Fix a false positive for simplify-boolean-expression when multiple values inferred

doc/whatsnew/fragments/7626.false_positive

@@ -0,0 +1,6 @@
+Fix a false positive for ``simplify-boolean-expression`` when multiple values
+are inferred for a constant.
+
+Adds a keyword-only ``compare_constants`` argument to ``safe_infer``.
+
+Closes #7626

pylint/checkers/refactoring/refactoring_checker.py

@@ -21,7 +21,7 @@
 from pylint import checkers
 from pylint.checkers import utils
 from pylint.checkers.utils import node_frame_class
-from pylint.interfaces import HIGH
+from pylint.interfaces import HIGH, INFERENCE
 
 if TYPE_CHECKING:
     from pylint.lint import PyLinter
@@ -1495,19 +1495,18 @@ def visit_return(self, node: nodes.Return | nodes.Assign) -> None:
         ):
             return
 
-        inferred_truth_value = utils.safe_infer(truth_value)
+        inferred_truth_value = utils.safe_infer(truth_value, compare_constants=True)
         if inferred_truth_value is None or inferred_truth_value == astroid.Uninferable:
-            truth_boolean_value = True
-        else:
-            truth_boolean_value = inferred_truth_value.bool_value()
+            return
+        truth_boolean_value = inferred_truth_value.bool_value()
 
         if truth_boolean_value is False:
             message = "simplify-boolean-expression"
             suggestion = false_value.as_string()
         else:
             message = "consider-using-ternary"
             suggestion = f"{truth_value.as_string()} if {cond.as_string()} else {false_value.as_string()}"
-        self.add_message(message, node=node, args=(suggestion,))
+        self.add_message(message, node=node, args=(suggestion,), confidence=INFERENCE)
 
     def _append_context_managers_to_stack(self, node: nodes.Assign) -> None:
         if _is_inside_context_manager(node):

pylint/checkers/utils.py

@@ -1343,12 +1343,18 @@ def _get_python_type_of_node(node: nodes.NodeNG) -> str | None:
 
 @lru_cache(maxsize=1024)
 def safe_infer(
-    node: nodes.NodeNG, context: InferenceContext | None = None
+    node: nodes.NodeNG,
+    context: InferenceContext | None = None,
+    *,
+    compare_constants: bool = False,
 ) -> InferenceResult | None:
     """Return the inferred value for the given node.
 
     Return None if inference failed or if there is some ambiguity (more than
     one node has been inferred of different types).
+
+    If compare_constants is True and if multiple constants are inferred,
+    unequal inferred values are also considered ambiguous and return None.
     """
     inferred_types: set[str | None] = set()
     try:
@@ -1362,11 +1368,21 @@ def safe_infer(
     if value is not astroid.Uninferable:
         inferred_types.add(_get_python_type_of_node(value))
 
+    first_constant_value = None
+    if compare_constants and isinstance(value, nodes.Const):
+        first_constant_value = value.value
+
     try:
         for inferred in infer_gen:
             inferred_type = _get_python_type_of_node(inferred)
             if inferred_type not in inferred_types:
                 return None  # If there is ambiguity on the inferred node.
+            if (
+                compare_constants
+                and isinstance(inferred, nodes.Const)
+                and inferred.value != first_constant_value
+            ):
+                return None
             if (
                 isinstance(inferred, nodes.FunctionDef)
                 and inferred.args.args is not None

tests/functional/t/ternary.py

@@ -1,18 +1,21 @@
 """Test for old ternary constructs"""
-from UNINFERABLE import condition, true_value, false_value, some_callable  # pylint: disable=import-error
+from UNINFERABLE import condition, some_callable  # pylint: disable=import-error
 
