Remove the _create_cancelled_error() helper function.

cjerdonek · May 15, 2020 · May 7, 2020 · May 7, 2020 · May 7, 2020 · May 7, 2020
commit 22a54cc448747b7e6d0ee57b5c4cc93d2aead540
diff --git a/Lib/asyncio/futures.py b/Lib/asyncio/futures.py
@@ -175,7 +175,9 @@ def result(self):
         the future is done and has an exception set, this exception is raised.
         """
         if self._state == _CANCELLED:
-            raise _create_cancelled_error(self._cancel_message)
+            raise exceptions.CancelledError(
+                '' if self._cancel_message is None else self._cancel_message)
+
         if self._state != _FINISHED:
             raise exceptions.InvalidStateError('Result is not ready.')
         self.__log_traceback = False
@@ -192,7 +194,8 @@ def exception(self):
         InvalidStateError.
         """
         if self._state == _CANCELLED:
-            raise _create_cancelled_error(self._cancel_message)
+            raise exceptions.CancelledError(
+                '' if self._cancel_message is None else self._cancel_message)
         if self._state != _FINISHED:
             raise exceptions.InvalidStateError('Exception is not set.')
         self.__log_traceback = False
@@ -293,15 +296,6 @@ def _set_result_unless_cancelled(fut, result):
     fut.set_result(result)
 
 
-# This provides a nicer-looking traceback when no msg is passed, which
-# has been asyncio's default behavior.
-def _create_cancelled_error(msg=None):
-    if msg is None:
-        return exceptions.CancelledError()
-
-    return exceptions.CancelledError(msg)
-
-
 def _convert_future_exc(exc):
     exc_class = type(exc)
     if exc_class is concurrent.futures.CancelledError:

diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
@@ -270,7 +270,8 @@ def __step(self, exc=None):
                 f'_step(): already done: {self!r}, {exc!r}')
         if self._must_cancel:
             if not isinstance(exc, exceptions.CancelledError):
-                exc = futures._create_cancelled_error(self._cancel_message)
+                exc = exceptions.CancelledError(''
+                    if self._cancel_message is None else self._cancel_message)
             self._must_cancel = False
         coro = self._coro
         self._fut_waiter = None
@@ -778,7 +779,8 @@ def _done_callback(fut):
                 # Check if 'fut' is cancelled first, as
                 # 'fut.exception()' will *raise* a CancelledError
                 # instead of returning it.
-                exc = futures._create_cancelled_error(fut._cancel_message)
+                exc = exceptions.CancelledError(''
+                    if fut._cancel_message is None else fut._cancel_message)
                 outer.set_exception(exc)
                 return
             else:
@@ -797,7 +799,9 @@ def _done_callback(fut):
                     # Check if 'fut' is cancelled first, as
                     # 'fut.exception()' will *raise* a CancelledError
                     # instead of returning it.
-                    res = futures._create_cancelled_error(fut._cancel_message)
+                    res = exceptions.CancelledError(
+                        '' if fut._cancel_message is None else
+                        fut._cancel_message)
                 else:
                     res = fut.exception()
                     if res is None:
@@ -808,8 +812,9 @@ def _done_callback(fut):
                 # If gather is being cancelled we must propagate the
                 # cancellation regardless of *return_exceptions* argument.
                 # See issue 32684.
-                outer.set_exception(
-                    futures._create_cancelled_error(fut._cancel_message))
+                exc = exceptions.CancelledError(''
+                    if fut._cancel_message is None else fut._cancel_message)
+                outer.set_exception(exc)
             else:
                 outer.set_result(results)
 

diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
@@ -542,8 +542,8 @@ async def task():
     def test_cancel_with_message_then_future_result(self):
         # Test Future.result() after calling cancel() with a message.
         cases = [
-            ((), ()),
-            ((None,), ()),
+            ((), ('',)),
+            ((None,), ('',)),
             (('my message',), ('my message',)),
             # Non-string values should roundtrip.
             ((5,), (5,)),
@@ -572,8 +572,8 @@ async def coro():
     def test_cancel_with_message_then_future_exception(self):
         # Test Future.exception() after calling cancel() with a message.
         cases = [
-            ((), ()),
-            ((None,), ()),
+            ((), ('',)),
+            ((None,), ('',)),
             (('my message',), ('my message',)),
             # Non-string values should roundtrip.
             ((5,), (5,)),
@@ -2344,8 +2344,8 @@ def cancelling_callback(_):
 
     def test_cancel_gather_2(self):
         cases = [
-            ((), ()),
-            ((None,), ()),
+            ((), ('',)),
+            ((None,), ('',)),
             (('my message',), ('my message',)),
             # Non-string values should roundtrip.
             ((5,), (5,)),

diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
@@ -601,7 +601,9 @@ create_cancelled_error(PyObject *msg)
 {
     PyObject *exc;
     if (msg == NULL || msg == Py_None) {
-        exc = PyObject_CallNoArgs(asyncio_CancelledError);
+        msg = PyUnicode_FromString("");
+        exc = PyObject_CallOneArg(asyncio_CancelledError, msg);
+        Py_DECREF(msg);
     } else {
         exc = PyObject_CallOneArg(asyncio_CancelledError, msg);
     }