Re: Finding dependencies in lib64 or lib

[Ralf Corsepius]

On 02/11/2010 03:14 PM, Daniel Pocock wrote:
> Ralf Corsepius wrote:
>    
> > On 02/11/2010 12:37 PM, Daniel Pocock wrote:
> >      
> > > Hi,
> > >
> > > I've been looking over configure.in for the Ganglia project.
> > >
> > > The project depends on some other libs, and their locations can be
> > > specified with configure arguments, for example:
> > >
> > > --with-libconfuse=/usr/local
> > >
> > > The original configure.in would then try -L/usr/local/lib
> > >
> > > However, there are platforms where 64 bit libraries should be in
> > > */lib64, e.g. the search for libconfuse should try /usr/local/lib64 on
> > > those platforms.
> > >
> > > My initial solution is to test $host
> > >
> > > LIB_SUFFIX=lib
> > > case $host in
> > > x86_64-redhat-linux*)
> > >     LIB_SUFFIX=lib64
> > > esac
> > >
> > > but a proper solution
> > >        
> > A proper solution is not to try tricks like the one above, but to let
> > the user specify the directory he needs, if he needs special settings.
> >
> > In most cases he won't have to, because on e.g. on redhat-based systems,
> > /usr/lib64 is in of GCC's default library search path.
> >      
> It is not quite so simple

It is

> - the third party library may be installed
> elsewhere, e.g. /opt/confuse-2.6/lib64
>    

configure LDFLAGS=-L/opt/confuse-2.6/lib64
> The --with-libconfuse option only accepts the base directory (e.g.
> --with-libconfuse=/opt/confuse-2.6)
Well, your approach is broken :)

On a wider scale, it is even more broken than you might think:

The fact some systems use "lib64" actually is arbitrary. The, what you 
call "LIB_SUFFIX" is a more or less arbitrary chosen convention of the 
OS vendor.

Many embedded system's compilers e.g. use many multilibs, with many 
different library names.
Even some *nix'sh OSes do so (E.g. some sparc Solaris variants did (do? 
I don't have access to Solaris machines anymore) so).

>   and configure has to decide whether
> to append /lib or /lib64 to find the right dependencies.
>
> On some systems (e.g. a host used for building 32 and 64 bit packages),
> there may be two versions of libconfuse installed, e.g.
>
> /opt/confuse-2.6/lib/libconfuse.so (32 bit)
>    
configure LDFLAGS=-L/opt/confuse-2.6/lib \
  CPPFLAGS=-I/opt/confuse-2.6/include \
  CFLAGS="-g -O2 -m32" \
--libdir=/opt/confuse-2.6/lib
...

> /opt/confuse-2.6/lib64/libconfuse.so (64 bit)
>
> and our original configure.in would never look in the 64 bit directory.
>
>    
configure LDFLAGS=-L/opt/confuse-2.6/lib64 \
  CPPFLAGS=-I/opt/confuse-2.6/include \
  CFLAGS="-g -O2 -m64" \
--libdir=/opt/confuse-2.6/lib64
...

Ralf