Issue #6478: _strptime's regexp cache now is reset after changing timezone

with time.tzset().

1 files changed, 14 insertions, 8 deletions

diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index fe5b046..8da4fcd 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -77,6 +77,8 @@ class LocaleTime(object):
         self.__calc_date_time()
         if _getlang() != self.lang:
             raise ValueError("locale changed during initialization")
+        if time.tzname != self.tzname or time.daylight != self.daylight:
+            raise ValueError("timezone changed during initialization")
 
     def __pad(self, seq, front):
         # Add '' to seq to either the front (is True), else the back.
@@ -161,15 +163,17 @@ class LocaleTime(object):
 
     def __calc_timezone(self):
         # Set self.timezone by using time.tzname.
-        # Do not worry about possibility of time.tzname[0] == timetzname[1]
-        # and time.daylight; handle that in strptime .
+        # Do not worry about possibility of time.tzname[0] == time.tzname[1]
+        # and time.daylight; handle that in strptime.
         try:
             time.tzset()
         except AttributeError:
             pass
-        no_saving = frozenset({"utc", "gmt", time.tzname[0].lower()})
-        if time.daylight:
-            has_saving = frozenset({time.tzname[1].lower()})
+        self.tzname = time.tzname
+        self.daylight = time.daylight
+        no_saving = frozenset({"utc", "gmt", self.tzname[0].lower()})
+        if self.daylight:
+            has_saving = frozenset({self.tzname[1].lower()})
         else:
             has_saving = frozenset()
         self.timezone = (no_saving, has_saving)
@@ -326,13 +330,15 @@ def _strptime(data_string, format="%a %b %d %H:%M:%S %Y"):
 
     global _TimeRE_cache, _regex_cache
     with _cache_lock:
-
-        if _getlang() != _TimeRE_cache.locale_time.lang:
+        locale_time = _TimeRE_cache.locale_time
+        if (_getlang() != locale_time.lang or
+            time.tzname != locale_time.tzname or
+            time.daylight != locale_time.daylight):
             _TimeRE_cache = TimeRE()
             _regex_cache.clear()
+            locale_time = _TimeRE_cache.locale_time
         if len(_regex_cache) > _CACHE_MAX_SIZE:
             _regex_cache.clear()
-        locale_time = _TimeRE_cache.locale_time
         format_regex = _regex_cache.get(format)
         if not format_regex:
             try: