Add release notes for 1.81.0

RELEASES.md

@@ -1,3 +1,117 @@
+Version 1.81.0 (2024-09-05)
+==========================
+
+<a id="1.81.0-Language"></a>
+
+Language
+--------
+
+- [Abort on uncaught panics in `extern "C"` functions.](https://github.com/rust-lang/rust/pull/116088/)
+- [Fix ambiguous cases of multiple `&` in elided self lifetimes.](https://github.com/rust-lang/rust/pull/117967/)
+- [Stabilize `#[expect]` for lints (RFC 2383),](https://github.com/rust-lang/rust/pull/120924/) like `#[allow]` with a warning if the lint is _not_ fulfilled.
+- [Change method resolution to constrain hidden types instead of rejecting method candidates.](https://github.com/rust-lang/rust/pull/123962/)
+- [Bump `elided_lifetimes_in_associated_constant` to deny.](https://github.com/rust-lang/rust/pull/124211/)
+- [`offset_from`: always allow pointers to point to the same address.](https://github.com/rust-lang/rust/pull/124921/)
+- [Allow constraining opaque types during subtyping in the trait system.](https://github.com/rust-lang/rust/pull/125447/)
+- [Allow constraining opaque types during various unsizing casts.](https://github.com/rust-lang/rust/pull/125610/)
+- [Deny keyword lifetimes pre-expansion.](https://github.com/rust-lang/rust/pull/126762/)
+
+<a id="1.81.0-Compiler"></a>
+
+Compiler
+--------
+
+- [Make casts of pointers to trait objects stricter.](https://github.com/rust-lang/rust/pull/120248/)
+- [Check alias args for well-formedness even if they have escaping bound vars.](https://github.com/rust-lang/rust/pull/123737/)
+- [Deprecate no-op codegen option `-Cinline-threshold=...`.](https://github.com/rust-lang/rust/pull/124712/)
+- [Re-implement a type-size based limit.](https://github.com/rust-lang/rust/pull/125507/)
+- [Properly account for alignment in `transmute` size checks.](https://github.com/rust-lang/rust/pull/125740/)
+- [Remove the `box_pointers` lint.](https://github.com/rust-lang/rust/pull/126018/)
+- [Ensure the interpreter checks bool/char for validity when they are used in a cast.](https://github.com/rust-lang/rust/pull/126265/)
+- [Improve coverage instrumentation for functions containing nested items.](https://github.com/rust-lang/rust/pull/127199/)
+- Target changes:
+  - [Add Tier 3 `no_std` Xtensa targets:](https://github.com/rust-lang/rust/pull/125141/) `xtensa-esp32-none-elf`, `xtensa-esp32s2-none-elf`, `xtensa-esp32s3-none-elf`
+  - [Add Tier 3 `std` Xtensa targets:](https://github.com/rust-lang/rust/pull/126380/) `xtensa-esp32-espidf`, `xtensa-esp32s2-espidf`, `xtensa-esp32s3-espidf`
+  - [Add Tier 3 i686 Redox OS target:](https://github.com/rust-lang/rust/pull/126192/) `i686-unknown-redox`
+  - [Promote `arm64ec-pc-windows-msvc` to Tier 2.](https://github.com/rust-lang/rust/pull/126039/)
+  - [Promote `wasm32-wasip2` to Tier 2.](https://github.com/rust-lang/rust/pull/126967/)
+  - [Promote `loongarch64-unknown-linux-musl` to Tier 2 with host tools.](https://github.com/rust-lang/rust/pull/126298/)
+  - [Enable full tools and profiler for LoongArch Linux targets.](https://github.com/rust-lang/rust/pull/127078/)
+  - [Unconditionally warn on usage of `wasm32-wasi`.](https://github.com/rust-lang/rust/pull/126662/) (see compatibility note below)
+  - Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support.
+
+<a id="1.81.0-Libraries"></a>
+
+Libraries
+---------
+
+- [Split core's `PanicInfo` and std's `PanicInfo`.](https://github.com/rust-lang/rust/pull/115974/) (see compatibility note below)
+- [Generalize `{Rc,Arc}::make_mut()` to unsized types.](https://github.com/rust-lang/rust/pull/116113/)
+- [Replace sort implementations with stable `driftsort` and unstable `ipnsort`.](https://github.com/rust-lang/rust/pull/124032/) All `slice::sort*` and `slice::select_nth*` methods are expected to see significant performance improvements. See the [research project](https://github.com/Voultapher/sort-research-rs) for more details.
