Designer: Add a code for legacy custom signals/slots

For a very old form that was generated pre Qt 4 times,
there was no signals/slots section containing custom
signals/slots of the form. Generate it now when it seems
missing.

Fixes: QTBUG-99421
Change-Id: Ib9e373a65bf7e96cb98b549a81d00fba25de6982
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
(cherry picked from commit efc959e96695a49a0763a6a307e656e664c1e943)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 96 insertions, 48 deletions

diff --git a/src/designer/src/components/signalsloteditor/signalsloteditor.cpp b/src/designer/src/components/signalsloteditor/signalsloteditor.cpp
index 28bb2c736..4b90e9dd1 100644
--- a/src/designer/src/components/signalsloteditor/signalsloteditor.cpp
+++ b/src/designer/src/components/signalsloteditor/signalsloteditor.cpp
@@ -33,6 +33,7 @@
 
 #include <metadatabase_p.h>
 #include <qdesigner_formwindowcommand_p.h>
+#include <signalslotdialog_p.h>
 
 #include <QtDesigner/private/ui4_p.h>
 #include <QtDesigner/abstractformwindow.h>
@@ -373,6 +374,21 @@ void SignalSlotEditor::fromUi(const DomConnections *connections, QWidget *parent
     if (connections == nullptr)
         return;
 
+    // For old forms, that were saved before Qt 4 times, there was no <slots>
+    // section inside ui file. Currently, when we specify custom signals or slots
+    // for the form, we add them into the <slots> section. For all signals / slots
+    // inside <slots> section uic creates string-based connections.
+    // In order to fix old forms, we detect if a signal or slot used inside connection
+    // is a custom (fake) one, like it's being done inside SignalSlotDialog.
+    // In case of a fake signal / slot we register it inside meta data base, so that
+    // the next save will add a missing <slots> section.
+    QStringList existingSlots, existingSignals;
+    SignalSlotDialog::existingMethodsFromMemberSheet(m_form_window->core(), parent,
+                                                     existingSlots, existingSignals);
+    QStringList fakeSlots, fakeSignals;
+    SignalSlotDialog::fakeMethodsFromMetaDataBase(m_form_window->core(), parent,
+                                                  fakeSlots, fakeSignals);
+
     setBackground(parent);
     clear();
     const auto &list = connections->elementConnection();
@@ -404,14 +420,29 @@ void SignalSlotEditor::fromUi(const DomConnections *connections, QWidget *parent
             }
         }
 
+        const QString sourceSignal = dom_con->elementSignal();
+        if (source == parent && !existingSignals.contains(sourceSignal)
+                && !fakeSignals.contains(sourceSignal)) {
+            fakeSignals.append(sourceSignal);
+        }
+
+        const QString destSlot = dom_con->elementSlot();
+        if (destination == parent && !existingSlots.contains(destSlot)
+                && !fakeSlots.contains(destSlot)) {
+            fakeSlots.append(destSlot);
+        }
+
+
         SignalSlotConnection *con = new SignalSlotConnection(this);
 
         con->setEndPoint(EndPoint::Source, source, sp);
         con->setEndPoint(EndPoint::Target, destination, tp);
-        con->setSignal(dom_con->elementSignal());
-        con->setSlot(dom_con->elementSlot());
+        con->setSignal(sourceSignal);
+        con->setSlot(destSlot);
         addConnection(con);
     }
+    SignalSlotDialog::fakeMethodsToMetaDataBase(m_form_window->core(), parent,
+                                                fakeSlots, fakeSignals);
 }
 
 static bool skipWidget(const QWidget *w)
diff --git a/src/designer/src/lib/shared/signalslotdialog.cpp b/src/designer/src/lib/shared/signalslotdialog.cpp
index 65297030d..28cf2703e 100644
--- a/src/designer/src/lib/shared/signalslotdialog.cpp
+++ b/src/designer/src/lib/shared/signalslotdialog.cpp
@@ -58,14 +58,14 @@ QT_BEGIN_NAMESPACE
 static const char *signatureRegExp = "^[\\w+_]+\\(([\\w+:]\\*?,?)*\\)$";
 static const char *methodNameRegExp = "^[\\w+_]+$";
 
-static  QStandardItem *createEditableItem(const QString &text)
+static QStandardItem *createEditableItem(const QString &text)
 {
     QStandardItem *rc = new QStandardItem(text);
     rc->setFlags(Qt::ItemIsEnabled|Qt::ItemIsEditable|Qt::ItemIsSelectable);
     return rc;
 }
 
-static  QStandardItem *createDisabledItem(const QString &text)
+static QStandardItem *createDisabledItem(const QString &text)
 {
     QStandardItem *rc = new QStandardItem(text);
     Qt::ItemFlags flags = rc->flags();
@@ -73,48 +73,6 @@ static  QStandardItem *createDisabledItem(const QString &text)
     return rc;
 }
 
