bpo-37330: open() no longer accept 'U' in file mode (GH-16959)
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.diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index f071057..ec6a053 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -197,6 +197,9 @@
*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:: 3.9
+ 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 f5e5280..8870c17 100644
--- a/Doc/library/fileinput.rst
+++ b/Doc/library/fileinput.rst
@@ -148,8 +148,8 @@
The sequence must be accessed in strictly sequential order; random access
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'``.
+ With *mode* you can specify which file mode will be passed to :func:`open`.
+ It must be ``'r'`` or ``'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
@@ -166,15 +166,14 @@
.. 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.
.. versionchanged:: 3.8
The keyword parameter *mode* and *openhook* are now keyword-only.
+ .. versionchanged:: 3.9
+ The ``'rU'`` and ``'U'`` modes have been removed.
**Optional in-place filtering:** if the keyword argument ``inplace=True`` is
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 28d9c7b..acf922d 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1085,12 +1085,6 @@
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 behaviour
- 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
@@ -1247,10 +1241,6 @@
* The file is now non-inheritable.
- .. deprecated-removed:: 3.4 4.0
-
- The ``'U'`` mode.
-
.. versionchanged::
3.5
@@ -1266,6 +1256,10 @@
* On Windows, opening a console buffer may return a subclass of
:class:`io.RawIOBase` other than :class:`io.FileIO`.
+ .. versionchanged:: 3.9
+ The ``'U'`` mode has been removed.
+
+
.. function:: ord(c)
Given a string representing one Unicode character, return an integer
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 886c555..bca2229 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -284,6 +284,14 @@
Changes in the Python API
-------------------------
+* :func:`open`, :func:`io.open`, :func:`codecs.open` and
+ :class:`fileinput.FileInput` no longer accept ``'U'`` ("universal newline")
+ in the file mode. This flag was deprecated since Python 3.3. In Python 3, the
+ "universal newline" is used by default when a file is open in text mode. The
+ :ref:`newline parameter <open-newline-parameter>` of :func:`open` controls
+ how universal newlines works.
+ (Contributed by Victor Stinner in :issue:`37330`.)
+
* :func:`__import__` and :func:`importlib.util.resolve_name` now raise
:exc:`ImportError` where it previously raised :exc:`ValueError`. Callers
catching the specific exception type and supporting both Python 3.9 and