Support Cython-based async functions #550
Description
The title say it all, some projects re-implement their own iscoroutine function by looking for CO_COROUTINE and CO_ITERABLE_COROUTINE flags (for instance) to address this...
This is more of a CPython issue of course, but this currently means the coroutine generated by cython are not compatible with trio:
import trio
async def trio_main():
print('hello...')
await trio.sleep(1)
print(' world !')
def main():
trio.run(trio_main)
if __name__ == '__main__':
main()$ python cython_test.py
hello...
world !
$ cythonize -a -i cython_test.py
Compiling /home/emmanuel/projects/parsec-lrw/cython_test.py because it changed.
[1/1] Cythonizing /home/emmanuel/projects/parsec-lrw/cython_test.py
running build_ext
building 'cython_test' extension
creating /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home
creating /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home/emmanuel
creating /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home/emmanuel/projects
creating /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home/emmanuel/projects/parsec-lrw
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -fPIC -I/home/emmanuel/projects/cpython/build-install/include/python3.6m -c /home/emmanuel/projects/parsec-lrw/cython_test.c -o /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home/emmanuel/projects/parsec-lrw/cython_test.o
gcc -pthread -shared /home/emmanuel/projects/parsec-lrw/tmp0p_t5pyt/home/emmanuel/projects/parsec-lrw/cython_test.o -o /home/emmanuel/projects/parsec-lrw/cython_test.cpython-36m-x86_64-linux-gnu.so
$ python
Python 3.6.3 (v3.6.3:2c5fed8, Feb 6 2018, 17:05:14)
[GCC 5.4.1 20160904] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cython_test
>>> cython_test.main()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "cython_test.py", line 10, in cython_test.main
trio.run(trio_main)
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/trio/_core/_run.py", line 1238, in run
return result.unwrap()
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/trio/_core/_result.py", line 119, in unwrap
raise self.error
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/trio/_core/_run.py", line 1347, in run_impl
msg = task.context.run(task.coro.send, next_send)
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/contextvars/__init__.py", line 38, in run
return callable(*args, **kwargs)
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/trio/_core/_run.py", line 934, in init
async_fn, args, system_nursery, None
File "/home/emmanuel/projects/parsec-lrw/venv/lib/python3.6/site-packages/trio/_core/_run.py", line 805, in spawn_impl
.format(getattr(async_fn, "__qualname__", async_fn))
TypeError: trio expected an async function, but 'trio_main' appears to be synchronous
I didn't dig into CPython internal so my understanding on why inspect.iscoroutine != asyncio.iscoroutine on this is fairly limited, but I guess we should do something on our own to fix this anyway ;-)