Avoid C compiler warning about uninitialised "am_send" slots in Py3.10+.

Cython/Compiler/TypeSlots.py

@@ -1005,6 +1005,7 @@ class SlotTable(object):
             MethodSlot(unaryfunc, "am_await", "__await__", method_name_to_slot),
             MethodSlot(unaryfunc, "am_aiter", "__aiter__", method_name_to_slot),
             MethodSlot(unaryfunc, "am_anext", "__anext__", method_name_to_slot),
+            EmptySlot("am_send", ifdef="PY_VERSION_HEX >= 0x030A00A3"),
         )
 
         self.slot_table = (

Cython/Utility/AsyncGen.c

@@ -386,7 +386,10 @@ static PyType_Spec __pyx_AsyncGenType_spec = {
 static __Pyx_PyAsyncMethodsStruct __Pyx_async_gen_as_async = {
     0,                                          /* am_await */
     PyObject_SelfIter,                          /* am_aiter */
-    (unaryfunc)__Pyx_async_gen_anext             /* am_anext */
+    (unaryfunc)__Pyx_async_gen_anext,           /* am_anext */
+#if PY_VERSION_HEX >= 0x030A00A3
+    0, /*am_send*/
+#endif
 };
 #endif
 
@@ -661,7 +664,10 @@ static PyType_Spec __pyx__PyAsyncGenASendType_spec = {
 static __Pyx_PyAsyncMethodsStruct __Pyx_async_gen_asend_as_async = {
     PyObject_SelfIter,                          /* am_await */
     0,                                          /* am_aiter */
-    0                                           /* am_anext */
+    0,                                          /* am_anext */
+#if PY_VERSION_HEX >= 0x030A00A3
+    0, /*am_send*/
+#endif
 };
 #endif
 
@@ -1135,7 +1141,10 @@ static PyType_Spec __pyx__PyAsyncGenAThrowType_spec = {
 static __Pyx_PyAsyncMethodsStruct __Pyx_async_gen_athrow_as_async = {
     PyObject_SelfIter,                          /* am_await */
     0,                                          /* am_aiter */
-    0                                           /* am_anext */
+    0,                                          /* am_anext */
+#if PY_VERSION_HEX >= 0x030A00A3
+    0, /*am_send*/
+#endif
 };
 #endif
 

Cython/Utility/Coroutine.c

@@ -1735,6 +1735,9 @@ static __Pyx_PyAsyncMethodsStruct __pyx_Coroutine_as_async = {
     __Pyx_Coroutine_await, /*am_await*/
     0, /*am_aiter*/
     0, /*am_anext*/
+#if PY_VERSION_HEX >= 0x030A00A3
+    0, /*am_send*/
+#endif
 };
 #endif