Auto merge of #468 - JustForFun88:make_alloc_not_clone, r=Amanieu

Make allocator not `Clone`

`@Amanieu` Implements the idea proposed in #465 (comment). The `A: Allocator + Clone` requirement remains only for `Clone` implementations.

~~**The pull request is basically complete, just a final review (and maybe some tweaks if needed). Also, I haven't documented the functions yet. This can be done after the initial approval of this pull request.**~~

Main changes made:
1. Allacator moved from `RawTableInner` to `RawTable`;
2. `IS_ZERO_SIZED_TYPE` and `DATA_NEEDS_DROP` constants moved from separate structures to `SizedTypeProperties` trait;
3. For ease of implementation and avoidance of duplication, some functions are downgraded from `RawTable` to `RawTableInner`. These are: `with_capacity`, `iter`, `drop_elements`. Additionally, the `drop_inner_table` function has been created through which `impl Drop for RawTable<T, A>` is now implemented.

Author: bors

src/external_trait_impls/rayon/map.rs

@@ -232,11 +232,11 @@ impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValuesMut<'_, K, V> {
 /// [`into_par_iter`]: /hashbrown/struct.HashMap.html#method.into_par_iter
 /// [`HashMap`]: /hashbrown/struct.HashMap.html
 /// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
-pub struct IntoParIter<K, V, A: Allocator + Clone = Global> {
+pub struct IntoParIter<K, V, A: Allocator = Global> {
     inner: RawIntoParIter<(K, V), A>,
 }
 
-impl<K: Send, V: Send, A: Allocator + Clone + Send> ParallelIterator for IntoParIter<K, V, A> {
+impl<K: Send, V: Send, A: Allocator + Send> ParallelIterator for IntoParIter<K, V, A> {
     type Item = (K, V);
 
     #[cfg_attr(feature = "inline-more", inline)]
@@ -248,9 +248,7 @@ impl<K: Send, V: Send, A: Allocator + Clone + Send> ParallelIterator for IntoPar
     }
 }
 
-impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator + Clone> fmt::Debug
-    for IntoParIter<K, V, A>
-{
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<K, V, A> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         ParIter {
             inner: unsafe { self.inner.par_iter() },
@@ -267,11 +265,11 @@ impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator + Clone> fmt::Debug
 ///
 /// [`par_drain`]: /hashbrown/struct.HashMap.html#method.par_drain
 /// [`HashMap`]: /hashbrown/struct.HashMap.html
-pub struct ParDrain<'a, K, V, A: Allocator + Clone = Global> {
+pub struct ParDrain<'a, K, V, A: Allocator = Global> {
     inner: RawParDrain<'a, (K, V), A>,
 }
 
-impl<K: Send, V: Send, A: Allocator + Clone + Sync> ParallelIterator for ParDrain<'_, K, V, A> {
+impl<K: Send, V: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, K, V, A> {
     type Item = (K, V);
 
     #[cfg_attr(feature = "inline-more", inline)]
@@ -283,9 +281,7 @@ impl<K: Send, V: Send, A: Allocator + Clone + Sync> ParallelIterator for ParDrai
     }
 }
 
-impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator + Clone> fmt::Debug
-    for ParDrain<'_, K, V, A>
-{
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, K, V, A> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         ParIter {
             inner: unsafe { self.inner.par_iter() },
@@ -295,7 +291,7 @@ impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator + Clone> fmt::Debug
     }
 }
 
-impl<K: Sync, V: Sync, S, A: Allocator + Clone> HashMap<K, V, S, A> {
+impl<K: Sync, V: Sync, S, A: Allocator> HashMap<K, V, S, A> {
     /// Visits (potentially in parallel) immutably borrowed keys in an arbitrary order.
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn par_keys(&self) -> ParKeys<'_, K, V> {
@@ -315,7 +311,7 @@ impl<K: Sync, V: Sync, S, A: Allocator + Clone> HashMap<K, V, S, A> {
     }
 }
 
