GeezerVison

3.12.9 fails to build ctypes module on Cygwin if 3.12.8 is already installed as LIBFFI_LIBS
has "-L/usr/lib/../lib" and pull the installed version of "libpython3.12.dll.a" instead of the built one.

$ grep  -s -- "-L/usr/lib" config.status
"MODULE__CTYPES_LDFLAGS=-L/usr/lib/../lib -lffi -ldl\n"\
S["LIBFFI_LIBS"]="-L/usr/lib/../lib -lffi -ldl"

failed module:

gcc -shared -Wl,--enable-auto-image-base      Modules/_ctypes/_ctypes.o Modules/_ctypes/callbacks.o Modules/_ctypes/callproc.o Modules/_ctypes/stgdict.o Modules/_ctypes/cfield.o -L/usr/lib/../lib -lffi -ldl -L. -lpython3.12 -o Modules/_ctypes.cpython-312-x86_64-cygwin.dll
/usr/lib/gcc/x86_64-pc-cygwin/12/../../../../x86_64-pc-cygwin/bin/ld: Modules/_ctypes/callproc.o: in function `py_dl_close':
/usr/src/debug/python312-3.12.9-1/Modules/_ctypes/callproc.c:1573:(.text+0x5b8): undefined reference to `_PyErr_SetLocaleString'
/usr/lib/gcc/x86_64-pc-cygwin/12/../../../../x86_64-pc-cygwin/bin/ld: Modules/_ctypes/callproc.o: in function `py_dl_open':
/usr/src/debug/python312-3.12.9-1/Modules/_ctypes/callproc.c:1555:(.text+0x6f8): undefined reference to `_PyErr_SetLocaleString'
collect2: error: ld returned 1 exit status
make: *** [Makefile:3130: Modules/_ctypes.cpython-312-x86_64-cygwin.dll] Error 1

inverting the order of library search solves the issue

$ gcc -shared -Wl,--enable-auto-image-base Modules/_ctypes/_ctypes.o Modules/_ctypes/callbacks.o Modules/_ctypes/callproc.o Modules/_ctypes/stgdict.o Modules/_ctypes/cfield.o -L. -L/usr/lib/../lib -lffi -ldl -lpython3.12 -o Modules/_ctypes.cpython-312-x86_64-cygwin.dll



### CPython versions tested on:

3.12

### Operating systems tested on:

Other

Activity

matzeri
added
type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error
on Feb 21, 2025
skirpichev
added
buildThe build process and cross-buildThe build process and cross-build
on Feb 22, 2025
ZeroIntensity
added
topic-ctypes
on Feb 24, 2025
jbigdata-git commented on Aug 11, 2025
jbigdata-git
on Aug 11, 2025
More actions
Hi,

I've been struggling for some time with compiling version 3.12.

My environment:

$ uname -a
CYGWIN_NT-10.0-26100 Data31 3.6.4-1.x86_64 2025-07-15 07:55 UTC x86_64 Cygwin
$ gcc -v
gcc version 13.4.0 (GCC)
$ make -v
GNU Make 4.4.1

3.12 ZIP downloaded from GIT
-rwxr-xr-x 1 29927478 Aug 8 12:25 cpython-3.12.zip

Configure ends OK

configure: WARNING:
Platform "x86_64-pc-cygwin" with compiler "gcc" is not supported by the
CPython core team, see https://peps.python.org/pep-0011/ for more information.

Make, compile, complile, link… and

gcc -shared -Wl,--enable-auto-image-base Modules/_pickle.o -L/usr/local/lib/python3.12/config-3.12 -lpython3.12 -o Modules/_pickle.cpython-312.dll
/usr/lib/gcc/x86_64-pc-cygwin/13/../../../../x86_64-pc-cygwin/bin/ld: Modules/_pickle.o: in function whichmodule': ./Modules/_pickle.c:1988:(.text+0xdc7e): undefined reference to _PySys_GetRequiredAttr'
collect2: error: ld returned 1 exit status
make: *** [Makefile:2990: Modules/_pickle.cpython-312.dll] Error 1

According to me everything seems OK, the C program containing the _PySys_GetRequiredAttr method has been compiled, the symbols are in the library for the link...

