Given the rulings found here and here:
As with most bonus actions, you choose the timing, so the Shield Master shove can come before or after the Attack action. - Crawford
If you have the Shield Master feat, what would happen if you shoved a creature using your bonus action from the feat, and then had no movement left and so could not reach it to perform the Attack action?
Would you simply forfeit your action entirely, or, worst case scenario, would you have to use it against yourself?