```
Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7f008bf19667 in __interceptor_malloc (/lib64/libasan.so.6+0xb0667)
    #1 0x7f007a0bee4a in subprocess_fork_exec /home/heimes/dev/python/cpython/Modules/_posixsubprocess.c:774
    #2 0xe0305b in cfunction_call Objects/methodobject.c:546
```

Signed-off-by: Christian Heimes <christian@python.org>

* bpo-40791: Make compare_digest more constant-time.

The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization.

(This is change #1 from https://bugs.python.org/issue40791 .)

```
Direct leak of 8 byte(s) in 1 object(s) allocated from:
    GH-0 0x7f008bf19667 in __interceptor_malloc (/lib64/libasan.so.6+0xb0667)
    GH-1 0x7f007a0bee4a in subprocess_fork_exec /home/heimes/dev/python/cpython/Modules/_posixsubprocess.c:774
    GH-2 0xe0305b in cfunction_call Objects/methodobject.c:546
```

Signed-off-by: Christian Heimes <christian@python.org>
(cherry picked from commit 0d3350d)

Co-authored-by: Christian Heimes <christian@python.org>

* bpo-40791: Make compare_digest more constant-time.

The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization.

(This is change GH-1 from https://bugs.python.org/issue40791 .)
(cherry picked from commit 3172936)

Co-authored-by: Devin Jeanpierre <jeanpierreda@google.com>

* bpo-40791: Make compare_digest more constant-time.

The existing volatile `left`/`right` pointers guarantee that the reads will all occur, but does not guarantee that they will be _used_. So a compiler can still short-circuit the loop, saving e.g. the overhead of doing the xors and especially the overhead of the data dependency between `result` and the reads. That would change performance depending on where the first unequal byte occurs. This change removes that optimization.

(This is change GH-1 from https://bugs.python.org/issue40791 .)
(cherry picked from commit 3172936)

Co-authored-by: Devin Jeanpierre <jeanpierreda@google.com>

)

Fix test_gdb.test_pycfunction() for Python built with clang -Og.
Tolerate inlined functions in the gdb traceback.

When _testcapimodule.c is built by clang -Og, _null_to_none() is
inlined in meth_varargs() and so gdb returns _null_to_none() as
the frame #1. If it's not inlined, meth_varargs() is the frame #1.

…python#91466)

Fix an uninitialized bool in exception print context.
    
`struct exception_print_context.need_close` was uninitialized.
    
Found by oss-fuzz in a test case running under the undefined behavior sanitizer.
    
https://oss-fuzz.com/testcase-detail/6217746058182656
    
```
Python/pythonrun.c:1241:28: runtime error: load of value 253, which is not a valid value for type 'bool'
    #0 0xbf2203 in print_chained cpython3/Python/pythonrun.c:1241:28
    #1 0xbea4bb in print_exception_cause_and_context cpython3/Python/pythonrun.c:1320:19
    #2 0xbea4bb in print_exception_recursive cpython3/Python/pythonrun.c:1470:13
    #3 0xbe9e39 in _PyErr_Display cpython3/Python/pythonrun.c:1517:9
```
    
Pretty obvious what the ommission was upon code inspection.

…es (#1… (python#108688)

This reverts commit 08447b5.

Revert also _ctypes.c changes of the PyDict_ContainsString() change,
commit 6726626.

…ython#119498) (#1… (python#119905)

Revert "[3.12] pythongh-69214: Fix fcntl.ioctl() request type (python#119498) (python#119505)"

This reverts commit 078da88.

The change modified how negative values, like termios.TIOCSWINSZ, was
treated and is actually backward incompatible.

…er() (python#140574)

* pythongh-140281: Doc: Update free-threading how-to

* pythongh-140281: Doc: Update free-threading how-to

* Fix trailing whitespace

* doc fixing of the cpython fixes#84116

* Docs: Document help and aliases for argparse.add_parser() (pythongh-84116)

* Docs: Document help and aliases for argparse.add_parser() (pythongh-84116)

* Fix trailing whitespace

* Fix trailing whitespace

* Fix trailing whitespace

* Fix trailing whitespace

* Fix trailing whitespace

* Fix trailing whitespace

* Fix trailing errors

* Fix trailing errors and spaces

* Fix docutils formatting, NEWS ref, and trailing whitespace

* Docs: Update argparse.rst and add NEWS entry

* Delete Doc/howto/free-threading-python.rst

* Delete Misc/NEWS.d/next/Documentation/2025-10-25-00-49-43.gh-issue-140281.tuMQUe.rst

* adding the depreceated tag

* The error indexing was fixed

* Fix trailing whitespace

* Restore missing free-threading documentation

* fixing some minor error

* fixing some minor error part 2

* fixing some minor error part 3

* Fix NEWS entry format

* Final cleanup of NEWS entry format 2

* changes in the argparse.rst

* Remove unnecessary NEWS entry

* Fixing the issue as requested

* Added the Changes done before.

* done the changes

* done the changes#1

* Apply suggestion from @picnixz

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* Apply suggestion from @picnixz

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* Done the changes

* Done the new changes

* The versionadded is rectified

* Update Doc/library/argparse.rst

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

* Docs editing

* Docs fixing whitespace

* Docs rectifiying

* little bit rectification

* Indentation rectification

* Indentation rectification 1

* Apply suggestion from @picnixz

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* deprecated rectification

* Remove mistakenly added NEWS entry

* Update Doc/library/argparse.rst

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* changes #1

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* Update Doc/library/argparse.rst 2

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* removed useless thing

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* changed according to the request

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

* Updated the test part

---------

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>