bpo-29843: raise TypeError or ValueError when appropriate

Author: taleinat

Lib/ctypes/test/test_arrays.py

@@ -163,8 +163,6 @@ class Y(T):
         self.assertEqual(Y()._length_, 187)
 
     def test_bad_subclass(self):
-        import sys
-
         with self.assertRaises(AttributeError):
             class T(Array):
                 pass
@@ -174,29 +172,29 @@ class T(Array):
         with self.assertRaises(AttributeError):
             class T(Array):
                 _length_ = 13
-        with self.assertRaises(OverflowError):
-            class T(Array):
-                _type_ = c_int
-                _length_ = sys.maxsize * 2
-        with self.assertRaises(AttributeError):
-            class T(Array):
-                _type_ = c_int
-                _length_ = 1.87
 
     def test_bad_length(self):
-        with self.assertRaises(AttributeError):
+        import sys
+
+        with self.assertRaises(ValueError):
             class T(Array):
                 _type_ = c_int
-                _length_ = -1 << 1000
-        with self.assertRaises(AttributeError):
+                _length_ = - sys.maxsize * 2
+        with self.assertRaises(ValueError):
             class T(Array):
                 _type_ = c_int
                 _length_ = -1
+        with self.assertRaises(TypeError):
+            class T(Array):
+                _type_ = c_int
+                _length_ = 1.87
         with self.assertRaises(OverflowError):
             class T(Array):
                 _type_ = c_int
-                _length_ = 1 << 1000
-        # _length_ might be zero.
+                _length_ = sys.maxsize * 2
+
+    def test_zero_length(self):
+        # _length_ can be zero.
         class T(Array):
             _type_ = c_int
             _length_ = 0

Misc/NEWS.d/next/Core and Builtins/2018-10-21-17-43-48.bpo-29743.aeCcKR.rst

@@ -1,2 +1,4 @@
-Raise `AttributeError` instead of `OverflowError` in case of a negative
-``_length_`` in a `ctypes.Array` subclass.  Original patch by Oren Milman.
+Raise `ValueError` instead of `OverflowError` in case of a negative
+``_length_`` in a `ctypes.Array` subclass.  Also raise `TypeError`
+instead of `OverflowError` for non-integer ``_length_``.
+Original patch by Oren Milman.

Modules/_ctypes/_ctypes.c

@@ -1405,14 +1405,27 @@ PyCArrayType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     type_attr = NULL;
 
     length_attr = PyObject_GetAttrString((PyObject *)result, "_length_");
-    if (!length_attr ||
-        !PyLong_Check(length_attr) ||
-        _PyLong_Sign(length_attr) == -1)
-    {
-        PyErr_SetString(PyExc_AttributeError,
-                        "class must define a '_length_' attribute, "
-                        "which must be a positive integer");
-        Py_XDECREF(length_attr);
+    if (!length_attr) {
+        if (!PyErr_Occurred() ||
+            PyErr_ExceptionMatches(PyExc_AttributeError))
+        {
+            PyErr_SetString(PyExc_AttributeError,
+                            "class must define a '_length_' attribute");
+        }
+        goto error;
+    }
+
+    if (!PyLong_Check(length_attr)) {
+        Py_DECREF(length_attr);
+        PyErr_SetString(PyExc_TypeError,
+                        "The '_length_' attribute must be an integer");
+        goto error;
+    }
+
+    if (_PyLong_Sign(length_attr) == -1) {
+        Py_DECREF(length_attr);
+        PyErr_SetString(PyExc_ValueError,
+                        "The '_length_' attribute must not be negative");
         goto error;
     }