With a little bit of cleverness, we can add best::span to the fwd.h header.
The primary obstacle was that it has a best::option<size_t> template parameter, which is not defined until way later. However, by making that size_t dependent on the first template parameter, we eliminate this problem by forcing two-phase lookup.
With a little bit of cleverness, we can add
best::spanto thefwd.hheader.The primary obstacle was that it has a
best::option<size_t>template parameter, which is not defined until way later. However, by making thatsize_tdependent on the first template parameter, we eliminate this problem by forcing two-phase lookup.