gh-118934: Make PyEval_GetLocals return borrowed reference

[gaogaotiantian]

Per discussion with @markshannon in Pittsburgh, we simulate what we did pre-PEP667. We store the locals dict in frame->f_locals so that we can return a borrowed reference. The frame->f_locals will be cleared when the frame is released. This way we can keep the behavior of PyEval_GetLocals().

• Issue: PyEval_GetLocals() leaks locals #118934

[gaogaotiantian]

Just realized this will overwrite f_locals when it's called inside a comprehension of a non-optimized scope. We might have to use a new member in FrameObject to store this.

[colesbury]

A few formatting suggestions and a question about the return value

[ncoghlan]

@gaogaotiantian I merged the suggestion that reverts back to the Python 3.12 semantics, so we can get a CI run on that version of the refleak fix.

[ncoghlan]

@gaogaotiantian CI is happy with going back to the Python 3.12 behaviour, so if you're happy I think this is good to merge for the final beta.

[miss-islington-app]

Thanks @gaogaotiantian for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-121869 is a backport of this pull request to the 3.13 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora Clang Installed 3.13 has failed when building commit 233ed46.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#builders/1392/builds/214) and take a look at the build logs.
4. Check if the failure is related to this commit (233ed46) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#builders/1392/builds/214

Failed tests:

• test_pyrepl

Failed subtests:

• test_inspect_keeps_globals_from_inspected_file - test.test_pyrepl.test_pyrepl.TestMain.test_inspect_keeps_globals_from_inspected_file
• test_inspect_keeps_globals_from_inspected_module - test.test_pyrepl.test_pyrepl.TestMain.test_inspect_keeps_globals_from_inspected_module

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.clang-installed/build/target/lib/python3.13/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: FOO= not found in output


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.clang-installed/build/target/lib/python3.13/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: __name__= not found in output


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.clang-installed/build/target/lib/python3.13/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: __package__= not found in output

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x Fedora LTO + PGO 3.13 has failed when building commit 233ed46.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#builders/1511/builds/215) and take a look at the build logs.
4. Check if the failure is related to this commit (233ed46) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#builders/1511/builds/215

Failed tests:

• test_pyrepl

Failed subtests:

• test_inspect_keeps_globals_from_inspected_module - test.test_pyrepl.test_pyrepl.TestMain.test_inspect_keeps_globals_from_inspected_module

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.lto-pgo/build/Lib/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: __package__= not found in output


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.lto-pgo/build/Lib/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: __file__= not found in output


Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.13.edelsohn-fedora-z.lto-pgo/build/Lib/test/test_pyrepl/test_pyrepl.py", line 995, in _run_repl_globals_test
    self.fail(f"{var}= not found in output")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: FOO= not found in output