Move setDisplacedBlock() into an interface

Author: ipad54

src/block/Block.php

@@ -418,14 +418,6 @@ public function getDisplacedBlock() : ?Block{
 		return null;
 	}
 
-	/**
-	 * @internal
-	 * Called when block is loaded to update its cover.
-	 */
-	public function setDisplacedBlock(?Block $block) : void{
-		//NOOP
-	}
-
 	/**
 	 * Returns whether this block can be placed when obtained as an item.
 	 */

src/block/utils/BlockDisplacer.php

@@ -0,0 +1,40 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+ */
+
+declare(strict_types=1);
+
+namespace pocketmine\block\utils;
+
+use pocketmine\block\Block;
+
+/**
+ * Indicates that a block can contain another block inside.
+ * Used in things like waterlogging & snowlogging.
+ */
+interface BlockDisplacer{
+
+	/**
+	 * @internal
+	 * Called when a block is loaded to update its contained block.
+	 * Do NOT use this in plugins, use your block provided API instead.
+	 */
+	public function setDisplacedBlock(?Block $block) : void;
+}

src/block/utils/CoveredByWater.php

@@ -26,7 +26,7 @@
 use pocketmine\block\Block;
 use pocketmine\block\Water;
 
-interface CoveredByWater{
+interface CoveredByWater extends BlockDisplacer{
 
 	public function getWaterCover() : ?Water;
 

src/world/World.php

@@ -34,6 +34,7 @@
 use pocketmine\block\tile\Tile;
 use pocketmine\block\tile\TileFactory;
 use pocketmine\block\UnknownBlock;
+use pocketmine\block\utils\BlockDisplacer;
 use pocketmine\block\VanillaBlocks;
 use pocketmine\data\bedrock\BiomeIds;
 use pocketmine\data\bedrock\block\BlockStateData;
@@ -2036,7 +2037,9 @@ public function getBlockAt(int $x, int $y, int $z, bool $cached = true, bool $ad
 			$displacedBlock = null;
 		}
 
-		$block->setDisplacedBlock($displacedBlock);
+		if($block instanceof BlockDisplacer){
+			$block->setDisplacedBlock($displacedBlock);
+		}
 		$block->position($this, $x, $y, $z);
 
 		if($this->inDynamicStateRecalculation){