If you accidentally write "return x = 1" when x is a variable, you always return true. If you return "1 = x", you cause a syntax error. So some people have gott

If you accidentally write "return x = 1" when x is a variable, you always return true. If you return "1 = x", you cause a syntax error. So some people have gotten into the habit of writing constants on the left, even if the return value of __builtin_popcount is not assignable.