1.6 release announcement

Author: steveklabnik

_posts/2016-01-21-Rust-1.6.md

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+---
+layout: post
+title: "Announcing Rust 1.6"
+author: The Rust Core Team
+---
+
+Hello 2016! We’re happy to announce the first Rust release of the year, 1.6.
+Rust is a systems programming language focused on safety, speed, and
+concurrency.
+
+As always, you can [install Rust 1.6][install] from the appropriate page on our
+website, and check out the [detailed release notes for 1.6][notes] on GitHub.
+About 1100 patches were landed in this release.
+
+[install]: http://www.rust-lang.org/install.html
+[notes]: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-160-2016-01-21
+
+### What's in 1.6 stable
+
+This release contains a number of small refinements, one major feature, and
+a change to [Crates.io](https://crates.io).
+
+#### libcore stabilization
+
+The largest new feature in 1.6 is that [`libcore`] is now stable! Rust’s standard
+library is two-tiered: `libcore` contains a lot of functionality, but more important
+is what it does _not_ contain: significant dependencies. `libcore` is completely
+platform agnostic, and requires only a handful of external symbols to be defined.
+Rust’s `libstd` builds on top of `libcore`, adding support for memory allocation,
+I/O, and concurrency. Applications using Rust in the embedded space, as well as
+those writing operating systems, often eschew `libstd`, using only `libcore`.
+
+[`libcore`]: http://doc.rust-lang.org/nightly/core/
+
+`libcore` being stabilized is a major step towards being able to write the lowest
+levels of software using stable Rust. There’s still future work to be done, however,
+so expect to hear more about this in future release notes.
+
+#### Library stabilizations
+
+About 30 library functions and methods are now stable in 1.6. Notable
+improvements include:
+
+The `drain()` family of functions on collections. These methods let you move
+elements out of a collection while allowing them to retain their backing
+memory, reducing allocation in certain situations.
+
+A number of implementations of `From` for converting between standard library
+types, mainly between various integral and floating-point types.
+
+Finally, `Vec::extend_from_slice()`, which was previously known as
+`push_all()`. This method has a significantly faster implementation than the
+more general `extend()`.
+
+See the detailed release notes linked above for more.
+
+#### Crates.io disallows wildcards
+
+If you maintain a crate on [Crates.io](https://crates.io), you might have seen
+a warning: newly uploaded crates are no longer allowed to use a wildcard when
+describing their dependencies. In other words, this is not allowed:
+
+```toml
+[dependencies]
+regex = "*"
+```
+
+Instead, you must actually specify a specific version or range of versions,
+using one of the `semver` crate’s various options: `^`, `~`, or `=`.
+
+A wildcard dependency means that you work with any possible version of your
+dependency. This is highly unlikely to be true, and causes unnecessary breakage
+in the ecosystem. We’ve been advertising this change as a warning for some time;
+now it’s time to turn it into an error.
+
+### Contributors to 1.6
+
+TODO