Self-contained deployment of WinForms always includes WPF assemblies

Moved from https://github.com/dotnet/winforms/issues/2426. Related: https://github.com/mono/linker/issues/832

• .NET Core Version: 3.0; 3.1
• Have you experienced this same bug with .NET Framework?: No

Problem description:

• Create a simple WinForms application (either through dotnet new or VS)
• Add Publish profile, change it from “framework dependent” to “self-contained”
• Enable PublishTrimmed

Actual behavior:

Published output contains large part of WPF stack (eg. PresentationCore.dll, PresentationUI.dll, PresentationFramework*.dll, etc.) which amounts to over 30 Mb (> 10 Mb compressed) of unused assemblies. The files are pulled from the “runtimepack.Microsoft.WindowsDesktop.App.Runtime.win-x86/3.0.0” NuGet package.

Expected behavior:

No WPF assemblies in the output. They should either not be included or they should get trimmed out.

Minimal repro:

WindowsFormsApp1.zip

[AraHaan]

For .NET 6 and 5 When I specify UseWinForms to true in project it should exclude referencing the wpf assemblies entirely unless you also set UseWPF to true as well.

[NN---]

You can use explicit FrameworkReference to WindowsForms.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <!-- Use explicit  -->
    <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
  </PropertyGroup>


  <ItemGroup>
    <!-- .NET Runtime -->
    <FrameworkReference Include="Microsoft.NETCore.App" />
    
    <!-- Windows Forms -->
    <FrameworkReference Include="Microsoft.WindowsDesktop.WindowsForms”  />   
  </ItemGroup>

</Project>

I use this technique in my project to prevent adding Windows Forms assemblies to Console application https://habr.com/ru/post/549530/