/**
 * Check whether growing on a half-tile coast tile ends up blocking a water connection
 *
 * @param tile The target tile
 * @return true if building here blocks a water connection
 */
static bool GrowingBlocksWaterConnection(TileIndex tile)
{
	if (!IsValidTile(tile)) return false;

	Slope slope = GetTileSlope(tile);
	/* Is this a coast tile with one corner raised ? */
	if (IsSlopeWithOneCornerRaised(slope) && IsCoastTile(tile)) {
		Corner corner = GetHighestSlopeCorner(slope);
		Corner opposite_corner = OppositeCorner(corner);

		static const Direction corner_to_direction[] = { DIR_W, DIR_S, DIR_E, DIR_N };
		extern const TileIndexDiffC _tileoffs_by_dir[DIR_END];
		TileIndexDiffC diffc = _tileoffs_by_dir[corner_to_direction[opposite_corner]];

		TileIndex opposite_tile = TileAddWrap(tile, diffc.x, diffc.y);
		if (IsValidTile(opposite_tile)) {
			static const struct { TrackBits track_mask_1, track_mask_2, track_mask_1_90_deg, track_mask_2_90_deg; } track_bit_table[] = {
				/*         t1x,t1y,t2x,t2y,              track_mask_1          ,        track_mask_2          track_mask_1_90_deg, track_mask_2_90_deg, opposite_tile */
				/* CORNER_W  0,  1, -1,  0,  */ { TRACK_BIT_X | TRACK_BIT_RIGHT, TRACK_BIT_Y | TRACK_BIT_RIGHT, TRACK_BIT_3WAY_NE, TRACK_BIT_3WAY_SE }, /* -1,  1 */
				/* CORNER_S  1,  0,  0,  1,  */ { TRACK_BIT_Y | TRACK_BIT_UPPER, TRACK_BIT_X | TRACK_BIT_UPPER, TRACK_BIT_3WAY_NW, TRACK_BIT_3WAY_NE }, /*  1,  1 */
				/* CORNER_E  0, -1,  1,  0,  */ { TRACK_BIT_X | TRACK_BIT_LEFT , TRACK_BIT_Y | TRACK_BIT_LEFT , TRACK_BIT_3WAY_SW, TRACK_BIT_3WAY_NW }, /*  1, -1 */
				/* CORNER_N -1,  0,  0, -1,  */ { TRACK_BIT_Y | TRACK_BIT_LOWER, TRACK_BIT_X | TRACK_BIT_LOWER, TRACK_BIT_3WAY_SE, TRACK_BIT_3WAY_SW }, /* -1, -1 */
			};

			TileIndex tile_1 = TileAddWrap(tile, opposite_corner & 1 ? diffc.x : 0, opposite_corner & 1 ? 0 : diffc.y);
			TileIndex tile_2 = TileAddWrap(tile, opposite_corner & 1 ? 0 : diffc.x, opposite_corner & 1 ? diffc.y : 0);

			bool forbid_90_deg = _settings_game.pf.forbid_90_deg;

			TrackBits track_1 = TrackStatusToTrackBits(GetTileTrackStatus(tile_1, TRANSPORT_WATER, 0));
			TrackBits track_2 = TrackStatusToTrackBits(GetTileTrackStatus(tile_2, TRANSPORT_WATER, 0));

			TrackBits next_track_1 = (forbid_90_deg ? track_bit_table[corner].track_mask_1 : track_bit_table[corner].track_mask_1_90_deg) & track_1;
			TrackBits next_track_2 = (forbid_90_deg ? track_bit_table[corner].track_mask_2 : track_bit_table[corner].track_mask_2_90_deg) & track_2;
			TrackBits main_track_1 = (forbid_90_deg ? track_bit_table[opposite_corner].track_mask_2 : track_bit_table[opposite_corner].track_mask_2_90_deg) & track_1;
			TrackBits main_track_2 = (forbid_90_deg ? track_bit_table[opposite_corner].track_mask_1 : track_bit_table[opposite_corner].track_mask_1_90_deg) & track_2;

			/* Is there a connection between tile_1 and tile_2 via tile? */
			if (main_track_1 && main_track_2) {
				TrackBits opposite_track = TrackStatusToTrackBits(GetTileTrackStatus(opposite_tile, TRANSPORT_WATER, 0));
				/* Is there an opposite_track that can be used to try an alternative connection? */
				if (CornerToTrackBits(corner) & opposite_track) {
					TrackBits mirror = TRACK_BIT_CROSS | (corner & 1 ? TRACK_BIT_HORZ : TRACK_BIT_VERT);
					/* Is there a connection between tile_1 and tile_2 via opposite_tile? */
					if (next_track_1 & (main_track_1 ^ mirror) && next_track_2 & (main_track_2 ^ mirror)) {
						/* There is an alternative connection. Town can grow on tile. */
						return false;
					}
				}
				/* There is either no opposite_track, or an incomplete connection via opposite_tile. */
				return true;
			}
		}
	}
	/* There was no connection via tile, or it was incomplete, or the opposite_tile is outside the map. */
	return false;
}