NAME

std::convertible_to - std::convertible_to

Synopsis

Defined in header <concepts>
template< class From, class To >

concept convertible_to =
std::is_convertible_v<From, To> && (since C++20)
requires {
static_cast<To>(std::declval<From>());

};

The concept convertible_to<From, To> specifies that an expression of the same type
and value category as those of std::declval<From>() can be implicitly and explicitly
converted to the type To, and the two forms of conversion produce equal results.

Semantic requirements

convertible_to<From, To> is modeled only if, given a function fun of type
std::add_rvalue_reference_t<From>() such that the expression fun() is
equality-preserving,

* Either
* To is neither an object type nor a reference-to-object type, or
* static_cast<To>(fun()) is equal to []() -> To { return fun(); }(), and
* One of the following is true:
* std::add_rvalue_reference_t<From> is not a reference-to-object type, or
* std::add_rvalue_reference_t<From> is an rvalue reference to a
non-const-qualified type, and the resulting state of the object referenced
by fun() is valid but unspecified after either expression above; or
* the object referred to by fun() is not modified by either expression above.

Equality preservation

Expressions declared in requires expressions of the standard library concepts are
required to be equality-preserving (except where stated otherwise).

See also

is_convertible
is_nothrow_convertible checks if a type can be converted to the other type
(C++11) (class template)
(C++20)