const bool seen = see_grid(c);
    const int grid = ((seen || ignore_terrain_knowledge) ? grd(c)
                                                         : get_envmap_obj(c));

    // [dshaligram] At this point we're guaranteed to know the terrain (see
    // check ^^^), which means we know what dungeon feature is here. Thus it's
    // safe to use the actual dungeon feature directly.
    const dungeon_feature_type grid = grd(c);
    // Also make note of what's displayed on the level map for
    // plant/fungus checks.
    const int levelmap_object = get_envmap_obj(c);

    // FIXME: this compares to the *real* monster at the square,
    // even if the one we've seen is different.

    // Travel will not voluntarily cross squares blocked by immobile monsters.

        && (seen || grid > DNGN_START_OF_MONSTERS)
        && _is_monster_blocked(c))

        && levelmap_object >= DNGN_START_OF_MONSTERS
        && _is_monster_blocked(c)
        // _is_monster_blocked can only return true if monster_at(c) != NULL
        && monster_at(c)->type == levelmap_object - DNGN_START_OF_MONSTERS)

    if (ignore_hostile
        && (seen || grid < NUM_REAL_FEATURES)
        && _is_reseedable(c))

    if (ignore_hostile && _is_reseedable(c))

    if (grid >= NUM_REAL_FEATURES)
        return (true);