Do not warn about an ununsed function, if it is marked with __attribute__((used)).
[cparser] / parsetest / constexpr.c
1 int k;
2
3 enum ENUM {
4         bla = 2 < 4 ? 0 : k
5 };
6
7 int main(void)
8 {
9         return bla;
10 }