pythongh-87901: os.popen: Remove the encoding argument

Author: methane

Doc/library/os.rst

@@ -3916,13 +3916,13 @@ written in Python, such as a mail server's external command delivery program.
    .. availability:: Unix.
 
 
-.. function:: popen(cmd, mode='r', buffering=-1, encoding=None)
+.. function:: popen(cmd, mode='r', buffering=-1)
 
    Open a pipe to or from command *cmd*.
    The return value is an open file object
    connected to the pipe, which can be read or written depending on whether *mode*
    is ``'r'`` (default) or ``'w'``.
-   The *buffering* and *encoding* arguments have the same meaning as
+   The *buffering* argument have the same meaning as
    the corresponding argument to the built-in :func:`open` function. The
    returned file object reads or writes text strings rather than bytes.
 
@@ -3945,8 +3945,14 @@ written in Python, such as a mail server's external command delivery program.
    documentation for more powerful ways to manage and communicate with
    subprocesses.
 
-   .. versionchanged:: 3.11
-      Added the *encoding* parameter.
+   .. note::
+      On Unix, the *cmd* argument is encoded with
+      :term:`file system encoding <filesystem encoding and error handler>`.
+      The returned file object connected to the pipe uses
+      :func:`locale.getpreferredencoding(False) <locale.getpreferredencoding>`_.
+      The :ref:`Python UTF-8 Mode <utf8-mode>` affects both encodings.
+
+      Use :class:`subprocess.Popen` to control encoding and many other options.
 
 
 .. function:: posix_spawn(path, argv, env, *, file_actions=None, \

Lib/os.py

@@ -974,15 +974,14 @@ def spawnlpe(mode, file, *args):
 # command in a shell can't be supported.
 if sys.platform != 'vxworks':
     # Supply os.popen()
-    def popen(cmd, mode="r", buffering=-1, encoding=None):
+    def popen(cmd, mode="r", buffering=-1):
         if not isinstance(cmd, str):
             raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))
         if mode not in ("r", "w"):
             raise ValueError("invalid mode %r" % mode)
         if buffering == 0 or buffering is None:
             raise ValueError("popen() does not support unbuffered streams")
-        import subprocess, io
-        encoding = io.text_encoding(encoding)
+        import subprocess
         if mode == "r":
             proc = subprocess.Popen(cmd,
                                     shell=True, text=True,