syntax_data: {"ast_node_type":"other","tokens":[{"end":38,"kind":"keyword","start":0,"text":"debug!(?dfn,"}]}
source_snippet:         debug!(?dfn, "on_completion");
context_before:     fn on_completion(&self, dfn: usize) {
context_after:         self.map.borrow_mut().retain(|fresh_trait_pred, eval| {