Error during project build "alt_main"

/cygdrive/c/altera/91/nios2eds/components/altera_hal/HAL/src/alt_main.c:165: undefined reference to `main'

collect2: ld returned 1 exit status

When i change the source code from *.c to *.C, i am seeing this error during compilation.

Something extra setting needed in order to support C++?