gh-135763: Argument Clinic: Implement allow_negative for ssize_t #138150

wiomoc · 2025-08-25T23:28:14Z

Issue: Add a Clinic Convert for positive-only Py_ssize_t (but not size_t) #135763

picnixz

Please revert all changes that are not tests. Do not use it yet. In addition, consider expanding the tests in test_clinic.py if possible.

Python/modsupport.c

bedevere-app · 2025-08-26T09:22:26Z

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.

wiomoc · 2025-08-26T15:25:20Z

I have made the requested changes; please review again

I am going to raise a follow-up issue for migrating the existing manual bound checks, after this PR landed

bedevere-app · 2025-08-26T15:25:25Z

Thanks for making the requested changes!

@picnixz: please review the changes made to this pull request.

Include/internal/pycore_abstract.h

picnixz · 2025-08-30T11:03:40Z

Misc/NEWS.d/next/Library/2025-08-26-09-07-02.gh-issue-135763.DVpGUB.rst

@@ -0,0 +1,2 @@
+Add ``allow_negative`` flag to ``Py_ssize_t`` Argument Clinic converter, to


AC is unfortunately an internal tool so I don't think we should document it. However, what could be interesting is whether we want to expose a new parsing character for positive Py_ssize_t values. For now, https://docs.python.org/3/c-api/arg.html#numbers only documents n for Py_ssize_t but maybe having something for Py_ssize_t >= 0 would make sense (I don't know, so for now, don't change anything).

AC is unfortunately an internal tool so I don't think we should document it.

There are already entries regarding arg clinic in the changelog 1, therefore I think it's plausible to keep the entry. I moved it to tools/demos however - should be a better fit.

Whether we want to expose a new parsing character for positive Py_ssize_t values.

I wonder why not providing a format unit for conversion to size_t directly.
The only advantage is see with Py_ssize_t(allow_negative) in comparison to size_t is the fact that you could provide a negative value e.g. -1 default value as undefined / None sentinel.

I agree no NEWS entry is needed, but @wiomoc could create a PR for the devguide after this is merged, which is where we document AC.

I wonder why not providing a format unit for conversion to size_t directly.

Because we use ssize_t for most internal sizes in Python as we need to indicate when a conversion failed with value = -1 && PyErr_Occurred() (I think).

The only advantage is see with Py_ssize_t(allow_negative) in comparison to size_t is the fact that you could provide a negative value e.g. -1 default value as undefined / None sentinel.

Unfortunately, internally, most structures use ssize_t for sizes and not size_t, so we could have overflows here (that is, we pass a value that fits on a size_t but not on a ssize_t). See Py_buffer for instance.

Thanks for the explanation. Now I can make sense of it. I'll create an issue for adding N as the format unit for Py_ssize_t >= 0.

Python/modsupport.c

Tools/clinic/libclinic/converters.py

Lib/test/clinic.test.c

Lib/test/test_clinic.py

wiomoc · 2025-08-31T18:10:15Z

I have made the requested changes; please review again

Lib/test/clinic.test.c

Modules/_testclinic.c

Python/modsupport.c

Lib/test/clinic.test.c

changes made

Python/modsupport.c

bedevere-app · 2025-09-01T00:16:51Z

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.

changes made

bedevere-bot · 2025-09-01T23:10:48Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot s390x RHEL9 Refleaks 3.x (tier-3) has failed when building commit 47bc10e.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1589/builds/2061) and take a look at the build logs.
Check if the failure is related to this commit (47bc10e) or if it is a false positive.
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/1589/builds/2061

Failed tests:

test.test_multiprocessing_fork.test_processes

Failed subtests:

test_interrupt - test.test_multiprocessing_fork.test_processes.WithProcessesTestProcess.test_interrupt

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 596, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 577, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 573, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-3' pid=281260 parent=281256 started daemon>


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 524, in _sleep_some_event
    time.sleep(100)
    ~~~~~~~~~~^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/libregrtest/setup.py", line 83, in _test_audit_hook
    def _test_audit_hook(name, args):
    
KeyboardInterrupt
k


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 524, in _sleep_some_event
    time.sleep(100)
    ~~~~~~~~~~^^^^^
KeyboardInterrupt
k


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 596, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 577, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-rhel9-s390x.refleak/build/Lib/test/_test_multiprocessing.py", line 573, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-539' pid=208855 parent=200492 started daemon>

bedevere-bot · 2025-09-01T23:30:09Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Fedora Stable Refleaks 3.x (tier-1) has failed when building commit 47bc10e.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/320/builds/2966) and take a look at the build logs.
Check if the failure is related to this commit (47bc10e) or if it is a false positive.
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/320/builds/2966

Failed tests:

test.test_multiprocessing_fork.test_processes

Failed subtests:

test_interrupt - test.test_multiprocessing_fork.test_processes.WithProcessesTestProcess.test_interrupt

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 596, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 577, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 573, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-542' pid=2609465 parent=2601899 started daemon>


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 524, in _sleep_some_event
    time.sleep(100)
    ~~~~~~~~~~^^^^^
KeyboardInterrupt
k


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 596, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 577, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 250, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-fedora-stable-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 573, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-5' pid=2718849 parent=2718843 started daemon>

…ython#138150) Co-authored-by: Adam Turner <[email protected]>

bedevere-app bot mentioned this pull request Aug 25, 2025

Add a Clinic Convert for positive-only Py_ssize_t (but not size_t) #135763

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wiomoc force-pushed the gh-135763-clinic_allow_negative branch 3 times, most recently from 42f8e13 to 4ff6d71 Compare August 25, 2025 23:58

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wiomoc force-pushed the gh-135763-clinic_allow_negative branch from a36d270 to 119ccf3 Compare August 26, 2025 15:15

pythongh-135763: Argument Clinic: Impl allow_negative for ssize_t

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wiomoc and others added 4 commits August 31, 2025 23:44

add py_default test

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change wording to argument must be at least 0

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PyArg_Parse: Provide N as new format unit for non negative Py_ssize_t #138361

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AA-Turner merged commit 47bc10e into python:main Sep 1, 2025
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lkollar pushed a commit to lkollar/cpython that referenced this pull request Sep 9, 2025

pythongh-135763: AC: Implement allow_negative for Py_ssize_t (p…

08f73fa

…ython#138150) Co-authored-by: Adam Turner <[email protected]>

		@@ -0,0 +1,2 @@
		Add ``allow_negative`` flag to ``Py_ssize_t`` Argument Clinic converter, to

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