Merge remote-tracking branch 'upstream/master'

[rust.git] / src / librustc_data_structures / thin_vec.rs

diff --git a/src/librustc_data_structures/thin_vec.rs b/src/librustc_data_structures/thin_vec.rs
index 359f9b7842da3775cc735bd35e326231ff9a2ee7..ed57c528f51e0de03b0c85741457a3c2c17334e6 100644 (file)
--- a/src/librustc_data_structures/thin_vec.rs
+++ b/src/librustc_data_structures/thin_vec.rs
@@ -39,6 +39,15 @@ fn deref(&self) -> &[T] {
     }
 }
 
+impl<T> ::std::ops::DerefMut for ThinVec<T> {
+    fn deref_mut(&mut self) -> &mut [T] {
+        match *self {
+            ThinVec(None) => &mut [],
+            ThinVec(Some(ref mut vec)) => vec,
+        }
+    }
+}
+
 impl<T> Extend<T> for ThinVec<T> {
     fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
         match *self {