-impl<K: Send, V: Send, S, A: Allocator + Clone> HashMap<K, V, S, A> {
+impl<K: Send, V: Send, S, A: Allocator> HashMap<K, V, S, A> {
     /// Visits (potentially in parallel) mutably borrowed values in an arbitrary order.
     #[cfg_attr(feature = "inline-more", inline)]
     pub fn par_values_mut(&mut self) -> ParValuesMut<'_, K, V> {
@@ -340,7 +336,7 @@ where
     K: Eq + Hash + Sync,
     V: PartialEq + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     /// Returns `true` if the map is equal to another,
     /// i.e. both maps contain the same keys mapped to the same values.
@@ -354,9 +350,7 @@ where
     }
 }
 
-impl<K: Send, V: Send, S, A: Allocator + Clone + Send> IntoParallelIterator
-    for HashMap<K, V, S, A>
-{
+impl<K: Send, V: Send, S, A: Allocator + Send> IntoParallelIterator for HashMap<K, V, S, A> {
     type Item = (K, V);
     type Iter = IntoParIter<K, V, A>;
 
@@ -368,9 +362,7 @@ impl<K: Send, V: Send, S, A: Allocator + Clone + Send> IntoParallelIterator
     }
 }
 
-impl<'a, K: Sync, V: Sync, S, A: Allocator + Clone> IntoParallelIterator
-    for &'a HashMap<K, V, S, A>
-{
+impl<'a, K: Sync, V: Sync, S, A: Allocator> IntoParallelIterator for &'a HashMap<K, V, S, A> {
     type Item = (&'a K, &'a V);
     type Iter = ParIter<'a, K, V>;
 
@@ -383,9 +375,7 @@ impl<'a, K: Sync, V: Sync, S, A: Allocator + Clone> IntoParallelIterator
     }
 }
 
-impl<'a, K: Sync, V: Send, S, A: Allocator + Clone> IntoParallelIterator
-    for &'a mut HashMap<K, V, S, A>
-{
+impl<'a, K: Sync, V: Send, S, A: Allocator> IntoParallelIterator for &'a mut HashMap<K, V, S, A> {
     type Item = (&'a K, &'a mut V);
     type Iter = ParIterMut<'a, K, V>;
 
@@ -424,7 +414,7 @@ where
     K: Eq + Hash + Send,
     V: Send,
     S: BuildHasher,
-    A: Allocator + Clone,
+    A: Allocator,
 {
     fn par_extend<I>(&mut self, par_iter: I)
     where
@@ -440,7 +430,7 @@ where
     K: Copy + Eq + Hash + Sync,
     V: Copy + Sync,
     S: BuildHasher,
-    A: Allocator + Clone,
+    A: Allocator,
 {
     fn par_extend<I>(&mut self, par_iter: I)
     where
@@ -456,7 +446,7 @@ where
     K: Eq + Hash,
     S: BuildHasher,
     I: IntoParallelIterator,
-    A: Allocator + Clone,
+    A: Allocator,
     HashMap<K, V, S, A>: Extend<I::Item>,
 {
     let (list, len) = super::helpers::collect(par_iter);

src/external_trait_impls/rayon/raw.rs

@@ -75,18 +75,18 @@ impl<T> UnindexedProducer for ParIterProducer<T> {
 }
 
 /// Parallel iterator which consumes a table and returns elements.
-pub struct RawIntoParIter<T, A: Allocator + Clone = Global> {
+pub struct RawIntoParIter<T, A: Allocator = Global> {
     table: RawTable<T, A>,
 }
 
-impl<T, A: Allocator + Clone> RawIntoParIter<T, A> {
+impl<T, A: Allocator> RawIntoParIter<T, A> {
     #[cfg_attr(feature = "inline-more", inline)]
     pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
         self.table.par_iter()
     }
 }
 
-impl<T: Send, A: Allocator + Clone + Send> ParallelIterator for RawIntoParIter<T, A> {
+impl<T: Send, A: Allocator + Send> ParallelIterator for RawIntoParIter<T, A> {
     type Item = T;
 
     #[cfg_attr(feature = "inline-more", inline)]
@@ -108,23 +108,23 @@ impl<T: Send, A: Allocator + Clone + Send> ParallelIterator for RawIntoParIter<T
 }
 
