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No need to instantiate binder in confirm_async_closure_candidate

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This commit is contained in:
Michael Goulet 2024-11-02 03:10:31 +00:00
parent 7c7bb7dc01
commit c10fe34fb9
1 changed files with 3 additions and 9 deletions
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12
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@ -951,18 +951,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}); });
// We must additionally check that the return type impls `Future`. // We must additionally check that the return type impls `Future`.
// FIXME(async_closures): Investigate this before stabilization.
// We instantiate this binder eagerly because the `confirm_future_candidate`
// method doesn't support higher-ranked futures, which the `AsyncFn`
// traits expressly allow the user to write. To fix this correctly,
// we'd need to instantiate trait bounds before we get to selection,
// like the new trait solver does.
let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None); let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None);
let placeholder_output_ty = self.infcx.enter_forall_and_leak_universe(sig.output());
nested.push(obligation.with( nested.push(obligation.with(
tcx, tcx,
ty::TraitRef::new(tcx, future_trait_def_id, [placeholder_output_ty]), sig.output().map_bound(|output_ty| {
ty::TraitRef::new(tcx, future_trait_def_id, [output_ty])
}),
)); ));
(trait_ref, Ty::from_closure_kind(tcx, ty::ClosureKind::Fn)) (trait_ref, Ty::from_closure_kind(tcx, ty::ClosureKind::Fn))