Context

The optional libgsf dependency is used to create ZIP files as part of the vips_dzsave* operations.

Problem

It appears this dependency is LGPL-2.1-only, which is incompatible with a few upstream dependencies and downstream consumers made available under some other licences, including but not limited to LGPL-3.0-or-later and Apache-2.0.

https://gitlab.gnome.org/GNOME/libgsf/-/issues/28

Examples:

• libheif is made available under LGPL-3.0-or-later, so to meet licensing terms we cannot link against both libgsf and libheif in the same process.
• imagemagick is made available under ImageMagick licence, which a contains patent clause and is incompatible with LGPL-2.1-only, therefore libgsf and libimagemagick cannot be used together in the same process.
• sharp is made available under Apache-2.0 so cannot use libvips compiled with support for libgsf (it has been erroneously doing so, but this will stop).

Possible solutions

• libzip is well-maintained, is made available under BSD-3-Clause and is available on many Linux - https://github.com/nih-at/libzip
• minizip-ng is well-maintained, is made available under Zlib, but isn't readily packaged yet - https://github.com/zlib-ng/minizip-ng