Fix `Vec::map_in_place` not doing what is written in the comment

1 files changed, 4 insertions, 1 deletions

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index 0e3799ed9ac..4a341898606 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1661,7 +1661,10 @@ impl<T> Vec<T> {
             // Create a `Vec` from our `PartialVecZeroSized` and make sure the
             // destructor of the latter will not run. None of this can panic.
             let mut result = Vec::new();
-            unsafe { result.set_len(pv.num_u); }
+            unsafe {
+                result.set_len(pv.num_u);
+                mem::forget(pv);
+            }
             result
         }
     }