syntax_data: {"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let predicate = trait_ref.upcast(tcx);
context_before:     let mut visited = PredicateSet::new(tcx);
context_after:     let mut stack: SmallVec<[(ty::TraitRef<'tcx>, _, _); 5]> =