since when was this valid syntax?

[Timon Gehr]

On 09/08/2012 04:11 PM, Ellery Newcomer wrote:
> alias enum int e;

It is valid according to the grammar and DMD ignores meaningless attributes.

scope shared @disable @trusted package final override deprecated extern 
__gshared synchronized pure nothrow ref static abstract immutable alias 
auto final override deprecated extern __gshared synchronized enum pure 
nothrow ref static abstract @safe @disable scope int e;