Dne 27.12.2011 14:57, Michal Hocko napsal(a):

Anyway, I am wondering why unused-but-set-variable is disabled while
unused-variable is enabled.

unused-but-set-variable was disabled, because it was a new warning in
gcc 4.6 and produced too much noise relatively to its severity. A make
W=1 build of x86_64_defconfig gives:
$ grep -c 'Wunused-but-set-variable' log
77
$ grep -c 'Wunused-variable' log
0

More exotic configuration will probably result in a couple of unused
variable warnings, but that IMO no reason to disable them globally.

Shouldn't we just disable it as well rather
than workaround this in the code? The warning is just pure noise in this
case.

If it's noise in a particular case, there is always the option to add

CFLAGS_memcontrol.o := $(call cc-disable-warning, unused-variable)

to the respective Makefile.

Michal