* string.c (rb_str_buf_append): fix append itself.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14941 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Tue Jan  8 07:56:11 2008  Tanaka Akira  <akr@fsij.org>
+
+	* string.c (rb_str_buf_append): fix append itself.
+
 Tue Jan  8 01:13:50 2008  Tanaka Akira  <akr@fsij.org>
 
 	* string.c (STR_ENC_GET): defined.  same as rb_enc_get without

string.c

@@ -1166,7 +1166,13 @@ rb_enc_str_buf_cat(VALUE str, const char *ptr, long len, rb_encoding *ptr_enc)
 VALUE
 rb_str_buf_append(VALUE str, VALUE str2)
 {
-    int str2_cr = ENC_CODERANGE(str2);
+    int str2_cr;
+
+    if (str == str2) {
+        str2 = rb_str_dup(str2);
+    }
+
+    str2_cr = ENC_CODERANGE(str2);
 
     rb_enc_cr_str_buf_cat(str, RSTRING_PTR(str2), RSTRING_LEN(str2),
         ENCODING_GET(str2), str2_cr, &str2_cr);

test/ruby/test_string.rb

@@ -170,6 +170,12 @@ class TestString < Test::Unit::TestCase
   def test_LSHIFT # '<<'
     assert_equal(S("world!"), S("world") << 33)
     assert_equal(S("world!"), S("world") << S('!'))
+
+    s = "a"
+    10.times {|i|
+      s << s
+      assert_equal("a" * (2<<i), s)
+    }
   end
 
   def test_MATCH # '=~'