syntax_data: {"ast_node_type":"other","tokens":[{"end":27,"kind":"keyword","start":0,"text":"pat:"}]}
source_snippet:         pat: &'p Pat<'tcx>,
context_before:         cx: &PatCtxt<'p, 'tcx>,
context_after:     ) -> Result<&'p DeconstructedPat<'p, 'tcx>, ErrorGuaranteed> {