default - is_area_protected was renamed from intersects_protection

* backported for working able, renaming compatible function,
  https://github.com/minetest/minetest/pull/7073/files#diff-910f021741edbae068c5577bfc681853791aa6dce900b35305972bf5e24941e5R178
  for engines that already has it enabled, if not just use
  old way function, this backported and enabled
  66372e75d9
  from default game and also from newer engines build-in lua files
* provide both cases based on engine version, newer just call
  the is_area_protected and older just have the code improved,
  with aliasing to the improved code.

mods/default/functions.lua

@@ -1,5 +1,8 @@
 -- mods/default/functions.lua
 
+-- Check for a volume intersecting protection
+local is_50 = minetest.has_feature("object_use_texture_alpha") or nil
+
 --
 -- Sounds
 --
@@ -482,25 +485,32 @@ minetest.register_abm({
 
 
 --
--- Checks if specified volume intersects a protected volume
+-- Checks if specified volume intersects a protected volume, return first node intersected in protected area by player
 --
 
 function default.intersects_protection(minp, maxp, player_name, interval)
 	-- 'interval' is the largest allowed interval for the 3D lattice of checks
-
+	-- but newer engines returned first node that intersect area protected or false
+    if is_50 then
+	return minetest.is_area_protected(minp, maxp, player_name, interval)
+    else
 	-- Compute the optimal float step 'd' for each axis so that all corners and
 	-- borders are checked. 'd' will be smaller or equal to 'interval'.
 	-- Subtracting 1e-4 ensures that the max co-ordinate will be reached by the
 	-- for loop (which might otherwise not be the case due to rounding errors).
 	local d = {}
 	for _, c in pairs({"x", "y", "z"}) do
+
+		if minp[c] > maxp[c] then
+			local tmp = maxp[c]
+			maxp[c] = minp[c]
+			minp[c] = tmp -- Repair positions: 'minp' > 'maxp'
+		end
+
 		if maxp[c] > minp[c] then
 			d[c] = (maxp[c] - minp[c]) / math.ceil((maxp[c] - minp[c]) / interval) - 1e-4
-		elseif maxp[c] == minp[c] then
+		else
 			d[c] = 1 -- Any value larger than 0 to avoid division by zero
-		else -- maxp[c] < minp[c], print error and treat as protection intersected
-			minetest.log("error", "maxp < minp in 'default.intersects_protection()'")
-			return true
 		end
 	end
 
@@ -510,14 +520,23 @@ function default.intersects_protection(minp, maxp, player_name, interval)
 			local y = math.floor(yf + 0.5)
 			for xf = minp.x, maxp.x, d.x do
 				local x = math.floor(xf + 0.5)
-				if minetest.is_protected({x = x, y = y, z = z}, player_name) then
-					return true
+				local pos = {x = x, y = y, z = z}
+				if core.is_protected(pos, player_name) then
+					return pos
 				end
 			end
 		end
 	end
 
 	return false
+
+    end
+
+end
+
+if not is_50 then
+	-- older engines backguar compatibility
+	minetest.is_area_protected = default.intersects_protection
 end