Change default anchor depth from 10 confirmations to 3

doc/release-notes.md

@@ -11,23 +11,20 @@ Option handling
   (provided that the wallet is enabled and pruning is disabled, and unless
   `-rescan=0` is specified explicitly).
 - A new `-anchorconfirmations` argument has been added to allow the user
-  to specify the number of blocks back from the chain tip that anchors 
-  will be selected from when spending notes. By default, anchors will
-  now be selected to have 10 confirmations. Values
-  greater than 100 are not supported.
+  to specify the number of blocks back from the chain tip that anchors will be
+  selected from when spending notes. By default, anchors will now be selected
+  to have 3 confirmations. Values greater than 100 are not supported.
 
 RPC Interface
 -------------
 
 - The default `minconf` value for `z_sendmany` is now 10 confirmations instead
-  of 1. This default corresponds to the number of anchor confirmations
-  required, which may be configured with the `-anchorconfirmations` argument
-  when starting the node. If `minconf` is explicitly supplied, it will override
-  the default value provided by `-anchorconfirmations` if `minconf` specifies
-  a smaller value than the default (it is not possible to spend notes that
-  are more recent than the anchor). Selecting `minconf` values less than the default
-  is not recommended, as it allows the transaction to be distinguished from transactions 
-  using the default for `-anchorconfirmations`.
+  of 1. If `minconf` and specifies a value less than that provided for
+  `-anchorconfirmations`, it will also override that value as it is not
+  possible to spend notes that are more recent than the anchor. Selecting
+  `minconf` values less than 3 is not recommended, as it allows the transaction
+  to be distinguished from transactions using the default for
+  `-anchorconfirmations`.
 
 Build system
 ------------

src/rust/src/wallet.rs

@@ -688,6 +688,8 @@ impl Wallet {
             .collect()
     }
 
+    /// Returns the note of the Orchard note commitment tree, as of the specified checkpoint
+    /// depth. A depth of 0 corresponds to the chain tip.
     pub fn note_commitment_tree_root(&self, checkpoint_depth: usize) -> Option<MerkleHashOrchard> {
         self.witness_tree.root(checkpoint_depth)
     }

src/wallet/gtest/test_wallet.cpp

@@ -1397,19 +1397,29 @@ TEST(WalletTests, CachedWitnessesEmptyChain) {
     const auto& params = Params().GetConsensus();
     wallet.IncrementNoteWitnesses(params, &index, &block, frontiers, true);
 
+    // this death will occur because there will not be sufficient Sprout witnesses to reach the
+    // default anchor depth
     EXPECT_DEATH(::GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, nAnchorConfirmations, sproutWitnesses, saplingWitnesses),
                  "GetSproutNoteWitnesses");
 
-    for (int i = 1; i <= 8; i++) {
+    // add another block; we still don't have enough witnesses
+    {
         CBlock another_block;
         CBlockIndex another_index(another_block);
-        another_index.nHeight = i;
+        another_index.nHeight = 1;
         wallet.IncrementNoteWitnesses(params, &another_index, &another_block, frontiers, true);
     }
 
     EXPECT_DEATH(::GetWitnessesAndAnchors(wallet, sproutNotes, saplingNotes, nAnchorConfirmations, sproutWitnesses, saplingWitnesses),
                  "GetSproutNoteWitnesses");
 
+    for (int i = 2; i <= 8; i++) {
+        CBlock another_block;
+        CBlockIndex another_index(another_block);
+        another_index.nHeight = i;
+        wallet.IncrementNoteWitnesses(params, &another_index, &another_block, frontiers, true);
+    }
+
     CBlock last_block;
     CBlockIndex last_index(last_block);
     last_index.nHeight = 9;

src/wallet/rpcwallet.cpp

@@ -4878,7 +4878,7 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
             "      \"amount\":amount    (numeric, required) The numeric amount in " + CURRENCY_UNIT + " is the value\n"
             "      \"memo\":memo        (string, optional) If the address is a zaddr, raw data represented in hexadecimal string format\n"
             "    }, ... ]\n"
-            "3. minconf               (numeric, optional, default=" + strprintf("%u", nAnchorConfirmations) + ") Only use funds confirmed at least this many times.\n"
+            "3. minconf               (numeric, optional, default=" + strprintf("%u", DEFAULT_NOTE_CONFIRMATIONS) + ") Only use funds confirmed at least this many times.\n"
             "4. fee                   (numeric, optional, default=" + strprintf("%s", FormatMoney(DEFAULT_FEE)) + ") The fee amount to attach to this transaction.\n"
             "5. privacyPolicy         (string, optional, default=\"LegacyCompat\") Policy for what information leakage is acceptable.\n"
             "                         One of the following strings:\n"
@@ -5090,7 +5090,7 @@ UniValue z_sendmany(const UniValue& params, bool fHelp)
     }
 
     // Minimum confirmations
-    int nMinDepth = nAnchorConfirmations;
+    int nMinDepth = DEFAULT_NOTE_CONFIRMATIONS;
     if (params.size() > 2) {
         nMinDepth = params[2].get_int();
     }
@@ -5829,7 +5829,7 @@ UniValue z_mergetoaddress(const UniValue& params, bool fHelp)
             useAnySprout || useAnySapling ?
                 std::nullopt :
                 std::optional(NoteFilter::ForPaymentAddresses(zaddrs));
-        pwalletMain->GetFilteredNotes(sproutEntries, saplingEntries, orchardEntries, noteFilter, nAnchorConfirmations);
+        pwalletMain->GetFilteredNotes(sproutEntries, saplingEntries, orchardEntries, noteFilter, DEFAULT_NOTE_CONFIRMATIONS);
 
         // If Sapling is not active, do not allow sending from a sapling addresses.
         if (!saplingActive && saplingEntries.size() > 0) {

src/wallet/wallet.h

@@ -79,7 +79,9 @@ static const unsigned int WITNESS_CACHE_SIZE = MAX_REORG_LENGTH + 1;
 //! Amount of entropy used in generation of the mnemonic seed, in bytes.
 static const size_t WALLET_MNEMONIC_ENTROPY_LENGTH = 32;
 //! -anchorconfirmations default
-static const unsigned int DEFAULT_ANCHOR_CONFIRMATIONS = 10;
+static const unsigned int DEFAULT_ANCHOR_CONFIRMATIONS = 3;
+// Default minimum number of confirmations for note selection
+static const unsigned int DEFAULT_NOTE_CONFIRMATIONS = 10;
 
 extern const char * DEFAULT_WALLET_DAT;