Yes, the article goes to some length to mention this but it's worth re-stating, this is all real work, people spent a bunch of effort improving Rust's diagnosti

Yes, the article goes to some length to mention this but it's worth re-stating, this is all real work, people spent a bunch of effort improving Rust's diagnostics, it's not the case that somehow the errors magically get better as the compiler's optimisations improve or something, if you did X and that can't work but the compiler said how about Y, that probably means a person like you had a similar situation and they put work into modifying the diagnostics when you can't do X so that it realises it should suggest Y. My tiny contribution is that when you write say '$' (the dollar symbol as a Unicode char) in a context where you needed a single byte, now rustc will suggest prefixing with a b to make b'$' (the ASCII code of a dollar as a single byte) rather than just telling you that's the wrong type, and yet if you write '€' (the Euro symbol as a Unicode char) it will not suggest b'€' because that's not a thing, the Euro isn't a single byte in ASCII [Yes in some modern 8-bit encodings € exists but those encodings aren't used in Rust, which favours UTF-8, so b'€' wouldn't make sense, in UTF-8 this symbol is 3 bytes]