anchor.diff:  	return nil
   end
   
  -local function get_visual_studio_directory()
  +local function get_visual_studio_directory_from_registry()
   	assert(type(vars.LUA_RUNTIME)=="string", "requires vars.LUA_RUNTIME to be set before calling this function.")
   	local major, minor = vars.LUA_RUNTIME:match('VCR%u*(%d+)(%d)$') -- MSVCR<x><y> or VCRUNTIME<x><y>
   	if not major then 
  
positive.code: 	return nil
  end
  
  local function get_windows_sdk_directory()
  	assert(type(vars.LUA_RUNTIME) == "string", "requires vars.LUA_RUNTIME to be set before calling this function.")
  	-- Only v7.1 and v6.1 shipped with compilers
  
negative.code: 		end
  	end
  
  	-- 3. try for Windows SDKs command line tools.
  	local wsdkdir = get_windows_sdk_directory()
  	if wsdkdir then
  		local setenv = wsdkdir.."Bin\\SetEnv.cmd"
  