```
[ 50%] Building CXX object CMakeFiles/Algebraic_kernel_d_2.dir/Algebraic_kernel_d_2.cpp.o
/usr/local/bin/c++ -DCGAL_TEST_SUITE=1 -DCGAL_USE_CORE=1 -DCGAL_USE_GMP -DCGAL_USE_GMPXX -DCGAL_USE_MPFI -DCGAL_USE_MPFR -I/home/cgal_tester/build/src/cmake/platforms/Ubuntu-latest-GCC6-Release/test/Algebraic_kernel_d/include -isystem /usr/include/x86_64-linux-gnu -I/home/cgal_tester/build/src/cmake/platforms/Ubuntu-latest-GCC6-Release/test/Algebraic_kernel_d -I/home/cgal_tester/build/src/cmake/platforms/Ubuntu-latest-GCC6-Release/include -I/mnt/testsuite/include -DDONT_USE_BOOST_PROGRAM_OPTIONS -Wall -Wextra -O3 -DCGAL_NDEBUG -frounding-math -Wall -frounding-math -o CMakeFiles/Algebraic_kernel_d_2.dir/Algebraic_kernel_d_2.cpp.o -c /home/cgal_tester/build/src/cmake/platforms/Ubuntu-latest-GCC6-Release/test/Algebraic_kernel_d/Algebraic_kernel_d_2.cpp
In file included from /mnt/testsuite/include/CGAL/Polynomial.h:44,
from /mnt/testsuite/include/CGAL/Algebraic_kernel_d_1.h:37,
from /mnt/testsuite/include/CGAL/Algebraic_kernel_d_2.h:31,
from /home/cgal_tester/build/src/cmake/platforms/Ubuntu-latest-GCC6-Release/test/Algebraic_kernel_d/Algebraic_kernel_d_2.cpp:25:
/mnt/testsuite/include/CGAL/Handle_with_policy.h: In member function 'void CGAL::Curve_pair_analysis_2<AlgebraicKernelWithAnalysis_2>::compute_event_x_coordinates_with_event_indices() const [with AlgebraicKernelWithAnalysis_2 = CGAL::Algebraic_curve_kernel_2<CGAL::Algebraic_kernel_d_1<CORE::BigInt, CORE::BigRat, CGAL::internal::Algebraic_real_rep<CORE::BigInt, CORE::BigRat>, CGAL::internal::Descartes<CGAL::Polynomial<CORE::BigInt>, CORE::BigRat> > >]':
/mnt/testsuite/include/CGAL/Handle_with_policy.h:1014:28: warning: '*((void*)&<anonymous> +8)' may be used uninitialized in this function [-Wmaybe-uninitialized]
1014 | Handle_policy::find( h);
| ~~~~~~~~~~~~~~~~~~~^~~~
/mnt/testsuite/include/CGAL/Handle_with_policy.h:1014:28: warning: '*((void*)&<anonymous> +8)' may be used uninitialized in this function [-Wmaybe-uninitialized]
1014 | Handle_policy::find( h);
| ~~~~~~~~~~~~~~~~~~~^~~~
/mnt/testsuite/include/CGAL/Handle_with_policy.h:1014:28: warning: '*((void*)&<anonymous> +8)' may be used uninitialized in this function [-Wmaybe-uninitialized]
1014 | Handle_policy::find( h);
| ~~~~~~~~~~~~~~~~~~~^~~~
```
The warning is because an uninitialized `optional` is copied (in a
`push_back()`). The fix is to use `emplace_back()` to construct it
directly in the vector, instead of copying it.
Those two versions have a bug in memory allocation. The bug appears when
changing the allocation functions back and forth. In the beginning, MPFR
3.1.4 and 3.1.5 gather the GMP allocation functions and always use them. If
they are changed, MPFR does never notice that. This behavior was removed in
a patch to 3.1.5, what means that everything should be OK with MPFR 3.2.0.