middle/trans/callee.rs:733
/usr/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f345469a5db]
/usr/bin/../lib/librustrt.so(+0x2a619)[0x7f34546ab619]
/usr/bin/../lib/librustrt.so(upcall_fail+0x198)[0x7f345469c518]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x112f6b)[0x7f3456659f6b]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x112f12)[0x7f3456659f12]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys14__extensions__9meth_68459fail_with16_12542417c6a0d836_07preE+0x6b)[0x7f34565a6a7b]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee14trans_arg_expr16_11e9c138e58ce866_07preE+0x1e4c)[0x7f3454b0a3ec]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x22c4c9)[0x7f3454b084c9]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x22c32d)[0x7f3454b0832d]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee10trans_args17_76939082bfb0b4786_07preE+0x1be)[0x7f3454b06cde]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x229e06)[0x7f3454b05e06]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10with_scope15_6b601fbe3c1f9c6_07preE+0x5fc)[0x7f3454ab4eac]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans6callee16trans_call_inner15_adb7958e8922786_07preE+0x126)[0x7f3454aeb926]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x24a183)[0x7f3454b26183]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x243a33)[0x7f3454b1fa33]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x23f2d2)[0x7f3454b1b2d2]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4expr10trans_into16_85d0f7ed7c34fb66_07preE+0xb71)[0x7f3454a66d41]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10trans_stmt16_5122cda3b3b762b6_07preE+0x63d)[0x7f3454a65bad]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x188eda)[0x7f3454a64eda]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x188dfa)[0x7f3454a64dfa]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans11controlflow11trans_block16_808c4aa24555fcf6_07preE+0x1ae)[0x7f3454a6346e]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base13trans_closure17_c01bc4ba445c3ca16_07preE+0xa61)[0x7f3454b8e571]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base8trans_fn17_c54d4263d716d9c36_07preE+0x685)[0x7f3454a18865]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base10trans_item16_2142679ed2f4f8c6_07preE+0x11c9)[0x7f3454a0eef9]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x2b9a28)[0x7f3454b95a28]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x21516a)[0x7f3454af116a]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base9trans_mod16_8f74aeac2aa378f6_07preE+0xa2)[0x7f3454b95532]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle5trans4base11trans_crate17_2ba8db2a9d3fad206_07preE+0x1511)[0x7f3454bb2ad1]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_rest17_3484a7eeb05af7ff6_07preE+0x3e1c)[0x7f345528ea2c]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_upto17_7159fcbbfa2a70e46_07preE+0x192)[0x7f3455292302]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver13compile_input17_5d2d955f23bac1556_07preE+0x107)[0x7f3455292787]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN12run_compiler17_cb41e7e533dbc8f66_07preE+0x2bf4)[0x7f34552be414]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9f43ce)[0x7f34552d03ce]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9f1edc)[0x7f34552cdedc]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9f005c)[0x7f34552cc05c]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9f46a0)[0x7f34552d06a0]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xdf187)[0x7f3456626187]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x1568c8)[0x7f345669d8c8]
/usr/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f345469af54]
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/nksm/pkg/rust-incoming/src/rust/src/librustc/rustc.rc:349
/usr/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f345469a5db]
/usr/bin/../lib/librustrt.so(+0x2a619)[0x7f34546ab619]
/usr/bin/../lib/librustrt.so(upcall_fail+0x198)[0x7f345469c518]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x112f6b)[0x7f3456659f6b]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x112fb2)[0x7f3456659fb2]
/usr/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xbf764)[0x7f3456606764]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN7monitor17_393ba1ffd0fee79d6_07preE+0x6bc5)[0x7f34552c61d5]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x9f46a0)[0x7f34552d06a0]
/usr/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN4main15_c4de63b748e03d6_07preE+0x69)[0x7f34552d0309]
rustc(_rust_main+0x2e)[0x400bfe]
/usr/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f345469af54]
rust: domain main @0x689410 root task failed

The following doesn't cause ICE.

extern mod std;

use core::num::{IntConvertible};
use std::bigint::{BigInt};

fn main() {
  let mut n = IntConvertible::from_int::<BigInt>(1);
  n = n + IntConvertible::from_int::<BigInt>(2);
  println(fmt!("%s", n.to_str()));
}

This may be related to #2528.

[Aatch]

Dupe of #6609