Created on 2023-01-06.00:00:00 last changed 21 months ago
Proposed resolution:
This wording is relative to N4917.
Modify [range.utility.conv.to] as indicated:
template<class C, input_range R, class... Args> requires (!view<C>) constexpr C to(R&& r, Args&&... args);-1- Returns: An object of type C constructed from the elements of r in the following manner:
(1.1) — If convertible_to<range_reference_t<R>, range_value_t<C>> is true:
(1.1.1) — If constructible_from<C, R, Args...> is true:
C(std::forward<R>(r), std::forward<Args>(args)...)(1.1.2) — Otherwise, if constructible_from<C, const from_range_t&, R, Args...> is true:
C(from_range, std::forward<R>(r), std::forward<Args>(args)...)- […]
[ 2023-02-02; Reflector poll ]
Set priority to 4 after reflector poll. Several votes for "Tentatively Ready", but also two objections, preferring NAD. The proposed change would appear to bless unconventional uses of from_range, and we don't want to support or encourage that. The current wording is simpler, and works for the intended cases.
In bullet (1.1.2), ranges::to checks whether the container type C models constructible_from<from_range_t, ...> and constructs it via C(from_range, ...).
Since from_range is a constexpr variable here, it would be more accurate to constrain C to be constructible from a const lvalue tag rather than an rvalue tag.
History | |||
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Date | User | Action | Args |
2023-02-02 15:14:57 | admin | set | messages: + msg13254 |
2023-01-06 14:50:57 | admin | set | messages: + msg13177 |
2023-01-06 00:00:00 | admin | create |