})
}
}
+
impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
fn report_fulfillment_errors(
&self,
let mut suggested =
self.suggest_dereferences(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_fn_call(&obligation, &mut err, trait_predicate);
+ let impl_candidates = self.find_similar_impl_candidates(trait_predicate);
+ suggested = if let &[cand] = &impl_candidates[..] {
+ let cand = cand.trait_ref;
+ if let (ty::FnPtr(_), ty::FnDef(..)) =
+ (cand.self_ty().kind(), trait_ref.self_ty().skip_binder().kind())
+ {
+ err.span_suggestion(
+ span.shrink_to_hi(),
+ format!(
+ "the trait `{}` is implemented for fn pointer `{}`, try casting using `as`",
+ cand.print_only_trait_path(),
+ cand.self_ty(),
+ ),
+ format!(" as {}", cand.self_ty()),
+ Applicability::MaybeIncorrect,
+ );
+ true
+ } else {
+ false
+ }
+ } else {
+ false
+ } || suggested;
suggested |=
self.suggest_remove_reference(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_semicolon_removal(
candidates.sort();
candidates.dedup();
let len = candidates.len();
- if candidates.len() == 0 {
+ if candidates.is_empty() {
return false;
}
- if candidates.len() == 1 {
- let ty_desc = match candidates[0].self_ty().kind() {
- ty::FnPtr(_) => Some("fn pointer"),
- _ => None,
- };
- let the_desc = match ty_desc {
- Some(desc) => format!(" implemented for {} `", desc),
- None => " implemented for `".to_string(),
- };
+ if let &[cand] = &candidates[..] {
+ let (desc, mention_castable) =
+ match (cand.self_ty().kind(), trait_ref.self_ty().skip_binder().kind()) {
+ (ty::FnPtr(_), ty::FnDef(..)) => {
+ (" implemented for fn pointer `", ", cast using `as`")
+ }
+ (ty::FnPtr(_), _) => (" implemented for fn pointer `", ""),
+ _ => (" implemented for `", ""),
+ };
err.highlighted_help(vec![
- (
- format!("the trait `{}` ", candidates[0].print_only_trait_path()),
- Style::NoStyle,
- ),
+ (format!("the trait `{}` ", cand.print_only_trait_path()), Style::NoStyle),
("is".to_string(), Style::Highlight),
- (the_desc, Style::NoStyle),
- (candidates[0].self_ty().to_string(), Style::Highlight),
+ (desc.to_string(), Style::NoStyle),
+ (cand.self_ty().to_string(), Style::Highlight),
("`".to_string(), Style::NoStyle),
+ (mention_castable.to_string(), Style::NoStyle),
]);
return true;
}