merges r20804 from trunk into ruby_1_9_1.

* string.c (rb_str_hash): gets rid of collisions between different
  encoding strings.  [ruby-core:20526]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@20834 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 1 deletions

diff --git a/string.c b/string.c
index 1eac1bda3c..e0efa04775 100644
--- a/string.c
+++ b/string.c
@@ -2014,7 +2014,11 @@ rb_memhash(const void *ptr, long len)
 int
 rb_str_hash(VALUE str)
 {
-    return rb_memhash((const void *)RSTRING_PTR(str), RSTRING_LEN(str));
+    int e = ENCODING_GET(str);
+    if (e) {
+	if (rb_enc_str_asciionly_p(str)) e = 0;
+    }
+    return rb_memhash((const void *)RSTRING_PTR(str), RSTRING_LEN(str)) ^ e;
 }
 
 int