Should flat_multiset be done in the same file, or should we granularize this into <__flat_set/flat_set.h> and <__flat_set/flat_multiset.h> before taking the next step? I tentatively think "two files," but only because that would make it easier to ensure things like "the identifier flat_set doesn't accidentally appear anywhere in flat_multiset.h nor vice versa." We don't expect any future standard header ever to include either of the granular headers alone.
If we introduce __flat_set/, should sorted_unique.h and sorted_equivalent.h move into that directory? I tentatively think "yes," but I wouldn't like to bet on these types' never being reused by another STL facility. Compare __utility/in_place.h (used only in <any>, <expected>, <optional>, <ranges>, <variant>) but __variant/monostate.h (used only in <variant>).
After this:
flat_multisetbe done in the same file, or should we granularize this into<__flat_set/flat_set.h>and<__flat_set/flat_multiset.h>before taking the next step? I tentatively think "two files," but only because that would make it easier to ensure things like "the identifierflat_setdoesn't accidentally appear anywhere inflat_multiset.hnor vice versa." We don't expect any future standard header ever to include either of the granular headers alone.__flat_set/, shouldsorted_unique.handsorted_equivalent.hmove into that directory? I tentatively think "yes," but I wouldn't like to bet on these types' never being reused by another STL facility. Compare__utility/in_place.h(used only in<any>,<expected>,<optional>,<ranges>,<variant>) but__variant/monostate.h(used only in<variant>).