gh-65329: Equivalent functools.partial instances should compare equal

Lib/test/test_functools.py

@@ -222,6 +222,26 @@ def test_repr(self):
                       [f'{name}({capture!r}, {args_repr}, {kwargs_repr})'
                        for kwargs_repr in kwargs_reprs])
 
+    def test_equality(self):
+        p = functools.partial(capture, 1, 2, a=10, b=20)
+        q = functools.partial(capture, 1, 2, a=10, b=20)
+        self.assertTrue(p == q)
+        self.assertFalse(p != q)
+        self.assertTrue(p.__eq__(q))
+        self.assertFalse(p.__ne__(q))
+
+        q = self.partial(capture, 1, 2, a=10)
+        self.assertFalse(p == q)
+        self.assertTrue(p != q)
+
+        self.assertNotEqual(p, capture)
+        self.assertNotEqual(q, capture)
+
+        a = self.partial(capture)
+        b = self.partial(signature)
+        self.assertFalse(a == b)
+        self.assertTrue(a != b)
+
     def test_recursive_repr(self):
         if self.partial in (c_functools.partial, py_functools.partial):
             name = 'functools.partial'

Modules/_functoolsmodule.c

@@ -477,6 +477,43 @@ static PyMethodDef partial_methods[] = {
     {NULL,              NULL}           /* sentinel */
 };
 
+static PyObject *
+partial_richcompare(PyObject *self, PyObject *other, int op)
+{
+    partialobject *a, *b;
+    PyObject *res;
+    int eq;
+
+    if (op != Py_EQ && op != Py_NE) {
+        Py_RETURN_NOTIMPLEMENTED;
+    }
+
+    a = (partialobject *) self;
+    b = (partialobject *) other;
+
+    eq = PyObject_RichCompareBool(a->fn, b->fn, Py_EQ);
+    if (eq == 1) {
+        eq = PyObject_RichCompareBool(a->args, b->args, Py_EQ);
+        if (eq == 1) {
+            eq = PyObject_RichCompareBool(a->kw, b->kw, Py_EQ);
+        }
+    }
+
+    if (eq < 0) {
+        return NULL;
+    }
+
+    if (op == Py_EQ) {
+        res = eq ? Py_True : Py_False;
+    }
+    else {
+        res = eq ? Py_False : Py_True;
+    }
+
+    Py_INCREF(res);
+    return res;
+}
+
 static PyType_Slot partial_type_slots[] = {
     {Py_tp_dealloc, partial_dealloc},
     {Py_tp_repr, partial_repr},
@@ -486,6 +523,7 @@ static PyType_Slot partial_type_slots[] = {
     {Py_tp_doc, (void *)partial_doc},
     {Py_tp_traverse, partial_traverse},
     {Py_tp_clear, partial_clear},
+    {Py_tp_richcompare, partial_richcompare},
     {Py_tp_methods, partial_methods},
     {Py_tp_members, partial_memberlist},
     {Py_tp_getset, partial_getsetlist},