From c61daf69ed5303ab264e1a92df3d20886e951f50 Mon Sep 17 00:00:00 2001
From: Daniel Knopik <daniel@dknopik.de>
Date: Fri, 24 Apr 2026 16:46:21 +0200
Subject: [PATCH] Add clone_zeroed

---
 ssz/src/bitfield.rs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/ssz/src/bitfield.rs b/ssz/src/bitfield.rs
index e3b1e02..ef7bd76 100644
--- a/ssz/src/bitfield.rs
+++ b/ssz/src/bitfield.rs
@@ -275,6 +275,13 @@ impl<N: Unsigned + Clone> Bitfield<Variable<N>> {
 
         Ok(resized)
     }
+
+    /// Returns a clone of the bitfield with all bits set to false.
+    ///
+    /// Compared to `with_capacity`, this is infallible.
+    pub fn clone_zeroed(&self) -> Self {
+        Self::with_capacity(self.len()).expect("`len` is guaranteed to be `N` or less")
+    }
 }
 
 impl<N: Unsigned + Clone> Bitfield<Fixed<N>> {
@@ -1480,6 +1487,30 @@ mod bitlist {
         assert_eq!(e, Error::OutOfBounds { i: 9, len: 8 });
     }
 
+    #[test]
+    fn clone_zeroed() {
+        let mut bitfield = BitList1024::with_capacity(16).unwrap();
+        bitfield.set(0, true).unwrap();
+        bitfield.set(5, true).unwrap();
+        bitfield.set(15, true).unwrap();
+
+        let zeroed = bitfield.clone_zeroed();
+        assert_eq!(zeroed.len(), 16);
+        assert!(zeroed.is_zero());
+
+        let mut bitfield = BitList1::with_capacity(1).unwrap();
+        bitfield.set(0, true).unwrap();
+
+        let zeroed = bitfield.clone_zeroed();
+        assert_eq!(zeroed.len(), 1);
+        assert!(zeroed.is_zero());
+
+        let empty = BitList0::with_capacity(0).unwrap();
+        let zeroed_empty = empty.clone_zeroed();
+        assert_eq!(zeroed_empty.len(), 0);
+        assert!(zeroed_empty.is_zero());
+    }
+
     #[test]
     fn display() {
         let bitlist = BitList1024::from_raw_bytes(smallvec![0b0011_1111, 0b0001_0101], 15).unwrap();