[gnome-code-assistance] Use python3 if available

[Jesse van den Kieboom <jessevdk src gnome org>]

commit 4f2ac4800006ff8b60ee90b57e40fa0dc9cff4ec
Author: Jesse van den Kieboom <jessevdk gmail com>
Date:   Sat Nov 9 12:47:03 2013 +0100

    Use python3 if available

 backends/c/c.in           |    2 +-
 backends/python/python.in |    2 +-
 backends/xml/xml.in       |    2 +-
 configure.ac              |   33 ++++++++++++++++++++++-----------
 4 files changed, 25 insertions(+), 14 deletions(-)
---
diff --git a/backends/c/c.in b/backends/c/c.in
index 888753d..8147a29 100644
--- a/backends/c/c.in
+++ b/backends/c/c.in
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python PYTHON_VERSION_MAJOR@
 
 import sys
 sys.path.insert(0, '@GCA_PYBACKENDS_ROOT_EX@')
diff --git a/backends/python/python.in b/backends/python/python.in
index 20b8bfe..14ae7e2 100644
--- a/backends/python/python.in
+++ b/backends/python/python.in
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python PYTHON_VERSION_MAJOR@
 
 import sys
 sys.path.insert(0, '@GCA_PYBACKENDS_ROOT_EX@')
diff --git a/backends/xml/xml.in b/backends/xml/xml.in
index 9efbe0f..24b8ece 100644
--- a/backends/xml/xml.in
+++ b/backends/xml/xml.in
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python PYTHON_VERSION_MAJOR@
 
 import sys
 sys.path.insert(0, '@GCA_PYBACKENDS_ROOT_EX@')
diff --git a/configure.ac b/configure.ac
index a655a74..e2bff9f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,7 +11,11 @@ AC_CONFIG_HEADERS(config.h)
 AC_CONFIG_MACRO_DIR([m4])
 
 AM_PROG_LIBTOOL
-AM_PATH_PYTHON
+AM_PATH_PYTHON(3, [python_found=3], [python_found=no])
+
+if test "x$python_found" = "xno"; then
+       AM_PATH_PYTHON(2, [python_found=2])
+fi
 
 AM_INIT_AUTOMAKE([1.11 tar-ustar dist-xz no-dist-gzip -Wno-portability subdir-objects])
 AM_MAINTAINER_MODE([enable])
@@ -55,21 +59,21 @@ AM_CONDITIONAL(ENABLE_DEBUG, test "x$enable_debug" = "xyes")
 dnl ================================================================
 dnl python support
 dnl ================================================================
-if test "x$PYTHON" != "x"; then
+if test "x$python_found" != "xno"; then
        AC_MSG_CHECKING([python dbus])
        $PYTHON -c 'import dbus' 2>/dev/null
        if test $? -ne 0 ; then
                AC_MSG_RESULT([no])
-               PYTHON=
+               python_found=no
        else
                AC_MSG_RESULT([yes])
        fi
 fi
 
-if test "x$PYTHON" != "x"; then
+if test "x$python_found" != "xno"; then
        PKG_CHECK_EXISTS([pygobject-3.0],
                         [],
-                        [PYTHON=])
+                        [python_found=no])
 fi
 
 AM_CONDITIONAL(PYTHON_ENABLE, test "x$PYTHON" != "x")
@@ -89,7 +93,7 @@ if test "x$enable_c" = "xauto"; then
 
        AC_MSG_CHECKING([c backend])
 
-       if test "x$PYTHON" = "x" || test "x$LLVM_CONFIG" = "x"; then
+       if test "x$python_found" = "xno" || test "x$LLVM_CONFIG" = "x"; then
                AC_MSG_RESULT([no])
                enable_c=no
        else
@@ -103,7 +107,7 @@ elif test "x$enable_c" != "xno"; then
 
        if test "x$LLVM_CONFIG" = "x"; then
                AC_MSG_ERROR([llvm-config not found])
-       elif test "x$PYTHON" = "x"; then
+       elif test "x$python_found" = "xno"; then
                AC_MSG_ERROR([python not found])
        else
                AC_MSG_RESULT([yes])
@@ -132,7 +136,7 @@ AC_ARG_ENABLE([python],
 AC_MSG_CHECKING([python backend])
 
 if test "x$enable_python" = "xauto"; then
-       if test "x$PYTHON" = "x"; then
+       if test "x$python_found" = "xno"; then
                AC_MSG_RESULT([no])
                enable_python=no
        else
@@ -140,7 +144,7 @@ if test "x$enable_python" = "xauto"; then
                enable_python=yes
        fi
 elif test "x$enable_python" != "xno"; then
-       if test "x$PYTHON" = "x"; then
+       if test "x$python_found" = "xno"; then
                AC_MSG_ERROR([python not found])
        else
                AC_MSG_RESULT([yes])
@@ -264,7 +268,7 @@ AC_ARG_ENABLE([xml],
 AC_MSG_CHECKING([xml backend])
 
 if test "x$enable_xml" = "xauto"; then
-       if test "x$PYTHON" = "x"; then
+       if test "x$python_found" = "xno"; then
                AC_MSG_RESULT([no])
                enable_xml=no
        else
@@ -272,7 +276,7 @@ if test "x$enable_xml" = "xauto"; then
                enable_xml=yes
        fi
 elif test "x$enable_xml" != "xno"; then
-       if test "x$PYTHON" = "x"; then
+       if test "x$python_found" = "xno"; then
                AC_MSG_ERROR([python not found])
        else
                AC_MSG_RESULT([yes])
@@ -422,6 +426,13 @@ AC_SUBST(GCA_JSBACKENDS_DIR)
 adl_RECURSIVE_EVAL("$GCA_JSBACKENDS_DIR", [GCA_JSBACKENDS_DIR_EX])
 AC_SUBST(GCA_JSBACKENDS_DIR_EX)
 
+if test "x$python_found" != "xno"; then
+       PYTHON_VERSION_MAJOR=$python_found
+else
+       PYTHON_VERSION_MAJOR=
+fi
+
+AC_SUBST(PYTHON_VERSION_MAJOR)
 
 AC_CONFIG_FILES([
 Makefile