syntax_data: {"ast_node_type":"other","tokens":[{"end":60,"kind":"keyword","start":0,"text":"err.arg(\"bad_ref_pats\","}]}
source_snippet:             err.arg("bad_ref_pats", self.info.bad_ref_pats);
context_before:             err.arg("bad_modifiers", self.info.bad_modifiers);
context_after:             err.arg("is_hard_error", true);