Merge #7

7: Add IntoRawPtr and FromRawPtr impls for &T r=torkleyy a=dbkaplun



Co-authored-by: Dan Kaplun <[email protected]>

src/lib.rs

@@ -12,6 +12,7 @@
 //   See the License for the specific language governing permissions and
 //   limitations under the License.
 
+use std::cell::UnsafeCell;
 use std::fmt::{self, Debug, Formatter};
 use std::marker::PhantomData;
 use std::mem;
@@ -28,7 +29,7 @@ where
     P: IntoRawPtr + FromRawPtr,
 {
     inner: AtomicPtr<()>,
-    data: PhantomData<P>,
+    data: PhantomData<UnsafeCell<P>>,
 }
 
 impl<P> Debug for Atom<P>
@@ -147,12 +148,12 @@ where
 
 unsafe impl<P> Send for Atom<P>
 where
-    P: IntoRawPtr + FromRawPtr,
+    P: IntoRawPtr + FromRawPtr + Send,
 {
 }
 unsafe impl<P> Sync for Atom<P>
 where
-    P: IntoRawPtr + FromRawPtr,
+    P: IntoRawPtr + FromRawPtr + Send,
 {
 }
 
@@ -194,6 +195,21 @@ impl<T> FromRawPtr for Arc<T> {
     }
 }
 
+// This impl can be useful for stack-allocated and 'static values.
+impl<'a, T> IntoRawPtr for &'a T {
+    #[inline]
+    fn into_raw(self) -> *mut () {
+        self as *const _ as *mut ()
+    }
+}
+
+impl<'a, T> FromRawPtr for &'a T {
+    #[inline]
+    unsafe fn from_raw(ptr: *mut ()) -> &'a T {
+        &*(ptr as *mut T)
+    }
+}
+
 /// Transforms lifetime of the second pointer to match the first.
 #[inline]
 unsafe fn copy_lifetime<'a, S: ?Sized, T: ?Sized + 'a>(_ptr: &'a S, ptr: &T) -> &'a T {

tests/atom.rs

@@ -190,3 +190,10 @@ fn lifo_drop() {
     drop(atom);
     assert_eq!(2, v.load(Ordering::SeqCst));
 }
+
+#[test]
+fn borrow() {
+    let a = Atom::new(&5);
+    assert_eq!(a.swap(&7, Ordering::Relaxed), Some(&5));
+    assert_eq!(a.take(Ordering::Relaxed), Some(&7));
+}