Note that in my example, what I meant by "when you pass a derived where
base is expected" was using templates while optionally using c++20 concepts
to make sure the enum is from a Hirearchy. Basically this:
Template< typename Enum_t>
Enum_t func(){
return Enum_t::red;
}
Again, you can't use assign a derived enumerators to a base one directly
but the wrapper class can provide user-defined assignment operators and
constructors that do that for you. This is by design so that you don't mix
enums together


On Mon, 20 Apr 2026, 4:00 pm Muneem, <itfllow123_at_[hidden]> wrote:

> You do have a point that inheritance with enum classes would be great for
> group enums together, but can't we do it already? Like:
> enum class base_enum{red, Violet, blue};
> Struct base{
> using Type= base_enum;
> };
> enum class derived_enum{red, Violet, blue};
> Struct derived:base{
> using Type= base_enum;
> };
> This would allow you to pass derived where base is expected and use the
> Type of derived. Inheriting enumerators on the other hand would not be a
> good idea since you are mixing enums instead of group them.
>
>
> On Mon, 20 Apr 2026, 3:47 pm Andrey Fokin via Std-Proposals, <
> std-proposals_at_[hidden]> wrote:
>
>> Title: Pxxxx: Add inheritance for Enum Class enumerations
>> Author: Andrey Fokin, lazzyfox_at_[hidden]
>> Date: 2026-04-20
>> Project: Programming Language C++, Library Working Group
>> Abstract: New inheritance feature to enum class (scoped enumerations)
>> 1. Introduction
>> According my experience the are situations when scped enumerations could
>> be presented in OOP style – base enumeration type and some ancestors of.
>> For example – we have to define a list of colors for traffic lights device.
>> Is simple case we have just three colors and our enum could looks like
>> enum class TrafficLight:uint8_t { Red, Yellow, Green };
>> And probably this enum will cover biggest part of cases. But if we need
>> to have a case wit Trafficligt wit left, rgih or two arrows we need ot use
>> three diffeerent data types for each with big part of duplicated data in
>> eatch.
>> Case 1- additional letf arrow enum class TrafficLight_LefatArrow:uint8_t
>> { Red, Yellow, Green, LeftArrow };
>> Case 2- additional right arrow enum class TrafficLight_RightArrow:uint8_t
>> { Red, Yellow, Green, RightArrow };
>> Case 3- two additional arrows enum class TrafficLight_TwoArrows:uint8_t {
>> Red, Yellow, Green, LeftArrow, RightArrow };
>>
>> In case of inheritance could be possible use as first case as a base
>> class and athers as inherited to exclude overlapping data duplication and
>> casese above cold looks like
>> Case 4- additional letf arrow enum class TrafficLight:LefatArrow:uint8_t
>> {LeftArrow };
>> Case 5- additional right arrow enum class TrafficLight:RightArrow:uint8_t
>> {RightArrow };
>> Case 6- two additional arrows enum class TrafficLight_TwoArrows:uint8_t
>> {LeftArrow, RightArrow };
>>
>> 2. Motivation and scope
>> Proposal could make more cleare code structure and decrease code
>> overlapping and had writing
>> 3. Design decisions
>> It could be compiler extension
>>
>>
>>
>>
>> BRG,
>> Andrey
>> --
>> Std-Proposals mailing list
>> Std-Proposals_at_[hidden]
>> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>>
>