C++11 is a revolution to C++, adding many essential features (such as std:: unordered_map) and new syntactic constructs (e.g. rvalue references, lambdas). Interfaces, e.g. header files, have to be understood also by C++ novices. Limiting the exposed features is already common for C++ 2003[2], and will likely be necessary for C++11, even for the bravest programmers. This contribution explains why a compiler is the ideal tool for enforcing such rules, and what the options are for implementing it. It proposes clang, the LLVM-based C++ compiler front-end as an example implementation.