{"ast_node_type":"function","tokens":[{"end":83,"kind":"keyword","start":0,"text":"fn"}]}
    fn parse_field_ident(&mut self, adt_ty: &str, lo: Span) -> PResult<'a, Ident> {
    /// for better diagnostics and suggestions.
        let (ident, is_raw) = self.ident_or_err(true)?;