gh-158948: Add auto-generated Module/getbuildinfo.h

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Merge Python/getcompiler.c, Python/getcopyright.c, Python/getplatform.c and Python/getversion.c into
Modules/getbuildinfo.c.

Add Tools/build/generate_getbuildinfo.py to auto-generate a new Module/getbuildinfo.h header file which contains build information strings.

• Issue: Rework Modules/getbuildinfo.c to build strings at build time, instead of runtime #158948

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This PR is a draft. I didn't investigate Windows support yet. I didn't try cross-compilation, it may break.

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This change may fix the regression described by @itamaro: #158608 (comment).

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Tools/build/generate_getbuildinfo.py the SOURCE_DATE_EPOCH environment variable for reproducible build: https://reproducible-builds.org/specs/source-date-epoch/. If it's set, use it for the date and time.

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Ok, I fixed the out-of-tree build (used by the Ubuntu CI for example).

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Example of auto-generated Modules/getbuildinfo.h header file:

// Header file auto-generated by Tools/build/generate_getbuildinfo.py

#define DATE "Oct  7 2026"
#define TIME "05:35:34"
#define COMPILER "[GCC 16.2.1 20260819 (Red Hat 16.2.1-2)]"

#define PLATFORM "linux"

#define GITBRANCH "getbuildinfo"
#define GITTAG "heads/getbuildinfo"
#define GITVERSION "22d1a6b7c1e"
#define GIT_IDENTIFIER "heads/getbuildinfo"

#define BUILDINFO "heads/getbuildinfo:22d1a6b7c1e, Oct  7 2026, 05:35:34"
#define GET_VERSION "3.16.0a0 (heads/getbuildinfo:22d1a6b7c1e, Oct  7 2026, 05:35:34) [GCC 16.2.1 20260819 (Red Hat 16.2.1-2)]"

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Ah, the "WASI / build and test" job does cross-compile! Running the Programs/_getcompiler program to get the compiler version fails with Exec format error.

/home/runner/work/cpython/cpython/cross-build/aarch64-unknown-linux-gnu/python ../../Tools/build/generate_getbuildinfo.py Modules/getbuildinfo.h \
		"wasi" \
		`LC_ALL=C git --git-dir ../../.git rev-parse --short HEAD` \
		`LC_ALL=C git --git-dir ../../.git describe --all --always --dirty` \
		`LC_ALL=C git --git-dir ../../.git name-rev --name-only HEAD` \
		"`Programs/_getcompiler`"
(...)
/bin/sh: 1: Programs/_getcompiler: Exec format error

Later, running test.pythinfo fails on collect_platform() because sys.version lacks the compiler:

ERROR: collect_platform() failed
Traceback (most recent call last):
  File "/Lib/test/pythoninfo.py", line 1418, in collect_info
    collect_func(info_add)
    ~~~~~~~~~~~~^^^^^^^^^^
  File "/Lib/test/pythoninfo.py", line 185, in collect_platform
    platform.python_implementation())
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/Lib/platform.py", line 1199, in python_implementation
    return _sys_version()[0]
           ~~~~~~~~~~~~^^
  File "/Lib/platform.py", line 1159, in _sys_version
    raise ValueError(
        'failed to parse CPython sys.version: %s' %
        repr(sys_version))
ValueError: failed to parse CPython sys.version: '3.16.0a0 (remotes/pull/158951/merge-dirty:00e222b, Oct  7 2026, 03:37:58) '

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With the help of @zware, I managed to update the PCbuild project, to build Programs_getcompiler.c and generate Modules\getbuildinfo.h on Windows.

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Aha, test_freeze_simple_script() of test_tools fails on Ubuntu / build and test (ubuntu-26.04-arm) with:

LC_ALL=C sed -e 's,\$(\([A-Za-z0-9_]*\)),\$\{\1\},g' < Misc/python-config.sh >python-config
python3.14 /tmp/test_python_0l4z8_yx/tmpt900bnty/cpython/Tools/build/generate_getbuildinfo.py Modules/getbuildinfo.h \
		"linux" \
		`LC_ALL=C ` \
		`LC_ALL=C ` \
		`LC_ALL=C ` \
		"`Programs/_getcompiler || echo COMPILER`" \
		use_pyconfig
usage: generate_getbuildinfo.py OUTPUT PLATFORM GITVERSION GITTAG GITBRANCH COMPILER GIL_ENABLED
make[1]: Leaving directory '/tmp/test_python_0l4z8_yx/tmpt900bnty/python-build'

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Aha, test_freeze_simple_script() of test_tools fails on Ubuntu / build and test (ubuntu-26.04-arm)

It's just missing quotes: I fixed it.

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Cool! The change now builds successfully on all GitHub Action jobs! I checked sys.version:

• Windows / Build and test (x64, tail-call): CPython 3.16.0a0 (remotes/pull/158951/merge:1c30427, Oct 7 2026, 22:57:35) [MSC v.1951 32 bit (Intel)]
• macOS / build and test (macos-26): CPython 3.16.0a0 (remotes/pull/158951/merge:1c30427, Oct 7 2026, 22:58:53) [Clang 21.0.0 (clang-2100.1.1.101)]
• macOS (free-threading) / build and test (macos-26): CPython 3.16.0a0 free-threading build (remotes/pull/158951/merge:1c30427, Oct 7 2026, 23:00:13) [Clang 21.0.0 (clang-2100.1.1.101)]
• Ubuntu / build and test (ubuntu-26.04): CPython 3.16.0a0 (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 23:03:04) [GCC 15.2.0]
• Ubuntu (free-threading) / build and test (ubuntu-26.04-arm): CPython 3.16.0a0 free-threading build (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 22:58:15) [GCC 15.2.0]
• Android (x86_64): CPython 3.16.0a0 (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 23:00:19) [Android (13691557, +pgo, +bolt, +lto, +mlgo, based on r522817d) clang version 18.0.4 (https://android.googlesource.com/toolchain/llvm-project d8003a456d14a3deb8054cdaa529ffbf02d9b262)]
• iOS: CPython 3.16.0a0 (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 23:01:08) [Apple clang version 21.0.0 (clang-2100.1.1.101)]
• Emscripten / build and test: CPython 3.16.0a0 (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 22:53:20) [Clang 24.0.0git (https:/github.com/llvm/llvm-project a06d9165905ce89b5ffef2bbb84c886d60a9b8bf)]
• WASI / build and test: CPython 3.16.0a0 (remotes/pull/158951/merge-dirty:1c30427, Oct 7 2026, 22:58:12) [GCC 15.2.0]
• Cross build Linux: sys.version: 3.16.0a0 (remotes/pull/158951/merge:1c30427, Oct 7 2026, 22:59:42) [GCC 15.2.0]

Some Clang versions are quite verbose/long. I will update the PR to strip the URL.