Re: GNU bison++ and flex

Zack Weinberg <>
21 May 2001 02:01:29 -0400

          From comp.compilers

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)
| List of all articles for this month |

From: Zack Weinberg <>
Newsgroups: comp.compilers
Date: 21 May 2001 02:01:29 -0400
Organization: Ha ha ha.
References: <> 01-05-048
Keywords: GCC
Posted-Date: 21 May 2001 02:01:29 EDT

Mike Dimmick <> writes:
>"Raymond Sebuwufu" <> wrote in message
>> Hi,
>> 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.

Bison itself uses the normal GPL. However, the parsing automaton
has a special license: the GPL plus

/* As a special exception, when this file is copied by Bison into a
      Bison output file, you may use that output file without restriction.
      This special exception was added by the Free Software Foundation
      in version 1.24 of Bison. */

[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.]

"Without restriction" means just what it says; you can do whatever you
like with that output file, including using it in your commercial product.

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.

If you are still uncomfortable, byacc uses the BSD license. It, of course,
generates C, not C++.

>[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.

Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.