Merge remote-tracking branch 'origin/5.13' into dev

Change-Id: Ia279fc4a8226626041c772902a07b2f90f37b53b

2 files changed, 28 insertions, 1 deletions

diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 625790abb8..b70c61e351 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -46,6 +46,7 @@
 #include "qcoreevent.h"
 #include "qeventloop.h"
 #endif
+#include "qmetaobject.h"
 #include "qcorecmdlineargs_p.h"
 #include <qdatastream.h>
 #include <qdebug.h>
@@ -952,6 +953,10 @@ bool QCoreApplication::isSetuidAllowed()
     Sets the attribute \a attribute if \a on is true;
     otherwise clears the attribute.
 
+    \note Some application attributes must be set \b before creating a
+    QCoreApplication instance. Refer to the Qt::ApplicationAttribute
+    documentation for more information.
+
     \sa testAttribute()
 */
 void QCoreApplication::setAttribute(Qt::ApplicationAttribute attribute, bool on)
@@ -960,6 +965,27 @@ void QCoreApplication::setAttribute(Qt::ApplicationAttribute attribute, bool on)
         QCoreApplicationPrivate::attribs |= 1 << attribute;
     else
         QCoreApplicationPrivate::attribs &= ~(1 << attribute);
+    if (Q_UNLIKELY(qApp)) {
+        switch (attribute) {
+            case Qt::AA_EnableHighDpiScaling:
+            case Qt::AA_DisableHighDpiScaling:
+            case Qt::AA_PluginApplication:
+            case Qt::AA_UseDesktopOpenGL:
+            case Qt::AA_UseOpenGLES:
+            case Qt::AA_UseSoftwareOpenGL:
+            case Qt::AA_ShareOpenGLContexts:
+#ifdef QT_BOOTSTRAPPED
+                qWarning("Attribute %d must be set before QCoreApplication is created.",
+                         attribute);
+#else
+                qWarning("Attribute Qt::%s must be set before QCoreApplication is created.",
+                         QMetaEnum::fromType<Qt::ApplicationAttribute>().valueToKey(attribute));
+#endif
+                break;
+            default:
+                break;
+        }
+    }
 }
 
 /*!
diff --git a/src/corelib/kernel/qmetaobject.h b/src/corelib/kernel/qmetaobject.h
index 10b14a7e03..fcd92afd89 100644
--- a/src/corelib/kernel/qmetaobject.h
+++ b/src/corelib/kernel/qmetaobject.h
@@ -230,7 +230,8 @@ public:
 
     template<typename T> static QMetaEnum fromType() {
         Q_STATIC_ASSERT_X(QtPrivate::IsQEnumHelper<T>::Value,
-                          "QMetaEnum::fromType only works with enums declared as Q_ENUM or Q_FLAG");
+                          "QMetaEnum::fromType only works with enums declared as "
+                          "Q_ENUM, Q_ENUM_NS, Q_FLAG or Q_FLAG_NS");
         const QMetaObject *metaObject = qt_getEnumMetaObject(T());
         const char *name = qt_getEnumName(T());
         return metaObject->enumerator(metaObject->indexOfEnumerator(name));