Rust 1.92: What's New, Release History & Support Lifecycle

What Is New in Rust 1.92

What does the new deny-by-default never type lint mean for my crates?

The new deny-by-default lints never_type_fallback_flowing_into_unsafe and dependency_on_unit_never_type_fallback will turn into hard errors when they are triggered.

• They fire only when the affected crate is compiled directly, not when it appears only as a dependency.
• Cargo will emit a warning for dependent crates, giving you a heads-up before the error appears.
• Typical fix: replace unit-type fallbacks with proper never-type handling or add #[allow(never_type_fallback_flowing_into_unsafe)] if you need a temporary workaround.

In practice, about 500 crates on crates.io are expected to hit these lints, so plan a migration window before upgrading a large codebase.

How does Rust 1.92 treat Result<(), Infallible> in the unused_must_use lint?

Rust 1.92 no longer warns when you ignore a Result<(), Infallible> or any Result<(), UninhabitedType>.

use core::convert::Infallible;
fn never_fails() -> Result<(), Infallible> {
    Ok(())
}
fn main() {
    never_fails(); // No unused_must_use warning
}

This matters if you have generic traits with an associated error type that can be Infallible; the lint now respects the fact that the error branch can never be constructed.

Will backtraces still work when I compile with -Cpanic=abort on Linux?

Yes, Rust 1.92 emits unwind tables by default even when -Cpanic=abort is set on Linux.

• Backtraces will be available without the need for the -Cforce-unwind-tables=yes flag.
• If you deliberately want to omit unwind tables, pass -Cforce-unwind-tables=no.

This improvement restores the behavior that existed before Rust 1.23 and simplifies debugging in low-overhead abort-panic configurations.

What new const-stabilized APIs are available in Rust 1.92?

Several previously stable APIs have been promoted to const-stable, allowing them to be used in compile-time contexts.

• Functions and methods that were only usable at runtime can now appear in const fn bodies, enabling more powerful compile-time computation.
• Typical use-case: building static lookup tables or performing validation in const contexts without resorting to build scripts.

Check the detailed release notes for the exact list of APIs that gained const stability.