[v3] Use Solaris prototypes if possible (PR libstdc++-v3/1773)
Paolo Carlini
paolo.carlini@oracle.com
Thu Aug 18 12:31:00 GMT 2011
Hi,
> On Tue, 9 Aug 2011, Rainer Orth wrote:
>
>> This patch is the last but one in the series to finally fix
>>
>> PR libstdc++-v3/1773 __cplusplus defined to 1, should be 199711L
>
> Only piece left before the switch :-)
>
>> * include/c_global/cmath (double abs(double)): Wrap in
>> !__CORRECT_ISO_CPP_MATH_H_PROTO1 &&
>> !__CORRECT_ISO_CPP_MATH_H_PROTO2.
>> (float abs(float), long double abs(long double): Wrap in
>> !__CORRECT_ISO_CPP_MATH_H_PROTO1.
>> (float acos(float), long double acos(long double)): Likewise.
> [...]
>
> I guess it would also be possible to reorder the declarations so as to
> have a single #ifdef (well, two), but then the various overloads of
> each function wouldn't be adjacent anymore.
Indeed. I would say let's not re-order for now, I'll have a further look
later on.
>> * include/tr1/cmath (float fabs(float), long double fabs(long
>> double)): Wrap in !__CORRECT_ISO_CPP_MATH_H_PROTO1.
>
> There is a comment:
> // Note: we deal with fabs in a special way, because an using std::fabs
> // would bring in also the overloads for complex types, which in C++0x
> // mode have a different return type.
>
> and then it proceeds to using ::fabs and declare the float and long
> double overloads. Now on solaris, using ::fabs is going to be
> equivalent to using std::fabs. I don't know if that creates problems
> for the complex types, and in that case what can be done about it
> (declare fabs(double) instead of importing the global one?).
We have a testcase for that issue, see Rev 170083,
testsuite/tr1/headers/c++200x/complex.cc. I think defining fabs(double)
in namespace tr1 is not an option, because an actual definition vs an
using leads to errors when the user does an using std::tr1 in the global
namespace (a recurring issue, this one, we must be very careful). I
think for now we have to live with a possible regression of the above
testcase on Solaris, seems a relatively minor issue to me, nobody
noticed the problem for *years*.
Paolo.
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