The solution of Gregory Pakosz worked great. But I had two minor problems with it:
Compiling with the pedantic option I got the warning: "ISO99 requires rest arguments to be used".
This is caused by the variad arguments in the first FOR_EACH_1 macro. Removing those and changing the call to FOR_EACH_1 in FOR_EACH_2 removed this warning.
#define FOR_EACH_1(what, x)
#define FOR_EACH_2(what, x, ...)\
what(x); \
FOR_EACH_1(what);
Since i used it in a very generic way, i sometimes had to call the repeat macro with only 1 argument. (I know it does not make sense to repeat an item 1 times ;)). Fortunately the solution to this problem was quite simple. Just removing the x parameter from the FOR_EACH macro.
#define FOR_EACH(what, ...) FOR_EACH_(FOR_EACH_NARG(__VA_ARGS__), what, __VA_ARGS__)
Here the complete listing with the two changes:
#define CONCATENATE(arg1, arg2) CONCATENATE1(arg1, arg2)
#define CONCATENATE1(arg1, arg2) CONCATENATE2(arg1, arg2)
#define CONCATENATE2(arg1, arg2) arg1##arg2
#define FOR_EACH_1(what, x) \
what(x)
#define FOR_EACH_2(what, x, ...) \
what(x); \
FOR_EACH_1(what, __VA_ARGS__);
#define FOR_EACH_3(what, x, ...) \
what(x); \
FOR_EACH_2(what, __VA_ARGS__);
#define FOR_EACH_4(what, x, ...) \
what(x); \
FOR_EACH_3(what, __VA_ARGS__);
#define FOR_EACH_5(what, x, ...) \
what(x); \
FOR_EACH_4(what, __VA_ARGS__);
#define FOR_EACH_6(what, x, ...) \
what(x); \
FOR_EACH_5(what, __VA_ARGS__);
#define FOR_EACH_7(what, x, ...) \
what(x); \
FOR_EACH_6(what, __VA_ARGS__);
#define FOR_EACH_8(what, x, ...) \
what(x); \
FOR_EACH_7(what, __VA_ARGS__);
#define FOR_EACH_NARG(...) FOR_EACH_NARG_(__VA_ARGS__, FOR_EACH_RSEQ_N())
#define FOR_EACH_NARG_(...) FOR_EACH_ARG_N(__VA_ARGS__)
#define FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
#define FOR_EACH_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0
#define FOR_EACH_(N, what, x, ...) CONCATENATE(FOR_EACH_, N)(what, x, __VA_ARGS__)
#define FOR_EACH(what, ...) FOR_EACH_(FOR_EACH_NARG(__VA_ARGS__), what, __VA_ARGS__)
