Rename ntxid to compute_ntxid

Computing the ntxid is computationally expensive, so rename the method
accordingly.

bitcoin/src/blockdata/transaction.rs

@@ -679,11 +679,21 @@ impl Transaction {
     /// Maximum transaction weight for Bitcoin Core 25.0.
     pub const MAX_STANDARD_WEIGHT: Weight = Weight::from_wu(400_000);
 
+    /// Computes a "normalized TXID" which does not include any signatures.
+    ///
+    /// This method is deprecated.  Use `compute_ntxid` instead.
+    #[deprecated(
+        since = "0.31.0",
+        note = "ntxid has been renamed to compute_ntxid to note that it's computationally expensive.  use compute_ntxid() instead."
+    )]
+    pub fn ntxid(&self) -> sha256d::Hash { self.compute_ntxid() }
+
     /// Computes a "normalized TXID" which does not include any signatures.
     ///
     /// This gives a way to identify a transaction that is "the same" as
     /// another in the sense of having same inputs and outputs.
-    pub fn ntxid(&self) -> sha256d::Hash {
+    #[doc(alias = "ntxid")]
+    pub fn compute_ntxid(&self) -> sha256d::Hash {
         let cloned_tx = Transaction {
             version: self.version,
             lock_time: self.lock_time,
@@ -1878,17 +1888,17 @@ mod tests {
         let tx_bytes = hex!("0100000001a15d57094aa7a21a28cb20b59aab8fc7d1149a3bdbcddba9c622e4f5f6a99ece010000006c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52ffffffff0100e1f505000000001976a9140389035a9225b3839e2bbf32d826a1e222031fd888ac00000000");
         let mut tx: Transaction = deserialize(&tx_bytes).unwrap();
 
-        let old_ntxid = tx.ntxid();
+        let old_ntxid = tx.compute_ntxid();
         assert_eq!(
             format!("{:x}", old_ntxid),
             "c3573dbea28ce24425c59a189391937e00d255150fa973d59d61caf3a06b601d"
         );
         // changing sigs does not affect it
         tx.input[0].script_sig = ScriptBuf::new();
-        assert_eq!(old_ntxid, tx.ntxid());
+        assert_eq!(old_ntxid, tx.compute_ntxid());
         // changing pks does
         tx.output[0].script_pubkey = ScriptBuf::new();
-        assert!(old_ntxid != tx.ntxid());
+        assert!(old_ntxid != tx.compute_ntxid());
     }
 
     #[test]