I realize I can't put 5V in to an input pin, but I have a pin I'm going to configure as an output, which will be wired to one side of a normally open switch. The switch has 5V across it, so I just realized that when it is manually closed it'll short the 5V (supplied from the Pi) to the pin. I'm assuming this won't be ok, but wanted to check.
I guess I can use a diode to block the voltage, but I'm worried about the voltage drop across the diode, as the switch is supposed to be 5V and is already only getting 3.2V from the GPIO pin. The diode may drop it below the threshold where it will trigger.
My other alternative is the use a transistor to switch 5V from the Pi to the switch.