From c3466124684771b27ed34c0b5e65b57ea30ff795 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Mon, 6 Jan 2025 19:42:11 +0100
Subject: [PATCH] Fix falling nodes digging nodes they aren't supposed to
 (#15638)

---
 builtin/game/falling.lua | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/builtin/game/falling.lua b/builtin/game/falling.lua
index bb6ca1a64..6abd16c58 100644
--- a/builtin/game/falling.lua
+++ b/builtin/game/falling.lua
@@ -308,23 +308,26 @@ core.register_entity(":__builtin:falling_node", {
 
 			core.remove_node(bcp)
 		else
+			-- We are placing on top so check what's there
 			np.y = np.y + 1
-		end
 
-		-- Check what's here
-		local n2 = core.get_node(np)
-		local nd = core.registered_nodes[n2.name]
-		-- If it's not air or liquid, remove node and replace it with
-		-- it's drops
-		if n2.name ~= "air" and (not nd or nd.liquidtype ~= "source") then
-			if nd and nd.buildable_to == false then
+			local n2 = core.get_node(np)
+			local nd = core.registered_nodes[n2.name]
+			if not nd or nd.buildable_to then
+				core.remove_node(np)
+			else
+				-- 'walkable' is used to mean "falling nodes can't replace this"
+				-- here. Normally we would collide with the walkable node itself
+				-- and place our node on top (so `n2.name == "air"`), but we
+				-- re-check this in case we ended up inside a node.
+				if not nd.diggable or nd.walkable then
+					return false
+				end
 				nd.on_dig(np, n2, nil)
 				-- If it's still there, it might be protected
 				if core.get_node(np).name == n2.name then
 					return false
 				end
-			else
-				core.remove_node(np)
 			end
 		end