// add all X-ray attacks by the rook or queen. Otherwise consider only
// the squares in the pawn's path attacked or occupied by the enemy.
if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
// add all X-ray attacks by the rook or queen. Otherwise consider only
// the squares in the pawn's path attacked or occupied by the enemy.
if ( (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))