Hi Dave,
Thanks for the explanation - very interesting! Is the mechanism you describe a “feature” of the way in which system functions are implemented in Questa rather than something I could find in the standard? The text in section 18.5.12 says
“Functions shall be called before constraints are solved, and their return values shall be treated as state variables”
This corresponds to the results I see if I replace $countones with my own countones member function (either along the lines of the one in section 18.5.12 or one that simply returns the sum of all bits in a single statement).
Regards,
Dave