What is a non-trivial destructor in C++?

Question

I was reading this which mentions destructors being trivial and non-trivial.

A class has a non-trivial destructor if it either has an explicitly def

Answer 1

So you mean, the entire declaration of C is this:

class C { };

?

Then, yes: Since C has no member objects and no base classes, it therefore has no member objects with non-trivial destructors and no base classes with non-trivial destructors, so its implicitly-defined destructor is a trivial one.