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pkg-config: required as dep so often - How and where to report?

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  pkg-config: required as dep so often - How and where to report? Alexander Traud <pabstraud@compuserve.com> - 2018-05-04 15:50 +0200
    Re: pkg-config: required as dep so often - How and where to report? Greg Wooledge <wooledg@eeg.ccf.org> - 2018-05-04 16:00 +0200
      Re: pkg-config: required as dep so often - How and where to report? Sven Joachim <svenjoac@gmx.de> - 2018-05-04 17:30 +0200
        Re: pkg-config: required as dep so often - How and where to report? Greg Wooledge <wooledg@eeg.ccf.org> - 2018-05-04 17:40 +0200
    Re: pkg-config: required as dep so often - How and where to report? Sven Joachim <svenjoac@gmx.de> - 2018-05-04 17:50 +0200
      Re: pkg-config: required as dep so often - How and where to report? Alexander Traud <pabstraud@compuserve.com> - 2018-05-05 12:40 +0200
    Re: pkg-config: required as dep so often - How and where to report? deloptes <deloptes@gmail.com> - 2018-05-05 20:50 +0200
    Re: pkg-config: required as dep so often - How and where to report? Alexander Traud <pabstraud@compuserve.com> - 2018-06-11 13:40 +0200

#195279 — pkg-config: required as dep so often - How and where to report?

To compile a (quite large) project, I had to install several packages
(dependencies). The project required the tool pkg-config. However, that
was not mentioned anywhere. Still the project compiled/built, because
one of the other dependencies (libsrtp2-dev) installed pkg-config as
side effect. So, I had pure luck that it succeeded.

When a package declares another package as "Depends" or "Recommends" in
the file "control.in", it gets installed as side effect (Debian Policy).

However, libsrtp2-dev needs pkg-config only when I compile it myself.
Consequently, pkg-config should be declared just as Build-Depends. This
is a minor bug, I am going to report with that package. However then, I
investigated a bit more and found seven (optional) dependencies of that
project which would have installed pkg-config as a side effect too. OK,
this is a bigger issue. Then I investigated further:

$ apt-cache rdepends --no-suggests pkg-config

On Ubuntu 18.04 LTS, this gives me 250 development packages (-dev)
which install pkg-config as a side effect.

$ apt-cache rdepends --no-recommends --no-suggests pkg-config

Still 186 packages.

Those packages come with a .pc file. However, the tool pkg-config should
be "suggested" and not "required". Yes, this is a minor issue. However,
this looks like a broad issue. How and where do I report something broad
like this? Is there somebody which takes over or do I have to report
this 250 times? Perhaps this qualifies even for an update of the
Debian Policy like adding an example: pkg-config should be maximum of
"Suggests" when .pc file exists, even when "Build-Depends" included
pkg-config.

Or am I on the complete wrong track and this is not even a minor bug?

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#195280

On Fri, May 04, 2018 at 03:48:26PM +0200, Alexander Traud wrote:
> To compile a (quite large) project, I had to install several packages
> (dependencies). The project required the tool pkg-config. However, that
> was not mentioned anywhere. Still the project compiled/built, because
> one of the other dependencies (libsrtp2-dev) installed pkg-config as
> side effect. So, I had pure luck that it succeeded.

libc6-dev depends on pkg-config, and build-essential depends on libc6-dev.

So I don't think it's necessary.  You're allowed to assume build-essential
is installed, I believe.

