idea by @Victoronz

the unsafe section has a note explaining "how to play the quiz" and the other sections should too

• Borrowck 6 should be borrow checker
• type system 7 should be in the borrow checker category

@Amanieu said that someone suggested also adding an example to unsafe 1 that says (*null,). please give us a GitHub handle to credit Amanieu 😊👉👈

I think it may be useful to more concretely assign difficulty to questions to help users find the ones most interesting to them.
Maybe "easy"/"hard" labels wouldn't be very great, I would think more about levels, where 1 is the easiest and 3 is the hardest or whatever

right now we have to do some (minor) boilerplate every time we add a new quiz entry even though the code and compiler output are already automatically synced from the example to the book. it'd be nice to not have to do any of that somehow and have the explanation for the compiler output be present alongside the example or something?

we can words

In some cases the AST doesn't make clear if a path is a type or a value:

foo::<N>()

Here N could be either. There are some weird fallback rules around this.

//! A link to [`Bar`].

mod foo {
    pub struct Bar;
}

pub use foo::*;
/// The docs
pub use foo::Bar;

does the intra-doc-link have the docs?

answer: it depends if you have --document-private-items

@RalfJung suggested also adding Strong instead of vec, which doesn't have the shadowing methods.

Ideally something like 40 characters width in rustfmt would be perfect for mobile. It would look worse on desktop or print though.

The current rules are really unintuitive, see rust-lang/rust#123590 (comment). It'd make a good question