From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2025-06-15 11:22:47
On 12 Jun 2025 18:56, Peter Dimov via Boost wrote:
> Andrey Semashev wrote:
>> 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.
>
> Not quite. For scoped enums, and those with fixed underlying type, all values
> of the underlying type is allowed. For "normal" enums, it's a bit more complex;
> the minimum number of bits that can represent all enumerators is computed,
> and values that fit into this number of bits are allowed.
>
> So any bitwise combination of enumerators is allowed, but negation may not be.
Yes, thank you for the correction.