Workarounds for this problem are worse than the problem itself. The library could return a pair with the vector and `std::unique_ptr<std::pmr::memory_resource>` which the caller must manage. Or the library could change its function signatures to accept a {ref_memory_resource}``*`` provided by the caller, where the library also makes public the desired memory resources (`my_resource` above).

Boost.JSON solves this problem by introducing a new smart pointer called <<ref_storage_ptr>> which builds upon {cpp}17's memory allocation interfaces, accomplishing the goals above. As a result, libraries which use this type compose more easily and enjoy faster compilation, as member functions for containers which use the type can be defined out-of-line.