Library ABI compatibility between versions of Visual Studio

Question

I have two scenarios. Suppose I have 3 shared libraries that export C++ symbols, each built with VS7.1, VS8, and VS9. I compile all 3 in VS9. For some reason, this works. I

Answer 1

The issue may be not only in ABI differences (calling conventions, etc.) between these VS versions, but also in removed/changed symbols in system DLL libraries. See this table for the detailed comparison of system DLL libraries between VS8 (2005, Windows SDK 5.0) and VS9 (2008, Windows SDK 6.0).

See also compatibility matrix for Windows SDKs.