[Fontconfig] @CONFIGDIR@ (usually /etc/fonts/conf.d) could be recorded in fontconfig.pc?

[suzuki toshiya]

Dear Tagoh-san,

Akira TAGOH wrote:
>> when confdir variable was introduced, confdir was @confdir@ (2010).
>> https://cgit.freedesktop.org/fontconfig/commit/fontconfig.pc.in?id=81b542b50f82f8a0ad9f38f7d913fe5433631166

When @confdir@ variable in fontconfig.pc was introduced by this commit,
@confdir@ in configure.ac was set to ${sysconfdir}/fonts.
It was configurable by "--with-confdir" option.

The directory /etc/fonts/conf.d was pointed by ${confddir} make variable,
it was hardwired to be ${confdir}/conf.d by conf.d/Makefile.am.
This ${confddir} make variable was invisible for configure script,
so it was not configurable.

It seems that the location of fonts.conf could be hard-to-find
for Mac OS X users, like the discussion in,

https://stackoverflow.com/questions/41720642/where-does-homebrew-install-fontconfigs-fonts-conf

But I'm unsure whether the developers working with Mac OS X want
pkg-config to inform @confdir at .

To decide the way "incompatible-but-better-naming" or "compatible-
but-confusing-naming", what I can contribute? One of my ideas is
that crawling all configure scripts (from MacPorts? from Homebrew?)
of the packages with build-dependency to fontconfig and count how
many packages checks @confdir@ value from fontconfig.pc. If there
is no, changing the definition of "confdir" might be considerable
idea.

It's easy for me to make a list of the packages with build-dependency
to fontconfig on Debian and its derivatives (*), but I'm less
familiar with MacPorts, Homebrew etc. If it's important, please
let me spend more time, I'm quite sorry.

(*)
curl -s http://ftp.jp.debian.org/debian/dists/testing/main/source/Sources.xz |
xz -cd | sed -n "/^Build-Depends: .*libfontconfig1-dev/p" | wc -l
returns 96, so the number of Debian packages to be checked
is less than 100, if the database is complete.

>> Daniel Macks reported this confdir was a bug, and corrected to @baseconfdir@ (2012).
>> https://cgit.freedesktop.org/fontconfig/commit/fontconfig.pc.in?id=ebd5096abc495550596861b6af2aae067e861553

Before this commit, there was a commit
https://cgit.freedesktop.org/fontconfig/commit/fontconfig.pc.in?id=e181ab4de5d20fe1f70e68f66ef8332553eba206
It replaced "--with-confdir" option by multiple options,
"--with-templatedir", "--with-baseconfigdir", "--with-configdir" and "--with-xmldir"
to configure related directories with more fine granularity.

Because of the removal of "--with-confdir" by this commit,
Daniel submitted his patch to replace missing @confdir@ by new
@baseconfigdir@ as follow-up action.

Regards,
mpsuzuki