Why is this legal?

[rikki cattermole via Digitalmars-d-learn]

On 29/03/2017 10:50 AM, abad wrote:
> This works:
>
> class Foo {
>     protected void bar() {
>         writeln("hello from foo");
>     }
> }
>
> void main() {
>     auto foo = new Foo;
>     foo.bar();
> }
>
> Is this on purpose and what's the rationale?

http://dlang.org/spec/attribute.html#visibility_attributes

"protected only applies inside classes (and templates as they can be 
mixed in) and means that a symbol can only be seen by members of the 
same module, or by a derived class. If accessing a protected instance 
member through a derived class member function, that member can only be 
accessed for the object instance which can be implicitly cast to the 
same type as ‘this’. protected module members are illegal."