Releases: rust-lang/rust
Releases · rust-lang/rust
Rust 1.7.0
Libraries
- Stabilized APIs
PathPath::strip_prefix(renamed from relative_from)path::StripPrefixError(new error type returned from strip_prefix)
Ipv4AddrIpv6AddrVecString- 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_shri32::saturating_muli32::overflowing_add,i32::overflowing_sub,i32::overflowing_mul,i32::overflowing_divi32::overflowing_rem,i32::overflowing_neg,i32::overflowing_shl,i32::overflowing_shru32::checked_rem,u32::checked_neg,u32::checked_shl,u32::checked_shlu32::saturating_mulu32::overflowing_add,u32::overflowing_sub,u32::overflowing_mul,u32::overflowing_divu32::overflowing_rem,u32::overflowing_neg,u32::overflowing_shl,u32::overflowing_shr- and checked, saturated, and overflowing operations for other primitive types
- FFI
ffi::IntoStringErrorCString::into_stringCString::into_bytesCString::into_bytes_with_nulFrom<CString> for Vec<u8>
IntoStringErrorIntoStringError::into_cstringIntoStringError::utf8_errorError for IntoStringError
- Hashing
- Validating UTF-8 is faster by a factor of between 7 and 14x for ASCII input. This means that creating
Strings andstrs from bytes is faster. - The performance of
LineWriter(and thusio::stdout) was improved by usingmemchrto search for newlines. f32::to_degreesandf32::to_radiansare stable. Thef64variants were stabilized previously.BTreeMapwas rewritten to use less memory and improve the performance of insertion and iteration, the latter by as much as 5x.BTreeSetand its iterators,Iter,IntoIter, andRangeare covariant over their contained type.LinkedListand its iterators,IterandIntoIterare covariant over their contained type.str::replacenow accepts aPattern, like other string searching methods.Anyis implemented for unsized types.Hashis implemented forDuration.
Misc
- When running tests with
--test, rustdoc will pass--cfgarguments to the compiler. - The compiler is built with RPATH information by default. This means that it will be possible to run
rustcwhen installed in unusual configurations without configuring the dynamic linker search path explicitly. rustcpasses--enable-new-dtagsto GNU ld. This makes any RPATH entries (emitted with-C rpath) not take precedence overLD_LIBRARY_PATH.
Cargo
cargo rustcaccepts a--profileflag that runsrustcunder any of the compilation profiles, 'dev', 'bench', or 'test'.- The
rerun-if-changedbuild 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 fromUnexpectedEOF),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 frompush_all),Mutex::get_mut,Mutex::into_inner,RwLock::get_mut,RwLock::into_inner,Iterator::min_by_key(renamed frommin_by),Iterator::max_by_key(renamed frommax_by). - The core library is stable, as are most of its APIs.
- The
assert_eq!macro supports arguments that don't implementSized, such as arrays. In this way it behaves more likeassert!. - Several timer functions that take duration in milliseconds are deprecated in favor of those that take
Duration. These includeCondvar::wait_timeout_ms,thread::sleep_ms, andthread::park_timeout_ms. - The algorithm by which
Vecreserves additional elements was tweaked to not allocate excessive space while still growing exponentially. Fromconversions are implemented from integers to floats in cases where the conversion is lossless. Thus they are not implemented for 32-bit ints tof32, nor for 64-bit ints tof32orf64. They are also not implemented forisizeandusizebecause the implementations would be platform-specific.Fromis also implemented fromf32tof64.From<&Path>andFrom<PathBuf>are implemented forCow<Path>.From<T>is implemented forBox<T>,Rc<T>andArc<T>.IntoIteratoris implemented for&PathBufand&Path.BinaryHeapwas refactored for modest performance improvements.- Sorting slices that are already sorted is 50% faster in some cases.
Cargo
- Cargo will look in
$CARGO_HOME/binfor subcommands by default. - Cargo build scripts can specify their dependencies by emitting the
rerun-if-changedkey. - 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 cleanaccepts a--releaseflag to clean the release folder. A variety of artifacts that Cargo failed to clean are now correctly deleted.
