Python 3.13 not support

[evertvorster]

Hi there!

Something got updated on my system, and I am unable to build master, as well as branches that I have been able to build before.

In all cases, the error message is this:

[ 10%] Building CXX object CMakeFiles/vegastrike_python.dir/src/python/config/python_utils.cpp.o
/mnt/int/system/aur/vegastrike-engine-git/src/Vega-Strike-Engine-Source/engine/src/python/config/python_utils.cpp: In function ‘const std::string GetPythonPath()’:
/mnt/int/system/aur/vegastrike-engine-git/src/Vega-Strike-Engine-Source/engine/src/python/config/python_utils.cpp:44:37: warning: ‘wchar_t* Py_GetPath()’ is deprecated [-Wdeprecated-declarations]
   44 |     wchar_t* w_path_ptr = Py_GetPath();
      |                           ~~~~~~~~~~^~
In file included from /usr/include/python3.13/Python.h:123,
                 from /usr/include/boost/python/detail/wrap_python.hpp:178,
                 from /usr/include/boost/python/detail/prefix.hpp:13,
                 from /usr/include/boost/python/args.hpp:8,
                 from /usr/include/boost/python.hpp:11,
                 from /mnt/int/system/aur/vegastrike-engine-git/src/Vega-Strike-Engine-Source/engine/src/python/config/python_utils.cpp:31:
/usr/include/python3.13/pylifecycle.h:46:43: note: declared here
   46 | Py_DEPRECATED(3.13) PyAPI_FUNC(wchar_t *) Py_GetPath(void);
      |                                           ^~~~~~~~~~
/mnt/int/system/aur/vegastrike-engine-git/src/Vega-Strike-Engine-Source/engine/src/python/config/python_utils.cpp: In function ‘PyObject* GetClassFromPython(std::string, std::string, std::string, std::string)’:
/mnt/int/system/aur/vegastrike-engine-git/src/Vega-Strike-Engine-Source/engine/src/python/config/python_utils.cpp:76:5: error: ‘Py_SetPath’ was not declared in this scope; did you mean ‘Py_GetPath’?
   76 |     Py_SetPath(python_path);
      |     ^~~~~~~~~~
      |     Py_GetPath
make[2]: *** [CMakeFiles/vegastrike_python.dir/build.make:79: CMakeFiles/vegastrike_python.dir/src/python/config/python_utils.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:224: CMakeFiles/vegastrike_python.dir/all] Error 2
make: *** [Makefile:156: all] Error 2
==> ERROR: A failure occurred in build().
    Aborting...

Normally I have makeflags -j32, so this failure got jumbled among all the other jobs that are running, but for this build single jobs were specified.

[evertvorster]

With a little Googling, it seems related to this commit:

python/cpython#105145

[BenjamenMeyer]

Looks like Py3.13 is broken for us.

[evertvorster]

Hi there...
I could change the way that vegastrike builds on Arch linux, and link to an older version of python, probably. However, this is an issue that needs fixing sooner or later, as other distributions of Linux will be following suit and also updating their version of Python to 3.13.

Keeping this in mind, is there any point in making a special package that uses an older python?

I guess it boils down to how long and involved this issue is to fix. I'm not a good enough coder to know, does anyone else have an idea?

[BenjamenMeyer]

@evertvorster agreed; though it may be a week or so before we get to it. You might be able to temporarily.

It shouldn't be a huge fix - just changing an API. It's just a matter of getting through several changes before we can probably get to it or get a PR merged. It may also be necessary to review the other APIs caught up in that deprecation too.

[stephengtuggy]

Okay, so I just looked at the code. This bug appears to be fairly limited in scope, with no more than 4 or 5 lines of code calling any of the deprecated or removed Python APIs from that deprecation. All of these lines of code were introduced in two of your commits, @royfalk , one from 2024-10-02 and the other from 2024-11-01. Filenames:

1. init.cpp
2. python_tests.cpp
3. python_utils.cpp
4. python_utils.h

The calls in question are Py_GetPath and Py_SetPath. No other deprecated APIs are involved here.

It looks like these two APIs can be replaced using https://docs.python.org/dev/c-api/init_config.html#init-isolated-conf and/or https://docs.python.org/dev/c-api/init_config.html#python-path-configuration

[stephengtuggy]

Please note, also, that this problem does not exist on the 0.9.x branch, since the Py_GetPath and Py_SetPath calls hadn't been introduced yet.

[evertvorster]

Not sure what changed, but git master compiles again.
There are a LOT of warnings, but it does compile.

[stephengtuggy]

Sweet! Yeah, I thought I had fixed it, sometime in the last week I believe. That's good to get confirmation that it is fixed.