Just looked at what unkle clang says in the [build 215.2](https://travis-ci.org/SOCI/soci/jobs/5345895):
```
/home/travis/build/SOCI/soci/src/core/session.cpp:46:27: warning: field 'pool_'
  will be initialized after field 'backEnd_' [-Wreorder]
  isFromPool_(false), pool_(NULL), backEnd_(NULL)
                               ^
```