Trait sp_std::marker::Sync

1.0.0 · source ·
pub unsafe auto trait Sync { }
Expand description

Types for which it is safe to share references between threads.

This trait is automatically implemented when the compiler determines it’s appropriate.

The precise definition is: a type T is Sync if and only if &T is Send. In other words, if there is no possibility of undefined behavior (including data races) when passing &T references between threads.

As one would expect, primitive types like u8 and f64 are all Sync, and so are simple aggregate types containing them, like tuples, structs and enums. More examples of basic Sync types include “immutable” types like &T, and those with simple inherited mutability, such as Box<T>, Vec<T> and most other collection types. (Generic parameters need to be Sync for their container to be Sync.)

A somewhat surprising consequence of the definition is that &mut T is Sync (if T is Sync) even though it seems like that might provide unsynchronized mutation. The trick is that a mutable reference behind a shared reference (that is, & &mut T) becomes read-only, as if it were a & &T. Hence there is no risk of a data race.

A shorter overview of how Sync and Send relate to referencing:

  • &T is Send if and only if T is Sync
  • &mut T is Send if and only if T is Send
  • &T and &mut T are Sync if and only if T is Sync

Types that are not Sync are those that have “interior mutability” in a non-thread-safe form, such as Cell and RefCell. These types allow for mutation of their contents even through an immutable, shared reference. For example the set method on Cell<T> takes &self, so it requires only a shared reference &Cell<T>. The method performs no synchronization, thus Cell cannot be Sync.

Another example of a non-Sync type is the reference-counting pointer Rc. Given any reference &Rc<T>, you can clone a new Rc<T>, modifying the reference counts in a non-atomic way.

For cases when one does need thread-safe interior mutability, Rust provides atomic data types, as well as explicit locking via sync::Mutex and sync::RwLock. These types ensure that any mutation cannot cause data races, hence the types are Sync. Likewise, sync::Arc provides a thread-safe analogue of Rc.

Any types with interior mutability must also use the cell::UnsafeCell wrapper around the value(s) which can be mutated through a shared reference. Failing to doing this is undefined behavior. For example, transmute-ing from &T to &mut T is invalid.

See the Nomicon for more details about Sync.

Implementors§

1.26.0 · source§

impl !Sync for Args

1.26.0 · source§

impl !Sync for ArgsOs

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impl Sync for AtomicBool

1.34.0 · source§

impl Sync for AtomicI8

1.34.0 · source§

impl Sync for AtomicI16

1.34.0 · source§

impl Sync for AtomicI32

1.34.0 · source§

impl Sync for AtomicI64

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impl Sync for AtomicIsize

1.34.0 · source§

impl Sync for AtomicU8

1.34.0 · source§

impl Sync for AtomicU16

1.34.0 · source§

impl Sync for AtomicU32

1.34.0 · source§

impl Sync for AtomicU64

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impl Sync for AtomicUsize

1.6.0 · source§

impl Sync for alloc::string::Drain<'_>

1.36.0 · source§

impl Sync for Waker

1.44.0 · source§

impl<'a> Sync for IoSlice<'a>

1.44.0 · source§

impl<'a> Sync for IoSliceMut<'a>

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impl<Dyn> Sync for DynMetadata<Dyn>
where Dyn: ?Sized,

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impl<T> !Sync for *const T
where T: ?Sized,

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impl<T> !Sync for *mut T
where T: ?Sized,

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impl<T> !Sync for Cell<T>
where T: ?Sized,

1.70.0 · source§

impl<T> !Sync for OnceCell<T>

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impl<T> !Sync for RefCell<T>
where T: ?Sized,

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impl<T> !Sync for UnsafeCell<T>
where T: ?Sized,

1.25.0 · source§

impl<T> !Sync for NonNull<T>
where T: ?Sized,

NonNull pointers are not Sync because the data they reference may be aliased.

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impl<T> !Sync for Receiver<T>

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impl<T> Sync for ThinBox<T>
where T: Sync + ?Sized,

ThinBox<T> is Sync if T is Sync because the data is owned.

