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

[Walter Bright]

On 7/28/2018 9:23 PM, Manu wrote:
> Don't troll me on this one, this is a very sensitive topic!
> I could have a legit mental breakdown ;)


Here's another method:

------
extern (C++, ns) { int foo() { return 1; } }

mixin template X()
{
   extern (C++, ns) { int bar() { return 2; } }
}

mixin X!() x;

-------

and another:

-----
extern (C++, ns) { int foo() { return 1; } }

struct S
{
   extern (C++, ns) { int bar() { return 2; } }
}
----