One of the new features in .NET 5 that triggered my curiosity where source generators. I did some investigation on how to use them and want to share the lessons I learned along the way.
Yesterday I wrote my first generator. Unfortunately nothing happened and no new code was generated. I tried to attach the debugger but when I did a rebuild still nothing happened. It seems that the code itself was never called.
It took me some time to figure out why it didn’t work; it turns out that you have to add your source generator to a separate assembly(which makes sense). In my first try I just added the source generator logic to the same project as the other code but this doesn’t work.
How to package a source generator?
To get source generators up and running, you need to create a separate project add the source generator logic there.
So create a new .NET Standard project and add a reference to the following package:
Generators can be packaged using the same method as an Analyzer would. Therefore the generator should be placed in the analyzers\dotnet\cs folder of the package for it to be automatically added to the users project on install. To enable this we need to add the following to your project file:
Now we can add our source generators here.
There is one last step you also need to take into account. If you just create a reference to your SourceGenerator project it will not work. You have to change the project reference and include `OutputItemType="Analyzer" ReferenceOutputAssembly="false"`:
Now the source generator is finally invoked when I build my code.