NLL impl_trait_in_bindings ICE

[DutchGhost]

#![feature(impl_trait_in_bindings)]
fn bug<'a, 'b, T>()
where
    'a: 'b,
{
    let f: impl Fn(&'a T) -> &'b T = |x| x;
}


fn main() {}

Backtrace:

thread 'rustc' panicked at 'assertion failed: self.universal_regions.is_universal_region(shorter)', src/librustc_mir/borrow_check/nll/type_check/free_region_relations.rs:335:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:70
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:200
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:215
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:482
   6: std::panicking::begin_panic
   7: <rustc_mir::borrow_check::nll::type_check::free_region_relations::UniversalRegionRelations<'tcx> as rustc::infer::outlives::free_region_map::FreeRegionRelations<'tcx>>::sub_free_regions
   8: rustc::infer::InferCtxt::commit_if_ok
   9: <rustc::traits::query::type_op::custom::CustomTypeOp<F, G> as rustc::traits::query::type_op::TypeOp<'gcx, 'tcx>>::fully_perform
  10: rustc_mir::borrow_check::nll::type_check::TypeChecker::eq_opaque_type_and_type
  11: rustc_mir::borrow_check::nll::type_check::TypeChecker::check_stmt
  12: rustc_mir::borrow_check::nll::type_check::TypeChecker::typeck_mir
  13: rustc_mir::borrow_check::nll::type_check::type_check
  14: rustc_mir::borrow_check::do_mir_borrowck
  15: rustc::ty::context::GlobalCtxt::enter_local
  16: rustc_mir::borrow_check::mir_borrowck
  17: rustc::ty::query::__query_compute::mir_borrowck
  18: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::mir_borrowck<'tcx>>::compute
  19: rustc::dep_graph::graph::DepGraph::with_task_impl
  20: <rustc::ty::query::plumbing::JobOwner<'a, 'tcx, Q>>::start
  21: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
  22: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::try_get_with
  23: rustc::ty::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::par_body_owners
  24: rustc::util::common::time
  25: <std::thread::local::LocalKey<T>>::with
  26: rustc::ty::context::TyCtxt::create_and_enter
  27: rustc_driver::driver::compile_input
  28: rustc_driver::run_compiler_with_pool
  29: <scoped_tls::ScopedKey<T>>::set
  30: rustc_driver::run_compiler
  31: <scoped_tls::ScopedKey<T>>::set
query stack during panic:
#0 [mir_borrowck] processing `bug`
end of query stack

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

note: rustc 1.33.0-nightly (60e825389 2018-12-28) running on x86_64-unknown-linux-gnu

note: compiler flags: -C opt-level=3 -C codegen-units=1 --crate-type bin

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `playground`.

https://play.rust-lang.org/?version=nightly&mode=release&edition=2018&gist=fed15c3173e52cba9875b50dace18c00

2015's Edition compiles fine (without NLL), 2018 ICE's

[Alexendoo]

Fixed by #67681