Subject: dumb GPL question
From: "Stephen J. Turnbull" <turnbull@sk.tsukuba.ac.jp>
Date: Wed, 6 Jun 2001 15:50:50 +0900

>>>>> "Bernard" == Bernard Lang <Bernard.Lang@inria.fr> writes:

    Bernard> is it OK to link GPL code to preexisting non-GPL code
    Bernard> (for example a library) ?

Yes, for personal use.  No, if the license of the code prevents
redistributing the library under the GPL.  (There are exceptions for
system software, namely libc, libX11, and libXm (Motif).  All others
please ask rms@gnu.org.)  Cf. Aladdin Ghostscript and libreadline.

It is legal to redistribute a binary compiled from GPL code and linked
to some kinds of non-GPL free software, eg, public domain and X
licenses, as long as the source for the library can be redistributed
under the GPL.  (Hm.  Another dumb question.  Does the GPL require that

#include <gnome.h>

main () { gnome_printf("Hello, world"); }

include all source to GNOME and GTK+ in its distribution?  You're not
allowed to use 3c to escape.)

    Bernard> else, how can one write GPL code in a non-GPL language ?
    Bernard> (i.e. a language with no GPL implementation, especially
    Bernard> of the run-time library, even though it may be
    Bernard> open-source)

This should escape under the "system library" rule in some cases if
the compiler (a) is distributed as a standard part of the operating
system and (b) its runtime library only provides the API to "the
usual" system functions.  Ask RMS.

Otherwise, it's arguable that you cannot.  RMS forced Aladdin to
remove all code and support (eg, Makefile rules) for building Aladdin
Ghostscript with libreadline, because the latter is GPL.  The argument
was that the shim code and Make rules were simply a way to avoid the
intent of the GPL, and thus making the end-user an agent of Aladdin.
So the same argument might apply to writing a program in a language
that requires linking with a non-GPL runtime library, and distributing
as source code.

The whole point of the GPL is to provide incentives for (a) the vendor
of the non-GPL software to rerelease under GPL or (b) third-parties to
reimplement and release under GPL.


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