I'm trying to make an inter-compiler compatible class in a dll built with mingw that can be used in a Windows VS application. My issue is, my class crashes the moment it tries to initialize a member variable when a function is called from the VS program. Using the STL or making local variables within the same functions works fine.
Unhandled exception at 0x6BEC19FE (test.dll) in ConsoleApplication2.exe: 0xC0000005: Access violation writing location 0x154EB01E.
Simple demonstration:
The dll code
#include <iostream>
class Tester
{
public:
virtual void test() = 0;
};
class TesterImp : public Tester
{
public:
TesterImp(){}
~TesterImp(){}
virtual void test() {
int test = 5; // fine
m_test = 5; // access violation
}
private:
int m_test;
};
extern "C"
{
__declspec (dllexport) Tester* Create()
{
return new TesterImp();
}
}
Main program that loads the dll and calls the test function:
#include <iostream>
#include <Windows.h>
class Tester
{
public:
virtual void test() = 0;
};
typedef Tester* (*createPtr)();
int main(int argc, const char **argv, char * const *envp) {
HINSTANCE hGetProcIDDLL = LoadLibraryA("test.dll");
if (hGetProcIDDLL == NULL) {
std::cout << "could not load the dynamic library" << std::endl;
return EXIT_FAILURE;
}
createPtr ctr = (createPtr)GetProcAddress(hGetProcIDDLL, "Create");
if (!ctr) {
std::cout << "could not locate the function" << std::endl;
return EXIT_FAILURE;
}
std::cout << "dll loading success!" << std::endl;
Tester* testf = ctr();
std::cout << "Got test class" << std::endl;
testf->test(); // crash if the member variable is referenced, fine otherwise with local variable initialization or STL use inside the function
std::cout << "Running dll functions success!" << std::endl;
return 0;
}
Main program is compiled in debug mode with VS2012 and the dll is built using g++ from mingw -
g++ -shared -o test.dll test.cpp
Could someone explain this behavior for me, please?
Thank you.
