Is using a short to create a synthetic long shares of stock really legal/allowed/common? If so, seems like a loophole a truck could be driven through that I'd

Is using a short to create a synthetic long shares of stock really legal/allowed/common? If so, seems like a loophole a truck could be driven through that I'd imagine is abused frequently. I've seen synthetic positions like this for options, but never heard about them for stocks.