Informational 18 Bitcoin Committed Jul 17, 2026 · 16:52 UTC

Add `impl Clone for Box<{custom DST}>`

9b738a5f View source ↗

Public commit record

What the developer wrote

Authored by Martin Habovstiak

78/100 · Adequate

Add `impl Clone for Box<{custom DST}>`

`Script<T>` and `PushBytes` are unsized types wrapping `[u8]`. The standard
library only provides `Clone for Box<T>` where `T: Clone + Sized`, so
`Box<Script<T>>` and `Box<PushBytes>` were missing `Clone` implementations.

Add manual `impl<T> Clone for Box<Script<T>>` and `impl Clone for
Box<PushBytes>` that clone the underlying bytes and wrap them in new boxed
values via `from_boxed_bytes` / `from_boxed_slice_unchecked`.

Also add the corresponding `Box<{Script variant}>` and `Box<PushBytes>` fields
to the API test's `Clone` struct (guarded by `#[cfg(feature = "alloc")]`) so
that these impls are covered by the compile-time API surface tests.

✓ Descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context✓ Mentions testing or verification

The short version

What changed, and why it matters

This commit adds the ability to clone boxed versions of two custom unsized byte-wrapping types used in Bitcoin scripts. Before this change, code that tried to clone a Box<Script> or Box<PushBytes> would fail to compile. The change is a normal API completeness fix and does not appear to fix any memory-safety bug or security vulnerability.

Recommended action

No security action required. Treat as a routine API enhancement. Reviewers may verify that the unchecked constructors preserve invariants (length < 2^32), which the commit message and code comment assert is maintained by cloning from a valid value.

Security signals we found

No security-relevant keywords in commit title or message

No unsafe code introduced in the diff

No bounds-checking or validation logic changed

No incident, CVE, or disclosure references present

Change is purely additive API surface expansion

Technical analysis

Evidence from the diff

The patch manually implements Clone for Box> and Box because Rust’s standard library only provides Clone for Box where T: Sized. The implementations copy the underlying byte slice into a new boxed value using existing unchecked constructors (from_boxed_bytes / from_boxed_slice_unchecked). The commit also updates API-surface test files to record the new impls and adds compile-time test coverage. There is no evidence of a vulnerability being patched; it is a missing-trait-impl feature addition.

Changed components

primitives/src/script/borrowed.rsprimitives/src/script/push_bytes.rsprimitives/api/all-features.txtprimitives/api/alloc-only.txtprimitives/tests/api.rs

