syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"metrics_dir:"}]}
source_snippet:     metrics_dir: Option<PathBuf> = (None, parse_opt_pathbuf, [UNTRACKED],
context_before:         "gather metadata statistics (default: no)"),
context_after:         "the directory metrics emitted by rustc are dumped into (implicitly enables default set of metrics)"),