[`flake8-bugbear`] Include certain guaranteed-mutable expressions: tuples, generators, and assignment expressions (`B006`) (#20024)
## Summary
Resolves #20004
The implementation now supports guaranteed-mutable expressions in the
following cases:
- Tuple literals with mutable elements (supporting deep nesting)
- Generator expressions
- Named expressions (walrus operator) containing mutable components
Preserves original formatting for assignment value:
```python
# Test case
def f5(x=([1, ])):
print(x)
```
```python
# Fix before
def f5(x=(None)):
if x is None:
x = [1]
print(x)
```
```python
# Fix after
def f5(x=None):
if x is None:
x = ([1, ])
print(x)
```
The expansion of detected expressions and the new fixes gated behind
previews.
## Test Plan
- Added B006_9.py with a bunch of test cases
- Generated snapshots
---------
Co-authored-by: Igor Drokin <drokinii1017@gmail.com>
Co-authored-by: dylwil3 <dylwil3@gmail.com>
ruff
673167a5 - [`flake8-bugbear`] Include certain guaranteed-mutable expressions: tuples, generators, and assignment expressions (`B006`) (#20024)
