bpo-37330: open() no longer accept 'U' in file mode (GH-28118)

open(), io.open(), codecs.open() and fileinput.FileInput no longer
accept "U" ("universal newline") in the file mode. This flag was
deprecated since Python 3.3.

3 files changed, 14 insertions, 22 deletions

diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index 0dcd88f9fd..9ea689acd8 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -204,6 +204,9 @@ wider range of codecs when working with binary files:
    *buffering* has the same meaning as for the built-in :func:`open` function.
    It defaults to -1 which means that the default buffer size will be used.
 
+   .. versionchanged:: 3.11
+      The ``'U'`` mode has been removed.
+
 
 .. function:: EncodedFile(file, data_encoding, file_encoding=None, errors='strict')
 
diff --git a/Doc/library/fileinput.rst b/Doc/library/fileinput.rst
index 3880ed3d2b..9f7802dd45 100644
--- a/Doc/library/fileinput.rst
+++ b/Doc/library/fileinput.rst
@@ -153,7 +153,7 @@ available for subclassing as well:
    and :meth:`~io.TextIOBase.readline` cannot be mixed.
 
    With *mode* you can specify which file mode will be passed to :func:`open`. It
-   must be one of ``'r'``, ``'rU'``, ``'U'`` and ``'rb'``.
+   must be one of ``'r'`` and ``'rb'``.
 
    The *openhook*, when given, must be a function that takes two arguments,
    *filename* and *mode*, and returns an accordingly opened file-like object. You
@@ -171,9 +171,6 @@ available for subclassing as well:
    .. versionchanged:: 3.2
       Can be used as a context manager.
 
-   .. deprecated:: 3.4
-      The ``'rU'`` and ``'U'`` modes.
-
    .. deprecated:: 3.8
       Support for :meth:`__getitem__` method is deprecated.
 
@@ -183,6 +180,9 @@ available for subclassing as well:
    .. versionchanged:: 3.10
       The keyword-only parameter *encoding* and *errors* are added.
 
+   .. versionchanged:: 3.11
+      The ``'rU'`` and ``'U'`` modes have been removed.
+
 
 **Optional in-place filtering:** if the keyword argument ``inplace=True`` is
 passed to :func:`fileinput.input` or to the :class:`FileInput` constructor, the
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 9629acec2b..a8fc7023d1 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1156,12 +1156,6 @@ are always available.  They are listed here in alphabetical order.
    first decoded using a platform-dependent encoding or using the specified
    *encoding* if given.
 
-   There is an additional mode character permitted, ``'U'``, which no longer
-   has any effect, and is considered deprecated. It previously enabled
-   :term:`universal newlines` in text mode, which became the default behavior
-   in Python 3.0. Refer to the documentation of the
-   :ref:`newline <open-newline-parameter>` parameter for further details.
-
    .. note::
 
       Python doesn't depend on the underlying operating system's notion of text
@@ -1304,8 +1298,7 @@ are always available.  They are listed here in alphabetical order.
    The ``mode`` and ``flags`` arguments may have been modified or inferred from
    the original call.
 
-   .. versionchanged::
-      3.3
+   .. versionchanged:: 3.3
 
          * The *opener* parameter was added.
          * The ``'x'`` mode was added.
@@ -1313,30 +1306,26 @@ are always available.  They are listed here in alphabetical order.
          * :exc:`FileExistsError` is now raised if the file opened in exclusive
            creation mode (``'x'``) already exists.
 
-   .. versionchanged::
-      3.4
+   .. versionchanged:: 3.4
 
          * The file is now non-inheritable.
 
-   .. deprecated-removed:: 3.4 3.10
-
-      The ``'U'`` mode.
-
-   .. versionchanged::
-      3.5
+   .. versionchanged:: 3.5
 
          * If the system call is interrupted and the signal handler does not raise an
            exception, the function now retries the system call instead of raising an
            :exc:`InterruptedError` exception (see :pep:`475` for the rationale).
          * The ``'namereplace'`` error handler was added.
 
-   .. versionchanged::
-      3.6
+   .. versionchanged:: 3.6
 
          * Support added to accept objects implementing :class:`os.PathLike`.
          * On Windows, opening a console buffer may return a subclass of
            :class:`io.RawIOBase` other than :class:`io.FileIO`.
 
+   .. versionchanged:: 3.11
+      The ``'U'`` mode has been removed.
+
 .. function:: ord(c)
 
    Given a string representing one Unicode character, return an integer