* io.c (io_encoding_set): ignore second argument when external and

  internal are same. [ruby-dev:37939]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@22146 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 9 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 53dad3b76f..43960efe6b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Feb  9 11:31:09 2009  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* io.c (io_encoding_set): ignore second argument when external and
+	  internal are same. [ruby-dev:37939]
+
 Mon Feb  9 09:05:12 2009  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/option.c (inspect_local_peercred): check version.
diff --git a/io.c b/io.c
index 9cac7631c4..6f0b9d034f 100644
--- a/io.c
+++ b/io.c
@@ -7024,6 +7024,10 @@ io_encoding_set(rb_io_t *fptr, VALUE v1, VALUE v2, VALUE opt)
 	    }
 	    else
 		enc = rb_to_encoding(v2);
+	    if (enc == enc2) {
+		/* Special case - "-" => no transcoding */
+		enc2 = NULL;
+	    }
 	}
 	else
 	    enc = rb_to_encoding(v2);