GCC14 libstdc++: multiprecision/number.hpp redefines class std::numeric_limits<__float128>

[jamborm]

With (development version) of GCC 14 and its libstdc++ (after commit https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=f150a084e25 ), attempting to compile a file which includes multiprecision/number.hpp such as plain

#include "/home/mjambor/boost/boost/libs/multiprecision/include/boost/multiprecision/number.hpp"

fails with:

mjambor@virgil:/tmp/zzz$ ~/gcc/trunk/inst/bin/g++ -I /home/mjambor/boost/boost t2.cc -S
In file included from /home/mjambor/boost/boost/boost/cstdfloat.hpp:22,
                 from /home/mjambor/boost/boost/boost/multiprecision/detail/float128_functions.hpp:15,
                 from /home/mjambor/boost/boost/boost/multiprecision/detail/fpclassify.hpp:13,
                 from /home/mjambor/boost/boost/boost/multiprecision/detail/default_ops.hpp:15,
                 from /home/mjambor/boost/boost/boost/multiprecision/detail/generic_interconvert.hpp:12,
                 from /home/mjambor/boost/boost/libs/multiprecision/include/boost/multiprecision/number.hpp:12,
                 from t2.cc:1:
/home/mjambor/boost/boost/boost/math/cstdfloat/cstdfloat_limits.hpp:46:13: error: redefinition of ‘class std::numeric_limits<__float128>’
   46 |       class numeric_limits<boost::math::cstdfloat::detail::float_internal128_t>
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/mjambor/boost/boost/boost/limits.hpp:19,
                 from /home/mjambor/boost/boost/boost/integer_fwd.hpp:16,
                 from /home/mjambor/boost/boost/boost/integer.hpp:18,
                 from /home/mjambor/boost/boost/boost/multiprecision/detail/standalone_config.hpp:52,
                 from /home/mjambor/boost/boost/libs/multiprecision/include/boost/multiprecision/number.hpp:10:
/home/mjambor/gcc/trunk/inst/include/c++/14.0.0/limits:2079:12: note: previous definition of ‘class std::numeric_limits<__float128>’
 2079 |     struct numeric_limits<__float128>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~

[mborland]

Confirmed and reported against Boost.Math here: boostorg/math#992.

[mborland]

Fixed by: boostorg/math#993