NU5131 issues

[zivkan]

NU5131 was added to try to encourage packages that select which assemblies are used by projects to work with both packages.config and PackageReference.

We are currently aware of two issues:

Packages build from MSBuild (no nuspec)

A project that puts a file in ref/<tfm>/ will trigger the warning, therefore asking the package author to create a <references> element in the nuspec. However, the MSBuild pack tasks doesn't provide a way to specify it.

Missing runtime files

See #3830.

[nkolev92]

I think it's perfectly acceptable to create packages which are only compatible with PackageReference (hence using the ref folder).
Even the docs only call out that scenario:
https://docs.microsoft.com/en-us/nuget/reference/errors-and-warnings/nu5131

Right now this is too noisy and defeats the user trust in the warning.
Lots of people will end up disabling them

[ericstj]

Just noticed this. The warning shouldn't force people to use the <references> section if they are creating a package that has parallel ref/lib folders. It should only tell them to do it if the ref folder has different files than lib.

[UmaHarano]

Hi,
I am creating a Nuget package that only supports "PackageReference". So I only have dlls in the "ref" folder. When I run "dotnet pack" I get this warning.

c:\program Files\dotnet\sdk\6.0.101\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(221,5): warning NU5131: References were found in the nuspec, but some reference assemblies were not found in both the nuspec and ref folder. Add the following reference assemblies: [C:\...\Nuget.csproj]
c:\program Files\dotnet\sdk\6.0.101\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(221,5): warning NU5131: - Add MyAssembly.dll to the net5.0-windows reference group in the nuspec [C:\...\Nuget.csproj]

My nuspec file looks like this:

 <dependencies>
      <group targetFramework="net5.0-windows">
      </group>
    </dependencies>
  </metadata>
  <references>
    <group targetFramework="net5.0-windows">
      <reference file="MyAssembly.dll" />
 </group>
  </references>
...

The Nuget is created and I am able to successfully use it. But - Any suggestion as to how I can fix these warnings?
Thank you!