Misc
- The
unreachable_codelint 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_PATHenvironment 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/binwith thecargo installcommand. Among other things this makes it easier to augment Cargo with new subcommands: when a binary named e.g.cargo-foois found in$PATHit can be invoked ascargo 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
AsRefandAsMutwere added toBox,Rc, andArc. Because these smart pointer types implementDeref, 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
Selfare not object safe. Soundness fix. - Target specifications support a
no_default_librariessetting that controls whether-nodefaultlibsis passed to the linker, and in turn theis_like_windowssetting no longer affects the-nodefaultlibsflag. #[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
usestatements 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_ctypeslint no longer warns about usingisizeandusizein FFI.
Libraries
Arc<T>andRc<T>are covariant with respect toTinstead of invariant.Defaultis implemented for mutable slices.FromStris implemented forSockAddrV4andSockAddrV6.- There are now
Fromconversions between floating point types where the conversions are lossless. - There are now
Fromconversions between integer types where the conversions are lossless. fs::MetadataimplementsClone.- The
parsemethod accepts a leading "+" when parsing integers. - [
AsMutis implement...
Rust 1.4.0
- ~1200 changes, numerous bugfixes
Highlights
- Windows builds targeting the 64-bit MSVC ABI and linker (instead of GNU) are now supported and recommended for use.
Breaking Changes
- Several changes have been made to fix type soundness and improve the behavior of associated types. See RFC 1214. Although we have mostly introduced these changes as warnings this release, to become errors next release, there are still some scenarios that will see immediate breakage.
- The
str::linesandBufRead::linesiterators treat\r\nas line breaks in addition to\n. - Loans of
'staticlifetime extend to the end of a function. str::parseno longer introduces avoidable rounding error when parsing floating point numbers. Together with earlier changes to float formatting/output, "round trips" like f.to_string().parse() now preserve the value of f exactly. Additionally, leading plus signs are now accepted.
Language
usestatements that import multiple items can now rename them, as inuse foo::{bar as kitten, baz as puppy}.- Binops work correctly on fat pointers.
pub extern crate, which does not behave as expected, issues a warning until a better solution is found.
Libraries
- Many APIs were stabilized:
<Box<str>>::into_string,Arc::downgrade,Arc::get_mut,Arc::make_mut,Arc::try_unwrap,Box::from_raw,Box::into_raw,CStr::to_str,CStr::to_string_lossy,CString::from_raw,CString::into_raw,IntoRawFd::into_raw_fd,IntoRawFd,IntoRawHandle::into_raw_handle,IntoRawHandle,IntoRawSocket::into_raw_socket,IntoRawSocket,Rc::downgrade,Rc::get_mut,Rc::make_mut,Rc::try_unwrap,Result::expect,String::into_boxed_str,TcpStream::read_timeout,TcpStream::set_read_timeout,TcpStream::set_write_timeout,TcpStream::write_timeout,UdpSocket::read_timeout,UdpSocket::set_read_timeout,UdpSocket::set_write_timeout,UdpSocket::write_timeout,Vec::append,Vec::split_off,VecDeque::append,VecDeque::retain,VecDeque::split_off,rc::Weak::upgrade,rc::Weak,slice::Iter::as_slice,slice::IterMut::into_slice,str::CharIndices::as_str,str::Chars::as_str,str::split_at_mut,str::split_at,sync::Weak::upgrade,sync::Weak,thread::park_timeout,thread::sleep. - Some APIs were deprecated:
BTreeMap::with_b,BTreeSet::with_b,Option::as_mut_slice,Option::as_slice,Result::as_mut_slice,Result::as_slice,f32::from_str_radix,f64::from_str_radix. - Reverse-searching strings is faster with the 'two-way' algorithm.
std::io::copyallows?Sizedarguments.- The
Windows,Chunks, andChunksMutiterators over slices all overridecount,nthandlastwith an O(1) implementation. Defaultis implemented for arrays up to[T; 32].IntoRawFdhas been added to the Unix-specific prelude,IntoRawSocketandIntoRawHandleto the Windows-specific prelude.Extend<String>andFromIterator<Stringare both implemented forString.IntoIteratoris implemented for references toOptionandResult.HashMapandHashSetimplementExtend<&T>whereT: Copyas part of RFC 839. This will cause type inference breakage in rare situations.BinaryHeapimplementsDebug.BorrowandBorrowMutare implemented for fixed-size arrays.extern fns with the "Rust" and "C" ABIs implement common traits includingEq,Ord,Debug,Hash.- String comparison is faster.
