VoxeLibre/mods/PLAYER/vl_pickblock/init.lua

local S = minetest.get_translator("vl_pickblock")

local function pickblock(itemstack, placer, pointed_thing)
	local node = minetest.get_node_or_nil(pointed_thing.under)
	if not node then return end

	local def = minetest.registered_nodes[node.name]
	if not def then return end

	local rnode
	-- if this is an 'illegal' node and there's an explicit `_vl_pickblock` field, then return it
	-- if the node isn't 'illegal', return it as-is
	-- (and if it's 'illegal' and no `_vl_pickblock` is defined, well, bad luck)
	local illegal = (def.groups.not_in_creative_inventory and def.groups.not_in_creative_inventory ~= 0)
	if illegal then
		if def._vl_pickblock then
			rnode = def._vl_pickblock
		end
	else
		rnode = node.name
	end

	-- check if the picked node is already on the hotbar
	-- if so, notify the player
	local inv = placer:get_inventory()
	for i=1,placer:hud_get_hotbar_itemcount() do
		local stack = inv:get_stack("main", i)
		if stack:get_name() == rnode then
			local msg = S("@1 is on slot @2", stack:get_short_description(), minetest.colorize(mcl_colors.YELLOW, i))
			mcl_title.set(placer, "actionbar", {text = msg, stay = 30})
			return
		end
	end

	return rnode
end

minetest.override_item("", {
	on_place = function(itemstack, placer, pointed_thing)
		if mcl_util.call_on_rightclick(itemstack, placer, pointed_thing) then
			return
		elseif minetest.is_creative_enabled(placer:get_player_name()) then
			return pickblock(itemstack, placer, pointed_thing)
		end
	end
})