Inspect captured patch +50 / −1

diff --git a/primitives/api/all-features.txt b/primitives/api/all-features.txt
index c6fcde22..b50f10a8 100644
--- a/primitives/api/all-features.txt
+++ b/primitives/api/all-features.txt
@@ -2306,6 +2306,8 @@ impl core::borrow::Borrow<bitcoin_primitives::script::PushBytes> for bitcoin_pri
   pub fn bitcoin_primitives::script::PushBytesBuf::borrow(&self) -> &bitcoin_primitives::script::PushBytes [impl: impl core::borrow::Borrow<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf]
 impl core::borrow::BorrowMut<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf
   pub fn bitcoin_primitives::script::PushBytesBuf::borrow_mut(&mut self) -> &mut bitcoin_primitives::script::PushBytes [impl: impl core::borrow::BorrowMut<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf]
+impl core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::PushBytes>
+  pub fn alloc::boxed::Box<bitcoin_primitives::script::PushBytes>::clone(&self) -> Self [impl: impl core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::PushBytes>]
 impl core::cmp::Eq for bitcoin_primitives::script::PushBytes
 impl core::cmp::Ord for bitcoin_primitives::script::PushBytes
   pub fn bitcoin_primitives::script::PushBytes::cmp(&self, other: &bitcoin_primitives::script::PushBytes) -> core::cmp::Ordering [impl: impl core::cmp::Ord for bitcoin_primitives::script::PushBytes]
@@ -3602,6 +3604,8 @@ impl<T> core::borrow::Borrow<bitcoin_primitives::script::Script<T>> for bitcoin_
   pub fn bitcoin_primitives::script::ScriptBuf<T>::borrow(&self) -> &bitcoin_primitives::script::Script<T> [impl: impl<T> core::borrow::Borrow<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>]
 impl<T> core::borrow::BorrowMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>
   pub fn bitcoin_primitives::script::ScriptBuf<T>::borrow_mut(&mut self) -> &mut bitcoin_primitives::script::Script<T> [impl: impl<T> core::borrow::BorrowMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>]
+impl<T> core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::Script<T>>
+  pub fn alloc::boxed::Box<bitcoin_primitives::script::Script<T>>::clone(&self) -> Self [impl: impl<T> core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::Script<T>>]
 impl<T> core::convert::AsMut<[u8]> for bitcoin_primitives::script::Script<T>
   pub fn bitcoin_primitives::script::Script<T>::as_mut(&mut self) -> &mut [u8] [impl: impl<T> core::convert::AsMut<[u8]> for bitcoin_primitives::script::Script<T>]
 impl<T> core::convert::AsMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::Script<T>
diff --git a/primitives/api/alloc-only.txt b/primitives/api/alloc-only.txt
index fed9ec35..d2b1eda1 100644
--- a/primitives/api/alloc-only.txt
+++ b/primitives/api/alloc-only.txt
@@ -2168,6 +2168,8 @@ impl core::borrow::Borrow<bitcoin_primitives::script::PushBytes> for bitcoin_pri
   pub fn bitcoin_primitives::script::PushBytesBuf::borrow(&self) -> &bitcoin_primitives::script::PushBytes [impl: impl core::borrow::Borrow<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf]
 impl core::borrow::BorrowMut<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf
   pub fn bitcoin_primitives::script::PushBytesBuf::borrow_mut(&mut self) -> &mut bitcoin_primitives::script::PushBytes [impl: impl core::borrow::BorrowMut<bitcoin_primitives::script::PushBytes> for bitcoin_primitives::script::PushBytesBuf]
+impl core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::PushBytes>
+  pub fn alloc::boxed::Box<bitcoin_primitives::script::PushBytes>::clone(&self) -> Self [impl: impl core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::PushBytes>]
 impl core::cmp::Eq for bitcoin_primitives::script::PushBytes
 impl core::cmp::Ord for bitcoin_primitives::script::PushBytes
   pub fn bitcoin_primitives::script::PushBytes::cmp(&self, other: &bitcoin_primitives::script::PushBytes) -> core::cmp::Ordering [impl: impl core::cmp::Ord for bitcoin_primitives::script::PushBytes]
@@ -3453,6 +3455,8 @@ impl<T> core::borrow::Borrow<bitcoin_primitives::script::Script<T>> for bitcoin_
   pub fn bitcoin_primitives::script::ScriptBuf<T>::borrow(&self) -> &bitcoin_primitives::script::Script<T> [impl: impl<T> core::borrow::Borrow<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>]
 impl<T> core::borrow::BorrowMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>
   pub fn bitcoin_primitives::script::ScriptBuf<T>::borrow_mut(&mut self) -> &mut bitcoin_primitives::script::Script<T> [impl: impl<T> core::borrow::BorrowMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::ScriptBuf<T>]
+impl<T> core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::Script<T>>
+  pub fn alloc::boxed::Box<bitcoin_primitives::script::Script<T>>::clone(&self) -> Self [impl: impl<T> core::clone::Clone for alloc::boxed::Box<bitcoin_primitives::script::Script<T>>]
 impl<T> core::convert::AsMut<[u8]> for bitcoin_primitives::script::Script<T>
   pub fn bitcoin_primitives::script::Script<T>::as_mut(&mut self) -> &mut [u8] [impl: impl<T> core::convert::AsMut<[u8]> for bitcoin_primitives::script::Script<T>]
 impl<T> core::convert::AsMut<bitcoin_primitives::script::Script<T>> for bitcoin_primitives::script::Script<T>
diff --git a/primitives/src/script/borrowed.rs b/primitives/src/script/borrowed.rs
index 99b5de2f..d0590a00 100644
--- a/primitives/src/script/borrowed.rs
+++ b/primitives/src/script/borrowed.rs
@@ -105,6 +105,14 @@ impl<T> ToOwned for Script<T> {
     fn to_owned(&self) -> Self::Owned { ScriptBuf::from_bytes(self.to_vec()) }
 }
 
