Auto merge of rust-lang#74060 - kpp:remove_length_at_most_32, r=dtolnay

Remove trait LengthAtMost32

This is a continuation of rust-lang#74026 preserving the original burrbull's commit.

I talked to @burrbull, he suggested me to finish his PR.

Author: bors

src/liballoc/boxed.rs

@@ -130,7 +130,6 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use core::any::Any;
-use core::array::LengthAtMost32;
 use core::borrow;
 use core::cmp::Ordering;
 use core::convert::{From, TryFrom};
@@ -871,10 +870,7 @@ impl From<Box<str>> for Box<[u8]> {
 }
 
 #[stable(feature = "box_from_array", since = "1.45.0")]
-impl<T, const N: usize> From<[T; N]> for Box<[T]>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> From<[T; N]> for Box<[T]> {
     /// Converts a `[T; N]` into a `Box<[T]>`
     ///
     /// This conversion moves the array to newly heap-allocated memory.
@@ -890,10 +886,7 @@ where
 }
 
 #[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
-impl<T, const N: usize> TryFrom<Box<[T]>> for Box<[T; N]>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> TryFrom<Box<[T]>> for Box<[T; N]> {
     type Error = Box<[T]>;
 
     fn try_from(boxed_slice: Box<[T]>) -> Result<Self, Self::Error> {

src/liballoc/collections/vec_deque.rs

@@ -9,7 +9,6 @@
 
 // ignore-tidy-filelength
 
-use core::array::LengthAtMost32;
 use core::cmp::{self, Ordering};
 use core::fmt;
 use core::hash::{Hash, Hasher};
@@ -2889,9 +2888,9 @@ macro_rules! __impl_slice_eq1 {
 __impl_slice_eq1! { [] VecDeque<A>, Vec<B>, }
 __impl_slice_eq1! { [] VecDeque<A>, &[B], }
 __impl_slice_eq1! { [] VecDeque<A>, &mut [B], }
-__impl_slice_eq1! { [const N: usize] VecDeque<A>, [B; N], [B; N]: LengthAtMost32 }
-__impl_slice_eq1! { [const N: usize] VecDeque<A>, &[B; N], [B; N]: LengthAtMost32 }
-__impl_slice_eq1! { [const N: usize] VecDeque<A>, &mut [B; N], [B; N]: LengthAtMost32 }
+__impl_slice_eq1! { [const N: usize] VecDeque<A>, [B; N], }
+__impl_slice_eq1! { [const N: usize] VecDeque<A>, &[B; N], }
+__impl_slice_eq1! { [const N: usize] VecDeque<A>, &mut [B; N], }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: PartialOrd> PartialOrd for VecDeque<A> {

src/liballoc/lib.rs

@@ -84,7 +84,6 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(coerce_unsized)]
 #![feature(const_btree_new)]
-#![feature(const_generic_impls_guard)]
 #![feature(const_generics)]
 #![feature(const_in_array_repeat_expressions)]
 #![feature(cow_is_borrowed)]

src/liballoc/rc.rs

@@ -235,7 +235,6 @@ use crate::boxed::Box;
 use std::boxed::Box;
 
 use core::any::Any;
-use core::array::LengthAtMost32;
 use core::borrow;
 use core::cell::Cell;
 use core::cmp::Ordering;
@@ -1516,10 +1515,7 @@ where
 }
 
 #[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
-impl<T, const N: usize> TryFrom<Rc<[T]>> for Rc<[T; N]>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> TryFrom<Rc<[T]>> for Rc<[T; N]> {
     type Error = Rc<[T]>;
 
     fn try_from(boxed_slice: Rc<[T]>) -> Result<Self, Self::Error> {

src/liballoc/sync.rs

@@ -7,7 +7,6 @@
 //! [arc]: struct.Arc.html
 
 use core::any::Any;
-use core::array::LengthAtMost32;
 use core::borrow;
 use core::cmp::Ordering;
 use core::convert::{From, TryFrom};
@@ -2162,10 +2161,7 @@ where
 }
 
 #[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
-impl<T, const N: usize> TryFrom<Arc<[T]>> for Arc<[T; N]>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> TryFrom<Arc<[T]>> for Arc<[T; N]> {
     type Error = Arc<[T]>;
 
     fn try_from(boxed_slice: Arc<[T]>) -> Result<Self, Self::Error> {

src/liballoc/vec.rs

@@ -59,7 +59,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::array::LengthAtMost32;
 use core::cmp::{self, Ordering};
 use core::fmt;
 use core::hash::{Hash, Hasher};
@@ -2378,18 +2377,18 @@ __impl_slice_eq1! { [] &mut [A], Vec<B>, #[stable(feature = "partialeq_vec_for_r
 __impl_slice_eq1! { [] Cow<'_, [A]>, Vec<B> where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
 __impl_slice_eq1! { [] Cow<'_, [A]>, &[B] where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
 __impl_slice_eq1! { [] Cow<'_, [A]>, &mut [B] where A: Clone, #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [const N: usize] Vec<A>, [B; N] where [B; N]: LengthAtMost32, #[stable(feature = "rust1", since = "1.0.0")] }
-__impl_slice_eq1! { [const N: usize] Vec<A>, &[B; N] where [B; N]: LengthAtMost32, #[stable(feature = "rust1", since = "1.0.0")] }
+__impl_slice_eq1! { [const N: usize] Vec<A>, [B; N], #[stable(feature = "rust1", since = "1.0.0")] }
+__impl_slice_eq1! { [const N: usize] Vec<A>, &[B; N], #[stable(feature = "rust1", since = "1.0.0")] }
 
