address review: improve message in loghelper()

Author: skirpichev

Lib/test/test_math.py

@@ -2533,7 +2533,7 @@ def test_exception_messages(self):
             math.log(x)
         x = -123
         with self.assertRaisesRegex(ValueError,
-                                    f"expected a positive input"):
+                                    f"expected a positive input, got {x}"):
             math.log(x)
         with self.assertRaisesRegex(ValueError,
                                     f"expected a float or nonnegative integer, got {x}"):

Modules/mathmodule.c

@@ -2232,8 +2232,8 @@ loghelper(PyObject* arg, double (*func)(double))
 
         /* Negative or zero inputs give a ValueError. */
         if (!_PyLong_IsPositive((PyLongObject *)arg)) {
-            PyErr_SetString(PyExc_ValueError,
-                            "expected a positive input");
+            PyErr_Format(PyExc_ValueError,
+                         "expected a positive input, got %S", arg);
             return NULL;
         }