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std::atomic_ref<T>::fetch_or

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std::atomic_ref

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atomic_ref::operator+=atomic_ref::operator-=

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atomic_ref::operator++atomic_ref::operator++(int)atomic_ref::operator--atomic_ref::operator--(int)

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atomic_ref::fetch_and

atomic_ref::fetch_or

atomic_ref::fetch_xor

atomic_ref::operator&=atomic_ref::operator|=atomic_ref::operator^=

atomic_ref::is_always_lock_free

atomic_ref::required_alignment

Provided only when T is an integral type other than cv bool

value_type fetch_or( 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 OR 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.

[edit] Parameters

arg - the other argument of bitwise OR

order - memory order constraints to enforce

[edit] Return value

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

[edit] 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_or` was meaningless for const T	constrained to accept only non-const `T`

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