• Nicholas Wilson (19/19) Apr 24 2019 How do you pass a delegate to a c++ function to be called by it?
• Jacob Carlborg (4/28) Apr 24 2019 You probably need to include `extern(C++)` in the cast, if that's possib...
• Alex (4/25) Apr 25 2019 It's clear that your delegate is not extern C++

Nicholas Wilson <iamthewilsonator hotmail.com> writes:

How do you pass a delegate to a c++ function to be called by it?

The function to pass the delegate to is:

extern (C++) int
fakeEntrypoint(
     extern(C++) void function(void* /*delegate's context*/) func,
     void* /*delegate's context*/ arg);


What I want is:

int entrypoint(scope void delegate() func)
{
     return fakeEntrypoint(
                 // for some reason func.funcptr is void function()
                 cast(void function(void*))func.funcptr,
                 func.ptr);
}

but that fails with

cannot pass argument cast(void function(void*))func.funcptr of 
type
void function(void*) to parameter extern (C++) void 
function(void*) func

Jacob Carlborg <doob me.com> writes:

On 2019-04-24 18:20, Nicholas Wilson wrote:
 How do you pass a delegate to a c++ function to be called by it?
 
 The function to pass the delegate to is:
 
 extern (C++) int
 fakeEntrypoint(
      extern(C++) void function(void* /*delegate's context*/) func,
      void* /*delegate's context*/ arg);
 
 
 What I want is:
 
 int entrypoint(scope void delegate() func)
 {
      return fakeEntrypoint(
                  // for some reason func.funcptr is void
function()
                  cast(void function(void*))func.funcptr,
                  func.ptr);
 }
 
 but that fails with
 
 cannot pass argument cast(void function(void*))func.funcptr of type
 void function(void*) to parameter extern (C++) void function(void*) func

You probably need to include `extern(C++)` in the cast, if that's possible.

-- 
/Jacob Carlborg

Alex <AJ gmail.com> writes:

On Wednesday, 24 April 2019 at 16:20:17 UTC, Nicholas Wilson 
wrote:
 How do you pass a delegate to a c++ function to be called by it?

 The function to pass the delegate to is:

 extern (C++) int
 fakeEntrypoint(
     extern(C++) void function(void* /*delegate's context*/) 
 func,
     void* /*delegate's context*/ arg);


 What I want is:

 int entrypoint(scope void delegate() func)
 {
     return fakeEntrypoint(
                 // for some reason func.funcptr is void 
 function()
                 cast(void function(void*))func.funcptr,
                 func.ptr);
 }

 but that fails with

 cannot pass argument cast(void function(void*))func.funcptr of 
 type
 void function(void*) to parameter extern (C++) void 
 function(void*) func

It's clear that your delegate is not extern C++


int entrypoint(scope extern(C++) void delegate() func)