| 
 | 1 | +Version 1.86.0 (2025-04-03)  | 
 | 2 | +==========================  | 
 | 3 | + | 
 | 4 | +<a id="1.86.0-Language"></a>  | 
 | 5 | + | 
 | 6 | +Language  | 
 | 7 | +--------  | 
 | 8 | +- [Stabilize upcasting trait objects to supertraits.](https://github.com/rust-lang/rust/pull/134367)  | 
 | 9 | +- [Allow safe functions to be marked with the `#[target_feature]` attribute.](https://github.com/rust-lang/rust/pull/134090)  | 
 | 10 | +- [The `missing_abi` lint now warns-by-default.](https://github.com/rust-lang/rust/pull/132397)  | 
 | 11 | +- Rust now lints about double negations, to catch cases that might have intended to be a prefix decrement operator (`--x`) as written in other languages. This was previously a clippy lint, `clippy::double_neg`, and is [now available directly in Rust as `double_negations`.](https://github.com/rust-lang/rust/pull/126604)  | 
 | 12 | +- [More pointers are now detected as definitely not-null based on their alignment in const eval.](https://github.com/rust-lang/rust/pull/133700)  | 
 | 13 | +- [Empty `repr()` attribute applied to invalid items are now correctly rejected.](https://github.com/rust-lang/rust/pull/133925)  | 
 | 14 | +- [Inner attributes `#![test]` and `#![rustfmt::skip]` are no longer accepted in more places than intended.](https://github.com/rust-lang/rust/pull/134276)  | 
 | 15 | + | 
 | 16 | +<a id="1.86.0-Compiler"></a>  | 
 | 17 | + | 
 | 18 | +Compiler  | 
 | 19 | +--------  | 
 | 20 | +- [Debug-assert that raw pointers are non-null on access.](https://github.com/rust-lang/rust/pull/134424)  | 
 | 21 | +- [Change `-O` to mean `-C opt-level=3` instead of `-C opt-level=2` to match Cargo's defaults.](https://github.com/rust-lang/rust/pull/135439)  | 
 | 22 | +- [Fix emission of `overflowing_literals` under certain macro environments.](https://github.com/rust-lang/rust/pull/136393)  | 
 | 23 | + | 
 | 24 | +<a id="1.86.0-Platform-Support"></a>  | 
 | 25 | + | 
 | 26 | +Platform Support  | 
 | 27 | +----------------  | 
 | 28 | +- [Replace `i686-unknown-redox` target with `i586-unknown-redox`.](https://github.com/rust-lang/rust/pull/136698)  | 
 | 29 | +- [Increase baseline CPU of `i686-unknown-hurd-gnu` to Pentium 4.](https://github.com/rust-lang/rust/pull/136700)  | 
 | 30 | +- New tier 3 targets:  | 
 | 31 | +  - [`{aarch64-unknown,x86_64-pc}-nto-qnx710_iosock`](https://github.com/rust-lang/rust/pull/133631).  | 
 | 32 | +    For supporting Neutrino QNX 7.1 with `io-socket` network stack.  | 
 | 33 | +  - [`{aarch64-unknown,x86_64-pc}-nto-qnx800`](https://github.com/rust-lang/rust/pull/133631).  | 
 | 34 | +    For supporting Neutrino QNX 8.0 (`no_std`-only).  | 
 | 35 | +  - [`{x86_64,i686}-win7-windows-gnu`](https://github.com/rust-lang/rust/pull/134609).  | 
 | 36 | +    Intended for backwards compatibility with Windows 7. `{x86_64,i686}-win7-windows-msvc` are the Windows MSVC counterparts that already exist as Tier 3 targets.  | 
 | 37 | +  - [`amdgcn-amd-amdhsa`](https://github.com/rust-lang/rust/pull/134740).  | 
 | 38 | +  - [`x86_64-pc-cygwin`](https://github.com/rust-lang/rust/pull/134999).  | 
 | 39 | +  - [`{mips,mipsel}-mti-none-elf`](https://github.com/rust-lang/rust/pull/135074).  | 
 | 40 | +    Initial bare-metal support.  | 
 | 41 | +  - [`m68k-unknown-none-elf`](https://github.com/rust-lang/rust/pull/135085).  | 
