Clean up help messages for RPC createrawtransaction.

Also return error if expiryheight used when Overwinter not active.

src/rpc/rawtransaction.cpp

@@ -412,7 +412,7 @@ UniValue createrawtransaction(const UniValue& params, bool fHelp)
 {
     if (fHelp || params.size() < 2 || params.size() > 4)
         throw runtime_error(
-            "createrawtransaction [{\"txid\":\"id\",\"vout\":n},...] {\"address\":amount,...} ( locktime )\n"
+            "createrawtransaction [{\"txid\":\"id\",\"vout\":n},...] {\"address\":amount,...} ( locktime ) ( expiryheight )\n"
             "\nCreate a transaction spending the given inputs and sending to the given addresses.\n"
             "Returns hex-encoded raw transaction.\n"
             "Note that the transaction's inputs are not signed, and\n"
@@ -422,7 +422,7 @@ UniValue createrawtransaction(const UniValue& params, bool fHelp)
             "1. \"transactions\"        (string, required) A json array of json objects\n"
             "     [\n"
             "       {\n"
-            "         \"txid\":\"id\",  (string, required) The transaction id\n"
+            "         \"txid\":\"id\",    (string, required) The transaction id\n"
             "         \"vout\":n        (numeric, required) The output number\n"
             "         \"sequence\":n    (numeric, optional) The sequence number\n"
             "       }\n"
@@ -433,8 +433,8 @@ UniValue createrawtransaction(const UniValue& params, bool fHelp)
             "      \"address\": x.xxx   (numeric, required) The key is the Zcash address, the value is the " + CURRENCY_UNIT + " amount\n"
             "      ,...\n"
             "    }\n"
-            "3. locktime                (numeric, optional, default=0) Raw locktime. Non-0 value also locktime-activates inputs\n"
-            "4. expiryheight            (numeric, optional, default=0) Expiry height of transaction\n"
+            "3. locktime              (numeric, optional, default=0) Raw locktime. Non-0 value also locktime-activates inputs\n"
+            "4. expiryheight          (numeric, optional, default=" + strprintf("%d", DEFAULT_TX_EXPIRY_DELTA) + ") Expiry height of transaction (if Overwinter is active)\n"
             "\nResult:\n"
             "\"transaction\"            (string) hex string of the transaction\n"
 
@@ -462,13 +462,15 @@ UniValue createrawtransaction(const UniValue& params, bool fHelp)
         rawTx.nLockTime = nLockTime;
     }
     
-    if (NetworkUpgradeActive(nextBlockHeight, Params().GetConsensus(), Consensus::UPGRADE_OVERWINTER)) {
-        if (params.size() > 3 && !params[3].isNull()) {
+    if (params.size() > 3 && !params[3].isNull()) {
+        if (NetworkUpgradeActive(nextBlockHeight, Params().GetConsensus(), Consensus::UPGRADE_OVERWINTER)) {
             int64_t nExpiryHeight = params[3].get_int64();
             if (nExpiryHeight < 0 || nExpiryHeight >= TX_EXPIRY_HEIGHT_THRESHOLD) {
-                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, nExpiryHeight must be less than TX_EXPIRY_HEIGHT_THRESHOLD.");
+                throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, expiryheight must be nonnegative and less than %d.", TX_EXPIRY_HEIGHT_THRESHOLD));
             }
             rawTx.nExpiryHeight = nExpiryHeight;
+        } else {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, expiryheight can only be used if Overwinter is active when the transaction is mined");
         }
     }