[loeg]

I think we are in agreement that Microsoft does not implement Annex K as specified in ISO C. I don't fault them for that; I wouldn't either.

As to unergonomic, that's somewhat subjective. But I'm a long-time C practitioner and that's my feel of the API. Constraint handlers are a mistake. Ambient state that is not part of the function interface, as well as asynchronous interaction, make for poor APIs. Constraint handlers are a mismatch for library use of safe functions, as well as kernel environments.

Most functions seem pointless; e.g., snprintf_s. Re-adding gets() in the form of gets_s() seems unhelpful. Why bsearch_s, qsort_s, memcpy_s/memmove_s?? Do you really think strerror_s() is useful? Or strnlen_s()?