void SetTargetFramework(string fx)
{
TargetFramework tf;
if (!TargetFramework.TryParse(fx, out tf))
{
throw ErrorHelper.CreateError(68, fx);
}
target_framework = tf;
if (!TargetFramework.IsValidFramework(target_framework.Value))
{
throw ErrorHelper.CreateError(70, target_framework.Value, string.Join(" ", TargetFramework.ValidFrameworks.Select((v) => v.ToString()).ToArray()));
}
}