Re: AX_PROG_NASM et al: Would you agree to re-license your macros?

[Peter Simons]

Hi Bogdan,

thank you for the quick response.

 > Could you please provide more details? I'm interested which "definition"
 > does the configure script fall under and what restrictions does it
 > impose.

Please know that I am not a lawyer -- I have no professional expertise in
that area. However, my understanding is that LGPL doesn't coexist with some
other free software licenses. For example, LGPL3 is incompatible with GPL2.
Thus, if a macro is licensed LGPL3, the generated configure script cannot be
distributed under GPL2.

This is a subtle problem, but precisely because of its subtlety the FSF is
worried that our users might end up violating the LGPL license without even
realizing it.

 > Which BSD license is recommended?

We recommend the so-called "revised BSD license". You'll find the complete
text here: http://www.nongnu.org/autoconf-archive/ax_perl_ext_flags.html

 > What does "GPL plus Autoconf Exception" look like?

That license consists of a standard GPL2+ or GPL3+ text with the following
addition:

 | As a special exception, the respective Autoconf Macro's copyright owner
 | gives unlimited permission to copy, distribute and modify the configure
 | scripts that are the output of Autoconf when processing the Macro. You
 | need not follow the terms of the GNU General Public License when using or
 | distributing such scripts, even though portions of the text of the Macro
 | appear in them. The GNU General Public License (GPL) does govern all
 | other use of the material that constitutes the Autoconf Macro.
 |
 | This special exception to the GPL applies to versions of the Autoconf
 | Macro released by the Autoconf Archive. When you make and distribute a
 | modified version of the Autoconf Macro, you may extend this special
 | exception to the GPL to apply to your modified version as well.

A complete example of GPL2+ with Autoconf Exception is here:

  http://www.nongnu.org/autoconf-archive/ax_check_glut.html

GPL3+ with Autoconf Exception looks quite similar, for example:

  http://www.nongnu.org/autoconf-archive/mp_with_curses.html

Take care,
Peter