 | 42 | +  - [`armv7a-nuttx-{eabi,eabihf}`, `aarch64-unknown-nuttx`, and `thumbv7a-nuttx-{eabi,eabihf}`](https://github.com/rust-lang/rust/pull/135757).  | 
 | 43 | + | 
 | 44 | +Refer to Rust's [platform support page][platform-support-doc]  | 
 | 45 | +for more information on Rust's tiered platform support.  | 
 | 46 | + | 
 | 47 | +<a id="1.86.0-Libraries"></a>  | 
 | 48 | + | 
 | 49 | +Libraries  | 
 | 50 | +---------  | 
 | 51 | +- The type of `FromBytesWithNulError` in `CStr::from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, FromBytesWithNulError>` was [changed from an opaque struct to an enum](https://github.com/rust-lang/rust/pull/134143), allowing users to examine why the conversion failed.  | 
 | 52 | +- [Remove `RustcDecodable` and `RustcEncodable`.](https://github.com/rust-lang/rust/pull/134272)  | 
 | 53 | +- [Deprecate libtest's `--logfile` option.](https://github.com/rust-lang/rust/pull/134283)  | 
 | 54 | +- [On recent versions of Windows, `std::fs::remove_file` will now remove read-only files.](https://github.com/rust-lang/rust/pull/134679)  | 
 | 55 | + | 
 | 56 | +<a id="1.86.0-Stabilized-APIs"></a>  | 
 | 57 | + | 
 | 58 | +Stabilized APIs  | 
 | 59 | +---------------  | 
 | 60 | + | 
 | 61 | +- [`{float}::next_down`](https://doc.rust-lang.org/stable/std/primitive.f64.html#method.next_down)  | 
 | 62 | +- [`{float}::next_up`](https://doc.rust-lang.org/stable/std/primitive.f64.html#method.next_up)  | 
 | 63 | +- [`<[_]>::get_disjoint_mut`](https://doc.rust-lang.org/stable/std/primitive.slice.html#method.get_disjoint_mut)  | 
 | 64 | +- [`<[_]>::get_disjoint_unchecked_mut`](https://doc.rust-lang.org/stable/std/primitive.slice.html#method.get_disjoint_unchecked_mut)  | 
 | 65 | +- [`slice::GetDisjointMutError`](https://doc.rust-lang.org/stable/std/slice/enum.GetDisjointMutError.html)  | 
 | 66 | +- [`HashMap::get_disjoint_mut`](https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.get_disjoint_mut)  | 
 | 67 | +- [`HashMap::get_disjoint_unchecked_mut`](https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.get_disjoint_unchecked_mut)  | 
 | 68 | +- [`NonZero::count_ones`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.count_ones)  | 
 | 69 | +- [`Vec::pop_if`](https://doc.rust-lang.org/std/vec/struct.Vec.html#method.pop_if)  | 
 | 70 | +- [`sync::Once::wait`](https://doc.rust-lang.org/stable/std/sync/struct.Once.html#method.wait)  | 
 | 71 | +- [`sync::Once::wait_force`](https://doc.rust-lang.org/stable/std/sync/struct.Once.html#method.wait_force)  | 
 | 72 | +- [`sync::OnceLock::wait`](https://doc.rust-lang.org/stable/std/sync/struct.OnceLock.html#method.wait)  | 
 | 73 | + | 
 | 74 | +These APIs are now stable in const contexts:  | 
 | 75 | + | 
 | 76 | +- [`hint::black_box`](https://doc.rust-lang.org/stable/std/hint/fn.black_box.html)  | 
 | 77 | +- [`io::Cursor::get_mut`](https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.get_mut)  | 
 | 78 | +- [`io::Cursor::set_position`](https://doc.rust-lang.org/stable/std/io/struct.Cursor.html#method.set_position)  | 
 | 79 | +- [`str::is_char_boundary`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.is_char_boundary)  | 
 | 80 | +- [`str::split_at`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at)  | 
 | 81 | +- [`str::split_at_checked`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_checked)  | 
