# std::ranges::iter_move

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Defined in header `<iterator>` |  |
inline namespace /* unspecified */ { inline constexpr /* unspecified */ iter_move = /* unspecified */; } |  | (since C++20) (customization point object)
Call signature |  |
template< class T > requires /* see below */ constexpr decltype(auto) iter_move( T&& t ) noexcept(/* see below */); |  | (since C++20)

Obtains an rvalue reference or a prvalue temporary from a given iterator.

A ranges::iter_move(t) is expression-equivalent to:

1. iter_move(t), if t has a class or enumeration type and the expression is well-formed when treated as an unevaluated operand, where the overload resolution of `iter_move` is performed only with the candidates found by argument-dependent lookup.
2. Otherwise, std::move(*t) if *t is well-formed and is an lvalue.
3. Otherwise, *t if *t is well-formed and is an rvalue.

In all other cases, a call to `ranges::iter_move` is ill-formed, which can result in substitution failure when ranges::iter_move(e) appears in the immediate context of a template instantiation.

If ranges::iter_move(e) is not equal to *e, the program is ill-formed, no diagnostic required.

### Customization point objects

The name `ranges::iter_move` denotes a customization point object, which is a const function object of a literal `semiregular` class type. For exposition purposes, the cv-unqualified version of its type is denoted as `__iter_move_fn`.

All instances of `__iter_move_fn` are equal. The effects of invoking different instances of type `__iter_move_fn` on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus, `ranges::iter_move` can be copied freely and its copies can be used interchangeably.

Given a set of types `Args...`, if std::declval <Args>()... meet the requirements for arguments to `ranges::iter_move` above, `__iter_move_fn` models

- std::invocable <__iter_move_fn, Args...>,
- std::invocable <const __iter_move_fn, Args...>,
- std::invocable <__iter_move_fn&, Args...>, and
- std::invocable <const __iter_move_fn&, Args...>.

Otherwise, no function call operator of `__iter_move_fn` participates in overload resolution.

### Example

| This section is incomplete Reason: no example

### See also

iter_move (C++20) | casts the result of dereferencing the adjusted underlying iterator to its associated rvalue reference type (function)
iter_move (C++20) | casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function)

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