Here is reply from CUPS mailing list:
On 11/08/2017 08:58 PM, Michael Sweet wrote:
Zdenek,
On Nov 8, 2017, at 11:11 AM, Zdenek Dohnal zdohnal@redhat.com wrote: ... would you mind considering dual license - Apache License 2.0 and GPLv2+? Because "OS-supplied library" definition is relative and it could end up that any widely used library can be exception (not mention widely used libraries differs across distributions - so library would be count as "OS-supplied library" on one distro and not on a other) - and that will lead into nullifying existing licensing rules.
IANAL and am not comfortable getting into a legal debate about what constitutes an OS-supplied library or whether GPL2-only software can "legally" link against libcups. But as an example, CUPS had to deal with this when linking against OpenSSL in the past by adding an exception to the license file saying "it is OK to link CUPS against OpenSSL"... I don't see why that approach would not work for any GPLv2-only project, if there was any question about CUPS being a standard OS library after almost 20 years of use...
Anyways, I can certainly forward your dual-licensing request to the appropriate people at Apple, but I'm sure they will want to know which projects/applications you think will be unable to continue using CUPS, and why.
Thanks!
Michael Sweet, Senior Printing System Engineer
cups-devel mailing list cups-devel@cups.org https://lists.cups.org/mailman/listinfo/cups-devel
AFAIK such projects are gutenprint, cups-filters or hplip... does anyone have in mind other projects, which will be unable to use CUPS and reason?