Avoid parsing the commandline arguments twice

We parse the arguments independently from QApplication
and initialize the settings before we create QApplication.

Therefore we can parse any setting before creating
QApplication which is required for high DPI support.

We use the QApplication argument parsing to filter out Qt
specific commandline arguments like style.

Change-Id: I83ead87476d99351de6fe4f86c96c39a721af47b
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/app/main.cpp

@@ -58,7 +58,9 @@
 #include <QStandardPaths>
 #include <QTemporaryDir>
 
-#include <memory>
+#include <string>
+#include <vector>
+#include <iterator>
 
 #ifdef ENABLE_QT_BREAKPAD
 #include <qtsystemexceptionhandler.h>
@@ -146,9 +148,22 @@ static void printHelp(const QString &a0)
     displayHelpText(help);
 }
 
+QString applicationDirPath(char *arg = 0)
+{
+    static QString dir;
+
+    if (arg)
+        dir = QFileInfo(QString::fromLocal8Bit(arg)).dir().absolutePath();
+
+    if (QCoreApplication::instance())
+        return QApplication::applicationDirPath();
+
+    return dir;
+}
+
 static QString resourcePath()
 {
-    return QDir::cleanPath(QCoreApplication::applicationDirPath() + '/' + RELATIVE_DATA_PATH);
+    return QDir::cleanPath(applicationDirPath() + '/' + RELATIVE_DATA_PATH);
 }
 
 static inline QString msgCoreLoadFailure(const QString &why)
@@ -238,7 +253,7 @@ static void setupInstallSettings(QString &installSettingspath)
     if (installSettings.contains(kInstallSettingsKey)) {
         QString installSettingsPath = installSettings.value(kInstallSettingsKey).toString();
         if (QDir::isRelativePath(installSettingsPath))
-            installSettingsPath = QCoreApplication::applicationDirPath() + '/' + installSettingsPath;
+            installSettingsPath = applicationDirPath() + '/' + installSettingsPath;
         QSettings::setPath(QSettings::IniFormat, QSettings::SystemScope, installSettingsPath);
     }
 }
@@ -293,23 +308,12 @@ static inline QSettings *userSettings()
     return createUserSettings();
 }
 
-static void setHighDpiEnvironmentVariable(int argc, char **argv)
+static void setHighDpiEnvironmentVariable()
 {
 
     if (Utils::HostOsInfo().isMacHost())
         return;
 
-    std::vector<std::string> arguments(argv, argv + argc);
-    auto it = arguments.begin();
-    QString settingsPath;
-    while (it != arguments.end()) {
-        const QString &arg = QString::fromStdString(*it);
-        it = ++it;
-        if (arg == SETTINGS_OPTION && it != arguments.end())
-            settingsPath = QDir::fromNativeSeparators(QString::fromStdString(*it));
-    }
-    if (!settingsPath.isEmpty())
-        QSettings::setPath(QSettings::IniFormat, QSettings::UserScope, settingsPath);
     std::unique_ptr<QSettings> settings(createUserSettings());
 
     const bool defaultValue = Utils::HostOsInfo().isWindowsHost();
@@ -347,8 +351,6 @@ int main(int argc, char **argv)
 
     Utils::TemporaryDirectory::setMasterTemporaryDirectory(QDir::tempPath() + "/" + Core::Constants::IDE_CASED_ID + "-XXXXXX");
 
-    setHighDpiEnvironmentVariable(argc, argv);
-
     QLoggingCategory::setFilterRules(QLatin1String("qtc.*.debug=false\nqtc.*.info=false"));
 
 #ifdef Q_OS_MAC
@@ -360,9 +362,72 @@ int main(int argc, char **argv)
     setrlimit(RLIMIT_NOFILE, &rl);
 #endif
 
-    SharedTools::QtSingleApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
+    // Manually determine -settingspath and -installsettingspath command line options
-    SharedTools::QtSingleApplication app((QLatin1String(Core::Constants::IDE_DISPLAY_NAME)), argc, argv);
+    // We can't use the regular way of the plugin manager, because that needs to parse plugin meta data
+    // but the settings path can influence which plugins are enabled
+    QString settingsPath;
+    QString installSettingsPath;
+    QStringList customPluginPaths;
+    std::vector<char *> appArguments;
+    bool hasTestOption = false;
 
