implement shortcuts for async generators in async-for loop

Cython/Utility/AsyncGen.c

@@ -19,6 +19,7 @@ static PyTypeObject *__pyx__PyAsyncGenAThrowType = 0;
 static PyTypeObject *__pyx_AsyncGenType = 0;
 #define __Pyx_AsyncGen_CheckExact(obj) (Py_TYPE(obj) == __pyx_AsyncGenType)
 
+static PyObject *__Pyx_AsyncGen_ANext(PyObject *o);
 
 static __pyx_CoroutineObject *__Pyx_AsyncGen_New(
             __pyx_coroutine_body_t body, PyObject *closure,
@@ -208,8 +209,9 @@ __Pyx_async_gen_init_finalizer(__pyx_AsyncGenObject *o)
 
 
 static PyObject *
-__Pyx_async_gen_anext(__pyx_AsyncGenObject *o)
+__Pyx_AsyncGen_ANext(PyObject *self)
 {
+    __pyx_AsyncGenObject *o = (__pyx_AsyncGenObject *)self;
     if (__Pyx_async_gen_init_finalizer(o)) {
         return NULL;
     }
@@ -286,7 +288,7 @@ static PyMethodDef __Pyx_async_gen_methods[] = {
 static PyAsyncMethods __Pyx_async_gen_as_async = {
     0,                                          /* am_await */
     PyObject_SelfIter,                          /* am_aiter */
-    (unaryfunc)__Pyx_async_gen_anext            /* am_anext */
+    (unaryfunc)__Pyx_AsyncGen_ANext             /* am_anext */
 };
 
 

Cython/Utility/Coroutine.c

@@ -170,8 +170,7 @@ static PyObject *__Pyx__Coroutine_GetAwaitableIter(PyObject *o); /*proto*/
 static CYTHON_INLINE PyObject *__Pyx_Coroutine_GetAwaitableIter(PyObject *o) {
 #ifdef __Pyx_Coroutine_USED
     if (__Pyx_Coroutine_CheckExact(o)) {
-        Py_INCREF(o);
-        return o;
+        return __Pyx_NewRef(o);
     }
 #endif
     return __Pyx__Coroutine_GetAwaitableIter(o);
@@ -257,11 +256,18 @@ static CYTHON_INLINE PyObject *__Pyx_Coroutine_AsyncIterNext(PyObject *o); /*pro
 //@requires: ObjectHandling.c::PyObjectCallMethod0
 
 static CYTHON_INLINE PyObject *__Pyx_Coroutine_GetAsyncIter(PyObject *obj) {
+#ifdef __Pyx_AsyncGen_USED
+    if (__Pyx_AsyncGen_CheckExact(obj)) {
+        return __Pyx_NewRef(obj);
+    }
+#endif
 #if CYTHON_USE_ASYNC_SLOTS
+    {
         __Pyx_PyAsyncMethodsStruct* am = __Pyx_PyType_AsAsync(obj);
         if (likely(am && am->am_aiter)) {
             return (*am->am_aiter)(obj);
         }
+    }
 #endif
 #if PY_VERSION_HEX < 0x030500B1
     {
@@ -282,12 +288,20 @@ static CYTHON_INLINE PyObject *__Pyx_Coroutine_GetAsyncIter(PyObject *obj) {
     return NULL;
 }
 
+
 static CYTHON_INLINE PyObject *__Pyx_Coroutine_AsyncIterNext(PyObject *obj) {
+#ifdef __Pyx_AsyncGen_USED
+    if (__Pyx_AsyncGen_CheckExact(obj)) {
+        return __Pyx_AsyncGen_ANext(obj);
+    }
+#endif
 #if CYTHON_USE_ASYNC_SLOTS
+    {
         __Pyx_PyAsyncMethodsStruct* am = __Pyx_PyType_AsAsync(obj);
         if (likely(am && am->am_anext)) {
             return (*am->am_anext)(obj);
         }
+    }
 #endif
 #if PY_VERSION_HEX < 0x030500B1
     {