The C++ front end implements syntactic extensions that allow compile-time determination of various characteristics of a type (or of a pair of types).
__has_nothrow_assign (type)If type is const qualified or is a reference type then the trait is
false. Otherwise if __has_trivial_assign (type) is true then the trait
is true, else if type is a cv class or union type with copy assignment
operators that are known not to throw an exception then the trait is true,
else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__has_nothrow_copy (type)If __has_trivial_copy (type) is true then the trait is true, else if
type is a cv class or union type with copy constructors that
are known not to throw an exception then the trait is true, else it is false.
Requires: type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__has_nothrow_constructor (type)If __has_trivial_constructor (type) is true then the trait is
true, else if type is a cv class or union type (or array
thereof) with a default constructor that is known not to throw an
exception then the trait is true, else it is false. Requires:
type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__has_trivial_assign (type)If type is const qualified or is a reference type then the trait is
false. Otherwise if __is_pod (type) is true then the trait is
true, else if type is a cv class or union type with a trivial
copy assignment ([class.copy]) then the trait is true, else it is
false. Requires: type shall be a complete type, (possibly
cv-qualified) void, or an array of unknown bound.
__has_trivial_copy (type)If __is_pod (type) is true or type is a reference type
then the trait is true, else if type is a cv class or union type
with a trivial copy constructor ([class.copy]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_trivial_constructor (type)If __is_pod (type) is true then the trait is true, else if
type is a cv class or union type (or array thereof) with a
trivial default constructor ([class.ctor]) then the trait is true,
else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_trivial_destructor (type)If __is_pod (type) is true or type is a reference type then
the trait is true, else if type is a cv class or union type (or
array thereof) with a trivial destructor ([class.dtor]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_virtual_destructor (type)If type is a class type with a virtual destructor
([class.dtor]) then the trait is true, else it is false. Requires:
type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__is_abstract (type)If type is an abstract class ([class.abstract]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_base_of (base_type, derived_type)If base_type is a base class of derived_type
([class.derived]) then the trait is true, otherwise it is false.
Top-level cv qualifications of base_type and
derived_type are ignored. For the purposes of this trait, a
class type is considered is own base. Requires: if __is_class
(base_type) and __is_class (derived_type) are true and
base_type and derived_type are not the same type
(disregarding cv-qualifiers), derived_type shall be a complete
type. A diagnostic is produced if this requirement is not met.
__is_class (type)If type is a cv class type, and not a union type
([basic.compound]) the trait is true, else it is false.
__is_empty (type)If __is_class (type) is false then the trait is false.
Otherwise type is considered empty if and only if: type
has no non-static data members, or all non-static data members, if
any, are bit-fields of length 0, and type has no virtual
members, and type has no virtual base classes, and type
has no base classes base_type for which
__is_empty (base_type) is false. Requires: type shall
be a complete type, (possibly cv-qualified) void, or an array
of unknown bound.
__is_enum (type)If type is a cv enumeration type ([basic.compound]) the trait is
true, else it is false.
__is_literal_type (type)If type is a literal type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__is_pod (type)If type is a cv POD type ([basic.types]) then the trait is true,
else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__is_polymorphic (type)If type is a polymorphic class ([class.virtual]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_standard_layout (type)If type is a standard-layout type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_trivial (type)If type is a trivial type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_union (type)If type is a cv union type ([basic.compound]) the trait is
true, else it is false.
__underlying_type (type)The underlying type of type. Requires: type shall be
an enumeration type ([dcl.enum]).