Function parse_discard 

pub fn parse_discard(job: ParseJob<'_, '_>) -> Result<(), ParseError>

No-tree parse: drive the same lexer/postlex/feed loop as parse_with but under [Reduce::Discard], so every reduce yields NodeValue::None with no shaping and no arena write. Returns Ok(()) on accept, the same ParseError on reject. Because the reduce value never steers feed_token, this consumes the byte-identical token stream and reaches the identical accept/reject as the tree path — only tree construction is elided. The peer to the POC’s parse_no_arena for no-tree benches (and a discard-parse API candidate: recognition-only validation without paying for a tree).