Adding COOP_PREFERRED to Cow, ToOwned..

Author: peter-lyons-kehl

library/alloc/src/boxed.rs

@@ -780,10 +780,11 @@ where
     #[allow(unused_braces)]
     pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A>
     where
-    [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(SHORT_TERM_VEC_PREFERS_COOP!())]:,
+    // false = no need for co-alloc metadata, since it would get lost once converted to Box.
+    [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(false)]:,
     {
         unsafe {
-            RawVec::<T, A, { SHORT_TERM_VEC_PREFERS_COOP!() }>::with_capacity_in(len, alloc)
+            RawVec::<T, A, false>::with_capacity_in(len, alloc)
                 .into_box(len)
         }
     }
@@ -815,10 +816,11 @@ where
     #[allow(unused_braces)]
     pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A>
     where
-    [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(SHORT_TERM_VEC_PREFERS_COOP!())]:,
+    // false = no need for co-alloc metadata, since it would get lost once converted to Box.
+    [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(false)]:,
     {
         unsafe {
-            RawVec::<T, A, { SHORT_TERM_VEC_PREFERS_COOP!() }>::with_capacity_zeroed_in(
+            RawVec::<T, A, false>::with_capacity_zeroed_in(
                 len, alloc,
             )
             .into_box(len)

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

@@ -1406,7 +1406,6 @@ where
     pub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A, COOP_PREFERRED>
     where
         R: RangeBounds<usize>,
-        [(); alloc::co_alloc_metadata_num_slots_with_preference::<A>(SHORT_TERM_VEC_PREFERS_COOP!())]:,
     {
         // Memory safety
         //

library/alloc/src/vec/into_iter.rs

@@ -431,7 +431,13 @@ where
 {
     #[cfg(not(test))]
     fn clone(&self) -> Self {
-        self.as_slice().to_vec_in::<A, COOP_PREFERRED>(self.alloc.deref().clone()).into_iter()
+        // @FIXME Remove the following extras - used for type checks only
+        let slice = self.as_slice();
+        let vec: crate::vec::Vec<T, A, COOP_PREFERRED> = slice.to_vec_in::<A, COOP_PREFERRED>(self.alloc.deref().clone());
+        let _iter: IntoIter<T, A, COOP_PREFERRED> = vec.into_iter();
+
+        //self.as_slice().to_vec_in::<A, COOP_PREFERRED>(self.alloc.deref().clone()).into_iter()
+        loop {}
     }
     #[cfg(test)]
     fn clone(&self) -> Self {

library/alloc/src/vec/mod.rs

@@ -2065,8 +2065,6 @@ where
     pub fn drain<R>(&mut self, range: R) -> Drain<'_, T, A, COOP_PREFERRED>
     where
         R: RangeBounds<usize>,
-        [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(SHORT_TERM_VEC_PREFERS_COOP!())]:,
-
     {
         // Memory safety
         //
@@ -2893,8 +2891,6 @@ where
 impl<T, A: Allocator, const COOP_PREFERRED: bool> IntoIterator for Vec<T, A, COOP_PREFERRED>
 where
     [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]:,
-    [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(SHORT_TERM_VEC_PREFERS_COOP!())]:,
-
 {
     type Item = T;
     type IntoIter = IntoIter<T, A, COOP_PREFERRED>;

library/alloc/src/vec/splice.rs

@@ -26,7 +26,6 @@ pub struct Splice<
     const COOP_PREFERRED: bool = false
 > where
     [(); core::alloc::co_alloc_metadata_num_slots_with_preference::<A>(COOP_PREFERRED)]:,
-    //FIXME: If using SHORT_TERM_VEC_PREFERS_COOP!() instead of true, and the same for `drain` below, then this failed with: `derive` cannot be used on item swith type macros
 {
     pub(super) drain: Drain<'a, I::Item, A, COOP_PREFERRED>,
     pub(super) replace_with: I,