Is this an useful optimization ??

I was thinking mostly of integers, not pointers. However I am hard pressed to think of an
example where a pointer overflow would not safely wrap around _in practice_. Even with x86 FAR
pointers, the offset will safely wrap around. There will be no trap and the comparison will
still work.

Are there many architectures, in use today, where pointers are not integers and do not wrap
around on overflow ? Secondly, do these architecture run Linux and are they supported by GCC ?

Regardless of the answer to these questions, why would people writing  code with zero chance
for running on those architectures, be maniacs ?

The C Standard is not a measurement for good programming. It simply has a set of restrictions
to ensure portability between all kinds of weird architectures (I should say it fails in this
miserably, but that is beside the point). However portability is not the only, and by far not
the most important measurement of code.