Rust 1.69: What's New, Release History & Support Lifecycle

What Is New in Rust 1.69

How does Cargo now suggest automatic fixes for warnings?

Cargo now prints a suggestion to run cargo fix or cargo clippy --fix when it encounters warnings that can be fixed automatically.

This helps developers address simple issues without leaving the command line, keeping the codebase clean and reducing the noise of repetitive warnings.

warning: unused import: `std::hash::Hash`
 --> src/main.rs:1:5
  |
1 | use std::hash::Hash;
  |     ^^^^^^^^^^^^^^^
  = note: `#[warn(unused_imports)]` on by default

warning: `foo` (bin "foo") generated 1 warning (run `cargo fix --bin "foo"` to apply 1 suggestion)

If you want to apply fixes across an entire workspace, a plain cargo fix is sufficient; the detailed invocation is only needed for fine-grained control.

Why are build scripts compiled without debug information by default?

Build scripts are compiled without debug symbols in order to speed up compilation and reduce the size of the intermediate artifacts.

This change has no visible effect on successful builds, but backtraces from failing build scripts will contain less detail.

When you need full backtraces, re-enable debug info by adding the following to Cargo.toml:

[profile.dev.build-override]
debug = true
[profile.release.build-override]
debug = true

Which APIs became const-stable in Rust 1.69?

Rust 1.69 promotes a handful of standard-library items to const-stable, allowing them to be used inside const fn and other constant evaluation contexts.

This expands the toolbox for compile-time computation without requiring nightly features, making const-generic code easier to write and maintain.