Rust 1.13.0

Language

• Stabilize the ? operator. ? is a simple way to propagate errors, like the try! macro, described in RFC 0243.
• Stabilize macros in type position. Described in RFC 873.
• Stabilize attributes on statements. Described in RFC 0016.
• Fix #[derive] for empty tuple structs/variants
• Fix lifetime rules for 'if' conditions
• Avoid loading and parsing unconfigured non-inline modules

Compiler

• Add the -C link-arg argument
• Remove the old AST-based backend from rustc_trans
• Don't enable NEON by default on armv7 Linux
• Fix debug line number info for macro expansions
• Do not emit "class method" debuginfo for types that are not DICompositeType
• Warn about multiple conflicting #[repr] hints
• When sizing DST, don't double-count nested struct prefixes
• Default RUST_MIN_STACK to 16MiB for now
• Improve rlib metadata format. Reduces rlib size significantly.
• Reject macros with empty repetitions to avoid infinite loop
• Expand macros without recursing to avoid stack overflows

Diagnostics

• Replace macro backtraces with labeled local uses
• Improve error message for misplaced doc comments
• Buffer unix and lock windows to prevent message interleaving
• Update lifetime errors to specifically note temporaries
• Special case a few colors for Windows
• Suggest use self when such an import resolves
• Be more specific when type parameter shadows primitive type
• Many minor improvements

Compile-time Optimizations

• Compute and cache HIR hashes at beginning
• Don't hash types in loan paths
• Cache projections in trans
• Optimize the parser's last token handling
• Only instantiate #[inline] functions in codegen units referencing them. This leads to big improvements in cases where crates export define many inline functions without using them directly.
• Lazily allocate TypedArena's first chunk
• Don't allocate during default HashSet creation

Stabilized APIs

• checked_abs
• wrapping_abs
• overflowing_abs
• RefCell::try_borrow
• RefCell::try_borrow_mut

Libraries

• Add assert_ne! and debug_assert_ne!
• Make vec_deque::Drain, hash_map::Drain, and hash_set::Drain covariant
• Implement AsRef<[T]> for std::slice::Iter
• Implement Debug for std::vec::IntoIter
• CString: avoid excessive growth just to 0-terminate
• Implement CoerceUnsized for {Cell, RefCell, UnsafeCell}
• Use arc4rand on FreeBSD
• memrchr: Correct aligned offset computation
• Improve Demangling of Rust Symbols
• Use monotonic time in condition variables
• Implement Debug for std::path::{Components,Iter}
• Implement conversion traits for char
• Fix illegal instruction caused by overflow in channel cloning
• Zero first byte of CString on drop
• Inherit overflow checks for sum and product
• Add missing Eq implementations
• Implement Debug for DirEntry
• When getaddrinfo returns EAI_SYSTEM retrieve actual error from errno
• SipHasher is deprecated. Use DefaultHasher.
• Implement more traits for std::io::ErrorKind
• Optimize BinaryHeap bounds checking
• Work around pointer aliasing issue in Vec::extend_from_slice, extend_with_element
• Fix overflow checking in unsigned pow()

Cargo

• This release includes security fixes to both curl and OpenSSL.
• Fix transitive doctests when panic=abort
• Add --all-features flag to cargo
• Reject path-based dependencies in cargo package
• Don't parse the home directory more than once
• Don't try to generate Cargo.lock on empty workspaces
• Update OpenSSL to 1.0.2j
• Add license and license_file to cargo metadata output
• Make crates-io registry URL optional in config; ignore all changes to source.crates-io
• Don't download dependencies from other platforms
• Build transitive dev-dependencies when needed
• Add support for per-target rustflags in .cargo/config
• Avoid updating registry when adding existing deps
• Warn about path overrides that won't work
• Use workspaces during cargo install
• Leak mspdbsrv.exe processes on Windows
• Add --message-format flag
• Pass target environment for rustdoc
• Use CommandExt::exec for cargo run on Unix
• Update curl and curl-sys
• Call rustdoc test with the correct cfg flags of a package

Tooling

• rustdoc: Add the --sysroot argument
• rustdoc: Fix a couple of issues with the search results
• rustdoc: remove the ! from macro URLs and titles
• gdb: Fix pretty-printing special-cased Rust types
• rustdoc: Filter more incorrect methods inherited through Deref

Misc

• Remove unmaintained style guide
• Add s390x support
• Initial work at Haiku OS support
• Add mips-uclibc targets
• Crate-ify compiler-rt into compiler-builtins
• Add rustc version info (git hash + date) to dist tarball
• Many documentation improvements

Compatibility Notes

• SipHasher is deprecated. Use DefaultHasher.
• Deny (by default) transmuting from fn item types to pointer-sized types. Continuing the long transition to zero-sized fn items, per [RFC 401](https://github.com/rust-lang/rfcs/blob/master/text/0...

