compare typedef'ed sizes at compile time

// Example code which shows how to compare the two typedefs for size equivalency.

#define CONCAT_(a,b) a##b
#define CONCAT(a,b) CONCAT_(a, b)
#define STATIC_ASSERT(e) \
    ; enum { CONCAT(assert_line_, __LINE__) = 1/(int)(!!(e)) }

/* Note that ; is needed before enum if the STATIC_ASSERT is added right after case or label statement */
/* Note that multiple CONCATs are needed so that __LINE__ could be expanded .. Thus you can now have multiple STATIC_ASSERTs in the same code block */

typedef int uniqid_t;
typedef short mnid_t;

STATIC_ASSERT(sizeof(mnid_t) <= sizeof(uniqid_t));

int main(void)
{
    int t = 1;
    switch(t)
    {
        case 0:
            STATIC_ASSERT(sizeof(mnid_t) <= sizeof(int));
            break;
        default:
            break;
    }
    return 0;
}