Refer to Rust's [platform support page][platform-support-doc]
for more information on Rust's tiered platform support.
Libraries
---------
- [Implement `PartialEq` for `ExitCode`.](https://github.com/rust-lang/rust/pull/127633)
- [Document that `catch_unwind` can deal with foreign exceptions without UB, although the exact behavior is unspecified.](https://github.com/rust-lang/rust/pull/128321)
- [Implement `Default` for `HashMap`/`HashSet` iterators that don't already have it.](https://github.com/rust-lang/rust/pull/128711)
- [Bump Unicode to version 16.0.0.](https://github.com/rust-lang/rust/pull/130183)
- [Change documentation of `ptr::add`/`sub` to not claim equivalence with `offset`.](https://github.com/rust-lang/rust/pull/130229)
- [Introduced a new `CARGO_MANIFEST_PATH` environment variable, similar to `CARGO_MANIFEST_DIR` but pointing directly to the manifest file.](https://github.com/rust-lang/cargo/pull/14404/)
- [Added `package.autolib` to the manifest, allowing `[lib]` auto-discovery to be disabled.](https://github.com/rust-lang/cargo/pull/14591/)
- [Declare support level for each crate in Cargo's Charter / crate docs.](https://github.com/rust-lang/cargo/pull/14600/)
- [Declare new Intentional Artifacts as 'small' changes.](https://github.com/rust-lang/cargo/pull/14599/)
Rustdoc
-------
- [The sidebar / hamburger menu table of contents now includes the `# headers` from the main item's doc comment](https://github.com/rust-lang/rust/pull/120736). This is similar to a third-party feature provided by the rustdoc-search-enhancements browser extension.
Compatibility Notes
-------------------
- [Warn against function pointers using unsupported ABI strings.](https://github.com/rust-lang/rust/pull/128784)
- [Check well-formedness of the source type's signature in fn pointer casts.](https://github.com/rust-lang/rust/pull/129021) This partly closes a soundness hole that comes when casting a function item to function pointer
- [Use equality instead of subtyping when resolving type dependent paths.](https://github.com/rust-lang/rust/pull/129073)
- Linking on macOS now correctly includes Rust's default deployment target. Due to a linker bug, you might have to pass `MACOSX_DEPLOYMENT_TARGET` or fix your `#[link]` attributes to point to the correct frameworks. See <https://github.com/rust-lang/rust/pull/129369>.
- [Rust will now correctly raise an error for `repr(Rust)` written on non-`struct`/`enum`/`union` items, since it previous did not have any effect.](https://github.com/rust-lang/rust/pull/129422)
- The future incompatibility lint `deprecated_cfg_attr_crate_type_name` [has been made into a hard error](https://github.com/rust-lang/rust/pull/129670). It was used to deny usage of `#![crate_type]` and `#![crate_name]` attributes in `#![cfg_attr]`, which required a hack in the compiler to be able to change the used crate type and crate name after cfg expansion.
Users can use `--crate-type` instead of `#![cfg_attr(..., crate_type = "...")]` and `--crate-name` instead of `#![cfg_attr(..., crate_name = "...")]` when running `rustc`/`cargo rustc` on the command line.
Use of those two attributes outside of `#![cfg_attr]` continue to be fully supported.
- Until now, paths into the sysroot were always prefixed with `/rustc/$hash` in diagnostics, codegen, backtrace, e.g.
```
thread 'main' panicked at 'hello world', map-panic.rs:2:50
stack backtrace:
0: std::panicking::begin_panic
at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/std/src/panicking.rs:616:12
1: map_panic::main::{{closure}}
at ./map-panic.rs:2:50
2: core::option::Option<T>::map
at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/option.rs:929:29
3: map_panic::main
at ./map-panic.rs:2:30
4: core::ops::function::FnOnce::call_once
at /rustc/a55dd71d5fb0ec5a6a3a9e8c27b2127ba491ce52/library/core/src/ops/function.rs:248:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
> We want to change this behaviour such that, when `rust-src` source files can be discovered, the virtual path is discarded and therefore the local path will be embedded, unless there is a `--remap-path-prefix` that causes this local path to be remapped in the usual way.
[#129687](https://github.com/rust-lang/rust/pull/129687) implements this behaviour, when `rust-src` is present at compile time, `rustc` replaces `/rustc/$hash` with a real path into the local `rust-src` component with best effort.
To sanitize this, users must explicitly supply `--remap-path-prefix=<path to rust-src>=foo` or not have the `rust-src` component installed.
- The allow-by-default `missing_docs` lint used to disable itself when invoked through `rustc --test`/`cargo test`, resulting in `#[expect(missing_docs)]` emitting false positives due to the expectation being wrongly unfulfilled. This behavior [has now been removed](https://github.com/rust-lang/rust/pull/130025), which allows `#[expect(missing_docs)]` to be fulfilled in all scenarios, but will also report new `missing_docs` diagnostics for publicly reachable `#[cfg(test)]` items, [integration test](https://doc.rust-lang.org/cargo/reference/cargo-targets.html#integration-tests) crate-level documentation, and publicly reachable items in integration tests.
- [The `armv8r-none-eabihf` target now uses the Armv8-R required set of floating-point features.](https://github.com/rust-lang/rust/pull/130295)
- [Fix a soundness bug where rustc wouldn't detect unconstrained higher-ranked lifetimes in a `dyn Trait`'s associated types that occur due to supertraits.](https://github.com/rust-lang/rust/pull/130367)
- [Update the minimum external LLVM version to 18.](https://github.com/rust-lang/rust/pull/130487)
- [Remove `aarch64-fuchsia` and `x86_64-fuchsia` target aliases in favor of `aarch64-unknown-fuchsia` and `x86_64-unknown-fuchsia` respectively.](https://github.com/rust-lang/rust/pull/130657)
- [The ABI-level exception class of a Rust panic is now encoded with native-endian bytes, so it is legible in hex dumps.](https://github.com/rust-lang/rust/pull/130897)
- [Visual Studio 2013 is no longer supported for MSVC targets.](https://github.com/rust-lang/rust/pull/131070)
- [The sysroot no longer contains the `std` dynamic library in its top-level `lib/` dir.](https://github.com/rust-lang/rust/pull/131188)
