{"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"if"}]}
            if a_is_expected {
        self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
                Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::Yes, a, b))