Generics for multiparameter C functions in C11

Question

I understand C11 generics for one-parameter functions, like this: (from here)

#define acos(X) _Generic((X), \     long double complex: cacosl, \     double complex: cacos, \     float complex: cacosf, \     long double: acosl, \     float: acosf, \     default: acos \     )(X) 

But, it seems to be a pain for functions with two arguments, you need to nest calls to _Generic, which is really ugly; Excerpt from the same blog:

#define pow(x, y) _Generic((x), \ long double complex: cpowl, \  double complex: _Generic((y), \ long double complex: cpowl, \ default: cpow), \  float complex: _Generic((y), \ long double complex: cpowl, \ double complex: cpow, \ default: cpowf), \  long double: _Generic((y), \ long double complex: cpowl, \ double complex: cpow, \ float complex: cpowf, \ default: powl), \  default: _Generic((y), \ long double complex: cpowl, \ double complex: cpow, \ float complex: cpowf, \ long double: powl, \ default: pow), \  float: _Generic((y), \ long double complex: cpowl, \ double complex: cpow, \ float complex: cpowf, \ long double: powl, \ float: powf, \ default: pow) \ )(x, y) 

Is there a way to have more human being-readable generics for multiparameter functions, like this for instance :

#define plop(a,b) _Generic((a,b), \       (int,long): plopii, \       (double,short int): plopdd)(a,b) 

Thanks in advance for your replies. The basic idea would be having a macro wrapper for _Generic.

Answer 1

Given that the controlling expression of _Generic is not evaluated, I'd suggested applying some arithmetic operation that does the appropriate type-combining, and switching on the result. Thus:

#define OP(x, y) _Generic((x) + (y), \     long double complex: LDC_OP(x, y), \     double complex: DC_OP(x, y), \     ... ) 

Of course this only works for certain cases, but you can always expand out those for which the "collapsed" type is not helpful. (This would let one take care of array-N-of-char vs char *, for instance, as with the linked printnl example, and then if the combined type is int, one can go back and check for char and short.)