{"ast_node_type":"variable","tokens":[{"end":89,"kind":"keyword","start":0,"text":"let"}]}
        let msg = dcx.eagerly_translate_for_subdiag(&diag, msg); // after the `arg` calls
        diag.arg("note", self.note);
        diag.sub(Note, msg, diag.span.primary_span().unwrap_or(DUMMY_SP).into());