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

[Atila Neves]

On Sunday, 29 July 2018 at 07:45:35 UTC, Walter Bright wrote:
> 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;
>
> -------

void main() {
     pragma(msg, __traits(allMembers, ns));
     foo;
     bar;
}

$ dmd foo.d
tuple("foo")
foo.d(15): Error: undefined identifier bar

That method doesn't compile.


> and another:
>
> -----
> extern (C++, ns) { int foo(); }
>
> struct S
> {
>   extern (C++, ns) { int bar(); }
> }
> ----

void main() {
     foo;
     bar;
}

I changed them to be only declarations, since the goal is to call 
existing C++ code, not to define it in a D file. `foo` works as 
expected, but `bar`...

foo.o:foo.d:function _Dmain: error: undefined reference to 
'S::ns::bar()'
collect2: error: ld returned 1 exit status

Neither method works.