------- Comment #13 from rguenth at gcc dot gnu dot org 2007-02-23 09:22
-------
In reply to comment #8
To understand the issues a little bit more -- are there any requirements on
overflow behavior of the _base_ type? Suppose a type T with range -100..120
has indeed be assigned a signed char with precision 8 (and so range -128..127).
If we now do arithmetic like (to add two Ts)
T foo(T t1, T t2)
{
signed char t1_base = (signed char)t1;
signed char t2_base = (signed char)t2;
signed char res_base = t1_base + t2_base;
if (res_base < 10 || res_base > 120)
abort ();
return (T)res_base;
}
is it ok to not raise a constraint error if I happen to add 100 and 100 which
wraps on the machine in signed char precision back to a valid value inside
the range of T?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30911
