guess i’d vote for having it do the obvious thing - flip all the bits including sign.
~(-256) = 255
~(-2) = 1
~(-1) = 0
2’s-complement is standard enough that breaking it would violate principle of least surprise…
let’s see, the alternative:
would mean, in int16, that ~(-1) = -1 * (~1) = -1 * 0xfffe = … 2? i feel weird.