WPF + Console App Dependency Publishing Bug

Versions

.NET SDK: 5.0.201

Windows: 10 (20H2 / build 19042)

Problem Description

I have a need to create an application that exposes itself as a console application and also a WPF "Windows" application. In some circumstances the console application may show UI from the WPF application. There are also scenarios where the WPF application can be invoked directly (not via the console app).

The problem occurs when trying to run the WPF application directly after publishing the console application (of which the WPF application is a dependency) as a self-contained deployment.

 ---------------------                   -----------------
| Console Application |---depends-on--->| WPF Application |
 ---------------------                   -----------------

Both the console application and WPF application are targeting the Windows specific TFM for .NET 5 (net5.0-windows).

Reproduction Steps

1. Clone this repository
2. Publish the console application for x86 on Windows

PS> dotnet publish .\cli\cli.csproj -r win-x86 -f net5.0-windows

3. Run the console application (works OK)

PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\cli.exe
Hello World!
# A window appears (close the window)
Goodbye World!

4. Run the WPF application (does not run)

PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\wpfapp.exe
# No window appears

One clue to the problem appears if you try to instead publish targeting .NET Framework (for example net472).

PS> dotnet publish .\cli\cli.csproj -r win-x86 -f net472
Microsoft (R) Build Engine version 16.9.0+57a23d249 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
C:\Program Files\dotnet\sdk\5.0.201\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(241,5): error NETSDK1047: Assets file 'C:\Users\<USER>\scratch\wpfconsole\wpfapp\obj\project.assets.json' doesn't have a target for 'net472/win7-x86'. Ensure that restore has run and that you have included 'net472' in the TargetFrameworks for your project. You may also need to include 'win7-x86' in your project's RuntimeIdentifiers. [C:\Users\<USER>\scratch\wpfconsole\wpfapp\wpfapp.csproj]

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BUG 1

The runtime identifier is not being passed through to the child projects on publish. You must update the child apps' project files to specify the RID, or at least include the RID you want to use in a list of RIDs.

Questions:

• Should the chosen publish RID be passed through to child projects on publish?
• Should there be a build warning or error when publishing net5.0*, similar to how net4* behaves?

---

5. Open wpfapp\wpfapp.csproj and add the following <RuntimeIdentifiers/> line:

   <PropertyGroup>
     <OutputType>WinExe</OutputType>
     <TargetFrameworks>net472;net5.0-windows</TargetFrameworks>
+     <RuntimeIdentifiers>win-x86;win-x64</RuntimeIdentifiers>
    <UseWPF>true</UseWPF>
   </PropertyGroup>

6. Retry publishing the console application for net472 (now works OK)

PS> dotnet publish .\cli\cli.csproj -r win-x86 -f net472
PS> .\cli\bin\Debug\net472\win-x86\publish\cli.exe
Hello World!
# A window appears (close the window)
Goodbye World!
PS> .\cli\bin\Debug\net472\win-x86\publish\wpfapp.exe
# A window appears (close the window)

7. Try publishing the console application for net5.0-windows again (works ok!)

PS> dotnet publish .\cli\cli.csproj -r win-x86 -f net5.0-windows
PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\cli.exe
Hello World!
# A window appears (close the window)
Goodbye World!
PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\wpfapp.exe
# A window appears (close the window)

There is also an interesting issue with publishing as a single file (with the -p:PublishSingleFile=true argument).

8. Publish the console application for net5.0-windows as a single file:

PS> dotnet publish .\cli\cli.csproj -r win-x86 -f net5.0-windows -p:PublishSingleFile=true
PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\cli.exe
Hello World!
# A window appears (close the window)
Goodbye World!
PS> .\cli\bin\Debug\net5.0-windows\win-x86\publish\wpfapp.exe
# No window appears

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BUG 2 (?)

It appears the CLR has been bundled in to the console application AppHost (cli.exe, made in to a "SuperHost"), but the WPF application's AppHost (wpfapp.exe) has not (it's not a "SuperHost").

Questions:

• Should each "entry" application in the dependency graph be published as a single file too (multiple copies of the CLR)?
• Include all entry executables in the SuperHost? (... given the executable doesn't actually work, and only serves as a library assembly.)
• Something else (dynamically linking to the other SuperHost)?
• Should a warning be emitted at the very least if this is not supported?

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