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.
• Fix #[derive] for empty tuple structs/variants. Part of RFC 1506.
• Issue deprecation warnings for safe accesses to extern statics
• Fix lifetime rules for 'if' conditions.
• Inherit overflow checks for sum and product.
• Forbid user-defined macros named "macro_rules".