{"ast_node_type":"other","tokens":[{"end":83,"kind":"keyword","start":0,"text":"//"}]}
        // If origin_expr exists, then expected represents the type of origin_expr.
    fn pattern_cause(&self, ti: &TopInfo<'tcx>, cause_span: Span) -> ObligationCause<'tcx> {
        // If span also exists, then span == origin_expr.span (although it doesn't need to exist).