Unfortunately I can no longer reproduce that problem already :-(
At the time, my project was out of DATA space, and after I discovered a
workaround to the un-assigned problem, I spent the remainder of that day
freeing up more DATA space. The work around I found was to move the
function call a bit earlier in the function, above an assignment which was
occurring directly above it. That assignment was to a global char variable
in XDATA (and was assigning it a constant value 0). When I did that, the
code generated properly again. After my day of free'ing DATA space, now I
find today that I can put the function back and the problem doesn't reappear
:-( It's unlikely the compiler thought the value in that parameter-slot was
already correct, this function is only ever called once with that particular
set of parameters. In the future, I'll do better at creating something
people can reproduce the problem with.
While I'm writing a message, I might as well ask another question (but I'll
start another thread since it's unrelated).