gh-123446: Fix empty function names in `TypeError`s in `typeobject` (#123470)

3 files changed, 63 insertions, 11 deletions

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index b0f8631..9d15ab3 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4021,6 +4021,20 @@ class ClassPropertiesAndMethods(unittest.TestCase):
             y = x ** 2
         self.assertIn('unsupported operand type(s) for **', str(cm.exception))
 
+    def test_pow_wrapper_error_messages(self):
+        self.assertRaisesRegex(TypeError,
+                               'expected 1 or 2 arguments, got 0',
+                               int().__pow__)
+        self.assertRaisesRegex(TypeError,
+                               'expected 1 or 2 arguments, got 3',
+                               int().__pow__, 1, 2, 3)
+        self.assertRaisesRegex(TypeError,
+                               'expected 1 or 2 arguments, got 0',
+                               int().__rpow__)
+        self.assertRaisesRegex(TypeError,
+                               'expected 1 or 2 arguments, got 3',
+                               int().__rpow__, 1, 2, 3)
+
     def test_mutable_bases(self):
         # Testing mutable bases...
 
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2024-08-29-13-18-18.gh-issue-123446.KWDrgq.rst b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-29-13-18-18.gh-issue-123446.KWDrgq.rst
new file mode 100644
index 0000000..704bde9
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2024-08-29-13-18-18.gh-issue-123446.KWDrgq.rst
@@ -0,0 +1,2 @@
+Fix empty function name in :exc:`TypeError` when builtin magic methods are
+used without the required args.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c3a8fb5..d9c6b99 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -8678,6 +8678,27 @@ check_num_args(PyObject *ob, int n)
     return 0;
 }
 
+static Py_ssize_t
+check_pow_args(PyObject *ob)
+{
+    // Returns the argument count on success or `-1` on error.
+    int min = 1;
+    int max = 2;
+    if (!PyTuple_CheckExact(ob)) {
+        PyErr_SetString(PyExc_SystemError,
+            "PyArg_UnpackTuple() argument list is not a tuple");
+        return -1;
+    }
+    Py_ssize_t size = PyTuple_GET_SIZE(ob);
+    if (size >= min && size <= max) {
+        return size;
+    }
+    PyErr_Format(
+        PyExc_TypeError,
+        "expected %d or %d arguments, got %zd", min, max, PyTuple_GET_SIZE(ob));
+    return -1;
+}
+
 /* Generic wrappers for overloadable 'operators' such as __getitem__ */
 
 /* There's a wrapper *function* for each distinct function typedef used
@@ -8759,8 +8780,15 @@ wrap_ternaryfunc(PyObject *self, PyObject *args, void *wrapped)
 
     /* Note: This wrapper only works for __pow__() */
 
-    if (!PyArg_UnpackTuple(args, "", 1, 2, &other, &third))
+    Py_ssize_t size = check_pow_args(args);
+    if (size == -1) {
         return NULL;
+    }
+    other = PyTuple_GET_ITEM(args, 0);
+    if (size == 2) {
+       third = PyTuple_GET_ITEM(args, 1);
+    }
+
     return (*func)(self, other, third);
 }
 
@@ -8771,10 +8799,17 @@ wrap_ternaryfunc_r(PyObject *self, PyObject *args, void *wrapped)
     PyObject *other;
     PyObject *third = Py_None;
 
-    /* Note: This wrapper only works for __pow__() */
+    /* Note: This wrapper only works for __rpow__() */
 
-    if (!PyArg_UnpackTuple(args, "", 1, 2, &other, &third))
+    Py_ssize_t size = check_pow_args(args);
+    if (size == -1) {
         return NULL;
+    }
+    other = PyTuple_GET_ITEM(args, 0);
+    if (size == 2) {
+       third = PyTuple_GET_ITEM(args, 1);
+    }
+
     return (*func)(other, self, third);
 }
 
@@ -8795,8 +8830,9 @@ wrap_indexargfunc(PyObject *self, PyObject *args, void *wrapped)
     PyObject* o;
     Py_ssize_t i;
 
-    if (!PyArg_UnpackTuple(args, "", 1, 1, &o))
+    if (!check_num_args(args, 1))
         return NULL;
+    o = PyTuple_GET_ITEM(args, 0);
     i = PyNumber_AsSsize_t(o, PyExc_OverflowError);
     if (i == -1 && PyErr_Occurred())
         return NULL;
@@ -8852,7 +8888,7 @@ wrap_sq_setitem(PyObject *self, PyObject *args, void *wrapped)
     int res;
     PyObject *arg, *value;
 
-    if (!PyArg_UnpackTuple(args, "", 2, 2, &arg, &value))
+    if (!PyArg_UnpackTuple(args, "__setitem__", 2, 2, &arg, &value))
         return NULL;
     i = getindex(self, arg);
     if (i == -1 && PyErr_Occurred())
@@ -8908,7 +8944,7 @@ wrap_objobjargproc(PyObject *self, PyObject *args, void *wrapped)
     int res;
     PyObject *key, *value;
 
-    if (!PyArg_UnpackTuple(args, "", 2, 2, &key, &value))
+    if (!PyArg_UnpackTuple(args, "__setitem__", 2, 2, &key, &value))
         return NULL;
     res = (*func)(self, key, value);
     if (res == -1 && PyErr_Occurred())
@@ -9005,7 +9041,7 @@ wrap_setattr(PyObject *self, PyObject *args, void *wrapped)
     int res;
     PyObject *name, *value;
 
-    if (!PyArg_UnpackTuple(args, "", 2, 2, &name, &value))
+    if (!PyArg_UnpackTuple(args, "__setattr__", 2, 2, &name, &value))
         return NULL;
     if (!hackcheck(self, func, "__setattr__"))
         return NULL;
@@ -9115,7 +9151,7 @@ wrap_descr_get(PyObject *self, PyObject *args, void *wrapped)
     PyObject *obj;
     PyObject *type = NULL;
 
-    if (!PyArg_UnpackTuple(args, "", 1, 2, &obj, &type))
+    if (!PyArg_UnpackTuple(args, "__get__", 1, 2, &obj, &type))
         return NULL;
     if (obj == Py_None)
         obj = NULL;
@@ -9136,7 +9172,7 @@ wrap_descr_set(PyObject *self, PyObject *args, void *wrapped)
     PyObject *obj, *value;
     int ret;
 
-    if (!PyArg_UnpackTuple(args, "", 2, 2, &obj, &value))
+    if (!PyArg_UnpackTuple(args, "__set__", 2, 2, &obj, &value))
         return NULL;
     ret = (*func)(self, obj, value);
     if (ret < 0)
@@ -9165,7 +9201,7 @@ wrap_buffer(PyObject *self, PyObject *args, void *wrapped)
 {
     PyObject *arg = NULL;
 
-    if (!PyArg_UnpackTuple(args, "", 1, 1, &arg)) {
+    if (!PyArg_UnpackTuple(args, "__buffer__", 1, 1, &arg)) {
         return NULL;
     }
     Py_ssize_t flags = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
@@ -9186,7 +9222,7 @@ static PyObject *
 wrap_releasebuffer(PyObject *self, PyObject *args, void *wrapped)
 {
     PyObject *arg = NULL;
-    if (!PyArg_UnpackTuple(args, "", 1, 1, &arg)) {
+    if (!PyArg_UnpackTuple(args, "__release_buffer__", 1, 1, &arg)) {
         return NULL;
     }
     if (!PyMemoryView_Check(arg)) {