static char base_grid_type( char grid )

static dungeon_feature_type base_grid_type( dungeon_feature_type grid )

    if (grid == DNGN_SECRET_DOOR)

    if (grid_is_wall(grid))

        const int targ_grid = base_grid_type( grd[ targ_x ][ targ_y ] );

        const dungeon_feature_type targ_grid =
            base_grid_type( grd[ targ_x ][ targ_y ] );

    unsigned char       grid;
    char                dx;
    char                dy;

    dungeon_feature_type grid;
    int dx;
    int dy;