[CMake] [RFC] How to use pkg-config under Windows (... and OSX)?

[Alexander Neundorf]

On Friday 18 November 2011, Patrick Spendrin wrote:
> Am 18.11.2011 02:02, schrieb Alan W. Irwin:
> > Alex, is it possible your KDE Windows developers who are objecting to
> > pkg-config tried a version from years ago when it did not have all
> > these Windows issues sorted out? I suggest you tell them to
> > investigate again using modern pkg-config.  For example, they could
> > follow the experiment I tried using the all-in-one GTK+ 2.22.1 bundle
> > you can download from http://www.gtk.org/download/win32.php.  If that
> > works (which it should do if the bundle is properly installed) or if
> > they use a modern binary version of pkg-config for Windows from that
> > same location, ask them to attempt to find any Windows binary package
> > that is broken with regard to pkg-config. There might be some of
> > those.  But I very much doubt that is a systematic problem since it is
> > so straightforward (install the *.pc files in the correct relative
> > location in the install tree) to deal with the pkg-config Windows
> > issue the KDE Windows developers have been so concerned about.
> 
> First I want to explain our setup again a bit more:
> KDE on Windows is built using two compilers, gcc from the mingw-w64
> project (both 32bit and 64bit) and the no-charge Microsoft compiler
> (Visual Studio Express Edition). Since there are problems with the
> compatibility of C++ libraries and for easier debugging, we build all
> depend packages ourselves with each compiler (so there are multiple
> packages even for C libraries). For that, we sometimes add heavy patches
> to those libraries (adaptions to the regular Unix layout for all
> compilers even for msvc built libraries e.g.). These patches normally
> don't add a missing .pc file.

If there is no .pc file, then pkg-config doesn't return anything, and the 
find_library() etc. calls simply search as they always do, without the hints 
from pkg-config.
That's fine, since the find-modules must also work properly at least for 
standard installs if pkg-config is not installed at all.

> One of the other problems still persists - pkg-config is not needed for
> those packages now (think of standard build libz which also installs a
> .pc file). So for us the question is of course whether there is a real
> need to add an additional thing to the build system.

I agree to that. The find-modules should, at least for normal installs, also 
work without pkg-config.
But they also should not fail if pkg-config is there and returns something for 
a normal install.
If there are such failures, we need to do something about them.

> I will try to check with newer builds of pkg-config this weekend though.

Did you have time to do that ?
How did it work out ?

Alex