Achieving bounds safety in modern C++ requires a combination of compiler diagnostics and runtime protections. Clang's -Wunsafe-buffer-usage warning acts as the front line of C++ Safe Buffers, guiding codebases away from raw pointer arithmetic toward hardened abstractions in libc++ like std::span and std::array. This talk will survey the LLVM community's recent improvements to this diagnostic. In addition, we will share our experience driving the large-scale adoption of these technologies. This includes valuable lessons learned and real-world challenges discovered from large-scale source code refactoring guided by the diagnostic across a number of codebases, as well as the enabling of hardened libc++ for the entire user space of a large consumer-hardware operating system. Finally, we will discuss future steps for the memory safety effort.