+    auto it = argv;
+    const auto end = argv + argc;
+    while (it != end) {
+        const auto arg = QString::fromLocal8Bit(*it);
+        const bool hasNext = it + 1 != end;
+
+        if (arg == SETTINGS_OPTION && hasNext) {
+            ++it;
+            settingsPath = QDir::fromNativeSeparators(QString::fromLocal8Bit(*it));
+        } else if (arg == INSTALL_SETTINGS_OPTION && hasNext) {
+            ++it;
+            installSettingsPath = QDir::fromNativeSeparators(QString::fromLocal8Bit(*it));
+        } else if (arg == PLUGINPATH_OPTION && hasNext) {
+            ++it;
+            customPluginPaths += QDir::fromNativeSeparators(QString::fromLocal8Bit(*it));
+        } else {
+            if (arg == TEST_OPTION)
+                hasTestOption = true;
+            appArguments.push_back(*it);
+        }
+        ++it;
+    }
+
+    applicationDirPath(argv[0]);
+
+    QScopedPointer<Utils::TemporaryDirectory> temporaryCleanSettingsDir;
+    if (settingsPath.isEmpty() && hasTestOption) {
+        temporaryCleanSettingsDir.reset(new Utils::TemporaryDirectory("qtc-test-settings"));
+        if (!temporaryCleanSettingsDir->isValid())
+            return 1;
+        settingsPath = temporaryCleanSettingsDir->path();
+    }
+    if (!settingsPath.isEmpty())
+        QSettings::setPath(QSettings::IniFormat, QSettings::UserScope, settingsPath);
+
+    // Must be done before any QSettings class is created
+    QSettings::setDefaultFormat(QSettings::IniFormat);
+    setupInstallSettings(installSettingsPath);
+    // plugin manager takes control of this settings object
+
+    setHighDpiEnvironmentVariable();
+
+    SharedTools::QtSingleApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
+
+    int numberofArguments = static_cast<int>(appArguments.size());
+
+    SharedTools::QtSingleApplication app((QLatin1String(Core::Constants::IDE_DISPLAY_NAME)),
+                                         numberofArguments,
+                                         appArguments.data());
+    const QStringList pluginArguments = app.arguments();
+
+    /*Initialize global settings and resetup install settings with QApplication::applicationDirPath */
+    setupInstallSettings(installSettingsPath);
+    QSettings *settings = userSettings();
+    QSettings *globalSettings = new QSettings(QSettings::IniFormat, QSettings::SystemScope,
+                                              QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR),
+                                              QLatin1String(Core::Constants::IDE_CASED_ID));
     loadFonts();
 
     if (Utils::HostOsInfo().isWindowsHost()
@@ -386,46 +451,6 @@ int main(int argc, char **argv)
 
     app.setAttribute(Qt::AA_UseHighDpiPixmaps);
 
-    // Manually determine -settingspath and -installsettingspath command line options
-    // We can't use the regular way of the plugin manager, because that needs to parse plugin meta data
-    // but the settings path can influence which plugins are enabled
-    QString settingsPath;
-    QString installSettingsPath;
-    QStringList customPluginPaths;
-    QStringList pluginArguments;
-
-    QStringListIterator it(app.arguments());
-    while (it.hasNext()) {
-        const QString &arg = it.next();
-        if (arg == SETTINGS_OPTION && it.hasNext())
-            settingsPath = QDir::fromNativeSeparators(it.next());
-        else if (arg == INSTALL_SETTINGS_OPTION && it.hasNext())
-            installSettingsPath = QDir::fromNativeSeparators(it.next());
-        else if (arg == PLUGINPATH_OPTION && it.hasNext())
-            customPluginPaths += QDir::fromNativeSeparators(it.next());
-        else
-            pluginArguments.append(arg);
-    }
-
-    QScopedPointer<Utils::TemporaryDirectory> temporaryCleanSettingsDir;
-    if (settingsPath.isEmpty() && pluginArguments.contains(TEST_OPTION)) {
-        temporaryCleanSettingsDir.reset(new Utils::TemporaryDirectory("qtc-test-settings"));
-        if (!temporaryCleanSettingsDir->isValid())
-            return 1;
-        settingsPath = temporaryCleanSettingsDir->path();
-    }
-    if (!settingsPath.isEmpty())
-        QSettings::setPath(QSettings::IniFormat, QSettings::UserScope, settingsPath);
-
-    // Must be done before any QSettings class is created
-    QSettings::setDefaultFormat(QSettings::IniFormat);
-    setupInstallSettings(installSettingsPath);
-    // plugin manager takes control of this settings object
-    QSettings *settings = userSettings();
-
-    QSettings *globalSettings = new QSettings(QSettings::IniFormat, QSettings::SystemScope,
-                                              QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR),
-                                              QLatin1String(Core::Constants::IDE_CASED_ID));
     PluginManager pluginManager;
     PluginManager::setPluginIID(QLatin1String("org.qt-project.Qt.QtCreatorPlugin"));
     PluginManager::setGlobalSettings(globalSettings);