Deprecate vtkVectorOperators.h use vtkVector.h instead

Common/DataModel/vtkVectorOperators.h

@@ -4,12 +4,21 @@
 #ifndef vtkVectorOperators_h
 #define vtkVectorOperators_h
 
-// This set of operators enhance the vtkVector classes, allowing various
-// operator overloads one might expect.
+// This file used to set operators that enhance the vtkVector classes.
+// We reimplemented them directly in vtkVector.h, and this file is now only kept
+// for deprecation purpose and should be removed once we hit the deprecation milestone.
+#include "vtkDeprecation.h" // For VTK_DEPRECATED_IN_9_4_0
 #include "vtkVector.h"
 
 VTK_ABI_NAMESPACE_BEGIN
 
+namespace
+{
+VTK_DEPRECATED_IN_9_4_0("vtkVectorOperators.h is deprecated use vtkVector.h instead")
+constexpr int vtkVectorOperators_h_is_deprecated = 0;
+constexpr int please_dont_use_vtkVectorOperators_h = vtkVectorOperators_h_is_deprecated;
+};
+
 VTK_ABI_NAMESPACE_END
 #endif
 // VTK-HeaderTest-Exclude: vtkVectorOperators.h