[3.13] gh-119821: Support non-dict globals in LOAD_FROM_DICT_OR_GLOBALS (#119822)

Lib/test/test_type_aliases.py

@@ -1,4 +1,5 @@
 import pickle
+import textwrap
 import types
 import unittest
 from test.support import check_syntax_error, run_code
@@ -328,3 +329,22 @@ def test_pickling_local(self):
                 with self.subTest(thing=thing, proto=proto):
                     with self.assertRaises(pickle.PickleError):
                         pickle.dumps(thing, protocol=proto)
+
+
+class TypeParamsExoticGlobalsTest(unittest.TestCase):
+    def test_exec_with_unusual_globals(self):
+        class customdict(dict):
+            def __missing__(self, key):
+                return key
+
+        code = compile("type Alias = undefined", "test", "exec")
+        ns = customdict()
+        exec(code, ns)
+        Alias = ns["Alias"]
+        self.assertEqual(Alias.__value__, "undefined")
+
+        code = compile("class A: type Alias = undefined", "test", "exec")
+        ns = customdict()
+        exec(code, ns)
+        Alias = ns["A"].Alias
+        self.assertEqual(Alias.__value__, "undefined")

Misc/NEWS.d/next/Core and Builtins/2024-05-30-23-01-00.gh-issue-119821.jPGfvt.rst

@@ -0,0 +1,2 @@
+Fix execution of :ref:`annotation scopes <annotation-scopes>` within classes
+when ``globals`` is set to a non-dict. Patch by Jelle Zijlstra.

Python/bytecodes.c

@@ -1375,18 +1375,35 @@ dummy_func(
                 ERROR_NO_POP();
             }
             if (v == NULL) {
-                if (PyDict_GetItemRef(GLOBALS(), name, &v) < 0) {
-                    ERROR_NO_POP();
-                }
-                if (v == NULL) {
-                    if (PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0) {
+                if (PyDict_CheckExact(GLOBALS())
+                    && PyDict_CheckExact(BUILTINS()))
+                {
+                    v = _PyDict_LoadGlobal((PyDictObject *)GLOBALS(),
+                                            (PyDictObject *)BUILTINS(),
+                                            name);
+                    if (v == NULL) {
+                        if (!_PyErr_Occurred(tstate)) {
+                            /* _PyDict_LoadGlobal() returns NULL without raising
+                            * an exception if the key doesn't exist */
+                            _PyEval_FormatExcCheckArg(tstate, PyExc_NameError,
+                                                    NAME_ERROR_MSG, name);
+                        }
                         ERROR_NO_POP();
                     }
+                }
+                else {
+                    /* Slow-path if globals or builtins is not a dict */
+                    /* namespace 1: globals */
+                    ERROR_IF(PyMapping_GetOptionalItem(GLOBALS(), name, &v) < 0, error);
                     if (v == NULL) {
-                        _PyEval_FormatExcCheckArg(
-                                    tstate, PyExc_NameError,
-                                    NAME_ERROR_MSG, name);
-                        ERROR_NO_POP();
+                        /* namespace 2: builtins */
+                        ERROR_IF(PyMapping_GetOptionalItem(BUILTINS(), name, &v) < 0, error);
+                        if (v == NULL) {
+                            _PyEval_FormatExcCheckArg(
+                                        tstate, PyExc_NameError,
+                                        NAME_ERROR_MSG, name);
+                            ERROR_IF(true, error);
+                        }
                     }
                 }
             }