What does brew's "dependency gcc was built with a different C++ standard" mean?

I installed boost with c++11 support using brew and I got the warning message boost dependency gcc was built with a different C++ standard library (libstdc++ from clang). This may cause problems at runtime.. What does this mean?

$ brew install boost --c++11 --with-mpi --without-single --with-python
==> Using Homebrew-provided fortran compiler.
This may be changed by setting the FC environment variable.
==> Downloading http://ift.tt/1IdG6ug
==> Downloading from http://ift.tt/1OqzVlB
######################################################################## 100.0%
==> ./bootstrap.sh --prefix=/usr/local/Cellar/boost/1.58.0 --libdir=/usr/local/Cellar/boost/1.58.0/lib --without-icu --without-
==> ./b2 --prefix=/usr/local/Cellar/boost/1.58.0 --libdir=/usr/local/Cellar/boost/1.58.0/lib -d2 -j4 --layout=tagged --user-con
Warning: boost dependency gcc was built with a different C++ standard
library (libstdc++ from clang). This may cause problems at runtime.
🍺  /usr/local/Cellar/boost/1.58.0: 10668 files, 316M, built in 20.6 minute