compiler wont complain about it. actually it is good.
the reason is , In earlier days people dont have modern
IDE, so they used this if statement to commenting out the block of code. it is less error pron compare to block comment(/* */) . since you cant apply nested block comment(/* /* */ */) , compiler will complain about it.
so, if a block of code already contain block comment, they started to put if(false){} around the block of code.
but nowadays modern IDE will do inline comment to a particular lines of statement.