avoid null-pointer-subtraction error

[nitzmahone]

Newer compilers generate warnings/errors about null pointer subtractions being an undefined behavior. Use matching non-zero offsets (as suggested by arigo) to avoid the error.

[nekopsykose]

is there any reason to not make this offsetof(%s, %s) instead?

[arigo]

We can't in this case, because we have the name of the pointer type, and not the struct name type. See the next line after the else: for the case where we have the struct name and can just emit offsetof.

[nekopsykose]

that makes sense, thanks :)