It’s a neat trick, but calling it a “leading zero” seems like a bit of a stretch to me. It’s the left operand of a subtraction expression; omitting the spaces around the operator doesn’t make it a single token. (See also the --> “operator” trick.)
Somebody decided to take the time to write a blog post about adding a useless 0 in front of an expression to work around and silence a useless compiler warning. Epic use of multiple developers’ time.