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Revert "compiler/rustc_data_structures/src/sync/worker_local.rs: delete "unsafe impl Sync""

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This reverts commit 02406903b0.
This commit is contained in:
Askar Safin 2025-03-04 15:32:55 +03:00
parent fd17deacce
commit c6c4ea40dc
1 changed files with 6 additions and 5 deletions
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11
compiler/rustc_data_structures/src/sync/worker_local.rs
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@ -106,6 +106,12 @@ pub struct WorkerLocal<T> {
registry: Registry, registry: Registry,
} }
// This is safe because the `deref` call will return a reference to a `T` unique to each thread
// or it will panic for threads without an associated local. So there isn't a need for `T` to do
// it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
// can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
unsafe impl<T: Send> Sync for WorkerLocal<T> {}
impl<T> WorkerLocal<T> { impl<T> WorkerLocal<T> {
/// Creates a new worker local where the `initial` closure computes the /// Creates a new worker local where the `initial` closure computes the
/// value this worker local should take for each thread in the registry. /// value this worker local should take for each thread in the registry.
@ -132,11 +138,6 @@ impl<T> Deref for WorkerLocal<T> {
fn deref(&self) -> &T { fn deref(&self) -> &T {
// This is safe because `verify` will only return values less than // This is safe because `verify` will only return values less than
// `self.registry.thread_limit` which is the size of the `self.locals` array. // `self.registry.thread_limit` which is the size of the `self.locals` array.
// The `deref` call will return a reference to a `T` unique to each thread
// or it will panic for threads without an associated local. So there isn't a need for `T` to do
// it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
// can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
unsafe { &self.locals.get_unchecked(self.registry.id().verify()).0 } unsafe { &self.locals.get_unchecked(self.registry.id().verify()).0 }
} }
} }