Function splice_match_arg_entry 

fn splice_match_arg_entry(content: &str, entry: &MatchArgChoicesEntry) -> String

content with one match_arg parameter’s placeholders resolved from its MatchArgChoicesEntry: every choices placeholder (the formal and the check) by match_arg_formal, and the check’s , <aliases placeholder> by match_arg_aliases_arg, which is empty for a type without aliases.