Performance with Profiling Part 3: Profiling and Production

Source Generators are a new C# feature currently in preview that runs during compilation and can inspect your program to produce additional files that are compiled together with the rest of your code. Roslyn PMs Chris Sienkiewicz and Phillip Carter show how this works and how you can benefit from it in Visual Studio.
For more information on this, check out the Visual Studio blog post here.
This would have been useful for a project I am working on with auto mapping between database object and service object with the same property on both sides.
'Way back in ancient times there actually used to be a feature called 'macros' which was essentially a VBS back-end that you could use to write programs to generate code that would slap code into your code depending on whatever you wanted them to depend on. I used to have tons of VBS macros in there. Then Microsoft ripped out that VBS macro facility entirely and I've since been stuck doing it the hard way - by hand. Having a similar facility built back into the system should be highly entertaining. Those macros used to save me a ton of time. Having the ability to easily share them with the team will also be a big bonus. I'm sure others will have ideas, too.
Q: Is it possible to add a real file to the solution?
I mean, I know it's autogenerated, but I want to make a changes to the auto generated class!