bpo-42431: Fix outdated bytes comments (GH-23458)

Also move definitions of internal macros F_LJUST etc to private header.
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 805707a..7cb2b14 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -13,10 +13,9 @@ class bytearray "PyByteArrayObject *" "&PyByteArray_Type"
 [clinic start generated code]*/
 /*[clinic end generated code: output=da39a3ee5e6b4b0d input=5535b77c37a119e0]*/
 
+/* For PyByteArray_AS_STRING(). */
 char _PyByteArray_empty_string[] = "";
 
-/* end nullbytes support */
-
 /* Helpers */
 
 static int
@@ -266,7 +265,7 @@ PyByteArray_Concat(PyObject *a, PyObject *b)
 
     result = (PyByteArrayObject *) \
         PyByteArray_FromStringAndSize(NULL, va.len + vb.len);
-    // result->ob_bytes is NULL if result is an empty string:
+    // result->ob_bytes is NULL if result is an empty bytearray:
     // if va.len + vb.len equals zero.
     if (result != NULL && result->ob_bytes != NULL) {
         memcpy(result->ob_bytes, va.buf, va.len);
@@ -1007,9 +1006,6 @@ bytearray_richcompare(PyObject *self, PyObject *other, int op)
     Py_buffer self_bytes, other_bytes;
     int cmp;
 
-    /* Bytes can be compared to anything that supports the (binary)
-       buffer API.  Except that a comparison with Unicode is always an
-       error, even if the comparison is for equality. */
     if (!PyObject_CheckBuffer(self) || !PyObject_CheckBuffer(other)) {
         if (PyUnicode_Check(self) || PyUnicode_Check(other)) {
             if (_Py_GetConfig()->bytes_warning && (op == Py_EQ || op == Py_NE)) {
@@ -1021,6 +1017,7 @@ bytearray_richcompare(PyObject *self, PyObject *other, int op)
         Py_RETURN_NOTIMPLEMENTED;
     }
 
+    /* Bytearrays can be compared to anything that supports the buffer API. */
     if (PyObject_GetBuffer(self, &self_bytes, PyBUF_SIMPLE) != 0) {
         PyErr_Clear();
         Py_RETURN_NOTIMPLEMENTED;
@@ -1328,7 +1325,7 @@ bytearray_translate_impl(PyByteArrayObject *self, PyObject *table,
         if (trans_table[c] != -1)
             *output++ = (char)trans_table[c];
     }
-    /* Fix the size of the resulting string */
+    /* Fix the size of the resulting bytearray */
     if (inlen > 0)
         if (PyByteArray_Resize(result, output - output_start) < 0) {
             Py_CLEAR(result);
@@ -2083,7 +2080,7 @@ bytearray.hex
         How many bytes between separators.  Positive values count from the
         right, negative values count from the left.
 
-Create a str of hexadecimal numbers from a bytearray object.
+Create a string of hexadecimal numbers from a bytearray object.
 
 Example:
 >>> value = bytearray([0xb9, 0x01, 0xef])
@@ -2099,7 +2096,7 @@ Create a str of hexadecimal numbers from a bytearray object.
 
 static PyObject *
 bytearray_hex_impl(PyByteArrayObject *self, PyObject *sep, int bytes_per_sep)
-/*[clinic end generated code: output=29c4e5ef72c565a0 input=814c15830ac8c4b5]*/
+/*[clinic end generated code: output=29c4e5ef72c565a0 input=808667e49bcccb54]*/
 {
     char* argbuf = PyByteArray_AS_STRING(self);
     Py_ssize_t arglen = PyByteArray_GET_SIZE(self);
@@ -2358,7 +2355,7 @@ PyTypeObject PyByteArray_Type = {
     PyObject_Del,                       /* tp_free */
 };
 
-/*********************** Bytes Iterator ****************************/
+/*********************** Bytearray Iterator ****************************/
 
 typedef struct {
     PyObject_HEAD
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 13216b9..ccabbdc 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -5,6 +5,7 @@
 #include "Python.h"
 #include "pycore_abstract.h"      // _PyIndex_Check()
 #include "pycore_bytes_methods.h" // _Py_bytes_startswith()
+#include "pycore_format.h"        // F_LJUST
 #include "pycore_initconfig.h"    // _PyStatus_OK()
 #include "pycore_object.h"        // _PyObject_GC_TRACK
 #include "pycore_pymem.h"         // PYMEM_CLEANBYTE
@@ -21,11 +22,11 @@ class bytes "PyBytesObject *" "&PyBytes_Type"
 
 _Py_IDENTIFIER(__bytes__);
 
-/* PyBytesObject_SIZE gives the basic size of a string; any memory allocation
-   for a string of length n should request PyBytesObject_SIZE + n bytes.
+/* PyBytesObject_SIZE gives the basic size of a bytes object; any memory allocation
+   for a bytes object of length n should request PyBytesObject_SIZE + n bytes.
 
