erb.rb: frozen-string-literal safe

* lib/erb.rb (ERB#set_eoutvar): explicitly make mutable string as
  a buffer to make ERB work with --enable-frozen-string-literal.
  [ruby-core:73561] [Bug #12031]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53682 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 9 insertions, 0 deletions

diff --git a/test/erb/test_erb.rb b/test/erb/test_erb.rb
index 29fbf97686..97f45af73d 100644
--- a/test/erb/test_erb.rb
+++ b/test/erb/test_erb.rb
@@ -534,6 +534,15 @@ EOS
     EOS
     assert_equal(ans, extended_erb.new(src).result)
   end
+
+  def test_frozen_string_literal
+    bug12031 = '[ruby-core:73561] [Bug #12031]'
+    e = @erb.new("<%#encoding: us-ascii%>a")
+    e.src.sub!(/\A#(?:-\*-)?(.*)(?:-\*-)?/) {
+      '# -*- \1; frozen-string-literal: true -*-'
+    }
+    assert_equal("a", e.result, bug12031)
+  end
 end
 
 class TestERBCoreWOStrScan < TestERBCore