unresolved external symbol due to name mangling

Question

I am facing linker error for a XERCES function while upgrading it from 2.6 to 2.8

unresolved external symbol (?resolveEntity@HandlerBase@xercesc_2_8@@UAEPAVInputSource@2@QBG0@Z)

I checked the xerces-c_2.8.lib and found that name lib is bit different that the one in my .obj file It is as shown

?resolveEntity@HandlerBase@xercesc_2_8@@UAEPAVInputSource@2@QB_W0@Z

So I understand that linker wont find the match and throw error.

But I am unable to understand why my .obj file contains different signature.

code is including correct header files and lib from still incorrect name.

Any help would be appreciated.

Answer 1

You can use the undname.exe utility to recover the original C++ declaration.

?resolveEntity@HandlerBase@xercesc_2_8@@UAEPAVInputSource@2@QBG0@Z converts to:

virtual class xercesc_2_8::InputSource * 
__thiscall xercesc_2_8::HandlerBase::resolveEntity(
    unsigned short const * const,
    unsigned short const * const)

?resolveEntity@HandlerBase@xercesc_2_8@@UAEPAVInputSource@2@QB_W0@Z converts to:

virtual class xercesc_2_8::InputSource * 
__thiscall xercesc_2_8::HandlerBase::resolveEntity(
     wchar_t const * const,
     wchar_t const * const)

Note the differences in the argument types, unsigned short vs wchar_t. For some reason, your compiler is not recognizing the wchar_t type. That could be because you have a very old compiler. Or it can be an option set wrong, on msvc it is C/C++, Language, "Treat wchar_t as Built-in type". Or you've got a macro that hacks the string type to unsigned short.