Fix loom tests

src/lib.rs

@@ -140,6 +140,13 @@ impl<T> ConcurrentQueue<T> {
     ///
     /// let q = ConcurrentQueue::<i32>::unbounded();
     /// ```
+    #[cfg(not(loom))]
+    pub const fn unbounded() -> ConcurrentQueue<T> {
+        ConcurrentQueue(Inner::Unbounded(Unbounded::new()))
+    }
+
+    // Loom's primitives are not const constructible.
+    #[cfg(loom)]
     pub const fn unbounded() -> ConcurrentQueue<T> {
         ConcurrentQueue(Inner::Unbounded(Unbounded::new()))
     }

src/unbounded.rs

@@ -149,6 +149,7 @@ pub struct Unbounded<T> {
 
 impl<T> Unbounded<T> {
     /// Creates a new unbounded queue.
+    #[cfg(not(loom))]
     pub const fn new() -> Unbounded<T> {
         Unbounded {
             head: CachePadded::new(Position {
@@ -162,6 +163,21 @@ impl<T> Unbounded<T> {
         }
     }
 
+    // Loom's AtomicPtrs are not const constructible.
+    #[cfg(loom)]
+    pub fn new() -> Unbounded<T> {
+        Unbounded {
+            head: CachePadded::new(Position {
+                block: AtomicPtr::new(ptr::null_mut()),
+                index: AtomicUsize::new(0),
+            }),
+            tail: CachePadded::new(Position {
+                block: AtomicPtr::new(ptr::null_mut()),
+                index: AtomicUsize::new(0),
+            }),
+        }
+    }
+
     /// Pushes an item into the queue.
     pub fn push(&self, value: T) -> Result<(), PushError<T>> {
         let mut tail = self.tail.index.load(Ordering::Acquire);