&mut TwhereT: std::fmt::Writealso implementsstd::fmt::Write.- A stable regression in
VecDeque::push_backand other capacity-altering methods that caused panics for zero-sized types was fixed. - Function pointers implement traits for up to 12 parameters.
Miscellaneous
- The compiler no longer uses the 'morestack' feature to prevent stack overflow. Instead it uses guard pages and stack probes (though stack probes are not yet implemented on any platform but Windows).
- The compiler matches traits faster when projections are involved.
- The 'improper_ctypes' lint no longer warns about use of
isizeandusize. - Cargo now displays useful information about what its doing during
cargo update.
Rust 1.3.0
- ~900 changes, numerous bugfixes
Highlights
- The new object lifetime defaults have been turned on after a cycle of warnings about the change. Now types like
&'a Box<Trait>(or&'a Rc<Trait>, etc) will change from being interpreted as&'a Box<Trait+'a>to&'a Box<Trait+'static>. - The Rustonomicon is a new book in the official documentation that dives into writing unsafe Rust.
- The
DurationAPI, has been stabilized. This basic unit of timekeeping is employed by other std APIs, as well as out-of-tree time crates.
Breaking Changes
- The new object lifetime defaults have been turned on after a cycle of warnings about the change.
- There is a known regression in how object lifetime elision is interpreted, the proper solution for which is undetermined.
- The
#[prelude_import]attribute, an internal implementation detail, was accidentally stabilized previously. It has been put behind theprelude_importfeature gate. This change is believed to break no existing code. - The behavior of
size_of_valandalign_of_valis more sane for dynamically sized types. Code that relied on the previous behavior is thought to be broken. - The
dropckrules, which checks that destructors can't access destroyed values, have been updated to match the RFC. This fixes some soundness holes, and as such will cause some previously-compiling code to no longer build.
Language
- The new object lifetime defaults have been turned on after a cycle of warnings about the change.
- Semicolons may now follow types and paths in macros.
- The behavior of
size_of_valandalign_of_valis more sane for dynamically sized types. Code that relied on the previous behavior is not known to exist, and suspected to be broken. 'staticvariables may now be recursive.refbindings choose betweenDerefandDerefMutimplementations correctly.- The
dropckrules, which checks that destructors can't access destroyed values, have been updated to match the RFC.
Libraries
- The
DurationAPI, has been stabilized, as well as thestd::timemodule, which presently contains onlyDuration. Box<str>andBox<[T]>both implementClone.- The owned C string,
CString, implementsBorrowand the borrowed C string,CStr, implementsToOwned. The two of these allow C strings to be borrowed and cloned in generic code. CStrimplementsDebug.AtomicPtrimplementsDebug.Errortrait objects can be downcast to their concrete types in many common configurations, using theis,downcast,downcast_refanddowncast_mutmethods, similarly to theAnytrait.- Searching for substrings now employs the two-way algorithm instead of doing a naive search. This gives major speedups to a number of methods, including
contains,find,rfind,split.starts_withandends_withare also faster. - The performance of
PartialEqfor slices is much faster. - The
Hashtrait offers the default method,hash_slice, which is overridden and optimized by the implementations for scalars. - The
Hashertrait now has a number of specializedwrite_*methods for primitive types, for efficiency. - The I/O-specific error type,
std::io::Error, gained a set of methods for accessing the 'inner error', if any:get_ref,get_mut,into_inner. As well, the implementation ofstd::error::Error::causealso delegates to the inner error. process::Childgained theidmethod, which returns au32representing the platform-specific process identifier.- The
connectmethod on slices is deprecated, replaced by the newjoinmethod (note that both of these are on the unstableSliceConcatExttrait, but through the magic of the prelude are available to stable code anyway). - The
Divoperator is implemented forWrappingtypes. DerefMutis implemented forString.- Performance of SipHash (the default hasher for
HashMap) is better for long data. AtomicPtrimplementsSend.- The
read_to_endimplementations forStdinandFileare now specialized to use uninitialized buffers for increased performance. - Lifetime parameters of foreign functions are now resolved properly.
