Version 7.9.0 is available upstream. Please consider updating! It seems that version 7.9.0 is available upstream, while the latest version in the Gentoo tree is 7.7.5. You think this warning is false? Read more about it here.
libpqxx is the official C++ client API for PostgreSQL. If you are writing
software in C++ that needs to access databases managed by Postgres — on just
about any platform — then libpqxx is the library you use. Supersedes the now
defunct libpq++ (AKA, libpqpp) API.