syntax_data: {"ast_node_type":"other","tokens":[{"end":56,"kind":"keyword","start":0,"text":"#[allow(rustc::potential_query_instability)]"}]}
source_snippet:             #[allow(rustc::potential_query_instability)]
context_before:             // Same as above, but for expansions instead of syntax contexts.
context_after:             let latest_expns = { mem::take(&mut *self.latest_expns.lock()) }.into_iter();