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It’s not semantically safe to pass arbitrary vectors into a generic buffer copying function. The T in a vector<T> could have internal pointers or worse things.

Either the objects are simple and trivially copiable, or you need a proper serialization library.

Sure you can use span to generalize slides and iteration, but I don’t think that’s the point of the article.

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In comparison to a plain void* and a separate size, it's still an improvement. As others mentioned, void* suffers from the same problem (it might point to a type that is not trivially copyable), except it has more opportunities for mistakes.

In contrast, with span, you can instantiate only to span<uint_8> (or something similar) and you'd still be able to accept other buffer types (such as vector<uint_8>, array<uint_8>, etc.). Alternatively, you can make T bounded to be trivially copyable. You can't do that with void*.

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