Add a test for the new info, and fix 'name' for nested anonymous structs

Author: encukou

Lib/test/test_ctypes/test_structunion.py

@@ -4,7 +4,8 @@
 from ctypes import (Structure, Union, POINTER, sizeof, alignment,
                     c_char, c_byte, c_ubyte,
                     c_short, c_ushort, c_int, c_uint,
-                    c_long, c_ulong, c_longlong, c_ulonglong, c_float, c_double)
+                    c_long, c_ulong, c_longlong, c_ulonglong, c_float, c_double,
+                    c_int8, c_int16, c_int32)
 from ._support import (_CData, PyCStructType, UnionType,
                        Py_TPFLAGS_DISALLOW_INSTANTIATION,
                        Py_TPFLAGS_IMMUTABLETYPE)
@@ -175,6 +176,101 @@ class X(self.cls):
         # XXX Should we check nested data types also?
         # offset is always relative to the class...
 
+    def test_field_descriptor_attributes(self):
+        """Test information provided by the descriptors"""
+        class Inner(Structure):
+            _fields_ = [
+                ("a", c_int16),
+                ("b", c_int8, 1),
+                ("c", c_int8, 2),
+            ]
+        class X(self.cls):
+            _fields_ = [
+                ("x", c_int32),
+                ("y", c_int16, 1),
+                ("_", Inner),
+            ]
+            _anonymous_ = ["_"]
+
+        field_names = "xy_abc"
+
+        # name
+
+        for name in field_names:
+            with self.subTest(name=name):
+                self.assertEqual(getattr(X, name).name, name)
+
+        # type
+
+        expected_types = dict(
+            x=c_int32,
+            y=c_int16,
+            _=Inner,
+            a=c_int16,
+            b=c_int8,
+            c=c_int8,
+        )
+        assert set(expected_types) == set(field_names)
+        for name, tp in expected_types.items():
+            with self.subTest(name=name):
+                self.assertEqual(getattr(X, name).type, tp)
+                self.assertEqual(getattr(X, name).byte_size, sizeof(tp))
+
+        # offset, byte_offset
+
+        expected_offsets = dict(
+            x=(0, 0),
+            y=(0, 4),
+            _=(0, 6),
+            a=(0, 6),
+            b=(2, 8),
+            c=(2, 8),
+        )
+        assert set(expected_offsets) == set(field_names)
+        for name, (union_offset, struct_offset) in expected_offsets.items():
+            with self.subTest(name=name):
+                self.assertEqual(getattr(X, name).offset,
+                                 getattr(X, name).byte_offset)
+                if self.cls == Structure:
+                    self.assertEqual(getattr(X, name).offset, struct_offset)
+                else:
+                    self.assertEqual(getattr(X, name).offset, union_offset)
+
+        # is_bitfield, bit_size, bit_offset
+        # size
+
+        expected_bitfield_info = dict(
+            # (bit_size, bit_offset)
+            b=(1, 0),
+            c=(2, 1),
+            y=(1, 0),
+        )
+        for name in field_names:
+            with self.subTest(name=name):
+                if info := expected_bitfield_info.get(name):
+                    self.assertEqual(getattr(X, name).is_bitfield, True)
+                    expected_bit_size, expected_bit_offset = info
+                    self.assertEqual(getattr(X, name).bit_size,
+                                     expected_bit_size)
+                    self.assertEqual(getattr(X, name).bit_offset,
+                                     expected_bit_offset)
+                    self.assertEqual(getattr(X, name).size,
+                                     (expected_bit_size << 16)
+                                     | expected_bit_offset)
+                else:
+                    self.assertEqual(getattr(X, name).is_bitfield, False)
+                    type_size = sizeof(expected_types[name])
+                    self.assertEqual(getattr(X, name).bit_size, type_size * 8)
+                    self.assertEqual(getattr(X, name).bit_offset, 0)
+                    self.assertEqual(getattr(X, name).size, type_size)
+
+        # is_anonymous
+
+        for name in field_names:
+            with self.subTest(name=name):
+                self.assertEqual(getattr(X, name).is_anonymous, (name == '_'))
+
+
     def test_invalid_field_types(self):
         class POINT(self.cls):
             pass

Modules/_ctypes/stgdict.c

@@ -143,6 +143,7 @@ MakeFields(PyObject *type, CFieldObject *descr,
         new_descr->proto = Py_XNewRef(fdescr->proto);
         new_descr->getfunc = fdescr->getfunc;
         new_descr->setfunc = fdescr->setfunc;
+        new_descr->name = Py_NewRef(fdescr->name);
 
         Py_DECREF(fdescr);