Re: GNU bison++ and flex

"Mike Dimmick" <>
22 May 2001 13:34:45 -0400

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Related articles
Re: GNU bison++ and flex (Mike Dimmick) (2001-05-18)
Re: GNU bison++ and flex (Zack Weinberg) (2001-05-21)
Re: GNU bison++ and flex (Mike Dimmick) (2001-05-22)
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From: "Mike Dimmick" <>
Newsgroups: comp.compilers
Followup-To: poster
Date: 22 May 2001 13:34:45 -0400
Organization: Compilers Central
References: <> 01-05-048 01-05-051
Keywords: legal
Posted-Date: 22 May 2001 13:34:45 EDT

> >> I am interested in using GNU bison++ 1.21-8 and the flex program provided
> >> with Unix on a Sun Solaris Unix 5.8 box.
> [...]
> >> I have read the GPL License that apply to bison++ 1.21-8 and though
> >> it was hard going I think I understand that I would not be infringing
> >> the license by including the parser generated using bison++ 1.21-8
> >> and the flex provided on the sun box with other software and making
> >> the combination available commercially for a price.
> >
> >If I remember correctly, bison is released under the Limited (or
> >Library) General Public License. This differs from the full General
> >Public License in that you are permitted to LINK TO (but not modify)
> >pieces of the supplied source code. This is necessary for a Bison
> >parser because the parsing automaton is covered by this license and is
> >included in every generated parser (indeed, the portion you wrote, the
> >grammar production rules, are translated merely to state transition
> >and action tables).
> This is a common misconception.

Read the statement at It explains the
reason the terms were changed. I apologise for the fact that I was mistaken
regarding the exact license under which bison is made available - I based
this on my memory of that page, which has turned out to be incorrect.


> [quote from the skeleton file bison.simple from Bison 1.28. The other
> skeleton file, bison.hairy, has no license terms at all; however, to
> the best of my knowledge, it is never used.]

It's used if you construct a 'semantic parser', but no documentation exists
for what this is or why it might be necessary. The online manual is of
course out of date (referring to bison 1.25) and is incomplete, not listing
the option which constructs a semantic parser. I don't currently have a
built executable.

Now to the meat of the issue.

> I'm not familiar with bison++ but I would expect it has the same
> license exception for its skeleton file, or if not, that one would
> be swiftly added if you brought the lack to the attention of the
> authors.

The skeleton files are and bison.h, neither of which carries the
additional disclaimer, bison++ having branched from bison at around version
1.04, so far as I can see. The author's email address is in the bison++ man

> >[1] As you can tell, I'm not keen on the GPL. Make your software
> >freely available if you like, but don't presume to tell me what I can
> >do with _my_ adaptations of the software you have made available. I
> >won't even examine source code of GPL'd software to avoid any possible
> >charge of non-literal copying (writing a new piece of software based
> >on knowledge of another).
> It's unfortunate that this leads you to spread misconceptions.

I don't think I was, particularly; I will admit that the paragraph I wrote
was a little heavy (although you do not mention the exact portion you
consider to be a misconception). What I wrote has exactly the same meaning
as the section of the manual I referenced earlier.

I think any further discussion on the GPL should be performed by email.

[I definitely agree with the last sentence. -John]

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