为什么 std::invoke 不是 constexpr？
Why is `std::invoke` not constexpr?
不应该std::invoke be constexpr especially after constexpr lambdas in C++17吗？
是否有任何障碍可以阻止这种情况发生？
更新： P1065 将会 constexpr.
由于历史原因，保持原来的post：
来自the proposal：
Although there is possibility to implement standard conforming invoke function template as a constexpr function, the proposed wording does not require such implementation. The main reason is to left it consistent with existing standard function objects, that could have such definition, like std::mem_fn, std::reference_wrapper and operator wrappers. Furthermore imposing such requirement will block the implementation of invoke that refers to std::mem_fn.
This proposal assumes that constexpr addition to the header would be applied consistently by a separate proposal.
Both constexpr and standard library based implementation are presented in Implementability section of the proposal.
相关 CWG 问题 #1581：When are constexpr member functions defined?。
不应该std::invoke be constexpr especially after constexpr lambdas in C++17吗？
是否有任何障碍可以阻止这种情况发生？
更新： P1065 将会 constexpr.
由于历史原因，保持原来的post：
来自the proposal：
Although there is possibility to implement standard conforming invoke function template as a constexpr function, the proposed wording does not require such implementation. The main reason is to left it consistent with existing standard function objects, that could have such definition, like std::mem_fn, std::reference_wrapper and operator wrappers. Furthermore imposing such requirement will block the implementation of invoke that refers to std::mem_fn.
This proposal assumes that constexpr addition to the header would be applied consistently by a separate proposal.
Both constexpr and standard library based implementation are presented in Implementability section of the proposal.
相关 CWG 问题 #1581：When are constexpr member functions defined?。