On certain error cases ATL invokes AtlThrow() which is implemented as ATL::AtlThrowImpl() which in turn throws CAtlException. The latter is not very good - CAtlException is not even derived from std::exception and also we use our own exceptions hierarchy and now we will have to catch CAtlException separately here and there which is lots of extra code and error-prone.

Looks like it is possible to replace ATL::AtlThrowImpl() with my own handler - define _ATL_CUSTOM_THROW and define AtlThrow() to be the custom handler before including atlbase.h - and ATL will call the custom handler.

Not so easy. Some of ATL code is not in sources - it comes compiled as a library - either static or dynamic. We use the static - atls.lib. And... it is compiled in such way that it has ATL::ThrowImpl() inside and some code calling it. I used a static analysis tool - it clearly shows that there're paths on which the old default handler is called.

To ensure I even tried to "reimplement" ATL::AtlThrowImpl() in my code. Now the linker says it sees two declarations of ATL::AtlThrowImpl() which I suppose confirms that there's another implementation that can be called by some code.

How can I handle this? How do I replace the default handler completely and ensure that the default handler is never called?