More focused version of the changeset

Signed-off-by: Matthew A Johnson <matjoh@microsoft.com>

Author: matajoh

Include/internal/pycore_immutability.h

@@ -12,10 +12,6 @@ extern "C" {
 PyObject* _Py_Freeze(PyObject*);
 #define Py_Freeze(op) _Py_Freeze(_PyObject_CAST(op))
 
-PyObject* _Py_FreezeGlobals(void);
-
-bool _Py_GlobalsImmutable_Check(void);
-
 #ifdef __cplusplus
 }
 #endif

Include/internal/pycore_object.h

@@ -100,16 +100,7 @@ static inline void _Py_SetImmutable(PyObject *op)
 }
 #define _Py_SetImmutable(op) _Py_SetImmutable(_PyObject_CAST(op))
 
-/* _Py_ClearImmutable() should only be used during object deallocation and runtime finalization. */
-static inline void _Py_ClearImmutable(PyObject *op)
-{
-    if (op) {
-        op->ob_refcnt &= _Py_REFCNT_MASK;
-    }
-}
-#define _Py_ClearImmutable(op) _Py_ClearImmutable(_PyObject_CAST(op))
-
-#define Py_CHECKWRITE(op) ((op) && (!_Py_IsImmutable(op)))
+#define Py_CHECKWRITE(op) ((op) && (!_Py_IsImmutable(op) || _Py_IsFinalizing()))
 #define Py_REQUIREWRITE(op, msg) {if (Py_CHECKWRITE(op)) { _PyObject_ASSERT_FAILED_MSG(op, msg); }}
 
 static inline void

Lib/test/test_freeze.py

@@ -400,16 +400,14 @@ def test_weakref(self):
         # self.assertTrue(c.val() is obj)
         self.assertIsNone(c.val())
 
-# This test will make the Python environment unusable.
-# Should perhaps forbid making the frame immutable.
-# class TestStackCapture(unittest.TestCase):
-#     def test_stack_capture(self):
-#         import sys
-#         x = {}
-#         x["frame"] = sys._getframe()
-#         freeze(x)
-#         self.assertTrue(isimmutable(x))
-#         self.assertTrue(isimmutable(x["frame"]))
+class TestStackCapture(unittest.TestCase):
+     def test_stack_capture(self):
+         import sys
+         x = {}
+         x["frame"] = sys._getframe()
+         freeze(x)
+         self.assertTrue(isimmutable(x))
+         self.assertTrue(isimmutable(x["frame"]))
 
 global_test_dict = 0
 class TestGlobalDictMutation(unittest.TestCase):
@@ -426,5 +424,39 @@ def test_global_dict_mutation(self):
         self.assertRaises(NotWriteableError, f1)
 
 
+class TestSubclass(unittest.TestCase):
+    def test_subclass(self):
+        class C:
+            def __init__(self, val):
+                self.val = val
+
+            def a(self):
+                return self.val
+
+            def b(self, val):
+                self.val = val
+
+        c_obj = C(1)
+        freeze(c_obj)
+        self.assertTrue(isimmutable(c_obj))
+        self.assertTrue(isimmutable(C))
+        class D(C):
+            def __init__(self, val):
+                super().__init__(val)
+                self.val2 = val * 2
+
+            def b(self):
+                return self.val2
+
+            def c(self, val):
+                self.val = val
+
+        d_obj = D(1)
+        self.assertEqual(d_obj.a(), 1)
+        self.assertEqual(d_obj.b(), 2)
+        self.assertTrue(isinstance(d_obj, C))
+        self.assertTrue(issubclass(D, C))
+
+
 if __name__ == '__main__':
     unittest.main()

Lib/test/test_freezeglobals.py

@@ -1026,7 +1026,6 @@ delete_garbage(PyThreadState *tstate, GCState *gcstate,
             inquiry clear;
             if ((clear = Py_TYPE(op)->tp_clear) != NULL) {
                 Py_INCREF(op);
-                _Py_ClearImmutable(op);
                 (void) clear(op);
                 if (_PyErr_Occurred(tstate)) {
                     _PyErr_WriteUnraisableMsg("in tp_clear of",

Modules/gcmodule.c

@@ -40,7 +40,7 @@ immutable_error(void)
     PyThreadState *tstate = _PyThreadState_GET();
     if (!_PyErr_Occurred(tstate)) {
         _PyErr_SetString(tstate, PyExc_NotWriteableError,
-                         "can't modify immutable instance");
+                         "cannot modify immutable instance");
     }
     return NULL;
 }

Objects/abstract.c

@@ -602,7 +602,6 @@ _PyModule_Clear(PyObject *m)
 {
     PyObject *d = ((PyModuleObject *)m)->md_dict;
     if (d != NULL){
-        _Py_ClearImmutable(d);
         _PyModule_ClearDict(d);
     }
 }
@@ -622,8 +621,6 @@ _PyModule_ClearDict(PyObject *d)
 
     int verbose = _Py_GetConfig()->verbose;
 
-    // VPYTODO add code to omit immutable keys from this (similar to __builtins__)
-
     /* First, clear only names starting with a single underscore */
     pos = 0;
     while (PyDict_Next(d, &pos, &key, &value)) {

Objects/moduleobject.c

@@ -2625,7 +2625,6 @@ _PyObject_AssertFailed(PyObject *obj, const char *expr, const char *msg,
 void
 _Py_Dealloc(PyObject *op)
 {
-    _Py_ClearImmutable(op);
     PyTypeObject *type = Py_TYPE(op);
     destructor dealloc = type->tp_dealloc;
 #ifdef Py_DEBUG

Objects/object.c

@@ -5304,7 +5304,6 @@ type_clear(PyTypeObject *type)
     PyType_Modified(type);
     PyObject *dict = lookup_tp_dict(type);
     if (dict) {
-        _Py_ClearImmutable(dict);
         PyDict_Clear(dict);
     }
     Py_CLEAR(((PyHeapTypeObject *)type)->ht_module);

Objects/typeobject.c

@@ -2772,19 +2772,6 @@ builtin_freeze(PyObject *module, PyObject *obj)
     return Py_Freeze(obj);
 }
 
-/*[clinic input]
-freezeglobals as builtin_freezeglobals
-
-Make all globals and the global dictionary immutable.
-[clinic start generated code]*/
-
-static PyObject *
-builtin_freezeglobals_impl(PyObject *module)
-/*[clinic end generated code: output=4cd596c15daee779 input=b91735d8218dcb6b]*/
-{
-    return _Py_FreezeGlobals();
-}
-
 
 typedef struct {
     PyObject_HEAD
@@ -3086,7 +3073,6 @@ static PyMethodDef builtin_methods[] = {
     BUILTIN_ISSUBCLASS_METHODDEF
     BUILTIN_ISIMMUTABLE_METHODDEF
     BUILTIN_FREEZE_METHODDEF
-    BUILTIN_FREEZEGLOBALS_METHODDEF
     BUILTIN_ITER_METHODDEF
     BUILTIN_AITER_METHODDEF
     BUILTIN_LEN_METHODDEF