syntax_data: {"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"err.arg(\"bad_modifiers\","}]}
source_snippet:             err.arg("bad_modifiers", self.info.bad_modifiers);
context_before:             }
context_after:             err.arg("bad_ref_pats", self.info.bad_ref_pats);