ICE: unexpected panic in InferCtxt

[khernyo]

Compiling the following code causes a panic:

use std::result::Result;
use std::thread;

struct A<H: B> {
    t: H::Timeout,
}

trait B {
    type Timeout;
}

struct C<F> where F: Factory {
    f: F,
}

impl<F> B for C <F> where F: Factory {
    type Timeout = ();
}

struct D<F> where F: Factory {
    a: A<C<F>>,
}

impl<F> D<F> where F: Factory {
    fn new(f: F) -> Result<D<F>, ()> {
        panic!();
    }
}

trait Factory {
}

impl<F, H> Factory for F where H: Handler, F: FnMut(i32) -> H {
}

trait Handler {
}

impl<F> Handler for F where F: Fn(i32) -> () {
}

fn main() {
    thread::spawn(move || {
        D::new(|_| { move |_| { () } });
    });
}

Compiler output:

error: internal compiler error: unexpected panic
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
thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:365

stack backtrace:
   1:     0x7fdef400af19 - sys::backtrace::tracing::imp::write::hd3f07380f094c3d8Pnt
   2:     0x7fdef4008736 - panicking::on_panic::hbcd77a06a59b411aenx
   3:     0x7fdef3fd503e - sys_common::unwind::begin_unwind_inner::h57bfaf3a147bd49affs
   4:     0x7fdef3fd5a78 - sys_common::unwind::begin_unwind_fmt::h86f74adb98a0354bles
   5:     0x7fdef40081d1 - rust_begin_unwind
   6:     0x7fdef4054acf - panicking::panic_fmt::hb3d424cb509d7c29TaG
   7:     0x7fdef404e0e8 - panicking::panic::hea7947f7c1336ee9q9F
   8:     0x7fdef1e344fa - middle::infer::InferCtxt<'a, 'tcx>::closure_type::hb9fca2654a1e5eebd1C
   9:     0x7fdef1eafd38 - middle::traits::select::SelectionContext<'cx, 'tcx>::closure_trait_ref_unnormalized::haf9984e1bd3a2127ImX
  10:     0x7fdef1d8d259 - middle::traits::select::SelectionContext<'cx, 'tcx>::select::hb6b9ab80b7d40addudU
  11:     0x7fdef1e942f3 - middle::traits::fulfill::process_predicate::h777636d2b6e7bc0dx5R
  12:     0x7fdef1e92c81 - middle::traits::fulfill::FulfillmentContext<'tcx>::select::h2760b340d700acc6ZYR
  13:     0x7fdef1e927d7 - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::hddcd4049e7010152tXR
  14:     0x7fdef1d38e23 - middle::traits::fulfill::FulfillmentContext<'tcx>::select_all_or_error::h4c3a89434e3357a6SVR
  15:     0x7fdef1e3359f - middle::traits::type_known_to_meet_builtin_bound::h1b4c4c37c2c4a2e0D3Y
  16:     0x7fdef1ee1c0b - middle::ty::util::ty..TyS<'tcx>::impls_bound::h02e3d047f5e01c50FW4
  17:     0x7fdef1e3372f - middle::ty::util::ty..TyS<'tcx>::moves_by_default::hb1722bfd58f33277WY4
  18:     0x7fdef1da6df2 - middle::expr_use_visitor::copy_or_move::h420c1a217b76bfa95Nr
  19:     0x7fdef1d34e66 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'a, 'tcx>::consume_expr::hdc82c412b9ba9053snq
  20:     0x7fdef1d7f394 - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'a, 'tcx>::walk_expr::hc7978fbe900003fdLvq
  21:     0x7fdef1d34eae - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'a, 'tcx>::consume_expr::hdc82c412b9ba9053snq
  22:     0x7fdef1d3660a - middle::expr_use_visitor::ExprUseVisitor<'d, 't, 'a, 'tcx>::walk_fn::h422f97948c1a8175Lhq
  23:     0x7fdef2b618dd - check::upvar::AdjustBorrowKind<'a, 'tcx>.Visitor<'v>::visit_fn::h76010959033c9b35Cbk
  24:     0x7fdef2b61550 - visit::walk_expr::h16181555174029332073
  25:     0x7fdef2b6124e - visit::walk_expr::h16181555174029332073
  26:     0x7fdef2ba58f5 - check::check_bare_fn::h1b9a831a51795dbcozp
  27:     0x7fdef2ba3310 - check::check_item_body::h223ccbb34dff59e3I0p
  28:     0x7fdef2c59cd2 - check_crate::h85ae42a95dc44b30GCE
  29:     0x7fdef4528c9e - driver::phase_3_run_analysis_passes::closure.21538
  30:     0x7fdef450b3bc - middle::ty::context::ctxt<'tcx>::create_and_enter::h14072355153472622424
  31:     0x7fdef4506b71 - driver::phase_3_run_analysis_passes::h5404249183138524855
  32:     0x7fdef44e74c3 - driver::compile_input::h813f6e216bee01860ba
  33:     0x7fdef464d02b - run_compiler::heebf093ad18f383a3qc
  34:     0x7fdef464a896 - boxed::F.FnBox<A>::call_box::h5441627487340085045
  35:     0x7fdef464a1a4 - sys_common::unwind::try::try_fn::h12996996568669864182
  36:     0x7fdef4008038 - __rust_try
  37:     0x7fdef3ffc832 - sys_common::unwind::try::inner_try::hc22680ca31a93181Dbs
  38:     0x7fdef464a33e - boxed::F.FnBox<A>::call_box::h4646831150340203223
  39:     0x7fdef4010233 - sys::thread::Thread::new::thread_start::h4012f549bc8d9354dGw
  40:     0x7fdeed5910a3 - start_thread
  41:     0x7fdef3c9106c - clone
  42:                0x0 - <unknown>

I compiled with rustc main.rs

Meta

rustc 1.5.0-nightly (6e5a325 2015-09-19)
binary: rustc
commit-hash: 6e5a325
commit-date: 2015-09-19
host: x86_64-unknown-linux-gnu
release: 1.5.0-nightly

[Stebalien]

Reduced test case:

// Using F directly causes it to compile.
struct A<F: FnOnce()>(F::Output);
struct B<F: FnOnce()>(A<F>);

// Removing Option causes it to compile.
fn foo<F: FnOnce()>(f: F) -> Option<B<F>> {
    panic!()
}

fn main() {
    || foo(||());
}

[arielb1]

This is a 1.3-1.4 regression.

I accidentally caused it in 9b75a2b.

[alexcrichton]

triage: I-nominated

[nikomatsakis]

triage: P-medium