Issue #20335: bytes constructor now raises TypeError when encoding or errors

is specified with non-string argument.  Based on patch by Renaud Blanch.

Lib/test/test_bytes.py

@@ -100,6 +100,14 @@ class BaseBytesTest:
         self.assertRaises(TypeError, self.type2test, [0.0])
         self.assertRaises(TypeError, self.type2test, [None])
         self.assertRaises(TypeError, self.type2test, [C()])
+        self.assertRaises(TypeError, self.type2test, 0, 'ascii')
+        self.assertRaises(TypeError, self.type2test, b'', 'ascii')
+        self.assertRaises(TypeError, self.type2test, 0, errors='ignore')
+        self.assertRaises(TypeError, self.type2test, b'', errors='ignore')
+        self.assertRaises(TypeError, self.type2test, '')
+        self.assertRaises(TypeError, self.type2test, '', errors='ignore')
+        self.assertRaises(TypeError, self.type2test, '', b'ascii')
+        self.assertRaises(TypeError, self.type2test, '', 'ascii', b'ignore')
 
     def test_constructor_value_errors(self):
         self.assertRaises(ValueError, self.type2test, [-1])

Misc/NEWS

@@ -11,6 +11,9 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #20335: bytes constructor now raises TypeError when encoding or errors
+  is specified with non-string argument.  Based on patch by Renaud Blanch.
+
 - Issue #22335: Fix crash when trying to enlarge a bytearray to 0x7fffffff
   bytes on a 32-bit platform.
 

Objects/bytesobject.c

@@ -2503,6 +2503,13 @@ bytes_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         return new;
     }
 
+    /* If it's not unicode, there can't be encoding or errors */
+    if (encoding != NULL || errors != NULL) {
+        PyErr_SetString(PyExc_TypeError,
+            "encoding or errors without a string argument");
+        return NULL;
+    }
+
     /* We'd like to call PyObject_Bytes here, but we need to check for an
        integer argument before deferring to PyBytes_FromObject, something
        PyObject_Bytes doesn't do. */
@@ -2544,13 +2551,6 @@ bytes_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         return new;
     }
 
-    /* If it's not unicode, there can't be encoding or errors */
-    if (encoding != NULL || errors != NULL) {
-        PyErr_SetString(PyExc_TypeError,
-            "encoding or errors without a string argument");
-        return NULL;
-    }
-
     return PyBytes_FromObject(x);
 }