pfr_non_boost VS pfr

Here it's possible to serialize/deserialize this structure in a generic way without having to annotate it - currently it's a bit complicated to implement so libraries help doing it (e.g.https://github.com/apolukhin/pfr_non_boost) but in 23 the missing language feature that makes the code trivial to write without any library should be there.

This single feature opens a world of new possiblities. For example, it makes implementing "getting the number of fields" trivial. Furthrmore, and much more importantly, it enables turning a struct into a tuple. Currently, this can only be done by enumerating cases (therefore it's not fully generic), as with Boost PFR. By the way, PFR greatly simplifies our codebases, especially for parts with serialization and/or reflection.

The code is relatively short and can be groked with a few coffees: https://github.com/boostorg/pfr/tree/develop/include/boost/pfr ; if you're using C++17 it uses a binary search (https://github.com/boostorg/pfr/blob/develop/include/boost/pfr/detail/fields_count.hpp) to count the number of fields in a struct, by starting by the observation that a likely majorant on the number of fields in a struct is sizeof(the struct) * CHAR_BIT, assuming not too many [[no_unique_address]] tomfooleries. Then once this count is known it's possible to simply map them as a tuple through sheer brute force and destructuring: https://github.com/boostorg/pfr/blob/develop/include/boost/pfr/detail/core17_generated.hpp

I wonder if the c++ approach of boost.pfr would be portable to rust ? It allows reflection on aggregates without needing to annotate anything: https://github.com/boostorg/pfr

It is an 'interesting' meta-programming problem though (wasted many weeks on it myself, fixed a small gcc bug - a 'uniform init' edge case and filed an issue with magic_get Reflecting array members of aggregate structs).