hash.c: reject should return a plain hash

* hash.c (rb_hash_reject): return a plain hash, without copying
  the class, default value, instance variables, and taintedness.
  they had been copied just by accident.
  [ruby-core:59045] [Bug #9223]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44137 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 63 insertions, 16 deletions

diff --git a/ChangeLog b/ChangeLog
index edeab0d141..23da1f6a2d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Wed Dec 11 16:01:26 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* hash.c (rb_hash_reject): return a plain hash, without copying
+	  the class, default value, instance variables, and taintedness.
+	  they had been copied just by accident.
+	  [ruby-core:59045] [Bug #9223]
+
 Wed Dec 11 15:36:15 2013  Aman Gupta <ruby@tmm1.net>
 
 	* compile.c (iseq_specialized_instruction): emit opt_aset instruction
diff --git a/hash.c b/hash.c
index 4273aec45a..83c243fbf0 100644
--- a/hash.c
+++ b/hash.c
@@ -1095,37 +1095,39 @@ rb_hash_reject_bang(VALUE hash)
 }
 
 static int
-reject_i(VALUE key, VALUE value, VALUE hash)
+reject_i(VALUE key, VALUE value, VALUE result)
 {
     if (!RTEST(rb_yield_values(2, key, value))) {
-	rb_hash_aset(hash, key, value);
+	rb_hash_aset(result, key, value);
     }
     return ST_CONTINUE;
 }
 
 /*
  *  call-seq:
- *     hsh.reject {| key, value | block }  -> a_hash
- *     hsh.reject                          -> an_enumerator
+ *     hsh.reject {|key, value| block}   -> a_hash
+ *     hsh.reject                        -> an_enumerator
+ *
+ *  Returns a new hash consisting of entries for which the block returns false.
  *
- *  Same as <code>Hash#delete_if</code>, but works on (and returns) a
- *  copy of the <i>hsh</i>. Equivalent to
- *  <code><i>hsh</i>.dup.delete_if</code>.
+ *  If no block is given, an enumerator is returned instead.
  *
+ *     h = { "a" => 100, "b" => 200, "c" => 300 }
+ *     h.reject {|k,v| k < "b"}  #=> {"b" => 200, "c" => 300}
+ *     h.reject {|k,v| v > 100}  #=> {"a" => 100}
  */
 
-static VALUE
+VALUE
 rb_hash_reject(VALUE hash)
 {
-    VALUE ret;
+    VALUE result;
 
     RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
-    ret = hash_alloc(rb_obj_class(hash));
-    OBJ_INFECT(ret, hash);
+    result = rb_hash_new();
     if (!RHASH_EMPTY_P(hash)) {
-	rb_hash_foreach(hash, reject_i, ret);
+	rb_hash_foreach(hash, reject_i, result);
     }
-    return ret;
+    return result;
 }
 
 /*
@@ -1154,8 +1156,9 @@ rb_hash_values_at(int argc, VALUE *argv, VALUE hash)
 static int
 select_i(VALUE key, VALUE value, VALUE result)
 {
-    if (RTEST(rb_yield_values(2, key, value)))
+    if (RTEST(rb_yield_values(2, key, value))) {
 	rb_hash_aset(result, key, value);
+    }
     return ST_CONTINUE;
 }
 
@@ -1180,7 +1183,9 @@ rb_hash_select(VALUE hash)
 
     RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
     result = rb_hash_new();
-    rb_hash_foreach(hash, select_i, result);
+    if (!RHASH_EMPTY_P(hash)) {
+	rb_hash_foreach(hash, select_i, result);
+    }
     return result;
 }
 
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 8c8ce6d7c3..208e628a6b 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -539,6 +539,8 @@ class TestHash < Test::Unit::TestCase
   end
 
   def test_reject
+    assert_equal({3=>4,5=>6}, @cls[1=>2,3=>4,5=>6].reject {|k, v| k + v < 7 })
+
     base = @cls[ 1 => 'one', 2 => false, true => 'true', 'cat' => 99 ]
     h1   = @cls[ 1 => 'one', 2 => false, true => 'true' ]
     h2   = @cls[ 2 => false, 'cat' => 99 ]
@@ -556,7 +558,14 @@ class TestHash < Test::Unit::TestCase
     assert_equal(h3, h.reject {|k,v| v })
     assert_equal(base, h)
 
-    assert_predicate(h.taint.reject {true}, :tainted?)
+    h.instance_variable_set(:@foo, :foo)
+    h.default = 42
+    h.taint
+    h = h.reject {false}
+    assert_instance_of(Hash, h)
+    assert_not_predicate(h, :tainted?)
+    assert_nil(h.default)
+    assert_not_send([h, :instance_variable_defined?, :@foo])
   end
 
   def test_reject!
@@ -816,6 +825,32 @@ class TestHash < Test::Unit::TestCase
 
   def test_select
     assert_equal({3=>4,5=>6}, @cls[1=>2,3=>4,5=>6].select {|k, v| k + v >= 7 })
+
+    base = @cls[ 1 => 'one', '2' => false, true => 'true', 'cat' => 99 ]
+    h1   = @cls[ '2' => false, 'cat' => 99 ]
+    h2   = @cls[ 1 => 'one', true => 'true' ]
+    h3   = @cls[ 1 => 'one', true => 'true', 'cat' => 99 ]
+
+    h = base.dup
+    assert_equal(h, h.select { true })
+    assert_equal(@cls[], h.select { false })
+
+    h = base.dup
+    assert_equal(h1, h.select {|k,v| k.instance_of?(String) })
+
+    assert_equal(h2, h.select {|k,v| v.instance_of?(String) })
+
+    assert_equal(h3, h.select {|k,v| v })
+    assert_equal(base, h)
+
+    h.instance_variable_set(:@foo, :foo)
+    h.default = 42
+    h.taint
+    h = h.select {true}
+    assert_instance_of(Hash, h)
+    assert_not_predicate(h, :tainted?)
+    assert_nil(h.default)
+    assert_not_send([h, :instance_variable_defined?, :@foo])
   end
 
   def test_select!