New clang compiler complains tautology in this code

[liuliu]

https://github.com/pixelglow/ZipZap/blob/master/ZipZap/ZZArchive.mm#L149

This line pointing to a static int sign: https://github.com/pixelglow/ZipZap/blob/master/ZipZap/ZZHeaders.h#L151

Should this be signature?

[combinatorial]

I agree, it should be.