#16518: Bring error messages in harmony with docs ("bytes-like object")

Some time ago we changed the docs to consistently use the term 'bytes-like
object' in all the contexts where bytes, bytearray, memoryview, etc are used.
This patch (by Ezio Melotti) completes that work by changing the error
messages that previously reported that certain types did "not support the
buffer interface" to instead say that a bytes-like object is required.  (The
glossary entry for bytes-like object references the discussion of the buffer
protocol in the docs.)

11 files changed, 30 insertions, 22 deletions

diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index 3e44aa2..4530a13 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -393,6 +393,12 @@ Changes in the Python API
   The *convert_charrefs* argument of :class:`~html.parser.HTMLParser` is
   now ``True`` by default (contributed by Berker Peksag in :issue:`21047`).
 
+* Although it is not formally part of the API, it is worth noting for porting
+  purposes (ie: fixing tests) that error messages that were previously of the
+  form "'sometype' does not support the buffer protocol" are now of the form "a
+  bytes-like object is required, not 'sometype'" (contributed by Ezio Melotti
+  in :issue:`16518`).
+
 Changes in the C API
 --------------------
 
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 98ee615..3f2057b 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -711,11 +711,11 @@ class GeneralModuleTests(unittest.TestCase):
         with self.assertRaises(TypeError) as cm:
             s.sendto('\u2620', sockname)
         self.assertEqual(str(cm.exception),
-                         "'str' does not support the buffer interface")
+                         "a bytes-like object is required, not 'str'")
         with self.assertRaises(TypeError) as cm:
             s.sendto(5j, sockname)
         self.assertEqual(str(cm.exception),
-                         "'complex' does not support the buffer interface")
+                         "a bytes-like object is required, not 'complex'")
         with self.assertRaises(TypeError) as cm:
             s.sendto(b'foo', None)
         self.assertIn('not NoneType',str(cm.exception))
@@ -723,11 +723,11 @@ class GeneralModuleTests(unittest.TestCase):
         with self.assertRaises(TypeError) as cm:
             s.sendto('\u2620', 0, sockname)
         self.assertEqual(str(cm.exception),
-                         "'str' does not support the buffer interface")
+                         "a bytes-like object is required, not 'str'")
         with self.assertRaises(TypeError) as cm:
             s.sendto(5j, 0, sockname)
         self.assertEqual(str(cm.exception),
-                         "'complex' does not support the buffer interface")
+                         "a bytes-like object is required, not 'complex'")
         with self.assertRaises(TypeError) as cm:
             s.sendto(b'foo', 0, None)
         self.assertIn('not NoneType', str(cm.exception))
diff --git a/Misc/NEWS b/Misc/NEWS
index c23186d..3aa92e8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@ Release date: TBA
 Core and Builtins
 -----------------
 
+- Issue #16518: Use 'bytes-like object required' in error messages that
+  previously used the far more cryptic "'x' does not support the buffer
+  protocol.
+
 - Issue #22470: Fixed integer overflow issues in "backslashreplace",
   "xmlcharrefreplace", and "surrogatepass" error handlers.
 
diff --git a/Modules/_operator.c b/Modules/_operator.c
index 9c5c0d2..8f524a6 100644
--- a/Modules/_operator.c
+++ b/Modules/_operator.c
@@ -241,7 +241,7 @@ PyDoc_STRVAR(compare_digest__doc__,
 "Return 'a == b'.  This function uses an approach designed to prevent\n"
 "timing analysis, making it appropriate for cryptography.\n"
 "a and b must both be of the same type: either str (ASCII only),\n"
-"or any type that supports the buffer protocol (e.g. bytes).\n"
+"or any bytes-like object.\n"
 "\n"
 "Note: If a and b are of different lengths, or if an error occurs,\n"
 "a timing attack could theoretically reveal information about the\n"
diff --git a/Objects/abstract.c b/Objects/abstract.c
index 177c34a..323c985 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -260,8 +260,7 @@ PyObject_AsCharBuffer(PyObject *obj,
     pb = obj->ob_type->tp_as_buffer;
     if (pb == NULL || pb->bf_getbuffer == NULL) {
         PyErr_SetString(PyExc_TypeError,
-                        "expected bytes, bytearray "
-                        "or buffer compatible object");
+                        "expected a bytes-like object");
         return -1;
     }
     if ((*pb->bf_getbuffer)(obj, &view, PyBUF_SIMPLE)) return -1;
@@ -306,7 +305,7 @@ int PyObject_AsReadBuffer(PyObject *obj,
     if (pb == NULL ||
         pb->bf_getbuffer == NULL) {
         PyErr_SetString(PyExc_TypeError,
-                        "expected an object with a buffer interface");
+                        "expected a bytes-like object");
         return -1;
     }
 
@@ -336,7 +335,7 @@ int PyObject_AsWriteBuffer(PyObject *obj,
         pb->bf_getbuffer == NULL ||
         ((*pb->bf_getbuffer)(obj, &view, PyBUF_WRITABLE) != 0)) {
         PyErr_SetString(PyExc_TypeError,
-                        "expected an object with a writable buffer interface");
+                        "expected a writable bytes-like object");
         return -1;
     }
 
