make internal marker types awaitable in older Python versions

Cython/Utility/AsyncGen.c

@@ -113,6 +113,9 @@ PyDoc_STRVAR(__Pyx_async_gen_throw_doc,
 "throw(typ[,val[,tb]]) -> raise exception in generator,\n\
 return next yielded value or raise StopIteration.");
 
+PyDoc_STRVAR(__Pyx_async_gen_await_doc,
+"__await__() -> return a representation that can be passed into the 'await' expression.");
+
 // COPY STARTS HERE:
 
 static PyObject *__Pyx_async_gen_asend_new(__pyx_PyAsyncGenObject *, PyObject *);
@@ -535,6 +538,7 @@ static PyMethodDef __Pyx_async_gen_asend_methods[] = {
     {"send", (PyCFunction)__Pyx_async_gen_asend_send, METH_O, __Pyx_async_gen_send_doc},
     {"throw", (PyCFunction)__Pyx_async_gen_asend_throw, METH_VARARGS, __Pyx_async_gen_throw_doc},
     {"close", (PyCFunction)__Pyx_async_gen_asend_close, METH_NOARGS, __Pyx_async_gen_close_doc},
+    {"__await__", (PyCFunction)PyObject_SelfIter, METH_NOARGS, __Pyx_async_gen_await_doc},
     {0, 0, 0, 0}        /* Sentinel */
 };
 
@@ -921,6 +925,7 @@ static PyMethodDef __Pyx_async_gen_athrow_methods[] = {
     {"send", (PyCFunction)__Pyx_async_gen_athrow_send, METH_O, __Pyx_async_gen_send_doc},
     {"throw", (PyCFunction)__Pyx_async_gen_athrow_throw, METH_VARARGS, __Pyx_async_gen_throw_doc},
     {"close", (PyCFunction)__Pyx_async_gen_athrow_close, METH_NOARGS, __Pyx_async_gen_close_doc},
+    {"__await__", (PyCFunction)PyObject_SelfIter, METH_NOARGS, __Pyx_async_gen_await_doc},
     {0, 0, 0, 0}        /* Sentinel */
 };
 

tests/run/test_asyncgen.py

@@ -33,6 +33,19 @@ else:
         return c
 
 
+try:
+    from types import coroutine as types_coroutine
+except ImportError:
+    def types_coroutine(f):
+        return f
+
+try:
+    from inspect import isawaitable as inspect_isawaitable
+except ImportError:
+    def inspect_isawaitable(o):
+        return hasattr(o, '__await__')
+
+
 # compiled exec()
 def exec(code_string, l, g):
     from Cython.Compiler.Errors import CompileError
@@ -57,7 +70,7 @@ class AwaitException(Exception):
     pass
 
 
-@types.coroutine
+@types_coroutine
 def awaitable(*, throw=False):
     if throw:
         yield ('throw',)
@@ -373,7 +386,7 @@ class AsyncGenTest(unittest.TestCase):
         self.assertFalse(g.ag_running)
         #self.assertIsInstance(g.ag_code, types.CodeType)
 
-        self.assertTrue(inspect.isawaitable(g.aclose()))
+        self.assertTrue(inspect_isawaitable(g.aclose()))
 
 
 @requires_asyncio