It's not about types or consts, but the lack of regions

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -170,7 +170,7 @@ pub fn type_known_to_meet_bound_modulo_regions<'a, 'tcx>(
         result
     );
 
-    if result && ty.has_infer_types_or_consts() {
+    if result && ty.has_non_region_infer() {
         // Because of inference "guessing", selection can sometimes claim
         // to succeed while the success requires a guess. To ensure
         // this function's result remains infallible, we must confirm