Vec, VecDeque, RawVec etc. with COOP_PREFERRED. WIP: probably NOT compilable. Triggers an internal compiler error from cargo 1.68.0-nightly (f6e737b1e 2022-12-02)

Author: peter-lyons-kehl

library/alloc/src/boxed.rs

@@ -146,6 +146,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+use core::alloc;
 use core::any::Any;
 use core::async_iter::AsyncIterator;
 use core::borrow;
@@ -698,7 +699,7 @@ impl<T> Box<[T]> {
                 Err(_) => return Err(AllocError),
             };
             let ptr = Global.allocate(layout)?;
-            Ok(RawVec::from_raw_parts_in(ptr.as_mut_ptr() as *mut _, len, Global).into_box(len))
+            Ok(RawVec::<T, Global, false>::from_raw_parts_in(ptr.as_mut_ptr() as *mut _, len, Global).into_box(len))
         }
     }
 
@@ -730,12 +731,13 @@ impl<T> Box<[T]> {
                 Err(_) => return Err(AllocError),
             };
             let ptr = Global.allocate_zeroed(layout)?;
-            Ok(RawVec::from_raw_parts_in(ptr.as_mut_ptr() as *mut _, len, Global).into_box(len))
+            Ok(RawVec::<T, Global, false>::from_raw_parts_in(ptr.as_mut_ptr() as *mut _, len, Global).into_box(len))
         }
     }
 }
 
-impl<T, A: Allocator> Box<[T], A> {
+impl<T, A: Allocator> Box<[T], A>
+where [(); core::alloc::co_alloc_metadata_num_slots::<A>()]: {
     /// Constructs a new boxed slice with uninitialized contents in the provided allocator.
     ///
     /// # Examples
@@ -763,7 +765,7 @@ impl<T, A: Allocator> Box<[T], A> {
     // #[unstable(feature = "new_uninit", issue = "63291")]
     #[must_use]
     pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
-        unsafe { RawVec::with_capacity_in(len, alloc).into_box(len) }
+        unsafe { RawVec::<T, A, {alloc::SHORT_TERM_VEC_PREFERS_COOP}>::with_capacity_in(len, alloc).into_box(len) }
     }
 
     /// Constructs a new boxed slice with uninitialized contents in the provided allocator,
@@ -791,7 +793,7 @@ impl<T, A: Allocator> Box<[T], A> {
     // #[unstable(feature = "new_uninit", issue = "63291")]
     #[must_use]
     pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
-        unsafe { RawVec::with_capacity_zeroed_in(len, alloc).into_box(len) }
+        unsafe { RawVec::<T, A, {alloc::SHORT_TERM_VEC_PREFERS_COOP}>::with_capacity_zeroed_in(len, alloc).into_box(len) }
     }
 }
 
@@ -2019,7 +2021,8 @@ impl<I> FromIterator<I> for Box<[I]> {
 
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "box_slice_clone", since = "1.3.0")]
-impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A> {
+impl<T: Clone, A: Allocator + Clone> Clone for Box<[T], A>
+where [(); core::alloc::co_alloc_metadata_num_slots::<A>()]: {
     fn clone(&self) -> Self {
         let alloc = Box::allocator(self).clone();
         self.to_vec_in(alloc).into_boxed_slice()

library/alloc/src/collections/binary_heap.rs

@@ -143,12 +143,14 @@
 #![allow(missing_docs)]
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use core::fmt;
+use core::{alloc, fmt};
 use core::iter::{FromIterator, FusedIterator, InPlaceIterable, SourceIter, TrustedLen};
 use core::mem::{self, swap, ManuallyDrop};
 use core::ops::{Deref, DerefMut};
 use core::ptr;
 
+use crate::alloc::Global;
+
 use crate::collections::TryReserveError;
 use crate::slice;
 use crate::vec::{self, AsVecIntoIter, Vec};
@@ -1196,7 +1198,7 @@ impl<T> BinaryHeap<T> {
     /// ```
     #[inline]
     #[stable(feature = "drain", since = "1.6.0")]
-    pub fn drain(&mut self) -> Drain<'_, T> {
+    pub fn drain(&mut self) -> Drain<'_, T, {alloc::SHORT_TERM_VEC_PREFERS_COOP}> {
         Drain { iter: self.data.drain(..) }
     }
 
@@ -1476,12 +1478,14 @@ unsafe impl<T: Ord> TrustedLen for IntoIterSorted<T> {}
 /// [`drain`]: BinaryHeap::drain
 #[stable(feature = "drain", since = "1.6.0")]
 #[derive(Debug)]
-pub struct Drain<'a, T: 'a> {
-    iter: vec::Drain<'a, T>,
+pub struct Drain<'a, T: 'a, const COOP_PREFERRED: bool>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<Global>(COOP_PREFERRED)]: {
+    iter: vec::Drain<'a, T, Global, COOP_PREFERRED>,
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T> Iterator for Drain<'_, T> {
+impl<T, const COOP_PREFERRED: bool> Iterator for Drain<'_, T, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<Global>(COOP_PREFERRED)]: {
     type Item = T;
 
