From 75fde5d061dbf6f82cc10176de097a4ccc3e763c Mon Sep 17 00:00:00 2001
From: Sergey B Kirpichev <skirpichev@gmail.com>
Date: Tue, 15 Apr 2025 14:38:30 +0300
Subject: [PATCH] gh-130662: accept leading zeros in precision/width for
 Decimal's formatting

---
 Lib/_pydecimal.py        | 4 ++--
 Lib/test/test_decimal.py | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Lib/_pydecimal.py b/Lib/_pydecimal.py
index 38dc7b70e0f6f0..6534f644cf567a 100644
--- a/Lib/_pydecimal.py
+++ b/Lib/_pydecimal.py
@@ -6097,9 +6097,9 @@ def _convert_for_comparison(self, other, equality_op=False):
 (?P<no_neg_0>z)?
 (?P<alt>\#)?
 (?P<zeropad>0)?
-(?P<minimumwidth>(?!0)\d+)?
+(?P<minimumwidth>\d+)?
 (?P<thousands_sep>[,_])?
-(?:\.(?P<precision>0|(?!0)\d+))?
+(?:\.(?P<precision>\d+))?
 (?P<type>[eEfFgGn%])?
 \Z
 """, re.VERBOSE|re.DOTALL)
diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index fb14b80f7a8a2b..c90c10c0bc8942 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -982,6 +982,7 @@ def test_formatting(self):
             ('.0f', '0e-2', '0'),
             ('.0f', '3.14159265', '3'),
             ('.1f', '3.14159265', '3.1'),
+            ('.01f', '3.14159265', '3.1'), # leading zero in precision
             ('.4f', '3.14159265', '3.1416'),
             ('.6f', '3.14159265', '3.141593'),
             ('.7f', '3.14159265', '3.1415926'), # round-half-even!
@@ -1067,6 +1068,7 @@ def test_formatting(self):
             ('8,', '123456', ' 123,456'),
             ('08,', '123456', '0,123,456'), # special case: extra 0 needed
             ('+08,', '123456', '+123,456'), # but not if there's a sign
+            ('008,', '123456', '0,123,456'), # leading zero in width
             (' 08,', '123456', ' 123,456'),
             ('08,', '-123456', '-123,456'),
             ('+09,', '123456', '+0,123,456'),