{"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"diag.arg(\"expr\","}]}
        diag.arg("expr", self.expr.as_deref().unwrap_or("NONE"));
    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {