shared_ptr causes an infinite recursion when used in the redefinition of global operators new/delete. This is caused by sp_counted_base_impl being allocated on the heap via global operators new/delete. There currently are alternative allocation schemes which clients can select via macros but all current schemes (eventually) explicitly invoke global operators new/delete to de/allocate memory. The proposed patch I’ve included just adds another choice of allocation scheme to sp_counted_base_impl with the existing ones by doing exactly the same method. It forwards de/allocation requests to C memory functions std::malloc and std::free. Clients of shared_ptr may select the alternative allocation scheme by defining the macro BOOST_SP_USE_MALLOC_ALLOCATOR before inclusion of shared_ptr/smart_ptr.hpp.

From Korcan Hussein.