Today I learned how to write Derive macros and internals of how enums are presented in rustc, by having LLMs generate me code and tweaking it until it worked.

Initial code was generated by Gemini 3 Pro, then it was fed to Copilot agents to produce PRs

But this is like the learning process of a university student. Just like they don't learn why public static void main(String[] args) or whatever it is in Java means until pretty late in the process I still don't know how to define macros, as in, I couldn't write it myself without docs like I can write C++ or Python

But I learned that enum lines are called variants, the assigned value is a discriminant, and that you can even have non-unit variants in your enum type with an integer repr type!