gh-136203: Improve TypeError msg when comparing two MappingProxyTypes (#136204)

sobolevn · vstinner · web-flow · commit 41a9b46ad478 · 2025-07-02T19:05:28.000+03:00
Co-authored-by: Victor Stinner &lt;vstinner@python.org&gt;
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
@@ -1376,6 +1376,27 @@ def __hash__(self):
         view = self.mappingproxy(mapping)
         self.assertEqual(hash(view), hash(mapping))
 
+    def test_richcompare(self):
+        mp1 = self.mappingproxy({'a': 1})
+        mp1_2 = self.mappingproxy({'a': 1})
+        mp2 = self.mappingproxy({'a': 2})
+
+        self.assertTrue(mp1 == mp1_2)
+        self.assertFalse(mp1 != mp1_2)
+        self.assertFalse(mp1 == mp2)
+        self.assertTrue(mp1 != mp2)
+
+        msg = "not supported between instances of 'mappingproxy' and 'mappingproxy'"
+
+        with self.assertRaisesRegex(TypeError, msg):
+            mp1 > mp2
+        with self.assertRaisesRegex(TypeError, msg):
+            mp1 < mp1_2
+        with self.assertRaisesRegex(TypeError, msg):
+            mp2 >= mp2
+        with self.assertRaisesRegex(TypeError, msg):
+            mp1_2 <= mp1
+
 
 class ClassCreationTests(unittest.TestCase):
 
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-07-02-15-18-41.gh-issue-136203.Y934sC.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-07-02-15-18-41.gh-issue-136203.Y934sC.rst
@@ -0,0 +1,2 @@
+Improve :exc:`TypeError` error message, when richcomparing two
+:class:`types.MappingProxyType` objects.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
@@ -1233,7 +1233,10 @@ static PyObject *
 mappingproxy_richcompare(PyObject *self, PyObject *w, int op)
 {
     mappingproxyobject *v = (mappingproxyobject *)self;
-    return PyObject_RichCompare(v->mapping, w, op);
+    if (op == Py_EQ || op == Py_NE) {
+        return PyObject_RichCompare(v->mapping, w, op);
+    }
+    Py_RETURN_NOTIMPLEMENTED;
 }
 
 static int

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+Improve :exc:`TypeError` error message, when richcomparing two
	`2`	+:class:`types.MappingProxyType` objects.
Original file line number	Diff line number	Diff line change
`@@ -1233,7 +1233,10 @@ static PyObject *`
`1233`	`1233`	`mappingproxy_richcompare(PyObject self, PyObject w, int op)`
`1234`	`1234`	`{`
`1235`	`1235`	`mappingproxyobject v = (mappingproxyobject )self;`
`1236`		`- return PyObject_RichCompare(v->mapping, w, op);`
	`1236`	`+ if (op == Py_EQ \|\| op == Py_NE) {`
	`1237`	`+ return PyObject_RichCompare(v->mapping, w, op);`
	`1238`	`+ }`
	`1239`	`+ Py_RETURN_NOTIMPLEMENTED;`
`1237`	`1240`	`}`
`1238`	`1241`
`1239`	`1242`	`static int`