Misc
- Rust can now, with some coercion, produce programs that run on Windows XP, though XP is not considered a supported platform.
- Porting Rust on Windows from the GNU toolchain to MSVC continues (1, 2, 3, 4). It is still not recommended for use in 1.3, though should be fully-functional in the 64-bit 1.4 beta.
- On Fedora-based systems installation will properly configure the dynamic linker.
- The compiler gained many new extended error descriptions, which can be accessed with the
--explainflag. - The
dropckpass, which checks that destructors can't access destroyed values, has been rewritten. This fixes ...
Rust 1.2.0
- ~1200 changes, numerous bugfixes
Highlights
- Dynamically-sized-type coercions allow smart pointer types like
Rcto contain types without a fixed size, arrays and trait objects, finally enabling use ofRc<[T]>and completing the implementation of DST. - Parallel codegen is now working again, which can substantially speed up large builds in debug mode; It also gets another ~33% speedup when bootstrapping on a 4 core machine (using 8 jobs). It's not enabled by default, but will be "in the near future". It can be activated with the
-C codegen-units=Nflag torustc. - This is the first release with experimental support for linking with the MSVC linker and lib C on Windows (instead of using the GNU variants via MinGW). It is yet recommended only for the most intrepid Rustaceans.
- Benchmark compilations are showing a 30% improvement in bootstrapping over 1.1.
Breaking Changes
- The
to_uppercaseandto_lowercasemethods oncharnow do unicode case mapping, which is a previously-planned change in behavior and considered a bugfix. mem::align_ofnow specifies the minimum alignment for T, which is usually the alignment programs are interested in, and the same value reported by clang'salignof.mem::min_align_ofis deprecated. This is not known to break real code.- The
#[packed]attribute is no longer silently accepted by the compiler. This attribute did nothing and code that mentioned it likely did not work as intended. - Associated type defaults are now behind the
associated_type_defaultsfeature gate. In 1.1 associated type defaults did not work, but could be mentioned syntactically. As such this breakage has minimal impact.
Language
- Patterns with
ref mutnow correctly invokeDerefMutwhen matching against dereferenceable values.
Libraries
- The
Extendtrait, which grows a collection from an iterator, is implemented over iterators of references, forString,Vec,LinkedList,VecDeque,EnumSet,BinaryHeap,VecMap,BTreeSetandBTreeMap. RFC. - The
iter::oncefunction returns an iterator that yields a single element, anditer::emptyreturns an iterator that yields no elements. - The
matchesandrmatchesmethods onstrreturn iterators over substring matches. CellandRefCellboth implementEq.- A number of methods for wrapping arithmetic are added to the integral types,
wrapping_div,wrapping_rem,wrapping_neg,wrapping_shl,wrapping_shr. These are in addition to the existingwrapping_add,wrapping_sub, andwrapping_mulmethods, and alternatives to theWrappingtype.. It is illegal for the default arithmetic operations in Rust to overflow; the desire to wrap must be explicit. - The
{:#?}formatting specifier displays the alternate, pretty-printed form of theDebugformatter. This feature was actually introduced prior to 1.0 with little fanfare. fmt::Formatterimplementsfmt::Write, afmt-specific trait for writing data to formatted strings, similar toio::Write.fmt::Formatteradds 'debug builder' methods,debug_struct,debug_tuple,debug_list,debug_set,debug_map. These are used by code generators to emit implementations ofDebug.strhas newto_uppercaseandto_lowercasemethods that convert case, following Unicode case mapping.- It is now easier to handle poisoned locks. The
PoisonErrortype, returned by failing lock operations, exposesinto_inner,get_ref, andget_mut, which all give access to the inner lock guard, and allow the poisoned lock to continue to operate. Theis_poisonedmethod ofRwLockandMutexcan poll for a poisoned lock without attempting to take the lock. - On Unix the
FromRawFdtrait is implemented forStdio, andAsRawFdforChildStdin,ChildStdout,ChildStderr. On Windows theFromRawHandletrait is implemented forStdio, andAsRawHandleforChildStdin,ChildStdout,ChildStderr. io::ErrorKindhas a new variant,InvalidData, which indicates malformed input.
