C++20 Round 5: typedef -> using, IMPLEMENT_SERIALIZE macro cleanup

- Convert 15 typedef declarations to C++11 using aliases across 12 files:
  script.h (valtype, CTxDestination), serialize.h (CSerializeData),
  keystore.h (KeyMap, ScriptMap, CryptedKeyMap), sync.h (CCriticalSection,
  CWaitableCriticalSection), sync.cpp (LockStack), key.h (CPrivKey, CSecret),
  crypter.h (CKeyingMaterial), allocators.h (SecureString), main.h (MapPrevTx),
  wallet.h (mapValue_t, removed duplicate), miner.cpp (TxPriority),
  kernel.cpp (MapModifierCheckpoints)
- Remove redundant duplicate mapValue_t typedef in wallet.h
- IMPLEMENT_SERIALIZE macro: replace assert() warning suppression with
  [[maybe_unused]] attributes on fGetSize/fWrite/fRead/nSerSize

src/allocators.h

@@ -254,7 +254,7 @@ struct zero_after_free_allocator : public std::allocator<T>
 };
 
 // This is exactly like std::string, but with a custom allocator.
-typedef std::basic_string<char, std::char_traits<char>, secure_allocator<char> > SecureString;
+using SecureString = std::basic_string<char, std::char_traits<char>, secure_allocator<char>>;
 
 static inline SecureString MakeSecureString(const std::string& value)
 {

src/crypter.h

@@ -80,7 +80,7 @@ public:
 
 };
 
-typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
+using CKeyingMaterial = std::vector<unsigned char, secure_allocator<unsigned char>>;
 
 /** Encryption/decryption context with key information */
 class CCrypter

src/kernel.cpp

@@ -14,7 +14,7 @@ extern unsigned int nTargetSpacing;
 // Set to 20-minute for production network
 //unsigned int nModifierInterval = MODIFIER_INTERVAL;
 
-typedef std::map<int, unsigned int> MapModifierCheckpoints;
+using MapModifierCheckpoints = std::map<int, unsigned int>;
 
 // Hard checkpoints of stake modifiers to ensure they are deterministic
 static std::map<int, unsigned int> mapStakeModifierCheckpoints = {

src/key.h

@@ -99,9 +99,8 @@ public:
 
 // secure_allocator is defined in allocators.h
 // CPrivKey is a serialized private key, with all parameters included (279 bytes)
-typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
-// CSecret is a serialization of just the secret parameter (32 bytes)
-typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
+using CPrivKey = std::vector<unsigned char, secure_allocator<unsigned char>>;
+using CSecret = std::vector<unsigned char, secure_allocator<unsigned char>>;
 
 /** An encapsulated secp256k1 elliptic-curve key (public and/or private). */
 class CKey

src/keystore.h

@@ -44,8 +44,8 @@ public:
     }
 };
 
-typedef std::map<CKeyID, std::pair<CSecret, bool> > KeyMap;
-typedef std::map<CScriptID, CScript > ScriptMap;
+using KeyMap = std::map<CKeyID, std::pair<CSecret, bool>>;
+using ScriptMap = std::map<CScriptID, CScript>;
 
 /** Basic key store, that keeps keys in an address->secret map */
 class CBasicKeyStore : public CKeyStore
@@ -94,7 +94,7 @@ public:
     virtual bool GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const;
 };
 
-typedef std::map<CKeyID, std::pair<CPubKey, std::vector<unsigned char> > > CryptedKeyMap;
+using CryptedKeyMap = std::map<CKeyID, std::pair<CPubKey, std::vector<unsigned char>>>;
 
 /** Keystore which keeps the private keys encrypted.
  * It derives from the basic key store, which is used if no encryption is active.

src/main.h

@@ -475,7 +475,7 @@ public:
     }
 };
 
-typedef std::map<COutPoint, CUtxoEntry> MapPrevTx;
+using MapPrevTx = std::map<COutPoint, CUtxoEntry>;
 
 /** The basic transaction that is broadcasted on the network and contained in
  * blocks.  A transaction can contain multiple inputs and outputs.

src/miner.cpp

@@ -50,7 +50,7 @@ uint64_t nLastBlockSize = 0;
 int64_t nLastCoinStakeSearchInterval = 0;
  
 // We want to sort transactions by priority and fee, so:
-typedef std::tuple<double, double, CTransaction*> TxPriority;
+using TxPriority = std::tuple<double, double, CTransaction*>;
 class TxPriorityCompare
 {
     bool byFee;

src/script.h

@@ -16,7 +16,7 @@
 #include "keystore.h"
 #include "bignum.h"
 
