syntax_data: {"ast_node_type":"other","tokens":[{"end":43,"kind":"keyword","start":0,"text":"err.arg(\"is_hard_error\","}]}
source_snippet:             err.arg("is_hard_error", true);
context_before:             err.arg("bad_ref_pats", self.info.bad_ref_pats);
context_after:             err.subdiagnostic(sugg);