* io.c (io_encoding_set): always warn if external encoding and internal

encoding are identical. [ruby-core:40727] [Bug ruby#5568] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34997 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
funny-falcon · Mar 13, 2012 · db83618 · db83618
1 parent 272d72e
commit db83618
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diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Mar 13 12:37:53 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* io.c (io_encoding_set): always warn if external encoding and internal
+	  encoding are identical. [ruby-core:40727] [Bug #5568]
+
 Tue Mar 13 12:37:03 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	Bug #5350

diff --git a/io.c b/io.c
@@ -8743,11 +8743,22 @@ io_encoding_set(rb_io_t *fptr, VALUE v1, VALUE v2, VALUE opt)
 		enc = find_encoding(v2);
 	    if (enc == enc2) {
 		/* Special case - "-" => no transcoding */
+		VALUE tmp1 = rb_check_string_type(v1);
+		rb_warn("Ignoring internal encoding %s: it is identical to external encoding %s",
+			StringValueCStr(tmp), NIL_P(tmp1) ? rb_enc_name(enc) : StringValueCStr(tmp1));
 		enc2 = NULL;
 	    }
 	}
-	else
+	else {
 	    enc = find_encoding(v2);
+	    if (enc == enc2) {
+		/* Special case - "-" => no transcoding */
+		VALUE tmp1 = rb_check_string_type(v1);
+		rb_warn("Ignoring internal encoding %s: it is identical to external encoding %s",
+			rb_enc_name(enc), NIL_P(tmp1) ? rb_enc_name(enc) : StringValueCStr(tmp1));
+		enc2 = NULL;
+	    }
+	}
 	SET_UNIVERSAL_NEWLINE_DECORATOR_IF_ENC2(enc2, ecflags);
 	ecflags = rb_econv_prepare_options(opt, &ecopts, ecflags);
     }

diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
@@ -984,6 +984,32 @@ def test_set_encoding_invalid
          end)
   end
 
+  def test_set_encoding_identical
+    bug5568 = '[ruby-core:40727]'
+    open(__FILE__, "r") do |f|
+      assert_warn(/Ignoring internal encoding euc-jp: it is identical to external encoding eucjp/, bug5568) {
+        f.set_encoding("eucjp:euc-jp")
+      }
+      assert_warn(/Ignoring internal encoding euc-jp: it is identical to external encoding eucjp/, bug5568) {
+        f.set_encoding("eucjp", "euc-jp")
+      }
+      assert_warn(/Ignoring internal encoding euc-jp: it is identical to external encoding EUC-JP/, bug5568) {
+        f.set_encoding(Encoding::EUC_JP, "euc-jp")
+      }
+      assert_warn(/Ignoring internal encoding EUC-JP: it is identical to external encoding eucjp/, bug5568) {
+        f.set_encoding("eucjp", Encoding::EUC_JP)
+      }
+      assert_warn(/Ignoring internal encoding EUC-JP: it is identical to external encoding EUC-JP/, bug5568) {
+        f.set_encoding(Encoding::EUC_JP, Encoding::EUC_JP)
+      }
+      nonstr = Object.new
+      def nonstr.to_str; "eucjp"; end
+      assert_warn(/Ignoring internal encoding eucjp: it is identical to external encoding eucjp/, bug5568) {
+        f.set_encoding(nonstr, nonstr)
+      }
+    end
+  end
+
   def test_set_encoding_undef
     pipe(proc do |w|
            w << "\ufffd"