Misc
rustcemploys smarter heuristics for guessing at typos.rustcemits more efficient code for no-op conversions between unsafe pointers.- Fat pointers are now passed in pairs of immediate arguments, resulting in faster compile times and smaller code.
Rust 1.1.0
- ~850 changes, numerous bugfixes
Highlights
- The
std::fsmodule has been expanded to expand the set of functionality exposed:DirEntrynow supports optimizations likefile_typeandmetadatawhich don't incur a syscall on some platforms.- A
symlink_metadatafunction has been added. - The
fs::Metadatastructure now lowers to its OS counterpart, providing access to all underlying information.
- The compiler now contains extended explanations of many errors. When an error with an explanation occurs the compiler suggests using the
--explainflag to read the explanation. Error explanations are also available online. - Thanks to multiple improvements to type checking, as well as other work, the time to bootstrap the compiler decreased by 32%.
Libraries
- The
str::split_whitespacemethod splits a string on unicode whitespace boundaries. - On both Windows and Unix, new extension traits provide conversion of I/O types to and from the underlying system handles. On Unix, these traits are
FromRawFdandAsRawFd, on WindowsFromRawHandleandAsRawHandle. These are implemented forFile,TcpStream,TcpListener, andUpdSocket. Further implementations forstd::processwill be stabilized later. - On Unix,
std::os::unix::symlinkcreates symlinks. On Windows, symlinks can be created withstd::os::windows::symlink_dirandstd::os::windows::symlink_file. - The
mpsc::Receivertype can now be converted into an iterator withinto_iteron theIntoIteratortrait. Ipv4Addrcan be created fromu32with theFrom<u32>implementation of theFromtrait.- The
Debugimplementation forRangeFullcreates output that is more consistent with other implementations. Debugis implemented forFile.- The
Defaultimplementation forArcno longer requiresSync + Send. - The
Iteratormethodscount,nth, andlasthave been overridden for slices to have O(1) performance instead of O(n). - Incorrect handling of paths on Windows has been improved in both the compiler and the standard library.
AtomicPtrgained aDefaultimplementation.- In accordance with Rust's policy on arithmetic overflow
absnow panics on overflow when debug assertions are enabled. - The
Clonediterator, which was accidentally left unstable for 1.0 has been stabilized. - The
Incomingiterator, which iterates over incoming TCP connections, and which was accidentally unnamable in 1.0, is now properly exported. BinaryHeapno longer corrupts itself when functions called bysift_uporsift_downpanic.- The
split_offmethod ofLinkedListno longer corrupts the list in certain scenarios.
Misc
- Type checking performance has improved notably with multiple improvements.
- The compiler suggests code changes for more errors.
- rustc and it's build system have experimental support for building toolchains against MUSL instead of glibc on Linux.
- The compiler defines the
target_envcfg value, which is used for distinguishing toolchains that are otherwise for the same platform. Presently this is set tognufor common GNU Linux targets and for MinGW targets, andmuslfor MUSL Linux targets. - The
cargo rustccommand invokes a build with custom flags to rustc. - Android executables are always position independent.
- The
drop_with_repr_externlint warns about mixingrepr(C)withDrop.
Rust 1.0.0
- ~1500 changes, numerous bugfixes
Highlights
- The vast majority of the standard library is now
#[stable]. It is no longer possible to use unstable features with a stable build of the compiler. - Many popular crates on crates.io now work on the stable release channel.
