Deprecate QObject::findChildren(const QRegExp &, ...)

Use the overload using QRegularExpression instead.

Change-Id: I1bf468b248c0a3f5b2304b1831379a127093df06
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@qt.io>

src/corelib/kernel/qobject.cpp

@@ -1820,12 +1820,15 @@ void QObject::killTimer(int id)
 /*!
     \fn template<typename T> QList<T> QObject::findChildren(const QRegExp &regExp, Qt::FindChildOptions options) const
     \overload findChildren()
+    \obsolete
 
     Returns the children of this object that can be cast to type T
     and that have names matching the regular expression \a regExp,
     or an empty list if there are no such objects.
     The search is performed recursively, unless \a options specifies the
     option FindDirectChildrenOnly.
+
+    Use the findChildren overload taking a QRegularExpression instead.
 */
 
 /*!

src/corelib/kernel/qobject.h

@@ -176,7 +176,9 @@ public:
     }
 
 #ifndef QT_NO_REGEXP
+#if QT_DEPRECATED_SINCE(5, 13)
     template<typename T>
+    QT_DEPRECATED_X("Use findChildren(const RegularExpression &, ...) instead.")
     inline QList<T> findChildren(const QRegExp &re, Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
     {
         typedef typename std::remove_cv<typename std::remove_pointer<T>::type>::type ObjType;
@@ -186,6 +188,7 @@ public:
         return list;
     }
 #endif
+#endif
 
 #if QT_CONFIG(regularexpression)
     template<typename T>