If depends on the compiler, and is not a problem at all, just because all needed for compilation is indicated in the source code. I don't think a reasonable compiler design should tread a constant function separately from other members. Being constant or not is just one of the many attributes of a class member. Of course the compiler code keeps the parsed member information is some data structure; what's so special about it?
We do not have access to the source code of this particular compiler, Microsoft VC++. If you want to know such detail, consider looking at, for example, the source code of GNU C++:
The source code can be found here: