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Currently, the order of set or frozenset elements when saved to bytecode is dependent on the random seed. This breaks reproducibility.
Example fail from an Arch Linux package: https://reproducible.archlinux.org/api/v0/builds/88454/diffoscope
Let's take an example file, `test_compile.py`
```python
s = {
 'aaa',
 'bbb',
 'ccc',
 'ddd',
 'eee',
}
```
$ PYTHONHASHSEED=0 python -m compileall --invalidation-mode checked-hash test_compile.py
$ mv __pycache__ __pycache__1
$ PYTHONHASHSEED=1 python -m compileall --invalidation-mode checked-hash test_compile.py
$ diff __pycache__/test_compile.cpython-39.pyc __pycache__1/test_compile.cpython-39.pyc
Binary files __pycache__/test_compile.cpython-39.pyc and __pycache__1/test_compile.cpython-39.pyc differ
$ diff <(xxd __pycache__/test_compile.cpython-39.pyc) <(xxd __pycache__1/test_compile.cpython-39.pyc)
5,6c5,6
< 00000040: 005a 0362 6262 5a03 6464 645a 0361 6161 .Z.bbbZ.dddZ.aaa
< 00000050: 5a03 6363 635a 0365 6565 4e29 01da 0173 Z.cccZ.eeeN)...s
---
> 00000040: 005a 0361 6161 5a03 6363 635a 0364 6464 .Z.aaaZ.cccZ.ddd
> 00000050: 5a03 6565 655a 0362 6262 4e29 01da 0173 Z.eeeZ.bbbN)...s
I believe the issue is in the marshall module. Particularly, this line[1]. My simple fix was to create a list from the set, sort it, and iterate over it instead.
[1] https://github.com/python/cpython/blob/00d7abd7ef588fc4ff0571c8579ab4aba8ada1c0/Python/marshal.c#L505