Informational 19 Bitcoin Committed Aug 4, 2026 · 11:31 UTC

Merge rust-bitcoin/rust-bitcoin#6661: units: Remove `From<u16>` from `NumberOfBlocks`

ed5f1b68 View source ↗

Public commit record

What the developer wrote

Authored by Andrew Poelstra

91/100 · Strong

Merge rust-bitcoin/rust-bitcoin#6661: units: Remove `From<u16>` from `NumberOfBlocks`

6ea25bed2982858815abeb8788f12f342584108b Update API files (Mitchell Bagot)
f9b08eb1fb1ec6871d144f16c6fdad3d13d9b552 Remove From<u16> from NumberOfBlocks (Mitchell Bagot)

Pull request description:

The NumberOfBlocks type has a From\<u16> impl on it, which is used to simplify construction of the type in various tests. However, the from_height constructor already takes a u16 and functions identically. Since the NumberOf512Seconds type has no such From impl, it should be removed from this to reduce the API surface and make the two consistent.

Remove From\<u16> impl from NumberOfBlocks.

ACKs for top commit:
apoelstra:
ACK 6ea25bed2982858815abeb8788f12f342584108b; successfully ran local tests
tcharding:
ACK 6ea25bed2982858815abeb8788f12f342584108b

Tree-SHA512: dbe29afbab5bfbbbb411fd7789ad0c5e289b2991784d130fa67a5eb1f4122c1f5da6fe09a8acb1ddb3dc4d3ffbe8845588578bcfe60df1be9f16ceaef7ae5872

✓ Specific, descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context✓ Mentions testing or verification✓ Links an issue, advisory, or supporting reference

The short version

What changed, and why it matters

This is a routine API cleanup, not a security fix. The developers removed a shortcut that let programmers create a 'number of blocks' value directly from any u16 number, replacing it with an existing named constructor called from_height. The behavior of the code is unchanged; only the way callers write it is slightly different. There is no vulnerability here.

Recommended action

No security action needed. Treat as a normal semver-aware API change; downstream code using NumberOfBlocks::from(u16) will need to switch to NumberOfBlocks::from_height.

Security signals we found

No strong security signals were identified.

Technical analysis

Evidence from the diff

The commit removes impl From for relative::NumberOfBlocks and updates all call sites to use NumberOfBlocks::from_height, which already accepted u16 and had identical semantics. The change is purely a public-API surface reduction to make NumberOfBlocks consistent with NumberOf512Seconds. No bounds checks, encoding, or locktime logic were altered. The diff is entirely mechanical substitution plus generated API file updates.

Changed components

bitcoin_units::locktime::relative::NumberOfBlocksbitcoin_units::sequence::Sequencebitcoin_units::block::BlockHeightInterval

Inspect captured patch +18 / −35

### bitcoin/tests/serde.rs
@@ -51,7 +51,7 @@ fn serde_regression_absolute_lock_time_time() {
 
 #[test]
 fn serde_regression_relative_lock_time_height() {
-    let t = relative::LockTime::from(relative::NumberOfBlocks::from(0xCAFE_u16));
+    let t = relative::LockTime::from(relative::NumberOfBlocks::from_height(0xCAFE));
 
     let got = serialize(&t).unwrap();
     let want = include_bytes!("data/serde/relative_lock_time_blocks_bincode") as &[_];

### units/api/all-features.txt
@@ -5973,8 +5973,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
@@ -8019,8 +8017,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]

### units/api/alloc-only.txt
@@ -4883,8 +4883,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
@@ -6655,8 +6653,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]

### units/api/no-features.txt
@@ -4327,8 +4327,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
@@ -5875,8 +5873,6 @@ impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for
   pub fn bitcoin_units::block::BlockHeightInterval::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::block::BlockHeightInterval]
 impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime
   pub fn bitcoin_units::locktime::relative::LockTime::from(h: bitcoin_units::locktime::relative::NumberOfBlocks) -> Self [impl: impl core::convert::From<bitcoin_units::locktime::relative::NumberOfBlocks> for bitcoin_units::locktime::relative::LockTime]
-impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks
-  pub fn bitcoin_units::locktime::relative::NumberOfBlocks::from(value: u16) -> Self [impl: impl core::convert::From<u16> for bitcoin_units::locktime::relative::NumberOfBlocks]
 impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks
   pub type bitcoin_units::locktime::relative::NumberOfBlocks::Error = bitcoin_units::parse_int::error::ParseIntError [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]
   pub fn bitcoin_units::locktime::relative::NumberOfBlocks::try_from(s: &str) -> core::result::Result<Self, Self::Error> [impl: impl core::convert::TryFrom<&str> for bitcoin_units::locktime::relative::NumberOfBlocks]

### units/src/block.rs
@@ -308,7 +308,7 @@ impl TryFrom<BlockHeightInterval> for relative::NumberOfBlocks {
     #[inline]
     fn try_from(h: BlockHeightInterval) -> Result<Self, Self::Error> {
         u16::try_from(h.to_u32())
-            .map(Self::from)
+            .map(Self::from_height)
             .map_err(|_| TooBigForRelativeHeightError(h.into()))
     }
 }
@@ -709,7 +709,7 @@ mod tests {
         assert_eq!(interval, 100);
 
         let interval_from_height: BlockHeightInterval =
-            relative::NumberOfBlocks::from(10u16).into();
+            relative::NumberOfBlocks::from_height(10).into();
         assert_eq!(interval_from_height.to_u32(), 10u32);
 
         let invalid_height_greater =

### units/src/locktime/relative/error.rs
@@ -309,7 +309,7 @@ mod tests {
         assert!(e.source().is_none());
 
         // InvalidHeightError - is_satisfied_by with invalid args
-        let blocks = NumberOfBlocks::from(10u16);
+        let blocks = NumberOfBlocks::from_height(10);
         let e = blocks
             .is_satisfied_by(BlockHeight::from_u32(5), BlockHeight::from_u32(10))
             .unwrap_err();

