bjoernager/rust
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Suggest creating unary tuples

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This commit is contained in:
mejrs 2024-11-04 12:06:19 +01:00
parent 1e4f10ba64
commit 5a48fe2c20
11 changed files with 155 additions and 0 deletions
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4
compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
View file

@ -466,6 +466,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
}
self.try_to_add_help_message(
&root_obligation,
&obligation,
leaf_trait_predicate,
&mut err,
@ -2428,6 +2429,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
fn try_to_add_help_message(
&self,
root_obligation: &PredicateObligation<'tcx>,
obligation: &PredicateObligation<'tcx>,
trait_predicate: ty::PolyTraitPredicate<'tcx>,
err: &mut Diag<'_>,
@ -2511,6 +2513,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
impl_candidates.as_slice(),
span,
);
self.suggest_tuple_wrapping(err, root_obligation, obligation);
}
}

35
compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
View file

@ -4436,6 +4436,41 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
}
}
/// If the type failed selection but the trait is implemented for `(T,)`, suggest that the user
/// creates a unary tuple
///
/// This is a common gotcha when using libraries that emulate variadic functions with traits for tuples.
pub(super) fn suggest_tuple_wrapping(
&self,
err: &mut Diag<'_>,
root_obligation: &PredicateObligation<'tcx>,
obligation: &PredicateObligation<'tcx>,
) {
let ObligationCauseCode::FunctionArg { arg_hir_id, .. } = obligation.cause.code() else {
return;
};
let Some(root_pred) = root_obligation.predicate.as_trait_clause() else { return };
let trait_ref = root_pred.map_bound(|root_pred| {
root_pred
.trait_ref
.with_self_ty(self.tcx, Ty::new_tup(self.tcx, &[root_pred.trait_ref.self_ty()]))
});
let obligation =
Obligation::new(self.tcx, obligation.cause.clone(), obligation.param_env, trait_ref);
if self.predicate_must_hold_modulo_regions(&obligation) {
let arg_span = self.tcx.hir().span(*arg_hir_id);
err.multipart_suggestion_verbose(
format!("use a unary tuple instead"),
vec![(arg_span.shrink_to_lo(), "(".into()), (arg_span.shrink_to_hi(), ",)".into())],
Applicability::MaybeIncorrect,
);
}
}
pub(super) fn explain_hrtb_projection(
&self,
diag: &mut Diag<'_>,