Rollup merge of #84094 - tmiasko:remove-fixed-size-array, r=m-ou-se

Remove FixedSizeArray

Remove `FixedSizeArray` trait, it has been superseded by const generics.

Closes #27778.

Author: Dylan-DPC

library/core/src/array/mod.rs

@@ -12,7 +12,6 @@ use crate::convert::{Infallible, TryFrom};
 use crate::fmt;
 use crate::hash::{self, Hash};
 use crate::iter::TrustedLen;
-use crate::marker::Unsize;
 use crate::mem::{self, MaybeUninit};
 use crate::ops::{Index, IndexMut};
 use crate::slice::{Iter, IterMut};
@@ -36,41 +35,6 @@ pub fn from_mut<T>(s: &mut T) -> &mut [T; 1] {
     unsafe { &mut *(s as *mut T).cast::<[T; 1]>() }
 }
 
-/// 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. A 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.
-#[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)]

library/core/tests/array.rs

@@ -1,24 +1,6 @@
-use core::array::{self, FixedSizeArray, IntoIter};
+use core::array::{self, IntoIter};
 use core::convert::TryFrom;
 
-#[test]
-fn fixed_size_array() {
-    let mut array = [0; 64];
-    let mut zero_sized = [(); 64];
-    let mut empty_array = [0; 0];
-    let mut empty_zero_sized = [(); 0];
-
-    assert_eq!(FixedSizeArray::as_slice(&array).len(), 64);
-    assert_eq!(FixedSizeArray::as_slice(&zero_sized).len(), 64);
-    assert_eq!(FixedSizeArray::as_slice(&empty_array).len(), 0);
-    assert_eq!(FixedSizeArray::as_slice(&empty_zero_sized).len(), 0);
-
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut array).len(), 64);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut zero_sized).len(), 64);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut empty_array).len(), 0);
-    assert_eq!(FixedSizeArray::as_mut_slice(&mut empty_zero_sized).len(), 0);
-}
-
 #[test]
 fn array_from_ref() {
     let value: String = "Hello World!".into();

library/core/tests/lib.rs

@@ -27,7 +27,6 @@
 #![feature(duration_zero)]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
-#![feature(fixed_size_array)]
 #![feature(flt2dec)]
 #![feature(fmt_internals)]
 #![feature(hashmap_internals)]

library/std/src/lib.rs

@@ -214,7 +214,6 @@
     feature(slice_index_methods, coerce_unsized, sgx_platform)
 )]
 #![deny(rustc::existing_doc_keyword)]
-#![cfg_attr(all(test, target_vendor = "fortanix", target_env = "sgx"), feature(fixed_size_array))]
 // std is implemented with unstable features, many of which are internal
 // compiler details that will never be stable
 // NB: the following list is sorted to minimize merge conflicts.