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impl<T> Sync for SyncUnsafeCell<T>
where T: Sync + ?Sized,

1.31.0 · source§

impl<T> Sync for ChunksExactMut<'_, T>
where T: Sync,

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impl<T> Sync for ChunksMut<'_, T>
where T: Sync,

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impl<T> Sync for sp_std::slice::Iter<'_, T>
where T: Sync,

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impl<T> Sync for sp_std::slice::IterMut<'_, T>
where T: Sync,

1.31.0 · source§

impl<T> Sync for RChunksExactMut<'_, T>
where T: Sync,

1.31.0 · source§

impl<T> Sync for RChunksMut<'_, T>
where T: Sync,

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impl<T> Sync for AtomicPtr<T>

1.72.0 · source§

impl<T> Sync for Sender<T>
where T: Send,

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impl<T> Sync for Exclusive<T>
where T: ?Sized,

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impl<T> Sync for Mutex<T>
where T: Send + ?Sized,

1.19.0 · source§

impl<T> Sync for MutexGuard<'_, T>
where T: Sync + ?Sized,

1.70.0 · source§

impl<T> Sync for OnceLock<T>
where T: Sync + Send,

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impl<T> Sync for RwLock<T>
where T: Send + Sync + ?Sized,

1.23.0 · source§

impl<T> Sync for RwLockReadGuard<'_, T>
where T: Sync + ?Sized,

1.23.0 · source§

impl<T> Sync for RwLockWriteGuard<'_, T>
where T: Sync + ?Sized,

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impl<T> Sync for alloc::collections::linked_list::Iter<'_, T>
where T: Sync,

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impl<T> Sync for alloc::collections::linked_list::IterMut<'_, T>
where T: Sync,

1.29.0 · source§

impl<T> Sync for JoinHandle<T>

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impl<T, A> !Sync for Rc<T, A>
where A: Allocator, T: ?Sized,

1.4.0 · source§

impl<T, A> !Sync for sp_std::rc::Weak<T, A>
where A: Allocator, T: ?Sized,

1.6.0 · source§

impl<T, A> Sync for sp_std::collections::vec_deque::Drain<'_, T, A>
where T: Sync, A: Allocator + Sync,

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impl<T, A> Sync for Arc<T, A>
where T: Sync + Send + ?Sized, A: Allocator + Sync,

1.4.0 · source§

impl<T, A> Sync for sp_std::sync::Weak<T, A>
where T: Sync + Send + ?Sized, A: Allocator + Sync,

1.6.0 · source§

impl<T, A> Sync for sp_std::vec::Drain<'_, T, A>
where T: Sync, A: Sync + Allocator,

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impl<T, A> Sync for sp_std::vec::IntoIter<T, A>
where T: Sync, A: Allocator + Sync,

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impl<T, A> Sync for alloc::collections::linked_list::Cursor<'_, T, A>
where T: Sync, A: Allocator + Sync,

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impl<T, A> Sync for alloc::collections::linked_list::CursorMut<'_, T, A>
where T: Sync, A: Allocator + Sync,

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impl<T, A> Sync for LinkedList<T, A>
where T: Sync, A: Allocator + Sync,

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impl<T, F> Sync for LazyLock<T, F>
where T: Sync + Send, F: Send,

Auto implementors§

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impl !Sync for OnceState

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impl Sync for sp_std::cmp::Ordering

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impl Sync for Infallible

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impl Sync for sp_std::fmt::Alignment

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impl Sync for FpCategory

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impl Sync for IntErrorKind

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impl Sync for SearchStep

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impl Sync for sp_std::sync::atomic::Ordering

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impl Sync for RecvTimeoutError

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impl Sync for TryRecvError

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impl Sync for AllocError

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impl Sync for Global

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impl Sync for Layout

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impl Sync for LayoutError

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impl Sync for System

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impl Sync for TypeId

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impl Sync for BorrowError

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impl Sync for BorrowMutError

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impl Sync for Error

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impl Sync for DefaultHasher

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impl Sync for RandomState

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impl Sync for SipHasher

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impl Sync for Assume

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impl Sync for NonZeroI8

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impl Sync for NonZeroI16

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impl Sync for NonZeroI32

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impl Sync for NonZeroI64

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impl Sync for NonZeroI128

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impl Sync for NonZeroIsize

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impl Sync for NonZeroU8

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impl Sync for NonZeroU16

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impl Sync for NonZeroU32

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impl Sync for NonZeroU64

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impl Sync for NonZeroU128

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impl Sync for NonZeroUsize

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impl Sync for ParseFloatError

