syntax_data: {"ast_node_type":"variable","tokens":[{"end":99,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let existential_trait_ref = ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref);
context_before:             VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {