Compilation errors on Visual Studio with C++20 standard about units

[phlptp]

I will take a look. Is this on the latest visual studio version? I had some trouble in the past with some breaking changes in C++20 and U8 strings, so this might be related to that.

[SimonHeybrock]

We are using the windows-latest CI image from Azure: https://github.com/scipp/scipp/blob/master/.azure-pipelines/pull_request.yml#L183. I am not sure how often this is updated, but right now versions are:

2021-02-08T14:11:22.5461743Z + cmake -G 'Visual Studio 16 2019' -A x64 -DCMAKE_CXX_STANDARD=20 -DPYTHON_EXECUTABLE=/c/Miniconda/envs/scipp-developer/python '-DCMAKE_INSTALL_PREFIX=D:\a\1\a/install' -DCMAKE_BUILD_TYPE=Release 'D:\a\1\s'
2021-02-08T14:11:48.4399026Z -- The C compiler identification is MSVC 19.28.29336.0
2021-02-08T14:11:50.6122933Z -- The CXX compiler identification is MSVC 19.28.29336.0

[phlptp]

Are you building with the Units CMAKE or just including the code in your library?
If you are just including the code you will need to include the /Zc:char8_t- flag on visual studio when compiling with C++20.
The CMAKE stuff includes that but I should add a note to the docs if just adding the code.

For other compilers you would need -fno-char8_t

[SimonHeybrock]

I am using this via cmake add_subdirectory, so if this is set by the CMakeLists.txt of Units, I suppose it should be handled correctly without manual intervention?

[phlptp]

Yeah it should be, if you want to check something try adding those flags to your project and see if it compiles. I might have put them in the wrong spot, or something that doesn't propagate under add_subdirectory

[SimonHeybrock]

I can confirm, this is fixed by #125. Thanks a lot for the quick response!