Fix FP `used-before-assignment` for statements guarded under same test (#8581)

1 files changed, 35 insertions, 0 deletions

diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index d82b5a8c8..8c9f6b6ae 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -811,6 +811,9 @@ scope_type : {self._atomic.scope_type}
                 continue
 
             outer_if = all_if[-1]
+            if NamesConsumer._node_guarded_by_same_test(node, outer_if):
+                continue
+
             # Name defined in the if/else control flow
             if NamesConsumer._inferred_to_define_name_raise_or_return(name, outer_if):
                 continue
@@ -820,6 +823,38 @@ scope_type : {self._atomic.scope_type}
         return uncertain_nodes
 
     @staticmethod
+    def _node_guarded_by_same_test(node: nodes.NodeNG, other_if: nodes.If) -> bool:
+        """Identify if `node` is guarded by an equivalent test as `other_if`.
+
+        Two tests are equivalent if their string representations are identical
+        or if their inferred values consist only of constants and those constants
+        are identical, and the if test guarding `node` is not a Name.
+        """
+        other_if_test_as_string = other_if.test.as_string()
+        other_if_test_all_inferred = utils.infer_all(other_if.test)
+        for ancestor in node.node_ancestors():
+            if not isinstance(ancestor, nodes.If):
+                continue
+            if ancestor.test.as_string() == other_if_test_as_string:
+                return True
+            if isinstance(ancestor.test, nodes.Name):
+                continue
+            all_inferred = utils.infer_all(ancestor.test)
+            if len(all_inferred) == len(other_if_test_all_inferred):
+                if any(
+                    not isinstance(test, nodes.Const)
+                    for test in (*all_inferred, *other_if_test_all_inferred)
+                ):
+                    continue
+                if {test.value for test in all_inferred} != {
+                    test.value for test in other_if_test_all_inferred
+                }:
+                    continue
+                return True
+
+        return False
+
+    @staticmethod
     def _uncertain_nodes_in_except_blocks(
         found_nodes: list[nodes.NodeNG],
         node: nodes.NodeNG,