What is the wrong with my C++ interfacing

[drug]

On 3/16/20 10:11 AM, Ferhat Kurtulmuş wrote:
> On Sunday, 15 March 2020 at 22:25:27 UTC, Arine wrote:
>> On Sunday, 15 March 2020 at 21:27:32 UTC, Ferhat Kurtulmuş
> 
>> extern(C++, cv){
>> extern(C++, class) struct Size_(_Tp){
>>     @disable this();
>>     ~this() { }
>>
>>     final _Tp area() const;
>>     final double aspectRatio() const;
>>     final bool empty() const;
>>
>>     _Tp width; //!< the width
>>     _Tp height; //!< the height
>> }
>> }
>>
>> extern(C++){
>>     cv.Size_!int* createSizeIntWH(int w, int h);
>> }
>>
>> void main()
>> {
>>     Size_!int* sz = createSizeIntWH(200, 100);
>>     writeln(sz.width);
>> }
> 
> This worked for me too. But member functions are still causing linker 
> error. It seems like docs (https://dlang.org/spec/cpp_interface.html) do 
> not cover those situations. Is there any other sources to read for it. 
> Maybe you make a pull request to docs covering C++ interfacing tips in 
> detail.

Not tested:

  extern(C++, class) struct Size_(_Tp){
      @disable this();
      ~this() { }
extern(C++): // <- IIRC linkage should be set for members separately 
from aggregate
      final _Tp area() const;
      final double aspectRatio() const;
      final bool empty() const;

      _Tp width; //!< the width
      _Tp height; //!< the height
  }