karlsson@karlsson-laptop:~/poly$ make
gcc -g -pedantic -std=c99 -Wall -Werror -c -o poly.o poly.c
poly.c:14: error: conflicting types for poly_t
poly.h:4: error: previous declaration of poly_t was here
poly.c:25: error: conflicting types for new_poly_from_string
poly.h:6: error: previous declaration of new_poly_from_string was here
poly.c:47: error: conflicting types for free_poly
poly.h:7: error: previous declaration of free_poly was here
poly.c:51: error: conflicting types for poly_to_string
poly.h:9: error: previous declaration of poly_to_string was here
poly.c:56: error: conflicting types for add
poly.h:11: error: previous declaration of add was here
poly.c:61: error: conflicting types for mul
poly.h:12: error: previous declaration of mul was here
poly.c:65: error: conflicting types for print_poly
poly.h:14: error: previous declaration of print_poly was here
cc1: warnings being treated as errors
poly.c:70: warning: return type of main is not int
make: *** [poly.o] Error 1
karlsson@karlsson-laptop:~/poly$