[BUG] setuptools.depends:get_module_constant returns None on Python 3.13.0a1

[hroncok]

setuptools version

65.6.3.post20230109

Python version

3.13.0a1

OS

Fedora Linux

Additional environment information

This happens with later versions as well, but I reproduced from the main branch @ 2384d91

Description

The get_module_constant function from setuptools.depends returns None instead of the actual constant value on Python 3.13.0a1. This works fine on Python 3.12.0.

Expected behavior

The function should work the same on Python 3.12 and 3.13.

How to Reproduce

1. Create a simple Python file with a constant in it.
2. Run setuptools.depends:get_module_constant to retrieve it.

Output

$ cat foobar.py 
__version__ = "1"

$ venv3.12/bin/python -c 'import setuptools; print(setuptools.__version__); from setuptools.depends import get_module_constant; print(get_module_constant("foobar", "__version__"))'
65.6.3.post20230109
1

$ venv3.13/bin/python -c 'import setuptools; print(setuptools.__version__); from setuptools.depends import get_module_constant; print(get_module_constant("foobar", "__version__"))'
65.6.3.post20230109
None

[hroncok]

By debugging the setuptools code, I figured out the bytecode numbers must have changed:

$ venv3.13/bin/python -c 'import setuptools; print(setuptools.__version__); from setuptools.depends import get_module_constant; print(get_module_constant("foobar", "__version__"))'
65.6.3.post20230109
RESUME 149
LOAD_CONST 83
STORE_NAME 114
RETURN_CONST 103
None

$ venv3.12/bin/python -c 'import setuptools; print(setuptools.__version__); from setuptools.depends import get_module_constant; print(get_module_constant("foobar", "__version__"))'
65.6.3.post20230109
RESUME 151
LOAD_CONST 100
STORE_NAME 90
1

That's from

setuptools/setuptools/depends.py

Lines 145 to 147 in 2384d91

	STORE_NAME = 90
	STORE_GLOBAL = 97
	LOAD_CONST = 100

[encukou]

This should use dis.opmap rather than hardcoding the numeric values.
However, there is also no guarantee that e.g. LOAD_CONST will continue to be used for all loads of a constant -- CPython could, for example, add LOAD_CONST_STR that load string constants. So even dis.opmap isn't future-proof.

$ python3.13
>>> import dis
>>> dis.opmap['LOAD_CONST']
83