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Comment by phkahler | Hacker News Reader

Isn't LGPL 2.1 is an odd license for something like this? Does it produce a library?

> Does it produce a library?

It is a library.

A _header-only_ library. Not sure how LGPL works for those - not much to avoid linking against... Throw it in your own .dll / .so and use that in your closed-source projects? Standard disclosure: IANAL.

Uh, no, it's not. The shaders are clearly part of the work, so you need to make sure that the shaders are "dynamically linked"; i.e. can be replaced by the end user with their own version in order to comply with the terms of the LGPL.

Paragraph 5 of the LGPL version 2.1 states:

A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.

I am confused with that paragraph. So if I statically compiled a project with Qt without any modification, does it fall outside the scope of LGPL as well?

IIRC it’s unclear if static linking LGPL is okay, so most people steer clear

Static linking is okay and is allowed as a derivative work, but you need to ship object files.

https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDyn...

>(1) If you statically link against an LGPLed library, you must also provide your application in an object (not necessarily source) format, so that a user has the opportunity to modify the library and relink the application.

This is covered in sections 6 and 6a of the LGPL 2.1.

Hello, I am the author of VkFFT. When I made VkFFT I wanted license to be like this: your project doesn't have to be open-source, but please share your modifications to VkFFT. I think about switching it to MPL 2.0, is this one better for everybody?

Goal of LGPL is to protect freedom of developers to modify code of a library (e.g. to improve it, fix bugs, fix incompatibilities, port to new hardware, etc.) shipped as part of proprietary application. This freedom is important for developers of niche OS'es. This protection works, because of hard consequences for proprietary code in case of license violation: proprietary code must be released under GPL then.

MPL doesn't protect such developers, but it "forces" contribution of changes back to original code. In reality, it's ignored.

Header-only library cannot be compiled as separate library, so requirements of LGPL cannot be met by proprietary code.

That would probably do what you want because it applies on a per-file basis and not to the entire program, but make sure you read the MPL FAQ and the fine print before making such a change: https://www.mozilla.org/en-US/MPL/2.0/FAQ/

Yes, MPLv2 does what you want. Consider that it's also used by Eigen. I strongly advocate for MPLv2 for math style libraries.

It might be better to simply switch to the LGPL v3 or later, since that explicitly addresses header libs.

So then the OP is a LGPL header-only library, which is always statically compiled in every source. Do we need to do the same thing, and if yes, how we provide an application to allow recompiling?

If you can't use the object files to rebuild another version of the program with a modifier version of the library then no that probably wouldn't be compliant. In that case you would probably have to modify the library so it's not inlining every function. (Disclaimer: IANAL)

The program seems like it would contain inlined code from the header though right?

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