From 1fa1dcca990d4e9d112f154c83802167f69f4fe9 Mon Sep 17 00:00:00 2001
From: Amanieu d'Antras <amanieu@gmail.com>
Date: Mon, 4 Mar 2024 17:38:02 +0000
Subject: [PATCH] Fix index calculation in panic guard of clone_from_impl

Previously, it was possible for an uninitialized element to be dropped
if all of the following occurred:
- `clone_from` was called where `T: !Copy`.
- The `clone` implementation of `T` panicked.
- The first bucket of the source `HashMap` contained an entry.
---
 src/raw/mod.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/raw/mod.rs b/src/raw/mod.rs
index ddd4fe7c1..22c01f5e9 100644
--- a/src/raw/mod.rs
+++ b/src/raw/mod.rs
@@ -3582,7 +3582,7 @@ impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
         // cloned so far.
         let mut guard = guard((0, &mut *self), |(index, self_)| {
             if T::NEEDS_DROP {
-                for i in 0..=*index {
+                for i in 0..*index {
                     if self_.is_bucket_full(i) {
                         self_.bucket(i).drop();
                     }
@@ -3596,7 +3596,7 @@ impl<T: Clone, A: Allocator + Clone> RawTable<T, A> {
             to.write(from.as_ref().clone());
 
             // Update the index in case we need to unwind.
-            guard.0 = index;
+            guard.0 = index + 1;
         }
 
         // Successfully cloned all items, no need to clean up.