Update of Visual Studio (17.6.2) and SDK (6.0.302) prevents the use of source generators for Microsoft.Toolkit.MVVM

[MarcoSpoenemann]

Describe the bug

After installing the updates, it is no longer possible to compile WPF projects using Microsoft.Toolkit.MVVM. Errors are thrown during the build process:

• The type already contains a definition for .
• Duplicate 'global::System.CodeDom.Compiler.GeneratedCode' attribute

and so on.

It looks like code generators are executed twice.

To Reproduce

Use the sample project in this repository with Visual Studio 17.2.6 and the latest .NET 6 SDK and try to build: https://github.com/MarcoSpoenemann/dotnet6-mvvm

Exceptions (if any)

• CS0101
• CS0579
• CS0102

Further technical details

.NET SDK (gemäß "global.json"):
Version: 6.0.302
Commit: c857713

Laufzeitumgebung:
OS Name: Windows
OS Version: 10.0.22000
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\6.0.302\

global.json file:
Not found

Host:
Version: 6.0.7
Architecture: x64
Commit: 0ec02c8c96

.NET SDKs installed:
2.2.402 [C:\Program Files\dotnet\sdk]
3.1.421 [C:\Program Files\dotnet\sdk]
5.0.102 [C:\Program Files\dotnet\sdk]
5.0.403 [C:\Program Files\dotnet\sdk]
5.0.408 [C:\Program Files\dotnet\sdk]
6.0.100 [C:\Program Files\dotnet\sdk]
6.0.107 [C:\Program Files\dotnet\sdk]
6.0.202 [C:\Program Files\dotnet\sdk]
6.0.203 [C:\Program Files\dotnet\sdk]
6.0.302 [C:\Program Files\dotnet\sdk]

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[Tum4ik]

A workaround is here dotnet/wpf#6792.

[Keboo]

Running into a similar problem on Material Desing in XAML Toolkit. It uses some source generators from XAMLTest which appear to be getting executed twice (or the output included twice). Rolling back the SDK with the global.json appears to fix the issue for now.

[marcpopMSFT]

This is the issue tracking the fix. dotnet/wpf#6792