wallet: Retrieve ID from loaded DescSPKM directly

Instead of iterating m_spk_managers a DescriptorSPKM has been loaded in
order to get it's ID to compare, have LoadDescriptorSPKM return a
reference to the loaded DescriptorSPKM so it can be queried directly.

Author: achow101

src/wallet/wallet.cpp

@@ -3556,15 +3556,16 @@ void CWallet::ConnectScriptPubKeyManNotifiers()
     }
 }
 
-void CWallet::LoadDescriptorScriptPubKeyMan(uint256 id, WalletDescriptor& desc)
+DescriptorScriptPubKeyMan& CWallet::LoadDescriptorScriptPubKeyMan(uint256 id, WalletDescriptor& desc)
 {
+    DescriptorScriptPubKeyMan* spk_manager;
     if (IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER)) {
-        auto spk_manager = std::unique_ptr<ScriptPubKeyMan>(new ExternalSignerScriptPubKeyMan(*this, desc, m_keypool_size));
-        AddScriptPubKeyMan(id, std::move(spk_manager));
+        spk_manager = new ExternalSignerScriptPubKeyMan(*this, desc, m_keypool_size);
     } else {
-        auto spk_manager = std::unique_ptr<ScriptPubKeyMan>(new DescriptorScriptPubKeyMan(*this, desc, m_keypool_size));
-        AddScriptPubKeyMan(id, std::move(spk_manager));
+        spk_manager = new DescriptorScriptPubKeyMan(*this, desc, m_keypool_size);
     }
+    AddScriptPubKeyMan(id, std::unique_ptr<ScriptPubKeyMan>(spk_manager));
+    return *spk_manager;
 }
 
 void CWallet::SetupDescriptorScriptPubKeyMans(const CExtKey& master_key)

src/wallet/wallet.h

@@ -994,7 +994,7 @@ class CWallet final : public WalletStorage, public interfaces::Chain::Notificati
     void ConnectScriptPubKeyManNotifiers();
 
     //! Instantiate a descriptor ScriptPubKeyMan from the WalletDescriptor and load it
-    void LoadDescriptorScriptPubKeyMan(uint256 id, WalletDescriptor& desc);
+    DescriptorScriptPubKeyMan& LoadDescriptorScriptPubKeyMan(uint256 id, WalletDescriptor& desc);
 
     //! Adds the active ScriptPubKeyMan for the specified type and internal. Writes it to the wallet file
     //! @param[in] id The unique id for the ScriptPubKeyMan

src/wallet/walletdb.cpp

@@ -804,10 +804,10 @@ static DBErrors LoadDescriptorWalletRecords(CWallet* pwallet, DatabaseBatch& bat
             strErr = strprintf("%s\nDetails: %s", strErr, e.what());
             return DBErrors::UNKNOWN_DESCRIPTOR;
         }
-        pwallet->LoadDescriptorScriptPubKeyMan(id, desc);
+        DescriptorScriptPubKeyMan& spkm = pwallet->LoadDescriptorScriptPubKeyMan(id, desc);
 
         // Prior to doing anything with this spkm, verify ID compatibility
-        if (id != pwallet->GetDescriptorScriptPubKeyMan(desc)->GetID()) {
+        if (id != spkm.GetID()) {
             strErr = "The descriptor ID calculated by the wallet differs from the one in DB";
             return DBErrors::CORRUPT;
         }