std::atomic_ref<T>::fetch_and

std::atomic_ref<T>::fetch_and - cppreference.com

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Provided only when `T` is an integral type other than cv `bool`
`value_type fetch_and( value_type arg, std::memory_order order = std::memory_order_seq_cst ) const noexcept;`		(since C++20)

Atomically replaces the current value of the referenced object with the result of bitwise AND of the value and arg. This operation is a read-modify-write operation. Memory is affected according to the value of order.

This overload participates in overload resolution only if std::is_const_v<T> is false.

Parameters

arg	-	the other argument of bitwise AND
order	-	memory order constraints to enforce

Return value

The value of the referenced object, immediately preceding the effects of this function.

Example

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3508 (P3323R1)	C++20	`fetch_and` was meaningless for `const T`	constrained to accept only non-const `T`