When I pass pathlib.Path to asyncio.create_subprocess_exec I get:

TypeError: program arguments must be a bytes or text string, not PosixPath

It's not so good when subprocess accepts this kind of arguments without issues. So can you add support for this?

All we need is `program = os.fspath(program)` in base_events.py subprocess_exec() method.

Is anybody volunteered to make a patch (with test and docs update, sure)?

> All we need is `program = os.fspath(program)` in base_events.py subprocess_exec() method.

I don't think so. The arguments could be `pathlib.Path` too.

We can update the `isinstance(arg, (str, bytes))` check so the args pass on to `subprocess.Popen`. It will work in the POSIX part but there is an issue (issue33617, issue31961) in Windows part: subprocess.list2cmdline doesn't accept pathlib.Path.

Aha, I see. You are right.
Let's drop checks for cmd/program/args types but left to subprocess do these checks.
This approach avoiding complex checking/converting logic in asyncio itself and reduces code duplication.

New changeset 744c08a9c75a1a53b7a6521fcee3e7c513919ff9 by Miss Islington (bot) (依云) in branch 'master':
bpo-35246: fix support for path-like args in asyncio subprocess (GH-13628)
https://github.com/python/cpython/commit/744c08a9c75a1a53b7a6521fcee3e7c513919ff9