int       grid;         // Grid feature of the stair.

    stair_info() : destination(), distance(-1), guessed_pos(true)

    stair_info()
        : position(-1, -1), grid(DNGN_FLOOR), destination(),
          distance(-1), guessed_pos(true)

        position.x = position.y = -1;

    void sync_all_branch_stairs();
    void sync_branch_stairs(const stair_info *si);

#include <set>

#define TC_MINOR_VERSION ((unsigned char) 5)

#define TC_MINOR_VERSION ((unsigned char) 6)

    writeShort(file, grid);

    grid = readShort(file);

    sync_all_branch_stairs();

        // All branch stairs land on the same place on the destination level,
        // update the cache accordingly (but leave guessed_pos = true). This
        // applies for both branch exits (the usual case) and branch entrances.
        if (si->destination.id.branch != id.branch)
            sync_branch_stairs(si);

// If a stair leading out of or into a branch has a known destination, all
// stairs of the same type on this level should have the same destination set
// as guessed_pos == true.
void LevelInfo::sync_all_branch_stairs()
{
    std::set<int> synced;
    for (int i = 0, size = stairs.size(); i < size; ++i)
    {
        const stair_info &si = stairs[i];
        if (si.destination.id.branch != id.branch && si.destination.is_valid()
            && synced.find(si.grid) == synced.end())
        {
            synced.insert( si.grid );
            sync_branch_stairs( &si );
        }
    }
}
void LevelInfo::sync_branch_stairs(const stair_info *si)
{
    for (int i = 0, size = stairs.size(); i < size; ++i)
    {
        stair_info &sother = stairs[i];
        if (si == &sother || !sother.guessed_pos || si->grid != sother.grid
            || sother.destination.is_valid())
        {
            continue;
        }
        sother.destination = si->destination;
    }
}

            si.grid     = grd(si.position);

            unsigned char grid = grd[x + 1][y + 1];
            unsigned char envc = (unsigned char) env.map[x][y];

            int grid = grd[x + 1][y + 1];
            int envc = (unsigned char) env.map[x][y];

        // LevelInfos will also be created for levels in the Abyss and
        // Pandemonium, but they shouldn't be saved because the
        // information in them is useless.