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impl Sync for ParseIntError

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impl Sync for TryFromIntError

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impl Sync for RangeFull

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impl Sync for sp_std::ptr::Alignment

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impl Sync for ParseBoolError

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impl Sync for Utf8Error

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impl Sync for Writer

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impl Sync for RecvError

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impl Sync for Barrier

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impl Sync for BarrierWaitResult

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impl Sync for Condvar

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impl Sync for sp_std::sync::Once

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impl Sync for WaitTimeoutResult

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impl Sync for Duration

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impl Sync for TryFromFloatSecsError

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impl Sync for PhantomPinned

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impl<'a> !Sync for Arguments<'a>

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impl<'a> !Sync for Formatter<'a>

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impl<'a> Sync for EscapeAscii<'a>

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impl<'a> Sync for CharSearcher<'a>

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impl<'a> Sync for Bytes<'a>

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impl<'a> Sync for CharIndices<'a>

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impl<'a> Sync for Chars<'a>

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impl<'a> Sync for EncodeUtf16<'a>

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impl<'a> Sync for EscapeDebug<'a>

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impl<'a> Sync for EscapeDefault<'a>

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impl<'a> Sync for EscapeUnicode<'a>

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impl<'a> Sync for Lines<'a>

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impl<'a> Sync for LinesAny<'a>

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impl<'a> Sync for SplitAsciiWhitespace<'a>

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impl<'a> Sync for SplitWhitespace<'a>

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impl<'a> Sync for Utf8Chunk<'a>

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impl<'a> Sync for Utf8Chunks<'a>

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impl<'a, 'b> !Sync for DebugList<'a, 'b>

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impl<'a, 'b> !Sync for DebugMap<'a, 'b>

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impl<'a, 'b> !Sync for DebugSet<'a, 'b>

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impl<'a, 'b> !Sync for DebugStruct<'a, 'b>

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impl<'a, 'b> !Sync for DebugTuple<'a, 'b>

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impl<'a, 'b> Sync for CharSliceSearcher<'a, 'b>

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impl<'a, 'b> Sync for StrSearcher<'a, 'b>

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impl<'a, 'b, const N: usize> Sync for CharArrayRefSearcher<'a, 'b, N>

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impl<'a, B: ?Sized> Sync for Cow<'a, B>
where B: Sync, <B as ToOwned>::Owned: Sync,

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impl<'a, F> Sync for CharPredicateSearcher<'a, F>
where F: Sync,

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impl<'a, I> Sync for ByRefSized<'a, I>
where I: Sync,

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impl<'a, I, A> Sync for Splice<'a, I, A>
where A: Sync, I: Sync, <I as Iterator>::Item: Sync,

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impl<'a, K, V> Sync for sp_std::collections::btree_map::Cursor<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for sp_std::collections::btree_map::Iter<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for sp_std::collections::btree_map::IterMut<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for Keys<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for sp_std::collections::btree_map::Range<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for RangeMut<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for Values<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V> Sync for ValuesMut<'a, K, V>
where K: Sync, V: Sync,

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impl<'a, K, V, A> Sync for Entry<'a, K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, A> Sync for sp_std::collections::btree_map::CursorMut<'a, K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, A> Sync for OccupiedEntry<'a, K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, A> Sync for OccupiedError<'a, K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, A> Sync for VacantEntry<'a, K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, F, A> Sync for sp_std::collections::btree_map::ExtractIf<'a, K, V, F, A>
where A: Sync, F: Sync, K: Sync, V: Sync,

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impl<'a, P> Sync for MatchIndices<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for Matches<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for RMatchIndices<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for RMatches<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for sp_std::str::RSplit<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for sp_std::str::RSplitN<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for RSplitTerminator<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for sp_std::str::Split<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for sp_std::str::SplitInclusive<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for sp_std::str::SplitN<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, P> Sync for SplitTerminator<'a, P>
where <P as Pattern<'a>>::Searcher: Sync,

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impl<'a, T> !Sync for sp_std::sync::mpsc::Iter<'a, T>

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impl<'a, T> !Sync for TryIter<'a, T>

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impl<'a, T> Sync for sp_std::collections::btree_set::Iter<'a, T>
where T: Sync,

