From c83d0032185ac63619f338e066e348146af0bb79 Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 19:02:23 +0300
Subject: [PATCH 1/7] bpo-19094: Raise TypeError in urljoin(), urlparse(), and
 urlsplit() for inappropriate types

---
 Doc/library/urllib.parse.rst                  | 25 +++++++++++++++++
 Doc/whatsnew/3.15.rst                         |  6 ++++
 Lib/test/test_urlparse.py                     | 28 +++++++++++++++++++
 Lib/urllib/parse.py                           | 14 ++++++++--
 .../2021-06-11-20-00-16.bpo-19094.rMRoIL.rst  |  3 ++
 5 files changed, 73 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2021-06-11-20-00-16.bpo-19094.rMRoIL.rst

diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
index ef48addaba03e9..26400537206d00 100644
--- a/Doc/library/urllib.parse.rst
+++ b/Doc/library/urllib.parse.rst
@@ -220,6 +220,11 @@ or on combining URL components into a URL string.
    .. versionchanged:: 3.15
       Added the *missing_as_none* parameter.
 
+   .. versionchanged:: 3.15
+       Values for ``url`` and ``scheme`` other than strings or bytes raise
+      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
+      changed to :exc:`TypeError` in future versions of Python).
+
 .. _WHATWG spec: https://url.spec.whatwg.org/#concept-basic-url-parser
 
 
@@ -315,6 +320,11 @@ or on combining URL components into a URL string.
       query parameter separator. This has been changed to allow only a single
       separator key, with ``&`` as the default separator.
 
+   .. versionchanged:: 3.15
+      Values for ``qs`` and ``separator`` other than strings or bytes raise
+      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
+      changed to :exc:`TypeError` in future versions of Python).
+
 
 .. function:: urlunsplit(parts)
               urlunsplit(parts, *, keep_empty)
@@ -374,6 +384,11 @@ or on combining URL components into a URL string.
    .. versionchanged:: 3.15
       Added the *keep_empty* parameter.
 
+   .. versionchanged:: 3.15
+      Items in ``parts`` other than strings or bytes raise
+      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
+      changed to :exc:`TypeError` in future versions of Python).
+
 
 .. function:: urljoin(base, url, allow_fragments=True)
 
@@ -417,6 +432,11 @@ or on combining URL components into a URL string.
 
       Behavior updated to match the semantics defined in :rfc:`3986`.
 
+   .. versionchanged:: 3.15
+      Values for ``base`` and ``url`` other than strings or bytes raise
+      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
+      changed to :exc:`TypeError` in future versions of Python).
+
 
 .. function:: urldefrag(url, *, missing_as_none=False)
 
@@ -447,6 +467,11 @@ or on combining URL components into a URL string.
    .. versionchanged:: 3.15
       Added the *missing_as_none* parameter.
 
+   .. versionchanged:: 3.15
+      Values other than strings or bytes raise
+      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
+      changed to :exc:`TypeError` in future versions of Python).
+
 .. function:: unwrap(url)
 
    Extract the url from a wrapped URL (that is, a string formatted as
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index c4dac339be66af..384e92980e1143 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1761,6 +1761,12 @@ New deprecations
     :func:`issubclass`, but warnings were not previously emitted if it was
     merely imported or accessed from the :mod:`!typing` module.
 
+* :mod:`urllib`:
+
+  * Providing anything but a string or bytes object to :mod:`urllib.parse`
+    functions expecting strings or bytes now raises :exc:`DeprecationWarning`
+    if the value tests false, or :exc:`TypeError` if it tests true.
+    (Contributed by Jacob Walls in :issue:`19094`.)
 
 * ``__version__``
 
diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 8e4da0e0f09919..51ee12d0957d14 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -1255,7 +1255,14 @@ def test_mixed_types_rejected(self):
         with self.assertRaisesRegex(TypeError, "Cannot mix str"):
             urllib.parse.urljoin(b"http://python.org", "http://python.org")
 
+    def test_non_string_true_values_rejected(self):
+        # True values raise informative TypeErrors
+        msg = "Expected a string or bytes object: got <class "
+        with self.assertRaisesRegex(TypeError, msg):
+            urllib.parse.urlsplit(1, b'http')
+
     def _check_result_type(self, str_type, str_args):
+        num_args = len(str_type._fields)
         bytes_type = str_type._encoded_counterpart
         self.assertIs(bytes_type._decoded_counterpart, str_type)
         bytes_args = tuple_encode(str_args)
@@ -1987,6 +1994,27 @@ def test_to_bytes_deprecation(self):
         self.assertEqual(str(cm.warning),
                          'urllib.parse.to_bytes() is deprecated as of 3.8')
 