+- [Document behavior of `create_dir_all` with respect to empty paths.](https://github.com/rust-lang/rust/pull/125112/)
+- [Fix interleaved output in the default panic hook when multiple threads panic simultaneously.](https://github.com/rust-lang/rust/pull/127397/)
+
+<a id="1.81.0-Stabilized-APIs"></a>
+
+Stabilized APIs
+---------------
+
+- [`core::error`](https://doc.rust-lang.org/stable/core/error/index.html)
+- [`hint::assert_unchecked`](https://doc.rust-lang.org/stable/core/hint/fn.assert_unchecked.html)
+- [`fs::exists`](https://doc.rust-lang.org/stable/std/fs/fn.exists.html)
+- [`AtomicBool::fetch_not`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicBool.html#method.fetch_not)
+- [`Duration::abs_diff`](https://doc.rust-lang.org/stable/core/time/struct.Duration.html#method.abs_diff)
+- [`IoSlice::advance`](https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance)
+- [`IoSlice::advance_slices`](https://doc.rust-lang.org/stable/std/io/struct.IoSlice.html#method.advance_slices)
+- [`IoSliceMut::advance`](https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance)
+- [`IoSliceMut::advance_slices`](https://doc.rust-lang.org/stable/std/io/struct.IoSliceMut.html#method.advance_slices)
+- [`PanicHookInfo`](https://doc.rust-lang.org/stable/std/panic/struct.PanicHookInfo.html)
+- [`PanicInfo::message`](https://doc.rust-lang.org/stable/core/panic/struct.PanicInfo.html#method.message)
+- [`PanicMessage`](https://doc.rust-lang.org/stable/core/panic/struct.PanicMessage.html)
+
+These APIs are now stable in const contexts:
+
+- [`char::from_u32_unchecked`](https://doc.rust-lang.org/stable/core/char/fn.from_u32_unchecked.html) (function)
+- [`char::from_u32_unchecked`](https://doc.rust-lang.org/stable/core/primitive.char.html#method.from_u32_unchecked) (method)
+- [`CStr::count_bytes`](https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.count_bytes)
+- [`CStr::from_ptr`](https://doc.rust-lang.org/stable/core/ffi/c_str/struct.CStr.html#method.from_ptr)
+
+<a id="1.81.0-Cargo"></a>
+
+Cargo
+-----
+
+- [Generated `.cargo_vcs_info.json` is always included, even when `--allow-dirty` is passed.](https://github.com/rust-lang/cargo/pull/13960/)
+- [Disallow `package.license-file` and `package.readme` pointing to non-existent files during packaging.](https://github.com/rust-lang/cargo/pull/13921/)
+- [Disallow passing `--release`/`--debug` flag along with the `--profile` flag.](https://github.com/rust-lang/cargo/pull/13971/)
+- [Remove `lib.plugin` key support in `Cargo.toml`. Rust plugin support has been deprecated for four years and was removed in 1.75.0.](https://github.com/rust-lang/cargo/pull/13902/)
+
+<a id="1.81.0-Compatibility-Notes"></a>
+
+Compatibility Notes
+-------------------
+
+* Usage of the `wasm32-wasi` target will now issue a compiler warning and request users switch to the `wasm32-wasip1` target instead. Both targets are the same, `wasm32-wasi` is only being renamed, and this [change to the WASI target](https://blog.rust-lang.org/2024/04/09/updates-to-rusts-wasi-targets.html) is being done to enable removing `wasm32-wasi` in January 2025.
+
+* We have renamed `std::panic::PanicInfo` to `std::panic::PanicHookInfo`. The old name will continue to work as an alias, but will result in a deprecation warning starting in Rust 1.82.0.
+
+  `core::panic::PanicInfo` will remain unchanged, however, as this is now a *different type*.
+
+  The reason is that these types have different roles: `std::panic::PanicHookInfo` is the argument to the [panic hook](https://doc.rust-lang.org/stable/std/panic/fn.set_hook.html) in std context (where panics can have an arbitrary payload), while `core::panic::PanicInfo` is the argument to the [`#[panic_handler]`](https://doc.rust-lang.org/nomicon/panic-handler.html) in no_std context (where panics always carry a formatted *message*). Separating these types allows us to add more useful methods to these types, such as `std::panic::PanicHookInfo::payload_as_str()` and `core::panic::PanicInfo::message()`.
+
+* The new sort implementations may panic if a type's implementation of [`Ord`](https://doc.rust-lang.org/std/cmp/trait.Ord.html) (or the given comparison function) does not implement a [total order](https://en.wikipedia.org/wiki/Total_order) as the trait requires. `Ord`'s supertraits (`PartialOrd`, `Eq`, and `PartialEq`) must also be consistent. The previous implementations would not "notice" any problem, but the new implementations have a good chance of detecting inconsistencies, throwing a panic rather than returning knowingly unsorted data.
+
+<a id="1.81.0-Internal-Changes"></a>
+
+Internal Changes
+----------------
+
+These changes do not affect any public interfaces of Rust, but they represent
+significant improvements to the performance or internals of rustc and related
+tools.
+
+- [Add a Rust-for Linux `auto` CI job to check kernel builds.](https://github.com/rust-lang/rust/pull/125209/)
+
 Version 1.80.0 (2024-07-25)
 ==========================