Warn when redefining __id__ as well as object_id

[Feature #20912]

Author: jhawthorn

defs/id.def

@@ -8,6 +8,7 @@ firstline, predefined = __LINE__+1, %[\
   inspect
   intern
   object_id
+  __id__
   const_added
   const_missing
   method_missing                                        MethodMissing

spec/ruby/core/basicobject/equal_spec.rb

@@ -11,8 +11,10 @@
   it "is unaffected by overriding __id__" do
     o1 = mock("object")
     o2 = mock("object")
-    def o1.__id__; 10; end
-    def o2.__id__; 10; end
+    suppress_warning {
+      def o1.__id__; 10; end
+      def o2.__id__; 10; end
+    }
     o1.equal?(o2).should be_false
   end
 

test/ruby/test_module.rb

@@ -1488,7 +1488,7 @@ def test_undef
       class << o; self; end.instance_eval { undef_method(:foo) }
     end
 
-    %w(object_id __send__ initialize).each do |n|
+    %w(object_id __id__ __send__ initialize).each do |n|
       assert_in_out_err([], <<-INPUT, [], %r"warning: undefining '#{n}' may cause serious problems$")
         $VERBOSE = false
         Class.new.instance_eval { undef_method(:#{n}) }

test/ruby/test_object.rb

@@ -480,7 +480,7 @@ def o.foo; 2; end
   end
 
   def test_redefine_method_which_may_case_serious_problem
-    %w(object_id __send__).each do |m|
+    %w(object_id __id__ __send__).each do |m|
       assert_in_out_err([], <<-INPUT, [], %r"warning: redefining '#{m}' may cause serious problems$")
         $VERBOSE = false
         def (Object.new).#{m}; end
@@ -542,7 +542,7 @@ def meth1; "meth" end
     bug2202 = '[ruby-core:26074]'
     assert_raise(NoMethodError, bug2202) {o2.meth2}
 
-    %w(object_id __send__ initialize).each do |m|
+    %w(object_id __id__ __send__ initialize).each do |m|
       assert_in_out_err([], <<-INPUT, %w(:ok), %r"warning: removing '#{m}' may cause serious problems$")
         $VERBOSE = false
         begin

vm_method.c

@@ -1072,7 +1072,7 @@ rb_method_entry_make(VALUE klass, ID mid, VALUE defined_class, rb_method_visibil
         }
     }
     /* check mid */
-    if (mid == object_id || mid == id__send__) {
+    if (mid == object_id || mid == id__id__ || mid == id__send__) {
         if (type != VM_METHOD_TYPE_CFUNC && search_method(klass, mid, 0)) {
             rb_warn("redefining '%s' may cause serious problems", rb_id2name(mid));
         }
@@ -1681,7 +1681,7 @@ remove_method(VALUE klass, ID mid)
 
     rb_class_modify_check(klass);
     klass = RCLASS_ORIGIN(klass);
-    if (mid == object_id || mid == id__send__ || mid == idInitialize) {
+    if (mid == object_id || mid == id__id__ || mid == id__send__ || mid == idInitialize) {
         rb_warn("removing '%s' may cause serious problems", rb_id2name(mid));
     }
 
@@ -1911,7 +1911,7 @@ rb_undef(VALUE klass, ID id)
         rb_raise(rb_eTypeError, "no class to undef method");
     }
     rb_class_modify_check(klass);
-    if (id == object_id || id == id__send__ || id == idInitialize) {
+    if (id == object_id || id == id__id__ || id == id__send__ || id == idInitialize) {
         rb_warn("undefining '%s' may cause serious problems", rb_id2name(id));
     }