gh-118908: Limit exposed globals from internal imports and definitions on new REPL startup

[eugenetriguba]

Currently, we expose some of the internal imports and definitions on REPL startup in the new REPL.

% ./python.exe
Python 3.14.0a0 (heads/main:de19694cfb, May 25 2024, 07:36:35) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> dir()
['CAN_USE_PYREPL', '__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'interactive_console', 'os', 'sys']

This PR addresses that by moving the implementation of main into its own separate module and only importing in what is needed to get it running. Now, we see there is only interactive_console in addition to the dunder attributes shown in the global scope on startup.

% ./python.exe
Python 3.14.0a0 (heads/main:de19694cfb, May 25 2024, 07:36:35) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> dir()
['__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'interactive_console']

• Issue: New REPL exposes its internal imports/definitions to top-level environment #118908

[pablogsal]

Thanks for the PR @eugenetriguba but unfortunately I don't think this is the proper fix for this issue. The proper fix is to properly filter the namespace here:

cpython/Lib/_pyrepl/simple_interact.py

Line 122 in b407ad3

mainmodule = mainmodule or __main__

And to use a clean one when it makes sense (when not running with -i) or filtering the stuff we don't want.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[lysnikolaou]

Looks good! 🎉

Just a couple of comments.

[lysnikolaou]

Just one final comment and this is good to go! Thanks both!

[lysnikolaou]

LGTM!

[miss-islington-app]

Thanks @eugenetriguba for the PR, and @pablogsal for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-120362 is a backport of this pull request to the 3.13 branch.

[eugenetriguba]

@pablogsal Been a bit busy and was unable to get back to this, thank you for finishing it off and the feedback 🙂

[encukou]

Since this commit, the "AMD64 Debian PGO 3.x" buildbot has started reporting a runaway process, e.g. here:

1:17:07 load avg: 20.12 [453/478/1] test_pyrepl failed (env changed) (37.4 sec)
test_empty (test.test_pyrepl.test_input.KeymapTranslatorTests.test_empty) ... ok
test_push_character_key (test.test_pyrepl.test_input.KeymapTranslatorTests.test_push_character_key) ... ok
test_push_character_key_with_stack (test.test_pyrepl.test_input.KeymapTranslatorTests.test_push_character_key_with_stack) ... ok
[...]
test_exposed_globals_in_repl (test.test_pyrepl.test_pyrepl.TestMain.test_exposed_globals_in_repl) ... skipped 'pyrepl not available'
[...]

----------------------------------------------------------------------
Ran 116 tests in 35.634s

OK (skipped=2)
Warning -- reap_children() reaped child process 3457256

== Tests result: ENV CHANGED then ENV CHANGED ==