KnownFrameworkReferences need to be specific to a target framework version

[dsplaisted]

Right now, we have KnownFrameworkReference items that look something like this in Microsoft.NETCoreSdk.BundledVersions.props:

    <KnownFrameworkReference Include="Microsoft.DesktopUI"
                              RuntimeFrameworkName="Microsoft.DesktopUI.App"
                              DefaultRuntimeFrameworkVersion="3.0.0-alpha-26829-8"
                              LatestRuntimeFrameworkVersion="3.0.0-alpha-26829-8"
                              TargetingPackName="Microsoft.DesktopUI.App"
                              TargetingPackVersion="3.0.0-alpha-26829-8"
                              />

    <KnownFrameworkReference Include="Microsoft.AspNetCore"
                              RuntimeFrameworkName="Microsoft.AspNetCore.App"
                              DefaultRuntimeFrameworkVersion="3.0.0-alpha1-10062"
                              LatestRuntimeFrameworkVersion="3.0.0-alpha1-10062"
                              TargetingPackName="Microsoft.AspNetCore.App"
                              TargetingPackVersion="3.0.0-alpha1-10062"
                              />

These are not specific to the version of .NET Core targeted. So if you were targeting .NET Core 2.x, you could still add a FrameworkReference to Microsoft.DesktopUI, and we would try to add the package reference to the targeting pack.

The KnownFrameworkReference items should include a TargetFrameworkVersion on them to which they apply, and the ResolveFrameworkReferences task should filter them to only look at the ones that apply to the current target framework version. (We might also want a nice error message if you have a FrameworkReference to something that's available in a different version of .NET Core).

[nkolev92]

I'm curious how the FrameworkReference to TFM mapping will affect NuGet and NuGet/Home#7342.

What would the experience be if someone adds a FrameworkReference to DesktopUI and has net46 as a TFM etc.