Remove race condition from DllImportGenerator build

[jkoritzinsky]

We had a race condition in the DllImportGenerator build due to the workaround implemented for Roslyn 4.0 RC1's new assembly loading scheme. RC2 has a fix that should work to enable us to remove the workaround.

Fixes#61687

[ghost]

Tagging subscribers to this area: @Anipik, @safern, @ViktorHofer
See info in area-owners.md if you want to be subscribed.

Issue Details

---

We had a race condition in the DllImportGenerator build due to the workaround implemented for Roslyn 4.0 RC1's new assembly loading scheme. RC2 has a fix that should work to enable us to remove the workaround.

Fixes #61687

Author:	jkoritzinsky
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-

[jkoritzinsky]

It looks like the Roslyn bug that I was working around didn't get fixed until after the RC2 release, so this fix as-is depends on the 6.0 RTM SDK update.

I'll try to figure out another fix that works in both VS and at the command line, but it might take a bit

[trylek]

I just checked on the [succeeding] leg I retried in the originally failing run and I clearly see in the log that the DllImportGenerator project gets built twice - perhaps it's a dumb idea but wouldn't it be possible to just somehow deduplicate this at the build script level?

 WindowsBase -> D:\a\_work\1\s\artifacts\bin\WindowsBase\net7.0-Release\WindowsBase.dll
System.Private.CoreLib.Generators -> D:\a\_work\1\s\artifacts\bin\System.Private.CoreLib.Generators\netstandard2.0-Release\System.Private.CoreLib.Generators.dll
Microsoft.Interop.SourceGeneration -> D:\a\_work\1\s\artifacts\bin\Microsoft.Interop.SourceGeneration\netstandard2.0-Release\Microsoft.Interop.SourceGeneration.dll
DllImportGenerator -> D:\a\_work\1\s\artifacts\bin\DllImportGenerator\netstandard2.0-Release\Microsoft.Interop.DllImportGenerator.dll
DllImportGenerator -> D:\a\_work\1\s\artifacts\bin\DllImportGenerator\netstandard2.0-Release\Microsoft.Interop.DllImportGenerator.dll
System.Collections.Specialized -> D:\a\_work\1\s\artifacts\bin\System.Collections.Specialized\net7.0-Release\System.Collections.Specialized.dll
System.Collections.NonGeneric -> D:\a\_work\1\s\artifacts\bin\System.Collections.NonGeneric\net7.0-Release\System.Collections.NonGeneric.dll

[jkoritzinsky]

We could try to deduplicate it, but we'd be relying on "private" MSBuild semantics in the implementation of ProjectReferences.

[jkoritzinsky]

I was able to hack something together that should work. It's not the cleanest, but since I'm going to remove the workaround next month, we should be fine.

[trylek]

Looks great to my limited understanding, thanks for providing the stopgap fix!

[jkoritzinsky]

There's still another race here apparently (just hit it locally). Back to the drawing board I guess.

[jkoritzinsky]

Got another design. This one should avoid the case that caused a race condition in my last attempt.

[trylek]

Sounds like a solid design for the temporary workaround, thanks Jeremy; LGTM to the extent of my still limited understanding of Roslyn generators (after all that's why I asked you to take an initial look in the first place).

[safern]

LGTM, I'm glad this is just temporary 😄

[MichalStrehovsky]

I just hit a race with what's in main right now. Clean enlistment/deleted artifacts, followed by build.cmd libs -rc Release.

C:\Program Files\dotnet\sdk\6.0.100-rc.2.21505.57\Microsoft.Common.CurrentVersion.targets(3264,5): error MSB3554: Cannot write to the output file "C:\git\runtime2\artifacts\obj\Microsoft.Interop.SourceGeneration\netstandard2.0-Release\Microsoft.Interop.Resources.resources". The process cannot access the file 'C:\git\runtime2\artifacts\obj\Microsoft.Interop.SourceGeneration\netstandard2.0-Release\Microsoft.Interop.Resources.resources' because it is being used by another process. [C:\git\runtime2\src\libraries\System.Runtime.InteropServices\gen\Microsoft.Interop.SourceGeneration\Microsoft.Interop.SourceGeneration.csproj]
CSC : error CS1566: Error reading resource 'Microsoft.Interop.Resources.resources' -- 'Could not find file 'C:\git\runtime2\artifacts\obj\Microsoft.Interop.SourceGeneration\netstandard2.0-Release\Microsoft.Interop.Resources.resources'.' [C:\git\runtime2\src\libraries\System.Runtime.InteropServices\gen\Microsoft.Interop.SourceGeneration\Microsoft.Interop.SourceGeneration.csproj]

Rolling back the commit associated with this pull request unblocked me.