* encoding.c (rb_enc_compatible): return ASCII-8BIT even if 2nd string

is ascii only string. [ruby-core:42354] [Bug #5968]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34433 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Mon Feb  6 00:16:27 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* encoding.c (rb_enc_compatible): return ASCII-8BIT even if 2nd string
+	  is ascii only string. [ruby-core:42354] [Bug #5968]
+
 Fri Feb  3 07:16:47 2012  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/webrick.rb:  Moved proxy rewriting to WEBrick::HTTPProxy.

encoding.c

@@ -812,7 +812,6 @@ rb_enc_compatible(VALUE str1, VALUE str2)
 		if (cr2 == ENC_CODERANGE_7BIT) return enc1;
 	    }
 	    if (cr2 == ENC_CODERANGE_7BIT) {
-		if (idx1 == ENCINDEX_ASCII) return enc2;
 		return enc1;
 	    }
 	}

test/ruby/test_encoding.rb

@@ -109,5 +109,8 @@ class TestEncoding < Test::Unit::TestCase
     ua = "abc".force_encoding(Encoding::UTF_8)
     assert_equal(Encoding::UTF_8, Encoding.compatible?(ua, :abc))
     assert_equal(nil, Encoding.compatible?(ua, 1))
+    bin = "a".force_encoding(Encoding::ASCII_8BIT)
+    asc = "b".force_encoding(Encoding::US_ASCII)
+    assert_equal(Encoding::ASCII_8BIT, Encoding.compatible?(bin, asc))
   end
 end