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#195282

On 2018-05-04 09:58 -0400, Greg Wooledge wrote:

> On Fri, May 04, 2018 at 03:48:26PM +0200, Alexander Traud wrote:
>> To compile a (quite large) project, I had to install several packages
>> (dependencies). The project required the tool pkg-config. However, that
>> was not mentioned anywhere. Still the project compiled/built, because
>> one of the other dependencies (libsrtp2-dev) installed pkg-config as
>> side effect. So, I had pure luck that it succeeded.
>
> libc6-dev depends on pkg-config,

Huh?  No it doesn't:

$ apt-cache show libc6-dev | grep Depends
Depends: libc6 (= 2.27-3), libc-dev-bin (= 2.27-3), linux-libc-dev

Cheers,
       Sven

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#195283

On Fri, May 04, 2018 at 05:26:22PM +0200, Sven Joachim wrote:
> On 2018-05-04 09:58 -0400, Greg Wooledge wrote:
> 
> > On Fri, May 04, 2018 at 03:48:26PM +0200, Alexander Traud wrote:
> >> To compile a (quite large) project, I had to install several packages
> >> (dependencies). The project required the tool pkg-config. However, that
> >> was not mentioned anywhere. Still the project compiled/built, because
> >> one of the other dependencies (libsrtp2-dev) installed pkg-config as
> >> side effect. So, I had pure luck that it succeeded.
> >
> > libc6-dev depends on pkg-config,
> 
> Huh?  No it doesn't:
> 
> $ apt-cache show libc6-dev | grep Depends
> Depends: libc6 (= 2.27-3), libc-dev-bin (= 2.27-3), linux-libc-dev

Oh, sorry.  I used apt-cache show libc6-dev and saw the super long list
of packages and versions that includes pkg-config, and missed the fact
that it was a Breaks: line instead of a Depends: line.

wooledg:~$ apt-cache depends libc6-dev
libc6-dev
  Depends: libc6
  Depends: libc-dev-bin
    libc-dev-bin:i386
  Depends: linux-libc-dev
  Conflicts: <libc0.1-dev>
  Conflicts: <libc0.3-dev>
  Conflicts: <libc6.1-dev>
  Breaks: binutils
  Breaks: <binutils-gold>
  Breaks: cmake
  Breaks: <gcc-4.4>
  Breaks: <gcc-4.5>
  Breaks: <gcc-4.6>
  Breaks: libhwloc-dev
  Breaks: libjna-java
  Breaks: liblouis-dev
  Breaks: liblouisxml-dev
  Breaks: make
  Breaks: pkg-config
  Suggests: glibc-doc
  Suggests: manpages-dev

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#195284

On 2018-05-04 15:48 +0200, Alexander Traud wrote:

> To compile a (quite large) project, I had to install several packages
> (dependencies). The project required the tool pkg-config. However, that
> was not mentioned anywhere. Still the project compiled/built, because
> one of the other dependencies (libsrtp2-dev) installed pkg-config as
> side effect. So, I had pure luck that it succeeded.
>
> When a package declares another package as "Depends" or "Recommends" in
> the file "control.in", it gets installed as side effect (Debian Policy).

In debian/control, not control.in.  And Recommends may or not be
installed, depending on the admin's decision.

> However, libsrtp2-dev needs pkg-config only when I compile it myself.

I'm not sure I can parse that.  The libsrtp2-dev package surely both
depends and build-depends on pkg-config.

> Consequently, pkg-config should be declared just as Build-Depends. This
> is a minor bug, I am going to report with that package. However then, I
> investigated a bit more and found seven (optional) dependencies of that
> project which would have installed pkg-config as a side effect too. OK,
> this is a bigger issue. Then I investigated further:
>
> $ apt-cache rdepends --no-suggests pkg-config
>
> On Ubuntu 18.04 LTS, this gives me 250 development packages (-dev)
> which install pkg-config as a side effect.
>
> $ apt-cache rdepends --no-recommends --no-suggests pkg-config
>
> Still 186 packages.
>
> Those packages come with a .pc file. However, the tool pkg-config should
> be "suggested" and not "required".

This very much depends on the package.  If you cannot just link against
libfoo with -lfoo but need special linker flags, then IMHO libfoo-dev is
well advised to add pkg-config to Depends, for instance.

,----
| $ pkg-config --libs gtk+-3.0
| -lgtk-3 -lgdk-3 -lpangocairo-1.0 -lpango-1.0 -lfribidi -latk-1.0 -lcairo-gobject -lcairo -lgdk_pixbuf-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0
`----

You cannot really expect anyone to get this right without pkg-config,
and so libgtk-3-dev depends on pkg-config.

