[PATCH][4.3] Deprecate -ftrapv

[Robert Dewar]

Richard Kenner wrote:
>> No one needs a broken anything, 
> 
> Not necessarily and perhaps not in this case.  Let's suppose there was
> an implementation of -ftrapv that did trap, but only about 80% of the
> time.  Such an implementation would nevertheless be useful in C since
> there overflow is not a required feature of the language, but merely
> useful, and you could well argue that it's better to catch 80% of the
> overflows than 0%. But for Ada, it's a language requirement that we
> catch *all* overflows, so an implementation that was 80% correct there
> isn't useful at all since an alternate one is required.

Might still be useful as the default behavior if it was significantly
more efficient than the complete mechanism, and if in practice the
intent was to catch the other 20% over time.