Port test from PR-19850

matthiasgoergens · matthiasgoergens · commit ab42187f73dc · 2022-10-09T21:20:53.000+08:00
diff --git a/Lib/test/test_ctypes/test_bitfields.py b/Lib/test/test_ctypes/test_bitfields.py
@@ -303,6 +303,69 @@ class X(Structure):
             self.assertEqual(8, alignment(X))
             self.assertEqual(8, sizeof(X))
 
+    @unittest.skipIf(os.name == 'nt', reason='Posix only')
+    def test_packed_posix(self):
+        test_cases = {
+            (
+                ("a", c_uint8, 4),
+                ("b", c_uint8, 4),
+            ): 1,
+            (
+                ("a", c_uint8, 1),
+                ("b", c_uint16, 1),
+                ("c", c_uint32, 1),
+                ("d", c_uint64, 1),
+            ): 1,
+            (
+                ("a", c_uint8, 8),
+                ("b", c_uint16, 1),
+                ("c", c_uint32, 1),
+                ("d", c_uint64, 1),
+            ): 2,
+            (
+                ("a", c_uint32, 9),
+                ("b", c_uint16, 10),
+                ("c", c_uint32, 25),
+                ("d", c_uint64, 1),
+            ): 6,
+            (
+                ("a", c_uint32, 9),
+                ("b", c_uint16, 10),
+                ("c", c_uint32, 25),
+                ("d", c_uint64, 5),
+            ): 7,
+            (
+                ("a", c_uint16),
+                ("b", c_uint16, 9),
+                ("c", c_uint16, 1),
+                ("d", c_uint16, 1),
+                ("e", c_uint16, 1),
+                ("f", c_uint16, 1),
+                ("g", c_uint16, 3),
+                ("h", c_uint32, 10),
+                ("i", c_uint32, 20),
+                ("j", c_uint32, 2),
+            ): 8,
+            (
+                ("a", c_uint16, 9),
+                ("b", c_uint16, 10),
+                ("d", c_uint16),
+                ("c", c_uint8, 8),
+            ): 6,
+            (
+                ("a", c_uint32, 9),
+                ("b", c_uint32),
+                ("c", c_uint32, 8),
+            ): 7,
+        }
+
+        for fields, size in test_cases.items():
+            with self.subTest(fields=fields):
+                class X(Structure):
+                    _pack_ = 1
+                    _fields_ = list(fields)
+                self.assertEqual(sizeof(X), size)
+
     def test_gh_95496(self):
         for field_width in range(1, 33):
             class TestStruct(Structure):
