Return UFVK from `CWallet::GenerateNewUnifiedSpendingKey`

The only place we were using the returned Unified Spending Key was in a
test, where we immediately converted it to a UFVK.

Co-authored-by: Kris Nuttycombe <kris@nutty.land>

src/wallet/gtest/test_wallet.cpp

@@ -2200,14 +2200,15 @@ TEST(WalletTests, GenerateUnifiedAddress) {
     EXPECT_EQ(uaResult, expected);
 
     // Create an account, then generate an address for that account.
-    auto skpair = wallet.GenerateNewUnifiedSpendingKey();
-    uaResult = wallet.GenerateUnifiedAddress(skpair.second, {ReceiverType::P2PKH, ReceiverType::Sapling});
+    auto ufvkpair = wallet.GenerateNewUnifiedSpendingKey();
+    auto ufvk = ufvkpair.first;
+    auto account = ufvkpair.second;
+    uaResult = wallet.GenerateUnifiedAddress(account, {ReceiverType::P2PKH, ReceiverType::Sapling});
     auto ua = std::get_if<std::pair<libzcash::UnifiedAddress, libzcash::diversifier_index_t>>(&uaResult);
     EXPECT_NE(ua, nullptr);
 
     auto uaSaplingReceiver = ua->first.GetSaplingReceiver();
     EXPECT_TRUE(uaSaplingReceiver.has_value());
-    auto ufvk = skpair.first.ToFullViewingKey();
     EXPECT_EQ(uaSaplingReceiver.value(), ufvk.GetSaplingKey().value().Address(ua->second));
 
     auto u4r = wallet.FindUnifiedAddressByReceiver(uaSaplingReceiver.value());

src/wallet/rpcwallet.cpp

@@ -3057,8 +3057,8 @@ UniValue z_getnewaccount(const UniValue& params, bool fHelp)
     EnsureWalletIsUnlocked();
 
     // Generate the new account.
-    auto skNew = pwalletMain->GenerateNewUnifiedSpendingKey();
-    const auto& account = skNew.second;
+    auto ufvkNew = pwalletMain->GenerateNewUnifiedSpendingKey();
+    const auto& account = ufvkNew.second;
 
     UniValue result(UniValue::VOBJ);
     result.pushKV("account", (uint64_t)account);

src/wallet/wallet.cpp

@@ -477,7 +477,7 @@ libzcash::transparent::AccountKey CWallet::GetLegacyAccountKey() const {
 }
 
 
-std::pair<ZcashdUnifiedSpendingKey, libzcash::AccountId> CWallet::GenerateNewUnifiedSpendingKey() {
+std::pair<UnifiedFullViewingKey, libzcash::AccountId> CWallet::GenerateNewUnifiedSpendingKey() {
     AssertLockHeld(cs_wallet);
 
     if (!mnemonicHDChain.has_value()) {
@@ -488,17 +488,17 @@ std::pair<ZcashdUnifiedSpendingKey, libzcash::AccountId> CWallet::GenerateNewUni
     CHDChain& hdChain = mnemonicHDChain.value();
     while (true) {
         auto accountId = hdChain.GetAccountCounter();
-        auto usk = GenerateUnifiedSpendingKeyForAccount(accountId);
+        auto generated = GenerateUnifiedSpendingKeyForAccount(accountId);
         hdChain.IncrementAccountCounter();
 
-        if (usk.has_value()) {
+        if (generated.has_value()) {
             // Update the persisted chain information
             if (fFileBacked && !CWalletDB(strWalletFile).WriteMnemonicHDChain(hdChain)) {
                 throw std::runtime_error(
                         "CWallet::GenerateNewUnifiedSpendingKey(): Writing HD chain model failed");
             }
 
-            return std::make_pair(usk.value(), accountId);
+            return std::make_pair(generated.value().ToFullViewingKey(), accountId);
         }
     }
 }

src/wallet/wallet.h

@@ -1480,7 +1480,7 @@ public:
 
     //! Generate the unified spending key from the wallet's mnemonic seed
     //! for the next unused account identifier.
-    std::pair<libzcash::ZcashdUnifiedSpendingKey, libzcash::AccountId>
+    std::pair<libzcash::UnifiedFullViewingKey, libzcash::AccountId>
         GenerateNewUnifiedSpendingKey();
 
     //! Generate the unified spending key for the specified ZIP-32/BIP-44