Fix ABCs in the MRO of gevent.local. Fixes #1201

CHANGES.rst

@@ -12,6 +12,9 @@
 - Update autoconf's config.guess and config.sub to the latest versions
   for c-ares and libev.
 
+- :class:`gevent.local.local` subclasses that mix-in ABCs can be instantiated.
+  Reported in :issue:`1201` by Bob Jordan.
+
 1.3b2 (2018-05-03)
 ==================
 

src/gevent/_local.pxd

@@ -102,7 +102,7 @@ cdef inline dict _local_get_dict(local self)
 @cython.locals(entry=_localimpl_dict_entry)
 cdef _local__copy_dict_from(local self, _localimpl impl, dict duplicate)
 
-@cython.locals(mro=list, base=type, gets=set, dels=set, set_or_del=set,
+@cython.locals(mro=list, gets=set, dels=set, set_or_del=set,
                type_self=type, type_attr=type,
                sets=set)
 cdef tuple _local_find_descriptors(local self)

src/gevent/local.py

@@ -538,8 +538,9 @@ def _local_find_descriptors(self):
         # return other class attributes. So we can't use getattr, and instead
         # walk up the dicts
         for base in mro:
-            if attr_name in base.__dict__:
-                attr = base.__dict__[attr_name]
+            bd = base.__dict__
+            if attr_name in bd:
+                attr = bd[attr_name]
                 break
         else:
             raise AttributeError(attr_name)

src/greentest/test__local.py

@@ -7,6 +7,10 @@ from gevent import monkey; monkey.patch_all()
 from threading import local
 from threading import Thread
 
+try:
+    from collections.abc import Mapping
+except ImportError:
+    from collections import Mapping
 
 class ReadProperty(object):
     """A property that can be overridden"""
@@ -68,6 +72,18 @@ class WithGetattr(local):
             return 42
         return super(WithGetattr, self).__getattr__(name)
 
+class LocalWithABC(local, Mapping):
+
+    def __getitem__(self, name):
+        return self.d[name]
+
+    def __iter__(self):
+        return iter(self.d)
+
+    def __len__(self):
+        return len(self.d)
+
+
 class TestGeventLocal(greentest.TestCase):
     # pylint:disable=attribute-defined-outside-init,blacklisted-name
 
@@ -325,6 +341,17 @@ class TestGeventLocal(greentest.TestCase):
         self.assertEqual(results,
                          [((MyLocal, id(x)), {'foo': 42})])
 
+    def test_local_with_abc(self):
+        # an ABC (or generally any non-exact-type) in the MRO doesn't
+        # break things. See https://github.com/gevent/gevent/issues/1201
+
+        x = LocalWithABC()
+        x.d = {'a': 1}
+        self.assertEqual({'a': 1}, x.d)
+        # The ABC part works
+        self.assertIn('a', x.d)
+        self.assertEqual(['a'], list(x.keys()))
+
 try:
     from zope import interface
 except ImportError: