Overloading Macro on Number of Arguments

Question

I have two macros FOO2 and FOO3:

#define FOO2(x,y) ...
#define FOO3(x,y,z) ...

I want to define a new macro

Answer 1

This seems to work fine on GCC, Clang and MSVC. It's a cleaned up version of some of the answers here

#define _my_BUGFX(x) x

#define _my_NARG2(...) _my_BUGFX(_my_NARG1(__VA_ARGS__,_my_RSEQN()))
#define _my_NARG1(...) _my_BUGFX(_my_ARGSN(__VA_ARGS__))
#define _my_ARGSN(_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,N,...) N
#define _my_RSEQN() 10,9,8,7,6,5,4,3,2,1,0

#define _my_FUNC2(name,n) name ## n
#define _my_FUNC1(name,n) _my_FUNC2(name,n)
#define GET_MACRO(func,...) _my_FUNC1(func,_my_BUGFX(_my_NARG2(__VA_ARGS__))) (__VA_ARGS__)

#define FOO(...) GET_MACRO(FOO,__VA_ARGS__)