diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs | 41 |
1 files changed, 25 insertions, 16 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 69649e36178..5bab57ca56c 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -1432,20 +1432,18 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { ) -> bool { let span = obligation.cause.span; - let code = if let ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } = - obligation.cause.code() - { - parent_code - } else if let ObligationCauseCode::ItemObligation(_) - | ObligationCauseCode::ExprItemObligation(..) = obligation.cause.code() - { - obligation.cause.code() - } else if let ExpnKind::Desugaring(DesugaringKind::ForLoop) = - span.ctxt().outer_expn_data().kind - { - obligation.cause.code() - } else { - return false; + let code = match obligation.cause.code() { + ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } => parent_code, + c @ ObligationCauseCode::ItemObligation(_) + | c @ ObligationCauseCode::ExprItemObligation(..) => c, + c if matches!( + span.ctxt().outer_expn_data().kind, + ExpnKind::Desugaring(DesugaringKind::ForLoop) + ) => + { + c + } + _ => return false, }; // List of traits for which it would be nonsensical to suggest borrowing. @@ -4978,16 +4976,27 @@ pub(super) fn get_explanation_based_on_obligation<'tcx>( _ => None, }; + let pred = obligation.predicate; + let (_, base) = obligation.cause.code().peel_derives_with_predicate(); + let post = if let ty::PredicateKind::Clause(clause) = pred.kind().skip_binder() + && let ty::ClauseKind::Trait(pred) = clause + && let Some(base) = base + && base.skip_binder() != pred + { + format!(", which is required by `{base}`") + } else { + String::new() + }; match ty_desc { Some(desc) => format!( - "{}the trait `{}` is not implemented for {} `{}`", + "{}the trait `{}` is not implemented for {} `{}`{post}", pre_message, trait_predicate.print_modifiers_and_trait_path(), desc, tcx.short_ty_string(trait_ref.skip_binder().self_ty(), &mut None), ), None => format!( - "{}the trait `{}` is not implemented for `{}`", + "{}the trait `{}` is not implemented for `{}`{post}", pre_message, trait_predicate.print_modifiers_and_trait_path(), tcx.short_ty_string(trait_ref.skip_binder().self_ty(), &mut None), |