The bigger problem is that std::vector::at() is kinda useless in any case since it's very rare in idiomatic C++ to be indexing into a vector using an integer. Y

The bigger problem is that std::vector::at() is kinda useless in any case since it's very rare in idiomatic C++ to be indexing into a vector using an integer. You're much more likely to be using an iterator, since that's what you'll get from standard algorithms like std::find() etc. And there's no API for "checked iterators" that is equivalent to at(). For a debug build, your STL implementation might use checked iterators, but that's a quality of implementation matter that you can't rely on. MSVC does have a documented checked iterator facility that can be enabled even in release builds: https://learn.microsoft.com/en-us/cpp/standard-library/checked-iterators https://learn.microsoft.com/en-us/cpp/standard-library/check....