The Safe C++ Extensions proposal contrasts ISO C++ with Safe C++. “In ISO C++, soundness bugs often occur because caller and callee don’t know who should enforce preconditions, so neither of them do. In Safe C++, there’s a convention backed up by the compiler, eliminating this confusion and improving software quality.”
In the introduction to the proposal, the C++ Alliance acknowledges issues with the language. “Much of the country’s critical infrastructure relies on software written in C and C++, languages which are very memory-unsafe, leaving these systems more vulnerable to exploits by adversaries.” However, Safe C++ developers would be prohibited from writing operations that may result in undefined behaviors that compromise lifetime safety, type safety, or thread safety.