Codefix: early continue, avoid sideeffects

Co-authored-by: Peter Nelson <peter@fuzzle.org>

src/tree_cmd.cpp

@@ -58,6 +58,7 @@ static const uint16_t DEFAULT_TREE_STEPS = 1000;             ///< Default number
 static const uint16_t DEFAULT_RAINFOREST_TREE_STEPS = 15000; ///< Default number of attempts for placing extra trees at rainforest in tropic.
 static const uint16_t EDITOR_TREE_DIV = 5;                   ///< Game editor tree generation divisor factor.
 static const uint16_t FOREST_THRESHOLD = 6;                  ///< Minimum amount of trees required to be considered a forest.
+static const uint16_t FOREST_SEARCH_RADIUS = 2;              ///< Radius of area to examine when determining forest status.
 
 /**
  * Tests if a tile can be converted to MP_TREES
@@ -96,17 +97,13 @@ static bool IsNearbyForest(TileIndex tile)
 	if (IsTileType(tile, MP_TREES)) return true;
 
 	/* Count the trees around the clear tile to determine if it's near a forest */
-	for (int x = -2; x <= 2; x++) {
-		for (int y = -2; y <= 2; y++) {
-			TileIndex vincity = TileAddWrap(tile, x, y);
-			if (vincity != INVALID_TILE &&
-				IsTileType(vincity, MP_TREES)) {
-				planted_tile_count++;
-			}
-		}
+	for (TileIndex t : TileArea(tile).Expand(FOREST_SEARCH_RADIUS)) {
+		if (!IsTileType(t, MP_TREES)) continue;
+		++planted_tile_count;
+		if (planted_tile_count >= FOREST_THRESHOLD) return true;
 	}
 
-	return (planted_tile_count >= FOREST_THRESHOLD);
+	return false;
 }
 
 /**
@@ -802,7 +799,7 @@ static void TileLoop_Trees(TileIndex tile)
 			break;
 
 		case 6: // final stage of tree destruction
-			if (!CanPlantExtraTrees(tile)) {
+			if (!CanPlantExtraTrees(tile) || (_settings_game.game_creation.tree_placer == TP_IMPROVED && !IsNearbyForest(tile))) {
 				/* if trees can't spread just plant a new one to prevent deforestation */
 				SetTreeGrowth(tile, 0);
 			} else if (GetTreeCount(tile) > 1) {
@@ -810,12 +807,6 @@ static void TileLoop_Trees(TileIndex tile)
 				AddTreeCount(tile, -1);
 				SetTreeGrowth(tile, 3);
 			} else {
-				/* Backups the type of tree if using improved trees */
-				TreeType treetype;
-				if (_settings_game.game_creation.tree_placer == TP_IMPROVED && IsTileType(tile, MP_TREES)) {
-					treetype = GetTreeType(tile);
-				}
-
 				/* just one tree, change type into MP_CLEAR */
 				switch (GetTreeGround(tile)) {
 					case TREE_GROUND_SHORE: MakeShore(tile); break;
@@ -837,11 +828,6 @@ static void TileLoop_Trees(TileIndex tile)
 						}
 						break;
 				}
-
-				/* When using improved trees, when a "alone" tree is dead, a new one is planted immediately. */
-				if (_settings_game.game_creation.tree_placer == TP_IMPROVED && !IsNearbyForest(tile)) {
-					PlantTreesOnTile(tile, treetype, 0, 0);
-				}
 			}
 			break;