wallet: Add a deprecation warning for newly created legacy wallets

src/wallet/rpc/wallet.cpp

@@ -315,7 +315,9 @@ static RPCHelpMan createwallet()
             {"blank", RPCArg::Type::BOOL, RPCArg::Default{false}, "Create a blank wallet. A blank wallet has no keys or HD seed. One can be set using sethdseed."},
             {"passphrase", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "Encrypt the wallet with this passphrase."},
             {"avoid_reuse", RPCArg::Type::BOOL, RPCArg::Default{false}, "Keep track of coin reuse, and treat dirty and clean coins differently with privacy considerations in mind."},
-            {"descriptors", RPCArg::Type::BOOL, RPCArg::Default{true}, "Create a native descriptor wallet. The wallet will use descriptors internally to handle address creation"},
+            {"descriptors", RPCArg::Type::BOOL, RPCArg::Default{true}, "Create a native descriptor wallet. The wallet will use descriptors internally to handle address creation."
+                                                                       " Setting to \"false\" will create a legacy wallet; however, the legacy wallet type is being deprecated and"
+                                                                       " support for creating and opening legacy wallets will be removed in the future."},
             {"load_on_startup", RPCArg::Type::BOOL, RPCArg::Optional::OMITTED_NAMED_ARG, "Save wallet name to persistent settings and load on startup. True to add wallet to startup list, false to remove, null to leave unchanged."},
             {"external_signer", RPCArg::Type::BOOL, RPCArg::Default{false}, "Use an external signer such as a hardware wallet. Requires -signer to be configured. Wallet creation will fail if keys cannot be fetched. Requires disable_private_keys and descriptors set to true."},
         },

src/wallet/wallet.cpp

@@ -354,6 +354,11 @@ std::shared_ptr<CWallet> CreateWallet(WalletContext& context, const std::string&
     // Write the wallet settings
     UpdateWalletSetting(*context.chain, name, load_on_start, warnings);
 
+    // Legacy wallets are being deprecated, warn if a newly created wallet is legacy
+    if (!(wallet_creation_flags & WALLET_FLAG_DESCRIPTORS)) {
+        warnings.push_back(_("Wallet created successfully. The legacy wallet type is being deprecated and support for creating and opening legacy wallets will be removed in the future."));
+    }
+
     status = DatabaseStatus::SUCCESS;
     return wallet;
 }

test/functional/wallet_createwallet.py

@@ -164,5 +164,10 @@ class CreateWalletTest(BitcoinTestFramework):
         self.log.info('Using a passphrase with private keys disabled returns error')
         assert_raises_rpc_error(-4, 'Passphrase provided but private keys are disabled. A passphrase is only used to encrypt private keys, so cannot be used for wallets with private keys disabled.', self.nodes[0].createwallet, wallet_name='w9', disable_private_keys=True, passphrase='thisisapassphrase')
 
+        if self.is_bdb_compiled():
+            self.log.info("Test legacy wallet deprecation")
+            res = self.nodes[0].createwallet(wallet_name="legacy_w0", descriptors=False, passphrase=None)
+            assert_equal(res["warning"], "Wallet created successfully. The legacy wallet type is being deprecated and support for creating and opening legacy wallets will be removed in the future.")
+
 if __name__ == '__main__':
     CreateWalletTest().main()