pkg-config version confusion

[Jeffrey Walton]

On Fri, Jan 5, 2018 at 12:53 PM, William Pitcock
<nenolod at dereferenced.org> 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?
>
> This is pkgconf 1.3.12 (my implementation).  Some distributions use it
> now because they can take advantage of libpkgconf in various build
> tools, etc.
>
> 1.3 is the latest release of pkgconf 1.3 series, there is also a 1.4
> series that recently went into Fedora rawhide.

Thanks William.

Please forgive my ignorance with these questions.

When upgrading pkg-config, what are the rules of the road? Should we
stay with the original lineage (Freedesktop vs Pitcock); or can they
be mixed and matched? That is, are these valid transitions/upgrades:

* Start with Freedesktop -> move to Pitcock
* Start with Pitcock -> move to Freedesktop

Sorry again to ask. I need to know what I am allowed to do when I am
told to update pkg-config.

Jeff