Rust 1.12.1

Regression Fixes

• ICE: 'rustc' panicked at 'assertion failed: concrete_substs.is_normalized_for_trans()' #36381
• Confusion with double negation and booleans
• rustc 1.12.0 fails with SIGSEGV in release mode (syn crate 0.8.0)
• Rustc 1.12.0 Windows build of ethcore crate fails with LLVM error
• 1.12.0: High memory usage when linking in release mode with debug info
• Corrupted memory after updated to 1.12
• "Let NullaryConstructor = something;" causes internal compiler error: "tried to overwrite interned AdtDef"
• Fix ICE: inject bitcast if types mismatch for invokes/calls/stores
• debuginfo: Handle spread_arg case in MIR-trans in a more stable way.

Rust 1.12.0

Highlights

• rustc translates code to LLVM IR via its own "middle" IR (MIR). This translation pass is far simpler than the previous AST->LLVM pass, and creates opportunities to perform new optimizations directly on the MIR. It was previously described on the Rust blog.
• rustc presents a new, more readable error format, along with machine-readable JSON error output for use by IDEs. Most common editors supporting Rust have been updated to work with it. It was previously described on the Rust blog.

Compiler

• rustc translates code to LLVM IR via its own "middle" IR (MIR). This translation pass is far simpler than the previous AST->LLVM pass, and creates opportunities to perform new optimizations directly on the MIR. It was previously described on the Rust blog.
• Print the Rust target name, not the LLVM target name, with --print target-list
• The computation of TypeId is correct in some cases where it was previously producing inconsistent results
• The mips-unknown-linux-gnu target uses hardware floating point by default
• The rustc arguments, --print target-cpus, --print target-features, --print relocation-models, and --print code-models print the available options to the -C target-cpu, -C target-feature, -C relocation-model and -C code-model code generation arguments
• rustc supports three new MUSL targets on ARM: arm-unknown-linux-musleabi, arm-unknown-linux-musleabihf, and armv7-unknown-linux-musleabihf. These targets produce statically-linked binaries. There are no binary release builds yet though.

Diagnostics

• rustc presents a new, more readable error format, along with machine-readable JSON error output for use by IDEs. Most common editors supporting Rust have been updated to work with it. It was previously described on the Rust blog.
• In error descriptions, references are now described in plain English, instead of as "&-ptr"
• In error type descriptions, unknown numeric types are named {integer} or {float} instead of _
• rustc emits a clearer error when inner attributes follow a doc comment

Language

• macro_rules! invocations can be made within macro_rules! invocations
• macro_rules! meta-variables are hygienic
• macro_rules! tt matchers can be reparsed correctly, making them much more useful
• macro_rules! stmt matchers correctly consume the entire contents when inside non-braces invocations
• Semicolons are properly required as statement delimiters inside macro_rules! invocations
• cfg_attr works on path attributes

Stabilized APIs

• Cell::as_ptr
• RefCell::as_ptr
• IpAddr::is_unspecified
• IpAddr::is_loopback
• IpAddr::is_multicast
• Ipv4Addr::is_unspecified
• Ipv6Addr::octets
• LinkedList::contains
• VecDeque::contains
• ExitStatusExt::from_raw. Both on Unix and Windows.
• Receiver::recv_timeout
• RecvTimeoutError
• BinaryHeap::peek_mut
• PeekMut
• iter::Product
• iter::Sum
• OccupiedEntry::remove_entry
• VacantEntry::into_key

Libraries

• The format! macro and friends now allow a single argument to be formatted in multiple styles
• The lifetime bounds on [T]::binary_search_by and [T]::binary_search_by_key have been adjusted to be more flexible
• Option implements From for its contained type
• Cell, RefCell and UnsafeCell implement From for their contained type
• RwLock panics if the reader count overflows
• vec_deque::Drain, hash_map::Drain and hash_set::Drain are covariant
• vec::Drain and binary_heap::Drain are covariant
• Cow<str> implements FromIterator for char, &str and String
• Sockets on Linux are correctly closed in subprocesses via SOCK_CLOEXEC
• hash_map::Entry, hash_map::VacantEntry and hash_map::OccupiedEntry implement Debug
• btree_map::Entry, btree_map::VacantEntry and btree_map::OccupiedEntry implement Debug
• String implements AddAssign
• Variadic extern fn pointers implement the Clone, PartialEq, Eq, PartialOrd, Ord, Hash, fmt::Pointer, and fmt::Debug traits
• FileType implements Debug
• References to Mutex and RwLock are unwind-safe
• mpsc::sync_channel Receivers return any available message before reporting a disconnect
• Unicode definitions have been updated to 9.0
• env iterators implement DoubleEndedIterator

