Visual Studio locking access to xml doc files

[eiriktsarpalis]

This is a common annoyance when using Visual Studio together with FAKE. Running a FAKE build while the solution is open in Visual Studio invariably results in the following error:

FSC : error FS0193: Access to the path 'path_to_bin_folder\project.XML' is denied. ['path_to_project\project.fsproj']

The error persists even if the solution is closed from within Visual Studio. The IDE needs to be restarted in order for the problem to go away.

[forki]

yes this is a major annoyance

[theimowski]

👍

[forki]

any ideas where we need to look?

[braden]

I have noticed this also happens occasionally when project files change externally and VS reloads them, unrelated to FAKE. I had suspected F# Power Tools, maybe there is something in common?

[dsyme]

I'd love to see this fixed, I've seen it somewhat randomly when compiling quite a range of projects with Visual F#.

[ovatsus]

I've also seen this. On F# Data I went to some trouble to try to not lock the .dll files, but then the .xml file is still locked :/
fsprojects/FSharp.Data@8734a17

[latkin]

Curious - does this seem to affect only F#, or has anyone experienced it with C#, too? Would also be good to know if this is a long-standing problem, or has this been the case for multiple VS releases?

[ovatsus]

This problem has existed at least since VS2012, and I never saw it in C#

[dungpa]

According to this answer http://stackoverflow.com/questions/6515795/why-is-my-xml-doc-file-always-getting-locked, this code fragment supposes to fix the bug https://github.com/Microsoft/visualfsharp/blob/fac44095a8dbc7303efa9866e0e2d9dddbdeae5d/vsintegration/src/vs/FsPkgs/FSharp.Project/Common.Source.CSharp/Project/ProjectConfig.cs#L1877-L1896. I'm not sure there is any regression here. Is there any historical note elsewhere about this bug?

For now, this answer seems like a reasonable workaround http://stackoverflow.com/a/3969978.

[rojepp]

@dungpa If I understand that fix correctly, it fixes for for building in VS only:
When a build starts, ask intellisense to stop locking xml doc. After build is finished, tell intellisense that its ok to lock this file again. This means building from command line will never work properly. How can we tell intellisense to never lock this file?

[dungpa]

@rojepp

How can we tell intellisense to never lock this file?

No idea. I don't understand why it needs to lock xml files in the first place.

@vladima @KevinRansom @latkin Any pointer to investigate this further?

[latkin]

Ok, just investigated a bit. This repros for C#, as well, at least as far back as VS 2013.

Steps:

• Create C# library project, add some XML doc comments, make sure project setting to generate doc file is enabled
• Build, then close VS
• Create new VS C# project, reference built binary from earlier.
• Use editor to view XML doc comments via intellisense
• Try re-building original project on command line via MSBuild
  • This fails due to XML doc file locked

So at least F# is not doing anything worse than C# here.

That's not to say this couldn't in theory be fixed (for all languages). Seems that project systems don't actually touch the XML doc files themselves, they rely on VS platform to handle this (lots of complexities around path to localized XML files, etc). Code here is using IVsXMLMemberIndexService. So the bug (and the fix) is somewhere in the VS platform/SDK, not in the F# codebase.

Maybe I will log a bug on the platform team to look at this.

[rojepp]

@latkin Please do file a bug and report any progress back here. :)