Scripts in utils are now automatically converted. They may not work at the moment though

Makefile

@@ -2,17 +2,17 @@ PYTHON ?= python3
 
 export PYTHONPATH = $(shell echo "$$PYTHONPATH"):./sphinx
 
-.PHONY: all check clean clean-pyc clean-patchfiles pylint reindent test
+.PHONY: all check clean clean-pyc clean-patchfiles clean-generated pylint reindent test
 
 all: clean-pyc check test
 
-check:
+check: convert-utils
 	@$(PYTHON) utils/check_sources.py -i build -i dist -i sphinx/style/jquery.js \
 		-i sphinx/pycode/pgen2 -i sphinx/util/smartypants.py -i .ropeproject \
 		-i doc/_build -i ez_setup.py -i tests/path.py -i tests/coverage.py \
 		-i env -i .tox .
 
-clean: clean-pyc clean-patchfiles clean-backupfiles
+clean: clean-pyc clean-patchfiles clean-backupfiles clean-generated
 
 clean-pyc:
 	find . -name '*.pyc' -exec rm -f {} +
@@ -26,10 +26,13 @@ clean-backupfiles:
 	find . -name '*~' -exec rm -f {} +
 	find . -name '*.bak' -exec rm -f {} +
 
+clean-generated:
+	rm utils/*3.py*
+
 pylint:
 	@pylint --rcfile utils/pylintrc sphinx
 
-reindent:
+reindent: convert-utils
 	@$(PYTHON) utils/reindent.py -r -B .
 
 test: build
@@ -40,3 +43,6 @@ covertest: build
 
 build:
 	@$(PYTHON) setup.py build
+
+convert-utils:
+	@python3 utils/convert.py -i utils/convert.py utils/

utils/convert.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+# coding: utf-8
+"""
+    Converts files with 2to3
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Creates a Python 3 version of each file.
+
+    The Python3 version of a file foo.py will be called foo3.py.
+
+    :copyright: Copyright 2010 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+import os
+import sys
+from glob import iglob
+from optparse import OptionParser
+from shutil import copy
+from distutils.util import run_2to3
+
+def main(argv):
+    parser = OptionParser(usage='%prog [path]')
+    parser.add_option('-i', '--ignorepath', dest='ignored_paths',
+                      action='append', default=[])
+    options, args = parser.parse_args(argv)
+
+    ignored_paths = set(options.ignored_paths)
+
+    path = os.path.abspath(args[0]) if args else os.getcwd()
+    convertables = []
+    for filename in iglob(os.path.join(path, '*.py')):
+        if filename in ignored_paths:
+            continue
+        basename, ext = os.path.splitext(filename)
+        if basename.endswith('3'):
+            continue
+        filename3 = basename + '3' + ext
+        copy(filename, filename3)
+        convertables.append(filename3)
+    run_2to3(convertables)
+
+if __name__ == "__main__":
+    main(sys.argv[1:])