Enable refinements at Object#respond_to?

[Feature #15327] [Fix GH-2020]

From: osyo-manga <manga.osyo@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65920 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -20,6 +20,8 @@ sufficient information, see the ChangeLog file or Redmine
 
 * refinements takes place at Kernel#public_send.  [Feature #15326]
 
+* refinements takes place at Kernel#respond_to?.  [Feature #15327]
+
 * +else+ without +rescue+ now causes a syntax error.  [EXPERIMENTAL]
 
 * constant names may start with a non-ASCII capital letter. [Feature #13770]

spec/ruby/core/module/refine_spec.rb

@@ -524,6 +524,7 @@ describe "Module#refine" do
       }.should raise_error(NameError, /undefined method `foo'/)
     end
 
+    ruby_version_is "" ... "2.6" do
       it "is not honored by Kernel#respond_to?" do
         klass = Class.new
         refinement = Module.new do
@@ -542,6 +543,26 @@ describe "Module#refine" do
       end
     end
 
+    ruby_version_is "2.6" do
+      it "is honored by Kernel#respond_to?" do
+        klass = Class.new
+        refinement = Module.new do
+          refine klass do
+            def foo; end
+          end
+        end
+
+        result = nil
+        Module.new do
+          using refinement
+          result = klass.new.respond_to?(:foo)
+        end
+
+        result.should == true
+      end
+    end
+  end
+
   context "when super is called in a refinement" do
     it "looks in the included to refinery module" do
       refinement = Module.new do

test/ruby/test_refinement.rb

@@ -326,9 +326,9 @@ class TestRefinement < Test::Unit::TestCase
     end
   end
 
-  def test_respond_to_should_not_use_refinements
+  def test_respond_to_should_use_refinements
     assert_equal(false, 1.respond_to?(:foo))
-    assert_equal(false, eval_using(IntegerFooExt, "1.respond_to?(:foo)"))
+    assert_equal(true, eval_using(IntegerFooExt, "1.respond_to?(:foo)"))
   end
 
   module StringCmpExt

vm_method.c

@@ -1089,7 +1089,14 @@ rb_export_method(VALUE klass, ID name, rb_method_visibility_t visi)
 int
 rb_method_boundp(VALUE klass, ID id, int ex)
 {
-    const rb_method_entry_t *me = rb_method_entry_without_refinements(klass, id, NULL);
+    const rb_method_entry_t *me;
+
+    if (ex & BOUND_RESPONDS) {
+        me = method_entry_resolve_refinement(klass, id, TRUE, NULL);
+    }
+    else {
+        me = rb_method_entry_without_refinements(klass, id, NULL);
+    }
 
     if (me != 0) {
 	if ((ex & ~BOUND_RESPONDS) &&