ICE(async_await,futures_api,await_macro,generators): cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(2)) <= '_#1r

I tried to write a generic `async` wrapper for something similar to `tokio_reactor::PollEvented` that calls `poll_...`, `clear_...` and `yield` depending on the `io::Result` of an operation and got the error mentioned in the subject.

I managed to reduce the code triggering it to this:

```rust
#![feature(async_await,futures_api,await_macro,generators)]

pub struct Foo;

impl Foo {
	async fn with<'a, F, R>(&'a self, f: F) -> R
	where
		F: Fn() -> R + 'a,
	{
		loop {
			match f() {
				_ => yield,
			}
		}
	}

	pub async fn run<'a>(&'a self, data: &'a [u8])
	{
		await!(self.with(move || {
			println!("{:p}", data);
		}))
	}
}

fn main() {
}
```

([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=b33785b77fd4d07e973d95a7068f16b6))

Probably related to #53989.

Full error message:

```
error: internal compiler error: src/librustc/infer/region_constraints/mod.rs:683: cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(2)) <= '_#1r

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:538:9
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:72
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:60
             at src/libstd/panicking.rs:210
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:225
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:492
   6: std::panicking::begin_panic
   7: rustc_errors::Handler::span_bug
   8: rustc::util::bug::opt_span_bug_fmt::{{closure}}
   9: rustc::ty::context::tls::with_opt::{{closure}}
  10: rustc::ty::context::tls::with_context_opt
  11: rustc::ty::context::tls::with_opt
  12: rustc::util::bug::opt_span_bug_fmt
  13: rustc::util::bug::span_bug_fmt
  14: rustc::infer::region_constraints::RegionConstraintCollector::make_subregion
  15: rustc::infer::region_constraints::RegionConstraintCollector::make_eqregion
  16: <rustc::infer::equate::Equate<'combine, 'infcx, 'gcx, 'tcx> as rustc::ty::relate::TypeRelation<'infcx, 'gcx, 'tcx>>::regions
  17: rustc::ty::relate::super_relate_tys
  18: rustc::infer::combine::<impl rustc::infer::InferCtxt<'infcx, 'gcx, 'tcx>>::super_combine_tys
  19: <rustc::infer::equate::Equate<'combine, 'infcx, 'gcx, 'tcx> as rustc::ty::relate::TypeRelation<'infcx, 'gcx, 'tcx>>::tys
  20: <rustc::ty::subst::Kind<'tcx> as rustc::ty::relate::Relate<'tcx>>::relate
  21: <smallvec::SmallVec<A> as core::iter::traits::FromIterator<<A as smallvec::Array>::Item>>::from_iter
  22: <I as rustc::ty::context::InternAs<[T], R>>::intern_with
  23: <rustc::ty::sty::TraitRef<'tcx> as rustc::ty::relate::Relate<'tcx>>::relate
  24: rustc::infer::InferCtxt::commit_if_ok
  25: rustc::traits::select::SelectionContext::match_impl
  26: rustc::infer::InferCtxt::probe
  27: rustc::ty::trait_def::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::for_each_relevant_impl
  28: rustc::traits::select::SelectionContext::assemble_candidates_from_impls
  29: rustc::traits::select::SelectionContext::assemble_candidates
  30: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  31: rustc::ty::context::tls::with_context
  32: rustc::dep_graph::graph::DepGraph::with_anon_task
  33: rustc::traits::select::SelectionContext::candidate_from_obligation
  34: rustc::traits::select::SelectionContext::evaluate_stack
  35: rustc::ty::context::tls::with_context
  36: rustc::dep_graph::graph::DepGraph::with_anon_task
  37: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  38: rustc::infer::InferCtxt::probe
  39: rustc::traits::select::SelectionContext::evaluate_stack
  40: rustc::ty::context::tls::with_context
  41: rustc::dep_graph::graph::DepGraph::with_anon_task
  42: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  43: rustc::infer::InferCtxt::probe
  44: rustc::traits::select::SelectionContext::evaluate_stack
  45: rustc::ty::context::tls::with_context
  46: rustc::dep_graph::graph::DepGraph::with_anon_task
  47: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  48: rustc::infer::InferCtxt::probe
  49: rustc::traits::select::SelectionContext::evaluate_stack
  50: rustc::ty::context::tls::with_context
  51: rustc::dep_graph::graph::DepGraph::with_anon_task
  52: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  53: rustc::infer::InferCtxt::probe
  54: rustc::traits::select::SelectionContext::evaluate_stack
  55: rustc::ty::context::tls::with_context
  56: rustc::dep_graph::graph::DepGraph::with_anon_task
  57: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  58: rustc::infer::InferCtxt::probe
  59: rustc::traits::select::SelectionContext::evaluate_stack
  60: rustc::ty::context::tls::with_context
  61: rustc::dep_graph::graph::DepGraph::with_anon_task
  62: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  63: rustc::infer::InferCtxt::probe
  64: rustc::traits::select::SelectionContext::evaluate_stack
  65: rustc::ty::context::tls::with_context
  66: rustc::dep_graph::graph::DepGraph::with_anon_task
  67: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  68: rustc::infer::InferCtxt::probe
  69: rustc::traits::select::SelectionContext::evaluate_stack
  70: rustc::ty::context::tls::with_context
  71: rustc::dep_graph::graph::DepGraph::with_anon_task
  72: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  73: rustc::infer::InferCtxt::probe
  74: rustc::traits::select::SelectionContext::evaluate_stack
  75: rustc::ty::context::tls::with_context
  76: rustc::dep_graph::graph::DepGraph::with_anon_task
  77: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  78: rustc::traits::select::SelectionContext::evaluate_obligation_recursively
  79: rustc::ty::context::tls::with_related_context
  80: rustc_traits::evaluate_obligation::evaluate_obligation
  81: rustc::ty::query::__query_compute::evaluate_obligation
  82: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::evaluate_obligation<'tcx>>::compute
  83: rustc::ty::context::tls::with_context
  84: rustc::dep_graph::graph::DepGraph::with_task_impl
  85: rustc::ty::context::tls::with_related_context
  86: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
  87: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::try_get_with
  88: rustc::traits::query::evaluate_obligation::<impl rustc::infer::InferCtxt<'cx, 'gcx, 'tcx>>::evaluate_obligation
  89: rustc::traits::query::evaluate_obligation::<impl rustc::infer::InferCtxt<'cx, 'gcx, 'tcx>>::evaluate_obligation_no_overflow
  90: rustc::traits::type_known_to_meet_bound
  91: rustc::ty::context::tls::with_related_context
  92: rustc::infer::InferCtxtBuilder::enter
  93: rustc::ty::util::is_freeze_raw
  94: rustc::ty::query::__query_compute::is_freeze_raw
  95: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::is_freeze_raw<'tcx>>::compute
  96: rustc::ty::context::tls::with_context
  97: rustc::dep_graph::graph::DepGraph::with_task_impl
  98: rustc::ty::context::tls::with_related_context
  99: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `[static generator@src/main.rs:18:2: 22:3 self:&Foo, data:&[u8] for<'r, 's, 't0> {impl std::future::Future, ()}]: std::marker::Freeze`
#1 [is_freeze_raw] computing whether `[static generator@src/main.rs:18:2: 22:3 self:&'a Foo, data:&'a [u8] for<'r, 's, 't0> {impl std::future::Future, ()}]` is freeze
#2 [mir_validated] processing `Foo::run::{{closure}}`
#3 [mir_borrowck] processing `Foo::run::{{closure}}`
end of query stack
error: aborting due to previous error


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

note: rustc 1.33.0-nightly (2d3e909e4 2018-12-22) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden
```

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ICE(async_await,futures_api,await_macro,generators): cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(2)) <= '_#1r #57084

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ICE(async_await,futures_api,await_macro,generators): cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(2)) <= '_#1r #57084

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