From b6a18bb212580fc2e33851363bceddaf9256ae0e Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Wed, 17 Jun 2020 00:46:21 +0200
Subject: [PATCH 1/2] bpo-22433: do not consider "--foo='bar baz'" to be a
 positional argument

Ref: https://bugs.python.org/issue22433
---
 Lib/argparse.py           | 4 ++--
 Lib/test/test_argparse.py | 9 +++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 2fb1da59f942cf..d4b6fb53af8e11 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2223,8 +2223,8 @@ def _parse_optional(self, arg_string):
             if not self._has_negative_number_optionals:
                 return None
 
-        # if it contains a space, it was meant to be a positional
-        if ' ' in arg_string:
+        # if it contains a space (before any equal sign), it was meant to be a positional
+        if ' ' in arg_string.split("=", 1)[0]:
             return None
 
         # it was meant to be an optional but there is no such option
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 22cae626ccc297..60a18b00806892 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -2018,6 +2018,15 @@ def test_parse_known_args(self):
             self.parser.parse_known_args('0.5 -W 1 b -X Y -w 7 Z'.split()),
             (NS(foo=False, bar=0.5, w=7, x='b'), ['-W', '-X', 'Y', 'Z']),
         )
+        self.assertEqual(
+            self.parser.parse_known_args(['0.5', '--opt="with space"']),
+            (NS(foo=False, bar=0.5), ['--opt="with space"']),
+        )
+        self.assertRaisesRegexp(
+            ArgumentParserError,
+            "invalid choice: '--opt with space'",
+            self.parser.parse_known_args,
+            ['0.5', '--opt with space'])
 
     def test_dest(self):
         parser = ErrorRaisingArgumentParser()

From 6c2d2033f066ce9bdda72c018cad031f8dafb69c Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Mon, 6 Jul 2020 15:25:47 +0200
Subject: [PATCH 2/2] fixup! bpo-22433: do not consider "--foo='bar baz'" to be
 a positional argument

---
 Lib/argparse.py                                                | 3 ++-
 Lib/test/test_argparse.py                                      | 2 +-
 .../next/Library/2020-07-06-15-25-29.bpo-22433.JBnwdX.rst      | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2020-07-06-15-25-29.bpo-22433.JBnwdX.rst

diff --git a/Lib/argparse.py b/Lib/argparse.py
index d4b6fb53af8e11..acd3154e681e0e 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2223,7 +2223,8 @@ def _parse_optional(self, arg_string):
             if not self._has_negative_number_optionals:
                 return None
 
-        # if it contains a space (before any equal sign), it was meant to be a positional
+        # if it contains a space (before any equal sign), it was meant to be a
+        # positional
         if ' ' in arg_string.split("=", 1)[0]:
             return None
 
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 60a18b00806892..f378606cdecbd3 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -2022,7 +2022,7 @@ def test_parse_known_args(self):
             self.parser.parse_known_args(['0.5', '--opt="with space"']),
             (NS(foo=False, bar=0.5), ['--opt="with space"']),
         )
-        self.assertRaisesRegexp(
+        self.assertRaisesRegex(
             ArgumentParserError,
             "invalid choice: '--opt with space'",
             self.parser.parse_known_args,
diff --git a/Misc/NEWS.d/next/Library/2020-07-06-15-25-29.bpo-22433.JBnwdX.rst b/Misc/NEWS.d/next/Library/2020-07-06-15-25-29.bpo-22433.JBnwdX.rst
new file mode 100644
index 00000000000000..aa0adb5a732987
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-07-06-15-25-29.bpo-22433.JBnwdX.rst
@@ -0,0 +1,2 @@
+Fixed handling of "--foo='bar baz'" as non-positional argument with
+:mod:`argparse`.