Your thinking is right - a switch  with a constant  required at that point would
be useless.

No, it's not meant to be a constant. The items in the "case" lines need to be
constants, of course.

Are you sure it's the switch line  it doesn't like? Compilers can get their
error messages a bit out of step sometimes.

You've obviously posted an indicative bit of code, not the real thing. I think
it might be better to post the real code.