{"ast_node_type":"function","tokens":[{"end":80,"kind":"keyword","start":0,"text":"fn"}]}
    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
impl<'tcx> IntoDiagArg for GenericArg<'tcx> {
        self.to_string().into_diag_arg(&mut None)