check ar_table after `#hash` call

ar_table can be converted to st_table just after `ar_do_hash()`
function which calls `#hash` method. We need to check
the representation to detect this mutation.
[Bug #16676]

(cherry picked from commit 4c019f5a626523e99e2827ed917802e3097c380d)

1 files changed, 58 insertions, 0 deletions

diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 0f6377cf55..7832466ffb 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -1764,4 +1764,62 @@ class TestHash < Test::Unit::TestCase
     assert_equal(1, check_flagged_hash(*[hash]))
     assert_raise(TypeError) { Hash.ruby2_keywords_hash(1) }
   end
+
+  def test_ar2st
+    # insert
+    obj = Object.new
+    obj.instance_variable_set(:@h, h = {})
+    def obj.hash
+      10.times{|i| @h[i] = i}
+      0
+    end
+    def obj.inspect
+      'test'
+    end
+    h[obj] = true
+    assert_equal '{0=>0, 1=>1, 2=>2, 3=>3, 4=>4, 5=>5, 6=>6, 7=>7, 8=>8, 9=>9, test=>true}', h.inspect
+
+    # delete
+    obj = Object.new
+    obj.instance_variable_set(:@h, h = {})
+    def obj.hash
+      10.times{|i| @h[i] = i}
+      0
+    end
+    def obj.inspect
+      'test'
+    end
+    def obj.eql? other
+      other.class == Object
+    end
+    obj2 = Object.new
+    def obj2.hash
+      0
+    end
+
+    h[obj2] = true
+    h.delete obj
+    assert_equal '{0=>0, 1=>1, 2=>2, 3=>3, 4=>4, 5=>5, 6=>6, 7=>7, 8=>8, 9=>9}', h.inspect
+
+    # lookup
+    obj = Object.new
+    obj.instance_variable_set(:@h, h = {})
+    def obj.hash
+      10.times{|i| @h[i] = i}
+      0
+    end
+    def obj.inspect
+      'test'
+    end
+    def obj.eql? other
+      other.class == Object
+    end
+    obj2 = Object.new
+    def obj2.hash
+      0
+    end
+
+    h[obj2] = true
+    assert_equal true, h[obj]
+  end
 end