[Bug libstdc++/94033] is_trivially_copy_constructible<> fails with compiler error on complicated object with private default constructor

[avi@cloudius-systems.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94033

--- Comment #2 from Avi Kivity <avi@cloudius-systems.com> ---
It does not look similar to 93923. There, there is an incomplete type. In my
reproducer the type is complete but the default constructor is private.

Note that for simple cases is_trivially_constructible works (and evaluates to
false), both in gcc 9 and gcc 10. It is only in a few cases that it starts to
fail.

The errors are also very different from 93983.