ICE with async + HRTB + Closures

[estebank]

Given the following:

#![feature(unboxed_closures)]

async fn wrapper<F>(f: F) 
where for<'a> F: FnOnce<(&'a mut i32,)>,
    for<'a> <F as FnOnce<(&'a mut i32,)>>::Output: Future<Output=()> + 'a
{
    let mut i = 41;
    f(&mut i).await;
}

async fn add_one(i: &mut i32) {
    *i = *i + 1;
}

Triggers an ICE

Backtrace

error: internal compiler error: compiler/rustc_mir/src/borrow_check/universal_regions.rs:768:36: cannot convert `RePlaceholder(Placeholder { universe: U4, name: BrNamed(DefId(0:8 ~ playground[beb8]::wrapper::'a#1), 'a) })` to a region vid

thread 'rustc' panicked at 'Box<Any>', compiler/rustc_errors/src/lib.rs:958:9
stack backtrace:
   0: std::panicking::begin_panic
   1: rustc_errors::HandlerInner::bug
   2: rustc_errors::Handler::bug
   3: rustc_middle::util::bug::opt_span_bug_fmt::{{closure}}
   4: rustc_middle::ty::context::tls::with_opt::{{closure}}
   5: rustc_middle::ty::context::tls::with_opt
   6: rustc_middle::util::bug::opt_span_bug_fmt
   7: rustc_middle::util::bug::bug_fmt
   8: rustc_mir::borrow_check::universal_regions::UniversalRegionIndices::to_region_vid::{{closure}}
   9: rustc_mir::borrow_check::universal_regions::UniversalRegionIndices::to_region_vid
  10: rustc_mir::borrow_check::region_infer::RegionInferenceContext::eval_verify_bound
  11: rustc_mir::borrow_check::region_infer::RegionInferenceContext::eval_verify_bound
  12: rustc_mir::borrow_check::region_infer::RegionInferenceContext::solve
  13: rustc_mir::borrow_check::nll::compute_regions
  14: rustc_mir::borrow_check::do_mir_borrowck
  15: rustc_infer::infer::InferCtxtBuilder::enter
  16: rustc_mir::borrow_check::mir_borrowck
  17: core::ops::function::FnOnce::call_once
  18: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::mir_borrowck>::compute
  19: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  20: rustc_data_structures::stack::ensure_sufficient_stack
  21: rustc_query_system::query::plumbing::get_query_impl
  22: rustc_typeck::collect::type_of::type_of
  23: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::type_of>::compute
  24: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  25: rustc_data_structures::stack::ensure_sufficient_stack
  26: rustc_query_system::query::plumbing::get_query_impl
  27: rustc_typeck::check::check::check_item_type
  28: rustc_middle::hir::map::Map::visit_item_likes_in_module
  29: rustc_typeck::check::check::check_mod_item_types
  30: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::check_mod_item_types>::compute
  31: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  32: rustc_data_structures::stack::ensure_sufficient_stack
  33: rustc_query_system::query::plumbing::get_query_impl
  34: rustc_query_system::query::plumbing::ensure_query_impl
  35: rustc_session::utils::<impl rustc_session::session::Session>::time
  36: rustc_typeck::check_crate
  37: rustc_interface::passes::analysis
  38: rustc_middle::ty::query::<impl rustc_query_system::query::config::QueryAccessors<rustc_middle::ty::context::TyCtxt> for rustc_middle::ty::query::queries::analysis>::compute
  39: rustc_query_system::dep_graph::graph::DepGraph<K>::with_task_impl
  40: rustc_data_structures::stack::ensure_sufficient_stack
  41: rustc_query_system::query::plumbing::get_query_impl
  42: rustc_interface::passes::QueryContext::enter
  43: rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter
  44: rustc_span::with_source_map
  45: scoped_tls::ScopedKey<T>::set

Derived from https://www.reddit.com/r/rust/comments/jvqorj/hrtb_with_async_functions/

[SNCPlay42]

This looks like #76168.

[estebank]

It absolutely does.