Auto merge of #46327 - Aaronepower:master, r=alexcrichton

Updated RELEASES.md for 1.23.0

[Rendered](https://github.com/Aaronepower/rust/blob/master/RELEASES.md)

Author: bors

RELEASES.md

@@ -1,3 +1,96 @@
+Version 1.23.0 (2018-01-04)
+==========================
+
+Language
+--------
+- [Arbitrary `auto` traits are now permitted in trait objects.][45772]
+- [rustc now uses subtyping on the left hand side of binary operations.][45435]
+  Which should fix some confusing errors in some operations.
+
+Compiler
+--------
+- [Enabled `TrapUnreachable` in LLVM which should mitigate the impact of
+  undefined behaviour.][45920]
+- [rustc now suggests renaming import if names clash.][45660]
+- [Display errors/warnings correctly when there are zero-width or
+  wide characters.][45711]
+- [rustc now avoids unnecessary copies of arguments that are
+  simple bindings][45380] This should improve memory usage on average by 5-10%.
+- [Updated musl used to build musl rustc to 1.1.17][45393]
+
+Libraries
+---------
+- [Allow a trailing comma in `assert_eq/ne` macro][45887]
+- [Implement Hash for raw pointers to unsized types][45483]
+- [impl `From<*mut T>` for `AtomicPtr<T>`][45610]
+- [impl `From<usize/isize>` for `AtomicUsize/AtomicIsize`.][45610]
+- [Removed the `T: Sync` requirement for `RwLock<T>: Send`][45267]
+- [Removed `T: Sized` requirement for `{<*const T>, <*mut T>}::as_ref`
+  and `<*mut T>::as_mut`][44932]
+- [Optimized `Thread::{park, unpark}` implementation][45524]
+- [Improved `SliceExt::binary_search` performance.][45333]
+- [impl `FromIterator<()>` for `()`][45379]
+- [Copied `AsciiExt` trait methods to primitive types.][44042] Use of `AsciiExt`
+  is now deprecated.
+
+Stabilized APIs
+---------------
+
+Cargo
+-----
+- [Cargo now supports alternative registries][cargo/4506]
+- [Cargo now supports uninstallation of multiple packages][cargo/4561]
+  eg. `cargo uninstall foo bar` uninstalls `foo` and `bar`.
+- [Added unit test checking to `cargo check`][cargo/4592]
+- [Cargo now lets you install a specific version
+  using `cargo install --version`][cargo/4637]
+
+Misc
+----
+- [Releases now ship with the Cargo book documentation.][45692]
+- [rustdoc now prints rendering warnings on every run.][45324]
+- [Release tarballs now come with rustfmt][45903]
+
+Compatibility Notes
+-------------------
+- [Changes have been made to type equality to make it more correct,
+  in rare cases this could break some code.][45853] [Tracking issue for
+  further information][45852]
+- [`char::escape_debug` now uses Unicode 10 over 9.][45571]
+- [Upgraded Android SDK to 27, and NDK to r15c.][45580] This drops support for
+  Android 9, the minimum supported version is Android 14.
+- [Bumped the minimum LLVM to 3.9][45326]
+
+[44042]: https://github.com/rust-lang/rust/pull/44042
+[44932]: https://github.com/rust-lang/rust/pull/44932
+[45267]: https://github.com/rust-lang/rust/pull/45267
+[45324]: https://github.com/rust-lang/rust/pull/45324
+[45326]: https://github.com/rust-lang/rust/pull/45326
+[45333]: https://github.com/rust-lang/rust/pull/45333
+[45379]: https://github.com/rust-lang/rust/pull/45379
+[45380]: https://github.com/rust-lang/rust/pull/45380
+[45393]: https://github.com/rust-lang/rust/pull/45393
+[45435]: https://github.com/rust-lang/rust/pull/45435
+[45483]: https://github.com/rust-lang/rust/pull/45483
+[45524]: https://github.com/rust-lang/rust/pull/45524
+[45571]: https://github.com/rust-lang/rust/pull/45571
+[45580]: https://github.com/rust-lang/rust/pull/45580
+[45610]: https://github.com/rust-lang/rust/pull/45610
+[45660]: https://github.com/rust-lang/rust/pull/45660
+[45692]: https://github.com/rust-lang/rust/pull/45692
+[45711]: https://github.com/rust-lang/rust/pull/45711
+[45772]: https://github.com/rust-lang/rust/pull/45772
+[45852]: https://github.com/rust-lang/rust/issues/45852
+[45853]: https://github.com/rust-lang/rust/pull/45853
+[45887]: https://github.com/rust-lang/rust/pull/45887
+[45903]: https://github.com/rust-lang/rust/pull/45903
+[45920]: https://github.com/rust-lang/rust/pull/45920
+[cargo/4506]: https://github.com/rust-lang/cargo/pull/4506
+[cargo/4561]: https://github.com/rust-lang/cargo/pull/4561
+[cargo/4592]: https://github.com/rust-lang/cargo/pull/4592
+[cargo/4637]: https://github.com/rust-lang/cargo/pull/4637
+
+
 Version 1.22.1 (2017-11-22)
 ==========================