variable.c: top-level constant look-up

* variable.c (rb_const_search): [EXPERIMENTAL] remove top-level
  constant look-up.  [Feature #11547]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57244 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -14,6 +14,8 @@ with all sufficient information, see the ChangeLog file or Redmine
 
 === Language changes
 
+* Top-level constant look-up is removed.  [Feature #11547]
+
 === Core classes updates (outstanding ones only)
 
 === Stdlib updates (outstanding ones only)

variable.c

@@ -2273,8 +2273,12 @@ rb_const_search(VALUE klass, ID id, int exclude, int recurse, int visibility)
 		continue;
 	    }
 	    if (exclude && tmp == rb_cObject && klass != rb_cObject) {
+#if 0
 		rb_warn("toplevel constant %"PRIsVALUE" referenced by %"PRIsVALUE"::%"PRIsVALUE"",
 			QUOTE_ID(id), rb_class_name(klass), QUOTE_ID(id));
+#else
+		return Qundef;
+#endif
 	    }
 	    return value;
 	}