Failure to build when Microsoft.WindowsAppSDK 1.6 referenced through secondary nuget package

[kjean667]

Describe the bug

With the latest WindowsAppSDK 1.6.240923002 it is impossible for a class library to consume a nuget package that references the WindowsAppSDK 1.6.240923002 nuget package.

Reproduction example code

The example consists of three projects:

• WebView2LoaderBug.Lib - A class library that uses the WindowsAppSDK 1.6.240923002 as a nuget reference and in itself builds a nuget package named WebView2LoaderBugLibrary.
• WebView2LoaderBug.LibWrapper - A class library that references the WebView2LoaderBugLibrary nuget package built by the WebView2LoaderBug.Lib project.
• WebView2LoaderBug.App - A WinUI 3 desktop application that references the WebView2LoaderBug.LibWrapper project.

The project fails to build the WebView2LoaderBug.Lib project with the following compiler error output:

1>------ Rebuild All started: Project: WebView2LoaderBug.Lib, Configuration: Debug Any CPU ------
Restored C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.LibWrapper\WebView2LoaderBug.LibWrapper.csproj (in 51 ms).
Restored C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.App\WebView2LoaderBug.App.csproj (in 70 ms).
Restored C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.Lib\WebView2LoaderBug.Lib.csproj (in 88 ms).
1>WebView2LoaderBug.Lib -> C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.Lib\bin\Debug\net8.0-windows10.0.22621\WebView2LoaderBug.Lib.dll
1>The package WebView2LoaderBugLibrary.1.0.0 is missing a readme. Go to https://aka.ms/nuget/authoring-best-practices/readme to learn why package readmes are important.
1>Successfully created package 'C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.Lib\bin\WebView2LoaderBugLibrary.1.0.0.nupkg'.
2>------ Rebuild All started: Project: WebView2LoaderBug.LibWrapper, Configuration: Debug Any CPU ------
2>C:\Program Files\Microsoft Visual Studio\2022\Professional\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets(5321,5): error MSB3030: Could not copy the file "C:\Users\my-user\.nuget\packages\webview2loaderbuglibrary\1.0.0\lib\net8.0-windows10.0.22621\WebView2LoaderBug.Lib\runtimes\win-arm64\native\WebView2Loader.dll" because it was not found.
2>C:\Program Files\Microsoft Visual Studio\2022\Professional\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets(5321,5): error MSB3030: Could not copy the file "C:\Users\my-user\.nuget\packages\webview2loaderbuglibrary\1.0.0\lib\net8.0-windows10.0.22621\WebView2LoaderBug.Lib\runtimes\win-x64\native\WebView2Loader.dll" because it was not found.
2>C:\Program Files\Microsoft Visual Studio\2022\Professional\MSBuild\Current\Bin\amd64\Microsoft.Common.CurrentVersion.targets(5321,5): error MSB3030: Could not copy the file "C:\Users\my-user\.nuget\packages\webview2loaderbuglibrary\1.0.0\lib\net8.0-windows10.0.22621\WebView2LoaderBug.Lib\runtimes\win-x86\native\WebView2Loader.dll" because it was not found.
2>Done building project "WebView2LoaderBug.LibWrapper.csproj" -- FAILED.
3>------ Rebuild All started: Project: WebView2LoaderBug.App, Configuration: Debug x86 ------
3>C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.App\WebView2LoaderBug.App.csproj : XamlCompiler error WMC1006: Cannot resolve Assembly or Windows Metadata file 'C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.LibWrapper\bin\Debug\net8.0-windows10.0.22621\WebView2LoaderBug.LibWrapper.dll'
3>CSC : error CS0006: Metadata file 'C:\Users\my-user\Documents\Develop\lab\WebView2LoaderBug\WebView2LoaderBug.LibWrapper\bin\Debug\net8.0-windows10.0.22621\WebView2LoaderBug.LibWrapper.dll' could not be found
3>Done building project "WebView2LoaderBug.App.csproj" -- FAILED.
========== Rebuild All: 1 succeeded, 2 failed, 0 skipped ==========

The reason for using a class library wrapper to consume the nuget package is because of bug https://github.com/microsoft/microsoft-ui-xaml/issues/6429.

Steps to reproduce the bug

Try to compile the given reproduction example code.

Expected behavior

The solution shall compile without any errors.

Screenshots

No response

NuGet package version

Windows App SDK 1.6.1: 1.6.240923002

Packaging type

Packaged (MSIX)

Windows version

Windows 11 version 22H2 (22621, 2022 Update)

IDE

Visual Studio 2022

Additional context

This is a regression since Microsoft.WindowsAppSDK 1.5.241001000, using .NET 7. Reproduction example project uses .NET 8.