Merge rust-bitcoin#5095: chore: clarify last_pushdata comment

894a255 docs: clarify last pushdata comment (Galoretka)

Pull request description:

  The inline comment in last_pushdata was misleading and outdated. It claimed to “handle op codes up to (but excluding) OP_PUSHNUM_NEG”, implying special treatment for numeric push opcodes and referencing a deprecated name. In reality, last_pushdata only returns true data pushes (Instruction::PushBytes) and excludes numeric push opcodes (OP_0, OP_1NEGATE, OP_1..OP_16) since they are emitted as Instruction::Op. Updated the comment to explicitly state this behavior. No logic changes.


ACKs for top commit:
  apoelstra:
    ACK 894a255; successfully ran local tests
  tcharding:
    ACK 894a255


Tree-SHA512: b295ee2ff87a55e9040ce96bf1e1681ba20c0f2946853cdb8e70c35daf7acbeb377f6d563d63e6beaab56081f265a56b2c2e9b72c82d45d9d0ff6d9185fe4b85

Author: apoelstra

bitcoin/src/blockdata/script/borrowed.rs

@@ -529,7 +529,10 @@ internal_macros::define_extension_trait! {
         /// Returns `None` if the instruction is an opcode or if the script is empty.
         fn last_pushdata(&self) -> Option<&PushBytes> {
             match self.instructions().last() {
-                // Handles op codes up to (but excluding) OP_PUSHNUM_NEG.
+                // Returns only true data pushes.
+                // Note: OP_0 (empty push) is included as PushBytes; numeric push opcodes
+                // OP_1NEGATE and OP_1..OP_16 are opcodes (not pushdata) and thus excluded.
+                // OP_RESERVED is also excluded.
                 Some(Ok(Instruction::PushBytes(bytes))) => Some(bytes),
                 // OP_16 (0x60) and lower are considered "pushes" by Bitcoin Core (excl. OP_RESERVED).
                 // However we are only interested in the pushdata so we can ignore them.