Re: [Question]:Question about bison adding GPL copyright to the parser files generated by bison and yacc.c

[Hans Åberg]

> On 26 Jan 2019, at 21:48, Christian Schoenebeck <address@hidden> wrote:
> 
> On Samstag, 26. Januar 2019 14:31:06 CET Hans Åberg wrote:
>>> On 21 Jan 2019, at 17:24, bird bravo <address@hidden> wrote:
>>>  I noticed that when I use bison and the parser skeleton(yacc.c) to
>>> 
>>> generate a parser file... there will be a copyright notice to claim the
>>> file is a GPLV3 and an exception declaration... I wanna know is that OK to
>>> use and distribute the parser file as I wish..
>> 
>> Yes, see [1]. The copyright applies to the skeleton code which is copied
>> over to the generated parser, but there is an exception added for that.
>> 
>> 1. https://www.gnu.org/software/bison/manual/html_node/Conditions.html
> 
> No, that's not what the exception sais. The exception applies (and hence the 
> freedom to distribute a Bison generated parser under any arbitrary, different 
> license than GPL) only if the generated parser is not itself a parser 
> generator. This is not as obvious as you might think. It really depends on 
> what his generated parser is capable to do.

From a legal point of view, copyright applies to the code in the skeleton file, 
as the other part is considered machine generated, like in an editor, and not 
copyrightable.

> I give you a simple example: let's say you used Bison to develop a tool which 
> converts source code from one programming language A to B. Now you might 
> think 
> this is not a parser generator. Well, it was obviously not your intention. 
> But 
> now consider somebody uses that conversion tool for converting a parser  
> originally written in programming language A to language B.
> 
> Right, your Bison generated conversion tool just generated a parser.

A parser generator is not merely a program that generates a parser, but does so 
from a grammar [1]. So the intent of the exception, I think, is that you cannot 
use the skeleton as a part of a program like Bison, but perhaps there is the 
need for some clarification.

1. https://en.wikipedia.org/wiki/Compiler-compiler