Merge psych-3.0.2 from ruby/psych.

It version changed fallback option to keywoad argument
  on `Yaml.load` method. It break backword compatiblity.

  see detailed discuttion: https://github.com/ruby/psych/issues/340

From: SHIBATA Hiroshi <hsbt@ruby-lang.org>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61336 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/psych/lib/psych.rb

@@ -259,8 +259,8 @@ module Psych
   #   Psych.load("---\n foo: bar")                         # => {"foo"=>"bar"}
   #   Psych.load("---\n foo: bar", symbolize_names: true)  # => {:foo=>"bar"}
   #
-  def self.load yaml, filename = nil, fallback = false, symbolize_names: false
-    result = parse(yaml, filename, fallback)
+  def self.load yaml, filename = nil, fallback: false, symbolize_names: false
+    result = parse(yaml, filename, fallback: fallback)
     result = result.to_ruby if result
     symbolize_names!(result) if symbolize_names
     result
@@ -300,6 +300,16 @@ module Psych
   #
   # A Psych::BadAlias exception will be raised if the yaml contains aliases
   # but the +aliases+ parameter is set to false.
+  #
+  # +filename+ will be used in the exception message if any exception is raised
+  # while parsing.
+  #
+  # When the optional +symbolize_names+ keyword argument is set to a
+  # true value, returns symbols for keys in Hash objects (default: strings).
+  #
+  #   Psych.safe_load("---\n foo: bar")                         # => {"foo"=>"bar"}
+  #   Psych.safe_load("---\n foo: bar", symbolize_names: true)  # => {:foo=>"bar"}
+  #
   def self.safe_load yaml, whitelist_classes = [], whitelist_symbols = [], aliases = false, filename = nil, symbolize_names: false
     result = parse(yaml, filename)
     return unless result
@@ -336,7 +346,7 @@ module Psych
   #   end
   #
   # See Psych::Nodes for more information about YAML AST.
-  def self.parse yaml, filename = nil, fallback = false
+  def self.parse yaml, filename = nil, fallback: false
     parse_stream(yaml, filename) do |node|
       return node
     end
@@ -483,9 +493,9 @@ module Psych
   # Load the document contained in +filename+.  Returns the yaml contained in
   # +filename+ as a Ruby object, or if the file is empty, it returns
   # the specified default return value, which defaults to an empty Hash
-  def self.load_file filename, fallback = false
+  def self.load_file filename, fallback: false
     File.open(filename, 'r:bom|utf-8') { |f|
-      self.load f, filename, FALLBACK.new(fallback)
+      self.load f, filename, fallback: FALLBACK.new(fallback)
     }
   end
 

ext/psych/lib/psych/versions.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 module Psych
   # The version is Psych you're using
-  VERSION = '3.0.0'
+  VERSION = '3.0.2'
 
   if RUBY_ENGINE == 'jruby'
     DEFAULT_SNAKEYAML_VERSION = '1.18'.freeze

ext/psych/psych.gemspec

@@ -3,10 +3,10 @@
 
 Gem::Specification.new do |s|
   s.name = "psych"
-  s.version = "3.0.0"
+  s.version = "3.0.2"
   s.authors = ["Aaron Patterson", "SHIBATA Hiroshi", "Charles Oliver Nutter"]
   s.email = ["aaron@tenderlovemaking.com", "hsbt@ruby-lang.org", "headius@headius.com"]
-  s.date = "2017-12-01"
+  s.date = "2017-12-04"
   s.summary = "Psych is a YAML parser and emitter"
   s.description = <<-DESCRIPTION
 Psych is a YAML parser and emitter. Psych leverages libyaml[http://pyyaml.org/wiki/LibYAML]
@@ -41,7 +41,7 @@ DESCRIPTION
   s.rdoc_options = ["--main", "README.md"]
   s.extra_rdoc_files = ["CHANGELOG.rdoc", "README.md"]
 
-  s.required_ruby_version = Gem::Requirement.new(">= 1.9.2")
+  s.required_ruby_version = Gem::Requirement.new(">= 2.2.2")
   s.rubygems_version = "2.5.1"
   s.required_rubygems_version = Gem::Requirement.new(">= 0")
 

test/psych/test_psych.rb

@@ -146,7 +146,7 @@ class TestPsych < Psych::TestCase
 
   def test_load_file_with_fallback
     Tempfile.create(['empty', 'yml']) {|t|
-      assert_equal Hash.new, Psych.load_file(t.path, Hash.new)
+      assert_equal Hash.new, Psych.load_file(t.path, fallback: Hash.new)
     }
   end