[Bug c++/95772] warning desired when default operator= cannot be constructued

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95772

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
No, =default means "do the right thing" which sometimes means deleting it.

In class templates that is especially true, where you don't know the properties
of the types used as data members or base classes.