As a patch or addition, your source code is likely to be considered a derivative work, regardless of whether you actually build it into a binary.

As other people already said, intellectual property laws restrict not only the work itself, but also derivative works.

A patch is a derivative work, no matter how you try to dodge that part of the law. So it would still be violation of copyright.

To be clear, the silly question I posed was not directed at avoiding copyright violations. What I ask is whether anyone is ever curious about the value of the derivative work versus the original work.

For example, the original work might be very valuable, a significant work. It could be the collective work of many authors. But it has been made available for free. The derivative work, maybe patches or some additional source code by a single author, is also valuable but on its own much less so.

Then the large original work is packaged together with the patches and additonal source code as a "derivative work". It is commercially licensed to an end user who sees the value as a whole, most of it coming from the original work, which of course was available for free.

Depending on whether attribution is given, the user may have no idea that the core of the product was open source and available for free.

More importantly, there appears to be no assessment of the relative "value" of the free portion versus the closed-source commercial portion of the product.

I'm not entirely sure that's correct. If you try to sell something that relies on GPL software, it's considered a derivative work even if you don't distribute the GPL software with yours.

It is a derivative work, but selling derivatives of GPL-ed software is entirely legal and not forbidden by the GPL. Distributing binaries (regardless if for free or not) of GPL-derived software without distributing the source from which the binaries were derived (or without offering a reasonable way of getting the source on demand) is forbidden by the GPL. Moreover, the source of the derivative work must be offered under the GPL.

(Edited to add the last statement above, for clarity.)

While that is true, as part of a derivative work, your users would have your source under GPL terms.

Absolutely you can sell, but your can't restrict user rights

This is correct - you not only must include the source code for your binary, you also must include it under the same terms as the original source code.

So if someone just happens to distribute the source code for Hancom Office before this is resolved in the courts, would he or she be in the free and clear?

A license can't affect the copyright of any other code. So Hancom is just in violation of the GPL and has lost its right to use Ghostscript; it's not automatically GPL'd.

This is correct. Without a license, Hancom is liable for copyright infringement of the Artifex code if it continues distributing its product. It will be forced to either buy a license or reform its product to use an alternative, but it won't be forced to release its source code.

Probably not. It's unlikely either party will want this to go to trial so it'll probably end in a settlement where the company buys a license on top of damages.

Agreed, I didn't mean to imply otherwise.