λ cat test.ss
(import (chicken platform))

(cond-expand
 (debug (display "DEBUG"))
 (else  (display "NOT DEBUG")))

(newline)
(newline)

(display (features))


λ csc -Ddebug test.ss -o test; ./test
DEBUG

(srfi-28: srfi-31: srfi-26: srfi-16: srfi-15: srfi-11: srfi-0: srfi-2: srfi-6: srfi-9: srfi-46: srfi-55: srfi-61: chicken-5: chicken-5.3: 64bit: ptables: dload: little-endian: x86-64: gnu: linux: unix: chicken: srfi-6: srfi-8: srfi-12: srfi-17: srfi-23: srfi-30: srfi-39: srfi-62: srfi-87: srfi-88: full-numeric-tower:) <- no `debug` flag