On: Signed Integers Are Two’s Complement

[rom1v]

size_t is unsigned, overflow is defined.

[JdeBP → rom1v]

The type of index is, however, signed int.

[rom1v → JdeBP]

You're right, I read diagonally :)

However, the optimization argument for signed overflow seems weird to me, because I can't see any reason why this argument would not apply to unsigned overflow as well.

If we keep undefined behavior to optimize things like "if (n < n + 1)" when n is signed, why not do the same when n is unsigned?

Conversely, if there is a good reason not to, then why would it not apply to signed overflow as well?