Re-apply r63848 (Optimize Time.utc)

* Both timegmw and gmtimew ignores leap second if the timezone doesn't
  have leap seconds on the first call of init_leap_second_info()
* Add Bug::Time.reset_leap_second_info for testing

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63857 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 53 insertions, 2 deletions

diff --git a/internal.h b/internal.h
index b555bbab06..fb7679eace 100644
--- a/internal.h
+++ b/internal.h
@@ -2056,6 +2056,9 @@ VALUE rb_str_upto_endless_each(VALUE, int (*each)(VALUE, VALUE), VALUE);
 /* thread.c (export) */
 int ruby_thread_has_gvl_p(void); /* for ext/fiddle/closure.c */
 
+/* time.c (export) */
+void reset_leap_second_info(void);
+
 /* util.c (export) */
 extern const signed char ruby_digit36_to_number_table[];
 extern const char ruby_hexdigits[];
diff --git a/test/ruby/test_time_tz.rb b/test/ruby/test_time_tz.rb
index d138bcece1..43758d948f 100644
--- a/test/ruby/test_time_tz.rb
+++ b/test/ruby/test_time_tz.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal: false
 require 'test/unit'
+require '-test-/time'
 
 class TestTimeTZ < Test::Unit::TestCase
   has_right_tz = true
@@ -210,6 +211,7 @@ class TestTimeTZ < Test::Unit::TestCase
 
   def test_right_utc
     with_tz(tz="right/UTC") {
+      ::Bug::Time.reset_leap_second_info
       assert_time_constructor(tz, "2008-12-31 23:59:59 UTC", :utc, [2008,12,31,23,59,59])
       assert_time_constructor(tz, "2008-12-31 23:59:60 UTC", :utc, [2008,12,31,23,59,60])
       assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2008,12,31,24,0,0])
@@ -217,6 +219,31 @@ class TestTimeTZ < Test::Unit::TestCase
     }
   end if has_right_tz
 
+  def test_right_utc_switching
+    with_tz("UTC") { # ensure no leap second timezone
+      ::Bug::Time.reset_leap_second_info
+      assert_equal(4102444800, Time.utc(2100,1,1,0,0,0).to_i)
+      with_tz(tz="right/UTC") {
+        assert_time_constructor(tz, "2008-12-31 23:59:59 UTC", :utc, [2008,12,31,23,59,59])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2008,12,31,23,59,60])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2008,12,31,24,0,0])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2009,1,1,0,0,0])
+        assert_equal(4102444800, Time.utc(2100,1,1,0,0,0).to_i)
+      }
+    }
+    with_tz("right/UTC") {
+      ::Bug::Time.reset_leap_second_info
+      assert_equal(4102444827, Time.utc(2100,1,1,0,0,0).to_i)
+      with_tz(tz="UTC") {
+        assert_time_constructor(tz, "2008-12-31 23:59:59 UTC", :utc, [2008,12,31,23,59,59])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2008,12,31,23,59,60])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2008,12,31,24,0,0])
+        assert_time_constructor(tz, "2009-01-01 00:00:00 UTC", :utc, [2009,1,1,0,0,0])
+        assert_equal(4102444827, Time.utc(2100,1,1,0,0,0).to_i)
+      }
+    }
+  end if has_right_tz
+
   def test_right_america_los_angeles
     with_tz(tz="right/America/Los_Angeles") {
       assert_time_constructor(tz, "2008-12-31 15:59:59 -0800", :local, [2008,12,31,15,59,59])
@@ -281,6 +308,7 @@ class TestTimeTZ < Test::Unit::TestCase
       mesg = "#{mesg_utc}.localtime"
       define_method(gen_test_name(tz)) {
         with_tz(tz) {
+          ::Bug::Time.reset_leap_second_info
           t = nil
           assert_nothing_raised(mesg) { t = Time.utc(*u) }
           assert_equal(expected_utc, time_to_s(t), mesg_utc)
diff --git a/time.c b/time.c
index f48f0e29f3..20a514e2dc 100644
--- a/time.c
+++ b/time.c
@@ -1098,6 +1098,12 @@ init_leap_second_info(void)
     }
 }
 
+/* Use this if you want to re-run init_leap_second_info() */
+void reset_leap_second_info(void)
+{
+    this_year = 0;
+}
+
 static wideval_t
 timegmw(struct vtm *vtm)
 {
@@ -1115,7 +1121,14 @@ timegmw(struct vtm *vtm)
 
     timew = timegmw_noleapsecond(vtm);
 
-    if (wlt(rb_time_magnify(TIMET2WV(known_leap_seconds_limit)), timew)) {
+
+    if (number_of_leap_seconds_known == 0) {
+        /* When init_leap_second_info() is executed, the timezone doesn't have
+         * leap second information. Disable leap second for calculating gmtime.
+         */
+        return timew;
+    }
+    else if (wlt(rb_time_magnify(TIMET2WV(known_leap_seconds_limit)), timew)) {
         return wadd(timew, rb_time_magnify(WINT2WV(number_of_leap_seconds_known)));
     }
 
@@ -1148,7 +1161,14 @@ gmtimew(wideval_t timew, struct vtm *result)
 
     init_leap_second_info();
 
-    if (wlt(rb_time_magnify(TIMET2WV(known_leap_seconds_limit)), timew)) {
+    if (number_of_leap_seconds_known == 0) {
+        /* When init_leap_second_info() is executed, the timezone doesn't have
+         * leap second information. Disable leap second for calculating gmtime.
+         */
+        gmtimew_noleapsecond(timew, result);
+        return result;
+    }
+    else if (wlt(rb_time_magnify(TIMET2WV(known_leap_seconds_limit)), timew)) {
         timew = wsub(timew, rb_time_magnify(WINT2WV(number_of_leap_seconds_known)));
         gmtimew_noleapsecond(timew, result);
         return result;