From 972e53865b79abddded73de352bf57d8ad0581ed Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Sun, 14 Oct 2018 19:37:27 +0300
Subject: [PATCH] bpo-34984: Improve error messages for bytes and bytearray
 constructors.

---
 Lib/test/test_bytes.py    |  2 ++
 Objects/bytearrayobject.c | 24 ++++++++++++++++++++----
 Objects/bytesobject.c     |  5 +++--
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index b7b48bfe17f6ee..4fadf1113b9e2b 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -152,6 +152,8 @@ class C:
         self.assertRaises(TypeError, self.type2test, [0.0])
         self.assertRaises(TypeError, self.type2test, [None])
         self.assertRaises(TypeError, self.type2test, [C()])
+        self.assertRaises(TypeError, self.type2test, encoding='ascii')
+        self.assertRaises(TypeError, self.type2test, errors='ignore')
         self.assertRaises(TypeError, self.type2test, 0, 'ascii')
         self.assertRaises(TypeError, self.type2test, b'', 'ascii')
         self.assertRaises(TypeError, self.type2test, 0, errors='ignore')
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 4e2bb603151b92..3072c7d046ec1b 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -784,7 +784,9 @@ bytearray_init(PyByteArrayObject *self, PyObject *args, PyObject *kwds)
     if (arg == NULL) {
         if (encoding != NULL || errors != NULL) {
             PyErr_SetString(PyExc_TypeError,
-                            "encoding or errors without sequence argument");
+                            encoding != NULL ?
+                            "encoding without a string argument" :
+                            "errors without a string argument");
             return -1;
         }
         return 0;
@@ -813,7 +815,9 @@ bytearray_init(PyByteArrayObject *self, PyObject *args, PyObject *kwds)
     /* 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");
+                        encoding != NULL ?
+                        "encoding without a string argument" :
+                        "errors without a string argument");
         return -1;
     }
 
@@ -861,8 +865,14 @@ bytearray_init(PyByteArrayObject *self, PyObject *args, PyObject *kwds)
 
     /* Get the iterator */
     it = PyObject_GetIter(arg);
-    if (it == NULL)
+    if (it == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            PyErr_Format(PyExc_TypeError,
+                         "cannot convert '%.200s' object to bytearray",
+                         arg->ob_type->tp_name);
+        }
         return -1;
+    }
     iternext = *Py_TYPE(it)->tp_iternext;
 
     /* Run the iterator to exhaustion */
@@ -1627,8 +1637,14 @@ bytearray_extend(PyByteArrayObject *self, PyObject *iterable_of_ints)
     }
 
     it = PyObject_GetIter(iterable_of_ints);
-    if (it == NULL)
+    if (it == NULL) {
+        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            PyErr_Format(PyExc_TypeError,
+                         "can't extend bytearray with %.100s",
+                         iterable_of_ints->ob_type->tp_name);
+        }
         return NULL;
+    }
 
     /* Try to determine the length of the argument. 32 is arbitrary. */
     buf_size = PyObject_LengthHint(iterable_of_ints, 32);
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index d51d1ba023c385..4aa78a08c28c4e 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -2537,8 +2537,9 @@ bytes_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     if (x == NULL) {
         if (encoding != NULL || errors != NULL) {
             PyErr_SetString(PyExc_TypeError,
-                            "encoding or errors without sequence "
-                            "argument");
+                            encoding != NULL ?
+                            "encoding without a string argument" :
+                            "errors without a string argument");
             return NULL;
         }
         return PyBytes_FromStringAndSize(NULL, 0);