syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"cache:"}]}
source_snippet:     cache: &'o ProvisionalEvaluationCache<'tcx>,
context_before: struct TraitObligationStackList<'o, 'tcx> {
context_after:     head: Option<&'o TraitObligationStack<'o, 'tcx>>,