Merge #14468: [wallet] Deprecate generate RPC method

ab9aca2bdf [rpc] add 'getnewaddress' hint to 'generatetoaddress' help text. (John Newbery)
c9f02955b2 [wallet] Deprecate the generate RPC method (John Newbery)
aab81720de [tests] Add generate method to TestNode (John Newbery)
c269209336 [tests] Small fixups before deprecating generate (John Newbery)

Pull request description:

  Deprecates the `generate` RPC method.

  For concept discussion, see #14299.

  Fixes #14299.

Tree-SHA512: 16a3b8b742932e4f0476c06b23de07a34d9d215b41d9272c1c9d1e39966b0c2406f17c5ab3cc568947620c08171ebe5eb74fd7ed4b62151363e305ee2937cc80

src/rpc/mining.cpp

@@ -167,6 +167,8 @@ static UniValue generatetoaddress(const JSONRPCRequest& request)
             "\nExamples:\n"
             "\nGenerate 11 blocks to myaddress\n"
             + HelpExampleCli("generatetoaddress", "11 \"myaddress\"")
+            + "If you are running the bitcoin core wallet, you can get a new address to send the newly generated bitcoin to with:\n"
+            + HelpExampleCli("getnewaddress", "")
         );
 
     int nGenerate = request.params[0].get_int();

src/wallet/rpcwallet.cpp

@@ -3321,6 +3321,12 @@ UniValue generate(const JSONRPCRequest& request)
         );
     }
 
+    if (!IsDeprecatedRPCEnabled("generate")) {
+        throw JSONRPCError(RPC_METHOD_DEPRECATED, "The wallet generate rpc method is deprecated and will be fully removed in v0.19. "
+            "To use generate in v0.18, restart bitcoind with -deprecatedrpc=generate.\n"
+            "Clients should transition to using the node rpc method generatetoaddress\n");
+    }
+
     int num_generate = request.params[0].get_int();
     uint64_t max_tries = 1000000;
     if (!request.params[1].isNull()) {