Using __VA_ARGS__ in a nested macro, but the args are truncated

Question

I'm doing something like below:

#define AA(mac, a, ...) mac(a, __VA_ARGS__)
#define MAC1(a, b, c) a##b##c

AA(MAC1, 0, 1, 2)

what I really want is to translate "AA(MAC1, 0, 1, 2)" to "012", but I get "01,2", which is reasonalbe though, but not I want.

Edit: A work around is to remove the VA_ARGS, and define a AA like

#define AA(mac,a,b,c,d,e,f,g,h,...) mac(a,b,c,d,e,f,g,h)

#define MAC1(a, b, c) a##b##c

AA(MAC1, 0, 1, 2)

gives what I what, "012", I don't know why though.

Answer 1

Your initial code:

#define AA(mac, a, ...) mac(a, __VA_ARGS__)
#define MAC1(a, b, c) a##b##c

AA(MAC1, 0, 1, 2)

seems to work fine:

$ gcc -E a.c > a.pp ; cat a.pp
# 1 "a.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 31 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 32 "<command-line>" 2
# 1 "a.c"



012

So, maybe there's an issue with your compiler or IDE.