-static void fakeMethodsFromMetaDataBase(QDesignerFormEditorInterface *core, QObject *o, QStringList &slotList, QStringList &signalList)
-{
-    slotList.clear();
-    signalList.clear();
-    if (qdesigner_internal::MetaDataBase *metaDataBase = qobject_cast<qdesigner_internal::MetaDataBase *>(core->metaDataBase()))
-        if (const qdesigner_internal::MetaDataBaseItem *item = metaDataBase->metaDataBaseItem(o)) {
-            slotList = item->fakeSlots();
-            signalList = item->fakeSignals();
-        }
-}
-
-static void fakeMethodsToMetaDataBase(QDesignerFormEditorInterface *core, QObject *o, const QStringList &slotList, const QStringList &signalList)
-{
-    if (qdesigner_internal::MetaDataBase *metaDataBase = qobject_cast<qdesigner_internal::MetaDataBase *>(core->metaDataBase())) {
-        qdesigner_internal::MetaDataBaseItem *item = metaDataBase->metaDataBaseItem(o);
-        Q_ASSERT(item);
-        item->setFakeSlots(slotList);
-        item->setFakeSignals(signalList);
-    }
-}
-
-static void existingMethodsFromMemberSheet(QDesignerFormEditorInterface *core,
-                                           QObject *o,
-                                           QStringList &slotList, QStringList &signalList)
-{
-    slotList.clear();
-    signalList.clear();
-
-    QDesignerMemberSheetExtension *msheet = qt_extension<QDesignerMemberSheetExtension*>(core->extensionManager(), o);
-    if (!msheet)
-        return;
-
-    for (int i = 0, count = msheet->count(); i < count; ++i)
-        if (msheet->isVisible(i)) {
-            if (msheet->isSlot(i))
-                slotList += msheet->signature(i);
-            else
-                if (msheet->isSignal(i))
-                    signalList += msheet->signature(i);
-        }
-}
-
 namespace {
     // Internal helper class: A Delegate that validates using RegExps and additionally checks
     // on closing (adds missing parentheses).
@@ -175,9 +133,15 @@ namespace {
                   const QStringList &newFakeSlots, const QStringList &newFakeSignals);
 
         void undo() override
-        { fakeMethodsToMetaDataBase(core(), m_object, m_oldFakeSlots, m_oldFakeSignals); }
+        {
+            qdesigner_internal::SignalSlotDialog::fakeMethodsToMetaDataBase(core(), m_object,
+                                                  m_oldFakeSlots, m_oldFakeSignals);
+        }
         void redo() override
-        { fakeMethodsToMetaDataBase(core(), m_object, m_newFakeSlots, m_newFakeSignals); }
+        {
+            qdesigner_internal::SignalSlotDialog::fakeMethodsToMetaDataBase(core(), m_object,
+                                                  m_newFakeSlots, m_newFakeSignals);
+        }
 
     private:
         QObject *m_object;
@@ -512,6 +476,51 @@ bool SignalSlotDialog::editPromotedClass(QDesignerFormEditorInterface *core, con
     return true;
 }
 
+void SignalSlotDialog::fakeMethodsFromMetaDataBase(QDesignerFormEditorInterface *core, QObject *o,
+                                                   QStringList &slotList, QStringList &signalList)
+{
+    slotList.clear();
+    signalList.clear();
+    if (auto *metaDB = qobject_cast<qdesigner_internal::MetaDataBase *>(core->metaDataBase())) {
+        if (const auto *item = metaDB->metaDataBaseItem(o)) {
+            slotList = item->fakeSlots();
+            signalList = item->fakeSignals();
+        }
+    }
+}
+
+void SignalSlotDialog::fakeMethodsToMetaDataBase(QDesignerFormEditorInterface *core, QObject *o,
+                                                 const QStringList &slotList,
+                                                 const QStringList &signalList)
+{
+    if (auto *metaDB = qobject_cast<qdesigner_internal::MetaDataBase *>(core->metaDataBase())) {
+        if (auto *item = metaDB->metaDataBaseItem(o)) {
+            item->setFakeSlots(slotList);
+            item->setFakeSignals(signalList);
+        }
+    }
+}
+
+void SignalSlotDialog::existingMethodsFromMemberSheet(QDesignerFormEditorInterface *core, QObject *o,
+                                                      QStringList &slotList, QStringList &signalList)
+{
+    slotList.clear();
+    signalList.clear();
+
+    auto *msheet = qt_extension<QDesignerMemberSheetExtension*>(core->extensionManager(), o);
+    if (!msheet)
+        return;
+
+    for (qsizetype i = 0, count = msheet->count(); i < count; ++i) {
+        if (msheet->isVisible(i)) {
+            if (msheet->isSlot(i))
+                slotList += msheet->signature(i);
+            else if (msheet->isSignal(i))
+                signalList += msheet->signature(i);
+        }
+    }
+}
+
 }
 
 QT_END_NAMESPACE
diff --git a/src/designer/src/lib/shared/signalslotdialog_p.h b/src/designer/src/lib/shared/signalslotdialog_p.h
index e0253bcc5..6bcd32a75 100644
--- a/src/designer/src/lib/shared/signalslotdialog_p.h
+++ b/src/designer/src/lib/shared/signalslotdialog_p.h
@@ -140,6 +140,14 @@ public:
     // Edit fake methods of a promoted class stored in WidgetDataBase on a base class instance.
     static bool editPromotedClass(QDesignerFormEditorInterface *core, QObject *baseObject, QWidget *parent = nullptr, FocusMode m = FocusSlots);
 
+    static void fakeMethodsFromMetaDataBase(QDesignerFormEditorInterface *core, QObject *o,
+                                            QStringList &slotList, QStringList &signalList);
+    static void fakeMethodsToMetaDataBase(QDesignerFormEditorInterface *core, QObject *o,
+                                          const QStringList &slotList, const QStringList &signalList);
+    static void existingMethodsFromMemberSheet(QDesignerFormEditorInterface *core, QObject *o,
+                                               QStringList &slotList, QStringList &signalList);
+
+
 private slots:
     void slotCheckSignature(const QString &signature, bool *ok);