Merge #14214: convert C-style (void) parameter lists to C++ style ()

3ccfa34b32 convert C-style (void) parameter lists to C++ style () (Arvid Norberg)

Pull request description:

  In C, an empty parameter list, `()`, means the function takes any arguments, and `(void)` means the function does not take any parameters.
  In C++, an empty parameter list means the function does not take any parameters.

  So, C++ still supports `(void)` parameter lists with the same semantics, why change to `()`?

  1. removing the redundant `void` improves signal-to-noise ratio of the code
  2. using `(void)` exposes a rare inconsistency in that a template taking a template `(T)` parameter list, cannot be instantiated with `T=void`

Tree-SHA512: be2897b6c5e474873aa878ed6bac098382cd21866aec33752fe40b089a6331aa6263cae749aba1b4a41e8467f1a47086d32eb74abaf09927fd5a2f44a4b2109a

src/httprpc.cpp

@@ -31,7 +31,7 @@ static const char* WWW_AUTH_HEADER_DATA = "Basic realm=\"jsonrpc\"";
 class HTTPRPCTimer : public RPCTimerBase
 {
 public:
-    HTTPRPCTimer(struct event_base* eventBase, std::function<void(void)>& func, int64_t millis) :
+    HTTPRPCTimer(struct event_base* eventBase, std::function<void()>& func, int64_t millis) :
         ev(eventBase, false, func)
     {
         struct timeval tv;
@@ -53,7 +53,7 @@ public:
     {
         return "HTTP";
     }
-    RPCTimerBase* NewTimer(std::function<void(void)>& func, int64_t millis) override
+    RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis) override
     {
         return new HTTPRPCTimer(base, func, millis);
     }

src/httpserver.cpp

@@ -498,7 +498,7 @@ static void httpevent_callback_fn(evutil_socket_t, short, void* data)
         delete self;
 }
 
-HTTPEvent::HTTPEvent(struct event_base* base, bool _deleteWhenTriggered, const std::function<void(void)>& _handler):
+HTTPEvent::HTTPEvent(struct event_base* base, bool _deleteWhenTriggered, const std::function<void()>& _handler):
     deleteWhenTriggered(_deleteWhenTriggered), handler(_handler)
 {
     ev = event_new(base, -1, 0, httpevent_callback_fn, this);

src/httpserver.h

@@ -134,7 +134,7 @@ public:
      * deleteWhenTriggered deletes this event object after the event is triggered (and the handler called)
      * handler is the handler to call when the event is triggered.
      */
-    HTTPEvent(struct event_base* base, bool deleteWhenTriggered, const std::function<void(void)>& handler);
+    HTTPEvent(struct event_base* base, bool deleteWhenTriggered, const std::function<void()>& handler);
     ~HTTPEvent();
 
     /** Trigger the event. If tv is 0, trigger it immediately. Otherwise trigger it after
@@ -143,7 +143,7 @@ public:
     void trigger(struct timeval* tv);
 
     bool deleteWhenTriggered;
-    std::function<void(void)> handler;
+    std::function<void()> handler;
 private:
     struct event* ev;
 };

src/init.cpp

@@ -691,7 +691,7 @@ static void ThreadImport(std::vector<fs::path> vImportFiles)
  *  Ensure that Bitcoin is running in a usable environment with all
  *  necessary library support.
  */
-static bool InitSanityCheck(void)
+static bool InitSanityCheck()
 {
     if(!ECC_InitSanityCheck()) {
         InitError("Elliptic curve cryptography sanity check failure. Aborting.");

src/key.h

@@ -181,12 +181,12 @@ struct CExtKey {
 };
 
 /** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
-void ECC_Start(void);
+void ECC_Start();
 
 /** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
-void ECC_Stop(void);
+void ECC_Stop();
 
 /** Check that required EC support is available at runtime. */
-bool ECC_InitSanityCheck(void);
+bool ECC_InitSanityCheck();
 
 #endif // BITCOIN_KEY_H

src/qt/bitcoin.cpp

@@ -586,7 +586,7 @@ int main(int argc, char *argv[])
     //   Need to pass name here as CAmount is a typedef (see http://qt-project.org/doc/qt-5/qmetatype.html#qRegisterMetaType)
     //   IMPORTANT if it is no longer a typedef use the normal variant above
     qRegisterMetaType< CAmount >("CAmount");
-    qRegisterMetaType< std::function<void(void)> >("std::function<void(void)>");
+    qRegisterMetaType< std::function<void()> >("std::function<void()>");
 #ifdef ENABLE_WALLET
     qRegisterMetaType<WalletModel*>("WalletModel*");
 #endif

src/qt/macnotificationhandler.h

@@ -19,7 +19,7 @@ public:
     void showNotification(const QString &title, const QString &text);
 
     /** check if OS can handle UserNotifications */
-    bool hasUserNotificationCenterSupport(void);
+    bool hasUserNotificationCenterSupport();
     static MacNotificationHandler *instance();
 };
 

src/qt/rpcconsole.cpp

@@ -101,7 +101,7 @@ class QtRPCTimerBase: public QObject, public RPCTimerBase
 {
     Q_OBJECT
 public:
-    QtRPCTimerBase(std::function<void(void)>& _func, int64_t millis):
+    QtRPCTimerBase(std::function<void()>& _func, int64_t millis):
         func(_func)
     {
         timer.setSingleShot(true);
@@ -111,7 +111,7 @@ public:
     ~QtRPCTimerBase() {}
 private:
     QTimer timer;
-    std::function<void(void)> func;
+    std::function<void()> func;
 };
 
 class QtRPCTimerInterface: public RPCTimerInterface
@@ -119,7 +119,7 @@ class QtRPCTimerInterface: public RPCTimerInterface
 public:
     ~QtRPCTimerInterface() {}
     const char *Name() { return "Qt"; }
-    RPCTimerBase* NewTimer(std::function<void(void)>& func, int64_t millis)
+    RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis)
     {
         return new QtRPCTimerBase(func, millis);
     }

src/rpc/server.cpp

@@ -540,7 +540,7 @@ void RPCUnsetTimerInterface(RPCTimerInterface *iface)
         timerInterface = nullptr;
 }
 
