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

Cython/Compiler/TypeSlots.py

@@ -813,6 +813,7 @@ PyAsyncMethods = (
     MethodSlot(unaryfunc, "am_await", "__await__"),
     MethodSlot(unaryfunc, "am_aiter", "__aiter__"),
     MethodSlot(unaryfunc, "am_anext", "__anext__"),
+    EmptySlot("am_send", ifdef="PY_VERSION_HEX >= 0x030A00A3"),
 )
 
 #------------------------------------------------------------------------------------------

Cython/Utility/AsyncGen.c

@@ -350,7 +350,10 @@ static PyMethodDef __Pyx_async_gen_methods[] = {
 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
 
@@ -593,7 +596,10 @@ static PyMethodDef __Pyx_async_gen_asend_methods[] = {
 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
 
@@ -1000,7 +1006,10 @@ static PyMethodDef __Pyx_async_gen_athrow_methods[] = {
 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

@@ -1647,6 +1647,9 @@ 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