Properly block modified signal during Database destruction (#6438)

fixes #6393

src/core/ModifiableObject.cpp

@@ -0,0 +1,65 @@
+/*
+ *  Copyright (C) 2021 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ModifiableObject.h"
+
+namespace
+{
+    template <typename T> T findParent(const QObject* obj)
+    {
+        if (!obj) {
+            return {};
+        }
+
+        auto p = obj->parent();
+        while (p) {
+            auto casted = qobject_cast<T>(p);
+            if (casted) {
+                return casted;
+            }
+            p = p->parent();
+        }
+        return {};
+    }
+} // namespace
+
+bool ModifiableObject::modifiedSignalEnabled() const
+{
+    auto p = this;
+    while (p) {
+        if (!p->m_emitModified) {
+            return false;
+        }
+        p = findParent<ModifiableObject*>(p);
+    }
+    return true;
+}
+
+void ModifiableObject::setEmitModified(bool value)
+{
+    if (m_emitModified != value) {
+        m_emitModified = value;
+        emit emitModifiedChanged(m_emitModified);
+    }
+}
+
+void ModifiableObject::emitModified()
+{
+    if (modifiedSignalEnabled()) {
+        emit modified();
+    }
+}