Issue #14157: Fix time.strptime failing without a year on February 29th.

Patch by Hynek Schlawack.

Lib/_strptime.py

@@ -326,7 +326,8 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
     if len(data_string) != found.end():
         raise ValueError("unconverted data remains: %s" %
                           data_string[found.end():])
-    year = 1900
+
+    year = None
     month = day = 1
     hour = minute = second = fraction = 0
     tz = -1
@@ -425,6 +426,10 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
                     else:
                         tz = value
                         break
+    if year is None and month == 2 and day == 29:
+        year = 1904  # 1904 is first leap year of 20th century
+    elif year is None:
+        year = 1900
     # If we know the week of the year and what day of that week, we can figure
     # out the Julian day of the year.
     if julian == -1 and week_of_year != -1 and weekday != -1:

Lib/test/test_strptime.py

@@ -378,6 +378,9 @@ class StrptimeTests(unittest.TestCase):
         need_escaping = ".^$*+?{}\[]|)("
         self.assertTrue(_strptime._strptime_time(need_escaping, need_escaping))
 
+    def test_feb29_on_leap_year_without_year(self):
+        time.strptime("Feb 29", "%b %d")
+
 class Strptime12AMPMTests(unittest.TestCase):
     """Test a _strptime regression in '%I %p' at 12 noon (12 PM)"""
 

Misc/NEWS

@@ -60,6 +60,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #14157: Fix time.strptime failing without a year on February 29th.
+  Patch by Hynek Schlawack.
+
 - Issue #14768: os.path.expanduser('~/a') doesn't works correctly when HOME is '/'.
 
 - Issue #13183: Fix pdb skipping frames after hitting a breakpoint and running