Merge remote branch 'staging/master' into refactor

Conflicts:
	src/opengl/qgl_qpa.cpp
	src/plugins/platforms/glxconvenience/qglxconvenience.cpp
	src/plugins/platforms/platforms.pro
	src/plugins/platforms/wayland/qwaylandwindow.cpp
	src/plugins/platforms/xcb/qxcbwindow.cpp
	src/plugins/platforms/xcb/qxcbwindow.h
	src/plugins/platforms/xcb/qxcbwindowsurface.cpp
	src/widgets/kernel/qwidget_qpa.cpp
	tests/auto/qvariant/tst_qvariant.cpp

6 files changed, 128 insertions, 23 deletions

diff --git a/tools/uilib/abstractformbuilder.cpp b/tools/uilib/abstractformbuilder.cpp
index a221b6c748..612126c88f 100644
--- a/tools/uilib/abstractformbuilder.cpp
+++ b/tools/uilib/abstractformbuilder.cpp
@@ -52,6 +52,7 @@
 #include <QtCore/QDir>
 #include <QtCore/QQueue>
 #include <QtCore/QHash>
+#include <QtCore/QPair>
 #include <QtCore/qdebug.h>
 #include <QtCore/QCoreApplication>
 
@@ -143,44 +144,97 @@ QAbstractFormBuilder::~QAbstractFormBuilder()
 {
 }
 
+// Return UI file version from attribute 'version="4.0"'
+static QPair<int, int> uiVersion(const QString &attr)
+{
+    const QStringList versions = attr.split(QLatin1Char('.'), QString::SkipEmptyParts);
+    if (versions.size() >= 2) {
+        bool okMajor, okMinor;
+        const int majorVersion = versions.at(0).toInt(&okMajor);
+        const int minorVersion = versions.at(1).toInt(&okMinor);
+        if (okMajor &&  okMinor)
+            return QPair<int, int>(majorVersion, minorVersion);
+    }
+    return QPair<int, int>(-1, -1);
+}
+
+static inline QString msgXmlError(const QXmlStreamReader &reader)
+{
+    return QCoreApplication::translate("QAbstractFormBuilder", "An error has occurred while reading the UI file at line %1, column %2: %3")
+                                       .arg(reader.lineNumber()).arg(reader.columnNumber()).arg(reader.errorString());
+}
+
+// Read and check the  version and the (optional) language attribute
+// of an <ui> element and leave reader positioned at <ui>.
+static bool inline readUiAttributes(QXmlStreamReader &reader, const QString &language, QString *errorMessage)
+{
+    const QString uiElement = QLatin1String("ui");
+    // Read up to first element
+    while (!reader.atEnd()) {
+        switch (reader.readNext()) {
+        case QXmlStreamReader::Invalid:
+            *errorMessage = msgXmlError(reader);
+            return false;
+        case QXmlStreamReader::StartElement:
+            if (reader.name().compare(uiElement, Qt::CaseInsensitive) == 0) {
+                const QString versionAttribute = QLatin1String("version");
+                const QString languageAttribute = QLatin1String("language");
+                const QXmlStreamAttributes attributes = reader.attributes();
+                if (attributes.hasAttribute(versionAttribute)) {
+                    const QString versionString = attributes.value(versionAttribute).toString();
+                    if (uiVersion(versionString).first < 4) {
+                        *errorMessage = QCoreApplication::translate("QAbstractFormBuilder", "This file was created using Designer from Qt-%1 and cannot be read.")
+                                .arg(versionString);
+                        return false;
+                    } // version error
+                }     // has version
+                if (attributes.hasAttribute(languageAttribute)) {
+                    // Check on optional language (Jambi)
+                    const QString formLanguage = attributes.value(languageAttribute).toString();
+                    if (!formLanguage.isEmpty() && formLanguage.compare(language, Qt::CaseInsensitive)) {
+                        *errorMessage = QCoreApplication::translate("QAbstractFormBuilder", "This file cannot be read because it was created using %1.").arg(formLanguage);
+                        return false;
+                    } // language error
+                }    // has language
+                return true;
+            }  // <ui> matched
+            break;
+        default:
+            break;
+        }
+    }
+    // No <ui> found.
+    *errorMessage = QCoreApplication::translate("QAbstractFormBuilder",  "Invalid UI file: The root element <ui> is missing.");
+    return false;
+}
+
 /*!
     \fn QWidget *QAbstractFormBuilder::load(QIODevice *device, QWidget *parent)
 
     Loads an XML representation of a widget from the given \a device,
     and constructs a new widget with the specified \a parent.
 