    Using PyBytesObject_SIZE instead of sizeof(PyBytesObject) saves
-   3 bytes per string allocation on a typical system.
+   3 or 7 bytes per bytes object allocation on a typical system.
 */
 #define PyBytesObject_SIZE (offsetof(PyBytesObject, ob_sval) + 1)
 
@@ -439,19 +440,6 @@ getnextarg(PyObject *args, Py_ssize_t arglen, Py_ssize_t *p_argidx)
     return NULL;
 }
 
-/* Format codes
- * F_LJUST      '-'
- * F_SIGN       '+'
- * F_BLANK      ' '
- * F_ALT        '#'
- * F_ZERO       '0'
- */
-#define F_LJUST (1<<0)
-#define F_SIGN  (1<<1)
-#define F_BLANK (1<<2)
-#define F_ALT   (1<<3)
-#define F_ZERO  (1<<4)
-
 /* Returns a new reference to a PyBytes object, or NULL on failure. */
 
 static char*
@@ -1560,7 +1548,7 @@ bytes_richcompare(PyBytesObject *a, PyBytesObject *b, int op)
         case Py_EQ:
         case Py_LE:
         case Py_GE:
-            /* a string is equal to itself */
+            /* a byte string is equal to itself */
             Py_RETURN_TRUE;
         case Py_NE:
         case Py_LT:
@@ -2149,7 +2137,7 @@ bytes_translate_impl(PyBytesObject *self, PyObject *table,
         Py_INCREF(input_obj);
         return input_obj;
     }
-    /* Fix the size of the resulting string */
+    /* Fix the size of the resulting byte string */
     if (inlen > 0)
         _PyBytes_Resize(&result, output - output_start);
     return result;
@@ -2453,7 +2441,7 @@ bytes.hex
         How many bytes between separators.  Positive values count from the
         right, negative values count from the left.
 
-Create a str of hexadecimal numbers from a bytes object.
+Create a string of hexadecimal numbers from a bytes object.
 
 Example:
 >>> value = b'\xb9\x01\xef'
@@ -2469,7 +2457,7 @@ Create a str of hexadecimal numbers from a bytes object.
 
 static PyObject *
 bytes_hex_impl(PyBytesObject *self, PyObject *sep, int bytes_per_sep)
-/*[clinic end generated code: output=1f134da504064139 input=f1238d3455990218]*/
+/*[clinic end generated code: output=1f134da504064139 input=1a21282b1f1ae595]*/
 {
     const char *argbuf = PyBytes_AS_STRING(self);
     Py_ssize_t arglen = PyBytes_GET_SIZE(self);
@@ -2771,7 +2759,7 @@ _PyBytes_FromIterator(PyObject *it, PyObject *x)
     Py_ssize_t i, size;
     _PyBytesWriter writer;
 
-    /* For iterator version, create a string object and resize as needed */
+    /* For iterator version, create a bytes object and resize as needed */
     size = PyObject_LengthHint(x, 64);
     if (size == -1 && PyErr_Occurred())
         return NULL;
diff --git a/Objects/clinic/bytearrayobject.c.h b/Objects/clinic/bytearrayobject.c.h
index 3452b24..1e3f197 100644
--- a/Objects/clinic/bytearrayobject.c.h
+++ b/Objects/clinic/bytearrayobject.c.h
@@ -990,7 +990,7 @@ PyDoc_STRVAR(bytearray_hex__doc__,
 "hex($self, /, sep=<unrepresentable>, bytes_per_sep=1)\n"
 "--\n"
 "\n"
-"Create a str of hexadecimal numbers from a bytearray object.\n"
+"Create a string of hexadecimal numbers from a bytearray object.\n"
 "\n"
 "  sep\n"
 "    An optional single character or byte to separate hex bytes.\n"
@@ -1120,4 +1120,4 @@ bytearray_sizeof(PyByteArrayObject *self, PyObject *Py_UNUSED(ignored))
 {
     return bytearray_sizeof_impl(self);
 }
-/*[clinic end generated code: output=47cd9ad3fdc3ac0c input=a9049054013a1b77]*/
+/*[clinic end generated code: output=a82659f581e55629 input=a9049054013a1b77]*/
diff --git a/Objects/clinic/bytesobject.c.h b/Objects/clinic/bytesobject.c.h
index 27ac6b1..9e365ce 100644
--- a/Objects/clinic/bytesobject.c.h
+++ b/Objects/clinic/bytesobject.c.h
@@ -750,7 +750,7 @@ PyDoc_STRVAR(bytes_hex__doc__,
 "hex($self, /, sep=<unrepresentable>, bytes_per_sep=1)\n"
 "--\n"
 "\n"
-"Create a str of hexadecimal numbers from a bytes object.\n"
+"Create a string of hexadecimal numbers from a bytes object.\n"
 "\n"
 "  sep\n"
 "    An optional single character or byte to separate hex bytes.\n"
@@ -878,4 +878,4 @@ bytes_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=6101b417d6a6a717 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b3f0ec2753246b9c input=a9049054013a1b77]*/
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f6473c0..4093555 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -42,6 +42,7 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include "Python.h"
 #include "pycore_abstract.h"      // _PyIndex_Check()
 #include "pycore_bytes_methods.h" // _Py_bytes_lower()
+#include "pycore_format.h"        // F_LJUST
 #include "pycore_initconfig.h"    // _PyStatus_OK()
 #include "pycore_interp.h"        // PyInterpreterState.fs_codec
 #include "pycore_object.h"        // _PyObject_GC_TRACK()