------- Comment #130 from nszabolcs at gmail dot com 2009-07-22 12:10 -------
(In reply to comment #129)
> I am a bit wondering if this bug is also for the case (a < b) && (b < a) ==
> true. Is it?
i guess so, see:
#include <stdlib.h>
#include <stdio.h>
#define axiom_order(a,b) !(a < b && b < a)
#define axiom_eq(a) a == a
#define third ((double)atoi("1")/atoi("3"))
int main(void) {
if (axiom_order(third, third))
puts("ok");
else
puts("error");
if (axiom_eq(third))
puts("ok");
else
puts("error");
return 0;
}
here this prints
error
error
with gcc 4.2 and -S shows that this is long double vs double precision problem
> Because if so, this becomes way more serious, as for example std::set<double>
> is broken then (and depending on the STL implementation, it will throw
> assertions then).
in C99 (+TC1,TC2,TC3) different precision is not allowed
5.1.2.3 p12:
... In particular, casts and assignments are required to perform their
specified conversion
5.2.4.2.2 p8:
Except for assignment and cast (which remove all extra range and precision),
the values 8 of operations with floating operands and values subject to the
usual arithmetic conversions and of floating constants are evaluated to a
format whose range and precision may be greater than required by the type.
i'm not sure about c++ though
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323
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