1.87.0 announcement

Author: Mark-Simulacrum

content/Rust-1.87.0.md

@@ -0,0 +1,252 @@
++++
+path = "2025/05/15/Rust-1.87.0"
+title = "Announcing Rust 1.87.0"
+authors = ["The Rust Release Team"]
+aliases = [
+    "2025/05/15/Rust-1.87.0.html",
+    "releases/1.87.0",
+]
+
+[extra]
+release = true
++++
+
+The Rust team is happy to announce a new version of Rust, 1.87.0. 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 1.87.0 with:
+
+```
+$ rustup update stable
+```
+
+If you don't have it already, you can [get `rustup`](https://www.rust-lang.org/install.html) from the appropriate page on our website, and check out the [detailed release notes for 1.87.0](https://doc.rust-lang.org/stable/releases.html#version-1870-2025-04-03).
+
+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](https://github.com/rust-lang/rust/issues/new/choose) any bugs you might come across!
+
+## What's in 1.87.0 stable
+
+### Anonymous pipes
+
+1.87 adds access to anonymous pipes to the standard library. This includes
+integration with `std::process::Command`'s input/output methods.
+
+As a toy example, this program uses pipes to stream data into `cat` and read the output:
+
+```rust
+use std::process::Command;
+use std::io::{pipe, Read, Write};
+
+let (ping_rx, mut ping_tx) = pipe()?;
+let (mut pong_rx, pong_tx) = pipe()?;
+
+// Spawn a process that echoes its input.
+let mut echo_server = Command::new("cat").stdin(ping_rx).stdout(pong_tx).spawn()?;
+
+ping_tx.write_all(b"hello")?;
+// Close to unblock echo_server's reader.
+drop(ping_tx);
+
+let mut buf = String::new();
+// Block until echo_server's writer is closed.
+pong_rx.read_to_string(&mut buf)?;
+assert_eq!(&buf, "hello");
+
+echo_server.wait()?;
+```
+
+### Safe architecture intrinsics
+
+Most `std::arch` intrinsics that are unsafe only due to requiring target
+features to be enabled are now callable in safe code that has those features
+enabled. For example, the following toy program which implements summing an array using
+manual intrinsics can now use safe code for the core loop.
+
+```rust
+#![forbid(unsafe_op_in_unsafe_fn)]
+
+use std::arch::x86_64::*;
+
+fn sum(slice: &[u32]) -> u32 {
+    #[cfg(target_arch = "x86_64")]
+    {
+        if is_x86_feature_detected!("avx2") {
+            // SAFETY: We have detected the feature is enabled at runtime,
+            // so it's safe to call this function.
+            return unsafe { sum_avx2(slice) };
+        }
+    }
+
+    slice.iter().sum()
+}
+
+#[target_feature(enable = "avx2")]
+#[cfg(target_arch = "x86_64")]
+fn sum_avx2(slice: &[u32]) -> u32 {
+    // SAFETY: __m256i and u32 have the same validity.
+    let (prefix, middle, tail) = unsafe { slice.align_to::<__m256i>() };
+    
+    let mut sum = prefix.iter().sum::<u32>();
+    sum += tail.iter().sum::<u32>();
+    
+    // Core loop is now fully safe code in 1.87, because the intrinsics require
+    // matching target features (avx2) to the function definition.
+    let mut base = _mm256_setzero_si256();
+    for e in middle.iter() {
+        base = _mm256_add_epi32(base, *e);
+    }
+    
+    // SAFETY: __m256i and u32 have the same validity.
+    let base: [u32; 8] = unsafe { std::mem::transmute(base) };
+    sum += base.iter().sum::<u32>();
+    
+    sum
+}
+```
+
+### `asm!` jumps to Rust code  
+
+Inline assembly (`asm!`) can now jump to labeled blocks within Rust code. This
+enables more flexible low-level programming, such as implementing optimized
+control flow in OS kernels or interacting with hardware more efficiently. 
+
+- The `asm!` macro now supports a label operand, which acts as a jump target.  
+- The label must be a block expression with a return type of `()` or `!`.  
+- The block executes when jumped to, and execution continues after the `asm!` block.  
+- Using output and label operands in the same `asm!` invocation remains [unstable](https://github.com/rust-lang/rust/issues/119364).  
+
+```rust
+unsafe {
+    asm!(
+        "jmp {}",
+        label {
+            println!("Jumped from asm!");
+        }
+    );
+}
+```
+
+For more details, please consult the [reference](https://doc.rust-lang.org/nightly/reference/inline-assembly.html#r-asm.operand-type.supported-operands.label).
+
+### Precise capturing (`+ use<...>`) in `impl Trait` in trait definitions
+
+This release stabilizes specifying the specific captured generic types and
+lifetimes in trait definitions using `impl Trait` return types. This allows
+using this feature in trait definitions, expanding on the stabilization for
+non-trait functions in
+[1.82](https://blog.rust-lang.org/2024/10/17/Rust-1.82.0/#precise-capturing-use-syntax).