 /// Parallel iterator which consumes elements without freeing the table storage.
-pub struct RawParDrain<'a, T, A: Allocator + Clone = Global> {
+pub struct RawParDrain<'a, T, A: Allocator = Global> {
     // We don't use a &'a mut RawTable<T> because we want RawParDrain to be
     // covariant over T.
     table: NonNull<RawTable<T, A>>,
     marker: PhantomData<&'a RawTable<T, A>>,
 }
 
-unsafe impl<T: Send, A: Allocator + Clone> Send for RawParDrain<'_, T, A> {}
+unsafe impl<T: Send, A: Allocator> Send for RawParDrain<'_, T, A> {}
 
-impl<T, A: Allocator + Clone> RawParDrain<'_, T, A> {
+impl<T, A: Allocator> RawParDrain<'_, T, A> {
     #[cfg_attr(feature = "inline-more", inline)]
     pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
         self.table.as_ref().par_iter()
     }
 }
 
-impl<T: Send, A: Allocator + Clone> ParallelIterator for RawParDrain<'_, T, A> {
+impl<T: Send, A: Allocator> ParallelIterator for RawParDrain<'_, T, A> {
     type Item = T;
 
     #[cfg_attr(feature = "inline-more", inline)]
@@ -142,7 +142,7 @@ impl<T: Send, A: Allocator + Clone> ParallelIterator for RawParDrain<'_, T, A> {
     }
 }
 
-impl<T, A: Allocator + Clone> Drop for RawParDrain<'_, T, A> {
+impl<T, A: Allocator> Drop for RawParDrain<'_, T, A> {
     fn drop(&mut self) {
         // If drive_unindexed is not called then simply clear the table.
         unsafe {
@@ -203,7 +203,7 @@ impl<T> Drop for ParDrainProducer<T> {
     }
 }
 
-impl<T, A: Allocator + Clone> RawTable<T, A> {
+impl<T, A: Allocator> RawTable<T, A> {
     /// Returns a parallel iterator over the elements in a `RawTable`.
     #[cfg_attr(feature = "inline-more", inline)]
     pub unsafe fn par_iter(&self) -> RawParIter<T> {

src/external_trait_impls/rayon/set.rs

@@ -16,11 +16,11 @@ use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, Pa
 /// [`into_par_iter`]: /hashbrown/struct.HashSet.html#method.into_par_iter
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
 /// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
-pub struct IntoParIter<T, A: Allocator + Clone = Global> {
+pub struct IntoParIter<T, A: Allocator = Global> {
     inner: map::IntoParIter<T, (), A>,
 }
 
-impl<T: Send, A: Allocator + Clone + Send> ParallelIterator for IntoParIter<T, A> {
+impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
     type Item = T;
 
     fn drive_unindexed<C>(self, consumer: C) -> C::Result
@@ -38,11 +38,11 @@ impl<T: Send, A: Allocator + Clone + Send> ParallelIterator for IntoParIter<T, A
 ///
 /// [`par_drain`]: /hashbrown/struct.HashSet.html#method.par_drain
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
-pub struct ParDrain<'a, T, A: Allocator + Clone = Global> {
+pub struct ParDrain<'a, T, A: Allocator = Global> {
     inner: map::ParDrain<'a, T, (), A>,
 }
 
-impl<T: Send, A: Allocator + Clone + Send + Sync> ParallelIterator for ParDrain<'_, T, A> {
+impl<T: Send, A: Allocator + Send + Sync> ParallelIterator for ParDrain<'_, T, A> {
     type Item = T;
 
     fn drive_unindexed<C>(self, consumer: C) -> C::Result
@@ -85,7 +85,7 @@ impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
 ///
 /// [`par_difference`]: /hashbrown/struct.HashSet.html#method.par_difference
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
-pub struct ParDifference<'a, T, S, A: Allocator + Clone = Global> {
+pub struct ParDifference<'a, T, S, A: Allocator = Global> {
     a: &'a HashSet<T, S, A>,
     b: &'a HashSet<T, S, A>,
 }
@@ -94,7 +94,7 @@ impl<'a, T, S, A> ParallelIterator for ParDifference<'a, T, S, A>
 where
     T: Eq + Hash + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     type Item = &'a T;
 
