syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"assert!(def.is_union());"}]}
source_snippet:                         assert!(def.is_union());
context_before:                     ty::Adt(def, ..) => {
context_after:                         self.tcx.dcx().create_err(UnionPattern { span: self.span })