 | 82 | +- [`str::split_at_mut`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_mut)  | 
 | 83 | +- [`str::split_at_mut_checked`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.split_at_mut_checked)  | 
 | 84 | + | 
 | 85 | +<a id="1.86.0-Cargo"></a>  | 
 | 86 | + | 
 | 87 | +Cargo  | 
 | 88 | +-----  | 
 | 89 | +- [When merging, replace rather than combine configuration keys that refer to a program path and its arguments.](https://github.com/rust-lang/cargo/pull/15066/)  | 
 | 90 | +- [Error if both `--package` and `--workspace` are passed but the requested package is missing.](https://github.com/rust-lang/cargo/pull/15071/) This was previously silently ignored, which was considered a bug since missing packages should be reported.  | 
 | 91 | +- [Deprecate the token argument in `cargo login` to avoid shell history leaks.](https://github.com/rust-lang/cargo/pull/15057/)  | 
 | 92 | +- [Simplify the implementation of `SourceID` comparisons.](https://github.com/rust-lang/cargo/pull/14980/) This may potentially change behavior if the canonicalized URL compares differently in alternative registries.  | 
 | 93 | + | 
 | 94 | +<a id="1.86.0-Rustdoc"></a>  | 
 | 95 | + | 
 | 96 | +Rustdoc  | 
 | 97 | +-----  | 
 | 98 | +- [Add a sans-serif font setting.](https://github.com/rust-lang/rust/pull/133636)  | 
 | 99 | + | 
 | 100 | +<a id="1.86.0-Compatibility-Notes"></a>  | 
 | 101 | + | 
 | 102 | +Compatibility Notes  | 
 | 103 | +-------------------  | 
 | 104 | +- [The `wasm_c_abi` future compatibility warning is now a hard error.](https://github.com/rust-lang/rust/pull/133951)  | 
 | 105 | +  Users of `wasm-bindgen` should upgrade to at least version 0.2.89, otherwise compilation will fail.  | 
 | 106 | +- [Remove long-deprecated no-op attributes `#![no_start]` and `#![crate_id]`.](https://github.com/rust-lang/rust/pull/134300)  | 
 | 107 | +- [The future incompatibility lint `cenum_impl_drop_cast` has been made into a hard error.](https://github.com/rust-lang/rust/pull/135964) This means it is now an error to cast a field-less enum to an integer if the enum implements `Drop`.  | 
 | 108 | +- [SSE2 is now required for "i686" 32-bit x86 hard-float targets; disabling it causes a warning that will become a hard error eventually.](https://github.com/rust-lang/rust/pull/137037)  | 
 | 109 | +  To compile for pre-SSE2 32-bit x86, use a "i586" target instead.  | 
 | 110 | + | 
 | 111 | +<a id="1.86.0-Internal-Changes"></a>  | 
 | 112 | + | 
 | 113 | +Internal Changes  | 
 | 114 | +----------------  | 
 | 115 | + | 
 | 116 | +These changes do not affect any public interfaces of Rust, but they represent  | 
 | 117 | +significant improvements to the performance or internals of rustc and related  | 
 | 118 | +tools.  | 
 | 119 | + | 
 | 120 | +- [Build the rustc on AArch64 Linux with ThinLTO + PGO.](https://github.com/rust-lang/rust/pull/133807)  | 
 | 121 | +  The ARM 64-bit compiler (AArch64) on Linux is now optimized with ThinLTO and PGO, similar to the optimizations we have already performed for the x86-64 compiler on Linux. This should make it up to 30% faster.  | 
 | 122 | + | 
 | 123 | + | 
1 | 124 | Version 1.85.1 (2025-03-18)  | 
2 | 125 | ==========================  | 
3 | 126 | 
 
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