[methane]

Remove obsolete platform workarounds and configuration checks whose results are no longer used:

• Remaining IRIX workarounds: Remove IRIX-specific declarations, header handling, and macros from socket, select, termios, curses, posix, and integer-conversion code. IRIX support was removed in Python 3.7.
• Checks left behind by removed modules: Remove checks for shadow.h, getspent(), getspnam(), linux/soundcard.h, sys/soundcard.h, and sys/audioio.h. Their consumers were the removed spwd, ossaudiodev, and sunaudiodev modules.
• Checks left behind by bundled libmpdec: Remove the glibc _FORTIFY_SOURCE/memmove bug check, GCC ipa-pure-const bug check, and x64 inline-assembler check. Their consumers were removed with bundled libmpdec in 9eb3b14. Also remove the -O2 availability check used only by the glibc bug check.
• Unused function checks: Remove checks for ftime(), getwd(), tempnam(), tmpnam(), tmpnam_r(), sigrelse(), fseek64(), and ftell64(). Neither their configuration macros nor their cached results have remaining consumers.
• Pre-ANSI compiler checks: Remove checks for working const, signed char, and function prototypes, along with their compatibility macros. These features are guaranteed by CPython’s C11 requirement.
• Obsolete MSVC version conditions: Remove conditions for compiler versions older than the supported minimum, retaining the current implementations and non-MSVC alternatives. This covers Windows configuration, socket headers, secure CRT handling, and invalid-parameter handlers.
• Legacy BSD workarounds: Remove _XOPEN_SOURCE exceptions for OpenBSD 2.x–4.6 and NetBSD 1.5–1.6-era releases, and the pre-December-1997 NetBSD dynamic-loader workaround.
• Regenerate configure and pyconfig.h.in with Autoconf 2.72, and update the C API macro allowlist and platform headers accordingly.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @methane for commit 87fd74b 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F159513%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[Copilot]

🟢 Approval recommended

The removed checks have no remaining active consumers, and the compatibility cleanup preserves supported compiler and platform behavior.

No open issues 🎉

What changed in this PR

This PR simplifies CPython’s build configuration and portability code by removing unused feature checks and workarounds for unsupported platforms and compilers.

Changes:

• Remove configuration checks left behind by deleted modules, bundled libmpdec, and pre-ANSI compilers.
• Remove obsolete IRIX and BSD workarounds and simplify MSVC conditions while preserving supported paths.
• Synchronize generated configuration files, platform headers, and the C API macro allowlist.

File	Description
Tools/​build/​check_capi_macros_ignored.txt	Remove obsolete macros from the allowlist.
Python/​pylifecycle.c	Simplify the secure CRT signal-handling condition.
Python/​mystrtoul.c	Remove an IRIX-specific macro definition.
Python/​dynload_shlib.c	Remove the legacy NetBSD loader workaround.
pyconfig.h.in	Remove templates for deleted configuration checks.
PC/​pyconfig.h	Remove unused macros and obsolete MSVC branches.
PC/​invalid_parameter_handler.c	Remove the old MSVC guard and correct the header reference in a comment.
Modules/​timemodule.c	Simplify secure CRT conditions and clarify a comment.
Modules/​termios.c	Remove the IRIX control-character workaround.
Modules/​socketmodule.c	Remove IRIX workarounds and simplify MSVC header handling.
Modules/​selectmodule.c	Remove the IRIX-specific bzero declaration.
Modules/​posixmodule.c	Remove the IRIX-specific ctermid_r declaration.
Modules/​_cursesmodule.c	Remove IRIX-specific header and compatibility handling.
Include/​pyport.h	Remove an IRIX-specific macro definition.
Include/​pymacconfig.h	Remove the unused x64 assembler configuration macro.
Include/​internal/​pycore_fileutils.h	Simplify the MSVC invalid-parameter suppression condition.
configure.ac	Remove obsolete platform exceptions and unused checks.
configure	Reflect the configuration-check removals in generated output.

_{Review effort: Balanced}

[emmatyping]

I think we can probably leave this in? I presume people are still using Python on NetBSD and it is actively getting releases.

[methane]

The NetBSD < 199712 workaround targets ancient NetBSD versions and is no longer needed. <sys/param.h> is included only for the NetBSD macro, so the whole block can be removed.

[emmatyping]

Thanks for the PR, I love to see negative diffs! I had two tweaks to the changes but the rest LGTM.