std::convertible_to

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Concepts library

Core language concepts
same_as (C++20)
derived_from (C++20)
convertible_to (C++20)
common_reference_with (C++20)
common_with (C++20)
integral (C++20)
signed_integral (C++20)
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swappableswappable_with (C++20)(C++20)
destructible (C++20)
constructible_from (C++20)
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copy_constructible (C++20)
assignable_from (C++20)

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equality_comparableequality_comparable_with (C++20)(C++20)
totally_orderedtotally_ordered_with (C++20)(C++20)
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movable (C++20)
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invocableregular_invocable (C++20)(C++20)
predicate (C++20)
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equivalence_relation (C++20)
strict_weak_order (C++20)

Exposition-only concepts
boolean-testable (C++20)

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Defined in header`<concepts>`
template<class From,class To> concept convertible_to= std::is_convertible_v<From, To>&& requires{ static_cast<To>(std::declval<From>()); };		(since C++20)

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

[edit]Semantic requirements

convertible_to<From, To> is modeled only if, given a functionfun of typestd::add_rvalue_reference_t<From>() such that the expressionfun() isequality-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 byfun() is valid but unspecified after either expression above; or
- the object referred to byfun() is not modified by either expression above.