From 798c9cff1c9e85bbfbb41a0f80336b7391b41a45 Mon Sep 17 00:00:00 2001
From: "Tobin C. Harding" <me@tobin.cc>
Date: Fri, 30 Aug 2024 02:59:01 +1000
Subject: [PATCH 1/2] Fix bug in ArrayVec::extend_from_slice

Currently the source slice must be the exact length to fill the array to
max capacity, this is an unnecessary restriction since an `ArrayVec` is
a variable sized data structure.

Set the destination slice to be the same length as the source
slice (still maintain capacity checks).
---
 internals/src/array_vec.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/internals/src/array_vec.rs b/internals/src/array_vec.rs
index f75924ba1..8b6e54bf2 100644
--- a/internals/src/array_vec.rs
+++ b/internals/src/array_vec.rs
@@ -78,7 +78,7 @@ mod safety_boundary {
             assert!(new_len <= CAP, "buffer overflow");
             // SAFETY: MaybeUninit<T> has the same layout as T
             let slice = unsafe { &*(slice as *const _ as *const [MaybeUninit<T>]) };
-            self.data[self.len..].copy_from_slice(slice);
+            self.data[self.len..new_len].copy_from_slice(slice);
             self.len = new_len;
         }
     }

From 4024ba59103a84dcc94d3d2208f64b26ac478c0d Mon Sep 17 00:00:00 2001
From: "Tobin C. Harding" <me@tobin.cc>
Date: Fri, 30 Aug 2024 03:00:15 +1000
Subject: [PATCH 2/2] Add unit test for ArrayVec::extend_from_slice

Test that we can extend an `ArrayVec` with a slice that is less than
remaining capacity.
---
 internals/src/array_vec.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/internals/src/array_vec.rs b/internals/src/array_vec.rs
index 8b6e54bf2..b728503e8 100644
--- a/internals/src/array_vec.rs
+++ b/internals/src/array_vec.rs
@@ -181,4 +181,10 @@ mod tests {
         let mut av = ArrayVec::<_, 0>::new();
         av.extend_from_slice(&[42]);
     }
+
+    #[test]
+    fn extend_from_slice() {
+        let mut av = ArrayVec::<u8, 8>::new();
+        av.extend_from_slice(b"abc");
+    }
 }