[peterfirefly]

    #define DEF   (ABC+(GHI<<JKL_SHIFT))

[Kranar]

Please make a point.

[peterfirefly]

I did. This is exactly what we need for constexpr for.

[Kranar]

Nothing you've demonstrated requires the use of constexpr. A const is perfectly suited for that.

[peterfirefly]

One of us doesn't know C.

[Kranar]

https://godbolt.org/z/de1YGG5r1

I hope for your sake that you don't speak this way other than anonymously on the Internet; it reflects very poorly of you.