VS2012 C++ warning C4005: '__useHeader': macro redefinition

Question

While migrating an old C++ project from Visual Studio 6 up to Visual Studio 2012, we came across an odd set of warnings from inside the standard Microsoft platform headers:<

Answer 1

I had this problem in some projects that originated with VC++ 2003 and have been incrementally upgraded over the years. I found that while the project settings had %(PreprocessorDefinitions) in Preprocessor Definitions, a few of the .cpp files didn't (The oldest ones). After changing them to "Inherit from parent or project defaults" it got rid of the warnings.