Out with Rust 1.85 and the 2024 Edition is a significant update to the official Rust book: with me as an author and a new chapter on async Rust!

Empowering everyone to build reliable and efficient software.

This stabilizes the 2024 edition for Rust 1.85, scheduled to be released on February 20, 2025. 🎉 cc tracking issue: #117258 There is a fair amount of follow-up work after this that I am working on ...

doc.rust-lang.org ### Disallow references to static mut - The Rust Edition Guide > In situations where no locally-reasoned abstraction is possible and you are therefore compelled still to reason globally about accesses to your `static` variable, you must now use raw pointers such as can be obtained via the `&raw const` or `&raw mut` operators. By first obtaining a raw pointer rather than directly taking a reference, (the safety requirements of) accesses through that pointer will be more familiar to `unsafe` developers and can be deferred until/limited to smaller regions of code. So you could... unsafe { REQUEST_COUNTER += 1; println!("Requests processed (unsafe): {}", *&raw const REQUEST_COUNTER); }

OK, it is discussed in the edition guide in Disallow references to static mut - The Rust Edition Guide But I am still unsure how to modify the text. People might wonder why static mut was allowed for more than ten years, and no is forbidden. But well, I think a lot of alternatives are listed in the book, so perhaps I should just say that use of static mut is not any longer allowed.

I'm on mobile now but as a passing thought: reading the (small) value into a temp and printing the temp could avoid creating a reference to the static place, unlike my snippet above.

StefanSalewski: > People might wonder why static mut was allowed for more than ten years, and no is forbidden. The fact that many of the alternatives are only recently existing is why. Here's a relevant issue with tons of conversation. In terms of your book, I would say note especially the first dozen or so posts that hash out why `UnsafeCell` is safer than `static mut` (reentrancy, mere existence of aliasing references).

A few books have still examples for static mut variables. So I added one myself, telling that one should avoid them. But I think in last year the example was compiling, but now with Rust 2024 it fails in the playground, and I am unsure how I should modify the example and the text. The easiest way would be to just say that use of static mut is not longer permitted. Is that good enough? I discovered that a #!allow(static_mut_refs)] makes it compile in the playground. I will try to give a link to the playground example code, it is from section [Variables and mutability - Rust for C-Programmers of the book. play.rust-lang.org ### Rust Playground A browser interface to the Rust compiler to experiment with the language

Rust2024 will be released soon, should it get stricter to prevent some "safe" bugs? E.g, it currently allows to get a pointer without unsafe, only dereferencing a pointer needs unsafe.