[meta.unary.comp]

These templates provide convenient compositions of the primary type categories, corresponding to the descriptions given in subclause [basic.types].

For any given type T, the result of applying one of these templates to T and to cv T shall yield the same result.

Table 45 — Composite type category predicates

Template	Condition	Comments
template<class T> struct is_reference;	T is an lvalue reference or an rvalue reference
template<class T> struct is_arithmetic;	T is an arithmetic type
template<class T> struct is_fundamental;	T is a fundamental type
template<class T> struct is_object;	T is an object type
template<class T> struct is_scalar;	T is a scalar type
template<class T> struct is_compound;	T is a compound type
template<class T> struct is_member_pointer;	T is a pointer-to-member type

19 General utilities library [utilities]