On Thu, Jun 12, 2025 at 1:37 PM Andrey Semashev via Boost < boost@lists.boost.org> wrote:
I am mostly talking about conceptual meaning of enum: set<int> is not int.
The standard defines enumerations as "a distinct type with named constants". That is, its a way to define a number of named constants and associate them with a type. The standard then goes on to say that an enumeration has an underlying type. It doesn't say that the set of values of the enum type is limited to the named constants (as it says e.g. for bool); other values, as long as those values are representable by the underlying type, are implicitly allowed. So when you're saying an enum cannot have values other than the named constants (I'm assuming that's what you mean by "set<int>" above), you are talking about one particular usage scenario of the enum, where you simply don't use values other than the named constants. That's not the only valid usage scenario, and enums implementing bit masks are not a misuse of enums.
Yeah when I sent an email I realized I should have been more precise. I
know what current state of language is, I just think it is bad, and I try to avoid confusing/bad parts of C++. Again according to me, I am not trying to convert you, I understand this is personal preference. Sankel proposal I linked explains in detail what I am talking about: In C++ enum is a "union" of different things(not to be confused with union as language construct). I dislike that since it makes reasoning harder, i.e. it would be better if that functionality was split. So in my ideal world flag is a language feature and enum is a language feature, so | is not allowed on enum values. Sankel proposal wanted to add [[exhaustive]] that beside ugly syntax is something I would like to see in the language.