> They need not wrap around. People that are actually on the C standards
> committee have told you this multiple times.
Yes, and may clearly produce erroneous results if the value ranges
are not consistent with the factual behavior of an implementation, i.e.:
int x;
volatile int v;
x = (v ? 0 : INT_MAX) + 1; // [1, INT_MAX] (without -fwrapv)
if (x <= 0) // Which may be erroneously
printf("%i is <= 0.", x); // optimized away, with this.
else
printf("%i is > 0.", x); // Leaving only this in error.
As regardless of the value of x produced by an implementation, it's wrong
to presume a result which is not consistent with the factual behavior of
that implementation. Therefore -fwrapv must be presumed for all targets
which effectively wrap signed integer overflows, as otherwise non-
conformant behaviors may result. (i.e. effectively all present targets)
As I doubt "-2147483648 > 0" or "0 > 0" (as may otherwise result from
typical 2's or 1's complement implementations which silently wrap
overflows), can be justified as being a valid conforming result in any
circumstance. (and confess that I have nothing more to add if not obvious).
