[OKREF]

Just read this on the NFHS site.

3. FREE THROW SHOOTER

Rule 9-1-3g was revised in 2014-15 to allow a player occupying a marked lane space to enter the lane on the release of the ball by the free thrower. As a result of this change, protection of the free thrower needs to be emphasized. On release of the ball by the free thrower, the defender boxing out shall not cross the free-throw line extended into the semicircle until the ball contacts the ring or backboard. A player, other than the free thrower, who does not occupy a marked lane space, may not have either foot beyond the vertical plane of the free-throw line extended and the three-point line which is farther from the basket until the ball touches the ring or backboard or until the free throw ends.

I'm assuming this is a violation and will be treated as if someone entered the lane early. Or if there is contact it could be a foul?