Why not contribute? (to GCC)

[Richard Kenner]

> Nobody can take your code and make it non-free.
> 
> They can take a copy of your code and modify it, but at no time does 
> your original code become non-free. As long as people continue to copy 
> from your "free" version of the code, they can continue to use it for 
> "free".

Correct.  A perhaps better way of putting is "use my code as part of
something that's non-free".