In an effort to test out google's protobuf, I starting by creating a project from their c++ tutorial. This worked, when compiled with clang++, but not with g++. I created an autotools configuration so that this could be compiled easily and the compiler could be changed easily for testing.
autoreconf -vfi && ./configure && make
Inside of configure.ac there are lines
AC_PROG_CXX
#AC_PROG_CXX([g++-5])
#AC_PROG_CXX([clang++])
The first one takes the default for the machine. The other two specify specific compilers. Leave only one uncommented to change compilers.
Brew provides protobuf precompiled with clang++. Since the ABI for clang++ compiled libraries is not compatible with that of g++, protobuf must be downloaded and recompiled. For me, running the following commands used g++-5 without having to change anything else. If this is not the case open up configure.ac and change AC_PROG_CXX to AC_PROG_CXX([g++-5]) and run autoreconf -vfi.
cd protobuf-2.6.1
./configure --prefix=/build/protobuf/2.6.1
make -j16
sudo make install
cd protobuf_addressbook
# Make change to use g++-5 if necessary
autoreconf -vfi && ./configure && make clean && make
DYLD_LIBRARY_PATH=.:./lib ./main addressbook.dat