Bug#833300: closed by Michael Biebl <biebl at debian.org> (Re: Bug#833300: libgtksourceview2.0-dev: Please depend on libpng-dev)

[Emilio Pozuelo Monfort]

On 03/08/16 11:44, Ximin Luo wrote:
> Michael Biebl:
>> Am 03.08.2016 um 02:24 schrieb Ximin Luo:
>>> Debian Bug Tracking System:
>>>> This is an automatic notification regarding your Bug report
>>>> which was filed against the libgtksourceview2.0-dev package:
>>>>
>>>> #833300: libgtksourceview2.0-dev: Please depend on libpng-dev
>>>>
>>>> It has been closed by Michael Biebl <biebl at debian.org>.
>>>>
>>>> Their explanation is attached below along with your original report.
>>>> If this explanation is unsatisfactory and you have not received a
>>>> better one in a separate message then please contact Michael Biebl <biebl at debian.org> by
>>>> replying to this email.
>>>>
>>>
>>> Hi Michael,
>>>
>>> Your explanation is insufficient - it does not communicate to readers why this is not a bug.
>>
>> It's not a bug in gtksourceview-2.0.pc because that file does not
>> declare a dependency on libpng. I've even copied the contents of that
>> file to make that clear.
>>
> 
> It's really unclear to me why this means "there is no bug". The logical jump here is too far, can you explain better please?
> 
> You should understand that most readers have less in-depth context about this program than you, so it is harder for other people to make "logical jumps" that might seem obvious to you.

libgtksourceview2.0-dev needs to depend on the packages that provide the .pc
files that its .pc file requires.

i.e., it should depend on what provides gtk+-2.0.pc and what provides libxml-2.0.pc.

The failure indicates that something is missing a dependency on libpng-dev, but
pkg-config is recursive. So when you do `pkg-config --cflags gtksourceview-2.0'
it will look for the cflags of required packages, recursively. And the package
that requires libpng is the one that should depend on it.

>>> Why do you think pkg-config exits with error code 1, when libpng-dev is not installed?
>>
>> You need to check that locally on your system. Run pkg-config with the
>> --debug flag and you should see where it exits.
>>
> 
> I did run it with the debug flag, and it exited exactly after trying to find libpng-dev. Although I pasted the original command line wrong in my first email, I've attached the full log as a separate file.

I see:

Searching for 'cairo' private requirement 'libpng'
Looking for package 'libpng'
Looking for package 'libpng-uninstalled'

So /usr/lib/x86_64-linux-gnu/pkgconfig/cairo.pc has:

Requires.private:    gobject-2.0 glib-2.0 >= 2.14       pixman-1 >= 0.30.0
fontconfig >= 2.2.95 freetype2 >= 9.7.3   libpng xcb-shm xcb >= 1.6 xcb-render
>= 1.6 xrender >= 0.6 x11 xext

However, it also depends on libpng-dev:

Depends: libcairo2 (= 1.14.6-1+b1), libcairo-gobject2 (= 1.14.6-1+b1),
libcairo-script-interpreter2 (= 1.14.6-1+b1), libfontconfig1-dev (>= 2.2.95),
libfreetype6-dev (>= 2.1.10), libx11-dev, libxrender-dev (>= 0.6), libxext-dev,
libpng-dev, libsm-dev, libpixman-1-dev (>= 0.22.0), libxcb1-dev (>= 1.6),
libxcb-render0-dev (>= 1.6), libxcb-shm0-dev, libglib2.0-dev

So the question here is: what version of libcairo2-dev do you have installed,
and why don't you have libpng-dev installed?

Emilio