Xapian devel - Jan 2006 - xapian-config --libs outputs libstdc++.la as a dependency

Hello,

I am hearing of users having trouble linking with libxapian (on slackware
and gentoo systems, and 0.9.2 I think), and I am not too sure where the
problem comes from, or what the correct solution could be, so I am just
asking here in case someone has a quick answer.

What happens is that "xapian-config --libs" outputs libstdc++.la in
the
list of libraries. Something like:

-L/usr/i686-pc-linux-gnu/bin -L/usr/i686-pc-linux-gnu/lib \
 /usr/lib/gcc/i686-pc-linux-gnu/3.4.4/libstdc++.la 

As recoll is linked with g++, this generates an error (I guess it might
work if libtool was used?).

The libstdc++ data seems to come from libxapian.la ('dependency_libs'
variable).

I don't see this happening on any on my systems (FreeBSD, Solaris, Redhat
7.3, Fedora core 4), so I guess I'll have to install gentoo somewhere to
look into this, except if someone here can tell me what goes wrong and what
I could do about it.

I am pasting a libxapian.la (from a gentoo system) at the end of this message.

Regards,

J.F. Dockes


# libxapian.la - a libtool library file
# Generated by ltmain.sh - GNU libtool 1.5.18 (1.1220.2.245 2005/05/16 08:55:27)
#
# Please DO NOT delete this file!
# It is necessary for linking the library.

# The name that we can dlopen(3).
dlname='libxapian.so.8'

# Names of this library.
library_names='libxapian.so.8.0.0 libxapian.so.8 libxapian.so'

# The name of the static archive.
old_library='libxapian.a'

# Libraries that this one depends upon.
dependency_libs=' -L/usr/i686-pc-linux-gnu/bin -L/usr/i686-pc-linux-gnu/lib
/usr/lib/gcc/i686-pc-linux-gnu/3.4.4/libstdc++.la'

# Version information for libxapian.
current=8
age=0
revision=0

# Is this an already installed library?
installed=yes

# Should we warn about portability when linking against -modules?
shouldnotlink=no

# Files to dlopen/dlpreopen
dlopen=''
dlpreopen=''

# Directory that this library needs to be installed in:
libdir='/usr/lib'

On Fri, Jan 13, 2006 at 07:48:10AM +0100, Jean-Francois Dockes
wrote:
> What happens is that "xapian-config --libs" outputs libstdc++.la
in the
> list of libraries. Something like:
> 
> -L/usr/i686-pc-linux-gnu/bin -L/usr/i686-pc-linux-gnu/lib \
>  /usr/lib/gcc/i686-pc-linux-gnu/3.4.4/libstdc++.la 
Hmm, that's not good.

I guess we need to recursively check for .la files in dependency_libs
and substitute the actual library to link against, plus the contents of
the .la file's dependency_libs.  That's a bit fiddly though...

We might be able to get away with just dropping libstdc++.la, since
linking C++ code should pull it in anyway.  I can't see any other
.la files making it in there unless we start depending on other
libraries.

Anyway, I'll take a look.
> As recoll is linked with g++, this generates an error (I guess it might
> work if libtool was used?).
If you're using libtool, then xapian-config --ltlibs should be used
instead (which happens automatically if you use XO_LIB_XAPIAN in
configure.in/configure.ac and use AC_PROG_LIBTOOL or AM_PROG_LIBTOOL).

Cheers,
    Olly