PERF401 fix should parenthesize generator expressions

[dscorbett]

Summary

The fix for manual-list-comprehension (PERF401) changes the program’s behavior when the argument to append is an unparenthesized generator expression. It should parenthesize the argument. Example:

$ cat >perf401.py <<'# EOF'
i = "xyz"
result = []
for i in range(3):
   result.append(x for x in [i])
print(list(map(list, result)))
# EOF

$ python perf401.py
[[0], [1], [2]]

$ ruff --isolated check perf401.py --select PERF401 --preview --unsafe-fixes --fix
Found 1 error (1 fixed, 0 remaining).

$ cat perf401.py
i = "xyz"
result = [x for x in [i] for i in range(3)]
print(list(map(list, result)))

$ python perf401.py
[['x', 'y', 'z'], ['x', 'y', 'z'], ['x', 'y', 'z']]

Version

ruff 0.12.2 (9bee837 2025-07-03)

[CodeMan62]

i am taking this will fix it