BUGS.md

Known bugs affecting

This file is to list known bugs in Gyoto or its dependencies that significantly affect Gyoto but are not easy to fix or workaround in Gyoto.

Partial uninstallation of Python extension

After having installed and uninstalled Gyoto from source with "make uninstall", empty directories may remain in a Python dist-packages directory (typically /usr/local/lib/python3.??/dist-packages/), which causes subsequent installation of Python packages from source to fail (Gyoto and any other setuptools-based package). Make sure to remove such empty directories.

                    -- Thibaut Paumard, Mon Dec 09 2024.

Boost.multiprecision 1.62.0 (other nearby versions presumably affected):

A bug makes multiprecision acos() never return in some circumstances. This has caused gyoto hanging. As of writing, this is fixed in the Boost development tree and worked around in the Debian package for Gyoto. For further details and workarounds, see:

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=844490

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=844495

• https://svn.boost.org/trac/boost/ticket/12625

                  -- Thibaut Paumard, Thu Dec 08 2016.
  

Clang/LLVM compiler (all versions), possibly other compilers:

Gyoto relies on proper delivery of SIGFPE when arithmetic errors occur (division by zero, floating point overflows...). It does so by enabling the right exceptions using feenableexcept from GNU fenv.h.

However, some compilers (clang/llvm, in particular) do not support setting the floating-point environment and will happily optimize code assuming that it is safe to divide by zero. We recommend staying away from these compilers until this issue is fixed:

• https://llvm.org/bugs/show_bug.cgi?id=23707
• https://llvm.org/bugs/show_bug.cgi?id=8100

Alternatively, you may try to reconfigure Gyoto to not use fenv.h and/or to not use any optimization: make clean ./configure --without-fenv CFLAGS="-g -O0" CXXFLAGS="-g -O0" make and see whether it works better for you.

If you experience such spurious SIGFPE inside the Yorick plug-in, an ugly workaround is to call gyoto.fedisableexcept() right before the offending Gyoto call. If at all possible, consider recompiling Gyoto as explained above.

Note that loading some plug-ins (e.g. the lorene plug-in) may change or reset the default floating-point environment. This is the case if the plug-in, or one of the libraries it links with, has been compiled with optimizations such as -ffast-math or gfortran.

                    -- Thibaut Paumard, Thu Dec 08 2016.