gh-104377: fix cell in comprehension that is free in outer scope (#104394)

1 files changed, 55 insertions, 4 deletions

diff --git a/Lib/test/test_listcomps.py b/Lib/test/test_listcomps.py
index 1cc202b..b2a3b7e 100644
--- a/Lib/test/test_listcomps.py
+++ b/Lib/test/test_listcomps.py
@@ -117,15 +117,15 @@ class ListComprehensionTest(unittest.TestCase):
                     newcode = code
                     def get_output(moddict, name):
                         return moddict[name]
-                ns = ns or {}
+                newns = ns.copy() if ns else {}
                 try:
-                    exec(newcode, ns)
+                    exec(newcode, newns)
                 except raises as e:
                     # We care about e.g. NameError vs UnboundLocalError
                     self.assertIs(type(e), raises)
                 else:
                     for k, v in (outputs or {}).items():
-                        self.assertEqual(get_output(ns, k), v)
+                        self.assertEqual(get_output(newns, k), v)
 
     def test_lambdas_with_iteration_var_as_default(self):
         code = """
@@ -180,6 +180,26 @@ class ListComprehensionTest(unittest.TestCase):
             z = [x() for x in items]
         """
         outputs = {"z": [2, 2, 2, 2, 2]}
+        self._check_in_scopes(code, outputs, scopes=["module", "function"])
+
+    def test_cell_inner_free_outer(self):
+        code = """
+            def f():
+                return [lambda: x for x in (x, [1])[1]]
+            x = ...
+            y = [fn() for fn in f()]
+        """
+        outputs = {"y": [1]}
+        self._check_in_scopes(code, outputs, scopes=["module", "function"])
+
+    def test_free_inner_cell_outer(self):
+        code = """
+            g = 2
+            def f():
+                return g
+            y = [g for x in [1]]
+        """
+        outputs = {"y": [2]}
         self._check_in_scopes(code, outputs)
 
     def test_inner_cell_shadows_outer_redefined(self):
@@ -203,6 +223,37 @@ class ListComprehensionTest(unittest.TestCase):
         outputs = {"x": -1}
         self._check_in_scopes(code, outputs, ns={"g": -1})
 
+    def test_explicit_global(self):
+        code = """
+            global g
+            x = g
+            g = 2
+            items = [g for g in [1]]
+            y = g
+        """
+        outputs = {"x": 1, "y": 2, "items": [1]}
+        self._check_in_scopes(code, outputs, ns={"g": 1})
+
+    def test_explicit_global_2(self):
+        code = """
+            global g
+            x = g
+            g = 2
+            items = [g for x in [1]]
+            y = g
+        """
+        outputs = {"x": 1, "y": 2, "items": [2]}
+        self._check_in_scopes(code, outputs, ns={"g": 1})
+
+    def test_explicit_global_3(self):
+        code = """
+            global g
+            fns = [lambda: g for g in [2]]
+            items = [fn() for fn in fns]
+        """
+        outputs = {"items": [2]}
+        self._check_in_scopes(code, outputs, ns={"g": 1})
+
     def test_assignment_expression(self):
         code = """
             x = -1
@@ -250,7 +301,7 @@ class ListComprehensionTest(unittest.TestCase):
             g()
         """
         outputs = {"x": 1}
-        self._check_in_scopes(code, outputs)
+        self._check_in_scopes(code, outputs, scopes=["module", "function"])
 
     def test_introspecting_frame_locals(self):
         code = """