[flake8-simplify] add fix safety section (SIM110)

[VascoSch92]

The PR add the fix safety section for rule SIM110 (#15584 )

Unsafe Fix Example

def predicate(item):
    global called
    called += 1
    if called == 1:
    # after first call we change the method
        def new_predicate(_): return False
        globals()['predicate'] = new_predicate
    return True

def foo():
    for item in range(10):
        if predicate(item):
            return True
    return False

def foo_gen():
    return any(predicate(item) for item in range(10))

called = 0
print(foo())      # true – returns immediately on first call

called = 0
print(foo_gen())  # false – second call uses new `predicate`

Note

I notice that here we have two rules, SIM110 & SIM111. The second one seems not anymore active. Should I delete SIM111?

[github-actions]

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[ntBre]

That's quite an exotic example! I'm not sure if it's doing exactly what you think, though. I tried switching the order in which I call foo and foo_gen, and the output was still True and then False:

Original order

>>> def predicate(item):
...     global called
...     called += 1
...     if called == 1:
...     # after first call we change the method
...         def new_predicate(_): return False
...         globals()['predicate'] = new_predicate
...     return True
...
... def foo():
...     for item in range(10):
...         if predicate(item):
...             return True
...     return False
...
... def foo_gen():
...     return any(predicate(item) for item in range(10))
...
... called = 0
... print(foo())      # true – returns immediately on first call
...
... called = 0
... print(foo_gen())  # false – second call uses new `predicate`
...
True
False

Swapped order

>>> def predicate(item):
...     global called
...     called += 1
...     if called == 1:
...     # after first call we change the method
...         def new_predicate(_): return False
...         globals()['predicate'] = new_predicate
...     return True
...
... def foo():
...     for item in range(10):
...         if predicate(item):
...             return True
...     return False
...
... def foo_gen():
...     return any(predicate(item) for item in range(10))
...
... called = 0
... print(foo_gen())      # true – returns immediately on first call
...
... called = 0
... print(foo())  # false – second call uses new `predicate`
...
True
False

I think both versions use the same predicate for the whole loop, but called isn't actually getting reset between calls.

So removing comments might be the main reason for unsafety here.

[VascoSch92]

@ntBre You are right. :-)

I just added the fact it could remove comment.

Other question: we could make the fix safe when it doesn't remove comments right?

[ntBre]

Thanks!

Other question: we could make the fix safe when it doesn't remove comments right?

Yes, I think that's right since we couldn't come up with any other reason for the unsafety.