Cargo

• Support local mirrors of registries
• Add support for command aliases
• Allow opt-level="s" / opt-level="z" in profile overrides
• Make cargo doc --open --target work as expected
• Speed up noop registry updates
• Update OpenSSL
• Fix --panic=abort with plugins
• Always pass -C metadata to the compiler
• Fix depending on git repos with workspaces
• Add a --lib flag to cargo new
• Add http.cainfo for custom certs
• Indicate the compilation profile after compiling
• Allow enabling features for dependencies with --features
• Add --jobs flag to cargo package
• Add --dry-run to cargo publish
• Add support for RUSTDOCFLAGS

Performance

• panic::catch_unwind is more optimized
• panic::catch_unwind no longer accesses thread-local storage on entry

Tooling

• Test binaries now support a --test-threads argument to specify the number of threads used to run tests, and which acts the same as the RUST_TEST_THREADS environment variable
• The test runner now emits a warning when tests run over 60 seconds
• rustdoc: Fix methods in search results
• rust-lldb warns about unsupported versions of LLDB
• [Rust releases now come with source p...

Rust 1.11.0

Language

• Support nested cfg_attr attributes
• Allow statement-generating braced macro invocations at the end of blocks
• Macros can be expanded inside of trait definitions
• #[macro_use] works properly when it is itself expanded from a macro

Stabilized APIs

• BinaryHeap::append
• BTreeMap::append
• BTreeMap::split_off
• BTreeSet::append
• BTreeSet::split_off
• f32::to_degrees (in libcore - previously stabilized in libstd)
• f32::to_radians (in libcore - previously stabilized in libstd)
• f64::to_degrees (in libcore - previously stabilized in libstd)
• f64::to_radians (in libcore - previously stabilized in libstd)
• Iterator::sum
• Iterator::product
• Cell::get_mut
• RefCell::get_mut

Libraries

• The thread_local! macro supports multiple definitions in a single invocation, and can apply attributes
• Cow implements Default
• Wrapping implements binary, octal, lower-hex and upper-hex Display formatting
• The range types implement Hash
• lookup_host ignores unknown address types
• assert_eq! accepts a custom error message, like assert! does
• The main thread is now called "main" instead of "<main>"

Cargo

• Disallow specifying features of transitive deps
• Add color support for Windows consoles
• Fix harness = false on [lib] sections
• Don't panic when links contains a '.'
• Build scripts can emit warnings, and -vv prints warnings for all crates.
• Ignore file locks on OS X NFS mounts
• Don't warn about package.metadata keys. This provides room for expansion by arbitrary tools.
• Add support for cdylib crate types
• Prevent publishing crates when files are dirty
• Don't fetch all crates on clean
• Propagate --color option to rustc
• Fix cargo doc --open on Windows
• Improve autocompletion
• Configure colors of stderr as well as stdout

Performance

• Caching projections speeds up type check dramatically for some workloads
• The default HashMap hasher is SipHash 1-3 instead of SipHash 2-4 This hasher is faster, but is believed to provide sufficient protection from collision attacks.
• Comparison of Ipv4Addr is 10x faster

Rustdoc

• Fix empty implementation section on some module pages
• Fix inlined renamed re-exports in import lists
• Fix search result layout for enum variants and struct fields
• Fix issues with source links to external crates
• Fix redirect pages for renamed re-exports

Tooling

• rustc is better at finding the MSVC toolchain
• When emitting debug info, rustc emits frame pointers for closures, shims and glue, as it does for all other functions
• rust-lldb warns about unsupported versions of LLDB
• Many more errors have been given error codes and extended explanations
• API documentation continues to be improved, with many new examples

Misc

• rustc no longer hangs when dependencies recursively re-export submodules
• rustc requires LLVM 3.7+
• The 'How Safe and Unsafe Interact' chapter of The Rustonomicon was rewritten
• rustc support 16-bit pointer sizes. No targets use this yet, but it works toward AVR support.

Compatibility Notes

• consts and statics may not have unsized types
• The new follow-set rules that place restrictions on macro_rules! in order to ensure syntax forward-compatibility have been enabled This was an amendment to RFC 550, and has been a warning since 1.10.
• cfg attribute process has been refactored to fix various bugs. This causes breakage in some corner cases.

Rust 1.10.0

Language

• Copy types are required to have a trivial implementation of Clone. RFC 1521.
• Single-variant enums support the #[repr(..)] attribute.
• Fix #[derive(RustcEncodable)] in the presence of other encode methods.
• panic! can be converted to a runtime abort with the -C panic=abort flag. RFC 1513.
• Add a new crate type, 'cdylib'. cdylibs are dynamic libraries suitable for loading by non-Rust hosts. RFC 1510. Note that Cargo does not yet directly support cdylibs.

