Subject: Re: dumb GPL question
From: Ian Lance Taylor <ian@airs.com>
Date: 05 Jun 2001 13:00:51 -0700

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

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

Sure, provided
1) you don't distribute the resulting executable, or
2) source code for the library is available, or
3) the library is normally distributed with the major components of the OS

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

The GPL is compatible with various other free licenses; see
    http://www.gnu.org/philosophy/license-list.html#GPLCompatibleLicenses

> How can one force users of free code to acknowledge the original
> authors in a specific way ?
>   - not possible with GPL
>   - not with LGPL
>   - but LGPL can be modified in this respect with no significant other effect
>   - and of course any free-style open-source licence can do it.

I believe this is essentially correct--you can add an acknowledgement
requirement to any license which doesn't already have it.  You can
easily modify the GPL to force acknowledgement, by adding a condition
to section 2.  The result would no longer be the GPL, and it would not
be GPL compatible.

Cases where people refuse to acknowlege the source of code are few and
far between.  I don't know what the particular concerns are here.

Ian