+
+Some example desugarings:
+
+```rust
+trait Foo {
+    fn method<'a>(&'a self) -> impl Sized;
+    
+    // ... desugars to something like:
+    type Implicit1<'a>: Sized;
+    fn method_desugared<'a>(&'a self) -> Self::Implicit1<'a>;
+    
+    // ... whereas with precise capturing ...
+    fn precise<'a>(&'a self) -> impl Sized + use<Self>;
+    
+    // ... desugars to something like:
+    type Implicit2: Sized;
+    fn precise_desugared<'a>(&'a self) -> Self::Implicit2;
+}
+```
+
+### Stabilized APIs
+
+- [`Vec::extract_if`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.extract_if)
+- [`vec::ExtractIf`](https://doc.rust-lang.org/nightly/std/vec/struct.ExtractIf.html)
+- [`LinkedList::extract_if`](https://doc.rust-lang.org/nightly/std/collections/struct.LinkedList.html#method.extract_if)
+- [`linked_list::ExtractIf`](https://doc.rust-lang.org/nightly/std/collections/linked_list/struct.ExtractIf.html)
+- [`<[T]>::split_off`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off)
+- [`<[T]>::split_off_mut`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off_mut)
+- [`<[T]>::split_off_first`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off_first)
+- [`<[T]>::split_off_first_mut`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off_first_mut)
+- [`<[T]>::split_off_last`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off_last)
+- [`<[T]>::split_off_last_mut`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.split_off_last_mut)
+- [`String::extend_from_within`](https://doc.rust-lang.org/stable/alloc/string/struct.String.html#method.extend_from_within)
+- [`os_str::Display`](https://doc.rust-lang.org/nightly/std/ffi/os_str/struct.Display.html)
+- [`OsString::display`](https://doc.rust-lang.org/nightly/std/ffi/struct.OsString.html#method.display)
+- [`OsStr::display`](https://doc.rust-lang.org/nightly/std/ffi/struct.OsStr.html#method.display)
+- [`io::pipe`](https://doc.rust-lang.org/nightly/std/io/fn.pipe.html)
+- [`io::PipeReader`](https://doc.rust-lang.org/nightly/std/io/struct.PipeReader.html)
+- [`io::PipeWriter`](https://doc.rust-lang.org/nightly/std/io/struct.PipeWriter.html)
+- [`impl From<PipeReader> for OwnedHandle`](https://doc.rust-lang.org/nightly/std/os/windows/io/struct.OwnedHandle.html#impl-From%3CPipeReader%3E-for-OwnedHandle)
+- [`impl From<PipeWriter> for OwnedHandle`](https://doc.rust-lang.org/nightly/std/os/windows/io/struct.OwnedHandle.html#impl-From%3CPipeWriter%3E-for-OwnedHandle)
+- [`impl From<PipeReader> for Stdio`](https://doc.rust-lang.org/nightly/std/process/struct.Stdio.html)
+- [`impl From<PipeWriter> for Stdio`](https://doc.rust-lang.org/nightly/std/process/struct.Stdio.html#impl-From%3CPipeWriter%3E-for-Stdio)
+- [`impl From<PipeReader> for OwnedFd`](https://doc.rust-lang.org/nightly/std/os/fd/struct.OwnedFd.html#impl-From%3CPipeReader%3E-for-OwnedFd)
+- [`impl From<PipeWriter> for OwnedFd`](https://doc.rust-lang.org/nightly/std/os/fd/struct.OwnedFd.html#impl-From%3CPipeWriter%3E-for-OwnedFd)
+- [`Box<MaybeUninit<T>>::write`](https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html#method.write)
+- [`impl TryFrom<Vec<u8>> for String`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#impl-TryFrom%3CVec%3Cu8%3E%3E-for-String)
+
+These APIs are now stable in const contexts:
+
+- [`<*const T>::offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.offset_from_unsigned)
+- [`<*const T>::byte_offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.byte_offset_from_unsigned)
+- [`<*mut T>::offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.offset_from_unsigned-1)
+- [`<*mut T>::byte_offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/primitive.pointer.html#method.byte_offset_from_unsigned-1)
+- [`NonNull::offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/ptr/struct.NonNull.html#method.offset_from_unsigned)
+- [`NonNull::byte_offset_from_unsigned`](https://doc.rust-lang.org/nightly/std/ptr/struct.NonNull.html#method.byte_offset_from_unsigned)
+- [`<uN>::cast_signed`](https://doc.rust-lang.org/nightly/std/primitive.usize.html#method.cast_signed)
+- [`NonZero::<uN>::cast_signed`](https://doc.rust-lang.org/nightly/std/num/struct.NonZero.html#method.cast_signed-5).
+- [`<iN>::cast_signed`](https://doc.rust-lang.org/nightly/std/primitive.isize.html#method.cast_signed).
+- [`NonZero::<iN>::cast_unsigned`](https://doc.rust-lang.org/nightly/std/num/struct.NonZero.html#method.cast_unsigned-5).
