# std::experimental::propagate_const<T>::swap

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constexpr void swap( propagate_const & pt ) noexcept(/* see below */); |  | (library fundamentals TS v2)

Swaps the wrapped pointer with that of pt. Let `t_` designate the private data member that is the wrapped pointer-like object, then this function is equivalent to swap(t_, pt.t_), where the overload resolution for `swap` is performed among std::swap and any declaration found by the usual lookup rules, as described in Swappable.

The behavior is undefined if lvalues of `T` do not satisfy Swappable.

### Parameters

pt | - | another `propagate_const` object to swap with

### Exceptions

`noexcept` specification: noexcept(noexcept(swap(t_, pt.t_))) The lookup for the identifier `swap` in the exception specification finds overloads described above, and does not find the member function itself, making the exception specification equivalent to C++17 std::is_nothrow_swappable. | (library fundamentals TS v2)
`noexcept` specification: noexcept(std::is_nothrow_swappable_v<T>) | (library fundamentals TS v3)

### 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 3413 | LFTSv2 | the exception specification was ill-formed | made well-formed

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