The Rust team is happy to announce the latest version of Rust, 1.10. Rust is a systems programming language focused on safety, speed, and concurrency.

As always, you can install Rust 1.10 from the appropriate page on our website, and check out the detailed release notes for 1.10 on GitHub. 1276 patches were landed in this release.

What's in 1.10 stable

Rust 1.10 contains one of the most-requested features in Rust: through the -C panic=abort flag or a setting in your Cargo.toml , when a panic! happens, it will abort rather than unwind. Why would you want to do this? Remember that panics are for unexpected problems, and for many applications, aborting is a reasonable choice. With an abort, less code gets generated, meaning that binary sizes are a bit smaller, and compilation time is ever-so-slightly faster. Some very rough numbers are 10% smaller binaries, and 10% faster compilation time. This feature was defined in RFC 1513.

The second big feature in 1.10 is a new crate type: cdylib . The existing dylib dynamic library format will now be used solely for writing a dynamic library to be used within a Rust project, while cdylib s will be used when compiling Rust code as a dynamic library to be embedded in another language. With the 1.10 release, cdylib s are supported by the compiler, but not yet in Cargo. This format was defined in RFC 1510.

In addition, a number of performance improvements landed in the compiler, and so did a number of usability improvements across the documentation, rustdoc itself, and various error messages.

Finally, there's a large change to the way that we develop Rust that won't impact Rust users directly, but will help those distributing Rust significantly. Rust is implemented in Rust, which means that to build a copy of Rust, you need a copy of Rust. This is commonly referred to as 'bootstrapping'. Historically, we would do this by "snapshotting" a specific version of the compiler, and always bootstrapping from that; the snapshot would periodically be updated, as needed. Furthermore, since the Rust compiler uses unstable Rust features, in order to build a copy of the stable compiler, you would need a specific nightly version of the Rust compiler. This has served us well for years, but we've outgrown it now. The main drawback to this approach is that it requires downloading a snapshot binary, which is not ideal for an important constituency: Linux distributions. In particular, distros generally want to be able to build the latest version of Rust using only previously-packaged versions that they have produced, rather than via untrusted binaries. As such, we have modified our build system so that Rust 1.10 builds with Rust 1.9. In the future, this pattern will continue; Rust 1.11 will be built with Rust 1.10. Furthermore, you can use the stable compiler to build the compiler. This simplifies everything around bootstrapping, and helps distribution maintainers significantly, as they no longer need two packages. You can find more details about this change in its pull request.

See the detailed release notes for more.

Library stabilizations

Roughly 70 APIs were made stable in this release. They break down into these rough groups:

In addition, Default was implemented for &CStr , CString , UnsafeCell , fmt::Error , Condvar , Mutex , and RwLock .

Finally, on Linux, if HashMaps can't be initialized with getrandom they will fall back to /dev/urandom temporarily to avoid blocking during early boot.

See the detailed release notes for more.

Cargo features

Cargo has received a number of small improvements in this release.

See the detailed release notes for more.

Contributors to 1.10

We had 139 individuals contribute to 1.10. Thank you so much!