$ nm Python/sysmodule.o | grep GetRequiredAttr
0000000000001e00 T _PySys_GetRequiredAttr
00000000000025a0 T _PySys_GetRequiredAttrString
$ nm libpython3.12.a | grep GetRequiredAttr
U _PySys_GetRequiredAttr
U _PySys_GetRequiredAttrString
U _PySys_GetRequiredAttrString
U _PySys_GetRequiredAttr
0000000000001e00 T _PySys_GetRequiredAttr
00000000000025a0 T _PySys_GetRequiredAttrString
U _PySys_GetRequiredAttr

And yet, no.
I tried many things, even, in despair, changing the compiler using MSVCS, vcpkg, etc., but no success.

$ gcc -shared Modules/_pickle.o -lpython3.12 -o Modules/_pickle.cpython-312.dll
/usr/lib/gcc/x86_64-pc-cygwin/13/../../../../x86_64-pc-cygwin/bin/ld: Modules/_pickle.o: in function whichmodule': /home/jbdat/50-AI/cpython-3.12/./Modules/_pickle.c:1988:(.text+0xdc7e): undefined reference to _PySys_GetRequiredAttr'
collect2: error: ld returned 1 exit status

Can someone help me?
encukou
added
OS-unsupported
on Aug 11, 2025
github-project-automation
added this to Unsupported platformson Aug 11, 2025
encukou commented on Aug 11, 2025
encukou
on Aug 11, 2025
Member
More actions
I'm afraid I don't have Cygwing available to investigate this, but: did you make clean (or the stronger git clean -fxd) to remove artifacts from any previous builds?
jbigdata-git commented on Aug 13, 2025
jbigdata-git
on Aug 13, 2025
More actions
A little rusty with the C language...
export LDFLAGS="-L." allows me to go to the next problem...

To investigate, I launched the compilation command which fails on Cygwin, on Linux... And it works

3.12, Cyqwin, command KO
$ uname -a
CYGWIN_NT-10.0-26100 Data31 3.6.4-1.x86_64 2025-07-15 07:55 UTC x86_64 Cygwin
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/16/lto-wrapper.exe
Target: x86_64-pc-cygwin
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.0 20250727 (experimental) (GCC)
$ gcc -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O3 -Wall -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I. -I./Include -c ./Modules/ossaudiodev.c -o Modules/ossaudiodev.o
In file included from ./Include/Python.h:44,
from ./Modules/ossaudiodev.c:25:
./Include/object.h:135:9: error: initializer element is not constant
135 | (type)
| ^

3.12, Linux, same command OK
$ uname -a
Linux Data31 6.6.87.2-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/13/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Supported LTO compression algorithms: zlib zstd
gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04)
$ gcc -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O3 -Wall -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I. -I./Include -c ./Modules/ossaudiodev.c -o Modules/ossaudiodev.o
$

I also noticed that other .c files that use Python.h (so the variadic macros that cause the error) compile OK. I reused this command for ossaudiodev.c KO.

If anyone knows how to align the planets to compile on Cygwin...
encukou commented on Feb 13, 2026
encukou
on Feb 13, 2026
Member
More actions
Ultimately, Cygwin is an unsupported platform precisely because we don't have the relevant experts around.

Unfortunately, this is not an actionable issue in this repo. Consider the discussion forum or a Cygwin-specific place instead.
Good luck!
encukou
closed this as not planned on Feb 13, 2026
github-project-automation
moved this to Done in Unsupported platformson Feb 13, 2026

Metadata

Assignees

No one assigned

Labels

OS-unsupportedbuildThe build process and cross-buildThe build process and cross-buildtopic-ctypestype-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

Projects

Unsupported platforms
Status
Done
Show more project fields

Milestone

No milestone

Relationships

None yet

Development

No branches or pull requests

Issue actions

You are visitor 01402503 — GeezerVison does not store the pages you look up.
Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required.

GeezerVison

Build failure of 3.12.9 on Cygwin #130423

Description

Bug report

Bug description:

Activity

jbigdata-git commented on Aug 11, 2025

My environment:

Configure ends OK

Make, compile, complile, link… and

encukou commented on Aug 11, 2025

jbigdata-git commented on Aug 13, 2025

encukou commented on Feb 13, 2026

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions