Both -Wunused-parameter and -Wshadow were added to gcc long ago. In
particular gcc-4.6.3, which ships with Ubuntu-12.04, supports them. It
should thus be safe to enable both warnings unconditionally.
CFLAGS += -Werror-implicit-function-declaration
CFLAGS += -Wmissing-format-attribute
CFLAGS += -Wunused-macros
+CFLAGS += -Wunused-parameter
CFLAGS += -Wbad-function-cast
+CFLAGS += -Wshadow
Makefile.deps: $(wildcard *.c *.h)
gcc -MM -MG *.c > $@