🚀 go-pugleaf

%% Regarding Legalities of redistributing bison and GNU make?;
%% flaster@panix.com (Michael Flaster) writes:

    mf> I'm interested in developing some software which I do not
    mf> wish to put under the GPL.  I have 2 questions:

    mf> 1.  If I wish to distribute my source code, and I want to
    mf> distribute some makefiles which work under gmake but not make,
    mf> is that legal?

Of course.  Just as releasing proprietary products that will only
compile with GCC.

    mf> Can I also include a distribution of GNU make?

Of course again: as you mention you must make available the complete
sources but you can certainly include them and a binary... that's the
whole point of the GPL actually :)

    mf> 2.  bison and flex:  Am I allowed to release an executable
    mf> that was generated from bison and flex?  I seem to recall
    mf> that an executable generated by gcc could be released under
    mf> any license, and so I imagine the same would be true of an
    mf> executable generated from bison and flex, but once again,
    mf> I'm not at all sure.  I imagine that the question as to
    mf> whether I could release the source grammars with executables
    mf> for bison and flex would be answered the same way that #1 would
    mf> be...

You might imagine so, but you'd be wrong :-/

First, flex: flex isn't actually under the GPL and so it doesn't apply
to lexers generated with flex.  If you examine the licensing it's much
less restrictive in this way than the GPL, it's closer to Larry Wall's
Artistic License or the BSD license.  So, in short, lexers generated
with flex won't cause you any problems (unless it's been changed since I
used it last).

Second, bison: although you might think bison would use the same rules
as GCC, there's one important difference: when you run your grammar
through bison you get some big data tables; these aren't encumbered via
the GPL of course, just like the .o's generated by GCC aren't
encumbered.

*However*, in order to make sense of those big tables, a large
boilerplate chunk of code (check out the files bison.simple and
bison.hairy) must be included.  That big boilerplate chunk is included
verbatim and is covered under the GPL.  The FSF has held that
incorporating that chunk *does* mean that your program falls under the
GPL.

So, you have a few choices: write a new parser that works with the Bison
data tables so you don't need bison.simple or bison.hairy, punt Bison
and go back to byacc (Berkeley yacc) which is free and unencumbered
except by the BSD license which is pretty simple to satisfy, or punt
both Bison and Flex and go with a better compiler toolkit.

I personally suggest the latter, and my advice is to go straight to
ftp.parr-research.com:/pub/pccts and grab the latest version of PCCTS.

It's completely unencumbered, and it's a *much* improved compiler building
technology, allowing LL(k) parsers, integrating the lexer and parser
into one description file, providing an Enhanced BNF syntax for
describing grammars, improved error handling, many fancy features like
predicate hoisting are allowed, you can pass arbitrary arguments both to
and from BNF rules, etc. etc. etc.

                                                                paul
 _____________________________________________________________________________
/                                                                             \
 Paul D. Smith                   | There's a fine line between fishing, and
 <psmith@wellfleet.com>          | standing on the shore like an idiot.
 Bay Networks, Inc.              | 
 Network Management Development  |                            -- Steven Wright
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