基于Visual Studio 2005构建的C ++ Exe是否可以动态加载基于Visual Studio 2015构建的DLL

Question

Currently i have an third party visual studio application which was built on Visual studio 2005 and this application uses one of our DLL through the plugin framework. Recently this DLL(Client) was built on Visual studio 2015, will this cause the third party application to crash?

Can someone explain how the run time of visual c++ works in such cases

Answer 1

It's actually not a runtime. Really during dll load there is no difference if the DLL was built in VS2015 or VS2005 if interfaces match.

They will match however only if the library has C-like or COM-like interface.

Also as already mentioned in comments, the CRT libraries are not compatible, but there can be a solution:

Any DLL can be linked against different CRT versions, it's what is specified with /MT /MD /MTd so on options https://msdn.microsoft.com/en-us/library/2kzt1wy3(v=vs.140).aspx If your library has static linkage with CRT (ie /MT or /MTd) it will not collide with an external environment. However to succeed you library has no right to free any memory gotten from the environment, neither that environment is allowed to free the memory obtained from you library. It usually means following the rule: the library which allocated memory has to free it. As a workaround you can use HeapAlloc function.

Additionally it's worth to mention that you have no any chance to succeed in case you use in interfaces any of STL containers. (std::vector, map, set so on) because they were changed drastically since 2005 year.

In case you have a cryptic linker errors which says something about CRT incompatibilities you can try def files to precisely specify what functions and variables are exported. You better to have C interface (you can use extern "C" construct to ensure symbol mangling doesn't add more troubles)