drain_filter feature flag

Cargo.toml

@@ -18,6 +18,7 @@ write = []
 union = []
 specialization = []
 may_dangle = []
+drain_filter = []
 
 # UNSTABLE FEATURES (requires Rust nightly)
 # Enable to use the #[debugger_visualizer] attribute.

src/lib.rs

@@ -410,6 +410,7 @@ impl<'a, T: 'a + Array> Drop for Drain<'a, T> {
     }
 }
 
+#[cfg(feature = "drain_filter")]
 /// An iterator which uses a closure to determine if an element should be removed.
 ///
 /// Returned from [`SmallVec::drain_filter`][1].
@@ -437,6 +438,7 @@ where
     panic_flag: bool,
 }
 
+#[cfg(feature = "drain_filter")]
 impl <T, F> fmt::Debug for DrainFilter<'_, T, F>
 where
     F: FnMut(&mut T::Item) -> bool,
@@ -448,6 +450,7 @@ where
     }
 }
 
+#[cfg(feature = "drain_filter")]
 impl <T, F> Iterator for DrainFilter<'_, T, F>
 where
     F: FnMut(&mut T::Item) -> bool,
@@ -487,6 +490,7 @@ where
     }
 }
 
+#[cfg(feature = "drain_filter")]
 impl <T, F> Drop for DrainFilter<'_, T, F>
 where
     F: FnMut(&mut T::Item) -> bool,
@@ -974,6 +978,8 @@ impl<A: Array> SmallVec<A> {
         }
     }
 
+
+    #[cfg(feature = "drain_filter")]
     /// Creates an iterator which uses a closure to determine if an element should be removed.
     /// 
     /// If the closure returns true, the element is removed and yielded. If the closure returns

src/tests.rs

@@ -990,10 +990,10 @@ fn test_size() {
     assert_eq!(24, size_of::<SmallVec<[u8; 8]>>());
 }
 
-// #[cfg(feature("drain_filter"))]
+#[cfg(feature = "drain_filter")]
 #[test]
 fn drain_filter() {
-    let mut a: SmallVec<[u8; 2]> = SmallVec::from_slice(&[1u8, 2, 3, 4, 5, 6, 7, 8]);
+    let mut a: SmallVec<[u8; 2]> = smallvec![1u8, 2, 3, 4, 5, 6, 7, 8];
 
     let b: SmallVec<[u8; 2]> = a.drain_filter(|x| *x % 3 == 0).collect();