-    \sa save()
+    \sa save(), errorString()
 */
 QWidget *QAbstractFormBuilder::load(QIODevice *dev, QWidget *parentWidget)
 {
-    QXmlStreamReader reader;
-    reader.setDevice(dev);
-    DomUI ui;
-    bool initialized = false;
-
-    const QString uiElement = QLatin1String("ui");
-    while (!reader.atEnd()) {
-        if (reader.readNext() == QXmlStreamReader::StartElement) {
-            if (reader.name().compare(uiElement, Qt::CaseInsensitive) == 0) {
-                ui.read(reader);
-                initialized = true;
-            } else {
-                reader.raiseError(QCoreApplication::translate("QAbstractFormBuilder", "Unexpected element <%1>").arg(reader.name().toString()));
-            }
-        }
+    QXmlStreamReader reader(dev);
+    d->m_errorString.clear();
+    if (!readUiAttributes(reader, d->m_language, &d->m_errorString)) {
+        uiLibWarning(d->m_errorString);
+        return false;
     }
+    DomUI ui;
+    ui.read(reader);
     if (reader.hasError()) {
-        uiLibWarning(QCoreApplication::translate("QAbstractFormBuilder", "An error has occurred while reading the UI file at line %1, column %2: %3")
-                                .arg(reader.lineNumber()).arg(reader.columnNumber())
-                                .arg(reader.errorString()));
-        return 0;
-    }
-    if (!initialized) {
-        uiLibWarning(QCoreApplication::translate("QAbstractFormBuilder", "Invalid UI file: The root element <ui> is missing."));
+        d->m_errorString = msgXmlError(reader);
+        uiLibWarning(d->m_errorString);
         return 0;
     }
 
     QWidget *widget = create(&ui, parentWidget);
+    if (!widget && d->m_errorString.isEmpty())
+        d->m_errorString = QCoreApplication::translate("QAbstractFormBuilder", "Invalid UI file");
     return widget;
 }
 
@@ -3085,4 +3139,16 @@ bool QAbstractFormBuilder::isScriptingEnabled() const
 #endif
 }
 
+/*!
+    Returns a human-readable description of the last error occurred in load().
+
+    \since 5.0
+    \sa load()
+*/
+
+QString QAbstractFormBuilder::errorString() const
+{
+    return d->m_errorString;
+}
+
 QT_END_NAMESPACE
diff --git a/tools/uilib/abstractformbuilder.h b/tools/uilib/abstractformbuilder.h
index 9d53e2d4b7..13208721ff 100644
--- a/tools/uilib/abstractformbuilder.h
+++ b/tools/uilib/abstractformbuilder.h
@@ -127,6 +127,8 @@ public:
     void setScriptingEnabled(bool enabled);
     bool isScriptingEnabled() const;
 
+    QString errorString() const;
+
 protected:
 //
 // load
diff --git a/tools/uilib/container.h b/tools/uilib/container.h
index 89df461e02..f0d89faa08 100644
--- a/tools/uilib/container.h
+++ b/tools/uilib/container.h
@@ -65,6 +65,13 @@ public:
     virtual void addWidget(QWidget *widget) = 0;
     virtual void insertWidget(int index, QWidget *widget) = 0;
     virtual void remove(int index) = 0;
+
+    virtual bool canAddWidget() const
+    // ### Qt6 remove body, provided in Qt5 for source compatibility to Qt4.
+         { return true; }
+    virtual bool canRemove(int index) const
+    // ### Qt6 remove body, provided in Qt5 for source compatibility to Qt4.
+         { Q_UNUSED(index); return true; }
 };
 Q_DECLARE_EXTENSION_INTERFACE(QDesignerContainerExtension, "com.trolltech.Qt.Designer.Container")
 
diff --git a/tools/uilib/container.qdoc b/tools/uilib/container.qdoc
index d9310515d3..f8e0670811 100644
--- a/tools/uilib/container.qdoc
+++ b/tools/uilib/container.qdoc
@@ -170,3 +170,30 @@
 
     \sa addWidget(), insertWidget()
 */
+
+/*!
+    \fn bool QDesignerContainerExtension::canAddWidget() const
+
+    Returns whether a widget can be added. This determines whether
+    the context menu options to add or insert pages are enabled.
+
+    This should return false for containers that have a single, fixed
+    page, for example QScrollArea or QDockWidget.
+
+    \since 5.0
+    \sa addWidget(), canRemove()
+*/
+
+/*!
+    \fn bool QDesignerContainerExtension::canRemove(int index) const
+
+    Returns whether the widget at the given \a index can be removed.
+    This determines whether the context menu option to remove the current
+    page is enabled.
+
+    This should return false for containers that have a single, fixed
+    page, for example QScrollArea or QDockWidget.
+
+    \since 5.0
+    \sa remove(), canAddWidget()
+*/
diff --git a/tools/uilib/formbuilderextra.cpp b/tools/uilib/formbuilderextra.cpp
index bca0c595e5..264be6e461 100644
--- a/tools/uilib/formbuilderextra.cpp
+++ b/tools/uilib/formbuilderextra.cpp
@@ -87,6 +87,7 @@ QFormBuilderExtra::CustomWidgetData::CustomWidgetData(const DomCustomWidget *dcw
 QFormBuilderExtra::QFormBuilderExtra() :
     m_defaultMargin(INT_MIN),
     m_defaultSpacing(INT_MIN),
+    m_language(QLatin1String("c++")),
     m_layoutWidget(false),
     m_resourceBuilder(0),
     m_textBuilder(0)
diff --git a/tools/uilib/formbuilderextra_p.h b/tools/uilib/formbuilderextra_p.h
index a5e2029391..777776039d 100644
--- a/tools/uilib/formbuilderextra_p.h
+++ b/tools/uilib/formbuilderextra_p.h
@@ -180,6 +180,8 @@ public:
     int m_defaultMargin;
     int m_defaultSpacing;
     QDir m_workingDirectory;
+    QString m_errorString;
+    QString m_language;
 
 private:
     void clearResourceBuilder();