__traits(parent) bug?

[Imperatorn]

On Saturday, 24 October 2020 at 17:46:55 UTC, Stefan Koch wrote:
> On Saturday, 24 October 2020 at 15:45:03 UTC, Paul Backus wrote:
>
>>
>> I'm not sure that this can really be called a bug, per se--the 
>> language spec is vague enough to allow either 
>> interpretation--but I'd be very surprised if this behavior was 
>> intentional.
>
> The rewrite to get the eponymous member is applied to the 
> parent :)
> Not intentional but a consequence of the rewrite rule.

Where is this behavior documented?