- Arithmetic on basic integer types now checks for overflow in debug builds.
Language
- Several restrictions have been added to trait coherence in order to make it easier for upstream authors to change traits without breaking downstream code.
- Digits of binary and octal literals are lexed more eagerly to improve error messages and macro behavior. For example,
0b1234is now lexed as0b1234instead of two tokens,0b1and234. - Trait bounds are always invariant, eliminating the need for the
PhantomFnandMarkerTraitlang items, which have been removed. - "-" is no longer a valid character in crate names, the
extern crate "foo" as barsyntax has been replaced withextern crate foo as bar, and Cargo now automatically translates "-" in package names to underscore for the crate name. - Lifetime shadowing is an error.
Sendno longer implies'static.- UFCS now supports trait-less associated paths like
MyType::default(). - Primitive types now have inherent methods, obviating the need for extension traits like
SliceExt. - Methods with
Self: Sizedin theirwhereclause are considered object-safe, allowing many extension traits likeIteratorExtto be merged into the traits they extended. - You can now refer to associated types whose corresponding trait bounds appear only in a
whereclause. - The final bits of OIBIT landed, meaning that traits like
SendandSyncare now library-defined. - A Reflect trait was introduced, which means that downcasting via the
Anytrait is effectively limited to concrete types. This helps retain the potentially-important "parametricity" property: generic code cannot behave differently for different type arguments except in minor ways. - The
unsafe_destructorfeature is now deprecated in favor of the newdropck. This change is a major reduction in unsafe code.
Libraries
- The
thread_localmodule has been renamed tostd::thread. - The methods of
IteratorExthave been moved to theIteratortrait itself. - Several traits that implement Rust's conventions for type conversions,
AsMut,AsRef,From, andIntohave been centralized in thestd::convertmodule. - The
FromErrortrait was removed in favor ofFrom. - The basic sleep function has moved to
std::thread::sleep_ms. - The
splitnfunction now takes annparameter that represents the number of items yielded by the returned iterator instead of the number of 'splits'. - On Unix, all file descriptors are
CLOEXECby default. - Derived implementations of
PartialOrdnow order enums according to their explicitly-assigned discriminants. - Methods for searching strings are generic over
Patterns, implemented presently by&char,&str,FnMut(char) -> booland some others. - In method resolution, object methods are resolved before inherent methods.
String::from_strhas been deprecated in favor of theFromimpl,String::from.io::ErrorimplementsSync.- The
wordsmethod on&strhas been replaced withsplit_whitespace, to avoid answering the tricky question, 'what is a word?' - The new path and IO modules are complete and
#[stable]. This was the major library focus for this cycle. - The path API was revised to normalize
., adjusting the tradeoffs in favor of the most common usage. - A large number of remaining APIs in
stdwere also stabilized during this cycle; about 75% of the non-deprecated API surface is now stable. - The new string pattern API landed, which makes the string slice API much more internally consistent and flexible.
- A new set of generic conversion traits replaced many existing ad hoc traits.
- Generic numeric traits were completely removed. This was made possible thanks to inherent methods for primitive types, and the removal gives maximal flexibility for designing a numeric hierarchy in the future.
- The
Fntraits are now related via inheritance and provide ergonomic blanket implementations. - The
IndexandIndexMuttraits were changed to take the index by value, enabling code likehash_map["string"]to work. Copynow inherits fromClone, meaning that allCopydata is known to beCloneas well.
Misc
- Many errors now have extended explanations that can be accessed with the
--explainflag torustc. - Many new examples have been added to the standard library documentation.
- rustdoc has received a number of improvements focused on completion and polish.
- Metadata was tuned, shrinking binaries by 27%.
- Much headway was made on ecosystem-wide CI, making it possible to compare builds for breakage.
