Resolve C superclass variables assigned from rb_const_get

lib/rdoc/parser/c.rb

@@ -862,7 +862,7 @@ def handle_attr(var_name, attr_name, read, write)
       # named +class_name+ in +parent+ which was assigned to the C +var_name+.
 
       def handle_class_module(var_name, type, class_name, parent, in_module)
-        parent_name = @known_classes[parent] || parent
+        parent_name = @known_classes[parent] || const_get_name(parent) || parent
 
         if in_module
           enclosure = @classes[in_module] || @store.find_c_enclosure(in_module)
@@ -917,6 +917,35 @@ def handle_class_module(var_name, type, class_name, parent, in_module)
         @store.add_c_enclosure var_name, cm
       end
 
+      ##
+      # Returns the name of the class or module the C variable +var_name+ was
+      # assigned from <tt>rb_const_get(under, rb_intern("Name"))</tt>, or +nil+
+      # if there is no such assignment, +under+ is unknown, or +var_name+ is
+      # assigned different constants in different places.
+      #
+      #: (String?) -> String?
+      def const_get_name(var_name)
+        return unless var_name
+
+        names = @content.scan(%r%
+          \b#{Regexp.escape var_name}\s*=
+          \s*rb_const_get(?:_at)?\s*\(
+            \s*(\w+)\s*,
+            \s*rb_intern(?:_const)?\s*\(\s*"(\w+)"\s*\)
+          \s*\)
+        %x).uniq
+
+        return unless names.length == 1
+
+        under, name = names.first
+        under_name = @known_classes[under]
+
+        return unless under_name
+        return name if under_name == 'Object'
+
+        "#{under_name}::#{name}"
+      end
+
       ##
       # Adds constants.  By providing some_value: at the start of the comment you
       # can override the C value of the comment to give a friendly definition.

lib/rdoc/store.rb

@@ -307,7 +307,8 @@ def cleanup_stale_contributions
 
     def resolve_c_superclasses
       @classes_hash.each_value do |klass|
-        if klass.superclass.is_a?(String) && (candidate = find_c_enclosure(klass.superclass))
+        if klass.superclass.is_a?(String) && (candidate = find_c_enclosure(klass.superclass)) &&
+           !candidate.equal?(klass)
           klass.superclass = candidate
         end
       end

test/rdoc/parser/c_test.rb

@@ -497,6 +497,47 @@ def test_do_classes_class_under_rb_path2class
     assert_equal 'this is Kernel::Foo < A::B', klass.comment.text
   end
 
+  def test_do_classes_class_under_rb_const_get
+    content = <<~C
+      VALUE mExample = rb_define_module("Example");
+      VALUE cSocket = rb_const_get(rb_cObject, rb_intern("Socket"));
+      cSocket = rb_define_class_under(mExample, "Socket", cSocket);
+    C
+
+    klass = util_get_class content, 'cSocket'
+
+    assert_equal 'Example::Socket', klass.full_name
+    assert_equal 'Socket', klass.superclass
+  end
+
+  def test_do_classes_class_rb_const_get_under_module
+    content = <<~C
+      VALUE mNet = rb_define_module("Net");
+      VALUE cProtocol = rb_const_get(mNet, rb_intern("Protocol"));
+      VALUE cFoo = rb_define_class("Foo", cProtocol);
+    C
+
+    klass = util_get_class content, 'cFoo'
+
+    assert_equal 'Foo', klass.full_name
+    assert_equal 'Net::Protocol', klass.superclass
+  end
+
+  def test_do_classes_class_rb_const_get_reassigned
+    content = <<~C
+      VALUE mA = rb_define_module("A");
+      VALUE klass = rb_const_get(rb_cObject, rb_intern("IO"));
+      VALUE cX = rb_define_class_under(mA, "X", klass);
+      klass = rb_const_get(rb_cObject, rb_intern("String"));
+      VALUE cY = rb_define_class_under(mA, "Y", klass);
+    C
+
+    klass = util_get_class content, 'cY'
+
+    assert_equal 'A::Y', klass.full_name
+    assert_equal 'klass', klass.superclass
+  end
+
   def test_do_classes_singleton
     content = <<~C
       VALUE cFoo = rb_define_class("Foo", rb_cObject);

test/rdoc/rdoc_store_test.rb

@@ -299,6 +299,17 @@ def test_resolve_c_superclasses
     assert_equal(parent, @s.classes_hash['Child'].superclass)
   end
 
+  def test_resolve_c_superclasses_self
+    c_file = @s.add_file 'ext.c'
+    klass = c_file.add_class RDoc::NormalClass, 'Socket', 'cSocket'
+
+    @s.add_c_enclosure('cSocket', klass)
+
+    @s.resolve_c_superclasses
+
+    assert_equal 'cSocket', @s.classes_hash['Socket'].superclass
+  end
+
   def test_find_class_named
     assert_equal @c1, @store.find_class_named('C1')