Rollup of 16 pull requests

RELEASES.md

@@ -1,3 +1,104 @@
+Version 1.36.0 (2019-07-04)
+==========================
+
+Language
+--------
+- [Non-Lexical Lifetimes are now enabled on the 2015 edition.][59114]
+- [The order of traits in trait objects no longer affects the semantics of that
+  object.][59445] e.g. `dyn Send + fmt::Debug` is now equivalent to
+  `dyn fmt::Debug + Send`, where this was previously not the case.
+
+Libraries
+---------
+- [`HashMap`'s implementation has been replaced with `hashbrown::HashMap` implementation.][58623]
+- [`TryFromSliceError` now implements `From<Infallible>`.][60318]
+- [`mem::needs_drop` is now available as a const fn.][60364]
+- [`alloc::Layout::from_size_align_unchecked` is now available as a const fn.][60370]
+- [`String` now implements `BorrowMut<str>`.][60404]
+- [`io::Cursor` now implements `Default`.][60234]
+- [Both `NonNull::{dangling, cast}` are now const fns.][60244]
+- [The `alloc` crate is now stable.][59675] `alloc` allows you to use a subset
+  of `std` (e.g. `Vec`, `Box`, `Arc`) in `#![no_std]` environments if the
+  environment has access to heap memory allocation.
+- [`String` now implements `From<&String>`.][59825]
+- [You can now pass multiple arguments to the `dbg!` macro.][59826] `dbg!` will
+  return a tuple of each argument when there is multiple arguments.
+- [`Result::{is_err, is_ok}` are now `#[must_use]` and will produce a warning if
+  not used.][59648]
+
+Stabilized APIs
+---------------
+- [`VecDeque::rotate_left`]
+- [`VecDeque::rotate_right`]
+- [`Iterator::copied`]
+- [`io::IoSlice`]
+- [`io::IoSliceMut`]
+- [`Read::read_vectored`]
+- [`Write::write_vectored`]
+- [`str::as_mut_ptr`]
+- [`mem::MaybeUninit`]
+- [`pointer::align_offset`]
+- [`future::Future`]
+- [`task::Context`] 
+- [`task::RawWaker`]
+- [`task::RawWakerVTable`]
+- [`task::Waker`]
+- [`task::Poll`]
+
+Cargo
+-----
+- [Cargo will now produce an error if you attempt to use the name of a required dependency as a feature.][cargo/6860]
+- [You can now pass the `--offline` flag to run cargo without accessing the network.][cargo/6934]
+
+You can find further change's in [Cargo's 1.36.0 release notes][cargo-1-36-0].
+
+Clippy
+------
+There have been numerous additions and fixes to clippy, see [Clippy's 1.36.0 release notes][clippy-1-36-0] for more details.
+
+Misc
+----
+
+Compatibility Notes
+-------------------
+- With the stabilisation of `mem::MaybeUninit`, `mem::uninitialized` use is no
+  longer recommended, and will be deprecated in 1.38.0.
+
+[60318]: https://github.com/rust-lang/rust/pull/60318/
+[60364]: https://github.com/rust-lang/rust/pull/60364/
+[60370]: https://github.com/rust-lang/rust/pull/60370/
+[60404]: https://github.com/rust-lang/rust/pull/60404/
+[60234]: https://github.com/rust-lang/rust/pull/60234/
+[60244]: https://github.com/rust-lang/rust/pull/60244/
+[58623]: https://github.com/rust-lang/rust/pull/58623/
+[59648]: https://github.com/rust-lang/rust/pull/59648/
+[59675]: https://github.com/rust-lang/rust/pull/59675/
+[59825]: https://github.com/rust-lang/rust/pull/59825/
+[59826]: https://github.com/rust-lang/rust/pull/59826/
+[59445]: https://github.com/rust-lang/rust/pull/59445/
+[59114]: https://github.com/rust-lang/rust/pull/59114/
+[cargo/6860]: https://github.com/rust-lang/cargo/pull/6860/
+[cargo/6934]: https://github.com/rust-lang/cargo/pull/6934/
+[`VecDeque::rotate_left`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.rotate_left
+[`VecDeque::rotate_right`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.rotate_right
+[`Iterator::copied`]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#tymethod.copied
+[`io::IoSlice`]: https://doc.rust-lang.org/std/io/struct.IoSlice.html
+[`io::IoSliceMut`]: https://doc.rust-lang.org/std/io/struct.IoSliceMut.html
+[`Read::read_vectored`]: https://doc.rust-lang.org/std/io/trait.Read.html#method.read_vectored
+[`Write::write_vectored`]: https://doc.rust-lang.org/std/io/trait.Write.html#method.write_vectored
+[`str::as_mut_ptr`]: https://doc.rust-lang.org/std/primitive.str.html#method.as_mut_ptr
+[`mem::MaybeUninit`]: https://doc.rust-lang.org/std/mem/union.MaybeUninit.html
+[`pointer::align_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.align_offset
+[`future::Future`]: https://doc.rust-lang.org/std/future/trait.Future.html
+[`task::Context`]: https://doc.rust-lang.org/beta/std/task/struct.Context.html
+[`task::RawWaker`]: https://doc.rust-lang.org/beta/std/task/struct.RawWaker.html
+[`task::RawWakerVTable`]: https://doc.rust-lang.org/beta/std/task/struct.RawWakerVTable.html
+[`task::Waker`]: https://doc.rust-lang.org/beta/std/task/struct.Waker.html
+[`task::Poll`]: https://doc.rust-lang.org/beta/std/task/enum.Poll.html
+[clippy-1-36-0]: https://github.com/rust-lang/rust-clippy/blob/master/CHANGELOG.md#rust-136
+[cargo-1-36-0]: https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-136-2019-07-04
+
+
 Version 1.35.0 (2019-05-23)
 ==========================
 
