The func module makes sure that you can use the predefined
identifier __func__ as defined by C99 in your code.
A small example is:
#include <config.h>
#include <stdio.h> /* for printf */
int main (void)
{
printf ("%s: hello world\n", __func__);
}
Note that sizeof cannot be applied to __func__: On SunPRO C
compiler, sizeof __func__ evaluates to 0.