[Bug libstdc++/93059] char and char8_t does not talk with each other with memcpy. std::copy std::copy_n, std::fill, std::fill_n, std::uninitialized_copy std::uninitialized_copy_n, std::fill, std::uninitialized_fill_n fails to convert to memxxx functions

[euloanty at live dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93059

--- Comment #1 from fdlbxtqi <euloanty at live dot com> ---
I am going to rewrite these functions by C++20 concepts + if constexpr for
C++20 for you, Jwakely. I do not believe these enable-if/ overloading functions
would not be a problem.