I've recently run into some argument with a person that claims to be a lawyer (I have my suspicions about this not being completely true, though).
As far as I know, copying even one line of code from GPLed program into proprietary body of code requires you to release the whole thing under GPL, if you ever decide to publish the software and make it available to the public.
The person in question claims that it is "absurd" (I know it is, but AFAIK that's how GPL works), it is "redefining the copyright", "GPL has no power to do that", and claiming that "one line of GPLed code makes you release the whole thing under GPL" is absurd. That contradicts the GPL FAQ.
Can somebody clarify the situation? Am I right in assumption that copying even smallest subroutine from GPL program into your code automatically makes your program a "derived work" which means you are obliged to release it under GPL license if you publish it?