pkg-config version confusion

[Dan Kegel]

On Wed, Jan 3, 2018 at 10:27 PM, Jeffrey Walton <noloader at gmail.com> wrote:
> When I check my Fedora 26 x86_64 machine:
>
>     $ command -v pkg-config
>     /bin/pkg-config
>     $ pkg-config --version
>     1.3.12
>
> But when I check the pkg-config download at
> https://pkgconfig.freedesktop.org/releases are it says the latest
> version is 0.29.2 from MARCH 2017.
>
> Does anyone know what is going on with the version information? Is
> 1.3.12 newer or older than 0.29.2?

There are two different implementations:

https://github.com/pkgconf/pkgconf is a reimplementation of
https://pkgconfig.freedesktop.org/

dank at hp500:~$ apt-cache policy pkgconf pkg-config
pkgconf:
  Installed: (none)
  Candidate: 0.9.12-6
pkg-config:
  Installed: 0.29.1-0ubuntu2
  Candidate: 0.29.1-0ubuntu2

The origin of the second one was a desire for one
that built without circular dependencies, iirc.
- Dan