From 83abd5b89ae0138a777fe634b54e39325632447d Mon Sep 17 00:00:00 2001
From: Riccardo Casatta <riccardo@casatta.it>
Date: Tue, 14 Jan 2025 10:03:51 +0100
Subject: [PATCH] maintain provably unspendable semantincs

---
 src/rest.rs             |  4 ++--
 src/util/mod.rs         |  1 +
 src/util/script.rs      | 15 +++++++++++++++
 src/util/transaction.rs |  2 +-
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/rest.rs b/src/rest.rs
index ca94afa68..91afcbf3a 100644
--- a/src/rest.rs
+++ b/src/rest.rs
@@ -305,7 +305,7 @@ impl TxOutValue {
             "fee"
         } else if script.is_empty() {
             "empty"
-        } else if script.is_op_return() {
+        } else if crate::util::provably_unspendable(&script) {
             "op_return"
         } else if script.is_p2pk() {
             "p2pk"
@@ -319,7 +319,7 @@ impl TxOutValue {
             "v0_p2wsh"
         } else if script.is_p2tr() {
             "v1_p2tr"
-        } else if script.is_op_return() {
+        } else if crate::util::provably_unspendable(&script) {
             "provably_unspendable"
         } else {
             "unknown"
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 0a9701b8e..18b0c5c92 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -10,6 +10,7 @@ pub use self::block::{
     BlockHeaderMeta, BlockId, BlockMeta, BlockStatus, HeaderEntry, HeaderList, DEFAULT_BLOCKHASH,
 };
 pub use self::fees::get_tx_fee;
+pub(crate) use self::script::provably_unspendable;
 pub use self::script::{get_innerscripts, ScriptToAddr, ScriptToAsm};
 pub use self::transaction::{
     extract_tx_prevouts, get_prev_outpoints, has_prevout, is_coinbase, is_spendable,
diff --git a/src/util/script.rs b/src/util/script.rs
index 9f44c4ea6..d04c5f87d 100644
--- a/src/util/script.rs
+++ b/src/util/script.rs
@@ -79,3 +79,18 @@ pub fn get_innerscripts(txin: &TxIn, prevout: &TxOut) -> InnerScripts {
         witness_script,
     }
 }
+
+/// Compatible with Script::is_provably_unspendable on rust-bitcoin v0.31 and before because it checks also IllegalOp class
+pub(crate) fn provably_unspendable(script: &Script) -> bool {
+    use bitcoin::blockdata::opcodes::Class::{IllegalOp, ReturnOp};
+
+    match script.as_bytes().first() {
+        Some(b) => {
+            let first = bitcoin::Opcode::from(*b);
+            let class = first.classify(bitcoin::blockdata::opcodes::ClassifyContext::Legacy);
+
+            class == ReturnOp || class == IllegalOp
+        }
+        None => false,
+    }
+}
diff --git a/src/util/transaction.rs b/src/util/transaction.rs
index af3d87c98..6775ca754 100644
--- a/src/util/transaction.rs
+++ b/src/util/transaction.rs
@@ -70,7 +70,7 @@ pub fn has_prevout(txin: &TxIn) -> bool {
 
 pub fn is_spendable(txout: &TxOut) -> bool {
     #[cfg(not(feature = "liquid"))]
-    return !txout.script_pubkey.is_op_return();
+    return !crate::util::provably_unspendable(&txout.script_pubkey);
     #[cfg(feature = "liquid")]
     return !txout.is_fee() && !txout.script_pubkey.is_provably_unspendable();
 }