From ed9f23cb10b4964e6d7912e77b763980ca2aa833 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Tue, 25 Oct 2022 21:34:41 +0900
Subject: [PATCH] Do not copy data before dropping

---
 src/once_cell.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/once_cell.rs b/src/once_cell.rs
index 079b9b4..463dc62 100644
--- a/src/once_cell.rs
+++ b/src/once_cell.rs
@@ -749,7 +749,11 @@ impl<T: fmt::Debug> fmt::Debug for OnceCell<T> {
 
 impl<T> Drop for OnceCell<T> {
     fn drop(&mut self) {
-        drop(self.take());
+        if State::from(*self.state.get_mut()) == State::Initialized {
+            // SAFETY: We know that the value is initialized, so it is safe to
+            // drop it.
+            unsafe { self.value.get().cast::<T>().drop_in_place() }
+        }
     }
 }