NuGet restore for .NET 6 Android project seems to ignore fallback frameworks

[leonluc-dev]

Prerequisites

• I have written a descriptive issue title
• I have searched issues to ensure it has not already been reported

Cake runner

Cake .NET Tool

Cake version

1.3.0

Operating system

Windows

Operating system architecture

64-Bit

CI Server

No response

What are you seeing?

I have .NET 6 project targeting net6.0-android I want to build using cake. This works fine using a simple command line build like dotnet build MyProject.csproj, however when I build the same project in cake using DotNetCoreBuild I get the following error during the restore phase:

NU1202: Package Xamarin.Google.Guava.ListenableFuture 1.0.0.2 is not compatible with net6.0-android31.0 (.NETCoreApp,Version=v6.0) / android-arm64. Package Xamarin.Google.Guava.ListenableFuture 1.0.0.2 supports: monoandroid50 (MonoAndroid,Version=v5.0)

What is expected?

The net6.0-android target supports monodroid packages and NuGet is supposed restore them appropriately.

Steps to Reproduce

1. Create a .NET 6 project with target framework net6.0-android
2. Add a monodroid based NuGet package to it (for example Xamarin.Google.Guava.ListenableFuture 1.0.0.2).
   No other code should be required to reproduce the issue
3. Try to build it using the DotNetCoreBuild method in cake
4. The error mentioned above should occur

Output log

No response

[augustoproiete]

Under the hood, Cake is calling dotnet build as well, so there shouldn't be any difference between you calling dotnet build directly or Cake calling it via DotNetCoreBuild.

If you run Cake with the argument --settings_showprocesscommandline=true you can see exactly the dotnet build command-line being executed, and that might give you some clues as to what's different.

e.g.

dotnet cake --settings_showprocesscommandline=true

Otherwise, if you can put together a reproducible example, that would help troubleshoot this.

[leonluc-dev]

Thanks for the parameter hint. With that I was able to notice an oversight in the script that caused ./tools/nuget.exe to be run instead of dotnet restore (an imported script called NuGetRestore instead of DotNetCoreRestore). Since the Nuget binary in the tools folder (v5.11, added by the bootstrap) doesn't support .NET 6.0 projects yet it makes sense it would fail.