 // NOTE: some less important impls are omitted to reduce code bloat
 // FIXME(Centril): Reconsider this?
-//__impl_slice_eq1! { [const N: usize] Vec<A>, &mut [B; N], [B; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] [A; N], Vec<B>, [A; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] &[A; N], Vec<B>, [A; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] &mut [A; N], Vec<B>, [A; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, [B; N], [B; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], [B; N]: LengthAtMost32 }
-//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], [B; N]: LengthAtMost32 }
+//__impl_slice_eq1! { [const N: usize] Vec<A>, &mut [B; N], }
+//__impl_slice_eq1! { [const N: usize] [A; N], Vec<B>, }
+//__impl_slice_eq1! { [const N: usize] &[A; N], Vec<B>, }
+//__impl_slice_eq1! { [const N: usize] &mut [A; N], Vec<B>, }
+//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, [B; N], }
+//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], }
+//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], }
 
 /// Implements comparison of vectors, lexicographically.
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -2493,10 +2492,7 @@ impl<T: Clone> From<&mut [T]> for Vec<T> {
 }
 
 #[stable(feature = "vec_from_array", since = "1.44.0")]
-impl<T, const N: usize> From<[T; N]> for Vec<T>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> From<[T; N]> for Vec<T> {
     #[cfg(not(test))]
     fn from(s: [T; N]) -> Vec<T> {
         <[T]>::into_vec(box s)

src/libcore/array/iter.rs

@@ -1,6 +1,5 @@
 //! Defines the `IntoIter` owned iterator for arrays.
 
-use super::LengthAtMost32;
 use crate::{
     fmt,
     iter::{ExactSizeIterator, FusedIterator, TrustedLen},
@@ -13,10 +12,7 @@ use crate::{
 ///
 /// [array]: ../../std/primitive.array.html
 #[unstable(feature = "array_value_iter", issue = "65798")]
-pub struct IntoIter<T, const N: usize>
-where
-    [T; N]: LengthAtMost32,
-{
+pub struct IntoIter<T, const N: usize> {
     /// This is the array we are iterating over.
     ///
     /// Elements with index `i` where `alive.start <= i < alive.end` have not
@@ -39,10 +35,7 @@ where
     alive: Range<usize>,
 }
 
-impl<T, const N: usize> IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> IntoIter<T, N> {
     /// Creates a new iterator over the given `array`.
     ///
     /// *Note*: this method might never get stabilized and/or removed in the
@@ -99,10 +92,7 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T, const N: usize> Iterator for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> Iterator for IntoIter<T, N> {
     type Item = T;
     fn next(&mut self) -> Option<Self::Item> {
         if self.alive.start == self.alive.end {
@@ -146,10 +136,7 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T, const N: usize> DoubleEndedIterator for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> DoubleEndedIterator for IntoIter<T, N> {
     fn next_back(&mut self) -> Option<Self::Item> {
         if self.alive.start == self.alive.end {
             return None;
@@ -182,10 +169,7 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T, const N: usize> Drop for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> Drop for IntoIter<T, N> {
     fn drop(&mut self) {
         // SAFETY: This is safe: `as_mut_slice` returns exactly the sub-slice
         // of elements that have not been moved out yet and that remain
@@ -195,10 +179,7 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T, const N: usize> ExactSizeIterator for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T, const N: usize> ExactSizeIterator for IntoIter<T, N> {
     fn len(&self) -> usize {
         // Will never underflow due to the invariant `alive.start <=
         // alive.end`.
@@ -210,20 +191,17 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T, const N: usize> FusedIterator for IntoIter<T, N> where [T; N]: LengthAtMost32 {}
+impl<T, const N: usize> FusedIterator for IntoIter<T, N> {}
 
 // The iterator indeed reports the correct length. The number of "alive"
 // elements (that will still be yielded) is the length of the range `alive`.
 // This range is decremented in length in either `next` or `next_back`. It is
 // always decremented by 1 in those methods, but only if `Some(_)` is returned.
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-unsafe impl<T, const N: usize> TrustedLen for IntoIter<T, N> where [T; N]: LengthAtMost32 {}
+unsafe impl<T, const N: usize> TrustedLen for IntoIter<T, N> {}
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T: Clone, const N: usize> Clone for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T: Clone, const N: usize> Clone for IntoIter<T, N> {
     fn clone(&self) -> Self {
         // SAFETY: each point of unsafety is documented inside the unsafe block
         unsafe {
@@ -249,10 +227,7 @@ where
 }
 
 #[stable(feature = "array_value_iter_impls", since = "1.40.0")]
-impl<T: fmt::Debug, const N: usize> fmt::Debug for IntoIter<T, N>
-where
-    [T; N]: LengthAtMost32,
-{
+impl<T: fmt::Debug, const N: usize> fmt::Debug for IntoIter<T, N> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Only print the elements that were not yielded yet: we cannot
         // access the yielded elements anymore.