Fixes #1984: Hint None being valid for primary_domain.

sphinx/config.py

@@ -18,7 +18,7 @@ from six import PY3, iteritems, string_types, binary_type, integer_types
 from sphinx.errors import ConfigError
 from sphinx.locale import l_
 from sphinx.util.osutil import make_filename, cd
-from sphinx.util.pycompat import execfile_
+from sphinx.util.pycompat import execfile_, NoneType
 
 nonascii_re = re.compile(br'[\x80-\xff]')
 
@@ -74,7 +74,7 @@ class Config(object):
         rst_epilog = (None, 'env', [str]),
         rst_prolog = (None, 'env', [str]),
         trim_doctest_flags = (True, 'env'),
-        primary_domain = ('py', 'env'),
+        primary_domain = ('py', 'env', [NoneType]),
         needs_sphinx = (None, None, [str]),
         needs_extensions = ({}, None),
         nitpicky = (False, 'env'),

sphinx/util/pycompat.py

@@ -20,6 +20,8 @@ from itertools import product
 
 from six import PY3, text_type, exec_
 
+NoneType = type(None)
+
 # ------------------------------------------------------------------------------
 # Python 2/3 compatibility
 

tests/test_config.py

@@ -136,12 +136,18 @@ def test_config_eol(tmpdir):
         assert cfg.project == u'spam'
 
 
-@with_app(confoverrides={'master_doc': 123, 'language': 'foo'})
+@with_app(confoverrides={
+        'master_doc': 123,
+        'language': 'foo',
+        'primary_domain': None})
 def test_builtin_conf(app, status, warning):
-    assert_in('master_doc', warning.getvalue(),
+    warning = warning.getvalue()
+    assert_in('master_doc', warnings,
         'override on builtin "master_doc" should raise a type warning')
-    assert_not_in('language', warning.getvalue(), 'explicitly permitted '
+    assert_not_in('language', warnings, 'explicitly permitted '
         'override on builtin "language" should NOT raise a type warning')
+    assert_not_in('primary_domain', warnings, 'override to None on builtin '
+        '"primary_domain" should NOT raise a type warning')
 
 
 # See roots/test-config/conf.py.