+# check_sphinx.m4 -- check for Sphinx Python package
+#
+# Copyright (C) 2015 - Philippe Proulx <pproulx@efficios.com>
+#
+# This file is free software; the Free Software Foundation gives
+# unlimited permission to copy and/or distribute it, with or without
+# modifications, as long as this notice is preserved.
+
+# Sphinx ships with a script named "sphinx-build", which is usually
+# installed in "/usr/bin". Unfortunately, this script uses
+# "/usr/bin/python" as its interpreter. Since "/usr/bin/python" can
+# be either Python 2 or Python 3, depending on the distribution, and
+# since we absolutely need the Python 3 Sphinx package for Babeltrace
+# because it needs to import our bindings for autodocumentation,
+# there's no way to tell if "sphinx-build" is actually using Python 2
+# or Python 3.
+#
+# This macro checks if the Sphinx package ("sphinx") is installed
+# and visible from the interpreter designated by the PYTHON variable.
+# It sets PYTHON_SPHINX_EXISTS to "yes" if Sphinx is found for the
+# given Python interpreter, otherwise "no".
+
+# AM_CHECK_PYTHON_SPHINX(PYTHON)
+# ---------------------------------------------------------------------------
+AC_DEFUN([AM_CHECK_PYTHON_SPHINX],
+ [prog="
+try:
+ import sphinx
+ print('yes')
+except ImportError:
+ print('no')"
+ PYTHON_SPHINX_EXISTS=`${$1} -c "$prog"`])