Clone a function and its upvalues

gistfile1.lua

local function clone_function(fn)
  local dumped = string.dump(fn)
  local cloned = loadstring(dumped)
  local i = 1
  while true do
    local name, val = debug.getupvalue(fn, i)
    if not name then
      break
    end
    debug.setupvalue(cloned, i, val)
    i = i + 1
  end
  return cloned
end


local x = "hello"
local function fn()
  return "x: " .. x
end

local fn2 = clone_function(fn)

print(fn())
print(fn2())