+- [`<uN>::is_multiple_of`](https://doc.rust-lang.org/nightly/std/primitive.usize.html#method.is_multiple_of)
+- [`<uN>::unbounded_shl`](https://doc.rust-lang.org/nightly/std/primitive.usize.html#method.unbounded_shl)
+- [`<uN>::unbounded_shr`](https://doc.rust-lang.org/nightly/std/primitive.usize.html#method.unbounded_shr)
+- [`<iN>::unbounded_shl`](https://doc.rust-lang.org/nightly/std/primitive.isize.html#method.unbounded_shl)
+- [`<iN>::unbounded_shr`](https://doc.rust-lang.org/nightly/std/primitive.isize.html#method.unbounded_shr)
+- [`<str>::from_utf8`](https://doc.rust-lang.org/nightly/std/primitive.str.html#method.from_utf8)
+- [`<str>::from_utf8_mut`](https://doc.rust-lang.org/nightly/std/primitive.str.html#method.from_utf8_mut)
+- [`<str>::from_utf8_unchecked`](https://doc.rust-lang.org/nightly/std/primitive.str.html#method.from_utf8_unchecked)
+- [`<str>::from_utf8_unchecked_mut`](https://doc.rust-lang.org/nightly/std/primitive.str.html#method.from_utf8_unchecked_mut)
+- [`<[T]>::copy_from_slice`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.copy_from_slice)
+- [`SocketAddr::set_ip`](https://doc.rust-lang.org/nightly/std/net/enum.SocketAddr.html#method.set_ip)
+- [`SocketAddr::set_port`](https://doc.rust-lang.org/nightly/std/net/enum.SocketAddr.html#method.set_port),
+- [`SocketAddrV4::set_ip`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV4.html#method.set_ip)
+- [`SocketAddrV4::set_port`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV4.html#method.set_port),
+- [`SocketAddrV6::set_ip`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV6.html#method.set_ip)
+- [`SocketAddrV6::set_port`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV6.html#method.set_port)
+- [`SocketAddrV6::set_flowinfo`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV6.html#method.set_flowinfo)
+- [`SocketAddrV6::set_scope_id`](https://doc.rust-lang.org/nightly/std/net/struct.SocketAddrV6.html#method.set_scope_id)
+- [`char::is_digit`](https://doc.rust-lang.org/nightly/std/primitive.char.html#method.is_digit)
+- [`char::is_whitespace`](https://doc.rust-lang.org/nightly/std/primitive.char.html#method.is_whitespace)
+- [`<iN>:midpoint`](https://doc.rust-lang.org/std/primitive.isize.html#method.midpoint)
+- [`<[[T; N]]>::as_flattened`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_flattened)
+- [`<[[T; N]]>::as_flattened_mut`](https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.as_flattened_mut) 
+- [`<str>::from_utf8_mut`](https://doc.rust-lang.org/nightly/std/primitive.str.html#method.from_utf8_mut)
+- [`core::str::from_utf8_mut`](https://doc.rust-lang.org/nightly/std/str/fn.from_utf8_mut.html)
+- [`String::into_bytes`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.into_bytes)
+- [`String::as_str`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.as_str)
+- [`String::capacity`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.capacity)
+- [`String::as_bytes`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.as_bytes)
+- [`String::len`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.len)
+- [`String::is_empty`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.is_empty)
+- [`String::as_mut_str`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.as_mut_str)
+- [`String::as_mut_vec`](https://doc.rust-lang.org/nightly/std/string/struct.String.html#method.as_mut_vec)
+- [`Vec::as_ptr`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.as_ptr-1)
+- [`Vec::as_slice`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.as_slice)
+- [`Vec::capacity`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.capacity)
+- [`Vec::len`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.len)
+- [`Vec::is_empty`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.is_empty)
+- [`Vec::as_mut_slice`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.as_mut_slice)
+- [`Vec::as_mut_ptr`](https://doc.rust-lang.org/nightly/std/vec/struct.Vec.html#method.as_mut_ptr)
+
+### `i586-pc-windows-msvc` target removal
+
+The tier-2 target `i586-pc-windows-msvc` has been removed. Its difference to the much more popular `i686-pc-windows-msvc` is that it does not require SSE2 instruction support, but Windows 10, the minimum required OS version of all `windows` targets (except the `win7` targets), requires SSE2 instructions itself.
+
+All users currently targeting `i586-pc-windows-msvc` should migrate to `i686-pc-windows-msvc`.
+
+You can check the [Major Change Proposal](https://github.com/rust-lang/compiler-team/issues/840) for more information.
+
+### Other changes
+
+Check out everything that changed in [Rust](https://github.com/rust-lang/rust/releases/tag/1.87.0), [Cargo](https://doc.rust-lang.org/nightly/cargo/CHANGELOG.html#cargo-187-2025-05-15), and [Clippy](https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-187).
+
+## Contributors to 1.87.0
+
+Many people came together to create Rust 1.87.0. We couldn't have done it without all of you. [Thanks!](https://thanks.rust-lang.org/rust/1.87.0/)