Merge #16144: wallet: do not encrypt wallets with disabled private keys

7860c98 wallet: do not encrypt wallets with disabled private keys (whythat)

Pull request description:

  Fix for #15635.
  Throw an `RPC_WALLET_ENCRYPTION_FAILED` error when attempting to encrypt wallet with disabled private keys. Changed `test/function/wallet_createwallet.py` to test new behavior.

ACKs for commit 7860c9:
  achow101:
    utACK 7860c98
  meshcollider:
    utACK bitcoin/bitcoin@7860c98

Tree-SHA512: d0cc40efd303a00d0b4d3cb2de59d8d2d7dd35647e7f3fe9d4a8986589499c1f567c5780c83a129e1ab8dbe601279c459c6ebce3b48b1d81d47a28616ef4a369

Author: laanwj

src/wallet/rpcwallet.cpp

@@ -2124,6 +2124,10 @@ static UniValue encryptwallet(const JSONRPCRequest& request)
     auto locked_chain = pwallet->chain().lock();
     LOCK(pwallet->cs_wallet);
 
+    if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
+        throw JSONRPCError(RPC_WALLET_ENCRYPTION_FAILED, "Error: wallet does not contain private keys, nothing to encrypt.");
+    }
+
     if (pwallet->IsCrypted()) {
         throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an encrypted wallet, but encryptwallet was called.");
     }

test/functional/wallet_createwallet.py

@@ -92,7 +92,7 @@ def run_test(self):
         assert_raises_rpc_error(-4, "Error: This wallet has no available keys", w5.getnewaddress)
         assert_raises_rpc_error(-4, "Error: This wallet has no available keys", w5.getrawchangeaddress)
         # Encrypt the wallet
-        w5.encryptwallet('pass')
+        assert_raises_rpc_error(-16, "Error: wallet does not contain private keys, nothing to encrypt.", w5.encryptwallet, 'pass')
         assert_raises_rpc_error(-4, "Error: This wallet has no available keys", w5.getnewaddress)
         assert_raises_rpc_error(-4, "Error: This wallet has no available keys", w5.getrawchangeaddress)