Make Object#method and Module#instance_method not skip ZSUPER methods

Based on https://github.com/jeremyevans/ruby/commit/c95e7e5329140f640b6497905485761f3336d967

Among other things, this fixes calling visibility methods (public?,
protected?, and private?) on them.  It also fixes #owner to show the
class the zsuper method entry is defined in, instead of the original
class it references.

For some backwards compatibility, adjust #parameters and #source_location,
to show the parameters and source location of the method originally
defined. Also have the parameters and source location still be shown
by #inspect.

Clarify documentation of {Method,UnboundMethod}#owner.

Add tests based on the description of https://bugs.ruby-lang.org/issues/18435
and based on https://github.com/ruby/ruby/pull/5356#issuecomment-1005298809

Fixes [Bug #18435] [Bug #18729]

Co-authored-by: Benoit Daloze <eregontp@gmail.com>

1 files changed, 54 insertions, 5 deletions

diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index 56e94493d9..5f689c3d4f 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -1056,20 +1056,28 @@ class TestMethod < Test::Unit::TestCase
     assert_equal(sm, im.clone.bind(o).super_method)
   end
 
-  def test_super_method_removed
+  def test_super_method_removed_public
     c1 = Class.new {private def foo; end}
     c2 = Class.new(c1) {public :foo}
     c3 = Class.new(c2) {def foo; end}
     c1.class_eval {undef foo}
     m = c3.instance_method(:foo)
     m = assert_nothing_raised(NameError, Feature9781) {break m.super_method}
-    assert_nil(m, Feature9781)
+    assert_equal c2, m.owner
+  end
+
+  def test_super_method_removed_regular
+    c1 = Class.new { def foo; end }
+    c2 = Class.new(c1) { def foo; end }
+    assert_equal c1.instance_method(:foo), c2.instance_method(:foo).super_method
+    c1.remove_method :foo
+    assert_equal nil, c2.instance_method(:foo).super_method
   end
 
   def test_prepended_public_zsuper
     mod = EnvUtil.labeled_module("Mod") {private def foo; :ok end}
-    mods = [mod]
     obj = Object.new.extend(mod)
+    mods = [obj.singleton_class]
     class << obj
       public :foo
     end
@@ -1079,7 +1087,7 @@ class TestMethod < Test::Unit::TestCase
     end
     m = obj.method(:foo)
     assert_equal(mods, mods.map {m.owner.tap {m = m.super_method}})
-    assert_nil(m)
+    assert_nil(m.super_method)
   end
 
   def test_super_method_with_prepended_module
@@ -1192,6 +1200,47 @@ class TestMethod < Test::Unit::TestCase
     assert_nil(super_method)
   end
 
+  # Bug 18435
+  def test_instance_methods_owner_consistency
+    a = Module.new { def method1; end }
+
+    b = Class.new do
+      include a
+      protected :method1
+    end
+
+    assert_equal [:method1], b.instance_methods(false)
+    assert_equal b, b.instance_method(:method1).owner
+  end
+
+  def test_zsuper_method_removed
+    a = EnvUtil.labeled_class('A') do
+      private
+      def foo(arg = nil)
+        1
+      end
+    end
+    line = __LINE__ - 4
+
+    b = EnvUtil.labeled_class('B', a) do
+      public :foo
+    end
+
+    unbound = b.instance_method(:foo)
+
+    assert_equal unbound, b.public_instance_method(:foo)
+    assert_equal "#<UnboundMethod: B(A)#foo(arg=...) #{__FILE__}:#{line}>", unbound.inspect
+    assert_equal [[:opt, :arg]], unbound.parameters
+
+    a.remove_method(:foo)
+
+    assert_equal [[:rest]], unbound.parameters
+    assert_equal "#<UnboundMethod: B#foo(*)>", unbound.inspect
+
+    obj = b.new
+    assert_raise_with_message(NoMethodError, /super: no superclass method `foo'/) { unbound.bind_call(obj) }
+  end
+
   def rest_parameter(*rest)
     rest
   end
@@ -1310,7 +1359,7 @@ class TestMethod < Test::Unit::TestCase
       ::Object.prepend(M2)
 
       m = Object.instance_method(:x)
-      assert_equal M, m.owner
+      assert_equal M2, m.owner
     end;
   end