> Ian Lance Taylor wrote: > ... > I don't personally see that as the question. This code is > undefined, and, therefore, is in some sense not C. If we take > any other attitude, then we will be defining and supporting > a different language. I think that relatively few people want > the language "C plus signed integers wrap", which is the language > we support with the -fwrapv option. > ...
No, all such code is perfectly legal C and specified to have undefined semantics in the instance of signed overflow; which seems clear from the excerpts noted by Gabriel <http://gcc.gnu.org/ml/gcc/2006-12/msg00763.html> may be specified by an implementation to assume whatever behavior desired. Thereby full liberty in given to the implementers of the compiler to apply whatever semantics are deemed most desirable; regardless of their practical utility, or historical compatibility. Ultimately the issue is to what degree should optimizations preserve semantics otherwise expressed and/or historically expected in their absents; and how should they when deemed desired be invoked (i.e. by named exception or default at -Ox).