Rust 1.0.0-alpha.2
-
~1300 changes, numerous bugfixes
-
Highlights
- The various I/O modules were overhauled to reduce unnecessary abstractions and provide better interoperation with the underlying platform. The old
iomodule remains temporarily atstd::old_io. - The standard library now participates in feature gating, so use of unstable libraries now requires a
#![feature(...)]attribute. The impact of this change is described on the forum. RFC.
- The various I/O modules were overhauled to reduce unnecessary abstractions and provide better interoperation with the underlying platform. The old
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Language
forloops now operate on theIntoIteratortrait, which eliminates the need to call.iter(), etc. to iterate over collections. There are some new subtleties to remember though regarding what sort of iterators various types yield, in particular thatfor foo in bar { }yields values from a move iterator, destroying the original collection. RFC.- Objects now have default lifetime bounds, so you don't have to write
Box<Trait+'static>when you don't care about storing references. RFC. - In types that implement
Drop, lifetimes must outlive the value. This will soon make it possible to safely implementDropfor types where#[unsafe_destructor]is now required. Read the gorgeous RFC for details. - The fully qualified ::X syntax lets you set the Self type for a trait method or associated type. RFC.
- References to types that implement
Deref<U>now automatically coerce to references to the dereferenced typeU, e.g.&T where T: Deref<U>automatically coerces to&U. This should eliminate many unsightly uses of&*, as when converting from references to vectors into references to slices. RFC. - The explicit closure kind syntax (
|&:|,|&mut:|,|:|) is obsolete and closure kind is inferred from context. Selfis a keyword.
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Libraries
- The
ShowandStringformatting traits have been renamed toDebugandDisplayto more clearly reflect their related purposes. Automatically getting a string conversion to use withformat!("{:?}", something_to_debug)is now written#[derive(Debug)]. - Abstract OS-specific string types,
std::ff::{OsString, OsStr}, provide strings in platform-specific encodings for easier interop with system APIs. RFC. - The
boxed::into_rawandBox::from_rawfunctions convert betweenBox<T>and*mut T, a common pattern for creating raw pointers.
- The
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Tooling
- Certain long error messages of the form 'expected foo found bar' are now split neatly across multiple lines. Examples in the PR.
- On Unix Rust can be uninstalled by running
/usr/local/lib/rustlib/uninstall.sh. - The
#[rustc_on_unimplemented]attribute, requiring the 'on_unimplemented' feature, lets rustc display custom error messages when a trait is expected to be implemented for a type but is not.
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Misc
- Rust is tested against a LALR grammar, which parses almost all the Rust files that rustc does.
Rust 1.0.0-alpha
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~2400 changes, numerous bugfixes
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Highlights
- The language itself is considered feature complete for 1.0, though there will be many usability improvements and bugfixes before the final release.
- Nearly 50% of the public API surface of the standard library has been declared 'stable'. Those interfaces are unlikely to change before 1.0.
- The long-running debate over integer types has been settled: Rust will ship with types named
isizeandusize, rather thanintanduint, for pointer-sized integers. Guidelines will be rolled out during the alpha cycle. - Most crates that are not
stdhave been moved out of the Rust distribution into the Cargo ecosystem so they can evolve separately and don't need to be stabilized as quickly, including 'time', 'getopts', 'num', 'regex', and 'term'. - Documentation continues to be expanded with more API coverage, more examples, and more in-depth explanations. The guides have been consolidated into The Rust Programming Language.
- "Rust By Example" is now maintained by the Rust team.
- All official Rust binary installers now come with Cargo, the Rust package manager.
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Language
- Closures have been completely redesigned to be implemented in terms of traits, can now be used as generic type bounds and thus monomorphized and inlined, or via an opaque pointer (boxed) as in the old system. The new system is often referred to as 'unboxed' closures.
- Traits now support associated types, allowing families of related types to be defined together and used generically in powerful ways.
- Enum variants are namespaced by their type names.
whereclauses provide a more versatile and attractive syntax for specifying generic bounds, though the previous syntax remains valid.- Rust again picks a fallback (either i32 or f64) for uninferred numeric types.
- Rust no longer has a runtime of any description, and only supports OS threads, not green threads.
