rdoc/text.rb: fix infinite loop

* lib/rdoc/text.rb (expand_tabs): get rid of infinite loop with
  CR.  should check if substitution occurred too.
  [ruby-dev:48813] [Bug #10732]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49223 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon Jan 12 18:01:24 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/rdoc/text.rb (expand_tabs): get rid of infinite loop with
+	  CR.  should check if substitution occurred too.
+	  [ruby-dev:48813] [Bug #10732]
+
 Mon Jan 12 16:45:46 2015  Seiei Higa  <hanachin@gmail.com>
 
 	* vm_method.c (rb_alias): raise a NameError when creating alias to

lib/rdoc/text.rb

@@ -68,11 +68,11 @@ module RDoc::Text
     expanded = []
 
     text.each_line do |line|
-      line.gsub!(/^((?:.{8})*?)([^\t\r\n]{0,7})\t/) do
+      nil while line.gsub!(/(?:\G|\r)((?:.{8})*?)([^\t\r\n]{0,7})\t/) do
         r = "#{$1}#{$2}#{' ' * (8 - $2.size)}"
         r.force_encoding text.encoding if Object.const_defined? :Encoding
         r
-      end until line !~ /\t/
+      end
 
       expanded << line
     end

test/rdoc/test_rdoc_text.rb

@@ -56,6 +56,9 @@ class TestRDocText < RDoc::TestCase
 
     assert_equal('.               .',
                  expand_tabs(".\t\t."), 'dot tab tab dot')
+
+    assert_equal('a       a',
+                 Timeout.timeout(1) {expand_tabs("\ra\ta")}, "carriage return")
   end
 
   def test_expand_tabs_encoding