Rust 1.3: what's new, what was stabilized

Highlights

• The [new object lifetime defaults][nold] have been [turned on][nold2] 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][nom] is a new book in the official documentation that dives into writing unsafe Rust.
• The [Duration] API, [has been stabilized][ds]. 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][nold] have been [turned on][nold2] after a cycle of warnings about the change.
• There is a known [regression][lr] 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 the prelude_import feature gate][pi]. This change is believed to break no existing code.
• The behavior of [size_of_val][dst1] and [align_of_val][dst2] is [more sane for dynamically sized types][dst3]. Code that relied on the previous behavior is thought to be broken.
• The dropck rules, which checks that destructors can't access destroyed values, [have been updated][dropck] to match the [RFC][dropckrfc]. This fixes some soundness holes, and as such will cause some previously-compiling code to no longer build.

Language

• The [new object lifetime defaults][nold] have been [turned on][nold2] after a cycle of warnings about the change.
• Semicolons may now follow types and paths in macros.
• The behavior of [size_of_val][dst1] and [align_of_val][dst2] is [more sane for dynamically sized types][dst3]. Code that relied on the previous behavior is not known to exist, and suspected to be broken.
• 'static variables [may now be recursive][st].
• ref bindings choose between [Deref] and [DerefMut] implementations correctly.
• The dropck rules, which checks that destructors can't access destroyed values, [have been updated][dropck] to match the [RFC][dropckrfc].

Libraries

• The [Duration] API, [has been stabilized][ds], as well as the std::time module, which presently contains only Duration.
• Box<str> and Box<[T]> both implement Clone.
• The owned C string, [CString], implements [Borrow] and the borrowed C string, [CStr], implements [ToOwned]. The two of these allow C strings to be borrowed and cloned in generic code.
• [CStr] implements [Debug].
• [AtomicPtr] implements [Debug].
• [Error] trait objects [can be downcast to their concrete types][e] in many common configurations, using the [is], [downcast], [downcast_ref] and [downcast_mut] methods, similarly to the [Any] trait.
• Searching for substrings now [employs the two-way algorithm][search] instead of doing a naive search. This gives major speedups to a number of methods, including [contains][sc], [find][sf], [rfind][srf], [split][ss]. [starts_with][ssw] and [ends_with][sew] are also faster.
• The performance of PartialEq for slices is [much faster][ps].
• The [Hash] trait offers the default method, [hash_slice], which is overridden and optimized by the implementations for scalars.
• The [Hasher] trait now has a number of specialized write_* methods for primitive types, for efficiency.
• The I/O-specific error type, [std::io::Error][ie], gained a set of methods for accessing the 'inner error', if any: [get_ref][iegr], [get_mut][iegm], [into_inner][ieii]. As well, the implementation of [std::error::Error::cause][iec] also delegates to the inner error.
• [process::Child][pc] gained the [id] method, which returns a u32 representing the platform-specific process identifier.
• The [connect] method on slices is deprecated, replaced by the new [join] method (note that both of these are on the *unstable* [SliceConcatExt] trait, but through the magic of the prelude are available to stable code anyway).
• The [Div] operator is implemented for [Wrapping] types.
• [DerefMut is implemented for String][dms].
• Performance of SipHash (the default hasher for HashMap) is [better for long data][sh].
• [AtomicPtr] implements [Send].
• The [read_to_end] implementations for [Stdin] and [File] are now [specialized to use uninitialized buffers for increased performance][rte].
• Lifetime parameters of foreign functions [are now resolved properly][f].

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 --explain flag.
• The dropck pass, which checks that destructors can't access destroyed values, has been rewritten. This fixes some soundness holes, and as such will cause some previously-compiling code to no longer build.
• rustc now uses LLVM to write archive files where possible. Eventually this will eliminate the compiler's dependency on the ar utility.
• Rust has preliminary support for i686 FreeBSD (it has long supported FreeBSD on x86_64).
• The unused_mut, unconditional_recursion, improper_ctypes, and negate_unsigned lints are more strict.
• If landing pads are disabled (with -Z no-landing-pads), panic! will kill the process instead of leaking.