SDK-style WPF Projects targeting net472 are broken because ImportFrameworkWinFXTargets is false

[KirillOsenkov]

This PR has regressed building WPF projects that use the SDK-style:
#2976

By default ImportFrameworkWinFXTargets was true, but now changes to false, resulting in MarkupCompile not running.

FYI @Nirmal4G

[KirillOsenkov]

so just upgrading the SDK from 5 to 6 will break the build in a very confusing way

[Nirmal4G]

Even if it is set as false, the .NET SDK should reset it to true based on the TargetFramework. Let me take a look…

[KirillOsenkov]

It wasn't set to anything in my codebase, and setting it to true in my Directory.Build.props fixed it.

Just create a new SDK-style .csproj, target net472 only, add some WPF references (PresentationCore, PresentationFramework, System.Xaml and WindowsBase), create a new Application and Window in Main() and build.

[KirillOsenkov]

This is the line that sets it to false (whereas otherwise it is true for me):
https://github.com/dotnet/wpf/pull/2976/files#diff-5827fafdcece80f275068609904789952b21a8e75ae7b3fcb6b0fd39b3d0d0b5R171

[vatsan-madhavan]

IIRC WPF SDK was using the SDK’s WinFx props/Targets (it has a props too), PresentationBuildTasks etc even when building NetFx targets. That has been the behavior since sometime in 3.x. NetFx targets do not use NetFx’s copy of targets or tasks.

Not sure if the regression implicates this or not but figured I’d put this out there to help with the investigation.

See #2075

[Nirmal4G]

In .NET SDK's BeforeCommon.targets These Lines 49-56 reset it to true when targeting .NETFramework but doesn't do that! since, we set this in props in the Windows Desktop SDK. So, the solution here is, either remove the setting from the WindowsDesktop.props which may break projects or move the setting to Sdk.props and update the Main SDK logic to handle this case.

I recommend we move the setting to Sdk.props to preserve it's intended behavior—as it was meant be used only when using the Windows Desktop SDK directly. My PR was supposed to be merged before the v5 refactoring but was delayed. Meanwhile, I didn't know the logic was being updated in the Main SDK during that time.

I can go ahead and open a PR on what the team recommends.

[KirillOsenkov]

No worries at all, it’s hard not to break MSBuild and we do it all the time. Welcome to the club! And thanks for looking into this.

[vatsan-madhavan]

@dsplaisted fyi

[dsplaisted]

Yeah, it made sense to set this to false in WindowsDesktop.props when that was only imported if the project was explicitly using Microsoft.NET.Sdk.WindowsDesktop. But now we always import that props file.

You could move it to the WindowsDesktop Sdk.props file, I think that would work in both situations.

[ryalanms]

We need to fix this. @Nirmal4G: Are you going to create a PR or should someone from the WPF team get it? Thanks.

[Nirmal4G]

For now, Moving the logic to the SDK.props should work but a long-term fix should be using the SDK's WinFX targets instead of using the inbox targets and tasks!