Fixes a crash when setting focus on a widget with a focus proxy.

When the focus proxy widget doesn't have InputMethodEnabled attribute set we
shouldn't try to set an input context on it.

Reviewed-by: Simon Hausmann

2 files changed, 50 insertions, 6 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 1cb3883..81a9a80 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -3088,7 +3088,8 @@ void QWidgetPrivate::setEnabled_helper(bool enable)
         QWidget *focusWidget = effectiveFocusWidget();
         QInputContext *qic = focusWidget->d_func()->inputContext();
         if (enable) {
-            qic->setFocusWidget(focusWidget);
+            if (focusWidget->testAttribute(Qt::WA_InputMethodEnabled))
+                qic->setFocusWidget(focusWidget);
         } else {
             qic->reset();
             qic->setFocusWidget(0);
@@ -10357,17 +10358,22 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
 #ifndef QT_NO_IM
         QWidget *focusWidget = d->effectiveFocusWidget();
         QInputContext *ic = 0;
-        if (on && !internalWinId() && testAttribute(Qt::WA_InputMethodEnabled) && hasFocus()) {
+        if (on && !internalWinId() && hasFocus()
+            && focusWidget->testAttribute(Qt::WA_InputMethodEnabled)) {
             ic = focusWidget->d_func()->inputContext();
-            ic->reset();
-            ic->setFocusWidget(0);
+            if (ic) {
+                ic->reset();
+                ic->setFocusWidget(0);
+            }
         }
         if (!qApp->testAttribute(Qt::AA_DontCreateNativeWidgetSiblings) && parentWidget())
             parentWidget()->d_func()->enforceNativeChildren();
         if (on && !internalWinId() && testAttribute(Qt::WA_WState_Created))
             d->createWinId();
-        if (ic && isEnabled())
+        if (ic && isEnabled() && focusWidget->isEnabled()
+            && focusWidget->testAttribute(Qt::WA_InputMethodEnabled)) {
             ic->setFocusWidget(focusWidget);
+        }
 #endif //QT_NO_IM
         break;
     }
@@ -10404,7 +10410,8 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
         if (!ic && (!on || hasFocus()))
             ic = focusWidget->d_func()->inputContext();
         if (ic) {
-            if (on && hasFocus() && ic->focusWidget() != focusWidget && isEnabled()) {
+            if (on && hasFocus() && ic->focusWidget() != focusWidget && isEnabled()
+                && focusWidget->testAttribute(Qt::WA_InputMethodEnabled)) {
                 ic->setFocusWidget(focusWidget);
             } else if (!on && ic->focusWidget() == focusWidget) {
                 ic->reset();
diff --git a/tests/auto/qinputcontext/tst_qinputcontext.cpp b/tests/auto/qinputcontext/tst_qinputcontext.cpp
index 50f9140..644b463 100644
--- a/tests/auto/qinputcontext/tst_qinputcontext.cpp
+++ b/tests/auto/qinputcontext/tst_qinputcontext.cpp
@@ -68,6 +68,7 @@ private slots:
     void requestSoftwareInputPanel();
     void closeSoftwareInputPanel();
     void selections();
+    void focusProxy();
 };
 
 void tst_QInputContext::maximumTextLength()
@@ -248,5 +249,41 @@ void tst_QInputContext::selections()
     QCOMPARE(le.inputMethodQuery(Qt::ImAnchorPosition).toInt(), 5);
 }
 
+void tst_QInputContext::focusProxy()
+{
+    QWidget toplevel(0, Qt::X11BypassWindowManagerHint); toplevel.setObjectName("toplevel");
+    QWidget w(&toplevel); w.setObjectName("w");
+    QWidget proxy(&w); proxy.setObjectName("proxy");
+    QWidget proxy2(&w); proxy2.setObjectName("proxy2");
+    w.setFocusProxy(&proxy);
+    w.setAttribute(Qt::WA_InputMethodEnabled);
+    toplevel.show();
+    QApplication::setActiveWindow(&toplevel);
+    QTest::qWaitForWindowShown(&toplevel);
+    w.setFocus();
+    w.setAttribute(Qt::WA_NativeWindow); // we shouldn't crash!
+
+    proxy.setAttribute(Qt::WA_InputMethodEnabled);
+    proxy2.setAttribute(Qt::WA_InputMethodEnabled);
+
+    proxy2.setFocus();
+    w.setFocus();
+
+    QInputContext *gic = qApp->inputContext();
+    QVERIFY(gic);
+    qDebug() << gic->focusWidget() << &proxy;
+    QCOMPARE(gic->focusWidget(), &proxy);
+
+    // then change the focus proxy and check that input context is valid
+    QVERIFY(w.hasFocus());
+    QVERIFY(proxy.hasFocus());
+    QVERIFY(!proxy2.hasFocus());
+    w.setFocusProxy(&proxy2);
+    QVERIFY(!w.hasFocus());
+    QVERIFY(proxy.hasFocus());
+    QVERIFY(!proxy2.hasFocus());
+    QCOMPARE(gic->focusWidget(), &proxy);
+}
+
 QTEST_MAIN(tst_QInputContext)
 #include "tst_qinputcontext.moc"