Rust 1.24.0

Language

• External sysv64 ffi is now available. eg. extern "sysv64" fn foo () {}

Compiler

• rustc now uses 16 codegen units by default for release builds. For the fastest builds, utilize codegen-units=1.
• Added armv4t-unknown-linux-gnueabi target.
• Add aarch64-unknown-openbsd support

Libraries

• str::find::<char> now uses memchr. This should lead to a 10x improvement in performance in the majority of cases.
• OsStr's Debug implementation is now lossless and consistent with Windows.
• time::{SystemTime, Instant} now implement Hash.
• impl From<bool> for AtomicBool
• impl From<{CString, &CStr}> for {Arc<CStr>, Rc<CStr>}
• impl From<{OsString, &OsStr}> for {Arc<OsStr>, Rc<OsStr>}
• impl From<{PathBuf, &Path}> for {Arc<Path>, Rc<Path>}
• float::from_bits now just uses transmute. This provides some optimisations from LLVM.
• Copied AsciiExt methods onto char
• Remove T: Sized requirement on ptr::is_null()
• impl From<RecvError> for {TryRecvError, RecvTimeoutError}
• Optimised f32::{min, max} to generate more efficient x86 assembly
• [u8]::contains now uses memchr which provides a 3x speed improvement

Stabilized APIs

• RefCell::replace
• RefCell::swap
• atomic::spin_loop_hint

The following functions can now be used in a constant expression. eg. let buffer: [u8; size_of::<usize>()];, static COUNTER: AtomicUsize = AtomicUsize::new(1);

• AtomicBool::new
• AtomicUsize::new
• AtomicIsize::new
• AtomicPtr::new
• Cell::new
• {integer}::min_value
• {integer}::max_value
• mem::size_of
• mem::align_of
• ptr::null
• ptr::null_mut
• RefCell::new
• UnsafeCell::new

Cargo

• Added a workspace.default-members config that overrides implied --all in virtual workspaces.
• Enable incremental by default on development builds. Also added configuration keys to Cargo.toml and .cargo/config to disable on a per-project or global basis respectively.

Misc

Compatibility Notes

• Floating point types Debug impl now always prints a decimal point.
• Ipv6Addr now rejects superfluous ::'s in IPv6 addresses This is in accordance with IETF RFC 4291 §2.2.
• Unwinding will no longer go past FFI boundaries, and will instead abort.
• Formatter::flags method is now deprecated. The sign_plus, sign_minus, alternate, and sign_aware_zero_pad should be used instead.
• Leading zeros in tuple struct members is now an error
• column!() macro is one-based instead of zero-based
• fmt::Arguments can no longer be shared across threads
• Access to #[repr(packed)] struct fields is now unsafe
• Cargo sets a different working directory for the compiler