Definition of _gfortran_os_error?

[Alberto Luaces]

Hello,

I'm writing a mixed C++/Fortran program and recently I came into a linker 
error about _gfortran_os_error, when linking with g++ and -lgfortran:

$ g++ cbfg.o cbf.o -o cbf4 -lgfortran
cbf.o: In function `rellenar_array':
/home/alberto/testsFortran/c_binding3.f90:20: undefined reference to 
`_gfortran_os_error'

 On the other hand, if I link with gfortran and -lstdc++, it works although 
objdump says that symbol is undefined:

$ gfortran cbfg.o cbf.o -o cbf4 -lstdc++

$ objdump -tT ./cbf4 | grep os_error
0000000000000000       F *UND*  000000000000002c              
_gfortran_os_error@@GFORTRAN_1.0
0000000000000000      DF *UND*  000000000000002c  GFORTRAN_1.0 
_gfortran_os_error

I really wanted to link with g++ instead of gfortran, does anyone know which 
special flag is using gfortran at linking time in order to bypass that error?

My specs:

gcc version 4.2.4 (Debian 4.2.4-1)
gcc version 4.3.1 20080523 (prerelease) (Debian 4.3.0-5)

Thank you,

Alberto