ExtensionSystem: Consistently use nullptr

Fixed by clang-tidy modernize-use-nullptr.

Change-Id: Ibf3797854e8f15940d363695ce30cc4558ed1ab8
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/extensionsystem/iplugin.h

@@ -59,7 +59,7 @@ public:
     virtual ShutdownFlag aboutToShutdown() { return SynchronousShutdown; }
     virtual QObject *remoteCommand(const QStringList & /* options */,
                                    const QString & /* workingDirectory */,
-                                   const QStringList & /* arguments */) { return 0; }
+                                   const QStringList & /* arguments */) { return nullptr; }
     virtual QList<QObject *> createTestObjects() const;
 
     PluginSpec *pluginSpec() const;

src/libs/extensionsystem/plugindetailsview.h

@@ -43,7 +43,7 @@ class EXTENSIONSYSTEM_EXPORT PluginDetailsView : public QWidget
     Q_OBJECT
 
 public:
-    PluginDetailsView(QWidget *parent = 0);
+    PluginDetailsView(QWidget *parent = nullptr);
     ~PluginDetailsView() override;
 
     void update(PluginSpec *spec);

src/libs/extensionsystem/pluginerroroverview.h

@@ -44,7 +44,7 @@ class EXTENSIONSYSTEM_EXPORT PluginErrorOverview : public QDialog
     Q_OBJECT
 
 public:
-    explicit PluginErrorOverview(QWidget *parent = 0);
+    explicit PluginErrorOverview(QWidget *parent = nullptr);
     ~PluginErrorOverview() override;
 
 private:

src/libs/extensionsystem/pluginerrorview.h

@@ -41,7 +41,7 @@ class EXTENSIONSYSTEM_EXPORT PluginErrorView : public QWidget
     Q_OBJECT
 
 public:
-    PluginErrorView(QWidget *parent = 0);
+    PluginErrorView(QWidget *parent = nullptr);
     ~PluginErrorView() override;
 
     void update(PluginSpec *spec);

src/libs/extensionsystem/pluginmanager.h

@@ -67,7 +67,7 @@ public:
             if (T *result = qobject_cast<T *>(obj))
                 return result;
         }
-        return 0;
+        return nullptr;
     }
     template <typename T, typename Predicate> static T *getObject(Predicate predicate)
     {
@@ -117,7 +117,7 @@ public:
 
     static bool testRunRequested();
 
-    static void profilingReport(const char *what, const PluginSpec *spec = 0);
+    static void profilingReport(const char *what, const PluginSpec *spec = nullptr);
 
     static QString platformName();
 

src/libs/extensionsystem/pluginview.h

@@ -48,7 +48,7 @@ class EXTENSIONSYSTEM_EXPORT PluginView : public QWidget
     Q_OBJECT
 
 public:
-    explicit PluginView(QWidget *parent = 0);
+    explicit PluginView(QWidget *parent = nullptr);
     ~PluginView() override;
 
     PluginSpec *currentPlugin() const;