diff --git a/compiler/rustc_hir_analysis/src/astconv/errors.rs b/compiler/rustc_hir_analysis/src/astconv/errors.rs index 6082d446979..ed4dde419c4 100644 --- a/compiler/rustc_hir_analysis/src/astconv/errors.rs +++ b/compiler/rustc_hir_analysis/src/astconv/errors.rs @@ -110,16 +110,22 @@ pub(crate) fn complain_about_assoc_type_not_found( { // The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a // valid span, so we point at the whole path segment instead. - let span = if assoc_name.span != DUMMY_SP { assoc_name.span } else { span }; + let is_dummy = assoc_name.span == DUMMY_SP; + let mut err = struct_span_err!( self.tcx().sess, - span, + if is_dummy { span } else { assoc_name.span }, E0220, "associated type `{}` not found for `{}`", assoc_name, ty_param_name ); + if is_dummy { + err.span_label(span, format!("associated type `{assoc_name}` not found")); + return err.emit(); + } + let all_candidate_names: Vec<_> = all_candidates() .flat_map(|r| self.tcx().associated_items(r.def_id()).in_definition_order()) .filter_map(|item| { @@ -131,10 +137,9 @@ pub(crate) fn complain_about_assoc_type_not_found( }) .collect(); - if let (Some(suggested_name), true) = ( - find_best_match_for_name(&all_candidate_names, assoc_name.name, None), - assoc_name.span != DUMMY_SP, - ) { + if let Some(suggested_name) = + find_best_match_for_name(&all_candidate_names, assoc_name.name, None) + { err.span_suggestion( assoc_name.span, "there is an associated type with a similar name", @@ -172,10 +177,9 @@ pub(crate) fn complain_about_assoc_type_not_found( }) .collect(); - if let (Some(suggested_name), true) = ( - find_best_match_for_name(&wider_candidate_names, assoc_name.name, None), - assoc_name.span != DUMMY_SP, - ) { + if let Some(suggested_name) = + find_best_match_for_name(&wider_candidate_names, assoc_name.name, None) + { if let [best_trait] = visible_traits .iter() .filter(|trait_def_id| { @@ -197,7 +201,28 @@ pub(crate) fn complain_about_assoc_type_not_found( } } - err.span_label(span, format!("associated type `{assoc_name}` not found")); + // If we still couldn't find any associated type, and only one associated type exists, + // suggests using it. + + if all_candidate_names.len() == 1 { + // this should still compile, except on `#![feature(associated_type_defaults)]` + // where it could suggests `type A = Self::A`, thus recursing infinitely + let applicability = if self.tcx().features().associated_type_defaults { + Applicability::Unspecified + } else { + Applicability::MaybeIncorrect + }; + + err.span_suggestion( + assoc_name.span, + format!("`{ty_param_name}` has the following associated type"), + all_candidate_names.first().unwrap().to_string(), + applicability, + ); + } else { + err.span_label(assoc_name.span, format!("associated type `{assoc_name}` not found")); + } + err.emit() } diff --git a/tests/ui/associated-types/issue-23595-2.stderr b/tests/ui/associated-types/issue-23595-2.stderr index dded673f6ee..73effa9f955 100644 --- a/tests/ui/associated-types/issue-23595-2.stderr +++ b/tests/ui/associated-types/issue-23595-2.stderr @@ -2,7 +2,7 @@ error[E0220]: associated type `anything_here_kills_it` not found for `Self` --> $DIR/issue-23595-2.rs:6:22 | LL | type B = C; - | ^^^^^^^^^^^^^^^^^^^^^^ associated type `anything_here_kills_it` not found + | ^^^^^^^^^^^^^^^^^^^^^^ help: `Self` has the following associated type: `B` error: aborting due to previous error diff --git a/tests/ui/error-codes/E0220.stderr b/tests/ui/error-codes/E0220.stderr index 11763ce788d..e03eadacae4 100644 --- a/tests/ui/error-codes/E0220.stderr +++ b/tests/ui/error-codes/E0220.stderr @@ -2,7 +2,7 @@ error[E0220]: associated type `F` not found for `Trait` --> $DIR/E0220.rs:5:22 | LL | type Foo = dyn Trait; - | ^ associated type `F` not found + | ^ help: `Trait` has the following associated type: `Bar` error[E0191]: the value of the associated type `Bar` (from trait `Trait`) must be specified --> $DIR/E0220.rs:5:16 diff --git a/tests/ui/lifetimes/issue-95023.stderr b/tests/ui/lifetimes/issue-95023.stderr index 5b93eff8614..6361d8ad30b 100644 --- a/tests/ui/lifetimes/issue-95023.stderr +++ b/tests/ui/lifetimes/issue-95023.stderr @@ -36,7 +36,7 @@ error[E0220]: associated type `B` not found for `Self` --> $DIR/issue-95023.rs:6:44 | LL | fn foo(&self) -> Self::B<{N}>; - | ^ associated type `B` not found + | ^ help: `Self` has the following associated type: `Output` error: aborting due to 5 previous errors