error: internal compiler error: unexpected panic #43774
Description
So I was messing around with iterators and created this horrific creature while struggling with shuffling around lifetimes and borrows:
fn prepare_async_listen<'a> (listener: &TcpListener) -> Result<impl Fn(&TcpListener) -> Result<Box<impl Iterator<Item=&TcpStream> + 'a>>> {
let poll = Poll::new()
.chain_err(|| "couldn't create poll")?;
poll.register(listener, Token(0), Ready::readable() | Ready::writable(), PollOpt::edge())
.chain_err(|| "couldn't register listener on poll")?;
Ok(move |listener: &TcpListener| {
let mut events = Events::with_capacity(1024);
poll.poll(&mut events, Some(Duration::from_millis(100)))
.chain_err(|| "polling failed")?;
Ok(Box::new(events.iter().map(|_| &listener.accept().unwrap().0)))
})
}
let listener = TcpListener::bind(&socket)
.chain_err(|| "listener couldn't bind socket")?;
let async_listen = prepare_async_listen(&listener)?;
while !should_die.get() {
trace_labeled_error!( format!("{} listener encountered a problem", desc), {
for stream in async_listen(&listener)? {
tx.send(stream_type(stream))
.chain_err(|| "sending stream to core channel failed")?;
};
});
};The compiler seemed so confused that it let me proceed with it and everything broke. This is the backtrace:
thread 'rustc' panicked at 'assertion failed: match *region { ty::ReLateBound(..) => false, _ => true, }', /checkout/src/librustc/infer/higher_ranked/mod.rs:493:8
stack backtrace:
0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at /checkout/src/libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at /checkout/src/libstd/sys_common/backtrace.rs:60
at /checkout/src/libstd/panicking.rs:380
3: std::panicking::default_hook
at /checkout/src/libstd/panicking.rs:390
4: std::panicking::rust_panic_with_hook
at /checkout/src/libstd/panicking.rs:611
5: std::panicking::begin_panic_new
6: rustc::infer::higher_ranked::fold_regions_in::{{closure}}
7: rustc::ty::fold::TypeFolder::fold_ty
8: rustc::infer::InferCtxt::match_poly_projection_predicate
9: rustc::traits::project::confirm_param_env_candidate
10: rustc::traits::project::confirm_candidate
11: rustc::traits::project::opt_normalize_projection_type
12: rustc::traits::project::normalize_projection_type
13: <rustc::traits::project::AssociatedTypeNormalizer<'a, 'b, 'gcx, 'tcx> as rustc::ty::fold::TypeFolder<'gcx, 'tcx>>::fold_ty
14: rustc::traits::project::opt_normalize_projection_type
15: rustc::traits::project::normalize_projection_type
16: <rustc::traits::project::AssociatedTypeNormalizer<'a, 'b, 'gcx, 'tcx> as rustc::ty::fold::TypeFolder<'gcx, 'tcx>>::fold_ty
17: rustc::traits::project::opt_normalize_projection_type
18: rustc::traits::project::poly_project_and_unify_type::{{closure}}
19: rustc::traits::project::poly_project_and_unify_type
20: <rustc::traits::fulfill::FulfillProcessor<'a, 'b, 'gcx, 'tcx> as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
21: rustc::traits::fulfill::FulfillmentContext::select
22: rustc::traits::fulfill::FulfillmentContext::select_where_possible
23: rustc_typeck::check::FnCtxt::select_obligations_where_possible
24: rustc_typeck::check::FnCtxt::check_argument_types
25: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::confirm_builtin_call
26: rustc_typeck::check::FnCtxt::check_expr_kind
27: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
28: rustc_typeck::check::FnCtxt::check_expr_meets_expectation_or_error
29: rustc_typeck::check::FnCtxt::check_expr_kind
30: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
31: rustc_typeck::check::FnCtxt::check_decl_local
32: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
33: rustc_typeck::check::FnCtxt::check_block_with_expected
34: rustc_typeck::check::FnCtxt::check_expr_kind
35: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
36: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
37: rustc_typeck::check::FnCtxt::check_block_with_expected
38: rustc_typeck::check::FnCtxt::check_expr_kind
39: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
40: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
41: rustc_typeck::check::FnCtxt::check_block_with_expected
42: rustc_typeck::check::FnCtxt::check_expr_kind
43: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
44: rustc_typeck::check::FnCtxt::check_return_expr
45: rustc_typeck::check::check_fn
46: rustc_typeck::check::closure::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::check_closure
47: rustc_typeck::check::FnCtxt::check_expr_kind
48: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
49: rustc_typeck::check::FnCtxt::check_expr_kind
50: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
51: rustc_typeck::check::FnCtxt::check_expr_kind
52: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
53: rustc_typeck::check::FnCtxt::check_argument_types
54: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::confirm_builtin_call
55: rustc_typeck::check::FnCtxt::check_expr_kind
56: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
57: rustc_typeck::check::FnCtxt::check_expr_meets_expectation_or_error
58: rustc_typeck::check::FnCtxt::check_expr_kind
59: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
60: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
61: rustc_typeck::check::FnCtxt::check_block_with_expected
62: rustc_typeck::check::FnCtxt::check_expr_kind
63: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
64: rustc_typeck::check::FnCtxt::check_return_expr
65: rustc_typeck::check::check_fn
66: rustc_typeck::check::closure::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::check_closure
67: rustc_typeck::check::FnCtxt::check_expr_kind
68: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
69: rustc_typeck::check::FnCtxt::check_expr_kind
70: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
71: rustc_typeck::check::FnCtxt::check_expr_kind
72: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
73: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
74: rustc_typeck::check::FnCtxt::check_block_with_expected
75: rustc_typeck::check::FnCtxt::check_expr_kind
76: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
77: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
78: rustc_typeck::check::FnCtxt::check_block_with_expected
79: rustc_typeck::check::FnCtxt::check_expr_kind
80: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
81: rustc_typeck::check::FnCtxt::check_block_with_expected::{{closure}}
82: rustc_typeck::check::FnCtxt::check_block_with_expected
83: rustc_typeck::check::FnCtxt::check_expr_kind
84: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
85: rustc_typeck::check::FnCtxt::check_return_expr
86: rustc_typeck::check::check_fn
87: rustc_typeck::check::closure::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::check_closure
88: rustc_typeck::check::FnCtxt::check_expr_kind
89: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
90: rustc_typeck::check::FnCtxt::check_expr_kind
91: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
92: rustc_typeck::check::FnCtxt::check_expr_kind
93: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
94: rustc_typeck::check::FnCtxt::check_argument_types
95: rustc_typeck::check::callee::<impl rustc_typeck::check::FnCtxt<'a, 'gcx, 'tcx>>::confirm_builtin_call
96: rustc_typeck::check::FnCtxt::check_expr_kind
97: rustc_typeck::check::FnCtxt::check_expr_with_expectation_and_lvalue_pref
98: rustc_typeck::check::FnCtxt::check_expr_meets_expectation_or_error
99: rustc_typeck::check::FnCtxt::check_expr_kind
It told me to report this error so I did but honestly any help with getting that code above to compile would be appreciated because that backtrace is way over my skill level and I don't know what to do with it.
Some meta:
rustc 1.20.0-nightly (9b85e1cfa 2017-07-07)
binary: rustc
commit-hash: 9b85e1cfa5aa2aaa4b5df4359a023ad793983ffc
commit-date: 2017-07-07
host: x86_64-unknown-linux-gnu
release: 1.20.0-nightly
LLVM version: 4.0
Built using mio crate and #![feature(conservative_impl_trait)]