Auto merge of #58656 - Mark-Simulacrum:beta-rollups, r=pietroalbini

Beta rollups

 - #58649
 - #58592
 - #58574
 - #58227
 - #58056
 - #57859
 - #57710

A few of these are via #58641.

r? @pietroalbini

RELEASES.md

@@ -1,3 +1,151 @@
+Version 1.33.0 (2019-02-28)
+==========================
+
+Language
+--------
+- [You can now use the `cfg(target_vendor)` attribute.][57465] E.g.
+ `#[cfg(target_vendor="linux")] fn main() { println!("Hello Linux!"); }`
+- [Integer patterns such as in a match expression can now be exhaustive.][56362]
+ E.g. You can have match statement on a `u8` that covers `0..=255` and
+ you would no longer be required to have a `_ => unreachable!()` case. 
+- [You can now have multiple patterns in `if let` and `while let`
+ expressions.][57532] You can do this with the same syntax as a `match`
+ expression. E.g.
+ ```rust
+ enum Creature {
+ Crab(String),
+ Lobster(String),
+ Person(String),
+ }
+
+ fn main() {
+ let state = Creature::Crab("Ferris");
+
+ if let Creature::Crab(name) | Creature::Person(name) = state {
+ println!("This creature's name is: {}", name);
+ }
+ }
+ ```
+- [You can now have irrefutable `if let` and `while let` patterns.][57535] Using
+ this feature will by default produce a warning as this behaviour can be
+ unintuitive. E.g. `if let _ = 5 {}`
+- [You can now use `let` bindings, assignments, expression statements,
+ and irrefutable pattern destructuring in const functions.][57175]
+- [You can now call unsafe const functions.][57067] E.g.
+ ```rust
+ const unsafe fn foo() -> i32 { 5 }
+ const fn bar() -> i32 {
+ unsafe { foo() }
+ }
+ ```
+- [You can now specify multiple attributes in a `cfg_attr` attribute.][57332]
+ E.g. `#[cfg_attr(all(), must_use, optimize)]`
+- [You can now specify a specific alignment with the `#[repr(packed)]`
+ attribute.][57049] E.g. `#[repr(packed(2))] struct Foo(i16, i32);` is a struct
+ with an alignment of 2 bytes and a size of 6 bytes.
+- [You can now import an item from a module as an `_`.][56303] This allows you to
+ import a trait's impls, and not have the name in the namespace. E.g.
+ ```rust
+ use std::io::Read as _;
+
+ // Allowed as there is only one `Read` in the module.
+ pub trait Read {}
+ ```
+- [`extern` functions will now abort by default when panicking.][55982]
+ This was previously undefined behaviour.
+
+Compiler
+--------
+- [You can now set a linker flavor for `rustc` with the `-Clinker-flavor`
+ command line argument.][56351]
+- [The mininum required LLVM version has been bumped to 6.0.][56642]
+- [Added support for the PowerPC64 architecture on FreeBSD.][57615]
+- [The `x86_64-fortanix-unknown-sgx` target support has been upgraded to
+ tier 2 support.][57130] Visit the [platform support][platform-support] page for
+ information on Rust's platform support.
+- [Added support for the `thumbv7neon-linux-androideabi` and
+ `thumbv7neon-unknown-linux-gnueabihf` targets.][56947]
+- [Added support for the `x86_64-unknown-uefi` target.][56769]
+
+Libraries
+---------
+- [The methods `overflowing_{add, sub, mul, shl, shr}` are now `const`
+ functions for all numeric types.][57566]
+- [The methods `rotate_left`, `rotate_right`, and `wrapping_{add, sub, mul, shl, shr}`
+ are now `const` functions for all numeric types.][57105]
+- [The methods `is_positive` and `is_negative` are now `const` functions for
+ all signed numeric types.][57105]
+- [The `get` method for all `NonZero` types is now `const`.][57167]
+- [The methods `count_ones`, `count_zeros`, `leading_zeros`, `trailing_zeros`,
+ `swap_bytes`, `from_be`, `from_le`, `to_be`, `to_le` are now `const` for all
+ numeric types.][57234]
+- [`Ipv4Addr::new` is now a `const` function][57234]
+
+Stabilized APIs
+---------------
+- [`unix::FileExt::read_exact_at`]
+- [`unix::FileExt::write_all_at`]
+- [`Option::transpose`]
+- [`Result::transpose`]
+- [`convert::identity`]
+- [`pin::Pin`]
+- [`marker::Unpin`]
+- [`marker::PhantomPinned`]
+- [`Vec::resize_with`]
+- [`VecDeque::resize_with`]
+- [`Duration::as_millis`]
+- [`Duration::as_micros`]
+- [`Duration::as_nanos`]
+
+
+Cargo
+-----
+- [Cargo should now rebuild a crate if a file was modified during the initial
+ build.][cargo/6484]
+
+Compatibility Notes
+-------------------
+- The methods `str::{trim_left, trim_right, trim_left_matches, trim_right_matches}`
+ are now deprecated in the standard library, and their usage will now produce a warning.
+ Please use the `str::{trim_start, trim_end, trim_start_matches, trim_end_matches}`
+ methods instead.
+
+[57615]: https://github.com/rust-lang/rust/pull/57615/
+[57465]: https://github.com/rust-lang/rust/pull/57465/
+[57532]: https://github.com/rust-lang/rust/pull/57532/
+[57535]: https://github.com/rust-lang/rust/pull/57535/
+[57566]: https://github.com/rust-lang/rust/pull/57566/
+[57130]: https://github.com/rust-lang/rust/pull/57130/
+[57167]: https://github.com/rust-lang/rust/pull/57167/
+[57175]: https://github.com/rust-lang/rust/pull/57175/
+[57234]: https://github.com/rust-lang/rust/pull/57234/
+[57332]: https://github.com/rust-lang/rust/pull/57332/
+[56947]: https://github.com/rust-lang/rust/pull/56947/
+[57049]: https://github.com/rust-lang/rust/pull/57049/
+[57067]: https://github.com/rust-lang/rust/pull/57067/
+[56769]: https://github.com/rust-lang/rust/pull/56769/
+[56642]: https://github.com/rust-lang/rust/pull/56642/
+[56303]: https://github.com/rust-lang/rust/pull/56303/
+[56351]: https://github.com/rust-lang/rust/pull/56351/
+[55982]: https://github.com/rust-lang/rust/pull/55982/
+[56362]: https://github.com/rust-lang/rust/pull/56362
+[57105]: https://github.com/rust-lang/rust/pull/57105
+[cargo/6484]: https://github.com/rust-lang/cargo/pull/6484/
+[`unix::FileExt::read_exact_at`]: https://doc.rust-lang.org/std/os/unix/fs/trait.FileExt.html#method.read_exact_at
+[`unix::FileExt::write_all_at`]: https://doc.rust-lang.org/std/os/unix/fs/trait.FileExt.html#method.write_all_at
+[`Option::transpose`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.transpose
+[`Result::transpose`]: https://doc.rust-lang.org/std/result/enum.Result.html#method.transpose
+[`convert::identity`]: https://doc.rust-lang.org/std/convert/fn.identity.html
+[`pin::Pin`]: https://doc.rust-lang.org/std/pin/struct.Pin.html
+[`marker::Unpin`]: https://doc.rust-lang.org/stable/std/marker/trait.Unpin.html
+[`marker::PhantomPinned`]: https://doc.rust-lang.org/nightly/std/marker/struct.PhantomPinned.html
+[`Vec::resize_with`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.resize_with
+[`VecDeque::resize_with`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.resize_with
+[`Duration::as_millis`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_millis
+[`Duration::as_micros`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_micros
+[`Duration::as_nanos`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.as_nanos
+[platform-support]: https://forge.rust-lang.org/platform-support.html
+
 Version 1.32.0 (2019-01-17)
 ==========================
 

