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Allow desugaring async fn in trait to compatible, concrete future types

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This commit is contained in:
Michael Goulet 2024-01-18 16:39:20 +00:00
parent ea37e8091f
commit 16cbdd0321
9 changed files with 15 additions and 77 deletions
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31
compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
View file

@ -74,7 +74,6 @@ fn check_method_is_structurally_compatible<'tcx>(
compare_generic_param_kinds(tcx, impl_m, trait_m, delay)?;
compare_number_of_method_arguments(tcx, impl_m, trait_m, delay)?;
compare_synthetic_generics(tcx, impl_m, trait_m, delay)?;
compare_asyncness(tcx, impl_m, trait_m, delay)?;
check_region_bounds_on_impl_item(tcx, impl_m, trait_m, delay)?;
Ok(())
}
@ -414,36 +413,6 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateBound<'_, 'tcx> {
}
}
fn compare_asyncness<'tcx>(
tcx: TyCtxt<'tcx>,
impl_m: ty::AssocItem,
trait_m: ty::AssocItem,
delay: bool,
) -> Result<(), ErrorGuaranteed> {
if tcx.asyncness(trait_m.def_id).is_async() {
match tcx.fn_sig(impl_m.def_id).skip_binder().skip_binder().output().kind() {
ty::Alias(ty::Opaque, ..) => {
// allow both `async fn foo()` and `fn foo() -> impl Future`
}
ty::Error(_) => {
// We don't know if it's ok, but at least it's already an error.
}
_ => {
return Err(tcx
.dcx()
.create_err(crate::errors::AsyncTraitImplShouldBeAsync {
span: tcx.def_span(impl_m.def_id),
method_name: trait_m.name,
trait_item_span: tcx.hir().span_if_local(trait_m.def_id),
})
.emit_unless(delay));
}
};
}
Ok(())
}
/// Given a method def-id in an impl, compare the method signature of the impl
/// against the trait that it's implementing. In doing so, infer the hidden types
/// that this method's signature provides to satisfy each return-position `impl Trait`

11
compiler/rustc_hir_analysis/src/errors.rs
View file

@ -166,17 +166,6 @@ pub struct LifetimesOrBoundsMismatchOnTrait {
pub ident: Ident,
}
#[derive(Diagnostic)]
#[diag(hir_analysis_async_trait_impl_should_be_async)]
pub struct AsyncTraitImplShouldBeAsync {
#[primary_span]
// #[label]
pub span: Span,
#[label(hir_analysis_trait_item_label)]
pub trait_item_span: Option<Span>,
pub method_name: Symbol,
}
#[derive(Diagnostic)]
#[diag(hir_analysis_drop_impl_on_wrong_item, code = E0120)]
pub struct DropImplOnWrongItem {