- At long last, Rust has been overhauled for 'dynamically-sized types' (DST), which integrates 'fat pointers' (object types, arrays, and
str) more deeply into the type system, making it more consistent. - Rust now has a general range syntax,
i..j,i.., and..jthat produce range types and which, when combined with theIndexoperator and multidispatch, leads to a convenient slice notation,[i..j]. - The new range syntax revealed an ambiguity in the fixed-length array syntax, so now fixed length arrays are written
[T; N]. - The
Copytrait is no longer implemented automatically. Unsafe pointers no longer implementSyncandSendso types containing them don't automatically either.SyncandSendare now 'unsafe traits' so one can "forcibly" implement them viaunsafe implif a type confirms to the requirements for them even though the internals do not (e.g. structs containing unsafe pointers likeArc). These changes are intended to prevent some footguns and are collectively known as opt-in built-in traits (thoughSyncandSendwill soon become pure library types unknown to the compiler). - Operator traits now take their operands by value, and comparison traits can use multidispatch to compare one type against multiple other types, allowing e.g.
Stringto be compared with&str. if letandwhile letare no longer feature-gated.- Rust has adopted a more uniform syntax for escaping unicode characters.
macro_rules!has been declared stable. Though it is a flawed system it is sufficiently popular that it must be usable for 1.0. Effort has gone into future-proofing it in ways that will allow other macro systems to be developed in parallel, and won't otherwise impact the evolution of the language.- The prelude has been pared back significantly such that it is the minimum necessary to support the most pervasive code patterns, and through generalized where clauses many of the prelude extension traits have been consolidated.
- Rust's rudimentary reflection has been removed, as it incurred too much code generation for little benefit.
- Struct variants are no longer feature-gated.
- Trait bounds can be polymorphic over lifetimes. Also known as 'higher-ranked trait bounds', this crucially allows unboxed closures to work.
- Macros invocations surrounded by parens or square brackets and not terminated by a semicolon are parsed as expressions, which makes expressions like
vec![1i32, 2, 3].len()work as expected. - Trait objects now implement their traits automatically, and traits that can be coerced to objects now must be object safe.
- Automatically deriving traits is now done with
#[derive(...)]not#[deriving(...)]for consistency with other naming conventions. - Importing the containing module or enum at the same time as items or variants they contain is now done with
selfinstead ofmod, as in usefoo::{self, bar} - Glob imports are no longer feature-gated.
- The
boxoperator andboxpatterns have been feature-gated pending a redesign. For now unique boxes should be allocated like other containers, withBox::new.
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Libraries
- A series of efforts to establish conventions for collections types has resulted in API improvements throughout the standard library.
- New APIs for error handling provide ergonomic interop between error types, and new conventions describe more clearly the recommended error handling strategies in Rust.
- The
fail!macro has been renamed topanic!so that it is easier to discuss failure in the context of error handling without making clarifications as to whether you are referring to the 'fail' macro or failure more generally. - On Linux,
OsRngprefers the new, more reliablegetrandomsyscall when available. - The 'serialize' crate has been renamed 'rustc-serialize' and moved out of the distribution to Cargo. Although it is widely used now, it is expected to be superseded in the near future.
- The
Showformatter, typically implemented with#[derive(Show)]is now requested with the{:?}specifier and is intended for use by all types, for uses such asprintln!debugging. The newStringformatter must be implemented by hand, uses the{}specifier, and is intended for full-fidelity conversions of things that can logically be represented as strings.
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Tooling
- Flexible target specification allows rustc's code generation to be configured to support otherwise-unsupported platforms.
- Rust comes with rust-gdb and rust-lldb scripts that launch their respective debuggers with Rust-appropriate pretty-printing.
- The Windows installation of Rust is distributed with the MinGW components currently required to link binaries on that platform.
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Misc
- Nullable enum optimizations have been extended to more types so that e.g.
Option<Vec<T>>andOption<String>take up no more space than the inner types themselves. - Work has begun on supporting AArch64.
- Nullable enum optimizations have been extended to more types so that e.g.