merge revision(s) 3f07bc76ff6a11232d9f18e5eaa31835c195e8f0, 34098b669c0cbc024cd08e686891f1dfe0a10aaf: [Backport #21144]

	[Bug #21144] Win32: Use Windows time zone ID if TZ is not set

	If the TZ environment variable is not set, the time zone names
	retrieved from the system are localized for UI display and may vary
	across editions and language packs for the same time zone.
	Use the time zone IDs that are invariant across environments instead.

	[Bug #21144] Win32: Convert the time zone name to the current locale

	The Windows time zone IDs provided by Microsoft as of 24H1 are ASCII
	only all, but the API itself is not impossible to set non-ASCII key
	name.  Prefer the current locale encoding for now until we move to
	UTF-8 including environment variables and command line arguments.

4 files changed, 67 insertions, 11 deletions

diff --git a/hash.c b/hash.c
index 4f6196fd4f..d2dce30624 100644
--- a/hash.c
+++ b/hash.c
@@ -4995,7 +4995,7 @@ env_name(volatile VALUE *s)
 static VALUE env_aset(VALUE nm, VALUE val);
 
 static void
-reset_by_modified_env(const char *nam)
+reset_by_modified_env(const char *nam, const char *val)
 {
     /*
      * ENV['TZ'] = nil has a special meaning.
@@ -5004,7 +5004,7 @@ reset_by_modified_env(const char *nam)
      * This hack might works only on Linux glibc.
      */
     if (ENVMATCH(nam, TZ_ENV)) {
-        ruby_reset_timezone();
+        ruby_reset_timezone(val);
     }
 }
 
@@ -5012,7 +5012,7 @@ static VALUE
 env_delete(VALUE name)
 {
     const char *nam = env_name(name);
-    reset_by_modified_env(nam);
+    reset_by_modified_env(nam, NULL);
     VALUE val = getenv_with_lock(nam);
 
     if (!NIL_P(val)) {
@@ -5472,7 +5472,7 @@ env_aset(VALUE nm, VALUE val)
     get_env_ptr(value, val);
 
     ruby_setenv(name, value);
-    reset_by_modified_env(name);
+    reset_by_modified_env(name, value);
     return val;
 }
 
diff --git a/internal/time.h b/internal/time.h
index a3bf0587ec..e21b3574f6 100644
--- a/internal/time.h
+++ b/internal/time.h
@@ -28,7 +28,10 @@ struct timeval rb_time_timeval(VALUE);
 RUBY_SYMBOL_EXPORT_BEGIN
 /* time.c (export) */
 void ruby_reset_leap_second_info(void);
-void ruby_reset_timezone(void);
+#ifdef RBIMPL_ATTR_DEPRECATED_INTERNAL_ONLY
+RBIMPL_ATTR_DEPRECATED_INTERNAL_ONLY()
+#endif
+void ruby_reset_timezone(const char *);
 RUBY_SYMBOL_EXPORT_END
 
 #endif /* INTERNAL_TIME_H */
diff --git a/time.c b/time.c
index 04f6f2afc5..e8815b5e3d 100644
--- a/time.c
+++ b/time.c
@@ -44,6 +44,10 @@
 #include "ruby/encoding.h"
 #include "timev.h"
 
+#if defined(_WIN32)
+# include "timezoneapi.h" /* DYNAMIC_TIME_ZONE_INFORMATION */
+#endif
+
 #include "builtin.h"
 
 static ID id_submicro, id_nano_num, id_nano_den, id_offset, id_zone;
@@ -701,10 +705,51 @@ static VALUE tm_from_time(VALUE klass, VALUE time);
 
 bool ruby_tz_uptodate_p;
 
+#ifdef _WIN32
+enum {tzkey_max = numberof(((DYNAMIC_TIME_ZONE_INFORMATION *)NULL)->TimeZoneKeyName)};
+static struct {
+    char use_tzkey;
+    char name[tzkey_max * 4 + 1];
+} w32_tz;
+
+static char *
+get_tzname(int dst)
+{
+    if (w32_tz.use_tzkey) {
+        if (w32_tz.name[0]) {
+            return w32_tz.name;
+        }
+        else {
+            /*
+             * Use GetDynamicTimeZoneInformation::TimeZoneKeyName, Windows
+             * time zone ID, which is not localized because it is the key
+             * for "Dynamic DST" keys under the "Time Zones" registry.
+             * Available since Windows Vista and Windows Server 2008.
+             */
+            DYNAMIC_TIME_ZONE_INFORMATION tzi;
+            WCHAR *const wtzkey = tzi.TimeZoneKeyName;
+            DWORD tzret = GetDynamicTimeZoneInformation(&tzi);
+            if (tzret != TIME_ZONE_ID_INVALID && *wtzkey) {
+                int wlen = (int)wcsnlen(wtzkey, tzkey_max);
+                int clen = WideCharToMultiByte(CP_UTF8, 0, wtzkey, wlen,
+                                               w32_tz.name, sizeof(w32_tz.name) - 1,
+                                               NULL, NULL);
+                w32_tz.name[clen] = '\0';
+                return w32_tz.name;
+            }
+        }
+    }
+    return _tzname[_daylight && dst];
+}
+#endif
+
 void
-ruby_reset_timezone(void)
+ruby_reset_timezone(const char *val)
 {
     ruby_tz_uptodate_p = false;
+#ifdef _WIN32
+    w32_tz.use_tzkey = !val || !*val;
+#endif
     ruby_reset_leap_second_info();
 }
 
@@ -950,7 +995,13 @@ zone_str(const char *zone)
         str = rb_usascii_str_new(zone, len);
     }
     else {
+#ifdef _WIN32
+        str = rb_utf8_str_new(zone, len);
+        /* until we move to UTF-8 on Windows completely */
+        str = rb_str_export_locale(str);
+#else
         str = rb_enc_str_new(zone, len, rb_locale_encoding());
+#endif
     }
     return rb_fstring(str);
 }
@@ -1652,11 +1703,9 @@ localtime_with_gmtoff_zone(const time_t *t, struct tm *result, long *gmtoff, VAL
         if (zone) {
 #if defined(HAVE_TM_ZONE)
             *zone = zone_str(tm.tm_zone);
+#elif defined(_WIN32)
+            *zone = zone_str(get_tzname(tm.tm_isdst));
 #elif defined(HAVE_TZNAME) && defined(HAVE_DAYLIGHT)
-# if defined(RUBY_MSVCRT_VERSION) && RUBY_MSVCRT_VERSION >= 140
-#  define tzname _tzname
-#  define daylight _daylight
-# endif
             /* this needs tzset or localtime, instead of localtime_r */
             *zone = zone_str(tzname[daylight && tm.tm_isdst]);
 #else
@@ -5807,6 +5856,10 @@ rb_time_zone_abbreviation(VALUE zone, VALUE time)
 void
 Init_Time(void)
 {
+#ifdef _WIN32
+    ruby_reset_timezone(getenv("TZ"));
+#endif
+
     id_submicro = rb_intern_const("submicro");
     id_nano_num = rb_intern_const("nano_num");
     id_nano_den = rb_intern_const("nano_den");
diff --git a/version.h b/version.h
index fb18d49e35..c73d818e14 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 7
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 254
+#define RUBY_PATCHLEVEL 255
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"