Need for declare destructor as default

Question

According to these guidelines:

If the default destructor is needed, but its generation has been suppressed (e.g., by defining a move constructor), use =default.

I can't imagine when code would be ill-formed without explicit default destructor in class which has move constructor.

Can somebody show me example confirms quote above?

struct S {
    S() {};
    S( S&& ) {}; // move ctor
};

int main() {
    S s; // there is no need to declare dtor explicitly =default
}

Answer 1

I think it would be some kind of mistake, the implicit declaration of default destructor should have nothing to do with the definition of a move constructor.

From the standard, 12.4$4,5 Destructors [class.dtor]

4 If a class has no user-declared destructor, a destructor is implicitly declared as defaulted (8.4). An implicitly-declared destructor is an inline public member of its class.

5 A defaulted destructor for a class X is defined as deleted if:

(5.1) — X is a union-like class that has a variant member with a non-trivial destructor,

(5.2) — any potentially constructed subobject has class type M (or array thereof) and M has a deleted destructor or a destructor that is inaccessible from the defaulted destructor,

(5.3) — or, for a virtual destructor, lookup of the non-array deallocation function results in an ambiguity or in a function that is deleted or inaccessible from the defaulted destructor.