5 files changed, 38 insertions, 3 deletions

diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index d957dda162..a983dc6fde 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -153,12 +153,19 @@ void QMenuPrivate::init()
         scroll->scrollFlags = QMenuPrivate::QMenuScroller::ScrollNone;
     }
 
-    setPlatformMenu(QGuiApplicationPrivate::platformTheme()->createPlatformMenu());
     sloppyState.initialize(q);
     delayState.initialize(q);
     mousePopupDelay = q->style()->styleHint(QStyle::SH_Menu_SubMenuPopupDelay, 0, q);
 }
 
+QPlatformMenu *QMenuPrivate::createPlatformMenu()
+{
+    Q_Q(QMenu);
+    if (platformMenu.isNull())
+        q->setPlatformMenu(QGuiApplicationPrivate::platformTheme()->createPlatformMenu());
+    return platformMenu.data();
+}
+
 void QMenuPrivate::setPlatformMenu(QPlatformMenu *menu)
 {
     Q_Q(QMenu);
diff --git a/src/widgets/widgets/qmenu_mac.mm b/src/widgets/widgets/qmenu_mac.mm
index fef1eb2cf4..f9f3ad08dc 100644
--- a/src/widgets/widgets/qmenu_mac.mm
+++ b/src/widgets/widgets/qmenu_mac.mm
@@ -80,11 +80,12 @@ inline QPlatformNativeInterface::NativeResourceForIntegrationFunction resolvePla
 */
 NSMenu *QMenu::toNSMenu()
 {
+    Q_D(QMenu);
     // Call into the cocoa platform plugin: qMenuToNSMenu(platformMenu())
     QPlatformNativeInterface::NativeResourceForIntegrationFunction function = resolvePlatformFunction("qmenutonsmenu");
     if (function) {
         typedef void* (*QMenuToNSMenuFunction)(QPlatformMenu *platformMenu);
-        return reinterpret_cast<NSMenu *>(reinterpret_cast<QMenuToNSMenuFunction>(function)(platformMenu()));
+        return reinterpret_cast<NSMenu *>(reinterpret_cast<QMenuToNSMenuFunction>(function)(d->createPlatformMenu()));
     }
     return nil;
 }
@@ -98,11 +99,12 @@ NSMenu *QMenu::toNSMenu()
 */
 void QMenu::setAsDockMenu()
 {
+    Q_D(QMenu);
     // Call into the cocoa platform plugin: setDockMenu(platformMenu())
     QPlatformNativeInterface::NativeResourceForIntegrationFunction function = resolvePlatformFunction("setdockmenu");
     if (function) {
         typedef void (*SetDockMenuFunction)(QPlatformMenu *platformMenu);
-        reinterpret_cast<SetDockMenuFunction>(function)(platformMenu());
+        reinterpret_cast<SetDockMenuFunction>(function)(d->createPlatformMenu());
     }
 }
 
diff --git a/src/widgets/widgets/qmenu_p.h b/src/widgets/widgets/qmenu_p.h
index 2b0dc482da..3166e6f6cd 100644
--- a/src/widgets/widgets/qmenu_p.h
+++ b/src/widgets/widgets/qmenu_p.h
@@ -286,6 +286,7 @@ public:
             delete platformMenu.data();
     }
     void init();
+    QPlatformMenu *createPlatformMenu();
     void setPlatformMenu(QPlatformMenu *menu);
     void syncPlatformMenu();
 #ifdef Q_OS_OSX
diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index a77c0f9753..63fe09f77e 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -1192,6 +1192,10 @@ QPlatformMenu *QMenuBarPrivate::getPlatformMenu(QAction *action)
     QPlatformMenu *platformMenu = action->menu()->platformMenu();
     if (!platformMenu && platformMenuBar) {
         platformMenu = platformMenuBar->createMenu();
+        // QPlatformMenuBar::createMenu() was introduced in Qt 5.7. Not all third party
+        // platform themes are using it, so fallback to QPlatformTheme::createPlatformMenu().
+        if (!platformMenu)
+            platformMenu = QGuiApplicationPrivate::platformTheme()->createPlatformMenu();
         if (platformMenu)
             action->menu()->setPlatformMenu(platformMenu);
     }
diff --git a/tests/auto/widgets/widgets/qmenubar/tst_qmenubar.cpp b/tests/auto/widgets/widgets/qmenubar/tst_qmenubar.cpp
index ca58dc1247..475ce2a317 100644
--- a/tests/auto/widgets/widgets/qmenubar/tst_qmenubar.cpp
+++ b/tests/auto/widgets/widgets/qmenubar/tst_qmenubar.cpp
@@ -131,6 +131,8 @@ private slots:
     void cornerWidgets();
     void taskQTBUG53205_crashReparentNested();
 
+    void platformMenu();
+
 protected slots:
     void onSimpleActivated( QAction*);
     void onComplexActionTriggered();
@@ -1487,6 +1489,25 @@ void tst_QMenuBar::taskQTBUG53205_crashReparentNested()
     testMenus.actions[0]->trigger();
 }
 
+// QTBUG-56526
+void tst_QMenuBar::platformMenu()
+{
+    QMenuBar menuBar;
+    QPlatformMenuBar *platformMenuBar = menuBar.platformMenuBar();
+    if (!platformMenuBar)
+        QSKIP("No platform menubar implementation available on this platform.");
+
+    // QMenu must not create a platform menu instance at creation time, because
+    // on Unity the type of the platform menu instance must be different (QGtk3Menu
+    // vs. QDbusPlatformMenu) depending on whether the menu is in the global menubar
+    // or a standalone context menu.
+    QMenu *menu = new QMenu(&menuBar);
+    QVERIFY(!menu->platformMenu());
+
+    menuBar.addMenu(menu);
+    QVERIFY(menu->platformMenu());
+}
+
 void tst_QMenuBar::slotForTaskQTBUG53205()
 {
     QWidget *parent = taskQTBUG53205MenuBar->parentWidget();