The deliberate omission of std::span::at() is annoying. The paper that introduced std::span was titled "span: bounds-safe views for sequences of objects," but t

The deliberate omission of std::span::at() is annoying. The paper that introduced std::span was titled "span: bounds-safe views for sequences of objects," but there is actually no bounds checking in the standard. It's only true with debug builds that also use slow, debug versions of the STL, which have almost negligible value compared to just using sanitizers.