Description

chris-eibl

opened on Sep 12, 2026

Issue body actions

Bug report

Bug description:

Since version 22, clang-cl on Windows includes the repo url and commit hash in __clang_version__ like

22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)

versus just 21.1.4. before.

This results in sys.version being truncated

__clang_version__ is used in

cpython/PC/pyconfig.h

Line 161 in 7bfa97f

#define _Py_COMPILER ("[Clang " __clang_version__ "] 64 bit (AMD64) with MSC v." _Py_STRINGIZE(_MSC_VER) " CRT]")

exposed via getcompiler.c and then truncated in

cpython/Python/getversion.c

Lines 17 to 23 in 7bfa97f

	#ifdef Py_GIL_DISABLED
	const char *buildinfo_format = "%.80s free-threading build (%.80s) %.80s";
	#else
	const char *buildinfo_format = "%.80s (%.80s) %.80s";
	#endif
	PyOS_snprintf(version, sizeof(version), buildinfo_format,
	PY_VERSION, Py_GetBuildInfo(), Py_GetCompiler());

3.16.0a0 (heads/main:7bfa97f4dc, Sep 12 2026, 16:30:16) [Clang 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb45022 on win32

versus

3.16.0a0 (heads/main:7bfa97f4dc, Sep 12 2026, 16:32:39) [Clang 21.1.4 ] 64 bit (AMD64) with MSC v.1951 CRT] on win32

A lot of code depends on being able to parse the now missing 64 bit (AMD64) part (#145410, #154200, #154199, ...). Let's restore the old behaviour and fix the stray ] as well:

3.16.0a0 (heads/fix_clang_version:e1b196dfab, Sep 12 2026, 16:28:42) [Clang 22.1.3 64 bit (AMD64) with MSC v.1951 CRT] on win32

This also fixes the failing test_single_line_statement of @zware's AMD64 Windows Server 2025 Clang 3.x buildbot (and would also fix all the failing tests of the 3.14 and 3.15 Windows clang buildbots).

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• gh-157368: Fix clang-cl version in sys.version on Windows #157369
• [3.15] gh-157368: Fix clang-cl version in sys.version on Windows (GH-157369) #157565
• [3.14] gh-157368: Fix clang-cl version in sys.version on Windows (GH-157369) #157569
• [3.13] gh-157368: Fix clang-cl version in sys.version on Windows (GH-157369) #157606

Reacted by Stan Ulbrych

Activity

1. chris-eibl

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   OS-windows

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   OS-unsupported

   on Sep 12, 2026
2. github-project-automation

   added this to Unsupported platformson Sep 12, 2026
3. StanFromIreland

   removed

   OS-unsupported

   on Sep 12, 2026
4. StanFromIreland commented on Sep 12, 2026

   

   StanFromIreland

   on Sep 12, 2026

   Member

   More actions

   JYFI, if you're planning to fix this yourself I suggest you assign yourself, otherwise agents have a habit of sending PRs for such things...

   Reacted by Chris Eibl
5. chris-eibl

   self-assigned this

   on Sep 12, 2026
6. chris-eibl commented on Sep 12, 2026

   

   chris-eibl

   on Sep 12, 2026

   MemberAuthor

   More actions

   Hope I was faster :)

   Reacted by Stan Ulbrych and An Long
7. chris-eibl

   added

   OS-unsupported

   on Sep 12, 2026
8. chris-eibl commented on Sep 12, 2026

   

   chris-eibl

   on Sep 12, 2026

   MemberAuthor

   More actions

   Adding OS-unsupported again since @encukou ask me to do so for clang-cl issues in #154210 (comment).
9. chris-eibl

   moved this to In Progress in Unsupported platformson Sep 12, 2026
10. StanFromIreland commented on Sep 12, 2026

    

    StanFromIreland

    on Sep 12, 2026

    Member

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    Aargh, sorry, that makes sense!
11. zware

    added a commit that references this issue on Sep 13, 2026

    gh-157368: Fix clang-cl version in sys.version on Windows (GH-157369)

    0ba7be9
12. johnslavik

    added a commit that references this issue on Sep 14, 2026

    pythongh-157368: Fix clang-cl version in sys.version on Windows (pyth…

    6bb1710
13. zware

    added a commit that references this issue on Sep 15, 2026

    [3.14] gh-157368: Fix clang-cl version in sys.version on Windows (GH-…

    d6375c3
14. zware commented on Sep 15, 2026

    

    zware

    on Sep 15, 2026

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    Done other than 3.15, which I think will probably wait for 3.15.0 final.

    Reacted by Chris Eibl

    Reacted by Chris Eibl
15. zware

    closed this as completedon Sep 15, 2026
16. github-project-automation

    moved this from In Progress to Done in Unsupported platformson Sep 15, 2026
17. hugovk

    added a commit that references this issue on Sep 17, 2026

    [3.15] gh-157368: Fix clang-cl version in sys.version on Windows (GH-…

    5a1180c
18. vstinner commented on Oct 2, 2026

    

    vstinner

    on Oct 2, 2026

    Member

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    I wrote PR gh-158608 to allocate Py_GetVersion() on the heap memory, to no longer have fixed limits.

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