[Bug c++/117046] -Wclass-memaccess provides misleading diagnostics on std::memcpy

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117046

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
      else if (!trivial
               && !VOID_TYPE_P (srctype)
               && !is_byte_access_type (srctype)
               && !same_type_ignoring_top_level_qualifiers_p (desttype,
                                                              srctype))

When you use bytes.data() the src type is unsigned char which is a "byte access
type" and so g++ doesn't warn. When you use &bytes it's not copying from
unsigned char.

So the warning really is telling you that Foo is non-trivial (which is
correct), but the warning is suppressed when copying from unsigned char*

I think this is working as designed.