A fair point, but the major C++ compilers don't make much effort in letting you define a subset to permit. For contrast, the Ada language (which is larger than

A fair point, but the major C++ compilers don't make much effort in letting you define a subset to permit. For contrast, the Ada language (which is larger than C but smaller than C++) takes this idea quite seriously. There are various 'well known' subsets of Ada with interesting properties and tooling. These subsets are called profiles. There's SPARK, a very minimalist subset tailored for formal verification, and Ravenscar, for concurrent hard real-time systems. Profile compliance is checked by the compiler itself. (If I understand correctly, the profiles are defined using Ada's rough equivalent of #pragma in C and C++.) In the C and C++ worlds there are subsets like Google's C++ style guide, LLVM's C++ style guide, MISRA C, and MISRA C++, but their tools (i.e. static analysis tools to check for compliance) are generally separate from the compiler, for what that's worth.