Well in that case, I guess it's a definition thing. When I teach C++, I find it much more useful to make a clear separation between 'preprocessor' and 'compiler

Well in that case, I guess it's a definition thing. When I teach C++, I find it much more useful to make a clear separation between 'preprocessor' and 'compiler', and not make the preprocessor part of the compiler and then make the... uh... 'actual compiler' also part of the compiler. When you take the preprocessed state of a compilation unit, by having the preprocessor write it out to disk, and show someone what the effects are of passing one or the other -D flag, or change the order of includes - that directly and concretely shows what is going on. And then this preprocessed file is passed on to the actual compiler. There is a clear separation between stages, easy to understand, and useful to boot when the time comes you have to debug an issue related to it and you want to look at the preprocessed file to see what's going.