Announcing Rust 1.97.0

The Rust team is happy to announce a new version of Rust, 1.97.0.

Rust is a programming language empowering everyone to build reliable and efficient software. If you have a previous version of Rust installed via rustup, you can get 1.97.0 with: $ rustup update stable If you don't have it already, you can get rustup from the appropriate page on our website, and check out the detailed release notes for 1.97.0.

If you'd like to help us out by testing future releases, you might consider updating locally to use the beta channel (rustup default beta) or the nightly channel (rustup default nightly). Please report any bugs you might come across!

What's in 1.97.0 stable Symbol mangling v0 enabled by default When Rust is compiled into object files and binaries, each item (functions, statics, etc) must have a globally unique "symbol" identifying it. To avoid conflicts when linking together different Rust programs, Rust mangles the original name of items to include additional context such as the module path, defining crate, generics, and more.

Historically, this mangling was based on the Itanium ABI, also (sometimes) used by C++.

The new mangling scheme resolves a number of drawbacks from the previous one: Generic parameter instantiations preserve their values, rather than being tracked solely behind a hash Inconsistencies: not all parts used the Itanium ABI, meaning that custom demangling was still necessary Since Rust 1.59, the compiler has supported opting into a Rust-specific mangling scheme via -Csymbol-mangling-version=v0.

Since November 2025, this scheme has been enabled by default on nightly, and 1.97 is now enabling it on stable Rust. The legacy mangling scheme can only be enabled on nightly, and the current plan is to fully remove it. See the previous blog post for more details.

Cargo support for denying warnings It's common practice to deny warnings in CI. Historically, doing so is typically done through RUSTFLAGS=-Dwarnings. With Rust 1.97, Cargo controls how warnings interact with build success: either silencing them (via allow level), rendering without failing (default, warn), or denying them (via deny).

As a result of Cargo configuration determining the behavior, using this feature doesn't invalidate the underlying build cache, meaning that it's easy to temporarily opt-in. For example, if warnings are adding unwanted noise while working through fixing errors after a refactor, you can run CARGO_BUILD_WARNINGS=allow cargo check, temporarily silencing them.

In CI, jobs can instead set CARGO_BUILD_WARNINGS=deny to deny warnings. This can be combined with --keep-going to collect all errors and warnings rather than stopping on the first failing package. See the documentation for more details.

Linker output no longer hidden by default rustc invokes a linker on behalf of users. Historically, rustc has silenced linker output by default if the link completes successfully. This can mask real problems, though, so in Rust 1.97 we are enabling linker messages by default.

These are emitted as a warning lint, for example: warning: linker stderr: ignoring deprecated linker optimization setting '1' | = note: `#[warn(linker_messages)]` on by default Common linker messages that have been diagnosed as false positives or intentional behavior are filtered out by rustc. Several defects have already been fixed as a result of no longer hiding this output on nightly.

Note that currently, linker_messages is a special lint that is not affected by the warnings lint group. This is intentional as rustc generally doesn't control linker output as precisely, and it's not uncommon for output to only appear on some platforms. If you are seeing what you think is a false positive output from the linker, please file an issue.

To silence the warning in the mean time, you can configure the lint level to allow.

This can be done through Cargo.toml by adding a lints section like this: [lints.rust] linker_messages = "allow" Stabilized APIs Default for RepeatN Copy for ffi::FromBytesUntilNulError Send for std::fs::File on UEFI <{integer}>::isolate_highest_one <{integer}>::isolate_lowest_one <{integer}>::highest_one <{integer}>::lowest_one <{uN}>::bit_width NonZero<{integer}>::isolate_highest_one NonZero<{integer}>::isolate_lowest_one NonZero<{integer}>::highest_one NonZero<{integer}>::lowest_one NonZero<{uN}>::bit_width These previously stable APIs are now stable in const contexts: char::is_control Other changes Check out everything that changed in Rust, Cargo, and Clippy.

Contributors to 1.97.0 Many people came together to create Rust 1.97.0. We couldn't have done it without all of you. Thanks!