I have a native c++ exe using the /MTd runtime library. I cannot change this option as I dont have much control over the build of this exe. I need to call a CLI C++ dll in this exe which returns a class with STL vector member variables. At the return of the CLI C++ method, I get a heap corruption error. From my analysis, this happens because there are two different CRTs and the vectors deallocate method is running in the native CRT and bombs due to invalid address.
How do I return a vector from a CLI C++ dll which is compiled with a different CRT to run with my native exe?
Your assessment is correct -- allocations performed inside one CRT cannot be deallocated inside a different CRT. It's a simple rule, and there's no way around it.
You need to build both modules with the same runtime library settings, or you need to transfer only POD-types between module boundaries.