parse.y, vm_eval.c: file encoding in eval

* parse.y (yycompile): store file name as String to keep the encoding.

* parse.y (rb_parser_compile_string_path, rb_parser_compile_file_path):
  new functions to pass file name as a String.

* parse.y (gettable_gen): return a copy of the original file name, not
  a copy in filesystem encoding.

* vm_eval.c (eval_string_with_cref): use Qundef instead of "(eval)".

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42230 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_eval.rb

@@ -468,4 +468,9 @@ class TestEval < Test::Unit::TestCase
     result = foo.instance_eval(&foo_pr)
     assert_equal(1, result, 'Bug #3786, Bug #3860, [ruby-core:32501]')
   end
+
+  def test_file_encoding
+    fname = "\u{3042}".encode("euc-jp")
+    assert_equal(fname, eval("__FILE__", nil, fname, 1))
+  end
 end