In reply to TC_2017:
You might have run into a few different tool issues. You’ll need to contact your tool vendor for support.
[A1] The result should be 4’b1111.
[A2] Try using %d formats instead of %p.
[A3] I’m not able to reproduce your constrained failure. It would help to provide a complete example.
c and d are part of the constraint expression; they are are constrained in some sense. But their context is independent of the rest of the expression, so it will be a signed comparison. But its result is 1-bit unsigned as you mention.