Kant's philosophy was criticized on exactly these grounds, i.e. that by his system, when the authorities come to your door to look for a friend you're harboring, you should turn him in. I briefly scanned for clever Kant references (e.g. "introduce the brownshirts to your strangely-named cat, Egorial Imperative") but found none. Kant clarified that he did not think it immoral to lie to authorities looking to execute your friend.

The critic was Benjamin Constant. He wrote:

The moral principle stating that it is a duty to tell the truth would make any society impossible if that principle were taken singly and unconditionally. We have proof of this in the very direct consequences which a German philosopher has drawn from this principle. This philosopher goes as far as to assert that it would be a crime to tell a lie to a murderer who asked whether our friend who is being pursued by the murderer had taken refuge in our house.

For Kant's reply, see his essay On a Supposed Right to Lie Because of Philanthropic Concerns.