gh-154695: Fix Task(eager_start=True) with no explicit loop

Author: deadlovelll

Lib/test/test_asyncio/test_tasks.py

@@ -2733,6 +2733,18 @@ async def main():
             self.assertEqual(name, "example")
             await t
 
+    def test_eager_start_true_no_loop(self):
+        # gh-154695: eager_start must use the resolved loop, not loop=None.
+        async def asyncfn():
+            return 42
+
+        async def main():
+            t = self.__class__.Task(asyncfn(), eager_start=True)
+            self.assertTrue(t.done())
+            self.assertEqual(await t, 42)
+
+        asyncio.run(main(), loop_factory=asyncio.EventLoop)
+
     def test_eager_start_false(self):
         name = None
 

Misc/NEWS.d/next/Core_and_Builtins/2026-07-25-17-35-14.gh-issue-154695.aQWLLv.rst

@@ -0,0 +1,2 @@
+Fix :class:`asyncio.Task` raising :exc:`AttributeError` when created with
+``eager_start=True`` and no explicit *loop* argument.

Modules/_asynciomodule.c

@@ -2364,7 +2364,9 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop,
     _PyObject_SetMaybeWeakref((PyObject *)self);
 #endif
     if (eager_start) {
-        PyObject *res = PyObject_CallMethodNoArgs(loop, &_Py_ID(is_running));
+        // gh-154695: loop may be None here, future_init() resolved it into task_loop.
+        PyObject *res = PyObject_CallMethodNoArgs(self->task_loop,
+                                                  &_Py_ID(is_running));
         if (res == NULL) {
             return -1;
         }