From dd439bfbda2a39b305b13f00c40d07c6a8c46d8c Mon Sep 17 00:00:00 2001
From: Lars Kanis <kanis@comcard.de>
Date: Mon, 31 Jul 2017 14:59:11 +0200
Subject: [PATCH] Use duktape gem as default JS engine on Windows-MINGW and
 MS-Visual-C builds

The fallback javascript engine on Windows is Windows Script Host (JScript).
However this engine isn't able to process the default assets, because it supports
ES3 only but the coffeescript compiler requires ES5.

Fixes #30014
---
 railties/lib/rails/generators/app_base.rb      | 2 ++
 railties/test/generators/app_generator_test.rb | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/railties/lib/rails/generators/app_base.rb b/railties/lib/rails/generators/app_base.rb
index 760cb2f81e..4899a63917 100644
--- a/railties/lib/rails/generators/app_base.rb
+++ b/railties/lib/rails/generators/app_base.rb
@@ -348,6 +348,8 @@ module Rails
         comment = "See https://github.com/rails/execjs#readme for more supported runtimes"
         if defined?(JRUBY_VERSION)
           GemfileEntry.version "therubyrhino", nil, comment
+        elsif RUBY_PLATFORM =~ /mingw|mswin/
+          GemfileEntry.version "duktape", nil, comment
         else
           GemfileEntry.new "mini_racer", nil, comment, { platforms: :ruby }, true
         end
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index ffdee3a6b5..284c200e35 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -521,6 +521,8 @@ class AppGeneratorTest < Rails::Generators::TestCase
     run_generator
     if defined?(JRUBY_VERSION)
       assert_gem "therubyrhino"
+    elsif RUBY_PLATFORM =~ /mingw|mswin/
+      assert_gem "duktape"
     else
       assert_file "Gemfile", /# gem 'mini_racer', platforms: :ruby/
     end