It's not "inside" the default, as such. I'm not a C expert but, near as I can tell, the labels for a switch statement don't need to occur all be at the same lev

It's not "inside" the default, as such. I'm not a C expert but, near as I can tell, the labels for a switch statement don't need to occur all be at the same level within the control flow inside the switch body. See my other post here about Duff's Device as another neat example of exploiting this.