2 files changed, 50 insertions, 58 deletions

diff --git a/Objects/abstract.c b/Objects/abstract.c
index 21c1ef1..c1d7789 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -1381,29 +1381,14 @@ Fail:
 	return -1;
 }
 
-/* Return -1 if error; 1 if v in w; 0 if v not in w. */
+/* Return -1 if error; 1 if ob in seq; 0 if ob not in seq.
+ * Always uses the iteration protocol, and only Py_EQ comparison.
+ */
 int
-PySequence_Contains(PyObject *w, PyObject *v) /* v in w */
+_PySequence_IterContains(PyObject *seq, PyObject *ob)
 {
-	PyObject *it;  /* iter(w) */
 	int result;
-
-	if (PyType_HasFeature(w->ob_type, Py_TPFLAGS_HAVE_SEQUENCE_IN)) {
-		PySequenceMethods *sq = w->ob_type->tp_as_sequence;
-	        if (sq != NULL && sq->sq_contains != NULL) {
-			result = (*sq->sq_contains)(w, v);
-			if (result >= 0)
-				return result;
-			assert(PyErr_Occurred());
-			if (PyErr_ExceptionMatches(PyExc_AttributeError))
-				PyErr_Clear();
-			else
-				return result;
-		}
-	}
-	
-	/* Try exhaustive iteration. */
-	it = PyObject_GetIter(w);
+	PyObject *it = PyObject_GetIter(seq);
 	if (it == NULL) {
 		PyErr_SetString(PyExc_TypeError,
 			"'in' or 'not in' needs iterable right argument");
@@ -1417,7 +1402,7 @@ PySequence_Contains(PyObject *w, PyObject *v) /* v in w */
 			result = PyErr_Occurred() ? -1 : 0;
 			break;
 		}
-		cmp = PyObject_RichCompareBool(v, item, Py_EQ);
+		cmp = PyObject_RichCompareBool(ob, item, Py_EQ);
 		Py_DECREF(item);
 		if (cmp == 0)
 			continue;
@@ -1428,6 +1413,20 @@ PySequence_Contains(PyObject *w, PyObject *v) /* v in w */
 	return result;
 }
 
+/* Return -1 if error; 1 if ob in seq; 0 if ob not in seq.
+ * Use sq_contains if possible, else defer to _PySequence_IterContains().
+ */
+int
+PySequence_Contains(PyObject *seq, PyObject *ob)
+{
+	if (PyType_HasFeature(seq->ob_type, Py_TPFLAGS_HAVE_SEQUENCE_IN)) {
+		PySequenceMethods *sqm = seq->ob_type->tp_as_sequence;
+	        if (sqm != NULL && sqm->sq_contains != NULL)
+			return (*sqm->sq_contains)(seq, ob);
+	}
+	return _PySequence_IterContains(seq, ob);
+}
+
 /* Backwards compatibility */
 #undef PySequence_In
 int
diff --git a/Objects/classobject.c b/Objects/classobject.c
index 2babbfb..67732ca 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -1131,11 +1131,15 @@ instance_ass_slice(PyInstanceObject *inst, int i, int j, PyObject *value)
 	return 0;
 }
 
-static int instance_contains(PyInstanceObject *inst, PyObject *member)
+static int
+instance_contains(PyInstanceObject *inst, PyObject *member)
 {
 	static PyObject *__contains__;
-	PyObject *func, *arg, *res;
-	int ret;
+	PyObject *func;
+
+	/* Try __contains__ first.
+	 * If that can't be done, try iterator-based searching.
+	 */
 
 	if(__contains__ == NULL) {
 		__contains__ = PyString_InternFromString("__contains__");
@@ -1143,45 +1147,34 @@ static int instance_contains(PyInstanceObject *inst, PyObject *member)
 			return -1;
 	}
 	func = instance_getattr(inst, __contains__);
-	if(func == NULL) {
-		/* fall back to previous behavior */
-		int i, cmp_res;
-
-		if(!PyErr_ExceptionMatches(PyExc_AttributeError))
+	if (func) {
+		PyObject *res;
+		int ret;
+		PyObject *arg = Py_BuildValue("(O)", member);
+		if(arg == NULL) {
+			Py_DECREF(func);
 			return -1;
-		PyErr_Clear();
-		for(i=0;;i++) {
-			PyObject *obj = instance_item(inst, i);
-			int ret = 0;
-
-			if(obj == NULL) {
-				if(!PyErr_ExceptionMatches(PyExc_IndexError))
-					return -1;
-				PyErr_Clear();
-				return 0;
-			}
-			if(PyObject_Cmp(obj, member, &cmp_res) == -1)
-				ret = -1;
-			if(cmp_res == 0) 
-				ret = 1;
-			Py_DECREF(obj);
-			if(ret)
-				return ret;
 		}
-	}
-	arg = Py_BuildValue("(O)", member);
-	if(arg == NULL) {
+		res = PyEval_CallObject(func, arg);
 		Py_DECREF(func);
-		return -1;
+		Py_DECREF(arg);
+		if(res == NULL) 
+			return -1;
+		ret = PyObject_IsTrue(res);
+		Py_DECREF(res);
+		return ret;
 	}
-	res = PyEval_CallObject(func, arg);
-	Py_DECREF(func);
-	Py_DECREF(arg);
-	if(res == NULL) 
+
+	/* Couldn't find __contains__. */
+	if (PyErr_ExceptionMatches(PyExc_AttributeError)) {
+		/* Assume the failure was simply due to that there is no
+		 * __contains__ attribute, and try iterating instead.
+		 */
+		PyErr_Clear();
+		return _PySequence_IterContains((PyObject *)inst, member);
+	}
+	else
 		return -1;
-	ret = PyObject_IsTrue(res);
-	Py_DECREF(res);
-	return ret;
 }
 
 static PySequenceMethods