[3.13] gh-119821: Support non-dict globals in LOAD_FROM_DICT_OR_GLOBALS (#119822) (#119889)

dSupport non-dict globals in LOAD_FROM_DICT_OR_GLOBALS

The implementation basically copies LOAD_GLOBAL. Possibly it could be deduplicated,
but that seems like it may get hairy since the two operations have different operands.

This is important to fix in 3.14 for PEP 649, but it's a bug in earlier versions too,
and we should backport to 3.13 and 3.12 if possible.

(cherry picked from commit 80a4e3899420faaa012c82b4e82cdb6675a6a944)

1 files changed, 20 insertions, 0 deletions

diff --git a/Lib/test/test_type_aliases.py b/Lib/test/test_type_aliases.py
index 9c325bc..f8b395f 100644
--- a/Lib/test/test_type_aliases.py
+++ b/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 @@ class TypeAliasPickleTest(unittest.TestCase):
                 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")