Re: Exported function mangaled name

From:

Manish Agarwal <manish.k.agarwal@gmail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 27 Feb 2009 04:58:30 -0800 (PST)

Message-ID:

<7ea1f479-79b4-48bf-8c52-1ccd99ceafbd@e36g2000prg.googlegroups.com>

On Feb 10, 12:25 pm, "Manish Agarwal" <manishkris...@hotmail.com>
wrote:

Thank you Joseph, I know all these (a to c) but I used the example just t=

focus on the issue that I am facing. I am working on a huge product
(hundreds of files) with many DLLs and supporting this for Windows 32 bit
and 64 bit. I know the work around i.e. using def file etc. but my questi=

is pretty much simple:

Why there is a difference in exported names for same source code compiled
for Win32 and Win64, while theoretically there should be no. Is it a VS20=

bug or some undocumented change ?

Regards,
Manish K. Agarwal

"Joseph M. Newcomer" <newco...@flounder.com> wrote in messagenews:2h4po49=

rck4ebim51dbbsigkosko04ke79@4ax.com...

See below...
On Fri, 6 Feb 2009 17:07:40 +0530, "Manish Agarwal"
<manishkris...@hotmail.com> wrote:

Hi,

I am exporting following function:

TestFunc.h

extern "C" {
__declspec(dllexport)int__stdcallTestFunc(void);
}

TestFunc.cpp

****
Put
extern "C"
before this declaration. You have otherwise defined a function unrel=

ated

to the header
specification.

extern "C"__declspec(dllexport)int__stdcallTestFunc(void);

Note several things:
(a) you cannot declare it as__declspec(dllexport) in the header file if
the clients use
that header file; it must be declared as__declspec(dllimport)
(b) You don't need to specify (void), because () works just as well and
means the same
thing
(c) You have to declare the function the same way in your .cpp file as =

your .h file

That is, the usual technique is to do, for your .h file

#pragma once
#ifdef _SOME_GUID_BASED_SYMBOL
#define LIBSPEC__declspec(dllexport)
#else
#define LIBSPEC__declspec(dllimport)
#endif
extern "C" {
LIBSPECint__stdcallTestFuc();
}
#undef LIBSPEC

and in building your DLL, you write in the .cpp file:

#include "stdafx.h"
#define _SOME_GUID_BASED_SYMBOL
#include "TestFunc.h"

extern "C"__declspec(dllexport)int__stdcallTestFunc()
  {
   ... function body
  }

See my essay on The Ultimate DLL Header File on my MVP Tips site.
****

__declspec(dllexport)int__stdcallTestFunc(void)
{
return 42;
}

When I compile the above with VS2005 for Windows 32 bit, the decorated
function name is "_TestFunc@0"

and when I compile it with VS2005 for Windows 64 bit, the decorated
function
name is "TestFunc"

Why there is a difference, what I am missing here. Is it documented som=

where ? Even I created a simple DLL using VS wizard and copied all proj=

ect

setting for Win64 from Win32 settings. Nothing I changed manually in
project
setting.

Regards,
Manish K. Agarwal

PS: Sorry I have to post it again because on other group, I was uanble =

get the exact answer.

Joseph M. Newcomer [MVP]
email: newco...@flounder.com
Web:http://www.flounder.com
MVP Tips:http://www.flounder.com/mvp_tips.htm- Hide quoted text -

- Show quoted text -

I think the correct reason to this is-

http://msdn.microsoft.com/en-us/library/ms235286.aspx

This says "Given the expanded register set, x64 just uses the
__fastcall calling convention"