@@ -355,7 +354,7 @@ PyObject_GetBuffer(PyObject *obj, Py_buffer *view, int flags)
 {
     if (!PyObject_CheckBuffer(obj)) {
         PyErr_Format(PyExc_TypeError,
-                     "'%.100s' does not support the buffer interface",
+                     "a bytes-like object is required, not '%.100s'",
                      Py_TYPE(obj)->tp_name);
         return -1;
     }
@@ -530,8 +529,8 @@ int PyObject_CopyData(PyObject *dest, PyObject *src)
     if (!PyObject_CheckBuffer(dest) ||
         !PyObject_CheckBuffer(src)) {
         PyErr_SetString(PyExc_TypeError,
-                        "both destination and source must have the "\
-                        "buffer interface");
+                        "both destination and source must be "\
+                        "bytes-like objects");
         return -1;
     }
 
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index f6f370d..84447bc 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -87,7 +87,7 @@ _getbuffer(PyObject *obj, Py_buffer *view)
     if (buffer == NULL || buffer->bf_getbuffer == NULL)
     {
         PyErr_Format(PyExc_TypeError,
-                     "Type %.100s doesn't support the buffer API",
+                     "a bytes-like object is required, not '%.100s'",
                      Py_TYPE(obj)->tp_name);
         return -1;
     }
diff --git a/Objects/bytes_methods.c b/Objects/bytes_methods.c
index 5314ab4..1cf20c9 100644
--- a/Objects/bytes_methods.c
+++ b/Objects/bytes_methods.c
@@ -371,7 +371,7 @@ _getbuffer(PyObject *obj, Py_buffer *view)
     if (buffer == NULL || buffer->bf_getbuffer == NULL)
     {
         PyErr_Format(PyExc_TypeError,
-                     "Type %.100s doesn't support the buffer API",
+                     "a bytes-like object is required, not '%.100s'",
                      Py_TYPE(obj)->tp_name);
         return -1;
     }
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 87c0a25..ff99f93 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -29,7 +29,7 @@ _getbuffer(PyObject *obj, Py_buffer *view)
     if (bufferprocs == NULL || bufferprocs->bf_getbuffer == NULL)
     {
         PyErr_Format(PyExc_TypeError,
-                     "Type %.100s doesn't support the buffer API",
+                     "a bytes-like object is required, not '%.100s'",
                      Py_TYPE(obj)->tp_name);
         return -1;
     }
diff --git a/Objects/longobject.c b/Objects/longobject.c
index bb2eb17..27bee50 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -4873,9 +4873,7 @@ PyDoc_STRVAR(long_from_bytes_doc,
 \n\
 Return the integer represented by the given array of bytes.\n\
 \n\
-The bytes argument must either support the buffer protocol or be an\n\
-iterable object producing bytes.  Bytes and bytearray are examples of\n\
-built-in objects that support the buffer protocol.\n\
+The bytes argument must be a bytes-like object (e.g. bytes or bytearray).\n\
 \n\
 The byteorder argument determines the byte order used to represent the\n\
 integer.  If byteorder is 'big', the most significant byte is at the\n\
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 5148ce6..935da04 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -792,7 +792,7 @@ PyMemoryView_FromObject(PyObject *v)
     }
 
     PyErr_Format(PyExc_TypeError,
-        "memoryview: %.200s object does not have the buffer interface",
+        "memoryview: a bytes-like object is required, not '%.200s'",
         Py_TYPE(v)->tp_name);
     return NULL;
 }
diff --git a/Python/getargs.c b/Python/getargs.c
index c749bb6..f7297da 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -1244,7 +1244,8 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
            supports it directly. */
         if (PyObject_GetBuffer(arg, (Py_buffer*)p, PyBUF_WRITABLE) < 0) {
             PyErr_Clear();
-            return converterr("read-write buffer", arg, msgbuf, bufsize);
+            return converterr("read-write bytes-like object",
+                              arg, msgbuf, bufsize);
         }
         if (!PyBuffer_IsContiguous((Py_buffer*)p, 'C')) {
             PyBuffer_Release((Py_buffer*)p);
@@ -1282,7 +1283,7 @@ convertbuffer(PyObject *arg, void **p, char **errmsg)
     *errmsg = NULL;
     *p = NULL;
     if (pb != NULL && pb->bf_releasebuffer != NULL) {
-        *errmsg = "read-only pinned buffer";
+        *errmsg = "read-only bytes-like object";
         return -1;
     }
 
@@ -1298,7 +1299,7 @@ static int
 getbuffer(PyObject *arg, Py_buffer *view, char **errmsg)
 {
     if (PyObject_GetBuffer(arg, view, PyBUF_SIMPLE) != 0) {
-        *errmsg = "bytes or buffer";
+        *errmsg = "bytes-like object";
         return -1;
     }
     if (!PyBuffer_IsContiguous(view, 'C')) {