Re: [License]Is Bison exception only valid on Bison 2.2?

[Christian Schoenebeck]

On Sonntag, 25. Juli 2021 18:01:50 CEST Akim Demaille wrote:
> Hi Kuohong,
> 
> > Le 17 juil. 2021 à 07:33, Kuo-Hong Wang <kuohong@gmail.com> a écrit :
> > 
> > Dear all,
> > Bison is a useful tool!
> 
> Thanks!
> 
> > I have one question about the license of generated files by Bison.
> > 
> > It shows GPL exception with bison as following.  Is the exception only
> > valid on Bison 2.2? or still valid on later versions?
> 
> It was installed in Bison 2.2, and applies to all the versions since
> 2.2.
> 
> > "This special exception was added by the Free Software Foundation in
> > version 2.2 of Bison."
> > 
> > Is it possible to modify bison utility to make that statement more
> > clear(2.2 and after) ?
> 
> I never thought it was unclear :(  And don't feel confortable changing
> this wording.

I don't see any issue in this particular sentence either. It is really just a 
note that this exception was added with version 2.2 of Bison. It does by no 
means define an upper version limit in which the exception would no longer 
apply.

The only issue I personally saw was that Bison's skeleton exception would not 
apply if the Bison generated software would satisfy the purpose or definition 
of a "parser generator" in any way. E.g. Bison generated meta compilers used 
inside build chains would already fall into this category:

https://lists.gnu.org/archive/html/help-bison/2019-01/msg00013.html

I mean it is probably just a theoretical issue. The intention of that 
definition was presumably not prohibiting commercial meta compilers, but in 
the end it would be a gray zone to be considered as part of your 
responsibility.

Best regards,
Christian Schoenebeck