bugfix: Mark CNoDestination and PubKeyDestination constructor explicit

This should fix the bug reported in
https://github.com/bitcoin/bitcoin/pull/28246#discussion_r1371640502,
which caused the GUI to not detect the destination type of recipients,
thus picking the wrong change destination type.

Also, add missing lifetimebound attribute to a getter method.

src/addresstype.h

@@ -15,15 +15,16 @@
 #include <variant>
 #include <vector>
 
-class CNoDestination {
+class CNoDestination
+{
 private:
     CScript m_script;
 
 public:
     CNoDestination() = default;
-    CNoDestination(const CScript& script) : m_script(script) {}
+    explicit CNoDestination(const CScript& script) : m_script(script) {}
 
-    const CScript& GetScript() const { return m_script; }
+    const CScript& GetScript() const LIFETIMEBOUND { return m_script; }
 
     friend bool operator==(const CNoDestination& a, const CNoDestination& b) { return a.GetScript() == b.GetScript(); }
     friend bool operator<(const CNoDestination& a, const CNoDestination& b) { return a.GetScript() < b.GetScript(); }
@@ -34,7 +35,7 @@ private:
     CPubKey m_pubkey;
 
 public:
-    PubKeyDestination(const CPubKey& pubkey) : m_pubkey(pubkey) {}
+    explicit PubKeyDestination(const CPubKey& pubkey) : m_pubkey(pubkey) {}
 
     const CPubKey& GetPubKey() const LIFETIMEBOUND { return m_pubkey; }
 

src/bench/wallet_create_tx.cpp

@@ -94,13 +94,14 @@ static void WalletCreateTx(benchmark::Bench& bench, const OutputType output_type
     }
 
     // Generate destinations
-    CScript dest = GetScriptForDestination(getNewDestination(wallet, output_type));
+    const auto dest{getNewDestination(wallet, output_type)};
 
     // Generate chain; each coinbase will have two outputs to fill-up the wallet
     const auto& params = Params();
+    const CScript coinbase_out{GetScriptForDestination(dest)};
     unsigned int chain_size = 5000; // 5k blocks means 10k UTXO for the wallet (minus 200 due COINBASE_MATURITY)
     for (unsigned int i = 0; i < chain_size; ++i) {
-        generateFakeBlock(params, test_setup->m_node, wallet, dest);
+        generateFakeBlock(params, test_setup->m_node, wallet, coinbase_out);
     }
 
     // Check available balance

src/qt/walletmodel.cpp

@@ -187,8 +187,7 @@ WalletModel::SendCoinsReturn WalletModel::prepareTransaction(WalletModelTransact
             setAddress.insert(rcp.address);
             ++nAddresses;
 
-            CScript scriptPubKey = GetScriptForDestination(DecodeDestination(rcp.address.toStdString()));
+            CRecipient recipient{DecodeDestination(rcp.address.toStdString()), rcp.amount, rcp.fSubtractFeeFromAmount};
-            CRecipient recipient = {scriptPubKey, rcp.amount, rcp.fSubtractFeeFromAmount};
             vecSend.push_back(recipient);
 
             total += rcp.amount;

src/wallet/test/spend_tests.cpp

@@ -78,7 +78,7 @@ BOOST_FIXTURE_TEST_CASE(wallet_duplicated_preset_inputs_test, TestChain100Setup)
 
     // Try to create a tx that spends more than what preset inputs + wallet selected inputs are covering for.
     // The wallet can cover up to 200 BTC, and the tx target is 299 BTC.
-    std::vector<CRecipient> recipients = {{GetScriptForDestination(*Assert(wallet->GetNewDestination(OutputType::BECH32, "dummy"))),
+    std::vector<CRecipient> recipients{{*Assert(wallet->GetNewDestination(OutputType::BECH32, "dummy")),
                                            /*nAmount=*/299 * COIN, /*fSubtractFeeFromAmount=*/true}};
     CCoinControl coin_control;
     coin_control.m_allow_other_inputs = true;

src/wallet/test/wallet_tests.cpp

@@ -605,7 +605,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoinsTest, ListCoinsTestingSetup)
     // returns the coin associated with the change address underneath the
     // coinbaseKey pubkey, even though the change address has a different
     // pubkey.
-    AddTx(CRecipient{GetScriptForRawPubKey({}), 1 * COIN, /*subtract_fee=*/false});
+    AddTx(CRecipient{PubKeyDestination{{}}, 1 * COIN, /*subtract_fee=*/false});
     {
         LOCK(wallet->cs_wallet);
         list = ListCoins(*wallet);