Stabilized APIs

• os::windows::fs::OpenOptionsExt::access_mode
• os::windows::fs::OpenOptionsExt::share_mode
• os::windows::fs::OpenOptionsExt::custom_flags
• os::windows::fs::OpenOptionsExt::attributes
• os::windows::fs::OpenOptionsExt::security_qos_flags
• os::unix::fs::OpenOptionsExt::custom_flags
• sync::Weak::new
• Default for sync::Weak
• panic::set_hook
• panic::take_hook
• panic::PanicInfo
• panic::PanicInfo::payload
• panic::PanicInfo::location
• panic::Location
• panic::Location::file
• panic::Location::line
• ffi::CStr::from_bytes_with_nul
• ffi::CStr::from_bytes_with_nul_unchecked
• ffi::FromBytesWithNulError
• fs::Metadata::modified
• fs::Metadata::accessed
• fs::Metadata::created
• sync::atomic::Atomic{Usize,Isize,Bool,Ptr}::compare_exchange
• sync::atomic::Atomic{Usize,Isize,Bool,Ptr}::compare_exchange_weak
• collections::{btree,hash}_map::{Occupied,Vacant,}Entry::key
• os::unix::net::{UnixStream, UnixListener, UnixDatagram, SocketAddr}
• SocketAddr::is_unnamed
• SocketAddr::as_pathname
• UnixStream::connect
• UnixStream::pair
• UnixStream::try_clone
• UnixStream::local_addr
• UnixStream::peer_addr
• UnixStream::set_read_timeout
• UnixStream::set_write_timeout
• UnixStream::read_timeout
• UnixStream::write_timeout
• UnixStream::set_nonblocking
• UnixStream::take_error
• UnixStream::shutdown
• Read/Write/RawFd impls for UnixStream
• UnixListener::bind
• UnixListener::accept
• UnixListener::try_clone
• UnixListener::local_addr
• UnixListener::set_nonblocking
• UnixListener::take_error
• UnixListener::incoming
• RawFd impls for UnixListener
• UnixDatagram::bind
• UnixDatagram::unbound
• UnixDatagram::pair
• UnixDatagram::connect
• UnixDatagram::try_clone
• UnixDatagram::local_addr
• UnixDatagram::peer_addr
• UnixDatagram::recv_from
• UnixDatagram::recv
• UnixDatagram::send_to
• UnixDatagram::send
• UnixDatagram::set_read_timeout
• UnixDatagram::set_write_timeout
• UnixDatagram::read_timeout
• UnixDatagram::write_timeout
• UnixDatagram::set_nonblocking
• UnixDatagram::take_error
• UnixDatagram::shutdown
• RawFd impls for UnixDatagram
• {BTree,Hash}Map::values_mut
• <[_]>::binary_search_by_key

Libraries

• The abs_sub method of floats is deprecated. The semantics of this minor method are subtle and probably not what most people want.
• Add implementation of Ord for Cell and RefCell where T: Ord.
• On Linux, if HashMaps can't be initialized with getrandom they will fall back to /dev/urandom temporarily to avoid blocking during early boot.
• Implemented negation for wrapping numerals.
• Implement Clone for binary_heap::IntoIter.
• Implement Display and Hash for std::num::Wrapping.
• Add Default implementation for &CStr, CString.
• Implement From<Vec<T>> and Into<Vec<T>> for VecDeque<T>.
• Implement Default for UnsafeCell, fmt::Error, Condvar, Mutex, RwLock.

Cargo

• Cargo.toml supports the profile.*.panic option. This controls the runtime behavior of the panic! macro and can be either "unwind" (the default), or "abort". RFC 1513.
• Don't throw away errors with -p arguments.
• Report status to stderr instead of stdout.
• Build scripts are passed a CARGO_MANIFEST_LINKS environment variable that corresponds to the links field of the manifest.
• Ban keywords from crate names.
• Canonicalize CARGO_HOME on Windows.
• Retry network requests. By default they are retried twice, which can be customized with the net.retry value in .cargo/config.
• [Don't print extra error info for failing subcommands](rust-lang/cargo#267...

Rust 1.9.0

Language

• The #[deprecated] attribute when applied to an API will generate warnings when used. The warnings may be suppressed with #[allow(deprecated)]. RFC 1270.
• fn item types are zero sized, and each fn names a unique type. This will break code that transmutes fns, so calling transmute on a fn type will generate a warning for a few cycles, then will be converted to an error.
• Field and method resolution understand visibility, so private fields and methods cannot prevent the proper use of public fields and methods.
• The parser considers unicode codepoints in the PATTERN_WHITE_SPACE category to be whitespace.

