From 49e105f9488de18d3d92948232fcbd956cbe0c6e Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Sun, 29 Sep 2024 10:44:34 +0300
Subject: gh-104860: Fix allow_abbrev=False for single-dash long options
 (GH-124340)

---
 Lib/argparse.py                                         |  2 +-
 Lib/test/test_argparse.py                               | 17 +++++++++++++++++
 .../2024-09-23-17-33-47.gh-issue-104860.O86OSc.rst      |  2 ++
 3 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-09-23-17-33-47.gh-issue-104860.O86OSc.rst

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 690b2a9..4506a5e 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -2328,7 +2328,7 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                     action = self._option_string_actions[option_string]
                     tup = action, option_string, '', short_explicit_arg
                     result.append(tup)
-                elif option_string.startswith(option_prefix):
+                elif self.allow_abbrev and option_string.startswith(option_prefix):
                     action = self._option_string_actions[option_string]
                     tup = action, option_string, None, None
                     result.append(tup)
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index ef05a6f..26e32c3 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -914,6 +914,23 @@ class TestOptionalsDisallowLongAbbreviationPrefixChars(ParserTestCase):
     ]
 
 
+class TestOptionalsDisallowSingleDashLongAbbreviation(ParserTestCase):
+    """Do not allow abbreviations of long options at all"""
+
+    parser_signature = Sig(allow_abbrev=False)
+    argument_signatures = [
+        Sig('-foo'),
+        Sig('-foodle', action='store_true'),
+        Sig('-foonly'),
+    ]
+    failures = ['-foon 3', '-food', '-food -foo 2']
+    successes = [
+        ('', NS(foo=None, foodle=False, foonly=None)),
+        ('-foo 3', NS(foo='3', foodle=False, foonly=None)),
+        ('-foonly 7 -foodle -foo 2', NS(foo='2', foodle=True, foonly='7')),
+    ]
+
+
 class TestDisallowLongAbbreviationAllowsShortGrouping(ParserTestCase):
     """Do not allow abbreviations of long options at all"""
 
diff --git a/Misc/NEWS.d/next/Library/2024-09-23-17-33-47.gh-issue-104860.O86OSc.rst b/Misc/NEWS.d/next/Library/2024-09-23-17-33-47.gh-issue-104860.O86OSc.rst
new file mode 100644
index 0000000..707c4d6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-09-23-17-33-47.gh-issue-104860.O86OSc.rst
@@ -0,0 +1,2 @@
+Fix disallowing abbreviation of single-dash long options in :mod:`argparse`
+with ``allow_abbrev=False``.
-- 
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