[Bug sanitizer/88479] sanitizer should provide an option to detect conversion to signed integer that overflows

["joseph at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88479

--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Thu, 13 Dec 2018, vincent-gcc at vinc17 dot net wrote:

> The C standard would have to drop ones' complement and sign-magnitude first.

And there's substantial support for doing so.

> In any case, this is not a good programming practice, and for some projects, it

If you want to do modulo arithmetic on signed values, the idiom (in 
common-usage C which supports conversions to signed integer types as being 
modulo) is to convert to unsigned, do arithmetic on unsigned and convert 
back to signed.  I don't think that's a bad practice.  (Unintentional 
overflows on conversion to signed would be bad, but the problem is 
determining what's intentional.)