Hi Brian,
The problem is that hs_free_fun_ptr is defined in a static library
(the Haskell RTS) while you have declared it with
__declspec(dllimport). In this case the compiler is tring tp optimize
the call and it is using __imp__hs_free_fun_ptr instead of
hs_free_fun_ptr. You have to remove the dllimport pragma and to link
your program with the Haskell RTS library. Unfortunatelly the the
static library format is different for VC++ and GCC and I expect that
you may have problems if you try to statically link gcc code with VC++
code.
Cheers,
Krasimir
2006/3/25, Brian Hulley
Hi - I have the following declaration and code in part of a DLL I'm writing:
extern "C" { typedef void (*HsFunPtr)(); extern __declspec(dllimport) void hs_free_fun_ptr(HsFunPtr fp); }
enum ECallback { ECallback_Render, ECallback_COUNT};
HsFunPtr callback[ECallback_COUNT];
void SetCallback(ECallback c, HsFunPtr fp){ if (callback[c]){ hs_free_fun_ptr(callback[c]); } callback[c] = fp; }
However when I try to build the DLL, I get the following error from Visual Studio:
Duma.obj : error LNK2019: unresolved external symbol __imp__hs_free_fun_ptr
So the problem is that the VS is adding __imp__ onto the function name even though I've specified it as extern "C" and is moreover just ignoring the dllimport directive and complaining that it can't find the function.
I've also tried deleting the "extern" before the "__declspec" but this doesn't make any difference. Also, I've tried putting hs_free_fun_ptr into the IMPORTS section of the def file but this doesn't make any difference either (I don't even think def files have an IMPORTS section so it's probably just being ignored).
I've got a horrible feeling that VS will need a .lib file for ghc to allow it to link against hs_free_fun_ptr but I don't have a clue how to generate one...
Does anyone know how I can get everything to link?
Thanks, Brian.
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