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Section: 20.5.1 [tuple.general] Status: C++17 Submitter: Vincent Reverdy Opened: 2016-09-10 Last modified: 2017-07-30
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Currently std::ignore is not specified constexpr according to the C++ draft N4606 in the paragraph 20.5.1 [tuple.general]. It prevents some use in constexpr context: for example declaring a constexpr variable equals to the result of a function to which std::ignore has been passed as a parameter:
constexpr int i = f(std::ignore); // Won't compile
If there is no fundamental reason preventing std::ignore to be constexpr, then we propose to declare it as constexpr instead of as const.
[Issues processing Telecon 2016-10-7]
P0; set to Tentatively Ready
This wording is relative to N4606.
Modify 20.5.1 [tuple.general] as indicated:
// 18.104.22.168, tuple creation functions: