1 files changed, 20 insertions, 12 deletions

diff --git a/third_party/rust/core-foundation/src/set.rs b/third_party/rust/core-foundation/src/set.rs
index eb1d357a03..641202de8d 100644
--- a/third_party/rust/core-foundation/src/set.rs
+++ b/third_party/rust/core-foundation/src/set.rs
@@ -9,13 +9,13 @@
 
 //! An immutable bag of elements.
 
+use core_foundation_sys::base::{kCFAllocatorDefault, CFRelease, CFTypeRef};
 pub use core_foundation_sys::set::*;
-use core_foundation_sys::base::{CFTypeRef, CFRelease, kCFAllocatorDefault};
 
-use base::{CFIndexConvertible, TCFType};
+use crate::base::{CFIndexConvertible, TCFType};
 
-use std::os::raw::c_void;
 use std::marker::PhantomData;
+use std::os::raw::c_void;
 
 /// An immutable bag of elements.
 pub struct CFSet<T = *const c_void>(CFSetRef, PhantomData<T>);
@@ -31,23 +31,31 @@ impl_CFTypeDescription!(CFSet);
 
 impl CFSet {
     /// Creates a new set from a list of `CFType` instances.
-    pub fn from_slice<T>(elems: &[T]) -> CFSet<T> where T: TCFType {
+    pub fn from_slice<T>(elems: &[T]) -> CFSet<T>
+    where
+        T: TCFType,
+    {
         unsafe {
             let elems: Vec<CFTypeRef> = elems.iter().map(|elem| elem.as_CFTypeRef()).collect();
-            let set_ref = CFSetCreate(kCFAllocatorDefault,
-                                      elems.as_ptr(),
-                                      elems.len().to_CFIndex(),
-                                      &kCFTypeSetCallBacks);
+            let set_ref = CFSetCreate(
+                kCFAllocatorDefault,
+                elems.as_ptr(),
+                elems.len().to_CFIndex(),
+                &kCFTypeSetCallBacks,
+            );
             TCFType::wrap_under_create_rule(set_ref)
         }
     }
 }
 
 impl<T> CFSet<T> {
-    /// Get the number of elements in the CFSet
+    /// Get the number of elements in the `CFSet`.
     pub fn len(&self) -> usize {
-        unsafe {
-            CFSetGetCount(self.0) as usize
-        }
+        unsafe { CFSetGetCount(self.0) as usize }
+    }
+
+    /// Returns `true` if the set contains no elements.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
     }
 }