syntax_data: {"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let borrow = self.typeck_results.deref_pat_borrow_mode(ty, subpattern);
context_before:             hir::PatKind::Deref(subpattern) => {
context_after:                 PatKind::DerefPattern { subpattern: self.lower_pattern(subpattern), borrow }