Re: issue with AC_CHECK_LIB...

[Bob Friesenhahn]

On Wed, 30 Jun 2004, Chris Bowlby wrote:

> Hi Bob,
>
> That would explain why that was not working, though I do see other 
> application that are using that method with success, which is where I got the 
> idea from. Would you be able to provide me with an example on how I could 
> link in the function into the configure.ac file (I can write the function, 
> but I'm not certain how to link that into the test system). Where would I 
> need to store that function in order for it to be called?

I was going to suggest using AC_TRY_LINK but for some reason I can't 
find it in the Autoconf documentation anymore.  Instead I see a 
AC_LINK_IFELSE macro which must be used in conjunction with 
AC_LANG_PROGRAM.  Maybe AC_TRY_LINK has been retired.

Unfortunately, I do not have time to write an example.  I think that 
almost any compilable code fragment which lacks a main routine will 
serve as a test.  You would temporarily add the library to be tested 
to LIBS.  If you have a successful link, then a main() routine was 
found somewhere.

This special case seems to occur often so perhaps Autoconf should 
provide a macro to support it, or substitute different code if the 
function name tested is 'main'.

Bob

> At 06:10 PM 6/30/2004, Bob Friesenhahn wrote:
> > Sorry, you can not test for the function "main" in a library using 
> > AC_CHECK_LIB.  That is probably the only function you can not test for. 
> > The reason is that AC_CHECK_LIB writes a test program which provides its 
> > own main.
> >
> > You could write your own test program which is missing a main() function 
> > and try compiling/linking it instead.
> >
> > Bob
> >
> > On Wed, 30 Jun 2004, Chris Bowlby wrote:
> >
> > > Hi All,
> > >
> > > I've been pegging away with a configure script for the last month or so 
> > > and feel that I'm getting a good understanding of how things are 
> > > working, however I've got one issue that I've been trying to figure out 
> > > for the last few hours and I've tried every suggestion I could find on 
> > > the net. My issue is that I'm trying to use:
> > >
> > > AC_CHECK_LIB([stlport_gcc], [main])
> > > AC_CHECK_LIB([pqxx], [main])
> > >
> > > within the configure script, defining:
> > >
> > > SRCH_INC="/usr/local/include /usr/include"
> > > SRCH_LIB="/usr/local/lib /usr/lib"
> > >
> > > #
> > > # Include directories
> > > #
> > > ac_save_IFS=$IFS
> > > IFS="${IFS}:"
> > > # SRCH_INC comes from the template file
> > > for dir in $with_includes $SRCH_INC; do
> > >  if test -d "$dir"; then
> > >    INCLUDES="$INCLUDES -I$dir"
> > >  else
> > >    AC_MSG_WARN([*** Include directory $dir does not exist.])
> > >  fi
> > > done
> > > IFS=$ac_save_IFS
> > > AC_SUBST(INCLUDES)
> > >
> > >
> > > #
> > > # Library directories
> > > #
> > > ac_save_IFS=$IFS
> > > IFS="${IFS}:"
> > > # LIBRARY_DIRS comes from command line, SRCH_LIB from template file.
> > > for dir in $LIBRARY_DIRS $SRCH_LIB; do
> > >  if test -d "$dir"; then
> > >    LIBDIRS="$LIBDIRS -L$dir"
> > >  else
> > >    AC_MSG_WARN([*** Library directory $dir does not exist.])
> > >  fi
> > > done
> > > IFS=$ac_save_IFS
> > >
> > > CPPFLAGS="$CPPFLAGS $INCLUDES"
> > > LDFLAGS="$LDFLAGS $LIBDIRS"
> > >
> > > AC_MSG_NOTICE([using CPPFLAGS=$CPPFLAGS])
> > > AC_MSG_NOTICE([using LDFLAGS=$LDFLAGS])
> > >
> > > before I even process the check lib macro's. No matter what I do I 
> > > always get:
> > >
> > > checking for main in -lstlport_gcc... no
> > > checking for main in -lpqxx... no
> > >
> > > And I know the files are located within the path stucture defined by the 
> > > library search path before I call AC_CHECK_LIB.
> > >
> > > > ls -al /usr/local/lib/libpqxx*
> > > -rwxr-xr-x  1 root  wheel   7265864 Jun 30 11:36 
> > > /usr/local/lib/libpqxx-2.2.3.so
> > > -rw-r--r--  1 root  wheel  15174818 Jun 30 11:36 
> > > /usr/local/lib/libpqxx.a
> > > -rwxr-xr-x  1 root  wheel       865 Jun 30 11:36 
> > > /usr/local/lib/libpqxx.la
> > > lrwxr-xr-x  1 root  wheel        16 Jun 30 11:36 
> > > /usr/local/lib/libpqxx.so -> libpqxx-2.2.3.so
> > >
> > >
> > > > ls -al /usr/local/lib/libstlport*
> > > -rwxr-xr-x  1 root  wheel   1586106 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc.a
> > > lrwxr-xr-x  1 root  wheel        21 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc.so -> libstlport_gcc.so_4_5
> > > -rwxr-xr-x  1 root  wheel    684045 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc.so_4_5
> > > -rwxr-xr-x  1 root  wheel  15271126 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc_stldebug.a
> > > lrwxr-xr-x  1 root  wheel        30 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc_stldebug.so -> 
> > > libstlport_gcc_stldebug.so_4_5
> > > -rwxr-xr-x  1 root  wheel   7392400 Jun 30 11:02 
> > > /usr/local/lib/libstlport_gcc_stldebug.so_4_5
> > >
> > > I am royally stuck as I can not compile my app due to missing 
> > > references, this worked a few days ago, but today it does not.... Does 
> > > anyone have any suggestions?
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Autoconf mailing list
> > > address@hidden
> > > http://lists.gnu.org/mailman/listinfo/autoconf
> >
> > ======================================
> > Bob Friesenhahn
> > address@hidden
> > http://www.simplesystems.org/users/bfriesen

======================================
Bob Friesenhahn
address@hidden
http://www.simplesystems.org/users/bfriesen