D-dll support: testers needed round 2

[Rainer Schuetze]

On 21/03/2018 07:46, evilrat wrote:
> On Friday, 9 February 2018 at 20:34:33 UTC, Benjamin Thaut wrote:
>> My work on dll support for D continues. There is another iteration I 
>> need help testing with.
>>
>> Getting started tutorial: 
>> http://stuff.benjamin-thaut.de/D/getting_started.html
>>
>> A binary distribution is provided, see the tutorial for details.
> 
> Played a bit with your binaries, here are some issues.
> 
> Importing non-compiled modules works ok.
> However when doing manual library loading(both WinAPI LoadLibrary and 
> Runtime.loadLibrary) things is the same as in vanilla DMD/LDC - casting 
> not working.
> 
> Classes(incl. abstract) works in a hacky way (first cast to void* - then 
> to actual class), again same as plain DMD, no changes here.
> 
> Interfaces doesn't work at all, doing the hack above on 
> interface-derived object messes up vtbl/offsets, resulting in wrong 
> function called.
> 
> -import switch seems to do the trick, but how to deal with dynamic loading?
> 

I guess you want to cast to a class that is only defined in the 
dynamically loaded DLL? The problem is that casting needs a reference to 
the class info of the target class which only exists in the referenced 
DLL, which needs static DLL linkage.

One suggestion would be to export a common class/interface definition 
from a DLL that is referenced by both the dynamic DLL and the loading 
executable.