From: Savannah Ostrowski <savannahostrowski@gmail.com>
Date: Mon, 23 Sep 2024 18:16:55 +0000 (-0700)
Subject: GH-124321: Fix argparse negative number parsing to capture -.5(GH-124322)
X-Git-Tag: v3.14.0a1~401
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=dc48312717142ec902197da504fad333f13c9937;p=thirdparty%2FPython%2Fcpython.git

GH-124321: Fix argparse negative number parsing to capture -.5(GH-124322)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
---

diff --git a/Lib/argparse.py b/Lib/argparse.py
index 7988c447d035..b77da29417b9 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1360,7 +1360,7 @@ class _ActionsContainer(object):
         self._defaults = {}
 
         # determines whether an "option" looks like a negative number
-        self._negative_number_matcher = _re.compile(r'^-\d[\d_]*(\.\d[\d_]*)?$')
+        self._negative_number_matcher = _re.compile(r'^-(?:\d+(?:_\d+)*(?:\.\d+(?:_\d+)*)?|\.\d+(?:_\d+)*)$')
 
         # whether or not there are any optionals that look like negative
         # numbers -- uses a list so it can be shared and edited
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 138ff19e86ac..37d07968b225 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -2111,6 +2111,8 @@ class TestNegativeNumber(ParserTestCase):
         ('--int -1_000_000 --float -1_000_000.0', NS(int=-1000000, float=-1000000.0)),
         ('--float -1_000.0', NS(int=None, float=-1000.0)),
         ('--float -1_000_000.0_0', NS(int=None, float=-1000000.0)),
+        ('--float -.5', NS(int=None, float=-0.5)),
+        ('--float -.5_000', NS(int=None, float=-0.5)),
     ]
 
 class TestInvalidAction(TestCase):