Rust release · Mar 16, 2017

Rust 1.16: what's new, what was stabilized

Short answerRust 1.16 was released on Mar 16, 2017: 21 newly stable APIs (VecDeque::truncate, VecDeque::resize, String::insert_str, Duration::checked_add, ...); 6 compatibility notes that can affect existing code.

Mar 16, 2017release date

0language stabilizations

21APIs stabilized

-new edition

← Rust 1.15 All versions Rust 1.17 →

21 APIs stabilized

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

Can it break my build?

The release lists these compatibility notes. Most only affect rare code, but read them before you raise your toolchain in CI:

[Uninhabitable enums (those without any variants) no longer permit wildcard
In this release, references to uninhabited types can not be
[The compiler's dead_code lint now accounts for type aliases][38051].
[Ctrl-Z returns from Stdin.read() when reading from the console on
[Clean up semantics of self in an import list][38313]
Reimplemented lifetime elision. This change was almost entirely compatible

Use it

rustup update stable        # get the newest release
rustup install 1.16          # or exactly this one
rustup override set 1.16     # pin a project to it

To require at least this version from users of your crate, set rust-version = "1.16" under [package] in Cargo.toml. Cargo then refuses to build it on older compilers with a clear message, and with resolver 3 (the default on the 2024 edition, Rust 1.85+) it also prefers dependency versions that support it.

Full release notes

Language

[The compiler's dead_code lint now accounts for type aliases][38051].
[Uninhabitable enums (those without any variants) no longer permit wildcard match patterns][38069]
[Clean up semantics of self in an import list][38313]
[Self may appear in impl headers][38920]
[Self may appear in struct expressions][39282]

Compiler

[rustc now supports --emit=metadata, which causes rustc to emit a .rmeta file containing only crate metadata][38571]. 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][38927]. 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][38670]
[rustc: use -Xlinker when specifying an rpath with ',' in it][38798]
[rustc no longer attempts to provide "consider using an explicit lifetime" suggestions][37057]. 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][37761]
[All public types in std implement Debug][38006]
[IpAddr implements From<Ipv4Addr> and From<Ipv6Addr>][38327]
[Ipv6Addr implements From<[u16; 8]>][38131]
[Ctrl-Z returns from Stdin.read() when reading from the console on Windows][38274]
[std: Fix partial writes in LineWriter][38062]
[std: Clamp max read/write sizes on Unix][38622]
[Use more specific panic message for &str slicing errors][38066]
[TcpListener::set_only_v6 is deprecated][38304]. 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][38469]
[Implement iter::Sum and iter::Product for Result][38580]
[Reduce the size of static data in std_unicode::tables][38781]
[char::EscapeDebug, EscapeDefault, EscapeUnicode, CaseMappingIter, ToLowercase, ToUppercase, implement Display][38909]
[Duration implements Sum][38712]
[String implements ToSocketAddrs][39048]

Cargo

[The cargo check command does a type check of a project without building it][cargo/3296]
[crates.io will display CI badges from Travis and AppVeyor, if specified in Cargo.toml][cargo/3546]
[crates.io will display categories listed in Cargo.toml][cargo/3301]
[Compilation profiles accept integer values for debug, in addition to true and false. These are passed to rustc as the value to -C debuginfo][cargo/3534]
[Implement cargo --version --verbose][cargo/3604]
[All builds now output 'dep-info' build dependencies compatible with make and ninja][cargo/3557]
[Build all workspace members with build --all][cargo/3511]
[Document all workspace members with doc --all][cargo/3515]
[Path deps outside workspace are not members][cargo/3443]

Misc

[rustdoc has a --sysroot argument that, like rustc, specifies the path to the Rust implementation][38589]
[The armv7-linux-androideabi target no longer enables NEON extensions, per Google's ABI guide][38413]
[The stock standard library can be compiled for Redox OS][38401]
[Rust has initial SPARC support][38726]. Tier 3. No builds available.
[Rust has experimental support for Nvidia PTX][38559]. Tier 3. No builds available.
[Fix backtraces on i686-pc-windows-gnu by disabling FPO][39379]

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.

Release notes from the Rust project's RELEASES.md (MIT or Apache-2.0); summaries above are ours.