Hello Axel,
i played around with the suggested option -Wno-div-by-zero, but g++ does not warn about the divsion by zero. I tested the following:
foo(4./0) // float/integer
foo(4/0) // integer/integer
foo(4/0.) // integer/float
foo(4./0.) // float/float
g++ does not warn about this cases. Here the extended testcase:
#include <iostream>
template <typename T1, typename T2> inline T1 foo (T1 const& a, T2 const& b)
{
// ....
return a/b;
}
int main()
{
std::cout << foo(4.,0) << std::endl;
std::cout << foo(4,0.) << std::endl;
std::cout << foo(4,0) << std::endl;
std::cout << foo(4.,0.) << std::endl;
return 0;
}
Best regards
Martin
Hello Martin,
the reason is given in the manual:
-Wno-div-by-zero
Do not warn about compile-time integer division by zero.
Floating point division by zero is not warned about, as
it can be a legitimate way of obtaining infinities and NaNs.
So you should obtain a warning with "foo(4,0)", but not with "foo(4.,0)"
Axel
-------- Original-Nachricht --------
> Datum: Sun, 21 Jun 2009 08:34:50 -0400
> Von: John Fine <johnsfine@xxxxxxxxxxx>
> An: Martin Ettl <ettl.martin@xxxxxx>
> CC: gcc-help@xxxxxxxxxxx
> Betreff: Re: why does g++ not warn about division by zero?
> Have you tried that at various optimization levels?
>
> At lower optimization levels, the "inline" keyword should not cause the
> function to actually get inlined.
>
> If the function is not actually inlined, gcc cannot be aware of the
> divide by zero.
>
> I don't happen to know whether gcc would warn if it were aware of the
> divide by zero, nor if actually inlining is sufficient to make it
> aware. I'm just saying actually inlining should be necessary to make it
> aware of the divide by zero.
>
> Martin Ettl wrote:
> > template <typename T1, typename T2> inline T1 foo (T1 const& a, T2
> const& b)
> > {
> > // ....
> > return a/b;
> > }
> >
> > int main()
> > {
> > std::cout << foo(4.,0) << std::endl;
> > return 0;
> > }
> >
> > I compiled the testprogramm with following command:
> > g++ -W -Wall -pedantic -o test test.cpp
> >
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