Compilation error on Windows with VS2022 and C++ 20

[olivier-roussel]

I'm trying to integrate proxsuite into the SOFA framework and more specifically the SoftRobots.Inverse plugin.
The SOFA CI on Windows is based on the MSVC CL compiler (v19.42) from Visual Studio 2022 toolkit. Also, SOFA now requires C++20 standard support.
When trying to compile using proxsuite with this build chain, I ran into this kind of error:

   Microsoft (R) C/C++ Optimizing Compiler Version 19.42.34435 for x64
  Copyright (C) Microsoft Corporation.  All rights reserved.
  cl /c /ID:\a\proxsuite\proxsuite\build /ID:\a\proxsuite\proxsuite\build\include /ID:\a\proxsuite\proxsuite\include /ID:\a\proxsuite\proxsuite\bindings\python\external\nanobind\include /W3 /WX- /diagnostics:column /MP /O2 /Ob2 /Os /D _WINDLL /D _MBCS /D _SCL_SECURE_NO_WARNINGS /D _CRT_SECURE_NO_WARNINGS /D _CRT_SECURE_NO_DEPRECATE /D WIN32 /D _WINDOWS /D NDEBUG /D PYTHON_MODULE_NAME=proxsuite_pywrap /D PROXSUITE_PYTHON_INTERFACE_WITH_OPENMP /D NOMINMAX /D Py_GIL_DISABLED=1 /D "CMAKE_INTDIR=\"Release\"" /D proxsuite_pywrap_EXPORTS /EHsc /MD /GS /fp:precise /Zc:wchar_t /Zc:forScope /Zc:inline /GR /openmp /std:c++20 /permissive- /Fo"proxsuite_pywrap.dir\Release\\" /Fd"proxsuite_pywrap.dir\Release\vc143.pdb" /external:W0 /Gd /TP /wd4101 /wd4250 /wd4251 /wd4275 /wd4355 /errorReport:queue  /external:I "D:/a/proxsuite/proxsuite/external/cereal/include" /external:I "C:/Users/runneradmin/miniconda3/envs/proxsuite/Include" /external:I "C:/Users/runneradmin/miniconda3/envs/proxsuite/Library/include/eigen3" /Zc:__cplusp
  expose-all.cpp
D:\a\proxsuite\proxsuite\include\proxsuite\linalg\veg\util\defer.hpp(43,1): error C2061: syntax error: identifier '__VEG_PP_TAIL' [D:\a\proxsuite\proxsuite\build\bindings\python\proxsuite_pywrap.vcxproj]
  (compiling source file '../../../bindings/python/src/expose-all.cpp')

See full log here: https://github.com/olivier-roussel/proxsuite/actions/runs/12912111683/job/36006147877#step:14:343

Unfortunately, SOFA framework does not support yet compilation on Windows using the Clang-cl compiler, which seems to be how proxsuite handles for now the C++20 standard support.

Do you have any hint or perspectives on how to handle this bug ?

[jorisv]

This build issue can be fixed by setting the /Zc:preprocessor compile option.

I don't think it's a good idea to add this definition, because it will propagate to consumers. I will try to find which macro should be patched instead…

[olivier-roussel]

Close as solved in #368. Thanks !