If the solver is attempting to optimize a cell with a function in it,
and the input cell to the function has an integer constraint on it, the
solver won't do anything.

For example:

set A1 = 1
set B1 = "=dummy(A1)"

create a function in a module like so:

public function dummy( x as integer ) as integer
dummy = x * 10
end function

optimize for the maximum value of B1, constraining A1 like so:
A1 = 1
A1 <= 10
A1 is an integer

...And the solver does nothing. What is the proper way to do this?