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diff --git a/third_party/rust/objc/src/rc/mod.rs b/third_party/rust/objc/src/rc/mod.rs
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+/*!
+Utilities for reference counting Objective-C objects.
+
+The utilities of the `rc` module provide ARC-like semantics for working with
+Objective-C's reference counted objects in Rust.
+A `StrongPtr` retains an object and releases the object when dropped.
+A `WeakPtr` will not retain the object, but can be upgraded to a `StrongPtr`
+and safely fails if the object has been deallocated.
+
+These utilities are not intended to provide a fully safe interface, but can be
+useful when writing higher-level Rust wrappers for Objective-C code.
+
+For more information on Objective-C's reference counting, see Apple's documentation:
+<https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/MemoryMgmt.html>
+
+# Example
+
+``` no_run
+# #[macro_use] extern crate objc;
+# use objc::rc::{autoreleasepool, StrongPtr};
+# fn main() {
+// StrongPtr will release the object when dropped
+let obj = unsafe {
+    StrongPtr::new(msg_send![class!(NSObject), new])
+};
+
+// Cloning retains the object an additional time
+let cloned = obj.clone();
+autoreleasepool(|| {
+    // Autorelease consumes the StrongPtr, but won't
+    // actually release until the end of an autoreleasepool
+    cloned.autorelease();
+});
+
+// Weak references won't retain the object
+let weak = obj.weak();
+drop(obj);
+assert!(weak.load().is_null());
+# }
+```
+*/
+
+mod strong;
+mod weak;
+mod autorelease;
+
+pub use self::strong::StrongPtr;
+pub use self::weak::WeakPtr;
+pub use self::autorelease::autoreleasepool;
+
+// These tests use NSObject, which isn't present for GNUstep
+#[cfg(all(test, any(target_os = "macos", target_os = "ios")))]
+mod tests {
+    use runtime::Object;
+    use super::StrongPtr;
+    use super::autoreleasepool;
+
+    #[test]
+    fn test_strong_clone() {
+        fn retain_count(obj: *mut Object) -> usize {
+            unsafe { msg_send![obj, retainCount] }
+        }
+
+        let obj = unsafe {
+            StrongPtr::new(msg_send![class!(NSObject), new])
+        };
+        assert!(retain_count(*obj) == 1);
+
+        let cloned = obj.clone();
+        assert!(retain_count(*cloned) == 2);
+        assert!(retain_count(*obj) == 2);
+
+        drop(obj);
+        assert!(retain_count(*cloned) == 1);
+    }
+
+    #[test]
+    fn test_weak() {
+        let obj = unsafe {
+            StrongPtr::new(msg_send![class!(NSObject), new])
+        };
+        let weak = obj.weak();
+
+        let strong = weak.load();
+        assert!(*strong == *obj);
+        drop(strong);
+
+        drop(obj);
+        assert!(weak.load().is_null());
+    }
+
+    #[test]
+    fn test_weak_copy() {
+        let obj = unsafe {
+            StrongPtr::new(msg_send![class!(NSObject), new])
+        };
+        let weak = obj.weak();
+
+        let weak2 = weak.clone();
+        let strong = weak2.load();
+        assert!(*strong == *obj);
+    }
+
+    #[test]
+    fn test_autorelease() {
+        let obj = unsafe {
+            StrongPtr::new(msg_send![class!(NSObject), new])
+        };
+
+        fn retain_count(obj: *mut Object) -> usize {
+            unsafe { msg_send![obj, retainCount] }
+        }
+        let cloned = obj.clone();
+
+        autoreleasepool(|| {
+                        obj.autorelease();
+                        assert!(retain_count(*cloned) == 2);
+        });
+
+        // make sure that the autoreleased value has been released
+        assert!(retain_count(*cloned) == 1);
+    }
+}