It looks like it is bundling a relatively old version of dev-cpp/yaml-cpp (0.6.3): https://gitlab.com/hepcedar/lhapdf/-/tree/main/src/yamlcpp
I would prefer not to diverge too much from upstream, since that naturally puts more effort on gentoo's side. I'd first try to: - get upstream to add a conf flag for using the system's yaml-cpp - get upstream to update their yaml-cpp
Upstream accepts option to use system's yaml-cpp: https://gitlab.com/hepcedar/lhapdf/-/issues/80#note_2168025870 I'll do that when I find time.