# __has_trivial_copy_constructor

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**Category**

Type Trait Functions

**Syntax**

bool __has_trivial_copy_constructor ( typename T )

Returns true if and only if T has a trivial default constructor.

**Error** if T is an incomplete type.

False (but well-formed) if a class type does not have a default constructor

The definition (from Section 20.4.4.3 of the Working Draft) notes has a type T has a trivial copy constructor if it is in the list::

- a scalartype (or array thereof)
- a reference type (or array thereof)
- an array of class type with trivial destructor
- a class type with a trivial copy constructor (12.8)

According to Section 12.8 p6 of the Working Draft:

A copy constructor for class X is trivial if:

- It is not user provided (see Section 8.4)
- class X has no virtual functions
- class X has no virtual base classes
- each direct base class of X has a trivial copy constructor.
- for all the non-static data members of X that are of class type (or array thereof), each such class type has a trivial copy constructor;.

A copy constructor is not user provided if it is implicitly declared, or defined inline as = default;

**Ox interaction** false if the default constructor is defined as deleted.

**Ox interaction**with default function definitions.