VecDeque use cases have COOP_PREFERRED

Author: peter-lyons-kehl

library/alloc/src/collections/vec_deque/into_iter.rs

@@ -17,18 +17,19 @@ use super::VecDeque;
 pub struct IntoIter<
     T,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
+    const COOP_PREFERRED: bool = true
 >
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
-    inner: VecDeque<T, A>,
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
+    inner: VecDeque<T, A, COOP_PREFERRED>,
 }
 
-impl<T, A: Allocator> IntoIter<T, A>
+impl<T, A: Allocator, const COOP_PREFERRED: bool> IntoIter<T, A, COOP_PREFERRED>
 where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
-    pub(super) fn new(inner: VecDeque<T, A>) -> Self {
+    pub(super) fn new(inner: VecDeque<T, A, COOP_PREFERRED>) -> Self {
         IntoIter { inner }
     }
 
-    pub(super) fn into_vecdeque(self) -> VecDeque<T, A> {
+    pub(super) fn into_vecdeque(self) -> VecDeque<T, A, COOP_PREFERRED> {
         self.inner
     }
 }

library/alloc/src/collections/vec_deque/mod.rs

@@ -153,10 +153,10 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Default for VecDeque<T> {
+impl<T, const COOP_PREFERRED: bool = true> Default for VecDeque<T, Global, COOP_PREFERRED> {
     /// Creates an empty deque.
     #[inline]
-    fn default() -> VecDeque<T> {
+    fn default() -> VecDeque<T, Global, COOP_PREFERRED> {
         VecDeque::new()
     }
 }
@@ -536,7 +536,8 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
     }
 }
 
-impl<T> VecDeque<T> {
+impl<T,  Global, const COOP_PREFERRED: bool> VecDeque<T, Global, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     /// Creates an empty deque.
     ///
     /// # Examples
@@ -550,7 +551,7 @@ impl<T> VecDeque<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
-    pub fn new() -> VecDeque<T> {
+    pub fn new() -> VecDeque<T, Global, COOP_PREFERRED> {
         VecDeque::new_in(Global)
     }
 
@@ -566,7 +567,7 @@ impl<T> VecDeque<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
-    pub fn with_capacity(capacity: usize) -> VecDeque<T> {
+    pub fn with_capacity(capacity: usize) -> VecDeque<T, Global, COOP_PREFERRED> {
         Self::with_capacity_in(capacity, Global)
     }
 }
@@ -584,7 +585,7 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
     /// ```
     #[inline]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    pub const fn new_in(alloc: A) -> VecDeque<T, A> {
+    pub const fn new_in(alloc: A) -> VecDeque<T, A, COOP_PREFERRED> {
         VecDeque { head: 0, len: 0, buf: RawVec::new_in(alloc) }
     }
 
@@ -598,7 +599,7 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
     /// let deque: VecDeque<u32> = VecDeque::with_capacity(10);
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    pub fn with_capacity_in(capacity: usize, alloc: A) -> VecDeque<T, A> {
+    pub fn with_capacity_in(capacity: usize, alloc: A) -> VecDeque<T, A, COOP_PREFERRED> {
         VecDeque { head: 0, len: 0, buf: RawVec::with_capacity_in(capacity, alloc) }
     }
 
@@ -2889,7 +2890,7 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
     /// assert_eq!(vec, [8, 9, 1, 2, 3, 4]);
     /// assert_eq!(vec.as_ptr(), ptr);
     /// ```
-    fn from(mut other: VecDeque<T, A>) -> Self {
+    fn from<const _VECDEQUE_COOP_PREFERRED: bool>(mut other: VecDeque<T, A, _VECDEQUE_COOP_PREFERRED>) -> Self {
         other.make_contiguous();
 
         unsafe {
@@ -2902,6 +2903,7 @@ where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRE
             if other.head != 0 {
                 ptr::copy(buf.add(other.head), buf, len);
             }
+            // @TODO:
             Vec::from_raw_parts_in(buf, len, cap, alloc)
         }
     }

library/std/src/io/impls.rs

@@ -414,7 +414,8 @@ impl<A: Allocator> Write for Vec<u8, A> {
 
 /// Read is implemented for `VecDeque<u8>` by consuming bytes from the front of the `VecDeque`.
 #[stable(feature = "vecdeque_read_write", since = "1.63.0")]
-impl<A: Allocator> Read for VecDeque<u8, A> {
+impl<A: Allocator, const _COOP_PREFERRED: bool> Read for VecDeque<u8, A, _COOP_PREFERRED>
+where [(); co_alloc_metadata_num_slots_with_preference::<A>(_COOP_PREFERRED)]: {
     /// Fill `buf` with the contents of the "front" slice as returned by
     /// [`as_slices`][`VecDeque::as_slices`]. If the contained byte slices of the `VecDeque` are
     /// discontiguous, multiple calls to `read` will be needed to read the entire content.
@@ -438,7 +439,8 @@ impl<A: Allocator> Read for VecDeque<u8, A> {
 
 /// Write is implemented for `VecDeque<u8>` by appending to the `VecDeque`, growing it as needed.
 #[stable(feature = "vecdeque_read_write", since = "1.63.0")]
-impl<A: Allocator> Write for VecDeque<u8, A> {
+impl<A: Allocator, const _COOP_PREFERRED: bool> Write for VecDeque<u8, A, _COOP_PREFERRED>
+where [(); co_alloc_metadata_num_slots_with_preference::<A>(_COOP_PREFERRED)]: {
     #[inline]
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         self.extend(buf);