syntax_data: {"ast_node_type":"other","tokens":[{"end":57,"kind":"keyword","start":0,"text":"self.provisional_cache.retain(|&input,"}]}
source_snippet:         self.provisional_cache.retain(|&input, entries| {
context_before:         #[allow(rustc::potential_query_instability)]
context_after:             entries.retain_mut(|entry| {