parse.y: should not deent concatenated string

* parse.y (xstring): reset heredoc indent after dedenting,
  so that following string literal would not be dedented.
  [ruby-core:72857] [Bug #11990]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53555 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sat Jan 16 21:16:21 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (xstring): reset heredoc indent after dedenting,
+	  so that following string literal would not be dedented.
+	  [ruby-core:72857] [Bug #11990]
+
 Sat Jan 16 17:24:24 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>
 
 	* enc/unicode.c: Artificial mapping to test buffer expansion code.

parse.y

@@ -3950,6 +3950,7 @@ xstring		: tXSTRING_BEG xstring_contents tSTRING_END
 		    /*%
 		    %*/
 			heredoc_dedent($2);
+			heredoc_indent = 0;
 		    /*%%%*/
 			if (!node) {
 			    node = NEW_XSTR(STR_NEW0());

test/ruby/test_syntax.rb

@@ -2,6 +2,14 @@
 require 'test/unit'
 
 class TestSyntax < Test::Unit::TestCase
+  using Module.new {
+    refine(Object) do
+      def `(s) #`
+        s
+      end
+    end
+  }
+
   def assert_syntax_files(test)
     srcdir = File.expand_path("../../..", __FILE__)
     srcdir = File.join(srcdir, test)
@@ -493,7 +501,7 @@ e"
   end
 
   def assert_dedented_heredoc(expect, result, mesg = "")
-    %w[eos "eos" 'eos'].each do |eos|
+    %w[eos "eos" 'eos' `eos`].each do |eos|
       assert_equal(eval("<<-#{eos}\n#{expect}eos\n"),
                    eval("<<~#{eos}\n#{result}eos\n"),
                    message(mesg) {"with #{eos}"})
@@ -587,6 +595,10 @@ e"
                    eval("<<~#{eos} '  y'\n  x\neos\n"),
                    "#{bug11990} with #{eos}")
     end
+    %w[eos "eos" 'eos' `eos`].each do |eos|
+      _, expect = eval("[<<~#{eos}, '  x']\n""  y\n""eos\n")
+      assert_equal('  x', expect, bug11990)
+    end
   end
 
   def test_lineno_after_heredoc