[Interest] Is it a LGPLv3 infringement to copy paste qFuzzyCompare implementation

André Somers andre at familiesomers.nl
Fri Jul 22 11:49:54 CEST 2016

Op 22/07/2016 om 11:41 schreef Ch'Gans:
> On 22 July 2016 at 20:25, Jean-Michaël Celerier
> <jeanmichael.celerier at gmail.com> wrote:
>>> I was pointed out that there's a potential LGPLv3 license
>> infringement, although I understand where the FUD is coming from, I
>> think that it is OK to read LGPLv3 source code to get inspired as long
>> as you don't blindly copy/paste code (In my case i checked out quite a
>> few articles and forum threads before choosing the Qt way as the best
>> way to do it for my application).
>> There is no infrigement, you can even use directly qFuzzyCompare in your
>> proprietary code :
>>  From the LGPLv3.0
>> The object code form of an Application may incorporate material from a
>> header file that is part of the Library. You may convey such object code
>> under terms of your choice, provided that, if the incorporated material is
>> not limited to numerical parameters, data structure layouts and accessors,
>> or small macros, inline functions and templates (ten or fewer lines in
>> length), you do both of the following:
>> a) Give prominent notice with each copy of the object code that the Library
>> is used in it and that the Library and its use are covered by this License.
>> b) Accompany the object code with a copy of the GNU GPL and this license
>> document.
> Interesting excerpt indeed. So you can use small inlines and templates
> of a LGPLv3 header file "under terms of your choice"! What a surprise!
> This is quite liberal for a so-called "viral" license.
> I'm using "viral" here because this is quite often the term used to
> spread FUD, I have personally always liked GNU licenses and have great
> respect toward all the people behind them.
> Thanks a lot for pointing that out.
Please be careful there. It is about *object code*, not source code! The 
idea of this section is to deal with the reality of compilers and 
linkers: stuff from headers ends up in your own object files. So, the 
license allows that to happen. It is *not* a licence to copy sources 
into your own sources and compiling that.

And yes: studying source code from GPL like-licenced projects is 
explicitly encouraged.


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