Rust 1.16.0

Language

• The compiler's dead_code lint now accounts for type aliases.
• Uninhabitable enums (those without any variants) no longer permit wildcard match patterns
• Clean up semantics of self in an import list
• Self may appear in impl headers
• Self may appear in struct expressions

Compiler

• rustc now supports --emit=metadata, which causes rustc to emit a .rmeta file containing only crate metadata. This can be used by tools like the Rust Language Service to perform metadata-only builds.
• Levenshtein based typo suggestions now work in most places, while previously they worked only for fields and sometimes for local variables. Together with the overhaul of "no resolution"/"unexpected resolution" errors (#38154) they result in large and systematic improvement in resolution diagnostics.
• Fix transmute::<T, U> where T requires a bigger alignment than U
• rustc: use -Xlinker when specifying an rpath with ',' in it
• rustc no longer attempts to provide "consider using an explicit lifetime" suggestions. They were inaccurate.

Stabilized APIs

• VecDeque::truncate
• VecDeque::resize
• String::insert_str
• Duration::checked_add
• Duration::checked_sub
• Duration::checked_div
• Duration::checked_mul
• str::replacen
• str::repeat
• SocketAddr::is_ipv4
• SocketAddr::is_ipv6
• IpAddr::is_ipv4
• IpAddr::is_ipv6
• Vec::dedup_by
• Vec::dedup_by_key
• Result::unwrap_or_default
• <*const T>::wrapping_offset
• <*mut T>::wrapping_offset
• CommandExt::creation_flags
• File::set_permissions
• String::split_off

Libraries

• [T]::binary_search and [T]::binary_search_by_key now take their argument by Borrow parameter
• All public types in std implement Debug
• IpAddr implements From<Ipv4Addr> and From<Ipv6Addr>
• Ipv6Addr implements From<[u16; 8]>
• Ctrl-Z returns from Stdin.read() when reading from the console on Windows
• std: Fix partial writes in LineWriter
• std: Clamp max read/write sizes on Unix
• Use more specific panic message for &str slicing errors
• TcpListener::set_only_v6 is deprecated. This functionality cannot be achieved in std currently.
• writeln!, like println!, now accepts a form with no string or formatting arguments, to just print a newline
• Implement iter::Sum and iter::Product for Result
• Reduce the size of static data in std_unicode::tables
• char::EscapeDebug, EscapeDefault, EscapeUnicode, CaseMappingIter, ToLowercase, ToUppercase, implement Display
• Duration implements Sum
• String implements ToSocketAddrs

Cargo

• The cargo check command does a type check of a project without building it
• crates.io will display CI badges from Travis and AppVeyor, if specified in Cargo.toml
• crates.io will display categories listed in Cargo.toml
• Compilation profiles accept integer values for debug, in addition to true and false. These are passed to rustc as the value to -C debuginfo
• Implement cargo --version --verbose
• All builds now output 'dep-info' build dependencies compatible with make and ninja
• Build all workspace members with build --all
• Document all workspace members with doc --all
• Path deps outside workspace are not members

Misc

• rustdoc has a --sysroot argument that, like rustc, specifies the path to the Rust implementation
• The armv7-linux-androideabi target no longer enables NEON extensions, per Google's ABI guide
• The stock standard library can be compiled for Redox OS
• Rust has initial SPARC support. Tier 3. No builds available.
• Rust has experimental support for Nvidia PTX. Tier 3. No builds available.
• Fix backtraces on i686-pc-windows-gnu by disabling FPO

Compatibility Notes

• Uninhabitable enums (those without any variants) no longer permit wildcard match patterns
• In this release, references to uninhabited types can not be pattern-matched. This was accidentally allowed in 1.15.
• The compiler's dead_code lint now accounts for type aliases.
• Ctrl-Z returns from Stdin.read() when reading from the console on Windows
• Clean up semantics of self in an import list
• Reimplemented lifetime elision. This change was almost entirely compatible with existing code, but it did close a number of small bugs and loopholes, as well as being more accepting in some other cases.