Stabilized APIs

• std::panic
• std::panic::catch_unwind (renamed from recover)
• std::panic::resume_unwind (renamed from propagate)
• std::panic::AssertUnwindSafe (renamed from AssertRecoverSafe)
• std::panic::UnwindSafe (renamed from RecoverSafe)
• str::is_char_boundary
• <*const T>::as_ref
• <*mut T>::as_ref
• <*mut T>::as_mut
• AsciiExt::make_ascii_uppercase
• AsciiExt::make_ascii_lowercase
• char::decode_utf16
• char::DecodeUtf16
• char::DecodeUtf16Error
• char::DecodeUtf16Error::unpaired_surrogate
• BTreeSet::take
• BTreeSet::replace
• BTreeSet::get
• HashSet::take
• HashSet::replace
• HashSet::get
• OsString::with_capacity
• OsString::clear
• OsString::capacity
• OsString::reserve
• OsString::reserve_exact
• OsStr::is_empty
• OsStr::len
• std::os::unix::thread
• RawPthread
• JoinHandleExt
• JoinHandleExt::as_pthread_t
• JoinHandleExt::into_pthread_t
• HashSet::hasher
• HashMap::hasher
• CommandExt::exec
• File::try_clone
• SocketAddr::set_ip
• SocketAddr::set_port
• SocketAddrV4::set_ip
• SocketAddrV4::set_port
• SocketAddrV6::set_ip
• SocketAddrV6::set_port
• SocketAddrV6::set_flowinfo
• SocketAddrV6::set_scope_id
• slice::copy_from_slice
• ptr::read_volatile
• ptr::write_volatile
• OpenOptions::create_new
• TcpStream::set_nodelay
• TcpStream::nodelay
• TcpStream::set_ttl
• TcpStream::ttl
• TcpStream::set_only_v6
• TcpStream::only_v6
• TcpStream::take_error
• TcpStream::set_nonblocking
• TcpListener::set_ttl
• TcpListener::ttl
• TcpListener::set_only_v6
• TcpListener::only_v6
• TcpListener::take_error
• TcpListener::set_nonblocking
• UdpSocket::set_broadcast
• UdpSocket::broadcast
• UdpSocket::set_multicast_loop_v4
• UdpSocket::multicast_loop_v4
• UdpSocket::set_multicast_ttl_v4
• UdpSocket::multicast_ttl_v4
• UdpSocket::set_multicast_loop_v6
• UdpSocket::multicast_loop_v6
• UdpSocket::set_multicast_ttl_v6
• UdpSocket::multicast_ttl_v6
• UdpSocket::set_ttl
• UdpSocket::ttl
• UdpSocket::set_only_v6
• UdpSocket::only_v6
• UdpSocket::join_multicast_v4
• UdpSocket::join_multicast_v6
• UdpSocket::leave_multicast_v4
• UdpSocket::leave_multicast_v6
• UdpSocket::take_error
• [`UdpSocket:...

Rust 1.8.0

Language

• Rust supports overloading of compound assignment statements like += by implementing the AddAssign, SubAssign, MulAssign, DivAssign, RemAssign, BitAndAssign, BitOrAssign, BitXorAssign, ShlAssign, or ShrAssign traits. RFC 953.
• Empty structs can be defined with braces, as in struct Foo { }, in addition to the non-braced form, struct Foo;. RFC 218.

Libraries

• Stabilized APIs:
  • str::encode_utf16 (renamed from utf16_units)
  • str::EncodeUtf16 (renamed from Utf16Units)
  • Ref::map
  • RefMut::map
  • ptr::drop_in_place
  • time::Instant
  • time::SystemTime
  • Instant::now
  • Instant::duration_since (renamed from duration_from_earlier)
  • Instant::elapsed
  • SystemTime::now
  • SystemTime::duration_since (renamed from duration_from_earlier)
  • SystemTime::elapsed
  • Various Add/Sub impls for Time and SystemTime
  • SystemTimeError
  • SystemTimeError::duration
  • Various impls for SystemTimeError
  • UNIX_EPOCH
  • AddAssign, SubAssign, MulAssign, DivAssign, RemAssign, BitAndAssign, BitOrAssign, BitXorAssign, ShlAssign, ShrAssign.
• The write! and writeln! macros correctly emit errors if any of their arguments can't be formatted.
• Various I/O functions support large files on 32-bit Linux.
• The Unix-specific raw modules, which contain a number of redefined C types are deprecated, including os::raw::unix, os::raw::macos, and os::raw::linux. These modules defined types such as ino_t and dev_t. The inconsistency of these definitions across platforms was making it difficult to implement std correctly. Those that need these definitions should use the libc crate. RFC 1415.
• The Unix-specific MetadataExt traits, including os::unix::fs::MetadataExt, which expose values such as inode numbers no longer return platform-specific types, but instead return widened integers. RFC 1415.
• btree_set::{IntoIter, Iter, Range} are covariant.
• Atomic loads and stores are not volatile.
• All types in sync::mpsc implement fmt::Debug.

Performance

• Inlining hash functions lead to a 3% compile-time improvement in some workloads.
• When using jemalloc, its symbols are unprefixed so that it overrides the libc malloc implementation. This means that for rustc, LLVM is now using jemalloc, which results in a 6% compile-time improvement on a specific workload.
• Avoid quadratic growth in function size due to cleanups.

