Rust Devblog 261 🆒 💫

Better error messages for your macro users.

if n % 7 == 0 ...

if n.is_multiple_of(7) ...

Here’s a practical guide covering the key updates from (released February 2025). The focus is on the new proc macro changes , lint stability , cargo script improvements , and standard library additions . Rust Devblog 261 Guide: New Macros, Lints, and Cargo Script 1. Procedural Macros: #[diagnostic] namespace What’s new: You can now emit custom compiler diagnostics from proc macros using the #[diagnostic] attribute. rust devblog 261

fn main() -> Result<()> let re = Regex::new(r"\d+")?; println!("Found numbers: :?", re.find_all("a1 b2 c3")); Ok(()) Better error messages for your macro users

#!/usr/bin/env cargo-script //! ```cargo //! [dependencies] //! regex = "1.10" //! anyhow = "1.0" //! ``` use regex::Regex; use anyhow::Result; Here’s a practical guide covering the key updates

let x = 42u32; assert!(x.is_multiple_of(7)); assert!(!x.is_multiple_of(5)); Avoids division by zero — it’s a panic (same as % ). 5. Cargo: --ignore-rust-version flag What’s new: Build crates even if they require a newer Rust version than your current toolchain.