src/libcore/marker.rs

@@ -597,34 +597,43 @@ unsafe impl<T: ?Sized> Freeze for &mut T {}
 
 /// Types which can be safely moved after being pinned.
 ///
-/// Since Rust itself has no notion of immovable types, and will consider moves to always be safe,
+/// Since Rust itself has no notion of immovable types, and considers moves
+/// (e.g. through assignment or [`mem::replace`]) to always be safe,
 /// this trait cannot prevent types from moving by itself.
 ///
-/// Instead it can be used to prevent moves through the type system,
-/// by controlling the behavior of pointers wrapped in the [`Pin`] wrapper,
+/// Instead it is used to prevent moves through the type system,
+/// by controlling the behavior of pointers `P` wrapped in the [`Pin<P>`] wrapper,
 /// which "pin" the type in place by not allowing it to be moved out of them.
 /// See the [`pin module`] documentation for more information on pinning.
 ///
 /// Implementing this trait lifts the restrictions of pinning off a type,
-/// which then allows it to move out with functions such as [`replace`].
+/// which then allows it to move out with functions such as [`mem::replace`].
+///
+/// `Unpin` has no consequence at all for non-pinned data. In particular,
+/// [`mem::replace`] happily moves `!Unpin` data (it works for any `&mut T`, not
+/// just when `T: Unpin`). However, you cannot use
+/// [`mem::replace`] on data wrapped inside a [`Pin<P>`] because you cannot get the
+/// `&mut T` you need for that, and *that* is what makes this system work.
 ///
 /// So this, for example, can only be done on types implementing `Unpin`:
 ///
 /// ```rust
-/// use std::mem::replace;
+/// use std::mem;
 /// use std::pin::Pin;
 ///
 /// let mut string = "this".to_string();
 /// let mut pinned_string = Pin::new(&mut string);
 ///
-/// // dereferencing the pointer mutably is only possible because String implements Unpin
-/// replace(&mut *pinned_string, "other".to_string());
+/// // We need a mutable reference to call `mem::replace`.
+/// // We can obtain such a reference by (implicitly) invoking `Pin::deref_mut`,
+/// // but that is only possible because `String` implements `Unpin`.
+/// mem::replace(&mut *pinned_string, "other".to_string());
 /// ```
 ///
 /// This trait is automatically implemented for almost every type.
 ///
-/// [`replace`]: ../../std/mem/fn.replace.html
-/// [`Pin`]: ../pin/struct.Pin.html
+/// [`mem::replace`]: ../../std/mem/fn.replace.html
+/// [`Pin<P>`]: ../pin/struct.Pin.html
 /// [`pin module`]: ../../std/pin/index.html
 #[stable(feature = "pin", since = "1.33.0")]
 pub auto trait Unpin {}