AsyncIO REPL does not respect $PYTHONSTARTUP on 3.12.3

[TahaAhmedRasheed]

Bug report

Bug description:

Script to reproduce:

#!/usr/bin/env bash
echo "Python version: $(python3 --version)"
cd $(mktemp -d)
echo "PWD is $PWD"
echo 'x=5' > startup.py
PYTHONSTARTUP="startup.py" python3
PYTHONSTARTUP="startup.py" python3 -m asyncio
cd - > /dev/null
echo "PWD is $PWD"

Current behaviour

$ ./repro.sh
Python version: Python 3.12.3
PWD is /tmp/tmp.lVtvc63MZq
Python 3.12.3 (main, Nov  6 2025, 13:44:16) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> x
5
>>> ^D
asyncio REPL 3.12.3 (main, Nov  6 2025, 13:44:16) [GCC 13.3.0] on linux
Use "await" directly instead of "asyncio.run()".
Type "help", "copyright", "credits" or "license" for more information.
>>> import asyncio
>>> x
Traceback (most recent call last):
  File "/usr/lib/python3.12/asyncio/__main__.py", line 58, in runcode
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/concurrent/futures/_base.py", line 456, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
  File "/usr/lib/python3.12/asyncio/__main__.py", line 34, in callback
    coro = func()
           ^^^^^^
  File "<console>", line 1, in <module>
NameError: name 'x' is not defined
>>> ^D
exiting asyncio REPL...
PWD is /tmp/tmp.1fcA8GVU2A
$

Expected behaviour
For x to be defined and set to 5, like in the regular non-asyncio REPL.

OS info

$ cat /etc/*-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=24.04
DISTRIB_CODENAME=noble
DISTRIB_DESCRIPTION="Ubuntu 24.04.2 LTS"
PRETTY_NAME="Ubuntu 24.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION="24.04.2 LTS (Noble Numbat)"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=noble
LOGO=ubuntu-logo

$ uname -a
Linux ROG 5.15.167.4-microsoft-standard-WSL2 #1 SMP Tue Nov 5 00:21:55 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

CPython versions tested on:

3.12

Operating systems tested on:

Linux

[zware]

Can you reproduce this with either 3.13 or 3.14? 3.12 is no longer receiving non-security fixes.

Note that with the new REPL in 3.13, there's an additional dimension to the testing matrix; we'll need to check with and without PYTHON_BASIC_REPL=1.

[dr-carlos]

Can you reproduce this with either 3.13 or 3.14? 3.12 is no longer receiving non-security fixes.

Note that with the new REPL in 3.13, there's an additional dimension to the testing matrix; we'll need to check with and without PYTHON_BASIC_REPL=1.

Doesn't seem to occur on Python 3.13/3.14 with or without PYTHON_BASIC_REPL=1 enabled.

[johnslavik]

Yes, the support for PYTHONSTARTUP in the asyncio REPL was added in GH-119433 (backported to 3.13, but not 3.12).

I think we can close this (cc @ZeroIntensity, @ambv).

[TahaAhmedRasheed]

@johnslavik Is there any way I could manually backport the fix to my existing Python installation?

[ZeroIntensity]

I assume you would need to backport all of _pyrepl. Why not just use 3.13?