Merge #12119: [wallet] use P2WPKH change output if any destination is P2WPKH or P2WSH

596c446 [wallet] use P2WPKH change output if any destination is P2WPKH or P2WSH (Sjors Provoost)

Pull request description:

  If `-changetype` is not explicitly set, then regardless of `-addresstype`, the wallet will use a ~`bech32` change address~ `P2WPKH` change output if any destination is `P2WPKH` or `P2WSH`.

  This seems more intuitive to me and more in line with the spirit of [BIP-69](https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki).

  When combined with #11991 a QT user could opt to use `bech32` exclusively without having to figure out how to launch with `-changetype=bech32`, although so would #11937.

Tree-SHA512: 9238d3ccd1f3be8dfdd43444ccf45d6bdc6584ced3172a3045f3ecfec4a7cc8999db0cdb76ae49236492a84e6dbf3a1fdf18544d3eaf6d518e1f8bd241db33e7

1 files changed, 3 insertions, 2 deletions

diff --git a/src/qt/paymentserver.cpp b/src/qt/paymentserver.cpp
index dc729649b8..bc69d4f945 100644
--- a/src/qt/paymentserver.cpp
+++ b/src/qt/paymentserver.cpp
@@ -643,8 +643,9 @@ void PaymentServer::fetchPaymentACK(CWallet* wallet, const SendCoinsRecipient& r
         // use for change. Despite an actual payment and not change, this is a close match:
         // it's the output type we use subject to privacy issues, but not restricted by what
         // other software supports.
-        wallet->LearnRelatedScripts(newKey, g_change_type);
-        CTxDestination dest = GetDestinationForKey(newKey, g_change_type);
+        const OutputType change_type = g_change_type != OUTPUT_TYPE_NONE ? g_change_type : g_address_type;
+        wallet->LearnRelatedScripts(newKey, change_type);
+        CTxDestination dest = GetDestinationForKey(newKey, change_type);
         wallet->SetAddressBook(dest, strAccount, "refund");
 
         CScript s = GetScriptForDestination(dest);