@@ -118,7 +118,7 @@ where
 ///
 /// [`par_symmetric_difference`]: /hashbrown/struct.HashSet.html#method.par_symmetric_difference
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
-pub struct ParSymmetricDifference<'a, T, S, A: Allocator + Clone = Global> {
+pub struct ParSymmetricDifference<'a, T, S, A: Allocator = Global> {
     a: &'a HashSet<T, S, A>,
     b: &'a HashSet<T, S, A>,
 }
@@ -127,7 +127,7 @@ impl<'a, T, S, A> ParallelIterator for ParSymmetricDifference<'a, T, S, A>
 where
     T: Eq + Hash + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     type Item = &'a T;
 
@@ -150,7 +150,7 @@ where
 ///
 /// [`par_intersection`]: /hashbrown/struct.HashSet.html#method.par_intersection
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
-pub struct ParIntersection<'a, T, S, A: Allocator + Clone = Global> {
+pub struct ParIntersection<'a, T, S, A: Allocator = Global> {
     a: &'a HashSet<T, S, A>,
     b: &'a HashSet<T, S, A>,
 }
@@ -159,7 +159,7 @@ impl<'a, T, S, A> ParallelIterator for ParIntersection<'a, T, S, A>
 where
     T: Eq + Hash + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     type Item = &'a T;
 
@@ -181,7 +181,7 @@ where
 ///
 /// [`par_union`]: /hashbrown/struct.HashSet.html#method.par_union
 /// [`HashSet`]: /hashbrown/struct.HashSet.html
-pub struct ParUnion<'a, T, S, A: Allocator + Clone = Global> {
+pub struct ParUnion<'a, T, S, A: Allocator = Global> {
     a: &'a HashSet<T, S, A>,
     b: &'a HashSet<T, S, A>,
 }
@@ -190,7 +190,7 @@ impl<'a, T, S, A> ParallelIterator for ParUnion<'a, T, S, A>
 where
     T: Eq + Hash + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     type Item = &'a T;
 
@@ -216,7 +216,7 @@ impl<T, S, A> HashSet<T, S, A>
 where
     T: Eq + Hash + Sync,
     S: BuildHasher + Sync,
-    A: Allocator + Clone + Sync,
+    A: Allocator + Sync,
 {
     /// Visits (potentially in parallel) the values representing the union,
     /// i.e. all the values in `self` or `other`, without duplicates.
@@ -289,7 +289,7 @@ where
 impl<T, S, A> HashSet<T, S, A>
 where
     T: Eq + Hash + Send,
-    A: Allocator + Clone + Send,
+    A: Allocator + Send,
 {
     /// Consumes (potentially in parallel) all values in an arbitrary order,
     /// while preserving the set's allocated memory for reuse.
@@ -301,7 +301,7 @@ where
     }
 }
 
-impl<T: Send, S, A: Allocator + Clone + Send> IntoParallelIterator for HashSet<T, S, A> {
+impl<T: Send, S, A: Allocator + Send> IntoParallelIterator for HashSet<T, S, A> {
     type Item = T;
     type Iter = IntoParIter<T, A>;
 
@@ -313,7 +313,7 @@ impl<T: Send, S, A: Allocator + Clone + Send> IntoParallelIterator for HashSet<T
     }
 }
 
-impl<'a, T: Sync, S, A: Allocator + Clone> IntoParallelIterator for &'a HashSet<T, S, A> {
+impl<'a, T: Sync, S, A: Allocator> IntoParallelIterator for &'a HashSet<T, S, A> {
     type Item = &'a T;
     type Iter = ParIter<'a, T>;
 
@@ -374,7 +374,7 @@ fn extend<T, S, I, A>(set: &mut HashSet<T, S, A>, par_iter: I)
 where
     T: Eq + Hash,
     S: BuildHasher,
-    A: Allocator + Clone,
+    A: Allocator,
     I: IntoParallelIterator,
     HashSet<T, S, A>: Extend<I::Item>,
 {