The AnnotatorBuildTask task failed unexpectedly

[JohanLarsson]

Severity	Code	Description	Project	File	Line	Suppression State
Error	MSB4018	The "AnnotatorBuildTask" task failed unexpectedly.
System.IO.IOException: The process cannot access the file 'C:\Git\_GuOrg\Gu.Wpf.UiAutomation\Gu.Wpf.UiAutomation\obj\Debug\net45\annotated\mscorlib.dll' because it is being used by another process.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at Mono.Cecil.ModuleDefinition.Write(String fileName, WriterParameters parameters)
   at TunnelVisionLabs.ReferenceAssemblyAnnotator.Program.Main(Nullable`1 log, String referenceAssembly, String annotatedReferenceAssembly, String outputAssembly)
   at TunnelVisionLabs.ReferenceAssemblyAnnotator.AnnotatorBuildTask.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()	Gu.Wpf.UiAutomation	C:\Users\ds2346\.nuget\packages\tunnelvisionlabs.referenceassemblyannotator\1.0.0-alpha.77\build\TunnelVisionLabs.ReferenceAssemblyAnnotator.targets	60	

From the name I'm guessing it can be something in this nice package.
Repro in this commit https://github.com/GuOrg/Gu.Wpf.UiAutomation/tree/a5b789bf37742a9edd098d187d8a8362a80e43a8

I think I have only seen it after git clean and start Visual Studio

[jnm2]

I see this about once a day.

[jnm2]

@sharwell Should the annotator bail and assume that the only other process that will be causing this is another build of the same project, and that the file being written is what the annotator would have written anyway?

Or should it retry?

[jnm2]

This started happening repeatedly until I restarted VS.

[JohanLarsson]

Got this with 1.0.0-alpha.138. Repro: https://github.com/GuOrg/Gu.Wpf.ToolTips

Severity	Code	Description	Project	File	Line	Suppression State
Error	MSB4018	The "AnnotatorBuildTask" task failed unexpectedly.
System.IO.IOException: The file 'obj\Debug\netcoreapp3.1\annotated\Microsoft.CSharp.xml' already exists.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite, Boolean checkHost)
   at System.IO.File.Copy(String sourceFileName, String destFileName)
   at TunnelVisionLabs.ReferenceAssemblyAnnotator.AnnotatorBuildTask.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()	Gu.Wpf.ToolTips	C:\Users\ds2346\.nuget\packages\tunnelvisionlabs.referenceassemblyannotator\1.0.0-alpha.138\build\TunnelVisionLabs.ReferenceAssemblyAnnotator.targets	89	

[sharwell]

This is going to be possible in parallel build scenarios until file-system locking is used.

[jnm2]

I was going to say, I don't think it's project-specific. It crops up and requires a VS restart maybe once a day for me no matter what the project is.