Is there any good reason why C++ namespaces are "closed" in D?

[Laeeth Isharc]

On Saturday, 28 July 2018 at 01:03:10 UTC, Walter Bright wrote:
> On 7/27/2018 4:15 PM, Laeeth Isharc wrote:
>> Can you think of a pragmatic solution to Atila's problem?
>
> One way is for the C++ => D translator to gather all the 
> members of a namespace before trying to emit them. Since D does 
> not impose an order on declarations (unlike C++) it is not 
> constrained to follow the same order.

So a new post preprocessor stage that parses the produced D code 
and regroups to group the declarations in the same namespace 
together ?  Using DMD as a library or libdparse or something?