How can you modify an object without calling member functions?

Question

At 3.10/10, the standard says:

An lvalue for an object is necessary in order to modify the object except that an rvalue of class type can also be used to

Answer 1

Modifying a temporary and not through an lvalue to that temporary:

#include 

class standard_layout {
    standard_layout();
    int stuff;
};

standard_layout* global;

standard_layout::standard_layout()
{ global = this; }

void
modify(int)
{
    std::memset(global, 0, sizeof *global);
}

int
main()
{
    modify( (standard_layout {}, 0) );
}

I don't think it's correct to assume that rvalues of class types are non-modifiable. I now understand that paragraph as 'for non-class types, an lvalue for an object is needed in order to modify that object'.