I didn’t state this directly until now, but I also don’t want IDE code actions as primary facility for code gen. Especially if the generated code would end up mixed with hand written code! That’s just terrible!
Not only I think that @lihaoyi points mostly apply, additionally, how would this work with automated tooling? You don’t use an IDE to do builds in a lot of circumstances; think CI. But code gen is especially useful when run automatically.
The initial proposal looks like a hack, to be honest: “We have some facilities in the compiler and IDE, let’s use them for something nobody else ever did this way”. That’s not a clean design. More the contrary, imho.
The best proposal I’ve seen so far regarding code-gen are the “export macros”.