for (Rank rank = RANK_8; rank >= RANK_1; --rank)
{
for (File file = FILE_A; file <= FILE_H; ++file)
- s.append(b & (file | rank) ? "| X " : "| ");
+ s.append(b & make_square(file, rank) ? "| X " : "| ");
s.append("|\n+---+---+---+---+---+---+---+---+\n");
}