bpo-39200: Correct the error message for min/max builtin function (GH-17814)

Correct the error message when calling the min() or max() with
no arguments.

3 files changed, 21 insertions, 4 deletions

diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 6a88454289..5c553a92b9 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -949,7 +949,12 @@ class BuiltinTest(unittest.TestCase):
         self.assertEqual(max(1, 2.0, 3), 3)
         self.assertEqual(max(1.0, 2, 3), 3)
 
-        self.assertRaises(TypeError, max)
+        with self.assertRaisesRegex(
+            TypeError,
+            'max expected at least 1 argument, got 0'
+        ):
+            max()
+
         self.assertRaises(TypeError, max, 42)
         self.assertRaises(ValueError, max, ())
         class BadSeq:
@@ -1003,7 +1008,12 @@ class BuiltinTest(unittest.TestCase):
         self.assertEqual(min(1, 2.0, 3), 1)
         self.assertEqual(min(1.0, 2, 3), 1.0)
 
-        self.assertRaises(TypeError, min)
+        with self.assertRaisesRegex(
+            TypeError,
+            'min expected at least 1 argument, got 0'
+        ):
+            min()
+
         self.assertRaises(TypeError, min, 42)
         self.assertRaises(ValueError, min, ())
         class BadSeq:
diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-01-04-01-14-32.bpo-39200.8Z9DYp.rst b/Misc/NEWS.d/next/Core and Builtins/2020-01-04-01-14-32.bpo-39200.8Z9DYp.rst
new file mode 100644
index 0000000000..71e4072099
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2020-01-04-01-14-32.bpo-39200.8Z9DYp.rst
@@ -0,0 +1,2 @@
+Correct the error message when calling the :func:`min` or :func:`max` with
+no arguments. Patch by Dong-hee Na.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 34267685be..4f833c1f46 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1589,10 +1589,15 @@ min_max(PyObject *args, PyObject *kwds, int op)
     const int positional = PyTuple_Size(args) > 1;
     int ret;
 
-    if (positional)
+    if (positional) {
         v = args;
-    else if (!PyArg_UnpackTuple(args, name, 1, 1, &v))
+    }
+    else if (!PyArg_UnpackTuple(args, name, 1, 1, &v)) {
+        if (PyExceptionClass_Check(PyExc_TypeError)) {
+            PyErr_Format(PyExc_TypeError, "%s expected at least 1 argument, got 0", name);
+        }
         return NULL;
+    }
 
     emptytuple = PyTuple_New(0);
     if (emptytuple == NULL)