+    def test_falsey_deprecation(self):
+        pattern = (
+            "Providing false values other than strings or bytes to urllib.parse "
+            "is deprecated: got <class "
+        )
+        cases = [
+            (urllib.parse.urljoin, ['http://www.python.org', []]),
+            (urllib.parse.urljoin, [[], b'docs']),
+            (urllib.parse.urlparse, [b'www.python.org', None]),
+            (urllib.parse.urlparse, [{}, '']),
+            (urllib.parse.urlsplit, [0, b'http']),
+            (urllib.parse.urlsplit, [b'http://www.python.org', None]),
+            (urllib.parse.urldefrag, [{}]),
+            (urllib.parse.urlunparse, [[None, b'www.python.org', None, None, None, None]]),
+            (urllib.parse.urlunsplit, [['http', 0, '', '', '']]),
+        ]
+        for callable, args in cases:
+            with self.subTest(callable=callable):
+                with self.assertWarnsRegex(DeprecationWarning, pattern):
+                    callable(*args)
+
 
 def str_encode(s):
     if s is None:
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index d64f678d235b6f..ef539fa5d815e2 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -131,6 +131,14 @@ def _coerce_args(*args):
             else:
                 if isinstance(arg, str) != str_input:
                     raise TypeError("Cannot mix str and non-str arguments")
+                if not hasattr(arg, 'decode'):
+                    if arg:
+                        raise TypeError(f"Expected a string or bytes object: got {type(arg)}")
+                    else:
+                        warnings.warn(
+                            f"Providing false values other than strings or bytes "
+                            f"to urllib.parse is deprecated: got {type(arg)}",
+                            DeprecationWarning, stacklevel=3)
     if str_input is None:
         for arg in args:
             if arg is not None:
@@ -697,12 +705,12 @@ def _urlunsplit(scheme, netloc, url, query, fragment):
 def urljoin(base, url, allow_fragments=True):
     """Join a base URL and a possibly relative URL to form an absolute
     interpretation of the latter."""
+    base, url, _coerce_result = _coerce_args(base, url)
     if not base:
-        return url
+        return _coerce_result(url)
     if not url:
-        return base
+        return _coerce_result(base)
 
-    base, url, _coerce_result = _coerce_args(base, url)
     bscheme, bnetloc, bpath, bquery, bfragment = \
             _urlsplit(base, None, allow_fragments)
     scheme, netloc, path, query, fragment = \
diff --git a/Misc/NEWS.d/next/Library/2021-06-11-20-00-16.bpo-19094.rMRoIL.rst b/Misc/NEWS.d/next/Library/2021-06-11-20-00-16.bpo-19094.rMRoIL.rst
new file mode 100644
index 00000000000000..51c864b91a5fe0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-06-11-20-00-16.bpo-19094.rMRoIL.rst
@@ -0,0 +1,3 @@
+Providing anything but a string or bytes object to :mod:`urllib.parse`
+functions expecting strings or bytes now raises :exc:`DeprecationWarning`
+if the value tests false, or :exc:`TypeError` if it tests true.

From 3ec0a4bf34a73ffcd24b027f85bbc5339872d173 Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 19:11:49 +0300
Subject: [PATCH 2/7] fix missing elif

---
 Lib/urllib/parse.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index ef539fa5d815e2..639767ea561983 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -131,7 +131,7 @@ def _coerce_args(*args):
             else:
                 if isinstance(arg, str) != str_input:
                     raise TypeError("Cannot mix str and non-str arguments")
-                if not hasattr(arg, 'decode'):
+                elif not hasattr(arg, 'decode'):
                     if arg:
                         raise TypeError(f"Expected a string or bytes object: got {type(arg)}")
                     else:

From 2bf57f3803b4b9a3db80ce12ed4e253396672cbc Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 19:13:17 +0300
Subject: [PATCH 3/7] fix condition

---
 Lib/urllib/parse.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 639767ea561983..41e157960a5ba2 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -131,7 +131,7 @@ def _coerce_args(*args):
             else:
                 if isinstance(arg, str) != str_input:
                     raise TypeError("Cannot mix str and non-str arguments")
-                elif not hasattr(arg, 'decode'):
+                elif str_input is False and not hasattr(arg, 'decode'):
                     if arg:
                         raise TypeError(f"Expected a string or bytes object: got {type(arg)}")
                     else:

From bffbd321c4171345b40841cd06d9b687fca69968 Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 16:03:22 -0400
Subject: [PATCH 4/7] Allow NoneType

---
 Doc/library/urllib.parse.rst | 22 +++++++++++-----------
 Doc/whatsnew/3.15.rst        |  7 ++++---
 Lib/urllib/parse.py          | 16 ++++++++--------
 3 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
index 26400537206d00..24b2ed47d43485 100644
--- a/Doc/library/urllib.parse.rst
+++ b/Doc/library/urllib.parse.rst
@@ -221,9 +221,9 @@ or on combining URL components into a URL string.
       Added the *missing_as_none* parameter.
 
