Update macro to allow linking to libpython.so if libpython#.#.so doesn't exist

FIXME: order of printing nested check messages in macro is sub-optimal


git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@1323 3ecf2c5c-341e-0410-92b4-d18e462d057c

plugins/pyloader/m4/ac_python_devel.m4

@@ -148,8 +148,34 @@ $ac_distutils_result])
 
 		PYTHON_LDFLAGS=`$PYTHON -c "from distutils.sysconfig import *; \
 			from string import join; \
-			print '-L' + get_python_lib(0,1), \
+			print '-L' + get_python_lib(0,1);"`
-		      	'-lpython';"`$py_version
+
+      # We could have a versioned library, or an unversioned one,
+      # even if the second case is discouraged. So, let's check for
+      # the versioned one first, and fallback on the second later.
+      LIBS="$ac_save_LIBS $PYTHON_LDFLAGS"
+      CPPFLAGS="$ac_save_CPPFLAGS $PYTHON_CPPFLAGS"
+
+      AC_LANG_PUSH([C])
+		AC_CHECK_LIB([python$py_version], [Py_Initialize], 
+         [PYTHON_LDFLAGS="$PYTHON_LDFLAGS -lpython$py_version"],
+         AC_CHECK_LIB([python], [Py_Initialize],
+            [PYTHON_LDFLAGS="$PYTHON_LDFLAGS -lpython"],
+            [PYTHON_LDFLAGS=""])
+      )
+      AC_LANG_POP
+
+      if test -z "$PYTHON_LDFLAGS"; then
+         AC_MSG_ERROR([
+  Could not link test program to Python. Maybe the main Python library has been
+  installed in some non-standard library path. If so, pass it to configure, 
+  via the LDFLAGS environment variable.
+  Example: ./configure LDFLAGS="-L/usr/non-standard-path/python/lib"
+         ])
+      fi
+
+      CPPFLAGS="$ac_save_CPPFLAGS"
+      LIBS="$ac_save_LIBS"
 	fi		
 	AC_MSG_RESULT([$PYTHON_LDFLAGS])
 	AC_SUBST([PYTHON_LDFLAGS])
@@ -207,14 +233,12 @@ $ac_distutils_result])
 
    if test ! "$pythonexists" = "yes"; then
 	   AC_MSG_ERROR([
-  Could not link test program to Python. Maybe the main Python library has been
-  installed in some non-standard library path. If so, pass it to configure, 
-  via the LDFLAGS environment variable.
-  Example: ./configure LDFLAGS="-L/usr/non-standard-path/python/lib"
   ============================================================================
    ERROR!
    You probably have to install the development version of the Python package
    for your distribution.  The exact name of this package varies among them.
+   Take also a look to config.log. If everything looks all right, please
+   report the problem to the macro maintainer.
   ============================================================================
 	   ])
 	  PYTHON_VERSION=""