[used-before-assignment] Fix FP for try/else/continue (#9374)

Author: jacobtylerwalls

doc/whatsnew/fragments/6804.false_positive

@@ -0,0 +1,5 @@
+``used-before-assignment`` is no longer emitted when using a name in a loop and
+depending on an earlier name assignment in an ``except`` block paired with
+``else: continue``.
+
+Closes #6804

pylint/checkers/variables.py

@@ -883,6 +883,16 @@ def _uncertain_nodes_in_except_blocks(
                 and utils.is_terminating_func(else_statement.value)
                 for else_statement in closest_try_except.orelse
             )
+            else_block_continues = any(
+                isinstance(else_statement, nodes.Continue)
+                for else_statement in closest_try_except.orelse
+            )
+            if (
+                else_block_continues
+                and isinstance(node_statement.parent, (nodes.For, nodes.While))
+                and closest_try_except.parent.parent_of(node_statement)
+            ):
+                continue
 
             if try_block_returns or else_block_returns or else_block_exits:
                 # Exception: if this node is in the final block of the other_node_statement,

tests/functional/u/used/used_before_assignment_else_continue.py

@@ -0,0 +1,42 @@
+"""If the else block continues, it is generally safe to rely on assignments in the except,
+inside the same for loop only."""
+
+
+def safe():
+    """Name used safely inside the loop."""
+    while True:
+        try:
+            pass
+        except ValueError:
+            error = True
+        else:
+            continue
+
+        print(error)
+
+
+def halfway_safe():
+    """Name used safely inside the loop, unsafely outside it."""
+    for _temp in range(0, 1):
+        try:
+            pass
+        except ValueError:
+            error = True
+        else:
+            continue
+
+        print(error)
+    print(error)  # https://github.com/pylint-dev/pylint/issues/9379
+
+
+def unsafe():
+    """Name used unsafely outside the loop."""
+    for _temp in range(0, 1):
+        try:
+            pass
+        except ValueError:
+            error = True
+        else:
+            continue
+
+    print(error)  # [used-before-assignment]

tests/functional/u/used/used_before_assignment_else_continue.txt

@@ -0,0 +1 @@
+used-before-assignment:42:10:42:15:unsafe:Using variable 'error' before assignment:CONTROL_FLOW