remove deprecated safe_join

CHANGES.rst

@@ -13,6 +13,8 @@ Unreleased
     -   ``config.from_json`` is replaced by
         ``config.from_file(name, load=json.load)``.
     -   ``json`` functions no longer take an ``encoding`` parameter.
+    -   ``safe_join`` is removed, use ``werkzeug.utils.safe_join``
+        instead.
 
 
 Version 2.0.2

docs/api.rst

@@ -218,8 +218,6 @@ Useful Functions and Classes
 
 .. autofunction:: send_from_directory
 
-.. autofunction:: safe_join
-
 .. autofunction:: escape
 
 .. autoclass:: Markup

src/flask/__init__.py

@@ -23,7 +23,6 @@
 from .helpers import get_flashed_messages as get_flashed_messages
 from .helpers import get_template_attribute as get_template_attribute
 from .helpers import make_response as make_response
-from .helpers import safe_join as safe_join
 from .helpers import send_file as send_file
 from .helpers import send_from_directory as send_from_directory
 from .helpers import stream_with_context as stream_with_context

src/flask/helpers.py

@@ -11,7 +11,6 @@
 from threading import RLock
 
 import werkzeug.utils
-from werkzeug.exceptions import NotFound
 from werkzeug.routing import BuildError
 from werkzeug.urls import url_quote
 
@@ -627,29 +626,6 @@ def send_file(
     )
 
 
-def safe_join(directory: str, *pathnames: str) -> str:
-    """Safely join zero or more untrusted path components to a base
-    directory to avoid escaping the base directory.
-
-    :param directory: The trusted base directory.
-    :param pathnames: The untrusted path components relative to the
-        base directory.
-    :return: A safe path, otherwise ``None``.
-    """
-    warnings.warn(
-        "'flask.helpers.safe_join' is deprecated and will be removed in"
-        " Flask 2.1. Use 'werkzeug.utils.safe_join' instead.",
-        DeprecationWarning,
-        stacklevel=2,
-    )
-    path = werkzeug.utils.safe_join(directory, *pathnames)
-
-    if path is None:
-        raise NotFound()
-
-    return path
-
-
 def send_from_directory(
     directory: t.Union[os.PathLike, str],
     path: t.Union[os.PathLike, str],