diff --git a/src/corelib/global/qtypeinfo.h b/src/corelib/global/qtypeinfo.h
index 90ac8c6a0c41c7037154903a8a44ada6c9709443..7fee613f8922ffde30275363a96db442978d43c7 100644
--- a/src/corelib/global/qtypeinfo.h
+++ b/src/corelib/global/qtypeinfo.h
@@ -201,13 +201,22 @@ Q_DECLARE_TYPEINFO_BODY(QFlags<T>, Q_PRIMITIVE_TYPE);
    where 'type' is the name of the type to specialize.  NOTE: shared
    types must define a member-swap, and be defined in the same
    namespace as Qt for this to work.
+
+   If the type was already released without Q_DECLARE_SHARED applied,
+   _and_ without an explicit Q_DECLARE_TYPEINFO(type, Q_MOVABLE_TYPE),
+   then use Q_DECLARE_SHARED_NOT_MOVABLE_UNTIL_QT6(type) to mark the
+   type shared (incl. swap()), without marking it movable (which
+   would change the memory layout of QList, a BiC change.
 */
 
-#define Q_DECLARE_SHARED(TYPE)                                          \
-Q_DECLARE_TYPEINFO(TYPE, Q_MOVABLE_TYPE); \
+#define Q_DECLARE_SHARED_IMPL(TYPE, FLAGS) \
+Q_DECLARE_TYPEINFO(TYPE, FLAGS); \
 inline void swap(TYPE &value1, TYPE &value2) \
     Q_DECL_NOEXCEPT_EXPR(noexcept(value1.swap(value2))) \
 { value1.swap(value2); }
+#define Q_DECLARE_SHARED(TYPE) Q_DECLARE_SHARED_IMPL(TYPE, Q_MOVABLE_TYPE)
+#define Q_DECLARE_SHARED_NOT_MOVABLE_UNTIL_QT6(TYPE) \
+                               Q_DECLARE_SHARED_IMPL(TYPE, QT_VERSION >= QT_VERSION_CHECK(6,0,0) ? Q_MOVABLE_TYPE : Q_COMPLEX_TYPE)
 
 /*
    QTypeInfo primitive specializations