Upgrade WinTZ utility to use TZInfo-2.0 (#7521)

Merge pull request 7521

Gemfile

@@ -80,8 +80,12 @@ group :jekyll_optional_dependencies do
     gem "yajl-ruby", "~> 1.4"
   end
 
-  # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
-  gem "tzinfo-data", :platforms => [:mingw, :mswin, :x64_mingw, :jruby]
+  # Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem
+  # and associated library
+  install_if -> { RUBY_PLATFORM =~ %r!mingw|mswin|java! } do
+    gem "tzinfo", "~> 2.0"
+    gem "tzinfo-data"
+  end
 end
 
 #

docs/_docs/upgrading/3-to-4.md

@@ -46,6 +46,21 @@ you can invoke *`Liquid::Template`* directly:
   + template = Liquid::Template.parse(content)
   ```
 
+
+### Timezone in Windows
+
+Timezone handling for Jekyll on Windows now requires `tzinfo-2.0` and above.
+Simply add / update the gem listing in your `Gemfile`:
+
+```ruby
+# Gemfile
+
+# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
+# and associated library.
+gem "tzinfo-data", platforms: [:mingw, :mswin, :x64_mingw, :jruby]
+gem "tzinfo", "~> 2.0"
+```
+
 ---
 
 ### Exclusion changes

lib/jekyll/commands/new.rb

@@ -88,8 +88,14 @@ module Jekyll
             group :jekyll_plugins do
               gem "jekyll-feed", "~> 0.6"
             end
-            # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
-            gem "tzinfo-data", platforms: [:mingw, :mswin, :x64_mingw, :jruby]
+
+            # Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem
+            # and associated library.
+            install_if -> { RUBY_PLATFORM =~ %r!mingw|mswin|java! } do
+              gem "tzinfo", "~> 2.0"
+              gem "tzinfo-data"
+            end
+
             # Performance-booster for watching directories on Windows
             gem "wdm", "~> 0.1.1", :install_if => Gem.win_platform?
 

lib/jekyll/utils/win_tz.rb

@@ -13,16 +13,20 @@ module Jekyll
       # Returns a string that ultimately re-defines ENV["TZ"] in Windows
       def calculate(timezone)
         External.require_with_graceful_fail("tzinfo") unless defined?(TZInfo)
-        tz = TZInfo::Timezone.get(timezone)
-        difference = Time.now.to_i - tz.now.to_i
+        difference = TZInfo::Timezone.get(timezone).now.utc_offset
         #
         # POSIX style definition reverses the offset sign.
         #   e.g. Eastern Standard Time (EST) that is 5Hrs. to the 'west' of Prime Meridian
         #   is denoted as:
         #     EST+5 (or) EST+05:00
         # Reference: http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
-        sign = difference.negative? ? "-" : "+"
-        offset = sign == "-" ? "+" : "-" unless difference.zero?
+        if difference.negative?
+          offset = "-"
+          sign   = "+"
+        else
+          offset = "+"
+          sign   = "-"
+        end
         #
         # convert the difference (in seconds) to hours, as a rational number, and perform
         # a modulo operation on it.