flamencofantasy, thanx for that! Where do we vote here? =)

Moving further discussion to here: http://forum.dlang.org/thread/xpliectmvwrwthamquke@forum.dlang.org

"Yuriy"  wrote in message news:uflaemdlxvavfmvkbudq@forum.dlang.org... 

> Hello, is there a way of reducing size of an empty class to just vtbl? I tried to declare it as extern(C++) which works, but has a nasty side effect of limited mangling.

What exactly is the mangling problem with extern(C++) classes?

On Tuesday, 13 May 2014 at 17:09:01 UTC, Daniel Murphy wrote:
> What exactly is the mangling problem with extern(C++) classes?
Can't use D arrays (and strings) as function argument types.
Can't use D array types as template arguments.

extern (C++) MyClass(T)
{

}

MyClass!string a; // Mangling error

On Tuesday, 13 May 2014 at 17:41:42 UTC, Yuriy wrote:
> On Tuesday, 13 May 2014 at 17:09:01 UTC, Daniel Murphy wrote:
>> What exactly is the mangling problem with extern(C++) classes?
> Can't use D arrays (and strings) as function argument types.
> Can't use D array types as template arguments.
>
> extern (C++) MyClass(T)
> {
>
> }
>
> MyClass!string a; // Mangling error

I'm not getting any errors with the development head.  What os/compiler version?

On Wednesday, 14 May 2014 at 08:47:38 UTC, Daniel Murphy wrote:
> I'm not getting any errors with the development head.  What os/compiler version?
Hm, now that's strange. Building with latest public version seems to work. However, development head is doing the following:
$ ./test.d
Error: ICE: Unsupported type string

Assertion failed: (0), function visit, file cppmangle.c, line 440.

I'm using MacOS 10.9.2.

The test.d is: http://dpaste.dzfl.pl/2aa4ca932be1

On Tuesday, 13 May 2014 at 17:41:42 UTC, Yuriy wrote:
> On Tuesday, 13 May 2014 at 17:09:01 UTC, Daniel Murphy wrote:
>> What exactly is the mangling problem with extern(C++) classes?
> Can't use D arrays (and strings) as function argument types.
> Can't use D array types as template arguments.
>
> extern (C++) MyClass(T)
> {
>
> }
>
> MyClass!string a; // Mangling error

that should not compile at all. Perhaps you thought extern(C++) interface MyClass(T) ?

On Wednesday, 14 May 2014 at 10:21:00 UTC, Dejan Lekic wrote:
> that should not compile at all. Perhaps you thought extern(C++) interface MyClass(T) ?
Ok, how about this one?
http://dpaste.dzfl.pl/04655ff6ddfd
It doesn't compile either.

On 05/14/2014 04:15 AM, Yuriy wrote:
> On Wednesday, 14 May 2014 at 10:21:00 UTC, Dejan Lekic wrote:
>> that should not compile at all. Perhaps you thought extern(C++)
>> interface MyClass(T) ?
> Ok, how about this one?
> http://dpaste.dzfl.pl/04655ff6ddfd
> It doesn't compile either.

extern(C++) interface I
{
    string hi();
}

extern(C++) class A(T) : I
{
    override string hi()
    {
        return "asdf";
    }
}

void main()
{
    A!string a;
}

/d208/f532.d(9): Error: class f532.A!(string).A cannot create C++ classes /d208/f532.d(19): Error: template instance f532.A!(string) error instantiating

Yeah, that is a documented limitation when using C++ code. C++ templates cannot be used in D. "C++ Templates" here:

  http://dlang.org/cpp_interface.html

Ali

Ali, i think that paragraph is talking about another case, which is not my case. I'm not trying to use C++ templates, nor to export a D template to C++. Besides, i guess that D template, implementing a C++ interface is perfectly valid, regardless it's template arguments, since it is instantiated on the D side anyway. Also i guess that such types as D arrays should not support mangling when used as function arguments/rettype, they are not compatible with C++ anyway, but when they become part of a class template, they should mangle somehow. IMHO.

On Wednesday, 14 May 2014 at 14:08:52 UTC, Ali Çehreli wrote:
> Yeah, that is a documented limitation when using C++ code. C++ templates cannot be used in D. "C++ Templates" here:
>
>   http://dlang.org/cpp_interface.html
>
> Ali