@@ -62,7 +163,7 @@ Cargo
 - [You can now set `cargo:rustc-cdylib-link-arg` at build time to pass custom
   linker arguments when building a `cdylib`.][cargo/6298] Its usage is highly
   platform specific.
-  
+
 Misc
 ----
 - [The Rust toolchain is now available natively for musl based distros.][58575]

src/doc/unstable-book/src/language-features/unsized-locals.md

@@ -117,9 +117,7 @@ fn main () {
 }
 ```
 
-One of the objectives of this feature is to allow `Box<dyn FnOnce>`, instead of `Box<dyn FnBox>` in the future. See [#28796] for details.
-
-[#28796]: https://github.com/rust-lang/rust/issues/28796
+One of the objectives of this feature is to allow `Box<dyn FnOnce>`.
 
 ## Variable length arrays
 

src/liballoc/boxed.rs

@@ -761,85 +761,6 @@ impl<A, F: Fn<A> + ?Sized> Fn<A> for Box<F> {
     }
 }
 
-/// `FnBox` is deprecated and will be removed.
-/// `Box<dyn FnOnce()>` can be called directly, since Rust 1.35.0.
-///
-/// `FnBox` is a version of the `FnOnce` intended for use with boxed
-/// closure objects. The idea was that where one would normally store a
-/// `Box<dyn FnOnce()>` in a data structure, you whould use
-/// `Box<dyn FnBox()>`. The two traits behave essentially the same, except
-/// that a `FnBox` closure can only be called if it is boxed.
-///
-/// # Examples
-///
-/// Here is a snippet of code which creates a hashmap full of boxed
-/// once closures and then removes them one by one, calling each
-/// closure as it is removed. Note that the type of the closures
-/// stored in the map is `Box<dyn FnBox() -> i32>` and not `Box<dyn FnOnce()
-/// -> i32>`.
-///
-/// ```
-/// #![feature(fnbox)]
-/// #![allow(deprecated)]
-///
-/// use std::boxed::FnBox;
-/// use std::collections::HashMap;
-///
-/// fn make_map() -> HashMap<i32, Box<dyn FnBox() -> i32>> {
-///     let mut map: HashMap<i32, Box<dyn FnBox() -> i32>> = HashMap::new();
-///     map.insert(1, Box::new(|| 22));
-///     map.insert(2, Box::new(|| 44));
-///     map
-/// }
-///
-/// fn main() {
-///     let mut map = make_map();
-///     for i in &[1, 2] {
-///         let f = map.remove(&i).unwrap();
-///         assert_eq!(f(), i * 22);
-///     }
-/// }
-/// ```
-///
-/// In Rust 1.35.0 or later, use `FnOnce`, `FnMut`, or `Fn` instead:
-///
-/// ```
-/// use std::collections::HashMap;
-///
-/// fn make_map() -> HashMap<i32, Box<dyn FnOnce() -> i32>> {
-///     let mut map: HashMap<i32, Box<dyn FnOnce() -> i32>> = HashMap::new();
-///     map.insert(1, Box::new(|| 22));
-///     map.insert(2, Box::new(|| 44));
-///     map
-/// }
-///
-/// fn main() {
-///     let mut map = make_map();
-///     for i in &[1, 2] {
-///         let f = map.remove(&i).unwrap();
-///         assert_eq!(f(), i * 22);
-///     }
-/// }
-/// ```
-#[rustc_paren_sugar]
-#[unstable(feature = "fnbox", issue = "28796")]
-#[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
-pub trait FnBox<A>: FnOnce<A> {
-    /// Performs the call operation.
-    fn call_box(self: Box<Self>, args: A) -> Self::Output;
-}
-
-#[unstable(feature = "fnbox", issue = "28796")]
-#[rustc_deprecated(reason = "use `FnOnce`, `FnMut`, or `Fn` instead", since = "1.37.0")]
-#[allow(deprecated, deprecated_in_future)]
-impl<A, F> FnBox<A> for F
-    where F: FnOnce<A>
-{
-    fn call_box(self: Box<F>, args: A) -> F::Output {
-        self.call_once(args)
-    }
-}
-
 #[unstable(feature = "coerce_unsized", issue = "27732")]
 impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Box<U>> for Box<T> {}
 

src/libcore/intrinsics.rs

@@ -36,6 +36,8 @@
             issue = "0")]
 #![allow(missing_docs)]
 
+use crate::mem;
+
 #[stable(feature = "drop_in_place", since = "1.8.0")]
 #[rustc_deprecated(reason = "no longer an intrinsic - use `ptr::drop_in_place` directly",
                    since = "1.18.0")]
@@ -700,17 +702,15 @@ extern "rust-intrinsic" {
     /// which is unsafe unless `T` is `Copy`. Also, even if T is
