Rollup merge of #28314 - tbu-:pr_atomics_are_send, r=brson

Author: steveklabnik

src/libcore/sync/atomic.rs

@@ -92,6 +92,7 @@ impl Default for AtomicBool {
     }
 }
 
+// Send is implicitly implemented for AtomicBool.
 unsafe impl Sync for AtomicBool {}
 
 /// A signed integer type which can be safely shared between threads.
@@ -106,6 +107,7 @@ impl Default for AtomicIsize {
     }
 }
 
+// Send is implicitly implemented for AtomicIsize.
 unsafe impl Sync for AtomicIsize {}
 
 /// An unsigned integer type which can be safely shared between threads.
@@ -120,6 +122,7 @@ impl Default for AtomicUsize {
     }
 }
 
+// Send is implicitly implemented for AtomicUsize.
 unsafe impl Sync for AtomicUsize {}
 
 /// A raw pointer type which can be safely shared between threads.

src/libcoretest/atomic.rs

@@ -10,6 +10,7 @@
 
 use core::sync::atomic::*;
 use core::sync::atomic::Ordering::SeqCst;
+use core::marker::{Send, Sync};
 
 #[test]
 fn bool_() {
@@ -82,3 +83,13 @@ fn static_init() {
     assert!(S_INT.load(SeqCst) == 0);
     assert!(S_UINT.load(SeqCst) == 0);
 }
+
+#[test]
+fn static_sync_and_send() {
+    fn ensure_sync_and_send<T:Sync+Send>() { }
+
+    ensure_sync_and_send::<AtomicBool>();
+    ensure_sync_and_send::<AtomicUsize>();
+    ensure_sync_and_send::<AtomicIsize>();
+    ensure_sync_and_send::<AtomicPtr>();
+}