     #[inline]
@@ -1496,22 +1500,22 @@ impl<T> Iterator for Drain<'_, T> {
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T> DoubleEndedIterator for Drain<'_, T> {
+impl<T, const COOP_PREFERRED: bool> DoubleEndedIterator for Drain<'_, T, COOP_PREFERRED> {
     #[inline]
     fn next_back(&mut self) -> Option<T> {
         self.iter.next_back()
     }
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T> ExactSizeIterator for Drain<'_, T> {
+impl<T, const COOP_PREFERRED: bool> ExactSizeIterator for Drain<'_, T, COOP_PREFERRED> {
     fn is_empty(&self) -> bool {
         self.iter.is_empty()
     }
 }
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<T> FusedIterator for Drain<'_, T> {}
+impl<T, const COOP_PREFERRED: bool> FusedIterator for Drain<'_, T, COOP_PREFERRED> {}
 
 /// A draining iterator over the elements of a `BinaryHeap`.
 ///

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

@@ -19,11 +19,12 @@ pub struct Drain<
     'a,
     T: 'a,
     #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global,
+    const COOP_PREFERRED: bool = {alloc::SHORT_TERM_VEC_PREFERS_COOP}
 >
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     // We can't just use a &mut VecDeque<T, A>, as that would make Drain invariant over T
     // and we want it to be covariant instead
-    deque: NonNull<VecDeque<T, A>>,
+    deque: NonNull<VecDeque<T, A, COOP_PREFERRED>>,
     // drain_start is stored in deque.len
     drain_len: usize,
     // index into the logical array, not the physical one (always lies in [0..deque.len))
@@ -35,10 +36,10 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
     _marker: PhantomData<&'a T>,
 }
 
-impl<'a, T, A: Allocator> Drain<'a, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+impl<'a, T, A: Allocator, const COOP_PREFERRED: bool> Drain<'a, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     pub(super) unsafe fn new(
-        deque: &'a mut VecDeque<T, A>,
+        deque: &'a mut VecDeque<T, A, COOP_PREFERRED>,
         drain_start: usize,
         drain_len: usize,
     ) -> Self {
@@ -90,8 +91,8 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]
-impl<T: fmt::Debug, A: Allocator> fmt::Debug for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+impl<T: fmt::Debug, A: Allocator, const COOP_PREFERRED: bool> fmt::Debug for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple("Drain")
             .field(&self.drain_len)
@@ -103,21 +104,21 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-unsafe impl<T: Sync, A: Allocator + Sync> Sync for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {}
+unsafe impl<T: Sync, A: Allocator + Sync, const COOP_PREFERRED: bool> Sync for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {}
 #[stable(feature = "drain", since = "1.6.0")]
-unsafe impl<T: Send, A: Allocator + Send> Send for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {}
+unsafe impl<T: Send, A: Allocator + Send, const COOP_PREFERRED: bool> Send for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {}
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> Drop for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+impl<T, A: Allocator, const COOP_PREFERRED: bool> Drop for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     fn drop(&mut self) {
-        struct DropGuard<'r, 'a, T, A: Allocator> (&'r mut Drain<'a, T, A>)
-        where [(); alloc::co_alloc_metadata_num_slots::<A>()]:;
+        struct DropGuard<'r, 'a, T, A: Allocator, const COOP_PREFERRED: bool> (&'r mut Drain<'a, T, A, COOP_PREFERRED>)
+        where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]:;
 
-        impl<'r, 'a, T, A: Allocator> Drop for DropGuard<'r, 'a, T, A>
-        where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+        impl<'r, 'a, T, A: Allocator, const COOP_PREFERRED: bool> Drop for DropGuard<'r, 'a, T, A, COOP_PREFERRED>
+        where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
             fn drop(&mut self) {
                 if self.0.remaining != 0 {
                     unsafe {
@@ -198,8 +199,8 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> Iterator for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+impl<T, A: Allocator, const COOP_PREFERRED: bool> Iterator for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     type Item = T;
 
     #[inline]
@@ -221,8 +222,8 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> DoubleEndedIterator for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
+impl<T, A: Allocator, const COOP_PREFERRED: bool> DoubleEndedIterator for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {
     #[inline]
     fn next_back(&mut self) -> Option<T> {
         if self.remaining == 0 {
@@ -235,9 +236,9 @@ where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {
 }
 
 #[stable(feature = "drain", since = "1.6.0")]
-impl<T, A: Allocator> ExactSizeIterator for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {}
+impl<T, A: Allocator, const COOP_PREFERRED: bool> ExactSizeIterator for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {}
 
 #[stable(feature = "fused", since = "1.26.0")]
-impl<T, A: Allocator> FusedIterator for Drain<'_, T, A>
-where [(); alloc::co_alloc_metadata_num_slots::<A>()]: {}
+impl<T, A: Allocator, const COOP_PREFERRED: bool> FusedIterator for Drain<'_, T, A, COOP_PREFERRED>
+where [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]: {}

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

@@ -1,10 +1,10 @@
 macro_rules! __impl_slice_eq1 {
     ([$($vars:tt)*] $lhs:ty, $rhs:ty, $($constraints:tt)*) => {
         #[stable(feature = "vec_deque_partial_eq_slice", since = "1.17.0")]
-        impl<T, U, A: Allocator, $($vars)*> PartialEq<$rhs> for $lhs
+        impl<T, U, A: Allocator, const COOP_PREFERRED: bool, $($vars)*> PartialEq<$rhs> for $lhs
         where
             T: PartialEq<U>,
-            [(); core::alloc::co_alloc_metadata_num_slots::<A>()]:,
+            [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]:,
             $($constraints)*
         {
             fn eq(&self, other: &$rhs) -> bool {