We appreciate your contribution, but a small thing first: would you mind fixing your formatting? Your spacing is messed up and it makes your sentences look awkward. Please add exactly one space after each punctuation symbol (like dot, comma or triple dots).
I definitely do not recommend working on Rust compiler itself without getting familiar with the language. Personally, I think you should do some personal projects in Rust then contribute to a crate, not the compiler itself (the compiler is very complicated).
Judging from the conversation on the issue, I do not think that continuously trying to understand the corresponding code will help you get better on Rust. Please get used to reading code by other means, then work on the compiler. Anyway, I think you could read the documentation instead of relying on the code comments. (It’s often faster and more accurate than asking, too.) The steps to work on compiler development is described in the first few chapters, and detailed explanation about MIR const evaluator is in section 24.
