syntax_data: {"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"early_dcx.early_fatal(\"using"}]}
source_snippet:             early_dcx.early_fatal("using `--json` requires also using `--error-format=json`");
context_before:         _ if !matches.opt_strs("json").is_empty() => {
context_after:         }