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Support {async closure}: Fn in new solver

This commit is contained in:
Michael Goulet 2024-02-26 23:43:10 +00:00
parent b6e4299415
commit a6727bad88
3 changed files with 101 additions and 3 deletions

View file

@ -281,7 +281,79 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
}
// Coroutine-closures don't implement `Fn` traits the normal way.
ty::CoroutineClosure(..) => Err(NoSolution),
// Instead, they always implement `FnOnce`, but only implement
// `FnMut`/`Fn` if they capture no upvars, since those may borrow
// from the closure.
ty::CoroutineClosure(def_id, args) => {
let args = args.as_coroutine_closure();
let kind_ty = args.kind_ty();
let sig = args.coroutine_closure_sig().skip_binder();
let coroutine_ty = if let Some(closure_kind) = kind_ty.to_opt_closure_kind() {
if !closure_kind.extends(goal_kind) {
return Err(NoSolution);
}
// If `Fn`/`FnMut`, we only implement this goal if we
// have no captures.
let no_borrows = match args.tupled_upvars_ty().kind() {
ty::Tuple(tys) => tys.is_empty(),
ty::Error(_) => false,
_ => bug!("tuple_fields called on non-tuple"),
};
if closure_kind != ty::ClosureKind::FnOnce && !no_borrows {
return Err(NoSolution);
}
sig.to_coroutine_given_kind_and_upvars(
tcx,
args.parent_args(),
tcx.coroutine_for_closure(def_id),
goal_kind,
// No captures by ref, so this doesn't matter.
tcx.lifetimes.re_static,
args.tupled_upvars_ty(),
args.coroutine_captures_by_ref_ty(),
)
} else {
// Closure kind is not yet determined, so we return ambiguity unless
// the expected kind is `FnOnce` as that is always implemented.
if goal_kind != ty::ClosureKind::FnOnce {
return Ok(None);
}
let async_fn_kind_trait_def_id =
tcx.require_lang_item(LangItem::AsyncFnKindHelper, None);
let upvars_projection_def_id = tcx
.associated_items(async_fn_kind_trait_def_id)
.filter_by_name_unhygienic(sym::Upvars)
.next()
.unwrap()
.def_id;
let tupled_upvars_ty = Ty::new_projection(
tcx,
upvars_projection_def_id,
[
ty::GenericArg::from(kind_ty),
Ty::from_closure_kind(tcx, goal_kind).into(),
// No captures by ref, so this doesn't matter.
tcx.lifetimes.re_static.into(),
sig.tupled_inputs_ty.into(),
args.tupled_upvars_ty().into(),
args.coroutine_captures_by_ref_ty().into(),
],
);
sig.to_coroutine(
tcx,
args.parent_args(),
Ty::from_closure_kind(tcx, goal_kind),
tcx.coroutine_for_closure(def_id),
tupled_upvars_ty,
)
};
Ok(Some(args.coroutine_closure_sig().rebind((sig.tupled_inputs_ty, coroutine_ty))))
}
ty::Bool
| ty::Char