Merge #16578: Do not pass in command line arguments to QApplication

a2714a5c69 Give QApplication dummy arguments (Andrew Chow)

Pull request description:

  QApplication takes the command line arguments and parses them itself for some [built in command line arguments](https://doc.qt.io/qt-5/qapplication.html#QApplication) that it has. We don't want any of those built in arguments, so instead give it dummy arguments.

  To test, you can use the `-reverse` option. Without this patch, everything will appear right-to-left; things that were on the left side will be on the right and everything is right aligned.

  After this patch, `-reverse` will now give a startup error since we do not support this argument.

ACKs for top commit:
  laanwj:
    ACK a2714a5c69
  hebasto:
    ACK a2714a5c69
  fanquake:
    ACK a2714a5c69 - Have tested that arguments like `-reverse` are no longer being passed through and result in an error.

Tree-SHA512: 983bd948ca6999f895b6662b58c37e33af7ed61fdd600c6b4623febb87ec06a92c66e3b3300783530110cc711902793ef82d751d7f563696c4c3a8416b2b1f51

src/qt/bitcoin.cpp

@@ -169,8 +169,11 @@ void BitcoinCore::shutdown()
     }
 }
 
-BitcoinApplication::BitcoinApplication(interfaces::Node& node, int &argc, char **argv):
-    QApplication(argc, argv),
+static int qt_argc = 1;
+static const char* qt_argv = "bitcoin-qt";
+
+BitcoinApplication::BitcoinApplication(interfaces::Node& node):
+    QApplication(qt_argc, const_cast<char **>(&qt_argv)),
     coreThread(nullptr),
     m_node(node),
     optionsModel(nullptr),
@@ -433,7 +436,7 @@ int GuiMain(int argc, char* argv[])
     QApplication::setAttribute(Qt::AA_DontShowIconsInMenus);
 #endif
 
-    BitcoinApplication app(*node, argc, argv);
+    BitcoinApplication app(*node);
 
     // Register meta types used for QMetaObject::invokeMethod
     qRegisterMetaType< bool* >();

src/qt/bitcoin.h

@@ -56,7 +56,7 @@ class BitcoinApplication: public QApplication
 {
     Q_OBJECT
 public:
-    explicit BitcoinApplication(interfaces::Node& node, int &argc, char **argv);
+    explicit BitcoinApplication(interfaces::Node& node);
     ~BitcoinApplication();
 
 #ifdef ENABLE_WALLET

src/qt/test/test_main.cpp

@@ -68,7 +68,7 @@ int main(int argc, char *argv[])
 
     // Don't remove this, it's needed to access
     // QApplication:: and QCoreApplication:: in the tests
-    BitcoinApplication app(*node, argc, argv);
+    BitcoinApplication app(*node);
     app.setApplicationName("Bitcoin-Qt-test");
 
     AppTests app_tests(app);