+#[cfg(feature = "alloc")]
+impl<T> Clone for Box<Script<T>> {
+    #[inline]
+    fn clone(&self) -> Self {
+        Script::from_boxed_bytes(self.as_bytes().to_owned().into_boxed_slice())
+    }
+}
+
 impl<T> Script<T> {
     /// Constructs a new empty script.
     #[inline]
diff --git a/primitives/src/script/push_bytes.rs b/primitives/src/script/push_bytes.rs
index 48dc940e..7b9cd176 100644
--- a/primitives/src/script/push_bytes.rs
+++ b/primitives/src/script/push_bytes.rs
@@ -6,6 +6,11 @@ use core::borrow::{Borrow, BorrowMut};
 use core::convert::Infallible;
 use core::ops::{Deref, DerefMut};
 
+#[cfg(feature = "alloc")]
+use alloc::borrow::ToOwned as _;
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
+
 #[rustfmt::skip]                // Keep public re-exports separate.
 #[doc(inline)]
 // This is not the usual re-export, `primitive` here is a code audit thing.
@@ -55,6 +60,11 @@ mod primitive {
             ///
             /// The caller is responsible for checking that the length is less than the 2^32.
             fn from_mut_slice_unchecked(bytes: &mut _) -> &mut Self;
+
+            /// Converts a `Box<[u8]>` into a `Box<PushBytes>` without checking the length.
+            ///
+            /// The caller is responsible for checking that the length is less than 2^32.
+            pub(super) fn from_boxed_slice_unchecked(bytes: Box<_>) -> Box<Self>;
         }
     }
 
@@ -285,6 +295,15 @@ mod primitive {
     }
 }
 
+#[cfg(feature = "alloc")]
+impl Clone for Box<PushBytes> {
+    #[inline]
+    fn clone(&self) -> Self {
+        // The invariant (length < 2^32) is maintained because we clone from a valid `PushBytes`.
+        PushBytes::from_boxed_slice_unchecked(self.as_bytes().to_owned().into_boxed_slice())
+    }
+}
+
 impl PushBytes {
     /// Returns the number of bytes in buffer.
     pub fn len(&self) -> usize { self.as_bytes().len() }
diff --git a/primitives/tests/api.rs b/primitives/tests/api.rs
index c99d975a..510838ea 100644
--- a/primitives/tests/api.rs
+++ b/primitives/tests/api.rs
@@ -13,10 +13,12 @@
 #![cfg(feature = "hex")]
 #![cfg(feature = "arbitrary")]
 
+extern crate alloc;
+
 use arbitrary::Arbitrary;
 use bitcoin_primitives::block::{Checked, Unchecked};
 use bitcoin_primitives::script::{
-    self, ScriptHash, ScriptPubKeyBufDecoder, ScriptSigBufDecoder, WScriptHash,
+    self, PushBytes, ScriptHash, ScriptPubKeyBufDecoder, ScriptSigBufDecoder, WScriptHash,
 };
 use bitcoin_primitives::{
     absolute, block, merkle_tree, pow, relative, transaction, witness, OutPoint, RedeemScript,
@@ -125,6 +127,18 @@ struct Clone<'a> {
     h: merkle_tree::WitnessMerkleNode,
     i: pow::CompactTarget,
     // j: &'a Script,
+    #[cfg(feature = "alloc")]
+    j0: alloc::boxed::Box<PushBytes>,
+    #[cfg(feature = "alloc")]
+    j1: alloc::boxed::Box<RedeemScript>,
+    #[cfg(feature = "alloc")]
+    j2: alloc::boxed::Box<ScriptPubKey>,
+    #[cfg(feature = "alloc")]
+    j3: alloc::boxed::Box<ScriptSig>,
+    #[cfg(feature = "alloc")]
+    j4: alloc::boxed::Box<TapScript>,
+    #[cfg(feature = "alloc")]
+    j5: alloc::boxed::Box<WitnessScript>,
     k: ScriptHash,
     l: WScriptHash,
     m1: RedeemScriptBuf,

Risk score

Why this scored 18/100

Our methodology →

Potential impact 0/30

Exploitability 0/25

Stealth signal 0/15

Affected reach 5/15

Confidence 9/10

Evidence quality 4/5

Human-validated context

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What the developer wrote

What changed, and why it matters

Security signals we found

Evidence from the diff

Changed components

Why this scored 18/100

Community notes

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Update API files

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