-void RPCRunLater(const std::string& name, std::function<void(void)> func, int64_t nSeconds)
+void RPCRunLater(const std::string& name, std::function<void()> func, int64_t nSeconds)
 {
     if (!timerInterface)
         throw JSONRPCError(RPC_INTERNAL_ERROR, "No timer handler registered for RPC");

src/rpc/server.h

@@ -110,7 +110,7 @@ public:
      * This is needed to cope with the case in which there is no HTTP server, but
      * only GUI RPC console, and to break the dependency of pcserver on httprpc.
      */
-    virtual RPCTimerBase* NewTimer(std::function<void(void)>& func, int64_t millis) = 0;
+    virtual RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis) = 0;
 };
 
 /** Set the factory function for timers */
@@ -124,7 +124,7 @@ void RPCUnsetTimerInterface(RPCTimerInterface *iface);
  * Run func nSeconds from now.
  * Overrides previous timer <name> (if any).
  */
-void RPCRunLater(const std::string& name, std::function<void(void)> func, int64_t nSeconds);
+void RPCRunLater(const std::string& name, std::function<void()> func, int64_t nSeconds);
 
 typedef UniValue(*rpcfn_type)(const JSONRPCRequest& jsonRequest);
 

src/scheduler.cpp

@@ -159,7 +159,7 @@ void SingleThreadedSchedulerClient::MaybeScheduleProcessQueue() {
 }
 
 void SingleThreadedSchedulerClient::ProcessQueue() {
-    std::function<void (void)> callback;
+    std::function<void ()> callback;
     {
         LOCK(m_cs_callbacks_pending);
         if (m_are_callbacks_running) return;
@@ -187,7 +187,7 @@ void SingleThreadedSchedulerClient::ProcessQueue() {
     callback();
 }
 
-void SingleThreadedSchedulerClient::AddToProcessQueue(std::function<void (void)> func) {
+void SingleThreadedSchedulerClient::AddToProcessQueue(std::function<void ()> func) {
     assert(m_pscheduler);
 
     {

src/scheduler.h

@@ -40,7 +40,7 @@ public:
     CScheduler();
     ~CScheduler();
 
-    typedef std::function<void(void)> Function;
+    typedef std::function<void()> Function;
 
     // Call func at/after time t
     void schedule(Function f, boost::chrono::system_clock::time_point t=boost::chrono::system_clock::now());
@@ -99,7 +99,7 @@ private:
     CScheduler *m_pscheduler;
 
     CCriticalSection m_cs_callbacks_pending;
-    std::list<std::function<void (void)>> m_callbacks_pending GUARDED_BY(m_cs_callbacks_pending);
+    std::list<std::function<void ()>> m_callbacks_pending GUARDED_BY(m_cs_callbacks_pending);
     bool m_are_callbacks_running GUARDED_BY(m_cs_callbacks_pending) = false;
 
     void MaybeScheduleProcessQueue();
@@ -114,7 +114,7 @@ public:
      * Practically, this means that callbacks can behave as if they are executed
      * in order by a single thread.
      */
-    void AddToProcessQueue(std::function<void (void)> func);
+    void AddToProcessQueue(std::function<void ()> func);
 
     // Processes all remaining queue members on the calling thread, blocking until queue is empty
     // Must be called after the CScheduler has no remaining processing threads!

src/test/crypto_tests.cpp

@@ -200,7 +200,7 @@ static void TestChaCha20(const std::string &hexkey, uint64_t nonce, uint64_t see
     BOOST_CHECK(out == outres);
 }
 
-static std::string LongTestString(void) {
+static std::string LongTestString() {
     std::string ret;
     for (int i=0; i<200000; i++) {
         ret += (unsigned char)(i);

src/util.cpp

@@ -1248,7 +1248,7 @@ fs::path AbsPathForConfigVal(const fs::path& path, bool net_specific)
     return fs::absolute(path, GetDataDir(net_specific));
 }
 
-int ScheduleBatchPriority(void)
+int ScheduleBatchPriority()
 {
 #ifdef SCHED_BATCH
     const static sched_param param{0};

src/util.h

@@ -347,7 +347,7 @@ std::string CopyrightHolders(const std::string& strPrefix);
  * @return The return value of sched_setschedule(), or 1 on systems without
  * sched_setschedule().
  */
-int ScheduleBatchPriority(void);
+int ScheduleBatchPriority();
 
 namespace util {
 

src/validation.cpp

@@ -4682,7 +4682,7 @@ int VersionBitsTipStateSinceHeight(const Consensus::Params& params, Consensus::D
 
 static const uint64_t MEMPOOL_DUMP_VERSION = 1;
 
-bool LoadMempool(void)
+bool LoadMempool()
 {
     const CChainParams& chainparams = Params();
     int64_t nExpiryTimeout = gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60;
@@ -4759,7 +4759,7 @@ bool LoadMempool(void)
     return true;
 }
 
-bool DumpMempool(void)
+bool DumpMempool()
 {
     int64_t start = GetTimeMicros();