bjoernager/rust
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Point out if a local trait has no implementations

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This commit is contained in:
Michael Goulet 2023-09-10 03:33:07 +00:00
parent 26f4b72724
commit 30e6cea0ae
63 changed files with 658 additions and 6 deletions
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2
compiler/rustc_trait_selection/messages.ftl
View file

@ -40,5 +40,7 @@ trait_selection_no_value_in_rustc_on_unimplemented = this attribute must have a
.label = expected value here
.note = eg `#[rustc_on_unimplemented(message="foo")]`
trait_selection_trait_has_no_impls = this trait has no implementations, consider adding one
trait_selection_ty_alias_overflow = in case this is a recursive type alias, consider using a struct, enum, or union instead
trait_selection_unable_to_construct_constant_value = unable to construct a constant value for the unevaluated constant {$unevaluated}

24
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View file

@ -3009,10 +3009,10 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
// Try to report a help message
if is_fn_trait
&& let Ok((implemented_kind, params)) = self.type_implements_fn_trait(
obligation.param_env,
trait_ref.self_ty(),
trait_predicate.skip_binder().polarity,
)
obligation.param_env,
trait_ref.self_ty(),
trait_predicate.skip_binder().polarity,
)
{
self.add_help_message_for_fn_trait(trait_ref, err, implemented_kind, params);
} else if !trait_ref.has_non_region_infer()
@ -3031,6 +3031,15 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
None,
obligation.cause.body_id,
);
} else if trait_ref.def_id().is_local()
&& self.tcx.trait_impls_of(trait_ref.def_id()).is_empty()
&& !self.tcx.trait_is_auto(trait_ref.def_id())
&& !self.tcx.trait_is_alias(trait_ref.def_id())
{
err.span_help(
self.tcx.def_span(trait_ref.def_id()),
crate::fluent_generated::trait_selection_trait_has_no_impls,
);
} else if !suggested && !unsatisfied_const {
// Can't show anything else useful, try to find similar impls.
let impl_candidates = self.find_similar_impl_candidates(*trait_predicate);
@ -3041,7 +3050,12 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
err,
true,
) {
self.report_similar_impl_candidates_for_root_obligation(&obligation, *trait_predicate, body_def_id, err);
self.report_similar_impl_candidates_for_root_obligation(
&obligation,
*trait_predicate,
body_def_id,
err,
);
}
self.suggest_convert_to_slice(