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impl<'a, T> Sync for sp_std::collections::btree_set::Range<'a, T>
where T: Sync,

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impl<'a, T> Sync for SymmetricDifference<'a, T>
where T: Sync,

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impl<'a, T> Sync for Union<'a, T>
where T: Sync,

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impl<'a, T> Sync for sp_std::collections::vec_deque::Iter<'a, T>
where T: Sync,

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impl<'a, T> Sync for sp_std::collections::vec_deque::IterMut<'a, T>
where T: Sync,

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impl<'a, T> Sync for sp_std::result::Iter<'a, T>
where T: Sync,

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impl<'a, T> Sync for sp_std::result::IterMut<'a, T>
where T: Sync,

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impl<'a, T> Sync for Chunks<'a, T>
where T: Sync,

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impl<'a, T> Sync for ChunksExact<'a, T>
where T: Sync,

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impl<'a, T> Sync for RChunks<'a, T>
where T: Sync,

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impl<'a, T> Sync for RChunksExact<'a, T>
where T: Sync,

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impl<'a, T> Sync for Windows<'a, T>
where T: Sync,

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impl<'a, T, A> Sync for Difference<'a, T, A>
where A: Sync, T: Sync,

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impl<'a, T, A> Sync for Intersection<'a, T, A>
where A: Sync, T: Sync,

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impl<'a, T, F, A> Sync for sp_std::collections::btree_set::ExtractIf<'a, T, F, A>
where A: Sync, F: Sync, T: Sync,

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impl<'a, T, F, A> Sync for sp_std::vec::ExtractIf<'a, T, F, A>
where A: Sync, F: Sync, T: Sync,

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impl<'a, T, P> Sync for GroupBy<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for GroupByMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for sp_std::slice::RSplit<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for RSplitMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for sp_std::slice::RSplitN<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for RSplitNMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for sp_std::slice::Split<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for sp_std::slice::SplitInclusive<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for SplitInclusiveMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for SplitMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for sp_std::slice::SplitN<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, P> Sync for SplitNMut<'a, T, P>
where P: Sync, T: Sync,

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impl<'a, T, const N: usize> !Sync for ArrayWindows<'a, T, N>

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impl<'a, T, const N: usize> Sync for sp_std::slice::ArrayChunks<'a, T, N>
where T: Sync,

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impl<'a, T, const N: usize> Sync for ArrayChunksMut<'a, T, N>
where T: Sync,

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impl<'a, const N: usize> Sync for CharArraySearcher<'a, N>

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impl<'b, T> !Sync for Ref<'b, T>

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impl<'b, T> !Sync for RefMut<'b, T>

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impl<A> Sync for Repeat<A>
where A: Sync,

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impl<A, B> Sync for Chain<A, B>
where A: Sync, B: Sync,

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impl<A, B> Sync for Zip<A, B>
where A: Sync, B: Sync,

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impl<B, C> Sync for ControlFlow<B, C>
where B: Sync, C: Sync,

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impl<F> Sync for FormatterFn<F>
where F: Sync,

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impl<F> Sync for FromFn<F>
where F: Sync,

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impl<F> Sync for OnceWith<F>
where F: Sync,

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impl<F> Sync for RepeatWith<F>
where F: Sync,

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impl<H> Sync for BuildHasherDefault<H>

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impl<I> Sync for Cloned<I>
where I: Sync,

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impl<I> Sync for Copied<I>
where I: Sync,

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impl<I> Sync for Cycle<I>
where I: Sync,

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impl<I> Sync for Enumerate<I>
where I: Sync,

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impl<I> Sync for Flatten<I>
where I: Sync, <<I as Iterator>::Item as IntoIterator>::IntoIter: Sync,

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impl<I> Sync for Fuse<I>
where I: Sync,

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impl<I> Sync for Intersperse<I>
where I: Sync, <I as Iterator>::Item: Sync,

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impl<I> Sync for Peekable<I>
where I: Sync, <I as Iterator>::Item: Sync,

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impl<I> Sync for Skip<I>
where I: Sync,

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impl<I> Sync for StepBy<I>
where I: Sync,

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impl<I> Sync for Take<I>
where I: Sync,

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impl<I, F> Sync for FilterMap<I, F>
where F: Sync, I: Sync,

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impl<I, F> Sync for Inspect<I, F>
where F: Sync, I: Sync,

