You're receiving this canned (template-based) bug report because I found an annoyance with a package during my tinderbox run.
The package in question is checking for one out of a series of USE flags to be enabled, likely because these are multiple selectable backends, but it currently does not use the EAPI=1 feature of default USE flags to work out of the box.
You can see in my blog post in the URL field why that's a problem, and how to address the issue.
It would be very kind of you for both users and developers working on automated reporting, if the ebuild for the package enabled by default at least one backend (more might be enabled if needed).
Please note that sometimes you don't feel the need for this because the desktop profile already enables some of the USE flags, but please consider the idea of enabling them nonetheless, it would help a lot.
I'm planning to fix this by eventually splitting poppler and -bindings into the following packages (from memory):
But setting a default use flag on the current package probably isn't a good idea since each use flag pulls in a mayor gui library.
Fixed in dev-libs/poppler-glib. You have only [cairo] to toggle there.