Misc

• 32-bit MSVC builds finally implement unwinding. i686-pc-windows-msvc is now considered a tier-1 platform.
• The --print targets flag prints a list of supported targets.
• The --print cfg flag prints the cfgs defined for the current target.
• rustc can be built with an new Cargo-based build system, written in Rust. It will eventually replace Rust's Makefile-based build system. To enable it configure with configure --rustbuild.
• Errors for non-exhaustive match patterns now list up to 3 missing variants while also indicating the total number of missing variants if more than 3.
• Executable stacks are disabled on Linux and BSD.
• The Rust Project now publishes binary releases of the standard library for a number of tier-2 targets: armv7-unknown-linux-gnueabihf, powerpc-unknown-linux-gnu, powerpc64-unknown-linux-gnu, powerpc64le-unknown-linux-gnu x86_64-rumprun-netbsd. These can be installed with tools such as multirust.

Cargo

• cargo init creates a new Cargo project in the current directory. It is otherwise like cargo new.
• Cargo has configuration keys for -v and --color. verbose and color, respectively, go in the [term] section of .cargo/config.
• Configuration keys that evaluate to strings or integers can be set via environment variables. For example the build.jobs key can be set via CARGO_BUILD_JOBS. Environment variables take precedence over config files.
• Target-specific dependencies support Rust cfg syntax for describing targets so that dependencies for multiple targets can be specified together. RFC 1361.
• The environment variables CARGO_TARGET_ROOT, RUSTC, and RUSTDOC take precedence over the build.target-dir, build.rustc, and build.rustdoc configuration values.
• The child process tree is killed on Windows when Cargo is killed.
• The build.target configuration value sets the target platform, like --target.

Compatibility Notes

• Unstable compiler flags have been further restricted. Since 1.0 -Z flags have been considered unstable, and other flags that were considered unstable additionally required passing -Z unstable-options to access. Unlike unstable language and library features though, these options have been accessible on the stable release channel. Going forward, new unstable flags will not be available on the stable release channel, and old unstable flags will warn about their usage. In the future, all unstable flags will be unavailable on the stable release channel.
• It is no longer possible to match on empty enum variants using the Variant(..) syntax. This has been a warning since 1.6.
• The Unix-specific MetadataExt traits, including os::unix::fs::MetadataExt, which expose values such as inode numbers no longer return platform-specific types, but instead return widened integers. RFC 1415.
• Modules sourced from the filesystem cannot appear within arbitrary blocks, but only within other modules.
• --cfg compiler flags are parsed strictly as identifiers.
• On Unix, [stack overflow triggers a runtime abort instead...

Rust 1.7.0

Libraries

• Stabilized APIs
  • Path
    • Path::strip_prefix (renamed from relative_from)
    • path::StripPrefixError (new error type returned from strip_prefix)
  • Ipv4Addr
    • Ipv4Addr::is_loopback
    • Ipv4Addr::is_private
    • Ipv4Addr::is_link_local
    • Ipv4Addr::is_multicast
    • Ipv4Addr::is_broadcast
    • Ipv4Addr::is_documentation
  • Ipv6Addr
    • Ipv6Addr::is_unspecified
    • Ipv6Addr::is_loopback
    • Ipv6Addr::is_multicast
  • Vec
    • Vec::as_slice
    • Vec::as_mut_slice
  • String
    • String::as_str
    • String::as_mut_str
  • Slices
    • <[T]>::clone_from_slice, which now requires the two slices to be the same length
    • <[T]>::sort_by_key
  • checked, saturated, and overflowing operations
    • i32::checked_rem, i32::checked_neg, i32::checked_shl, i32::checked_shr
    • i32::saturating_mul
    • i32::overflowing_add, i32::overflowing_sub, i32::overflowing_mul, i32::overflowing_div
    • i32::overflowing_rem, i32::overflowing_neg, i32::overflowing_shl, i32::overflowing_shr
    • u32::checked_rem, u32::checked_neg, u32::checked_shl, u32::checked_shl
    • u32::saturating_mul
    • u32::overflowing_add, u32::overflowing_sub, u32::overflowing_mul, u32::overflowing_div
    • u32::overflowing_rem, u32::overflowing_neg, u32::overflowing_shl, u32::overflowing_shr
    • and checked, saturated, and overflowing operations for other primitive types
  • FFI
    • ffi::IntoStringError
    • CString::into_string
    • CString::into_bytes
    • CString::into_bytes_with_nul
    • From<CString> for Vec<u8>
  • IntoStringError
    • IntoStringError::into_cstring
    • IntoStringError::utf8_error
    • Error for IntoStringError
  • Hashing
    • std::hash::BuildHasher
    • BuildHasher::Hasher
    • BuildHasher::build_hasher
    • std::hash::BuildHasherDefault
    • HashMap::with_hasher
    • HashMap::with_capacity_and_hasher
    • HashSet::with_hasher
    • HashSet::with_capacity_and_hasher
    • std::collections::hash_map::RandomState
    • RandomState::new
• Validating UTF-8 is faster by a factor of between 7 and 14x for ASCII input. This means that creating Strings and strs from bytes is faster.
• The performance of LineWriter (and thus io::stdout) was improved by using memchr to search for newlines.
• f32::to_degrees and f32::to_radians are stable. The f64 variants were stabilized previously.
• BTreeMap was rewritten to use less memory and improve the performance of insertion and iteration, the latter by as much as 5x.
• BTreeSet and its iterators, Iter, IntoIter, and Range are covariant over their contained type.
• LinkedList and its iterators, Iter and IntoIter are covariant over their contained type.
• str::replace now accepts a Pattern, like other string searching methods.
• Any is implemented for unsized types.
• Hash is implemented for Duration.

