* io.c (rb_io_ext_int_to_encs): ignore internal encoding if external

encoding is ASCII-8BIT. [Bug #8342]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40610 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed May  8 17:43:55 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* io.c (rb_io_ext_int_to_encs): ignore internal encoding if external
+	  encoding is ASCII-8BIT. [Bug #8342]
+
 Wed May  8 13:49:38 2013  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/json/generator/generator.c (isArrayOrObject): cast char to

NEWS

@@ -39,6 +39,10 @@ with all sufficient information, see the ChangeLog file.
 
 === Core classes compatibility issues (excluding feature bug fixes)
 
+* IO
+  * incompatible changes:
+    * open ignore internal encoding if external encoding is ASCII-8BIT.
+
 * Module#ancestors
 
   The ancestors of a singleton class now include singleton classes,

io.c

@@ -4868,9 +4868,13 @@ rb_io_ext_int_to_encs(rb_encoding *ext, rb_encoding *intern, rb_encoding **enc,
 	ext = rb_default_external_encoding();
 	default_ext = 1;
     }
-    if (intern == NULL && ext != rb_ascii8bit_encoding())
-	/* If external is ASCII-8BIT, no default transcoding */
+    if (ext == rb_ascii8bit_encoding()) {
+	/* If external is ASCII-8BIT, no transcoding */
+	intern = NULL;
+    }
+    else if (intern == NULL) {
 	intern = rb_default_internal_encoding();
+    }
     if (intern == NULL || intern == (rb_encoding *)Qnil ||
 	(!(fmode & FMODE_SETENC_BY_BOM) && (intern == ext))) {
 	/* No internal encoding => use external + no transcoding */

test/ruby/test_io_m17n.rb

@@ -105,6 +105,42 @@ EOT
     }
   end
 
+  def test_open_r_ascii8bit
+    with_tmpdir {
+      generate_file('tmp', "")
+      EnvUtil.with_default_external(Encoding::ASCII_8BIT) do
+        EnvUtil.with_default_internal(Encoding::UTF_8) do
+          open("tmp", "r") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+          open("tmp", "r:ascii-8bit") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+          open("tmp", "r:ascii-8bit:utf-16") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+        end
+        EnvUtil.with_default_internal(nil) do
+          open("tmp", "r") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+          open("tmp", "r:ascii-8bit") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+          open("tmp", "r:ascii-8bit:utf-16") {|f|
+            assert_equal(Encoding::ASCII_8BIT, f.external_encoding)
+            assert_equal(nil, f.internal_encoding)
+          }
+        end
+      end
+    }
+  end
+
   def test_open_r_enc_in_opt
     with_tmpdir {
       generate_file('tmp', "")