Re: Bug#189164: libdbd-mysql-perl uses GPL lib, may be used by GPL-incompatible apps

[Edmund GRIMLEY EVANS <edmundo@rano.org>]

Anthony DeRobertis <asd@suespammers.org>:

> Given:
> 	1) Library GPLLib is under the GPL
> 	2) Perl module Iface provides an interface to various implementations
> 	   of similar features, and the user selects which implementation to
>         use
> 	3) Perl modules PM uses GPLLib to implement Iface
> 	4) Perl program P is under a GPL-incompatible license
> 
> Question:
>     Is is permissible for P to use PM through Iface?

Yes, of course, because the GPL doesn't restrict use!

> I argue "yes" because I don't see how P could _possibly_ be held to be 
> a derived worked of GPLLib, and thus is not subject to the GPLs 
> restrictions.

P is not a derived work of GPLLib, but P+GPLLib is likely to be a
derived work of GPLLib, in which case it is not allowed to distribute
them together. However, you could certainly distribute P on its own if
you could reasonably claim that P is useful without GPLLib.

> I further argue that if the answer is "no", there is no good reason to 
> say changing the language from perl to shell script should matter, and 
> thus no GPL-incompatibly licensed program can use GNU grep, ls, etc.

There are other implementations of grep, ls, etc, so it would
certainly be all right to distribute the GPL-incompatible shell script
on its own. Debian would distribute the shell script with GNU grep,
ls, etc, so you'd have to find another argument why the script is a
separate work from grep, ls, etc, which is probably doable if the
script makes relatively minor use of grep, etc to do something
independently interesting, but would be a bit harder if the script
implements a graphical interface to grep.

That's how I see it, anyway.

Edmund