It sounds like you're trying to link with your resulting object file with gcc instead of g++:
Note that programs using C++ object files must always be linked with g++, in order to supply the appropriate C++ libraries. Attempting to link a C++ object file with the C compiler gcc will cause "undefined reference" errors for C++ standard library functions:
$ g++ -Wall -c hello.cc
$ gcc hello.o (should use g++)
hello.o: In function `main':
hello.o(.text+0x1b): undefined reference to `std::cout'
.....
hello.o(.eh_frame+0x11):
undefined reference to `__gxx_personality_v0'
Source: An Introduction to GCC - for the GNU compilers gcc and g++