synchronized_pool_resource();

explicit synchronized_pool_resource( std::pmr::memory_resource* upstream );

explicit synchronized_pool_resource( const std::pmr::pool_options& opts );

synchronized_pool_resource( const std::pmr::pool_options& opts,
                            std::pmr::memory_resource* upstream );

synchronized_pool_resource( const synchronized_pool_resource& ) = delete;

1-4) Constructs a synchronized_pool_resource using the specified upstream memory resource and tuned according to the specified options. The resulting object holds a copy of upstream but does not own the resource to which upstream points.
The overloads not taking opts as a parameter uses a default constructed instance of pool_options as the options. The overloads not taking upstream as a parameter uses the return value of std::pmr::get_default_resource as the upstream memory resource.

5) Copy constructor is deleted.

1-4) Throws only if a call to the allocate() function of the upstream resource throws. It is unspecified if or under what conditions such a call takes place.