Cheers,
       Sven

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#195296

>> libsrtp2-dev needs pkg-config only when I compile it myself.
> The libsrtp2-dev package surely both depends and build-depends on
> pkg-config.

Yes, the package description (debian/control) does. The created files do
not. I can compile, link, and run with libsrtp2.so without pkg-config.

Actually for this package, the result of pkg-config is wrong (--cflags
is empty, --libs lists -lpcap unnecessarily). However, that is another
issue (although it might be the cause why it was declared as Depends).

> [For libgtk-3-dev y]ou cannot really expect anyone to get this right
> without pkg-config, and so libgtk-3-dev depends on pkg-config.

Yes, my assumption might not be right for every package in that list.
Therefore, I would love to see someone more experienced taking over this
issue. Your argument is a strong argument for at least Suggests.
However, even in this example, pkg-config is not required. In such a
case, one can argue for Recommends instead of Suggests. Nevertheless,
I would not go for Depends.

That is what I am about. Perhaps someone sees a pattern and comes up
with a general rule. For example: "Every package with a pkgconfig/*.pc
file has to Suggest pkg-config†. If the shared library does not declare
its dependencies itself, and additional libraries are required to run
the shared library, pkg-config has to be Recommends. pkg-config should
never be Depends because the developer might have other means to build."
Again, the last sentence could be wrong if there is a dedicated config
tool in the package itself, which actually relies on pkg-config.

Another example: libxml2-dev » libicu-dev » libicu-le-hb-dev »
libharfbuzz-dev » libglib2.0-dev » pkg-config
Only because of the dependency graph, pkg-config must be installed.
Again, pkg-config is not required to compile/link against libxml2.
Actually, the package itself declares pkg-config just as Suggests.
Perhaps this is a bad example as well, because there is a bug in the
dependency graph. Anyway from that 250 packages, I have just looked
in-depth into libxml2 and libsrtp2, yet.

† That part of "my" rule would affect another several hundred packages.

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#195305

Alexander Traud wrote:

> Or am I on the complete wrong track and this is not even a minor bug?

IMO it is not really a bug, because I do not need pkg-config, to build some
peace of code. pkg-config is needed in case you use the build scripts that
require pkg-config, but the developer could not know which way you will go,
so I think it is OK to not have it anywhere.
Installing a *dev package suggest that you will use the header file. It does
not suggest that you will use build scripts that require pkg-config. For
example cmake projects offer macros that obsolete pkg-config and the
developer do not know what exactly you will use to build your project.

I see some developers put it in as suggested, depends or alike, but what is
exactly the problem with not having it somewhere. The fun with Linux is
that it is an adventure that never ends.
You can of course request putting it in as suggested for example.

regards

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#196558

On 04th of May 2018, Alexander Traud wrote:
<http://lists.debian.org/debian-user/2018/05/msg00048.html>
<http://issues.asterisk.org/jira/browse/ASTERISK-27555#comment-242108>

Do you have an idea, where I report this?

Do I report this just with those packages which affect me:
- libsrtp2-dev
- libglib2.0-dev
and they take over? Or do I report with somebody else, like another
mailing list?

By the way, how do I report correctly bugs in packages:
I am on Ubuntu and the originating package is libxml2-dev.
A) 4 reports: report on Ubuntu plus Debian and link those?
              report with libxml2 plus libglib2.0 and link those? Or
B) 1 report:  report just with the cause (Debian libglib2.0-dev)? Or
C) 2 reports: report just with Ubuntu and they report upstream.

Debian wrote:
> <http://www.debian.org/doc/manuals/maint-guide/dreq.html#control>
> <http://www.debian.org/doc/debian-policy/#document-ch-relationships>

I understand those documents in this way:
Not Depends but Recommends or Suggests.

deloptes wrote:
> You can of course request putting [pkg-config] in as suggested for
> example.

That is what I am about: Suggests. Especially because there are (at
least) three different pkg-config in the repository. I might want to
use another one.

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