Add Clause::ConstArgHasType variant

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -993,6 +993,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     bug!("AliasEq is only used for new solver")
                 }
                 ty::PredicateKind::Ambiguous => Ok(EvaluatedToAmbig),
+                ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..)) => {
+                    unimplemented!()
+                }
             }
         })
     }