gh-85308: argparse: Use filesystem encoding for arguments file (GH-93277)

1 files changed, 10 insertions, 1 deletions

diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 0e62e99d70..b2fa0b3c23 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -562,7 +562,7 @@ at the command line.  If the ``fromfile_prefix_chars=`` argument is given to the
 specified characters will be treated as files, and will be replaced by the
 arguments they contain.  For example::
 
-   >>> with open('args.txt', 'w') as fp:
+   >>> with open('args.txt', 'w', encoding=sys.getfilesystemencoding()) as fp:
    ...     fp.write('-f\nbar')
    >>> parser = argparse.ArgumentParser(fromfile_prefix_chars='@')
    >>> parser.add_argument('-f')
@@ -575,9 +575,18 @@ were in the same place as the original file referencing argument on the command
 line.  So in the example above, the expression ``['-f', 'foo', '@args.txt']``
 is considered equivalent to the expression ``['-f', 'foo', '-f', 'bar']``.
 
+:class:`ArgumentParser` uses :term:`filesystem encoding and error handler`
+to read the file containing arguments.
+
 The ``fromfile_prefix_chars=`` argument defaults to ``None``, meaning that
 arguments will never be treated as file references.
 
+.. versionchanged:: 3.12
+   :class:`ArgumentParser` changed encoding and errors to read arguments files
+   from default (e.g. :func:`locale.getpreferredencoding(False)` and
+   ``"strict"``) to :term:`filesystem encoding and error handler`.
+   Arguments file should be encoded in UTF-8 instead of ANSI Codepage on Windows.
+
 
 argument_default
 ^^^^^^^^^^^^^^^^