Identical to, or derived from true_type if the allocators of parameterized ALLOCATOR_TYPE should be swapped when containers using that ALLOCATOR_TYPE are swapped; otherwise identical to or derived from false_type. This type is ALLOCATOR_TYPE::propagate_on_container_swap if such a type is defined, and false_type otherwise.
Declared in <bslma_allocatortraits.h>
typedef BloombergLP::bslma::AllocatorTraits_PropOnSwap<ALLOCATOR_TYPE>::type propagate_on_container_swap;