[flake8-bugbear] Mark the fix for unreliable-callable-check as always unsafe (B004) (#20318)

## Summary
Resolves #20282

Makes the rule fix always unsafe, because the replacement may not be
semantically equivalent to the original expression, potentially changing
the behavior of the code.

Updated docstring with examples.

## Test Plan
- Added two tests from issue and regenerated the snapshot

---------

Co-authored-by: Igor Drokin <drokinii1017@gmail.com>
Co-authored-by: Brent Westbrook <36778786+ntBre@users.noreply.github.com>

crates/ruff_linter/resources/test/fixtures/flake8_bugbear/B004.py

@@ -39,3 +39,16 @@ hasattr(
     "__call__",  # comment 4
     # comment 5
 )
+
+import operator
+
+assert hasattr(operator, "__call__")
+assert callable(operator) is False
+
+
+class A:
+    def __init__(self): self.__call__ = None
+
+
+assert hasattr(A(), "__call__")
+assert callable(A()) is False

crates/ruff_linter/src/rules/flake8_bugbear/rules/unreliable_callable_check.rs

@@ -28,10 +28,29 @@ use crate::{Edit, Fix, FixAvailability, Violation};
 /// ```
 ///
 /// ## Fix safety
-/// This rule's fix is marked as unsafe if there's comments in the `hasattr` call
+/// This rule's fix is marked as unsafe because the replacement may not be semantically
-/// expression, as comments may be removed.
+/// equivalent to the original expression, potentially changing the behavior of the code.
 ///
-/// For example, the fix would be marked as unsafe in the following case:
+/// For example, an imported module may have a `__call__` attribute but is not considered
+/// a callable object:
+/// ```python
+/// import operator
+///
+/// assert hasattr(operator, "__call__")
+/// assert callable(operator) is False
+/// ```
+/// Additionally, `__call__` may be defined only as an instance method:
+/// ```python
+/// class A:
+///     def __init__(self):
+///         self.__call__ = None
+///
+///
+/// assert hasattr(A(), "__call__")
+/// assert callable(A()) is False
+/// ```
+///
+/// Additionally, if there are comments in the `hasattr` call expression, they may be removed:
 /// ```python
 /// hasattr(
 ///     # comment 1
@@ -103,11 +122,7 @@ pub(crate) fn unreliable_callable_check(
             Ok(Fix::applicable_edits(
                 binding_edit,
                 import_edit,
-                if checker.comment_ranges().intersects(expr.range()) {
+                Applicability::Unsafe,
-                    Applicability::Unsafe
-                } else {
-                    Applicability::Safe
-                },
             ))
         });
     }

crates/ruff_linter/src/rules/flake8_bugbear/snapshots/ruff_linter__rules__flake8_bugbear__tests__B004_B004.py.snap

@@ -19,6 +19,7 @@ help: Replace with `callable()`
 4 |         print("Ooh, callable! Or is it?")
 5 |     if getattr(o, "__call__", False):
 6 |         print("Ooh, callable! Or is it?")
+note: This is an unsafe fix and may change runtime behavior
 
 B004 Using `hasattr(x, "__call__")` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
  --> B004.py:5:8
@@ -50,6 +51,7 @@ help: Replace with `callable()`
 13 |         print("B U G")
 14 |     if builtins.getattr(o, "__call__", False):
 15 |         print("B   U   G")
+note: This is an unsafe fix and may change runtime behavior
 
 B004 Using `hasattr(x, "__call__")` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
   --> B004.py:14:8
@@ -85,6 +87,7 @@ help: Replace with `callable()`
 26 |         print("STILL a bug!")
 27 | 
 28 | 
+note: This is an unsafe fix and may change runtime behavior
 
 B004 [*] Using `hasattr(x, "__call__")` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
   --> B004.py:35:1
@@ -99,6 +102,8 @@ B004 [*] Using `hasattr(x, "__call__")` to test if x is callable is unreliable.
 40 | |     # comment 5
 41 | | )
    | |_^
+42 |
+43 |   import operator
    |
 help: Replace with `callable()`
 32 | 
@@ -112,4 +117,43 @@ help: Replace with `callable()`
    -     # comment 5
    - )
 35 + callable(obj)
+36 | 
+37 | import operator
+38 | 
+note: This is an unsafe fix and may change runtime behavior
+
+B004 [*] Using `hasattr(x, "__call__")` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
+  --> B004.py:45:8
+   |
+43 | import operator
+44 |
+45 | assert hasattr(operator, "__call__")
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+46 | assert callable(operator) is False
+   |
+help: Replace with `callable()`
+42 | 
+43 | import operator
+44 | 
+   - assert hasattr(operator, "__call__")
+45 + assert callable(operator)
+46 | assert callable(operator) is False
+47 | 
+48 | 
+note: This is an unsafe fix and may change runtime behavior
+
+B004 [*] Using `hasattr(x, "__call__")` to test if x is callable is unreliable. Use `callable(x)` for consistent results.
+  --> B004.py:53:8
+   |
+53 | assert hasattr(A(), "__call__")
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^
+54 | assert callable(A()) is False
+   |
+help: Replace with `callable()`
+50 |     def __init__(self): self.__call__ = None
+51 | 
+52 | 
+   - assert hasattr(A(), "__call__")
+53 + assert callable(A())
+54 | assert callable(A()) is False
 note: This is an unsafe fix and may change runtime behavior