switch to pkg-config to find out the information about libpq

[darix]

pg_config was meant for building server extensions.

[dvarrazzo]

Patch?

[dvarrazzo]

AFAICS pkg-config only deals with the system package. On my ubuntu laptop I have PG 11 installed but libpq.pg declares to be PG 12 (it belongs to the libpq-dev package). I don't think this can be used.

[darix]

this is not true. pkg-config support is there since pg 8 or so. in doubt you need to set PKG_CONFIG_PATH to find the .pc files for your local installation. pg_config is not meant for client bindings.

So I would kindly ask to reopen this bug.

[darix]

https://pypi.org/project/pkgconfig/

[dvarrazzo]

I can keep it open as a feature request but I'm not keen to dedicate personal time to this change.

[donaldguy]

pkg-config would also save some pain for building on macOS with homebrew openssl

I have export PKG_CONFIG_PATH="/usr/local/opt/openssl/lib/pkgconfig" in my dotfiles

but that was no dice here.

I had to set an explicit

export CPPFLAGS="-I/usr/local/opt/openssl/include"

to get psycopg2 to build when everything else has been able to find it

[darix]

Does pkg-config --libs --cflags openssl give you the correct data?

[dvarrazzo]

#1315 shows how less maintainable a pkg-config solution is compared to pg_config.