On Fri, Aug 20, 2021 at 10:43 AM DBJ via Std-Proposals <std-proposals@lists.isocpp.org> wrote:
Thus I am wondering what was/is wrong with using C++20 require, for example?
Not 100% sure what the question is, and obviously I am not author of the code you mention, but I think static_assert code is more easier to write/maintain, and gives nicer error message to user.  I would personally use requires/concepts just for template overloading or when concept is clear without any text message to user, e.g. std::floating_point.