Runtime windows verticals failing to build in the VMR

[ViktorHofer]

CSC : error CS0016: Could not write to output file 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComClassGenerator\Microsoft.Diagnostics.DataContractReader.SOSDacImpl.cs' -- 'Could not find a part of the path 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComClassGenerator\Microsoft.Diagnostics.DataContractReader.SOSDacImpl.cs'.' [D:\a_work\1\s\src\runtime\src\native\managed\cdacreader\src\cdacreader.csproj]
CSC : error CS0016: Could not write to output file 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Diagnostics.DataContractReader.ISOSDacInterface9.cs' -- 'Could not find a part of the path 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Diagnostics.DataContractReader.ISOSDacInterface9.cs'.' [D:\a_work\1\s\src\runtime\src\native\managed\cdacreader\src\cdacreader.csproj]

https://dnceng-public.visualstudio.com/public/_build/results?buildId=646322&view=logs&j=9050e078-31bf-5111-d8ec-8b6fa95caf9c&t=4df1dbeb-294c-5d6e-97b8-581fe506c270

@elinor-fung

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[jeffschwMSFT]

this is also impacting dotnet/runtime official build (though is non-deterministic)

https://dnceng.visualstudio.com/internal/_build/results?buildId=2430979&view=logs&j=bdec34cc-8c67-558e-657b-d36a4105119f&t=57c2fa6d-d2d0-5d36-e636-8657b10bc2de&l=599

[elinor-fung]

One thing I see between a working dotnet-runtime-official build and a failing one - for example 20240415.10 failure (binlog) versus
20240417.11 success (binlog) - is that the failing one has additional MSBuild command line arguments -p:UseSharedCompilation=false -p:EmitCompilerGeneratedFiles=true.

The build logs from the dotnet-unified-build 20240416.1 failure also shows that -p:EmitCompilerGeneratedFiles=true was passed on the command line.

The files in the error messages should only be written to disk by the source generator when EmitCompilerGeneratedFiles is true (defaults to false). I don't know what is (was?) including that property when invoking the build.

I'm not sure what the underlying cause is either. The cdacreader project is just using the COM source generator and those paths aren't long enough to be hitting any long path problems with source generators.

[elinor-fung]

@chsienki @dotnet/roslyn Any idea what could be leading to CS0016 during source generation with EmitCompilerGeneratedFiles=true? The path in the error message is under 256 characters, so I don't think it is hitting long path problems.

CSC : error CS0016: Could not write to output file 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComClassGenerator\Microsoft.Diagnostics.DataContractReader.SOSDacImpl.cs' -- 'Could not find a part of the path 'D:\a_work\1\s\src\runtime\artifacts\obj\cdacreader\Release\net9.0\win-x64\generated\Microsoft.Interop.ComInterfaceGenerator\Microsoft.Interop.ComClassGenerator\Microsoft.Diagnostics.DataContractReader.SOSDacImpl.cs'.'

Previous comment #4335 (comment) has links to binlogs.

[RikkiGibson]

Could not find a part of the path makes it sound like the output directory is not present. But the compiler and compiler tasks should create the directory (both the /generated directory and the individual generator output directories within it).

https://github.com/dotnet/roslyn/blob/d5b9aaa7e984890c9a8d967bde68d1c62d4858fa/src/Compilers/Core/MSBuildTask/Microsoft.Managed.Core.targets#L339-L340

https://github.com/dotnet/roslyn/blob/d5b9aaa7e984890c9a8d967bde68d1c62d4858fa/src/Compilers/Core/Portable/CommandLine/CommonCompiler.cs#L1173-L1176

However it looks like the task linked above didn't run in the cdacreader build. binlog says:

Target Name=CreateCompilerGeneratedFilesOutputPath Project=cdacreader.csproj
Target "CreateCompilerGeneratedFilesOutputPath" skipped, due to false condition; ('$(EmitCompilerGeneratedFiles)' == 'true' and !('$(DesignTimeBuild)' == 'true' OR '$(BuildingProject)' != 'true')) was evaluated as ('true' == 'true' and !('' == 'true' OR 'false' != 'true')).

I'm confused by this :) as 'true' == 'true' and !('' == 'true' OR 'false' != 'true') seems like it ought to evaluate to true. false, my conditional logic brain wasn't working. I think the BuildingProject property should be true instead of false in order for the directory to be created here. What controls that?

I think maybe the compiler task has a bug here. Basically it feels like we should only be passing a /generatedfilesout argument to the compiler if we also ran target CreateCompilerGeneratedFilesOutputPath. But it looks like the current build task permits us to pass that argument without running the target.

[chsienki]

@RikkiGibson Lol I just spent like a genuine 5 minutes working through the logic of that condition, then did a git blame to see who wrote it and well, well we meet again past Chris.

Something in the authoring is off definitely, but it also seems odd that the compiler still tries to write the files out, even if the directory isn't there, so we should probably file a bug on Roslyn for that.