### units/src/locktime/relative/mod.rs
@@ -451,12 +451,7 @@ impl NumberOfBlocks {
 
 crate::internal_macros::impl_fmt_traits_for_u32_wrapper!(NumberOfBlocks);
 
-impl From<u16> for NumberOfBlocks {
-    #[inline]
-    fn from(value: u16) -> Self { Self(value) }
-}
-
-parse_int::impl_parse_str_from_int_infallible!(NumberOfBlocks, u16, from);
+parse_int::impl_parse_str_from_int_infallible!(NumberOfBlocks, u16, from_height);
 
 impl fmt::Display for NumberOfBlocks {
     #[inline]
@@ -703,8 +698,8 @@ mod tests {
 
     #[test]
     fn parses_correctly_to_height_or_time() {
-        let height1 = NumberOfBlocks::from(10);
-        let height2 = NumberOfBlocks::from(11);
+        let height1 = NumberOfBlocks::from_height(10);
+        let height2 = NumberOfBlocks::from_height(11);
         let time1 = NumberOf512Seconds::from_512_second_intervals(70);
         let time2 = NumberOf512Seconds::from_512_second_intervals(71);
 
@@ -728,12 +723,12 @@ mod tests {
 
     #[test]
     fn height_correctly_implies() {
-        let height = NumberOfBlocks::from(10);
+        let height = NumberOfBlocks::from_height(10);
         let lock_by_height = LockTime::from(height);
 
-        assert!(!lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from(9))));
-        assert!(lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from(10))));
-        assert!(lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from(11))));
+        assert!(!lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from_height(9))));
+        assert!(lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from_height(10))));
+        assert!(lock_by_height.is_implied_by(LockTime::from(NumberOfBlocks::from_height(11))));
     }
 
     #[test]
@@ -751,7 +746,7 @@ mod tests {
 
     #[test]
     fn sequence_correctly_implies() {
-        let height = NumberOfBlocks::from(10);
+        let height = NumberOfBlocks::from_height(10);
         let time = NumberOf512Seconds::from_512_second_intervals(70);
 
         let lock_by_height = LockTime::from(height);
@@ -774,7 +769,7 @@ mod tests {
     #[test]
     fn incorrect_units_do_not_imply() {
         let time = NumberOf512Seconds::from_512_second_intervals(70);
-        let height = NumberOfBlocks::from(10);
+        let height = NumberOfBlocks::from_height(10);
 
         let lock_by_time = LockTime::from(time);
         assert!(!lock_by_time.is_implied_by(LockTime::from(height)));
@@ -853,7 +848,7 @@ mod tests {
         let lock_by_height = LockTime::from_height(10); // Arbitrary value.
         let err = lock_by_height.is_satisfied_by_time(chain_tip, mined_at).unwrap_err();
 
-        let expected_height = NumberOfBlocks::from(10);
+        let expected_height = NumberOfBlocks::from_height(10);
         assert_eq!(
             err,
             IsSatisfiedByTimeError::Incompatible(IncompatibleTimeError(expected_height))
@@ -892,10 +887,10 @@ mod tests {
         let utxo_height = BlockHeight::from_u32(80);
         let utxo_mtp = BlockMtp::new(utxo_timestamps);
 
-        let lock1 = LockTime::Blocks(NumberOfBlocks::from(10));
+        let lock1 = LockTime::Blocks(NumberOfBlocks::from_height(10));
         assert!(lock1.is_satisfied_by(chain_height, chain_mtp, utxo_height, utxo_mtp).unwrap());
 
-        let lock2 = LockTime::Blocks(NumberOfBlocks::from(21));
+        let lock2 = LockTime::Blocks(NumberOfBlocks::from_height(21));
         assert!(lock2.is_satisfied_by(chain_height, chain_mtp, utxo_height, utxo_mtp).unwrap());
 
         let lock3 = LockTime::Time(NumberOf512Seconds::from_512_second_intervals(10));
@@ -1100,7 +1095,7 @@ mod tests {
         let mined_at = BlockHeight::from_u32(u32::MIN);
         let chain_tip = BlockHeight::from_u32(u32::MAX);
 
-        let block_height = NumberOfBlocks::from(10); // Arbitrary value.
+        let block_height = NumberOfBlocks::from_height(10); // Arbitrary value.
         assert!(block_height.is_satisfied_by(chain_tip, mined_at).unwrap());
     }
 }

### units/src/sequence.rs
@@ -215,7 +215,7 @@ impl Sequence {
         if self.is_time_locked() {
             Some(LockTime::from(NumberOf512Seconds::from_512_second_intervals(lock_value)))
         } else {
-            Some(LockTime::from(NumberOfBlocks::from(lock_value)))
+            Some(LockTime::from(NumberOfBlocks::from_height(lock_value)))
         }
     }

Risk score

Why this scored 19/100

Our methodology →

Potential impact 0/30

Exploitability 0/25

Stealth signal 0/15

Affected reach 5/15

Confidence 9/10

Evidence quality 5/5

Human-validated context

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The AI analysis stands alone for now. Submit a note if you can add evidence or important context.

What the developer wrote

What changed, and why it matters

Security signals we found

Evidence from the diff

Changed components

Why this scored 19/100

Community notes

Related watches

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