[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 #12 from fdlbxtqi <euloanty at live dot com> ---
(In reply to Marc Glisse from comment #8)
> (In reply to fdlbxtqi from comment #6)
> > void copy_char_vector_with_iter(std::vector<char8_t>::iterator
> > out,std::vector<char> const& bits)
> > {
> >     std::copy_n(bits.begin(),bits.size(),out);
> > }
> > 
> > https://godbolt.org/z/_yA_Ls
> > See the assembly
> 
> Thanks, I just filed PR 93063 about a subpart that the compiler should be
> able to do without help from the library.

I think the implementation is still problematic since C++ 20 adds the
contiguous_iterator concept. The current implementation looks not to allow
custom 
 contiguous iterators types to be optimized as memmove.

It needs certain kinds of revamping IMO.