[3.13] gh-119311: Fix name mangling with PEP 695 generic classes (#119464) (#119643)

Fixes #119311. Fixes #119395.

(cherry picked from commit a9a74da4a0ca0645f049e67b6434a95e30592c32)

2 files changed, 96 insertions, 1 deletions

diff --git a/Lib/importlib/_bootstrap_external.py b/Lib/importlib/_bootstrap_external.py
index db44677..7742855 100644
--- a/Lib/importlib/_bootstrap_external.py
+++ b/Lib/importlib/_bootstrap_external.py
@@ -472,6 +472,7 @@ _code_type = type(_write_atomic.__code__)
 #     Python 3.13a1 3568 (Change semantics of END_FOR)
 #     Python 3.13a5 3569 (Specialize CONTAINS_OP)
 #     Python 3.13a6 3570 (Add __firstlineno__ class attribute)
+#     Python 3.13b1 3571 (Fix miscompilation of private names in generic classes)
 
 #     Python 3.14 will start with 3600
 
@@ -488,7 +489,7 @@ _code_type = type(_write_atomic.__code__)
 # Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
 # in PC/launcher.c must also be updated.
 
-MAGIC_NUMBER = (3570).to_bytes(2, 'little') + b'\r\n'
+MAGIC_NUMBER = (3571).to_bytes(2, 'little') + b'\r\n'
 
 _RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little')  # For import.c
 
diff --git a/Lib/test/test_type_params.py b/Lib/test/test_type_params.py
index 82f1007..aa9d408 100644
--- a/Lib/test/test_type_params.py
+++ b/Lib/test/test_type_params.py
@@ -823,6 +823,100 @@ class TypeParamsManglingTest(unittest.TestCase):
 
         self.assertEqual(Foo.Alias.__value__, (T, V))
 
+    def test_no_leaky_mangling_in_module(self):
+        ns = run_code("""
+            __before = "before"
+            class X[T]: pass
+            __after = "after"
+        """)
+        self.assertEqual(ns["__before"], "before")
+        self.assertEqual(ns["__after"], "after")
+
+    def test_no_leaky_mangling_in_function(self):
+        ns = run_code("""
+            def f():
+                class X[T]: pass
+                _X_foo = 2
+                __foo = 1
+                assert locals()['__foo'] == 1
+                return __foo
+        """)
+        self.assertEqual(ns["f"](), 1)
+
+    def test_no_leaky_mangling_in_class(self):
+        ns = run_code("""
+            class Outer:
+                __before = "before"
+                class Inner[T]:
+                    __x = "inner"
+                __after = "after"
+        """)
+        Outer = ns["Outer"]
+        self.assertEqual(Outer._Outer__before, "before")
+        self.assertEqual(Outer.Inner._Inner__x, "inner")
+        self.assertEqual(Outer._Outer__after, "after")
+
+    def test_no_mangling_in_bases(self):
+        ns = run_code("""
+            class __Base:
+                def __init_subclass__(self, **kwargs):
+                    self.kwargs = kwargs
+
+            class Derived[T](__Base, __kwarg=1):
+                pass
+        """)
+        Derived = ns["Derived"]
+        self.assertEqual(Derived.__bases__, (ns["__Base"], Generic))
+        self.assertEqual(Derived.kwargs, {"__kwarg": 1})
+
+    def test_no_mangling_in_nested_scopes(self):
+        ns = run_code("""
+            from test.test_type_params import make_base
+
+            class __X:
+                pass
+
+            class Y[T: __X](
+                make_base(lambda: __X),
+                # doubly nested scope
+                make_base(lambda: (lambda: __X)),
+                # list comprehension
+                make_base([__X for _ in (1,)]),
+                # genexp
+                make_base(__X for _ in (1,)),
+            ):
+                pass
+        """)
+        Y = ns["Y"]
+        T, = Y.__type_params__
+        self.assertIs(T.__bound__, ns["__X"])
+        base0 = Y.__bases__[0]
+        self.assertIs(base0.__arg__(), ns["__X"])
+        base1 = Y.__bases__[1]
+        self.assertIs(base1.__arg__()(), ns["__X"])
+        base2 = Y.__bases__[2]
+        self.assertEqual(base2.__arg__, [ns["__X"]])
+        base3 = Y.__bases__[3]
+        self.assertEqual(list(base3.__arg__), [ns["__X"]])
+
+    def test_type_params_are_mangled(self):
+        ns = run_code("""
+            from test.test_type_params import make_base
+
+            class Foo[__T, __U: __T](make_base(__T), make_base(lambda: __T)):
+                param = __T
+        """)
+        Foo = ns["Foo"]
+        T, U = Foo.__type_params__
+        self.assertEqual(T.__name__, "__T")
+        self.assertEqual(U.__name__, "__U")
+        self.assertIs(U.__bound__, T)
+        self.assertIs(Foo.param, T)
+
+        base1, base2, *_ = Foo.__bases__
+        self.assertIs(base1.__arg__, T)
+        self.assertIs(base2.__arg__(), T)
+
 
 class TypeParamsComplexCallsTest(unittest.TestCase):
     def test_defaults(self):