CWG2932 Value range of empty enumeration

[jensmaurer]

C++17 defined the values of an empty enumeration to be just 0.

As-is, CWG2932 restores that rule.

However, popular implementations determine the value range of an empty enumeration to be 0 and 1, reflecting the single bit of storage assigned to the representation.

EWG should decide whether to keep the C++17 rule or adjust the wording to the implementation practice.

[erichkeane]

EWG discussed this during the Monday AM session in Sofia. After extensive discussion, we determined that we require a paper to properly consider the state of the current implementations, the differences in the various standards versions, and the options presented. @GabrielDosReis volunteered to be 'person in charge' for that paper.