Merge pull request #35659 from rails/fix-time-advance-with-historical-dates

Fix Time#advance to work with dates before 1001-03-07

activesupport/CHANGELOG.md

+*   Fix `Time#advance` to work with dates before 1001-03-07
+
+    Before:
+    
+        Time.utc(1001, 3, 6).advance(years: -1) # => 1000-03-05 00:00:00 UTC
+    
+    After
+    
+        Time.utc(1001, 3, 6).advance(years: -1) # => 1000-03-06 00:00:00 UTC
+
+    Note that this doesn't affect `DateTime#advance` as that doesn't use a proleptic calendar.
+
+    *Andrew White*
+
 *   In Zeitwerk mode, engines are now managed by the `main` autoloader. Engines may reference application constants, if the application is reloaded and we do not reload engines, they won't use the reloaded application code.
 
     *Xavier Noria*

activesupport/lib/active_support/core_ext/time/calculations.rb

@@ -170,8 +170,7 @@ def advance(options)
       options[:hours] = options.fetch(:hours, 0) + 24 * partial_days
     end
 
-    d = to_date.advance(options)
-    d = d.gregorian if d.julian?
+    d = to_date.gregorian.advance(options)
     time_advanced_by_date = change(year: d.year, month: d.month, day: d.day)
     seconds_to_advance = \
       options.fetch(:seconds, 0) +

activesupport/test/core_ext/time_ext_test.rb

@@ -514,6 +514,8 @@ def test_advance_gregorian_proleptic
     assert_equal Time.local(1582, 10, 15, 15, 15, 10), Time.local(1582, 10, 14, 15, 15, 10).advance(days: 1)
     assert_equal Time.local(1582, 10, 5, 15, 15, 10), Time.local(1582, 10, 4, 15, 15, 10).advance(days: 1)
     assert_equal Time.local(1582, 10, 4, 15, 15, 10), Time.local(1582, 10, 5, 15, 15, 10).advance(days: -1)
+    assert_equal Time.local(999, 10, 4, 15, 15, 10), Time.local(1000, 10, 4, 15, 15, 10).advance(years: -1)
+    assert_equal Time.local(1000, 10, 4, 15, 15, 10), Time.local(999, 10, 4, 15, 15, 10).advance(years: 1)
   end
 
   def test_last_week