Function rustc_middle::ty::util::fold_list

pub fn fold_list<'tcx, F, T>(
    list: &'tcx List<T>, 
    folder: &mut F, 
    intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx List<T>
) -> &'tcx List<T> where
    F: TypeFolder<'tcx>,
    T: TypeFoldable<'tcx> + PartialEq + Copy,