Merge pull request #34 from nanjekyejoannah/warn_string_cmp_with_recent_assumptions

Warn for string cmp with new string warning assumptions

Author: ltratt

Lib/test/test_StringIO.py

@@ -166,6 +166,23 @@ def test_unicode(self):
         self.assertEqual(s, unicode('abcuvwxyz!'))
         self.assertEqual(type(s), types.UnicodeType)
 
+    def test_py3k_string_cmp(self):
+        "abc" == 123
+        "abc" == object()
+        u"abc" == 123
+        u"abc" == object()
+        with test_support.check_py3k_warnings(("comparing unicode and byte strings has different semantics in 3.x: convert the first string to bytes.",
+                                             DeprecationWarning)):
+            u"test str" == "test unicode"
+        deprecations = []
+        if sys.py3kwarning:
+            deprecations += [
+                ("comparing unicode and byte strings has different semantics in 3.x: convert the second string to byte.", DeprecationWarning),
+                ("comparing unicode and byte strings has different semantics in 3.x: convert the first string to bytes.", DeprecationWarning)
+            ]
+        with test_support.check_py3k_warnings(*deprecations):
+            "test str" == u"test unicode"
+
 class TestcStringIO(TestGenericStringIO):
     MODULE = cStringIO
 

Objects/stringobject.c

@@ -1209,6 +1209,9 @@ string_richcompare(PyStringObject *a, PyStringObject *b, int op)
     PyObject *result;
 
     /* Make sure both arguments are strings. */
+    if ((PyString_Check(a) && PyUnicode_Check(b)) && PyErr_WarnPy3k("comparing unicode and byte strings has different semantics in 3.x: convert the second string to byte.", 1) < 0) {
+        goto out;
+    }
     if (!(PyString_Check(a) && PyString_Check(b))) {
         result = Py_NotImplemented;
         goto out;

Objects/unicodeobject.c

@@ -6269,6 +6269,10 @@ PyObject *PyUnicode_RichCompare(PyObject *left,
 {
     int result;
 
+    if (PyString_Check(right) && PyErr_WarnPy3k("comparing unicode and byte strings has different semantics in 3.x: convert the first string to bytes.", 1) < 0){
+        goto onError;
+    }
+
     result = PyUnicode_Compare(left, right);
     if (result == -1 && PyErr_Occurred())
         goto onError;