Add `array::IntoIter` as a consuming/by-value array iterator

The iterator is implemented using const generics. It implements the
traits `Iterator`, `DoubleEndedIterator`, `ExactSizeIterator`,
`FusedIterator` and `TrustedLen`. It also contains a public method
`new` to create it from an array.

`IntoIterator` was not implemented for arrays yet, as there are still
some open questions regarding backwards compatibility. This commit
only adds the iterator impl and does not yet offer a convenient way
to obtain that iterator.

1 files changed, 0 insertions, 425 deletions

diff --git a/src/libcore/array.rs b/src/libcore/array.rs
deleted file mode 100644
index b5614010e5c..00000000000
--- a/src/libcore/array.rs
+++ /dev/null
@@ -1,425 +0,0 @@
-//! Implementations of things like `Eq` for fixed-length arrays
-//! up to a certain length. Eventually we should able to generalize
-//! to all lengths.
-//!
-//! *[See also the array primitive type](../../std/primitive.array.html).*
-
-#![stable(feature = "core_array", since = "1.36.0")]
-
-use crate::borrow::{Borrow, BorrowMut};
-use crate::cmp::Ordering;
-use crate::convert::{Infallible, TryFrom};
-use crate::fmt;
-use crate::hash::{Hash, self};
-use crate::marker::Unsize;
-use crate::slice::{Iter, IterMut};
-
-/// Utility trait implemented only on arrays of fixed size
-///
-/// This trait can be used to implement other traits on fixed-size arrays
-/// without causing much metadata bloat.
-///
-/// The trait is marked unsafe in order to restrict implementors to fixed-size
-/// arrays. User of this trait can assume that implementors have the exact
-/// layout in memory of a fixed size array (for example, for unsafe
-/// initialization).
-///
-/// Note that the traits [`AsRef`] and [`AsMut`] provide similar methods for types that
-/// may not be fixed-size arrays. Implementors should prefer those traits
-/// instead.
-///
-/// [`AsRef`]: ../convert/trait.AsRef.html
-/// [`AsMut`]: ../convert/trait.AsMut.html
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-pub unsafe trait FixedSizeArray<T> {
-    /// Converts the array to immutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_slice(&self) -> &[T];
-    /// Converts the array to mutable slice
-    #[unstable(feature = "fixed_size_array", issue = "27778")]
-    fn as_mut_slice(&mut self) -> &mut [T];
-}
-
-#[unstable(feature = "fixed_size_array", issue = "27778")]
-unsafe impl<T, A: Unsize<[T]>> FixedSizeArray<T> for A {
-    #[inline]
-    fn as_slice(&self) -> &[T] {
-        self
-    }
-    #[inline]
-    fn as_mut_slice(&mut self) -> &mut [T] {
-        self
-    }
-}
-
-/// The error type returned when a conversion from a slice to an array fails.
-#[stable(feature = "try_from", since = "1.34.0")]
-#[derive(Debug, Copy, Clone)]
-pub struct TryFromSliceError(());
-
-#[stable(feature = "core_array", since = "1.36.0")]
-impl fmt::Display for TryFromSliceError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(self.__description(), f)
-    }
-}
-
-impl TryFromSliceError {
-    #[unstable(feature = "array_error_internals",
-           reason = "available through Error trait and this method should not \
-                     be exposed publicly",
-           issue = "0")]
-    #[inline]
-    #[doc(hidden)]
-    pub fn __description(&self) -> &str {
-        "could not convert slice to array"
-    }
-}
-
-#[stable(feature = "try_from_slice_error", since = "1.36.0")]
-impl From<Infallible> for TryFromSliceError {
-    fn from(x: Infallible) -> TryFromSliceError {
-        match x {}
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsRef<[T]> for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    #[inline]
-    fn as_ref(&self) -> &[T] {
-        &self[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T, const N: usize> AsMut<[T]> for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    #[inline]
-    fn as_mut(&mut self) -> &mut [T] {
-        &mut self[..]
-    }
-}
-
-#[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> Borrow<[T]> for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    fn borrow(&self) -> &[T] {
-        self
-    }
-}
-
-#[stable(feature = "array_borrow", since = "1.4.0")]
-impl<T, const N: usize> BorrowMut<[T]> for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    fn borrow_mut(&mut self) -> &mut [T] {
-        self
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<T, const N: usize> TryFrom<&[T]> for [T; N]
-where
-    T: Copy,
-    [T; N]: LengthAtMost32,
-{
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &[T]) -> Result<[T; N], TryFromSliceError> {
-        <&Self>::try_from(slice).map(|r| *r)
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &[T]) -> Result<&[T; N], TryFromSliceError> {
-        if slice.len() == N {
-            let ptr = slice.as_ptr() as *const [T; N];
-            unsafe { Ok(&*ptr) }
-        } else {
-            Err(TryFromSliceError(()))
-        }
-    }
-}
-
-#[stable(feature = "try_from", since = "1.34.0")]
-impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    type Error = TryFromSliceError;
-
-    fn try_from(slice: &mut [T]) -> Result<&mut [T; N], TryFromSliceError> {
-        if slice.len() == N {
-            let ptr = slice.as_mut_ptr() as *mut [T; N];
