Get rid of ambiguous OutputType::NONE value

Based on suggestion by Pieter Wuille <pieter.wuille@gmail.com> at
https://github.com/bitcoin/bitcoin/pull/12119#issuecomment-357982763

After #12119, the NONE output type was overloaded to refer to either an output
type that couldn't be parsed, or to an automatic change output mode.  This
change drops the NONE enum and uses a simple bool indicate parse failure, and a
new CHANGE_AUTO enum to refer the change output type.

This change is almost a pure refactoring except it makes RPCs reject empty
string ("") address types instead of treating them like they were unset. This
simplifies the parsing code a little bit and could prevent RPC usage mistakes.
It's noted in the release notes.

1 files changed, 6 insertions, 9 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index c34b166a41..f669921750 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -164,8 +164,7 @@ UniValue getnewaddress(const JSONRPCRequest& request)
 
     OutputType output_type = pwallet->m_default_address_type;
     if (!request.params[1].isNull()) {
-        output_type = ParseOutputType(request.params[1].get_str(), pwallet->m_default_address_type);
-        if (output_type == OutputType::NONE) {
+        if (!ParseOutputType(request.params[1].get_str(), output_type)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[1].get_str()));
         }
     }
@@ -259,10 +258,9 @@ UniValue getrawchangeaddress(const JSONRPCRequest& request)
         pwallet->TopUpKeyPool();
     }
 
-    OutputType output_type = pwallet->m_default_change_type != OutputType::NONE ? pwallet->m_default_change_type : pwallet->m_default_address_type;
+    OutputType output_type = pwallet->m_default_change_type != OutputType::CHANGE_AUTO ? pwallet->m_default_change_type : pwallet->m_default_address_type;
     if (!request.params[0].isNull()) {
-        output_type = ParseOutputType(request.params[0].get_str(), output_type);
-        if (output_type == OutputType::NONE) {
+        if (!ParseOutputType(request.params[0].get_str(), output_type)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[0].get_str()));
         }
     }
@@ -1226,8 +1224,7 @@ UniValue addmultisigaddress(const JSONRPCRequest& request)
 
     OutputType output_type = pwallet->m_default_address_type;
     if (!request.params[3].isNull()) {
-        output_type = ParseOutputType(request.params[3].get_str(), output_type);
-        if (output_type == OutputType::NONE) {
+        if (!ParseOutputType(request.params[3].get_str(), output_type)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown address type '%s'", request.params[3].get_str()));
         }
     }
@@ -3180,8 +3177,8 @@ UniValue fundrawtransaction(const JSONRPCRequest& request)
             if (options.exists("changeAddress")) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both changeAddress and address_type options");
             }
-            coinControl.m_change_type = ParseOutputType(options["change_type"].get_str(), pwallet->m_default_change_type);
-            if (coinControl.m_change_type == OutputType::NONE) {
+            coinControl.m_change_type = pwallet->m_default_change_type;
+            if (!ParseOutputType(options["change_type"].get_str(), *coinControl.m_change_type)) {
                 throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Unknown change type '%s'", options["change_type"].get_str()));
             }
         }