Apply suggestions from @picnixz in #129844

Author: lordmauve

Doc/library/stdtypes.rst

@@ -2738,7 +2738,7 @@ data and are closely related to string objects in a variety of other ways.
          :meth:`bytes.fromhex` now skips all ASCII whitespace in the string,
          not just spaces.
 
-      .. versionchanged:: 3.14
+      .. versionchanged:: next
          :meth:`bytes.fromhex` now accepts an ASCII :class:`bytes` object as
          input.
 
@@ -2828,7 +2828,7 @@ objects.
          :meth:`bytearray.fromhex` now skips all ASCII whitespace in the string,
          not just spaces.
 
-      .. versionchanged:: 3.14
+      .. versionchanged:: next
          :meth:`bytearray.fromhex` now accepts an ASCII :class:`bytes` object as
          input.
 

Doc/whatsnew/3.14.rst

@@ -278,6 +278,10 @@ Other language changes
   making it a :term:`generic type`.
   (Contributed by Brian Schubert in :gh:`126012`.)
 
+* The :func:`bytes.fromhex` and :func:`bytearray.fromhex` methods now accept
+  ASCII :class:`bytes` and :class:`bytearray` objects.
+  (Contributed by Daniel Pope in :gh:`129349`.)
+
 * ``\B`` in :mod:`regular expression <re>` now matches empty input string.
   Now it is always the opposite of ``\b``.
   (Contributed by Serhiy Storchaka in :gh:`124130`.)

Lib/test/test_bytes.py

@@ -446,6 +446,7 @@ def test_fromhex(self):
 
         # check that ASCII whitespace is ignored
         self.assertEqual(self.type2test.fromhex(' 1A\n2B\t30\v'), b)
+        self.assertEqual(self.type2test.fromhex(b' 1A\n2B\t30\v'), b)
         for c in "\x09\x0A\x0B\x0C\x0D\x20":
             self.assertEqual(self.type2test.fromhex(c), self.type2test())
         for c in "\x1C\x1D\x1E\x1F\x85\xa0\u2000\u2002\u2028":
@@ -457,6 +458,10 @@ def test_fromhex(self):
             self.type2test.fromhex(bytearray(b' 012abc')),
             b'\x01\x2a\xbc',
         )
+        # Invalid bytes are rejected
+        for u8 in b"\0\x1C\x1D\x1E\x1F\x85\xa0":
+            b = bytes([30, 31, u8])
+            self.assertRaises(ValueError, self.type2test.fromhex, b)
 
         self.assertEqual(self.type2test.fromhex('0000'), b'\0\0')
         self.assertRaises(ValueError, self.type2test.fromhex, 'a')

Misc/NEWS.d/next/Core_and_Builtins/2025-02-08-09-55-33.gh-issue-129349.PkcG-l.rst

@@ -1 +1,2 @@
-``bytes.fromhex()``/``bytearray.fromhex()`` now accept ASCII ``bytes``.
+:meth:`bytes.fromhex` and :meth:`bytearray.fromhex()` now accepts ASCII
+:class:`bytes` objects.

Objects/bytesobject.c

@@ -2535,16 +2535,19 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
 
         assert(PyUnicode_KIND(string) == PyUnicode_1BYTE_KIND);
         str = start = PyUnicode_1BYTE_DATA(string);
-    } else if (PyBytes_Check(string)) {
+    }
+    else if (PyBytes_Check(string)) {
         hexlen = PyBytes_GET_SIZE(string);
-        str = start = (Py_UCS1 *) PyBytes_AS_STRING(string);
-    } else if (PyByteArray_Check(string)) {
+        str = start = (Py_UCS1 *)PyBytes_AS_STRING(string);
+    }
+    else if (PyByteArray_Check(string)) {
         hexlen = PyByteArray_GET_SIZE(string);
-        str = start = (Py_UCS1 *) PyByteArray_AS_STRING(string);
-    } else {
+        str = start = (Py_UCS1 *)PyByteArray_AS_STRING(string);
+    }
+    else {
         PyErr_Format(PyExc_TypeError,
-                        "fromhex() argument must be str or bytes, not %s",
-                        Py_TYPE(string)->tp_name);
+                     "fromhex() argument must be str or bytes, not %T",
+                     string);
         return NULL;
     }