reuse of macro formal 'identifier'
The formal parameter list of a macro definition uses the identifier more than once. Identifiers in the macro's parameter list must be unique. The following sample generates C2009:
#define macro1(a,a) (a*a) // C2009 // try .. // #define macro2(a) (a*a) // #define macro3(a,b) (a*a) void main() { }