[PATCH] Define 3-argument overloads of std::hypot for C++17 (P0030R1)

[Jonathan Wakely]

On 29/09/16 10:54 +0200, Rainer Orth wrote:
>Hi Jonathan,
>
>> This adds the new 3D std::hypot() functions. This implementation seems
>> to be faster than the naïve sqrt(x*x + y*y + z*z) implementation, or
>> hypot(hypot(x, y), z), and should be a bit more accurate at very large
>> or very small values due to reducing the arguments by the largest one.
>> Improvements welcome though, as this is not my forte.
>>
>> The test might not be very good, but tests some small integer values
>> and some other values where accuracy is lost for one or other of the
>> alternative implementations mentioned above. If this FAILs for some
>> 32-bit targets we might need to adjust the tolerances or the
>> dg-options.
>>
>> 	* doc/xml/manual/status_cxx2017.xml: Update status.
>> 	* include/c_global/cmath (hypot): Add three-dimensional overloads.
>> 	* testsuite/26_numerics/headers/cmath/hypot.cc: New.
>>
>> Tested powerpc64le-linux and x86_64-linux, committed to trunk.
>
>the new test currently FAILs on Solaris 12 (both SPARC and x86):
>
>+FAIL: 26_numerics/headers/cmath/hypot.cc (test for excess errors)
>+WARNING: 26_numerics/headers/cmath/hypot.cc compilation failed to produce execu
>table
>
>Excess errors:
>/vol/gcc/src/hg/trunk/local/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc:38: error: no matching function for call to 'hypot(double, double, double)'
>/vol/gcc/src/hg/trunk/local/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc:38: error: no matching function for call to 'hypot(double, double, double)'
>/vol/gcc/src/hg/trunk/local/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc:38: error: template argument 2 is invalid
>
>and many more.

That would suggest Solaris uses include/c_std/cmath (where I forgot to
add the new overloads) rather than include/c_global/cmath ... is that
right?