syntax_data: {"ast_node_type":"other","tokens":[{"end":84,"kind":"keyword","start":0,"text":"std::mem::replace(&mut"}]}
source_snippet:                             std::mem::replace(&mut self.in_union_destructure, true);
context_before:                         let old_in_union_destructure =
context_after:                         visit::walk_pat(self, pat);