[meta.trans] (original) (raw)

template<class T>
struct type_identity;

The member typedef type denotes T.

template<class T>
struct remove_cvref;

template<class T>
struct decay;

Otherwise the member typedef type denotes remove_cv_t<U>.

template<bool B, class T = void> struct enable_if;

If B is true, the member typedef type denotes T; otherwise, there shall be no membertype.

template<bool B, class T, class F>
struct conditional;

If B is true, the member typedef type denotes T.

If B is false, the member typedef type denotes F.

template<class... T> struct common_type;

Unless this trait is specialized, the member type is defined or omitted as specified below.

If it is omitted, there shall be no member type.

Each type in the template parameter pack T shall be complete, cv void, or an array of unknown bound.

Unless this trait is specialized, there shall be no member type.

template<class... T> struct common_reference;

The member typedef-name type is defined or omitted as specified below.

Each type in the parameter pack T shall be complete or cv void.

template<class T>
struct underlying_type;

If T is an enumeration type, the member typedef type denotes the underlying type of T ([dcl.enum]); otherwise, there is no member type.

template<class Fn,
class... ArgTypes>
struct invoke_result;

If the expression INVOKE(declval<Fn>(), declval<ArgTypes>()...) ([func.require]) is well-formed when treated as an unevaluated operand ([expr.context]), the member typedef type denotes the typedecltype(INVOKE(declval<Fn>(), declval<ArgTypes>()...)); otherwise, there shall be no member type.

Access checking is performed as if in a context unrelated to Fn andArgTypes.

Only the validity of the immediate context of the expression is considered.

Preconditions: Fn and all types in the template parameter pack ArgTypes are complete types, cv void, or arrays of unknown bound.

template<class T> struct unwrap_reference;

If T is a specialization reference_wrapper<X> for some type X, the member typedef type of unwrap_reference<T> denotes X&, otherwise type denotes T.