Re: Request and Question about pkgconfig and related pkgs

On Sat, Jan 03, 2009 at 12:26:56AM +0900, Tomoaki Okayama wrote:
> Hello,
> 
> I would like to make a request and ask a question
> about pkgconfig.
> 
> 1. Why don't you remove the dependency on glib?
>  `glib' is obsolete, which should be replaced with `glib2'.
>  (some people hate to install glib)
>  And glib or glib2 feature may be not necessary for users,
>  so it is easier to simply remove it than to switch to glib2.

I will use "glib1" to mean "the old glib" to avoid confusion here...

pkg-config requires (glib1 or glib2) in order to parse .pc files, and
glib2:BuildDepends:pkgconfig, so there is no clean solution as you
would like.

To switch to glib2 and avoid being circular, either pkg-config must
not use glib2 or the glib2 build must not use pkg-config.

The pkg-config distro actually contains its own full set of glib1
sources and can use them instead of relying on external glib2.
Actually, the ability to use external glib1 is a fink hack. By
default, pkg-config uses existing system-supplied glib2, which we
don't have, or included glib1 source. So if we just wanted to break
the dependency on external glib1 package, we could use that instead.
But that's silly...we still wind up building glib1 and having its
library, but (i) without any fink improvements, patches, etc. (ii) in
duplicate if user does have anything else that uses glib1 and (iii)
repeatedly every time a new pkg-config package is released.

Since back to glib-2.0, glib2 configure does check for pkg-config
being available. At this time (glib-2.18.2) that result is not used
for anything (reading .pc files, determinging pathnames, etc.), but
there are public .m4 macros that do use it. So for now, we could patch
glib2 to avoid the BD:pkgconfig and switch pkg-config to use
glib2. However, there is no guarantee that in the future, glib2 might
not actually use pkg-config for something substantial that would be
difficult or fragile to patch. Would be useful to file a gnome
bugzilla about it being needed *only* by glib2 runtime files, not at
glib2's build, which may not happen on the same machine and therefore
does not truly enforce anything useful.

> 2. Is "Depends: pkgconfig" good?
>  Some packages, for example shared-mime-info and gtk-doc, Depends
>  (not BuildDepends) on pkgconfig, just because the packages contain
>  *.pc files. I don't think they truly `Depends' on pkgconfig...
>  The packages in debian don't depend on pkgconfig, see:
>   http://packages.debian.org/sid/shared-mime-info
>   http://packages.debian.org/sid/gtk-doc-tools
>  If the dependency on pkgconfig is not necessary, it would be
>  advisable to remove it from the packages.
>  Could it be overkill to mark "BuildDependsOnly: True" on pkgconfig? :-}

There is a whole fink-wiki page with info about when and why one might
want Depends:pkgconfig in a package that supplies .pc files. I'm not
back to a machine that has CVS yet, but will add the wiki URL to
DescUsage soon.

BDO:true is bad overkill (even without the previous answer). Some
packages do use pkgconfig at runtime (example: the perl bindings
package for it).

To turn around the question: why would one *not* want to have
Depends:pkgconfig?

dan

-- 
Daniel Macks
[email protected]
http://www.netspace.org/~dmacks


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