In case the arguments can be literally any pp-tokens then it turns complex. Otherwise, in case the arguments are either for example int or implicitly convertible to int, it's as trivial as sizeof (int[]){__VA_ARGS__) / sizeof(int). However, pointers being implicitly convertible to int is a non-standard compiler extension which turns the program non-conforming.

I think the most useful case would be when each argument is an expression. Arbitrary pp-tokens are too complex, I agree. And integer is too restrictive (but useful already; lacking anything better). Thanks!

BTW, in C2y, your solution can be simplified as countof (int[]){__VA_ARGS__}.