Building WinUI app under .NET 6 results in build error

[dellis1972]

Issue Description

Building a WinUI app under .NET 6 results in the following error

error MSB4062: The "Microsoft.Build.Tasks.GetInstalledSDKLocations" task could not be loaded from the assembly Microsoft.Build.Tasks.Core, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a.  Confirm that the <UsingTask> declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask.

Steps to Reproduce

Its difficult to reproduce because dotnet build support for WinUI is currently in progress. However the attached binlog should contain the required data.

msbuild.binlog.zip

Expected Behavior

GetInstalledSDKLocations should be available under .NET 6

Actual Behavior

The following build error

error MSB4062: The "Microsoft.Build.Tasks.GetInstalledSDKLocations" task could not be loaded from the assembly Microsoft.Build.Tasks.Core, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a.  Confirm that the <UsingTask> declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask.

Analysis

It looks like this Task was removed from the Core build of Microsoft.Build.Tasks.Core.

Versions & Configurations

dotnet --version
6.0.201

[dellis1972]

Also missing is ResolveSDKReferences.

[eerhardt]

@rainersigwald - do you know why GetInstalledSDKLocations is only compiled on .NET Framework?

msbuild/src/Tasks/Microsoft.Build.Tasks.csproj

Lines 545 to 602 in 3ade642

	<ItemGroup Condition="$(TargetFrameworkIdentifier) == '.NETFramework'">
	<Compile Include="Al.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AppDomainIsolatedTaskExtension.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AspNetCompiler.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AssemblyDependency\GacResolver.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AssemblyDependency\GlobalAssemblyCache.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AssemblyRegistrationCache.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AxImp.cs" />
	<Compile Include="AxReference.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AxTlbBaseReference.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="AxTlbBaseTask.cs" />
	<Compile Include="ComDependencyWalker.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReference.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReferenceInfo.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReferenceItemAttributes.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReferenceResolutionException.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReferenceTypes.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="ComReferenceWrapperInfo.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="GenerateBootstrapper.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="GenerateTrustInfo.cs" Condition="'$(MonoBuild)' != 'true'">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="GetFrameworkSDKPath.cs">
	<ExcludeFromStyleCop>true</ExcludeFromStyleCop>
	</Compile>
	<Compile Include="GetInstalledSDKLocations.cs" />

[rainersigwald]

@eerhardt No particularly good reason. We plan to fix for 17.3.

(The reason is "it wasn't needed until now and there was some roadblock porting it to .NET Core pre-1.0 so we just didn't".)

[eerhardt]

Hopefully 🤞 this is the last change needed for WinUI (and Maui Windows) apps to work correctly with dotnet build. We have it working if we skip the steps that need GetInstalledSDKLocations (which Maui does by default today with https://github.com/dotnet/maui/pull/5923/files#diff-2fda9742af9d1dcd9809679145355f4775b31715e2f879d2f765375867ee1b1eR7).

[sude22]

It would be very welcome if this error would be investigated.
Currently it is not possible to deloy a WinUI3 App unpacked as SingleFile via CI/DevOps.
Neither with msbuild nor with dotnet publish.

[rainersigwald]

@sude22 can you please file a new issue describing your problems in that scenario when using msbuild.exe to build? If that's not working, this issue doesn't track the fix.