Section: 22.8.7.4 [expected.void.assign] Status: New Submitter: Jiang An Opened: 2023-12-16 Last modified: 2023-12-22 10:28:38 UTC
Priority: Not Prioritized
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Discussion:
It seems intended that copy functions of std::optional, std::variant, and std::expected are conditionally deleted, while move functions are constrained. However, the move assignment operator of std::expected<cv void, E> is currently conditionally deleted, which is inconsistent.
Proposed resolution:
This wording is relative to N4971.
Modify 22.8.7.4 [expected.void.assign] as indicated:
constexpr expected& operator=(expected&& rhs) noexcept(see below);-?- Constraints: is_move_constructible_v<E> is true and is_move_assignable_v<E> is true.
[…] -6- Remarks: The exception specification is equivalent to is_nothrow_move_constructible_v<E> && is_nothrow_move_assignable_v<E>.-7- This operator is defined as deleted unless is_move_constructible_v<E> is true and is_move_assignable_v<E> is true.