Adjust tests

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

@@ -1243,7 +1243,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 self.infcx.tcx.trait_is_coinductive(data.def_id())
             }
             ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => {
-                // TODO: GCE is going away
+                // FIXME(generic_const_exprs): GCE needs well-formedness predicates to be
+                // coinductive, but GCE is on the way out anyways, so this should eventually
+                // be replaced with `false`.
                 self.infcx.tcx.features().generic_const_exprs()
             }
             _ => false,