Issue #8784: Set tarfile default encoding to 'utf-8' on Windows.

Note: file system encoding cannot be None anymore (since r81190, issue #8610).

Doc/library/tarfile.rst

@@ -185,8 +185,8 @@ The following variables are available on module level:
 
 .. data:: ENCODING
 
-   The default character encoding i.e. the value from either
-   :func:`sys.getfilesystemencoding` or :func:`sys.getdefaultencoding`.
+   The default character encoding: ``'utf-8'`` on Windows,
+   :func:`sys.getfilesystemencoding` otherwise.
 
 
 .. seealso::

Lib/tarfile.py

@@ -159,9 +159,10 @@ TOEXEC  = 0o001           # execute/search by other
 #---------------------------------------------------------
 # initialization
 #---------------------------------------------------------
-ENCODING = sys.getfilesystemencoding()
-if ENCODING is None:
-    ENCODING = "ascii"
+if os.name in ("nt", "ce"):
+    ENCODING = "utf-8"
+else:
+    ENCODING = sys.getfilesystemencoding()
 
 #---------------------------------------------------------
 # Some useful functions

Misc/NEWS

@@ -421,6 +421,8 @@ C-API
 Library
 -------
 
+- Issue #8784: Set tarfile default encoding to 'utf-8' on Windows.
+
 - Issue #8966: If a ctypes structure field is an array of c_char, convert its
   value to bytes instead of str (as done for c_char and c_char_p).