string.c: coderange appending to empty string

* string.c (rb_enc_cr_str_buf_cat, rb_str_append): consider an empty
  string 7bit-clean and should not discard cached coderange of string
  to be appended.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41720 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 9 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 52d0862dc9..6f9a67bb0e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Jul  1 15:03:42 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* string.c (rb_enc_cr_str_buf_cat, rb_str_append): consider an empty
+	  string 7bit-clean and should not discard cached coderange of string
+	  to be appended.
+
 Mon Jul  1 12:56:41 2013  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* eval.c (rb_using_module): activate refinements in the ancestors of
diff --git a/string.c b/string.c
index 49adca7615..581c300281 100644
--- a/string.c
+++ b/string.c
@@ -1958,7 +1958,7 @@ rb_enc_cr_str_buf_cat(VALUE str, const char *ptr, long len,
     int res_encindex;
     int str_cr, res_cr;
 
-    str_cr = ENC_CODERANGE(str);
+    str_cr = RSTRING_LEN(str) ? ENC_CODERANGE(str) : ENC_CODERANGE_7BIT;
 
     if (str_encindex == ptr_encindex) {
         if (str_cr == ENC_CODERANGE_UNKNOWN)
@@ -2095,7 +2095,8 @@ rb_str_append(VALUE str, VALUE str2)
         long len = RSTRING_LEN(str) + len2;
         enc = rb_enc_check(str, str2);
         cr = ENC_CODERANGE(str);
-        if ((cr2 = ENC_CODERANGE(str2)) > cr) cr = cr2;
+        if ((cr2 = ENC_CODERANGE(str2)) > cr || RSTRING_LEN(str) == 0)
+	    cr = cr2;
         rb_str_modify_expand(str, len2);
         memcpy(RSTRING(str)->as.heap.ptr + RSTRING(str)->as.heap.len,
                RSTRING_PTR(str2), len2+1);