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GeezerVison is showing github.com — [3.15] gh-158445: Detect invalid UCS4 characters in debug mode (#158502) by vstinner · Pull Request #159524 · python/cpython

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@vstinner

@vstinner vstinner commented Oct 16, 2026 •
edited by bedevere-app Bot
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  • Issue: C API: Detect invalid UCS4 characters in debug mode #158445

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vstinner added 2 commits October 16, 2026 13:28
@vstinner
pythongh-158445: Detect invalid UCS4 characters in debug mode (python…
7c5f4eb 
…#158502)

In debug mode, PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND) and
PyUnicodeWriter_WriteUCS4() now raise a SystemError if a character is
not in range [U+0000; U+10ffff], instead of creating an invalid str
object.

In release mode, PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND)
raises a SystemError if the size is 1.

* In debug mode, unicode_char() no longer fails with an assertion
  error if the character is invalid. Instead, raise SystemError.
* Add tests on invalid UCS-4 characters.
* Add _testinternalcapi._Py_MAX_UNICODE.
* Add unicode_invalid_character() helper function.

(cherry picked from commit a14a4a6)
@vstinner
pythongh-158445: Skip invalid UCS-4 tests if Python is built with ass…
e0ba4e7 
…ertions (python#158604)

If Python is built in release mode with assertions,
PyUnicode_FromKindAndData() and PyUnicodeWriter_Finish() fail with an
assertion error on invalid characters.

(cherry picked from commit 35bdbca)
@vstinner
vstinner requested a review from ZeroIntensity as a code owner October 16, 2026 11:29
@vstinner vstinner added skip news needs backport to 3.14 bugs and security fixes labels Oct 16, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Oct 16, 2026
C API: Detect invalid UCS4 characters in debug mode #158445
Closed
@bedevere-app bedevere-app Bot added the awaiting core review label Oct 16, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Oct 16, 2026
gh-158445: Detect invalid UCS4 characters in debug mode #158502
Merged
@read-the-docs-community

read-the-docs-community Bot commented Oct 16, 2026

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Documentation build overview

📚 cpython-previews | 🛠️ Build #35190753 | 📁 Comparing e0ba4e7 against main (c7a1716)

  🔍 Preview build  

140 files changed · + 1 added · ± 134 modified · - 5 deleted

+ Added

  • library/asyncio-policy.html

± Modified

  • index.html
  • license.html
  • py-modindex.html
  • builtins/exceptions.html
  • builtins/functions.html
  • builtins/stdtypes.html
  • c-api/bytes.html
  • c-api/capsule.html
  • c-api/complex.html
  • c-api/coro.html
  • and 124 more...

- Deleted

  • deprecations/pending-removal-in-3.21.html
  • library/tkinter.dialogs.html
  • library/tkinter.fontchooser.html
  • library/tkinter.systray.html
  • whatsnew/3.16.html
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@vstinner

vstinner commented Oct 16, 2026

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The 3.14 backport will rely on #159525 (not merged yet).
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@vstinner

vstinner commented Oct 16, 2026

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"x86_64-apple-darwin/clang (Debug)" and "x86_64-apple-darwin/clang (Release)" failed on installing LLVM, make was interrupted after 60 minutes:

==> Installing dependencies for llvm@21: cmake, readline, sqlite, xz, pkgconf and [email protected]
==> Upgrading llvm@21 dependency: cmake (4.4.2 -> 4.4.4)
==> ./bootstrap --prefix=/usr/local/Cellar/cmake/4.4.4 --no-system-libs --parall
==> make
Error: The operation was canceled.
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@vstinner
vstinner merged commit 2c23505 into python:3.15 Oct 16, 2026
94 of 98 checks passed

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@vstinner
vstinner deleted the invalid_str15 branch October 16, 2026 14:47
@miss-islington-app

miss-islington-app Bot commented Oct 16, 2026

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Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖
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@bedevere-app bedevere-app Bot removed the awaiting core review label Oct 16, 2026
@miss-islington-app

miss-islington-app Bot commented Oct 16, 2026

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Sorry, @vstinner, I could not cleanly backport this to 3.14 due to a conflict.

Please backport manually with cherry_picker, see the devguide for more information.

cherry_picker 2c235059117a9b12d1650876d8413e80a734c31a 3.14
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@miss-islington-app miss-islington-app Bot assigned vstinner Oct 16, 2026
@bedevere-app

bedevere-app Bot commented Oct 16, 2026

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GH-159540 is a backport of this pull request to the 3.14 branch.
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@bedevere-app bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Oct 16, 2026
vstinner added a commit that referenced this pull request Oct 16, 2026
@vstinner
[3.14] gh-158445: Detect invalid UCS4 characters in debug mode (#158502…
09a7956 
…) (#159524) (#159540)

[3.15] gh-158445: Detect invalid UCS4 characters in debug mode (#158502) (#159524)

* gh-158445: Detect invalid UCS4 characters in debug mode (#158502)

In debug mode, PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND) and
PyUnicodeWriter_WriteUCS4() now raise a SystemError if a character is
not in range [U+0000; U+10ffff], instead of creating an invalid str
object.

In release mode, PyUnicode_FromKindAndData(PyUnicode_4BYTE_KIND)
raises a SystemError if the size is 1.

* In debug mode, unicode_char() no longer fails with an assertion
  error if the character is invalid. Instead, raise SystemError.
* Add tests on invalid UCS-4 characters.
* Add unicode_invalid_character() helper function.

(cherry picked from commit a14a4a6)

* gh-158445: Skip invalid UCS-4 tests if Python is built with assertions (#158604)

If Python is built in release mode with assertions,
PyUnicode_FromKindAndData() and PyUnicodeWriter_Finish() fail with an
assertion error on invalid characters.

(cherry picked from commit 35bdbca)
(cherry picked from commit 2c23505)
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