struct S { void bar() { } }
final class FC { void foo(); }
class C
{
    void bar() { }
    final void foo();
}
static assert(!isFinalFunction!(int));
static assert(!isFinalFunction!(S.bar));
static assert( isFinalFunction!(FC.foo));
static assert(!isFinalFunction!(C.bar));
static assert( isFinalFunction!(C.foo));