Improve detection of unbreakable blocks.

init.lua

@@ -439,14 +439,16 @@ doc.new_category("nodes", {
 
 			formstring = formstring .. "\n"
 
-			--[[ Check if there are no groups at all, helps for finding undiggable nodes,
+			-- Mining groups
-			-- but this approach might miss some of these; still better than nothing. ]]
+			if data.def.pointable ~= false and (data.def.liquid_type == "none" or data.def.liquid_type == nil) then
+				-- Check if there are no mining groups at all
 				local nogroups = true
-			for k,v in pairs(data.def.groups) do
+				for groupname,_ in pairs(mininggroups) do
-				-- If this is reached once, we know the groups table is not empty
+					if data.def.groups[groupname] ~= nil or groupname == dig_immediate then
 						nogroups = false
 						break
 					end
+				end
 				-- dig_immediate
 				if data.def.drop ~= "" then
 					if data.def.groups.dig_immediate == 2 then
@@ -490,6 +492,7 @@ doc.new_category("nodes", {
 					end
 					formstring = formstring .. "\n"
 				end
+			end
 
 			-- Custom factoids are inserted here
 			for i=1,#factoid_generators.nodes do