Re: [Dev-C++] Couldn`t link MinGW DLL to MSVC program

It is possible to create DLL files exporting variables and functions -
using "C" naming convention and mix between gcc and M$. However, you can't
export/import classes or other C++ symbols (and often not structs either),
since the C++ mangling - and the internal memory layout - is different
between the compilers.

Google on ABI (Application Binary Interface) and you will get more
information about the problem.

/Per W

On Sun, 27 Mar 2005, Dmitry Sidorov wrote:

> Hello dev-cpp-users.
>
> I have the following source files to build DLL with Dev-Cpp
>
>
> // dll.h
> #ifndef _DLL_H_
> #define _DLL_H_
>
> #if BUILDING_DLL
> # define DLLIMPORT __declspec (dllexport)
> #else /* Not BUILDING_DLL */
> # define DLLIMPORT __declspec (dllimport)
> #endif /* Not BUILDING_DLL */
>
> class DLLIMPORT MyClass
> {
>   public:
>     MyClass();
>     virtual ~MyClass(void);
> };
> #endif /* _DLL_H_ */
>
>
> // dllmain.cpp
> #include "dll.h"
> #include <windows.h>
>
> MyClass::MyClass()
> {
>     MessageBox( NULL, "MyClass construccted!!!", "test", 0 );
> }
> MyClass::~MyClass()
> {
> }
> BOOL APIENTRY DllMain (HINSTANCE hInst     /* Library instance handle. */ ,
>                        DWORD reason        /* Reason this function is being called. */ ,
>                        LPVOID reserved     /* Not used. */ )
> {
>     switch (reason)
>     {
>       case DLL_PROCESS_ATTACH:
>         break;
>
>       case DLL_PROCESS_DETACH:
>         break;
>
>       case DLL_THREAD_ATTACH:
>         break;
>
>       case DLL_THREAD_DETACH:
>         break;
>     }
>
>     /* Returns TRUE on success, FALSE on failure */
>     return TRUE;
> }
>
> This is standard DLL project of Dev-Cpp with MessageBox function in
> MyClass constructor
>
> I build DLL with Dev-Cpp and then build .LIB file by LIB.exe from the
> MSVC installation.
>
> lib.exe /machine:i386 /def:libhellodll.def
>
> Then I create the following code in MSVC
> // testdll.cpp : Defines the entry point for the console application.
> //
> #include "stdafx.h"
> #include "dll.h"
>
> int _tmain(int argc, _TCHAR* argv[])
> {
>         MyClass hello;
>         return 0;
> }
>
> I also add libhellodll.lib to MSVC project
> But when my testdll is linking I got the following errors
>
> testdll2 error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall MyClass::MyClass(void)" (__imp_??0MyClass@@QAE@XZ) referenced in function _main
> testdll2 error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall MyClass::~MyClass(void)" (__imp_??1MyClass@@UAE@XZ) referenced in function _main
> testdll2 fatal error LNK1120: 2 unresolved externals
>
>
> Then I tried to use dlltool from MinGW
> dlltool.exe -d libhellodll.def --dllname hellodll.dll --output-lib libhellodll.lib
>
> But I`ve got the same error
> I also tried to use dlltool.exe with -U and -k flags, I`ve got the
> same errors :(
>
> Can anybody help me?
> Excuse me for my poor english
>
> --
> Dmitry
>
>
>
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