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impl<I, F> Sync for Map<I, F>
where F: Sync, I: Sync,

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impl<I, F, const N: usize> Sync for MapWindows<I, F, N>
where F: Sync, I: Sync, <I as Iterator>::Item: Sync,

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impl<I, G> Sync for IntersperseWith<I, G>
where G: Sync, I: Sync, <I as Iterator>::Item: Sync,

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impl<I, P> Sync for Filter<I, P>
where I: Sync, P: Sync,

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impl<I, P> Sync for MapWhile<I, P>
where I: Sync, P: Sync,

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impl<I, P> Sync for SkipWhile<I, P>
where I: Sync, P: Sync,

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impl<I, P> Sync for TakeWhile<I, P>
where I: Sync, P: Sync,

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impl<I, St, F> Sync for Scan<I, St, F>
where F: Sync, I: Sync, St: Sync,

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impl<I, U, F> Sync for FlatMap<I, U, F>
where F: Sync, I: Sync, <U as IntoIterator>::IntoIter: Sync,

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impl<I, const N: usize> Sync for sp_std::iter::ArrayChunks<I, N>
where I: Sync, <I as Iterator>::Item: Sync,

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impl<Idx> Sync for sp_std::ops::Range<Idx>
where Idx: Sync,

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impl<Idx> Sync for RangeFrom<Idx>
where Idx: Sync,

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impl<Idx> Sync for RangeInclusive<Idx>
where Idx: Sync,

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impl<Idx> Sync for RangeTo<Idx>
where Idx: Sync,

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impl<Idx> Sync for RangeToInclusive<Idx>
where Idx: Sync,

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impl<K, V, A> Sync for BTreeMap<K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<K, V, A> Sync for sp_std::collections::btree_map::IntoIter<K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<K, V, A> Sync for IntoKeys<K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<K, V, A> Sync for IntoValues<K, V, A>
where A: Sync, K: Sync, V: Sync,

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impl<T> !Sync for UniqueRc<T>

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impl<T> !Sync for sp_std::sync::mpsc::IntoIter<T>

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impl<T> Sync for Bound<T>
where T: Sync,

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impl<T> Sync for TryLockError<T>
where T: Sync,

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impl<T> Sync for TrySendError<T>
where T: Sync,

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impl<T> Sync for Reverse<T>
where T: Sync,

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impl<T> Sync for Empty<T>

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impl<T> Sync for sp_std::iter::Once<T>
where T: Sync,

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impl<T> Sync for Rev<T>
where T: Sync,

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impl<T> Sync for Discriminant<T>

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impl<T> Sync for Saturating<T>
where T: Sync,

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impl<T> Sync for Wrapping<T>
where T: Sync,

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impl<T> Sync for Yeet<T>
where T: Sync,

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impl<T> Sync for sp_std::result::IntoIter<T>
where T: Sync,

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impl<T> Sync for SendError<T>
where T: Sync,

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impl<T> Sync for SyncSender<T>
where T: Send,

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impl<T> Sync for PoisonError<T>
where T: Sync,

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impl<T> Sync for MaybeUninit<T>
where T: Sync,

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impl<T, A> Sync for BTreeSet<T, A>
where A: Sync, T: Sync,

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impl<T, A> Sync for sp_std::collections::btree_set::IntoIter<T, A>
where A: Sync, T: Sync,

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impl<T, A> Sync for sp_std::collections::vec_deque::IntoIter<T, A>
where A: Sync, T: Sync,

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impl<T, A> Sync for VecDeque<T, A>
where A: Sync, T: Sync,

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impl<T, A> Sync for Vec<T, A>
where A: Sync, T: Sync,

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impl<T, E> Sync for Result<T, E>
where E: Sync, T: Sync,

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impl<T, F = fn() -> T> !Sync for LazyCell<T, F>

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impl<T, F> Sync for Successors<T, F>
where F: Sync, T: Sync,

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impl<T: ?Sized> Sync for ManuallyDrop<T>
where T: Sync,

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impl<T: ?Sized> Sync for PhantomData<T>
where T: Sync,

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impl<T: ?Sized, A> Sync for Box<T, A>
where A: Sync, T: Sync,

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impl<Y, R> Sync for CoroutineState<Y, R>
where R: Sync, Y: Sync,