Don't suppress lint type_alias_bounds for ty aliases containing inherent assoc tys

1 files changed, 11 insertions, 17 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 9ebada0fff3..40b336cd5ea 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1425,30 +1425,27 @@ impl TypeAliasBounds {
 
 impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
-        let hir::ItemKind::TyAlias(hir_ty, type_alias_generics) = &item.kind else { return };
+        let hir::ItemKind::TyAlias(hir_ty, generics) = &item.kind else { return };
 
-        // Bounds of lazy type aliases and TAITs are respected.
-        if cx.tcx.type_alias_is_lazy(item.owner_id) {
+        // There must not be a where clause.
+        if generics.predicates.is_empty() {
             return;
         }
 
-        let ty = cx.tcx.type_of(item.owner_id).skip_binder();
-        if ty.has_inherent_projections() {
-            // Bounds of type aliases that contain opaque types or inherent projections are
-            // respected. E.g: `type X = impl Trait;`, `type X = (impl Trait, Y);`, `type X =
-            // Type::Inherent;`.
+        // Bounds of lazy type aliases and TAITs are respected.
+        if cx.tcx.type_alias_is_lazy(item.owner_id) {
             return;
         }
 
-        // There must not be a where clause
-        if type_alias_generics.predicates.is_empty() {
-            return;
-        }
+        // NOTE(inherent_associated_types): While we currently do take some bounds in type
+        // aliases into consideration during IAT *selection*, we don't perform full use+def
+        // site wfchecking for such type aliases. Therefore TAB should still trigger.
+        // See also `tests/ui/associated-inherent-types/type-alias-bounds.rs`.
 
         let mut where_spans = Vec::new();
         let mut inline_spans = Vec::new();
         let mut inline_sugg = Vec::new();
-        for p in type_alias_generics.predicates {
+        for p in generics.predicates {
             let span = p.span();
             if p.in_where_clause() {
                 where_spans.push(span);
@@ -1469,10 +1466,7 @@ impl<'tcx> LateLintPass<'tcx> for TypeAliasBounds {
             cx.emit_span_lint(
                 TYPE_ALIAS_BOUNDS,
                 where_spans,
-                BuiltinTypeAliasWhereClause {
-                    suggestion: type_alias_generics.where_clause_span,
-                    sub,
-                },
+                BuiltinTypeAliasWhereClause { suggestion: generics.where_clause_span, sub },
             );
         }