Don't just look for python2. Instead, first look for python, and then

see whether it's Python 2 or not; if it's not, *then* look for Python 2.

That way, you can use Python on systems where python is Python 2 and
python2 doesn't exist.

Move the check for Python up after the check for Perl.  (All the program
checks arguably belong together.)

AC_PATH_PROG() does AC_SUBST() for you; don't do it ourselves.

svn path=/trunk/; revision=49253

configure.ac

@@ -44,7 +44,9 @@ AC_DEFINE(VERSION_MICRO, version_micro, [Wireshark's micro version])
 
 AM_DISABLE_STATIC
 
-dnl Checks for programs.
+#
+# Checks for programs used in the build process.
+#
 AC_PROG_CC
 AM_PROG_CC_C_O
 AC_PROG_CXX
@@ -54,6 +56,34 @@ AC_DEFUN([AC_PROVIDE_AC_LIBTOOL_DLOPEN], )
 AC_LIBTOOL_DLOPEN
 AC_PROG_LIBTOOL
 AC_PATH_PROG(PERL, perl)
+
+# Check for Python.
+AC_PATH_PROG(PYTHON, python)
+if test ! -z "$PYTHON"; then
+	#
+	# OK, we found Python; is it Python 2.x?
+	# Note: we don't use named components for sys.version_info to get
+	# the major version number, as named components for version_info
+	# were apparently introduced in Python 2.7.
+	#
+	AC_MSG_CHECKING([whether $PYTHON is Python 2])
+	python_major_version=`$PYTHON -c 'import sys; print sys.version_info[[0]]'`
+	if test "$python_major_version" = 2; then
+		AC_MSG_RESULT([yes])
+	else
+		#
+		# It's not 2.x.
+		#
+		AC_MSG_RESULT([no])
+
+		#
+		# Try looking for python2; if we find it, we assume it's
+		# Python 2
+		#
+		AC_PATH_PROG(PYTHON, python2)
+	fi
+fi
+
 #
 # XXX - should autogen.sh check for YACC/Bison and Flex?  A user building
 # from a distribution tarball shouldn't have to have YACC/Bison or Flex,
@@ -133,12 +163,6 @@ else
 	fi
 fi
 
-AC_SUBST(PERL)
-AC_SUBST(LEX)
-AC_SUBST(POD2MAN)
-AC_SUBST(POD2HTML)
-AC_SUBST(XMLLINT)
-
 #
 # Set "ac_supports_gcc_flags" if the compiler is known to support GCC-style
 # flags such as -pedantic, -W warning flags and -f feature flags.  Currently,
@@ -414,8 +438,6 @@ AC_PATH_PROG(LYNX, lynx)
 AC_CHECK_PROG(HAVE_LYNX, lynx, "yes", "no")
 AM_CONDITIONAL(HAVE_LYNX, test x$HAVE_LYNX = xyes)
 
-AC_PATH_PROG(PYTHON, python2)
-
 # Check for w3m (html -> text)
 AC_PATH_PROG(W3M, w3m)
 AC_CHECK_PROG(HAVE_W3M, w3m, "yes", "no")