Fix for overriding protected with protected

- A better solution may be explored

lib/member_builder.js

@@ -145,6 +145,9 @@ exports.buildMethod = function(
         // to ensure privileged calls will work properly
         dest[ name ] = overrideMethod( value, null, instCallback, cid );
     }
+
+    // store keywords for later reference (needed for pre-ES5 fallback)
+    dest[ name ].___$$keywords$$ = keywords;
 };
 
 

lib/propobj.js

@@ -71,7 +71,11 @@ exports.setup = function( dest, properties, methods )
     // public. The reason for this is because the property object is laid /atop/
     // of the public members, meaning that a parent's protected members will
     // take precedence over a subtype's overriding /public/ members. Uh oh.
-    doSetup( dest, properties[ 'protected' ], methods[ 'protected' ], true );
+    doSetup( dest,
+        properties[ 'protected' ],
+        methods[ 'protected' ],
+        'public'
+    );
 
     // then add the private parts
     doSetup( obj, properties[ 'private' ], methods[ 'private' ] );
@@ -90,11 +94,10 @@ exports.setup = function( dest, properties, methods )
  *
  * @return  {undefined}
  */
-function doSetup( dest, properties, methods, unless_exists )
+function doSetup( dest, properties, methods, unless_keyword )
 {
-    unless_exists = !!unless_exists;
-
-    var hasOwn = Array.prototype.hasOwnProperty;
+    var hasOwn = Array.prototype.hasOwnProperty,
+        pre    = null;
 
     // copy over the methods
     if ( methods !== undefined )
@@ -103,13 +106,24 @@ function doSetup( dest, properties, methods, unless_exists )
         {
             if ( hasOwn.call( methods, method_name ) )
             {
+                pre = dest[ method_name ];
+
                 // If requested, do not copy the method over if it already
                 // exists in the destination object. Don't use hasOwn here;
                 // unnecessary overhead and we want to traverse any prototype
                 // chains. We do not check the public object directly, for
                 // example, because we need a solution that will work if a proxy
                 // is unsupported by the engine.
-                if ( !unless_exists || ( dest[ method_name ] === undefined ) )
+                //
+                // Also note that we need to allow overriding if it exists in
+                // the protected object (we can override protected with
+                // protected). This is the *last* check to ensure a performance
+                // hit is incured *only* if we're overriding protected with
+                // protected.
+                if ( !unless_keyword
+                    || ( pre === undefined )
+                    || !( pre.___$$keywords$$[ unless_keyword ] )
+                )
                 {
                     dest[ method_name ] = methods[ method_name ];
                 }

test/test-class-visibility.js

@@ -725,3 +725,41 @@ var common    = require( './common' ),
     );
 } )();
 
+
+/**
+ * There was a bug introduced when we prevented protected members from
+ * overriding public (since in the prototype chain, protected members are laid
+ * atop public, and this cannot change). This bug would disallow protected
+ * members from being overridden by other protected members.
+ *
+ * This test is both a proof and a regression test.
+ */
+( function testCanProperlyOverrideProtectedWithProtected()
+{
+    var val    = 'foobar',
+        result = Class(
+        {
+            'protected foo': function() {},
+        } ).extend(
+        {
+            // provide concrete implementation
+            'protected foo': function()
+            {
+                return val;
+            },
+
+            'public doFoo': function()
+            {
+                return this.foo();
+            },
+        } )().doFoo();
+    ;
+
+    // if everything worked as expected, the value of 'val' will have been
+    // returned and stored in 'result'
+    assert.equal( result, val,
+        "Protected methods can properly be overriden by another protected " +
+            "method"
+    );
+} )();
+