VS 2010: error LNK2019: unresolved external symbol "extern "C" void * __cdecl

Question

I'm new in C++, I tried to copy this code and run in visual studio 2010. But it is giving unresolved extern 'c' error and another unresolved token "extern "C" as listed below the code.

This is the code causing the errors :

#ifdef _MANAGED     // Works only with managed C++
#pragma once
#pragma managed(push, on)
#include <stdlib.h>     //free

typedef void (__cdecl *_PVFV)(void);
extern "C" void * __cdecl _decode_pointer(void *);
extern "C" void * __cdecl _encoded_null();

// crtdll.c
extern "C" _PVFV *__onexitbegin;
extern "C"  _PVFV *__onexitend;



void CrtDestroyStatics(void)
{
    _PVFV * onexitbegin = (_PVFV *)_decode_pointer(__onexitbegin);
    if (onexitbegin)
    {
        _PVFV * onexitend = (_PVFV *)_decode_pointer(__onexitend);
        _PVFV function_to_call = NULL;

        /* save the start and end for later comparison */
        _PVFV * onexitbegin_saved = onexitbegin;
        _PVFV * onexitend_saved = onexitend;

        while (1)
        {
            _PVFV * onexitbegin_new = NULL;
            _PVFV * onexitend_new = NULL;

            /* find the last valid function pointer to call. */
            while (--onexitend >= onexitbegin && (*onexitend == NULL || *onexitend == _encoded_null()))
            {
                /* keep going backwards. */
            }

            if (onexitend < onexitbegin)
            {
                /* there are no more valid entries in the list, we are done. */
                break;
            }

            /* cache the function to call. */
            function_to_call = (_PVFV)_decode_pointer(*onexitend);

            /* mark the function pointer as visited. */
            *onexitend = (_PVFV)_encoded_null();

            /* call the function, which can eventually change __onexitbegin and __onexitend */
            (*function_to_call)();

            onexitbegin_new = (_PVFV *)_decode_pointer(__onexitbegin);
            onexitend_new = (_PVFV *)_decode_pointer(__onexitend);

            if ( ( onexitbegin_saved != onexitbegin_new ) || ( onexitend_saved != onexitend_new ) )
            {
                /* reset only if either start or end has changed */
                 __onexitbegin = onexitbegin_saved = onexitbegin_new;
                 __onexitend = onexitend_saved = onexitend_new;
            }

            break;
        }
        /*
        * free the block holding onexit table to
        * avoid memory leaks.  Also zero the ptr
        * variables so that they are clearly cleaned up.
        */

        free ( onexitbegin ) ;

        __onexitbegin = __onexitend = (_PVFV *)_encoded_null();
    }

} //CrtDestroyStatics

#pragma managed(pop)
#endif

And here is the linker errors:

Error   4   error LNK2019: unresolved external symbol "extern "C" void * __cdecl _decode_pointer(void *)" (?_decode_pointer@@$$J0YAPEAXPEAX@Z) referenced in function "void __cdecl CrtDestroyStatics(void)" (?CrtDestroyStatics@@$$FYAXXZ)
Error   3   error LNK2028: unresolved token (0A000F2F) "extern "C" void * __cdecl _decode_pointer(void *)" (?_decode_pointer@@$$J0YAPEAXPEAX@Z) referenced in function "void __cdecl CrtDestroyStatics(void)" (?CrtDestroyStatics@@$$FYAXXZ)

Although I have those libraries values inherited for Additional Dependencies in Linker->Input

kernel32.lib
user32.lib
gdi32.lib
winspool.lib
comdlg32.lib
advapi32.lib 

Please tell me what wrong I have committed?

Answer 1

If _decode_poiner is not available in your kernel32, it seems that your configuration is not correctly setup. If you had an older version of VS and upgraded, make sure that the linker doesn't point to the old environment.

You can check here for additional information on how to solve this.