How to avoid "null argument where non-null required" compiler warning

Question

Compiling the following code:

#include <string.h>
#define FOO (NULL)

int main(int argc, char *argv[])
{
    char *foo;

    if (FOO)
        foo = strdup(FOO);

    return 0;
}

results in the following compiler warning:

foo.c: In function ‘main’:
foo.c:9:3: warning: null argument where non-null required (argument 1) [-Wnonnull]
   foo = strdup(FOO);
   ^

However, strdup won't be called if FOO is NULL because of the if (FOO) check. Is there any way to avoid this warning?

Thanks!

Answer 1

If the idea is to assign a value to foo if FOO is defined, you could try:

//#define FOO "lorem ipsum"

int main()
{
    char *foo;
    #ifdef FOO
        foo = strdup(FOO);
    #endif
}

It also has an advantage that the entire if code is not included when not needed.