SIM905 fix breaks `"".split(maxsplit=0)` and similar expressions

[dscorbett]

Summary

The fix for split-static-string (SIM905) changes the behavior of str.split with sep=None (the default) and maxsplit=0 if the string is empty or begins with white space. The output of split should not contain an empty string or a string beginning with white space. Similarly, the fix breaks str.rsplit if the string is empty or ends with white space.

$ cat >sim905.py <<'# EOF'
print("".split(maxsplit=0))
print(" ".split(maxsplit=0))
print(" x ".split(maxsplit=0))
print("".rsplit(maxsplit=0))
print(" ".rsplit(maxsplit=0))
print(" x ".rsplit(maxsplit=0))
# EOF

$ python sim905.py
[]
[]
['x ']
[]
[]
[' x']

$ ruff --isolated check sim905.py --select SIM905 --fix
Found 6 errors (6 fixed, 0 remaining).

$ python sim905.py
['']
[' ']
[' x ']
['']
[' ']
[' x ']

Version

ruff 0.11.9 (2370297 2025-05-09)