final invariant request = disallow meaningless attributes

[Ary Manzana]

I totally agree with this.

If one of the purposes of the new modifiers are to provide better 
documenation from within the language itself, then if the compiler 
doesn't warn you if you write

const invariant int x = 3;

then it's counterproductive. Against the meaning of "provide better 
documentation".

Deewiant escribió:
> With the new constants, people, including many who have used D for a long time,
> are more confused than ever before about what certain combinations of attributes
> mean. The compiler still accepts interesting code like:
> 
> export public public private protected package int apple;
> 
> I think this has become a real issue now that the difference, or lack thereof,
> between the following isn't obvious:
> 
> const           int x = 3;
> invariant       int x = 3;
> const invariant int x = 3;