syntax_data: {"ast_node_type":"other","tokens":[{"end":35,"kind":"keyword","start":0,"text":"scrut:"}]}
source_snippet:         scrut: Option<&Expr<'tcx>>,
context_before:         refutability: RefutableFlag,
context_after:     ) -> Result<(PatCtxt<'p, 'tcx>, UsefulnessReport<'p, 'tcx>), ErrorGuaranteed> {