Chapter 5. Changes in Rust 1.62.1 Toolset

Rust Toolset has been updated from version 1.58.0 to 1.62.1 on RHEL 7, RHEL 8, and RHEL 9.

Notable changes include:

Destructuring assignment allows patterns to assign to existing variables in the left-hand side of an assignment. For example, a tuple assignment can swap to variables: (a, b) = (b, a);
Inline assembly is now supported on 64-bit x86 and 64-bit ARM using the core::arch::asm! macro. See more details in the "Inline assembly" chapter of the reference, "/usr/share/doc/rust/html/reference/inline-assembly.html". (online at https://doc.rust-lang.org/reference/inline-assembly.html)
Enums can now derive the Default trait with an explicitly annotated #[default] variant.
Mutex, CondVar, and RwLock now use a custom futex-based implementation rather than pthreads, with new optimizations made possible by Rust language guarantees.
Rust now supports custom exit codes from main, including user-defined types that implement the newly-stabilized Termination trait.
Cargo supports more control over dependency features. The "dep:" prefix can refer to an optional dependency without exposing that as a feature, and a "?" only enables a dependency feature if that dependency is enabled elsewhere, like "package-name?/feature-name".
Cargo has a new cargo add subcommand for adding dependencies to Cargo.toml.

For detailed information regarding the updates, see the series of upstream release announcements: