See summary. The line root@/usr/lib64 ln -s libstfl.so libstfl.so.0 solves this issue. Even if it is not a gentoo problem (see https://www.mail-archive.com/gentoo-user@lists.gentoo.org/msg180644.html and the corresponding thread), maybe add a patch or something so that the ebuild installs working software ?
There is already a patch for this, and it "should" be working fine. There was bug #719452 bit over two months ago that caused the patch to fail to apply but that's been fixed as well. I verified with dev-libs/stfl-0.24-r2 and libstfl.so.0 is there. Please re-verify, and if still missing provide stfl's build.log and emerge --info output.
Upon closer look, stfl-0.24 (no -r2) has the bug I mentioned above, is this the one you have installed? Try to update if so.
Oh I see what happened, I thought the above bug hadn't hit stable, but changes were made directly in stable, and then it was fixed and took a while to be stabilized. But it is stable now, so I guess this can be considered fixed.
Exactly, r2 version was not stable on my system. It is now and everything is fine. Thanks.