The GPL does not have that restriction. GPL software can be distributed alongside non-GPL-compliant software just fine. This happens in every single Linux distribution.

> The license must not place restrictions on other software that is distributed along with the licensed software.

When I base software on GPL software, then my software is distributed along with that GPL software. According to this phrase, GPL might not place restrictions on my software. Yet it does.

There is a profound misunderstanding here somewhere. I suspect it is coming from the use of the phrase 'base on'. If you modify GPL licensed software, your software is restricted because it qualifies as a derivative work under copyright law, and it must comply with GPL. But if you zip up a GPL program with your non-GPL program and distribute the bundle, the GPL does nothing to restrict your non-GPL program. If there's linking involved, it gets more complicated, but that's unrelated to this discussion.

> If there's linking involved, it gets more complicated, but that's unrelated to this discussion.

I think it is very much related. If my linker cannot link GPLed software because of the license of this software, then this software is restricting my linker. As per the definition of opensource.org, GPLed software is not open source.

Again,

> 9. License Must Not Restrict Other Software

Other software (distributed alongside, "mere aggregation") != Software based on a work (derivative).

GPL obligations apply in the latter case, OSI definition talks about the first case.

If your view of the definition were true, then the OSI definition would have been more clear about the distinction.

Further, as an example, software running on Linux is clearly different than the Linux kernel. Nobody would say that an application and the OS kernel is the same software. OSI doesn't make a distinction between library calls and kernel calls.

OSI specifically lists the GPL as an open source approved license.

https://opensource.org/licenses/GPL-2.0 https://opensource.org/licenses/GPL-3.0

Even AGPL is approved. https://opensource.org/licenses/AGPL-3.0

The GPL doesn't place such restrictions.

People might wonder why. Since these statements sound incompatible.

The GPL requires two things, mainly, if you're going to use something GPL in a closed source package.

1) Attribution. You can't just take and not comment.

2) Modifications should be made available under the same license.

this means that if you're using GPL software and including it as a shared object, then you're fine.

If you need to modify that software to make it work for you (including fixing bugs) then you need to make those elements available.

This is different than insisting that anything that touches GPL code be GPL also.

Some proprietary licenses do have provisions for this, which makes them GPL incompatible.

This seems very misleading. A library released under the GPL cannot be used by non-GPL software. That's by design. It's the reason for the more permissive LGPL licence.

edit For brevity I ignored dual licensing. If you release your library under both GPL and Apache, then things are of course different.

https://www.gnu.org/licenses/why-not-lgpl.en.html

I thought that was the LGPL, but the GPL requires anything using it (as an include, not a standalone binary) to be GPL as well.