auto merge of #18908 : tbu-/rust/pr_mapinplace_fixzerosized, r=alexcrichton

1 files changed, 4 insertions, 1 deletions

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index d6a21ef19a2..0777a1a128f 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1647,7 +1647,10 @@ 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
         }
     }