     /// `Copy`, an all-zero value may not correspond to any legitimate
     /// state for the type in question.
+    #[unstable(feature = "core_intrinsics",
+               reason = "intrinsics are unlikely to ever be stabilized, instead \
+                         they should be used through stabilized interfaces \
+                         in the rest of the standard library",
+               issue = "0")]
+    #[rustc_deprecated(reason = "no longer used by rustc, will be removed - use MaybeUnint instead",
+                       since = "1.37.0")]
     pub fn init<T>() -> T;
 
-    /// Creates an uninitialized value.
-    ///
-    /// `uninit` is unsafe because there is no guarantee of what its
-    /// contents are. In particular its drop-flag may be set to any
-    /// state, which means it may claim either dropped or
-    /// undropped. In the general case one must use `ptr::write` to
-    /// initialize memory previous set to the result of `uninit`.
-    pub fn uninit<T>() -> T;
-
     /// Moves a value out of scope without running drop glue.
     pub fn forget<T: ?Sized>(_: T);
 
@@ -1331,6 +1331,26 @@ extern "rust-intrinsic" {
 // (`transmute` also falls into this category, but it cannot be wrapped due to the
 // check that `T` and `U` have the same size.)
 
+/// Checks whether `ptr` is properly aligned with respect to
+/// `align_of::<T>()`.
+pub(crate) fn is_aligned_and_not_null<T>(ptr: *const T) -> bool {
+    !ptr.is_null() && ptr as usize % mem::align_of::<T>() == 0
+}
+
+/// Checks whether the regions of memory starting at `src` and `dst` of size
+/// `count * size_of::<T>()` overlap.
+fn overlaps<T>(src: *const T, dst: *const T, count: usize) -> bool {
+    let src_usize = src as usize;
+    let dst_usize = dst as usize;
+    let size = mem::size_of::<T>().checked_mul(count).unwrap();
+    let diff = if src_usize > dst_usize {
+        src_usize - dst_usize
+    } else {
+        dst_usize - src_usize
+    };
+    size > diff
+}
+
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
 /// and destination must *not* overlap.
 ///
@@ -1420,7 +1440,11 @@ pub unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
-    copy_nonoverlapping(src, dst, count);
+
+    debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
+    debug_assert!(!overlaps(src, dst, count), "attempt to copy to overlapping memory");
+    copy_nonoverlapping(src, dst, count)
 }
 
 /// Copies `count * size_of::<T>()` bytes from `src` to `dst`. The source
@@ -1480,6 +1504,9 @@ pub unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
         fn copy<T>(src: *const T, dst: *mut T, count: usize);
     }
+
+    debug_assert!(is_aligned_and_not_null(src), "attempt to copy from unaligned or null pointer");
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to copy to unaligned or null pointer");
     copy(src, dst, count)
 }
 
@@ -1561,6 +1588,8 @@ pub unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
     extern "rust-intrinsic" {
         fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
     }
+
+    debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
     write_bytes(dst, val, count)
 }
 

src/libcore/mem/mod.rs

@@ -450,8 +450,7 @@ pub const fn needs_drop<T>() -> bool {
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn zeroed<T>() -> T {
-    intrinsics::panic_if_uninhabited::<T>();
-    intrinsics::init()
+    MaybeUninit::zeroed().assume_init()
 }
 
 /// Bypasses Rust's normal memory-initialization checks by pretending to
@@ -476,8 +475,7 @@ pub unsafe fn zeroed<T>() -> T {
 #[rustc_deprecated(since = "1.38.0", reason = "use `mem::MaybeUninit` instead")]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn uninitialized<T>() -> T {
-    intrinsics::panic_if_uninhabited::<T>();
-    intrinsics::uninit()
+    MaybeUninit::uninit().assume_init()
 }
 
 /// Swaps the values at two mutable locations, without deinitializing either one.