    .. versionchanged:: 3.15
-       Values for ``url`` and ``scheme`` other than strings or bytes raise
-      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
-      changed to :exc:`TypeError` in future versions of Python).
+      Values for ``url`` and ``scheme`` other than strings, bytes, or ``None``
+      raise :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to
+      be changed to :exc:`TypeError` in future versions of Python).
 
 .. _WHATWG spec: https://url.spec.whatwg.org/#concept-basic-url-parser
 
@@ -321,9 +321,9 @@ or on combining URL components into a URL string.
       separator key, with ``&`` as the default separator.
 
    .. versionchanged:: 3.15
-      Values for ``qs`` and ``separator`` other than strings or bytes raise
-      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
-      changed to :exc:`TypeError` in future versions of Python).
+      Values for ``qs`` and ``separator`` other than strings, bytes, or
+      ``None`` raise :exc:`TypeError` if true or :exc:`DeprecationWarning` if
+      false (to be changed to :exc:`TypeError` in future versions of Python).
 
 
 .. function:: urlunsplit(parts)
@@ -385,7 +385,7 @@ or on combining URL components into a URL string.
       Added the *keep_empty* parameter.
 
    .. versionchanged:: 3.15
-      Items in ``parts`` other than strings or bytes raise
+      Items in ``parts`` other than strings, bytes, or ``None`` raise
       :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
       changed to :exc:`TypeError` in future versions of Python).
 
@@ -433,9 +433,9 @@ or on combining URL components into a URL string.
       Behavior updated to match the semantics defined in :rfc:`3986`.
 
    .. versionchanged:: 3.15
-      Values for ``base`` and ``url`` other than strings or bytes raise
-      :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
-      changed to :exc:`TypeError` in future versions of Python).
+      Values for ``base`` and ``url`` other than strings, bytes, or ``None``
+      raise :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to
+      be changed to :exc:`TypeError` in future versions of Python).
 
 
 .. function:: urldefrag(url, *, missing_as_none=False)
@@ -468,7 +468,7 @@ or on combining URL components into a URL string.
       Added the *missing_as_none* parameter.
 
    .. versionchanged:: 3.15
-      Values other than strings or bytes raise
+      Values other than other than strings, bytes, or ``None`` raise
       :exc:`TypeError` if true or :exc:`DeprecationWarning` if false (to be
       changed to :exc:`TypeError` in future versions of Python).
 
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 384e92980e1143..f67c6220a5d6b6 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1763,9 +1763,10 @@ New deprecations
 
 * :mod:`urllib`:
 
-  * Providing anything but a string or bytes object to :mod:`urllib.parse`
-    functions expecting strings or bytes now raises :exc:`DeprecationWarning`
-    if the value tests false, or :exc:`TypeError` if it tests true.
+  * Providing anything but a string, bytes object, or ``None`` to
+    :mod:`urllib.parse` functions expecting strings or bytes now raises
+    :exc:`DeprecationWarning` if the value tests false, or :exc:`TypeError` if
+    it tests true.
     (Contributed by Jacob Walls in :issue:`19094`.)
 
 * ``__version__``
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 41e157960a5ba2..205b4b5e591de4 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -124,6 +124,7 @@ def _coerce_args(*args):
     #   - noop for str inputs
     #   - encoding function otherwise
     str_input = None
+    empty_values = {"", b"", None}
     for arg in args:
         if arg:
             if str_input is None:
@@ -131,14 +132,13 @@ def _coerce_args(*args):
             else:
                 if isinstance(arg, str) != str_input:
                     raise TypeError("Cannot mix str and non-str arguments")
-                elif str_input is False and not hasattr(arg, 'decode'):
-                    if arg:
-                        raise TypeError(f"Expected a string or bytes object: got {type(arg)}")
-                    else:
-                        warnings.warn(
-                            f"Providing false values other than strings or bytes "
-                            f"to urllib.parse is deprecated: got {type(arg)}",
-                            DeprecationWarning, stacklevel=3)
+            if str_input is False and arg is not None and not hasattr(arg, "decode"):
+                raise TypeError(f"Expected a string, bytes, or None: got {type(arg)}")
+        elif arg not in empty_values:
+            warnings.warn(
+                f"Providing false values other than empty strings, bytes, or"
+                f"None to urllib.parse is deprecated: got {type(arg)}",
+                DeprecationWarning, stacklevel=3)
     if str_input is None:
         for arg in args:
             if arg is not None:

From 01809a91425de2f64b86eda012703d2afd94823f Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 16:06:16 -0400
Subject: [PATCH 5/7] Relax assertion

