When PostgreSQL is built with Meson, it installs a pkg-config file named postgresql-20-extension.pc. It provides the same compilation flags that are used to build the server itself, so that extensions can be built with Meson against a given PostgreSQL installation. It is also used internally to emit LLVM JIT bitcode for the server and for selected contrib modules.

The file is versioned by major release, so an extension can build against a specific PostgreSQL major version. It offers a Meson-based alternative to PGXS (Section 36.19), which uses make.

To use the postgresql-20-extension.pc infrastructure for your extension, you must write a simple meson.build file. In the meson.build file, you need to include the postgresql-20-extension.pc pkg-config file. Here is an example that builds an extension module named isbn_issn, consisting of a shared library containing some C code, an extension control file, an SQL script, an include file (only needed if other modules might need to access the extension functions without going via SQL), and a documentation text file:

project('isbn_issn', 'c')

pg_ext = dependency('postgresql-20-extension-warnings')

isbn_issn_sources = files('isbn_issn.c')

isbn_issn = shared_module('isbn_issn',
  isbn_issn_sources,
  dependencies: pg_ext,
  install_dir: pg_ext.get_variable(pkgconfig: 'dir_mod'),
)

install_data(
     'isbn_issn.control',
     'isbn_issn--1.0.sql',
     install_dir: pg_ext.get_variable(pkgconfig: 'dir_data'),
)

install_headers(
     'isbn_issn.h',
     install_dir: pg_ext.get_variable(pkgconfig: 'dir_include'),
)

install_data(
     'README.isbn_issn',
     install_dir: pg_ext.get_variable(pkgconfig: 'dir_doc'),
)