ICE with unboxed closures

[netvl]

This very simple program:

#![feature(unboxed_closures)]

fn make_closure() {
    let mut acc = 0.0;
    box move |&mut: i: f64| {
        acc += i; 
        acc
    };
}

fn main() {}

crashes the compiler with the following error:

error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'assertion failed: `(left == right) && (right == left)` (left: `McInherited`, right: `McDeclared`)', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/librustc/middle/borrowck/check_loans.rs:830

stack backtrace:
   1:     0x7fa57c579860 - rt::backtrace::imp::write::he1d07ecb5c09ef73Ocq
   2:     0x7fa57c57c990 - failure::on_fail::h76802abdf02d9229byq
   3:     0x7fa580ad6ac0 - unwind::begin_unwind_inner::hb92ca1198fd23157Yxd
   4:     0x7fa580ad6600 - unwind::begin_unwind_fmt::h5e0607d8f87b6529qvd
   5:     0x7fa58130f300 - middle::borrowck::check_loans::CheckLoanCtxt<'a, 'tcx>.euv..Delegate::mutate::h8f1bc217b6ff75a2g5f
   6:     0x7fa58131e410 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::mutate_expr::h3610340025408968702
   7:     0x7fa581317810 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::walk_expr::h7878549864954814134
   8:     0x7fa58131d550 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::consume_expr::h1441929135172233355
   9:     0x7fa581317410 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::walk_block::h1855207539966477442
  10:     0x7fa581317810 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::walk_expr::h7878549864954814134
  11:     0x7fa58131d550 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::consume_expr::h1441929135172233355
  12:     0x7fa581317410 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, TYPER>::walk_block::h1855207539966477442
  13:     0x7fa581310be0 - middle::borrowck::check_loans::check_loans::h79a9c285140c1595y8f
  14:     0x7fa581348ca0 - middle::borrowck::borrowck_fn::h0540d52a3b7fb27b1Tj
  15:     0x7fa58134a260 - visit::walk_expr::h4135272309649785660
  16:     0x7fa58134a780 - visit::walk_block::h14476049905583047865
  17:     0x7fa581348ca0 - middle::borrowck::borrowck_fn::h0540d52a3b7fb27b1Tj
  18:     0x7fa58134abe0 - visit::walk_item::h8478938835045244904
  19:     0x7fa581349580 - middle::borrowck::check_crate::h86fc9e47401bae40MMj
  20:     0x7fa581139c90 - util::common::time::h13858161161014839769
  21:     0x7fa5819ea1b0 - driver::driver::phase_3_run_analysis_passes::h04ee49849c18416b69z
  22:     0x7fa5819e5630 - driver::driver::compile_input::hd4ba06b74713782dRQz
  23:     0x7fa581a70350 - driver::run_compiler::h014078c5025dc703vDD
  24:     0x7fa581a70200 - driver::run::closure.145641
  25:     0x7fa581153b20 - task::TaskBuilder<S>::try_future::closure.103153
  26:     0x7fa581153900 - task::TaskBuilder<S>::spawn_internal::closure.103124
  27:     0x7fa580e20740 - task::NativeSpawner.Spawner::spawn::closure.8435
  28:     0x7fa580b2fd10 - rust_try_inner
  29:     0x7fa580b2fd00 - rust_try
  30:     0x7fa580ad4380 - unwind::try::hdee5a3b0466d278eGmd
  31:     0x7fa580ad4200 - task::Task::run::h27d9c4b6d2601e28kCc
  32:     0x7fa580e20480 - task::NativeSpawner.Spawner::spawn::closure.8375
  33:     0x7fa580ad5ad0 - thread::thread_start::h5e6e53ee3afb8775vWc
  34:     0x7fa57b924060 - start_thread
  35:     0x7fa5807a5489 - __clone
  36:                0x0 - <unknown>

Without move it works.

This seems to be a regression, as this program does work with Rust nightly released at 2014-10-14.

[bkoropoff]

This is probably my fault, taking a look