From 7677be5ee6ffdc7b4b366ea29a86da50873cd731 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Sun, 29 Sep 2024 10:32:51 +0200
Subject: [PATCH] [3.12] gh-61181: Fix support of choices with string value in
 argparse (GH-124578) (GH-124756)

Substrings of the specified string no longer considered valid values.
(cherry picked from commit f1a2417b9e2993e584610851ac004c8b0599b323)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
---
 Doc/library/argparse.rst                           |  2 +-
 Lib/argparse.py                                    | 14 +++++++++-----
 Lib/test/test_argparse.py                          | 10 +++++-----
 .../2024-09-26-09-18-09.gh-issue-61181.dwjmch.rst  |  2 ++
 4 files changed, 17 insertions(+), 11 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-09-26-09-18-09.gh-issue-61181.dwjmch.rst

diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 8ed44fc809f7b4..632185b3f183f5 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -1774,7 +1774,7 @@ Sub-commands
      >>>
      >>> # create the parser for the "b" command
      >>> parser_b = subparsers.add_parser('b', help='b help')
-     >>> parser_b.add_argument('--baz', choices='XYZ', help='baz help')
+     >>> parser_b.add_argument('--baz', choices=('X', 'Y', 'Z'), help='baz help')
      >>>
      >>> # parse some argument lists
      >>> parser.parse_args(['a', '12'])
diff --git a/Lib/argparse.py b/Lib/argparse.py
index 8e9289b9d9977d..b0ab66ae223a2f 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2589,11 +2589,15 @@ def _get_value(self, action, arg_string):
 
     def _check_value(self, action, value):
         # converted value must be one of the choices (if specified)
-        if action.choices is not None and value not in action.choices:
-            args = {'value': value,
-                    'choices': ', '.join(map(repr, action.choices))}
-            msg = _('invalid choice: %(value)r (choose from %(choices)s)')
-            raise ArgumentError(action, msg % args)
+        choices = action.choices
+        if choices is not None:
+            if isinstance(choices, str):
+                choices = iter(choices)
+            if value not in choices:
+                args = {'value': value,
+                        'choices': ', '.join(map(repr, action.choices))}
+                msg = _('invalid choice: %(value)r (choose from %(choices)s)')
+                raise ArgumentError(action, msg % args)
 
     # =======================
     # Help-formatting methods
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index c66e803abf4d30..e65c65a0816a2d 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -686,7 +686,7 @@ class TestOptionalsChoices(ParserTestCase):
     argument_signatures = [
         Sig('-f', choices='abc'),
         Sig('-g', type=int, choices=range(5))]
-    failures = ['a', '-f d', '-fad', '-ga', '-g 6']
+    failures = ['a', '-f d', '-f ab', '-fad', '-ga', '-g 6']
     successes = [
         ('', NS(f=None, g=None)),
         ('-f a', NS(f='a', g=None)),
@@ -2227,14 +2227,14 @@ def _get_parser(self, subparser_help=False, prefix_chars=None,
             parser1_kwargs['aliases'] = ['1alias1', '1alias2']
         parser1 = subparsers.add_parser('1', **parser1_kwargs)
         parser1.add_argument('-w', type=int, help='w help')
-        parser1.add_argument('x', choices='abc', help='x help')
+        parser1.add_argument('x', choices=['a', 'b', 'c'], help='x help')
 
         # add second sub-parser
         parser2_kwargs = dict(description='2 description')
         if subparser_help:
             parser2_kwargs['help'] = '2 help'
         parser2 = subparsers.add_parser('2', **parser2_kwargs)
-        parser2.add_argument('-y', choices='123', help='y help')
+        parser2.add_argument('-y', choices=['1', '2', '3'], help='y help')
         parser2.add_argument('z', type=complex, nargs='*', help='z help')
 
         # add third sub-parser
@@ -4397,7 +4397,7 @@ class TestHelpVariableExpansion(HelpTestCase):
             help='x %(prog)s %(default)s %(type)s %%'),
         Sig('-y', action='store_const', default=42, const='XXX',
             help='y %(prog)s %(default)s %(const)s'),
-        Sig('--foo', choices='abc',
+        Sig('--foo', choices=['a', 'b', 'c'],
             help='foo %(prog)s %(default)s %(choices)s'),
         Sig('--bar', default='baz', choices=[1, 2], metavar='BBB',
             help='bar %(prog)s %(default)s %(dest)s'),
@@ -5057,7 +5057,7 @@ def test_no_argument_actions(self):
         for action in ['store_const', 'store_true', 'store_false',
                        'append_const', 'count']:
             for attrs in [dict(type=int), dict(nargs='+'),
-                          dict(choices='ab')]:
+                          dict(choices=['a', 'b'])]:
                 self.assertTypeError('-x', action=action, **attrs)
 
     def test_no_argument_no_const_actions(self):
diff --git a/Misc/NEWS.d/next/Library/2024-09-26-09-18-09.gh-issue-61181.dwjmch.rst b/Misc/NEWS.d/next/Library/2024-09-26-09-18-09.gh-issue-61181.dwjmch.rst
new file mode 100644
index 00000000000000..801a5fdd4abd4f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-09-26-09-18-09.gh-issue-61181.dwjmch.rst
@@ -0,0 +1,2 @@
+Fix support of :ref:`choices` with string value in :mod:`argparse`. Substrings
+of the specified string no longer considered valid values.