Safe. Indeed it is not built using b2, moreover this file is removed from future versions, I guess 1.60 will free of this file.

But let Robert Ramey reassure it

From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Fairlie
Sent: Tuesday, October 06, 2015 11:07 AM
To: Boost-users@lists.boost.org
Subject: [Boost-users] serialization code compilation problem - shared_ptr_helper.cpp in Boost 1.59

I tried building the serialization library only using the standard b2 approach and looking at the output. It looks like shared_ptr_helper.cpp isn’t included in the build (at least for serialization). So I just left it out of my own build and my code compiled and linked OK, and my serialization seems to be working.

Does this approach sound safe or am I overlooking something?