I'll post my response to the copy-left discussion here, since comments to comments aren't well defined by the pump standard. It is my understanding of the history of the fabled printer driver, that the existence of the printer driver as proprietary merely annoyed RMS but that he was content to let his driver be public domain (which last time I checked was a permissive type of licensing). Copy-left came about because the printer company then took his code, and incorporated it into their own driver and kept the resulting work as proprietary. Which, of course, greatly offended RMS and created for the FSF and the free software movement, a moral/ethical issue requiring restrictions on licensing so that code could be assured to remain free and couldn't disappear into proprietary black-holes where improvements and derivative works can be made to/on code but not contributed back, locking people into proprietary silos for thing x. As far as LLVM is concerned, I think the fear isn't that these companies will stop contributing code, but that they will stop making their contributions available so that if you want the best compiler for y, you need to use the vendors version