From 0c6ddbe7b0056cb5c17d6b483c0e5a7cbd596b97 Mon Sep 17 00:00:00 2001
From: Riley Lynch <oss+rails@teleological.net>
Date: Wed, 15 May 2013 08:59:52 -0400
Subject: Maintain proleptic gregorian in Time#advance

Time#advance uses Time#to_date and Date#advance to calculate a new date.
The Date object returned by Time#to_date is constructed with the assumption
that the Time object represents a proleptic gregorian date, but it is
configured to observe the default julian calendar reform date (2299161j)
for purposes of calculating month, date and year:

  Time.new(1582, 10, 4).to_date.to_s           # => "1582-09-24"
  Time.new(1582, 10, 4).to_date.gregorian.to_s # => "1582-10-04"

This patch ensures that when the intermediate Date object is advanced
to yield a new Date object, that the Time object for return is contructed
with a proleptic gregorian month, date and year.
---
 activesupport/lib/active_support/core_ext/time/calculations.rb | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

(limited to 'activesupport/lib')

diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index a3ce7dbe3f..e86332ba3a 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -110,10 +110,11 @@ class Time
     end
   end
 
-  # Uses Date to provide precise Time calculations for years, months, and days.
-  # The +options+ parameter takes a hash with any of these keys: <tt>:years</tt>,
-  # <tt>:months</tt>, <tt>:weeks</tt>, <tt>:days</tt>, <tt>:hours</tt>,
-  # <tt>:minutes</tt>, <tt>:seconds</tt>.
+  # Uses Date to provide precise Time calculations for years, months, and days
+  # according to the proleptic Gregorian calendar. The +options+ parameter
+  # takes a hash with any of these keys: <tt>:years</tt>, <tt>:months</tt>,
+  # <tt>:weeks</tt>, <tt>:days</tt>, <tt>:hours</tt>, <tt>:minutes</tt>,
+  # <tt>:seconds</tt>.
   def advance(options)
     unless options[:weeks].nil?
       options[:weeks], partial_weeks = options[:weeks].divmod(1)
@@ -126,6 +127,7 @@ class Time
     end
 
     d = to_date.advance(options)
+    d = d.gregorian if d.julian?
     time_advanced_by_date = change(:year => d.year, :month => d.month, :day => d.day)
     seconds_to_advance = \
       options.fetch(:seconds, 0) +
-- 
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