From 542e984d82fa25098eb15398d716d907acc52b93 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sun, 1 Jan 2023 16:39:00 +0900
Subject: [PATCH] [Bug #19292] Re-initialize tm when wday or yday is not set

---
 test/ruby/test_time.rb |  3 ++-
 time.c                 | 31 ++++++++++++++++++++++---------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/test/ruby/test_time.rb b/test/ruby/test_time.rb
index 0977fea55f..8274dbbc83 100644
--- a/test/ruby/test_time.rb
+++ b/test/ruby/test_time.rb
@@ -54,7 +54,8 @@ class TestTime < Test::Unit::TestCase
     assert_raise_with_message(ArgumentError, msg) { Time.new(2021, 1, "+09:99") }
     assert_raise_with_message(ArgumentError, msg) { Time.new(2021, "+09:99") }
 
-    assert_equal([0, 0, 0, 2, 1, 2000], Time.new(2000, 1, 1, 24, 0, 0, "-00:00").to_a[0, 6])
+    assert_equal([0, 0, 0, 1, 1, 2000, 6, 1, false, "UTC"], Time.new(2000, 1, 1, 0, 0, 0, "-00:00").to_a)
+    assert_equal([0, 0, 0, 2, 1, 2000, 0, 2, false, "UTC"], Time.new(2000, 1, 1, 24, 0, 0, "-00:00").to_a)
   end
 
   def test_new_from_string
diff --git a/time.c b/time.c
index ee2d889a6a..02e88c140e 100644
--- a/time.c
+++ b/time.c
@@ -1790,6 +1790,7 @@ PACKED_STRUCT_UNALIGNED(struct time_object {
      (tobj1)->vtm.utc_offset = (tobj2)->vtm.utc_offset, \
      (tobj1)->vtm.zone = (tobj2)->vtm.zone)
 
+static int zone_localtime(VALUE zone, VALUE time);
 static VALUE time_get_tm(VALUE, struct time_object *);
 #define MAKE_TM(time, tobj) \
   do { \
@@ -1801,11 +1802,21 @@ static VALUE time_get_tm(VALUE, struct time_object *);
     do { \
         MAKE_TM(time, tobj); \
         if (!(cond)) { \
-            VALUE zone = (tobj)->vtm.zone; \
-            if (!NIL_P(zone)) zone_localtime(zone, (time)); \
+            force_make_tm(time, tobj); \
         } \
     } while (0)
 
+static inline void
+force_make_tm(VALUE time, struct time_object *tobj)
+{
+    VALUE zone = tobj->vtm.zone;
+    if (!NIL_P(zone) && zone != str_empty && zone != str_utc) {
+        if (zone_localtime(zone, time)) return;
+    }
+    tobj->tm_got = 0;
+    time_get_tm(time, tobj);
+}
+
 static void
 time_mark(void *ptr)
 {
@@ -2070,19 +2081,20 @@ vtm_add_day(struct vtm *vtm, int day)
                 vtm->mday = 31;
                 vtm->mon = 12; /* December */
                 vtm->year = subv(vtm->year, INT2FIX(1));
-                vtm->yday = leap_year_v_p(vtm->year) ? 366 : 365;
+                if (vtm->yday != 0)
+                    vtm->yday = leap_year_v_p(vtm->year) ? 366 : 365;
             }
             else if (vtm->mday == 1) {
                 const int8_t *days_in_month = days_in_month_in_v(vtm->year);
                 vtm->mon--;
                 vtm->mday = days_in_month[vtm->mon-1];
-                vtm->yday--;
+                if (vtm->yday != 0) vtm->yday--;
             }
             else {
                 vtm->mday--;
-                vtm->yday--;
+                if (vtm->yday != 0) vtm->yday--;
             }
-            vtm->wday = (vtm->wday + 6) % 7;
+            if (vtm->wday != VTM_WDAY_INITVAL) vtm->wday = (vtm->wday + 6) % 7;
         }
         else {
             int leap = leap_year_v_p(vtm->year);
@@ -2095,13 +2107,13 @@ vtm_add_day(struct vtm *vtm, int day)
             else if (vtm->mday == days_in_month_of(leap)[vtm->mon-1]) {
                 vtm->mon++;
                 vtm->mday = 1;
-                vtm->yday++;
+                if (vtm->yday != 0) vtm->yday++;
             }
             else {
                 vtm->mday++;
-                vtm->yday++;
+                if (vtm->yday != 0) vtm->yday++;
             }
-            vtm->wday = (vtm->wday + 1) % 7;
+            if (vtm->wday != VTM_WDAY_INITVAL) vtm->wday = (vtm->wday + 1) % 7;
         }
     }
 }
@@ -2449,6 +2461,7 @@ time_init_vtm(VALUE time, struct vtm vtm, VALUE zone)
 
     if (utc == UTC_ZONE) {
         tobj->timew = timegmw(&vtm);
+        vtm.isdst = 0; /* No DST in UTC */
         vtm_day_wraparound(&vtm);
         tobj->vtm = vtm;
         tobj->tm_got = 1;