array.c: return first unique element in Array#uniq

* array.c (ary_add_hash): Fix consistency issue between Array#uniq and
  Array#uniq! [Bug #9340] [ruby-core:59457]
* test/ruby/test_array.rb (class TestArray): regression test for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44512 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/array.c b/array.c
index c4869789e5..775fb243bd 100644
--- a/array.c
+++ b/array.c
@@ -3908,7 +3908,9 @@ ary_add_hash(VALUE hash, VALUE ary)
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
 	VALUE elt = RARRAY_AREF(ary, i);
-	rb_hash_aset(hash, elt, elt);
+	if (rb_hash_lookup2(hash, elt, Qundef) == Qundef) {
+	    rb_hash_aset(hash, elt, elt);
+	}
     }
     return hash;
 }