how to configure.ac with optional GNU guile library ("--with-guile" ) - c

Question

I'm new to configure.ac, I'm trying to create a simple program that would only use the GNU guile library if the user invokes:
configure --with-guile
so the program would be something like:
#include "config.h"
#include <stdio.h>
#ifdef HAVE_GUILE
#include <libguile.h>
#endif
int main(int argc,char** argv) {
#ifdef HAVE_GUILE
printf("Guile supported\n");
scm_init_guile();
#else
printf("Guile not supported\n");
#endif
return 0;
}
GNU guile uses guile-config compile and guile-config link to obtain the path to the include directory and the libraries. I've not found a tutorial where the paths above are obtained via an external program.
So far my `configure.ac` is
AC_INIT(program, 1.0)
AC_PROG_CC
AC_CONFIG_HEADERS(config.h)
with_guile=no
AC_ARG_WITH(guile, [AS_HELP_STRING([--with-guile], [use gnu guile])],[],[with_guile=yes])
if test "x$with_guile" != no
then
AC_MSG_CHECKING(for Guile)
guile-config link > /dev/null || {
echo "configure: cannot find guile-config; is Guile installed?" 1>&2
exit 1
}
CFLAGS="$CFLAGS `guile-config compile`"
LDFLAGS="$LDFLAGS `guile-config link`"
AC_DEFINE([HAVE_GUILE],[1],[Guile supported])
#PKG_CHECK_MODULES([GUILE],[guile-2.0])
#AC_CHECK_HEADERS([libguile.h], [], [AC_MSG_ERROR([guile include files not found])])
#AC_CHECK_LIB([guile], [scm_with_guile], [AC_MSG_ERROR([guile library files not found])])
fi
dnl Process Makefile.in to create Makefile
AC_OUTPUT(Makefile)
I've removed AC_CHECK_HEADERS and AC_CHECK_LIB because they doesn't work (the files are not found).
Here I'm lost: how can I add the guile paths to CFLAGS and LDFLAGS, how can I generate HAVE_GUILE in config.h
current Makefile.in:
CC=#CC#
LD=#CC#
program: program.o
$(LD) -o $# $^
.PHONY: clean
clean:
rm -f program *.o

Answer 1

configure.ac:
AC_PROG_CC
AC_CONFIG_HEADERS([config.h])
AC_ARG_WITH(guile, [AS_HELP_STRING([--with-guile], [use gnu guile])],
[with_guile=yes],[with_guile=no])
AS_IF([test "x$with_guile" = xyes],
[AC_CHECK_PROG([GUILE_CONFIG],[guile-config],[guile-config])
AS_IF([test -z "$GUILE_CONFIG"],[AC_MSG_FAILURE([cannot find guile-config])])
CFLAGS="$CFLAGS `$GUILE_CONFIG compile`"
LDFLAGS="$LDFLAGS `$GUILE_CONFIG link`"
AC_DEFINE([HAVE_GUILE],[1],[Guile supported])])
AC_CONFIG_FILES([Makefile])
AC_OUTPUT
is more typical. I used a Makefile.am instead of what you did:
Makefile.am:
bin_PROGRAMS = program
program_SOURCES = src/main.c
which is more typical also.
config.h has:
/* config.h. Generated from config.h.in by configure. */
/* config.h.in. Generated from configure.ac by autoheader. */
/* Guile supported */
#define HAVE_GUILE 1
...
Makefile has:
...
CFLAGS = -g -O2 -pthread -I/usr/include/guile/2.0
...
LDFLAGS = -lguile-2.0 -lgc