Treating the abusive unsigned syndrome

[Michel Fortin]

On 2008-11-25 10:59:01 -0500, Andrei Alexandrescu 
<SeeWebsiteForEmail at erdani.org> said:

> (3) u - u

Just a note here, because it seems to me you're confusing two issues 
with that "u - u" thing. The problem with "u - u" isn't one of unsigned 
vs. signed integers at all. It's a problem of possibly going out of 
range, a problem that can happen with any type but is more likely with 
unsigned integers since they're often near zero.

If you want to attack that problem, I think it should be done in a 
coherent manner with other out-of-range issues. Going below uint.min 
for an uint or below int.min for an int should be handled the same way. 
Personally, I'd just add a compiler switch for runtime range checking 
(just as for array bound checking).

Treating the result u - u as __intuint is dangerous: uint.max - 1U 
gives you a value which int cannot hold, but you'd allow it to convert 
implicitly and without warning to int? I don't like it.

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/