3 Terms and definitions [intro.defs]

Only glvalues of scalar type ([basic.types.general]) can be used to access objects.

Reads of scalar objects are described in [conv.lval] and modifications of scalar objects are described in [expr.assign], [expr.post.incr], and [expr.pre.incr] .

Attempts to read or modify an object of class type typically invoke a constructor or assignment operator; such invocations do not themselves constitute accesses, although they may involve accesses of scalar subobjects.