Check associated type where-clauses for lifetimes

Author: reddevilmidzy

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -119,6 +119,14 @@ impl<'a> PostExpansionVisitor<'a> {
         ImplTraitVisitor { vis: self, in_associated_ty }.visit_ty(ty);
     }
 
+    fn check_ty_alias_after_where_clause(&self, clause: &ast::WhereClause) {
+        for predicate in &clause.predicates {
+            if let ast::WherePredicateKind::BoundPredicate(bound_pred) = &predicate.kind {
+                self.check_late_bound_lifetime_defs(&bound_pred.bound_generic_params);
+            }
+        }
+    }
+
     fn check_late_bound_lifetime_defs(&self, params: &[ast::GenericParam]) {
         // Check only lifetime parameters are present and that the
         // generic parameters that are present have no bounds.
@@ -410,7 +418,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     fn visit_assoc_item(&mut self, i: &'a ast::AssocItem, ctxt: AssocCtxt) {
         let is_fn = match &i.kind {
             ast::AssocItemKind::Fn(_) => true,
-            ast::AssocItemKind::Type(box ast::TyAlias { ty, .. }) => {
+            ast::AssocItemKind::Type(box ast::TyAlias { ty, after_where_clause, .. }) => {
+                self.check_ty_alias_after_where_clause(after_where_clause);
                 if let (Some(_), AssocCtxt::Trait) = (ty, ctxt) {
                     gate!(
                         &self,

tests/ui/associated-types/associated-type-where-non-lifetime-const.rs

@@ -0,0 +1,13 @@
+//! regression test for #148627
+
+#![feature(associated_type_defaults)]
+
+trait Trait {
+    type Assoc2
+        = ()
+    where
+        for<const C: usize> [(); C]: Copy;
+    //~^ ERROR: only lifetime parameters can be used in this context
+}
+
+fn main() {}

tests/ui/associated-types/associated-type-where-non-lifetime-const.stderr

@@ -0,0 +1,13 @@
+error[E0658]: only lifetime parameters can be used in this context
+  --> $DIR/associated-type-where-non-lifetime-const.rs:9:19
+   |
+LL |         for<const C: usize> [(); C]: Copy;
+   |                   ^
+   |
+   = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
+   = help: add `#![feature(non_lifetime_binders)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.

tests/ui/associated-types/associated-type-where-non-lifetime-type.rs

@@ -0,0 +1,18 @@
+//! regression test for #149233
+
+trait Foo {
+    type Bar<'a>
+    where
+        Self: Sized;
+    fn test(&self);
+}
+impl Foo for () {
+    type Bar<'a>
+        = ()
+    where
+        for<T> T:;
+    //~^ ERROR: only lifetime parameters can be used in this context
+    fn test(&self) {}
+}
+
+fn main() {}

tests/ui/associated-types/associated-type-where-non-lifetime-type.stderr

@@ -0,0 +1,13 @@
+error[E0658]: only lifetime parameters can be used in this context
+  --> $DIR/associated-type-where-non-lifetime-type.rs:13:13
+   |
+LL |         for<T> T:;
+   |             ^
+   |
+   = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
+   = help: add `#![feature(non_lifetime_binders)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.