error CS8784: Generator 'DownlevelLibraryImportGenerator' failed to initialize on osx-arm64

[am11]

On osx-arm64, using current tip of main 5c4686f from clean state:

$ dotnet nuget locals all --clear

$ cd runtime
$ git clean -xdf
$ git rev-parse HEAD
5c4686f831d34c2c127e943d0f0d144793eeb0ad

$ ./build.sh clr+libs -c Release
...
  Restored /Users/adeel/projects/runtime5/src/coreclr/tools/SuperFileCheck/SuperFileCheck.csproj (in 59,59 sec).
  Restored /Users/adeel/projects/runtime5/src/native/managed/cdacreader/src/cdacreader.csproj (in 1,79 min).
  Restored /Users/adeel/projects/runtime5/src/coreclr/tools/aot/ILCompiler/ILCompiler.csproj (in 1,11 min).
  Restored /Users/adeel/projects/runtime5/src/coreclr/tools/r2rdump/R2RDump.csproj (in 1,18 min).
  Restored /Users/adeel/projects/runtime5/src/coreclr/tools/dotnet-pgo/dotnet-pgo.csproj (in 1,22 min).
  installer.tasks -> /Users/adeel/projects/runtime5/artifacts/bin/installer.tasks/Release/net9.0/installer.tasks.dll
  Crossgen2Tasks -> /Users/adeel/projects/runtime5/artifacts/bin/Crossgen2Tasks/Release/net9.0/Crossgen2Tasks.dll
  Microsoft.Interop.SourceGeneration -> /Users/adeel/projects/runtime5/artifacts/bin/Microsoft.Interop.SourceGeneration/Release/netstandard2.0/Microsoft.Interop.SourceGeneration.dll
  DownlevelLibraryImportGenerator -> /Users/adeel/projects/runtime5/artifacts/bin/DownlevelLibraryImportGenerator/Release/netstandard2.0/Microsoft.Interop.LibraryImportGenerator.Downlevel.dll
CSC : error CS8784: Generator 'DownlevelLibraryImportGenerator' failed to initialize. It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'FileNotFoundException' with message 'Could not load file or assembly 'Microsoft.Interop.SourceGeneration, Version=42.42.42.42, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the path specified. [/Users/adeel/projects/runtime5/src/tasks/installer.tasks/installer.tasks.csproj::TargetFramework=net472]

It is looking for net472. On, e.g. linux-arm64, it only looks for netstandard2.0 and does not fail:

  Restored /runtime/src/libraries/System.DirectoryServices/src/System.DirectoryServices.csproj (in 1.71 min).
  installer.tasks -> /runtime/artifacts/bin/installer.tasks/Release/net9.0/installer.tasks.dll
  Crossgen2Tasks -> /runtime/artifacts/bin/Crossgen2Tasks/Release/net9.0/Crossgen2Tasks.dll
  Microsoft.Interop.SourceGeneration -> /runtime/artifacts/bin/Microsoft.Interop.SourceGeneration/Release/netstandard2.0/Microsoft.Interop.SourceGeneration.dll
  DownlevelLibraryImportGenerator -> /runtime/artifacts/bin/DownlevelLibraryImportGenerator/Release/netstandard2.0/Microsoft.Interop.LibraryImportGenerator.Downlevel.dll
  installer.tasks -> /runtime/artifacts/bin/installer.tasks/Release/net472/installer.tasks.dll

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[am11]

@jkoritzinsky #106436 related.

[jkoritzinsky]

@am11 can you get a compilation log (using https://github.com/jaredpar/complog)?

[am11]

This is now fixed (perhaps since #107746).