Allow a SortedSet to be frozen and still functional [Bug #12091]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60298 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/set.rb

@@ -723,6 +723,11 @@ class SortedSet < Set
             (@keys = @hash.keys).sort! unless @keys
             @keys
           end
+
+          def freeze
+            to_a
+            super
+          end
         END
       end
       module_eval {

test/test_set.rb

@@ -829,6 +829,45 @@ class TC_SortedSet < Test::Unit::TestCase
     set << 42
     assert_equal(7, e.size)
   end
+
+  def test_freeze
+    orig = set = SortedSet[3,2,1]
+    assert_equal false, set.frozen?
+    set << 4
+    assert_same orig, set.freeze
+    assert_equal true, set.frozen?
+    assert_raise(RuntimeError) {
+      set << 5
+    }
+    assert_equal 4, set.size
+
+    # https://bugs.ruby-lang.org/issues/12091
+    assert_nothing_raised {
+      assert_equal [1,2,3,4], set.to_a
+    }
+  end
+
+  def test_freeze_dup
+    set1 = SortedSet[1,2,3]
+    set1.freeze
+    set2 = set1.dup
+
+    assert_not_predicate set2, :frozen?
+    assert_nothing_raised {
+      set2.add 4
+    }
+  end
+
+  def test_freeze_clone
+    set1 = SortedSet[1,2,3]
+    set1.freeze
+    set2 = set1.clone
+
+    assert_predicate set2, :frozen?
+    assert_raise(RuntimeError) {
+      set2.add 5
+    }
+  end
 end
 
 class TC_Enumerable < Test::Unit::TestCase