gh-125723: Fix crash with f_locals when generator frame outlive their generator (#126956)

Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
Co-authored-by: Alyssa Coghlan <ncoghlan@gmail.com>

Lib/test/test_generators.py

@@ -652,6 +652,89 @@ class GeneratorCloseTest(unittest.TestCase):
         self.assertIsNone(f_wr())
 
 
+# See https://github.com/python/cpython/issues/125723
+class GeneratorDeallocTest(unittest.TestCase):
+    def test_frame_outlives_generator(self):
+        def g1():
+            a = 42
+            yield sys._getframe()
+
+        def g2():
+            a = 42
+            yield
+
+        def g3(obj):
+            a = 42
+            obj.frame = sys._getframe()
+            yield
+
+        class ObjectWithFrame():
+            def __init__(self):
+                self.frame = None
+
+        def get_frame(index):
+            if index == 1:
+                return next(g1())
+            elif index == 2:
+                gen = g2()
+                next(gen)
+                return gen.gi_frame
+            elif index == 3:
+                obj = ObjectWithFrame()
+                next(g3(obj))
+                return obj.frame
+            else:
+                return None
+
+        for index in (1, 2, 3):
+            with self.subTest(index=index):
+                frame = get_frame(index)
+                frame_locals = frame.f_locals
+                self.assertIn('a', frame_locals)
+                self.assertEqual(frame_locals['a'], 42)
+
+    def test_frame_locals_outlive_generator(self):
+        frame_locals1 = None
+
+        def g1():
+            nonlocal frame_locals1
+            frame_locals1 = sys._getframe().f_locals
+            a = 42
+            yield
+
+        def g2():
+            a = 42
+            yield sys._getframe().f_locals
+
+        def get_frame_locals(index):
+            if index == 1:
+                nonlocal frame_locals1
+                next(g1())
+                return frame_locals1
+            if index == 2:
+                return next(g2())
+            else:
+                return None
+
+        for index in (1, 2):
+            with self.subTest(index=index):
+                frame_locals = get_frame_locals(index)
+                self.assertIn('a', frame_locals)
+                self.assertEqual(frame_locals['a'], 42)
+
+    def test_frame_locals_outlive_generator_with_exec(self):
+        def g():
+            a = 42
+            yield locals(), sys._getframe().f_locals
+
+        locals_ = {'g': g}
+        for i in range(10):
+            exec("snapshot, live_locals = next(g())", locals=locals_)
+            for l in (locals_['snapshot'], locals_['live_locals']):
+                self.assertIn('a', l)
+                self.assertEqual(l['a'], 42)
+
+
 class GeneratorThrowTest(unittest.TestCase):
 
     def test_exception_context_with_yield(self):