Misc

• When running tests with --test, rustdoc will pass --cfg arguments to the compiler.
• The compiler is built with RPATH information by default. This means that it will be possible to run rustc when installed in unusual configurations without configuring the dynamic linker search path explicitly.
• rustc passes --enable-new-dtags to GNU ld. This makes any RPATH entries (emitted with -C rpath) not take precedence over LD_LIBRARY_PATH.

Cargo

• cargo rustc accepts a --profile flag that runs rustc under any of the compilation profiles, 'dev', 'bench', or 'test'.
• The rerun-if-changed build script directive no longer causes the build script to incorrectly run twice in certain scenarios.

Compatibility Notes

• Soundness fixes to the interactions between associated types and lifetimes, specified in RFC 1214, now generate errors for code that violates the new rules. This is a significant change that is known to break existing code, so it has emitted warnings for the new error cases since 1.4 to give crate authors time to adapt. The details of what is changing are subtle; read the RFC for more.
• Several bugs in the compiler's visibility calculations were fixed. Since this was found to br...

Rust 1.6.0

Language

• The #![no_std] attribute causes a crate to not be linked to the standard library, but only the core library, as described in RFC 1184. The core library defines common types and traits but has no platform dependencies whatsoever, and is the basis for Rust software in environments that cannot support a full port of the standard library, such as operating systems. Most of the core library is now stable.

Libraries

• Stabilized APIs: Read::read_exact, ErrorKind::UnexpectedEof (renamed from UnexpectedEOF), fs::DirBuilder, fs::DirBuilder::new, fs::DirBuilder::recursive, fs::DirBuilder::create, os::unix::fs::DirBuilderExt, os::unix::fs::DirBuilderExt::mode, vec::Drain, vec::Vec::drain, string::Drain, string::String::drain, vec_deque::Drain, vec_deque::VecDeque::drain, collections::hash_map::Drain, collections::hash_map::HashMap::drain, collections::hash_set::Drain, collections::hash_set::HashSet::drain, collections::binary_heap::Drain, collections::binary_heap::BinaryHeap::drain, Vec::extend_from_slice (renamed from push_all), Mutex::get_mut, Mutex::into_inner, RwLock::get_mut, RwLock::into_inner, Iterator::min_by_key (renamed from min_by), Iterator::max_by_key (renamed from max_by).
• The core library is stable, as are most of its APIs.
• The assert_eq! macro supports arguments that don't implement Sized, such as arrays. In this way it behaves more like assert!.
• Several timer functions that take duration in milliseconds are deprecated in favor of those that take Duration. These include Condvar::wait_timeout_ms, thread::sleep_ms, and thread::park_timeout_ms.
• The algorithm by which Vec reserves additional elements was tweaked to not allocate excessive space while still growing exponentially.
• From conversions are implemented from integers to floats in cases where the conversion is lossless. Thus they are not implemented for 32-bit ints to f32, nor for 64-bit ints to f32 or f64. They are also not implemented for isize and usize because the implementations would be platform-specific. From is also implemented from f32 to f64.
• From<&Path> and From<PathBuf> are implemented for Cow<Path>.
• From<T> is implemented for Box<T>, Rc<T> and Arc<T>.
• IntoIterator is implemented for &PathBuf and &Path.
• BinaryHeap was refactored for modest performance improvements.
• Sorting slices that are already sorted is 50% faster in some cases.

Cargo

• Cargo will look in $CARGO_HOME/bin for subcommands by default.
• Cargo build scripts can specify their dependencies by emitting the rerun-if-changed key.
• crates.io will reject publication of crates with dependencies that have a wildcard version constraint. Crates with wildcard dependencies were seen to cause a variety of problems, as described in RFC 1241. Since 1.5 publication of such crates has emitted a warning.
• cargo clean accepts a --release flag to clean the release folder. A variety of artifacts that Cargo failed to clean are now correctly deleted.

