syntax_data: {"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let ty::Closure(_, args) = *self_ty.kind() else {
context_before:     ) -> ty::PolyTraitRef<'tcx> {
context_after:             bug!("expected closure, found {self_ty}");