2019.1.3f1 IL2CPP broken: file name too long

After upgrading my testing project to 2019.1.3f1, I'm no longer able to build with il2cpp.
The following error gets thrown every time:

Code (CSharp):

1.  
2. il2cpp.exe didn't catch exception: Unity.IL2CPP.Building.BuilderFailedException: Lump_libil2cpp_icalls.cpp
3. C:\b\1\gdk-for-unity-blank-project-premerge\workers\unity\Temp\StagingArea\Data\il2cppOutput\lumpedcpp\Lump_libil2cpp_icalls.cpp(2): fatal error C1081: 'c:\b\1\gdk-for-unity-blank-project-premerge\workers\unity\temp\stagingarea\data\il2cppoutput\lumpedcpp\..\..\..\..\..\..\..\..\..\..\Program Files\Unity\Editor\Data\il2cpp\libil2cpp\icalls\System.Configuration\System.Configuration\InternalConfigurationHost.cpp': file name too long
4.  

Does anyone have a suggestion as to how to work around this problem?

 

What happens if you move the build directory to the root of the drive?

I suggest filing a bug for this issue.

 

Sadly I'm unable to move the folder, as this is run on our CI. I'll be trying to run it locally today. Will also be trying to reproduce this with the project on another drive (so it cannot be relative).

 

Just to give a quick update, it was a unity bug in the end.
Filed bug case 1156443

The issue is that generated cpp files which include files from your unity editor folder, will use paths relative from your project folder, if unity is installed on the same drive as your project.
This causes the expanded path to be something like C:\my\project\dir\..\..\..\Program File\Unity\etc etc as seen in the error above.