---
 Lib/test/test_urlparse.py | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index 51ee12d0957d14..d55ea6b8b3bff9 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -1995,10 +1995,6 @@ def test_to_bytes_deprecation(self):
                          'urllib.parse.to_bytes() is deprecated as of 3.8')
 
     def test_falsey_deprecation(self):
-        pattern = (
-            "Providing false values other than strings or bytes to urllib.parse "
-            "is deprecated: got <class "
-        )
         cases = [
             (urllib.parse.urljoin, ['http://www.python.org', []]),
             (urllib.parse.urljoin, [[], b'docs']),
@@ -2011,8 +2007,8 @@ def test_falsey_deprecation(self):
             (urllib.parse.urlunsplit, [['http', 0, '', '', '']]),
         ]
         for callable, args in cases:
-            with self.subTest(callable=callable):
-                with self.assertWarnsRegex(DeprecationWarning, pattern):
+            with self.subTest(callable=callable.__name__, args=args):
+                with self.assertWarnsRegex(DeprecationWarning, "false values"):
                     callable(*args)
 
 

From 6fc29013bccd4a9e69e31a49de6cf9f858febf0d Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Mon, 20 Apr 2026 16:19:16 -0400
Subject: [PATCH 6/7] fixups

---
 Lib/test/test_urlparse.py | 8 ++++----
 Lib/urllib/parse.py       | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
index d55ea6b8b3bff9..ff5cf70ee30470 100644
--- a/Lib/test/test_urlparse.py
+++ b/Lib/test/test_urlparse.py
@@ -1257,7 +1257,7 @@ def test_mixed_types_rejected(self):
 
     def test_non_string_true_values_rejected(self):
         # True values raise informative TypeErrors
-        msg = "Expected a string or bytes object: got <class "
+        msg = "Expected a string, bytes, or None: got <class "
         with self.assertRaisesRegex(TypeError, msg):
             urllib.parse.urlsplit(1, b'http')
 
@@ -1998,12 +1998,12 @@ def test_falsey_deprecation(self):
         cases = [
             (urllib.parse.urljoin, ['http://www.python.org', []]),
             (urllib.parse.urljoin, [[], b'docs']),
-            (urllib.parse.urlparse, [b'www.python.org', None]),
+            (urllib.parse.urlparse, [b'www.python.org', {}]),
             (urllib.parse.urlparse, [{}, '']),
             (urllib.parse.urlsplit, [0, b'http']),
-            (urllib.parse.urlsplit, [b'http://www.python.org', None]),
+            (urllib.parse.urlsplit, [b'http://www.python.org', 0]),
             (urllib.parse.urldefrag, [{}]),
-            (urllib.parse.urlunparse, [[None, b'www.python.org', None, None, None, None]]),
+            (urllib.parse.urlunparse, [[None, b'www.python.org', (), (), (), ()]]),
             (urllib.parse.urlunsplit, [['http', 0, '', '', '']]),
         ]
         for callable, args in cases:
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 205b4b5e591de4..e17e8eabb7dbc9 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -134,7 +134,7 @@ def _coerce_args(*args):
                     raise TypeError("Cannot mix str and non-str arguments")
             if str_input is False and arg is not None and not hasattr(arg, "decode"):
                 raise TypeError(f"Expected a string, bytes, or None: got {type(arg)}")
-        elif arg not in empty_values:
+        elif arg is not None and arg != "" and arg != b"":
             warnings.warn(
                 f"Providing false values other than empty strings, bytes, or"
                 f"None to urllib.parse is deprecated: got {type(arg)}",

From 4f2c6868f15105e4d487b2de9dc614333cfc255c Mon Sep 17 00:00:00 2001
From: Jacob Walls <jacobtylerwalls@gmail.com>
Date: Tue, 21 Apr 2026 06:52:43 -0400
Subject: [PATCH 7/7] fixups

---
 Lib/urllib/parse.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index e17e8eabb7dbc9..b1d442e4778aca 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -132,9 +132,9 @@ def _coerce_args(*args):
             else:
                 if isinstance(arg, str) != str_input:
                     raise TypeError("Cannot mix str and non-str arguments")
-            if str_input is False and arg is not None and not hasattr(arg, "decode"):
+            if arg is not None and str_input is False and not hasattr(arg, "decode"):
                 raise TypeError(f"Expected a string, bytes, or None: got {type(arg)}")
-        elif arg is not None and arg != "" and arg != b"":
+        elif arg is not None and not isinstance(arg, str) and not hasattr(arg, "decode"):
             warnings.warn(
                 f"Providing false values other than empty strings, bytes, or"
                 f"None to urllib.parse is deprecated: got {type(arg)}",