bpo-32415: Fix "error is already set" (#4999)

Yury Selivanov · web-flow · commit 719ccbca69b2 · 2017-12-23T16:29:26.000-05:00
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
@@ -2302,6 +2302,32 @@ class Future(futures._PyFuture):
         pass
 
 
+@unittest.skipUnless(hasattr(tasks, '_CTask'),
+                     'requires the C _asyncio module')
+class CTask_Future_Tests(test_utils.TestCase):
+
+    def test_foobar(self):
+        class Fut(asyncio.Future):
+            @property
+            def get_loop(self):
+                raise AttributeError
+
+        async def coro():
+            await fut
+            return 'spam'
+
+        self.loop = asyncio.new_event_loop()
+        try:
+            fut = Fut(loop=self.loop)
+            self.loop.call_later(0.1, fut.set_result(1))
+            task = asyncio.Task(coro(), loop=self.loop)
+            res = self.loop.run_until_complete(task)
+        finally:
+            self.loop.close()
+
+        self.assertEqual(res, 'spam')
+
+
 class BaseTaskIntrospectionTests:
     _register_task = None
     _unregister_task = None
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
@@ -203,6 +203,7 @@ get_future_loop(PyObject *fut)
         return res;
     }
 
+    PyErr_Clear();
     return _PyObject_GetAttrId(fut, &PyId__loop);
 }
 

Original file line number	Diff line number	Diff line change
`@@ -203,6 +203,7 @@ get_future_loop(PyObject *fut)`
`203`	`203`	`return res;`
`204`	`204`	`}`
`205`	`205`
	`206`	`+ PyErr_Clear();`
`206`	`207`	`return _PyObject_GetAttrId(fut, &PyId__loop);`
`207`	`208`	`}`
`208`	`209`