Merge bitcoin#13769: Mark single-argument constructors "explicit"

1ac3c98 Mark single-argument constructors "explicit" (practicalswift)

Pull request description:

  Mark single-argument constructors `explicit`.

  Rationale:
  * Avoid unexpected implicit promotions.

  From the developer notes:

  > **By default, declare single-argument constructors explicit.**
  > Rationale: This is a precaution to avoid unintended conversions that might arise when single-argument constructors are used as implicit conversion functions.

Tree-SHA512: 7901ed5be808c9d0ecb5ca501e1bc0395987fe1b7941b8548cebac2ff08a14f7dab61fab374a69b9ba29a9295a04245c814325c7f95b97ae558af0780f111dfa

src/interfaces/handler.cpp

@@ -15,7 +15,7 @@ namespace {
 class HandlerImpl : public Handler
 {
 public:
-    HandlerImpl(boost::signals2::connection connection) : m_connection(std::move(connection)) {}
+    explicit HandlerImpl(boost::signals2::connection connection) : m_connection(std::move(connection)) {}
 
     void disconnect() override { m_connection.disconnect(); }
 

src/interfaces/wallet.cpp

@@ -31,7 +31,7 @@ namespace {
 class PendingWalletTxImpl : public PendingWalletTx
 {
 public:
-    PendingWalletTxImpl(CWallet& wallet) : m_wallet(wallet), m_key(&wallet) {}
+    explicit PendingWalletTxImpl(CWallet& wallet) : m_wallet(wallet), m_key(&wallet) {}
 
     const CTransaction& get() override { return *m_tx; }
 
@@ -117,7 +117,7 @@ static WalletTxOut MakeWalletTxOut(CWallet& wallet, const CWalletTx& wtx, int n,
 class WalletImpl : public Wallet
 {
 public:
-    WalletImpl(const std::shared_ptr<CWallet>& wallet) : m_shared_wallet(wallet), m_wallet(*wallet.get()) {}
+    explicit WalletImpl(const std::shared_ptr<CWallet>& wallet) : m_shared_wallet(wallet), m_wallet(*wallet.get()) {}
 
     bool encryptWallet(const SecureString& wallet_passphrase) override
     {

src/key_io.cpp

@@ -24,7 +24,7 @@ class DestinationEncoder : public boost::static_visitor<std::string>
     const CChainParams& m_params;
 
 public:
-    DestinationEncoder(const CChainParams& params) : m_params(params) {}
+    explicit DestinationEncoder(const CChainParams& params) : m_params(params) {}
 
     std::string operator()(const CKeyID& id) const
     {

src/qt/addresstablemodel.cpp

@@ -71,7 +71,7 @@ class AddressTablePriv
     QList<AddressTableEntry> cachedAddressTable;
     AddressTableModel *parent;
 
-    AddressTablePriv(AddressTableModel *_parent):
+    explicit AddressTablePriv(AddressTableModel *_parent):
         parent(_parent) {}
 
     void refreshAddressTable(interfaces::Wallet& wallet)

src/qt/rpcconsole.cpp

@@ -82,7 +82,7 @@ class RPCExecutor : public QObject
 {
     Q_OBJECT
 public:
-    RPCExecutor(interfaces::Node& node) : m_node(node) {}
+    explicit RPCExecutor(interfaces::Node& node) : m_node(node) {}
 
 public Q_SLOTS:
     void request(const QString &command, const QString &walletID);

src/qt/transactiontablemodel.cpp

@@ -60,7 +60,7 @@ struct TxLessThan
 class TransactionTablePriv
 {
 public:
-    TransactionTablePriv(TransactionTableModel *_parent) :
+    explicit TransactionTablePriv(TransactionTableModel *_parent) :
         parent(_parent)
     {
     }

src/test/miner_tests.cpp

@@ -29,7 +29,7 @@ BOOST_FIXTURE_TEST_SUITE(miner_tests, TestingSetup)
 // BOOST_CHECK_EXCEPTION predicates to check the specific validation error
 class HasReason {
 public:
-    HasReason(const std::string& reason) : m_reason(reason) {}
+    explicit HasReason(const std::string& reason) : m_reason(reason) {}
     bool operator() (const std::runtime_error& e) const {
         return std::string(e.what()).find(m_reason) != std::string::npos;
     };

src/test/validation_block_tests.cpp

@@ -23,7 +23,7 @@ BOOST_FIXTURE_TEST_SUITE(validation_block_tests, RegtestingSetup)
 struct TestSubscriber : public CValidationInterface {
     uint256 m_expected_tip;
 
-    TestSubscriber(uint256 tip) : m_expected_tip(tip) {}
+    explicit TestSubscriber(uint256 tip) : m_expected_tip(tip) {}
 
     void UpdatedBlockTip(const CBlockIndex* pindexNew, const CBlockIndex* pindexFork, bool fInitialDownload) override
     {