-typedef std::vector<unsigned char> valtype;
+using valtype = std::vector<unsigned char>;
 
 class CTransaction;
 
@@ -51,7 +51,7 @@ public:
  *  * CScriptID: TX_SCRIPTHASH destination
  *  A CTxDestination is the internal data type encoded in a CTrianglesAddress
  */
-typedef std::variant<CNoDestination, CKeyID, CScriptID> CTxDestination;
+using CTxDestination = std::variant<CNoDestination, CKeyID, CScriptID>;
 
 const char* GetTxnOutputType(TxnOutType t);
 

src/serialize.h

@@ -59,12 +59,11 @@ enum
     unsigned int GetSerializeSize(int nType, int nVersion) const  \
     {                                           \
         CSerActionGetSerializeSize ser_action;  \
-        const bool fGetSize = true;             \
-        const bool fWrite = false;              \
-        const bool fRead = false;               \
+        [[maybe_unused]] const bool fGetSize = true; \
+        [[maybe_unused]] const bool fWrite = false;  \
+        [[maybe_unused]] const bool fRead = false;   \
         unsigned int nSerSize = 0;              \
         ser_streamplaceholder s;                \
-        assert(fGetSize||fWrite||fRead); /* suppress warning */ \
         s.nType = nType;                        \
         s.nVersion = nVersion;                  \
         {statements}                            \
@@ -74,22 +73,20 @@ enum
     void Serialize(Stream& s, int nType, int nVersion) const  \
     {                                           \
         CSerActionSerialize ser_action;         \
-        const bool fGetSize = false;            \
-        const bool fWrite = true;               \
-        const bool fRead = false;               \
-        unsigned int nSerSize = 0;              \
-        assert(fGetSize||fWrite||fRead); /* suppress warning */ \
+        [[maybe_unused]] const bool fGetSize = false; \
+        [[maybe_unused]] const bool fWrite = true;   \
+        [[maybe_unused]] const bool fRead = false;   \
+        [[maybe_unused]] unsigned int nSerSize = 0;  \
         {statements}                            \
     }                                           \
     template<typename Stream>                   \
     void Unserialize(Stream& s, int nType, int nVersion)  \
     {                                           \
         CSerActionUnserialize ser_action;       \
-        const bool fGetSize = false;            \
-        const bool fWrite = false;              \
-        const bool fRead = true;                \
-        unsigned int nSerSize = 0;              \
-        assert(fGetSize||fWrite||fRead); /* suppress warning */ \
+        [[maybe_unused]] const bool fGetSize = false; \
+        [[maybe_unused]] const bool fWrite = false;  \
+        [[maybe_unused]] const bool fRead = true;    \
+        [[maybe_unused]] unsigned int nSerSize = 0;  \
         {statements}                            \
     }
 
@@ -705,7 +702,7 @@ struct ser_streamplaceholder
 
 
 
-typedef std::vector<char, zero_after_free_allocator<char> > CSerializeData;
+using CSerializeData = std::vector<char, zero_after_free_allocator<char>>;
 
 /** Double ended buffer combining vector and stream-like interfaces.
  *

src/sync.cpp

@@ -46,7 +46,7 @@ private:
     int sourceLine;
 };
 
-typedef std::vector< std::pair<void*, CLockLocation> > LockStack;
+using LockStack = std::vector<std::pair<void*, CLockLocation>>;
 
 static std::mutex dd_mutex;
 static std::map<std::pair<void*, void*>, LockStack> lockorders;

src/sync.h

@@ -9,10 +9,10 @@
 #include <condition_variable>
 
 /** Recursive mutex: supports recursive locking, but no waiting */
-typedef std::recursive_mutex CCriticalSection;
+using CCriticalSection = std::recursive_mutex;
 
 /** Plain mutex: supports waiting but not recursive locking */
-typedef std::mutex CWaitableCriticalSection;
+using CWaitableCriticalSection = std::mutex;
 
 #ifdef DEBUG_LOCKORDER
 void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);

src/wallet.h

@@ -29,7 +29,7 @@ class COutput;
 class CCoinControl;
 
 //typedef std::map<CKeyID, CStealthKeyMetadata> StealthKeyMetaMap;
-typedef std::map<std::string, std::string> mapValue_t;
+using mapValue_t = std::map<std::string, std::string>;
 
 /** (client) version numbers for particular wallet features */
 enum class WalletFeature : int
@@ -359,8 +359,6 @@ public:
 };
 
 
-typedef std::map<std::string, std::string> mapValue_t;
-
 
 static void ReadOrderPos(int64_t& nOrderPos, mapValue_t& mapValue)
 {