C++ – How to find the cause of this linker error

clibcmtdmsvcrtvisual c++

After going through a lengthy process to rename a project, my DLL project will not build in Debug mode (Release builds work):

MSVCRTD.lib(msvcr90d.dll) : error LNK2005: _CrtDbgReportW already defined in LIBCMTD.lib(dbgrpt.obj)

This project, and the five static libraries it depends on, are set to use "Multi-threaded Debug (/MTd)" (under C/C++|Code Generation|Runtime Library). I believe LIBCMTD.lib is the one for multi-threaded debug, but what is MSVCRTD.lib, and what could be causing this error?

If it makes a difference, this DLL is for Windows CE.

Best Answer

LIBCMT is what you need for /MT, MSVCRT is what you need for /MD. You are linking .obj and .lib files that were mixed, some compiled with /MT some with /MD. That's not good.

Usually it is the .lib files that cause the problem. Review their build settings and make sure their /M option is the same as your DLL project.

Also, beware of the trouble you can get into if the DLL was compiled with /MT. You'll have major problems when the DLL returns pointers to objects that the client needs to release. It can't, it doesn't use the same memory allocator.

Related Solutions

C++ – How to iterate over the words of a string

I use this to split string by a delimiter. The first puts the results in a pre-constructed vector, the second returns a new vector.

#include <string>
#include <sstream>
#include <vector>
#include <iterator>

template <typename Out>
void split(const std::string &s, char delim, Out result) {
    std::istringstream iss(s);
    std::string item;
    while (std::getline(iss, item, delim)) {
        *result++ = item;
    }
}

std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, std::back_inserter(elems));
    return elems;
}

Note that this solution does not skip empty tokens, so the following will find 4 items, one of which is empty:

std::vector<std::string> x = split("one:two::three", ':');

C++ – How to use CLR in a different runtime environments under multiple projects in visualstudio

All the dlls you link to using import libraries must have the same setting as the application for how you link to the runtime library. The errors are showing that you are mixing use of the runtime as a .dll (MSVCRTD) and as a .lib (LIBCMTD).

Best Answer

Related Solutions

C++ – How to iterate over the words of a string

C++ – How to use CLR in a different runtime environments under multiple projects in visualstudio

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