struct A {
        int a[1];
        int b;
};

extern int c;

static int o[] = {
        [__builtin_offsetof(struct A, b)] = 0,          // OK
        [__builtin_offsetof(struct A, a[0])] = 0,       // OK
        [__builtin_offsetof(struct A, a[0*0])] = 0,     // OK
        [__builtin_offsetof(struct A, a[c])] = 0        // KO
};

/*
 * check-name: constexprness __builtin_offsetof()
 *
 * check-error-start
constexpr-offsetof.c:12:39: error: bad constant expression
 * check-error-end
 */