namespace System.Collections.Immutable
{
    [CollectionBuilder(typeof(ImmutableArray), "Create")]
    [DefaultMember("Item")]
    public readonly struct ImmutableArray<T> : ICollection<T>, IEnumerable, IEnumerable<T>, IList<T>, IReadOnlyCollection<T>, IReadOnlyList<T>, ICollection, IList, IImmutableList<T>, IStructuralComparable, IStructuralEquatable, IEquatable<ImmutableArray<T>>
    {
        public static ImmutableArray<T> CastUp<TDerived>(ImmutableArray<TDerived!> items)
            where TDerived, class, T;
    }
}