{"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"//"}]}
            // Parsing a pattern of the form `fieldname: pat`.
        let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
            let fieldname = self.parse_field_name()?;