Check wallet latest anchor against hashFinalOrchardRoot in ChainTip.

This will cause test failures until note commitment tree persistence
is implemented.

src/rust/include/rust/orchard/wallet.h

@@ -95,6 +95,13 @@ bool orchard_wallet_append_bundle_commitments(
         const OrchardBundlePtr* bundle
         );
 
+/**
+ * Returns the root of the wallet's note commitment tree.
+ */
+void orchard_wallet_commitment_tree_root(
+        const OrchardWalletPtr* wallet,
+        unsigned char* root_ret);
+
 /**
  * Returns whether the specified transaction contains any Orchard notes that belong
  * to this wallet.

src/rust/src/wallet.rs

@@ -472,6 +472,10 @@ impl Wallet {
             })
             .collect()
     }
+
+    pub fn note_commitment_tree_root(&self) -> MerkleHashOrchard {
+        self.witness_tree.root()
+    }
 }
 
 #[no_mangle]
@@ -507,18 +511,23 @@ pub extern "C" fn orchard_wallet_is_checkpointed(wallet: *const Wallet) -> bool
 
 #[no_mangle]
 pub extern "C" fn orchard_wallet_rewind(
-    wallet: *mut Wallet, 
+    wallet: *mut Wallet,
     to_height: BlockHeight,
-    blocks_rewound: *mut u32) -> bool {
+    blocks_rewound: *mut u32,
+) -> bool {
     let wallet = unsafe { wallet.as_mut() }.expect("Wallet pointer may not be null");
-    let blocks_rewound = unsafe { blocks_rewound.as_mut() }.expect("Return value pointer may not be null.");
+    let blocks_rewound =
+        unsafe { blocks_rewound.as_mut() }.expect("Return value pointer may not be null.");
     match wallet.rewind(to_height) {
         Ok(rewound) => {
             *blocks_rewound = rewound;
             true
         }
         Err(e) => {
-            error!("Unable to rewind the wallet to height {:?}: {:?}", to_height, e);
+            error!(
+                "Unable to rewind the wallet to height {:?}: {:?}",
+                to_height, e
+            );
             false
         }
     }
@@ -559,6 +568,17 @@ pub extern "C" fn orchard_wallet_append_bundle_commitments(
     true
 }
 
+#[no_mangle]
+pub extern "C" fn orchard_wallet_commitment_tree_root(
+    wallet: *const Wallet,
+    root_ret: *mut [u8; 32],
+) {
+    let wallet = unsafe { wallet.as_ref() }.expect("Wallet pointer may not be null");
+    let root_ret = unsafe { root_ret.as_mut() }.expect("Cannot return to the null pointer.");
+
+    *root_ret = wallet.note_commitment_tree_root().to_bytes();
+}
+
 #[no_mangle]
 pub extern "C" fn orchard_wallet_add_spending_key(wallet: *mut Wallet, sk: *const SpendingKey) {
     let wallet = unsafe { wallet.as_mut() }.expect("Wallet pointer may not be null");

src/wallet/orchard.h

@@ -135,6 +135,12 @@ public:
         return true;
     }
 
+    uint256 GetLatestAnchor() const {
+        uint256 value;
+        orchard_wallet_commitment_tree_root(inner.get(), value.begin());
+        return value;
+    }
+
     bool TxContainsMyNotes(const uint256& txid) {
         return orchard_wallet_tx_contains_my_notes(
                 inner.get(),

src/wallet/wallet.cpp

@@ -2320,6 +2320,7 @@ void CWallet::IncrementNoteWitnesses(
     // If we're at or beyond NU5 activation, update the Orchard note commitment tree.
     if (performOrchardWalletUpdates && consensus.NetworkUpgradeActive(pindex->nHeight, Consensus::UPGRADE_NU5)) {
         assert(orchardWallet.AppendNoteCommitments(pindex->nHeight, *pblock));
+        assert(pindex->hashFinalOrchardRoot == orchardWallet.GetLatestAnchor());
     }
 
     // Update witness heights
@@ -2391,6 +2392,9 @@ void CWallet::DecrementNoteWitnesses(const Consensus::Params& consensus, const C
         uint32_t blocksRewound{0};
         assert(orchardWallet.Rewind(pindex->nHeight - 1, blocksRewound));
         assert(blocksRewound == 1);
+        if (consensus.NetworkUpgradeActive(pindex->nHeight - 1, Consensus::UPGRADE_NU5)) {
+            assert(pindex->pprev->hashFinalOrchardRoot == orchardWallet.GetLatestAnchor());
+        }
     }
 
     // For performance reasons, we write out the witness cache in