Build intermittently fails due to missing generated source files

[davkean]

• .NET Core Version: Version: 3.0.0-preview7-27902-19
• Windows version: 18362.239

Problem description:
We've been intermittently hitting build failures in recent builds due to files usually generated by the XAML compiler missing. It will fail one time and immediately succeed next build and then won't fail against for a couple of hours. Multiple folks have started hitting it.

I happened to capture a failure under a build log.

Actual behavior:

CSC : error CS2001: Source file 'C:\project-system\artifacts\Debug\obj\Microsoft.VisualStudio.ProjectSystem.Managed.VS\ProjectSystem\VS\PropertyPages\GetProfileNameDialog.g.cs' could not be found. [C:\project-system\src\Microsoft.VisualStudio.ProjectSystem.Managed.VS\Microsoft.VisualStudio.ProjectSystem.Managed.VS_doj0ahs0_wpftmp.csproj]
CSC : error CS2001: Source file 'C:\project-system\artifacts\Debug\obj\Microsoft.VisualStudio.ProjectSystem.Managed.VS\ ProjectSystem\VS\PropertyPages\DebugPageControl.g.cs' could not be found. [C:\project-system\src\Microsoft.VisualStudio .ProjectSystem.Managed.VS\Microsoft.VisualStudio.ProjectSystem.Managed.VS_doj0ahs0_wpftmp.csproj]

Expected behavior:
No build failures.

Minimal repro:
Build Log: Build.zip

[davkean]

tag @drewnoakes

[vatsan-madhavan]

• Are these related to design time builds in anyway?
• Is this problem new to .NET Core 3.0 or does/did it happen in .NET Framework as well?
• Is this limited to IDE builds? If so, is the VS IDE calling build in a unique way?
  • If this might be related to design-time builds, is there a chance that the IDE is not to setting BuildingInsideVisualStudio ? See WinFx.targets

[davkean]

These are command-line builds, I've seen them inside Visual Studio. They appear to be regressions as I've not seen them before and this code has not changed in a long time.

Unsure if we're hitting this in design-time builds, we populate the error list from both and haven't paid attention to where its coming from.

[davkean]

I forgot to mention, we're using .NET SDK + .NET Framework targets, so this may be a bad interaction there.

[davkean]

As a side note, the build log will tell what properties, etc are being set.

[grubioe]

@ryalanms can you investigate? Thanks

[vatsan-madhavan]

@ryalanms do we have updates on this?

/cc @dotnet/wpf-developers

[ryalanms]

@davkean, could you share a project that reproduces the problem? From what I understand, Visual Studio does not support multi-targeted projects. Are any single projects building for both .NET Core and .NET Framework? I haven't been able to reproduce the problem locally. Thanks.

[davkean]

@ryalanms None of these projects are multi-targeting, but VS does support multi-targeting projects. In fact the project that is hitting the bug adds said multi-targeting support to VS. :)

This is also outside of Visual Studio via the command-line.

The solution is http://github.com/dotnet/project-system, but its very very inconsistent. Does the build log not give insights into this?