[SOLVED] Windows DLL _stdcall without name mangeling

Andy314

Hello !
Sorry for my simple newbie in Qt question but I found no easy solution in the net.
I want create simple windows-dll and I must use _stdcall. How can I give the exported functions a custom (simple "extern C") name.
Has Qt (gmake) a mechanism to obtain and forward it to gcc resp. the linker.
Thanks

Chris Kawa

Hi, welcome to devnet.

This question is not really related to Qt (which is just another c++ library). The way you do this is specific to your compiler.
If you want unmangled names then are you sure you want __stdcall and not __cdecl?

If you want to undecorate the __stdcall functions created with MSVC you can either create a .def file for your library or use the /export linker switch.

The way to pass custom params to linker when you're using qmake is by adding it to the .pro file with the QMAKE_LFLAGS i.e.
QMAKE_LFLAGS += your_params_here.

Andy314

Yes it has indeed nothing to do with Qt and its a compiler specific.
Because both Qt and GCC is very new for me I asked the question.

I found a simple solution for MinGW
QMAKE_LFLAGS += -Wl,--add-stdcall-alias
which integrated the simple names additional.

alex_malyu

What is wrong in using extern C in declaration?
Then you can check for specific compiler.
Something like below:

#ifdef __cplusplus
extern "C" {
#endif

#ifndef __STDCALL
#if defined(_WIN32) && defined(_MSC_VER)
#define __STDCALL __stdcall
#else
#define __STDCALL
#endif
#endif

int __STDCALL myFunction1();
void __STDCALL myFunction2();

#ifdef __cplusplus
} // end of extern "C"
#endif

Chris Kawa

Cool. Thanks for sharing.

Chris Kawa

@alex_malyu __stdcall, as opposed to __cdecl decorates even functions marked as extern "C". You need additional linker support to undecorate them or a .def file.

alex_malyu

Above posted code works for on WIndows up to VS2013 with Microsoft and Intel compilers + on Linux with Intel compiler and GCC.
I am pretty sure about naming, cause our code involves Fortran which would not be able to call any C routine otherwise.

Chris Kawa

Yes, but notice that above code uses __cdecl for anything but MSVC.

alex_malyu

You are right, I forgot we never used GCC on Windows and always __cdecl f on other platforms.