[Bug libstdc++/69354] std::thread doesn't support move-only callable objects

[anthony.ajw at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69354

--- Comment #3 from Anthony Williams <anthony.ajw at gmail dot com> ---
I hadn't noticed I had omitted the const!

Surely the intent of 12.8p11.2 is that if you can't actually copy the bases
and/or members with the specified signature then the defaulted copy constructor
is deleted?

Are you going to file the DR or shall I?

Potential core defect aside, I still think this class should work with
std::thread, as it fits the MoveConstructible requirement.