Fedora package adds the make_cflags_work.patch that adds this line to Chicken's default.make:

C_COMPILER_OPTIONS += $(CFLAGS)

CFLAGS contains -Wall that causes gcc to complain about undefined variables that Chicken generates, eg.

$ cat > hello.scm
(display "Hello, World!\n")
$ csc hello.scm
hello.c: In function ‘f_13’:
hello.c:50:8: warning: unused variable ‘t4’ [-Wunused-variable]
 C_word t4;
        ^
hello.c: In function ‘C_toplevel’:
hello.c:71:8: warning: unused variable ‘t3’ [-Wunused-variable]
 C_word t3;
        ^
hello.c: In function ‘f_11’:
hello.c:97:8: warning: unused variable ‘t3’ [-Wunused-variable]
 C_word t3;
        ^
hello.c: In function ‘f_15’:
hello.c:110:9: warning: unused variable ‘a’ [-Wunused-variable]
 C_word *a;
         ^
hello.c:108:8: warning: unused variable ‘tmp’ [-Wunused-variable]
 C_word tmp;
        ^
hello.c: In function ‘f_18’:
hello.c:118:9: warning: unused variable ‘a’ [-Wunused-variable]
 C_word *a;
         ^
hello.c:116:8: warning: unused variable ‘tmp’ [-Wunused-variable]
 C_word tmp;
        ^
hello.c: In function ‘f_9’:
hello.c:126:8: warning: unused variable ‘t3’ [-Wunused-variable]
 C_word t3;
        ^
hello.c: At top level:
hello.c:20:15: warning: ‘C_possibly_force_alignment’ defined but not used [-Wunused-variable]
 static double C_possibly_force_alignment;
               ^
hello.c:21:21: warning: ‘li0’ defined but not used [-Wunused-variable]
 static C_char C_TLS li0[] C_aligned={C_lihdr(0,0,10),40,116,111,112,108,101,118,101,108,41,0,0,0,0,0,0};
                     ^