How can I make a Roslyn Analyzer project a transitive dependency?

Question

I have a library that relies on a source generator to work correctly. In the MyLibrary.csproj, I reference the generator like so.

<ItemGroup>
  <ProjectReference 
        Include="..\MyLibrary.Generators\MyLibrary.Generators.csproj" 
        PrivateAssets="contentfiles;build"
        ReferenceOutputAssembly="false"
        OutputItemType="analyzer"/>
</ItemGroup>

I need this analyzer reference to be transitive, i.e. projects that reference MyLibrary should get the MyLibrary.Generators analyzer transitively.

A simple reference like so does not seem to reference the analyzer, only MyLibrary

<ProjectReference Include="..\MyLibrary\MyLibrary.csproj" />

I want to stress that I am not looking for MyLibrary.Generators to be consumed as a regular assembly reference, but as a Roslyn Analyzer so my source generator can run as intended during compile time.

Boondocks

What is stopping you from adding the project reference manually? Note that if you are looking to ship the binary output from MyLibrary.csproj, you should do so in a nuget package, which can include the generator library. – Wendt

I have an MSBuild SDK set up so presumably consumers of my library will be able to consume the generator as an analyzer reference that way, but I was hoping for a stronger guarantee via transitivity. – Boondocks

Have you been able to find any solution to this? – Guttapercha

No, I haven't, unfortunately. – Boondocks

I don't have an exact answer for you, but I've had some luck using the Microsoft.Build.NoTargets SDK to hand craft nuget packages for project references without causing an assembly reference. I think part of the issue you're having might be related to the ReferenceOutputAssembly="false" which may be interfering with the default pack target dependency generation. – Betti

Did you manage to find a solution for this problem? Currently having the exact same problem and I want to avoid some trickery with nuget packages. – Eppie

I have not been able to find a good solution for this. Currently I'm requiring all consumers of my framework to use a custom MSBuild SDK that references the analyzer project. See here – Boondocks

Answer 1

I have received an answer to this question on GitHub.

It is sufficient for the library project to have the following reference to the generator project:

  <ItemGroup>
    <!-- Package the generator in the analyzer directory of the nuget package -->
    <None Remove="$(OutputPath)/$(AssemblyName).Generator.dll" />
    <None Include="$(OutputPath)/$(AssemblyName).Generator.dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
  </ItemGroup>

(I am not sure if the Remove line does anything. It might be unnecessary.)

When the library is consumed as a NuGet package, the generator is automatically included as an analyzer, i.e. the analyzer reference is transitive.

However, when the library is consumed through a project reference (such as in the library's own unit test project), we need the following:

  <ItemGroup>
    <ProjectReference Include="..\MyLibrary\MyLibrary.csproj" />
    <ProjectReference Include="..\MyLibrary.Generator\MyLibrary.Generator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
  </ItemGroup>

The examples in the original post all handle project references. From what I have gathered, a transitive project reference to an analyzer seems impossible, unfortunately.

Oringas

Drawback: If the Generator project depends on other packages, they are not referenced in the resulting package. – Cubital