{"ast_node_type":"function","tokens":[{"end":77,"kind":"keyword","start":0,"text":"fn"}]}
    fn file_index_to_file(&self, index: SourceFileIndex) -> Arc<SourceFile> {
    #[inline]
        let CacheDecoder { tcx, file_index_to_file, file_index_to_stable_id, .. } = *self;