-            unsafe { Ok(&mut *ptr) }
-        } else {
-            Err(TryFromSliceError(()))
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Hash, const N: usize> Hash for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    fn hash<H: hash::Hasher>(&self, state: &mut H) {
-        Hash::hash(&self[..], state)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: fmt::Debug, const N: usize> fmt::Debug for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&&self[..], f)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, const N: usize> IntoIterator for &'a [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    type Item = &'a T;
-    type IntoIter = Iter<'a, T>;
-
-    fn into_iter(self) -> Iter<'a, T> {
-        self.iter()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T, const N: usize> IntoIterator for &'a mut [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    type Item = &'a mut T;
-    type IntoIter = IterMut<'a, T>;
-
-    fn into_iter(self) -> IterMut<'a, T> {
-        self.iter_mut()
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[B; N]> for [A; N]
-where
-    A: PartialEq<B>,
-    [A; N]: LengthAtMost32,
-    [B; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &[B; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[B; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[B]> for [A; N]
-where
-    A: PartialEq<B>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &[B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B, const N: usize> PartialEq<[A; N]> for [B]
-where
-    B: PartialEq<A>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<&'b [B]> for [A; N]
-where
-    A: PartialEq<B>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &&'b [B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &&'b [B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b [B]
-where
-    B: PartialEq<A>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<&'b mut [B]> for [A; N]
-where
-    A: PartialEq<B>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &&'b mut [B]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &&'b mut [B]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'b, A, B, const N: usize> PartialEq<[A; N]> for &'b mut [B]
-where
-    B: PartialEq<A>,
-    [A; N]: LengthAtMost32,
-{
-    #[inline]
-    fn eq(&self, other: &[A; N]) -> bool {
-        self[..] == other[..]
-    }
-    #[inline]
-    fn ne(&self, other: &[A; N]) -> bool {
-        self[..] != other[..]
-    }
-}
-
-// NOTE: some less important impls are omitted to reduce code bloat
-// __impl_slice_eq2! { [A; $N], &'b [B; $N] }
-// __impl_slice_eq2! { [A; $N], &'b mut [B; $N] }
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Eq, const N: usize> Eq for [T; N] where [T; N]: LengthAtMost32 {}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: PartialOrd, const N: usize> PartialOrd for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    #[inline]
-    fn partial_cmp(&self, other: &[T; N]) -> Option<Ordering> {
-        PartialOrd::partial_cmp(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn lt(&self, other: &[T; N]) -> bool {
-        PartialOrd::lt(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn le(&self, other: &[T; N]) -> bool {
-        PartialOrd::le(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn ge(&self, other: &[T; N]) -> bool {
-        PartialOrd::ge(&&self[..], &&other[..])
-    }
-    #[inline]
-    fn gt(&self, other: &[T; N]) -> bool {
-        PartialOrd::gt(&&self[..], &&other[..])
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T: Ord, const N: usize> Ord for [T; N]
-where
-    [T; N]: LengthAtMost32,
-{
-    #[inline]
-    fn cmp(&self, other: &[T; N]) -> Ordering {
-        Ord::cmp(&&self[..], &&other[..])
-    }
-}
-
-/// Implemented for lengths where trait impls are allowed on arrays in core/std
-#[rustc_on_unimplemented(
-    message="arrays only have std trait implementations for lengths 0..=32",
-)]
-#[unstable(feature = "const_generic_impls_guard", issue = "0",
-    reason = "will never be stable, just a temporary step until const generics are stable")]
-pub trait LengthAtMost32 {}
-
-macro_rules! array_impls {
-    ($($N:literal)+) => {
-        $(
-            #[unstable(feature = "const_generic_impls_guard", issue = "0")]
-            impl<T> LengthAtMost32 for [T; $N] {}
-        )+
-    }
-}
-
-array_impls! {
-     0  1  2  3  4  5  6  7  8  9
-    10 11 12 13 14 15 16 17 18 19
-    20 21 22 23 24 25 26 27 28 29
-    30 31 32
-}
-
-// The Default impls cannot be generated using the array_impls! macro because
-// they require array literals.
-
-macro_rules! array_impl_default {
-    {$n:expr, $t:ident $($ts:ident)*} => {
-        #[stable(since = "1.4.0", feature = "array_default")]
-        impl<T> Default for [T; $n] where T: Default {
-            fn default() -> [T; $n] {
-                [$t::default(), $($ts::default()),*]
-            }
-        }
-        array_impl_default!{($n - 1), $($ts)*}
-    };
-    {$n:expr,} => {
-        #[stable(since = "1.4.0", feature = "array_default")]
-        impl<T> Default for [T; $n] {
-            fn default() -> [T; $n] { [] }
-        }
-    };
-}
-
-array_impl_default!{32, T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T T}