Add deprecation for %e with no year

Author: StanFromIreland

Doc/library/datetime.rst

@@ -2531,13 +2531,13 @@ requires, and these work on all supported platforms.
 |           | truncated to an integer as a   |                        |       |
 |           | zero-padded decimal number.    |                        |       |
 +-----------+--------------------------------+------------------------+-------+
-|  ``%d``   | Day of the month as a          | 01, 02, ..., 31        | \(9)  |
-|           | zero-padded decimal number.    |                        |       |
+|  ``%d``   | Day of the month as a          | 01, 02, ..., 31        | \(9), |
+|           | zero-padded decimal number.    |                        | \(10  |
 +-----------+--------------------------------+------------------------+-------+
 |  ``%D``   | Equivalent to ``%m/%d/%y``.    | 11/10/2025             | \(9), |
 |           |                                |                        | \(0)  |
 +-----------+--------------------------------+------------------------+-------+
-|  ``%e``   | The day of the month as a      | ␣1, ␣2, ..., 31        |       |
+|  ``%e``   | The day of the month as a      | ␣1, ␣2, ..., 31        | \(10) |
 |           | space-padded decimal number.   |                        |       |
 +-----------+--------------------------------+------------------------+-------+
 |  ``%F``   | Equivalent to ``%Y-%m-%d``,    | 2025-10-11,            | \(0)  |

Lib/_strptime.py

@@ -466,7 +466,7 @@ def repl(m):
                 case 'Y' | 'y' | 'G':
                     nonlocal year_in_format
                     year_in_format = True
-                case 'd':
+                case 'd' | 'e':
                     nonlocal day_of_month_in_format
                     day_of_month_in_format = True
             return self[directive]
@@ -475,8 +475,8 @@ def repl(m):
             import warnings
             warnings.warn("""\
 Parsing dates involving a day of month without a year specified is ambiguous
-and fails to parse leap day. The default behavior will change in Python 3.15
-to either always raise an exception or to use a different default year (TBD).
+and fails to parse leap day. The default behavior will change in a future Python
+version to either always raise an exception or to use a different default year.
 To avoid trouble, add a specific year to the input & format.
 See https://github.com/python/cpython/issues/70647.""",
                           DeprecationWarning,

Lib/test/datetimetester.py

@@ -1208,9 +1208,12 @@ def test_strptime_leap_year(self):
         with self.assertRaises(ValueError):
             # The existing behavior that GH-70647 seeks to change.
             date.strptime('02-29', '%m-%d')
+        with self.assertRaises(ValueError):
+            date.strptime('02-29', '%m-%e')
         with self._assertNotWarns(DeprecationWarning):
             date.strptime('20-03-14', '%y-%m-%d')
             date.strptime('02-29,2024', '%m-%d,%Y')
+            date.strptime('02-29,2024', '%m-%e,%Y')
 
 class SubclassDate(date):
     sub_var = 1
@@ -3096,10 +3099,15 @@ def test_strptime_leap_year(self):
         with self.assertWarnsRegex(DeprecationWarning,
                                    r'.*day of month without a year.*'):
             self.theclass.strptime('03-14.159265', '%m-%d.%f')
+        with self.assertWarnsRegex(DeprecationWarning,
+                                   r'.*day of month without a year.*'):
+            self.theclass.strptime('03-14.159265', '%m-%e.%f')
         with self._assertNotWarns(DeprecationWarning):
             self.theclass.strptime('20-03-14.159265', '%y-%m-%d.%f')
         with self._assertNotWarns(DeprecationWarning):
             self.theclass.strptime('02-29,2024', '%m-%d,%Y')
+        with self._assertNotWarns(DeprecationWarning):
+            self.theclass.strptime('02-29,2024', '%m-%e,%Y')
 
     def test_strptime_z_empty(self):
         for directive in ('z', ':z'):

Lib/test/test_time.py

@@ -358,11 +358,11 @@ def test_strptime(self):
         # Should be able to go round-trip from strftime to strptime without
         # raising an exception.
         tt = time.gmtime(self.t)
-        for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'H', 'I',
+        for directive in ('a', 'A', 'b', 'B', 'c', 'd', 'e', 'H', 'I',
                           'j', 'm', 'M', 'p', 'S',
                           'U', 'w', 'W', 'x', 'X', 'y', 'Y', 'Z', '%'):
             format = '%' + directive
-            if directive == 'd':
+            if directive in ('d', 'e'):
                 format += ',%Y'  # Avoid GH-70647.
             strf_output = time.strftime(format, tt)
             try:
@@ -391,6 +391,9 @@ def test_strptime_leap_year(self):
         with self.assertWarnsRegex(DeprecationWarning,
                                    r'.*day of month without a year.*'):
             time.strptime('02-07 18:28', '%m-%d %H:%M')
+        with self.assertWarnsRegex(DeprecationWarning,
+                                   r'.*day of month without a year.*'):
+            time.strptime('02- 7 18:28', '%m-%e %H:%M')
 
     def test_asctime(self):
         time.asctime(time.gmtime(self.t))