optparse.rb: case-sensitive candidate

* lib/optparse.rb (candidate): short options are case-sensitive by
  the default, should not match case-different options..
  https://github.com/mernen/completion-ruby/pull/9#issuecomment-317287946

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59412 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/optparse.rb

@@ -1744,16 +1744,16 @@ XXX
   def candidate(word)
     list = []
     case word
+    when '-'
+      long = short = true
     when /\A--/
       word, arg = word.split(/=/, 2)
       argpat = Completion.regexp(arg, false) if arg and !arg.empty?
       long = true
-    when /\A-(!-)/
-      short = true
     when /\A-/
-      long = short = true
+      short = true
     end
-    pat = Completion.regexp(word, true)
+    pat = Completion.regexp(word, long)
     visit(:each_option) do |opt|
       next unless Switch === opt
       opts = (long ? opt.long : []) + (short ? opt.short : [])

test/optparse/test_bash_completion.rb

@@ -40,4 +40,9 @@ class TestOptionParser::BashCompletion < Test::Unit::TestCase
   def test_long_for_option_complete
     assert_equal(%w[hello help], @opt.candidate("--for=h"))
   end
+
+  def test_case_sensitive
+    @opt.define("-Z") {}
+    assert_equal(%w[-z], @opt.candidate("-z"))
+  end
 end