-SOME_VALUE1 = true_value if condition else false_value
-SOME_VALUE2 = condition and true_value or false_value  # [consider-using-ternary]
+TRUE_VALUE = True
+FALSE_VALUE = False
+
+SOME_VALUE1 = TRUE_VALUE if condition else FALSE_VALUE
+SOME_VALUE2 = condition and TRUE_VALUE or FALSE_VALUE  # [consider-using-ternary]
 SOME_VALUE3 = condition
 
 def func1():
     """Ternary return value correct"""
-    return true_value if condition else false_value
+    return TRUE_VALUE if condition else FALSE_VALUE
 
 
 def func2():
     """Ternary return value incorrect"""
-    return condition and true_value or false_value  # [consider-using-ternary]
+    return condition and TRUE_VALUE or FALSE_VALUE  # [consider-using-ternary]
 
 
 SOME_VALUE4 = some_callable(condition) and 'ERROR' or 'SUCCESS'  # [consider-using-ternary]
@@ -30,10 +33,23 @@ def func2():
 def func4():
     """"Using a Name as a condition but still emits"""
     truth_value = 42
-    return condition and truth_value or false_value # [consider-using-ternary]
+    return condition and truth_value or FALSE_VALUE # [consider-using-ternary]
 
 
 def func5():
     """"Using a Name that infers to False as a condition does not emit"""
     falsy_value = False
-    return condition and falsy_value or false_value # [simplify-boolean-expression]
+    return condition and falsy_value or FALSE_VALUE # [simplify-boolean-expression]
+
+
+def func_control_flow():
+    """Redefining variables should invalidate simplify-boolean-expression."""
+    flag_a = False
+    flag_b = False
+    for num in range(2):
+        if num == 1:
+            flag_a = True
+        else:
+            flag_b = True
+    multiple = (flag_a and flag_b) or func5()
+    return multiple

tests/functional/t/ternary.txt

@@ -1,8 +1,8 @@
-consider-using-ternary:5:0:5:53::Consider using ternary (true_value if condition else false_value):UNDEFINED
-consider-using-ternary:15:4:15:50:func2:Consider using ternary (true_value if condition else false_value):UNDEFINED
-consider-using-ternary:18:0:18:63::Consider using ternary ('ERROR' if some_callable(condition) else 'SUCCESS'):UNDEFINED
-consider-using-ternary:19:0:19:60::Consider using ternary ('greater' if SOME_VALUE1 > 3 else 'not greater'):UNDEFINED
-consider-using-ternary:20:0:20:67::Consider using ternary ('both' if SOME_VALUE2 > 4 and SOME_VALUE3 else 'not'):UNDEFINED
-simplify-boolean-expression:23:0:23:50::Boolean expression may be simplified to SOME_VALUE2:UNDEFINED
-consider-using-ternary:33:4:33:51:func4:Consider using ternary (truth_value if condition else false_value):UNDEFINED
-simplify-boolean-expression:39:4:39:51:func5:Boolean expression may be simplified to false_value:UNDEFINED
+consider-using-ternary:8:0:8:53::Consider using ternary (TRUE_VALUE if condition else FALSE_VALUE):INFERENCE
+consider-using-ternary:18:4:18:50:func2:Consider using ternary (TRUE_VALUE if condition else FALSE_VALUE):INFERENCE
+consider-using-ternary:21:0:21:63::Consider using ternary ('ERROR' if some_callable(condition) else 'SUCCESS'):INFERENCE
+consider-using-ternary:22:0:22:60::Consider using ternary ('greater' if SOME_VALUE1 > 3 else 'not greater'):INFERENCE
+consider-using-ternary:23:0:23:67::Consider using ternary ('both' if SOME_VALUE2 > 4 and SOME_VALUE3 else 'not'):INFERENCE
+simplify-boolean-expression:26:0:26:50::Boolean expression may be simplified to SOME_VALUE2:INFERENCE
+consider-using-ternary:36:4:36:51:func4:Consider using ternary (truth_value if condition else FALSE_VALUE):INFERENCE
+simplify-boolean-expression:42:4:42:51:func5:Boolean expression may be simplified to FALSE_VALUE:INFERENCE