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0 pointsSuperV12341mo ago0 comments

It is kind of weird at first but the reason is that `std::vector` requires heap allocation and transient allocations are not allowed in `constexpr` contexts. The purpose of `std::define_static_array` is to promote the storage of the vector to static storage to eliminate the transient allocation issue, and so that the `template for` can work properly with it.

See wg21.link/P3491

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mort961mo ago· 2 in thread

Is there a reason why `std::meta::enumerators_of`, a reflection feature that's surely almost exclusively going to be used in constexpr contexts, returns a value which doesn't work in constexpr contexts?

SuperV1234OP1mo ago

It works generally, but not with expansion statements. See section 3.2 here: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p13...

It seems that this is being worked on, and eventually the `define_static_array` won't be needed anymore

mort961mo ago

Just another example where C++ language features are incompatible with each other, to be fixed "in a later version" which may or may not happen. There are so many of those in C++. I desperately wish they'd just do it properly initially.

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