[Haskell-cafe] Cabal, xmonad-contrib, X11-xft, pkg-config ... questioning my sanity
jacek.generowicz at cern.ch
Mon Dec 6 15:39:26 CET 2010
Problem solved: 2 solutions described below.
On 2010 Dec 6, at 14:15, Duncan Coutts wrote:
> On 6 December 2010 11:02, Jacek Generowicz
> <jacek.generowicz at cern.ch> wrote:
>> It a appears that a program which does not exist on my computer
>> seems to
>> insist on a package version which does not exist in my universe, I'm
>> starting to wonder whether I have lost my marbles. Could some kind
>> please point me in some sensible direction?
>> cabal install xmonad-contrib
>> Resolving dependencies...
>> Configuring X11-xft-0.3...
>> cabal: pkg-config version >=0.9.0 is required but it could not be
>> X11-xft version 0.9.0 doesn't even exist, as far a I can tell
> In the development version of cabal we have changed that error message
> to try and make it clear that it is looking for a program called
> pkg-config, not a Haskell package or a C lib.
> cabal: The program pkg-config version >=0.9.0 is required but it
> could not be
> Do you think that message would have helped avoid your confusion?
Oooh, that's a difficult question to answer, as I had read your
earlier paragraph before coming to this question. After your
explanation explained the error message (to the extent that I now
wonder how on earth I ever took it to mean that it's looking for X11-
xft version >=0.9.0, when it quite clearly states "pkg-config version
>=0.9.0 is required but could not be found"), I have no idea whether
the new message would have been better.
> Is there an alternative message that would have been better?
Well, if I try to understand how I could have misunderstood the
original message, I suspect that it is because of the common style of
error message where the program generating the message precedes the
actual message on the same line, just like "cabal: ..." precedes the
message in this case. So I guess that I parsed it something like "...
pkg-config: version >=0.9.0 is required ..." and inferred that
'version' refers to the package mentioned in an earlier message.
In which case, maybe something like
cabal: version >=0.9.0 of pkg-config is required ...
would have prevented me from making this particular mistake in this
> pkg-config  is a tool used by C libraries to describe things like
> dependencies on other C libs and what C compiler flags are needed to
> use the packages.
> The Haskell package X11-xft is a binding to the C library xft. On most
> modern unix systems xft C library provides meta-data that pkg-config
> can use. For example, on my system I can run:
> $ pkg-config --cflags xft
> $ pkg-config --libs xft
> -lXft -lXrender -lfontconfig -lfreetype -lX11
> Cabal does exactly the same thing, to work out what flags are needed
> to use the xft C library.
> The problem on your system is that the pkg-config program is not
> installed. Perhaps on OSX it comes with Xcode, I'm not sure. It may
> well also be the case that you don't have the development files for
> X11 or xft installed either (e.g. C header files). Hopefully some OSX
> person can advise you on what you need to install to do X11
> development on OSX.
Solution 1 (more complicated version):
Although I never use XCode itself, I thought that I had it installed
along with all the developer tools in order to get at GCC etc.
Anyway, pkg-config seems to be available through darwinports, but I
don't use darwinports (as, many years ago, I concluded that it's more
trouble than it's worth, because of the strange places where it puts
the stuff it manages).
However, a plain manual compilation Just Works (for me):
tar zxf pkgconfig.tgz
sudo make install
and I now have pkg-config
If I try
pkg-config --cflags xft
it complains about the package not being found, and mentions the
relevant environment variable.
I *do* have /usr/X11/lib/pkgconfig/xft.pc, and popping its directiory
into PKG_CONFIG_PATH makes the above pkg-config call now work.
In this state,
cabal install xmonad-contrib
Solution 2 (simpler):
I did manage to get xmonad-contrib to cabal install (without pkg-
config) by asking for it not to use xft
cabal install xmonad-contrib --flags="-use_xft"
Presumably cabal uses pkg-config for only a subset of the things it
manages, and xft is the only one of those on which xmonad-contrib
Thank you Duncan for your concise, clear and complete answer: it was
just what I needed to unblock me.
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