gh-61449: handle 0-padding option for Decimals like for floats

Author: skirpichev

Lib/_pydecimal.py

@@ -6187,13 +6187,15 @@ def _parse_format_specifier(format_spec, _localeconv=None):
     fill = format_dict['fill']
     align = format_dict['align']
     format_dict['zeropad'] = (format_dict['zeropad'] is not None)
+
+    # Support zeropad handling like built-in types (see gh-61449).
     if format_dict['zeropad']:
-        if fill is not None:
-            raise ValueError("Fill character conflicts with '0'"
-                             " in format specifier: " + format_spec)
-        if align is not None:
-            raise ValueError("Alignment conflicts with '0' in "
-                             "format specifier: " + format_spec)
+        if fill is not None and align is not None:
+            format_dict['zeropad'] = False
+        elif align is not None:
+            format_dict['zeropad'] = False
+            fill = "0"
+
     format_dict['fill'] = fill or ' '
     # PEP 3101 originally specified that the default alignment should
     # be left;  it was later agreed that right-aligned makes more sense

Lib/test/test_decimal.py

@@ -1164,6 +1164,10 @@ def test_formatting(self):
             ('<^+15.20%', 'inf', '<<+Infinity%<<<'),
             ('\x07>,%', 'sNaN1234567', 'sNaN1234567%'),
             ('=10.10%', 'NaN123', '   NaN123%'),
+
+            # issue 61449
+            ('<06', '1.2', '1.2000'),
+            ('x>06', '1.2', 'xxx1.2'),
             ]
         for fmt, d, result in test_values:
             self.assertEqual(format(Decimal(d), fmt), result)

Misc/NEWS.d/next/Library/2026-03-10-19-48-18.gh-issue-61449.0DofsC.rst

@@ -0,0 +1,2 @@
+Align support of zero-padding option for :class:`~decimal.Decimal`
+formatting with builtin numeric types.  Patch by Sergey B Kirpichev.