Why can't we use strings in C++ methods?

[Dadoum]

On Saturday, 4 November 2023 at 10:08:20 UTC, Imperatorn wrote:
> On Saturday, 4 November 2023 at 03:00:49 UTC, Dadoum wrote:
>> I was wondering why C++ linkage forbids strings as arguments 
>> while we can with the C one.
>>
>> With C linkage, it's translated to a template that's defined 
>> in the automatically generated header, but it just doesn't 
>> compile in C++.
>
> Can you provide an example of exactly what you want to do?

```d
extern (C) void hello(string arg) {
     import std.stdio;
     writeln(arg);
}
```

Compiles fine with dmd, ldc2 and gdc.


```d
extern (C++) void hello(string arg) {
     import std.stdio;
     writeln(arg);
}
```

Doesn't compile.

DMD: `Internal Compiler Error: type `string` cannot be mapped to 
C++`
GDC and LDC2: `function 'example.hello' cannot have parameter of 
type 'string' because its linkage is 'extern(C++)'`

And I am wondering why the type can be mapped to a template in C 
but not in C++. (you can see the template used when you compile 
with `-H --HCf=./header.h`