Source Generators fail in WinUI 3 projects because Csc is invoked with AnalyzerConfigFiles #52306

Copied from https://github.com/dotnet/roslyn/issues/52306. See follow-up comments in that issue where it is indicated this would be a better place to put it. (Or maybe not?)

Describe the bug

A project reunion project fails to build when it contains code that relies on a Source Generator in any of the XAML code-behind files.

Steps to reproduce the bug

(based on @dotMorten’s report https://github.com/microsoft/CsWin32/issues/219#issuecomment-811272354

Minimal repro solution

Or manual steps:

Install Project Reunion Project Templates: https://marketplace.visualstudio.com/items?itemName=ProjectReunion.MicrosoftProjectReunion Create a new Blank App, Packaged (WinUI 3 in Desktop) project. Install the Microsoft.Windows.CsWin32 nuget package (0.1.422-beta) Add NativeMethods.txt and some interop methods to it. Open MainWindow.xaml.cs, and in the constructor add a pinvoke method call. Compile Observe errors in the error list Using VS16.10.p1

Expected behavior

The build is successful.

Analysis

Examining the build log I’ve found the problem: The XamlPreCompile target as defined in MSBuild\Current\Bin\Microsoft.CSharp.CurrentVersion.targets invokes the Csc task but omits AnalyzerConfigFiles that is normally passed in. As a result, the CsWin32 source generator is not getting the info it needs to generate the APIs referenced in the XAML code-behind.

Screenshots

The CoreCompile target’s invocation of Csc: image

XamlPreCompile target’s invocation of Csc: image

[andrewleader]

Thanks @dotMorten, transferring this to WinUI to take the first stab

[agc93]

@RealTommyKlein I am still running into it but I’m on 16.11.0 Preview 3. I’ll try again with the non-Preview bits.

EDIT: you’re right that v16.11.1 non-Preview worked fine for me so maybe I was just missing an update