MSBuild 2019 ignores INCLUDE environment variable - c++

Question

I am working with two machines that have Visual Studio 2019. One has Community edition, the other has Pro edition.
The pro edition of MSBuild is completely ignoring the INCLUDE environment variable, so the project I'm trying to build (ICU) cannot find stddef.h. The stddef.h file is in the Windows Kits 10 ucrt directory, which is included in the INCLUDE env var.
The community edition doesn't do this.
When I build the project with the /v:diag option I can see most of what's defined in the INCLUDE env var is added to a variable named CAExcludePath.
Here's the INCLUDE env var: INCLUDE=C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.24.28314\include;;C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.24.28314\atlmfc\include;;C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Auxiliary\VS\include;;C:\Program Files (x86)\Windows Kits\10\Include\10.0.10240.0\ucrt;;;C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Auxiliary\VS\UnitTest\include;C:\Program Files (x86)\Windows Kits\8.1\Include\um;C:\Program Files (x86)\Windows Kits\8.1\Include\shared;C:\Program Files (x86)\Windows Kits\8.1\Include\winrt;;
And here's the CAExcludePath: CAExcludePath=C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.24.28314\atlmfc\include;C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.24.28314\include;C:\Program Files (x86)\Windows Kits\10\Include\10.0.10240.0\ucrt;;C:\Program Files (x86)\Windows Kits\8.1\Include\um;C:\Program Files (x86)\Windows Kits\8.1\Include\shared;C:\Program Files (x86)\Windows Kits\8.1\Include\winrt;;
Why does this happen and how do I prevent it?

Answer 1

MSBuild 2019 ignores INCLUDE environment variable
I think you should not set these paths into Environment Variables. For C++ projects, VS does not recognize the library path in system environment variables by default and this is not the VS job.
Usually, you should set extra library paths in VS IDE. Right-click on your project-->Properties-->Configuration Properties-->VC++ Directories-->Include Directories or Properties-->Configuration Properties-->C/C++-->Additional Include Directories. You can refer to this official document.
However, when l install Windows Kits tool, this path is included in the include path by default and you can use this in your code directly. See this:
So l am afraid you have something wrong when you install the Windows Kits tool. Please follow this document to install the right tool and before you finish it, please install the related extension which is the last step in the installer in Visual Studio 2019 to integrate the tool.
I think when you install the extension, these paths will be included into VS automatically and you can use them directly.
Besides, if you do not want to install this extension, you can add the include path manually by the steps I mentioned above.
If you have done these steps and still faced the same error, I think you should check your Environment and follow these suggestions:
1) close VS Instance, delete .vs, bin, obj folders,reopen your project and then build again
2) do a repair in VS Installer
3) if your VS is not the latest, please update your VS and do not forget to update Operation System at the same time.
Hope these help.

Answer 2

Use the IncludePath environment variable instead.
set IncludePath=%INCLUDE%
IncludePath is not ignored/overwritten when running msbuild, and I was able to successfully compile my project/solution by setting it.
On my machine, setting IncludePath overrides 3 paths which would otherwise be set. The 3 paths have analogs (same header files but for different versions) in my %INCLUDE% paths, so it seems safe (and in fact prudent) to ignore/clobber/leave these out.