Presently, enums support these properties:

.init = lexically-first member value
.min = smallest value
.max = largest value
.sizeof = size of underlying storage type

I propose adding another property, .length

The value would be the array-declaration-friendly number of elements in the enum. Thus, 

enum E { A, B, C };

int[ E.length ] counters; // int[3]
 
There is always the possibility that enum values would be declared as duplicates of each other:

enum F { A = 0, B, C = 0 };

In that case, .length would _still_ return 3, because it's defined at the number, not the number(unique) or anything. (And because not all enumerated types will supported ==).