Misc

• The unreachable_code lint warns when a function call's argument diverges.
• The parser indicates failures that may be caused by confusingly-similar Unicode characters
• Certain macro errors are reported at definition time, not expansion.

Compatibility Notes

• The compiler no longer makes use of the RUST_PATH environment variable when locating crates. This was a pre-cargo feature for integrating with the package manager that was accidentally never removed.
• A number of bugs were fixed in the privacy checker that could cause previously-accepted code to break.
• Modules and unit/tuple structs may not share the same name.
• Bugs in pattern matching unit structs were fixed. The tuple struct pattern syntax (Foo(..)) can no longer be used to match unit structs. This is a warning now, but will become an error in future releases. Patterns that share the same name as a const are now an error.
• A bug was fixed that causes rustc not to apply default type parameters when resolving certain method implementations of traits defined in other crates.

Rust 1.5.0

• ~700 changes, numerous bugfixes

Highlights

• Stabilized APIs: BinaryHeap::from, BinaryHeap::into_sorted_vec, BinaryHeap::into_vec, Condvar::wait_timeout, FileTypeExt::is_block_device, FileTypeExt::is_char_device, FileTypeExt::is_fifo, FileTypeExt::is_socket, FileTypeExt, Formatter::alternate, Formatter::fill, Formatter::precision, Formatter::sign_aware_zero_pad, Formatter::sign_minus, Formatter::sign_plus, Formatter::width, Iterator::cmp, Iterator::eq, Iterator::ge, Iterator::gt, Iterator::le, Iterator::lt, Iterator::ne, Iterator::partial_cmp, Path::canonicalize, Path::exists, Path::is_dir, Path::is_file, Path::metadata, Path::read_dir, Path::read_link, Path::symlink_metadata, Utf8Error::valid_up_to, Vec::resize, VecDeque::as_mut_slices, VecDeque::as_slices, VecDeque::insert, VecDeque::shrink_to_fit, VecDeque::swap_remove_back, VecDeque::swap_remove_front, slice::split_first_mut, slice::split_first, slice::split_last_mut, slice::split_last, char::from_u32_unchecked, fs::canonicalize, str::MatchIndices, str::RMatchIndices, str::match_indices, str::rmatch_indices, str::slice_mut_unchecked, string::ParseError.
• Rust applications hosted on crates.io can be installed locally to ~/.cargo/bin with the cargo install command. Among other things this makes it easier to augment Cargo with new subcommands: when a binary named e.g. cargo-foo is found in $PATH it can be invoked as cargo foo.
• Crates with wildcard (*) dependencies will emit warnings when published. In 1.6 it will no longer be possible to publish crates with wildcard dependencies.

Breaking Changes

• The rules determining when a particular lifetime must outlive a particular value (known as 'dropck') have been modified to not rely on parametricity.
• Implementations of AsRef and AsMut were added to Box, Rc, and Arc. Because these smart pointer types implement Deref, this causes breakage in cases where the interior type contains methods of the same name.
• Correct a bug in Rc/Arc that caused dropck to be unaware that they could drop their content. Soundness fix.
• All method invocations are properly checked for well-formedness. Soundness fix.
• Traits whose supertraits contain Self are not object safe. Soundness fix.
• Target specifications support a no_default_libraries setting that controls whether -nodefaultlibs is passed to the linker, and in turn the is_like_windows setting no longer affects the -nodefaultlibs flag.
• #[derive(Show)], long-deprecated, has been removed.
• The #[inline] and #[repr] attributes can only appear in valid locations.
• Native libraries linked from the local crate are passed to the linker before native libraries from upstream crates.
• Two rarely-used attributes, #[no_debug] and #[omit_gdb_pretty_printer_section] are feature gated.
• Negation of unsigned integers, which has been a warning for several releases, is now behind a feature gate and will generate errors.
• The parser accidentally accepted visibility modifiers on enum variants, a bug which has been fixed.
• A bug was fixed that allowed use statements to import unstable features.

Language

• When evaluating expressions at compile-time that are not compile-time constants (const-evaluating expressions in non-const contexts), incorrect code such as overlong bitshifts and arithmetic overflow will generate a warning instead of an error, delaying the error until runtime. This will allow the const-evaluator to be expanded in the future backwards-compatibly.
• The improper_ctypes lint no longer warns about using isize and usize in FFI.

Libraries

• Arc<T> and Rc<T> are covariant with respect to T instead of invariant.
• Default is implemented for mutable slices.
• FromStr is implemented for SockAddrV4 and SockAddrV6.
• There are now From conversions between floating point types where the conversions are lossless.
• There are now From conversions between integer types where the conversions are lossless.
• fs::Metadata implements Clone.
• The parse method accepts a leading "+" when parsing integers.
• [AsMut is implement...