If you are thinking about distributing your PostgreSQL extension modules, setting up a portable build system for them can be fairly difficult. Therefore the PostgreSQL installation provides a build infrastructure for extensions, called PGXS (Section 36.19).

When PostgreSQL is built with Meson, it also installs a pkg-config file, postgresql-20-extension.pc (Section 36.20). This file collects the compilation flags needed to build server code, so that extensions built with Meson can compile against the server.